Search results for "Tetra"

An investigation of the stability of free and glucuronidated 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid in authentic urine samples.

2004

Preanalytical stability of a drug and its major metabolites is an important consideration in pharmacokinetic studies or whenever the analyte pattern is used to estimate drug habits. Firstly, the stability of free and glucuronidated 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH, THCCOOglu) in authentic urine samples was investigated. Random urine samples of cannabis users (n = 38) were stored at -20, 4, and 20 degrees C up to 15 days and up to 5 days at 40 degrees C, and alterations of the analyte pattern during storage were followed by liquid chromatography-tandem mass spectrometry. Secondly, the influence of pH (range 5.0-8.0) on the stability of the analytes was studied us…

Evidence of tetraphenylporphyrin monoacids by ion-transfer voltammetry at polarized liquid|liquid interfaces

2008

We present a simple methodology to illustrate the existence of tetraphenylporphyrin monoacid based on ion-transfer voltammetry at a polarized water|1,2-dichloroethane interface and organic pK values are also estimated.

First signals of electrochemically oxidized species of TTF and TMT-TTF : a study by in situ spectroelectrochemical FTIR and DFT calculations

2003

A first study by in situ FTIR spectroelectrochemistry of TTF and TTM-TTF has been undertaken. The oxidation, in this case, is caused only by electrochemistry, which constitutes a clear advantage over chemical oxidation since no side products are present in the solution. In this context, we obtained the signals of neutral, radical cation, and dication species of TTF and TTM-TTF. The experimental conditions were chosen in order to avoid the possible formation of π-dimer species and to obtain a satisfactory signal-to-noise ratio. A weak signal was detected for TTF and a stronger one for TTM-TTF. The changes induced by the oxidation process in the IR spectra of TTF and TTM-TTF have been analyze…

Optical saturation thermal lens spectrometry in non-polar solvents

1997

Abstract A model for thermal lens spectrometry (TLS) in partial optical saturation conditions which was previously applied to polar solutes in aqueous media is now checked with non-polar organic dyes and metal dithizonates in carbon tetrachloride. Some literature data are also examined. Most data can be consistently explained on the basis of the molecular structures, the sensitivity increasing with the capability of the solute to rapidly communicate the absorbed energy to the solvent molecules.

Anatase nanoparticles boundaries resulting from titanium tetrachloride hydrolysis

2017

An important factor that governs solar energy transformation into electrical or chemical energy, when using nanoparticles-based devices, is the spatial location of traps limiting electron transport. Evidences have been presented indicating that the electron diffusion is strongly influenced by nanoparticle boundaries, whose characteristics depend on the particles preparation. In the present work we have studied the role of hydrated excess proton structures in the formation of anatase nanoparticles boundaries in samples prepared by TiCl4 hydrolysis at low temperature and strong acidic conditions. The samples, constituted by anatase nanocrystals but, mainly, by amorphous titania, are studied b…

Angiotensin Receptor Neprilysin Inhibition Compared With Enalapril on the Risk of Clinical Progression in Surviving Patients With Heart Failure

2015

Background— Clinical trials in heart failure have focused on the improvement in symptoms or decreases in the risk of death and other cardiovascular events. Little is known about the effect of drugs on the risk of clinical deterioration in surviving patients. Methods and Results— We compared the angiotensin-neprilysin inhibitor LCZ696 (400 mg daily) with the angiotensin-converting enzyme inhibitor enalapril (20 mg daily) in 8399 patients with heart failure and reduced ejection fraction in a double-blind trial. The analyses focused on prespecified measures of nonfatal clinical deterioration. In comparison with the enalapril group, fewer LCZ696-treated patients required intensification of med…

Inhibitory effects of N-acetylcysteine on superoxide anion generation in human polymorphonuclear leukocytes.

1997

Abstract It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3–300 nm) and phorbol myristate acetate (160 pm–160 nm) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcystein…

"Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y = Br, Cl; bdmim = 1-butyl-2,3-dim…

2013

Abstract The discrete mixed [TeBrxCl6−x]2− anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X = Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X = Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4]2− and [TeBr4Cl2]2…

Synthesis and conformational analysis of tetrahydroisoquinoline- and piperidine-fused 1,3,4,2-oxadiazaphosphinanes, new ring systems

2006

Abstract Through cyclization of tetrahydroisoquinoline and piperidine 1,2-hydrazino alcohols with phenylphosphonic dichloride and phenyl dichlorophosphate, P-epimeric diastereomers of 1,6,7,11b-tetrahydro-4H-1,3,4,2-oxadiazaphosphino[5,4-a]isoquinoline-3-oxides ( 13 and 14 ), 1,6,11,11a-tetrahydro-4H-1,3,4,2-oxadiazaphosphino[4,5-b]isoquinoline-3-oxides ( 15 and 16 ) and 1,6,7,8,9,9a-hexahydro-4H-pyrido[1,2-d][1,3,4,2]oxadiazaphosphinane-3-oxides ( 17 and 18 ), the first representatives of these ring systems, were prepared. NMR and X-ray diffraction studies revealed that, independently of the P-substituent and the relative configuration of the phosphorus atom, 13 , 14 , 17 and 18 could be c…

Metabolites from Mediterranean plants: characterization and transformation. Chemotaxonomic assessment and biological activity.

Questo progetto di ricerca ha lo scopo di ampliare le conoscenze di alcune piante appartenenti alla flora Mediterranea. Le piante da studiare sono state scelte in seguito ad un’attenta analisi bibliografica tra specie poco sudiate. La scelta è quindi ricaduta su nove specie appartenenti al genere Anthemis, due specie appartenenti al genere Pulicaria e sulle specie di Tetraclinis articulata, Salvia argentea, Ajuga tenorei, Ballota hispanica, Moluccella Spinosa e Thapsia garganica. Di esse sono stati preparati ed identificati i componenti degli oli essenziali e successivamente effettuati su di essi i saggi antibatterici. Dagli estratti delle specie di Tetraclinis articulata e Ajuga tenorei so…