Q&A

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  • Matteo Galbiati added an answer in PECVD:
    How do you change the working pressure in a RF- PECVD system ?

    I want to deposit SiCN thin films at different working pressure. How I can change the working pressure?

    Matteo Galbiati · Micron Technology, Inc.

    Some more on NF3. NF3 is a standard clean gas in micronelectronic, moreover because it is less dangerous than CF4, both for environment and for humans. NF3 clean is generally done via a remote plasma clean, to improve NF3 dissociation efficiency, and it is useful a downstream plasma apparatus (DPA) to burn the residual powder.

    Nitride deposition produces a powder (white and easily washable in water)  that can accumulate in the vacuum pump systems. The DPA traps and vaporizes these residues: during deposition, it traps powder by a physical trap and it burns the trapped powder, during chamber clean.

    Better than with special oils, with such apparatus you can improve your pump life time and decrease foreline maintenance enhancing safety.

  • Fabrizio Donnarumma added an answer in LC-MS:
    What factors could be influencing the MS resolution response in LC-MS?

    I am doing some LC-MS analysis and I got well resolved peaks in the chromatogram with the UV-detector. However, the MS detector shows very poor resolution. How can I improve this? 

    Fabrizio Donnarumma · Louisiana State University

    Just to avoid confusion, the resolution you are talking about is NOT mass resolution, right? Are you running your sample through the UV detector and then into the MS?

    If your UV chromatogram displays well separated peaks  and your TIC (or BPC) is not, then I would suggest you follow Pavel indication. It really sounds like a connection problem.

    Remember that normally we do not couple UV and Mass Spec. Actually, we try to reduce as much as possible the distance between the column outlet and the ESI source of the mass analyzer.

  • Weiran Zheng added an answer in Microbiology:
    My sample of biologically synthesized nanoparticles is showing different morphology in non contact AFM as well as HRTEM - any thoughts?
    Both show difference in diameter and shape. Is there any explanation?
    Weiran Zheng · University of Oxford

    AFM and HRTEM are quite different method in telling the particle size and morphology.

    HRTEM would require high energy electron to measure, and this would normally cause high temperature at the observation area (about 200C), so it would be possible that your  sample is changing or has changed at the same time.

    AFM, on the other way, could only give you the surface structure of the sample. You can't see the particles underneath.

  • Cesar Ortiz Ledon added an answer in Nanoparticles:
    How can I calculate accuretely the concentration of Pt nanoparticles I synthesized size is 4 nm?

    My calculation tells me I supposed to have 1 micromolar but I dont I have try it several times and same problem I get about 40 nM of Pt nanoparticles

    Cesar Ortiz Ledon · New Mexico State University

    Yes, I will explain, my problem is that I synthesized the Pt nanoparticles by using NaBH4 method added dropwise, once I finish the synthesis based on number of atoms and amount of Pt I added and the mean size of the nanoparticle the calculated concentration is 1 micromolar, however when I start doing dilutions to get into a picomolar range I don't get adequate response instead when I used a nanomolar concentration it gives the right response.

  • Harshavardhan Jayakumar asked a question in Flying:
    How the structural rigidity is achieved in formation flying of satellites?

    Any reference or where i can get the control dynamic aspects of formation flying?

  • Arturo Geigel added an answer in Neural Networks:
    Can we extend the learning rate domain on Neural Network?

    Dear Researchers,

    I'm just wondering why we should ALWAYS use the learning rate on neural network between [0 1]? What's the benefit of using the learning rate between that domain?

    Can we extend the domain for getting bigger rate? For example [0 4]

    I've read about it but I'm not convinced so I would like to extend my understanding about this matter.

    Regards,

    Amirmohammad

    Arturo Geigel · Polytechnic University of Puerto Rico

    I will use Backpropagation as an example of  why the learning rate must be small(it is usually very small), since you are trying to minimize the error using the learning rate as steps. If for example you are trying to minimize the error in a parabola, the use of a large learning rate will accelerate convergence but at the same time you may overshoot your goal.

    That is the direct answer to your question, what I think your real question was is the weight initialization assignment of neural networks. Taking again Backpropagation neural networks, it was a topic of research a long time ago. To see some results of the learning parameters such as weight initialization take a look at some of the foundational papers such as:

    1) Thimm, G., & Fiesler, E. (1997). High-order and multilayer perceptron initialization. Neural Networks, IEEE Transactions on, 8(2), 349-359.

