Bibliografie tematiche / Selenium

Letteratura scientifica selezionata sul tema "Selenium"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 7 luglio 2024

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Articoli di riviste sul tema "Selenium"

Zhao, Xiaodan, e Lihao Liao. "Modern Organoselenium Catalysis: Opportunities and Challenges". Synlett 32, n. 13 (11 maggio 2021): 1262–68. http://dx.doi.org/10.1055/a-1506-5532.

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AbstractOrganoselenium catalysis has attracted increasing interest in recent years. This Cluster highlights recent key advances in this area regarding the functionalization of alkenes, alkynes, and arenes by electrophilic selenium catalysis, selenonium salt catalysis, selenium-based chalcogen-bonding catalysis, and Lewis basic selenium catalysis. These achievements might inspire and help future research.1 Introduction2 Electrophilic Selenium Catalysis3 Selenonium Salt Catalysis4 Selenium-Based Chalcogen-Bond Catalysis5 Lewis Basic Selenide Catalysis6 Conclusion

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Taskinen, Pekka, Sonja Patana, Petri Kobylin e Petri Latostenmaa. "Oxidation Mechanism of Copper Selenide". High Temperature Materials and Processes 33, n. 5 (29 settembre 2014): 469–76. http://dx.doi.org/10.1515/htmp-2013-0097.

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AbstractThe oxidation mechanism of copper selenide was investigated at deselenization temperatures of copper refining anode slimes. The isothermal roasting of synthetic, massive copper selenide in flowing oxygen and oxygen – 20% sulfur dioxide mixtures at 450–550 °C indicate that in both atmospheres the mass of Cu2Se increases as a function of time, due to formation of copper selenite as an intermediate product. Copper selenide oxidises to copper oxides without formation of thick copper selenite scales, and a significant fraction of selenium is vaporized as SeO2(g). The oxidation product scales on Cu2Se are porous which allows transport of atmospheric oxygen to the reaction zone and selenium dioxide vapor to the surrounding gas. Predominance area diagrams of the copper-selenium system, constructed for selenium roasting conditions, indicate that the stable phase of copper in a selenium roaster gas with SO2 is the sulfate CuSO4. The cuprous oxide formed in decomposition of Cu2Se is further sulfated to CuSO4.

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Kim, Seung Jo, Min Chul Choi, Jong Min Park e An Sik Chung. "Antitumor Effects of Selenium". International Journal of Molecular Sciences 22, n. 21 (31 ottobre 2021): 11844. http://dx.doi.org/10.3390/ijms222111844.

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Functions of selenium are diverse as antioxidant, anti-inflammation, increased immunity, reduced cancer incidence, blocking tumor invasion and metastasis, and further clinical application as treatment with radiation and chemotherapy. These functions of selenium are mostly related to oxidation and reduction mechanisms of selenium metabolites. Hydrogen selenide from selenite, and methylselenol (MSeH) from Se-methylselenocyteine (MSeC) and methylseleninicacid (MSeA) are the most reactive metabolites produced reactive oxygen species (ROS); furthermore, these metabolites may involve in oxidizing sulfhydryl groups, including glutathione. Selenite also reacted with glutathione and produces hydrogen selenide via selenodiglutathione (SeDG), which induces cytotoxicity as cell apoptosis, ROS production, DNA damage, and adenosine-methionine methylation in the cellular nucleus. However, a more pronounced effect was shown in the subsequent treatment of sodium selenite with chemotherapy and radiation therapy. High doses of sodium selenite were effective to increase radiation therapy and chemotherapy, and further to reduce radiation side effects and drug resistance. In our study, advanced cancer patients can tolerate until 5000 μg of sodium selenite in combination with radiation and chemotherapy since the half-life of sodium selenite may be relatively short, and, further, selenium may accumulates more in cancer cells than that of normal cells, which may be toxic to the cancer cells. Further clinical studies of high amount sodium selenite are required to treat advanced cancer patients.

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AVOSCAN, L., H. KHODJA, M. CARRIÈRE, J. COVÈS e B. GOUGET. "PIXE ANALYSES OF THE SOLUBLE AND MEMBRANE SE-CONTAINING PROTEINS EXTRACTED FROMCUPRIAVIDUS METALLIDURANSCH34 AFTER SELENIUM OXIDES CHALLENGE". International Journal of PIXE 18, n. 03n04 (gennaio 2008): 91–99. http://dx.doi.org/10.1142/s0129083508001430.

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The soil bacterium Cupriavidus metallidurans CH34 resist selenite by reducing it into the insoluble and less toxic elemental selenium. Two mechanisms of reduction of selenium oxides in C. metallidurans CH34 were highlighted: assimilation leading to organic species and detoxification leading to precipitation of selenite in nanoparticules of elemental selenium. The alkyl selenide detected as an intermediate product during assimilation of selenite or as the major accumulated chemical form during assimilation of selenate was identified as selenomethionine.Soluble and membrane proteins were extracted from C. metallidurans CH34 submitted to selenium oxides challenge. After separation by SDS-PAGE, µPIXE analyses were used for Se identification and quantification at a micrometer scale. The profiles of Se distribution in the different samples suggest a non-specific incorporation of selenium probably reflecting the incorporation of selenomethionin in place of the naturally occurring methionin.

