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Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy, was investigated in 0.6 M NaCl solution and 0.6 M Na2SO4 solution by scanning electron microscopy (SEM) observations, scanning Kelvin probe force microscopy (SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na2SO4 solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na2SO4 solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.

As a promising energy storage system, the lithium-ion capacitor (LIC) shows tremendous potential for energy storage devices with high energy density and power density. However, limited by the poor rate performance of the anode and insufficient capacity of the cathode, its performance needs further improvement. Herein, graphene/soft carbon (G/SC) composites and graphene/activated carbon (G/AC) composites are prepared via a fast self-propagating high-temperature synthesis (SHS) process that can combine the advantages of graphene and carbon materials. For the anode, graphene enriches the reaction interface of soft carbon (SC) and ameliorates the electrochemical reaction kinetics. Therefore, G/SC exhibits superior rate capability (200 mA h g−1 at 4 A g−1) together with a high specific capacity of 360 mA h g−1 at 0.1 A g−1. Meanwhile, due to the excellent graphene network, G/AC exhibits a greatly enhanced conductivity of 2941 S m−1 and an excellent capacity retention of 84% at 10 A g−1. The LIC based on G/SC and G/AC shows a high energy density of 151 W h kg−1 and a high power density of 18.9 kW kg−1. Moreover, G/SC is synthesized on a large scale and assembled into a large-capacity LIC pouch cell (1170 F or 650 mA h), which shows an excellent energy density of 31.5 W h kg−1 (based on the total mass of the device) and remarkable cycling performance (93.8% capacity retention after 10 000 cycles at 50C). This work provides a general and effective protocol for ultrafast manufacturing of graphene-based carbon materials toward high-performance lithium-ion capacitors.

Novel hollow structure based on CuO modified V2O5 nano-string of pearls (V2O5/CuO NSPs) were synthesized via electrospinning technique. The achieved V2O5/CuO NSPs exhibit interesting shapes of string of pearls, endowed with transparent and hollow structure under TEM observation. The V2O5/CuO NSPs sensors demonstrated that the sensitivity (Ra/Rg = 8.8 at 500 ppm) towards acetone was 3.2 times as high as that of pristine V2O5 nanofibers (NFs) (Ra/Rg = 2.5 at 500 ppm) at 440 °C. The improved sensitivity may be ascribed to the formation of V2O5/CuO p-n heterojunctions at the interfaces, which elevates the barrier height and enlarges depleted electron region.

The effect of austempering temperature on the microstructure of ausferrite in austempered ductile iron was investigated. The results show that the grain sizes of retained austenite and acicular bai...

CuInxGa1−xSe2 (CIGS) nanowires were synthesized for the first time through an in situ cation exchange reaction by using CuInSe2 (CIS) nanowires as a template material and Ga-OLA complexes as the Ga source. These CIGS nanowires maintain nearly the same morphology as CIS nanowires, and the Ga/In ratio can be controlled through adjusting the concentration of Ga-OLA complexes. The characteristics of adjustable band gap and highly effective light-absorbances have been achieved for these CIGS nanowires. The light-absorbing layer in photovoltaic devices (PVs) can be assembled by employing CIGS nanowires as a solar-energy material for enhancing the photovoltaic response. The highest power conversion efficiency of solar thin film semiconductors is more than 20%, achieved by the Cu(InxGa1−x)Se2 (CIGS) thin-film solar cells. Therefore, these CIGS nanowires have a great potential to be utilized as light absorber materials for high efficiency single nanowire solar cells and to generate bulk heterojunction devices.

Taurine (2-aminoethanesulfonic acid) is a free amino acid found abundantly in mammalian tissues. Increasing evidence suggests that taurine plays a role in the maintenance of skeletal muscle function and increase of exercise capacity. Most energy drinks contain this amino acid; however, there is insufficient research on the effects of long-term, low-dose supplementation of taurine. In this study, we investigated the effects of long-term administration of taurine at low doses on aging in rodents. In Experiment 1, we examined age-related changes in aging Sprague–Dawley (SD) rats (32–92 weeks old) that O2 consumption and spontaneous activity decreased significantly with aging. In Experiment 2, we examined the effects of long-term (21-week) administration of taurine on healthy aging SD rats. SD rats were stabilized for 32–34 weeks and divided into three groups, administrated water (control), 0.5% taurine (25 mg/kg body weight (BW)/day), or 1% taurine (50 mg/kg BW/day) from age 34 to 56 weeks (5 days/week, 5 mL/kg BW). Our findings suggest that long-term administration of taurine at relatively low dose could attenuate the age-related decline in O2 consumption and spontaneous locomotor activity. Upon intestinal absorption, taurine might modulate age-related changes in respiratory metabolism and skeletal muscle function via peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), succinate dehydrogenase (SDH), cytochrome c (Cycs), myocyte enhancer factor 2A (MEF2A), glucose transporter 4 (GLUT4), and myoglobin, which are regulated by the activation of AMP-activated protein kinase (AMPK). This article examines the mechanism underlying the effects of taurine on age-related changes, which may have potential clinical implications.

