Search results for "SoMe"
showing 10 items of 5114 documents
Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins
2002
The detailed studies concerning capillary electrophoresis separation of aminophosphonic acid enantiomers with various commercially available cyclodextrins are presented. The obtained results show that the separation of these stereoisomers is dependent on pH of background electrolyte, concentration of cyclodextrin as well as on the type of applied chiral selector. The separation mechanism is based on the co-operative effect of hydrogen bond type interactions enhanced by hydrophobic forces and sterical constrains between aminophosphonate and cyclodextrin. With application of elaborated method, enantiomeric baseline or partial separation of 18 alpha-aminophosphonic acids was achieved. This sep…
Complexes of star-shaped cationic polyelectrolytes with anionic liposomes: Towards multi-liposomal assemblies with controllable stability
2016
Abstract Complexes were formed via the electrostatic interaction between 30–50 nm anionic liposomes and a star-shaped polyelectrolyte, poly{[2-(methacryloyloxy)ethyl]trimethyl ammonium iodide}, having cationic arms that radiate from a silicon-based central core. The complexation was investigated with attention given to assessing the capacity of the cationic stars for the anionic liposomes (both liquid and solid); the integrity of the complexed liposomes; and the stability of the resulting star/liposome complexes in aqueous salt solutions. We have found that by changing the content of anionic groups in the liposomal membrane as well as the phase-state of membrane, the stability of star/lipos…
Dietary arachidonic acid and hepatic desaturation of fatty acids in obese zucker rats
1998
The effect of low levels of dietary arachidonic acid (20:4n-6) on Δ6 desaturation of linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3), and on Δ5 desaturation of dihomo-γ-linolenic acid (20:3n-6) were studied in liver microsomes of obese Zucker rats, in comparison with their lean littermates. Fatty acid composition of serum total lipids and of phospholipids from liver microsomes and from total heart and kidney was determined to see whether modifications of desaturation rate, if any, were reflected in the tissue fatty acid profiles. Animals fed for 12 wk on a balanced diet, containing 20:4n-6 and 18:2n-6, were compared to those fed 18:2n-6 only. The low amount of dietary 20:4n-6 greatly…
PPARgamma agonist pioglitazone does not enhance performance in mice
2013
Peroxisome-proliferator-activated receptor (PPAR) delta and adenosine monophosphate (AMP)-activated protein kinases (AMPKs) regulate the metabolic and contractile characteristics of myofibres. PPAR proteins are nuclear receptors that function as transcription factors and regulate the expression of multiple genes. AMPK has been described as a master metabolic regulator which also controls gene expression through the direct phosphorylation of some nuclear proteins. Since it was discovered that both PPARdelta agonists (GW1516) and AMPK activators (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, known as AICAR) are very effective performance-enhancing substances in sedentary mice, the Worl…
Competition between decarboxylation and isomerization in the C3H5O 2+ energy surface. Justification of the experimental results by molecular orbital …
1994
In constrast with recent molecular orbital calculations on the decarboxylation of O-protonated 2-oxetanone, this experimental work indicates that no decarboxylation of this cation occurs in sulphuric acid solution up to 150°C, but instead a clean isomerization to protonated acrylic acid takes place. Parallel theoretical work shows that the gas-phase model is too crude to account successfully for the experimental facts obtained in acidic media. However, the latter are well reproduced when the effect of the solvent is taken into account. The present findings do not necessarily invalidate the reaction mechanism currently accepted to explain the rate enhancement and change of stereochemistry ac…
On the Mechanism of Xylene Isomerization and its Limitations as Reaction Test for Solid Acid Catalysts
1993
The kinetics of the gas-phase isomerization of m-xylene, over a series of ultraestable Y zeolites, has been studied in a fixed-bed flow reactor under initial conditions. Using deuterated p-xylene as reactant it has been seen that more than 20% of the m- and o-xylene obtained, are formed via a bimolecular mechanism. The relative proportion of uni- to bimolecular mechanism depends on the zeolite composition. The relation between the turnover number, calculated from the kinetic rate constant for the unimolecular mechanism, and the framework Al content of the zeolite, was coincident with the topological zeolite model. Besides, the values of the adsorption constants indicate that dealumination h…
ChemInform Abstract: Differential Reactivity of Fluorinated Homopropargylic Amino Esters vs Gold(I) Salts. The Role of the Nitrogen Protecting Group.
2015
The gold(I)-catalyzed hydroarylation/isomerization reaction of N-protected homopropargyl amino esters (III) gives quinoline derivatives of type (IV).
Complex tauto- and rotamerism of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines
2005
Detailed NMR spectral analysis of CDCl3 solutions of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines reveals three or four tautomeric forms. Apart from 2-[(benzylideneamino)methyl]aniline, the other chain tautomeric forms are present only in minor quantities. In general, electron-donating substituents increase the contribution of all chain forms. Lowering the temperature of the CDCl3 solution of 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines decreases the content of the 2-[(benzylideneamino)methyl]aniline form. At the same time, the amount of the ring form increases. Opening of the tetrahydropyrimidine ring in 2-(R-phenyl)-1,2,3,4-tetrahydroquinazolines was found to be an endothermic process espec…
Significance of Induction Phenomena
1978
A number of foreign compounds induce the proliferation of the hepatic smooth endoplasmatic reticulum and thereby increase the activity of monooxygenases that metabolize drugs and other foreign compound. With reference to the safety of food additives some antioxidants have been examined by various authors for their inducing capacity, in doses well above those ingested with treated food and above the stipulated accepted daily intake (ADI). Thus feeding of rats with the very high dose of 500 mg/kg body weight of butylated hydroxtoluene (BHT) resulted in an increase in its own oxidative metabolism. Also in monkeys BHT produces an inductive increase of microsomal enzyme activity, cytochrome P 45…