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This paper discusses the physics of the influence of a strong magnetic field H on the high T c metal ceramic critical current J c . The problem of boundary conditions for a surface current value in hard superconductors is analyzed. It is shown that if Abrikosov vortices in granules are rigidly pinned, the J c vs H dependence has a plateau region of relatively constant critical current. The hysteresis of ceramic critical current is calculated on the basis of the Josephson weak link model.

The following problem is considered. Let be a finite -fold sequence of nonnegative numbers such that if then , and . The purpose of the work is to give best possible upper estimates of the norms and with 0$ SRC=http://ej.iop.org/images/1468-4802/78/2/A01/tex_sm_3469_img9.gif/> in terms of the coefficients . The Dirichlet kernels with present a particular case of .Bibliography: 14 titles.

A new model is developed to describe the properties of a Josephson junction critical current in a strong magnetic field. A comparison with experiments shows the possibility of the existence of a surface barrier to the Abrikosov vortex motion in YBCO-124 metalceramics. Characteristic features of this barrier appear in the abnormal hysteresis loop of the transport critical current.

1. The device allows rapid (2 min) determination of mechanical impedance of the entire respiratory system, upper respiratory tract, and the entire respiratory system as corrected by upper respiratory tract at frequencies of 7, 10, 13, 16, and 19 Hz.

Double cyclization of N-acetyl-2-(cyclopent-2-enyl)aniline initiated by ozonolysis resulted in 9-acetyl-2-hydroxy-2,3,4,4a,9,9a-hexahydropyrano[2,3-b]indole.

The purpose of this study was analysis of relationships between parameters of metabolic gases transportation system in men or animals and dynamics of gases contents in alveolar and box spaces. The analysis is based on lumped parameter mathematical modeling. The full system of equations and reductions of governing equations are considered. The modeling is used for interpretation of experimental data on O2, CO2 and CO contents in a chamber with a Macaca mulatta monkey.

CONTENTSIntroductionChapter I. Convergence of rectangular partial sums ?1. Results on the almost everywhere convergence of Fourier series of integrable functions ?2. The almost everywhere convergence of Fourier series of functions from ?3. A brief survey of new results on the convergence of rectangular partial sums in various metricsChapter II. New results on rectangular means of multiple Fourier seriesChapter III. Dirichlet kernels ?1. Lebesgue constants and norms of some trigonometric polynomials ?2. Asymptotic behaviour of Dirichlet kernelsChapter IV. Uniqueness problems for multiple trigonometric series (rectangular partial sums)Chapter V. Problems of localization for rectangular partial sumsChapter VI. Special classes of multiple trigonometric series ?1. Series with monotone coefficients ?2. Multiple lacunary series ?3. Fourier series of piecewise monotone functions of several variablesChapter VII. A definition of convergence of multiple seriesChapter VIII. Conjugate series and conjugate functions of several variables ?1. Conjugate series and conjugate functions in , ?2. The conjugation operator in the space ?3. Multidimensional analogues of Plessner's theoremChapter IX. Representation of functions by trigonometric series and correction of functionsChapter X. Fourier coefficients ?1. Cantor-Lebesgue and Denjoy-Luzin theorems ?2. New results on the absolute convergence of Fourier series ?3. Transformations of Fourier coefficients and other resultsReferences

Tunneling characteristics of high-T c oxide superconductor Bi-Sr-Ca-Cu-O have been measured in the wide bias voltage and temperature range. Near zero bias voltage tunneling conductivity σ (U) is expressed by the U1/2 at low temperature, which goes to the linear one at U > 100 mV . Background conductivity metaloxide is determined by Shottky barrier on surface high-T c . It has been found that the peaks of σ (U) curves for low-ohmic contacts are well described theoretical model of destruction of superconductivity of the intergranular weak links. Parameters of these links are estimated. Zero bias anomaly conductivity peaks are explained by breakdown weak links with small critical current.

The author discusses classes of periodic functions of variables that are either piecewise monotonic or piecewise monotonic in the sense of Hardy, and clarifies the connections, for such functions, between the property of belonging to space, , and the convergence of series of their trigonometric Fourier coefficients, We establish the existence, when 1$ SRC=http://ej.iop.org/images/0025-5726/39/3/A02/tex_im_2240_img5.gif/>, of certain results that differ from the one-dimensional case.

