Search results for "absorptio"
showing 10 items of 2815 documents
Some observations on the determination of total heavy metals in sewage sludge by atomic absorption spectrophotometry after a pressurized acid digesti…
1990
Abstract An economical and simple method for the flame atomic absorption spectrometric determination of Cd, Pb, Ni, Cu, Fe, and Zn in sewage sludges is described. Samples are treated with concentrated HNO 3 in a thermal oven using Pyrex glass tubes hermetically sealed with Bakelite screw caps. The effect of the digestion parameters, such as digestion time, acid volume, sample mass, and temperature, were studied. The precision and accuracy of this procedure were evaluated by the analysis of two BCR (Community Bureau of Reference, European Communities) certified sewage sludge samples (CRM 146 and 144).
Flame atomic absorption analysis of gold in jewelry samples
1990
A new procedure is proposed for the determination of gold by flame atomic absorption in jewelry samples. The method is based on the acid digestion of 10 mg of sample in a microwave oven and on the on-line dilution, using a three-way valve. The dynamic range of the technique is extended to 100 mg/l gold solutions and using a weighted bracketing method for the treatment of the results, accuracy errors lower than 2% can be found in the analysis of real samples as compared with those obtained by fire assay. The method is very fast and implies only little damage to the jewelry samples.
Estimation of Arsenic Bioaccessibility in Edible Seaweed by an in Vitro Digestion Method
2003
The aim of this study was to examine the bioaccessibility (maximum soluble concentration in gastrointestinal medium) of total (AsT) and inorganic (AsI) arsenic contents and the effect on them of cooking edible seaweed, a food of great interest because of its high As content. An in vitro gastrointestinal digestion (pepsin, pH 2, and pancreatin−bile extract, pH 7) was applied to obtain the mineral soluble fraction of three seaweeds (Hizikia fusiforme, Porphyra sp., and Enteromorpha sp.). AsT was determined by dry-ashing flow injection hydride generation atomic absorption spectrometry. AsI was determined by acid digestion, solvent extraction, and flow injection hydride generation atomic absorp…
Adenosine monophosphate-capped gold(i) nanoclusters: synthesis and lanthanide ion-induced enhancement of their luminescence
2016
Reduction of Au3+ in the presence of just adenosine 5′-monophosphate (AMP) and a zwitterionic organic chemical buffering agent, specifically 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), combined with light exposure, gives rise to luminescent, water-soluble Au+ nanoclusters (Au+ NCs). The photoluminescence of these NCs is considerably enhanced by adding Y3+ or the chemically similar Yb3+ lanthanide that leads to Au+/Y3+ and Au+/Yb3+ NCs, respectively. These NCs are characterised by absorption (steady-state), photoluminescence (steady-state and time-resolved), and X-ray photoelectron spectroscopy.
Abdominal fat quantity and distribution in women with polycystic ovary syndrome and extent of its relation to insulin resistance.
2007
Composizione corporea in relazione alla sindrome dell'ovaio policistico. Increased abdominal fat has been linked to insulin resistance and increased cardiovascular risk. Because many patients with polycystic ovary syndrome (PCOS) present abdominal obesity, it may be the cause of insulin resistance in this disorder.Setting: Fat quantity and distribution were evaluated by dual x-ray absorptiometry at the Departments of Clinical Medicine at the University of Palermo and the University of Naples, Italy.Patients: A total of 110 patients with PCOS and 112 weight-matched controls were studied. Anthropometric data, blood glucose, serum insulin, and testosterone were evaluated. Total, trunk, and cen…
Prolonged breast-feeding protects mothers from later-life obesity and related cardio-metabolic disorders
2011
AbstractObjectiveTo investigate the long-term effects of duration of postpartum lactation on maternal body composition and risk for cardio-metabolic disorders in later life.DesignRetrospective study. Body composition was measured using dual-energy X-ray absorptiometry and serum glucose, insulin and lipids were analysed using enzymatic photometric methods 16–20 years after the last pregnancy. Medical history and lifestyle factors were collected via a self-administered questionnaire. Detailed information regarding weight change patterns during each pregnancy was obtained from personal maternity tracking records.SettingCity of Jyväskylä and surroundings in Central Finland.SubjectsTwo hundred a…
Enhancing effect of alpha-hydroxyacids on "in vitro" permeation across the human skin of compounds with different lipophilicity.
2005
The percutaneous penetration-enhancing effects of glycolic acid, lactic acid and sodium lauryl sulphate through the human epidermis was investigated using 5-fluorouracil as a hydrophilic model permeant and three compounds belonging to the phenylalcohols: 2-phenyl-ethanol, 4-phenyl-butanol and 5-phenyl-pentanol. The lipophilicity values of the compounds ranged from log Poct -0.95 to 2.89. The effect of the enhancer concentration was also studied. Skin pretreatment with aqueous solutions of the three enhancers did not increase the permeability coefficient of the most lipophilic compound (log Poct = 2.89). For the other compounds assayed, the increase in the permeability coefficients depended …
Skin-PAMPA: a new method for fast prediction of skin penetration.
2011
The goal of this study was to develop a quick, reliable, and cost-effective permeability model for predicting transdermal penetration of compounds. The Parallel Artificial Membrane Permeability Assay (PAMPA) was chosen for this purpose, as it already has been successfully used for estimating passive gastrointestinal absorption and blood-brain barrier permeability. To match the permeability of the rate-limiting barrier in human skin, synthetic certramides, which are analogs of the ceramides present in the stratum corneum, were selected for the skin-PAMPA model. The final skin-PAMPA membrane lipid mixture (certramide, free fatty acid, and cholesterol) was selected and optimized based on data …
Inhibition of skin inflammation by baicalin ultradeformable vesicles.
2016
The topical efficacy of baicalin, a natural flavonoid isolated from Scutellaria baicalensis Georgi, which has several beneficial properties, such as antioxidative, antiviral, anti-inflammatory and antiproliferative, is hindered by its poor aqueous solubility and low skin permeability. Therefore, its incorporation into appropriate phospholipid vesicles could be a useful tool to improve its local activity. To this purpose, baicalin at increasing concentrations up to saturation, was incorporated in ultradeformable vesicles, which were small in size (∼67nm), monodispersed (PI<0.19) and biocompatible, regardless of the concentration of baicalin, as confirmed by in vitro studies using fibroblasts…
Effect of loperamide on jejunal electrolyte and water transport, prostaglandin E 2-induced secretion and intestinal transit time in man
1991
Jejunal perfusion was performed in 12 healthy volunteers to evaluate the dose dependent effects of loperamide on intestinal absorption, stimulated secretion and transit. In 6 volunteers intestinal perfusion of the jejunal segment with isotonic NaCl solution was followed by addition of loperamide in increasing doses (2–8 mg·l−1). The volunteers were pretreated with 1 mg·l−1 prostaglandin E2 (PgE2) in the perfusate before addition of 4 mg·l−1 loperamide. Phenolsulphonphtalein (PSP) boluses (2 ml) were given to measure mean transit time (MTT). Loperamide 2 mg·l−1 converted the minor secretion after perfusion with the standard solution (water −1.45 ml·min−1, Na −0.09 and Cl −0.04 mmol·min−1) to…