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

  • Patrick Druggan added an answer in Microbiome:
    Is anyone familiar with skin microbiome depletion using antibiotics in mice?

    I am planning a few experiments on skin microbiome in mice, and it requires me to deplete the microbiome on the skin. I have come across a few antibiotic treatments, but not on the skin so far. I would like to know if its doable by applying the antibiotics on the skin.

    I would be glad for any comments or suggestions on this! 

    Patrick Druggan · Synergy Health, Chorley, United Kingdom

    Fusidic acid topical application should reduce the microbiome substantially, though you might want to do a chlorhexidine scrub after shaving to bring the numbers down, then follow up with fusidic acid application

  • Roberto De Franco added an answer in Density:
    How to select the damping factor vetor?

    I  encountered an inverse problem described as following

    AX=b,     a ill-posed problem 

    where A is a matrix with n by m ,X is a vector with m by one,b is a vector with n by one.

    when we solve the equation,we will get the solver that is unstable because the condition number of  A matrix  is large.

    then some ones add the damping factor into the daigonal elements in matrix ATA.

    the least-square solver is


    If the vector X (we can say that the model parameters)contains only one kind  data, the apha we used can be constant.

    But the matrix A contains kinds of data that the scale of them varies very much(eg: the velocity 2000m/s,the density 2.65 g/cm3 ,so 2000 is much larger than 2.65),the damp factors to velocity and to density will be not the same.

    Please help me  with some useful ways to select the best damping factors!

    Roberto De Franco · National Research Council

    In my opinion the best way is an empirical estimate from data variance  model variance trade off cruve which you can construct with several runs each one with different damping factor. 

    After the runs on a wide span of damping factor you construct theTrade-off curve between the data variance and the model variance for the full range of possible values of the damping parameter; so, the optimal value of damping chosen at the lower left corner  (and/or minimum) of the trade-off curve, which yields the best compromise between misfit and model variances. In literature there are others  empirical shemes based on the analysis of trade-off curves of the the numerical and statistical results of the runs with different damping factor.

    As you claim in your case you have data which scales with different scale factor. In this case I advice you to rescale, (if the formulation of your inversion procedure allows it), the density or velocity of a 10^3 (similar an unit change) so the scales are comparable. 

    If you perform an integrated inversion (i.e. separate inversion as I suppose seismo-gravity) you can split the problem of optimal damping search in the corresponding  trade-off  curves analysis.

    Finally in your inversion I suppose that you are performing a joint seismo-gravimetric inversion in this case the dominant problems are a) the parameterization of the two model (how to) and b) the relationship between the two model parameter (it depend on the v-rho relationship is included in the inversion). 

    I hope it is useful for you 

  • Alain Celzard added an answer in Starch:
    How to increase the plasticity in starch polymer plastic?

    i am doing research in fibre reinforced plastic

    i am having problem with elasticity in starch polymer

    Alain Celzard · University of Lorraine

    For increasing plasticity, you need plasticizers ... Usual plasticizers for starch are water (the natural one), glycerol, ethanolamine, formamide, ethylene glycol, sorbitol, le xylitol, triethyl citrate, sucrose, stearic acid, polyethylene glycol, etc. You can go through these papers:

    K. Krogars, J. Heinämäki, M. Karjalainen, A. Niskanen, M. Leskelä, and J. Yliruusi, "Enhanced stability of rubbery amylose-rich maize starch films plasticized with a combination of sorbitol and glycerol," International Journal of Pharmaceutics, vol. 251, no. 1–2, pp. 205–208, 2003.

    M. Huang, J. Yu, and X. Ma, "High mechanical performance MMT-urea and formamide-plasticized thermoplastic cornstarch biodegradable nanocomposites," Carbohydrate Polymers, vol. 63, no. 3, pp. 393–399, 2006.

    F. J. Rodriguez-Gonzalez, B. A. Ramsay, and B. D. Favis, "Rheological and thermal properties of thermoplastic starch with high glycerol content," Carbohydrate Polymers, vol. 58, no. 2, pp. 139–147, 2004.

    But plasticization also requires mechanical energy, so using an extruder with a suitable screw profile is an excellent way of doing it in the presence of the aforementioned plasticizers.


  • Is there any connections between ANOVA and Discriminant Factor Analysis?

    For research in data analysis.

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences


    Some connections are there in between ANOVA and Discriminant Factor Analysis,

    Discriminant Function analysis is most related to MANOVA.

