A Hubble Space Telescope Survey for Resolved Companions of Planetary-Nebula Nuclei

We report results of an HST "snapshot" survey aimed at finding resolved binary companions of the central stars of Galactic planetary nebulae (PNe). Using WF/PC and WFPC2, we searched the fields of 113 PNe for stars whose close proximity to the central star suggests a physical association. We find 10 binary nuclei that are very likely to be physically associated, and another six that are possible binary associations. By correcting for interstellar extinction and placing the central stars' companions on the main sequence, we derive distances to the objects, and thereby significantly increase the number of PNe with reliable distances. Comparison of our derived distances with those obtained from various statistical methods shows that all of the latter have systematically overestimated the distances, by factors ranging up to a factor of two or more. We show that this error is most likely due to the fact that the properties of our PNe with binary nuclei are systematically different from those of PNe used heretofore to calibrate statistical methods. Specifically, our PNe tend to have lower surface brightnesses at the same physical radius than the traditional calibration objects. This difference may arise from a selection effect: the PNe in our survey are typically nearby, old nebulae, whereas most of the objects that calibrate statistical techniques are low-latitude, high-surface-brightness, and more distant nebulae. As a result, the statistical methods that seem to work well with samples of distant PNe, e.g., those in the Galactic bulge or external galaxies, may not be applicable to the more diverse population of local PNe.Comment: 37 text pages, 17 table pages, 9 figures. Accepted by Astronomical Journal for June 1999 issu

Contribution à l'étude de quelques variétés de Figuiers des Alpes-Maritimes et du Var.

Simonet M., Chopinet R., Baccialone J. Contribution à l'étude de quelques variétés de Figuiers des Alpes-Maritimes et du Var.. In: Revue de botanique appliquée et d'agriculture coloniale, 25ᵉ année, bulletin n°275-276, Septembre-octobre 1945. pp. 44-72

Imaging living cells surface and quantifying its properties at high resolution using AFM in QI (TM) mode

International audienceSince the last 10 years, AFM has become a powerful tool to study biological samples. However, the classical modes offered (imaging or tapping mode) often damage sample that are too soft or loosely immobilized. If imaging and mechanical properties are required, it requests long recording time as two different experiments must be conducted independently. In this study we compare the new QI (TM) mode against contact imaging mode and force volume mode, and we point out its benefit in the new challenges in biology on six different models: Escherichia coli, Candida albicans, Aspergillus fumigatus, Chinese hamster ovary cells and their isolated nuclei, and human colorectal tumor cells

Soda-lime-silica glass containers: Chemical durability and weathering products

In a previous paper the weathering of the internal surface of empty glass containers before filling was investigated. Several phenomena were identified and described such as leaching of modifiers, formation of a hydrated leached layer and of crystalline deposits mainly consisting of Ca-carbonates and Na-carbonates. Localised glass surface corrosion was sometimes also detected. The role of the storage conditions, time, temperature, relative humidity and concentrations of pollutant gases (CO2, SO2), in the weathering phenomena was highlighted [1]. In the present work the composition of the weathered glass layer and the nature of the crystalline deposits are investigated. Furthermore, in order to examine more closely the weathering mechanisms and their causes, the correlation between durability laboratory tests and chemical composition of soda-lime-silica glass are discussed. © 2008 Trans Tech Publications