Gelatin supports with immobilized laccase as sustainable biocatalysts for water treatment

Millimeter-size beads of gelatin are manufactured by dripping process to give enzyme supports qualified for micropollutants biodegradation in alternative wastewater treatment. The bead diameter is dependent on the tip diameter, the gelatin solution viscosity and the swelling of polymer chains in the collecting bath. Chemical crosslinking was performed with glutaraldehyde using optimal concentration to give mechanical and thermal properties suitable for application in stirred reactor in aqueous medium. Laccases from Trametes versicolor are grafted on the gelatin beads with glutaraldehyde. Sixty percentage of the initial enzymatic activity, evaluated by the oxidation of 2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is maintained after 10 successive cycles of reaction. Thermal stability at 60°C of immobilized biocatalysts is improved when compared to free enzymes (45% vs 10% of relative activity after 6 h of incubation). The simplicity of the procedure to form gelatin beads and their properties make them promising bio-based and biodegradable support for enzyme immobilization.     

Contribution of laser microdissection-based technology to proteomic analysis in hepatocellular carcinoma developing on cirrhosis

Hepatocellular carcinoma (HCC) is a major cause of cancer worldwide. Proteomic studies provide opportunities to uncover targets for the diagnosis and treatment of this disease. However, in HCC developing in a setting of cirrhosis, the detection of proteome alterations may be hampered by the increased cellular heterogeneity of tissue when analysing global liver homogenates. The aim of this study was to evaluate whether the identification of proteome alterations in these HCC cases was improved when the differential protein profile between tumour and non-tumour areas of liver was determined using hepatocytes isolated by laser microdissection (LM). Differential profiles established with LM-hepatocytes and liver section homogenates using 2-DE and MS exhibited noticeable differences: 30% of the protein spots with deregulated expression in tumorous LM-samples did not display any modification in homogenates; conversely 15% of proteins altered in tumorous homogenates were not impaired in LM-hepatocytes. These alterations resulted from the presence in cirrhotic liver of fibrotic stroma which displayed a protein pattern different from that determined in LM-hepatocytes. In conclusion, our data demonstrate the interest of LM in distinguishing between fibrotic and hepatocyte proteome alterations and thus the benefit of LM to proteome studies of HCC developing in a context of cirrhosis.     

The Phagocytosis of Lacticaseibacillus casei and Its Immunomodulatory Properties on Human Monocyte-Derived Dendritic Cells Depend on the Expression of Lc-p75, a Bacterial Peptidoglycan Hydrolase

The human gut symbiont Lacticaseibacillus (L.) casei (previously Lactobacillus casei) is under intense research due to its wide range of immunomodulatory effects on the human host. Dendritic cells (DCs) are crucial players in the direct and indirect communication with lactobacilli in the gastrointestinal tract. Here, we demonstrate that human monocyte-derived DCs (moDCs) are able to engulf L. casei BL23, in which the intact bacterial cell wall and morphology have a key role. The absence of the bacterial cell-wall-degrading enzyme, Lc-p75, in L. casei cells causes remarkable morphological changes, which have important consequences in the phagocytosis of L. casei by moDCs. Our results showed that the Lc-p75 mutation induced defective internalization and impaired proinflammatory and T-cell-polarizing cytokine secretion by bacteria-exposed moDCs. The T helper (Th) 1 and Th17 cell activating capacity of moDCs induced by the mutant L. casei was consequently reduced. Moreover, inhibition of the phagocytosis of wild-type bacteria showed similar results. Taken together, these data suggested that formation of short bacterial chains helps to exert the potent immunomodulatory properties of L. casei BL23.     

Deposition of thick and 50% porous YpSZ layer by spraying nitrate solution in a low pressure plasma reactor

The deposition of Yttria partially Stabilized Zirconia (YpSZ) for Thermal Barrier Coating application (TBC) is a current topic of interest. The TBC must exhibit high thickness (100–300 μm), vertical cracks in order to be a strain tolerant layer, and high porosity to decrease the thermal conductivity. In this paper, a solution of nitrate salt is introduced into a low pressure plasma discharge (600 Pa, 80–220 W) to obtain YpSZ layers.Several analytical techniques were used to study the characteristics and the stability of the YpSZ layers obtained in the low pressure plasma reactor. Optical emission spectroscopy indicated that the oxidant chemistry in the plasma is responsible for the formation of the oxide and the elimination of the nitrates at low temperature (T < 300 °C on the layer). SEM, water porosimetry, thermal diffusivity and XRD analyses were performed to study the effect of the parameters (power of the plasma discharge, post-treatment, heat treatment) on the structure, the morphology and the stability of YpSZ coatings. For example, it was observed that YpSZ is 50% porous in all cases and that the nanostructures of the coating resist against high temperature conditions (1200 °C/5 h).     

