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  • Any suggestion about rural livelihood and entrepreneurship?

    Hello dear mates

    I´m using the capital (assets) of livelihoods (social, financial, human, etc) to understand how rural people start business and manage them. So i would like to see if any author had something with that


  • What are the reasons a PCR that once functioned, is not working anymore?

    Last week two Test-PCRs for a new set of primers worked quite well and i got one defined product band.

    One week later i am not able to get any product again. I exchanged all materials, also the template (cDNA) i also tried reamplification from pcr product of the test PCRs.

    Now i am wondering, why the pcr is not working anymore? Can Primers degrade within such a short time? Would it be senseful to run the primers on a gel electrophoresis?

    Thanks for your suggestions and your answers!

    Joydip Karmakar · Visva Bharati University

    Theresa, I also had the same problem like u.

    I think u can do the following things

    1) Check the water quality, used for primer dilution (I think u used Mili Q water)

    2) If u designs the primers and used it first time then u has to re-conform the primers bioinformatically, their binding site, product site etc (though you have a definite product previously, but it happened sometimes...)

    3) If u sure about primer design then the manufacturerization of the primer is not done well. Sometimes some salt can hamper the PCR reaction. In my case I ultimately found that the new set of primer (purchased again, HPLC grade) working well. If u using desalted primer u can use HPLC grade primer.

    So I think, brought one set of primer again and check it. I can say from my own experience, this can save lot of time as because I lost mine for the same reason.

  • Juehui Shi added an answer in Normal Distribution:
    What is the minimal number of observations needed for normal distribution?

    Why does a sample size greater than 30 approximate the normal distribution?

    Juehui Shi · University at Buffalo, The State University of New York

    For any type of normality test and other hypothesis tests, you want as many samples as possible for robustness (strong statistical power to get unbiased results).

  • Yu-Kun Wang added an answer in Polarity:
    Does anyone have experience using Comsol for polarizer?

    I don't know how to set up the frequency and transmission. I even don't know how to input formula and use it because the model library is using like coding formula.


    Yu-Kun Wang · National Yunlin University of Science and Technology

    I want to solve the question like this in Comsol. Thanks for answer me!Hope other can answer me. 

  • Why do we use schottky contact and not ohmic at the gate terminal?


    Md. Nur Kutubul Alam · Khulna University of Engineering and Technology

    Main objective is to change the potential at the channel by applying a voltage at the gate. It changes the gate capacitance and turns on/off the device. However, we don't want the current to flow through the gate terminal.

    Schottky contact produces an energy band discontinuity between channel and gate contact, known as "Schottky barrier". It blocks the electron to flow from the channel to the gate and vice-versa. (Of course this barrier is made by depleting the channel.) On the other hand, (ideally) there is no band discontinuity or barrier in the ohmic contact. Therefore if you apply a voltage in ohmic contact, current will flow through that. Source and drain are made of ohmic contact.

    Placing an oxide in between gate metal and semiconductor channel is relatively effective than Schottky contact. This architecture is the well known "MOSFET". 

  • Guillermo R. Labadie added an answer in 2D-NMR:
    How to confirm using 2D NMR whether the isolated Rosmarinic acid is R or S isomer?

    How to confirm the stereochemistry of RA

    Guillermo R. Labadie · National Scientific and Technical Research Council

    The problem is enantiomers have identical properties in an achiral environment.

    So, there is no difference in normal NMR experiment.  

    Because enantiomers have different properties in a chiral environment, they can be distinguished in a chiral environment such as a chiral solvent, or complexed with a chiral shift reagent. 

    To solve your problem, if you know the reported specific rotation of the natural Rosmarinic acid, that seems to be thr R, you can just confirm the configuration checking the specific rotation. 

  • Which methodology is the best for bacterial capsule staining?

    Fundemantal Microbiology Laboratory

    Shraddha A Sane · Gujarat State Fertilizers and Chemicals (GSFC)

    this may not b best but easy and we use regularly


    A. General materials
    • Staining tray
    • Staining rack
    • Slide holder
    • Disposable gloves

    B. Staining reagents

    • Crystal violet 1% solution (primary stain)
    • Copper sulfate 20% (decolorizer agent)

    C. Procedure

    1. Prepare a smear from a 12- to 18-hour culture grown in milk broth or litmus milk. (Serum protein may be used to prepare the smear if the organism was not grown in milk broth or litmus milk.) This is to provide a proteinaceous background for contrast.

