检索结果-南通市图书馆

Reliability analysis of shallow tunnels using the response surface methodology

在线全文

学校读者我要写书评

暂无评论

Underground Space 2017年第4期2卷 246-258页

作者： adam Hamrouni Daniel Dias Badreddine Sbartai Grenoble Alpes Uniersity Laboratory 3SRGrenobleFrance Mohamnmed Cherif Messaadia University Laboratory InfraResSouk-AhrasAlgeria Department of Civil Engineering University Bdji Mokhtar Annaba&LMGHU LaboratoryUniversity 204out1955 SkikdaAlgeria

A probabilistic study of a circular tunnel excavated in a soil mass using the response surface methodology(RSM)is presented.A deterministic model based on two-dimensional numerical simulations in a transversal section is used,and the serviceability limit state(SLS)is considered in the *** model permits the surface settlement curve and the bending moment on the tunnel lining to be *** the soil parameters are considered as random ***ﬁrst-order reliability method(FORM)and the response surface methodology(RSM)are utilized for the assessment of the Hasofer-Lind reliability index(bHL)optimized by the use of a genetic algorithm(GA).Two assumptions(normal and non-normal distribution)were used for the random *** comparison analysis considering a correlation between the friction angle and the cohesion indicates that the results are conservative if a negative correlation among strength parameters is not taken into *** assumption of a non-normal distribution for the random variables has an important effect on the reliability index for the practical range of values of surface settlements.

关键词： Tunnel Convergence-conﬁnement method FORM Response surface reliability Limit states Approximate performance function Genetic algorithm

Safety of the long-term use of proton pump inhibitors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2010年第19期16卷 2323-2330页

作者： Alan br Thomson Michel D Sauve Narmin Kassam Holly Kamitakahara Division of General Internal Medicine Faculty of Medicine University of Alberta Edmonton AB T6G 2B7 Alberta Canada

The proton pump inhibitors (PPIs) as a class are remarkably safe and effective for persons with peptic ulcer disorders. Serious adverse events are extremely rare for PPIs, with case reports of interstitial nephritis with omeprazole, hepatitis with omeprazole and lansoprazole, and disputed visual disturbances with pantoprazole and omeprazole. PPI use is associated with the development of fundic gland polyps (FGP); stopping PPIs is associated with regression of FGP. In the absence of Helicobacter pylori infection, the long-term use of PPIs has not been convincingly proven to cause or be associated with the progression of pre-existing chronic gastritis or gastric atrophy or intestinal metaplasia. Mild/modest hypergastrinemia is a physiological response to the reduction in gastric acid secretion due to any cause. The long-term use of PPIs has not been convincingly proven to cause enterochromaff in-like cell hyperplasia or carcinoid tumors. PPIs increase the risk of community acquired pneumonia, but not of hospital acquired (nosocomial) pneumonia. There is no data to support particular care in prescribing PPI therapy due to concerns about risk of hip fracture with the long-termuse of PPIs. Long-term use of PPIs does not lead to vitamin B12 def iciencies, except possibly in the elderly, or in persons with Zollinger-Ellison Syndrome who are on high doses of PPI for prolonged periods of time. There is no convincingly proven data that PPIs increase the risk of Clostridium difficile-associated diarrhea in persons in the community. The discontinuation of PPIs may result in rebound symptoms requiring further and even continuous PPI use for suppression of symptoms. As with all medications, the key is to use PPIs only when clearly indicated, and to reassess continued use so that long-term therapy is used judiciously. Thus, in summary, the PPIs are a safe class of medications to use longterm in persons in whom there is a clear need for the maintenance of extensive acid inhibition.

关键词： Acid inhibition Drug safety Osteoporosis Pneumonia Enteric infections

FIB Secondary Etching Method for Fabrication of Fine CNT Forest Metamaterials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2017年第4期9卷 73-80页

作者： adam Pander Akimitsu Hatta Hiroshi Furuta Department of Electronic and Photonic Systems Engineering Kochi University of TechnologyTosayamadaKamiKochi 782-8502Japan Center for Nanotechnology Research InstituteKochi University of TechnologyTosayamadaKamiKochi 782-8502Japan

Anisotropic materials, like carbon nanotubes(CNTs), are the perfect substitutes to overcome the limitations of conventional metamaterials; however, the successful fabrication of CNT forest metamaterial structures is still very challenging. In this study, a new method utilizing a focused ion beam(FIB) with additional secondary etching is presented, which can obtain uniform and fine patterning of CNT forest nanostructures for metamaterials and ranging in sizes from hundreds of nanometers to several micrometers. The influence of the FIB processing parameters on the morphology of the catalyst surface and the growth of the CNT forest was investigated, including the removal of redeposited material,decreasing the average surface roughness(from 0.45 to 0.15 nm), and a decrease in the thickness of the Fe *** results showed that the combination of FIB patterning and secondary etching enabled the growth of highly aligned, highdensity CNT forest metamaterials. The improvement in the quality of single-walled CNTs(SWNTs), defined by the very high G/D peak ratio intensity of 10.47, demonstrated successful fine patterning of CNT forest for the first time. With a FIB patterning depth of 10 nm and a secondary etching of 0.5 nm, a minimum size of 150 nm of CNT forest metamaterials was achieved. The development of the FIB secondary etching method enabled for the first time, the fabrication of SWNT forest metamaterials for the optical and infrared regime, for future applications, e.g., in superlenses, antennas,or thermal metamaterials.

