bluuebunny/crossref_metadata_2025 huggingface dataset:
Caracterização da ictiofauna do rio Santa Catarina (Bacia do São Francisco) no município de Vazante, Minas Gerais
Authors: Amorim Nathan Pereira Lima , Giongo Patrícia , Belei Frederico , Sampaio Wagner Martins Santana
Published: June 2016

A bacia hidrográfica do rio São Francisco é a terceira maior em extensão do Brasil. O Rio Paracatu é um dos principais contribuintes do rio São Francisco. O rio Santa Catarina é afluente esquerdo do rio Paracatu, sendo o principal rio presente no município de Vazante, em Minas Gerais. A Ictiofauna da bacia do São Francisco é representada por cerca de 158 espécies de água doce, sendo as famílias Characidae, Loricariidae, Rivulidae e Anostomidae as mais diversificadas. Na região do rio Santa Catarina no município de Vazante (MG) as atividades ligadas à mineração representa a principal atividade econômica da região, porém causa vários tipos de impactos ambientais aos ecossistemas aquáticos. O presente trabalho busca caracterizar a área do Rio Santa Catarina, no município de Vazante, Minas Gerais, e desta forma propor medidas de conservação da ictiofauna da bacia do Rio Santa Catarina. Foram capturados 177 indivíduos. Estes estão distribuídos em 61 espécies, 45 gêneros, 22 famílias e 6 ordens. O rio Santa Catarina apresenta inúmeros habitats que são essenciais para manutenção da biodiversidade aquática da bacia do rio São Francisco, como veredas, dolinas naturais e rios intermitentes que apresentam peixes de vida restrita e ameaçados de extinção, além de se apresentar como importante rota migratória para o rio Paracatu um dos principais afluentes do rio São Francisco em Minas Gerais.

 

10.7902/ecb.v4i1.53
Ictiofauna do baixo rio Manhuaçu (Bacia do baixo rio Doce)
Authors: Marques Bruno , Belei Frederico , Sampaio Wagner Martins Santana
Published: June 2016

A ictiofauna neotropical se destaca por ser a maior e mais diversificada do planeta uma vez que está inserida no maior sistema fluvial do mundo. Nesse contexto é inserida a bacia do rio Doce a qual é subdividida em três seções: alto, médio e baixo curso. Com o objetivo de se avaliar diversidade da Ictiofauna do rio Manhuaçu, foram estabelecidos dois pontos amostrais. Em cada área de amostragem foi utilizado um conjunto de dez redes de espera, dois espinheis com 10 anzóis, tarrafas, arrastão e pesca elétrica. Durante o período de amostragem foram capturados 207 exemplares distribuídos em 29 espécies, 6 ordens e 14 famílias. Registros anteriores apresentaram uma menor diversidade de peixes para o rio Manhuaçu. Para o médio rio Doce são descrita 70 espécies e o presente estudo representa 41% dessas espécies, revelando a importância do rio Manhuaçu para a bacia do médio e baixo rio Doce.

 

DOI: 10.7902/ecb.v4i1.63
ASSEMBLEIAS DE PEIXES EM IGARAPÉS DE TERRA FIRME EM DUAS SUB-BACIAS DO MÉDIO RIO MADEIRA, BRASIL
Authors: Anjos Marcelo Rodrigues dos , Manzatto Ângelo Gilberto , Machado Nadja Gomes
Published: June 2016

A bacia Amazônica abriga a maior diversidade de peixes de água doce do mundo. O objetivo deste estudo foi analisar as assembleias de peixes em igarapés de terra firme em duas sub-bacias do Médio Rio Madeira. O estudo foi realizado em duas sub-bacias no Médio Rio Madeira localizadas em terras indígenas. Foram coletados 475 indivíduos, distribuídos em 55 espécies. As curvas do coletor e de rarefação indicam esforço amostral satisfatório. A ordem Characiformes foi a mais abundante. A espécie mais abundante foi Potamorhina latior e a mais amplamente distribuída foi Crenicichla lenticulata. A cor da água estruturou a assembleia de peixes em igarapés na área de estudo com maior diversidade de espécies em igarapés de água preta. Diferenças entre águas pretas, brancas e claras são óbvias, mas mais estudos sobre assembleias de peixes nestes ambientes da bacia Amazônica são necessários.
Basin‐wide N2 fixation in the deep waters of the Mediterranean Sea
Authors: Benavides Mar , Bonnet Sophie , Hernández Nauzet , Martínez‐Pérez Alba María , Nieto‐Cid Mar , Álvarez‐Salgado Xosé Antón , Baños Isabel , Montero María F. , Mazuecos Ignacio P. , Gasol Josep M. , Osterholz Helena , Dittmar Thorsten , Berman‐Frank Ilana , Arístegui Javier
Published: June 2016

