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111.
Quantitative and qualitative assessment of articular cartilage in the goat knee with magnetization transfer imaging 总被引:7,自引:0,他引:7
Didier Laurent James Wasvary Jianyun Yin Markus Rudin Theodore C. Pellas Elizabeth OByrne 《Magnetic resonance imaging》2001,19(10):377-1286
We investigated the role of collagen in the magnetization transfer (MT) effect in contrast to other macromolecules. By means of phantoms made of collagen, chondroitin sulfate (CS) and albumin, MR parameters have been optimized in order to reduce the acquisition time and improve the sensitivity, as well as to minimize the contributions from CS and albumin to the MT induced signal attenuation. The same method was used to study cartilage ex vivo (bovine articular and nasal cartilage plugs) and in vivo (goat knee femoral chondyle). In phantom samples, the MT signal attenuation depended on the collagen concentration while contributions from the other macromolecules were found to be minimal. In average, analysis of MT images revealed a 25%, 35% and 30% signal attenuation in 10% w/v type I collagen gels, cartilage plugs, and cartilage from the weight-bearing areas of the goat knee, respectively. Biochemical data revealed that treatment of cartilage plugs with bacterial collagenase led to collagen depletion and correspondingly to a decrease of the MT response. In contrast, trypsin-induced proteoglycan loss in cartilage plugs did not alter the MT effect. A significant correlation was observed between the collagen content in these plugs and their respective MT ratios and the rate constant k for the exchange process bound versus free water. Finally, data obtained from in vivo MT measurement of the goat knee demonstrated that intra-articular injection of papain might not only cause degradation of proteoglycans but also a change in collagen integrity in a dose-dependent manner. We conclude that in vivo measurement of MT ratios gives quantitative and qualitative information on the collagen status and may be applied for the routine evaluation of normal and abnormal articular cartilage. 相似文献
112.
F. de Oliveira Santos P. Himpe M. Lewitowicz I. Stefan N. Smirnova N. L. Achouri J. C. Angélique C. Angulo L. Axelsson D. Baiborodin F. Becker M. Bellegui E. Berthoumieux B. Blank C. Borcea A. Cassimi J. M. Daugas G. de France F. Dembinski C. E. Demonchy Z. Dlouhy P. Dolégiéviez C. Donzaud G. Georgiev L. Giot S. Grévy D. Guillemaud Mueller V. Lapoux E. Liénard M. J. Lopez Jimenez K. Markenroth I. Matea W. Mittig F. Negoita G. Neyens N. Orr F. Pougheon P. Roussel Chomaz M. G. Saint Laurent F. Sarazin H. Savajols M. Sawicka O. Sorlin M. Stanoiu C. Stodel G. Thiamova D. Verney A. C. C. Villari 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):237-247
The excitation function for the elastic-scattering reaction p( 18Ne, p) 18Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus 19Na. In addition, two-proton emission events have been identified and are discussed. 相似文献
113.
Smith JG Alexander JP Baker R Bebek C Berger BE Berkelman K Blanc F Boisvert V Cassel DG Dickson M Drell PS Ecklund KM Ehrlich R Foland AD Gaidarev P Gibbons L Gittelman B Gray SW Hartill DL Heltsley BK Hopman PI Jones CD Kreinick DL Lohner M Magerkurth A Meyer TO 《Physical review letters》2000,84(7):1393-1397
We present the first observation of the decay B-->J/psistraight phiK. Using 9.6x10(6) B&Bmacr; meson pairs collected with the CLEO detector, we have observed ten fully reconstructed B-->J/psistraight phiK candidates, whereas the estimated background is 0.5+/-0.2 event. We obtain a branching fraction of B(B-->J/psistraight phiK) = (8. 8(+3.5)(-3.0)[stat]+/-1.3[syst])x10(-5). This is the first observed B meson decay requiring the creation of an additional s&smacr; quark pair. 相似文献
114.
Beverly K Berger 《Annals of Physics》1974,83(2):458-490
Quantization in the spatially inhomogeneous, anisotropic, Gowdy three-torus solution of Einstein's equations leads to the production of gravitons from empty space. The creation of pairs of gravitons occurs only in wave modes with wavelength exceeding the horizon size at an initial time. The final number of created gravitons in any mode is proportional to the number of causally unconnected regions at the initial time over the wavelength of that mode. At large times, graviton number is well defined since the solution is in WKB form. The creation process produces the anisotropic collisionless radiation identical to that discussed by Doroshkevich, Zel'dovich, and Novikov which characterizes the large time classical solution. Near the singularity, the model behaves like an empty Bianchi Type I universe at each point in space (local Kasner). The canonical methods of Arnowitt, Deser, and Misner yield a reduced Hamiltonian from which the classical equations of motion are obtained. The quantization of the rapidly varying gravitational field component resembles the procedures used by Parker or Zel'dovich et al. to study particle creation in curved spacetime. 相似文献
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118.
The lattice constants of the compound Ca2NaK(PO4)2 have been studied at room temperature using an X-ray powder diffractometer and also in the temperature range from 20 up to 1000 °C by Guinier-Lenné-technology. A hexagonal lattice with the parameters a0 = 5.4367 Å and c0 = 7.3125 Å and a cell volume of 187.18 Å3 has been determined for the high temperature phase, existing from 670 °C upward. At temperatures below 670 °C a superlattice structure is formed by tripling the axis a, a ′, and c so that it results in a hexagonal superlattice structure cell with the lattice constants of a0 = 16.311 Å and c0 = 21.939 Å and a cell volume of 5054 Å3. 相似文献
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120.
The infrared absorption of the ν3 band region of SF6, at temperatures spanning the 130 to 297 K range, has been reexamined using improved instrumentation with one goal: to estimate the broadening of parameters by nitrogen gas. These parameters are compared to previous literature predictions and an extended set of IR cross-sections is proposed and compared to other existing datasets. 相似文献