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  • S. Abd El.Aleem added an answer in Cement
    How can I find the percentage of cement in harden concrete?
    Is there a test procedure to find out how much cement there is in harden concrete?
    S. El.Aleem · Fayoum University
    I completely agree with Dear Prof. and Dear colleague that, You can take a core sample of known weight and volume, and dissolve it V in a strong acid to see what remains after washing and drying the remaining aggregates. Then re-weigh the remaining aggregates, and place them in a flask of water, and see the increased displacement of the water in the flask after getting rid of the air bubbles. The initial condition has a combined specific gravity of concrete, the final condition has the specific gravity of the aggregates, and the Portland Cement has a specific gravity of about 3.15 if I remember correctly. Weight of the core minus the weight of the aggregates = weight of the cement and water mixture. Volume of the core minus the volume of the aggregates = volume of the cement and water mixture. Specific gravity is a comparison of the weight of an object in air compared to the weight of an object suspended in water where the water has a volume, mass and weight of 1.00 in the metric system. You must also remember that the concrete is made with a mixture of cement and water, so as the water increases, the volume of the cement and water mixture increases, and its specific gravity of the mixture decreases. Good concrete has a higher cement portion, and a lower water portion with a water to cement ratio of less than or equal to 0.40. Good concrete has a W/C between 0.3 and 0.4. That is the total weight of water divided by the total weight of cementitious materials should be between 0.3 and 0.4. The strength of concrete falls off as the W/C increases. The History of concrete made simple mixtures of 1 cubic foot boxes of materials where the Portland cement weighed 94 lbs for one cubic foot. A typical mixture is 1:2:3 where 1 box of cement is added to 2 boxes of sand, and 3 boxes of rocks and just enough water is added to barely make the mix mixable and to completely cover all of the aggregates with a Portland cement and water slurry.
  • Bassam Hamdar asked a question in Music Education
    Is classical music still relevant today?
    Classical music is art music which is based on the traditions of western music .The term classical music entails a wide period that extends from the 11th century up to the present day. Classical music is a serious music that differs greatly from the principles of today’s music, namely it differs from folk, jazz, or other today’s popular tradition. Classical music encompasses the works of Bach, Mozart, Beethoven, Chopin, and others. However, in today’s world rap music, rock, country, and alternative music dominate today’s tastes and today’s generation. Unlike today’s music, classical music is not usually heard everywhere or on the radio in public places. Therefore, is classical music still relevant today? Has classical music become a thing from the past and for the past? Is not classical music the music of value and real art? What is your input on classical music?
  • What are the optimization problems that exists in radio mobile network (GSM …) and have been solved using metaheuristics ?
    Hello i'm PhD student in computer science . The object of my thesis is "solving optimization problems in cellular network". It consist in resolving optimization problems that exist in radio mobile network using metheuristics. I need to determine this optimization problems. Like the frequency assignement problem
    Dahi Abd Zakaria Abd El Moiz · Université Constantine 2
    #Mahboobeh Parsapoor , i dont see any link to th document that you mention ....
  • It is true that most owners of PhD degrees in economics - are the graduates of university physics departments?
    I do not know. If that is so, then why ?
  • What instrument can i used for effective analysis of the real electronic circuit to identify fault components?
    Am looking for a device or system that can help me on analyzing the real electronic circuit to identify fault components.
  • Michael Tem added an answer in GSAS
    How can I write constraints while refining occupancies in different types of compounds in GSAS software?
    I am using GSAS suit with EXPGUI software for Rietveld refinement.
    Michael Tem · University of Indonesia
    first of all u need to add the atom that share the same position and the total accupancy must be 1. Go to constraints tab - click add new constrain - select both atoms by ctrl click - click blank button right to the Variable and select what kind of constraint.
  • Electrophoretic separation of proteins of very high molecular weight
    I am interested in separating high molecular weight proteins ( MW 300,000-1,000,000 by electrophoresis . Anyone know of a reliable technique for this?
  • Why does music evoke emotions or feelings?
    Music has many bodily effects. This is not trivial.
    Sylvain Clément · Université Charles-de-Gaulle Lille 3
    Another inspiring reading is the following paper : Brandt, A., Gebrian, M., & Slevc, L. R. (2012). Music and early language acquisition. Front Psychol, 3, 327. doi:10.3389/fpsyg.2012.00327 it is available here : http://journal.frontiersin.org/Journal/10.3389/fpsyg.2012.00327/full Although it is more about the links between the development of language and musical abilities it gives really interesting references about works in ethnomusicology, musical neuroscience... Worth reading for anybody interested in music cognition/neurosciences
  • Which is better to join higher education programs based on research or courses?