Let be a natural number, . Then we shall say that a function of period in each variable is monotonic if there exist an open rectangular parallelepiped and numbers , each of which is either 0 or 1 , such that for , and if , and for , then .The main result of this paper is that the multiple trigonometric Fourier series of an integrable monotonic function is Pringsheim convergent almost everywhere, in particular at each point of continuity of in the interior of .

The purpose of this study was a development of a technique of noninvasive estimation of a biological effect of radiation exposure in monkeys by virtue of a laser measurement of endogenous CO content in exhaled air and technique's testing in the experiment with acute radiation exposure. A control and a test groups consisted of two rhesus monkeys each. The test group was exposed to 6 hours radiation exposure with 1.2 Gy dose produced by gamma-rays. We measured the changes of endogenous CO excretion in animals located in the opened system of the box by virtue of the developed laser based CO-meter. We found that CO excretion increased on the 3rd day after radiation exposure. Consumption of oxygen and excretion of carbon dioxide did not change after the exposure.

Narrow-gap higher mobility semiconducting alloys In_{1-x}Mn_{x}Sb were synthesized in polycrystalline form and their magnetic and transport properties have been investigated. Ferromagnetic response in In_{0.98}Mn_{0.02}Sb was detected by the observation of clear hysteresis loops up to room temperature in direct magnetization measurements. An unconventional (reentrant) magnetization versus temperature behavior has been found. We explained the observed peculiarities within the frameworks of recent models which suggest that a strong temperature dependence of the carrier density is a crucial parameter determining carrier-mediated ferromagnetism of (III,Mn)V semiconductors. The correlation between magnetic states and transport properties of the sample has been discussed. The contact spectroscopy method is used to investigate a band structure of (InMn)Sb near the Fermi level. Measurements of the degree of charge current spin polarization have been carried out using the point contact Andreev reflection (AR) spectroscopy. The AR data are analyzed by introducing a quasiparticle spectrum broadening, which is likely to be related to magnetic scattering in the contact. The AR spectroscopy data argued that at low temperature the sample is decomposed on metallic ferromagnetic clusters with relatively high spin polarization of charge carriers (up to 65% at 4.2K) within a cluster., Comment: 19 pages, 9 figures, 1 table

The efficiency of high pressure technique for the evidence of the Josephson nature of the intergranular contacts in metal ceramics has been demonstrated. With this technique it has been found that the abnormal hysteresis in fields of the order of tens kOe was not connected with the short-circuited contacts between the granules. The reason for the hysteresis lies in the ambiguity of the magnetization of the granules versus the change in the magnetic field direction. The critical current stability of the Josephson conteacts to high magnetic fields is due to both the inhomogeneity of the contacts and the existence of Abrikosov vortices within the superconducting electrode links.

The tunneling density of states of planeNS sandwiches with a normal interlayer thicknessd is calculated. The self-consistent account of the coordinate dependence of the order parameter both inN andS metals as well as of elastic scattering from impurities was considered. The range of the sandwich parameter values is found, where the density of states can have a double-peak structure even at perfect interface. This double-peak structure was obtained earlier in the tunnel McMillan model, which assumed the presence of the tunneling barrier between theN andS layers. Thus, the Andreev reflection effects can result in a large variety of density of states of thickNS sandwiches and, in particular, to the double-peak structure.

The thermal conversions of three-dimensional polymethylsilsesquioxane in the temperature interval 197–465°C have been investigated by isothermal TGA and IR spectroscopy. In this temperature interval there is condensation of the residual SiOH groups formally obeying the patterns of second order reactions with an activation energy 34 kJ/mole and rearrangement of the cyclic siloxane fragments with increase in the relative proportion of cycles of larger size.

The critical current density of Y-based and Bi-based high-T c superconductors has been measured under pressure. The substantial increase of j c with pressure is found. The results of our measurements can be explained if the sample is regarded as a network of S-N-S junctions with arbitrary parameters. These junctions can be formed by integrain layers and/or twin boundaries.

