Application of Blanc’s law at arbitrary electric field to gas density ratios

Application of Blancs law for drift velocities of electrons and ions in gas mixtures at arbitrary reduced electric field strengths E/n₀ was studied theoretically and by numerical examples. Corrections for Blancs law that include effects of inelastic collisions were derived. In addition we have derived the common mean energy procedure that was proposed by Chiflikyan in a general case both for ions and electrons. Both corrected common E/n₀ and common mean energy procedures provide excellent results even for electrons at moderate E/n₀ where application of Blancs law was regarded as impossible. In mixtures of two gases that have negative differential conductivity (NDC) even when neither of the two pure gases show NDC the Blancs law procedure was able to give excellent predictions.     

Guiding center theory for ion holes in magnetized plasmas

A drift-kinetic theory for ion phase-space vortices in magnetized plasmas is developed, taking into account the effects of the ion polarization and anisotropic heating by ion beams. It provides a theoretical explanation for the bipolar electrostatic structures in the auroral zone of the Earth's magnetosphere and their spatial and temporal scales, as observed by S3-3, Viking, FREJA, Polar, and FAST spacecrafts. Several types of quasi-three-dimensional ion holes are obtained analytically, in the form of either cylinders or ellipsoids. Although topologically different, they produce similar signals on the spacecraft and cannot be distinguished on the basis of the existing satellite data.     

Radiochemical quality control of99mTc-labelled radiopharmaceuticals

Two methods for the determination of radiochemical purity of preparations labeled with^99mTc are described. Paper chromatography was used for separation of reduced^99mTc and free pertechnetate from the labeled radiopharmaceutical. Whatman 3MM paper was used first with a acetone and then with 1N NaCl, as the mobile phase. Instant thin layer chromatography was performed for comparison. The electrophoretic method was also applied, using 0.05 M Na-acetate and 0.017 M NaCl. Biodistribution of^99mTc-DMSA in the organs of experimental animals was followed in order to verify chemical control methods.     

Quality control and statistical analysis of biodistribution of commercial99mTc-IDA derivatives

The results obtained for radiochemical purity of ITLC (SA) and (SG) using different solvent systems and low voltage electrophoresis are presented in the paper. Radiochemical purities obtained for^99mTc-dimethyl IDA (^99mTc-HIDA) and^99mTc-diethyl IDA (^99mTc-EHIDA) are 98.1±0.6% and 98.7±0.5%, respectively. Variable^99mTc hydrolyzate contents, depending on the ionic strength of the eluents and on the time interval between labelling and analysis, have been obtained by Sephadex chromatography. The eluent containing Sn-EHIDA inhibits dissociation of^99mTc-EHIDA due to dilution of the preparation during elution of the column and yielding only a small percent of Sephadex bound fraction, as compared to other investigated eluents. The range of normal^99mTc-IDA biodistribution values in the organs of experimental animals and statistical significance of the difference between these two preparations have also been determined. The results obtained for^99mTc-HIDA and^99mTc-EHIDA in the liver are 33.9±5% and 25.7±4.7%, respectively p<0.01.     

Determination of radiochemical purity of chlormerodrin-203 by electrophoretic method

An electrophoretic method to control the radiochemical purity of chlormerodrin-203 is described. Optimum conditions for the separation of inorganic and organically bound mercury-203 were determined by investigating its mobility in the concentration range of 1·10⁻⁵–1·10⁻² M NaCl. Maximum separation, of²⁰³Hg and hydroxychlormerodrin was achieved at 0.05M NaCl, at the potential gradient of 8V/cm for 2 hrs.     

Mass spectrometric study of some 4-pyrimidine carboxylic acids

Mass spectrometry has been applied in order to study the main fragmentation routes of some 4-pyrimidene carboxylic acids. Differences in fragmentation were caused by the nature of the substituent in position 2 of the pyrimidine ring, while the methyl group in position 1, 3 or 6 did not influence the fragmentation route.     

Thermal behavior of gamma-irradiated urea–formaldehyde composites based on the differently activated montmorillonite K10

Journal of Thermal Analysis and Calorimetry - This work investigated the thermal characteristics of irradiated composite materials formulated on the urea–formaldehyde resin (UF) and...     

Analysis and numerical approximation of a parabolic-hyperbolic transmission problem

In this paper we investigate a mixed parabolic-hyperbolic initial boundary value problem in two disconnected intervals with Robin-Dirichlet conjugation conditions. A finite difference scheme approximating this problem is proposed and analyzed. An estimate of the convergence rate is obtained.     

Optimal strong Mal’cev conditions for congruence meet-semidistributivity in locally finite varieties

Locally finite, congruence meet-semidistributive varieties have been characterized by numerous Mal’cev conditions and, recently, by two strong Mal’cev conditions. We provide three new strong Mal’cev characterizations and a new Mal’cev characterization each of which improves the known ones in some way.