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参数估计 2

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Properties and catalytic mechanism of -glutamyltranspeptidase from NX-2

WANG Qian, YAO Zhong, XUN Zhijing, XU Xiaoying, XU Hong, WEI Ping

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 456-461 doi: 10.1007/s11705-008-0075-3

摘要: Since -glutamyltranspeptidase (GGT) especially catalyses the transfer of the -glutamyl moiety to a variety of amino acids and short peptides, GGT has important practical value for enzymatic synthesis of -glutamyl compounds. In this paper, the GGT produced from NX-2 was purified by a combination of ammonium sulfate fractionation and ion exchange chromatography, and the properties of purified GGT were investigated. At the conditions of pH 10.0, D-glutamine (D-Gln)/L-tryptophan (L-Trp) with a molar ratio of 5 : 7, a temperature 40°C and a reaction time of 4 h, a higher conversion rate of 42% was obtained. According to the time course, the catalytic mechanism of enzymatic synthesis of -D-glutamyl-L-tryptophan (-D-Gln-L-Trp) was discussed. It was demonstrated that the GGT can catalyze not only the reaction of transpeptidation, but also the irreversible hydrolysis of the products which results in the decrease of the yield of the products. The affinity parameter of GGT to D-Gln (Km) was 5.08 mmol·L and the maximum reaction rate of transpeptidation () was determined as 0.034 mmol·min·L, while the affinity parameter of GGT to -D-Gln-L-Trp (’) was 2.267 mmol·L, and the maximum reaction rate of hydrolysis (’) was 0.012 mmol·min·L.

关键词: catalytic mechanism     mmol·min·L     D-glutamine     affinity parameter     important practical    

High-affinity T cell receptors redirect cytokine-activated T cells (CAT) to kill cancer cells

Synat Kang, Yanyan Li, Yifeng Bao, Yi Li

《医学前沿(英文)》 2019年 第13卷 第1期   页码 69-82 doi: 10.1007/s11684-018-0677-1

摘要:

Cytokine-activated T cells (CATs) can be easily expanded and are widely applied to cancer immunotherapy. However, the good efficacy of CATs is rarely reported in clinical applications because CATs have no or very low antigen specificity. The low-efficacy problem can be resolved using T cell antigen receptor-engineered CAT (TCR-CAT). Herein, we demonstrate that NY-ESO-1157–165 HLA-A*02:01-specific high-affinity TCR (HAT)-transduced CATs can specifically kill cancer cells with good efficacy. With low micromolar range dissociation equilibrium constants, HAT-transduced CATs showed good specificity with no off-target killing. Furthermore, the high-affinity TCR-CATs delivered significantly better activation and cytotoxicity than the equivalent TCR-engineered T cells (TCR-Ts) in terms of interferon-g and granzyme B production and in vitro cancer cell killing ability. TCR-CAT may be a very good alternative to the expensive TCR-T, which is considered an effective personalized cyto-immunotherapy.

关键词: cytokine-activated T cells     high-affinity T cell receptor     cancer immunotherapy     TCR-CAT    

Atomistic characterization of binding modes and affinity of peptide inhibitors to amyloid-

Fufeng LIU,Wenjie DU,Yan SUN,Jie ZHENG,Xiaoyan DONG

《化学科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 433-444 doi: 10.1007/s11705-014-1454-6

摘要: The aggregation of amyloid -protein (A ) is tightly linked to the pathogenesis of Alzheimer’s disease. Previous studies have found that three peptide inhibitors (i.e., KLVFF, VVIA, and LPFFD) can inhibit A aggregation and alleviate A -induced neurotoxicity. However, atomic details of binding modes and binding affinities between these peptide inhibitors and A have not been revealed. Here, using molecular dynamics simulations and molecular mechanics Poisson Boltzmann surface area (MM/PBSA) analysis, we examined the effect of three peptide inhibitors (KLVFF, VVIA, and LPFFD) on their sequence-specific interactions with A and the molecular basis of their inhibition. All inhibitors exhibit varied binding affinity to A , in which KLVFF has the highest binding affinity, whereas LPFFD has the least. MM/PBSA analysis further revealed that different peptide inhibitors have different modes of interaction with A , consequently hotspot binding residues, and underlying driving forces. Specific residue-based interactions between inhibitors and A were determined and compared for illustrating different binding and inhibition mechanisms. This work provides structure-based binding information for further modification and optimization of these three peptide inhibitors to enhance their binding and inhibitory abilities against A aggregation.

