bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upstream control of the frontal jet regulating plankton production in the Alboran Sea (Western Mediterranean)
Authors: Oguz Temel , Mourre Baptiste , Tintoré Joaquín 
Published: August 2016

AbstractUsing a coupled physical‐biological model, we document that a ∼30 km wide meandering jet constitutes a major source of biological enrichment in the Alboran Sea (Western Mediterranean) even in the absence of wind forcing and tidal dynamics. The level of enrichment is shown to vary markedly during the year depending on the upstream characteristics of the jet as it exits from the Gibraltar Strait. When its intensity is sufficiently low and characterized by weaker cross‐frontal density gradients during winter‐spring, the jet is weakly nonlinear and may not fulfill the necessary conditions for frontogenesis. It then remains weakly productive. In the case of stronger jet intensity (>1.1 Sv) accompanied by stronger cross‐frontal density and velocity gradients within the Alboran Sea during summer‐autumn, the frontal jet becomes strongly nonlinear and ageostrophic with large cross‐frontal vorticity changes on the order of planetary vorticity. Under these conditions, upward vertical velocities in the range 10–50 m d−1 supply nutrients into the euphotic layer more effectively and support high‐level frontogenesis‐induced phytoplankton production on the anticyclonic side of the main jet axis. The strong eddy pumping mechanism also provides a comparable level of plankton production within strongly nonlinear elongated cyclonic eddies along the outer periphery of the frontal jet. The plankton biomass is advected partially by the jet along its trajectory and dispersed within the basin by mesoscale eddies and meanders.
Regionalization of land‐use impacts on streamflow using a network of paired catchments
Authors: Ochoa‐Tocachi Boris F. , Buytaert Wouter , De Bièvre Bert 
Published: August 2016

AbstractQuantifying the impact of land use and cover (LUC) change on catchment hydrological response is essential for land‐use planning and management. Yet hydrologists are often not able to present consistent and reliable evidence to support such decision‐making. The issue tends to be twofold: a scarcity of relevant observations, and the difficulty of regionalizing any existing observations. This study explores the potential of a paired catchment monitoring network to provide statistically robust, regionalized predictions of LUC change impact in an environment of high hydrological variability. We test the importance of LUC variables to explain hydrological responses and to improve regionalized predictions using 24 catchments distributed along the Tropical Andes. For this, we calculate first 50 physical catchment properties, and then select a subset based on correlation analysis. The reduced set is subsequently used to regionalize a selection of hydrological indices using multiple linear regression. Contrary to earlier studies, we find that incorporating LUC variables in the regional model structures increases significantly regression performance and predictive capacity for 66% of the indices. For the runoff ratio, baseflow index, and slope of the flow duration curve, the mean absolute error reduces by 53% and the variance of the residuals by 79%, on average. We attribute the explanatory capacity of LUC in the regional model to the pairwise monitoring setup, which increases the contrast of the land‐use signal in the data set. As such, it may be a useful strategy to optimize data collection to support watershed management practices and improve decision‐making in data‐scarce regions.
River bank geomorphology controls groundwater arsenic concentrations in aquifers adjacent to the Red River, Hanoi Vietnam
Authors: Stahl Mason O. , Harvey Charles F. , van Geen Alexander , Sun Jing , Thi Kim Trang Pham , Mai Lan Vi , Mai Phuong Thao , Hung Viet Pham , Bostick Benjamin C. 
Published: August 2016

