bluuebunny/crossref_metadata_2025_split huggingface dataset:
An integrated modelling framework of catchment‐scale ecohydrological processes: 2. The role of water subsidy by overland flow on vegetation dynamics in a semi‐arid catchment
Authors: Niu Guo‐Yue , Troch Peter A. , Paniconi Claudio , Scott Russell L. , Durcik Matej , Zeng Xubin , Huxman Travis , Goodrich David , Pelletier Jon 
Published: June 2013

ABSTRACTIn water‐limited regions, surface water and carbon fluxes are strongly controlled by soil water availability, which may be highly variable at very small spatial scales (e.g. metres) because of variations in terrain, soils, and vegetation conditions and to processes of water redistribution along hillslopes. This second of a two‐part paper first evaluates the performance of a newly developed ecohydrological model over a small semi‐arid experimental catchment (7·92 ha) in southeastern Arizona. Secondly, it investigates the effects of soil properties on water subsidy resulting from lateral overland flow re‐infiltration and on overall ecohydrological response.With optimized parameters, the model shows a higher ability to simulate surface energy and water fluxes than CO2 fluxes at all temporal scales. The model simulates observed CO2 fluxes fairly well at diurnal scales during the main growing seasons and the interannual variability of these fluxes in response to soil moisture variations from drought years to wet years. However, the model reproduces less well carbon assimilation in spring and positive CO2 flux pulses following early monsoon rain events, suggesting a need for further development of the model's representations of multiple plant species and soil carbon decomposition. The model simulates soil moisture at 5 cm much better than at 15 cm mainly because of heterogeneous soil properties. Through five numerical experiments with varying saturated hydraulic conductivity values, it is revealed that the discharge at the outlet of this semi‐arid catchment is essentially attributed to lateral overland flow that is generated mainly by infiltration‐excess runoff. Subsurface flow plays a minor role in this semi‐arid catchment with a very deep groundwater table (>100 m). The model produces wetter soils in lowland areas along stream rills and channels through re‐infiltration of lateral overland flow. This water subsidy provides plants with favourable conditions to produce more leaves, CO2, and ET fluxes in lowland areas. Re‐infiltration of overland flow over complex terrain may play a role in buffering climatic impacts in a warming climate with fewer but more intense rainfall events in the Southwestern United States. Copyright © 2013 John Wiley & Sons, Ltd.
Application of a Partial Least Squares Regression for the Determination of Nanomolar Concentrations of Scandium in the Presence of Nickel by Adsorptive Stripping Voltammetry
Authors: Jakubowska Małgorzata , Piech Robert , Górski Łukasz 
Published: June 2013

AbstractThis paper presents the methodology of a very sensitive determination of scandium in excess of nickel by adsorptive stripping voltammetry on a mercury film electrode and PLS regression. A calibration set consisting of binary mixtures containing 5, 15, 25, 35 or 45×10−9 M Sc(III) and simultaneously 0.5–50×10−7 M of Ni(II) was used to develop the chemometric PLS calibrations. An external set containing synthetic mixtures of 10, 20, 30, 40×10−9 M Sc(III) and the same Ni(II) concentration as mentioned above was used to validate the model and evaluate predictive ability. The application of data pretreatment techniques involving baseline correction, smoothing, range‐scaling, mean‐centering and their influence on the PLS model complexity, were also investigated. In the effect, the model for Sc(III), including 6 latent variables, was constructed. The model fulfills validation criteria and is characterized by a good prediction ability (majority of the prediction errors are lower than 10%). This work shows significant progress in the development of a very sensitive analytical technique for the determination of scandium in the presence of different concentrations of nickel by application of multivariate calibration tools.
High‐resolution methods for preserving the sum of mass fractions: improved χ‐scheme and an alternative
Authors: Syamlal Madhava , Benyahia Sofiane 
Published: June 2013

