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  • Sujoy Sarkar added an answer in Indium:
    Is indium sulfide an indirect bandgap material or direct bandgap material? or both?

    The bandgap reported for indium sulfide whether it is direct or indirect is still controversial. Anybody shed some light upon it?

    Sujoy Sarkar

    You can go through this article where they have concluded from experimentally and theoretically that In2S3 is an indirect band gap material (band gap 2.01 eV) .

    Thin Solid Films, Volume 517, Issue 7, 2 February 2009, Pages 2316–2319

    "Bandgap properties of the indium sulfide thin-films grown by co-evaporation"

  • Louis Brassard added an answer in Cognitive Systems:
    Is Chalmers' so-called "hard problem" in consciousness real?

    In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

    “Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

    Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

    Personally, I agree with Stanislas Dehaene's opinion.

    Louis Brassard


    What is a music composer doing?  Is the music composer consciously composing music? And when you listen to music and that you are emotionally moved by it then all kind of emotion rise into your consciousness.  Understanding what is musis is central to understanding consciousness.  All vertebrate nervous system developed primarily to move bodies and music is the art that this movement.

  • Marlonni Araujo added an answer in Callus Culture:
    I was using 9uM of BAP and 4,5uM of ANA in my C. papaya callus culture, but they still growing like a callus and not proliferate shoots, why?

    someone can help-me?

    They are in this conditions:

    16/8h photoperiod

    0,5% phytagel

    sucrose  6%

    1x MS vitamins

    MS fullstrength

    Marlonni Araujo


  • Jeffrey McCormack added an answer in World War II:
    Does anyone know any publications that deal with the local residents experiences of the Holocaust?

    Looking to see how the social life of the local residents near camps such as Auschwitz were impacted by the activities of the extermination camps. 

    Jeffrey McCormack

    The universal ignorance feigned by the post war German populace will make this a challenging research topic.  I'll see what i can find this weekend.

    + 2 more attachments

  • Samy Yousef added an answer in Elastic Modulus:
    How do I calculate flexural (3 point bending) strenght and modulus?

    how to calculate Flexural Strength and Modulus? I meant 3 point bending

    i have done 3 point bending on a composite.....

    i have my own data here in excel form....

    please some body help me and tell me....

    the data are force (N) vs extension (mm)

    what does extension mean in 3-point bending test?does it mean deflection?

    how can i convert this force vs extension to stress vs strain?

    how can i calculate flexural modulus and flexural strenght and flexural strain?

    thanks all

    in the attachment you can find the excel file...

    Samy Yousef

    You can find all equations in the attached photo or in the following reference. Also, you can used the attached Excel sheet as a guide for you.

    Good Luck

    1. J. S. Fitton, E. H. Davies, J. A. Howlett & G. J. Pearson,”The Physical Properties of a Polyacetal Denture Resin”. Clinical Materials 17 (1994) 125-129

    + 1 more attachment

  • Yogesh Patel added an answer in Herbs:
    Can anyone identify this herb ?

    ottawa, Canada

    Yogesh Patel

    thanks Jeff Ollerton 

  • Sujoy Sarkar added an answer in Sonication:
    Why are nitrogen-doped rGO sheets hard to disperse into NMP?

    Compared with rGO, the nitrogen-doped rGO became very hard to be dispersed into NMP by probe sonication; For example, after 20 min sonication, the rGO can be well dispersed into NMP, while it takes >4hr sonication to disperse most of the N-rGO in NMP.

    PS. I use ammonia solution as precursor and hydrothermal route to prepare the N-rGO.

    Sujoy Sarkar

    I think the simple reason behind this problem is the electrostatic repulsion between a lone pair of N (nitrogen) present both in N-rGO and NMP. Therefore, sonication takes less time to disperse in NMP in case of rGO  where no N is present.

  • Han Ping Fung added an answer in Hypothesis Testing:
    Should hypotheses always be based on a theory? Can someone refer me to a research paper that emphasizes the need for theory driven hypotheses?

    Should hypotheses always be based on a theory? I will provide an example here without variable names. I am reading a paper where the authors argue that X (an action) should be related to Y (an emotion). In order to support this argument the authors suggest that when individuals engage in X, they are more likely to feel a sense of absorption and thus they should experience Y. There is no theory here to support the relationship between X and Y. They are also not proposing absorption as the mediator. They are just using this variable to explain why X should lead to Y. Would this argument be stronger if I used a theory to support the relationship between X and Y? Can someone refer me to a research paper that emphasizes the need for theory driven hypotheses? Thanks!

    Han Ping Fung

    Hi Geng,

    In the absence of precedent theory, a new / reformed theory will be formed after your current research model / conceptual framework (including its hypotheses) being empirically tested and showing evidence to support your new / reformed theory.