AbstractMany aquifers that are highly contaminated by arsenic in South and Southeast Asia are in the floodplains of large river networks. Under natural conditions, these aquifers would discharge into nearby rivers; however, large‐scale groundwater pumping has reversed the flow in some areas so that rivers now recharge aquifers. At a field site near Hanoi Vietnam, we find river water recharging the aquifer becomes high in arsenic, reaching concentrations above 1000 µg/L, within the upper meter of recently (< ∼10 years) deposited riverbed sediments as it is drawn into a heavily pumped aquifer along the Red River. Groundwater arsenic concentrations in aquifers adjacent to the river are largely controlled by river geomorphology. High (>50 µg/L) aqueous arsenic concentrations are found in aquifer regions adjacent to zones where the river has recently deposited sediment and low arsenic concentrations are found in aquifer regions adjacent to erosional zones. High arsenic concentrations are even found adjacent to a depositional river reach in a Pleistocene aquifer, a type of aquifer sediment which generally hosts low arsenic water. Using geochemical and isotopic data, we estimate the in situ rate of arsenic release from riverbed sediments to be up to 1000 times the rates calculated on inland aquifer sediments in Vietnam. Geochemical data for riverbed porewater conditions indicate that the reduction of reactive, poorly crystalline iron oxides controls arsenic release. We suggest that aquifers in these regions may be susceptible to further arsenic contamination where riverine recharge drawn into aquifers by extensive groundwater pumping flows through recently deposited river sediments before entering the aquifer.
Alkynes as Linchpins for the Additive Annulation of Biphenyls: Convergent Construction of Functionalized Fused Helicenes
Authors: Mohamed Rana K. , Mondal Sayantan , Guerrera Joseph V. , Eaton Teresa M. , Albrecht‐Schmitt Thomas E. , Shatruk Michael , Alabugin Igor V. 
Published: August 2016

AbstractA new approach to fused helicenes is reported, where varied substituents are readily incorporated in the extended aromatic frame. From the alkynyl precursor, the final helical compounds are obtained under mild conditions in a two‐step process, in which the final C−C bond is formed via a photochemical cyclization/ dehydroiodination sequence. The distortion of the π‐system from planarity leads to unusual packing in the solid state. Computational analysis reveals that substituent incorporation perturbs geometries and electronic structures of these nonplanar aromatics.
Mangiferin modulation of metabolism and metabolic syndrome
Authors: Fomenko Ekaterina Vladimirovna , Chi Yuling 
Published: August 2016

AbstractThe recent emergence of a worldwide epidemic of metabolic disorders, such as obesity and diabetes, demands effective strategy to develop nutraceuticals or pharmaceuticals to halt this trend. Natural products have long been and continue to be an attractive source of nutritional and pharmacological therapeutics. One such natural product is mangiferin (MGF), the predominant constituent of extracts of the mango plant Mangifera indica L. Reports on biological and pharmacological effects of MGF increased exponentially in recent years. MGF has documented antioxidant and anti‐inflammatory effects. Recent studies indicate that it modulates multiple biological processes involved in metabolism of carbohydrates and lipids. MGF has been shown to improve metabolic abnormalities and disorders in animal models and humans. This review focuses on the recently reported biological and pharmacological effects of MGF on metabolism and metabolic disorders. © 2016 BioFactors, 42(5):492–503, 2016
Aza‐Michael Reactions of Isatin Imines: Deeper Insight and Origin of the Stereoselectivity
Authors: Metsala Andrus , Žari Sergei , Kanger Tõnis 
Published: August 2016

AbstractAn asymmetric organocatalytic aza‐Michael reaction of imines derived from isatin with unsaturated 1,4‐dicarbonyl compounds was investigated by means of DFT calculations. It was found that, in addition to the activation of the reactants by hydrogen bonds, several π–π interactions were responsible for the high enantioselectivity of the reaction. In the computationally proposed transition state model, an interaction of the sulfur atom of the thiourea catalyst and aromatic π‐electron system of the phenyl ring of imine occurred, providing high selectivity.
On the Nature of Bridging Metal Atoms in Intermetalloid Clusters: Synthesis and Structure of the Metal‐Atom‐Bridged Zintl Clusters [Sn(Ge9)2]4− and [Zn(Ge9)2)]6−
Authors: Bentlohner Manuel M. , Jantke Laura‐Alice , Henneberger Thomas , Fischer Christina , Mayer Kerstin , Klein Wilhelm , Fässler Thomas F. 
Published: August 2016

