Q&A

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  • Ahmed Nasr added an answer in Clomiphene:
    What is the expected time for disappearance of clomiphen citrate from blood after the last dose ?

    .

    Ahmed Nasr · Assiut University

    Long known as an ovulation initiator, clomiphene citrate is the best studied long-acting SERM with a relatively long half-life of 5-7 days. That, multiplied by 5 or 6, yields an approximate estimate of the time lapsing before it disappears from the body (25-45 days). Hope this helps !!!

  • Do I need precise collection data for a species description paper?

    Someone is sending me 15 Blattidae sp. "African Bullet" roaches so that I can formally ID them and publish the species description in a scientific paper. This species has been commonly misidentified as Bantua robusta.

    The roaches originate from a domestic colony. Apparently the founding individuals were collected from a log at the base of Mt. Kilimanjaro, but that was the only information he could provide me. There was no mention of when the wild roaches were collected, exactly where on the mountain, if any new individuals were added to the colony after the initial collection, etc.

    Would this limited information be acceptable for describing this species?

    Jordan Landerman · California Polytechnic State University, San Luis Obispo

    Thanks for the answers everyone. I am going to proceed with writing the paper anyways, since I haven't been able to find anyone reliable who'd be willing to go out and collect them for me from the wild. Let's hope that it works out!

  • Erik Rakovský added an answer in X-Ray:
    Which is the best (and user friendly) Single-crystal X-ray diffractometer on the market now?

    We are a research group in an academic institution and looking into buying a diffractometer for single-crystal X-ray studies of small molecules. We want an instrument combining excellent capabilities with a user-friendly interface and great customer support. Any suggestions on this? Thanks! 

    Erik Rakovský · Comenius University in Bratislava

    My direct experience with Rigaku software is only with CrystalClear (for CCD/HPAD), but it is not possible to use narrower scans with IP? With Stoe IPDS it is not any problem using the same frame widths (1° default) like with their CCDs/HPADs, I would be pretty disappointed if it is not an option with Rigaku.
    The software is a matter of practice - I do almost anything with both Apex2 Suite or CrysAlis, but with CrysAlis I am blazing fast because of using Kuma/OxDiff/Agilent for years.

  • Yasser M. Abd-elrhman added an answer in Wear:
    How is it possible that the wear rate of composites which have more hardness increased?

    How is it possible that the wear rate of composites which have more hardness increased?

    Yasser M. Abd-elrhman · Egypt-Japan University of Science and Technology

    I obtained similar results before for my boronized steel, and I extensively investigate the morphology of the boronized layer and we found that the hardened layer is peeled up and this is the reason for the high wear rate. so I advise you to check your worn areas maybe you will find peeled up laminates or heavy rupture for them.

  • Mila Pravda added an answer in ISO:
    Why are most of the many published point-of-care (POC) or lab-on-chip (LOC) testing devices not available on the market?

    Can it be that the most authors and researchers have neglected and still do not follow the demands of the following ISO norms (with year of coming into effect): 15193 (2002); 15194 (2002); 15195 (2003); 17511 (2003); 18153 (2003) and especially: ISO/PDTS 25680.8: Use of external quality assessment schemes in the assessment of the performance of in vitro diagnostic examination procedures? This European Standard was approved by CEN on 2 March 2004 as EN 14136. Why do most published papers in this area not perform the minimum performance test by taking part in an inter-laboratory trial with real samples and not with pure aqueous solutions without a possibly interfering matrix (e.g., in bio-sensing: enzyme-poisoning, denaturing reagents, proteases, drug-metabolites, etc.)?

    Mila Pravda · University College Cork

    Perhaps, one could ask the question why are such manuscripts still being accepted?

  • Radoslaw Chrapkiewicz added an answer in Holography:
    What are the most efficient ways to retrieve and unwrap the phase from a single interferogram?

    I am aware that single interferogram does not have all information you need and you have to utilize some extra assumptions.

    Nevertheless what methods and algorithms are used in such a case?

    Radoslaw Chrapkiewicz · University of Warsaw

    Thank you very much for the clue and the starting point, I'll read about this "flynn unwrap".

  • Piotr Bąska asked a question in Transfection:
    How can I identify gene promoter (Cis-regulatory element)?

    I want to check if promoters of a few genes (from cattle) are active in the cells. I want to clone GFP under the promoters and transfect the cells with the vector. The problem is I don`t know the promoters. How can I identify the promoters. Would it be OK if I clone 200 – 300 bp of 5` untranscribed region assuming the promoters are there?

  • Does anyone have a suggestion to remove LPS from recombinant proteins, If the recombinant proteins bind to LPS?

    All proteins are not in the inclusion bodies (all of them in the soluble fractions). Proteins were previously purified by His-tagged cobalt resins. We have used the Pierce High Capacity Endotoxin Removal Resin to remove LPS from three recombinant proteins, but the recovery of the proteins appear to be proportionally dependent to LPS concentration in the final sample (LPS measured by LAL Chromogenic Endotoxin Quantitation Kit) - much low recovery of recombinant protein (Quantification of protein by BCA protein assay). 

    Steingrimur Stefansson · HeMemics Biotechnologies Inc

    Hi Fernando, the Pierce High Capacity Endotoxin Removal Resin is immobilized poly-lysine. It essentially is an anion exchange column. LPS is negatively charged and binds to this resin.

    If your protein binds lipids, and if the only lipids in your prep is LPS, then you will lose a lot of your protein.

    Possible solutions: if your protein binds lipids, add octyl glucoside to it before putting it through the LPS removal column.

    If your protein is negatively charged and does not bind LPS,  you can try TX-114 phase separation.

  • Intan Dinny asked a question in Quinine:
    Can Cinchonidine synthesized by Quinine?

    What is the reagant and mechanical reaction?

  • Washington Aliaga added an answer in Clay:
    What is the best way for avoiding entertainment of fine particles (normally clays and finer than 10microns) in froth zone of flotation process?

    What is the best way for avoiding entertainment of fine particles (normally clays and finer than 10microns) in froth zone of flotation process. How about application of dispersing/depressing agents and also oil addition during conditioning? 

    Washington Aliaga · University of Santiago, Chile

    The other method is to regulate bias water to clean up bubles from fine particles for entrainment (Is this what you meant?)

  • Charles Fisher asked a question in Clathrin:
    What is the largest sized structure that can be internalized through clathrin mediated endocytosis?

    What is the size limit for a structure to be internalized into a cell through clathrin mediated endocytosis before another process, e.g. phagocytosis takes over for endocytosis? We have a large structure that can be internalized into cells around 5um in size and are trying to determine if it is a clathrin mediated process. 

  • Syed Wali Peeran added an answer in Bone Grafting:
    What is your protocol for when an indispensible instrument or 'bone graft' falls onto non sterile area?

    Patient may be unconscious, sedated or fully conscious.

    Syed Wali Peeran · Sebha University

    Always start with backup instruments and material. In dental operatory with autogenous bone graft we can be in real trouble especially if source was intra-oral and the patient is on the chair.   

  • Mila Pravda added an answer in Biosensors:
    Biosensors: cleaning the analite so the biosensor can be used again. If we are detecting a bacteria, is it absurd to use an antibiotic as a cleaner?

    It can't affect the immobilized antibodies.I thought of using Ag nanoparticles, but this may clutter the device by adsobing to the walls.Is there other bactericidal solutions, something I could use to rinse the bacteria, without affecting the immobilized molecules?

    Mila Pravda · University College Cork

    Yes, it is worth trying. The problem is that the act of killing or inhibiting the bacteria does not break the bond between the surface groups bound to the antibody and regenerating the immunosensor. I think this may be best using electric impulses like in this patent: 

  • Library and Information Studies history - do you have any bibliographic suggestions?

