PMMA/β-TCP composites were evaluated to be suitable for laser sintering earlier, but the possible after effects are not known yet. Effects of sintering on the biological nature and the influences of critical compositions and process parameters have not been investigated so far. The current research attempts this, first identifying experimentally the most suitable laser process conditions for the specific grades of PMMA and β-TCP and then subjecting single layer sintered samples to FTIR analysis and in vitro studies involving MTT and ALP assays, alizarin red S tests, and real-time PCR analyses. While the laser interactions are not detrimental, the biological responses are generally positive proving the selective laser sintering of PMMA/β-TCP composites to be a potential approach for specific medical applications.

In this work, activated carbon was modified by ammonium persulfate and used as the catalyst support for CO2 hydrogenation to methanol. Then CuO and/or ZnO were loaded on the support by a facile wet-impregnation method. The obtained CuZn/C, Cu/C, and Zn/C catalysts were characterized by a series of characterization techniques including N2 physisorption, X-ray diffraction (XRD), X-ray photoelectron (XPS), and scanning and transmission electron microscopies (SEM and TEM). XRD and XPS results showed that ZnO affected the reduction of Cu2+. The TEM results showed that Cu particles were 14–18 nm for the fresh catalysts CuZn/C and Cu/C. ZnO particles were too small to be identified by TEM. The used catalysts CuZn/C and Cu/C had particle sizes of 10–25 nm and 50–60 nm, respectively. The enhanced methanol synthesis performance by ZnO could be ascribed to the morphology effect and slowing down the Cu particles sintering during the reactions.

The microstructure evolution of high nitrogen austenitic steel wires under various annealing times and drawing temperatures was carefully characterized. Special attention was paid to the widely distributed twins and the nanoprecipitates at twin boundaries (TBs) in high nitrogen stainless steels (HNSSs). The results of microhardness indicated that the traditional Hall–Petch (H–P) equation, which only took the role of grain boundaries into account, was unsuitable. A new H–P equation that connected grain size, twin density, precipitates at TBs, and microhardness in HNSS was established for the first time and showed to be in good agreement with the experimental results. By analyzing the strained regions near TBs, a model describing the precipitation of nano-M23C6 carbides on coherent twin boundaries and incoherent twin boundaries was proposed. In addition, the influence mechanism of the nano-M23C6 at TBs on microhardness was discussed.

Functionally graded materials (FGMs) in which the elemental composition intentionally varies with position can be fabricated using directed energy deposition additive manufacturing (AM). This work examines an FGM that is linearly graded from V to Invar 36 (64 wt% Fe, 36 wt% Ni). This FGM cracked during fabrication, indicating the formation of detrimental phases. The microstructure, composition, phases, and microhardness of the gradient zone were analyzed experimentally. The phase composition as a function of chemistry was predicted through thermodynamic calculations. It was determined that a significant amount of the intermetallic σ-FeV phase formed within the gradient zone. When the σ phase constituted the majority phase, catastrophic cracking occurred. The approach presented illustrates the suitability of using equilibrium thermodynamic calculations for the prediction of phase formation in FGMs made by AM despite the nonequilibrium conditions in AM, providing a route for the computationally informed design of FGMs.

3D printing has been shown to be a robust and inexpensive manufacturing tool for a range of applications within biomedical science. Here we report the design and fabrication of a 3D printer-enabled microfluidic device used to generate cell-laden hydrogel microspheres of tunable sizes. An inverse mold was printed using a 3D printer, and replica molding was used to fabricate a PDMS microfluidic device. Intersecting channel geometry was used to generate perfluorodecalin oil-coated gelatin methacrylate (GelMA) microspheres of varying sizes (35–250 μm diameters). Process parameters such as viscosity profile and UV cross-linking times were determined for a range of GelMA concentrations (7–15% w/v). Empirical relationships between flow rates of GelMA and oil phases, microspheres size, and associated swelling properties were determined. For cell experiments, GelMA was mixed with human osteosarcoma Saos-2 cells, to generate cell-laden GelMA microspheres with high long-term viability. This simple, inexpensive method does not require the use of traditional cleanroom facilities and when combined with the appropriate flow setup is robust enough to yield tunable cell-laden hydrogel microspheres for potential tissue engineering applications.

