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SnO2/TiO2 type II heterojunctions are often introduced to enhance the separation efficiency of photogenerated carriers in photoelectrochemical electrodes, while most of these heterojunctions are of core–shell structure, which often limits the synergistic effect from the two components. In this work, dissymmetric SnO2/TiO2 side-by-side bi-component nanofibers (SBNFs) with tunable composition ratios have been prepared by a novel needleless electrospinning technique with two V-shape connected conductive channels (V-channel electrospinning). Results show that this V-channel electrospinning technique is more stable, controllable and tunable for the large-scale preparation of SBNF materials compared to the traditional electrospinning using two side-by-side metal needles. And these SnO2/TiO2 SBNFs are dissymmetric and comprised of a tiny SnO2 NF (tunable diameter within 20–80 nm) and a Sn-doped TiO2 NF (diameter of ~ 250 nm) with a side-by-side structure. Moreover, the dye-sensitized solar cells (DSSCs) based these dissymmetric SnO2/TiO2 SBNFs show the maximum power conversion efficiency (PCE) of 8.3%, which is 2.59 times that of the ones based on the TiO2 NFs. Series of analyses indicate that the enhancements in PCE could mainly be due to the improved electron transport via SnO2 NFs and the enhanced carrier separation via dissymmetric SnO2/TiO2 heterojunction interface. This research will give some new insight in the preparation of SBNFs for high-performance photoelectrochemical devices.

The formability of magnesium alloys at ambient temperature can be enhanced by alloying additions such as Ca and RE elements, which is ascribed to the weakened basal texture. To produce magnesium alloy sheets with excellent comprehensive performance, the evolution of texture characterization during fabrication process and subsequent effect of texture on mechanical properties are vital controlling factors. In this investigation, three experimental Mg-3Al series alloys were hot rolled and annealed to sheets with 1 mm thickness. The microstructure evolution during rolling and annealing process was investigated. Furthermore, the influence of texture on tensile properties along different tensile directions was also studied. The results show that weakened basal texture and refined grains were achieved with the co-addition of Ca and RE element. However, strengthening of mechanical properties wasn't obtained. During hot rolling process, microstructure was refined, second phase particles broken, and basal texture was increased. While basal texture was weakened during annealing process. Recrystallization behavior influenced by formation of second phase was dominated to attenuate basal texture. Tensile deformation behavior was controlled by basal slip and followed Schmid factor criterion. Moreover, the weakened basal texture and activation of non-basal slips during hot rolling process can contribute to diminish the anisotropy of tensile properties.

The stability and reliability of electrical ohmic contacts are the key to the stable operation of silicon carbide power electronic devices in extreme environments. Firstly, the current research status and common problems of SiC ohmic contacts has been analyzed. Secondly, a carrier model for the ohmic contact between metals and SiC based on the tunneling effect is established. By increasing the doping concentration of the substrate SiC, the Schottky barrier width can be reduced, which is more conducive to the formation of ohmic contacts. Thirdly, 200nm thick Ni metal layer was deposited on 4H-SiC substrate with a doping concentration of NA=2e19cm-3. Finally, the effect of high-temperature thermal annealing temperature on metal ohmic contact is studied and results show that Ni can form ohmic contact with SiC when the annealing temperature exceeds 800°C. Scanning electron microscope and atomic force microscope are used to observe the contact surface. After high-temperature thermal annealing, the electrical properties are guaranteed, but metals indicate defects such as cluster precipitation. Therefore, it is possible to prevent the contact layer metal from being damaged by adding other covering metals.

A large and tunable lateral shift in a prism coupling system with a superconducting YBa2Cu3O7 film is theoretically analyzed. The dip of the reflectivity and magnitude of the lateral shift can be controlled by the temperature of the superconducting film. The sign of the lateral shift can be determined by the thickness of the superconducting film. The position of the minimum reflection and maximum Goos–Hanchen shift can be conveniently adjusted by the thickness of the dielectric layer and incident light frequency. The largest shift, as high as 1550 times the free space wavelength, is achieved for the incident light frequency $$\omega = 98$$ THz. The numerical calculation results from the Gaussian beam are in accordance with the theoretical results.

Molecular dynamics (MD) simulations were applied to study the fundamental mechanism of nanoscale grinding with a modeled tool trajectory of straight lines. Nevertheless, these models ignore curvature changes of actual tool paths, which need optimization to facilitate understanding of the underlying science of the machining processes. In this work, a three-dimensional MD model considering the effect of tool paths was employed to investigate distributions of stresses including hydrostatic stress, von Mises stress, normal and shear stresses during atomic grinding. Simulation results showed that average values of the stresses are greatly influenced by the radius of the tool trajectory and the grinding depth. Besides the averaged stresses, plane stress distribution was also analyzed, which was obtained by intercepting stresses on the internal planes of the workpiece. For the case of a grinding depth of 25 &Aring, and an arc radius 40 &Aring, snapshots of the stresses on the X&ndash, Y, X&ndash, Z and Y&ndash, Z planes showed internal stress concentration. The results show that phase transformation occurred from &alpha, silicon to &beta, silicon in the region with hydrostatic stress over 8 GPa. Moreover, lateral snapshots of the three-dimensional stress distribution are comprehensively discussed. It can be deduced from MD simulations of stress distribution in monocrystalline silicon with the designed new model that a curved tool trajectory leads to asymmetric distribution and concentration of stress during atomic-scale grinding. The analysis of stress distribution with varying curve geometries and cutting depths can aid fundamental mechanism development in nanomanufacturing and provide theoretical support for ultraprecision grinding.

