PVC抗冲改性剂-MBS树脂的生产技术及市场前景

介绍了目前PVC抗冲改性剂MBS树脂的生产技术、技术进展和国内外MBS树脂的生产、消费现状，分析了我国MBS树脂的发展前景，由于PVC制品的迅速发展、抗冲改性剂产品结构的调整，以及MBS树脂的应用领域不断拓宽，MBS的需求将越来越大，同时对我国MBS树脂生产的发展提出了一些建议。     

MBS树脂胶含量对PC/MBS合金性能影响

PC/MBS合金熔体流动速率、拉伸强度、冲击强度和维卡软化温度的变化与MBS树脂中橡胶含量的多少相关。实验表明:MBS树脂中橡胶含量增加,合金的拉伸强度和维卡软化温度均降低,而冲击强度增大;实验中改变MBS树脂的树脂用量及其橡胶含量可以调节合金的流动性;橡胶含量为30%的MBS树脂可以很好地提高PC/MBS合金的冲击强度。     

PVC的抗冲改性剂——MBS树脂的开发和应用进展

作者通过赴日考察MBS树脂的体会,并结合自己多年来从事研究MBS树脂工作的实践,对MBS的开发应用和影响改进PVC性能的因素等进行了介绍,并对发展我国MBS树脂的方向提出了见解。     

PVC加工助剂MBS树脂的生产及市场前景

介绍了MBS树脂的生产技术，分析了中国MBS树脂的生产消费现状及发展前景，提出了发展中国MBS树脂生产的建议。     

MBS树脂的生产技术及市场前景

介绍了MBS树脂的生产技术及在PVC树脂中的应用,分析了国内外MBS树脂的生产消费现状及发展前景,提出了发展我国MBS树脂生产的一些建议。     

PVC抗冲改性剂-MBS树脂的生产技术及市场前景

介绍了PVC抗冲改性剂MBS树脂的生产技术现状及其进展,分析了国内外MBS树脂的生产消费现状及发展前景,提出了发展我国MBS树脂生产的一些建议。     

MBS树脂的生产和技术概况及其发展动态

简要介绍了PVC抗冲改性剂MBS树脂的国内外生产概况,详细阐述了MBS树脂的技术概况,并简要分析了国内有关MBS树脂生产、技术、市场和价格等方面的一些发展动态.     

MBS树脂的合成及表征

采用适时补皂、种子乳液聚合方法合成粒径大、分布窄的SBR胶乳。该胶乳接枝St—MMA共聚单体合成MBS树脂。研究了SBR粒径大小度其分布、MBS玻璃化转变温度以度其微观形态。实验结果表明，MBS树脂具有两个玻璃化转变温度，分别为MBS树脂的橡胶相和树脂相的玻璃化转变温度。且MBS树脂呈现规整的核壳结构。     

MBS树脂的生产技术研究进展

叙述了PVC冲击改性剂——MBS树脂的国内外生产技术状况,介绍了MBS树脂的主要生产工艺及系列产品的性能和用途,指出制备MBS树脂的新技术及其用于PET、PBT、PC等工程塑料方面的研究开发。     

MBS高聚物合金

用本体-悬浮法合成MBS树脂,对MBS树脂进行了表征。MBS与聚碳酸酯经熔融共混,得到有珍珠光泽的共混高聚物,改善了后者的应力开裂性质和流动性。     

Residual effects of phosphate fertilizers in relation to phosphate sorptivities of 27 soils

Three different parameters of the long term effects of phosphate fertilizers on perennial clover-based pastures were measured over 3–4 years in 27 experiments on acidic soils in an elevated region of eastern Australia. Recovery of fertilizer P was the difference between herbage P uptake in the presence of fertilizer and uptake in its absence, expressed as a % of the amount of P applied in the first year. Residual value was the size of the response to fertilizer P, applied in the first year, expressed as a percentage of the response to freshly applied P in the second and third years. Effectiveness was the product of the values of the Mitscherlich curvature and response parameters for each response curve, and residual effectiveness was relative to initial effectiveness. Soils varied widely in their P sorptivities, and represented Alfisols, Entisols, and Ultisols of basaltic, granitic and sedimentary origin. Mean P recoveries of 29% in the first year and 49% over 3 years, residual values of 84% in the second year and 60% in the third, and residual effectiveness of 77% in the second year and 47% in the third were high by most standards. Increasing P sorptivity tended to increase fertilizer effectiveness in the first year and residual value in the second year, but it depressed P recovery in the first year and residual effectiveness in later years. The long term effect of increasing P sorptivity on cumulative P recoveries tended to be negative at low to medium rates of fertilizer application and positive at high rates of application. There was a much smaller decline in residual values and effectiveness over the 3 or 4 years than there was in P recovery, and this was attributed to the beneficial effects of P on soil N fertility, via clover N fixation, and the subsequent growth of grasses in the phosphated treatments.     

Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.     

