Nitrogenase activity associated with codium species from New Zealand marine habitats

Nitrogenase activity, measured as acetylene reduction, was recorded at rates up to 1028 nmol.h \g * dry weight for Codium adhaerens (Cabr.) Ag. var. convolutum Dellow and Codium fragile (Sur.) Hariot subsp. tomentosoides (Van Goor) Silva collected from New Zealand habitats. In both species the ability to reduce acetylene is invariably associated with the presence of a heterocystous blue-green alga, Calothrix sp., epiphytic or embedded in the Codium thallus. A highly significant (P < 0.001) correlation between heterocyst frequency and nitrogenase activity was found. Nitrogenase and net photosynthesis of the Codium-Calothrix system have different steady-state responses to light intensity, and the kinetics of the two processes also differ in that nitrogenase is slow to respond to illumination or darkening. Glucose additions to Codium did not significantly increase nitrogenase activity. Nitrogenase is relatively insensitive to oxygen tension over the range 0-1.0 atm (0-1.033 kgf.cnT2) and still occurs at 1.5 atm (1.55 kgf.cm"2); this condition is unique in all nitrogenase systems thus far reported. Collectively these facts suggest that Calothrix is the agent primarily responsible for nitrogenase activity in these Codium species

Crack tip fields in elastic-plastic and mixed mode I+II+III conditions, finite elements simulations and modeling

This paper is devoted to the analysis of the load path effect on I+II+III mixed mode fatigue crack propagation in a 316L stainless steel. Experiments were conducted in mode I+II and in mode I+II+III. The same maximum, minimum and mean values of the stress intensity factors were used for each loading path in the experiments. The main result of this set of experiments is that very different crack growth rates and crack paths are observed for load paths that are however considered as equivalent in most fatigue criteria. The experiments conducted in mode I+II and in mode I+II+III, also allowed to show that the addition of mode III loading steps to a mode I+II loading sequence is increasing the fatigue crack growth rate, even when the crack path is not significantly modified

2005 French Salmonella Network data on antimicrobial resistance in the swine channels

The Salmonella Network is gathering, on a voluntary participation scheme, from approximately 150 public and private laboratories dissemmated throughout France, Salmonella strains and/or epidemiological information. Those non-human Salmonella strains are isolated either from animal health and production or food, feed and the environment sectors. Thus, in 2005, a total of 527 isolations from the swine channels were reported. The top 5 prevalent serotypes were : Typhimurium, Derby, Manhattan, lnfantis and Kedougou. Two-hundred and ninety five strains were received at the laboratory and, after double clearance, 185 strains were tested for their antimicrobial resistance against 16 antibiotics by the disk diffusion method. Twenty-one strains were associated to the animal health and production sector and 164 to the food sector

Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure

Les Laboratoires de chimie

Data del Supplément: 1882Pag.: v.1: 145 p.; v.2: 74 p.; v.3: [81] f. de làm.Conté: v. 1: Texte -- v. 2: Supplément / Henrivaux, Girard et Pabst -- v. 3: Atla

What's in a name? - A short history of coordination chemistry from then to now

This article traces the development of coordination chemistry and shows how progress in the science has been paralleled by the development of a vocabulary and nomenclature to describe new concepts, structural features and compound types

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Peer reviewedPublisher PD

Risks to human and animal health related to the presence of moniliformin in food and feed

The CONTAM Panel wishes to acknowledge all European competent authorities and other stakeholders that provided occurrence data on moniliformin in food and feed, and supported the consumption data collection for the Comprehensive European Food Consumption Database. Adopted: 21 November 2017Peer reviewedPublisher PD

Fatigue Crack Initiation and Propagation

The resistance of metal alloys to fatigue can be classified into four major regimes: low-cycle fatigue (or short life), limited resistance (between 10^5 and 10^6 cycles), high-cycle fatigue (between 10^6 and 10^7 cycles) and gigacycle (more than 10^7 cycles). This chapter introduces the basic concepts of cyclic mechanical behavior, crack initiation and propagation in these different regimes