The absorption properties in heterostructure with the hexagonal boron nitride crystal are investigated theoretically. It is shown to absorb roughly 90% in reststrahlen upper-frequency band at normal incidence. However, the maximum absorption is only 30% in reststrahlen lower-frequency band. The magnetic fields are found to be strongly localized between the interface of the dielectric and hBN crystals with evanescent light wave in the both reststrahlen bands. The effects of the thickness of dielectric on the absorption are also specifically explored.

Effect of various Ca content on microstructure and fracture toughness of extruded Mg-2Zn was investigated in this paper. The experimental results show that Ca addition (0.2 wt% Ca, 0.5 wt% Ca) gradually refines the recrystallized grains of Mg-2Zn, changes the type, size and distribution of precipitates in Mg-2Zn and also strengthens their (0002) textures. On the other hand, as Ca content increases, the yield and tensile strength of Mg-2Zn gradually increases but their total elongation decreases. Moreover, the plane strain fracture toughness (evaluated by KIC value) of extruded Mg-2Zn is improved and ductile fracturing gradually becomes dominant with increasing Ca addition. The grain refinement of Mg-2Zn with increasing Ca addition is mainly attributed to the restraining effect of Ca-containing precipitates on the growth of the dynamic recrystallized (DRXed) grains during extrusion process. And the enhancement of fracture toughness of extruded Mg-2Zn due to Ca addition mainly results from the grain refinement effect which activates the non-basal slip and decreases the fraction of deformation twins.

Bimetallic noble metal nanocrystals have been widely applied in many fields, which generally are synthesized by the wet-chemistry reduction method. This work presents a purposely designed atoms diffusion induced phase engineering of PtAu alloy nanocrystals on platy Au substrate (PtAu-on-Au nanostructures) through simple hydrothermal treatment. Benefitting from the synergistic effects of component and structure, PtAu-on-Au nanostructures remarkably enhance the dehydrogenation pathway of the formic acid oxidation reaction (FAOR), and thus exhibit much higher FAOR activity and durability compared with Pt nanocrystals on platy Au substrate (Pt-on-Au nanostructures) and commercial Pd black due to an excellent stability of platy Au substrate and a high oxidation resistance of PtAu alloy nanocrystals. The atoms diffusion-induced phase engineering demonstrated in this work builds a bridge between the traditional metallurgy and modern nanotechnologies, which also provides some useful insights in developing noble metals based alloyed nanostructures for the energy and environmental applications.

A broadband absorber which was proposed by one dimensional photonic crystal (1DPC) containing graphene-based hyperbolic metamaterials (GHMM) is theoretically investigated. For TM mode, it was demonstrated to absorb roughly 90% of all available electromagnetic waves at a 14 THz absorption bandwidth at normal incidence. The absorption bandwidth was affected by Fermi energy and thickness of dielectric layer. When the incident angle was increased, the absorption value decreased, and the absorption band had a gradual blue shift. These findings have potential applications for designing broadband optoelectronic devices at mid-infrared and THz frequency range.

Ion implantation is increasingly applied to assist machining micro/nano devices in academic research and industry. A method of heavy ions assisted light ions implantation was proposed to modify 4H-SiC for reducing difficulty in ultra-precision machining. First, a three-dimensional molecular dynamics (MD) simulation model for ion implantation into SiC surface was established. The lattice damage mechanism of SiC under implantation of different ions including H+, Cu2+, and collaboration of Cu2+ and H+was studied. Projection range of the model with collaboration of Cu2+ and H+ was the largest. Then, the workpiece after ion implantation was annealed to study residual stress. The results show that high-temperature annealing contributes to reducing residual tensile stress. Finally, a MD model with length of 1530 A along the Z-axis was built to compare with actual experiments using the same ion implantation parameters. The resulted subsurface damage values were quite close which demonstrates feasibility of the MD model. Surface morphology, cross-section of the defects, and three-dimensional ion distribution on the implanted samples surface were also observed and displayed. As demonstrated by simulation and experiments, the method of collaborative ion implantation can effectively modify surface of hard and brittle materials and bring benefits for subsequent ultra-precision machining.

SiC, as one typical 3rd generation semiconductor, has high potential to be used as the substrate for harsh environment sensors. However, the etching of this material is still challenging. Femtosecond laser has been demonstrated to have great potential in SiC etching, but the material removal mechanisms need further investigation. Herein, the two-temperature model considering carrier concentration is utilized to illustrate the microscopic mechanism of carrier concentration and temperature change in SiC caused by femtosecond laser irradiation. An 800 nm, 50 fs, 10 Hz Ti: sapphire femtosecond laser was used to process SiC in different media including air, HF and water. The ablation threshold of SiC in the three media is calculated. The highest ablation threshold (4.98 J/cm2) is obtained when the pulse number N = 50, in air. The lowest ablation threshold (0.53 J/cm2) is obtained when the pulse number N = 300, in HF. Results indicate that ablation threshold is strongly dependent on the laser pulse number and processing medium. Based on the cleavage phenomenon of SiC crystal structure observed by micro-nano characterization, the mechanism model of femtosecond laser-induced periodic structure of SiC surface based on material lattice cleavage is established, and the relationship between the intrinsic texture and the evolution of periodic structure of ablation surface is revealed. This will provide a new way to understand the ablation mechanism of femtosecond laser. In addition, the processing media has significant effect on surface roughness and chemical bond characteristics of SiC. Liquid processing media can reduce the surface roughness and avoid oxidation, which is helpful to manufacture SiC devices with specific surface requirements using femtosecond laser as an auxiliary method.

