Hydrodynamic structure of laminar flows with oppositely-swirled coaxial layers

The article is devoted to the theoretical study of hydrodynamics of laminar flows with coaxial layers swirled in opposite directions and moving along the pipe. Such flows in a turbulent range have a wide practical application potential in technologies of dissipation of mechanical energy and mixing multiphase and heterogeneous media in microbiology, chemistry, ecology, heat engineering, power engineering, engine and rocket engineering. The article describes the tensor of viscous tangents (τii) and normal (σii) stresses. The questions of stability of flow according to the Rayleigh (Ra) and Richardson (Ri) criteria are considered. Calculation formulas and graphs of radial-axial distributions of viscous stress components, local stability zones are given, the point of “crisis and decay of the flow” or “vortex breakdown” is indicated. The solutions are obtained in the form of Fourier-Bessel series. The analysis of the hydrodynamic structure of the flow is made

КВАНТОВЫЕ ИНТЕРФЕРОМЕТРЫ ДЛЯ ПРЕДЕЛЬНЫХ ИЗМЕРЕНИЙ

The results of theoretical and experimental studies of quantum interferometer are described. The interferometer based on linear isotropic laser with displacement phased anisotropic plate inside resonator. The perspectives of usage of such resonator as a precession proximity sensor is shownThe necessity of methods and devices for modern medical linear accelerators quality control development is discussed. Quality control is the basic measure of radiation protection of the patients with malignant tumors during radiotherapy. Linear accelerators devices and systems which are influencing on accuracy of dose delivery and dose distribution within treated patients body volumes were considered. Developed methods and devices become a basis of the national protocol for medical linear accelerators quality control which will be used in all oncological clinics of Belarus Republic.Приведены результаты теоретических и экспериментальных исследований квантового интерферометра, представляющего собой линейный изотропный лазер с наклоняющейся фазовой анизотропной пластинкой в резонаторе. Показана перспективность его использования в качестве преобразователя предельно малых угловых перемещений в частоту сигнала биений ортогонально поляризованных мод возбуждающихся в таком лазере

Optical echo-spectroscopy of highly doped Tm:YAG

Two-pulse, stimulated and accumulated photon echoes are investigated for the first time in a highly doped crystal Tm: YAG containing 10 at.% Tm3+. The decay curves of the two-pulse and stimulated photon echoes generated at 793.15 nm on the transition 3H6 (1)-3H4 (1) of the impurity ions are measured in the absence of an applied magnetic field and parameters describing the energy and phase relaxation are determined. The dependence of the intensity of the accumulated photon echo on the number of excitation pulse pairs is investigated. © 2008 by Astro Ltd

Locking of a long-lived photon echo in a nonuniform electric field

A method is developed to control the generation of optical coherent responses in a resonance medium under the action of an external spatially nonuniform electric field. It is shown that a change in the field gradient between the data recording and reading by means of a photon echo suppresses the response generation after the action of the reading pulse, resulting in locking of the data recorded in the medium. The possibilities of using this method in optical memory devices based on a photon echo are discussed

Angular regularities of the photon echo in doped crystals

The regularities of the two-pulse photon echo generation in doped crystals under changes in the angle a between directions of propagation of pumping pulses are investigated theoretically. The explanation of some experimental results obtained by U.P. Wild and coworkers, in particular, the modulation character of the response-intensity dependence on the angle a is presented. Copyright © 1996 by MANK Hayka/Interperiodica Publishing

Formation of photonic echo signals in the presents of a strong concentration quenching effect

The connection between the photonic echo formation in crystals doped by rare-earth elements and the concentration effects was studied. The application of optical echo spectroscopy in studies of garnet crystals with a high content of thulium impurity was demonstrated. By the example of activated crystals of ruby and lanthanum trifluoride, the spectral transformation of the photonic echo signals was analyzed in the present of the concentration quenching effect. © 2009 Allerton Press, Inc

