检索结果-南通市图书馆

Novel switchable ECF sigma factor transcription system for improving thaxtomin A production in Streptomyces

在线全文

学校读者我要写书评

暂无评论

Synthetic and Systems Biotechnology 2022年第3期7卷 972-981页

作者： Xuejin Zhao Weijia Wei Yeqing Zong Chaoxian Bai Xian Guo hua Zhu Chunbo lou State Key Laboratory of Microbial Resources CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China CAS Key Laboratory of Pathogen Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing100101China Center for Cell and Gene Circuit Design CAS Key Laboratory of Quantitative Engineering BiologyGuangdong Provincial Key Laboratory of Synthetic GenomicsShenzhen Key Laboratory of Synthetic GenomicsShenzhen Institute of Synthetic BiologyShenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen518055China College of Life Sciences University of Chinese Academy of SciencesBeijing100149China

The application of the valuable natural product thaxtomin A,a potent bioherbicide from the potato scab pathogenic Streptomyces strains,has been greatly hindered by the low yields from its native ***,we developed an orthogonal transcription system,leveraging extra-cytoplasmic function(ECF)sigma(σ)factor 17(ECF17)and its cognate promoter Pecf17,to express the thaxtomin gene cluster and improve the production of thaxtomin *** minimal Pecf17 promoter was determined,and a Pecf17 promoter library with a wide range of strengths was ***,a cumate inducible system was developed for precise temporal control of the ECF17 transcription system in *** ***,the switchable ECF17 transcription system could reduce the unwanted influences from host and alleviate the burdens introduced by overexpression of heterologous *** yield of thaxtomin A was significantly improved to 202.1±15.3μg/mL using the switchable ECF17 transcription system for heterologous expression of the thaxtomin gene cluster in *** ***,the applicability of this transcription system was also tested in Streptomyces albus J1074,and the titer of thaxtomin A was raised to as high as 239.3±30.6μg/***,the inducible ECF17 transcription system could serve as a complement of the generally used transcription systems based on strong native constitutive promoters and housekeepingσfactors for the heterologous expression of valuable products in diverse Streptomyces hosts.

关键词： Streptomyces ECF17 sigma factor Heterologous expression Thaxtomin A Transcription system

Nesting season,nest age,and disturbance,but not habitat characteristics,affect nest survival of Chinese grouse

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zoology 2020年第1期66卷 29-37页

作者： Jin-Ming ZHAO Chen YANG Ying-Qiang lou Mei SHI Yun FANG Yue-hua SUN Key Laboratory of Animal Ecology and Conservation Biology Institute of ZoologyChinese Academy of SciencesBeijing100101China School of Life Science Huaibei Normal UniversityHuaibei235000China Chengdu Institute of Biology Chinese Academy of SciencesChengdu610041China

Nest survival is a vital component of breeding success,and affects population dynamics,as the loss of nests is the main cause of reproductive failure in *** identify key factors for the conservation of Chinese grouse Tetrastes sewerzowi,we tested the effects of nest concealment,nest age,nesting season,and habitat edge on nest daily survival rate(DSR)of Chinese grouse using 54 nests found at Lianhuashan Nature Reserve,Gansu,China,***,we controlled for the effect of research activity by testing the effect of nest checks on ***,mammal predation caused 93%of nest *** was 0.986±0.0038 in the constant model and the probability of a nest with a full clutch of 6 eggs surviving the entire 40-day nesting period was 0.526±*** decreased with nest age and nesting season(from 19 May to 3 July).Mammals instead of avian predators being responsible for most nest failures suggest that nest sites might be selected to avoid visual avian predators,but not olfactory mammalian predators,and the decreasing trend of DSR with nest age and nesting season could attribute to an additive exposure ***,nest checks conducted by investigators significantly lowered nest DSR,especially during the late period of nesting season and for older *** predators might locate the nest site by following the investigator's *** on our results,we suggest that the late incubation stage is a particularly vulnerable period for nest survival of Chinese grouse and those researchers should adjust their activities around nests to balance the need of acquiring accurate data and decreasing nest predation risk.

关键词： nest age nest check nesting season nest survival program MARK Tetrastes sewerzowi

高强导电Cu-3Ti-0.1Mg-0.05B-0.05La合金的微观组织与性能

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

工程科学学报 2023年第2期45卷 295-300页

作者：王虎莫永达娄花芬中国铜业工程技术研究院北京102209 昆明冶金研究院有限公司北京分公司北京102209 中铝科学技术研究院有限公司北京102209

采用真空熔铸和冷开坯工艺,通过优化形变热处理工艺,调控基体晶粒尺寸、第二相的析出及分布状态,制备出综合性能优异的Cu-3Ti-0.1Mg-0.05B-0.05La合金.结果表明,经过400℃/2 h一次时效处理后,Cu-3Ti-0.1Mg-0.05B-0.05La合金的显微硬度可... 详细信息

