6-Bromo-1-(1,2-propadien­yl)-3-(2-propyn­yl)-1H-imidazo[4,5-b]pyridin-2(3H)-one

The reaction of propargyl bromide and 6-bromo-1,3-dihydro­imidazo[4,5-b]pyridin-2-one in refluxing dimethyl­formamide yields the title compound, C12H8BrN3O, which features nitro­gen-bound propadienyl and propynyl substituents. The imidazolopyridine fused ring is planar (r.m.s. deviation = 0.012 Å); the propadienyl chain is coplanar with the fused ring as it is conjugated with it, whereas the propynyl chain is not as the nitro­gen-bound C atom is a methyl­ene linkage. The acetyl­enic H atom is hydrogen bonded to the carbonyl O atom of an adjacent mol­ecule, forming a helical chain runnning along the b axis

1,3-Dibenzyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one

The imidazopyridine fused-ring in the title compound, C20H16BrN3O, is planar (r.m.s. deviation = 0.011 Å). The phenyl rings of the benzyl substitutents twist away from the central five-membered ring in opposite directions; the rings are aligned at 61.3 (1) and 71.2 (1)° with respect to this ring

6-Bromo-1,3-di-2-propynyl-1H-imidazo[4,5-b]pyridin-2(3H)-one

The room-temperature reaction of propargyl bromide and 6-bromo-1,3-dihydro­imidazo[4,5-b]pyridin-2-one in dimethyl­formamide yields the title compound, C12H8BrN3O, which features nitro­gen-bound propynyl substituents. The imidazopyridine fused ring is almost planar (r.m.s. deviation = 0.011 Å); the propynyl chains point in opposite directions relative to the fused ring. One acetyl­enic H atom is hydrogen bonded to the carbonyl O atom of an inversion-related mol­ecule, forming a dimer; adjacent dimers are linked by a second acetyl­ene–pyridine C—H⋯N inter­action, forming a layer motif

4-Benzyl-6-bromo-2-(4-methoxy­phen­yl)-4H-imidazo[4,5-b]pyridine monohydrate

The imidazopyridine fused ring in the title compound, C20H16BrN3O·H2O, is coplanar with the aromatic ring at the 2-position [dihedral angle = 5.2 (1)°]. In the five-membered imidazo portion, the C—N bond whose C atom is also connected to the pyridine N atom has predominantly double-bond character [1.334 (2) Å] whereas the C—N bond whose atom is connected to the pyridine C atom has predominantly single-bond character [1.371 (2) Å]. The water mol­ecule engages in hydrogen bonding with the latter N atom; it is also connected to a symmetry-related water mol­ecule, generating a linear chain structure

Population dynamics in compressible flows

Organisms often grow, migrate and compete in liquid environments, as well as on solid surfaces. However, relatively little is known about what happens when competing species are mixed and compressed by fluid turbulence. In these lectures we review our recent work on population dynamics and population genetics in compressible velocity fields of one and two dimensions. We discuss why compressible turbulence is relevant for population dynamics in the ocean and we consider cases both where the velocity field is turbulent and when it is static. Furthermore, we investigate populations in terms of a continuos density field and when the populations are treated via discrete particles. In the last case we focus on the competition and fixation of one species compared to anotherComment: 16 pages, talk delivered at the Geilo Winter School 201

Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

The Peruvian upwelling system encompasses the most intense and shallowest oxygen minimum zone (OMZ) in the ocean. This system shows pronounced submesoscale activity like filaments and fronts. We carried out glider-based observations off Peru during austral summer 2013 to investigate whether submesoscale frontal processes ventilate the Peruvian OMZ. We present observational evidence for the subduction of highly oxygenated surface water in a submesoscale cold filament. The subduction event ventilates the oxycline but does not reach OMZ core waters. In a regional submesoscale-permitting model we study the pathways of newly upwelled water. About 50% of upwelled virtual floats are subducted below the mixed layer within 5 days emphasizing a hitherto unrecognized importance of subduction for the ventilation of the Peruvian oxycline

The chlorophyll seasonal dynamics in the Black Sea as inferred from Biogeochemical-Argo floats

Biogeochemical-Argo (BGC-Argo) floats offer the opportunity to investigate the spatial and temporal dynamics of chlorophyll a (Chla) profiles. In the Black Sea, the unusual abundance of colored dissolved organic matter (CDOM) and the absence of oxygen below ∼80-100m require a revision of the classic formulation used to link the fluorescence signal and the algal chlorophyll concentration (e.g. Xing et al., 2017). Indeed, the very high content of CDOM in the basin is thought to be responsible for the apparent increase of Chla concentrations at depth, where it should be zero due to the absence of light. Here, the classic formulation to link fluorescence and Chla is revised based on a reference Chla dataset sampled during a scientific cruise onboard RV Akademik and analysed with High Performance Liquid Chromatography (HPLC). Then, using the established equation to remove the contribution of CDOM to the fluorescence signal, we estimated the Chla profiles from 4 BGC-Argo floats during the period 2014-2017. All Chla profiles were thus highly quality controlled by using the Argo documentation (Schmechtig et al., 2015). Especially, we removed bad data (e.g. spikes, outliers) and we corrected the Non-Photochemical Quenching effect, a photoprotective mechanism resulting in a decrease in the fluorescence signal at the surface. The Chla profiles are categorized based on fitting algorithms (e.g. sigmoid, exponential, gaussian) and empirical criteria. They display a large variety of shapes across the seasons (e.g. homogeneity in the mixed layer, subsurface maximum, double peaks below the surface, etc.) with roughly homogeneous profiles dominating between November and February while subsurface maxima are present during the rest of the year, with in summer a clearly-marked deep chlorophyll maximum (DCM). We then investigate the formation mechanism of DCMs based on the hysteresis hypothesis for the temperate ocean proposed by Navarro et al., (2013). For this, we looked at the correlation between the position of DCMs and the potential density anomaly of the mixed layer when it is maximum in winter, usually between February and March. We show that DCMs are highly correlated with the potential density anomaly of the previous winter mixed layer where a winter bloom initiated while the correlation with the 10% and 1% light levels is poor. This is in agreement with the hysteresis hypothesis that assumes that in regions where a bloom forms in late winter/early spring, this bloom remains established at a fixed density (i.e. the density of the mixed layer when it is maximum) until the end of summer acting as a barrier for the diffusion of nutrients from below and preventing the occurrence of deeper blooms due to a shading effect. This bloom is finally progressively eroded in autumn, when the depth of the mixed layer increases again

Copernicus Marine Service Ocean State Report

This is the final version. Available from Taylor & Francis via the DOI in this record