Light scattering study of salt-free "polyelectrolyte behaviour" of monotelechelic ionomers in a polar solvent

in Polymer (1996), 37(16), 3741-3744

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e ... [more ▼]

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e., negative angular dependence of the reciprocal scattering in static light scattering and an appearance of the fast mode in dynamic light scattering) has been observed for monotelechelic ionomer solutions in a polar solvent. This indicates that only single charge (per chain) is sufficient to produce intermolecular electrostatic interactions, which are responsible for such characteristic behaviour. However, the 'characteristic' behaviour, which is typically observed at higher concentrations for polyelectrolyte and random ionomer solutions (i.e., large positive apparent radius of gyration in static scattering and appearance of the slow mode in addition to the fast mode in dynamic scattering) has not been observed to date for monotelechelic ionomer solutions. The absence of high-concentration characteristics for the monotelechelic ionomer solutions gives additional insight as to the nature and structure of 'heterogeneities' in salt-free polyelectrolyte solutions, which is still controversial. [less ▲]

A Global Understanding of Transient Surface Flows Applied to Hydrology and River Processes

in XI International Conference on Computational Methods in Water Resources (1996, July 22)

Research programme on the European otter in the Trebon biosphere reserve (Czech Republic)

Report (1996)

A Strategy for Multiple Immunophenotyping by Image Cytometry: Model Studies Using Latex Microbeads Labeled with Seven Streptavidin-Bound Fluorochromes

in Cytometry (1996), 24(3), 214-25

Multiple immunophenotyping is aimed at identifying several cell populations in a single labeling procedure by their ability to bind combinations of specific labeled antibodies. The present work ... [more ▼]

Multiple immunophenotyping is aimed at identifying several cell populations in a single labeling procedure by their ability to bind combinations of specific labeled antibodies. The present work demonstrates the simultaneous discrimination by using image cytometry of aminomethylcoumarin acetate (AMCA), Lucifer yellow (LY), fluorescein isothiocyanate (FITC), R-phycoerythrin (PE), PE-Texas red tandem (Red613), peridinin-chlorophyll protein (PerCP), and allophycocyanin (APC), which were all bound to latex beads as streptavidin-conjugated fluorochromes. This has been the result of a step-by-step optimization of the several factors affecting the sensitivity and specificity of multiple immunofluorescence analysis. First, 14 streptavidin-conjugated fluorochromes were evaluated by using spectrofluorometry. A primary selection was then made of ten spectrally separable dyes that could be evaluated by using image cytometry. These dyes were bound to latex particles, and specific filter combinations were assembled to minimize crosstalk between fluorophores while preserving sufficient fluorescence intensity and counting statistics. Potential probe associations were then assessed by measuring the emissions of all fluorochromes that were detected by each filter combination. The resulting crosstalk matrix served as the basic tool both for final selection of the optimal filter combination and for dye set (composed, in this case, of the seven fluorochromes described above) and for mathematical correction of residual spectral overlap. Next, an image cytometry system was adapted to collect seven images of matched brightness with the selected combination of excitation/emission filters and dichroic mirrors. Finally, seven-parameter synthetic images were generated by digital image processing. [less ▲]

Intracellular distribution of the ORF4 gene product of varicella-zoster virus is influenced by the IE62 protein

in Journal of General Virology (1996), 77(Part 7), 1505-1513

Varicella-zoster virus (VZV) open reading frame 4-encoded protein (IE4) possesses transactivating properties for VZV genes as well as for genes of heterologous viruses, The major regulatory immediate ... [more ▼]

