New 5-arylamino-4-(5-nitrofuran-2-yl)pyrimidines as promising antibacterial agents

A facile synthetic approach to 5-arylamino-4-(5-nitrofuran- 2-yl)pyrimidines by the Buchwald–Hartwig cross-coupling with various anilines has been developed. All synthesized compounds demonstrated a significant level of in vitro antibacterial activity against Neisseria gonorrhoeae, Streptococcus pyogene and Staphylococcus aureus, including their drug-resistant strains, which is much higher than that of the commercial drug Spectinomycin.     

Biocompatibility of the Ti<Subscript>81</Subscript>Nb<Subscript>13</Subscript>Ta<Subscript>3</Subscript>Zr<Subscript>3</Subscript> Alloy

Titanium-based alloy with low-toxic metals such as niobium, tantalum and zirconium (TiNbTaZr) was manufactured. The primary weight percentages of elements used for fusion were: titanium, 65%; niobium, 20%, tantalum, 10%; and zirconium, 5%. The TiNbTaZr alloy had a yield strength of about 550 MPa, a tensile strength of about 700 MPa, and a Young’s modulus of about 50 GPa, that is, it was comparable with Nitinol. A primary study of the biocompatibility of the TiNbTaZr alloy using the SH-SY5Y cells showed that the alloy did not have significant short-term toxicicity towards the cells incubated on the alloy surface. The number of non-viable cells was 2.5 times lower on the TiNbTaZr alloy than on Nitinol. The biocompatibility of TiNbTaZr was more pronounced than that of the Nitinol reference sample.     

High-temperature carbonization of humic acids and a composite of humic acids with graphene oxide

Humic acids (HAs) isolated from high-moor peat have been studied by magic-angle spinning solid-state nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and Raman spectroscopy. A composite of HAs with graphene oxide (GO) has been prepared for the first time, and the thermal carbonization (900°C) of both HAs and the HA–GO composite has been carried out. With the use of mass spectrometry, it has been found that CO₂ and H₂O molecules are mainly released from HAs into the gas phase at a low temperature (to 150°C). At higher temperatures, carbon monoxide and different low-molecular-weight hydrocarbons also begin to be released. From microscopic examinations, it follows that HA forms small agglomerates with sharply outlined edges as a result of carbonization, whereas the composite forms only large aggregates.     

Effect of solvents on properties of polymer gel-electrolyte based on polyester diacrylate

New polymer gel electrolytes based on polyester diacrylates and LiClO₄ salt solutions in organic solvents are developed for lithium ion and lithium polymer batteries with a high ionic conductivity up to 2.7 × 10^?3 Ohm^?1cm^?1 at the room temperature. To choose the optimum liquid electrolyte composition, the dependence is studied of physico-chemical parameters of new gel electrolytes on the composition of the mixture of aprotic organic solvents: ethylene carbonate, propylene carbonate, and λ-butyrolacton. The bulk conductivity of gel electrolytes and exchange currents at the gel electrolyte/Li interface are studied using the electrochemical impedance method in symmetrical cells with two Li electrodes. The glass transition temperature and gel homogeneity are determined using the method of differential scanning calorimetry. It is found that the optimum mixture is that of propylene carbonate and λ-butyrolacton, in which a homogeneous polymer gel is formed in a wide temperature range of ?150 to +50°C.     

Synthesis of new fluorine-containing derivatives of quinoxaline 1,4-dioxides and condensed systems derived from them

The Beirut reaction of 5,6-difluorobenzofuroxan with 1,3-diketones, β-ketoesters, and amides produces 6,7-difluoroquinoxaline 1,4-dioxides. The condensation of 2-ethoxycarbonyl-6,7-difluoro-3-methylquinoxaline 1,4-dioxide is studied. Fluorinated furo[3,4-b]- and pyrrolo[3,4-b]quinoxaline 4,9-dioxides are synthesized and further functionalized by nucleophilic substitution of fluorine and reduction of the N-O bond. Dedicated to Professor Henk van der Plas on his 70th birthday. Ural's State Technical University, Ekaterinburg 62002, Russia; e-mail: azine@htf.rcupi.e-burg.su. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 520–531, April, 1999.     

Growth and Study of Properties of Mixed Crystals (NH4)2NixCo1 –x(SO4)2 · 6H2O

Crystallography Reports - Mixed crystals (NH4)2NixCo1 –x(SO4)2 · 6H2O have been grown from aqueous solutions of different compositions by reducing the solution temperature in two growth...