Using of the Agglomeration-in-liquid for the Technology of the Fine Materials

The content of the fine and ultrafine particles in the raw material results in difficulty of the separation, the loss of the valuable components and ecological contamination. Secondary using of the fine particles is impossible without their granulation. This problem has been solved by the agglomeration-in-liquid method.An agglomeration-in-liquid method is a process to produce agglomerates in a liquid phase from solid particles suspended in the liquid. The surface of solid particles and the binding liquid must be of identical polarity, but the continuous phase must be of the opposite polarity. The water solutions of the surfactant are the binding liquids or the organic liquids.     

The computation of the representation matrices of the generators of the unitary group

A method is presented for the efficient computation of the representation matrices of the unitary group, U(n) in the Gelfand—Tsetlin basis (corresponding to the usual spin-symmetry adapted basis for an N electron CI). The present scheme is conceptually and computationally attractive in that it is formulated directly in terms of Weyl tableaux and also that it permits simultaneous basis vector generation and matrix element evaluation. In addition the basis vectors are ordered so that subsequent restriction to the three dimensional rotation group is facilitated. An illustrative example is also presented.Taken in part from a thesis submitted to the University of London in partial fulfilment of the requirements for the degree of PhD.     

FTIR study of the mode of binding of the reactants on the Pd nanoparticle surface during the catalysis of the Suzuki reaction

In the Suzuki reaction between phenylboronic acid and iodobenzene catalyzed by palladium nanoparticles, our previous studies suggested that the phenylboronic acid adsorbs on the nanoparticle surface and then interacts with the iodobenzene that is present in solution. In the present study, FTIR is used to examine the change in the vibrational frequencies of phenylboronic acid in films with and without the addition of palladium nanoparticles. The large change in the B-O stretching frequency of phenylboronic acid from 1348 to 1376 cm(-1) in the presence of sodium acetate and palladium nanoparticles strongly suggests that the mode of binding of phenylboronic acid to the Pd nanoparticle surface involves a B-O-Pd type of bonding. Shifts in the B-C stretching mode and the out-of-plane phenyl C-C ring deformation bands associated with phenylboronic acid provide additional confirmations of the binding process. It is also shown that the phenylboronic acid needs to be in the deprotonated form in the presence of sodium acetate (phenylboronate anion) to bind to the palladium nanoparticle surface. No changes in the characteristic bands of iodobenzene were observed in films made in the presence of the palladium nanoparticles. The FTIR studies provide proof of the mode of binding that occurs in the nanoparticle surface for the first time and also confirms the mechanism of the Suzuki reaction that we proposed previously.     

光亮剂对银电沉积行为的影响

用电势阶跃法和旋转圆盘电极法 (RDE)以及SEM和XRD测试手段 ,初步研究了光亮剂对氰化体系中银电沉积行为的影响 .研究表明 ,光亮剂的加入并未导致银电沉积成核机理的改变 ,但显著增强了镀液的微观平整效应 ,并且所得镀层的表观光滑程度明显改善 .XRD测试亦同时表明光亮剂的加入并未改变镀层的择优取向     

Effect of the nature of the solvent and the temperature on the frequency and intensity of the stretching vibration of the Ge-H bond in the IR spectra of 1-hydrogermatranes

Conclusions The Ge-H stretching vibration in the IR spectra of 1-hydrogermatranes varies under the influence of the solvent and the temperature as a result of the presence of the transannular Ge N bond. The change in the length of this bond with variation in the polarity of the solvent and the temperature of the solutions is smaller in germatranes than for the Si N bond in the isostructural silatranes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1758–1761, August, 1985.     

Importance of the catalytic effect of the substrate in the functionality of lubricant additives: the case of molybdenum dithiocarbamates

Molybdenum dithiocarbamates (MoDTCs) are lubricant additives very efficient in reducing the friction of steel, and they are used in a number of industrial applications. The functionality of these additives is ruled by the chemical interactions occurring at the buried sliding interface, which are of key importance for the improvement of the lubrication performance. Yet, these tribochemical processes are very difficult to monitor in real time. Ab initio molecular dynamics simulations are the ideal tool to shed light on such a complicated reactivity. In this work, we perform ab initio simulations, both in static and tribological conditions, to understand the effect of surface oxidation on the tribochemical reactivity of MoDTC, and we find that when the surfaces are covered by oxygen, the first dissociative steps of the additives are significantly hindered. Our preliminary tribological tests on oxidized steel discs support these results. Bare metallic surfaces are necessary for a stable adsorption of the additives, their quick decomposition, and the formation of a durable MoS₂ tribolayer. This work demonstrates the importance of the catalytic role of the substrate and confirms the full capability of the computational protocol in the pursuit of materials and compounds more efficient in reducing friction.     

