ALBERT

Beschreibung: 〈p〉Publication date: Available online 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Complexity〈/p〉 〈p〉Author(s): Robert J. Kunsch, Erich Novak, Daniel Rudolf〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We compute the integral of a function or the expectation of a random variable with minimal cost and use, for our new algorithm and for upper bounds of the complexity, i.i.d. samples. Under certain assumptions it is possible to select a sample size based on a variance estimation, or – more generally – based on an estimation of a (central absolute) 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll" altimg="si1.gif"〉〈mi〉p〈/mi〉〈/math〉-moment. That way one can guarantee a small absolute error with high probability, the problem is thus called solvable. The expected cost of the method depends on the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll" altimg="si1.gif"〉〈mi〉p〈/mi〉〈/math〉-moment of the random variable, which can be arbitrarily large. In order to prove the optimality of our algorithm we also provide lower bounds. These bounds apply not only to methods based on i.i.d. samples but also to general randomized algorithms. They show that – up to constants – the cost of the algorithm is optimal in terms of accuracy, confidence level, and norm of the particular input random variable. Since the considered classes of random variables or integrands are very large, the worst case cost would be infinite. Nevertheless one can define adaptive stopping rules such that for each input the expected cost is finite. We contrast these positive results with examples of integration problems that are not solvable.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Xing-Wei Xiang, Jin-Xing Xiao, Yu-Fang Zhou, Bin Zheng, Zheng-Shun Wen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The black seabream (〈em〉Sparus macrocephlus〈/em〉) is an economically pivotal aquaculture species cultured in China and Southeast Asian countries. To understand the molecular immune mechanisms underlying the response to 〈em〉Vibrio parahaemolyticus〈/em〉, a comparative gene transcription analysis were performed with utilized fresh livers of 〈em〉V. parahaemolyticus〈/em〉-immunized 〈em〉Sparus macrocephlus〈/em〉 with a control group through RNA-Seq technology. A total of 256663 contigs were obtained after excluded the low-quality sequences and assembly. The average length of contigs collected from this research is 1066.93 bp. Furthermore, blast analysis indicates 30747 contigs were annotated based on homology with matches in the NT, NR, gene, and string databases. A gene ontology analysis was employed to classify 21598 genes according to three major functional categories: molecular function, cellular component, and biological process. A total of 14470 genes were discovered in 303 KEGG pathways. RSEM and EdgeR were introduced to estimate 3841 genes significantly different expressed (False Discovery Rate〈0.001) which includes 4072 up-regulated genes and 3771 down-regulated genes. A significant enrichment analysis of these differentially expressed genes and isogenes were conducted to reveal the major immune-related pathways which refer to the toll-like receptor, complement, coagulation cascades, and chemokine signaling pathways. In addition, 92175 potential simple sequence repeats (SSRs) and 121912 candidate single nucleotide polymorphisms (SNPs) were detected and identified sequencely in the 〈em〉Sparus macrocephlus〈/em〉 liver transcriptome. This research characterized a gene expression pattern for normal and the 〈em〉V. parahaemolyticus〈/em〉 -immunized 〈em〉Sparus macrocephlus〈/em〉 for the first time and not only sheds new light on the molecular mechanisms underlying the host-〈em〉V. parahaemolyticus〈/em〉 interaction but contribute to facilitate future studies on 〈em〉Sparus macrocephlus〈/em〉 gene expression and functional genomics.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Yi-Hong Chen, Jian-Guo He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The shrimp aquaculture industry is plagued by disease. Due to the lack of deep understanding of the relationship between innate immune mechanism and environmental adaptation mechanism, it is difficult to prevent and control the diseases of shrimp. The shrimp innate immune system has received much recent attention, and the functions of the humoral immune response and the cellular immune response have been preliminarily characterized. The role of environmental stress in shrimp disease has also been investigated recently, attempting to clarify the interactions among the innate immune response, the environmental stress response, and disease. Both the innate immune response and the environmental stress response have a complex relationship with shrimp diseases. Although these systems are important safeguards, allowing shrimp to adapt to adverse environments and resist infection, some pathogens, such as white spot syndrome virus, hijack these host systems. As shrimp lack an adaptive immune system, immunization therapy cannot be used to prevent and control shrimp disease. However, shrimp diseases can be controlled using ecological techniques. These techniques, which are based on the innate immune response and the environmental stress response, significantly reduce the impact of shrimp diseases. The object of this review is to summarize the recent research on shrimp environmental adaptation mechanisms, innate immune response mechanisms, and the relationship between these systems. We also suggest some directions for future research.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Yinnan Mu, Shimin Zhou, Ning Ding, Jingqun Ao, Xinhua Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chemokines are a superfamily of structurally related chemotactic cytokines exerting significant roles in regulating cell migration and activation. Currently, five subgroups of fish specific CXC chemokines, named CXCL_F1-CXCL_F5, have been identified in teleost fish. However, understanding of the functions of these fish specific CXC chemokines is still limited. Here, a new member of fish specific CXC chemokines, 〈em〉Lc〈/em〉CXCL_F6, was cloned from large yellow croaker 〈em〉Larimichthys crocea〈/em〉. Its open reading frame (ORF) is 369 nucleotides long, encoding a peptide of 122 amino acids (aa). The deduced 〈em〉Lc〈/em〉CXCL_F6 protein contains a 19-aa signal peptide and a 103-aa mature polypeptide, which has four conserved cysteine residues (C〈sup〉28〈/sup〉, C〈sup〉30〈/sup〉, C〈sup〉56〈/sup〉, and C〈sup〉72〈/sup〉), as found in other known CXC chemokines. Phylogenetic analysis showed 〈em〉Lc〈/em〉CXCL_F6 formed a separate clade with sequences from other fish species, tentatively named CXCL_F6, distinct from the clades formed by fish CXCL_F1-5 and mammalian CXC chemokines. The 〈em〉Lc〈/em〉CXCL_F6 transcripts were constitutively expressed in all examined tissues and significantly up-regulated in the spleen and head kidney tissues by poly (I:C) and 〈em〉Vibrio alginolyticus〈/em〉. Its transcripts were also detected in primary head kidney leukocytes (HKLs), peripheral blood leucocytes (PBLs), and large yellow croaker head kidney (LYCK) cell line, and significantly up-regulated by poly(I:C), lipopolysaccharide (LPS), and peptidoglycan (PGN) in HKLs. Recombinant 〈em〉Lc〈/em〉CXCL_F6 protein (r〈em〉Lc〈/em〉CXCL_F6) could not only chemotactically attract monocytes/macrophages and lymphocytes from PBLs, but also enhance NO release and expression of proinflammatory cytokines (TNF-α, IL-1β, and CXCL8) in monocytes/macrophages. These results indicate that 〈em〉Lc〈/em〉CXCL_F6 plays a role in mediating the inflammatory response.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Computers in Industry, Volume 104〈/p〉 〈p〉Author(s): Jacques Bahi, Wiem Elghazel, Christophe Guyeux, Mourad Hakem, Kamal Medjaher, Noureddine Zerhouni〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Monitoring activities in industry may require the use of wireless sensor networks, for instance due to difficult access or hostile environment. But it is well known that this type of networks has various limitations like the amount of disposable energy. Indeed, once a sensor node exhausts its resources, it will be dropped from the network, stopping so to forward information about maybe relevant features towards the sink. This will result in broken links and data loss which impacts the diagnostic accuracy at the sink level. It is therefore important to keep the network's monitoring service as long as possible by preserving the energy held by the nodes. As packet transfer consumes the highest amount of energy comparing to other activities in the network, various topologies are usually implemented in wireless sensor networks to increase the network lifetime. In this paper, we emphasize that it is more difficult to perform a good diagnostic when data are gathered by a wireless sensor network instead of a wired one, due to broken links and data loss on the one hand, and deployed network topologies on the other hand. Three strategies are considered to reduce packet transfers: (1) sensor nodes send directly their data to the sink, (2) nodes are divided by clusters, and the cluster heads send the average of their clusters directly to the sink, and (3) averaged data are sent from cluster heads to cluster heads in a hop-by-hop mode, leading to an avalanche of averages. Their impact on the diagnostic accuracy is then evaluated. We show that the use of random forests is relevant for diagnostics when data are aggregated through the network and when sensors stop to transmit their values when their batteries are emptied. This relevance is discussed qualitatively and evaluated numerically by comparing the random forests performance to state-of-the-art PHM approaches, namely: basic bagging of decision trees, support vector machine, multinomial naive Bayes, AdaBoost, and Gradient Boosting. Finally, a way to couple the two best methods, namely the random forests and the gradient boosting, is proposed by finding the best hyperparameters of the former by using the latter.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Scripta Materialia, Volume 162〈/p〉 〈p〉Author(s): Cong-Yu Zhang, Hao Chen, Jia-Ning Zhu, Wen-Bo Liu, Geng Liu, Chi Zhang, Zhi-Gang Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The steady-state assumption in the classical solute drag (SD) models is not always valid in treating the complex interaction between alloying elements and migrating interfaces (grain/phase boundaries) in steels. In this study, a general treatment based on phase-field theory is proposed to capture the SD effects of alloying elements without the steady state assumption, while it reduces to the SD models under steady-state assumption. This new treatment can predict the interaction between migrating interfaces and alloying elements with strong segregation tendencies, which cannot be captured by the classical SD models.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359646218306535-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 164〈/p〉 〈p〉Author(s): Bernard Gaskey, Ian McCue, Alyssa Chuang, Jonah Erlebacher〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A major challenge in the synthesis of high surface area metals via subtractive processes such as dealloying is maintaining the mechanical integrity of the resulting porous materials. This problem is especially apparent in liquid metal dealloying, in which high-temperature selective dissolution in a molten metal bath leads to bicontinuous porosity formation. In liquid metal dealloying of polycrystalline alloys, grain boundary separation leads to the detachment of individual grains. In this work, we show that addition of small amounts of silicon to Nb〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Ti or Ta〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Ti parent alloys leads to the generation of self-assembled arrays of intermetallic (niobium silicide or tantalum silicide) plates that are structurally merged with the usual bicontinuous porosity seen in dealloying. These silicide plates pass through grain boundaries and hold the niobium or tantalum network intact without strongly affecting the microstructural evolution during dealloying. Our approach yields a mechanically robust porous metal-intermetallic composite, which can be further processed to form tertiary materials via re-impregnation by a new third phase. The materials design strategy introduced here can be generalized to serve as a platform to form dense multiphase nanocomposites.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S135964541830867X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the Mechanics and Physics of Solids, Volume 122〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Marine Policy, Volume 99〈/p〉 〈p〉Author(s): Pablo Quero García, Javier García Sanabria, Juan Adolfo Chica Ruiz〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In recent years the European Union has firmly committed itself to energy from oceans as a means of decarbonising the European energy system. Despite a favourable political landscape, the development of offshore renewables still faces economic and technological barriers, which are coupled with the inherent difficulties of an increasingly industrialised marine environment, such as complex evolving regulation, lack of knowledge regarding the possible environmental impact of such an activity, as well as spatial conflicts with other traditional and emerging uses. Most of the coastal Member States have adopted Maritime Spatial Planning (MSP) as a fundamental tool for integrated and sustainable management of human activities in the marine environment. MSP is capable of definitively driving the use of offshore renewable facilities. Its proper application supports decision making, simplifies and accelerates the process of obtaining permits, improves compatibility of uses, integrates stakeholders in planning, prevents environmental deterioration of sensitive areas, enhances the availability of information and promotes cross-border co-operation. This paper aims to evaluate the influence of maritime spatial planning processes on the advance of blue energy within the framework of the European Union. The results show positive relationships between MSP and the development of offshore renewable energy in countries such as Germany, the Netherlands and the United Kingdom.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0308597X1830304X-fx1.jpg" width="477" alt="fx1" title="fx1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Marine Policy, Volume 99〈/p〉 〈p〉Author(s): Bong-Tae Kim, Christopher L. Brown, Do-Hoon Kim〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We assess the vulnerability to climate change of Korean aquaculture based on predicted changes in seawater temperature and salinity in adjacent sea areas of the Korean Peninsula according to representative concentration pathways (RCP) scenarios. Unlike previous studies that have been conducted mostly on a national scale, we classify 14 farming species in major production regions of the Republic of Korea, and assess their vulnerability for each region, using the indicator-based method and the Intergovernmental Panel on Climate Change's definition of vulnerability in order to overcome limitations in developing specific adaptation strategies within a country. First, for each exposure, sensitivity, and adaptive capacity, specific and proper indicators are selected. Subsequently, these indicators are estimated and weighted to analyze vulnerability to climate change. The results show that the absolute level of vulnerability is high in a long-term period of RCP8.5 in which exposure becomes severe, whereas the relative vulnerability is similar among farming species and regions. Specifically, vulnerability is at the highest level in seaweed, such as laver and sea mustard, while fish, shrimp, and abalone are relatively less vulnerable to climate change.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): X.Y. Wang, S.L. Zhang, S.D. Feng, L. Qi, R.P. Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structures of the Ti〈sub〉75〈/sub〉Al〈sub〉25〈/sub〉 alloy during rapid-quenching with and without external pressure are investigated by using molecular dynamic techniques. The amorphous phase can be obtained at the cooling rate 10.0 K/ps without pressure. The alloy is composed of crystal and amorphous phase at the cooling rate 0.1 and 1.0 K/ps without pressure, but the pure amorphous phase can be formed when the pressure exceeds the critical value. The critical pressure is about 20 and 30 GPa when the cooling rate is 0.1 and 1.0 K/ps, respectively. H-A indices analysis indicates that high pressure favors the formation of the ideal icosahedral structures in the amorphous Ti〈sub〉75〈/sub〉Al〈sub〉25〈/sub〉 alloy, and the content of 1551 bond-type can reach near to 50% when the pressure is 30 GPa. The amorphous state can be maintained if the external pressure is removed from the alloy step-by-step. The content of 1551 bond-type decreases with the deceasing of the pressure, but the 1541 and 1431 bond-types increase in this process.