Determination of impurities in tungsten metal: Determination of iron

A method is proposed for the determination of iron present as an impurity in tungsten. 4,7-diphenyl-1,10-phenanthroline forms a stable complex with iron (present as the ferrous ion) which can be extracted by chloroform, in presence of alcohol, and determined absorptiometrically. Tungsten is complexed as citrate, and iron is reduced with sodium dithionite.     

Determination of uranium,zirconium, magnesium and iron in bismuth alloys

Uranium in bismuth alloys is determined by a procedure where E.D.T.A. is added to complex bismuth and other metals and uranium oxinate is extracted by chloroform and determined spectrophotometrically. Zirconium is determined spectrophotometrically using alizarin S as reagent under carefully controlled conditions of acidity and time of colour formation. Magnesium is determined indirectly by measuring the absorption of oxine spectrophotometrically after precipitating the magnesium oxinate complex and redissolving. Bismuth is first separated by extraction of its iodide complex with methyl isobutyl ketone, and other interfering metals by extraction of their oxinate complexes at pH 6.5. Iron is determined as its thiocyanate complex after extraction with methyl isobutyl ketone, bismuth thiocyanate remaining in the aqueous phase.     

High-pT pion production in ππ interactions

Charged pion production in high energy π^-π^- interactions is studied in the p_T region of 1–2 GeV/c. The characteristics of pion production in π^-π^- interactions are compared with those in π^-p and pp interactions. The p_T dependence of pion production in these reactions follows a systematic trend which indicates that high-p_T pion production for ππ interactions as well as for πp and pp interactions proceeds via quark-quark scattering as predicted by QCD.     

Inclusive Pomeron-Pomeron interactions at the CERN ISR

Data are presented for the first time on inclusive Pomeron-Pomeron interactions which produce a central systemX (composed mainly of multimeson states) in proton-proton collisions at \(\sqrt s \) at the CERN ISR. The systemX has a Feynman-x distribution which is sharply peaked atx _f=0, is inconsistent with any significant contributions from Reggeon exchange processes, and has an invariant mass dependence in good agreement with the predicted formM _x ^?2 . Kaon production is about 15% of pion production, nearly independent ofM _x, while proton-antiproton production averages about 5% of pion production and increases withM _x. The structure of the central systemX develops into a jetlike shape, asM _x increases, as would be expected from a model of Pomeron fragmentation. The shape of thex _f(π) distribution in the center of mass of theX system (although not proving existence) is consistent with asoft partonic substructure of the Pomeron.     

Use of capillary electrophoresis in drug quality assessment of synthetic porcine secretin

The purity profile for porcine secretin attributable to contamination by equilibrium products such as aspartoyl(3) secretin has been shown to be dependent on the pH of the analytical system. Capillary zone electrophoresis (CZE) methods have been developed for the efficient separation of synthetic porcine secretin, its equilibrium products and other impurities in aqueous solutions at both acidic and alkaline pH. These conditions are more representative of those used for the reconstitution and administration of porcine secretin, and good results cannot be achieved using HPLC due to poor peak shape above pH 5.8. The influence of various CZE operational parameters was systematically examined. The methods were validated for accuracy, precision, linearity, LOD and LOQ. A comparative evaluation of the stability of test solutions was determined using CZE and HPLC over a range of pH values. HPLC and CZE methods produced similar results at low pH.     

4-Aryloxybutenolides as "chiral aldehyde" equivalents: an efficient enantioselective synthesis of (+)-brefeldin a

4-(2'-Naphthoxy)-2-butenolide, readily available with high enantiopurity by a dynamic kinetic asymmetric transformation (DYKAT) of racemic 4-acyloxybutenolides (available in two steps from furfural), serves as an excellent chiral building block where the naphthoxy group strongly directs the stereochemistry of cycloadditions to the double bond. Notably, the cycloadditions of trimethylenemethanepalladium intermediates which do not exhibit good diastereoselectivity in additions to acceptors that possess many common and important chiral auxiliaries undergo cycloadditions with excellent regio- and stereocontrol. The utility of this process set the stage for an efficient new synthesis of (+)-brefeldin A, a compound of growing pharmacological significance. This synthesis also highlights the Pd-catalyzed DYKAT of crotyl carbonate to create the remote stereocenter. A new two-step method to convert aldehydes to delta-hydroxy-E-alpha,beta-enoates is also outlined.     

Tagging diquarks by protons of high transverse momentum inpp collisions at the ISR

Events are analyzed in which a high transverse momentum proton was produced at polar angles of 10°, 20° and 45°. The experiment was performed with the Split Field Magnet detector at the CERN ISR at \(\sqrt s \) =62 GeV. A 4-jet structure of these events is found [1]. The measured charge structure of spectator jets is compatible with proton production from hard diquark scattering. This is supported by a study of baryon number compensation in the towards jets. The observed charge compensation in the towards jets suggests dominance of hard (ud) scattering. Evidence forΔ ⁺⁺ production at high transverse momentum indicates the presence of an additional (uu) scattering component. The properties of the recoiling away jets are compatible with the fragmentation of a valence quark and/or of a gluon as in the case of meson triggers.     

Determination of impurities in tungsten metal: Determination of copper

A method is proposed for the determination of copper present as an impurity in tungsten. 2,9-dimethyl-1.10-phenanthroline forms a stable complex with the cuprous ion, which can be extracted by chloroform (in presence of alcohol) from aqueous solution and determined absorptiometrically. Tungsten is complexed with citric acid and phosphoric acid.