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  • Will pre-treating petri dishes with collagen or gelatin affect HUVEC gene expression?

    I'm trying to interface between two phases of a project - the first set of transcriptomic measurements were collected from cells plated on dishes that were not pre-treated. The next phase involves gene knockdown protocols that suggest pre-treating petri dishes with collagen. I want to make sure that the protocols implemented in the second phase of the project are biologically consistent/relevant to the experiments from the first phase. 

    It's reasonable to assume that pre-treating with collagen will have an impact - I'm curious as to how significant that impact may be...Does anyone have any experience testing the effect of pre-treating petri-dishes with collagen/gelatin on HUVEC biology (primarily, gene expression)? 

    Thank you!

  • Jean Rene Grezes added an answer in Organic Dyes:
    What is the range of pi-pi* and Intramolecular charge transfer bands in absorption of a dye?

    I wanted to know the range of pi-pi* and intramolecular charge transfer bands in the absorption spectrum of an organic dye (donor-spacer-acceptor).

    Jean Rene Grezes · Laboratoire Prive

    Dear Sai,

    when you write:

    I wanted to know the range of pi-pi* and intramolecular charge transfer bands in the absorption spectrum of an organic dye (donor-spacer-acceptor).

    It is too vague! Organic dye ! What a kind?

    Please give more infos about your dye (DSSC)  and spacer  (-CH2-  or rigid   like          R------R  a.s.o...).

    About DSSC :    Please read this link :


    Note :

    answerers cannot give good answers without joined infos   (jpg or pdf...) in the question.


  • Akilesh Ramasamy added an answer in Software:
    What is the most important consideration in the initial planning of software solutions(or packages) development?

    * Example solution : healthcare solution(eg. EHR,EMR), financial solution, EPM Solution,...

    Akilesh Ramasamy · Consultant Oral and Maxillofacial Surgeon
    1. Assess the need for a new software (who needs it and why?)
    2. Design UI (front end should be userfriendly)
    3. Robust Back end that should be flexible and permit scaling and it should be interoperable with other platforms / analytics
    4. Permit analytics
    5. Involvement of the persons who will be using the software platform mostly (so if you are developing a customised EHR in a hospital, it should get the involvement of the physicians and nurses along with the front desk people who will use it mostly)
    6. Regulatory compliance and secure.
    7. Privacy
    8. Cuts down on the user's time infront of the screen and increases the time spent in the actual task. 
  • Shane McGee McMahon added an answer in P Value:
    Statistical importance of the P value questioned!! What are the alternatives in biological research?

    Following are the links and a file for questioning the statistical importance of the P value and its interpretation in biological research. What will be forthcoming alternatives?

    Shane McGee McMahon · University of Wisconsin–Madison

    I generally agree Jochen and the majority here that the main problem is a lack of adequate training, which would suggest that increased training would be a more reasonable solution than banning p-values.

    However, I think that there is a flaw that is somewhat specific to p-values and is not shared by other approaches, say bayesian methods. In particular, it seems quite easy for a scientist to interpret a p-value as the probability that the null hypothesis is true given the data, and believe that they understand what they are doing. But, that same scientist may at least understand that they do not understand bayesian methods.

  • Josh Robertson asked a question in Skepticism:
    Innovative ideas on how to reduce or ideally eliminate rat populations on an island? Would ultrasonic devices repel them effectively?

    I'm currently monitoring tropicbirds on a Caribbean island and the populations are being devastated by rats and on another island cats. Does anyone have any suggestions on best removal methods other than traditional rats traps using Brodifacoum? Rat populations have become resistant to this poison and so we're looking for other controls. I thought ultrasonic rodent repellent devices may work however I don't know enough about them - I'm a little skeptical on how well the sound would travel outdoors.

    Thanks, Josh.

  • How can I measure common mode voltage in MATLAB/Simulink?

    Thanks in advance for your replies.

    Luis Ramon Merchan Villalba · Universidad de Guanajuato

    Are working with simscape?

  • Maria Vasilopoulou added an answer in Dyes:
    What are the HOMO and LUMO levels of Coumarin-500?

    I'm a graduate student researcher currently working on OLED processing using a host:guest system and I'm trying to understand which process takes place in my structure when I add coumarin-500 as a dye in my matrix. The problem is I can't find the currect energy levels of this material. Does anybody know where I can find this information?

