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

  • Joseph Dubrovkin added an answer in Chemometrics:
    I'm looking for Indian professionals in the field of chemometrics for joint activities in the framework of cooperation between India and Israel.
    Joseph Dubrovkin · Western Galilee College

    Dear Prakash,

    Unfortunately, I can not tell you anything about this project.

    Regards, Joseph

  • Jürgen Denecke added an answer in Food:
    What is your opinion from this picture?

    Open food on the roadside is not suitable for our health. 

    Jürgen Denecke · University of Leeds

    I disagree, if I'm driving on the road and I see I can buy some fresh mango juice just by stopping the car and spending a few rupees to get it there and then, it is good for my general wellbeing :) But if I see a stand with old samosas full of flies on them, well even if I'm really hungry I will not buy them. This can happen in your own kitchen as well if you don't cover the samosas after frying them in oil, so the roadside is not to be blamed. Roadside selling is a sustainable way for local people to earn some extra money without spending much resources in transport. It is healthy as long as people are sensible :)

  • Alireza Talebian added an answer in Dental Implants:
    What are your criteria for choosing an implant system?

    There are so many implant systems in the market and all of them say that their system is the best one. Also there are so many papers in the literature about the success rate of more than 95 percent for every system. When I search the internet about implant systems I become confused to choose the best one. I think no system can be chosen as the best one but there should be some criteria for choosing a good system.Do you agree with me? 

    What are your criteria for choosing a good implant system?

    Alireza Talebian · Isfahan University of Medical Sciences

    Dear Prof Galil and Dr Nesma El-Amier

    Your answers are good and I am waiting to read more answers from other colleagues.

    KIndest Regards

  • Prosenjit Pramanick added an answer in Plants:
    How plants are strongly alive in this sandy area?

    Generally sandy area is not suitable for plants.

    Prosenjit Pramanick · Techno India University

    Respected Denecke, 

    Do you know the characteristics of Ipomoea pes caprae ?

  • Can anybody suggest the digestion procedure for Zirconium Dioxide and Titanium Dioxide?
    Zircon(ZrO2) and Rutile(TiO2) are minerals containing zirconium and titanium respectively, its digestion is not so easy. Can anybody suggests the proper digestion procedure for these minerals?
    Bruno Lemière · Bureau de Recherches Géologiques et Minières

    Best choice is alkali sintering (for instance LiBF4) before digestion. 

  • How does fuel flow rate affect flame temperature in a combustion process?

    when burning fuel in combustion system, what influence  does a change in fuel flow rate have on flame temperature.

    Kamal Nasreldin Abdalla · University of Khartoum

    As Maddali mentioned fuel flow has to match air flow and the best is to get stoichiometric mixture if you are intersted in  a high temperature. However if the fuel flow rate exceeds the required stoichiometric amount then the mixture will be rich in fuel. If this mixture is burned incomplete combustion occurs resulting in low combustion temperatures. If the fuel flow is reduced beyond stoichiometric amount the mixture becomes lean and also incomplete combustion exists resulting in low flame temperatures.

  • Stefan Beckert added an answer in Abdominal Wall:
    Which prosthetic mesh works best for abdominal wall reconstruction following extended tumor resection?

    As a result of extended tumor resection, tension-free abdominal wall closure sometimes is not possible anymore.

    Which prostethic mesh is going to work best? In my experince, wound infection is a major issue here.

    I would be happy to share my thoughts with collegues also working in this field.

    Stefan Beckert · University of Tuebingen

    Dear Dr. Garcia de Polavieja,

    many thanks for you reply. I agree completely with on biomeshes. However, in the contaminated situation, abdominal wall reconstruction seems to remain problematic.

    All the best,


  • Shilendra Kumar Sharma asked a question in VASP:
    How does calculate polarization and dielectric using VASP code ?

    Does anybody know any reading material for calculating polarization and dielectric properties ?

  • Sudha Balagopalan added an answer in Transformers:
    I have studied that the secondary turns of a transformer should be multiple of four. Is there any reason?


