Search results for "acetate"
showing 10 items of 756 documents
Influence of PVP/VA copolymer composition on drug–polymer solubility
2015
In this study, the influence of copolymer composition on drug-polymer solubility was investigated. The solubility of the model drug celecoxib (CCX) in various polyvinylpyrrolidone/vinyl acetate (PVP/VA) copolymer compositions (70/30, 60/40, 50/50 and 30/70 w/w) and the pure homopolymers polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA) was predicted at 25 °C using a thermal analysis method based on the recrystallization of a supersaturated amorphous dispersion (recrystallization method). These solubilities were compared with a prediction based on the solubility of CCX in the liquid monomeric precursors of PVP/VA, N-vinylpyrrolidone (NVP) and vinyl acetate (VA), using the Flory-Huggins …
Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
2019
Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…
Biofiltration of toluene in the absence and the presence of ethyl acetate under continuous and intermittent loading
2008
BACKGROUND: Two peat biofilters were used for the removal of toluene from air for one year. One biofilter was fed with pure toluene and the other received 1:1 (by weight) ethyl acetate:toluene mixture. RESULTS: The biofilters were operated under continuous loading: the toluene inlet load (IL) at which 80% removal occurred was 116 g m−3 h−1 at 57 s gas residence time. Maximum elimination capacity of 360 g m−3 h−1 was obtained at an IL of 745 g m−3 h−1. The elimination of toluene was inhibited by the presence of ethyl acetate. Intermittent loading, with pollutants supplied for 16 h/day, 5 days/week, did not significantly affect the removal efficiency (RE). Biomass was fully activated in 2 h a…
Determination of acetazolamide in human urine samples by reversed-phase high-performance liquid chromatography in the presence of xanthines.
1992
A simple, rapid and selective high-performance liquid chromatographic assay for the determination of acetazolamide in urine samples is described. After extraction with ethyl acetate, the drug is chromatographed on an HP-Hypersil ODS-C18 column with a mobile phase of acetonitrile-phosphate buffer (pH 3) and ultraviolet detection at 275 nm. The efficiency of the extraction, the linearity and the reproducibility of the method permit the evaluation of acetazolamide urinary excretion a long time after its administration.
Lead acetate precursor based p-i-n perovskite solar cells with enhanced reproducibility and low hysteresis
2015
A low temperature approach for the fabrication of p-i-n perovskite solar cells is presented. Using lead acetate-based precursors, flat and homogeneous CH3NH3PbI3 films, compatible with the use of thin organic charge transport layers, can be obtained. The corresponding solar cells showed power conversion efficiency up to 12.5%, with remarkable reproducibility and very low hysteresis.
Determination of liposoluble vitamins in cooked meals, milk and milk products by liquid chromatography
2002
A method for the simultaneous determination of liposoluble vitamins in cooked meals was established. Saponification was performed with 50% (w/v) KOH at 80 degrees C, and ascorbic acid was added as antioxidant. The subsequent extraction was carried out with diethyl ether. This was followed by a liquid chromatographic separation on a reversed-phase C18 column with methanol-water (94:6, v/v as the mobile phase. Retinyl acetate was used as the internal standard. The analytical parameters linearity, detection limit (0.19 and 8.33 microg/100 g for retinol and alpha-tocopherol, respectively), precision of the method (RSD=5.24 and 6.99% for retinol and alpha-tocopherol, respectively) and recovery a…
Characterization of an Italian biotype of clary sage (Salvia sclarea L.) grown in a semi-arid Mediterranean environment
2002
An Italian spontaneous biotype of clary sage (Salvia sclarea L.) was evaluated for its suitability to be cultivated in a semi-arid area and for the influence of these growth conditions on the essential oil composition. Seeds gathered from a spontaneous biotype were sown directly in the field, using a seeding density calculated to achieve a plant population of 7 plants/m2. Essential oils from the inflorescences and leaves of plants harvested at full flowering and early seed ripeness stages were obtained by steam distillation and characterized by GC and GC–MS. The plants showed a good tolerance to the semi-arid growth conditions, yielding more than 700 flowers/plant and about 21 g seeds/plant…
Release of isoamyl acetate from starch pastes of various structures : thermodynamic and kinetic parameters
2004
The release of isoamyl acetate from starch-based matrices was studied on the basis of a cumulative dynamic headspace analysis. Two corn starches were compared, which are known to yield pastes and gels differing in their structures and properties. These properties were assessed by viscometry and viscoelastic measurements. Aroma release was discussed as a function of the structure and texture parameters of the matrix. The release curves obtained from water and from the various starch-based matrices at 25 degrees C showed similar patterns but differed in their initial slopes and in the final plateau values. The lowest initial slopes were obtained for the normal starch dispersions that formed g…
Chemical composition of the essential oils of three endemic species of Anthemis sect. Hiorthia (DC.) R.Fern. growing wild in Sicily and chemotaxonomi…
2014
The chemical composition of the essential oils isolated from the aerial parts of Anthemis pignattiorum Guarino, Raimondo & Domina and A. ismelia Lojac. and the aerial parts and flowers of Anthemis cupaniana Tod. ex Nyman , three endemic Sicilian species belonging to the section Hiorthia, was determined by GC-FID and GC/MS analyses. (Z)-Muurola-4(14),5-diene (27.3%) was recognized as the main constituent of the A. pignattiorum essential oil, together with isospathulenol (10.6%), sabinene (7.7%), and artemisyl acetate (6.8%), while in the oil obtained from the aerial parts of A. ismelia , geranyl propionate (8.8%), bornyl acetate (7.9%), β-thujone (7.8%), neryl propionate (6.5%), and t-muurol…
Il management dell’ipersensibilità dentinale: dalla ricerca alla clinica
2014
Obiettivi. Scopo di questo lavoro è presentare le più recenti acquisizioni in tema di epidemiologia, diagnosi, eziopatogenesi e management clinico dell’ipersensibilità dentinale. Vengono inoltre descritti i prodotti disponibili per il suo trattamento e gli studi sperimentali e clinici condotti per valutarne l’efficacia. Materiali e metodi. Attraverso la banca dati Medline/Pubmed sono stati selezionati i lavori originali, le revisioni della letteratura e le linee guida pubblicate in lingua inglese e in italiano sull’argomento dal 2009 al 2013. Altre fonti sono state selezionate dai riferimenti bibliografici individuati. Risultati e conclusioni. Il management dell’ipersensibilità prevede il c…