SUMMARYWhen high resolution convection schemes are used for discretizing chemical species mass balance equations, the mass fractions are not guaranteed to add to one. We show that a proposed remedy called χ —scheme (Darwish and Moukalled, Comput. Methods Appl. Mech. Engrg. 192 (2003): 1711) will degrade to a diffusive first‐order scheme when a chemical species vanishes from the mixture, for example, because of chemical reactions. We propose an improvement to the χ ‐scheme to overcome this problem. Furthermore, a computationally efficient alternative scheme is proposed and evaluated with several examples, to quantify the improvements in the accuracy and the computational time. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Investigation of the Direct Methanol Fuel Cell with Novel Assembly Method
Authors: Yuan Z. Y. , Zhang Y. F. , Fu W. T. , Li Z. P. , Liu X. W. 
Published: June 2013

AbstractAssembly pressure compresses the under part of the gas diffusion layer, and the inhomogeneous compression can cause performance variation of the direct methanol fuel cell. Compared with the cell with traditional assembly method using bolts at the corner of plates, the cell with a novel assembly method uniforming the pressure is designed, fabricated, and tested in this paper. First, a three‐dimensional model is developed to simulate the pressure distribution with different assembly patterns. Then, a multi‐physics simulation including methanol mass transport, methanol diffusion, and electron transport is conduced. The modeling results reveal that the novel assembly method can ensure the flatness of the membrane electrode when compared with the traditional method. The overall performance first increases and then decreases with the increase of assembly pressure, and the optimal pressure is 1.5 MPa. Additionally, the cell with both assembly methods are fabricated and tested under optimal condition, and there are only <8% discrepancy between the experimental results and simulation; Influences of cell efficiency patterned with two assembly methods are also studied.
Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes
Authors: Cleemann L. N. , Buazar F. , Li Q. , Jensen J. O. , Pan C. , Steenberg T. , Dai S. , Bjerrum N. J. 
Published: June 2013

AbstractDegradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little contribution of the membrane degradation to the performance losses during the potential cycling tests. As the major mechanism of the fuel cell performance degradation, the electrochemical active area of the cathodic catalysts showed a steady decrease in the cyclic voltammetric measurements, which was also confirmed by the post TEM and XRD analysis. A strong dependence of the fuel cell performance degradation on the catalyst supports was observed. Graphitization of the carbon blacks improved the stability and catalyst durability though at the expense of a significant decrease in the specific surface area. Multi‐walled carbon nanotubes as catalyst supports showed further significant improvement in the catalyst and fuel cell durability.
Operation of the Alkaline Direct Formate Fuel Cell in the Absence of Added Hydroxide
Authors: Nguyen T. Q. , Bartrom A. M. , Tran K. , Haan J. L. 
Published: June 2013

AbstractThe direct formate fuel cell (DFFC) has recently been demonstrated as a viable alkaline direct liquid fuel cell (DLFC) that does not require addition of hydroxide to the fuel stream for operation. In this work, we report that the DFFC can produce significant power at low temperatures without added hydroxide, especially when compared with other alkaline DLFCs powered by alcohols. Using oxygen at the cathode, the DFFC powered by 1 M HCOOK achieves a maximum power density of 106 mW cm–2 at 50 °C and 64 mW cm–2 at 23 °C. Using air at the cathode, the same DFFC achieves a maximum power density of 76 mW cm–2 at 50 °C and 27 mW cm–2 at 23 °C. These power densities were achieved without addition of hydroxide to the fuel stream. Constant current operation demonstrates that the maximum power density can be maintained at least for several hours of operation. Finally, we use electrochemical analysis to demonstrate that the formate oxidation reaction is not dependent on pH between 9 and 14, which permits the use of formate fuel without added hydroxide in the DFFC. An alkaline DLFC that does not require added hydroxide is promising for safe and practical operation.
Exergoeconomic Analysis of a Residential Hybrid PV‐Fuel Cell‐Battery System
Authors: Hosseini M. , Dincer I. , Rosen M. A. 
Published: June 2013

