bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eruptive timing and 200 year episodicity at 92°W on the hot spot‐influenced Galapagos Spreading Center derived from geomagnetic paleointensity
Authors: Bowles Julie A. , Colman Alice , McClinton J. Timothy , Sinton John M. , White Scott M. , Rubin Kenneth H. 
Published: May 2014

AbstractEruptive timing in mid‐ocean ridge systems is relatively poorly constrained, despite being an important variable in our understanding of many mid‐ocean ridge processes, including volcanic construction; magma recharge, flux, and storage; and the stability of hydrothermal systems and biological communities. Only a handful of absolute eruption chronologies exist, yet they are essential in understanding how eruptive timing varies with important controlling variables. To construct an eruptive history at one location on the Galapagos Spreading Center, we present age determinations derived from geomagnetic paleointensity. To aid interpretation of the paleointensity data, we also present results from on‐bottom magnetic anomaly measurements and forward modeling of topographic‐induced magnetic anomalies. Anomalies may lead to a 1–2 µT bias in flow‐mean paleointensities, which does not significantly affect the overall interpretation. Paleointensity results for the three youngest sampled units are indistinguishable, consistent with the flows being emplaced in relatively rapid succession. Comparisons with models of geomagnetic field behavior suggest these flows were erupted sometime in the past 100–200 years. The fourth sampled unit has a significantly higher paleointensity, consistent with an age of roughly 400 years. The possible bias in paleointensity data allows for ages as young as ∼50 years for the youngest three flows and 200–400 years for the oldest flow. This age distribution demonstrates an episodicity in the emplacement of the largest flows at this location, with a 200–300 year period of relative quiescence between emplacement of the oldest unit and the three youngest units.
Early Eocene carbon isotope excursions: Evidence from the terrestrial coal seam in the Fushun Basin, Northeast China
Authors: Chen Zuoling , Ding Zhongli , Tang Zihua , Wang Xu , Yang Shiling 
Published: May 2014

AbstractA series of transient global warming events between 56 and 50 Ma are characterized by a pronounced negative carbon isotope excursion (CIE). However, the documents of these hyperthermals, such as Eocene Thermal Maximum 2 and H2 events, have come chiefly from marine sediments, and their expression in terrestrial organic carbon is still poorly constrained. Here we yield a high‐resolution carbon isotope record of terrestrial organic material from the Fushun Basin, which displays four prominent CIEs with magnitudes larger than 2.5‰. Based on age constraint and comparisons with deep‐sea records, our data provide the first evidence of the four hyperthermals in coal seams and suggest a global significance of these events. Moreover, the difference of CIE magnitudes between marine and terrestrial records shows a significant linear correlation with the marine carbonate CIE, implying that these events are likely attributable to recurring injections of 13C‐depleted carbon from submarine methane hydrates and/or permafrost.
Ionospheric response to the shock and acoustic waves excited by the launch of the Shenzhou 10 spacecraft
Authors: Ding Feng , Wan Weixing , Mao Tian , Wang Min , Ning Baiqi , Zhao Biqiang , Xiong Bo 
Published: May 2014

AbstractWe used a dense GPS network in China to track the ionospheric response to waves excited by the launch of the rocket that carried Shenzhou 10 spacecraft on 11 June 2013. The long‐distance propagation of shock and acoustic waves were observed on both sides of the rocket's trajectory. On the southern side, the wave structures (characterized by a horizontal extension of ~1400 km and initial amplitudes of 0.3 total electron content unit (TECU) and 0.1 TECU for the shock and acoustic waves, respectively), traveled southwestward a distance of ~1500 km at mean velocities of 1011 m s−1 and 709 m s−1, respectively. On the northern side, northward propagating waves were seen to travel a distance of ~600 km with much smaller amplitudes of less than 0.05 TECU. Subsequent waves with amplitudes of less than 0.02 TECU could also be seen. Clear wave structures were found at a distance of ~600–2000 km from launch site.
Logarithmic radiative effect of water vapor and spectral kernels
Authors: Bani Shahabadi Maziar , Huang Yi 
Published: May 2014

