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  • Daniel Lundberg added an answer in Solid-State Chemistry:
    What is the hydrate number(x) of ZrO(NO3)2-xH2O?

    I don't know accurate hydrate number of ZrO(NO3)2-xH2O

    Some  hydrate number of ZrO(NO3)2-xH2O is 2, ohter is x such as sigma aldrich ..

    what is accurate hydrate number? and what do you think about it?

    Daniel Lundberg · Swedish University of Agricultural Sciences

    Hi, Seunghoon!

    This question has been answered on ResearchGate before (see link or use a search engine). As with most variable hydrates, x can change depending on how the salt is stored (among other things). One way of measuring this is to use thermogravimetric analysis on your sample, just as Thibaud suggests in the link below.



  • Pooja Khurana asked a question in Cell Cycle Analysis:
    Best marker to differentiate between MEFs and mESCs?

    Hi, which antibody/marker acts best to distinguish between MEFs and mESCs in flow cytometry when using Annexin V-PI for Apoptotic and also for PI only cell cycle analysis?

    Considering that Annexin V is a surface marker, whereas for PI only- in cell cycle- the cells are fixed with 70% ethanol overnight.

    Many thanks,


  • Andreas Luedeke added an answer in Causality:
    Is a concept of causality required in science?

    John D. Norton characterized "Causation as Folk Science",

    (see http://quod.lib.umich.edu/p/phimp/3521354.0003.004/1).

    Would you say that causality is a well-defined concept that is

    essentially required in science?

    Andreas Luedeke · Paul Scherrer Institut

    First to Edwin: I think the transition from Newton's mechanic to Einstein's relativity was not just replacing bricks in a building. Of course Newton's mechanic is still very useful, but it is much more limited in the required border conditions than it was ever anticipated. And that is the way science will develop; in 1000 years people will judge today's laws of physics not as wrong, just as rather limited in it's border conditions (e.g. for practical applications in the 3rd millennium, like interstellar travel ;-)

    But replacing the concept of causality is far beyond replacing some laws of physics.

    To Christian: of course we get better and better in making predictions. But what is even more astonishing is that we get more and more aware of principle limitations of predictions. Chaos theory predicts that quantum effects can influence a macroscopic phenomenon like the weather. That does not mean that we don't have room to improve our predictions, but it is clearly the end of the philosophical idea of determinism. The world is not pre-determined. God does throw dice ;-)

    I think we have a different idea what causality means. In my opinion it does not mean, that we know how A leads to B. It means that any event B is caused by some event A. It is not necessarily a 1:1 relation: A may can have other outcomes than B or B can be caused by C as well. But whatever happens has been triggered by former events. Not by events coming later in time, and something must have been there to cause it. The only alternative concept I know of is God: he can create and destroy without being triggered by anything. Of course: if the universe is just a 3D film with 24 universes created and destroyed per attosecond, then we would just perceive the illusion of causality. The only connection between the raindrop falling on my head and the head being wet the next second is in my perception (or in the intention of the maker of the film). The obvious problem with this concept is, that all science would be futile. In this film you could only make predictions under the assumption that the director sticks to his own rules.

    Fact is: we are not able to tell the difference. Any law in physics could change any minute; nobody can know that. You might believe in the laws of physics; but you might as well believe in voodoo: whatever works for you!

    If you accept the fact, that we cannot know anything, then you are crazy :-)

    My point: science is not about truth at all. It is only about finding useful models.

  • Thomas N Kakuda added an answer in Clinical Pharmacology:
    What would be the preferable method to administer oral dosage form to patients having swallowing difficulties?

    Depending on the Tab or Cap, and the type of medicine, modifying these dosage forms can lead to reduced effectiveness of the medication, and increased risk of adverse effects. especially in hospitalized patients. Any alternative method then?

    Thomas N Kakuda · Janssen Research & Development, LLC

    Use the pop-bottle method for swallowing tablets and the lean-forward technique for capsules (Ann Fam Med 2014;12:550-552)

  • Swati Khare asked a question in Propulsion:
    What is the meaning of the 'tau propulsion factor' that Digigait's output gives?

