Search results for "selenium"
showing 10 items of 178 documents
Organotin(IV) selenate derivatives – Crystal structure of [{(Ph 3 Sn) 2 SeO 4 } ⋅ CH 3 OH] n
2021
Abstract Crystallization of [(Ph3Sn)2SeO4] ⋅ 1.5H2O in methanol leads to the formation of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n (1) which constitutes a new specimen of organotin(IV) selenate derivatives. In the solid state, complex 1 is arranged in polymeric zig-zag chains, composed of alternating Ph3Sn and SeO4 groups. In addition, pendant Ph3Sn ⋅ CH3OH moieties are branched along chains according to a syndiotactic organization and via Sn-O-Se connections. From a supramolecular point of view, intermolecular hydrogen bonds established between the selenate groups (uncoordinated oxygen) and the hydroxyl functions (CH3OH) of the pendant groups link the chains together.
Synthesis, spectroscopic study, and crystal structure of a new organotin(IV) selenate derivative
2018
Abstract The polymeric organotin(IV) selenate complex [(Me3Sn)3(SeO4)(OH)]n (1) has been isolated as single crystals from the reaction of [(Me2NH2)2SeO4] and Me3SnCl in methanol. In the solid state, compound 1 was characterized by X-ray diffraction analysis, Fourier transform-infrared spectroscopy, and elemental analysis. 1 crystallizes in the orthorhombic system space group Pbca with a=11.0231(2) Å, b=16.3461(3) Å, c=20.9945(4) Å, α=β=γ=90°, V=3782.89(12) Å3, and Z=8. Its structure can be described as a polymeric zigzag chain based on Me3Sn moieties linked by tridentate selenate anions. Pendant (Me3Sn)2OH groups are also connected to the chain, according to a syndiotactic organization, and…
rac-11-Selena-12,13-diazabicyclo[10.3.0]pentadeca-10a(13a),12-dien-1-ol
2021
The title compound, C12H20N2OSe, crystallizes in strands of enantiomeric molecules connected via O—H...N hydrogen bonds. There are only slight deviations from an ideal gauche conformation in the decamethylene chain, indicating just a little strain.
rac-12-Selena-13,14-diazatricyclo[9.3.0.02,4]tetradeca-11,13-diene
2020
The centrosymmetric crystal structure of the title compound, C11H16N2Se, is built up from alternating strands of (R,R)- and (S,S)-enantiomers. These strands, which propagate along the c-axis direction, are composed of homochiral molecules related to each other by twofold screw axes. The shape of the molecule is an almost planar unit around the selenadiazole ring with a hexamethylene chain as an arched handle.
A no-carrier-added 72Se/72As radionuclide generator based on distillation
2004
Abstract Arsenic-72 is a positron emitting isotope with promising properties for syntheses of 72As-labelled radiopharmaceuticals for future application in positron emission tomography. This work describes the radiochemical separation of no-carrier-added 72Se from cyclotron irradiated germanium targets and the development of a 72Se/72As radionuclide generator, avoiding the addition of any selenium carrier. Using a vertical quartz tube device, no-carrier-added 72As is nearly quantitatively released from various chloride salt solutions containing 72Se within 10 min at a temperature of 100 °C in an HCl gas flow. The kinetics of the 72Se/72As isotope generator has been studied in relation to tem…
Automatizēta weblapu testēšanas sistēma
2021
Šis dokuments ir Latvijas Universitātes Datorikas fakultātes kursa “Kvalifikācijas darbs” (DatZR003) ietvaros izstrādātās automatizēta weblapas testēšanas sistēma projekta dokumentācija. Izmantojot selenium, capybara, cucumber, sistēma spēs veikt automatizētus weblapas testus funkcionalitātes pārbaudei un uzradīt testēšanas rezultātus.
Plasma selenium levels and oxidative stress biomarkers: a gene-environment interaction population-based study.
2014
The role of selenium exposure in preventing chronic disease is controversial, especially in selenium-repleted populations. At high concentrations, selenium exposure may increase oxidative stress. Studies evaluating the interaction of genetic variation in genes involved in oxidative stress pathways and selenium are scarce. We evaluated the cross-sectional association of plasma selenium concentrations with oxidative stress levels, measured as oxidized to reduced glutathione ratio (GSSG/GSH), malondialdehyde (MDA), and 8-oxo-7,8-dihydroguanine (8-oxo-dG) in urine, and the interacting role of genetic variation in oxidative stress candidate genes, in a representative sample of 1445 men and women…
Correlations of blood selenium with hematological parameters in West German adults.
1988
The serum selenium and the whole blood selenium of 72 healthy persons (47 women, 25 men) was determined. There exist sex specific differences of the whole blood selenium between men (98 +/- 19 micrograms Se/L) and women (89 +/- 17 micrograms Se/L). The serum selenium did not show sex specific differences, but sex specific differences are found if the total amount of extracellular selenium is calculated by correction of the serum selenium with the hematocrit. Women have more extra-cellular selenium/L whole blood (40 +/- 8 micrograms Se) than men (36 +/- 7 micrograms Se). Men have more intraerythrocyte selenium (cellular selenium = 67 +/- 14 micrograms Se) in one L whole blood than women (52 …
Literature survey of on-line elemental speciation in aqueous solutions.
2001
The literature about the on-line speciation in water has been comprehensively studied. Critical examination of this subject reveals that a great deal of work has been performed in this area for inorganic metal species and some organic compounds. The topic studied mainly includes the speciation of chromium, selenium, copper, arsenic, lead, cadmium, mercury, iron, aluminium, nickel, tin, antimony, phosphorus, nitrogen and others. The present literature survey includes also comments about the possibilities and problems of speciation as a function of analytical steps, general strategies involved and methods proposed in the literature for each element or a series of elements.
Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion
2000
Microwave assisted pre-treatments for atomic spectrometric determination (inductive coupled plasma-optical emission spectrometry, ICP-OES or flame atomic absorption spectrometry, FAAS) of metallic elements, usually present in antidandruff shampoos, are proposed. They are based on the digestion of the sample with HNO(3) into a closed reactor, which is irradiated at 800 W for a few minutes. Selenium was determined by ICP-OES. The limit of detection was 0.11 mg l(-1); the relative standard deviation (R.S.D.) for the selenium content in the samples was in the 0.6-3.6% range. The results obtained were in agreement with the label contents and the recovery of the proposed method was in the 100-106…