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  • Roman Kubrin added an answer in Pvd Coating:
    Could anyone tell me please, how could I measure porosity of PVD coatings?

    I have several coatings and would like to compare them. I choose porosity as the main properties for comparing. But how could I measure porosity of PVD coatings? 

    Thank you in advance

    Roman Kubrin · Empa - Swiss Federal Laboratories for Materials Science and Technology

    Agree with Daniel, we used fitted ellipsometrical data and the theoretical refractive index to estimate porosity by using Yoldas mixing rule. See for example Tamar et al., Sol.Energy Mater. Sol. Cells 130 (2014) 246-256

  • How do I perform discriminant analysis with 16 dependent variables?

    Discriminant analysis on SPSS is limited to 12 dependent variables. However, I need 16 for a study I am conducting. Does anyone have a work-around for this or know of a package that can analyse 16 dichotomous variables?

    John Ireland · Canadian University of Dubai

    So far, I have two answers telling me not to do discriminant analysis.

    Could someone answer my question?

  • Mustafa Çiçekler asked a question in Parameters:
    How can I determine deinking efficiency?

    I want to know how to determine deinking efficiency? Which parameters i must know

  • Jakub Piekart asked a question in Ionic Liquids:
    Can ferrocene be used as solvatochromic probe?

    I want to compare polarities of two ionic liquid pools in ionic liquid microemulsions.

  • What is the critical force between Cooper-pairs?

    Cooper pairs are assumed to be paired due to phonon-electron interaction. In Josephson junction a critical current is developed with zero voltage. In a recent work I have found that there associated with this critical current a critical force that is associated with critical pow P_c=mu_0 c (I_0^2). This power can be seen as the ordinary electric power dissipated by a vacuum resistance, Z_0=mu_0c. I wonder whether this critical force could be related to force between two Cooper-pairs in the two sides of the junctions or not. Its value for a microampere current is 10^(-10) N which amounts to a force between two pairs at a distance of a few nanometer....Can any one help me what this force could represent?

    Thank you in advance!

    Arbab I. Arbab · University of Khartoum

    Dear Gupta

    The thickness of the insulator is some a few nanometers.

  • How much methane than can be produced per 1 kg of cow manure using anaerobic digestion?

    We have small project to generate methane from cow manure.

  • Iwant to know about groundwater modelling simulation if some one do research about this field?

    I think hydro geologist can help me about this research

    Zhonghe Pang · Chinese Academy of Sciences

    Groundwater modeling is quantitative representation of groundwater system at various scales, from well bore scale, to well field scale, and to aquifer scales. A numerical model is usually built upon a hydrgeological conceptual model that is set up based geoscientific investigations using geological, geochemical and geophycisal methods.

  • Aneesh Raveendran added an answer in Chips:
    What are the research chips available in the market?

    To do a post-silicon validation/verification for finding functional bugs, which type of research chip can be used? 

    Aneesh Raveendran · Centre for Development of Advanced Computing, Bangalore

    Hai, Ravikumar

      Your are correct. Try to get collaborations from some foreign universities like UCB or MIT. They are giving chip for post silicon validation. 

    I am working in india chip program for developing a processor, yet no chip is ready for post silicon vaildation

  • Freddy Dardenne added an answer in Bacteria:
    Is there a protocol to detect bacterial colonies expressing agarase from an initial 10 ml culture of E coli sample at around 106 cfu/ml?

    To identify agarase-expressing bacteria within a mixture of Escherichi coli strains, samples of E. coli were serially diluted and spread over LB (Luria-Bertani) agar plates. After overnight growth, zones of hydrolysis surrounding individual colonies were stained using potassium iodide, at a final concentration of 1 mM.

    Urgently, thanks.

    Freddy Dardenne · University of Antwerp

    Water will kill most of the bacteria because of osmotic inbalance. You can use sterile physiological water or peptone water.

  • Gianpiero Colonna added an answer in Chemical Bonds:
    Can a forward reaction rate of chemical reaction be calculated from Gibb's energies of substrates?

    The idea is to divide the equation of equilibrated chemical reaction into forward and backward part. The equation dG = - T R ln(kf/kb) into dGp - dGs = T R ln(kb) - T R ln(kf), where dG is Gibb’s energy of reaction, dGs is Gibb’s energy of substrates, dGp is Gibb’s energy of products, T temperature, R gas constant, kf forward rate coefficient, kb backward rate coefficient.
    Looking at this form I suggest the following equation:
    B + dGs = T R ln(kf), where B is some constant (may be dependent on type of the chemical bond).
    Is the equation correct? What should be behind the parameter B? For which chemical reactions has B the same value?

    Gianpiero Colonna · National Research Council

    What I think is that it is not possible at all to find the reaction rate from thermodynamic quantities.

