Using an effective Hamiltonian of mutiferroic BiFeO3 (BFO) as a toy model, we explore the effect of the coefficient, C, characterizing the strength of the spin–current interaction, on physical properties. We observe that for larger C values and below a critical temperature, the magnetic moments organize themselves in a novel cycloid, which propagates along a low-symmetry direction and is associated with a structural phase transition from polar rhombohedral to a polar triclinic state. We emphasize that both of these magnetic and structural transitions are results of a remarkable self-organization of different solutions of the spin–current model.

In this paper, the Lewis base character of 3-aminopropyltrimethoxysilane (3-APTMS), an imine derivative of siloxane, and an indole monomer were shown to enable the reduction of gold cations in acetone. The Lewis acid–base adduct of indole monomers and gold formed a polyindole–gold nanoparticle sol. Similarly, the Lewis acid–base adduct of 3-APTMS and gold enabled the formation of gold nanoparticles in the presence of acetone. The polyindole–gold nanoparticle sol and siloxane–gold nanoparticles underwent self-assembly into a polymeric nanofluid that was suitable for casting membranes. The use of these membranes as a potentiometric ion sensor for both cations and anions was considered; a common nonspecific ion exchange molecule, sodium tetraphenylborate, and the polymeric nanofluid were used to prepare an anion sensor and a cation sensor.

Direct urea fuel cells were fabricated using CuNi-plated polymer cloth for anode catalyst and current collector, and Pt-black for cathode catalyst. The output power was significantly enhanced by coating the CuNi cloth with a conducting polymer, poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT*PSS). The open circuit voltage, 0.80 V and the maximum output power, 3.0 mW/cm2 were obtained for the fuel of 0.5 M urea water solution under ambient conditions. Improvement over the cell structure demonstrated to lighten a light emitting diode.

Low-cost, earth-abundant magnetocaloric materials (MCMs) are required for energy-efficient, green, and affordable magnetic cooling technology. We investigated the magnetic and magnetocaloric properties of rare-earth-free Fe75−xCrxAl25 (19≤x≤25) arc-melted alloys. The Curie temperature (Tc) of these alloys could be tuned from 220 K up to room temperature by Cr additions. The relative cooling power/US$ was found to be superior to other promising MCMs. Fe50Cr25Al25 ball-milled powders, with an average particle size of ~25 nm, were used to prepare magnetic fluid. Maximum cooling (ΔT) of 5.4°C was observed for Fe50Cr25Al25-based fluids.

The preparation, screening, and characterization of affinity membranes require a deep knowledge of the behavior of all components of the affinity material. Several studies report the effect of different spacers in combination with the ligand molecule, but the effect of the spacer arm “per se” is generally disregarded. The effect of the spacer 1,2-diaminoethane on non-specific protein adsorption was recently investigated and the results were compared with the ones obtained with A2P affinity membranes. The results show that this spacer has indeed an important effect and that similar specific studies need to be performed for every spacer molecule.

We analyze the optical properties of composite materials that combine nanowire and nanolayer platforms. We revisit effective-medium theory (EMT) description of wire materials with high filling fraction positioned in anisotropic unit cells and present a simple numerical technique to extend Maxwell–Garnett formalism in this limit. We also demonstrate that the resulting EMT can be combined with transfer-matrix technique to adequately describe photonic band gap behavior, previously observed in epitaxially grown semiconductor multilayer nanowires.

Cationic PEGylated nanogels based on poly(N,N-diethylaminoethyl methacrylate) (PDEAEM) were prepared varying the ratio of PDEAEM to polyethyleneglycol (PEG), the initiator, and the crosslinker; resulting in nanogels of different surface charge (zeta-potential) and hydrodynamic diameter. Nanogels without PEG (100% PDEAEM) and nanogels containing 45 wt.% of PDEAEM were cytotoxic to human colon cancer cell line (HCT-116). Nanogels containing 20 wt.% or less of PDEAEM provided with a PEG shell were non-cytotoxic even at a concentration of 1 mg/mL. These nanogels loaded with 5-fluorouracil turned to be cytotoxic provoking cell death by apoptosis. Nanogels were also studied loaded with gold nanoparticles.

