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

  • Tobias Polifke added an answer in ELISA:
    Is it possible to unhook an antibody from a plate of a commercial ELISA kit?

    I know my question may seem odd. But here is my problem. I am trying to develop a sandwich ELISA on magnetic beads, but I have great difficulty in capturing and detecting antibodies that work together, hence my idea of ​​using the antibodies of validated commercial ELISA kits.

    However, most of the time the capture antibody is coated onto the plate and therefore cannot be used. Only the detection antibody can be used.

    Here is my question/idea: is it possible to unhook the capture antibody from the plate, while keeping its functionality in order to use it as a free capture antibody?

    Thanks in advance for your hints.

    Tobias Polifke · Candor Bioscience Gmbh

    Binding capture antibodies covalently to plates is not the common way of producing commercial ELISA kits. Covalently coupling is much to expensive and ineffective for kit manufacturers, so that it is used only seldomly for very critical and highly-priced kits in niche markets. Capture antibodies are simply "coated" on plates, which means they are simply adsorbed on the plastics surface. ELISA plate surfaces are optimized to be "sticky by adsorption" for antibodies. Due to the fact that only 2-6 % of coated antibodies on an ELISA plate remain actively binding (the rest is lost mainly due to conformational changes by denaturation due to the plastics-protein contact), it will be hard to get such antibodies off the plate again. Furthermore you should know that after adsorption onto the ELISA plate, kit manufacturers block the plate and afterwards they stabilize the coated antibody with a coating stabilizer like Liquid Plate Sealer or similar commercial solutions. This stabilization enables that ELISA plates can be stored for years without losing binding effectivity of the coated antibodies. The same stabilization process also works for coated beads. So if you like to store your beads, you could even use such stabilizers. But regarding the fact of the normal plate production process, I would not expect that you can get an actively binding antibody back from the plate from a kit. If so, it would be mixed with inactive and denatured antibody (much more than 90 %), blocker and stabilizer molecules. So you would have to intensively purify the antibody, before you re-use it for coating of your beads, because otherwise you would coat your beads with stabilizers and blockers instead of capture antibodies. Sorry, but I would say you should forget the idea of getting the capture antibody from a commercial ELISA plate.

  • Mahboobeh Shirazi added an answer in HMM:
    Does anyone have experience with Network Anomaly detection using HMM?

    I am developing HMM systems that detects network anomalies, I was referring to KDD cup 99 dataset but for a particular attack, can anyone give me an example of the possible observations and the hidden states on which the observations relate to?

    Mahboobeh Shirazi · Tehran University of Medical Sciences

    FMF is the best site for anomaly detection

  • Can expression of a protein vary based on the technique used? Between Western Blot and immunofluorescence?

    I need some help, because I have silenced a protein using lentiviral transduction particules, at least when I perform a western blot the protein is not there, but when I perform an immunofluorescence assay I can see it, actually I'm not sure if its just an inspecific signal o I'm doing something wrong. I fix the cells using PFA 4% in PBS and I permeabilize them using Triton 0.1%. I think it is not a problem with the secondary antibody, because I've already checked it. Can someone help me?

    Thanks in advance

    Valeria Marrocco · Sapienza University of Rome

    Try staining with the secondary antibody alone to check aspecific signal.

  • Sven F. Crone added an answer in Random Forests:
    Random forest applied to time series: Data-generated prediction model sometimes contains influence for a variable, what are potential causes?

    I am applying random forest to a time series with both fast and slow changing processes. I will also try time series analysis based on state space models later, but for now I am curious of potential causes to the intermittent results that we obtain. 

    We study the effect on an optimization algorithm that according to knowledge-based models yields up to 7% savings in fuel consumption. Since this is data from ocean-going vessels, the control over the experiments is limited. 

    Essentially, we apply a low-pass filter to the time series data and then consider each measurement to be independent (that is, that the auto-correlative effect is negligible). I use the R caret package and has swept over different configurations of non-overlapping roll mean windows (low pass filter), different number of classification trees, different number of partitionings of data. The influencing variable where we want to check data is if an optimization of a control algorithm gives fuel savings or not.

    The problem is that there appears to be random if the prediction model has an influence from the optimization or not. My hypothesis is that this depends on the randomness in combination with that the optimization has a small effect (my guess is that it is close to the error of the measurement). So, when sweeping over the configurations, I get models with and without influence from the optimization.

