白炭黑

白炭黑是由二氧化硅构成的一种白色微粒,能代替炭黑作橡胶补强剂而得名。也能应用到其它工业部门,因此它是一种重要的工业原料。     

大豆油生物柴油低温流动性能影响的研究

以大豆油为原料采用碱催化酯交换法合成生物柴油,测定了其酸值、游离甘油、总甘油、灰分、黏度和磷含量等指标。实验表明,共存的甲醇、水分和甘油酯对生物柴油的低温流动性能影响极少,饱和脂肪酸甲酯的同时析出对生物柴油低温流动性能起关键作用。考察了5种柴油降凝剂、0号和20号柴油以及乙醇对生物柴油低温流动性能的影响。0号柴油有效地改善生物柴油黏度,但对其低温流动性能影响不大。20号柴油和乙醇能显著降低生物柴油的凝点、倾点、冷滤点和黏度。其中3种降凝剂有效降低生物柴油的凝点和倾点,1种降凝剂能小幅度改善冷滤点,5种降凝剂都能使生物柴油的黏度小幅上升。     

基于原子表面的蛋白质水合自由能预测模型

提出了一种计算蛋白质水合自由能的简化模型（SAWSA 2）.模型把蛋白质分子中的原子分为20种不同的原子类型,通过每类原子的溶剂可及化表面以及相应的溶剂化参数,就可以得到分子的水合自由能.不同原子类型的溶剂化参数通过110个蛋白质分子水合自由能拟合得到,水合自由能的标准值采用了基于求解Possion-Boltzmann方程（PB）以及分子表面计算（SA） 相结合的方法.采用得到的模型,预测了20个蛋白质分子的水合自由能,预测值的相对值和绝对值都能和PB/SA的计算值很好地吻合,大大优于两种已报导的水合自由能模型.     

辅助热稳定剂对钡锌复合体系性能的影响

探讨异辛酸钡和异辛酸锌复合体系对聚氯乙烯(PVC)透明性能的影响, 以此为基础考察辅助热稳定剂水滑石(LDH)、 亚磷酸酯和β-二酮3种复合体系对PVC透明性能的影响. 结果表明, LDH能显著改善PVC的各项热稳定性能, 并且与Ba/Zn体系产生了显著的协同效应. 3种不同的辅助热稳定剂都能有效改善PVC的初期热稳定性能.     

黄精属中两种高异黄酮的理论计算研究

采用密度泛函理论M06-2x/6-311G(d,p)方法对黄精中两种高异黄酮进行结构优化和单点能计算。计算键解离能、电离势、质子离解能、质子亲和能、电子转移能。从三种自由基清除机制的能量比较来看,HAT是解释其自由基清除活性的主要机制。计算气相中两种高异黄酮的HOMO、LUMO、能隙、电负性、硬度与软度等分子描述符,化合物1和化合物2的HOMO与LUMO图相似,HOMO主要集中在A环,表现出A环较强的电子给予能力。LUMO主要集中在B环与C环,该区域得电子能力较强。绘制两种分子的静电势和福井函数图以考察其活性位点。     

SARS冠状病毒主要蛋白酶二聚体静电和疏水效应的研究

从三种冠状病毒主要蛋白酶SARS 3CL, HCoV 3CL和TGEC 3CL蛋白酶结构出发,着重研究了三种蛋白酶二聚体单体之间的静电和疏水相互作用.用连续介质模型有限差分方法计算得到三种蛋白二聚体界面处的静电势,发现三种蛋白酶单体和单体之间静电势分布具有明显的互补性,三种蛋白酶二聚体单体之间具有相同的静电相互作用能.用溶剂可及表面积模型分析了分子表面积及疏水性,发现三种蛋白酶具有相同的疏水分布,其中SARS 3CL蛋白酶疏水率为74%,驱动其单体聚合成二聚体.对三种蛋白酶的去溶剂化能疏水项的计算表明,三种蛋白酶二聚体单体之间具有相似的疏水相互作用能.     

