埋藏哈密翼龙化石的雅丹风化的光谱分析——以大海道2号水源地雅丹为例

新疆哈密地区翼龙化石具有极高的科学研究价值.哈密翼龙动物群主要埋藏在早白垩世湖相地层形成的雅丹中,富集在风暴沉积层.化石一旦暴露地表,就会发生不同程度的自然风化破碎,尤其是见水或受潮后风化更为严重.哈密大海道2号水源地附近的雅丹底部由于地下水和间歇性地表水的作用,发生了严重的盐碱析出导致的强烈风化现象,造成雅丹下部剥落...     

具有幂零局部子群的有限群

一个有限非幂零群G称为PN-群,如果NC(P)是幂零的,对于每个素数p和每个满足PZ∞(G)的非正规子群p-子群P.本文将给出可解PN-群的结构和一些特征定理.     

Synthesis of well-defined soluble polystyrene supports: Impact of polymer chain on grafted organotin reagent activity

The synthesis of well-defined soluble polystyrene supports bearing tin hydride functionalities has been achieved in two steps. First, a precursor was prepared by copolymerization of styrene and acetoxystyrene using atom transfer radical polymerization. Prior any modification, this precursor was fully characterized to check its structure. Then in a second part, tin hydride functions were introduced by a four step process. The chemical modification was monitored by IR and ¹H NMR spectroscopies. The soluble support was also characterized by triple detection size exclusion chromatography at each step. Two families of supports were synthesized by varying the molecular weight and the degree of functionalization. The effectiveness of these tin hydride supports was tested through the reduction of 6-bromohexene and compared with the small counterpart Bu₃SnH. Measurements of rate constant for hydrogen transfer were also reported.     

Synthesis,characterization and molecular weight studies of certain soluble poly(3-alkylthiophene) conducting polymers

Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized by constant potential electrolysis. The resultant polymers were characterized by cyclic voltammetry, ultraviolet spectroscopy, thermogravimetric analysis and differential scanning calorimetry. Molecular weights were studied with gel permeation chromatography on solutions of the polymers in toluene. Surface properties were investigated by scanning electron microscopy. Substituent groups lengths have been found to strongly influence the electronic properties of the resultant polymers. Poly(3-hexylthiophene) has shown the highest conductivity, with the highest degree of polymerization. The conductivity and the degree of polymerization values decrease as the substituent chain length increases.H.B. Mark Jr.: deseased     

烃源岩可溶烃、热解烃、总有机碳含量与光谱指数相关性研究

烃源岩的可溶烃含量(S1)、热解烃含量(S2)和总有机碳含量(TOC)是进行烃源岩研究和评价的重要指标,以往主要通过实验室分析方法获得,时效性得不到保证。为了探讨野外快速测量这些指标的可行性,采集了乌兹别克斯坦克孜勒库姆地块10件烃源岩样品,运用地面ASD光谱仪和碳硫分析仪,分别测定了样品的可见光-近红外-短波红外(Vis-NIR-SWIR)反射光谱和S1, S2和TOC含量参数。运用光谱拟合微分,获得了上述样品反射光谱的一阶导数、二价导数等微分数据;并运用线性回归方程拟合和拟合结果统计分析,研究了这些数据同S1, S2和TOC含量之间的相关性。结果表明:烃源岩S1含量与原始光谱、光谱一阶导数、二阶导数分别有1 973, 511和239个波段相关,相关系数绝对值最大值分别为0.612, 0.823和0.889,相关性程度分别为弱、较强、极强;烃源岩S2含量与原始光谱、光谱一阶导数、二阶导数分别有2, 144和205个波段相关,相关系数绝对值最大值分别为0.561, 0.867和0.926,相关性程度分别为弱、较强、极强;烃源岩TOC含量与原始光谱无相关性,与光谱一阶导数、二阶导数分别有18、 180个波段相关,相关系数绝对值最大值分别为0.882和0.879,相关性都极强。此外, S1含量与光谱二阶导数的2 012 nm波段拟合优度最高,达0.790;S2含量与光谱二阶导数的363 nm波段拟合优度最高,达0.858;TOC含量与光谱一阶导数的2 480 nm波段拟合优度最高,达0.777。结果说明,利用可见光-近红外-短波红外反射光谱反演烃源岩S1, S2和TOC含量具有比较好的效果。为研究野外烃源岩的原位检测奠定了重要的基础。     

Tamely uniform orders

The following two results are proven.

(i) Let G be a finitely generated torsion-free linear group. If every torsion-free section of G is an R-group, then G is soluble of finite rank. Conversely, if G has finite rank, then it has a subgroup of finite index, in which every torsion-free section is an R-group.

Let G be a finitely generated torsion-free soluble group. If in every torsion-free section of G the normalizer of each isolated subgroup is isolated, then G has finite rank. Conversely, if G has finite rank, then it has a subgroup K of finite index such that in every torsion-free section of K the normalizer of each isolated subgroup is isolated.     

A systematic insight into fouling propensity of soluble microbial products in membrane bioreactors based on hydrophobic interaction and size exclusion

Soluble microbial products (SMPs) contained in membrane bioreactor (MBR) supernatant have been proved to be main foulants. To obtain a comprehensive understanding of the fouling potential of SMPs on the basis of both hydrophilic/hydrophobic properties and molecular size, MBR supernatant of a pilot-scaled system treating municipal wastewater was partitioned into different hydrophilic/hydrophobic fractions by DAX-8 resins, with joint size partition of hydrophilic fraction also undertaken. A series of stirred dead-end filtration tests were conducted to investigate the flux decline. Hydrophilic fraction was found the dominant foulant responsible for flux deterioration, which was mainly attributed to the subclass of molecular weight above 100 kDa. The molecular weight distribution and atomic force microscopy images indicated that large molecules in hydrophilic fraction plugged the membrane pores. The backwash tests showed the flux decline caused by hydrophilic fraction was much less recoverable by hydraulic cleaning. It can be inferred that steric factor, i.e. size exclusion was the primary cause in the initial stage of fouling, while the role of hydrophobic interaction was of less significance. Additional modeling work indicates that the main fouling mechanism was complete blocking, further confirming the predominance of size exclusion contributing to membrane fouling by SMPs in MBR supernatant.     

Colorless poly(ether-imide)s deriving from 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride(BPADA) and aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

A series of poly(ether-imide)s (III) characterized by colorless, highly solubility was synthesized from 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride(BPADA) and various fluorinated aromatic diamines (I_a-h) in DMAc via polycondensation to form poly(amic acid) (II), followed by chemical (C) and thermal (H) imidization. These polymers had inherent viscosities ranging from 0.60 to 1.3 dL/g. These polyimides were highly soluble in a variety of organic solvent such as amide-type, ether-type and chlorinated solvents. Moreover, these poly(ether-imide) films were almost colorless, with an ultraviolet-visible absorption cutoff wavelength below 390 nm and low b* value (a yellowness index) of 4.6-18.0. The III series showed strength tensile of 72-101 MPa, elongation at break of 11-25%, initial modulus of 1.5-2.0 GPa. The glass transition temperature (T_g) of III_a-h were in the range of 202-267 °C, and the decomposition temperature above 493 °C and left 40-65% char yield at 800 °C in nitrogen. They had the lower dielectric constants of 3.39-3.72 (1 MHz) and moisture absorptions in the range of 0.11-0.40%.     

Novel organosoluble and colorless poly(ether imide)s based on 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride and trifluoromethyl-substituted aromatic bis(ether amine)s

A series of novel fluorinated poly(ether imide)s (IV) having inherent viscosities of 0.70-1.08 dL/g were prepared from 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride (I) and various trifluoromethyl (CF₃)-substituted aromatic bis(ether amine)s II_a-g by a standard two-step process with thermal and chemical imidization of poly(amic acid) precursors. These poly(ether imide)s showed excellent solubility in many organic solvents and could be solution-cast into transparent, flexible, and tough films. These films were essentially colorless, with an ultraviolet-visible absorption edge of 375-380 nm and a very low b^∗ value (a yellowness index) of 5.5-7.3. They also showed good thermal stability with glass-transition temperatures of 207-269 °C, 10% weight loss temperatures in excess of 474 °C, and char yields at 800 °C in nitrogen more than 62%. In comparison with analogous V series poly(ether imide)s without the -CF₃ substituents, the IV series polymers showed better solubility, lower color intensity, and lower dielectric constants.     

离子液体和水: 构建高效绿色的纳米粒子催化体系

金属纳米粒子-保护剂-绿色溶剂体系, 因其高效、绿色, 且易实现反应产物和催化体系分离而备受关注. 新型的纳米粒子催化体系设计空间大, 通过设计纳米粒子、保护剂、功能化溶剂可以实现不同的反应和工艺要求, 也更符合低毒、高效可循环等绿色化学的理念. 本文结合作者课题组设计的纳米粒子-保护剂-绿色溶剂催化体系实现的一系列反应, 回顾了这个绿色的新催化体系发展的过程.