关键词: Alzheimer’s disease     amyloid β-protein     peptide inhibitors     protein-protein interaction     molecular dynamics simulation    

LC/MS/MS and radioisotope method combined for recognizing the affinity between catalpol and OCT2 transporter

Zhiyu ZHANG, Changxiao LIU, Duanyun SI, Rong LU, Xiulin YI

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 436-442 doi: 10.1007/s11705-012-1222-4

摘要: More and more herbal medicines are found to be the substrates of drug transporters. In this paper, chromatography/tandem mass spectrometry (LC/MS/MS) combined with radioisotope method was used for the quantification of catalpol, a traditional Chinese medicine, to study the affinity relationship between herbal medicines and transporters. Catalpol uptake experiment was carried out by using several transporters (OAT1, OCT2, OAT3, OATP1B1 and OATP2B1). And samples were precipitated with methanol and quantified with LC/MS/MS. The results show that catalpol has a good affinity with OCT2-transfected S2 cells. After studying drug-drug interaction between catalpol and C-tetraethylammonium (TEA), we found that catalpol is able to facilitate TEA transport mediated by OCT2, suggesting that catalpol could probably be a new promoter of OCT2.

关键词: catalpol     LC/MS/MS     OCT2    

PtHAK5, a candidate for mediating high-affinity K

Haili YANG, Weidan ZHANG, Weiwei CHAI, Wenying WANG, Li GAO, Jing ZHANG, Yongping WANG, Suo-Min WANG

《农业科学与工程前沿(英文)》 2018年 第5卷 第1期   页码 108-117 doi: 10.15302/J-FASE-2018200

摘要: is a typical salt-exclu-ding halophytic grass with strong salt-tolerance, which enhances tolerance by restricting Na influx as well as having a strong selectivity for K over Na . The HAK5 K transporters generally modulate effective K acquisition in plants, especially under low K condition. In this study, from was isolated by RT-PCR and characterized using yeast complementation. The results showed PtHAK5 consisted of 784 amino acids and shared over 80% homology with the identified high-affinity K transporter HAK5 from other higher plants. The expression of rescued the K -uptake-defective phenotype of yeast strain CY162. In conclusion, PtHAK5 is a candidate for mediating high-affinity K uptake under low K conditions.

关键词: K+ uptake     PtHAK5     Puccinellia tenuiflora     yeast complementation    

煤净化燃烧及伴生物产品化

朱雪芳

《中国工程科学》 1999年 第1卷 第1期   页码 53-57

摘要:

煤净化燃烧及伴生物产品化新工艺,是在电厂燃煤中加特制的掺烧剂共同粉磨产生亲合颗粒,喷入锅炉内进行亲合煅烧。保证供热发电的同时实现降低残炭、提高粉煤灰活性、固结脱硫、降低Nox、CO2,并将全部固态伴生物在具有速烧速冷的燃煤锅炉内直接生成优质水泥熟料;实现基本消除燃烧的全部污染(气体和固体污染),且不产生二次污染,从而达到清洁生产的目的。

关键词: 净化燃烧     伴生物产品化     速烧速冷     固结脱硫     亲合颗料     亲合煅烧    

Processing parameter optimization of fiber laser beam welding using an ensemble of metamodels and MOABC

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0703-5

摘要: In fiber laser beam welding (LBW), the selection of optimal processing parameters is challenging and plays a key role in improving the bead geometry and welding quality. This study proposes a multi-objective optimization framework by combining an ensemble of metamodels (EMs) with the multi-objective artificial bee colony algorithm (MOABC) to identify the optimal welding parameters. An inverse proportional weighting method that considers the leave-one-out prediction error is presented to construct EM, which incorporates the competitive strengths of three metamodels. EM constructs the correlation between processing parameters (laser power, welding speed, and distance defocus) and bead geometries (bead width, depth of penetration, neck width, and neck depth) with average errors of 10.95%, 7.04%, 7.63%, and 8.62%, respectively. On the basis of EM, MOABC is employed to approximate the Pareto front, and verification experiments show that the relative errors are less than 14.67%. Furthermore, the main effect and the interaction effect of processing parameters on bead geometries are studied. Results demonstrate that the proposed EM-MOABC is effective in guiding actual fiber LBW applications.