γ-环糊精和波尼松龙的相互作用分子动力学模拟和自由能计算

运用分子动力学（Molecular dynamics,MD）和MM—PBSA（molecular mechanics／Poisson Boltzmann surfaeearea）相结合的方法预测了γ-环糊精（γ-cyclodextrin,γ-CD）和波尼松龙的包结模式．在MD模拟过程中,波尼松龙分别采用A环和D环两种取向从γ-CD大口端进入其空腔．在MD轨迹采样基础上,采用高效MM—PBSA方法计算了两种取向的包结自由能．结果表明,计算包结自由能值和实验包结自由能值非常吻合．进一步分析各个能量项,发现范德华相互作用能为包结的主要驱动力．通过比较两种取向的包结自由能大小,预测D环取向为优势包结模式．     

MnZSM-5催化剂上NH3-SCR反应机理的研究

通过密度泛函理论（DFT）对Mn/ZSM-5催化剂上NH3-SCR反应机理进行了理论研究。一种为气态NO直接参与反应的E-R机理,NO分子与[NH2]反应生成中间体[NH2NO],该反应路径的能垒为43.35 kcal/mol;另一种为吸附态NO参与反应的L-H机理,[NO]与[NH3]反应生成[NH2NO],该反应路径的能垒为44.73 kcal/mol。因两种机理的反应能垒相差不大,因此在一定温度下遵循两种机理的反应皆能进行。     

化学教学中的比喻

比喻在化学教学中的作用比喻就是打比仿,原是一种修辞手法,运用到化学教学中,成为教学的一种表述方法。准确而较贴切地运用比喻,一般能起到如下的作用:1、能使所描述的事物更加生动形象。     

含锆碳硅陶瓷先驱体的半经验理论研究

采用PM6方法对添加了配体Zr(AcAc)4,Zr(NH(C2H5))4,ZrCp2Cl2,ZrCp2ClH形成的16种含锆碳硅陶瓷先驱体(PZCS)和PCS(10)的几何结构、电子属性、反应能进行了系统的理论研究,结果表明:(1)大体积的Zr(AcAc)4带来的的空间效应并未过多的影响Si—Zr键的键长;(2)从单配体衍生物到对应的多配体衍生物HOMO-LUMO能隙趋向于减小,配体Zr(NH(C2H5))4得到的衍生物的能隙下降幅度最大.ZrCp2Cl2得到的衍生物的能隙比对应的ZrCp2ClH的能隙要大;(3)16种PZCS的反应能均为负值,随配体数的增加,Zr(NH(C2H5))4的衍生物的反应能减小,而其他三种配体的衍生物的反应能增大.     

气相色谱仪双毛细管柱双检测器技术在毒物检测中的应用

利用双毛细管柱双检测器技术建立常见毒物的检验方法, 并对其进行定性分析. 样品进样后通过VSOS装置同时进入两根不同极性的毛细管柱, 经分离后到达两个不同选择性的检测器. 利用VSOS装置可对毒物进行较好的分离、定性. 该方法可对常见毒物进行准确定性.     

Confirmation of okadaic acid, dinophysistoxin-1 and dinophysistoxin-2 in shellfish as their anthrylmethyl derivatives using UV radiation

A rapid and simple method for confirmation of the diarrhetic shellfish poisons (DSP): okadaic acid (OA), dinophysistoxin-1 (DTX-1) and dinophysistoxin-2 (DTX-2) using fluorescence detection following derivatization with 9-chloromethylanthracene, has been established as an alternate to LC/MS. Exposure of the anthrylmethyl derivatives of OA, DTX-1 and DTX-2 to near UV light (300-400 nm) resulted in the loss of these compounds to below detection limits within 30 min, with a concurrent appearance of two additional compounds. Based on the mass spectral evidence, we propose that these newly formed compounds are the decarboxylation products of the derivatized diarrhetic shellfish poisons. UV radiation is, therefore, proposed as a rapid and simple confirmation technique for these DSP in mussel samples.     

多氯取代对二苯并呋喃结构和电荷分布影响的量子化学研究

多氯取代对二苯并呋喃结构和电荷分布影响的量子化学研究苏忠民，盛连喜，赵宝忠（东北师范大学化学系，长春１３００２４）王东仁，李金昶（东北师范大学测试中心，长春，１３００２４）关键词：多氯代二苯并呋喃，电荷分布，量子化学计算本文采用量子化学方法，以多氯二...     