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Yunli Zhang, Song Hu, Yingli Liu, Zhengjuan Wang, Wei Ying, Guohong Zhou, Shiwei Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of red-emitting Mn〈sup〉4+〈/sup〉 doped Lu〈sub〉3〈/sub〉Al〈sub〉5〈/sub〉O〈sub〉12〈/sub〉 (LuAG) ceramic phosphors were successfully prepared by a simple solid-state reaction method in a high-temperature muffle. MgO was co-doped as sintering aids and Mg〈sup〉2+〈/sup〉 ions helped to realize the charge balance. The relations between the luminescence properties, crystal structures and the microstructures were well established. Results indicated that MgO promoted the densification of the ceramics as the specimens’ relative densities were up to 99%. Moreover, the substitution of Al〈sup〉3+〈/sup〉 with Mg〈sup〉2+〈/sup〉 have changed crystal structures and further affected the luminescent properties. Overall, the obtained ceramic phosphors showed strong red-light emission under excitation of ultraviolet and blue light. By optimizing the Mg〈sup〉2+〈/sup〉 and Mn〈sup〉4+〈/sup〉 concentration, a quantum efficiency (QE) as high as 47.8% can be achieved under the excitation of 460 nm light, indicating that the LuAG: Mn〈sup〉4+〈/sup〉 ceramic phosphors are promising candidates for WLEDs applications.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): GuoShuai Qin, Xin Zhang, MingHao Zhao, Gang Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, three-point bending testing of an edge-cracked specimen and finite element analysis were used to determine the fracture toughness of GaN piezoelectric semiconductive ceramics, and the effect of an applied electric current on the fracture properties of the GaN ceramics was investigated. The results indicated that an electric current has a significant effect on the fracture behavior of piezoelectric semiconductive ceramics. Specifically, the application of a relatively low electric current density (1.67 × 10〈sup〉4〈/sup〉 A m〈sup〉−2〈/sup〉) increased the fracture toughness by 36.8%, while further increases in electric current density reduced the fracture toughness. In addition, the electric current can lead to the ductile fracture of brittle GaN ceramics. Finally, the mechanisms behind these results were systematically analyzed. These findings are useful for designing more reliable GaN electromechanical devices.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Daniel Marinha, Manuel Belmonte〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Composites of 8 mol% Yttria-stabilized Zirconia (YSZ) containing 0, 7, 10 and 14 vol.% of graphene nano-platelets (GNP) were fully densified by Spark Plasma Sintering. The effect of GNP on the electrical performance of the composites was analyzed by impedance spectroscopy as a function of temperature (150–800 °C) and oxygen partial pressure (0.21–10〈sup〉−20〈/sup〉 atm). Results show that below GNP percolation threshold (7.1 vol.%), the electrical behavior is dominated by the matrix oxygen-ion conductivity. Above the threshold, the conductivity is predominantly electronic provided by the GNP network. The total conductivity of composites was used as an indicator of GNP stability in different atmospheres. YSZ/GNP composites remain stable in inert conditions up to 600 °C, and in reducing conditions up to 800 °C, making them good alternatives to perovskite-based materials used for electrochemical applications.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): T. Kolodiazhnyi, T. Charoonsuk, M. Spreitzer, N. Vittayakorn〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report on magnetism, charge transport, dielectric properties and specific heat of Ce〈sub〉1−〈em〉x〈/em〉〈/sub〉Sb〈sub〉〈em〉x〈/em〉〈/sub〉O〈sub〉2〈/sub〉 ceramics sintered at 1650 〈sup〉∘〈/sup〉C with a final antimony content of 0 ≤ 〈em〉x〈/em〉 ≤ 0.0017. In contrast to other donor dopants, such as Nb, Ta, U and W, charge compensation of antimony in Ce〈sub〉1−〈em〉x〈/em〉〈/sub〉Sb〈sub〉〈em〉x〈/em〉〈/sub〉O〈sub〉2〈/sub〉 does not involve the formation of the Ce〈sup〉3+〈/sup〉 ions as revealed by the magnetic susceptibility data. Therefore, we conclude that antimony is mainly present as Sb〈sup〉3+〈/sup〉 ion and acts as an acceptor dopant in Ce〈sub〉1−〈em〉x〈/em〉〈/sub〉Sb〈sub〉〈em〉x〈/em〉〈/sub〉O〈sub〉2〈/sub〉. This conclusion is also supported by a very low electrical conductivity of the Sb-doped ceria that shows an activation energy 〈em〉E〈/em〉〈sub〉〈em〉σ〈/em〉〈/sub〉 ∼ 0.97 eV. This activation energy is close to that observed in oxygen conducting acceptor-doped ceria and is significantly higher than the typical 〈em〉E〈/em〉〈sub〉〈em〉σ〈/em〉〈/sub〉 ∼ 0.1–0.3 eV values reported for 〈em〉n〈/em〉-type CeO〈sub〉2〈/sub〉. Below 10 K, both an anomaly in the dielectric loss and a small specific heat surplus in Sb-doped ceria indicate a low-energy dipolar relaxation probably associated with a local dynamics of the off-centered Sb〈sup〉3+〈/sup〉 point defects.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Fei Zhang, Jérôme Chevalier, Christian Olagnon, Shuigen Huang, Wout Veulemans, Kim Vanmeensel, Jef Vleugels〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Slow crack growth (SCG) behavior of four zirconia-based composites reinforced with 40 vol% WC, TiC, NbC or TiCN were studied by means of double-torsion testing. Compared to monolithic zirconia, the composites had a higher resistance to fast fracture, i.e., higher fracture toughness. The extent of toughening depended on the reinforcement type, shifting the V-K〈sub〉I〈/sub〉 (crack velocity versus stress intensity factor) curve parallel to higher K〈sub〉I〈/sub〉 values. More importantly, these composites were less sensitive to SCG. Identical V-K〈sub〉I〈/sub〉/K〈sub〉IC〈/sub〉 curves with steeper slopes compared to monolithic zirconia were observed for the investigated composites, independent on the reinforcement type. No rising R-curve was measured, at least in the crack-size domain investigated by SCG. Therefore, the higher SCG resistance of the composites was due to the intrinsic stress-assisted corrosion resistance of the covalent non-oxide secondary phase.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Christian Thieme, Michael Kracker, Christian Patzig, Katrin Thieme, Christian Rüssel, Thomas Höche〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glasses with the base composition 8 BaO·8 SrO·34 ZnO·50 SiO〈sub〉2〈/sub〉 were studied with respect to the crystallization of a phase with the composition Ba〈sub〉0.5〈/sub〉Sr〈sub〉0.5〈/sub〉Zn〈sub〉2〈/sub〉Si〈sub〉2〈/sub〉O〈sub〉7〈/sub〉. Some glasses were doped with gold and/or antimony oxide. All glasses exhibited solely surface crystallization. If the glasses contained both antimony and gold, they showed red coloration after different heat treatments and the crystal growth velocities were enhanced, depending on the chosen temperature, by around a factor of 30. Crystals were proven to be oriented statistically, while in all other glasses of the system under consideration, i.e., in those which did not contain both gold and antimony, an orientation of the crystals with their c-axes perpendicular to the surface was obtained. This effect is explained by a continuous nucleation in front of the growing crystals.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Dries Van Laethem, Johan Deconinck, Annick Hubin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ionic conductivity of acceptor doped ceria is strongly influenced by grain boundaries and interfaces. Most experiments show a decrease in ionic conductivity and an increase in electronic conductivity in these regions. Classical models explain this observation by the formation of space charge layers that are depleted of mobile ionic charge carriers and enriched in small polarons. However, some experiments demonstrate an increase in ionic conductivity and recent models show that the space charge layers can also be enriched in mobile ionic species. Because of these contradictions, it is still not clear whether nanocrystalline or thin film ceria can offer superior ionic conductivity or not. To aid this debate, we calculate the ionic conductivity of yttrium doped ceria in regions of net charge density using kinetic Monte Carlo simulations. Through an appropriate choice of the charge densities, these calculations allow to demarcate the possible conductivity gains from space charge layers.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Nikolas Grünwald, Yoo Jung Sohn, Xiaoyan Yin, Norbert H. Menzler, Olivier Guillon, Robert Vaßen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dense protective layers are needed to reduce chromium-related degradation in SOFC stacks. In particular, atmospheric plasma sprayed (APS) Mn〈sub〉1.0〈/sub〉Co〈sub〉1.9〈/sub〉Fe〈sub〉0.1〈/sub〉O〈sub〉4〈/sub〉 (MCF) coatings demonstrated low degradation rates in stack tests. We show that short-term annealing in air induces crack healing within these coatings. Parallel to this effect, a phase transformation is observed originating from oxidation that proceeds by solid state-diffusion. The present contribution reveals the basic mechanisms of the microstructural and phase changes of coatings in long-term annealing tests of up to 10,000 h at 700 °C. The layer develops differently at the air-facing surface and in the bulk. Due to cation deficiency, oxidation is dominated by cation outward diffusion, leading to a Co-enriched surface layer. The bulk displays a fine distribution of the initial (rock salt) and the final (spinel) phases. Understanding the mechanisms leading to these irreversible changes enables predictions to be made concerning durable protectivecoatings in SOFCs.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Sana Algharaibeh, Anthony J. Ireland, Bo Su〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly aligned lamellar ceramic scaffolds were produced using a bi-directional freeze casting technique. A specially designed, sloped copper mould was covered with a polymer to modulate the temperature field. Effects of different processing parameters (cooling rate, mould slope angle, ceramic solid loading and binder concentration) on lamellar orientation were systematically studied. The results showed that freezing under a dual temperature gradient produced highly aligned ceramic scaffolds. Increasing both the cooling rate and the mould slope angle increased the size of the ordered ceramic region. Using different alumina solid loadings in the initial suspension had little effect on the aligned lamellar structure. Increasing the binder concentration affected ice crystal growth in a highly aligned direction. Therefore, freeze casting using a dual temperature gradient can be used to fabricate highly aligned porous materials.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Jörg Exner, Michael Schubert, Dominik Hanft, Jaroslaw Kita, Ralf Moos〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Aerosol deposition features the formation of dense and well adhering ceramic films directly at room temperature, without the need of any heat treatment during or after the deposition. While these claims are true for a 〈em〉suitable〈/em〉 ceramic powder, the success of the film deposition is highly dependent on the 〈em〉right〈/em〉 choice of the powder. Beside the commonly stated particle size that should be in the sub-micrometer to micrometer range, other influencing powder parameters exist, some of which have not yet been fully identified.〈/p〉 〈p〉In this work, ceria nanopowders were thermally pretreated and the quality of subsequent sprayed films was observed. A minimum crystallite size in the powder was determined in order to enable the underlying deposition mechanism. Furthermore, the conversion of kinetic particle energy to the formation of surface energy during impact was estimated. A first universal behavior is found leading to a recommendation for a suitable AD powder preparation.〈/p〉 〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Zhijian Sun, Lei Liu, Yuxiao Lu, Guangyue Shi, Jiajun Li, Lei Ma, Jie Zhao, Hongli An〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉NASION-type Li〈sub〉1.5〈/sub〉Al〈sub〉0.5〈/sub〉Ge〈sub〉1.5〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉3〈/sub〉(LAGP) is prepared by a novel sol-gel method using low cost inorganic germanium (GeO〈sub〉2〈/sub〉) as the precursor. The composition and phase transformation during the heating of the LAGP precursors are analyzed using thermogravimetric-differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD). The structures and morphologies of the LAGP are characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the LAGP annealed at 900 ℃ is partially crystallized and consists of a large number of nanoscale grains surrounded by amorphous regions. The LAGP particles present an irregular morphology with a large size distribution over a range of 0.2–1 μm. In addition, ionic conductivities of the prepared LAGP first increase and then decrease with an increase in the sintering temperature and time. A high ionic conductivity (4.18 × 10〈sup〉−4〈/sup〉Scm〈sup〉-1〈/sup〉) with an activation energy of 0.30 eV are obtained for the LAGP sample sintered at 900 °C for 8 h.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Anne-Isabelle Bidegaray, Andrea Ceglia, Maria Rita Cicconi, Van-Thai Pham, Amandine Crabbé, El Amine Mernissi Cherigui, Karin Nys, Herman Terryn, Daniel R. Neuville, Stéphane Godet〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The analysis of iron, manganese and antimony in silicate glass is of great interest in chemistry, materials science, earth sciences and archaeological sciences. Yet, conclusions from different fields appear to be contradictory and many questions about redox reactions in glass remain. The purpose of this study is thus to discuss whether and how these multivalent elements interact in glass. Soda-lime silicate melts containing iron along with manganese and/or antimony have been analysed at different high temperatures under argon atmosphere. Using 〈em〉in-situ〈/em〉 XANES at the Fe K-edge, redox thermodynamics, kinetics and diffusivities have been assessed for the different compositions. The data obtained show that antimony is more efficient at oxidising iron compared to manganese at all temperatures. The oxidising power trend would thus be Sb 〉 Sb + Mn 〉 Mn. Furthermore, hypotheses on the formation of Fe-Mn complexes are also reported in glasses with stoichiometric proportions of iron and manganese. Based on the determination of redox diffusivities, it appears that presence of other multivalent elements does not significantly affect the iron redox mechanisms and that diffusivity is essentially controlled by the mobility of calcium.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Wentao Zhang, Feng He, Junlin Xie, Xiaoqing Liu, De Fang, Hu Yang, Zhihong Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glass ceramics from modified molten blast furnace (BF) slag were prepared. The crystallization behavior of the modified BF slag was characterized using differential thermal analysis (DTA), X-ray diffraction (XRD), and field emission scanning electron microscope (FESEM). The crystallization kinetics results indicated that the crystallization activation energy initially decreased and subsequently increased with increasing CaO/SiO〈sub〉2〈/sub〉. The crystallization temperature and the crystallization index (n) decreased from 916 to 867 °C, and 5.66–1.13, respectively. The crystallization mechanism transformed from bulk crystallization to surface crystallization. By XRD analyzing, Melilite was developed as the main crystal phase, and the transformation of crystal from akermanite to gehlenite was observed. The rapid surface crystallization was beneficial for maintaining the shape of glass ceramics. The complex replacement in melilite crystals resulted in the micro cracks in glass ceramics, therefore led to the decrease of flexural strength of glass ceramics〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): B.C. Jamalaiah〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different amounts of GeO〈sub〉2〈/sub〉 activated tellurite tungstate glasses were prepared by melt quenching technique. Thermal stability and glass forming ability were studied using differential scanning calorimetry. The chemical composition, homogeneity and amorphous nature of studied glasses were investigated. The phonon energy was estimated to be 721.34 cm〈sup〉−1〈/sup〉. Experimentally determined refractive indices were compared with those determined from optical band gap (E〈sub〉g〈/sub〉) and optical electronegativity (Δ〈em〉χ〈/em〉〈sup〉∗〈/sup〉). The dielectric constant (K) and electronic polarizability (α) were determined using refractive index value. The presence of disorder was estimated in terms of Urbach energy (E〈sub〉U〈/sub〉). The average electronegativity (〈em〉χ〈/em〉〈sub〉〈em〉ave〈/em〉〈/sub〉), oxide ion polarizability (〈em〉α〈/em〉〈sub〉〈em〉O〈/em〉〈/sub〉〈sup〉2−〈/sup〉) and covalent character (C〈sub〉cov〈/sub〉) were determined. The content of GeO〈sub〉2〈/sub〉 was optimized to be 10.0 mol% to design a novel host material for solid state lasers and fiber devices.