Parthenocissus tricuspidata: un modèle végétal d’adhésion biologique

The Parthenocissus Tricuspidata, genus of the Vitaceae family, is a rustic plant with lianas, whose tendrils tips have organelles called adhesive discs that, set near a substrate, adhere to it.Studies of A.G. ENDRESS, W. THOMSON, S. JUNKER attribue the disc adhesion ability to an adhesive substance secretion instead of a suction mechanism.Teeth were set beneath the tendrils and in few weeks the adhesion to enamel, dentin and radicular cement was so strong as the usual adhesion to the wall, except with teeth that were set before in fluoride gel, because of the element cytotoxicity.Then the adhesion place was investigated with microanalysis and S.E.M.The microanalysis has shown calcium and phosphorus both on enamel and on adhesion place, while silicon, sulphur, chlorine and potassium were only on the adherent vegetable substance.The S.E.M. analysis was conducted on the enamel surface, after removing of the vegetable, and perpendicularly to the adhesion surface of the vegetable with the enamel, the dentin and the cementum.La Parthenocissus Tricuspidata, genre appartenant à la famille des Ampélidiacées, est une plante rustique, grimpante, pourvue de vrilles à l’extrémité desquelles se différencient des organes appelés disques adhé ifs qui, au voisinage d’un substrat, adhèrent à celui-ci de façon tenace.Des études de A.G. ENDRESS, W. THOMSON, S. JUNKER n’attribuent pas tellement à ce disque la capacité d’adhérer au substrat avec un mécanisme à ventouse mais plutôt grâce à la sécrétion d’une substance adhésive.Les éléments dentaires ont été solidement fixés au-dessous des vrilles et au bout de quelques semaines l’adhésion sur l’émail, sur la dentine et sur le cément radiculaire se révèlait aussi tenace que l’adhésion qui se produit habituellement pour le cément, à l’exception des éléments immergés auparavant dans un gel fluoré, peut-être à cause de la cytotoxicité de l’élément lui-même.Le siège de l’adhésion à l’émail a été ensuite soumis à deux types d’examens: la microanalyse et la microscopie électronique à balayage.La microanalyse a révélé la présence de calcium et de phosphore aussi bien sur l’émail que sur la zone d’adhésion, alors que le silicium, le soufre, le chlore et le potassium ne se rencontrent que sur la substance végétale adhérée.L’étude au M.E.B. a été effectuée soit sur la surface de l’émail, après séparation du végétal, soit sur la coupe orthogonale à la surface d’adhésion du végétal à l’émail, à la dentine et au cément radiculaire

High-temperature and high-pressure behavior of carbonates in the ternary diagram CaCO3-MgCO3-FeCO3

We report the thermal expansion and the compressibility of carbonates in the ternary compositional diagram CaCO3-MgCO3-FeCO3, determined by in situ X-ray powder and single-crystal diffraction. High-temperature experiments were performed by high-resolution X-ray synchrotron powder diffraction from ambient to decarbonation temperatures (25-850 \ub0C). Single-crystal synchrotron X ray diffraction experiments were performed in a variable pressure range (0-100 GPa), depending on the stability field of the rhombohedral structure at ambient temperature, which is a function of the carbonate composition. The thermal expansion increases from calcite, CaCO3, \u3b10 = 4.10(7) 710-5 K-1, to magnesite, MgCO3, \u3b10 = 7.04(2) 710-5 K-1. In the magnesite-siderite (FeCO3) join, the thermal expansion decreases as iron content increases, with an experimental value of \u3b10 = 6.44(4) 710-5 K-1 for siderite. The compressibility in the ternary join is higher (i.e., lower bulk modulus) in calcite and Mg-calcite [K0 = 77(3) GPa for Ca0.91Mg0.06Fe0.03(CO3)] than in magnesite, K0 = 113(1) GPa, and siderite, K0 = 125(1) GPa. The analysis of thermal expansion and compressibility variation in calcite-magnesite and calcite-iron-magnesite joins clearly shows that the structural changes associated to the order-disorder transitions [i.e., R3c calcite-type structure vs. R3 CaMg(CO3)2 dolomite-type structure] do not affect significantly the thermal expansion and compressibility of carbonate. On the contrary, the chemical compositions of carbonates play a major role on their thermo-elastic properties. Finally, we use our P-V-T equation of state data to calculate the unit-cell volume of a natural ternary carbonate, and we compare the calculated volumes to experimental observations, measured in situ at elevated pressure and temperatures, using a multi-anvil device. The experimental and calculated data are in good agreement demonstrating that the equation of state here reported can describe the volume behavior with the accuracy needed, for example, for a direct chemical estimation of carbonates based on experimental unit-cell volume data of carbonates at high pressures and temperatures

Party-group relations in new southern European democracies in the crisis era

UID/CPO/04627/2013 PTDC/IVC-CPO/1864/2014publishersversionpublishe

“Either Everyone Was Guilty or Everyone Was Innocent”: The Italian Power Elite, Neopatrimonialism, and the Importance of Social Relations

Rarely does the Byzantine world of football administration get exposed as clearly as during the 2006 calciopoli scandal. This scandal laid bare the interpersonal relationships of football administrators at the top three Italian men’s football clubs: Juventus, Inter, and AC Milan. This article draws on the media leaks that revealed the inner workings of those working within football to argue that the football clubs are pyramids of power for club presidents that allows them to operate within the Italian power elite. This is done through interpersonal clientelistic networks that operate within a neopatrimonial system. Theoretically, this article draws on four main concepts: C. Wright Mills’s concept of the Power Elite, Lomnitz’s model of “Pyramids of Power,” Eisenstadt’s notion of neopatrimonialism, and Mauss’s utilization of the gift. Power is exercised through quid pro quo relationships, with certain key individuals operating as brokers to the flow of favors throughout the network