Derivations and the integral closure of ideals

Let be a complete local domain containing the rationals. Then there exists an integer such that for any ideal , if , , then there exists a derivation of with .

     

Luminescence Characterization of a Novel, Hydrophobically Modified and Heavy Atom-Functionalized, Water-Soluble Polymer

A hydrophobically modified water-soluble polymer, based upon acrylic acid and styryl derivatives, was synthesized. A proportion (ca. 75 mol%) of the styryl residues in the copolymer contain a bromine substituent as a heavy-atom functionality. It has been shown that room-temperature phosphorescence (RTP) can be induced in an acenaphthylene (ACE) label, covalently bound to the polymer chain, through intramacromolecular interactions in dilute solutions of the copolymer. This is the first instance in which RTP has been generated in either label or solubilized guest, in such a fashion. The conformational behavior of the functionalized copolymer, BrSTY/STY/AA, has been studied using RTP, fluorescence lifetime, and time-resolved anisotropy measurements and compared to that of both its unbrominated, styrene-modified analogue, STY/AA, and poly(acrylic acid) PAA itself. The conformation transition which accompanies conversion of each polyacid into the corresponding fully neutralized polysalt is much more dramatic in either hydrophobically modified species than in poly(acrylic acid). Intramacromolecular aggregation leading to the creation of hydrophobic domains within the coils of the macromolecules is enhanced at a low pH and severely impedes segmental motion in the two styrene-modified polyacids. The effect is greater in the bromine-containing polymer, which suggests that more densely packed domains are formed in this species than in STY/AA. In addition to altering the magnitude of the effect that neutralization has upon the molecular dynamics of the polyacid in aqueous media, hydrophobic modification raises the pH range over which the change in conformational behavior of the macromolecule is apparent.     

Activation analysis of halogens in photographic emulsions using a252Cf neutron multiplier

A nondestructive neutron activation technique for the simultaneous direct determination of chlorine, bromine, and iodine in silver halide mixtures is described using a²⁵²Cf neutron multiplier (CFX). About 5–50 mg of sample are used. The analysis is semiroutine, without the need for a monitor included with each sample since the flux stability and reproducibility are within ±1%, decaying only with the 2.65 year half-life of²⁵²Cf. The precision and accuracy are counting-statistics controlled and are generally ±1% RSD or better. The method offers an attractive alternative to existing chemical and instrumental methods for these determinations in silver halide mixtures because it has the potential for providing reasonably rapid analyses with good precision and accuracy.     

An automated high performance capillary liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometer for high-throughput proteomics

We describe a fully automated high performance liquid chromatography 9.4 tesla Fourier transform ion resonance cyclotron (FTICR) mass spectrometer system designed for proteomics research. A synergistic suite of ion introduction and manipulation technologies were developed and integrated as a high-performance front-end to a commercial Bruker Daltonics FTICR instrument. The developments incorporated included a dual-ESI-emitter ion source; a dual-channel electrodynamic ion funnel; tandem quadrupoles for collisional cooling and focusing, ion selection, and ion accumulation, and served to significantly improve the sensitivity, dynamic range, and mass measurement accuracy of the mass spectrometer. In addition, a novel technique for accumulating ions in the ICR cell was developed that improved both resolution and mass measurement accuracy. A new calibration methodology is also described where calibrant ions are introduced and controlled via a separate channel of the dual-channel ion funnel, allowing calibrant species to be introduced to sample spectra on a real-time basis, if needed. We also report on overall instrument automation developments that facilitate high-throughput and unattended operation. These included an automated version of the previously reported very high resolution, high pressure reversed phase gradient capillary liquid chromatography (LC) system as the separations component. A commercial autosampler was integrated to facilitate 24 h/day operation. Unattended operation of the instrument revealed exceptional overall performance: Reproducibility (1-5% deviation in uncorrected elution times), repeatability (<20% deviation in detected abundances for more abundant peptides from the same aliquot analyzed a few weeks apart), and robustness (high-throughput operation for 5 months without significant downtime). When combined with modulated-ion-energy gated trapping, the dynamic calibration of FTICR mass spectra provided decreased mass measurement errors for peptide identifications in conjunction with high resolution capillary LC separations over a dynamic range of peptide peak intensities for each spectrum of 10(3), and >10(5) for peptide abundances in the overall separation.     

Applications of time-resolved anisotropy measurements to the study of molecular mobility and order in polymer systems

The applications of luminescence anisotropy (especially time-resolved measurements) in polymer science are discussed. In this brief overview of the area, particular attention is paid to investigations of polymer dynamics and ordering in dilute solution and aqueous dispersions. The account is illustrated with examples from recent studies in the authors' laboratories.     

The Characterization of a Neutron Radiography Triga Reactor for NAA of Chlorine in an Iron Oxide Matrix

An irradiation position in the 250 kW Triga reactor was characterized for instrumental neutron activation analysis of chlorine in an iron oxide matrix. Factors that affect the accuracy of the determination include variations in the reactor neutron spectrum and flux as a function of spatial position and the presence of chlorine impurities. Gold wire and foils were used to determine the neutron flux and cadmium ratio as a function of height in an air-filled irradiation tube.     

Randomized Acquisition for the Suppression of Systematic F1 Artifacts in Two-Dimensional NMR Spectroscopy

2D spectra, particularly for homonuclear correlation, can show a variety of artifactual signals in the F₁ domain. Common sources include carry-over of signal modulation from one transient to the next (“rapid pulsing artifacts”) and systematic variations in room temperature (“parallel diagonals”). In both cases there is one very simple expedient which can greatly reduce the impact of these sources of error. Multidimensional data sets are almost invariably recorded by simply incrementing or decrementing evolution periods, largely for reasons of convenience and historical precedent. If instead the sampling of the evolution periods is carried out in random order, the perturbations responsible for the sharp F₁ signals in the conventional experiment manifest themselves as t₁ noise. Since the randomized acquisition redistributes coherent artifactual signals randomly in F₁, the maximum artifactual signal is substantially reduced in the randomized experiment and no longer appears in the form of misleading distinct peaks.     

Thermodynamische Analyse der Dehnung des elastischen Gewebes vom Standpunkt der statistisch-kinetischen Theorie der Kautschukelastizität.

Ohne Zusammenfassung Herrn Prof. Dr. W. J. Schmidt, Gieβen, zum 60. Geburtstag gewidmet.