Scrap of magnesia parts,the reasons for it,and means of reducing it

Conclusions The most common and characteristic forms of scrap of magnesia parts differing in form, dimensions, and composition are shown. These include deviations of the dimensions from the nominal, breaking off of the corners and edges, nonuniformity, welding together, spots, voids, fire cracks, spalls, and cracks of different origin.The reasons for formation of scrap were determined. The primary of them are the reduced quality of the raw material (chromite, magnesite) with a larger quantity of impurities containing limited silicon and calcium oxides, sometimes insufficient density, grain size, and completeness of hydration of the magnesite powders, nonconformity of the bunker, proportioning, mixing, and pressing equipment to the requirements of modern production of progressive high-quality refractories, the insufficiently high binding capacity of lignosulfonates, deviations in the quality of assembly and finishing of press equipment and automatic ejectors, of the car floor lining, and in firing conditions, a high variation in density of the green parts, and nonuniform heating and cooling in the volume of the parts and of the whole charge during firing. More than 50% of the total scrap of all forms is due to firing scrap of parts.The primary means of reducing or eliminating scrap of parts and simultaneously increasing their quality based on the reasons for formation of different forms of it were noted. These above all else, are increasing the volumes and improving and introduction of new methods of concentration of magnesite and chromite, a successive increase in the share of chrome concentrates, chromium-containing broken parts, and powders by firing of magnesite and caustic dust in the production of magnesia refractory parts as the result of a decrease in the share of commercial natural chromite and magnesite, the use in the production of parts of high-quality type PMSP-93 powder produced in shaft kilns and used as the charge for production of fused materials, the use of the prospect of processes for production of dense periclase powders uniform in chemical analysis from recovered caustic dust, replacement of obsolete mixing and press equipment by more modern, increasing the strength of green parts by above all else improving the binding properties of LST and increasing pressing pressure, forming of the taper of parts by the side plates of the die, improving the quality of assembly and increasing the reliability of functioning of press equipment and automatic ejectors, improving car floor linings, introduction of new methods and increasing the volumes of production of progressive unfired refractories in place of certain forms of fired parts, observation of all production parameters, and a relationship of the wages of labor to the quantity of scrap and the quality of refractories.Introduction of the new management system and the active work of the quality groups created will open up and lead to the action of unutilized reserves for reduction of scrap.Translated from Ogneupory, No. 2, pp. 31–38, February, 1989.     

Special Features Of Stabilization Of The Growth Process In Plasma-arc Growth Of Single Crystals Of Refractory Compounds From SHS Products

Problems of the stability of the growth process in growing single crystals of refractory compounds (carbides and bondes of transition metals) by the method of plasma-arc remelting are considered. The main reasons behind the loss of stability of the spatial configuration of the melt (a shift of the anode lock-on of the arc from the center of the molten pool, disturbance of the symmetry of the plasma jet, superheating of the melt) are considered. The effect of cyclic perturbations in the crystallization system that appear upon replenishment on the fluctuation of the energy characteristics of the arc, the temperature of the melt, and the displacements of the crystallization surface is described. It is established that the crystallization rate and the process of coarsening of the crystallites in the formation of a columnar structure in the ingot depend on the frequency of feeding new portions and on their mass.     

Investigation of conditions of spherulite formation in mixtures of crystalline and amorphous polymers

The supermolecular structure of mixtures of crystalline polymers (low pressure and high pressure polyethylene, isotactic polypropylene) with an amorphous polymer (atactic polypropylene) from the point of view of the influence of the amorphous component on the morphology of the crystalline component has been investigated. The criterion of changes in the morphological state of larger supermolecular formations was the microscopic image of the samples obtained with an optical microscope, both between crossed nicols and in phase contrast. It has been established that the formation of typical spherulites depends on the amount of admixture of the amorphous polymer and also on the treatment of the samples. Upon crystallization in presence of a small amount of solvent (p-xylene), formation of typical spherulites of the crystalline component of the mixture can be observed while the same mixture in case of evaporation of the solvent presents a granulated refractive structure without typical spherulites, regardless of the rate of cooling. The probable role of the solvent is to facilitate mutual segregation of the microphases of both polymers in consequence of decrease in viscosity of the mixture. It has been further shown that even after briefly heating the mixture to a temperature of 220°C., before crystallization, spherulites do not form; on the contrary, spherulites originally present disappear and a structure consisting of smaller refractive formations of crystalline polymer is obtained. The formation of this structure, emerging after destruction of spherulites, might be attributed to an increase of interpenetration of both polymers and to an increase of the contact surfaces between components of the mixture.     

