Enhancing the intensities of lysine-terminated tryptic peptide ions in matrix-assisted laser desorption/ionization mass spectrometry

Tryptic digests of three proteins are reacted with O-methylisourea in order to convert lysine residues to homoarginines. The resulting homoarginine-terminated peptides exhibit more intense MALDI mass spectral peaks than their lysine-terminated predecessors. This simple chemical reaction should therefore facilitate protein sequencing and mass mapping.     

Studies of the Fermi surface of V3Si by 2D ACAR measurements

We report two-dimensional angular correlation of annihilation radiation (2D ACAR) measurements using positrons in single crystals of V₃Si. Anisotropic structure commensurate with the reciprocal lattice is observed and attributed to the complex Fermi surface (FS). A simple geometrical model for the FS is developed and compared with folded ACAR distributions. The results of a 3D reconstruction are compared with recent band calculations.     

Studies in qualitative inorganic analysis. Part XLI

Summary The solubility of mercury(II) sulphide in the various reagents used to separate the copper-tin group has been quantitatively investigated. Our results show that with all reagents the solubility of mercury(II) sulphide is largest when tin(IV) and molybdenum(VI) are present and that the use of hydrogen peroxide with potassium hydroxide ensures that at least 95% of the mercury appears in the copper group.

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Zusammenfassung Die Löslichkeit von Queoksilber(II)-sulfid in den verschiedenen, zur Trennung der Kupfer-Zinn-Gruppe verwendeten Reagenzien wurde quantitativ überprüft. Diese Löslichkeit ist dann in allen Reagenzien am größten, wenn Zinn(IV) und Molybdän(VI) zugegen sind. Die Anwendung von Wasserstoffperoxid und Kalilauge gibt die Gewähr, daß mindestens 95% des Quecksilbers in der Kupfergruppe zu finden sind.

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Part XL: Mikrochim. Acta [Wien] 1970, 83.     

Effects of polydispersity on the order-disorder transition of diblock copolymer melts

The effect of polydispersity on an AB diblock copolymer melt is investigated using lattice-based Monte Carlo simulations. We consider melts of symmetric composition, where the B blocks are monodisperse and the A blocks are polydisperse with a Schultz-Zimm distribution. In agreement with experiment and self-consistent field theory (SCFT), we find that polydispersity causes a significant increase in domain size. It also induces a transition from flat to curved interfaces, with the polydisperse blocks residing on the inside of the interfacial curvature. Most importantly, the simulations show a relatively small shift in the order-disorder transition (ODT) in agreement with experiment, whereas SCFT incorrectly predicts a sizable shift towards higher temperatures.     

The separation and determination of fatty acids by isotopic dilution and radiogas-liquid chromatography

A number of static phases have been evaluated for the GLC separation of fatty acids. Of those investigated, only AT 1200 was capable of resolving the isomeric forms of the acids. A radiogas-liquid chromatographic method incorporating isotopic dilution analysis has been developed for the determination of n-butyric acid. The proposed method has been applied to the determination of the acid in hydrolysed butter fat and milk chocolate extracts.     

Chaotic Expansion of Elements of the Universal Enveloping Algebra of a Lie Algebra Associated with a Quantum Stochastic Calculus

The functional Ito formula, in the form df() = f( + d ) –f(),is formulated and proved in the context of a Lie algebra L associatedwith a quantum (non-commutative) stochastic calculus. Here fis an element of the universal enveloping algebra U of L, andf() + d() – f() is given a meaning using the coproductstructure of U even though the individual terms of this expressionhave no meaning. The Ito formula is equivalent to a chaoticexpansion formula for f() which is found explicitly. 1991 MathematicsSubject Classification: primary 81S25; secondary 60H05; tertiary18B25.     

An Experimental Study of Inertial Waves in a Closed Cone

An experimental study of inertial waves in a closed cone is presented in which the inertial waves are excited by a slight periodic oscillation superimposed on the cone's basic rotation rate. The dynamic pressure field is measured along the cone's rotation axis; no standing modal structure is observed, confirming Greenspan's (1969) argument that the closed cone appears open to inertial oscillations and the inertial wave spectrum is continuous. Similar pressure measurements made in the frustum of a right circular cone show that removal of the singular apex of the cone leads to standing wave modes.