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"Thiol-yne" click reaction has already been widely applied in synthesis and modification of new polymer structures or novel materials due to its specific features. However, in most studies, only chain-end strategy was employed when using the di-addition feature of thiol-yne reaction, thus the in-chain di-addition strategy could endow us with a broader space to develop the synthesis of advanced polymers. Therefore, in this paper, the features of in-chain mono- and di-addition were investigated when modifying the alkyne-functionalized polymers to prepare grafted polymers via thiol-yne click reaction. The results showed that it is almost impossible to obtain the in-chain di-adducts even under excess feeding of chain-end thiol-functionalized grafts, while only the in-chain mono-adducts could be obtained efficiently. Further researches investigated that the controlled grafting could be encountered when carrying out the thiol-yne click reaction between chain-end alkyne-functionalized polystyrenes and chain-end thiol-functionalized polystyrenes under proper feedings. Therefore, the effect of steric-hindrance might be the primary reason for the alternative grafting via thiol-yne click reaction between in-chain and chain-end alkyne-functionalized polymers. [ABSTRACT FROM AUTHOR]

Bismuth ferrites powders have been successfully synthesized via a facile hydrothermal method. Phase structure, morphology and surface area of as-prepared powders are investigated by using X-ray diffraction, field emission scanning electron microscope and Brunauer–Emmett–Teller (BET) method. The effects of the Bi3+/Fe3+ precursor molar ratio and the reaction time on the phase structure evolution of bismuth ferrite are systematically studied. Three types of bismuth ferrite powders, that is, sheet-like Bi2Fe4O9, sheet-like Bi2Fe4O9 hybrid with Bi25FeO40 and BiFeO3, and cuboid-like Bi2Fe4O9 with large exposed (001) surface, are obtained by tailoring the Bi3+/Fe3+ precursor molar ratio from 1.5:1 to 1:2 and the reaction time from 4 to 12 h during hydrothermal process. A reasonable mechanism for phase structure evolution is proposed and discussed on the basis of our results. Furthermore, the optical properties and photocatalytic activities of those samples are also investigated. All these powders have small bandgap energy and the bandgap reduces with the increasing size. The differences in photocatalytic activities by the degradation of Rhodamine B are well explained from phase structure and morphology. Our studies indicate that a facile hydrothermal method can be well made use of to design and synthesize bismuth ferrite powders with controllable phase structure, morphology and photocatalytic behaviors. [ABSTRACT FROM AUTHOR]

The normal T6 heat treatment process for cast A356 alloy generally requires about 15 h. This longperiod procedure increases greatly the manufacturing cost and decreases the productivity in practical production. In this study, a new short-time heat treatment process with only 30 min solution time at 540 °C was developed for the production of motorcycle wheel hubs in order to reduce heat treatment time. Comparisons on microstructure evaluation and mechanical properties, such as tensile strength and ductility, were made between this new fast process and the conventional T6 heat treatment. The results revealed that this new heat treatment process enabled the spheroidization of the eutectic silicon thoroughly, while minimizing the growth of eutectic silicon. The A356 alloy after this new short-time heat treatment shows nearly equal mechanical properties compared with the same alloy heat treated in a normal T6 heat treatment. This investigation makes it possible to significantly improve the efficiency of heat treatment on A356 alloy and, at the same time, improve the mechanical properties of the alloy. [ABSTRACT FROM AUTHOR]

The pure BiFeO and Bi AFeO (A = Ca, Ba, x = 0.03) powders are synthesized via a modified solid-state reaction method to study the effects of alkaline-earth metal ions doping on crystal structural, optical and magnetic properties. Both X-ray diffraction and Raman spectroscopy data reveal that all the powders are Mullite-type BiFeO orthorhombic single phase without any impurities. Much greater structural distortion in BiBaFeO than that of BiCaFeO is observed. The chemical compositions of Ba and Ca doped powders have been investigated with energy dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy results indicate that oxygen vacancies could be found in all doped powders. The ratio of Fe in the total Fe ions is almost unchanged by Ca doping and increases a little with Ba substitution. Compared with that of pure BiFeO the band gap values decrease slightly in BiCaFeO but drop dramatically in BiBaFeO. A clear and obvious ferromagnetic behavior is found in BiBaFeO at 10 K. However, BiCaFeO shows a weak ferromagnetism with enhanced magnetization and BiFeO exhibits antiferromagnetism with a linear M-H relationship. The varied bandgap and magnetization resulting from the alkaline-earth metal ionic species are discussed in terms of structural distortion due to the ionic radius size effect. [ABSTRACT FROM AUTHOR]

In this study, a central venous catheter (CVC)-associated infection model was established in rats to investigate and evaluate the effect of biofilms on the virulence of the pathogens. Twenty-four adult SD rats were randomly divided into biofilm positive (BF+) and biofilm negative (BF−) groups to be challenged with strains of S.epidermidis. Serum levels of inflammatory cytokines were measured and the infection rate and counts of bacteria cells were studied. Compared to rats of BF− group, the serum level of TNF and IL-6 significantly increased in rats of BF+ group ( P < 0.01) and the level of IL-10 and IFN-γ significantly decreased ( P < 0.01), striking the balance of pro-inflammatory/anti-inflammatory cytokines. The infection rate and bacterial counts in tissues and blood of rats of BF + group were significantly higher than those of rats of BF− group ( P < 0.05).Inflammatory cell infiltration in vital organs (heart, lung, liver and kidneys) was more significant in rats of BF+ group than that of rats of BF- group. CVC-associated infection model can be successfully reproduced in rats by injecting 5 × 10 CFU of S.epidermidis. Biofilm formation can significantly enhance the virulence of the bacteria, leading to uncontrolled infection. The serum level of inflammatory cytokines, infection rate and the extent of inflammatory cell infiltration are important markers for evaluating the virulence of biofilm. [ABSTRACT FROM AUTHOR]

The effect of adding Co, Ni or La on the methanation activity of a Mo-based sulfur-resistant catalyst was investigated. As promoters, Co, Ni and La all improved the methanation activity of a 15% MoO/AlO catalyst but to different extents. Similar improvements were also found when Co, Ni or La was added to a 15% MoO/25%-CeO-AlO catalyst. The promotion effects of Co and Ni were better than that of La. However, the catalytic methanation activity deteriorated the most with time for the Ni-promoted catalyst. The used catalysts were analyzed by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]