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排序方式: 共有118条查询结果,搜索用时 15 毫秒
51.
This paper reports on an experimental study of the adhesive contact of a single microscopic (about 300 μm) elastomer sphere compressed between two smooth parallel glass platens at small imposed deformations. An experimental arrangement that allows the simultaneous measurement of the compressive displacements and the reaction forces is described. A number of interesting phenomena, including the pull-off separation and the “jump” contact phenomena of the microsphere and the moving platen supported by a cantilever, are shown in the experimental force-displacement curve of a loading and unloading cycle. The pull-off forces are demonstrated to not depend upon the applied dimensionless approach (compressive displacement/initial particle diameter), while they increase with the increasing rate at which the interfaces are separated. The predictions of an established contact mechanical adhesive theory, Johnson–Kendall–Roberts (JKR) theory, in which the influence of the surface energy on the contact has been taken into account, are in good agreement with these experimental results. An application of the JKR analysis to the pull-off force provides a reasonable estimate of the interfacial free energy of the contact. 相似文献
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Fantuzzi A Meharenna YT Briscoe PB Sassone C Borgia B Gilardi G 《Chemical communications (Cambridge, England)》2006,(12):1289-1291
In this work the catalytic properties of a cytochrome P450 immobilised onto an electrode surface are improved by means of the molecular Lego approach. 相似文献
56.
Dugger M Ball JP Collins P Pasyuk E Ritchie BG Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Asryan G Audit G Avakian H Bagdasaryan H Baillie N Baltzell NA Barrow S Batourine V Battaglieri M Beard K Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Bianchi N Biselli AS Bonner BE Bouchigny S Boiarinov S Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Burkert VD Butuceanu C Calarco JR Careccia SL Carman DS Carnahan B Chen S Cole PL Coleman A Coltharp P Cords D 《Physical review letters》2006,96(6):062001
Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process. 相似文献
57.
Zhu LS Lapko VN Lee JW Basir YJ Kafonek C Olsen R Briscoe C 《Rapid communications in mass spectrometry : RCM》2006,20(22):3421-3426
Bisphosphonates are extremely hydrophilic and structurally similar to many endogenous phosphorylated compounds, making their selective extraction from serum or urine very challenging. Many bisphosphonates lack strong chromophores for sensitive UV or fluorescence detection. We report here the first general approach to enable sensitive and selective quantitation of N-containing bisphosphonates by liquid chromatography/tandem mass spectrometry (LC/MS/MS) following derivatization with diazomethane. The novelty of the strategy lies in performing the derivatization on silica-based anion-exchange sorbents as an integrated step in the sample purification by solid-phase extraction (SPE). The 'on-cartridge' reaction with diazomethane not only led to higher efficiency of derivatization, but also enabled a more discriminatory recovery of the drug's derivatives. The derivatized bisphosphonates demonstrated improved chromatographic separation and increased sensitivity of the detection. The general applicability of the approach was demonstrated by validation of bioanalytical methods for risedronate and alendronate in human serum and urine. Sensitivity was achieved at the pg/mL level with merely 100-200 microL of sample. 相似文献
58.
S. Schumann B. Boillat E. J. Downie P. Aguar-Bartolomé J. Ahrens J. R. M. Annand H. J. Arends R. Beck V. Bekrenev A. Braghieri D. Branford W. J. Briscoe J. W. Brudvik S. Cherepnya R. Codling P. Drexler L. V. Fil’kov D. I. Glazier R. Gregor E. Heid D. Hornidge O. Jahn V. L. Kashevarov R. Kondratiev M. Korolija M. Kotulla D. Krambrich B. Krusche M. Lang V. Lisin K. Livingston S. Lugert I. J. D. MacGregor D. M. Manley M. Martinez-Fabregate J. C. McGeorge D. Mekterovic V. Metag B. M. K. Nefkens A. Nikolaev R. Novotny M. Ostrick R. O. Owens P. Pedroni A. Polonski S. N. Prakhov J. W. Price G. Rosner M. Rost T. Rostomyan D. Sober A. Starostin I. Supek C. M. Tarbert A. Thomas M. Unverzagt Th. Walcher D. P. Watts F. Zehr 《The European Physical Journal A - Hadrons and Nuclei》2010,43(3):269-282
The reaction γp → pπ 0γ′ has been measured with the Crystal Ball/TAPS detectors using the energy-tagged photon beam at the electron accelerator facility MAMI-B. Energy and angular differential cross-sections for the emitted photon γ′ and angular differential cross-sections for the π0 have been determined with high statistics in the energy range of the Δ+ (1232)-resonance. Cross-sections and the ratio of the cross-section to the nonradiative process γp → pπ 0 are compared to theoretical reaction models, having the anomalous magnetic moment κ Δ as free parameter. As the shape of the experimental distributions is not reproduced in detail by the model calculations, currently no extraction of κ Δ is feasible. 相似文献
59.
Baghdasaryan H Weinstein LB Laget JM Adhikari KP Aghasyan M Amarian M Anghinolfi M Avakian H Ball J Battaglieri M Bedlinskiy I Bennett RP Berman BL Biselli AS Bookwalter C Briscoe WJ Brooks WK Bültmann S Burkert VD Carman DS Crede V D'Angelo A Daniel A Dashyan N De Vita R De Sanctis E Deur A Dey B Dickson R Djalali C Dodge GE Doughty D Dupre R Egiyan H El Alaoui A El Fassi L Eugenio P Fegan S Gabrielyan MY Gilfoyle GP Giovanetti KL Gohn W Gothe RW Griffioen KA Guidal M Guo L Gyurjyan V 《Physical review letters》2010,105(22):222501
We have measured the 3He(e,e' pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p(tot). For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low p(tot) and rises to approximately 0.5 at large p(tot). This shows the dominance of tensor over central correlations at this relative momentum. 相似文献
60.
Avakian H Bosted P Burkert VD Elouadrhiri L Adhikari KP Aghasyan M Amaryan M Anghinolfi M Baghdasaryan H Ball J Battaglieri M Bedlinskiy I Biselli AS Branford D Briscoe WJ Brooks W Carman DS Casey L Cole PL Collins P Crabb D Crede V D'Angelo A Daniel A Dashyan N De Vita R De Sanctis E Deur A Dey B Dhamija S Dickson R Djalali C Dodge G Doughty D Dupre R El Alaoui A Eugenio P Fegan S Fersch R Forest TA Fradi A Gabrielyan MY Gavalian G Gevorgyan N Gilfoyle GP Giovanetti KL Girod FX Gohn W Gothe RW 《Physical review letters》2010,105(26):262002
We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ? have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2? single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton. 相似文献