bluuebunny/crossref_metadata_2025_split huggingface dataset:
Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
Authors: Childress Evan S. , McIntyre Peter B. 
Published: July 2016

AbstractMigratory animals can have profound impacts on ecosystem structure and function. In streams, salmon are well known for their contrasting influences on primary productivity through nutrient delivery, which enhances potential productivity, and substrate disturbance during nest building, which reduces algal biomass and primary production. However, most migratory fish species neither disturb the substrate significantly nor die en masse after spawning, hence their influence on ecosystems may differ from that observed in salmon streams. To determine the influence of nutrient subsidies from migrations of iteroparous fish whose broadcast spawning does not disturb the substrate substantially, we compared nutrient limitation, nutrient concentrations, and stream metabolism during spawning migrations of suckers (Catostomus spp.) in Lake Michigan tributaries with and without migration barriers. Although suckers deliver both nitrogen and phosphorus as eggs and waste excretion, only nitrogen concentrations were elevated during the migration (NH4‐N rose 44% relative to sites without a sucker run). Nutrient diffusing substrates demonstrated P‐limitation during the migration at sites spanning a wide range of sucker abundance, suggesting that high demand for likely masked P inputs from fish. Time series analyses indicated that gross primary production (GPP) increased with sucker excretion, but not with egg deposition after accounting for abiotic conditions. In contrast, egg deposition, but not excretion, was associated with a slight increase in ecosystem respiration (ER), suggesting that sucker gametes provide labile carbon that contributes to ER. The effects of suckers contrast with ecosystem responses to salmon migrations, which elevate ER but have mixed effects on GPP. This disparity reflects the fact that suckers fertilize streams without attendant disturbance effects. Our results suggest that basic differences in life history and behavior of migratory fish determine the direction and magnitude of their ecosystem effects. As a result, broad trait‐based predictions of the ecosystem role of migratory fishes may become possible as more species are studied.
Divergent reproductive allocation trade‐offs with canopy exposure across tree species in temperate forests
Authors: Berdanier Aaron B. , Clark James S. 
Published: July 2016

AbstractVariation in tree reproduction can alter forest community dynamics, especially if reproductive output is costly for other functions like growth. However, empirical studies reach conflicting conclusions about the constraints on reproductive allocation relative to growth and how they vary through time, across species, and between environments. Here, we test the hypothesis that a critical resource, canopy exposure to light availability, limits reproductive allocation by comparing long‐term relationships between reproduction and growth for trees from 21 species in forests throughout the Southeastern United States. We found that species have divergent responses to light availability, with shade‐intolerant species experiencing an alleviation of trade‐offs at high light‐ and shade‐tolerant species showing no changes in reproductive output across light environments. Correlations between temporal variation in individual growth and reproduction were weak and generally insensitive to canopy exposure, but changed when considering time lags. The diversity of responses across species indicates that reproductive allocation for trees in these forests is strongly influenced by both species’ life history and environmental heterogeneity in space and time.
Metapopulation dynamics guide marine reserve design: importance of connectivity, demographics, and stock enhancement
Authors: Puckett B. J. , Eggleston D. B. 
Published: July 2016