For the large-scale commercialization of direct methanol fuel cells, developing Pt-alternative anode electrocatalysts with low cost and high activity plays an important role. In this work, a one-pot hydrothermal method has been developed for the direct synthesis of the Rh nanosheets (Rh-NSs) on reduced graphene oxide (RGO). The newly prepared Rh-NSs/RGO hybrids have great electrocatalytic activity for the methanol oxidation reaction (MOR) in alkaline media, much better than single-component Rh nanoparticles (Rh-NPs) and Rh nanoparticles/RGO (Rh-NPs/RGO) hybrids, originating from the two-dimensional structure of Rh nanosheets and excellent physical/chemical property of the RGO. Very importantly, cyclic voltammetry (CV) measurements show the onset oxidation potential of the MOR at the Rh-NSs/RGO hybrids negatively shift ca. 120 mV compared to the commercial Pt/C electrocatalyst. Meanwhile, CV measurements show that the MOR current at the Rh-NSs/RGO hybrids is 3.6 times bigger than that at the commercial Pt/...

Based on the Euler-Euler method and the conservation equation, a mathematical model for describing the non-steady processes of mass transfer, transmission, heat transfer, solute transport and nonstationary process of nucleation in liquid-liquid separation of Al-Pb monotectic alloys was established. The influence of the second phase content on the solidification microstructure of Al-Pb alloy was analyzed by numerical simulation by combining the calculated temperature field and velocity field with the kinetic equation of controlling solidification microstructure evolution. The results show that the lower the second phase content is, the more uniform the temperature field distribution is, and the lower the velocity of the second phase droplets is. The average diameter and volume fraction of the second phase droplets in the Al-5wt%Pb alloy samples were lower than that in the Al-10wt%Pb alloy samples under the same conditions. It is concluded that the lower the content of the second phase, the liquid - liquid phase separation and decomposition behavior of liquid immiscible liquid in the immiscible zone are relatively slow, and the more easily the droplets of the second phase are distributed uniformly in alloy solidification structure of the matrix.

A numerical model describing the liquid-liquid phase transformation of the nucleation, the diffusional growth, Ostwald coarsening and macro-transport phenomena was established based on Euler-Euler method. The microstructure development of Al-Bi alloys in different solidification rate has been simulated by coupling the calculated temperature and velocity fields with the kinetic equation which controls the microstructure evolution. The results showed that average diameter difference of L2 phase droplets between top and bottom of samples in low cooling rate increased by 151 % than in high cooling speed and the maximum volume fraction of the droplets at the bottom of the sample in low cooling rate much higher than in high cooling rate. Analysis that the bigger cooling rate can shorten the action time which caused by gravity settling and collisions coagulation of the droplets, and then improves the macrosegregation of solidification structure in favor of uniform distribution of the solidification structure.

The solidification experiments about macrosegregation formation of the Al-10%Bi hyper monotectic alloys under gravity conditions have been carried out. The results showed that the average diameter of the Bi-rich droplets linearly increases and the number density of the Bi-rich droplets exponentially decreases with solidification time under the gravity condition. Because of gravity settling and collisions coagulation between the droplets, area fraction of Bi-rich increased rapidly in the bottom of samples during early solidification. It’s easy to form Bi-rich layer at the bottom of the sample. The analysis demonstrates that nucleation and diffusion growth of drops are the dominant factors influencing the solidification microstructure during the early solidification and the same distribution of Bi-rich in different locations of sample. As the solidification process, gravity migration and collision coagulation beginning to play the leading role, lead to the difference in the distribution of Bi-rich droplets in different locations of sample 90%e5%a2%9e%e5%a4%a7&tjType=sentence&style=&t=increases+gradually" increases gradually in the same time. It caused macrosegregation of the final solidification microstructure under the gravity condition.

After hot rolling magnesium alloy sheets exhibit an intensive basal texture, leading to its low formability at room temperature. Microalloying is an effective, practicable and economical measure to improve the comprehensive performance of magnesium alloy, especially for taking Ca and Gd as main components recently which greatly increases the room temperature formability of magnesium alloy by attenuating or tilting the basal texture. In this study some Mg-3Al alloys with Ca single and Ca-Gd combined microalloying were hot rolled at 673K and annealed at 623K for 1h. The effect of addition of Ca and Gd on microstructure, texture and tensile properties of Mg-3Al series alloy were investigated. The results showed that the single addition of Ca element can attenuate basal texture and improve room temperature formability of Mg-3Al alloy, but limitedly refine grain size. The combined addition of microalloying Ca and Gd element can significantly attenuate basal texture and improve refinement of grain size and room temperature formability of Mg-3Al alloy, also reduce the anisotropy of mechanical property. The main reason for attenuating basal texture is that the recrystallization behavior is delayed due to the secondary phase. The attenuating of basal texture and the activation of non-basal slip systems are the mechanism of the reduced anisotropy.

The resistance for pitting corrosion, passive film stability and antibacterial performance of 316L-Cu SS passivated by nitric acid solution containing certain concentration of copper sulfate, were studied by electrochemical cyclic polarization, electrochemical impedance spectroscopy (EIS) and co-culture with bacteria. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the Cu2+ ions release from 316L-Cu SS surface. XPS analysis proved that the enrichment of CuO, Cr2O3 and Cr(OH)3 on the surface of specimen could simultaneously guarantee a better corrosion resistance and stable antibacterial properties. The biocompatibility evaluation determined by RTCA assay also indicated that the 316L-Cu SS after antibacterial passivation was completely biocompatible.

Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction (MOR) on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.

Movement trajectory of diamond tool during an ultra-precision cutting may be nonlinear due to external vibrations. Hence, we investigate nanoscale cutting of monocrystalline silicon using molecular dynamics simulation when the diamond tool trajectory contains an arc segment. Surface morphology, atomic displacement, radial distribution function, coordination values, common neighbor analysis, temperature variation and distribution of von Mises stress and hydrostatic stress are studied by changing the arc radius of tool path. An optimal surface integrity for the workpieces is obtained when the arc radius is 30 A. Displacement vector analysis shows that the atoms at the initial position between the diamond tool and the workpiece have relatively large displacement. Furthermore, cutting distance has great influence on radial distribution function and atomic coordination values. Dislocation analysis indicates that the subsurface of workpiece with the arc radius of 30 A is the smoothest, while temperature analysis reveals that only the maximum temperature of this workpiece exceeds 1000 K. Finally, the stress analysis indicates that the average hydrostatic stress decreases before increasing with the arc radius. For comparison, the average von Mises stress increases gradually. In addition, peak value of the two average stresses resides at the middle and the end of the arc, respectively. The curve trajectory of the tool results in the concentration of the hydrostatic stress and the von Mises stress in the local region of workpiece subsurface.

The tunable and enhanced Goos–Hanchen (GH) shift for TM-polarized reflected beam from the graphene-based hyperbolic metamaterials (GHMM) is theoretically investigated. It is demonstrated that the lateral shift of the reflected beam can be tunable by Fermi energy and thickness of dielectric, and the largest GH shifts can be hundreds of wavelengths due to the enhanced effect by the GHMM. The minimum reflected angle (Brewster angle) moves to larger angle of incidence with the Fermi energy and thickness of dielectric increasing. Numerical simulation results for Gaussian incident beams coincide with the theoretical results from the stationary-phase method. The GH shift from the GHMM, maybe, open a new way for photoelectronic device application in future.

This article introduces an element diffusion behavior model for a titanium/steel explosive clad plate characterized by a typical curved interface during the heat-treatment process. A series of heat-treatment experiments were conducted in the temperature range from 750°C to 950°C, and the effects of heat-treatment parameters on the microstructural evolution and diffusion behavior were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and electron-probe microanalysis. Carbon atoms within the steel matrix were observed to diffuse toward the titanium matrix and to aggregate at the bonding interface at 850°C or lower; in contrast, when the temperature exceeded 850°C, the mutual diffusion of Ti and Fe occurred, along with the diffusion of C atoms, resulting in the formation of Ti–Fe intermetallics (Fe2Ti/FeTi). The diffusion distances of C, Ti, and Fe atoms increased with increasing heating temperature and/or holding time. On the basis of this diffusion behavior, a novel diffusion model was proposed. This model considers the effects of various factors, including the curvature radius of the curved interface, the diffusion coefficient, the heating temperature, and the holding time. The experimental results show good agreement with the calculated values. The proposed model could clearly provide a general prediction of the elements’ diffusion at both straight and curved interfaces.

As flame-retardant Polyacrylonitrile (PAN) fibers was one of the most important differential fibers, it was of great importance to make research on the modification of flame-retardant PAN fibers to improve its characteristics. In this present study, the flame-retardant PAN fiber with good moisture absorption and mechanical properties has been prepared treated by blending solution of sodium hydroxide and hydrazine hydrate. FTIR spectra presented that new amide and cyclization-crosslinking pyridine group band peaks appeared. X-ray diffraction showed that the crystal structure of PAN fibers has been converted from quasi-crystalline structure into partially crystallized structure after modification treatment. SEM micrographs indicated that the original longitudinal surface microgroove has changed to layered structure by surficial etchant.

Melamine formaldehyde (MF) resin and its derivatives are always considered to be an excellent flame retardant material, which has a wide application in the flame retardant fabric, thermal insulation and high temperature filter Materials etc. The melamine formaldehyde resin (MF) and polyvinyl alcohol (PVA) blend electrospinning were studied in this work. MF-PVA electrospun fiber membrane was successfully prepared, and the limit oxygen index (LOI), scanning electron microscopy (SEM), infrared spectrum (IR) and X-ray diffraction (XRD) have been used to analyze and characterize the fiber. The results show that: The blending fiber is endowed with effective flame retardant property by the amino group and triazine ring group in MF/PVA fibers, and the LOI reaches 28~31. The MF and PVA blend fiber showed best uniformity when the blending solid content ratio of MF-PVA is 1:1. MF/ PVA blend fiber has certain crystallization capacity, which influences both the mechanical properties and flexibility of blending fiber.

Melamine formaldehyde (MF) resin and its derivatives are always considered to be excellent flame retardant material, which has wide application in the flame retardant fabric, high temperature insulating filter materials, etc. However, less research on electro-spinning of melamine fiber has been reported, recently. In the study, the molar ratio, condensation polymerization temperature of formaldehyde and melamine, and the law of effect in different solid content ratio of melamine formaldehyde/polyvinyl alcohol on the electro-spinning were studied. The results showed that the best conditions for spinning were that formaldehyde and melamine molar ratio was 1:1.7, the reaction temperature was 80°C, and the MF-PVA blending solid content ratio was 1:1, meanwhile the morphology of Electron microscopy indicated the good uniformity of the fiber. The fiber presents good flame retardant property in conditions of MF-PVA blending solution viscosity 155mPa ́s, limit oxygen index 33.2%.