    MANOVA is,

    1.  This is just a Discriminant Factor Analysis in reverse.
    2.  You want to predict a set of continuous variables from one or more grouping variables.
    3.  This method is often used in an attempt to control familywise error when there are multiple outcome variables.
    4.  This method is questionable, but a popular one.

  • Can someone share a questionnaire about knowledge of pregnancy warning sign?

    I'm a nursing science student at Universitas Indonesia. At the moment I'm writing at my thesis about the differences of knowledge about pregnancy warning sign between primigravida and multigravida.

  • What are the best soft wares for primer design?

    Polymerase Chain Reaction is widely held as one of the most important inventions of the 20th century in molecular biology. Small amounts of the genetic material can now be amplified to be able to a identify, manipulate DNA, detect infectious organisms, including the viruses that cause AIDS, hepatitis, tuberculosis, detect genetic variations, including mutations, in human genes and numerous other tasks.

    Now I want to design primers for detection of cancer cells apoptosis by myself, and need help to guide me for a good soft ware. TQ

    Adnan Muzaffar · University of the Punjab

    You can use Primer 3 or NCBI primer blast tool

  • Fatemeh Zonozi asked a question in Gaussian:
    How we can prove mechanism of DA reaction with Gaussian?

    I have Gaussian out put data and I want to prove mechanism of Diels Alder reaction.Which item can help me?How we can prove the mechanism?

  • What is the main statistical method of calculating the Temperature Trend over specific point ?

    what is the main statistical method of calculating the Temperature Trend over specific point ?

  • How can I use electrochemical impedance spectroscopy to study batteries?

    I made a new battery.

    I did charge and discharge for this battery.

    Now I am going to study this battery by means of the electrochemical impedance epectroscopy method.

    But I do not know how I can use electrochemical impedance spectroscopy to study the battery.

    Hassan Yousofian · University of Yazd

    Dear Travis Thompson

    thanks alot

  • Fadhil M.Najib added an answer in Amperometry:
    Why is Ag/AgCl used as a reference electrode in amperometry?

    Most of the amperometric experiments done I have seen in different publications used Ag/AgCl as reference electrode. Why is it necessary to do? What is the advantage of using Ag/AgCl electrode over other materials or metals?

    Fadhil M.Najib · Sulaimani University / Kurdistan-Iraq.

       In addition to my answer above, if your question is why we use a reference electrode and why Ag/AgCl is particularly used? I add some information for you.  First why we use a reference electrode? because we don't other choices, we wish if we dont need it.  You know electrical circuit in order to work it must closed just like electricity you need two wires.  Here in Electrochemistry also we need two wires(here two electrodes) one of which is the measuring electrode, while the other, which we call it a reference electrode, must attain a constant potential in order not to interfere with the the mechanism of the measuring electrode( the detecting electrode).  Its work in the system is to close the circuit on one hand and we know that our measurement is against a known and constant potential, which is the reference electrode..
       The second part of the question, I assume, is why Ag/AgCl?  Although Ag/AgCl is not the best reference electrode, but it is more convenient than, for example Calomel, because it can be use as a thin wire which can be placed anywhere in the system without  taking a space.  I hope this addition will be enough.  The principle of a reference electrode is to have a device in the system  its potential remains  constant during your experiment, not necessarily Ag/AgCl or Calomel.
    Thank you and good luck  

  • Can anybody help me on carrying capacity in meditteranean protected area?

    I wonder how a carrying capacity in a vehicle overcrowded protected area could be developed. It is for a dry mediterranean peninsula under high seasonal touristic pressure.As it is a protected area (Natura 2000 site), how to develop a CC that will include not only parking places but the ecological impact?

    Alessandro Ferrarini · Università degli studi di Parma

    Martina, you can change your viewpoint.

    Instead of seeking a carrying capacity which is very hard to detect, you could look for an OPTIMIZED human pressure

    You can read:

  • Patrick Druggan added an answer in Ferrozine:
    How can I use EDTA to measure total iron ion with spectrophotometer by ferrozine method?

    And in which solution can I dissolve EDTA? What should be the ratio of ferrozine, sample and EDTA

    Patrick Druggan · Synergy Health, Chorley, United Kingdom

    Hi, wouldn't it be better to recover the the bacterial samples and measure the iron in the bacteria, medium and mineral, independently  by atomic absorption? 

