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  • Anne Staubitz asked a question in Synthetic Organic Chemistry:
    Who has experience using fast GC-MS as an analytical technique in organic synthesis?

    I'm in the process of setting up a lab in synthetic organic chemistry. We need a GC-MS and one option that was proposed was using fast GC-MS (by Shimadzu). Who uses this technique? How long are the measurements compared to standard GC-MS? We also need to quantify reaction products and side products. How good is the long term stability in terms of reproducability of the results?

  • Sunil Kumar Sahu added an answer in DNA Concentration:
    Does anyone know why the same sample amplifies with microsats but not with AFLPs?

    I'm using 8 microsatellite loci and AFLPs markers to evaluate genetic diversity of 9 populations (20 individuals each) of a walnut species using leave tissue as source of DNA. 12 out of 20 samples from the same population won't amplify with AFLPs but they have shown excellent results with microsats. This samples have excellent DNA concentrations and almost no inhibitors (according to NanoDrop 2000).

    Does anyone know why is this happening? if yes, What can I do to make my samples work?

    Sunil Kumar Sahu · Annamalai University

    Dear Daniela
    I do agree with the explanation given by Dr. Ajay Saini. However, I would like to know at which stage of AFLP anlaysis you are actually facing the problem, pre-amplification step or selective amplification?

  • Muhammad Salili added an answer in Ball Milling:
    Will toluene react with TiO2 in ball milling?

    I want to do ball milling of TiO2 using toluene so that powder will not stick with the balls. Now I want to know that will toluene react with TiO2 or not? 

    Muhammad Salili · Kent State University

    Take a look at this paper, it talks about different types of fluid that can be used as surfactants in ball milling including toluene.It talks about the effect of them on the formed particles.

  • Mariano Bizzarri added an answer in SH-SY5Y:
    Is it ok to prepare melatonin solution or H2O2 solution a day before treating to cells?

    Dear All,

    I am planning to study the effect of melatonin or H2O2 on different treating time periods to the cells, for example, treating at t0 (starting time) and t12 (after 12hr), then collect all samples at t24 (after 24hr).

    There two treating solutions: (1) melatonin solution (soluble in ethanol then diluted with complete growth media) and (2) H2O2 solution (diluted with complete growth media), and then store them one or two days at 4 degree C. before treating to adherent cells such as SH-SY5Y. To prepare melatonin and H2O2, a day or two before instead of prepare fresh, could help me reduce workload on the treating day.

    My questions are:

    (1) Is it ok to prepare melatonin or H2O2 a day or few day, instead of fresh to treat to cells?

    (2) If I prepare melatonin or H2O2 stock solution fresh and treat to cells at t0, Can I keep this stock solution at 4degreeC and use it again to treat to cells at t12? Or I should prepare another fresh solution with the same concentration at t12?

    Thank you so much

    Best regards,

    Mariano Bizzarri · Sapienza University of Rome

    No. It is better to prepare both H2O2  and melatonin solutions fresh every time you need



  • James Leigh added an answer in Tuberculosis:
    Is there a relationship between pulmonary cancer and tuberculosis?

    Is there any evidence of relationship, association or risk factor of having pulmonary tuberculosis for any form of pulmonary cancer?

    James Leigh · University of Sydney

    Some refs:

    Hinds et al Am Rev Resp Dis 1982;125:776-778

    Zheng et al Br J Cancer 1987;56:501-504

    Ko et al Int J Epid 1997;26:24-31

    Howe et al Int J Epi 1979;8:305-312

    Campbell Br J Dis Chest 1970;64:141-149

    Brenner et al Int J Epi 2001;30:118-124

  • Vadym Dolia added an answer in Oceanography:
    He studies the physical manifestations of spherical harmonics in geophysics?

    Hello Everyone!
    Tell me please, who is studying (studied) physical manifestations in geophysics, meteorology, climatology, oceanography spherical harmonics. For example 6-0, 6-4, 6-6? Articles, websites, software, database?
    Figures examples attached.
    Sincerely Dolia Vadym.

    Vadym Dolia · Ukrainian Hydrometeorological Institute

    Sincerely Vadym.

