bloom dynamics depend principally on the impact of consumers, a long-recognized control of phytoplankton abundance (30). Our findings for Synechococcus agree with those of Behrenfeld and Boss in so far as division rates (and, by inference, loss rates) are roughly 10 times the accumulation (net growth) rates. Our results differ, however, in that we find a significant positive correlation between division and accumulation rates over the course of the spring bloom (Fig. 4, B and C). This correlation was not detected by Behrenfeld and Boss, and perhaps should not be expected to be evident in the satellite-based observations of chlorophyll concentration that they analyzed (29). Those observations aggregate the entire phytoplankton community over a relatively large region of the ocean and mask individual responses of different taxa.Our observations, made at a much smaller spatial scale and with much finer taxonomic and temporal resolution than that of satellite data, reveal a connection between division rates and the bloom dynamics of Synechococcus. Consumers (including grazers, viruses, and parasites) certainly play a major role in shaping the bloom's trajectory, but the bloom is triggered by an environmental factor, the seasonal temperature rise, which leads to increases in the Synechococcus division rate (Fig. 3). The bloom persists until the division rate plateaus (Fig. 4B), at which point losses overtake division and the bloom begins to decline.We were able to diagnose the importance of temperature in regulating the dynamics of a ubiquitous marine primary producer, Synechococcus, by exploiting a 13-year time series comprising data on millions of individual cells and their traits. This allowed us to not only quantify the relationship between temperature and cell division in a natural population, but also to document how that relationship is the basis for a dramatic phenological shift affecting both Synechococcus and their consumers. It remains to be seen whether this ecological coupling will hold as warming trends continue in the decades to come.

The solar-driven electrochemical reduction of CO 2 to fuels and chemicals provides a promising way for closing the anthropogenic carbon cycle. However, the lack of selective and Earth-abundant catalysts able to achieve the desired transformation reactions in an aqueous matrix presents a substantial impediment as of today. Here we introduce atomic layer deposition of SnO 2 on CuO nanowires as a means for changing the wide product distribution of CuO-derived CO 2 reduction electrocatalysts to yield predominantly CO. The activity of this catalyst towards oxygen evolution enables us to use it both as the cathode and anode for complete CO 2 electrolysis. In the resulting device, the electrodes are separated by a bipolar membrane, allowing each half-reaction to run in its optimal electrolyte environment. Using a GaInP/GaInAs/Ge photovoltaic we achieve the solar-driven splitting of CO 2 into CO and oxygen with a bifunctional, sustainable and all Earth-abundant system at an e ciency of 13.4%.T he electrochemical reduction of CO 2 to fuels and chemicals has the promise to provide a versatile way of storing renewable electrical energy in chemical bonds while simultaneously closing the anthropogenic carbon cycle. A number of products have been successfully synthesized by this process, most notably carbon monoxide (CO) 1-3 , formic acid (HCOOH), methane (CH 4 ) 4 , ethylene (C 2 H 4 ) 5 and ethanol (CH 3 CH 2 OH) 6 , as well as other compounds 7,8 . Due to the numerous possible reaction pathways, selectively targeting one specific product at high yield has remained a challenge, which, to the present day, has been achieved only for CO and formic acid in aqueous electrolytes. Unfortunately, selective electroreduction of CO 2 to these products relies on the use of precious metals (Au, Ag, Pd) [9][10][11][12] , requires operation at considerable overpotentials 13 , or requires the use of electrolyte additives, such as ionic liquids 14 . Developing inexpensive, selective and stable catalysts operating at low overpotentials is therefore a crucial requirement.Recently, substantial progress toward decreasing the overpotential of copper-based electrodes was made by employing catalysts derived from copper oxides 15 . However, the insufficient selectivity remained an issue, with the catalyst producing CO, H 2 and formic acid at comparable selectivities. Following up on this work, it was demonstrated that by electrochemically reducing copper oxide in the presence of indium ions, the selectivity toward producing CO could be substantially enhanced 16,17 . More recently, the same group demonstrated tin to have a similar effect 18 . Although adding sources of metal ions during the catalyst reduction process is effective in tuning the selectivity, it is difficult to control and may not guarantee uniform coating.Here, we demonstrate the surface modification of CuO nanowire electrodes with SnO 2 using atomic layer deposition (ALD), leading to a highly selective catalyst for the electrochemical reduction of CO 2 to CO. By using SnO 2 -modified...

We demonstrate fast characterization of the distribution of surface bonding modes and interactions in a series of functionalized materials via surface-enhanced nuclear magnetic resonance spectroscopy using dynamic nuclear polarization (DNP). Surface-enhanced silicon-29 DNP NMR spectra were obtained by using incipient wetness impregnation of the sample with a solution containing a polarizing radical (TOTAPOL). We identify and compare the bonding topology of functional groups in materials obtained via a sol-gel process and in materials prepared by post-grafting reactions. Furthermore, the remarkable gain in time provided by surface-enhanced silicon-29 DNP NMR spectroscopy (typically on the order of a factor 400) allows the facile acquisition of two-dimensional correlation spectra.