Search results for "layer"
showing 10 items of 2667 documents
Retention-activity relationship studies of benzodiazepines by micellar liquid chromatography
1999
Solute partitioning into lipid bilayers of biological membranes is the basis for drug and metabolite uptake, passive transport across membranes and bioaccumulation. In order to emulate in vitro the partitioning process in the biomembranes, different approaches have been proposed. The use of micellar solutions as mobile phases in reversed-phase liquid chromatography (micellar liquid chromatography, MLC) has proven to be valid in the prediction of the biological activities of local anesthetics, catecholamines and barbiturates. In this paper we focus our attention on benzodiazepines. The retention of benzodiazepines using different concentrations of Brij35 as micellar mobile phase in modified …
Designing fluorous domains. Synthesis of a series of pyridinium salts bearing a perfluoroalkylated azole moiety
2006
The synthesis of a series of N-methylpyridinium salts bearing a perfluoroalkylated 1,2,4-oxadiazole or 1,2,4-triazole moiety is reported. X-Ray structures of representative perfluoroalkyl-triazolylpyridine (15) and methyl- pyridinium iodide salt (5a) are reported. Their crystal packing clearly shows segregation between the aromatic and parallel double layer fluorinated regions.
Isolation and identification of the antibacterial compounds from Helichrysum stoechas.
1991
Fractionation of the dicholoromethane extract of the aerial parts of Helichrysum stoechas yielded seven isolates (1-7), which exhibited varying antimicrobial activity against Gram-positive bacteria. Pure compounds 1-3 have been previously reported in the same species and 4 and 5 were identified as italipyrone and plicatipyrone, previously isolated from H. italicum and H. plicatum. The two other isolates are helipyrone (6) and homoarenol (7) mixed with related substances. Compound 6c (4,4'-dihydroxy-5,6,5',6'-tetramethyl-3,3'-methylen-di-pyr-2-one) and 6b helipyrone with one methyl substitution, have not been previously reported in other species.
Experiments on the metyrapone reducing microsomal enzyme system.
1970
The formation of reduced metyrapone [2-methyl-1.2-bis-(3-pyridyl)-1-propanol] from metyrapone [2-methyl-1.2-bis-(3-pyridyl)-1-propanone] in the liver has been studied. Reduced metyrapone appeared as the main metabolite of metyrapone in the isolated perfused rat liver. Experiments on the intracellular distribution of the metyrapone reducing activity revealed that metyrapone reductase is mainly localized in the microsomal fraction. In the 105,000 × g supernatant only a little activity was found.
Quinol sulphate, a new conjugate of phenol in goldfish.
1983
1. Metabolism of phenol in goldfish yielded the known phenyl conjugates in fish--phenyl sulphate and phenyl glucuronide. Additionally, quinol sulphate, a new conjugate of phenol in fish, was detected.
Molecular Fingerprints of Thyroid Cancer Cells by Using Library of Molecular Receptors Formed by N-Lipidated Peptides Immobilized on Cellulose
2018
This paper presents a novel diagnostic method using a library of molecular receptors to assess the composition of healthy and tumorous tissue samples. Molecular receptors were formed by self-organization of N-lipidated peptides attached in the regular fashion via aminophenylamino-1,3,5-triazine linkers to the surface of a cellulose plate. The library was cloned into multiple, identical copies. A new clone was used in each test. The binding process was monitored by staining the discs with Brilliant Black and quantitative color measure- ment was performed in 256-grade grayscale. Substantial differences in the composition of healthy and tumor samples were observed in most cases. The sharp diff…
Hydrolytic action of phospholipase A2 in monolayers in the phase transition region: direct observation of enzyme domain formation using fluorescence …
1990
Phospholipase A2, a ubiquitous lipolytic enzyme highly active in the hydrolysis of organized phospholipid substrates, has been characterized optically in its action against a variety of phospholipid monolayers using fluorescence microscopy. By labeling the enzyme with a fluorescent marker and introducing it into the subphase of a Langmuir film balance, the hydrolysis of lipid monolayers in their liquid-solid phase transition region could be directly observed with the assistance of an epifluorescence microscope. Visual observation of hydrolysis of different phospholipid monolayers in the phase transition region in real-time could differentiate various mechanisms of hydrolytic action against …
Structure features and phase behaviour of amphiphilic N-tetradecyl-β-hydroxy-propionic acid amide monolayers
1997
Abstract Two phase transitions of N-tetradecyl-β-hydroxy-propionic acid amide monolayers at the air/water interface were studied by means of pressure/surface area ( π A ) isotherms, Brewster angle microscopy (BAM) and synchrotron X-ray grazing-incidence diffraction (GID). At T≤15 °C the π A isotherms show two plateau regions indicating two first-order phase transitions. In the first main transition from the lowdensity fluid-like phase to a condensed phase, dendritic growth of condensed phase domains with six main growth directions was observed by BAM. A second transition from a condensed phase with large tilt angle to a condensed phase with smaller tilt angle and a denser arrangement of mol…
Effect of electron correlation corrections on phase competition in Ag film on MgO substrate
2002
Abstract The effect of electron correlation corrections in the novel theory predicting the growth mode of a thin metallic film on an insulating substrate has been studied. We discuss the influence of the substrate slab thickness on the energies of formation for several two-dimensional phases, which, in principle, may form in Ag layer on (0 0 1) MgO substrate. We analyze also the sensitivity of the key energy parameter––Fourier transform of the mixing potential V (0) to the choice of correlation functionals.