    Sudha Balagopalan · Vidya Academy of Science & Technology

    Thank you, sir for the revelation from the book. This is how, us teachers can help the young students to always uphold the truth against myths perpetuated by quack kind of handling of engineering education.

  • Ahmed S. Moharram asked a question in Catalysis:
    Does H2PtCl6.xH2O solution stable for long time?

    I have a solid sample of  H2PtCl6.xH2O. It is known that this compound is highly hygroscopic and difficult to handle during weighing so i want to dissolve the whole sample in a known volume to store it for further use. 

  • Why is 70% ethanol used for wiping microbiological working areas?
    Why not 100% ethanol or methanol? Can anyone explain the mechanism of action?
    Ali Estaji · University of Tehran

    b) 90% ethanolwill evaporate fast
    c) An ethanol percentage of 50-80% destroys the cell wall/membrane of bacteria by denaturing their proteins and dissolving their lipids. Effective against most bacteria, fungi and some viruses; ineffective against bacterial spores. Therefore, the ethanol has to pass the bacterial membrane/wall to get into the bacteria - if you use 100% ethanol instead, the bacteria get 'sealed' and they will survive... Another mechanism is the high osmotic pressure of ethanol/water-mixtures; and the 70% has the highest one.
    d) Less expensive
    e) Safer flammability level

  • Ahmad Bazzi added an answer in Array Processing:
    What is the expression for array factor of an array with faulty elements?

    Hello all,

    I want to find the expression for the array factor of an array with faulty element. . 

    I referred a paper which says the array factor for the faulty element will be equal to the array factor for the entire array + (a term containing current magnitude and phase error in faulty element)...

    Is this a correct way??

    Ahmad Bazzi · Institut Mines-Télécom

    Dear Kishan,

    You can add to what you said a spherical configuration in 3D

  • Can I transform performance of mice in a behavioral test into a cognitive score?


    I have a group of mice that I have tested at different time points before treatment and after treatment and I want to see if their cognitive perfomance becomes better after treamtent across time. Is their anyway that I can transform their performance in every test into a cognitive score and then compare it across time.

    Thank you so much.

  • Antonio Curcio added an answer in Troponin:
    What is the best time point to assess PKA target phosphorylation after stimulation with isoproterenol?

    I would like to assess phosphorylation of PKA targets like phospholamban and troponin in isolated rat cardiomyocytes after stimulation with isoproterenol. Is there an optimal duration for stimulation to get detectable but not yet maximal phosphorylation?

    Antonio Curcio · University Magna Græcia, Catanzaro, ITALY

    Hi Tim, in 60 seconds you activate B-AR. Ascorbic acid is required for vehicling ISO.

  • Dominique Liger added an answer in Yeasts:
    Can intact circular plasmid integrates into Genome of Yeast S. cereivisiae?

    I want to design an experiment to confirm that my S. cerevisiae URA3 gene can function in S. cerevisiae.

    My plasmid that is a BluescriptiiSK+ harboring S. cerevisiae URA3 gene (and don't has any ARS or 2 micro ori or other yeast gene or sequence). Since, This plasmid have a homolog sequence of Sc URA3 gene so I think maybe it can integrate into yeast genome.

    The problem is I cannot find the restriction site that cut only one point on URA3 gene. So, I have to transform an intact circular plasmid into S. cerevisiae.

    1. Is it possible to transform an intact circular plasmid to integrate into yeast genome?

    2. What method that I should use for transformation? LiAc?

    3. What is the quantity (amount) of plasmid that should use for transformation?

    or Any suggestions, Please provide.

    Best Regrads,


    Dominique Liger · Université Paris-Sud 11

    I've checked the ura3 deletion construct from the Brachmann paper (http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291097-0061%2819980130%2914:2%3C115::AID-YEA204%3E3.0.CO;2-2/epdf), indeed the deletion is more than the ura3 coding sequence (roughly it runs from -220(towards ATG) up to +80(towards stop codon). So if your full  gene sequence lies only within this window there is no chance to get homologous recombination.

