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Tiny Amount (tiny + amount)
Selected AbstractsScale-up development of high-performance polymer matrix for DNA sequencing analysisELECTROPHORESIS, Issue 19 2006Fen Wan Abstract Linear polyacrylamide (LPA) has been widely used as a replaceable separation matrix in CE. An increase in the molecular weight of the separation medium favors the separation of larger DNA fragments. In order to obtain ultrahigh-molecular-weight (UHMW) LPA, a "frozen" method was developed to synthesize the LPA homopolymer. This approach has three major advantages when compared with other existing routes of LPA synthesis: (i),long LPA chains could be obtained easily, with their average molecular weight (MW) being in the high 10,MDa range; (ii),the desired MW could be adjusted over a broad range by controlling the temperature and the concentration of initiators during synthesis; (iii),the product solution contains only a tiny amount of impurity besides the solvent and LPA. Both static and dynamic laser light scattering measurements were carried out to characterize the synthesized LPA in the buffer solution. The DNA sequencing matrix prepared from LPA using this method was studied and the results were compared with the newly developed commercial product POP7 from Applied Biosystems. It should be noted that this approach can be applied to synthesize other water-soluble polymers, resulting in UHMW products because the chain transfer constant is smaller at lower temperatures. [source] Exothermic thermal reaction of dopamine with 3,5-dinitrobenzoic acidJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2003Yoshikatsu Ito Abstract Pyrolysis of the crystalline 1,:,1 molecular complex DA,dnba, which was prepared from cocrystallization of dopamine (DA) and 3,5-dinitrobenzoic acid (dnba), was studied. This cocrystal decomposed violently at the melting-point, leading to the formation of a black solid along with a tiny amount of 3-amino-5-nitrobenzoic acid (1). The pyrolysis reaction was followed by differential scanning calorimetry (DSC) and one large exothermic peak was observed at the decomposition temperature. In view of the DSC patterns for cocrystal DA,dnba and other compounds, it seems that both a catechol moiety and an amino group of DA in addition to a strong electron acceptor such as dnba are required for the appearance of the exothermic peak. On the basis of (a) elemental analysis of the black solid and (b) other pyrolysis experiments for cocrystals PA,dnba (PA: ,-phenylethylamine), BA,dnba (BA: benzylamine), DMDA,dnba (DMDA: O,O,-dimethyldopamine) and DHBA,dnba (DHBA: 3,4-dihydroxybenzylamine), it is assumed that the black solid was formed mainly through elimination of more than one molecule of water from one molecule of DA,dnba. Copyright © 2003 John Wiley & Sons, Ltd. [source] Dispersion-Polymerized Carbon Nanotube/Poly(methyl methacrylate) Composite Particles and their Electrorheological CharacteristicsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 5 2007Sung Tae Kim Abstract An in situ dispersion polymerization method was adopted to synthesize particulate composites of MWNTs and PMMA, mainly for the investigation of their electrorheological characteristics. The morphology of the PMMA microparticles synthesized in the presence of the MWNTs was examined by both SEM and TEM, showing that the MWNTs were not only grafted onto the surface of the PMMA microbeads, but were also embedded inside the synthesized microbeads. The synthesized MWNT/PMMA particulate composites were also characterized by zeta-potential measurements and TGA for electric and thermal stability studies, respectively. A suspension of the MWNT/PMMA microparticles dispersed in silicone oil was found to show enhanced electrorheological properties on the increase of shear stresses when subjected to an external electric field, exhibiting high yield stresses despite the tiny amount of the MWNT associated. [source] Optimization of Electrochemical and Peroxide-Driven Oxidation of Styrene with Ultrathin Polyion Films Containing Cytochrome P450cam and MyoglobinCHEMBIOCHEM, Issue 1 2003Bernard Munge Abstract The catalytic and electrochemical properties of myoglobin and cytochrome P450camin films constructed with alternate polyion layers were optimized with respect to film thickness, polyion type, and pH. Electrochemical and hydrogen peroxide driven epoxidation of styrene catalyzed by the proteins was used as the test reaction. Ionic synthetic organic polymers such as poly(styrene sulfonate), as opposed to SiO2nanoparticles or DNA, supported the best catalytic and electrochemical performance. Charge transport involving the iron heme proteins was achieved over 40,320 nm depending on the polyion material and is likely to involve electron hopping facilitated by extensive interlayer mixing. However, very thin films (ca. 12,25 nm) gave the largest turnover rates for the catalytic epoxidation of styrene, and thicker films were subject to reactant transport limitations. Classical bell-shaped activity/pH profiles and turnover rates similar to those obtained in solution suggest that films grown layer-by-layer are applicable to turnover rate studies of enzymes for organic oxidations. Major advantages include enhanced enzyme stability and the tiny amount of protein required. [source] | ||||||||||