Influence of the Degree of Deacetylation of Chitosan and BMP-2 Concentration on Biocompatibility and Osteogenic Properties of BMP-2/PLA Granule-Loaded Chitosan/β-Glycerophosphate Hydrogels

Compositions based on chitosan/β-glycerophosphate hydrogels with highly porous polylactide granules can be used to obtain moldable bone graft materials that have osteoinductive and osteoconductive properties. To eliminate the influence of such characteristics as chain length, degree of purification, and molecular weight on a designed material, the one-stock chitosan sample was reacetylated to degrees of deacetylation (DD%) of 19.5, 39, 49, 55, and 56. A study of the chitosan/β-glycerophosphate hydrogel with chitosan of a reduced DD% showed that a low degree of deacetylation increased the MSCs (multipotent stromal cells) viability rate in vitro and reduced the leukocyte infiltration in subcutaneous implantation to Wistar rats in vivo. The addition of 12 wt% polylactide granules resulted in optimal composite mechanical and moldable properties, and increased the modulus of elasticity of the hydrogel-based material by approximately 100 times. Excessive filling of the material with PLA (polylactide) granules (more than 20%) led to material destruction at a ~10% strain. Osteoinductive and osteoconductive properties of the chitosan hydrogel-based material with reacetylated chitosan (39 DD%) and highly porous polylactide granules impregnated with BMP-2 (bone morphogenetic protein-2) have been demonstrated in models of orthotopic and ectopic bone formation. When implanted into a critical-size calvarial defect in rats, the optimal concentration of BMP-2 was 10 μg/mL: bone tissue areas filled the entire material’s thickness. Implantation of the material with 50 μg/mL BMP-2 was accompanied with excessive growth of bone tissue and material displacement beyond the defect. Significant osteoinductive and osteoconductive properties of the material with 10 μg/mL of BMP-2 were also shown in subcutaneous implantation.     

A new, fast and efficient synthesis of 3-aryl indenones: intramolecular cyclization of 1,3-diarylpropynones in superacids

1,3-Diarylpropynones were cleanly converted to the corresponding 3-arylindenones in various superacidic media. This new, simple, one-pot reaction proved to be efficient (yields up to 95%) and very fast (reaction time less than 30 min).     

Alkyl 3-amino-5-aryl-2-benzoyl-5-oxo-2-pentenoates as new chelating ligands and reagents of heterocyclic synthesis

A method for the synthesis of alkyl 3-amino-5-aryl-2-benzoyl-5-oxo-2-pentenoates from Ni chelates of alkyl benzoylacetates and aroylacetonitriles was proposed. The compounds obtained were used for preparation of ethyl 4-amino-6-aryl-2-phenylnicotinates and Ni and B chelates.     

Two-dimensional site-bond percolation as an example of a self-averaging system

The Harris-Aharony criterion for a static model predicts that if a specific heat exponent α>0, then this model does not exhibit self-averaging. In the two-dimensional percolation model, the index α= ?1/2. This means that, in accordance with the Harris-Aharony criterion, the model can exhibit self-averaging properties. We study numerically the relative variances R _M and R _χ for the probability M of a site belonging to the “infinite” (maximum) cluster and for the mean finite-cluster size χ. It was shown that two-dimensional site-bond percolation on the square lattice, where the bonds play the role of the impurity and the sites play the role of the statistical ensemble over which the averaging is performed, exhibits self-averaging properties.     

A Convenient Method for the Preparation of Linear Furoquinolin-2-ones

Fries rearrangement of 7-acetoxy-4-methylquinolin-2-one and subsequent condensation of the 6-acetyl-7-hydroxy-4-methylquinolin-2-one obtained with -chloro ketones gives a series of furo[3,2-g]quinolin-7-ones.     

Preparation of rare metallic actinides (248Cm,249Bk,249Cf) and investigation of their crystal structure

²⁴⁸Cm and²⁴⁹Bk metals were prepared by thermal reduction of their oxides with thorium and metallic²⁴⁹Cf with metallic lanthanum. These rare actinide samples of 1.0 mg in mass were thin layers on a flat substrate and were investigated by X-ray technique. Dhcp lattice parameters of -Cm, -Bk and -Cf as main phases in X-ray diagrams are presented. The effect of impurities on the -Cm lattice parameters is shown. Fcc lattices for the high temperature form of Cm metal (-Cm) with a=0.4933 nm, and of Cm and Bk monoxides (a=0.502–0.504 nm and a=0.5002 nm, respectively) have been observed. Thermal expansion coefficients for -Cm and -Bk at 80–300 K were calculated. Identification problems of fcc lattices and oxidation features of metals prepared are discussed.     

Separation of pyrimidine deoxyribooligonucleotides according to length and composition using thin-layer chromatography on deae-cellulose.

A procedure has been developed for the fractionation of pyrimidine deoxyribo-oligonucleotides, PynPn+1, according to length and composition using ascending thin-layer chromatography on DEAE-cellulose. The separation of oligonucleotides according to length (n=1-7) into individual isopliths was carried out using a linear 0-0.35 M sodium chloride gradient in 0.01 M sodium acetate buffer of pH 5.1-5.3 and 5 M urea. Then the oligonucleotides of individual isopliths were separated according to composition using the same gradient of sodium chloride in 0.01 M sodium acetate or sodium citrate buffer of pH 3.2. The procedure can be used for rapid fractionation (2-3 h) and serial determination of the frequencies of pyrimidine sequences differing in length and composition in DNAs of various origin. The procedure can be used for both preparative and analytical applications. It was employed to study the distribution of 5-methylcytosine in pyrimidine isopliths of some DNAs.     

Investigation of primary cosmic rays at the Moon’s surface

The possibility of experimentally studying primary cosmic rays at the Moon’s surface is considered. A mathematical simulations of showers initiated in the lunar regolith by high-energy particles of primary cosmic rays is performed. It is shown that such particles can in principle be recorded by simultaneously detecting three components of backscattered radiation (secondary neutrons, gamma rays, and radio emission).     

A high spectral resolution spectrograph with fiber input for the Big Azimuthal Telescope of SAO RAS. Improvement of the spectral module

The paper presents a critical analysis and modernization of separate elements of the optical layout of a high-resolution spectrograph with fiber input for the Big Azimuthal Telescope of the Special Astrophysical Observatory. The modernization is directed mainly at enhancing the light efficiency and making it possible to produce the spectrograph using domestic manufacturers. Renovated versions of the cross-dispersion grism, the projection camera, and the overall characteristics of the system are presented. The resulting efficiency of the whole instrument is given.

     

Fused Fluorinated Bis-β-diketones and Luminescent-Spectral Properties of Their Complexes with Europium

Russian Journal of General Chemistry - Claisen condensation of diacetylated fused aromatic and heteroaromatic compounds (fluorene, dibenzofuran, dibenzothiophene, or carbazole) with...