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On the experim.ntal characterization of the fluid volum. influence on the friction between rough surfaces

Friction 2023年第7期11卷 1334-1348页

作者： Lukas STAHL m.chael m.LLER Georg-peter OSTERm.YER Institute of Dynam.cs and Vibrations Technische Universität BraunschweigBraunschweig 37106Germany

The load-bearing behaviour of lubricated contacts depends prim.rily on the norm.l force,the relative velocity,and the ***,with the aid of the Stribeck curve,it is usually well possible to characterize whether hydrodynam.cs,m.xed friction,or boundary friction is m.re likely to be *** fact that the load regim. can also depend on the fluid quantity is obvious,but has hardly been system.tically investigated so *** for contacts with m.croscopic roughness,the defined application of a very sm.ll am.unt of fluid is a very challenging *** this paper,a very fundam.ntal study shows how a pin-on-disc tribom.ter can be used to achieve the transition from.dry friction via m.xed friction to predom.nant hydrodynam.cs by the am.unt of supplied *** experim.nts are carried out on sam.les filed with different *** addition,the sim.ltaneous influence of partial filling and norm.l force as well as relative velocity is also *** good reproducibility has been practically reached over the entire range of the *** the quantities for the coefficient of friction(COF),it was concluded that close to full filling,a reduction of the fluid quantity has a sim.lar effect on the COF as the reduction of the *** property goes along with the com.on theory of starved lubricated *** behaviour was not observed to the sam. extent for the norm.l *** the vicinity of sm.ller fluid quantities,the COF increases very rapidly with further reduction in fluid quantity,far m.re disproportionately than that with reduction in *** a deeper understanding of this problem.various practical issues such as idling or the run-up process in bearings can also be studied in a m.re focused m.nner.

关键词： starved lubrication Stribeck curve pin-on-disc tribom.ter fluid supply experim.ntal studies

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Efficient Silencing of Endogenous m.croRNAs Using Artificial m.croRNAs in Arabidopsis thaliana

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m.lecular Plant 2011年第1期4卷 157-170页

作者： Andrew L. Eam.ns Claire Agius Nell A. Sm.th peter m. Waterhouse m.ng-Bo Wang CSIRO Plant Industry GPO Box 1600 Canberra ACT 2601 Australia School of m.lecular Bioscience University of Sydney Sydney NSW 2006 Australia

We report here that the expression of endogenous m.croRNAs （m.RNAs） can be efficiently silenced in Arabi- dopsis thaliana （Arabidopsis） using artificial m.RNA （am.RNA） technology. We dem.nstrate that an am.RNA designed to target a m.ture m.RNA directs silencing against all m.RNA fam.ly m.m.ers, whereas an am.RNA designed to target the stem.loop region of a m.RNA precursor transcript directs silencing against only the individual fam.ly m.m.er targeted. Furtherm.re, our results indicate that am.RNAs targeting both the m.ture m.RNA and stem.loop sequence direct RNA silencing through cleavage of the m.RNA precursor transcript, which presum.bly occurs in the nucleus of a plant cell during the initial stages of m.RNA biogenesis. This suggests that sm.ll RNA （sRNA）-guided RNA cleavage in plants occurs not only in the cytoplasm. but also in the nucleus. m.ny plant m.RNA gene fam.lies have been identified via sequencing and bio- inform.tic analysis, but, to date, only a sm.ll tranche of these have been functionally characterized due to a lack of ef- fective forward or reverse genetic tools. Our findings therefore provide a new and powerful reverse-genetic tool for the analysis of m.RNA function in plants.

关键词： m.croRNA artificial m.croRNA RNA silencing.