    Any clues? 

    Sven F. Crone · Lancaster University

    Ok, thx.

    Note that in machine learning the term "Decision Tree" is used for a family of machine learning algorithms of ID3, CART, C4, CHAID  (see also Quinlan, J. R., (1986). Induction of Decision Trees. Machine Learning 1: 81-106, Kluwer Academic Publishers) which are the algortihms used to constitute random forrests (see above).

  • Are all frames of reference truly equivalent?

    In cosmology, the rest frame for the cosmic microwave background (CMB) appears to be a preferred frame of reference. For example, galaxies tend to have an average speed of zero relative to their local CMB rest frame. If an observer is traveling at a relativistic speed relative to the local CMB rest frame, the galaxy density would not appear homogeneous in all directions. Also there would be a substantial CMB anisotropy (unequal photon pressure) which opposes motion relative to the local CMB rest frame.

    Now, ignoring the anisotropic effects of the CMB, is there any reason to believe that the laws of physics would not be the same in all frames of reference? For example, if a fundamental particle has relativistic kinetic energy exceeding Planck energy (about 2×109 J), then its de Broglie wavelength viewed from the CMB rest frame would be less than Planck length. Is this possible? Is it possible that experiments conducted in such an extreme frame of reference would find noticeable differences in the laws of physics? For example, would QED and QCD operations which depended on virtual particle creation and destruction be affected?

    Charles Francis · Jesus College, Cambridge

    Daniele, do you really mean to tell me that the room in which you find yourself, and the clock on the wall, has no meaning? An extreme point of view, that one, I would say.

  • Has anyone tried to use self-adaptation and self-organization at the same time in multi agent systems?

    Self-Organization has a bottom-up process and Self-Adaptation has a Top-Down process. It may cause kind of conflict.

    Amin Rahmanzadeh · Shahid Beheshti University

    Dear Jan-Philipp,

    First of all thank you so much for your answer. In the case of difference between SO and SA, I think SO systems are adaptive but not Self-Adaptive. I mean there is no knowledge base. In case of different flow of controls, it is correct that in a SA system the MAPE-K loop can be implemented in different levels based on what you need. But, in a SO system the whole control is done by adaptive agents themselves. I mean it is limited to the lowest or micro level of the system and the results show up in system's macro level. 

    But the differentiation you mentioned as Strong or Weak SO is in conflict of my thoughts. I'm so grateful for that and I'll search more about it. Is this the resource you mentioned: Self-organization in multi-agent systems
    G Di Marzo Serugendo, MP Gleizes… - The Knowledge …, 2005 - Cambridge Univ Press ??

  • Can anyone help with SEM image detail interpretation?

    Can anyone help with  SEM image detail interpretation, for example:

    what is the meaning of WD ?

    what is the meaning of Det:Sec ?

    what is the meaning of Det:in Beam?

    what is the meaning of HV:13.0 kv?

    Abbas Rahdar · Zabol University

    Dear Maria,

    I am very happy from your message.


    Abbas Rahdar

  • Ahmed Yamin added an answer in Ebola:
    Is there a modified recommendation on breast feeding in EBOLA epidemic areas?

    As of any other infectious disease like HIV, is there any new breast feeding recommendation and guideline applicable in EBOLA epidemic areas?

    Ahmed Yamin · Dijla University College

    Hi Zelalem it is quite clear that ebola virus disease remain in the body fluids about three months especially in the seminal fluid for this reason it is not recommended to resume breast feeding to babies from infected mothers before the elapse of not less than three months after recovery .

  • Arun Prabhu Dhanapal added an answer in Plants:
    Where can I find crop parameters for Rye?

    I am currently undertaking a research on the failure of cereal plants, and would like to use Rye parameters such as ear area, root plate diameter, dry natural frequency, number of shoots per plant, etc.

    Kind Regards

    Arun Prabhu Dhanapal · University of Missouri

    You should able to find some of those information in following websites




  • Charles Francis added an answer in Physics Theory:
    If the wave functions of the Universe were infeasible, would they correspond to any element of physical reality?

    Does it imply that if the theory did not allow calculating values of the given quantity in reasonable time, then this theoretical quantity would not have a counterpart in physical reality? Particularly, does this imply that the wave functions of the Universe do not correspond to any element of physical reality, inasmuch as they cannot be calculated in any reasonable time? Furthermore, if the ‘computational amendment’ (mentioned in the paper http://arxiv.org/abs/1410.3664v1) to the EPR definition of an element of physical reality is important and physically meaningful, should we then exclude infeasible, i.e., practically useless, solutions from all the equations of physical theories?