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Chunhe Jiang, Kejiang Li, Jianliang Zhang, Qinghua Qin, Zhengjian Liu, Minmin Sun, Ziming Wang, Wang Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SiO〈sub〉2〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-CaO-MgO is the most significant slag system in the blast furnace ironmaking process and it is very important to investigate the microstructure and viscosity of the system. In this paper, molecular dynamics simulations were carried out to explore the effects of MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio on structure and properties of the system. Based on the self-diffusion coefficients, the viscosities were calculated by Einstein-Stokes equation and compared with the experimental value and the Factsage value. The results showed that with the increase of MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio, the stability of [SiO〈sub〉4〈/sub〉]〈sup〉4−〈/sup〉 and [AlO〈sub〉4〈/sub〉]〈sup〉5−〈/sup〉 tetrahedron became weaken and the relative proportions of bridge and non-bridge oxygen showed a decrease. And due to the increase of MgO, more Mg〈sup〉2+〈/sup〉 ions are used as network modifiers to reduce the degree of polymerization of the system, resulting in a decrease in the viscosity, which is consistent with experimental results. Finally, based on the present study, in the case of increasing Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content of blast furnace slag, the fluidity of slag could be adjusted by controlling MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio, thereby providing a basis for stable operation of blast furnace ironmaking.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): A.I. Popov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The definition of glassy state presented by the authors of the article “The glassy state of matter: Its definition and ultimate fate” E. Zanotto and J. Mauro is considered. The importance of the contribution to the glassy state problem made in the article is emphasized. At the same time consideration of the glassy state as unstable state of matter causes definite objections. It is more correctly to consider the glassy state as metastable state of matter.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): M.G. Syamala Rao, M.A. Pacheco-Zuñiga, L.A. Garcia-Cerda, G. Gutiérrez-Heredia, J.A. Torres Ochoa, M.A. Quevedo López, R. Ramírez-Bon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we developed a novel inorganic-organic hybrid gate dielectric by combining zirconium and hafnium components to form zirconium hafnium oxide strongly linked with polymethyl methacrylate (ZrHfO〈sub〉2〈/sub〉-PMMA) and deposited at low temperature (200 °C) by sol-gel method. The obtained 108 nm thick, high-quality hybrid gate dielectric showed an exceptionally low surface roughness (0.9-nm), a low leakage current density (7.7 × 10〈sup〉−6〈/sup〉 A/cm〈sup〉2〈/sup〉) and reasonable dielectric properties such as gate capacitance along with dielectric constant (77 nF/cm〈sup〉2〈/sup〉 & 9.4 @1 kHz) respectively. To examine the ZrHfO〈sub〉2〈/sub〉-PMMA hybrid dielectric electrical properties we constructed thin-film transistors (TFTs) with room temperature r.f sputtered n-type metal oxide semiconductors, a-IGZO and ZnO, as active channels. The bottom gate fabricated a-IGZO TFTs driving at as low as below 6 V, with extracted field effect mobility of 2.45 cm〈sup〉2〈/sup〉/V. s, a low threshold voltage of 1.2 V with large ON/OFF current ratio 10〈sup〉7〈/sup〉 respectively. On the other hand, for comparison we employed ZnO TFTs by applying same hybrid dielectric system, the obtained parameters of bottom gate ZnO TFTs were good field effect saturation mobility of 12.8 cm〈sup〉2〈/sup〉/V. s, threshold voltage of 1.8 V and ON/OFF current ratio of 10〈sup〉3〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Weidi Zhu, Mark Lockhart, Bruce Aitken, Sabyasachi Sen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The viscoelastic properties of supercooled As〈sub〉x〈/sub〉Se〈sub〉100-x〈/sub〉 (0 ≤ x ≤ 30) and As〈sub〉x〈/sub〉Se〈sub〉100-x-y〈/sub〉I〈sub〉y〈/sub〉 (x = 20, 30 and y = 10, 20) liquids are studied using oscillatory parallel plate rheometry. In addition to the α-relaxation process, the shear relaxation of liquids with selenium chains longer than ~ 3 atoms is also characterized by a low-frequency polymeric mode. The temporal decoupling of this low-frequency soft/floppy relaxation mode from that of the α-relaxation mode is a unique function of the average selenium chain length. The floppy mode abruptly vanishes for liquids with average chain lengths shorter than ~ 3 Se atoms, thus implying a dynamical rigidity transition. When taken together, these results indicate that, contrary to the conventional wisdom, the pertinent structural variable associated with such transition in the viscoelastic behavior is not the average coordination number but instead the intermediate-range structural elements such as the average selenium chain length.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): M.S.A. Mohd Saidi, S.K. Ghoshal, K. Hamzah, R. Arifin, M.F. Omar, M.K. Roslan, E.S. Sazali〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the influence of silver (Ag) and titania (TiO〈sub〉2〈/sub〉) nanoparticles (ATNPs) co-embedment on the photoluminescence (PL) properties of dysprosium ions (Dy〈sup〉3+〈/sup〉) doped zinc-magnesium tellurite glass system prepared using conventional melt quenching method. Both up- and down- converted PL spectra of glasses revealed three emission bands located at 482 (blue: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉15/2〈/sub〉), 574 (yellow: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉13/2〈/sub〉) and 664 nm (weak red: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉11/2〈/sub〉), where the band intensities were enhanced with the inclusion of ATNPs. Glasses with 0.2 mol% of ANPs and up to 0.3 mol% of TNPs disclosed highest PL intensity enhancement, which was majorly attributed to the ATNPs mediated localized surface plasmon resonance (LSPR) and large field enhancement (called hot spot) effects in the proximity of Dy〈sup〉3+〈/sup〉 ions. Absorption spectra of glasses displayed two plasmon bands characteristics of each type of nanoparticle. It was inferred that the superposition of localized SP modes from ATNPs could generate new hybridized modes (strong local field in the vicinity of Dy〈sup〉3+〈/sup〉 ions) shifted with respect to the single type of NPs resonance. HRTEM images showed the existence of both Ag and titania NPs inside the glass matrix. Glasses containing ATNPs exhibited anatase phase with (103) and (112) nanocrystalline lattice plane orientation. Proposed glass system may be useful for the development of solid state laser and photonic devices.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Dapeng Zhou, Jürgen Malzbender, Yoo Jung Sohn, Olivier Guillon, Robert Vaßen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During the last decade, Suspension Plasma Spraying (SPS) attracted a lot of interest as an alternative process to produce columnar Thermal Barrier Coatings (TBCs). In this study, columnar TBCs were deposited with SPS. After spraying, samples were isothermally annealed at 1373 K for 1 h, 3 h, 10 h and 50 h, respectively. Microstructures and mechanical properties of the ceramic coatings were investigated as a function of annealing time. Annealing resulted in healing of micro-cracks, coarsening of pores, growth of domain size, companied with a decrease of porosity within columns. The change of coating microstructure led to change of mechanical properties. In addition, residual stress in SPS coatings was also investigated. Furthermore, as-sprayed coatings and pre-annealed coatings were subjected to burner rig tests. Short time pre-annealing allowed to enhance thermal cycling lifetime of such SPS coatings. The thermal cycling results were related to microstructure modifications of coatings.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Xuejin Yang, Bin Li, Duan Li, Changwei Shao, Changrui Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the high-temperature performance of wave-transparent materials especially for the high-speed aircrafts application, filament winding combined with sol-gel method was adopted to the fabrication of unidirectional silicon nitride fiber reinforced silica matrix composites. The mechanical properties and the interface evolution at high temperatures were investigated. The results show that the composite sintered in N〈sub〉2〈/sub〉 maintains a flexural strength of 210MPa at up to 1200°C, while its counterpart prepared in air experiences a dramatic reduction to about 73MPa. The degradation is due to the partial oxidation of silicon nitride fibers at the fiber matrix interface. Besides, it is also notable that the bending strength of these two composites undergoes a similar growth from about 160 to 210MPa when tested under 900°C, which can be explained by the release of thermal stress on the silicon nitride fibers.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Wei Hao, Qihui Zhang, Chen Xing, Fangwei Guo, Meiyu Yi, Xiaofeng Zhao, Ping Xiao〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Y〈sub〉2〈/sub〉SiO〈sub〉5〈/sub〉 is a promising material for the thermal barrier coatings due to its low thermal conductivity, high temperature stability and exceptional resistance for molten silicate attack. However, it suffers low fracture toughness and low coefficient of thermal expansion compared with yttria-stabilized zirconia (YSZ). In this study, a composite coating approach, i.e., incorporating YSZ into Y〈sub〉2〈/sub〉SiO〈sub〉5〈/sub〉 coating, was employed to overcome those limitations. The double-layered Y〈sub〉2〈/sub〉SiO〈sub〉5〈/sub〉-YSZ/YSZ coatings were fabricated using atomospheric plasma spraying and tested under thermal cycling at 1150 °C. The phase compositions, microstructure, mechanical properties and the failure behavior were evaluated. It was found that the amorphous phase during spraying would crystallize at high temperature accompanied by volume shrinkage, leading to cracks and spallation in the coating. With YSZ addition, the composite coatings exhibited a much longer lifetime than the single phase Y〈sub〉2〈/sub〉SiO〈sub〉5〈/sub〉 coating due to a lower volume shrinkage and enhanced toughness.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Jian Xu, Baofu Hu, Chao Xu, Jian Wang, Bingguo Liu, Hui Li, Xinliang Wang, Baoli Du, Yuxuan Gong〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Good thermal dispersion is essential for phosphors used in laser-lighting applications. Luminescent films naturally show better thermal dispersion than bulk phosphor because the distance to the supporting substrate is shorter, which facilitates heat dissipation. However, the underlying mechanism for luminescence saturation in films is still unclear. In addition, the synthesis of luminescent films always involves the use of carbon-rich organic materials, which can introduce both pores and carbon residues. Here, we present a facile sol–gel route to synthesize YAG:Ce thick films suitable for laser lighting applications. Inorganic aluminum hydroxides are used as gelling agent, which solves the carbon residue problem. A series of YAG:Ce films of different thicknesses was produced at relatively low temperature (975 °C). The YAG:Ce film shows no luminescence saturation under 4.1 W blue laser excitation. This means this approach represents a strong potential candidate for applications like automotive headlamps and many other devices.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): João Vitor Campos, Isabela Reis Lavagnini, Rafael Vieira de Sousa, Julieta Adriana Ferreira, Eliria Maria de Jesus Agnolon Pallone〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heterogeneous grain size distributions due to cathodic reduction of samples sintered by flash sintering (FS) are a recurring problem. Herein, we present an experimental setup for FS with refined control of the process parameters, especially the electric current density, to control the power peak that could reduce the grain size heterogeneity of sintered materials. The real-time control of the equipment enabled the development of a Multi-Step Flash Sintering (MSFS) process. This technique involves varying the maximum current density at the onset of the abrupt shrinkage of the sample during the flash phenomenon, smoothing the shrinkage and power density curves, avoiding power peak and allowing its control in real time. Tetragonal stabilised zirconia (3YSZ) was sintered in this equipment by both FS and MSFS. Preliminary results of this study were promising in terms of density control and improvement of grain size homogeneity.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Kang Guan, Haitao Ren, Qingfeng Zeng, Zhiqiang Feng, Jianqing Wu, Zhenya Lu, Pinggen Rao, Yangfang Cheng, Zhenyuan Gong, Yougen Yu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous ceramics are numerically constructed based on the convexity of the void phase: microstructures with convex pores are representative of isolated or randomly overlapping spherical pores, while particulate materials with non-convex pores are composed of randomly overlapping, partial overlapping or partially sintered solid spheres. Finite element simulations show that, given the porosity, thermal conductivities and elastic moduli for convex porosity are larger than the values for non-convex pores. These conditions are not well described by solely porosity. By contrast, this study proposes a new microstructural parameter, 〈lp2〉/(〈ls2〉+〈lp2〉), to estimate thermal conductivities and elastic moduli for both convex and non-convex pores. 〈ls2〉 and 〈lp2〉 are respectively mean-square solid chord length and mean-square pore chord length of cross-sections, which can be conveniently extracted from SEM images combined with chord length distributions of solid and void.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Tianrang Yang, Hailei Zhao, Mengya Fang, Konrad Świerczek, Jie Wang, Zhihong Du〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉La〈sub〉9.67〈/sub〉Si〈sub〉6-x〈/sub〉Cu〈sub〉x〈/sub〉O〈sub〉26.5-x〈/sub〉 (LSC, x = 0, 0.1, 0.3 and 0.5) are synthesized by a citric-nitrate method. Substitution Si with Cu promotes the densification process of silicate apatite. Unit cell parameters and volume increase linearly with Cu content. The Rietveld refinement reveals a much more distorted (Si,Cu)O〈sub〉4〈/sub〉 tetrahedra in the oxygen stoichiometric La〈sub〉9.67〈/sub〉Si〈sub〉5.5〈/sub〉Cu〈sub〉0.5〈/sub〉O〈sub〉26〈/sub〉 sample. The structural observation from high temperature XRD implies a second-order phase transition in La〈sub〉9.67〈/sub〉Si〈sub〉5.5〈/sub〉Cu〈sub〉0.5〈/sub〉O〈sub〉26〈/sub〉. Cu-doping decreases the activation energy of oxygen ion conduction and increases the conductivity of LSC materials in the temperature range of 550–800 °C. La〈sub〉9.67〈/sub〉Si〈sub〉5.5〈/sub〉Cu〈sub〉0.5〈/sub〉O〈sub〉26〈/sub〉 shows the conductivity values of 29.3 and 12.3 mS cm〈sup〉−1〈/sup〉 at 800 °C and 650 °C, respectively. The oxygen ion transference number of La〈sub〉9.67〈/sub〉Si〈sub〉5.5〈/sub〉Cu〈sub〉0.5〈/sub〉O〈sub〉26〈/sub〉 is higher than 0.99. These attractive properties make the La〈sub〉9.67〈/sub〉Si〈sub〉5.5〈/sub〉Cu〈sub〉0.5〈/sub〉O〈sub〉26〈/sub〉 a promising oxygen ion conducting electrolyte for applications of solid oxide fuel cells, oxygen sensors, oxygen separation membranes, 〈em〉etc.〈/em〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Hai Jiang, Xiao-Hong Wang, Wen Lei, Gui-Fen Fan, Wen-Zhong Lu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of two-step sintering on the microstructure, mechanical and thermal properties of aluminum nitride ceramics with Yb〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and YbF〈sub〉3〈/sub〉 additives were investigated. AlN samples prepared using different sintering methods achieved almost full density with the addition of Yb〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–YbF〈sub〉3〈/sub〉. Compared with the one-step sintering, the grain sizes of AlN ceramics prepared by the two-step sintering were limited, and the higher flexural strength and the larger thermal conductivity were obtained. Moreover, the electrochemical impedance spectroscopy of AlN ceramic was associated with thermal conductivity by analyzing the defects and impurities in AlN ceramics. The fitting grain resistance and the activation energy for the grain revealed the lower concentrations of aluminum vacancy in the two-step sintered AlN ceramics, which resulted in the higher thermal conductivity. Thus, mechanical and thermal properties for AlN ceramics were improved with Yb〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and YbF〈sub〉3〈/sub〉 additives sintered using two-step regimes.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Gregory N. Morscher, Ryan Maxwell〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Acoustic emission, electrical resistance, and surface optical techniques were used to monitor matrix cracking and fiber-breakage during fatigue in tension for [0/90]2s SiC-based laminate composite single-notch specimens. Acoustic emission sensors were positioned in several locations including on the edge of the specimen which enabled location of events through the width and the location of internal tunnel-type cracks. Surface optical techniques, including digital image correlation, enabled the extent of surface crack growth. From these two sets of data a simple circuit could be constructed of the different damaged and undamaged regions in the region of the notch that was in good agreement with the change in electrical resistance, thus establishing a correlation with change in ER and damage development. The unique placement of AE sensors on the edge of the specimen also enabled the capture and location of what are believed to be fiber failure events prior to ultimate failure.