Investigation of advanced materials for fusion alpha particle diagnostics

Fusion alpha particle diagnostics for ITER remain a challenging task. Standard escaping alpha particle detectors in present tokamaks are not applicable to ITER and techniques suitable for fusion reactor conditions need further research and development [1], [2]. The activation technique is widely used for the characterization of high fluence rates inside neutron reactors. Tokamak applications of the neutron activation technique are already well developed [3] whereas measuring escaping ions using this technique is a novel fusion plasma diagnostic development. Despite low alpha particle fluence levels in present tokamaks, promising results using activation technique combined with ultra-low level gamma-ray spectrometry [4] were achieved before in JET [5], [6].In this research work, we use new advanced detector materials. The material properties beneficial for alpha induced activation are (i) moderate neutron cross-sections (ii) ultra-high purity which reduces neutron-induced background activation and (iii) isotopic tailoring which increases the activation yield of the measured activation product.Two samples were obtained from GERDA[7], an experiment aimed at measuring the neutrinoless double beta decay in ⁷⁶Ge. These samples, made of highly pure (9 N) germanium highly enriched to 87% in isotope Ge-76, were irradiated in real D–D fusion plasma conditions inside the TEXTOR tokamak. Comparison of the calculated and the experimentally measured activity shows good agreement. Compared to previously investigated high temperature ceramic material [8], this candidate detector offers better prospects for signal to background S/B ratio, energy resolution and particle selectivity due to a unique alpha particle signature. Applicability to ITER is discussed. Finally, research needs for further development of this diagnostic technique are outlined.     

Machine loading and part type selection in flexible manufacturing systems

This paper presents a new approach to the loading problem in flexible manufacturing systems. It focuses on the existence of alternatives routes for each part type. Also, the optimal number of copies of each tool type to be loaded into each tool magazine is directly determined. Thus, the decision variables are the routing mix and the tool allocation. The loading objective is to balance machine workloads. Constraints on the number of available tools and on tool magazine capacities can be imposed. The problem is modelled as a mixed-integer linear program. Also, an extension of the model is formulated that includes part type selection.     

A system dynamics model for the supply chain procurement transport problem: comparing spreadsheets,fuzzy programming and simulation approaches

This article proposes a simulation approach based on system dynamics for operational procurement and transport planning in a two-level, multi-product and multi-period supply chain. This work uses the Vensim^® simulation tool to highlight the potential of system dynamics for supply chain simulation. A real continuous simulation application is presented in an automobile supply chain. The effectiveness of the proposed model is validated through the comparison of the results provided by spreadsheet-based simulation, fuzzy multi-objective programming and system dynamics-based simulation models. The fundamental point of this paper is that the simulation model is the most effective approach in quantifying the trade-off between number of truck shipments and average inventory level. In this case, the number of truck shipments is to be minimised, resulting in a higher inventory level. If the average inventory level were minimised, then there would be more truck shipments. Here, it is shown the benefit of this type of simulation model in reducing inventory by about 10%.     

Experimental Determination of Densities and Isobaric Vapor–Liquid Equilibria of Methyl Acetate and Ethyl Acetate with Alcohols (C3 and C4) at 0.3 MPa

The densities and excess volumes were determined at 298.15 K for the methyl acetate + 1-propanol, methyl acetate + 1-butanol, and ethyl acetate + 1-butanol mixtures. The vapor–liquid equilibria data at 0.3 MPa for these binary systems were obtained using a stainless steel equilibrium still. The activity coefficients were obtained from the experimental data using the Hayden and O’Connell method and the Yen and Woods equation. The binary systems in this study showed positive deviations from ideality. The experimental VLE data were verified with the point-to-point test of van Ness using the Barker routine and the Fredenslund criterion. The different versions of the UNIFAC and the ASOG group contribution models were applied.     

Estimation of the Thermodynamic Limit of Overheating for Bulk Water from Interfacial Properties

The limit of overheating or expanding is an important property of liquids, which is relevant for the design and safety assessment of processes involving pressurized liquids. In this work, the thermodynamic stability limit—the so-called spinodal—of water is calculated by molecular dynamics computer simulation, using the molecular potential model of Baranyai and Kiss. The spinodal pressure is obtained from the maximal tangential pressure within a liquid–vapor interface layer. The results are compared to predictions of various equations of state. Based on these comparisons, a set of equations of state is identified which gives reliable results in the metastable (overheated or expanded) liquid region of water down to $-55$  MPa.     

Determination of the Emissivity of Wood for Inspection by Infrared Thermography

Infrared thermography (IRT) is a non-contact technique for visualizing the surface temperature of objects based on the radiation emitted. Recently, this non-destructive technique (NDT) has begun to be used for the diagnosis and evaluation of wood structures. In the process of transforming radiant energy into temperature, which is performed by thermographic devices, one of the most significant properties that affects the calculation of temperature is the emissivity of the material being analyzed. Prior knowledge of the emissivity is essential for a thermographic inspection because it quantitatively determines the amount of energy that is actually produced by the material. In this research study, the emissivity of different types of wood has been determined, and the influences of temperature and surface finish of the samples on the emissivity values have been analyzed.     