  • Sangeeta Bhattacharjee added an answer in Omnet++:
    Which network simulator is better among ns2 ns3 and omnet++ for implementing wireless networking algorithms?

    I want to address Physical/MAC/Network Layer and cross layer approaches for implementing wireless network algorithms. Which network simulator is advisable to use, provided i have no knowledge about any network simulator? My resources are limited to open source simulators- NS2, NS3 and OMNET++. 

    Sangeeta Bhattacharjee · Indian Institute of Engineering Science and Technology, Shibpur

    Thank you.

  • Hussien Elsiesy added an answer in Etiology:
    Do you check MDR mutation in cholestasis of unknown etiology in adult?

    I had an adult patient who presented with severe cholestasis, all the work up including liver biopsy was non conclusive, MDR stain in Liver biopsy suggested PFIC 3, genetic testing confirmed PFIC-3, PFIC-3 is not reported to cause severe cholestasis in the 5th decade of live.

    Hussien Elsiesy · King Faisal Specialist Hospital and Research Centre

    True, this is what we believe.  This probably explain the unusually late presntation

  • Andreas Bernreiter asked a question in Fungal Taxonomy:
    Are Mycosphaerella molleriana and Teratosphaeria molleriana synonyms and does Mycosphaerella leaf disease also include species from other genus ?

    I am not a specialist in fungal taxonomy ,,,,

    I am reading literature about eucalyptus leaf spot diseases. Literature tells me that there are many diverse fungi, which can infect eucalyptus trees. Furthermore Mycosphaerella leaf diseases (MLD) seems to be the major concern. Does MLD also include species from other genus such as Teratosphaeria. Teratosphaeria molleriana is often mentioned in connection with MLD.

  • Rongkang Deng added an answer in Microtome:
    How to slice, handle and stain embryonic brain tissue?


    Does anyone has experience with handling embryonic brain tissues? I tried to process some mouse embryonic day 14.5 brains. I managed dissecting the brains out, drop fixed them in 4%paraformaldehyde for a week (I guess this might be too long). I tried to section the brain on the freezing microtome, but the brain was so small and it was so easy to damage the tissue. I ended up getting very few intact brain sections. I used a small paint brush to transfer the tissue. That usually works fine for handling post natal mouse brain sections.

    I would greatly appreciate it if anyone can give me some suggestions.

    Best Regards

    Rongkang Deng · University of Maryland, College Park


    Thanks a lot! I'll try that.

  • Ankush Sachdeva added an answer in Cardiac MRI:
    Any ideas about surgery?

    A 12 years old boy with cardiac mri suggest fibroma tumor in rv, echodense, echolucent area in center,size=7 cm2 ,no symptom, arrythmia, hemodynamic effect.

    Ankush Sachdeva · Fortis Escorts Heart Institute

    The size of  the  tumor, if  suspected  fibroma can be chased on serial scans.A PET scan  can be done  for whole  body  to be sure  about  the  tumors nature  and any other  involvement. Biopsy  is always invasive and has its pros n cons. .so if really  warranted...

  • James R Knaub added an answer in Business Research:
    What indicates that your regression might suffer from an omitted variable bias?

    I am running a OLS regression model based on capital market and other disclosure data. My dependent variable is continuous (quality of investor relations) and my explanatory variable is binomial. I also have five other control variables which are continuous and/or binomial (from the literature and prior studies).

    My collinearity diagnostics indicate no problem and the Durban-Watson statistic is close to 2. The model is significant (p<0.001) and Adjusted R2 is .487. The standardized coefficient of my explanatory variable is .204 and significant (p<0.005).

    How would I know if there is any omitted variable bias? is there a test I can run, or to what should I look?

    I found the article of Peel in Accounting and Business Research (2014, 44(5)) and now I'm worried that I am missing something.

    James R Knaub · N/A


    Let me just add that R-square is a volatile measure, and p-values, being functions of sample size, may be nearly useless here. 

    One measure to consider may be the estimated variance of the prediction error.  Also, I think it important to consider heteroscedasticity. 