Changes in the Properties of Synthetic Fibres in Thermal Aging

Thermal aging of complex lavsan, nitron, and anid fibres and lavsan and nitron yarn was investigated in the temperature region above the glass transition temperature (120, 150, 180°C) in the free state and with shrinkage for up to 300 h. It was shown that thermal aging of chemical fibres in the general case includes periods of structural and thermochemical aging. The kinetic characteristics of thermal shrinkage of chemical fibres and yarn in the first period of thermal aging were investigated. An exponential curve of shrinkage in time was obtained and can be used to predict the behavior of fibres and yarn in the first period of aging in the free state. The kinetics of the change in the strength and relative elongation at break was investigated in prolonged thermal aging of chemical fibres and yarn in the free (with shrinkage) and fixed (without shrinkage) states. The exponential dependence of the change in the fibre breaking characteristics on the duration of heat treatment was demonstrated. The change in the properties in prolonged thermal aging in the free and fixed states in the first stage of aging takes place differently. With shrinkage, the strength decreases and the deformability increases as a result of relaxation phenomena in the first stage, followed by a symbatic decrease in the strength and deformability as a result of thermal degradation processes in the second stage. In heat treatment in the fixed state, the change in the mechanical properties in the first stage is slight, while the strength and deformability simultaneously decrease in time as a result of thermal aging in the second stage. The quantitative characteristics found can be used to predict the change in the mechanical properties of chemical fibres and yarn in conditions of prolonged exposure to heat.     

污泥生物炭中氮硫行为及环境效应研究进展

污泥生物炭中氮硫元素含量高,其氮硫行为和环境效应对全球气候变化的影响不容忽视。以往的研究中,研究者往往以富碳生物炭作为主要研究对象,关注碳对全球气候变化的行为和功效,而对氮硫元素的作用关注不够。本文从原始污泥基本性质到其热解过程,再到生物炭的老化,逐步对污泥生物炭整个生命周期内氮硫的行为及其环境效应研究进行综述,并对未来应注重开展的研究方向进行展望,为生物炭中氮硫元素固定、释放及与之关联的环境效应和温室气体排放控制研究提供理论基础。分析表明,污泥中氮元素含量普遍高于硫元素,且热解过程中氮比硫更容易转移至气相产物。氮硫元素随热解温度的增加,在三相产物中的分配都是炭中持续减少,油中先增后减,气中一直增加。高温（＞800℃）条件下,气相中的氮含量高于固相,而硫元素则仍然主要存在于固相中。污泥生物炭老化及其环境效应研究表明,污泥生物炭氮硫元素与土壤的相互作用及其温室效应问题在今后的研究中应引起重视。     

Distribution of cholesterol sulfate and its anabolic and catabolic enzymes in various rabbit tissues

Cholesterol sulfate (CS) recently has been shown to be involved in signal transduction pathway. To evaluate its functional significance, we determined the concentration of CS, and the specific activities of cholesterol sulfotransferase and CS sulfatase in various tissues of rabbit, and compared them with the concentration of sulfoglycolipids in rabbit tissues. CS was present in the epithelia and mucosa, but not in the tunica muscularis, of the digestive tract, trachea, uterine endometrium and uterine cervix. It was also present in lung, spleen, kidney, prostate, skin, hair, and nail at relatively high concentrations. Its concentration in the uterine endometrium was nine times higher in pseudopregnant rabbits than in nonpregnant rabbits because of activation of cholesterol sulfotransferase and inhibition of CS sulfatase in the pseudopregnant rabbits. Sulfoglycolipids were not detected in the uterine endometria of either nonpregnant-or pseudopregnant rabbits. However, sulfoglycolipids were detected at relatively high concentrations in the cerebrum, cerebellum, stomach, duodenum, jejunum, testis, and kidney of rabbits and thus the tissues in which both sulfolipids were detected were the gastrointestinal tract and kidney. In the digestive tract, the concentration of CS decreased in the order esophagus, stomach, duodenum, and jejunum, but that of sulfatide increased in the same order, indicating distribution of CS in the squamous epithelium. In addition, both CS and sulfatide were detected in the serum. On the other hand, CS sulfatase activity was detected in all tissues examined, even in hair, from which the enzyme was liberated by brief sonication, and its highest specific activity was deteted in the liver. The specific activity of cholesterol sulfotransferase varied among the tissues examined and was found to be significantly high in the esophageal epithelium and the uterine endometrium of pseudopregnant rabbit, indicating involvement of cholesterol sulfation in the formation of epithelium.     

