New spherical PET design with fresnel aperture orientation

A new spherical PET using Fresnel aperture is being designed, and construction is in progress. In the new design, the original spherical geometry is modified to accommodate a more flexible gantry construction and data processing while preserving the focused geometry of the original design. The performance of this new Fresnel aperture-SPET (F-SPET) is expected to follow closely with that of the original S-PET design. An analysis of an F-SPET designed with nine modular layers, with each modular layer being four rings, was performed in terms of the counting statistics and solid angle and compared with the original S-PET as well as the conventional cylindrical PET. According to the simulation results, the sensitivity gain of the Fresnel aperture-SPET remains a factor of 2 over the equivalent cylindrical system and has nearly the same performance as the original S-PET, while offering a simpler means in construction and data handling for the image reconstruction.     

Remediation of CCA-C treated wood using chelating agents

This study evaluates the effects of the common chelating agents, ethylenediaminetetracetic acid (EDTA), nitrilotriacetic acid (NTA), and oxalic acid (OA) on the removal of copper, chromium, and arsenic from CCA-C treated wood. In the study, the removal of the metal oxides from treated chips and sawdust by EDTA and NTA in conjunction with OA in dual extraction processes was investigated using batch-leaching experiments. Exposing CCA-C treated chips and sawdust to chelat extraction enhanced the removal of CCA-C components compared to extraction by deionized water. Grinding CCA-C treated wood chips into 40-mesh sawdust provided greater access to and removal of CCA-C components. Extraction with EDTA/OA and NTA/OA in dual extraction processes removed about 100% copper and arsenic and 90% chromium from CCA-C treated sawdust. However dual extraction of CCA-C treated chips resulted in about 80% copper and arsenic, and 70% chromium removal. In single extraction processes, EDTA and NTA removed significant amounts of copper from CCA-C treated chips and sawdust compared to other components.

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Entgiftung von CCA-C behandelte Holz mit Chelaten

Zusammenfassung Der Effekt von chelierenden Agenzien wird abgeschätzt. Zum Einsatz kamen Ethylendiamintetraacetat (EDTA), Nitriloessigsäure (NTA) und Oxalsäure (OA) zum Entfernen von Kupfer, Chrom und Arsen aus CCA-C-behandelten Spänen und Sägemehl. Untersucht wurde das Entfernen der Metalloxide mit EDTA und NTA in Kombination mit Oxalsäure in einer zweifachen Extraktion im Batchverfahren. Der Zusatz von Chelaten zu CCA-C-behandelten Spänen und Sägemehl verbessert die Entfernung von CCA-C-Komponenten im Vergleich zur Extraktion mit deionisiertem Wasser. Die Doppelte Extraktion entfernte Kupfer zu 100% und Chrom zu 90% aus CCA-C-benadeltem Sägemehl. Dagenen wurden aus Spänen nur 80% Kupfer und 70% Chrom entfernt. Auch die einfache Extraktion entfernt bereits beträchtliche Mengen an Kupfer im Vergleich zu den anderen Komponenten aus dem behandelten Holz.

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The authors acknowledge the support of Toktas Wood Impregnation Inc. and Unipole Forest Product Trading Ltd., a private Finnish-Turkish Joint Venture Corporation, Adana, TurkeyThe use of trade or firm names in this publication is for reader information only and does not imply endorsement by Forestry Faculty, Istanbul University of any product or service.     

Unit helium requirements for superconductive energy applications in the USA

Estimates of the helium requirements for superconductive magnetic energy storage, magnetically confined fusion reactors, superconducting power transmission lines, magnetohydrodynamic units, superconducting motors and generators, and particle accelerators are presented. The approach entails surveying estimates from system studies, then developing simple scaling laws to calculate helium inventories. Helium loss rates are discussed and applied to estimate annual helium makeup.     

Removal of phosphate from aqueous solutions by electro-coagulation

The aim of this paper was to investigate the feasibility of the removal of phosphate from aqueous solution by electro-coagulation (EC). The current density (CD) between 2.5 and 10 mA cm(-2) and duration in the limits of 5-20 min were tried for different concentrations. In order to determine optimal operating conditions, the EC process used for the phosphate removal was examined in dependence with the CD, initial concentrations and time. The results of the experimental batch processing showed high effectiveness of the EC method in removing phosphate from aqueous solutions.     

Spray drying of the mountain tea (Sideritis stricta) water extract by using different hydrocolloid carriers

The water extract of the mountain tea was spray-dried by using different food hydrocolloids viz. β-cyclodextrin (BCD), arabic gum (AG), and maltodextrins (MD19 and MD12) as carrier materials. Powdered samples were then subjected to product yield, moisture content, water activity, bulk density, solubility, color (Lab) and SEM particle microstructure analyses. Furthermore, color (Lab), turbidity (NTU), total phenolic content (TPC), total antioxidant activity (TAA) and volatile compound (β-pinene) analyses were performed on the reconstituted mountain tea samples. The product yield increased with the addition of the carrier materials whereas decreased at higher drying temperatures. The inlet air temperature of 155 °C provided the better retention for β-pinene. Almost all physicochemical properties of the spray-dried mountain tea samples were significantly (P < 0.05) affected by the inlet air temperature, the type and concentration of the carrier materials.     

Computational Investigation of the Electronic and Thermoelectric Properties of Strained Bulk Mg2Si

The purpose of this work was to investigate, by numerical simulation, the effect of isotropic and anisotropic strain on the transport properties of Mg₂Si. Analysis of the effects of temperature and charge-carrier concentration on evolution of the energy gap and on the thermoelectric properties of strained Mg₂Si is also reported in this paper. Gap evolution is highly dependent on the type of strain applied to the structure. The Seebeck coefficient (S) and power factor (PF) are strongly modified; a gain of up to 40% can be obtained for S and up to 100% for PF under specific conditions of strain. In most cases the temperature corresponding to the maximum value of PF was found to shift downward under the effect of strain.     

Comparative study on multifunctional behaviour of rare earth manganites with micro and nano grain size

We have investigated electrical and magnetotransport properties of La_0.7Sr_0.3MnO₃ samples with grain size in micro to nanometric regime. The structural parameters obtained by Rietveld refinement of X-ray diffraction data revealed perovskite structure with orthorhombic (Pnma) and rhombohedral (R3C) symmetry for nano and bulk samples respectively. The average particle size was 22 nm and 2 μm for the two representative samples. A metal–insulator transition and substantial increase in electrical resistivity was observed in nanomaterials. An enhanced magnetoresistance observed in nanomaterials samples, makes them more promising for advanced device applications. The magnetization study showed signature of ferromagnetic cluster behavior and higher temperature coefficient of magnetization in nanoparticle samples.