    2. Allow the smear to air dry. DO NOT HEAT FIX (to avoid destroying or distorting the capsule or causing shrinkage).

    3. Cover the slide with 1% crystal violet for 2 minutes.

    4. Rinse gently with a 20% solution of copper sulfate.

    5. Air dry the slide. DO NOT BLOT. (Blotting will remove the un-heat-fixed bacteria from the slide and/or cause disruption of the capsule.)

    6. Examine the slide under an oil immersion lens. Bacterial cells and the proteinaceous background will appear purplish while the capsules will appear transparent.

  • Adam B Shapiro added an answer in DNA:
    Is DNA can be quantify accurately without using nanodrop?

    I am quantifying the DNA on nanodrop 1000. when i dilute the DNA and quantify, it gives more concentration than the diluted concentration. How can i overcome this problem?

    Adam B Shapiro · AstraZeneca

    I don't have experience with the Nanodrop. You probably can't change the pathlength. With a cuvette-based spectrophotometer, you can use cuvettes with various pathlengths, but the volume required is much more than with a Nanodrop.

    When you say the Nanodrop gives you a value of 13 to 22, what do the numbers refer to? Is it the absorbance? What is the dynamic range of the instrument?

  • László Kótai added an answer in Fermentation:
    Is there any specific enrichment process for bacterial conversion of acetate or butyrate or carbohydrates to particular type of solvents (alcohols)?

    Hi all, I am currently attempting to generate any one or two particular type of solvents such as ethanol, methanol, etc., for the generation process I wanna use enriched anaerobic fermentation bacteria (Mixed culture) with suggestible carbon source. From the literature I could find only studies operating with pure culture, so kindly suggest me some enrichment process for mixed cultures to convert  carbohydrates or VFA's to specific type of solvents.

    László Kótai · Hungarian Academy of Sciences

    Acetate/butyrate and carbohydrates can be transformed into ethanol/butanol by Clostridium strains (ABE fermenattion), e.g. with mixed cultures as well. You can find and doiwnload a review (book chapter) about ABE fermentation on my RG page. IF I remember well, an USA group used mixed bacteria strains to increase the yield of alcohols, but the same bacteria can metabolize all three kind of substrate in ABE fermentation.

  • Remilien Emmanuel asked a question in Business:
    What about GEM approach? How to use it with Motivation Theory?

    I´m studying Motivation as an element in the venture of rural woman. As divided by some authors we have three dimensions of motivation "Intrinsic, Goal, and Extrinsic". 

    Extrinsic is the situation (displacement by Shapero) that people have to start the business like unemployment, job dissatisfaction, etc.

    Goal is what people want to archieve by starting the business. and finally intrinsic motivation help nacent entrepreneur to keep on until they start and it help business manager to not give up.

    Where should i use GEM approach? "NECESSITY vs OPPORTUNITY. are they goal or displacement?


  • Why did myTiO2 target change color after pulse laser ablation?

    i have deposited TiO2 with pulse laser deposition system at room temperature and 10 e -6 pressure infact thin film was fabricated but the target has changed colour from white to steel grey where laser was incident.Can anyone suggest the reason for it? the laser wavelength was 532. 

    Waqee ur Rehman · International Islamic University, Islamabad

    FTIR will give you peaks on certain wavelength, which can vary with standard data, you can compare them

  • Vivi Alviani added an answer in BLAST Analysis:
    How do I know if our DNA sequence has the same species with the DNA sequence retrieved from gene bank by BLAST?

    how to know that our DNA sequence has the same species with one of DNA sequence from genebank in blast analysis? if the answer is the query cover and identity value must be 99% or more. then i have another question, i have a problem with my BLAST result. in top fifty species which have the closed homology with my DNA sequences are contain three different species name who has the same 99% identity value and query cover. so, which one i should choose as the same species with my DNA sequence? why it's happen? and this i show you my Blast result... >

    Vivi Alviani · Gadjah Mada University

    mr. leopordo: thanks for the suggestion.