A new method is proposed for determining the composition of multicomponent polymer systems by solving a set of normal equations for the unknown fractions of individual components present in the system, where the necessary sums of calculated characteristics and the corresponding experimental values are the known parameters. The efficiency of the new method is shown by an example where the composition of solid products resulting from thermal and thermo-oxidative degradation of poly(dimethylsilsesquioxane) has been determined.

Tunneling experiments with Bi2223 reveal that a decrease in the carrier concentration shifts the boundary frequency ω0 of the cuprate phonon spectrum towards higher frequencies from ω0=98 mV(Tc=113 K) to ω0=106 mV(Tc=107 K) with an insignificant suppression of the energy gap parameter Δ.

A “softening” of the high-frequency modes of the phonon spectrum is detected under pressure. These modes correspond to breathing oxygen modes and to other vibrational modes of Cu–O. The obtained results explain the observed increase in the ratio 2Δ/kTc within the framework of the strong electron–phonon interaction model.

Pronounced softening of the high-frequency part of the phonon spectrum at high pressures is observed by means of tunneling spectroscopy. As the pressure is increased, the characteristic frequencies of the spectrum at ħΩ>60 mV decrease at the rate d ln(ħΩ)/dP≈(−6.5±0.5)×10−3 kbar−1. On the other hand, hydrostatic pressure causes the low frequencies of the phonon spectrum of Bi 2223 metal oxide to shift very slightly toward higher energies, consistent with Raman spectra.

Improved tunneling spectroscopy on BSCCO(2212) single crystal provided certain spectrum of quasiparticles that mediate the strong Cooper pairing, and it reveals that optical phonons due to the oxygen oscillations in and around the [CuO2] net-plane play a significant role. The elucidated electron-phonon coupling intensities α2F(ω) shows an exceeding peak at 72 meV of the breathing mode relating to the charge fluctuations rather than at 35 meV of the B1g mode which may enhance the spin correlation. Beyond the single phonon energy range ħωD, further significant spectrum peaks was observed and their characteristic energies were assigned in terms of ɛ0 = 72 meV as nɛ0 + ħωph.

Ozonolysis of N-acyl-2-(1-methylbut-2-enyl)- and N-acyl-2-(cyclopent-2-enyl)anilines followed by treatment with NaBH4 afforded the corresponding 2-(2-hydroxyethyl-1-methyl) and 2-(1,5-dihydroxypent-2-yl) derivatives. The reaction can be directed to indole derivatives by varying the nature of both the acyl group and reducing reagent.

The authors have measured the pressure effects on the superconducting Tc and the current density Ic of the YBaCuO (123) phase and the BiSrCaCuO (2223) phase up to 10 kbar. They have found that for Bi ceramics the increase in Jc with pressure is related to the Tc change, while for YBCO it is due to the Josephson medium weak-link effects. This result provides the evidence that in Bi compounds strong-current Josephson contacts are possible. The influence of high magnetic fields on the Josephson critical current is briefly discussed.

The effect of a strong magnetic field on the Josephson critical current Jc is considered. It is shown that if the Abrikosov vortex in the superconducting electrodes is rigidly pinned, the Jc value depends on the distribution of the vortex density and drops slowly with the increase in an external magnetic field. If the Abrikosov vortices within the electrodes are in a liquid phase there may be an exponentially rapid decrease in the magnitude of Jc with increase in the transverse field.

E-mail: Stepanovkapella.gpi.mYurii A.Shulagin,Institute of Oceanology of Russian Academy of ScienceMoscow, RussiaAlexander I.D'yachenkoInstitute ofBiomedical Problems, Moscow, RussiaABSTRACTMiddle infrared tunable diode lasers (TDL) were applied to studies of pulmonary excretion of endogenous carbonmonoxide (CO). Variations of the CO content level in exhaled air of healthy nonsmokers were investigated fordifferent environmental conditions with the applied laser technique. Correlation ofthe obtained data with atmosphericCO contamination and elevated oxygen content were studied as well as diurnal variations of the endogenous CO inexhalation was observed. Criteria for correct conditions ofthe endogenous CO detection in breath could be derived onthis basis. Developed laser approach and methods were applied for the analysis ofthe excreted CO level in differentdiseases like bronchial asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease,anemia and hepatitis. Laser based close-to-real-time monitoring ofthe endogenous CO elimination with breath in thecourse of different dynamic tests was demonstrated to be informative in studies of blood oxygen transport and pH