  • M. Farooq Wahab added an answer in Column Chromatography:
    How do I pack a column with sephadex LH 20?

    I am going to use Sephadex LH 20 (from GE) with chloroform as the solvent for separation of my compounds. Can I use pure (100%) chloroform for packing the column? I am asking it, because in GE's manual they have written of using chloroform with 1% ethanol as the solvent for packing the column? Can anyone help me whether pure chloroform is not recommended for it?

    M. Farooq Wahab

    According this manual, sphadex LH 20 would float in chloroform. On page 4, there is a list of alternative solvents for packing this media. As Jack said chloroform already has ethanol, so it might not matter.


  • Shariful Islam asked a question in Environmental Microbiology:
    Any explanation on how to differentiate proximities of the following?

    Bray-Curtis Dissimilarity, Pearson dissimilarity and Sorensen-Dice similarity, Please in details...

  • David Dunaetz added an answer in Impression Management:
    Can anyone help us research self-handicapping in business?

    Self-handicapping, impression management, goal orientation

    David Dunaetz

    A Google Scholar search on "self-handicapping" and "organizations" will provide you with many articles that have examined these issues:


  • Sujoy Sarkar added an answer in Zeta Potential:
    Why does zeta potential of a surface varies with flow velocity of adjoining electrolyte solution ?

    Why zeta potential of a surface varies with the flow velocity of adjoining electrolyte solution?

    Sujoy Sarkar

    The answer is hidden in the definition of the Zeta potential which is  the potential difference between the dispersion medium and the stationary layer of fluid attached to the dispersed particle and the magnitude of the Zeta potential indicates the degree of electrostatic repulsion between adjacent, similarly charged particles in a dispersion.

    So when flow velocity of the adjoining solution changes, it affects the electrostatic repulsion and reflecting in the Zeta potential.

  • Bassem Nabawy added an answer in Total Porosity:
    How do I estimate the porosity of fractured basement rocks?

    - Measuring porosity from the core Samples.

    - Estimating porosity form the satellite image analyses.

    - Estimating porosity form the field studies by measuring the fractures dimensions.

    Bassem Nabawy

    That is right, but If I'd like to conduct preliminary surface studies, so how to estimate porosity from images and photos as well as from the core plugs in the Lab. as a routine core analyses

  • Aristide Foudji added an answer in Wind Power and Power Systems:
    How to calculate the over estimation and under estimation cost of wind power in solving opf ?

    any paper on model calculation

    Aristide Foudji

    Hope the link below could help.


  • Raid Amin added an answer in Advanced Statistical Analysis:
    Can anyone explain to me the balanced incomplete block design?

    My PhD research consist in evaluate 9 strategies or paths of doing ads. I'm using a Likert Scale to know which one is more creative, which strategy boost purchase intention and which one generate more positive attitude towards the ad and attitude towards the brand.

    My universe is 726,696 subjects and my sample 384 (error 5%-confidence 95%). By resources I can't do this 384 subjects x 9 strategies = 3456 persons.

    I need to find a sample size where at least every person should evaluate 3 ads at the same time. And each of the 9 strategies should be evaluated the same number of times.

    They recommend me to use "balanced incomplete block design". Any insight is welcome. Thanks.

    Raid Amin

    It is Balanced because the loss of information is equally spread across the blocks.

  • Aristide Foudji added an answer in Simulink:
    How can I calculate the heat losses in the stator windings of SCIG (squirrel cage induction generator)?

    and how can i make a simulink model to calculate them?

    Aristide Foudji

    You can use Ohm's law. However, you must measure the resistance of the stator windings per phase with an ohmmeter. You also need to measure the current on a choosen line. Check the link below on page 5.


  • James Noar added an answer in Veterans:
    Disabled veterans are being overlooked for scholarships and degrees in graduate counseling studies?

    In my research for mental health counseling, I have found scholarships and grants for women, women of color(I use this term for anyone not 'white' as cases describe), men of color, disfranchised individuals, research, data processing, and for training associate's. It appears that scholarships and grants from male disabled veteran's to pursue graduate degree's do not exist. Can anyone offer proof to counter this?

    James Noar

    Dear Beatrice,
    If I get SPAM from this, I may well report you to the site for SPAMMING. As a professor, you should know better than to post SPAM links here. That is completely inappropriate.

  • Farooq Ali Khan added an answer in Literary Theory:
    Can anyone recommend introductory material on literary theory and analysis of literary texts? It would be better if it covers various approaches.

    I need it for teaching at undergraduate level for learners. Your effort will highly be appreciated.

    Farooq Ali Khan

    Thanks everyone. I am actually looking for reference material which not only covers theory but also practice.