AbstractThe addition of Sn and Zn ions to [Ge9] clusters by reaction of [Ge9]4− with SnPh2Cl2, ZnCp*2 (Cp*=pentamethylcyclopentadienyl), or Zn2[HC(Ph2P=NPh)2]2 is reported. The resulting Sn‐ and Zn‐bridged clusters [(Ge9)M(Ge9)]q− (M=Sn, q=4; M=Zn, q=6) display various coordination modes. The M atoms that coordinate to the open square of a C4v‐symmetric [Ge9] cluster form strong covalent multicenter M−Ge bonds, in contrast to the M atoms coordinating to triangular cluster faces. Molecular orbital analyses show that the M atoms of the Ge9M fragments coordinate to a second [Ge9] cluster with similar orbitals but in different ways. The [Ge9Sn]2−unit donates two electrons to the triangular face of a second [Ge9]2− cluster with D3h symmetry, whereas [Ge9Zn]2−acts as an electron acceptor when interacting with the triangular face of a D3h‐symmetric [Ge9]4− unit.
Electron Transport in Quasi‐Two‐Dimensional Porous Network of Titania Nanoparticles, Incorporating Electrical and Optical Advantages in Dye‐Sensitized Solar Cells
Authors: Javadi Mohammad , Alizadeh Saba , Khosravi Yusef , Abdi Yaser 
Published: August 2016

AbstractThe integration of fast electron transport and large effective surface area is critical to attaining higher gains in the nanostructured photovoltaic devices. Here, we report facilitated electron transport in the quasi‐two‐dimensional (Q2D) porous TiO2. Liquid electrolyte dye‐sensitized solar cells were prepared by utilizing photoanodes based on the Q2D porous substructures. Due to electron confinement in a microscale porous medium, directional diffusion toward collecting electrode is induced into the electron transport. Our measurements based on the photocurrent and photovoltage time‐of‐flight transients show that at higher Fermi levels, the electron diffusion coefficient in the Q2D porous TiO2 is about one order of magnitude higher when compared with the conventional layer of porous TiO2. The results show that microstructuring of the porous TiO2 leads to an approximately threefold improvement in the electron diffusion length. Such a modification may considerably affects the electrical functionality of moderate or low performance dye‐sensitized solar cells for which the internal gain or collection efficiency is typically low.
Material and Device Stability in Perovskite Solar Cells
Authors: Kim Hui‐Seon , Seo Ja‐Young , Park Nam‐Gyu 
Published: August 2016

AbstractOrganic–inorganic halide perovskite solar cells have attracted great attention because of their superb efficiency reaching 22 % and low‐cost, facile fabrication processing. Nevertheless, stability issues in perovskite solar cells seem to block further advancements toward commercialization. Thus, device stability is one of the important topics in perovskite solar cell research. In the beginning, the poor moisture resistivity of the perovskite layer was considered as a main problem that hindered further development of perovskite solar cells, which encouraged engineering of the perovskite or protection of the perovskite by a buffer layer. Soon after, other parameters affecting long‐term stability were sequentially found and various attempts have been made to enhance intrinsic and extrinsic stability. Here we review the recent progresses addressing stability issues in perovskite solar cells. In this report, we investigated factors affecting stability from material and device points of view. To gain a better understanding of the stability of the bulk perovskite material, decomposition mechanisms were investigated in relation to moisture, photons, and heat. Stability of full device should also be carefully examined because its stability is dependent not only on bulk perovskite but also on the interfaces and selective contacts. In addition, ion migration and current–voltage hysteresis were found to be closely related to stability.
A new bridgeless buck PFC rectifier
Authors: Hwu K. I. , Shieh Jenn‐Jong , Jiang W. Z. 
Published: August 2016

SummaryIn this study, a new bridgeless buck power factor correction (PFC) rectifier is presented. The proposed buck PFC rectifier is designed to operate in the discontinuous conduction mode (DCM). Because of the DCM operation, the control scheme of the proposed buck PFC rectifier is simple and easy, and the reverse recovery problem of the diodes can be alleviated. Because the input current follows the input voltage naturally, the current loop circuit is not required. Thus, only the traditional voltage‐mode control is employed to sense the output voltage, and a suitable control effort for the proposed buck PFC rectifier is generated to drive the power switches. Consequently, the output voltage of the proposed buck PFC rectifier can be kept at a desired value. Finally, the mathematical deductions and experimental results are provided to verify the effectiveness of the proposed bridgeless buck PFC rectifier. Copyright © 2016 John Wiley & Sons, Ltd.
Metacognitive learning in the ecology classroom: A tool for preparing problem solvers in a time of rapid change?
Authors: Spellman Katie V. , Deutsch Andrea , Mulder Christa P. H. , Carsten‐Conner Laura D. 
Published: August 2016