Varicella-zoster virus (VZV) open reading frame 4-encoded protein (IE4) possesses transactivating properties for VZV genes as well as for genes of heterologous viruses, The major regulatory immediate-early protein of VZV (IE62) is a transactivator of VZV gene expression, In transfection assays, IE4 has been shown to enhance activation induced by IE62, To investigate the functional interactions underlying this observation, indirect immunofluorescence studies were undertaken to determine whether IE62 could influence IE4 intracellular localization in transfected cells, In single transfections, IE4 was predominantly found in cytoplasm, In cotransfection with IE62, the IE4 localization pattern was altered, with nuclear staining predominating over cytoplasmic staining, This effect was specific to the IE62 protein since the gene products of ORF63 and ORF61, which are also regulatory proteins, did not influence IE4 distribution, The use of IE62 mutants indicated that IE62 influence is independent of its transactivation function and that the integrity of regions 3 and 4 is required, IE62 remained nuclear whether IE4 was present or not, These observations underline differences in the regulation of gene expression between VZV proteins and their herpes simplex virus type 1 homologues, In infected cells, IE4 was only sometimes found to colocalize with IE62 in nuclei, This observation suggests that when all VZV proteins are present, complex interactions probably occur which could diminish the influence of IE62. [less ▲]

A full heteroscedastic one-way error components model for incomplete panel: pseudo-maximum likelihood estimation and pseudo Lagrange multiplier testing

Conference (1996, June 27)

Constructive Lyapunov stabilization of nonlinear cascade systems

in IEEE Transactions on Automatic Control (1996), 41(12), 1723-1735

High-temperature polyimide nanofoams for microelectronic applications

in Reactive & Functional Polymers (1996), 30(1-3), 43-53

Foamed polyimides have been developed in order to obtain thin film dielectric layers with very low dielectric constants for use in microelectronic devices. In these systems the pore sizes are in the ... [more ▼]

Foamed polyimides have been developed in order to obtain thin film dielectric layers with very low dielectric constants for use in microelectronic devices. In these systems the pore sizes are in the nanometer range, thus, the term 'nanofoam'. The polyimide foams are prepared from block copolymers consisting of thermally stable and thermally labile blocks, the latter being the dispersed phase. Foam formation is effected by thermolysis of the thermally labile block, leaving pores of the size and shape corresponding to the initial copolymer morphology. Nanofoams prepared from a number of polyimides as matrix materials were investigated as well as from a number of thermally labile polymers. The foams were characterized by a variety of experiments including TEM, SAXS, WAXD, DMTA, density measurements. refractive index measurements and dielectric constant measurements. Thin film foams, with high thermal stability and low dielectric constants approaching 2.0, can be prepared using the copolymer/nanofoam approach. [less ▲]

Compositional Specification of ODP Binding Objects

in Information Network and Data Communication (1996, June)

A building blocks approach for the formal specification of binding objects in the ODP Computational Model is presented. The formal notation that is used is based on LOTOS extended with two features - real ... [more ▼]

A building blocks approach for the formal specification of binding objects in the ODP Computational Model is presented. The formal notation that is used is based on LOTOS extended with two features - real time and gate passing. These features are among the extensions that are currently studied in the ISO standardisation Formal Description Techniques group. We apply our building blocks approach to the specification of a multicast, multimedia binding object. [less ▲]

Relationship between auditivo-vocal short-term memory and lexical knowledge in Down'syndrome

Poster (1996, May 10)

Some neuropsychological studies of brain damaged patients presenting memory deficits suggest that working memory directly contribute to the long-term learning of non-familiar phonological structures. It ... [more ▼]

Some neuropsychological studies of brain damaged patients presenting memory deficits suggest that working memory directly contribute to the long-term learning of non-familiar phonological structures. It seems that a phonological store impairment leads to problems in learning new words (Baddeley, Papagno & Vallar, 1988). Gathercole and Baddeley (1993) studies of normal young children lead to the same conclusion. Phonological short-term memory abilities of 4-5 years-old children directly influence lexical acquisition. Children who exhibit the higher phonological memory skills produce higly discriminable and stable phonological memory traces. For these children, there is a greater probability that memory traces become durable and semanticaly linked to the referent. One can then conclude that the phonological short-term memory abilities directly influence the way young children acquired new vocabulary items. A study of memory abilities and lexical knowledge of Down's syndrome subjects (mental age:3;5 to 5;4 years old, chronological age: 8;10 to 25;11 years old) lead us to the following conclusion: in Down's syndrome subjects, as well as in normal subjects, one cannot reject the hypothesis that lexical knowledge are linked to the subjects phonological short-term memory abilities and more specially to non-word repetition. [less ▲]