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Poluboyarinov, P. A., D. G. Elistratov e V. I. Shvets. "METABOLISM AND MECHANISM OF TOXICITY OF SELENIUM-CONTAINING SUPPLEMENTS USED FOR OPTIMIZING HUMAN SELENIUM STATUS". Fine Chemical Technologies 14, n. 1 (28 febbraio 2019): 5–24. http://dx.doi.org/10.32362/2410-6593-2019-14-1-5-24.

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The work presents a review devoted to the metabolism and the mechanism of toxicity of seleniumcontaining supplements: elemental selenium, sodium selenite, diacetophenonyl selenide, selenopyrane, ebselen, dimethyl dipyrasolyl selenide and selenium-containing amino acids used for correction of selenium deficiency. Elemental selenium penetrating through cell walls, but not through transport channels demonstrates poorly predicted and difficultly regulated bioavailability. Sodium selenate is known to be the most toxic form of selenium in food. The metabolism of xenobiotic diacetophenonyl selenide resembles that of sodium selenide. The xenobiotic reacts with thiols, for instance, with the reduced form of glutathione leading to the formation of hydrogen selenide. Ebselen is not considered to be a well bioavailable form of selenium and thus possesses low toxicity. Xenobiotic selenopyrane eliminates selenium only in processes of xenobiotic liver exchange, and in our investigations - partially in acid-catalyzed hydrolysis. The metabolism of xenobiotic dimethyl dipyrasolyl selenide having low toxicity is poorly investigated. The toxicity of high doses of selenomethionine is determined by the possibility of incorporation in proteins and vitally important enzymes with dramatic changes of protein quaternary structure. The toxicity of high doses of methylselenocysteine seems to be caused by the lack of an exchange pool in the body and quick regeneration of hydrogen selenide from methylselenol which is formed as a result of enzymatic destruction of this amino acid. Also the issue of the most prospect selenium donor is discussed. The physiological compatibility, the low toxicity, the presence of an exchangeable pool in the organism, the antioxidantal properties and the simplicity of production indicate selenocystine as an optimal selenium donor.

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Ball, Sheila, e John Milne. "Studies on the interaction of selenite and selenium with sulfur donors. Part 3. Sulfite". Canadian Journal of Chemistry 73, n. 5 (1 maggio 1995): 716–24. http://dx.doi.org/10.1139/v95-091.

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Elemental selenium dissolves in sulfite solution to form selenosulfate ion: Se + SO32− = SeSO32−.The formation constants for this equilibrium at temperatures from 0 to 35 °C are reported for the first time. The isomeric thioselenate anion, SSeO32−, is not, however, produced by the reaction of sulfur with selenite nor is the selenoselenate ion, Se2O32−, formed from selenium and selenite. Selenotrithionate is formed rapidly from the reaction of selenous acid with sulfite and hydrogen sulfite according to: HSeO3− + 3 HSO3− = Se(SO3)22− + SO42− + 2H2O.Two isomers of the selenotrithionate ion are observed by Se-77 NMR and Raman spectroscopy, one with O-bonded Se, Se(OSO2)22−, and the other with S-bonded Se, Se(SO3)22−. Both isomers are formed in reactions with hydrogen sulfite but only the O-bonded isomer is formed in sulfite solutions at ambient temperatures. The Raman and Se-77 NMR spectra of the various sulphur–selenium anions formed are given and the parallel with the reactions of selenous acid and thiols is discussed. Keywords: selenium, sulfite, selenosulfate, selenotrithionate, Se-77 NMR, Raman spectroscopy, equilibria, aqueous solutions.

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Danscher, Gorm, e Meredin Stoltenberg. "Zinc-specific Autometallographic In Vivo Selenium Methods: Tracing of Zinc-enriched (ZEN) Terminals, ZEN Pathways, and Pools of Zinc Ions in a Multitude of Other ZEN Cells". Journal of Histochemistry & Cytochemistry 53, n. 2 (febbraio 2005): 141–53. http://dx.doi.org/10.1369/jhc.4r6460.2005.

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In vivo-applied sodium selenide or sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkühn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If sodium selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neurons, resulting in accumulation of zinc-selenium nanocrystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly specific tool for tracing ZEN pathways. The present review includes an update of the 1982 paper and presents evidence that only zinc ions are traced with the AMG selenium techniques if the protocols are followed to the letter.