    The Digigait gives us a number of paramaters to assess - one being the tau propulsion factor. It has no unit, is only for the hind paws of the mouse and is said to be a real #. What is the definition of this factor?

  • Renata Minullina added an answer in Marine Bacteria:
    How do I calculate the bacterial cell concentration if I cannot plate them directly on the solid media?

    Recently I've started working with new for me culture of marine bacteria Alcanivorax borkumensis. It is a hydrocarbon degrading bacteria. As a carbon source I use C16 (hexadecane) and it forms oil droplets on the surface of the media. It complicates CFU enumeration because I believe that  cells get pulled together by oil on the surface after spreading them on the plate. Do you have any suggestions how to overcome this problem?  

    Renata Minullina · Louisiana Tech University

    Dear Ana, if i understand you correctly you suggest to to stain dilution of cells with DAPI and count their number under the microscope (similar to hemocytometer method) and then measure OD600 of the same suspension?

  • Ankur Sharma added an answer in Social Influence:
    What are the personal and social factors that lead people to (a) start following good oral health practices (b) stop following bad ones?

    Many factors influence a person's decision to adopt a positive habit or stop a negative one. What are the personal factors and social factors that influence this decision for a dental patient? These habits may include positive habits such as using correct oral hygiene aids, using them correctly and in correct frequency of use. It may also include stopping improper dietary habits or reducing frequency and time of a 'bad' dietary component eg sugar. What are the personal and social influences that affect adoption of these practices? Please support with evidence.

    Ankur Sharma · Manav Rachna International University

    That's true! Even though the patients do not visit the dentist very often, dentist is still the primary source of knowledge and initiation of behaviour change. However, a dentist's time with the is being increasingly constricted. The challenge is to provide all that the patient may need for changing his behaviour. I feel use of social media apps and text messaging from dental practice to reinforce healthy behaviours may compensate this to certain extent, though not fully.

  • Steven Reiss added an answer in Motivational Psychology:
    Are there experiments on how motivation crowding or over-justification affects third parties?

    I.e. if we vary person X's payment for a task, does that affect person Y's motivation, even without varying Y's level of payment? 

    Many papers look at how payment can vary X's own intrinsic motivation, see e.g. Frey and Jegen 2001, Lepper and Greene 1973.

    Steven Reiss · The Ohio State University

    download "myths of intrinsic motivation" from my postings

  • Turbasu Sengupta asked a question in Cluster Chemistry:
    Why does ground state transition metal clusters shows high spins when other clusters are not?

    In atomic cluster chemistry,most of the s and p block clusters follows the rule of minimum spin.i.e. most clusters like Al,Na and noble metals has spin multiplicity (2S+1) either 1 or 2 (singlet and doublet) depending on total number of electrons either even or odd.However same rule does not hold for transition metal clusters.Most of the d block element shows high spin S=4,5,7 etc. Can anyone explain the reason. I've doubt that may be splitting of d orbital is the reason. However,I'm not finding and clear cut answer anywhere.Also if there is a crystal field splitting,is there any way to find out the d orbital splitting by any quantum mechanical calculation?

  • Daniela Vandepeer added an answer in Sustainable Development Education:
    Is there a comprehensive theoretical framework available for understanding the phenomenon of sustainable development in education?

    Development seen as ongoing process following from, say - introduction of a policy, approach or program or even broader than that.

    Daniela Vandepeer · University of Cambridge

    Thank you, Robert.


  • Mohd Fizam Zainon added an answer in Metal Casting:
    How can I prevent Mg2si particle burning during mixing with Al in stir casting?

    I found that Mg2si particle (reinforcement) was suddenly burning at Al (matrix) molten surface during mixing in stir casting process. After burning, all Mg2si particles turn into hard lumps like sludge. Therefore, it can't wetting between the particle and Al molten.

    Need suggestion how to prevent Mg2si particle burning during mixing?

    The reinforcement particle was preheated 200°C for 2 hours and melting temperature of the Al is 900°C. The reinforcement just 5%wt.

    Mohd Fizam Zainon · Universiti Malaysia Perlis

    Dear Mr Hassanzadeh

    Thank you for sharing.