    I am interested in articles on the history of LIS studies - especially in Spain and Poland.
    But also in European countries. Do you have any brilliant suggestions?

    Vladan Celebonovic · University of Belgrade

    Perhaps yes. I know that some  time ago the man in charge of the archive at the Astronomical Observatory in Belgrade published a book on their archive. Their website is www.aob.rs, and his name is Mr. Radovanac.

  • Patrick Druggan added an answer in Fixed Cell:
    How can I remove bacterial contamination from fixed human cells?

    I have some precious samples I need to image but they are covered in bacteria. The main issue I have is I stained them with Hoescht and the bacteria have taken this up so that I can no longer "see" the cell nucleus. 

    So is there a way to decontaminate fixed cells?

    Patrick Druggan · Synergy Health, Chorley, United Kingdom

    I don't think you can with fixed cells

  • What is the best clinically approved MSC media to be used for clinical trials?

    Hello everyone,

    I need details about mesenchymal stem cell (bone marrow stem cell) media which can be used for clinical trial studies and which is clinically approved.

    Our application can also involve the injection of this media into patient. I need media which is safe for human applications and properly approved clinically.

    Please add your suggestions.

    Carolina Arruda de Faria · University of São Paulo

    At the moment I am in pre-clinical research, so I am not using any. But in the MSD the manufacturer informs if it is suitable for clinical research or not. I didn't find any in the Sigma catalog, but I  found several culture media classified as suitable for clinical research in the Gibco and Cutilab catalogs. You just need to find the most appropriate for your cells and classified as clinical compatible. Sorry, I wish I could be more helpful.

  • Vladan Celebonovic added an answer in Universe:
    Will we ever meet our interstellar neighbours?

    Somewhere 'out there' in interstellar space are people like us, wondering if they are alone in the universe.

    Will we ever meet them to do the laws of physics prevent that ever happening?

    Vladan Celebonovic · University of Belgrade

    Purely logically, I can not think of a single valid reason why we should not meet those people "out there". The basic assumption is that we look for them long enough and hard enough, where " long enough" may mean a billion years.. If your question means "will we meet them in our lifetime"...my answer is " I doubt.."

  • Sabino Maggi added an answer in Academia:
    Do you have experience with caste employment at Universities in spite of the law?
    There are many examples of illegal employment of children of professors. It is an ethical issue. It is about nepotism. Rectors of the University of Novi Pazar, in Serbia, hired several members of their closest family, although there were better candidates for the academic places. Do you have experience with such phenomena?
    Sabino Maggi · National Research Council

    @Sara,

    nepotism in universities and public research organizations is very common in Italy too. Scandals surface nearly daily but italian society is very lax about these ethical issues.

    A very good account can be found in this news article Nepotism alive and kicking in Italy (http://www.bbc.com/news/magazine-21507168) and in the referenced paper Academic Dynasties: Decentralization and Familism in the Italian Academia (https://ideas.repec.org/p/nbr/nberwo/17572.html).

    I agree with Abderrahmane Kadri and others, it is not a question of being a developed or an underdeveloped country, rather a question of the society which is behind the academic world. When the society is corrupt or does not sense corruption as an important ethical issue, also academia will mirror the behaviour of the society in which it is immersed.

  • Steingrimur Stefansson added an answer in Chitin:
    How do you elute Chitin-bind protein form chitin resin?

    Thanks.

    Steingrimur Stefansson · HeMemics Biotechnologies Inc

    Hi Tengfei, have you tried organic solvents, like 10-25% DMSO or isopropanol?

  • Chang-Er Chen added an answer in Metabolites:
    Which LC-MS/MS is better for metabolomics: LTQ Orbitrap Velos or LCMSMS-3200 Qtrap?

    Hi,

    I'd like to profile and compare a number of metabolities between cell types.