The three-dimensional microstructures of two conventional 316L stainless steels and a grain boundary (GB)-engineered version of the same steel have been characterized by using serial sectioning and electron backscatter diffraction mapping. The morphologies, area fractions, and number fractions of twin boundaries (TBs) were measured and compared, and the random boundary connectivity was evaluated. Although two-dimensional observations suggest that TBs are planar, occluded twin-grains and tunnel-shaped TBs were also observed. In addition, some large and morphologically complex TBs were observed in the GB-engineered sample, and these TBs were responsible for the increase in the twin area fraction that has been reported in past studies. While GB engineering increased the boundary area fraction, the TB number fraction was almost unchanged. Because the GB engineering process changed only the area fraction and not the number fraction, the connectivity of random boundaries was not disrupted.

As a new functional composite material, functionally graded shape memory alloy (FG-SMA) holds particular properties of both functionally graded materials and shape memory alloys. By bringing in a new concept of conical surface assumption, considering the axial deformation, a macroconstitutive model which can describe the thermal mechanical properties of a FG-SMA cylinder subjected to pressure and graded temperature loads is established in this work. Furthermore, a new layered finite element model (FEM) which can avoid the direct assumption of the macroproperties of the FG-SMA cylinder is provided. The theoretical results display a good agreement with the FEM results, which indicates that both the macroconstitutive model and the FEM provided here are valid. The obtained results show that the stress in the cylinder distributes complexly, and it decreases remarkably as a result of the martensite transformation. This research can provide a base for the design and in-depth investigation of FG-SMA materials.

A great challenge in the field of neurocomputing is to mimic the brain behavior by implementing artificial synapses and neurons directly in hardware. This work shows that a Leaky Integrate and Fire (LIF) artificial neuron can be realized with a two-terminal device made of Mott insulator thin films. Polycrystalline thin films of the well-known Mott insulator oxide (V0.95Cr0.05)2O3 were deposited by magnetron sputtering and patterned with micron-scale TiN electrodes. These devices exhibit a volatile resistive switching and a remarkable LIF behavior under a train of pulses suggesting that LIF artificial neurons may be realized from (V0.95Cr0.05)2O3 thin films.

Significant reductions recently seen in the size of wide-bandgap power electronics have not been accompanied by a relative decrease in the size of the corresponding magnetic components. To achieve this, a new generation of materials with high magnetic saturation and permeability are needed. Here, we develop gram-scale syntheses of superparamagnetic Fe/FexOy core–shell nanoparticles and incorporate them as the magnetic component in a strongly magnetic nanocomposite. Nanocomposites are typically formed by the organization of nanoparticles within a polymeric matrix. However, this approach can lead to high organic fractions and phase separation; reducing the performance of the resulting material. Here, we form aminated nanoparticles that are then cross-linked using epoxy chemistry. The result is a magnetic nanoparticle component that is covalently linked and well separated. By using this ‘matrix-free’ approach, we can substantially increase the magnetic nanoparticle fraction, while still maintaining good separation, leading to a superparamagnetic nanocomposite with strong magnetic properties.

To prepare high quality large solidified Al2O3/ZrO2 eutectic ceramic, the preparation processing of the presintered ceramic as a feed rod was investigated via experiments; some parameters of the induction heating zone process were optimized via numerical modeling; an Al2O3/ZrO2 eutectic ceramic rod with a diameter 10 mm was prepared. The results show that increasing the sintering temperature could increase the presintered ceramic’s bulk density, while increasing sintering time had little effect. And the bulk density increased first and then decreased with the molding pressure increase. And the saucer coil obtained a higher temperature gradient than the tubbiness coil for a fixed crucible wall maximum temperature, and the coil turn’s increase could increase the melting zone height in the induction zone melting process. In the directionally solidified Al2O3/ZrO2 eutectic ceramics, Al2O3 phase is the matrix phase, and the ZrO2 phase embedded in the Al2O3 phase mostly with the rod shape, and little with lamellar. The hardness of directionally solidified eutectic ceramics reaches 16.17 GPa and the fracture toughness reaches 4.76 MPa m1/2, which are 1.7 times and 1.5 times of the presintered eutectic ceramic, respectively.

This work aims at providing guidance through systematic experimental characterization for the design of 3D-printed scaffolds for potential orthopedic applications, focusing on fused deposition modeling with a composite of clinically available polycaprolactone (PCL) and β-tricalcium phosphate (β-TCP). First, we studied the effect of the chemical composition (0–60% β-TCP/PCL) on the scaffold’s properties. We showed that surface roughness and contact angle were, respectively, proportional and inversely proportional to the amount of β-TCP and that degradation rate increased with the amount of ceramic. Biologically, the addition of β-TCP enhanced proliferation and osteogenic differentiation of C3H10. Second, we systematically investigated the effect of the composition and the porosity on the 3D-printed scaffold mechanical properties. Both an increasing amount of β-TCP and a decreasing porosity augmented the apparent Young’s modulus of the 3D-printed scaffolds. Third, as a proof of concept, a novel multimaterial biomimetic implant was designed and fabricated for potential disc replacement.