    Why would the total iron be higher in the biotic sample? Wouldn't it be the same as there is neither a net loss nor met gain of iron from the system?

    You have also assumed that the affinity constant for iron for EDTA is higher than the siderophores. Is that a valid assumption? I can't say that it isn't, it is just a question that came to mind. 

    I think you need to make a mass balance for the iron, because it should have a constant iron concentration. It simply passes from the mineral to the medium to the organism.

  • How can I find the energy gap of a nanomaterial using UV data?

    I have a data for UV visible characterisation. Will any body share the how to find the enegy gap by plotting the graph..and if you have the excel sheet for x and y variables kindly contact me? thanks a lot...

    venkatesha babu kr rathnaiah setty · Government Science College, Bangalore

    Dear Avc

     Thank you very much, f(r) is Kubelka-Munk function, how o find the same, any mathematical expression to determine? kindly suggest for uv-absorption wavelength. data on TiO2.


    thank you very much for the tips given....I have uv data, absorbance versus wavelength, can I use the mentioned formula for k, if yes how to find the R? for Tio2

  • What are the universal markers for pulses?

    universal markers as a tool of DNA Barcoding

    Semir Bechir Suheil Gaouar · La boratoire Physiologie, Physiopathologie et Biochimie de la Nutrition, Université Abou Bekr Belkaid Tlemcen, Algérie et laboratoir Génétique Moléculaire et Cellulaire USTO

    I think specific SNP

  • Paul, D. added an answer in MATLAB:
    How can I have fluid properties in MATLAB library? for example LiBr?

    For using genetic algorithm method to optimize refrigeration cycle.

  • Ali Chaibakhsh added an answer in Fuzzy Logic:
    In fuzzy logic theory, all inputs are equally important and the same. Is it possible to give weights to inputs when we use ruled-based fuzzy logic?

    For example, can we use the results of AHP weights?

    Ali Chaibakhsh · University of Guilan

    In MATLAB fuzzy toolbox, it is only possible to weight the rules (in TSK), therefore you should apply weights on inputs externally and then use the weighted data for FIS.

  • Patrick Druggan added an answer in Bacterial Cells:
    What kind of interactions could be happening between bacterial cells and a strong oxidizing agent like ammonium persulphate?

    Is the reaction limited to cell walls or does the oxidation continue for endogenous compounds?

    Patrick Druggan · Synergy Health, Chorley, United Kingdom

    The radicals would attack the cell wall and possibly the cell membrane. The charge on the sulfate radical would prevent it diffusing through the cytoplasmic membrane. It can form the hydroxyl radical and this is even more reactive than the sulfate radical - OH radical has a reaction constant of 1 x 10^-85. This radical is so reactive that it does not diffuse far from th site of initiation.

  • Rakesh Manuka asked a question in Rice Transformation:
    What are the common agrobacterium strains used in rice transformation studies for better transformation efficiency?

    Role of agrobacterium strains in gene transformation studies.

  • Nisreen Sulayman asked a question in MATLAB:
    How to detect the cicular-like objects in an image?

    I want to detect circular-like (Blobs) objects in an image, what are all the possible features which can be used to recognize this objects?

    Any MATLAB code(s) is really helpful?

  • How can i isolate minichromosomal maintenance homologue from a stage-specific parasite and characterize the genes during DNA replication phase?

    Cell cycle studies

    Semir Bechir Suheil Gaouar · La boratoire Physiologie, Physiopathologie et Biochimie de la Nutrition, Université Abou Bekr Belkaid Tlemcen, Algérie et laboratoir Génétique Moléculaire et Cellulaire USTO

    creates specific probes, your question is not clear or precise thank you

  • Sriyogi Kottala added an answer in Supply Chain:
    Are there any papers focusing on the role of modularity in determining the power of supply chain members?


    Sriyogi Kottala · Guru Ghasidas University


    few papers available on th role of modularity determining the power of suppy chain 

    DELL DIRECT MODEL is very good example. Few researchers done work in this area.


    Happy Researching.


    Dr. SriYogi Kottala

  • What is the utility of DNA Barcoding in marine perspective?

    Thank you in advance for your answers.

    Semir Bechir Suheil Gaouar · La boratoire Physiologie, Physiopathologie et Biochimie de la Nutrition, Université Abou Bekr Belkaid Tlemcen, Algérie et laboratoir Génétique Moléculaire et Cellulaire USTO

    Hi, you can used to identified your population, used too tracability, identified migration flux and what ever!!!

