SIRANE modeling of oxides nitrogen (NOx) and ozone (O3) in the area of Agadir city, southwestern Morocco.

This work aimed to model the dispersion of the traffic emissions for the first time in the area of Agadir city (Morocco). The estimate of road emission (from vehicle counts) was performed with Circul’air software version 4.0 which is based on the European methodology Copert 4. While the dispersion modelling was performed using SIRANE model, an important tool which adopts the classic NOx photochemical process. The input data are pollutant emissions, background concentrations, meteorological parameters and building configuration data from QGIS software as well as a list of other factors such as latitude, albedo, etc.   Finally, the quality of the output results was validated by comparing observed measurements and modelled data

Intercomparison of the comparative reactivity method (CRM) and pump-probe technique for measuring total OH reactivity in an urban environment

The investigation of hydroxyl radical (OH) chemistry during intensive field campaigns has led to the development of several techniques dedicated to ambient measurements of total OH reactivity, which is the inverse of the OH lifetime. Three techniques are currently used during field campaigns, including the total OH loss rate method, the pump-probe method, and the comparative reactivity method. However, no formal intercomparison of these techniques has been published so far, and there is a need to ensure that measurements of total OH reactivity are consistent among the different techniques. An intercomparison of two OH reactivity instruments, one based on the comparative reactivity method (CRM) and the other based on the pump-probe method, was performed in October 2012 in a NOx-rich environment, which is known to be challenging for the CRM technique. This study presents an extensive description of the two instruments, the CRM instrument from Mines Douai (MD-CRM) and the pump-probe instrument from the University of Lille (UL-FAGE), and highlights instrumental issues associated with the two techniques. It was found that the CRM instrument used in this study underestimates ambient OH reactivity by approximately 20 % due to the photolysis of volatile organic compounds (VOCs) inside the sampling reactor; this value is dependent on the position of the lamp within the reactor. However, this issue can easily be fixed, and the photolysis of VOCs was successfully reduced to a negligible level after this intercomparison campaign. The UL-FAGE instrument may also underestimate ambient OH reactivity due to the difficulty to accurately measure the instrumental zero. It was found that the measurements are likely biased by approximately 2 s-1, due to impurities in humid zero air. Two weeks of ambient sampling indicate that the measurements performed by the two OH reactivity instruments are in agreement, within the measurement uncertainties for each instrument, for NOx mixing ratios up to 100 ppbv. The CRM technique has hitherto mainly been used in low-NOx environments, i.e. environments with ambient NOx mixing ratios lower than a few ppbv, due to a measurement artifact generated by ambient NO inside the sampling reactor. However, this study shows that this technique can also be used under NOx-rich conditions if a NOx-dependent correction is carefully applied on the OH reactivity measurements. A full suite of 52 VOCs, NOx, and other inorganic species were monitored during this intercomparison. An investigation of the OH reactivity budget for this urban site suggests that this suite of trace gases can account for the measured total OH reactivity

Adenylyl Cyclase Plays a Regulatory Role in Development, Stress Resistance and Secondary Metabolism in Fusarium fujikuroi

The ascomycete fungus Fusarium fujikuroi (Gibberella fujikuroi MP-C) produces secondary metabolites of biotechnological interest, such as gibberellins, bikaverin, and carotenoids. Production of these metabolites is regulated by nitrogen availability and, in a specific manner, by other environmental signals, such as light in the case of the carotenoid pathway. A complex regulatory network controlling these processes is recently emerging from the alterations of metabolite production found through the mutation of different regulatory genes. Here we show the effect of the targeted mutation of the acyA gene of F. fujikuroi, coding for adenylyl cyclase. Mutants lacking the catalytic domain of the AcyA protein showed different phenotypic alterations, including reduced growth, enhanced production of unidentified red pigments, reduced production of gibberellins and partially derepressed carotenoid biosynthesis in the dark. The phenotype differs in some aspects from that of similar mutants of the close relatives F. proliferatum and F. verticillioides: contrary to what was observed in these species, ΔacyA mutants of F. fujikuroi showed enhanced sensitivity to oxidative stress (H2O2), but no change in heavy metal resistance or in the ability to colonize tomato tissue, indicating a high versatility in the regulatory roles played by cAMP in this fungal group

Cyclic AMP signalling pathways in the regulation of uterine relaxation

Studying the mechanism(s) of uterine relaxation is important and will be helpful in the prevention of obstetric difficulties such as preterm labour, which remains a major cause of perinatal mortality and morbidity. Multiple signalling pathways regulate the balance between maintaining relative uterine quiescence during gestation, and the transition to the contractile state at the onset of parturition. Elevation of intracellular cyclic AMP promotes myometrial relaxation, and thus quiescence, via effects on multiple intracellular targets including calcium channels, potassium channels and myosin light chain kinase. A complete understanding of cAMP regulatory pathways (synthesis and hydrolysis) would assist in the development of better tocolytics to delay or inhibit preterm labour. Here we review the enzymes involved in cAMP homoeostasis (adenylyl cyclases and phosphodiesterases) and possible myometrial substrates for the cAMP dependent protein kinase. We must emphasise the need to identify novel pharmacological targets in human pregnant myometrium to achieve safe and selective uterine relaxation when this is indicated in preterm labour or other obstetric complications

Ephrin-A5 and EphA5 Interaction Induces Synaptogenesis during Early Hippocampal Development

