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A new polymorph of iodic acid, δ-HIO3, synthesized via aerosol spray pyrolysis was characterized with powder X-ray diffraction and its crystal structure was solved. We find that a previously misidentified phase of I4O9 hydrate is in fact a new polymorph of HIO3, which crystalizes in the orthorhombic space group P212121.
The codeposition characteristics of Si–B–N ceramics from the SiCl4–NH3–BCl3–H2–Ar system at lower temperatures and phase transformation of as-prepared Si–B–N ceramics at temperatures from 1200 to 1800 °C were investigated. Thermodynamic analysis results indicated that the BN + Si3N4 dual phase region existed from 800 to 1200 °C and that 800 °C was an optimum deposition temperature to deposit Si–B–N ceramic coating. Deposition efficiencies at equilibrium for Si3N4 and BN were high, particularly at temperatures below 1000 °C. Pressure and dilution ratio of H2 had little influence on deposition efficiencies of BN and Si3N4 at 800 °C. The amorphous Si–B–N ceramic coatings were successfully deposited at 800 °C from the same precursor system and contained N–B and N–Si bonds by XPS analysis. It kept amorphous below 1600 °C in N2 and partly transformed to α/β-Si3N4 when heat treated at 1600 °C in N2 for 2 h. These results demonstrated that the composite Si–B–N ceramics could be fabricated at 800 °C and used below 1600 °C.
Mesoscale heterogeneous material systems are efficient and adaptive to real world environments, owing to the non-uniform stress fields that result from the convolution of component geometries, loading conditions, and environmental changes. With the advent of multi-material additive manufacturing, the production of heterogeneous material systems with a pre-defined mesoscale material distribution becomes feasible. This unlocks the design freedom at a characteristic length scale between the macroscale geometry and microstructures, but also calls for a new design framework to optimize the mesoscale material distribution in multi-material additive manufacturing. Here, we propose and demonstrate such a design framework by incorporating digital image correlation-based deformation mapping with 3D finite element modeling-based computational optimization. The constitutive behavior of each constituent material or their mixtures is calibrated by matching the local deformation data. The optimal mesoscale material distribution can then be determined using global optimization algorithms and validated experimentally.
A new waterborne acrylic (WAC) hybrid adhesive was evaluated for an untreated polypropylene lamination. The WAC hybrid adhesive was formulated with a new class of porous clay heterostructure (PCH), which was modified with 3-(trimethoxysilyl)propyl methacrylate (as a coupling agent) to promote chemical bonding with the acrylic matrix to form a methacrylate-functionalized PCH (MPCH). The WAC hybrid adhesive was based on copolymers (2-ethylhexyl acrylate, ethylene glycol methyl ether acrylate, 2-(hydroxyethyl) methacrylate, styrene and acrylic acid) with varying amounts of MPCH. The scanning electron microscopy micrographs revealed the presence of a well dispersed MPCH distributed throughout the matrix. The optimal adhesive performance, in terms of the 180° peel strength of bonded joints, of 140.2 N/m was achieved using 1.5 wt% of MPCH, while the thermal stability of the adhesives was improved with increasing MPCH loading levels.
Electrochemical sensing systems are advancing into a wide range of new applications, moving from the traditional lab environment into disposable devices and systems, enabling real-time continuous monitoring of complex media. This transition presents numerous challenges ranging from issues such as sensitivity and dynamic range, to autocalibration and antifouling, to enabling multiparameter analyte and biomarker detection from an array of nanosensors within a miniaturized form factor. New materials are required not only to address these challenges, but also to facilitate new manufacturing processes for integrated electrochemical systems. This paper examines the recent advances in the instrumentation, sensor architectures, and sensor materials in the context of developing the next generation of nanoenabled electrochemical sensors for life sciences applications, and identifies the most promising solutions based on selected well established application exemplars.
Mg–3.0Y–2.5Nd–1.0Gd–xZn–0.5Zr (x = 0, 0.2, 0.5, and 1.0) (wt%) alloys were produced by metallic and sand mold casting to study the microstructure and mechanical properties of the alloys. The as-cast Zn-free alloys consist of α-Mg and eutectics, whereas the Zn-containing alloys contain additional long-period stacking ordered (LPSO) structures. With a higher solidification, the cooling rate brought by metallic mold casting, grains, and eutectics are refined, which enhances the elongation of the alloys, accompanied by a decrease of area fraction of the LPSO structure. Some residual eutectics in the Mg–3.0Y–2.5Nd–1.0Gd–1.0Zn–0.5Zr alloys act as obstacles to grain boundary migration during solution treatment, which make the average grain size 15–20 μm smaller than that of the other alloys and hence improve the elongation of the alloys. The Zn addition brings notable enhancements to mechanical properties of the alloys due to solid solution strengthening of Zn. Especially, the peak-aged Mg–3.0Y–2.5Nd–1.0Gd–0.5Zn–0.5Zr alloys perform with the highest overall tensile properties.
We used density functional theory to investigate the electrochemical CO2 reduction and competing hydrogen evolution reaction on model Au, Ag, Cu, Ir, Ni, Pd, Pt, and Rh nanoparticles. On the coinage metal, the free energy of adsorbed COOH, CO, and H intermediates generally becomes more favorable with decreasing particle size. This pattern was also observed on all transition metals with the binding of the intermediates observed to be stronger on almost all of these metals. Comparative studies of the reaction profile reveal that H2 evolution is the first reaction to be energetically allowed at zero applied bias.