    Mr. Chandra : thank you for the information. can you give me the new report article?

    thank you for the suggestion, yes, actually, in this research i'm not only doing molecular identification, but i also doing morphological identification.

    actually that blast result is DNA sequen from the mating product of fruit fly between B. carambolae and papayae (the fruit flies has the mix morphology between both of them). do you have an article journal which explain about it? the author is Ebina n' ohto. they have research about mating product between car n' pap.
    do you have that article?

  • László Kótai added an answer in Vanadium:
    How can magnetic succeptibily confirm the oxidation states of vanadium in an inorganic compound?

    how can we assume that there are two oxydation states or just one 

    László Kótai · Hungarian Academy of Sciences

    The magnetic susceptibility measurement will give information about number of unpaired electrons, and startiung from elementary analysis and the number of unpaired electrons youc an determine the valence.

  • Hao Chen added an answer in Cell Death:
    Does anyone have experience in Calu3 cell culture?

    I started culturing Calu3 cells recently and I'm wondering if it is normal for this cell line that there's quite a lot of cell death (or at least, floating cells which I assume are dead cells). Cells grow 1:4 per week in DMEM/F12 w/ Glutamax 10% FCS, 1x NEAA, pen/strep. 

    Hao Chen · The Chinese University of Hong Kong

    Good luck! 

  • Please can someone recommend online articles in relation to application of strategic management and performance of tertiary institutions?

    Strategic Management in Tertiary Institutions

    Following articles may be useful to you:

    Chavan, M., Bowden-Everson, J., Lundmark, E. and Zwar, J. (2014) "Exploring the drivers of service quality perceptions in the tertiary education sector: Comparing domestic Australian and international Asian students", Journal of International Education in Business, Vol. 7 No. 2, pp.150 - 180

    Warning, S. (2004) "Performance Differences in German Higher Education: Empirical Analysis of Strategic Groups", Review of Industrial Organization, Vol. 24 No. 4, pp 393-408

    Pires da Rosa, M.J., Saraiva, P.M. and Diz, H. (2001) "The development of an Excellence Model for Portuguese higher education institutions", Total Quality Management, Vol.12 No.7/8

    De Boer, H.F., Enders, J. and Leisyte, L. (2007), "Public sector reform in dutch higher education: the organizational transformation of the university".  Public Administration, 85: 27–46.

  • Are xylol and xylene one and the same?

    One of my friends looking to purchase xylol for his research then he asked me about this. I have been looking for xylol and the only results that came close to having is xylene.

    According to Wikipedia, xylol is similar to xylene but I could not confirm the CAS numbers are similar.

    Can someone confirm this? Are they same?

  • E. I. L. Silva added an answer in Cyanobacteria:
    Any suggestion for a guide for identification and characterization of cyanobacteria?

    Does anyone know a good guide that helps with identifying cyanobacteria from microscopical photographs?

    I'm looking for something that tells us what to look for and gives examples, such as cell shape, colour, morphological aspects, type of division etc and what else to look for and which cyanobacterial strain is resembled the closest.

    Thanks and regards

    E. I. L. Silva · Water Resources Science and Technology

     I also recommend Komárek & Anagnostidis  as   most recent and complete guide 

    . Pl contact Linda Lawton for more details.

  • How do I prepare a solution of H2PtCl6 from PtCl4?

    This can be done by dissolving PtCl4 into HCl, but if I want 5mM of H2PtCl6, then what amounts of PtCl4 and HCl should I use?

    László Kótai · Hungarian Academy of Sciences

    Both of comments are correct,  I would be one remark only, 10 mM HCl will not probably be enough to dissolve PtCl4 without residue due to hydrolysis. If you want 5 mM H2PtCl6, you have to dissolve really 5 mM PtCl4 in HCl soln. (more than 10 mM) enough to dissolve it completely.  Excess of HCl needs to stabilize the H2PtCl6 because of acidic nature (hydrolysis) of H2PtCl6.

  • Andrea Di Muro asked a question in Eruptions:
    What causes iridescence of basaltic glass surfaces?

    Iridescence is very often observed on the glassy surface of freshly erupted basaltic tephra like those erupted by Piton de la Fournaise volcano;

    On one side, it disappears quickly on samples collected soon after an eruption; on the other sides, it can be observed on clasts erupted centuries ago; multiple physico-chemical processes are possibly responsible of this intriguing phenomenon (chemical attack by acid gases; thin film effects; microvesicularity; density contrasts; quench rate etc); Better understanding that might help making a more quantitative link with fragmentation processes and eruptive dynamics;
    Is anyone aware of recent or old studies which could help in understanding the appearance and change of iridescence on basaltic glass surfaces? Thanks in advance,

    Best, Andrea

  • Kevin Chin asked a question in Text Categorization:
    Where Can I get the dataset Reuters-21578 ModApte for text categorization ?

    Where Can I get the dataset Reuters-21578 ModApte of the version with 7770 training documents and 3019 test documents, where each document is stored as a separate file ? And  if you have ever used the dataset, please tell me where to get your preprocessed dataset and your publications. Thank you very much. 

  • How to use a compounds extract from a pharmaceutical pill?

    I would like to know if someone know the correct approach on how to validate the purity of an extracted compound from a pharmaceutical pill. I.e.,  I want to develop a method to analyse a certain compound (ex. caffeine) but the analytical standard is very expensive. But I have a box of pharmaceutical pills with that have that compound in its composition. What i want to know is how do I extract that compound (ex. caffeine) from the pill and can I use it as an analytical standard to my method development? I intend to to a methanolic extraction, do a preparative analysis via HPLC, and a confirmation via analytical HPLC (for compound purity) and MS and NRM for compound identification. It it possible to do this and is it acceptable for method development and validation?

    Thank you for your attention and sorry for this long post.

    Guillermo R. Labadie · National Scientific and Technical Research Council

    Of course is possible. You can use an adequate solvent (depending of the polarity of the compound) concentrate and purifiy by recrystallization if you have enought material and prep HPLC. The more important part is how good is your purification method. Analytical HPLC will give you the purity data that you need, and you can repeat the purification until you reach the analytical standard purity. NMR, and MS will garantee the identity, HPLC purity of the compound. 

  • Paul L. Broughton added an answer in Karst Topography:
    Can anyone recommend papers on the morphology/ontogeny of speleothems?
    I am interested in understanding the ontogeny (major and minor structures) of the speleothems.
    Paul L. Broughton · Chevron Canada Resources

    You may want to review:

    Alan C. Kendall and Paul L. Broughton, 1977,Discussion: calcite and aragonite fabrics, Carlsbad Caverns: by R. L. Folk and Riccardo Assereto,  Journal of Sedimentary Petrology, volume 46, pages 486-496: Journal of Sedimentary Petrology, volume 47, pages 1397-1400. (renamed Journal of Sedimentary Research)

    Alan C. Kendall and Paul L. Broughton, 1978, Origin of fabrics in speleothems composed of columnar calcite crystals. Journal of Sedimentary Petrology, volume 48, number 2, pages 519-538. (renamed Journal of Sedimentary Research)

    Paul L. Broughton, 1983, Lattice deformation and curvature in stalactitic carbonate.International Journal of Speleology, volume 13, number 1-4, pages 19-30.

    Paul L. Broughton, 1983, Environmental implications of competitive growth fabrics in stalactitic carbonate. International Journal of Speleology, volume 13, number 1-4, pages 31-41.

    Paul L. Broughton, 1983, Secondary origin of the radial fabric in stalactitic carbonate.International Journal of Speleology, volume 13, number 1-4, pages 43-66.doi: org/10.5038/1827-806X.13.1.4

  • E. I. L. Silva added an answer in CCA:
    What is the best way to identify the most dominant species based on their abundance?

    Hi there... i do have a set of phytoplankton abundance data (attached) and i would like to do some statistical analysis. in most literature i have seen that researchers usually report the most dominant species when they present their results. i got little bit confused because i really don't know what is the scientific approach that i should use to select the most dominant species from my data set. to make it little bit clear, if i want to do CCA analysis, most of the literature i fallow present only the dominant species in the plot (they did not include all the rare observed species).   many thanks in advance

    E. I. L. Silva · Water Resources Science and Technology

    Your data set looks huge and many of them are  rare species. Environmental variabilities  and  physical features  among the sites are not given. First,  compartmentalize into  presence or absence of  species in different sites. Eliminate the rare species considering appropriate number of sites  as a percentage.  I think , better to  calculate the  species dominance for  each genera  to get a clear picture  since environmental requirements of different species may  different. . 