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Anderson, Kim A., e Brandon Isaacs. "Determination of Selenium in Feeds, Premixes, Supplements, and Injectable Solutions by Hydride-Generated Inductively Coupled Plasma Atomic Emission Spectrometry". Journal of AOAC INTERNATIONAL 76, n. 4 (1 luglio 1993): 910–13. http://dx.doi.org/10.1093/jaoac/76.4.910.

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Abstract A simple method is described for the determination of 0.01-30 000 μg selenium/g sample. Selenium is present in feed supplements, premixes, mineral mixes, and injectable solution as either selenite or selenate. High concentrations of other common minerals present in these supplements are tolerated by the method. The samples are initially digested by heating with nitric acid and then boiled in a mixture of sulfuric and perchloric acids to convert all selenium species to selenate. The selenate is reduced to selenite, Se (IV), with hydrochloric acid at 95°C. The selenite in turn is then reduced by acidic sodium borohydride to hydrogen selenide, which is measured by hydride-generated inductively coupled plasma atomic emission spectrometry at 196.026 nm. The instrument detection limit for this method is 0.0005 μg Se/g sample.

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Amaratunga, W., O. Chaudry e J. Milne. "Studies on the interaction of selenite and selenium with sulphur donors. Part 1. 2-Mercaptoethanol". Canadian Journal of Chemistry 72, n. 4 (1 aprile 1994): 1165–70. http://dx.doi.org/10.1139/v94-149.

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Raman spectroscopy and proton and 77Se NMR have been used to show that selenous acid reacts with 2-mercaptoethanol (HOC2H4SH), according to Ganther's reaction (H.E. Ganther, Biochemistry, 7, 2898 (1968)).[Formula: see text]The bis(hydroxyethylthio)selenide decomposes readily in strongly acidic and moderately basic solution to selenium and disulfide,[Formula: see text]Selenium dissolves in excess hydroxyethylmercaptide to give the catenated anion, HOC2H4SSe−[Formula: see text]Air oxidation of this equilibrium mixture yields disulfide and selenium. Formation of the hydroxyethylthioselenide is endothermic (ΔH = 0.66 ± 0.02 kJ mol−1).

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Eom, Taejun, e Anzar Khan. "Selenium-Epoxy ‘Click’ Reaction and Se-Alkylation—Efficient Access to Organo-Selenium and Selenonium Compounds". Chemistry 2, n. 4 (5 ottobre 2020): 827–36. http://dx.doi.org/10.3390/chemistry2040054.

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This work establishes the ‘click’ nature of the base-catalyzed oxirane ring opening reaction by the selenolate nucleophile. The ‘click’-generated ß-hydroxy selenide can be alkylated to afford cationic selenium species. Hemolytic studies suggest that selenonium cations do not lyse red blood cells even at high concentrations. Overall, these results indicate the future applicability of the developed organo-selenium chemistry in the preparation of a new class of cationic materials based on the seleno-ether motif.

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Più fonti

Tesi sul tema "Selenium"

Subirana, Manzanares Maria Àngels. "Selenium biofortification of wheat: Distribution and spatially resolved selenium speciation by synchrotron-based techniques". Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666886.