Improved tunneling spectroscopy was carried out on high-Tc BSCCO(2212) single crystal, and it provided us a reflection spectrum of the quasi-particle that mediates the strong Cooper pairing. The point contact junction enabled us to observe significant fine structure spectrum beyond the gap edge up to 0.2 eV. The spectrum peaks both in positive and negative bias ranges were found to be in a good one-to-one correspondence to the phonon density-of-states peaks at energy level $HBAR(omega) i reported by the neutron scattering experiment. The significant peaks at higher energies could be also assigned by n(epsilon) O + $HBAR(omega) i (n equals 0.1.2) where (epsilon) O is the breathing mode energy. Numerical computation in terms of the Eliashberg gap equation was carried out and the electron-phonon coupling intensity function (alpha) 2F((omega) ) was elucidated. Most of the peak modes were attributed to the optical phonons due to oxygen oscillations in and around the (CuO2)n plane, wherein the superconducting electronic state takes place. Consequently it turns out that the breathing mode has an essential role in the high-Tc superconductivity in the perovskite type-oxides.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An influence of anisotropy on phonon structure in d2I/dV2(V) curve was examined by direct solving of the Eliashberg equations. The studies include the s- and d-types of pairing symmetry as well as scattering on impurities. As is revealed the phonon structure in the second derivative remains isotropic and should be found at eV equals $HBAR(omega) plus where (omega) is the phonon frequency and the effective gap is close to the maximum value of (Delta) (k) in the case of strong anisotropy of energy gap (Delta) (k). The smearing of phonon structure could be taken into account by using a complex gap function (Delta) ((omega) +i(Gamma) ) in the Dynes' formula. The influence of the localized states on the phonon structure in d2I/dV2 is discussed.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Double cyclization of N-acetyl-2-(cyclopent-2-enyl)aniline initiated by ozonolysis resulted in 9-acetyl-2-hydroxy-2,3,4,4a,9,9a-hexahydropyrano[2,3-b]indole.

The results of investigation of the Josephson medium specific nature in metal ceramics make basis of this review. Equations permitting to describe the electrodynamics of networks of the superconductor-normal metal-superconductor type contacts have been obtained. Effect of pressure on a current transfer in the Josephson medium was analyzed and relationship between the critical current density and the width of resistive transition in ceramics was found. A theory has been developed for reconstructing the current-voltage characteristics of ceramics from magnetization measurements in pulsed magnetic fields.

Magnetic properties of superconductors with peak effect were investigated both experimentally and theoretically in frames of the critical state model which incorporates the flux jump instability criterion. Theoretical analyses show some “forbidden” band for flux jumps on the magnetic field axis. Features of H-T diagrams of instability of superconductors with peak effect are discussed.

The magnetic field - temperature ranges where the critical state for type II superconductors is unstable were calculated in terms of the following pinned critical state models: the Kim-Anderson model, the exponential model and the linear model. Comparative discussion of H-T diagrams of flux instabilities is presented.

An unusual direction of the reaction of 2-(cyclopent-2-enyl)aniline hydrochloride with dimethyldioxirane was found: the formation of two isomeric products,viz., 3- and 6-chloro-2-(cyclopent-2-enyl)anilines, was observed.

Tunneling conductance spectra were observed by point contact junction of SIN on single crystals of BSCCO (2212). Outside of the definite gap structure edge, significant fine structures were observed almost reproducibly ranging to 0.2 eV. The conductance derivative peaks both in positive and negative bias range were found in well one by one correspondence with the phonon spectrum peaks reported by Renker et al . [1]. Most of the peak modes were attributed to the optical phonons due to the oxygen oscillations in and around the [CuO 2 ] n net-plane. Numerical computation in terms of the Eliashberg gap equation was carried out, and the electron-phonon coupling intensity function α 2 F ( ω ) was elucidated and it turns out that the breathing mode relating to the polaronic valence fluctuations are predominant as compared with the B 1 g mode regarding the spin correlations.

