Contribution to DEMO reactor RH maintenance assessment

The scope of this paper is a preliminary assessment of the maintenance scheme in support of the European study for the next generation of fusion reactor: DEMO. Despite other fusion machine requiring remote handling maintenance operations, DEMO is supposed to work under steady state operational conditions. Therefore, requirement on the maintenance scheme is stronger. To target a good availability of the machine along machine operation plan, it is necessary to draw an adequate maintenance scheme. Indeed, due to the high fluxes generated by the plasma in the vacuum vessel, the first wall lifetime is limited, so the frequent replacement is necessary. On current fusion experimental machine, as first wall load conditions are less severe, DEMO condition implies high level of requirement on maintenance time. During DEMO lifetime, several full first wall replacements are expected. To provide access to the vacuum vessel machine for first wall removal, preparatory work is required to set the machine to adequate maintenance conditions and to open the machine properly, the same situation at the end of the maintenance period. Shutdown duration for first wall replacement should be as short as possible to reach the availability target of the machine. From this statement, the maintenance duration should not exceed 20% of the total lifetime of the reactor operation. First wall segmentation (i.e. total number of component to replace) has a high impact onto the replacement time. Considering the number of feasible designs for the first wall segmentation, we concentrate remote handling concept assessments one type of segmentation, the one minimizing the numbers of modules to replace [4], [5], [6]. Assumption on Divertor segmentation for these DEMO studies have similarities with Divertor ITER design; therefore ITER design output is relevant [1], [2]. We assume divertor removal performed in shadow time, while removing the other first wall modules.     

Bench-Scale Testing of Nanofiltration for Seawater Desalination

A dual-staged nanofiltration process is being evaluated as an alternative to reverse osmosis for seawater desalination. The primary goal of this system is to reduce energy consumption while producing potable water at an acceptable recovery rate. Investigation of this system at the bench-scale level focused on membrane surface characterization, ion rejection (including boron, bromide, and iodide rejection), and flux decline. Results from this study showed that two commercially available nanofiltration membranes can effectively desalinate seawater. Although fouling was apparent—and resulted in approximately 20% flux decline over 3 days—a critical flux was not identifiable. Operation of the system at different cross-flow velocities revealed the significance of hydrodynamic conditions on the polarization modulus, and hence on membrane performance.     

Measurement of enzymatic activity and specificity of human and avian influenza neuraminidases from whole virus by glycoarray and MALDI-TOF mass spectrometry

Influenza neuraminidases hydrolyze the ketosidic linkage between N-acetylneuraminic acid and its adjacent galactose residue in sialosides. This enzyme is a tetrameric protein that plays a critical role in the release of progeny virions. Several methods have been described for the determination of neuraminidase activity, usually based on colorimetric, fluorescent, or chemiluminescent detection. However, only a few of these tests allow discrimination of the sialyl-linkage specificity (i.e., α2-3- versus α2-6-linked sialyllactosides) of the neuraminidase. Herein we report a glycoarray-based assay and a MALDI-TOF study for assessing the activity and specificity of two influenza neuraminidases on whole viruses. The human A(H3N2) and avian A(H5N2) neuraminidase activities were investigated. The results from both approaches demonstrated that α2-3 sialyllactoside was a better substrate than α2-6 sialyllactoside for both viruses and that H5N2 virus had a lower hydrolytic activity than H3N2.     

Gas sensors based on thick films of semi-conducting single walled carbon nanotubes

A comparative study was made of sorted semi-conducting single walled carbon nanotube (SWCNT) films and unsorted SWCNT films for gas sensing applications. The transmission line method is used to monitor separately the SWCNTs film resistance and the contact resistance between electrodes and the SWCNTs, thus revealing that the sensing mechanism mainly relies on a modification of the tube conductivity during gas exposure. The fabricated sensors demonstrate a detection limit of 20 ppb NO₂ and 600 ppb NH₃ mainly attributed to experimental setup limitations. Moreover, semi-conducting nanotubes happened to be 2.5 times more sensitive to NH₃ than unsorted ones, thus proving that selectivity can be improved by sorting the SWCNTs. The temperature dependence of the sensor sensitivity was studied, and a good agreement was found between experimental results and the Langmuir adsorption model.     

Bioactivity behaviour of biodegradable material comprising bioactive glass

Biocomposite of bioactive glass (BG) with chitosan polymer (CH) is prepared by freeze-drying technique. Obtained material is investigated by using several physico-chemical methods. The XRD and FTIR show the interface bonding interactions between glass and polymer. The specific surface and porosity of biocomposite were determined. In vitro assays were employed to evaluate the effect of chitosan addition on the glass by studying the chemical reactivity and bioactivity of the BG and BG/CH biocomposite after soaking in a simulated body fluid (SBF). The obtained results show the formation of a bioactive hydroxycarbonate apatite (HCA) layer and highlight the bioactivity and the kinetics of chemical reactivity of bioactive glass, particularly after association with chitosan. The BG/CH biocomposite has excellent ability to form an apatite layer. Inductively coupled plasma-optical emission spectrometry (ICP-OES) highlights the negative effect of chitosan on the silicon release toward the SBF of bioactive glass when in vitro assays.     

CuII Pyrazolyl-Benzimidazole Dinuclear Complexes with Remarkable Antioxidant Activity

Three dinuclear coordination complexes generated from 1-n-butyl-2-((5-methyl-1H-pyrazole-3-yl)methyl)-1H-benzimidazole ( L ), have been synthesized and characterized spectroscopically and structurally by single crystal X-ray diffraction analysis. Reaction with iron(II) chloride and then copper(II) nitrate led to a co-crystal containing 78 % of [Cu(NO₃)(μ-Cl)( L’ )]₂ ( C₁ ) and 22 % of [Cu(NO₃)(μ-NO₃)( L’ )]₂ ( C₂ ), where L was oxidized to a new ligand L^’ . A mechanism is provided. Reaction with copper chloride led to the dinuclear complex [Cu(Cl)(μ-Cl)( L) ]₂ ( C₃ ). The presence of N−H⋅⋅⋅O and C−H⋅⋅⋅O intermolecular interactions in the crystal structure of C₁ and C₂ , and C−H⋅⋅⋅N and C−H⋅⋅⋅Cl hydrogen bonding in the crystal structure of C₃ led to supramolecular structures that were confirmed by Hirshfeld surface analysis. The ligands and their complexes were tested for free radical scavenging activity and ferric reducing antioxidant power. The complex C₁ / C₂ shows remarkable antioxidant activities as compared to the ligand L and reference compounds.     

Design and Synthesis of Galactosylated Bifurcated Ligands with Nanomolar Affinity for Lectin LecA from Pseudomonas aeruginosa

Lectin A (LecA) from Pseudomonas aeruginosa is an established virulence factor. Glycoclusters that target LecA and are able to compete with human glycoconjugates present on epithelial cells are promising candidates to treat P. aeruginosa infection. A family of 32 glycodendrimers of generation 0 and 1 based on a bifurcated bis‐galactoside motif have been designed to interact with LecA. The influences both of the central multivalent core and of the aglycon of these glycodendrimers on their affinity toward LecA have been evaluated by use of a microarray technique, both qualitatively for rapid screening of the binding properties and also quantitatively (K_d). This has led to high‐affinity LecA ligands with K_d values in the low nanomolar range (K_d=22 nm for the best one).