• Michael Nazarkovsky added an answer:
    How do I convert the selenium dioxide to selenious acid?

    See above.

    Michael Nazarkovsky · Chuiko Institute of Surface Chemistry, Kiev, Ukraine

    To all previous ones: Mr. Selvaraj asked about a detailed description of the acid sythesis.

    SeO2 (110.96) + H2O (18.02) → H2SeO3 (128.98)

    The preparation technique as follows: dissolve SeO2 in little amount of water (in porcelain mortar), thereupon the evaporation of the solution follows. NB: this solution found in a mortar must be avoided ingressing of dust in the course of the evaporation.

    The evaporation is carried out on the bain-marie until the crystallization occurs.

    After cooling H2SeO3 formed has to be filtered using a glass filter and recrystallized in water once again to provide an appropriate purity of the product.

    The recrystallized H2SeO3 has to be dried in filter paper accurately wringing out the residual water.
    Keep the acid in a vacuum exsiccator over KOH during a three-four days time (NOT MORE, because distinct dehydration of the acid will take place).

    Your welcome!

  • Peng Bao asked a question:
    Ask for article

    Dear Xia

    I am now working on selenite effect on cancer, and i am very interesting in your paper:Mechanism of the anticancer action of selenium--influence on glycolysis and its key enzyme. 

    Would you please send me a PDF version?

    Many thanks!

    Sincerely Bao

  • Sfandiar Shikhzadeh added an answer:
    Can someone suggest the best technique to analyze Se in fish sample?
    AAS-GTA or AAS-VGA? How to improve the recovery value? Because I have low recovery? What is the modifier and if I use GTA, what is a good temperature profile?
    Sfandiar Shikhzadeh · Bushehr University of Medical Sciences

    Post-digestion UV irradiation proved very efficient since not only complete organoselenium decomposition was achieved but also the final step required for prereduction of Se(VI) into Se(IV) (i.e. heating at 90 °C for 30 min in 6 M HCl) could be avoided.

    http://www.sciencedirect.com/science/article/pii/S0003267007006976

  • Nicholas Kirkwood added an answer:
    Does anyone have a better method to synthesize good quality core shell cadmium selenium quantum dots?

    I use some reference to synthesis a good quality CdSe/ZnS gradient core shell quantum dots (emission wavelength 550 nm), but, I can't synthesis a good quality core shell QDs which emission at 450 nm or 650 nm (which means blue or red QDs).
    Can anyone give me some advice?

    Nicholas Kirkwood · University of Melbourne

    Highly emissive red quantum dots are relatively easy, a CdSe/CdS/ZnS core-shell-shell structure with ~4 monolayers of CdS and 1-2 monolayers of ZnS should give red emission and very high photoluminescence quantum yield. See the attached paper for a simple protocol - there is a spreadsheet in the SI to do the precursor requirement calculations. You can also make green emitting dots this way by reducing the number of CdS shells. 

    Blue emitting CdSe quantum dots are much harder to make, but you could try CdS/ZnS core-shell particles instead.

  • Margarete Maria Kalin added an answer:
    Does anyone need a fast growing high biomass selenium or nitrate hyperaccumulator for environmental cleanup?

    We have access to a Brassica species and a grass species that can be used for soil or water remediation.

    Margarete Maria Kalin · Boojum Reseach Limited

     this is an aquatic plant.. so it works on water not in soil - essentailly it puts the contaminat into the sediment.. where in most cases it gets biomineralized.. if you want a publication... let me know by e-mail margarete.kalin@utoronto.ca  have a nice sunday

  • Sultan Salah asked a question:
    Is the role of selenium in preventing hair falling out proven in evidence based medicine?
    There are various factors for hair falling and some studies suggest role of element selenium in preventing hair falling.
  • Shiv Prakash asked a question:
    How would a selenium web driver find the xpath of drag and drop among the choices?
    .
  • Runxiang Ni added an answer:
    What is the suitable method to assess available Se in soils measurement?
    I need it, please!
    Runxiang Ni · Chinese Academy of Sciences
    Tessier A,Campbell P G C,Bisson M. Sequential extraction procedure for the speciation of particulate trace metals [J].Analytical Chemistry,1979,51(7):844-850.

    An analytical procedure involving Sequential chemical extractions has been developed for the partitioning of Particulate trace metals (Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual.