The catalyst with high activity, 100% selectivity and good durability is highly desirable in developing a hydrous hydrazine-based hydrogen generation system. Herein we report the synthesis of nickel–platinum (Ni–Pt) bimetallic nanoparticles supported on mesoporous alumina (MA) using a simple one-pot evaporation-induced self-assembly method. The Ni–Pt/MA catalyst exhibits excellent activity and satisfactory stability for selectively catalyzing the decomposition of hydrous hydrazine to generate hydrogen at mild temperatures, which compares favorably with the performance of the catalysts developed to date. The facile synthesis of high-performance and cost-effective Ni-based catalyst is of clear significance for the development of hydrous hydrazine as a viable hydrogen carrier.

The microstructure–property relationship of Nb-free and Nb-bearing ultrahigh strength steels were studied in this work. Martensitic steels with 1800 MPa tensile strength were obtained by conducting reheated quenching and tempering after thermomechanical rolling. The microstructures of the steels were investigated by scanning electron microscopy, transmission electron microscopy electron backscattering diffraction technique. The results show that with the addition of Nb, the prior austenite grain growth was impeded, which leaded to the further refinement of final martensite microstructure. Randomly distributed Nb-rich (Nb,Ti)C in Nb bearing steel played an important role in the strengthening of the steel. As revealed by dilatometry and differential scanning calorimetry, with the increase of tempering temperature the decrease of mechanical properties mainly initiated by the decomposition of retained austenite during low temperature tempering, and the formation of harmful iron carbides was retarded when the steel microalloyed with 0.021% Nb.

Repeated experiments were done to study of influence of sensitization process on quality of mixed loading emulsion explosive, the results show that: The ratio of the sensitizing agent at 1:10 ~1:30 are more appropriate; the density of mixed loading emulsion explosive is gradually decreased while concentration of sensitizing agent increased. Emulsion explosive quality is affected by foaming time under the condition of the certain proportion of sensitizer and constant temperature, when the sensitizer mixing time extended to a certain value, the density tends to be stable. Under the condition of invariable sensitizer concentration, proper temperature not only obtain good blasting effect, but also improve the charging efficiency and shorten the charging time; the temperature between 30~50 °C is more appropriate when the ratio of sensitizer is certain.

Three antimicrobial nanoparticle types (AMNP0, AMNP1, and AMNP2) produced using the TesimaTM thermal plasma technology were investigated and their compositions were determined using a combination of analytical methods. Scanning electron micrographs provided the morphology of these particles with observed sizes ranging from 10 to 50 nm, whilst FTIR spectra confirmed the absence of polar bonds and organic impurities, and strong Raman active vibrational bands at ca. 1604 and 1311 cm-1 ascribed to C-C vibrational motions were observed. Carbon signals that resonated at δC 126 ppm in the solid state NMR spectra confirmed that sp² hybridised carbons were present in high concentration in two of the nanoparticle types (AMNP1 and AMNP2). X-ray powder diffraction suggested that AMNP0 contains single phase Tungsten carbide (WC) in a high state of purity and multiple phases of WC/WC1-x were identified in both AMNP1 and AMNP2. Finally, X-ray photoelectron spectral (XPS) analyses revealed and quantified the elemental ratios in these composite formulations.

The finite-element software ANSYS/LS-DYNA was used to study the influence of various parameters of barrier hole on the vibration-decreasing effect, such as the diameter, spacing, depth, hole number and row number of barrier holes and distance from blast holes to barrier holes. The simulation study indicates that: vibration-enhancing area and vibration-decreasing area exist together behind the barrier holes; various parameters of barrier holes can apparently affect the location, range and results of the vibration-enhancing area and the vibration-decreasing area; With bigger diameter, shorter distance, larger number and deeper barrier holes, the better vibration-decreasing results will come out; Under the conditions of numerical simulation in this paper, the effect of double-row barrier holes are better than that of single-row barrier holes, and the effect of vibration-decreasing of triangle layout form is almost the same as rectangle layout form of barrier holes; the changing distance between vibration barrier holes and blast holes will have a fluctuating effect on the vibration-decreasing effect, thus we should select the best location of vibration barrier holes based on the actual engineering conditions in practical engineering. The largest vibration-decreasing ratio of the barrier holes we have obtained at the test site is 33.3%, which is successfully utilized in the production explosion, so we have verified effectiveness of vibration-decreasing effect of the barrier holes.

In blasting excavation of shallow tunnel, the surface vibration of excavated tunnel can be amplified due to effect of hollow. This effect is an important factor for safety of surface buildings. Based on the measured data of one tunnel excavation project, combining wavelet analysis and AOK time-frequency distribution method, the surface vibration signals in front and rear position of working face are processed into different frequency bands. Taking PPV, dominant frequency, d7 (7.8125-15.625 Hz) band energy ratio and d7 (7.8125-15.625 Hz) band energy duration as indexes, the effect of hollow on time-frequency characteristics of surface vibration signal is studied in this article. The results show that, affected by the hollow in excavated region, the PPV and dominant frequency increase, and the d7 (7.8125-15.625 Hz) band energy shows fluctuant ratio of total energy and an increase of band energy duration. The results show that the hollow influence on the frequency characteristics of the surface vibration signals comprehensively, and also provide an analytical basis for anti-vibration and vibration reduction study from the angle of energy.

