Surface-Plasmon-Assisted Photoelectrochemical Reduction of CO2 and NO3− on Nanostructured Silver Electrodes

Electrochemical reduction of carbon dioxide (CO2) typically suffers from low selectivity and poor reaction rates that necessitate high overpotentials, which impede its possible application for CO2 capture, sequestration, or carbon-based fuel production. New strategies to address these issues include the utilization of photoexcited charge carriers to overcome activation barriers for reactions that produce desirable products. This study demonstrates surface-plasmon-enhanced photoelectrochemical reduction of CO2 and nitrate (NO3−) on silver nanostructured electrodes. The observed photocurrent likely originates from a resonant charge transfer between the photogenerated plasmonic hot electrons and the lowest unoccupied molecular orbital (MO) acceptor energy levels of adsorbed CO2, NO3−, or their reductive intermediates. The observed differences in the resonant effects at the Ag electrode with respect to electrode potential and photon energy for CO2 versus NO3− reduction suggest that plasmonic hot-carriers interact selectively with specific MO acceptor energy levels of adsorbed surface species such as CO2, NO3−, or their reductive intermediates. This unique plasmon-assisted charge generation and transfer mechanism can be used to increase yield, efficiency, and selectivity of various photoelectrochemical processes

Directing Selectivity of Electrochemical Carbon Dioxide Reduction Using Plasmonics

Catalysts for electrochemical carbon dioxide reduction in aqueous electrolytes suffer from high energy input requirements, competition with hydrogen evolution from water reduction, and low product selectivity. Theory suggests that plasmonic catalysts can be tuned to selectively lower the energy barrier for a specific reaction in a set of competitive reactions, but there has been little experimental evidence demonstrating plasmon-driven selectivity in complicated multielectron electrochemical processes. Here, the photoactivity at a plasmonically active silver thin film electrode at small cathodic potentials selectively generates carbon monoxide while simultaneously suppressing hydrogen production. At larger cathodic potentials, the photoactivity promotes production of methanol and formate. Methanol production is observed only under illumination, not in dark conditions. The preference of the plasmonic activity for carbon dioxide reduction over hydrogen evolution and the ability to tune plasmonic activity with voltage demonstrates that plasmonics provide a promising approach to promote complex electrochemical reactions over other competing reactions

Applying a new version of the Brazilian-Portuguese UPSIT smell test in Brazil

Standardized olfactory tests are now available to quantitatively assess disorders of olfaction. A Brazilian-Portuguese version of the University of Pennsylvania Smell Identification Test (UPSIT) is currently being developed specifically for the Brazilian population. The most recent Brazilian-Portuguese version of the UPSIT (UPSIT-Br2) was administered to 88 Brazilian subjects who had no history of neurological or otorhinolaryngological disease. UPSIT-Br2 scores decreased with age, were lower in men than in women, and were lower in subjects with lower income. The degree to which the poorer performance of subjects with lower socio-economic status reflects lack of familiarity with test items is not known. Although this version of the UPSIT provides a sensitive and useful test of smell function for the Brazilian population, a revision of some test items is needed to achieve comparable norms to those found using the North American UPSIT in the United States

Interdependent Pricing and Markup Behavior: An Empirical Analysis of GM, Ford and Chrysler

Our purpose in this paper is to develop and estimate a model of the US automobile industry that can be used to analyze the secular and cyclical strategic markup behavior and market structure of its three major domestic producers - - GM, Ford and Chrysler. The principal novelty in this paper is not such much in the underlying theory (we build on what Timothy Bresnahan has called the "new empirical industrial organization" literature), but rather in the actual empirical implementation of a multi-equation model sufficiently general to permit the testing of a variety of specific behavioral postulates associated with the interdependent strategic profit-maximizing behavior of GM, Ford and Chrysler. Using firm-specific annual data from 1959-83, we find that at usual levels of statistical significance, we cannot reject Cournot quantity-setting behavior, nor can we reject leader/follower quantity-setting behavior with GM as leader and Ford and Chrysler as followers; the parameter restrictions associated with leader/follower behavior are slightly more binding than those with Cournot, although the difference is not decisive. In terms of the cyclical analysis of market behavior, our most striking result is the great diversity of behavior we find among GM, Ford and Chrysler. Depending on which firm is being analyzed, there is support for the pro-cyclical "conventional wisdom" of markups (GM and Ford), as well as for the counter-cyclical "revisionist" literature (Chrysler). Diversity, rather than constancy and homogeneity, best characterizes firms in this industry.

