Possibility of Direct Observation of the Bloch—Siegert Shift in Coherent Dynamics of Multiphoton Raman Transitions

JETP Letters - Dust structures formed in exothermic chain plasma chemical processes initiated by pulsed gyrotron radiation in mixtures of metal and dielectric powders are studied. The composition...     

Bloch–Siegert shift in application to the astrophysical determination of the fundamental constants variation

We have evaluated the Bloch–Siegert shift for the different values of magnetic field?s strengths defined at astrophysical conditions, i.e. when the stars with the strong surface magnetic fields are taken as a powerful pumping source of radiation. It is found that the additional shift of resonant frequency should be taken into account in the search for the time variation of the fundamental constants. The main conclusion is that the influence of the electromagnetic field should be considered carefully in each special case of the corresponding frequency determination.     

19F NMR的特点

¹⁹F的磁旋比和相对灵敏度接近质子;¹⁹F NMR化学位移范围可达 δ 1 000,谱图分辨率高;¹⁹F NMR对环境因素较氢谱远为敏感、复杂,可反映出化合物结构的细微差别. 由于正常生物体内含氟成分很少,干扰小,因此在生物医学研究中引入氟代物进行¹⁹F NMR研究有特殊意义. 对氟化物的¹⁹F NMR化学位移和偶合常数的范围也分类作了总结.     

Temperature Dependencies of 19F NMR Spectra Parameters in BF4 − Solutions

Abstract

Despite numerous studies on the BF₄ ^? anion ^1-6 indicating to its complex behavior in different solutions in the presence of different cations, it is still quite difficult to explain this unambiguously. This is ostensibly due to the incompleteness of experimental data both for temperature dependencies and for solution compositions³. Taking this into account, we measured the dependencies of ¹⁹F NMR spectra in a broad range of temperatures and concentrations in aqueous and water-acetone solutions of Co²⁺, Ni²⁺ and Zn²⁺ tetrafluoroborate salts on “RYA-2305” and “SWL 2-31/10” instruments in spherical and cylindrical ampoules. The said dependencies were recorded both for BF₄ ^? and BF₃OH^? signals, the latter forming in insignificant quantities due to the hydrolysis of the tetrafluoroborate anion in positively hydrated cation solutions¹.     

Shift of the photoemission threshold in III–V and II–VI semiconductors

The reasons why the photoemission threshold energy of semiconductors is lower than the ionization energy of constituent atoms have been investigated. It has been indicated that the previously proposed interpretation of this phenomenon based on the inclusion of an additional intra-atomic Coulomb interaction between the valence electrons is insufficient. It has been shown that the calculation of the electronic energy structure of semiconductors, in particular, of the photoemission threshold, requires taking into account a change in the localization region of the valence electrons when a free atom is embedded into a crystal. A way of taking this change into account in the tight-binding theory has been demonstrated. Corrections to the tight-binding Hamiltonian have been found. The photoemission thresholds of III–V and II–VI semiconductors have been calculated with the inclusion of these corrections. Comparison of the results with the experimental data has been performed.     

NMR Studies of Drugs. Applications of Achiral and Chiral Lanthanide Shift Reagents to the Analgesic,Famprofazone: “Anomalous Shifts”

The 200 MHz ¹H NMR spectra of the analgesic, famprofazone, 1, have been studied in CDCl₃ solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptaf luoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu(FOD)₃, 2, for spectral simplification, and with the chiral LSR, tris [3-(heptafluoropropylhydroxymethylene) - (+) camphorato] europium (III), Eu (HFC)₃, 3. Lanthanide induced shift (LIS) magnitudes suggested predominant LSR binding at the carbonyl oxygen. Substantial enantiomeric shift differences were observed for several nuclei of 1 with added 3 which could permit direct determinations of enantiomeric excess.     

Applications of airborne ultrasound in human–computer interaction

Airborne ultrasound is a rapidly developing subfield within human–computer interaction (HCI). Touchless ultrasonic interfaces and pen tracking systems are part of recent trends in HCI and are gaining industry momentum. This paper aims to provide the background and overview necessary to understand the capabilities of ultrasound and its potential future in human–computer interaction. The latest developments on the ultrasound transducer side are presented, focusing on capacitive micro-machined ultrasonic transducers, or CMUTs. Their introduction is an important step toward providing real, low-cost multi-sensor array and beam-forming options. We also provide a unified mathematical framework for understanding and analyzing algorithms used for ultrasound detection and tracking for some of the most relevant applications.     

Applications of laser in the field of chemical solubility determination

A novel experiment method for chemical solubility determination was brought forward, in which optics and chemistry principles are united and the change of laser intensity indicates the process of chemical dissolving. The more undissolved solid exists in the mixture of solute and solvent, the less transmitted laser intensity is detected. Only when the transmitted laser intensity in stirring state and that in static state comes into equalization, the dissolving process stops. Under the help of laser intensity judgement, measurements turn to be more feasible and objective, especially at high pressure. The average relative errors for the solubility data determined in this paper are 2.3% for those in the minor value scope and 1.7% for those in the high value scope respectively. Comparison of the experimental solubility data with the literature ones demonstrates that the laser-aid solubility determination apparatus is stable and reliable.     