    Maria Vasilopoulou · National Center for Scientific Research Demokritos

    Dear Daniel

    I think that the energy levels are: HOMO=5.1 eV and LUMO=3.4 eV.

    See also the manuscripts by 1) Wang et al. J. Phys. Chem. C 2008, 112, 17011–17017 and 2) Hara et al., J. Phys. Chem. B 2005, 109, 15476-15482

  • Ion C. Andronache added an answer in ImageJ:
    How do you open a GEOTiff File in imageJ?

    I am about to use imageJ for oil spill detection where I need to work with GEOTiff file format. It is written in an imageJ document that it supports GEOTiff Files too. I need to know how to open GEO Tiff as it is not opening using the simple open menu. Please help me if anyone knows about GEOTiff with imageJ.

    Ion C. Andronache · University of Bucharest

    You can use Fiji.


    I can open color or greyscale GEOTIFF without problems.

  • Is there an existing literature on intergenerational learning within the medical school curriculum or service projects?

    I am most interested in the intersections between family medicine doctors-in-training and aging patients living with dementia.

    Good. Would love to hear more about what you are doing. It's absolutely the right approach!

  • Can you suggest me a good method for collecting sweat during exercise?

    I want to measure electrolytes in sweat during training, and for the analysis we need something like 100 microliters of sweat collected in an eppendorf or probe. Thank you.

    Alex Buoite Stella · University of Udine

    Thank you Matthew.
    Olivier, I want to collect and then analyze it the day after in the laboratory. I know that somebody in pediatrics use a sort of "cups" they put on the skin after the stimulation (in our case the stimulation would be simply through exercise) and from that cups after 30 min they find the sweat and then they draw the sweat in a syringe.
    The important is that I can take to the lab 100 microliters of sweat in an eppendorf or tube.

  • What is the best storage of conditioned media (at 4C/-20C/ -80C) for subsequent isolation of exosomes?

    I wish to isolate exosomes from MSC conditioned medium and would like to know what is the appropriate temperature for storing it in case i am not proceeding with exosome isolation immediately after conditioned media collection .

    1) Can conditioned media be stored at 4C/-20C for a week prior to exosome isolation. Will it damage the exosomes or degrade the biomolecular cargo present within them.? 

    2) I am aware of the fact that conditioned media can be stored at -80C , but somehow feel uncomfortable doing the same as i think thawing conditioned media from -80 to 4C might damage exosomes resulting in poor exosome yield .

    So i need help in two things

    1) what is the best temperature (4C/-20C) for short term storage (1-2 weeks) of conditioned media that would cause minimal exosomal damage ? 

    2) if storing at -80C , what is the best procedure for thawing conditioned media without damaging exosomes..

    Thank you

    Sandrine Pizette · University of Nice-Sophia Antipolis

    I am not sure what you want to do with your prep but I keep exome prep in fixative for up to a week at 4°C before performing electron microscopy.

  • Abdul aziz Jaafar added an answer in Movements:
    Any suggestions on thrust movement with quadrotor ?


    i try to do the thrust movement but i observe that the quadrotor did a movement according to the nose direction.

    can anyone explain me this problem ?

    thank you very much

    Abdul aziz Jaafar · Universiti Malaysia Pahang

    Hi Yassine

    Can you elaborate what you mean by thrust movement.  From my understanding, for a 'physical' multirotor in hovering flight phase, if you apply additional thrust, it will translated vertically, but sometime the hardware may not perfectly synchronised, the vehicle may perform a slight yawing motion ( nose motion ).  In modelling you wont see this, as you assume the hardware that sending the control signal to each of the electric motor (as most people use) at the same time.  On practise, you need to calibrate the motor driver.. hope this help .. wallahu a'lam


  • Tomasz Kalwarczyk added an answer in Alexa Fluor:
    Where can I find the diffusion coefficient of Alexa 430 in water?

    I would like to calibrate the FCS system using Alexa 430 (for excitation laser 440). The best would be the plot for different values of room-temperature.

  • Hylton P Gordon added an answer in Catheters:
    When you need a small volume, small gauge catheter, what do you use?

    We've had good luck doing direct intraosseous injections into the tibiotarsus of small birds, but when we try to use catheters we've made out of tubing and cut-off needles, these always seem to break when we try to insert them into the bone. I can't find commercially available catheters with volumes less than 0.25 ml in the gauges we could use (25-30 gauge). Any suggestions?