    If you are worried about bias, as well as variance, you could compare models using known test data, and see how well you predict in each case.  (Measurement error could complicate this.)  Just omit one known y-value at a time, and for each model, see how well you would have predicted for it in each case.  You actually might want to do such tests routinely.

    This is not only to compare models, but for a single model to compare the observed y-values to what would have been predicted had you not had them. This seems appropriate in your case, don't you think?  Perhaps you are already doing this. I am not familiar with your application or specifics.

    Graphical comparisons may be helpful too.

    With regard to the basic question, "What indicates that your regression might suffer from an omitted variable bias?" I wonder if that might put inflated emphasis on other terms, such as the intercept?  Could you perhaps find an unreasonable intercept term in your field of study with a type of model appropriate to your problem, if you had an "omitted variable bias?" 

    Cheers - Jim 

  • Omkar Pokharkar asked a question in Journalism:
    How to generate a DOI number for the articles?

    what is the importance of a DOI number and how can i get it for my articles if the journal does not provide it?

  • Shen-Ming Chen added an answer in Polyaniline:
    How can I functionalize polyaniline by specific material after polymerization?

    knowing that the material I want functionalize is liquid and polyaniline is powder in its salt form.

    Shen-Ming Chen · National Taipei University of Technology

    Conducting Polyaniline Nanowire and Its Applications in Chemiresistive Sensing

    Nanomaterials 2013, 3, 498-523; doi:10.3390/nano3030498

  • Manuel Morales added an answer in Black Body Radiation:
    Why is the energy of the CMB missing?

    The energy of a CMB photon when released is given by Planck constant times frequency; and also at arrival. Therefore, as frequency decreases with expansion, the energy at reception is S times lower, being S the space expansion since then. As S is around 1000, the CMB photons arrive with an energy that is only 1/1000 of their original energy; where is this huge missing energy?

    Reasoning in a different way, the energy density of a black body radiation is proportional to the 4th power of temperature, which shifts inversely to space expansion; so the energy density decreases with the 4th power but space expansion only accounts for the 3rd power decrease.

    What happens here? Is this a problem of missing energy? Or is this evidence that there is no conservation of energy over time?

    Energy conservation is a property of mechanical interactions that was assumed as a fundamental law; truly, we only have evidences of this law in interactions, but not through time with the accuracy required for applying it at cosmic scale.

    Conservation laws presume and imply an invariant, static, universe; but the universe is not static.

    What do you think? Is energy missing in cosmic radiation or the validity of conservation laws over time needs to be analyzed?

    Manuel Morales · TemptDestiny.com - Prephysics Research

    Yurji, in your book you stated, "Cosmology is based on theory (cosmological principles and theories of physical interactions) and observations (detection of photons and other cosmic particle). Thus its advancement is linked to the development of fundamental physical theories and the growth of observation data."

    Did you address how the two origin variables of selection caused the physical interactions in cosmology?

    CERN physicist, Adam Jacholkowski, earlier this year confirmed that particle collision experiments cannot take place without the selection event of two particle beams intersecting, no selection event - no interaction. And so by not accounting for which type of mutually exclusive selection event (direct or indirect) caused the particle collision effects, by scientific standards, a discovery cannot be made or founded on omitted-variable bias for it leads to false positive data. How can physical theories be fundamental if what causes our physical reality in not physical to begin with?

  • Shahabaldin Rezania asked a question in Cellulase Enzymes:
    How to prepare Cellulase enzyme (Aspergillus Niger) in saccharification stage for ethanol production?

    I need to know the details of method (Media, time and needed equipment)

    My biomass is Water Hyacinth (Lignocelulosic)

    Simultaneous saccharification and fermentation (SSF) 

  • Mattiullah Attari Butt added an answer in Likert Scale:
    How should one deal with extreme responses (All 5 or all 7 - Response Bias) in Likert Scales?

    How should one deal with extreme responses (All 5 or All 7 or All 1)? Can I give them the average score or must I exclude them? Any studies?

