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Urunchi, China

Xinjiang University is one of the major universities in the Xinjiang Uyghur Autonomous Region, People’s Republic of China, and is a national key university. Established in 1924 and located in Urumqi, Xinjiang University is a comprehensive university with the highest academic level in Xinjiang, under Project 211. Wikipedia.

Two bis(tetrazole) ligands, 1,2-bis(tetrazol-5-ylmethyl)benzene (H 2L 1) and 1,2-bis(tetrazol-5-yl)benzene (H 2L 2), were designed and synthesized, and three new zinc(II) and cadmium(II) coordination polymers, {[Zn 2(L 1) 2(H 2O) 2] 2· 8H 2O} ∞ (1), [Zn 4(L 1) 4] ∞ (2) and {[Cd(L 2)(NH 3) 3]·2H 2O} ∞ (3), were synthesized using the ligands H 2L 1 and H 2L 2 as building blocks. All the complexes were structurally characterized by elemental analyses, IR spectroscopy and X-ray diffraction. Complexes 1 and 3 have infinite one-dimensional (1-D) chain structures, and such 1-D chains structures were linked by complicated hydrogen bonds to form three-dimensional (3-D) supermolecular networks. Complex 2 has a 3-D network structure. In these complexes, the ligands H 2L 1 and H 2L 2 can act as multidentate ligands when coordinating to the metal ions under different conditions, and three coordination modes for the tetrazolate rings have been observed in these complexes. The results show that the variation of the ligand spacers as well as the reaction conditions lead to the formation of complexes with different structures. Furthermore, the fluorescent properties of complexes 1-3 and ligands H 2L 1 and H 2L 2 have been investigated and discussed. © 2012 Elsevier Ltd. All rights reserved.

Liu F.,Qinghai Normal University | Feng Z.,Xinjiang University
Holocene | Year: 2012

Our review of recently published climatic proxy sequences shows that the most dramatic climate tranistion of the mid Holocene (~8500-~3500 cal. yr BP) occurred at the middle- to late-Holocene transition at ~4000 cal. yr BP. In northern China, an abrupt climatic shift at ~4000 cal. yr BP was recorded in the eastern margin of the Tibetan Plateau, in the western part of the Chinese Loess Plateau and in the vast Inner Mongolian Plateau. In southern China, the ~4000 cal. yr BP event was also abrupt, but it is expressed as one of several quasi-cyclic events in most of the records. We propose that the cumulative effects of insolation-dictated declining trend in tropical SST and the geologically documented increasing trend of ENSO activity were the first-order causes of the cooling and the associated drying during the past 6000 years. Superimposed on the first-order causes were the second-order causes, i.e. the additive effects of the 'Bond Event 3'-associated lower insolation and the increasingly drying-resulted negative feedback of 'air-land interactions'. The second-order causes made ~4000 cal. yr BP the tipping point when the resultant drying had destroyed many Chinese Neolithic cultures. Our review of published archaeological literature shows that six of the seven well-documented Chinese Neolithic cultures collapsed at ~4000 cal. yr BP with the exception of the Henan Longshan Culture that evolved to the more advanced Erlitou Culture. The indicators of the cultural collapse include (1) the number of archaeological sites was significantly reduced, (2) the quality of the archaeological artifacts of the succeeding culture is lower than that of the preceding culture, (3) more sophisticated architectures disappeared, and (4) agricultural cultures were replaced by pastoralism or by agro-pastoralism in northern China. © The Author(s) 2012.

Kerim A.,Xinjiang University
New Journal of Chemistry | Year: 2014

The aromaticity of porphyrazine (PA) and its three triazoleporphyrazine (TAP) tautomers as well as their metal complex compounds was examined using the TRE (topological resonance energy) and the MRE (magnetic resonance energy) methods. Their local aromaticity was studied using the BRE (bond resonance energy) and the CRE (circuit resonance energy) methods. The relationship between the global and local aromaticity of TAPs and the position of the substituted nitrogen atom is discussed. The results of these calculations are compared with those provided by other aromaticity indices. Our TRE and MRE results indicate that PA and TAPs possess lower global aromaticity than porphyrin. Our BRE and CRE results show that global aromaticity is closely associated primarily with the five-membered rings which contain the -NH- pyrrolic rings, and the [18]-annulene-like conjugation pathway is not crucial for determining the aromaticity of the entire π-system. Moreover, the circuit-current susceptibility (χi) and ring current (RC) were obtained using the graph-theoretical method. The χi and RC results show that all the compounds sustain a diatropic current along the macrocycle and this current is bifurcated when it passes through every five-membered ring. Ring current maps reveal that in the five-membered rings, the ring current prefers to pass through the C-C bond when the ring contains an -NH- group, and through the C-N bond when the ring does not contain an -NH- group. © 2014 the Partner Organisations.

Wu B.,Xinjiang University
Match | Year: 2010

The Wiener index W(G) of a connected graph G is the sum of distances of all pairs of vertices in G. We show that for any connected graph G with (5(G) The Wiener index W(G) of a connected graph G is the sum of distances of all pairs of vertices in G. We show that for any connected graph G with δ(G) ≥ 2, W(L(G)) ≥ W(G), with equality if and only if G is a cycle, where L(G) is the line graph of G. We also present lower and upper bounds for JV(L(G)) in terms of a graph invariant called Gutman index of G. As an immediate consequence, a relation between Gutman index and Wiener index of a tree is derived.

Yang Z.-X.,Xinjiang University
International Journal of Pattern Recognition and Artificial Intelligence | Year: 2013

In this paper, we propose two Laplacian nonparallel hyperplane proximal classifiers (LapNPPCs) for semi-supervised and full-supervised classification problem respectively by adding manifold regularization terms. Due to the manifold regularization terms, our LapNPPCs are able to exploit the intrinsic structure of the patterns of the training set. Furthermore, our classifiers only need to solve two systems of linear equations rather than two quadratic programming (QP) problems as needed in Laplacian twin support vector machine (LapTSVM) (Z. Qi, Y. Tian and Y. Shi, Neural Netw. 35 (2012) 46-53). Numerical experiments on toy and UCI benchmark datasets show that the accuracy of our LapNPPCs is comparable with other classifiers, such as the standard SVM, TWSVM and LapTSVM, etc. It is also the case that based on our LapNPPCs, some other TWSVM type classifiers with manifold regularization can be constructed by choosing different norms and loss functions to deal with semi-supervised binary and multi-class classification problems. © 2013 World Scientific Publishing Company.

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