Evaluation of a pulsed glow discharge time-of-flight mass spectrometer as a detector for gas chromatography and the influence of the glow discharge source parameters on the information volume in chemical speciation analysis

The figures of merit of a pulsed glow discharge time-of-flight mass spectrometer (GD-TOFMS) as a detector for gas chromatography (GC) analysis were evaluated. The mass resolution for the GD-TOFMS was determined on FWHM in the high mass range (208Pb+) as high as 5,500. Precision of 400 subsequent analyses was calculated on 63Cu+ to be better than 1% RSD with no significant drift over the time of the analysis. Isotope precision based on the 63Cu+/65Cu+ ratio over 400 analyses was 1.5% RSD. The limits of detection for gaseous analytes (toluene in methanol as solvent) were determined to be as low as several hundred ppb or several hundred pg absolute without using any pre-concentration technique. Furthermore, the different GD source parameters like capillary distance, cathode-anode spacing, and GD source pressure with regards to the accessible elemental, structural, and molecular information were evaluated. It was demonstrated that each of these parameters has severe influence on the ratio of elemental, structural, and parent molecular information in chemical speciation analysi

Zukünftige Geschäftsmodelle

Im Rahmen der Initiative Wald & Holz 4.0 hat die Berner Fachhochschule ein Vorgehen entwickelt, das die Unternehmen der Holzbranche bei der Weiterentwicklung ihrer Geschäftsmodelle im Kontext der digitalen Transformation unterstützen kann

L’Indice de Biodiversité Potentielle (IBP): Un outil d’aide à la gestion forestière et à la restauration écologique

Les Semaines forestières méditerranéenne (SFM) ont été conçue comme une plateforme commune pour la coopération régionale sur les forêts méditerranéennes, visant à améliorer le dialogue entre la communauté de recherche, les décideurs politiques et les acteurs concernés ainsi qu'à communiquer à la communauté internationale et à la société dans son ensemble l'importance des forêts méditerranéennes et les défis qui les affectent. La 5e Semaine forestière méditerranéenne a eu lieu au Maroc en mars 2017, sur la question de la Restauration des forêts et paysages en Méditerranée. L'AIFM y a eu en charge la création et la gestion du site internet, la gestion des inscriptions et l'appui à l'organisation générale. Elle s'est également inpliquée dans le contenu, avec la co-organisation de trois sessions d'études de cas de la restauration en Méditerranée. Cette semaine a également permis à l'AIFM de célébrer son 20e anniversaire, et d'informer largement sur les résultats de son projet MEDFORVAL grâce à un stand et un évènement parallèle spécifique

Recherche & Développement sur un outil de gestion forestière : l’Indice de Biodiversité Potentielle (IBP)

Pour intégrer la biodiversité dans la gestion courante des forêts, les gestionnaires ont besoin d’outils adaptés à leurs besoins et à leurs contraintes, et fondés sur des connaissances scientifiques solides. C’est dans cette perspective que l’Indice de Biodiversité Potentielle (IBP) a été créé en 2008 pour aider les gestionnaires de forêts tempérées à diagnostiquer aisément la biodiversité taxonomique ordinaire de leurs parcelles et à l’intégrer dans leurs choix sylvicoles. L’IBP a été présenté à la communauté forestière lors du XIIIe CFM. Depuis cette date, l’IBP s’est enrichi et fortement développé en France, grâce à un programme original de Recherche & Développement (R&D), soutenu par le ministère de l’Écologie, du Développement durable et de l’Énergie. Ainsi, l’IBP a pris une place spécifique dans la foresterie française, qui doit beaucoup à un fonctionnement en réseau associant contributeurs et utilisateurs (chercheurs, propriétaires, professionnels de la filière bois et de l’environnement, administrations, etc.). Le programme de recherche vise à améliorer la pertinence et l’ergonomie de l’IBP, à intégrer les connaissances nouvelles et à compléter les connaissances sur les facteurs déterminants pour la biodiversité tandis que le programme de développement vise à faire connaître l’IBP et à prendre en compte les attentes des praticiens de terrain. Les productions de ce programme sont donc variées : (i) publications scientifiques sur plusieurs composantes de l’IBP et sur la calibration de l’outil avec une approche pluritaxonomique ; (ii) mises à jour de l’IBP et compléments pratiques ; (iii) avancées méthodologiques ; (iv) formations. La cohérence de cette démarche intégrée de R&D explique le succès de l’IBP. Les premiers contacts établis en Europe présagent d’un possible développement à l’échelle européenne, dans des contextes bioclimatiques proches, pour répondre au besoin de prise en compte de la biodiversité ordinaire

Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS

In September 2017, we conducted a proton-transfer-reaction mass-spectrometry (PTR-MS) intercomparison campaign at the CESAR observatory, a rural site in the central Netherlands near the village of Cabauw. Nine research groups deployed a total of 11 instruments covering a wide range of instrument types and performance. We applied a new calibration method based on fast injection of a gas standard through a sample loop. This approach allows calibrations on timescales of seconds, and within a few minutes an automated sequence can be run allowing one to retrieve diagnostic parameters that indicate the performance status. We developed a method to retrieve the mass-dependent transmission from the fast calibrations, which is an essential characteristic of PTR-MS instruments, limiting the potential to calculate concentrations based on counting statistics and simple reaction kinetics in the reactor/drift tube. Our measurements show that PTR-MS instruments follow the simple reaction kinetics if operated in the standard range for pressures and temperature of the reaction chamber (i.e. 1-4 mbar, 30-120 degrees, respectively), as well as a reduced field strength E/N in the range of 100-160 Td. If artefacts can be ruled out, it becomes possible to quantify the signals of uncalibrated organics with accuracies better than +/- 30 %. The simple reaction kinetics approach produces less accurate results at E/N levels below 100 Td, because significant fractions of primary ions form water hydronium clusters. Deprotonation through reactive collisions of protonated organics with water molecules needs to be considered when the collision energy is a substantial fraction of the exoergicity of the proton transfer reaction and/or if protonated organics undergo many collisions with water molecules.Peer reviewe

Phosphate Starvation Triggers Production and Secretion of an Extracellular Lipoprotein in Caulobacter crescentus

Life in oligotrophic environments necessitates quick adaptive responses to a sudden lack of nutrients. Secretion of specific degradative enzymes into the extracellular medium is a means to mobilize the required nutrient from nearby sources. The aquatic bacterium Caulobacter crescentus must often face changes in its environment such as phosphate limitation. Evidence reported in this paper indicates that under phosphate starvation, C. crescentus produces a membrane surface-anchored lipoprotein named ElpS subsequently released into the extracellular medium. A complete set of 12 genes encoding a type II secretion system (T2SS) is located adjacent to the elpS locus in the C. crescentus genome. Deletion of this T2SS impairs release of ElpS in the environment, which surprisingly remains present at the cell surface, indicating that the T2SS is not involved in the translocation of ElpS to the outer membrane but rather in its release. Accordingly, treatment with protease inhibitors prevents release of ElpS in the extracellular medium suggesting that ElpS secretion relies on a T2SS-secreted protease. Finally, secretion of ElpS is associated with an increase in alkaline phosphatase activity in culture supernatants, suggesting a role of the secreted protein in inorganic phosphate mobilization. In conlusion, we have shown that upon phosphate starvation, C. crescentus produces an outer membrane bound lipoprotein, ElpS, which is further cleaved and released in the extracellular medium in a T2SS-dependent manner. Our data suggest that ElpS is associated with an alkaline phosphatase activity, thereby allowing the bacterium to gather inorganic phosphates from a poor environment

Influence of temperature on the molecular composition of ions and charged clusters during pure biogenic nucleation