Atomic clusters attached to a low-dimensional system, called Fano defects, produce rich wave interferences. In this work, we analytically found an enhanced thermoelectric figure-of-merit (ZT) in periodic atomic chains with Fano defects, compared with those without such defects. We further study self-assembled DNA-like systems with periodic and quasiperiodically placed Fano defects by using a real-space renormalization method developed for the Kubo–Greenwood formula, in which tight-binding and Born models are respectively used for the electric and lattice thermal conductivities. The results reveal that the quasiperiodicity could be another ZT-improving factor, whose long-range disorder inhibits low-frequency acoustic phonons insensitive to local defects.

Metal–graphene composites are sought after for various applications. A hybrid light-weight foam of nickel (Ni) and reduced graphene oxide (rGO), called Ni-rGO, is reported here for small molecule oxidations and thereby their sensing. Methanol oxidation and non-enzymatic glucose sensing are attempted with the Ni-rGO foam via electrocatalytically, and an enhanced methanol oxidation current density of 4.81 mA/cm2 is achieved, which is ~1.7 times higher than that of bare Ni foam. In glucose oxidation, the Ni-rGO electrode shows a better sensitivity over bare Ni foam electrode where it could detect glucose linearly over a concentration range of 10 µM to 4.5 mM with a very low detection limit of 3.6 µM. This work demonstrates the synergistic effects of metal and graphene in oxidative processes, and also shows the feasibility of scalable metal–graphene composite inks development for small molecule printable sensors and fuel cell catalysts.

In this study, Vickers indentation was used to investigate the two-way shape-memory effect (TWSME) in an austenitic Ti-50.9 at.% Ni alloy, exposed to different heat treatments. Three aging treatments were used to manipulate the size of Ti3Ni4 precipitates. All samples were Vickers indented, and the indent depth was investigated as function of thermal cycling. The TWSME was found only in the material aged at 400 °C, which contained coherent precipitates. Thermal cycling shows stable TWSME, however, heating well above the austenite finish temperature lead to permanent austenitic protrusions. The results indicate that stabilized martensite plays a critical role in creating TWSME surfaces.

To gain a better understanding of the underlying mechanisms of neurological disease, relevant tissue models are imperative. Over the years, this realization has fuelled the development of novel tools and platforms, which aim at capturing in vivo complexity. One example is the field of biofabrication, which focuses on fabrication of three-dimensional (3D) biologically functional products in a controlled and automated manner. Herein, we provide a general overview of classical 3D cell culture platforms, particularly in the context of neurodegenerative disease. Subsequently, the focus is put on bioprinting-based biofabrication, its potential to advance 3D neuronal cell culture and, to conclude, the relevant translational bottlenecks, which will need to be considered as the field evolves.

Ternary sulfides and selenides in the distorted-perovskite structure (“chalcogenide perovskites”) are predicted by theory to be semiconductors with a band gap in the visible-to-infrared and may be useful for optical, electronic, and energy conversion technologies. Here we use computational thermodynamics to predict the pressure–temperature phase diagrams for select chalcogenide perovskites. Our calculations incorporate formation energies calculated by density functional theory, and empirical estimates of heat capacities. We highlight the windows of thermodynamic equilibrium between solid chalcogenide perovskites and the vapor phase at high temperature and very low pressure. These results can guide the adsorption-limited growth of ternary chalcogenides by molecular beam epitaxy.

Polarized resonant soft x-ray scattering (RSoXS) can leverage contrast between domains in mass, chemical bonds, and chain orientation to characterize polymer thin films. Although mass and chemical contrast can be predicted from the absorption spectra, the origins of orientational contrast are not fully understood. For example, in the case where one domain is crystalline, it is not obvious how the total crystallinity will affect the anisotropy. Using a simple calculation, we predict polarized RSoXS of model structures and compare with experiment. Through experiments and simulations, we demonstrate that scattering anisotropy is not monotonically related to local order but instead peaks when 50% of domains have aligned chains, i.e., when the sample is 50% crystalline.