    I would like to hear from you based on your experience, observations in actual situations. I am grateful to any participation.
  • Do you believe in first impression?
    Did you once have the chance to exam your first impression with the future followings?
    Nelson Elias · Rio de Janeiro State University
    Dear Jeanan Yes Initial judgments about a person are hardly broken. Even if other information contradict the view formed at first, she continues imposing long . In a space shorter than a wink time, the human brain constructs images difficult to be removed later. The power of ideas shaped by the time it hits the eye of a person is so strong that even the facts are able to disprove them easily.
  • What are the acceptable range of the skewness and kurtosis for the normal distribution of the data?
    It is desirable that for the normal distribution of the data the values of skewness should be near to 0. What if the values are plus/minus 3 or above?
    Edgar Mesquita · University of Minho
    A rule of thumb is -1 to 1 amplitude. Nevertheless, as said by Casper you should calculate CI 95% for adequate results reporting.
  • Behrouz Ahmadi-Nedushan added an answer in Energy
    What do you think are the most important personal characteristics of a successful researcher?
    Is there in your opinion some personal characteristics that are recurrent in successful researchers? What is opinion about the following personality traits? 1. Intellectual curiosity, 2. determination, 3. self-motivation, 4. competitiveness, 5. team-work capabilities, 6. humbleness, etc. Are there other relevant issues that I have not mentioned? Do you feel there is a logical importance ranking among the above mentioned characteristics? Do you think the ranking depends on the specific research field or on other issues?
    Behrouz Ahmadi-Nedushan · University of Yazd
    Carlo answer was comprehensive , and I agree with his assessment. I can think of other characteristics such as honesty and motivation.
  • Is there a difference between authority and responsibility?
    Are they two sides of the same coin? President Truman had a sign on his desk saying "The buck stops here," meaning he was willing to take the ultimate responsibility for the decisions of his administration.
  • Is the ecosystem adopt for any possible desalination of salt water lagoons?
    In northern Sri Lanka , the Jaffna peninsula is having it's 26% of the land by salt water lagoon. Now proposals are pipelining to convert these lagoons in to sweet water lagoons. But fishing community and environmentalist are opposing this project. I want a good conducive discussion in RG The attached article deals with an on going research
  • Can a metal oxide having lower surface area exhibit better bactericidal property than a metal oxide having higher surface area?
    Can a metal oxide nanoparticle having lower surface area exhibit better bactericidal property than a metal oxide (same material) nanoparticle having higher surface area? If so, then what could be the factors which are responsible for this behaviour?
    Prashanth Gopala Krishna · Sir M. Visvesvaraya Insititute of Technology
    Thank Mr. Muhammad. Could you kindly give few references regarding this ?
  • Cezary Polakowski added an answer in Chitosan
    What are the optical properties of chitosan?
    I need to measure the particle size distribution of chitosan spray dried particles in the sub-micron range. I am using the laser diffraction technique. I need the real refractive index of chitosan and the imaginary refractive index (absorption) as well.
    Cezary Polakowski · Polish Academy of Sciences
    Another one :)
  • Uyen Le Thanh Nha asked a question in Cancer Biology
    Could anyone suggest me some reasons of my troulbe in shRNA transfection?
    I'm trying to transfect shRNA-lentiviral particles to knockdown my target gene expression in leukemia cell line. I made 5 different shRNA (1-5) fragment to address my target gene. After puromycin selection step, I expanded the infected cells by cell culture in 2 days but I observed that dead cell appeared and gradually increased in shRNA-1 without RNA expression-level change while others shRNA-infected cells were still alive and proliferating. I did checked the puromycin and polybrene toxicity concentration before transfection, and all the samples were carried out at the same condition. I also run "nucleotide blast" to check the specificity of shRNA sequences. I don't know how to explain this phenomenon. Is there anyone used to experience this problem?
  • Is there any non-destructible method to estimate the compressive strength of concrete?
    Compressive strength of concrete is estimated by using UTM/CTM machine by breaking the specimen. Is there any technique by which the specimen remains intact and we can get the compressive strength?