It was recently shown by the CERN CLOUD experiment that biogenic highly oxygenated molecules (HOMs) form particles under atmospheric conditions in the absence of sulfuric acid, where ions enhance the nucleation rate by 1-2 orders of magnitude. The biogenic HOMs were produced from ozonolysis of alpha-pinene at 5 degrees C. Here we extend this study to compare the molecular composition of positive and negative HOM clusters measured with atmospheric pressure interface time-of-flight mass spectrometers (APi-TOFs), at three different temperatures (25, 5 and -25 degrees C). Most negative HOM clusters include a nitrate (NO3-) ion, and the spectra are similar to those seen in the nighttime boreal forest. On the other hand, most positive HOM clusters include an ammonium (NH4+) 4) ion, and the spectra are characterized by mass bands that differ in their molecular weight by similar to 20 C atoms, corresponding to HOM dimers. At lower temperatures the average oxygen to carbon (O : C) ratio of the HOM clusters decreases for both polarities, reflecting an overall reduction of HOM formation with decreasing temperature. This indicates a decrease in the rate of autoxidation with temperature due to a rather high activation energy as has previously been determined by quantum chemical calculations. Furthermore, at the lowest temperature (-25 degrees C), the presence of C-30 clusters shows that HOM monomers start to contribute to the nucleation of positive clusters. These experimental findings are supported by quantum chemical calculations of the binding energies of representative neutral and charged clusters.Peer reviewe

Scaling of charged particle multiplicity in Pb-Pb collisions at SPS energies

The charged particle multiplicity distribution $dN_{ch}/d\eta$ has been measured by the NA50 experiment in Pb--Pb collisions at the CERN SPS. Measurements were done at incident energies of 40 and 158 GeV per nucleon over a broad impact parameter range. The multiplicity distributions are studied as a function of centrality using the number of participating nucleons ($N_{part}$), or the number of binary nucleon--nucleon collisions ($N_{coll}$). Their values at midrapidity exhibit a power law scaling behaviour given by $N_{part}^{1.00}$ and $N_{coll}^{0.75}$ at 158 GeV. Compatible results are found for the scaling behaviour at 40 GeV. The width of the $dN_{ch}/d\eta$ distributions is larger at 158 than at 40 GeV/nucleon and decreases slightly with centrality at both energies. Our results are compared to similar studies performed by other experiments both at the CERN SPS and at RHIC.

Results on Charmonium States in Pb-Pb Interactions

We present cross-sections for J/$\psi$, $\psi^{\prime}$ and Drell-Yan production in lead-lead interactions at 158 GeV/nucleon. The Pb-Pb data, when compared with previous results obtained with lighter target or projectiles, show a similar behaviour for Drell-Yan, but exhibit an anomalous J/$\psi$ suppression, which increases with centrality

Intermediate mass dimuons in NA38/NA50

The NA38/NA50 experiments have measured, at the CERN SPS, the dimuon production in proton-nucleus and nucleus-nucleus collisions. In this paper it is shown that the mass continuum between the $\phi$ and the $J/{\psi}$ can be satisfactorily described, after having removed the combinatorial background due to uncorrelated $\pi$ and $K$ decays, as a sum of two contributions, namely the Drell-Yan process and the semi-leptonic decay of pairs of charmed mesons, whose mass shape in the acceptance of the experiment has been evaluated using PYTHIA. However, in order to describe the A - B (namely S - U and Pb - Pb) mass spectra, the dimuon yield from open charm decays, which in $p$ - A collisions is found to be consistent with direct open charm measurements from other CERN and FNAL experiments, has to be enhanced with respect to a linear extrapolation of $p$ - A results. The size of the enhancement smoothly increases from peripheral S - U to central Pb - Pb interactions, reaching a factor $\sim$ 3 in central Pb - Pb collisions. The $P_{T}$ distributions of the events in the mass continuum are also compatible with the hypothesis of open charm enhancement in A - B collisions