    As I am new to LC-MS/MS, please kindly advice which below instrument would be more useful:

    • LTQ Orbitrap Velos
    • LCMSMS-3200 Qtrap

    Is it that a LC-MS/MS firstly performs untargeted profiling of all metabolites, then a 2nd round of MRM for selected metabolites? Could this be performed in a single instrument (e.g. the ones above)?

    In that regard,

    • Would a lot of starting materials needed?
    • Why would a 2nd round of MRM needed, if the metabolities of interest could be profiled in the 1st untargeted run?

    Thank you very much

    Chang-Er Chen · Lancaster University

    targeted Quantification, then go to Qtrap.

    untargeted identification, then go to LTQ.

  • Louis Brassard added an answer in Computer Science:
    What happened with “The Fifth Generation Computer Systems project (FGCS)”?
    Back in 1982, Japan's Ministry of International Trade and Industry, begun the project “The Fifth Generation Computer Systems project”. The idea was to find the new architecture of computer, i.e. NON Von Neumann architecture, with Sequential Inference Machine Programming Operating System (SIMPOS) operating system is released. SIMPOS is programmed in Kernel Language 0 (KL0), a concurrent Prolog-variant with object oriented extensions. Similar project was in US, the results were various Lisp machine companies and of course, Thinking Machines.

    I’m interested what happened with Japanese “Prolog machine”? Does anyone know something about that?

    Ljubomir,

    As most people in that field I was just naively following the so called guru and like them thought that to succeed we just need a technical solution, a kind of arrogant hacking mentallity.  And as all naive arrogant people who do not know the human history of thought you are doomed to repeat the errors of the past.  Luckily I had some solid background in science, engineering, mathematic and history and when I hit the wall around 1993-1994,  I was not helpless as those that only knew what a computer is and knew a few computer languages. Those are two artefacts created in the spirit of the Hilbertian logico mathematical physical culture of the 19th century, itself a relic of the crumbling Laplacian universe.  A direct incarnation of the mind body separation built at the core of the cartesianism of modern science. The computer/software separation symbolized that body/thought separation of cartesianism and trigger a culture of representation within the machine of the external reality and the machine is mostly symbolizing a desimbodied brain!!!  The connection to the world that a body is , is absent as it is absent in mathematic based on axioms.   If this is your only default culture , we wont be able to get out.  I had a tiny bit of culture which allowed me to began to search (not to hack) my way out of this mess.

  • Ravi Thakur added an answer in MCF-7 Cells:
    Has anybody worked with xenograft model of rabbit for tumor using cell line?

    I am working on xenograft model of rabbit for tumor induction and I have certain issues in setting my protocol. Can anyone plz help me in this regard. I am working with MCF-7 cell line..

    Ravi Thakur · Central Drug Research Institute

    Hi,

    Xenograft means that you must be injecting the MCF7 cells (as you mentioned) in Rabbit. Well for that you may require immuno-compromised rabbits. To my knowledge immuno-compromised rabbits are not easy to make and easy to rare. 

    Alternatively a syngenic model is possible. Where  a rabbit cancer cells are injected into a rabbit. As cells belongs to same species there are lesser chances of immune clearance. I searched online and came across no rabbit breast cancer cells, you can try searching if one is available. 

    In this case you can think of a third option, inducing a tumor using carcinogens. MNU, DMBA, B[a]P are some carcinogens used to induce tumors in rodents like mice or rats. You can try one in rabbit. 

    I don't know what kind of experiments you are planing. But in general. it is always better to use a mice or a rat model for cancer studies. Immunocompromised mice are available commercially, you can inject MCF7 to get tumors.

    Alternatively 4T1 mouse mammary epithelial cells are also available with ATCC. They form tumors even in normal Balb/c mice. This model works well if one does't have access to immuno-compromised mice.

    Though, there are limitations with both xenograft and syngenic models. Xenograft works well to study in-vivo effects on human cancer cells and syngenic works well if one want to study  tumor (mouse) biology in physiological conditions. You can chose one according to your problem.

