IGES Model Comparison System: A Tool for Tsting and Validating IGES Processors

The IGES Model Comparison System (IMCOS) is the first test tool to allow an easy and automatic semantic comparison of CAD models represented in IGES format. By systematically analyzing and comparing entity data and structures of generated and exchanged IGES models, it detects loss of information and functionality resulting from model exchange via IGES processors. IMCOS was designed and implemented as a tabledriven IGES processor to allow external control of the comparison process and full coverage of the current version of IGES (Version 3.0) and future versions. This article presents the basic concepts of IMCOS. The great interest in and discussion of IMCOS have shown the importance of such a test tool. IMCOS may be used as one of several test tools within an overall IGES verification program.     

Four-dimensional multiphoton microscopy with time-correlated single-photon counting

We report on the implementation of fluorescence-lifetime imaging in multiphoton excitation microscopy that uses PC-compatible modules for time-correlated single-photon counting. Four-dimensional data stacks are produced with each pixel featuring fluorescence-decay curves that consist of as many as 4096 bins. Fluorescence lifetime(s) and their amplitude(s) are extracted by statistical methods at each pixel or in arbitrarily defined regions of interest. When employing an avalanche photodiode the width of the temporal response function is 420 ps. Although this response confines the temporal resolution to values greater than several hundreds of picoseconds, the lifetime precision is determined by the signal-to-noise ratio and can be in the range of tens of picosconds. Lifetime changes are visualized in pulsed-laser-deposited fluorescent layers as well as in cyan fluorescent proteins that transfer energy to yellow fluorescent proteins in live mammalian cells.     

Discrimination between myocardial and skeletal muscle injury by assessment of the plasma ratio of myoglobin over fatty acid-binding protein

BACKGROUND: Myoglobin and fatty acid-binding protein (FABP) each are useful as early biochemical markers of muscle injury. We studied whether the ratio of myoglobin over FABP in plasma can be used to distinguish myocardial from skeletal muscle injury. METHODS AND RESULTS: Myoglobin and FABP were assayed immunochemically in tissue samples of human heart and skeletal muscle and in serial plasma samples from 22 patients with acute myocardial infarction (AMI), from 9 patients undergoing aortic surgery (causing injury of skeletal muscles), and from 10 patients undergoing cardiac surgery. In human heart tissue, the myoglobin/FABP ratio was 4.5 and in skeletal muscles varied from 21 to 73. After AMI, the plasma concentrations of both proteins were elevated between approximately 1 and 15 to 20 hours after the onset of symptoms. In this period, the myoglobin/FABP ratio was constant both in subgroups of patients receiving and those not receiving thrombolytics and amounted to 5.3 +/- 1.2 (SD). In serum from aortic surgery patients, both proteins were elevated between 6 and 24 hours after surgery; the myoglobin/FABP ratio was 45 +/- 22 (SD), which is significantly different from plasma values in AMI patients (P < .001). In patients with cardiac surgery, the ratio increased from 11.3 +/- 4.7 to 32.1 +/- 13.6 (SD) during 24 hours after surgery, indicating more rapid release of protein from injured myocardium than from skeletal muscles. CONCLUSIONS: The ratio of the concentrations of myoglobin over FABP in plasma from patients with muscle injury reflects the ratio found in the affected tissue. Since this ratio is different between heart (4.5) and skeletal muscle (20 to 70), its assessment in plasma allows the discrimination between myocardial and skeletal muscle injury in humans.     

Recent achievements in the development of partitioning processes of minor actinides from nuclear wastes obtained in the frame of the NEWPART European programme (1996–1999)

Partitioning of long-lived minor actinides (americium and curium) from the nuclear wastes issuing the reprocessing of nuclear spent fuels, in order to transmute them into short-lived nuclides or to condition them into stable crystalline matrices, was the subject of intense research within the NEWPART research program of the European 4^th Frame Work Program, FWP (1996–1999). The target waste considered was the acidic raffinate (HAR) issuing the reprocessing of the used nuclear fuels by the PUREX process. A two step separation process based on liquid-liquid extraction was designed. The first step consists in the co-separation of the mixture of trivalent actinides and lanthanides from the HAR by extraction with a malonamide extractant (DIAMEX process), while the second step concerns the actinides(III)/lanthanides(III) group separation (SANEX process). Several DIAMEX and SANEX processes were developed and successfully tested with cold, spiked and genuine high active effluents. The research carried out also included basic and fundamental works in order to better understand the relationships between the structures of the extractants and their affinities for the target metal ions. The lecture highlighted both the basic and applied aspects of the research. This work will be pursued (PARTNEW program) within the 5^th FWP of the European Union during the period 2000–2003.     

