Q&A

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

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  • Does anyone know a good and free online database of IR spectra?
    I need to assign some FT-IR spectra of my compounds (small organic) in terms of their vibration modes. I have a couple of books but I'd like to also have a look at online resources as well.
    Javad Frounchi · University of Tabriz

    Dear all

    I am looking for infrared  molar absorptivity coefficients of the following compounds:

    succinimide, maleimide, glutarimide, caprolactam, 2-Pyrrolidinone, Anthracene, Indole.

    Does anyone know any websites or book for this  kind of data.

    Kindly please help me.

    Thank you

  • Eric B. Brennan asked a question in Soil Improvement:
    Are legume-cereal cover mixtures a good fit (i.e. well suited) for organic vegetable production?

    Legume-cereal cover crop mixes are often promoted because they combine the ability of legumes to add atmospheric nitrogen to the system through biological fixation in root nodules, and the ability of the cereals to scavenge nitrogen that is prone to leaching during the winter. Efficient nitrogen use is especially pertinent in organic systems because the cost per unit of nitrogen in organic fertilizers is relatively high. Cover crops can provide important ecosystem services (soil improvement, nutrient cycling, weed suppression, etc.) and therefore are crucial in sustainable agriculture. An important question to ask is whether or not legume-cereal mixtures are a good fit in tillage-intensive organic vegetable production systems that are common in California? I addressed this question in a presentation at the 2014 American Society of Agronomy conference based on my experience with short-term and long-term research on organic vegetable studies conducted in the major region for high-value vegetable production in California. This research has shown that the performance (i.e., biomass production, ground cover, weed suppression, potential nitrogen fixation) of cover crop mixtures can vary markedly between and within farms based on soil type, land history, cover crop management (i.e., seeding rate, planting method, planting date, mixture composition), and climate (i.e., winter rainfall and temperature).  I'd love to hear what other researchers think about the complexity of integrating these mixtures into vegetable production systems. 

  • Nadia Storm added an answer in Conventional PCR:
    Can anyone recommend a good conventional PCR protocol for dengue virus?

    I am looking for a dengue-specific PCR protocol that is known to work well.

    Nadia Storm · National Institute for Communicable Diseases

    Great, thank you so much!

  • Can anyone suggest a possible research topic?

    Can anyone suggest a possible research topic for a pregnant Nigerian population undergoing obstetrics ultrasound?

    Victor C. Kok · Asia University

    "A cohort (longitudinal) study of pregnant Nigerian women who have or have not undergone obstetrics ultrasound follow-up: the outcome for mothers and newborns".

  • Ramachandran Manickam asked a question 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

  • What is the most important muscle to resistance exercise in rats?

    In the context of ladder training.

    Hi Mohsen Javidi

    Well I can't say if the attached papers and link are good/bad because the subject does not fit with my interest field, please check them.
    With my best regards

  • How do I depolymerize natural rubber latex?

    I am working on functionalization of natural rubber latex. I found out that it was difficult to functionalize high molecular weight polymer chain. Some recommended to depolymerize or cut NR chain. May I ask for recommendation of paper that report about method to do this?

    Ali Ibrahim Al-Mosawi · Free Consultation

    https://www.researchgate.net/publication/232821426_Depolymerization_of_Natural_Rubber_Latex_Using_Phenylhydrazine-FeCl2_System

    http://www.scielo.br/pdf/po/2013nahead/aop_polimeros1249.pdf

  • Abbas Ali Amini added an answer in Lymphocytes:
    How long can I preserve WBCs (living) in RPMI media?

    I want to keep WBCs (usually 2 to 3 days after collection).

    After separation, cells were kept by mixing with RPMI, then the mixture was kept at 4°C.

    After one day, all cells were dead. Normally, I use Histoprep (lymphocytes separation media) to separate WBCs from whole blood.

    Abbas Ali Amini · Mashhad University of Medical Sciences

    I think it's better to keep them in serum in 4 degree. but 2-3 days is too long for RPMI. what do you want to do with WBCs? the answer will depend on it.

