Double hysteresis loops induced by Mn doping in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics

Meng Jiang,Xuhai Li,Jiliang Zhu,Xiaohong Zhu,Wei Shi,Lihua Li,Dingquan Xiao,Jianguo Zhu 한국물리학회 2010 Current Applied Physics Vol.10 No.2

Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 (PNZT95/5) ceramics with 1 mol% and without Mn doping were prepared via conventional solid state reaction process. X-ray diffraction patterns show that the PNZT95/5 and Mn-doped PNZT95/5 (PNZTM95/5) ceramics, with composition near the boundary of the ferroelectric phase (FE)/antiferroelectric phase (AFE), have a rhombohedral perovskite structure. The ferroelectric behavior of PNZT95/5 ceramics is strongly affected by Mn doping. Without any aging process the PNZTM95/5 ceramics possess double hysteresis loops (P–E loops), whereas the PNZT95/5 ceramics possess normal single hysteresis loops. Due to the defect dipoles formed by effectively negatively charged Mn3+ dopants and positively charged O2- vacancies, the PNZTM95/5 ceramics exhibit the double P–E loops. The defect dipole effect has been proved by investigating the P–E loops under different external fields. As a result, the PNZTM95/5 ceramics become ‘‘hardened”, exhibiting a high mechanical quality factor (1300).

Study on Combustible Classification Method Based on Optimized BP Neural Network

Meng ZHU,Lei ZHAO,Honge REN 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.5

In this paper, combustible classification method based on optimized BP neural network is applied by referring to existing combustible classification method and aiming at the vegetation in the region of Hannuo River in Greater Higgnan Mountains. Combustible classification method based on ground type and stand factor is used according to features of BP neural network model. The results indicate that the classification method proposed in this paper owns high precision and good robustness.

Molecular Modeling and Docking Studies of 3'-Hydroxy-N-methylcoclaurine 4'-O-Methyltransferase from Coptis chinensis

Zhu, Qiankun,Zhu, Mengli,Fan, Gaotao,Zou, Jiaxin,Feng, Peichun,Liu, Zubi,Wang, Wanjun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.1

Coptis chinensis 3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (HOMT), an essential enzyme in the berberine biosynthetic pathway, catalyzes the methylation of 3'-hydroxy-N-methylcoclaurine (HMC) producing reticuline. A 3D model of HOMT was constructed by homology modeling and further subjected to docking with its ligands and molecular dynamics simulations. The 3D structure of HOMT revealed unique structural features which permitted the methylation of HMC. The methylation of HMC was proposed to proceed by deprotonation of the 4'-hydroxyl group via His257 and Asp258 of HOMT, followed by a nucleophilic attack on the SAM-methyl group resulting in reticuline. HOMT showed high substrate specificity for methylation of HMC. The study evidenced that Gly117, Thr312 and Asp258 in HOMT might be the key residues for orienting substrate for specific catalysis.

Dynamic quantitative risk assessment of accidents induced by leakage on offshore platforms using DEMATEL-BN

Meng, Xiangkun,Chen, Guoming,Zhu, Gaogeng,Zhu, Yuan The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

On offshore platforms, oil and gas leaks are apt to be the initial events of major accidents that may result in significant loss of life and property damage. To prevent accidents induced by leakage, it is vital to perform a case-specific and accurate risk assessment. This paper presents an integrated method of Ddynamic Qquantitative Rrisk Aassessment (DQRA)-using the Decision Making Trial and Evaluation Laboratory (DEMATEL)-Bayesian Network (BN)-for evaluation of the system vulnerabilities and prediction of the occurrence probabilities of accidents induced by leakage. In the method, three-level indicators are established to identify factors, events, and subsystems that may lead to leakage, fire, and explosion. The critical indicators that directly influence the evolution of risk are identified using DEMATEL. Then, a sequential model is developed to describe the escalation of initial events using an Event Tree (ET), which is converted into a BN to calculate the posterior probabilities of indicators. Using the newly introduced accident precursor data, the failure probabilities of safety barriers and basic factors, and the occurrence probabilities of different consequences can be updated using the BN. The proposed method overcomes the limitations of traditional methods that cannot effectively utilize the operational data of platforms. This work shows trends of accident risks over time and provides useful information for risk control of floating marine platforms.