    All the best.

  • Paweł Linek added an answer in Ultrasound:
    Is ultrasound a validated imaging technique to measure muscle mass, muscle fat composition and thickness in human skeletal muscle?

    I am looking at using ultrasound to measure human skeletal mass especially TA and gastroc muscle. I want see if ultrasound is as validated as MRI in defining above parameters. Any advise or suggestions welcome. Thanks

    Paweł Linek · The Jerzy Kukuczka Academy of Physical Education

    In general I agreed with above opinion. If you look at other muscles, you can see that such simple parameters like thickness or CSA are depends on operator's skills, experiences and the like.

    But In Recently published paper, the authors claim that ultrasound is appropriate and useful for evaluating skeletal muscle mass.

    Look at:

    http://www.ncbi.nlm.nih.gov/pubmed/25444689

    It may be helpful.

    Regards,

    Linek

  • Hana Bensalem added an answer in Video Analysis:
    Is there any behavioural coding scheme I can use to measure Sense of Presence?

    I will run an experiment with a driving simulator and oculus rift. I would like to analyse the behavioural responses through video analysis. Does anyone know a scheme of behaviours that is correlated with Sense of Presence? 

    the question is:

    what is presence and wich part  could your envirment detect?

    so,in your answer  you found the  scheme.

  • Patrick Druggan added an answer in Agar:
    How can I inhibit fungal growth in nutrient agar without affecting the pH of the agar?
    Specific antifungal to use and measurements.
    Patrick Druggan · Synergy Health, Chorley, United Kingdom

    cycloheximide or amphotericin B. 

  • Raid Amin added an answer in E-Learning:
    What are the top effective roles of instructors should be focused for fully e-learning course operation?

    I am trying to get the answers to the question "What are the top effective roles of instructors should be focused for fully e-learning course operation?"

    Raid Amin · University of West Florida

    Our entire graduate profram is taught simultaneously online and face to face. I have some students in the class rom, while other students are distance students. All lectures are taught synchronously live to all students. All lectures are recorded,  and all lectures are posted online. Students work in groups, with extensive student mentoring and discussions.

  • Does “spin” imply physical rotation?

    The “spin” of an electron or other fundamental particle is often described as “intrinsic angular momentum”. This terminology is required because a point particle or Planck length vibrating string cannot possess ½ ħ of angular momentum. Larger objects such as molecules or electrons in atomic orbitals possess quantized angular momentum which can be demonstrated to involve physical rotation. For example, a carbon monoxide molecule in a vacuum can only rotate at integer multiples of 115 GHz which is integer multiples of ½ ħ. Therefore, do you believe that fundamental particles have a physical angular momentum that is currently not understood? Alternatively, is "intrinsic angular momentum" an accurate description of spin because it is a quantum mechanical property that does not involve physical rotation?

    Charles Francis · Jesus College, Cambridge

    Sanjay, essentially, yes, but a Dirac spinor is a four spinor. It has four degrees of freedom, to describe antiparticles and particles as well as the two spin states.

  • Raid Amin added an answer in MANOVA:
    Is it ever correct to use ANOVA for multiple dependent variables?

    As far as I understand, if one wishes to analyse multiple DVs, MANOVA should be used. Risk of Type I errors will be increased by performing multiple ANOVAs or multiple t-tests without corrections. However, I have seen several publications where a single ANOVA is used and multiple DVs are entered as a factor. Is this ever advisable, and if so what is the rationale?

    Thank you

    Raid Amin · University of West Florida

    It is difficult to give a correct answer to an open question. If I knewabout so e experiment, I could maybe discuss the models that could be used for reasonably good results. The researcher decises which caraibkes are respobse varaibkes and which variables are classification factors. Each approach addresses different hypotheses.

    Typically, the variables of interest are the response variables that we want to study.