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A Novel β-1,4-N, 6-O-Diacetylmuramidase from Streptomyces griseus and its Chemical Modification

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Chinese Chemical Letters 2006年第11期17卷 1469-1472页

作者： Chang Kui SUN yu Zhen ZHANG ming chen State Key Laboratory of Microbial Technology Shandong University Ji＇nan 250100

A novel lysozyme named β-1, 4-N, 6-O-diacetylmuramidase R2 was purified and characterized from Streptomyces griseus. The molecular weight of the enzyme was determined by MALDI-TOF-MS as 23.5 kDa. The N-terminal amino acid sequence was DTSGVQGIDVSHWQG. Chemical modification of β-1, 4-N, 6-O-diacetylmuramidase R2 indicated that sulfhydryl group and carbamidine of arginine residues are not essential for the activity of the enzyme, but lysine residues and imidazole of histidine residues are essential for the activity. The number of essential tryptophan and carboxyl groups was found that only one tryptophan residue and three carboxyl groups in the active site.

关键词： Chemical modification β-1 4-N 6-O-diacetylmuramidase lysozyme.

Equivariant Normal Forms for Parameterized Delay Differential Equations with Applications to Bifurcation Theory

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Acta Mathematica Sinica,English Series 2012年第4期28卷 825-856页

作者： Shang Jiang GUO yu ming chen Jian Hong WU College of Mathematics and Econometrics Hu'nan University Department of Mathematics Wilfrid Laurier University Department of Mathematics and Statistics York University

In this paper, we develop an efficient approach to compute the equivariant normal form of delay differential equations with parameters in the presence of symmetry. We present and justify a process that involves center manifold reduction and normalization preserving the symmetry, and that yields normal forms explicitly in terms of the coefficients of the original system. We observe that the form of the reduced vector field relies only on the information of the linearized system at the critical point and on the inherent symmetry, and the normal forms give critical information about not only the existence but also the stability and direction of bifurcated spatiotemporal patterns. We illustrate our general results by some applications to fold bifurcation, equivariant Hopf bifurcation and Hopf-Hopf interaction, with a detailed case study of additive neurons with delayed feedback.

关键词： Equivariant delay differential equation normal form equilibrium stability bifurcation

Permeation of dimethyl sulfoxide into articular cartilage at subzero temperatures

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第3期13卷 213-220页

作者： Shao-zhi ZHANG Xiao-yi yu Guang-ming chen Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

Osteochondral allografting has been proved to be a useful method to treat diseased or damaged areas of joint surfaces. Operational long-term stocks of grafts which supply a buffer between procurement and utilization would contribute to the commercialization or industrialization of this technology. Vitrification has been thought to be a promising method for successful preservation of articular cartilage （AC）, but high concentration cryoprotectants （CPAs） are used which may cause high cellular toxicity. An effective way to reduce CPA toxioity is to increase CPA concen- tration gradually while the temperature is lowered. Understanding the mechanism of （31~A permeation at subzero temperatures is important for designing the cryopreservation protocol. In this research, the permeation of dimethyl sulfoxide （MezSO） in ovine AC at subzero temperatures was studied experimentally. Pretreated AC discs were ex- posed in Me2SO solutions for different time （0, 5, 15, 30, 50, 80, and 120 min） at three temperature levels （-10, -20, and -30℃）. The Me2SO concentration within the tissue was determined by ultraviolet （UV） spectrophotometry. The diffusion coefficients were estimated to be 0.85×10-6, 0.48×10-8, and 0.27×10-6 cm2/s at -10, -20, and -,30℃, respectively, and the corresponding activation energy was 29.23 kJ/mol. Numerical simulation was performed to com- pare two Me2SO addition protocols, and the results demonstrated that the total loading duration could be effectively reduced with the knowledge of permeation kinetics.

