borodin

There's an excel sheet with a plot, if you would like to check! Thanks again:) PS - sorry my bad english.. Exemplo.xlsx.zip

Hi! How are you? I'm doing a project on chemistry and i need some help on analysis of data, if possible. I think i can get more help from a mathematician then a chemist. I'm studying a property (CMC, critical micellar concentration) of a solution, and to treat data i trace a plot of concentration (m) Vs specific conductivity (k), like this. Then with a linear fit i get two straight lines, and the intersection is the CMC: The problem begins when the variation isn't relevant, like this: Now, i've found this paper where get a complicated data treatment and get a derivate-like result: Paper: http://www.scienceforums.net/forum/attachment.php?attachmentid=2562&stc=1&d=1277950968 On page 138, in Results and Discussion, they said: The problem of estimating the derivatives of the regression curve has beenvresolved by implementing the local polynomial regression estimator in the programming language Matlab, using the quartic kernel and plug-in optimal AMSE bandwidth. The calculation of hopt(x0) was achieved by estimating σε2 using a local polynomial regression, with a pilot bandwidth; the Parzen-Rosenblatt kernel estimator for f(x0) was also obtained by using a pilot bandwidth, and a parametric regression and a local polynomial regression were used for m(p+1)(x0). To avoid the problem of choosing an initial value h0, an iterative ap- proach was taken starting with a large h0. This initial pilot bandwidth produces another bandwidth, and this last one produces another, and so on. The iteration is continued to convergence. This is chinese for me. I've never work in mathlab,so..it's sound very difficult to me to replicate this method, i just know the basics of math to work. But i would like give it a try. I've done the first and the second dervivative (dk/dm) ant it didn't worked. Its difficult to work with mathlab and this plugins? Is doable to a non-expert? Do you have any sugestion of a method to do the analysis of my data? Thank you! I A nonparametric approach to calculate critical micelle concentrations- the local polynomial regr.pdf

Hello! I am doing a study on cytochrome c oxidase and am having some problems at the redox part. If the half reaction Cu2+ + e- -> Cu+ Cu2+/Cu+ = 0,153 V so, the inverse is: Cu+/Cu2+ = -0,153V Right? Thus, how the pair Cu2 + / Cu + catalyzes the oxidation of Fe2+ to Fe3+ (Eo = 0.77V). Another question: higher the spin of a complex, higher the redox potential? Right? I would be gratefull by help. thanks!!

Yes.. Thanks!

Hi. I'm on a little project trying to study encapsulation of 2-hydroxybenzoic and 4-hydroxybenzoic acid in alpha and beta-cyclodextrin (CD). The method is to keep constant the concentration of the acid and variate the CD concentration, adding NaCl to keep the ionic strength constant. Right now i'm only doing UV-Vis measurements and i'm having bad results (or bad data treatment). I've attachted some results. Any sugestions? I'm only using the Benesi-Hildbrand Model, the only i found to study encapsulations. I'm feeling a little lost and my teacher don't have much time to dedicate to this project.. Thanks!!! PS - Sorry my bad english.. :S 2HB - aCD.xls.zip

UC, I'm just checking others opinions (not devaluating SM's user opinions, obviously)! Thanks! Actually i think i find a portuguese VWR! Lets see what they say..

Hi I'm searching for a nice supplier of lab material to begin trying do some experiments at home. I've found this one: http://www.starscientificindia.com I've heard that asian glassware aren't standardized, but they have the ISO. They have nice prices. What do you think? Thanks!

Hi! I've found valuable information. If someone needs please PM me! Now we are trying to prepare cyclodextrine Hexa-Hydrate. I've found one metod that is just put the cycldextrine in the desiccator with some Calcium Nitrate. Have you heard about that? How this work? There are some paper where this information is available? Why only 6 molecules of water will connect to Cyclodextrin? Thanks!!

Hi! I'm in a project where we are trying to study some properties of encapsulation of some phenolic ácids and flavones by cyclodextrins. I've found this paper: Cyclodextrins and Molecular Encapsulation. Author: Szejtli, J. Source: Encyclopedia of Nanoscience and Nanotechnology, Volume 2 , pp. 283-304(22) , but i can't access it. Could you give me a light where i can search for UV-Visible, IR, pH, Solubility data? I don´t know yet the route for the study.. :| Thank you very much! PS - Sorry my bad english! :|

Hi, I have poor knowledge in electronics but i'm trying to do a wind generator with an old vcr motor. My first problem is in finding the 3 phases ( it is a 3 phase motor, isn´t it?) in this confusion of connections.. Could you help me or tell me where i can get this information? Thanks!!

