ALBERT

Beschreibung: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 176〈/p〉 〈p〉Author(s): Hoheok Kim, Tatsuki Yamamoto, Yushi Sato, Junya Inoue〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigate the viability of establishing low-cost surrogate structure-property (S–P) linkages by introducing a Bayesian model selection method to extend the Materials Knowledge Systems (MKS) homogenization framework, which employs the n-point spatial correlation function, principal component analysis, and regression techniques. In particular, we place emphasis not only on choosing the important structural features but also on interpreting their implications for the property under consideration. First, the yield strengths of synthetic microstructures with various morphological characteristics are estimated by physics-based crystal plasticity simulation. Then, the dimension-reduced microstructural features are revealed by a combination of 2-point spatial correlations and principal component analysis. The Bayesian model selection method is further applied to establish a microstructure-to-yield-strength surrogate model. Finally, the model is validated with an independent dataset and its constituent features are interpreted with a morphology reconstruction based on a Monte Carlo algorithm. The method is found to be capable of interpreting the key microstructural features as well as modeling the mechanical response of a dual-phase metallic composite in consideration of the diverse microstructural factors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304367-fx1.jpg" width="274" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 176〈/p〉 〈p〉Author(s): Denise C. Ford, David Hicks, Corey Oses, Cormac Toher, Stefano Curtarolo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metallic glasses are excellent candidates for biomedical implant applications due to their inherent strength and corrosion resistance. However, use of metallic glasses in structural applications is limited because bulk dimensions are challenging to achieve. Glass-forming ability (GFA) varies strongly with alloy composition and becomes more difficult to predict as the number of chemical species in a system increases. Here, we present a theoretical model — implemented in the AFLOW framework — for predicting GFA based on the competition between crystalline phases. The model is applied to biologically relevant binary and ternary systems. Elastic properties of Ca- and Mg-based systems are estimated for use in biodegradable orthopedic support applications. Alloys based on Ag〈sub〉0.33〈/sub〉Mg〈sub〉0.67〈/sub〉, Cu〈sub〉0.5〈/sub〉Mg〈sub〉0.5〈/sub〉, Cu〈sub〉0.37〈/sub〉Mg〈sub〉0.63〈/sub〉, and Cu〈sub〉0.25〈/sub〉Mg〈sub〉0.5〈/sub〉Zn〈sub〉0.25〈/sub〉, and in the Ag-Ca-Mg and Ag-Mg-Zn systems, are recommended for further study.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304380-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 218〈/p〉 〈p〉Author(s): Yuwei Liu, Biao Kuang, Benjamin B. Rothrauff, Rocky S. Tuan, Hang Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mesenchymal stem cells (MSCs) embedded in their secreted extracellular matrix (mECM) constitute an exogenous scaffold-free construct capable of generating different types of tissues. Whether MSC-mECM constructs can recapitulate endochondral ossification (ECO), a developmental process during 〈em〉in vivo〈/em〉 skeletogenesis, remains unknown. In this study, MSC-mECM constructs are shown to result in robust bone formation both 〈em〉in vitro〈/em〉 and 〈em〉in vivo〈/em〉 through the process of endochondral ossification when sequentially exposed to chondrogenic and osteogenic cues. Of interest, a novel trypsin pre-treatment was introduced to change cell morphology, which allowed MSC-mECM constructs to undergo the N-cadherin-mediated developmental condensation process and subsequent chondrogenesis. Furthermore, bone formation by MSC-mECM constructs were significantly enhanced by the ECO protocol, as compared to conventional 〈em〉in vitro〈/em〉 culture in osteogenic medium alone. This was designed to promote direct bone formation as seen in intramembranous ossification (IMO). The developmentally informed method reported in this study represents a robust and efficacious approach for stem-cell based bone generation, which is superior to the conventional osteogenic induction procedure.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 217〈/p〉 〈p〉Author(s): Jun Yang, Shaodong Zhai, Huan Qin, He Yan, Da Xing, Xianglong Hu〈/p〉

Beschreibung: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 176〈/p〉 〈p〉Author(s): Manuel J. Pfeifenberger, Vladica Nikolić, Stanislav Žák, Anton Hohenwarter, Reinhard Pippan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The brittleness of tungsten at room temperature represents a severe challenge particularly for structural applications. Tungsten composites, consisting of foils or wires, overcome this low ductility by utilizing the remarkable mechanical properties of ultrafine grained tungsten materials. A comprehensive understanding of the fracture behaviour of these ultrafine grained tungsten materials is therefore essential for a further development of high performance structural composites. However, the dimensions of specimens used for classical fracture toughness experiments are not applicable to test all important crack growth directions in the case of thin foils and wires, especially, in the direction of the presumably lowest fracture toughness, which is along their characteristically elongated microstructure. Femtosecond laser processing allows to fabricate micro single leg bending specimens, which enable to properly evaluate the fracture toughness in this orientation. The fracture toughness value at crack initiation found for the foil is 2.4  〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mtext〉MPa〈/mtext〉〈msqrt〉〈mtext〉m〈/mtext〉〈/msqrt〉〈/math〉, whereas for the wire a value of 5.3  〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mtext〉MPa〈/mtext〉〈msqrt〉〈mtext〉m〈/mtext〉〈/msqrt〉〈/math〉 was determined. In both cases the results are significantly below the values reported for other orientations. This strongly anisotropic fracture behaviour is responsible for the reduced brittle to ductile transition temperature and the delamination induced toughening for crack orientations perpendicular to the elongated ultrafine grained structure. The distinct difference of the fracture toughness at crack initiation and the R-curve between wire and foil specimens could be primarily explained by the morphologies of the fracture surfaces, exhibiting significantly different roughnesses of the evolving crack paths.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304252-fx1.jpg" width="497" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 176〈/p〉 〈p〉Author(s): Peter Müllner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent reports on highly mobile type II twin boundaries challenge the established understanding of deformation twinning and motivate this study. We consider the motion of twin boundaries through the nucleation and growth of disconnection loops and develop a mechanism-based model for twin boundary motion in the framework of isotropic linear elasticity. While such mechanisms are well established for type I and compound twins, we demonstrate based on the elastic properties of crystals that type II twin boundaries propagate in a similar way. Nucleation of a type I twinning disconnection loop occurs in a discrete manner. In contrast, nucleation of a type II twinning disconnection loop occurs gradually with increasing Burgers vector. The gradual nucleation of a type II disconnection loop accounts for the higher mobility of type II twin boundaries compared with type I twin boundaries. We consider the homogeneous nucleation of a disconnection loop, which is adequate for twinning in shape memory alloys with a low-symmetry crystal lattice. For the magnetic shape memory alloy Ni–Mn-Ga, the model predicts twinning stresses of 0.33 MPa for type II twinning and 4.7 MPa for type I twinning. Over a wide temperature range, the twinning stress depends on temperature only through the temperature dependence of the elastic constants, in agreement with experimental results.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304343-fx1.jpg" width="374" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Cuncai Fan, Qiang Li, Jie Ding, Yanxiang Liang, Zhongxia Shang, Jin Li, Ruizhe Su, Jaehun Cho, Di Chen, Yongqiang Wang, Jian Wang, Haiyan Wang, Xinghang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉There are increasing studies that show nanotwinned (NT) metals have enhanced radiation tolerance. However, the mechanical deformability of irradiated nanotwinned metals is a largely under explored subject. Here we investigate the mechanical properties of He ion irradiated nanotwinned Cu with preexisting nanovoids. In comparison with coarse-grained Cu, nanovoid nanotwinned (NV-NT) Cu exhibits prominently improved radiation tolerance. Furthermore, 〈em〉in situ〈/em〉 micropillar compression tests show that the irradiated NV-NT Cu has an ultrahigh yield strength of ∼ 1.6 GPa with significant plasticity. Post radiation analyses show that twin boundaries are decorated with He bubbles and thick stacking faults. These stacking fault modified twin boundaries introduce significant strengthening in NT Cu. This study provides further insight into the design of high-strength, advanced radiation tolerant nanostructured materials for nuclear reactor applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304331-fx1.jpg" width="307" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 176〈/p〉 〈p〉Author(s): Y. Kobayashi, J. Takahashi, K. Kawakami〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of a pre-deformation with a true strain of 0.5 on the precipitation behavior during isothermal aging at 580 °C in ferritic steel containing 0.03C-0.1Ti-0.20Mn–3Al (mass %) was investigated. Atom probe tomography (APT) analysis revealed that titanium carbide (TiC) precipitates much earlier and more finely in pre-deformed steel than in steel without a pre-deformation. It was found that the precipitation sites of TiC are not only located on the dislocations but are also distributed homogeneously in a matrix in pre-deformed steel. In steel without a pre-deformation, coarse cementite first precipitates during the early stage of aging, and the cementite then dissolves owing to the subsequent precipitation of TiC. Meanwhile, in pre-deformed steel, cementite has difficulty precipitating, and carbon atoms are considered to segregate to high-density dislocations during the early stage of aging prior to the precipitation of TiC. A kinetic model that explains the difference between the precipitation behaviors of steel with and without a pre-deformation is proposed. Moreover, the difference observed between TiC particle strengthening in steel with and without a pre-deformation is discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930429X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 217〈/p〉 〈p〉Author(s): Xiao-Juan Wang, Gao-Feng Shu, Xiao-Ling Xu, Chen-Han Peng, Chen-Ying Lu, Xing-Yao Cheng, Xiang-Chao Luo, Jie Li, Jing Qi, Xu-Qi Kang, Fei-Yang Jin, Min-Jiang Chen, Xiao-Ying Ying, Jian You, Yong-Zhong Du, Jian-Song Ji〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spinal cord injury (SCI) leads to immediate disruption of neuronal membranes and loss of neurons, followed by extensive secondary injury process. Treatment of SCI still remains a tremendous challenge clinically. Minocycline could target comprehensive secondary injury via anti-inflammatory, anti-oxidant and anti-apoptotic mechanisms. Polyethylene glycol (PEG), a known sealing agent, is able to seal the damaged cell membranes and reduce calcium influx, thereby exerting neuroprotective capacity. Here, an E-selectin-targeting sialic acid - polyethylene glycol – poly (lactic-co-glycolic acid) (SAPP) copolymer was designed for delivering hydrophobic minocycline to achieve combinational therapy of SCI. The obtained SAPP copolymer could self-assemble into micelles with critical micelle concentration being of 13.40 μg/mL, and effectively encapsulate hydrophobic minocycline. The prepared drug-loaded micelles (SAPPM) displayed sustained drug release over 72 h, which could stop microglia activation and exhibited excellent neuroprotective capacity 〈em〉in vitro〈/em〉. The SAPP micelles were efficiently accumulated in the lesion site of SCI rats via the specific binding between sialic acid and E-selectin. Due to the targeting distribution and combinational effect between PEG and minocycline, SAPPM could obviously reduce the area of lesion cavity, and realize more survival of axons and myelin sheaths from the injury, thus distinctly improving hindlimb functional recovery of SCI rats and conferring superior therapeutic effect in coparison with other groups. Our work presented an effective and safe strategy for SCI targeting therapy. Besides, neuroprotective capacity of PEG deserves further investigation on other central nervous system diseases.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219304259-fx1.jpg" width="312" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 217〈/p〉 〈p〉Author(s): Dandan Zhang, Liewei Wen, Ru Huang, Huanhuan Wang, Xianglong Hu, Da Xing〈/p〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 218〈/p〉 〈p〉Author(s): Shao-Kai Sun, Jian-Cheng Wu, Haoyu Wang, Li Zhou, Cai Zhang, Ran Cheng, Di Kan, Xuejun Zhang, Chunshui Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bioavailable persistent luminescence material is an ideal internal light source for long-term photodynamic therapy, but inevitably suffers from low utilization efficiency and weak persistent luminescence due to corrosion and screening processes. Herein, we show a facile and smart “turning solid into gel” strategy to fabricate persistent luminescence hydrogel for high-efficient persistent luminescence-sensitized photodynamic therapy. The homogeneous persistent luminescence hydrogel was synthesized via dispersing high-temperature calcined persistent luminescence material without corrosion and screening into a biocompatible alginate-Ca〈sup〉2+〈/sup〉 hydrogel. The simple synthesis strategy allows 100% of utilization efficiency and intact persistent luminescence of persistent luminescence material. The persistent luminescence hydrogel possesses favorable biocompatibility, bright persistent luminescence, red light renewability, good syringeability, and strong fixing ability in tumors. The persistent luminescence hydrogel can be easily injected in vivo as a powerful localized light source for superior persistent luminescence-sensitized photodynamic therapy of tumors. The “turning solid into gel” strategy enables taking full advantages of persistent luminescence for biological applications, and shows great potential in utilizing diverse theranostic agents regardless of hydrophilicity and hydrophobicity.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 218〈/p〉 〈p〉Author(s): Shijie Zhen, Xiaoqing Yi, Zujin Zhao, Xiaoding Lou, Fan Xia, Ben Zhong Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The combination of photodynamic therapy (PDT) and chemotherapy (CT) offers a promising approach for the tumor eradication for overcoming multidrug resistance (MDR), which is a major obstacle to effective cancer treatment. However, for PDT, simultaneously achieving near-infrared (NIR) emission and efficient reactive oxygen species (ROS) generation with low dark toxicity is urgently needed but remains challenging. Herein, a series of novel fluorophores with strong NIR emission, hybridized local and charge transfer characteristics, good two-photon absorption, high photostability, low dark cytotoxicity and excellent ROS generation ability are developed. By encapsulating the NIR fluorophore (DEB-BDTO) as a photosensitizer along with a drug resistance inhibitor tariquidar (TQR) within a polymeric prodrug (PMP), a reduction-sensitive drug co-delivery system (DEB/TQR@PMP micelles) is constructed. The DEB/TQR@PMP micelles exhibit a prominent synergistic lethal effect of PDT and CT on SKOV-3 cells and SKOV-3/MDR cells, and can apparently enhance the inhibition of tumor growth compared with sole PDT or CT in the tumor-bearing mouse model. Both in vitro and in vivo experiments prove that the new NIR fluorophores are excellent photosensitizers and can furnish an efficient combination therapy of image-guided PDT and CT within drug delivery micelles, which is particularly useful for eradicating multidrug resistance cancer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219304296-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 217〈/p〉 〈p〉Author(s): Yanlin Feng, Yan Cheng, Yun Chang, Hui Jian, Runxiao Zheng, Xiaqing Wu, Keqiang Xu, Li Wang, Xiaomin Ma, Xi Li, Haiyuan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photochemotherapy is currently an effective anticancer therapy. Recently, it has been reported that cancer cells pretreated with epidermal growth factor receptor (EGFR) inhibitor erlotinib (Erl) can significantly synergize its apoptosis against the DNA damaging agent doxorubicin (Dox). As a result, we designed two gold nanocages (Au NCs) microcontainers covered with different smart polymer shell-PAA (pH responsive) and 〈em〉p〈/em〉 (NIPAM-co-AM) (temperature responsive) containing Erl and Dox respectively. The acidic tumor microenvironment and NIR light irradiation can selectively activate the release of Erl and Dox. Time staggered release of Erl and Dox and photothermal therapy enhance the apoptotic signaling pathways, resulting in improved tumor cell killing in both MCF-7 (low EGFR expression) and A431 (very high EGFR expression) tumor cells, but more efficient in the latter. The photochemotherapy strategy controls the order and duration of drug exposure precisely in spatial and temporal, and significantly improves the therapeutic efficacy against high EGFR expressed tumors.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 217〈/p〉 〈p〉Author(s): Alexander J. Engler, Micha Sam B. Raredon, Andrew V. Le, Yifan Yuan, Yan A. Oczkowicz, Ellen L. Kan, Pavlina Baevova, Laura E. Niklason〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microvascular leak is a phenomenon witnessed in multiple disease states. In organ engineering, regaining a functional barrier is the most crucial step towards creating an implantable organ. All previous methods of measuring microvascular permeability were either invasive, lengthy, introduced exogenous macromolecules, or relied on extrapolations from cultured cells. We present here a system that enables real-time measurement of microvascular permeability in intact rat lungs. Our unique system design allows direct, non-invasive measurement of average alveolar and capillary pressures, tracks flow paths within the organ, and enables calculation of lumped internal resistances including microvascular barrier. We first describe the physiology of native and decellularized lungs and the inherent properties of the extracellular matrix as functions of perfusion rate. We next track changing internal resistances and flows in injured native rat lungs, resolving the onset of microvascular leak, quantifying changing vascular resistances, and identifying distinct phases of organ failure. Finally, we measure changes in permeability within engineered lungs seeded with microvascular endothelial cells, quantifying cellular effects on internal vascular and barrier resistances over time. This system marks considerable progress in bioreactor design for intact organs and may be used to monitor and garner physiological insights into native, decellularized, and engineered tissues.