AbstractRadiative kernels have become a useful tool in climate analysis. A set of spectral kernels is calculated using a moderate resolution atmospheric transmission code MODTRAN and implemented in diagnosing spectrally decomposed global outgoing longwave radiation (OLR) changes. It is found that the effect of water vapor on the OLR is in proportion to the logarithm of its concentration. Spectral analysis discloses that this logarithmic dependency mainly results from water vapor absorption bands (0–560 cm−1 and 1250–1850 cm−1), while in the window region (800–1250 cm−1), the effect scales more linearly to its concentration. The logarithmic and linear effects in the respective spectral regions are validated by the calculations of a benchmark line‐by‐line radiative transfer model LBLRTM. The analysis based on LBLRTM‐calculated second‐order kernels shows that the nonlinear (logarithmic) effect results from the damping of the OLR sensitivity to layer‐wise water vapor perturbation by both intra‐ and inter‐layer effects. Given that different scaling approaches suit different spectral regions, it is advisable to apply the kernels in a hybrid manner in diagnosing the water vapor radiative effect. Applying logarithmic scaling in the water vapor absorption bands where absorption is strong and linear scaling in the window region where absorption is weak can generally constrain the error to within 10% of the overall OLR change for up to eightfold water vapor perturbations.
Ensemble downscaling in coupled solar wind‐magnetosphere modeling for space weather forecasting
Authors: Owens M. J. , Horbury T. S. , Wicks R. T. , McGregor S. L. , Savani N. P. , Xiong M. 
Published: May 2014

AbstractAdvanced forecasting of space weather requires simulation of the whole Sun‐to‐Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large‐scale solar wind structures, which can be captured by solar wind models, and small‐scale solar wind “noise,” which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical “downscaling” of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small‐scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model‐independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme.
Physical Activity and Experience of Total Knee Replacement in Patients One to Four Years Postsurgery in the Dominican Republic: A Qualitative Study
Authors: Stenquist Derek S. , Elman Scott A. , Davis Aileen M. , Bogart Laura M. , Brownlee Sarah A. , Sanchez Edward S. , Santiago Adianez , Ghazinouri Roya , Katz Jeffrey N. 
Published: May 2014

ObjectiveMusculoskeletal disorders are the second leading cause of years lived with disability globally. Total knee replacement (TKR) offers patients with advanced arthritis relief from pain and the opportunity to return to physical activity. We investigated the impact of TKR on physical activity for patients in a developing nation.MethodsAs part of the Operation Walk Boston surgical mission program, we interviewed 18 Dominican patients (78% women) who received TKR about their level of physical activity after surgery. Qualitative interviews were conducted in Spanish, and English transcripts were analyzed using content analysis.ResultsMost patients found that TKR increased their participation in physical activities in several life domains, such as occupational or social pursuits. Some patients limited their own physical activities due to uncertainty about medically appropriate levels of joint use and postoperative physical activity. Many patients noted positive effects of TKR on mood and mental health. For most patients in the study, religion offered a framework for understanding their receipt of and experience with TKR.ConclusionOur findings underscore the potential of TKR to permit patients in the developing world to return to physical activities. This research also demonstrates the influence of patients' education, culture, and religion on patients' return to physical activity. As the global burden of musculoskeletal disease increases, it is important to characterize the impact of activity limitation on patients' lives in diverse settings and the potential for surgical intervention to ease the burden of chronic arthritis.
Pericellular Hydrogel/Nanonets Inhibit Cancer Cells
Authors: Kuang Yi , Shi Junfeng , Li Jie , Yuan Dan , Alberti Kyle A. , Xu Qiaobing , Xu Bing 
Published: May 2014