关键词： Carbon nanotubes Metamaterial FIB patterning Secondary etching method Chemical vapor deposition

Crystal Structure of Arabidopsis thaliana Dawdle Forkhead-Associated Domain Reveals a Conserved Phospho-Threonine Recognition Cleft for Dicer-Like 1 Binding

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2013年第4期6卷 1290-1300页

作者： Satoru Machida Y.adam Yuan Department of Biological Sciences and Centre for Bioimaging Sciences National University of Singapore 14 Science Drive 4 Singapore 117543 Singapore Temasek Lifesciences Laboratory National University of Singapore 1 Research Link Singapore 117604 Singapore Mechanobiology Institute National University of Singapore T-lab Building 5A Engineering Drive 1 Singapore 117411 Singapore

Dawdle （DDL） is a microRNA processing protein essential for the development of Arabidopsis. DDL contains a putative nuclear localization signal at its amino-terminus and forkhead-associated （FHA） domain at the carboxyl-termi- nus. Here, we report the crystal structure of the FHA domain of Arabidopsis Dawdle, determined by multiple-wavelength anomalous dispersion method at 1.7-A resolution. DDL FHA structure displays a seven-stranded 13-sandwich architec- ture that contains a unique structural motif comprising two long anti-parallel strands. Strikingly, crystal packing of the DDL FHA domain reveals that a glutamate residue from the symmetry-related DDL FHA domain, a structural mimic of the phospho-threonine, is specifically recognized by the structurally conserved phospho-threonine binding cleft. Consistently with the structural observations, co-immuno-precipitation experiments performed in Nicotiana benthami- ana show that the DDL FHA domain co-immuno-precipitates with DCL1 fragments containing the predicted pThr＋3（lle/ Val/Leu/Asp） motif. Taken together, we count the recognition of the target residue by the canonical binding cleft of the DDL FHA domain as the key molecular event to instate FHA domain-mediated protein-protein interaction in plant miRNA processing.

关键词： Arabidopsis DCL1 Arabidopsis DDL forkhead-associated domain phospho-threonine microRNA processing.

Apoptosis and DNA damage in human spermatozoa

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2011年第1期13卷 36-42页

作者： R John Aitken adam J Koppers ARC Centre of Excellence in Biotechnology and Development Priority Research Centre in Reproductive Science Discipline of Biological Sciences School of Environmental and Life Sciences University of Newcastle Callaghan NSW 2308 Australia Department of Anatomy and Developmental Biology School of Biomedical Sciences Monash University Clayton VIC 3800 Australia

DNA damage is frequently encountered in spermatozoa of subfertile males and is correlated with a range of adverse clinical outcomes including impaired fertilization, disrupted preimplantation embryonic development, increased rates of miscarriage and an enhanced risk of disease in the progeny. The etiology of DNA fragmentation in human spermatozoa is closely correlated with the appearance of oxidative base adducts and evidence of impaired spermiogenesis. We hypothesize that oxidative stress impedes spermiogenesis, resulting in the generation of spermatozoa with poorly remodelled chromatin. These defective cells have a tendency to default to an apeptotic pathway associated with motility loss, caspase activation, phosphatidylserine exteriorization and the activation of free radical generation by the mitochondria. The latter induces lipid peroxidation and oxidative DNA damage, which then leads to DNA fragmentation and cell death. The physical architecture of spermatozoa prevents any nucleases activated as a result of this apoptotic process from gaining access to the nuclear DNA and inducing its fragmentation. It is for this reason that a majority of the DNA damage encountered in human spermatozoa seems to be oxidative. Given the important role that oxidative stress seems to have in the etiology of DNA damage, there should be an important role for antioxidants in the treatment of this condition. If oxidative DNA damage in spermatozoa is providing a sensitive readout of systemic oxidative stress, the implications of these findings could stretch beyond our immediate goal of trying to minimize DNA damage in spermatozoa as a prelude to assisted conception therapy.

