溶剂沉淀法制备的聚酰胺粉末之溶剂与粉末结构和热稳定性的关系

使用粒度分布仪、白度仪、电子显微镜和差热仪测定四种溶剂沉淀法制备的聚酰胺粉末发现：每种方法所获得的粉末粒径、比表面积、白度均不相同；以乙醇 氯化钙混合溶剂制备的粉末内部具有多孔结构；以乙醇 盐酸 水混合溶剂制备的粉末热稳定性较高     

A solution approach to the design of multi-period,multipurpose batch plants

A deterministic model for multipurpose, multiperiod batch plants was presented in a linearized form to predict the future design according to the change of demand by using a modified Benders’ Decomposition. The OSL code offered by the IBM corporation as optimizer was employed for solving several example problems. The decomposition method was successful, showing remarkable reduction in the computing times as compared with those of the direct solution method. Also the heuristic used as a solution approach for the multiperiod model provided an efficient methodology to the block-structured problem by dividing the large overall problem into the manageable single period blocks.     

制作和生产颜色釉的体会

陶瓷企业目前都面临着原料紧缺、价格上涨的问题,随着生产成本上涨和产品价格竞争的加剧,目前白坯瓷的利润很低。从这两年广交会的情况看,市场上经营的颜色釉较多,价格也较高。如果能研制生产出颜色釉,且价值还是可观的。笔者对颜色釉做大量的实验,从中获取了一些体会,希望对大家有所借鉴。1颜色釉的生产和工艺控制颜色釉在生产前都要进行中试,其结果有时会出现和封样呈色不一致现象。例如,我们公司在2004年10月份投产了深灰、浅灰和浅黄3种釉,将釉送到车间进行中试,发现3种釉色调变化都很大,其中深灰釉泛绿色,浅灰釉泛白而且欠红调,浅黄釉…     

Reported food intake and distribution of body fat: a repeated cross-sectional study

Background  

Body mass, as well as distribution of body fat, are predictors of both diabetes and cardiovascular disease. In Northern Sweden, despite a marked increase in average body mass, prevalence of diabetes was stagnant and myocardial infarctions decreased. A more favourable distribution of body fat is a possible contributing factor.     

Enterotoxigenic <Emphasis Type="Italic">Escherichia coli</Emphasis> strains bind bovine milk gangliosides in a ceramide-dependent process

Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) is the main infectious disease of newborn calves. The first step of infection involves bacterial attachment to the intestinal mucosa. This adhesion is mediated by fimbriae that recognize some glycoconjugates on the host cell surface, in particular, several gangliosides. Because milk also contains gangliosides, these have been suggested to serve as ligands for bacterial fimbriae and thus prevent the bacterial attachment to mucosa. The most relevant ETEC strains in calves, including those with K99 and F41 fimbriae, were assayed to determine whether they are able to bind gangliosides isolated from several stages of bovine lactation. Both GM3 and GD3, the main gangliosides of milk, were recognized by ETEC strains, although the different fimbriae showed diverse levels of affinity. Unexpectedly, the adhesion to colostral gangliosides was considerably weaker than that to gangliosides from the other stages of lactation. Because the carbohydrate moiety did not change and because differences in the percentages of unsaturated FA and sphingosine between colostrum and other stages were observed, we conclude that the differences in adhesion could be due to a different composition of the ganglioside caramide.     