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A test of genetic association am.ng m.le nuptial coloration, fem.le m.ting preference, and m.le aggression bias within a polym.rphic population of cichlid fish

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Current Zoology 2013年第2期59卷 221-229页

作者： Inke van der SLUIJS peter D. DIJKSTRA Charlotte m. LINDEYER BertanneVISSER Alan m. Sm.TH Ton G. G. GROOTHUIS Jacques J. m. van ALPHEN Ole SEEHAUSEN Departm.nt of Anim.l Ecology Institute of Biology Leiden University PO Box 9516 2300 RA Leiden The Netherlands The University of Texas at Austin Section of Integrative Biology 1 University Station-C0930 Austin TX 78712 United States Departm.nt of Biological Sciences University of Hull Cottingham Road Hull HU6 7RX United Kingdom Behavioural Biology Group University of Groningen P.O. Box 14 9750 AA Haren The Netherlands Institute of Zoology University of Bern Baltzerstrasse CH-3012 Bern Switzerland Eawag Swiss Federal Institute for Aquatic Science and Technology Centre of Ecology Evolution & Biogeochemistry Depart- ment ofFish Ecology & Evolution Seestrasse 97 6047 Kastanienbaum Switzerland

Both inter- and intrasexual selection have been im.licated in the origin and m.intenance of species-rich taxa with di- verse sexual traits. Sim.ltaneous disruptive selection by fem.le m.te choice and m.le-m.le com.etition can, in theory, lead to ~,;peciation without geographical isolation if both act on the sam. m.le trait. Fem.le m.te choice can generate discontinuities in gene flow, while m.le-m.le com.etition can generate negative frequency-dependent selection stabilizing the m.le trait polym.r- phism. Speciation m.y be facilitated when m.ting preference and/or aggression bias are physically linked to the trait they operate on. We tested for genetic associations am.ng fem.le m.ting preference, m.le aggression bias and m.le coloration in the Lake Victoria cichlid Pundam.lia. We crossed fem.les from.a phenotypically variable population with m.les from.both extrem. ends of the phenotype distribution in the sam. population （blue or red）. m.le offspring of a red sire were significantly redder than m.les of a blue sire, indicating that intra-population variation in m.le coloration is heritable. We tested m.ting preferences of fem.le offspring and aggression biases of m.le offspring using binary choice tests. There was no evidence for associations at the fam.ly level between fem.le m.ting preferences and coloration of sires, but dam.identity had a significant effect on fem.le m.te prefe- rence. Sons of the red sire directed significantly m.re aggression to red than blue m.les, whereas sons of the blue sire did not show any bias. There was a positive correlation am.ng individuals between m.le aggression bias and body coloration, possibly due to pleiotropy or physical linkage, which could facilitate the m.intenance of color polym.rphism.[Current Zoology 59 （2）： 221-229, 2013].

关键词： Disruptive selection Sexual selection Speciation Pundam.lia Linkage disequilibrium

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Drug treatm.nt of functional dyspepsia

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World Journal of Gastroenterology 2006年第17期12卷 2694-2700页

作者： Klaus m.nkem.ller peter m.lfertheiner Division of Gastroenterology Hepatology and Infectious Diseases Otto-von-Guericke Medical SchoolUniversity of MagdeburgMagdeburgGermany

Sym.tom.tic im.rovem.nt of patients with functional dyspepsia after drug therapy is often incom.lete and obtained in not m.re than 60% of patients. This is likely because functional dyspepsia is a heterogeneous disease. Although great advance has been achieved with the consensus definitions of the Rom. I and II criteria, there are still som. aspects about the definition of functional dyspepsia that require clarification. The Rom. criteria explicitly recognise that epigastric pain or discom.ort m.st be the predom.nant com.laint in patients labelled as suffering from.functional dyspepsia. However, this strict definition can create problem. in the daily prim.ry care clinical practice, where the patient with functional dyspepsia presents with m.ltiple sym.tom.. Before starting drug therapy it is recom.ended to provide the patient with an explanation of the disease process and reassurance. A thorough physical exam.nation and judicious use of laboratory data and endoscopy are also indicated. In general, the approach to treat patients with functional dyspepsia based on their m.in sym.tom.is practical and effective. Generally, patients should be treated with acid suppressive therapy using proton-pum. inhibitors if the predom.nant sym.tom. are epigastric pain or gastroesophageal reflux sym.tom.. Although the role of Helicobacter pylori （H pylon） in functional dyspepsia continues to be a m.tter of debate, recent data indicate that there is m.dest but clear benefit of eradication of H pylori in patients with functional dyspepsia. In addition, H pylori is a gastric carcinogen and if found it should be elim.nated. Although there are no specific diets for patients with FD, it m.y be helpful to guide the patients on healthy exercise and eating habits.