19F NMR技术在蛋白质研究中的应用

因为¹⁹F核自身的特性,如自旋为1/2;丰度高(100%),具有与¹H相当的灵敏度;化学位移分布广且对环境敏感;绝大部分生物体内都不含¹⁹F因而无背景干扰等;¹⁹F NMR自诞生以来就成为非常有吸引力的研究手段. 现在,¹⁹F NMR已被广泛用于核磁共振成像、药物化学及生物大分子的研究,各个方面均有较多的相关文献综述. 该综述将集中讨论¹⁹F NMR在蛋白质研究中的应用,包括蛋白质¹⁹F标记方法,¹⁹F NMR在蛋白质结构、 动力学、蛋白质折叠、蛋白质与药物的相互作用及In-cell NMR中的应用.     

Numerical solution of Bloch–Gruneisen function to determine the contribution of electron–phonon interaction in polycrystalline MgB2 superconductor

Here, we report the efficient and feasible analytical method for the generalized Bloch–Gruneisen law in association with Debye temperature and various temperatures range in terms of incomplete gamma function. In addition, our results are in agreement with previous reports as shown in this letter. Bloch–Gruneisen function describes the contribution of electron–phonon interaction to the results of temperature dependence behavior of resistivity for integer and noninteger values of index m. In conclusion, the algorithm is constructed in Fortran 90 language for replicate the variation of temperature dependence of resistivity for pristine MgB₂ sample. Moreover, the comparison of numerical results with the proposed method reveals the validity and precision of the method.     

Novel Heptamethine Cyanine Dyes with Large Stokes’ Shift for Biological Applications in the Near Infrared

A series of novel functionalized, water-soluble, pH-unsensitive, highly photostable heptamethine cyanine dyes (HCDs) has been synthesized. The aim of the synthesis was to obtain novel effective probes for fluorescence detection in the near infrared. Synthesis and characterization of a special HCD with large Stokes’ shift (>100 nm), bioconjugation to IgG and effect of pH upon the new structure are presented.     

Numerical Simulation of the Non-Fourier Heat Conduction in a Solid-State Laser Medium

A hyperbolic model of non-Fourier heat conduction with non-uniform heat source is used to simulate the transient heat transfer in a high-pulse-pumped solid-state laser medium. The temperature fields are numerically analysed using the finite difference method combined with the TDMA algorithm for different pump power densities, pulse durations, thermal relaxation time and cooling intensities, respectively. The calculated results are compared with those predicted by the parabolic heat conduction model based on the Fourier law. The results indicate that the non-Fourier heat conduction phenomenon in laser media should be considered when the pump power density exceeds 104 W/m^2 or under low pulse duration. In addition, the conditions of non-Fourier effects and their influencing factors are analysed.     

Solution of Gauss-Codazzi Equation with Applications in the Tzitzeica Equation

The surface in R3 associated with the Tzitzeica equation ＆ considered. By curvature coordinate transformation and surface imbedding, the Gauss-Codazzi equation is presented. Resorting to the solutions of the Gauss-Codazzi equation, the solution of the Tzitzeica equation ＆ obtained under a restrictive condition.     

18F production in the 19F(γ, n) reaction

A race-track microtron is used to measure the yield of ¹⁸F in the reaction ¹⁹F(γ, n) at an energy of the electron beam of 55 MeV. ¹⁸F is widely used in positron emission tomography for high-sensitivity diagnostics. The currently available data are not sufficient to make accurate estimates of the yield of ¹⁸F in isotope production experiments using the reaction (γ, n). The value of σ^?1 estimated in this work is (1.7 ± 0.1) mb.     

氟苯类化合物19F NMR化学位移的计算

提出了计算氟苯类化合物¹⁹F NMR化学位移的公式：δ_cal（¹⁹F）=-113.5+Δo+Δm+Δp+C, 结合最小二乘法通过线性回归得到了20种取代基参数, 计算结果以160种氟苯类化合物的263个¹⁹F NMR化学位移数据为样本点作回归检验,置信度为99.5%,计算值与实验值的平均偏差为0.628,计算值与实验值的标准偏差为4.720,约有93.2%的¹⁹F NMR化学位移计算值的计算误差<7.0（相对误差<0.7%）.     

Negative Goos–Hanchen Shift at the Interface of a Multisublattice Antiferrodielectric

Physics of the Solid State - The interaction of an electromagnetic radiation with electric dipole active spin modes in a multisublattice antiferrodielectric is shown to possibly lead to anomalous...     

Temperature Shift of the Zero-Phonon f–f Lines of Er3+ Luminescence in Quantum Paraelectric KTaO3

Physics of the Solid State - In KTaO3:Er crystals, we observed a temperature shift, unusual for rare earth impurities, for narrow zero-phonon luminescence lines, due to the 4S3/2 → 4I13/2,...     

Solutions of the Bethe–Salpeter Equation in Minkowski Space and Applications to Electromagnetic Form Factors

We present a new method for solving the two-body Bethe–Salpeter equation in Minkowski space. It is based on the Nakanishi integral representation of the Bethe–Salpeter amplitude and on subsequent projection of the equation on the light-front plane. The method is valid for any kernel given by the irreducible Feynman graphs and for systems of spinless particles or fermions. The Bethe–Salpeter amplitudes in Minkowski space are obtained. The electromagnetic form factors are computed and compared to the Euclidean results.