ResearchGate Q&A lets scientists and researchers exchange questions and answers relating to their research expertise, including areas such as techniques and methodologies.

Browse by research topic to find out what others in your field are discussing.

Browse Topics

  • Ali Chaibakhsh added an answer in Steam Turbine:
    Can anybody help me to find different sizes for steam turbine tenons that already exist in Saudi Arabia?

    Dimensions of steam turbine tenons in KSA?

    What is the engineering method followed to design a tenon for steam turbines?

    Ali Chaibakhsh · University of Guilan

    such information are generally confidential and only could be found for example in KSA ministry of energy (or other organizations may be responsible). the best way to access such information is that your university send a letter and introduce you to these departments. then you may get the permission to access to these documents.  

  • What is the optimal interrelationship of cognitive and physical domains for successful language learning?

    The learning of a second language is a complex process.To teach a foreign language successfully you must know something about why one learns or fails to learn a second language.

    Jodi Tommerdahl · University of Texas at Arlington

    I find this an interesting discussion but understood the question quite differently.  I thought the question was referring to the biology of the speaker in having normal neural processing and having adequate ability to produce the variety of speech sounds required by the language (or the ability to sign).  Could you tell us what you mean by "physical domain"?

  • Syed Raza added an answer in 293T:
    Do 293t cells change morphology with media change?

    I have noticed a change in the appearance of 293 cells which I am using for my lentivirus preparation. As soon as I change the media from DMEM to OptiMEM the cells shrinks, and sometime they make a string (thread) like appearance. If they are growing isolated or not in enough confluence they they go off the bottom of dish. Infact, when last time I just replaced the old DMEM media with the fresh one then also a quite visible shrinkage appearance was their.

    I am not sure whether morphology change/ shrinkage is a normal phenomenon with 293 cells or it is just happening in my case. Please suggest.

    Many Thanks,


    P.S: before seeding 293, I coat the plate with fibronectin.

    Syed Raza · University of Utah

    Hi Matheiu,

    Many thanks for your kind reply. May be you are right, it may be mycoplasm contamination I will ask if anyone else have the 293 stock to double check.

    Many thanks


  • Taha R Adawi asked a question in Inventory:
    Abou schaefer the 192-item children's report of parental behavior inventory?

    Can anyone help in identifying number of items representative of every dimension in schaefer the 192-item children's report of parental behavior inventory?

  • Joshua D Croteau added an answer in Freezing:
    Serum and PBMCs from pig blood?

    Dear all,

    I am planning to do a immune response study in pigs and I have a doubt that I hope someone can clarify me:

    I need to get blood from the pigs and then extract serum and PBMCs (Peripheral Blood Monocytes cells) from the blood. Does anyone know whether I can freeze the blood and make up the serum and extract the PBMCs after freezing the blood?

    If someone can clarify my doubt I'd be really grateful.

    Thanks in advance.


    Joshua D Croteau · Johns Hopkins University

    You need to isolate the pbmcs from fresh blood. Within 4-8 hours of drawing is best to maintain viability. Also, for serum you will need a separate aliquot of blood to allow for clotting. If what you need is plasma, not serum, you can derive both from the same sample.

  • Costas Drossos added an answer in Geopolitics:
    From geopolitical point of view, how real is the possibility that Iran returns on global gas market and replaces Russian gas?

    With 18 percent of total world gas reserves Iran is right behind Russia....

    Costas Drossos · University of Patras

    It looks that oil has become a tool for sanctions, and international politics. Let alone that there have been wars for oil. Thinking to convert "oil" from a factor of instability to a factor of piece, there should be an international independent organisation which determines the prices and all related to oil. This is a dream but let us dream a little!

    Presently, I believe that yes, west can use Iran's oil to continuo pressing Russia.   

  • Dheena Vijakumar asked a question in Column:
    How to analyse C02 concentration using Gas Chromatography?

    Is it suitable to use helium as carrier gas and TCD as the detector?
    which type of capillary column should be used?
    column length,ID,thickness?

    Can I use distilled water containing C02 for the test?

  • Julie Hruby added an answer in Archaeology:
    How can we tell the pylos tablets were once only air dried after they have thorougly been baked in the final fire w/o archaeometrical investigation?

    The biscuit baking of clay is to avoid damage during the baking process I understand. Letting clay dry before a first low temp  burning is part of this. I also understand that w/o further examination from just plain sight it is impossible to state whether a piece of clay has been burned once or twice, the highest temperature will leave ist mark and overshadow previous baking. Is that correct? If so, how do we know the Pylos tablets were only air dried and not (half) baked?