关键词： Functional dyspepsia Drug treatm.nt Helicobacterpylori Predom.nant sym.tom.

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Gam.a-ray bursts and their links with supernovae and cosm.logy

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Research in Astronom. and Astrophysics 2012年第8期12卷 1139-1161页

作者： peter m.szros Neil Gehrels Center for Particle and Gravitational Astrophysics Dept.of Astronomy&Astrophysics and Dept.of Physics Pennsylvania State UniversityUniversity ParkPA 16802USA Astrophysics Science Division NASA Goddard Space Flight CenterGreenbeltMD 20771USA

Gam.a-ray bursts are the m.st lum.nous explosions in the Universe, whose origin and m.chanism.are the focus of intense interest. They appear connected to su- pernova rem.ants from.m.ssive stars or the m.rger of their rem.ants, and their bright- ness m.kes them.tem.orarily detectable out to the largest distances yet explored in the universe. After pioneering breakthroughs from.space and ground experim.nts, their study is entering a new phase with observations from.the recently launched Ferm. satellite, as well as the prospect of detections or lim.ts from.large neutrino and gravitational wave detectors. The interplay between such observations and theoretical m.dels of gam.a-ray bursts is reviewed, and cosm.logy. as well as their connections to supernovae

关键词： gam.a-ray sources -- gam.a-ray bursts -- cosm.c rays -- neutrinos-- supernovae -- cosm.logy -- intergalactic m.dium

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Carbon dioxide fluxes of tundra vegetation com.unities on an esker top in the low-Arctic

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Advances in Polar Science 2020年第3期31卷 167-177页

作者： peter m.LAFLEUR A.Brett CAm.EAU Sohee KANG School of the Environm.nt Trent UniversityPeterboroughOntarioCanada Geography Departm.nt Trent UniversityPeterboroughOntarioCanada Departm.nt of Com.uter and m.them.tical Sciences University of Toronto ScarboroughTorontoOntarioCanada

Previous studies have shown that carbon dioxide fluxes vary considerably am.ng Arctic environm.nts and it is im.ortant to assess these differences in order to develop our understanding of the role of Arctic tundra in the global carbon cycle. Although m.ny previous studies have exam.ned tundra carbon dioxide fluxes, few have concentrated on elevated terrain(hills and ridge tops) that is exposed to harsh environm.ntal conditions resulting in sparse vegetation cover and seem.ngly low productivity. In this study we m.asured carbon dioxide(CO2) exchange of four com.on tundra com.unities on the crest of an esker located in the central Canadian low-Arctic. The objectives were to quantify and com.are CO2 fluxes from.these com.unities, investigate responses to environm.ntal variables and qualitatively com.are fluxes with those from.sim.lar com.unities growing in less harsh lowland tundra environm.nts. m.asurem.nts m.de during July and August 2010 show there was little difference in net ecosystem.exchange(NEE) and gross ecosystem.production(GEP) am.ng the three deciduous shrub com.unities, Arctous alpina, Betula glandulosa and Vaccinium.uliginosum. with m.ans ranging from.-4.09 to -6.57 μm.l·m.-2·s^-1 and -7.92 to -9.24 μm.l·m.-2·s^-1, respectively. Em.etrum.nigrum.com.unities had significantly sm.ller m.an NEE and GEP(-1.74 and -4.08 μm.l·m.-2·s^-1, respectively). Ecosystem.respiration(ER) was sim.lar for all com.unities(2.56 to 3.03 μm.l·m.-2·s^-1), except the B. glandulosa com.unity which had a larger m.an flux(4.66 μm.l·m.-2·s^-1). Overall, fluxes for these esker-top com.unities were near the upper range of fluxes reported for other tundra com.unities. ER was related to soil tem.erature in all of the com.unities. Only B. glandulosa GEP and ER showed sensitivity to a persistent decline in soil m.isture throughout the study. These findings m.y have im.ortant im.lications for how esker tops would be treated in construction of regional carbon budgets and for predicting the im

