Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Implications Of Ignoring Electrostatic Interaction On Simulated And Experimental Protein Titration Curves

[No abstract available]291135141Linderstrom-Lang, (1924) Rec. Trav. Lab. Carlsberg, 15 (7)Cannan, (1942) Chem. Rev., 30, p. 395Kenchington, Ward, (1954) Biochem. J., 58, p. 202Levy, (1958) C.R. Trav. Lab. Carlsberg, 30, p. 291Godinho, Aleixo, (1981) Anal. Biochem., 112, p. 323Kaarsholm, Schack, Ionization Behavior of Papaya Peptidase A and Its Succinylated Derivative. (1984) Acta Chemica Scandinavica, 38 B, p. 225Marini, Martin, Evaluation of the Electrostatic Interaction Parameter on a Simulated Protein Titration Curve (1980) Analytical Letters, 13 (2 B), p. 93Aleixo, Godinho, da Costa, (1992) Anal. Chim. Acta, 257, p. 35Godinho, de Souza, Aleixo, Ivaska, (1988) J. Assoc. Off. Anal. Chem., 71, p. 1028Canfield, (1963) J. Biol. Chem., 238, p. 2698Nisbet, Saundry, Moir, Fothergill, Fothergill, (1981) Eur. J. Biochem., 115, p. 335Inada, (1961) J. Biochem. (Tokyo), 49, p. 217Tojo, Hamaguchi, Imanishi, Amano, (1966) J. Biochem. (Tokyo), 60, p. 13

Especiação dinâmica de metais traço em ambiente aquático usando cronopotenciometria de redissolução anódica

International audienceDYNAMIC SPECIATION OF TRACE METALS IN AQUATIC ENVIRONMENT USING ANODIC STRIPPING CHRONOPOTENTIOMETRY. The contamination of natural environments by trace metals has several adverse effects on human health, which is mainly due to the high toxicity, persistence and reactivity of these species in the environment. To understand the bioavailability of trace metals, it is necessary to know the speciation in equilibrium and the dynamic behavior of the system. In this context, the present work aims to present a bibliographic review about the potentialities of the Stripping Chronopotentiometry (SCP) and Stripping Chronopotentiometry at Scanned Deposition Potential (SSCP) in the study of dynamic trace metal speciation. These techniques have low detection limits and do not suffer interference due to the adsorption of organic matter on the surface of the working electrode. Coupling these techniques with the Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) enables simultaneous determination of free ions, complexation equilibrium constants and diffusion coefficients of the complexes, thus providing information on the dynamic and heterogeneity of the metal complexes in the presence of macromolecules or particles. In this paper we will present the theory of dynamic speciation of trace metals, a detailed description of how to use the techniques to obtain this information, and examples of application in model systems and natural samples

Characterization of PMMA-b-PDMAEMA aggregates in aqueous solutions

International audienceDiblock amphiphilic copolymers form aggregates in some solvents. Such aggregates exhibit different morphologies, depending mainly on the polar/apolar block ratios. Aggregation of copolymers with polar block excess leads to micelle-like aggregates, known as polymeric micelles, which can be used as vehicles for drug and gene delivery, water decontamination, and catalysis. Here, we synthesized by RAFT polymerization three different polymers namely [dimethyl 2-(aminoethyl) methacrylate] (PDMAEMA), poly (methyl methacrylate) (PMMA) copolymers, and PDMAEMA-block-PMMA and characterized their aggregates by NMR spectroscopy and pH titrations. We investigated correlations between their chemical structure, aggregation behavior, protonation degree, and chain conformation in the corona. Decreased amine protonation in the copolymers reduced the electrostatic repulsion, and the apparent pKa of the amino groups approached that of isolated amine. These effects increased compactness and sizes of the polymers and their aggregates at higher pH as reflected by the increased NMR line widths