    Thank You

    Julie Hruby · Dartmouth College

    No problem.



  • Determination of Contact angle?

    I want to measure the contact angle of my polymer surface, usually how it can be defined?

    please name device name or softwares

    Alexander J. Babchin · Tel Aviv University

    Look at the Wikipedia. Google in your question, this is traditional established field, ready instrumentation is available.

  • Tausif Alam 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.

    Tausif Alam · University of Wisconsin–Madison

    Ursula, in Peru there was an ancient practice of binding the skull to elongate them - the longer the better. Since your model seems to depend most heavily on the physical location of various interacting elements (neurons, individually/groups) producing a hologram like fields intersecting and interfering creating a resultant profile, what do you suppose happens as these internal elements shift with respect to each other, as they inevitably must in Peruvian scenario?

    Likewise, in case of benign tumors that gradually grow compressing certain segment of brain, similar issues as mentioned above will come into play. Not all such individuals forget their past or who they are at that point. In some cases, after resection of the tumor, they continue to retains their memory and other functions (resecting tumor allows an immediate availability of space where compressed tissue can relieve the pressure, yet another dislocation event for the regional neurons).

    How do you reconcile the impirical observations? 

  • Alaa Kareem Niamah added an answer in Fermenter:
    What is the best culture medium for growing lactic acid bacteria producing bacteriocin?

    i want to isolate LAB from fermented foods such as fermented sorghum that produces bacteriocins which can be applied on raw and cooked meat as a preserving strategy 

    Alaa Kareem Niamah · University of Basrah

    you can used whey protein as bacteriocin production media pH 6-6.5 

  • What is nuclear family in sociology?
    1. What is nuclear Family?
    2. What are the functionalist and marxist view about that?
    Aleksander Kobylarek · University of Wroclaw

    two generations: parents+children/child

  • Can you introduce me some references for values of mean and standard deviation of DG probability distribution function in a 24-h PS operation problem?

    I am going to model uncertainties exist inherently in a power system operation problem in the presence of renewable energies. Can you introduce me some papers as references for typical  values of mean and standard deviation of DGs(wind turbines, solar panels) and load probability distribution function  in a daily operation of an electric power system?

    I look forward to receiving your reply.



    Akbar Amirian · Tarbiat Modares University

    Dear Anislei,

    Thank you for your quick reply. However, these papers have been written in Spanish which is utterly incomprehensible to me.



  • Afshin Hamta added an answer in Spectrophotometer:
    Does any body know about the wavelength of heavy metals in spectrophotometer?

    what's the wavelength of metal ions (such as Fe(II) , Co(II) , Mn(II)) in spectrophotometery?

    How can i find them?

    Afshin Hamta · Iran University of Science and Technology

    Thanks for your answers.

    Dear Oğurtani i used your answer. Thank you

    Dear Cutright thanks for your guidance.

    Dear Najib the Instruments that you suggested was so useful. I wanted to use Uv-Visible Spectrophotometer but i found this Instrument can't detect Fe(II) and now i want to use ICP. thanks for your idea and guidance.

  • Jodi Tommerdahl added an answer in Speaking:
    What is the diagnos for a five-year old and with language impairment ?

    I have a case of a child in his 5 years and he can not speak , he can speak so little and his biological test of (brain , ear , articulation ) is perfect and had no septum of (down syndrome  , autism , ...) , he is a normal kid but without a good language acquisition , what is the name of this kind of case?

    Jodi Tommerdahl · University of Texas at Arlington

    Dear Avesta,

    I'm glad you have been able to get more information.  Please do write if we can be of any further help.


  • David Boansi asked a question in IT Infrastructure:
    What are some of the economic advantages and disadvantages of landlockedness (with reference to trade and growth)?

    It is generally perceived that due to lack of direct access to the sea, landlocked countries are primarily marginalized from major trade related networks and hardly benefit from trade opportunities due to their extreme reliance on their transit neighbors who may either have a weak or well-developed infrastructure (which have either detrimental or beneficial implications for trade and growth). Besides this usual perception most trade experts hold, what other advantages and possibly disadvantages are there for landlockedness?

  • Where in structure of block copolymer (like SEPS or SEBS) is grafted the maleic anhydride by reactive extrusion?

    I need to draw the structure of SEPS with maleic anhydride graft.

  • Claudio H. Morales asked a question in Convexity:
    Suppose X is a locally convex Hausdorff space and C is a convex weakly compact subset of X. Would this imply that X is a reflexive space?

