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Povidone iodine (PVP‐I) is widely used as an efficient antiseptic disinfectant, which can kill various pernicious microbe. PVP‐I also exhibits certain toxic effects to the environment. To study the comprehensive toxic effects of PVP‐I on microalgae, different concentrations including 0, 7, 14, 28, 56 and 112 mg/L were set. The effects of PVP‐I on the growth performance, microstructure, photosynthesis, antioxidant levels and photosynthesis associated genes expressions of microalgae were investigated. The results showed that PVP‐I had significant effects on the growth and physiological functions of C. pyrenoidosa. Under the observation of scanning electron microscope, PVP‐I of 56 and 112 mg/L could destroy the cytoderm of C. pyrenoidosa directly. Under the PVP‐I exposure, the activity of SOD and CAT fluctuated up and down, while MDA content continued to rise. The relative gene expression of PsbA gene was significantly up‐regulated in high concentration of 112 mg/L PVP‐I. The relative gene expression of rbcL and rbcS gene were upregulated in 28 mg/L PVP‐I. The results of present study showed that PVP‐I could induce the production of oxidative stress response in C. pyrenoidosa, inhibit the expression of genes related to photosynthesis of C. pyrenoidosa and affect the photosynthesis of C. pyrenoidosa. The present study will provide a reference for the safe application of PVP‐I. [ABSTRACT FROM AUTHOR]

Low-cycle fatigue and creep-fatigue tests were conducted at 815 °C on laser-welded, selective laser melted (SLM) Inconel 625 test specimens. The results showed that the microstructure of the welding zone was mainly composed of columnar dendrites, which grew epitaxially from the weld line and exhibited better fatigue and durability resistance than the non-welded SLM alloy. The low-cycle fatigue life and creep-fatigue life decreased with increasing test stress. Both fatigue and creep-fatigue properties were better for laser-welded SLM Inconel 625 specimens than non-welded specimens. High-density intergranular cracks formed in the γ matrix at base material, which contained many intergranular precipitates. Precipitation of intermetallic δ , γ ″ , and the intergranular carbides was responsible for the higher hardness of the fatigue and creep-fatigue specimens. [ABSTRACT FROM AUTHOR]

A strong strain hardening ability in ultra-high strength spring steel 60Si2CrVAT was achieved by the design of multiphase microstructures using a quenching-partitioning-tempering process. The microstructure consisted of ~ 70% martensite/bainite and ~ 30% retained austenite, which was obtained at an optimized partitioning temperature of 380 °C. The corresponding yield strength ratio and the product of strength and elongation were 0.81 and 34,828 MPa%, respectively. Interestingly, this sample exhibited a double-stage strain hardening characteristic with a concave-down shape, which was distinct from that of the other samples. The excellent performance of the ultra-high strength spring steel was mainly due to the interactions between the multiple phases and the stability of the retained austenite during cold deformation. This paper provides a new way of obtaining a strong strain hardening ability in ultra-high strength steels, which is expected to be applicable to the cold coiling process. [ABSTRACT FROM AUTHOR]

Si-B-C ceramics with different elemental compositions and microstructures were prepared by the pyrolysis of an o-carborane-containing poly(silylene-arylacetylene) ( CB- PSA) thermoset at 1000°C, 1200°C, 1300°C, and 1450°C. The thermo-oxidative stability of the ceramics was investigated by tracing the weight loss of ceramics during the isothermal oxidation at 800°C, 1000°C, and 1200°C under dry oxygen. The chemical bonding states of the ceramics before oxidation and the elemental compositions of the ceramics after oxidation were analyzed by X-ray photoelectron spectroscopy ( XPS). The surface morphologies of the ceramics after oxidation were recorded using scanning electron microscopy ( SEM). The results show that the Si-B-C ceramic prepared at 1450°C produces an integral borosilicate film on the surface of the ceramics when oxidized at both 1000°C and 1200°C and exhibits better oxidation resistance than the other Si-B-C ceramics prepared at 1000°C, 1200°C, and 1300°C. Oxidation temperatures, elemental compositions, and crystallites of the Si-B-C ceramics are found to influence the formation of the borosilicate films which plays an important role in the thermo-oxidative stability of the ceramics. [ABSTRACT FROM AUTHOR]