  • What is the biggest scientific coincidence that you know?
    For me the two more important are:

    1. The phase transition liquid-solid for the water is that the solid state is less dense.
    2. The dielectric screening in metals is such that the Coulomb interaction among the electrons falls at a distance of the Bohr radius.

    The first one has many important applications as the one of allowing the live in rivers during winter or so on. On the other hand, there are also very interesting electric and thermodynamic phase transitions for this material

    The second, thanks to have a so local electric interaction it allows to have almost free electrons at quite high electronic density in matter and therefore to apply theories so useful as the bands in solids. Over all in metals
    Robin Spivey · Bangor University

    Dear Daniel,

    I have a dim recollection that I too may be suffering from memory difficulties. That is why it is helpful to refresh the neural circuitry once in a while!

    One thing to beware with standardised cross-sections is that they are usually calculated by high energy physicists who are only interested in high energy physics. The ultrarelativistic limit is of course inappropriate in our present discussions because the rest mass can easily dominate the energy.

    In a way I am trying to close the gap between our understanding of the universe and the understanding that civilisations elsewhere may have. This I feel is absolutely necessary if we want to be able to comprehend why such civilisations, who may be technologically and scientifically millions of years more advanced than ourselves, would have a policy of not attempting to contact us. This is a wide gap which is why there is a need to explore what might seem to us to be rather new branches of physics.

    You asked about how the haloes are formed. We have been recently discussing this in terms of the decay of dark energy and the potential involvement of (pseudo) black holes. I am leaning towards the explanation that collapse to a black hole only occurs when a system runs low on energy. Matter is never quite compressed sufficiently for an event horizon to appear but as the collapse is asymptotically frozen by gravity (within the framework of general relativity) kinetic energy is lost and the collapsed structure increasingly resembles an object of zero energy density. I argue that this then provides a target onto which dark energy can decay, with its energy flowing into the universe as the (pseudo) black holes become (pseudo) white holes. I suggest this energy could well take the form of neutrinos, perhaps due to the involvement of the electroweak interaction during the decay. The neutrinos may locally appear to be relativistic but as they escape the white holes they become nonrelativistic or at least very low energy.

    Most of the neutrinos would come from supermassive former black holes, or supermassive white holes. Due to having little kinetic energy and being trapped within the gravitational potential of a surrounding galaxy, they are sure to cluster. But, being fermions, degeneracy pressure ensures they maintain their distance from one another. The density I mentioned, some 10-24 km/m3 is the minimal density at which liquid oceans can be sustained (assuming a neutrino mass of 0.05eV). However, this density can be increased about three orders of magnitude before there is a risk of the halo becoming so dense that gravitational implosion occurs (see equations 11-17 of my paper).

    Intuition can be slightly misleading here because we know that neutron stars are heavier than white dwarves and neutrons are heavier than electrons. But white dwarves are not just a gas of electrons, there are heavy atomic nuclei adding considerably to the gravitating mass. Reduce the neutron mass and the maximum mass of a neutron star increases. Reduce the neutron mass all the way down to the mass of a neutrino and the maximum mass becomes gigantic, something like 1021 solar masses! In yet another happy coincidence, a neutrino halo of this mass is large enough to accommodate the biggest galaxy.

  • Why are people (dis)honest?

    "Rooted in the philosophies of Thomas Hobbes, Adam Smith, and the standard economic model of rational and selfish human behavior (i.e., homo economicus) is the belief that people carry out dishonest acts consciously and deliberatively by trading off the expected external benefits and costs of the dishonest act (Allingham and Sandmo 1972; Becker 1968). According to this perspective, people reach a decision that maximizes their interests and are honest or dishonest only to the extent that the planned trade-off favors a particular action (Hechter 1990; Lewicki 1984).

    From the "The Dishonesty of Honest People" one of the most cited article (see)

    http://people.duke.edu/~dandan/Papers/PI/Dishonest_JMR.pdf

    I am interested to know your opinion about

    Huajiang Ouyang · University of Liverpool

    While most people who responded here spoke of dishonesty as bad, dishonesty is good in some situations.

    When a student asks me what I think of him, I do not give him a complete honest opinion. An honest one can hurt and would not help. If my leader asked the same question, I would not venture a very honest one. Who would?