In this paper, we report a careful study of the properties and mechanisms of a 2LiBH4–MgH2 composite with a niobium oxide (Nb2O5) additive. It was found that directly milling with a small amount of the Nb2O5 additive exerted a negligible effect on the dehydrogenation kinetics of the 2LiBH4–MgH2 composite in the first cycle. However the recycled sample showed notable property advantages over the neat 2LiBH4–MgH2 composite. Phase/chemical state analyses and control experiments were conducted to gain insight into the chemical transformation of the Nb-containing species. It was found that the Nb2O5 additive reacted with LiBH4 to form a niobium boride (NbB2) heterogeneous nucleation agent, via a niobium hydride (NbH2) intermediate, in the dehydrogenation process of the composite sample. The retarded formation of the NbB2 is a major mechanistic reason for the observed drastic property change of the composite upon cycling. As a solution, we employed a novel three-step method to controllably promote the formation of the targeted NbB2 species and improve its dispersion state. As expected, the 2LiBH4–MgH2–0.08Nb2O5 composite sample, prepared using the new method, exhibits rapid dehydrogenation kinetics and high cyclic stability, which compare favorably with the literature results of the 2LiBH4–MgH2 composites with transition metal additives.

To develop a new magnesium alloy with excellent formability at room temperature, the effect of Y, Ce, and Gd addition on texture and stretch formability of Mg–1.5Zn alloys was carried out. The result shows that Y, Ce, and Gd addition in Mg–1.5Zn alloys can effectively weaken and modify the basal plane texture, characterized by TD-split texture in which the position of basal is titled from normal direction (ND) toward transverse direction (TD). When Mg–1.5Zn alloy with Gd addition appears low texture intensity and TD-split texture, where the position of basal poles is tilted by about ±35° from ND toward to TD, the largest Erichsen value of 7.0 and the elongation rate reaches 29.1 % in TD direction. However, Y and Ce addition in Mg–1.5Zn alloys promote a large number of second phase particles, which cancel the contribution of the unique basal texture to stretch formability and ductility.

Catalyst study is a central issue in the development of sodium borohydride (NaBH 4 )-based hydrogen generation systems. Here, we report the preparation, characterization and utilization of a novel cobalt–molybdenum–boron (Co–Mo–B) catalyst. Our study found that the Co–Mo–B catalyst prepared by chemical reduction method using an ethylene glycol solution of cobalt chloride exhibits remarkably higher catalytic activity than the Co–B and Co–Mo–B catalysts prepared in aqueous solution. On the basis of the phase, microstructure and elemental chemical state analyses, the mechanistic reasons for the improved performance of the newly prepared Co–Mo–B catalyst were discussed. Our study demonstrated that the combined usage of concentrated NaBH 4 solution, Co–Mo–B catalyst and a small amount of Al powder constitutes a high-performance hydrogen generation system, which can yield >6 wt% hydrogen with fast kinetics and high fuel conversion.

The supercritical CO2-based technologies have been widely used in the formation of drug and/or polymer particles for biomedical applications. In this study, nanoparticles of poly-(methyl vinyl ether-co-maleic anhydride) (PVM/MA) were successfully fabricated by a process of solution-enhanced dispersion by supercritical CO2 (SEDS). A 23 factorial experiment was designed to investigate and identify the significance of the processing parameters (concentration, flow and solvent/nonsolvent) for the surface morphology, particle size, and particle size distribution of the products. The effect of the concentration of PVM/MA was found to be dominant in the results regarding particle size. Decreasing the initial solution concentration of PVM/MA decreased the particle size significantly. After optimization, the resulting PVM/MA nanoparticles exhibited a good spherical shape, a smooth surface, and a narrow particle size distribution. Fourier transform infrared spectroscopy (FTIR) spectra demonstrated that the chemical composition of PVM/MA was not altered during the SEDS process and that the SEDS process was therefore a typical physical process. The absolute value of zeta potential of the obtained PVM/MA nanoparticles was larger than 40 mV, indicating the samples’ stability in aqueous suspension. Analysis of thermogravimetry-differential scanning calorimetry (TG-DSC) revealed that the effect of the SEDS process on the thermostability of PVM/MA was negligible. The results of gas chromatography (GC) analysis confirmed that the SEDS process could efficiently remove the organic residue.

The technology of spontaneous heating is a new method of deicing and melting snow.It puts electrical conductor into asphalt concrete.After electrical conductor sending out heat,temperature of pavement will be increased.Untill temperature is higher than freezing point,ice and snow will be melted.According to theory of heating,a model of finite element is designed.Based on ANSYS,temperature field of pavement layer and temperature distribution of pavement surface,ascending rule of temperature,warm-up time,affection of deicing and snow-melting are researched.Finally,curved line and analyzed result of deicing and melting snow are received.The result can demonstrate the feasibility of technology of spontaneous heating to deice and melt snow on airport pavement.

