bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large winds and wind shears caused by the nonlinear interactions between gravity waves and tidal backgrounds in the mesosphere and lower thermosphere
Authors: Liu Xiao , Xu Jiyao , Yue Jia , Liu Han Li , Yuan Wei 
Published: August 2014

AbstractA two‐dimensional nonlinear numerical model was used to simulate large winds (≥ 100 m s−1) and wind shears (≥ 40 m s−1 km−1) in the mesosphere and lower thermosphere (MLT) that are caused by the interaction between gravity waves (GWs) and migrating tidal background. By varying the wavelengths of GWs and the phases of diurnal and semidiurnal tides, 64 numerical experiments were performed. Our numerical experiments indicate that both migrating diurnal and semidiurnal tides strongly modulate the occurrence of GW breaking, and the resulted large winds and wind shears. The simulated large winds and wind shears are in good agreement with those from the rocket‐sounding chemical release measurements. Moreover, the occurrence of large wind shears highly depends on the phases of migrating tides in local time, which is in agreement with the reported lidar observations. The local time dependence of large wind shears is mainly attributed to the filtering and/or hindering effects of diurnal and semidiurnal tidal winds on GWs. Our simulation reveals that the nonlinear interactions between GWs breaking and the migrating diurnal and semidiurnal tides may play an important role in driving the large winds and wind shears in the MLT region and their local time dependence.
Reaction‐driven fracturing of porous rock
Authors: Ulven O. I. , Jamtveit B. , Malthe‐Sørenssen A. 
Published: August 2014

AbstractA 2‐D computer model has been developed to investigate fluid‐mediated transformation processes such as chemical weathering, mineral carbonation, and serpentinization that require transport of H2O and/or CO2 into reacting rock volumes. Hydration and carbonation cause local volume expansion, and the resulting nonuniform stresses may drive fracturing, which increases both the rate of transport and the accessible reactive surface area in the system and thus accelerates the rate of the transformation process. The model couples reactions, fracturing, and fluid transport for systems with a range of initial porosities, assumed constant throughout the process. With low initial porosity, a sharp reaction front between completely reacted material and unreacted material propagates into unaltered rock, while for high porosities, diffuse reaction fronts are formed in which a large fraction of the initial volume is partly reacted. When diffusive transport is rate limiting, the total reaction rate depends on porosity to a power N, where N is in the range 0.45–2. The exponent N increases as the reaction‐generated expansion decreases. In high‐porosity rocks, the total reaction rate is limited by reaction kinetics, and it is thus insensitive to porosity variations. As the volume increasing reaction proceeds, fracturing divides the unreacted porous material into subdomains, which may undergo further subdivision as they are consumed by the reaction. The total reaction rate and progress depend on the initial geometry of a reacting domain, and this significantly affects the weathering profiles for systems that evolve from an initial assembly of blocks with different sizes and shapes.
Failure mechanisms in coal: Dependence on strain rate and microstructure
Authors: Zhao Yixin , Liu Shimin , Zhao Gao‐Feng , Elsworth Derek , Jiang Yaodong , Han Jingli 
Published: August 2014

AbstractThe brittle coal failure behavior under various axial strain rates from 10−3 to 10−2 s−1 is experimentally and numerically studied. The numerical microscale finite difference model is built on the accurate X‐ray microcomputed tomography images, which provides a ground‐breaking and bottom‐up approach to investigate the effects of microstructure on coal failure under various strain rates. Experimentally, prior to loading, the coal sample is scanned, and the three‐dimensional coal structure model is constructed. The microheterogeneous structures are incorporated in the model, which facilitates the deformation and failure mechanism analysis under different loading conditions. The results reveal that the microheterogeneous structures significantly affect the evolution of stress concentrations and deformation behaviors in the sample. The coal tends to fail in the shear mode before the peak strength, since the shear zone is created with high displacements. However, tensile failure ultimately controls the failure process after the peak strength. Notably, the strain rate dependence of coal strength is observed, and an empirical relationship is proposed to describe the dynamic strength of the coal under various loading strain rates. Importantly, the coal strengthens with an increase in strain rate. For brittle material, such as coal, the strength and failure mechanism are strain rate and microstructure dependent. The strain rate‐dependent coal strength index (n) is found to be a dynamic parameter in the range of strain rate from 10−3 to 10−2 s−1, and this finding may extend the concept of strain rate dependence over a broader range of loading conditions.
Assessing a dry surface layer‐based soil resistance parameterization for the Community Land Model using GRACE and FLUXNET‐MTE data
Authors: Swenson S. C. , Lawrence D. M. 
Published: August 2014

AbstractThe Community Land Model (CLM) exhibits biases in evapotranspiration (ET) and total water storage (TWS) in semiarid regions. The TWS seasonal cycle amplitude is too low, while evapotranspiration is too strong and variable. These biases are consistent with excessive soil evaporation when the canopy is sparse or absent, which reduces moisture inputs into the ground. Here we improve the simulation of soil evaporation by replacing CLM's existing empirical soil resistance parameterization with a more mechanistically based formulation in which soil evaporation is controlled by the rate of diffusion of water vapor through a dry surface layer (DSL). The thickness of the DSL is parameterized as a soil‐type dependent function of top layer soil moisture. Soil resistances are calculated from the DSL thickness combined with a soil tortuosity factor. Compared to the existing CLM soil resistance parameterization, the DSL‐based soil resistances for a given soil moisture value are generally larger, especially for moister soils. CLM simulations using the DSL‐based soil resistance expression have reduced biases of ET relative to the FLUXNET‐MTE (Model Tree Ensemble) data set and TWS relative to Gravity Recovery and Climate Experiment (GRACE) observations. Averaged over global semiarid regions, the CLM mean annual amplitude of TWS increases from 26.3 mm to 32.5 mm when the new soil resistance parameterization is used, in good agreement with the GRACE mean annual amplitude for these regions of 32.2 ±2.1 mm. CLM mean annual ET, averaged over global semiarid regions, decreases from 27.8 mm/month to 23.5 mm/month, closer to the FLUXNET‐MTE mean annual ET of 21.1 ± 0.9 mm/month. The seasonal amplitude of CLM ET also decreases, from 23.3 mm/month to 18.3 mm/month compared to 14.9 ± 1.1 mm/month for FLUXNET‐MTE.
Interaction among alluvial cover, bed roughness, and incision rate in purely bedrock and alluvial‐bedrock channel
Authors: Inoue Takuya , Izumi Norihiro , Shimizu Yasuyuki , Parker Gary 
Published: August 2014

AbstractA major control on bedrock incision is the interaction between alluvial cover and erosive mobile grains. The extent of alluvial cover is typically predicted as a function of relative sediment flux (sediment supply rate over bed load transport capacity, qbs/qbc), yet little is known about how the bed roughness affects the alluvial cover. We performed field experiments with various flow discharges, sediment supply rates, grain sizes, and bed surface topographies. We then developed physically based models for estimating the threshold of sediment movement and the extent of alluvial cover, so as to include the effect of roughness change. The results for the threshold of sediment movement and the extent of alluvial cover obtained from our models show reasonable agreement with the results of the field experiments. We explored the sensitivity of the models to variations in sediment supply and bedrock relative roughness (bedrock hydraulic roughness height over grain size, ksb/d). The results suggest the following: (1) a larger relative roughness yields a greater dimensionless critical shear stress required for initial sediment motion; (2) at a given sediment supply rate, the extent of alluvial cover is larger when the relative roughness is larger; (3) when the sediment supply rate and the relative roughness are small, throughput bed load moves over (and can abrade) a purely bedrock channel with no alluvial cover; and (4) the critical value of sediment supply rate below which throughput bed load transport occurs increases with decreasing relative roughness. The experimental results and analysis provide a framework for treating the (a) incisional morphodynamics of purely bedrock rivers by throughput bed load with no alluvial cover, (b) incisional/alluvial morphodynamics of mixed bedrock‐alluvial rivers, and (c) purely alluvial morphodynamics, as well as the transition between these states.
Evaluation of slope stability with respect to snowpack spatial variability
Authors: Gaume J. , Schweizer J. , van Herwijnen A. , Chambon G. , Reuter B. , Eckert N. , Naaim M. 
Published: August 2014

