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121.
122.
Experimental results on the nuclear spin-lattice and nuclear spin-spin relaxation times in the ferromagnetic EuB6 at temperatures below 4·2 K are presented using the external magnetic field,H
ext, in the range of 0 ⩽H
ext ⩽ 10 kG. Nuclear spin-spin relaxation time computed on the basis of the Suhl-Nakamura process turns out to be 3·2μs, which compares well with the experimental value 11·1μs obtained with the 10 kG magnetic field at 1·7 K. It is found that in the ferromagnetic EuB6,T
1 is approximately 5 × 103 times larger thanT
2 at 1·7 K with the 10 kG magnetic field. Thus the effect ofT
1 onT
2 can be neglected. From the experimental value ofT
2, the value of the homogeneous line broadening is found to be 14 kHz. The corresponding value obtained from the cw method
is 175 kHz. This evidently shows the presence of the inhomogeneous line broadening in the cw NMR. 相似文献
123.
124.
Harding LP Jeffery JC Riis-Johannessen T Rice CR Zeng Z 《Chemical communications (Cambridge, England)》2004,(6):654-655
Self-assembly of the ligand L(1) with Co(2+) into a dinuclear triple helicate [Co(2)(L(1))(3)](4+) produces an anion binding pocket which encapsulates perchlorate anions. Furthermore we demonstrate how this ability to bind anions can control ligand self-recognition properties. 相似文献
125.
Bluck LJ Jones KS Thomas J Liggins J Harding M Bingham SA Coward WA 《Rapid communications in mass spectrometry : RCM》2002,16(24):2249-2254
We have investigated a novel application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for the quantitative analysis of the isoflavones in food matrices. Previous methods have been hampered by the lack of analytical standards to introduce early enough in the extraction procedure to allow compensations for losses at all stages of the procedure. In this work we have produced standard materials that can be added at the initial extraction, by intrinsically labelling soya plants by growing them in an atmosphere enriched in the stable isotope of carbon in CO(2). On analysis these plants were shown to contain phytoestrogens at a high (up to 20%) level of enrichment. The dried plant material has been used to estimate the isoflavone concentrations of a set of spiked flours. For daidzein the methodology was shown to produce results comparable to those achieved by GC/MS techniques. The method was less successful for genistein, possibly due to the greater fragility of this compound under the conditions required for the analysis. 相似文献
126.
The new ergostane steroid ergosta-5,24(24')-diene-3beta,4beta,22R-triol (1), a pregnane, (E)-volkendusin, characterised as the diacetate (3), cycloartanes 4-6 and protolimonoids 7-9 were obtained from the leaves and twigs of Trichilia reticulata. 相似文献
127.
J. H. Harding 《辐射效应与固体损伤》2013,168(1):257-262
Abstract Methods are available which calculate the free energies of defects in ionic systems within the quasi-harmonic approximation. The Harwell SHEOL code is used to calculate the defect enthaplies and entropies for a number of alkali halides where reliable diffusion data are known. We discuss the trends in the calculations and the comparison with experiment. 相似文献
128.
John Harding 《Algebra Universalis》2012,68(3-4):193-196
Wilce introduced the notion of a topological orthomodular poset and proved any compact topological orthomodular poset whose underlying orthomodular poset is a Boolean algebra is a topological Boolean algebra in the usual sense. Wilce asked whether the compactness assumption was necessary for this result. We provide an example to show the compactness assumption is necessary. 相似文献
129.
A recently developed technique that shows great promise for studying the structural response of rotating objects is that of image-derotated holographic interferometry. The technique consists of optically subtracting the rotational motion of a disk by passing the image of the rotating disk through a prism that is rotating at half the disk's angular velocity. Heretofore, a pulsed ruby laser had to be used to record the rotating object's out-of-plane modes of vibration. This study reports on the extension of the technique to the real-time analysis of rotating objects by replacing the pulsed ruby laser with an acousto-optically modulated argon laser. Using the strobed argon laser in conjunction with the optical derotator, the rotating disk's normal displacement can be observed as it is being excited in real-time. This technique offers the distinct advantage of being able to observe the rotating disk's structural response over a wide range of pulse frequencies at any point in the disk's cycle of revolution. 相似文献
130.
It is well known that the category KHaus of compact Hausdorff spaces is dually equivalent to the category KRFrm of compact regular frames. By de Vries duality, KHaus is also dually equivalent to the category DeV of de Vries algebras, and so DeV is equivalent to KRFrm, where the latter equivalence can be described constructively through Booleanization. Our purpose here is to lift this circle of equivalences and dual equivalences to the setting of stably compact spaces. The dual equivalence of KHaus and KRFrm has a well-known generalization to a dual equivalence of the categories StKSp of stably compact spaces and StKFrm of stably compact frames. Here we give a common generalization of de Vries algebras and stably compact frames we call proximity frames. For the category PrFrm of proximity frames we introduce the notion of regularization that extends that of Booleanization. This yields the category RPrFrm of regular proximity frames. We show there are equivalences and dual equivalences among PrFrm, its subcategories StKFrm and RPrFrm, and StKSp. Restricting to the compact Hausdorff setting, the equivalences and dual equivalences among StKFrm, RPrFrm, and StKSp yield the known ones among KRFrm, DeV, and KHaus. The restriction of PrFrm to this setting provides a new category StrInc whose objects are frames with strong inclusions and whose morphisms and composition are generalizations of those in DeV. Both KRFrm and DeV are subcategories of StrInc that are equivalent to StrInc. For a compact Hausdorff space X, the category StrInc not only contains both the frame of open sets of X and the de Vries algebra of regular open sets of X, these two objects are isomorphic in StrInc, with the second being the regularization of the first. The restrictions of these categories are considered also in the setting of spectral spaces, Stone spaces, and extremally disconnected spaces. 相似文献