    S. El.Aleem · Fayoum University
    Dear Prof. and Dear colleague Ma Chau Khun, thank you. Good and interesting comment.There are several indirect tests that we can use to estimate the compressive strength of concrete. We can use Rebound hammer or PUNDIT velocity tests.
  • How can I get consistent results in a MTT assay?
    I performed an MTT assay for the synthetic dye on L929 and MDA breast cancer cell line. Initially incubation was the cells in 96 well plates for 24 hrs followed by dye treatment for 24 hrs after washing the wells with sterile PBS. After 24 hr treatment the media was removed and then MTT was added and incubated for 4 hrs. But results are not up to the mark.
    Chithra Ramanathan Pullai · Putra University, Malaysia
    Thank you.
  • Yordan Epitropov added an answer in Geometry
    Are there mathematicians, scientists or philosophers whose work you view as influencing historical events in a minor or in a major significant way?
    Do you think that the interaction between such scholars has led to the success of their work in making an impact? Scholars such as Euclid (geometry), Newton (science), Plato (philosophy) have been very influential in shaping the way we see the world. For example, Euclid’s Elements written in Alexandria around 300 B.C. became a standard work in geometry. It is one of the most widely read, translated and commented on work in European history. It was translated into Arabic around 800 A.D., into Chinese in 17th century and into Sanskit in the 18th century. The first english version of Euclid’s Elements was Sir Henry Billingsley’s translation published in 1570. Euclidean geometry has been enormously influential in shaping our view of the world. For more about this, see http://www.hf.uio.no/ikos/english/research/projects/euclid/ Plato, 428-348 B.C., descendent from kings of Athens and Messenia, student of Socrates, teacher of Aristotle, founded the Academy of Athens, one of the institutions of higher learning in the Western world. He wrote about justice, beauty, equality, political philosophy, theology, cosmology, epistemology and the philosophy of language. For more about this, see http://www.biography.com/people/plato-9442588#awesm=~oBHUNDFF6ggpWQ A central notion in Plato’s philosophy is the theory of forms. The only true being is founded upon the forms, the eternal, unchangeable, perfect types, of which particular objects of sense are imperfect copies. This theory has been enormously influential in science and mathematics. For more about this, see http://www.ams.org/notices/201002/rtx100200239p.pdf Isaac Newton, 1643-1727, son of a farmer, Professor at Cambridge University, taught optics, introduced a theory of colours of light and theory of gravitation, published his Mathematical Principles of Natural Philosophy, 1687, introducing infinitesimal calculus, co-discovered (with Leibniz). During his study of optics, Newton investigated the refraction of light, demonstrating that the multi-coloured speturm produced by prism (see attached image) could be recomposed into white light by a lens and a second prism. He showed that colour is the result of objects interacting with already-coloured light rather than objects generating the colour themselves. He designed the first reflecting telescope, demonstrating his telescope to the Royal Society in 1671.
    Yordan Epitropov · Plovdiv University "Paisii Hilendarski"
    This list of great men can be continued indefinitely. But what are those ideologues who changed people's thinking? As, for example, in religion were Buddha, Jesus ...
  • I have recently treated an open (Gustilo II) mid shaft clavicle fracture. What would you prefer as a treatment option?
    It was a mid shaft open clavicle fracture associated with scapular neck fracture occurred after attack with an ax or similar tool. The patient also had a serious head injury. At 3 a.m., I intramedullary placed a 20cm long Schantz pin. Fortunately, the main neuro-vascular structures and lung were intact. There are only few articles related to this topic.
    Zeljko Stepanovic · University of Kragujevac
    Dear Nelson, thank You for Your advice. As I already said, this was an emergency situation at 3 a.m. The goal was to swiftly stabilize the fracture after wound debridement and exploration of neuro-vascular structures. It was a Schantz pin 225 mm long and 5 mm in diameter. I agree with You about K wires, therefore I used a 5mm pin. I use plates and bone grafting in non-union cases. In this particular situation plating of the clavicula would be time consuming, in my opinion. Best regards
  • Can we have OPC as a control mix for a mix containing High early strength cement, fly ash and silica fume
    S. El.Aleem · Fayoum University
    My dear friend, In my opinion you must take a high early strength cement as a control (Reference) for a mix containing High early strength cement, fly ash and silica fume. All the best Regards Sincerely Yours Dr. Saleh Abd El Aleem drsalehabd@yahoo.com saa09@fayoum.edu.eg
  • Arun V Panat added an answer in Pollution
    What is your point of view on the effect of pollution on evolution?