  • Chuan Xia added an answer in Supercapacitors:
    How can I determine the redox potential by using cyclic voltammetry?

    The electrochemical behavior of manganese dioxide based supercapacitor electrocdes was studied by cyclic voltammetry.The peak is not always appear in figure of cyclic voltammetry.How to determine the redox potential ?

    Chuan Xia · King Abdullah University of Science and Technology

    If you can not observe the obvious redox peaks in MnO2 based supercaps electrodes, it's very normal. I guess you used the K2SO4 or Na2SO4 solution as electrolyte. From 0-1V in a CV pattern, the MnO2 will undergo a series of reversible successive surface redox reactions according to the following equation:

    MnO2+ xC+ + yH+ + (x+y)e ↔ MnOOCxHy (C=K+ or Na+

    The series of successive multiple surface reactions lead to a CV pattern whose shape is very close to that of the EDLC. 

    For more details, please go through the reference: Nature Materials 7(11): 845-854. 

  • Fatima Mohammed Hussen asked a question in Composition:
    What is the composition of energy drinks?

    Energy drink side effects

  • Shunzong Yuan added an answer in Histiocytes:
    Does anyone have experience or know if MUM1/IRF4 can be expressed in non-lymphoid cells?

    Like myeloid, dendritic, histiocytic, for example in AML.

    Shunzong Yuan · 307 Hospital of the Chinese People's Liberation Army

    Please see here:


    IRF4 can be expressed in adipocytes.

  • FC Prinsloo added an answer in Smartphone:
    Does anyone know a reliable source for the smartphone usage growth in Middle East?

    I am interested specially to accurate  statistics.

    FC Prinsloo · University of South Africa

    Dear Marziyeh

    I have seen a document on the mobile economy in Arab States 


    Pretty good reference as it was compiled for the World Bank I thing.



  • Eugene F Kislyakov 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.

    Eugene F Kislyakov · Belarusian State University

    Interaction of ideas with experience is a mystery, Arnold. Evidently, they differ.

  • Gary R McDowell added an answer in Dipole Moments:
    Where can I find the density values of merocyanine 540 (MC540) and 3,3'-diethylthidicarbocyanine iodide (DTDCI)?

    I am trying to calculate the ground and excited state dipole moments of these solvatochromic dyes, but in order to do so, I need to know the density of them in order to calculate Onsager's cavity radius.

    Gary R McDowell · Glasgow Caledonian University

    Thank you for your answer Professor Sarkar. I was able to estimate the density using molecular modelling and subsequently calculated the dipole moments of MC540 and DTDCI. My results were consistent with the works of others. Thanks again.



  • M. K. Olsen added an answer in Pure Mathematics:
    The concept of variation of the mass versus the velocity (m =m0/sqrt(1-(V^2/c^2)) is it a pure mathematical concept? or is it a physical reality?

    theory of restreint relativity

    M. K. Olsen · University of Queensland 

    It's a physical reality. It can be measured with charged particles at relativistic velocities in magnetic fields. It would also be taken into account in the design of particle accelerators. This url describes a beautiful experiment where it was measured:

  • Faustino R Perez-Lopez added an answer in Vitamin D:
    Who knows the difference between 25-hydroxyvitamin D and 25-Hydroxycholecalciferol?

    Could 25-Hydroxycholecalciferol be used as 25(oh)d?

    Faustino R Perez-Lopez · University of Zaragoza


    In addition to the previous comment, 25(OH)D is the main blood metabolite to study vitamin D status and has 2-3 week half life. On the contrary the bioactive hormone is 1,25(OH)2D acting both at the receptor level and by non-genomic mechanisms; its half life is 4-15 hours.


  • Omkar Pokharkar added an answer in Dissection:
    Is anyone aware of a method to snap freeze organs straight after dissection and still get a decent viable cell number after thawing?

    Thanks in advance for your replies.

