In this work, the effect of temperature, in the range of 25 to 250 °C, on deformation twinning in textured polycrystalline pure magnesium (Mg) was investigated. Compression loading was applied perpendicular to the c-axis texture direction. The yield strength and strain hardening rate are shown to drastically decrease with increasing temperature with total suppression of twinning at 200 °C. This behavior is attributed to the decrease in the critical resolved shear stress for prismatic slip and temperature insensitivity of tensile twinning. These results provide a first step in fundamentally understanding the deformation of Mg at elevated temperatures and quantify the mechanisms that lead to their improved formability at elevated temperatures.

BiFeO3 (BFO) p-type semiconducting nanofibers were deposited on fluorine-doped SnO2 substrates by a combination of electrospinning (BiFeO3) and spin-coating (Fe2O3) procedures. Photocurrent density values of BFO nanofibers which increased with the annealing temperature to values six times larger were obtained. Different amounts of BFO nanofibers (5, 10, and 25 wt%) were also integrated into α-Fe2O3 films. The photocurrent density of the α-Fe2O3/BFO nanofiber films had the highest value for a 10 wt% BFO nanofibers. The anisotropy in charge transport due to the underlying nanofibrous pathways which prevented the charge carrier recombination was the main cause for the enhancement of the photocurrent density.

Sinnerite (Cu6As4S9) is a semiconductor computed to have attractive optoelectronic properties, but little attention has been paid to its experimental synthesis and characterization. Here, the authors report the first synthesis of polycrystalline sinnerite thin films. By heating Cu3AsS4 nanoparticles in sealed ampoules with As2S2 powder, a phase transformation to Cu6As4S9 is achieved along with the formation of micron-sized dense grains appropriate for device applications. The films display a bandgap of ~1.2 eV, significant photocurrent generation under simulated AM1.5 illumination, and carrier lifetimes nearing 1 ns, demonstrating the promise of sinnerite for use in photovoltaic applications.

A new theta geometry was developed for microscale bending strength measurements. This new “gap” theta specimen was a modification of the arch theta specimen that enabled microscale tensile testing. The gap theta specimen was demonstrated here on single-crystal silicon, microfabricated using two different etch processes. The resulting sample strengths were described by three-parameter Weibull distributions derived from parameters determined using established arch theta strengths, assuming a specimen-geometry and -size invariant flaw distribution and an approximate loading configuration.

Nickel thin films were prepared by electroless plating in a foam of electrolyte generated by bubbling nitrogen into a hypophosphite-based electroless plating solution added with surfactants of sulfuric acid monododecyl ester sodium salt and ammonium pentadecafluorooctanoate (APFO). Ferroxyl test revealed that the films deposited in foam had substantially higher corrosion resistance than those deposited in liquid. Even with a film thickness of only 1.5 µm, the fraction of corroded area was as small as 0.002% when the film was deposited in the foam. The notable improvement in the corrosion resistance was made possible by adding APFO as the surfactant.

Nitric oxide (NO) acts a pivotal role in regulating various physiological processes of vasodilation, platelet aggregation, and vascular smooth muscle cell mitogenesis and proliferation. This makes NO a promising candidate for the treatment of cardiovascular problems like hypertension and vascular stenosis. However, the high reactivity of NO poses an issue for effective NO delivery. To overcome this limitation, recent developments on three-dimensional (3D) materials have been explored with either physical or chemical incorporation of NO releasing donors, to provide spatiotemporal control over NO-signaling pathways in blood vessels. Here, we offer an overview on the current efforts, and propose future perspectives for precise regulation on NO delivery in advanced 3D materials toward proper vascular functionality.

The rise of additive manufacturing (AM) has enabled the rapid production of complex part geometries across multiple material domains. To date, however, AM of inorganic semiconductor materials has not been fully realized due to the difficulty of forming single-crystal materials with traditional AM processes. Here, we demonstrate a novel semiconductor synthesis method using a combination of liquid and gas precursors to additively print gallium nitride. Growth rates of 1–2 µm/min are demonstrated in printed regions while maintaining epitaxial alignment with the substrate. We also outline critical variables for the future development, improvement, and implementation of the proposed process.

Highly graphitic carbons are obtained by precipitating carbon from molten steel inoculated with bismuth. Scanning electron microscopy images show that the products have a potato peel morphology. The inoculant leads to a breaking of the local symmetry of the graphitic structure as evidenced by Raman spectroscopic studies. The products exhibit flat charge–discharge profiles below about 200 mV versus Li+/Li, reversible capacities even exceeding the theoretical limit of 372 mAh/g for perfectly graphitic structures, low first-cycle irreversible capacities, and sustained hundreds of cycles.

