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

  • Vinod Kumar added an answer in Bacterial Cells:
    How can I prepare Bacterial cell pellet for TEM observations?

    Can you brief a method for pre-preparation of  bacteria pellets for TEM analysis. And if I use isolated membrane vesicles for the same observation, can I apply the same method ?

    And is this cell preparation method suitable for SEM analysis also?

    Vinod Kumar

    You can also see the below attached file.Definitely,it will be helpful for your need.

  • Joana Ribeiro asked a question in Urinary Tract:
    What is the current best animal model of congenital urinary tract obstruction?

    Hi I've been reading some paper and I always find different models being used and none of them ideal.

    Can someone tell me if there is a current model that is the best one known or the one that is more communally used as a model as congenital urinary track obstruction? 

    Any suggestions of papers where I can get a better idea of the models that are out there?

    Many thanks

    Joana Ribeiro 

  • Sumith Sreedhar asked a question in Beds:
    How can I develop an equation for soil tool interraction?

    I want to develop an equation for the resisting force offered to the tool, when a tool is moving through the soil bed

  • Biswanath Chowdhury added an answer in TGA:
    Is it possible for any middle exons of a gene to start with ATG or end with TAG/TAA/TGA

    Is it possible for any middle exons of a gene to start with ATG or end with TAG/TAA/TGA ? Shouldn't it behave as start or stop codon?

    I think that TAG / TAA / TGA / ATG might be present at any position along with the start and end positions of a gene. But can it be present at start / stop of any middle exons? 

    Suppose a middle exon contains following nucleotide sequence.

    Case 1 : ATGaacggattat

    Case 2 : aataacggatTAG / aataacggatTGA / aataacggatTAA

    Are the above cases possible? Please help and if possible provide me with examples/links of such exons/genes present.

    Biswanath Chowdhury

    yes it is possible that start and stop codon may present within exons but if we see that very carefully then we will see that stop codon is not present within the same frame of the transcript (joining off all coding part of a nucleotide). If we proceed by reading three nucleotides (codon) at a time then the stop codon must not present in that frame.


    If you consider the above example then you can see the stop codon is not present in the same frame from where the coding region is started.

  • Farooq Khan asked a question in Systemic Functional Linguistics:
    How can we do systemic functional linguistic analysis of texts?

    I need a practical introduction on the specified topics for my research and teaching activities.

  • András Bozsik added an answer in Science Journalism:
    Why most of the Arab scientific journals does not have the impact factor?

    It is noted that most of the Arab scientific journals does not have the impact factor despite being issued a long time ago as well as the most do not have a website. I consider this is due to the lack of scientific awareness to one of the important scientific sobriety standards.

    András Bozsik

    Dear All,

    Artur may be right. This can be a question of market value which is not equivalent with the real value. Most people try to show their brain goods in well-tried or convertible markets – journals. Another approach may be the services of processing of a journal.

    In Hungary, many Americans prefer Mc’Donalds, Kentucky Fried Chicken, Pizza Hut etc. and do not dare to taste local food.

  • Tanmoyita Nayak asked a question in Blots:
    Why there is nothing in Loading control but Protein specific signal at the right size?

    Running a 10-20% Tris-Tricine blot with nuclear and cytoplasmic fraction of cell lines transfected with 4 different expression constructs.

    Got desired protein bands (9 kd) for two constructs in right size with protein specific antibody but strangely no bands found for loading control either in cyto or nuclear fraction but found bands for tubulin and Lamin B for the other two expression constructs .

    How I am getting nice bands for the protein of my interest but nothing in the control lane?

    What could be the explanation for this situation or what should I change?

    I followed the abcam nuclear fraction protocol.

  • Paul Hodge added an answer in Autodesk:
    Does anyone have tutorials or notes for Autodesk Alias?
    I am doing practice on Alias and I have no relevant texts or notes for it.
    Paul Hodge

    Hi, I don't use Alias, but do use other Autodesk software and know there are tons of tutorials on YouTube, forums, blogs or if you pay for Lynda.com, Digital Tutors and so on. Autodesk products usually have a whole learning curve of tutorials in the menu. Autodesk would be a great place to start - unless your after doing something unusual - just go here: http://knowledge.autodesk.com/support/alias-products/learn-explore#?sort=score

    Hope this helps.

  • Verónica Albrecht-Borth added an answer in Soil Science:
    Anyone familiar with measuring nitrate directly in soil?