AbstractFibrils formed by proteins are vital components for cells. However, selective formation of xenogenous nanofibrils of small molecules on mammalian cells has yet to be observed. Here we report an unexpected observation of hydrogel/nanonets of a small D‐peptide derivative in pericellular space. Surface and secretory phosphatases dephosphorylate a precursor of a hydrogelator to trigger the self‐assembly of the hydrogelator and to result in pericellular hydrogel/nanonets selectively around the cancer cells that overexpress phosphatases. Cell‐based assays confirm that the pericellular hydrogel/nanonets block cellular mass exchange to induce apoptosis of cancer cells, including multidrug‐resistance (MDR) cancer cells, MES‐SA/Dx5. Pericellular hydrogel/nanonets of small molecules to exhibit distinct functions illustrates a fundamentally new way to engineer molecular assemblies spatiotemporally in cellular microenvironment for inhibiting cancer cell growth and even metastasis.
A Series of Potent CREBBP Bromodomain Ligands Reveals an Induced‐Fit Pocket Stabilized by a Cation–π Interaction
Authors: Rooney Timothy P. C. , Filippakopoulos Panagis , Fedorov Oleg , Picaud Sarah , Cortopassi Wilian A. , Hay Duncan A. , Martin Sarah , Tumber Anthony , Rogers Catherine M. , Philpott Martin , Wang Minghua , Thompson Amber L. , Heightman Tom D. , Pryde David C. , Cook Andrew , Paton Robert S. , Müller Susanne , Knapp Stefan , Brennan Paul E. , Conway Stuart J. 
Published: May 2014

AbstractThe benzoxazinone and dihydroquinoxalinone fragments were employed as novel acetyl lysine mimics in the development of CREBBP bromodomain ligands. While the benzoxazinone series showed low affinity for the CREBBP bromodomain, expansion of the dihydroquinoxalinone series resulted in the first potent inhibitors of a bromodomain outside the BET family. Structural and computational studies reveal that an internal hydrogen bond stabilizes the protein‐bound conformation of the dihydroquinoxalinone series. The side chain of this series binds in an induced‐fit pocket forming a cation–π interaction with R1173 of CREBBP. The most potent compound inhibits binding of CREBBP to chromatin in U2OS cells.
A Natural‐Product Switch for a Dynamic Protein Interface
Authors: Scheepstra Marcel , Nieto Lidia , Hirsch Anna K. H. , Fuchs Sascha , Leysen Seppe , Lam Chan Vinh , in het Panhuis Leslie , van Boeckel Constant A. A. , Wienk Hans , Boelens Rolf , Ottmann Christian , Milroy Lech‐Gustav , Brunsveld Luc 
Published: May 2014

AbstractSmall ligands are a powerful way to control the function of protein complexes via dynamic binding interfaces. The classic example is found in gene transcription where small ligands regulate nuclear receptor binding to coactivator proteins via the dynamic activation function 2 (AF2) interface. Current ligands target the ligand‐binding pocket side of the AF2. Few ligands are known, which selectively target the coactivator side of the AF2, or which can be selectively switched from one side of the interface to the other. We use NMR spectroscopy and modeling to identify a natural product, which targets the retinoid X receptor (RXR) at both sides of the AF2. We then use chemical synthesis, cellular screening and X‐ray co‐crystallography to split this dual activity, leading to a potent and molecularly efficient RXR agonist, and a first‐of‐kind inhibitor selective for the RXR/coactivator interaction. Our findings justify future exploration of natural products at dynamic protein interfaces.
Total Synthesis of the Biphenyl Alkaloid (−)‐Lythranidine
Authors: Gebauer Konrad , Fürstner Alois 
Published: May 2014

AbstractA sequence comprising a ring‐closing alkyne metathesis of a propargyl alcohol derivative, followed by a ruthenium‐catalyzed redox isomerization of the derived cycloalkyne and a transannular aza‐Michael addition allowed the formation of the distinguishing piperidine‐metacyclophane framework of the Lythraceum alkaloid lythanidine in a few high‐yielding steps. This application attests to the excellent functional‐group tolerance of a molybdenum alkylidyne complex endowed with triphenylsilanolate ligands, which enabled the macrocyclization even in the presence of protic functionalities, and thus illustrates the power of contemporary catalytic acetylene chemistry for target‐oriented synthesis.
Be2C Monolayer with Quasi‐Planar Hexacoordinate Carbons: A Global Minimum Structure
Authors: Li Yafei , Liao Yunlong , Chen Zhongfang 
Published: May 2014