    Charles Francis · Jesus College, Cambridge

    Arkady, I cannot understand why you seem to think what I have done is somehow different from what you have called the Copenhagen interpretation, except that what you call wave function collapse is merely a change in probability when an outcome has been determined. Otherwise, in the form in which you described the Copenhagen interpretation, which I call the orthodox interpretation, it is correct in so far as it goes, and it is what I have used. Only, if you say that the orthodox interpretation has established relations between the maths and the underlying physical reality, it has not. It has only established relations between the maths and the measurements. This is one reason I have felt it necessary to develop the interpretation, and see what can be said over and above the orthodox interpretation.

  • If you could measure machine intelligence like a humans IQ, what would you measure and how?

    What level of intelligence do machines actually need/posses and how can this be compared. If the community is to create a Machine Quotient (MQ), how would this be compared to human cognition?

    Thelma Vance · Northcentral University

    The question should be directed at how useful the algorithm might be as measured by its ability to respond to external events quickly, perform tasks effectively using some form of discovery process.  Have you been following the algorithm that was elect to the Board of Directors with voting rights? 

  • Arbab I. Arbab asked a question in Magnetic Field:
    Does Biot_Savart law is applicable to charges associated with bosonic particles?

    Biot-Savart law gives the local magnetic field produced by moving charges. It doesn't distinguish whether the particle (charge) is fermion or boson, thought it implies implicitly that the particle is an electron (fermion). If the moving charge is a boson, how does this field look?

  • How do Vector Fields relate to Differential Operators?

    It seems as if there are two different stories about ordinary differential equations. On one had, a system of first order differential equations corresponds to a vector field, and a higher order differential equation is equivalent to a system of first order differential equations. On the other hand, a higher order differential equation may be solved by the method of Green's functions, which considers the left-hand side to be a differential operator, and the right-hand side to be a driving function (in particular, a delta function). I am wondering whether there is a theory that relates the vector fields to the operators in these two stories.

    Costas Drossos · University of Patras

    Have a look at:

  • Does anyone use a plasmid vector suitable for mammalian expression by non-viral transfections?

    Does anyone use a plasmid vector suitable for mammalian expression by non-viral transfections, and having the following features:

    -GFP following an IRES site and not as a fusion with the gene of interest (insert)

    -Puromycin resistance gene

    -Biotin tagging system

    -suitable for genes about 3kb

    Anuroop Venkateswaran Venkatasubramani · Institute of Genetics and Molecular Medicine

    Hi devdu.. I guess this is pretty late but yeah, I use lipid transfection method.. And I use TAL plasmids but it does not have an IRES site.. I guess you could insert it.. and the resistance marker is Amp..

  • How good is "Coefficient of Determination (R-Square)" in case of non-linear regression ?

    Does "Coefficient of Determination (R-Square)" provides sufficient information on how will the data fits a statistical model (line/curve) in case of non-linear regression ? 

    I would like to know whether there are other parameters that are more efficient ? 

    Does norms (Lnorm) serve the purpose better?

    Any help is appreciated.


    Rajesh Alayil · Indian Institute of Technology Madras

    @ Okafor, thanks for the info. I will do that and get back to you.

    thanks & Regards,


  • Do you have resources for Medical Evacuation Insurance for West Africa?

    We are getting ready to deploy to West Africa and there are many issues with insurance providers right now. Any help in this regard would be most welcome! Thank you!

  • Nishant Shetty added an answer in NMR analysis:
    Recently, I have isolated a novel compound with slight impurity. Shall I purify it or proceed to NMR to disclose its structure prior to purification?

    I have isolated a novel compound from fraction library and there is a slight impurity which is detected using LC/MS analysis, where a small ion peak is detected besides the molecular ion peak. Thus, I am hoping to get some opinion from RG members for whether purification work should be done now or shall I proceed to NMR analysis for structural disclosure before any further purification? As such minor impurity in the main compound might not have a significant effect on NMR spectra measurement. FYI, the amount of the compound I obtained is less than 2 mg.

    I would greatly appreciate for any advice, suggestions or comments. Thanks in advance. 

