Search results for "Styrene"
showing 10 items of 561 documents
Estimation of the size of liposomes by modified HDC
1991
Internal calibration in modified hydrodynamic chromatography has been realized by the approach of Prieve and Hoysan, i.e. the use of polystyrene monodisperse latexes to evaluate the equivalent capillary radius, R. The value obtained has been used to estimate the average sizes of a variety of liposome samples from egg yolk lecithin.
Stationary–mobile phase distribution coefficient for polystyrene standards
2002
The measured shifts of the retention volume V R of polystyrene (PS) towards lower values in benzene–methanol (Bz–MeOH), and towards higher values in butanone–heptane (But–Hep) are in agreement with our theoretical model, in which both MeOH and But are adsorbed on Lichrospher. This paved way for us to model the chromatographic stationary (s)-phase as MeOH and the mobile (m)-phase as Bz–MeOH, and to calculate the distribution coefficients for PS. For But–Hep, the s-phase has been modeled as But, and the m-phase as But–Hep. A linear relation for the experimental equilibrium distribution P sm of PS is shown between the s- and m- phases in Bz–MeOH and But–Hep vs. the logarithm of the molecular m…
Untersuchungen zu den orientierungs- und dichtefluktuationen in amorphen polymeren mit hilfe der lichtstreuung
1976
Es wurden mit einem Lichtstreuphotometer die Orientierungs- und Dichtefluktuationen in den amorphen Polymeren «Polycarbonat» (Poly(oxycarbonyloxy-1,4-phenylenisopropyliden-1,4-phenylen)) und Polystyrol in Abhangigkeit von der Temperatur untersucht. Ferner fuhrten wir erganzende Messungen an Oligomeren des Polystyrols und an der flussig-kristallinen Verbindung 4-Butyl-N-(p-methoxybenzyliden)anilin (MBBA) in der isotropen Phase durch. Aus der Hohe der depolarisierten Lichtstreuung ergab sich, das eine Orientierungskorrelation, wie sie fur einige Bundelmodelle vorgeschlagen wurde, nicht auftritt. Besonders detaillierte Aussagen konnten fur Polystyrol gemacht werden. Die depolarisierte Lichtstr…
Production de styrene par Penicillium camemberti Thom
1989
National audience; The Celluloïd taste observed in some mould-ripened cheeses is bound to the presence of styrene in these cheeses. The accumulation of this molecule was only detected on cultures of some strains of Penicillium camemberti. It seems to be bound to a deregulation of oxidative metabolism of tneee strains.; L'apparition du goût de Celluloïd dans les fromages à pâte molle à croûte fleurie est liée à la présence de styrène dans ces fromages. L'accumulation de cette molécule n'est observée que sur des cultures de souches particulières de Penicillium camemberti. Elle semble liée à un dérèglement du métabolisme oxydatif de ces souches.
How Low Can You Go? Low Densities of Poly(ethylene glycol) Surfactants Attract Stealth Proteins.
2018
It is now well-established that the surface chemistry and “stealth” surface functionalities such as poly(ethylene glycol) (PEG) chains of nanocarriers play an important role to decrease unspecific protein adsorption of opsonizing proteins, to increase the enrichment of specific stealth proteins, and to prolong the circulation times of the nanocarriers. At the same time, PEG chains are used to provide colloidal stability for the nanoparticles. However, it is not clear how the chain length and density influence the unspecific and specific protein adsorption keeping at the same time the stability of the nanoparticles in a biological environment. Therefore, this study aims at characterizing the…
Disulfide-crosslinked hyaluronan-gelatin hydrogel films: a covalent mimic of the extracellular matrix for in vitro cell growth
2003
A new disulfide crosslinking method was developed for the preparation of blended hyaluronan (HA)-gelatin hydrogels to form a synthetic, covalently linked mimic of the extracellular matrix (ECM). The HA and gelatin were chemically modified using 3,3′-dithiobis(propionic hydrazide) (DTP). After reduction with dithiothreitol (DTT), the thiol derivatives of HA (HA-DTPH) and gelatin (gelatin-DTPH) were obtained and characterized. To minimize interference with biological function, the degree of substitution of HA-DTPH and gelatin-DTPH was kept below 50%. Solutions of HA-DTPH and gelatin-DTPH in varying blends (20%, 40%, 60%, 80% gelatin) were prepared in 1% w/v NaCl and crosslinked by disulfide b…
Induction of rat liver microsomal epoxide hydrolase by its endogenous substrate 16α, 17α-epoxyestra-1,3,5-trien-3-ol
1995
1. The influence of the endogenous steroid epoxides 16 alpha, 17 alpha-epoxyestra-1,3,5(10)-trien-3-ol (estroxide) and 16 alpha, 17 alpha-expoxiandrost-4-en-3-one (androstene oxide) and their metabolic precursors estra-1,3,5(10), 16-tetraen-3-ol (estratetraenol) and androsta-4, 16-dien-3-one (androstadienone) on the specific activities of hepatic microsomal and soluble epoxide hydrolase, glutathione S-transferase, dihydrodiol dehydrogenase, and 7-ethoxycoumarin deethylase was investigated in the male Sprague-Dawley rat. 2. Both estroxide and estratetraenol induced microsomal epoxide hydrolase activity towards styrene oxide and estroxide itself 2-2.5-fold and glutathione conjugation of 1-chl…
Effect of dietary antioxidants on benzo[a]pyrene metabolism in rat liver microsomes
1983
Feeding of rats with 1% ethoxyquin (EQ) and butylated hydroxytoluene (BHT) but not butylated hydroxyanisole (BHA) increases the formation rate of benzo[a]pyrene (BP)-4,5-dihydrodiol from BP in hepatic microsomes. The production of other BP-dihydrodiols and of BP phenols is decreased after treatment with EQ, BHT and BHA. EQ and BHT are more effective than BHA in inducing epoxide hydrolase (EH) activity towards styrene oxide as the substrate.
Purification and characterization of rat-liver cytosolic epoxide hydrolase.
1988
Rat liver cytosolic epoxide hydrolase has been purified and characterized. The enzyme was purified from tiadenol-induced rat liver 540-fold with respect to trans-stilbene oxide as a substrate. Similar purification was obtained with the substrates trans-beta-ethyl styrene oxide and styrene 7,8-oxide, the specific activities decreasing in the order trans-beta-ethyl styrene oxide greater than styrene 7,8-oxide greater than trans-stilbene oxide. The enzyme exerts highest activity at pH 7.4 Km and Vmax of the pure enzyme for trans-stilbene oxide were 1.7 microM and 205 nmol x min-1 x mg protein-1 respectively. With trans-stilbene oxide as a substrate, the inhibition by organic solvents (2.5% by …
Endogenous role of epoxide-hydratase. Development of a steroid epoxide-hydratase assay and properties of the enzyme.
1979
A highly sensitive and rapid radiometric assay for the determination of specific epoxide hydratase activity with a steroid epoxide (16α, 17α-epoxy-1,3,5(10)-estratrien-3-ol, ‘estroxide’) has been developed. The unreacted substrate was separated from the product 1,3,5(10)-estratrien-3,16β,17α-triol by extraction into light petroleum. The product was then extracted into ethyl acetate and measured by scintillation spectrometry. Radiochromatography established that after subtraction of the blank the entire radioactivity measured in the ethyl acetate phase resulted from the product 1,3,5(10)-estratrien-3,16,17-triol, whilst high performance liquid chromatography with the four possible isomers of…