Cationic methacrylate copolymers containing primary and tertiary amino side groups: Controlled synthesis via RAFT polymerization, DNA condensation, and in vitro gene transfection

Zhu, Caihong,Jung, Sooyeon,Si, Guoying,Cheng, Ru,Meng, Fenghua,Zhu, Xiulin,Park, Tae Gwan,Zhong, Zhiyuan Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of polymer science Part A, Polymer chemist Vol.48 No.13

<P>A versatile family of cationic methacrylate copolymers containing varying amounts of primary and tertiary amino side groups were synthesized and investigated for in vitro gene transfection. Two different types of methacrylate copolymers, poly(2-(dimethylamino)ethyl methacrylate)/aminoethyl methacrylate [P(DMAEMA/AEMA)] and poly(2-(dimethylamino)ethyl methacrylate)/aminohexyl methacrylate [P(DMAEMA/AHMA)], were obtained by reversible addition-fragmentation chain transfer (RAFT) copolymerization of dimethylaminoethyl methacrylate (DMAEMA) with N-(tert-butoxycarbonyl)aminoethyl methacrylate (Boc-AEMA) or N-(tert-butoxycarbonyl)aminohexyl methacrylate (Boc-AHMA) followed by acid deprotection. Gel permeation chromatography (GPC) measurements revealed that Boc-protected methacrylate copolymers had M<SUB>n</SUB> in the range of 16.1–23.0 kDa and low polydispersities of 1.12–1.26. The copolymer compositions were well controlled by monomer feed ratios. Dynamic light scattering and agarose gel electrophoresis measurements demonstrated that these PDMAEMA copolymers had better DNA condensation than PDMAEMA homopolymer. The polyplexes of these copolymers revealed low cytotoxicity at an N/P ratio of 3/1. The in vitro transfection in COS-7 cells in serum free medium demonstrated significantly enhanced (up to 24-fold) transfection efficiencies of PDMAEMA copolymer polyplexes as compared with PDMAEMA control. In the presence of 10% serum, P(DMAEMA/AEMA) and P(DMAEMA/AHMA) displayed a high transfection activity comparable with or better than 25 kDa PEI. These results suggest that cationic methacrylate copolymers are highly promising for development of safe and efficient nonviral gene transfer agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2869–2877, 2010</P> <B>Graphic Abstract</B> <P>A versatile family of cationic PDMAEMA copolymers containing varying amounts of primary and tertiary amine groups were designed and synthesized by controlled RAFT copolymerization. These novel copolymers showed improved DNA condensation and dramatically enhanced gene transfection as compared with the PDMAEMA homopolymer. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.] <img src='wiley_img_2010/0887624X-2010-48-13-POLA24064-gra001.gif' alt='wiley_img_2010/0887624X-2010-48-13-POLA24064-gra001'> </P>

Biochemistry : PpsA, TufA, and Glutaminase Were Modulated under Yop Secretion Conditions in Yersinia enterocolitica

Ling Zhu Meng,Seung Hwan Yang,Tae Jong Kim,Joo Won Suh 한국응용생명화학회 2010 Applied Biological Chemistry (Appl Biol Chem) Vol.53 No.5

Yersinia enterocolitica expresses the Ysc type III secretion system (TTSS) for delivery of effector proteins (Yops) to host cells to manipulate immune system of the host. The study on the physiological change of Y. enterocolitica is important in determinin

Molecular Modeling and Docking Studies of 3'-Hydroxy-N-methylcoclaurine 4'-O-Methyltransferase from Coptis chinensis

Qiankun Zhu,Mengli Zhu,Gaotao Fan,Jiaxin Zou,Peichun Feng,Zubi Liu,Wanjun Wang 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.1

Coptis chinensis 3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (HOMT), an essential enzyme in the berberine biosynthetic pathway, catalyzes the methylation of 3'-hydroxy-N-methylcoclaurine (HMC) producing reticuline. A 3D model of HOMT was constructed by homology modeling and further subjected to docking with its ligands and molecular dynamics simulations. The 3D structure of HOMT revealed unique structural features which permitted the methylation of HMC. The methylation of HMC was proposed to proceed by deprotonation of the 4'-hydroxyl group via His257 and Asp258 of HOMT, followed by a nucleophilic attack on the SAM-methyl group resulting in reticuline. HOMT showed high substrate specificity for methylation of HMC. The study evidenced that Gly117, Thr312 and Asp258 in HOMT might be the key residues for orienting substrate for specific catalysis.

