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141.
P. K. Gallagher 《Journal of Thermal Analysis and Calorimetry》1997,49(1):33-44
This brief tutorial and somewhat personal review discusses general experimental aspects and several examples of how thermomagnetometry has proven valuable in a variety of studies. The three areas of focus concern 1) determination of the magnetic transition temperature to characterize the material or to serve subsequently as a potential temperature standard for thermogravimetry; 2) detection of magnetic reactants, intermediates, or products during reactions and 3) following the reaction rates for such reactions. A broad range of materials is examined, metals, ceramics, catalysts, minerals, and inorganic complexes. 相似文献
142.
The cross section for the process BaCl(C2Π, ν = 0) + Ar → BaCl(C2Π, ν = 0, 1, 2) + Ar was measured by a laser induced fluorescence technique and found to be 16(7) Å2. This cross section is much larger than the intermultiplet energy transfer cross sections in the alkalis based on a comparison of the fine structure splitting. It is concluded that in the molecular case coupling of internal degrees of freedom plays an important role. 相似文献
143.
Kenji Uchimura Megumi Morimoto-Tomita Annette Bistrup Jessica Li Malcolm Lyon John Gallagher Zena Werb Steven D Rosen 《BMC biochemistry》2006,7(1):2-13
Background
Heparin/heparan sulfate (HS) proteoglycans are found in the extracellular matrix (ECM) and on the cell surface. A considerable body of evidence has established that heparin and heparan sulfate proteoglycans (HSPGs) interact with numerous protein ligands including fibroblast growth factors, vascular endothelial growth factor (VEGF), cytokines, and chemokines. These interactions are highly dependent upon the pattern of sulfation modifications within the glycosaminoglycan chains. We previously cloned a cDNA encoding a novel human endosulfatase, HSulf-2, which removes 6-O-sulfate groups on glucosamine from subregions of intact heparin. Here, we have employed both recombinant HSulf-2 and the native enzyme from conditioned medium of the MCF-7-breast carcinoma cell line. To determine whether HSulf-2 modulates the interactions between heparin-binding factors and heparin, we developed an ELISA, in which soluble factors were allowed to bind to immobilized heparin. 相似文献144.
M. Henini P. J. Rodgers P. A. Crump B. L. Gallagher G. Hill 《Journal of Crystal Growth》1995,150(1-4):451-454
We report on the molecular beam epitaxy growth of modulation-doped GaAs-(Ga,Al)As heterostructures on the (311)A GaAs surface using silicon as the acceptor. Two-dimensional hole gases (2DHGs) with low-temperature hole mobility exceeding 1.2×106 cm2 V−1 s−1 with carrier concentrations as low as 0.8×1011 cm−2 have been obtained. This hole mobility is the highest ever observed at such low densities by any growth technique. We also report the first observation of persistent photoconductivity in a 2DHG. An analysis of the number density and temperature dependence of the mobility leads us to conclude that the mobility is limited by phonon scattering above 4 K and interface scattering at lower temperatures. 相似文献
145.
Frankie P. Anderson John F. Gallagher Peter T. M. Kenny Clodagh Ryan David Savage 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):m13-m15
The title compounds, [Fe(C5H5)(C14H13O2)] and [Fe(C5H5)(C15H15O2)], respectively, contain the ferrocenyl η5(C5H4) and phenylene –C6H4– rings in a nearly coplanar arrangement, with interplanar angles of 6.88 (12) and 10.5 (2)°, respectively. Molecules of the ethyl ester form dimers through η5(C5H5)C—H⋯O=C hydrogen bonds, with graph set R(20), and, together with Csp3—H⋯π(C5H5) interactions, generate a one‐dimensional column (irregular ladder). Molecules of the isopropyl ester aggregate through η5(C5H5)C—H⋯π(C6H4) interactions. 相似文献
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147.
Addition of methyl phosphinate to 2(R)-methoxy 3-oxapentanedial gives all eight possible diastereoisomeric 3-phosphapentopyranoses in very poor yield. Structures and stereochemistry are assigned on the basis of 1H, 31P, NMR, and mass spectroscopy of their acetates. © 1996 John Wiley & Sons, Inc. 相似文献
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We show that silane pyrolysis is initiated by decomposition on the amorphous silicon surface, with an activation energy Ea of 56 kcal/mole. The observed surface decomposition rate is only weakly dependent on silane pressure. Much faster delayed decomposition rates, approximately independent of surface area and proportional to pressure, are shown to be initiated by surface reactons. A model for surface decomposition is given. Also a model for gas reactions is suggested based on H atom or SiH3 release by surface decomposition, causing chain reactions that process the gas to higher silanes that decompose rapidly. This model can explain the previous observations that the initial disilane formation rate and the delayed decomposition rate were independent of the surface area to volume ratio A/V, which had misled previous investigators to suggest homogeneous initiation processes. 相似文献