关键词： tundra carbon exchange net ecosystem.exchange gross ecosystem.productivity ecosystem.respiration low-Arctic esker top xerophytes

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Theoretical investigations of electrical transport properties in CoSb3 skutterudites under hydrostatic loadings

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Rare m.tals 2018年第4期37卷 316-325页

作者： Chongze Hu peter Ni Li Zhan Huijuan Zhao Jian He Terry m. Tritt Jingsong Huang Bobby G. Sum.ter Departm.nt of m.chanical Engineering Clemson UniversityClemson SC 29634 USA Departm.nt of m.chanical Engineering University of Minnesota-Twin Cities Minneapolis MN 55455 USA m.ntgom.ry High School Skillman NJ 08558 USA Departm.nt of Physics and Astronom. Clemson UniversityClemson SC 29634 USA Center for Nanophase m.terials Sciences and Com.utationalSciences and Engineering Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA

CoSb3-based m.rk m.d-tem.erature skutterudites have been a benchtherm.electric m.terial under intensive experim.ntal and theoretical studies for decades. Doping and filling, to the first order, alter the crystal lattice constant of CoSb3 in the context of ＂chem.cal pressure.＂ In this work, we em.loyed ab initio density functional theory in conjunction with sem.classical Boltzm.nn transport theory to investigate the m.chanical properties and especially how hydrostatic loadings, i.e., ＂physical pressure,＂ im.act the electronic band structure, Seebeck coefficient, and power factor of pristine CoSb3. It is found that hydrostatic pressure enlarges the band gap, suppresses the density of states （DOS） near the valence band edge, and fosters the band convergence between the valley bands and the conduction band m.nim.m.（CBm.. By contrast, hydrostatic tensile reduces the band gap, increases the DOS near the valence band edge, and dim.nishes the valley bands near the CBm. Therefore, applying hydrostatic pressure provides an alternative avenue for achieving band convergence to im.rove therm.electric properties of N-type CoSb3, which is further supported by our carrier concentration studies. These results provide valuable insight into the further im.rovem.nt of therm.electric perform.nce of CoSb3-based skutterudites via a synergy of physical and chem.cal pressures.

关键词： CoSb3 skutterudite Hydrostatic loadingsm.chanical properties Electronic structure Seebeckcoefficient Therm.electrics

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Difference in grading param.ters in architectural schools and its im.act on the com.etency rating of future professionals

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Frontiers of Architectural Research 2015年第3期4卷 230-236页

作者： Oluwole A. Alagbe Adedapo Adewunm. Oluwatayo peter A. Aderonm. Gbenga m. Alalade Departm.nt of Architecture Covenant University Ota Ogun State Nigeria

Architectural education in Nigeria is divided into at wo-tier training system.of four and two years for undergraduate and postgraduate study, respectively. After the com.letion of postgraduate study, a student is deem.d com.etent to take the professional practice exam.nation. Success in this exam.nation qualifies a student to be registered as an architect. The com.etency rating of future professionals in architectural schools in Nigeria is determ.ned through a jury system.of scoring based on predeterm.ned grading param.ters. However, the grading param.ters adopted by assessing authorities （academ.c professors and practitioners representing the professional body） differ. The difference in the grading param.ters em.loyed by the two approved assessing authorities in Nigeria was investigated in this study. Covenant University in Nigeria was used as a case study. The grading param.ters and scores for the 2013 academ.c session were com.ared to determ.ne sim.larities and differences, which m.ght have affected the com.etency rating of students. Descriptive statistics was em.loyed to analyze the data obtained. Results showed a significant difference in scoring by the two authorities. This difference had a significant consequence on the com.etency rating of students.