    To answer you latter question (complementation of ura- strain from a stable yeast plasmid), to get positive result you need your gene to be autonomous on the plasmid (efficient yeast promoter and terminator sequences must be located upstream and downstream of the gene coding sequence).

    As you expect your ura3 gene to be functional, why don't you just sequence it to compare it with wild type?

  • Mirko Schmidt added an answer in User Modeling:
    Is there a standard conceptual/concrete personalization model which accounts for cognitive variables?

    I am trying to understand if there are existing Recommender Systems which Personalizes a User Model bases on Cognitive Variable and VALs (Values, Attitude, Lifestyles).  

    Are there any standard Conceptual/Concrete Personalization User Model which accounts for Cognitive variables?

    Is anyone working in this area?



  • Abdelkader BOUAZIZ added an answer in Formic Acid:
    Does anyone know about polyamide 66 (Nylon66) Hansen solubility parameters (HSP)?

    There are different values reported in the literature!

    The strange thing is that formic acid is an excellent solvent for PA66, but all the reported HSPs are far different from those for formic acid. The R-value (gyration radius, dissolution distance) for formic acid with respect to reported PA66 HSPs is even greater than two, but it dissolves PA66 readily! While, regarding HSPs, it should not dissolve!

    Any explanation/suggestion?

    Abdelkader BOUAZIZ · Univ. Ibn Khaldoun Tiaret

    Dear all;

    the attached document is the only downlable page of the aforementioned link. Regards

  • Why does dilution of homoeopathic medicines enhance their potency? Is this not against scientific phenomena?
    I have been told by homoeopathic practitioners that dilution and potency of homoeopathic medicines is inversely proportional. This means the higher the dilution the more potent the medicine will be and vice versa. I have doubts which may be due to my bias because personally I did not find any experience of homoeopathic medicine effective.
    Barry Turner · University of Lincoln

    The National Health and Medical Research Council of Australia published this excellent report in March this year.  The study was carried out by responsible scientific method and concluded that homeopathy was useless except as placebo.  

    The NHMRC have little to gain by coming to that conclusion if it is incorrect.  If homeopathic medicines worked huge amounts of money could be saved and Australians would all be healthier. 

    Of course, it is open to the extremely wealthy homeopathic industry to carry to experiments or meta-anayses to rebut the study.   Until then we will have to continue seriously questioning why they prefer to rely on testimonials and panegyrics instead of science.

  • Tomy Patzelt added an answer in Philosophy:
    Can ethics be measured objectively?
    Ethics, ethical committee, ethical approval and other ethical related words are extensively used on Researchgate and other places. How to define and measure ethics in objective bases?
    Tomy Patzelt · Czech Telecommunication Office


    You are right, of course. I just wanted to describe examples and not to provide exhaustive list. I think we had the whole book on these codes, describing them in detail. When I worked in the field, then one of our customers required specification of prices both acc. to "ex-works" and "CIF" codes in order to compare if vendor didnt intended to cheat f.inst. on transport prices. .-))))

    However, all above mentined doesnt solve initial question if it is ethical to ask for payment if one of concerned parties disagrees with paid money or with provided services.

    It only creates framework for "objective" decision of the court of for ADR (Alternate Dispute Resolution), when one of concerned parties decides to submit charges or complaint.

  • Mahboobeh Parsapoor added an answer in Machines:
    As I am novice in machine learning, Can anyone please suggest me how to learn the subject well enough to carry out further research in the area?

    Research now a days in Artificial Intelligence is concentrated on bridging the gap between biological learning process and machine learning.Many algorithms have been developed which uses their past experiences to predict and forecast the future outcomes but none of proposed algorithms have much intelligence to dominate the human intelligence but it is supposed to be done soon.Mapping of human emotions and biological learning in machine language will prove to be huge breakthrough in this area.