AbstractThe concepts of metapopulation persistence and source‐sink dynamics are central and often untested tenets of marine reserve networks. Effective application of these concepts to marine reserves is limited by data on demographic rates within reserves and larval connectivity among reserves. Using a network of reserves established to restore eastern oyster (Crassostrea virginica) in Pamlico Sound, North Carolina, USA as our model system, we integrated empirically based demographic rates and regional hydrodynamic‐based connectivity estimates within a metapopulation model to (1) evaluate the potential for the reserve network to function as a self‐persistent oyster metapopulation, (2) determine the relative importance of demographics vs. connectivity on reserve source‐sink dynamics, (3) assess the efficacy of stock enhancement in promoting metapopulation persistence, and (4) evaluate whether application of a Few Large or Several Small reserves—a modification of the Single Large or Several Small concept—promoted greater metapopulation retention of larvae within the reserve network (i.e., local larval retention within reserves + larval connectivity among reserves). The reserve network failed to function as a self‐persistent metapopulation, despite exceptional demographic rates within reserves. When considering only larval supply from reserves, local retention and connectivity were insufficient to provide annual replacement (≥~0.25 recruits per adult). Accordingly, reserves contributed to the metapopulation primarily via production, not dispersal, of larvae and reserve source‐sink dynamics were influenced more by demographics within reserves, particularly adult growth and survival, than larval connectivity among reserves. Addressing recruitment limitation via stock enhancement was not effective at augmenting projected metapopulation declines. Several small reserves initially promoted greater metapopulation retention of larvae than a few large reserves, however, as the number or area of reserves increased, metapopulation retention was equivalent among designs, suggesting that Few Large and Several Small reserves may be the best network design. Marine reserves can be an effective restoration tool for improving demographic rates within reserve boundaries, but designation of multiple reserves does not guarantee a functional reserve network metapopulation. Both demographics and larval connectivity are important considerations to successful application of metapopulation concepts to the design of reserve networks.
The relative contribution of climate to changes in lesser prairie‐chicken abundance
Authors: Ross Beth E. , Haukos David , Hagen Christian , Pitman James 
Published: July 2016

AbstractManaging for species using current weather patterns fails to incorporate the uncertainty associated with future climatic conditions; without incorporating potential changes in climate into conservation strategies, management and conservation efforts may fall short or waste valuable resources. Understanding the effects of climate change on species in the Great Plains of North America is especially important, as this region is projected to experience an increased magnitude of climate change. Of particular ecological and conservation interest is the lesser prairie‐chicken (Tympanuchus pallidicinctus), which was listed as “threatened” under the U.S. Endangered Species Act in May 2014. We used Bayesian hierarchical models to quantify the effects of extreme climatic events (extreme values of the Palmer Drought Severity Index [PDSI]) relative to intermediate (changes in El Niño Southern Oscillation) and long‐term climate variability (changes in the Pacific Decadal Oscillation) on trends in lesser prairie‐chicken abundance from 1981 to 2014. Our results indicate that lesser prairie‐chicken abundance on leks responded to environmental conditions of the year previous by positively responding to wet springs (high PDSI) and negatively to years with hot, dry summers (low PDSI), but had little response to variation in the El Niño Southern Oscillation and the Pacific Decadal Oscillation. Additionally, greater variation in abundance on leks was explained by variation in site relative to broad‐scale climatic indices. Consequently, lesser prairie‐chicken abundance on leks in Kansas is more strongly influenced by extreme drought events during summer than other climatic conditions, which may have negative consequences for the population as drought conditions intensify throughout the Great Plains.
Dynamic Simulation of Fixed‐Bed Chemical‐Looping Combustion Reactors Integrated in Combined Cycle Power Plants
Authors: Chen Chen , Han Lu , Bollas George M. 
Published: July 2016

AbstractChemical‐looping combustion (CLC) is a promising and efficient method for power generation with in situ CO2 capture. In this work, we focus on high‐pressure fixed‐bed CLC reactors integrated with combined cycle (CC) power plants. Specifically, the dynamic nature of fixed‐bed chemical‐looping reactors and the many kinetically controlled reactions necessitate the use of dynamic modeling to evaluate power plant performance, efficiency, stability, and feasibility under transient operation. We present a dynamic model for an integrated CLC–CC power plant and transient analyses of the integrated plant performance. A network of dynamically operated fixed‐bed reactors fed with natural gas comprises the CLC plant component. A dynamic model is developed and tuned to match the performance of a commercial combined cycle power plant. The transient variations of the integrated plant in terms of power, temperature, and pressure profiles are presented. The simulation results show that despite the inherent batch‐type operation of the CLC reactor, the operation of the combined cycle is relatively unaffected, and there are small oscillations of approximately 2 % around the desired steady‐state conditions.
On the Experimental Evidence of Exothermicity in Wood and Biomass Pyrolysis
Authors: Di Blasi Colomba , Branca Carmen , Galgano Antonio 
Published: July 2016

