Superconducting decay length in a ferromagnetic metal

The complex decay length ξ characterizing the penetration of superconducting correlations into a ferromagnet due to the proximity effect is studied theoretically in the framework of the linearized Eilenberger equations. The real part ξ₁ and imaginary part ξ₂ of the decay length are calculated as functions of exchange energy and the rates of ordinary, spin-flip, and spin-orbit electronic scattering in a ferromagnet. The lengths ξ_1,2 determine the spatial scales of, respectively, the decay and oscillation of a critical current in SFS Josephson junctions in the limit of a large distance between superconducting electrodes. The developed theory provides the criteria of applicability of the expressions for ξ₁ and ξ₂ in the dirty and clean limits, which are commonly used in the analysis of SF hybrid structures. The text was submitted by the authors in English.     

Cu-In-O composite thin films deposited by reactive DC magnetron sputtering

Cu-In-O composite thin films were deposited by reactive DC magnetron sputtering at room temperature. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV/vis spectrophotometer, four-probe measurement and Seebeck effect measurement, etc. The samples contain Cu, In and O. The ratios of Cu to In and O to In increase with increase in O₂ flow rates. The ratio of Cu to In is over 1 and this suggests that Cu is in excess. The obtained Cu-In-O thin films are very possibly made of rhombohedral In₂O₃ and monoclinic CuO. Transmittance of the films decreases with increase in O₂ flow rate. The decrease in transmittance results from increase in Cu content in the films. The optical band gap of all the samples is estimated to be 4.1-4.4 eV, which is larger than those of In₂O₃ and CuO. The sheet resistance of the films decreases with increase in O₂ flow rate. Conductivity of the films is a little low, due to the addition of Cu and the poor crystalline quality of the film. The conduction behavior of the films is similar to that of In₂O₃ and the conduction mechanism of Cu-In-O thin films is through O vacancy.     

Selective multiphoton IR dissociation of SF6 molecules under nonequilibrium conditions of a pulsed gasodynamically cooled molecular flow interacting with a solid surface

The process of the isotope-selective multiphoton IR dissociation of SF₆ molecules under the non-equilibrium conditions of a pulsed gasodynamically cooled molecular flow interacting with a solid surface was experimentally studied. The SF₆ molecules dissociate as a result of excitation in a shock wave generated in the flow, in the flow incident onto the sold surface, and in an unperturbed flow (in the absence of the solid). The experiment was based on detecting the luminescence from HF^* molecules (λ ≈ 2.5) μm) accompanying the SF₆ dissociation in the presence of H₂ or CH₄, the emission intensity being a measure of the SF₆ dissociation yield. The molecular beam parameters were studied. The time-of-flight spectra of SF₆ in the flow interacting with the surface were measured under various experimental conditions. The spectral and energy characteristics of the SF₆ dissociation process were determined in the flow interacting with the solid surface and in the unperturbed flow. The dissociation product (SF₄) yield was measured and the coefficient of its enrichment with the ³⁴S isotope was determined. It is demonstrated that, using the shock wave formation, it is possible to increase the efficiency of the isotope-selective dissociation of SF₆ molecules. An explanation of the observed results is proposed. The gas density and temperature in the incident flow and in the shock wave were estimated. The results are analyzed and compared to the other published data on the SF₆ dissociation in a molecular beam.     

Synthesis and characterization of Ni-Zn ferrite nanoparticles

Nickel zinc ferrite nanoparticles Ni_xZn_1−xFe₂O₄ (x=0.1, 0.3, 0.5) have been synthesized by a chemical co-precipitation method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, electron paramagnetic resonance, dc magnetization and ac susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline Ni_xZn_1−xFe₂O₄ nanoparticles. The lattice parameter decreases with increase in Ni content resulting in a reduction in lattice strain. Similarly crystallite size increases with the concentration of Ni. The magnetic measurements show the superparamagnetic nature of the samples for x=0.1 and 0.3 whereas for x=0.5 the material is ferromagnetic. The saturation magnetization is 23.95 emu/g and increases with increase in Ni content. The superparamagnetic nature of the samples is supported by the EPR and ac susceptibility measurement studies. The blocking temperature increases with Ni concentration. The increase in blocking temperature is explained by the redistribution of the cations on tetrahedral (A) and octahedral (B) sites.     