Dietary fat and body weight control

The global obesity epidemic has heightened the debate about dietary factors contributing to weight gain. Media stories have promulgated the notion that obesity has increased despite reductions in dietary fat intake. Some have even speculated that lower dietary fat levels may be driving the rapid rise in weight gain within the population. A close examination of the science reveals a different picture and supports the hypothesis that dietary fat, within the context of the total dietary composition consumed by many populations, promotes obesity. Hence, dietary fat control is still an important strategy as part of an overall approach to body weight management in our modern environment. Dietary fat increases the energy density of foods. Abundant evidence from preclinical and clinical studies indicates that fat promotes excess energy intake and positive energy balance. Dietary fat does not promote its own oxidation in the body and is stored efficiently, promoting a positive fat balance. Thus, both the behavioral and metabolic responses to dietary fat increase the probability of positive energy balance and body fat gain. Restoring fat balance when consuming diets rich in fat requires increasing the size of the body fat mass, increasing physical activity, or reducing dietary fat intake. Numerous epidemiologic, preclinical, and controlled clinical studies have shown that body fat is positively associated with dietary fat intake and that dietary fat manipulation leads to appropriate changes in body fat mass. Finally, data from the National Weight Control Registry, a database of >3000 individuals who have successfully maintained a substantial weight loss, indicate that moderating dietary fat intake is a key strategy for long-term management of body weight.     

一步法纺HMLS提升断裂强力工艺探讨

根据我国《中国高新技术产品目录》,高模低缩(HMLS)涤纶工业长丝属于鼓励重点发展的产品,其优越性主要体现在用于制造子午胎骨架材料高模低缩涤纶帘子布的生产。用其生产的高模低缩涤纶     

Polar and Non-Polar Solvent Permeation Resistance of Blow-Molded Bottles of Polyethylene/Blends of Modified Polyamide and Polyamide 6 Clay Nanocomposite

Investigations on white spirit and acetone permeation resistance of modified polyamide and nylon 6 clay (MPANYC) blends and their corresponding polyethylene/MPANYC bottles were reported in this study. The white spirit and acetone permeation resistance of MPANYC sheets improve consistently with increasing NYC contents present in MPANYC resins after blending nylon 6 clay (NYC) in modified polyamide (MPA) resins. However, the order of barrier improvement of the PE/MPANYC and PE/NYC bottle specimens is not corresponding to the order of barrier improvement of the MPANYC and/or NYC barrier resins added in PE. The blow-molded PE/NYC bottle specimen exhibits similarly worse white spirit and acetone solvent permeation resistance as the PE bottle specimen, wherein no clearly formed NYC laminas but only dispersed NYC droplets or agglomerates were found on the fracture surfaces of the PE/NYC bottles. However, after blending optimum compositions of MPANYC in PE, the PE/MPANYC bottles with demarcated MPANYC laminas exhibit significantly better white spirit and acetone permeation resistance than the PE/MPA bottle, wherein the white spirit and acetone permeation rates of the PE/MPA₈NYC₁ bottle are about 1.3 and 1.4 times slower than those of the PE/MPA bottle, respectively. In order to understand these interesting barrier properties of PE/MPANYC and PE/NYC bottles, rheological, thermal, wide angle X-ray diffraction and morphological properties of the base MPANYC and NYC resins and their corresponding morphology present in the blow-molded bottles were investigated.     

Characterization of multiwall carbon nanotubes and influence of surfactant in the nanocomposite processing

Carbon nanotubes prepared by a classical CVD method with a nickel catalyst have been characterized, then used as conducting anisometric objects dispersed into a polymeric matrix. In a first part, these nanotubes are structurally characterized before and after heat treatments (HTT=1500, 2000, 2500 °C). Diffusion Raman experiments and diamagnetic susceptibility experiments demonstrated their limited graphitized structures.Then, in a second step, a well defined processing way to prepare nanocomposites with a standard epoxy resin is presented. In particular, the use or not of a non-ionic surfactant (Tergitol) to disperse these nanotubes is analyzed. The influence of nanotube contents is examined on the bulk nanocomposite density, the glass transition temperature of the nanocomposites, and the d.c. electrical conductivity behavior. These results demonstrated that the interfacial properties are playing a fundamental role. On one hand, the glass transition temperature is increasing with the nanotube content, and on the other hand, the percolation threshold is found for a rather high critical volumic concentration. Finally, it is demonstrated that a pure geometrical model is not sufficient to explain these behaviors and that a wrapping effect of the organic matrix around the nanotubes has to be considered.