    Mattiullah Attari Butt · Huazhong University of Science and Technology

    Thank you professors,

    Prof David, The question is about rating different management practices in a Faith based Volunteer Organization. Some Volunteers have scored all the management practices as 5, which I think does not make sense. One item is reverse coded out of 14. I feel it to be religious influence scoring every management practice as maximum and it does not make sense to me. You may please guide about it too..... 

  • Md Rasheduzzaman Al-Amin asked a question in Mesh Processing:
    Solid requires higher meshing process In HFSS?

    In HFSS, when a metal is selected and validation is carried upon it says that is this is a solid which require higher meshing process. it ultimately shows completion of analysis with execution error. how to i define a meshing process for metal like aluminium,copper given the structure is corrugated

  • Misha A. Shevelin added an answer in Commutative Algebra:
    How can I prove the following statement?

    Let A be a commutative nil-algebra of nilindex n and dimension finite over an algebraically closed field of characteristic not 2, such that there exist a non zero ideal I such that I=AI. (but I \cdot I \neq I. because in this case, Dr Misha constructed a counterexample)

    Then Null(A) \cap A^2 = {0}.

    By A a commutative finite-dimensional algebra means a vector space of dimension finite over a field k with a generic simetric bilinear operator. In this particular case, additionally the product satisfy for every x \in A x^2 x^2= x^4. (Commutative power-associative algebras).

    By nil-algebra of nilindex n means that for every a \in A, and every arrange of n products of a, this product is zero.

    This particular kind of algebras are not associative, and  don' t have 1.

    By Null(A) means the set of elements a \in A such that the right multiplication map R_a (or equivalent, the left map L_a) is the zero map.

    Thanks everybody, and I'm sorry for all my mistakes.

    Misha A. Shevelin · Luxoft

    Something you should have: http://www.ams.org/journals/tran/1966-121-01/S0002-9947-1966-0202782-5/S0002-9947-1966-0202782-5.pdf

    Also I've found: Whether or not the new definition of simplicity is an actual restriction
    is not known. That is, whether or not commutative powerassociative
    nilalgebras without proper ideals exist (except of course
    for the zero algebra of dimension 1) is still an open problem.


    So it's a very serious problem (If it haven't  been solved yet.)

  • Shen-Ming Chen added an answer in Electrodes:
    Explanation about EIS data?

    In the attached picture .. is the figure i get from EIS analysis using verastat 3 potentiostat using 3 electrode system where (Platinum coil was counter electrode + Ag/Agcl (Nacl saturate) as reference electrode + MnO2/CNWs as working electrode in 0.5 M Na2So4..

    I noticed that most of samples make such shape which is not expected i expected low frequency arc followed by high frequency line .. 

    so, does any one experienced the same ? or any explanation for such behavior ?? 

    Thanks in Advance

    Shen-Ming Chen · National Taipei University of Technology

    Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitor

    Nanoscale Research Letters 2012, 7:33

  • Anilkumar Moola added an answer in Photosynthesis:
    In Photosynthesis, how does P700* is act as strong reducing agent?

    Generally In Photosynthesis Photosystem II oxidized by using electrons from water molecules directly and got exicited ( that is P680*) Where as  P700 will exicited with series of electrons. I am little but confused How P700 is act as good reducing agent in Phosynthesis? At the same time in cyclic process P700 is First electron donar and Last electron acceptor?  

    Anilkumar Moola · Bharathidasan University

    Respected Arjun Sir 

    Good Morning! I really excited with your answer (electrons) and i am excited with your answer sir.

    As per your suggestion i refer some more books. Thank you for your constant support.

    With Regards

    Anil Moola 

  • Vivek Chauhan added an answer in Critical Care:
    Are there any critical care documents EWS, Evaluation and Daily entry charts available in the public domain for use in Africa?

    Are there any Critical Care documents EWS, Evaluation and Daily entry charts available in the public domain for use in Africa

    Vivek Chauhan · Dr Rajendra Prasad Government Medical College

    You can try ICU-CAM, APACHE 2, and SEWS Scoring charts. All are available in public domain.

  • Rodrigo Saens added an answer in Wine:
    What are the determinants of collective (group) reputation in the wine market?

    I am analyzing whether or not the reputation of a region/country in the international wine market depends on a country’s efforts to specialize in a specific grape variety.