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Yan Zhang, Lu Zhang, Zhenzhen Wang, Faming Wang, Lihua Kang, Fangfang Cao, Kai Dong, Jinsong Ren, Xiaogang Qu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Covalent organic frameworks (COFs) and their derivatives represent an emerging class of crystalline porous materials with broad potential applications. However, the biomedical applications of them were limited by the large size, low dispersivity, poor bioavailability within cells and metabolic problems. Herein, renal-clearable ultrasmall COF nanodots have been synthesized and utilized as efficient cancer therapy agents. A simple liquid exfoliation strategy was used to prepare COF nanodots. After polyethylene glycol (PEG) conjugation, the PEG coated COF nanodots (COF nanodots-PEG) showed improved physiological stability and biocompatibility. In addition, the well isolated porphyrin molecules endowed COF nanodots-PEG good light-triggered reactive oxygen species production ability, which showed excellent photodynamic therapy efficiency with good tumor accumulation ability. In particular, due to the ultrasmall size, COF nanodots-PEG could be cleared from the body through the renal filtration with no appreciable in vivo toxicity. Our study highlights the potential of COFs-based nanoparticles for biomedical applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Eun Young Jeon, Jungho Lee, Bum Ju Kim, Kye Il Joo, Ki Hean Kim, Geunbae Lim, Hyung Joon Cha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Significant tissue damage, scarring, and an intense inflammatory response remain the greatest concerns for conventional wound closure options, including sutures and staples. In particular, wound closure in internal organs poses major clinical challenges due to air/fluid leakage, local ischemia, and subsequent impairment of healing. Herein, to overcome these limitations, inspired by endoparasites that swell their proboscis to anchor to host's intestines, we developed a hydrogel-forming double-layered adhesive microneedle (MN) patch consisting of a swellable mussel adhesive protein (MAP)-based shell and a non-swellable silk fibroin (SF)-based core. By possessing tissue insertion capability (7-times greater than the force for porcine skin penetration), MAP-derived surface adhesion, and selective swelling-mediated physical entanglement, our hydrogel-forming adhesive MN patch achieved 〈em〉ex vivo〈/em〉 superior wound sealing capacity against luminal leaks (139.7 ± 14.1 mmHg), which was comparable to suture (151.0 ± 23.3 mmHg), as well as 〈em〉in vivo〈/em〉 excellent performance for wet and/or dynamic external and internal tissues. Collectively, our bioinspired adhesive MN patch can be successfully used in diverse practical applications ranging from vascular and gastrointestinal wound healing to transdermal delivery for pro-regenerative or anti-inflammatory agents to target tissues.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Chunguang Shen, Chenchong Wang, Xiaolu Wei, Yong Li, Sybrand van der Zwaag, Wei Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the development of the materials genome philosophy and data mining methodologies, machine learning (ML) has been widely applied for discovering new materials in various systems including high-end steels with improved performance. Although recently, some attempts have been made to incorporate physical features in the ML process, its effects have not been demonstrated and systematically analysed nor experimentally validated with prototype alloys. To address this issue, a physical metallurgy (PM) -guided ML model was developed, wherein intermediate parameters were generated based on original inputs and PM principles, e.g., equilibrium volume fraction (〈em〉V〈/em〉〈sub〉〈em〉f〈/em〉〈/sub〉) and driving force (〈em〉D〈/em〉〈sub〉〈em〉f〈/em〉〈/sub〉) for precipitation, and these were added to the original dataset vectors as extra dimensions to participate in and guide the ML process. As a result, the ML process becomes more robust when dealing with small datasets by improving the data quality and enriching data information. Therefore, a new material design method is proposed combining PM-guided ML regression, ML classifier and a genetic algorithm (GA). The model was successfully applied to the design of advanced ultrahigh-strength stainless steels using only a small database extracted from the literature. The proposed prototype alloy with a leaner chemistry but better mechanical properties has been produced experimentally and an excellent agreement was obtained for the predicted optimal parameter settings and the final properties. In addition, the present work also clearly demonstrated that implementation of PM parameters can improve the design accuracy and efficiency by eliminating intermediate solutions not obeying PM principles in the ML process. Furthermore, various important factors influencing the generalizability of the ML model are discussed in detail.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305452-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Hao Chen, Valery Levitas, Liming Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular dynamics (MD) simulations of the amorphous band nucleation and growth ahead of the tip of a shuffle 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msup〉〈mrow〉〈mn〉60〈/mn〉〈/mrow〉〈mrow〉〈mi〉o〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 dislocation pileup at different grain boundaries (GBs) in diamond-cubic (dc) silicon (Si) bicrystal under shear are performed. Amorphization initiates when the local resolved shear stress reaches approximately the same value required for amorphization in a perfect single crystal (8.6-9.3GPa) for the same amorphization plane. Since the local stresses at the tip of a dislocation pileup increase when the number of dislocations in the pileup is increased, the critical applied shear stress 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈mi〉p〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 for the formation of an amorphous shear band significantly decreases with the dislocation accumulation at the GBs. In particular, when the number of the dislocations in a pileup increases from 3 to 8, the critical shear stress drops from 4.7GPa to 1.6GPa for both the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉9〈/mn〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉19〈/mn〉〈/mrow〉〈/math〉 GBs and from 4.6GPa to 2.1GPa for the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉3〈/mn〉〈/mrow〉〈/math〉 GB, respectively. After the formation of steps and disordered embryos at the GBs, the atomistic mechanisms responsible for the subsequent amorphous shear band formations near different GBs are found to distinct from each other. For a high-angle GB, such as 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉3〈/mn〉〈/mrow〉〈/math〉, an amorphous band propagates through the crystalline phase along the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si6.svg"〉〈mrow〉〈mrow〉〈mo〉(〈/mo〉〈mrow〉〈mn〉112〈/mn〉〈/mrow〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 plane. For the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉9〈/mn〉〈/mrow〉〈/math〉 GB, partial dislocations forming a stacking fault precede the formation of an amorphous band along the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.svg"〉〈mrow〉〈mrow〉〈mo〉(〈/mo〉〈mrow〉〈mn〉110〈/mn〉〈/mrow〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 plane. For the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈mtext〉Σ〈/mtext〉〈mn〉19〈/mn〉〈/mrow〉〈/math〉 GB, the one-layer stacking fault along the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"〉〈mrow〉〈mrow〉〈mo〉(〈/mo〉〈mrow〉〈mn〉111〈/mn〉〈/mrow〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 plane transforms into an interesting intermediate phase: a two-layer band with the atomic bonds being aligned along the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"〉〈mrow〉〈mrow〉〈mo〉(〈/mo〉〈mrow〉〈mn〉111〈/mn〉〈/mrow〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 plane (i.e., rotated by 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si9.svg"〉〈mrow〉〈msup〉〈mrow〉〈mn〉30〈/mn〉〈/mrow〉〈mrow〉〈mi〉o〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 with respect to the atomic bonds outside the band). This intermediate phase transforms to the amorphous band along the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"〉〈mrow〉〈mrow〉〈mo〉(〈/mo〉〈mrow〉〈mn〉111〈/mn〉〈/mrow〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 plane under a further shearing. The obtained results represent an atomic-level confirmation of the effectiveness of dislocation pileup at the nucleation site for various strain-induced phase transformations (PTs), and exhibit some limitations.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930535X-fx1.jpg" width="218" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): K. Sofinowski, M. Šmíd, I. Kuběna, S. Vivès, N. Casati, S. Godet, H. Van Swygenhoven〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A multi-phase Ti–6Al–4V prepared by electron beam melting and thermal post treatments has been shown to exhibit increased strength and ductility over standard wrought or hot isostatic pressed Ti–6Al–4V. The mechanical improvements are due to a prolonged, continuous work hardening effect not commonly observed in Ti alloys. 〈em〉In situ〈/em〉 x-ray diffraction and high resolution digital image correlation are used to examine the strain partitioning between the phases during tensile loading with post-mortem electron microscopy to characterize the deformation behavior in each phase. Specimens heat treated between 850 and 980 °C were tested and the effect of annealing temperature on the micromechanical response is discussed. It is shown that the work hardening is the result of composite load-sharing behavior between three mechanically distinct microstructures: large 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉α〈/mi〉〈/mrow〉〈/math〉 lamellae and a martensitic region of fine acicular 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mi〉α〈/mi〉〈mo〉'〈/mo〉〈/mrow〉〈/math〉 and a third phase not previously reported in this alloy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930549X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Charlette M. Grigorian, Timothy J. Rupert〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Building on the recent discovery of tough nanocrystalline Cu-Zr alloys with amorphous intergranular films, this paper investigates ternary nanocrystalline Cu-Zr-Hf alloys with a focus on understanding how alloy composition affects the formation of disordered complexions. Binary Cu-Zr and Cu–Hf alloys with similar initial grain sizes were also fabricated for comparison. The thermal stability of the nanocrystalline alloys was evaluated by annealing at 950 °C (〉95% of the solidus temperatures), followed by detailed characterization of the grain boundary structure. All of the ternary alloys exhibited exceptional thermal stability comparable to that of the binary Cu-Zr alloy, and remained nanocrystalline even after two weeks of annealing at this extremely high temperature. Despite carbide formation and growth in these alloys during milling and annealing, the thermal stability of the ternary alloys is mainly attributed to the formation of thick amorphous intergranular films at high temperatures. Our results show that ternary alloy compositions have thicker boundary films compared to the binary alloys with similar global dopant concentrations. While it is not required for amorphous complexion formation, this work shows that having at least three elements present at the interface can lead to thicker grain boundary films, which is expected to maximize the previously reported toughening effect.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305439-fx1.jpg" width="400" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Hao Fu, Chongchong Miao, Yuanpeng Rui, Fenglin Hu, Ming Shen, Hong Xu, Chunfu Zhang, Yi Dong, Wenping Wang, Hongchen Gu, Yourong Duan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Polyelectrolyte modified iron oxide nanoparticles have great potential applications for clinical magnetic resonance imaging (MRI) and anemia treatments, however, possible associated heart toxicity is rarely reported. Here, polyacrylic acid (PAA)-coated Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles (PION) were synthesized and lethal reactions appeared when it was applied 〈em〉in vivo〈/em〉. The investigation of underlying mechanism showed that PION could break electrolyte balance and further resulted in serious heart failure, which was observed under color doppler ultrasound and dynamic vector blood flow technique. The results demonstrated that PION had a strong absorption tendency for divalent ions and the maximum tolerated dose (MTD) was lower than 100 mg/kg. From electrocardiography (ECG), PION presented an obvious impact on CaV〈sub〉1.2〈/sub〉 ion channel, which leading to fatal arrhythmia. An appropriate solution for preventing this deadly effect was pre-adding Ca〈sup〉2+〈/sup〉 (n 〈sub〉(Ca〈/sub〉〈sup〉2+〈/sup〉〈sub〉)〈/sub〉: n 〈sub〉(COOH)〈/sub〉 = 3: 8) to PION (PION-Ca), which displayed much higher cardiac and electrophysiological safety when sealing the binding point of divalent cation ions with PAA. The injection in Beagle dogs further confirmed the safety of PION-Ca. This study explored the mechanism and offered a solution for cardiac toxicity induced by PAA-coated nanoparticles, which guides for enhancing the safety of such polyelectrolyte decorated nanoparticles and provides assurance for clinical applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Hangfeng Zhang, Bin Yang, Haixue Yan, Isaac Abrahams〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Switchable ferroelectric/antiferroelectric ceramics are of significant interest for high power energy storage applications. Grain size control of this switching is an interesting approach to controlling polarization and hence dielectric properties. However, the use of this approach in technologically relevant ceramics is hindered by difficulty in fabricating dense ceramics with small grain sizes. Here an intermediate polar ferroelectric phase (〈em〉P〈/em〉2〈sub〉1〈/sub〉〈em〉ma〈/em〉) has been isolated in dense bulk sodium niobate ceramics by grain size control through spark plasma sintering methods. Our findings, supported by XRD, DSC, P-E (I-E) loops and dielectric characterization, provide evidence that the phase transition from the antiferroelectric (AFE) R-phase, in space group 〈em〉Pnmm〈/em〉, above 300 °C, to the AFE P-phase, in space group 〈em〉Pbma〈/em〉, at room temperature, always involves the polar intermediate 〈em〉P〈/em〉2〈sub〉1〈/sub〉〈em〉ma〈/em〉 phase and that the 〈em〉P〈/em〉2〈sub〉1〈/sub〉〈em〉ma → Pbma〈/em〉 transition can be suppressed by reducing grain size.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305506-fx1.jpg" width="296" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): M.J. Konstantinović, I. Uytdenhouwen, G. Bonny, N. Castin, L. Malerba, P. Efsing〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thermal stability and the structure of solute-vacancy clusters formed by neutron irradiation are studied by means of positron annihilation spectroscopy and hardness measurements of post-irradiation annealed reactor pressure vessel steels with high and low Ni contents. Two distinct recovery stages were observed and assigned to (a) the dissolution of vacancy clusters at about 650 K, and (b) the dissolution of solute-vacancy clusters at about 750 K. In steels with high Ni content, hardening mainly recovers during the second stage. Atomistic and coarse grain models suggest that during this stage, the removal of vacancies from vacancy-solute clusters leads to complete cluster dissolution, which indicates that solute clusters are radiation induced.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305403-fx1.jpg" width="280" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Hui Chen, Qingsong Wei, Yingjie Zhang, Fan Chen, Yusheng Shi, Wentao Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The packing density of the powder layer plays a key role in the final quality of the parts fabricated via powder-bed-based (PBB) additive manufacturing. This paper presents a combined experimental and computational modeling study on the scraping type of powder-spreading process, in order to understand the fundamental mechanisms of the packing of the powder layer. The deposition mechanisms at the particulate scale, including particle contact stress and particle velocity, are investigated, using the discrete element method, while the macro-scale packing density is validated by experiments. It is found that there is a stress-dip at the bottom of powder pile scraped by the rake. This stress-dip makes the powder particles uniformly deposited. Three kinds of deposition mechanisms dominating the powder-spreading process are identified: cohesion effect, wall effect, and percolation effect. The cohesion effect, which leads to particle agglomerations and thus reduces the packing density, becomes stronger with the decrease of particle size. The wall effect, which leads to more vacancies in the powder layer, becomes stronger with the decrease of layer thickness or the increase of particle size. The percolation effect exists in bimodal powder particles, which leads to particle segregation within the powder layer and thus reduces the packing density. The three kinds of deposition mechanisms compete with each other during the powder-spreading process and make combined effects on the packing density of the powder layer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305427-fx1.jpg" width="264" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Qi-Nan Han, Shao-Shi Rui, Wenhui Qiu, Xianfeng Ma, Yue Su, Haitao Cui, Hongjian Zhang, Huiji Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of crystal orientation on fretting fatigue induced crack initiation and dislocation distribution is studied by in-situ SEM observation and electron back-scattered diffraction (EBSD) in this paper. Cracks and slip lines are observed in the fretting contact area of Ni-based single-crystal (NBSX) superalloys. The in-situ SEM observation captures different crack and slip line behaviors under different crystal orientations. The EBSD analysis results show obvious misorientation and orientation deviation in the fretting contact area. For both crystal orientations, the geometrically necessary dislocation (GND) density distributions in the contact area are obtained by using Hough-based EBSD methods. The peak position of grain reference orientation deviation (GROD) and GND density matches with the fretting fatigue crack formation position. EBSD analysis shows that the dislocation density distribution on each slip system is closely related to the crack initiation direction. The direction of slip system with the maximum dislocation density agrees with the crack initiation direction obtained by in-situ observation.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305476-fx1.jpg" width="448" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Jinghao Xu, Hans Gruber, Dunyong Deng, Ru Lin Peng, Johan J. Moverare〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Additive manufacturing (AM) of high γ′ strengthened Nickel-base superalloys, such as IN738LC, is of high interest for applications in hot section components for gas turbines. The creep property acts as the critical indicator of component performance under load at elevated temperature. However, it has been widely suggested that the suitable service condition of AM processed IN738LC is not yet fully clear. In order to evaluate the short-term creep behavior, slow strain rate tensile (SSRT) tests were performed. IN738LC bars were built by laser powder-bed-fusion (L-PBF) and then subjected to hot isostatic pressing (HIP) followed by the standard two-step heat treatment. The samples were subjected to SSRT testing at 850 °C under strain rates of 1 × 10〈sup〉−5〈/sup〉/s, 1 × 10〈sup〉−6〈/sup〉/s, and 1 × 10〈sup〉−7〈/sup〉/s. In this research, the underlying creep deformation mechanism of AM processed IN738LC is investigated using the serial sectioning technique, electron backscatter diffraction (EBSD), transmission electron microscopy (TEM). On the creep mechanism of AM polycrystalline IN738LC, grain boundary sliding is predominant. However, due to the interlock feature of grain boundaries in AM processed IN738LC, the grain structure retains its integrity after deformation. The dislocation motion acts as the major accommodation process of grain boundary sliding. Dislocations bypass the γ′ precipitates by Orowan looping and wavy slip. The rearrangement of screw dislocations is responsible for the formation of subgrains within the grain interior. This research elucidates the short-creep behavior of AM processed IN738LC. It also shed new light on the creep deformation mechanism of additive manufactured γ′ strengthened polycrystalline Nickel-base superalloys.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305464-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Garth C. Egan, Tae Wook Heo, Amit Samanta, Geoffrey H. Campbell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report a novel mechanism for explosive crystallization in amorphous germanium (a-Ge), which operates through liquid-mediated nucleation occurring under extreme thermal gradient conditions. The crystallization kinetics of sputter-deposited films with thicknesses ranging from 30 to 150 nm were characterized using 〈em〉in situ〈/em〉 movie-mode dynamic transmission electron microscopy (MM-DTEM). After localized heating from a short laser pulse, explosive liquid phase nucleation (LPN) was observed to occur during the early stage (〈2 μs) of crystallization in the thicker (〉50 nm) films deposited on silicon nitride substrates. The crystallization front propagated at ∼12–15 m/s and produced nanocrystalline microstructure with ∼50 nm grains. A mechanism involving the existence of a relatively thick (〉100 nm) transient liquid layer and a high nucleation rate is proposed to explain the behavior. The key thermodynamic and kinetic features as well as the feasibility of the mechanism are further explored by employing parametric and systematic phase-field modeling and simulations.