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RISS 인기검색어
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- 저자 : Xuejun Tian (검색결과 5 건)
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A Framework for measuring query privacy in Location-based Service
( Xuejun Zhang ),( Xiaolin Gui ),( Feng Tian ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.5
The widespread use of location-based services (LBSs), which allows untrusted service provider to collect large number of user request records, leads to serious privacy concerns. In response to these issues, a number of LBS privacy protection mechanisms (LPPMs) have been recently proposed. However, the evaluation of these LPPMs usually disregards the background knowledge that the adversary may possess about users` contextual information, which runs the risk of wrongly evaluating users` query privacy. In this paper, we address these issues by proposing a generic formal quantification framework,which comprehensively contemplate the various elements that influence the query privacy of users and explicitly states the knowledge that an adversary might have in the context of query privacy. Moreover, a way to model the adversary`s attack on query privacy is proposed, which allows us to show the insufficiency of the existing query privacy metrics, e.g., k-anonymity. Thus we propose two new metrics: entropy anonymity and mutual information anonymity. Lastly, we run a set of experiments on datasets generated by network based generator of moving objects proposed by Thomas Brinkhoff. The results show the effectiveness and efficient of our framework to measure the LPPM.
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Catalytic transfer hydrogenation of 7-ketolithocholic acid to ursodeoxycholic acid with Raney nickel
He Tian,Xuejun Cao,Hongbin Zhao 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
Ursodeoxycholic acid was produced by the stereoselective reduction of 7-ketolithocholic acid. This hydrogenation reaction was catalyzed by the T-1 Raney nickel and potassium borohydride was used as hydrogen donor instead of inflammable hydrogen gas. Potassium tert-butoxide was introduced to improve yield of ursodeoxycholic acid from about 70% to a maximum of 94% by inducing the stereoselectivity on hydroxyl group at 40 8C and atmospheric pressure. Reduction reaction conditions such as amount of reactants, temperature and stirring speed were optimized. The whole process is safe and low-cost. Eventually, the product, ursodeoxycholic acid was characterized by IR, 1H NMR and 13C NMR spectra.
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Wene Zhang,Zhiguo Tian,Xuejun Pan,Xiuming Zhao,Fei Wang 한국원예학회 2013 Horticulture, Environment, and Biotechnology Vol.54 No.1
The physiological responses of three edible canna cultivars (Canna edulis ker. cv. ‘PLRF’, ‘Xingyu-1’, and ‘Xingyu-2’) to continuous drought stress for 35 days were investigated by characterizing the water saturation deficit (WSD), relative electrical conductivity (REC), superoxidative radical content (SRC), ascorbic acid (AsA) content,glutathione (GSH) content and protein content. It was observed that WSD, REC, SRC progressively increased in the upper leaves of three cultivars under both control and drought treatments. The content changes of AsA, GSH and water soluble protein were lower in ‘Xingyu-2’ than in ‘Xingyu-1’ and ‘PLRF’, in upper leaves than in lower leaves. Compared with control, drought stress aggravated these physiological changes in all three cultivars. The correlation analysis showed that there were significant correlations between indexes except for protein content, which significantly correlated only with SRC. These indicated that drought stress directly led to water loss, and then the REC increased, while the GSH and AsA played major roles in removing the SRC. These results revealed that ‘Xingyu-2’ was more tolerant to drought stress than ‘PLRF’ and ‘Xingyu-1’,and the lower leaves were more sensitive than the upper leaves. The present study not only provides new insights into mechanisms of acclimation and tolerance to drought stress in edible canna but also provides clues for improving drought tolerance of edible canna through breeding or genetic engineering.
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Ji Wanqing,Wu Zhiru,Wen Jiaming,Tang Hengxin,Chen Zhuopeng,Xue Bo,Tian Zhenming,Ba Yueyang,Zhang Ning,Wen Xuejun,Hou Bo 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
The brain vascular basement membrane (brain-VBM) is an important component of the brain extracellular matrix, and the three-dimensional structure of the cerebrovascular network nested with many cell-adhesive proteins may provide guidance for brain tissue regeneration. However, the potential of ability of brain-VBM to promote neural tissue regeneration has not been examined due to the technical difficulty of isolating intact brain-VBM.The present study developed a simple, effective method to isolate structurally and compositionally intact brain-VBM. Structural and component properties of the brain-VBM were characterized to confirm the technique. Seed cells were cocultured with brain-VBM in vitro to analyze biocompatibility and neurite extension. An experimental rat model of focal traumatic brain injury (TBI) induced by controlled cortical impact were conducted to further test the tissue regeneration ability of brain-VBM.Brain-VBM isolated using genipin showed significantly improved mechanical properties, was easy to handle, supported high cell viability, exhibited strong cell adhesive properties, and promoted neurite extension and outgrowth. Further testing of the isolated brain-VBM transplanted at lesion sites in an experimental rat model of focal TBI demonstrated considerable promise for reconstructing a complete blood vessel network that filled in the lesion cavity and promoting repopulation of neural progenitor cells and neurons.The technique allows isolation of intact brain-VBM as a 3D microvascular scaffold to support brain tissue regeneration following TBI and shows considerable promise for the production of naturally-derived biomaterials for neural tissue engineering.
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Isolation and characterization of heat-responsive gene TaGASR1 from wheat (Triticum aestivum L.)
Liyuan Zhang,Xiaoli Geng,Haiyan Zhang,Chunlei Zhou,Aiju Zhao,Fei Wang,Yue Zhao,Xuejun Tian,Zhaorong Hu,Mingming Xin,Yingyin Yao,Zhongfu Ni;Qixin Sun,Qixin Sun,Huiru Peng 한국식물학회 2017 Journal of Plant Biology Vol.60 No.1
GA-stimulated transcript (GAST) family genes have been identified in numerous plant species. In this paper, we isolated and characterized a heat-responsive gene, TaGASR1, from heat tolerant variety TAM107. The complete ORF of TaGASR1 was cloned, which encoded a 98-kDa protein, and the sequence shared 51.52% similarity to OsGASR1. Analysis of the TaGASR1 promoter region showed that it contained a heat shock element (HSE) and several cis-elements involved in abiotic stress response and hormone signal transduction. Expression patterns of TaGASR1 revealed that it was strongly induced by stress factors, such as high temperature, drought, high salinity and oxidation, as well as the phytohormones, including MeJA, ACC and ABA, which suggested the TaGASR1 gene might participate in these stress and hormone signal transduction pathways. Transient expression of TaGASR1-GFP fusion proteins in onion epidermal cells indicated that TaGASR1 protein was localized to the cell membrane or cytosol. Further analysis showed that ectopic expression of TaGASR1 in Arabidopsis enhanced thermotolerance and reduced the accumulation of reactive oxygen species (ROS) after heat stress. Moreover, we also found that TaGASR1-overexpressing wheat improved tolerance to heat stress and oxidative stress.
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