检索结果-南通市图书馆

Efficient Activity Enhancement of a Lipase from Sporisorium reilianum for the Synthesis of a Moxifloxacin Chiral Intermediate via Rational Design

引用

Engineering 2022年第12期19卷 207-216页

作者： Xue Cai jiang-wei shen Yu Qiang Jing Hua Zhang-Qi Ma Zhi-Qiang Liu Yu-Guo Zheng The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals Zhejiang University of TechnologyHangzhou 310014China Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and BioengineeringZhejiang University of TechnologyHangzhou 310014China

Lipase-catalyzed stereoselective resolution of cis-(±)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate(cis-(±)-1)is an attractive route for the synthesis of(S,S)-2,8-diazobicyclo[4.3.0]nonane,an important chiral intermediate of the fluoroquinolone antibiotic,*** our previous study,a lipase from Sporisorium reilianum(SRL)was identified to possess excellent thermostability and pH ***,the low enzymatic activity of the SRL is a challenge that must be addressed.A rational design was initially employed for SRL tailoring according to the engineered Candida antarctica lipase B(CALB),resulting in a beneficial variant called SRL-I194N/***,two key amino acid residues in loop 6,L145 and L154,which might modulate the lid conformation between open and closed,were identified.A tetra-site variant,SRL-I194N/V195L/L145V/L154G(V13),with a significantly enhanced activity of 87.8 U∙mg^(−1) was obtained;this value was 2195-fold higher than that of wild-type *** V13 was used to prepare optically pure(2S,3R)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate((2S,3R)-1),resolving 1 mol∙L^(−1) cis-(±)-1 with a conversion of 49.9%in 2 h and absolute stereoselectivity(E>200).Excellent stability with a half-life of 92.5 h was also observed at 50℃.Overall,the study findings reveal a lipase with high activity toward cis-(±)-1 at an industrial level and may offer a general strategy for enhancing the enzyme activity of other lipases and other classes of enzymes with a lid moiety.

关键词： Lipase Sporisorium reilianum Site-directed mutagenesis Molecular dynamics simulation Rational design Moxifloxacin

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Analysis of Sea Surface Temperature Cooling in Typhoon Events Passing the Kuroshio Current

引用

Journal of Ocean University of China 2024年第2期23卷 287-303页

作者： HU Yuyi SHAO weizeng shen wei ZUO Juncheng jiang Tao HU Song College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China East China Sea Environment Monitoring Ministry of Natural ResourcesShanghai 201206China China Waterborne Transport Research Institute Ministry of TransportBeijing 100088China

The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately *** water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model ***,the RMSE of the SST is 0.92℃ with a COR of approximately *** revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively *** variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak ***,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio *** sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the *** variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in ***,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.

关键词： typhoon wave sea surface temperature Kuroshio Current

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhancing the electrocatalytic performance of nitrate reduction to ammonia by in-situ nitrogen leaching

引用

Chinese Chemical Letters 2024年第2期35卷 564-569页

作者： Mimi Fu Yini Mao Hua Wang wei Luo Yimin jiang wei shen Ming Li Rongxing He College of Chemistry and Chemical Engineering Southwest UniversityChongqing 400715China

Electrochemical nitrate reduction reaction (NITRR) is regarded as a “two birds-one stone” method for the treatment of nitrate contaminant in polluted water and the synthesis of valuable ammonia, which is retarded by the lack of highly reactive and selective electrocatalysts .Herein, for the first time, nickel foam supported Co_(4) N was designed as a high-performance NITRR catalyst by an in-situ nonmetal leaching-induced *** the optimal potential, the Co_(4) N/NF catalyst achieves ultra-high Faraday efficiency and NH_(3) selectivity of 95.4% and 99.4%, *** situ X-ray absorption spectroscopy (XAS), together with other experiments powerfully reveal that the nitrogen vacancies produced by nitrogen leaching are stable and play a key role in boosting nitrate reduction to *** calculations confirm that Co_(4) N with abundant nitrogen vacancies can optimize the adsorption energies of NO_(3)^(-) and intermediates, lower the free energy (Δ G ) of the potential-determining step (*NH_(3) to NH_(3) ) and inhibit the formation of N-containing *** addition, we also conclude that the nitrogen vacancies can stabilize the adsorbed hydrogen, making H_(2) quite difficult to produce, and lowering ΔG from *NO to *NOH, which facilitates the selective reduction of *** study reveals significant insights about the in-situ nonmetal leaching to enhance the NITRR activity.

关键词： Co4N Nitrate reduction In-situ nonmetal leaching Nitrogen vacancy Mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Wireless multisite sensing systems for continuous physiological monitoring

引用

Science China Materials 2024年第6期67卷 2045-2047页

作者： Ruilai wei Qilin Hua Guozhen shen School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China Institute of Flexible Electronics Beijing Institute of TechnologyBeijing 102488China

Respiratory diseases rank as the third leading cause of adult mortality[1],while cardiopulmonary and gastrointestinal issues are the primary cause of death within the first five years of a child’s life[2].The monitoring of cardiac,respiratory,and gastrointestinal sounds plays a vital role in routine care,as alterations or absence of these body sounds can serve as indicators of underlying diseases.

