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Study of diffusion in erythrocyte suspension using internal magnetic field inhomogeneity 总被引:2,自引:1,他引:1
Lisitza NV Warren WS Song YQ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,187(1):146-154
Transport of water and ions through cell membranes plays an important role in cell metabolism. We demonstrate a novel technique to measure water transport dynamics using erythrocyte suspensions as an example. This technique takes advantage of inhomogeneous internal magnetic field created by the magnetic susceptibility contrast between the erythrocytes and plasma. The decay of longitudinal magnetization due to diffusion in this internal field reveals multi-exponential behavior, with one component corresponding to the diffusive exchange of water across erythrocyte membrane. The membrane permeability is obtained from the exchange time constant and is in good agreement with the literature values. As compared to the other methods, this technique does not require strong gradients of magnetic field or contrast agents and, potentially, can be applied in vivo. 相似文献
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Sangdoo Ahn Natalia Lisitza Warren S. Warren 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,133(2):266-272
Intermolecular zero-quantum coherences (iZQC) induced by the dipolar demagnetizing field can give bothP- andN-type cross peaks. This paper shows that the relative intensities of the two types of iZQC peaks follow a simple relation, tan2(θ/2), from both the quantum (spin density matrix) and classical (modified Bloch equation) calculations. The experimental data and numerical simulations agree well with the prediction. In addition, higher-order iZQCs are experimentally examined for the first time and are explained by the quantum picture in which dipolar couplings convert four-spin operators into observable magnetization. 相似文献
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Porous texture characteristics of a homologous series of base-catalyzed silica aerogels 总被引:2,自引:0,他引:2
Andrzej B. Jar
bski Jaros
aw Lorenc Yuri I. Aristov Natalia Lisitza 《Journal of Non》1995,190(3):198-205
Eighteen samples of base-catalyzed silica aerogels obtained using various tetraethylorthosilicate (TEOS) and water contents in the reaction system were characterized using N2 adsorption. From the observed pore size distribution and adsorption isotherms the volumetric and surface fractal dimensions were determined and also the range of power-law behaviour of the porous network. The porous texture of both the bulk aerogel and surface of clusters appeared to be dependent on the concentration of reactants. The water content, however, emerges as a factor controlling surface fractal structure, its principal effect being exerted on the pore volume in the mesopore size range. 相似文献
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Ryabova S. Yu. Alekseeva L. M. Lisitza E. A. Shashkov A. S. Chernyshev V. V. Tichomirova G. B. Goyzman M. S. Granik V. G. 《Russian Chemical Bulletin》2001,50(8):1449-1456
The possibility of transformation of 3-cyano-1-p-nitrophenyl--carbolin-2-one into 2-amino-3-cyano-1-p-nitrophenyl-1H-pyrido[3,2-b]indole derivatives and 2-imino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indole derivatives (-carbolines) is demonstrated. Methylation of 1-p-nitrophenyl-2-piperidino-1H--carboline followed by treatment with acetone in an alkaline medium yields 4-acetonyl-5-methyl-1,4-dihydro-5H-pyrido[3,2-b]indole derivative. The rearrangement of 2-arylimino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indoles into 2-(aryl)nitrophenylamino-3-cyano-5H-pyrido[3,2-b]indoles was accomplished on heating above the melting point or on treatment with potassium tert-butoxide. The structures of the resulting compounds were proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. 相似文献
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Measurements of water-proton spin-lattice relaxation rate constants as a function of magnetic field strength [magnetic relaxation dispersion (MRD)] in aqueous solutions of paramagnetic solutes reveal a peak in the MRD profile. These previously unobserved peaks require that the time correlation functions describing the water-proton-electron dipolar coupling have a periodic contribution. In aqueous solutions of iron(III) ion the peak corresponds to a frequency of 8.7 cm-1, which the authors ascribe to the motion of water participating in the second coordination sphere of the triply charged solute ion. Similar peaks of weaker intensity in the same time range are observed for aqueous solutions of chromium(III) chloride as well as for ion pairs formed by ammonium ion with trioxalatochromate(III) ion. The widths of the dispersion peaks are consistent with a lifetime for the periodic motion in the range of 5 ps or longer. 相似文献
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