A robust DNA interface on a silicon electrode

Two different interfaces prepared via UV-hydrosilylation of undecylenic acid and 1,8-nonadiyne on silicon(111) have been explored to develop a robust electrochemical DNA sensor. Electrodes modified with undecylenic acid were found to stably immobilise DNA but could not resist the growth of insulating oxides, whereas 1,8-nonadiyne modified electrodes satisfy both requirements

The low-level radial velocity variability in Barnard's star (=GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits

We report results from 2 1/2 yr of high precision radial velocity (RV) monitoring of Barnard's star. The high RV measurement precision of the VLT-UT2+UVES of 2.65 m/s made the following findings possible. (1) The first detection of the change in the RV of a star caused by its space motion (RV secular acceleration). (2) An anti-correlation of the measured RV with the strength of the filling-in of the Halpha line by emission. (3) Very stringent mass upper limits to planetary companions. Using only data from the first 2 years, we obtain a best-fit value for the RV secular acceleration of 5.15+/-0.89 m/s/yr. This agrees with the predicted value of 4.50 m/s/yr based on the Hipparcos proper motion and parallax combined with the known absolute radial velocity of the star. When the RV data of the last half-year are added the best-fit slope is strongly reduced to 2.97+/-0.51 m/s/yr suggesting the presence of additional RV variability in the star. Part of it can be attributed to stellar activity as we demonstrate by correlating the residual RVs with an index that describes the filling-in of the Halpha line by emission. A correlation coefficient of -0.50 indicates that the appearance of active regions causes a blueshift of photospheric absorption lines. Assuming that active regions basically inhibit convection we discuss the possibility that the fundamental (inactive) convection pattern in this M4V star produces a convective redshift. We also determine upper limits to the projected mass msini and to the true mass m of hypothetical planetary companions in circular orbits. For the separation range 0.017-0.98 AU we exclude any planet with msini>0.12 Mjupiter and m>0.86 Mjupiter. Throughout the habitable zone, i.e. 0.034-0.082 AU, we exclude planets with msini>7.5 Mearth and m>3.1 Mneptune.Comment: 12 pages, 8 figures, LaTeX2e, A&A macro, psfig macro, accepted by A&

Rapport I.10. Réglage des débits d’eau à haute pression et haute température

1°) Flashing in control valves. Sizing of control valves in flashing conditions. 2°) Erosion by cavitation in control valves. Cavitation noise calculations. 3°) Control valves to be used on flashing or cavitation service : — Main features ; — Rangeability ; — Tightness in closed position.1°) Phénomènes de vaporisation dans les vannes de réglage et sélection de ces vannes dans les cas de vaporisation. 2°) Effets nocifs du phénomène de cavitation dans les vannes. Méthode de calcul des bruits causés par la cavitation. 3°) Vannes de réglage préconisées actuellement dans les cas d’application ci-dessus : — Description ; — Avantages particuliers en ce qui concerne : - les possibilités de réglage, - l’étanchéité à la fermeture.Smagghe P., Rouesnel L. Rapport I.10. Réglage des débits d’eau à haute pression et haute température. In: Hydrotechnique des liquides industriels. Compte rendu des douzièmes journées de l'hydraulique. Paris, 6-8 juin 1972. Tome 1, 1973

Pots, houses and metal: technological relations at the Bronze Age tell at Százhalombatta, Hungary

At the Bronze Age tell of Százhalombatta, Hungary, techniques used for making pottery echo those used in other media. Pottery and architecture have a close relationship. Not only were both made of clay, but methods of making pots echo those used for building. Similarly, pottery and metalwork share common themes and technologies for working with clay and bronze. Since choices made by potters are not solely confined to the environment, raw materials and tools, but are also socially and culturally defined, by implication the transfer of know-how must be situated within social networks between people. This paper considers how the identification of technical relationships between different media at Százhalombatta can be used to explore social relations in Bronze Age society, thereby suggesting relationships that work on both technical and social levels