The Consumption of Food Products from Linseed-Fed Animals Maintains Erythrocyte Omega-3 Fatty Acids in Obese Humans

Based on mechanistic and epidemiological data, we raise the question of the relationship between qualitative dietary polyunsaturated fatty acids (PUFA) changes and increase in obesity. In this double-blind trial, we studied the effects on 160 overweight volunteers (body mass index, BMI >30) of a 90 days experimental diet rich principally in animal fat with a low PUFA/saturated fatty acid (SFA) ratio but a low n-6/n-3 ratio, using animal products obtained from linseed-fed animals. The control diet provided less animal fat, a higher PUFA/SFA ratio and a higher n-6/n-3 ratio. Both diets excluded seafood. In the experimental group, we observed a significant increase in red blood cell (RBC) α-linolenic acid content and a slight increase in EPA and DHA derivatives, while in the control group we observed a significant reduction in EPA and DHA content. Between groups now, the difference in the three n-3 fatty acids changes in RBC was significant. This demonstrates that plasma EPA and DHA levels can be maintained without fish if products from linseed-fed animals are used. During the diets, we noted a significant reduction in weight, BMI and hip circumference within both groups of volunteers. However, no significant difference was observed between the control group and the experimental group. Interestingly, 150 days after the end of the trial (i.e., day 240), we noted a significant weight gain in the control group, whereas no significant weight gain was observed in the experimental group. This was also observed for the BMI and hip circumference. Moreover, significant differences in BMI (P < 0.05) and weight (P = 0.05) appeared between the two groups, showing in both cases a smaller increase in the experimental group. During the 90 days trial, we did not observe any differences between groups in terms of total cholesterol, HDL cholesterol, LDL cholesterol or triglycerides, suggesting that the saturate content and the P/S ratio are not as important as the n-6 and n-3 fatty acid composition.     

ENERGY DISSIPATION DISTRIBUTION AND MIXING IN A TORUS REACTOR

Previous works devoted to the development of the swirl flow generated by rotation of the marine screw impeller in the loop toroidal reactor show that the flow structure is characterized by the existence of a secondary flow. The deformation of the axial velocity profile, due to the bends curvature and the rotation of the agitator, modify considerably the friction and the transfer near the wall. The objective of this work is to study the toroidal flow and to characterize the wall turbulence. The wall shear stress distribution in the torus were performed by using an electrochemical method. The measurements of the wall shear stress were carried out in the inner and outer walls. The evolution of the wall velocity gradient with the longitudinal distance depends on the location in the torus. These results allow to obtain information about the friction factor, which is compared with the one measured directly by using piezometric connections. The experimental determination of the axial dispersion coefficient is obtained by using the dispersion plug flow model with a total recirculation. Finally, a relationship between the turbulent characteristics and the mixing parameters has been established.     

Crazing,yielding, and fracture of polymers. I. Ductile brittle transition in polycarbonate

Most thermoplastics far below their glass transition give a brittle fracture when de-formed in uniaxial tension. Bisphenol-A polycarbonates are an exception and deform in a ductile manner. However, it has been observed in Izod impact studies of notched samples that the mode of failure changes from a ductile to a brittle fracture on annealing samples below T_g. It has been found that, when notched samples are stressed, a Griffith type flaw is formed under the notch. The criterion for the ductile brittle transition is evaluated in terms of σG (the stress required to propagate the Griffith flaw), and σ_y, the yield stress for the polymer. It has been found that the density and yield stress for the samples annealed at various temperatures are dependent upon previous thermal history and in particular on the molecular weíAght. On the basis of these measurements, it is concluded that many of the so-called anomalous effects observed with polycarbonate can be explained.     

Characterization of hydrogen production by Platymonas Subcordiformis in torus photobioreactor

Platymonas subcordiformis, a marine green alga, was demonstrated to photo-biologically produce hydrogen when regulated by a kind of proton uncoupler CCCP (Carbonyl Cyanide m-Chlorophenylhydrazone). In this paper, hydrogen production experiments by P. subcordiformis were carried out in a torus photobioreactor equipped with a mass spectrometer and other necessary sensors so that instantaneous gas components could be measured and other successive physiological states could be well recorded.     