AZ91 magnesium plates with a thickness of 6 mm were subjected to one- and two-pass friction stir processing (FSP). Microstructures and mechanical properties of the experimental materials were investigated. The results show that FSP can significantly refine the microstructures of magnesium alloys, and two-pass FSP can prepare slightly finer grains in comparison with one-pass FSP. Some coarse β-Mg17Al12 phases existed in the first pass FSP break and dissolve into the matrix under the action of the second pass FSP. Microhardness distribution of the two-pass FSP AZ91 alloy exhibits no too much difference with that of the one-pass FSP AZ91 alloy. Due to further finer microstructures, the tensile properties of the two-pass FSP alloy are slightly higher than those of the one-pass FSP alloy. Both FSP AZ91 alloys show typical ductile fracture characteristics, while the dimples on the two-pass FSP specimen are much deeper and increase in quantity.

The effect of aging time on the corrosion behavior of 6005 Al alloys has been investigated in aerated 3.5% NaCl aqueous solution. The corrosion resistance of the alloy with different aging times is analyzed by measuring potentiodynamic polarization, electrochemical impedance spectroscopy. The surface morphology is examined by scanning electron microscopy. The results demonstrated that the corrosion resistance of the alloy in the peak-aged condition is worse than the other conditions. Accordingly, corrosion rate and the corrosion current density of the alloy reach its maximum value. An Fe-rich phase is identified as the β-Al4.5FeSi phase by atomic-resolution high angle annular dark field scanning transmission electron microscopy and energy dispersive X-ray spectroscopy mapping analyses. The β-Al4.5FeSi is wrapped slowly by the precipitates of Mg2Si from the process of the peak-aged condition to the over-aged condition. It is hypothesized that the change of corrosion behavior of the alloy may be attributed to the β-Al4.5FeSi wrapped slowly by the precipitates of Mg2Si.

Previously known to form only under high pressure synthetic conditions, here we report that the T′-type 214-structure cuprate based on the rare earth atom Tb is stabilized for ambient pressure synthesis through partial substitution of Pd for Cu. The new material is obtained in purest form for mixtures of nominal composition Tb1.96Cu0.8Pd0.2O4. The refined formula, in orthorhombic space group Pbca, with a = 5.5117(1) Å, b = 5.5088(1) Å, and c = 11.8818(1) Å, is Tb2Cu0.83Pd0.17O4. An incommensurate structural modulation is seen along the a axis by electron diffraction and high resolution imaging. Magnetic susceptibility measurements reveal long-range antiferromagnetic ordering at 7.9 K, with a less pronounced feature at 95 K; a magnetic moment reorientation transition is observed to onset at a field of approximately 1.1 T at 3 K. The material is an n-type semiconductor.

Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a thin dielectric, and thin separated metal top-surface structures. The dielectric SiO2 strongly absorbs near 9 µm wavelength and has correspondingly strong long-wave-infrared (LWIR) dispersion for the refractive index. This dispersion results in multiple absorption resonances spanning the LWIR, which can enhance broad-band sensitivity for LWIR bolometers. Similar considerations apply to silicon nitride Si3N4. TiO2 and AlN have comparatively low dispersion and give simple single LWIR resonances. These dispersion-dependent features for infrared MIM devices are demonstrated by experiment, electrodynamic simulation, and an analytic model based on standing waves.

We studied the effect of annealing on magnetic properties and structure of Heusler-type NiMnGa glass-covered microwires with a metallic nucleus diameter of about 22 μm prepared using the Taylor–Ulitovsky method. The as-prepared NiMnGa glass-covered microwires do not present ferromagnetic order at room temperature. Magnetization curves of the as-prepared samples do not present either saturation or coercivity at temperatures above 5 K. After annealing of the microwires, a ferromagnetic ordering is obtained with a Curie temperature of about 300 K which is beneficial for magnetic solid state refrigeration. The hysteresis observed on temperature dependence of magnetization in annealed samples and magnetic softening at about 260 K has been interpreted as the first-order phase transformation. Observed changes have been discussed considering internal stress relaxation after annealing, nanocrystalline structure of the as-prepared and annealed samples, recrystallization process and magnetic ordering of phases identified in the as-prepared sample and appearing under recrystallization. Existence of insulating and flexible glass-coating is beneficial for improvement of mechanical properties but the glass coating considerably affects magnetic properties of NiMnGa microwires. Therefore special attention must be paid to annealing conditions for realization of martensitic transformation.