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41.
Quasi-elastic Neutron Scattering combined with Molecular Dynamics simulations have been carried out to gain further insight
into the CO2 dynamics in LiY and NaY Faujasites. In both materials, it was pointed out that the transport diffusivity (DT) increases with the loading whereas the self diffusivity (DS) decreases. In addition, it was shown that LiY exhibits a significant slower CO2 self diffusivity process due to a strong interaction between the Li+ cation and the adsorbate molecules at the initial stage of diffusion. This result is consistent with higher simulated activation
energy in this cation exchanged faujasite form. By contrast, the transport diffusivity is revealed to be slightly faster in
LiY than in NaY. 相似文献
42.
ER Badman GE Patterson JM Wells RE Santini RG Cooks 《Journal of mass spectrometry : JMS》1999,34(8):889-894
Dual-detector differential non-destructive Fourier transform detection in a quadrupole ion trap is shown to improve signal intensity and reduce noise compared with spectra recorded using a single detector. A larger area detector in each end-cap electrode is machined to fit its hyperbolic shape and so minimize field imperfections on the z-axis. Argon, acetophenone and bromobenzene spectra were recorded to allow a comparison between single- and dual-detector (differential) modes of detection and to demonstrate the improvement achieved with differential detection. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
43.
Christopher Plant James E. Boggs John N. Macdonald Gwilym A. Williams 《Structural chemistry》1992,3(1):3-8
In this report the effects of basis set size and electron correlation on the internal rotation barrier heights in ethene thiol are investigated and compared with experimental data. At all levels of theory reasonable agreement is obtained for the barrier tosyn/anti rotation (experimental value: 9.6 kJ/mol), however, theanti barrier (experimental value: 0.14 kJ/mol) is consistently overestimated by approximately a factor of 10. A comparison of ab initio predictions of torsional energy distributions and rotational constant variations as a function of torsional state with the corresponding experimental quantities is presented. 相似文献
44.
G. Maurin D. Plant S. Devautour-Vinot A. Nicolas F. Henn J. C. Giuntini 《The European physical journal. Special topics》2007,141(1):113-116
Molecular Dynamics simulations have been carried out to
address the question of cation migration upon adsorption of methanol in NaY
Faujasite system as a function of the loading. It has been shown that at low
and intermediate loadings, SII cations can migrate toward the center of the
supercage due strong interaction with the adsorbates, followed by hopping of
SI' cations from the sodalite cage into the supercage to fill vacant SII
sites. SI cations mainly remain trapped in their initial sites whatever the
loading. At higher loading, only limited motion is observed for SII cations
due to steric effects induced by the adsorbates within the supercage. These
simulated results are in good agreement with those extracted by Complex
Impedance Spectroscopy measurements, which provided the evolution of the
number of extraframework cations in the different crystallographic sites as
a function of the treatment temperature. 相似文献
45.
46.
Two New Saponins from Lysimachia davurica 总被引:3,自引:0,他引:3
JingKuiTIAN ZhongMeiZOU LiZhenXU GuangHongTU HongWuZHANG ShiLinYANG DongGeAN 《中国化学快报》2005,16(2):212-214
Two new saponins named davuricoside I (1) and davuricoside E (2) were isolated from the whole plants ofLysimachia davurica. Their structures were determined by 1D and 2D NMR, FAB-MS techniques, and chemical methods. 相似文献
47.
Raymond J. Abraham James Plant Geoffrey R. Bedford 《Magnetic resonance in chemistry : MRC》1982,19(4):204-210
The preparation, isolation and characterization by proton and 13C NMR of the four possible atropisomers of meso-tetra(2-methoxy-1-naphthyl)porphyrin is described. Chemical shift differences due to atropisomerization effects are observed in the porphyrin and naphthyl rings. Comparison of the naphthyl chemical shifts with those of the model compound 1-isopropenyl-2-methoxynaphthalene allows the shifts due to the porphyrin ring current to be isolated. The observed Δδ values of the naphthyl protons agree well with those calculated from the previously described porphyrin ring current model, and allow both the angle of tilt of the naphthyl ring and the dihedral angle of the 2-methoxy substituent to be estimated. In contrast, the Δδ values for the naphthyl carbons bear no relationship to the calculated ring current shifts. Calculations of the total ring current contribution (porphyrin plus naphthyl rings) at the different naphthyl rings of the unsymmetric type III isomer show that at least part of the observed atropisomerism effects are due to the long-range current shifts of the naphthyl rings. The results also provide a clear demonstration of the identity of the porphyrin ring current in the free base and porphyrin dication. 相似文献
48.
H. Heller H. Clever G. T. Piercy E. K. Plant M. C. Rogers S. Zweig A. Taub J. D. White F. W. Rose Jr. und K. S. Nitsche 《Fresenius' Journal of Analytical Chemistry》1943,125(1-2):66-68
Ohne Zusammenfassung 相似文献
49.
50.
Xing Li Zhang Yang Yang Liu Jian He Wei Yun Yang Zheng Zhang Jun Qing Huang Huai Qiong Chen Yu Jun Liu 《中国化学快报》2012,23(6):727-730
We used whole-tree agarwood-induction technology to produce agarwood from Aquilaria sinensis trees within 20 months,and evaluated the quality of this agarwood.The results showed its characteristics were similar to those of high-grade wild agarwood in terms of texture,chemical constituents,essential oil content,and ethanol-soluble extract content,with the lattermost quality far surpassing the requirement of traditional Chinese medicine agarwood,as indicated in Chinese Pharmacopoeia 2010.To the best of our knowledge,this is first study to show that high-quality agarwood can be produced in whole A.sinensis trees via a chemically induced technology. 相似文献