Identification and Characterization of a New Alkaline Thermolysin-Like Protease, BtsTLP1, from Bacillus thuringiensis Serovar Sichuansis Strain MC28

( Zhenghong Zhang ),( Helong Hao ),( Zhongmei Tang ),( Zhengzheng Zou ),( Keya Zhang ),( Zhiyong Xie ),( Lilia Babe,),Frits Goedegebuur,Xiaogang Gu 한국미생물생명공학회(구 한국산업미생물학회) 2015 Journal of microbiology and biotechnology Vol.25 No.8

Thermolysin and its homologs are a group of metalloproteases that have been widely used in both therapeutic and biotechnological applications. We here report the identification and characterization of a novel thermolysin-like protease, BtsTLP1, from insect pathogen Bacillus thuringiensis serovar Sichuansis strain MC28. BtsTLP1 is extracellularly produced in Bacillus subtilis, and the active protein was purified via successive chromatographic steps. The mature form of BtsTLP1 has a molecule mass of 35.6 kDa as determined by mass spectrometry analyses. The biochemical characterization indicates that BtsTLP1 has an apparent Km value of 1.57 mg/ml for azocasein and is active between 20oC and 80oC. Unlike other reported neutral gram-positive thermolysin homologs with optimal pH around 7, BtsTLP1 exhibits an alkaline pH optimum around 10. The activity of BtsTLP1 is strongly inhibited by EDTA and a group of specific divalent ions, with Zn2+ and Cu2+ showing particular effects in promoting the enzyme autolysis. Furthermore, our data also indicate that BtsTLP1 has potential in cleaning applications.

Extended State Observer Based Adaptive Backstepping Nonsingular Fast Terminal Sliding-mode Control for Robotic Manipulators with Uncertainties

Zhenghong Xu,Xiaohui Yang,Wenjie Zhang,Wei Zhang,Shuang Yang,Siyi Zhou,Peter Xiaoping Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9

This paper proposes a novel robust finite-time tracking control scheme for robotic manipulators with uncertainties and external disturbances. In order to reduce the chattering phenomenon and enhance the robustness of the system, we design a novel extended state observer with filter function for estimating the lumped term of system uncertainties and external disturbances. We adopt the backstepping mechanism to design an adaptive backstepping nonsingular fast terminal sliding mode controller, achieve finite time convergence of the tracking errors while avoiding the singularity problem. An adaptive update law is designed for the switching gain, which further weakens the chattering problem. The finite-time convergence of tracking errors and the stability of the closed-loop system are ensured by the Lyapunov criterion. In comparison with other control methods, numerical simulation on a two-link rigid robot manipulator demonstrates the effectiveness and superiority of the proposed method.

Backstepping Sliding Mode Control Based on Extended State Observer for Robotic Manipulators with LuGre Friction

Zhenghong Xu,Xiaohui Yang,Wenjie Zhang,Wei Zhang,Liufang Zhang,Peter Xiaoping Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.6

In this paper, we propose a backstepping integral nonsingular fast terminal sliding mode control approach based on an extended state observer to the trajectory tracking control of robotic manipulators with LuGre friction. In order to improve convergence speed and tracking precision, an integral fast terminal sliding surface is introduced. An appropriate saturation function is designed in the control input to avoid singularity. An extended state observer is employed to estimate the uncertainties and disturbances, and they are compensated by the control laws, for which the chattering can be effectively eliminated. The backstepping method is used to design the control input of the system to ensure the globally asymptotic stability based on the Lyapunov criterion. In comparison with other control methods, simulation results show effectiveness and superiority of this proposed control scheme.

An Adaptive Fault-tolerant Control Method for Robot Manipulators

Wenjie Zhang,Xiaohui Yang,Zhenghong Xu,Wei Zhang,Li Yang,Xiaoping Liu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

This paper presents a new method for adaptive continuous nonsingular fast terminal sliding mode control (ACNFTSMC) based on a novel structure-improved extended state observer (SIESO) for fault-tolerant control (FTC). In response to the initial peaking phenomenon in traditional ESO (TESO), which can severely degrade the accuracy and stability of the control system, The SIESO is designed to replace TESO to estimate the lump disturbances/faults. Besides, to address the problem of the unknown estimation error of ESO, an adaptive technique is applied to compensate for the observation error in real-time. To guarantee fast convergence and chattering-free, the CNFTSMC method is employed. Afterward, the stability and rapid convergence of the control system is demonstrated using Lyapunov theory. Finally, the simulation results verify the superiority of the proposed control strategy compared to the other existing advanced control techniques.

Acute Toxicity to Peptone Concentrations in the Polychaete Perinereis aibuhitensis under Laboratory Culture

Kang, Kyoung-Ho,Zhang, Litao,Ahn, Sam-Young,Kahng, Hyung-Yeel,Zhang, Zhifeng,Sui, Zhenghong The Korean Society of Fisheries and Aquatic Scienc 2011 Fisheries and Aquatic Sciences Vol.14 No.3

Organic pollution causes eutrophication and dystrophication, which occur when excessive amounts of organic matter enters seawater. Eutrophication can contaminate sediment and harm aquaculture. Polychaeta species have been shown to restore eutrophic sediment. In this study, we used peptone to simulate a eutrophic environment and detect the levels at which eutrophication became toxic to the polychaete Perinereis aibuhitensis. Peptone concentrations were 0, 100, 200, and 500 mg/L. The median lethal concentrations were 950.35 mg/L at 48 h, 340.34 mg/L at 72 h, and 120.22 mg/L at 96 h, which are much higher than those of other aquatic species. Polychaeta species are highly tolerant of eutrophication. During the 15-day long-term experiment, sediment loss on ignition, as well as seawater total organic carbon and total nitrogen all decreased significantly (P<0.05). However, $NH_4^+$ concentration increased with time. Perinereis aibuhitensis slowed the increment of $NH_4^+$ but could not prevent its increase. Our results indicate that this polychaete is helpful in the recovery of seawater and sediment from eutrophication.

