Solar-energy-driven conversion of CO 2 into hydrocarbon fuels can simultaneously generate chemical fuels to meet energy demand and mitigate rising CO 2 levels. The utilization of the clean and renewable solar power resource is, on a longterm basis, an essential component of solutions to address growing global energy demand, which is projected to be 40 TW by 2050. [1] This is because the solar energy received on the earths surface in one hour exceeds current total global energy demand. From the perspective of climate change, expansion of the current fossil fuel-based energy infrastructure to meet the projected energy demand is predicted to add 2986-7402 Gt of CO 2 to the atmosphere by 2100, resulting in a mean rise in global temperature of 2.4-4.5 8C. [2] Since the discovery of the photoreduction of carbon dioxide to form organic compounds using semiconductors by Fujishima and co-workers in 1979, [3] a growing interest in the development of catalysts that are capable of solar-based capture and storage of CO 2 has evolved. [4] Titanium dioxide, which is a cost-efficient, non-toxic and abundant n-type semiconductor, has been widely considered in the solar-driven reduction of CO 2 . Owing to its large band-gap energy of 3-3.2 eV, TiO 2 without doping or post-synthesis treatments can absorb only the ultraviolet portion of the solar spectrum. To narrow the band-gap of TiO 2 and improve its photocatalytic performance, strategies such as compositional doping or deliberately introducing disorder in crystalline TiO 2 are being investigated. [5] Herein, we demonstrate an approach that is able to achieve high-rate sunlight-driven conversion of diluted CO 2 to light hydrocarbons in which an optimized combination of a Cu-Pt coating and modulated-diameter TiO 2 nanotubes are used as the photocatalyst. We demonstrate at least a fourfold improvement in CO 2 conversion rates over prior art [6] by using a catalyst consisting of coaxial Cu-Pt bimetallic shells supported on a periodically modulated double-walled TiO 2 nanotube (PMTiNT) array core. The photocatalytic reaction occurs at room temperature and generates CH 4 , C 2 H 4 , and C 2 H 6 as reaction products. Under AM 1.5 one-sun illumination, using 99.9 % CO 2 , we obtained a hydrocarbon production rate of 3.51 mL g À1 h À1 or 574 nmol cm À2 h À1 . A key novelty is the effectiveness of our photocatalyst for the photoreduction of unconcentrated CO 2 . When the Cu 0.33 -Pt 0.67 /PMTiNT heterogeneous catalyst was utilized for the photoreduction of diluted CO 2 (0.998 % in N 2 ) at 25 8C, we found an average hydrocarbon production rate of 3.7 mL g À1 h À1 or 610 nmol cm À2 h À1 . The periodic modulation of the diameters of the nanotube arrays increased the surface area and improved the utilization of light while the bimetallic coating increased catalyst activity and specificity. Our version of a highly active CO 2 reduction system does not require reactant gases with high purities and could potentially be used to photocatalytically capture CO 2 directly from air or from flue gas...

Surface pressure (π)−molecular area (A) compression/expansion isotherms of N-octadecanoyl-l-alanine reflect homochiral discrimination behavior of the enantiomeric monolayer. FTIR studies indicate that carboxylic acid groups form out-of-plane ring dimers between two adjacent N-octadecanoyl-l-alanine molecules in monolayer LB films and that the long hydrocarbon chains in the film matrix take a biaxial orientation. The enantiomeric molecules assemble regularly and twist from neighbor to neighbor, thus giving rise to chirality of the aggregate in the two-dimensional condensed phase. Prior to the phase transition, the transformation of the triclinic subcell packing of the hydrocarbon chains into a hexagonal packing occurs. The variable-temperature infrared spectra of LB films provide powerful evidence for the formation of a hydrogen-bonded structure between chiral headgroups.

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Entropy measures have been extensively used to assess heart rate variability (HRV), a noninvasive marker of cardiovascular autonomic regulation. It is yet to be elucidated whether those entropy measures can sensitively respond to changes of autonomic balance and whether the responses, if there are any, are consistent across different entropy measures. Sixteen healthy subjects were enrolled in this study. Each subject undertook two 5-min ECG measurements, one in a resting seated position and another while walking on a treadmill at a regular speed of 5 km/h. For each subject, the two measurements were conducted in a randomized order and a 30-min rest was required between them. HRV time series were derived and were analyzed by eight entropy measures, i.e., approximate entropy (ApEn), corrected ApEn (cApEn), sample entropy (SampEn), fuzzy entropy without removing local trend (FuzzyEn-g), fuzzy entropy with local trend removal (FuzzyEn-l), permutation entropy (PermEn), conditional entropy (CE), and distribution entropy (DistEn). Compared to resting seated position, regular walking led to significantly reduced CE and DistEn (both p ≤ 0.006; Cohen's d = 0.9 for CE, d = 1.7 for DistEn), and increased PermEn (p < 0.0001; d = 1.9), while all these changes disappeared after performing a linear detrend or a wavelet detrend (<~0.03 Hz) on HRV. In addition, cApEn, SampEn, FuzzyEn-g, and FuzzyEn-l showed significant decreases during regular walking after linear detrending (all p < 0.006; 0.8 < d < 1), while a significantly increased ApEn (p < 0.0001; d = 1.9) and a significantly reduced cApEn (p = 0.0006; d = 0.8) were observed after wavelet detrending. To conclude, multiple entropy analyses should be performed to assess HRV in order for objective results and caution should be paid when drawing conclusions based on observations from a single measure. Besides, results from different studies will not be comparable unless it is clearly stated whether data have been detrended and the methods used for detrending have been specified.

A 17 step synthesis of 55, a late intermediate in Danishefsky's guanacastepene A synthesis, has been completed in 4% overall yield. Key features include the use of vinylmagnesium bromide in the Pd-catalyzed coupling with triflate 13 to give triene 16 without the formation of Heck products, a novel extension of the Stork-Jung vinylsilane Robinson annulation that provides tricyclic 2-hydroxymethylcyclohexenone 42 from 23b in four steps and 51% yield, the ability to obtain almost exclusively alpha'-alkylation of 35ba by the proper choice of protecting groups, and the ability to obtain the desired beta-alcohol selectively by reduction of keto alcohol 42 rather than keto ester 53.