The first dairy product exclusively fermented by Propionibacterium freudenreichii: A new vector to study probiotic potentialities in vivo

Dairy propionibacteria display probiotic properties which require high populations of live and metabolically active propionibacteria in the colon. In this context, the probiotic vector determines probiotic efficiency. Fermented dairy products protect propionibacteria against digestive stresses and generally contain a complex mixture of lactic and propionic acid bacteria. This does not allow the identification of dairy propionibacteria specific beneficial effects. The aim of this study was to develop a dairy product exclusively fermented by dairy propionibacteria. As they grow poorly in milk, we determined their nutritional requirements concerning carbon and nitrogen by supplementing milk ultrafiltrate (UF) with different concentrations of lactate and casein hydrolysate. Milk or UF supplemented with 50 mM lactate and 5 g L⁻¹ casein hydrolysate allowed growth of all dairy propionibacteria studied. In these new fermented dairy products, dairy propionibacteria remained viable and stress-tolerant in vitro during minimum 15 days at 4 °C. The efficiency of milk fermented by the most tolerant Propionibacterium freudenreichii strain was evaluated in piglets. Viability and SCFA content in the colon evidenced survival and metabolic activity of P. freudenreichii. This work results in the design of a new food grade vector, which will allow preclinical and clinical trials.     

Kinetic Study of Hydroperoxide Degradation in Edible Oils Using Electron Spin Resonance Spectroscopy

Lipid oxidation is a complex phenomenon involving free radicals which are highly reactive molecular species. The life-time of these radical species is extremely short and their detection is therefore difficult. Several electron spin resonance (ESR) spectroscopy methodologies make it possible to identify, quantify and measure the reactivity of radical species formed during oxidation–reduction reactions. In this study we took advantage of the specificity of ESR spectroscopy to detect radical compounds in order to determine the rate constants of hydroperoxide degradation, a key reaction involved in lipid oxidation. The interaction of 5-doxyl stearic acid and lipid-derived radicals was studied by following the intensity of ESR spectra. A kinetic model was developed to simulate data analysis obtained by ESR and values of rate constants for hydroperoxide degradation were determined at 100 and 110 °C. This quantitative approach of ESR spectroscopy has produced useful information about new rate estimates for hydroperoxide degradation in edible oils.     

Fabrication and characterization of minor actinides bearing fuels obtained by conventional powder metallurgy process

The CEA is currently assessing minor actinides (MA) recycling in nuclear fuels in fast neutrons reactors (FNR). Two routes are investigated: homogeneous recycling, where MA are added up to several percents in UPu-type fuel to be used in the whole core, and heterogeneous recycling, which consists in higher amounts of MA in uranium oxide fuel used in the periphery of the core. The studies include various subject areas: neutronics, thermo-physical properties, coolant type (sodium, lead, bismuth, helium), etc…, and experimental work concerning the fabrication of minor actinides compounds.The first part of this work consisted in the structural study by XRD of AmO₂. We studied the lattice parameter change versus time due to α self-irradiation. In this context, AmO₂ powder was prepared in the ATALANTE facility in the CEA Marcoule. It is a first approach of swelling phenomenon at the structural scale which has been extended at the macroscopic scale in the second part of the work with the study of the geometrical stability in time of UO₂ sintered pellets containing 30% Am. Pellets were fabricated by conventional powder metallurgy process in hot cell at the laboratory scale. Swelling behaviour has been studied by accurate diameter measurements performed along the pellets and correlated to the cumulative α decay dose. Up to 2.1 × 10¹⁷ α decay in the sample, no evidence of pellet macroscopic swelling was observed.     