    Sometimes a doctor does not disclose the true extent of an illness to the patient for his/her own benefit.

  • Artur Burzynski added an answer in DNA Barcoding:
    What is the utility of DNA Barcoding in marine perspective?

    Thank you in advance for your answers.

  • Joseph Fritz Lemaire asked a question in Gamma Rays:
    What is the highest gamma ray frequency that can currently be technically detected and observed?

    High energy astrophysicsts  and Nuclear Physicists

  • How do you rate a journal as a good one?

    Different people rate scientific journals differently. Some of them rate journals on the basis of impact factor while some other put stress on the quality of research works the journal publishes in reality..... still some other people love some other methods to rate journals. What are your personal rating points?

    Joseph L Alvarez · Alpha Beta Gamut

    I judge a journal the way I judge a publication, usefulness, relevance, accuracy, content, understandable, organization, and honesty. A good journal requires each article to be a good article. Several high impact journals have abandoned one or more of these qualities to be more socially relevant and politically correct.

  • Aisha Tanvir added an answer in Graphene Oxide:
    Can anyone tell us in detail, how to synthesize graphene oxide?

    Thanks in advance for your replies.

    Aisha Tanvir · Qatar University

    There are a number of method to synthesize GO, most commonly used are hummers and tours method, previous commentators have attached references to both the methods....

    Most important thing in successfully preparing GO is maintaining the temp, good luck!

  • What is the scientific explanation for the left part of brain controlling right part of body and vice-versa?
    I don't understand why if we stimulated children's right part of body, it can make left part of brain grow rapidly.
    Ravinder Jerath · Augusta Women's Center

    The reason the brain is wired on the contralateral side is explained in my recent article published in "consciousness and Cognition " journal. This article explains why in patients who have Contralateral neglect syndrome they can not locate objects on their contralateral side even though they have no visual impairment. Moreover these patients have inability to feel the left side of their bodies . The defect is commonly associated with stroke affecting right parietal cortex.

           The explanation answers the basic question as to how we see the world. The first figure in the article shows that what we see outside actually is seen internally by our brain in the same exact way, ie the left side of our vision is imaged on the left side of our head and body. The left side of our body unconsciously positions the left side of the scene we see outside. It may be hard to imagine however all we see actually is within self. The thalamus acts like a tiny brain . All the space around it formed by all the cells of the body and visual apparatus of the brain behaves like an empty  space that I have termed "3 D Default space " . It forms the internal world that we only perceive as darkness when we close our eyes. It truly is amazing how brain perceives consciousness in this space subconsciously. 

  • Farid Fayez Youssef asked a question in Plague:
    Why when I expose hippocampal slices to ischemia is the recovery response all or nothing?

    This situation has been plaguing our lab for some time. When exposing hippocampal slices to ischemia either they recover fully or develop an injury potential and do not recover at all? 

  • What should be the basic parameters for the full classification of carbon allotropes (polymorphs, polytypes)?

    In recently published book (Shabalin IL, Ultra-High Temperature Materials - I, Springer, Dordrecht, 2014) I have suggested to apply for it so-termed "specific bond enthalpy", i.e. average bond enthalpy per C-C bond order (please see the file attached). However, it seems to me that for the intermediate carbon families (e.g. the fullerene family) it should be applied some parameters else; maybe geometrical ones, for example, the pyramidalization angle or something similar, although more likely there is some kind of correlation between the angle and bond enthalpy. Could anyone share with me their personal views on the problem? I would be also glad to get from everybody any remarks on my list of carbon allotropes (polymorphs, polytypes) as more likely some of them have not been listed yet. I believe the answers to these questions will help us to create more perfect classification of all the carbon forms experimentally observed and theoretically predicted.

    Igor L Shabalin · University of Salford

    Dear Alain, Many thanks to you!

  • Victor C. Kok added an answer in Myxoma:
    Is there any relationship between cutaneous squamous cell ca and atrial myxoma?

    Is it possible to define any relationship between cutaneous squamous cell ca and atrial myxoma? We have seen both tumors in the same patient. We haven' t seen any report about this simultaneous occurance. However there are some reports about the simultaneous occurance of the squamous cell ca of the lung and myxoma.