    Rodrigo Saens · Universidad de Talca

    The results of my study show that although variety specialization has successfully underpinned the reputation of some New World regions, such as the Napa Valley (with its Cabernet Sauvignon) or Oregon (with its Pinot Noir); in others, such as Australia (with its Shiraz), this has not been successful.

  • Wei Zhang asked a question in Citizen Participation:
    Is there any comprehensive category for political issue?

    Based on my observation, the category could be based on two measurement. a) the complexity and salientness of the issue by Gormley (1986) referring to citizen participation; b) the theme of the issue, i.e., domestic vs internaitonal affairs, education policy, enviornment policy. However, I am not sure about the categories. Sometimes, I find that a simply ecomonic issue could turn out to be a political issue as well. If it is the case, what is the difference of political issue and public issue? Can anyone recommend classic reference addressing this problem? 

  • Wan Mohamad Asyraf Wan Afthanorhan added an answer in Mediation Analysis:
    How do we perform mediation analysis in SPSS?

    I want someone out there to assist me with the software that permits mediation analysis in SPSS. 

    Wan Mohamad Asyraf Wan Afthanorhan · Universiti Sultan Zainal Abidin | UniSZA

    You can try PROCESS in SPSS. Please read the attached file:

  • Beverly Chittoo asked a question in Attachment:
    Can anyone explain how I can use a neural network performance plot to determine if my data has been over fitted?

    Can anyone explain how I can use a neural network performance plot to determine if my data has been over fitted? The attached document shows the performance plot obtained after retraining.

  • Wan Mohamad Asyraf Wan Afthanorhan added an answer in AMOS:
    What is the best way to conduct path analysis with an ordinal end variable?

    I would like to test a path model in AMOS. However, as the end variable is ordinal (four response categories) I am uncertain as to the best way to deal with this. I know that Likert-type measures are often entered into SEM despite technically being ordered data. However, in this case I do not think that the categories – while clearly ordered – could be reasonably regarded as quasi-continuous, as they represent “levels of investment” rather than numeric rating scales. There is also quite a lot of positive skew in the responses. I was wondering what people’s thoughts were on the best way to deal with this?

    Wan Mohamad Asyraf Wan Afthanorhan · Universiti Sultan Zainal Abidin | UniSZA

    If you interest to apply the categorical outcome in SEM, you have to use mean and variance adjusted weighted least square or diagonal weighted least square estimator (DWLS). But this estimator can be found in Lavaan or Mplus.

  • Philippa Ojimelukwe added an answer in Probiotics:
    What kind of probiotics have the two advantages of both easy colonization in human gut and suitable for secreted expression of protein of interest?

    What kind of probiotics own the two advantages that both easily colonizes in human gut and is suitable for secreted expression of protein of interest? Is there some systematic literature for reference? Thanks in advance.

    Philippa Ojimelukwe · Michael Okpara University of Agriculture, Umudike

    I have done some work with several strains of probiotic lactic acid bacteria. Lactobacillus plantarum shows good colonization potentials and also expresses some important proteins.  You can read the research publication by Herias et al., 1999 " Immunomodulatory effects of Lactobacillus plantarum colonizing the intestine of
    gnotobiotic rats" Clinical Experimental Immunology. , 116:283–290. All the best!

  • Wan Mohamad Asyraf Wan Afthanorhan added an answer in Structural Equation Modeling:
    How can i test the goodness of fit of a hypothesized model with the help of Structural Equation Model (SEM)?

    Actually Preliminary guidelines are required for me. Can any one Help me please in this regard?

    Wan Mohamad Asyraf Wan Afthanorhan · Universiti Sultan Zainal Abidin | UniSZA

    There are several fitness index should be meet such as:

    1. RMSEA<0.08

    2. GFI>0.90

    3. AGFI>0.90

    4. CFI>0.90

    5. TLI>0.90

    6. NFI>0.90

    7. Chisq/df<5.0

    You have to meet that requirement when do assessment for measurement model. If not achieved, you have to delete meaningless item by inspecting through the Modification Index table. This report will be help you to identify the multicollinearity problem.