The Mixed Compounds of Calcium and Titanium With Tiron. I

A pH-spectrophotometric study of the Ti-tiron complex in the presence of Ca ions revealed the existence of mixed compounds of Ca-Ti-tiron. These could account for the interference of Ca in the determination of Ti by tiron. The formation of these mixed compounds under varying concentrations of components and at varying pH is discussed. The absorbance of the Ti-tiron was likewise studied in the presence of many colorless salt solutions, but the behavior of Ca was found to be unique. Use was made of the color of the mixed compounds of Ca-Ti-tiron to develop a method for the identification of small amounts of Ca in the presence of large quantities of many common salts.     

Effect of cooling rate on melt-crystallization of random propylene-ethylene and propylene-1-butene copolymers

Summary  The effect of variation of the rate of cooling on melt-crystallization of random copolymers of isotactic polypropylene with low amount of either ethylene or 1-butene is evaluated using X-ray techniques, atomic force microscopy, and calorimetry. Slow non-isothermal melt-crystallization mainly results in formation of monoclinic α-crystals of lamellar geometry. The presence of comonomers leads to a decrease of the degree of crystallinity, and of the thickness of lamellae. These changes are proportional to the concentration of co-units, and are more distinct in propylene-ethylene copolymers. Rapid cooling of propylene-1-butene copolymers leads to formation of non-lamellar mesomorphic domains, independent of the concentration of co-units within the investigated range of concentrations. In quenched propylene-ethylene copolymers, in contrast, the formation of mesomorphic structure partially is replaced by formation of monoclinic α-crystals of still non-lamellar geometry.     

Capillarity and water repellency of fabrics

A method of determining the contact angle of wetting of fibres in the capillaries of fabrics is proposed. A theoretical calculation of the angles of wetting of cotton and blended fabric fibres with water was performed in the condition of formation of a uniform hydrocarbon film on the surface of the fibres. The real contact angles of wetting of water-repellent fabrics were determined; they differ from the angles of wetting of uniform hydrocarbon films by 10-12% due to the presence of hydrophilic molecules of the emulsifiers in the modifying film.     

Effectiveness of operation of a DVKh-1000 mixer in the production of electrical periclase powders

Conclusions The DVKh-1000 mixer provides a completely satisfactory degree of uniformity of the chemical and grain size compositions of the material in production of electrical periclase powders. The optimum conditions are obtained with a weight of charged material of 1.4–1.6 tons and a mixing time of 20 min. The coefficient of averaging is 0.60–0.80 for the content of the impurity CaO and 0.64–0.86 for the grain size composition.With a change in the requirements of the standard for grain size composition of electrical periclase powders and also with a change in the method of their production the optimum operating conditions of the mixer may be established on the basis of special additional investigations.The use of methods of geometrization of quality criteria in mineral resources for evaluation of the degree of uniformity of a material in mixing made it possible to establish an effect consisting of the fact that such properties as plasticity and viscosity characteristics of the aggregate condition of a substance (solid, liquid, gaseous) are revealed in the geometric features of the change in quality criteria and physical and technical characteristics of the pulverized and bulk material. This effect explains the existence of some limit of uniformity in mixing of materials with a different degree of variability of its quality criteria. The numerical value of this limit is determined by the physical properties of the material and the design features of the mixing equipment. For the investigated material and type of mixer this limit is 0.06–0.08%.Translated from Ogneupory, No. 8, pp. 41–45, August, 1988.     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.     

Study of the criteria for radial distribution of components in cross sections of yarn by computer modeling

Experiments were conducted on computer modeling of the cross section of two-component yarn. The sensitivity of each of the criteria of radial distribution of the fibres in the cross section of yarn made from a blend of chemical fibres was determined. The area of application of each criterion was determined with consideration of the results of the computer experiments.     

几种萘酞菁硅配合物的光动力效应的研究

研究了7种轴向配位的萘酞菁硅配合物的激发态性质、产生单重态氧的能力及对几种氨基酸的光敏氧化能力.研究表明,对于相同浓度的不同配合物来说,随着轴向配位基团推电子能力的逐渐增强,激发三重态寿命降低,产生单重态氧的能力逐渐下降,而产生单重态氧的能力是光敏氧化氨基酸反应速率的决定因素,因此,其光敏氧化氨基酸的一级反应速率常数逐渐减小.     

