Study of ITER equatorial port plug handling system and vacuum sealing interface

In the field of the ITER port plug engineering and integration task, CEA has contributed to define proposals concerning the port plugs vacuum sealing interface with the vessel flange and the equatorial plug handling.The 2001 baseline vacuum flange sealing consisted of TIG welding of a 316L strip plate on to U shapes. This arrangement presented some issues like welding access, implementation of tools, lip consumption, complex local leak test, continuous leak checking. Therefore, an alternate sealing solution based on the use of metallic gaskets is proposed. The different technical aspects are discussed to explain how this design can simplify the maintenance and deal with safety and vacuum requirements.The design of the mechanical attachment and vacuum sealing of the plug has constantly evolved, but the associated remote handling equipment was not systematically reviewed. An update of the cask and maintenance procedure was studied in order to design it in accordance with the last generic plug flange design. This includes a concept of a gripping system that uses the plug flange bolting area and, to help the remote handling process, a cantilever assisting system is suggested to increase the reliability of the transfer operation between vacuum vessel and cask.     

Status of ITER dimensional tolerance studies

The optimization of the manufacturing/assembly tolerances and processes in ITER Experimental Nuclear Fusion Device is one of the key tasks to optimize the fabrication cost, to prevent problems during assembly and to ensure that the critical homogeneity of the magnetic field and the positioning requirements of the plasma facing components can be achieved. This task is further complicated by the strong interplay among the various Tokamak systems, as for instance in the inner region of the machine where the clearances between Central Solenoid, Toroidal Field Coils, Thermal Shield, Vacuum Vessel and In-Vessel components have been minimized for their large influence on the magnetic flux and the overall machine cost.A 3D tolerance simulation analysis of ITER Tokamak machine has been developed based on 3DCS dedicated software. The dimensional variation model is representative of Tokamak functional tolerances and processes, predicting accurate values for the amount of variation on critical areas. In addition, dimensional simulations help to determine the key tolerances that contribute to a particular variation.This paper describes the current status of the Tokamak dimensional variation studies and its management plan, highlighting the status of compliance of allocated tolerances with input requirements. Management of risk issues and corrective actions are also described.     

Attentional load associated with performing and stabilizing preferred bimanual patterns.

This study aimed to determine whether the stability of preferred coordination patterns could be modified intentionally and whether such stabilization involved an additional attentional load. Eight participants performed in-phase and anti-phase bimanual coordination patterns, a reaction time (RT) task, and several dual tasks (coordination + RT) that manipulated attentional priority by requiring either shared attention, priority to the coordination task, or priority to the RT task. Results showed that RT was smaller for in-phase than anti-phase. Moreover, attentional manipulations led to a trade-off between pattern stability and RT performance. This suggests that performing and intentionally stabilizing a coordination pattern incur a central cost that depends on the coordination pattern's dynamic properties. Thus, this study opens a conceptual and methodological bridge between information processing and dynamic approaches to coordination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability of hydrogen incorporated in ZnO nanowires by plasma treatment

The stability of hydrogen in ZnO is studied using hydrogenated nanowires by plasma treatment. Enhanced near band edge UV emission and reduced defect level green emission is observed after hydrogen plasma treatment. Through thermal stability tests, this effect is found to be stable at room temperature and nearly stable up to ~500 K, but begins to deteriorate at higher temperature. The study of the irradiation stability of the hydrogen in ZnO nanowires shows that the hydrogen is stable under an electron beam with an accelerating voltage lower than 5 kV, but is not stable under 10 kV or under an intensive laser beam. The results could benefit the further understanding of the role of hydrogen in ZnO and light-emitting devices based on hydrogenated ZnO.     

Characterisation of the spoilage microbiota in raw salmon (Salmo salar) steaks stored under vacuum or modified atmosphere packaging combining conventional methods and PCR-TTGE

In order to characterise the spoilage related to microbiota of raw salmon, a combination of culture-dependent and -independent methods, including PCR–TTGE, was used to analyse 3 raw salmon batches stored for 3 days at chilled temperature in modified atmosphere packaging (MAP) (50% CO₂/50% N₂) or under vacuum. Sensory evaluation, microbiological enumeration and chemical analysis were performed after 3, 7 and 10 days of storage. At the onset of spoilage, 65 bacterial isolates were picked from the plates. Thus, 13 different genera or species were identified by phenotypic and molecular tests: Serratia spp., Photobacterium phosphoreum, Yersinia intermedia, Hafnia alvei, Buttiauxella gaviniae, Pseudomonas sp., Carnobacterium maltaromaticum, Carnobacterium divergens, Lactococcus piscium, Lactobacillus fuchuensis, Vagococcus carniphilus, Leuconostoc gasicomitatum and Brochothrix thermosphacta. The PCR–TTGE profiles and band identification enabled a shift of the dominant populations during the storage to be visualised for all the batches, probably due to the temperature change and the packaging. At the beginning of storage, Pseudomonas sp. dominated the raw salmon microbiota while in the following days (7 and 10), P. phosphoreum and L. piscium were identified as the main bacterial groups. This study enhances the knowledge of MAP and vacuum-packed raw salmon spoilage microbiota.     

