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A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm(-1). In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry.

Four RuII complexes of general formula [Ru(PT)3]2+, [Ru(NT)3]2+, [Ru(PT)(bpy)2]2+, and [Ru(NT)(bpy)2]2+, where PT = 10,13-bis((triisopropylsilyl)ethynyl)dipyrido[3,2-a:2',3'-c]phenazine, NT = 10,15-bis((triisopropylsilyl)ethynyl)benzo[i]dipyrido[3,2-a:2',3'-c]phenazine and bpy = 2,2'-bipyridine have been synthesized. Our goal is to illustrate their electrochemical and photophysical properties with the aid of DFT and TD-DFT theoretical methods, in order to evaluate their potential for applications on solar energy conversion [1]. Additionally, we want to get exhaustive photophysical data for RuII homoleptic complexes with extended ligands, which have been scarcely investigated [2]. The electrochemical data for the phenanthroline ligands PT and NT show two successive one-electron reduction processes, while in the four complexes, also according to DFT calculations, the two first reduction processes are located on the extended phenanthrolines. Both ligands display green-yellow fluorescence at 298 and 77 K, whereas a strong and long-lived phosphorescence is detected only in the case of the PT ligand. In oxygen-free THF solution at 298 K, [Ru(PT)3]2+ and [Ru(PT)(bpy)2]2+ exhibit a very weak emission band, which is unequivocally attributed to emission from the lowest triplet level centered on the PT ligand since the emission band of the complexes is virtually identical to the phosphorescence of the free ligand. The two complexes of the more extended chelator, [Ru(NT)3]2+ and [Ru(NT)(bpy)2]2+, do not emit under any conditions; only a weak fluorescence signal attributable to a slight amount of free ligand in solution is observed. Photophysical data are fully rationalized with DFT methods, which always predict that the lowest triplet excited state is centered on the extended phenanthroline ligand in all of the complexes. These RuII compounds are long wavelength light absorbers, which are potentially useful for the harvesting of solar energy. [1] Monti F., Hahn U., Pavoni E., Delavaux-Nicot B., Nierengarten J.-F., Armaroli N., Polyehdron, 2014, doi:10.1016/j.poly.2014.05.030, Special Issue on Molecular Materials for Solar Energy Conversion. [2] Puntoriero F., Nastasi F., Galletta M., Campagna S., Photophysics and Photochemistry of Non-Carbonyl-Containing Coordination and Organometallic Compounds, in: Eds. J. Reedijk, K. Poeppelmeier Comprehensive Inorganic Chemistry II (2nd Edition), Elsevier, 2013, pp. 255-337.

Abstract Purpose of Review What does recent work say about how changes in convective organization could lead to changes in extreme precipitation? Recent Findings Changing convective organization is one mechanism that could explain variation in extreme precipitation increase through dynamics. In models, the effects of convective self-aggregation on extreme precipitation are sensitive to parameterization, among other factors. In both models and observations, whether or not convective organization influences extreme precipitation is sensitive to the time and space scales analyzed, affecting extreme precipitation on some scales but not others. While trends in observations in convective organization associated with mean precipitation have been identified, it has not yet been established whether these trends are robust or relevant for events associated with extreme precipitation. Summary Recent work has documented a somewhat view of how changes in convective organization could affect extreme precipitation with warming, and it remains unclear whether or not they do.

Under the impact of natural and anthropogenic climate variability, upwelling systems are known to change their properties leading to associated regime shifts in marine ecosystems. These often impact commercial fisheries and societies dependent on them. In a region where in situ hydrographic and biological marine data are scarce, this study uses a combination of remote sensing and ocean modelling to show how a stable seasonal upwelling off the Kenyan coast shifted into the territorial waters of neighboring Tanzania under the influence of the unique 1997/98 El Niño and positive Indian Ocean Dipole event. The formation of an anticyclonic gyre adjacent to the Kenyan/Tanzanian coast led to a reorganization of the surface currents and caused the southward migration of the Somali–Zanzibar confluence zone and is attributed to anomalous wind stress curl over the central Indian Ocean. This caused the lowest observed chlorophyll-a over the North Kenya banks (Kenya), while it reached its historical maximum off Dar Es Salaam (Tanzanian waters). We demonstrate that this situation is specific to the 1997/98 El Niño when compared with other the super El-Niño events of 1972,73, 1982–83 and 2015–16. Despite the lack of available fishery data in the region, the local ecosystem changes that the shift of this upwelling may have caused are discussed based on the literature. The likely negative impacts on local fish stocks in Kenya, affecting fishers’ livelihoods and food security, and the temporary increase in pelagic fishery species’ productivity in Tanzania are highlighted. Finally, we discuss how satellite observations may assist fisheries management bodies to anticipate low productivity periods, and mitigate their potentially negative economic impacts.

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.

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