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SnO2 powders with four distinct morphologies of prismoids, hollow rhomboidal tubes, solid rhomboidal rods, and needles have been prepared through morphology-conserved transformation from SnC2O4 precursors. The SnC2O4 precursors were synthesized by a facile oxalate precipitation method. A controllable periodic bond chain (PBC) growth was found to be critical for the formation of these SnC2O4 samples. In the case of forward titration, SnC2O4 prismoids were generated because the formed Sn3O(OH)2SO4 was attached on { 1 ( _ ) 01} polar facets and inhibited the PBC growth along the c axis. By contrast, in the case of reverse titration, SnC2O4 samples preferably formed one-dimensional shapes. Dissolution and ripening were observed during the formation of hollow tubes in the case of low molar ratio of Sn2+ to C2O42−. Further, the formation of SnC2O4 needles was ascribed to the selective coordination of polyvinylpyrrolidone (PVP) on the side surface. The as-prepared SnO2 powders were used as reinforcement of Ag–SnO2 electrical contact materials, and a good adhesion was observed at the Ag (111)/SnO2 (200) interface. Further, the characterization results revealed that the sample reinforced by SnO2 tubes (with one-dimensional shape and hollow structure) had the lowest degradation rate under cathode arc erosion, which might be attributed to its good resistance to the dual action (heat and force) of cathode arc.

Three-dimensional (3D) continuous Ni-network-reinforced Ag-matrix composite materials were prepared by hot-pressing Ag–Ni composite powders with Ni powders coated on the surface of Ag granules. The formation of a 3D continuous Ni network enhances the load transferred from the Ag matrix to the second-phase Ni, inducing the co-deformation of Ag and Ni during the drawing deformation. The co-deformation begins as orientation rotation and refinement; e.g. the Ag matrix slips on {111}〈1 1 - 0〉, twins on {111}〈11 2 - 〉, and 〈100〉 drawing texture are formed in second-phase Ni along the drawing direction. Finally, the 3D continuous Ni networks were torn and drawn into belts that are parallel to the axial direction of the composite wire. Increasing the real strain could increase the length of the Ni belts in the axial direction, thus increasing the hardness and electrical conductivity of Ag–Ni electrical contact materials. Additionally, the two-dimensional characteristics of the belts with high profile drag increase the flow resistance of molten Ag. Therefore, the belt-reinforced Ag–Ni electrical contact materials show a low mass loss after 100000 times of contact (1.8 mg, only 22.8% of that of the round fibres reinforced sample).

Silver-matrix composites are the most important electric contact materials. Here, porous Y2O3 fiber-reinforced silver composites were prepared by the hot-press sintering. Y2O3 fibers, composed of nanocrystals with a size of around 50 nm, were obtained by the infiltration and calcination method using cotton as the template. Among these nanocrystals, pores were clearly observed. This hierarchical structure enabled the deposition of silver on the inner and outer surface of Y2O3 fibers during the subsequent reduction process. Bunched Ag-Y2O3 mixed powders were thus obtained. After the hot-press sintering, the fibrous structures were uniformly distributed in Ag matrix. In each fibrous zone, Ag particles nearly filled the whole fibrous zone, and Y2O3 particles scattered among these Ag particles. This unique structure enabled Ag-Y2O3 composites to have excellent mechanical and electrical properties. Among all samples, Ag-15 vol% Y2O3 composite exhibited the best properties, which had the high density (9.67 g cm−3), high hardness (12.13 ×102 N mm−2), high conductivity (71.42% IACS), high breakdown strength (3.04 ×106 V m−1), and no silver splashing was observed on its surface after 200 times arc ablation.

