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121.
Villaescusa LA Lightfoot P Teat SJ Morris RE 《Journal of the American Chemical Society》2001,123(23):5453-5459
Variable-temperature single-crystal X-ray diffraction using a synchrotron X-ray source has allowed the mechanism of negative thermal expansion in the pure silica zeolite IFR to be studied in greater detail than was previously possible over the temperature range 30-557 K. The results have allowed the changes in average atomic position with temperature to be measured and the structural features that are important in negative thermal expansion to be identified. The structure of zeolite IFR can be split into two regions: columns of fused rings that expand with temperature and the intercolumn regions, which tend to contract on heating. These competing changes combine to produce a material that contracts parallel to the crystallographic a and b axes and expands in the c-direction. Correlations between zeolite structure and thermal expansivity are also reported. 相似文献
122.
Abdur-Rashid K Faatz M Lough AJ Morris RH 《Journal of the American Chemical Society》2001,123(30):7473-7474
123.
The role of magnesium in the susceptibility of soldiers to noise-induced hearing loss 总被引:1,自引:0,他引:1
Walden BE Henselman LW Morris ER 《The Journal of the Acoustical Society of America》2000,108(1):453-456
A number of studies have demonstrated that magnesium, administered prophylactically, can reduce the amount of hearing loss resulting from noise exposure. This study explored the possible role of naturally occurring body magnesium concentration in susceptibility of soldiers to noise-induced hearing loss. Participants were 68 adult males who had received extensive noise exposure over several years as a result of training with weapon systems. Each participant provided a pure-tone audiogram, blood sample, and noise-exposure history. A variety of pure-tone indices was correlated with serum magnesium levels as determined by atomic absorption spectroscopy. No significant correlations were observed between any audiometric index and body magnesium. The results of this study, therefore, do not support the hypothesis that there is a strong association between naturally occurring body magnesium and susceptibility to noise-induced hearing loss. 相似文献
124.
Conditions for bromination at the C3 and C5 positions of a 1,4-dihydropyridine (DHP) were investigated. The effect of base concentration, base type, reaction temperature, and solvent were examined. DHP derivatives with ester and amide moieties were synthesized and brominated. The bromine atoms can be replaced by other substituents, utilizing Suzuki cross coupling. 相似文献
125.
126.
Germán A. Enciso Morris W. Hirsch Hal L. Smith 《Journal of Dynamics and Differential Equations》2008,20(1):115-132
Classical results in the theory of monotone semiflows give sufficient conditions for the generic solution to converge toward
an equilibrium or toward the set of equilibria (quasiconvergence). In this paper, we provide new formulations of these results
in terms of the measure-theoretic notion of prevalence, developed in Christensen (Israel J. Math., 13, 255–260, 1972) and Hunt et al. (Bull. Am. Math. Soc., 27, 217–238, 1992). For monotone reaction–diffusion systems with Neumann boundary conditions on convex domains, we show the
prevalence of the set of continuous initial conditions corresponding to solutions that converge to a spatially homogeneous
equilibrium. We also extend a previous generic convergence result to allow its use on Sobolev spaces. Careful attention is
given to the measurability of the various sets involved. 相似文献
127.
H R Morris A Chatterjee M Panico B N Green M A Almeida da Silva B S Hartley 《Rapid communications in mass spectrometry : RCM》1989,3(4):110-116
Two-sector linked-scan analysis of an unpurified proteolytic digest of a pyruvate decarboxylase enzyme (60,000 Da) has allowed the discovery and assignment of an amino-terminal post-translational modification and processing event. A difference in amino acid sequence from that predicted by a recently published nucleotide sequence has also been found. These results illustrate both the use and considerable potential of linked-scan methods for the analysis of complex biopolymer mixtures. 相似文献
128.
Moisture removal from a two-layer porous media in which air is circulated through one layer and moisture is removed from the second has not been well studied due to the emphasis given to single-layer systems. This two-layer configuration is common in natural and engineered systems and can be used as a means to create a barrier to downward migrating fluids and to remove liquids and gases that may be present in the finer layer. However, there is little data on moisture removal from a two-layer porous media in which air is circulated through one layer parallel to the interface and moisture is removed from the finer second layer by evaporation. A conceptual model of the moisture removal from a two-layer porous media system was developed and compared to experimental moisture removal rates from laboratory scale dry barriers. The limited experimental data agrees well with the results predicted by the conceptual model, providing an initial validation. 相似文献
129.
130.
Water plays an important role in ionothermal synthesis and it has been suggested that it can influence phase selection. We have carried out an extensive study to determine the phases produced at various ratios of water to ionic liquid in the microwave assisted ionothermal synthesis of fluorinated aluminium phosphate frameworks using 1-ethyl-3-methylimidazolium bromide and 1-ethylpyridinium bromide. Aluminophosphate chabazite is the main product under ionothermal conditions while at increased levels of water the ionic liquids appear to be poor templates with dense phases predominating. The low synthesis pressure in ionothermal reactions is demonstrated and the role of template breakdown in phase selection is also discussed. 相似文献