AbstractThe evaluation of avalanche release conditions constitutes a great challenge for risk assessment in mountainous areas. The spatial variability of snowpack properties has an important impact on snow slope stability and thus on avalanche formation, since it strongly influences failure initiation and crack propagation in weak snow layers. Hence, the determination of the link between these spatial variations and slope stability is very important, in particular, for avalanche public forecasting. In this study, a statistical‐mechanical model of the slab‐weak layer (WL) system relying on stochastic finite element simulations is used to investigate snowpack stability and avalanche release probability for spontaneously releasing avalanches. This model accounts, in particular, for the spatial variations of WL shear strength and stress redistribution by elasticity of the slab. We show how avalanche release probability can be computed from release depth distributions, which allows us to study the influence of WL spatial variations and slab properties on slope stability. The importance of smoothing effects by slab elasticity is verified and the crucial impact of spatial variation characteristics on the so‐called knock‐down effect on slope stability is revisited using this model. Finally, critical length values are computed from the simulations as a function of the various model parameters and are compared to field data obtained with propagation saw tests.
Molecular mechanism underlying the impact of vitamin D on disease activity of MS
Authors: Munger Kassandra L. , Köchert Karl , Simon Kelly C. , Kappos Ludwig , Polman Chris H. , Freedman Mark S. , Hartung Hans P. , Miller David H. , Montalbán Xavier , Edan Gilles , Barkhof Frederik , Pleimes Dirk , Sandbrink Rupert , Ascherio Alberto , Pohl Christoph 
Published: August 2014

AbstractObjectiveSome previous studies suggest modest to strong effects of 25‐hydroxyvitamin D (25(OH)D) on multiple sclerosis (MS) activity. The objective of this study was to explore the mechanistic rationale that may explain potential clinical effects of 25(OH)D.MethodsThis study measured serum 25(OH)D levels and global gene expression profiles over a course of up to 2 years in patients starting treatment with interferon beta‐1b (IFNB‐1b) after a clinically isolated syndrome.MSdisease activity was assessed by the number of gadolinium‐enhancing lesions present on repeated magnetic resonance imaging (MRIs).ResultsThe number of gadolinium‐enhancing lesions was highly significantly associated with 25(OH)D levels. Conducting various systems‐level analyses on the molecular level, multiple lines of evidence indicated that 25(OH)D regulates expression dynamics of a large gene–gene interaction system which primarily regulates immune modulatory processes modulatingMSactivity. The vitamin D response element was significantly enriched in this system, indicating a direct regulation of this gene interaction network through the vitamin D receptor. With increasing 25(OH)D levels, resulting regulation of this system was associated with a decrease inMSactivity. Within the complex network of genes that are regulated by 25(OH)D, well‐described targets ofIFNB‐1b and a regulator of sphingosine‐1‐phosphate bioavailability were found. The 25(OH)D effects onMSactivity were additively enhanced byIFNB‐1b.InterpretationHere, we provide mechanistic evidence that an unbalanced 25(OH)D gene expression system may affectMSactivity. Our findings support a potential benefit of monitoring and managing vitamin D levels (e.g., through supplementation) in earlyMSpatients treated withIFN‐beta‐1b.
Cobalt‐Impregnated Magnetite as General Heterogeneous Catalyst for the Hydroacylation Reaction of Azodicarboxylates
Authors: Pérez Juana M. , Ramón Diego J. 
Published: August 2014

AbstractCatalysts consisting of cobalt and nickel impregnated on magnetite have been prepared, characterized and used for the hydroacylation reaction of different azodicarboxylate compounds with aldehydes, using nearly stoichiometric amounts of both reagents in only 3 h. Furthermore, this reaction has been conducted with the smallest amount of catalyst. The cobalt catalyst is stable enough to be removed by magnetic decantation and recycled ten‐fold without any detrimental effect on the results.magnified image
Manganese(III)‐Catalyzed Oxidative Cyclization of Aryl 1‐Cyanoalk‐5‐ynyl Ketone Systems: A Convenient and General Approach to Cyclopenta[b]naphthalene Derivatives
Authors: Wong Ying‐Chieh , Kao Tzu‐Ting , Huang Jing‐Kai , Jhang Yi‐Wun , Chou Ming‐Chen , Shia Kak‐Shan 
Published: August 2014