Ciguatoxins and brevetoxins, neurotoxic polyether compounds active on sodium channels

Ciguatoxins (CTXs) and brevetoxins (PbTxs) modify the activation and inactivation processes of voltage-sensitive sodium channels (VSSC). In this study, the specific binding to rat brain synaptosomes of two commercial PbTxs, five purified CTXs and their derivatives was evaluated in competition with various concentrations of radiolabelled brevetoxin ([3H]PbTx-3). The results indicate that all CTXs bind specifically and with high affinity to sodium channels. Statistical analysis of the calculated inhibition constants identified two classes of toxins: the PbTxs and the less polar CTXs, and a group of CTXs of very high affinity. Relatively small chemical differences between the CTXs gave rise to significant differences in their affinity to the rat brain sodium channels. Cytotoxic effects associated with sodium channel activation were evaluated for the two classes of toxins on murine neuroblastoma cells, and their acute toxicity was determined in mice. CTXs have shown high affinities to VSSC of rat brain membranes and strong cytotoxic effects on neuroblastoma cells which correlate with their very low LD50 in mice. For PbTxs, it is different. Although binding with high affinity to VSSC and giving rise to significant cytotoxic effects, they are known to be poorly toxic intraperitoneally to mice. Furthermore, within the CTXs family, even though the most toxic compound (CTX-1B) has the highest affinity and the less toxic one (CTX-4B) the lowest affinity, a detailed analysis of the data pointed out a complex situation: (i) high affinity and toxicity seem to be related to the hydroxylation of the molecule on the A-ring rather than to the backbone type, (ii) acute toxicity in mice does not follow exactly the sodium-dependent cytotoxicity on neuroblastoma cells. These data suggest that the high toxicity of CTXs is related to sodium-dependent disturbances of the excitable membranes but might also involve other cellular mechanisms.     

Phase Diagram, Short-Range Structure, and Amorphous Phases in the ZrO2-GeO2(-H2O) System

Gels of the ZrO₂-GeO₂(-H₂O) system have been prepared via the hydrolysis-polycondensation of zirconium and germanium isopropoxides. Phase relationships have been deduced from differential thermal analysis, thermogravimetric analysis, and shrinkage analysis and are discussed on the basis of X-ray diffractometry and Raman scattering studies. Emphasis has been given to understanding the short-range structure. A small glass-forming domain is observed in the temperature range of 600°−700°C for compositions of 30–40 mol% GeO₂.     

Mise en évidence expérimentale des interactions entre pâte interstitielle et granulats dans l’écoulement du béton frais vibré

L’étude du comportement mécanique du béton frais est abordée en considérant ce matériau très hétérogène comme un milieu diphasique, pate interstitielle-granulats. La caractérisation propre de chaque phase ne suffit pas pour décrire le comportement global du matériau. Les interactions entre granulats et pate interstitielle doivent être impérativement prises en considération; elles sont analysées à travers l’étude expérimentale d’un écoulement sous charge constante et sous vibrations dans un ajutage à axe vertical. Les granulats interviennent dans l’écoulement du béton frais vibré par des actions d’encombrement qui tendent à gêner l’écoulement mais aussi par des effets liés à leur masse volumique qui peuvent, en fonction de la différence de masse volumique pate-granulats, favoriser l’écoulement. Summary The study of the mechanical behaviour of fresh concrete is approached considering this very heterogeneous material as a diphasic medium (interstitial paste-aggregates). The specific characterization of each phase is not sufficient to describe the complete behaviour of the mix. The mutual actions of aggregates and interstitial paste must be imperatively taken into account; they are analysed with the aid of an experimental study of the flow through a vertical nozzle under constant load and vibrations. Aggregates appear in the fresh concrete flow through actions of hindrance reactions which impede the flow, but also through effects of gravity which can aid the flow in function of the difference of density between aggregates and interstitial paste.      

Study of Nicalon-based ceramic fibres and powders by EXAFS spectrometry,X-ray diffractometry and some additional methods

The Nicalon SiC-based ceramic fibres and their precursors have been investigated by complementary techniques: EXAFS, WAXS, ESCA and NMR. For SiC-Nicalon fibres, an alternative model is proposed based on a microcrystalline structure where pureβ-SiC is embedded in a continuum of tetrahedral SiC_xO_y(x+y=4). We have found that the inorganic material skeleton is already contained in the carbon and silicon structure of the polymer precursor.