化工原理传质单元操作工程研究的方法论

基于对化工原理课程中各传质单元操作工程研究方法的分析,笔者论述了各传质单元操作的研究方法,在相平衡描述、传质速率描述、物料衡算、极限处理法和技术经济性分析等几个方面存在着共同的特征。掌握这一共性特征,对于整体上把握传质单元操作的教学内容和教学方法,具有认识论和方法论上的意义。     

串联攻坚战斗部前级爆轰场对后级影响分析

为了研究串联战斗部前级爆轰场作用下,后级随进子弹炸药安全性及其速度降的大小,建立了一维冲击波传播理论分析模型,由图解法得到了后级装药的初始压力。通过与炸药引爆阈值压力比较,判断了后级装药的安全性。根据动量守恒,得到了后级子弹的速度降表达式。进行了串联装药的数值计算,得到一定隔板厚度情况下后级装药受到的冲击压力和后级子弹速度降,计算得到的后级子弹变形情况与试验结果相吻合。     

International Conference on Chemical Fibres. Chemical Fibres: Present and Future. Look at the Next Century. Part 2

The trends in the development of chemical fibre production processes are analyzed and the general characteristics of the change in their manufacture as a function of the fundamental determining factors are found. The characteristics of chemical fibre production processes and subsequent treatments are examined and the possibilities of optimizing and intensifying existing technologies and improving the properties of the fibres by physical and chemical modification are demonstrated. Fibre formation in nature and industry is compared. The possibilities of creating new fibre production technologies, using methods of bionics in particular, are demonstrated. The development of the raw-material base for chemical fibres, including finding new sources of raw materials, is evaluated. The development of alternative principles for spinning chemical fibres and new technologies and types of fibres should be expected: production of fibres of the Lyocell type by dissolving cellulose in organic solvents will solve the problem of development of hydrated cellulose fibres, which is important due to the gradual decrease in production of viscose fibres; creation of fibres based on synthetic polypeptides of the fibroin type and production of chemical fibres @mdash; close analogs of natural silk and cobwebs; use of the principles of bionics based on synthesis of regular block-copolymers of defined structure which allow regulating the properties of the fibres by their self-organization. Use of water as a solvent will allow creating @ldquo;environmentally clean@rdquo; fibre production processes. The development of polyvinyl alcohol fibre production is due to the creation of new methods of synthesis of polyvinyl alcohol. Water is also the basic component of solvents of synthetic polypeptides. New, alternative raw-material sources based on synthesis of monomers from atmospheric components (carbon dioxide, nitrogen) and water, biotechnological processes, growth of highly productive cellulose-containing crops, and others are becoming important for ensuring increasing chemical fibre production volumes.     

New approaches to the integrated synthesis of flexible automated chemical engineering systems

The problems of optimizing the design and operational (control) variables during the integrated design of flexible automated complexes of chemical engineering process (CEP)—automated control systems (ACS) under conditions of the uncertainty of physicochemical, engineering, and economic initial data have been formalized. The selection of the best available version of a flexible automated complex is performed by means of the pairwise comparison of alternative versions of automated complexes using criteria that take into account both the quality of the manufactured products and the characteristics of energy and resource saving, on one hand, and the quality of transient processes in the ACS, on the other hand. A two-stage problem of stoichastic optimization of flexible automated complexes with hard and soft constraints has been stated, and a new approach to its solution has been proposed. An example of the integrated design of a flexible continuous process of azo pigments synthesis and a system of the optimum stabilization of its conditions in the presence of an interval uncertainty of the kinetic coefficients of the chemical reaction and individual engineering variables has been shown.     

悬浮态TiO_2光催化降解腐殖酸的影响因素研究

在悬浮态TiO2光催化体系中,探讨了光催化氧化降解腐殖酸的规律,考察了催化剂投加量、腐殖酸溶液初始浓度、初始pH值、光强、反应时间等因素对腐殖酸去除效果的影响。结果表明,光催化氧化法降解腐殖酸的效率比直接光解法有显著提高,腐殖酸的去除率从34.73%增加到65.61%(反应时间为3 h);TOC的去除率也大幅度提高,直接光解反应对TOC几乎无去除作用,而光催化氧化对TOC的去除率达37.5%;腐殖酸的初始浓度增加,初始pH值降低,光强增大,光照时间延长均能提高腐殖酸的降解率,其中pH值和光强的影响较为显著。另外,催化剂的投加量存在一个最佳值。     

Surface structure of folded-chain crystals of poly(R-3-hydroxybutyrate) of different chain length

The structure of the crystalline-amorphous interface of poly(R-3-hydroxybutyrate) (PHB) of different molar mass is evaluated by analysis of the rigid amorphous fraction and by analysis of the degree of reversible melting and crystallization. The rigid amorphous fraction of low-molar-mass PHB of 5 kDa is only 5-10%, and at best half of that of high-molar-mass PHB of almost 500 kDa, despite identical crystallinity. This result is paralleled by observation of distinctly larger degree of reversible melting and crystallization in PHB of high molar mass. The larger rigid amorphous fraction and higher degree of reversible melting and crystallization in PHB of high molar mass, consistently and independently, prove enhanced covalent coupling of crystals and amorphous structure, and/or de-coupling of segments of macromolecules which traverse between phases, respectively. The distinct isolation of crystals in PHB of low molar mass is discussed in terms of absence of wide loops/folds, long-chain cilia, and tie-molecules.     