Immunohistochemical Characteristics of the Human Carotid Body in the Antenatal and Postnatal Periods of Development

The evolutionary and ontogenetic development of the carotid body is still understudied. Research aimed at studying the comparative morphology of the organ at different periods in the individual development of various animal species should play a crucial role in understanding the physiology of the carotid body. However, despite more than two centuries of study, the human carotid body remains poorly understood. There are many knowledge gaps in particular related to the antenatal development of this structure. The aim of our work is to study the morphological and immunohistochemical characteristics of the human carotid body in the antenatal and postnatal periods of development. We investigated the human carotid bodies from 1 embryo, 20 fetuses and 13 adults of different ages using samples obtained at autopsy. Immunohistochemistry revealed expression of βIII-tubulin and tyrosine hydroxylase in the type I cells and nerve fibers at all periods of ontogenesis; synaptophysin and PGP9.5 in the type I cells in some of the antenatal cases and all of the postnatal cases; 200 kDa neurofilaments in nerve fibers in some of the antenatal cases and all of the postnatal cases; and GFAP and S100 in the type II cells and Schwann cells in some of the antenatal cases and all of the postnatal cases. A high level of tyrosine hydroxylase in the type I cells was a distinctive feature of the antenatal carotid bodies. On the contrary, in the type I cells of adults, the expression of tyrosine hydroxylase was significantly lower. Our data suggest that the human carotid body may perform an endocrine function in the antenatal period, while in the postnatal period of development, it loses this function and becomes a chemosensory organ.     

Solubility in and affinity for the bile salt micelle of plant sterols are important determinants of their intestinal absorption in rats

Intestinal absorption of various plant sterols was investigated in thoracic duct-cannulated normal rats. Lymphatic recovery was the highest in campesterol, intermediate in brassicasterol and sitosterol, and the lowest in stigmasterol and sitostanol. Higher solubility in the bile salt micelle was observed in sitosterol, campesterol, and sitostanol than in brassicasterol and stigmasterol. The solubility of the latter two sterols was extremely low. When the affinity of plant sterols for the bile salt micelle was compared in an in vitro model system, which assessed sterol transfer from the micellar to the oil phase, the transfer rate was the highest in brassicasterol, intermediate in campesterol and stigmasterol, and lowest in sitosterol and sitostanol. Although no significant correlations between lymphatic recovery of plant sterols and their micellar solubility or transfer rate from the bile salt micelle were observed, highly positive correlation was obtained between the lymphatic recovery and the multiplication value of the micellar solubility and the transfer rate. These observations strongly suggest that both solubility in and affinity for the bile salt micelle of plant sterols are important determinants of their intestinal absorption in rats.     

In vitro and in vivo evaluation of degradability and biocompatibility of poly(p-dioxanone) hemostatic clips for laparoscopic surgery

For the clinical application of biodegradable hemostatic surgical clips in laparoscopic surgery, it is necessary to determine their degradability and biocompatibility. Herein, in vitro and in vivo studies were undertaken to evaluate the degradability and biocompatibility of bioabsorbable clips made of poly(p-dioxanone). Changes in weight loss, pull-off force, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) of the poly(p-dioxanone) clips were determined after they were degraded in deionized water and phosphate buffer saline for the in vitro experiment and in laparoscopic models of bile duct ligation(BDL) and right gastroepiploic artery ligation(GEAL) using New Zealand white rabbits for the in vivo experiment. Changes in weight loss and pull-off force were greater in the in vivo experiment than the in vitro experiment. DSC showed the greatest variation in the degree of crystallinity of the clips degraded in deionized water. Stark differences in SEM were observed after 4 weeks of degradation both in vitro and in vivo. Furthermore, the cytocompatibility of the clips was considered satisfactory because the L929 cells could adhere to the clips and proliferate adequately in the presence of the clip extract. Biocompatibility was inferred based on the histological analysis of BDL and GEAL, no significant inflammatory responses were observed after 4 weeks of ligation.     

Intake of dietary fiber in the Central American isthmus: nutritional implications

Mean intakes of dietary fiber (DF) were estimated in the population of Central America and Panama, using the results of dietary surveys conducted in 1969 and 1986 both in rural and urban areas, as well as data on the DF content of foods as consumed in the region. Data on preschool children were also estimated. The results indicated that DF intake in urban areas is lower than that of rural areas, particularly in Costa Rica and Panama. In 1969, intake varied from 32g in El Salvador to 15g in Panama in urban areas, while in rural areas intake was from 45g in El Salvador to 13g in Panama. The foods which contributed most to the total intake in Guatemala, El Salvador and Honduras were tortillas and beans, while in Costa Rica and Panama, beans provided the largest intake. In preeschool children, intake was 12.5g in El Salvador and 5.4g in Costa Rica in 1969, which is the same tendency as that found for adults. From more recent data on food intake, it was found that DF intake had decreased in the rural areas of El Salvador, Honduras and Costa Rica, being between 4 and 9% in the first two countries and 12% in Costa Rica. In the urban area of the latter, from 1969 to 1986 a decrease in DF intake of around 20% has taken place.     

中国合成橡胶和精细化工的技术创新(上)

本文是王大全教授代表中国化工学会、中化化工科学技术总院 ,在 2 0 0 2年 4月 10～13日于北京召开 ,由中国工程院、中国科学院、中国科学技术协会联合主办的“中国近现代科学技术回顾与展望国际学术研讨会”上所作学术报告的部分内容。作者以亲自组织和参加研究开发成功的合成橡胶和精细化工有关项目成套技术的实践 ,总结了 2 0世纪 70年代以来中国合成橡胶和精细化工科技创新、原始创新和提高行业科技水平的经验。对加入WTO后如何加速提升我国化工科技创新和原始创新的能力 ,很有参考价值