Physical aspects of the model of propagation of centimeter and millimeter radio waves along inclined paths in the earth’s atmosphere

We present the physical aspects of constructing a computer model of propagation of centimeter and millimeter radio waves along inclined paths in the earth’s atmosphere, which allows us to calculate the integral attenuation in the frequency spectrum from 3 to 100 GHz, the time of group delay of the signal, refraction of radio waves, and the brightness temperature of the atmosphere for certain regions on the basis of standard atmospheric models and optimal statistical extrapolation of surface meteorological elements. The results of this paper were presented in part at the XVIIIth All-Russia Conference on Propagation of Radio Waves (St. Petersburg, September 17–19, 1996 [1] Radiophysical Research institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 12, pp. 1463–1478, December, 1997.     

Comparison of thermal characteristics of degenerated and inflamed human collagen structures with differential scanning calorimetry

Collagen is the primary structural protein of the human body and the main component of connective tissue. In the form of elongated fibrils, collagen is mostly found in fibrous tissues such as tendon, ligament, and skin. We have already demonstrated that pathologic changes of human collagen structures could be monitored by differential scanning calorimetry (DSC), besides the classical histological methods. The aim of the study was to find whether there is a consistent increase or decrease of the thermal parameters, if we compare the changes of calorimetric enthalpy and denaturation temperature of (1) group: degenerative with (2) group: inflamed collagen structures. The degenerative samples were collected from ruptured Quadriceps, Achilles, patellar and anterior cruciate ligament, and degenerated joint capsule of the shoulder. The inflamed tissue samples were collected from palmar aponeurosis in Dupuytren disease, transverse carpal ligament in carpal tunnel syndrome (CTS), and transverse ligament of the first dorsal compartment in De Quervain disease. The thermal denaturation of human samples was monitored by a SETARAM Micro DSC-II calorimeter. All the experiments were performed between 0 and 100 °C. The heating rate was 0.3 K min^?1. DSC scans clearly demonstrated significant differences between the two groups, proving that the thermal stability of the degenerative and inflamed pathologic collagens is significantly different. In cases of degenerative samples, the enthalpy decreased, while the melting temperature showed an increase. On the contrary, inflamed samples demonstrated a significant increase in the enthalpy and the melting temperature decreased. Our results indicate that DSC may be a clinically relevant method in the diagnosis of different collagen diseases.     

Nature of the convective state of crystals in “ultrahigh pressure + shear” conditions

The proposition is supported that the influence of ultrahigh pressure leads to the creation of a convective crystal state in which the entire ensemble of atoms is divided into strongly and weakly excited atoms. The first of these are found in a delocalized state, achieving the convective mass transfer regime, and the second are responsible for crystal structure.Translated from Izvestiya Vysshikh Uchebnikh Zavedenii, Fizika, No. 6, pp. 34–40, June, 1986.     

Growth conditions,structure, and composition of Sm123 crystals

Conditions have been found for reproducible growth of Sm123 crystals by spontaneous crystallization from a nonstoichiometric melt in an Sm-Ba-Cu-O system using an alundum crucible. Crystals with dimensions 3×3×0.1 mm (average) and 6×3×0.5–1.0 mm (maximal) have been obtained. The chemical composition of the crystals has been determined, and it was found to be uniform (chemical and electron-probe X-ray analyses). X-ray diffraction analysis was used for structure and composition refinement for four crystals. Tetragonal crystals, space group P4/mmm, cell parameters a = 3.8921–3.8937 Å, c = 11.683–11.695 Å. Under conditions of synthesis, barium is not replaced by samarium; the absence of superconductivity is explained by the presence of an aluminum admixture at Cu(1) positions.     

Prompt leptons in cosmic rays

Summary Energy spectra and zenith-angle distributions of cosmic-ray muons, neutrinos and antineutrinos of prompt generation for energy interval (1÷10⁶) TeV are calculated. For calculations of differential cross-sections of D^±, D⁰, ⁰ and Λ_c production inNN and πN interactions the recombination quark-parton model (RQPM) is used. Accounting of nuclear effects is done by using the additive quark model and the optical model of nucleus. Detailed comparison of results obtained in RQPM with corresponding predictions of quark-gluon string model (MQGS) is carried out. Dynamics of semi-leptonic D- and Λ_c and energy losses of muons in the atmosphere are taken into account. Calculations of hadronic cascades in the atmosphere are done with accounting of growth with energy of total inelastic hadron-nucleus cross-sections, steepening of primary cosmic-ray spectrum and processes of pion regeneration. The comparison of our calculations with experimental data and with calculations of other authors is given.     

Mechanochemical synthesis and crystal structure of acetylacetonate complexes with the triangular Mo3Q7 4+ core (Q = S or Se)

Mechanochemical reactions of inorganic polymers ¹ _∞[Mo₃Q₇Br₄] (Q = S or Se) with sodium acetylacetonate hydrate lead to excision of the Mo₃Q₇ ⁴⁺ cluster core giving rise to the cationic complexes [Mo₃Q₇(acac)₃]⁺. Extraction of the reaction mixture with acetone followed by recrystallization from a benzene-hexane mixture afforded the {[Mo₃S₇(CH₃COCHCOCH₃)₃]Br}·2C₆H₆ (1) and {[Mo₃Se₇(CH₃COCHCOCH₃)₃]Br}· · 2C₆H₆ (2) complexes. The structures of complexes 1 and 2 were studied by IR and ¹H NMR spectroscopy and X-ray diffraction. Compound 1 was characterized by electrospray mass spectrometry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1895–1898, November, 2006.     

Molecular Structure of Diphenylphosphine As Determined by Gas-Phase Electron Diffraction and Quantum-Chemical Calculations

Gas-phase electron diffraction was used to show the title molecule has an asymmetric structure with torsion angles around P-C bonds of 65° and 154(7)°. The principal geometric parameters are as follows: interatomic distances, Å: P-C 1.829 and 1.833(4), C-Cav 1.401(1); bond angles, deg: CPC 101.0(20), PCC 120.4 and 119.4(16). Quantum-chemical calculations of chlorodiphenylphosphine were performed.