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Rubberlike insect cuticle is a light fibrous composite, which exhibits great deformability and long-range elasticity due to the presence of a large amount of the elastomeric protein resilin. The presence of resilin in specific locations in the insect body leads to the assumption that its main function is loss-free storage of energy. Rubberlike cuticle was identified, for the first time, in the femur base of the sand field cricket, Gryllus firmus, using fluorescence microscopy and various staining methods. Dynamic nanoindentation testing was then used to investigate the differences in the mechanical properties of rubberlike cuticle between males and females and wing morphs of this species. Significant changes in storage, loss moduli, and resilience were captured between female wing morphs. The results provide insight into the structure–function relations associated with the properties of insect joints from different morphs and genders.
Fe3O4@TiO2 magnetic photocatalysts containing sub-10-nm TiO2 nanocrystals with two different morphologies (nanoparticles and nanorods) were prepared via a facile straight dipping process. A series of comparative experiments on organic pollutant degradation demonstrated that Fe3O4@TiO2 nanorods show superior activity and faster degradation rates than Fe3O4@TiO2 nanoparticles. Combined with the study of high resolution transmission electron microscopy, crystal models are given to analyze the morphology effect of TiO2 nanocrystals on their photocatalytic activities for organic degradation. TiO2 nanorods with more (100) crystal planes, which have relatively higher surface energy and relative higher density of Ti atoms, showed a higher activity than that of TiO2 nanoparticles. Furthermore, both Fe3O4@TiO2 nanorods and Fe3O4@TiO2 nanoparticles show better photocatalytic activities than several comparison Fe3O4@TiO2 samples due to the strong size effect arising from the tiny size of TiO2 nanorods and nanoparticles. These magnetic photocatalysts also show advantages in separation and recycling utilization.
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.
X-ray powder diffraction data, unit-cell parameters, and space group for potassium erbium fluoride, K0.5Er0.5F2, are reported [a = 5.6862(5) Å, unit-cell volume V = 183.85 Å3, Z = 4, and space group Fm-3m]. Potassium erbium fluoride is isostructural with a large family of fluorides represented by the mineral fluorite CaF2. All of the measured lines of the title compound were indexed and are consistent with the Fm-3m space group. No detectable impurities were observed.
We report here the fabrication and characterization of ultra-long AlN whiskers by physical vapor transport method. The obtained whiskers are 1–3 µm in diameter and up to millimeters in length. The whiskers grow along the [0001] crystallographic direction and are well crystallized. They exhibit a strong ultraviolet emission at 345 nm, the shortest wavelength reported in AlN whiskers or nanowires. Our results indicate that these large scales of AlN whiskers are less contaminated by oxygen and other impurities compared with the previously reported ones, which may find wide applications in fabricating ultraviolet optoelectronic devices.
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.
Twenty-seven scapolite samples from various localities and with compositions between Me6–93 were obtained using electron microprobe analysis (EMPA). Their unit-cell parameters were obtained using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and Rietveld structure refinements using space group P42/n. The EMPA data show the well-known discontinuity at Me75. In addition, the unit-cell parameters, especially c, show a discontinuity at Me75 (=five Al atoms per formula unit, apfu), ideally NaCa3[Al5Si7O24](CO3), where the scapolite solid solution is divided into two (Me% = [Ca/(Ca + Na + K)] × 100). A maximum c parameter value occurs at Me37.5 (=four Al apfu ideally), where complete Al–Si, Na–Ca, and Cl–CO3 order occurs. The unit-cell volume, V, varies smoothly with Me% and Al apfu across the series.
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.