AbstractThe design of new materials is an important subject in order to attain new properties and applications, and it is of particular interest when some peculiar topological properties such as reduced dimensionality and rule‐breaking chemical bonding are involved. In this work, we designed a novel two‐dimensional (2D) inorganic material, namely Be2C monolayer, by comprehensive density functional theory (DFT) computations. In Be2C monolayer, each carbon atom binds to six Be atoms in an almost planar fashion, forming a quasi‐planar hexacoordinate carbon (phC) moiety. Be2C monolayer has good stability and is the lowest‐energy structure in 2D space confirmed by a global minima search based on the particle‐swarm optimization (PSO) method. As a semiconductor with a direct medium band gap, Be2C monolayer is promising for applications in electronics and optoelectronics.
Applications of Chiral Phosphine‐Based Organocatalysts in Catalytic Asymmetric Reactions
Authors: Wei Yin , Shi Min 
Published: May 2014

AbstractChiral phosphines are versatile Lewis basic catalysts that are capable of promoting a wide range of asymmetric reactions. In particular, recently designed chiral phosphines based on the concept of bi‐/multifunctionality have been demonstrated to be effective catalysts for many types of asymmetric reactions, such as (aza)‐MBH reactions, cycloaddition reactions, and nucleophilic addition reactions. This short overview summarizes the recent advances in this field and highlights the most‐significant achievements.
Differential Mode Modeling of PMSM for High Frequencies and Harmonic Pulses Calculation
Authors: Adam Ali Ahmed , Gulez Kayhan 
Published: May 2014

AbstractThis work proposes and analyses a model for a cable and permanent magnet synchronous motor to deal with high frequency differential mode components due to IGBT inverter systems. The model permits the study of the differential mode effects separately in the rotor reference frame. The experimental measurements show that the motor differential mode stray capacitances are functions of rotor position. The simulation results of the proposed differential mode circuits, together with the experimental results, show that the level of the differential mode noise currents is of significant value that cannot be ignored. The flow of some differential mode currents in the motor stator windings may contribute to torque pulsations which, require EMI noise filters to be used.
Image‐Based Control for Aerial Manipulation
Authors: Mebarki Rafik , Lippiello Vincenzo 
Published: May 2014

AbstractThis paper presents a new image‐based servo control scheme that endows an unmanned aerial vehicle (UAV) equipped with a robotic arm with the capability of automatically positioning elements on target objects. Through a new formalism, the proposed visual servo scheme controls both theUAVand the manipulator simultaneously. It takes into account the whole system redundancy as well as the peculiarity of under‐actuation related to rotary‐wing crafts. While it controls the system at the velocity level, it makes use of the mobility afforded by theUAVand the dexterity inherent to robot manipulators. The case of large initial errors is explicitly addressed. Results of simulations are reported to verify the effectiveness of the proposed approach.
From waste‐to‐worth: energy, emissions, and nutrient implications of manure processing pathways
Authors: Aguirre‐Villegas Horacio Andres , Larson Rebecca , Reinemann Douglas J. 
Published: May 2014

AbstractFour manure processing pathways are evaluated to provide a system‐level understanding of their impacts on different sustainability indicators. In particular we look at how solid‐liquid separation (SLS), anaerobic digestion (AD), and AD + SLS affect depletion of fossil fuels (DFF), nutrient balances, global warming potential (GWP), and ammonia emissions when compared to the base‐case (BC) pathway of direct land application. Lifecycle sustainability assessment techniques are applied to develop inventory data and model a Wisconsin dairy farm. For the BC, net GWP is 101.2 kg CO2‐eq, DFFS is 106.1 MJ, ammonia emissions are 2.62 kg, and nitrogen availability is 2.45 kg per ton of excreted manure. Net GWP is reduced in all pathways compared to BC by 19% for SLS, 48% for AD, and 47% for AD + SLS. DFF is reduced by 43% for AD and 40% for AD + SLS, but increased by 13% for SLS. Ammonia emissions are increased in all pathways by 2% for SLS, 40% for AD, and 44% for AD + SLS. Nitrogen availability remains the same in SLS but decreases in AD and AD + SLS due to higher ammonia volatilization, which could be reduced by injecting manure. Ratios of fossil energy (FERAD) and energy return on investment (EROIAD) of 3.7 and 0.98–1.8 are determined for AD pathways, compared to FER of 0.29 and EROI of 0.27 for grid electricity. When allocating results to specific outputs, variability can be reduced by applying system subdivision and allocation. Sensitivity analyses highlight the importance of reducing emissions during manure storage and the influence of changes in fertilizer and sand bedding. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
Search, engineering, and applications of new oxidative biocatalysts
Authors: Martínez Angel T. , Ruiz‐Dueñas Francisco J. , Gutiérrez Ana , del Río José C. , Alcalde Miguel , Liers Christiane , Ullrich René , Hofrichter Martin , Scheibner Katrin , Kalum Lisbeth , Vind Jesper , Lund Henrik 
Published: May 2014

