SPECIFIC CHARACTERISTICS OF ELECTRON PARAMAGNETIC RESONANCE SPECTRUM OF DIFFERENT COLORS OF HAIR

In the result of interaction of the metabolic processes of the human organism and external factors free radicals are formed in tissues including hair. An objective assessment of an intensity of this process is possible by means of electronic paramagnetic resonance’s (EPR) signal and its intensity indices. The purpose of the survey was a comparative evaluation of the EPR spectrum’s specificity of black and brown hair and a study of a photo dynamic in the condition of a treating with blue light. The survey was conducted among young volunteers of age 17-21 on the base of their informed consent and with adherence of all bioethical requirements established for this type of research. No single person’s hair involved in the survey was treated with chemical dye or active, specific remedy for hair care. This article analyzes data of young men donors. All measurements were carried out at standard conditions: room temperature (22-240C), humidity - 60-70%, the measurement error - ± 5%. EPR spectrum was determined at the Department of Biophysics,TSU by means of a radio-spectrometer TSR - V. Study results have determined a uniform EPR spectrum and no difference in the intensity of the photoinduced EPR spectrum that indicates the equal concentrations of eumelanin in black and brown hair.

Mineral-polymer composites based on hydroxyapatite with polyvynylpyrrolidon for medicine

Composites of hydroxyapatite (HA) with polyvinylpyrrolidone (PVP) were synthesized by precipitation in water solutions, mass relations of HA/PVP varied in region 3,6-14,5. The composite materials were investigated using XRD, IR, electron paramagnetic resonance (EPR) spectroscopy and transmission electron microscopy (TEM). Based on the TEM results it was found that during calcination of composites at 400 °C small agglomerates consisting of individual crystalline HA particles were formed, resulting in a particle size (according to TEM) slightly larger than coherent scattering region. Using the method of photoinduced EPR spectroscopy confirmed the presence of interaction between HA and PVP. The resulting composites can be used as materials for reconstructive surgery.

Photoinduced Changes in the Charge States of Native Donors and Acceptors in ZnGeP2

Bulk ZnGeP2 (ZGP) crystals grown for high-power tunable mid-infrared laser systems contain large concentrations of three native defects. Using EPR, these three defects have been identified as the Zn vacancy (an acceptor), the phosphorus vacancy (a donor), and the germanium-on-zinc antisite (also a donor). We have studied the wavelength dependence of the photoinduced changes in the EPR signal intensity of the three defect centers using 633 nm and 1064 nm light. We observe a significant increase in the EPR signal under 633 nm light. The 633-nm light also produces an increase in the defect-related 1-R.m absorption band, and we have used a spectrophotometer to measure the spectral shape of the photoinduced change in absorption in this near-IR region. The 633-nm wavelength produces paramagnetic forms of both donor centers, while 1064 nm light only produces the EPR-active center. Time decays of the photoinduced EPR signals have been measured for each of the donors.