    2) Fahlman, S. E. (1988). An empirical study of learning speed in back-propagation networks.

    If you have other types of neural networks in mind let me know and we can discuss them

  • I. G. Richardson added an answer in Magnetics:
    Is there any database available for Magnetic clouds up to 2014?

    As I think only few papers  are available on this field also very few database I found which is also up to 1990 or 1995. Does someone know about these data or other available database or recent research on this topic.

    I. G. Richardson · University of Maryland, College Park

    Correction:  The on-line WIND magnetic cloud list (up to 2007) is again available, at   http://wind.nasa.gov/mfi/mag_cloud_pub1.html#table

  • How can I simulate progressive impact damage in composite material with Abaqus?
    I want to model low velocity impact damage in composite plates. I don't know anything about it. Could anyone help me? Tutorial, book or etc.
    Azzam Ahmed · Sudan University of Science and Technology

    Dear mohammad there some pdf files about abaqus hope it will useful for u .

  • Colina Dutta asked a question in Western Blot:
    Issues with Western Blot

    I am facing primarily 2 issues with Western Blot. Firstly, during the transfer process, lot of heat is getting generated that results in boiling I do put ice pack during the process but lately the heat is very high. I run at 100V for 1 hour.

    Secondly, my nitrocellulose membrane is turning pink after the transfer. I have no clue what might be the case.

  • Daniel Zhitnitsky asked a question in Protocols:
    Can anyone direct me to a proven-to-work protocol for generating chemically ultra-compatent E.coli cells?

    I've tried several methods: the Inoue et al. MnCl2 method, 0.1M CaCl2 method and MgCl2+CaCl2 method. I managed to get only about 10^5 efficiency.

    I need a proven method for 10^8 - 10^9 efficiency.

    Can anyone please help? 

  • Agniva Saha asked a question in RNAse:
    How can one determine if a cellular RNA is 5'capped or not?

    I am studying a novel transcript in yeast and  would like to know if my RNA has a 5'7mG cap. I have tried treating RNA with a commercial cap-dependent RNase (Terminator exonuclease/Xrn1) but it showed sporadic and non-specific activity resulting in degradation of several non-substrate transcripts. I am looking for an alternative method that is compatible with northern blotting or RT PCR like techniques. Thanks in advance.

  • What is the difference of sustainable watershed management in relation to integrated watershed management?

    I believe sustainable requires the interconnection of ecological with socio economic components of watersheds while integrated management refers only to water resources in relation to socioeconomic alike. is this true?

    Hugo Soplin · Universidad Nacional Agraria La Molina

    Thanks to Manfred . The thesis is an excellent source of information on the topic under discussion

  • Duke Bayar asked a question in Antigen Retrieval:
    What high background staining means in heat-retrieved paraffin sections?

    i'm staining for a double-staining of TnI and cleaved-caspase-3 in paraffin-embedded mouse heart sections. In negative where there's no primary, I see a great deal of background of the secondary for the caspase-3 (alexa 488). What can I do to get rid of this high background 2ndary staining? should i cook more or use different antigen retrieval solution?

    primaries: m-TnI and Rb-m Caspase-3

    secondaries: G-m Alexa 546 and G-Rb Alexa 488

  • Nicholas Peiper added an answer in Psychometrics:
    Have you done any psychometric evaluation of the K10 (Kessler Psychological Distress Scale)?

    I am particularly interested in research supporting its validity/reliability with adolescent nonclinical samples.

    Nicholas Peiper · REACH Evaluation

    We have addressed the dimensionality of the K6 in a population-based sample of students who completed a school survey. Based on our results, we confirmed the 1-factor solution (i.e., serious psychological distress [SPD]) and found that the validated cutoff can be used to create provisional prevalence estimates of 30-day SPD.

    Peiper, N., Clayton, R., Wilson, R., & Illback, R. (2014). The Performance of the K6 Scale in a Large School Sample. Psychological Assessment. doi: 10.1037/pas0000025

    Feel free to get in touch with me if you have any further questions, hope this helps!

