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.     

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.     

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.     

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.     

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.     

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 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.     

可视化测定痕量甲醛的研究

摘 要：共振光散射(RLS)法是近年发展起来的新的分析测试技术,它具有简便快速,灵敏度高的特点,已用于痕量元素或物质的分析。本文基于一定条件下,在碱性溶液中甲醛能还原Ag+ 得到黄色银胶,使体系的RLS增强,从而建立起测量环境中痕量甲醛的RLS新方法。结果表明,新建方法测定甲醛的浓度线性范围为1.0?10-6?2.0?10-5 mol/L,检出限为1.0?10-7 mol/L,样品加标测定的回收率为96.26%? 103.32%。并且不同浓度的甲醛还原Ag+ 得到黄色银纳米粒子的颜色明显不同,基于此建立了一种可视化半定量测定痕量甲醛的新方法,新建方法简便快速,灵敏度高。用于环境水样、室内空气中甲醛的测定,结果满意。     

Kinetics of thermal decomposition of hexanitrohexaazaisowurtzitane

Thermal decomposition of hexanitrohexaazaisowurtzitane (HNIW) in the solid state and in solution was studied by thermogravimetry, manometry, optical microscopy, and IR spectroscopy. The kinetics of the reaction in the solid state is described by the first-order equation of autocatalysis. The rate constants and activation parameters of HNIW thermal decomposition in the solid state and solution were determined. The content of N₂ amounts to approximately half of the gaseous products of HNIW thermolysis. The thermolysis of HNIW and its burning are accompanied by the formation of a condensed residue. During these processes, five of six nitro groups of the HNIW molecule are removed, and one NO₂ group remains in the residue, which contains amino groups and no C−H bonds. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 815–821, May, 2000.     

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.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Pulse polarographic determination of the complexation capacity of various organic phosphonates of heavy metals with the aid of design of experiments

This study presents the determination of the complexation capacity of phosphonates (ATMP, EDTMP, and DTPMP) by differential pulse polarography. All of them are non-volatile, stable in water samples, and resistant to hydrolysis. Therefore, their decomposition rate in natural water is low. The metal complexation capacity of these phosphonates was detected for cobalt, copper, and zinc ions. DTPMP is the best of the investigated chelating agents for these three metal ions.Owing to the environmental fate of aminocarboxylates, these were often replaced by phosphonates. Therefore, we compared NTA and EDTA with ATMP and EDTMP according to their Zn-CC and could find out approximately four times higher complexation of zinc ions by phosphonates than by aminocarboxylates.Furthermore, the interaction between phosphonates and the influence of iron ions on the Zn-CC were investigated by chemometric means. The design of experiments indicated no significant interaction in phosphonate mixtures but significant influence of iron ions. Thus, the complexation capacity of a mixture of ATMP, EDTMP, and DTPMP can be calculated by the addition of several individual Zn-CC of the phosphonates according to their percentage in the mixture. A similar calculation is impossible in the presence of iron ions.     

Spectroelectrochemical Properties of Some Polymers of Polythiophene Series

The spectroelectrochemical behavior in situ of some polymers of polythiophene series, polybithiophene (PBT) and poly-3-phenylthiophene (P3PhT), is studied in the processes of anodic and cathodic doping. It is confirmed that in the case of PBT and P3PhT, the cathodic evolution of the absorption spectra, which is characteristic of the cathodic doping process, occurs in solutions of tetrabutylammonium salts, but not in solutions of lithium salts. It is shown that polymers of a more complicated structure than that of PBT, e.g. P3PhT, feature additional absorption bands, as compared to PBT, which demonstrates a single absorption band. Moreover, in the case of P3PhT, two color transitions can be observed by sight in the process of doping-undoping, unlike the single transition observed in the case of PBT and most other electron-conducting polymers. On the basis of quantum-mechanical calculations, an assumption is made that such a behavior of P3PhT is due to the decrease of the local symmetry of polythiophene chain in the presence of a bulky substituent, which causes the activation of the transitions in the electronic spectra that are forbidden in more symmetrical structures.__________Translated from Elektrokhimiya, Vol. 41, No. 6, 2005, pp. 755–765.Original Russian Text Copyright © 2005 by Erenburg, Popov, Semenikhin.     

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.     

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。     

刺五加不同部位微量元素含量的分析测定

用硝酸、高氯酸混合酸消解样品,采用原子吸收光谱法,测定了刺五加根、茎、叶中Ca、Cu、Mg、Fe、Zn、K、Mn、Na等8种矿物质元素的含量,并对其结果进行了分析比较,以此研究了这几种金属元素在刺五加体内的分布。结果显示,各元素在实验范周内,线性关系良好,加标回收率在99％～109．6％之间,相对标准偏差为0．2％～1．8％;刺五加中不同部位的这8种元素间存在显著差异,根中各元素含量由高到低顺序为Ca,Mg,K,Fe,Na,Mn,Zn,Cu,其叶中的含量以K为高,而且各部位其它元素含量均较高。从微量元素的角度分析,刺五加的根、茎、叶均有一定的应用价值。     

腹腔镜手术联合药物治疗子宫内膜异位症的临床疗效分析

目的评价腹腔镜手术联合药物治疗子宫内膜异位症的临床疗效。方法选取东莞市第三人民医院于2015年1月至2017年1月收治的150例子宫内膜异位症患者,按随机盲选法分为两组,对照组75例给予腹腔镜手术治疗,观察组75例给予腹腔镜手术联合药物治疗,对比两组临床治疗效果。结果在治疗总有效率方面,观察组为94.67%,明显要比对照组的70.67%高,两组数据差异有统计学意义(P<0.05)。在不良反应发生率方面,观察组为5.33%,明显要比对照组的22.67%低,两组数据差异有统计学意义(P<0.05)。结论对于子宫内膜异位症患者,采取腹腔镜手术联合药物进行治疗,具备显著疗效,能够降低不良反应发生率,因此,值得在临床中采纳及应用。     

Thermochemistry of dissolution of sodium alkylsulfonates

The effect of temperature on the solubility of ionic surfactants was interpreted in terms of standard enthalpy and entropy of dissolution at reference temperature by considering the change in the heat capacity. The significant value of the latter quantity causes the curvature of the function logarithm of equilibrium constant (or solubility) vs. the reciprocal thermodynamic temperature. The solubility data for several sodium n-alkylsulfonates, published by Saito, Moroi, and Matuura, were interpreted by nonlinear regression analysis. It was found that both the enthalpy and entropy of dissolution decrease with the chain length. The heat capacity increases in the course of the dissolution process.