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305385-fx1.jpg" width="418" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): J. Daniel Griffin, Jimmy Y. Song, Aric Huang, Alexander R. Sedlacek, Kaitlin L. Flannagan, Cory J. Berkland〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Relapsing-remitting patterns of many autoimmune diseases such as multiple sclerosis (MS) are perpetuated by a recurring circuit of adaptive immune cells that amplify in secondary lymphoid organs (SLOs) and traffic to compartments where antigen is abundant to elicit damage. Some of the most effective immunotherapies impede the migration of immune cells through this circuit, however, broadly suppressing immune cell migration can introduce life-threatening risks for patients. We developed antigen-specific immune decoys (ASIDs) to mimic tissues targeted in autoimmunity and selectively intercept autoimmune cells to preserve host tissue. Using Experimental Autoimmune Encephalomyelitis (EAE) as a model, we conjugated autoantigen PLP〈sub〉139-151〈/sub〉 to a microporous collagen scaffold. By subcutaneously implanting ASIDs after induction but prior to the onset of symptoms, mice were protected from paralysis. ASID implants were rich with autoimmune cells, however, reactivity to cognate antigen was substantially diminished and apoptosis was prevalent. ASID-implanted mice consistently exhibited engorged spleens when disease normally peaked. In addition, splenocyte antigen-presenting cells were highly activated in response to PLP rechallenge, but CD3〈sup〉+〈/sup〉 and CD19 〈sup〉+〈/sup〉 effector subsets were significantly decreased, suggesting exhaustion. ASID-implanted mice never developed EAE relapse symptoms even though the ASID material had long since degraded, suggesting exhausted autoimmune cells did not recover functionality. Together, data suggested ASIDs were able to sequester and exhaust immune cells in an antigen-specific fashion, thus offering a compelling approach to inhibit the migration circuit underlying autoimmunity.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Le Van Lich, Minh-Tien Le, Tinh Quoc Bui, Thanh-Tung Nguyen, Takahiro Shimada, Takayuki Kitamura, Trong-Giang Nguyen, Van-Hai Dinh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A reversal of polarization vortexlike domains in ferroelectric nanostructures plays important roles for next generations of electronic nanodevices. However, a direct switching of the polarization vortexlike domains in ferroelectrics is a nontrivial task since the toroidal moment is conjugated to a curled electric field rather than a homogeneous one. This work is dedicated to developing an approach to directly switch the toroidal ordering under an irrotational (homogeneous) electric field with the use of compositionally graded ferroelectric (cgFE) nanodots. The variation in material compositions induces an additionally broken spatial inversion symmetry at a scale beyond unit-cell level, giving rise to a formation of asymmetric flux-closure domain (FCD) in a cgFE nanodot. More interestingly, such an asymmetric character facilitates to a switch of FCD by an irrotational electric field. In particular, the rotation of polarization can be directly switched from counter-clockwise to clockwise rotations and vice versa without a formation of intermediate domain structures during the switching process. This switching behavior is distinguished from that in homogeneous counterparts. We further demonstrate that the variation in material compositions tailors the distributions of electrostatic and total free energies in the cgFE nanodot that can control the annihilation/initiation process of FCD under irrotational electric field, providing fundamental reason for the direct switching of the toroidal moment. Another interesting issue is found that both the amplitude and frequency of applied electric field strongly affect the switching behavior of FCD in cgFE nanodot.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305373-fx1.jpg" width="459" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Jiang Wu, Anqi Chen, Yajiao Zhou, Sen Zheng, Yao Yang, Ying An, Ke Xu, Huacheng He, Jianming Kang, Jittima Amie Luckanagul, Ming Xian, Jian Xiao, Qian Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen sulfide (H〈sub〉2〈/sub〉S), as a gaseous messenger, exhibits potential therapeutic effects in biological and clinical applications. Herein, an 〈em〉in situ〈/em〉 forming biomimetic hyaluronic acid (HA) hydrogel was used as a matrix to dope a pH-controllable H〈sub〉2〈/sub〉S donor, JK1, to form a novel HA-JK1 hybrid system. This HA-JK1 hydrogel was designed as an ideal delivery scaffold for JK1 with pH-dependent prolonged H〈sub〉2〈/sub〉S releasing profile. 〈em〉In vitro〈/em〉 study suggested that JK1 could induce the polarization of M2 phenotype indicating a higher pro-healing efficiency of macrophages. The 〈em〉in vivo〈/em〉 studies on dermal wounds showed that the HA-JK1 hybrid hydrogel significantly accelerated the wound regeneration process through enhanced re-epithelialization, collagen deposition, angiogenesis and cell proliferation. Furthermore, the 〈em〉in vivo〈/em〉 results also demonstrated a higher level of M2 polarization in HA-JK1 treated group with reduced inflammation and improved wound remodeling effects, which was consistent with the 〈em〉in vitro〈/em〉 results. These observations could be considered as a key to the efficient wound treatment. Therefore, we suggest that HA-JK1 can be used as a novel wound dressing material toward cutaneous wound model 〈em〉in vivo〈/em〉. This system should significantly enhance wound regeneration through the release of H〈sub〉2〈/sub〉S that induces the expression of M2 macrophage phenotype.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219304971-fx1.jpg" width="363" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Dipak Kumar Khatua, Anupam Mishra, Naveen Kumar, Gobinda Das Adhikary, Uma Shankar, Bhaskar Majumdar, Rajeev Ranjan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Driven by environmental concerns and governmental directives, a sustained research effort in the last decade and half has led to the development of lead-free alternatives which can potentially replace the commercial lead-based piezoceramics in niche applications. Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 (NBT)-based lead-free piezoceramics have found acceptance as promising lead-free transducers in high power ultrasonic devices. An issue of concern however is the low depolarization temperature which limits the device's tolerance for temperature rise during operation. While several strategies have been reported to improve thermal depolarization in NBT-based piezoceramics, there is a lack of consensus regarding the most fundamental factor/mechanism which enhances the depolarization temperature. In this paper we unravel a coupled microstructural-structural mechanism which controls the thermal depolarization in NBT-based piezoceramics. First, we demonstrate the phenomenon of a considerable increase in the depolarization temperature, without significantly losing the piezoelectric property in unmodified NBT by increasing the grain size. We then establish a grain size controlled structural mechanism and demonstrate that the rise in depolarization temperature is primarily associated with the bigger grains allowing relatively large lattice distortion to develop in the poling stabilized long range ferroelectric phase. We reconfirmed the validity of this mechanism in the model morphotropic phase boundary (MPB) composition 0.94Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉-0.06BaTiO〈sub〉3〈/sub〉. For the sake of generalization, we demonstrate that the same mechanism is operative in another lead-based relaxor-ferroelectric system 0.62PbTiO〈sub〉3〈/sub〉-0.38Bi(Ni〈sub〉0.5〈/sub〉Hf〈sub〉0.5〈/sub〉)O〈sub〉3〈/sub〉. Our study provides the fundamental structural basis for understanding thermal depolarization delay in relaxor ferroelectric based piezoceramics.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305348-fx1.jpg" width="240" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Ian A. Marozas, Kristi S. Anseth, Justin J. Cooper-White〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cells are capable of sensing the differences in elastic and viscous properties (i.e., the ‘viscoelasticity’) of their tissue microenvironment and responding accordingly by changing their transcriptional activity and modifying their behaviors. When designing viscoelastic materials to mimic the mechanical properties of native tissue niches, it is important to consider the timescales over which cells probe their microenvironment, as the response of a viscoelastic material to an imposed stress or strain is timescale dependent. Although the timescale of cellular mechano-sensing is currently unknown, hydrogel substrates with tunable viscoelastic spectra can allow one to probe the cellular response to timescale dependent mechanical properties. Here, we report on a cytocompatible and viscoelastic hydrogel culture system with reversible boronate ester cross-links, formed from pendant boronic acid and vicinal diol moieties, where the equilibrium kinetics of esterification were leveraged to tune the viscoelastic spectrum. We found that viscoelasticity increased as a function of the boronic acid and vicinal diol concentration, and also increased with decreasing cross-linker concentration, where the maximal loss tangent achieved with this system was 0.55 at 0.1 rad s〈sup〉−1〈/sup〉. Additionally, we found that the 〈em〉cis〈/em〉-vicinal diols configuration altered the viscoelastic spectra, where a tan δ peak occurred at ∼1 rad s〈sup〉−1〈/sup〉 for hydrogels functionalized with boronic acid, while an additional peak formed at ≥10 rad s〈sup〉−1〈/sup〉 for hydrogels functionalized with both boronic acid and 〈em〉cis-vic〈/em〉-diols. In experiments with NIH-3T3 fibroblasts cultured on these hydrogels, the projected cell area and nuclear area, focal adhesion tension, and subcellular localization of YAP/TAZ were all found to be lower for cells cultured on the viscoelastic hydrogels compared to elastic hydrogels with a similar storage modulus. Despite these differences, there was not a statistically significant relationship between the frequency dependent viscoelastic material properties characterized in this study and cellular morphologies, focal adhesion tension, or the subcellular localization of YAP. While these results demonstrate that mechanotransduction pathways are affected by viscoelasticity, they also suggest that these mechanotransduction pathways are not particularly sensitive to the frequency dependent viscoelastic material properties from 0.1 to 10 rad s〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Yi Hu, Ting Liu, Jingxia Li, Fengyi Mai, Jiawei Li, Yan Chen, Yanyun Jing, Xin Dong, Li Lin, Junyi He, Yan Xu, Changliang Shan, Jianlei Hao, Zhinan Yin, Tianfeng Chen, Yangzhe Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Immune cell therapy presents a paradigm for the treatment of malignant tumors. Human Vγ9Vδ2 T cells, a subset of peripheral γδ T cells, have been shown to have promising anti-tumor activity. However, new methodology on how to achieve a stronger anti-tumor activity of Vγ9Vδ2 T cells is under continuous investigation. In this work, we used selenium nanoparticles (SeNPs) to strengthen the anti-tumor cytotoxicity of Vγ9Vδ2 T cells. We found SeNPs pretreated γδ T cells had significantly stronger cancer killing and tumor growth inhibition efficacy when compared with γδ T cells alone. Simultaneously, SeNPs pretreatment could significantly upregulate the expression of cytotoxicity related molecules including NKG2D, CD16, and IFN-γ, meanwhile, downregulate PD-1 expression of γδ T cells. Importantly, we observed that SeNPs promoted tubulin acetylation modification in γδ T cells through interaction between microtubule network and lysosomes since the latter is the primary resident station of SeNPs shown by confocal visualization. In conclusion, SeNPs could significantly potentiate anti-tumor cytotoxicity of Vγ9Vδ2 T cells, and both cytotoxicity related molecules and tubulin acetylation were involved in fine-tuning γδ T cell toxicity against cancer cells. Our present work demonstrated a new strategy for further enhancing anti-tumor cytotoxicity of human Vγ9Vδ2 T cells by using SeNPs-based nanotechnology, not gene modification, implicating SeNPs-based nanotechnology had a promising clinical perspective in the γδ T cell immunotherapy for malignant tumors.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Ji Young Park, Jiyou Han, Hyo Sung Jung, Gyunggyu Lee, Hyo Jin Kim, Gun-Sik Cho, Han-Jin Park, Choongseong Han, Jong Seung Kim, Jong-Hoon Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hepatocytes derived from human pluripotent stem cells (hPSCs) are promising candidates for cell therapy and drug discovery. However, it remains challenging to efficiently purify hepatocytes from undesired cell types after differentiation and to accurately monitor grafted cells after transplantation. Indocyanine Green (ICG), an FDA-approved, near-infrared (NIR) dye, has been used for various clinical purposes and is exclusively taken up by hepatocytes. However, ICG has a long emission wavelength (λ〈sub〉em〈/sub〉 〉 800 nm) that is beyond the detection range of fluorescence-activated cell sorting (FACS) systems. Moreover, it is easily eliminated from hepatocytes, hindering its application for NIR imaging. Here, we designed and synthesized two different probes based on the properties of ICG; 1) hepatocyte purifying agent (〈strong〉HPA,〈/strong〉 λ〈sub〉em〈/sub〉 = 562 nm) for 〈em〉in vitro〈/em〉 sorting and 2) hepatocyte imaging agent (〈strong〉HIA,〈/strong〉 λ〈sub〉em〈/sub〉 = 817 nm) for efficient 〈em〉in vivo〈/em〉 NIR imaging. We obtained highly enriched populations of hPSC-derived hepatocytes (hPSC-Heps) from various hPSC lines using HPA probe-based FACS purification. In addition, HIA labelling and NIR imaging allowed the direct visualization and tracking of grafted hPSC-Heps in animals with liver injuries. These results demonstrated that these two probes could be used as powerful tools with hPSC-Heps in both cell replacement therapy and drug screening.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Hao Sun, Shaohua Fu, Chichi Chen, Zhirui Wang, Chandra Veer Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nickel carbonyl vapor deposition (CVD) is a high-efficiency process used to produce nickel shell molds with high yield strength, reasonable ductility, and strong corrosion resistance. Such advantageous properties arise from the nanocrystals and nanotwins inside CVD nickel. However, the nanotwins do not persist at high temperatures, transforming into dislocation cells after 40-min annealing at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉800〈/mn〉〈mspace width="0.25em"〉〈/mspace〉〈mo〉°C〈/mo〉〈/mrow〉〈/math〉. Using experimental examinations and computational simulations, we investigated the kinetics of the annealing-induced detwinning in CVD nickel. TEM examinations showed that detwinning is realized by incoherent twin boundary (ITB) migration; meanwhile, plentiful dislocations are generated from coherent twin boundaries (CTBs). Our theoretical analysis revealed that these dislocations are necessary for the formation of the ITBs. Next, using molecular dynamics simulations, we found that the dislocations nucleated from CTBs during annealing are intrinsic grain boundary dislocations (IGBDs). Driven by the internal stress intensified by grain growth in the nanocrystalline regime, the IGBDs can separate from CTBs due to creep at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉800〈/mn〉〈mspace width="0.25em"〉〈/mspace〉〈mo〉°C〈/mo〉〈/mrow〉〈/math〉, resulting in a higher dislocation density inside the twin lamella than that of the outside. These dislocations can trigger the formation of ITBs. Overall, unlike grain growth, stress is necessary for detwinning, so a monolithic nanotwin structure should be more stable than the nanotwins inside a nanocrystalline matrix.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305208-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Zefeng Yu, Chenyu Zhang, Paul M. Voyles, Lingfeng He, Xiang Liu, Kelly Nygren, Adrien Couet〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Proton irradiation induced Nb redistribution in Zr-xNb alloys (x = 0.4, 0.5, 1.0 wt%) has been investigated using scanning transmission electron microscopy/energy dispersive X-ray spectroscopy (STEM/EDS). Zr-xNb alloys are mainly composed of Zr matrix, native Zr–Nb–Fe phases, and β-Nb precipitates. After 2 MeV proton irradiation at 350 °C, a decrease of Nb content in native precipitates, as well as irradiation-induced precipitation of Nb-rich platelets (135 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo〉±〈/mo〉〈/mrow〉〈/math〉 69 nm long and 27 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo〉±〈/mo〉〈/mrow〉〈/math〉 12 nm wide) were found. Nb-rich platelets and Zr matrix form the Burgers orientation relationship, [〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mn〉1〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉1〈/mn〉〈/mrow〉〈/math〉]//[〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mn〉2〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈/math〉] and (011)//(0002). The platelets were found to be mostly coherent with the matrix with a few dislocations near the ends of the precipitate. The coherent strain field has been measured in the matrix and platelets by the 4D-STEM technique. The growth of Nb-rich platelets is mainly driven by coherency and dislocation-induced strain fields. Irradiation may both enhance the diffusion and induce segregation of interstitial Nb to the ends of the irradiation induced platelets, further facilitating their growth.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305221-fx1.jpg" width="250" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Gi-Dong Sim, Kelvin Y. Xie, Kevin J. Hemker, Jaafar A. El-Awady〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here, an experimental study utilizing 〈em〉in-situ〈/em〉 scanning electron microscopy (SEM) micro-compression testing and post-mortem transmission electron microscopy (TEM) imaging is presented to quantify the effect of temperature on the transition in deformation modes in twin-oriented Mg single crystals. Single crystal micropillars were fabricated using FIB milling, then tested by 〈em〉in-situ〈/em〉 SEM micro-compression from 20 °C to 225 °C. It is observed that plasticity in the deformed Mg microcrystals at temperatures at and below 100 °C is governed by 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mn〉10〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉2〈/mn〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈/math〉 extension twinning. However, an anomalous increase of the flow stresses is observed at 100 °C, which is likely due to paucity of dislocation sources that are required to promote twin boundary migration. At 150 °C and above, extension twinning is suppressed and a continuous plastic flow and strain softening induced by prismatic dislocation mediated plasticity is observed. By comparing the current results with those from bulk scale studies for other hexagonal-closed-pack single crystals (e.g. titanium (Ti) and zirconium (Zr)), a general trend for the effect of temperature on the transition in deformation modes in HCP materials is proposed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305245-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): X.C. Tang, C. Li, H.Y. Li, X.H. Xiao, L. Lu, X.H. Yao, S.N. Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A special spallation morphology in bulk metallic glass, named as the “cup-cone” structure, is of particular interest since it manifests a unique “ductile–brittle” transition. To gain insights into the underlying mechanism for the formation of a cup-cone structure, we conduct planar impact experiments at various impact velocities, as well as finite element method analysis. Spall strength increases with increasing impact velocity. Scanning electron microscopy and X-ray computed tomography are performed on postmortem samples to characterize cup-cone structures; their average size and spacing decrease as impact velocity increases, and they dominate fracture morphology at high impact velocities. Cups and cones are generally distributed on the side away from and on the side closer to the target free surface, respectively. The initial nucleation sites of voids become the conical vertices of cup-cones, and the subsequent nucleation sites form along the conical surface and coalesce into the cracks and fracture surfaces.