    I trying to extend some results that hod true for reflexive spaces, and I'm wondering whether this assumption could be too strong in a general LCS.

  • What is this fluorescence material in DNA sample ?

    I extracted DNA from several hundreds blood sample by promega kit , one sample among all the others show a two clear fluorescent bands migrate to the negative pole , those bands appear without any staining just uv 310nm irradiation as in the gel image below . the bands color are red to orange ,
    Can anyone tell me what is this , why , any idea ,?


    Hayder Obayes Hashem · University of Babylon

    i do not think that the proteins have this ability of fluorescentation  , even if it denature ,

  • Do we need to set aside 35% of the planet as Ecological Restoration Preserves?

    Especially in places that experience frequent droughts, like the Western USA, India, Pakistan, the Middle East, North Africa, etc., should we plan on setting aside at least 35% of the area as Ecological Restoration Preserves, so that the watersheds keep produce adequate rainfall for our grazing and cultivated field needs in the rest of the lands?  We are so used to utilizing the natural world to the maximum for human needs, we may have crossed over a threshold recently and accidentally eliminated too much of the natural world that supports us, and we may be undercutting our own future survival ?

  • Geng Ouyang added an answer in Mathematics:
    What are “potential infinite” and “actual infinite”? Is there anything wrong with our understanding and the definitions to “infinite”?

    “Potential infinite” and “actual infinite” are really there in our mathematics and science, but it seems very difficult to understand and express these two concepts clearly and logically ever since.

    Why many researchers (such as researchers taking mathematics as a practical tool) refuse “potential infinite” but only accept “actual infinite”. Do we really need both “potential infinite” and “actual infinite” or just need “actual infinite”? Is there anything wrong with our understanding and the definitions to “infinite”?

    Geng Ouyang · MinNan Normal University

    Dear Mr. Erkki J. Brändas and Mr. David Yetter, thank you very much.

    Sincerely yours, Geng

  • What is the best method for the fabrication of a metal based composite and FGMs based on economic aspects, rate of production, and simplicity?
    Powder metallurgy, casting methods, thermal spray, spark plasma, which one is the best method for metal based composite and FGMs ? Why?
    If you can choose all methods at the time, for achieving the best properties especially mechanical like hardness, toughness, which one is your choice?
    Mostafa Saboktakin Rizi · Sharif University of Technology

    As Behzad said, powder metallurgy and thermal spray coating will produce very pores product and would not be good choice for electronic device. But there are other alternatives to produce dense composites, such as surfacing and Heat treatment and vapor deposition (PVD & CVD), Cladding, diffusion welding and so on.

    All in all, it is very important that; what are the materials chemical compositions? what is the shape of products? do you want to produce multilayer product with distinct interface? or do you need to gradient change in chemical composition?
    it doesn't have same answer and you should tell us clearly about that.

  • What simple outcome measure would you recommend to regularly measure parent rated change in global ASD ?

    Children will be having a variety of non-specific therapies, and the measure needs to be able to be completed by parents, and be considered valid and reliable.

    Kathryn F Jankowski · University of Oregon

    As a note, the SRS stands for the social responsiveness scale (which I mentioned above). There are two versions. Like several of the responders mentioned, the SRS2 is the most up to date. You can find it here: http://www.wpspublish.com/store/p/2994/social-responsiveness-scale-second-edition-srs-2

  • Costas Drossos added an answer in Primates:
    To whom the greatest invention belongs ?

    I mean intentional use of STICK. But this invention belongs to Humanoid Primats, not to Humans. Invention was so great, that learning handling the stick, primates became humans. No other invention led to transformation of species. 

    Other RG participants can have different opinion, we are here for discussion. 

    Costas Drossos · University of Patras

    Sorry Alexander, 

    I do not know what you are talking about!

  • Jason Glicker asked a question in Articles:
    Where do I find articles after I request the full text to be sent to me?

    The article I was looking for is 

    Moving as a gift: Relocation in older adulthood

    Tam E. Perry in
    Journal of Aging Studies: 2014

  • Rob Catlett added an answer in English:
    How do you decide what is good in an essay?

    My university is reviewing its assessment descriptors for EAP writing and speaking assessment. Th current descriptors require moderation and standardisation to ensure fair marking but I have found there is a significant range of interpretation of these descriptors. I would like to hear the thoughts of other practitioners in EAP and if possible examples of other descriptors from institutions that provide EAP courses for non-native English speaking students especially those that provide English medium instruction in non English speaking countries.

    Rob Catlett · Emporia State University

    Your question is interesting. We all face challenges in assessment ranging from purpose and consistency to applicability.