Separation of plutonium from lanthanum by electrolysis in LiCl–KCl onto molten bismuth electrode

This work presents a study on the electroseparation of plutonium from lanthanum using molten bismuth electrodes in LiCl–KCl eutectic at 733 K. The reduction potentials of Pu³⁺ and La³⁺ ions were measured on a Bi thin film electrode using cyclic voltammetry (CV). A difference between the peak potentials for the formation of PuBi₂ and LaBi₂ of approximately 100 mV was found. Separation tests were then carried out using different current densities and salt phase compositions between a plutonium rod anode and an unstirred molten Bi cathode in order to evaluate the efficiency of an electrolytic separation process. At a current density of 12 mA/cm²/wt% (Pu³⁺), only Pu³⁺ ions are reduced into the molten Bi electrode, leaving La³⁺ ions in the salt melt. Similar results were found at two different Pu/La concentration ratios ([Pu]/[La] = 4 and 10). At a current density of 26 mA/cm²/wt% (Pu³⁺), co-reduction of Pu and La was observed as expected by the large negative potential of the Bi cathode during the separation test.     

Biomodification of fats and oils: Trials withCandida lipolytica

Various oil-accumulating yeasts were tested for their ability to produce lipase and live on fats and oils as carbon sources. Of these,Candida lipolytica seemed most promising, and the possibility was explored of modifying fats and oils by fermenting them withC. lipolytica and extracting the modified oil deposited in the yeast cells. Oxygen was required for the growth of yeast on fats and oils, but unless the oxygen level was controlled at a low value after cell populations peaked, most of the substrate oil was converted to citrates rather than accumulating as oil. Oil accumulation byC. lipolytica from a corn oil substrate was slightly depressed by excess nitrogen in the medium. The yeasts were able to use about 18 g/l of oil in 72 hr. At substrate oil levels greater than 18 g/l, the dry yeasts were 60% oil, and about 45–57% of the substrate oil was recovered as yeast oil. The fatty acid composition of the yeast oil was quite similar to that of the substrate oil under optimum conditions of deposition. Sterols, but not tocopherols, were transferred from the substrate to the yeast oil.Candida lipolytica oil was high in free fatty acids. The greatest potential for biomodification by fermentation withC. lipolytica seems to be in altering glyceride structure. Journal Paper No. J-11337 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Project No. 2493.     

Extraction of Natural Substances with Supercritical Gases, 10. Communication: Qualitative and Quantitative Determination of Solubilities of Steroids in Supercritical Carbon Dioxide

The solubility of 35 steroids in supercritical carbon dioxide at 40°C was examined qualitatively and quantitatively for the pressure range between 80 and 200 bat. Relations between structure of the compound and its solubility were established and rules of thumb worked out which enable us to estimate the solubility of a steroid in an extraction with supercritical gases, based upon the number of hydroxyl and carboxyl groups of the steroid basic structure. In the most favourable case we obtained solubilities of sterols with approximately 1 mg/Nl at 200 bar. All compounds with more than three hydroxyl or carboxyl groups in the molecule, and the corresponding glycosides are insoluble.     

Electrochemical behaviour of americium ions in LiCl-KCl eutectic melt

This work presents a study on the electrochemical properties of AmCl₃ in a molten LiCl-KCl eutectic, at a temperature range of 733-833 K. Transient electrochemical techniques, such as cyclic voltammetry and chronopotentiometry, on inert metallic tungsten working electrode have been used to investigate the reduction mechanism of Am³⁺ ions. The results show that Am³⁺ is reduced to Am metal by a two-step mechanism corresponding to the Am³⁺/Am²⁺ and Am²⁺/Am⁰ transitions. Formal standard potentials of Am³⁺/Am²⁺ ( versus Cl₂/Cl⁻ at 733 K) and Am²⁺/Am⁰ ( versus Cl₂/Cl⁻ at 733 K) redox couples as well as diffusion coefficients of Am³⁺ and Am²⁺ (2.4 × 10⁻⁵ and 1.15 × 10⁻⁵ cm² s⁻¹ at 733 K, respectively) have been calculated at three different temperatures. In the studied range of temperature, the DAm3+/DAm2+ ratio was found to be around 2. In addition, thermodynamic properties have been calculated for Am³⁺ () and Am²⁺ () and compared to thermodynamic reference data in order to estimate activity coefficients (Am³⁺ = 4.7 × 10⁻³ and Am²⁺ = 2.7 × 10⁻² at 733 K) in the molten LiCl-KCl eutectic.