采用真空熔铸和冷开坯工艺,通过优化形变热处理工艺,调控基体晶粒尺寸、第二相的析出及分布状态,制备出综合性能优异的Cu-3Ti-0.1Mg-0.05B-0.05La合金.结果表明,经过400℃/2 h一次时效处理后,Cu-3Ti-0.1Mg-0.05B-0.05La合金的显微硬度可达356 HV,此时导电率为14.5%IACS.透射电镜分析表明,Cu-3Ti-0.1Mg-0.05B-0.05La合金第二相的析出演变规律为富Ti相→颗粒状β′-Cu_(4)Ti相→颗粒状β′-Cu_(4)Ti相+片层状β-Cu_(4)Ti相→片层状β-Cu_(4)Ti相,其中颗粒状β′-Cu_(4)Ti相是最重要的强化相,片层状β-Cu_(4)Ti相会导致合金强度下降,但可以提高导电率.采用二次时效能够进一步优化Cu-3Ti-0.1Mg-0.05B-0.05La合金的综合性能,在合金强度基本不变的条件下,显著提升了合金的导电率.450℃/8 h一次时效+50%冷轧+400℃/1 h二次时效处理后合金的显微硬度和导电率分别达到了341 HV和20.5%IACS.

关键词： Cu-3Ti-0.1Mg-0.05B-0.05La合金微观组织超细晶强化相显微硬度导电率二次时效

Ren-integrable and ren-symmetric integrable systems

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第3期76卷 62-69页

作者： S Y lou School of Physical Science and Technology Ningbo UniversityNingbo315211China

A new type of symmetry,ren-symmetry,describing anyon physics and corresponding topological physics,is ***-symmetry is a generalization of super-symmetry which is widely applied in super-symmetric physics such as super-symmetric quantum mechanics,super-symmetric gravity,super-symmetric string theory,super-symmetric integrable systems and so *** and Grassmann numbers are,in some sense,dual conceptions,and it turns out that these conceptions coincide for the ren situation,that is,a similar conception of ren-number(R-number)is devised for *** particular,some basic results of the R-number and ren-symmetry are exposed which allow one to derive,in principle,some new types of integrable systems including ren-integrable models and ren-symmetric integrable *** examples of ren-integrable KdV-type systems and ren-symmetric KdV equations are explicitly given.

关键词： symmetries integrable systems anyon physics extended supersymmetry ren-symmetry

Colonic metastasis after resection of primary squamous cell carcinoma of the lung:A case report and literature review

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第19期20卷 5930-5934页

作者： Hai-Zhou lou Chun-hua Wang Hong-Ming Pan Qin Pan Jin Wang Department of Medical Oncology Sir Run Run Shaw HospitalCollege of MedicineZhejiang University Bachelor of nursing Department of AdmissionHangzhou Xiasha Hospital Department of Pathology Sir Run Run Shaw HospitalCollege of MedicineZhejiang University

Lung cancer is a common malignancy in the world; however symptomatic colonic metastasis from primary lung cancer is rare. A 64-year-old man was originally found poorly differentiated squamous cell carcinoma of right lung and received right lower lobectomy and lymph node dissection. Three years later, the patient presented to our emergency room with the symptom of upper abdominal pain and weight loss. Abdominal palpation and computed tomography scan of the abdomen revealed a large mass measuring 7.6 cm × 8.5 cm in the ascending colon. Colonoscopy and biopsy revealed poorly differentiated squamous cell carcinoma with similar morphological pattern to that of the previous lung cancer. Chemotherapy was given and the patient died 5 mo later. Lung cancer metastatic to the colon confers a poor prognosis: overall survival ranged from 5 wk to 1 year, with a median survival of 3 mo after the diagnosis of the colonic metastasis.

关键词： Lung neoplasm Colonic metastasis Squamous cell carcinoma Chemotherapy

Combination of methylprednisolone and rosiglitazone promotes recovery of neurological function after spinal cord injury

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2016年第10期11卷 1678-1684页

作者： Xi-gong Li Xiang-jin Lin Jun-hua Du San-zhong Xu Xian-feng lou Zhong Chen Department of Orthopedic Surgery First Affiliated Hospital School of Medicine Zhejiang University

Methylprednisolone exhibits anti-inflammatory antioxidant properties, and rosiglitazone acts as an anti-inflammatory and antioxidant by activating peroxisome proliferator-activated receptor-y in the spinal cord. Methylprednisolone and rosiglitazone have been clinically used during the early stages of secondary spinal cord injury. Because of the complexity and diversity of the inflammatory process after spinal cord injury, a single drug cannot completely inhibit inflammation. Therefore, we assumed that a combination of methylprednisolone and rosiglitazone might promote recovery of neurological function after secondary spinal cord injury. In this study, rats were intraperitoneally rejected with methylprednisolone （30 mg/kg） and rosiglitazone （2 mg/kg） at 1 hour after injury, and methylprednisolone （15 mg/kg） at 24 and 48 hours after injury. Rosiglitazone was then administered once every 12 hours for 7 consecutive days. Our results demonstrated that a combined treatment with methylprednisolone and rosiglitazone had a more pronounced effect on attenuation of inflammation and cell apoptosis, as well as increased functional recovery, compared with either single treatment alone, indicating that a combination better pro- moted recovery of neurological function after injury.

