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First measurement of the left-right cross section asymmetry in Z boson production by e+e- collisions
Abe K Abt I Acton PD Adolphsen CE Agnew G Alber C Alzofon DF Antilogus P Arroyo C Ash WW Ashford V Astbury A Aston D Au Y Axen DA Bacchetta N Baird KG Baker W Baltay C Band HR Baranko G Bardon O Barrera F Battiston R Bazarko AO Bean A Beer G Belcinski RJ Bell RA Ben-David R Benvenuti AC Berger R Berridge SC Bethke S Biasini M Bienz T Bilei GM Bird F Bisello D Blaylock G Blumberg R Bogart JR Bolton T Bougerolle S Bower GR Boyce RF Brau JE Breidenbach M Browder TE Bugg WM Burgess B Burke D 《Physical review letters》1993,70(17):2515-2520
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Barrera C Herrera AP Bezares N Fachini E Olayo-Valles R Hinestroza JP Rinaldi C 《Journal of colloid and interface science》2012,377(1):40-50
The size, charge, and stability of colloidal suspensions of magnetic nanoparticles with narrow size distribution and grafted with poly(ethylene glycol)-silane of different molecular weights were studied in water, biological buffers, and cell culture media. X-ray photoelectron spectroscopy provided information on the chemical nature of the nanoparticle surface, indicating the particle surfaces consisted of a mixture of amine groups and grafted polymer. The results indicate that the exposure of the amine groups on the surface decreased as the molecular weight of the polymer increased. The hydrodynamic diameters correlated with PEG graft molecular weight and were in agreement with a distributed density model for the thickness of a polymer shell end-grafted to a particle core. This indicates that the particles obtained consist of single iron oxide cores coated with a polymer brush. Particle surface charge and hydrodynamic diameter were measured as a function of pH, ionic strength, and in biological buffers and cell culture media. DLVO theory was used to analyze the particle stability considering electrostatic, magnetic, steric, and van der Waals interactions. Experimental results and colloidal stability theory indicated that stability changes from electrostatically mediated for a graft molecular weight of 750 g/mol to sterically mediated at molecular weights of 1000 g/mol and above. These results indicate that a graft molecular weight above 1000 g/mol is needed to produce particles that are stable in a wide range of pH and ionic strength, and in cell culture media. 相似文献
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Francisco J. Burguillo Javier Martin Inmaculada Barrera William G. Bardsley 《Computational Biology and Chemistry》2010,34(3):184-192
With the proliferation of related microarray studies by independent groups, a natural approach to analysis would be to combine the results across studies. In this article, we address a meta-analysis of the gene expression data on imatinib resistance in chronic myelogenous leukemia. First, an analysis of the overlapping among 6 published studies revealed that only 3 genes were coincident between 2 studies. A later reprocessing using different methods on 4 publicly available datasets revealed that 2 extra genes were overlapped between two sets. Both poor overlappings may be due to large differences in the sample source, the microarray platforms used, and a small difference in gene expression between the imatinib non-responder and responder patients. A search of common genes inside 4 public datasets afforded 404 well defined genes. Nevertheless, this necessary condition for meta-analysis caused the loss of many genes of possible interest. The expression signals of the common genes in the four datasets were reanalyzed using three summary statistical methods for combining quantitative information: Fisher, Stouffer and effect-size. Taking the three methods together and using an FDR < 0.10 threshold, a gene-list with 33 differentially expressed genes was found. Considering all the reanalysis approaches used in this work, a final gene-list with 38 differentially expressed genes is reported. Despite the important limitations to this microarray meta-analysis, the presented procedures and integrated gene-list may have some potential value as regards imatinib resistance in CML patients since it is the first attempt to integrate evidence about gene-lists in this area. 相似文献
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Miller TS Ebejer N Güell AG Macpherson JV Unwin PR 《Chemical communications (Cambridge, England)》2012,48(60):7435-7437
The electrochemical properties of the closed ends and sidewalls of pristine carbon nanotube forests are investigated directly using a nanopipet electrochemical cell. Both are shown to promote fast electron transfer, without any activation or processing of the carbon nanotube material required, in contrast to the current model in the literature. 相似文献
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A. Barrera J.A. Montoya P. del Angel J. Navarrete M.E. Cano F. Tzompantzi A. López-Gaona 《Journal of Physics and Chemistry of Solids》2012,73(8):1017-1025
The surface properties of Pd and Pd–Pt catalysts supported on binary ZrO2–WOx and ternary ZrO2–Al2O3–WOx oxides prepared by the sol–gel method were studied. Special attention was paid to the study of the texture of the catalysts as well as the chemical state of tungstated zirconia and tungstated zirconia promoted with alumina in the palladium catalysts. The catalysts were tested in the isomerization of n-hexane and were characterized by N2 physisorption, XRD, TPR, Raman spectroscopy, XPS and FT-IR of adsorbed pyridine. The catalysts had bimodal pore size distributions with mesopores in the range 55–70 Å and macropores of 1000 Å in diameter. The catalysts had a surface WOx coverage (4.4–6.0 W nm?2) lower than that of the theoretical monolayer (7.0 W nm?2). A lower acidity of the ternary ZrO2–Al2O3–WOx oxide as compared to the binary ZrO2–WOx oxide was found. Higher activity in the isomerisation of n-hexane was obtained in the Pd–Pt catalysts supported on ternary ZrAlW oxides prepared by sol–gel that is correlated with the coexistence on the surface of W4+ (WO2) or W0 and W6+ (Al2(WO4)3) species, ZrO2 in the tetragonal phase and a high amount of ZrOx suboxides species in a low oxidation state (Zr3+ and Zr2+). 相似文献