    Omkar Pokharkar · D.Y. Patil university

    The main goal of freezing any organ quickly is to reduce the metabolic demand which is achieved when the temperature of the tissue or the organ falls rapidly and ATP utilization decreases. Flash freezing method can be used which involves submerging the organ or sample in liquid nitrogen and advantage of this process is that it does not need cryoprotectants as the rapid freezing inhibits the formation of ice crystals and the organ or the tissue are not damaged. The processs of freezing and preserving depends on the types of organs.

  • Yitbarek Takele asked a question in Variability:
    What is the propoer multivariate analysis to capture moderating variable, mediating variable and more that one outcome variable?

    The question is basically methodological, not conceptual. My proposed study plans the use of multivariate analysis that includes different antecedent variables, moderating variable, mediating variable and three outcome variables. My specific question related to this is suggestion for right method of analysis, software to be used and a model to be adapted. Thank you for your help.

  • John D. Watkins added an answer in Cyclic Voltammetry:
    Is that the oxidation and reduction peak depend on the voltage difference you run in cyclic volatametry?

    For example can we have same oxidation and reduction peak when you chop the Full CV diagram to shorter voltage difference around that peaks?

    John D. Watkins · National Energy Technology Laboratory

     The short answer to your question is that for a reversible system the window of observation should not affect the peak to peak separation and peak ratio. However, you should always make sure the window you use is large enough to capture the whole story.

    This is only part of the story and things very rarely behave as ideally as we would like. I suggest you read "Understanding Voltammetry" by Richard Compton, Chapter 4 deals in detail with your question and more, but all of it is good. Also consider "Electrochemical Methods" by Bard and Faulkner. You should buy them if you want to study more electrochemistry but the chapter I suggested is available on Google Books for free just as a quick read. Hope this helps.

  • Daniel Albrecht added an answer in Clinical Imaging:
    PET ligands for inflammation - which one is best ?

    18F-FDG is the most commonly used PET tracer for imaging inflammation, but it is hampered by non-specificity, as it is also taken up by cancer cells and to a variable degree in various physiological circumstances.

    1. Are there PET tracers, which accumulate more avidly in immune cells (ie. inflammation) than FDG, and thereby display higher SUV values?

    2. Are there PET tracers with a higher degree of specificity for immune cells than FDG, but which still displays sufficiently high accumulation in immune cells to allow clinical imaging?

    Daniel Albrecht · Massachusetts General Hospital

    There are several next generation ligands for TPSO that display much higher specificity for TPSO than PK11195, such as 11C-PBR-28, 11C-DPA-714, and 18F-FEPPA. While these are more inflammation-specific than FDG, the exact role of TSPO in inflammation is still pretty uncertain. There are a number of tracers in development for additional inflammatory targets like COX-1/2 and CX3CR1 (fractalkine receptor), but as far as I know these aren't yet available for human use. 

  • Juan Moles added an answer in Marine Ecology:
    Can anybody help me to identify this species?

    This species is found in the intertidal zones of Gujarat coastline of India. 

    Juan Moles · University of Barcelona

    This is a pelagic Thaliacean of the genus Salpa. The white string inside the animal is a stolon plenty of developing Salpas. The orange 'nucelus' is the stomach + the intestine of the animal.

  • Hema Latha added an answer in Protein-Ligand Interactions:
    Can someone help with 3 dimensional fluorescence spectroscopy?

    I need some explanation regarding the interpretation of 3 d fluorescence spectra of protein-ligand interactions.  What is meant by rayleigh scattering peak and second order peak.   Different articles give different explanations.  What type of information can be obtained from contour peaks.. 

    Hema Latha · VIT University

    I need one more clarification.  In some proteins i am getting the Rayleigh peak and raman peak.  But in some cases i am not getting those peaks.  Is it compulsary to have both the peaks in 3d fluorescence spectra.  Help me in finding out this. 

  • Sobia Ejaz asked a question in Azocasein:
    Protocol for azocasein zymography?

    I have to perform azocasein zymography for plant protein but I need a perfect protocol to do it. Can anyone provide me its protocol? Thankyou.

  • Tyler G Demarest added an answer in Glutathione:
    Does anybody have any information regarding the Glutathione - Sulphurdioxide interaction?