AbstractBuilding communities that are resilient and adaptive to climate change requires the development of education strategies that train community members in higher order thinking skills that can be used to solve complex environmental problems. This study provides an empirical test of hypotheses within social‐ecological systems resilience theory that have suggested metacognitive learning strategies could increase resilience thinking skills such as scenarios thinking, systems thinking, and the ability to interpret and apply ecological data in complex problem solving. During a 6‐week long ecology unit with 108 seventh‐grade students, we taught half the students using standard inquiry teaching methods and the other half using the same method, with the addition of a daily metacognitive learning intervention. We investigated the short‐term (after six weeks of intervention) and long‐term (1 yr after the intervention ended) effects of the intervention on student's metacognitive ability and resilience thinking skills. Over the long term, we found a modest increase in the metacognitive ability of students who received the daily metacognitive journaling exercise. Interview data suggest that the structured metacognitive practice did most to improve the resilience thinking level of students who had low resilience thinking ability prior to the intervention period. However, the interaction between pre‐treatment ability level and the treatment group was not detected in the written assessment data. These data suggest that the metacognitive learning intervention we used can benefit metacognitive ability over the long term, but has limited transferability to resilience thinking skills for most students. We suggest additional instructional practices for implementing metacognitive teaching approaches that could enhance the generalizability of their benefits across resilience thinking skills and student's ability levels.
Seasonal variation exceeds effects of salmon carcass additions on benthic food webs in the Elwha River
Authors: Morley S. A. , Coe H. J. , Duda J. J. , Dunphy L. S. , McHenry M. L. , Beckman B. R. , Elofson M. , Sampson E. M. , Ward L. 
Published: August 2016

AbstractDam removal and other fish barrier removal projects in western North America are assumed to boost freshwater productivity via the transport of marine‐derived nutrients from recolonizing Pacific salmon (Oncorhynchus spp.). In anticipation of the removal of two hydroelectric dams on the Elwha River in Washington State, we tested this hypothesis with a salmon carcass addition experiment. Our study was designed to examine how background nutrient dynamics and benthic food webs vary seasonally, and how these features respond to salmon subsidies. We conducted our experiment in six side channels of the Elwha River, each with a spatially paired reference and treatment reach. Each reach was sampled on multiple occasions from October 2007 to August 2008, before and after carcass placement. We evaluated nutrient limitation status; measured water chemistry, periphyton, benthic invertebrates, and juvenile rainbow trout (O. mykiss) response; and traced salmon‐derived nutrient uptake using stable isotopes. Outside of winter, algal accrual was limited by both nitrogen and phosphorous and remained so even in the presence of salmon carcasses. One month after salmon addition, dissolved inorganic nitrogen levels doubled in treatment reaches. Two months after addition, benthic algal accrual was significantly elevated. We detected no changes in invertebrate or fish metrics, with the exception of 15N enrichment. Natural seasonal variability was greater than salmon effects for the majority of our response metrics. Yet seasonality and synchronicity of nutrient supply and demand are often overlooked in nutrient enhancement studies. Timing and magnitude of salmon‐derived nitrogen utilization suggest that uptake of dissolved nutrients was favored over direct consumption of carcasses. The highest proportion of salmon‐derived nitrogen was incorporated by herbivores (18–30%) and peaked 1–2 months after carcass addition. Peak nitrogen enrichment in predators (11–16%) occurred 2–3 months after addition. All taxa returned to background δ15N levels by 7 months. Since this study was conducted, both dams on the Elwha River were removed over 2011–2014 to open over 90% of the basin to anadromous fishes. We anticipate that as the full portfolio of salmon species expands through the basin, nutrient supply and demand will come into better balance.
Seasonal trophic linkages in Arctic marine invertebrates assessed via fatty acids and compound‐specific stable isotopes
Authors: Mohan Stephanie D. , Connelly Tara L. , Harris Carolynn M. , Dunton Kenneth H. , McClelland James W. 
Published: August 2016