Recent findings indicate that N2 fixation is significant in aphotic waters, presumably due to heterotrophic diazotrophs depending on organic matter for their nutrition. However, the relationship between organic matter and heterotrophic N2 fixation remains unknown. Here we explore N2 fixation in the deep chlorophyll maximum and underneath deep waters across the whole Mediterranean Sea and relate it to organic matter composition, characterized by optical and molecular methods. Our N2 fixation rates were in the range of those previously reported for the euphotic zone of the Mediterranean Sea (up to 0.43 nmol N L−1 d−1) and were significantly correlated to the presence of relatively labile organic matter with fluorescence and molecular formula properties representative for peptides and unsaturated aliphatics and associated with the presence of more oxygenated ventilated water masses. Finally, and despite that the aphotic N2 fixation contributes largely to total water column diazotrophic activity (>50%), its contribution to overall nitrogen inputs to the basin is negligible (<0.5%).
Enzyme‐level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean
Authors: Kemeny P. C. , Weigand M. A. , Zhang R. , Carter B. R. , Karsh K. L. , Fawcett S. E. , Sigman D. M.
Published: June 2016

In the Southern Ocean, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3−) have been used to investigate NO3− assimilation and N cycling in the summertime period of phytoplankton growth, both today and in the past. However, recent studies indicate the significance of processes in other seasons for producing the annual cycle of N isotope changes. This study explores the impact of fall conditions on the 15N/14N (δ15N) and 18O/16O (δ18O) of NO3− and nitrite (NO2−) in the Pacific Antarctic Zone using depth profiles from late summer/fall of 2014. In the mixed layer, the δ15N and δ18O of NO3− + NO2− increase roughly equally, as expected for NO3− assimilation; however, the δ15N of NO3−‐only (measured after NO2− removal) increases more than does NO3−‐only δ18O. Differencing indicates that NO2− has an extremely low δ15N, often < −70‰ versus air. These observations are consistent with the expression of an equilibrium N isotope effect between NO3− and NO2−, likely due to enzymatic NO3−‐NO2− interconversion. Specifically, we propose reversibility of the nitrite oxidoreductase (NXR) enzyme of nitrite oxidizers that, having been entrained from the subsurface during late summer mixed layer deepening, are inhibited by light. Our interpretation suggests a role for NO3−‐NO2− interconversion where nitrifiers are transported into environments that discourage NO2− oxidation. This may apply to surface regions with upwelling, such as the summertime Antarctic. It may also apply to oxygen‐deficient zones, where NXR‐catalyzed interconversion may explain previously reported evidence of NO2− oxidation.
Initial deflection of middle‐latitude Pi2 pulsations in the premidnight sector: Remote detection of oscillatory upward field‐aligned current at substorm onset
Authors: Uozumi Teiji , Yoshikawa A. , Ohtani S. , Imajo S. , Baishev D. G. , Moiseev A. V. , Yumoto K.
Published: June 2016

In this study, we examined middle‐ and low‐latitude Pi2 events to address the following two issues regarding the well‐known substorm current wedge (SCW) model for Pi2 pulsations: (1) the center of the SCW, which is estimated using the Pi2 polarization pattern, is not always collocated with that determined using the magnetic bay pattern; and (2) although ideally Pi2 hodograms would be linear, they tend to become circular. In this study, auroral breakup events were identified from Polar Ultraviolet Imager data. We assumed that the ionospheric footprint of the upward field‐aligned current (FAC) in each event was located at the position of the auroral breakup and subsequently calculated the signature of the magnetic variation at the middle‐latitude station Zyryanka (ZYK; GMLAT = 59.6°) that was generated by the upward FAC. In order to examine the magnetic effects of the upward FAC, we selected Pi2 events that were observed when ZYK was located on the duskward side of the auroral breakup location. A total of 112 events were selected and analyzed in this study. It was found that the location of the upward FAC of the SCW could be estimated more accurately by using an azimuth value predicted based on the initial deflection of the middle‐latitude Pi2. Our results suggest that the circular shapes of Pi2 polarization curves are caused by the delayed driven Alfvénic waves that are superimposed on the geomagnetic northward components of SCW oscillations.
Assessment of a numerical model to reproduce event‐scale erosion and deposition distributions in a braided river
Authors: Williams R. D. , Measures R. , Hicks D. M. , Brasington J.
Published: June 2016

Numerical morphological modeling of braided rivers, using a physics‐based approach, is increasingly used as a technique to explore controls on river pattern and, from an applied perspective, to simulate the impact of channel modifications. This paper assesses a depth‐averaged nonuniform sediment model (Delft3D) to predict the morphodynamics of a 2.5 km long reach of the braided Rees River, New Zealand, during a single high‐flow event. Evaluation of model performance primarily focused upon using high‐resolution Digital Elevation Models (DEMs) of Difference, derived from a fusion of terrestrial laser scanning and optical empirical bathymetric mapping, to compare observed and predicted patterns of erosion and deposition and reach‐scale sediment budgets. For the calibrated model, this was supplemented with planform metrics (e.g., braiding intensity). Extensive sensitivity analysis of model functions and parameters was executed, including consideration of numerical scheme for bed load component calculations, hydraulics, bed composition, bed load transport and bed slope effects, bank erosion, and frequency of calculations. Total predicted volumes of erosion and deposition corresponded well to those observed. The difference between predicted and observed volumes of erosion was less than the factor of two that characterizes the accuracy of the Gaeuman et al. bed load transport formula. Grain size distributions were best represented using two φ intervals. For unsteady flows, results were sensitive to the morphological time scale factor. The approach of comparing observed and predicted morphological sediment budgets shows the value of using natural experiment data sets for model testing. Sensitivity results are transferable to guide Delft3D applications to other rivers.
Geodetically constrained models of viscoelastic stress transfer and earthquake triggering along the North Anatolian fault
Authors: DeVries Phoebe M. R. , Krastev Plamen G. , Meade Brendan J.
Published: June 2016