  • What are the benefits obtained when HHO gas mixed with gasoline is used in engines?

    HHO gas can be produced from water electrolysis.It contains a high percent of hydrogen and oxygen and can be mixed with gasoline in the engine intake.

    Kamal Nasreldin Abdalla · University of Khartoum

    Thanks Govind and Stefano. But Govind what do you mean by combustion chamber efficiency is it the same as engine efficiency mentioned by Stefano ?

  • Ghadir Fouad asked a question in Cooperation:
    Any scientist from Czech who wishes to cooperate with Egyptian scientists in a project funded by the Egyptian academy of sciences?

    Request to cooperate in a science project

  • How can I know the type of charge transfer using HOMO and LUMO?

    can I know the type of charge transfer either it is MLCT , LMTC or any other type  by using the type of transition inside the complex which was calculated using TD-DFT?

    in other words ... if I know that the transition is from HOMO to LUMO in the complex can I tell the type of charge transfer? how ??

    BASANT ALI HASSAN WALI-ELDEEN ALI · Alexandria University


  • Shiuli Pujari-Palmer asked a question in Purchasing:
    I am looking for the Ultrabind US 450 membrane (Pall). I was wondering if anyone had any information on how to obtain these membranes?

    I have tried contacting the company who used to produce these membranes, but they are discontinued now so if anyone had any membranes that they are not using, I would very much be interested in purchasing them. Thank you!

  • Senthilvel Vasudevan added an answer in Ethnicity:
    How do I properly run binary logistic regression with coded categorical variables?

    I have a dataset of 10k participants and am running a binary logistic regression where the dv is whether or not one endorses a particular d/o (i'm running several analyses). Endorsement of a disorder is coded in spss as 1 and non-endorsement is coded as 5 (I was given the dataset like this). SPSS automatically converts the endorsement to 0 and the non-endorsement to 1.

    The IV's I am running include: a scale iv (number of types of trauma one has been exposed to - anywhere between 0 and 19), and two nominal iv's (gender- coded in the dataset as 0=male and 1=female; ethnic/racial background- coded in dataset as 0=Caucasian and 1=Ethnic/racial minority).

    My major questions are:

    1. In the binary logistic regression box, do I mark gender and ethnicity as categorical variables if they are already coded in a binary fashion?

    2. Should I recode the DV to read 0=not endorsed, and 1=endorsed d/o? Currently, the model overwhelmingly predicts when one will NOT endorse a d/o.

    Please help! Thanks!

    Senthilvel Vasudevan · King Saud bin Abdulaziz University for Health Sciences


    Yes your coding is very appropriate.  All the best for you.

    After coding, you have do the analysis as per instructions.  In that, one important point is

    1.  Choose the Hosmer and Lemeshow test,

    2.  The value of Chi-Square value would be > 0.05.  Then only your variables are good to fit the required Binary Logistic Regression model.

    3. 95% Confidence Interval, and based on this you have to defend your odds ratio value.


    With regards. 

  • What should I do when influence points or outliers are found in regression models?

    It is easy to find methods to detect outliers and influential points in regression models. When detected what to do with them? We welcome some references.

    James R Knaub · N/A

    Jorge -

    I was once told that in "modern quality control," it is far better to expend effort to collect data well from the beginning than to try to 'fix' it later.  That would certainly seem to apply to 'outliers' caused by unacceptable nonsampling error, such as measurement error.  I too would not like throwing out data just because I assumed it was of unacceptable quality/reliability, as that is a slippery slope.  We should also be careful to define an outlier as a point that does not really belong to the population of interest, not just that it is inconvenient.