Hi. I've to do the characterization (UV/Vis; FTIR; magnetic susceptibility; condutimetry;) of some Nickel(II) complexes like Ni(Et2en)2X2 where X= Cl-, NCS-, NO3- and I-. It's a college mini-project: i've to write a cientific paper following the rules of some chemistry journal. Can you help me finding some information about that? Like books to search..or free net papers.. How can i show the results of a UV/Vis and FTIR analysis on a paper? Because de Bologna declaration i'm having lab classes and haven't yet attend theoretical ones . Thanks for the atention. Best regards!

Thank you all! The apresentation of the report was last friday, the day of you firts reply. The mechanism of the reaction that i've found and used was: C4H8O (aq) + NaOCl (aq) -> CH3(CO)CH3 (aq) + NaCl (aq) + H2O (l) Represented by the intermediate reactions: NaClO (l) ↔ Na+ (aq) + ClO- (aq) ClO- (aq) + CH3COOH (l) → HClO (aq) + H3COO (aq) C4H8O (aq) + HClO (aq) → CH3(CO)CH3 (aq) + HCl (aq) + H2O (l) Elimination of sodium hypochlorite: Na2S2O3 (aq) + H2O (aq) ↔ 2NaHSO3(aq) HSO3- (aq) + H2O (l) → SO42- (aq) + 3H+(aq) + 2e- 2HClO (aq) + 2H+ + 2e- → Cl2 (aq) + 2H2O (l) Testo, thanks! I've a doubt: The last destilation is to remove the water, right? why the acetone was dried with sodium carbonate and then destilated (simple), and not the inverse process? Sodium carbonate don't remove only small portions of water? Thanks anyway! Best regards!

Watch this:

Hi again! I've found the reactions, but now i've another problem. I can't find the products (destiled and non destiled) of the two destilations (simple and fractionated). Can you help? Sorry be boring!

Nice topic! About Flashbacks: Dear Dr. Shulgin: I have heard that LSD never leaves your body, and can stay in your brain for many years? Is this true, and is this what causes the so called “flashbacks?” Thanks! -- B & Rhys Dear B & Rhys: The myth of the “lingering molecule” of LSD was given support by the Drug Enforcement Administration at a two day meeting in San Francisco, in late 1991. The DEA invited some 200 participants from law enforcement groups (both domestic and foreign) to share information concerning LSD. The law enforcement agents were told that not only was the storage location known (the frontal lobes of the brain) but also the length of time it stayed there (up to twenty years). “The evidence is all about us,” they were told. “The indiscriminate use of LSD in the Summer of Love (in the 1960s) has led directly, through the re-release of these hidden-away molecules and the resulting flashbacks, to the hordes of the homeless, the psychotic, and the disenfranchised here on the streets of San Francisco.” The flashback phenomenon with LSD is rare but real. An auditory or visual clue can bring back a passing memory of an earlier experience. The residue of any tangible quantity of the chemical itself, in the brain or blood of the user after 24 hours, is, however, total nonsense. -- Dr. Shulgin http://www.cognitiveliberty.org/shulgin/adsarchive/lsdflashbacks.html A flashback is a normal phenomenon in human mind. How many times just a smell or a sound is needed to bring back a forgotten child experience/situation ? But LSD in the brain after 40 years? That isn't science!! Like a free radical?? ) Now, Any way to induce hallucination without drugs? The floatation/isolation tank is very effective! Read the experiences of Dr. Lilly in the 50's. http://www.samadhitank.com/

HI! Could you help me to find information about acetone preparation from 2-propanol ? I have to do this preparation at college and the only information i’ve found isn't enough. The procedure indicates that the 2-propanol is oxidated by hypochlorous acid (HClO). The source of HClO is the reaction of sodium hypochlorite with acétic acid. I need to explain all the reactions, the whats and the whys, and i can't find it anywhere. I've digitalized the procedure if you want to check. http://rapidshare.com/files/77089369/acetone_preparation_from_2-propanol_.pdf.html Thank you! Best regards!