Dependence of the composition of the lipids of the seeds ofPlectranthus glaucocalyx on the conditions of growth

A change in the geographical growth zone and in the density of the soil has a substantial influence on the amount of lipids in the seeds ofPlectranthus glaucocalyx Maxim. and their degree of unsaturation, and also on the structure of the triacylglycerols.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 30–35, January–February, 1984.     

Effects of the composition of the reaction mixture and the nature of the template on the structure of mesoporous aluminosilicates formed in the presence of lecithin

It has been established that supramolecular structures of lecithin can act as templates in the synthesis of mesoporous aluminosilicates. Mesoporous substances, with pore dimensions up to 100 Å and biporous materials can be obtained when various combinations of lecithin with cetyltrimethylammonium bromide or octadecylamine are used as template agents in the aluminosilicate system.     

The application of the OTA of kerogen to the evaluation of the rockmass heating

Oxyreactive thermal analysis (OTA) carried out in the conditions of full access of oxygen to each reacting particle of the sample investigated is a suitable method for the determination of important properties of the organic matter dispersed in the rocks. Its results may be easily evaluated to the form of values to be used in a clear diversification and classification system of organic matter/kerogen, as well as to the evaluation of its transformation process in a rockmass. The OTA also enables the distinguishing of the transformation stages and the investigation of the results of the gaseous products liberation from organic matter and kerogen. The OTA method may be applied as a complementary one for the Rock Eval analysis and be used for the organic geochemical and bituminological studies for geological bitumen prospecting.This revised version was published online in November 2005 with corrections to the Cover Date.     

Elements of the topology of the region of the existence of the metastable states of a two-component vapor

Entire regions of the metastable states for binary and single-component systems were constructed. It was established that the regions include temperature intervals from absolute zero to critical temperatures, and from vapor—condensate equilibrium to the conditions of spinodal decomposition of supersaturated vapor in the system. Algorithms for determining the regions of metastable states are presented. The data obtained on their basis are noted to coincide qualitatively with known results. Correlations found earlier are employed to calculate the critical pressures and temperatures for the binary systems in the study.     

Investigation of the lability of the conformations of some alkaloids of the quinolizidine series

Summary The IR and NMR spectra of lupinine, epilupinine, and a series of other alkaloids of the quinolizidine series have been studied.It has been shown that the inhibition of the inversion processes in the molecules of the alkaloids in the solid phase is revealed in a change in the nature of the absorption in the 500–1200 cm^2–1 region.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 49–54, January, 1971.     

Study of the influence of the graphite powder particle size on the structure of the Sonogel-Carbon materials

In this paper, the influence of carbon particles size on structure and on electrochemical and physical properties of the Sonogel-Carbon electrodes, with respect to Sonogel materials without graphite, have been studied. The materials have been characterized electrochemical and structurally; several Sonogel-Carbon materials were synthesized using different types of graphite powder as massive modifiers, adding in some cases other modifiers, such as octadecyl (C18) and polyethyleneglycol (PEG). Differential pulse voltammetry and cyclic voltammetry were the voltammetric techniques employed to evaluate the electrochemical behaviour; Scanning Electron Microscopy, Energy Dispersive Spectroscopy and Infrared Spectroscopy were the techniques employed to realize the superficial/structural characterization of the materials. The results obtained in both studies were very useful to explain the structure of the Sonogel-Carbon materials. Furthermore, they allowed to conclude that electrodes based on RW-B and UF graphites show very similar electrochemical behaviours and internal structures.     

A study of the lignin of the cotton plant of the subspeciesmexicanium

p-Hydroxybenzoic, vanillic, ferulic, and syringic acids, and also p-hydroxybenzalde-hyde and vanillin, have been found in an ethanol-benzene extract of the stems of cotton plants of the subspeciesmexicanium. The dioxane lignin (DLA) has been isolated by Pepper's method, the semiempirical formula of its phenylpropane structural unit and its molecular-mass distribution have been established, and its UV, IR, and PMR spectra have been recorded. The DLA has a comparatively low molecular mass and a lower degree of polydispersity than the dioxane lignin of the cotton plant of variety Tashkent-1, while the amounts of functional groups in them coincide, with the exception of a lower amount of carboxy groups in the DLA.     