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305087-fx1.jpg" width="287" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Satoshi Okamoto, Kazunori Miyazawa, Takahiro Yomogita, Nobuaki Kikuchi, Osamu Kitakami, Kentaro Toyoki, David Billington, Yoshinori Kotani, Tetsuya Nakamura, Taisuke Sasaki, Tadakatsu Ohkubo, Kazuhiro Hono, Yukio Takada, Takashi Sato, Yuji Kaneko, Akira Kato〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Ga-doped Nd-Fe-B sintered magnet has attracted significant attention as a heavy-rare-earth-free high-performance magnet. We have studied the temperature dependent magnetization reversal process of a Ga-doped Nd-Fe-B sintered magnet based on the first-order reversal curve (FORC) analysis. The FORC diagram pattern of the Ga-doped Nd-Fe-B sintered magnet changes from single spot in the high field region at room temperature to double spots in the low and high field regions at 200 °C, indicating that the dominant magnetization reversal process changes from single domain type to multidomain type. The single domain magnetization reversal at room temperature is well confirmed by using the soft X-ray magnetic circular dichroism microscopy observation. This change in the magnetization reversal process is well discussed by the temperature dependent local demagnetization field and the saturation field of multidomain state. Moreover, we have demonstrated the quantitative analysis of the FORC diagram pattern, which makes a deeper understanding of the magnetization reversal process of the Ga-doped Nd-Fe-B sintered magnet.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305063-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Dian R. Arifin, Mangesh Kulkarni, Deepak Kadayakkara, Jeff W.M. Bulte〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Clinical trials that have used encapsulated islet cell therapy have been few and overall disappointing. This is due in part to the lack of suitable methods to monitor the integrity vs. rupture of transplanted microcapsules over time. Fluorocapsules were synthesized by embedding emulsions of perfluoro-15-crown-5-ether (PFC), a bioinert compound detectable by 〈sup〉19〈/sup〉F MRI, into dual-alginate layer, Ba〈sup〉2+〈/sup〉-gelled alginate microcapsules. Fluorocapsules were spherical with an apparent smooth surface and an average diameter of 428 ± 52 μm. After transplantation into mice, the 〈sup〉19〈/sup〉F MRI signal of capsules remained stable for up to 90 days, corresponding to the total number of intact fluorocapsules. When single-alginate layer capsules were ruptured with alginate lyase, the 〈sup〉19〈/sup〉F MRI signal dissipated within 4 days. For fluoroencapsulated luciferase-expressing mouse βTC6 insulinoma cells implanted into autoimmune NOD/ShiLtJ mice and subjected to alginate-lyase induced capsule rupture 〈em〉in vivo〈/em〉, the 〈sup〉19〈/sup〉F MRI signal decreased sharply over time along with a decrease in bioluminescence imaging signal used as a measure of cell viability 〈em〉in vivo〈/em〉. These results indicate that maintenance of capsule integrity is essential for preserving transplanted cell survival, where a decrease in 〈sup〉19〈/sup〉F MRI signal may serve as a predictive imaging surrogate biomarker for impending failure of encapsulated islet cell therapy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Caption: When weak implanted immunoprotective fluorocapsules are ruptured in vivo, the 〈sup〉19〈/sup〉F MRI signal disappears rapidly. In contrast, the signal of strong, intact fluorocapsules remains unchanged. This dissipation of 〈sup〉19〈/sup〉F MRI signal may be used as a surrogate imaging biomarker for loss of immunoprotection and impending failure of encapsulated cell therapy.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305095-egi10491Q07482.jpg" width="255" alt="Image 1049107482" title="Image 1049107482"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Sumeet Mishra, Manasij Yadava, Kaustubh N. Kulkarni, N.P. Gurao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new methodology for analyzing strain hardening behavior of face centered cubic materials based on transition from restricted glide/single slip to multiple slip has been developed. The proposed modification considers strain dependence of orientation factor spanning between lower bound iso-stress Sachs model and upper bound iso-strain Taylor model. The modifications are suitably incorporated in the classical two internal variable model to develop a new slip activity based strain hardening model. The proposed model is shown to be performing better than the existing one parameter forest strengthening model and two internal variable model in predicting strain hardening behavior in the presence of wide range of microstructural features such as solutes, semi-coherent and incoherent precipitates, grain sizeand twins. Experimental validation of the proposed concept of transition in slip behavior is shown in terms of evolution of dislocation density and character from X-ray diffraction and surface roughness, slip lines and micro-texture from in-situ electron back scatter diffraction tests.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930504X-fx1.jpg" width="257" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): B. Christiaen, C. Domain, L. Thuinet, A. Ambard, A. Legris〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The growth of zirconium alloys under irradiation is a phenomenon experimentally identified and associated with the development beyond a threshold dose of dislocation loops with vacancy character having a Burgers vector with a component parallel to the c axis. In this work, by combining atomic simulations (DFT and empirical potential) and continuous modeling, we show that prismatic stacking fault pyramids or bipyramids whose base rests on the basal plane of the hcp structure are likely precursors to the formation of ‹c› vacancy loops. In other words, these would not be formed by progressive accretion of vacancies but rather by collapse of the pyramids or bipyramids beyond a certain size. This mechanism could explain the fact that the ‹c› vacancy loops are never observed below a size of the order of 10 nm and their appearance at high fluence.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304707-fx1.jpg" width="389" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): P.E. Seiler, H.C. Tankasala, N.A. Fleck〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Additive manufacture and rapid prototyping are versatile methods for the generation of lattice materials for applications in the creep regime. However, these techniques introduce defects that can degrade the macroscopic creep strength. In the present study, the uniaxial tensile response of two-dimensional PMMA lattices is measured in the visco-plastic regime: tests are performed at 100 °C which is slightly below the glass transition temperature 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mtext〉g〈/mtext〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 of PMMA. Both 〈em〉as-manufactured〈/em〉 defects (Plateau borders and strut thickness variation) and 〈em〉as-designed〈/em〉 defects (missing cell walls, solid inclusions, and randomly perturbed joints) are introduced. The dispersion in macroscopic strength is measured for relative densities in the range of 0.07–0.19. It is observed that initial failure of the lattice is diffuse in nature: struts fail at a number of uncorrelated locations, followed by the development of a single macroscopic crack transverse to the loading direction. In contrast, the same PMMA lattice fails in a correlated, brittle manner at room temperature. An FE study is performed to gain insight into the diffuse failure mode and the role played by 〈em〉as-manufactured〈/em〉 defects, including the dispersion in tensile strength of individual struts of the lattice. A high damage tolerance to 〈em〉as-designed〈/em〉 defects is observed experimentally: there is negligible knock-down in strength due to the removal of cell walls or to the presence of solid inclusions. These findings aid the design and manufacture of damage tolerant lattices in the creep regime.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Elastic-brittle versus visco-plastic failure ofPMMA lattices.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305026-fx1.jpg" width="229" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 177〈/p〉 〈p〉Author(s): Christopher A. Schuh〈/p〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Dhruvkumar Soni, Aditya N. Bade, Nagsen Gautam, Jonathan Herskovitz, Ibrahim M. Ibrahim, Nathan Smith, Melinda S. Wojtkiewicz, Bhagya Laxmi Dyavar Shetty, Yazen Alnouti, JoEllyn McMillan, Howard E. Gendelman, Benson J. Edagwa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉While antiretroviral therapy (ART) has revolutionized treatment and prevention of human immunodeficiency virus type one (HIV-1) infection, regimen adherence, viral mutations, drug toxicities and access stigma and fatigue are treatment limitations. These have led to new opportunities for the development of long acting (LA) ART including implantable devices and chemical drug modifications. Herein, medicinal and formulation chemistry were used to develop LA prodrug nanoformulations of emtricitabine (FTC). A potent lipophilic FTC phosphoramidate prodrug (M2FTC) was synthesized then encapsulated into a poloxamer surfactant (NM2FTC). These modifications extended the biology, apparent drug half-life and antiretroviral activities of the formulations. NM2FTC demonstrated a 〉30-fold increase in macrophage and CD4+ T cell drug uptake with efficient conversion to triphosphates (FTC-TP). Intracellular FTC-TP protected macrophages against an HIV-1 challenge for 30 days. A single intramuscular injection of NM2FTC, at 45 mg/kg native drug equivalents, into Sprague Dawley rats resulted in sustained prodrug levels in blood, liver, spleen and lymph nodes and FTC-TP in lymph node and spleen cells at one month. In contrast, native FTC-TPs was present for one day. These results are an advance in the transformation of FTC into a LA agent.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): N. Almirall, P.B. Wells, T. Yamamoto, K. Wilford, T. Williams, N. Riddle, G.R. Odette〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mn-Ni-Si intermetallic precipitates (MNSPs) that are observed in some Fe-based alloys following thermal aging and irradiation are of considerable scientific and technical interest. For example, large volume fractions (f) of MNSPs form in reactor pressure vessel low alloy steels irradiated to high fluence, resulting in severe hardening induced embrittlement. Nine compositionally-tailored small heats of low Cu RPV-type steels, with an unusually wide range of dissolved Mn (0.06–1.34 at.%) and Ni (0.19–3.50 at.%) contents, were irradiated at ≈ 290 °C to ≈ 1.4 × 10〈sup〉20〈/sup〉 n/cm〈sup〉2〈/sup〉 at an accelerated test reactor flux of ≈3.6 × 10〈sup〉12〈/sup〉 n/cm〈sup〉2〈/sup〉-s (E 〉 1 MeV). Atom probe tomography shows Mn-Ni interactions play the dominant role in determining the MNSP f, which correlates well with irradiation hardening. The wide range of alloy compositions results in corresponding variations in precipitates chemistries that are reasonably similar to various phases in the Mn-Ni-Si projection of the Fe based quaternary. Notably, f scales with ≈ Ni〈sup〉1.6〈/sup〉Mn〈sup〉0.8〈/sup〉. Thus f is modest even in advanced high 3.5 at.% Ni steels at very low Mn (Mn starvation); in this case Ni-silicide phase type compositions are observed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305397-fx1.jpg" width="415" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Bar Danino, Gil Gur-Arieh, Doron Shilo, Dan Mordehai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferroic materials typically exhibit a microstructure that contains twins or domains separated by twin boundaries (walls). The deformation of these materials is governed by twin boundary motion under mechanical/electrical/magnetic driving force. The Landau-Ginzburg model is a widely accepted phenomenological model used to describe twin boundary properties. However, it is incapable of describing energy barriers for motion due to the lack of atomistic description. In this work, we present a model interatomic potential for studying the relations between the lattice barrier for twin boundary motion and measurable material properties. The interatomic potential emulates the continuum Landau-Ginzburg model and reproduces known results of twin boundary thickness and energy as a function of the model parameters. An atomic model system is constructed, with a single twin boundary separating crystals of different orientations and we employ the Nudged Elastic Band method to calculate the energy barriers for the motion of twin boundaries with different thicknesses under different externally-applied shear stresses. The results are summarized in a closed-form expression relating the energy barriers with material properties and the external loading. The energy barrier function extends the Landau-Ginzburg model and allows treating the motion of twin boundary as a thermally activated process.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305282-fx1.jpg" width="446" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Hongping Li, Mitsuhiro Saito, Chunlin Chen, Kazutoshi Inoue, Kazuto Akagi, Yuichi Ikuhara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metal/oxide heterointerfaces are ubiquitous in functional materials, and their microstructures frequently govern the macroscopic properties. It has been believed that the interfacial interactions are very weak at incoherent interfaces with large mismatches. Combining atomic-resolution scanning transmission electron microscopy with density functional theory calculations, we investigated the interaction and bonding reconstruction at Pd/ZnO{0001} interfaces, which have large mismatches. Molecular beam epitaxy was employed to grow Pd films on clean Zn-terminated ZnO(0001) and O-terminated ZnO(000〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉) polarized surfaces. Atomically sharp Zn-terminated interfaces formed on both substrates, and the large lattice misfits between them were not strongly accommodated, suggesting the formation of incoherent regions. The interfacial atoms were located almost at bulk lattice points in the stoichiometric Zn-terminated Pd(111)/ZnO(0001) structure, whereas the interfacial Pd and Zn atoms underwent relatively large relaxations on the interfacial plane in the nonstoichiometric Zn-terminated Pd(111)/ZnO(〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mn〉000〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mrow〉〈/math〉) interface. Effective Pd–Zn chemical bonds were formed across both interfaces, but the bonding mechanisms were quite different, depending on the local atomic geometry. The Pd–Zn bonds exhibited site-dependent characteristics and gradually transitioned from covalent to ionic at the Pd(111)/ZnO(0001) interface, whereas most of Pd–Zn bonds exhibited strong covalent behavior at the Pd/ZnO(〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mn〉000〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mrow〉〈/math〉) interface. The adhesive energies indicated that the Zn-terminated Pd/ZnO(〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mn〉000〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mrow〉〈/math〉) interface is energetically preferable to the Zn-terminated Pd/ZnO(0001) interface. Thus, the interfacial interaction can be strong and direct metal–metal interactions can play a critical role in metal/oxide heterointerfaces with large mismatches, opening up a new avenue for understanding the origins of interface-related issues.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305300-fx1.jpg" width="344" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Mans Broekgaarden, Sriram Anbil, Anne-Laure Bulin, Girgis Obaid, Zhiming Mai, Yan Baglo, Imran Rizvi, Tayyaba Hasan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The complex interplay between cancer cells and their microenvironment remains a major challenge in the design and optimization of treatment strategies for pancreatic ductal adenocarcinoma (PDAC). Recent investigations have demonstrated that mechanistically distinct combination therapies hold promise for treatment of PDAC, but effective clinical translation requires more accurate models that account for the abundant tumor-stroma and its influence on cancer growth, metabolism and treatment insensitivity. In this study, a modular 3D culture model that comprised PDAC cells and patient-derived cancer-associated fibroblasts (CAFs) was developed to assess the effects of PDAC-CAF interactions on treatment efficacies. Using newly-developed high-throughput imaging and image analysis tools, it was found that CAFs imparted a notable and statistically significant resistance to oxaliplatin chemotherapy and benzoporphyrin derivative-mediated photodynamic therapy, which associated with increased levels of basal oxidative metabolism. Increased treatment resistance and redox states were similarly observed in an orthotopic xenograft model of PDAC in which cancer cells and CAFs were co-implanted in mice. Combination therapies of oxaliplatin and PDT with the mitochondrial complex I inhibitor metformin overcame CAF-induced treatment resistance. The findings underscore that heterotypic microtumor culture models recapitulate metabolic alterations stemming from tumor-stroma interactions. The presented infrastructure can be adapted with disease-specific cell types and is compatible with patient-derived tissues to enable personalized screening and optimization of new metabolism-targeted treatment regimens for pancreatic cancer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305204-fx1.jpg" width="497" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Keita Nomoto, Hiroshi Sugimoto, Xiang-Yuan Cui, Anna V. Ceguerra, Minoru Fujii, Simon P. Ringer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Boron (B) and phosphorous (P) co-doped colloidal silicon nanocrystals (Si NCs) have unique size-dependent optical properties, which lead to potential applications in optoelectronic and biomedical applications. However, the microstructure of the B and P co-doped colloidal Si NCs – in particular, the exact location of the dopant atoms in real space, has not been studied. A lack of understanding of this underlying question limits our ability to better control sample fabrication, as well as our ability to further develop the optical properties. To study the microstructure, a process enabling atom probe tomography (APT) of colloidal Si NCs was developed. A dispersion of colloidal Si NCs in a SiO〈sub〉2〈/sub〉 sol-gel solution and a low temperature curing are demonstrated as the key sample preparation steps. Our APT results demonstrate that a B-rich region exists at the surface of the Si NCs, while P atoms are distributed within the Si NCs. First principles density functional theory calculations of a Si NC embedded in SiO〈sub〉2〈/sub〉 matrix reveal that P atoms, which always prefer to reside inside a Si NC, significantly influence the distribution of B atoms. Specifically, P atoms lower the B diffusion barrier at Si/SiO〈sub〉2〈/sub〉 interface and stabilize B atoms to reside within individual Si NCs. We propose that the B-modified surface changes the chemical properties of the Si NCs by (i) offering chemical resistance to attack by HF and (ii) enabling dispersibility in solution without aggregation.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305233-fx1.jpg" width="205" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Jiahui Peng, Juan Chen, Fang Xie, Wei Bao, Hongyan Xu, Hongxia Wang, Yuhong Xu, Zixiu Du〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have constructed Herceptin-conjugated, paclitaxel (PTX) loaded, PCL-PEG worm-like nanocrystal micelles (PTX@PCL-PEG-Herceptin) for the combinatorial therapy of HER2-positive breast cancer that exploit the specific targeting of Herceptin to HER2-positive breast cancer cells. Firstly, amphiphilic PCL〈sub〉2000〈/sub〉-MPEG〈sub〉2000〈/sub〉 and PCL〈sub〉5000〈/sub〉-PEG〈sub〉2000〈/sub〉-CHO were selected as the optimized matrix to wrap PTX that self-assembled into worm-like micelles with internal nanocrystal structures (PTX@PCL-PEG). Then the aldehydes of PCL〈sub〉5000〈/sub〉-PEG〈sub〉2000〈/sub〉-CHO exposed on the outside surface of PTX@PCL-PEG were utilized to react with the primary amines of Herceptin and formed stable, carbon-nitrogen single linkers (–C–N–) between the antibodies and nanoparticles. This study shows PTX@PCL-PEG-Herceptin remained relatively stable in the circulation and in the tumor microenvironment, and rapidly targeted and entered into the HER2-overexpressing tumor cells while sparing normal tissues from the toxic effects. PTX@PCL-PEG-Herceptin shrank the tumors and prolonged survival time in a SKBR-3-tumor-xenograft, nude mice model more effectively than TAXOL®, PTX@PCL-PEG, Herceptin+TAXOL® and Herceptin+PTX@PCL-PEG. Mechanistic studies showed that PTX@PCL-PEG-Herceptin entered into the HER2-positive tumor cells through the caveolin-mediated pathway. The conjugated Herceptin greatly enhanced the binding ability of the nanoparticle to the targeted SKBR-3 cells. This novel strategy provides a rational and simple antibody-conjugated-nanoparticle platform for the clinical application of combinatorial anticancer treatment.