Site-Specific Functionalization of Hyperbranched Polymers Using ``Click'' Chemistry

Different strategies for functionalization of the core region and periphery of core-shell type hyperbranched polymers (HBP) using the ``click'' reaction have been explored. For achieving periphera functionalization, an AB(2) + A-R-1 + A-R-2 type copolymerization approach was used, where A-R-1 is heptaethylene glycol monomethyl ether (HPEG-M) and A-R-2 is tetraethylene glycol monopropargyl ether (TEG-P). A very small mole fraction of the propargyl containing monomer, TEG-P, was used to ensure that the water-solubility of the hyperbranched polymer is minimally affected. Similarly, to incorporate propargyl groups in the core region, a new propargyl group bearing B-2-typ monomer was designed and utilized in an AB(2) + A(2) + B-2 + A-R-1 type copolymerization, such that the total mole fraction of B-2 + A(2) is small and their mole-ratio is 1: 1. Further, using a combination of both the above approaches, namely AB(2) + A(2) + B-2 + A-R-1 + A-R-2, hyperbranched structures that incorporate propargyl groups both at theperiphery and within the core were synthesized. Since the AB(2) monomer carries a hexamethylene spacer (C-6) and the periphery is PEGylated all the derivatized polymers form core-shell type structures in aqueous solutions. Attempts were made to ascertain and probe the location of the propargyl groups in these HBP's, by ``clicking'' azidomethylpyrene, onto them. However, the fluorescence spectra of aqueous solutions of the pyrene derivatized polymers were unable to discriminate between the various locations, possibly because the relatively hydrophobic pyrene units insert themselves into the core region to minimize exposure to water.

Bearing capacity of square footings on geosynthetic reinforced sand

The results from laboratory model tests and numerical simulations on square footings resting on sand are presented. Bearing capacity of footings on geosynthetic reinforced sand is evaluated and the effect of various reinforcement parameters like the type and tensile strength of geosynthetic material, amount of reinforcement, layout and configuration of geosynthetic layers below the footing on the bearing capacity improvement of the footings is studied through systemati model studies. A steel tank of size 900 x 900 x 600 mm is used for conducting model tests. Four types of grids, namely strong biaxial geogrid, weak biaxial geogrid, uniaxial geogrid and a geonet, each with different tensile strength, are used in the tests. Geosynthetic reinforcement is provided in the form of planar layers, varying the depth of reinforced zone below the footing, number of geosynthetic layers within the reinforced zone and the width of geosynthetic layers in different tests. Influence of all these parameters on the bearing capacity improvement of square footing and its settlement is studied by comparing with the test on unreinforced sand. Results show that the effective depth of reinforcement is twice the width of the footing and optimum spacing of geosynthetic layers is half the width of the footing. It is observed that the layout and configuration of reinforcement play a vital role in bearing capacity improvement rather than the tensile strength of the geosynthetic material. Experimental observations are supported by the findings from numerical analyses.

Ilse Goldschmidt nee Molling with her sons Ernest and Frank Goldschhmidt on her 80th birthday; Laguna Hills, California.

Left to Right: Ernest Goldschmidt, Ilse Goldschmidt born Molling, and Frank Goldschmidt. The picture was taken on the occasion of Ilse's 80th birthday party 22 Dec 1989 Laguna Hills, CA.

Lotte Stern and Dr. Alfred Stern with Otto Wallerstein, a relative of Lotte's father; Berkeley, California.

From left to right: Lotte Stern, Otto Wallerstein, Alfred Stern; Photograph taken shortly after arrival in Berkeley, California

Ilse Goldschmidt nee Molling with her sons Ernest and Frank Goldschhmidt on her 80th birthday; Laguna Hills, California.

Left to Right: Ernest Goldschmidt, Ilse Goldschmidt born Molling, and Frank Goldschmidt. The picture was taken on the occasion of Ilse's 80th birthday party 22 Dec 1989 Laguna Hills, CA.

Albert Einstein; California Portraits; Men

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Albert Einstein writing; California Portraits; Men

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Albert and Elsa Einstein on the beach with Walter Adams; Santa Barbara, California Portraits; Groups

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Lotte Stern and Dr. Alfred Stern with Otto Wallerstein, a relative of Lotte's father; Berkeley, California.

From left to right: Lotte Stern, Otto Wallerstein, Alfred Stern; Photograph taken shortly after arrival in Berkeley, California

50th wedding anniversary party of Paul Goldschmidt and Ilse nee Molling; Laguna Hills, California.

left to right: Margot Molling, Ilse Molling, Adolf Molling, Paul Goldschmidt (husband of Ilse Molling)

Wear characteristics and bearing performance of aluminium-mica particulate composite material

Some tribological properties of a mica-dispersed Al-4%Cu-1.5%Mg alloy cast by a conventional foundry technique are reported. The effect of mica dispersion on the wear rate and journal bearing performance of the matrix alloy was studied under different pressures and under different interface friction conditions. The dispersion of mica was found (a) to increase the wear rate of the base alloy, (b) to decrease the temperature rise during wear and (c) to improve the ability of the alloy to resist seizure.

Ernst Weill seated on a boat dock; Santa Barbara, California Portraits Men

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