    Increasing pollution during last century has caused many changes in biological and genetic characteristics of species on earth. Pollution can be considered as one of the causes of decrease in average life span of human beings and extinction of some of the species on earth. What is your point of view on this?
    Arun Panat · ASC College at Rahuri , affiliated to University of Pune
    I agree with Mahfuz Judeh that increasing pollution has produced many negative changes in biological and genetic characteristics but as yet no one thinks of some positive sides too. Pollution as we call then biological and genetic changes in the species and then evolution of more fit species is the journey. Today we feel that these are negative changes but in future they are essential changes. Emergence of new species after say 1000 or 10,000 or 100000 years is a continuous process. It will go on and on ! In fact today's species is a result of many such interactions which occurred 10000, 100000 or 1000000 years ago !
  • How can I calculate the bounds of a 0-1 programming problem in which the parameters are dependent on simulation results?
    I'm studying a combinatorial optimization problem which is related to machine scheduling in a hydraulic system. We have an objective function and constraints, like a combinatorial optimization problem. However, the parameters of the model are unknow, because we need to simulate the hydraulic system. Therefore, we can use a decision variable vector (the scheduling of a set of machines, in periods of hours) for calculating of hydraulic features of the system. Finally, we can measure the objective function and if the solution is feasible. It is a minimization problem. I'm interested in obtain lower bounds, for a B&B algorithm, or upper bounds, with heuristics.
    Bruno Prata · Universidade Federal do Ceará
    Dear Hermann, Let n the number of pumps and t=24 hours (daily operation), we have 24n binary decision variables. This is our problem: http://www.iwaponline.com/ws/01003/ws010030315.htm
  • How can I measure indoor air pollution in rural areas?
    If we would measure indoor air pollution in a rural household, what is the standard procedure for that and standard limit? In those areas, almost all of the people depend on agriculture and local resources. For cooking purposes they use traditional C type Chullas (biomass cookstove).
  • Didier JAMBOU added an answer in Cell Culture
    How to dissolve Indomethacin for cell culture purpose ?
    I used ethanol (50%) stock solution, it was dissolved properly but after further dilution it showed some haziness.
    Didier JAMBOU · Centre Hospitalier Universitaire de Nice
    Dear Anil, I think indomethacin is difficult to dissolve. Not in water, so in ethanol and possibly in methanol. You have to study the solubility of the product in some books like the Meck index. So good for dissolution in hydrophobic solutions or ethanol (intermediate one). But take care when you further dilute if it is directly in phosphate buffered saline ie, because it precipitated with the phosphates of the solution. So directly to dissolve in RPMI medium without phosphate. And it depends also the final concentration you want. Often in research we begin at high concenrtations to be sure to have an effect, but which are not compatible with blood concentrations you obtain ie when you treat a patient. You have to know which concentration you obtain during treatments, in blood sample of human (see bibliography). I hope usefull. Regards Didier
  • Nelson Elias added an answer in Logic
    Is it guaranteed that an (A) student will be successful his practical life after graduation?
    What is your opinion?
    Nelson Elias · Rio de Janeiro State University
    Dear Jeanan Graduation does not fully meet the requirements for the job market, being necessary in most cases a pos-graduation course that allows more knowledge and a greater chance to achieve professional fulfillment
  • What are your top five values in order of importance; do they facilitate or hinder your research? How?
    Some times one's values are highly helpful in undertaking and conducting research; but sometimes they may hinder it as well. How is it with you?
    Nageswara Posinasetti · University of Northern Iowa
    There is another similar thread https://www.researchgate.net/post/What_do_you_think_are_the_most_important_personal_characteristics_of_a_successful_researcher
  • What is the best way to pre-activate NK cells?
    There are some options in the literature, pre-culture with K562 cells, add IL-2 or IL-15 or antibodies against NKG2D or NKp46... But I don't know which one would be the best and fastest way to do it. Does anybody have experience with this?
    Chithra Ramanathan Pullai · Putra University, Malaysia
    Thank you friends. Super clues to solve my problem in activating NK cells. How about if im activating with OK432 ? Does anyone have tried this protocols ? All the best.
  • Samahe Sadjadi asked a question in Organic
    I want to invite some contributors for my new book. How can i be assured that contributors respect copyright rules?
    Book publishing