Five Au complexes are evaluated for the reduction reaction of CO2 via cyclic voltammetry and in a photocatalytic system. Electrochemically, the complexes were all evaluated for pre-association with CO2 prior to electrochemical reduction and for thermodynamic favorability for CO2 reduction in photocatalytic systems. The complexes were evaluated in photocatalytic reactions using an Ir-based photosensitizer and a sacrificial electron donor for the conversion of CO2 to CO. Au-complex counterion effects on the photocatalytic reaction were analyzed by varying weakly coordinating counterions with significant performance changes noted. At low Au-complex concentrations, a high TON value of 700 was observed.

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.

Nickel thin films were prepared by electroless plating in a foam of electrolyte that was generated by bubbling nitrogen gas into a hypophosphite-based electroless plating solution to which was added a surfactant of sulfuric acid monododecyl ester sodium salt. Although the film growth rate in the foam was considerably lower than that in the conventional liquid, film growth was enhanced by inducing a flow in the foam. Compared with films deposited in liquid, the films deposited in foam had a smaller number of pinholes, smaller crystallite size, and superior corrosion resistance. The ferroxyl indicator test showed that the area of corrosion can be reduced to less than 1/20 by depositing the film in foam instead of liquid.

Millions of micro electro mechanical system sensors are fabricated each year using an ultra-clean process that allows for a vacuum-encapsulated cavity. These devices have a multi-layer structure that contains hidden layers with highly doped silicon, which makes common imaging techniques ineffective. Thus, examining device features post-fabrication, and testing, is a significant challenge. Here, we use a combination of micro- and nano-scale x-ray computed tomography to study device features and assess failure mechanisms in such devices without destroying the ultra-clean cavity. This provides a unique opportunity to examine surfaces and trace failure mechanisms to specific steps in the fabrication process.

A correction method for linear hardening materials is brought forward to obtain the true (or nearly true) modulus of cylindrical specimens with middle aspect ratios in compression tests. By considering the stress concentration near the interface between the specimen and the compression platen caused by slanted contact, a “sandwich” model is developed. A correction formula is derived and all parameters can be obtained from the tested stress–strain curve. Experiments were performed on Al 2024 specimens with four aspect ratios. The corrected results are closer to the intrinsic modulus than the tested values, which verify the effectiveness of the correction method.

Indentation and scratch models are proposed to numerically investigate effects of compressive prestress on film's mechanical responses. In indentation, normal stress distributions are strongly dependent on film thickness; the applied force and the maximum normal stresses with a prestress are much larger than without prestress. For various film thicknesses the change in the normal force in scratch between the non-prestressed and prestressed films is 4%–23%. The scratch friction coefficient is larger with prestress than without prestress. With biaxial or uniaxial prestress the material becomes more difficult to deform or to slide at the contact surface compared with cases without prestress.

Machinable mica glass ceramics were synthesized by sintering method. The crystal phase was characterized using x-ray diffraction, showing that the main crystal phase was fluorophlogopite. Mechanical properties were measured at different temperatures. The results demonstrated that bending strength and fracture toughness increased 28% and 24% when temperature decreased from 300 to 77 K, respectively. Compressive strength also increased at cryogenic temperatures, but a higher value was obtained at 195 K. According to scanning electron microscope observation, the extraction of mica platelets was observed at 77 K, which may be the toughening mechanism of machinable mica glass ceramics.

Physical understanding of crack propagation is a fundamental issue in the industry. In the literature, crack velocities of polymer materials are strongly dependent on their visco-elastic properties and energy release rates. Recently, numerical and theoretical studies have proposed that structural sizes in polymers also influence on crack propagation. Here, using polymer sheets with similar visco-elastic properties but with different pore sizes, we vary explicitly the representative structural size and examine the effect of the size on crack propagation. Findings in this work help us to understand crack propagation in polymer materials and bio-inspired materials which have porous structures.

The flow of particles through confined volumes has appeared under different contexts in nature and technology. Some examples include the flow of red blood cells or drug delivery vehicles through capillaries, or surfactant-based particles in nano- or microfluidic cells. The molecular composition of the particles along with external conditions and the characteristics of the confined volume impact the response of the particle to flow. This review focuses on the problem of phospholipid vesicles constrained to flowing in channels. The review examines how experimental and computational approaches have been harnessed to study the response of these particles to the flow.

Zirconium thin films were irradiated at room temperature with an 800 keV Zr+ beam using a 6 MV HVE Tandem accelerator to 1.36 displacement per atom damage. Freestanding tensile specimens, 100 nm thick and 10 nm grain size, were tested in situ inside a transmission electron microscope. Significant grain growth (>300%), texture evolution, and displacement damage defects were observed. Stress–strain profiles were mostly linear elastic below 20 nm grain size, but above this limit, the samples demonstrated yielding and strain hardening. Experimental results support the hypothesis that grain boundaries in nanocrystalline metals act as very effective defect sinks.