µ−spin rotation study of the temperature-dependent relaxation rate of acceptor centers in silicon

Temperature-dependent remanent polarization of negative muons in a silicon crystal doped with phosphorus (3.2 × 10¹², 2.3 × 10¹⁵, and 4.5 × 10¹⁸ cm^?3) and aluminum (2 × 10¹⁴ and 2.4 × 10¹⁸ cm^?3) was examined. Measurements were made over the temperature range 4–300 K in a magnetic field of 2000 G perpendicular to the muon spin. Temperature dependence of the relaxation rate was determined for the magnetic moment of a shallow Al acceptor center in a nondeformed silicon sample, and the hyperfine interaction constant was estimated for the interaction between the magnetic moments of muon and electron shell of the muonic mAl atom in silicon.     

Getting new monomers: Carboxyl bicyclic methacrylates

5-Carboxybicyclo[2.2.1]hept-2-yl acrylate and 5-carboxy-5-methylbicyclo[2.2.1]hept-2-yl methacrylate, which can be used for optical lenses and polymeric materials, were synthesized by reaction of cyclopentadiene and methacrylic acid with a yield of 80.0–90.5%.

     

Electromagnetic fields with 217 Hz and 0.2 mT as hazardous factors for tubulin structure and assembly (in vitro study)

Nowadays exposure to extremely low frequency electromagnetic fields (ELF-EMFs) is an unavoidable fact in human societies. In spite of destructive effects of ELF-EMF such as impression on short-term memory and cognitive performances, neuroprotective and neurogeneration effects of ELF-EMF have been reported. On the other hand, microtubule (MT) proteins, the dynamic cytoskeleton proteins that are mostly located in axons, are able to produce local EMFs and possess key role in memory formation and consciousness. Therefore, MTs have strong potential to be affected by exogenous ELF-EMFs. In the present study, decline of MT polymerization was shown by transmission electron microscopy images and turbidimetry method after exposure to ELF-EMFs with 50, 100, and 217 Hz frequencies at 0.2 mT intensity. Circular dichroism and 8-anilino-1-naphthalenesulfonate (ANS) fluorometry were used to demonstrate the MT secondary and third structural changes. Decrement of MT polymerization through disruption of tubulin native structure, and increasing the β-sheets and random coils were observed in all exposure conditions. Therefore, ELF-EMFs with 50, 100, and specially 217 Hz frequencies at 0.2 mT could lead to disruption of MT functions in the neural cells.     

Synthesis of 8-acetoxytetracyclo[4.4.12.5.17.10.01.6]dodec-3-ene and diesters of C1-C5 acids on its basis

Reaction of vinyl acetate with tricyclo[5.2.1^2.5.1.0^2.6]deca-3,8-diene in the presence of nano-TiO₂ (20 nm) catalyst was studied. 8-Acetoxytetracyclo[4.4.1^2.5.1^7.10.0^1.6]dodec-3-ene was obtained in 88.5% yield. Addition of saturated monobasic acids C₁-C₅ to the obtained unsaturated monoester in the presence of the boron trifluoride etherate catalyst was investigated. Corresponding diesters were obtained in 68.1–93.0% yield. They can be used as the additives to synthetic oils and as components of perfumes.     

Synthesis of co-oligomers of 2-propenylphenol with maleic anhydride and study of products of their transformations with amines as steel corrosion inhibitors

Modification with diethylamine and diethanolamine of co-oligomers of 2-propenylphenol with maleic anhydride yielded water-soluble nitrogen-containing derivatives inhibiting the corrosion of St.3 steel in watersalt solutions.