Morphology of oligomers and their network polymers

Summary The morphology of di (4-methacryloxyethylene carbamate toluylen-2-carbamic) esters of oligoethylene glycols (OUM) with different molecular weight, of their network polymers and of model oligomers without methacrylic groups was studied. The supermolecular structure of oligomers is found to depend on molecular weight. Globular structure is typical for low molecular weight oligomers with M_n1200. The structure of crystalline samples with M= 1600–3600 is lamellar. The latter is retained on melting. It is transformed into globular structure at a temperature much higher than the melting point. A correlation exists between the morphology of polymerizable oligomers and their network polymers. The process of network formation from oligomers is extremely complicated. Irrespective of the mechanism it is influenced by MWD, FTD, intermolecular interaction and a number of other factors. The interconnection between the morphology of polymerizable oligomers and the supermolecular structure of their crosslinked polymers has not been sufficiently studied.Information about this connection facilitates phenomenological understanding of the network formation process.Presented at the 7th IUPAC Discussion Conference Polymer Networks, Karlovy Vary, CSSR, September 1980     

Effects of glutathione-oxidizing agents on microtubule assembly and microtubule-dependent surface properties of human neutrophils

In human peripheral blood polymorphonuclear leukocytes and lymphocytes, GSH-oxidizing agents promote the movement of surface-bound concanavalin A (Con A) into caps and inhibit the assembly of microtubules (MT) that is normally induced by Con A binding. Con A capping and inhibition of MT assembly occur when GSH levels in cell suspensions are decreased by 30-70%, and return to GSH to control levels is accompanied by the appearance of cytoplasmic MT and by inhibition of the capping response with Con A. Oxidation of GSH markedly stimulates the hexose monophosphate shunt, and regeneration of GSH occurs rapidly. The data indicate that MT cannot be assembled or maintained in the face of decreased GSH levels. Thus, GSH homeostasis becomes critical during physiological events such as phagocytosis which simultaneously induce the assembly of MT and the production of agents like H2O2 that can oxidize GSH.     

Composite organic-inorganic nanoparticles (COINs) with chemically encoded optical signatures

To obtain a coding system for multiplex detection, we have developed a method to synthesize a new type of nanomaterial called composite organic-inorganic nanoparticles (COINs). The method allows the incorporation of a broad range of organic compounds into COINs to produce surface enhanced Raman scattering (SERS)-like spectra that are richer in variety than fluorescence-based signatures. Preliminary data suggest that COINs can be used as Raman tags for multiplex and ultrasensitive detection of biomolecules.     

Viability of a native isolate of Lactobacillus brevis in a fermented milky drink

The objective of this research was to test the viability of a native isolate of Lactobacillus brevis in two fermented milky drinks: a drink without prebiotic ingredient and another drink with oat flour (0.5%, p/v) as prebiotic ingredient. The viability of L. brevis was tested at 7, 14, and 21 after inoculation. Drink pH and lactic acid concentration was measured as a function of time (2, 7, 14, and 21 days after inoculation). The isolate was viable in both drinks because its counting plates was higher than 10(6) CFU/mL until day 21st. Between the 7th and 14th day, the rate of growth was higher in the drink that included oat flour, however, at the day 21st the colony density was similar in both drinks.