bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional to Global Biogenic Isoprene Emission Responses to Changes in Vegetation From 2000 to 2015
Authors: Chen W. H. , Guenther A. B. , Wang X. M. , Chen Y. H. , Gu D. S. , Chang M. , Zhou S. Z. , Wu L. L. , Zhang Y. Q. 
Published: March 2018

AbstractIsoprene, a dominant biogenic volatile organic compound that is mainly emitted by trees, has a significant impact on the atmospheric chemistry. Regional to global changes in biogenic isoprene emission associated with vegetation variations between 2000 and 2015 were estimated using the MEGAN model with satellite land cover data for inputs in this study. The satellite data estimates of land cover changes were compared to results from previous investigators that have either conducted regional studies or have used lower resolution land cover data. The analysis indicates that tree coverage increases of >5% occurred in 13% of locations including in central China and Europe. In contrast, a decrease of >5% was observed in about 5% of locations, especially in tropical regions. The trends in global tree coverage from 2000 to 2015 resulted in a global isoprene emission decrease of only 1.5%, but there were significant regional variations. Obvious decreases in tree coverage in some tropical areas (e.g., Amazon Basin, Western Africa, Southeast Asia) resulted in a ~10% reduction of regional isoprene emission due to agricultural expansion. Distinct increments of isoprene emission (5–10%) were mainly found in Northeast China and India and were associated with afforestation efforts. Deforestation and afforestation associated with managed plantations does not only affect the total forest coverage but also impacts average isoprene emission capacity, which can result in accelerated isoprene emission variations. Consequently, isoprene variation assessments are needed that not only account for changes in vegetation fractions but also consider the changes in plant species compositions of forests and other landscapes.
Parameterization of Rocket Dust Storms on Mars in the LMD Martian GCM: Modeling Details and Validation
Authors: Wang Chao , Forget François , Bertrand Tanguy , Spiga Aymeric , Millour Ehouarn , Navarro Thomas 
Published: March 2018

AbstractThe origin of the detached dust layers observed by the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter is still debated. Spiga et al. (2013, https://doi.org/10.1002/jgre.20046) revealed that deep mesoscale convective “rocket dust storms” are likely to play an important role in forming these dust layers. To investigate how the detached dust layers are generated by this mesoscale phenomenon and subsequently evolve at larger scales, a parameterization of rocket dust storms to represent the mesoscale dust convection is designed and included into the Laboratoire de Météorologie Dynamique (LMD) Martian Global Climate Model (GCM). The new parameterization allows dust particles in the GCM to be transported to higher altitudes than in traditional GCMs. Combined with the horizontal transport by large‐scale winds, the dust particles spread out and form detached dust layers. During the Martian dusty seasons, the LMD GCM with the new parameterization is able to form detached dust layers. The formation, evolution, and decay of the simulated dust layers are largely in agreement with the Mars Climate Sounder observations. This suggests that mesoscale rocket dust storms are among the key factors to explain the observed detached dust layers on Mars. However, the detached dust layers remain absent in the GCM during the clear seasons, even with the new parameterization. This implies that other relevant atmospheric processes, operating when no dust storms are occurring, are needed to explain the Martian detached dust layers. More observations of local dust storms could improve the ad hoc aspects of this parameterization, such as the trigger and timing of dust injection.
Venus Resurfacing Constrained by Geoid and Topography
Authors: King Scott D. 
Published: March 2018

AbstractThe primary explanations for the young crater age of the surface of Venus are progressive volcanic resurfacing and a period of mobile‐lid tectonics. The role of initial conditions, mantle potential temperature, and core potential temperature on Venus surface mobility are explored using 3‐D spherical mantle convection calculations with a lithospheric yield stress that allows the fluid to adopt either a stagnant or mobile lid. The small offset between the center of mass and center of figure (CM‐CF) of Venus is reproduced in calculations that never undergo a period of mobile‐lid convection. The CM‐CF offset has never been used in the evaluation of geodynamic models for Venus. The mobile‐lid calculations have a CM‐CF offset that is four times the observed offset, and the offset increases significantly at the onset of a mobile lid/resurfacing event. Furthermore, the rapid increase in core mantle boundary heat flow that occurs as the cold lithospheric material interacts with the core mantle boundary during a mobile‐lid event is sufficient to power a core dynamo, even in the absence of inner core solidification. The core mantle boundary heat flow decays over 1 Gyr after the cessation of mobile‐lid tectonics. The heat flow never reaches a level that would power a thermally driven dynamo in calculations that do not undergo mobile‐lid convection. The calculations indicate that Venus young surface age is not the result of a mobile‐lid resurfacing event while progressive resurfacing is consistent with the observations.
Underutilized Spaceborne GPS Observations for Space Weather Monitoring
Authors: Zakharenkova Irina , Cherniak Iurii 
Published: March 2018

AbstractMany of currently operated low Earth orbit satellites, in particular Earth observing meteorological missions, are equipped with dual‐frequency Global Positioning System (GPS) receivers with a zenith‐looking antenna for tasks of precise orbit determination and timing. The already existed databases with accumulated raw GPS measurements, as a by‐product of satellite missions, can arouse specific interest for ionospheric and space weather community too. We demonstrate potential possibilities and advantages of involving underutilized spaceborne GPS measurements for Space Weather activity monitoring by specification of storm‐induced ionospheric plasma density irregularities at different altitudinal domain of the topside ionosphere. We have analyzed a dynamical response of the high‐latitude topside ionosphere to the intense geomagnetic storm of 19–21 December 2015 using up‐looking GPS measurements on board Swarm and Meteorological Operational satellite (MetOp) missions, flying at altitudes of ~500 km and ~835 km, respectively. For the first time, GPS observations on board the meteorological mission MetOp were used to reveal an occurrence of plasma irregularities at altitudes above 835 km. Our results demonstrate that during strong geomagnetic storms the intense plasma density irregularities can occur in the topside ionosphere near ~500 km altitude and can be still persisted above 835 km. Joint analysis of the Super Dual Auroral Radar Network global convection patterns, ground‐based GPS total electron content (TEC) observations, and MetOp‐derived topside TEC observations confirmed that plasma irregularities above ~835 km coincided with the plasmaspheric/magnetospheric part of the storm‐enhanced density and the polar tongue of ionization structures, which is the first direct observation of the storm‐enhanced density/tongue of ionization structure in the plasmaspheric TEC.
Riverbed Hydrologic Exchange Dynamics in a Large Regulated River Reach
Authors: Zhou Tian , Bao Jie , Huang Maoyi , Hou Zhangshuan , Arntzen Evan , Song Xuehang , Harding Samuel F. , Titzler P. Scott , Ren Huiying , Murray Christopher J. , Perkins William A. , Chen Xingyuan , Stegen James C. , Hammond Glenn E. , Thorne Paul D. , Zachara John M. 
Published: March 2018

AbstractHydrologic exchange flux (HEF) is an important hydrologic component in river corridors that includes both bidirectional (hyporheic) and unidirectional (gaining/losing) surface water‐groundwater exchanges. Quantifying HEF rates in a large regulated river is difficult due to the large spatial domains, complexity of geomorphologic features and subsurface properties, and the great stage variations created by dam operations at multiple time scales. In this study, we developed a method that combined numerical modeling and field measurements for estimating HEF rates across the riverbed in a 7 km long reach of the highly regulated Columbia River. A high‐resolution computational fluid dynamics (CFD) modeling framework was developed and validated by field measurements and other modeling results to characterize the HEF dynamics across the riverbed. We found that about 85% of the time from 2008 to 2014 the river was losing water with an annual average net HEF rates across the riverbed (Qz) of −2.3 m3 s−1 (negative indicating downwelling). June was the only month that the river gained water, with monthly averaged Qz of 0.8 m3 s−1. We also found that the daily dam operations increased the hourly gross gaining and losing rate over an average year of 8% and 2%, respectively. By investigating the HEF feedbacks at various time scales, we suggest that the dam operations could reduce the HEF at seasonal time scale by decreasing the seasonal flow variations, while also enhance the HEF at subdaily time scale by generating high‐frequency discharge variations. These changes could generate significant impacts on biogeochemical processes in the hyporheic zone.
Normal Faulting in the 1923 Berdún Earthquake and Postorogenic Extension in the Pyrenees
Authors: Stich Daniel , Martín Rosa , Batlló Josep , Macià Ramón , Mancilla Flor de Lis , Morales Jose 
Published: March 2018

AbstractThe 10 July 1923 earthquake near Berdún (Spain) is the largest instrumentally recorded event in the Pyrenees. We recover old analog seismograms and use 20 hand‐digitized waveforms for regional moment tensor inversion. We estimate moment magnitude Mw 5.4, centroid depth of 8 km, and a pure normal faulting source with strike parallel to the mountain chain (N292°E), dip of 66° and rake of −88°. The new mechanism fits into the general predominance of normal faulting in the Pyrenees and extension inferred from Global Positioning System data. The unique location of the 1923 earthquake, near the south Pyrenean thrust front, shows that the extensional regime is not confined to the axial zone where high topography and the crustal root are located. Together with seismicity near the northern mountain front, this indicates that gravitational potential energy in the western Pyrenees is not extracted locally but induces a wide distribution of postorogenic deformation.
Rupture Dynamics of Heterogeneous Frictional Interfaces
Authors: Bayart E. , Svetlizky I. , Fineberg J. 
Published: March 2018

AbstractThe onset of sliding motion is conditional on the propagation of rupture fronts that detach the contacting asperities forming a frictional interface. These ruptures, when propagating over a fault surface, are the most common mechanism for an earthquake. Experimentally, the transition from static to sliding friction takes place when a rupture traverses the entire interface. But ruptures can also arrest before reaching the end of the interface. The determination of the mechanisms responsible for rupture arrest is of particular interest for understanding an earthquake's magnitude selection. Propagating ruptures have been shown to be true shear cracks, driven by singular fields at their tip, and fracture mechanics have been successfully used to describe rupture arrest along homogeneous frictional interfaces. Performing high temporal resolution measurements of the real contact area and strain fields, we demonstrate that the same framework provides an excellent quantitative description of rupture arrest along interfaces with heterogeneous fracture properties and complex stress distributions at a macroscopic scale. This work unravels the different mechanisms responsible for rupture arrest along model laboratory faults. This fracture‐based paradigm opens a window to a wide range of possible consequences for frictional behavior along any two contacting bodies; from the centimeter scale to the scale of natural faults.
Brain‐computer interfaces for post‐stroke motor rehabilitation: a meta‐analysis
Authors: Cervera María A. , Soekadar Surjo R. , Ushiba Junichi , Millán José del R. , Liu Meigen , Birbaumer Niels , Garipelli Gangadhar 
Published: March 2018

AbstractBrain‐computer interfaces (BCIs) can provide sensory feedback of ongoing brain oscillations, enabling stroke survivors to modulate their sensorimotor rhythms purposefully. A number of recent clinical studies indicate that repeated use of such BCIs might trigger neurological recovery and hence improvement in motor function. Here, we provide a first meta‐analysis evaluating the clinical effectiveness of BCI‐based post‐stroke motor rehabilitation. Trials were identified using MEDLINE, CENTRAL, PEDro and by inspection of references in several review articles. We selected randomized controlled trials that used BCIs for post‐stroke motor rehabilitation and provided motor impairment scores before and after the intervention. A random‐effects inverse variance method was used to calculate the summary effect size. We initially identified 524 articles and, after removing duplicates, we screened titles and abstracts of 473 articles. We found 26 articles corresponding to BCI clinical trials, of these, there were nine studies that involved a total of 235 post‐stroke survivors that fulfilled the inclusion criterion (randomized controlled trials that examined motor performance as an outcome measure) for the meta‐analysis. Motor improvements, mostly quantified by the upper limb Fugl‐Meyer Assessment (FMA‐UE), exceeded the minimal clinically important difference (MCID=5.25) in six BCI studies, while such improvement was reached only in three control groups. Overall, the BCI training was associated with a standardized mean difference of 0.79 (95% CI: 0.37 to 1.20) in FMA‐UE compared to control conditions, which is in the range of medium to large summary effect size. In addition, several studies indicated BCI‐induced functional and structural neuroplasticity at a subclinical level. This suggests that BCI technology could be an effective intervention for post‐stroke upper limb rehabilitation. However, more studies with larger sample size are required to increase the reliability of these results.
Coding Cell Micropatterns Through Peptide Inkjet Printing for Arbitrary Biomineralized Architectures
Authors: Guo Jin , Ling Shengjie , Li Wenyi , Chen Ying , Li Chunmei , Omenetto Fiorenzo G. , Kaplan David L. 
Published: March 2018

AbstractWell‐designed micropatterns present in native tissues and organs involve changes in extracellular matrix compositions, cell types and mechanical properties to reflect complex biological functions. However, the design and fabrication of these micropatterns in vitro to meet task‐specific biomedical applications remains a challenge. A de novo design strategy to code and synthesize functional micropatterns is presented to engineer cell alignment through the integration of aqueous‐peptide inkjet printing and site‐specific biomineralization. The inkjet printing provides direct writing of macroscopic biosilica selective peptide‐R5 patterns with micrometer‐scale resolution on the surface of a biopolymer (silk) hydrogel. This is combined with in situ biomineralization of the R5 peptide for site‐specific growth of silica nanoparticles on the micropatterns, avoiding the use of harsh chemicals or complex processing. The functional micropatterned systems are used to align human mesenchymal stem cells and bovine serum albumin. This combination of peptide printing and site‐specific biomineralization provides a new route for developing cost‐effective micropatterns, with implications for broader materials designs.
Functional Carbons Remedy the Shuttling of Polysulfides in Lithium–Sulfur Batteries: Confining, Trapping, Blocking, and Breaking up
Authors: Shi Huifa , Lv Wei , Zhang Chen , Wang Da‐Wei , Ling Guowei , He Yanbing , Kang Feiyu , Yang Quan‐Hong 
Published: March 2018

AbstractCarbon materials are usually used as the sulfur host in rechargeable lithium–sulfur (Li–S) batteries that are considered as promising electrochemical energy storage systems. However, the “shuttling” caused by the soluble lithium polysulfides (LiPSs) formed by the reaction of Li and sulfur causes rapid capacity fade and low sulfur utilization, greatly hindering their practical use. The carbon materials can also be tailored to prevent LiPS shuttling because of their abundant porosity and controllable surface chemical properties, which are divided into four specific functions: confining, trapping, blocking, and breaking up. Confinement means physically confining the LiPSs in pores in the carbon while trapping refers to chemical adsorption on the carbon surface to restrict their diffusion and promote their transformation to insoluble Li2S2/Li2S. Blocking means placing a barrier in the cells to inhibit LiPS diffusion to the anode, while breaking up means decreasing the size of the sulfur moiety to increase its affinity with carbons. The advantages and disadvantages of functional carbons in relation to these four functions are summarized and the specific ways to achieve them are highlighted. The design of advanced carbons with synergistic functions is discussed and some perspectives on the future development of carbons in Li–S batteries are given.
Excitonic Properties of Chemically Synthesized 2D Organic–Inorganic Hybrid Perovskite Nanosheets
Authors: Zhang Qi , Chu Leiqiang , Zhou Feng , Ji Wei , Eda Goki 
Published: March 2018

Abstract2D organic–inorganic hybrid perovskites (OIHPs) represent a unique class of materials with a natural quantum‐well structure and quasi‐2D electronic properties. Here, a versatile direct solution‐based synthesis of mono‐ and few‐layer OIHP nanosheets and a systematic study of their electronic structure as a function of the number of monolayers by photoluminescence and absorption spectroscopy are reported. The monolayers of various OIHPs are found to exhibit high electronic quality as evidenced by high quantum yield and negligible Stokes shift. It is shown that the ground exciton peak blueshifts by ≈40 meV when the layer thickness reduces from bulk to monolayer. It is also shown that the exciton binding energy remains effectively unchanged for (C6H5(CH2)2NH3)2PbI4 with the number of layers. Similar trends are observed for (C4H9NH3)2PbI4 in contrast to the previous report. Further, the photoluminescence lifetime is found to decrease with the number of monolayers, indicating the dominant role of surface trap states in nonradiative recombination of the electron–hole pairs.
Synthesis of Monofluoromethylthioesters from Aldehydes
Authors: Guo Shi‐Huan , Wang Meng‐Yue , Pan Gao‐Fei , Zhu Xue‐Qing , Gao Ya‐Ru , Wang Yong‐Qiang 
Published: March 2018

AbstractA direct and efficient approach to the synthesis of monofluoromethylthioesters from aldehydes has been developed. The synthetic method features mild reaction conditions, good tolerance of functional groups, a broad substrate scope, and especially no metal involved in the reaction. The approach has the potential to be an important tool for the late‐stage functionalization of advanced synthetic intermediates, and may find many applications in medicinal chemistry.magnified image
Mechanochemical Cobalt‐Catalyzed C−H Bond Functionalizations by Ball Milling
Authors: Cheng Hanchao , Hernández José G. , Bolm Carsten 
Published: March 2018

AbstractBall milling techniques have been applied in the development of a mechanosynthesis of [Cp*Co(CO)I2], which proved highly efficient as catalyst in mechanochemical C−H bond amidations of indoles in a mixer ball mill. A wide range of amidated products is obtained in excellent yields. Compared to the solution‐based methods, the procedure opens a more feasible and environmentally‐friendly access to both the cobalt(III) catalyst and 2‐amidated indoles.magnified image
Vertically Oriented MoS2 with Spatially Controlled Geometry on Nitrogenous Graphene Sheets for High‐Performance Sodium‐Ion Batteries
Authors: Li Ping , Jeong Jong Yeob , Jin Bingjun , Zhang Kan , Park Jong Hyeok 
Published: March 2018

AbstractInspired by the great success of graphite in lithium‐ion batteries, anode materials that undergo an intercalation mechanism are considered to provide stable and reversible electrochemical sodium‐ion storage for sodium‐ion battery (SIB) applications. Though MoS2 is a promising 2D material for SIBs, it suffers from deformation of its layered structure during repeated intercalation of Na+, resulting in undesirable electrochemical behaviors. In this study, vertically oriented MoS2 on nitrogenous reduced graphene oxide sheets (VO‐MoS2/N‐RGO) is presented with designed spatial geometries, including sheet density and height, which can deliver a remarkably high reversible capacity of 255 mA h g−1 at a current density of 0.2 A g−1 and 245 mA h g−1 at a current density of 1 A g−1, with a total fluctuation of 5.35% over 1300 cycles. These results are superior to those obtained with well‐developed hard carbon structures. Furthermore, a SIB full cell composed of the optimized VO‐MoS2/N‐RGO anode and a Na2V3(PO4)3 cathode reaches a specific capacity of 262 mA h g−1 (based on the anode mass) during 50 cycles, with an operated voltage range of 2.4 V, demonstrating the potentially rewarding SIB performance, which is useful for further battery development.
Liquid Norbornadiene Photoswitches for Solar Energy Storage
Authors: Dreos Ambra , Wang Zhihang , Udmark Jonas , Ström Anna , Erhart Paul , Börjesson Karl , Nielsen Mogens Brøndsted , Moth‐Poulsen Kasper 
Published: March 2018

AbstractDue to high global energy demands, there is a great need for development of technologies for exploiting and storing solar energy. Closed cycle systems for storage of solar energy have been suggested, based on absorption of photons in photoresponsive molecules, followed by on‐demand release of thermal energy. These materials are called solar thermal fuels (STFs) or molecular solar thermal (MOST) energy storage systems. To achieve high energy densities, ideal MOST systems are required either in solid or liquid forms. In the case of the latter, neat high performing liquid materials have not been demonstrated to date. Here is presented a set of neat liquid norbornadiene derivatives for MOST applications and their characterization in toluene solutions and neat samples. Their synthesis is in most cases based on solvent‐free Diels‐Alder reactions, which easily and efficiently afford a range of compounds. The shear viscosity of the obtained molecules is close to that of colza oil, and they can absorb up to 10% of the solar spectrum with a measured energy storage density of up to 577 kJ/kg corresponding to 152 kJ mol–1 (calculated 100 kJ mol–1). These findings pave the way towards implementation of liquid norbornadienes in closed cycle energy storage technologies.