AbstractA convenient and general approach for cyclopenta[b]naphthalene derivatives containing a structurally diverse functionality at C‐4 position has been successfully developed, whereby manganese(III) acetate plays a key role to facilitate the tandem 5‐exo‐dig and 6‐exo/endo cyclization in an efficient manner. Various functional groups, including trimethyl silyl, aryl, ester, ketone, secondary/tertiary amide, phosphonate and halogen, capped on the terminal acetylenic unit are well tolerated under optimal reaction conditions. It is highly conceivable that this novel [6.6.5] framework formation procedure may have broad synthetic utility in light of its operational simplicity and high yields.magnified image
Enantioselective Intramolecular Hydroamination of Unactivated Alkenes Catalyzed by Mono‐ and Bis(gold) Phosphine Complexes
Authors: Lee Seong Du , Timmerman Jacob C. , Widenhoefer Ross A. 
Published: August 2014

AbstractA 1:2 mixture of (P1)(AuCl)2 [P1=(S)‐DTBM‐MeO‐BIPHEP] and silver tetrafluoroborate (AgBF4) in methanol catalyzes the intramolecular hydroamination of unactivated alkenes with carbamates and ureas to form pyrrolidine derivatives with up to 85% ee.magnified image
Lysosomal pH Rise during Heat Shock Monitored by a Lysosome‐Targeting Near‐Infrared Ratiometric Fluorescent Probe
Authors: Wan Qiongqiong , Chen Suming , Shi Wen , Li Lihong , Ma Huimin 
Published: August 2014

AbstractHeat stroke is a life‐threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome‐targeting near‐infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat‐related pathology.
A novel foaming approach to prepare porous superabsorbent poly(sodium acrylic acid) resins
Authors: Bao Jianshe , Chen Si , Wu Bozhen , Ma Meng , Shi Yanqin , Wang Xu 
Published: August 2014

ABSTRACTA system composed of surfactant and foam stabilizer is used in preparing porous superabsorbent resins (SARs) of poly(sodium acrylic acid) (PAA‐Na), which is obtained by free‐radical solution polymerization of partially neutralized acrylic acid with mechanical agitation of eggbeater. Different types of surfactant, including anionic surfactant sodium n‐dodecyl benzene sulfate (SDBS), cationic surfactant cetyltrimethyl ammonium bromide, and nonionic surfactant alkylphenols poly(oxyethylene) (OP‐10), are used as blowing agent to produce pores by mechanical agitation, and triethanolamine (TEA) is used to act as foam stabilizer agent. The results show that a synergistic effect of SDBS with TEA is obtained and the packing density is decreased, which could be proved by the clearly porous morphology, and the water absorbing capacity of SARs is enhanced. As a result, such method can get PAA‐Na SARs without any organic solvents, which provides an environmentally beneficial way to prepare SARs for hygiene and biomedical products. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41298.
Tear force of physically crosslinked poly(vinyl alcohol) gels with different submicrometer‐scale network structures
Authors: Noh Taegu , Bando Yujiro , Ota Kensuke , Sasaki Saori , Suzuki Atsushi 
Published: August 2014

ABSTRACTPoly(vinyl alcohol) (PVA) gels can be easily prepared by either the freeze‐thawing (FT gel) method or by the cast‐drying (CD gel) method. Although the resulting nanostructured networks of the FT and CD gels are similar, their physical properties are quite different; while CD gels are transparent and elastic, FT gels are opaque and less elastic. Moreover, the tear energy of the FT gels is much greater than that of the CD gels, which is a direct result of micrometer‐scale differences in their network structures. In order to control the distribution of microcrystallites on nano‐ and micrometer scales, FT gels were prepared from PVA solutions with different water contents. As a result, the gel gradually became more transparent as the initial water content was decreased; and accordingly, the tear energy decreased. Tear resistance was improved in the case of FT gels by repeating the number of FT cycles, whereas with CD gels, this was achieved by increasing the gelation temperature. These results indicate that the microscopic network structures are characterized by a micrometer‐scale bundled‐polymer (fibril), which determines the tear energy of FT gels. Simple methods to control the fibril network structure of FT gels using a unidirectional freezing method are presented herein, with the swelling and mechanical properties of modified FT gels discussed in terms of their multiple‐scale network structures. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41356.
Composites based on CB/CF/Ag filled EPDM/NBR rubber blends with high conductivity
Authors: Ding Xuejiao , Wang Jingwen , Zhang Su , Wang Jie , Li Shuqin 
Published: August 2014