    The following short links may help as you encounter different perspectives at your university. Some of the quotes are real gems. Alex Nottingham (2013) has a cogent piece. A favorite assessment quotes in the first link is about assessment: “...a continuously improved means to carelessly examined ends...” (Merton 1964 p vi in Madaus, 1993) The second link addresses some of your concerns directly. You might note what Tevis and Popham observe: "Perhaps the most serious problem with alternative assessments in connection with grading is the difficulty in maintaining consistency among different students (Popham 1995). Realistically, though, the process of grading, with its inherent subjectivity and arbitrariness, is perhaps the major problem itself." Tevis continues: "Assessment conducted merely for accountability reasons is not instructionally sound. To be meaningful, the act of assessment must in some way enhance the learning process...” (Tevis 1996)

    Some of the experiences that changed my perspective on assessment were participating (i.e., as both a presenter and learner) in Higher Learning Commission (HLC) workshops and meetings on assessment. To condense a long story, we have used external professionals in addition to English professors to evaluate the work of our economics students at ESU. The external professionals use their organization's standards in evaluating and providing feedback on the student's work. Significant differences exist between English professors and high-level executives. Our students quickly learn that it is challenging to satisfy both. They also seem to learn much faster when they realize who is reading their work. This is one example of how assessment can accelerate the learning process.

    Although it may not as easily apply in your EAP program now as it does in our economics program, I can envision ways it might. The challenge is that it takes considerable time an effort on the part of the evaluators along with students being interested in the assessment as part of the learning process. I know this is more than you asked; however, your question is interesting and sparked an interest.

  • What is the difference between definitive and primitive HSC?

    I read paper "Wnt signaling controls the specification of definitive and primitive hematopoiesis from human pluripotent stem cells"----I confused that why primitive do not have T lymphoid potential?(the fetal T cells are from definitive HSC? )

    John Schloendorn · Gene And Cell Technologies

    I don't think "primitive vs. definitive" is a particularly high resolution model.  It has its historic origins in red cell hemoglobin switching, and may be useful for those cells.  

    When speaking about HSC, I'd rather break it down in terms of Aortic vs. Fetal Liver vs. Bone-marrow stages.  In order to be a long-term transplantable HSC, it must have multilineage potential, self-renewal, and bone-marrow homing.  

    Only adult-type, bone marrow HSC have those three characteristics together.  We don't presently know which markers might distinguish those cells from their non-transplantable, more primitive precursors. 

  • What are the best tools for simulation and modelling?


    I wanted to know what are good tools for simulation and modelling and does it really need a tool? Can't we build our own software for out own system?

    I am new to this field only thing i know is there are two parts is such system 1) mathematical modelling 2) Graphical representation ( Its my perception need not be true).

    So can we mathematical modelling implement using any object oriented language and for graphical part we can use some tool to reduce efforts and time.

    Also suggest me some material that must be required to enter into field of simulation and modelling.

    Thank you.

    Armin Fügenschuh · Helmut Schmidt University / University of the Federal Armed Forces Hamburg

    The first question is: what do you actually simulate. There are practically zillions of programs out there for simulating each and every special purpose. Some are more general, and very flexibel, but you need to write some code to adapt them to your purposes. Others are already dedicated for a certain application. Then you only need (and only can) specify some parameters to obtain a result. Less flexibel, but much faster in return. 

  • Andreas Leineweber added an answer in Transformers:
    Why is the hemihydrate gypsum (CaSO4 0.5H2O) transformed from anhydrite (CaSO4) different from that transformed from dihydrate (CaSO4 2H2O)?

    At temperatures above 200 degree C, the dihydrate phase transforms to anhydrite. The anhydrite phase can absorb the moisture and transform to hemihydrate phase again. But this phase is much different in properties from the hemihydrate which results from calcination of dihydrate between 40-170 degree C. I was wondering what are the exact differences between these two? And why are they both called hemihydrate? 

    Andreas Leineweber · Technische Universität Bergakademie Freiberg

    Some newer references; although one might be sceptical about the different space group symmetries proposed there. But the study goes into very much detail ...

    Investigation of the crystal structure of gamma-Ca S O4, Ca S O4 . 0.5(H2 O), and Ca S O4 . 0.6(H2 O) by powder diffraction methods

    Journal of Solid State Chemistry (1995) 117, p165-p176

  • Protein Extraction From Nylon Membrane?


    I am after a protein extraction from Nylon membrane protocol. I would like to identify the protein that caused a 'shift' during an electrophoretic mobility- shift assay (EMSA) by MS ?? Thanks!