Over the past 80 years, 8 MW > 6.7 strike‐slip earthquakes west of 40° longitude have ruptured the North Anatolian fault (NAF) from east to west. The series began with the 1939 Erzincan earthquake in eastern Turkey, and the most recent 1999 MW = 7.4 Izmit earthquake extended the pattern of ruptures into the Sea of Marmara in western Turkey. The mean time between seismic events in this westward progression is 8.5 ± 11 years (67% confidence interval), much greater than the timescale of seismic wave propagation (seconds to minutes). The delayed triggering of these earthquakes may be explained by the propagation of earthquake‐generated diffusive viscoelastic fronts within the upper mantle that slowly increase the Coulomb failure stress change (
CFS) at adjacent hypocenters. Here we develop three‐dimensional stress transfer models with an elastic upper crust coupled to a viscoelastic Burgers rheology mantle. Both the Maxwell (ηM = 4 × 1018−1 × 1019 Pa s) and Kelvin (ηK = 1 × 1018−1 × 1019 Pa s) viscosities are constrained by studies of geodetic observations before and after the 1999 Izmit earthquake. We combine this geodetically constrained rheological model with the observed sequence of large earthquakes since 1939 to calculate the time evolution of
CFS changes along the North Anatolian fault due to viscoelastic stress transfer. Apparent threshold values of mean
CFS at which the earthquakes in the eight decade sequence occur are between ∼0.02 to ∼3.15 MPa and may exceed the magnitude of static
CFS values by as much as 177%. By 2023, we infer that the mean time‐dependent stress change along the northern NAF strand in the Marmara Sea near Istanbul, which may have previously ruptured in 1766, may reach the mean apparent time‐dependent stress thresholds of the previous NAF earthquakes.
The electric wind of Venus: A global and persistent “polar wind”‐like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions
Authors: Collinson Glyn A. , Frahm Rudy A. , Glocer Alex , Coates Andrew J. , Grebowsky Joseph M. , Barabash Stas , Domagal‐Goldman Shawn D. , Fedorov Andrei , Futaana Yoshifumi , Gilbert Lin K. , Khazanov George , Nordheim Tom A. , Mitchell David , Moore Thomas E. , Peterson William K. , Winningham John D. , Zhang Tielong L.
Published: June 2016

Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an “ambipolar” electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water‐group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an “electric wind” must be considered when studying the evolution and potential habitability of any planet in any star system.
Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics
Authors: Park Jae‐Hyoung , Chang Kyung‐Il , Nam SungHyun
Published: June 2016

A 6 year long current measurement at a buoy station off the middle east coast of Korea reveals an equatorward reversal of coastal current in summer opposing poleward local wind stress and offshore boundary current. The current reversal extends about 40 km offshore from the coast and is concurrent with warming and freshening of water column. Estimates of the depth‐averaged alongshore momentum balance suggest a major balance between the alongshore pressure gradient and the lateral friction. Sources of the pressure gradient for the summertime current reversal are identified as the alongshore buoyancy gradient driven by the wind curl gradient and the prevalence of warmer and lower salinity water in the north. Alongshore pressure gradient and velocity induced by the wind curl gradient are quantified, which yields the observed seasonal current reversal.
Evidence for the release of long‐term tectonic strain stored in continental interiors through intraplate earthquakes
Authors: Craig T. J. , Calais E. , Fleitout L. , Bollinger L. , Scotti O.
Published: June 2016

The occurrence of large earthquakes in stable continental interiors challenges the applicability of the classical steady state “seismic cycle” model to such regions. Here we shed new light onto this issue using as a case study the cluster of large reverse faulting earthquakes that occurred in Fennoscandia at 11–9 ka, triggered by the removal of the ice load during the final phase of regional deglaciation. We show that these reverse‐faulting earthquakes occurred at a time when the horizontal strain rate field was extensional, which implies that these events did not release horizontal strain that was building up at the time but compressional strain that had been accumulated and stored elastically in the lithosphere over timescales similar to or longer than a glacial cycle. We argue that the tectonically stable continental lithosphere can store elastic strain on long timescales, the release of which may be triggered by rapid, local transient stress changes caused by surface mass redistribution, resulting in the occurrence of intermittent intraplate earthquakes.
Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake
Authors: Floyd Michael A. , Walters Richard J. , Elliott John R. , Funning Gareth J. , Svarc Jerry L. , Murray Jessica R. , Hooper Andy J. , Larsen Yngvar , Marinkovic Petar , Bürgmann Roland , Johanson Ingrid A. , Wright Tim J.
Published: June 2016

Following earthquakes, faults are often observed to continue slipping aseismically. It has been proposed that this afterslip occurs on parts of the fault with rate‐strengthening friction that are stressed by the main shock, but our understanding has been limited by a lack of immediate, high‐resolution observations. Here we show that the behavior of afterslip following the 2014 South Napa earthquake in California varied over distances of only a few kilometers. This variability cannot be explained by coseismic stress changes alone. We present daily positions from continuous and survey GPS sites that we remeasured within 12 h of the main shock and surface displacements from the new Sentinel‐1 radar mission. This unique geodetic data set constrains the distribution and evolution of coseismic and postseismic fault slip with exceptional resolution in space and time. We suggest that the observed heterogeneity in behavior is caused by lithological controls on the frictional properties of the fault plane.
Potential tropical Atlantic impacts on Pacific decadal climate trends
Authors: Chikamoto Y. , Mochizuki T. , Timmermann A. , Kimoto M. , Watanabe M.
Published: June 2016

The tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere‐ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three‐dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low‐frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.
A Rossby whistle: A resonant basin mode observed in the Caribbean Sea
Authors: Hughes Chris W. , Williams Joanne , Hibbert Angela , Boening Carmen , Oram James
Published: June 2016

We show that an important source of coastal sea level variability around the Caribbean Sea is a resonant basin mode. The mode consists of a baroclinic Rossby wave which propagates westward across the basin and is rapidly returned to the east along the southern boundary as coastal shelf waves. Almost two wavelengths of the Rossby wave fit across the basin, and it has a period of 120 days. The porous boundary of the Caribbean Sea results in this mode exciting a mass exchange with the wider ocean, leading to a dominant mode of bottom pressure variability which is almost uniform over the Grenada, Venezuela, and Colombia basins and has a sharp spectral peak at 120 day period. As the Rossby waves have been shown to be excited by instability of the Caribbean Current, this resonant mode is dynamically equivalent to the operation of a whistle.
Simultaneous storm time equatorward and poleward large‐scale TIDs on a global scale
Authors: Habarulema John Bosco , Katamzi Zama Thobeka , Yizengaw Endawoke , Yamazaki Yosuke , Seemala Gopi
Published: June 2016

We report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground‐based magnetometer observations and available low‐latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.
Assessing the impact of vertical land motion on twentieth century global mean sea level estimates
Authors: Hamlington B. D. , Thompson P. , Hammond W. C. , Blewitt G. , Ray R. D.
Published: June 2016

Near‐global and continuous measurements from satellite altimetry have provided accurate estimates of global mean sea level in the past two decades. Extending these estimates further into the past is a challenge using the historical tide gauge records. Not only is sampling nonuniform in both space and time, but tide gauges are also affected by vertical land motion (VLM) that creates a relative sea level change not representative of ocean variability. To allow for comparisons to the satellite altimetry estimated global mean sea level (GMSL), typically the tide gauges are corrected using glacial isostatic adjustment (GIA) models. This approach, however, does not correct other sources of VLM that remain in the tide gauge record. Here we compare Global Positioning System (GPS) VLM estimates at the tide gauge locations to VLM estimates from GIA models, and assess the influence of non‐GIA‐related VLM on GMSL estimates. We find that the tide gauges, on average, are experiencing positive VLM (i.e., uplift) after removing the known effect of GIA, resulting in an increase of 0.24 ± 0.08 mm yr−1 in GMSL trend estimates from 1900 to present when using GPS‐based corrections. While this result is likely dependent on the subset of tide gauges used and the actual corrections used, it does suggest that non‐GIA VLM plays a significant role in twentieth century estimates of GMSL. Given the relatively short GPS records used to obtain these VLM estimates, we also estimate the uncertainty in the GMSL trend that results from limited knowledge of non‐GIA‐related VLM.
A comparative study of wave‐current interactions over the eastern Canadian shelf under severe weather conditions using a coupled wave‐circulation model
Authors: Wang Pengcheng , Sheng Jinyu
Published: June 2016

A coupled wave‐circulation model is used to examine interactions between surface gravity waves and ocean currents over the eastern Canadian shelf and adjacent deep waters during three severe weather events. The simulated significant wave heights (SWHs) and peak wave periods reveal the importance of wave‐current interactions (WCI) during and after the storm. In two fast‐moving hurricane cases, the maximum SWHs are reduced by more than 11% on the right‐hand side of the storm track and increased by about 5% on the left‐hand side due to different WCI mechanisms on waves on two sides of the track. The dominate mechanisms of the WCI on waves include the current‐induced modification of wind energy input to the wave generation, and current‐induced wave advection and refraction. In the slow‐moving winter storm case, the effect of WCI decreases the maximum SWHs on both sides of the storm track due to different results of the current‐induced wave advection, which is affected greatly by the storm translation speed. The simulated sea surface temperature (SST) cooling induced by hurricanes and SST warming induced by the winter storm are also enhanced (up to 1.2°C) by the WCI mechanisms on circulation and hydrography. The 3D wave forces can affect water columns up to 200 m in all three storm cases. By comparison, the effect of breaking wave‐induced mixing in the ocean upper layer is more important under strong stratification conditions in two hurricane cases than under weak stratification conditions in the winter storm case.
Impact of the Nature of the Side‐Chains on the Polymer‐Fullerene Packing in the Mixed Regions of Bulk Heterojunction Solar Cells
Authors: Wang Tonghui , Ravva Mahesh Kumar , Brédas Jean‐Luc
Published: June 2016