  • Afaf Mohammed asked a question in GPx:
    What are the simplified assay methods of SOD,CAT,GSH,GPX?

    I am searching for  simplified assay methods for estimation these antioxidants in fish liver tisse homogenate.

  • Michael Stoelzle added an answer in Evapotranspiration:
    How to calculate mass balance in aquifers?

    For my PhD study, as part of my objectives is to calculate the mass balance (evapotranspiration and evaporation) in an aquifer. For this i would like to get journals of how to estimate both parameters. 

  • Viktor Y Butnev added an answer in HEPES:
    How to store my protein?


          I usually store my membrane protein in 20 mM Hepes, pH 7.4, 300 mM NaCl, 5% glycerol at 4 degree. After 2 or 3 weeks I saw precipitation at the bottom. I removed the precipitate and found that my protein concentration drops. So how should I store my protein better? There may be the problem of protease. Can I store with higher concentration of glycerol at -20 degree? I am worried that if I store at -80 degree, and then thaw, the protein will be denatured. thanks.

    Viktor Y Butnev

    It depends on each particular protein and usually membrane proteins are more prone to aggregation because of their high hydrophobic properties. There is no universal protocol for buffers to store membrane proteins for a long storage. But there are some general rules you might want to consider:

    1) All the buffers should have pH close to physiological pH like your buffer.

    2) I would recommend to keep NaCl concentration around physiological ~ 150 mM

    3) It would be better to increase the concentration of glycerol up to 50% (need to be determined in experiment)

    4) It would be good to include a protease inhibitor cocktail in your buffer.

    5) You are right in your suggestion to keep your membrane protein frozen at - 20°C.

    6) I would recommend to have in your buffer the same detergent that you used for extraction of your membrane protein from the cells (the concentration should be determined in experiment).

  • Thierry De Mees added an answer in Gravitation:
    In GR, can we always choose the local speed of light to be everywhere smaller that the coordinate speed of light? Can this be used in a theory?

    It seems that many, if not all, solutions of Einstein's equations, such as black holes and grav. waves, can be given coordinates x\mu in such a way that the local speed of light is always slower than the coordinate speed of light. Think of gravitational lensing: the index of refraction of a gravitational potential always seems to be >1, in practical examples, so a gravitational potential slows light down, and never speeds it up (if coordinates are chosen carefully). This wouldn't be true for a negative-mass Schwarzschild solution, but that seems to be outlawed in nature.

     Now this was only a conjecture, I have not attempted to prove it. How would a rigorous mathematical theorem be formulated? And did anybody - and here I mean a wise person, not the average blogger - ever try to do something interesting with this observation? Like constructing a “hidden medium” for curved space-time?

    Thierry De Mees

    @Mohamed El Naschie: this remark is totally  logical in terms of degrees of freedom. It also is a typical Hawking way of thinking. However, I am shocked about the ease with which nowadays' scientists add dimensions to theories, add new theories to explain failing theories while maintaining them, and so on.

  • Vini Gautam added an answer in Glutamine:
    What are the reasons for dead cells in primary hippocampal culture?

    I have been trying to grow primary culture from isolated hippocampi from rat pups. Sometimes the cells survive while most other times they strangely land up dead like debris after 3-4 days. I have tried changing different things but cant get to a consistent healthy culture. Can someone please help? I am quite frustrated! Below are the details:

    The age of the pups is usually between 0-2 days. I dissect the hippocampus out and dissociate it in papain based solution. I then gently triturate the tissue pieces in pre-warm culture medium (no centrifuge), count the cells in Haemocytometer, and then plate them at 20*10^4 /ml onto glass coverslips kept in a 24-well plate. The coverslips are coated with poly-L-lysine (MW>150kDa) mixed with or without collagen.

    Now, most of the times I can see healthy cells (e.g. neurons with long processes) when I count them in haemocytometer. So I presume there is nothing wrong with my trituration. But after plating, the cells dont grow - next day they dont have processes anymore, the glia doesnt grow, basically nothing happens. I guess they dont die either (because they appear phase bright at least for next 2 days). But then after 3 days, they start to die, and after 4-5 days, its just debris left over in the wells.

    Is it the coating? I clean the coverslips with acid, wash them and coat PLL or PLL/Collagen as per the instructions. I tried ornithin/Laminin too, but no improvement..

    Is it the medium? I tried DMEM with FBS, B27, glutamine as well as Neurobasal-A with FBS, B27, glutamine. The medium pH after preparing is usually 7.4-7.6 and the osmolarities range between 280-310.

    Please help!!! I cant think of anything more! Thank you very much.

    Vini Gautam

    Thanks, everyone. I will try ornithine. What should be the MW of it, does it matter? I am not using heat inactivated FBS, will do that. Anyone has experience with Neurobasal-A medium? Or can you share your thoughts on the medium composition? Eg. Should you add FBS and B27 together or just B27 itself is enough?