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Iñigo Garbayo, Federico Baiutti, Alex Morata, Albert Tarancón〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉New emerging disciplines such as Nanoionics and Iontronics are dealing with the exploitation of mesoscopic size effects in materials, which become visible (if not predominant) when downsizing the system to the nanoscale. Driven by the worldwide standardisation of thin film deposition techniques, the access to radically different properties than those found in the bulk macroscopic systems can be accomplished. This opens up promising approaches for the development of advanced micro-devices, by taking advantage of the nanostructural deviations found in nanometre-sized, interface-dominated materials compared to the “ideal” relaxed structure of the bulk. A completely new set of functionalities can be explored, with implications in many different fields such as energy conversion and storage, or information technologies. This manuscript reviews the strategies, employed and foreseen, for engineering mass transport properties in thin film ceramics, with the focus in oxide ionic and mixed ionic-electronic conductors and their application in micro power sources.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Christoph Settgast, Yvonne Ranglack-Klemm, Jana Hubalkova, Martin Abendroth, Meinhard Kuna, Horst Biermann〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Open-cell ceramic foams are used as filters in casting processes of molten metal to reduce the amount of non-metallic inclusions. These filters are exposed to high temperatures and loadings, sometimes for a longer time. Therefore, the dimensional stability has to be considered, which suffers from inelastic deformations, in particular creep deformations.〈/p〉 〈p〉A recent work of the authors describes the creep deformation behaviour of such foam structures using an experimental-numerical approach based on bulk material creep tests. Now, the results of this prediction are validated by creep curves of real foam samples. This comparison shows a good accordance for the considered parameters (load, temperature, time, and creep phase).〈/p〉 〈p〉Moreover, the influences of different structural parameters on the elastic foam stiffness and foam creep resistance are investigated. The relative foam density has the greatest impact, followed by uniaxial pore stretching in one direction and strut shape, whereas polydispersity has only a very small effect.〈/p〉 〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Yong-Hyeon Kim, Young-Wook Kim, Kwang-Young Lim, Seoung-Jae Lee〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two different SiC ceramics with a new additive composition (1.87 wt% Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–Sc〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–MgO) were developed as matrix materials for fully ceramic microencapsulated fuels. The mechanical and thermal properties of the newly developed SiC ceramics with the new additive system were investigated. Powder mixtures prepared from the additives were sintered at 1850 °C under an applied pressure of 30 MPa for 2 h in an argon or nitrogen atmosphere. We observed that both samples could be sintered to ≥99.9% of the theoretical density. The SiC ceramic sintered in argon exhibited higher toughness and thermal conductivity and lower flexural strength than the sample sintered in nitrogen. The flexural strength, fracture toughness, Vickers hardness, and thermal conductivity values of the SiC ceramics sintered in nitrogen were 1077 ± 46 MPa, 4.3 ± 0.3 MPa·m〈sup〉1/2〈/sup〉, 25.4 ± 1.2 GPa, and 99 Wm〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 at room temperature, respectively.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Weizeng Yao, Jialiang Zhang, Xuemei Wang, Chunming Zhou, Xue Sun, Jie Zhan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Research for high-performance lead-free piezoelectric materials has become an urgent issue from the environmental concern. Very limited attempts on two-step sintering had been made so far. In this study, (K〈sub〉0.45〈/sub〉Na〈sub〉0.55〈/sub〉)〈sub〉0.98〈/sub〉Li〈sub〉0.02〈/sub〉Nb〈sub〉0.76〈/sub〉Ta〈sub〉0.18〈/sub〉Sb〈sub〉0.06〈/sub〉O〈sub〉3〈/sub〉 ceramics were prepared by both conventional sintering and two-step sintering. Piezoelectric properties, microstructure and domain structure were found to change significantly with sintering methods and sintering conditions. Two-step sintering was performed in the way that temperature is first quickly raised to 1180 °C, kept for 1 min, then immediately cooled down to 1120 °C and maintained for a desired time length. The effects of dwelling time on piezoelectric performance and microstructure as well as domain structure were investigated. High piezoelectric properties of 〈em〉d〈/em〉〈sub〉33〈/sub〉 = 455 pC/N, 〈em〉k〈/em〉〈sub〉p〈/sub〉 = 0.54 and 〈em〉k〈/em〉〈sub〉33〈/sub〉 = 0.67 were obtained in a ceramic prepared under the dwelling time of 20 h. This ceramic also possesses a very good piezoelectric thermal-ageing stability over −50 °C–150 °C. Further investigation reveals that this ceramic has a quite uniform grain-size distribution with the average grain size of about 12 μm in microstructure and shows domain patterns of simple parallel stripes with a hierarchical nanodomain structure appearing inside some of broad stripes. The observed excellent piezoelectric performance is considered to associate closely with the unique domain structure.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Ingo Jürgen Markel, Jürgen Glaser, Martin Steinbrück, Hans Jürgen Seifert〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Si-C-N ceramic was synthesized by pyrolysis of the polysilazane Ceraset〈sup〉®〈/sup〉 PSZ 10 and PSZ 20. The preceramic polymer was crosslinked by gradual heating up to 300 °C and pyrolyzed at temperatures from 1000 °C to 1500 °C in flowing Ar- and N〈sub〉2〈/sub〉-containing atmospheres, respectively. The influence of the pyrolysis temperature and the nitrogen partial pressure (p〈sub〉N2〈/sub〉) on the high-temperature stability, phase reactions and crystallization behavior was investigated by STA, XRD and SEM/EDX. Additionally, gaseous pyrolysis- and reaction products were analyzed by on-line mass spectrometry. The CALPHAD (CALculation of PHAse Diagrams) method was used to calculate pyrolysis products and high-temperature phase stabilities as a function of temperature and p〈sub〉Ar〈/sub〉/p〈sub〉N2〈/sub〉. It is shown that the observed experimental findings are quantitatively confirmed and explained by the modelling.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Florimond Delobel, Sébastien Lemonnier, Élodie Barraud, Julien Cambedouzou〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of Spark Plasma Sintering pressure and temperature on the evolution of the phase composition of two sources of 〈em〉β〈/em〉-SiC ceramic were studied based on X-ray diffraction and Raman scattering measurements. A commercial powder and a powder derived from a preceramic polymer precursor were chosen, and the investigation was undertaken in the [1850-2200 °C] temperature range and in the [17–127 MPa] pressure range. Analyses revealed that the 3C-6H phase transition depends on sintering pressure, which is shown to stabilize the cubic phase. The stability domains of the cubic phase as a function of sintering P and T were determined for both powdery precursors and revealed that the cubic phase stability is also linked to the nature of powdery precursor and in particular to its crystallinity state. The improvement of cubic phase stability at higher temperature by applying pressure allows sintering 〈em〉β〈/em〉-SiC ceramic with high density.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Branislav Dzepina, Daniel Balint, Daniele Dini〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The incorporation of an efficient contact mechanics algorithm into a phase field sintering model is presented. Contact stresses on the surface of arbitrarily shaped interacting bodies are evaluated and built into the model as an elastic strain energy field. Energy relaxation through deformation is achieved by diffusive fluxes along stress gradients and rigid body motion of the deforming particles maintain contact between the particles. The proposed model is suitable for diffusion deformation mechanisms occurring at stresses below the yield strength of a defect-free material; this includes Nabarro-Herring creep, Coble creep and pressure-solution. The effect of applied pressure on the high pressure-high temperature (HPHT) liquid phase sintering of diamond particles was investigated. Changes in neck size, particle coordination and contact flattening were observed. Densification rates due to the externally applied loads were found to be in good agreement with a new theory which implicitly incorporates the effect of applied external pressure.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Heat and Mass Transfer, Volume 130〈/p〉 〈p〉Author(s): Shengxiang Deng, Changda Nie, Haojie Jiang, Wei-Biao Ye〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Embedded fin in phase change materials (PCMs) is one of the most efficient methods to enhance the heat transfer between the PCM and heat transfer fluid (HTF). An appropriate arrangement of the fins plays significant role to design a highly efficient latent heat thermal energy storage (LHTES) unit. The aim of this study is to find the most efficient arrangement of fins to accelerate the charging rate. A two-dimensional numerical model based on finite volume method (FVM) was developed with considering natural convection and the calculation results were validated with experimental data. The heat transfer characteristics of LHTES unit with different fins arrangements were firstly explored. These include no fins, straight fins, angled fins, lower fins and upper fins. Then, the effects of fins number (〈em〉N〈/em〉), dimensionless fins length (〈em〉l〈/em〉), heat transfer fluid temperature (〈em〉T〈/em〉〈sub〉w〈/sub〉) and outer tube material on melting performance for four arrangements were studied. In addition, the best type of arrangements to increase the efficiency of heat exchanger was suggested. The performance enhancement of LHTES through fins configuration were quantitatively described based on complete melting time and heat storage capacity, and the conclusions are arrived as follows: when 〈em〉N〈/em〉 ≤ 6, the optimum arrangement is the lower fins, while it is the angled fins when 〈em〉N〈/em〉 〉 6. For 〈em〉N〈/em〉 = 6, only 〈em〉l〈/em〉 could change the optimum arrangement of fins. At 〈em〉l〈/em〉 equals 0.5 and 0.95, the optimum arrangement is angled case. While at 〈em〉l〈/em〉 = 0.75, the optimum arrangement is lower case. It is also found that the heat storage capacity of lower fins configuration is minimal compared to other three configurations.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Biology and Biochemistry, Volume 128〈/p〉 〈p〉Author(s): J.M. Kranabetter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Forest floor carbon (C) sequestration has been negatively correlated with manganese (Mn) availability, possibly due to reduced efficacy of Mn-peridoxase enzymes produced by Agaricomycete fungi. I examined a soil C and Mn dataset from a podzolization gradient, along with fungal sporocarp Mn concentrations, to potentially corroborate this finding. An inverse power relationship between soil C and soil Mn content across temperate rainforests was confirmed, which provides further evidence of a Mn bottleneck in C turnover. Average Mn concentrations of saprotrophic sporocarps were greater than those of ectomycorrhizal fungi, and displayed a similar inverse correlation with increasing soil C. The absence or limited effectiveness of select saprotrophic fungi across Mn-depleted forest soils may be one mechanism behind impeded turnover of recalcitrant organic matter.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Biology and Biochemistry, Volume 128〈/p〉 〈p〉Author(s): Charles R. Warren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phospholipids are isolated from crude lipid extracts by silica solid phase extraction (SPE), but for soils we don't know if phospholipids are the only fatty acid-based lipids present in the polar lipid fraction. Lipids extracted from three soils were fractionated with a silica SPE protocol commonly used for soils, with “neutrals” eluted by chloroform, “glycolipids” eluted by acetone, and “phospholipids” eluted by methanol. Fatty acid-based lipids were identified and quantified by liquid chromatography-mass spectrometry. Phospholipids were recovered in the methanol fraction, but this fraction also included betaine lipids. In two soils the methanol fraction was 3–6% betaine lipid while in one soil betaine lipids accounted for 48% of lipids in the methanol fraction. Clearly the fraction obtained by eluting lipids from silica with methanol is not purely phospholipid but can contain significant amounts of other polar lipids.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: February–March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of the European Ceramic Society, Volume 39, Issues 2–3〈/p〉 〈p〉Author(s): Mattia Biesuz, Vincenzo M. Sglavo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Flash sintering is a novel densification technology for ceramics, which allows a dramatic reduction of processing time and temperature. It represents a promising sintering route to reduce economic, energetic and environmental costs associated to firing. Moreover, it allows to develop peculiar and out-of-equilibrium microstructures.〈/p〉 〈p〉The flash process is complex and unusual, including different simultaneous physical and chemical phenomena and their understanding, explanation and implementation require an interdisciplinary approach from physics, to chemistry and engineering. In spite of the intensive work of several researchers, there is still a wide debate as for the predominant mechanisms responsible for flash sintering process.〈/p〉 〈p〉In the present review, the most significant and appealing mechanisms proposed for explaining the “flash” event are analyzed and discussed, with the aim to point out the level of knowledge reached so far and identify, at least, possible shared theories useful to propose future scientific activities and potential technological implementations.〈/p〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Scripta Materialia, Volume 162〈/p〉 〈p〉Author(s): Mageshwari Komarasamy, Tianhao Wang, Kaimiao Liu, Luis Reza-Nieto, Rajiv S. Mishra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Modification of a coarse B2 phase and realization of hierarchical multi-phase microstructures were achieved in an Al〈sub〉0.5〈/sub〉CrFeCoNi complex concentrated alloy (CCA) using high-temperature severe plastic deformation (HTSPD). Under HTSPD conditions, a thermodynamically stable B2 phase dissolved, while a thermodynamically unstable coarse Al〈sub〉3〈/sub〉Ni phase formed. Al supersaturation in the matrix after HTSPD led to the formation of fine B2 precipitates during the subsequent aging treatment. The combination of Al〈sub〉3〈/sub〉Ni for enhanced work hardening and fine B2 precipitates for strength resulted in excellent strength-ductility of 1400 MPa and 20%.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359646218306523-ga1.jpg" width="415" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): G. Gorni, M.J. Pascual, A. Caballero, J.J. Velázquez, J. Mosa, Y. Castro, A. Durán〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The crystallization mechanism of LaF〈sub〉3〈/sub〉 in sol-gel oxyfluoride glass-ceramics in the system SiO〈sub〉2〈/sub〉-LaF〈sub〉3〈/sub〉 has been studied using DTA, XRD, FTIR, HRTEM and NMR. Based on classical calculations of non-isothermal DTA curves involving Ozawas's plots, a diffusion-controlled process should be responsible for the fluorides crystallization similarly to that obtained for melt-quenching oxyfluoride glass-ceramics. Therefore, an increase of the crystal size and fraction is expected when increasing the time and/or temperature of the treatment. Nevertheless, XRD, FIR, HRTEM and NMR demonstrated that neither bigger crystals nor higher crystal fraction are obtained for treatment times longer than 1 min at 550 °C. However, further heat treatment causes that the structural order of the crystals is lost. On the other hand, typical fluorides crystallization temperatures (~300 °C) in sol-gel materials are much lower than T〈sub〉g〈/sub〉 of the matrix (~1130 °C) thus being very different to what observed for oxyfluoride glasses prepared by melt-quenching. The proposed crystallization mechanism is a fast process that occurs when crystallization temperature is reached. This behavior is explained as a chemical reaction from the xerogels, followed by the fast precipitation of the nanocrystals without energy barrier. The nanocrystals are unstable in the surrounding SiO〈sub〉2〈/sub〉 matrix for aging at crystallization or higher temperatures. These treatments lead to a dissolution process, favored by the compositional gradient between matrix and crystals, which drive the material to reach the equilibrium.