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305198-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Tong Chen, Dong Cen, Zhaohui Ren, Yifan Wang, Xiujun Cai, Jie Huang, Lucy Di Silvio, Xiang Li, Gaorong Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An unpredicted side effect of photothermal therapy (PTT) is agitated by hyperthermia which results in damage to healthy tissue. Developing PTT platforms, enabling effective tumor ablation under mild irradiation conditions, is of wide interest, but challenging. Here, we investigated bismuth crystals embedded silica (Bi@SiO〈sub〉2〈/sub〉) nanoparticles, loaded with an autophagy inhibitor (chloroquine, CQ). It was found that SiO〈sub〉2〈/sub〉 effectively prevented the oxidization of Bi nanocrystals in the physiological environment and could serve as a scatter layer to improve NIR absorption, enabling a high photothermal conversion efficiency (~43%) and excellent photostability. Furthermore, the findings indicated that CQ molecules, delivered intracellularly by the particles, significantly weakened the degradation of autolysosomes by lysosome within the tumor cells, thus inducing suppression effect to autophagy and resistance to photothermia. Both in vitro and in vivo anti-tumor effects were consequently promoted owing to the combined effects enabled by Bi@SiO〈sub〉2〈/sub〉-CQ nanoparticles under mild NIR irradiation conditions. This study demonstrates a potential new PTT platform with superior therapeutic efficacy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305186-fx1.jpg" width="292" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Kwang-Soo Kim, Jun-Hyeok Han, Jung-Hoon Park, Hyung-Keun Kim, Seung Hee Choi, Gyeong Ryeong Kim, Haengseok Song, Hee Jung An, Dong Keun Han, Wooram Park, Kyung-Soon Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recently, natural killer (NK)-based immunotherapy has attracted attention as a next-generation cell-based cancer treatment strategy due to its mild side effects and excellent therapeutic efficacy. Here, we describe multifunctional nanoparticles (MF-NPs) capable of genetically manipulating NK cells and tracking them 〈em〉in vivo〈/em〉 through non-invasive magnetic resonance (MR) and fluorescence optical imaging. The MF-NPs were synthesized with a core-shell structure by conjugation of a cationic polymer labeled with a near-infrared (NIR) fluorescent molecule, with the aid of a polydopamine (PDA) coating layer. When administered to NKs, the MF-NPs exhibited excellent cytocompatibility, efficiently delivered genetic materials into the immune cells, and induced target protein expression. In particular, the MF-NPs could induce the expression of EGFR targeting chimeric antigen receptors (EGFR-CARs) on the NK cell surface, which improved the cells’ anti-cancer cytotoxic effect both 〈em〉in vitro〈/em〉 and 〈em〉in vivo〈/em〉. Finally, when NK cells labeled with MF-NPs were injected into live mice, MF-NP–labeled NK cells could be successfully imaged using fluorescence and MR imaging devices. Our findings indicate that MF-NPs have great potential for application of NK cells, as well as other types of cell therapies involving genetic engineering and 〈em〉in vivo〈/em〉 monitoring of cell trafficking.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Arthur S. Nishikawa, Goro Miyamoto, Tadashi Furuhara, André P. Tschiptschin, Hélio Goldenstein〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The modification of the matrix of ductile cast irons by heat treatments has been of interest of researchers for many years. Among these treatments, in the last years the Quenching & Partitioning (Q&P) process has emerged as a viable way to produce microstructures containing controlled amounts of martensite and retained austenite, providing a good combination of strength and ductility. In this work, the different mechanisms of phase transformations occurring during the Q&P heat treatment applied to a ductile cast iron alloy is investigated. Microsegregation, inherent to cast irons, was analyzed by means of Electron Probe Microanalysis (EPMA). Microstructural characterization was performed with Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD), while kinetics of carbon redistribution and competitive reactions were studied using dilatometry and in situ synchrotron X-ray diffraction. It was found that either transition carbides or cementite precipitate in martensite depending on the partitioning temperature. Despite of carbides precipitation, evidence of carbon partitioning from martensite to austenite was obtained. Formation of bainitic ferrite occurs during the partitioning step, further contributing to carbon enrichment of austenite. The experimental results are compared with a local field model that computes the local kinetics of carbon redistribution by simultaneously considering carbides precipitation and growth of bainitic ferrite. Results showed that kinetics of carbon partitioning from martensite to austenite depends on the carbides free energy. More stable carbides do not dissolve and prevent the escape of carbon from martensite. Fast carbon partitioning occurs by dissolution of less stable carbides, but it is slowed down as growth of bainitic ferrite proceeds. This result is explained by the overlapping of the diffusion fields (soft impingement) of the carbon partitioned from martensite and the carbon rejected from growth of bainitic ferrite.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305038-fx1.jpg" width="346" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): P. Tozman, Y.K. Takahashi, H. Sepehri-Amin, D. Ogawa, S. Hirosawa, K. Hono〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zr is one of the essential elements to stabilize the ThMn〈sub〉12〈/sub〉 structure in rare earth (R) transition metal (M) hard magnetic compounds, RM〈sub〉12〈/sub〉. In this work, the effects of Zr on the intrinsic hard magnetic properties of (Sm〈sub〉1-x〈/sub〉 Zr〈sub〉x〈/sub〉)(Fe〈sub〉0.8〈/sub〉Co〈sub〉0.2〈/sub〉)〈sub〉12〈/sub〉 compounds are investigated using epitaxially grown thin films. The increase of Zr substitution for Sm from 〈em〉x〈/em〉 = 0 to 0.26 for (Sm〈sub〉1-x〈/sub〉 Zr〈sub〉x〈/sub〉)(Fe〈sub〉0.8〈/sub〉Co〈sub〉0.2〈/sub〉)〈sub〉12〈/sub〉 increases saturation magnetization (μ〈sub〉0〈/sub〉〈em〉M〈/em〉〈sub〉s〈/sub〉) from 1.78 T to 1.90 T, the highest value reported for hard magnetic compounds. The largest μ〈sub〉0〈/sub〉〈em〉H〈/em〉〈sub〉a〈/sub〉 and 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 for Zr-doped samples were found to be 9.8 T and 671 K for 〈em〉x〈/em〉 = 0.18 which is superior to those for Nd〈sub〉2〈/sub〉Fe〈sub〉14〈/sub〉B. Sm-rich Sm〈sub〉1.30〈/sub〉Zr〈sub〉0.27〈/sub〉(Fe〈sub〉0.8〈/sub〉Co〈sub〉0.2〈/sub〉)〈sub〉12,〈/sub〉 obtained as sub-μm thick films, has remanence, μ〈sub〉0〈/sub〉〈em〉M〈/em〉〈sub〉r〈/sub〉 of 1 T, which appears to be useful for near-field applications such as micro-electro-machines and magnetic recording media if microstructure can be optimized to obtain a sufficient coercivity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305051-fx1.jpg" width="441" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 220〈/p〉 〈p〉Author(s): Yidan Wang, Shaoze Song, Tong Lu, Yu Cheng, Yilin Song, Siyu Wang, Fengping Tan, Jiao Li, Nan Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Multifunctional nanoplatforms with flexible architectures and tumor microenvironment response are highly anticipated within the field of thermoradiotherapy. Herein, the multifunctional nanoplatforms for thermoradiotherapy have been successfully constructed by the embedding of tungsten disulfide quantum dots (WS〈sub〉2〈/sub〉 QDs) into mesoporous polydopamine nanosponges (MPDA NSs), followed by integration with manganese dioxide (MnO〈sub〉2〈/sub〉). MPDA-WS〈sub〉2〈/sub〉@MnO〈sub〉2〈/sub〉, the resultant nanoplatforms, exhibit radiosensitization enhanced behavior and a capacity for responsive oxygen self-supplementation. The ingenious mesoporous structure of MPDA NSs serves as reservoir for the assembly of WS〈sub〉2〈/sub〉 QDs to form MPDA-WS〈sub〉2〈/sub〉 nanoparticles (NPs), in which WS〈sub〉2〈/sub〉 QDs provide the radiation enhancement effect, whereas the MPDA NSs framework endows the MPDA-WS〈sub〉2〈/sub〉@MnO〈sub〉2〈/sub〉 with an excellent photothermal capability. Additionally, the integration of the MnO〈sub〉2〈/sub〉 component works to decompose the tumor-overexpressed H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and alleviate tumor hypoxia subsequently, which has been demonstrated to enhance radiotherapy performance considerably. Meanwhile, the prepared MPDA-WS〈sub〉2〈/sub〉@MnO〈sub〉2〈/sub〉 nanoplatforms have been evaluated as trimodality contrast agents for computed tomography (CT), multispectral optoacoustic tomography (MSOT), and tumor microenvironment-responsive T〈sub〉1〈/sub〉-weighted magnetic resonance (MR) imaging that have the potential for real-time guidance and monitoring during cancer therapy. More importantly, when subjected to near infrared (NIR) laser irradiation and X-ray exposure, the tumor is found to be inhibited significantly through the process of combined thermoradiotherapy. The design concepts of embedding WS〈sub〉2〈/sub〉 QDs into MPDA NSs and oxygen self-supplementing hold great potential for multimodal imaging-guided thermoradiotherapy of hypoxic cancer.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 220〈/p〉 〈p〉Author(s): Michelle Maurer, Mark S. Gresnigt, Antonia Last, Tony Wollny, Florian Berlinghof, Rebecca Pospich, Zoltan Cseresnyes, Anna Medyukhina, Katja Graf, Marko Gröger, Martin Raasch, Fatina Siwczak, Sandor Nietzsche, Ilse D. Jacobsen, Marc Thilo Figge, Bernhard Hube, Otmar Huber, Alexander S. Mosig〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Alterations of the microbial composition in the gut and the concomitant dysregulation of the mucosal immune response are associated with the pathogenesis of opportunistic infections, chronic inflammation, and inflammatory bowel disease. To create a platform for the investigation of the underlying mechanisms, we established a three-dimensional microphysiological model of the human intestine. This model resembles organotypic microanatomical structures and includes tissue resident innate immune cells exhibiting features of mucosal macrophages and dendritic cells. The model displays the physiological immune tolerance of the intestinal lumen to microbial-associated molecular patterns and can, therefore, be colonised with living microorganisms. Functional studies on microbial interaction between probiotic 〈em〉Lactobacillus rhamnosus〈/em〉 and the opportunistic pathogen 〈em〉Candida albicans〈/em〉 show that pre-colonization of the intestinal lumen of the model by 〈em〉L. rhamnosus〈/em〉 reduces 〈em〉C. albicans〈/em〉-induced tissue damage, lowers its translocation, and limits fungal burden. We demonstrate that microbial interactions can be efficiently investigated using the 〈em〉in vitro〈/em〉 model creating a more physiological and immunocompetent microenvironment. The intestinal model allows a detailed characterisation of the immune response, microbial pathogenicity mechanisms, and quantification of cellular dysfunction attributed to alterations in the microbial composition.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Baoxiang Tian, Xili Ding, Yang Song, Weicong Chen, Jiaqi Liang, Li Yang, Yubo Fan, Song Li, Yue Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The stiffness change of the vessel wall is involved in many pathological processes of the blood vessel. However, how stiffness changes regulate vascular cell phenotype is not well understood. In this study, we investigated the effects of matrix stiffness on the phenotype and functions of vascular smooth muscle cells (SMCs). SMCs were cultured on the matrices with the stiffness between 1 and 100 kPa. The expression of contractile markers calponin-1 (CNN1) and smoothelin (SMTN) increased with stiffness; in contrast, the expression of synthetic markers osteopontin (OPN) and epiregulin (EREG) were the highest on the soft surface (1 kPa). In addition, matrix metalloproteinase 2 (MMP-2) was significantly upregulated on 1-kPa surface. Consistently, the stiffness of atherosclerotic lesions in human arteries decreased by up to 10 folds compared to normal area (〉40 kPa), which was accompanied by a decrease of CNN1 expression and collagen content and an increase of OPN and MMP-2 in the area of lipid deposition. Furthermore, the phosphorylation of Smad2/3 increased with matrix stiffness; when TGF-β signaling pathway was inhibited, the stiffness effects on the SMCs were reversed. Our findings suggest that matrix stiffness regulates SMC phenotype and matrix remodeling through TGF-β signal pathway. This study unravels a mechanobiological mechanism in vascular remodeling, and will help us develop strategies for vascular tissue engineering, disease modeling and therapies.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 219〈/p〉 〈p〉Author(s): Liewei Wen, Wenzheng Ding, Sihua Yang, Da Xing〈/p〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 220〈/p〉 〈p〉Author(s): Ali Shokoohmand, Jiongyu Ren, Jeremy Baldwin, Anthony Atack, Abbas Shafiee, Christina Theodoropoulos, Marie-Luise Wille, Phong A. Tran, Laura J. Bray, Deborah Smith, Naven Chetty, Pamela M. Pollock, Dietmar W. Hutmacher, Judith A. Clements, Elizabeth D. Williams, Nathalie Bock〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Representative 〈em〉in vitro〈/em〉 models that mimic the native bone tumor microenvironment are warranted to support the development of more successful treatments for bone metastases. Here, we have developed a primary cell 3D model consisting of a human osteoblast-derived tissue-engineered construct (hOTEC) indirectly co-cultured with patient-derived prostate cancer xenografts (PDXs), in order to study molecular interactions in a patient-derived microenvironment context. The engineered biomimetic microenvironment had high mineralization and embedded osteocytes, and supported a high degree of cancer cell osteomimicry at the gene, protein and mineralization levels when co-cultured with prostate cancer PDXs from a lymph node metastasis (LuCaP35) and bone metastasis (BM18) from patients with primary prostate cancer. This fully patient-derived model is a promising tool for the assessment of new molecular mechanisms and as a personalized pre-clinical platform for therapy testing for patients with prostate cancer bone metastases.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 219〈/p〉 〈p〉Author(s): Shengyong Ng, Wai Jin Tan, Michelle Mi Xue Pek, Min-Han Tan, Motoichi Kurisawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Patient-derived tumor organoids offer potentially useful models of cancer tissue physiology. Yet, conventional organoid cultures utilize generic matrices that are difficult to tailor for various unique tumor microenvironments. Here, we employ synthetic, enzymatically crosslinked hydrogels to define mechanical and biochemical properties hypothesized to be relevant for maintaining these organoids. We show that a single extracellular matrix component, gelatin, suffices to support colorectal cancer patient-derived xenograft (CRC-PDX) organoid survival, and that high matrix stiffness synergizes with hypoxia to increase organoid growth and metabolism in a majority of CRC-PDX lines tested. Moreover, we demonstrate that defined gelatin-based hydrogels support CRC-PDX tumor growth 〈em〉in vivo〈/em〉 and organoid sensitivity to various CRC therapeutic drugs 〈em〉in vitro〈/em〉 in a largely comparable fashion to a conventional reconstituted basement membrane matrix. Based on our findings, we propose that enzymatically crosslinked hydrogels potentially provide a platform for designing mechanically and biochemically defined matrices for various types of patient-derived tumor organoids.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): X. Lu, D. Wang, D. Wan, Z.B. Zhang, N. Kheradmand, A. Barnoush〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The susceptibility of age-hardened nickel-based Alloy 718 to hydrogen embrittlement was studied by the controlled electrochemical charging combined with slow strain-rate tensile tests (SSRT) and advanced characterization techniques. We proposed some novel ideas of explaining hydrogen embrittlement mechanisms of the studied material in regard to two cracking morphologies: transgranular and intergranular cracking. It is for the first time to report that electrochemical charging alone could cause slip lines, surface and subsurface cracks on nickel-based superalloys. The formation of pre-damages was discussed by calculating the hydrogen concentration gradient and the internal stress generated during cathodic charging. Pre-damages were proved to result in transgranular cracks and lead to the evident reduction of mechanical properties. In addition, the STRONG (Slip Transfer Resistance of Neighbouring Grains) model was used to analyze the dependence of hydrogen-assisted intergranular cracking on the microscopic incompatibility of the grain boundaries. The results show that in the presence of hydrogen, grain boundaries with a lower dislocation slip transmission are more prone to cracking during loading and vice versa.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305324-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Eiji Saito, Robert Kuo, Kevin R. Kramer, Nishant Gohel, David A. Giles, Bethany B. Moore, Stephen D. Miller, Lonnie D. Shea〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Current therapeutic options for autoimmune diseases, such as multiple sclerosis (MS), often require lifelong treatment with immunosuppressive drugs, yet strategies for antigen specific immunomodulation are emerging. Biodegradable particles loaded with disease specific antigen, either alone or with immunomodulators, have been reported to ameliorate disease. Herein, we hypothesized that the carrier could impact polarization of the immune cells that associate with particles and the subsequent disease progression. Single injection of three polymeric carriers, 50:50 poly (DL-lactide-co-glycolide) (PLG) with two molecular weights (Low, High) and poly (DL-lactide) (PLA), loaded with the disease specific antigen, proteolipid protein (PLP〈sub〉139-151〈/sub〉), were investigated for the ability to attenuate clinical scores in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. At a low particle dose, mice treated with PLA-based particles had significantly lower clinical scores at the chronic stage of the disease over 200 days post immunization, while neither PLG-based particles nor OVA control particles reduced the clinical scores. Compared to PLG-based particles, PLA-based particles were largely associated with Kupffer cells and liver sinusoidal endothelial cells, which had a reduced co-stimulatory molecule expression that correlated with a reduction of CD4〈sup〉+〈/sup〉 T-cell populations in the central nervous system. Delivery of PLA-based particles encapsulated with higher levels of PLP〈sub〉139-151〈/sub〉 at a reduced dose were able to completely ameliorate EAE over 200 days along with inhibition of Th1 and Th17 polarization. Collectively, our study demonstrates that the carrier properties and antigen loading determine phenotypes of immune cells in the peripheral organs, influencing the amelioration of both acute and chronic stages of autoimmunity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305319-fx1.jpg" width="492" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 222〈/p〉 〈p〉Author(s): Charlotte Piard, Anjana Jeyaram, Yi Liu, John Caccamese, Steven M. Jay, Yu Chen, John Fisher〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Vascularization is a crucial process during the growth and development of bone 〈sup〉1〈/sup〉, yet it remains one of the main challenges in the reconstruction of large bone defects. The use of in vitro coculture of human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs) has been one of the most explored options. Both cell types secrete specific growth factors that are mutually beneficial, and studies suggested that cell-cell communication and paracrine secretion could be affected by a number of factors. However, little is known about the effect of cell patterning and the distance between cell populations on their crosstalk. In the present study, we showed that the separation and distance between ECs and MSCs populations affects angiogenesis by modulating cell-cell communication. HUVECs grown farther apart from MSCs (˃400 μm) presented characteristics of an early stage of angiogenesis (migration/proliferation). Results showed an increase in the up-regulation of VEGF, FGF-2, and ITGA3 (integrins) but a smaller fold change in the expression of VE-Cadherin and Ang-1. HUVECs were also still highly proliferative. On the contrary, HUVECs incubated closer (≤200 μm) to MSCs, showed signs of stabilization, mainly an increase in Ang-1 and VE-cadherin expression, as well as tighter monolayers. Conditioned media collected from HUVECs and MSCs grown ≤200 μm apart preferentially promoted tube formation, a later stage of angiogenesis, due in part to a significant increase in Ang-1 paracrine secretion. In addition, in groups in which fibers were printed farther apart (400 μm), cells produced EVs with a significantly increase cargo. Finally, in vivo experiment results showed an increase in blood vessels density and new bone thickness after 12 weeks of implantation in rat cranial defect, further suggesting the higher efficiency of indirect ECs/MSCs contact in prompting the release of paracrine signals that stimulate the angiogenesis of local tissues, and enhanced subsequent bone regeneration.