检索结果-南通市图书馆

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 1967-1976页

作者： Meng Meng luke P.Frash J.william Carey Mohamed Mehana Wenfeng Li Bailian Chen Earth and Environmental Sciences Los Alamos National LaboratoryLos AlamosNMUSA

Debonding at the cement-casing interface is recognized as a principal failure mechanism leading to CO_(2) leakage in *** detachment gives rise to a microannulus,which notably possesses greater permeability than undamaged cement,undermining its sealing ***,the permeability of the microannulus is regarded as a uniform value throughout the ***,fundamentally,a microannulus is one type of fracture,and its gap or aperture size is affected by the effective *** this work,we developed a unique experimental *** equipment facilitates the curing of cement inside a steel casing,the formation of a microannulus between the casing and the cement,and the investigation of the fluid flow dynamics along the microannulus under laboratory-replicated in situ *** microannulus was formed by injecting fluid from one end of the setup,and receiving similar amount of fluid on the other end signified the development of the leakage ***,strain gauges affixed to the casing’s external surface yielded key information on the microannulus’s opening and *** observed a noticeable decline in microannulus hydraulic aperture(or permeability)in relation to effective stress and an exponential equation fits their *** findings also indicate a distinct behavior when comparing liquid CO_(2) with ***,it is easier for liquid CO_(2) to create the ***,the hydraulic aperture range for this microannulus(0.7-6 mm)is considerably smaller than that created by water flow(2-17 mm).Finally,we integrated the stressdependent microannulus aperture size into the combined analysis of well mechanical integrity and well *** outcomes consistently demonstrated that when factoring in the stress-dependent aperture sizes,the leakage rates are 3e5 times compared to a fixed aperture *** traditional assumption of a constant aperture significantly underestimates fluid leakage risks.

关键词： Microannulus Leakage assessment Aperture size Triaxial experiment Carbon sequestration

Hydromechanical characterization of gas transport amidst uncertainty for underground nuclear explosion detection

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

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2019-2032页

作者： Wenfeng Li Chelsea W.Neil J william Carey Meng Meng luke P.Frash Philip H.Stauffer Earth and Environmental Sciences Los Alamos National LaboratoryLos AlamosNM87544USA Department of Mineral Engineering New Mexico TechSocorroNM87801USA

Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the *** this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing *** testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty *** porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress *** Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity<1%,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous *** experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be

关键词： Underground nuclear explosion uncertainty quantification Radionuclide transport Biot effective stress coefficient Fracture permeability Matrix permeability

Structure-function Relationships in Human Hypoxanthine-guanine Phosphoribosyltransferase(HGPRT) by Random Mutagenesis

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

Chemical Research in Chinese Universities 2006年第2期22卷 251-252页

作者： luke guddat Anthony Farlow John de Jersey Department of Biochemistry and Molecular Biology University of Queensland St Lucia Queensland 4072 Australia

Hypoxanthine-guanine phosphoribosyltransferase （ HGPRT, EC 2.***.2.8） is a key enzyme of the purine salvage pathway, which allows recycling of purine bases into DNA and RNA. It is widely distributed in nature and has been studied both in prokaryotes and eukaryotes. In humans, a complete lack of HGPRT activity causes the Lesch-Nyhan syndrome, which is characterized by hyperuricaemia and neural disorders,

关键词： Hypoxanthine-guanine phosphoribosyltransferase Random mutagenesis Structure-function relationship

Mammalian-like Purple Acid Phosphatases in Plants

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2006年第2期22卷 263-264页

作者： John de Jersey FAN Hong-kuan Gary Schenk luke guddat Susan Hamilton Department of Biochemistry and Molecular Biology University of Queensland St Lucia Queensland 4072 Australia

Introduction Purple acid phosphatases （PAPs） comprise of a family of binuclear metal-containing hydrolases, some members of which have been isolated and characterized from animal, plant and fungal sources . PAPs not only catalyze the hydrolyses of a wide range of phosphate esters and anhydrides under acidic reaction conditions, but also catalyze the generation of hydroxyl radicals in a Fenton-like reaction, by virtue of the presence of a redox-active binuclear metal center. Inmammals,