    An example:

    Two reactions with the same DG do not have the same velocity.

    Consider the N2 dissociation. It happens with the following reaction


    Now the rate coefficient depends on X. You can find many references in literature about these rates.

    Another example, Methane combustion. At room temperature the rate is 0. DG is high.

    Thermodynamic quantities tell you how far you are from the equilibrium, not if the equilibrium state can be reached and, if yes, at what speed.

    The Arrhenius law includes some dynamical parameters such as activation energy, that takes into account the height  of the barrier (not a thermodynamic function) and a power constant to consider the slope of the potential energy surface.

  • Tadele Akeba asked a question in LaTeX:
    How to import large data tables into LaTeX?

    I'm wondering whether anybody has experience with  importing large multicolumn and multi row data to latex document?

  • [Download] Genetic control of midbrain dopaminergic neuron development?

    I cannot access to this article. Please give me a hand on it, Thanks!

    Prashanth Suravajhala · University of Copenhagen

    I sent the one. 

  • Luca Gelisio added an answer in Stress Analysis:
    How to do residual stress analysis of a solid component using X-ray diffraction ?

    Whether it is a non-destructive method or a destructive one ?

    Luca Gelisio · Università degli Studi di Trento

    In an extremely simplified way, you compute residual stress by measuring the strain in the crystal lattice, i.e. the change in interplanar separation (d) compared to a reference value. The stress is then obtained assuming linear elastic deformations.
    It is a non-destructive method (but optionally you can continuously remove material so to obtain a stress profile as a function of the distance from the surface of the sample) and the value obtained is an average over a volume defined by the irradiated area and the penetration depth.
    A superb source is the book by I.C. Noyan and J.B. Cohen, "Residual Stress: Measurement by Diffraction and Interpretation".

  • Martin Larcher asked a question in BLAST:
    Which JWL parameters are you using for TNT?

    I'm just wondering what JWL parameters are the appropriate ones for TNT? Especially the internal energy (per unit volume or per unit mass) varies a lot in literature. You can find values for the energy per unit volume between 6 and 7.1. By using these values you find also a significant difference in the blast wave results.

  • It is possible to have an activated carbon with pHpzc = 7.5 despite the Boehm titration indicate 1.5 mmol/g acidic groups and 0.5 mmol/g basic groups?

    I have determined a neutral value for the pHpzc of an activated carbon. By Boehm titration the results indicates that the surface of the activated carbon contains more acidic oxygenated groups than the basic groups. These results are in contradiction with the pHpzc value? If yes, why, if not, why?

    Daniela Popovici · Petroleum - Gas University of Ploiesti

    Thank you for your answer, Nicholas. You confirm my assumption . In fact, I determined the nature of the acidic groups and I found 1.27 of carboxylic groups, 0.055 of lactonic groups and 0.22 phenolic groups (from a total of 1.545 acidic groups). As basic groups I found only amines (by IR spectroscopy). 

  • Adil H.H. Bashir added an answer in Disease:
    Large collection of disease-specific case reports versus the population... Do they approximate each other?

    I realize this question may sound weird (to say the least)... but I was always wondering if one took all the reported literature cases for a specific disorder / disease (assuming that there would be 1,000's of them) -- would the collected sample actually approach the true disease population? Would there still be significant reporting bias? What do you think?

    Adil H.H. Bashir · University of Khartoum

    Case reports are presented to clinicians accidentally, sometimes could be reported before with another diagnosis, we had seen such conditions before, so case reports represents itself, not the prevalence of the disease.

  • Idris Akyuz added an answer in Spray Pyrolysis:
    SnO2 thin film on ITO Sheet?

    I aim to deposit Sno2 thin film on ITO Substrate using spray pyrolysis. What are the vital points I should take into consideration?

    Idris Akyuz · Eskisehir Osmangazi University

    Be careful when using SnCl2 in spraying solution. If you try to use water as solvent, watch out the possible sedimentation in the pipes. I suggest to add ethanol into the solvent to prevent sedimentation. Substrate temperatures above 350 °C needed for better crystallization.

  • Do you have any references with regard to this topic: health, safety, and environment in water and wastewater engineering?

    I am looking for books that specifically discuss this matter.Any suggestions?

  • Bhaskar Bhaduri asked a question in Nanoparticles:
    How does Ni nanoparticle interact with carbon monooxide?

    I would like to study the interaction of Ni nanoparticles with CO. Kindly suggest me the mechanistic steps involved in the interaction of  Ni with CO....Thanks in advance...

  • Vipul Dabhi added an answer in MATLAB:
    Why are the weights different in each running after convergence?

    I am using a 2 layers (one hidden layer ) Neural Networks based classifier to run a classification for my data (images) and use back propagation algorithm.

    the networks works well and can classify  with more than 90% of accuracy . But the shape of weights in hidden layer are different by running every time. I am using Matlab imagesc function to  visualize the  weights.

