Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

自由基聚合中平均聚合度的学习

自由基聚合是《高分子化学》课程的重要一章 ,其中 ,平均聚合度是自由基聚合微观动力学的重要研究内容。正确理解其概念 ,掌握各种数学表达式的涵义 ,对高分子化学的学习十分有益 ,本文对不同终止和链转移情况下平均聚合度的表述方法进行了讨论     

Study of the thermodynamics of adsorption of hydrolyzed modified polyacrylnitrile

The thermodynamics of adsorption has been studied of hydrolyzed modified polyacrylnitrile (HMP) in water solutions with a concentration ranging from 0.25 g/l to 2.00 g/l on bleached sulphate and unbleached and bleached sulphite celluloses at temperatures of 0, 20, 40, and 60 C.It has been established that with the rise in temperature, the amount of adsorbed polymer —(HMP) decreases. The values of the enthalpy change are negative and show a linear decrease with the increase in the amount of adsorbed polymer. The adsorption equilibrium is defined by the logarithmic isotherm of Tjumkin, valid for uniform heterogeneous surfaces.With the increase in the amount of adsorbed HMP the values of the entropy change become negative and linearly decrease. A compensation effect has been noticed which results from the simultaneous action of the entropy and energy factors.The values of the change of the chemical potential for the three types of cellulose are negative and linearly decrease with the increase in the amount of adsorbed HMP and with the rise in temperature.     

Investigation of the influence of pressure on the combustion of Alpagut lignite

This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Çorum of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25, 50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by effluent gas analysis method. The changes in the amounts of consumed oxygen, evolved carbon oxides as well as variations in the temperature were assessed. The combustion efficiency and effectiveness of lignite was evaluated in terms of thermal features, from the viewpoint of reaction kinetics and by the computation of instantaneous fuel consumption at critical points. It was seen that combustion of lignite tended to turn from a steady profile to a considerably rapid one with increase in pressure, proving to be highly sensitive to the applied pressure level. Also, different levels of pressure resulted in distinctive combustion behavior not only from the view of thermal characteristics, but also in terms of reaction kinetics.     

Thermodynamic parameters of solvation of nonelectrolytes in aqueous solutions of amides of carboxylic acids

Interaction and reorganization contributions to solvation enthalpies of nonelectrolytes in aqueous solutions of amides of carboxylic acids with different degree of N-substitution and N-methylpyrrolidone are calculated. The data are discussed using structurally thermodynamic characteristics of water-amide systems obtained by us previously. It is found that the type of concentration dependence of the solvation enthalpy of nonelectrolytes in all solutions investigated is determined by the type of reorganization component. It is shown that the highest solvation exothermicity of nonelectrolytes in water is due to the lowest value of the reorganization contribution in spite of that nonelectrolytes interact weaker with water than with non aqueous components.     

Synthesis of a Pair of Derivatives of N-Methylpyrrole Polyamide

A pair of derivatives of tetrameric N-methylpyrrole polyamide were synthesized in order to develop a new method for the study of interaction of the polyamide derivatives with DNA. Indole acetic acid and nicotinic acid were introduced to the polyamide in the synthesized compound, which showed an expected red shift in the UV spectrum. These compounds may function as a potential tool in the detection of the polyamide binding to DNA.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Features of the mechanism of oxidative dehydrodimerization of propynol

Analysis of kinetic regularities for the propynol oxidative coupling under the action of cupric salts in pyridine and in the presence of a buffer is undertaken. The reaction mechanism, including the formation of Cu(I) acetylides, is considered.     

多肽树枝状大分子合成的研究进展

多肽树枝状大分子具有不同于链状多肽和其它树枝状大分子的物理化学性质,在化学、生物、医学等领域中有广泛应用。本文综述了近年来所报道的多肽树枝状大分子的合成进展。     

成都市城市绿地土壤理化性质研究

对成都市绿地土壤的理化性质进行了研究,并与郊区的土壤作了比较.结果显示,该市绿地土壤的pH明显高于市郊,而有机质含量和总硫含量则低于市郊.     

溶剂化效应对6-亚甲基环戊二烯酮与HCN的反应机理影响的理论研究

在B3LYP/6-311+G**计算水平上, 采用导体极化连续模型研究了溶剂化效应对6-亚甲基环戊二烯酮与HCN反应生成主要产物b类酸的反应机理的影响. 计算结果表明, 在溶剂中的反应机理与在气相中的反应机理一致. 溶剂化效应使反应路径中各驻点的自由能降低, 稳定化了各物质. 溶液中的活化自由能与气相相比也有所降低, 反应更容易发生, 其中CC进攻方式的活化自由能降低得更多.     

青海湖区河谷灌丛主要植物微量元素含量特征

采集青海湖地区沙柳河河谷灌丛14种主要植物，采用AAS分析了其中7种微量元素含量。结果表明，元素Cu、Mn、Co含量有较大的植物种问差异，7种微量元素中Se含量最小，Fe含量最大。元素Mn和Fe、Co、Ni之间都具有极显著的正相关性，即相互之间具有协同性作用。     

Application of exploratory data analysis for the characterization of tubular wells of the North of Brazil

Roraima is located in the extreme North of Brazil, in the Western Amazon Region. The groundwater has an important role in the public supply of potable water on the Roraima State. The objective of this work is the application of PCA (Principal Component Analysis) and HCA (Hierarchical Cluster Analysis) for the characterisation of tubular wells of the Roraima State, as regards physical–chemical composition of water. The parameters analyzed in laboratory were the following ones: pH, electric conductivity, Total Hardness, Total Alkalinity, Bicarbonate, Calcium, Potassium, Magnesium, Nitrate, Chloride, Total Iron. The physical–chemical analyses, were carried out during the months of September and October 2000 (winter, period of rains). The laboratory analysis was performed using classical methods (titrimetry and uv–visible spectroscopy), the samples were processed in agreement with the Standard Methods for Examination of Water and Wastewater.The physical–chemical analyses, were accomplished in September and October 2000. In physical–chemical terms, the groundwater samples analyzed do not indicate any restriction to human consumption and the two chemometric methods of exploratory data analysis: PCA and HCA are efficient for the discrimination of bicarbonated (tubular wells locateds in the South of the Roraima State) and not bicarbonated (tubular wells locateds in the North of Roraima) groundwater.     

