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  • Michael Päch added an answer in Hexanes:
    Which is best clean up procedure for PCBs and other organochlorine compounds from sediments?

    I am extracting PAH, PCBs and other organochlorine compounds using 100%DCM. Then added 100% Hexane in it and concentrated to 1 ml. Then separated the extract in to two for both PAH and organochlorine compounds.

    I want to know is the cleaning procedure for organochlorine compounds including PCBs can be done by  96% sulfuric acid or dichromate??

    Is there any column chromatography step needed for PCBs and organochlorine compounds from the above procedure?



    Michael Päch

    @Adrianne: Did you get my point?

  • Dhanu Chettri asked a question in EMP:
    Is there any future possibility of making an EMP resistance electronic circuit?

    EMP (Electro Magnetic Pulse ) can easily fired up the modern electronic circuit in a second.can we make a circuit which is immune to EMP ? I don't mean putting an electronic items in Faraday Cage, m curious to find if we can make the circuit itself EMP resistance. If there is possibility how can we make it?

  • Stam Nicolis added an answer in Zeta Function:
    What are the current application of Riemann Zeta Function in analysis of elementary particles?

    I want to know the applications of Riemann zeta function in analysis of elementary particles and other high energy physics phenomenon.

    Stam Nicolis

    One application of the insights that the study of the properties of the  Riemann zeta function has spawned is the technique of ``zeta  function regularization'' and a review may be found here: http://library.msri.org/books/Book57/files/20kirsten.pdf . 

  • Greg Hannsgen asked a question in Differential Equations:
    Where can I find an analysis of bifurcations in the 4D vector field associated with a Jacobian with the following normal form?

    I have a system of autonomous differential equations whose dynamical behavior I wish to analyze. The matrix is {{0,-omega,0,0},{omega,0,0,0},{0,0,0,0},{0,0,0,0}}. A reference would be very helpful, or even a name for the associated bifurcations. Another case of interest would be {{0,-omega,0,0},{omega,0,0,0},{0,0,-1,0},{0,0,0,0}}

  • Lydia Katrova added an answer in Movement Analysis:
    How can I make an interdisciplinary theme understood?

    I am working on an important theme that has aspects of dentistry, neurology and movement analysis. The dentists do not read the neurological and movement aspects and the neurologists do not read the dentistry part –so since years, nobody gets the important point and it is not possible to make a study. My theme is that spatial orientation is subordinate to spatial synchronization – the synchronization, however, determines body posture, movement and may be responsible for severe pain. Synchronization is determined by the position of maxilla and its teeth. It is necessary to get all of the aspects to understand the connection. Benefit: to be able to cure therapy-resistant back pain in craniomandibular patients. What can I do to make the aspects understandable for the involved disciplines?

    + 1 more attachment

    Lydia Katrova

    Dear Ruth I am happy you found something useful in my comments. Please send your video. It is great!

    Thank you,


  • James E. McLean added an answer in Semi Structured Interviews:
    Is it justifiable, in a longitudinal study not to amend flawed questions? Why?

    I have undertaken several longitudinal studies using unstructured/semi-structured interviews and investigating the potential for using surveys.  I have identified one particular issue with surveys in longitudinal studies - would welcome some robust discussion on whether there is any justification for continuing a longitudinal study with known flawed questions that are not going to be changed.  Or, from another perspective, just how much does altering any question undermine the validity of the longitudinal study? 

    James E. McLean

    Assuming the interview/survey produces scores that are compared over time, it is permissible to modify questions if equating studies are done with the old and new items and appropriate adjustments are made.  That would require that the study be conducted at least once with both the flawed and corrected items so the differences in performance could me assessed.  If this were not done, any longitudinal comparisons  would not be entirely valid.

  • Vassiliki-Alexandra Glezakou asked a question in Environmental Applications:
    Are you going to Spring ACS 2016?

    For those interested, I am co-organizing a symposiun in the Spring ACS 2016 (COMP, PHYS), San Diego, titled "Structure, dynamics and reactivity at complex interfaces with relevance in renewable energy and environmental applications" deadlines for abstract October 12! Hope to see you there!

    Let me know if you have questions.

  • Moloud Ashtari added an answer in ANSYS:
    What are the possibility of non convergence of analysis in ansys apdl for concrete cylinder model?

