3,253 research outputs found
Heavy Quarkonia from Classical SU(3) Yang-Mills Configurations
A generalized Cho-Faddeev-Niemi ansatz for SU(3) Yang-Mills is investigated.
The corresponding classical field equations are solved for its simplest
parametrization. From these solutions it is possible to define a confining
central non-relativistic potential used to study heavy quarkonia. The
associated spectra reproduces the experimental spectra with an error of less
than 3% for charmonium and 1% for bottomonium. Moreover, the recently
discovered new charmonium states can be accomodate in the spectra, keeping the
same level of precision. The leptonic width show good agreement with the recent
measurements. The charmonium and bottomonium E1 electromagnetic transitions
widths are computed and compared with the experimental values.Comment: 3 pages. Talk at QNP06, 5th-10th June, Madrid, Spai
Charmonium and Bottomonium from Classical SU(3) Gauge Configurations
The charmonium and bottomonium spectra computed from a potential defined from
a single gauge configuration, obtained from solving the classical field
equations, is discussed. The theoretical spectra shows good agreement with the
measured states.
A discussion of possible interpretations, within the same non-relativistic
potential model, for the new charmonia states X(3872), and
Y(4260) is performed. In particular, we give predictions for electromagnetic E1
transitions for various scenarios.Comment: Talk given at "Quark Confinement and the Hadron Spectrum VII", Ponta
Delgada, Sao Miguel, Azores, Portugal, Sept. 2-7, 200
The antioxidant activity of polysaccharides: a structure-function relationship overview
Over the last years, polysaccharides have been linked to antioxidant effects using both in vitro chemical and biological models. The reported structures, claimed to act as antioxidants, comprise chitosan, pectic polysaccharides, glucans, mannoproteins, alginates, fucoidans, and many others of all type of biological sources. The structural features linked to the antioxidant action include the polysaccharide charge, molecular weight, and the occurrence of non-carbohydrate substituents. The establishment of structure/function relationships can be, however, biased by secondary phenomena that tailor polysaccharides behavior in antioxidant systems. In this sense, this review confronts some basic concepts of polysaccharides chemistry with the current claim of carbohydrates as antioxidants. It critically discusses how the fine structure and properties of polysaccharides can define polysaccharides as antioxidants. Polysaccharides antioxidant action is highly dependent on their solubility, sugar ring structure, molecular weight, occurrence of positive or negatively charged groups, protein moieties and covalently linked phenolic compounds. However, the occurrence of phenolic compounds and protein as contaminants leads to misleading results in methodologies often used for screening and characterization purposes, as well as in vivo models. Despite falling in the concept of antioxidants, the role of polysaccharides must be well defined according with the matrices where they are involved.publishe
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