Search results for "selenium"
showing 10 items of 178 documents
Ebselen prevents chronic alcohol-induced rat hippocampal stress and functional impairment
2007
Background: Most of the previously published data suggest a role for oxidative or nitrosative stress in ethanol-induced nervous system damage. Moreover, ethanol is able to impair learning abilities in adult mammalian brain, a process suggested to be directly related to hippocampal neurogenesis. Ebselen, a synthetic compound with antioxidant properties, is able to prevent ethanol-induced impairment of neurogenesis in adult rats. The aim of the present work was to further demonstrate the ability of ebselen to prevent biochemical alterations, and preserve long-term potentiation (LTP) and learning abilities, in the hippocampus of chronic alcoholic adult rats. Methods: Biochemical markers of oxi…
Investigations concerning the COX/5-LOX inhibiting and hydroxyl radical scavenging potencies of novel 4,5-diaryl isoselenazoles
2007
The aim of this study was to investigate 4,5-diaryl isoselenazoles as multiple target non-steroidal anti-inflammatory drugs (MTNSAIDs) which can intervene into the inflammatory processes via different mechanisms of action creating a new class of compounds. Here we describe the synthesis of COX/LOX inhibitors which additionally reduce the level of reactive oxygen species, such as hydroxyl radicals which are well known for supporting inflammation processes in Parkinson's disease, Alzheimer's disease and rheumatoid arthritis.
Biogenic Selenium Nanoparticles: A Fine Characterization to Unveil Their Thermodynamic Stability
2021
Among the plethora of available metal(loid) nanomaterials (NMs), those containing selenium are interesting from an applicative perspective, due to their high biocompatibility. Microorganisms capable of coping with toxic Se-oxyanions generate mostly Se nanoparticles (SeNPs), representing an ideal and green alternative over the chemogenic synthesis to obtain thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole that impairs the exploitation of biogenic SeNP full potential. Here, spherical and thermodynamically stable SeNPs were produced by a metal(loid) tolerant Mic…
Electrodeless HF-lamps as UV and VUV light sources
2002
The paper is devoted to problems of employment of high- frequency electrodeless lamps as ultra violet (UV) and vacuum ultra violet (VUV) light sources. Some aspects of lamp preparation technology for UV and VUV are considered. The technology, developed in our laboratory, allows to prepare HFEL-s filled with wide spread of chemical elements. Our experience shows that most important filling elements for UV and VUV spectral regions are Zn, Cd, Hg, Se, As, Sn and Pb, Sb, Bi, Tl, Te, I, H, Hg-Cd, Hg-Zn, Se-Te. The requirements for generators are discussed. Some important spectral characteristics of lamp examples are presented.
Metal speciation in biological fluids — a review
1996
The literature on the speciation of metal ions in biological fluids is comprehensively reviewed. Critical examination on this subject reveals that major work has been done in blood and urine. Speciation in materials like milk has not yet been widely studied. On the other hand, only few references could be found on sweat, saliva, cell lysate, cerebrospinal, seminal, tear and bronchoalveolar fluids. The topics studied for these fluids were mainly the speciation of arsenic, mercury, aluminium and selenium. Work on the speciation of other elements like zinc, chromium, cadmium, lead, copper, iron etc. have also been carried out in such matrices. The present literature survey includes also a crit…
The preparation of four- and six-membered chalcogenametallacyclic derivatives of group 4 metallocenes
1989
Abstract Four-membered metallacycles [(RC 5 H 4 ) 2 M(μ-E)] 2 (M = Zr, Hf; 1 , E = Se; 2 , E = S) were obtained by UV irradiation of dialkyl- or diaryl-metallocenes and equimolecular amounts of elemental chalcogen, but this method works only for bulky R groups. A more general route to compounds 1 and 2 involves the reaction of metallocene dichloride with chalcogenide anions. Six-membered metallacyclohexasulfanes (t-BuC 5 H 4 ) 2 MS 5 ( 3 , M = Zr, Hf) are obtained rather than compounds 2 when an excess of sulfur is used in the photolytic experiments, whereas compounds 1 were still formed when an excess of selenium was used. The observed difference is explained in terms of the solubility of …
Thermal stability and reaction of chalcogen-containing metallocenic compounds with elemental chalcogens
1989
Abstract Dissymmetrical four-membered bimetallocenacycles (t-BuC 5 H 4 ) 2 M(μ-S) 2 M′-(RC 5 H 4 ) 2 (M, M′ = Zr, Hf; R = H, t-Bu) have been prepared and found to give redistribution products in solution at 190°C; identification of these products shows that the reaction involves exclusive cleavage of a metal-sulfur bond. Elemental sulfur and selenium react with chalcogen-containing complexes. The reaction is shown to involve the introduction of chalcogenic species in place of the σ-ligands of the complex to give either four-membered bimetallic complexes or catenated pentachalcogen metallocenic compounds. Some examples of insertion of sulfur and tellurium into the zirconium-methyl bond are a…
Metallocenes of Nb and Ta with η2-Se2H, SeH, and Se Ligands – Crystal Structures of [Cp′2Ta(SeH)H2] and [Cp′2Ta(=Se)H·W(CO)5] (Cp′ =tBuC5H4)
1999
The reactions of [Cp#2NbBH4] (1) [Cp# = C5Me5 (Cp*) or C5Me4Et] and [Cp′2TaH3] (Cp′ = tBuC5H4) with elemental selenium give complexes of the general composition [Cp2MSe2H]. These exist in three isomeric forms, A–C, depending on the metal and the chalcogen. [Cp#2NbSe2H] (2) incorporates the novel η2-Se2H ligand (C), which is labile when exposed to light. Solutions of 2(Cp*) can be converted into [Cp*2NbSe2H] (3), which exists in two isomeric forms A or B, along with [Cp*2NbSe3H] (4) and [Cp*2NbO2H] (5). [Cp′2Ta(η2-Se2)H] (6) is the only isomer found for the Ta system. Se abstraction by means of P(OEt)3 gives [Cp′2Ta(=Se)H] (7). Complex 7 can be reduced with Na/Hg and subsequently hydrolysed …
Experimental and Theoretical Investigations of Structural Trends for Selenium(IV) Imides and Oxides: X-ray Structure of Se3(NAd) 2
2004
The thermal decomposition of Se(NAd)(2) (Ad = 1-adamantyl) in THF was monitored by (77)Se NMR and shown to give the novel cyclic selenium imide Se(3)(NAd)(2) as one of the products. An X-ray structural determination showed that Se(3)(NAd)(2) is a puckered five-membered ring with d(Se-Se) = 2.404(1) A and |d(Se-N)| = 1.873(4) A. On the basis of (77)Se NMR data, other decomposition products include the six-membered ring Se(3)(NAd)(3), and the four-membered rings AdNSe(micro-NAd)(2)SeO and OSe(micro-NAd)(2)SeO. The energies for the cyclodimerization of E(NR)(2) and RNEO (E = S, Se; R = H, Me, (t)Bu, SiMe(3)), and the cycloaddition reactions of RNSeO with E(NR)(2), RNSO(2) with Se(NR)(2), and S…
"Sweet Chemistry": a Green Way for Obtaining Selenium Nanoparticles Active against Cancer Cells
2017
We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/…