Synaptogenesis is a fundamental step in neuronal development. For spiny glutamatergic synapses in hippocampus and cortex, synaptogenesis involves adhesion of pre and postsynaptic membranes, delivery and anchorage of pre and postsynaptic structures including scaffolds such as PSD-95 and NMDA and AMPA receptors, which are glutamate-gated ion channels, as well as the morphological maturation of spines. Although electrical activity-dependent mechanisms are established regulators of these processes, the mechanisms that function during early development, prior to the onset of electrical activity, are unclear. The Eph receptors and ephrins provide cell contact-dependent pathways that regulate axonal and dendritic development. Members of the ephrin-A family are glycosyl-phosphatidylinositol-anchored to the cell surface and activate EphA receptors, which are receptor tyrosine kinases.Here we show that ephrin-A5 interaction with the EphA5 receptor following neuron-neuron contact during early development of hippocampus induces a complex program of synaptogenic events, including expression of functional synaptic NMDA receptor-PSD-95 complexes plus morphological spine maturation and the emergence of electrical activity. The program depends upon voltage-sensitive calcium channel Ca2+ fluxes that activate PKA, CaMKII and PI3 kinase, leading to CREB phosphorylation and a synaptogenic program of gene expression. AMPA receptor subunits, their scaffolds and electrical activity are not induced. Strikingly, in contrast to wild type, stimulation of hippocampal slices from P6 EphA5 receptor functional knockout mice yielded no NMDA receptor currents.These studies suggest that ephrin-A5 and EphA5 signals play a necessary, activity-independent role in the initiation of the early phases of synaptogenesis. The coordinated expression of the NMDAR and PSD-95 induced by eprhin-A5 interaction with EphA5 receptors may be the developmental switch that induces expression of AMPAR and their interacting proteins and the transition to activity-dependent synaptic regulation

G-protein signaling: back to the future

Heterotrimeric G-proteins are intracellular partners of G-protein-coupled receptors (GPCRs). GPCRs act on inactive Gα·GDP/Gβγ heterotrimers to promote GDP release and GTP binding, resulting in liberation of Gα from Gβγ. Gα·GTP and Gβγ target effectors including adenylyl cyclases, phospholipases and ion channels. Signaling is terminated by intrinsic GTPase activity of Gα and heterotrimer reformation — a cycle accelerated by ‘regulators of G-protein signaling’ (RGS proteins). Recent studies have identified several unconventional G-protein signaling pathways that diverge from this standard model. Whereas phospholipase C (PLC) β is activated by Gαq and Gβγ, novel PLC isoforms are regulated by both heterotrimeric and Ras-superfamily G-proteins. An Arabidopsis protein has been discovered containing both GPCR and RGS domains within the same protein. Most surprisingly, a receptor-independent Gα nucleotide cycle that regulates cell division has been delineated in both Caenorhabditis elegans and Drosophila melanogaster. Here, we revisit classical heterotrimeric G-protein signaling and explore these new, non-canonical G-protein signaling pathways

FIR FT ABSORPTION SPECTROSCOPY OF SHORT-LIVED SPECIES OF ASTRONOMICAL INTEREST

Author Institution: Minamisaku, Nagano, 384-13 Japan; The Graduate University for Advanced Studies, Minamisaku, Nagano, 384-13 JapanHigh resolution FT spectroscopy has been applied for the first time to the detection of short- lived species in the far infrared region. It has allowed us to measure the rotational spectrum of OH, SH, and $NH_{2}$, as well as the vibrational spectrum of hydroxylamine $NH_{2}OH$ in the region of the torsion mode $\nu_{9}$ (band center at $386 cm^{-1}$), of which it is the first direct high resolution observation. This technique proved really efficient, and absorption of up to 20% have been obtained using a multiple-pass cell. The large transition moment of the rotational lines in this region compensates for the relatively high noise level. The sensitivity has been estimated to be of the order of $10^{9} mol/cm^{3}$, which is about two orders of magnitude below the most sensitive techniques, such as FIR-LMR. Owing to its wide spectral coverage, FIR-FT spectroscopy is thus suitable for the systematic study of short-lived species

Méthodes de mesure du formaldéhyde

La quantification du formaldéhyde dans l'air peut s'effectuer par tout un ensemble de techniques différentes, chacune étant adaptée à une problématique particulière. Cet article vise à donner un panorama des principales techniques utilisées, avec leur potentiel et leurs limitations, ainsi que leur champ d'application privilégié. En parallèle avec les méthodes classiques, souvent lourdes à mettre en oeuvre, et ne permettant pas l'accès aux variations rapides de concentration dans l'air, nous insisterons sur les développements récents très prometteurs dans le domaine des capteurs chimiques

Pollution particulaire dans les rames de métro de Lille

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The infrared emission spectrum of SiN between 2.2 and 4.4 μ\mum

The emission spectrum of a plasma of silane and nitrogen, excited by a radio frequency discharge, has been recorded with a high resolution Fourier transform spectrometer. We report here the first observation by IR spectroscopy of the X $^2 \Sigma^+ (v=1, 2)$ and A $^2 \Pi_{\rm i} (v=2, 3, 4)$ vibrational levels of $^{28}$Si$^{14}$N, through the observation of 724 unperturbed transitions of the (1-0), (2-0), (2-1), (3-1), and (4-2) vibronic bands of the A $^2 \Pi_{\rm i}$ – X $^2 \Sigma^+$ system of this radical. The data were analyzed in a least squares fit procedure, with a standard deviation equal to $6\times10^{-4}$ cm$^{-1}$