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): Amin Nozariasbmarz, Mahshid Hosseini, Daryoosh Vashaee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report that microwave radiation can decompose continuous solid-solution materials into their constituent phases – a process that is thermodynamically unfavorable at equilibrium. A detailed analysis of the interaction of the electromagnetic wave with the material showed that a strong ponderomotive force preferentially separates the constituent phases via an enhanced mass transport process amplified particularly near the interfaces. The proof of concept experiments showed that the material, whether it is a solid-solution of two elements, e.g. (Si〈sub〉1-x〈/sub〉Ge〈sub〉x〈/sub〉), or two compounds, e.g. (Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉)〈sub〉1-x〈/sub〉(Sb〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉)〈sub〉x〈/sub〉, decomposes into the constituent phases when radiated by a polarized microwave field. The dissolution happens in the bulk of the material and even below the melting point. The degree of decomposition can be controlled by radiation parameters to produce structures composed of gradient phases of the solid-solution. This offers a novel and facile method for synthesizing gradient composite and complex structures for application in thermoelectricity as well as fabrication of core-shell structures for catalysts and biomedical applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305294-fx1.jpg" width="306" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Dapeng Chen, Yunyun Tang, Jiawei Zhu, Jiaojiao Zhang, Xuejiao Song, Wenjun Wang, Jinjun Shao, Wei Huang, Peng Chen, Xiaochen Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly specific and effective cancer phototherapy remains as a great challenge. Herein, a smart nanoplatform (TENAB NP) sequentially responsive to light, low pH and hypoxia is demonstrated for multi-mode imaging guided synergistic cancer therapy with negligible skin phototoxicity. Upon 808-nm laser irradiation, TENAB NPs can generate hyperthermia to melt the phase change material (PCM-LASA) coat and thereafter release chemo-drug tirapazamine (TPZ). Meanwhile, under acidic pH, photosensitizer ENAB would turn “off” its charge-transfer state, generating prominent 〈sup〉1〈/sup〉O〈sub〉2〈/sub〉 for photodynamic therapy (PDT) and heat for photothermal therapy (PTT), respectively. Accompanied with PDT-induced hypoxia, the released TPZ can be activated into its cytotoxic form for tumor cells killing. Notably, owing to phase change material LASA coat and ENAB's pH sensitivity, TENAB NPs show negligible photosensitization to skin and normal tissues. As the multi-stimuli responsive mechanism, TENAB NPs demonstrate a promising future in cancer photo-chemo theranostics with excellent skin protection.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Anh Tran, Hoang Tran〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microstructure reconstruction problems are usually limited to the representation with finitely many number of phases, e.g. binary and ternary. However, images of microstructure obtained through experimental, for example, using microscope, are often represented as a RGB or grayscale image. Because the phase-based representation is discrete, more rigid, and provides less flexibility in modeling the microstructure, as compared to RGB or grayscale image, there is a loss of information in the conversion. In this paper, a microstructure reconstruction method, which produces images at the fidelity of experimental microscopy, i.e. RGB or grayscale image, is proposed without introducing any physics-based microstructure descriptor. Furthermore, the image texture is preserved and the microstructure image is represented with continuous variables (as in RGB or grayscale images), instead of binary or categorical variables, which results in a high-fidelity image of microstructure reconstruction. The advantage of the proposed method is its quality of reconstruction, which can be applied to any other binary or multiphase 2D microstructure. The proposed method can be thought of as a subsampling approach to expand the microstructure dataset, while preserving its image texture. Moreover, the size of the reconstructed image is more flexible, compared to other machine learning microstructure reconstruction method, where the size must be fixed beforehand. In addition, the proposed method is capable of joining the microstructure images taken at different locations to reconstruct a larger microstructure image. A significant advantage of the proposed method is to remedy the data scarcity problem in materials science, where experimental data is scare and hard to obtain. The proposed method can also be applied to generate statistically equivalent microstructures, which has a strong implication in microstructure-related uncertainty quantification applications. The proposed microstructure reconstruction method is demonstrated with the UltraHigh Carbon Steel micrograph DataBase (UHCSDB).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305178-fx1.jpg" width="322" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): O.I. Gorbatov, A.Yu Stroev, Yu.N. Gornostyrev, P.A. Korzhavyi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The strengthening by coherent, nano-sized particles of metastable phases (pre-precipitates) continues to be the main design principle for new high-performance aluminium alloys. To describe the formation of such pre-precipitates in Al–Cu, Al–Mg, Al–Zn, and Al–Si alloys, we carry out cluster expansions of 〈em〉ab initio〈/em〉 calculated energies for supercell models of the dilute binary Al-rich solid solutions. Effective cluster interactions, including many-body terms and strain-induced contributions due to the lattice relaxations around solute atoms, are thus systematically derived. Monte Carlo and statistical kinetic theory simulations, parameterized with the obtained effective cluster interactions, are then performed to study the early stages of decomposition in the binary Al-based solid solutions. We show that this systematic approach to multi-scale modelling is capable of incorporating the essential physical contributions (usually referred to as atomic size and electronic structure factors) to the free energy, and is therefore able to correctly describe the ordering temperatures, atomic structures, and morphologies of pre-precipitates in the four studied alloy systems.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930521X-fx1.jpg" width="361" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 179〈/p〉 〈p〉Author(s): T. Glechner, R. Hahn, T. Wojcik, D. Holec, S. Kolozsvári, H. Zaid, S. Kodambaka, P.H. Mayrhofer, H. Riedl〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using a combination of density functional theory calculations and nanomechanical testing of sputter-deposited, 110-oriented Ta〈sub〉0.47〈/sub〉C〈sub〉0.34〈/sub〉N〈sub〉0.19〈/sub〉 thin films, we show that non-metal alloying – substituting C with N atoms – in TaC results in a super-hard material with enhanced ductility. Based on the calculated elastic constants, with Pugh and Pettifor criteria for ductile character, we predict that stoichiometric and sub-stoichiometric Ta-C-N alloys are more ductile than Ta-C compounds. From nanoindentation of the as-deposited coating, we measure hardness of 43 ± 1.4 GPa. 〈em〉In situ〈/em〉 scanning electron microscopy (SEM) based micro-compression of cylindrical pillars, prepared via focused ion beam milling of the coating, revealed that Ta-C-N alloys are ductile and undergo plastic deformation with a yield strength of 17 ± 1.4 GPa. The post-compression SEM images of the pillars show {111} 〈〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉01〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mrow〉〈/math〉〉 as the active slip system operating during compression. Additional 〈em〉in situ〈/em〉 SEM based cantilever tests suggest that the Ta-C-N films exhibit superior fracture toughness compared to Ta-C coatings. Our results provide a new perspective on the role of alloying on the mechanical behavior of ultra-high temperature compounds such as transition-metal carbides.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305257-fx1.jpg" width="490" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Zhen Zhang, Ningbo Liao, Hongming Zhou, Wei Xue〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The combination of silicon and carbon layers exhibits superior lithium capacity and rate performance; however, the corresponding lithiation mechanism on the atomic-scale is not clear. In this work, the impact of the carbon layer on the electrochemical performance of silicon-carbon film systems as the lithium anode is investigated by a combination of experiments and first principles calculations. Experimental results show that the sample with the thickest carbon layer presents the smallest first cycle discharge capacities (2814 mAhg〈sup〉−1〈/sup〉); however, this sample also results in the largest capacity retentions after 100 cycles (69%) and the rate capability test (48.4%). Based on first principles calculations, the average length of the Li–Si bond near the silicon-carbon interface is significantly shorter than that in silicon, indicating an irreversible capacity loss. The structure with the largest carbon layer thickness corresponds to enhanced reversible capacity, electronic conductivity and lithium diffusion coefficient, which is consistent with experimental results. Our calculations provide a deeper understanding of irreversible capacity loss and how the primary nanostructure contributes to superior rate performance for silicon-carbon film anode materials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305191-fx1.jpg" width="393" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): J. Narayan, A. Bhaumik, A. Haque〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report pseudo-topotactic growth of single-crystal diamond fibers by nanosecond laser melting of amorphous carbon nanofibers (CNFs) and crystalline multi-wall carbon nanotubes (MWCNTs). A rapid laser melting in a super undercooled state and subsequent quenching convert the tips of CNFs and MWCNTs into phase-pure 〈110〉 nanodiamonds along the growth directions. Subsequent laser pluses melt regions below 〈110〉 nanodiamonds that provide seeds for epitaxial growth. By repeating this process, the length of 〈110〉 nanodiamond fibers can be increased, as each pulse results in ∼50 nm nanodiamond region, depending upon the initial size of CNFs and MWCTs. This conversion process can be carried at ambient temperature and pressure in air. The epitaxial nature of 〈110〉 nanodiamond fibers has been confirmed by systematic electron-back-scatter-diffraction studies along the fiber in high-resolution scanning electron microscopy, and high-resolution TEM imaging and diffraction. The nature of C–C bonding characteristics was studied by high-resolution electron-energy-loss spectroscopy to establish the formation of diamond phase by the characteristic peak at 292 eV for sp〈sup〉3〈/sup〉 bonding (σ〈sup〉∗〈/sup〉), and absence of 284 eV peak for sp〈sup〉2〈/sup〉 (π〈sup〉∗〈/sup〉) graphitic bonding. The characteristic diamond Raman peak at 1332 cm〈sup〉−1〈/sup〉 is found to downshift to 1321 cm〈sup〉−1〈/sup〉 because of phonon confinement in nanodiamonds associated with nanofibers. These nanodiamond structures can be doped with both n- and p-type dopants with concentrations far higher than thermodynamic solubility limit due to solute trapping during quenching from the liquid phase. Thus, these nanodiamond structures provide ideal platform for nanosensing, computing and communication, including efficient field emitting devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541930518X-fx1.jpg" width="237" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Diwakar P. Naragani, Paul A. Shade, Peter Kenesei, Hemant Sharma, Michael D. Sangid〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The small fatigue crack (SFC) growth regime in polycrystalline alloys is complex due to the heterogeneity in the local micromechanical fields, which result in high variability in crack propagation directions and growth rates. In this study, we employ a suite of techniques, based on high-energy synchrotron-based X-ray experiments that allow us to track a nucleated crack, propagating through the bulk of a Ni-based superalloy specimen during cyclic loading. Absorption contrast tomography is used to resolve the intricate 3D crack morphology and spatial position of the crack front. Initial near-field high-energy X-ray diffraction microscopy (HEDM) is used for high-resolution characterization of the grain structure, elucidating grain orientations, shapes, and boundaries. Cyclic loading is periodically interrupted to conduct far-field HEDM to determine the centroid position, average orientation, and average lattice strain tensor for each grain within the volume of interest. Reciprocal space analysis is used to further examine the deformation state of grains that plasticize in the vicinity of the crack. Analysis of the local micromechanical state in the grains ahead of the crack front is used to rationalize the advancing small crack path and growth rate. Specifically, the most active slip system in a grain, determined by the maximum resolved shear stress, aligns with the crack growth direction; and the degree of microplasticity ahead of the crack tip helps to identify directions for potential occurrences of crack arrest or propagation. The findings suggest that both the slip system level stresses and microplasticity events within grains are necessary to get a complete description of the SFC progression. Further, this detailed dataset, produced by a suite of X-ray characterization techniques, can provide the necessary validation, at the appropriate length-scale, for SFC models.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419305075-fx1.jpg" width="270" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Tzu-Cheng Sung, Jia-Sin Yang, Chih-Chen Yeh, Ya-Chu Liu, Yi-Peng Jiang, Ming-Wei Lu, Qing-Dong Ling, S. Suresh Kumar, Yung Chang, Akihiro Umezawa, Hao Chen, Akon Higuchi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Commonly, stem cell culture is based on batch-type culture, which is laborious and expensive. We continuously cultured human pluripotent stem cells (hPSCs) on thermoresponsive dish surfaces, where hPSCs were partially detached on the same thermoresponsive dish by decreasing the temperature of the thermoresponsive dish to be below the lower critical solution temperature for only 30 min. Then, the remaining cells were continuously cultured in fresh culture medium, and the detached stem cells were harvested in the exchanged culture medium. hPSCs were continuously cultured for ten cycles on the thermoresponsive dish surface, which was prepared by coating the surface with poly(N-isopropylacrylamide-co-styrene) and oligovitronectin-grafted poly(acrylic acid-co-styrene) or recombinant vitronectin for hPSC binding sites to maintain hPSC pluripotency. After ten cycles of continuous culture on the thermoresponsive dish surface, the detached cells expressed pluripotency proteins and had the ability to differentiate into cells derived from the three germ layers 〈em〉in vitro〈/em〉 and 〈em〉in vivo〈/em〉. Furthermore, the detached cells differentiated into specific cell lineages, such as cardiomyocytes, with high efficiency.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Nathan Z. Dreger, Zachary K. Zander, Yen-Hao Hsu, Derek Luong, Peiru Chen, Nancy Le, Trenton Parsell, Clause Søndergaard, Misha L. Dunbar, Nathan J. Koewler, Mark A. Suckow, Matthew L. Becker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hernia repair outcomes have improved with more robust material options for surgeons and optimized surgical techniques. However, ventral hernia repairs remain challenging with an inherent risk of post-surgical adhesions in the peritoneal space which can occur regardless of interventional material or its surgical placement. Herein, amino acid-based poly(ester urea)s (PEUs) with varied amount of an allyl ether side chains were modified post polymerization modification with the zwitterionic sulfnate group (3-((3-((3-mercaptopropanoyl)oxy)propyl) dimethylammonio)propane-1-sulfonate) to promote anti-adhesive properties. These alloc-PEUs were processed using roll-to-roll fabrication methods to afford films that were amenable to surface functionalization via a zwitterion-thiol. Functional group availability on the surface was confirmed via fluorescence microscopy, x-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) measurements. Zwitterionic treated PEUs exhibited reduced fibrinogen adsorption 〈em〉in vitro〈/em〉 when compared to unfunctionalized control polymer. A rat intrabdominal cecal abrasion adhesion model was used to assess the extent and tenacity of adhesion formation in the presence of the PEUs. The 10% alloc-PEU zwitterion functionalized material was found to reduce the extent and tenacity of adhesions when compared to adhesion controls and the unfunctionalized PEU controls.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 220〈/p〉 〈p〉Author(s): C.G. Da Silva, M.G.M. Camps, T.M.W.Y. Li, A.B. Chan, F. Ossendorp, L.J. Cruz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To improve the efficacy of cancer vaccines we aimed to modulate the suppressive tumor microenvironment. In this study, the potential of intratumoral immune modulation with poly (I:C), Resiquimod (R848) and CCL20 (MIP3α) was explored. Biodegradable polymeric nanoparticles were used as delivery vehicles for slow and sustained release of these drugs in the tumor area and were combined with specific immunotherapy based on therapeutic peptide vaccination in two aggressive murine carcinoma and lymphoma tumor models. Whereas nanoparticle delivery of poly (I:C) or R848 improved therapeutic efficacy, the combination with MIP3α remarkably potentiated the cancer vaccine antitumor effects. The long-term survival increased to 75–100% and the progression free survival nearly doubled on mice with established large carcinoma tumors. The potent adjuvant effects were associated with lymphoid and myeloid population alterations in the tumor and tumor-draining lymph node. In addition to a significant influx of macrophages into the tumor, the phenotype of the suppressor tumor-associated macrophages shifted towards an acute inflammatory phenotype in the tumor-draining lymph node. Overall, these data show that therapeutic cancer vaccines can be potentiated by the combined nanoparticle mediated co-delivery of poly (I:C), R848 and MIP3α, which indicates that a more favorable milieu for cancer fighting immune cells is created for T cells induced by therapeutic cancer vaccines.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305162-fx1.jpg" width="257" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Weicong Chen, Baoxiang Tian, Jiaqi Liang, Suyue Yu, Yue Zhou, Song Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Endothelial cells (ECs) serve as a barrier between circulating blood and the blood vessel wall. The recruitment and adhesion of monocytes to ECs play a critical role in the initiation of vascular diseases such as atherosclerosis. The functions of ECs are not only regulated by biochemical factors but also hemodynamic forces and matrix stiffness. The deposition of lipids and cholesterol in intima and the aging process may result in the change of stiffness in blood vessels. However, how matrix stiffness influences EC-monocyte interactions is not well understood. Here we investigated the effects of matrix stiffness on the chemotactic migration and adhesion of monocytes to ECs. ECs cultured on either soft (8 kPa) matrix or stiff (40 kPa) matrix had more chemotactic effect on monocytes compared to those on 20 kPa matrix. Moreover, monocyte adhesion exhibited a similar pattern, which was correlated with the expression levels of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). Interestingly, miR-126 and miR-222 showed a reverse expression pattern of VCAM-1 and ICAM-1 respectively. By inhibiting miR-126 and miR-222, the effect of matrix stiffness on monocyte adhesion was abolished, suggesting that the expression of miR-126 (targeting VCAM-1) and miR-222 (targeting ICAM-1) mediated the stiffness effect on the expression of VCAM-1 and ICAM-1. These findings shed lights on how matrix stiffness regulates the interactions of ECs and monocytes and advance our understanding on the pathogenesis of atherosclerosis and aging. This work provides a rational basis for vascular tissue engineering, disease modeling and therapeutic development.