AbstractReaction‐induced overheating during the pyrolysis of lignocellulosic material has been reported by various authors, but it is still one of the less understood aspects of the process. This Review outlines the experimental results for a mixed kinetic‐transport control in which exothermicity is displayed clearly. The thermal conditions and the feedstock properties that enhance these events are discussed. Intraparticle activity, at the microscopic level, of homogeneous and heterogeneous reactions of vapor‐phase tars is the main cause of the strong exothermicity, which is more significant for hardly porous materials. Pyrolytic (thermal) runaway is also sometimes observed for fixed‐bed pyrolyzers. This is initiated by the fast release rate of tarry vapors at low temperatures (in the presence of catalytically active ash and significant contents of extractives and hemicelluloses) over wide spatial extensions. Then, the acceleration of the sample heating rate triggers the degradation of the other chemical components.
Performance of Perovskite‐Type Oxides as Oxygen‐Carrier Materials for Chemical Looping Combustion in the Presence of H2S
Authors: Pishahang Mehdi , Larring Yngve , Sunding Martin , Jacobs Marijke , Snijkers Frans 
Published: July 2016

AbstractIn this study, the redox behavior and the effect of the presence of sulfur on the performance of the CaTixMn0.9−xMg0.1O3 perovskite‐type system were investigated. A detailed thermodynamic and thermogravimetric approach combined with post‐characterization was utilized. Ti doping positively influenced the reduction reaction rate and broadened the operation window of the oxygen carrier material (OCM) to lower temperatures. Although sulfur accumulation during the chemical looping with oxygen uncoupling conditions was thermodynamically inevitable owing to sulfate formation, deep redox cycles were shown to remove the accumulated sulfur from the OCM after the sour cycles. Post‐characterization by scanning electron microscopy and sulfur mapping confirmed the effectiveness of this treatment.
Analysis of Catalyst Layer Microstructures: From Imaging to Performance
Authors: Sabharwal M. , Pant L. M. , Putz A. , Susac D. , Jankovic J. , Secanell M. 
Published: July 2016

AbstractImage analysis and numerical simulation algorithms are introduced to analyze the micro‐structure, transport, and electrochemical performance of thin, low platinum loading inkjet printed electrodes. A local thresholding algorithm is used to extract the catalyst layer pore morphology from focused ion beam scanning electron microscopy (FIB‐SEM) images. n‐point correlation functions, such as auto‐correlation, chord length, and pore‐size distribution are computed to interpret the micro‐structure variations between different images of the same catalyst layer. Pore size distributions are in agreement with experimental results. The catalyst layer exhibits anisotropy in the through‐plane direction, and artificial anisotropy in the FIB direction due to low slicing resolution. Microscale numerical mass transport simulations show that transport predictions are affected by image resolution and that a minimum domain size of 200 nm is needed to estimate transport properties. A micro‐scale electrochemical model that includes a description of the ionomer film resistance and a multi‐step electrochemical reaction model for the oxygen reduction reaction is also presented. Results show that the interfacial mass transport resistance in the ionomer film has the largest effect on the electrochemical performance.
Comparing Various In Vitro Prediction Criteria to Assess the Potential of a New Molecular Entity to Inhibit Organic Anion Transporting Polypeptide 1B1
Authors: Vaidyanathan Jayabharathi , Yoshida Kenta , Arya Vikram , Zhang Lei 
Published: July 2016