A new model is developed todescribe the phsyics of a strong magnetic filed H influence on the high-T c metal ceramic critical current J c . The point is that in the most general case the J c (H) value is determined by the magnitude of a surface current j sf induced in the granules. The basic idea of the model is that the surface current density j sf is the sum of two components j sf =j m +j g . In the Meissner state j m is a diamagnetic (equilibrium) surface shielding current. In the mixed state j g is induced intragrain current whose sign depends on the magnetic history.

It was found that in YBaCuO textured MTG-ceramics RF (∼ 10 6 and ∼ 10 9 Hz) absorption is increased at reverse variation of the external static field. This result is contrary to the situation, observed in common metal ceramic samples, where RF absorption is decreased at decrease of the external field.

It was found that pressure has a strong influence on the critical current hysteresis loop of ceramics at H ∼ 10 kOe. The phenomenon is attributed to the critical current hysteresis of separate Josephson contacts and is due to the Abrikosov vortex density gradient within granules. The gradient defines both the sign and the value of the pinning current, whereas the sign of Meissner reversible surface current component is determined by the external field H direction. As a result the critical current of Josephson contacts defined by the total surface value depends on the magnetic prehistory of a sample.

The influence of the halogen on the strength of the adjacent C-Li bond has been evaluated on the basis of thermodynamic and quantum-chemical calculations, and it has been shown that monomolecular decomposition is preferable for LiCHCl2, LiCCl3, LiCF3, and o-FC6H4Li under the conditions of the experiment, while such decomposition is impossible for LiCH2Cl.

The literature data on the methods for the synthesis of unstable intermediate species (arynes and carbenes) from organoelement compounds, mainly from o- and ?-halogeno-derivatives, are surveyed and examined critically. It is shown that the ease of decomposition of the initial compound is determined by the possibility of the formation in the transition state of the coordinate bond between the groups or atoms eliminated and the theoretical proof of this mechanism is given. The bibliography includes 322 references.

1. Theoretical grounds have been given for a consistent single-stage mechanism for the decomposition of geminal and vicinal organometallic halogen compounds (OMHC) with the formation of carbenes and arynes, the driving force of which is intramolecular coordination of the halogen and metal atoms. 2. Within the framework of this mechanism, an analysis has been made on the manner in which OMHC stability depends on the heat effect of the decomposition reaction, the difference in energies of the coordinating orbitals, and the distance between the atoms that split out.

The effect of hydrostatic pressure (up to 12 kbar) on the phonon and electron characteristics of lead and lead-indium alloys have been studied in detail by electron tunnelling. Quantitative data on the change of the superconducting energy gap and the Van Hove Singularities for the phonon spectra were obtained. The energy dependence of the microscopic Gruneisen parameters was found for Pb–In alloys. We present consistent data on the pressure dependence of the electron–phonon interaction characteristics, particularly the function α2(ω)F(ω), the renormalization function Z N(ω), and the electronic characteristic parameter E. The experimental tunnelling density of states is in qualitative agreement with that calculated from the Eliashberg equations. This comparison confirms the accuracy of the basic equations for superconductivity under changes of volume. An analysis of the pressure dependence of the superconducting transition temperature T c is made on the basis of the exact and approximate expressio...

1. The formation of biphenylene in the decomposition of o-halophenyllithiums takes place with the intermediate participation of the corresponding 2-halo-2′-lithiobiphenyls, the cyclization of which into biphenylene is considerably accelerated by adsorption or by complex-formation with aromatic compounds. 2. On the basis of decomposition reactions of o-halophenyllithiums, a method has been developed for the synthesis of biphenylene with a yield of 50–60%.

The formation of methylenecyclobutane in the reaction of tetrahaloneopentanes and related compounds with zinc is shown to proceed via organozinc intermediates.

In [1], which is an expanded version of the paper [2], the equations of conservation of mass and momentum are shown to be valid for dynamical problems of lung parenchyma. This system of equations is now closed by means of the heat flux equation. As in [1, 2], the heat flux equation is obtained on the basis of the methods of the mechanics of heterogeneous media [3] and anatomical data on the structure of lung parenchyma.