AbstractA residential photovoltaic (PV)‐based hydrogen fuel cell (FC) system is analyzed using exergoeconomic methods, and its monthly performance is investigated. Mathematical models for predicting the power outputs of the PV and FC systems are presented. The results reported include the PV output and the shares attributable to the battery and the SOFC in supplying the electrical demand. Moreover, to study the performance of the hybrid system in supplying the daily demand, results are presented for two typical days in summer and winter. An exergoeconomic analysis is performed to determine the electricity unit cost over the system lifetime. The PV‐electrolyzer system is not able to produce a sufficient amount of hydrogen during winter days, so seasonal hydrogen storage is required to feed the FC. Power penetrations of the PV and the battery systems are at maxima during the summer months, while the penetration of the FC system reaches 67% in January and December. Due to its low efficiency (16%), the maximum exergy destruction occurs in the PV modules (86%). The unit cost of electricity varies on a monthly basis, reaching a minimum of 0.26 $ kWh–1 in July and a maximum of 1.8 $ kWh–1 in January and December.
ANALYSIS OF TRACING ABILITY OF DIFFERENT SIZED PARTICLES IN DRIP IRRIGATION EMITTERS WITH COMPUTATIONAL FLUID DYNAMICS
Authors: Li Yunkai , Liu Haisheng , Yang Peiling , Wu Dan 
Published: June 2013

ABSTRACTThe tracing ability of particles in the flow path is the key to digital particle image velocimetry (DPIV) testing and clogging control in drip irrigation emitters. Six different kinds of particles with respective diameters of 0.01, 0.02, 0.04, 0.05, 0.06 and 0.08 mm were considered, and the tracing ability was carried out by using the computational fluid dynamics (CFD) turbulence simulation method. Results showed that standard k‐ε model could well describe the transportation process of particles in drip irrigation emitters in terms of precision, applicable extensibility and computational expense. Clogging most likely occurred in the corner of the whole flow path of the drip irrigation emitter region, sections 1 and 8 plus sections 4 and 5. The tracing ability of the particles of 0.01 mm diameter was good enough to be used for a single‐phase test. And for a two‐phase test, diameters of the particles should be more than 0.04 mm. Copyright © 2013 John Wiley & Sons, Ltd.
Preparation of Ce‐doped TiO2 Hollow Fibers and Their Photocatalytic Degradation Properties for Dye Compound
Authors: Shi Zhongliang , Zhou Mingtao , Zheng Dongsong , Liu Hao , Yao Shuhua 
Published: June 2013

AbstractCerium‐doped titanium dioxide (TiO2) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)‐doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), BET surface area, and UV‐vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO2 fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV‐vis diffuse absorption spectroscopy examinations, Ce‐doping restrained the growth of grain size and extended the photoabsorption edge of TiO2 hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO2 under UV and visible light, and the amount of Ce‐doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce‐doped TiO2 fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO2 may hopefully become a low‐energy consuming, high activity and green environmentally friendly catalytic material.
Luminescence and Spectroscopic Studies of (Y0.99Ce0.01)3OF3S2: A New Orange Yellow‐emitting Oxyfluorosulfide Phosphor for LEDs
Authors: Chen Shing‐Nian , Chen Teng‐Ming 
Published: June 2013

AbstractA new Ce3+‐doped oxyfluorosulfide phosphor, Y3OF3S2:Ce33+ has been investigated as a new candidate for potential application in phosphor‐converted light emitting diodes (pc‐LEDs). The synthesized Y3OF3S2:Ce33+ was characterized by powder X‐ray diffraction and various spectroscopic techniques. Y3OF3S2:Ce33+ can be excited by wide‐range (250‐400 nm) radiation and shows yellow‐orange broadband emission peaking at 610 nm with a quantum efficiency of 40%. These results indicate it may serve as a promising phosphor in near‐UV pc‐LEDs.
Enhancement of pollutants removal from real sewage by embedding microbial fuel cell in anaerobic–anoxic–oxic wastewater treatment process
Authors: Xie Beizhen , Dong Wenbo , Liu Bojie , Liu Hong 
Published: June 2013