Lysozyme-loaded polymeric composite microparticles were successfully coprecipitated by solution-enhanced dispersion by supercritical CO2 (SEDS), starting with a homogeneous organic solvent solution of lysozyme/poly(L-lactide)/poly(ethylene glycol) (lysozyme/PLLA/PEG). The effects of different drug loads (5, 8, and 12% w/w), PLLA Mw (10, 50, 100, and 200 kDa), PEG contents (0, 10, 30, and 50% PEG/(PLLA+PEG) w/w), and PEG Mw (400, 1000, and 4000 kDa) on the surface morphology, particle size, and drug release profile of the resulting composite microparticles were investigated. The results indicate that the size of the microparticles decreased and the rate of drug release increased with an increase in drug load, PEG content, or PEG Mw; the particle size first increased and then decreased with an increase in PLLA Mw, and the drug release was controlled by both particle size and PLLA Mw. The Fourier transform infrared spectrometer analysis and circular dichroism spectra measurement reveal that no significant changes occurred in the molecular structures during the SEDS processing, which is favorable to the production of proteinpolymer composite microparticles for a protein drug delivery system. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Electroconductive Si3N4–TiN ceramic was fabricated by pressureless sintering from the chief materials containing high titanium slag and Si3N4powder synthesized by carbonthermal reduction nitridation method using iron ore tailing as raw materials. Phase constitutes and microstructure were analyzed by XRD and SEM. The densification, mechanical properties and electrical conductivity of Si3N4–TiN ceramic were also measured. Results show that the sintered samples mainly consist of Si3N4and TiN. Si3N4exhibits rod morphology and the grain sizes are about 1-3mm.TiN shows fine granular morphology with most of grain size being lower than 0.5mm. The electroconductive Si3N4–TiN ceramic has optimal properties when it is sintered at 1550°C for 2h using initial raw materials containing 20wt% TiO2. The sintered sample’s bulk density, hardness, flexure strength and room electrical resistivity are 2.79 g·cm-3, 8.23GPa, 66 MPa and 7.1×10-2W·cm, respectively.

Foam glass composite with good capabilities was prepared from iron ore tailings as the main material by two steps. The phase composition and microstructure were determined by X-ray diffraction and scanning electron microscopy. The effects of foaming temperature and sintering temperature on sample capabilities were studied by determining sample bulk density and compression strength. The results show that the main phase of basis glass powder is amorphous mineral. The foam glass composite with enclosed circle pore mainly concludes Ca[(Fe,Mg)][SiO3]2 and amorphous glass. The diameter size of pore is wide and distributes evenly. The foam glass composite, whose compression strength is 62.25MPa, and bulk density is 2.056 g/cm3, has fine complex capabilities. With the increase of foaming temperature the sample pore diameter size raises, while bulk density and compression strength reduces. The bulk density and compression strength all diminish firstly and raise subsequently with the sintering temperature increasing. The optima temperature parameters are foaming temperature of 900~950 and sinter temperature of 1100 .

Room-temperature electrical conductivity property of Si3N4/TiN composite ceramics fabricated by Si3N4 powders from iron ore tailing and high titanium slag was investigated. Si3N4/TiN composite ceramics were machined by electrical discharge machining. The results show that the minimum amount of TiO2 in initial raw materials is about 20wt% for the formation of electroconductive network in the composites, of which the electric resistivity is 4.25×10-2•cm. The electric resistivity decreases slightly with increasing the sintering temperature. Surface roughness enhances significantly with the speed of the electrical discharge machining rising.

Conventional therapeutic approaches for cancer are limited by cancer cell resistance, which has impeded their clinical applications. The main goal of this work was to investigate the combined antitumor effect of paclitaxel with small interfering RNA modified by cationic liposome formed from modified octadecyl quaternized carboxymethyl chitosan. The cationic liposome was composed of 3β-[N-(N′, N′-dimethylaminoethane)-carbamoyl]-cholesterol, dioleoylphosphatidylethanolamine, and octadecyl quaternized carboxymethyl chitosan. The cationic liposome properties were characterized by Fourier transform infrared spectroscopy, dynamic light scattering and zeta potential measurements, transmission electron microscopy, atomic force microscopy, and gel retardation assay. The cationic liposome exhibited good properties, such as a small particle size, a narrow particle size distribution, a good spherical shape, a smooth surface, and a good binding ability with small interfering RNA. Most importantly, when combined with paclitaxel and small interfering RNA, the composite cationic liposome induced a great enhancement in the antitumor activity, which showed a significantly higher in vitro cytotoxicity in Bcap-37 cells than liposomal paclitaxel or small interfering RNA alone. In conclusion, the results indicate that cationic liposome could be further developed as a codelivery system for chemotherapy drugs and therapeutic small interfering RNAs.

Precise control of the morphology, composition and structure of metal nanostructures not only effectively improves their catalytic activity and durability but also enhances their range of applications. In this work, bimetallic Au@Rh core–shell nanodendrites are synthesized by a facile one-pot hydrothermal method. Physical characterizations show that the dendritic Rh consists of two-dimensional (2D) ultrathin Rh nanoplates with a thickness of approximately 1.2 nm. For the first time, Au@Rh core–shell nanostructures are used as a catalyst for the hydrogen generation reaction from aqueous hydrazine solution (N2H4=N2+2H2, HGR-N2H4). Bimetallic Au@Rh core–shell nanodendrites exhibit improved catalytic activity and durability for the HGR-N2H4 compared with commercial Rh nanocrystals, which can be attributed to the atomically ultrathin structure of 2D Rh nanoplates and the interconnected structure of nanodendrites, respectively. Under light irradiation, bimetallic Au@Rh core–shell nanodendrites show light-enhanced catalytic activity for the HGR-N2H4, originating from the distinctive localized surface plasmon resonance of Au icosahedron cores. An easy way to make bimetallic nanoparticles with ultrathin branch-like structures that can enhance hydrogen production has been developed. Nanomaterials are useful for a wide range of applications, from targeted drug delivery to catalysts for chemical processes. In most cases, their effectiveness depends critically on their composition and shape. Now, using a one-pot hydrothermal process, Yu Chen and colleagues from Shaanxi Normal University in Xi'an, China, have synthesized bimetallic nanoparticles with branch-like structures, or dendrites, on their surfaces. These structures consist of an icosahedron-shaped core of gold surrounded by a shell of rhodium plates. When the researchers used these bimetallic core–shell nanodendrites as a catalyst for generating hydrogen from a hydrazine solution, they achieved a higher catalytic activity and durability than commercial rhodium nanocrystals. The bimetallic Au@Rh core–shell nanodendrites with ultrathin Rh nanoplate shells show the light-enhanced catalytic activity for the hydrogen generation reaction from aqueous hydrazine solution.

