Pyrolysis of carbonaceous foundry sand additives: Seacoal and gilsonite

Seacoal and gilsonite are used by the foundry industry as carbonaceous additives in green molding sands. In this study, pyrolysis was used to simulate the heating conditions that the carbonaceous additives would experience during metal casting. Gas chromatography–mass spectrometry was used to tentatively identify major organic products generated during their pyrolysis at 500, 750, and 1000 °C. A number of compounds of environmental concern were identified during the pyrolysis of seacoal and gilsonite, including substituted benzenes, phenolics, and polycyclic aromatic hydrocarbons (PAHs). These thermal decomposition products, and especially PAHs, were generated at each pyrolysis temperature in all foundry sands containing seacoal. In gilsonite-amended sand, however, mainly alkanes and alkenes were identified at 500 and 750 °C and PAHs at 1000 °C. Compared to seacoal, the most intense peaks occurred during the pyrolysis of sand containing gilsonite. The greatest loss of pyrolyzable material also occurred during heating of gilsonite-amended sand from ambient temperature to 1000 °C in a thermogravimetric analyzer. The results obtained from this study will be useful to green sand foundries looking to reduce volatile hydrocarbon emissions.     

A flexible, self-contained germanium spectrometer for the in-situ measurement of gamma-ray emitting radionuclides in and around piping

In order to certify that process and drain lines which had been used for transporting radioactive materials, and their surrounding environments, are now free of residual contamination, it is both desirable and cost effective to make in situ measurements during the decontamination and decommissioning process. A 4.83-cm diameter modular proble consisting of a liquid nitrogen reservoir, a preamplifier, and a high-resolution germanium gamma-ray spectrometer with flexible connections between the modules has been developed for the measurement of gamma rays in and around piping. The assembly is sufficiently flexible to navigate through a “3-inch diameter p-trap.” The probe design and specifications are discussed. Results from an application are presented.     

On perspective errors in endoscopic PIVSur les erreurs de perspective dans PIV endoscopique

Results are presented from a single and dual lens endoscopic PIV imaging system with a view to application of PIV where optical access is restricted such as internal flows. The dual lens PIV images were processed using cross-correlation, a cubic mapping function and standard stereoscopic relationships. For the single lens system, the images were processed using cross-correlation and a quadratic distortion-mapping function. Results have shown the single lens system to have in-plane errors an order of magnitude greater than the stereoscopic dual lens endoscopic PIV system. These errors are generated by perspective effects. Use of the stereo arrangement is therefore recommended wherever quantitative 3D velocimetry data is acquired using an endoscopic system. To cite this article: M. Reeves, N.J. Lawson, C. R. Mecanique 332 (2004).     

Detection of human and rodent 5-HT3B receptor subunits by anti-peptide polyclonal antibodies

Background  

The 5-HT₃ receptor is a member of a neurotransmitter-gated ion channel family which includes nicotinic acetylcholine, GABA_A, and glycine receptors. While antibodies specific for the 5-HT_3A receptor subunit are plentiful, and have revealed a wealth of structural and functional information, few antisera exist for the detection of 5-HT_3B receptor subunits. Here we describe the generation and characterisation of a rabbit polyclonal antiserum that specifically recognises 5-HT_3B receptor subunits     

Statistical analysis of local search landscapes

This paper discusses the application of some statistical estimation tools in trying to understand the nature of the combinatorial landscapes induced by local search methods. One interesting property of a landscape is the number of optima that are present. In this paper we show that it is possible to compute a confidence interval on the number of independent local searches needed to find all optima. By extension, this also expresses the confidence that the global optimum has been found. In many cases, this confidence may be too low to be acceptable, but it is also possible to estimate the number of optima that exist. Theoretical analysis and empirical studies are discussed, which show that it may be possible to obtain a fairly accurate picture of this property of a combinatorial landscape. The approach is illustrated by analysis of an instance of the flowshop scheduling problem.     

Selective trapping of SNO-BSA and GSNO by benzenesulfinic acid sodium salt: mechanistic study of thiosulfonate formation and feasibility as a protein S-nitrosothiol detection strategy

The conversion of S-nitrosothiols to thiosulfonates by reaction with the sodium salt of benzenesulfinic acid (PhSO₂Na) has been examined in detail with the exemplary substrates S-nitrosoglutathione (GSNO) and S-nitrosylated bovine serum albumin (SNO-BSA). The reaction stoichiometry (2:1, PhSO₂Na:RSNO) and the rate law (first order in both PhSO₂Na and RSNO) have been determined under mild acidic conditions (pH 4.0). The products have been identified as the corresponding thiosulfonates (GSSO₂Ph and BSA-SSO₂Ph) along with PhSO₂NHOH obtained in a 1:1 ratio. GSH, GSSG, and BSA were unreactive to PhSO₂Na.     

Catalytic asymmetric hydrogenation of heterocyclic ketone-derived hydrazones, pronounced solvent effect on the inversion of configuration

An enantioselective hydrogenation of hydrazones derived from heterocyclic ketones was developed with up to 85% ee. The enantiomeric purity was enriched to >99% ee by crystallization from EtOAc in >80% yield. Optimization studies have revealed a notable solvent effect that resulted in inversion of enantioselectivity from 85% ee in MeOH to −27% ee in DCE. The hydrazone geometry and possible hydrogenation via endocyclic alkene were examined as possible factors for the inversion of enantioselectivity.     

Glassy behavior in a binary atomic mixture

We experimentally study one-dimensional, lattice-modulated Bose gases in the presence of an uncorrelated disorder potential formed by localized impurity atoms, and compare to the case of correlated quasidisorder formed by an incommensurate lattice. While the effects of the two disorder realizations are comparable deeply in the strongly interacting regime, both showing signatures of Bose-glass formation, we find a dramatic difference near the superfluid-to-insulator transition. In this transition region, we observe that random, uncorrelated disorder leads to a shift of the critical lattice depth for the breakdown of transport as opposed to the case of correlated quasidisorder, where no such shift is seen. Our findings, which are consistent with recent predictions for interacting bosons in one dimension, illustrate the important role of correlations in disordered atomic systems.     

Near field optical spectroscopy of colored centers stripes written in lithium fluoride by electron-beam lithography

Electron-beam lithography has been used to define color center stripes of about one hundred micrometers length and variable width (100 v nm to 5 v m) in lithium fluoride. These structures have for the first time been illustrated and spectrally characterized in near field optical microscopy (SNOM) operating in local illumination mode with an optical fiber probe and far field fluorescence detection.