    Dear all. please let me know if you have any information regarding the Glutathione (the primary antioxidant inside human body), how it behaves with the different pollutants present in the environment?

    Tyler G Demarest · University of Maryland, Baltimore

    There are several reports in both wine production and in plant defense systems (http://www.ncbi.nlm.nih.gov/pubmed/25450923) demonstrating glutathione (GSH) detoxification of SO2 as well as increased oxidative stress in humans chronically exposed to motor vehicle exhaust (http://www.ncbi.nlm.nih.gov/pubmed/23738842).Hope this helps.



  • Hossein Javadi added an answer in Electromagnetic Fields:
    Are electromagnetic fields made up of virtual photons? Or are they merely a mathematical bookkeeping device for QED?

    QED rests on the idea that charged particles (e.g., electrons and positrons) interact by emitting and absorbing photons, the particles that transmit electromagnetic forces. These photons are “virtual”; that is, they cannot be seen or detected in any way because their existence violates the conservation of energy and momentum. Is there a way to explain virtual photon without using the uncertainly principle?

    Hossein Javadi · Islamic Azad University

     Dear Frank
    Thank you for your suggestion. I have read your interesting article. You have propounded a new method, it is outside of my question. According to quantum mechanics, electromagnetic force is carried by virtual photon.

    "Quantum mechanics allows, and indeed requires, temporary violations of conservation of energy, so one particle can become a pair of heavier particles (the so-called virtual particles), which quickly rejoin into the original particle as if they had never been there. If that were all that occurred we would still be confident that it was a real effect because it is an intrinsic part of quantum mechanics, which is extremely well tested, and is a complete and tightly woven theory--if any part of it were wrong the whole structure would collapse."


    So, how can we explain mechanism of electromagnetic interaction without using the uncertainty principle?

  • Linda E. Hanson added an answer in Biomass:
    What can help prevent fungal adhesion to the inside of 125 ml glass flasks during shake culture assays?

    I want to assess biomass production, but am concerned about attachment of fungal tissue to glass, potentially altering my biomass results. Any suggestions on how to prevent this are welcome? 

    Silanizing the glassware has been suggested - does anyone know of any decent literature regarding the use of growing fungi/other microbes on silanized glassware? 

    Please and thanks! 

    Linda E. Hanson · United States Department of Agriculture

    On your initial question about siliconization, this has more commonly been used by the pharmaceutical industry.   Previous studies have shown that siliconization can reduce fungal adherence to flasks (e.g. Ugalde and Pitt 1983, Silicone coating to prevent accretion on glass walls by Penicillium cyclopium grown in shaken flask culture.  Trans. British Mycol. Soc. 81:412., http://www.sciencedirect.com/science/article/pii/S0007153683800990#).  However it is not an easy procedure to do (for example http://www.pharmaceuticalonline.com/doc/siliconization-0001).  The growth medium also can affect how much adherence you get (e.g. http://iai.asm.org/content/32/3/1234.short).  You might look at adjusting your carbon source to reduce adhesion.

  • Pascal GALON added an answer in Computational Fluid Mechanics:
    Anyone familiar with Richard Extrapolation in CFD?

    Hello all,

    I was willing to know how utility of Richard Extrapolation in CFD. I know it can be used for estimation of order of scheme by running numerical simulation for 3 different grid configurations.

    However what I am not clear of is how to use it to approximate results of higher order accuracy using lower order. Is it simply by the formula of Richard Extrapolation 

    A= 2^k A(h/2)-A(h)/ 2^k -1 

    where A is calculated using grid first and then 1/2^k.

    In real application does this mean if I calculate some variable (say Pressure in pipe flow) with grid size 100x40 and then by 200 x 80 then using results obtained and formula I can estimate Pressure with higher order accuracy?

    Is this correct or there is some other way how this is used (multi grid method or something like that)

    Thank You

    Pascal GALON · Atomic Energy and Alternative Energies Commission

    Concerning error and uncertainly estimate using the Richardson Method you can read this report : 


    by by Tao Xing and Fred Stern

    IIHR Technical Report No. 476

    College of Engineering
    The University of Iowa
    Iowa City, Iowa 52242-1585 USA