The effect of stoichiometry on the ignition behaviour of synthetic pyrrhotites

A series of pyrrhotites of various stoichiometries was synthesized and characterized, and fractionated into four particle size ranges. The ignition temperatures and extent of reaction were determined by a thermogravimetric method. These measurements enabled the effect of stoichiometry and particle size on the ignition temperature and extent of oxidation to be established. The trends observed in the ignition behaviour are consistent with the concept of sulfur evolution being the key to the initiation of the ignition reaction.

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Zusammenfassung Es wurde eine Reihe Pyrrhotine unterschiedlicher Zusammensetzung hergestellt, beschrieben und nach Partikelgröße in vier Fraktionen zerlegt. Zündungstemperatur und Reaktionsausmaß wurden thermogravimetrisch bestimmt. Durch diese Messungen wurde es ermöglicht, den Einfluß von Stöchiometrie und Partikelgröße auf Zündungstemperatur und Oxidationsausmaß zu schätzen. Die beim Zündungsverhalten beobachteten Tendenzen stimmen mit dem Konzept überein, wonach die Freisetzung von Schwefel zum Einsetzen der Zündungsreaktion führt.

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We are grateful to Dr. B. Robinson of the CSIRO Division of Mineral Products, Perth, for making available the microprobe equipment and assisting in the collection of data.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

Determination of cefotaxime and desacetylcefotaxime in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the analysis of the anti-bacterial agent cefotaxime and desacetylcefotaxime in physiological fluids. Plasma or serum samples were mixed with chloroform--acetone to remove proteins and most lipid material. The aqueous phase was then freeze-dried, reconstituted in mobile phase and chromatographed on a reversed-phase column using UV detection at 262 nm. Urine was analysed directly after centrifugation to remove particulate matter. The detection limit was 0.5--1.0 micrograms/ml for serum and 5 micrograms/ml for urine. The method has been applied to the analyses of cefotaxime and desacetylcefotaxime in plasma, serum, urine, cerebrospinal fluid, saliva, and pus from infected wound secretions. Two additional metabolites, which are lactones in which the beta-lactam ring has been opened, could be separated by this method.     

Chlorination of uranium metal in molten NaCl-CaCl2 via bubbling HCl

Journal of Radioanalytical and Nuclear Chemistry - Molten chloride salt fast reactors (MCFRs) will require UCl3 dissolved in molten salt mixtures as fuel for nuclear fission. For infusing the salt...     

A non-destructive internal nuclear forensic investigation at Argonne: discovery of a Pu planchet from 1948

A plutonium alpha standard dating from 1948 was discovered at Argonne National Laboratory and characterized using a number of non-destructive analytical techniques. The principle radioactive isotope was found to be ²³⁹Pu and unique ring structures were found across the surface of the deposition area. Due to chronological constraints on possible sources and its high isotopic purity, the plutonium in the sample was likely produced by the Oak Ridge National Lab X-10 Reactor. It is proposed that the rings are resultant through a combination of polishing and electrodeposition, though the hypothesis fails to address a few key features of the ring structures.

     

Reversible carboxamide-mediated internal activation at C(6) of 2-chloro-4-anilino-1H-pyrrolo[2,3-d]pyrimidines

A synthetic route to bisanilino-1H-pyrrolo[2,3-d]pyrimidines has been discovered, wherein the C(6)-chloride reactivity is necessarily enhanced via reversible acid-catalyzed internal activation of the pyrimidine ring by a C(1')-carboxamide moiety. Subsequent selective nucleophilic displacements at C(6) and C(1') constitute a one-pot tandem protocol for the rapid assembly of bisanilino-1H-pyrrolo[2,3-d]pyrimidines.     

Azafullerenes encapsulated within single-walled carbon nanotubes

Methods of insertion of azafullerenes in single-walled carbon nanotubes (SWNTs) at different temperatures were investigated, while the effects of the conditions applied on the structure of azafullerene-based peapods, namely, C59N@SWNTs, were explored. Morphological characteristics of C59N@SWNTs were assessed and evaluated by means of high-resolution transmission electron microscopy (HR-TEM). Pathways and chemical reactions that occur upon encapsulation of C59N within SWNTs were evaluated. Monomeric azafullerenyl radical C59N. as inserted into SWNTs at high temperature, from purified (C59N)2 in the gas phase, can undergo a variety of different transformations forming dimers, oligomers or existing in its monomeric form inside SWNTs due to the stabilization effect by nanotube side walls. However, under milder conditions, that is, at lower temperature, bisazafullerene (C59N)2 can be inserted into SWNTs in its pristine dimeric form.     

Terahertz radiation from a nonlinear slab traversed by an optical pulse

We report on the theoretical calculations considering collinear electromagnetic radiation at the propagation of an optical pulse through a slab of nonlinear material. Calculated waveforms of the radiated field fit well to the experimental dependencies showing the remarkable similarities between the radiation at nonlinear wave interaction and the radiation phenomena of moving external charges, similarly to discussed in the Tamm Problem and transition radiation of moving external charges.     

Identification of hydrolytic metabolites of dyfonate in alkaline aqueous solutions by using high performance liquid chromatography – UV detection and gas chromatography-mass spectrometry

Organophosphorus compounds, becoming the most commonly used pesticides in agriculture, are garnering more interest to be environment and health issues associated with their usage. These compounds run-off into surface water and leach into groundwater supplies where they have been detected. Dyfonate is commonly applied to the soil as an insecticide for the control of variety of insects. However, critical information on the transformation of dyfonate into its hydrolytic byproducts during water treatment is lacking, even though they have been used in the field for a long time. In this study, dyfonate hydrolysis at elevated pH levels, simulating a water treatment operation or similar process, was investigated. Dyfonate, an organophosphorus insecticide used to treat infestations primarily on corn, was investigated due to its greater rate of hydrolysis observed during our screening studies. The hydrolysis of dyfonate was investigated at pH 10, 11, and 12 in phosphate buffered water over the course of 7 days. Two hydrolysis products, thiophenol and phenyl disulfide, were detected. Dyfonate and thiophenol were analysed using high pressure liquid chromatography/UV detection (HPLC/UV), while phenyl disulfide was detected using gas chromatography/mass spectrometry (GC/MS). The relative concentration profiles of dyfonate and its hydrolysis products, as well as their transformation pathways, were also reported. The data from this study will help environmental researchers understanding the hydrolytic pathways of dyfonate and its metabolites at different pHs in a water treatment system.     

Infrared structural studies of GeySe1−y glasses

Bulk and thin-film specimens of Ge_ySe_1?y have been made the range 0 < y < 0.50. Transmission and reflectivity measurements at 77 and 300 K are reported in the range 50–400 cm^?1. Mode assignment are made and an analysis is presented which supports the chain crossing model for y<0.33. The origin of several small spectral features is discussed in terms of crystal-like stacking within a volume of characterization dimension 10–20 Å.