The ZG40Cr20Ni20Alx (x = 0, 1.76, 3.45, and 5.34) heat-resistant steel has been newly developed on the basis of HK40 steel for aggressive oxidizing environments. The results reveal that the Al greatly enhances the oxidation resistance of ZG40Cr20Ni20 steel at high temperatures. The mass gain of ZG40Cr20Ni20 upon oxidation at 1100 &deg, C for 480 h is up to 103.6 mg/cm2, while the values for the steels containing 1.76 and 3.45 wt% Al are sharply decreased to 6.1 and 5.4 mg/cm2, respectively. Both of their matrix phases are still austenite, which is the same as that of ZG40Cr20Ni20. Their FeCr2O4 spinel oxide scales appear to be more stable under high oxygen partial pressure than that of ZG40Cr20Ni20, and the continuous Cr2O3 film appears between their matrix and spinel oxide. As for the steel with 5.34 wt% Al, the mass gain is only 1.1 mg/cm2. Its matrix is compared to those of austenite and ferrite, and the oxide scale is continuous Al2O3.

Based on density functional calculations, Mo and P co-doped Ba5Ta4O15 compared with their mono-doping was studied for splitting water. The results showed that Mo–P co-doping significantly reduced the energy gap of Ba5Ta4O15 from 4.05 eV to 2.15 eV, being almost the optimum value for utilizing solar energy as much as possible. The top of valence band and the bottom of conduction band are both compatible with the oxidation-reduction potentials of water. More importantly, Mo–P co-doping prevents the filled spin-down states of Mo and the empty spin-down states of P from arising due to the charge compensation of Mo–P pairs. We propose that Mo–P co-doped Ba5Ta4O15 is one of the most promising photocatalyst candidates for solar water splitting.

CuIn

We report on the synthesis of CuInTe2 nanoparticles and their function in photovoltaic equipment, such as solar cells. Under certain synthesis conditions, the CuInTe2 nanocrystals form shape with nanocrystals, nanorods or nanocubes. It was found that CuTe nanocrystals could be converted to CuInTe2 by addition of an In reactant. CuInTe2 nanorods were synthesized using this method.

We report a novel synthesis of monodisperse samples of copper telluride with crystallinity and stoichiometry corresponding to forms of rickardite, Cu 3− x Te 2 ( x < 1). This synthesis makes use of a ligand balanced reaction to allow control over shape and size by varying the relative and absolute concentration of oleylamine to stearic acid. The rickardite samples presented here display size dependent plasmon peaks in the near infrared and direct energy band gaps between 1.7 and 2.3 eV. As such they may find utility in photovoltaic, thermoelectric or as novel optical materials for study of surface plasmons.

We have developed a Co-free equiatomic FeCrNiMn alloy with high yield strength and elongation. The novel networks composed of ultrafine precipitates were introduced into the cast FeCrNiMn alloy by annealing. In addition, the coarse dendrites formed during casting are dramatically reduced by annealing. The yield strength and elongation of newly-developed medium entropy alloy are 398 MPa and 60.2% at room temperature, which are superior to the performance of expensive FeCoNiCrMn high entropy alloys. The excellent mechanical properties benefit from the newly-formed networks composed of ultrafine precipitates and the sharp decrease of coarse dendrites during annealing.

Based on the first principles with the Tran–Blaha modified Becke–Johnson potential, we have adjusted the band edges of NaTaO3 by doping to improve the photocatalytic efficiency of solar water splitting. By analyzing the band structures and the band-edge positions of passivated co-doped NaTaO3, we have found that the band gap of P–Mo co-doped NaTaO3 is narrowed to 2.04 eV, being the optimal value for the efficient solar splitting of water, and its band edges straddle the water redox potential levels. As compared to mono-doping with either anions (N or P) or cations (Cr, Mo, or W), the passivated co-doping can prevent the partially filled states from appearing at the band edges, resulting in a high photocatalytic efficiency. Hence we propose that passivated P–Mo co-doped NaTaO3 is an excellent candidate for efficient hydrogen production through water splitting under visible light. The design principle for tuning the band edges should be applicable to other tantalate and niobate semiconductors with wide band gaps.

