检索结果-南通市图书馆

influence of temperature cycling and pore fluid on tensile strength of chalk

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 2019年第2期11卷 277-288页

作者： T.Voake A.Nermoen C.Ravn?s R.i.Korsnes i.l.Fabricius University of Stavanger The National iOR Center of Norway University of Stavanger NORCE Norwegian Research Centre AS Technical University of Denmark

Calcite has a highly anisotropic thermal expansion coefficient, and repeated heating and cooling cycles can potentially destabilize chalks by breaking cement bonds between neighboring particles. Based on tensile strength measurements, we investigated how temperature cycles induce weakening of *** strength tests were performed on chalk specimens sampled from Kansas(USA) and Mons(Belgium), each with differing amounts of contact cement. Samples of the two chalk types were tested in dry and water-saturated states, and then exposed to 0, 15, and 30 temperature cycles in order to find out under what circumstances thermally induced tensile strength reduction occurs. The testing results show that the dry samples were not influenced by temperature cycling in either of the chalk types. However, in the water-saturated state, tensile strength is increasingly reduced with progressive numbers of temperature cycles for both chalk samples, especially for the more cemented Kansas chalk. The Kansas chalk demonstrated higher initial tensile strength compared to the less cemented Mons chalk, but the strength of both chalks was reduced by the same relative proportion when undergoing thermal cycles in the water-saturated state.

关键词： Tensile strength Weakening by heating and cooling cycles Anisotropic thermal expansion

Determination of the Radial Distribution of Attenuation in Single-Mode Optical Fibers

在线全文

学校读者我要写书评

暂无评论

光学学报 2003年第S1期23卷 51-52页

作者： S. Girard i.Trenteseaux Y. Ouerdane j-P Meunier A. Boukenter j-l. Derep l.Thonnérieux University jean Monnet Laboratoire TSI UMR CNRS 551623 rue du Dr Paul Michelon 42023 Saint-Etienne France SAGEM S.A. 72 - 74 rue de la Tour Billy 95101 Argenteuil France Centre Technique d'Arcueil (DGA/DCE/CTA) 16 bis avenue du Prieur de la C6te d'Or 94114 Arcueil France

A new method to determine the radial distribution of attenuation in single-mode optical fibers is proposed. As an example, radiation-induced losses in gamma-irradiated germanosilicate fibers are characterized at 633 nm.

关键词： optical fibers new method

Decorating crystalline YFe_(2-x)Al_(x) on the Mg_(60)la_(10)Ni_(20)Cu_(10) amorphous alloy as “hydrogen pump” to realize fast de/hydrogenation

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2024年第6期173卷 72-79页

作者： l.j.Huang H.Wang l.Z.Ouyang M.Zhu H.j.lin School of Materials Science and Engineering Key Laboratory of Advanced Energy Storage Materials of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510641China institute of Advanced Wear&Corrosion Resistance and Functional Materials Jinan UniversityGuangzhou 510632China

Mg-based amorphous alloys are one of the potential hydrogen storage materials but suffer from sluggish dehydrogenation/hydrogenation(de/hydrogenation)*** this work,as a new strategy,a hydrogen pump is built on the surface of amorphous alloys to solve this *** milling crystalline YFe_(2-x)Al_(x) hydrogen storage alloy with Mg_(60)la_(10)Ni_(20)Cu_(10) amorphous alloy,fine crystalline particles were seeded on amorphous alloy powder to form a“strawberry”*** to the TEM observation,a metallurgical bonding boundary formed between the Mg-based amorphous matrix and the Y-Fe-Al crystalline *** microstructure and de/hydrogenation kinetics investigation,the“hydrogen pump”effect of the seeded crystalline alloy was confirmed,which makes it much easier for the hydrogen to dissociate on and diffuse through the surface of the Mg-based amorphous *** such effect,the H absorption rate of Mg_(60)la_(10)Ni_(20)Cu_(10) amorphous alloy became almost eight times faster and it absorbs ~2.8 wt.% in 1 h at 130℃ under 4.5 MPa-H_(2).Further,fast hydrogenation can even achieve at 70℃ and the low-temperature dehydrogenation kinetics of the amorphous hydride can be also greatly *** present work proves that surface modification is of great importance for obtaining Mg-based amorphous alloy with ideal hydrogen storage performance.

关键词： Hydrogen storage Mg-based amorphous alloy Hydrogen pump Composite structure

Relationship between the exocrine and endocrine pancreas after acute pancreatitis

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 2014年第45期20卷 17196-17205页

作者： Stephanie l M Das james i C Kennedy Rinki Murphy Anthony R j Phillips john A Windsor Maxim S Petrov Department of Surgery University of Auckland Department of Medicine University of Auckland

AiM: To determine the prevalence and time course of pancreatic exocrine insufficiency in individuals with newly diagnosed prediabetes or diabetes mellitus after acute pancreatitis.