    Hylton P Gordon · Icahn School of Medicine at Mount Sinai

    Have you tried a Butterfly system, obtain a butterfly cath. w/25g needle, use the needle for direct intraosseous injection; you then have the benefit of the tubing which may be connected to your fluid source. Be cautious with the infusion pressure. Unfortunately I am not aware of a commercial gadget to suit your needs in this regard. Please let me know if the butterfly works.  

  • How can the competence of undergraduate dental students be assessed?

    At undergraduate level, a dental student learns many psychomotor skills as well as the relevannt theory to practice as general dental practitioner. I would like my dental colleagues who are in teaching profession to share their views on effective assessment of dental students' comptence. 

    Adil H.H. Bashir · University of Khartoum

    Teaching is an art, building skills at the fine and young delicate  finger tips as well as raw brains, from here competence raised.  so you are impeding confidence inside him/her and from then his/her competence been built.

  • How to introduce mathematics in psychology?

    I was in a meeting and a man said samothing about that, so now I'm interested in that.

  • Ahmed Saeed Hassanien added an answer in Chalcogens:
    How can we get nano glass from chalcogen elements or their alloys?

    Bulk chalcogenide glasses are prepared by rapid cooling of the melt. How can we get the same in the form of nano glass?

    Ahmed Saeed Hassanien · Benha University

    Dear Prof. Dr Kumar 

    with my great greeting 

  • Has anybody tried electret formation on dielectric polymer films by corona discharge method?
    Can you share some information on that, like how he setup should be? What should be the voltage and current range should be used. Is there any requirement of vacuum in the chamber?
    Ankur Goswami · University of Alberta

    Thanks a lot Sebastien

  • Which filter paper is best for the sampling of particulate matter from the air for persistent organic pollutants?

    I saw in literature people were using quartz microfiber and glass microfiber filters.

    Please suggest which one is better for aerosol sampling of Persistent organic pollutants.


    Alfredo Campos · Centro de Investigación de Materiales Avanzados

    Hi, quartz its better for organics in PM. This filters have less contaminants.

  • Is Chalmers' so-called "hard problem" in consciousness real?

    In his 2014 book "Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts" Stanislas Dehaene wrote "Chalmers, a philosopher of the University of Arizona, is famous for introducing a distinction between the easy and the hard problems. The easy problem of consciousness, he argues, consists in explaining the many functions of the brain: how do we recognize a face, a word, or a landscape? How do we extract information form the senses and use it to guide our behavior? How do we generate sentences to describe what we feel?

    “Although all these questions are associated with consciousness,” Chalmers argues, “they all concern the objective mechanisms of the cognitive system, and consequently, we have every reason to expect that continued work in cognitive psychology and neuroscience will answer them. By contrast the hard problem is the “question of how physical processes in the brain give rise to subjective experience … the way things feel for the subject. When we see for example, we experience visual sensations, such as that of vivid blue. Or think of the ineffable sound of a distant oboe, the agony of an intense pain, the sparkle of happiness or the meditative quality of a moment lost in thought … It is these phenomena that poses the real mystery of the mind”."

    Stanislas Dehaene's opinion is "that Chalmers swapped the labels: it is the “easy” problem that is hard, while the “hard” problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmers’ “hard problem” will evaporate".

    Personally, I agree with Stanislas Dehaene's opinion.

    Ravinder Jerath · Augusta Women's Center

    Marc, I am answering your question below. 

    I don't understand the meaning of your expression "default 3 D space": could you clarify it for us?

    "The default 3 D space is the three dimensional space within our interapersonal space."It is where the elusive blackbox of entire consciousness resides. 

  • C. E. Larrabee added an answer in Oil:
    What would be if microemulsion water/oil/surfactant did not contain oil phase?

    For example, if the surfactant is non-ionic one, wouldn't it still form micelles in water or aqueous solution?

    C. E. Larrabee · University of Cincinnati

    Yes. The hydrophobic tails of the surfactant self assemble into an oil-like micronenvironment in the micelle core.