    Victor C. Kok · Asia University

    To my knowledge, there is unlikely a biological explanation for the association between cutaneous squamous cell carcinoma and atrial myxoma. Synchronous presentation of these 2 tumors however is of course possible!

  • What is the best way to compare two spectral data and how to quantify?
    Is there a way to compare two spectra and quantify in some way how close they are associated? I have six samples and want to study the closeness (with quantification). What is the best technique to use? Thanks in advance.
    Olivier Sire · Université de Bretagne Sud

    One cannot estimate euclidian distances between data which have been submitted to distinct preprocess .

    The golden rule: Same preprocess in the very same sequence.

  • Mohamed El Naschie added an answer in Dependability:
    How can I identify the non-conservative forces? Is there any difference between the non-conservative and dissipative forces?

    In dynamics, the position dependent forces are conservative where as the velocity and time dependent forces are non-conservative. Is there any other criteria to describe the non-conservative forces?

    Mohamed El Naschie · Alexandria University

    an example of nonconsevative force is the axial load on a canteliver which change it's direction as to remain tangential after buckling. it is called beck problem. here you can not use energy methods. friction force is the same.all energy losses ie dissipation and energy gain ie flutter is nonconcervative. i joined both so that a balance give a concervative system. i used this in structur engeneering.see my book in MC GRAWHILL  stress stability and chaos in structurl engeneering  1990 . later on i used the adjoint system method for quantum physics and 2 schroedinger equations in duality

  • How can one calculate Elastic modulus by using rule of mixture?

    How can one calculate Elastic modulus of these glass particles reinforced polymer composite samples (as mentioned in previous question ) by using rule of mixture?

    Ali Ibrahim Al-Mosawi · Free Consultation

    http://pas.ce.wsu.edu/CE537-1/Lectures/Rule%20of%20Mixtures.pdf

  • Artur Burzynski added an answer in RAPD:
    Is electrophoretic separation of non-homologous DNA fragments of the same size possible?

    I want to sequence RAPD fragment by cloning it. I don't know if my fragment of interest is homologous and it's quite possible that few non-homologous fragments of the same size migrate together. Is there a way to find out how many of them I have and how to separate fragments of the same size but different in their sequence, so I could get them all cloned and sequenced? thank you for the answers.

  • How can one compare organic and conventional farms having different cropping pattern?

    Conventional farms are in general are monocropping based whereas organic agriculture is suppose to have a more diverse cropping system and these two systems may have a different cropping cycles. Most studies compare them on basis of single crop which seems unfair to the organic systems. I want to design an experiment to systematically compare  the yields and soil parameters in these systems. Can anyone suggest studies that are present or any ideas to compare these in common unit(besides money, I don't want to use money either as they do not reflect the true value).

    Eric B. Brennan · United States Department of Agriculture

    You may be interested to see a recent presentation that Michel Cavigelli and I gave titled 'Organic versus conventional Comparisons:  A devil without details'. See YouTube link below.  Making valid comparisons can be difficult and researchers need to be very careful to provide enough details on the systems being compared to ensure that the comparisons are meaningful.  

  • Ali Ibrahim Al-Mosawi added an answer in Electron:
    What is the electron affinity of p-ZnIn2Se4?

    Hello, can anyone let me know the Electron Affinity value of p-ZnIn2Se4? or suggest a method with which it can be deduced.

    Thank You

    Dhananjay Dhruv

    Ali Ibrahim Al-Mosawi · Free Consultation

    https://www.google.iq/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCUQFjAC&url=http%3A%2F%2Fopus4.kobv.de%2Fopus4-tuberlin%2Ffiles%2F3283%2Fjanocha_eike.pdf&ei=gXSVVMeJMMT1ar2YgqgJ&usg=AFQjCNHjVuoHigEVwxcULD-JYr99QgkwkA

  • Hugh J Byrne added an answer in Raman Spectroscopy:
    How can I decrease the fluorescence of my samples for Raman spectroscopy?

