Mechanical strain triggers changes in inherent molecular structure, especially in polymeric and biological materials. Unlike conventional techniques, we demonstrate a novel dynamic mechanical characterization method to study the effect of this structural evolution with strain on elastic properties. During tensile characterization of small diameter fibers, we quantitatively measured the viscoelastic properties as a continuous function of strain. While this approach is useful to characterize the elastic properties of metal microwires independent of applied strain, it is extremely important for fundamental understanding of molecular changes and their effect on the viscoelastic properties in materials such as polymer fiber and spider silk.

We previously demonstrated that electrode architectures comprising nanoscale birnessite-like MnOx affixed to three-dimensional carbon nanofoam (CNF) scaffolds offer performance advantages when used as cathodes in rechargeable zinc-ion cells. To discern chemical and physical changes at the MnOx@CNF electrode upon deep charge/discharge in aqueous Zn2+-containing electrolytes, we deploy electroanalytical methods and ex situ characterization by microscopy, elemental analysis, x-ray photoelectron spectroscopy, x-ray diffraction, and x-ray pair distribution function analyses. Our findings verify that redox processes at the MnOx are accompanied by reversible precipitation/dissolution of crystalline zinc hydroxide sulfate (Zn4(OH)6(SO4)·xH2O), mediated by the more uniformly reactive electrode structure inherent to the CNF scaffold.

Neurological and psychiatric disorders account for an increasing proportion of the global disease burden. Correspondingly the neuropharmaceutical industry has experienced a significant contraction in recent years resulting in a poor variety of therapies available to treat an expanding range of conditions. Perhaps the greatest contributor to this failure in drug-discovery is the lack of understanding of the underlying biology of the nervous system and how molecular scale events translate into macroscale pathologies. Due to the unique nature of the human nervous system commonly used model organisms are often poorly representative of human pathologies resulting in a need for the development of advanced in vitro models that are capable of faithfully modeling complex structures within the brain. In this prospective, strategies for the generation of neuronal circuits and cultivation of complex three-dimensional (3D) cultures are explored. Frequently these constructs provide valuable insights into systems and processes that are difficult to explore in vivo due to the isolated and delicate nature of neuronal tissues. New developments are required to assess the physiological functions of 3D tissues in vitro.

Catalyst development is needed to enable the use of renewable electricity to chemically convert carbon dioxide (CO2) and water into fuels and chemicals, a more sustainable, lower-carbon alternative to conventional processes that produce fuels and chemicals based on fossil resources. In this study, the catalytic activity and selectivity of polycrystalline platinum (Pt) is thoroughly characterized for the CO2 reduction reaction, based on an electrochemical cell design that offers high sensitivity for product detection. Thin polyaniline films are then electrodeposited onto polycrystalline Pt foils to form hybrid organic–inorganic surfaces. The addition of the polymer is observed to have an impact on the catalytic chemistry, yielding up to a fivefold enhancement in formate and CO production over pure Pt foils. This work elucidates new strategies to perturb interfacial chemistry in a manner that could help steer CO2 electro-reduction catalysis in desired directions.

Herein, we show that scanning probe microscopy (SPM) is an effective tool permitting to disclose the nature of the colossal dielectric permittivity characteristic of CaCu3Ti4O12 (CCTO) compound. SPM data confirm the existence of micro- and nanoscale barrier layer capacitance mechanisms which simultaneously contribute to the electrical conductivity of the material. The former mechanism is associated with the potential grain-to-grain barriers. The latter mechanism involves the barriers created by intragrain structural defects. The results of the SPM study shed new light on the origin of the colossal dielectric constant in CCTO.

Barium titanate (BTO) is a ferroelectric perovskite with potential in energy storage applications. Previous research suggests that BTO dielectric constant increases as nanoparticle diameter decreases. This report recounts an investigation of this relationship. Injection-molded nanocomposites of 5 vol% BTO nanoparticles incorporated in a low-density polyethylene matrix were fabricated and measured. Finite-element analysis was used to model nanocomposites of all BTO sizes and the results were compared with experimental data. Both indicated a negligible relationship between BTO diameter and dielectric constant at 5 vol%. However, a path for fabricating and testing composites of 30 vol% and higher is presented here.