Some special features of open-hearth furnace bottoms

Conclusions The peculiar feature of the formation of hearths fettled with fine-grained chromemagnesite powder compared with those fettled with metallurgical magnesite powder is the formation of a more clearly expressed crystalline concretion of periclase as a result of the fine grain size composition of the powder and the presence in it of grains of chromite which help the process of hearth formation.Wear of the hearths made of chromemagnesite and magnesite powders is due mainly to one and the same factor — destruction of the crystalline concretion of periclase under the action of iron-silicate melt in the slag. The process of destruction of the hearths made from chromemagnesite powder occurs more slowly owing to the more complete formation of the concretion of crystals of periclase in these hearths, which is probably the basic cause of the higher resistance.Investigation of samples of hearth taken from the site of an accidental escape of metal through the bottom, showed that they contained crystals of iron spinel which is probably due to the local supersaturation of the hearth with iron oxides.     

聚羧酸减水剂影响抗裂性能的机理研究

通过实验,以混凝土28d的拉压比大小为评价混凝土抗裂性能的优劣，分析了合成聚羧酸减水剂的羧基、氨基、磺酸基、羟基、酯基等各官能团比例，聚醚支链的长短，减水剂分子量大小等因素对混凝土抗裂性能的影响。初步探讨了聚羧酸减水剂提高混凝土抗劈裂性能机理。     

Maternal Melatonin Deficiency Leads to Endocrine Pathologies in Children in Early Ontogenesis

The review summarizes the results of experimental and clinical studies aimed at elucidating the causes and pathophysiological mechanisms of the development of endocrine pathology in children. The modern data on the role of epigenetic influences in the early ontogenesis of unfavorable factors that violate the patterns of the formation of regulatory mechanisms during periods of critical development of fetal organs and systems and contribute to the delayed development of pathological conditions are considered. The mechanisms of the participation of melatonin in the regulation of metabolic processes and the key role of maternal melatonin in the formation of the circadian system of regulation in the fetus and in the protection of the genetic program of its morphofunctional development during pregnancy complications are presented. Melatonin, by controlling DNA methylation and histone modification, prevents changes in gene expression that are directly related to the programming of endocrine pathology in offspring. Deficiency and absence of the circadian rhythm of maternal melatonin underlies violations of the genetic program for the development of hormonal and metabolic regulatory mechanisms of the functional systems of the child, which determines the programming and implementation of endocrine pathology in early ontogenesis, contributing to its development in later life. The significance of this factor in the pathophysiological mechanisms of endocrine disorders determines a new approach to risk assessment and timely prevention of offspring diseases even at the stage of family planning.     

浅谈我国陶瓷产品出口反倾销数据动态预警系统的构建

本文首先从我国陶瓷产品贸易现状出发，阐述了建立我国陶瓷产品出口反倾销数据动态预警系统的意义，然后指出建立我国陶瓷产品出口反倾销数据动态预警系统的总体思路，并在此基础上论述建立我国陶瓷产品出口反倾销数据动态分析预警系统的主要步骤。     

Some problems of separation of mixtures

The paths of the development of research and the change of priorities in the area of separation of mixtures are tracked by the example of analysis of the works of the laboratory founded by N.M. Zhavoronkov in 1945. The studies performed encompass a wide range of basic problems of heat and mass transfer in gas absorption, distillation (including vacuum, molecular, etc.), fractional crystallization, and melting. The subjects of the works under consideration include separation of isotopes of light elements, design of mass-transfer apparatuses with high unit power, investigation of the mechanism and kinetics of separation processes, studies of separation enhancement methods, and development of hybrid energy-and resource-saving processes and equipment.     

Application of Sonic Moduli of Elasticity and Rigidity to Testing of Heavy Refractories

The application of A.S.T.M. C 215-51 T (Tentative Method of Test for Fundamental Transverse Frequency of Concrete Specimens for Calculating Young's Modulus of Elasticity) to the nondestructive testing of 1- by 1- by 7-in. laboratory fire-clay specimens and standard 9-in. fire-clay and high-alumina refractory brick is reviewed. Both room-temperature measurements and hot sonic modulus of elasticity measurements to 1700°F. are analyzed. Sonic moduli of elasticity and rigidity are compared with modulus of rupture by a theory of measurements and statistical analysis. The limits of uncertainty of the average of modulus of rupture are shown to be a function of the degree of verification whereas in the case of both sonic moduli they are not. Limits of uncertainty of the average of sonic moduli data are usually of the same order as errors calculated from the precision of measurements. In the case of modulus of rupture of well-vitrified clays, the uncertainty of the average is much greater than calculated error limits. Sonic moduli differentiate statistically between two samples of 60% alumina brick whereas modulus of rupture does not. If Poisson's ratio is assumed to be zero rather than the conventional one-sixth, ratios of sonic modulus of elasticity to rigidity are shown to approximate the theoretical ratio more closely. Effects of nonuniform density to displace normal nodes are illustrated. Hot sonic modulus of elasticity is shown to reflect changes due to crystallographic inversions, deterioration of chemical bond in unfired brick, and development of sintered bond in unfired brick.     

