• Ashish Dutt added an answer:
    ** ** ** ** ** **?

    ** ** ** ** ** **?

    Ashish Dutt

    What you are looking for is called as "Scrapy" Its an open source python framework and it supports extracting DOM elements with XPATH. This blog post might be of help.

    + 1 more attachment

  • Mohamed Mehdi Kadri added an answer:
    Is there any lab' that can provide us with the levy and technical analysis of the radioactive element Iridium, selenium, indium and tellerium?

    I seek the levy and technical analysis of the radioactive element Iridium, selenium, indium and tellerium. and in what laboratory could us making this analysis.?

    Mohamed Mehdi Kadri

    Good Afternoon and Happy IDE 

    Dear colleague you can see with the academic Geology lab in Kazan,Russia Reason that there is a convention between us

    King Regards

  • Jackson Achankunju added an answer:
    What is the appropriate concentration to add sodium selenate as selenium source in the growth medium of spirulina and chlorella?

    I want to add sodium selenate to the growth medium of spirulina and chlorella to increase the nutritional values so i want to know safe concentrations  of sodium selenate and add it to the growth media.

    Jackson Achankunju

    Dear Abdelgawad,

    Sodium selenite concentrations below 400 mg l1 were found to stimulate algal growth, especially in the range of 0.5–40 mg/l.  500 mg/l or more of  Sodium selenite was reported  toxic to S. platensis and it resist higher selenite by reducing toxic Se(IV) to nonsoluble Se(0).

    Please find  a couple of papers in this regard.

    1. Bioeffects of selenite on the growth of Spirulina platensis and its biotransformation

    by Zhi-Yong Li,Si-Yuan Guo and Lin Li

    2. Production of Chlorella biomass enriched by selenium and its use in animal nutrition: a review by  Jiří Doucha , Karel Lívanský, Václav Kotrbáček and Vilém Zachleder

    Good luck!!

  • Muhammad Yasin added an answer:
    Is it possible for a Fe-S protein to have its sulfur (S) substituted by selenium (Se)?

    Considering that organic selenium (as seleno-methionine) is not metabolically differentiated from sulfur-methionine, is it possible that this substitution occurs also on Fe-S proteins at the Complex I and II of of mitochondrial electron transport?

    Muhammad Yasin


    I think so. I have been working with plant treated with Se. and what I found when certain plant species are treated with high concentration of Se the total concentration of S (in acid digested samples) is affected negatively in above ground plant parts and plants protein contents are also affected by supplementation with high Se content in soil. 

  • Mehrdad Mirouliaei added an answer:
    Is selenium supplementation indicated in hyperthyroidism?

    I read about the bebefits of selenium supplementation in autoimmune thyroid diseases and hypothyroidism. I am interested to know about the benefits of selenium supplementation for hyperthyroidism as well as its mechanism of action in these settings. Thank you for your feed back.

    Mehrdad Mirouliaei

    selenium substitution may improve inf amatory activity  in autoimmune thyroid disease but  we need many investigation that it is effective in other autoimmune endocrine disease

  • Lina Antenucci added an answer:
    Could someone help me with suggestions about crystallization of selenium-derivatives proteins?

    I am trying to crystallize a protein with and without selenium (selenomethionine). I obtained crystals with protein without selenium, but I am not able to crystallize the selenium derivatives. Do you have some suggestions about this? 

    Thanks all!

    Lina Antenucci

    Thank you very much for all these suggestions! I have no experience in how to improve crystallization :( 


  • C. García Núñez added an answer:
    How can I understand the behaviour of Selenium nanowires with UV photodetection?

    I tested the photodetection performance of Se nanowires. When I measure Current as a funtion of Time with a fixed bias I am observing that under UV light illumination the current increseas with respect to dark current. But while doing   I-V under the illumination of varying intensity of UV light the photocurrent decreased as compared to dark current. Could someone please help me to understand why is it so?

    C. García Núñez

    For me, it is not also clear the description of your experiment. I have a short experience with the characterization of single ZnO nanowire based photoconductors, and I would like to tell you some suggestions that you probably already know.

