Syntheses, spectroscopic characterization and X-ray structural studies of lanthanide complexes with adamantyl substituted 4-acylpyrazol-5-one

Synthesis and spectroscopic characterization of new lanthanide complexes [Ln(Q_AD)₃(EtOH)(H₂O)], (Ln = Tb, Eu; HQ_AD = 1-phenyl-3-methyl-4-adamantylcarbonyl-pyrazol-5-one), [H₃O][Tb(Q_AD)₄], [Ln(Q_AD)₃(N-N)] (Ln = Tb, Eu; N-N = 1,10-phenanthroline (Phen), 2,2′-bipyridyl (Bipy), 4,4′-dimethyl-2,2′-bipyridyl (4,4′-Me₂Bipy)) are reported. The crystal structures of the proligand HQ_AD and of complexes [H₃O][Tb(Q_AD)₄] and [Tb(Q_AD)₃(4,4′-Me₂Bipy)] have been determined. In both complexes the lanthanide ions are in a square antiprismatic environment, the H₃O⁺ cation in the former acid complex being stabilized by H-bonding. Luminescence studies have been performed on selected derivatives.     

Electrophoretic mobility of DNA in gels. I. New biased reptation theory including fluctuations

In weak electric fields, the motion of DNA molecules undergoing gel electrophoresis may be described by biased reptation. We argue that the degree of molecular orientation induced by the field is determined by a competition between longitudinal fluctuations and drift of the molecule along the tube. A self-consistent calculation shows that the end-to-end vector of long molecules varies with the square root of the field strength, and not linearly as previously supposed. This leads to a number of new predictions about the field dependence of the molecular mobility and the size limit of resolution. We present the results of computer simulations that support the predictions of the theory of biased reptation including fluctuations. Finally, we discuss the correspondence with experimental data and the implications of our findings for the optimization of DNA electrophoresis. © 1994 John Wiley & Sons, Inc.     

One-dimensional model of a helicon discharge

A simplified model describing the steady state of a helicon discharge in a low-pressure plasma is considered. The electron Langmuir frequency of the plasma produced by the discharge is shown to be much higher than the electron gyrofrequency. It is found that the gas medium is ionized and the electrons are heated primarily by the extraordinary mode. The calculated electron density depends nonmonotonically on the magnetic field, in agreement with the results of numerous experiments.     

Functional capacity of the kidneys in whole-body irradiated rats protected with gammaphos and merkamine

In experiments with Wistar rats it was shown that gammaphos promotes the recovery of the kidneys' filtration function at early times after 7.4 Gy gamma-irradiation and inhibits it after 210 days. Merkamine induces haemodynamic and functional disorders in the exposed rat kidneys within the first 30 days after irradiation.     

Reaction of the cerebral cortical neurons to complete ischemia]

Changes of morphological and neurophysiological characteristics of pyramidal neurons in response to complete ischemia have been studied by means of vital microscopy of cat and rabbit cortex neurons in addition to some other cytological methods. These responses were found to be complex involving phasic changes in the neuron size, membrane potential and redox potential. Neurons of particular types responded to normo- and hypothermic ischemia differently. Pyramidal neurons retained their vital ability for the whole prolonged period of the complete ischemia (up to 40--60 min).     

Organizational and methodological approaches to using digital X-ray fluorography in the diagnosis of lung diseases in practical public health care of the Russian Federation

On the basis of a great body of information, the authors propose the most reasonable and effective organizational and methodological approaches to further actively introducing digital lung fluography into Russia's practical public health care. The paper discusses a diversity of topical problems associated with the practical use of digital X-ray fluorography (DXF), such as the assessment of its use depending on the level (municipal or regional) of public health care, methodological issues of its performance, current relationships of DXF and film fluorography; a place of DXF in the screening and routine clinical diagnosis of lung diseases. Great emphasis is laid on the role of DXF in the diagnosis of tuberculosis and cancer of the lung. The place and role of Russian manufacturers of digital lung fluorographs in the further development of SXF in practical public health care of Russia are also touched upon. The authors emphasize that replacement of film fluorography by digital one will present difficulties if regional and municipal health administrators do not take an active part in this matter.