An improvement of the resolution of the identity approximation for the formation of the Coulomb matrix

A straightforward modification of the resolution of the identity (RI) approximation to the Coulomb interaction is described. In the limit of basis sets that are dominated by high angular momentum functions the observed speedups in realistic test systems reach a factor of 2 compared to the standard RI algorithm, and a factor of up to 300 compared to the standard algorithm to form the Coulomb matrix. More moderate savings on the order of 0-20% are obtained for the more commonly used smaller basis sets. A series of test calculations is reported to illustrate the efficiency of the algorithm.     

On the mechanism of the laccase-mediator system in the oxidation of lignin

In an effort to elucidate the role of phenolic and non-phenolic lignin subunits in a laccase mediator (LM) system, vanillyl alcohol was oxidized with laccase in the presence and absence of the mediator 1-hydroxybenzotriazol (HBT). Furthermore, the role of phenolic, aliphatic hydroxyl, and carboxylic acid moieties in lignin degradation was elucidated by selectively blocking them. The modified samples were then subjected to laccase and laccase-HBT treatments. On the basis of this data it was possible to establish the role of this mediator. HBT mediates the oxidation of lignin by inducing side-chain oxidation and oxygen-addition products rather than oxidative coupling reactions.     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shifts of the ring protons on the pH of the medium for a number of 4-hydroxyquinoline derivatives was studied by means of PMR spectroscopy. The dipolar and uncharged hydroxy forms exist in equilibrium in aqueous solutions. The effect of intramolecular hydrogen bonding on the character of the dependence of the chemical shift on the pH of the medium in the case of 3-piperidinomethyl-4-hydroxyisoquinoline was investigated. The possibility of the separate protonation of the ring nitrogen and the side-chain nitrogen in 3-piperidinomethyl-4-hydroxyisoquinoline was established. The distribution of the -electron density in 4-hydroxyisoquinoline is in good agreement with its chemical behavior.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1549, November, 1971     

Investigation of the mechanism of the polarographic reduction of the sydnoneimmonium cation

The polarographic reduction of the sydnoneimmonium cation (I) was investigated in the case of 3--phenylisopropylsydnoneimine hydrochloride (sydnophen). The effect of the pH, alcohol concentration, ionic strength, and surface-active substances was studied, and the electrolysis was carried out at a controllable potential under various conditions. The cyclic voltampefograms were recorded. A mechanism for the reduction of I is proposed. Cleavage of the ring of I in the near-electrode space is observed in unbuffered media. The first direct proof of the existence of the unstable sydnoneimine base was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1042–1048, August, 1975.     

Effect of the shape of human erythrocytes on the evaluation of the passive electrical properties of the cell membrane

The possible influence of the cell shape on the derivation of the passive electrical parameters of a biological cell membrane is discussed in light of two different models which describe the cell as a shelled ellipsoidal particle and as a biconcave disk obtained by the revolution of the Cassini oval, respectively. Whereas within the first model, the Laplace equation can be solved analytically, in the second one a numerical algorithm based on the boundary element method has been employed. We have compared the results obtained by these two different models in the case of normal human erythrocyte cell membrane, using radiowave dielectric spectroscopy measurements. Our findings show that, although in principle the cell shape might deeply affect the evaluation of the passive electrical parameters of the cell membrane, in the case of the erythrocyte shape modelled by the Cassini curve, only small deviations are evidenced in comparison to the values derived, as usually done in the dielectric spectroscopy of biological cell suspensions, from an ellipsoidal model analysis. This result gives further support to the reliability of the data reported in the literature based on an ellipsoidal shape erythrocyte model.     

HPLC-methods in the clinical-chemical laboratory of the department of dermatology of the University of Bonn

Summary High performance liquid chromatography (HPLC) is increasingly used in clinical chemistry for the detection of a great variety of components. This paper describes examples of HPLC analyses of drugs, metabolites and endogenous components in blood, urine and tissue homogenates.     

Correlation Analysis of the Runoff of the Rivers and the Seisms in China

In recent hundred years the annual discharge variations of the Changjiang River (represented by the Yichang station) and the Huanghe River (represented by Shanxian and Tangnaihe, respectively) have closely related to the geographical distribution of the earthquakes coming about in China in the same year, Both the occurrence of the destructive seism or seismic swarm in the river basins and the disappearance of the shocks in the east and south of the basins are the conditions that the Changjiang and Huanghe Rivers are the high flow while that the strong earthquake of magnitude 7 or more occurred in North China is the condition for the Changjiang low flow year and that of 6 or more in the Qilian Mountains area is for the Huanghe River. In the latter part of this paper, a 2-year sample is given to explain that the conditions of the 2 rivers being high flow years are that the north-south seismic belt is active and in the meanwhile no seism occurred in South China, and those of the low flow year are that the