    1. You should measure first the dark current level of your nanowire. Remember that the nanowire has a nanometric cross-section, then the current density through a nanowire is extremely high even using low voltages. Therefore, you should not use extremely high voltages. In this regard, you can prevent nanowire heating and degradation overtime.

    2. Secondly, you could measure the rise and decay time of your nanowire by illuminating the nanowire with UV light.

    3. Finally, you can measure the light current under UV illumination.

    In my opinion, the only way possible to observe a dark current level higher than the light current in a photoconductor, is because of the dark current was not measured properly, i.e. it was measured after illumination when the "intrinsic" dark level has not been reached.


  • Samuel Toluwalope Ogunjo added an answer:
    Can anyone help me with the detailed procedure for green synthesis of selenium nanoparticles?

    please i would like to make enquiries on material science. green synthesis of selenium nanoparticles using aloe vera or moringa as reducing agents preferably under ambient conditions?

    Samuel Toluwalope Ogunjo

    If you have a selenium source, you can get in touch with Dr. Oluyamo S. S. (Department of Physics of FUTA), if you will like the top-down approach, there is locally built machine under his care.  Of course, there are other approaches but...

  • Muhammad Yasin added an answer:
    What methods are there to dissolve gray/black elemental Se(0) powder into water?

    I am currently conducting an embryo toxicity assay with fish models, and would like to (optimally) create a low concentration working solution of elemental Se(0). The selenium was ordered from Sigma-Aldrich and is in powder form. Any references to existing methods in literature would be much appreciated. 

    Muhammad Yasin

    Yes elemental Se insoluble in water and less toxic as compared to other chemical forms of Se. Sodium Selenate and and sodium selenite are water soluble, you can use these compounds to see Se toxicity .

  • Dan Beckwitt added an answer:
    What are the suitable management practices for removing the selenium content in tile drain water?

    Denitrifying woodchip bioreactors are commonly used practice, installed at edge of the agricultural field to remove the nitrate load in tile drain water. Our findings showed that bioreactors successfully remove Selenium content in tile drain water. Other than bioreactor, anyone involve in research in Selenium removal?

    Dan Beckwitt

    Building a bioreactor with saccharomyces cerevisiae may be a more practical option, depending on how concentrated the excess selenium is.

  • Marco Voltolini added an answer:
    Does anyone have a .cif file for hexagonal Selenium, space group P3121 (152)?

    crystallograpic information file for Selenium

    Marco Voltolini

    For future reference, I'd consider searching on the COD database. For Se xtl structures you can find several options here:


    In that search page just insert "Se" in the "1 to 8 elements" field and "1" and "1" in the boxes of the "number of distinct elements min and max" field and press the "send" button.

    You'll get a list of different polymorphs of Se, including the one you are looking for and you can download the .cif. You'll also have references and all.

    Another good part is that it's free. :)



  • Mathuri Selvarajan added an answer:
    Why is the colour of CdSe thin film is white in color?

    I have coated it at 300 and 350C and used Cadmium chloride and selenium dioxide as a source material. Normally the colour of the CdSe thin film will be red or reddish brown in colour. but what i got is white in colour i dont know why.

    Mathuri Selvarajan

    Hello sir  thanks for your immediate clarification. I have coated it on glass substrate by spray pyrolysis method and regarding roughness i didnt measured it yet. when i increase the concentration of the source material  then iam getting milky white other wise its shinny white colour sometimes its look  colourless.

  • Fazila Yousuf added an answer:
    How should I increase 2% nitric acid to 7% nitric acid to make a 20ppm Selenium standard from the 1000ppm stock in 2% nitric acid ?

    I got Selenium 1000 ppm standard in 2% nitric acid (perkin elmer). Now I want to make 20ppm Selenium standard from the 1000ppm stock?

    My stock solution is in 2% nitric acid. I want to prepare 100ml of 20ppm Selenium standard but the nitric acid concentration of the 20ppm standard should be 7%. Can anyone explain how I should increase 2% nitric acid to 7% nitric acid please.