Using ammonium bicarbonate (AB) particles as a porogen, chitosan (CS)-based hemostatic porous sponges were prepared in supercritical carbon dioxide due to its low viscosity, small surface tension, and good compatibility with organic solvent. Fourier transform infrared spectroscopy (FTIR) spectra demonstrated that the chemical compositions of CS and poly-(methyl vinyl ether-co-maleic anhydride) (PVM/MA) were not altered during the phase inversion process. The morphology and structure of the sponge after the supercritical fluid (SCF) process were observed by scanning electron microscopy (SEM). The resulting hemostatic sponges showed a relatively high porosity (about 80%) with a controllable pore size ranging from 0.1 to 200 µm. The concentration of PVM/MA had no significant influence on the porosity of the sponges. Comparative experiments on biological assessment and hemostatic effect between the resulting sponges and Avitene® were also carried out. With the incorporation of PVM/MA into the CS-based sponges, the water absorption rate of the sponges increased significantly, and the CS-PVM/MA sponges showed a similar water absorption rate (about 90%) to that of Avitene®. The results of the whole blood clotting experiment and animal experiment also demonstrated that the clotting ability of the CS-PVM/MA sponges was similar to that of Avitene®. All these results elementarily verified that the sponges prepared in this study were suitable for hemostasis and demonstrated the feasibility of using SCF-assisted phase inversion technology to produce hemostatic porous sponges.

Stability of Ti-55 after a long-term thermal exposure was studied on samples taken from 25 mm rolled bars. In order to evaluate the variation of mechanical properties with service time, the tensile properties of this alloy after exposure at 500, 550 and 600 degrees C for times up to 3000 h were investigated. The samples were exposed under two conditions: before and after machining the specimens. It was found that both yield strength and fracture strength increase after exposure. However, both the tensile elongation and reduction in area decrease with exposure time at all three exposure temperature. For the exposure of bars, even after 500 h at 600 degrees C both the tensile elongation and reduction in area remain unchanged with exposure time. Examination of the microstructure by optical and electron microscopy shows that the factors that influence stability are: surface oxidation, decomposition of the residual beta phase and precipitation of the alpha-2 Ti3X phase. (C) 1998 Elsevier Science S.A.

Lysozyme (LSZ)-loaded poly-L-lactide (PLLA) porous microparticles (PMs) were successfully prepared by a compressed CO2 antisolvent process in combination with a water-in-oil emulsion process using LSZ as a drug model and ammonium bicarbonate as a porogen. The effects of different drug loads (5.0%, 7.5% and 10.0%) on the surface morphology, particle size, porosity, tapped density and drug release profile of the harvested PMs were investigated. The results show that an increase in the amount of LSZ added led to an increase in drug load (DL) but a decrease in encapsulation efficiency. The resulting LSZ-loaded PLLA PMs (LSZ-PLLA PMs) exhibited a porous and uneven morphology, with a density less than 0.1 g·cm−3, a geometric mean diameter of 16.9–18.8 μm, an aerodynamic diameter less than 2.8 μm, a fine particle fraction (FPF) of 59.2%–66.8%, and a porosity of 78.2%–86.3%. According to the results of differential scanning calorimetry, the addition of LSZ improved the thermal stability of PLLA. The Fourier transform infrared spectroscopy analysis and circular dichroism spectroscopy measurement reveal that no significant changes occurred in the molecular structures of LSZ during the fabrication process, which was further confirmed by the evaluation of enzyme activity of LSZ. It is demonstrated that the emulsion-combined precipitation with compressed antisolvent (PCA) process could be a promising technology to develop biomacromolecular drug-loaded inhalable carrier for pulmonary drug delivery.

The effects of hydrogen treatment on the microstructure, lattice defects and mechanical properties of α-Ti were investigated by optical and electron microscopy, positron annihilation techniques and mechanical testing experiments. It is found that there are always two types of hydrides: the ordered f.c.t. γ-hydride and f.c.c. δ-hydride, in hydrogenated α-Ti at room temperature. The observation of the former is a new result in the TiH system with relatively high hydrogen content ([H] ≈ 32.6 at.%). However, the amount of γ-hydride appears to decrease when [H] is progressively increased. The amount of defects in the hydrogenated specimens is much more than in the dehydrogenated specimens. The defects generated by hydride formation are mainly dislocations and they become vacancy-like defects as the hydrogen content increases. The amount and morphology of the hydrides and the types of defects produce a significant effect on the microstructure of the matrix after dehydrogenation. Thus, by carefully controlling the hydrogen content one can improve the tensile and fatigue properties of α-Ti after dehydrogenation.