改性淀粉絮凝剂的制备及絮凝性能研究

以淀粉和丙烯酰胺为主要原料,采用反相乳液聚合方法制备淀粉接枝共聚物,考察了诸因素对反应过程的影响,并对产物絮凝性能进行了研究.结果显示:该絮凝剂能使污水中颗粒悬浮物絮凝成大颗粒沉淀,达到较好的絮凝效果.     

基于非对称场流分离技术研究直链/支链比值对小米淀粉退化行为的影响

退化是淀粉糊化后分子链重排的过程,为了探究直链/支链比值对淀粉退化的影响,本文采用碱性甘油超声提取小米淀粉中直链淀粉,通过非对称场流分离技术、差示扫描量热法、傅里叶变换红外光谱、扫描电子显微镜、X线衍射法,对3种不同直链/支链比值的小米淀粉的颗粒形貌、晶体结构、结晶度、糊化特性、退化行为进行了表征.实验结果表明,碱性甘...     

新型水溶性深度氧化玉米淀粉的制备及氧化机理

研究一种新型的多羧基水溶性氧化玉米淀粉的制备方法, 最佳制备条件为: 适量的自制催化剂, 以氧气为氧化剂, NaOH用量为21 g, 反应温度100 ℃, 反应时间3.0h. 在该条件下制备的氧化淀粉羧基含量为3.60%.采用X射线衍射分析（XRD）、 扫描电子显微镜（SEM）、 红外光谱分析（IR）以及羧基、 羰基含量的化学分析法等对氧化机理进行了探讨.     

The cytotoxicity of eosinophil cationic protein/ribonuclease 3 on eukaryotic cell lines takes place through its aggregation on the cell membrane

Human eosinophil cationic protein (ECP)/ ribonuclease 3 (RNase 3) is a protein secreted from the secondary granules of activated eosinophils. Specific properties of ECP contribute to its cytotoxic activities associated with defense mechanisms. In this work the ECP cytotoxic activity on eukaryotic cell lines is analyzed. The ECP effects begin with its binding and aggregation to the cell surface, altering the cell membrane permeability and modifying the cell ionic equilibrium. No internalization of the protein is observed. These signals induce cell-specific morphological and biochemical changes such as chromatin condensation, reversion of membrane asymmetry, reactive oxygen species production and activation of caspase-3-like activity and, eventually, cell death. However, the ribonuclease activity component of ECP is not involved in this process as no RNA degradation is observed. In summary, the cytotoxic effect of ECP is attained through a mechanism different from that of other cytotoxic RNases and may be related with the ECP accumulation associated with the inflammatory processes, in which eosinophils are present. Received 26 October 2007; accepted 23 November 2007     

Starch-binding domains in the post-genome era

Starch belongs to the most abundant biopolymers on Earth. As a source of energy, starch is degraded by a large number of various amylolytic enzymes. However, only about 10% of them are capable of binding and degrading raw starch. These enzymes usually possess a distinct sequence-structural module, the so-called starchbinding domain (SBD). In general, all carbohydrate-binding modules (CBMs) have been classified into the CBM families. In this sequence-based classification the individual types of SBDs have been placed into seven CBM families: CBM20, CBM21, CBM25, CBM26, CBM34, CBM41 and CBM45. The family CBM20, known also as a classical C-terminal SBD of microbial amylases, is the most thoroughly studied. The three-dimensional structures have already been determined by X-ray crystallography or nuclear magnetic resonance for SBDs from five CBM families (20, 25, 26, 34 and 41), and the structure of the CBM21 has been modelled. Despite differences among the amino acid sequences, the fold of a distorted β-barrel seems to be conserved together with a similar way of substrate binding (mainly stacking interactions between aromatic residues and glucose rings). SBDs have recently been discovered in many non-amylolytic proteins. These may, for example, have regulatory functions in starch metabolism in plants or glycogen metabolism in mammals. SBDs have also found practical uses. Received 25 May 2006; received after revision 26 June 2006; accepted 3 August 2006     

异丁烯阳离子聚合引发体系CH_3COO-t-Bu/BCl_3/CH_2Cl_2的研究

采用傅立叶红外光谱和紫外光谱的技术,研究了在极性溶剂CH_2Cl_2中异丁烯阳离子聚合的引发体系乙酸叔丁酯/三氧化硼/二氧甲烷中,各组分间的作用及组分配比对活性中心结构的影响,发现Lewis酸与酯的比值不同,体系中存在络合竞争,以至存在一种或两种(或以上)活性中心;当Lewis酸与酯之比很小时,活性中心失活,并由此探讨其聚合机理。     

新型变性淀粉的实验研究

在高温、高压条件下,含有盐酸或硫酸时用尿素或其他单体处理淀粉,得到用于瓦楞纸板制造时的快速粘合剂产品。对淀粉的变性和一些操作参数的关系作了讨论。     

HDPE固相接枝丙烯酸的研究

以过氧化苯甲酰（ＢＰＯ）为引发剂、二甲苯为界面剂，研究丙烯酸（ＡＡ）在粉料高密度聚乙烯（ＨＤＰＥ）上的固相接枝反应．红外光谱证实了该接枝反应。Ｘ光衍射发现接枝后的ＨＤＰＥ结晶度下降不多，表明接核反应发生在ＨＤＰＥ的无定区域和晶区表面或晶区缺陷上。实验还发现，随着引发剂用量、ＨＤＰＥ颗粒度的增加，反应温度的升高，单体／聚合物比增加，接枝率提高。本研究制得的ＨＤＰＥ—ｇ—ＡＡ，其接枝率可高达１５．９２％。     

丝素蛋白纤维的接枝聚合（Ⅱ）──无引发剂存在时丝素蛋白纤维接枝烯类单体

研究了无引发剂存在时丝素蛋白纤维与烯类单体的接枝聚合反应．与四价铈盐引发的接枝聚合相比，无外加引发剂存在时的接枝聚合，可以获取高得多的接枝率和单体的接技效率．这种接枝聚合方法是丝素蛋白纤维的一种更为有效的改性方法．接枝０．６％２－羟基－４－丙烯酰氧二苯酮（ＨＡＯＢＰ）的丝素蛋白纤维，其热稳定性及紫外稳定性均得到了显著的改善，但力学性能没有下降．     

生淀粉糖化酶产生菌1—16的选育研究

对生淀粉糖化酶产生菌黑曲霉进行了初步诱变选育，得到一株具有较高生淀粉糖化酶生产能力的１－１６菌株，其生淀粉糖化酶平均发酵单位较原菌株提高了３９％。