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El seleni és un micronutrient essencial pels humans. Té diversos rols en la salut i per tant, el seu consum a nivells òptims és altament beneficial. Tot i així, 500-1000 milions de persones al món pateixen dèficit de seleni, degut als baixos nivells de seleni als sòls del camps de conreu. La biofortificació dels cultius amb fertilitzants rics en seleni és la manera més efectiva de contrarestar la deficiència de seleni. Tot i així, la especiació de seleni és fonamental: les plantes són capaces de transformar el seleni inorgànic del sòl, com els ions selenit i selenat, en seleni orgànic, com els selenoamino àcids, que són menys tòxics i més biodisponibles. El blat és el cereal més consumit al món i és capaç de tolerar i acumular més de 100 mg de Se per Kg de pes sec, i per tant, és un candidat adequat per la biofortificació amb seleni per produir un aliment funcional. El seleni en el blat es troba en forma de cinc espècies principals: selenit, selenat, selenometionina, metilselenocisteina i selenocistina. A la present tesis, el contingut i la distribució d’aquestes espècies en el blat s’ha determinat amb el tàndem de cromatografia líquida d’alta precisió (HPLC-ICP-MS) després de una apropiada digestió enzimàtica de la mostra, i per espectroscòpia d’absorció de raig-X (XAS) amb radiació de sincrotró, entre d’altres tècniques. La especiació i la concentració de seleni, les condicions de creixement de la planta, i el temps in que el seleni és aplicat a la planta, defineixen el grau d’absorció, metabolització i distribució de seleni a través dels diferent òrgans de la planta. El selenit es redueix ràpidament a les arrels, i per tant s’acumula en els teixits subterranis. D’altra banda, el selenat és molt mòbil a través del xilem de la planta i la seva translocació és més ràpida que la seva reducció, i per tant s’acumula a la part aèria. La aplicació d’altes concentracions de seleni pot resultar en l’acumulació excessiva als teixits, provocant estrès i toxicitat, fent decréixer la producció de biomassa a la planta i reduint el rendiment del gra. Tan mateix, la fitotoxicitat en el blat pot ser reduïda amb la aplicació del seleni a la florescència, i tot i així aconseguint un enriquiment del gra i una metabolització del seleni similars. El selenit va ser casi completament reduït a espècies orgàniques, principalment a les arrels, on la toxicitat induïda va produir un ambient altament oxidant a la planta, i per tant va resultar en una acumulació de seleni orgànic en forma de selenocistina. En contra, el selenat va mostrar una metabolització més lenta i una acumulació significativa en forma inorgànica a les tiges i fulles, tot i que en el gra el seleni es va trobar com a espècies orgàniques en forma de selenometionina, la qual es pot incorporar de forma no específica a les proteïnes. D’altra banda, la aplicació de els dos anions de forma simultània va contribuir a anivellar l’enriquiment de seleni, degut a les seves vies metabòliques separades. La mescla va causar una distribució més equilibrada de seleni en els teixits vegetals, reduint la seva fitotoxicitat, però resultant en la mateixa concentració total en el gra i uns nivells intermedis de selenometionina i selenocistina. A més, l’anàlisi espacialment resolt de la especiació als grans de blat va mostra una alta acumulació de seleni en l’embrió, el segó i l’àrea vascular pigmentada, i una baixa concentració al endosperma, que correlaciona amb la concentració de proteïnes a les diferents parts del gra. Finalment, s’ha mostrat l’efecte protector del seleni en front de la toxicitat del mercuri, la qual sembla que és deguda a la formació d’un complex proteïna-Se-Hg a les arrels. Aquest complex redueix la translocació del mercuri a les parts aèries i al gra, la mobilitat dels selenat i la reducció del selenit a les arrels, al mateix temps que afavoreix l’acumulació d’amino àcids amb la estructura de C-Se-C com la selenometionina en el gra. D’aquesta forma, el seleni pot contrarestar la fitotoxicitat del mercuri i reduir el risc en conreus exposats a sòls contaminats amb mercuri.
Selenium, as an essential micronutrient for humans, has several roles in health and thus, its intake at optimum levels is highly beneficial. However, 500-1000 million of people worldwide suffer selenium deficiency, due to the low Se levels in soils of agricultural lands. Biofortification of crops with Se-rich fertilizers is the most effective approach to counteract selenium deficiency. However, the selenium speciation is also fundamental: plants are able to transform the soil inorganic selenium, i.e. selenite and selenate ions, into organic selenium, such as selenoamino acids, which are less toxic and more bioavailable. Wheat is the most consumed cereal worldwide and is able to tolerate and accumulate over 100 mg Se per kg of dry weight, thus being a suitable candidate for Se biofortification to produce an enriched functional food. Selenium in wheat is found in the form of five major selenium species: selenite, selenate, selenomethionine, methylselenocysteine and selenocystine. In the present thesis, the content and distribution of these species in wheat was determined by the tamdem of high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) after appropriate enzymatic sample digestion, and by X-Ray Absorption Spectroscopy (XAS), using synchrotron radiation, among other techniques. The speciation and concentration of Se, the plant growth conditions and the stage in which selenium is applied to the plant define the degree of selenium uptake, metabolization and distribution through the different plant organs. Selenite is readily reduced in wheat roots, and thus, it accumulates preferentially in underground tissues; on the other hand, selenate is highly mobile through the plant xylem and its translocation is faster than its reduction, therefore accumulating in shoots. The application of high Se concentrations may result in excessive tissue accumulation, and thus, plant stress and Se-induced toxicity, decreased plant biomass production and reduced grain yield. However, wheat phytotoxicity may be reduced by the application of selenium at florescence time, but still achieving similar enrichment of grain and Se metabolization. Selenite was almost completely reduced into organic species, especially in roots, where the induced toxicity effects produced a strong oxidizing environment within the plant, thus producing a high accumulation of organic selenium in grain in the form of selenocystine. Oppositely, selenate showed slower metabolization and a significant accumulation of selenium in inorganic forms in shoots, although in grain selenium was found as organic species in the form of selenomethionine, which can be unspecifically incorporated into proteins. On the other hand, the application of both anions simultaneously contributed to balance the Se enrichment due to their separate metabolic pathways. The mixture caused a more equilibrated distribution of Se in the plant tissues, reducing its phytotoxicity, but resulting in the same total selenium concentration in grain and an intermediate amount of selenomethionine and selenocystine. Furthermore, the spatially resolved speciation analysis of wheat grains, showed high selenium accumulations in the germ, bran and pigment strand, and a low selenium concentration in the endosperm, which correlated positively with the concentration of proteins in the different parts of the grain. Finally, the protective effect of selenium against mercury toxicity was shown and it seems that it was due to the formation of a protein-Se-Hg complex in roots. This complex reduced the translocation of mercury to shoots and grain, the selenate mobility and the selenite reduction in roots, but at the same time it enhanced the accumulation of C-Se-C amino acids, such as selenomethionine, in wheat grain. As a result, selenium counteracted mercury phytotoxicity and reduced the risk in crops exposed to mercury polluted soils.