  • Noor Ul Afsar added an answer in Salicylamides:
    Why am I not getting my product when synthesizing N-Benzyl salicylamide?

    Salicylic acid 0.01 moles benzylamine 0.01moles MeB(OH)2 0.1mol 5 ml oxylene. Heated at 130 C but it fails. Please suggest any suitable method to get my product.

    Noor Ul Afsar · University of Science and Technology of China

    Because for further reaction I would need OH of Salicylic acid for the ligand preparation.... 

  • László Kótai added an answer in Crystal:
    Is a crystalline phase of sodium disilicate described in litterature?

    Many papers deal with the growth of a sodium disilicate crystal (Na_2 Si_2 O_5), but they do not explicitly give the crystal strucutre. I would be interrest to run molecular dynamic simulation of this kind of cristalline compound, but I need a starting point: the cristalline structure.

    László Kótai · Hungarian Academy of Sciences

    Yes, it is. There are many modifications with known structures. You can find the details of one modification in the following paper (and some information about the others):

    Solid State Sciences  5(3),  2003,  473-480
    Hydrothermal synthesis and structural characterization of κ-Na2Si2O5 and Na1.84K0.16Si2O5

    Rakić, S.a, Kahlenberg, V.b , Schmidt, B.C.c

    ingle crystals of a new sodium disilicate modification labeled κ-Na2Si2O5 have been prepared from the hydrothermal crystallization of a glass at 700 °C and 3 kbar. The structure has been solved and refined to a residual of R(|F|) = 0.035 for 750 independent observed reflections. The compound is orthorhombic with space group Pn21a (a = 8.128(1) Å, b = 4.8322(8) Å, c = 11.977(3) Å, V = 470.4(3) Å3, Z = 4, Dx = 2.57 g/cm3, μ(Mo Kα) = 0.87 mm-1) and belongs to the group of single layer silicates. Individual sheets can be described as being built by the condensation of zweier single chains of SiO4-tetrahedra parallel to the b-axis or, alternatively, by condensation of vierer single chains parallel to the a-axis. The layers contain six-membered rings in UDUDUD conformation. The stacking of the layers parallel to the c-axis results in a three-dimensional structure in which the alkali cations reside on two crystallographically independent sites (M(1) and M(2)) between the layers for charge compensation. The geometrical and topological features of the single tetrahedral sheets in κ- Na2Si2O5 are almost identical to those observed in β- and C-Na2Si2O5. Differences between the structures can be attributed to different ways of stacking of adjacent sheets and are discussed in detail. Small amounts of potassium can be substituted for sodium without changing the structure type. At slightly different synthesis conditions (600 °C, 1 kbar) we obtained an isostructural mixed alkali disilicate with composition Na1.84K0.16Si2O5 (a = 8.172(2) Å, b = 4.849(1) Å, c = 12.078(3) Å, V = 478.6(3) Å3). The distribution of the alkali atoms among the two M(1) and M(2) positions shows a definite preference of the larger potassium for the M(1) site; the M(2) site is K-free.

  • What are the research directions in quantum biology?

    Quantum biology refers to applications of quantum mechanics to biological objects and problems (Wikipedia). Erwin Schrödinger, one of the founders of quantum theory in physics, was also one of the first scientists to suggest a study of quantum biology in his 1944 book What Is Life? (see link). Many biological processes involve the conversion of energy into forms that are usable for chemical transformations and are quantum mechanical in nature (Wikipedia). A recent book Life on the Edge: The Coming of Age of Quantum Biology by Jim Al-Khalili and Johnjoe McFadden is a good reference on Quantum Biology. As this is a deep theory, the space here is not enough to write all in detail about quantum biology. I welcome views on quantum biology and especially the research directions in this area. Thanks!

    Sundarapandian Vaidyanathan · Vel Tech - Technical University

    Some research has shown that the classical music of Wolfgang Amadeus Mozart has helped the pregnant women.

