ALBERT

Description: We grew a series of co-doped LiNbO3 crystals with fixed 1.5 mol % ZrO2 and various MgO concentrations (1.0, 3.0, 4.0, 6.0 mol %), and investigated their optical properties and defect structures. By 3.0 mol % MgO co-doping, the optical damage resistance at 532 nm reached 6.5 × 106 W/cm2, while the phase-matching temperature for doubling 1064 nm was only 29.3 °C—close to room temperature—which was conducive to realizing the 90° phase matching at room temperature by slightly modulating the incident angle of the fundamental beam. Notably, we found that the phase-matching temperature increased linearly with the increase of MgO doping, and this linear dependence helped us to grow the high-quality crystal for room temperature 90° phase matching. Moreover, the defect analysis indicated that the linear tuning of phase-matching temperature might be attributed to Mg Li + + Zr Nb − neutral pairs in crystals.

Description: Nature has inspired the fabrication of intelligent devices to meet the needs of the advanced community and better understand the imitation of biology. As a biomimetic nanodevice, nanochannels/nanopores aroused increasing interest because of their potential applications in nanofluidic fields. In this review, we have summarized some recent results mainly focused on the design and fabrication of one-dimensional nanochannels, which can be made of many materials, including polymers, inorganics, biotic materials, and composite materials. These nanochannels have some properties similar to biological channels, such as selectivity, voltage-dependent current fluctuations, ionic rectification current and ionic gating, etc. Therefore, they show great potential for the fields of biosensing, filtration, and energy conversions. These advances can not only help people to understand the living processes in nature, but also inspire scientists to develop novel nanodevices with better performance for mankind.

Description: Corneal diseases constitute the second leading cause of vision loss and affect more than 10 million people globally. As there is a severe shortage of fresh donated corneas and an unknown risk of immune rejection with traditional heterografts, it is very important and urgent to construct a corneal equivalent to replace pathologic corneal tissue. Corneal tissue engineering has emerged as a practical strategy to develop corneal tissue substitutes, and the design of a scaffold with mechanical properties and transparency similar to that of natural cornea is paramount for the regeneration of corneal tissues. Nanofibrous scaffolds produced by electrospinning have high surface area–to-volume ratios and porosity that simulate the structure of protein fibers in native extra cellular matrix (ECM). The versatilities of electrospinning of polymer components, fiber structures, and functionalization have made the fabrication of nanofibrous scaffolds with suitable mechanical strength, transparency and biological properties for corneal tissue engineering feasible. In this paper, we review the recent developments of electrospun scaffolds for engineering corneal tissues, mainly including electrospun materials (single and blended polymers), fiber structures (isotropic or anisotropic), functionalization (improved mechanical properties and transparency), applications (corneal cell survival, maintenance of phenotype and formation of corneal tissue) and future development perspectives.

Description: A series of heavily Fe-doped LiNbO3 (LN:Fe) crystals were grown via the Czochralski method. The dark- and photo-conductivity of the 5.0 wt.% Fe-doped LiNbO3 crystal reached 3.30 × 10−8 Ω−1 cm−1 and 1.46 × 10−7 Ω−1 cm−1 at 473 nm, which are about 7 and 5 orders of magnitude higher than that of congruent LiNbO3, respectively. Then, a p-n heterojunction was fabricated by depositing the heavily Fe-doped LiNbO3 on a p-type Si substrate using the pulsed laser deposition. The current–voltage curve of the LN:Fe/Si heterojunction presents a well-defined behavior with a turn-on voltage of 2.9 V. This LN:Fe/Si heterojunction gives an excellent prototype device for integrated optics and electro-photonics.

Description: Numerous studies have indicated that intrinsic defects in lithium niobate (LN) dominate its physical properties. In an Nb-rich environment, the structure that consists of a niobium anti-site with four lithium vacancies is considered the most stable structure. Based on the density functional theory (DFT), the specific configuration of the four lithium vacancies of LN were explored. The results indicated the most stable structure consisted of two lithium vacancies as the first neighbors and the other two as the second nearest neighbors of Nb anti-site in pure LN, and a similar stable structure was found in the doped LN. We found that the defects dipole moment has no direct contribution to the crystal polarization. Spontaneous polarization is more likely due to the lattice distortion of the crystal. This was verified in the defects structure of Mg2+, Sc3+, and Zr4+ doped LN. The conclusion provides a new understanding about the relationship between defect clusters and crystal polarization.