An analytic solution to the Busemann-Petty problem on sections of convex bodies

We derive a formula connecting the derivatives of parallel section functions of an origin-symmetric star body in R^n with the Fourier transform of powers of the radial function of the body. A parallel section function (or (n-1)-dimensional X-ray) gives the ((n-1)-dimensional) volumes of all hyperplane sections of the body orthogonal to a given direction. This formula provides a new characterization of intersection bodies in R^n and leads to a unified analytic solution to the Busemann-Petty problem: Suppose that K and L are two origin-symmetric convex bodies in R^n such that the ((n-1)-dimensional) volume of each central hyperplane section of K is smaller than the volume of the corresponding section of L; is the (n-dimensional) volume of K smaller than the volume of L? In conjunction with earlier established connections between the Busemann-Petty problem, intersection bodies, and positive definite distributions, our formula shows that the answer to the problem depends on the behavior of the (n-2)-nd derivative of the parallel section functions. The affirmative answer to the Busemann-Petty problem for n\le 4 and the negative answer for n\ge 5 now follow from the fact that convexity controls the second derivatives, but does not control the derivatives of higher orders.Comment: 13 pages, published versio

Calibration of colour gradient bias in shear measurement using HST/CANDELS data

Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point-spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity for a broad band observation can lead to new subtle effects that could hitherto be ignored: the PSF of a galaxy is no longer uniquely defined and spatial variations in the colours of galaxies result in biases in the inferred lensing signal. Taking Euclid as a reference, we show that this colourgradient bias (CG bias) can be quantified with high accuracy using available multi-colour Hubble Space Telescope (HST) data. In particular we study how noise in the HST observations might impact such measurements and find this to be negligible. We determine the CG bias using HST observations in the F606W and F814W filters and observe a correlation with the colour, in line with expectations, whereas the dependence with redshift is weak. The biases for individual galaxies are generally well below 1%, which may be reduced further using morphological information from the Euclid data. Our results demonstrate that CG bias should not be ignored, but it is possible to determine its amplitude with sufficient precision, so that it will not significantly bias the weak lensing measurements using Euclid data

Synthesis of CoAl2O4 by double decomposition reaction between LiAlO2 and molten KCoCl3

Submicronic CoAl2O4 powders were prepared by double decomposition reaction between solid LiAlO2 and molten KCoCl3 at 500 ◦C for 24 h. The reaction mechanism involves the dissolution of LiAlO2 shifted by the precipitation of CoAl2O4 until complete transformation and the reaction leads to powders with a very homogeneous chemical composition. The powders obtained were mainly characterized by XRD, FTIR, ICP, X.EDS, electron microscopy and diffraction and diffuse reflexion. The blue pigments obtained exhibit a high thermic stability allowing their use for the colouring of ceramic tiles

Investigation of Canard Missile with Planar and Grid Fins by using CFD Tool

The aerodynamic coefficients and flow surrounding a canard missile design were predicted using viscous computational fluid dynamics simulation. The computations were performed at speeds between 1.5 and 3.0. High-speed flight is possible with canard deflection angles of 0 to 10 degrees, as well as planar and grid tail fins. The estimated aerodynamic coefficients were found to be astonishingly close to those obtained in the wind tunnel once data from the wind tunnel was analysed. It is possible that the flow visualisations produced by this work could lead to a better understanding of flow physics and the development of superior canard and tail fin designs for missiles and rockets among other things. Planar fins have a negative roll impact because of the pressure difference between the lowered fin and the canard trailing vortices. Grid tail fins improved the canards\u27 ability to roll at low supersonic speeds by increasing their rolling efficiency

Assessment of Mechanical Problems for Centrifugal Pumps in Eastern Uttar Pradesh, India

Centrifugal pumps are vital property of the agriculture sector. A good quality pump can assure uninterrupted water supply to irrigate crops. The consumer of agriculture sector is largely illiterate and shortcoming of the pumps is faced by farmers in the terms of wastage of money. The study has carried out to grow awareness about the technique among the farmers. In such cases reliable functioning of the pump is an absolute necessity. The major objective of this paper is the analysis of the component life and frequency of occurrence of problem in a centrifugal pump. A survey was conducted among the farmers of tube well irrigated areas and subsequently analyzed. It was found that frequency of occurrence of leakage and excessive noise are 3.17 and 3.11 years which is the most frequent shortcoming found under study. It was also found that the mean life of centrifugal pump components i.e. Bearing, Packing, Impeller, shaft and casing was found as 3.56 , 3.18 , 3.61, 4.20 and 4.64 years respectively. The package of seal has longest life for the operation of centrifugal pump. For the frequency of occurrence of these problems, four the category scale has also chosen. Value 1 refers to always occurs, 2 most frequent occurs, 3 occasionally occurs, 4 – rarely occurs. Under the study a centrifugal pump for irrigating crop has treated as vital input, which is also a key factor in boosting productivity, for the national development and food security