Kinetics of olefin copolymerization with heterogeneous Ziegler-Natta catalysts

The kinetics of the ethylene/1-hexene copolymerization reaction with a Ti-based Ziegler-Natta catalyst has been studied. Kinetic analysis established the existence of several populations of active centers in the catalyst. The centers differ in two aspects: their ability to incorporate α-olefin units into copolymer chains (i.e., their reactivity ratios) and the average molecular weights of the polymer chains they produce. The centers of different populations are formed at different rates and have different kinetic stabilities. As a consequence, both the molecular weight distributions of the copolymers and their compositional distributions are relatively broad and change with in time. Two kinds of catalyst poisons were found. The poisons of the first type, arylalkoxysilanes, preferentially deactivate the centers which have the highest ability to copolymerize α-olefins with ethylene. These poisons decrease the average α-olefin content in the copolymers and the fraction of their olefin-rich components. The poisons of the second type, conjugated dienes, preferentially deactivate the centers which have the lowest ability to copolymerize α-olefins with ethylene. These poisons significantly increase the content of the olefin-rich components in the copolymers.     

Analysis of low levels of oxygen, carbon monoxide, and carbon dioxide in polyolefin feed streams using a pulsed discharge detector and two PLOT columns

A gas chromatography (GC) method is developed for rapid analysis of polyolefin feed streams for the catalyst poisons CO, CO(2), and O(2). The method uses an HP MoleSieve column in parallel with a CP-PoraPLOT Q column and a pulsed discharge detector (PDD). Detection limits for each of the potential poisons are between 50 and 250 ppb. For a 10-ppm standard, the precision of the method was +/- 4.2% for oxygen, +/- 7.8% for carbon dioxide, and +/- 2.0% for carbon monoxide. In addition to the polyolefin feed stream, nitrogen and hydrogen feed streams are also analyzed. In each case, sampling is observed to be a critical issue, with air contamination of the sample cylinder often the limiting step in determining the true level of oxygen. It is also noted that large amounts of argon are present in the standards when nitrogen is used as a balance gas. Because the trace oxygen peak partly coelutes with the larger argon peak, it is suggested that helium be used as the balance gas for all standards. This general experimental arrangement should be effective when applied to feed streams for other polymers as well.     

Detection of illicit material using neutron activation: weakness and solutions

Poisoning the illicit materials by a neutron absorber leads to false detection when the detection is relied on combined thermal neutron activation and fast neutron activation to identify the elements of interest. The use of adjacent transmission thermal neutron detector for verifying the presence of neutron poisons and to trigger an alarm was investigated experimentally and using MCNP calculations. The illicit material of high hydrogen content will affect the detector response in the presence or absence of poisons.     

The topopyrones poison human DNA topoisomerases I and II

The topopyrones are fungal natural products shown previously to act as poisons of human DNA topoisomerase I. Recent total syntheses of the four known naturally occurring members of this class of compounds have enabled more detailed biochemical characterization. Presently it is shown that in addition to topoisomerase I, topopyrones A-D also act as poisons of human DNA topoisomerase II. The topopyrones thus represent a rare example of molecules capable of interacting effectively with more than one DNA topoisomerase.     

Transition metal-catalyzed dehydrocoupling of group 13-group 15 Lewis acid-base adducts

Transition metal-catalyzed dehydrocoupling is a relatively new method for main group element-element bond formation, providing a facile alternative to salt metathesis processes. Lewis acid-base adducts of Groups 13 and 15 can undergo dehydrocoupling with both early and late transition metals and complexes thereof to yield rings, chains and macromolecules based on a framework of alternating B-N or B-P atoms. Evidence is also provided for Group 13 hydrides acting as poisons towards heterogeneous dehydrocoupling catalysts.     

Development,optimization and application of an analytical methodology by ultra performance liquid chromatography–tandem mass spectrometry for determination of amanitins in urine and liver samples

Amanitins, highly toxic cyclopeptides isolated from various Amanita species, are the most potent poisons accounting for the hazardous effects on intestinal epithelium cells and hepatocytes, and probably the sole cause of fatal human poisoning.