bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dehydrogenation Properties of Magnesium Hydride Loaded with Fe, Fe−C, and Fe−Mg Additives
Authors: Pukazhselvan D. , Nasani Narendar , Yang Tao , Bdikin Igor , Kovalevsky Andrei V. , Fagg Duncan P. 
Published: November 2016

AbstractThis study highlights that Fe additives offer better catalytic properties than carbon, Fe−C (iron carbide/carbon composites), and Fe‐Mg (Mg2FeH6) additives for the low‐temperature dehydrogenation of magnesium hydride. The in situ X‐ray diffraction measurements prove the formation of a Mg2FeH6 phase in iron additive loaded MgH2. Nonetheless, differential scanning calorimetry data suggest that this Mg2FeH6 phase does not have any influence on dehydrogenation properties of MgH2. On the other hand, the composite system Mg2FeH6/MgH2 shows significantly improved dehydrogenation properties even in absence of further additives. It is suggested that the improved system performance of Fe loaded MgH2 is attributed to restrictions on crystal growth of MgH2 and the catalytic behavior of Fe nanoparticles, rather than any intrinsic catalytic properties offered by the formed mixed metal phase Mg2FeH6.
Synthesis and Characterization of Fe0(2,2′‐bipyridine) (2‐aminoethyl‐pyridine) and its Reaction with Dihydrogen
Authors: Dibenedetto Angela , Roth Cristina E. , Aresta Michele , Pápai Imre 
Published: November 2016

AbstractFe0(bpy)(pyea) (2; bpy=2,2′‐bipyridine, pyea=2‐aminoethyl‐pyridine), a 16‐electron species, was synthesized by reduction of FeCl2(bpy)(pyea) (1) using Na‐strips. It is a diamagnetic low‐melting solid (m.p. 295 K) stable under N2 and easily decomposed by radiations even at low temperature. It was fully characterized by elemental analyses and multinuclear NMR. Complex 2 acts as an active hydrogenation catalyst, but has a very short lifetime. In fact, it reacts with H2 (0.1–1 MPa) at room temperature in toluene and affords in a few minutes a new Fe0 complex characterized as Fe0(bpy)(η6‐picoline) (3), inactive to hydrogenation. Picoline is derived from the sp3–sp3 C−C bond cleavage of the aminoethyl arm of the pyea ligand. The rapid evolution of the putative intermediate FeH2(bpy)(pyea) (4) has not allowed the isolation such Fe‐hydrido species. The interaction of H2 with 2 has been studied by DFT, which has allowed to demonstrate that 3 is lower in energy than 2+H2, justifying the fact that the intermediate dihydride was not isolated. Interestingly, 3 was also obtained by reaction of 1 with NaBH4 or with glycerol–KOH. Complex 2 is one of the rare examples of Fe0 complex stabilized by a set of only N‐donor atoms. The reaction with glycerol confirms the potential role of Fe in catalytic hydrogenation reactions using bio‐glycerol as a H‐source.
The Future of Ethenolysis in Biobased Chemistry
Authors: Spekreijse Jurjen , Sanders Johan P. M. , Bitter Johannes H. , Scott Elinor L. 
Published: November 2016

AbstractThe desire to utilise biobased feedstocks and develop more sustainable chemistry poses new challenges in catalysis. A synthetically useful catalytic conversion is ethenolysis, a cross metathesis reaction with ethylene. In this Review, the state of the art of ethenolysis in biobased chemistry was extensively examined using methyl oleate as a model compound for fatty acids. Allied to this, the ethenolysis of fatty acid, polymers and more challenging substrates are reviewed. To determine the limiting factors for the application of ethenolysis on biomass, the influence of reaction parameters were investigated and the bottlenecks for reaching high turnover numbers identified.
Psychophysiological Assessment of the Adaptive Asynchronous Human–Machine System on the Operation Period Discrimination Characteristic
Authors: NOZAWA AKIO , HOSODA YUSUKE 
Published: November 2016