    Fazila Yousuf

    Many thanks Martin Lenicek. I understood the point. I have concentrated (70%) Nitric acid in my lab from which I can prepare desired base acid solution for my standards. 

  • Muthuswamy Jaikumar added an answer:
    Is there data other than USEPA literature values LC50 for Selenium for marine species ?

    I have searched literature values for Selenium (Sodium selenate). I got USEPA literature 2004. I need other than USEPA: Australian, ASEAN and New Zealand water quality criteria for selenium lc50.

    Muthuswamy Jaikumar

    Dear Arif thank you for sending a link in that i seen same USEPA data. Like USEPA i need literature values neither like Australian, ASEAN and New Zealand water quality criteria for selenium lc50 for marine water species. 

    Thank you for sharing this information 

  • Danyel Bueno Dalto added an answer:
    Why is there a higher tissue deposition of Se when supplementing Cu?

    It was reported a higher tissue deposition of Se (compared to a control diet) when high levels of dietary copper were supplemented concomitantly with toxic levels of selenium. By using dietary levels of these to mineral, are the same results expected?

    Thank you very much

    Danyel Bueno Dalto

    Thank you very much for the reference.

  • Varsha Dilip- Jadhav (Rathod) added an answer:
    What is the best method for dissolving organic selenium in water (or the best solvent for it)?

    In fact, I want to dissolve organic selenium for preparation stock, then spray this stock on food and feeding goldfish with formulated diet.

    Varsha Dilip- Jadhav (Rathod)

    I have attached herewith one paper for your information.

  • Dan Beckwitt added an answer:
    What is the consequence of supplementing iodized salt for an endemic goiters population in the context of low iron and selenium status?

    School-aged children in a rural area where a new salt iodization program supplements iodine through USI; Studies in the area indicated children are also both iron  and selenium deficient. What is the biochemistry and the proper management issues and procedures towards prevention and control of such concurrent deficiencies.

    Dan Beckwitt

    Treat selenium deficiency before iodine deficiency, the reverse has been hypothesized to induce autoimmune thyroiditis.

    Here's a recent paper indicating more trace mineral deficiencies such as magnesium may also play a role in pathogenesis: http://press.endocrine.org/doi/full/10.1210/jcem.87.4.8421

  • Salah Mahrous added an answer:
    How to make CdSe quantum dots?

    Selenium metal is not soluble in trioctylphosphine and octacene. Please suggest proper procedure.

    Salah Mahrous

    use hot conc HNO2ml/g

  • Md. Zillur Rahman 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?
    Md. Zillur Rahman

    Sometimes it is not  easy to get better recovery so we can use microwave digestor to digest the fish sample.

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

    See above.

    Michael Nazarkovsky

    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!

  • 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

    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.

    • [Show abstract] [Hide abstract]
      ABSTRACT: A new approach for synthesis of high quality core/shell nanocrystals, “thermal-cycling coupled single precursor” (TC-SP), was developed. It was applied for the synthesis of high efficiency, good color purity, nearly monodisperse, alloying-free, and stable CdS/ZnS core/shell nanocrystals with their emission peak tunable between 375 and 475 nm. A comparison study on TC-SP versus the classic successive ionic layer adsorption and reaction (SILAR), both in one pot, revealed that, although the reaction temperature was significantly reduced and the procedure was simplified for TC-SP, the overall quality of the CdS/ZnS core/shell nanocrystals yielded by TC-SP was found to be superior. A quantitative chemical etching method was developed for determining the radial distribution of elements in bandgap/composition engineered nanocrystals.
      Chemistry of Materials 01/2010; 22(4). DOI:10.1021/cm902516f

    + 1 more attachment

  • 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

     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

  • Closed account 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
    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

    Thank you for your suggest

  • Claudio Davet Gutiérrez Lazos added an answer:
    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
    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.
  • 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
    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
    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), ...

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.

Topic followers (189) See all