Dynamic quantitative risk assessment of accidents induced by leakage on offshore platforms using DEMATEL-BN

Xiangkun Meng,Guoming Chen,Gaogeng Zhu,Yuan Zhu 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

On offshore platforms, oil and gas leaks are apt to be the initial events of major accidents that may result in significant loss of life and property damage. To prevent accidents induced by leakage, it is vital to perform a case-specific and accurate risk assessment. This paper presents an integrated method of Ddynamic Qquantitative Rrisk Aassessment (DQRA)dusing the Decision Making Trial and Evaluation Laboratory (DEMATEL)-Bayesian Network (BN)dfor evaluation of the system vulnerabilities and prediction of the occurrence probabilities of accidents induced by leakage. In the method, three-level indicators are established to identify factors, events, and subsystems that may lead to leakage, fire, and explosion. The critical indicators that directly influence the evolution of risk are identified using DEMATEL. Then, a sequential model is developed to describe the escalation of initial events using an Event Tree (ET), which is converted into a BN to calculate the posterior probabilities of indicators. Using the newly introduced accident precursor data, the failure probabilities of safety barriers and basic factors, and the occurrence probabilities of different consequences can be updated using the BN. The proposed method overcomes the limitations of traditional methods that cannot effectively utilize the operational data of platforms. This work shows trends of accident risks over time and provides useful information for risk control of floating marine platforms.

Adsorption of copper on iminodisuccinic acid modified attapulgite: characterization and mechanism

Qiuzi Zhu,Jianzhong Zhu,Meng Su,Liang Liu,Cunshi Wang,Dongliang Ji,Wangjun Bai,Wentao Shen 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4

Heavy-metal ions are common pollutants in wastewater and are thus attracting considerable attention. Herein, an eco-friendly biodegradable adsorbent, iminodisuccinic acid (IDS) modified attapulgite (ATP) is prepared by graft-polymerization to reduce Cu(II) in water, referred as IDS-ATP. The equilibrium adsorption capacity of IDS-ATP for Cu(II) is increased by 329.5% and 272% compared with raw ATP and non-degradable chelator ethylenediaminetetraacetic acid-modified ATP (EDTA-ATP), respectively. Moreover, the adsorption capacities for Cu(II) in combined system increased by 186% compared with in single system. The structure and surface properties of IDS-ATP are characterized, demonstrating that the IDS moieties are anchored on the surface of ATP without structural damage. In the aqueous Cu(II) (64 mg /L), the best adsorption pH is 5.0, the best dosage is 800 mg/L, and the adsorption equilibrium time is 4 h. The adsorption of IDS-ATP is chemical adsorption and regenerated adsorbent still exhibits high adsorption capacity. The adsorption mechanism includes the coordination of amino groups with Cu(II), the chelation of -COOH on heavy metals (HMs), and the ion exchange. Taking Cu(II) as an example to study the process of IDS-ATP in water, it is beneficial to apply this degradable material to reduce the other HMs.

The Split-Permeation Grouting Mechanism of Loose and Broken Coal Rock Masses considering the Temporal and Spatial Characteristics of Slurry Viscosity

Hexuan Zhu,Lijun Han,Qingbin Meng,Jun Liu,Lingdong Meng,Wenlong Dong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

Quick-setting grout has time-varying characteristics, and the space porosity of the injected medium changes after being grouted. The above two points need to be considered when loose and broken coal rock masses are grouted with rapid-setting grout. In other words, the coupling effect of the slurry-coal rock mass causes the slurry to exhibit the temporal and spatial characteristics of slurry viscosity (TSCSV). Based on the Bingham fluid constitutive model, a capillary group model with a linear increase in diameter was created, and a one-dimensional penetration grout diffusion model was established considering the TSCSV. The one-dimensional visualization splitting-permeation grout diffusion simulation test system was designed to obtain the space porosity of the broken coal rock mass under different final grouting pressures to obtain the law of the changes in grouting pressure and diffusion height with time under the condition of a fixed grouting rate. Furthermore, the mechanism of splitting-permeation grouting in loose and broken coal rock masses is analysed in depth considering the TSCSV. The results showed that the space porosity of coal rock masses increases linearly. In addition, the calculated value of the slurry diffusion distance was 0.93 − 1.1 times the experimental value considering the TSCSV. The calculated value was in good agreement with the experimental value. The calculated value of the final pressure of orifice grouting was approximately 1.5 times the test value without considering the unevenness of the space porosity distribution (USPD). The grouting pressure was overestimated without considering the USPD. Therefore, the TSCSV of the quick-setting slurry should be fully considered in the grouting design.