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Hu B.,CAS Qinghai Institute of Salt Lakes
Russian Journal of Physical Chemistry A | Year: 2013

The Pitzer ion-interaction extended by Harvic and Weare was applied to predict the solubility isotherms of reciprocal quaternary systems in which mixed crystals are formed. On the basis of data concerning the binary and ternary subsystems, the four components systems Rb+, Cs+/Cl -, SO4 2- -H2O, and K+, Cs+/Cl-, SO4 2- -H2O were investigated at 25 C.The results of calculation can be used to model salt crystallization during the concentration of brines. © 2013 Pleiades Publishing, Ltd. Source

Zeng F.,CAS Qinghai Institute of Salt Lakes
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2016

Late Quaternary loess deposit is widely distributed in the Qinghai Lake region and adjacent area. The loess deposit independently recorded the environmental and climatic changes during the late Quaternary in the Qinghai Lake region, northeastern Qinghai-Tibetan Plateau. Nearly all studies are focused on reconstructing the environmental and climatic changes recorded by loess deposit in the Qinghai Lake region. However, up to now, the provenance of the loess deposit in the Qinghai Lake region is still poorly understood. Here we present the elemental concentration of the silicate fraction of the eolian deposit (<75 μm) from the ZYC section in the Qinghai Lake region and LT section at Lintao County on the western Chinese Loess Plateau, loess deposits at Guanjiaoshan Mountain, Chaka town and Wulan County, eolian sands at western and eastern shore of the Qinghai Lake, and fluvial deposits from the Buhahe river and lacustrine deposits at Erlangjian site in the Qinghai Lake region. The results show that: (1) K2O/Al2O3 (molar ratio) and Zr/Ti, Zr/Nb ratios indicate that the eolian deposits in the Qinghai Lake region and adjacent area can be distinguished clearly from the local deposits represented by river deposits at Buhahe river and lacustrine deposits at Erlangjian in the drainage basin of Qinghai Lake; (2) There is similarity of the elemental ratios (K2O/Al2O3 and Zr/Ti, Zr/Nb) between the eolian deposits in the Qinghai Lake region and loess deposits at Lintao County. Thus, the eolian deposits in the Qinghai Lake region and Lintao County may have the same source region; (3) Late Quaternary loess deposit in the Qinghai Lake region is probably sourced from the Qaidam basin. © 2016, Editorial Department of Earth Science. All right reserved. Source

Li X.,CAS Institute of Earth Environment | Liu W.,CAS Institute of Earth Environment | Liu W.,Xian Jiaotong University | Xu L.,CAS Qinghai Institute of Salt Lakes
Chemical Geology | Year: 2012

To further investigate the significance of carbon isotopes of lake carbonates in arid areas, we examined the carbon isotopic composition of ostracods, bulk carbonate, fine-grained carbonates, and associated water DIC (dissolved inorganic carbon) from Lake Qinghai and several small lakes and ponds surrounding Lake Qinghai. We obtained three major results. 1) The carbon isotopic compositions of ostracods, bulk carbonate, and fine-grained carbonates in the lakes and ponds are clearly correlated with water δ 13C DIC values, which vary with water salinity in the Lake Qinghai area. 2) The variation in the δ 13C DIC values of lake water is mainly controlled by CO 2 exchanges between the atmosphere and lake waters in the Lake Qinghai area. 3) Ostracods, bulk carbonate and fine-grained carbonates show consistent trends of isotopic composition in the study area, and the differences in carbon isotopic composition between authigenic carbonates and ostracods may be explained by the differences in carbon isotopic composition between the DIC of surface water and that of the water near to the sediment-water interface as well as the 'vital offsets' of ostracods.Our results suggest that variations in the δ 13C values of carbonates in Lake Qinghai and other lakes in this arid, high-altitude area are primarily controlled by the carbon-isotope ratios of the lake water DIC, which in turn are related to water salinity. Therefore, changes in carbonate δ 13C values may be used to indirectly indicate changes in water salinity in the Lake Qinghai area. © 2012 Elsevier B.V.. Source