不脱蛋白质壳聚糖制备工艺

采用D -近似最优设计法系统地研究了NaOH质量分数、碱处理时间及碱处理温度这三个主要因素对制备壳聚糖的影响 :当碱液质量分数增加时 ,壳聚糖的脱乙酰度增加 ,但其速度却在减小 ,当碱液质量分数达到 40 %时 ,脱乙酰度出现峰值 ,约为 90 % ,而后增加碱液质量分数时 ,脱乙酰度反而下降 ;随着反应温度的升高 ,其脱乙酰度几乎线性递增 ,当温度达到 2 0 0℃附近时 ,曲线趋于平直并且脱乙酰度达到最大 ;随着反应时间的增加 ,脱乙酰度开始呈线性增加 ,当反应时间超过 5 0min后 ,脱乙酰度有下降趋势 ;在一定碱液质量分数 (4 0 % )条件下 ,脱乙酰度随着温度的增加而增加 ,因此 ,若需获得较高质量的壳聚糖 ,必须提高反应温度     

Polymerization behavior and distribution of carboxyl groups in preparation of soap-free carboxylated polystyrene latexes

Soap-free carboxylated polystyrene latexes have been prepared by copolymerizing acrylic acid (AA) in a wide range of the degree of neutralization using a slight amount of soap; and the distribution of carboxyl groups was investigated from the determination of carboxyl groups localized on the surface of particles (surface carboxyl groups). It appears that the degree of neutralization of AA or the amount of AA has a considerable effect on the rate of polymerization as well as the stability of the polymerization system. At a degree of neutralization of approximately 0.80, stable latexes are obtained at a sufficient rate of polymerization. It is also clarified that the distribution of carboxyl groups is governed substantially by the degree of neutralization of AA. At a degree of neutralization of 0.80, approximately 30% of the total carboxyl groups are localized on the surface of particles. The amount of AA or the particle diameter seems to have little effect on the distribution of carboxyl groups.     

Symmetry principles of the formation of ordered phases of crystals

General principles of the formation of low-symmetry ordered phases of crystals, such as the principle of a finite number of low-symmetry phases, the principle of phase diversity, the principle of a finite number of possible structure types of ordered phases, the principle of structural complexity, the compensation principle, and the generalized Fedorov-Groth law, are established in the framework of the Landau-Lifshitz theory of second-order phase transitions. The ranges of their applicability are determined. These principles are derived by extending the results of the structural calculations of the design of new inorganic materials with anomalous physicochemical properties.     

Numerical simulation of changes in the composition of detonation products of a free volume of a combustible mixture

Direct numerical simulation of the problem of detonation of a free volume of a gas mixture is performed to study changes in the composition of the detonation products, determine the boundaries of applicability of the model of a mixture in chemical equilibrium, and verify the sufficient condition of the applicability of the model of a chemical-equilibrium mixture proved earlier. The results on the limits of applicability of the model of a chemical-equilibrium mixture obtained earlier using an approximate method are confirmed.     

黑泥对小鼠皮肤胶原蛋白和毛发生长的影响

研究黑泥对小鼠皮肤和毛发生长的作用。将黑泥涂抹于小鼠脱毛皮肤部位,观察涂抹部位毛发生长情况,35d后取涂抹部位皮肤,测定SOD活性、胶原蛋白和丙二醛量,扫描电镜观察毛发表面结构。结果表明：黑泥能明显增加小鼠皮肤中胶原蛋白的量,提高皮肤中SOD的活性,有降低皮肤中丙二醛量的趋势,促进毛发生长,增加毛发表面光滑度。黑泥具有延缓皮肤衰老、促进毛发生长和提高毛发质量的作用。     

Release of bitumen from mature fine tailings in the presence of a polymeric dispersant

The effect of the addition of a polymeric dispersant, sodium lignosulphonate (LS), on the dispersion of mature fine tailings (MFT) was studied using zeta potential and total organic carbon measurements. Three different types of LSs were investigated to determine the importance of molecular weight and level of anionicity of LSs on the treatment of MFT. The presence of two fractions of bitumen was identified in the tested MFT sample. A small portion of bitumen was found to occur in the form of weakly held aggregates between bitumen and fine solids. This fraction was easily dispersed by small dosages of LS, resulting in bitumen liberation to the tailings surface. A much larger amount of bitumen was found to be strongly attached to the solids, and only very high dosages of LS were capable of partly liberating this fraction. The zeta potential promoted an understanding of the mechanism of adsorption of LS on the particles and liberation of bitumen from MFT. Carbon measurements facilitated determination of the adsorption density of the selected types of LS on solid particles.     

