Three-dimensional AlN microroses and their enhanced photoluminescence properties

Novel three-dimensional AlN microroses, for the first time, have been synthesized via direct reaction between Al and N2 in arc plasma without any catalyst and template.<br /

One-step synthesis of AlN branched nanostructures by an improved DC arc discharge plasma method

Aluminium nitride (AlN) branched nanostructures with tree shapes and sea urchin shapes are synthesized via a one-step improved DC arc discharge plasma method without any catalyst and template. The branched nanostructures with tree shapes and sea urchin shapes can be easily controlled by the location of collection. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies show that the branches of tree shaped nanostructures grow in a sequence of nanowires, nanomultipeds and nanocombs. The growth mechanisms of these branched nanostructures are discussed in detail. The optical properties of AlN branched nanostructures with tree shapes and sea urchin shapes are investigated

AlN nanostructures : tunable architectures and optical properties

Novel AlN nanostructures with tunable building units of the architectures have been successfully synthesized without any catalyst or template; the subsequent photoluminescence (PL) indicates that the optical properties of the AlN nanostructures can be adjusted by tuning the architectures.<br /

Unprecedented strength in pure iron via high-pressure induced nanotwinned martensite

Martensitic transformation can easily induce a maximum hardness value of 800–900 HV (Vickers hardness) for steels with carbon contents of 0.6 wt.% and above. However, the occurrence of martensitic transformation in pure iron requires exceptionally high cooling rates (105–106°C/s), and the maximum achievable hardness is only about 150 HV. Here we report an extreme hardness of 830 HV in pure iron obtained through high pressure induced martensitic transformation at a rather slow cooling rate of just 10°C/s. This unprecedented strength originates from the formation of twin-related martensitic laths with an average thickness of 3.8 nm

Propofol attenuates hypoxia-induced inflammation and apoptosis in rat pheochromocytoma cell line PC12

Objective To investigate whether propofol inhibits the expression of miR-141-3p and reduces the molecular mechanism of hypoxia-induced inflammation and apoptosis of pheochromocytoma cell line PC12. Methods PC12 cells were divided into control group, hypoxia group, (5, 10, 20)μmol/L propofol+hypoxia group, anti-miR-con+hypoxia group, anti-miR-141-3p+hypoxia group, miR-con+20 μmol/L propofol+hypoxia group, miR-141-3p+20 μmol/L propofol+hypoxia group. Flow cytometry was used to detect the apoptosis of PC12 cells; Western blot was employed to determine the expression of activated cleaved caspase-3 (cleaved caspase-3) protein, and the kits were implemented to monitor malondialdehyde (MDA) content and superoxide dismutase (SOD) activity; Reactive oxygen species fluorescent probe DCFH-DA method to determine reactive oxygen species (ROS) content; ELISA kits to assay tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 content, RT-qPCR to detect the expression of miR-141-3p. Results Compared with the control group, the apoptosis rate, cleaved caspase-3 protein expression level, MDA, ROS, TNF-α, IL-1β, IL-6 content and miR-141-3p expression of PC12 cells in hypoxia group were all increased, while SOD activity weakened (PPPPConclusions Propofol can alleviate the inflammatory response, oxidative stress and apoptosis of PC12 cells induced by hypoxia by inhibiting the expression of miR-141-3p

Exploring the coordination change of vanadium and structure transformation of metavanadate MgV2O6 under high pressure

Raman spectroscopy, synchrotron angle-dispersive X-ray diffraction (ADXRD), first-principles calculations, and electrical resistivity measurements were carried out under high pressure to investigate the structural stability and electrical transport properties of metavanadate MgV2O6. The results have revealed the coordination change of vanadium ions (from 5+1 to 6) at around 4?GPa. In addition, a pressure-induced structure transformation from the C2/m phase to the C2 phase in MgV2O6 was detected above 20?GPa, and both phases coexisted up to the highest pressure. This structural phase transition was induced by the enhanced distortions of MgO6 octahedra and VO6 octahedra under high pressure. Furthermore, the electrical resistivity decreased with pressure but exhibited different slope for these two phases, indicating that the pressure-induced structural phase transitions of MgV2O6 was also accompanied by the obvious changes in its electrical transport behavior

Carrier-Concentration-Dependent Transport and Thermoelectric Properties of PbTe Doped with Sb 2 Te 3

The conversion of heat to electricity by thermoelectric (TE) devices may play a key role in the future for energy production and utilization. Lead telluride (PbTe) is one of the best TE materials used for TE generator in the medium temperature. In this report, the transport and TE properties of PbTe doped with antimony telluride (Sb 2 Te 3 ), which has been used to optimize the carrier concentration for improved TE performance, have been studied. The scattering factor is estimated from the temperature-dependent Hall mobility and the results indicate that the scattering mechanism is changed from an ionized impurity scattering to the interaction between an acoustical and an optical phonon scattering as carrier concentration decreases and the temperature increases. The thermal conductivities for all the samples exhibit linearly dependence with reciprocal temperature and the slope increases with the carrier concentration increasing. The effective maximum power P max for PbTe samples increases with an increase of carrier concentration when the temperature gradient is over 400 K and is comparable to the functional gradient materials with the same carrier concentration. This result indicates that high TE performance has been achieved in PbTe with Sb 2 Te 3 as dopants

Pressure effects on grain boundary, electrical and vibrational properties of the polycrystalline BaTeO

The evolutions of alternate current (AC) impedance spectra, direct current (DC) resistivity and Raman spectra in polycrystalline BaTeO3 have been investigated at high pressures. The abrupt changes observed in electrical transport measurements at 12.73 GPa indicated a kind of phase transition, which was confirmed to be related to the structural phase transition by high-pressure Raman scattering experiments. From the impedance spectra, both grain resistance and grain boundary resistance decreased with increasing pressure, and two clear discontinuities occurred at 12.73 GPa and 17.47 GPa, respectively. After the transition, the contribution to the total resistance by the grain boundary effect dramatically declined and the grain resistance began to play a dominant role. Besides, the electric polarization process was changed due to the phase transition, and it led to a significant rise of the relaxation frequency. From the decompression impedance spectra, it could be clearly seen that the phase transition was irreversible, and it was probably attributed to the irreversible change of the grain boundary for the two different crystal structures. By varying the temperature, the transport behaviour at high pressure was still of semiconductor type but with different slopes for the ambient and high-pressure phases. High-pressure Raman measurements revealed an irreversible structural phase transition occurring above 15 GPa, and the results were consistent with the observed changes of the electrical properties at high pressures