关键词： Articular cartilage Vitrification Dimethyl sulfoxide Permeation Diffusion coefficient Subzero temperature

Laparoscopic repair via the transabdominal preperitoneal procedure for bilateral lumbar hernia: Three cases report and review of literature

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World Journal of Clinical Cases 2018年第10期6卷 398-405页

作者： Di-yu Huang Long Pan ming-yu chen Jing Fang Department of General Surgery Sir Run-Run Shaw Hospital Zhejiang University Key Laboratory of Laparoscopic Technique Research of Zhejiang Province Sir Run-Run Shaw Hospital Zhejiang University

A lumbar hernia is a rare entity, and a bilateral lumbar hernia is much rarer. From May 2015 to October 2017, we treated only three patients with bilateral lumbar hernias. One patient came to the hospital presenting with right-sided abdominal pain, and the other two patients presented with bilateral lumbar masses. The previous bilateral lumbar hernia reported in the literature was repaired by open surgery. The laparoscopic approach via the transabdominal preperitoneal(TAPP) procedure with the self-gripping Parietex ProG rip? mesh was performed at our center. The laparoscopic repair was conducted by a skilled hernia surgeon, and was successfully performed in the three patients. The patients resumed a semiliquid diet and had no activity restriction after six hours following the operation. No antibiotics were used after the surgery. The operative times of the three patients were 120 min, 85 min, and 130 min. The blood loss volumes of the three patients were 20 mL, 5 mL, and 5 mL. The visual analogue scale pain scores of the three patients were 1, 2, and 2 on postoperative day 1, and were 1, 2, and 1 on postoperative day 3. No perioperative complications, such as bulge, wound infection and hematoma, occurred after the surgery. All of the patients were discharged on the third day after the operation. There was no chronic pain and no hernia recurrence during the follow-up. This study showed that the laparoscopic TAPP approach with the self-gripping mesh is safe and feasible, and can be considered an alternative method for the treatment of bilateral lumbar hernias.

关键词： Bilateral lumbar hernia Laparoscopic repair Transabdominal preperitoneal Self-gripping mesh

Labeled Network Stack: A High-Concurrency and Low-Tail Latency Cloud Server Framework for Massive IoT Devices

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Journal of Computer Science & Technology 2020年第1期35卷 179-193页

作者： Wen-Li Zhang Ke Liu Yi-Fan Shen Ya-Zhu Lan Hui Song ming-yu chen yuan-Fei chen State Key Laboratory of Computer Architecture Institute of Computing TechnologyChinese Academy of Sciences Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China Peng cheng Laboratory Shenzhen 518000China Zhongke Zhicheng Electronic Technology Company Limited Jining 272000China

Internet of Things(IoT)applications have massive client connections to cloud servers,and the number of networked IoT devices is remarkably *** services require both low-tail latency and high concurrency in *** study aims to determine whether an order of magnitude improvement is possible in tail latency and concurrency in mainstream systems by proposing a hardware-software codesigned labeled network stack(LNS)for future *** key innovation is a cross-layered payload labeling mechanism that distinguishes different requests by payload across the full network stack,including application,TCP/IP,and Ethernet *** type of design enables prioritized data packet processing and forwarding along the full datapath,such that latency-insensitive requests cannot significantly interfere with high-priority *** build a prototype datacenter server to evaluate the LNS design against a commercial X86 server and the mTCP research,using a cloud-supported IoT application *** results show that the LNS design can provide an order of magnitude improvement in tail latency and concurrency.A single datacenter server node can support over 2 million concurrent long-living connections for IoT devices as a 99-percentile tail latency of 50 ms is *** addition,the hardware-software codesign approach remarkably reduces the labeling and prioritization overhead and constrains the interference of high-priority requests to low-priority requests.

关键词： tail latency high concurrency network stack cloud server Internet of Things(IoT)service

Reinforcing effect of calcium sulfate cement bovine bone morphogenetic protein on vertebral in the rabbit model of osteoporosis

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Asian Pacific Journal of Tropical Medicine 2014年第5期7卷 382-385页

作者： Jie Zhang chen Sheng-Guo Kaken.Habaerxi Shawuti.Alimujiang yu chen ming-Zhen Peng Rong yue yu-Lian Wu De-Quan Wang yu-ming chen Xinjiang Autonomous Region People's Hospital Anatomy Section Xinjiang Medical University Otolaryngology Xinjiang Medical University