ABSTRACTFor many applications of conductive rubbers, it is desirable to endow the conductive rubber with high conductivity at low conductive filler loading. In this work, composites based on ethylene‐propylene‐diene monomer (EPDM) rubber and nitrile‐butadiene rubber (NBR) were prepared using carbon blacks, carbon fibers, and silver powders as fillers. As the weight fraction of silver powder increased, the hardness of composites increased gradually while the tensile strength and elongation at break decreased. SEM revealed that the EPDM/NBR blends exhibited a relatively co‐continuous morphology. The differential scanning calorimetry (DSC) curves reported the EPDM/NBR rubber blends were incompatibility. The thermogravimetry (TG) studies showed that adding a small amount of silver powder could improve the thermal stability of composites. These conductive composites exhibited good electrical property. At room temperature, when the total volume fraction of fillers was 15.20%, the volume resistivity of EPDM/NBR blend was only 0.0058 Ω cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41357.
Energy Prices, Subsidies and Resource Tax Reform in China
Authors: Zhang ZhongXiang 
Published: August 2014

AbstractThe Chinese leadership in November 2013 is determined to embark upon a new wave of comprehensive reforms in China. This is clearly reflected by the key decision of the Third Plenum of the 18th Central Committee of Communist Party of China to assign the market a decisive role in allocating resources. To have the market to play that role, getting the energy prices right is crucial. While the overall trend of China's energy pricing reform since 1984 has been moving towards a more market‐oriented pricing mechanism, the pace and scale of the reform differ across energy types. This article discusses the evolution of price reforms for coal, petroleum products, natural gas and electricity in China, provides some analysis of these energy price reforms, and suggests that few areas of reforms could take place in order to have the market play that decisive role and help China's transition to a low‐carbon economy.
International Institutions and the Rise of Asia
Authors: Drysdale Peter , Willis Sébastien 
Published: August 2014

AbstractThis article applies a game‐theoretical analysis of institutions to the international institutional architecture, of which the G20 is treated as a central element. The article argues that international institutions such as the World Trade Organization or the International Monetary Fund are best understood as mechanisms for coordinating and supporting equilibria in repeated games played among policy‐makers in the world's largest economies. The growth of the emerging economies, particularly in Asia, has altered these games, and there is no guarantee, with these new entrants and new issues that have emerged, that the old equilibrium strategies are still viable. The G20, it is argued, is best understood as an attempt to respond to this change and coordinate play on a new set of globally welfare‐enhancing equilibria in these games.
Crows on the Cradles: Palestinian Mothers at a Frontline Vortex Reflections on the Psychology of Occupation
Authors: Roth Judy , Duaibis Salwa 
Published: August 2014

AbstractPalestinian mothers living in the friction points in East Jerusalem and the West Bank provide critical windows into the traumas that challenge families ensnarled in the vortex of ongoing political violence and living under occupation. Our paper, using interviews of Palestinian mothers, is a view of the abnormal – the violence that infects childhood and parenting, the fight of some mothers for a “real normal”, and the induction into the “new normal”, in which the night‐time incursions, the mapping of communities, the detention of their adolescent sons, the solitary confinements of some, are “accepted” as a rite of passage. Managing terror and its anticipation exhausts and corrodes family functioning and community life. Mothers become inducted into a traumatic vortex, as they struggle to contain the anguish, multiple losses, and the outrage over the dispossession of longings and claims. Our own inescapable countransference, a simultaneous compulsion to understand coupled with an aversion to engage, provided vital information about the stench of violence that permeates these mothers' lives and the terror of losing not only children but one's mind, as well. Copyright © 2014 John Wiley & Sons, Ltd.