    Vipul Dabhi · Dharmsinh Desai University

    I completely agree with the answer given by James Dominic O'Shea that weights are initialized randomly each time you start learning phase in ANN. These randomly assigned weights lead to different convergence states and that is why we get different classification/prediction accuracy every time.

  • Kwok-On Lai added an answer in Plasmid Cloning:
    Does anyone use the CRISPR-Cas9 knockout plasmids from Santa Cruz?

    Has anyone tried to amplify the plasmid by transformation into E.coli? The amount of plasmid for each vial is only 20ug, and it does not have the antibiotic selection information on the spec sheet of the plasmid for amplification into competent cells.

    Thank you!

    Kwok-On Lai · The University of Hong Kong

    Thank you very much, Christian!

  • Ng Kei Hoa added an answer in Fuel Cells:
    What are the minimum conditions to be fulfilled by a ceramic to be tagged as potential candidate for SOLID OXIDE FUEL CELL?

    I know conductivity variation is an important parameter and it exclude electronic contribution(correct me if i am wrong). But want to know, other parameter/properties, that should be possessed by such materials. And experimental technique that  can verify its candidature for SOFC?

    Ng Kei Hoa · Universiti Tun Hussein Onn Malaysia


    I am also a newbie for SOFC. It is great to find someone that is in this research field here. Depending on the component that you are investigating, anode, cathode, electrolyte or the interconnecting materials. They require different types of properties.

    Generally, electronic contribution is important but depending on which components that you are focusing. Such as anode, main material should be high catalytic and high dissolution when react with H2 or any other gasses. The material should be also metallic for electron conduction so that it completes the circuit back to cathode. Electrolytes needs higher ionic conduction to transfer oxide ion to anode from cathode . Though some of the materials possess mixed ionic electronic conductivity, it depends on which type of component that u are concern. And many studies regarding the different types of parameters and operating condition. Other that that, conductivity, impedance testing, single cell testing will be the main research interest nowadays. This field is seriously wide and many interesting knowledge can be explored. 

  • Avacaritei Daniel added an answer in Biomass:
    Short Rotation Coppice Willow Biomass potential in Finland?

    Does anybody know where i can find relevant articles for willow biomass production in Finland from 2010-2014. Thanks

    Avacaritei Daniel · Stefan cel Mare University of Suceava

     You can followers, this similary article. Nord-Larsen, Thomas, Lisbeth Sevel, and Karsten Raulund-Rasmussen. "Commercially Grown Short Rotation Coppice Willow in Denmark: Biomass Production and Factors Affecting Production." BioEnergy Research (2014): 1-15.

  • Andreas Kunzmann added an answer in Aquatic Ecology:
    Does anyone have experiences (good or bad) with "EthovisionXT" software?
    We are planning to buy a new licence for Ethovision from Noldus, but we are not sure about its practical use for crayfish and fish.
    Andreas Kunzmann · Leibniz Center for Tropical Marine Ecology

    It is expensive, but I think worth it. In our case the best was the local agent, who also gave a thorough introduction and was still available for questions etc. long after. So he really KNEW the program in and out.

    Ask your country representative whether they are able to provide this service.

  • How do holes recombine with electrons in single carrier type steady state conduction?

    Suppose that e-h pairs are generated on anode surface of an insulator by surface absorption of light. some of the electrons recombine there in surface very shortly. The remaining electrons are pulled out of the insulator by the positive anode. Now the remaining holes start their journey towards cathode.

    Books and papers say, the holes recombine with electrons/get trapped in defects and so their density decreases as they move forward. In a paper "High Field Effects in Photoconducitng Cadmium Sulfide" by Many, the hole density in steady state is given as  


    Which clearly shows that the hole density decreases exponentially with the thickness (x) of the insulator.

    1. The situation becomes confusing to me (probably I am not thinking correctly) when the cathode can not inject electrons into conduction band. How do the moving holes recombine with electrons in the middle of the insulator (there are no free electrons in CB to recombine with) and so they decrease with distance?
    2. I can understand in case of transient period before establishing the steady state, that the holes might get trapped in traps and so they decrease with distance. However, when they maintain a dynamic equilibrium of trapping and detraping in steady state, how do the holes decrease in numbers? (Seems like there are infinite traps and so the injected holes keep filling the trap without detraping.)
    3. Suppose that the cathode inject electrons to move through conduction band allowing holes to recombine them. But now, is it purely a hole current ? is not there electron current contribution ?
    Gyanendra Bhattarai · University of Missouri - Kansas City

    Thank you Petr Viscor for your time and answering my question.

    Regarding my question, I want to be little more clear. Though it is quite long, I hope you take a look.