关键词： nerve regeneration spinal cord injury methylprednisotone rosiglitazone inflammation drug therapy anti-inflammatory agents functional recovery neural regeneration

EVALUATION OF DUCTILE FRACTURE CRITERIA IN A GENERAL THREE-DIMENSIONAL STRESS STATE CONSIDERING THE STRESS TRIAXIALITY AND THE LODE PARAMETER

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2013年第6期26卷 642-658页

作者： Yanshan lou Hoon Huh School of Mechanical Aerospace and Systems EngineeringKAIST335GwahangnoDaeduk Science TownDaejeon305-701South Korea

This paper is concerned with evaluation of various ductile fracture criteria in a general three-dimensional stress state of stress triaxiality, the Lode parameter and the equiva- lent plastic strain to fracture. Evaluation is carried out by comparing fracture loci constructed by fracture criteria to experimental results of A12024-T351. Comparison demonstrates that the Modified Mohr-Coulomb criterion and a newly proposed criterion provide sufficient predictabil- ity of fracture strain. Moreover, evaluation is emphasized on the predicted cut-off value for stress triaxiality. The evaluation demonstrates that the Cockcroft-Latham, Brozzo, Oh, Ko-Huh and the new criteria coupled a reasonable cut-off value for ductile materials.

关键词： fracture alloys ductile material fracture locus metal forming

Directional Solidification Assisted by Liquid Metal Cooling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2007年第3期23卷 289-300页

作者： Jian ZHANG Langhong lou Superalloys Division Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

An overview of the development and current status of the directional solidification process assisted by liquid metal cooling （LMC） has been presented in this paper. The driving force of the rapid development of the LMC process has been analyzed by considering the demands of （1） newer technologies that can provide higher thermal gradients for alleviated segregation in advanced alloy systems, and （2） better production yield of the large directionally solidified superalloy components. The brief history of the industrialization of the LMC process has been reviewed, followed by the discussion on the LMC parameters including selection of the cooling media, using of the dynamic baffle, and the influence of withdrawal rates and so on. The microstructure and mechanical properties of the traditional superalloys processed by LMC, as well as the new alloys particularly developed for LMC process were then described. Finally, future aspects concerning the LMC process have been summarized.

关键词： Directional solidification Liquid metal cooling Superalloys Microstructure Mechanical properties

Decision making for pancreatic resection in patients with intraductal papillary mucinous neoplasms

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2013年第9期19卷 1451-1457页

作者： Bin Xu Wei-Xing Ding Da-yong Jin Dan-Song Wang Wen-Hui lou Department of General Surgery Shanghai Tenth People's Hospital Tongji University School of Medicine Department of General Surgery Zhong Shan Hospital Fudan University

AIM: To identify a practical approach for preoperative decision-making in patients with intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. METHODS: Between March 1999 and November 2006, the clinical characteristics, pathological data and computed tomography/magnetic resonance imaging (CT/MRI) of 54 IPMNs cases were retrieved and analyzed. The relationships between the above data and decision-making for pancreatic resection were analyzed using SPSS 13.0 software. Univariate analysis of risk factors for malignant or invasive IPMNs was performed with regard to the following variables: carcinoembryonic antigen, carbohydrate antigen 19-9 (CA19-9) and the characteristics from CT/MRI images. Receiver operating characteristic (ROC) curve analysis for pancreatic resection was performed using significant factors from the univariate analysis. RESULTS: CT/MRI images, including main and mixed duct IPMNs, tumor size > 30 mm or a solid component appearance in the lesion, and preoperative serum CA19-9 > 37 U/mL had good predictive value for determining pancreatic resection (P < 0.05), but with limitations. Combining the above factors (CT/MRI images and CA19-9) improved the accuracy and sensitivity for determining pancreatic resection in IPMNs. Using ROC analysis, the area under the curve reached 0.893 (P<0.01, 95%CI: 0.763-1.023), with a sensitivity, specificity, positive predictive value and negative predictive value of 95.2%, 83.3%, 95.2% and 83.3%, respectively. CONCLUSION: Combining preoperative CT/MRI images and CA19-9 level may provide useful information for surgical decision-making in IPMNs.

关键词： Intraductal papillary mucinous neoplasms Surgical decision-making Carbohydrate antigen 19-9 Computed tomography/magnetic resonance imaging Predictor