SUMMARYThis paper proposes a concept of the adaptive asynchronous human machine system (Async‐HMS) which maintains asynchronous periodic operations against user's actions for avoiding user intention. In order to find the dynamics of the operation period presented by Async‐HMS, discrimination thresholds of the operation period were obtained by psychophysical experiment. According to the thresholds, three levels of fluctuation of the operation period were defined as “constant”, “unrecognizable”, and “recognizable”. Psychophysiological measurement was conducted on the performance of the synchronized key typing task by the three levels of the operation period. A synchronization error as performance index, the hemodynamic parameters as indices of autonomic nervous system's activity, and the amount of the senses as psychological indices were evaluated. As a result, monotonous feeling was eliminated without compromising the performance in case of “unrecognizable” fluctuations in the operation period presented by Async‐HMS.
Size Effect and Aperture Configuration Dependence of Extraordinary Optical Transmission through Penrose Metal Hole Arrays in the Terahertz Region
Authors: JIMBA YOJI , MIYAZAKI HIROSHI 
Published: November 2016

SUMMARYExtraordinary optical transmission (EOT) through Penrose metal hole arrays (PMHA) in the terahertz region is investigated numerically by using coupled‐mode analysis. Spectral change of the transmittance is studied at resonant frequencies by increasing the number of holes and comparing the spectra of PMHA and a periodic metal hole arrays (MHA). While the resonant mode of MHA is excited in periodic order along one direction, the resonant mode on PMHA has a complicated shape. It seems that the propagating length of surface wave of PMHA is shorter than that of the MHA. Therefore, when the number of holes is increased, increasing rate of the resonant transmittance through PMHA is smaller than that through MHA. In addition, the transmission spectra for three kinds of generalized PHMA are analyzed numerically. Although the distributions of holes in these PMHA are different from each other in real space, the transmission spectra have almost the same shape. Consequently, the structure given by the aperture configuration of PMHA in reciprocal lattice space has stronger effects on EOT through metal hole arrays, rather than that in real space.
Effect of Compressive Stress on Iron Loss of Gradient Si Steel Sheet
Authors: ODA YOSHIHIKO , HIRATANI TATSUHIKO , KASAI SHOJI , OKUBO TOMOYUKI , SENDA KUNIHIRO , CHIBA AKIRA 
Published: November 2016

SUMMARYA gradient Si steel sheet, which has high Si content in the surface layer and low Si content in the center of the thickness, shows extremely low iron loss in the high‐frequency range. In this paper, the magnetic properties of gradient Si steel sheets under compressive stress were investigated. In a 3.5% Si steel sheet, the iron loss under compressive stress increases with increase in compressive stress. On the other hand, a gradient Si steel sheet shows extremely low iron loss under compressive stress. This decrease is due to the residual tensile stress in the surface layer of the gradient Si steel sheet. To evaluate the effect of core materials on the iron loss of the motor, we fabricated interior permanent magnet motors using 3% Si steel, 6.5% Si steel, and gradient Si steel sheets. In the motor using a 3% Si steel sheet, the motor loss increases after the heat shrinking. On the other hand, in the motors using 6.5% Si steel and gradient Si steel sheets, the motor loss shows little change after the heat shrinking.
Beachgrass invasion in coastal dunes is mediated by soil microbes and lack of disturbance dependence
Authors: David Aaron S. , May Georgiana , Schmidt Derek , Seabloom Eric W. 
Published: November 2016

AbstractBiological invasions are a threat to ecological communities and ecosystems, yet understanding the processes that mediate invasion and the environmental contexts in which these processes are important remains a challenge. In this study, we investigated how disturbance and biotic interactions with pathogens and microbial symbionts mediate invasion of American beachgrass (Ammophila breviligulata) in early‐ and late‐successional coastal dune habitats. First, we tested the effect of disturbance on biomasses of two exotic beachgrass species (the invading A. breviligulata and the established A. arenaria) and a native beachgrass (Elymus mollis) by growing plants with and without a disturbance manipulation in early‐ and late‐successional habitats. We quantified root colonization by fungal symbionts and infection by plant‐parasitic nematodes to determine the effect of potential mutualists and pathogens on plant biomass. Second, we tested whether soil microbes associated with the established A. arenaria mediated A. breviligulata invasion by inoculating potted plants with microbes from early‐ and late‐successional habitat. We found no effect of disturbance on biomass of the invading A. breviligulata or native E. mollis, whereas A. arenaria biomass increased when grown with disturbance. Colonization by arbuscular mycorrhizal fungi and by fungal endophytes were poor predictors of plant biomass, and plant‐parasitic nematodes were infrequently observed. Microbe addition increased belowground biomass of A. breviligulata, but not A. arenaria, compared to control treatments. Overall, our results suggest that A. breviligulata invasion in both the early‐ and late‐successional habitat is mediated by its lack of disturbance dependence and positive effects of soil microbes. These results have important implications for other primary successional systems and contribute to our understanding of how ecological contexts influence invasion processes.
Habitat availability and depth‐driven population demographics regulate reproductive output of a coral reef fish
Authors: Goldstein E. D. , D'Alessandro E. K. , Reed J. , Sponaugle S. 
Published: November 2016