AbstractEvaluation of organic anion transporting polypeptide (OATP) 1B1–mediated drug‐drug interactions (DDIs) is an integral part of drug development and is recommended by regulatory agencies. In this study we compared various prediction methods and cutoff criteria based on in vitro inhibition data to assess the potential of a new molecular entity to inhibit OATP1B1 in vivo. In vitro (eg, IC50, fu,p) and in vivo (eg, dose, Cmax, change in area under the curve [AUC]) data for 11 substrates and 61 inhibitors for OATP1B1 were obtained from literature and Drugs@FDA, which include 107 clinical (in vivo) DDI studies. Substrate dependency and variability of IC50 values were noted. In addition to the ratio of unbound or total systemic concentration (Imax,u and Imax) to IC50, maximum unbound inhibitor concentration at the inlet to the liver (Iu,in,max) was used for the estimation of “R value” where R = 1 + Iu,in,max/IC50. Based on our analyses, Imax/Ki ≥ 0.1, R ≥ 1.04, or R ≥ 1.1 seem to be appropriate for reducing the false‐negative (FN) predictions. However, as compared with R ≥ 1.1, Imax/Ki ≥ 0.1 and R ≥ 1.04 resulted in higher false positives (FPs) and lower true negatives (TNs). R ≥ 1.1, Imax,u/Ki ≥ 0.02, and R ≥ 1.25 alone, or combined criterion of Imax/Ki ≥ 0.1 and R ≥ 1.25, were reasonable to determine the need to perform clinical DDI studies with OATP1B1 substrates with similar positive and negative predictive values. Possible reasons of FP or FN from different decision criteria should be considered when interpreting prediction results, and the variability in IC50 determination needs to be understood and minimized.
Renal Transporter‐Mediated Drug‐Drug Interactions: Are They Clinically Relevant?
Authors: Lepist Eve‐Irene , Ray Adrian S. 
Published: July 2016

AbstractThe kidney, through the distinct processes of passive glomerular filtration and active tubular secretion, plays an important role in the elimination of numerous endobiotics (eg, hormones, metabolites), toxins, nutrients, and drugs. Renal transport pathways mediating active tubular secretion and reabsorption in the proximal tubule are complex, involving apical and basolateral transporters acting in concert. Detailed studies of the molecular mechanisms of net active tubular secretion have established the involvement of multiple transporters with overlapping substrate specificity mediating competing secretion and reabsorption pathways. Although drug interactions arising from inhibition of renal transporters are rare relative to other mechanisms, they can involve commonly administered drugs (eg, cimetidine, metformin), may be underappreciated due to muted effects on plasma pharmacokinetics relative to tissue levels, can affect narrow‐therapeutic‐index medications (eg, antiarrhythmic, oncology medications), and may disproportionately affect sensitive populations where polypharmacy is common (eg, the elderly, diabetics). In particular, there is the potential for larger‐magnitude interactions in subjects with reduced glomerular filtration rates due to the increased relative contribution of tubular secretion. The assessment of additional endpoints in drug‐drug interaction studies including pharmacodynamics, positron emission tomography imaging, and metabolomics promises to expand our understanding of the clinical relevance of renal drug interactions.
Effect of Disease Pathologies on Transporter Expression and Function
Authors: Atilano‐Roque Amandla , Roda Gavriel , Fogueri Uma , Kiser Jennifer J. , Joy Melanie S. 
Published: July 2016

AbstractTransporters are important determinants of drug absorption, distribution, and excretion. The clinical relevance of drug transporters in drug disposition and toxicology depends on their localization in liver, kidney, and brain. There has been growing evidence regarding the importance of disease status on alterations in metabolizing enzymes and transporter proteins. This review focuses on uptake and efflux transporter proteins in liver, kidney, and brain and discusses mechanisms of altered transporter expression and function secondary to disease.
Quantification and reproducibility assessment of the regional brain T2 relaxation in naïve rats at 7T
Authors: Liachenko Serguei , Ramu Jaivijay 
Published: July 2016