Doping is a potent and often used strategy to modify properties of active electrode materials in advanced electrochemical batteries. There are several factors by which doping changes properties critically affecting battery performance, most notably the voltage, capacity, rate capability, and stability. These factors have to do specifically with changes in structure, band gap and band structure, and structural instability induced by doping. We review our recent modeling works on the effects of doping of active electrode materials, notably for prospective materials for organic and post-lithium (Na ion, Mg ion) batteries, as well as present new results, to build a coherent view on the use of n- and p-doping to modulate Li, Na, and Mg storage properties, most notably voltage. Specifically, we clearly point out effects due to electronic structure and those due to strain (structural instability), which clears some confusion about the effects of n- versus p-doping and facilitates rational rather than ad hoc design of doped materials.
The practical realization of energy-efficient computing vectors is imperative to address the break-down in the scaling of power consumption with transistor dimensions, which has led to substantial underutilized chip space. Memristive elements that encode information in multiple internal states and reflect the dynamical evolution of these states are a promising alternative. Herein we report the observation of pinched loop hysteretic type-II memristive behavior in single-crystalline nanowires of a versatile class of layered vanadium oxide bronzes with the composition δ-[M(H2O)4]0.25V2O5 (M = Co, Ni, Zn), the origin of which is thought to be the diffusion of protons in the interlayer regions.
In this paper, we report on the microstructural evolution and mechanical properties of a 5052 Al alloy processed by rotationally accelerated shot peening (RASP). A thick deformation layer of ∼2 mm was formed after the RASP process. Nano-sized grains, equiaxed subgrains, and elongated subgrains were observed along the depth of the deformation layer. Dislocation accumulation and dynamic recrystallization were found primarily responsible for the grain refinement process. An obvious microhardness gradient was observed for all of the samples with different RASP processing parameters, and the microhardness in the top surface of 50 m/s-5 min RASP-processed sample is twice that of its coarse-grained (CG) counterpart. The yield strengths of the RASP-processed 5052 Al alloy samples were 1.4–2.6 times that of CG counterparts, while retaining a decent ductility (25–84% that of CG). The superior properties imparted by the gradient structure are expected to expand the application of the 5052 Al alloy as a structural material.
A new plasmonic photocatalyst Ag/Bi7Ta3O18 was fabricated by photodeposition-hydrothermal method. The phase composition, microstructure, surface areas, average pore size, UV-vis diffuse reflection spectra, and photocatalytic activities of composite photocatalysts were investigated in detail. The results of the measurements indicated that the Ag0 nanoparticle successfully loads on the surface of Bi7Ta3O18, and the 0.06 Ag/Bi7Ta3O18 photocatalysts exhibited the best photocatalytic activity for the degradation of Rhodamine B (RhB). The improved photocatalytic activity could be contributed to the localized surface plasmon resonance caused by the collective oscillation of the surface electrons of Ag nanoparticles. Additionally, the photocatalytic reaction mechanism was studied by photoluminescence photocurrent, and electron spin resonance analysis. As a result, the Ag nanoparticles onto the Bi7Ta3O18 surface enlarged the electron–hole separation, and the (˙OH) was the dominated active species of degradation RhB in the photocatalytic process.
Human organoid models recapitulate many aspects of the complex composition and function of native organs. One of the main challenges in developing these models is the growth and maintenance of three-dimensional tissue structures and proper cellular organization that enable function. Biomaterials play an important role by providing a defined and tunable three-dimensional environment that is required for complex cellular organization and organoid growth in vitro or in vivo. This review summarizes organoids of the respiratory and digestive system, and the use of biomaterials to improve upon these model systems.
U60 ([UO2(O2)(OH)]6060− in water) is a uranyl peroxide nanocluster with a fullerene topology and Oh symmetry. U60 clusters can exist in crystalline solids or in liquids; however, little is known of their behavior at high pressures. We compressed the U60-bearing material: Li68K12(OH)20[UO2(O2)(OH)]60(H2O)310 ($Fm\bar 3$; a = 37.884 Å) in a diamond anvil cell to determine its response to increasing pressure. Three length scales and corresponding structural features contribute to the compression response: uranyl peroxide bonds (<0.5 nm), isolated single nanoclusters (2.5 nm), and the long-range periodicity of nanoclusters within the solid (>3.7 nm). Li68K12(OH)20[UO2(O2)(OH)]60(H2O)310 transformed to a tetragonal structure below 2 GPa and irreversibly amorphized between 9.6 and 13 GPa. The bulk modulus of the tetragonal U60-bearing material was 25 ± 2 GPa. The pressure-induced amorphous phase contained intact U60 clusters, which were preserved beyond the loss of long-range periodicity. The persistence of U60 clusters at high pressure may have been enhanced by the interaction between U60 nanoclusters and the alcohol pressure medium. Once formed, U60 nanoclusters persist regardless of their associated long-range ordering—in crystals, amorphous solids, or solutions.
The tunnel field-effect transistor (TFET) is one of the candidates replacing conventional metal–oxide–semiconductor field-effect transistors to realize low-power-consumption large-scale integration (LSI). The most significant issue in the practical application of TFETs concerns their low tunneling current. Si is an indirect-gap material having a low band-to-band tunneling probability and is not favored for the channel. However, a new technology to enhance tunneling current in Si-TFETs utilizing the isoelectronic trap (IET) technology was recently proposed. IET technology provides a new approach to realize low-power-consumption LSIs with TFETs. The present paper reviews the state-of-the-art research and future prospects of Si-TFETs with IET technology.