Investigation of femtosecond photon echo in dye-doped polymer film at room temperature

Signals of primary and stimulated femtosecond photon echo were found and investigated at room temperature in a polyvinyl butyral film doped with phthalocyanine molecules. The decay curve of relative intensity and the spectrum of the signal of primary femtosecond photon echo were recorded. The physical mechanism of formation of such signals in a system of impurity centers excited through the phonon wing of the optical absorption band was discussed. © 2007 by Allerton Press, Inc

Low magnetic fields behavior of photon echo in LuLiF4:Er3+

It is reported about the first observation and studying of the photon echo in LuLiF4:Er3+. The energy transition is 4I15/2 → 4F9/ 2 (λ = 6536 Å). The density of ErF3 is 0.025 wt%. The operation temperature is 1.9 K. Measurements were spent at low (up to 1200 Oe) and even zero external magnetic fields. It was studied a behavior of the photon echo intensity versus the magnetic field mgnitude and direction about the crystal axis C and versus the laser pulse separation t12. It was observed an expotential growth and then, after some plateau, an exponential decreasing of the photon echo intensity as a function of magnetic field with increasing of the magnetic field from zero value. The parameters describing the exponential growth and decreasing are not depended on direction of magnetic field. Value of a magnetic field at which the echo intensity accepts the maximum, and quantity of this maximum decrease with increased the pulse sepatation t12 and the angle θ between the magnetic field and crystals axis. The echo intensity expotentially decreases with increased θ. The parameter describing the exponential decreasing is not depended on the magnitude of the field. The echo intensity as a function of pulse separation shows exponential decay. The phase relaxation time is depended on the magnitude and direction of the magnetic field. T2 is equal to 202±16 ns at zero magnetic field. Phenomenological formula is suggested, which qualitatively presents the mentioned dependencies. Polarization properties of the backward photon echo in this crystal are studied also. A graph is presented. Echo size versus magnetic field directed as along optic axis as at an angle of θ = 5° of different values of t12. The color symbols show experimental points. The solid curves were calculated using experession (1). The Y-scale is logarithmic. © 2006 by Astro Ltd. Published exclusively by Wiley-VCH Verlag GmbH & Co. KGaA

Spatial and spectral properties of a photon echo

Spatial and spectral regularities in the formation of photon echo signals are studied. The frequency shift of the signal of a primary photon echo with respect to the carrier frequency of excitation laser pulses that was experimentally observed upon variation of the angle between the wave vectors of the laser pulses is explained. The feasibility of high-resolution angular optical echo spectroscopy is shown

Correlation of nucleotides and carbohydrates metabolism with pro-oxidant and antioxidant systems of erythrocytes depending on age in patients with colorectal cancer

Aim: To examine the relationship between metabolic features of purine nucleotides and antioxidant system depending on the age of patients with colorectal cancer. Materials and Methods: The activity of adenosine deaminase, xanthine oxidase, glutathione peroxidase, superoxide dismutase and glucose-6-phosphate dehydrogenase, the NOx concentration and the oxidative modification of proteins were determined spectrophotometricaly in 50 apparently healthy people and 26 patients with colorectal cancer stage ­III–­­IV, aged 40 to 79 years. Results: Increase of pro-oxidant system of erythrocytes with the age against decrease in level of antioxidant protection in both healthy individuals and colorectal cancer patients was determined. A significant increase of pro­ducts of oxidative proteins modification in erythrocytes with ageing was shown. Statistically significant correlation between enzymatic and non enzymatic markers pro-oxidant system and the activity of antioxidant defense enzymes in erythrocytes of patient with colorectal cancer was determined. Conclusion: Obtained results have demonstrated the imbalance in the antioxidant system of erythrocytes in colorectal cancer patients that improve the survival of cancer cells that is more distinctly manifested in ageing. Key Words: age, colorectal cancer, erythrocyte, nucleotides, antioxidants, oxidative stress