AbstractGlobal habitat decline may displace organisms from optimal environments, increasing reliance on ecosystems with lower habitat suitability and availability. For coral reef fishes, potentially marginal mesophotic coral ecosystems (~30–150 m) may be buffered from anthropogenic stressors; however, variation in habitat quality across depths can alter population demographics, reproductive output, and subpopulation size, potentially restricting the ability for peripheral habitats to support declining populations through larval supply. This study incorporated population density, benthic habitat, and depth‐stratified population demographics to assess bicolor damselfish (Stegastes partitus) subpopulation reproductive output from a broad geographic region encompassing the known depth distribution of the species, including coral reefs in the Florida Keys (0–35 m depths) and mesophotic reefs (~60–90 m) at Pulley Ridge (PR) on the west Florida Shelf. Results indicated that densities of bicolor damselfish peaked in mid‐shelf (10–20 m) and deep‐shelf (20–30 m) habitats, and subpopulation sizes and reproductive output peaked at mid‐depths (10–20 m) in the Florida Keys and declined as depth increased. Subpopulation egg production was affected by differences in demographics across depths, including fish size, sex ratios, and a lower probability and frequency of spawning in deeper habitats. Despite low population densities on mesophotic reefs, the expansive reef area at PR resulted in an estimated subpopulation size that comprised ~14% of the population in the study region, and ~9% of the total reproductive output, indicating that peripheral mesophotic reefs may be sources of larvae that can subsidize declining populations. Larval dispersal and population connectivity models used to inform ecosystem management should incorporate spatially explicit demographics across depth distributions and habitat availability that have substantial effects on egg production and larval supply.
Using structural equation modeling to link human activities to wetland ecological integrity
Authors: Schweiger E. William , Grace James B. , Cooper David , Bobowski Ben , Britten Mike 
Published: November 2016

AbstractThe integrity of wetlands is of global concern. A common approach to evaluating ecological integrity involves bioassessment procedures that quantify the degree to which communities deviate from historical norms. While helpful, bioassessment provides little information about how altered conditions connect to community response. More detailed information is needed for conservation and restoration. We have illustrated an approach to addressing this challenge using structural equation modeling (SEM) and long‐term monitoring data from Rocky Mountain National Park (RMNP). Wetlands in RMNP are threatened by a complex history of anthropogenic disturbance including direct alteration of hydrologic regimes; elimination of elk, wolves, and grizzly bears; reintroduction of elk (absent their primary predators); and the extirpation of beaver. More recently, nonnative moose were introduced to the region and have expanded into the park. Bioassessment suggests that up to half of the park's wetlands are not in reference condition. We developed and evaluated a general hypothesis about how human alterations influence wetland integrity and then develop a specific model using RMNP wetlands. Bioassessment revealed three bioindicators that appear to be highly sensitive to human disturbance (HD): (1) conservatism, (2) degree of invasion, and (3) cover of native forbs. SEM analyses suggest several ways human activities have impacted wetland integrity and the landscape of RMNP. First, degradation is highest where the combined effects of all types of direct HD have been the greatest (i.e., there is a general, overall effect). Second, specific HDs appear to create a “mixed‐bag” of complex indirect effects, including reduced invasion and increased conservatism, but also reduced native forb cover. Some of these effects are associated with alterations to hydrologic regimes, while others are associated with altered shrub production. Third, landscape features created by historical beaver activity continue to influence wetland integrity years after beavers have abandoned sites via persistent landforms and reduced biomass of tall shrubs. Our model provides a system‐level perspective on wetland integrity and provides a context for future evaluations and investigations. It also suggests scientifically supported natural resource management strategies that can assist in the National Park Service mission of maintaining or, when indicated, restoring ecological integrity “unimpaired for future generations.”
Carbon dioxide fluxes reflect plant zonation and belowground biomass in a coastal marsh
Authors: Moseman‐Valtierra Serena , Abdul‐Aziz Omar I. , Tang Jianwu , Ishtiaq Khandker S. , Morkeski Kate , Mora Jordan , Quinn Ryan K. , Martin Rose M. , Egan Katharine , Brannon Elizabeth Q. , Carey Joanna , Kroeger Kevin D. 
Published: November 2016

