ZZ3200-14.5/28型支架快速倒装的实践

根据桃园矿单翼相邻工作面倒装的实践,从加快综采设备的搬家速度、提高劳动效率方面,简述桃园矿综采快速倒装的几点主要做法。     

Q195冷轧板材轧制困难原因分析

针对部分Q195冷轧板材存在轧制困难的现象，进行了现场检验与分析。带状组织、混晶现象严重导致变形强化系数偏高是造成轧制困难的主要原因。     

胃动力信息采集与分析系统设计

本文设计了一套提取胃电和胃阻抗信号的胃动力信息采集与分析系统，该系统由采集系统和分析系统两部分构成。前者以单片机（ADuC834）为核心部件，实现了胃电和生物阻抗信号的同步采集和数据传输。后者对提取的阻抗信号和胃电信号运用小波多分辨分析处理，利用小波变换将胃阻抗信号从呼吸和血流信号中分离。系统可以应用于分析功能性消化不良患者胃动力的电过程和机械过程。     

Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

Novel blood-compatible waterborne polyurethane using chitosan as an extender

A series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, M_n = 1000), isophrone diisocyanate (IPDI), and 2,2′-dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain-extended by water-soluble chitosan of low molecular weight (M_n = 5000) by self-emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of novel amphiphilic sulfated ionomers by the ring‐opening reaction of an epoxidized styrene–butadiene–styrene triblock copolymer

A method for the synthesis of novel sulfated ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed. SBS was first epoxidized by performic acid in the presence of a phase‐transfer catalyst; this was followed by a ring‐opening reaction with an aqueous solution of alkali salt of bisulfate. The optimum conditions for the ring‐opening reaction of the epoxidized SBS with an aqueous solution of KHSO₄ were studied. During the ring‐opening reaction, both phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier transform infrared spectrophotometry and transmission electron microscopy (TEM). After the potassium ions of the ionomer were substituted with lead ions, the lead sulfated ionomer exhibited dark spots under TEM. Some properties of the sulfated ionomer were studied. With increasing ionic groups or ionic potential of the cations, the water absorbency and emulsifying volume of the ionomer and the intrinsic viscosity of the ionomer solution increased, whereas the oil absorbency decreased. The sulfated ionomer possessed excellent emulsifying properties compared with the sulfonated SBS ionomer. The sodium sulfated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original SBS. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurred with respect to the tensile strength. The ionomer behaved as a compatibilizer for blending equal amounts of SBS and oil‐resistant chlorohydrin rubber. In the presence of 3% ionomer, the blend exhibited much better mechanical properties and solvent resistance than the blend without the ionomer. SEM photographs indicated improved compatibility between the two components of the blend in the presence of the ionomer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Epoxidation of high trans‐1,4‐polyisoprene and its properties

A new organic‐solvent‐free water‐phase suspension method was used to synthesize partially epoxidized high trans‐1,4‐polyisoprene (TPI) to improve its properties, including oil resistance and wet‐skid resistance. The epoxidation was conducted in an aqueous peracetic acid solution and on the TPI granules prepared by a bulk precipitation method with supported titanium catalyst. The effects of the synthesis conditions, including reaction temperature, reaction time, and pH value, on the epoxy content were investigated. Epoxidized trans‐1,4‐polyisoprene (ETPI) with epoxy contents between 10 and 80% were obtained within 4 h. Both the amorphous and crystalline regions of TPI were epoxidized. The crystallization properties decreased with increasing epoxy content. ETPIs possessed lower mechanical properties than TPI but could be enhanced by vulcanization. The oil resistance and wet‐skid resistance were significantly improved after epoxidation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermoplastic vulcanizates obtained by reaction-induced phase separation: Interplay between phase separation dynamics,final morphology and mechanical properties

Reaction-induced phase separation (RIPS) of miscible blends of poly(?-caprolactone) (PCL) and an epoxy resin based on poly(propylene oxide) (PPO) was used to prepare thermoplastic vulcanizates (TPVs) with fine rubber dispersions. Scanning electron microscopy (SEM) confirmed the formation of cross-linked rubber particles dispersed in the thermoplastic matrix at PCL contents ≥20 wt%. The morphology development during phase separation was studied by optical microscopy (OM) and time-resolved small-angle light scattering (SALS). It was shown that higher curing temperatures lead to a decrease in rubber particle size, but at the same time lead to an increase in the extent of particle connectivity. In some cases, gelation of the PPO-rich phase limits full structure development, which leads to extensive connectivity between the dispersed rubber particles and a strong deterioration in tensile properties.     

Accelerated wear testing with a microfabricated surface to evaluate the lubrication ability of biomolecules on polyethylene

Wear of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and wear‐particle‐induced osteolysis and bone resorption are the major factors causing the failure of total joint replacements. It is feasible to improve the lubrication and reduce the wear of artificial joints. We need further understanding of the lubrication mechanism of the synovial fluid. The objective of this study is to evaluate the lubricating ability of three major components in the synovial fluid: albumin, globulin, and phospholipids. An accelerated wear testing procedure in which UHMWPE is rubbed against a microfabricated surface with controlled asperities has been developed to evaluate the lubrication behavior. An analysis of the wear particle dimensions and wear amount of the tests has provided insights for comparing their lubrication performance. It is concluded that the presence of biomolecules at the articulating interface may reduce friction. A higher concentration of a biological lubricant leads to a decrease in the wear particle width. In addition, in combination with the wear results and mechanical analysis, the roles of individual biomolecules contributing to friction and wear at the articulating interface are discussed. These results can help us to identify the role of the biomolecules in the boundary lubrication of artificial joints, and further development of lubricating additives for artificial joints may be feasible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effect of ionic interaction on the miscibility and crystallization behaviors of poly(ethylene glycol)/poly(L‐lactic acid) blends

The effect of end groups (2NH₂) of poly(ethylene glycol) (PEG) on the miscibility and crystallization behaviors of binary crystalline blends of PEG/poly(L ‐lactic acid) (PLLA) were investigated. The results of conductivity meter and dielectric analyzer (DEA) implied the existence of ions, which could be explained by the amine groups of PEG gaining the protons from the carboxylic acid groups of PLLA. The miscibility of PEG(2NH₂)/PLLA blends was the best because of the ionic interaction as compared with PEG(2OH, 1OH‐1CH₃, and 2CH₃)/PLLA blends. Since the ionic interaction formed only at the chain ends of PEG(2NH₂) and PLLA, unlike hydrogen bonds forming at various sites along the chains in the other PEG/PLLA blend systems, the folding of PLLA blended with PEG(2NH₂) was affected in a different manner. Thus the fold surface free energy played an important role on the crystallization rate of PLLA for the PEG(2NH₂)/PLLA blend system. PLLA had the least fold surface free energy and the fast crystallization rate in the PEG(2NH₂)/PLLA blend system, among all the PEG/PLLA systems studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008