Search results for "hydrophobic"
showing 10 items of 332 documents
Micellar versus hydro-organic mobile phases for retention-hydrophobicity relationship studies with ionizable diuretics and an anionic surfactant
2004
Abstract Logarithm of retention factors (log k ) of a group of 14 ionizable diuretics were correlated with the molecular (log P o/w ) and apparent (log P app ) octanol–water partition coefficients. The compounds were chromatographed using aqueous–organic (reversed-phase liquid chromatography, RPLC) and micellar–organic mobile phases (micellar liquid chromatography, MLC) with the anionic surfactant sodium dodecyl sulfate (SDS), in the pH range 3–7, and a conventional octadecylsilane column. Acetonitrile was used as the organic modifier in both modes. The quality of the correlations obtained for log P app at varying ionization degree confirms that this correction is required in the aqueou…
The stability and functional properties of proteoliposomes mixed with dextran derivatives bearing hydrophobic anchor groups
1992
Liposomes composed of Escherichia coli phospholipid were coated with polysaccharides bearing hydrophobic palmitoyl anchors. The effect on the stability of liposomes without or with integral membrane proteins was investigated. A high concentration of hydrophobized dextrans protected the liposomes against detergent degradation, decreased the fluidity of the membranes, prevented fusion of the liposomes and enhanced their stability. Proteoliposomes containing beef heart cytochrome-c oxidase and the lactose transport carrier of E. coli were similarly affected by coating with the dextrans. Under these conditions both membrane proteins were still active. Long-term stability of the coated liposomes…
Performance of porous silica layers in open-tubular columns for liquid chromatography
1989
Abstract Progress has been made in the preparation of porous silica layers in fused-silica capillaries for open-tubular liquid chromatography. The porous silica layer is prepared by (i) static coating of the silica precursor, polyethoxysiloxane (PES), followed by (ii) converting the PES film into a porous silica layer with ammonia solution. The porous silica layer can be easily modified by silane reagents commonly used in packed column high-performance liquid chromatography. The performance of the silica layer with the different phase systems was tested with polyaromatic hydrocarbons and derivatized amino acids as samples.
Dissolution of resin acids, retene and wood sterols from contaminated lake sediments.
2005
The dissolution potency of hydrophobic resin acids (RAs), retene and wood sterols from sediments was studied. These wood extractives and their metabolites are sorbed from pulp and paper mill effluents to downstream sediments. With harmful components like these, sediments can pose a hazard to the aquatic environment. Therefore, sediment elutriates with water were produced under variable conditions (agitation rate and efficiency, time), and concentrations of the dissoluted compounds were analyzed. Both naturally contaminated field sediments and artificially spiked sediments were studied. By vigorous agitation RAs can be released fast from the sediment matrix and equilibrium reached within 3 d…
Identification of binding peptides on calcium silicate hydrate: a novel view on cement additives.
2014
Cement is the most used industrial product in the world. Although the chemical composition of the material has stayed more or less the same since its discovery by the Romans around 2000 years ago, [ 1 ] the performance has been increased by chemical additives. Spectacular buildings like the Willis Tower in Chicago, Taipei 101 or lately the over 800 m high Burj Khalifa in Dubai were realizable thanks to the development of high performance building materials. [ 2 ] Not only for such prestige objects but also in daily building processes, the trend goes towards always higher buildings because of the continued urbanization which was identifi ed already in 1982 as one of the so-called “megatrends…
Estimation of the effect of the acidosis and alkalosis on the anesthetic potency of local anesthetics by biopartitioning micellar chromatography and …
2004
Local anesthetics are hydrophobic compounds and weak bases with protonation constants ranged between 7.5 and 8.8. These drugs block reversibly nerve conduction near their site of application or injection and thus produce temporary loss of feeling or sensation in a limited area of the body. The efficacy of anesthetic blockade of local anesthetics depends on the charged/uncharged form ratio and the hydrophobicity of the compounds. In addition their toxicological effects have been reported to be highly dependent on the physiological pH. Biopartitioning micellar chromatography (BMC) and micellar electrokinetic chromatography (MEKC), that use micellar solutions as mobile phases, have proven to b…
Die Bedeutung der Bindung von Pharmaka an Albumin und Erythrocyten eines Perfusionsmediums der isolierten Rattenleber
1971
The binding of lipophilic drugs to albumin and erythrocytes and its importance for the uptake of the drugs into the isolated rat liver were investigated. Promazine and chlorpromazine were taken as lipophilic drugs, which were compared in some experiments with 3,3′-dimethyl-4,4′-diacetyldiphenylbisguanylhydrazone (BG 60), a much more hydrophilic drug.
Effects of electric charges on hydrophobic forces. II.
2000
We study by molecular-dynamics simulations the effect of electric charges of either sign on hydrophobic interactions and on the dynamics of hydration water, using explicit water and very simplified solutes. Results show that the presence of a charged solute can disrupt the "hydrophobic contact bond" between two apolar solutes nearby, by forcing them towards a different configuration. As a consequence of different structural changes of the solvent caused by charges of opposite sign, the effect is markedly charge-sign-dependent. Analogous weaker effects appear to be induced by the presence of one additional apolar element. The dynamics of hydration water around each solute is also seen to be …
Membrane-mediated Protein-protein Interaction: A Monte Carlo Study
2012
We investigate membrane-mediated interactions between transmembrane proteins using coarse-grained models. We compare the effective potential of mean force (PMF) between two proteins, which are always aligned parallel to the z-axis of the simulation box, with those PMFs obtained for proteins with fluctuating orientations. The PMFs are dominated by an oscillatory packing-driven contribution and a smooth attractive hydrophobic mismatch contribution, which vanishes if the hydrophobic length of the protein matches the thickness of the membrane. If protein orientations are allowed to fluctuate, the oscillations are greatly reduced compared to proteins with fixed orientation. Furthermore, the hydr…
Fluid flow simulations meet high-speed video : Computer vision comparison of droplet dynamics
2018
Hypothesis While multiphase flows, particularly droplet dynamics, are ordinary in nature as well as in industrial processes, their mathematical and computational modelling continue to pose challenging research tasks - patent approaches for tackling them are yet to be found. The lack of analytical flow field solutions for non-trivial droplet dynamics hinders validation of computer simulations and, hence, their application in research problems. High-speed videos and computer vision algorithms can provide a viable approach to validate simulations directly against experiments. Experiments Droplets of water (or glycerol-water mixtures) impacting on both hydrophobic and superhydrophobic surfaces …