Prognostication criterion of potential and practical use of analytical reagents in titrimetria of individual substances

Various possible criterion in titrimetric methods have been discussed in this paper and more informative, visual and universal criterion-the degree of proceeding of individual reaction at the equivalence point have been chosen. The equation for the degree of proceeding of individual analytical reaction suited for any chemical reactions under real conditions with an allowance made for both component and titrant concentration have been deduced. This criterion allows us to make a prognosis of any parametres of a titrimetric procedure of an individual substance determination and the procedure as a whole, not having carried out the experiment.     

The determination of environmental and industrial exposure to heavy metals based on the quantitative isolation of metallothionein from human fluids, with application of covalent affinity chromatography with thiol-disulphide interchange gel as a solid-phase extraction support

The aim of this study was to present a new analytical method for the quantitative determination of metallothionein (MT) proteins in human body fluids and tissues, in order to determine the level of environmental and industrial exposure to heavy metals. For MT isolation, covalent affinity chromatography with thiol-disulphide inter-change (CAC-TDI) was applied. Fundamentals of indirect determination of the contents of metallothionein proteins were worked out through estimation of the quantities of metals bound with metallothionein protein and adsorbed on covalent affinity chromatography gel as on solid-phase extraction support during separating process. The (CAC-TDI) gel, specially prepared, was used as a solid phase extraction support (SPE) for preconcentration of Hg-thionein (Hg-Th), Cd-thionein (Cd-Th), Zn-thionein (Zn-Th) and Cu-thionein (Cu-Th) proteins and Hg, Cd, Zn and Cu bonded with MTs from water, human fluids such as: urine, human plasma, breast milk and tissues homogenates.     

Effect of ‘Transannular Transmission’ in Dibenzo-18-Crown-6

The effect of the nature of the substituent in the monosubstituted derivatives of dibenzo-18-crown-6 on the reactivity and direction of the electrophilic substitution reaction of the unsubstituted benzene ring has been determined. This transfer is carried out via the macrocycle and therefore is called transannular transmission. The possible mechanism of this transmission is discussed.     

AM1 study of photoelectron spectra.

The -orbital structure of the monomeric form of the 2,2,4,6-tetrachloro-2,2-dihydro-1,5,2-diazaphosphorinine has been studied by photoelectron spectroscopy and using quantum-chemical calculations by the semiempirical AM1 method. It has been concluded that the electronic and energy characteristics of four higher -MOs (frontier and three next orbitals) of this compound may be interpreted in terms of semipolar bonds formed by three atoms (C, P, and N). For describing two low-lying -MOs of the ⁴,⁵-phosphorine studied, it is necessary to take into account the --interaction.For Part 8, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 827–831, April, 1996.     

Hydraulic conductivity of rock fractures

The flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of fluid mechanics. The derivation of the cubic law is given as the solution to the Navier-Stokes equations for flow between smooth, parallel plates - the only fracture geometry that is amenable to exact treatment. The various geometric and kinematic conditions that are necessary in order for the Navier-Stokes equations to be replaced by the more tractable lubrication or Hele-Shaw equations are studied and quantified. In general, this requires a sufficiently low flow rate, and some restrictions on the spatial rate of change of the aperture profile. Various analytical and numerical results are reviewed pertaining to the problem of relating the effective hydraulic aperture to the statistics of the aperture distribution. These studies all lead to the conclusion that the effective hydraulic aperture is less than the mean aperture, by a factor that depends on the ratio of the mean value of the aperture to its standard deviation. The tortuosity effect caused by regions where the rock walls are in contact with each other is studied using the Hele-Shaw equations, leading to a simple correction factor that depends on the area fraction occupied by the contact regions. Finally, the predicted hydraulic apertures are compared to measured values for eight data sets from the literature for which aperture and conductivity data were available on the same fracture. It is found that reasonably accurate predictions of hydraulic conductivity can be made based solely on the first two moments of the aperture distribution function, and the proportion of contact area.