AbstractBACKGROUNDDeveloping an economical biological nitrogen and phosphorus removal technology with high efficiency has become a research priority in current sewage treatment procedures. In order to solve the problems within the anaerobic–anoxic–oxic (A2/O) process, including substrates competition and high energy consumption, a microbial fuel cell (MFC) was embedded in the A2/O process to enhance the efficiencies of removal of nitrogen and phosphorus, along with electricity production.RESULTSThree A2/O reactors, one with an embedded MFC, were set up, and nitrogen and phosphorus removal efficiencies and electricity generation were investigated. At the stage of stable operation, the chemical oxygen demand, total nitrogen and total phosphorus removal efficiencies of the MFC‐A2/O reactor, compared with the control, were increased by 15.9%, 9.3% and 1.4% on average, respectively. The average output power density of the MFC was 14.3 ± 1.4 mW m−3 and the internal resistance was 6000 Ω. Grey relational analysis was applied to study the most significant operational parameter of the A2/O process affecting electricity production of the MFC.CONCLUSIONSThis research proved that nitrogen and phosphorus removal efficiency could be improved by embedding an MFC in the A2/O process. In addition, the MFC‐A2/O reactor can generate electricity continuously. © 2013 Society of Chemical Industry
Suppression of methanogenic activity in anaerobic granular biomass for hydrogen production
Authors: Hernández‐Mendoza Christian E. , Buitrón Germán 
Published: June 2013

AbstractBACKGROUNDSeveral pretreatment methods at lab‐scale have been developed to inactivate methane‐producing and hydrogen‐consuming microorganisms. The need to obtain a hydrogen‐producing inoculum by a more practical method is still necessary. The objective of this study was to evaluate the adaptation of anaerobic granules to suppress the methanogenic activity for hydrogen production.RESULTSPreliminary tests in discontinuous operation indicated that methanogenic bacteria were hardly suppressed. The continuous adaptation of the granules, at pH of 4.5 and HRT of 5.5 h, produced hydrogen and successfully suppressed the methanogenic activity. An even distribution of β‐polysaccharides and cells was observed when the adapted granules were stained with fluorescent molecular tags. The reactor productivity was 71 ± 6 mL‐H2 Lreactor−1 h−1 with a yield of 2.6 ± 0.2 mol H2 mol–1 glucose.CONCLUSIONHydrogen was produced from methanogenic granules. The continuous strategy successfully suppressed the methanogenic activity of the seeded granules and the hydrogen production was stable. The high yield and even distribution of cells suggests that the continuous adaptation generated a more active biomass due to an improved mass transfer present in the process. © 2013 Society of Chemical Industry
Waste Nitrogen Metabolism and Excretion in Zebrafish Embryos: Effects of Light, Ammonia, and Nicotinamide
Authors: BUCKING CAROL , LEMOINE CHRISTOPHE M.R. , WALSH PATRICK J. 
Published: June 2013

ABSTRACTBony fish primarily excrete ammonia as adults however the persistence of urea cycle genes may reflect a beneficial role for urea production during embryonic stages in protecting the embryo from toxic effects of ammonia produced from a highly nitrogenous yolk. This study aimed to examine the dynamic scope for changes in rates of urea synthesis and excretion in one such species (zebrafish, Danio rerio) by manipulating the intrinsic developmental rate (by alteration of light:dark cycles), as well as by direct chemical manipulation via ammonia injection (to potentially activate urea production) and nicotinamide exposure (to potentially inhibit urea production). Continuous dark exposure delayed development in embryos as evidenced by delayed appearance of hallmark anatomical features (heartbeat, eye pigmentation, body pigmentation, lateral line, fin buds) at 30 and 48 hr post‐fertilization, as well by a lower hatching rate compared to embryos reared in continuous light. Both ammonia and urea excretion were similarly effected and were generally higher in embryos continuously exposed to light. Ammonia injection resulted in significant increases (up to fourfold) of urea N excretion and no changes to ammonia excretion rates along with modest increases in yolk ammonia content during 2–6 hr post‐injection. Nicotinamide (an inhibitor of urea synthesis in mammals) reduced the ammonia‐induced increase in urea excretion and led to retention of ammonia in the yolk and body of the embryo. Our results indicate that there is a relatively rapid and large scope for increases in urea production/excretion rates in developing embryos. Potential mechanisms for these increases are discussed. J. Exp. Zool. 319A: 391–403, 2013. © 2013 Wiley Periodicals, Inc.
Concealed Quaternary strike‐slip fault resolved with airborne lidar and seismic reflection: The Grizzly Valley fault system, northern Walker Lane, California
Authors: Gold Ryan D. , Stephenson William J. , Odum Jack K. , Briggs Richard W. , Crone Anthony J. , Angster Stephen J. 
Published: June 2013