关键词: laser beam welding     parameter optimization     metamodel     multi-objective    

Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

《结构与土木工程前沿(英文)》 2013年 第7卷 第2期   页码 133-136 doi: 10.1007/s11709-013-0202-1

摘要: This article examines the capability of Gaussian process regression (GPR) for prediction of effective stress parameter ( ) of unsaturated soil. GPR method proceeds by parameterising a covariance function, and then infers the parameters given the data set. Input variables of GPR are net confining pressure ( ), saturated volumetric water content ( ), residual water content ( ), bubbling pressure ( ), suction ( ) and fitting parameter ( ). A comparative study has been carried out between the developed GPR and Artificial Neural Network (ANN) models. A sensitivity analysis has been done to determine the effect of each input parameter on . The developed GPR gives the variance of predicted . The results show that the developed GPR is reliable model for prediction of of unsaturated soil.

关键词: unsaturated soil     effective stress parameter     Gaussian process regression (GPR)     artificial neural network (ANN)     variance    

1000 MW ultra-supercritical turbine steam parameter optimization

FENG Weizhong

《能源前沿(英文)》 2008年 第2卷 第2期   页码 187-193 doi: 10.1007/s11708-008-0030-5

摘要: The 2 × 1000 MW ultra-supercritical steam turbine of Shanghai Waigaoqiao Phase III project, which uses grid frequency regulation and overload control through an overload valve, is manufactured by Shanghai Turbine Company using Siemens technology. Through optimization, the steam pressure is regarded as the criterion between constant pressure and sliding pressure operation. At high circulating water temperature, the turbine overload valve is kept closed when the unit load is lower than 1000 MW while at other circulating water temperatures the turbine can run in sliding pressure operation when the unit load is higher than 1000 MW and the pressure is lower than 27 MPa This increases the unit operation efficiency. The 3D bending technology in the critical piping helps to reduce the project investment and minimize the reheat system pressure drop which improves the unit operation efficiency and safety. By choosing lower circulating water design temperature and by setting the individual Boiler Feedwater Turbine condenser to reduce the exhaust steam flow and the heat load to the main condenser, the unit average back pressure and the terminal temperature difference are minimized. Therefore, the unit heat efficiency is increased.

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要: When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词: fast-steering mirror     structural parameter     PI controller     bandwidth     notch filter    

Energy efficient cutting parameter optimization

Xingzheng CHEN, Congbo LI, Ying TANG, Li LI, Hongcheng LI

《机械工程前沿(英文)》 2021年 第16卷 第2期   页码 221-248 doi: 10.1007/s11465-020-0627-x

摘要: Mechanical manufacturing industry consumes substantial energy with low energy efficiency. Increasing pressures from energy price and environmental directive force mechanical manufacturing industries to implement energy efficient technologies for reducing energy consumption and improving energy efficiency of their machining processes. In a practical machining process, cutting parameters are vital variables set by manufacturers in accordance with machining requirements of workpiece and machining condition. Proper selection of cutting parameters with energy consideration can effectively reduce energy consumption and improve energy efficiency of the machining process. Over the past 10 years, many researchers have been engaged in energy efficient cutting parameter optimization, and a large amount of literature have been published. This paper conducts a comprehensive literature review of current studies on energy efficient cutting parameter optimization to fully understand the recent advances in this research area. The energy consumption characteristics of machining process are analyzed by decomposing total energy consumption into electrical energy consumption of machine tool and embodied energy of cutting tool and cutting fluid. Current studies on energy efficient cutting parameter optimization by using experimental design method and energy models are reviewed in a comprehensive manner. Combined with the current status, future research directions of energy efficient cutting parameter optimization are presented.

关键词: energy efficiency     cutting parameter     optimization     machining process    

Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 367-376 doi: 10.1007/s11465-017-0429-y

摘要:

A new hierarchical parameter estimation method for doubly fed induction generator (DFIG) and drive train system in a wind turbine generator (WTG) is proposed in this paper. Firstly, the parameters of the DFIG and the drive train are estimated locally under different types of disturbances. Secondly, a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results. The main benefit of the proposed scheme is the improved estimation accuracy. Estimation results confirm the applicability of the proposed estimation technique.

关键词: wind turbine generator     DFIG     drive train system     hierarchical parameter estimation method     trajectory sensitivity technique    

Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1082-1094 doi: 10.1007/s11709-019-0537-3

摘要: An out-put only modal parameter identification method based on variational mode decomposition (VMD) is developed for civil structure identifications. The recently developed VMD technique is utilized to decompose the free decay response (FDR) of a structure into to modal responses. A novel procedure is developed to calculate the instantaneous modal frequencies and instantaneous modal damping ratios. The proposed identification method can straightforwardly extract the mode shape vectors using the modal responses extracted from the FDRs at all available sensors on the structure. A series of numerical and experimental case studies are conducted to demonstrate the efficiency and highlight the superiority of the proposed method in modal parameter identification using both free vibration and ambient vibration data. The results of the present method are compared with those of the empirical mode decomposition-based method, and the superiorities of the present method are verified. The proposed method is proved to be efficient and accurate in modal parameter identification for both linear and nonlinear civil structures, including structures with closely spaced modes, sudden modal parameter variation, and amplitude-dependent modal parameters, etc.

