Copper nanoparticles (Cu-NPs) were prepared in virgin coconut oil (VCO) using a laser ablation technique. A copper plate immersed in VCO was irradiated by an Nd:YAG laser at wave lengths of 532 nm for 5, 10, 20, and 30 min. By increasing the ablation time from 5 to 30 min, the particle size inside the nanofluid decreased from 11 to 4 nm and the concentration, refractive index, and the volume fraction of copper nanofluid increased. The Cu-NPs were capped with oxygen from hydroxyl groups of the VCO, as verified by Fourier transform infrared spectroscopy. The refractive indices, obtained by analysis of the surface plasmon resonance signals increased from 1.44371 + 0.0034i to 1.44387 + 0.0142i, and special self-phase modulation due to nonlinearity effect was investigated.

The influence of calcium fluoride (CaF2) on combustion characteristics of Na2WO4 + 3 Mg system and microstructure of the produced W and WO3/W crystals is investigated. The results of thermodynamic analysis and experimental investigations show that CaF2 simultaneously enhances the conversion of Na2WO4 toward tungsten and binds sodium through the formation of NaF phase. The examination of the microstructure of quenched combustion products and differential scanning calorimetry analysis indicate that at early stages of combustion, a part of Na2WO4 is reduced by Mg to tungsten, whereas another part reacts with CaF2 forming CaWO4 and NaF. Subsequent magnesium reduction of CaWO4 significantly increases the overall temperature of the combustion process. Such modification in reaction mechanism coupled with postcombustion processing (e.g., acid/basic treatment) of the product allows us to produce either pure tungsten nanocrystals or tungsten oxide—tungsten nanostructures consisting of two-dimensional WO3 nanoflakes assembled on a W core. It is found that CaF2 does not influence the sizes of tungsten nanocrystals. However, since the addition of CaF2 leads to the increase of overall reaction temperature, it facilitates the formation of W particles with equilibrium crystal shape by faceting process.

Novel water-soluble titanium complexes coordinated by hydroxycarboxylic acids or amines were developed, and the hydrothermal treatment of the new complexes was carried out to elucidate the formation mechanism of the titania polymorphs including rutile, anatase, and brookite. An empirical relationship among the crystal structure of TiO2, the ligand, and the complex structure was found. Anatase, rutile, or a mixture of both was obtained by the hydrothermal treatment of the complexes coordinated by hydroxycarboxylic acids. The structure of complexes prepared using hydroxycarboxylic acids, which have one hydroxyl and one carboxylic groups, seems to be preferable for the formation of rutile. It was also found that the hydrothermal treatment of titanium complexes coordinated by amine with NAc2 structure resulted in the formation of brookite. Thus, the effect of ligand and complex structure on the crystal structure of TiO2 synthesized by the hydrothermal treatment of the complexes was proposed.

A novel graphene-modified LiMnPO4 composite as a performance-improved cathode material for lithium-ion batteries has been prepared with LiH2PO4, Mn(CH3COO)2·4H2O, and graphite oxide (GO) suspension by spray-drying method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and galvanostatic charge–discharge tests are applied to characterize these materials. The structure analysis shows that LiMnPO4 sheets with width of 100–200 nm and thickness of 20–30 nm are attached to the graphene sheets in pieces. The graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during the discharge/charge process. The electrochemical tests show that the composite cathode material could deliver a capacity of 105.1 mAh/g at 0.05 C in the voltage range of 2.5–4.4 V. Moreover, the cells showed fair good cycle ability over 50 cycles.

Spider dragline silk is a self-assembling protein that rivals many engineering fibers in strength, extensibility, and toughness, making it a versatile biocompatible material. Here, atomistic-level structures of wildtype MaSp1 protein from the Nephila clavipes spider dragline silk sequences, obtained using an in silico approach based on replica exchange molecular dynamics and explicit water, are subjected to nanomechanical testing and released preceding failure. We approximate the relaxation time from an exponential decay function, and identify permanent changes in secondary structure. Our work provides fundamental insights into the time-dependent properties of silk and possibly other protein materials.

It is widely believed that switching to the conductive state in memristive materials is triggered by the external field that drives defect dynamics. In polycrystalline materials, grain boundaries are further believed to cause switching by enabling faster defect motion. Here, we report a first-principle study of oxygen vacancy dynamics at a grain boundary (GB) in polycrystalline ZnO and show that switching to the conductive state is triggered by a recombination-enhanced motion of vacancies perpendicular to the GB. We call this mechanism the “breathing” trigger of memristive switching.

State-of-the-art colloidal quantum dots (CQDs) exhibit excellent properties as pure color red, green, and blue (RGB) phosphors for light-emitting applications ranging from solid-state lighting to flat panel displays. Progress in controlling the chemical synthesis of II–VI semiconductor nanocrystals has enabled a better understanding of the fundamental physical processes that dictate their interactions with light at the quantum level. In this article, we review recent work that extends this understanding and the corresponding utility to a higher excitation regime, where optical gain and laser action have been demonstrated across the RGB color spectrum from a single material. Recent developments have surmounted some fundamental challenges to CQDs for optical gain and have made gains toward their possible future as full-color palette lasers.