Modalities and quantum mechanics

Three approaches concerning the usage of modalities in the language of quantum mechanics were considered; Mittelstaedt and I built up a dialog semantics for modalities on a metalinguistic level, and a calculus of quantum modal logic is known that is complete and sound with respect to this dialogic semantics. Van Fraassen replaced the usual interpretation of quantum mechanics (with the projection postulate) by his modal interpretation based on a modal object language. Dalla Chiara translated a nonmodal object language for quantum mechanics and the appropriate quantum logic into a modal language. Specifically we are interested in the similarities and the differences of these three approaches.     

Asymmetric allylboration of alpha,beta-enals as a surrogate for the enantioselective synthesis of allylic amines and alpha-amino acids

[reaction: see text] Optically pure allylic amines have been synthesized from alpha,beta-unsaturated aldehydes via allylboration with (-)-B-allyldiisopinocampheylborane, followed by Overman rearrangement. By incorporating crotyl and alkoxyallylboration, functionalization at delta-position was readily accomplished. By applying this methodology, the synthesis of several chiral alpha-amino acids has been achieved.     

SYNTHESIS OF CHIRAL THIOCARBAMOYLPHOSPHINES DERIVED FROM AMINO ACIDS1

Abstract

The methylester hydrochlorides of the (S)-amino acids L-alanine (la), L-phenylalanine (1b), L-valine (1c) and L-lysine (1d) were converted to the corresponding isothiocyanates 2a-d by thiophosgenation. 2a-d react with secondary phosphines and phosphine oxides to give the thiocarbamoylphosphines 3a-d and P-oxides 4a, b.     

Ultrasonic fatigue tests with stabilized amplitude and controlled temperature

An attachment for fatigue testing was developed, complementary to a commercially available ultrasonic generator with a power of 200 W. The fundamental improvements are: a control system which stabilizes the fatigue amplitude, and a programming attachment which supplies ultrasonic fatigue pulses in order to prevent undesirable temperature rises caused by internal friction. Similar attachments were developed for generators with powers of 400, 1 000 and 2 500 W. These improved fatigue testing machines permit investigations concerning the fatigue behaviour of metals with a remarkably high degree of damping.     

Mass spectral determination of skeletal/cardiac actin isoform ratios in cardiac muscle

Skeletal and cardiac muscle contains actin isoforms that vary by two juxtaposed amino acids and two amino acid substitutions (Met299Leu and Ser358Thr). This close sequence homology does not allow cardiac and skeletal actin isoforms to be resolved in traditional SDS-PAGE analysis as the molecular weights (Deltamass = 32 Da) are not significantly different and the pIs are identical (5.2). Although cardiac actin is the predominant form in cardiac muscle, there appears to be a specific skeletal/cardiac actin ratio in a normal heart that may vary in a compromised or diseased heart. In an effort to ascertain the validity of this hypothesis we developed a mass spectrometric technique to measure the ratio of skeletal to cardiac actin. The technique involves purification of muscle actin and subsequent liquid chromatography coupled with electrospray ionization Fourier transform ion cylcotron resonance (LC/FTICR-MS) mass spectrometry. A 7 Tesla FTICR mass spectrometer was utilized to compare skeletal/cardiac actin isoform ratios. Additionally, a new dual electrospray ionization source was employed to determine accurate masses of the alpha-skeletal and alpha-cardiac actins.     

The effects of sample preparation methods on the variability of the electrospray ionization response for model drug compounds

A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd.     

Multiple Ligand and Cell-Dependent States of Lateral Mobility of Plasmalemmal G Protein-Coupled Cholecystokinin Receptors

Lateral movement of receptor molecules in the plane of the plasmalemma has important implications for signal transduction and receptor regulation, yet mechanisms affecting such movement are not well understood. We have studied the lateral mobility of the G protein-coupled cholecystokinin (CCK) receptor expressed in the natural milieu of the rat pancreatic acinar cell and in a model cell system, the CHO-CCKR cell, after occupation with fluorescent agonist and antagonist. Lateral diffusion characteristics were distinct in each type of cell and for receptors occupied by each type of ligand, fluorescent agonist, rhodamine-Gly-[(Nle^28,31)CCK-26-33], and fluorescent antagonist, rhodamine-Gly-[(D-Trp³⁰,Nle^28,31)CCK-26-32]-phenethyl ester. Multiple states of mobility were detected for CCK receptors. The slowest population of mobile receptors on the CHO-CCKR cells moved at similar rates when occupied by both antagonist and agonist, while the faster-moving populations moved at a faster rate when occupied with antagonist than with agonist. The fastest component of mobile receptors may reflect unconstrained interactions of the antagonist-occupied receptors with signaling or anchoring structures, while the slowest component may represent the fraction of ligand-occupied receptors that ultimately undergo internalization. The intermediate mobility states may reflect receptor interactions with signal transduction and regulatory machinery. While only a single population of mobile receptors was demonstrable on the acinar cells, increased ligand concentrations (agonist and antagonist) resulted in increased percentages of mobile receptors, suggesting a stoichiometric limitation of immobilizing molecular constraints. Inhibition of protein kinase C had no significant effect on the lateral mobility of agonist-occupied CCK receptors.     

Gamma-ray spectroscopy with relativistic exotic heavy-ions

Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors (segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed.