1,485 research outputs found
Effects of ultrasound on electrochemical oxidation mechanisms of p-substituted phenols at BDD and PbO2 anodes
The effects of low-frequency (40 kHz) ultrasound are investigated with regard to the effectiveness and mechanisms of electrochemical oxidation of p-substituted phenols (p-nitrophenol, p-hydroxybenzaldehyde, phenol, p-cresol, and p-methoxyphenol) at BDD (boron-doped diamond) and PbO2 anodes. Although ultrasound improved the disappearance rates of p-substituted phenols at both the BDD and PbO2 anodes, the degree of enhancement varied according to the type of p-substituted phenol and type of anode under consideration. At the BDD anode, the % Increase values were in the range 73-83% for p-substituted phenol disappearance and in the range 60-70% for COD removal. However, at the PbO2 anode, the corresponding %Increase values were in the range 50-70% for disappearance of p-substituted phenols and only 5-25% for COD removal, much lower values than obtained at the BDD anode. Further investigations on the influence of ultrasound on the electrochemical oxidation mechanisms at BDD and PbO2 anodes revealed that the different increase extent were due to the specialized electrochemical oxidation mechanisms at these two anodes. The hydroxyl radicals were mainly free at the BDD electrodes with a larger reaction zone, but adsorbed at the PbO2 electrodes with a smaller reaction zone. Therefore, the enhancement due to ultrasound was greater at the BDD anode than at the PbO2 anode. (C) 2010 Elsevier Ltd. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000280422800007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701ElectrochemistrySCI(E)EI21ARTICLE205569-55755
Effects of electrostatic interaction on clustering and collision of bidispersed inertial particles in homogeneous and isotropic turbulence
In sandstorms and thunderclouds, turbulence-induced collisions between solid
particles and ice crystals lead to inevitable triboelectrification. The charge
segregation is usually size-dependent, with small particles charged negatively
and large particles charged positively. In this work, we perform numerical
simulations to study the influence of charge segregation on the dynamics of
bidispersed inertial particles in turbulence. Direct numerical simulations of
homogeneous isotropic turbulence are performed with the Taylor Reynolds number
, while particles are subjected to both
electrostatic interactions and fluid drag, with Stokes number of 1 and 10 for
small and large particles, respectively. Coulomb repulsion/attraction are shown
to effectively inhibit/enhance particle clustering within a short range.
Besides, the mean relative velocity between same-size particles is found to
rise as the particle charge increases because of the exclusion of low-velocity
pairs, while the relative velocity between different-size particles is almost
unaffected, emphasizing the dominant roles of differential inertia. The mean
Coulomb-turbulence parameter, , is then defined to characterize
the competition between the Coulomb potential energy and the mean relative
kinetic energy. In addition, a model is proposed to quantify the rate at which
charged particles approach each other and captures the transition of the
particle relative motion from the turbulence-dominated regime to the
electrostatic-dominated regime. Finally, the probability distribution function
of the approaching rate between particle pairs are examined, and its dependence
on the Coulomb force is further discussed using the extended Coulomb-turbulence
parameter.Comment: 23 pages, 8 figure
Remote Sensing Spatiotemporal Assessment of Nitrogen Concentrations in Tampa Bay, Florida due to a Drought
A long-term low nitrogen to phosphorus (N:P) ratio in the Tampa Bay, Florida, estuary system suggests that nitrogen is more limiting than phosphorus. However, south Florida suffered from a drought around 2007, and the reduction in runoff flowing into the bay affected local ecosystem dynamics. This study presents a remote sensing study to retrieve spatiotemporal patterns of total nitrogen (TN) concentrations in Tampa Bay under drought impacts through the integration of Moderate Resolution Imaging Spectroradiometer (MODIS) images and a genetic programming (GP) model. Research findings show that the drought impact on TN in Tampa Bay is both a seasonal and yearly phenomenon. Without the presence of ocean water intrusion, the whole bay would show a relatively uniform TN distribution during the drought period until the flow input from rivers returned to normal. Based on yearly comparisons, temperature could be the limiting factor on the plankton growth in Tampa Bay. To further substantiate the credibility of a nutrient estimation algorithm, a k-means clustering analysis was conducted to demonstrate sea-bay-land interactions among ebbs, tides, and river discharges. The seasonal cluster distribution in 2007 is generally consistent with the conventional segments division of Tampa Bay