AbstractClimate change is having profound impacts on Arctic ecosystems with important implications for coastal productivity and food web dynamics. We investigated seasonal variations in resource use of 16 invertebrate taxa in lagoon ecosystems along the Alaska Beaufort Sea coast using a combination of fatty acid (FA) biomarkers, bulk stable carbon isotope measurements of whole animals, and compound‐specific stable carbon isotope measurements of total lipid extracts and individual FAs. Invertebrates were collected during full‐ice cover (April), ice breakup (June), and open water (August) periods. Amphipods (Onisimus glacialis) had higher proportions of 18:2n‐6 and 18:3n‐3 FAs in April than in the other months. These elevated markers were accompanied by relatively low bulk and 18:2n‐6 δ13C values, indicating proportionally higher contributions from terrestrial/freshwater sources in April. A wider range of invertebrates examined during June and August showed increases in algae‐specific markers and higher proportions of essential FAs (e.g., 22:6n‐3 [docosahexaenoic acid] and 20:5n‐3 [eicosapentaenoic acid]) later in the summer. There were also marked differences in FA characteristics among invertebrates that highlighted differential feeding modes. For example, proportions of bacterial FAs were generally higher in deposit‐feeding invertebrates than in suspension feeders. These results highlight the current role of diverse carbon sources to Arctic coastal food webs, which may change with future warming.
Policy Diffusion in the Context of International River Basin Management
Authors: Metz Florence , Fischer Manuel 
Published: August 2016

AbstractThis paper deals with policy diffusion across countries in the context of collaborative river basin management. Borrowing from the literature on policy diffusion and ‘smart strategies’ of small European Union member states, we argue that policy diffusion is fostered by structural and agency‐related factors. We illustrate our theoretical ideas with a case study on the new Swiss policy on micropollutants in surface waters. Based on a rich set of documents and interviews with key actors, we show that the integration of Switzerland into formal and informal transnational networks fosters the diffusion of its micropollutants policy to other Rhine riparian countries. In addition, we analyse agency‐related factors favouring policy diffusion in river basins, such as a country's pioneer role, its expertise, the fact that its policy is in line with general policy goals in other countries and the political acceptance of the policy at home. Our analysis suggests that policy diffusion can be an important phenomenon in integrated water resources management. Copyright © 2016 John Wiley & Sons, Ltd and ERP Environment.
High‐Performance Electrocatalytic Activity of Palladium‐Copper Nanoalloy towards Methanol Electro‐oxidation in an Alkaline Medium
Authors: Arulmani Subramanian , Krishnamoorthy Sathiyan , Wu Jerry J. , Anandan Sambandam 
Published: August 2016

AbstractNanoalloy of PdCu were synthesized with three different stoichiometry ratio (3 : 1, 1 : 1, 1 : 3) by simple co‐reduction process at 5 °C with Triton X‐100 as surface modifier. Morphology and composition of the synthesized catalyst were characterized by X‐ray diffraction (XRD), X‐ray photo electron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X‐ray analysis (EDAX) with selected area electron diffraction (SAED) techniques. Electrocatalytic activity and stability of the catalysts towards methanol oxidation reaction were verified in alkaline medium by cyclic voltammetry (CV) and chronoamperometry (CA). Observed results emphasis that PdCu nanoalloy in the 3 : 1 stoichiometric ratio shows better catalytic activity (778.98 mA mg−1) and stability not only in the initial state (93.73 mA mg−1) but also after 1800 s (8.61 mA mg−1) among all other prepared catalysts.
A Two‐step Anodic Thiocyanation of Alkenes in Formic Acid
Authors: Gitkis Anna , Becker James Y. 
Published: August 2016

AbstractInitial formation of thiocyanogen [(SCN)2] by controlled potential anodic oxidation of NH4SCN in formic acid‐LiClO4 followed by addition of alkene as a second step, has been investigated for eight alkene derivatives. The results indicate that major products from most of the alkenes studied are addition products involving thiocyanate and formate groups. Also minor products of addition of isothiocyanate and thiocyanate groups, and allylic thiocyanates as substitution derivatives, were formed.