378 research outputs found
A new conducting polymer with exceptional visible-light photocatalytic activity derived from varbituric acid polycondensation
Abstract A novel covalent, metal-free, photocatalytic material is prepared by thermal polymerization of barbituric acid (BA). The structure of the photocatalyst is analyzed by using scanning electron microscopy, X-ray diffraction, and infrared, UV?visible, and 1H solution and 13C solid-state NMR spectroscopy. The photodegradation efficiency of BA thermally polymerized at different temperatures is tested by photocatalytic degradation of aquatic rhodamine B (RhB) dye under visible-light irradiation. It is shown that heating BA at an optimized temperature of 300 °C, that is, still in the range that polymer-like polycondensation takes place, results in a photocatalyst that can remove RhB with 96% photodegradation efficiency after 70 min exposure to visible light. The polycondensation reaction of BA is identified to process through precipitation of trimer units as primary building blocks. Reference experiments such as addition of scavengers and saturation with oxygen are studied to understand the photodegradation process. It is shown that the presence of triethanolamine, and excess of oxygen and p-benzoquinone in the solution of RhB and photocatalyst (BA300) is not beneficial, but decreases the photodegradation efficiency
Flattening of the Phillips Curve and the Role of Oil Price: An Unobserved Components Model for the USA and Australia
We use the unobserved components model of Harvey (1989 and 2011) to estimate the Phillips curve (PC) for the USA and Australia, by augmenting it with oil prices. We found that the level coefficient of inflation and the coefficient of demand pressure have declined and contributed to the flattening of the Phillips curve. But the coefficient of oil prices has increased and has partly offset these effects. Therefore, oil prices are likely to play a significant role in future inflation rates.
Estudio etnobotánico de áreas del noroeste de la provincia de Isfahan, Iran
Iran is one of the countries which enormously used medicinal plants from the ancient times. In this study, we documented the ethnobotanical data of Golpayegan, and Shahin Shahr and Meymeh counties (Isfahan province) for the first time in Iran. Field study and plant collecting were done in different seasons in 2016–2017. Ethnobotanical data were analyzed using information of questionnaires gained from 27 inhabitants. Totally, 48 plants of 24 families were recorded from studied areas. Asteraceae (36%) and Lamiaceae (23%) are those containing the biggest numbers of cited plants. Moreover, leaves (45.83%) and seeds (18.75%) were the most used parts. This study indicated the importance of useful plants of studied areas and the necessity of doing this kind of research on other parts of country in order to preserve this valuable information of local inhabitants.Irán es un país que ha utilizado de manera destacada las plantas medicinales desde la antigüedad. En este estudio, documentamos los datos etnobotánicos de los condados de Golpayegan, Shahin Shahr y Meymeh (provincia de Isfahán) por primera vez en Irán. El estudio de campo y la recolección de plantas se realizaron en diferentes temporadas en 2016 y 2017. Los datos etnobotánicos se analizaron utilizando información proveniente de cuestionarios realizados a 27 informantes. En total, se registraron 48 plantas de 24 familias de las áreas estudiadas. Las familias Asteraceae (36%) y Lamiaceae (23%) son las que contienen un mayor número de plantas citadas. Las hojas (45,83%) y las semillas (18,75%) son las partes de planta más utilizadas. Este estudio indica la importancia de las plantas útiles de las áreas estudiadas y la necesidad de realizar este tipo de investigación en otras partes del país con el fin de preservar esta valiosa información de los habitantes locales
Scour at partially blocked box-culverts under steady flow
© 2016, Thomas Telford Services Ltd. All rights reserved. Culverts are built at locations where a waterway crosses a road or railway and creates a limitation to flow passage. Furthermore, blockage commonly occurs during flood events with accumulation of debris at the culvert inlet. The inlet blockage changes the flow structure at the outlet and may result in culvert failure. Despite this, the impacts of blockage on culvert hydraulics and downstream waterways have not received consideration in the literature. The purpose of this paper is to mitigate this deficiency by reporting on an investigation into scouring at the outlet of partially blocked culverts. Experimental tests were conducted under steady flow to investigate a relationship between the maximum scour depth, blockage ratio of the culvert and the flow characteristics. Both non-blocked and partially blocked conditions were considered. Consideration of the results obtained showed that the scoured area and maximum scour depth increased with partially blocked culverts conditions compared with equivalent non-blocked culverts