Hydrometallurgical processing of the fine dusts of copper production of OAO Kol’skaya GMK

It is established that the aqueous leaching of the dust of the conversion and sulfuric leaching of dusts of the reverberatory smelting of the Severonikel’ combine of OAO Kol’skaya GMK allows one to transfer the main amount of copper into the solution, after which, it is efficient to perform the separation of copper from the excess amount of iron via the crystallization of copper vitriol and by the liquid-phase extraction. As the sulfuric solution for leaching, we suggested the use of the gas-pipe pulps of copper production after the preliminary removal of selenium from them via cementation. The conditions of leaching and crystallization processes that provide the optimum ratio between the output and quality of copper vitriol are determined. This allows one to obtain an electrolyte suitable for copper production in the main process of electroextraction with the further dissolution of salt. The chemical and phase composition of the residues of leaching is studied, and the methods of their subsequent processing are suggested. The process flow chart of the joint processing of all fine dusts of copper production is developed.     

Realization of the strength of carbon fibres in microplastics

Based on the model of fracture of carbon-filled plastics by breakage of fibres in stretching, the strength of CF realized in a microplastic was examined as part of the strength of fibres at their critical length. Based on an analysis of the experimental and calculated data for ENFB epoxy—phenol binders, the empirical dependence of the coefficient of realization of the strength of CF in a microplastic on the modulus of elasticity of the fibres and parameter B of the scale effect of the strength of CF was established. It was shown that the parameters of the strength scale effect and modulus of elasticity of CF have the determining effect on the strength of the microplastic.Translated from Khimicheskie Volokna, No. 1, pp. 42–45, January–February, 1995.     

一种多元组合抽芯机构注射模设计

针对具有多向侧孔、内侧凹特征的相机前面板,采用注射模计算机辅助设计技术,设计一种多元组合的抽芯机构注射模具。分析了相机前面板的工艺特点及要求,介绍了模具工作原理,着重阐述了型腔布置、分型面设计、浇注系统设计、成型零部件设计、抽芯机构设计、楔紧块斜角的确定、定模板侧壁厚度的确定、脱模及复位机构设计、冷却系统设计。该模具结构合理、系统坚固,运动部分动作协调、可靠,满足塑件成型需要。     

酚醛泡沫塑料制备和性能研究

研究了酚醛泡沫制备工艺中一些参数条件对泡沫体性能的影响。研究发现：泡沫体的密度随发泡剂的用量增大而减小；表面活性剂的最适合用量为树脂质量的5％；固化剂的用量为树脂质量的4％-6％时可以达到发泡和固化同步的效果。泡沫体的吸水率与泡沫体的密度相关。力学实验表明：泡沫体的压缩强度随泡沫体的密度增大而增大。热重分析结果表明：泡沫体具有优秀的热稳定性能。     

Thermodynamic calculation of ideal and nonideal detonation

Conclusion A method has been proposed for calculating ideal and nonideal detonation, the thermodynamic basis of which is the method of characteristic function extrema, with the integral equations of conservation of the hydrodynamic model of steady-state flow of a continuous medium supplemented by the Chapman-Jouguet condition in the form of a minimum in normal detonation rate.The method has been realized in the form of a package of thermodynamic calculation programs which allow calculation of the composition and thermodynamic parameters of complex chemically reacting systems in the six basic problems of thermodynamics and in steady-state gas dynamic problems under conditions of equilibrium and specified chemical., thermal, and mechanical nonequilibrium of the products with arbitrary equations of state of the phases.Generalized results have been presented from calculations of ideal detonation of a large number of CHNO explosives and compared to experimental data. A new set of coefficients has been proposed for the BKW equation of state called the BKW-RR coefficients, which in combination with proper consideration of the phase state of the condensed carbon in the detonation products permits significant improvement in predicting the detonation rate.Results of nonideal detonation calculations have been presented, with the detonation products being under conditions of chemical, thermal, and mechanical nonequilibrium. It has been shown that the mass fraction of inert condensed phase in the detonation products not in mechanical equilibrium with the remaining products can differ significantly at the Chapman-Jouguet point from the inert content of the original mixture. Therefore, in the thermodynamic calculation of nonideal detonation one should use the equations of conservation of mass fluxes of the chemical elements in place of the equations of mass balance of chemical elements. It has been noted that in the case of nonideal detonation it is possible to use the Chapman-Jouguet condition in the form of equality of the flux velocity of the deoration product mixture as a whole relative to the front to the local speed of sound calculated with consideration of nonequilibrium conditions.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 23, No. 4, pp. 75–84, July–August, 1987.