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Jürn W.P. Schmelzer, Alexander S. Abyzov, Vladimir M. Fokin, Christoph Schick〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉General relations for the dependence of the thermodynamic driving force of crystallization and the specific interfacial energy melt-crystal of critical crystal clusters on temperature and pressure are derived. Its application to the analysis of experimental data on crystal nucleation seems to support at a first glance a proposal by Kauzmann on the existence of a pseudo-spinodal curve in melt-crystallization. Provided this assumption is true, Kauzmann temperature (and for pressure-induced nucleation, the Kauzmann pressure) cannot be reached by a metastable liquid due to intensive crystallization processes occurring in its vicinity. However, such suggestion cannot be retained taking into account the kinetic terms (diffusion coefficients, viscosity) in the expression for the nucleation rate. The absence of a pseudo-spinodal in melt-crystallization can be verified also in an alternative way by considering the characteristic time scales of crystallization and relaxation. Finally, it is shown that the phenomenon denoted commonly as Kauzmann paradox is merely an untypical as compared to normal conditions type of behavior. Neither in its original formulation nor in its consequences it results in any contradictions with basic laws of nature. They are prevented either by normal (not associated with a pseudo-spinodal) crystallization or a conventional glass transition.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): J. Gilabert, M.P. Gómez-Tena, V. Sanz, S. Mestre〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The effect of a post-synthesis thermal treatment on CoCr〈sub〉2−2Ψ〈/sub〉Al〈sub〉2Ψ〈/sub〉O〈sub〉4〈/sub〉 (0.0 ≤ Ψ ≤ 1.0) ceramic pigments synthesized by Solution Combustion Synthesis (SCS) has been studied. As-synthesized SCS pigments were treated at two different calcination temperatures (800 °C and 1000 °C) to study changes in mineralogy, microstructure and thermal behaviour, as well as their effect over the colouring power.〈/p〉 〈p〉Spinel-type 〈em〉Fd〈/em〉-3〈em〉m〈/em〉 crystalline structure was developed in all cases. Nevertheless, crystallinity parameters were highly affected by both analysed processing parameters: composition (Ψ) and post-synthesis calcination temperature (T〈sub〉c〈/sub〉). A Cr(III) enrichment along with T〈sub〉c〈/sub〉 increase favoured ion rearrangement to promote sample crystallization and crystallite growth. Fast kinetics of SCS makes Al-rich spinels with transition metals difficult to be synthesized. The application of a secondary thermal treatment resulted in a favourable evolution towards a well-crystallized structure. Lattice parameter did not seem to be affected by T〈sub〉c〈/sub〉, although it evolved indeed with composition. From a microstructural point of view, as-synthesized pigments were foamy, with a very low bulk density and nanometric grain size. After the thermal treatment, larger grain sizes were obtained, especially for the samples richer in Al and treated at higher T〈sub〉c〈/sub〉.〈/p〉 〈p〉All pigments developed intense colours in a transparent glaze without showing heterogeneities, indicating a stable behaviour against glazing process. Glaze colour evolved from green to perfectly blue shades, indicating an important dependence on composition. Nevertheless, colouring power seemed to be rather affected by calcination process.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Radiation Measurements, Volume 119〈/p〉 〈p〉Author(s): Alessio Parisi, Luana de Freitas Nascimento, Olivier Van Hoey, Patrice Mégret, Hisashi Kitamura, Satoshi Kodaira, Filip Vanhavere〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium fluoride thermoluminescent radiation detectors with different dopant concentrations (〈sup〉7〈/sup〉LiF:Mg,Ti and 〈sup〉7〈/sup〉LiF:Mg,Cu,P) were exposed to 〈sup〉1〈/sup〉H and 〈sup〉4〈/sup〉He ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in order to investigate their response to energetic light charged particles. Computer simulations with the Monte Carlo code PHITS were performed for a better interpretation of the experimental data. The results were compared with literature efficiency data and with the results of a recently developed microdosimetric efficiency model. In case of the main peak signal of 〈sup〉7〈/sup〉LiF:Mg,Ti detectors, the determined efficiency values are in good agreement with previous investigations. Discrepancies in the efficiency of high temperature signal due to well-known non-linearity effects are reported. For 〈sup〉7〈/sup〉LiF:Mg,Cu,P detectors, an anomalous thermoluminescence behavior in the low temperature part of the signal was found and discussed. Depending on the light quantification process, differences up to 30% in the dose assessment can be obtained, affecting also the relative efficiency determination process. An explanation of this phenomenon as a consequence of local migration of the charged carriers between the low temperature peaks and the main peak is presented. The implications of these findings on the use of LiF:Mg,Cu,P detectors in radiation environments characterized by the presence of 〈sup〉1〈/sup〉H and 〈sup〉4〈/sup〉He ions (i.e. space and proton therapy) are discussed. In order to avoid the occurrence of this anomalous behavior, it is advised to pre-heat the detectors after energetic light particle exposures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 31 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Power Sources, Volume 408〈/p〉 〈p〉Author(s): Guoping Chen, Xiong Song, Suqing Wang, Xinzhi Chen, Haihui Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-sulfur (Li〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉S) batteries are attractive candidates for advanced energy storage devices. However, the low utilization of sulfur and the severe “shuttle effect” hinder the commercialization of Li〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉S batteries. Herein, we design an ultra-thin and lightweight two-dimensional (2D) molybdenum nitride nanosheets layer to modify Celgard (denoted as MoN〈sub〉x〈/sub〉/Celgard) separator to promote the electrochemical performance of Li〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉S batteries. Benefiting from the 2D polar molybdenum nitride nanosheets, the obtained molybdenum nitride layer can effectively suppress the shuttle effect via the synergistic effect of structural confinement and chemical absorption. Meanwhile, molybdenum nitride nanosheets layer possesses metallic and catalytic characteristics, which are beneficial for high sulfur utilization. Therefore, the Li〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉S batteries using MoN〈sub〉x〈/sub〉/Celgard separator with multifunction exhibit high capacity and outstanding cycling performance. It delivers a high discharge capacity of 1298 mA h g〈sup〉−1〈/sup〉 at 0.1C and sustain a capacity of 566 mA h g〈sup〉−1〈/sup〉 after 500 cycles at 0.5C, corresponding with the capacity fading rate of only 0.063% per cycle.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Geoderma, Volume 337〈/p〉 〈p〉Author(s): R. Calvelo Pereira, M. Camps Arbestain, F.M. Kelliher, B.K.G. Theng, S.R. McNally, F. Macías, F. Guitián〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have investigated the effect of supercritical drying (SD) on the porosity and the BET-N〈sub〉2〈/sub〉 specific surface area (SSA) of five allophane-rich and three non-allophanic topsoils. The contribution of organic matter (OM) and short-range ordered (SRO) constituents to the nanoscale porosity (〈100 nm size) and SSA was also evaluated following chemical treatments to oxidise OM and then remove the SRO phase. The average pore volume and SSA of the soils, measured after SD, are greater than the values obtained after air drying. For soils that are rich in SRO constituents, oxidation of OM leads to an increase in SSA. This observation is attributed to the unblocking of pore necks previously covered by OM, while the subsequent removal of SRO constituents causes a sharp decrease in SSA. The SRO constituents containing oxalate-extractable Al, are the major contributors to the SSA of the inorganic fraction. Besides confirming that SD can help preserve the nanoscale porosity of allophane-rich soils, the results highlight the contribution of SRO constituents to the SSA of soils and their ability to accumulate OM.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Joanna Pisarska, Marta Sołtys, Joanna Janek, Agata Górny, Ewa Pietrasik, Tomasz Goryczka, Wojciech A. Pisarski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxyfluoride lead-based and lead-free germanate glasses were heat-treated in order to fabricate transparent glass-ceramics. Cubic β-PbF〈sub〉2〈/sub〉 nanocrystals are well formed during crystallization of lead germanate glass. The up-conversion luminescence spectra of Er〈sup〉3+〈/sup〉 ions in lead germanate glass-ceramic system are enhanced significantly due to partial incorporation of the optically active ions into fluoride crystalline phase. These effects are not significant in oxyfluoride lead-free germanate glass after heat treatment process. The crystallization of barium gallo-germanate glass with BaF〈sub〉2〈/sub〉 is more complex and the presence of four crystalline phases BaF〈sub〉2〈/sub〉, BaO, Ba〈sub〉3〈/sub〉Ga〈sub〉2〈/sub〉Ge〈sub〉4〈/sub〉O〈sub〉14〈/sub〉 and GeO〈sub〉2〈/sub〉 was verified by X-ray diffraction measurements.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil and Tillage Research, Volume 186〈/p〉 〈p〉Author(s): Márcio R. Nunes, Eloy A. Pauletto, José E. Denardin, Luis E.A. S. Suzuki, Harold M. van Es〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tillage and no-tillage result in different soil mechanical responses which in turn may affect crop growth. Better understanding of soil compressive behavior, therefore, is relevant for the assessment of tillage practices in agricultural systems. We studied the change in soil compressive properties and their relationship with soil physical attributes and plant growth through a chisel tillage chronosequence in a Nitisol where soil was untilled after chiseling for 24 months, 18 months, 12 months, 6 months, and zero months, and was under continuous (12-year) NT. The effects were measured for three soil depth layers: 0 to 7-cm, 7 to 17-cm and 20 to 30-cm. Mechanical chiseling was found to reduce both the degree of compactness and the pre-compression pressure compared to continuous NT, but made the soil more susceptible to new compaction. The effects of chisel tillage generally persisted for a period of 12–24 months. The degree of compactness and soil pre-compression pressure were found to be strongly correlated, and were strongly correlated with other soil physical attributes (soil penetration resistance, soil macroporosity, and soil aggregate stability). They were negatively correlated with root length, root density, and root volume, as well as stalk diameter, linking soil structure indicators to plant growth. Our results also showed that soil compressive parameter values can be estimated based on other soil physical properties that influence plant growth. These findings have potential for studies of crop response to soil structure and soil compaction and could be used to aid in choosing optimal soil management practices, in order to reduce the risk of soil compaction, linking soil compressive behavior and soil physical conditions to plant growth.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 10 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Composites Science and Technology, Volume 168〈/p〉 〈p〉Author(s): Wancong Bian, Tong Yao, Ming Chen, Cheng Zhang, Tao Shao, Ying Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Epoxy resin has been widely used in electrical and electronics industries due to its excellent adhesion and insulating properties. However, the low thermal conductivity limits its application in the devices, especially under the working conditions of high frequency. In this work, the epoxy resin composites filled with binary fillers of dopamine modified micro-BN and KH550 modified nano-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 were fabricated and the thermal conductivities, dielectric losses and breakdown strengths in high frequency and electrical field of the composites were studied. A high thermal conductivity of 1.182 W m〈sup〉−1〈/sup〉K〈sup〉−1〈/sup〉 was realized in the composite with 22.5 wt% BN and 7.5 wt% Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, which was about 700% higher than neat epoxy resin. The results of breakdown experiments in high frequency and high voltage field showed that the positive effect of the thermal conductivity increase was greater than the negative effect of the dielectric loss increase, and the notably improved breakdown time of the composite was 406% higher than that of neat epoxy. The epoxy resin composites with high thermal conductivity and excellent dielectric strength could be a potential insulating material in the electrical and electronics industries.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 10 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Composites Science and Technology, Volume 168〈/p〉 〈p〉Author(s): Shashikant P. Patole, Muhamad F. Arif, S. Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon nanotubes (CNT) and graphene have been recognized as superior nanomaterials for high-performance, lightweight and multifunctional composites. However, non-uniform CNT/graphene dispersion within the polymer matrix, imperfect interphase between CNT/graphene and polymer matrix have hindered significant improvements in composite performance. In this study, we present a water-based grafting approach to produce polyvinyl alcohol (PVA) incorporated CNT buckypaper and CNT-graphene hybrid buckypaper composites with enhanced mechanical performance (tensile and fracture) and electrical conductivity. Our approach provides a wide range of composition for CNT (5–77 wt.%) and PVA matrix (23–95 wt.%) without compromising the uniformity of CNT dispersion and polymer matrix homogeneity. The composite buckypapers have lightweight with a density of 168 mg/cc (lighter than daily use copy papers having a density of 740 mg/cc). They show an electrical conductivity of 82 S/cm which is five orders higher than the neat PVA films (10〈sup〉−5〈/sup〉 S/cm) and three orders higher than the previous reports. Overall, 600% improvement in the Young's modulus and 80% improvement in the tensile strength with an optimum PVA loading is observed. They also exhibit a strong linear piezoresistive response. The water absorption changes their mechanical (tensile and Mode I fracture), electrical and piezoresistive performance. The cross-sectional fracture SEM images are used to understand the failure mechanisms. The results suggest that the developed approach would be an effective method for the fabrication of high-performance, lightweight, multifunctional composite buckypaper.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 10 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Composites Science and Technology, Volume 168〈/p〉 〈p〉Author(s): Spiridon Koutsonas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Resin rich zone along component edges is a common phenomenon during composites liquid infusion with the resin transfer moulding process. The challenge in the present work is to be able to predict the realistic race-track flow behaviour along a 90° edge in order to manufacture high-quality composites materials for aerospace or other applications. To that end, there is a lack of an advanced simulation tool capable to predict the manufacture of multi-layer textile composites. The issue of 2D, 3D racetrack prediction on this paper was investigated along a 90° edge for a composite textile. A novel numerical approach for a three-dimensional Finite Element Control/Volume modelling was developed in order to predict race-tracking permeability for any composite structure. The model was experimentally verified for a 2/2 twill carbon fibre geometry. All experiments and simulations used 1 bar pressure and 300 mPa s viscosity.