bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of the Proton Aurora on Mars With SPICAM on Board Mars Express
Authors: Ritter B. , Gérard J.‐C. , Hubert B. , Rodriguez L. , Montmessin F. 
Published: December 2017

AbstractWe report observations of the proton aurora at Mars, obtained with the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet spectrograph on board Mars Express between 2004 and 2011. This is a third type of UV aurora that is discovered on Mars, in addition to the discrete and diffuse nightside aurora. It is observed only on the dayside as it is produced by the direct interaction of solar wind protons with the upper atmosphere. The auroral signature is an enhancement of the Lyman‐α emission in the order of a few kilorayleighs. The proton aurora features peak emissions around 120 to 150 km. From the full SPICAM database, limb observations have been investigated and six clear cases have been found. We identify either coronal mass ejections and/or corotating interaction regions as triggers for each of these events.
The Global Signature of Ocean Wave Spectra
Authors: Portilla‐Yandún Jesús 
Published: December 2017

AbstractA global atlas of ocean wave spectra is developed and presented. The development is based on a new technique for deriving wave spectral statistics, which is applied to the extensive ERA‐Interim database from European Centre of Medium‐Range Weather Forecasts. Spectral statistics is based on the idea of long‐term wave systems, which are unique and distinct at every geographical point. The identification of those wave systems allows their separation from the overall spectrum using the partition technique. Their further characterization is made using standard integrated parameters, which turn out much more meaningful when applied to the individual components than to the total spectrum. The parameters developed include the density distribution of spectral partitions, which is the main descriptor; the identified wave systems; the individual distribution of the characteristic frequencies, directions, wave height, wave age, seasonal variability of wind and waves; return periods derived from extreme value analysis; and crossing‐sea probabilities. This information is made available in web format for public use at http://www.modemat.epn.edu.ec/#/nereo. It is found that wave spectral statistics offers the possibility to synthesize data while providing a direct and comprehensive view of the local and regional wave conditions.
Large Eddy Simulation of Heat Entrainment Under Arctic Sea Ice
Authors: Ramudu Eshwan , Gelderloos Renske , Yang Di , Meneveau Charles , Gnanadesikan Anand 
Published: December 2017

AbstractArctic sea ice has declined rapidly in recent decades. The faster than projected retreat suggests that free‐running large‐scale climate models may not be accurately representing some key processes. The small‐scale turbulent entrainment of heat from the mixed layer could be one such process. To better understand this mechanism, we model the Arctic Ocean's Canada Basin, which is characterized by a perennial anomalously warm Pacific Summer Water (PSW) layer residing at the base of the mixed layer and a summertime Near‐Surface Temperature Maximum (NSTM) within the mixed layer trapping heat from solar radiation. We use large eddy simulation (LES) to investigate heat entrainment for different ice‐drift velocities and different initial temperature profiles. The value of LES is that the resolved turbulent fluxes are greater than the subgrid‐scale fluxes for most of our parameter space. The results show that the presence of the NSTM enhances heat entrainment from the mixed layer. Additionally there is no PSW heat entrained under the parameter space considered. We propose a scaling law for the ocean‐to‐ice heat flux which depends on the initial temperature anomaly in the NSTM layer and the ice‐drift velocity. A case study of “The Great Arctic Cyclone of 2012” gives a turbulent heat flux from the mixed layer that is approximately 70% of the total ocean‐to‐ice heat flux estimated from the PIOMAS model often used for short‐term predictions. Present results highlight the need for large‐scale climate models to account for the NSTM layer.
Effects of Model Resolution and Ocean Mixing on Forced Ice‐Ocean Physical and Biogeochemical Simulations Using Global and Regional System Models
Authors: Jin Meibing , Deal Clara , Maslowski Wieslaw , Matrai Patricia , Roberts Andrew , Osinski Robert , Lee Younjoo J. , Frants Marina , Elliott Scott , Jeffery Nicole , Hunke Elizabeth , Wang Shanlin 
Published: December 2017

