Dependence of nuclear quadrupole double resonance spectra on the level of the saturating radio-frequency field

The dependence of the intensity of nuclear quadrupole double resonance (NQDR) lines on the level of the saturating rf field and the nature of its absorption has been studied. It has been shown that the intensity of the solid-state doublets depends on the square of the amplitude of the saturating field. Pure solid-state doublets have been recorded for the first time for amino groups in eight compounds. Picolinamide, nicotinamide, acetamide, and trichloroacetamide comprise a group of compounds with similar values for the quadrupole coupling constants and the asymmetry parameters. Urosulfan, guanidine chloride, urea, and thiourea make up another group. The interproton distances in the amino groups have been determined in all the compounds on the basis of the multiplet structure of the NQDR lines.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 21, No. 2, pp. 237–240, March–April, 1985.We thank A. I. Stetsenko for supplying the compounds for the investigation.     

Effectiveness of NQR signal detection in noise in multiple-pulse sequences

A technique for signal processing in multiple-pulse experiments is examined. Results are obtained which permit selection of the NQR-signal parameters for its detection in a noise background and optimization of the signal processing parameters, in particular, minimization of the experiment time.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 46–50, January, 1989.     

Effects and Corrections for Mobile NMR Measurement

Nuclear magnetic resonance (NMR) under motion has drawn significant attention in recent years. Motion of the NMR probe has serious effects on NMR measurement. For example, NMR logging normally runs at downhole condition with tool motion at a speed of 30 ft/min. We propose here methods for motion corrections of NMR data based on the quantitative analysis of motion effects on polarization and echo acquisition. We also produced a multi-functional NMR scanning system to verify the theoretical analysis. Presented experiments demonstrate that the theoretical and experimental results match very well.     

Probing Structural Compositions of Porous Media with Two-dimensional Nuclear Magnetic Resonance

Combination of two-dimensional nuclear magnetic resonance (2-D NMR) correlation maps and a simple three-component model are proposed here to identify the structural composition of porous media. Homogeneous magnetic field and field with constant gradient of a novel Halbach sensor are employed for respective relaxation and diffusion measurements. NMR results are compared and confirmed with independent measurements on a scanning electron microscope and by energy dispersive spectrometer methods.     

Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Modeling of the stress state of the thumb carpometacarpal joint

The stress state of the carpometacarpal joint (CMJ)was studied in sound and pathologic states by methods of continuum mechanics. The CMJ geometric model was constructed according to the results of computer processing of the data of tomographic investigations in the extension position, which were obtained at Cheng Kung Medical University (Taiwan). The study of contact interactions in the CML region for a given geometry were performed numerically in the ABAQUS program code. The obtained numerical solutions of contact problems permit comparatively analyzing the stress distribution in the bone tissue for various thumb positions and study the stress state dependence on the bone tissue porosity (osteoporosis), which varies with human age.     

First spin flipping of a stored spin-1 polarized beam

We recently studied spin flipping of a 270 MeV vertically polarized deuteron beam stored in the Indiana University Cyclotron Facility Cooler Ring. We adiabatically swept an rf solenoid's frequency through an rf-induced spin resonance and observed its effect on the deuterons' vector and tensor polarizations. After optimizing the resonance crossing rate and maximizing the solenoid's voltage, we measured a vector spin-flip efficiency of 94.2%+/-0.3%. We also found striking behavior of the spin-1 tensor polarization.