    I have modeled a concrete cylinder for compression test in ansys using concrete 65 element. I have modeled and done with the linear analysis. But when I am performing nonlinear analysis by taking M30 concrete nonlinear property; the result is non converging after taking a uniform pressure of 19 Mpa. At the last sub step after 19 Mpa pressure load the displacement is very high. Can anyone help me regarding this issue? I have attached my ansys apdl script file for reference.

  • Bruce Weaver added an answer in Syntax:
    Help to run contrasts in SPSS syntax: in the syntax below I wrote the contrast line but it doesn't work so any ideas about why?

    GLM var1 var2 var3 var4
    /WSFACTOR=conditions (4)
    /CONTRAST (conditions)=special(1 1 1 1)

    Bruce Weaver

    Spaces after the keyword CONTRAST have nothing to do with it--see below.  Looking at Martina's post again, I expect she wanted (1 1 -1 -1) where she has (1 1 1 1).  But again, if she says what contrast(s) she wishes to make, it will be easier to advise.


    * Example from:
    * http://www.ats.ucla.edu/stat/spss/faq/contrast.htm.

    * If your SPSS version does not support the Python-based
    * GETURI extension bundle, you'll have to download the data
    * file from www.ats.ucla.edu/stat/spss/faq/crf24.sav, save it
    * to your hard disk, and open it via GET FILE.


    * Carry out the three contrasts shown on the website, but
    * with a single GLM command rather than 3 separate commands.
    GLM y by b
      /CONTRAST(b)=special (0 0 1 -1)
      /CONTRAST(b)=special (1 1 -1 -1)
      /CONTRAST(b)=special (1 1 1 -3).

    * Now show that having blank spaces after the keyword
    * CONTRAST does not matter at all.

    GLM y by b
      /CONTRAST (b) = special (0 0 1 -1)
      /CONTRAST (b) = special (1 1 -1 -1)
      /CONTRAST (b) = special (1 1 1 -3).

  • Michael Päch added an answer in Polymer Synthesis:
    I am synthesizing phenol formaldehyde resins that are slightly yellow and transparent. How do I get them colourless?

    I have been using formulations from the 1920's and 30's from the patent literature to create the resole prepolymer.  There were a couple of cases that addressed this colour issue.  One that I found on my own was the use of a nitrogen purge throughout the prepolymer synthesis, which helped a lot.  It still gets slightly yellow and darkens upon curing.  Other methods have involved the use of neutralizing acid for the sodium hydroxide catalyst; lactic acid was used but this did not give clear resins.  Other concoctions have been suggested to bleach the resin with no help.

    Michael Päch

    So, was it colourless in the 30's?! I don't think so. Back then, phenolics were sold filled with some stuff disguising the natural tint.

  • Metwally Ezzat added an answer in Centrifuges:
    How can I remove any undissolved particles from the 2% chitosan (w/v acetic acid 1%) film forming solution?


    I have prepared chitosan film forming solution by dissolving 2g chitosan at 100ml acetic acid 1% and after stirring and good dissoving I want to remove any undissolved particles by whatman  paper no. 3 that is used in an article (Development and evaluation of a novel biodegradable film made from chitosan and cinnamon essential oil with low affinity toward water) but for its high viscosity it didn't pass from paper. I used the papers no. 2 and 1 but the result was same. I used centrifuge by 15000 g and there was no sedimentation. Can you help me how can I remove the undissolved particles?


    Metwally Ezzat

    Dear Mr. Masoud

    you can use vacuum pump to filter your solution.

    It can be appropriate way to filter your solution out .

  • Susan Kohut added an answer in Acupuncture:
    Does anyone have scientific research in the treatment of back pain with acupuncture?

    I´m looking for any research in backpain and acupuncture.

    Susan Kohut

    Acupuncture does have some problems in terms of scientific method, but there has been concerted effort over past years to mitigate against poor quality methodological approaches.

    However acupuncture (like other physical therapy-based interventions) continues to have the problem of sham acupuncture controls not being physiologically inert - i.e. most sham acupuncture controls can be rationalised using neuroscience, rather than traditional acupuncture theories, as being physiologically active.

    This is explained by the Society of Acupuncture Research article by Langevin et al (2011). http://www.hindawi.com/journals/ecam/2011/180805/

  • Ryan L Sontag added an answer in Cancer Metastasis:
    Does anyone have a protocol for isolating human cancer cells (breast) metastasized to mouse lung?

