Statistical Analysis of Differential Potentiometric Precipitation Titration Data for a Mixture of Three Heterovalent Ions Using Linear Characteristics

A computer-based method is proposed for data processing in the successive potentiometric precipitation titration of a three-component mixture of differently charged ions. It is based on a piecewise transformation of the titration curve into linear regression characteristics, the parameters of which determine the successive equivalence points and the solubility products of the precipitates formed in the course of titration to the accuracy of least-squares estimates. To implement the calculation algorithm, a DIFTITR2 program written in Turbo Pascal was developed. The method was tested on the titration of an artificial solution containing a mixture of Cd(II), Hg(II), and Te(IV) with diethyldithiocarbamate, using a chalcogenide Cd-selective or a glassy-carbon indicator electrode, and was used for the analysis of the main components in a semiconductor material, namely, a solid solution of mercury and cadmium tellurides. For concentrations of test ions in the model solution from 7.5 × 10^–3 to 3 × 10^–4 M, the RSD value varies from 0.01 to 0.3; the determination error does not exceed 6%. The RSD value for the semiconductor alloy lies in the range of from 0.002 to 0.01.     

Tricomi problem for <Emphasis Type="Italic">q</Emphasis>-difference analog of anticipatory-retarding equation of mixed type

We investigate a boundary-value problem for mixed-type equation with the Lavrent’ev–Bitsadze operator in the main term and q-difference deviations of the argument in the lowest terms. We construct a general solution to the equation and prove a uniqueness theorem without restrictions on the deviation value. Then we show that the problem is uniquely solvable and find integral representations of the solution in the elliptic and hyperbolic domains.     

A study of Galerkin method for the heat convection equations

This article investigates the Galerkin method for an initial boundary value problem for heat convection equations. The new error estimates for the approximate solutions and their derivatives in strong norm are obtained.     

Investigation of clustering in light nuclei by means of relativistic-multifragmentation processes

New results concerning the topology of the fragmentation of relativistic nuclei ⁷Li and ¹⁰B are presented. A program is proposed for studying the cluster structure of stable and radioactive nuclei. The use of emulsions in the investigation of nuclear clustering in the fragmentation of light nuclei at energies are in excess of 1 GeV per nucleon is discussed.     

Charge topology of the coherent dissociation of relativistic <Superscript>11</Superscript>C and <Superscript>12</Superscript>N nuclei

The charge topology of coherent-dissociation events is presented for ¹¹С and ¹²N nuclei of energy 1.2 GeV per nucleon bombarding nuclear track emulsions. This topology is compared with respective data for ⁷Be, ^8,10B, ^9,10C, and ¹⁴N nuclei.     

Electromagnetic dissociation of relativistic 8B nuclei in nuclear track emulsion

Experimental data on fragmentation channels in peripheral interactions of ⁸B nuclei in nuclear track emulsions are presented. A detailed analysis made it possible to justify selections of events of the electromagnetic-dissociation process ⁸B → ⁷Be + p and to estimate its cross section. Events of ¹⁰C peripheral dissociation that were observed in the same exposure are described.     

Peripheral fragmentation of 8B nuclei in nuclear emulsion at an energy of 1.2 GeV per nucleon

The results obtained by studying the charge topology of fragments produced in the peripheral dissociation of relativistic ⁸B nuclei in emulsion are presented. Fifty-five events of the peripheral dissociation of a ⁸B nucleus in events where there was no production of target-nucleus fragments and mesons (“white stars”) were selected. A leading contribution of the ⁸B → ⁷Be + p mode, which has the lowest energy threshold, was revealed on the basis of these events. Information about the branching ratios for dissociation modes characterized by a higher multiplicity was obtained. The dissociation of the ⁷Be core in ⁸B bears resemblance to the dissociation of a free ⁷Be nucleus. The transverse-momentum distributions of fragments originating from the ⁸B → ⁷Be + p dissociation mode were obtained. For these distributions, a small mean value of 〈P*_T〉 = 52 ± 5 MeV/c in the c.m. frame suggests a low binding energy of the outer proton in the ⁸B nucleus. An indication of a strong azimuthal correlation of the fragments ⁷Be and p was found.