Line parameters and shapes of high clusters: R branch of the ν3 band of CH4 in He mixtures

The IR absorption spectra of CH₄ in pure gas and in mixture with helium were studied in the region of ν₃ band at higher J line clusters R(17)-R(22). The frequencies and intensities of rotation-vibration lines were estimated from the experimental spectra at Doppler shape conditions. The line frequencies and intensities were calculated and used for the attribution of overlapped lines in clusters. The calculated line intensities are close to the experimental values. The calculated frequency structure of the higher J manifolds are somewhat wider than the observed one. The shapes of helium-broadened line clusters were compared with those calculated accounting for line mixing. The relaxation matrix W, which is necessary in shape calculations, was constructed using semiclassical collision rate constants. The calculated shapes are in satisfactory accordance with the measured ones.     

Dynamics of spins in semiconductor quantum wells under drift

The dynamics of spins in semiconductor quantum wells under applied electric bias has been investigated by photoluminescence (PL) spectroscopy. The bias-dependent polarization of PL (P_PL) was measured at different temperatures. The P_PL was found to decay with an enhancement of increasing the strength of the negative bias, with an exception occurred for a low value of the negative bias. The P_PL was also found to depend on the temperature. The P_PL in the presence of a transverse magnetic field was also studied. The results showed that P_PL in the magnetic field oscillates under an applied bias, demonstrating that the dephasing of electron spin occurs during the drift transport in semiconductor quantum wells.     

Anomalous ratios of radioisotopes in PM10 as tracer of global fallout impact in the centre of Mexico

The monitoring and evaluation of radioactive content in samples of PM₁₀ aerosols have been investigated. The specific radioactivity concentrations (SRC) of ²³⁴U, ²³⁵U, ²³⁸U and ²³²Th were determined using inductively coupled plasma-sector field mass spectrometry in 13 samples collected in Mexico City and 8 samples collected in Cuernavaca in the centre of Mexico. The SRC of the radioisotopes analysed in PM₁₀ were larger than those reported in PM_2.5. The enrichment factor was greater than 5, indicating anthropogenic influences in both sites. The activity ratios of these isotopes in the samples were determined. The ²³⁵U/²³⁸U ratio showed variations with respect to the natural value, while the ²³⁴U/²³⁸U and ²³²Th/²³⁸U ratios did not show any secular equilibrium in all sites, corroborating that the increase of uranium is not influenced by natural sources. The annual dose results obtained have no impact on health.     

Effect of ultrasound,heating and enzymatic pre-treatment on bioactive compounds in juice from Berberis amurensis Rupr.

The aim of the study was to assess the influence of ultrasound (frequency 20 kHz, amplitude 70%, power 140 W for 10 min), heating (80 °C, 5 min) and enzymatic pre-treatment of mash (50 °C, Rohapect 10L at a dose of 0.23 g/1000 g, maceration time 60 min) on the yield, the content of phenolic compounds (including anthocyanins), ascorbic acid, and the antioxidative capacity of Berberis amurensis juice. Additionally, the polyphenols profile of this raw material and juices was identified. 25 phenolic compounds were identified in the fruit and 24 in juices. The content of phenolics in the fruit was 636 mg/100 g. Chlorogenic acid, 4-hydroxybenzoate and quercetin-3-O-glicoside were predominant. The content of anthocyanins in the fruit was 217 mg/100 g f.w., where peonidin-3-O-glucoside (98%) was predominant. The content of ascorbic acid amounted to 16.60 mg/100 g. The yield of the barberry juice pressing process ranged from 56% to 60% – there were no differences between the mash treatment methods. The enzymatic and thermal treatment of the mash resulted in the highest content of phenolic compounds in the juice. The sonication resulted in the highest content of anthocyanins, including peonidin-3-O-glucoside, as the main anthocyanin. The thermal treatment of the mash resulted in a lower loss of ascorbic acid than the other methods. The juice from the mash subjected to pectinolysis or heat treatment exhibited the highest antioxidative capacity.     

Numerical evaluation of the 1S12-state radiative level shift

The one-photon self-energy radiative level shift for an electron in a Coulomb potential is evaluated numerically for the $\text{1S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ state. The evaluation is done for values of the nuclear charge Z = 10, 20,…, 110. The errors in the values obtained are estimated to be less than 0.1 %. The results are compared with the results of previous calculations. The evaluation is based on the expressions given in the preceding paper.     