AbstractCoastal wetlands are major global carbon sinks; however, they are heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, greenhouse gas (GHG) fluxes were compared among major plant‐defined zones during growing seasons. Carbon dioxide (CO2) and methane (CH4) fluxes were compared in two mensurative experiments during summer months (2012–2014) that included low marsh (Spartina alterniflora), high marsh (Distichlis spicata and Juncus gerardii‐dominated), invasive Phragmites australis zones, and unvegetated ponds. Day‐ and nighttime fluxes were also contrasted in the native marsh zones. N2O fluxes were measured in parallel with CO2 and CH4 fluxes, but were not found to be significant. To test the relationships of CO2 and CH4 fluxes with several native plant metrics, a multivariate nonlinear model was used. Invasive P. australis zones (−7 to −15 μmol CO2·m−2·s−1) and S. alterniflora low marsh zones (up to −14 μmol CO2·m−2·s−1) displayed highest average CO2 uptake rates, while those in the native high marsh zone (less than −2 μmol CO2·m−2·s−1) were much lower. Unvegetated ponds were typically small sources of CO2 to the atmosphere (<0.5 μmol CO2·m−2·s−1). Nighttime emissions of CO2 averaged only 35% of daytime uptake in the low marsh zone, but they exceeded daytime CO2 uptake by up to threefold in the native high marsh zone. Based on modeling, belowground biomass was the plant metric most strongly correlated with CO2 fluxes in native marsh zones, while none of the plant variables correlated significantly with CH4 fluxes. Methane fluxes did not vary between day and night and did not significantly offset CO2 uptake in any vegetated marsh zones based on sustained global warming potential calculations. These findings suggest that attention to spatial zonation as well as expanded measurements and modeling of GHG emissions across greater temporal scales will help to improve accuracy of carbon accounting in coastal marshes.
Stable isotopes predict reproductive performance of European starlings breeding in anthropogenic environments
Authors: Yohannes Elizabeth , Gwinner Helga , Lee Raymond W. , Schwabl Hubert 
Published: November 2016

AbstractUnderstanding reproductive performance in ecologically impoverished vs. more sustained anthropogenic habitats is critical to assess population health status and to develop land use and conservation management strategies. We compared resource‐based maternal effects, reproductive performance, and offspring quality in a model migratory passerine bird, the European starling (Sturnus vulgaris). We assessed female condition, quantity of egg constituents, quality of diet consumed during egg formation, and nestling growth and survival in two habitats: cultivated farmland and meadows. Egg, albumin, and shell mass were greater at the meadow site, while yolk mass did not differ significantly between sites; albumin mass most strongly predicted egg mass. Stable isotope enrichment (δ15N and δ13C) in yolk but not albumin suggests a broader range of diet for yolk formation at the meadow site but could also reflect different hydric conditions between sites. δ13C and δ15N enrichment did not predict yolk, albumin, or egg mass. Concentration of yolk testosterone was higher at the meadow site and correlated with δ13C enrichment in yolk. Nestling survival was higher in the meadow than in the farmland site and corresponded to egg mass and δ13C enrichment in lipid‐free yolk. Surviving nestlings were larger in the meadow than in the farmland site. Results indicate that agricultural practice influences reproductive output through resource‐based maternal effects. The analyses of isotopic and biochemical composition of small samples of yolk and albumin may provide a minimally invasive tool to assess individual reproductive performance and predict impacts of habitat quality on population health.
Host genus and rainfall drive the population dynamics of a vascular epiphyte
Authors: Ticktin Tamara , Mondragón Demetria , Gaoue Orou G. 
Published: November 2016