The search for a semiconductor with an optimal band gap of about 2.0 eV as a photocatalyst for efficient water splitting using solar energy is one of the noble missions of material science. Here, we prove that single- and few-layer ZrS 2 have an optimal band gap of about 2.0 eV and enough potential differences to drive the hydrogen and oxygen evolution reaction based on first-principles calculation with the Tran-Blaha modified Becke–Johnson potential. Therefore, they can be used as efficient photocatalysts for solar water splitting. Moreover, we take single-layer ZrS 2 as an example of tuning the band edge positions by strain in order to further improve the efficiency of solar energy conversion. The results show that a tensile uniaxial strain of 4% can minimize the difference between the conduction band potential difference and the valence band potential difference and, thus, maximize the photocatalytic efficiency of monolayer ZrS 2 .

Based on first principles with the Tran-Blaha modified Becke-Johnson potential, pure and doped Ba5Nb4O15 have been investigated as highly efficient photocatalysts for solar water splitting. The results showed that the calculated band gap of Ba5Nb4O15 is improved to 3.81 eV by the new potential. Mono-doping with either anion (N, P) or cation (Mo) creates some partially occupied states at the band edges of Ba5Nb4O15. N–Mo co-doping and P–Mo co-doping can prevent the partially filled states from appearing at band edges and hence enhance the photocatalytic efficiency. The band edges of the co-doped systems still satisfy the requirements for spontaneous water splitting. More importantly, the band gap of P–Mo co-doped system is sharply reduced to 2.31 eV, being in ideal visible light region. The defect formation energy calculations show that P–Mo co-doped Ba5Nb4O15 is energetically favorable under O-rich and Nb-poor conditions. These show that P–Mo co-doped Ba5Nb4O15 has high efficiency for water splitting under visible light.

The spatial and temporal dependence of population dynamics caused by ultrafast π laser pulses are studied by Maxwell-Bloch equations in terahertz quantum cascade lasers with and without propagation effects. It is shown that the presence of propagation effects could decrease the flopping of population inversion and affect the oscillation intensity in recovery process. Due to the modification of total macroscopic nonlinear polarization and many-body items, local field varies not only with electron doping concentration but also with period position, which also reflected in the evolution of population dynamics.

Branched CuInSe 2 nanowires (NWs) are successfully synthesized by one-pot method for making secondary bismuth nanoparticles to attach onto the CuInSe 2 NWs stem for inducing the secondary branch growth by solution-liquid-solid (SLS). The branched CuInSe 2 NWs were measured in order to reveal its viability for PV device fabrication and application for the light-absorbing material in solar cells.

The hydrogen-induced cracking (HIC) and blistering behaviour of A537 steel was investigated by electrochemical hydrogen permeation measurements, electrochemical hydrogen-charging tests, and surface characterisation techniques. The results indicate that at ambient temperatures the diffusivity of hydrogen in A537 steel varies along three perpendicular directions. The diffusivity of hydrogen along the through-surface ( S ) direction was observed to be lower than that along each of the other two directions. The hydrogen concentration of A537 steel increased with increasing charging current density, which promoted the HIC susceptibility of the A537 steel. HIC initiated primarily at the interface of ferritic/pearlitic bands and nucleated at non-metallic inclusions in the A537 steel.

The microstructure of austempered ductile iron was investigated by electron backscatter diffraction technique. The results show that the orientation relationship between acicular bainitic ferrite and austenite is Greninger–Troiano relationship. A single austenite grain is divided into four packets and each packet contains six variants that share a {011}α (i.e., {111}γ) plane. When two γ grains are twinned, the twins share a {111}γ plane and have seven packets. The adjacent acicular bainitic ferrite plates (or laths) sharing a 〈 001 〉 γ axis have small misorientation of about 5.7°. The adjacent acicular bainitic ferrite plates (or laths) not sharing a 〈 001 〉 γ axis have two high misorientation angles of ~54.3° and ~60.0°. Further, the low angle boundary to high angle boundary ratio is far less than the ratio of the variant pairs with small misorientation to the ones with large misorientation. This work is available for structures obtained as a consequence of the heat treatment of austempering.

The electronic structures of pure, mono-doped (either Mo or N), and co-doped (Mo and N) SrTiO3 are calculated by first principles with the Tran-Blaha modified Becke–Johnson potential. Results show that the calculated band gap of SrTiO3 is improved from 1.87 to 3.27 eV by this new method, being in good agreement with the experimental value. Mo and N co-doping can prevent not only the partially occupied states from appearing at the band edge but also the two N atoms coupling. Therefore, the high activity of photocatalysis remains and the band edges are compatible with the redox potentials for water splitting. More importantly, the band gap of the most stable co-doped configuration is sharply narrowed to 2.07 eV. The defect formation energy calculations indicate that the co-doped systems are energetically favorable in Ti-poor and O-rich environments. These show that Mo and N co-doped SrTiO3 should be a good candidate for water splitting using sunlight.