    In work I did for many years, in establishment survey sampling for continuous data, linear regression through the origin was usually most appropriate.  Substantial heteroscedasticity is naturally present, and thus weighted least squares regression is appropriate.  In such a case, rather than the usual influence points where it makes sense to have an intercept term, the most 'influential' points, in there own way, are points near the origin, which have the larger regression weights.  The estimated variances of the prediction errors are particularly at risk of being greatly overestimated by the relatively inflated residuals that commonly occur for smaller establishments who are not as sophisticated at reporting data (ie, the 'ma and pa' shops).  This can also influence slopes as well, but variance is particularly vulnerable. Thus it is generally better to use the classical ratio estimator (CRE), even though heteroscedasticity in such a situation is generally greater than that inherent to the CRE. 

    Thus the CRE is robust in a reasonable way. It allows for the fact that y predictions in general have greater relative measurement error for smaller x values, which partially counters the natural heteroscedasticity. (I say 'natural' heteroscedasticity, because one would not expect a number a hundred times larger than another to have the same variance.) 

    This then, weighted least squares (WLS) regression, is what I consider to be an interesting, and often useful corollary, to the usual considerations of influence and outliers when discussing OLS regression, particularly with an intercept term.

    The paper at the attached link provides more information.

    Cheers - Jim 

  • Anyone can explain the data in the attached file?

    I received the result of measuring specific surface area (SSA) for a clay fraction soil sample. This sample (size < 2 micron m) contain about 85 % smectite, 10% kaolinite, and 5 % illite. The CO2 gas was used in this measurement. Although the sample is rich in smectite the measured SSA was about 46 m2/g. Is this SSA value reasonable? and is this value resemble the external, internal, or total surface area?

    Behzad Shiroud Heidari · University of Tehran

    Very good comments from Dr.Celzard.

    I should add that you can measure micropore surface area by an proper method (like alpha plot and t-plot) and then compare the results with the total surface area measured in a high point of the isotherm, i.e. p/po around 0.99.

    Furthermore, you can use the attached article for more information.

    Best wishes


  • Durga Sapkota asked a question in Anisotropy:
    Is anisotropy in absorption exhibit in bulk structure? if possible what causes anisotropy?

    Masamichi Yamanishi, Hongen Shen

  • Tatyana V. Tishko added an answer in Iraq:
    Have you considered the cultural heritage an important to countries? Is there a right to anyone for destruction of cultural heritage deliberately?

    Many countries contain cultural heritage dating back to a thousand years. And thousandth of tourists visit them annually.  In recent years, it emerged organizations calling for the destruction the historic monuments. Taliban organization destroyed historic monuments in Afghanistan.  The destruction of cultural heritage has been conducted by the Islamic State of Iraq and ash-Sham (ISIS) since 2014 in Iraq, Syria, and Libya

    ISIS occupies parts of Iraq and Syria. The militant group ISIS has been destroying the artistic and religious heritage of Iraq and Syria  with a different ways including bombing deliberately, especially in Mosul, northern Iraq.

     I have a set of queries and I'd like to hear your opinion out.

    1. Are cultural heritage necessary in the lives of nations and countries?

    2.  Are cultural heritage contributing in preserve the character of countries?

    3.  Is the cultural heritage giving moral motive for the countries progress?

    4. Is historic monuments effect in the peace of the country?

    5.  What are the objectives the destruction of cultural heritage?

    6. What are the results of the destruction of those cultural heritages?

    Tatyana V. Tishko · V. N. Karazin Kharkiv National University

    Dear Qasim,

    I think that destrution of historical heritate is the attempt to destruct the historical truth. And this will give only negative results in all spects.

  • Ftema W Aldbea added an answer in Sol-Gel Synthesis:
    What would be the change in stirring time if I increase the volume of solution in sol-gel synthesis according to the stoichiometric calculations?

    i did the experiment with 100 ml of solution,after all the process ,it gave a clear solution.but the same experiment was done with same stirring time but increased the volume to 400 ml but the solution was saturated one

    Ftema W Aldbea · National University of Malaysia

    I agree with Kerem , there are other parameters led to clear solution along with stirring time. However, 100 ml  is suitable to dissolve the powder amount   at stirring rate that you used. (the ratio of solvent to the powder is not given here).

    again. look at the mechanism of the reaction.