Preparation and characterization of magnesium coating deposited by cold spraying

Magnesium (Mg) and its alloys have a great potential as structural materials due to their beneficial combination of high strength to weight ratio, high thermal conductivity and good machinability. However, few works about Mg coatings fabricated by cold spraying can be found in the literature. Thus, Mg coatings prepared at different main gas temperatures by cold spraying were investigated as well as their microstructure, phase structure, oxygen content and microhardness. The critical velocity of the particle was evaluated through numerical simulations. The particle deformation behavior and bonding mechanism were discussed. The result of the oxygen content measurement shows that the oxygen contents of coatings did not increase compared with that of the feedstock powder. The simulation results show that the critical velocity of Mg particles was in the range from 653 m/s to 677 m/s. The observation of the coating fracture morphology shows that the formation of the coating was due to the intensive plastic deformation and mechanical interlocking. The microhardness of the coating increased with the increase of the main gas temperature from 350 °C to 450 °C due to the decrease of the coating porosity.     

CEA and AREVA R&D on HTR fuel fabrication and presentation of the CAPRI experimental manufacturing line

In the framework of the French V/HTR fuel development and qualification program, the Commissariat à l’Energie Atomique (CEA) and AREVA are conducting R&D projects covering the mastering of UO₂ coated particle and fuel compact fabrication technology. To fulfill this task, a review of past knowledge, of existing technologies and a preliminary laboratory-scale work program have been conducted with the aim of retrieving the know-how on HTR coated particle and compact manufacture:

• The different stages of UO₂ kernel fabrication GSP process have been reviewed, reproduced and improved.

• The experimental conditions for the chemical vapor deposition of coatings have been defined on dummy kernels and development of innovative characterization methods has been carried out.

• Former CERCA compacting process has been reviewed and updated.

In parallel, an experimental manufacturing line for coated particles, named GAIA, and a compacting line based on former CERCA compacting experience have been designed, constructed and are in operation since early 2005 at CEA Cadarache and CERCA Romans, respectively. These two facilities constitute the CAPRI line (CEA and AREVA PRoduction Integrated line).The major objectives of the CAPRI line are:

• to recover and validate past knowledge,

• to produce representative HTR TRISO fuel meeting industrial standards,

• to permit the optimization of reference fabrication processes for kernels and coatings defined previously at a laboratory-scale and the investigation of alternative and innovative fuel design (UCO kernel, ZrC coating),

• to test alternative compact process options and

• to fabricate and characterize fuel required for irradiation and qualification purpose.

This paper presents the status of progress of R&D conducted on HTR fuel particles and compact manufacture by early 2005 and the potential of the laboratory-scale HTR fuel CAPRI line.     

Self-assembling of atomic vacancies at an oxide/intermetallic alloy interface

Oxide layers grown on the surface provide an effective way of protecting metallic materials against corrosion for sustainable use in a broad range of applications. However, the growth of cavities at the metal/oxide interface weakens the adherence of the protective layer and can promote its spallation under service conditions, as observed for alumina layers formed by selective oxidation of aluminide intermetallic alloys used in high-temperature applications. Here we show that direct atomic-scale observations of the interface between an ultrathin protective oxide layer (alumina) grown on an intermetallic titanium aluminide substrate (TiAl) can be performed with techniques sensitive to the topmost atomic layers at the surface. Nanocavities resulting from the self-assembling of atomic vacancies injected at the interface by the growth mechanism of the protective oxide are observed for the first time, bringing new insight into the understanding of the fate of injected cavities in oxidation processes.     

Determinization of Transducers over Infinite Words: The General Case

We consider transducers over infinite words with a Büchi or a Muller acceptance condition. We give characterizations of functions that can be realized by Büchi and Muller sequential transducers. We describe an algorithm to determinize transducers defining functions over infinite words.     

Influence of Substrate Properties on the Formation of Suspension Plasma Sprayed Coatings

In this study, YSZ coatings were deposited on different substrate materials (stainless steel and aluminum) using suspension plasma spray technique. The effects of substrate properties (material, surface topology, temperature, and thickness) on the formation of coatings were investigated. The results showed that, with the identical spray parameters, the porosity is higher for the coatings deposited on aluminum than that on stainless steel due to the high thermal transfer ability of the former substrate material. The SEM results revealed that the microstructure of as-prepared coatings could be tailored from the vertical cracked structure to the columnar structure by increasing the substrate surface roughness and their formation mechanisms were discussed. The substrate preheating temperature has an influence on the microstructure of the coatings, especially in the interfacial region. Increasing the substrate temperature is an effective means for reducing the interface defects and for improving the adhesion of the coatings. With the increase in the substrate thickness, the quantity of the vertical cracks in the coatings is reduced and their width becomes narrower.     

Comparison between SiNx:H and hydrogen passivation of electromagnetically casted multicrystalline silicon material

This work intends to compare two different passivation methods for electromagnetically continuous pulling silicon (EMCP): remote plasma hydrogenation and remote plasma enhanced CVD of SiN followed by high-temperature sintering. All experiments are carried out on textured and non-textured EMCP samples from the same ingot. To check the effect of high-temperature diffusion on EMCP, a n⁺-emitter is formed on one group of the samples using POCl₃ diffusion. Passivation capabilities of both techniques are checked using measurements of minority carrier lifetime by means of microwave photoconductance decay mapping. Solar cells are made to compare lifetime measurement with cell parameters.