Location of the maximum scouring depth at the outlet of partially-blocked and non-blocked box culvert
Among various hydraulic structures, culvert is the most likely one which usually blocks by the debris that are carrying by flow during large flood events. The size of the structure and its location where a waterway crosses a road or railway increases the possibility of clogging. The blockage of culvert accelerates bed scouring at the outlet hence affects bed scouring profile. This leads to increase the risk of culvert collapsed and produce different kinds of damages to the society. The present study concerns the effect of upstream blockage on the scouring profile at the outlet of a box culvert. Therefore, the experimental program was designed to investigate the relationship between the scouring geometry and blockage ratio. The experimental tests were carried out under non-blocked and partially blocked conditions. The sediment material used in this study was uniform non-cohesive sand material. Results showed that the scouring bed profile is different in partially blocked condition when compared to the non-blocked condition. Additionally it was found that the maximum scouring depth in a partially blocked culvert occurred at a distance very close to the outlet of the box culvert. © 2014 Taylor & Francis Group, London
Probabilistic Tensor Decomposition of Neural Population Spiking Activity
The firing of neural populations is coordinated across cells, in time, and across experimental conditions or repeated experimental trials, and so a full understanding of the computational significance of neural responses must be based on a separation of these different contributions to structured activity. Tensor decomposition is an approach to untangling the influence of multiple factors in data that is common in many fields. However, despite some recent interest in neuroscience, wider applicability of the approach is hampered by the lack of a full probabilistic treatment allowing principled inference of a decomposition from non-Gaussian spike-count data. Here, we extend the Polya-Gamma (PG) augmentation, previously used in sampling-based Bayesian inference, to implement scalable variational inference in non-conjugate spike-count models. Using this new approach, we develop techniques related to automatic relevance determination to infer the most appropriate tensor rank, as well as to incorporate priors based on known brain anatomy such as the segregation of cell response properties by brain area. We apply the model to neural recordings taken under conditions of visual-vestibular sensory integration, revealing how the encoding of self- and visual-motion signals is modulated by the sensory information available to the animal
On the sample size dependence of the critical current density in MgB superconductors
Sample size dependent critical current density has been observed in magnesium
diboride superconductors. At high fields, larger samples provide higher
critical current densities, while at low fields, larger samples give rise to
lower critical current densities. The explanation for this surprising result is
proposed in this study based on the electric field generated in the
superconductors. The dependence of the current density on the sample size has
been derived as a power law ( is the factor
characterizing curve ). This dependence provides one with
a new method to derive the factor and can also be used to determine the
dependence of the activation energy on the current density.Comment: Revtex, 4 pages, 5 figure
Multisensory coding of angular head velocity in the retrosplenial cortex
To successfully navigate the environment, animals depend on their ability to continuously track their heading direction and speed. Neurons that encode angular head velocity (AHV) are fundamental to this process, yet the contribution of various motion signals to AHV coding in the cortex remains elusive. By performing chronic single-unit recordings in the retrosplenial cortex (RSP) of the mouse and tracking the activity of individual AHV cells between freely moving and head-restrained conditions, we find that vestibular inputs dominate AHV signaling. Moreover, the addition of visual inputs onto these neurons increases the gain and signal-to-noise ratio of their tuning during active exploration. Psychophysical experiments and neural decoding further reveal that vestibular-visual integration increases the perceptual accuracy of angular self-motion and the fidelity of its representation by RSP ensembles. We conclude that while cortical AHV coding requires vestibular input, where possible, it also uses vision to optimize heading estimation during navigation
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