    I am using patients derived xenograft to study genes regulating breast cancer metastasis to the lung. So I will need to collect human breast cancer cells from the mouse lung.

    Thus I will need a protocol for lung dissociation and selection for only human cancer cells.

    Ryan L Sontag

    There are several ways, touched on above, but would require different markers for your cells. MHC, mitochondria, or a cancer marker (if known) antibodies can all be used with FACS, magnetic beads, or agarose beads. I suppose it really depends on what you want to do with the separated cells. Please contact me if you require any other information. Good luck!

  • Azad Adeeb asked a question in Project Design:
    What are the required data needed to run the STIMPRO simulation software for designing the Matrix Acidizing process?

    I am working on a project for designing matrix acidizing process for an oil well, and I am willing to use STIMPRO for designing that process. However I didn't have the chance to work on such a software before, that's why I would like to know, what exact data or parameters are needed to be inserted into the software to design the process?
    Any help would be appreciated.

  • Ali Alhayany added an answer 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

    Ali Alhayany

    Kiwi  is not a cultivated plant in our  country , we grow plants from seeds extracted from it,s fruit,so that i need help from that who have knowledge in this line

  • Igor Bayak asked a question in Minkowski Space:
    They can make friends theory of general relativity and the ether?

    Attempts to describe general relativity by a continuum in Minkowski space were made but were unsuccessful. Please see how it turned out in my article "Applications of the Local Algebras of Vector Fields to the Modelling of Physical Phenomena"

  • Wilfried Musterle added an answer in Consciousness:
    Is consciousness giving human beings an evolutionary advantage?
    While having the concept of Self as opposed to others or to the environment seems good for focusing the organism functions on survivability and on DNA spreading, is there any evidence that consciousness has an evolutionary advantage?

    To elaborate further, here I'm talking about consciousness as the first person experience. And for "first person experience" I'm not talking about "experience OF first person": conversly, I'm specifically addressing the "experience IN first person MODALITY" (as a corollary to this question, I'm proposing that the word "consciousness" refers to too many concepts). In this view, I consider self-consciousness "experience of first person in first person modality".
    If we embrace the assumption that consciousness is always consciousness of something, we still lack an explanation for the nature and the purpose ("what is/what's for" rather than "how is it") of the first person experience, and as such why evolution favored it.

    In a lot of other Q/A about self and consciousness people are talking about consctructs that may function even without consciousness. Two examples:
    -self: a neural network comprising semantic concepts about the world could very well include the concept of self as a non-other or non-environment, or even a concept of self as an independent organism with such and such features; why do we need consciousness to conceptualize it? Would a machine decoding all the concepts coming across the node of (or the distributed knowledge about) self be considered conscious? We do not have to attribute consciousness to the machine to explain the machine processing its concept of self.
    -thinking: processing is certainly different from consciously elaborate something, as all the studies on automatic and subconscious processing show. On the other hand, this point address the free will problem: when we consciously elaborate something, does it mean we are voluntarly doing so? Or are we just experiencing a first person "show" of something already happened subconsciously (as Libet's studies suggest)? Without touching upon the ad infinitum regression problems, this poses the question if consciousness is useful without free will: if the conscious experience is just a screen on which things are projected, no free will is needed and thus what's the whole point of consciousness? As such, do we also need free will for accepting consciousness? If we are working with the least number of assumptions, it seems unlikely the we can accept consciousness.

    It seems to me that the general attitude of cognitive theories in a biological information processing/computational theory of mind framework is to try to explain everything without putting consciousness in the equation. And indeed it seems to me that no one is actually putting consciousness in the equation, when explaining cognition or behaviour (at least in modern times).

    All in all, it seems to me that all the above reasonings bring the suggestion that consciousness is not needed and has no evolutionary advantage over automatic non-conscious entities. Or that we should make more and more assumptions (such as accepting free will) to make sense of consciousness.
    I think that asking why we have consciousness could lead us to understand it better.
    Wilfried Musterle


    I agree.

    may I add the idea, that the canvas and the painter are identical. This needs a strong feedback (resonance), but it is not recursive. I know that I know myself and other things in my conscious mind.

  • Pietro Pilo Boyl added an answer in Immunohistochemistry:
    Flouromount G lets in air as it dries, any solutions?

