“恒速反应”热重分析法用于测定非等温热分解的动力学参数(英)

利用高解析热重分析仪提出了一种简单可靠的方法,用以测定固体非等温热分解反应的动力学参数．以EVA的第1阶段热裂解为例,说明测定表观活化能、频率因子以及确定最合适反应机理函数的实验和数据处理方法．所得结果与传统热失重法数据一致．     

Protein folding and degradation in bacteria: to degrade or not to degrade? That is the question

In Escherichia coli protein quality control is carried out by a protein network, comprising chaperones and proteases. Central to this network are two protein families, the AAA+ and the Hsp70 family. The major Hsp70 chaperone, DnaK, efficiently prevents protein aggregation and supports the refolding of damaged proteins. In a special case, DnaK, together with the assistance of the AAA+ protein ClpB, can also refold aggregated proteins. Other Hsp70 systems have more specialized functions in the cell, for instance HscA appears to be involved in the assembly of Fe/S proteins. In contrast to ClpB, many AAA+ proteins associate with a peptidase to form proteolytic machines which remove irreversibly damaged proteins from the cellular pool. The AAA+ component of these proteolytic machines drives protein degradation. They are required not only for recognition of the substrate but also for substrate unfolding and translocation into the proteolytic chamber. In many cases, specific adaptor proteins modify the substrate binding properties of AAA+ proteins. While chaperones and proteases do not appear to directly cooperate with each other, both systems appear to be necessary for proper functioning of the cell and can, at least in part, substitute for one another. RID="*" ID="*"Corresponding author.     

两性纤维素接枝共聚物CGAD水溶液的性质

制备了羧甲基纤维素钠接枝丙烯酰胺和甲基丙烯酸二甲胺基乙酯盐酸盐共聚物（ＣＧＡＤ）,用红外光谱和元素分析对其组成进行了分析．用浊度法测定了它的溶解性,实验发现ＣＧＡＤ具有两性聚合物的特征,有等电点存在,且与组成有关．用粘度法测定了其水溶液的粘度行为,发现温度升高或溶液老化都使溶液的特性粘度降低,外加盐浓度在一定浓度时特性粘度出现最大值．此外,ＣＧＡＤ水溶液在纤维素酶的存在下能够降解．     

生物降解材料—聚乙交酯医用纤维的研究

以乙醇酸为原料，合成α－乙交酯单体，进而再聚合成生物降解聚合物聚乙交酯（ＰＧＡ）。对聚合物进行纺丝成形，获得ＰＧＡ纤维。应用红外光谱（ＩＲ）、差示扫描量热分析（ＤＳＣ）、热重分析（ＴＧＡ）和Ｘ－射线衍射法，研究聚乙交酯的结构和性能。通过对ＰＧＡ纤维的生体内外的降解试验，发现其降解速度随浸渍液的ｐＨ值的增加而增大，特别是在碱性介质中重量损失最为明显。ＰＧＡ纤维埋入ＳＤ大白鼠体内，对机体无毒性，组织反应极小，６０天后能被机体完全吸收，对机体具有良好的相容性。     

剪切与高温降解聚合物对水包油乳状液稳定性的影响

研究了聚合物3530S及其降解后的聚合物对水包油乳状液稳定性的影响,用界面剪切粘度和zeta电位考察了水包油乳状液的稳定机理。研究发现,热氧降解后聚合物的界面活性升高,降解后的聚合物使乳状液的稳定性变差,水包油乳状液的稳定性主要由界面膜强度和油珠表面的zeta电位决定。     

白腐菌的筛选及对松木片木素和树脂的脱除

为评价从野外筛选得到的白腐菌对造纸原料马尾松的木素降解和树脂脱除能力,将带菌样本经室内平板初筛及平板变色反应复筛,得到了20株纯白腐菌菌株,并对变色系数最小的一株菌株G进行松木片固体接种试验,测定3、5、7、9天后松木片的木素、树脂降解情况.结果表明,随着培养时间的延长,松木片失重率逐渐增大,K lason木素和总木素含量逐渐降低,二氯甲烷抽提物脱除率逐渐增大.表面扫描电镜(SEM)照片表明,接种白腐菌的木片细胞壁上产生了明显的腐朽沟槽现象;切片断面显微结构显示,在细胞壁及胞间层有菌丝出现.     

EM菌技术降解长春师范学院人工湖富营养化水质的研究

利用有效微生物EM(Effective Microorganisms)菌对长春师范学院人工湖水进行治理,结果表明:有效微生物EM菌可使水质中的COD、氨氮值含量降低;随着时间的增加及有机生态菌投放数量的增多,水质中的COD、氨氮含量明显降低,湖水水质得到进一步净化。     

STUDIES ON SURFACE CHARACTERIZATION AND ECOMATERIAL SHEET DEGRADATION OF BASALT FIBERS BY PLASMA TREATMENTS AND WOOD FIBERS

1.INTRODUCTIONDue to the fact that it is difficult to recover for many composites, developing naturally degradable ecocomposites has received increasing attention among scientists [1-4]. Basalt fibers serves as a reinforcement for a wide range of applications such as heat-insulation, resistance combustion, soundproofing. Their advantages include no carcinogenic effect, environmentally friendly, flexible, good temperature resistance and heating insulation property[5-8]. They were regarded …     

废水中铁离子对漆酶催化降解2,4-二氯苯酚的影响

探讨了水中铁离子对固定化漆酶和自由漆酶催化去除水中2,4-二氯苯酚反应的影响。结果表明,Fe²⁺和Fe³⁺离子对于自由漆酶催化去除2,4-二氯苯酚的反应均表现出一定程度的抑制作用,但对固定化漆酶降解2,4-二氯苯酚的影响要小,表明经过固定化之后,由于受到固定化载体的保护作用,酶的稳定性明显增加。     

基于Copula的车轮Gamma退化过程

通过Gamma随机过程描述机车轮缘与滚动圆直径的磨耗过程,研究了运用Copula函数和四阶矩方法计算轮缘退化与滚动圆直径退化的相关可靠性方法,通过动力学软件仿真得到列车不同阶段的动力学指标.研究了镟修周期为20万km的车轮退化过程的可靠性及车轮直径退化过程的灵敏度,利用Monte Carlo仿真(MCS)验证了该方法的正确性.结果表明:镟修周期为 20万km时车轮达到预期寿命的可靠性高,基于Copula函数相关失效退化模型计算的可靠性高于独立失效模型计算的可靠性,轮径退化可靠性模型的灵敏度研究说明镟修过程中应该要选取对轮径削减较少的方案.