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Tiep Tien Nguyen, Tung Thanh Pham, Hanh Thuy Nguyen, Mahesh Raj Nepal, Cao Dai Phung, Zhiwei You, Nikita Katila, Nirmala Tillija Pun, Tae Cheon Jeong, Dong-Young Choi, Pil-Hoon Park, Chul Soon Yong, Jong Oh Kim, Simmyung Yook, Jee-Heon Jeong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Host immune response remains an obstacle in cell-replacement therapy for treating type I diabetes. Long-term systemic immunosuppression results in suboptimal efficacy and adverse reactions. Thus, “cell-particle hybrids” of pancreatic islets and tissue-adhesive, polydopamine-coated, FK506-loaded biodegradable microspheres (PD-FK506-MS) were developed to locally modulate the immune response at the transplantation site. Coating of FK506-MS with PD enabled the rapid formation of stable cell-particle hybrids without significant changes in islet viability and functionality. Extremely low quantities of FK506 (approximately 600 ng per recipient) sustainably released from cell-particle hybrids effectively prolonged survival of xenogeneic islet graft. Interestingly, FK506 exhibited extended bioavailability in the grafts but was undetectable in systemic circulation and other tissues. Moreover, mRNA expression of inflammatory cytokines was significantly inhibited in the PD-FK506-MS-containing grafts but not in lymphoid organs. This study presents a promising platform that facilitates the translation of local immunomodulation towards an effective strategy with improved safety profiles for treating type I diabetes.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 6 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Catherine S. Hansel, Margaret N. Holme, Sahana Gopal, Molly M. Stevens〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The study of sophisticated biomaterials and their cellular targets requires visualization methods with exquisite spatial and temporal resolution to discern cell organelles and molecular events. Monitoring cell-material interactions at high resolution is key for the continued development and optimization of biomaterials, for monitoring cell uptake of cargo, and for understanding the cell response to extracellular cues. This review evaluates the advantages and disadvantages of different forms of electron microscopy and super-resolution microscopy in elucidating how biomaterial surface chemistry and topography can affect intracellular events at the nanoscale.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 220〈/p〉 〈p〉Author(s): Ching Ann Tee, Zheng Yang, Lu Yin, Yingnan Wu, Jongyoon Han, Eng Hin Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The zonal property of articular cartilage endows the tissue with biphasic mechanical properties to withstand shearing force and compressional loading. Current treatments for articular cartilage damage are not able to efficiently restore the zonal organisation and functionality. Size-based sorting of freshly isolated chondrocytes from full thickness (FT) cartilage using a spiral microfluidic device was shown to efficiently separate and enrich zonal chondrocytes. The translational application of this sorting protocol is challenging in the clinical setting due to the limited number of autologous chondrocytes from a patient. It is thus essential to explore the practicability of this sorting protocol on expanded chondrocytes. In this study, we first show that size-sorted zonal chondrocytes expanded on microcarriers in dynamic condition (dMC) were able to support comparable proliferation, while maintaining cell morphology, and the zonal cell size-phenotype relation, in contrast to expansion on a tissue culture plate. We further show that post-expansion size-based sorting can be applied on dMC-expanded FT chondrocytes, generating enriched zonal subpopulations that form phenotypically distinct cartilage constructs in the 3D hydrogel. This study demonstrates a novel scale-up zonal chondrocyte production protocol, incorporating size-based zonal chondrocyte separation and dMC platform, to maintain zonal chondrocytes’ phenotypes better to support zonal repair of articular cartilage.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Chenyu Liu, Kai K. Ewert, Ning Wang, Youli Li, Cyrus R. Safinya, Weihong Qiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Monitoring of nanoparticle-based therapy 〈em〉in vivo〈/em〉 and controlled drug release are urgently needed for the precise treatment of disease. We have synthesized a multifunctional Gd-DTPA-ONB (GDO) lipid by introducing the Gd-DTPA contrast agent moiety into an 〈em〉o〈/em〉-nitro-benzyl ester lipid. By design, liposomes formed from the GDO lipid combine MRI tracking ability and dual-trigger release capabilities with maximum sensitivity (because all lipids bear the cleavable moiety) without reducing the drug encapsulation rate. We first confirmed that both photo-treatment and pH-triggered hydrolysis are able to cleave the GDO lipid and lyse GDO liposomes. We then investigated the efficiency of drug release via the combined release processes for GDO liposomes loaded with doxorubicin (DOX). Relative to neutral pH, the release efficiency in acidic environment increased by 10.4% (at pH = 6.5) and 13.3% (at pH = 4.2). This pH-dependent release response is conducive to distinguishing pathological tissue such as tumors and endolysosomal compartments. The photo-induced release efficiency increases with illumination time as well as with distance of the pH from neutral. Photolysis increased the release efficiency by 13.8% at pH = 4.2, which is remarkable considering the already increased amount of drug release in the acidic environment. In addition, the relaxation time of GDO liposomes was 4.1 times that of clinical Gd-DTPA, with brighter 〈em〉T〈/em〉〈sub〉1〈/sub〉-weighted imaging 〈em〉in vitro〈/em〉 and 〈em〉in vivo〈/em〉. Real-time MRI imaging and 〈em〉in vivo〈/em〉 fluorescence experiments demonstrated tumor targeting and MRI guided release. Furthermore, significant tumor growth inhibition in a treatment experiment using DOX-loaded GDO liposomes clearly demonstrated the benefit of photo-treatment for efficacy: the tumor size in the photo-treatment group was 3.7 times smaller than in the control group. The present study thus highlights the benefit of the design idea of combining efficient imaging/guiding, targeting, and triggerable release functions in one lipid molecule for drug delivery applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305113-fx1.jpg" width="461" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Ruoning Wang, Chenshuang Zhang, Junsong Li, Jinyu Huang, Yaw Opoku-Damoah, Bo Sun, Jianping Zhou, Liuqing Di, Yang Ding〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Natural particles ranging from various cell membranes to nascent proteins are highly optimized for their specific functions 〈em〉in vivo〈/em〉 and possess features that are desired in drug delivery carriers. However, the current endeavor in research on bioparticles is still seeking the appropriate strategy to shield multiple agents and circumvent biological hurdles. These issues have propelled the advancement of lipid-polymer hybrid nanocarriers, which could be employed as drug reservoirs and strive to meet these expectations. We thereby proposed functionalized biopeptide-lipid hybrid particles, which were applied to encapsulating a PLGA polymeric core together with indocyanine green (ICG) and packaged by a lipoprotein-inspired structural shell. To initiate precision tumor-penetrating performance, tLyP-1-fused apolipoprotein A-I-mimicking peptides (D4F) were exploited to impart tumor-homing and tumor-penetrating biological functions. The sub-100 nm drug vehicle possessed a long circulation time with uniform mono-dispersity but was stable enough to navigate freely, penetrate deeply into tumors and deliver its cargoes to the targeted sites. Moreover, ICG-encapsulated penetrable polymeric lipoprotein particles (PPL/ICG) could realize real-time fluorescence/photoacoustic imaging for monitoring 〈em〉in vivo〈/em〉 dynamic distribution. Upon near-infrared (NIR) laser irradiation, PPL/ICG demonstrated a highly efficient phototherapeutic effect to eradicate orthotopic xenografted tumors, resulting in an 88.77% decrease from the initial tumor volume and inhibited tumor metastasis with good biosafety. Therefore, the described bio-strategy opens new avenues for creating polymeric lipoproteins with varied hybrid functionalities, which may be applied to provide a basis and inspiration for improved nanoparticle-based precision theranostic nanoplatforms.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Illustration of penetrating polymeric lipoproteins for deep tumor penetration with targeting recognition of cancer cell via dual-modal imaging and effective phototherapy.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305125-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Justine Creff, Rémi Courson, Thomas Mangeat, Julie Foncy, Sandrine Souleille, C. Thibault, Arnaud Besson, Laurent Malaquin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The small intestine is a complex tissue with a crypt/villus architecture and high tissue polarity. Maintenance of tissue integrity and function is supported by a constant renewal of the epithelium, with proliferative cells located in the crypts and differentiated cells migrating upward to the top of villi. So far, most 〈em〉in vitro〈/em〉 studies have been limited to 2D surfaces or 3D organoid cultures that do not fully recapitulate the tissue 3D architecture, microenvironment and cell compartmentalization found 〈em〉in vivo〈/em〉. Here, we report the development of a 3D model that reproduces more faithfully the architecture of the intestinal epithelium 〈em〉in vitro〈/em〉. We developed a new fabrication process combining a photopolymerizable hydrogel that supports the growth of intestinal cell lines with high-resolution stereolithography 3D printing. This approach offers the possibility to create artificial 3D scaffolds matching the dimensions and architecture of mouse intestinal crypts and villi. We demonstrate that these 3D culture models support the growth and differentiation of Caco-2 cells for 3 weeks. These models may constitute a complementary approach to organoid cultures to study intestinal homeostasis by allowing guided self-organization and controlled differentiation, as well as for 〈em〉in vitro〈/em〉 drug screening and testing.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 221〈/p〉 〈p〉Author(s): Chenxin Chen, Jiahui Chen, Wei Wu, Yongjuan Shi, Liang Jin, Lorenza Petrini, Li Shen, Guangyin Yuan, Wenjiang Ding, Junbo Ge, Elazer R. Edelman, Francesco Migliavacca〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The performance of biodegradable magnesium alloy stents (BMgS) requires special attention to non-uniform residual stress distribution and stress concentration, which can accelerate localized degradation after implantation. We now report on a novel concept in stent shape optimization using a finite element method (FEM) toolkit. A Mg-Nd-Zn-Zr alloy with uniform degradation behavior served as the basis of our BMgS. Comprehensive 〈em〉in vitro〈/em〉 evaluations drove stent optimization, based on observed crimping and balloon inflation performance, measurement of radial strength, and stress condition validation via microarea-XRD. Moreover, a Rapamycin-eluting polymer coating was sprayed on the prototypical BMgS to improve the corrosion resistance and release anti-hyperplasia drugs. 〈em〉In vivo〈/em〉 evaluation of the optimized coated BMgS was conducted in the iliac artery of New Zealand white rabbit with quantitative coronary angiography (QCA), optical coherence tomography (OCT) and micro-CT observation at 1, 3, 5-month follow-ups. Neither thrombus or early restenosis was observed, and the coated BMgS supported the vessel effectively prior to degradation and allowed for arterial healing thereafter.〈/p〉 〈p〉The proposed shape optimization framework based on FEM provides an novel concept in stent design and in-depth understanding of how deformation history affects the biomechanical performance of BMgS. Computational analysis tools can indeed promote the development of biodegradable magnesium stents.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219305137-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 178〈/p〉 〈p〉Author(s): Sam Bakhtiari, Jefferson Zhe Liu, Yinong Liu, Hong Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ti〈sub〉50〈/sub〉Ni〈sub〉50-x〈/sub〉Cu〈sub〉x〈/sub〉 alloys are observed to exhibit multiple martensitic transformations from B2 to an orthorhombic B19 and a monoclinic B19′ phase. In addition, DFT calculations have predicted a B19ʺ phase with a higher monoclinic angle as the thermodynamically stable ground state. This study investigated the effects of Cu content and shear stress on the monoclinic angles, phase stabilities of the various martensites, the minimum energy pathways, and the relative total energies among the phases in this pseudo-equiatomic Ti(Ni〈sub〉50-x〈/sub〉Cu〈sub〉x〈/sub〉) system. A new monoclinic phase (B19〈sub〉M〈/sub〉) with a monoclinic angle lower than that of B19′ was found at above a critical Cu content. This confirms the formation of an intermediate phase in the martensitic transformation sequence of the pseudo-equiatomic Ti(Ni〈sub〉50-x〈/sub〉Cu〈sub〉x〈/sub〉) system but contradicts the crystal structure of the experimentally observed phase. It was found that the monoclinic angles of both B19〈sub〉M〈/sub〉 and B19ʺ decrease with increasing the magnitude of an opposing shear stress to their monoclinic distortion. At above certain critical values of the opposing shear stress, the B19〈sub〉M〈/sub〉 and B19ʺ phases destabilise and transform to lower monoclinic angle phases. In addition, the evidence suggests that the experimentally observed monoclinic B19′ phase is in fact a distorted B19ʺ with a reduced monoclinic angle under an opposing shear stress. With the same argument, the experimentally reported B19 phase is a metastable phase formed under the effect of an opposing shear stress to the monoclinic distortion of B19〈sub〉M〈/sub〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419304987-fx1.jpg" width="254" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 30 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Manon Bonvalet-Rolland, Thomas Philippe, John Ågren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nucleation kinetics in a multicomponent supersaturated solid solution is examined. Attachment rate of atoms to a nucleus of a size close to the critical one is determined combining a thermodynamic extremum principle and the Fokker-Planck equation. Two limiting cases are examined; when bulk diffusion controls the nucleation kinetics and when the process is limited by the interfacial mobility. The mixed regime is also treated. Moreover, the growth law in multicomponent alloys is derived in the general case, when both mechanisms are considered. Additionally, the attachment rate is derived, in the classical framework, from a new macroscopic growth equations and the fundamental role of the interfacial mobility is examined. These new general expressions, for the attachment rates and the growth laws, determined either applying the thermodynamic extremum principle or derived from the classical formalism are found to be consistent.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419301740-fx1.jpg" width="397" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Wei Chen, Shuo Cao, Wenjuan Kou, Jinyu Zhang, Yue Wang, You Zha, Yan Pan, Qingmiao Hu, Qiaoyan Sun, Jun Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ductile-to-brittle transition is commonly observed in metastable 〈em〉β〈/em〉-titanium (Ti) alloys containing 〈em〉ω〈/em〉-precipitates, while the fundamental understanding on 〈em〉ω〈/em〉-embrittlement hitherto remains elusive. In this work, the prototypical Ti-20wt.% Mo metastable 〈em〉β〈/em〉-Ti alloy has been systematically investigated by coupling experiments and first-principles calculation to eliminate this puzzle. It is shown that the structural evolution of 〈em〉ω〈/em〉-phase controls the deformation mechanism transition of twinning-to-slip in Ti-Mo alloy, being the origin of ductile-to-brittle transition of this alloy. The initial trigonal 〈em〉ω〈/em〉-structure continuously collapses to hexagonal 〈em〉ω〈/em〉-structure (structural collapse) whilst Mo-atoms is rejected out concurrently (stoichiometric varieties), both leading to hardening of 〈em〉ω〈/em〉-precipitates. This self-hardening of 〈em〉ω〈/em〉-precipitates was further rationalized in terms of the enhanced propensity for a covalent character of the atomic bond demonstrated by the electronic density of states (DOS) from first-principles calculation. Specifically, the self-hardening behavior of 〈em〉ω〈/em〉-precipitates promotes dislocation slip on isolated planes in lieu of correlative slip on successive planes inside 〈em〉ω1〈/em〉-variant, while dislocations are completely blocked ahead 〈em〉ω2/ω3/ω4-〈/em〉variants. This in turn renders the transition from deformation twinning that contributes to great macro-plasticity to ordinary dislocation slip that contributes to localized deformation bands in the present Ti-Mo alloy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419301776-fx1.jpg" width="377" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Qi Quan, Haoye Meng, Biao Chang, Lei Hong, Rui Li, GuangBo Liu, Xiaoqing Cheng, He Tang, Ping Liu, Yi Sun, Jiang Peng, Qing Zhao, Yu Wang, ShiBi Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Flexible nerve guide conduits (NGCs) are desired in peripheral nerve reconstruction near the joints. Inspired by the engineered structure of the helical tube, we addressed the problems of conventional NGCs often mentioned in clinical feedback. We developed a type of helix-flexible NGC (HF-NGC) and evaluated its mechanical properties as well as its flexibility, and it performed excellently during 〈em〉in vitro〈/em〉 tests. During the 〈em〉in vivo〈/em〉 tests, HF-NGCs and conventional nonflexible NGCs (NF-NGCs) were implanted in a rat sciatic nerve defect model. A short-term investigation showed that Schwan cells (SCs) infiltrated into the helical groove, and most of them belonged to the activated SC type. Compared with NF-NGCs, HF-NGCs had fewer apoptotic SCs. In the long term investigation, HF-NGCs maintained flexibility 〈em〉in vivo〈/em〉 after 3 months. Analyses of the morphometric parameters of nerve fibers and the sciatic nerve function index showed that the HF-NGCs had similar regeneration outcomes to those of traditional NF-NGCs. Therefore, this style of HF-NGC could be used to repair peripheral nerve damage in a cross-joint region with less tension during operation and easy to postoperative rehabilitation. We believe that the HF-NGC is a potentially valuable candidate for clinical use.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 205〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Elizaveta Y. Plotnikov, Zugang Mao, Sung-Il Baik, Mehmet Yildirim, Yongsheng Li, Daniel Cecchetti, Ronald D. Noebe, Georges Martin, David N. Seidman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The temporal evolution of ordered γ’(L1〈sub〉2〈/sub〉)-precipitates precipitating in a disordered γ(f.c.c.) matrix is studied in extensive detail for a Ni-12.5 Al at.% alloy aged at 823 K (550 〈sup〉o〈/sup〉C), for times ranging from 0.08 to 4096 h. Three-dimensional atom-probe tomography (3-D APT) results are compared to monovacancy-mediated lattice-kinetic Monte Carlo (LKMC〈sub〉1〈/sub〉) simulations on a rigid lattice, which include monovacancy-solute binding energies through 4〈sup〉th〈/sup〉 nearest-neighbor distances, for the same mean composition and aging temperature. The temporal evolution of the measured values of the mean radius, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mi〉R〈/mi〉〈mrow〉〈mo〉(〈/mo〉〈mi〉t〈/mi〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉, number density, aluminum supersaturations, and volume fraction of the γ’(L1〈sub〉2〈/sub〉)-precipitates are compared to the predictions of a modified version of the Lifshitz-Slyozov diffusion-limited coarsening model due to Calderon, Voorhees et al. The resulting experimental rate constants are used to calculate the Gibbs interfacial free-energy between the γ(f.c.c.)- and γ’(L1〈sub〉2〈/sub〉)-phases, which enter the model〈em〉,〈/em〉 using data from two thermodynamic databases, and its value is compared to all exiting values. The diffusion coefficient for coarsening is calculated utilizing the same rate-constants and compared to all archival diffusivities, 〈em〉not determined from coarsening experiments, and it is demonstrated to be the inter-diffusivity,〈/em〉 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mi〉D〈/mi〉〈mo〉˜〈/mo〉〈/mover〉〈/mrow〉〈/math〉〈em〉, of Ni and Al.