    For preparing IHC slides of rat brain sections, we mount with Fluoromount G, but it is common knowledge in the lab that over time it lets in air bubbles. Does anyone have any tricks to prevent or stop this? 

    Pietro Pilo Boyl

    Any mounting medium for fluorescence is water based and will dry out in time, shrinking its volume and producing bubbles. Therefore for long-term storage the slides must be sealed, typically with nail polish, better if transparent to avoid the pigments to diffuse in your mounting medium and raise the background.

    If you are doing classical IHC with dyes or coloured precipitates for bright-field imaging, then use a non-water based mounting medium such as Entellan or similar, which will dry without producing any bubbles. You can let the slices dry in the air for half an hour and then directly apply the Entellan, cover, and let it dry in a fume hood O/N.

  • Rahul Tikaram added an answer in Fisheries Biology:
    Should I use geometric mean values for 'a & 'b' from fishbase when calculating the weight of a particular genus of fish using the formula W = a × Lb?

    here is an example for the genus Diodon, is it ok if i use the geometric mean values as circled below?

    Rahul Tikaram

    Thank you Ken and Trevor, your comments are very valuable and informative. I have  basic knowledge on this and your ideas were very helpful indeed. 

    Just to give you an idea of what I am doing, I have catch records of reef fish from Fiji which are mostly subsistence in nature. This is basically what people from different parts of Fiji have been catching (i also have time spent fishing and the number of  fishers i.e effort). I would like to calculate the CPUE of each record and than show average CPUE by fish families, this means I have to calculate the individual CPUE for each genera caught (as species may not be 100% correct compared to genus, a reality of my data unfortunately). I have the lengths of the fish and want to use the formula W=a(L)^b to calculate weight, but i need a and b values, so i went to fishbase, and i was after the best values for individual genera. I still would like to know which values should I use for individual genera. Should I average all the a values for all the species given for a specific genera on Fishbase? 

    Ken and Ted your further insight to this will of great help, look forward to your advise. 

  • Sathish kumar Natarajan added an answer in Cell Culture Techniques:
    When a large number of estimations have to be done in a limited volume of sample, is it ok to pool samples from similarly treated cells/animals?

    Sample volumes are often small and a large number of different assays have to be carried out in a given sample. Under such circumstances, would it be ok to pool samples from 2 or 3 similar treated cells (for cell culture) or animals which have been treated the same way? What will the n number in such instances?

    Sathish kumar Natarajan

    Hi Joe,

    Pooling individual samples is not the best way to do. I would get help form your colleagues. Some researchers pool samples for big experiments like RNAseq to minimize the cost. I hope this helps.Sathish

  • Napoleon Ono Imaah added an answer in Urban Planning:
    How do I divide traffic zones in a city which has a circular radial network?

    How to divide traffic zones in a city which has a circular radial network

    Napoleon Ono Imaah

    Traffic zones in a city which has a circular radial network could be harmoniously  organized, not divided, and distributed as a taxonomy in accordance with their traffic discharge capacities:

    The traffic could be organized according to: Destinations - as internal circular routes and external radial routes ; Class of vehicles - as light and heavy duties vehicles; Links - as relationship of similar urban units - services centres, zones - industrial areas -  administrative headquarters -  transport hubs or nexus, etcetera.

  • Goffredo Angioni asked a question in Visceral Leishmaniasis:
    Have you experience with acute renal failure in Visceral Leishmaniasis treated with liposomal amphotericine?

    Do you know if is enough a single dose of Ambisome (250 mg, 2 hrs of infusion) to double creatinine level (1,3 to 2,8)?  or is more probable that there's another cause behind it?

  • Bahaa Badry Mosa Salim added an answer in Gene Ontology:
    GeneOntology: How might I find which molecular functions constitute a biological process?

    I am trying to use Gene Ontology and downloaded their database. Among many tables only very few contain relevant data. 

    The term table for instance contains the GO identifiers for all three parts: molecular function (MF), biological process (BC) and cellular component. GOC defines that a BC is something that has more than one MF.

    Where do I find the mapping of MF to BP i.e.: which MF come together to form a BP?

    The following SQL query which I tried returned nothing, indicating that this mapping is not available in the database.

    SELECT *
    FROM term t INNER JOIN term2term t2t ON t.ID = t2t.term2_id
    INNER JOIN term t2 ON t2.ID = t2t.term1_id
    WHERE t.term_type = 'molecular_function' AND t2.term_type = 'biological_process'


    Bahaa Badry Mosa Salim

    Dear Elena Eyr Sanchez

  • prof V.S Muralidharan added an answer in Potentiostat:
    Why is the voltammogram jumped up at low scan rates?