    There were no discussions about Se.
  • Jiajun Liu added an answer:
    Does anyone know how selenium can change expression of genes? How do nutrients work in the cell?
    I need to understand how the nutrient work in the cell and relationship with changed expression of genes.
    Jiajun Liu · China University of Geosciences

    Thank you for your suggest

  • Moolchand Malhi asked a question:
    How to process (protocol) the blood serum sample for selenium determination?
    How to process (protocol) the blood serum sample for selenium determination?
  • Paula Aracena asked a question:
    What makes the difference between selenocysteine and cysteine residues in terms of enzymatic catalysis?
    This is almost a philosophical question, but I have always been mesmerized by the fact that a selenocysteine residue is a key residue for glutathione peroxidase catalysis. Are there studies comparing activities of Se-cysteine-containing and Cys-containing glutathione peroxidase? I am fairly ignorant in this matter, but I had to ask!
  • What conditions are best to reduce selenium powder by sulfurous acid? Should I dissolve the sulfurous acid in water or heat it until it melts?
    I am trying to synthesize CdSe quantum dots in aqueous solution and right now I am using hydrazine hydrate as reducing agent for selenium powder, but I want to try metol or sulfurous acid instead.
  • Jochen Vogl added an answer:
    How can I remove possible sulfur interference in HG-ICP-MS total selenium analysis of biological tissue?
    We have 90-92% recovery for total Se when analyzing biological CRM (fish or clam tissue). Recovery is ~100% for sediment CRM. We have tried different extraction methods and isotope dilution but always get the same result.
    Jochen Vogl · Bundesanstalt für Materialforschung und -prüfung
    mass spectrometric interfences ususally lead to an increased signal intensity and not to a decreased one. When you get the same result for different Se isotopes it is a hint that there is no problem with interferences. Also in hydride generation you have less interferences than in normal ICPMS.
    potentail sources of errors could be incomplete extraction/digestion or strong matrix effects. I would try to completely digest the samples e.g. by a microwave assisted acid digestion. Another potential sourec is that you do have different yield in the hydride generation process for biological samples. A complete digestion could help here also.
  • Nagarajan Srinivasan asked a question:
    Role of selenium with herbal drugs in cancer therapy?
    Is it effective?
  • Behnam Beigzadeh added an answer:
    role of polysacharide in selenium nanoparticle systhesis
    can anyone pls explain the role of polysacharide during systhesis of selenium nanoparticle.

    i need to specifically know if its use to stabllise the nanoparticles or does it contribute to the size reduction of the nanoparticles.
    Behnam Beigzadeh · University of Tabriz
    In fact as polysaccharide reducing the autogenous process selenium nanoparticles act , such as what can as phenolic compounds be done.
  • Majid Darroudi added an answer:
    Can anyone suggest how to reduce the size of biologically synthesized selenium nanoparticles?
    Currently I am getting nanoparticle size of 150-250 nm. I would like to reduce this size to less than 100 nm.
    Majid Darroudi · Mashhad University of Medical Sciences
    You can use of physical methods after Se fabrication for reducing the size such as UV-irradiation or pulsed laser (As N. Barsch's suggestion), ...
  • Bram Bekaert added an answer:
    Which form of selenoprotein exists in Se-enriched yeast?
    We know that no selenoprotein synthesis system has been discovered in yeast and higher plants. How do the Se-yeast produce selenoproteins? Are they only the selenium-containing proteins (I mean the selenium is in protein not in selenocysteine or SeMet), or do the proteins contain Secys residues? If the yeast lack the Sec(Secys) incorporation machinery, does that mean that the selenoprotein gene from mammals can't be expressed in Se-enriched yeast?
    Bram Bekaert · Universitair Ziekenhuis Leuven
    Selenium in selenium-enriched yeast produced using sodium selenite as a source is typically in
    the form of the seleno-amino acid selenomethionine, accounting for approximately 60-85% of
    total selenium species in the selenium-enriched yeast product. Selenocysteine is the second
    most abundant identified species, approximating to 2-4% of total selenium species. Inorganic
    selenium (IV) ion is normally found at less than 1% of total, confirming that virtually all of the
    selenium present in the product is organically bound. The remaining proportion is the sum of
    minor species.

    Reference: The EFSA Journal (2008) 766, 1-42

    Bram

About Selenium

An element with the atomic symbol Se, atomic number 34, and atomic weight 78.96. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE.

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