BACKGROUND Recently, in consideration of the rapidly increasing demand for meat products and the trend towards fast food consumption, the prepared boneless pork chop, as a new style of value-added product, is cut from pork loins and welcomed by consumers after marinating or further cooking. The effect of different tumbling marinade treatments (control group, CG; conventional static marinade, SM; vacuum continuous tumbling marinade, CT; vacuum intermittent tumbling marinade, IT) on the water status and protein properties of prepared pork chops was investigated. RESULTS The CT treatment significantly increased T22 peak area ratio compared with other treatments ( P < 0.05). Histological microstructure results showed that CT treatment significantly increased solubility of salt-soluble proteins and decreased muscle fiber diameter compared with other treatments ( P < 0.05). The net enthalpy (Δ H) of IT treatment was significantly lower than SM treatment ( P < 0.05), whereas the protein denaturation temperature ( Tm3) and Δ H3 of CT treatment were lower than IT treatment. CONCLUSION These results suggest that CT treatment was more effective in improving the water mobility and distribution, promoting the denaturation of muscle protein and accelerating the marinade efficiency of pork chops compared with other treatments. Thus CT treatment should be adopted. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The three-dimensional 6-directional variable cross-sectional cone-shaped tubular braided fabric (6DCTBF) has been applied successfully as the components in aerospace craft. The application of cone-shaped tubular braided fabric requires the densification of a small end to ensure ablation uniformity during composite fabrication. In this paper, in order to meet the size and performance requirements for 6DCTBF, a unique yarn-thinning technique used in the braiding process has developed and explained in detail by first analyzing the fiber bundle movement and distribution in modeling. After the yarn has been thinned, different zones are divided according to the constituting method of the yarn in its unit cell. Geometric models are built for different zones to determine the geometrical dimensions and volume fraction variation range. It has been shown that the theoretical model can accurately describe the 6DCTBF and provide a theoretical basis for the design of its structure and properties. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) sinking woven quartz fiber-reinforced silica composites were successfully prepared by silicasol-infiltration-sintering process at a low temperature of 450°C. The density of the composites was 1.74 g/cm3. The characteristics of 3D sinking woven structure were determined. Flexural strength and shear strength of the composites were investigated along the warp and weft directions. Both flexural stress–displacement curves in warp and weft directions had two fractural points, e.g. matrix fracture point and fiber fracture point. The shear stress–displacement curves exhibited mostly nonlinear behavior. The composite in warp and weft direction reflects different shear behavior. Microstructural observations revealed that the adhesion strength between the fibers and the matrix was weak. There was a good state without serious degradation of quartz fibers during the preparation. Apart from these, the composites exhibited an extensive and long fiber pullout in the fracture surface. Crack deflection and fiber pullout contributed to the good toughness of the composites under the loading. [ABSTRACT FROM AUTHOR]

A novel oxidation resistant SiC/B4 C/C nanocomposite was prepared by the pyrolysis of carborane-containing poly(silyleneethynylenephenyleneethynylene) ( CB- PSEPE) at 1450°C in argon. The phase composition and microstructure of the carbon-rich ceramic were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The β- SiC (~12 nm) and B4 C (~20 nm) nanocrystalline phases were formed during the pyrolysis process of CB- PSEPE. The presence of boron in CB- PSEPE promotes the growth of β- SiC nanocrystals. The ceramic shows excellent thermooxidative stability based on thermogravimetric analysis in air. A borosilicate layer was formed on the surface of the ceramic after oxidation. This carborane-containing conjugated polycarbosilane could be a potential precursor for oxidation resistant carbon-based materials. [ABSTRACT FROM AUTHOR]