    Nishant Shetty · Texas A&M University

    I would definitely vote for collecting the 1D and 2D NMR data first.

    If the LC/MS data came from a high resolution mass spectrometer, the processing software may allow you to generate a molecular formula for the compound of interest. Getting an estimate of the number of carbons and hydrogens in the molecule can help you with interpreting the NMR data.

  • What's the interpretation of single photon interference in a double slit experiment?

    I want to know what are the reasons of this interference.

    How does quantum mechanics look for this interference? Does the photon interfere with itself or are the waves accompanied with it interfering with each other?

    What's the relation of wave particle duality with this experiment?

    What are the most acceptable interpretations of this experiment?

    Johan Frans Prins · Sage Wise 66 (Pty) Ltd

    It is a pity that lasers did not yet exist in 1927, before the Voodoo of "wave-particle duality" was formulated as if it is real physics. Just like a pure laser pulse, a photon is also a coherent wave with a SINGLE frequency. The difference between a laser pulse and a photon is that the laser pulse has continuously distributed electromagnetic-energy with a total energy E that is far more than the energy of a photon. The photon ALSO has continuously distributed electromagnetic energy, but its total energy is ONLY h*(nu). In all aspects it is a light-wave. The reason for this is that there are not sources possible that can emit less than this energy, and also not detectors that can detect less than this energy.

    When a coherent photon wave encounters two slits it moves through both slits as it must since it is a wave, and the two lobes that form on the other side interfere to form a diffracted wavefront;  as all coherent light waves do; no matter what their energies are.

    However, it is not possible to detect parts of this extended photon-wave since the minimum energy that can be detected is h*(nu). A detector that can do this is atomically sized, and the photon wave can only be detected on the screen by leaving a spot. If you try and detect through which slit the "particle" has moved, the detector collapses the two lobes directly after they emanated on the other side. They cannot interfere and the wavefront that reaches the sceen is not a diffracted wavefront anymore.

    Can a photon collide as if it has a centre-of-mass: Of course it can do this since its distributed EM energy is according to Einstein mass-energy. Any distributed mass has a centre-of-mass, and it is easy to prove by using Maxwell's equations that when a coherent wave does not spread into different directions, this centre-of-mass moves with a momentum p=mc. Thus, when a photon wave does not resonate with a detector which absorbs it, it can collide elastically with another entity.

  • Thanh Nguyen asked a question in Lysis Buffer:
    Can bacterial DNA extracted by boiling with DI water or Lysis buffer be used in qPCR?

    I am planning on running qPCR but with bacterial DNA. Will the qPCR work with the DNA extracted by boiling culture with DI or lysis buffer? Or I have to extract the genomic DNA using the kit (Purelink)?

    Thank you.

  • Alfonso. H. Del Rio added an answer in Marantaceae:
    Which primers are commonly used for the RAPD analysis of marantaceae (Maranta arundinacea)?

    Can the primers used for the RAPD analysis of zingiberaceae be used for the family marantaceae?

    Alfonso. H. Del Rio · University of Wisconsin–Madison

    RAPD markers are not species-specific markers, though some primers work better than others in terms of resolution or generation of polymorphic fragments. But essentially any 10-mer sequence  has the potential to work.

  • Franz Strauss asked a question in Macrophage:
    Does anyone know why i dont see any statisatical differrences in surface markers after different MOI of E. Coli DH5 in THP1 derivated Macrophages?

    Any ideas? or just because CH5alfa is considered non patogenic.

  • Lee Jibin added an answer in C-Reactive Protein:
    Is there any relationship between the C-reactive protein levels in peritoneal or bronchoalveolar fluid and the improvement of a systemic inflammation?

    I know that the levels of pro-calcitonin and C-reactive protein in serum have a relation with the improvement of sepsis, but I would like to know if the same relationship exists in peritoneal and bronchoalveolar fluid. 

    Lee Jibin · The Chinese University of Hong Kong

    is it a langitudinal design study?

  • Climate mitigation action?
    What must happen for people to reduce and remove greenhouse gases from our atmosphere?

    Hi Ann,

    I have been thinking about that problem almost as long as I have owned my copy of the 1999 edition of your book "A Climate Modelling Primer", ~15 years.

    But the answer is here dating from 1989!