    1.  In the paper I cited above, "High field effects in Photoconducting CdS"  Many talks about the transient current induced (displacement current) by the photogenerated charge moving inside CdS crystal. Clearly, they can not make steady state photocurrent as the crystal is not connected electrically. They are using mica spacers to couple the crystal capacitively. I believe the displacement current is same as the current explained by shockley-ramo theorem.

    2. In one case, they use the approximation of surface absorption of light to create holes (they irradiate +ve contact with light so holes gererated migrate towards negative contact). So in ideal case, the mechanism of decrease of carriers as they move forward is because of trapping. The exponential decrease is not related to exponential attenuation of light intensity. The paper assumes that the photogenerated carriers are low enough to believe the electric field inside is uniform (not affected by generated charges)

    Below is my understanding and confusion.


    Suppose we have direct electrical contact say blocking so we can measure steady state photocurrent. In steady state, I think the displacement current contribution vanishes and the continuity equation is explained only by drift current. If there are traps, I think two possibilities:

    a. The traps are filled uniformly spatially and so the electric field remains uniform. The drifting carrier concentration remains uniform and so continuity equation is hold.

    b. Since carriers are generated near anode, they are trapped more in anode region and so the carrier density drops exponentially along distance. In this case, for the continuity equation to hold, the space charge is created and the electric field will be non uniform (like in space charge limited current.)

    However in both cases, the total current is because of drift current and the total current is given by J = e*p(C)*mu*E(C). where p(C) is density of holes collected at cathode and E(C) is electric field at cathode. I don't think we need to integrate the charge carriers entire sample to get the current.


    There are many papers describing  Hecht analysis. Most of them cite Many's paper. Though Many's paper describes transient current, other authors use the same mathematics for steady state. Though they find p(z), E(z) for every z, they  integrate  e*p(z)*mu*E(z) over the entire length and divide by the volume of sample to get the current. I am not convinced by this integration because once one knows p(z), E(z), the current is just J =  e* p(z) *mu* E(z) = e* p(C)*mu* E(C). 

    In short, I can say that, I don't understand how Shockley-Ramo theorem is used in steady state. I don't see its applicability as there is no displacement current unless there are electrons inside the material so the charge carriers disappear which then requires S-R theorem to calculate total current.

  • Abdul Khaleque added an answer in Pediatrics:
    Can anyone provide a reference for ITP in pediatric age group?

    Do you have any new pathogenesis of ITP in pediatric age group.

    Abdul Khaleque · Bangabandhu Sheikh Mujib Medical University

    In approximately 60 percent of cases, antibodies against platelets can be detected. Most often these antibodies are against platelet membrane glycoproteins IIb-IIIa or Ib-IX, and are of the immunoglobulin G (IgG) type. Some renowned research, the Harrington–Hollingsworth experiment, established the immune pathogenesis of ITP.

    The coating of platelets with IgG renders them susceptible to opsonization and phagocytosis by splenic macrophages, as well by Kupffer cells in the liver. The IgG autoantibodies are also thought to damage megakaryocytes, the precursor cells to platelets, although this is believed to contribute only slightly to the decrease in platelet numbers. Recent research now indicates that impaired production of the glycoprotein hormone thrombopoietin, which is the stimulant for platelet production, may be a contributing factor to the reduction in circulating platelets. This observation has led to the development of a class of ITP-targeted drugs referred to as thrombopoietin receptor agonists.

    The stimulus for auto-antibody production in ITP is probably abnormal T cell activity.

  • Qijin Chi added an answer in Potentiostat:
    Can anyone help me to find a specific capacitance of my Sample using Cyclic Voltammetry in GAMRY 1000 Potentiostat?


    Qijin Chi · Technical University of Denmark

    It is not clear enough with your question. You might specify your sample and what you have done. You can caculate the specific capacitance of specific materials from their cyclic voltammograms, charge-discharge curves or electrochemical impedance Spectra.  The estimate methods are well described in Electrochemical taxtbooks or many literatures.

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

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

    Ramona Khanum · International Medical University (IMU)

    Hello. I'm not familiar with veterinary medicine but would a central venous catheter (CVC) - used for critical care patients work for your use? They have a range of gauge sizes and number of lumens. B Braun is one manufacturer I have purchased CVCs from, for research use. 

  • What would be a first (reliable) apoptosis assay before validating by annexin V / PI staining?

    We observed some dose dependent cell death in Hela cells after treatment with a potential drug we developed. We want to know what kind of cell death it induces, but without having to dive right into elaborate assays such as FACS (as we need to screen multiple cancer lines to confirm). Thank you!

    -- Please suggest some assays (pros and cons): e.g. TUNNEL, WB for caspases, DNA fragmentation, some commercial kits (esp. if you have done or used!)