Acid pasting

AMPS-sulfuric acid paste, electrochemical etching 11.6 7.1... 

Fumed silica/sulfuric acid paste, electrochemical etch 21.7 10.7... 

Salicylism, or salicylic acid toxicity, is characterized by rapid breathing, tinnitus, hearing loss, dizziness, abdominal cramps, and central nervous system reactions. It has been reported with 20% salicylic acid applied to 50% of the body surface, and it has also been reported with use of 40 and 50% salicylic acid paste preparations [7]. The author has peeled more than 1,000 patients with the current 20 and 30% marketed ethanol formulations and has observed no cases of salicylism. 

Knox, J.A. "Acidizing Past, Present, and Future," 1973 Annual Technical Meeting of the Petroleum Society of CIM, Edmonton, May 8 12. 

Anhydrous tin(IV) oxide ( Superlite grade) and 6-stannic acid ( Metastannic acid ) were supplied by Keeling Walker Ltd., Stoke-on-Trent. 6-stannic acid paste was prepared at Chinghall Ltd., Milton Keynes, by dispersing Keeling Walker s Metastannic acid, at a level of 73% in a phthalate plasticiser. Colloidal tin oxide, a 25% aqueous dispersion of Sn02> was supplied by Nyacol Products Inc., Ashland, Mass., U.S.A. 

Less widely used methods include acid pasting, i.e., dissolving the material in a medium such as chlorosulfonic acid and precipitating it in water, or milling the crude pigment. These methods gain importance whenever phthalocyanine is to be chlorinated by a route other than with aluminum chloride or acids. 

Another method, used particularly with phthalocyanine blues and greens, involves dissolving the pigment in a strong sulfuric acid (acid-pasting) and then controlling the particle size during precipitation into water. 

A peptide is incubated with the carboxypeptidase enzyme, and the appearance of free amino acids is monitored. In theory, the amino acid whose concentration increases first should be the C terminus, and the next amino acid to appear should be the second residue from the end. In practice, different amino acids are cleaved at different rates, making it difficult to determine amino acids past the C terminus and occasionally the second residue in the chain. 

Acid Pasting. The crude pigment is dissolved in a massive excess of concentrated sulfuric acid, from which it is then reprecipitated in a controlled manner by drowning out the acid solution into iced water to obtain the red-shade, crystallizing-grade, alpha copper phthalocyanine blue. 

Acid Swelling. The crude is treated with a smaller volume of less concentrated sulfuric acid than is used in the acid pasting procedure after which the acid-swelled paste is pumped under controlled conditions into iced water to obtain copper phthalocyanine blue as the alpha crystal. 

Metal-free phthalocyanine has been prepared in several forms a (tetragonal), P (monoclinic), x (hexagonal), and x. Figure 7 shows the interconversions. For example, treatment of Monolite Fast Blue GS (ICI) with hot dimethylformamide followed by ball milling in isopropyl alcohol yields the fi-form as needles, whereas acid pasting produces the a-form as needles and flakes (Loutfy, 1981). Milling under different conditions yields either the x-form as needles or flakes (Takano et al., 1984 Kakuta et al., 1985) or the x-form as needles (Sharp and Lardon, 1968 Hackett, 1971). The x-form as rods has been... 

Metal-free phthalocyanine (H2PC) exists in the a, P, r, and X polymorphic forms. The a,P, and X forms have been characterized by electrochemistry [36a], fluorescence spectroscopy [36b], and optical absorption [36c] and a,p, and t forms by C-NMR spectroscopy [36d], optical absorption, and X-ray powder diffraction [36e]. Figure 19 shows the optical absorption spectra of the four forms. The t form has been further characterized as to particle shape (Types I and II) [36f]. The as-synthesized y9-H2Pc is converted to a-H2Pc by acid pasting and this can be converted to the X or T forms with mechanical milling under specific conditions. The X and r forms convert to the P with thermal, solvent, or extended mechanical treatment. 

A patient suffering from chronic gout has renal calculi and is a high exeretor of uric acid. Past drug history includes severe hypersensitivity to antibacterial sulfonamides. The most appropriate drug for treatment of this patient is... 

Many other workers have studied the effects of adding phosphoric acid to the electrolyte. The results vary dramatically with the acid concentration, paste composition, acid paste ratio, and application. Voss recommends that cells should be operated above 15°C to decrease mossing, and summarizes the effects of phosphoric acid in lead-acid cells as follows ... 

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