    Hello I am looking for a system to measure nitrate directly in soil. I found ISE but these also look like to need some kind of extraction. Are there any electrodes to put in the soil and immediately determine the nitrate concentration? Thanks

    Verónica Albrecht-Borth

    thanks a lot to everyone!

  • Michael Päch added an answer in Metal Complexes:
    What is the characterization used for finding oxidation state of Sn metal in complexes????

    i have synthesized organotin complexes and characterized by NMR, IR.

    Michael Päch

    One way to go would be 119mSn-Mößbauer spectroscopy.

    Ref.: pubs.acs.org/doi/pdf/10.1021/ic50078a043 (inter alia)

  • Federica Schiavi added an answer in Silicate:
    Can we make crystallization for silicates ?

    Can I make crystallization for powder silicates??

    Federica Schiavi

    Sure, you can. Mix reagent-grade oxides (and carbonates) in the right proportions for your target silicate glass composition. Grind these powders together, and then melt them into a homogeneous glass at a temperature higher than the liquidus temperature. You can carry out crystallization experiments using different high-temperature experimental techniques. There is a vast literature on this topic. When you cool the glass from high-temperature, crystals with various composition will grow: their size, shape, proportions will depend on the cooling rate, the cooling path, starting glass composition, temperature, pressure, oxygen fugacity ..... Good luck!

  • David Castells-Quintana added an answer in Economic Modeling:
    How to test the overidentifying in a simultaneous equations model?

    Does anyone know how to compute a test of over-identifying in a system of simultaneous equations? Sargan and Hansen tests are just used for a single equation but I need the test for the whole system of many simultaneous equations. I think there is a Hansen-Sargan test for this but I did not find any explicit reference exposing the formula.

    David Castells-Quintana


  • Ramesh Adep added an answer in MODIS:
    What MODIS data product can be used for detecting water in riparian area?

    I am working on Variable Source Areas. What the indices available to detect water from MODIS data?

    Ramesh Adep

    thank you..Mr. Ram C.

  • John Clarkson added an answer in Frequency Modulation:
    Is it possible to get anywhere pulse raman with time discrimination of fluorescence?

    Elimination of fluorescent background could be made in 4 ways- 1) frequency modulation 2) CARS 3) NIR exitation 4) picosecond pulse and time discrimination of fluorescence. 3-rd way is most reliably realized, but not always usable. At present femto second lasers and detection technique is availabe.  Is it possible to find anywhere 4th way realized solutions which could be received commercially?

    John Clarkson

    Timegate Instruments: http://www.timegate.fi/

    LinkedIn: https://www.linkedin.com/company/timegate-instruments-ltd-

  • Jacek Gryglewicz added an answer in SiO2:
    Etching of SiO2 in BHF?

    Is it OK to etch the wet oxidation deposited SiO2 in BHF solution? Will that have effects on the device performance? I am planning to fabricate FETs based on 2D layered materials (Mos2, WS2). The desired thickness of SiO2 was 300 nm, but the obtained thickness is about 330 nm. If anyone has done so, what could be the roughness difference in the as deposited and the etched SiO2? Please suggest me on this.

    Jacek Gryglewicz

    Thomass Popp you are right! SiO2 exposed to BHF is really smooth. As far as I remember there are tho commonly used concentration of BHF (7:1 and 10:1). Check this out. The only thing you should consider during fabrication of FET is very gentle slope of etched SiO2 layer (which was previously masked). I etched layers with total thickness of 230nm and obtained very long slope (about 800 nm long) while thickness was only 230 nm.

  • Henric Lassesson added an answer in Waste Management:
    What are the biggest waste management challenges in solar PV cell production?

    I'm trying to find some more information on current and emerging waste management processes in Solar PV cell production beyond dealing with Acid Waste Neutralization and the minimization of silicon dust through more efficient saws. I'm having a hard time finding reliable sources of information on different processes and the challenges or opportunities they present to the industry. 

    Henric Lassesson

    Are we just talking about silicon solar cells here or are you also interested in other types of solar cells? If you are interested in waste management of CIGS based solar cells then I suggest you go through some of these publications, from a colleague of mine.

  • Veronika Samotskaya asked a question in Recording:
    Does anybody have song recordings of African Reed Warblers (Acrocephalus baeticatus)?

