Mass spectrometry of pancuronium bromide and related quaternary ammonium steroids using the moving belt LC/MS interface

Pancuronium and vecuronium are members of a series of quaternary ammonium steroids used as neuromuscular blocking agents in anesthesiology. In this study the mass spectrometric properties of these bromide salts are examined and spectral features which permit their differentiation are evaluated. The relative merits of chemical ionization and fast atom bombardment using the moving belt liquid chromatography/mass spectrometry interface have been investigated. Fragmentation pathways for both ionization methods were determined with deuterium labeling and linked-scan techniques. Cleaner spectra can be obtained via the matrix-free belt introduction system as compared to conventional fast atom bombardment.     

Determination of the average lifetime of bottom hadrons

We have determined the average lifetime of hadrons containing b quarks produced in e⁺e^? annihilation to be

$\text{τ}\text{B}\text{=}\text{1.83}\text{+0.83}\text{+0.37}\text{?}\text{?0.34}\text{×10}{}^{\mathrm{?12}}\text{s}$

. Our method uses charged decay products from both non-leptonic and semileptonic decay modes.     

Development of a systems analysis approach for resolving the structure of biodegrading soil systems

An experimental and mathematical method is developed for the microbial systems analysis of polyaromatic hydrocarbon (PAH)-degrading mixed cultures in PAH-contaminated “town gas” soil systems. Frequency response is the primary experimental and data analysis tool used to probe the structure of these complicated systems. The objective is to provide a fundamental protocol for evaluating the performance of specific mixed microbial cultures on specific soil systems by elucidating the salient system variables and their interactions. Two well-described reactor systems, a constant volume stirred tank reactor (CSTR) and a plug flow differential volume reactor, are used in order to remove performance effects that are related to reactor type as opposed to system structure. These two reactor systems are well-defined systems that can be described mathematically and represent the two extremes of one potentially important system variable, macroscopic mass transfer. The experimental and mathematical structure of the protocol is described, experimental data is presented, and data analysis is demonstrated for the stripping, sorption, and biodegradation of napththalene.     

A double-twist Möbius-aromatic conformation of [14]annulene

[structure: see text] B3LYP and KMLYP/6-31G(d) calculations predict a double-helical and chiral conformation of [14]annulene with the topological properties of a double-twist M?bius band as highly aromatic; its energy with respect to the known Hückel-aromatic conformation is predicted to be stabilized by suitable ring substitution.     

Colorimetric determination of osmium (VI) with 1-naphthylamine-3,5,7-trisulfonic acid

An investigation has been made of the organic compound, 1-naphthylamine-3,5,7-trisulfonic acid, for use as a colorimetric reagent for the determination of trace quantities of osniiun(Vl). When this compound is added to an osmium (OsO₄^-2) solution, a violet colored organo-osmium complex is formed which has highest sensitivity at wavelength 560 mμ. The complex reaches maximum color intensity after four hours. The solution should be brought to pH 1.5 and maintained at tins pH with a buffer, after maximum color development. The colored complex conforms to Beer's law over an osmium concentration range of 0 to 6 p.p.m. Its absorbance is not affected by either excess reagent (up to a 7 : 1 ratio) or by temperature variation over the range 15° to 35° C. Many metallic ions interfere with the color reaction and hence require a separation, of osmium from these ions.The nature of the complex in solution was studied by the following three methods: (1) mole ratio, (2) continuous variations and (3) slope ratio. All three methods indicate a ratio of reagent to osmium of 2 to 1.A procedure for the colorimetric determination of osmium(VI) has been developed; it has a sensitivity of 1 part osmium in 15,000,000 parts of solution, with good precision.     

Cyclo dehydration reaction of polyhydrazides. II. Kinetic parameters obtained from isothermal thermogravimetry

The kinetics of the thermal conversion reaction of poly-(1,3-phenyl-1,4-phenyl)-hydrazide into poly-(1,3-phenyl-1,4-phenyl)-1,3,4-oxadiazole have been studied with isothermal thermogravimetry in continuation of a study with nonisothermal thermogravimetry described in a previous paper. Although the isothermal measurements are much more time-consuming, they provide some new information and insight about the cyclo dehydration reaction of the polyhydrazide. The physical state of the sample, rubbery or glassy, seems to influence the kinetics considerably. The kinetic parameters determined with the isothermal method for the polymer in its glassy state agree well with the parameters derived from the previously reported nonisothermal measurements, while the kinetic parameters for the expected rubbery state differ considerably. The morphological state or the history of the polymer has also a considerable influence on the kinetics of the isothermal conversion process. The powder form of the polymer has a much lower isothermal conversion rate than the film form.     

A chemical inhibitor reveals the role of Raf kinase inhibitor protein in cell migration

Raf kinase inhibitor protein (RKIP) is a modulator of cell signaling that functions as an endogenous inhibitor of multiple kinases. We demonstrate here a positive role for RKIP in the regulation of cell locomotion. We discovered that RKIP is the relevant cellular target of locostatin, a cell migration inhibitor. Locostatin abrogates RKIP's ability to bind and inhibit Raf-1 kinase, and it acts by disrupting a protein-protein interaction, an uncommon mode of action for a small molecule. Small interfering RNA-mediated silencing of RKIP expression also reduces cell migration rate. Overexpression of RKIP converts epithelial cells to a highly migratory fibroblast-like phenotype, with dramatic reduction in the sensitivity of cells to locostatin. RKIP is therefore the compound's valid target and a key regulator of cell motility.     

Intermolecular perturbation of CH-stretching diagonal local-mode anharmonicity in 3-methylpentane

CH-stretching overtone spectra of 3-methylpentane are measured for both liquid and low temperature (77 K) solid phases. A local-mode analysis is used to extract the diagonal local-mode anharmonicity constant. The results show that the local vibrational potential is more harmonic at high viscosity.     

Directed evolution of the dioxygenase complex for the synthesis of furanone flavor compounds

Herein we report a new preparation of 4-hydroxy-2,5-dimethyl-2,3-dihydrofuran-3-one, the flavor compound strawberry furanone, based on a ‘green’ approach with a minimum number of steps. The first step is an enzymatic dioxygenation of p-xylene to form cyclohexadiene-cis-diol, followed by ring opening via ozonolysis, and ring closure to form the furanone. In efforts to improve the efficiency of the enzymatic step, a directed evolution approach was taken to increase the substrate specificity and selectivity of the toluene dioxygenase enzyme system.     

Geometry of optimality conditions and constraint qualifications: The convex case

The cones of directions of constancy are used to derive: new as well as known optimality conditions; weakest constraint qualifications; and regularization techniques, for the convex programming problem. In addition, the badly behaved set of constraints, i.e. the set of constraints which causes problems in the Kuhn—Tucker theory, is isolated and a computational procedure for checking whether a feasible point is regular or not is presented.This research was supported by the National Research Council of Canada and le Gouvernement du Quebec and is part of the author's Ph.D. Dissertation done at McGill University, Montreal, Que., under the guidance of Professor S. Zlobec.