冲击荷载下颗粒物质缓冲性能的试验研究

颗粒物质是一种复杂的能量耗散体系. 颗粒间的摩擦和黏滞作用可使冲击荷载引起的能量有效衰减, 颗粒间的力链结构又可将瞬时局部冲击荷载进行空间扩展和时间延长, 达到良好的缓冲效果. 为研究颗粒物质对冲击荷载的缓冲性能, 本文采用重力作用下球体冲击筒内颗粒物质的试验系统, 研究了筒体底部作用力在颗粒材料、颗粒厚度等因素影响下的变化规律. 试验结果表明: 非规则颗粒具有更加良好的缓冲性能, 粗颗粒的缓冲性能略高于细颗粒. 颗粒厚度H是影响缓冲性能的重要因素, 并存在一个临界厚度H_c. 当H<H_c时, 缓冲性能随H的增加而增强; 当H>H_c时, H对缓冲效果的影响不再显著. 以上研究是在同一冲击能量下进行的, 而对于不同冲击能量下的H_c还需要深入开展. 通过颗粒物质对冲击荷载缓冲性能的试验研究, 可揭示颗粒材料的基本物理力学行为, 为其在缓冲减振领域中的应用提供依据.     

Spray pyrolytic deposition of transparent aluminum oxide (Al2O3) films

Optically transparent Al₂O₃ films has been synthesized, on quartz substrates at 500, 600 and 700 °C, from 0.02 M aluminum acetyl acetonate (Al(acac)₃) in ethanol, by using ultrasonic spray pyrolysis technique. The films synthesized at 500, 600 and 700 °C are amorphous having average particle sizes 27 ± 6, 18 ± 3 and 14 ± 3, respectively. The films are found to be 95% optically transparent in the visible region. The optical transparency of the films in the ultraviolet region is found to increase with increase in deposition temperature. The observed increase in optical band gap and decrease in refractive index is attributed to the decrease in particle size with increase in deposition temperature. The stoichiometry and chemical bonding of the amorphous film studied using XPS and FTIR spectroscopy revealed the presence chemisorbed oxygen.     

Cathodic characteristics of amorphous manganese oxides as lithium secondary battery

The amorphous manganese dioxides were prepared by reduction method using various reagents. The particle size and morphology depended on reducing agents, some of which were aggregated round particles of sub micron order, and the others were small fine fibers like of a few nm in width and several tens nm in length. The former showed low Li-insertion capacity of around 200 mAhg⁻¹, while the latter material showed high capacity of 500 mAhg⁻¹ in the OCV measurements until 1 V vs. Li. The as-prepared MnO₂ contains some amount of water in the structure. The H₂O-free MnO₂ obtained by heat-treatment under high oxygen pressure was inferior in electrode property to MnO₂ containing water in the structure. The H₂O content related to the electrode performance. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.     

Theoretical and experimental IR spectra of binary rare earth tellurite glasses—1

The binary rare earth tellurite glasses (A_nO_m)_x-(TeO₂)_1−x, where x = 0.1 and A = Sm, Ce, La, were prepared by melting the oxides at 800°C for 1 h and quenched rapidly. The IR spectra has been measured in the frequency region 4000-200 cm⁻¹. The main absorption bands in these glasses related to the characteristics of TeO₂. The detected shift in these bands are found to be sensitive to the glass structure. The A-O bond vibration in the glasses has been calculated. The results were interpreted on the basis of stretching force constant of each bond.     

DC-60 heavy ion cyclotron complex: The first beams and project parameters

The construction of the DC-60 Heavy Ion Cyclotron for the Interdisciplinary Scientific Research Complex (ISRC) in Astana started in early 2004. The cyclotron was manufactured and tested at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna. The main units were delivered to Astana and assembled in the ISRC building in the summer of 2006. The cyclotron was turned on in September, 2006. The first heavy ion beams in the whole A/Z and energy ranges were accelerated and extracted in December, 2006. The complex, based on the DC-60 cyclotron, is intended for applied and fundamental research using accelerated heavy ion beams ranging from Carbon to Xenon with energies in the range of 0.34–1.77 MeV/nucleon, as well as for experiments on the channel of low energy ion beams, where the ion extraction voltage supplied by the ECR source reaches 25 kV. The energy variation of the accelerated ions is accomplished by changing the ion charge. The possibility of smoothly tuning the ion energy by ±30% of its nominal value can be seen by changing the cyclotron magnetic field. Within the framework of commissioning the DC-60 cyclotron, a number of experiments were carried out with accelerating charged particle beams in the main points of the working diagram

Fabrication and characterization of Zn1−xAlxO nanoparticles by DC arc plasma

In this paper we have introduced a simple method for the fabrication of aluminum doped zinc oxide (AZO) nanoparticles. The Zn_1−xAl_xO nanoparticles with different concentrations of Al (x=0.01, 0.03, 0.06, 0.09, 0.12) were fabricated successfully by this method. The samples were analyzed by the use of several techniques such as SEM, EDX, XRD, PL and UV-vis spectroscopy. The SEM images showed that the fabricated nanoparticles had spherical shapes. The XRD patterns of the samples indicated that the Al atoms substituted in the Zn positions in the crystal lattice of ZnO and there were some changes in the lattice parameters. A blue shift in the λ_max of the absorption and a red shift in the λ_max of the emission were observed. The results also indicated that the amount of shifts had a direct relationship with the changes in the lattice parameters.     