Additive manufacturing, also known as three-dimensional printing, has provided a promising solution to produce near-net shape components directly from metallic powder. However, their surface roughness still prevents them from immediate use; finish machining is usually required. This study has investigated the grain size variation and saw-tooth/shear-band spacing during the machining of titanium alloy (Ti–6Al–4V) printed using direct metal deposition. Grain refinement was observed within both the printed and substrate regions, and their grain structures retained the basket-weave Widmanstätten and bimodal structures, respectively. The saw-tooth spacing decreased as the build height increased.

The synergistic effects of the template [Pluronic-123 (P123)] and the silica source [tetraethoxysilane (TEOS)] concentrations on the SBA-15 mesoporous silica morphology were investigated through adjusting the system initial solution volume with the same amounts of silica source and template. It found interestingly that the SBA-15 morphology changed from the hexagonal plate-like shape to the gear-like shape with the decrease of the P123 and TEOS concentration. Based on the morphology variations, the growth of the gear-like morphology was speculated to be formed through the preferential growth at the corner and the layer-by-layer growth in the end face of the ordinary hexagonal plate-like particle.

The strength of single-crystalline nanoscale metals is controlled by dislocation nucleation from free surfaces. Surface properties such as crystallographic orientation, surface stress, and surface diffusion have been proposed as key parameters that control dislocation surface nucleation, but have not been confirmed experimentally. To investigate the influence of surface parameters, in situ scanning electron microscope mechanical testing is used to compress defect-free Ag and Cu nanocubes that are passivated with organic surfactants in order to tune their surface properties. Comparison between passivated nanocubes indicates that yield strength may depend on surfactant binding energy, but is also dependent on intrinsic material properties.

Allylamine (AA)-functionalized surfaces for cell adhesion and tissue engineering generated by plasma reactions present several disadvantages, such as amine degradation after 1 week of storage in air and difficulty in achieving a highly specific surface functionalization. In this work, polypropylene (PP) and polyethylene (PE) films were functionalized with AA by γ irradiation to enhance adhesion and compatibility without changing intrinsic bulk properties, thus avoiding the disadvantages of plasma synthesis. Irradiation grafting was realized by a direct and pre-irradiation oxidation method. The effect of different parameters studied were characterized by Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and contact angle measurements.

Metal–air batteries promise higher energy densities than state-of-the-art Li-ion batteries and have, therefore, received significant research attention lately. The most distinguishing feature of this technology is that it takes advantage of reversible conversion reactions of O2 or other air components (such as N2 or CO2) at the cathode. To promote these reactions, catalysts are often needed. A large number of materials have been studied for this purpose. In the present paper, we discuss the roles played by catalysts in metal–air battery systems. In particular, we choose to focus the discussions on the Li–O2 batteries as they are most intensely studied in the literature. Within this context, catalysts are often shown effective to facilitate the oxygen (O2) reduction reactions and/or O2 evolution reactions. The overall cell performance as measured by the round-trip efficiencies and charge/discharge rates can be significantly improved by the incorporation of catalysts. However, the presence of catalysts is also found to complicate the chemical reactions as they often exhibit activities toward parasitic chemical reactions such as electrolyte and electrode decompositions. The issue is especially acute in aprotic Li–O2 batteries, where organic electrolytes and reactive O2 species are mixed. In addition to heterogeneous catalysts, we also discuss the roles played by homogeneous catalysts as redox mediators, which are effective to promote redox reactions that are critical to energy storage applications.

Indium tin oxide (ITO) has become a very useful plasmonic and nonlinear optical material because of its highly tunable electrical and optical properties and strong optical nonlinearity. In this work, the authors conducted detailed fabrication process studies by using high-temperature reactive sputtering to finely tune the optical properties of ITO thin films, particularly the epsilon-near-zero (ENZ) wavelength in the near and mid-IR spectrum. Sputtered ITO thin films are characterized by using spectroscopic ellipsometry, surface profilometry, Hall measurements, and 4-point probe testing. Additionally, the effect of post-deposition annealing of ITO films is also investigated.