AbstractVascular epiphytes constitute up to 25% of tropical plant diversity and play an important role in providing food, water, and shelter to many organisms. However, the factors that drive their population dynamics, including the influence of their host plants (phorophytes) and of climatic factors, are still poorly understood. We provide the first test of whether host tree genus can affect population dynamics of an epiphytic species, and assess the interactive effects of host tree and rainfall. We carried out a five‐year study of the demography of >1000 plants of the endemic bromeliad, Tillandsia macdougallii L. B. Sm, growing on pine and oak trees in a Mexican montane forest. We tested for differences in vital rates and used integral projection models to test whether these scaled up to differences in long‐term population growth rates between the two host genera and as a function of rainfall. T. macdougallii survival and growth were higher on pines than on oaks for larger plants but not for seedlings. The probability of producing capsules was higher for T. macdougallii on oaks than on pines. Increasing dry season rainfall was significantly correlated with increased survival of individuals, but not of ramets, growing on both oaks and pines. The probability of clonal reproduction increased significantly with increasing dry season rainfall for T. macdougallii growing on oaks, but not on pines. Projected long‐term population growth rates, λ, for T. macdougallii on pines were higher than on oaks. Lambda increased steeply as a function of dry season rainfall for T. macdougallii populations on both host tree genera, but the increase was steeper for populations on oaks, likely because the former are deciduous. Our results show that host tree genus can affect the long‐term dynamics of epiphyte populations and suggest that these effects may depend on rainfall. The high sensitivity of this species to changes in dry season rainfall suggests that a better understanding of how rainfall may drive vascular epiphyte populations will be critical for understanding the effects of climate change on species persistence.
Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model
Authors: Byrd Kristin B. , Windham‐Myers Lisamarie , Leeuw Thomas , Downing Bryan , Morris James T. , Ferner Matthew C. 
Published: November 2016

AbstractReducing uncertainty in data inputs at relevant spatial scales can improve tidal marsh forecasting models, and their usefulness in coastal climate change adaptation decisions. The Marsh Equilibrium Model (MEM), a one‐dimensional mechanistic elevation model, incorporates feedbacks of organic and inorganic inputs to project elevations under sea‐level rise scenarios. We tested the feasibility of deriving two key MEM inputs—average annual suspended sediment concentration (SSC) and aboveground peak biomass—from remote sensing data in order to apply MEM across a broader geographic region. We analyzed the precision and representativeness (spatial distribution) of these remote sensing inputs to improve understanding of our study region, a brackish tidal marsh in San Francisco Bay, and to test the applicable spatial extent for coastal modeling. We compared biomass and SSC models derived from Landsat 8, DigitalGlobe WorldView‐2, and hyperspectral airborne imagery. Landsat 8‐derived inputs were evaluated in a MEM sensitivity analysis. Biomass models were comparable although peak biomass from Landsat 8 best matched field‐measured values. The Portable Remote Imaging Spectrometer SSC model was most accurate, although a Landsat 8 time series provided annual average SSC estimates. Landsat 8‐measured peak biomass values were randomly distributed, and annual average SSC (30 mg/L) was well represented in the main channels (IQR: 29–32 mg/L), illustrating the suitability of these inputs across the model domain. Trend response surface analysis identified significant diversion between field and remote sensing‐based model runs at 60 yr due to model sensitivity at the marsh edge (80–140 cm NAVD88), although at 100 yr, elevation forecasts differed less than 10 cm across 97% of the marsh surface (150–200 cm NAVD88). Results demonstrate the utility of Landsat 8 for landscape‐scale tidal marsh elevation projections due to its comparable performance with the other sensors, temporal frequency, and cost. Integration of remote sensing data with MEM should advance regional projections of marsh vegetation change by better parameterizing MEM inputs spatially. Improving information for coastal modeling will support planning for ecosystem services, including habitat, carbon storage, and flood protection.