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Abstract  

Samples of the composition of 10Fe2O3·10CaO·80SiO2 were prepared by the sol-gel method and heat-treated in different atmospheres. They were investigated by X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. In the heat-treated samples in air iron is present up to 1000 °C in form of hematite and as Fe3+ in the tetrahedral sites. A wide range of hematite particle sizes was observed, the average size increased with heating temperature. At 1000 °C wollastonite was observed, at 1200 °C tridymite was formed and all the iron was incorporated in hematite. A heat-treatment at 500 °C under reducing conditions led to poorly crystallized maghemite and at 700 °C to metallic iron and fayalite formation.

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Summary  

The molecular structure and some properties of Be @Cn (n = 20, 60, 70, 80) endohedral metallofullerenes were analyzed using the HyperChem 7.0. Computational Chemistry Model Building Program. The results were in agreement with previous calculations using the ab initio method based on an all-electron mixed-basis approach within the framework of the local-density approximation. In the case of 7Be, the ion is inside the fullerene cage and tries to make an electronic connection with a six-membered ring of the fullerene cage in order to improve its atomic orbital distribution in the valence layer. Due to the ion radius value of only 0.45 Å and electronic capture decay, 7Be appears to emerge as an ideal tool for studying radionuclide half-life variation in different hosts.

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to the Monsanto catalyst [Rh(CO) 2 I 2 ] − , the complex accelerates the oxidative addition step by ca 300 times but inhibits the CO insertion step [ 19 ]. The reactivity of rhodium(I)-β-diketonato complexes is influenced by the electronic state of

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indicates an increase of the interlayer space upon displacement of DMSO and insertion of the ionic liquid. The increase of the interlayer space depends on the nature of the IL as well as on the size. The d 001 of the interlayer space is 1.35, 1.53 and 1

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Identification of micro-scale calorimetric devices

Part VI. An approach by RC-representative model to improvements in TAM microcalorimeters

Journal of Thermal Analysis and Calorimetry
Authors: R. Kirchner, M. Rodriguez de Rivera, J. Seidel, and V. Torra

Summary  

Using an RC model, the behavior of a TAM high-performance calorimeter (Thermometric AB, Sweden) equipped with a flow-mixing insertion vessel using independent pumps for each reactant is studied. The model shows a reliable sensitivity behavior for mixtures realized inside the cell. The model behavior is compared with experimental measurements.</o:p>

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Abstract  

The TRIGA research reactor operated by the Nuclear Science Center (NSCR) for Texas A&M University has the capability of producing fast transient power pulses by pneumatic ejection of the transient control rod upward out of the core to a preset distance corresponding to the desired input reactivity. The NSCR has been recently relicensed to operate in this mode. An evaluation of linearity of radioactivation to reactivity insertion and integrated pulse energy is presented. Pulse/irradiation timing considerations have proven to be of paramount importance. Pulse shape variations have been shown to significantly effect specific activation, especially at low reactivity insertions. The design and construction of a rapid transfer system for pulsed irradiation activation analysis is discussed.

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Abstract

TG/DTG/DTA curves can be used to estimate alimentary fats quality and antioxidants insertion efficiency. Sunflower oil obtained from Carnia hybrid and pork lard were used as matrices for the non-isothermal measurements. The first stage of non-isothermal decomposition is mostly important for the characterization of the fats thermal stability. The corresponding onset temperature is a good value for the comparison of different fats thermal stability or for the effectiveness evaluation in case of antioxidant insertion. In this study, it can be seen a considerable improvement of the fats thermal stability by adding small amounts from a natural antioxidant liquid mixture (obtained by alcoholic maceration of equal amounts of seven plants, namely: milfoil, rosemary, marjoram, thyme, lovage, oregano, and basil). Chlorophylls removal from the plant extract using two different adsorbents was accompanied by a four time decrease of the antiradical activity (measured by the DPPH method) with Sephadex LH20 and seventeen times decrease when activated carbon was used.

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Abstract  

The cleanup of high-level defense nuclear waste at the Hanford Site presents many challenges. These include removing and disposing of components from buried active waste tanks to allow new equipment insertion or hazards mitigation. This paper discusses a unique automated system that provides for retrieval, high-pressure washing, inventory measurement, and containment for disposal. Key to the inventory measurement is a three-detector high-purity germanium high-performance gamma-spectroscopy system capable of recovering data at up to 90-percent saturation (200,000 counts/s). Data recovery is based on a unique embedded electronic pulser and special software to report the inventory. Each detector has different shielding specified through simulation using the Monte Carlo computer code for N-particle transport modeling. This shielding provides performance over a dynamic range of eight orders of magnitude. This paper covers system description, calibration issues, and operation.

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