We deposited TaWSi amorphous metal thin films to determine how composition affects film crystallization and oxidation at high temperatures. Films were deposited by magnetron sputtering from targets of nominal compositions Ta : W : Si = 40 : 40 : 20, 30 : 50 : 20, and 30 : 30 : 40, and studied by electron probe microanalysis, electron microscopy, electrical methods, x-ray diffraction, x-ray photoelectron spectroscopy, and atomic-force microscopy. All films remained amorphous to 800 °C or higher temperatures. Films prepared from the target composition 30 : 30 : 40 yielded the film composition Ta41.7W38.4Si19.9, which retained its film integrity and amorphous structure to 1100 °C, even after annealing in air.

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.

End-stage renal disease (ESRD) is a life-threatening illness that presents significant healthcare challenges. About 90% of ESRD patients receive hemodialysis treatment, but the currently available hemodialysis systems are bulky and prone to complications. We report the design of a microfluidic hemodialysis device composed of two polydimethylsiloxane (PDMS) chambers separated by a cellulose ester (CE) membrane. The polyethylene glycol-passivated PDMS and CE surfaces reduced platelet adhesion by 74% and 86%, respectively. Moreover, the device exhibited a higher urea clearance rate per unit area than a healthy kidney. The reported design sets the foundation for a next-generation biomimetic portable hemodialysis device.

Inspired by the recently reported translucency of monolayer graphene (GE) to wetting, atomistic simulations are employed to evaluate water flow enhancement induced by GE deposited on the inner surfaces of hydrophilic nanochannels. The flow in the coated channels exhibits a slip length of approximately 3.0 nm. Moreover, by contrasting the flow rates in channels with coated walls against flow rates in the corresponding uncoated channels, an “effective” flow enhancement from 3.2 to 3.7 is computed. The probability density function of the water dipole orientation indicates that the flow enhancement is related to a thinner structured water layer at the solid–liquid interface. This study provides quantitative evidence that GE employed as coating reduces substantially hydraulic losses in hydrophilic nanoconfinement.

Inkjet printing is a promising technology providing cost-effective method for processing various materials on deformable substrates. In this work, linear and serpentine inkjet printed interconnects on two different substrates were fabricated and electromechanically characterized. A particular attention was given to the optimization of the process parameters; high quality can be achieved only printing slowly in vertical direction and optimizing the drop spacing to the specific pattern. The electromechanical results showed that the geometrical layout and printing direction strongly affect the printing quality and the electromechanical response; serpentine shapes should be preferred to straight interconnects as better gauge factors are obtained.

Si-TiN alloys are attractive for use as negative electrodes in Li-ion cells because of the high conductivity, low electrolyte reactivity, and thermal stability of TiN. Here it is shown that Si-TiN alloys with high Si content can surprisingly be made by simply ball milling Si and Ti powders in N2(g); a reaction not predicted by thermodynamics. This offers a low-cost and simple method of synthesizing these attractive materials. The resulting alloys have smaller grain sizes than Si-TiN made by ball milling Si and TiN directly, giving them high thermal stability and improved cycling characteristics in Li cells.

Sample geometry effects on mechanical strengths of gold micro-cantilevers are evaluated by a micro-bending test. Six micro-cantilevers with the same length of 50 μm are prepared, and the width and the thickness are varied to examine individual effects on the yield stress. The yield stress increases from 428 to 519 MPa when the thickness decreases from 11.1 to 6.0 μm. No obvious dependency is observed when varying the width. The results reveal that the thickness and the width each has a different influence on the yield stresses of micro-cantilevers evaluated by the bending test, which is the sample geometry effect.

Tin oxide (SnO2) hollow spheres modified with titanium dioxide (TiO2) nanowires (NWs) synthesized by sequential hydrothermal reactions were investigated as photoanodes for dye-sensitized solar cells. Not only does the hydrothermal treatment form numerous short TiO2 NWs on the surface of SnO2 spheres, but also passivates the surface of SnO2. Consequently, the specific surface area of the photoanode and dye loading are almost doubled, at the same time the surface defects and charge recombination are both appreciably reduced. As a result, the short-circuit photocurrent density and open-circuit photovoltage both greatly increased. The power conversion efficiency of the solar cells increases from 0.4% to 2.9%.