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.     

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.     

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.     

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。     

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.     

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.     

Transport properties of anion-exchange membranes: Effect of the formation of complexes

Electroconductivity and diffusion permeability of heterogeneous anion-exchange membranes MA-40 and MA-41 are studied in solutions containing copper, nickel, and zinc cations. The composition of species present in the contacting solution is calculated on the basis of conditions of equilibrium and material balance with allowance made for the tendency of these cations to form complexes. It is shown that the reason for the electroconductivity of MA-40 increasing in dilute solutions of transition metal chlorides is the complexing between these cations and functional groups and the resultant increase in the overall positive charge of the polymer matrix. The complexing with ions of copper and zinc in the electromembrane phase reduces the mobility of chloride ions, thus lowering the membranes’ electroconductivity with increasing concentration of equilibrium solutions. The membranes are characterized using a method of determination of the transport properties and structure of the membranes. The method is applied for the first time to the complexing co-ions, with allowance made for variations in their charge and composition.     

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.     

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.     

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.     

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.     

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。     

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.     

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。     

Evaluation of radiostability of some steroid derivatives

The effect of ionising radiation (15-100 kGy) on the physico-chemical properties of 6 steroid derivatives in solid state (Hydrocortisone, Hydrocortisone acetate, Prednisolone, Prednisolone acetate, Dexamethasone and Fludrocortisone acetate) was studied by differential scanning calorimetry (DSC), differential thermal analysis (DTA), scanning electron microscopy (SEM), UV spectrophotometry, high-performance liquid chromatography (HPLC), X-ray powder diffraction and polarimetry. DSC and DTA results revealed that the irradiated compounds undergo phase transitions at lower temperatures, show lower melting points and lower enthalpy of the melting process their non-irradiated analogues. The results of HPLC measurements proved a loss in the active substance content after irradiation ranging from 0.5 to 2.88%. No significant effect of irradiation was detected by the UV spectrophotometry or polarimetry in the course of the UV spectrum, absorbancy or optical rotation, as well as in the SEM photographs and X-ray patterns. For some compounds studied a correlation was found between the irradiation dose and the shifts in DSC curves and the loss of content determined by the HPLC method. Similar, but not so much pronounced relations were established in or earlier studies of the derivatives of nitroimidazole and 1,4-dihydropyridine. In general the results have shown relatively high radiochemical stability of the compounds studied and have proved that the DSC method is a sensitive detector of irradiation-caused changes in drugs in solid phase. This revised version was published online in July 2006 with corrections to the Cover Date.     

荧光关联光谱在高分子单链研究中的应用

荧光关联光谱(fluorescence correlation spectroscopy,FCS)是一项用于研究体系动力学性质的统计光谱技术,随着它被引入材料与化学研究领域,近年来取得了大量全新的研究成果.该技术在高分子科学研究中也逐渐发挥出越来越大的作用,特别是在聚合物结构和动力学方面,这表明它在高分子领域的巨大潜力.本文将从FCS的基本原理、实验技巧以及在一些具有挑战性体系中的应用等方面展开,着重介绍它在高分子溶液,如聚电解质溶液、高分子混致不溶现象,以及不同的表界面体系中取得的新成果,展示FCS区别于其他传统技术的特点和优势.     

The review of versatile application of collagen

This review reports recent advances in the versatile application of collagen. Collagen materials have attracted great attention because they exhibit properties required in cosmetic preparations, in the biomedical field, and in the tanning industry leading to leather production. Herein, the structure and application of collagen are discussed in general, and detailed examples are also drawn from scientific literature and practical work. Copyright © 2016 John Wiley & Sons, Ltd.     

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.