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2,028 results on '"Qu,Jian"'

202. Chemical coating polysaccharide on gigaporous polystyrene microspheres as a high-speed protein chromatography matrix

Author

Qu, Jian-Bo, Xu, Yu-Liang, Liu, Jun-Yi, Li, Shi-Hai, Zhou, Wei-Qing, and Liu, Jian-Guo

Subjects
Chromatography -- Technology application, Polysaccharides -- Usage, Microspheres -- Production processes, Technology application, Engineering and manufacturing industries, Science and technology
Abstract

Permanent polysaccharide coating on gigaporous polystyrene (PS) microspheres was achieved through direct chemical grafting of dextran via a facile method, minimizing nonspecific adsorption of proteins and providing easily derivatizable groups on microspheres. Chloroacetylated PS microspheres (PS-CI) were first developed through acetylation, and hydrophilic dextran was directly grafted to hydrophobic PS-CI via a Williamson reaction (PS-Dex). The homogeneous side-bound dextran coating has the advantage of masking the hydrophobic surface of the PS microspheres, while maintains their original gigaporous structure. After grafting, the hydrophobic surface of the PS microspheres was effectively masked, and nonspecific protein adsorption was greatly reduced. Moreover, the hydroxyl-rich coating can be easily derivatized through classical chemical methods. A column packed with PS-Dex presented both good permeability and mechanical strength at high flow velocities of up to 3612 cm/h. These results implied that PS-Dex should be an ideal matrix for high-speed protein chromatography., INTRODUCTION Downstream processing in modern biotechnology, as represented by large-scale purification and separation of biomolecules, consumes up to 70% or more of the total processing cost in the production of [...]

Published
2016
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203. On Smartly Scanning of the Internet of Things

Author

Qu, Jian, Ma, Xiaobo, Liu, Wenmao, Sang, Hongqing, Li, Jianfeng, Xue, Lei, Luo, Xiapu, Li, Zhenhua, Feng, Li, and Guan, Xiaohong

Abstract

Cyber search engines, such as Shodan and Censys, have gained popularity due to their strong capability of indexing the Internet of Things (IoT). They actively scan and fingerprint IoT devices for unearthing IP-device mapping. Because of the large address space of the Internet and the mapping’s mutative nature, efficiently tracking the evolution of IP-device mapping with a limited budget of scans is essential for building timely cyber search engines. An intuitive solution is to use reinforcement learning to schedule more scans to networks with high churn rates of IP-device mapping. However, such an intuitive solution has never been systematically studied. In this paper, we take the first step toward demystifying this problem based on our experiences in maintaining a global IoT scanning platform. Inspired by the measurement study of large-scale real-world IoT scan records, we land reinforcement learning onto a system capable of smartly scanning IoT devices in a principled way. We disclose key parameters affecting the effectiveness of different scanning strategies, and real-world experiments demonstrate that our system can scan up to around 40 times as many IP-device mapping mutations as random/sequential scanning.

Published
2024
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204. Website Fingerprinting on Encrypted Proxies: A Flow-Context-Aware Approach and Countermeasures

Author

Ma, Xiaobo, Qu, Jian, Shi, Mawei, An, Bingyu, Li, Jianfeng, Luo, Xiapu, Zhang, Junjie, Li, Zhenhua, and Guan, Xiaohong

Abstract

Website fingerprinting (WFP) could infer which websites a user is accessing via an encrypted proxy by passively inspecting the traffic characteristics of accessing different websites between the user and the proxy. Designing WFP attacks is crucial for understanding potential vulnerabilities of encrypted proxies, which guides the design of defensive measures against WFP. In this paper, we design a novel WFP attack against (popular) encrypted proxies that relay connections between the user and the proxy individually (e.g., Shadowsocks, V2Ray), and accordingly implement lightweight countermeasures to effectively defend against the attack. The attack features flow-context-aware and is both accurate and immediately deployable, because it fully considers the obstacle (dubbed training-testing asymmetry) that fundamentally limits the practicability of WFP and addresses the obstacle with built-in spatial-temporal flow correlation mechanism. We implement the countermeasure as middleboxes installed on both the client and server sides of encrypted proxies, without altering any existing infrastructures for compatibility. The middleboxes can obfuscate a website’s flow regularities across different visits. Large-scale experiments in real-world scenarios demonstrate that the WFP attack can generally achieve a detection rate above 98.8% with a false positive rate below 0.2%. The countermeasure forces the attack’s false positive rate to be above 0.2 and true positive rate to be below 0.9 with just five persistent TCP connections while introducing very limited bandwidth overhead (e.g., 0.49%) and almost-zero additional network latency.

Published
2024
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228. Modeling nonlinear viscoelastic responses of flexible composites for soft robotics applications.