关键词： Purple acid phosphatase Mammalian-like GST-fusion protein

HERBICIDES THAT INHIBIT ACETOLACTATE SYNTHASE

在线全文

学校读者我要写书评

暂无评论

Frontiers of Agricultural Science and Engineering 2022年第1期9卷 155-160页

作者： Thierry LONHIENNE Mario Daniel GARCIA Yu Shang LOW luke W.guddat School of Chemistry and Molecular Bioscience The University of QueenslandQueensland 4072Australia

1 INTRODUCTION Herbicides are an essential pillar in modern agricultural *** are used to selectively reduce the growth of weeds in crops and natural *** weed mitigating chemicals date back to Roman times and include substances as simple as table salt,sulfuric acid and carbon ***,these were non-selective,required high application rates and could be toxic not only to the target weeds but to other plants and to *** first major advance in the development of tailored herbicides began in the mid 1940s with the development of the first organic growth regulators such as 2,4 dichlorophenoxyacetic acid(2,4-D)[1].The next major advance came in the 1970s with the discovery of glyphosate[2],marketed as Roundup,a herbicide that is routinely used to eradicate broad leaf weeds and grasses.

关键词： crops weed routine

Discovery of the first macrolide antibiotic binding protein in Mycobacterium tuberculosis： a new antibiotic resistance drug target

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2018年第11期9卷 971-975页

作者： Qingqing Zhang Huijuan Liu Xiang Liu Dunquan Jiang Bingjie Zhang Hongliang Tian Cheng Yang luke W. guddat Haitao Yang Kaixia Mi Zihe Rao College of Life Sciences Nankai University Tianjin 300071 China College of Pharmacy Nankai University Tianjin 300071 China CAS Key Laboratory of Pathogenic Microbiology and Immunology Institute of Microbiology Chinese Academy of Sciences Beijing100101 China School of Life Sciences Tianjin University Tianjin 300072 China School of Chemistry and Molecular Biosciences The University ofQueensland Brisbane QLD 4072 Australia Laboratory of Structural Biology School of Medicine TsinghuaUniversity Beijing 100084 China Tianjin International Joint Academy of Biotechnology & Medicine Tianjin 300457 China

Dear Editor The prevalence of multidrug-resistant Mycobacterium tuberculosis （M. tuberculosis） is an increasing problem worldwide （Zumla et al., 2013; Dong et al., 2015）. According to a 2014 World Health Organization （WHO） report, 480,000 individuals world-wide .developed multidrug-resistant tuber- culosis （MDR-TB） and more than 100 countries have cases of extensively drug-resistant tuberculosis （XDR-TB）. Com- pared with drug-susceptible TB, MDR-TB and XDR-TB require prolonged therapeutic treatment with a combination of a number of second-line drugs （Chen et al., 2013）. For patients where TB remains persistent despite prolonged therapy with second-line TB drugs, the add-on agents including bedaquiline and delamanid are recommended for salvage therapy （GUnther, 2014; WHO, 2014; Shim and Jo, 2013）.

关键词： MOLECULAR-MECHANISMS ABC

Broad spectrum antibiotic-degrading metallo-β-lactamases are phylogenetically diverse

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2020年第8期11卷 613-617页

作者： Marcelo Monteiro Pedroso David W.Waite Okke Melse Liam Wilson Natasa Mitic Ross P.McGeary Iris Antes luke W.guddat Philip Hugenholtz Gerhard Schenk School of Chemistry and Molecular Biosciences The University of QueenslandSt.LuciaQLDBrisbane 4072Australia Australian Centre for Ecogenomics The University of QueenslandSt.LuciaQLDBrisbane 4072Australia Center for Integrated Protein Science Munich at the TUM School of Life Sciences Technische Universit(a)t München85354 FreisingGermany Department of Chemistry Maynooth UniversityMaynoothCo.KildareIreland

Dear Editor, Antibiotic resistance has emerged as a major threat to global health;multi-drug resistant bacteria already kill more patients in the United States each year than HIV/AIDS, Parkinson's disease, emphysema and homicide combined (Laxminarayan et al., 2013).Among the most effective bacterial resistance mechanisms are β-lactamases, a family of enzymes that are divided into four distinct *** A, C and D (serine-β-lactamases, SBLs) use a catalytic site serine residue to initiate inactivation of the antibiotic, while Class B (metallo-β-lactamases, MBLs) relies on a Zn2+-activated hydroxide (Walsh et al., 2005;Bush and Jacoby,2010;Mitic et al., 2014;Lisa et al., 2017).Clinically relevant inhibitors of Class C and D SBLs are available and in use (e.g., clavulanic acid (CA), Drawz et al., 2010), but for MBLs the search for such inhibitors has remained challenging (McGeary et al., 2017).