    It never happened to me before. The whole Pt voltammogram shifted up on the current scale at 20mVsec-1 and lower scan rates. Im using bio-logic potentiostat and microcell with 0.5MH2SO4 electrolyte.

    prof V.S Muralidharan

    the first step in voltammetry is keep the current scale (say) in one amp range

    Then you can improve sensitivity

    current is not  inversely proportional to sweep  rate

  • Hanie Kavand added an answer in Collagen:
    What is the Young's modulus of type I collagen fibrils?

    Weird or not, I've come across a range starting from 30 Pa to 5 GPa! Can someone please explain this range?

    Hanie Kavand

    Thank you.

    It states that:

    "The large variation of Er was mainly caused by three factors:

    1. Different individual fibrils.
    2. Different dehydration state of the fibrils.
    3. Uncertainties of the indentation process, mainly the contact area determination. "

    However, the Young's modulus report in the article and in the table presenting the previous measurements) are in GPa range!

  • Pietro Pilo Boyl added an answer in Horse Serum:
    Is there a difference between normal horse serum (NHS)/1% and sheep serum?

    Is there a difference between normal horse serum (NHS)/1% and sheep serum?
    I want to use it as a blocking medium for a staining of cryosections of mouse brains. Are there advantages for one?

    Pietro Pilo Boyl

    True what Sun Yung says, the theory goes that you should use for blocking the serum in which your secondary Abs are raised, in order to minimize at least that source unspecific background. In practice we don't notice much of a difference when the serum is not of the same species as the secondary Abs. It can often happen to use secondary Abs from different species (we typically have the older ones in goat, but the new ones are made in sheep or donkey) and in the end using NGS is fine anyway, and cheaper! If your primary Ab is crappy, there is little that the type of blocking can do to ameliorate your signal. But the serum concentration is important, and some primary Abs will need 10%, others max 5%, others max 2% of whatever serum, and finally others even will only work in just 2% BSA.

  • Jaykov Foukzon added an answer in Quantum Field Theory:
    Are there Lorentz invariant quantum field theories?

    The provocative question is motivated by the lack of non-perturbative regulators in quantum field theory which preserve the Lorentz symmetry. Higher order derivatives regulate the time reversal invariant sector only. Do we have to return to the idea of H. B. Nielsen about the recovery of Lorentz invariance in low energy effective theories?

    Jaykov Foukzon

    >Do we have to return to the idea of H. B. Nielsen about the recovery of Lorentz invariance in low energy effective theories?

    As we know main idea in this area based on Loop Quantum Gravity....

  • Lakshminarayana Bhatta K G added an answer in N2 Adsorption:
    How to interpret the following N2 adsorption/desorption isotherms?

    Sample 1: Carbon material (Lignocellulose was subjected to hydrothermal carbonization followed by calcination at 650 oC), Sample 2: Carbon material (sample 1 after KOH activation). I have referred a similar thread on N2 adsorption/desorption isotherms that was still open to discussion (https://www.researchgate.net/post/What_is_the_reason_for_the_open_loop_in_N2_adsorption-desorption_isotherm). Thank you in advance.

    + 1 more attachment

    Lakshminarayana Bhatta K G

    Thnk you Martin A Thomas for nice comments. I should discuss some of these points with operator.

    By the way, any idea on availabilty of facility for analysis using CO2 in Bangalore or India? I did try at few Indian Institutes of Technology (IITs) here in vain.  

  • Marc Tessera added an answer in Cognitive Systems:
    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.

    Marc Tessera


    " ''experiencing consciousness'' experiencing and consciousness are the same thing so one term is OK but the two !!!".

    Do you agree that there are different kinds of conscious experiences: 

    1. Feelings (which include the activity of the mood modules, as engaged by either emotions, sensations or cognition—i.e., all forms of affect);
    2. Sensing (input from sensory organs that may or may not activate mood modules);
    3. Cognition (thinking and related mental activity that may or may not activate mood modules.

    All these experiences are conscious but is it not possible to speak of unconscious experiences?

    According to you, does the sentence "the consciousness experienced by a dog is most likely different from that experienced by a human" is meaningless?