  • Should the whole class be graded for collaborative team effort along with individual performance?

    In recent times interpersonal skills such as working in a team seems important for success.If so, should problems / assignments be set , which cannot be answered by one or two individuals but which would require a collaborative effort of many individuals.Student grades with class collaborative grade would give a measure of how the group as a whole may succeed in life. This may explain why some batches seem to perform better than others. This may be more relevant in Engineering, Business , Computer Science than in Mathematics or Art. It would be interesting to know if there are any research results on this.

    Imre Horvath · Delft University Of Technology

    Dr. Ramesh, I see your point and resonate with your reasoning. However, I think both the objective (in the current example, the objective of employment) and the tasks to be taken should be further articulated. I am aware of rather sophisticated personal profile assessment schemes (developed by psychologists) which give quite reliable personal characterization and are good indicators of fitness for a job.

  • Is there any rapid publication journals that are indexed by ISI or SCOPUS or both that cover the field of medical image processing?
    ISI rapid publication journals.
    Zohair Al-Ameen · Universiti Teknologi Malaysia

    Thank you very much Dr

  • Jorge Ruiz Carrascal added an answer in Amino Acids:
    What is the role of dil.HCl in extracting free amino acids?

    Why diluted HCl is being used by researchers while extracting free amino acids? When I tried extracting my plant sample with distilled water there was no difference in the extracted amino acids profile.  

    Jorge Ruiz Carrascal · University of Copenhagen

    By using water, anything thata is water soluble will be extracted, including water soluble proteins, so that if in the subsequent protocol you do not get rid of the proteins, they will be in the final extract injected to the GC or HPLC. By using diluted acids (usually sulfosalicylic acid), most proteins will be precipitated and can be easily removed by centrifugation and/or simple filtration.

    Moreover, the solubility of some amino acids in water is rather low, and using a water extraction procedure could lead to underquantifying these amino acids.   

  • How can i extracted vegetal DNA from agarose and acrylamide gel?

    Thank you in advance for your answers.

  • Is there anyway to link quantum mechanics measurement dilemma to Plato's Allegory of the Cave?
    Mohamed El Naschie · Alexandria University

    a quantum particle is a zero set given by o,phi  . a quantum wave is an empty set given by minus 1 , phi squard. when you  take mesurment   you convert instently an empty set into a zero set.for plato cave see scott olsen writing about E Infinity and cantorian golden mean spacetime

  • Tuan Anh Le asked a question in Circular DNA:
    How did circular DNA in Prokaryote be proved?

    I am a student and I am studying on Prokaryote's genome. I wonder circular DNA in Prokaryote proved by what techniques?

    Thank you!

  • Lior Kornblum added an answer in XPS Peak:
    What is the relevance of C correction in XPS analysis?

    I have taken the XPS of Ti3SiC2 and after deconvoluting the peaks, it shows the following peaks without any correction.

    for C1s at B.E.  281.1eV ( very small),  288.3eV ( medium intensity ) and 293.4eV ( high intensity)

    for Ti2p at 462eV, 466eV (high intensity), 472eV

    fro O1S at 539 eV ( intense) and 535eV ( less intense and broad)

    What may be the reason for the peak shift?

    whether the C correction is mandatory in XPS analysis? while doing the Correction which peak in C1s spectrum have to be considered? The one which is more close to the reference value or the most intense peak?

    I will be happy and thankful if anyone can help me to solve these questions.

    Lior Kornblum · Yale University

    The position of the peaks is way off. I'd guess that by about +3 eV.

    This is likely due to mis-calibrated spectrometer Fermi energy. You can calibrate it by scanning a clean sample of gold (usually Au 4f) or graphite (C 1s) and compare the peak position to the literature (NIST's XPS database is extremely useful). Charging could also play a role here but I haven't seen this to cause such severe shifts.

    As for your question - is correcting the shift of the binding energy important? It depends on what you are trying to get from your data. Sometimes I'm interested in the relative distance between peaks or a particular peak shape and then the exact absolute positions aren't very important.

    However, in this case the offset is so large that it may be challenging to properly identify the oxidation/chemical states of the elements. Moreover, if you ever want to publish these results - as a reviewer I would never let this pass with the energies being off so much.