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 10 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Composites Science and Technology, Volume 168〈/p〉 〈p〉Author(s): J. Cugnoni, R. Amacher, S. Kohler, J. Brunner, E. Kramer, C. Dransfeld, W. Smith, K. Scobbie, L. Sorensen, J. Botsis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thin-ply composites represent a promising approach to further improve the performance of carbon fibre composite structures thanks to their ability to delay the onset of matrix cracking and delamination up to the point of fibre dominated failure. However, this increased strength comes with a more brittle failure response which raises concerns on damage tolerance. Thus a careful material optimization is needed to address this trade-off. In this work, eight different formulations of thin-ply composites ranging from low modulus to high modulus carbon fibres are evaluated to understand the effects of the fibre and matrix constituents on the onset of damage and strength in unnotched tensile (UNT) tests of quasi isotropic laminates for ply thicknesses between 300 and 30 microns. The obtained experimental data are combined in master curve diagrams for simplified material selection process. It is observed that certain thin-ply composites with a ply thickness t 〈 134 μm can reach UNT strength corresponding to or approaching the ultimate strain of the fibres as well as UNT stress at onset of damage as high as 92% of the latter. Based on this knowledge, a novel aerospace grade toughened thin-ply composite system is developed which can reach a quasi-isotropic UNT strength above 1 GPa (〉95% of the fibre strain). The newly developed composite is further optimized to improve damage tolerance by toughening the resin and selected interfaces. The effect of those modifications on damage tolerance are evaluated through compression strength after impact (CAI) tests and open hole tensile tests (OHT). It is found that an optimized interlayer toughened thin-ply composite based on 68 microns plies of intermediate modulus fibre can reach both outstanding strength properties with comparable or better CAI and OHT strength compared to current aerospace grade composites.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 562〈/p〉 〈p〉Author(s): Parisa Moazzam, Giorgio Luciano, Amir Razmjou, Ehsan Akbari, Pavel G. Ul’yanov, Soumitro Mahanty〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The degree of available energy on a surface determines how a surface interacts with its surrounding environment such as corrosion. Current approaches to protection of Aluminum surfaces from corrosion mainly focus on adding an organic or inorganic layer to either act as a barrier from oxidant or scarifying to inhibit the corrosion. Altering the surface energy of Al on a molecular level is another alternative approach to efficiently modify the Al surface without the need for another thick expensive protective or scarifying materials. Herein, an attempt was made to understand how a molecular scale energy alteration improves the anticorrosion behavior of an aluminum surface. Two different surface engineering alteration strategies have been discussed; termed ALOSH and ALTSH modification. A variety of analytical instruments, i.e., FTIR, EDAX, XPS, SEM, AFM, WCA, and SFE measurement were used to systematically characterize the samples. Electrochemical impedance spectroscopy revealed that there are different resistances after the surface modifications. The trapping air resistance appeared in ALTSH is approximately 2.4 and 36 times higher than that of ALOSH and bare samples, respectively. The potentiostat analysis results showed that the mili inch per year value of coating for ALTSH was 0.012 while that of ALOSH was 0.507. It was also found that the low surface energy alteration without using inert molecules is not enough to render corrosion inhibition property, as it needs to have a protective energy barrier with no or minimal active electrochemical behavior.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775718311294-ga1.jpg" width="320" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Computational Physics, Volume 379〈/p〉 〈p〉Author(s): Takashi Shiroto, Naofumi Ohnishi, Yasuhiko Sentoku〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For more than half a century, most of the plasma scientists have encountered a violation of the conservation laws of charge, momentum, and energy whenever they have numerically solved the first-principle equations of kinetic plasmas, such as the relativistic Vlasov–Maxwell system. This fatal problem is brought by the fact that both the Vlasov and Maxwell equations are indirectly associated with the conservation laws by means of some mathematical manipulations. Here we propose a quadratic conservative scheme, which can strictly maintain the conservation laws by discretizing the relativistic Vlasov–Maxwell system. A discrete product rule and summation-by-parts are the key players in the construction of the quadratic conservative scheme. Numerical experiments of the relativistic two-stream instability and relativistic Weibel instability prove the validity of our computational theory, and the proposed strategy will open the doors to the first-principle studies of mesoscopic and macroscopic plasma physics.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Jie Zhang, Edwin Reynders, Guido De Roeck, Geert Lombaert〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Many civil engineering structures have a repetitive or quasi-periodic geometry. Such structures have clustered modes with closely spaced natural frequencies corresponding to mode shapes with similar wavelengths. Such modes may be difficult to distinguish in modal tests and lead to difficulties when pairing calculated and experimentally determined modal characteristics in vibration-based model updating. For repetitive structures, the free wave characteristics, i.e. propagation constants and free waves, can be used alternatively to characterize their dynamic behaviour. The free wave characteristics can therefore be used instead of modal characteristics as data features in model updating of repetitive structures. This paper investigates the feasibility of model updating of repetitive structures based on free wave characteristics. First, the identification of the free wave characteristics from the measured vibration responses of a periodic structure is investigated. A stabilization diagram is constructed to pick up the stable free waves. Second, model updating of repetitive structures is performed through a match of the calculated and experimentally identified free wave characteristics. A least-squares cost function is formulated and minimized using a gradient-based optimization algorithm. This algorithm requires the sensitivity of the free wave characteristics to the model parameters that need to be updated. The analytical expressions for the free wave sensitivities are therefore derived. The proposed model updating procedure is demonstrated and validated by a numerical case study involving a repetitive frame structure and by an experiment on a four-storey steel frame structure. The results confirm the feasibility of model updating based on free wave characteristics for repetitive structures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Timo Theurich, Johann Gross, Malte Krack〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A linear vibration absorber can be tuned to effectively suppress the resonance of a particular vibration mode. It relies on the targeted energy transfer into the absorber within a narrow and fixed frequency band. Nonlinear energy sinks (NES) have a similar working principle. They are effective in a much wider frequency band but generally only in a limited range of excitation levels. To design NES, their working principle must be thoroughly understood. We consider a particular type of NES, a small mass undergoing impacts and dry friction within a cavity of a base structure (vibro-impact NES or impact absorber). The nonlinear dynamic regimes under near-resonant forcing and resulting operating ranges are first revisited. We then investigate how off-resonant vibration modes and dissipation via impacts and dry friction contribute to the vibration suppression. Moreover, we assess the effectiveness of the impact absorber for suppressing multiple resonances in comparison to a linear tuned vibration absorber (LTVA) and a pure friction damper with the same mass.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Arian Bahrami〈/p〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Chuan-Xing Bi, Yuan Liu, Yong-Bin Zhang, Liang Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The equivalent source method (ESM)-based sound field separation technique has been successfully introduced into near-field acoustic holography as a preprocessing tool to eliminate the influence of disturbing sources or reflections from the opposite side of the array. In this paper, that technique is further extended in a sparsity framework, which makes it possible to take the advantage of the theory of compressive sensing to achieve reasonable separation accuracy with a limited number of spatial sampling points. In this study, three sparse bases are considered, including two existing bases that are suitable for spatially sparse and spatially extended sources, respectively, and a more flexible, redundant sparse basis that is constructed by combining the two sparse bases above, and the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉ℓ〈/mi〉〈mn〉1〈/mn〉〈/msub〉〈mo〉-〈/mo〉〈mtext〉norm〈/mtext〉〈/mrow〉〈/math〉 minimization is used to promote sparse solutions. Numerical simulation and experimental results demonstrate the validity of the proposed technique and show the superiority of the use of the redundant sparse basis. Besides, the effects of the relative strength of the target source to the disturbing source, the number of spatial sampling points and the signal-to-noise ratio on the separation accuracy are analyzed numerically.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): N.G.R. de Melo Filho, L. Van Belle, C. Claeys, E. Deckers, W. Desmet〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To enhance the sound insulation performance of double panel partitions at their mass-air-mass resonance frequency, novel compact and low-mass solutions are sought. This paper investigates the use of the locally resonant vibro-acoustic metamaterial concept as a possible solution. The metamaterial solution is applied to one panel of a double panel partition in order to enhance the sound transmission loss at the mass-air-mass resonance. To design the metamaterial solution and predict its sound transmission loss performance, an extension of the multiple reflection theory is proposed, incorporating the dynamic mass of a metamaterial panel. The latter is obtained from the metamaterial plate dispersion curves, calculated using finite element based unit cell modeling. The designed metamaterial solution is manufactured and its insertion loss is measured. The novel design outperforms the original double panel and an equivalent total mass double panel configuration in the targeted mass-air-mass resonance frequency region. The predictions obtained with the proposed method are in good agreement with the experimentally obtained results. This demonstrates the potential of the metamaterial solution to enhance the acoustic insulation at the mass-air-mass resonance and indicates that the proposed method allows a fast, simple and representative indication of their acoustic insulation performance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Zengwei Wang, Zhike Peng, Xi Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a method combining the structural modification method and an optimization algorithm is proposed for virtual decoupling of mechanical systems. The proposed method offers an alternative for virtual decoupling of mechanical systems in a very different way from the in-situ decoupling method, and performs better than the current virtual decoupling method for the relatively rigid links between subsystems. The relationship between structural modification and structural decoupling is first derived. A strategy for virtual decoupling of mechanical systems is presented, in which transfer functions of the modified system is used as an optimization object. Finally, the proposed method is validated by numerical and experimental case studies.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 3 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Sound and Vibration, Volume 442〈/p〉 〈p〉Author(s): Florian J. Krömer, Stéphane Moreau, Stefan Becker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The type of fan-blade skew used in axial fans has a strong impact on the sound field, the flow field and their interrelations. In this study, the sound emission and the velocity distributions of three low-pressure axial fans with a similar design point and forward-, backward- and unskewed fan blades are investigated. The forward skewed fan is found to have best aerodynamic performance as well as the least sound emission over a broad operating range. More detailed investigations at the fan design point, based on sound pressure spectra and beamforming evaluations, reveal very dominant subharmonic narrowband components and increased turbulence-ingestion noise for the backward- and the unskewed fan. Moreover, an increase in the meridional velocity in the tip region is observed for the forward-skewed fan, which weakens the tip-vortex formation. For the backward- and the unskewed fan however, a reduced meridional velocity in the tip region is found, which is an indicator of an intensified tip gap flow. Additionally, values of the turbulent kinetic energy are substantially increased for the backward- and the unskewed fan, which also hints at unsteady flow phenomena in the tip region. These flow processes are linked to the subharmonic narrowband sound emission. Finally, unsteady flow features in the tip region lead to an increase in turbulence-ingestion noise.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Jinghua Chen, Lu Zhang, Ning Yang, Mengyu Tian, Qiang Fu, Fenghua Tan, Chao Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Galectins are a family of galactoside-binding proteins with an affinity for β-galactosides, involved in mediating fundamental processes including development, inflammation, cell migration and apoptosis. Galectin-4 is a member of tendem-repeat galectins, plays vital roles in intestinal epithelial barrier. Here, one galectin-4 gene was captured in turbot (〈em〉Sm〈/em〉Lgals4) contains a 1197 bp open reading frame (ORF). In comparison to other species, 〈em〉Sm〈/em〉Lgals4 showed the highest similarity and identity both to large yellow croaker. The genomic structure analysis showed that 〈em〉Sm〈/em〉Lgals4 had conserved exons in the CRD domains compared to other vertebrate species. The syntenic analysis revealed that galectin-4 had the same neighboring genes across all the selected species, which suggested the synteny encompassing galectin-4 region during vertebrate evolution. Subsequently, 〈em〉Sm〈/em〉Lgals4 was widely expressed in all the examined tissues, with the highest expression level in intestine and the lowest expression level in skin. In addition, 〈em〉Sm〈/em〉Lgals4 was significantly down-regulated in intestine following both Gram-negative bacteria 〈em〉Vibrio anguillarum〈/em〉, and Gram-positive bacteria 〈em〉Streptococcus iniae〈/em〉 immersion challenge. Finally, the 〈em〉rSm〈/em〉Lgals4 showed strong binding ability to all the examined microbial ligands. Taken together, our results suggested 〈em〉Sm〈/em〉Lgals4 plays vital roles in fish intestinal immune responses against infection, but the detailed roles of galectin-4 in teleost are still lacking, further studies are needed to be carried out to characterize whether galectin-4 plays similar roles in teleost intestinal immunity.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Yanxiu Mo, Yunpeng Fan, Wen Fu, Wenting Xu, Shujuan Chen, Yuanhui Wen, Shaojun Liu, Liangyue Peng, Yamei Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Previous research has indicated that the small compound, SP600125, could induce polyploidy of fish cells, and has established a stable tetraploid cell line from diploid fish cells. In order to explore how fish cells maintain homeostasis under SP600125-stress 〈em〉in vitro〈/em〉, this study investigates impacts of SP600125-stress on intracellular pathways, as well as on regulation of the cellular homeostasis feedback in fish cells. Transcriptomes are obtained from the SP600125-treated cells. Compared with unigenes expressed in control group (crucial carp fin cells), a total of 2670 and 1846 unigenes are significantly upregulated and downregulated in these cells, respectively. Differentially expressed genes are found, which are involved in innate defense, inflammatory pathways and cell adhesion molecules-related pathways. The SP600125-stress enhances cell-mediated immunity, characterized by significantly increasing expression of multiple immune genes. These enhanced immune genes include the pro-inflammatory cytokines (IL-1β, TNF-ɑ, IL-6R), the adaptor signal transducers (STAT, IκBɑ), and the integrins (ɑ2β1, ɑMβ2). Furthermore, mitochondria are contributed to the cellular homeostasis regulation upon the SP600125-stress. The results show that acute inflammation is an adaptive and controlled response to the SP600125-stress, which is beneficial for alleviating toxicity by SP600125. They provide a potential way of breeding fish polyploidy induced by SP600125 in the future research.