Alkaline hydrolysis of ethyl acrylate–acrylonitrile–divinylbenzene copolymer beads

This article deals with the alkaline hydrolysis of ethyl acrylate–acrylonitrile–divinylbenzene copolymer beads. Chemical changes during hydrolysis were evaluated by means of determination of total weight exchange capacity and of infrared spectroscopy. The influence of reaction temperature, concentration of the hydrolytic agent, degree of copolymers crosslinking as well as the influence of particle size upon the rate of hydrolysis were studied as a function of time. The mathematical and statistical calculations of experimental data were carried out. With respect to time dependence of hydrolysis of the copolymer functional groups, the average values of reaction rate constants as well as the values of assumed diffusion coefficients were calculated. The analysis is based on partial linearization of experimental results by means of semilogarithmic transformation. The empirical relations expressing dependences of reaction rate constants and of diffusion coefficients on conditions of hydrolysis were determined.     

Influence of capillary condensation on heat and mass transfer in the grain of a Fischer-Tropsch synthesis catalyst

A mathematical model of heat and mass transfer processes in the grain of the Fischer-Tropsch synthesis catalyst is presented that takes into account the effect of the capillary condensation of the products of the synthesis in the pores of the catalyst. The influence of capillary condensation on the processes of the diffusion transfer of heat and mass in the catalyst grain is analyzed using the proposed model. Dependences of the efficiency factor of the grain on the pressure and temperature of the process and the partial pressure of various components of a mixture are presented. The possibility of determining the optimum pressure and temperature of carrying out the process for the catalyst of a certain structure is shown.     

Scientific foundations of preparation and technologies of production of the catalysts of reforming of gasoline fractions: Development of the process technology

The article summarizes the results of development of the scientific foundations of preparation of the catalysts, and of the experimental development works on creation of the new technologies of their production with the use of physical models, which were previously created on the basis of fundamental research. The results of the adoption of the new production technologies of the reforming catalysts of the PR series at the domestic plants are presented. The adoption consisted in creation and approbation of the fundamentally new technologies of production of the aluminum hydroxide (AHO) by means of the continuous method, modification of AHO by the elements of IV group, plasticization and forming of AHO in the production of the support, application of H₂PtCl₆ using the reactions of the ligand substitution of C⁻ by the functional groups of the support, and reduction and activation of the catalyst, which provide the optimal chemical com- position. Their operation during the 15-year period is analyzed. The reasons of high selectivity (up to 90%) of the new catalysts are found; the new technologies of the combined processing of mixture of C₃-C₄ alkanes with C₅₊ are developed and tested for the production of the high-octane catalysts with selectivity approaching 100%. The main effect of the C₅₊ yield increase of the end products is achieved by the transformation of the C₃-C₄ alkanes into the more high-molecular aromatic hydrocarbons. New processes of the combined processing of the mixtures of C₃-C₄ and gasoline fractions can be considered to be an alternative technology, which solves the important task of broadening the source of raw materials of the motor fuels by the inclusion of the C₃-C₄ alkanes of little value into the processing.     

On the dynamics of drop acceleration at the early stage of velocity relaxation in a shock wave

The early stage of velocity relaxation of a water drop in a flow behind a shock wave under conditions of drop deformation and breakup is studied experimentally. The aerodynamic drag of the drop is measured on the basis of the dynamics of motion of its leading edge, and a strong dependence of the drag on the observation time is demonstrated. These data are compared with the drag obtained on the basis of the dynamics of the center of mass of the drop. The drag of the center of mass is shown to be comparable with the drag of a solid sphere and to be substantially smaller than the value determined from the leading edge motion. A possible physical mechanism of this effect is proposed, which is based on the delay of the beginning of motion of the center of mass of the drop, owing to certain specific features of stabilization of external and internal flows at the early stage of velocity relaxation. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 2, pp. 101–108, March–April, 2008.     

Estimating the degree of perfection of the crystalline structure of kaolin

Atechnique of estimating the structural instability of substances is developed on the basis of studies on hydrothermal modification of clay ores. It is suggested that estimation of the degree of perfection of the crystalline structure of mono- and poly-mineral clays be performed on the basis of a determination of the strength of individual junctions in suspensions.     

Anisotropy of the conductivity of carbon fibre materials

The effect of the structure of graphitized fibre materials (fabric, nonwoven, tricot), degree of compression, and direction of current flow on their resistivity was investigated. It was shown that there are local minima of the resistivity of these materials as a function of the direction of current flow. The resistivity decreases linearly as a function of the apparent bulk density of the graphitized fibre material. The value of the resistivity of carbon-fibre composites is close to the resistivity of a maximally compressed material. It was found that systems design methods can be used to optimize the engineering creation of the electrodes of fuel elements made of carbon-carbon porous composites.     

纳米TiO_2光催化降解工业污水的因素权重评价

对于光催化氧化降解处理工业污水的工艺条件或因素的权重评价是达到优良处理效果的关键性技术之一。将模糊数学中的模糊综合评判法与信息工程学中的熵权结合而建立地熵权模糊综合评判法来对光催化氧化降解过程的影响因素权重进行评价,结果表明,该种方法的评价结果和参考文献中的评价结果基本吻合。因此,熵权模糊综合评判法在光催化降解因素分析中具有一定的可靠性和可参考价值。