Sensory and physicochemical evolution of tropical cooked peeled shrimp inoculated by Brochothrix thermosphacta and Lactococcus piscium CNCM I-4031 during storage at 8°C

This study investigated the sensory quality and physicochemical evolution (pH, glucose, l-lactic acid, biogenic amine, free amino-acids and volatile compounds) during storage at 8 °C of cooked peeled shrimp inoculated with the specific spoilage bacteria Brochothrix thermosphacta alone or mixed with the protective strain Lactococcus piscium CNCM I-4031. Growth of both bacteria was monitored at regular intervals during storage by microbial counts and the thermal temperature gradient gel electrophoresis (TTGE) technique. Bacterial counts showed that L. piscium and B. thermosphacta inoculated at 7 log CFU/g and 3 log CFU/g were well adapted to shrimp, reaching a maximum level of 9 log CFU/g after 4 days and 10 days respectively. In mixed culture, the growth of B. thermosphacta was reduced by 3.2 ± 0.1 log CFU/g. The TTGE technique allowed monitoring the colonisation of the strains on the shrimp matrix and confirming the dominance of L. piscium in mixed culture throughout the experiment. Sensory analysis confirmed that B. thermosphacta spoiled the product after 11 days, when its cell number attained 8 log CFU/g with the emission of strong butter/caramel off-odours. This sensory profile could be linked to the production of 2,3 butanedione, cyclopentanol, 3-methylbutanol, 3-methylbutanal, 2-methylbutanal, 4-methyl-3-chloro-3-pentanol and ethanol, which were produced in more significant quantities in the B. thermosphacta batch than in the batches in which the protective strain was present. On the contrary, TVBN and TMA were not suitable as quality indicators for B. thermosphacta spoilage activity. In the products where the protective L. piscium strain was present, no adverse effect on sensory quality was noted by the sensory panels. Moreover, biogenic amine assessment did not show any histamine or tyramine production by this strain, underlining its safety profile. Both strains produced lactic acid (1850 mg/kg in L. piscium and B. thermosphacta batch on days 3 and 10 respectively; 3830 mg/kg on day 7 in mixed culture) and the pH decrease from 6.6 ± 0.0 to 5.9 ± 0.1 was similar in all batches. Lactic acid production or competition for free amino-acid was not involved in the inhibition mechanism; however rapid glucose consumption by L. piscium could partially explain the growth limitation of the spoilage micro-organism. This study demonstrated the spoilage characteristic of B. thermosphacta and the usefulness of L. piscium as a bioprotective culture for tropical cooked peeled shrimp without any adverse effect on the sensory quality of the product.     

Experimental study of a mechanically ventilated double-skin façade with venetian sun-shading device: A full-scale investigation in controlled environment

The aim of this article is to present results of an experimental campaign performed on a full-scale facility provided with a double-skin façade. The behaviour of this architectural concept is tested under controlled climatic conditions. A summer case is scrutinised under different configurations: variation of the airflow through the double-skin façade and different angle of the solar shading device. This paper describes the experimental conditions, as well the test facility and the tested façade element. The results show the temperatures of the test cell and the façade and how they depend on the climatic conditions and the sun-shading device blade angles. One objective of this research was to measure and provide extensive data set detailing air and surface temperatures on the double-skin façade, together with airflow rates and air velocities. The experiments are fully described so that the results can be used for the validation of numerical models dealing with ventilated double-skin façades with venetian sun-shading device.     

Highly efficient electrocatalysts fabricated via electrophoretic deposition for alcohol oxidation,oxygen reduction,hydrogen evolution,and oxygen evolution reactions

Electrophoretic deposition (EPD) is a versatile technique that has drawn attention due to its ease of use and performance in depositing high-quality layers at room temperature. This technique principle is based on the deposition of charged particles from a stable colloidal suspension on a conductive substrate using either a direct or alternating current. Using relatively simple and low-cost equipment, the EPD technique enables the deposition of layers with controlled microstructures at nanoscale. The EPD technique has been particularly successful in the fabrication of the electrocatalyst layers for low-temperature fuel cells, which are anchored on the top of the fuel cell electrodes. In comparison with other electrocatalyst layer deposition techniques such as drop-casting, the EPD technique offers clear advantages for the control of the thickness and packing density of the electrocatalyst layers. Owing to the dense packing density, electrocatalyst layers deposited by EPD could achieve enhanced conductivity and efficiency. The present review aims at comprehensively evaluating the recently published results on the electrocatalyst layers fabricated by EPD and applied in oxygen reduction reactions, alcohol electro-oxidation reactions, hydrogen evolution reactions, and oxygen evolution reactions.