AbstractMost industrial enzymes are hydrolases, such as glycosidases and esterases. However, oxidoreductases have an unexploited potential for substituting harsh (and scarcely selective) chemical processes. A group of basidiomycetes are the only organisms degrading the aromatic lignin polymer, enabling the subsequent use of plant polysaccharides. Therefore, these fungi and their ligninolytic peroxidases are the biocatalysts of choice for industrial delignification and oxidative biotransformations of aromatic and other organic compounds. The latter also include oxygenation reactions, which are catalyzed with high regio/stereo selectivity by fungal peroxygenases. In search for novel and more robust peroxidases/peroxygenases, basidiomycetes from unexplored habitats were screened, and hundreds of genes identified in basidiomycete genomes (in collaboration with the DOE JGI). The most interesting genes were heterologously expressed, and the corresponding enzymes structurally‐functionally characterized. The information obtained enabled us to improve the enzyme operational and catalytic properties by directed mutagenesis. However, the structural‐functional relationships explaining some desirable properties are not established yet and, therefore, their introduction was addressed by ‘non‐rational’ directed evolution. Then, over 100 oxidative biotransformations were analyzed. Among them, it is noteworthy to mention the regio/stereo selective hydroxylation of long/short‐chain alkanes (a chemically challenging reaction), epoxidation of alkenes, and production of hydroxy‐fatty acids. Concerning aromatic oxygenations, the regioselective hydroxylation of flavonoids, and stereoselective hydroxylation/epoxidation of alkyl/alkenyl‐benzenes were among the most remarkable reactions, together with enzymatic hydroxylation of benzene (as an alternative for harsh chemical process). Finally, peroxidases and peroxygenases also showed a potential as delignification biocatalysts and in the decolorization of contaminant dyes from textile industries. © 2014 The Authors. Biofuels, Bioproducts and Biorefi ning published by Society of Chemical Industry and John Wiley & Sons, Ltd.
Magnetic Superhydrophobic Polymer Nanosphere Cage as a Framework for Miceller Catalysis in Biphasic Media
Authors: Zheng Zhi , Wang Jianli , Chen Hualiang , Feng Linbin , Jing Ren , Lu Meizhen , Hu Bao , Ji Jianbing 
Published: May 2014

AbstractThis study demonstrated the use of a magnetic superhydrophobic polymer nanosphere cage derived from a Pickering emulsion as a framework for miceller catalysis in biphasic media. We designed this system through the covalent stabilisation of active site (2,2,6,6‐tetramethylpiperidine 1‐oxyl)‐grafted amphiphiles onto the magnetic hydrophobic core to form a micelle‐like architecture and used it as a Pickering emulsifier to develop a new kind of micelle‐catalysed biphasic system. The catalysis results reveal that these fixed micelle‐tethered 2,2,6,6‐tetramethylpiperidine 1‐oxyl catalysts demonstrate much higher activity than their soluble counterparts in the biphasic Montanari oxidation of alcohols, which could be due to the unique properties of Pickering emulsion and miceller catalysis. In addition, the excellent magnetic response ensures the efficient recycling of the catalyst by magnetic decantation. The catalyst can be recycled at least 10 times without significant loss of activity or degradation of magnetic susceptibility. Moreover, this study demonstrates that this new Pickering emulsion‐based and micelle‐catalysed biphasic system is technically simple and practically applicable.