    Also, just using P0 rats because I did that for mice and dont have experience with prenatal :-(

  • Sujoy Sarkar added an answer in Nanodiamonds:
    What are the absorption coefficient and refractive index of Nanodiamond?

    how to prepare solution for DLS of nanodiamond?

    Sujoy Sarkar

    Dear Mohib, you could follow this article, you might get your answer.

    Nature Nanotechnology 7, 11–23 (2012)

  • Ian Miller asked a question in Freeze Drying:
    Why does my protein look like glass fibers?

    We are extracting type 1 collagen through a base, HCl, salt precipitation, and freeze drying method and have noticed that the extracted protein looks like glass. Well at least glossy, and the fibers are not compact. We have tried concentrating our gels before lyophilizing, different freezing temperatures, using acetic acid instead of HCl, and pressing the collagen at up to 8 tons. Our SDS-PAGE shows that the same banding patterns appear (alpha [1,2], beta, and gamma bands) as Sigma-Aldrich rat tail derived type 1 collagen, but our bands are all slightly shifted up 5-10 KDa. What is causing this glassy looking collagen fiber formation. Thank you for viewing and any input is appreciated!

  • Fernando Feliciano Lopez-Calderon added an answer in Immunofluorescence Staining:
    Immunofluorescence staining protocol: can I leave fixed cells in antibody solution for 4 days at fridge?

    I'm running Immunofluorescence imaging today, and I added the antibody. Cells are i at 37 incubator for four hours. I wont be able to finish imaging today due to the number of samples. Can I leave my cells for four days at fridge in the diluted antibody to continue imaging later? If I remove the antibody and add PBS, can I detect any signal after four days?


    Fernando Feliciano Lopez-Calderon

    Do not let the cells incubate with the primary antibody for so long. The longer it takes, the more background you get. Its better to leave them in PBS solution.

  • Faris Alshubiri added an answer in Experimental Economics:
    Are there any surveys in Financial Experiments?
    I am trying to find new surveys in Financial Experiments. Is someone aware of any surveys in this area? Whichever references would be much appreciated!
    Thanks in advance.

    Kind Regards,
    Faris Alshubiri

    Dear Konstantina Mari 

    See the attached file in 2015 , may be help you 

  • John J Orczyk added an answer in Microglia:
    When there is injury or degeneration in the brain, do microglia prefer to migrate or proliferate in the focal area?

    Thanks in advance!

    John J Orczyk

     It depends on the specific brain region and type of injury.  for example:

    After entorhinal cortex lesion, the chemokine CXCL10 is highly expressed in the dentate gyrus as microglial migrate from adjacent hippocampal subfields. The receptor for CXC10 is the microglial surface recefor CXCR3. Lesioning the entorhinal cortex of CXCR3 KO mice does not lead to disappearance of affected dendrites as it does in WT mice. In contrast, the microglial response to facial nerve axotomy is characterized by proliferation rather than migration. CXCR3 KO mice show no differences with WT mice in dendritic disappearance 8 d after axotomy. The implication is that in the absence of CXCR3, microglia can proliferate, but not migrate (Rappert et al., 2004).

    Rappert, A., Bechmann, I., Pivneva, T., Mahlo, J., Biber, K., Nolte, C., ... & Kettenmann, H. (2004). CXCR3-dependent microglial recruitment is essential for dendrite loss after brain lesion. The Journal of neuroscience, 24(39), 8500-8509.

  • Sergio Dominguez Lara added an answer in Confirmatory Factor Analysis:
    Factorial analysis in a questionnaire based in a theory of personality: procrustean rotation or a confirmatory factor analysis?

    If i want to perform a factorial analysis in a questionnaire based in a theory of personality, which has constructs very close conceptually and empirically, the best choice is a procrustean rotation or a confirmatory factor analysis.

    Sergio Dominguez Lara

    Excellent! Thank you.

  • Adam B Shapiro added an answer in Protein Purification:
    Does anyone have experience with Sephadex G-100 or G-200 swelling and column packing the column for protein purification with ÄKTA/FPLC machine?

    I am plan perform Gel filtration using sephadex G-100.  After swelling the gel for 72h, I tried to pack the column for gel filtration but the gels drains out with the buffer. The column was secured well with a filter at the lower end. I tried several columns but experience the same problem.

    Adam B Shapiro

    Actually, the manufacturer recommends swelling Sephadex G-100 for 3 days at room temperature. Shorter swelling time can be done in a hot water bath. You should include a preservative such as sodium azide to discourage growth of bacteria.

    Sephadex is not the best choice for FPLC because it can not handle much pressure. Try using Superdex or Superose instead.