Huang G.,Wenzhou University | Huang G.,CAS Qinghai Institute of Salt Lakes | Cheng B.,Wenzhou University | Xu L.,Wenzhou University | And 2 more authors.
Chemistry - A European Journal | Year: 2012

A comprehensive mechanistic study of the InCl 3-, AuCl-, and PtCl 2-catalyzed cycloisomerization of the 2-(haloethynyl)biphenyl derivatives of Fürstner et al. was carried out by DFT/M06 calculations to uncover the catalyst-dependent selectivity of the reactions. The results revealed that the 6-endo-dig cyclization is the most favorable pathway in both InCl 3- and AuCl-catalyzed reactions. When AuCl is used, the 9-bromophenanthrene product could be formed by consecutive 1,2-H/1,2-Br migrations from the Wheland-type intermediate of the 6-endo-dig cyclization. However, in the InCl 3-catalyzed reactions, the chloride-assisted intermolecular H-migrations between two Wheland-type intermediates are more favorable. These Cl-assisted H-migrations would eventually lead to 10-bromophenanthrene through proto-demetalation of the aryl indium intermediate with HCl. The cause of the poor selectivity of the PtCl 2 catalyst in the experiments by the Fürstner group was predicted. It was found that both the PtCl 2-catalyzed alkyne-vinylidene rearrangement and the 5-exo-dig cyclization pathways have very close activation energies. Further calculations found the former pathway would lead eventually to both 9- and 10-bromophenanthrene products, as a result of the Cl-assisted H-migrations after the cyclization of the Pt-vinylidene intermediate. Alternatively, the intermediate from the 5-exo-dig cyclization would be transformed into a relatively stable Pt-carbene intermediate irreversibly, which could give rise to the 9-alkylidene fluorene product through a 1,2-H shift with a 28.1 kcal mol -1 activation barrier. These findings shed new light on the complex product mixtures of the PtCl 2-catalyzed reaction. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Xia Y.,Wenzhou University | Huang G.,Wenzhou University | Huang G.,CAS Qinghai Institute of Salt Lakes
Journal of Organic Chemistry | Year: 2010

The reaction mechanisms of the PtCl4- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the acceleration effect of ethanol solvent in PtCl4-catalyzed reaction and the different catalytic activities of Au and Pt catalysts. Calculations indicate the rate of the PtCl 4-catalyzed reaction in noncoordinative solvent of 1,2-dichloroethane is limited by isomerization of the relatively stable chelate complex to the reactive π-complex of PtCl4 with the acetylenic moiety of homopropargyl azide substrate, which requires an activation energy of 29.6 kcal/mol. All nucleophilic cyclization, dinitrogen elimination, and 1,2-H shift of metal-carbene steps are quite facile. The generation of 2H-pyrrole intermediate in PtCl4-catalyzed reaction is completed by a ligand substitution reaction, and the final 2H-pyrrole to 1H-pyrrole isomerization is an intermolecular process with another 2H-pyrrole as a proton shuttle. When in ethanol solution, the favorable coordination of solvent molecules with PtCl 4 could inhibit the chelation of PtCl4 with the homopropargyl azide. Besides, the alcohol coordination also facilitates the generation of 2H-pyrrole intermediate and the intermolecular isomerization of 2H-pyrrole to 1H-pyrrole. Consequently, the overall activation barrier of PtCl4-catalyzed reaction in ethanol solution is lowered to 21.5 kcal/mol, determined by the H-abstraction step of the intermolecular 2H-pyrrole to 1H-pyrrole isomerization. The basic steps in the Au(I)-catalyzed reaction are similar to those in the PtCl4-catalyzed one. However, no chelate complex could be formed from PR3AuSbF6 and homopropargyl azide, and the 2H-pyrrole generation step is much more favorable, indicating weaker interactions of Au(I) catalyst with the homopropargyl azide and the C-C double bond of 2H-pyrrole. © 2010 American Chemical Society. Source

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