Source apportionment of size and time resolved trace elements and organic aerosols from an urban courtyard site in Switzerland

Time and size resolved data of trace elements were obtained from measurements with a rotating drum impactor (RDI) and subsequent X-ray fluorescence spectrometry. Trace elements can act as indicators for the identification of sources of particulate matter <10 μm (PM10) in ambient air. Receptor modeling was performed with positive matrix factorization (PMF) for trace element data from an urban background site in Zürich, Switzerland. Eight different sources were identified for the three examined size ranges (PM1-0.1, PM2.5-1 and PM 10-2.5): secondary sulfate, wood combustion, fire works, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The major component was secondary sulfate for the smallest size range; the road traffic factor was found in all three size ranges. This trace element analysis is complemented with data from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS), assessing the PM1 fraction of organic aerosols. A separate PMF analysis revealed three factors related to three of the sources found with the RDI: oxygenated organic aerosol (OOA, related to inorganic secondary sulfate), hydrocarbon-like organic aerosol (HOA, related to road traffic) and biomass burning organic aerosol (BBOA), explaining 60 %, 22 % and 17 % of total measured organics, respectively. Since different compounds are used for the source classification, a higher percentage of the ambient PM10 mass concentration can be apportioned to sources by the combination of both methods. © 2011 Author(s)

Epigenetic Engineering of Ribosomal RNA Genes Enhances Protein Production

Selection of mammalian high-producer cell lines remains a major challenge for the biopharmaceutical manufacturing industry. Ribosomal RNA (rRNA) genes encode the major component of the ribosome but many rRNA gene copies are not transcribed [1]–[5] due to epigenetic silencing by the nucleolar remodelling complex (NoRC) [6], which may limit the cell's full production capacity. Here we show that the knockdown of TIP5, a subunit of NoRC, decreases the number of silent rRNA genes, upregulates rRNA transcription, enhances ribosome synthesis and increases production of recombinant proteins. However, general enhancement of rRNA transcription rate did not stimulate protein synthesis. Our data demonstrates that the number of transcriptionally competent rRNA genes limits efficient ribosome synthesis. Epigenetic engineering of ribosomal RNA genes offers new possibilities for improving biopharmaceutical manufacturing and provides novel insights into the complex regulatory network which governs the translation machinery in normal cellular processes as well as in pathological conditions like cancer

Supporting first-grade writers who fail to learn: multiple single-case evaluation of a response to intervention approach

We report a multiple-baseline single-case study, based in the response to intervention framework, evaluating transcription-only and transcription-and-planning interventions for young, struggling writers. In a baseline phase, 8 classes of Spanish children at the start of their first year of primary (elementary) education completed short, probe writing tasks twice-weekly over the first 120 days of their school career. During this period, all students received researcher-developed classroom instruction in spelling, handwriting, and text-planning. Students then completed a battery of tests including measures of spelling, handwriting and composition quality. On the basis of writing probe tasks and test scores we identified 12 struggling writers for whose written composition performance was below the 15th percentile, relative to the full sample, whose spelling performance was below 25th percentile, and whose handwriting was poor. For the next 72 days, these students received twice-weekly, parent-delivered training in transcription skills (handwriting and spelling) or transcription skills plus text planning. Researcher-developed classroom instruction and regular probe tasks continued during this phase. All students, in both intervention conditions, showed improvement in handwriting quality relative to Phase 1. 10 students also showed improvement in composition quality, with 8 performing, post intervention, within normal range relative to peers. Our findings demonstrate the value of a response-to-intervention approach to identification and remediation for struggling writes in their first school year

Analyse de métaux traces dans les produits pétroliers, état de l'art

Après une brève introduction sur la problématique des métaux traces dans l'industrie pétrolière, un retour sur les trois techniques majeures de dosages des métaux traces dans les produits pétroliers est présenté reprenant les travaux effectués dans les dix dernières années. Ainsi les différents types d'introduction, utilisés pour la spectrométrie d'absorption atomique avec four électrothermique (GFAAS), la spectrométrie d'émission atomique par plasma à couplage inductif (ICP-OES) et la spectrométrie de masse par plasma à couplage inductif (ICP-MS), sont repris et comparés en terme de limite de détection atteinte. Les applications sont diverses et touchent la totalité des produits pétroliers, du biocarburant en passant par l'éthanol, aux plus classiques essences et gazoles, allant jusqu'aux produits plus lourds que sont les bitumes. Une revue sur les principaux couplages possibles permet d'entrevoir les différentes possibilités que ces techniques pourront offrir dans les années à venir en terme de spéciation des métaux dans les produits pétroliers