关键词： hydroxide metallo spectrum

Cryo-EM structures of a prokaryotic heme transporter CydDC

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

Protein & Cell 2023年第12期14卷 919-923页

作者： Chen Zhu Yanfeng Shi Jing Yu Wenhao Zhao Lingqiao Li Jingxi Liang Xiaolin Yang Bing Zhang Yao Zhao Yan Gao Xiaobo Chen Xiuna Yang Lu Zhang luke W.guddat Lei Liu Haitao Yang Zihe Rao Jun Li Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology ShanghaiTech UniversityShanghai 201210China National Clinical Research Center for Infectious Disease Shenzhen Third People's HospitalShenzhen 518112China Laboratory of Structural Biology Tsinghua UniversityBeijing 100084China State Key Laboratory of Medicinal Chemical Biology Nankai UniversityTianjin 300353China Innovative Centerfor Pathogen Research Guangzhou LaboratoryGuangzhou 510005China School of Chemistry and Molecular Biosciences The University of QueenslandBrisbaneQLD 4072Australia

DearEditor,Heme is an essential cofactor required across all kingdoms of life utilized in numerous biological processes,including cellular *** is a prokaryotic ATP-binding cassette(ABC)transporter required for heme assembling in respiratory cytochrome bd oxidase(Georgiou et al.,1987;Poole et al.,1989),a promising target for drug discovery(Borisov et al.,2011).CydDC is thought to play a role in maintaining an optimum periplasmic redox poise that is required for the incorporation of heme cofactors(Yamashita et al.,2014).It also suggested that CydDC is involved in heme processing by mediating glutathione/cysteine translocation(Cook and Poole,2000;Cook et al.,2002),although a role in heme translocation seems unlikely(Yamashita et al.,2014).To date,CydDC has been shown to be important for disulfide bond formation,motility,respiration,and tolerance to nitric oxide and antibiotics(Poole et al.,2019).

关键词： utilized disulfide Poole

Structural insights into substrate recognition by the type Ⅶ secretion system

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2020年第2期11卷 124-137页

作者： Shuhui Wang Kaixuan Zhou Xiaolin Yang Bing Zhang Yao Zhao Yu Xiao Xiuna Yang Haitao Yang luke Wguddat Jun Li Zihe Rao Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology ShanghaiTech UniversityShanghai 201210China CAS Center for Excellence in Molecular Cell Science Shanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesShanghai 200031China State Key Laboratory of Medicinal Chemical Biology College of Life Sciences and College of PharmacyNankai UniversityTianjin 300353China Laboratory of Structural Biology Tsinghua UniversityBeijing 100084China National Laboratory of Biomacromolecules CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China School of Chemistry and Molecular Biosciences The University of QueenslandBrisbaneQLD 4072Australia University of Chinese Academy of Sciences Beijing 100101China

Type VII secretion systems(T7SSs)are found in many disease related bacteria including Mycobacterium tuberculosis(Mtb).ESX-1[early secreted antigen 6 kilodaltons(ESAT-6)system 1]is one of the five subtypes(ESX-1?5)of T7SSs in Mfb,where it delivers virulence factors into host macrophages during ***,little is known about the molecular details as to how this ***,we provide high-resolution crystal structures of the C-terminal ATPase3 domains of EccC subunits from four different Mtb T7SS *** structures adopt a classic RecA-like a/p fold with a conserved Mg-ATP binding *** structure of EccCbl in complex with the C-terminal peptide of EsxB identifies the location of substrate recognition site and shows how the specific signaling module XxxxMxF"for Mtb ESX-1 binds to this site resulting in a translation of the bulge loop.A comparison of all the ATPase3 structures shows there are significant differences in the shape and composition of the signal recognition pockets across the family,suggesting that distinct signaling sequences of substrates are required to be specifically recognized by different T7SSs.A hexameric model of the EccC-ATPase3 is proposed and shows the recognition pocket is located near the central substrate translocation *** diameter of the channel is?25-A,with a size that would allow helix-bundle shaped substrate proteins to bind and pass ***,our work provides new molecular insights into substrate recognition for Mtb T7SS subtypes and also a possible transportation mechanism for substrate and/or virulence factor secretion.

关键词： type VII secretion system Mycobacterium tuberculosis ATPase virulence factor substrate recognition