[en] Short communication

No abstract available

[en] Nuclear spin polarization of the residual ion formed from an alkali atom after its resonant two-photon two-ligth beam ionization via hyperfine structure energy states is calculated ein second-order time-dependent perturbation approach fr atomlight interaction and taking itno account all photoionization channels permitted inthe electric-dipole appoxiamtion. (orig.)

[en] We prospectively evaluated the feasibility and technical features of MR-guided lumbosacral injection procedures in open high-field MRI at 1.0 T. In a CuSO₄.5H₂O phantom and five human cadaveric spines, fluoroscopy sequences (proton-density-weighted turbo spin-echo (PDw TSE), T1w TSE, T2w TSE; balanced steady-state free precession (bSSFP), T1w gradient echo (GE), T2w GE) were evaluated using two MRI-compatible 20-G Chiba-type needles. Artefacts were analysed by varying needle orientation to B₀, frequency-encoding direction and slice orientation. Image quality was described using the contrast-to-noise ratio (CNR). Subsequently, a total of 183 MR-guided nerve root (107), facet (53) and sacroiliac joint (23) injections were performed in 53 patients. In vitro, PDw TSE sequence yielded the best needle-tissue contrasts (CNR = 45, 18, 15, 9, and 8 for needle vs. fat, muscle, root, bone and sclerosis, respectively) and optimal artefact sizes (width and tip shift less than 5 mm). In vivo, PDw TSE sequence was sufficient in all cases. The acquisition time of 2 s facilitated near-real-time MRI guidance. Drug delivery was technically successful in 100% (107/107), 87% (46/53) and 87% (20/23) of nerve root, facet and sacroiliac joint injections, respectively. No major complications occurred. The mean procedure time was 29 min (range 19-67 min). MR-guided spinal injections in open high-field MRI are feasible and accurate using fast TSE sequence designs. (orig.)

[en] Crystal orientation in a polycrystalline material determines the characteristics of the material. When a material is deformed, a specific crystallographic orientation of the grains with respect to the deformation direction becomes predominant. A technique used to determine crystal orientation or texture is the construction of a pole figure. A pole figure is a contour map, in stereographic projection, of the concentration of poles of selected crystallographic planes as a function of spatial orientation. The data used to produce pole figures are obtained by X-ray diffraction techniques. The techniques are complicated and can be simplified using computerized data acquisition, reduction, and CRT display techniques. Pole figures of cold-rolled cartridge brass (70Cu--30Zn) taken from published literature were found to closely compare with results achieved at Bendix Kansas City

[en] Nuclear spin maser based on a new masing mechanism is proposed, which is applicable to high-precision measurements of the electric dipole moment of neutron. To test this idea, a spin maser with a spin-polarized ¹²⁹Xe gas as a working substance was constructed. After a detailed investigation of the spin maser operation in an ordinary spin-masing mechanism, we introduced an additional component in the feedback loop of the maser in order to implement the proposed masing mechanism. A self-sustained oscillation of transverse spins has been observed which clearly indicates a realization of spin masing arising from the new masing mechanism. (author)

No abstract available

[en] The theory of preferred orientation determination (crystallographic- or spintexture) by Moessbauer effect is presented for the case of unpolarized and polarized source radiation. The maximum information one can get out from Moessbauer measurements for the case of dipole radiation (M1) are nine expansion coefficients of the texture distribution expanded in a series of spherical harmonics. These coefficients can be obtained by a fitting procedure of the experimentally determined line intensity ratios in an absoption spectrum with rotated source and absorber. The general theory is applied for M1 radiation (Fe⁵⁷) and the cases of pure Zeeman or quadrupole splitting of source and absorber. Extension to higher multipole radiation can be easily done. Some graphs of possible textures are shown. (orig.)

No abstract available

[en] The recent interest in using polarized fuels in controlled fusion is reviewed. The salient consequences of spin polarized fusion are the possibility of increased reactivity and control of the direction of the fusion products. Possible depolarization mechanisms in plasma devices are examined and shown to be small compared to the fusion burn rate. The several possible techniques for development of large polarized sources capable of producing polarized atoms at a rate greater than 10²⁰ sec^-1 are examined. (author)