关键词： apoptosis DNA damage oxidative stress spermatozoa

Recent advances in small bowel diseases:Part Ⅰ

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2012年第26期18卷 3336-3352页

作者： Alan br Thomson Angeli Chopra Michael Tom Clandinin Hugh Freeman Department of Medicine University of Western OntarioLondonON N6A 5A5Canada Division of General Internal Medicine University of AlbertaEdmontonAB T6G 2X8Canada Department of Agricultural Foodand Nutritional ScienceUniversity of AlbertaEdmontonAB T6G 2R1Canada Division of Gastroenterology University of British ColumbiaVancouverBC V6T 2B5Canada

As is the case in all parts of gastroenterology and hepatology,there have been many advances in our knowledge and understanding of small intestinal *** 1000 publications were reviewed for 2008 and 2009,and the important advances in basic science as well as clinical applications were *** Part Ⅰ of this Editorial Review,seven topics are considered:intestinal development;proliferation and repair;intestinal permeability;microbiotica,infectious diarrhea and probiotics;diarrhea;salt and water absorption;necrotizing enterocolitis;and immunology/*** topics were chosen because of their importance to the practicing physician.

关键词： Diarrhea Infectious diarrhea Intestinal development Intestinal proliferation and repair Intestinalpermeability Microbiotica Necrotizing enterocolitis Probiotics

Multi-regional observations and validation of the M_(3)ocean tide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2023年第10期66卷 2265-2277页

作者： adam Thomas DEVLIN Jiayi PAN Déborah IDIER School of Geography and Environment Jiangxi Normal UniversityNanchang330022China Cooperative Institute for Marine and Atmospheric Research School of Ocean and Earth Science and TechnologyUniversity of Hawai’i at MānoaHonoluluHI96822USA Department of Oceanography University of Hawai’i at MānoaHonoluluHI96822USA The Chinese University of Hong Kong Hong Kong999077China Key Laboratory of Poyang Lake Wetland and Watershed Research of Ministry of Education Nanchang330022China brGM Orléans45060France

Improved determinations of the oft-ignored third-degree ocean tides can yield better accuracy for tidal predictions,numerical model solutions,and *** only a small part of tidal range,these components can be larger at certain coastal locations due to shelf resonances and other ***,we discuss observations of the M3lunar terdiurnal tide using 9-year windowed tidal harmonic analyses at 157 tide gauges compares to a global assimilation model(TPXO9v5a),with a focus on the Western Pacific and the European ***9v5a does well in estimating the observed M_(3)amplitudes and phase lags in most regions,though determinations in coastal zones and in morphologically complex areas are coarse and often *** also employ a shallow-water model(MARS)on the European Shelf,which can yield localized improvement over *** five subregions of the European Shelf,regional root-mean-squared-errors(RMSEs)are lower(and thus a better fit)at three locations for TPXO for amplitudes,and three for phase lags,with MARS simulations being a better fit in the other *** also show that some locations have experienced significant long-term increases and/or decreases in the M_(3)amplitude over time,likely related to resonance changes under sea level rise(SLR)which can modulate the oceanic response to astronomical *** hypothesis is explored for Europe using the MARS model by applying various sea level rise scenarios,showing that the directionality(positive or negative)of the long-term changes in M_(3)amplitudes over time match the model results for more than half of our validation stations.

关键词： Third-degree tides M_(3)tide Altimetry Numerical simulation Sea level rise

Shape-changing particles for locally resolved particle geometry in DEM simulations

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第6期89卷 185-190页

作者： Enric Illana Klidi Qyteti Maik Scharnowski Maximilian brömmer Siegmar Wirtz Viktor Scherer Institute of Energy Plant Technology Ruhr-University BochumBochumGermany

Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.

关键词： Polyhedron Size change Shape change Locally resolved DEM

Determination of the Influence of c-BN+h-BN Coating Structure on brittleness

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 888-893页

作者： Maciej Kupczyk adam Lejwoda Przemyslaw Cieszkowski Przemyslaw Libuda Poznan University of Technology Institute of Mechanical Engineering Poznan PolandPoznan University of Technology Institute of Mechanical Engineering Poznan PolandPoznan University of Technology Institute of Mechanical Engineering Poznan PolandPoznan University of Technology Institute of Mechanical Engineering Poznan Poland

In the article is presented the brittleness study of boron nitride coatings deposited on cutting edges made of cemented carbides by the pulse-plasma method (PPD). Influences of the structure (density, pores, microcracks) of coating material on the brittleness and on selected technological parameters of boron nitride formation by PPD method particularly taking into account discharge voltage on brittleness are shown. Differences between values of both ai(300) and "1(5oo) coefficients characterized susceptibility to coatings cracking of investigated coating manufactured using different values of discharge voltage were defined. Results of an investigations have been confirmed usefulness of Palmqvist’s method for measurement of coating susceptibility to brittle cracking.

关键词：耐磨覆层 PVD 脆性氮化硼涂层