  • What resources would provide a good overview for concepts in organizational development?
    I work part time as an organizational development consultant, working with companies to help them develop and maintain good working relationships and productive organizational cultures. I would like to extend my skills and knowledge base in this area. What are some recent or classic books or articles that you might suggest?
    Terri D. Egan · Pepperdine University

    In our MS in Organization Development program at Pepperdine University we assign Cummings and Worley's Organization Development & Change as our core text. It covers the classics in the field as well as the latest research. Includes some great cases. The authors are well respected academics and consultants. Pricey, but consider it a replacement for a small library of OD books. 

  • Matthew Marler added an answer in Actigraphy:
    What is the best method to understand sleep actigraphy in older people?

    I have completed a study with older adults in care homes monitoring sleep and light patterns using actigraphy. I have a mixed set of outputs - some with a regular sleep cycle and others more disrupted patterns. I'm trying to best understand sleep quality and the most relevant variables to extract from the software (Philips respironic actiwatch spectrum). I'm not sure if setting a custom interval would help best or if the pattern shown should determine how to look at the stats. Any thoughts of good references welcomed.

    Matthew Marler · Carnegie Mellon University

    This paper might help.  the paper illustrates the method for actigraphy measures in nursing home patients.  Some of the published applications are mentioned in the discussion section.

  • What are challenges involved in inter satellite communication link?

    why is it difficult to achieve and what are the criticalities  involved in it?

  • F. Leyvraz added an answer in Quantum Field Theory:
    Does quantum field theory resolve the measurement problem in quantum mechanics?

    Recently I read a paper titled "Quantum field theory solves the problem of the collapse of the wave function" by Alexey V. Melkikh (arXiv:1311.0205v1 -
    quant-ph). An earlier paper on the same topic is " Measurement problem in quantum mechanics" by Michael Danos & Tien D. Kieu (Int. J. Mod. Phys, vol-8, p-257, 1999). Both these papers claim that the measurement problem is completely resolved with in the framework of quantum field theory because it incorporates both the particle and wave aspects, while quantum mechanics deals only with the wave aspect. While the arguments in these papers are convincing, I would like to know the general consensus on this topic.

    F. Leyvraz · Universidad Nacional Autónoma de México

    We do not seem to see the same things in the same picture. I see fairly large gradients in the cloud (not comparing them to outside the cloud, I am just asking, are these gradients, and hence velocities, large enough to get some particles that originally were in the cloud, to outside the cloud. Once the particles get outside the cloud, they are subject, as you correctly point out, to huge gradients). Finally, I would argue that  the gradients inside the cloud at t_1 are larger  than at 2t_1, vindicating my assumption that the velocities inside the cloud actually diverge at t=0.

    I do not understand your objection. The continuity equation I use in qm does not involve operators, nor superposition, nor anything of the kind. It is a conservation law for the norm squared of the psi function, and the current, which is what enters in the divergence, is not an operator, but simply psi^* grad psi - psi (grad psi)^*. This is a simple *local* calculus identity and does not involve operators, superposition or the like. it merely states how much ``probability density'' escapes from an infinitesimal volume in terms of a local current.

    That the standard intepretation of qm gives to psi a meaning wholly different from that of a classical field is clear to me. I also believe this usual interpretation is rather more satisfactory than any other. But an interpretation like Bohm's may fail to satisfy my esthetic sense, as indeed it does, without being actually contradictory.

  • Can i use frozen(-80c) mouse epididymal adipose tissue to do Flow Cytometry ?

    we just want to do Flow cytometry in vivo, but  the mouse epididymal adipose tissue was frozen at -80C, can we do it? and how to make cell fluids?

    Julio Enrique Castañeda Delgado · Mexican Institute of Social Security

    Hello Hu Huan,

    If you didnt suspended your cells apropiatelly and preserved them by using DMSO, probably your  will not be able to use the tissue for Flow. Usually you disgregate the tissue by using collagenase or other enzymes and then resuspend them in RPMI, or other apropiate culture media with 10% DMSO before frezzing or FCS at 10% DMSO . Hope this helps

  • What are the pros and cons of using proteolytic enzymes vs. laser capture microdissection to separate/isolate cell populations from tissues?