AbstractThe current coarse‐resolution global Community Earth System Model (CESM) can reproduce major and large‐scale patterns but is still missing some key biogeochemical features in the Arctic Ocean, e.g., low surface nutrients in the Canada Basin. We incorporated the CESM Version 1 ocean biogeochemical code into the Regional Arctic System Model (RASM) and coupled it with a sea‐ice algal module to investigate model limitations. Four ice‐ocean hindcast cases are compared with various observations: two in a global 1° (40∼60 km in the Arctic) grid: G1deg and G1deg‐OLD with/without new sea‐ice processes incorporated; two on RASM's 1/12° (∼9 km) grid R9km and R9km‐NB with/without a subgrid scale brine rejection parameterization which improves ocean vertical mixing under sea ice. Higher‐resolution and new sea‐ice processes contributed to lower model errors in sea‐ice extent, ice thickness, and ice algae. In the Bering Sea shelf, only higher resolution contributed to lower model errors in salinity, nitrate (NO3), and chlorophyll‐a (Chl‐a). In the Arctic Basin, model errors in mixed layer depth (MLD) were reduced 36% by brine rejection parameterization, 20% by new sea‐ice processes, and 6% by higher resolution. The NO3 concentration biases were caused by both MLD bias and coarse resolution, because of excessive horizontal mixing of high NO3 from the Chukchi Sea into the Canada Basin in coarse resolution models. R9km showed improvements over G1deg on NO3, but not on Chl‐a, likely due to light limitation under snow and ice cover in the Arctic Basin.
Mechanisms of Mixed‐Layer Salinity Seasonal Variability in the Indian Ocean
Authors: Köhler Julia , Serra Nuno , Bryan Frank O. , Johnson Benjamin K. , Stammer Detlef 
Published: December 2017

AbstractBased on a joint analysis of an ensemble mean of satellite sea surface salinity retrievals and the output of a high‐resolution numerical ocean circulation simulation, physical processes are identified that control seasonal variations of mixed‐layer salinity (MLS) in the Indian Ocean, a basin where salinity changes dominate changes in density. In the northern and near‐equatorial Indian Ocean, annual salinity changes are mainly driven by respective changes of the horizontal advection. South of the equatorial region, between 45°E and 90°E, where evaporation minus precipitation has a strong seasonal cycle, surface freshwater fluxes control the seasonal MLS changes. The influence of entrainment on the salinity variance is enhanced in mid‐ocean upwelling regions but remains small. The model and observational results reveal that vertical diffusion plays a major role in precipitation and river runoff dominated regions balancing the surface freshwater flux. Vertical diffusion is important as well in regions where the advection of low salinity leads to strong gradients across the mixed‐layer base. There, vertical diffusion explains a large percentage of annual MLS variance. The simulation further reveals that (1) high‐frequency small‐scale eddy processes primarily determine the salinity tendency in coastal regions (in particular in the Bay of Bengal) and (2) shear horizontal advection, brought about by changes in the vertical structure of the mixed layer, acts against mean horizontal advection in the equatorial salinity frontal regions. Observing those latter features with the existing observational components remains a future challenge.
On the Climate Impacts of Upper Tropospheric and Lower Stratospheric Ozone
Authors: Xia Yan , Huang Yi , Hu Yongyun 
Published: December 2017

AbstractThe global warming simulations of the general circulation models (GCMs) are generally performed with different ozone prescriptions. We find that the differences in ozone distribution, especially in the upper tropospheric and lower stratospheric (UTLS) region, account for important model discrepancies shown in the ozone‐only historical experiment of the Coupled Model Intercomparison Project Phase 5 (CMIP5). These discrepancies include global high cloud fraction, stratospheric temperature, and stratospheric water vapor. Through a set of experiments conducted by an atmospheric GCM with contrasting UTLS ozone prescriptions, we verify that UTLS ozone not only directly radiatively heats the UTLS region and cools the upper parts of the stratosphere but also strongly influences the high clouds due to its impact on relative humidity and static stability in the UTLS region and the stratospheric water vapor due to its impact on the tropical tropopause temperature. These consequences strongly affect the global mean effective radiative forcing of ozone, as noted in previous studies. Our findings suggest that special attention should be paid to the UTLS ozone when evaluating the climate effects of ozone depletion in the 20th century and recovery in the 21st century. UTLS ozone difference may also be important for understanding the intermodel discrepancy in the climate projections of the CMIP6 GCMs in which either prescribed or interactive ozone is used.
Comment on “An Efficient and Stable Hydrodynamic Model With Novel Source Term Discretization Schemes for Overland Flow and Flood Simulations” by Xilin Xia et al.
Authors: Lu Xinhua , Mao Bing , Dong Bingjiang 
Published: December 2017

AbstractXia et al. (2017) proposed a novel, fully implicit method for the discretization of the bed friction terms for solving the shallow‐water equations. The friction terms contain h−7∕3 (h denotes water depth), which may be extremely large, introducing machine error when h approaches zero. To address this problem, Xia et al. (2017) introduces auxiliary variables (their equations (37) and (38)) so that h−4∕3 rather than h−7∕3 is calculated and solves a transformed equation (their equation (39)). The introduced auxiliary variables require extra storage. We implemented an analysis on the magnitude of the friction terms to find that these terms on the whole do not exceed the machine floating‐point number precision, and thus we proposed a simple‐to‐implement technique by splitting h−7∕3 into different parts of the friction terms to avoid introducing machine error. This technique does not need extra storage or to solve a transformed equation and thus is more efficient for simulations. We also showed that the surface reconstruction method proposed by Xia et al. (2017) may lead to predictions with spurious wiggles because the reconstructed Riemann states may misrepresent the water gravitational effect.
Effects of Heterogeneity, Connectivity, and Density Variations on Mixing and Chemical Reactions Under Temporally Fluctuating Flow Conditions and the Formation of Reaction Patterns
Authors: Pool Maria , Dentz Marco 
Published: December 2017

AbstractSolute mixing, spreading, and fast chemical reactions in aquifers are strongly influenced by spatial variability of the hydraulic properties, temporal flow fluctuations, and fluid density differences. We study the coupling of heterogeneity, transient forcing, and density‐driven flow on mixing and chemical reactions between two fluids of different density under a stable stratification. We consider the reaction of the fast dissolution of calcite. We find that temporal fluctuations and heterogeneity cause strong local enhancement of the mixing and reaction rates and this impact increases with the degree of connectivity of hydraulic conductivity. The global mixing and reactivity, however, are on the order of or smaller than their homogeneous counterparts due to heterogeneity‐induced fluid segregation. The local maxima of the mixing and reaction rates are found to be located around strongly stretched regions corresponding to high velocity zones where dispersive mass transfer mechanisms are increased by dispersion. We also find that density variations compress the interface, which in turn emphasizes local maxima in mixing and reaction rates. Numerical results provide evidence that the stretching of the interface induced by spatial heterogeneity and transient effects coupled with density variations lead to the formation of complex patterns of reactive hotspots, zones of enhanced reaction efficiency, and that its distribution is directly linked to the deformation properties and topology of the flow field. These results provide new insights into the role of spatial and temporal variability on the mixing and reaction efficiency as well as the formation of reactive geochemical patterns in actual environmental systems.
High‐Performance, Self‐Driven Photodetector Based on Graphene Sandwiched GaSe/WS2 Heterojunction
Authors: Lv Quanshan , Yan Faguang , Wei Xia , Wang Kaiyou 
Published: December 2017

AbstractRestacking the exfoliated 2D layered materials into complex heterostructures with new functionality has opened a new platform for materials engineering and device application. In this work, graphene sandwiched p‐GaSe/n‐WS2 vertical heterostructures are fabricated for photodetection. The devices show excellent performance on photodetection from ultraviolet to visible wavelength range, including high photoresponsivity (≈149 A W−1 at 410 nm), short response time of 37 µs, and self‐powered photodetection. The scanning photocurrent microscopy is also employed to investigate the photocurrent generation in the heterojunction and a significant enhancement of the photoresponse is found in the overlapping region. The results suggest that the graphene sandwiched vertical heterojunctions are promising in future novel optoelectronic devices applications.
Synthesis of polycarboxylate superplasticizers using an acrylic acid‐rich wastewater from acrolein production
Authors: Pei Jikai , Wang Ziwei , Ren Jianguo , Liu Diansheng 
Published: December 2017

AbstractIn this paper, an acrylic acid‐rich wastewater from the production of propylene to acrolein was used to synthesize the polycarboxylate superplasticizers. First, the acrylic acid‐rich wastewater was oxidized. Then, two kinds of unsaturated polyether macromonomers {methallyl polyethylene glycol (HPEG) and isoprenol polyethylene glycol (IPEG)} and the oxidized wastewater were copolymerized with it, respectively, by free radical polymerization in aqueous solution. The monomer conversion, molecular weight, molecular weight distribution of the copolymers of gel permeation chromatography (GPC) were characterized. The performance of the two copolymers was characterized by measuring paste flow, adsorption using GPC method, and the applied behavior of premixed concrete. The results showed that the synthesized copolymers could meet the requirement of application in contrast to the commodity product.
Height–income association in developing countries: Evidence from 14 countries
Authors: Patel Pankaj C. , Devaraj Srikant 
Published: December 2017

AbstractObjectivesThe purpose of this study was to assess whether the height–income association is positive in developing countries, and whether income differences between shorter and taller individuals in developing countries are explained by differences in endowment (ie, taller individuals have a higher income than shorter individuals because of characteristics such as better social skills) or due to discrimination (ie, shorter individuals have a lower income despite having comparable characteristics).MethodsInstrumental variable regression, Oaxaca–Blinder decomposition, quantile regression, and quantile decomposition analyses were applied to a sample of 45 108 respondents from 14 developing countries represented in the Research on Early Life and Aging Trends and Effects (RELATE) study.ResultsFor a one‐centimeter increase in country‐ and sex‐adjusted median height, real income adjusted for purchasing power parity increased by 1.37%. The income differential between shorter and taller individuals was explained by discrimination and not by differences in endowments; however, the effect of discrimination decreased at higher values of country‐ and sex‐adjusted height.ConclusionsTaller individuals in developing countries may realize higher income despite having characteristics similar to those of shorter individuals.
Vasodilator dysfunction and oligodendrocyte dysmaturation in aging white matter
Authors: Bagi Zsolt , Brandner Dieter D. , Le Phuong , McNeal David W. , Gong Xi , Dou Huijuan , Fulton David J. , Beller Allison , Ngyuen Thuan , Larson Eric B. , Montine Thomas J. , Keene C. Dirk , Back Stephen A. 
Published: December 2017

ObjectiveMicrovascular brain injury (mVBI) is a common pathological correlate of vascular contributions to cognitive impairment and dementia (VCID) that leads to white matter (WM) injury (WMI). VCID appears to arise from chronic recurrent white matter ischemia that triggers oxidative stress and an increase in total oligodendrocyte lineage cells. We hypothesized that mVBI involves vasodilator dysfunction of white matter penetrating arterioles and aberrant oligodendrocyte progenitor cell (OPC) responses to WMI.MethodsWe analyzed cases of mVBI with low Alzheimer's disease neuropathological change in prefrontal cortex WM from rapid autopsies in a population‐based cohort where VCID frequently occurs. Arteriolar vasodilator function was quantified by videomicroscopy. OPC maturation was quantified using lineage specific markers.ResultsAcetylcholine‐mediated arteriolar dilation in mVBI was significantly reduced in WM penetrators relative to pial arterioles. Astrogliosis‐defined WMI was positively associated with increased OPCs and was negatively associated with decreased mature oligodendrocytes.InterpretationSelectively impaired vasodilator function of WM penetrating arterioles in mVBI occurs in association with aberrant differentiation of OPCs in WMI, which supports that myelination disturbances in VCID are related to disrupted maturation of myelinating oligodendrocytes. Ann Neurol 2018;83:142–152
Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity, Stability, and Temperature‐ Dependent Activation Properties
Authors: Yoshida Takuya , Murayama Toru , Sakaguchi Norihito , Okumura Mitsutaka , Ishida Tamao , Haruta Masatake 
Published: December 2017

AbstractNanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs4[α‐SiW12O40]⋅n H2O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was −67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Auδ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions.
Design of the First‐in‐Class, Highly Potent Irreversible Inhibitor Targeting the Menin‐MLL Protein–Protein Interaction
Authors: Xu Shilin , Aguilar Angelo , Xu Tianfeng , Zheng Ke , Huang Liyue , Stuckey Jeanne , Chinnaswamy Krishnapriya , Bernard Denzil , Fernández‐Salas Ester , Liu Liu , Wang Mi , McEachern Donna , Przybranowski Sally , Foster Caroline , Wang Shaomeng 
Published: December 2017

AbstractThe structure‐based design of M‐525 as the first‐in‐class, highly potent, irreversible small‐molecule inhibitor of the menin‐MLL interaction is presented. M‐525 targets cellular menin protein at sub‐nanomolar concentrations and achieves low nanomolar potencies in cell growth inhibition and in the suppression of MLL‐regulated gene expression in MLL leukemia cells. M‐525 demonstrates high cellular specificity over non‐MLL leukemia cells and is more than 30 times more potent than its corresponding reversible inhibitors. Mass spectrometric analysis and co‐crystal structure of M‐525 in complex with menin firmly establish its mode of action. A single administration of M‐525 effectively suppresses MLL‐regulated gene expression in tumor tissue. An efficient procedure was developed to synthesize M‐525. This study demonstrates that irreversible inhibition of menin may be a promising therapeutic strategy for MLL leukemia.
Investigations on matrix network characteristics in NBR/silica nanocomposites: Resolving matrix bulk density and network molecular weight and their alterations due to filler‐curing agent interactions
Authors: Khabiri Mohammad , Jafari Seyed Hassan , Pourhossaini Mohammad Reza , Khonakdar Hossein Ali 
Published: December 2017

ABSTRACTPresence of filler in an elastomeric composite can affect curing characteristics due to possible interaction with curing agents. Alteration of the curing characteristics can change intrinsic properties of elastomer including its bulk density and swelling behavior. In this study, a series of acrylonitrile butadiene rubber (NBR) with various curing levels was prepared. From the experimental data the bulk density and network molecular weight (Mc,sw) were specified and a relationship was established between these parameters. In order to determine the swelling characteristics of NBR in presence of filler, another series of NBR/silica nanocomposites was prepared with various nanosilica loadings under a constant content of curing agents and curing conditions. With the use of the swelling data and applying the obtained relationship, the Mc,sw and bulk density of the filled NBR matrix were resolved. The Mc,sw values obtained by considering the influence of nanosilica on curing characteristics of NBR were compared with those obtained simply based on bulk density of raw rubber. This comparison confirmed that there are considerable differences between these values. With increasing nanosilica contents, and hence, increasing the negative impact of the filler on reducing curing degree of NBR, the bulk density of filled NBR matrix was decreased. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46170.
UV and corrosion protective behavior of polymer hybrid coating on mild steel
Authors: Pugazhenthi I. , Mohammed Safiullah S. , Anver Basha K. 
Published: December 2017

ABSTRACTPoly[(pyridine‐4‐yl‐methyl)methacrylate‐co‐butyl methacrylate] [poly(PyMMA‐co‐BMA)] and its ZnO nanocomposites [poly(PyMMA‐co‐BMA)/ZnO] were coated on the mild steel substrate (MS) to improve the corrosion resistance by blocking the destructive ultraviolet radiation (UV‐radiation) and corrosive ions as well. The optical and anticorrosive properties of poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (1.0, 1.5, and 2.5 wt %) coatings were evaluated. The surface characterization techniques like UV visible spectroscopy and scanning electron microscope were taken to confirm the formation of poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (2.5 wt %) coating on MS. The optical studies revealed that the poly(PyMMA‐co‐BMA)/ZnO (2.5 wt %) coating displays excellent UV blocking properties than other nanocomposite coatings (1.0 and 1.5 wt %). The potentiodynamic polarization and electrochemical impedance spectroscopy studies show that the poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (1.0, 1.5, and 2.5 wt %) coated MS in 3.5% (w/v) NaCl provides better protection against corrosion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46175.