Zn(II), Mn(II) and Sr(II) Behavior in a Natural Carbonate Reservoir System. Part II: Impact of Geological CO

Some key points still prevent the full development of geological carbon sequestration in underground formations, especially concerning the assessment of the integrity of such storage. Indeed, the consequences of gas injection on chemistry and petrophysical properties are still much discussed in the scientific community, and are still not well known at either laboratory or field scale. In this article, the results of an experimental study about the mobilization of Trace Elements (TE) during CO2 injection in a reservoir are presented. The experimental conditions range from typical storage formation conditions (90 bar, supercritical CO2) to shallower conditions (60 and 30 bar, CO2 as gas phase), and consider the dissolution of the two carbonates, coupled with the sorption of an initial concentration of 10−5 M of Zn(II), and the consequent release in solution of Mn(II) and Sr(II). The investigation goes beyond the sole behavior of TE in the storage conditions: it presents the specific behavior of each element with respect to the pressure and the natural carbonate considered, showing that different equilibrium concentrations are to be expected if a fluid with a given concentration of TE leaks to an upper formation. Even though sorption is evidenced, it does not balance the amount of TE released by the dissolution process. The increase in porosity is clearly evidenced as a linear function of the CO2 pressure imposed for the St-Emilion carbonate. For the Lavoux carbonate, this trend is not confirmed by the 90 bar experiment. A preferential dissolution of the bigger family of pores from the preexisting porosity is observed in one of the samples (Lavoux carbonate) while the second one (St-Emilion carbonate) presents a newly-formed family of pores. Both reacted samples evidence that the pore network evolves toward a tubular network type

Zn(II), Mn(II) and Sr(II) Behavior in a Natural Carbonate Reservoir System. Part I: Impact of Salinity, Initial pH and Initial Zn(II) Concentration in Atmospheric Conditions

The sorption of inorganic elements on carbonate minerals is well known in strictly controlled conditions which limit the impact of other phenomena such as dissolution and/or precipitation. In this study, we evidence the behavior of Zn(II) (initially in solution) and two trace elements, Mn(II) and Sr(II) (released by carbonate dissolution) in the context of a leakage from a CO2 storage site. The initial pH chosen are either equal to the pH of the water-CO2 equilibrium (~ 2.98) or equal to the pH of the water-CO2-calcite system (~ 4.8) in CO2 storage conditions. From this initial influx of liquid, saturated or not with respect to calcite, the batch experiments evolve freely to their equilibrium, as it would occur in a natural context after a perturbation. The batch experiments are carried out on two natural carbonates (from Lavoux and St-Emilion) with PCO2 = 10−3.5 bar, with different initial conditions ([Zn(II)]i from 10−4 to 10−6 M, either with pure water or 100 g/L NaCl brine). The equilibrium regarding calcite dissolution is confirmed in all experiments, while the zinc sorption evidenced does not always correspond to the two-step mechanism described in the literature. A preferential sorption of about 10% of the concentration is evidenced for Mn(II) in aqueous experiments, while Sr(II) is more sorbed in saline conditions. This study also shows that this preferential sorption, depending on the salinity, is independent of the natural carbonate considered. Then, the simulations carried out with PHREEQC show that experiments and simulations match well concerning the equilibrium of dissolution and the sole zinc sorption, with log KZn(II) ~ 2 in pure water and close to 4 in high salinity conditions. When the simulations were possible, the log K values for Mn(II) and Sr(II) were much different from those in the literature obtained by sorption in controlled conditions. It is shown that a new conceptual model regarding multiple Trace Elements (TE) sorption is required, to enable us to better understand the fate of contaminants in natural systems