核磁共振实验最佳信号的获得

通过分析各个实验参数对核磁共振信号的影响,提出并实现了最佳信号获得的方法。实验表明,对信号影响较大的因素主要有三个,即磁场强度、样品质量和扫描电压。而这三个参数中尤以磁场强度对信号的影响最为显著。     

The effect of 2.1 T static magnetic field on astrocyte viability and morphology

The viability and a number of morphological properties of in situ astrocytes of rat spinal cord cultures including changes in surface area and migration of both cell body and nucleus were investigated at magnetic field intensities comparable to those currently used for magnetic resonance imaging. Viability of rat spinal astrocytes was studied after up to 72 hours of 2.1T static magnetic field exposure. Surface areas and two-dimensional centroids of both soma and nucleus after 2 hours of magnetic field exposure were determined and compared with those of the same cells before magnetic field exposure. Cell membrane ruffling was quantified using fractal analysis.     

Numerical calculation of trapped magnetic field for square multiple bulk superconductors

In this work, the trapped magnetic field was calculated for square bulk superconductors using the sand-pile model and Biot–Savart law. The numerical simulation of the trapped magnetic field was performed varying the sample dimensions, distance between the sample surface and observation point. In addition the magnetic field characteristics of superconducting bulk arrangement in an array was determined. The trapped magnetic field was found to be depending on the sample dimensions and distance between the sample and observation point. It is observed that, when the distance from the surface is larger, the value of the trapped magnetic field decreases, but the variation of the trapped magnetic field becomes small due to averaging the distribution of the trapped magnetic field.     

A Comparative Study of Electron Heat Transport in a Stochastic and a Non‐Stochastic Magnetic Field

We studied the electron heat transport across a non‐local stochastic magnetic field and a non‐local non‐stochastic magnetic field in tokamak plasmas. Analytical results and numerical simulation results were compared with conditions of a stochastic and a non‐stochastic magnetic field respectively in this article. Parameter of stochasticity in perturbed magnetic field was found not tobe a key factor in influencing effective radial heat conductivity in radial direction of tokomak when Chirikov parameter is close to one (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The effect of temperature on laws of minor hysteresis loops in nickel single crystals with compressive deformation

The temperature dependence of minor hysteresis loops of compressively deformed nickel single crystals has been investigated in a wide temperature range below the Curie temperature of 628 K. There exist power-law relations between the field-dependent parameters of minor-loops, and their exponents are independent of both temperature and strain after the compressive deformation. These observations indicate the presence of universal power laws in minor hysteresis loops. The minor-loop coefficients of the power laws show a similar temperature dependence of the coercive force, which is quantitatively related to the dislocation density. These properties of minor hysteresis loops are useful for the accurate and quantitative nondestructive evaluation of age degradation in ferromagnetic materials.     

Reaktion von Pyridin-2-Carbonsäure Mit Tetrabutylammonium-Tetrachloro-Nitridotechnetat(VI) Sowie Tetrabutylammonium-Tetrachlorooxotechnetat (V)

Abstract

The reaction of 2-pyridine carboxylic acid (Hpic) with (n-Bu₄N)[TcNCl₄] and (n-Bu₄N)[TcOCl₄] in ethanol and methanol, respectively, yields the dinuclear μ-oxo complex [(pic)₂NTc-O-TcN(pic)(Hpic)Cl] and the monomeric complex [TcO(pic)₂Cl].

Visible and infrared spectroscopy, ESR, ¹H-NMR and ⁹⁹Tc-NMR have been used to characterize the new compounds. The most important field of application for the new compounds synthesized is radiodiagnostics.     

The effects of Zn vacancies on ferromagnetism in Cu-doped ZnO films controlled by oxygen pressure and Li doping

Zn0.99Cu0.01O films were studied experimentally and theoretically.The films were prepared by pulsed-laser deposi tion on Pt(111)/Ti/SiO2/Si substrates under various oxygen pressures to investigate the growth-dependence of the ferromag netic properties.The structural,magnetic,and optical properties were studied,and it was found that all the samples possess a typical wurtzite structure,and that the films exhibit room-temperature ferromagnetism.The sample deposited at 600℃and an oxygen pressure of 10 Pa showed a large saturation magnetization of 0.83μB/Cu.The enhanced ferromagnetism in the(Cu,Li)-codoped ZnO is attributable to the existence of Zn vacancies(VZn),as shown by first-principles calcu lations.The photoluminescence analysis demonstrated the existence of V Zn in both Zn0.99Cu0.01O and(Cu,Li)-codoped ZnO thin films,and this plays an important role in the increase of ferromagnetism,according to the results of first-principles calculations.     

Raman spectroscopy of very small Cd1−xCoxS quantum dots grown by a novel protocol: direct observation of acoustic‐optical phonon coupling

Glass‐embedded Cd_1−xCo_xS quantum dots (QDs) with mean radius of R ≈ 1.70 nm were successfully synthesized by a novel protocol on the basis of the melting‐nucleation synthesis route and herein investigated by several experimental techniques. Incorporation of Co²⁺ ions into the QD lattice was evidenced by X‐ray diffraction and magnetic force microscopy results. Optical absorption features with irregular spacing in the ligand field region confirmed that the majority of the incorporated Co²⁺ ions are under influence of a low‐symmetry crystal field located near to the Cd_1−xCo_xS QD surface. Electron paramagnetic resonance data confirmed the presence of Co²⁺ ions in a highly inhomogeneous crystal field environment identified at the interface between the hosting glass matrix (amorphous) and the crystalline QD. The acoustic‐optical phonon coupling in the Cd_1−xCo_xS QDs (x ≠ 0.000) was directly observed by Raman measurements, which have shown a high‐frequency shoulder of the longitudinal optical phonon peak. This effect is tuned by the size‐dependent sp‐d exchange interaction due to the magnetic doping, causing variations in the coupling between electrons and longitudinal optical phonon. Copyright © 2013 John Wiley & Sons, Ltd.