Improved Measurement of the dˉ/uˉ\bar d / \bar u Asymmetry in the Nucleon Sea

Measurements of the ratio of Drell-Yan yields from an 800 \rm{GeV/c} proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of anti-down ($\bar{d}$) to anti-up ($\bar{u}$) quark distributions in the proton sea is determined over a wide range in Bjorken-$x$. These results confirm previous measurements by E866 and extend them to lower $x$. From these data, $(\bar{d}-\bar{u})$ and $\int(\bar{d}-\bar{u})dx$ are evaluated for $0.015<x<0.35$. These results are compared with parameterizations of various parton distribution functions, models and experimental results from NA51, NMC, and HERMES.Comment: 17 pages, 15 figure

Dendrimers as anti-inflammatory agents

Dendrimers constitute an intriguing class of macromolecules which find applications in a variety of areas including biology. These hyperbranched macromolecules with tailored backbone and surface groups have been extensively investigated as nanocarriers for gene and drug delivery, by molecular encapsulation or covalent conjugation. Dendrimers have provided an excellent platform to develop multivalent and multifunctional nanoconjugates incorporating a variety of functional groups including drugs which are known to be anti-inflammatory agents. Recently, dendrimers have been shown to possess anti-inflammatory properties themselves. This unexpected and intriguing discovery has provided an additional impetus in designing novel active pharmaceutical agents. In this review, we highlight some of the recent developments in the field of dendrimers as nanoscale anti-inflammatory agents

Hyperbranched poly(ether ketones): Manipulation of structure and physical properties

Hyperbranched poly(ether ketones), with a variety of chain end functional groups and controllable degrees of branching, are prepared by the polymerization of AB, AB, and AB monomers. It is found that the choice of A and B, or the incorporation of dendritic and linear units into the AB monomer structure, dramatically affects the degree of branching. Depending on the structure of the monomer unit, degrees of branching ranging from 15 to 71% can be obtained. For determining the degree of branching for fluoro-terminated hyperbranched poly(ether ketones), a new technique based on F NMR has been developed. Evaluation of the physical properties of the hyperbranched poly(ether ketones) with different degrees of branching has shown that thermal properties are independent of macromolecular architecture but depend heavily on the nature of the chain end functional groups, with glass transition temperatures ranging from 97 to 290°C. The solubility of the hyperbranched poly(ether ketones) is also shown to depend heavily on the nature of the chain ends, and by varying the chain ends, poly(ether ketones) soluble in either hexane or aqueous solutions could be obtained. The water-soluble derivatives were shown to act as unimolecular micelles

New polymer synthesis by nitroxide mediated living radical polymerizations

No abstract

Hyperbranched poly(ethylene glycol)s: A new class of ion-conducting materials

A new concept for the synthesis of hyperbranched macromolecules involving the use of AB macromonomers containing linear oligomeric units is introduced. This methodology is used for the preparation of a series of novel hyperbranched poly(ethylene glycol) derivatives containing linear poly(ethylene glycol) units of varying lengths and 3,5-dioxybenzoate branching units. An interesting feature of the hyperbranched poly(ethylene glycol) derivatives is their lack of crystallinity, which is used in the design of a new class of polyelectrolyte materials. The dependence of the ionic conductivity on temperature and the concentration of added lithium cations for these novel hyperbranched macromolecules is reported

Intramolecular cyclization in hyperbranched polyesters

The effect of monomer structure and catalyst on the synthesis of hyperbranched polyesters based on 4,4-(4′-hydroxyphenyl)pentanoic acid has been examined. The nature of the ester group and the catalyst have a significant effect on the molecular weight of the hyperbranched polyester but do not effect the degree of branching for these materials. The fate of the single ester group at the focal point of these hyperbranched macromolecules is probed by the synthesis and polymerization of C labeled methyl 4,4-(4′-hydroxyphenyl)pentanoate. Comparison of the molecular weights determined by H- or C-NMR spectra with those determined by osmometry suggest that intramolecular cyclization does not occur to a significant extent in these systems