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Browne, Danielle M. "Novel selenium catalysis". Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54706/.

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This thesis describes work carried out on catalytic selenium reagents in a range of organic transformations. Four different areas have been investigated and are reported herein. Chapter 2 reports the unsuccessful development into prochiral ligands, where three different chalcogen atoms are incorporated into either a trisubstituted structure or into a crown ether ring. Then reports how these structures could attach to a metal atom and become chiral. A SSe I SeR Chapter 3 describes a range of selenium-based ligands, which has been used in the palladium allylic substitution reaction to see if there is good co-ordination between selenium and palladium and if good enantioselectivities can be achieved. Chapter 4 describes the use of seleninic acids as catalysts in a range of reactions where the most successful is used in asymmetric Baeyer-Villiger oxidations using a range of ketones with enantiotopic migrating groups. The enantioselectivities were investigated. Chiral Catalyst I I ,0 O H202 O ASe A X R O R R CH2CI2 R ' Chiral Catalyst Chapter 5 describes the successful work on catalytic selenium reagents used to convert /,y-alkenoic acids into their corresponding butenolides. The work describes the optimum conditions investigated, asymmetric version of the reaction and also investigates mechanistic aspects of the catalytic cycle. Cat - (PhSe)2 Oxidant R 0 R C00H " _J Solvent.

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Nguyen, Nu Hoai Vi School of Chemical Engineering &amp Industrial Chemistry UNSW. "Photocatalytic reduction of cadmium and selenium ions and the deposition of cadmium selenide". Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/20849.

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Titanium dioxide (TiO2) photocatalysis, which can oxidise or reduce organic and inorganic pollutants, is a developing technology for water and wastewater treatment. The current work investigates the photocatalytic reduction of cadmium and selenium species as the presence of these elements in water are of environmental concern. Although TiO2 has been widely used for the photocatalytic process, its light absorption is limited to the UV region of the solar spectrum. Hence, the current project also explores the possibility to deposit cadmium selenide (CdSe) onto TiO2 to extend the photoresponse to the visible region. This study demonstrated that cadmium (Cd(II)) could be reduced to its metallic form by photocatalysis. The choice of hole scavengers and reaction pH are of importance in determining whether the photocatalytic reduction reaction will occur. It is also essential that both Cd(II) and organic additives are adsorbed on the surface of TiO2. A mechanism for cadmium photoreduction in the presence of formate as the hole scavenger was proposed. The current investigation elucidated the mechanism for the photoreduction of selenite (Se(IV)). Selenite was found to be photoreduced to its elemental form (Se(0)) as films, by direct photoreduction of Se(IV), and as discrete particles, by the reaction between Se(IV) and selenide (Se(2-)) ions. The Se(2-) ions are believed to have been generated from the 6 electron photoreduction of Se(IV) and/or the further photoreduction of the Se(0) deposits. Photocatalytic reduction reactions of Se(IV) and selenate (Se(VI)) using different commercial TiO2 materials was also studied. The current work also successfully deposited CdSe by photocatalysis using Se-TiO2 obtained from the photoreduction of Se(IV) and Se(VI). The mechanism for CdSe deposition was clarified and attributed to the reaction of Cd(II) present in the system and the Se(2-) released from the reduction of Se(0) upon further illumination. The Se??TiO2 photocatalysts obtained from the photoreduction of different selenium precursors (Se(IV) and Se(VI)) resulted in the dominance of different morphologies of the CdSe particles. This suggests a new approach to manipulate the properties of CdSe during its formation, and hence control over electrical and optical properties of this semiconductor.

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Hendrickx, Wouter R. L. "Selenium and prostate cancer". Thesis, University of East Anglia, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.588614.