The microstructures of 20CrNi2Mo steel underneath the contact surface were examined after dry sliding. Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Backscattered Diffraction (EBSD) and an ultra-micro-hardness tester were used to characterize the worn surface and dry sliding wear-induced layer. Martensite laths were ultra-refined due to cumulative strains and a large strain gradient that occurred during cyclic loading in wear near the surface. The microstructure evolution in dominant abrasive wear differs from that in adhesive wear. In dominant abrasive wear, only bent martensite laths with high-density deformation dislocations were observed. In contrast, in dominant adhesive wear, gradient structures were formed along the depth from the wear surface. Cross-sectional TEM foils were prepared in a focused ion beam (FIB) to observe the gradient structures in a dry sliding wear-induced layer at depths of approximately 1–5 μm and 5–20 μm. The gradient structures contained nano-laminated structures with an average thickness of 30–50 nm and bent martensite laths. We found that the original martensite laths coordinated with the strain energy and provided origin boundaries for the formation of gradient structures. Geometrically necessary boundaries (GNBs) and isolated dislocation boundaries (IDBs) play important roles in forming the nano-laminated structures. [ABSTRACT FROM AUTHOR]

Porous alumina ceramic was prepared with a combined technique of three–dimensional printing and sintering. The optimal sintering temperature for porous alumina ceramic is in the range of 1300–1400 °C. The CaSO 4 –dextrin content of green body has a decisive effect on the phase composition and flexural strength but a little effect on the porosity and Vickers hardness of porous alumina ceramic. The alumina ceramic prepared from the green body with CaSO 4 –dextrin content in the range of 12–16 wt% possesses a flexural strength higher than 80 MPa, a porosity of about 50% and a tailored microstructure, which is a promising material for engineering applications. [ABSTRACT FROM AUTHOR]

Chrysanthemum-like ZnO nanowire clusters with different Mn-doping concentrations are prepared by a hydrothermal process. The microstructure, morphology and electromagnetic properties are characterized by x-ray diffractometer high-resolution transmission electron microscopy (HRTEM), a field emission environment scanning electron microscope (FEESEM) and a microwave vector network analyser respectively. The experimental results indicate that the as-prepared products are Mn-doped ZnO single crystalline with a hexagonal wurtzite structure, that the growth habit changes due to Mn-doping and that a good magnetic loss property is found in the Mn-doped ZnO products, and the average magnetic loss tangent tandm is up to 0.170099 for 3% Mn-doping, while the dielectric loss tangent tande is weakened, owing to the fact that ions Mn2+ enter the crystal lattice of ZnO. [ABSTRACT FROM AUTHOR]

In this paper, creep-fatigue behaviors of the thin-walled tubular specimen with film holes were experimentally studied to address the influence of cyclic stress interruptions on creep strength and creep-fatigue life of a directionally solidified superalloy. The specimens with and without multiple holes were designed and manufactured to consider the effect of stress concentration produced by film cooling holes. The creep life of the specimen with holes has reduced significantly with the introduction of fatigue. An interesting result was found that the creep strength and life was enhanced on the stress concentrated specimens even if the creep loading was interruption by fatigue loadings, while creep fatigue life will be commonly shortened for notched specimen. Failure mechanisms related with cooling holes were analyzed on the basis of microscope observation. • Creep-fatigu tests of specimens with film-cooling holes were carried out. • Fatigue creep interaction is reflected in the formation of dimples. • High-temperature deformation and stress concentration is a key factor leading to damage. • The creep life of the specimen with holes has reduced with the introduction of fatigue. • The relationship between rafting type and stress state around film cooling hole was found. [ABSTRACT FROM AUTHOR]

Silica composites (2.5D quartz fibers-reinforced) were prepared by the silicasol-infiltration-sintering method. The fiber volume fraction was 50.5%. The composites were sintered in a temperature range of 400∼450°C. Mechanical properties of the composites were determined by pc-controlled electronic universal testing machines. The microstructure of the composite was observed by scanning electron microscopy (SEM). The density of the composite was 1.77 g/cm3. The flexural strength and the shear strength of the composites were 50.35 MPa and 22.41 MPa, respectively. The stress-deflection curves exhibited mostly nonlinear behavior; the failure was not catastrophic. Some fibers pull-out indicated that the composite had part toughness. However, abundant fibers fractured in the same plane revealed that the composite presented serious brittleness. The fracture mechanism of the composite was a mixture of ductile and brittle modes.

