Search

NEW YORK: The ongoing negotiations between NTT Mobile Communications Network Inc. (NTT DoCoMo) and International Business Machines Corp. over a possible alliance in developing computer systems for next-generation mobile phone [...]

NEW YORK: NTT Mobile Communications Network Inc. (NTT DoCoMo) and International Business Machines Corp. of the United States are currently negotiating a tie-up in next-generation mobile-phone services, slated to begin [...]

Colored crosslinked polyacrylic acid can be synthesized for use as a teaching material for showing convection currents in heated water in chemistry classes. A radical initiator is required for polymerization of acrylic acid and ammonium peroxidisulfate with N, N, N', N'-tetraethylenediamine (TMEDA) is a convenient water-soluble initiator. The degree of cross-linking reduces the ability of the polymer to swell, but to be insoluble in water the chains must be cross-linked. To get a gel with density similar to that of water is important. Using very small amounts of inexpensive N,N'-methylenebisacrylamide (MBAA) as a cross-linking agent is effective. To demonstrate water convection currents pieces of polymer are placed in a beaker of water which is warmed with a spirit lamp and then cooled so that the polymer gel goes up and down.