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Prostate cancer is the second most common diagnosed cancer and the third most common cause of death related to cancer among men in developed countries. Several epidemiological studies, prospective cohort studies and animal tumour models state an inverse relationship between selenium status and cancer incidence. Se- methylselenocysteine (SeMSC), present in garlic, onions, leeks and broccoli, has been shown to be the most effective anti-carcinogenic selenium form in animal models. The aim of the work presented in this thesis was to investigate the influence of selenium compounds (Se-methylselenocysteine and selenomethionine) on prostate cancer progression and metastasis using various human cell lines (LNCaP, OU145 and PC3). Standard 20 gel and SILAC (stable isotope labelling with amino acids in cell culture) proteomics were used, in combination with mass spectrometry, to identify selenium- responsive proteins. IMPOH2, GPI, EZR and RGS10 were validated by western blot, while POIA3 and 00X5 showed a selenium response under serum depleted conditions. Some proteins require more scrutinizing (galectin-1, XRCC5, TAGLN2, 00X5 and FLT) as conflicting results were obtained during validation. Preliminary analysis using 20 gel proteomics revealed galectin-1 to be selenium-responsive in PNT1A cells, although this could not be confirmed by Western blot or an in-house ELlSA. Previously, it has been shown that SeMSC decreased the expression of collagen I and increased that of collagen IV and collagen VI. A LNCaP 3D gel suspension model was developed to allow further investigation of extracellular matrix components using fluorescence microscopy. In addition, the effect of selenium exposure on the migration and invasion of PC3 cells was investigated using a transwell kinetic assay and revealed a dose response increase, especially under low baseline selenium concentrations. In order to optimize future selenium in vitro projects the dynamics of several selenium biomarkers were investigated using different conditions, enabling better comparison between cell lines and/or selenium compounds.

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Saito, Ichitaro. "Amorphous selenium photoelectric devices". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610017.

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Shahzad, Sohail Anjum. "Novel selenium-mediated cyclisations". Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54389/.

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The present work describes the selenium-mediated cyclofunctionalisations of alkenes. Three different areas are reported herein. Chapter 2 reports syntheses of several substrates for carbocyclisation reactions and use of selenium and Lewis acids resulting in various dihydronaphthalenes. These dihydronaphthalenes then acted as substrates for second ring forming reactions. This novel tandem double cyclisation comprises a carboannulation, a Friedel-Crafts reaction and a rearrangement. This cascade sequence has been proven to be a useful tool in the selective synthesis of dihydronaphthalenes and benzofluorenes from easily accessible stilbenes and provides fast access to polycyclic ring systems in a single step. Chapter 3 describes electrophilic selenium-mediated reactions which have been used to cyclise a range of /-keto esters to corresponding biaryl compounds under very mild conditions. The products were formed by a carboannulation via addition/elimination sequence and a subsequent rearrangement of range of alkyl and aryl groups. The key starting materials stilbene /-keto esters were readily prepared by Heck coupling and hydrolysis followed by condensation with potassium ethyl malonate. Chapter 4 describes work on catalytic selenium reagents with stoichiometric amount of hypervalent iodine to convert a range of stilbene carboxylic acids into their corresponding isocoumarins. The work also describes the selective synthesis of dihydroisocoumarins using diphenyl disulfide and dimethyl diselenide.

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Reiners, Roger. "Importance nutritionnelle du selenium". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR1M096.

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Gudavalli, Dileep. "Measurement of selenite reduction to elemental selenium by Stenotrophomonas maltophilia OR02". Youngstown State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1377876956.

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Andersson, André. "Selenium-Testing as a Service". Thesis, Linköpings universitet, Interaktiva och kognitiva system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132372.

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Selenium has been a method to test web applications for over a decade, it is interacting directly with the browser and has gained support from both browsers and the community. With the growing amount of browsers, mobile devices and operating systems which a web application is expected to work with, services providing these systems for testing web applications against has gained interest. These services provide testing as a service (TaaS), and runs Selenium-tests in the cloud. This research tried to compare the different services with each other in regard to flexibility, cost, simplicity and reliability. I have also tried to see differences between running the tests locally and using these services. The results showed that there are some differences between the services, and the one best suited might depend on the web application.

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Zhong, Liangwei. "Selenium in mammalian thioredoxin reductase /". Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4243-9/.

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Più fonti

Libri sul tema "Selenium"

Preedy, Victor R., a cura di. Selenium. Cambridge: Royal Society of Chemistry, 2015. http://dx.doi.org/10.1039/9781782622215.

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Michalke, Bernhard, a cura di. Selenium. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95390-8.

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Schrauzer, G. N., a cura di. Selenium. Totowa, NJ: Humana Press, 1988. http://dx.doi.org/10.1007/978-1-4612-4606-0.

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Hatfield, Dolph L., Ulrich Schweizer, Petra A. Tsuji e Vadim N. Gladyshev, a cura di. Selenium. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41283-2.

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Hatfield, Dolph L., Marla J. Berry e Vadim N. Gladyshev, a cura di. Selenium. Boston, MA: Springer US, 2006. http://dx.doi.org/10.1007/0-387-33827-6.

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Hatfield, Dolph L., a cura di. Selenium. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1609-5.

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Hatfield, Dolph L., Marla J. Berry e Vadim N. Gladyshev, a cura di. Selenium. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-1025-6.

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Organisation, International Labour, International Program on Chemical Safety., United Nations Environment Programme e World Health Organization, a cura di. Selenium. Geneva: World Health Organization, 1987.

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Oldfield, J. E. Selenium world atlas. Grimbergen, Belgium: Selenium-Tellurium Development Association, 1999.