关键词： Pancreatogenic diabetes Pancreatic exocrine insufficiency Acute pancreatitis Endocrine insufficiency

Extragalactic dispersion measures of fast radio bursts

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2015年第10期15卷 1629-1638页

作者： jun Xu j.l.Han National Astronomical Observatories Chinese Academy of Sciences

Fast radio bursts show large dispersion measures, much larger than the Galactic dispersion measure foreground. Therefore, they evidently have an extragalac- tic origin. We investigate possible contributions to the dispersion measure from host galaxies. We simulate the spatial distribution of fast radio bursts and calculate the dis- persion measures along the sightlines from fast radio bursts to the edge of host galaxies by using the scaled NE2001 model for thermal electron density distributions. We find that contributions to the dispersion measure of fast radio bursts from the host galaxy follow a skew Gaussian distribution. The peak and the width at half maximum of the dispersion measure distribution increase with the inclination angle of a spiral galaxy, to large values when the inclination angle is over 70~. The largest dispersion measure produced by an edge-on spiral galaxy can reach a few thousand pc cm-3, while the dispersion measures from dwarf galaxies and elliptical galaxies have a maximum of only a few tens of pc cm-3. Notice, however, that additional dispersion measures of tens to hundreds of pc cm-3 can be produced by high density clumps in host galaxies. Simulations that include dispersion measure contributions from the large Magellanic Cloud and the Andromeda Galaxy are shown as examples to demonstrate how to ex- tract the dispersion measure from the intergalactic medium.

关键词： galaxies: iSM -- radio continuum: iSM -- iSM: general

Altered expression of m^(1)A regulatory genes is associated with oncogenic pathways,overall survival,and infiltration of immune cells in diverse human cancers

在线全文

学校读者我要写书评

暂无评论

Genes & Diseases 2023年第3期10卷 739-742页

作者： Renhua Song justin j-l Wong Epigenetics and RNA Biology Program Centenary institute The University of SydneyCamperdown 2050Australia Faculty of Medicine and Health The University of SydneyCamperdown 2050Australia

Of over 170 types of RNA modifications discovered,N^(6)-methyladenosine(m^(6)A)is the most actively studied.m6A confers oncogenic potential,maintains cancer stem cells,and is associated with cancer-related outcomes.^(... 详细信息

关键词： cancer maintain immune

OSCillATiON AND VARiATiON OF THE lAGUERRE HEAT AND POiSSON SEMiGROUPS AND RiESZ TRANSFORMS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2012年第3期32卷 907-928页

作者： j.j.Betancor R.Crescimbeni j.l.Torrea Departamento de An'aisis Matema'ico Universidad de La Laguna38271-La LagunaTenerifeIslas CanariasSpain Departamento de Matema'ica Universidad Nacional del ComahueBuenos Aires 14008300 Neuqu'enArgentina Departamento de Matem'aticas Facultad de CienciasUniversidad Auto'noma de Madrid28049 MadridSpain

in this article, we study lP-boundedness properties of the oscillation and vari- ation operators for the heat and Poissson semigroup and Riesz transforms in the laguerre settings. Also, we characterize Hardy spaces as... 详细信息

关键词： Oscillation variation heat laguerre semigroup Riesz transforms

Analysis of inhibition of concrete steel-rebar corrosion by Na_2Cr_2O_7 concentrations:implications for conflicting reports on inhibitor effectiveness

在线全文

学校读者我要写书评

暂无评论

journal of Central South University 2013年第12期20卷 3697-3714页

作者： j.O.Okeniyi i.O.Oladele i.j.Ambrose S.O.Okpala O.M.Omoniyi C.A.loto A.P.i.Popoola Mechanical Engineering Department Covenant University Chemical Metallurgical and Materials Engineering Department Tshwane University of Technology

Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.

关键词： corrosion inhibitor effectiveness saline/marine and industrial/microbial environments concrete steel-rebar normal andGumbel probability distribution functions Kolmogorov-Smirnov statistics tests of significance

One-step multi-compositional oxidation of YSi alloy:Experiments and ab initio computation

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2023年第27期158卷 253-262页

作者： W.j.Wang j.C.luo l.Chen G.j.Yang State Key laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an jiaotong University Suzhou institute Suzhou 215123China

YSi alloy is a promising candidate as oxidation resistant coatings for both the bond coat of environmental barrier coatings(EBCs)and anti-ablation coatings at a high temperature of∼1300℃.in this study,a one-step multi-compositional oxidation by rapid heating oxidation mode is proposed to reduce the oxidation rate by 3.6 times compared to conventional slow heating oxidation *** show that preferentially formed Y_(2)O_(3) oxide initiates a multi-step oxidation,produces a cracking and porous oxides,and thereby resulting in a fast oxidation with *** one-step multi-compositional oxidation with a compact and dense Y_(2)Si_(2)O_(7)scale contributes to the much better oxidation resistance for rapid heating oxidation mode of YSi *** stable formation of Y_(2)Si_(2)O_(7)scale is comprehensively understood by the energy barrier,charge density and electronic level based on density functional *** study demonstrates a promising application of YSi alloy by rapid heating oxidation mode.

关键词： YSi alloy One-step oxidation Multi-compositional scale Y_(2)Si_(2)O_(7) Energy barrier