Objective:To observe reinforcing effect of calcium sulfate cement(CSC) bovine bone morphogenetic protein(bBMP) on vertebral in the rabbit model of ***:A total of 48 New Zealand white rabbits were randomly divided into group Ⅰ(blank control group),groupⅡ(CSC injection group),group Ⅲ(CSC/bBMP injection group) and control *** rabbit osteoporosis model was established rapidly by using castration mcthod+methylprcdnisolone *** modeling,groups Ⅱ.Ⅲ were given corresponding vertebral body injection material,and 4 animals were sacrificed respectively at 24 h,6 weeks,12 weeks after vertebral *** pathological status,vertebral mineral density and vertebral body bone mechanical strength were ***:Vertebral body structure form was normal in the groups Ⅱand Ⅲ.Trabecular bone coarsens,connection and repair were observed in micro fracture and bone defects,bone trabecular connectivity was superior to group I significantly;vertebral body compression strength in the group I was on the decline,vertebral compression strength in the groups Ⅱ and Ⅲ was on the rise,the largest *** BMC and BMD in groups Ⅱand Ⅲ were incresed,and significantly higher than group I after 6 weeks(P<0.05),BMC and BMD in group Ⅲ after 12 weeks were higher than the other three ***:Compound bBMP CSC has good bone *** can improve the three-dimensional construction effect for osteoporosis vertebral trabecula,and can significantly improve the vertebral strength,as a vertebral packing material with good application prospect.

关键词： CSC BBMP Rabbit Osteoporosis Vertebral reinforcing

IMPULP:A Hardware Approach for In-Process Memory Protection via User-Level Partitioning

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Journal of Computer Science & Technology 2020年第2期35卷 418-432页

作者： Yang-Yang Zhao ming-yu chen yu-Hang Liu Zong-Hao Yang Xiao-Jing Zhu Zong-Hui Hong yun-Ge Guo State Key Laboratory of Computer Architecture Institute of Computing TechnologyChinese Academy of Sciences Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China Peng cheng Laboratory Shenzhen 518055China

In recent years many security attacks occur when malicious codes abuse in-process memory *** to the increasing complexity,an application program may call third-party code which cannot be controlled by programmers but may contain security *** a result,the users have the risk of suffering information leakage and control flow ***,current solutions like Intel memory protection extensions(MPX)severely degrade performance,while other approaches like Intel memory protection keys(MPK)lack flexibility in dividing security *** this paper,we propose IMPULP,an effective and efficient hardware approach for in-process memory *** rationale of IMPULP is user-level partitioning that user code segments are divided into different security domains according to their instruction addresses,and accessible memory spaces are specified dynamically for each domain via a set of boundary *** instruction related to memory access will be checked according to its security domain and the corresponding boundaries,and illegal in-process memory access of untrusted code segments will be *** can be leveraged to prevent a wide range of in-process memory abuse attacks,such as buffer overflows and memory *** verification,an FPGA prototype based on RISC-V instruction set architecture has been *** present eight tests to verify the effectiveness of IMPULP,including five memory protection function tests,a test to defense typical buffer overflow,a test to defense famous memory leakage attack named Heartbleed,and a test for security *** execute the SPEC CPU2006 benchmark programs to evaluate the efficiency of *** performance overhead of IMPULP is less than 0.2%runtime on average,which is ***,the resource overhead is less than 5.5%for hardware modification of IMPULP.

关键词： in-process isolation memory protection out-of-bounds user-level partitioning

Blow-up for Doubly Degenerate Nonlinear Parabolic Equations

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Acta Mathematica Sinica,English Series 2008年第9期24卷 1525-1532页

作者： ming yu chen School of Science,Quanzhou Nomal University,Quanzhou,Fujian 362000,P,R.China School of Science Quanzhou Nomal University Quanzhou P. R. China

In this paper, we give a complete picture of the blow-up criteria for weak solutions of the Dirichlet problem of some doubly degenerate nonlinear parabolic equations.

关键词： doubly degenerate parabolic equation weak solution blow up global existence first eigenvalue

A new angelol-type coumarin glucoside from Angelica pubescens

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Chinese Chemical Letters 2008年第10期19卷 1237-1239页

作者： Xi Fei Ding Xu Feng yun Fa Dong Xing Zeng Zhao yu chen ming Wang Jiangsu Center for Research ＆ Development of Medicinal Plants Jiangsu Institute of Botany China Academic of Science Nanfing Botanical GaMen Mere. Sun Yat-Sen Nanfing 210014 China

A new angelol-type coumarin glucoside, 6-[（1R,2R）-1, 2-dihydroxy-3-β-D-glucosyloxy-3-methylbutyl]-7-methoxycoumarin, was isolated from the roots of Angelica pubescens. Its structure was elucidated on the basis of s... 详细信息

关键词： Angelica pubescens UmbeUiferae Coumarin glucoside 6-[(1R,2R)-1,2-Dihydroxy-3-β-D-glucosyloxy-3-methylbutyl]-7-methoxy-coumarin