    I am searching for good song recordings of African Reed Warblers. The longer the better. Or maybe somebody works near the habitat of these birds and it's not a big deal to record several minutes for me :)

    There are some recordings on xeno-canto.org, but they are way too short for the analysis :(

  • Aliaksei Z Holik added an answer in QIAGEN:
    How to increase concentration of RNA and why do the ration of A260/A230 is low and how to overcome them?

    Dear fellow researchers,

    I am working on rat brain tissues. I need to extract RNA from here. The recommended RNA concentration is >150ng/ul (reading from Qubit). I am using Qiagen products and strictly adhere to their methods.

    Aliaksei Z Holik

    As an independent endorsement, I've stopped using the Qiagen RNA extraction kit years ago. I much prefer the following kit from Norgen Biotek:


    It works just as well in terms of the yield / purity, but it doesn't involve any form of Phenol (including Trizol), the protocol is very fast and straightforward and it's about half the price of the Qiagen kit. I understand that you might be reluctant to change the kit/protocol mid-experiment. But I would recommend keeping it in mind for the future. As I said, I have no relationship to the company. I just really like their product...

  • Zoheir Damanhouri added an answer in Cytochrome P450:
    What is the simplified assay method for Cytochrome P450?

    I'm working on the impact of water pollution on the physiological and histopathological responses of Nile tilapia.

    Zoheir Damanhouri

    I am using the spectral method as shown exactly in the attached reference by Christian and it worked very well.



  • Abhiram Sarvabotla asked a question in Zeolites:
    How to Find Volumetric Capacity of Zeolites for Storing Hydrogen ?
    1. Experimental Set up 
    2. Step by step Process 
    3. Equipments needed 
    For Metal Hydrides 

    Thanks in advance 

  • Tapan Chatterji added an answer in Crystal Structure:
    Do different crystalline materials with the same structure present peaks in the same regions of a Raman spectrum?

    If two different crystalline materials present the same crystal structure, is it possible for them to present peaks in the exact same region of a Raman spectrum, or even if they present the same crystal structure, they will present different "fingerprints" in the Raman spectrum?

    Tapan Chatterji

    Different materials with the same crystal structure are likely to give similar spectra albeit somewhat shifted. The real frequency values will depend on the zone centre phonon modes. The phonon modes of different substances even with same crystal structures can be different due to the difference in strength of bonds and atomic masses. So you can get very similar spectra but frequently this will be not the case.

  • Fernando Sousa added an answer in Leadership:
    Is there any questionnaire about women leadership?

    other than LBDQ

    Fernando Sousa

    See one I built, using Kelly's Grids

  • Arun K A added an answer in Filters:
    Can anyone help me to make a elliptical or Cauer Filter (LC Filter)?

    i want to make a Cauer Filter using LC circuit. i mean i want both High pass and Low pass filters. Someone please help me to design those kind of filters.

    i dont have a cut to cut requirement,but i want to make one.

    Also i need the basic implementations of chebyshev or butterworth etc.

    Thanks in Advance



    Arun K A


    but when i used another tool to design the filters (in http://www.analog.com/designtools/en/filterwizard/#/type) they shown some LCR components in filters. thats why i asked you.

    (and your link in the last post is not working please check it)



  • Nazir Hussain added an answer in Soil Fertility:
    How can we proceed for decision on soil resource-based cropping sequence?

    Development of soil resource inventory of a given area , is considered highly imperative to take decisions on the options about the suitability of different crops in a farming system mode. At the same time, the information on edaphological requirements of different crops , is equally paramount , so that both are super-imposed in such a way, to delineate soil-crop analogues. This will pave the way for better land utilization efficiency. My further querries in this regard are as follows:

    * How should we develop a soil resource inventory ?. Shall we go for master soil pfofile stdies  or follow the grid- based soil sampling  coupled soil profiles to be later used for developing soil fertility variograms?. 

    * How shall we identify the soil fertility constraints of multiple nature from such soil resource inventory?.

    * What methodology , shall we adopt to identify   optimum soil requirement for different crops ?.

    * How should we identify the cropping sequence based on such soil resource inventory?.

    * Whether cropping sequence and land utilization efficiency are inter-related ?.If so , in what way?.