     I am trying to get the Raman spectra of solutions with very low concentrations of amino acids 1mM-6 mM. However, I can not see their peaks because they are masked by the fluorescence of the solutions, which also prevents me from using long exposure times.  I have no idea what is the source of this fluorescence because my buffer is 25 mM  in Tris-HCl and 150 mM in NaCl (pH=7.2).  Also, I always wash my cuvettes with soap and nitric acid before using them. Does anyone have any tips on how to decrease the fluorescence? By the way, I am using a 514 nm laser source.

    Hugh J Byrne · Dublin Institute of Technology

    In order to produce fluorescence, the molecules must absorb at the source wavelength and then emit. I do not believe that any of your constituent components do this at 514nm. Thus, what appears to be fluorescence can be Rayleigh scattering of your source and even the Raman of your sample, which enters the spectrometer as stray light, and is registered across the detector, therefore resembling broad band fluorescence. We have studied this in protein powders and tissue samples.

    "In vitro analysis of immersed human tissues by Raman microspectroscopy",
    F. Bonnier, A.Mehmood, P. Knief, A. Meade, W. Hornebeck, H. Lambkin, K. Flynn, V. McDonagh, C. Healy,T.C. Lee, F.M. Lyng, H.J. Byrne,
    Journal of Raman Spectroscopy, 42, 888–896(2011)

    I would suggest sonicating your sample, or filtering to remove any aggregates. The use of a confocal hole can also reduce the scattering from solid samples.

  • Arno Gorgels added an answer in Unified Theories:
    What is the lifetime of the proton and how do we understand it?

    It used to be considered gospel that protons, unlike, say, neutrons, live forever, never decaying into smaller pieces. Then in the 1970's, theorists realized that their candidates for a grand unified theory, merging all the forces except gravity, implied that protons must be unstable. Wait long enough and, very occasionally, one should break down. The trick is to catch it in the act. Sitting in underground laboratories, shielded from cosmic rays and other disturbances, experimenters have whiled away the years watching large tanks of water, waiting for a proton inside one of the atoms to give up the ghost. So far the fatality rate is zero, meaning that either protons are perfectly stable or their lifetime is enormous -- an estimated billion trillion trillion years or more.

     (taken from http://www.oglethorpe.edu/faculty/~m_rulison/top10.htm)

    Arno Gorgels · Principia Naturae

    Protons exist of particles that exist in two different space-layers. This is the reason that they don't decay. But protons can be torn apart by forces of relativity. 

  • 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

    Kamaladevi Arumugam · Alagappa University

    Use primer 3...

  • What is the best antifungal used in isolation of a mix of bacteria and fungi?

    I have some environmental samples that contain both fungi and bacteria and I want to isolate only bacteria

    What is the best way to do that and if I want to add antifungal in the media, what is the best and what is its optimum concentration?

    I will be thankful, if help with papers.

    Best Regards 

    Muthamil Iniyan · Manonmaniam Sundaranar University

    Nystatin would give you a good results. We are using this for actinomycetes isolation. Cycloeximide is banned you may not get this.

  • What is the lowest surface tension possible with water?

    Which is the best way to decrease the surface tension? Surfactant or boiling?

    Is contact angle same in same surface tension of soap water and boiling water solutions?

    Alexander J. Babchin · Tel Aviv University

    Boiling does not reduce surface tansion of water drastically, as boiling at 100 C is far away from the critical point, were surface tension is zero. Surfactants are capable to reduce surface tension drastically. Foam bubbles separating from bulk water is the shining example. Surfactants not only reduce surface tention, but induce disjoinng pressure between the surfaces, keeping either foam or a colloidal sytem stable. The mechanism is described in the paper attached.

  • Diogo Santos asked a question in Normal Distribution:
    How can I calculate the best distribution for a model with underling features?

    In my model W = f(E, K). f is a complex function (several operations on E and K).

    f' > 0, but for any W, infinity pairs of (E, K) exist that satisfy f.

    E and K are between [0, +oo]

    I have observations for W and I had estimated from other sources the distribution of E.

    I suspect that K is a mixture distribution between a discrete function (K=0) and a mixture of normals distributions.

    How can I calculate the most likely distribution for K (taking into account some penalty for adding more normal distributions in the mixture)?