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Xi'an, China

Northwest University , located in Xi'an city, Shaanxi Province, is one of the nation's leading comprehensive universities. Founded in 1902, it is one of the oldest institutions of learning in Northwest China.Presently, the university has 11 colleges, 33 departments, 63 Bachelor's and Associate's programs. Its student population amounts to 18,000, including about 2000 Ph.D. and master students, and about 100 international students.The university stresses international academic and personnel exchanges. Since the start of the Chinese economic reform in 1978, it has established cooperation and exchange relations with nearly 30 institutions of higher education of scientific research in the United States, Japan, United Kingdom, France, Germany, Italy, Russia, Canada, Australia, Switzerland, Hong Kong, Taiwan, and The Philippines. Wikipedia.

To elucidate how physiological and biochemical mechanisms of chilling stress are regulated by abscisic acid (ABA) pretreatment, pepper variety (cv. 'P70') seedlings were pretreated with 0.57 mM ABA for 72 h and then subjected to chilling stress at 10°/6°C (day/night). Chilling stress caused severe necrotic lesions on the leaves and increased malondialdehyde and H(2)O(2) levels. Activities of monodehydroascorbate reductase (DHAR), dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, ascorbate peroxidase, ascorbate, and glutathione increased due to chilling stress during the 72 h, while superoxide dismutase and catalase activities decreased during 24 h, suggesting that chilling stress activates the AsA-GSH cycle under catalase deactivation in pepper leaves. ABA pretreatment induced significant increases in the above-mentioned enzyme activities and progressive decreases in ascorbate and glutathione levels. On the other hand, ABA-pretreated seedlings under chilling stress increased superoxide dismutase and guaiacol peroxidase activities and lowered concentrations of other antioxidants compared with untreated chilling-stressed plants. These seedlings showed concomitant decreases in foliage damage symptoms, and levels of malondialdehyde and H(2)O(2). Induction of Mn-SOD and POD was observed in chilling-stressed plants treated with ABA. The expression of DHAR1 and DHAR2 was altered by chilling stress, but it was higher in the presence than in the absence of ABA at 24 h. Overall, the results indicate that exogenous application of ABA increases tolerance of plants to chilling-induced oxidative damage, mainly by enhancing superoxide dismutase and guaiacol peroxidase activities and related gene expression.

Zhai M.-G.,Northwest University, China | Zhai M.-G.,CAS Institute of Geology and Geophysics | Santosh M.,Kochi University
Gondwana Research | Year: 2011

The crustal growth and stabilization of the North China Craton (NCC) relate to three major geological events in the Precambrian: (1) a major phase of continental growth at ca. 2.7. Ga; (2) the amalgamation of micro-blocks and cratonization at ca. 2.5. Ga; and (3) Paleoproterozoic rifting-subduction-accretion-collision tectonics and subsequent high-grade granulite facies metamorphism-granitoid magmatism during ca. 2.0-1.82. The major period of continental growth during 2.9-2.7. Ga in the NCC correlates with the global growth of Earth's crust recognized from other regions. The enormous volume of tonalite-trondhjemite-granodiorite (TTG) rocks and associated komatiite-bearing magmatic suites developed during this period possibly suggest the manifestation of plume tectonics. The cratonization of the NCC at the end of Neoarchean at ca. 2.5. Ga (Archean-Proterozoic boundary) through the amalgamation of micro-blocks was accompanied by granulite facies metamorphism and voluminous intrusion of crustally-derived granitic melts leading to the construction of the basic tectonic framework of the NCC. Several Neoarchean greenstone belts surround the micro-blocks and represent the vestiges of older arc-continent collision. The next major imprint in the NCC is the Paleoproterozoic orogenic events during 2.35 -1.82 Ga which involved rifting followed by subduction -accretion -collision processes, followed by plume-triggered extension and rifting, offering important insights into modern-style plate tectonics operating in the Paleoproterozoic. Extreme crustal metamorphism and formation of high pressure (HP) and ultra-high temperature (UHT) orogens during 1950-1820. Ma accompanied the subduction-collision process and the suturing of continental blocks within the Paleoproterozoic supercontinent Columbia. Multiple subduction zones with opposing subduction polarity promoted the rapid assembly of crustal fragments of the NCC and their incorporation into the Columbia supercontinent. The HP and HT-UHT granulites demonstrate two main stages of metamorphism at ca. 1.95-1.89. Ga and at ca. 1.85-1.82. Ga, exhuming the basement rocks from lowermost crust level to the lower-middle crust level. With the emplacement of extensive mafic dyke swarms associated with continental rifting, and the intrusion of anorogenic magmatic suites, the evolution of the NCC into a stable continental platform was finally accomplished. © 2011 International Association for Gondwana Research.

Gao J.-M.,Northwest University, China | Yang S.-X.,Zhejiang Agriculture And forestry University | Qin J.-C.,Jilin University
Chemical Reviews | Year: 2013

Researchers survey the chemical and biological literature regarding the isolation, structure elucidation, biological activities, biosynthesis, and chemical synthesis of azaphilone derivatives from nature. The general methods for the synthesis of some natural azaphilone-like scaffolds are also discussed. Citrinin produced by several fungal species of genera Penicillium, Monascus, and Aspergillus, is widely considered as a hazardous contaminant of foods and feeds. A number of various derivatives of the citrinin family have been isolated from different P. citrinum strains and two Aspergillus species. The derivatives can be classified into four different categories on the basis of the degree of polymerization of the citrinin core, including monomeric citrinin congeners 2-6 and decarboxydihydrocitrinin.

Xu J.,Northwest University, China
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

Coherence arises from the superposition principle and plays a key role in quantum mechanics. Recently, Baumgratz et al. [T. Baumgratz, M. Cramer, and M. B. Plenio, Phys. Rev. Lett. 113, 140401 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.140401] established a rigorous framework for quantifying the coherence of finite-dimensional quantum states. In this work we provide a framework for quantifying the coherence of Gaussian states and explicitly give a coherence measure for Gaussian states based on the relative entropy. © 2016 American Physical Society.

Zhang H.-F.,Northwest University, China | Zhang H.-F.,CAS Institute of Geology and Geophysics
Gondwana Research | Year: 2012

Zircons from granulite xenoliths entrained in a Late Cretaceous mafic dike in the Jiaodong Peninsula, North China Craton (NCC), show three distinct U-Pb age populations. Part of the old zircon grains yield discordant data that project to ages of about 2.4 to 2.5Ga, a few grains indicate growth at about 2.0Ga and a third group yield Cretaceous ages with peaks at 120 and 90Ma. The oldest zircons give Hf TDM model ages of 2.6-2.8Ga. These results demonstrate the existence of original Archean lower crust in the Jiaodong region. Zircons of 2.0Ga have similar Hf TDM model ages as the Neoarchean-Paleoproterozoic grains, suggesting that these zircons were products of metamorphic recrystallization due to thermal event without juvenile input. Early Cretaceous zircons yield εHf(t) values of -21 to -12 and Late Cretaceous zircons large variable εHf(t) from +4 to -50. These data suggest that magmatic underplating occurred in the Neoarchean to Earliest Proterozoic lower crust of the NCC, both in the Early and Late Cretaceous. It is suggested that the Mesozoic magma underplating, which also provided the heat source for the voluminous Mesozoic magmatism in the NCC, significantly modified the composition of the Archean to Paleoproterozoic lower crust of the NCC. © 2011 International Association for Gondwana Research.

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