关键词： routine continuous monitoring

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

引用

Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： Li Yuchun shen Chao Liu wei Li Dong Department of Hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this *** auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on *** parametric vibration equation is established for the test model using the finite-element *** auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent *** effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test *** with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental *** a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric *** with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

引用

CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao shen wei Gu Wanxing sheng Keyan Liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Coupled simulation of fluid-particle interaction for large complex granules:A resolved CFD-DEM method for modelling the airflow in a vertical fixed bed of irregular sinter particles

引用

Particuology 2024年第7期90卷 292-306页

作者： Chengzhi Li Yu Zhang Jiahe shen wei Zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China School of Transportation and Logistics Engineering Wuhan University of TechnologyWuhan 430063China Centre for Bulk Solids and Particulate Technologies The University of NewcastleCallaghan NSW 2308Australia

A resolved CFD-DEM method is proposed to simulate the fluid-particle interaction for large complex *** airflow in a vertical sinter fixed bed is numerically studied using this *** multi-sphere clumped method is used to create irregular sinter particles in *** immersed boundary method and dynamic cell refinement are applied to describe the fluid flow around particles with higher resolution,by which the fluid-particle interaction can be simulated more *** simulation results presented the packing voidage distributions and the airflow fields in the sinter beds of different single and mixed particle size *** bed pressure drops were simulated and the results were compared with the corresponding experimental *** good agreement indicated that the proposed resolved CFD-DEM method is an effective tool to model the fluid-particle interaction for irregular large granules in the gas-solid multi-phase systems.

关键词： Resolved CFD-DEM method Irregular sinter particles Multi-sphere clumped method Immersed boundary method Dynamic cell refinement

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Bone cement enhanced pedicle screw fixation combined with vertebroplasty for elderly patients with malignant spinal tumors

引用

Chinese Medical Journal 2013年第13期126卷 2495-2498页

作者： TAN jiang-wei shen Bing-hua DU wei LIU jiang-qing LU Shi-qiao Department of Spinal Surgery Yantaishan Hospital Yantai Shandong 264008 China

Background Older patients with malignant spinal tumors are difficult to treat because they have many co-morbidities including osteoporosis. The purpose of this research is to discuss the technique and clinical outcome of bone cement enhanced pedicle screw fixation combined with vertebroplasty （the Sandwich Procedure） for elderly patients with severe osteoporosis and malignant spinal tumors. Methods This study includes 28 consecutive elderly patients with malignant thoracic or lumbar spinal tumors. There were nine patients with myelomas, and 19 patients with metastatic bone tumors. The Sandwich Procedure began with curettage of the tumor and a vertebroplasty with bone cement （polymethyl methacrylate, PMMA）, followed by PMMA enhanced pedicle screw fixation. Patients were evaluated with the visual analogue scale （VAS）, oswestry disability index （ODI）, American Spinal Cord Injury Association （ASIA） neurological function classification, and the radiographic degree of kyphosis （Cobb angle）. Data were analyzed using paired t-test to compare the pre- and post-operative values. The complications, local recurrences, and the survival status were also recorded. Results There was no operative mortality, and the mean operative time was 210 minutes （range 150-250 minutes）. The average blood loss was 1550 ml （range 650-3300 ml）. The average amount of cement for vertebroplasty was 3.6 ml （range 3-5 ml）. The VAS, ODI, and ASIA scores were significantly improved after surgery （P 〈0.05）. However, we found no differences between the pre and post-operative Cobb angles. The shortest survival time was 3 months, and we found no evidence of local recurrence in this group of patients. Conclusion The Sandwich Procedure is a safe operation and provides symptomatic relief in these difficult patients, permitting further treatment with chemotherapy or radiotherapy.

关键词： Sandwich procedure, malignant spinal tumor, osteoporosis bone cement, pedicle screw

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Decadal length-of-day and geomagnetic changes imply more complex Earth’s core motions

引用

Science Bulletin 2024年第13期69卷 2038-2041页

作者： Hao Ding Jiancheng Li weiping jiang Wenbin shen School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China GNSS Research Center Wuhan UniversityWuhan 430079China

Since the 1950s,the length-of-day variations(DLOD)of the Earth’s rotation have received extensive attention and research in various fields,including geodynamics,geomagnetism,geodesy,seismology,geology,marine science,environmental science,and even biology and *** the abundance of related studies and notable advancements,the underlying mechanism behind the decadal changes in DLOD remains a persistent unresolved *** essential aspect of investigating this issue lies in its potential to unveil the Earth’s core motions[1,2].Despite the presence of various hypothesized and constructed models about the Earth’s core motions,these models typically exhibit simplicity.

关键词： Earth geology geomagnetic

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Data-Driven Learning Control Algorithms for Unachievable Tracking Problems

引用

IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 205-218页

作者： Zeyi Zhang Hao jiang Dong shen Samer S.Saab the School of Mathematics Renmin University of ChinaBeijing 100872China IEEE the School of Engineering Lebanese American UniversityByblos 2038Lebanon

For unachievable tracking problems, where the system output cannot precisely track a given reference, achieving the best possible approximation for the reference trajectory becomes the objective. This study aims to investigate solutions using the Ptype learning control scheme. Initially, we demonstrate the necessity of gradient information for achieving the best ***, we propose an input-output-driven learning gain design to handle the imprecise gradients of a class of uncertain systems. However, it is discovered that the desired performance may not be attainable when faced with incomplete *** address this issue, an extended iterative learning control scheme is introduced. In this scheme, the tracking errors are modified through output data sampling, which incorporates lowmemory footprints and offers flexibility in learning gain *** input sequence is shown to converge towards the desired input, resulting in an output that is closest to the given reference in the least square sense. Numerical simulations are provided to validate the theoretical findings.

关键词： Data-driven algorithms incomplete information iterative learning control gradient information unachievable problems

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：