〈/em〉 The monovacancy-mediated LKMC〈sub〉1〈/sub〉 simulation results are in good agreement with our 3-D APT data. The compositional interfacial width, for the {100}-interface, between the γ(f.c.c.)- and γ’(L1〈sub〉2〈/sub〉)-phases, decreases continuously with increasing aging time and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mi〉R〈/mi〉〈mrow〉〈mo〉(〈/mo〉〈mi〉t〈/mi〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉, both for the 3-D APT results and the monovacancy-mediated LKMC〈sub〉1〈/sub〉 simulations, in disagreement with an 〈em〉ansatz〈/em〉 intrinsic to the trans-interface diffusion-controlled coarsening model, which assumes the exact opposite trend for binary alloys.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419301594-fx1.jpg" width="255" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 206〈/p〉 〈p〉Author(s): Can Ni, Jing Zhou, Na Kong, Tianying Bian, Yangheng Zhang, Xiaofeng Huang, Yin Xiao, Wenrong Yang, Fuhua Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The regeneration of lost periodontal apparatus in periodontitis treatment remains a clinical challenge due to the limited regenerative capacity of cementum, periodontal ligament and alveolar bone in periodontitis condition. For periodontal tissue regeneration, it is essential to regulate the inflammatory response and the subsequent differentiation of periodontal cells under the condition due to the infectious nature of the disease. In this study, it was noted that 45 nm gold nanoparticles (AuNPs) could exhibit significant anti-inflammatory effect and improve the periodontal inflammatory microenvironment via regulating inflammatory and regenerative cytokine production and modulating macrophage polarization, subsequently affect the differentiation of human periodontal ligament cells (hPDLCs). With the addition of direct effects of AuNPs on hPDLCs, the periodontal tissue differentiation capacity of hPDLCs in LPS-activated inflammatory macrophage-hPDLCs coculture system was significantly enhanced by the interaction between AuNPs-conditioned macrophage and AuNPs-stimulated hPDLCs. The potential therapeutic application of AuNPs in periodontal tissue regeneration and periodontitis treatment was investigated using both rat fenestration and ligature-induced periodontitis models. It was found that the treatment of 45 AuNPs showed significantly increased newly-formed periodontal attachment, bone and cementum in periodontal defect and less tissue destruction in the progression of periodontitis. This study demonstrated that 45 nm AuNPs could not only directly modulate hPDLCs, but also regulate the early inflammatory response of periodontal tissues via the regulation of macrophage phenotypes, therefore, generate a microenvironment with constraint inflammatory cytokine levels and reparative cytokines such as bone morphogenetic protein-2 (BMP-2), leading to PDLC differentiation, periodontal tissue regeneration and the prevention of periodontitis progression.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Shuang Yang, Xiaoxiu Shi, Xiaoming Li, Jinfeng Wang, Yuanliang Wang, Yanfeng Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Well-aligned collagen fiber scaffolds are considered promising candidates for tendon tissue engineering in terms of their biomimetic chemical composition and topographic structure. Insoluble collagen fibers are more suitable for the preparation of scaffolds than soluble collagens due to their more approximate self-assembly and mechanical properties to native collagen ECMs. In this work, we employed counter-rotating extrusion technology for the first time to fabricate an aligned (CM〈sub〉a〈/sub〉, orientation angle 0°–15°) and a randomly-oriented (CM〈sub〉r〈/sub〉, orientation angle −60° - 60°) collagen membrane from insoluble collagens. CM〈sub〉a〈/sub〉 had a tensile strength comparable with native rat Achilles tendon (18.45 ± 0.91 MPa vs. 22.32 ± 2.48 MPa). Thus, CM〈sub〉a〈/sub〉 represents a scaffold that is biomimetic of native tendon tissues in chemical composition, alignment, and mechanical properties. To verify the feasibility of CMs in tendon tissue engineering, we investigated the 〈em〉in vitro〈/em〉 tenogenic differentiation of rBMSCs on CMs and the 〈em〉in vivo〈/em〉 tendon regeneration using a rat Achilles tendon defect model. Detection of the tendon-related genes and proteins revealed that CM〈sub〉a〈/sub〉 can promote significantly higher tenogenic differentiation of rBMSCs than CM〈sub〉r〈/sub〉, by inducing an elongated cell shape along the fibers. The 〈em〉in-situ〈/em〉 tendon repair study further confirmed that CM〈sub〉a〈/sub〉-BMSCs can produce a comparable healing quality to the autogenous tendon. Overall, our results verify the feasibility of the counter-rotating extrusion technology in fabricating biomimetic collagen scaffolds and provide a promising scaffold for tendon tissue regeneration.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219301930-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Hua Qiu, Pengkai Qi, Jingxia Liu, Ying Yang, Xing Tan, Yu Xiao, Manfred F. Maitz, Nan Huang, Zhilu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Co-immobilization of two or more molecules with different and complementary functions to prevent thrombosis, suppress smooth muscle cell (SMC) proliferation, and support endothelial cell (EC) growth is generally considered to be promising for the re-endothelialization on cardiovascular stents. However, integration of molecules with distinct therapeutic effects does not necessarily result in synergistic physiological functions due to the lack of interactions among them, limiting their practical efficacy. Herein, we apply heparin and nitric oxide (NO), two key molecules of the physiological functions of endothelium, to develop an endothelium-mimetic coating. Such coating is achieved by sequential conjugation of heparin and the NO-generating compound selenocystamine (SeCA) on an amine-bearing film of plasma polymerized allylamine. The resulting surface combines the anti-coagulant (anti-FXa) function provided by the heparin and the anti-platelet activity of the catalytically produced NO. It also endows the stents with the ability to simultaneously up-regulate α-smooth muscle actin (α-SMA) expression and to increase cyclic guanylate monophosphate (cGMP) synthesis of SMC, thereby significantly promoting their contractile phenotype and suppressing their proliferation. Importantly, this endothelium-biomimetic coating creates a favorable microenvironment for EC over SMC. These features impressively improve the antithrombogenicity, re-endothelialization and anti-restenosis of vascular stents 〈em〉in vivo〈/em〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia〈/p〉 〈p〉Author(s): Chenxi Wang, Xiaoming Yang, Zujian Wang, Chao He, Xifa Long〈/p〉 〈div xml:lang="en"〉 〈h5〉ABSTRACT〈/h5〉 〈div〉〈p〉Switching behavior is a general feature in ferroelectrics. The related fatigue effects influenced by defect dipoles in ferroelectrics are still controversial that is focused on the positive and negative effects of oxygen vacancies. Here, we report the polarization switching behavior of acceptor-doped ceramics using the first-order reversal curve (FORC) approach, especially for the abnormal self-rejuvenation effect and the enhanced fatigue endurance in acceptor-doped ceramics. The reversible and irreversible components under electric field in the ceramics were distinguished by the FORC distribution of ideal “hysteron”. The abnormal self-rejuvenation behavior stemmed from dispersive response of hysteron for undoped samples while from the redistribution of defect dipoles for acceptor-doped samples. The self-rejuvenation was induced mainly by the irreversible component. For the fatigue effect, the pinning of domain walls was not the main reason. The re-annealing treatment for a fatigued sample weakened the interactions between the spontaneous polarizations and defect dipoles, but enhanced the dispersion of coercive field. The enhancement of fatigue endurance came from the phase stability of structure in acceptor-doped ceramics, while complex phase evolution existed in undoped ceramic with weak fatigue endurance. Our study shed new light on the interactions between spontaneous polarization and defect dipoles under repetitive AC electric field.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645419301764-fx1.jpg" width="491" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 25 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): H. Autefage, F. Allen, H.M. Tang, C. Kallepitis, E. Gentleman, N. Reznikov, K. Nitiputri, A. Nommeots-Nomm, M.D. O'Donnell, C. Lange, B.M. Seidt, T.B. Kim, A.K. Solanki, F. Tallia, G. Young, P.D. Lee, B.F. Pierce, W. Wagermaier, P. Fratzl, A. Goodship〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The efficient healing of critical-sized bone defects using synthetic biomaterial-based strategies is promising but remains challenging as it requires the development of biomaterials that combine a 3D porous architecture and a robust biological activity. Bioactive glasses (BGs) are attractive candidates as they stimulate a biological response that favors osteogenesis and vascularization, but amorphous 3D porous BGs are difficult to produce because conventional compositions crystallize during processing. Here, we rationally designed a porous, strontium-releasing, bioactive glass-based scaffold (pSrBG) whose composition was tailored to deliver strontium and whose properties were optimized to retain an amorphous phase, induce tissue infiltration and encourage bone formation. The hypothesis was that it would allow the repair of a critical-sized defect in an ovine model with newly-formed bone exhibiting physiological matrix composition and structural architecture. Histological and histomorphometric analyses combined with indentation testing showed pSrBG encouraged near perfect bone-to-material contact and the formation of well-organized lamellar bone. Analysis of bone quality by an unprecedented combination of Raman spectral imaging, small-angle X-ray scattering, X-ray fluorescence and focused ion beam-scanning electron microscopy demonstrated that the repaired tissue was akin to that of normal, healthy bone, and incorporated small amounts of strontium in the newly formed bone mineral. These data show the potential of pSrBG to induce an efficient repair of critical-sized bone defects and establishes the importance of thorough multi-scale characterization in assessing biomaterial outcomes in large animal models.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 25 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Jun Xu, Hui Wang, Ligeng Xu, Yu Chao, Chenya Wang, Xiao Han, Ziliang Dong, Hong Chang, Rui Peng, Yiyun Cheng, Zhuang Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cancer vaccines for prevention and treatment of tumors have attracted tremendous interests as a type of cancer immunotherapy strategy. A major challenge in achieving robust T-cell responses to destruct tumor cells after vaccination is the abilities of antigen cross-presentation for antigen-presenting cells (APCs) such as dendritic cells (DCs). Herein, we demonstrate that a polyamidoamine dendrimer modified with guanidinobenzoic acid (DGBA) could serve as an effective protein carrier to enable delivery of protein antigen, thereby leading to effective antigen cross-presentation by DCs. With ovalbumin (OVA) as the model antigen and unmethylated cytosine-guanine dinucleotides (CpG) as the adjuvant, a unique type of tumor vaccine is formulated. Importantly, such DGBA-OVA-CpG nanovaccine can induce robust antigen-specific cellular immunities and further demonstrates outstanding prophylactic efficacy against B16-OVA melanoma. More significantly, the nanovaccine shows excellent therapeutic effect to treat established B16-OVA melanoma when used in combination with the programmed cell death protein 1 (PD-1) checkpoint-blockade immunotherapy. This study presents the great promises of employing rationally engineered cytosolic protein carriers for the development of tumor vaccines to achieve effective cancer immunotherapy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219301875-fx1.jpg" width="376" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Zhongyu Cai, Yong Wan, Matthew L. Becker, Yun-Ze Long, David Dean〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poly(propylene fumarate) (PPF) is a biodegradable polymer that has been investigated extensively over the last three decades. It has led many scientists to synthesize and fabricate a variety of PPF-based materials for biomedical applications due to its controllable mechanical properties, tunable degradation and biocompatibility. This review provides a comprehensive overview of the progress made in improving PPF synthesis, resin formulation, crosslinking, device fabrication and post polymerization modification. Further, we highlight the influence of these parameters on biodegradation, biocompatibility, and their use in a number of regenerative medicine applications, especially bone tissue engineering. In particular, the use of 3D printing techniques for the fabrication of PPF-based scaffolds is extensively reviewed. The recent invention of a ring-opening polymerization method affords precise control of PPF molecular mass, molecular mass distribution (〈em〉Ɖ〈/em〉〈sub〉M〈/sub〉) and viscosity. Low 〈em〉Ɖ〈/em〉〈sub〉M〈/sub〉 facilitates time-certain resorption of 3D printed structures. Novel post-polymerization and post-printing functionalization methods have accelerated the expansion of biomedical applications that utilize PPF-based materials. Finally, we shed light on evolving uses of PPF-based materials for orthopedics/bone tissue engineering and other biomedical applications, including its use as a hydrogel for bioprinting.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0142961219301887-fx1.jpg" width="250" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials〈/p〉 〈p〉Author(s): Tae-Hyun Kim, Min Sil Kang, Nandin-Erdene Mandakhbayar, Ahmed El-Fiqi, Hae-Won Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Inflammation prevailing conditions delay healing processes of damaged tissues, leading to a functional impairment. Although anti-inflammatory drugs are clinically available, they often cause unwanted side effects thus being considered suboptimal. Here we report drug-free synthetic nanoparticles that target and internalize pro-inflammatory cells and release ions, ultimately demonstrating profound anti-inflammatory functions. Here we introduce folate-functionalized bioactive glass nanoparticle BGN(F) that can target pro-inflammatory cells to endocytose and release ions. The folate-conjugation significantly enhanced the nanoparticle internalization to LPS-induced pro-inflammatory cells. The direct treatment of BGN(F) at proper doses (80–160 μg/mL) substantially down-regulated pro-inflammatory molecules, including TNF-α, IL-6, iNOS and COX-2, at both gene and protein levels. The phosphorylation of intracellular signaling molecules involved in the inflammatory events, such as p38 MAPK, ERK (1/2), SAPK/JANK, IκBα, and NF-κB, were significantly suppressed by the BGN(F) treatment. Furthermore, BGN(F) was potential to switch the macrophage polarization from pro-inflammatory M1 to regenerative M2 phenotype. The released ions, not the physical interactions, of nanoparticles were observed to contribute in major part to the anti-inflammatory actions of BGN(F). The BGN(F), when locally administered to a Notexin-induced myoinjury tissue in mice, significantly down-regulated IL-6 and TNF-α, switched the macrophage phenotype from M1 to M2, and accelerated tissue healing. The current findings that demonstrate profound anti-inflammatory actions of BGN(F) 〈em〉in vitro〈/em〉 and 〈em〉in vivo〈/em〉 support their uses as novel drug-free nanotherapeutic platform for the treatment of inflamed tissues.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volume 206〈/p〉 〈p〉Author(s): Yeong-Jin Choi, Young-Joon Jun, Dong Yeon Kim, Hee-Gyeong Yi, Su-Hun Chae, Junsu Kang, Juyong Lee, Ge Gao, Jeong-Sik Kong, Jinah Jang, Wan Kyun Chung, Jong-Won Rhie, Dong-Woo Cho〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Volumetric muscle loss (VML) is an irrecoverable injury associated with muscle loss greater than 20%. Although hydrogel-based 3D engineered muscles and the decellularized extracellular matrix (dECM) have been considered for VML treatment, they have shown limited efficacy. We established a novel VML treatment with dECM bioink using 3D cell printing technology. Volumetric muscle constructs composed of cell-laden dECM bioinks were generated with a granule-based printing reservoir. The 3D cell printed muscle constructs exhibited high cell viability without generating hypoxia and enhanced 〈em〉de novo〈/em〉 muscle formation in a VML rat model. To improve functional recovery, prevascularized muscle constructs that mimic the hierarchical architecture of vascularized muscles were fabricated through coaxial nozzle printing with muscle and vascular dECM bioinks. Spatially printing tissue-specific dECM bioinks offers organized microenvironmental cues for the differentiation of each cell and improves vascularization, innervation, and functional recovery. Our present results suggest that a 3D cell printing and tissue-derived bioink-based approach could effectively generate biomimetic engineered muscles to improve the treatment of VML injuries.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 165〈/p〉 〈p〉Author(s): Rafael Herschberg, Chu-Chun Fu, Maylise Nastar, Frédéric Soisson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The diffusion of C in Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Cr solid solutions is modelled and compared to experimental data. A set of binding energies and migration barriers for C diffusion in different local chemical environments are first calculated using density functional theory. A pair interaction model is developed in order to reproduce these data and predict the migration barriers in other environments. The diffusion model is then implemented in a kinetic Monte Carlo method to simulate tracer diffusion experiments, using a standard procedure, and internal friction experiments, using a novel method. Simulations of internal friction show a unique Snoek peak in the whole concentration range, between pure iron and pure chromium. The average migration barrier for C diffusion in Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Cr alloys is found to increase progressively with the Cr concentration, with a small rate below 6 %Cr. In Cr-rich alloys, the effective migration barrier for C diffusion is found to be larger in tracer diffusion than in the internal friction simulations. We conclude that the effective migration barrier extracted from tracer diffusion is closely related to trapping effects of C atoms in Fe-rich local environments, whereas the migration barrier associated with internal friction is mainly controlled by the migration barriers of the most probable configurations, as it is clearly shown in the Cr-rich domain.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Tracer diffusion and Internal Friction experiments were simulated via AKMC and compared with the available experimental data. A new model for the Internal Friction was developed and it was also compared with a previous model found in the experimental literature.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645418309017-fx1.jpg" width="426" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 166〈/p〉 〈p〉Author(s): Sinan S. Faouri, Ali Mostaed, Julian S. Dean, Dawei Wang, Derek C. Sinclair, Shiyu Zhang, William G. Whittow, Yiannis Vardaxoglou, Ian M. Reaney〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ceramics-ceramic composites in series (1-〈em〉x〈/em〉)Li〈sub〉2〈/sub〉MoO〈sub〉4〈/sub〉-〈em〉x〈/em〉BaFe〈sub〉12〈/sub〉O〈sub〉19〈/sub〉 (LMO-BF12, 0.00 ≤ 〈em〉x〈/em〉 ≤ 0.15) have been cold sintered at 120 °C and their structure and properties characterized. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that compositions were dual phase and had a dense microstructure. Composites in the 〈em〉x〈/em〉BF12-(1-〈em〉x〈/em〉)LMO (0.0 ≤ 〈em〉x〈/em〉 ≤ 0.15) series resonated at MW frequencies (∼6 GHz) with 5.6≤〈em〉ε〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 ≤ 5.8 and 〈em〉Qf〈/em〉 = 16,000–22,000 GHz, despite the black colour of compositions with 〈em〉x〈/em〉 〉 0. The permeability of the composites was measured in the X band (∼8 GHz) and showed an increase from 0.94 (〈em〉x〈/em〉 = 0.05) to 1.02 (〈em〉x〈/em〉 = 0.15). Finite element modelling revealed that the volume fraction of BF12 dictates the conductivity of the material, with a percolation threshold at 10 vol% BF12 but changes in 〈em〉ε〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 as a function of 〈em〉x〈/em〉 were readily explained using a series mixing model. In summary, these composites are considered suitable for the fabrication of dual mode or enhanced bandwidth microstrip patch antennas.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645418310085-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