Abstract: The effect of two different fiber architectures on the mechanical properties and mechanical behavior of the SiO2f/SiO2 composites processed by silicasol-infiltration-sintering has been investigated. The composites were sintered at relatively low temperature (450°C). The fiber/matrix interface strength was weak. The characteristics of 2.5D (shallow straight-joint) structure and 3D four-directional braided structure were determined. The tensile strength, flexural strength, shear strength and failure mechanisms of both 2.5D (shallow straight-joint) and 3D four-directional braided SiO2f/SiO2 composites were characterized. It was found that the fiber placement in the preform will strongly affect the mechanical property and failure behavior of the composite. The results of the tests and microstructural observations indicated that 3D four-directional braided SiO2f/SiO2 composite had better mechanical properties than 2.5D (shallow straight-joint) SiO2f/SiO2 composite. 3D four-directional braided SiO2f/SiO2 composite exhibited more graceful failure under loading than 2.5D (shallow straight-joint) SiO2f/SiO2 composite. [Copyright &y& Elsevier]

Abstract: 3D orthogonal quartz fiber reinforced silica composites were fabricated by silicasol-infiltration-sintering method at a low temperature of 450°C, and the mechanical properties and microstructure of the composites were investigated. The density of the composites was 1.71g/cm3, the average values of flexure strength and shear strength of the composites were 29.4MPa and 14.8MPa at room temperature, respectively. Both of the failures under flexural loading and shear loading were not catastrophic. Compared with α-quartz and α-cristobalite, the fracture toughness of 3D orthogonal quartz fiber reinforced silica composites has been enhanced by a wide margin. The damage features of the composites are identified, using digital camera and scanning electron microscopy. There was a good state without serious degradation of quartz fibers during the preparation. The bonding between the matrix and the incorporated fibers is weak, and the matrix cracks propagate along the weak interface. Apart from this, the composite is found to exhibit an extensive and long fiber pull-out in the fracture surface. Crack deflection and fiber pull-out contributed to the good toughness of the composite under the loading. [Copyright &y& Elsevier]

Abstract: The effect of two different fiber architectures on the mechanical properties of the quartz fiber-reinforced silica composites processed by silicasol-infiltration-sintering (SIS) has been investigated. The composites were sintered at relatively low temperature (450°C). The characteristics of 2.5D (shallow bend-joint) structure and 3D orthogonal structure were determined. The microstructures, flexural strength, shear strength and failure mechanisms of both 2.5D (shallow bend-joint) and 3D orthogonal composites were characterized. It was found that the fiber placement in the preform will strongly affect the mechanical property and failure behavior of the composite. The results of the tests and microstructural observations indicated that 2.5D (shallow bend-joint) quartz f /silica (Q f /S) composites had better mechanical properties than 3D orthogonal quartz f /silica composites. [Copyright &y& Elsevier]

Abstract: 2.5D (shallow straight-joint) quartz fibers-reinforced silica composites were successfully prepared by silicasol-infiltration-sintering method. The composites were sintered at 450°C and the density of the composite was up to 1.70g/cm3 after 11 infiltration-sintering cycles. The characteristics of 2.5D (shallow straight-joint) structure were determined. Flexural strength and shear strength of the composites were investigated along the warp and weft directions. The undulation of warp yarns could reduce the mechanical properties of the composites along warp direction. The flexural and shear stress-deflection curves exhibited mostly nonlinear behavior. The failure was not catastrophic. Some fibers pull-out indicated that the composite exhibited a certain degree of toughness. Microstructural observations revealed that the interface strength between the fiber and the matrix was weak for the relatively low sintering temperature of 450°C. [Copyright &y& Elsevier]

Abstract: C/SiC composites were prepared by polycarbosilane infiltration pyrolysis and ablated by oxyacetylene flame at 1800°C for 180s. Morphology and microstructure of C/SiC have been studied by scanning electron microscopy/energy dispersive spectroscopy, and X-ray diffraction analysis. Two concentric ring regions appeared on the surface of the ablated C/SiC. In the centre region of the ablated C/SiC was composed of irregular SiC particles with a lot of pores. The pores were resulted from (i) gas expansion in closed pores during ablation, and (ii) from the release of SiO gas produced by the oxidation of SiC with sufficiently low oxygen partial pressure. The results indicated the ablation was due to a combination of oxidation, mechanical erosion and recrystallization of the surface SiC. [Copyright &y& Elsevier]