Polymer‐fullerene packing in mixed regions of a bulk heterojunction solar cell is expected to play a major role in exciton‐dissociation, charge‐separation, and charge‐recombination processes. Here, molecular dynamics simulations are combined with density functional theory calculations to examine the impact of nature and location of polymer side‐chains on the polymer‐fullerene packing in mixed regions. The focus is on poly‐benzo[1,2‐b:4,5‐b′]dithiophene‐thieno[3,4‐c]pyrrole‐4,6‐dione (PBDTTPD) as electron‐donating material and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as electron‐accepting material. Three polymer side‐chain patterns are considered: i) linear side‐chains on both benzodithiophene (BDT) and thienopyrroledione (TPD) moieties; ii) two linear side‐chains on BDT and a branched side‐chain on TPD; and iii) two branched side‐chains on BDT and a linear side‐chain on TPD. Increasing the number of branched side‐chains is found to decrease the polymer packing density and thereby to enhance PBDTTPD–PC61 BM mixing. The nature and location of side‐chains are found to play a determining role in the probability of finding PC61BM molecules close to either BDT or TPD. The electronic couplings relevant for the exciton‐dissociation and charge‐recombination processes are also evaluated. Overall, the findings are consistent with the experimental evolution of the PBDTTPD–PC61BM solar‐cell performance as a function of side‐chain patterns.
Atomically Resolved Elucidation of the Electrochemical Covalent Molecular Grafting Mechanism of Single Layer Graphene
Authors: Gearba Raluca I. , Kim Minjung , Mueller Kory M. , Veneman Peter A. , Lee Kayoung , Holliday Bradley J. , Chan Calvin K. , Chelikowsky James R. , Tutuc Emanuel , Stevenson Keith J.
Published: June 2016

Engineering graphene at the atomic level via chemical doping, substrate interactions or lateral confinement opens up avenues for precise tuning of its electronic and magnetic properties. Chemical doping by covalent modification routes using electrochemical tools offers rich opportunities that are yet to be fully explored. The key to controlling graphene's physicochemical properties requires a detailed atomistic understanding of the geometry and mechanism of the covalent attachment process. By employing diaryliodonium salts instead of the commonly used diazonium salts, precise molecular grafting onto epitaxial graphene is achieved. Using atomically resolved imaging via scanning tunneling microscopy it is shown that for single layer, high quality, low defect graphene, the functionalization process is controlled by kinetics rather than thermodynamics in accord with Marcus–Gerisher theory. The predominance of the preferential pairwise attachment of molecular grafts specifically on the same graphene sublattice gives rise to ferromagnetic properties previously observed in nitrophenyl modified graphene. Furthermore, p‐type doping has been quantified by electrical measurements and angle resolved photoelectron spectroscopy. Overall this electrochemical route for precise covalent functionalization of single layer graphene is general and can be straightforwardly extended to other 2D few‐layer confined materials such as transition metal chalcogenides.
Tuning the Surface Electrochemistry by Strained Epitaxial Pt Thin Film Model Electrodes Prepared by Pulsed Laser Deposition
Authors: Temmel Sandra E. , Fabbri Emiliana , Pergolesi Daniele , Lippert Thomas , Schmidt Thomas J.
Published: June 2016

A novel approach for tailoring strained Pt model electrocatalysts using pulsed laser deposition is presented. The physical properties of Pt films grown on single‐crystalline (100)‐ and (111)‐oriented strontium titanate depend significantly on the various deposition parameters (e.g., fluence, temperature, background atmosphere, postannealing, and number of process steps), as revealed by scanning electron microscopy and X‐ray studies. By properly selecting the deposition conditions, thin, epitaxial, and strained (100)‐ and (111)‐oriented Pt films suitable as model electrodes can be prepared. Cyclic voltammetry measurements indicate that the strain in the Pt films changes significantly the Pt surface properties, such as the hydrogen underpotential deposition (Hupd) features. CO oxidation experiments demonstrate that the strain affects strongly also the position of the CO oxidation peak shifting it to more positive potentials. This might be attributed to a modification of the adsorption behavior of oxygenated species on the strained interface. This research clearly highlights the potential of using as‐produced Pt film as model catalysts to study the effect of strain on electrocatalytic reactions while minimizing possible side effects connected to the common preparation methods for strained Pt catalysts, such as alloy formation, alloy leeching, or conductive support contributions.
Plasmonic AgAl Bimetallic Alloy Nanoparticle/Al2O3 Nanocermet Thin Films with Robust Thermal Stability for Solar Thermal Applications
Authors: Gao Junhua , Wang Xiaoyu , Yang Bing , Tu Chengjun , Liang Lingyan , Zhang Hongliang , Zhuge Fei , Cao Hongtao , Zou Yousheng , Yu Ke , Xia Fei , Han Yingying
Published: June 2016

Developing plasmonic materials as cermet composites is desirable for selective solar absorbers. Silver nanoparticles/alumina (Ag‐Al2O3) cermet possesses reasonable resistance to high‐temperature oxidation; however, an inherent long‐range diffusion of Ag element limits their applications at elevated temperatures. In this work, a well‐designed AgAl‐Al2O3 nanocermet, after low‐temperature pretreatment in air, exhibits stable plasmonic absorption feature with negligible degradation at 500 °C for 990 h in nitrogen ambient. Based on this cermet, an Al2O3/low metal volume fraction AgAl‐Al2O3/high metal volume fraction AgAl‐Al2O3/Al2O3/AgAl tandem absorber was successfully constructed, demonstrating a high solar absorptance of ≈95% and a low infrared emittance of ≈11%@673 K after annealing at 500 °C for 1002 h in nitrogen ambient. It is believed that thermal‐induced out‐diffusion of Al atoms from AgAl bimetallic nanoparticles and their consequent oxidation afford an opportunity to generate self‐organized alumina‐capped Ag nanoparticles. The alumina‐capped Ag particles and unalloyed Ag agglomerations are mixed together to form mosaic structure, suppressing the long‐distance diffusion of active Ag and wild growth of particle agglomerations so as to guarantee the microstructural integrity and plasmon absorption stability. These results demonstrate that the proposed AgAl‐Al2O3‐based solar absorber is remarkably promising to be used in high‐temperature solar thermal conversion.
Watchband‐Like Supercapacitors with Body Temperature Inducible Shape Memory Ability
Authors: Liu Lingyang , Shen Baoshou , Jiang Dan , Guo Ruisheng , Kong Lingbin , Yan Xingbin
Published: June 2016

Smart watches have gained worldwide popularity because they can integrate diverse functions all in one. However, their energy storage devices currently being used are placed in the watches, and this design seriously limited the energy support ability and the future boost space. Herein, for the first time, a strategy to integrate energy storage device with watchband is put forward, which is realized by the preparation of watchband‐like solid‐state supercapacitors using graphene coated on TiNi alloy flake as the negative electrode, ultrathin MnO2/Ni film as the positive electrode, and different gel electrolytes as the separator. Statical and dynamical bending tests both verify that the as‐fabricated devices have excellent electrochemical performance reliability during bending process. The devices also exhibit the distinctive shape memory ability owing to the use of TiNi shape memory alloy. As a state of the art, such a watchband‐like supercapacitor is connected with an electronic watch to show its potential application. Interestingly, this “watchband” can not only support power to the watch, but also can maintain the shape memory property which can be automatically induced by touching it with the human wrist. In addition, it exhibits excellent biocompatibility. Thus, the smart supercapacitor is qualified for a promising candidate for the next‐generation smart watches.
Dose–response between pedometer assessed physical activity, functional fitness, and fatness in healthy adults aged 50–80 years
Authors: Duncan Michael J. , Minatto Giseli , Wright Sheila Leddington
Published: June 2016

Objectives

This study examined dose–response relationships of walking with multiple aspects of physical function and measures of body fatness in apparently healthy, independent adults aged 50–80 years.

Methods

201 adults (81 male, 120 female) aged 50–80 years underwent assessment of body mass index (BMI), body fatness, waist circumference (WC) and 6 measures of functional fitness. Sealed pedometery, worn over 7 days, was used to determine physical activity (PA). PA was categorized into three groups (low = 2,501–5,000; medium = 5,001–7,500; and high=>7,501 steps/day).

Results

Results from a series of 2 (gender) × 3 (PA dose) way analysis of covariance (ANCOVA), controlling for age, indicated dose–response effects of PA for all functional fitness tests where participants classed as high PA had higher scores for arm curl, chair stand, 6 minute walk, back scratch, and sit and reach and lower scores for the timed up and go test compared to those classed as low and medium PA. There were also significant main effects for PA dose for BMI, WC, and body fat %. Those classed as low PA had significantly higher BMI, WC and body fatness compared to those classed as medium and high PA.

Conclusions

This study shows a positive dose–response trend whereby as an individual undertakes more daily steps (based on previously established step‐count groups), multiple aspects of functionality increase and anthropometric markers of overweight and obesity decrease. Am. J. Hum. Biol., 2016. © 2016 Wiley Periodicals, Inc. Am. J. Hum. Biol. 28:890–894, 2016. © 2016Wiley Periodicals, Inc.
In vivo cortical spreading pattern of tau and amyloid in the Alzheimer disease spectrum
Authors: Cho Hanna , Choi Jae Yong , Hwang Mi Song , Kim You Jin , Lee Hye Mi , Lee Hye Sun , Lee Jae Hoon , Ryu Young Hoon , Lee Myung Sik , Lyoo Chul Hyoung
Published: June 2016

Objective

To determine the in vivo cortical spreading pattern of tau and amyloid and to establish positron emission tomography (PET) image‐based tau staging in the Alzheimer disease (AD) spectrum.

Methods

We included 195 participants (53 AD, 52 amnestic mild cognitive impairment [MCI], 23 nonamnestic MCI, and 67 healthy controls) who underwent 2 PET scans (18F‐florbetaben for amyloid‐β and 18F‐AV‐1451 for tau). We assumed that regions with earlier appearances of pathology may show increased binding in a greater number of participants and acquired spreading order of tau accumulation by sorting the regional frequencies of involvement. We classified each participant into image‐based tau stage based on the Z score of the composite region for each stage.

Results

Tau accumulation was most frequently observed in the medial temporal regions and spread stepwise to the basal and lateral temporal, inferior parietal, posterior cingulate, and other association cortices, and then ultimately to the primary cortical regions. In contrast, amyloid accumulation was found with similar frequency in the diffuse neocortical areas and then finally spread to the medial temporal regions. The image‐based tau stage correlated with the general cognitive status, whereas cortical thinning was found only in the advanced tau stages: medial temporal region in stage V and widespread cortex in stage VI.

Interpretation

Our PET study replicated postmortem spreading patterns of tau and amyloid‐β pathologies. Unlike the diffuse accumulation of amyloid throughout the neocortex, tau spreading occurred in a stepwise fashion through the networks. Image‐based tau staging may be useful for the objective assessment of AD progression. Ann Neurol 2016;80:247–258
Allosterically Regulated Phosphatase Activity from Peptide–PNA Conjugates Folded Through Hybridization
Authors: Machida Takuya , Dutt Som , Winssinger Nicolas
Published: June 2016

The importance of spatial organization in short peptide catalysts is well recognized. We synthesized and screened a library of peptides flanked by peptide nucleic acids (PNAs) such that the peptide would be constrained in a hairpin loop upon hybridization. A screen for phosphatase activity led to the discovery of a catalyst with >25‐fold rate acceleration over the linear peptide. We demonstrated that the hybridization‐enforced folding of the peptide is necessary for activity, and designed a catalyst that is allosterically controlled using a complementary PNA sequence.
Fast‐Geomimicking using Chemistry in Supercritical Water
Authors: Dumas Angela , Claverie Marie , Slostowski Cédric , Aubert Guillaume , Careme Cristel , Le Roux Christophe , Micoud Pierre , Martin François , Aymonier Cyril
Published: June 2016

Herein we introduce a powerful and fast method to produce nanominerals using a bottom up approach. The supercritical hydrothermal flow synthesis is exploited to produce model nanominerals by mimicking natural environments at high temperatures under pressure. This innovative concept is demonstrated with the talc synthesis; this represents a major technical breakthrough since it allows decreasing the mineral‐synthesis time from tens of hours to tens of seconds. Through this example, we show these nanominerals exhibit new crystal‐chemistry signals and new properties. This approach provides a means to reproduce the early stages of formation of minerals in different natural environments from sedimentary environments (low temperature and pressure) to hydrothermal/metamorphic environments (high temperature and high pressure).
The Uranyl Cation as a Visible‐Light Photocatalyst for C(sp3)−H Fluorination
Authors: West Julian G. , Bedell T. Aaron , Sorensen Erik J.
Published: June 2016

The fluorination of unactivated C(sp3)−H bonds remains a desirable and challenging transformation for pharmaceutical, agricultural, and materials scientists. Previous methods for this transformation have used bench‐stable fluorine atom sources; however, many still rely on the use of UV‐active photocatalysts for the requisite high‐energy hydrogen atom abstraction event. Uranyl nitrate hexahydrate is described as a convenient, hydrogen atom abstraction catalyst that can mediate fluorinations of certain alkanes upon activation with visible light.
C‐Propargylation Overrides O‐Propargylation in Reactions of Propargyl Chloride with Primary Alcohols: Rhodium‐Catalyzed Transfer Hydrogenation
Authors: Liang Tao , Woo Sang Kook , Krische Michael J.
Published: June 2016

The canonical SN2 behavior displayed by alcohols and activated alkyl halides in basic media (O‐alkylation) is superseded by a pathway leading to carbinol C‐alkylation under the conditions of rhodium‐catalyzed transfer hydrogenation. Racemic and asymmetric propargylations are described.
Boosting Photocatalytic Hydrogen Production of a Metal–Organic Framework Decorated with Platinum Nanoparticles: The Platinum Location Matters
Authors: Xiao Juan‐Ding , Shang Qichao , Xiong Yujie , Zhang Qun , Luo Yi , Yu Shu‐Hong , Jiang Hai‐Long
Published: June 2016

Improving the efficiency of electron–hole separation and charge‐carrier utilization plays a central role in photocatalysis. Herein, Pt nanoparticles of ca. 3 nm are incorporated inside or supported on a representative metal–organic framework (MOF), UiO‐66‐NH2, denoted as Pt@UiO‐66‐NH2 and Pt/UiO‐66‐NH2, respectively, for photocatalytic hydrogen production via water splitting. Compared with the pristine MOF, both Pt‐decorated MOF nanocomposites exhibit significantly improved yet distinctly different hydrogen‐production activities, highlighting that the photocatalytic efficiency strongly correlates with the Pt location relative to the MOF. The Pt@UiO‐66‐NH2 greatly shortens the electron‐transport distance, which favors the electron–hole separation and thereby yields much higher efficiency than Pt/UiO‐66‐NH2. The involved mechanism has been further unveiled by means of ultrafast transient absorption and photoluminescence spectroscopy.
Miscibility, morphology, structure, and properties of porous cellulose–soy protein isolate hybrid hydrogels
Authors: Zheng Kaiwen , Zhang Junying , Cheng Jue
Published: June 2016

Porous hybrid hydrogels were fabricated by mixing cellulose (CEL) and soy protein isolate (SPI) solutions, followed by crosslinking with epichlorohydrin. Their miscibility, morphology, structure, and properties were investigated by wide‐angle X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, dynamic mechanical analysis, rheological measurement, and swelling tests. The results show that CEL performed as a “scaffold” of pore walls and contributed to the good mechanical properties, while SPI performed the role of an “extender” of pore size and was responsible for the high water absorbency. The incorporation of CEL (stiff chains) and SPI (hydrophilic groups) in the hybrid hydrogel constructed the porous structure. This work provides a method for the fabrication of hydrogels with porous structure through the combination of a stiff material as a “scaffold” and a hydrophilic material as an “extender.” © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43853.
Polymeric piezoelectric fiber with metal core produced by electrowetting‐aided dry spinning method
Authors: Liu Weiting , Chen Ran , Ruan Xiaodong , Fu Xin
Published: June 2016

An electrowetting‐aided dry spinning method is developed to produce morphologically stable polymeric piezoelectric fibers with a metal core covered by a beta‐phase poly(vinylidene fluoride) [or poly(vinylidene‐trifluoroethylene)] layer. Each fiber consists of a 100 μm copper core (enameled with 6 μm polyester‐imide), a 3–10 μm piezoelectric layer, and a sputtered 100 nm gold electrode. The morphological properties of the fibers are analyzed with scanning electron microscopy, X‐ray diffraction, and a step profiler. The piezoelectric properties are tested in a vibration‐detecting application. Both morphological observation and piezoelectric testing demonstrate that the electrowetting‐aided dry spinning helps in forming high‐quality polymeric piezoelectric fibers. Moreover, this method can also be applied in different fabrications, where adhesion between a liquid and solid surface needs to be enhanced. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43968.
Fragment Discovery for the Design of Nitrogen Heterocycles as Mycobacterium tuberculosis Dihydrofolate Reductase Inhibitors
Authors: Shelke Rupesh U. , Degani Mariam S. , Raju Archana , Ray Mukti Kanta , Rajan Mysore G. R.
Published: June 2016

Fragment‐based drug design was used to identify Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitors. Screening of ligands against the Mtb DHFR enzyme resulted in the identification of multiple fragment hits with IC50 values in the range of 38–90 μM versus Mtb DHFR and minimum inhibitory concentration (MIC) values in the range of 31.5–125 μg/mL. These fragment scaffolds would be useful for anti‐tubercular drug design.
Mechanistic Insight into the Copper‐Catalyzed Regiodivergent Silacarboxylation of Allenes with CO2
Authors: Yuan Ruming , Hu Rong , Fu Gang
Published: June 2016

DFT calculations were performed to investigate the detailed reaction mechanisms in the copper‐catalyzed regiodivergent silacarboxylation of allenes. According to our calculations, the catalysis would bifurcate at the allene silylcupration step, followed by CO2 insertion, eventually leading to the carboxylated vinylsilane or allylsilane products. The gaps between the two silylcupration barriers were predicted to be −2.3, −0.4, and 2.2 kcal mol−1 when using (rac)‐Me‐DuPhos, dcpe, and PCy3 (+H2O) as the ligands, which nicely accounted for the experimental vinylsilane/allylsilane ratios of 93:7, 50:50, and 15:85, respectively. By means of transition‐state‐energy decomposition, we found that the energy penalty of catalyst deformation into its transition‐state geometry was the key factor in determining the direction of the reaction. The switchable regioselectivity by using different P ligands could be ascribed to structural changes of the Cu−Si and Cu−P bonds during the silylcupration process.
Tuning O2 Reactivity through Synergistic Photo/Copper Catalysis: Direct Synthesis of 4‐Aryl tetralones via Cyclodimerization–Oxygenation of Styrenes
Authors: Zhang Xu , Yi Hong , Luo Yi , Lei Aiwen
Published: June 2016

A transformation is presented that enables chemists to construct 4‐aryl tetralones via visible‐light‐induced cyclodimerization–oxygenation of styrene under very mild conditions. Adding a catalytic amount of CuOAc obviously improves the yield. A mechanistic study reveals that the photoredox catalyst played the role of activating O2 while Cu affected the reactivity of reactive oxygen species (ROS).
Simultaneous evaluation of substrate‐dependent CYP3A inhibition using a CYP3A probe substrates cocktail
Authors: Lee Eunyoung , Shon Jong Cheol , Liu Kwang‐Hyeon
Published: June 2016

Cytochrome P450 (P450) 3A (CYP3A) is an enzyme responsible for the metabolism of therapeutic drugs such as midazolam, nifedipine, testosterone and triazolam. It is involved in 40% of all cases of P450‐mediated metabolism of marketed drugs. Therefore, it is important to evaluate the CYP3A‐mediated drug interaction potential of new chemical entities (NCEs). In the past, one P450 isoform‐specific probe substrate has been used at a time to evaluate the degree of inhibition of P450 isoforms by using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). However, CYP3A enzymes have been shown to have a multi‐substrate binding site. Therefore, multiple CYP3A substrates should be used to evaluate precisely the drug interaction potential of NCEs with the enzyme CYP3A. In this study, a method of screening NCEs for their potential to inhibit by CYP3A enzyme activity was developed. It involves the employment of a CYP3A substrate cocktail (including midazolam, testosterone and nifedipine). The concentration of each CYP3A probe substrate in vitro was optimized (0.1 μm for midazolam, 2 μm for testosterone and 2 μm for nifedipine) to minimize mutual drug interactions among probe substrates. The method was validated by comparing inhibition data obtained from the incubation of CYP3A with each individual substrate with data from incubation with a cocktail of all three substrates. The CYP3A inhibition profiles from the substrate cocktail approach were similar to those from the individual substrates approach. This new method could be an effective tool for the robust and accurate screening of the CYP3A inhibition potential of NCEs in drug discovery. Copyright © 2016 John Wiley & Sons, Ltd.