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101.
Groups of structurally related materials, including the alkali halides, exhibit a proportionality of isothermal compressibility to formula-unit volume. The relationship has recently been explored by Glasser and by Recio et al. In this paper, we present the consequences of such proportionality on the relationships of Born-Lande? and Born-Mayer parameters to the formula-unit volume. These relationships have then been tested separately on (i) alkali (excluding cesium) halides and (ii) cesium halides. We conclude that the equations fit the NaCl-type materials satisfactorily, but less well for the CsCl-type materials, and that the Born-Mayer equation is more applicable. These results confirm the conclusion that volume is intimately linked to thermodynamic quantities, as already demonstrated by our development of volume-based thermodynamics (VBT). 相似文献
102.
In order to better understand the metabolic fate of n-3 polyunsaturated fatty acids (PUFAs), an efficient access to symmetrical and unsymmetrical triacylglycerols (TGs), esterified with PUFAs, with known high purity, is required. In this context, we optimized the esterification of a mixture of glycerols protected as dioxane and dioxolane with PUFAs. The kinetics of this reaction depends on various factors, such as the fatty acid chain length and the stereochemistry of the dioxane. Then, one-pot acetal hydrolysis and esterification of hydroxyl groups led to the desired structured TGs without either double bond isomerization or acyl migration (except when symmetrical TGs are acylated with long-chain saturated fatty acids in external positions). PUFAs location on the glycerol backbone was assayed by NMR, HPLC and pancreatic lipase hydrolysis. 相似文献
103.
An acoustic pointing task was used to measure extents of laterality produced by ongoing interaural temporal disparities (ITDs) conveyed by the envelopes of 4-kHz-centered raised-sine stimuli while varying, parametrically, their peakedness, depth of modulation, and frequency of modulation. One purpose of the study was to determine whether such manipulations would produce changes in laterality logically consistent with those found for ITD-discrimination thresholds reported by Bernstein and Trahiotis [J. Acoust. Soc. Am. 125, 3234-3242 (2009)]. The data obtained revealed that they did in that (1) increasing depth of modulation, peakedness, or frequency of modulation between 32 and 128 Hz produced smaller threshold ITDs and greater laterality and (2) increasing frequency of modulation to 256 Hz produced modest increases in threshold ITDs and modest decreases in laterality. The extents of laterality measured were successfully accounted for via an augmentation of the cross-correlation-based "position-variable" modeling approach developed by Stern and Shear [J. Acoust. Soc. Am. 100, 2278-2288 (1996)] to account for ITD-based extents of laterality obtained at low spectral frequencies. 相似文献
104.
M. Gadella M. L. Glasser L. M. Nieto 《International Journal of Theoretical Physics》2011,50(7):2144-2152
We study a one-dimensional singular potential plus two types of regular interactions: constant electric field and harmonic
oscillator. In order to search for the bound state energies, we shall use the Lippman-Schwinger Green function technique.
Another direct method will be mentioned for the harmonic oscillator. In the electric field case the unique bound state coincides
with that found in an earlier study as the field is switched off. For non-zero field the ground state is shifted and positive
energy “quasibound states” appear. The harmonic oscillator demonstrates the general result that for a symmetric potential
the odd states are not altered whereas the even states energies are lowered or raised accordingly as the delta perturbation
is attractive or repulsive. No states are created or annihilated. 相似文献
105.
Lameiras P Boudesocque L Mouloungui Z Renault JH Wieruszeski JM Lippens G Nuzillard JM 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(1):161-168
NMR of weakly polar analytes in an apolar ultraviscous solvent has recently been proposed for mixture analysis as a pertinent alternative to the DOSY experiment. The present article reports the first use of glycerol and glycerol carbonate as polar solvents for the NMR analysis of a model mixture of dipeptides. This work demonstrates the high potentiality of these solvents for the analysis of mixtures made of polar and potentially bioactive compounds. Medium-sized molecules slowly reorient in glycerol and glycerol carbonate under particular temperature conditions, so that solute resonances may show spin diffusion in NOESY spectra, thus opening the way to mixture analysis. Glycerol and glycerol carbonate have turned out to be ultraviscous solvents of choice for the individualization of four structurally close mixed dipeptides: Leu-Val, Leu-Tyr, Gly-Tyr and Ala-Tyr by means of 1D and 2D NOESY experiments. Selective sample excitation and signal detection were implemented to eliminate the intense proton signals of the non-deuterated solvents. Moreover, the recording of a multiplet selective 2D NOESY-TOCSY has shown that the analytical power of NMR in highly viscous solvents is not limited to the extraction of mixture component 1D subspectra but may also yield some supplementary information about atom connectivity within components. 相似文献
106.
This work reports the structure and superconducting properties of the superconductor ZrRuP doped with Fe; the ZrRu1−xFexP solid solution was investigated by means of X-ray powder diffraction, SQUID magnetometry and Mößbauer spectroscopy. It is shown that the modification of the superconducting properties by doping with Fe is similar to the effect of chemical pressure and that the Fe doped compounds do not show any magnetic ordering. 相似文献
107.
By varying the absorption coefficient and width of an intralipid-India ink solution in a quasi-one-dimensional experiment, we investigate the transition between the ballistic and the diffusive regimes. The medium's attenuation coefficient changes abruptly between two different values within a single mean free path. This problem is analyzed both experimentally and theoretically, and it is demonstrated that the transition location depends on the scattering coefficient as well as on the measuring solid angle. 相似文献
108.
In a previous paper the authors, together with Balwant Singh, introduced an elementwisc characterization of weak subintegrality for an extension A?B of commutative rings. In the present paper we improve our methods for working with this characterization. This leads us to propose two new types of “elementary weakly subintegral extension”. 相似文献
109.
Leslie Au Byungkwon Lim Dr. Peter Colletti Young‐Shin Jun Prof. Younan Xia Prof. 《化学:亚洲杂志》2010,5(1):123-129
Gold microplates were synthesized in aqueous solutions by reducing HAuCl4 with the hydroxyl groups in both serine and threonine of bovine serum albumin (BSA), which is a globular protein in its native state. In this article, we systematically investigated the effects of temperature, pH value, the concentration of BSA, and ionic species on the reduction kinetics and thus the size and morphology of the final product. The optimal experimental conditions for producing uniform Au microplates include the following: an elevated temperature in the range of 55–65 °C, an acidic solution with pH≈3, and the presence of NaCl (0.14 M ). We found that if any one of these parameters was deviated from the optimal condition, Au microplates would not be formed in high yields. We also found that the surfaces of the as‐synthesized Au microplates were covered by a dense array of BSA bumps. 相似文献
110.
AbstractInteractions of glucopyranose, fructopyranose and sucrose with a proteinaceous receptor model have been examined to validate the stereomolecular mechanisms of sweet taste proposed for sugars. The methylene groups at C-6 of glucose, at C-1 and C-6 of fructose and at C-6, C-1' and C-6' of sucrose appear to play an important role as dispersive interaction centres with the receptor. 相似文献