Expression, Purification, and Bioactivity of (GLP-1A2G)2-HSA Analogs in Pichia pastoris GS115

Wenfang Dou,Junshang Feng,Xiaomei Zhang,Hongyu Xu,Jinsong Shi,Zhenghong Xu 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.6

We developed (GLP-1A2G)2-HSA (GGH) analogsthat are resistant to degradation and also show high serumglucose-reducing activity in vivo. Five analogs with Nterminalextensions were designed based on the proteinGGH. Next, we constructed recombinant plasmids capableof expressing the five analogs in methylotrophic yeastPichia pastoris GS115. Expression reached 150 mg/L in asmall-scale incubation. Fusion proteins were successfullypurified from the supernatant using ultrafiltration concentration,affinity absorption chromatography, hydrophobicchromatography, ion exchange chromatography and gelfiltration. A single band was observed on SDS-PAGE andthe purity was 97%. Activity test results suggested thatboth A-GGH and G-GGH showed better activity in vitroand that their cAMP levels were significantly increased by10-fold compared to GGH without N-terminal extension. Additionally, A-GGH efficiently enhanced the glucoseloweringeffect, which was maintained after the administrationfor 24 h. A-GGH is a potential drug for treating type 2diabetes.

Effects of echinomycin on endothelin-2 expression and ovulation in immature rats primed with gonadotropins

Zhengchao Wang,Yanqing Wu,Liyun Chen,Qianping Luo,Jisen Zhang,Jiajie Chen,Zimiao Luo,Xiaohong Huang,Yong Cheng,Zhenghong Zhang 생화학분자생물학회 2012 Experimental and molecular medicine Vol.44 No.10

Echinomycin is a small-molecule inhibitor of hypoxia- inducible factor-1 DNA-binding activity, which plays a crucial role in ovarian ovulation in mammalians. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1α-mediated endothelin (ET)-2 expressions contributed to ovarian ovulation in response to human chorionic gonadotropin (hCG) during gonadotropin-induced superuvulation. By real-time RT-PCR analysis, ET-2 mRNA level was found to significantly decrease in the ovaries after chinomycin treatment, while HIF-1α mRNA and protein expression was not obviously changed. Further analysis also showed that these changes of ET-2 mRNA were consistent with HIF-1 activity in the ovaires, which is similar with HIF-1α and ET-2 expression in the granulosa cells with gonadotropin and echinomycin treatments. The results of HIF-1α and ET-2 expression in the granulosa cells transfected with cis-element oligodeoxynucleotide (dsODN) under gonadotropin treatment further indicated HIF-1α directly mediated the transcriptional activation of ET-2 during gonadotropin- induced superuvulation. Taken together, these results demonstrated that HIF-1α-mediated ET-2 transcriptional activation is one of the important mechanisms regulating gonadotropin-induced mammalian ovulatory precess in vivo. Echinomycin is a small-molecule inhibitor of hypoxia- inducible factor-1 DNA-binding activity, which plays a crucial role in ovarian ovulation in mammalians. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1α-mediated endothelin (ET)-2 expressions contributed to ovarian ovulation in response to human chorionic gonadotropin (hCG) during gonadotropin-induced superuvulation. By real-time RT-PCR analysis, ET-2 mRNA level was found to significantly decrease in the ovaries after chinomycin treatment, while HIF-1α mRNA and protein expression was not obviously changed. Further analysis also showed that these changes of ET-2 mRNA were consistent with HIF-1 activity in the ovaires, which is similar with HIF-1α and ET-2 expression in the granulosa cells with gonadotropin and echinomycin treatments. The results of HIF-1α and ET-2 expression in the granulosa cells transfected with cis-element oligodeoxynucleotide (dsODN) under gonadotropin treatment further indicated HIF-1α directly mediated the transcriptional activation of ET-2 during gonadotropin- induced superuvulation. Taken together, these results demonstrated that HIF-1α-mediated ET-2 transcriptional activation is one of the important mechanisms regulating gonadotropin-induced mammalian ovulatory precess in vivo.

Three Dimensional Simulation of Viscoelastic Polymer Melts Flow in a Cast Film Process

Zheng, Hong,Yu, Wei,Zhou, Chixing,Zhang, Hongbin The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.1

Three-dimensional simulation of the cast film process for viscoelastic polymer materials was carried out using the finite element method. The flow between the extrusion die and chill roll was assumed to be steady-state and isothermal and the rheological property of material was characterized by a single-mode PTT model. Gravity and inertial flow were considered in the simulation work, but neglecting die swell at the die exit, surface tension, crystallization, transient disturbance and film sag. Simulation results of the cast film production line were compared with the experimental data on the velocity profiles and neck-in values. Neck-in and edge bead was well predicted and the influence of strain-hardening nature, elasticity of materials and operation conditions on the final film shape was also investigated. It was found that the effect of strain-hardening nature was masked for the material with a very low relaxation time when the single-mode PTT model was adopted. Greater elasticity helped to produce a film with smaller neck-in and less waste edge. When the air gap length was increased, it was predicted that neck-in phenomenon would be promoted as well. Moreover, it was found that ratio of neck-in values under different air gap lengths was approximately equal to that of air gap lengths, which was consistent with experimental evidence.