Search results for "selenium"
showing 10 items of 178 documents
Mo 3 Q 7 (Q = S, Se) Clusters Containing Dithiolate/Diselenolate Ligands: Synthesis, Structures, and Their Use as Precursors of Magnetic Single‐Compo…
2013
The coordination chemistry of dithiolene and diselenolene ligands towards the all-selenium [Mo3Se7Br6]2– dianion has been investigated. Complexes (nBu4N)2[Zn(dmit)2] (dmit = 1,3-dithia-2-thioxo-4,5-dithiolate) and (nBu4N)2[Zn(dsit)2] (dsit = 1,3-dithia-2-thioxo-4,5-diselenolate) were employed as ligand precursors. The (nBu4N)2[Zn(dmit)2] complex in acetonitrile at reflux showed unexpected reactivity with [Mo3Se7Br6]2– dianion in which the inner Se atoms were replaced by S (all but the μ3-Se atom) to afford a series of mixed chalcogen [Mo3Se7–xSx(dmit)3]2– (x = 0–6) dianions. Reaction of the [Mo3S4Se3Br6]2– dianion with (nBu4N)2[Zn(dmit)2] under similar conditions also produced a mixed dmit-…
Animal Models of Stress - Current Knowledge and Potential Directions
2021
Finding new therapies and new antidepressant agents is of high clinical priority given that many cases of depressive disorder do not respond to conventional monoaminergic antidepressants such as selective serotonin reuptake inhibitors, tricyclic antidepressants, and monoamine oxidase inhibitors The authors demonstrated that electroacupuncture and fluoxetine, a second-generation antidepressant categorized as a selective serotonin reuptake inhibitor (Perez-Caballero et al , 2014), regulate the expression of key proteins in the calmodulin kinase (CAMK) signaling pathway, which are related to depression in the hippocampi of rats (Takemoto-Kimura et al , 2017;Xie et al , 2019) In a paper on “Sho…
Selenium Nanoparticles Synthesized via a Facile Hydrothermal Method
2012
Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.
Selenium and tellurium nanomaterials
2018
Abstract Over the last 40 years, the rapid and exponential growth of nanotechnology led to the development of various synthesis methodologies to generate nanomaterials different in size, shape and composition to be applied in various fields. In particular, nanostructures composed of Selenium (Se) or Tellurium (Te) have attracted increasing interest, due to their intermediate nature between metallic and non-metallic elements, being defined as metalloids. Indeed, this key shared feature of Se and Te allows us the use of their compounds in a variety of applications fields, such as for manufacturing photocells, photographic exposure meters, piezoelectric devices, and thermoelectric materials, t…
Sequential Hepatogenic Transdifferentiation of Adipose Tissue-Derived Stem Cells: Relevance of Different Extracellular Signaling Molecules, Transcrip…
2009
Adipose tissue contains a mesenchymal stein cell (MSC) population Known as adipose-derived stein cells (ASCs) capable of differentiating into different cell types. Our aim was to induce hepatic transdifferentiation of ASCs by sequential exposure to several combinations of cytokines, growth factors, and hormones. The most efficient hepatogenic protocol includes fibroblastic growth factors (FGF) 2 and 4 and epidermal growth factor (EGF) (step 1), hepatocyte growth factor (HGF), FGF2, FGF4, and nicotinamide (Nic) (step 2), and oncostatin M (OSM), dexamethasone (Dex), and insulin-tranferrin-selenium (step 3). This protocol activated transcription factors [GATA6, Hex, CCAAT/enhancer binding prot…
Selenium contents of human milk and infant formulas in Spain.
1999
The selenium content of Spanish human milk samples and different milk-based and soy-based infant formulas has been estimated by using a flow injection hydride atomic absorption spectrometric method after microwave digestion of the organic matter. Mean values of 11.4 +/- 3.7 and 10.7 +/- 4.6 ng/ml for colostrum and transitional milk, 8.4 +/- 3.4 and 5.3 +/- 1.9 ng/ml for mature milk at 1 month and up to 2 months respectively, was obtained. These values are close to those reported by others authors in Europe, and lower than the ones from the US, Japan and Korea. Selenium contents of the analyzed infants' formulas ranged from 2.7 to 9.6 ng/ml and from 1.8 to 7.5 ng/ml for soy and milk-based in…
Diastereoselective synthesis of substituted 2-phenyltetrahydropyrans as useful precursors of aryl C-glycosides via selenoetherification
2004
The cyclization of several substituted 5-phenyl-pent-4-en-1-ols with selenium electrophiles along some mechanistic considerations is discussed. In particular, an efficient diastereoselective synthesis of a 2,3,5,6-tetrasubstitued tetrahydropyran is reported. These findings open an interesting approach: the use of chiral selenium electrophiles for cyclization of chiral substrates. The cyclized products are useful starting material for the synthesis of D- or L-aryl C-glycosides.
ChemInform Abstract: X-Ray Powder Structure Determination and Thermal Behavior of a New Modification of Pb(II) Selenite.
2010
The crystal structure of a new polymorphic form of lead(II) selenite (PbSeO3) was solved directly from conventional X-ray powder diffraction data. Direct methods and Rietveld refinement techniques were used for the structure determination. The compound crystallizes in the monoclinic space group P21/c (no. 14) with cell dimensions a = 9.1587(1) A, b = 8.0902(1) A, c = 8.7932(1) A, β = 103.032(1)°, and V = 634.76(2) A3. The final refinement gave background excluded Rp = 6.22%, Rwp = 8.81%, and RB = 2.16% by using 45 structural and 15 profile parameters with 10 atoms in an asymmetric unit. The three-dimensional structure consists of 9-coordinated lead atoms, which are linked by three bidentate…
Tunable photoluminescence properties of selenium nanoparticles: biogenic versus chemogenic synthesis
2020
Abstract Various technological and biomedical applications rely on the ability of materials to emit light (photoluminescence [PL]), and, among them, metal nanoparticles (NPs) and semi-conductor Quantum Dots (QDs) represent ideal candidates as sensing probes and imaging tools, portraying better PL features than conventional organic dyes. However, the knowledge of PL behavior of semiconductor NPs – i.e., selenium; SeNPs – is still in its infancy, especially for those synthesized by microorganisms. Considering the essential role played by biogenic SeNPs as antimicrobial, anticancer, and antioxidant agents, or food supplements, their PL properties must be explored to take full advantage of them…
Development of quadrupole collectivity in the neutron-rich Ni, Zn, Ge, and Se isotopes
2003
An experiment was performed to study the collective properties of neutron-rich Ni, Zn, Ge, and Se isotopes. Of particular interest is the vicinity of the N = 50 and Z = 28 shell closures. For most neutron-rich nuclei in this region of the chart of nuclei the B(E2) values of the transitions from the ground to the first excited 2+ states are unknown. This information would give valuable insight into the changes in nuclear structure when going to more neutron-rich nuclei.