Femtosecond laser plasma in CaF<Subscript>2</Subscript> crystal microchannel and effective generation of characteristic X-ray radiation

The dependence of the characteristic X-ray radiation yield from CaF₂ crystal on the formed microchannel depth under highly intensive (I ∼ 3 × 10¹⁵ W/cm²) laser pulses with different contrast was obtained. The maximum of the characteristic X-ray radiation yield at these experimental conditions corresponded to the microchannel depth of 30–50 μm. The efficiency of the laser radiation conversion to the characteristic X-ray radiation increased from 6 × 10⁻⁸ for the surface up to 10⁻⁷ in the microchannel. The dependence of the characteristic X-ray radiation yield on the viewing angle showed that the source of X-ray radiation was located near the surface inside the microchannel.     

Vibrational Spectra and Steric Hindrance in Trichlorophospkazoperchloroalkyl Molecules

Abstract

Recently the IR spectra of trichlorophosphazoperhaloalkyls, CI_3P[dbnd]NR_Hal, were studied,¹and the position of P[dbnd]N frequencies in the range of 1300-1500cm^?1 and those of C-N within the range of 900-1000cm^?1 were found to depend to a great extent upon the nature of the groups attached to the nitrogen atom.     

Exchange bias in the IrMn/Co structures with alternative sequences of antiferromagnetic and ferromagnetic layers

JETP Letters - The magnetic properties of Mo/IrMn/Co/Mo/SiO2/Si structures with alternative sequences of the antiferromagnetic and ferromagnetic layers have been studied by measuring the angular...     

External electric field effect on electronic properties and charge transfer in CoI2/NiI2 spinterface

Electronic structure and spin-related properties of CoI₂/NiI₂ heterostructure were studied by means of density functional theory. It was shown that the electronic structure at the Fermi level can be characterized by a band gap. The effect of the external electric field on charge transfer and electronic properties of the CoI₂/NiI₂ interface was investigated, and it was found that band gap width depends on the strength of the applied electric field, switching its nature from semiconducting to a half-metallic one. An easy control of the electronic properties and promising spin-polarized nature of the CoI₂/NiI₂ spinterface allows the heterostructure to be used in spin-related applications.     

Ultralow-birefringence measurement in optical fibers by the twist method

We describe a simple method for measuring ultralow birefringence in optical fibers. It allows one to measure birefringence in the range of 4x10(-6) 1.25x10(-8) , which corresponds to the 0.2580-m range of the polarization beat length at the wavelength of 1 microm . A fiber section of a length shorter than the polarization beat length can be used for measurement. The measuring procedure involves measurement of the light intensity only and does not require an analysis of the light-polarization state. Experimental results for an optical fiber with a beat length of 1.9m are presented.     

Comparing the Impact of NIR,Visible and UV Light on ROS Upregulation via Photoacceptors of Mitochondrial Complexes in Normal,Immune and Cancer Cells

The effect of UV/visible/NIR light (380/450/530/650/808/1064 nm) on ROS generation, mitochondrial activity and viability is experimentally compared in human neuroblastoma cancer cells. The absorption of photons by mitochondrial photoacceptors in Complexes I, III and IV is in detail investigated by sequential blocking with selective pharmaceutical blockers. Complex I absorbs UV/blue light by heme P450, resulting in a very high rate (14 times) of ROS generation leading to cell death. Complex III absorbs green light, by cytochromes b, c1 and c, and possesses less ability for ROS production (seven times), so that only irradiation lower than 10 mW cm⁻² causes an increase in cell viability. Complex IV is well-known as the primary photoacceptor for red/NIR light. Light of 650/808 nm at 10–100 mW cm⁻² generates a physiological ROS level about 20% of a basal concentration, which enhance mitochondrial activity and cell survival, while 1064 nm light does not show any distinguished effects. Further, ROS generation induced by low-intensity red/NIR light is compared in neurons, immune and cancer cells. Red light seems to more rapidly stimulate ROS production, mitochondrial activity and cell survival than 808 nm. At the same time, different cell lines demonstrate slightly various rates of ROS generation, peculiar to their cellular physiology.     

Projective functors for algebraic groups

We investigate the regular subquotient category introduced by Soergel in [W. Soergel, On the relation between intersection cohomology and representation theory in positive characteristic, J. Pure Appl. Algebra 152 (1–3) (2000) 311–335]. A detailed study of projective functors enables one to relate those categories for semi-simple algebraic group G and its subgroup schemata G_rT. As an application we derive some information about the characters of tilting modules for G.     

Diagnostic Value of Short and Long Echo Time in <Superscript>1</Superscript>H-MRS for Patients with Multiple Sclerosis

The quality of the signal received from metabolites in ¹H-magnetic resonance spectroscopy (MRS) directly depends on physical parameters of the impulse sequence used, namely on Time of Echo (TE). We compare MRS (Achieva 3T PRESS ¹H-MRS (TE = 53 and 144 ms, TR = 2000 ms) data acquired in supraventricular white matter and medial cortex at two various TE (53 and 144 ms) for patients with the multiple sclerosis (25 patients with the confirmed diagnosis of relapsing-remitting multiple sclerosis and 20 patients with the diagnosis of secondary progressive multiple sclerosis) and control group (21 healthy volunteers, comparable on age), to evaluate advantages and disadvantages of these two Echo Time in clinical practice.     

Microspectral analysis of dentine with femtosecond laser induced plasma

Microspectral analysis of dentine plasma produced by femtosecond laser radiation with intensities of I ～ 10¹³?10¹⁵ W/cm² in ambient atmosphere has been measured. C, O, Ca, Zn, Na, and Cu spectral lines were identified. The X-ray radiation with energies E > 30 keV has been observed upon laser beam intensities of I ～ 5 × 10¹⁵ W/cm².