NEW SEMISYNTHETIC CEPHALOSPORINS WITH ANTIBACTERIAL,ANTIVIRAL AND ANTIFUNGAL ACTIVITY

Abstract

The synthesis of new derivatives of thiazolidine 2-alkylidene-4-on-5-acetamidocephalosporanic acids or thiazolidine 2-arylidenazino-4-on-5-acetamidocephalosporanic acids and their salts of general formula (I) has been achieved.     

Comparison of the efficacy of sulfurization agents in decreasing the sheet resistance of polyamide and polyethylene with copper sulfide layers and influence of their compositions

The process of obtaining semiconductive and electrical conductive layers of copper sulfides by the sorption — diffusion method on polymers (polyamide 6 and low density polyethylene) using solutions of potassium pentathionate, K₂S₅O₆, and higher polythionic acids, H₂S _n O₆ (n = 21, 33), was investigated. The layers were characterized for compositional and electrical properties by X-ray diffraction (XRD) analysis and sheet resistance measurements. The thickness of copper sulfides layers on polyamide and polyethylene increased with increasing time of polymer sulfurization and varied from 10 to 43 μm. The variations of the sheet resistance of copper sulfides layers formed on the surface of polymers on sulfurization agent used, the conditions of sulfurization, chemical and phase composition of the obtained layers were established. Sheet resistance of copper sulfides layers decreases with increasing time of the duration of sulfurization and the number of sulfur atoms in the polythionate anion. The sheet resistance values for copper sulfide layers formed on the polyamide surface are much lower than those of Cu _x S formed on the polyethylene surface. XRD showed the predomination of Cu _x S phases with low x values.      

5,10:13,14-Disecosteroids: novel modified steroids containing 10- and 9-membered rings

In this paper a synthetic pathway to the modified 5,10:13,14-bisfragmentation cholestane derivatives 8-14 is described. The synthesis involves introduction of the 5α- and 14α-hydroxyl groups in the cholestane molecule and subsequent cleavage of the C(5)-C(10) bond in 5α,14α-dihydroxycholestan-3β-yl acetate (4) with the HgO/I₂ reagent and the C(13)-C(14) bond in the stereoisomeric 14α-hydroxy-5,10-secosteroids 5 and 6 with the Pb(OAc)₄/I₂ reagent. Complete and unambiguous ¹H and ¹³C NMR resonance assignments of the obtained secosteroids, as well as the solution conformations of their 10- and 9-membered rings were determined by extensive analysis of 1D and 2D NMR spectral data. The structures and the solid-state conformations of 5,10-secosteroids 5-7 were confirmed by X-ray analysis. All diseco-compounds have a novel 5,10:13,14-disecocholestane skeleton.     

Micellar Electrokinetic Chromatography of X-Ray Film Developing Baths

A simple and fast micellar electrokinetic chromatographic (MEKC) method for the determination of five main compounds (hydroquinone, metol, phenidone, 2-hydroxy-5-methylaminobenzenesulphonate and 2,5-dihydroxybenzenesulphonate) in X-ray film developing solutions was developed. The optimal conditions for the separation were established by varying the concentration of sodium dodecyl sulfate (SDS), the electrolyte pH and the temperature. Successful results were obtained with a 25mmolL^–1 Tris-phosphate buffer at pH 9.0 in the presence of 50mmolL^–1 SDS using direct UV detection at 214nm. Under these conditions, baseline separation of the five compounds was achieved in less than 8min. The method was validated in terms of precision, linearity, accuracy, and successfully applied to the analysis of X-ray film developing baths.     

Investigation of the decay rate for71Ge in chemical compounds and calibration of the Mössbauer isomer shift of the 67 keV γ-transition of73Ge

Changes of the radioactive decay rate of⁷¹Ge (T _1/2=11.43 days) have been studied experimentally for⁷¹Ge in some compounds of bivalent and quadrivalent germanium. Relative changes Δλ/λ of the electron capture probability have been measured, and the chemical changes Δρ(0) of the electron density at the germanium nuclei have been determined from these measurements. Values for the Mössbauer isomer shift calibration constants for the 67 keV γ-transition of⁷³Ge have been estimated:C=δ/Δρ(0)=(0.061±0.020) mm·s^?1/a.u., Δ〈r ²〉=(21±7)·10^?3 fm², ΔR/R=(6.9±2.3)·10^?4.     

A numerical algorithm for simulation of the Q-switched fiber laser using the travelling wave model

We develop a finite-difference scheme for approximation of a system of nonlinear PDEs describing the Q-switching process. We construct it by using staggered grids. The transport equations are approximated along characteristics, and quadratic nonlinear functions are linearized using a special selection of staggered grids. The stability analysis proves that a connection between time and space steps arises only due to approximation requirements in order to follow exactly the directions of characteristics. The convergence analysis of this scheme is done in two steps. First, some estimates of the uniform boundedness of the discrete solution are proved. This part of the analysis is done locally, in some neighborhood of the exact solution. Second, on the basis of the obtained estimates, the main stability inequality is proved. The second-order convergence rate with respect to the space and time coordinates follows from this stability estimate. Using the obtained convergence result, we prove that the local stability analysis in the selected neighborhood of the exact solution is sufficient.     

Fluorescent Study of Human Blood Plasma Albumin Alterations Induced by Ionizing Radiation

The use of hydrophobic fluorescent probe ABM (benzanthrone derivative) and albumin autofluorescence allowed show conformational alterations in Chernobyl clean-up workers blood plasma. Results obtained in 1996–1997 suggest that acidic expansion of plasma albumin takes place. Latest data (2006–2008) result in splitting of albumin alterations onto two stages - acidic expansion and N-F transition. The N-F transition is accompanied by the blue shift of fluorescence spectra and dehydration of tryptophanyl region of albumin molecule. In 2007 obtained.patterns of ABM spectra had never been previously seen in examined healthy individuals or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc. Patterns of ABM fluorescence spectra are associated with conformational changes of blood plasma albumin. The use of probe ABM and albumin auto-fluorescence allowed show conformational alterations in albumin of Chernobyl clean-up workers blood plasma. It is necessary to note that all investigated parameters significantly differ in observed groups of patients. These findings reinforce our understanding that the blood plasma albumin is a significant biological target of radiation. It may be concluded that fluorescence characteristics are representative of radiation induced albumin alterations and its carrier function.     

On asymptotics of deficit distribution and its moments at the time of ruin

In this paper, we consider the Sparre Andersen insurance risk model with initial surplus x > 0. Let A_x denote the deficit at the time of ruin. Assuming that the tail probabilities of claim size are regularly varying, the second-order asymptotic of the deficit distribution and its moments at the time of ruin are derived.     

Comparison characterization of copper selenide thin layers prepared on polyamide 6 films by sorption-diffusion method

Some earlier synthesized copper selenide (Cu _x Se) layers formed on the surface of polyamide 6 by sorption-diffusion method using potassium selenotrithionate (K₂SeS₂O₆) as precursor of selenium were characterized by the XRD, XPS and SEM methods. According to the results of the SEM studies, the most uniform Cu _x Se layers form at the 2.5 h polyamide seleniumized duration at the temperature of 60°C. The thickness of layers, which dependeds on the duration of seleniumization, changed in the range of 0.8–3.2 µm. The XRD patterns of not previously studied Cu _x Se layers showed their phase composition of six copper selenides: Cu₂Se, two phases of CuSe₂, Cu₃Se₂, berzellianite, Cu_2-x Se, and bellidoite Cu₂Se. Analysis of the XRD and XPS data shows that the macrostructure and composition of the Cu_xSe layers depend on the conditions of formation of these layers.