Showing papers on "Phosphotungstic acid published in 1982"

Four methods for determining uric acid compared with a candidate reference method

Abstract: Uric acid as measured in serum by three different uricase (EC 1.7.3.3) methods (aca, Ektachem, and SMAC) and by the SMAC method with phosphotungstic acid was compared with a candidate Reference Method for uric acid. Serum specimens from 83 patients (uric acid concentrations, 19 to 141 mg/L) were analyzed by all five methods. Results were compared by using linear regression analysis, and the mean difference between results by the candidate Reference Method and the four other methods was calculated. Compared with the candidate Reference Method, the aca method gave the smallest deviation from zero for the intercept and the smallest mean difference, and the SMAC phosphotungstic acid method showed a slope closest to unity. The SMAC uricase method had the largest intercept and greatest deviation of the slope from unity.

Preparation of methyl mercaptan

Abstract: PURPOSE: To prepare the titled compound useful as a synthetic raw material of methionine, in high yield and selectivity, by reacting methanol with H 2 S essentially in the first reactor and reacting the by-products with H 2 S essentially in the second reactor, wherein each reaction is carried out in the presence of a catalyst suitable for the respective reaction system. CONSTITUTION: Methyl mercaptan is prepared by the vapor-phase reaction of methanol and hydrogen sulfide. In the above process, the reaction is carried out at 300W430°C in the first reactor containing an active alumina catalyst (e.g. a mixture of active alumina and potassium tungstate) which catalyzes essentially the reaction of methanol with hydrogen sulfide, and methyl mercaptan is separated from the reaction product. The unreacted methanol and H 2 S are mixed with fresh methanol and unreacted H 2 S, and reacted at 300W400°C in the second reactor containing an active alumina catalyst (e.g. a mixture of active alumina and phosphotungstic acid) which catalyzes essentially the reaction of H 2 S with dimethyl sulfide, and methyl mercaptan is separated as a reaction product. COPYRIGHT: (C)1983,JPO&Japio

Cytochemical localization of biliproteins with silicotungstic acid

Abstract: SUMMARY 5% silicotungstic acid (STA) in 6·25% aqueous sodium sulphate has been used as an en bloc cytochemical stain for the localization of biliproteins in the Cryptophyceae. STA also stains a wide range of other proteinaceous structures including the ejectosomes, periplast, pyrenoid, nucleus, cisternae of Golgi and the mitochondrial matrix. The STA technique provides far greater contrast than that of the original phosphotungstic acid (PTA) stain developed by Silverman & Glick (1969a).

Method of synthesizing trioxane in vapor phase

Abstract: PURPOSE: To obtain the titled compound capable of giving high-molecular weight polyoxymethylene in high purity with little formation of by-products without depositing paraformaldehyde nor corroding apparatuses, by bringing formaldehyde in the vapor phase into contact with a heteropolyacid supported on a carrier. CONSTITUTION: A carrier, e.g. silica gel, is gently agitated in an aqueous solution of a heteropolyacid, e.g. phosphotungstic acid, at 80°C, and the carrier is then separated and dried at 120°C under reduced pressure to afford a catalyst containing the heteropolyacid supported on the carrier. The resultant catalyst is then packed in a stainless steel tube, etc. having a jacket, the stainless steel tube, etc. and brought into contact with the catalyst consisting of the heteropolyacid supported on the carrier and give the aimed trioxane of high purity. COPYRIGHT: (C)1984,JPO&Japio

Characterization of the Nuclear Lamina in an Insect by Differential Staining

Abstract: Abstract The nuclear envelope of the larval fat body in the blow fly Calliphora vicina reveals a conspicuous nuclear lamina. It appears homogeneous, Fibrous or granular depending upon the fixing and staining methods. The best relative contrast for the nuclear lamina and the nuclear pore complex is obtained with a phosphotungstic acid staining procedure designed for proteins.

Electron density distribution of dry avian tendon.

Abstract: The electron density profile along the unit cell of dry native collagen is determined. The method used is a modification of one that has been used successfully for wet native collagen. Uranyl acetate and phosphotungstic acid were used for isomorphous addition in phase determination and were located by electron microscopy. Structure factor magnitudes for dry collagen with and without the heavy metals were obtained from X-ray diffraction data. The first 9 orders were investigated. Standard Argand diagrams provided a unique solution for the phase of each. The resultant profile suggests that significant conformation changes occur in both the non-helical ends and the triple-helix portions of the molecules.