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Pilon-Smits, Elizabeth A. H., Lenny H. E. Winkel e Zhi-Qing Lin, a cura di. Selenium in plants. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56249-0.

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Capitoli di libri sul tema "Selenium"

Ochsenkühn-Petropoulou, Maria, Fotios Tsopelas, Lena Ruzik, Katarzyna Bierła e Joanna Szpunar. "Selenium and Selenium Species". In Metallomics, 129–72. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694907.ch6.

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Vasiliu, Monica, e David A. Dixon. "Selenium". In Encyclopedia of Earth Sciences Series, 1–2. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-39193-9_29-1.

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Vasiliu, Monica, e David A. Dixon. "Selenium". In Encyclopedia of Earth Sciences Series, 1326–28. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-39312-4_29.

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Crowson, Phillip. "Selenium". In Minerals Handbook 1992–93, 219–23. London: Palgrave Macmillan UK, 1992. http://dx.doi.org/10.1007/978-1-349-12564-7_34.

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Antonyak, Halyna, Ruslana Iskra, Natalia Panas e Roman Lysiuk. "Selenium". In Trace Elements and Minerals in Health and Longevity, 63–98. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-03742-0_3.

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Crowson, Phillip. "Selenium". In Minerals Handbook 1994–95, 229–33. London: Palgrave Macmillan UK, 1994. http://dx.doi.org/10.1007/978-1-349-13431-1_36.

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Crowson, Phillip. "Selenium". In Minerals Handbook 1996–97, 312–19. London: Palgrave Macmillan UK, 1996. http://dx.doi.org/10.1007/978-1-349-13793-0_37.

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Rayman, Margaret P. "Selenium". In Bioactive Compounds and Cancer, 411–48. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-627-6_19.

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Batistatou, Anna, e Konstantinos Charalabopoulos. "Selenium". In Encyclopedia of Cancer, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-27841-9_5222-3.

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Neal, R. H. "Selenium". In Heavy Metals in Soils, 260–83. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-1344-1_12.

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Atti di convegni sul tema "Selenium"

Zenkov, A. V., E. S. Sushko, A. B. Sarangova e N. S. Kudryasheva. "ASSESSMENT OF THE BACTERIAL BIOLUMINESCENCE POTENTIAL FOR MONITORING THE SELENIUM COMPOUND SOLUTIONS TOXICITY, DETOXIFICATION AND ELEMENTARY SELENIUM SYNTHESIS". In X Международная конференция молодых ученых: биоинформатиков, биотехнологов, биофизиков, вирусологов и молекулярных биологов — 2023. Novosibirsk State University, 2023. http://dx.doi.org/10.25205/978-5-4437-1526-1-177.

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Impact of sodium selenite (Na2 SeO3 ) (as a selenium compound) on bacterial bioluminescence and Photobacterium phosphoreum selenium oxyanions biotransformation to elementary selenium was investigated. Luminous bacteria were demonstrated to be a prospective tool for selenium compounds’ toxicity monitoring, detoxification of water solutions and elementary selenium synthesis.

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Galchenko, E. I., I. I. Seregina e O. V. Eliseeva. "The effect of foliar selenium fertilization of leaf radish plants on the quality of finished products". In II All-Russian scientific conference with international participation "Achievements of science and technology". Krasnoyarsk Science and Technology City Hall, 2023. http://dx.doi.org/10.47813/dnit-ii.2023.7.47-53.

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The influence of foliar selenium fertilization of vegetative plants of leaf radish on the quality of finished products is considered. The object of the study is a variety of leaf radish VR–Tv-28 of South Korean selection. Scheme of experience: NPK (background) – control option; NPK + BUT Se 0.0005%; NPK + BUT Se 0.001%; NPK + BUT Se 0.002%; (selenium concentrations). The repetition is threefold. Macro fertilizer used as a background and introduced into the soil during sowing in an amount of 30 g/m2 is nitroammophoska. The plants were treated with a solution of sodium selenite by spraying in the phase of mass molting of the root. In the background versions, the plants were treated with distilled water. It was found that selenium fertilization in the form of non-root treatment of vegetative plants of leaf radish of South Korean selection (variety VR-Tv-28) with sodium selenite solution did not affect the content of dry matter and dry soluble substances, but caused a decrease in the content of ascorbic acid in plants and a decrease in the content of nitrates in the leaves of leaf radish of this variety. It was determined that the use of this type of selenium fertilization of leaf radish plants led to an increase in the concentration of selenium in the leaves by 1.2-1.8 times compared with the control and did not affect its accumulation in the roots.

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Tang, Ying, Sharad Yedave, Joseph Despres, Oleg Byl e Joseph Sweeney. "Hydrogen Selenide (H2Se) Dopant Gas for Selenium Implantation". In 2016 21st International Conference on Ion Implantation Technology (IIT). IEEE, 2016. http://dx.doi.org/10.1109/iit.2016.7882878.