    "On the one hand, as scientists we are ethically bound to the scientific method. ...
    On the other hand, we are not just scientists but human beings as well. ... To avert the risk (of potentially disastrous climate change) we need to get some broad based support, to capture the public imagination. That of course means getting loads of media coverage. So we have to offer up some scary scenarios, make
    simplified dramatic statements and little mention of any doubts one might have. ...
    Each of us has to decide what the right balance is between being effective, and being honest."
    --Stephen H. Schneider, author of the book Global Warming (Sierra Club), in an interview in Discover Magazine, October 1989

    I think that no action will be taken until people are scared. And for that to happen then the scientists have to be scared too. Moreover, they have to be prepared to be called alarmists and Chicken Littles. That is the technique the fossil fuel funded think tanks use to discredit the scientists.

    The problem is that the scientists won't face up to the dangers that are there. We know that only 10,000 years ago, as the sun in the NH was becoming stronger, there was a rapid rise in temperature that may have happened in only three years.  Temperatures in Greenland jumped by up to 20C in that time [Alley, R. (2002) The Two Mile Time Machine"], and the stadial which had brought an ice sheet to Scotland ended. (Scotland may still be cold, but not that cold :-). There were even corrie glaciers in the Lake District of England.

    Since it was abrupt, it came with no warning. A repeat of that event would mean an end to the Greenland Ice Sheet. It is already melting. But we do not know what caused that abrupt rise in temperture. Wally Broecker has suggestied it was caused by a retreat of sea ice from the Nordic Seas.Broecker, Wallace S. 2006. ‘Abrupt Climate Change Revisited’. Global and Planetary Change 54 (3): 211–15. Could a sudden retreat of the sea ice in the Arctic cause another rise of 20C in Greenland. That would result in a rise in sea level of 6m/20 feet. How would New Orleans or New York cope with a hurricane if that rise in sea level had happened? How would the Antarctic ice shelves behave if sea level rose by 6m?

    And that is just sea level. Drought is already affecting the Horn of Africa and California. So long as scientists say we don't know if it is caused by climate change then no action will be taken. We have to be honest and say, yes it most likely is caused by climate change. If we wait until we are sure, then it will be too late to take action!

    The problem is that it will take a paradigm shift for scientists to accept  that mankind is in danger, and that happening is well nigh impossible.

  • Rani Brooks asked a question in Benzyl Alcohol:
    Does anyone have access to UV/vis spectra for 1-phenyl ethanol?

    synonyms: Methyl phenyl carbinol, styrene alcohol, alpha-methyl benzyl alcohol. CAS: 98-85-1

    Specifically, I need the extinction coefficient at 230 nm, perhaps for any peaks and troughs in the 210-400 nm range.

  • Nicola Pedroni asked a question in Stochastic:
    Can anyone help me on the topic "Stochastic methods for solving the problem of a rod with random elastic properties"?

    I am quite "new" in this kind of problems: can anyone provide a "list" of (possibly recent) methods (so that I can look for more details by myself) and/or proper references that can introduce me into the subject?

    Thank you very much.

  • Joachim Pimiskern added an answer in Filing:
    Does anyone know CHM (Compiles HTML files) and what is the best tool for generating CHM file?

    I have new task to prepare CHM for an API I'm working with. I need some suggestions and helpful articles regarding CHM. Thanks

  • Valerio Piscopo asked a question in NIH 3T3 Cells:
    What are a good positive control primers for a NFkB ChIP on 3t3 cells?

    Hello everybody,

    I'm doing a ChIP on an HA-tagged NFkB tranfected in NIH 3T3 cells.

    For the qPCR I need a gene that is expressed in this cells and whose promoter is bound by NFkB. This will be my positive control.

    Thank you

  • Caroline Taylor added an answer in Heavy Metals:
    What amount of heavy metals ( lead , arsenic, cadmium, mercury ,….) in spirulina is safe for humans( maximum )?

    FDA defined amount of heavy metals for spirulina but  cocentration of heavy metals in market are more than FDA definition and some countries dont have standard or upper level for these

    Caroline Taylor · University of Bristol

    There are now thought to be no safe limits for these heavy metals: there are probably adverse effects at all levels.

  • Baptiste Lacoste added an answer in BBB:
    What is maximum size of particle that can cross BBB(Blood brain barrier)?

    I want make nanoparticles go across BBB so for that I want to know the threshold for the same.

    Baptiste Lacoste · Harvard Medical School


    Look at our recent paper and its supplementary data. With studied the cut-off size.