Ag–28Cu–8Sn (wt%) alloy is a widely used brittle silver-based brazing filler metal. The wire of brazing filler metal was prepared by continuous casting process and dieless drawing technology. The phase structure was measured by X-ray diffraction (XRD), and the microstructure of wetting interface, cast states, processing states and fracture morphologies were characterized by the optical microscopy (OM) and scanning electron microscopy (SEM), respectively. The electrical conductivity, hardness, tensile strength and elongation rate were tested as well. Furthermore, the solid–liquid phase temperature was measured by a differential scanning calorimeter (DSC), and the wettability of brazing filler metal was tested by spreading method. The outcomes obtained show that the as-cast microstructure is a typical three-zone structure, including region of surface fine grain, zone of columnar grain and region of center equiaxed crystal. Ag–28Cu–8Sn alloy is mainly composed of Ag-rich α-phase, Cu-rich β-phase and intermediate compounds. Grain refinement appears in the cross section, as for grains of the longitudinal section, the shape is changed from ribbon to fiber to form a silk texture. The strength and hardness improve with the increase in the true strain, while the conductivity and elongation are reduced. Furthermore, the solid-phase temperature is 605.9 °C, and the liquid-phase temperature is 725.1 °C. The spreading area of Ag–28Cu–8Sn brazing filler metal is 174 mm2, and the metallurgical bonding occurs between Ag–28Cu–8Sn brazing filler metal and Cu matrix. In addition, compared with cold drawing process, there are not any microcracks at the fracture morphology for the alloy fabricated by dieless drawing. The dieless drawing process overcomes some processing defects of traditional cold drawing, and the processing performance of Ag–28Cu–8Sn alloy is improved.

Ag/Ti 3 AlC 2 composites are promising sliding contact material. Here, Ag/Ti 3 AlC 2 composites were obtained via the hot pressing technique and their structure evolutions upon sintering temperature were investigated. Sintering temperature controlled the deintercalation of Al layers from Ti 3 AlC 2 , thus controlling the interfacial structure of Ag/Ti 3 AlC 2 composites. Amorphous interface was found after sintering at 750 °C. TiC x particles with a size of around 10 nm were found in the interfacial region after sintering at 800 °C. Increasing sintering temperature to 850 °C, stripy structures composed of alternately arranged silver-rich phase and TiC x phase appeared around the edges of Ti 3 AlC 2 particles. The over-saturated Al precipitates found in 850 °C sintered composites are cubic μ -Ag 3 Al inter-metallic compounds, which have the coherent relationship with Ag matrix.

Background Contrast-induced nephropathy (CIN) is a serious complication of percutaneous coronary intervention which can cause serious adverse outcomes. There is still no effective treatment for it. Aims To evaluate and compare the protective effect of trimetazidine and nicorandil on renal function in patients undergoing percutaneous coronary intervention.with estimated glomerular filtration (eGFR) >60 ml/min/1.7 m2. Method 161 patients who met the inclusion criteria were recruited and divided into control group (n=41), trimetazidine group (n=40), nicorandil group (n=40) and trimetazidine combined with nicorandil group (n=40). Both TMZ and nicorandil were administered orally 72 hours before and 48 hours after the procedure. All patients in the four groups were given intravenous saline (0.9%) at a rate of 1 ml/kg/h 6 hours before and 12 hours after the procedure. Serum creatinine (SCr), GFR were measured before and 48 hours after the procedure. An increase of 44mmol/L (0.5mg/dL) in SCr or 25% higher than basal levels at 48 hours after administered iodinated CM was diagnosed as CIN. Results (1) The baseline characteristics of the four groups were similar. (2) The SCr levels increased in control group (baseline 73.07±15.69 VS. after PCI 91.71±23.10 mmol/L), TMZ group (baseline 71.90±17.30 VS. after PCI 82.00±17.19 mmol/L), nicorandil group (baseline 72.23±15.95 VS. after PCI 81.45±18.30 mmol/L)and TMZ plus nicorandil group (baseline 71.13±13.50 VS. after PCI 73.35±12.64 mmol/L) at 48 hours after the procedure, all p values Conclusions TMZ and nicorandil exerted similar protective effect on renal function by decreasing SCr level and CIN incidence after PCI. The efficacy of TMZ combined with nicorandil on renal protection was greater than TMZ or nicorandil alone.

Ag/graphite composites, as the most well-known sliding contact material, have short lifetime resulting from its lower hardness and strength. Ti3AlC2 has high conductivity, high hardness and layered structure similar to graphite, which makes it an ideal substitute for graphite. Here, Ag/Ti3AlC2 composites were successfully fabricated via hot pressing technique. In comparison with commercial Ag/graphite composites, the obtained Ag/5 vol% Ti3AlC2 composite exhibited superior mechanical and electrical properties, that is, high hardness of 94.5 ± 0.3 Hv, high tensile strength of 220.0 MPa, and high conductivity of 59.5% IACS (the international annealed copper standard). The formation of Ag (Al) solid solution in interfacial zone, arising from the partial decomposition of Ti3AlC2, greatly enhanced the mechanical properties of Ag/Ti3AlC2 composites.

