Synthesis of pyrrolidines,pyrrolines, and pyrroles

As compounds of potential physiological activity, new sulfamide derivatives, Schiffs bases derived from N-arylpyrrolines, are obtained by reacting sulfanilamide, 2-(p-aminobenzenesulfamide) thiazole, 2-(p-aminobenzenesulfamido)-pyrimidine, and 1-phenyl-3-ethyl-4-methyl-5-(p-aminobenzenesulfamido) pyrazole with -(2-chloroethyl)--chlorocrotonaldehyde.For Part XIV see [1].     

Cycles of two-dimensional systems: Computer calculations,proofs, and experiments

One of the central problems in studying small cycles in the neighborhood of equilibrium involves computation of Lyapunov’s quantities. While Lyapunov’s first and second quantities were computed in the general form in the 1940s–1950s, Lyapunov’s third quantity was calculated only for certain special cases. In the present work, we present general formulas for calculation of Lyapunov’s third quantity. Together with the classical Lyapunov method for calculation of Lyapunov’s quantities, which is based on passing to the polar coordinates, we suggest a method developed for the Euclidian coordinates and for the time domain. The calculation of Lyapunov’s quantities by two different analytic methods involving modern software tools for symbolic computing enables us to justify the formulas obtained for Lyapunov’s third quantity. For quadratic systems in which Lyapunov’s first and second quantities vanish, while the third one does not, large cycles were calculated. In the calculations, the quadratic system was reduced to the Liénard equation, which was used to evaluate the domain of parameters corresponding to the existence of four cycles (three “small” cycles and a “large” one). This domain extends the region of parameters obtained by S.L. Shi in 1980 for a quadratic system with four limit cycles.     

The New Strategy for Studying Drug-Delivery Systems with Prolonged Release: Seven-Day In Vitro Antibacterial Action

The new method of antibacterial-drug-activity investigation in vitro is proposed as a powerful strategy for understanding how carriers affect drug action during long periods (7 days). In this paper, we observed fluoroquinolone moxifloxacin (MF) antibacterial-efficiency in non-covalent complexes, with the sulfobutyl ether derivative of β-cyclodextrin (SCD) and its polymer (SCDpol). We conducted in vitro studies on two Escherichia coli strains that differed in surface morphology. It was found that MF loses its antibacterial action after 3–4 days in liquid media, whereas the inclusion of the drug in SCD led to the increase of MF antibacterial activity by up to 1.4 times within 1–5 days of the experiment. In the case of MF-SCDpol, we observed a 12-fold increase in the MF action, and a tendency to prolonged antibacterial activity. We visualized this phenomenon (the state of bacteria, cell membrane, and surface morphology) during MF and MF-carrier exposure by TEM. SCD and SCDpol did not change the drug’s mechanism of action. Particle adsorption on cells was the crucial factor for determining the observed effects. The proteinaceous fimbriae on the bacteria surface gave a 2-fold increase of the drug carrier adsorption, hence the strains with fimbriae are more preferable for the proposed treatment. Furthermore, the approach to visualize the CD polymer adsorption on bacteria via TEM is suggested. We hope that the proposed comprehensive method will be useful for the studies of drug-delivery systems to uncover long-term antibacterial action.     

Solubility in the system Na2Cr2O7 + 2NH4Cl ⇆ (NH4)2Cr2O7 + 2NaCl-H2O

The solubility in the water-salt quaternary reciprocal system Na₂Cr₂O₇ + 2NH₄Cl ⇆ (NH₄)₂Cr₂O₇ + 2NaCl-H₂O has been investigated for the first time at 25, 50, and 75°C. Using a formal analytical model, the boundaries of the phase fields have been determined, and the univariant lines and invariant points have been calculated. The experimental data have been used to calculate the temperature and concentration parameters of the circular isohydric process of potassium dichromate preparation with the participation of ammonium salts as intermediates.     

Consolidation of Bimetallic Nanosized Particles and Formation of Nanocomposites Depending on Conditions of Shock Wave Compaction

Russian Physics Journal - The authors consider and evaluate the physical parameters and regularities of the process of consolidation of Fe–Cu, Cu–Nb, Ag–Ni, Fe–Pb...     

Influence of Substituents in β-Cyclodextrin on the Interaction of Levofloxacin–β-Cyclodextrin Complexes with Liposomal Membrane

Colloid Journal - The effect of substituents (polar CH2CH(OH)CH3, hydrophobic CH3, and charged $${{\left( {{\text{C}}{{{\text{H}}}_{{\text{2}}}}} \right)}_{{\text{4}}}}{\text{SO}}_{3}^{ - }$$ ) in...     

Double Potential Method for Modeling the Internal Flow of a Viscous Incompressible Liquid

Doklady Mathematics - The problem of numerical modelling water purification from iron impurities is considered. The cleaning task is relevant for many industrial applications, including the...     

Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands

We discuss the possibility of optimizing the brightness of luminescence for phenylcarboxylates, naphthylcarboxylates, and indolylcarboxylates of europium and terbium and their adducts with 1,10-phenanthroline and 2,2′-bipyridine by modifying the ligands. We have studied the efficiency of luminescence and luminescence excitation. We consider the effect of blocking energy transfer from the ligands to the Eu³⁺ and Tb³⁺ ions by methylene (-CH₂-) bridges dividing the π-electron system of the ligands into two parts and by the electronacceptor nitro group (-NO₂). We have analyzed the pathways for transfer and degradation of the excitation energy at 77 K and 300 K. From the phosphorescence spectra of gadolinium salts, we have determined the energies of the lowest excited triplet states of the ligands. We consider the effect of the relative positions of the triplet levels of the ligands and the excited levels of the Eu³⁺ and Tb³⁺ ions on the luminescence efficiency. We found channels for dissipation of the excitation energy via the ππ* and nπ* states of the aromatic system of the carboxylate and the NO₂ group. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 48–54, January–February, 2007.     

Investigation of intermolecular interactions in solutions by means of millimeter-wave spectroscopy 5. Positive and negative hydration effects in aqueous solutions of methylureas

A study has been made of the concentration dependence of absorption of radiation at 5 cm^–1 by aqueous solutions of urea and its N-methyl, N,N-dimethyl, N,N'-dimethyl, and tetramethyl derivatives; and their effective hydration numbers have been calculated. The low values obtained for the effective hydration numbers of urea, N-methylurea, and N,N'-dimethylurea are explained by the close mutual approach of the two hydrogen atoms in the trans position relative to the carbonyl group (negative hydration); in the case of the N,N-dimethyl and tetramethyl derivatives, no negative hydration effect is observed. For the tetramethylurea, very definite hydrophobic hydration is observed. On the basis of data obtained on the effective hydration number, an estimate has been made of the relative contents of different conformers of methylurea and N,N'-dimethylurea in solution.For Previous Communication, See [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 321–326, February, 1990.