Influence of lignin's pH on polyurethane flexible foam formation and how to control it

Low pH of commercial lignins has a catastrophic impact on the polyurethane foaming reactions. Experiments were performed with 10 wt% of lignin with various pHs in polyols. Virgin lignin (pH 2.5, 35% moisture) has the most negative impact as it reduces the initial foam rising rate by 85% and the foam's final height by 35% as compared to the reference foam, lignin free. Drying of this lignin at 80°C for 12 h can reduce this impact while alkaline treatment to bring the lignin's pH to 6.6 almost cancel it. As revealed by in situ dielectric constant measurements, both reactions, gelling via polymerization and blowing via CO₂ degassing, are impacted. In situ Fourier transform infrared analysis of the foaming process demonstrated that blowing reaction is the most pH sensitive. Two methods to counter the pH influence by pH modification were tested and provide interesting results but also significant drawbacks limiting their applicability.     

Crosslinking of high‐density polyethylene in the presence of organic peroxides

The crosslinking efficiency of various commercially available organic peroxides (dicumyl peroxide, O,O‐t‐butyl O‐2‐ethylhexylperoxycarbonate, t‐butyl peroxybenzoate, t‐butyl 3,5,5‐trimethylperoxyhexanoate, and t‐butyl 2‐ethylperoxyhexanoate) was tested on high‐density polyethylene (HDPE) in its molten state. The variations of the concentrations of the peroxides versus the crosslinking extent were plotted for these peroxides, and the values were compared. Dicumyl peroxide was found to be the best crosslinking agent for HDPE. The efficiency of the HDPE crosslinking with each peroxy derivative was analyzed on the basis of the behavior of the radicals generated from it. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 75–81, 2004     

Functionalization and cross‐linking of high‐density polyethylene in the presence of dicumyl peroxide—An FTIR study

High‐density polyethylene was thermolysed with short‐chain organic compounds (additives) with an ester functional group in the presence of free radical initiator such as dicumyl peroxide at 160°C. The experimental results inferred that an additive with a hydrogen donor containing a thiol group showed better efficiency toward functionalization and an additive with a methylene bridged group showed better efficiency toward cross‐linking. The FTIR spectral results indicated that the area of the carbonyl peak at 1730 cm^?1 increased with the increase in percentage grafting of additives with simultaneous increase of cross‐linking. The ester grafting was further confirmed by saponification reaction. The possibility of acid functionalization via intramolecular hydrogen transfer was also checked through acid hydrolysis of the saponified products. A suitable reaction mechanism was proposed in order to explain the experimental and spectral data obtained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 766–774, 2005     

Servo piezo tool SPT400MML for the fast and precise machining of free forms

Recent requirements for accuracy and resolution demand higher quality in the machining of precision parts in many industries—such as optics, automotive and aerospace—by free form machining. The required operations are possible by using expensive manufacturing equipment in parallel with several processes such as grinding and polishing. By using a new fast tool servo, the so-called servo piezo tool SPT400MML, driven by a piezoelectric actuator for the precision diamond turning of non-symmetrical surfaces, components can be machined with a fast motion control of the tool (diamond or carbide). The SPT400MML embeds a patented amplified piezoelectric actuator APA400MML and a real-time controller based on a FPGA component able to improve the overall accuracy. Models based on mechanical FEM software and control design software are used to optimise the achieved performances. Experiments have been undertaken to show the capability to displace a diamond tool on a 400-µm stroke with a first resonant frequency of above 600 Hz.     

Using spectral and textural features from RapidEye images to estimate age and structural parameters of Cerrado vegetation

Cerrado is a savannah biome covering about 60% of the State of Minas Gerais, Brazil, but with a rate of conversion that surpasses that of all other biomes in Brazil. Remote sensing is the only practical means of monitoring the conversion and regeneration of this vegetation formation. The objective of this article is to model the process of regeneration of Cerrado vegetation and to estimate its age using a RapidEye image mosaic and textural features derived from the grey-level co-occurrence matrix. The study area is Parque Estadual Veredas do Peruaçu, a State Park in Minas Gerais, which was a plantation of eucalyptus until 1994 with a broad range of regeneration ages between 15 and 37 years. A total of 47 plots were surveyed for which the exact ages of regeneration are known and other structural variables were measured. Multiple regression and stepwise feature selection were used to create models that explain over 80% of the age, 58% of the crown closure, and 48% of the height of the vegetation. Texture proved essential for capturing the patterns of light and shadow generated by the trees of varying widths and heights.