    Given how easy it is to damage your cells of interest via overexposure to proteolytic enzymes (and the lack of a "catapult" mechanism to move your cells of interest to your desired container as seen in additional laser-based microdissection techniques), I am having trouble seeing the benefits of using proteolytic enzymes to separate a given cell population when laser capture microdissection remains a viable option.  

    Sabyasachi Biswas · Genentech

    Laser microdissection is clearly the superior method, however it has some serious drawbacks:

    1) It is a low throughput system. Large number of samples cannot be processed quickly at the same time.

    2) Yields are typically very low and depends on tissue type used. It is only recently that molecular biology techniques have allowed us to analyze such minute amounts of material, however most techniques like microarray still require microgram amounts of RNA which takes a long time to obtain through microdissection.

    3) Requires specialized equipment and supplies which are expensive.

    4) Requires well trained operators. In my experience dedicated laser microdissection core facilities are more useful instead of  keeping it as a part of a histopathology facility. Sadly that is not the case in most places.

    5) Requires optimized staining procedures which will not degrade target molecules, especially RNA. Unsuitable staining methods are the leading cause of degraded samples. 

    6) Dissociation techniques have been use for a much longer period of time and most people are more comfortable with it or prefer to go with the flow rather than try something new.

    A sad but true fact is that people usually opt for the easy way out. It is much easier to dissociate cells rather than microdissecting them. Take into account the fact that typically microdissecting an area of interest of say 1 square mm (1 million square microns)  can take between 20-60 mins, resulting in collecting about 3000-5000 cells which will yield 20-40ng RNA if you are lucky. Compare that with yields obtained from dissociated cells.

    As someone who manages an LCM Core facility I have seen users balk at the labor and time involved as well as the cost. However the most difficult thing to overcome is the unreasonable expectation. No, you will not be able to get 500µg of purified RNA for running your microarray from 24 samples within one week!

    Please note that the views expressed here are my own and is not meant to reflect that of my employers.

  • Jethro Betcke added an answer in Energy:
    Does anyone have experience with hybrid systems based on complementary energy resources?
    Have you analyzed hybrid systems whose energy resources could be considered complementary?

    It was a full complementarity? It was a partial complementarity?

    Complementarity is not something that can be purchased and installed on a system, but it is a feature that can result in better performance and lower installed power. Systems possibly based on (full or partial) complementary resources may have fewer failures in service and less sensitivity to drought periods.
    Jethro Betcke · Carl von Ossietzky Universität Oldenburg

    At a conference I once heard the joke: autonomous PV systems have the highest number of PhDs per Watt.  Because autonomous PV systems are mostly also hybrid systems in one way or another, there is plenty of literature about the subject you are interested in.

    Some keyword suggestions for your search:

    -autonomous PV systems
    -rural elctrification
    -micro-grids
    -PV wind diesel hydro hybrid systems

    Once you have the literature you can contact the authors with more specific questions.

  • Vincent Dani added an answer in DIG Labelling:
    Probe optimization in DIG-labelled In situ hybridization?

    Hello all, 

    I'm trying to make some DIG-labelled probes work, and i'm not sure where to start trying to optimize the protocol. I'm doing ISHES on e12,5 mouse embryos, fixed ON in PFA 4%. My issue is that I get decent staining in the midbrain but I don't seem to get good staining in the forebrain, as it seems the gene is less expressed there. (Actually, I have issues with most probes in that area).  

    I've tried longer washes after the hybridization step just because I thought that would reduce the background and I would be able to stain longer, but it washed my probe as well.

    If anyone has experience optimizing a protocol to make probes work, where do you start? Hybridization temperature? lenght of Washes? Is there anything else that can be played with?  

    If you need the complete protocol, let me know and I'll add that info. 

    Thank you very much all in advance!!!

    Vincent Dani · University of Nice-Sophia Antipolis

    Hi,

    You can play with all of the different step ...

    The complet protocol may be usefull

  • What are the physiological mechanisms involved in cognitive impairment?

    What are the physiological mechanisms involved in cognitive impairment?

    Damian G Kelty-Stephen · Grinnell College

    The answer may depend, unfortunately for compact answers in science or here in RG, on what sort of impairment you are interested in.  Impairment following insult to neural tissue?  Or impairment over the longer-haul of development over the lifespan? The answer can be more surprising as you move from the double-dissociation options for the former to the more complex phenomena of the latter.