二硫代氨基甲酸盐的除油机理及pH值对其除油性能的影响

絮体;二硫代氨基甲酸盐的除油机理及pH值对其除油性能的影响     

The use of surfactants in the cleaning of works of art

Surfactants have been historically used for cleaning artifacts, but it was only in the last decades that serendipitous approaches were replaced by research in the field of soft matter and colloid science. Surfactants are components of nanostructured fluids, which were assessed for the removal of soil and aged coatings from paintings and are fundamental in processes that range from the inclusion of grime in micelles to the swelling and dewetting of polymer layers. Intriguing aspects involve the synthesis and use of biodegradable and self-cleavable surfactants, and the confinement of nanostructured fluids in gels, which boost the selectiveness of cleaning interventions. The performances of these advanced systems surpass those of traditional cleaning materials such as solvent blends and thickeners. The most important results are here reviewed and future perspectives given. Besides granting the transfer of cultural heritage to future generations, advanced cleaning materials are relevant to transversal fields, such as detergency, cosmetics, and drug delivery.     

Chemical Programming of the Domain of Existence of Liquid Crystals

This work illustrates how enthalpy and entropy changes responsible for successive phase transitions of cyanobiphenyl‐based liquid crystals can be combined to give cohesive free energy densities. These new parameters are able to rationalize and quantify the demixing of the melting and clearing processes that occur in thermotropic liquid crystals. Minor structural variations at the molecular level can be understood as pressure increments that alter either the melting or clearing temperatures in a predictable way. This assessment of microsegregation operating in amphiphilic molecules paves the way for the chemical programming of the domain of existence of liquid‐crystalline phases.     

压力对塔里木原油四组分热解性能的影响

压力对深层油藏原油热化学过程的影响尚存在较大争议,为研究其在油藏原油热解成气过程中的作用机理,我们在450℃、5~40 MPa压力下对塔里木原油四组分(饱和分、芳香分、胶质和沥青质)进行了封闭体系的热解实验,通过气相色谱(GC)和气相色谱/质谱(GC/MS)分别对原油四组分热解反应的气体产物及饱和分热解过程的液态产物进行了分析。结果表明,在450℃、24 h及不同压力下,沥青质热解产气率高于胶质、芳香分和饱和分;四组分的气相热解产物中,C1的产率明显高于C2~C5组分。增大压力抑制沥青质、胶质及芳香分的热解产气过程而促进饱和分的热解产气过程。随压力的增大,饱和分热解的液态产物的主峰组分碳数先减小,再增大。压力低于20 MPa时,饱和分热解过程中以裂解反应为主;高于30 MPa时,增大压力有利于缩合反应。研究结果可为认识深层油藏原油的稳定程度及天然气的成因提供一定的理论参考。     

The influence of the addition of electrolytes on the degree of dispersion of silver iodide hydrosol

The changes in the degree of dispersion of AgI hydrosols produced by reaction of AgNO₃ and KI with the addition of other electrolytes (1–60 min after addition of AgNO₃ to KI) were investigated by photometric methods. The results obtained suggest that in the process of rapid condensation (caused by a sudden increase in concentration to a value considerably higher than the critical one) colloidal particles do not form by continuous growth of individual nuclei but through disaggregation of loose and amorphous, i. e. thermodynamically unstable clusters of previously formed embryos. This disaggregation process, termed protopeptization by the authors in order to underline its analogy with the peptization process, increases in magnitude with the strengthening adsorption of potential-determining ions (protopeptizing agents) by the particles formed in the precipitation process.     

无胶筛分毛细管电泳分析几百个碱基对核酸的条件优化

通过正交设计实验综合分析了内充羟丙基甲基纤维素（ＨＰＭＣ）无胶筛分毛细管电泳中的分离场强、ＨＰＭＣ浓度、柱长度和柱内径对核酸分离的影响。结果表明,柱长度越长、柱内径越小、分离场强越小,分离效果越好。考虑实际情况,为能在短时间内使几百个碱基对的核酸得到有效分离,一般选择３７ｃｍ×７５μｍｉ．ｄ．的涂壁毛细管、柱内质量浓度为８ｇ／Ｌ的ＨＰＭＣ、场强为３２４Ｖ／ｃｍ的条件,并在此种条件下分析了ＡｐｏＢ１００基因的低浓度聚合酶链式反应（ＰＣＲ）扩增产物（７１０ｂｐ）。     

Enthalpy of dilution of tetra-n-butylammonium bromide in mixtures of water and N-methylacetamide

The enthalpy of dilution of tetra-n-butylammonium bromide in mixtures of water and N-methylacetamide has been measured from approximately 0.1 to 1.0m at 35°C. The mole fraction of water in the solvent varied from 0.250 to 0.969. The results are strikingly nonlinear in the mole fraction of water. As the mole fraction of water varies from 0 to 0.7, there is only a small change in the enthalpy of dilution. At higher mole fractions of water, the excess enthalpy rises sharply to the unusually high values found in water. This indicates that the unusually high values of excess enthalpy associated with hydrophobic bonding in water are destroyed by relatively small amounts of N-methylacetamide.Taken in part from the Ph.D. thesis of J. S. Falcone, Jr., University of Delaware, Newark, Delaware, June 1972.