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High-quality continuous uniform monolayer graphene was grown on polycrystalline PtRh20 alloy foils by low pressure chemical vapor deposition. The morphology of graphene was investigated by Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. Analysis results confirm that high quality single-layer graphene was fabricated on PtRh20 foil at 1050 °C using a lower flux of methane under low pressure. Graphene films were transferred onto the SiO2/Si substrate by the bubbling transfer method. The mobility of a test field effect transistor made of the graphene grown on PtRh20 was measured and reckoned at room temperature, showing that the carrier mobility was about 4000 cm² V-1 s-1. The results indicate that desired quality of single-layer graphene grown on PtRh20 foils can be obtained by tuning reaction conditions. [ABSTRACT FROM AUTHOR]

We report few-layer SnSe2 field effect transistors (FETs) with high current on/off ratios. By trying different gate configurations, 300 nm SiO2 and 70 nm HfO2 as back gate only and 70 nm HfO2 as back gate combined with a top capping layer of polymer electrolyte, few-layer SnSe2 FET with a current on/off ratio of 104 can be obtained. This provides a reliable solution for electrically modulating quasi-two-dimensional materials with high electron density (over 1013 cm-2) for field-effect transistor applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline RB 6 (R = Ce and Eu) have been successfully synthesized by a solid-state reaction of CeO 2 and Eu 2 O 3 with NaBH 4 at a temperature range of 900–1200 °C. Phase composition, grain morphology, microstructure and valence states of RB 6 were investigated by using XRD, FESEM, HRTEM and XANES measurements. Results show that all the synthesized hexaborides are composed of single-phase nanoparticles with cubic morphology. The FFT patterns of HRTEM images reveal that the hexaborides have a high crystallinity with CaB 6 -type cubic structure. The present preparation technique is as a novel and invaluable for the developments of highly crystallized RB 6 nanoparticles. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the presence of nerve growth factor (NGF) and its receptors tyrosine kinase A (TrkA) and p75 in the ovaries of the wild ground squirrels during the breeding and nonbreeding seasons. In the breeding period, NGF, TrkA and p75 were immunolocalized in granulosa cells, thecal cells, interstitial cells and luteal cells whereas in the nonbreeding period, both of them were detected only in granulosa cells, thecal cells and interstitial cells. Stronger immunostaining of NGF, TrkA and p75 were observed in granulosa cells, thecal cells and interstitial cells in the breeding season compared to the nonbreeding season. Corresponding for the immunohistochemical results, immunoreactivities of NGF and its two receptors were greater in the ovaries of the breeding season then decreased to a relatively low level in the nonbreeding season. The mean mRNA levels of NGF, TrkA and p75 were significantly higher in the breeding season than in the nonbreeding season. In addition, plasma gonadotropins, estradiol-17β and progesterone concentrations were significantly higher in the breeding season than in the nonbreeding season, suggesting that the expression patterns of NGF, and TrkA and p75 were correlated with changes in plasma gonadotropins, estradiol-17β and progesterone concentrations. These results indicated that NGF and its receptors, TrkA and p75 may be involved in the regulation of seasonal changes in the ovarian functions of the wild ground squirrel. [ABSTRACT FROM AUTHOR]

Revelation of emerging exotic states of topological insulators (TIs) for future quantum computing applications relies on breaking time-reversal symmetry and opening a surface energy gap. Here, we report on the transport response of Bi2Te3 TI thin films in the presence of varying Cr dopants. By tracking the magnetoconductance (MC) in a low doping regime we observed a progressive crossover from weak antilocalization (WAL) to weak localization (WL) as the Cr concentration increases. In a high doping regime, however, increasing Cr concentration yields a monotonically enhanced anomalous Hall effect (AHE) accompanied by an increasing carrier density. Our results demonstrate a possibility of manipulating bulk ferromagnetism and quantum transport in magnetic TI, thus providing an alternative way for experimentally realizing exotic quantum states required by spintronic applications. [ABSTRACT FROM AUTHOR]

Single crystalline strontium borate (SrB2O4) nanorods were synthesized for the first time viaa facile sol–gel route at low temperature. The SrB2O4nanorods have a good crystalline nature with the growth direction along the [511] orientation and they are transparent from the ultraviolet to the visible regimes. Nanoscale three-point bending tests were performed directly on individual nanorods to probe their mechanical properties using an atomic force microscope. The elastic modulus of SrB2O4nanorods was measured to be 158.2 ± 2.8 GPa, exhibiting a significant increase compared with other borate nanostructures and bulk borates. [ABSTRACT FROM AUTHOR]

We demonstrate the design and fabrication of a novel flexible nanoarchitecture by facile coating ultrathin (several nanometers thick) films of MnO2to highly electrical conductive Zn2SnO4(ZTO) nanowires grown radially on carbon microfibers (CMFs) to achieve high specific capacitance, high-energy density, high-power density, and long-term life for supercapacitor electrode applications. The crystalline ZTO nanowires grown on CMFs were uniquely served as highly conductive cores to support a highly electrolytic accessible surface area of redox active MnO2shells and also provide reliable electrical connections to the MnO2shells. The maximum specific capacitances of 621.6 F/g (based on pristine MnO2) by cyclic voltammetry (CV) at a scan rate of 2 mV/s and 642.4 F/g by chronopotentiometry at a current density of 1 A/g were achieved in 1 M Na2SO4aqueous solution. The hybrid MnO2/ZTO/CMF hybrid composite also exhibited excellent rate capability with specific energy of 36.8 Wh/kg and specific power of 32 kW/kg at current density of 40 A/g, respectively, and good long-term cycling stability (only 1.2% loss of its initial specific capacitance after 1000 cycles). These results suggest that such MnO2/ZTO/CF hybrid composite architecture is very promising for next generation high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Single crystalline Ca2B2O5·H2O (CBOH) nanobelts were synthesized for the first time using a facile catalyst-free hydrothermal method at low temperature. After being annealed at 400 °C for 10 h, the CBOH nanobelts transformed into curve-shaped Ca2B2O5(CBO) nanogrooves with ordered stacking fault arrays along the [1̅10] direction. The single crystalline CBOH nanobelts and the stacking faulted CBO nanogrooves provided a unique platform for investigating the effects of hydrated H2O and stacking faults on the mechanical properties of nanomaterials. Nanoindentation tests were performed directly on individual CBOH nanobelts and CBO nanogrooves to probe their mechanical properties. It was found that the CBOH nanobelts, with the presence of hydrated H2O, achieved 28.7% increase in elastic modulus, whereas the stacking faulted CBO nanogrooves, with the absence of hydrated H2O, exhibited 99% loss in elastic modulus, compared to bulk CBO. [ABSTRACT FROM AUTHOR]

Large-area single-crystalline vanadium dioxide nanoflakes were first fabricated via a thermal reduction method in a tube furnace. The sample was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that VO2 nanoflakes are single-crystalline with a monoclinic structure. The VO2 nanoflakes have a width of 200-300 nm, a thickness of 50-100 nm, and a length up to 1-2 üm. It is found that single-crystalline VO2 nanoflakes show a novel and complicated 5-7-step Li-storage behavior for an insertion amount of <0.6 mol lithium per mol of VO2. [ABSTRACT FROM AUTHOR]