    It is often quite straightforward to implicate physiological mechanisms within the closely related neural circuitry, as Abhijit's helpful answer points out. However, there a lot of newer findings showing the effects of things we think of as farther "downstream" and more as "outputs." Curiously, simple experiential habits like physical exercise, diet can be among the best predictors of impairment over the lifespan. I share the following three that I've been looking at recently:

    http://www.ncbi.nlm.nih.gov/pubmed/25177186

    http://psycnet.apa.org/journals/hea/22/6/559/

    http://library.mpib-berlin.mpg.de/ft/ul/UL_Limits_2001.pdf

    The cropping-up of nonobvious causes now with more data, more diverse scientists, and more ways to measure cognitive performance seems symptomatic (to me and my friends, biased though we all may be) of cognitive phenomena requiring systems-y explanations like those increasingly pursued in biological sciences.

    Best wishes,

    Damian

  • Pathik Kumbhakar added an answer in Single Crystal:
    What is the relationship in single crystal transperency and bearing NLO properties or response?

    NLO response of crystal is based on their molecular hiperpolarizabilities. how to it connect with transperency?

    Pathik Kumbhakar · National Institute of Technology, Durgapur

    If the linear absorption of a material is more it will generate heat radiation and on incidence of high intensity laser radiation damage will occur in the material. Therefore, in any nonlinear optical experiments it is desirable to chose a NLO crystal which have low linear absorption i.e. the crystal should be transparent in the wavelength range of interests.  

  • Could anybody provide me with the written SOP for Waters Micromass Q-Tof Premier Mass Spectrometer?

    Recently, I started working on Q-TOF. I faced a problem in sequential steps to run samples and wonder if the run of GluFib is OK or not. Therefore, I'm looking for a written SOP for Waters Micromass Q-Tof Premier Mass Spectrometer? What's the acceptable chromatogram from GluFib to continue running the samples?

    Fabrizio Donnarumma · Louisiana State University

    You might want to look up what an SoP is. 

    You may find SoP for a particular analysis or a sample prep protocol, but what you need here is a manual with standard procedure. Which should have been provided by Waters.

    I would guess you are infusing GFB and asking yourself if the intensity and mass precision are right.

    These info are in the specs of the instrument. Or in the last spec release which should normally be left to the customer after a PM.

  • Are there similarities between language acquisition and knowledge acquisition? It seems both are interrelated.

    Language is acquired by a child through exposure to the community.Specially from family members. Language is embedded with concepts and ideas. Knowledge is also absorbed with concepts and ideas. Knowledge is gained gradually by interpreting  concepts and ideas. can anybody gain knowledge without a language?

    Fernando Zeballos · Universidad Católica del Uruguay Dámaso Antonio Larrañaga

    Polanyi said: we can know more tan we call tell [1962]. Nonaka [1995] revisited this concept: the "tacit knowledge". Nowadays, the firm's [and nations] competitive advantage flows from its tacit knowledge. 

  • What is the best way to modified activated carbon

    hello

    what is the best way to modified activated carbon. I want to have high surface area and to support metal ? 

  • Gloriam Guenzburger added an answer in Learning:
    Should a teacher focus on 'rigorous learning' or 'learning with entertainment'?
    It has been seen that many teachers in universities have become entertainers rather than focusing mainly on value-addition and learning. A lot of time gets devoted to pleasing the students; knowing them personally; building good relations with them; and telling jokes and creating humour; the focus becomes more of good feedback than rigor. Keeping the audience motivated is good for effective teaching; but since a lot of time goes in entertainment less time remains for analysis and conceptualization. What is your preference and why?
    Gloriam Guenzburger · State of California

    @Luciano Mariani: the poetic version of Yerkes-Dodson Law. Amen.

    Truly gifted learning facilitators are capable of keeping their students on just that fine line.

  • Nathaly Chavarria added an answer in Dental Caries:
    Which is the most important risk factor for dental caries?

    including social and biomedical factors 

    Nathaly Chavarria · Universidad Cooperativa de Colombia

    La Caries dental es una enfermedad compleja presenta factores de riesgo determinantes sociales y biológicos asumo que el factor necesario y suficiente para que se presente es la placa bacteriana sin disturbio es decir placa madura.