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IVANOV, D. K., N. P. OSIPOVICH, S. K. POZNYAK e E. A. STRELTSOV. "ELECTROCHEMICAL DEPOSITION OF METAL SELENIDE CLUSTERS ON SELENIUM SURFACE". In Physics, Chemistry and Application of Nanostructures - Reviews and Short Notes to Nanomeeting 2003. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812796738_0086.

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Mishra, P. "Prediction of Electronic and Optical Properties of Boron Selenide BSe (2H) monolayer based on First-Principles". In Functional Materials and Applied Physics. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901878-9.

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Abstract. In this study, we examined some properties of 2D monolayer of Boron selenide BSe (2H) such as structural, electronic and optical properties. The BSe (2H) monolayer has an indirect bandgap of 2.62eV from Γ to M points. We explored from density of states (DOS), in valance band close to fermi level 4p state of selenium (Se) atom is hybridized with 2p state of B atom, but close to lower part of conduction band 2p state of boron (B) atom is ascendant over the 4p state of selenium atom. We have also calculated optical parameter like imaginary and real component of dielectric function, refractive index, absorption coefficient from random phase approximation method(RPA).

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Lee, Denny L. Y. "Selenium detector with a grid for selenium charge gain". In Medical Imaging, a cura di Michael J. Flynn. SPIE, 2005. http://dx.doi.org/10.1117/12.594623.

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Kharchenko, V. A., Z. A. Amagova, M. S. Antoshkina e A. A. Koshevarov. "Leafy vegetables and spicy flavoring plants, biofortified with selenium in production of functional spices". In Agrobiotechnology-2021. Publishing house of RGAU - MSHA, 2021. http://dx.doi.org/10.26897/978-5-9675-1855-3-2021-159.

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Biochemical parameters and levels of selenium accumulation in selenium biofortified and non-fortified dill, parsley, chervil, celery, A.ursinum, A.scheoprasum and A.sativum were determined. Prospects of selenium biofortified vegetables for production of functional food products are discussed.

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Razak, Rosnisa Abdull, e Fairul Rizal Fahrurazi. "Agile testing with Selenium". In 2011 5th Malaysian Conference in Software Engineering (MySEC). IEEE, 2011. http://dx.doi.org/10.1109/mysec.2011.6140672.

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Kongsli, Vidar. "Security testing with Selenium". In Companion to the 22nd ACM SIGPLAN conference. New York, New York, USA: ACM Press, 2007. http://dx.doi.org/10.1145/1297846.1297927.

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Poulain, Agnieszka, Laurent Charlet, Alejandro Fernandez-Martinez e Sara Goberna Ferron. "Magnetite-catalyzed selenium reduction". In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.6776.

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Rapporti di organizzazioni sul tema "Selenium"

Sytkowski, Arthur. Selenium and Breast Cancer Growth. Fort Belvoir, VA: Defense Technical Information Center, luglio 2005. http://dx.doi.org/10.21236/ada454230.

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Thompson, Henry J. Selenium and Breast Cancer Chemoprevention. Fort Belvoir, VA: Defense Technical Information Center, agosto 2002. http://dx.doi.org/10.21236/ada411287.

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Atalay, A. Selenium speciation in ground water. Office of Scientific and Technical Information (OSTI), luglio 1990. http://dx.doi.org/10.2172/7107624.

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Thompson, Henry J. Selenium and Breast Cancer Chemoprevention. Fort Belvoir, VA: Defense Technical Information Center, dicembre 2006. http://dx.doi.org/10.21236/ada467942.

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Volpe, A. M., e B. K. Esser. Selenium isotope geochemistry: A new approach to characterizing the environmental chemistry of selenium. Final report. Office of Scientific and Technical Information (OSTI), febbraio 1997. http://dx.doi.org/10.2172/505158.

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Atalay, A., e K. J. Koll. Selenium transformation in coal mine spoils. Office of Scientific and Technical Information (OSTI), settembre 1990. http://dx.doi.org/10.2172/7205343.

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Lu, Junxuan. Angiogenesis and Cancer Prevention by Selenium. Fort Belvoir, VA: Defense Technical Information Center, giugno 2001. http://dx.doi.org/10.21236/ada395671.

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Saroff, L., W. Lipfert e P. D. Moskowitz. Mercury-selenium interactions in the environment. Office of Scientific and Technical Information (OSTI), febbraio 1996. http://dx.doi.org/10.2172/211348.

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Lu, Junxuan. Angiogenesis and Cancer Prevention by Selenium. Fort Belvoir, VA: Defense Technical Information Center, giugno 2002. http://dx.doi.org/10.21236/ada411465.

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Lu, Junxuan. Angiogenesis and Cancer Prevention by Selenium. Fort Belvoir, VA: Defense Technical Information Center, giugno 2000. http://dx.doi.org/10.21236/ada384802.

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