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Fish & Shellfish Immunology, Volume 84〈/p〉 〈p〉Author(s): Maciej Woźny, Kazimierz Obremski, Piotr Hliwa, Piotr Gomułka, Rafał Różyński, Paweł Wojtacha, Maciej Florczyk, Helmut Segner, Paweł Brzuzan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To investigate the effects of feed contamination with zearalenone (ZEN) at the current European Commission (EC) guidance value (2 mg⋅kg〈sup〉−1〈/sup〉 feed) on the growth and health of rainbow trout, we performed a long-term feeding trial under aquaculture conditions. It started with the external feeding of the fish larvae, and continued for 96 weeks, at which point the fish had reached market size. To assess the growth of fish and their feeding efficiency throughout this period, the fish were regularly weighed and measured, and their feed consumption was monitored. Additionally, to investigate potential health effects, after 72 weeks of the exposure to ZEN, the fishes' blood was analyzed for major hematological and biochemical indices, and their head kidney, spleen, and liver were examined for morphological, histopathological, cytological, and molecular changes. Finally, to gain insight into the metabolism and distribution of ZEN in fish, the content of free and glucuronidated forms of ZEN and its major metabolites was measured in the intestine, liver, and muscles of the exposed fish. The feed-borne exposure of rainbow trout to ZEN at a dose of 2 mg⋅kg〈sup〉−1〈/sup〉 feed resulted in higher feeding efficiency and growth rate, most probably due to the anabolic properties of the ZEN metabolite. Importantly for the consumers of fish, despite absorption and metabolism of ZEN in the digestive system of the fish that had been exposed for 72 weeks, the residuals of ZEN were not transferred to the fishes’ muscles, which rules out a potential risk to human health related to the consumption of fish meat. However, the increased growth of fish fed with the contaminated feed may come at some cost, as the exposure to ZEN was associated with modulation of key components of the adaptive and innate immune systems. Moreover, the trunk kidney of ZEN-fed fish showed massive inflammation that was likely caused by pathogen infection. These findings raise concerns about fish health under the current recommended EC guidance values.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Cristina Domínguez-Trujillo, Ana M. Beltrán, Maria D. Garvi, Alba Salazar-Moya, Julián Lebrato, Daniel J. Hickey, Jose A. Rodríguez-Ortiz, Paul H. Kamm, Clara Lebrato, Francisco García-Moreno, Thomas J. Webster, Yadir Torres〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, bacterial behavior on dense and porous titanium substrates is discussed. Porous titanium was fabricated by a space holder technique (using 50 vol%, NH〈sub〉4〈/sub〉HCO〈sub〉3〈/sub〉 with particle sizes between 250 and 355 μm). These substrates were coated by sulfonated PEEK (termed SPEEK). Characterization of the porous substrate was carried out using the Archimedes Method, Image Analysis, and three-dimensional X-ray Micro-Computed Tomography (including total and interconnected porosity, equivalent diameter, and pore shape factor), as well as mechanical characterization (specifically stiffness and yield strength). A detailed study was performed here to investigate the influence of substrate porosity on the adhesion and proliferation of 〈em〉E. coli〈/em〉, 〈em〉MRSA〈/em〉, and 〈em〉P. aeruginosa〈/em〉 (common causes of orthopedic device-associated infections). Bacterial colonization was examined in terms of the initial bacterial concentration, as well as bacterial adherence to and growth on the surface and inside the pores. Results suggest that fully dense titanium supported the least bacterial colonization, while the porous titanium promoted bacterial growth in the medium and inside the cavities. Furthermore, the SPEEK coating deposited onto the samples inhibited bacteria growth inside the porous materials. In this manner, this study showed for the first time that SPEEK could have potential antibacterial properties to offset the increase in bacteria growth commonly observed in porous materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897218312052-ga1.jpg" width="440" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Synthetic Metals, Volume 246〈/p〉 〈p〉Author(s): Dian Wang, Naveen Kumar Elumalai, Md Arafat Mahmud, Haimang Yi, Mushfika Baishakhi Upama, Robert Alexander Lee Chin, Gavin Conibeer, Cheng Xu, Faiazul Haque, Leiping Duan, Ashraf Uddin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two dimensional (2D) Transition Metal dichalcogenides have gained immense research attention in the recent years due to their superior opto-electronic properties and promising prospects in photonics and photovoltaic technologies. In this work, 2D Molybdenum disulphide (MoS〈sub〉2〈/sub〉) nanoflakes were incorporated as hole transport layers (HTLs) in inverted (p-i-n) perovskite solar cells (PSCs). MoS〈sub〉2〈/sub〉 nanoflakes were blended within the PEDOT:PSS layer together forming a hybrid HTL layer. The modified devices exhibited significant improvement in power conversion efficiency (PCE) and stability simultaneously. Compared to the control device, the efficiency enhancement of MoS〈sub〉2〈/sub〉 incorporated devices was around 18.5%. The MoS〈sub〉2〈/sub〉 nanoflake has improved the efficient charge extraction across the HTL layer reducing recombination at the interfaces, with a significantly lower electrode polarization and hysteresis. Impedance Spectroscopy (IS) analysis revealed that the MoS〈sub〉2〈/sub〉 blended PEDOT:PSS HTL increased the recombination resistance by 50%. The modified HTL based devices also exhibited high device stability retaining more than 95% of the initial PCE even after 4 weeks.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0379677918304466-ga1.jpg" width="238" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Xiaolong Cai, Lisheng Zhong, Yunhua Xu, Xin Li, Mingxin Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To improve the mechanical properties of the surface of iron-based alloys, a tungsten carbide-iron (WC-Fe) cemented carbide layer is produced on an alloy by adopting an isothermal annealing process, which was performed at 1050 °C for 4 h. By deeply etching the obtained sample, the morphologies of the WC ceramic grains in the WC-Fe hardmetal layer are characterized via scanning electron microscopy. The present results reveal three distinct morphologies consisting of rectangular, triangular prism and multi-layered shapes. Furthermore, the mechanical properties and fracture toughness of the WC-Fe layer are investigated through combined nanoindentation and Vickers indentation techniques. Nanoindentation testing is performed in a load range of 100 to 450 mN. Based on the data collected from the nanoindentation results, the average values of the hardness, Young' modulus and deformation ratio are evaluated, and the fracture toughness is determined to have a value of 3.08 MPa·m〈sup〉½〈/sup〉 at 450 mN. In the Vickers indentation technique, however, by identifying the crack type and choosing the appropriate model, the fracture toughness is calculated to be 1.85–3.44 MPa·m〈sup〉½〈/sup〉 at applied loads ranging from 0.98 to 4.9 N. The obtained fracture toughness results exhibit good consistence between the nanoindentation and Vickers indentation methods.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Y. Le Guével, B. Grégoire, M.J. Cristóbal, X. Feaugas, A. Oudriss, F. Pedraza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrolytic dissolution of aluminide coatings on model (pure Ni, Ni20Cr) and René 125 Ni-based superalloy was conducted by alternated cathodic and anodic polarizations. The pure nickel aluminide dissolved homogeneously. In contrast, the inhomogeneity of dissolution increased with the incorporation of Cr in the coating. The coatings were however uniformly dissolved when the cathodic step was eliminated. XPS and TEM demonstrate that the occurrence of a passive layer containing Cr and Al oxy-hydroxides blocked dissolution.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉(a) TEM bright field images of the passive film of the aluminized Ni20Cr. (b) is a greater magnification showing the distance between the crystalline planes. (c), (d) and (e) are the selected area diffraction patterns of the three diffracted areas defined on (a). The distances marked in red correspond to “d”, i.e. the interplanar distance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897218311976-ga1.jpg" width="343" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Materials Letters, Volume 236〈/p〉 〈p〉Author(s): Jinyan Dai, Jiejie Li, Qunbin Zhang, Min Liao, Tao Duan, Weitang Yao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transition metal chalcogenides as a promising anode material with high theoretical capacity has attracted more and more attention. This thesis focuses on a facile method to synthesize hollow Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 encapsulated by carbon layers (Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@C) with polydopamine as precursor, after reacting with thioacetamide and (NH〈sub〉4〈/sub〉)〈sub〉6〈/sub〉Mo〈sub〉7〈/sub〉O〈sub〉24〈/sub〉·4H〈sub〉2〈/sub〉O, hollow rhombic dodecahedral shape Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉@C@MoS〈sub〉2〈/sub〉 heterostructures are successfully fabricated and employed as the anode of lithium-ion battery. Benefiting from the typical layered structure of Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉@C@MoS〈sub〉2〈/sub〉 heterostructures, the stability and capacity have been significantly improved, with a high capacity of 672.6 mAh g〈sup〉−1〈/sup〉 after 200 cycles at the current density of 0.2 A g〈sup〉−1〈/sup〉. The excellent electrochemical properties of hollow Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉@C@MoS〈sub〉2〈/sub〉 heterostructures are ascribed to the consolidate of Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉, carbon and MoS〈sub〉2〈/sub〉, and the stability of the composite structure.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Structural representation, cycling stability and corresponding Coulombic efficiency of Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉@C@MoS〈sub〉2〈/sub〉 and Co〈sub〉3〈/sub〉S〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 at 0.2 A/g.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0167577X18317464-ga1.jpg" width="432" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Materials Letters, Volume 236〈/p〉 〈p〉Author(s): Deepika Divakaran, Jaya R. Lakkakula, Mukeshchand Thakur, Mukesh Kumar Kumawat, Rohit Srivastava〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biosynthesis of gold nanoparticles from Dragon fruit extract (DF extract) can be considered as an eco-friendly alternative for synthesis of gold nanoparticles. The aim of this study was to investigate the ability of this fruit to synthesize gold nanoparticles and to study its anticancer activity. The as synthesized gold nanoparticles were characterized by UV-vis spectrophotometry, X-ray diffraction, Fourier Transform Infra-red spectroscopy and Transmission Electron microscopy. The results from XRD and TEM support the biosynthesis of DF extract capped gold nanoparticles (DF-AuNPs) in the size range of 10–20 nm. The DF extract and DF-AuNPs induced significant growth inhibition of MCF-7 breast cancer cells however, no significant toxicity effect was observed on MDA-MB-231 cells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0167577X18317361-ga1.jpg" width="321" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Lijia Fang, Jing Huang, Yi Liu, Botao Zhang, Hua Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The booming ocean economy in recent decades crucially demands advanced anti-corrosion technologies for marine infrastructures. Among the marine protective coatings developed in past decades, thermal sprayed aluminium coating was evidenced to be one of the most economical and efficient corrosion protection layers. Yet, marine corrosion is always accompanied by biofouling which in most cases accelerates corrosion. Here we report arc spray fabrication of novel aluminium-copper coatings using home-made Al-Cu cored wires for both anti-corrosion and antifouling performances. Copper particles were dispersed in the as-sprayed coatings, and TEM characterization further revealed partial interaction of Cu particles with Al matrix during the coating deposition. The chemical reaction with the formation of Al〈sub〉2〈/sub〉Cu offered an anchoring effect for the coatings preventing Cu particles from quick releasing into aqueous environment. Electrochemical testing in artificial seawater showed that the presence of Cu in Al coatings did not trigger considerable deterioration in corrosion resistance. Further antifouling testing of the coatings by examining settlement and colonization behaviors of bacteria 〈em〉E. coli〈/em〉 and 〈em〉Bacillus〈/em〉 sp. and typical marine algae revealed their excellent antifouling performances. The antifouling properties were predominately attributed to the continuous release of copper ions from the coatings. The results give clear insight into constructing anti-corrosion/fouling inorganic coatings by the cored-wire arc spray technical route for marine applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Sai Huang, Zhihao Wang, Qi Zhu, Xiaofei Shi, Xuejiao Wang, Xiaodong Li, Xudong Sun, Ji-Guang Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉RE(OH)〈sub〉2.94〈/sub〉(NO〈sub〉3〈/sub〉)〈sub〉0.06〈/sub〉·〈em〉n〈/em〉H〈sub〉2〈/sub〉O nanosquares were first employed as template to synthesize YVO〈sub〉4〈/sub〉:Ln luminescent crystallites (Ln = Eu, Sm, and Dy) via hydrothermal nanoconversion in the presence of NH〈sub〉4〈/sub〉VO〈sub〉3〈/sub〉. Product properties and the course of phase/morphology evolution were characterized in detail by XRD, SEM, TEM, FT-IR, TG, and optical spectroscopy. It was clearly demonstrated that the nanosquares templated vanadate crystallization, owing to structure similarity, but was accompanied by subsequent dissolution and reprecipitation. The resultant vanadate phosphors, mostly in the form of bundles containing platelike and fibrous crystallites, exhibited strong red emission at ∼618 nm for Eu〈sup〉3+〈/sup〉, orange-red emission at ∼604 nm for Sm〈sup〉3+〈/sup〉 and greenish yellow emission at ∼575 nm for Dy〈sup〉3+〈/sup〉 upon exciting the VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 ligand. Dehydration at 500 °C further improved the emission by ∼2.5 times for Eu〈sup〉3+〈/sup〉 and ∼1.5 times for Sm〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉. The Eu〈sup〉3+〈/sup〉 (5 at%), Sm〈sup〉3+〈/sup〉 (1 at%) and Dy〈sup〉3+〈/sup〉 (1 at%) activators were analyzed to have quantum yields of ∼48, 9 and 16% and color coordinates of around (0.65, 0.33), (0.60, 0.39) and (0.38, 0.43) for their luminescence, and fluorescence lifetimes of ∼1.52, 1.40 and 0.89 ms for their dominant emissions, respectively. It is also interesting to find out that replacing only 15% of the total OH〈sup〉−〈/sup〉 and NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 anions in the template by VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 produced ∼20 times stronger Eu〈sup〉3+〈/sup〉 luminescence, indicating that VO〈sub〉4〈/sub〉〈sup〉3-〈/sup〉→ Eu〈sup〉3+〈/sup〉 energy transfer is very efficient. The protocol would be extendable to other types of functional rare-earth compounds.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339719-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Chunmu Guo, Qinghua Tian, Li Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanostructure of titanium dioxide (TiO〈sub〉2〈/sub〉) has gained extensive attention in anode material field of lithium-ion batteries (LIBs) owing to its outstanding structure stability and improved safety over graphite. Herein, facilely controllable synthesis of interestingly spindle TiO〈sub〉2〈/sub〉 nanograins has been achieved by a one-pot hydrothermal and subsequent calcination approach, it is demonstrated that the grain size has a great effect on the electrochemical lithium storage kinetics of as-synthesized TiO〈sub〉2〈/sub〉 nanograins. As a result, the as-prepared TiO〈sub〉2〈/sub〉-0.05M with much smaller size exhibits greatly improved lithium storage performance, delivering a capacity of 120.5 mAh g〈sup〉−1〈/sup〉 after even 1000 cycles.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Xi Cheng, Shi Wei Xu, You Ming Lu, Shun Han, Pei Jiang Cao, Fang Jia, Yu Xiang Zeng, Xin Ke Liu, Wang Ying Xu, Wen Jun Liu, De Liang Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O films with different Cd contents obtained by controlling the growth oxygen pressure (O〈sub〉p〈/sub〉) were deposited on both c-sapphire (Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) substrates and p-GaN substrates, by means of the pulsed laser deposition (PLD) method. Photoluminescence (PL) measurement revealed that the variation of O〈sub〉p〈/sub〉 influenced the amount of Cd doping into Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O films deposited on Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, leading tunable luminescence from the ultraviolet (UV) to blue emission extended to the green band. Then all the fabricated n-Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O/p-GaN heterojunction possessed good ohmic contacts and exhibited typical rectifying characteristic of the diode. Indeed, the high luminescence from the ZnCdO layer could be attained by inserting a MgO insulator to the heterojunction interface. The fabrication of tunable n-Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O/p-GaN heterojunction light-emitting diodes is available which was supported by the results of electroluminescence (EL) experiment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Materials Letters, Volume 236〈/p〉 〈p〉Author(s): K.M. Zhu, S.Y. Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the gas sensing performance of traditional SnO〈sub〉2〈/sub〉 semiconductor nanomaterials, Bi-doped SnO〈sub〉2〈/sub〉 hierarchical flower-shaped nanostructures had been synthesized by a one-step hydrothermal route. Diverse techniques characterization results collectively revealed that Bi ions have been successfully doped into SnO〈sub〉2〈/sub〉 lattice and samples present numerous uniform flower-shaped nanostructures composed of many layered petal-like thin nanosheets. Benefiting from such unique 3D hierarchical flower-shaped nanostructures and Bi doping, the sensors based on Bi-doped SnO〈sub〉2〈/sub〉 exhibited superior gas sensing performance concluding higher response value, faster response/recovery time, good stability and excellent selectivity to HCHO at the optimum operating temperature of 170 °C. Therefore, Bi-doped SnO〈sub〉2〈/sub〉 hierarchical flower-shaped nanostructures could be used as a candidate semiconductor gas sensing materials for manufacturing highly sensitive HCHO gas sensors in the future.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Dina V. Deyneko, Ivan V. Nikiforov, Bogdan I. Lazoryak, Dmitry A. Spassky, Ivan I. Leonidov, Sergey Yu. Stefanovich, Daria A. Petrova, Sergey M. Aksenov, Peter C. Burns〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel red emitting phosphors Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 with whitlockite-type structure were prepared by a high temperature solid-state reaction in air. Powder X-ray diffraction (PXRD), photoluminescence spectra, and fluorescence decay were used to characterize the structure and luminescence properties. All samples were found to have the expected rhombohedral structure with 〈em〉R〈/em〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉3〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉〈em〉c〈/em〉 space group. The non-polar space group is also confirmed by a photoluminescence study. This space group allows forbidden transitions for Eu〈sup〉3+〈/sup〉. The presence of only one Shtark component in 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉0〈/sub〉 confirms the presence of only one non-equivalent site containing Eu〈sup〉3+〈/sup〉 ions. The high intensity of the transition ratio 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉2〈/sub〉/〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉1〈/sub〉 establishes the strongly disordered environment of the Eu〈sup〉3+〈/sup〉 ions. Thus, 〈em〉M〈/em〉1–〈em〉M〈/em〉3 sites in the host matrix are occupied by Ca〈sup〉2+〈/sup〉, Sm〈sup〉3+〈/sup〉, and Eu〈sup〉3+〈/sup〉 ions, whereas 〈em〉M〈/em〉5 is fully occupied by Mg〈sup〉2+〈/sup〉. The optimal concentration was found with 〈em〉x〈/em〉 = 0.75 in Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 phosphors. The emitting of Sm〈sup〉3+〈/sup〉 was depressed due to the high intensity of Eu〈sup〉3+〈/sup〉 luminescence; however, the contribution of Sm〈sup〉3+〈/sup〉 is manifested in the energy transfer process and shift of CIE coordinates. Furthermore, the CIE chromaticity coordinate of 〈em〉as-prepared〈/em〉 Ca〈sub〉8〈/sub〉MgSm〈sub〉0.25〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:0.75Eu〈sup〉3+〈/sup〉 (〈em〉x〈/em〉 = 0.650; 〈em〉y〈/em〉 = 0.345) is close to the standard red-emitting point (〈em〉x〈/em〉 = 0.67, 〈em〉y〈/em〉 = 0.33). The experimental data indicate that Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 upon excitation by near-UV radiation is a promising red phosphor for white-light-emitting diodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339999-fx1.jpg" width="131" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volumes 190–191〈/p〉 〈p〉Author(s): Yufei Yan, Hao Chen, Hongbo Zhang, Changjun Guo, Kai Yang, Kaizhe Chen, Ruoyu Cheng, Niandong Qian, Niklas Sandler, Yu Shrike Zhang, Haokai Shen, Jin Qi, Wenguo Cui, Lianfu Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉3D printed scaffolds hold promising perspective for bone tissue regeneration. Inspired by process of bone development stage, 3D printed scaffolds with rapid internal vascularization ability and robust osteoinduction bioactivity will be an ideal bone substitute for clinical use. Here, we fabricated a 3D printed biodegradable scaffold that can control release deferoxamine, via surface aminolysis and layer-by-layer assembly technique, which is essential for angiogenesis and osteogenesis and match to bone development and reconstruction. Our 〈em〉in vitro〈/em〉 studies show that the scaffold significantly accelerates the vascular pattern formation of human umbilical endothelial cells, boosts the mineralized matrix production, and the expression of osteogenesis-related genes during osteogenic differentiation of mesenchymal stem cells. 〈em〉In vivo〈/em〉 results show that deferoxamine promotes the vascular ingrowth and enhances the bone regeneration at the defect site in a rat large bone defect model. Moreover, this 3D-printed scaffold has excellent biocompatibility that is suitable for mesenchymal stem cells grow and differentiate and possess the appropriate mechanical property that is similar to natural cancellous bone. In summary, this 3D-printed scaffold holds huge potential for clinical translation in the treatment of segmental bone defect, due to its flexibility, economical friendly and practicality.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Biomaterials, Volumes 190–191〈/p〉 〈p〉Author(s): Byung Il Lee, You Jung Chung, Chan Beum Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The abnormal aggregation of β-amyloid (Aβ) peptides is a hallmark of Alzheimer's disease (AD) that affects more than 10% of the people over the age 60 world-wide. While the exact mechanism of neuronal loss and cognitive decline has not been elucidated yet, the amyloid hypothesis about the causative role of Aβ aggregation in AD pathology has been widely supported by the numerous 〈em〉in vivo〈/em〉 and 〈em〉in vitro〈/em〉 data. In this respect, many efforts have been made to explore therapeutic agents that can modulate the aggregation of Aβ, but none of the efforts succeeded in producing effective anti-Aβ drugs for treating AD. This article provides an overview of recent attempts that have employed light energy to intervene with the self-assembly process of Aβ peptides via the generation of oxidative stress by photosensitizers, such as natural or synthetic dyes, light-responsive nanomaterials, and photoelectrochemical platforms. The underlying mechanism of photodynamic reactions suppressing Aβ aggregation and the dilemma in generating long-been-blamed oxidative stress are discussed by addressing the positive role of oxidative stress produced by the photosensitizers in the light-induced suppression of Aβ-mediated neurotoxicity. We have summarized current challenges and strategies to advance photo-induced inhibition and modulation of Aβ aggregation as a therapeutic option for treating AD in the future.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Computer Methods in Applied Mechanics and Engineering, Volume 345〈/p〉 〈p〉Author(s): Hyunsung Choi, Jeong Whan Yoon〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Stress integration algorithm based on finite difference method (FDM) was proposed to effectively deal with both first and second derivatives of yield and potential functions which are the lengthiest component in stress integration procedure. With the proposed numerical algorithm, both first and second derivatives of yield function are approximated by central difference method, so that finite element modeling using advanced constitutive model could be easily performed no matter how complicated its derivatives are. For the verification purpose, the algorithm was applied for advanced constitutive models: Plastic anisotropy model under associated (AFR) and non-associated flow rule (non-AFR), the homogeneous anisotropic hardening (HAH) model under associated (AFR) and non-associated flow rule (non-AFR). The proposed algorithm was verified with single element loading–unloading and cup-drawing simulations. The Euler backward method based on both the proposed numerical algorithm and analytical derivatives were employed for verification purpose. The accuracy and time efficiency of the proposed numerical algorithm were evaluated by comparing the simulation results from analytical derivatives. In addition, the applicability of the proposed numerical algorithm for the HAH models was estimated with single element loading–unloading, loading–reloading, and deep-drawing/springback simulations. Non-associated flow plasticity for the HAH model is newly proposed to improve numerical efficiency with finite difference method by keeping the same level of accuracy as associated flow rule plasticity. All the simulation results proved that the proposed numerical algorithm can be widely used for the implementation of advanced constitutive models.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Wanwu Ding, Chen Xu, Xingang Hou, Xiaoyan Zhao, Taili Chen, Wenjun Zhao, Tiandong Xia, Jisen Qiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The new type of Al-Ti-C-La master alloy was prepared by commercial pure Al, Ti powder, graphite powder, Al powder and La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 powder by aluminum melt in-situ reaction method. The microstructure and the effect on commercial pure aluminum of Al-Ti-C-La master alloy have been studied by means of X-ray diffraction (XDR), scanning electron microscopy (SEM) equipped with energy-dispersive spectrometry (EDS). The synthesis thermodynamics and kinetics of Al-Ti-C-La master alloy were analyzed. The experiment shows that Al-Ti-C-La master alloy is composed of Al, Al〈sub〉3〈/sub〉Ti, TiC and Ti〈sub〉2〈/sub〉Al〈sub〉20〈/sub〉La. The refining performance of the prepared Al-Ti-C-La master alloy is obviously better than that of Al-Ti-C master alloy when the addition of rare earth oxide La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is 10 wt% and the preparation temperature is 930 °C. The analysis of thermodynamic calculation and the process of kinetics demonstrate that, in the preparation process of Al-Ti-C-La master alloy, firstly, Al reacts with Ti to produce Al〈sub〉3〈/sub〉Ti, C reacts with Ti and Al〈sub〉3〈/sub〉Ti to form TiC based on the aluminothermy reaction. Rare earth oxide La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and C powder react with Ti powder and O〈sub〉2〈/sub〉 in the air occur to generate CO, TiC, [La] atoms and LaC〈sub〉2〈/sub〉. [La] atoms adsorb on the surface of Al〈sub〉3〈/sub〉Ti to form the new rare earth compounds Ti〈sub〉2〈/sub〉Al〈sub〉20〈/sub〉La.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Changmeng Huan, Xinyue Zhao, Xiudi Xiao, Yuan Lu, Shuai Qi, Yongjun Zhan, Lingzhi Zhang, Gang Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles (NPs) with ultrathin carbon shells were synthesized by a facile solvothermal process. The V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NPs were about 30 nm and contained a carbon shell of about 2 nm thick. The V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NPs were homogeneously dispersed and loosely packed. When used as anode material, the V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 core-shell NPs showed a reversible capacity up to 525 mA h g〈sup〉−1〈/sup〉 at 200 mA g〈sup〉−1〈/sup〉 over 200 cycles with good cycle stability and rate capability. The excellent electrochemical performance promotes its practical application in lithium-ion batteries.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Honghong Jin, Guang Sun, Bo Zhang, Na Luo, Yanwei Li, Long Lin, Hari Bala, Jianliang Cao, Zhanying Zhang, Yan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel chain-like nanostructure of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 was successfully prepared via a facile and reliable oxalate sacrificial template route, in which coralloid cobalt oxalate (CoC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O) precursor was first obtained through a room-temperature precipitation method and then used as sacrificial template to prepare Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 by annealing at 500 °C. Au nanoparticles-decorated Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains were also prepared by soaking the CoC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 precursor in Au〈sup〉+〈/sup〉 solution before the annealing process. The prepared samples were characterized by XRD, FESEM, TEM, and N〈sub〉2〈/sub〉 adsorption-desorption. Results indicated that the pure and Au-decorated Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains were constructed by several end-to-end connected nanoparticles, and their specific surface areas were 28.42 m〈sup〉2〈/sup〉/g and 37.39 m〈sup〉2〈/sup〉/g, respectively. The gas sensing properties of the prepared samples were tested and compared. It was found that after being functionalized with Au nanoparticles, the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains showed an improved TEA sensing performance, such as lower optimal working temperature, higher response, and faster response and recover speed. In addition, the Au/Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 sensor can also give a good linearity in the TEA concentration range from 10 to 200 ppm and considerable stability within 7 weeks, suggesting its potential application for quantitative detection of TEA. The improved gas sensing mechanism of the Au/Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochain was discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): V.A. Lysenko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A modified version of the Sb-Sn phase diagram was proposed that includes both Sb〈sub〉2〈/sub〉Sn〈sub〉3〈/sub〉 and Sb〈sub〉3〈/sub〉Sn〈sub〉4〈/sub〉 compounds. Based on this modification, phase equilibria in the In-Sb-Sn system were calculated using a thermodynamic modeling approach. Thermodynamic models for the ternary liquid phase and solid solutions (SbSn) and (Sb〈sub〉2〈/sub〉Sn〈sub〉3〈/sub〉) were developed. The isopleths 〈em〉x〈/em〉〈sub〉Sn〈/sub〉 = 0.2, 0.5, 0.8, vertical sections 〈em〉x〈/em〉〈sub〉In〈/sub〉/〈em〉x〈/em〉〈sub〉Sb〈/sub〉 = 3:1, 1:1, 1:3, liquidus surface projection, and isothermal section at 473 K were calculated.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Hongyi Gao, Mengyi Jia, Keyi Dong, Liwen Xing, Xiao Chen, Dandan Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Sisal-Like TiO〈sub〉2〈/sub〉/Graphene-Like Carbon Sheets (SL-TiO〈sub〉2〈/sub〉/GLCSs) composite was fabricated via a facile one-pot self-assembling route at a two-phase interface. The ingenious P123 was introduced to serve a dual function of carbon precursor and structure-directing agent, which first assembled at the water/oil interfaces and subsequently was in situ carbonized to GLCSs. Then the sisal-like TiO〈sub〉2〈/sub〉 grew gradually on the GLCSs along the preferred direction. This process shows several advantages such as simple processes, mild condition, low cost and good combination of SL-TiO〈sub〉2〈/sub〉 and GLCSs. The combination of SL-TiO〈sub〉2〈/sub〉 with GLCSs significantly helps the adsorption of substrates as well as promotes electron-hole pair separation, exhibiting good photocatalytic activity towards degradation of methylene blue (MB) compared to the pristine SL-TiO〈sub〉2〈/sub〉 and commercial P25. This strategy opens up new perspectives for fabricating novel composites of nanooxides/GLCSs.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Zhennan Liu, Naiqin Zhao, Chunsheng Shi, Fang He, Enzuo Liu, Chunnian He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three-dimensional (3D) carbon networks decorated with Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles as lightweight and broadband electromagnetic (EM) wave absorber were 〈em〉in-situ〈/em〉 prepared via a simple and large-scale method, combining freeze-drying and high-temperature calcination processes. SEM and TEM results show that 3D carbon network/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 (3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉) composites have interconnected 3D porous carbon networks with submicrometer-sized macropores, and the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles are distributed uniformly on the 3D carbon networks. The EM wave absorption performance of 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 can be tuned by changing Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 contents. The 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 with about 38.2 wt% Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 exhibits excellent lightweight and broadband EM wave absorption property. The effective absorption bandwidth can reach up 5.95 GHz (11.2–17.15 GHz) at the thickness of 3.0 mm with only 20 wt% filler loading. The minimum RL of −37.8 dB was obtained at 6.95 GHz. The excellent EM wave absorption capability of 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 can be ascribed to good impedance matching, strong dielectric loss ability and unique 3D porous structure. This work demonstrates that the 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 with light weight, broad absorption bandwidth and large-scale production potential can be a promising absorber for practical application.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339768-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