Semi‐automated tandem mass spectrometric (MS/MS) triple quadrupole operating parameter optimization for high‐throughput MS/MS detection workflows

This paper describes an automated workflow for the determination of selected reaction monitoring (SRM) transitions and optimum mass spectrometric (MS) instrument parameters. The approach uses a Nanomate from Advion Biosciences for automated infusion of small amounts of sample in combination with Automaton optimization software from Sciex. The results are stored in the Analyst software Compound Database for automated acquisition method building. Comparisons are presented between the more traditional optimization methods of manual flow injection optimization, Autotune infusion optimization, Automaton flow injection optimization and the Nanomate–Automaton optimization approach. Data is also presented to show that acquisition methods developed on the Sciex model API3000 instrument can be effectively transferred to the Sceix API4000 and API5000 model instruments. Copyright © 2009 John Wiley & Sons, Ltd.     

The interference of resonance states of model one-dimensional systems

The interference of resonances and formation of so-called bound states in the continuum were considered for the examples of numerical modeling of two-and three-channel one-dimensional systems. It was shown that intrachannel resonances virtually did not interact either with each other or with resonances formed in the binding of open and closed channels. Conversely, the interference of two resonances each formed in the binding of an open and closed channel resulted in the appearance of bound states in the continuum under certain conditions. The reliability of the complex rotation method for calculating isolated resonances and resonances bound to a complex was demonstrated.     

General method for producing a boundary-fitted orthogonal curvilinear mesh

A general method is described for computing an orthogonal mesh fitted to a two-dimensional physical domain with arbitrary closed boundary. The method allows optimum control of mesh spacing through the introduction of arbitrary (with weak constraints) ‘packing’ functions into the elliptic governing equations. Two particular aspects are addressed: first, the condition on a scaling factor which normalizes the mesh aspect ratio; second, the condition for avoiding run-out of the mesh beyond the boundaries of the physical domain.Conversion of the equations to finite difference form and appropriate iterative techniques are discussed. Finally applications of the method in the context of flow across a bundle of rods are presented.     

Poly(diphenylsiloxy)arylazines. I. Synthesis and characterization

The synthesis of poly(diphenylsiloxy)arylazines and the preparation of the necessary aromatic aldehyde and azine precursors are described. This new family of polymers was prepared by a modified melt-condensation reaction of hydroxyl-substituted phenyl-and naphthylazines with bis(anilino)diphenylsilane. The resulting polymers have been characterized by elemental analysis, gel-permeation chromatography, vapor-phase osmometry, and absorption spectroscopy. Assignment of a polymer backbone composed of alternating diphenylsiloxane and arylazine moieties was made on the basis of the infrared absorption bands and by comparison of the fluorescence and absorption spectra of the polymers with those of model compounds. The molecular weight of the polymers was found to depend on temperature, reaction time, and the ratio of monomers. The formation of low molecular weight products was avoided by maintaining reaction temperatures below the decomposition point of the arylazine and by keeping the ratio of silylamine to arylazine at about 3:1. Molecular weights as high as 38,000 and extents of conversion of 85% were obtained by the described melt condensation procedure. The molecular weight of another member of the family was increased from 4600 to 8100 by a post-polymerization scheme, involving the reaction of aromatic hydroxyl and anilinosilane endgroups. Significant crosslinking via ortho hydroxyl groups during the polymerization of tetrahydroxyarylazines can be ruled out because of the solubility of the polymers in chloroform or tetrahydrofuran and on the basis of their fluorescence spectrum.     

Adsorptions- und Kontaktwinkel-Studien. II. Wasser und organische Substanzen an poliertem Polytetrafluor?thylen

Ohne Zusammenfassung     

Measurement of the viscosity-density product using multiple reflections of ultrasonic shear horizontal waves

We have developed an on-line computer-controlled sensor, based on ultrasound reflection measurements, to determine the product of the viscosity and density of a liquid or slurry for Newtonian fluids and the shear impedance of the liquid for non-Newtonian fluids. A 14 MHz shear wave transducer is bonded to one side of a 45-90 degrees fused silica wedge and the base is in contract with the liquid. Twenty-eight echoes were observed due to the multiple reflections of an ultrasonic shear horizontal (SH) wave within the wedge. The fast Fourier transform of each echo was obtained for a liquid and for water, which serves as the calibration fluid, and the reflection coefficient at the solid-liquid interface was obtained. Data were obtained for 11 sugar water solutions ranging in concentration from 10% to 66% by weight. The viscosity values are shown to be in good agreement with those obtained independently using a laboratory viscometer. The data acquisition time is 14s and this can be reduced by judicious selection of the echoes for determining the reflection coefficient. The measurement of the density results in a determination of the viscosity for Newtonian fluids or the shear wave velocity for non-Newtonian fluids. The sensor can be deployed for process control in a pipeline, with the base of the wedge as part of the pipeline wall, or immersed in a tank.     

Laser diagnostics of nanoscale dielectric films on transparent substrate by integrating differential reflectivity and ellipsometry

The effect of nanometer dielectric films on the differential reflection characteristics of linearly polarized light from non-absorbing materials is investigated in the long-wavelength approximation. The second-order formulas for changes in the reflectance of s- and p-polarized light caused by ultrathin layer are obtained. A detailed analysis of the influence of ultrathin film to the reflectivity of p-polarized light in the vicinity of the Brewster angle is carried out. The novel methods are developed for determining the thickness and refractive index of uniform (or the average values of refractive index of nonuniform) nanometer-scale films by differential reflectivity and ellipsometric measurements.     

Single Step Syntheses of ω-9-Fluorenylmethyl Esters of Aspartic and Glutamic Acids

Base lability of the 9-fluorenylmethyl ester makes this group useful in solid phase peptide synthesis when used in combination with the tBoc methodology for preparing cyclic peptides. We describe a simple one step synthesis of the 9-fluorenylmethyl esters of aspartic and glutamic acids.     

Functionalized single graphene sheets derived from splitting graphite oxide

A process is described to produce single sheets of functionalized graphene through thermal exfoliation of graphite oxide. The process yields a wrinkled sheet structure resulting from reaction sites involved in oxidation and reduction processes. The topological features of single sheets, as measured by atomic force microscopy, closely match predictions of first-principles atomistic modeling. Although graphite oxide is an insulator, functionalized graphene produced by this method is electrically conducting.     

Hydrazone- and hydrazide-containing N-substituted glycines as peptoid surrogates for expedited library synthesis: application to the preparation of Tsg101-directed HIV-1 budding antagonists

Replacing the Pro6 in the p6(Gag)-derived 9-mer "P-E-P-T-A-P-P-E-E" with N-substituted glycine (NSG) residues is problematic. However, incorporation of hydrazone amides ("peptoid hydrazones") can be readily achieved in library fashion. Furthermore, reduction of these hydrazones to N-substituted "peptoid hydrazides" affords a facile route to library diversification. This approach is demonstrated by application to Tsg101-binding compounds designed as potential HIV budding antagonists. [reaction: see text]