    I request my esteemed colleagues to share their experiences on these issues. Regards

    Nazir Hussain

    Yes, no one can negate the facts stated by Dr. Anoop and Dr. Rao. Even some temporary factors can change the cropping systems of an area, may be even for a limited time. Dr. Rao gave example of Rice-wheat cropping system in Indo-Pak alluvial soils. Yes, besides other factors, the eating habits of people force them to sustain  this cropping system though it is not so much economical because they want to eat their own rice and wheat while cash crops like cotton are easy to change.

  • Yuan-Yeu Yau added an answer in DNA Polymerase:
    How can you check if the DNA template used for PCR was contaminated or not?

    The PCR outcome turned out negative and two reasons were suggested:

    1. DNA polymerase used was expired

    2. DNA template was contaminated

    is there a possible experiment to confirm these two hypotheses?

    Yuan-Yeu Yau

    1. For the "2. DNA template was contaminated" whoever suggested, he/she probably meant that the DNA sample has contaminants which inhibit PCR amplification. For this, dilute DNA samples you might improve the situation.

    2. Double-check the Ta (annealing temperature) you set for PCR, and also consider add some PCR additives or GC-rich PCR buffer in case that your temperate is GC-rich.

  • Ana Maria Anselmo added an answer in Fungal Biomass:
    What are the methods used for the preparation of fungal biomass for biodegradation studies?

    I would like to prepare filamentous fungal biomass (Fusarium solani) to get a mycelium for biodegradation experiment. If anybody suggest me, would be useful.

    Thanks in advance

    Ana Maria Anselmo

    you can contact me of course my email is anaanselmo55@gmail.com

  • Hemant Kumar Singh added an answer in Rocks:
    How study of mechanical behavior of rock joints help to society?

    How the study of mechanical behaviors of rock joints help to society?

    I am looking for reliable answer whether this study help to society or not!!

    Hemant Kumar Singh

    Thanks everyone for valuable suggestion and valuable answer!! 

  • Alana Burns added an answer in Clinical Microbiology:
    Have you ever encountered thread-like structures with this morphology in your cell cultures?

    For a long time I've been struggling with what to me looks like some sort of fungal contamination in my cultures of primary porcine bronchial epithelial cells. As you can see in the pictures, it looks like a large number of very long and very, very thin threads and they are floating quite far above the cell monolayer. At some places they aggregate to form larger bundles.

    I've tried washing the cells thoroughly with PBS and add fresh medium and after 1-2 days the threads come back, suggesting that this is some kind of organism. I sent a flask containing these threads to a clinical microbiology lab. They cultured for fungi and bacteria and their reply was "no growth".

    However, an interesting observation is that the growth of these threads seems to be dependent on the presence of the cells. They do not increase in number when cells are absent.

    I have done a lot of troubleshooting and I have ruled out PBS, medium, serum, PureCol (for collagen coating of the flasks) and the laminar flow hood, as well as the plastic I'm using.

    I've done several separate cell isolations from a number of porcine lungs and pretty much every time these very thin threads show up in my cultures, sometimes a lot and sometimes not that much. I'm starting to suspect that the source is the tissue itself and that this can't be avoided.

    Has anyone ever seen threads with this morphology in their cell cultures? Any suggestions on how I could get around this problem?

    Would be very thankful for all input and suggestions since this has become quite frustrating.

    + 3 more attachments

    Alana Burns

    Glad you are managing to rule a few things out. If it is fungi it should grow without the cell layer beneath; transfer the media with thread like structures into a new flask and culture to see if anything grows out. If there is no change it would be conclusive that it is from the cell themselves and not another microorganism. You are correct in saying that you cannot see mycoplasma. We test our cells regularly for mycoplasma and it can affect cell growth and wellbeing which isn't the case here. 

    Maybe you should consider a better prep for the epithelial cells as you may have cultured mostly goblet cells. 

    Here is an EM picture of mucins; althougth this is very high magnification these strctures could like what you have in your flask at 20x. http://www.nature.com/mi/journal/v6/n2/fig_tab/mi201281f4.html

    Futheremore here: http://www.nature.com/nmeth/journal/v10/n8/fig_tab/nmeth.2523_F1.html in figure 1C there is a picture of ECM (extracellular matrices in cluture).

    Hope this helps,


  • Ali Alhayany asked a question in Kiwifruit:
    Are there any mean to separate male plants from female one in kiwifruit seedlings one year old in the field?

    I grow Kiwi fruit seedlings from seeds and i know that it  too hard to characterize the male plants from female one in the field