Luminescence of biologically active 24-epicastasterone and a model compound

Biologically active brassinosteroid 24-epicastasterone, ring B of which contains a C=O group and has the nπ*-configuration for a low-lying electronic excited state, exhibits rapid fluorescence. The wavelengths of the fluorescence maxima of the steroid dissolved in hexane and acetonitrile are equal to 332 and 394 nm, respectively. The fluorescence lifetime of the steroid dissolved in acetonitrile is τ = 9.9 nsec. Solutions of 24-epibrassinolide do not luminesce. The long-wavelength electronic absorption band λ_max^abs = 340 nm in the absorption spectrum of an ethanol solution of model compound 2, ring D of which contains a C=O group π*-conjugated with the C=C double bond of ring C, like in the spectrum of the steroid, has a low extinction coefficient. An ethanol solution of 2 does not fluoresce. 24-Epicastasterone at 77 K in ethanol solution exhibits phosphorescence with λ_max^phos = 447 nm. The phosphorescence decay is exponential with τ = 0.79 msec. Compound 2 also phosphoresces. The phosphorescence spectrum of its ethanol solution has a maximum at 490 nm. The phosphorescence decay is nonexponential in the early stage. The phosphorescence lifetime is 25 msec in the exponential decay region. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 182–186, March–April, 2008.     

Infrared Study of Hydrogen Bond Complexes Involving 1,3-Dimethyl, 2-imidazolidinone and Hydroxylic Derivatives

The hydrogen bond complexes between 1,3-dimethyl, 2-imidazolidinone (DMI) and phenols are investigated in carbontetrachloride and in 1,2-dichloroethane (DCE) by infrared spectrometry. The thermodynamic and spectroscopic data show that DMI possesses a good proton acceptor ability. The thermodynamic parameters are greater in CCl₄ than in DCE while the Δ _VOH values shown a reverse trend. The shift of the ^VS OH stretch in the DMI-water complex is also greater in DCE than in carbontetrachloride. The differences are discussed in terms of specific solvation effects and of different polarity of the two solvents.     

Electrochemical characteristics of amorphous silicon thin film electrode with fluoroethylene carbonate additive

The electrochemical and compositional changes of a solid electrolyte interphase (SEI) layer formed on the surface of silicon thin film are investigated in order to determine the effect of the content of fluoroethylene carbonate (FEC) additive in the electrolyte. Comparisons are made with FEC-free electrolyte, in which the major components are (CH₂OCO₂Li)₂ and Li₂CO₃. The (CH₂OCO₂Li)₂ and Li₂CO₃ of the SEI layer in the FEC-containing electrolyte decreases, and polycarbonate and LiF increase relatively with the repression of –OCO₂Li groups. The additive affects the composition of the SEI layer, which leads to lower resistance. The electrochemical performance regarding cycle retention, coulombic efficiency, rate capability, and discharge capacity in the FEC-containing cell are significantly enhanced compared to that of the FEC-free electrolyte. The observed optimum FEC concentration in the electrolyte is 1.5%, due to the reduced charge transfer and SEI resistance in our experimental range.     

Mechanical response of proton beam irradiated nitinol

The present investigation deals with the study of mechanical behavior of proton beam irradiated nitinol at room temperature. The specimens in austenitic phase were irradiated over periods of 15, 30, 45 and 60 min at room temperature using 2 MeV proton beam obtained from Pelletron accelerator. The stress-strain curves of both unirradiated and irradiated specimens were obtained using a universal testing machine at room temperature. The results of the experiment show that an intermediate rhombohedral (R) phase has been introduced between austenite and martensite phase, which resulted in the suppression of direct transformation from austenite to martensite (A-M). Stresses required to start R-phase (σ_RS) and martensitic phase (σ_MS) were observed to decrease with increase in exposure time. The hardness tests of samples before and after irradiation were also carried out using Vickers hardness tester. The comparison reveals that the hardness is higher in irradiated specimens than that of the unirradiated one. The increase in hardness is quite sharp in specimens irradiated for 15 min, which then increases linearly as the exposure time is increased up to 60 min. The generation of R-phase, variations in the transformation stresses σ_RS and σ_MS and increase in hardness of irradiated nitinol may be attributed to lattice disorder and associated changes in crystal structure induced by proton beam irradiation.