Author

Qu, Jian, Khan, Kamran, Meng, Songhe, and Muliana, Anastasia

Subjects
*SOFT robotics, *FIBER orientation, *DEFORMATIONS (Mechanics), *ROBOT design & construction, *PNEUMATIC actuators, *STRUCTURAL components
Abstract

This study examines the deformation of soft composites comprising stiff elastic unidirectional fibers and soft matrix, such as silicone elastomer, rubber and PDMS (Sylgard 184) with potential applications for soft robots. In some soft robotic applications, precise controls of shape reconfigurations are necessary. To design soft robots with high precision motions, it requires a detailed understanding of material responses. In this study, we formulate a constitutive model for the nonlinear viscoelastic response for soft isotropic materials, which is used for the soft matrix in the composites. We examine mechanical deformations of soft composite laminas with two different matrices i.e., Ecoflex 00-30 and PDMS (Sylgard 184), which differ significantly in their extensibility, and different fiber orientations. The initial fiber orientation and matrix extensibility govern the shape reconfigurations of the laminas. The viscoelastic response of the soft matrix causes continuous shape reconfigurations associated with the creep behaviors, which influence the final shapes of the lamina. We also present the design and analyses of soft composite structural components, incorporating the nonlinear viscoelastic responses of the matrix. [ABSTRACT FROM AUTHOR]

Published
2023
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248. Polymyxin B-Based Regimens for Patients Infected with Carbapenem-Resistant Gram-Negative Bacteria: Clinical and Microbiological Efficacy, Mortality, and Safety

Author

Qu,Jian, Qi,Ting-Ting, Qu,Qiang, Long,Wen-Ming, Chen,Ying, Luo,Yue, Wang,Ying, Qu,Jian, Qi,Ting-Ting, Qu,Qiang, Long,Wen-Ming, Chen,Ying, Luo,Yue, and Wang,Ying

Abstract

Jian Qu,1,2 Ting-Ting Qi,1,2 Qiang Qu,3,4 Wen-Ming Long,5 Ying Chen,6 Yue Luo,7 Ying Wang1,2 1Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, 410011, People’s Republic of China; 2Institute of Clinical Pharmacy, Central South University, Changsha, 410011, People’s Republic of China; 3Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410078, People’s Republic of China; 4National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410078, People’s Republic of China; 5Department of Pharmacy, Jingzhou District, Second People’s Hospital of Huaihua City, Huaihua, 418400, People’s Republic of China; 6Department of Pharmacy, Wuhan University, Renmin Hospital, Wuhan, 430060, People’s Republic of China; 7Department of Pharmacy, The People’s Hospital of Liuyang, Liuyang, 410300, People’s Republic of ChinaCorrespondence: Ying Wang, Department of Pharmacy, The Second Xiangya Hospital, Central South University, Institute of Clinical Pharmacy, Central South University, No. 139 Middle Renmin Road, Changsha, 410011, People’s Republic of China, Tel +86-15173198700, Fax +86-731-85292072, Email wangying5211@csu.edu.cnBackground: The increasing prevalence of carbapenem-resistant Gram-negative bacteria (CR-GNB) represents a global healthcare crisis. This study explored the efficacy and safety of Polymyxin B (PMB)-based regimens and factors influencing their effectiveness.Methods: Patients with CR-GNB infections treated with PMB for more than three days were enrolled in this retrospective study from 1st June 2018 to 30th April 2020. Data were collected on patient characteristics, bacterial culture, and drug-sensitivity test results; anti-infection treatment regimens, particularly details of PMB use; and adverse drug reactions. Clinical and microbiological efficacy, mortality, and safety of PMB-based regimens in CR-GNB infected patients were evaluated.

Published
2022

249. Nephrotoxicity and Efficacy Assessment of Polymyxin B Use in Renal Transplant Patients

Author

Wen,Yu-Xin, Qu,Qiang, Long,Wen-Ming, Luo,Yue, Zhuang,Hai-Hui, Teng,Xin-Qi, Qu,Jian, Wen,Yu-Xin, Qu,Qiang, Long,Wen-Ming, Luo,Yue, Zhuang,Hai-Hui, Teng,Xin-Qi, and Qu,Jian

Abstract

Yu-Xin Wen,1,2,* Qiang Qu,3,4,* Wen-Ming Long,5 Yue Luo,6 Hai-Hui Zhuang,1 Xin-Qi Teng,1 Jian Qu1 1Department of Pharmacy, The Second Xiangya Hospital, Central South University; Institute of Clinical Pharmacy, Central South University, Changsha, 410011, People’s Republic of China; 2Department of Pharmacy, Lixian People’s Hospital in Hunan, Lixian, 415500, People’s Republic of China; 3Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410078, People’s Republic of China; 4National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410078, People’s Republic of China; 5Department of Pharmacy, Jingzhou District, Second People’s Hospital of Huaihua City, Huaihua, 418400, People’s Republic of China; 6Department of Pharmacy, The People’s Hospital of Liuyang, Liuyang, 410300, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jian QuDepartment of Pharmacy, The Second Xiangya Hospital, Central South University; Institute of Clinical Pharmacy, Central South University, No. 139 Middle Renmin Road, Changsha, 410011, People’s Republic of China, Tel +86-15973190614, Fax +86-731-85292072Email qujianstanley@csu.edu.cnPurpose: This study investigates the nephrotoxicity and efficacy assessment of polymyxin B (PMB) use in renal transplant patients.Patients and Methods: This retrospective study included adult (> 18 years of age) renal transplant patients who received PMB intravenous drip for more than 72 hours. Efficacy assessment of PMB included clinical treatment efficacy, microbiological efficacy at the end of PMB treatment, and in-hospital all-cause mortality. Nephrotoxicity of PMB was evaluated for further group comparison.Results: We enrolled 235 renal transplant patients in our study. After PMB treatment, 45 patients occurred PMB-nephrotoxicity, and the nephr

Published
2022

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