AbstractThe Grizzly Valley fault system (GVFS) strikes northwestward across Sierra Valley, a low‐relief basin situated within a network of active dextral slip faults in the northern Walker Lane, California. Quaternary motion along the Grizzly Valley fault system has not been previously documented. We used high‐resolution (0.25 m) airborne lidar data in combination with high‐resolution,Pwave, seismic reflection imaging to evaluate Quaternary deformation associated with the GVFS. We identified suspected tectonic lineaments using the lidar data and collected seismic reflection data along six profiles across the lineaments. The seismic reflection images reveal a deformed basal marker that we interpret to be the top of Tertiary volcanic rocks overlain by a 120–450 m thick suite of subhorizontal reflectors that we interpret to be Plio‐Pleistocene lacustrine deposits. Three profiles image features that we interpret to be the principal active trace of the GVFS, which is a steeply dipping fault zone that vertically offsets the volcanic rocks and the lacustrine basin fill. These data suggest that the GVFS may have been active in latest Quaternary time because (1) the lidar data show subtle surficial geomorphic features that are typical of youthful faulting, including a topographic lineament marked by an ~1 m high ridge composed of discontinuous, left‐stepping lobes, and (2) the seismic profiles demonstrate shallow faulting of the lacustrine strata that coincides with the left‐stepping ridge. This investigation illustrates the potential for unidentified, low‐rate, strike‐slip faults in basins and emphasizes the value of high‐resolution topographic data and subsurface imaging as a means of identifying these structures.
On the inclusion of Limb Infrared Monitor of the Stratosphere version 6 ozone in a data assimilation system
Authors: Remsberg E. , Natarajan M. , Fairlie T. D. , Wargan K. , Pawson S. , Coy L. , Lingenfelser G. , Kim G. 
Published: June 2013

AbstractVersion 6 ozone profiles for 1978–1979 from the Limb Infrared Monitor of the Stratosphere experiment on the NIMBUS 7 satellite (or LIMS v6) are assimilated into an updated version of the GEOS‐5 model of NASA. First, an assimilation study is carried out using GEOS‐5 version 7.2 (v7.2) and solar backscatter ultraviolet (SBUV) version 8.6 ozone profiles. Then, a second study is conducted that ingests both the LIMS and SBUV ozone, as weighted by their estimated absolute error vectors. Ozone from this second study compares well with independent observations from the Stratospheric Aerosol and Gas Experiment (SAGE I) and from the time series of ozonesonde data at Hohenpeissenberg and at Wallops Island. Assimilation of the LIMS data gives improved ozone distributions in the upper stratosphere (pressure < 5 hPa) and in the polar night region—the latter where solar backscatter ultraviolet (SBUV) is not observed. The LIMS ozone leads to improved total column ozone analyses in winter/spring outside of the tropics, based on independent comparisons with total ozone from the Total Ozone Mapping Spectrometer. The LIMS ozone also adds information in the tropics on coherent structural features at 20–30 hPa, related to the phase transition of the quasi‐biennial oscillation wind field. It is affirmed that the process of data assimilation represents a cost‐effective way of characterizing new and/or reprocessed satellite ozone data sets. It is concluded that the GEOS‐5 v7.2 model with the addition of the LIMS data can improve analyses of ozone in 1978–1979.