Fiber‐particle morphological transition and its effect on impact strength of PS/HDPE blends

A morphological analysis was performed to study the effect of postextrusion conditions on the properties of polystyrene (PS)/high‐density polyethylene (HDPE) blends. The results show that both draw ratio (DR) and water contact distance (X) have a definite influence on the morphology and mean failure energy (MFE) of 3, 6, and 9% PS in HDPE. In general, the MFE of the blends increases with DR up to a critical value, being function of the water contact distance, where substantial decreases are observed. It was found that deformation of the dispersed phase increases with DR, but decreases with water contact distance. However, morphological analysis of the dispersed phase shows that particle–fiber transition occurs at critical values of DR and X up to a point where fiber break‐up occurs. These morphological transitions can easily explain the impact strength behavior of the samples. Using normalized data, a master curve is proposed relating the postextrusion conditions to the MFE. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Development of an intermediate moisture food from bean (Phaseolus vulgaris L.)

Beans consumption has been associated to reduction on chronic, non transmissible, diseases development. Generally, its consumption is less to the recommended and it is done principally as whole grain dishes. To increase the consumption, there is an especial interest in the use of new products. The main goal of this research was to design intermediate moisture bean purees (IMP) using soaked, cooked and grained Tortola bean, removing an important testa portion. In preparation of IMP two moisture levels, 25 and 30%, and two glycerol levels, 10 and 15%, were studied. Purees were preserved at ambient temperature (20 +/- 2 degrees C) for 30 days. Proximal analysis, phytate content and trypsin inhibitors were determined in the original non processed purees. IMPs were analyzed at preparation time and after 15 and 30 days of storage for moisture content, pH and water activity. Besides, microbiological analysis for total plate count on aerobic mesophile microorganisms, molds and yeast, total colifoms, fecal coliforms and Staphylococcus aureus, was carried out. Global quality and sensory acceptance was also determined. IMPs presented a(w) values between 0.800 and 0.844, a pH between 6.20 and 6.24 and the microbiological counting was negative or far below the accepted limits for more strict foods. IMPs presented good qualifications for global quality and were well accepted. Sensory parameters maintain their values during storage, except for color that in treatment with 30% moisture and 10% glycerol showed a light darkening. It is possible to elaborate intermediate moisture bean puree, with low level of antinutritional compounds, good quality and sensory acceptance and with adverse conditions for the development of food safety importance microorganisms.     

Capillary electrophoresis time-of-flight mass spectrometry for comparative metabolomics of transgenic versus conventional maize

In this work, capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) is proposed to identify and quantify the main metabolites in three lines of genetically modified (GM) maize and their corresponding nontransgenic parental lines grown under identical conditions. The shotgun-like approach for metabolomics developed in this work includes optimization of metabolite extraction from GM and non-GM maize, separation by CE, online electrospray-TOF-MS analysis, and data evaluation. A large number of extraction procedures and background electrolytes are tested in order to obtain a highly reproducible and informative metabolomic profile. Thus, using this approach, significant differences were systematically observed between the detected amounts of some metabolites in conventional varieties (Aristis, Tietar, and PR33P66 maize) compared with their corresponding transgenic lines (Aristis Bt, Tietar Bt, and PR33P66 Bt maize). Results point to some of these metabolites as possible biomarkers of transgenic Bt maize, although a larger number of samples needs to be analyzed in order to validate this point. It is concluded that metabolomics procedures based on CE-TOF-MS can open new perspectives in the study of transgenic organisms in order to corroborate (or not) their substantial equivalence with their conventional counterparts.     

Separation of single-walled carbon nanotubes by use of ionic liquid-aided capillary electrophoresis

This paper presents a simple, highly efficient method for analyzing single-walled carbon nanotube (SWNT) bundles based on (1) ultrasound-assisted solubilization/dispersion of SWNTs in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, (2) encapsulation of the nanotubes in sodium dodecyl sulfate micelles, and (3) analysis by capillary electrophoresis. The process by which SWNTs disperse in the ionic liquid was studied by Raman spectroscopy. No degradation of SWNTs was observed under mild sonication conditions. The shape and position changes observed in the Raman spectral bands for the nanotubes are ascribed to debundling and interaction with the ionic liquid. Separation of solubilized SWNTs was accomplished by using a 50 mM formic acid solution at pH 2.0 as background electrolyte and a potential of -10 kV. Under these conditions, separation was completed within only 4 min. Eighteen peaks for SWNTs were identified in the analysis of commercial SWNT bundles. The two types of bundles studied exhibited distinct, highly characteristic electrophoretic profiles which could be used to control SWNTs purity.