The decrease of Currie temperature in milled MgB 2 could be caused by some native point defects such as vacancies, antisites, and interstitials. In order to clarify it, the formation energies of the native point defects in MgB 2 were examined, and the influence of the stable defects on its electronic structure was investigated by first-principles calculation. It was found that the B interstitials and the B vacancies have the lowest formation energies under Mg-rich (Mg:B > 1:2) and Mg-poor (Mg:B > 1:2) conditions, respectively, compared to other native point defects. The density of states at the Fermi level for MgB 2 with and without point defects is mainly comprised of the B’s p orbital. Under Mg-poor conditions, the partial density of states (at the Fermi level) of the B’s p orbital for MgB 2 with B interstitials reduces with the increase of its concentration. Under Mg-rich conditions, the B vacancies first increase and then decrease the partial density of states at the Fermi level of the B’s p orbital as its content increases.

The electronic structures of pure, I doped, Mn doped, and I and Mn co-doped BiOCl are calculated by the first-principles method with the Tran–Blaha modification of the Becke–Johnson potential. The calculated band gaps of the pure as well as doped BiOCl are greatly improved compared with the results calculated using the generalized gradient approximation. Specifically, the calculated band gap of pure BiOCl is improved to 3.40 eV, being in good agreement with the experimental value of 3.46 eV. The results also show that the band gap of I and Mn co-doped BiOCl is the narrowest (2.21 eV) among the researched systems and has a strong ability for oxidation. This indicates that I and Mn co-doped BiOCl is a potential material for visible light photocatalysis.

The effects of mono-doping (N, C, La, and Ce) and co-doping (N–La, C–Ce, and N–Ce–N) on the electronic structure of SrTiO3 are studied by the first-principles method. The results show that some partially occupied states acting as recombination centers appear in the mono-doped systems and thereby suppress their photocatalytic activity. The co-doping can inhibit the partially occupied states and thus keep the high activity of photocatalysis. Further, the (N–Ce–N) co-doping can significantly narrow the band gap of SrTiO3 to make it fall in the visible light region while keeping the match of the band edges with the redox potential for water splitting. The high activity and narrowed band gap show that the (N–Ce–N) co-doped SrTiO3 is a good candidate for water splitting under visible light irradiation.

We report on the synthesis of CuInTe2 nanoparticles and their function in photovoltaic equipment, such as solar cells. Under certain synthesis conditions, the CuInTe2 nanocrystals form shape with nanocrystals, nanorods or nanocubes. It was found that CuTe nanocrystals could be converted to CuInTe2 by addition of an In reactant. CuInTe2 nanorods were synthesized using this method.

MgB 2 bulks were fabricated using milled precursor powders with aniline dopant and the low purity B was used as a starting material. The flux pinning, B c2 and magnetic J c of MgB 2 are greatly enhanced by aniline doping. The magnetic J c value of MgB 2 sample with 3 wt% aniline is 9.5 × 10 3 A cm −2 at 5 K and 6 T, 13 times larger than that of the pure one. Furthermore, the liquid aniline can avoid the agglomeration of precursor powder during high energy milling. Long time ball milling can further improve the electromagnetic properties of aniline doped MgB 2 samples. At 5 K and 6 T, the J c of the 80 h 3 wt% sample is up to 5.5 × 10 4 A cm −2 , 6 times larger than that of the 0.5 h 3 wt% one and 77 times larger than that of the 0.5 h pure one (the “80 h” and “0.5 h” refer to ball milling times). These results indicate that the liquid C-containing dopant combined with high energy milling may be an effective way to achieve the excellent electromagnetic properties of MgB 2 .

The doping effect of different carbon source on the properties of MgB 2 tapes was compared using three typical dopants, nano-C, C 60 , and C 9 H 11 NO. It is found that C 60 doped samples showed the highest carbon substitution ratio and resistivity, with the lowest T c . For the nano-C doped samples, T c did not drop so significant, which is only 2 K lower than that of the pure ones. Compared to C 60 and C 9 H 11 NO doped samples, the nano-C doped samples show a lower J c value at 5 K. On the other hand, the C 9 H 11 NO doped samples show a high J c value at both 5 K and 20 K. This is a representative demonstration to the complex affecting factors on the J c – H property of MgB 2 tapes. Detailed mechanism for the property difference in MgB 2 induced by different chemical doping is discussed based on the systematically examined results.