PurposeTo measure the reproducibility of T2 relaxation and to determine the statistical power of T2 mapping in the rat brain as a characteristic of the baseline performance of the T2 relaxation as a potential biomarker of neurotoxicity.Materials and MethodsMultislice multiecho spin‐echo imaging was utilized to obtain the quantitative T2 maps in 138 naïve rats at 7T. Images were skull‐stripped and coregistered to the common anatomical reference. A full anatomical segmentation mask, which included all major brain structures, was created using the same reference T2 map. The overall variability map was also calculated from all T2 maps and the areas with arbitrarily high variability (coefficient of variation >25%) were excluded from the full segmentation mask to produce a trimmed mask. T2 maps were segmented using both these masks and statistical power analysis was conducted in all segmented areas.ResultsThe coefficient of variation of T2 relaxation in different brain areas varied from 5.4% (cerebrospinal fluid) to 1.2% (cortex) when using a full segmentation mask. The use of a trimmed segmentation mask decreased the coefficient of variation in many areas, which ranged between 3.2% (inferior colliculi) and 1.2% (cortex) in this case. As revealed by statistical power analysis to detect 5% change with power of 0.8, the minimum number of observations needed for different areas ranged from 3 (cortex) to 8 (inferior colliculi) in the case of use of a trimmed segmentation mask.ConclusionT2 relaxation is a very reproducible MRI parameter of the rat brain with high statistical power, which allows detecting very small changes in groups consisting of a minimal number of experimental animals.Level of Evidence: 1J. Magn. Reson. Imaging 2017;45:700–709.
An improved model for substrate in RF SOI MOSFET varactor
Authors: Li Wenjun , Chen Xiaochuan , Liu Jun 
Published: July 2016

SummaryA simple small‐signal equivalent circuit based on the physical structure of silicon‐on‐insulator metal–oxide–semiconductor field‐effect transistor varactor for substrate loss effects is presented in this paper. The model includes a BSIMSOI charge formulation and physical geometry and process parameter based on parasitic modeling. Key device performances of capacitance and quality factor are validated over voltage, frequency, and geometry. The model, implemented in Verilog‐A, provides robust and accurate radiofrequency simulation of metal–oxide–semiconductor varactor. Copyright © 2016 John Wiley & Sons, Ltd.
Derivatization coupled to headspace programmed‐temperature vaporizer gas chromatography with mass spectrometry for the determination of amino acids: Application to urine samples
Authors: González Paredes Rosa María , García Pinto Carmelo , Pérez Pavón José Luis , Moreno Cordero Bernardo 
Published: July 2016

A new method based on headspace programmed‐temperature vaporizer gas chromatography with mass spectrometry has been developed and validated for the determination of amino acids (alanine, sarcosine, ethylglycine, valine, leucine, and proline) in human urine samples. Derivatization with ethyl chloroformate was employed successfully to determine the amino acids. The derivatization reaction conditions as well as the variables of the headspace sampling were optimized.The existence of a matrix effect was checked and the analytical characteristics of the method were determined. The limits of detection were 0.15–2.89 mg/L, and the limits of quantification were 0.46–8.67 mg/L. The instrumental repeatability was 1.6–11.5%. The quantification of the amino acids in six urine samples from healthy subjects was performed with the method developed with the one‐point standard additions protocol, with norleucine as the internal standard.
Nano‐structured gemini‐based supramolecular solvent for the microextraction of cyhalothrin and fenvalerate
Authors: Feizi Neda , Yamini Yadollah , Moradi Morteza , Ebrahimpour Behnam 
Published: July 2016

A novel supramolecular solvent‐based microextraction followed by high‐performance liquid chromatography with ultraviolet detection method has been developed for the extraction and determination of two pyrethroid analytes, cyhalothrin and fenvalerate, in water and soil samples. The liquid–liquid‐phase separation of surfactants has been used in analytical extraction. The surfactant‐rich phase is a nano‐structured liquid, recently named as a supramolecular solvent, generated from the amphiphiles. The alkyl carboxylic acid based supramolecular solvents were introduced before. Coacervates made up of gemini surfactant, consisting of two amphiphilic moieties, were first used as solvent. The effective parameters on extraction (i.e., type of organic solvent, the amount of surfactant and volume of tetrahydrofuran, sample solution pH, salt addition, ultrasonic and centrifugation time) were investigated and optimized. Under the optimum conditions, preconcentration factors of 110 and 145 were obtained for the analytes. The linearity was 0.5–200.0 μg/L with the correlation of determination of (R2) ≥ 0.9984. The limit of detection of the method was (S/N = 3) 0.2 μg/L, and precisions in the range of 6.3–10.3% (RSDs, n = 5) were obtained. This method has been successfully applied to analyze real samples, and good recoveries in the range of 101.2–108.8% were obtained.