Removal of Cadmium and Other Toxic Metals from Water: Thermophiles and New Biotechnologies

Russian Journal of General Chemistry - New experiments were carried out on testing the biomass of thermophilic and acidophilic algae Galdieria sulphuraria for removal of toxic metals cadmium (Cd),...     

Study of the optical properties of germanium films in the mid-IR spectral range

The optical properties of Si-doped germanium films have been investigated. It is shown that Ge films with 1.5 wt % Si have a minimum optical loss. The optical constants of Ge films have been measured at different substrate temperatures. The optimal conditions for producing films with minimum loss are determined.     

The effects of sample preparation methods on the variability of the electrospray ionization response for model drug compounds

A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd.     

Formation of fullerene clusters in carbon disulfide: Data on small-angle neutron scattering and molecular dynamics

Fullerene solutions in carbon disulfide are studied by small-angle neutron scattering (SANS). In addition to earlier experiments on the given system, the range of measured transmitted impulses is extended and the influence of solution preparation methods on C₆₀ cluster formation in these solutions is studied. It is shown that the formation of large C₆₀ clusters (with a size of about 10 nm) is due to nonequilibrium methods of solution preparation. For nonequilibrium dissolution, there is a 10% excess of the observed fullerene size in the solution over the calculated value. It has been established by simulation of the C₆₀/CS₂ interface by molecular dymanics methods that inclusion of how solvent molecules are organized on the C₆₀ surface leads to a decrease in the fullerene size in the solution, observed by using SANS. In this paper, the effect of excess R _g is explained by the presence of small clusters in the solution (approximately 10% of dissolved C₆₀ molecules). It is discovered that there is a time variation in the concentration of the saturated solution. The explanation of this effect using a model of formation and sedimentation of large clusters (with a size of 100 nm or more) is proposed.     

Small-angle neutron scattering data on C60 clusters in weakly polar solutions of fullerenes

Solutions of fullerence C₆₀ in carbon disulfide CS₂ have been investigated by small-angle neutron scattering. Combination of solubility, contrast, and incoherent scattering make it possible to measure and analyze the relatively small scattering cross section of this system. Along with single fullerene molecules, a small amount of large fullerene clusters (more than 100 Å in size) is found in these solutions. The formation of these clusters depends on the procedure of solution preparation. The size distribution functions of clusters are compared with the results of the phenomenological cluster model of fullerene solubility.     

Experimental investigation of microsuspension filtration in a highly-permeable porous medium

Filtration of a microsuspension of aluminosilicate particles in a highly-permeable porous medium formed by a glass-sphere filling is investigated. The particle-to-filling granule diameter ratio varied from 0.046 to 0.109 and the volumic particle concentration ratio from 0.001 to 0.02. The data on the specimen permeability dynamics and its dependence on the initial concentration of the suspension microparticles and the ratio of their diameter to that of the porous medium granules are obtained. The permeability is shown to considerably vary along the specimen. Two stages of the porous medium damage by the trapped microparticles are established. The critical parameter of the formation of an impermeable cake in the initial region of the specimen are determined.     

Finite pseudo-Boolean and topological Boolean algebras not having an independent basis of quasiidentities

Translated from Algebra i Logika, Vol. 27, No. 1, pp. 79–99, January–February, 1988.     

Nonmonotonic behavior of the concentration in the kinetics of dissolution of fullerenes

A cluster model for the dissolution of C₆₀ fullerenes in a nonpolar solvent has been proposed. This model provides the explanation of a maximum experimentally observed in the time dependence of the solution concentration during dissolution. The model is based on the kinetic equations of nucleation theory and involves a balance between the flux of fullerene molecules from the solid phase and the sedimentation of large clusters from the solution. The formation of clusters is described using the drop model. Analysis of the numerical solutions of the equations reveals four qualitatively different dissolution regimes depending on the relation between the model parameters.     

关于单位园周上阶梯函数的性质

Ｔ．Ｓｈｅｉｌ－Ｓｍａｌｌ［１］讨论了阶梯函数的Ｆｏｕｒｉｅｒ级数。本文对［１］中所涉及到一些阶梯函数的性质进行了详细讨论，并给出了详细证明。