Nanoindentation experiments have been carried on Arabidopsis thaliana using spherical tungsten tips. Load–displacement plots obtained from experiments suggest that there is an optimum diameter of tip size which can be used to safely penetrate the tip through the cell wall. Based on the exact tip size used in the experiments and the measured load–displacement response, the failure stress was calculated using the experimental data in conjunction with a computational model. The value of failure stress was investigated in hypertonic (plasmolyzed), isotonic, and hypotonic (turgid) samples.

We previously demonstrated that TiOx/Al2O3 nanolaminates (TAO NL) exhibit abnormally high-dielectric constant k (800–1000), due to Maxwell–Wagner polarization, via charge accumulation at insulating Al2O3/semiconducting TiOx interfaces. Here, we report TAO NL dielectric properties related to TiOx phase change in TiOx (0.9 nm)/Al2O3 (0.1 nm) NL. High-resolution transmission electron microscopy shows amorphous TiOx phase change to crystalline anatase TiO2 due to free-energy minimization. The phase change induce reduction in leakage current and dielectric loss (J = 10−2 to 10−4 A/cm2, tan δ = 10 to 10−1), still with k ~ 600 up to MHz, compared to amorphous TAO NLs.

Described is a simple one-pot route for the synthesis of hierarchically porous carbon supported palladium (Pd/C) monoliths with a three-dimensional pore network via self-assembly under basic conditions of a resol polymer. Textural and morphological characterization of the Pd/C monoliths was carried out using nitrogen sorption analysis and scanning electron microscope. Formation of Pd nanoparticles ranging from 35 to 60 nm was observed. Evaluation of catalytic activity for styrene hydrogenation was performed using the Pd/C material as heterogeneous catalyst in batch mode. Studies revealed that the monoliths showed leaching and catalytic activity similar to a commercial Pd/C catalyst.

The goal of this work was the modification of silicone rubber (SR) by radiation grafting of glycerol methacrylate (GlyMA) which was limited just on the surface, allowing the control of hydrophilicity and swelling properties. The grafted SRs were activated by derivatization of GlyMA to 2-oxoethyl methacrylate using sodium periodate, enabling the chemical immobilization of lysozyme by covalent bonds. The presence of lysozyme was confirmed by non-specific assay and by the enzymatic activity at 30 °C with Micrococcus lysodeikticus (coccus, Gram-positive). The materials were characterized by Fourier transform infrared spectroscopy-attenuated total reflectance, thermogravimetric analysis, water contact angle, and by mechanical properties as well as scanning electron microscope.

Here we report a general method for the synthesis of layered inorganic nanocrystalline materials using graphene oxide (GO) film as the template. Free-standing three-dimensional (3D) lamellar ZnO, α-Fe2O3, and reduced GO/ZnO hybrid structures were synthesized as examples. Such layered structures could also be exfoliated to obtain 2D assembled nanocrystal microsheets. The abundant nucleation sites on the GO surface and the compact stacking of GO platelets made it possible to tightly control metal oxide crystal size (~15 nm), alter preferential crystal growth direction, and assemble the nanocrystals into sheets, as confirmed by multiple characterization techniques.

Cellular adhesion depends on the integration of numerous signaling inputs generated by the chemical and physical properties of the substrate. The complex coupling among inputs makes it challenging experimentally to deconvolve their individual contributions to the adhesion process. To address this roadblock, we have employed a combination of electron beam and optical lithographic techniques to fabricate substrates with independently tunable topographical and chemical signaling cues. Arrays of gold nanostructures were patterned atop quartz substrates, half of which were etched into gold-capped nanopillars. Individual A549 cells exposed simultaneously to Arg-Gly-Asp-functionalized etched and non-etched arrays exhibited strongly preferential adherence to the nanopillars.

In this study, the formation solid solutions of titanium dioxide- zirconium dioxide (TiO2-ZrO2) system with the supercritical fluid method is described. The particles of solid solutions in the TiO2-ZrO2 system are spherical and form agglomerates, they are amorphous and have a size from 90 to 850 nm. The X-ray patterns of samples calcined above the temperatures of crystallization (450 °C) and phase transition (750 °C) demonstrate the decomposition of the solid solutions above the crystallization temperature and formation of phases in accordance with phase ratios in the TiO2-ZrO2 system at these temperatures. The formation solid solutions of the starting materials are observed in all region of concentrations.