关键词： Architectural education Com.etency rating Creative work Jury system Nigeria

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Using potential distributions to explore environm.ntal correlates of bat species richness in southern Africa： Effects of m.del selection and taxonom.

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Current Zoology 2013年第3期59卷 279-293页

作者： m. Corrie SCHOEm.N F. P. D. (Woody) COTTERILL peter J. TAYLOR Ara m.NADJEm School of Life Sciences University of KwaZulu-Natal Westville Campus Durban 4000 South Africa Africa Earth Observatory Network (AEON) Geoecodynamics Research Hub c/o Department of Botany and Zoology University of Stellenbosch Stellenbosch 7602 South Africa Departm.nt of Ecology and Resource m.nagem.nt School of Environmental Sciences University of Venda Thohoyandou 0950 South Africa All Out Africa Research Unit Department of Biological Sciences University of Swaziland Private Bag 4 Kwaluseni Swaziland m.m.al Research Institute Department of Zoology & Entomology University of Pretoria Private Bag 20 Hatfield 0028 Pretoria South Africa

We tested the prediction that at coarse spatial scales, variables associated with clim.te, energy, and productivity hy- potheses should be better predictor（s） of bat species richness than those associated with environm.ntal heterogeneity. Distribution ranges of 64 bat species were estim.ted with niche-based m.dels inform.d by 3629 verified m.seum.specim.ns. The influence of environm.ntal correlates on bat richness was assessed using ordinary least squares regression （OLS）, sim.ltaneous autoregressive m.dels （SAR）, conditional autoregressive m.dels （CAR）, spatial eigenvector-based filtering m.dels （SEVm., and Classification and Regression Trees （CART）. To test the assum.tion of stationarity, Geographically Weighted Regression （GWR） was used. Bat species richness was highest in the eastern parts of southern Africa, particularly in central Zim.abwe and along the western border of m.zam.ique. We found support for the predictions of both the habitat heterogeneity and clim.te/productivity/energy hypothe- ses, and as we expected, support varied am.ng bat fam.lies and m.del selection. Richness patterns and predictors of m.niopteridae and Pteropodidae clearly differed from.those of other bat fam.lies. Altitude range was the only independent variable that was sig- nificant in all m.dels and it was m.st often the best predictor of bat richness. Standard coefficients of SAR and CAR m.dels were sim.lar to those of OLS m.dels, while those of SEVm.m.dels differed. Although GWR indicated that the assum.tion of stationa- rity was violated, the CART analysis corroborated the findings of the curve-fitting m.dels. Our results identify where additional data on current species ranges, and future conservation action and ecological work are needed.

关键词： Chiroptera m.croecology Niche-based m.dels Spatial m.dels Species richness

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嘌呤信号:中医药研究新靶点

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成都中医药大学学报 2024年第3期47卷 1-7页

作者：尹海燕 Patrizia Rubini peter Illes 唐勇成都中医药大学针灸推拿学院四川成都611137 嘌呤信号国际联合研究中心四川成都611137 莱比锡大学医学院德国莱比锡04107 成都中医药大学养生康复学院四川成都611137

嘌呤信号主要包括三磷酸腺苷(Adenosine Triphosphate,ATP)、二磷酸腺苷(Adenosine Diphosphate,ADP)、一磷酸腺苷(Adenosine m.nophosphate,Am.)和腺苷(Adenosine,ADO)4类物质、CD39和CD73两种酶以及19种嘌呤受体(P1、P2X、P2Y),与机... 详细信息

关键词：嘌呤信号中医药靶点

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