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Perchloric acid
About: Perchloric acid is a research topic. Over the lifetime, 5295 publications have been published within this topic receiving 81476 citations.
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TL;DR: Interfacial polymerization is shown to be readily scalable to produce bulk quantities of nanofibers and the measured Brunauer-Emmett-Teller surface area of the nan ofibers increases as the average diameter decreases.
Abstract: Uniform polyaniline nanofibers readily form using interfacial polymerization without the need for templates or functional dopants. The average diameter of the nanofibers can be tuned from 30 nm using hydrochloric acid to 120 nm using perchloric acid as observed via both scanning and transmission electron microscopy. When camphorsulfonic acid is employed, 50 nm average diameter fibers form. The measured Brunauer-Emmett-Teller surface area of the nanofibers increases as the average diameter decreases. Further characterization including molecular weight, optical spectroscopy, and electrical conductivity are presented. Interfacial polymerization is shown to be readily scalable to produce bulk quantities of nanofibers.
1,291 citations
TL;DR: This chapter is based on the assays of intermediates of the citric acid cycle and related compounds by fluorometric enzyme methods based on instruments capable of giving a full-scale deflection of the recorder with 0.25μM NADH, with a noise level less than 2%.
Abstract: Publisher Summary This chapter is based on the assays of intermediates of the citric acid cycle and related compounds by fluorometric enzyme methods. An eppendorf fluorometer or a metabolite fluorometer are instruments capable of giving a full-scale deflection of the recorder with 0.25μM NADH, with a noise level less than 2%. At such high sensitivities, the full progress of each enzymatic reaction is recorded. The following accounts for the majority of difficulties and inaccuracies commonly encountered with fluorometrie enzyme methods: All solutions should be dust and particle free; the cuvettes should be temperature equilibrated; Particular care should be taken to avoid contamination of solutions with enzymes, or cross-contamination; Fresh enzyme solution must be made each day; Solutions of pyridine nucleotides are best prepared each day and stored on ice. NAD+ and NADP+ are most stable in a slightly acid solution, and may be diluted with distilled water; and all standard solutions should be neutralized, and assayed spectrophotometrically on the day of use. Metabolic intermediates other than reduced pyridine nueleotides, total CoA, fatty acyl-CoA, and fatty acylearnitine compounds are measured in neutralized perchloric acid extracts of tissues. Perchloric acid is generally more convenient to use than trichloroacetic acid for the extraction, because it may be removed by precipitation as the potassium salt.
880 citations
TL;DR: In this paper, the structure and orientation of water molecules at a highly ordered Au(111) electrode surface in perchloric acid have been investigated in-situ as a function of applied potential by means of surface-enhanced infrared absorption spectroscopy.
Abstract: The structure and orientation of water molecules at a highly ordered Au(111) electrode surface in perchloric acid have been investigated in-situ as a function of applied potential by means of surface-enhanced infrared absorption spectroscopy. This newly developed infrared spectroscopy technique enables the observation of the electrode/electrolyte interface at a very high sensitivity without interference from the bulk solution. The spectrum of the interfacial water significantly differs from that of bulk water and drastically changes in peak frequencies and band widths around the potential of zero charge (pzc) of the electrode and at about 0.3 V positive from the pzc. The interfacial water molecules are weakly hydrogen-bonded at potentials below the pzc and form a strongly hydrogen-bonded ice-like structure at potentials slightly above the pzc. The ice-like structure is broken at more positive potentials due to the specific adsorption of perchlorate ion, where one OH moiety of water is non-hydrogen-bonded ...
601 citations
TL;DR: Various strong acids and their neutral salts refolded the acid-unfolded cytochrome c and apomyoglobin to the A states as was the case with HCl, confirming that the anions are responsible for bringing about the transition.
Abstract: We have previously shown [Goto, Y., Calciano, L. J., & Fink, A. L. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 573-577] that beta-lactamase, cytochrome c, and apomyoglobin are maximally unfolded at pH 2 under conditions of low ionic strength, but a further decrease in pH, by increasing the concentration of HCl, refolds the proteins to the A state with properties similar to those of a molten globule state. To understand the mechanism of acid-induced refolding of protein structure, we studied the effects of various strong acids and their neutral salts on the acid-unfolded states of ferricytochrome c and apomyoglobin. The conformational transition of cytochrome c was monitored at 20 degrees C by using changes in the far-UV CD and in the Soret absorption at 394 nm, and that of apomyoglobin was monitored by changes in the far-UV CD. Various strong acids (i.e., sulfuric acid, perchloric acid, nitric acid, trichloroacetic acid, and trifluoroacetic acid) refolded the acid-unfolded cytochrome c and apomyoglobin to the A states as was the case with HCl. For both proteins neutral salts of these acids caused similar conformational transitions, confirming that the anions are responsible for bringing about the transition. The order of effectiveness of anions was shown to be ferricyanide greater than ferrocyanide greater than sulfate greater than thiocyanate greater than perchlorate greater than iodide greater than nitrate greater than trifluoroacetate greater than bromide greater than chloride.(ABSTRACT TRUNCATED AT 250 WORDS)
547 citations
TL;DR: The ability of bentonite clay to remove Pb(II) from aqueous solutions and from nitric acid, hydrochloric acid and perchloric Acid solutions has been studied at different optimized conditions of concentrations, amount of adsorbent, temperature, concentration of electrolyte and pH.
519 citations