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Temperature and redox dual responsive prodrug nanogels for controlled drug release.

The shale gas debate has taken center stage over the past decade in many European countries due to its purported climate advantages over coal and the implications for domestic energy security. Nevertheless, shale gas production generates greenhouse gas and air pollutant emissions including carbon dioxide, methane, carbon monoxide, nitrogen oxides, particulate matter and volatile organic compounds. In this study we develop three shale gas drilling projections in Germany and the United Kingdom based on estimated reservoir productivities and local capacity. For each projection, we define a set of emission scenarios in which gas losses are assigned to each stage of upstream gas production to quantify total emissions. The “realistic” (REm) and “optimistic” (OEm) scenarios investigated in this study describe, respectively, the potential emission range generated by business-as-usual activities, and the lowest emissions technically possible according to our settings. The latter scenario is based on the application of specific technologies and full compliance with a stringent  regulatory framework described herein. Based on the median drilling projection, total annual methane emissions range between 150–294 Kt in REm and 28–42 Kt in OEm, while carbon dioxide emissions span from 5.55–7.21 Mt in REm to 3.11–3.96 Mt in OEm. Taking all drilling projections into consideration, methane leakage rates in REm range between 0.45 and 1.36% in Germany, and between 0.35 and 0.71% in the United Kingdom. The leakage rates are discussed in both the European (conventional gas) and international (shale gas) contexts. Further, the emission intensity of a potential European shale gas industry is estimated and compared to national inventories. Results from our science-based prospective scenarios can facilitate an informed discussion among the public and policy makers on the climate impact of a potential shale gas development in Europe, and on the appropriate role of natural gas in the worldwide energy transition.

We report on the molecular structures of the two most abundant conformers of n-octanal observed by molecular beam Fourier transform microwave spectroscopy. Next to limonene, which is the main component of citrus-oil, octanal and other n-alkyl aldehydes strongly enhance the typical fresh smell of lemon-oil. Due to the high flexibility of its n-alkyl chain and the high number of possible conformers, different semi-empirical methods (AM1, PM3, MMFF94) were used to sample the conformational space of octanal before performing more sophisticated quantum chemical calculations at the MP2 level of theory. This technique has previously been shown to be an ideal tool to characterize relevant odorant structures in fragrance chemistry. The structure of octanal and structurally related molecules is discussed in the context of the most abundant chain conformations and the potential use of the microwave validated structures for further studies in biological media.

No abstract

Germany and the United Kingdom have domestic shale gas reserves which they may exploit in the future to complement their national energy strategies. However gas production releases volatile organic compounds (VOC) and nitrogen oxides (NO x ), which through photochemical reaction form ground-level ozone, an air pollutant that can trigger adverse health effects e.g. on the respiratory system. This study explores the range of impacts of a potential shale gas industry in these two countries on local and regional ambient ozone. To this end, comprehensive emission scenarios are used as the basis for input to an onlinecoupled regional chemistry transport model (WRF-Chem). Here we simulate shale gas scenarios over summer (June, July, August) 2011, exploring the effects of varying VOC emissions, gas speciation, and concentration of NO x emissions over space and time, on ozone formation. An evaluation of the model setup is performed, which exhibited the model's ability to predict surface meteorological and chemical variables well compared with observations, and consistent with other studies. When different shale gas scenarios were employed, the results show a peak increase in maximum daily 8-hour average ozone from 3.7 to 28.3 μg m -3 . In addition, we find that shale gas emissions can force ozone exceedances at a considerable percentage of regulatory measurement stations locally (up to 21% in Germany and 35% in the United Kingdom) and in distant countries through long-range transport, and increase the cumulative healthrelated metric SOMO35 (maximum percent increase of ~28%) throughout the region. Findings indicate that VOC emissions are important for ozone enhancement, and to a lesser extent NO x , meaning that VOC regulation for a future European shale gas industry will be of especial importance to mitigate unfavorable health outcomes. Overall our findings demonstrate that shale gas production in Europe can worsen ozone air quality on both the local and regional scales.