Description: Nitrogen-doped lithium niobate (LiNbO3:N) thin films were successfully fabricated on a Si-substrate using a nitrogen plasma beam supplied through a radio-frequency plasma apparatus as a dopant source via a pulsed laser deposition (PLD). The films were then characterized using X-Ray Diffraction (XRD) as polycrystalline with the predominant orientations of (012) and (104). The perfect surface appearance of the film was investigated by atomic force microscopy and Hall-effect measurements revealed a rare p-type conductivity in the LiNbO3:N thin film. The hole concentration was 7.31 × 1015 cm−3 with a field-effect mobility of 266 cm2V−1s−1. X-ray Photoelectron Spectroscopy (XPS) indicated that the atom content of nitrogen was 0.87%; N atoms were probably substituted for O sites, which contributed to the p-type conductivity. The realization of p-type LiNbO3:N thin films grown on the Si substrate lead to improvements in the manufacturing of novel optoelectronic devices.

Description: Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V4+ and Fe3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48.

Description: Surface-enhanced Raman scattering (SERS) has demonstrated single-molecule sensitivity and is becoming intensively investigated due to its significant potential in chemical and biomedical applications. SERS sensing is highly dependent on the substrate, where excitation of the localized surface plasmons (LSPs) enhances the Raman scattering signals of proximate analyte molecules. This paper reviews research progress of SERS substrates based on both plasmonic materials and nano-photonic structures. We first discuss basic plasmonic materials, such as metallic nanoparticles and nano-rods prepared by conventional bottom-up chemical synthesis processes. Then, we review rationally-designed plasmonic nano-structures created by top-down approaches or fine-controlled synthesis with high-density hot-spots to provide large SERS enhancement factors (EFs). Finally, we discuss the research progress of hybrid SERS substrates through the integration of plasmonic nano-structures with other nano-photonic devices, such as photonic crystals, bio-enabled nanomaterials, guided-wave systems, micro-fluidics and graphene.

Description: This study is focused on the preparation and performance of a building energy storage panel (BESP). The BESP was fabricated through a mold pressing method based on phase change material particle (PCMP), which was prepared in two steps: vacuum absorption and surface film coating. Firstly, phase change material (PCM) was incorporated into expanded perlite (EP) through a vacuum absorption method to obtain composite PCM; secondly, the composite PCM was immersed into the mixture of colloidal silica and organic acrylate, and then it was taken out and dried naturally. A series of experiments, including differential scanning calorimeter (DSC), scanning electron microscope (SEM), best matching test, and durability test, have been conducted to characterize and analyze the thermophysical property and reliability of PCMP. Additionally, the thermal performance of BESP was studied through a dynamic thermal property test. The results have showed that: (1) the surface film coating procedure can effectively solve the leakage problem of composite phase change material prepared by vacuum impregnation; (2) the optimum adsorption ratio for paraffin and EP was 52.5:47.5 in mass fraction, and the PCMP has good thermal properties, stability, and durability; and (3) in the process of dynamic thermal performance test, BESP have low temperature variation, significant temperature lagging, and large heat storage ability, which indicated the potential of BESP in the application of building energy efficiency.

Description: Concrete production utilizes cement as its major ingredient. Cement production is an important consumer of natural resources and energy. Furthermore, the cement industry is a significant CO2 producer. To reduce the environmental impact of concrete production, supplementary cementitious materials such as fly ash, blast furnace slag, and silica fume are commonly used as (partial) cement replacement materials. However, these materials are industrial by-products and their availability is expected to decrease in the future due to, e.g., closing of coal power plants. In addition, these materials are not available everywhere, for example, in developing countries. In these countries, industrial and agricultural wastes with pozzolanic behavior offer opportunities for use in concrete production. This paper summarizes the engineering properties of concrete produced using widespread agricultural wastes such as palm oil fuel ash, rice husk ash, sugarcane bagasse ash, and bamboo leaf ash. Research on cement replacement containing agricultural wastes has shown that there is great potential for their utilization as partial replacement for cement and aggregates in concrete production. When properly designed, concretes containing these wastes have similar or slightly better mechanical and durability properties compared to ordinary Portland cement (OPC) concrete. Thus, successful use of these wastes in concrete offers novel sustainable materials and contributes to greener construction as it reduces the amount of waste, while also minimizing the use of virgin raw materials for cement production. This paper will help the concrete industry choose relevant waste products and their optimum content for concrete production. Furthermore, this study identifies research gaps which may help researchers in further studying concrete based on agricultural waste materials.