The phase stability of Zr and Ru doped Pd system has been studied using the virtual crystal approximation (VCA) in density functional theory (DFT). Three possible VCA models have been set up for Zr and Ru doped Pd system, and elastic constants and tetragonal shear constant, bulk modulus and shear modulus, Young modulus and Cauchy press, density of states in Zr and Ru doped Pd system were also analyzed. The results show that Pd-5Ru-1Zr[T(3)] is the most stable phase in Pd-Ru-Zr system according to tetragonal shear constant, and Pd-10Ru-1Zr[T(2)] is the most brittle phase and has more directional bonding according to Cauchy press. Along with replacing Pd with Ru and Zr in the solution, the structure becomes unstable both energetically and geometrically, and the increase of Ru and Zr content can improve the strength of the chemical bonding and enhance the hardness of Pd-Ru system, but reduce their phase stability.

The stability and the thermal as well as mechanical properties of AuxCuy intermetallic compounds were investigated by density functional theory (DFT). The calculated cohesive energy and the formation enthalpy of AuxCuy phases show that they are thermodynamically stable structures and the calculated lattice constants are in good agreement with those of the experiments. The heat capacities of the compounds were calculated by a quasi-harmonic approximation (QHA) method. The Debyes temperature as a function of strength of chemical binding for each compound was also discussed. The elastic properties such as bulk modulus and Young's modulus were evaluated by Viogt-Reuss-Hill approximation. The phonon spectrum and the density of phonon states of AuCu compounds were calculated to determine the stability of two AuCu phases. The new knowledge from this study will be used for future development of Au-Cu alloy system.

We demonstrated a novel methodology to promote particle growth via introducing anions, here F−, into the precursor structure, which utilized the exchangeability of NO3− anions resided in the gallery of layered Y/Eu hydroxide (LY/EuH, simply (Y/Eu)2(OH)5NO3·nH2O) nanosheets. LY/EuH was prepared by one-step freezing temperature crystallization method. Through anion-exchange reaction at room temperature, F− substituted for NO3−, and LY/EuH transformed into F−-exchanged layered Y/Eu hydroxide (LY/EuHFx, simply (Y/Eu)2(OH)z(NO3)yFx·nH2O). The phase, particle size and photoluminescence of annealed particles strongly depended on the fluorine content. Fluorine accelerated the collapse of sheet morphology and significantly promoted the particle growth. The product calcined at 1300 °C from LY/EuH consisted of particles around 200 nm in size. In contrast, the size of particles calcined at 1300 °C from LY/EuHF0.8 increased by 7.5 times, up to 1.5 μm, and the photoluminescence intensity at 613 nm increased by 1.5 times. During calcination, the oxidation reaction, including the uptake of oxygen and the outward diffusion of fluorine contained in intermediates Y2O3−y/2Fy and YOF, in conjunction with the melt of YOF, is believed to promote the mass transfer and thus accelerate particle growth. After the oxidation reaction completion, both Y2O3−y/2Fy and YOF transformed into cubic Y2O3, without leaving residues. This novel methodology exhibits great advantages and provides significant insight into the synthesis of high performance inorganic phosphors.

A sol–gel auto-combustion method was developed to synthesize the Ag–SnO 2 composite powders, which were then used as the starting material to prepare Ag–SnO 2 electrical contact materials by hot pressing. It was found that citric acid strongly influences the thermal behaviors, phase evolution, morphology and composition distribution of the Ag–SnO 2 composite powders. During the synthesis of Ag–SnO 2 composite powders, citric acid can facilitate the formation of sol solution, lower the energy required for the decomposition of dry gel, and reduce the agglomeration of particles. Besides, a comparatively high molar ratio of citric acid to metal ions prevents effectively the occurrence of composition segregation in the Ag–SnO 2 electrical contact materials. Therefore, the prepared Ag–SnO 2 electrical contact materials have good performances in density, hardness and electric conductivity.

Grain growth behaviors of Ag-Cu-Zn alloys with different contents of Zn were studied at various heat treatment temperatures and for different holding time. The experimental results show that the grain grows along with the increase of the holding time. The higher the content of Zn is, the larger the grain size will be under the same holding time. The grain growth exponent n increases and the grain growth active energy Q decreases with the increase of the content of Zn