关键词: modal parameter identification     variational mode decomposition     civil structure     nonlinear system     closely spaced modes    

Shallow foundation response variability due to soil and model parameter uncertainty

Prishati RAYCHOWDHURY,Sumit JINDAL

《结构与土木工程前沿(英文)》 2014年 第8卷 第3期   页码 237-251 doi: 10.1007/s11709-014-0242-1

摘要: Geotechnical uncertainties may play crucial role in response prediction of a structure with substantial soil-foundation-structure-interaction (SFSI) effects. Since the behavior of a soil-foundation system may significantly alter the response of the structure supported by it, and consequently several design decisions, it is extremely important to identify and characterize the relevant parameters. Moreover, the modeling approach and the parameters required for the modeling are also critically important for the response prediction. The present work intends to investigate the effect of soil and model parameter uncertainty on the response of shallow foundation-structure systems resting on dry dense sand. The SFSI is modeled using a beam-on-nonlinear-winkler-foundation (BNWF) concept, where soil beneath the foundation is assumed to be an assembly of discrete, nonlinear elements composed of springs, dashpots and gap elements. The sensitivity of both soil and model input parameters on shallow foundation responses are investigated using first-order second-moment (FOSM) analysis and Monte Carlo simulation through Latin hypercube sampling technique. It has been observed that the degree of accuracy in predicting the responses of the shallow foundation is highly sensitive soil parameters, such as friction angle, Poisson’s ratio and shear modulus, rather than model parameters, such as stiffness intensity ratio and spring spacing; indicating the importance of proper characterization of soil parameters for reliable soil-foundation response analysis.

关键词: shallow foun dation     sensitivity analysis     centrifuge data     first-order-second-moment (FOSM) method     parameter uncertainty    

Parameter studies on impact in a lap joint

Amir M. RAHMANI,Elizabeth K. ERVIN

《机械工程前沿(英文)》 2015年 第10卷 第1期   页码 64-77 doi: 10.1007/s11465-014-0322-x

摘要:

To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during steady state response, six influential parameters are studied: damping ratio, contact stiffness, intermediate contact position, gap, excitation amplitude and beam height. For all parameters, the system response is highly controlled by modes with two contacting springs. Each parameter’s effect on system response is presented including unstable regions, unique trend behaviours result. Recommendations for structural designers are also noted.

关键词: impact mechanics     contact     joint behaviour     modal analysis     parameter study    

标题 作者 时间 类型 操作

Properties and catalytic mechanism of -glutamyltranspeptidase from NX-2

WANG Qian, YAO Zhong, XUN Zhijing, XU Xiaoying, XU Hong, WEI Ping

期刊论文

High-affinity T cell receptors redirect cytokine-activated T cells (CAT) to kill cancer cells

Synat Kang, Yanyan Li, Yifeng Bao, Yi Li

期刊论文

Atomistic characterization of binding modes and affinity of peptide inhibitors to amyloid-

Fufeng LIU,Wenjie DU,Yan SUN,Jie ZHENG,Xiaoyan DONG

期刊论文

LC/MS/MS and radioisotope method combined for recognizing the affinity between catalpol and OCT2 transporter

Zhiyu ZHANG, Changxiao LIU, Duanyun SI, Rong LU, Xiulin YI

期刊论文

PtHAK5, a candidate for mediating high-affinity K

Haili YANG, Weidan ZHANG, Weiwei CHAI, Wenying WANG, Li GAO, Jing ZHANG, Yongping WANG, Suo-Min WANG

期刊论文

煤净化燃烧及伴生物产品化

朱雪芳

期刊论文

Processing parameter optimization of fiber laser beam welding using an ensemble of metamodels and MOABC

期刊论文

Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

期刊论文

1000 MW ultra-supercritical turbine steam parameter optimization

FENG Weizhong

期刊论文

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

期刊论文

Energy efficient cutting parameter optimization

Xingzheng CHEN, Congbo LI, Ying TANG, Li LI, Hongcheng LI

期刊论文

Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

期刊论文

Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

期刊论文

Shallow foundation response variability due to soil and model parameter uncertainty

Prishati RAYCHOWDHURY,Sumit JINDAL

期刊论文

Parameter studies on impact in a lap joint

Amir M. RAHMANI,Elizabeth K. ERVIN

期刊论文