    To quote the link enclosed, "Many music researchers conclude the classical music Mozart composed triggers a logical progression of musical “pathways” easily mapped in the brain that somehow has listeners or musicians, be they adults, children or babies have an enhanced mental functioning. The type of intelligence researchers refer to is called spatial temporal reasoning."

    I like Bach's classical music more as I am a Baroque fan. Mozart is also great!

  • Could anyone suggest why I encounter 'Unknown command line parameter definition' error when including ramachandran restraints in phenix.refine?


    I tried to refine a model from xray data using phenix.refine including a Ramachandran_restraints = True command line. It however turns out with an 'Unknown command line parameter definition' error. 

    It seems to me ramachandran restraints is more than common in refinement. Would it be that my phenix.refine has somehow corrupted? If so how can I reinstate this operation without re-installing the whole phenix?

    Thanks in advance!

    Thomas Charles Terwilliger · Los Alamos National Laboratory

    Hi Sam, try this:

    phenix.refine --show_defaults=3

    which should list (among other options):

       ramachandran_restraints = False

    If it doesn't, then you might need a newer version of Phenix to use these.

    However...using Ramachandran restraints is generally not recommended as there are not very many situations where they improve your structure (they are best for maintaining helices if they start out very good).

    -Tom T

  • Simon Wollwage added an answer in Wikipedia:
    How I can find path length between two words in Wiktionary or Wikipedia?

    i want to find shortest path length  and path depth between any two words using Wikipedia or Wiktionary. can anyone help me in this regard.

    Simon Wollwage · RWTH Aachen University

    Retrieve all links on the page for the first word, then examine all these pages. Repeat the same process. Essentially what you're looking for (if I understand you correctly), it a breadth first search.

  • Could you recommend some papers on the relationship between fiscal deficits and inflation?

    I want to explore this topic for Central America and I'm looking for some references.

    There are plenty of articles discussing the influence of fiscal deficits on inflation. Here are some most used references:

    1. "Fiscal deficits and inflation" by Catão and Terrones, published in Journal of Monetary Economics.

    2. "Fiscal Deficits, Exchange Rate Crises and Inflation" by
    Sweder van Wijnbergen published in Review of Economic Studies.

    3. "Inflation implications of rising government debt" by Giannitsarou and Scott (http://www.nber.org/chapters/c7040.pdf)

    4. "How did structural reform influence inflation in transition economies?" by Barlow published in Economic Systems

  • Paul L. Broughton added an answer in Speleogenesis:
    Is there an updated list of cave minerals?
    Is there an updated list of cave minerals in the world? According to the excellent book Cave Minerals of the World by Carol Hill and Paolo Forti (1997) there was 255 minerals found in caves. Do you maybe know the number today?
    Paul L. Broughton · Chevron Canada Resources

    You could review the following for additional data:

    Paul L. Broughton, 1971, Übersicht der in Tropfsteinen bekanntgewordenen Minerale. Die Hӧhle, Zeitschrift für Karst-und Hӧhlenkunde, volume 22, number 3, pages 81-82.

    Paul L. Broughton, 1971, Origin and distribution of mineral species in limestone caves. Earth Science Journal (New Zealand), volume 5, number 1, pages 36-43.

    Paul L. Broughton, 1972, Monohydrocalcite in speleothems: an alternative interpretation. Contributions to Mineralogy and Petrology, volume 36, number 2, pages 171-174.

    Paul L. Broughton, 1972, Secondary mineralization in the cavern environment. Studies in Speleology, volume 2, part 5, pages 191-207. Published by William Pengelly Cave Studies Trust, Buckfastleigh, England

    Paul L. Broughton, 1973, Replacement of gypsum by length-slow chalcedony in the karst subsurface. Caves and Karst: Research in Speleology, volume 15, number 3, pages 21-23. (published by Cave Research Associates, ceased publication in 1973)

    Paul L. Broughton, 1974, Protodolomite and hydromagnesite in cave deposits of Sumidero Tenejapa, Chiapas, Mexico. Boletín de la Sociedad Venezolana de Éspéleología, volume 5, number 1, pages 19-25.