Influence of Cyclodextrins on the Kinetics of Oxidation of Amino Acids and BSA by Hydrazyl Radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin.     

Fe NMR, magnetization and X-ray study of Cd0.1Cu0.9Fe2O4 ferrite

⁵⁷Fe NMR spin-echo spectra, static magnetization and X-ray diffraction measurements for Cd_0.1Cu_0.9Fe₂O₄ ferrite taken in a wide range of temperatures are presented. The X-ray studies show that above 100 K the structure is cubic. The temperature dependence of the effective magnetic field acting on ⁵⁷Fe nuclei at non-equivalent tetrahedral and octahedral sites has been determined. Different thermal behaviour of the magnetic field at both sublattices and of the specific macroscopic magnetization have been found. Magnetization measurements imply that cadmium substitution does not affect the ferric ion distribution between the sublattices of the ferrite.     

The microscopic investigation of structures of moving flux lines by neutron and muon techniques

We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low T _c type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbor FLL direction. This tends to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo technique to observe the energy change of neutrons diffracted by moving flux lines. The muon spin rotation (μSR) technique gives the distribution of values of magnetic field within the FLL. We have recently succeeded in performing μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors.     

Mössbauer effect and NMR studies of copper-cadmium ferrites

Hyperfine magnetic field distributions have been observed at room temperature in Cd _x Cu_1?x Fe₂O₄ (0≤x≤0.5) ferrites by the Mössbauer and NMR methods and are explained by statistical distributions of metallic ions separately within A and within B crystal sublattices.     

Direct observation of the Aharonov-Casher phase

Ring structures fabricated from HgTe/HgCdTe quantum wells have been used to study Aharonov-Bohm type conductance oscillations as a function of Rashba spin-orbit splitting strength. We observe nonmonotonic phase changes indicating that an additional phase factor modifies the electron wave function. We associate these observations with the Aharonov-Casher effect. This is confirmed by comparison with numerical calculations of the magnetoconductance for a multichannel ring structure within the Landauer-Büttiker formalism.     

Phase diagram of the spin Hall effect

We obtain analytic formulas for the frequency-dependent spin-Hall conductivity of a two-dimensional electron gas (2DEG) in the presence of impurities, linear spin-orbit Rashba interaction, and external magnetic field perpendicular to the 2DEG. We show how different mechanisms (skew scattering, side jump, and spin precession) can be brought in or out of focus by changing controllable parameters such as frequency, magnetic field, and temperature. We find, in particular, that the dc spin-Hall conductivity vanishes in the absence of a magnetic field, while a magnetic field restores the skew-scattering and side jump contributions proportionally to the ratio of magnetic and Rashba fields.     

Self-reported fatigue and health complaints of refuse collectors

Central European Journal of Operations Research - Working as a refuse collector is a physically strenuous activity. The aim of the investigations in this work was to evaluate the fatigue and...     

Combined17O/1H MRI study in a whole-body scanner

A simple method of obtaining consecutive¹H and natural-abundance¹⁷O images is described with a scanner’s original body resonator (for¹H) and a homemade linear birdcage (for¹⁷O). Two kinds of experiments were performed to test the method. In the first experiment, a proton image of the phantom was acquired with a whole-body resonator. In the second experiment, the phantom was inserted into an oxygen birdcage resonator and imaged again with a whole-body resonator. The intensities of images resulting from the experiments were analyzed. Although theB ₁ field homogeneity is disturbed, the proton images acquired with a whole-body resonator when the oxygen resonator is present are of acceptable quality for use in the combined¹⁷O/¹H imaging.