(Azido-κN)[6-methoxy-2-(2-pyridylmethyliminomethyl)phenolato-κ3 N,N′,O 1]copper(II)
The title compound, [Cu(C14H13N2O2)(N3)], is a monomeric neutral complex with one unsymmetrical 6-methoxy-2-(2-pyridylmethyliminomethyl)phenolate Schiff base ligand and one azide ligand. The molecules are connected by a combination of two π–π interactions [centroid–centroid distances 3.359 (3) and 3.378 (2) Å] and one C—H⋯N hydrogen bond into a two-dimensional supramolecular network structure
Modelling Fertilizer Use in Relation to Farmers’ Household Characteristics in Three Gorges Reservoir Area, China
Non-point source pollution from excessive use of fertilizers in agriculture is a major cause of the eutrophication problem in China. Understanding farmers’ decision-making concerning fertilization and identifying the influencing factors in this process are key to tackling overfertilization and related pollution issues. This paper reports a study on modelling decisions about fertilizer use based on data collected from 200 farmer households in the Three Gorges Reservoir area of China, using a well-fitted artificial neural network (ANN) with incorporated variance-based sensitivity analysis. The rate of fertilizer use estimated from the model is in good agreement with observed data. The model is further validated and tested by comparing the simulated and observed values. Results show that the model is able to identify the influencing factors and their interactions causing the variation in fertilizer use and to help pinpoint the underlying reasons. It is found that the farmers’ fertilization behavior is greatly affected by the area of cultivated land, followed by the interaction among farmers’ education level, annual income, and awareness of the importance of environmental protection. Future land consolidation is one of several ways to achieve more sustainable fertilization strategies
Modeling of a combined CH<sub>4</sub>-assisted solid oxide co-electrolysis and Fischer-Tropsch synthesis system for low-carbon fuel production
10th International Conference on Applied Energy, ICAE 2018, Hong Kong, 22-25 August 2018201906 bcmaVersion of RecordPublishe
Remote Sensing Spatiotemporal Assessment of Nitrogen Concentrations in Tampa Bay, Florida due to a Drought
A long-term low nitrogen to phosphorus (N:P) ratio in the Tampa Bay, Florida, estuary system suggests that nitrogen is more limiting than phosphorus. However, south Florida suffered from a drought around 2007, and the reduction in runoff flowing into the bay affected local ecosystem dynamics. This study presents a remote sensing study to retrieve spatiotemporal patterns of total nitrogen (TN) concentrations in Tampa Bay under drought impacts through the integration of Moderate Resolution Imaging Spectroradiometer (MODIS) images and a genetic programming (GP) model. Research findings show that the drought impact on TN in Tampa Bay is both a seasonal and yearly phenomenon. Without the presence of ocean water intrusion, the whole bay would show a relatively uniform TN distribution during the drought period until the flow input from rivers returned to normal. Based on yearly comparisons, temperature could be the limiting factor on the plankton growth in Tampa Bay. To further substantiate the credibility of a nutrient estimation algorithm, a k-means clustering analysis was conducted to demonstrate sea-bay-land interactions among ebbs, tides, and river discharges. The seasonal cluster distribution in 2007 is generally consistent with the conventional segments division of Tampa Bay
Tetraaquabis(2-methylbenzimidazolium-1,3-diacetato-κO)zinc(II) tetrahydrate
The asymmetric unit of the title compound, [Zn(C12H11N2O4)2(H2O)4]·4H2O, contains one-half of the complex molecule and two uncoordinated water molecules. The four water O atoms in the equatorial plane around the ZnII centre ( symmetry) form a distorted square-planar arrangement, while the distorted octahedral coordination geometry is completed by the O atoms of the zwitterionic 2-methylbenzimidazolium-1,3-diacetate ligands in the axial positions. The benzimidazole ring system is planar, with a maximum deviation of 0.041 (3) Å. Intramolecular O—H⋯O hydrogen bonding results in the formation of a non-planar six-membered ring. In the crystal structure, strong intra- and intermolecular O—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π contacts between benzimidazole rings [centroid–centroid distance = 3.899 (1) Å] may further stabilize the structure
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