The electromagnetic parameters and microwave absorbing properties of paraffin and polymer composites filled with glass-coated Fe69Co10Si8B13 amorphous microwire (GCFAW) were investigated. The results show that the microwire filling ratio and annealing temperature have no obvious influence on the complex permeability, while they exhibit significant effect on the complex permittivity. The complex permittivity increases remarkably with the increase of microwire filling ratio, and decreases sharply with increasing the annealing temperature. With the increase of microwire filling ratio and absorber thickness, the minimum reflection loss decreases firstly and then increases, and shifts towards lower frequency region. For the paraffin composite with GCFAW filling ratio of 15% and thickness of 1.4 mm, the minimum reflection loss is −28.5 dB and the frequency bandwidth less than −10 dB is 2.9 GHz. When the microwire filling ratio and the thickness of paraffin composite are invariant, the frequency of minimum reflection loss shifts towards higher region with increasing the annealing temperature. The change trend of measured reflection loss of polymer composite is consistent with that of calculation reflection loss of paraffin composite, but the minimum reflection loss increases a little and shifts towards lower frequency. As the microwire filling ratio is 15%, the reflection loss of polymer composite exhibits two extreme values.

Fe-clad BaxK1-xFe2As2 superconducting tapes were fabricated by the ex situ powder-in-tube method combined with a short high-temperature annealing technique. The effect of annealing time and different dopants on the transport properties of the BaxK1-xFe2As2 tapes were systematically studied. By co-doping with Ag and Pb, the transport critical current density Jc of BaxK1-xFe2As2 tapes was significantly improved in whole field region and the highest transport Jc was up to 1.4x10^4 A/cm^2 (Ic=100 A) at 4.2K in self field. It is proposed that the superior Jc in the co-doped samples are due to the combine effect of Pb doping at low fields and Ag doping at high fields., Comment: 22 pages, 7 figures, to be published in Supercond. Sci. Technol

SmFeAsO1-xFx tapes were prepared using three kinds of starting materials. It shows that the starting materials have an obvious effect on the impurity phases in final superconducting tapes. Compared with the other samples, the samples fabricated by SmAs, FeO, Fe2As, and SmF3 have the smallest arsenide impurity phase and voids. As a result, these samples possess much denser structure and better grain connectivity. Moreover, among the three kinds of samples fabricated in this work, this kind of sample has the highest zero-resistivity temperature ~40 K and largest critical current density ~4600 A/cm^2 in self-field at 4.2 K. This is the highest Jc values reported so far for SmFeAsO1-xFx wires and tapes., Comment: 15 pages, 4 figures

The effects of different substitutions on (Pb0.5Cd0.5)Sr2(Y0.5Ca0.5)Cu2O7 have been investigated. For (Pb0.5Cd0.5)Sr2(Y1-xCax)Cu2O7 (0.0 less-than-or-equal-to x less-than-or-equal-to 1.0), an anomalous variation of lattice constants with x is observed, and a sharp increase in T(c) occurs when x increases from 0.4 to 0.5. For (Pb0.5Cd0.5)Sr2-y(Y0.5+yCa0.5)Cu2O, (-0.2 less-than-or-equal-to y less-than-or-equal-to 0.3), as yttrium content increases the phase purity increases, and both the a and c lattice constants decrease. The superconducting properties deteriorate as y deviates from 0.0. For (Pb0.5Cd0.5)Sr2-z(Y0.5Ca0.5+z)Cu2O7 (-0.2 less-than-or-equal-to z less-than-or-equal-to 0.2), both the a and c lattice constants decrease as z increases. The superconducting properties deteriorate as z deviates from 0.0, although the effect is very small. From the T(c) results obtained in the three series, the conclusion can be reached that the yttrium content in the (Y, Ca) sites is a key factor in controlling the superconducting properties of the (Pb, Cd)- 1 212 phase.

We report the realization of grain alignment in Sn-added Sr1-xKxFe2As2 superconducting tapes prepared by ex-situ powder-in-tube method. At 4.2 K, high transport critical current densities Jc of 2.5x10^4 A/cm^2 (Ic = 180 A) in self-field and 3.5x10^3 A/cm^2 (Ic = 25.5 A) in 10 T have been measured. These values are the highest ever reported so far for Fe-based superconducting wires and tapes. We believe the superior Jc in our tape samples are due to well textured grains and strengthened intergrain coupling achieved by Sn addition. Our results demonstrated an encouraging prospect for application of iron based superconductors., 14 pages, 4 figures

Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation.