bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variability of Arctic sea‐ice topography and its impact on the atmospheric surface drag
Authors: Castellani G. , Lüpkes C. , Hendricks S. , Gerdes R. 
Published: September 2014

AbstractOver the polar oceans, near‐surface atmospheric transport of momentum is strongly influenced by sea‐ice surface topography. The latter is analyzed on the basis of laser altimeter data obtained during airborne campaigns between 1995 and 2011 over more than 10,000 km of flight distance in different regions of the Arctic Ocean. Spectra of height and spacing between topographic features averaged over 10 km flight sections show that typical values are 0.45 m for the mean height and about 20 m for the mean spacing. Nevertheless, the variability is high and the spatial variability is stronger than the temporal one. The total topography spectrum is divided into a range with small obstacles (between 0.2 m and 0.8 m height) and large obstacles (≥0.8 m). Results show that large pressure ridges represent the dominant topographic feature only along the coast of Greenland. In the Central Arctic, the concentration of large ridges decreased over the years, accompanied by an increase of small obstacles concentration and this might be related to decreasing multiyear ice. The application of a topography‐dependent parameterization of neutral atmospheric drag coefficients reflects the large variability in the sea‐ice topography and reveals characteristic differences between the regions. Based on the analysis of the two spectral ranges, we find that the consideration of only large pressure ridges is not enough to characterize the roughness degree of an ice field, and the values of drag coefficients are in most regions strongly influenced by small obstacles.
A multiyear, global gridded fossil fuel CO2 emission data product: Evaluation and analysis of results
Authors: Asefi‐Najafabady S. , Rayner P. J. , Gurney K. R. , McRobert A. , Song Y. , Coltin K. , Huang J. , Elvidge C. , Baugh K. 
Published: September 2014

AbstractHigh‐resolution, global quantification of fossil fuel CO2 emissions is emerging as a critical need in carbon cycle science and climate policy. We build upon a previously developed fossil fuel data assimilation system (FFDAS) for estimating global high‐resolution fossil fuel CO2 emissions. We have improved the underlying observationally based data sources, expanded the approach through treatment of separate emitting sectors including a new pointwise database of global power plants, and extended the results to cover a 1997 to 2010 time series at a spatial resolution of 0.1°. Long‐term trend analysis of the resulting global emissions shows subnational spatial structure in large active economies such as the United States, China, and India. These three countries, in particular, show different long‐term trends and exploration of the trends in nighttime lights, and population reveal a decoupling of population and emissions at the subnational level. Analysis of shorter‐term variations reveals the impact of the 2008–2009 global financial crisis with widespread negative emission anomalies across the U.S. and Europe. We have used a center of mass (CM) calculation as a compact metric to express the time evolution of spatial patterns in fossil fuel CO2 emissions. The global emission CM has moved toward the east and somewhat south between 1997 and 2010, driven by the increase in emissions in China and South Asia over this time period. Analysis at the level of individual countries reveals per capita CO2 emission migration in both Russia and India. The per capita emission CM holds potential as a way to succinctly analyze subnational shifts in carbon intensity over time. Uncertainties are generally lower than the previous version of FFDAS due mainly to an improved nightlight data set.
First “in situ” determination of gas transport coefficients (, , and ) from bulk gas concentration measurements (O2, N2, Ar) in natural sea ice
Authors: Crabeck Odile , Delille B. , Rysgaard S. , Thomas D. N. , Geilfus N.‐X. , Else B. , Tison J.‐L. 
Published: September 2014

AbstractWe report bulk gas concentrations of O2, N2, and Ar, as well as their transport coefficients, in natural landfast subarctic sea ice in southwest Greenland. The observed bulk ice gas composition was 27.5% O2, 71.4% N2, and 1.09% Ar. Most previous studies suggest that convective transport is the main driver of gas displacement in sea ice and have neglected diffusion processes. According to our data, brines were stratified within the ice, so that no convective transport could occur within the brine system. Therefore, diffusive transport was the main driver of gas migration. By analyzing the temporal evolution of an internal gas peak within the ice, we deduced the bulk gas transport coefficients for oxygen (DO2), argon (DAr), and nitrogen (DN2). The values fit to the few existing estimates from experimental work, and are close to the diffusivity values in water (10−5 cm2 s−1). We suggest that gas bubbles escaping from the brine to the atmosphere—as the ice gets more permeable during melt—could be responsible for the previously reported high transport coefficients. These results underline that when there is no convective transport within the sea ice, the transport of gas by diffusion through the brines, either in the liquid or gaseous phases, is a major factor in controlling the ocean‐atmosphere exchange.
Introduction of groundwater capillary rises using subgrid spatial variability of topography into the ISBA land surface model
Authors: Vergnes J.‐P. , Decharme B. , Habets F. 
Published: September 2014

AbstractThis paper presents a simple method for representing upward capillary fluxes from shallow groundwater into the unsaturated soil column of the large‐scale hydrological models generally used at low resolution in global climate models. The groundwater scheme implemented in the Total Runoff Integrating Pathways river‐routing model in a previous study is coupled with the Interaction between Soil Biosphere Atmosphere (ISBA) land surface model. In this coupling, the simulated water table depth acts as the lower boundary condition for the soil moisture diffusive equation. An original parameterization accounting for the subgrid topography inside each grid cell is proposed in order to compute this fully coupled soil lower boundary condition. The impact of this coupling on the simulated water budget is evaluated over France for the 1989–2009 period. Simulations are performed at high (1/12°) and low (0.5°) resolutions. Upward capillary fluxes induce a decrease in the simulated recharge from ISBA to the aquifers and contributes to an enhancement of the soil moisture memory. The simulated water table depths are then lowered, which induces a slight decrease in the simulated mean annual river discharges. These differences do not affect the comparison with observations. As a consequence, the simulated river discharges and water table heads compare still well with observations for the two soil bottom condition (free drain or fully coupled). It confirms the suitability of the coupling parameterization using subgrid spatial variability of topography. Compared to a free drain experiment, upward capillary fluxes at the bottom of the soil increase the mean annual evapotranspiration simulated over the aquifer domain by 3.12% and 1.54% at high and low resolutions, respectively. This increase can locally reach 50% and 30%, respectively.
Lossen Rearrangements under Heck Reaction Conditions
Authors: AbdelHafez El‐Shimaa M. N. , Aly Omar M. , Abuo‐Rahma Gamal El‐Din A. A. , King S. Bruce 
Published: September 2014

AbstractThe classical Lossen rearrangement converts activated hydroxamic acids to isocyanates that form numerous products upon their reaction with nucleophiles. We report a simple and highly efficient method of using Heck reaction conditions to initiate Lossen rearrangements of hydroxamic acids. In addition, Lossen rearrangements occur in the presence of palladium(II) acetate or triethylamine, components of the Heck reaction, alone. A potential mechanism is provided to explain this reactivity and these results show that Heck reactions and Lossen rearrangements occur under the same conditions and may provide new methods for facile initiation of Lossen rearrangements.magnified image
Synthesis of 5‐(Fluoromethyl)‐4,5‐dihydroisoxazoles by Silver‐ Catalyzed Oxyfluorination of Unactivated Alkenes
Authors: Liu Yan‐Yun , Yang Ji , Song Ren‐Jie , Li Jin‐Heng 
Published: September 2014

AbstractA new silver‐catalyzed oxyfluorination of unactivated alkenes using commercially available Selectfluor as the fluorine source is presented. This method provides a new access to 5‐(fluoromethyl)‐4,5‐dihydroisoxazoles, and represents a new example of alkene 1,2‐difunctionalization by simultaneously forming two new carbon‐heteroatom bonds.magnified image
Iodine‐Promoted Sequential C(sp3)H Functionalization Reactions: An Annulation Strategy for the Construction of 3‐Methylthio‐4‐arylmaleimides
Authors: Gao Qinghe , Wu Xia , Li Yuhong , Liu Shan , Meng Xianggao , Wu Anxin 
Published: September 2014

AbstractA new process has been developed for the iodine‐promoted sequential C(sp3)H bond functionalization of methyl ketones and acetamides. This reaction represents a novel annulation strategy for the synthesis of 3‐(methylthio)‐4‐aryl‐1H‐pyrrole‐2,5‐diones, and involves an α‐ketoimide as the key intermediate. Furthermore, DMSO was converted to DMS in situ, which served as the methylthiolation reagent in the reaction. This protocol constitutes an efficient and convenient method for the methylthiolation of substrates bearing a wide range of functional groups.magnified image
Amyloid‐β efflux from the central nervous system into the plasma
Authors: Roberts Kaleigh Filisa , Elbert Donald L. , Kasten Tom P. , Patterson Bruce W. , Sigurdson Wendy C. , Connors Rose E. , Ovod Vitaliy , Munsell Ling Y. , Mawuenyega Kwasi G. , Miller‐Thomas Michelle M. , Moran Christopher J. , Cross Dewitte T. , Derdeyn Colin P. , Bateman Randall J. 
Published: September 2014

ObjectiveThe aim of this study was to measure the flux of amyloid‐β (Aβ) across the human cerebral capillary bed to determine whether transport into the blood is a significant mechanism of clearance for Aβ produced in the central nervous system (CNS).MethodsTime‐matched blood samples were simultaneously collected from a cerebral vein (including the sigmoid sinus, inferior petrosal sinus, and the internal jugular vein), femoral vein, and radial artery of patients undergoing inferior petrosal sinus sampling. For each plasma sample, Aβ concentration was assessed by 3 assays, and the venous to arterial Aβ concentration ratios were determined.ResultsAβ concentration was increased by ∼7.5% in venous blood leaving the CNS capillary bed compared to arterial blood, indicating efflux from the CNS into the peripheral blood (p < 0.0001). There was no difference in peripheral venous Aβ concentration compared to arterial blood concentration.InterpretationOur results are consistent with clearance of CNS‐derived Aβ into the venous blood supply with no increase from a peripheral capillary bed. Modeling these results suggests that direct transport of Aβ across the blood–brain barrier accounts for ∼25% of Aβ clearance, and reabsorption of cerebrospinal fluid Aβ accounts for ∼25% of the total CNS Aβ clearance in humans. Ann Neurol 2014;76:837–844
Preparation and dielectric properties of (Ba0.5Sr0.4Ca0.1)TiO3/polystyrene composites
Authors: Zhang Liang , Zhao Jun , Huang Er‐Quan , Zha Jun‐Wei , Dang Zhi‐Min 
Published: September 2014

ABSTRACTPolymer composites with polystyrene (PS) as matrix and (Ba0.5Sr0.4Ca0.1)TiO3 (BSCT) as fillers are prepared by solution casting method. It is found that the dielectric constant of the prepared BSCT/PS composites increases with increasing filler content over the frequency range from 100 Hz to 500 MHz. And the dielectric properties of the composites show a good temperature independency over the range of −30°C to 80°C. For the composite with 50 vol % filler content, the dielectric constant and dielectric loss are comparable with the literature values reported for other PS composites used for microwave substrate. Several theoretical models are used to compare with the experimental data of the dielectric constant of the composites. The microstructure and thermal properties of the composites were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41398.
Operating window of solution casting. II. Non‐Newtonian fluids
Authors: Huang Yuan‐Chang , Wang Tai‐Zan , Liu Ta‐Jo , Tiu Carlos 
Published: September 2014

ABSTRACTThe operating windows of the solution casting of two polymeric liquids were evaluated experimentally. The experimental setup and procedure were the same as used previously for the casting of Newtonian fluids (Journal of Applied Polymer Science 2013, 129, 507–516). Aqueous carboxymethylcellulose/glycerol solutions exhibited pure shear‐thinning behavior at low polymer concentrations but became viscoelastic at high polymer concentrations, whereas polyacrylamide/glycerol solutions showed viscoelastic behavior over a wide range of concentrations. The shear‐thinning behavior, in conjunction with a low level of elasticity, of the casting solution was found to be useful in expanding the stable operating windows. However, an opposite effect on the operating windows was found for highly elastic solutions. The non‐Newtonian effect on the maximum stable casting speed was prominent only when the capillary number exceeded unity. Defects outside of the operating window were mostly similar to those observed in Newtonian solution casting. For highly concentrated solutions, a new rough surface defect was observed. This defect could be attributed to polymer chain entanglement, alignment, or breakup. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41411.
Morphology, structure, and properties of poly(lactic acid) microporous films containing poly(butylene terephthalate) fine fibers fabricated by biaxial stretching
Authors: Samthong Chavakorn , Seemork Jiraporn , Nobukawa Shogo , Yamaguchi Masayuki , Praserthdam Piyasan , Somwangthanaroj Anongnat 
Published: September 2014

ABSTRACTThe effects of size and shape, i.e., sphere and fiber, of dispersed poly(butylene terephthalate) (PBT) in poly(lactic acid) (PLA) matrix on the morphology and porous structure of the biaxially stretched films are comparatively investigated. Scanning electron microscope results confirm that the PBT fine fibers can be produced by melt‐stretching following by fast quenching. Rheological characterization reveals the random network structure of PBT fibers. Further, the stretched films composed of spherical PBT particles show the ellipsoidal microvoids due to the interfacial debonding, and the void size relates to the particle size of PBT. However, size of PBT droplets does not influence the void content of the stretched films. The void content considerably increases for equibiaxial deformation as compared with planar deformation, particularly at high draw ratio. Additionally, the stretched films containing fibrous dispersion exhibit the nonaffine behavior and the highest void content of 8%, which is probably due to the localized deformation between fibers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41415.
Production of polyols and waterborne polyurethane dispersions from biodiesel‐derived crude glycerol
Authors: Hu Shengjun , Luo Xiaolan , Li Yebo 
Published: September 2014

ABSTRACTThis study investigated the preparation of polyols and waterborne polyurethane dispersions (CG‐WPUDs) from biodiesel‐derived crude glycerol. The polyols were produced from biodiesel‐derived crude glycerol via a thermochemical conversion process, which converted crude glycerol components such as glycerol, free fatty acids, and methyl esters of fatty acids (FAMEs) into polyols under optimized reaction conditions. CG‐WPUDs with different hard segments (41.0% to 63.2 wt %) were prepared from the crude glycerol‐based polyols produced. PU coating films cast from CG‐WPUDs showed increasing glass transition temperatures (Tg) from 63°C to 81°C when hard segment content increased from 41.0% to 63.2% and had good thermal stability up to 240°C. CG‐WPUD‐based coatings showed excellent adhesion to steel panel surfaces, pencil hardness as high as F, but relatively low flexibility. This study demonstrated the potential of biodiesel‐derived crude glycerol for the production of bio‐based polyols and WPUDs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41425.
Membrane adsorbers comprising grafted glycopolymers for targeted lectin binding
Authors: Chenette Heather C. S. , Husson Scott M. 
Published: September 2014

ABSTRACTThis work details the design and testing of affinity membrane adsorbers for lectin purifications that incorporate glucose‐containing glycopolymers. It is the selective interaction between the sugar residues of the glycopolymer and the complementary carbohydrate‐binding domain of the lectin that provides the basis for the isolation and purification of lectins from complex biological media. The design approach used in these studies was to graft glycopolymer ‘tentacles’ from macroporous regenerated cellulose membranes by atom transfer radical polymerization. As shown in earlier studies, this design approach can be used to prepare high‐productivity membrane adsorbers. The model lectin, concanavalin A (conA), was used to evaluate membrane performance in bind‐and‐elute purification, using a low‐molecular‐weight sugar for elution. The membrane capacity for binding conA was measured at equilibrium and under dynamic conditions using flow rates of 0.1 and 1.0 mL/min. The first Damkohler number was estimated to relate the adsorption rate to the convective mass transport rate through the membrane bed. It was used to assess whether adsorption kinetics or mass transport contributed the primary limitation to conA binding. Analyses indicate that this system is not limited by the accessibility of the binding sites, but by the inherent rate of adsorption of conA onto the glycopolymer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41437.
Preparation, morphology, and conductivity of waterborne, nanostructured, cationic polyurethane/polypyrrole conductive coatings
Authors: Wang Haihua , Liu Yun , Fei Guiqiang , Lan Jing 
Published: September 2014

ABSTRACTTo endow cellulose fiber papers with good conductivity and simultaneously retain the mechanical strength of the conductive paper, a kind of waterborne, nanostructured, cationic polyurethane (CPU)/polypyrrole (PPy) conductive coatings were developed to modify the paper surface. Fourier transform infrared spectroscopy, atomic force microscopy, and thermogravimetry–differential thermogravimetry demonstrated that the peak associated with hydrogen bonding between NH and CO of CPU was shifted, and chemical bonds between CPU and PPy were formed. Good compatibility between CPU and PPy was simultaneously established. Transmission electron microscopy and atomic force microscopy also suggested that PPy was encased and embedded in the CPU colloidal particles in a uniform style, and the surface of the CPU/PPy film was covered with a smooth, coherent conductive layer. With increasing pyrrole (Py) content from 5 to 20 wt %, the particle size increased from 55.08 to 74.59 nm, and the dispersity index (DPI) decreased. In addition, the conductivity of CPU/PPy increased from 0.1 to 5.0 S/cm. When the Py content was greater than 20 wt %, apparent increases in the particle size and DPI were detected as was particle coagulation; this resulted in decreased conductivity. Compared with the uncoated paper, the paper coated with CPU/PPy dispersions displayed different surface morphologies. The surface of the paper was completely enwrapped by the CPU/PPy conductive films when the coating amount was 45.42 g/m2. With increasing coating amounts from 10.35 to 67.86 g/m2, the conductivity of the conductive coated paper increased from 2.78 × 10−3 to 2.16 S/cm, the tensile strength increased from 35.3 to 60.4 N m/g, and the conductive coated paper displayed good conductivity stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41445.
Kalman Filtering Over Lossy Networks Under Switching Sensors
Authors: You Keyou , Sui Tianju , Fu Minyue 
Published: September 2014

AbstractIn this paper, we study the mean square stability of Kalman filtering of a discrete‐time stochastic system under two periodically switching sensors. The sensor measurements are sent to a remote estimator over a lossy channel whose packet loss process is independent and identically distributed. We prove that the problem can be converted into the stability analysis of Kalman filtering using two sensors at each time, and the measurements of each sensor are transmitted to the estimator via an independent lossy channel of the same packet loss rate. Some necessary and/or sufficient conditions for stability of the estimation error covariance matrices are derived. Moreover, the effect of the sensor switching on the filter stability is revealed. Their implications and relationships with related results in the literature are discussed.
Synchronization Criterion and Control Scheme for Lur'e Type Complex Dynamical Networks with Switching Topology and Coupling Time‐Varying Delay
Authors: Zhang Youjian , Li Peiran , Yang Qiang , Yan Wenjun 
Published: September 2014

AbstractIn this paper, the synchronization problem is addressed in the context of Lur'e type complex switched network (CSN) with coupling time‐varying delay in which every node is a Lur'e system. Based on the Lyapunov–Krasovskii theory and linear matrix inequality (LMI) technique, a delay‐dependent synchronization criterion and a decentralized state feedback dynamic controller for synchronization of CSNs have been proposed. By choosing a common Lyapunov–Krasovskii functional and using the combined reciprocal convex technique, some previously ignored terms can be reconsidered and less conservative conditions can be obtained. In addition, by using an eigenvalue‐decoupling method and convex optimization theory, high‐dimension LMIs are decoupled into a set of low‐dimension ones and the computation complexity of the criterion can be significantly reduced. The effectiveness and applicability of the suggested control solution is verified and assessed through the analysis for two numerical examples.