  • Shadab Ali Khan added an answer in Dentistry:
    What are the differences between biobloc orthotropic and the other functional appliances ?

    what are the different between biobloc orthotropic and the other functional appliances 

    Shadab Ali Khan · King Khalid University

    Old product wrapped in a new attractive wrap and marketed by smart orthodontist based on old principle of FJO

  • Samir Al Jbour asked a question in QIAGEN:
    How to reduce amount of sugar from soft Coral DNA sample?

    Today I extracted the DNA from soft coral, but it was very contaminated with sugare that is the absorbance at 230 was relatively high.

    I think it is due to Mesoglea or the mucus it produces

    I used the Qiagen kit?

  • Which method is best for Staphylococcus aureus detection and live/dead discrimination by Flow cytometry?

    Dear Researchers,

    Anybody working this area please send me the protocol/articles.

    Suzannah M Schmidt-Malan · Mayo Foundation for Medical Education and Research

    Christer, we are currently trying to run S. aureus through our flow cytometer, we stained the cells with Live/Dead (syto) but we are having a difficult time with what parameters to use for the cytometer as we have a lot of background, and cannot distinguish our cells from the background. Could you offer any insight? Thanks!

  • Nicolas L'Heureux added an answer in Cell Culture:
    Failure in cell detachment after trypsinization.
    I use trypsin to harvest my cells (NIH 3T3), but they don't detach after trypsin incubation. I tried to increase trypsin volume and incubation time in 37C incubator. I usually use 3ml of trypsin per 25cm2 T flask and incubate for 3 mins at 37C. I got a very small amount of cells and subcultured cells also don't detach from the bottom of the flask. Has anyone encountered the same problem? How did you solve it?
    Nicolas L'Heureux · Cytograft Tissue Engineering, Inc.


    If you cultured the cells with ascorbate and/or if you let them stay confluent for a long time, the problem is likely collagen related as explained by Henry.  If that's not the case, then your trypsin is probably to blame (especially if that's something that you have been doing routinely) .  As mentioned above, use a fresh batch, use it warmed, incubate warm (maybe longer) and rise well before hand ( I like to use a little trypsin to rinse). Let us know what worked!

  • How to do phylogenetic analysis from LDH isoforms?

    I'm studying about phylogenetics position from fishes to isoforms ldh-a, ldh-b e ldh-c, but I have to do bayesian analysis and likelihood and the question is...Do I have to treat the isoforms separately? Do I have to partitioned the data from each isoforms?If I have each isoforms to a species, the input data it looks like:
    ldha = 1 - 798
    ldhb = 799 - 1597
    ldhc = 1598 - 2396

    Or do I have treat the isoforms like a same unit/gene?


    Vincent Lefebvre · Muséum National d'Histoire Naturelle

    Hi Erica, I would recommend you take a look at this http://www.biomedcentral.com/1471-2148/6/99

    Basically you can try both ways, either concatenate your data into a superalignement (or into unaligned sequences if you use dynamic homology) or build separate trees based on each sequence and their consensus. The advantage of the last method is that you can use different mutation models for each sequence if it is relevant to do so.

  • Zain Dardas asked a question in Software Design:
    What is the recommended software to design a figure for protein sequence ?

    i wanna make a figure to illustrate the effect of a nonsense mutation in specific gene through the presentation of the resulting protein .

  • Daniele Sasso added an answer in Doppler Effect:
    Is the doppler effect of light an actual energy shift of photons or it is only a relativistic connection of different reference frames ?

    Some authors affirm that since the doppler effect is based on energy/momentum conservation in the laboratory frame it is an acutal energy shift of the absorbed photon. A tiny part of the kinetic energy of the absorber is transformed into the electromagnetic energy of the absorbed photon, raising its frequency. The relativistic part (LORENTZ factor) is due only to the rescaling of such energies.

    Some others reply that the above view point is not correct.  Doppler effect of light, though can be drawn from the energy-momentum conservation alone, is only a relativistic effect, a matter of seeing the same photons from different view points.

    I fully agree with the first point of view.  It is quite important according to my opinion to clarify on such distinction.

    Maybe a third view?

    I wish your opinion about it.

    Daniele Sasso · Progetto Indipendente ARS


    the relative speed between two reference frames isn't an apparent phenomenon but it is a real fact. Two inertial reference frames aren't two equivalent systems in all physical aspects, but only in relativistic aspects, because the relative speed between two reference frames implies also a different kinetic energy. Dear Stefano, I think you will become a free and independent scientist when you will free yourself from the Lorentz transformations.