Solvation of molybdenum(O)-diimine-tetracarbonyl complexes

Summary Solubilities of molybdenum(O)-diimine-tetracarbonyl complexes containing pyridyl-primary amine Schiff base or substituted 1,4-diazabutadiene ligands are reported, for a variety of non-aqueous solvents, and for toluene + heptane, toluene + methanol, and methanol-rich methanol + water mixed solvents. Enthalpies and entropies of solution for several of these complexes in a selection of solvents have been derived from temperature variation of solubilities. These results, together with new data on solvent effects on infrared and n.m.r. (¹H, ¹³C, ⁹⁵Mo) spectra and published data on solvatochromism of this family of compounds, are discussed in relation to solvation of these complexes in pure and mixed solvents.     

Alkaloids of and ( )

and provided a variety of and alkaloids as well as novel ring-opened indole alkaloids including leuconolam (6), rhazinilam (8) and 5,21-dihydrorhazinilam (9). Facile acid and base reactions of leuconolam lead to ring reclosure products. Physical and spectral data of norfluorocurarine ( ), norfluorocurarine-N_b-oxide ( ), eburnamine (2), kopsinine (5) and epileuconolam (7) as well as some derivatives of leuconolam are also provided.     

The thermal diffusivity of natural rubber

Measurements of thermal diffusivities of peroxide-cured and sulfur-cured rubbers, over the range 0–100°C and 0–75 phr of carbon, are described. They are based on the asymptotic time dependences of heating and cooling curves, recorded following quenching of the samples into baths at various temperatures. The diffusivities are shown to depend linearly on both temperature and carbon content, to reasonable accuracies over the ranges studied. Some theory bearing on measurement techniques is presented.     

2-pyrazolines on the basis of diarylidene-cyclohexanones. Synthesis and stereochemistry of N-thiocarbamoyl and N-thiazolyl derivatives

In the interaction of N-thiocarbamoylhexahydroindazoles with -bromoacetophenones, the corresponding N-thiazolylpyrazolines are formed. In some cases, the heterocyclization is accompanied by a shift of the double bond and cis-trans isomerization in the pyrazoline ring. A study has been made of the influence of the stereochemistry of these compounds on their spectral and luminescence properties.Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1650–1654, December, 1997.     

Development of Antibacterial,Degradable and pH-Responsive Chitosan/Guar Gum/Polyvinyl Alcohol Blended Hydrogels for Wound Dressing

The present research is based on the fabrication preparation of CS/PVA/GG blended hydrogel with nontoxic tetra orthosilicate (TEOS) for sustained paracetamol release. Different TEOS percentages were used because of their nontoxic behavior to study newly designed hydrogels’ crosslinking and physicochemical properties. These hydrogels were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and wetting to determine the functional, surface morphology, hydrophilic, or hydrophobic properties. The swelling analysis in different media, degradation in PBS, and drug release kinetics were conducted to observe their response against corresponding media. The FTIR analysis confirmed the components added and crosslinking between them, and surface morphology confirmed different surface and wetting behavior due to different crosslinking. In various solvents, including water, buffer, and electrolyte solutions, the swelling behaviour of hydrogel was investigated and observed that TEOS amount caused less hydrogel swelling. In acidic pH, hydrogels swell the most, while they swell the least at pH 7 or higher. These hydrogels are pH-sensitive and appropriate for controlled drug release. These hydrogels demonstrated that, as the ionic concentration was increased, swelling decreased due to decreased osmotic pressure in various electrolyte solutions. The antimicrobial analysis revealed that these hydrogels are highly antibacterial against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The drug release mechanism was 98% in phosphate buffer saline (PBS) media at pH 7.4 in 140 min. To analyze drug release behaviour, the drug release kinetics was assessed against different mathematical models (such as zero and first order, Higuchi, Baker–Lonsdale, Hixson, and Peppas). It was found that hydrogel (CPG2) follows the Peppas model with the highest value of regression (R² = 0.98509). Hence, from the results, these hydrogels could be a potential biomaterial for wound dressing in biomedical applications.