bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atmospheric winter response to Arctic sea ice changes in reanalysis data and model simulations
Authors: Jaiser Ralf , Nakamura Tetsu , Handorf Dörthe , Dethloff Klaus , Ukita Jinro , Yamazaki Koji 
Published: June 2016

AbstractThe changes of atmospheric flow patterns related to Arctic Amplification have impacts well beyond the Arctic regional weather and climate system. Here we examine modulations of vertically propagating planetary waves, a major feature of the climate response to Arctic sea ice reduction by comparing the corresponding results of an atmospheric general circulation model with reanalysis data for periods of high and low sea ice conditions. Under low sea ice condition we find enhanced coupling between troposphere and stratosphere starting in November with preferred polar stratospheric vortex breakdowns in February, which then feeds back to the troposphere. The model experiment and ERA‐Interim reanalysis data agree well with respect to temporal and spatial characteristics associated with vertical planetary wave propagation including its precursors. The upward propagating planetary wave anomalies resemble a wave number 1 and 2 pattern depending on region and timing. Since our experimental design only allows influences from sea ice changes and there is a high degree of resemblance between model results and observations, we conclude that sea ice is a main driver of observed winter circulation changes.
EURO‐CORDEX regional climate model analysis for the Greater Alpine Region: Performance and expected future change
Authors: Smiatek Gerhard , Kunstmann Harald , Senatore Alfonso 
Published: June 2016

AbstractSimulations from 13 highly resolved regional climate models run within the Coordinated Downscaling Experiment initiative at 0.11° resolution with boundary forcings from five different Coupled Model Intercomparison Project Phase 5 global models are employed to derive future climate change signal for the Greater Alpine Region (GAR) and four smaller investigation areas. Evaluation statistics include mean temperature and precipitation, frequency of days with precipitation over 1 mm and over 15 mm, 90% quantile of the frequency distribution, and maximum number of consecutive dry days. The evaluation for the period from 1971 to 2000 indicates that the models reproduce spatial seasonal precipitation patterns. In general, the simulations underestimate the seasonal mean temperature and overestimate the mean precipitation values. In GAR the ensemble seasonal mean temperature bias ranges from −0.8 to −1.9°C. The bias in precipitation varies between +14.8% in summer and +41.6% in the winter season. Larger errors are found for other statistics and in the investigated regions. In general, no significant gains in the quality of reproduction of the observed precipitation and temperature statistics compared to previous experiments can be identified. The temperature calculations for 2071–2100 related to the period from 1971 to 2000 in the GAR area show ensemble mean increases in the seasonal mean 2 m temperature of 2.5°C in fall and winter, 2.4°C in summer, and 1.9°C in spring. In the same area, precipitation is simulated to increase up to 12.3% in winter and 5.7% in spring. Only minor changes of the ensemble mean are predicted with +2.3% in fall and −1.7% in summer.
Perchlorate and volatiles of the brine of Lake Vida (Antarctica): Implication for the in situ analysis of Mars sediments
Authors: Kenig Fabien , Chou Luoth , McKay Christopher P. , Jackson W. Andrew , Doran Peter T. , Murray Alison E. , Fritsen Christian H. 
Published: June 2016

AbstractThe cold (−13.4°C), cryoencapsulated, anoxic, interstitial brine of the >27 m thick ice of Lake Vida (Victoria Valley, Antarctica) contains 49 µg · L−1 of perchlorate and 11 µg · L−1 of chlorate. Lake Vida brine (LVBr) may provide an analog for potential oxychlorine‐rich subsurface brine on Mars. LVBr volatiles were analyzed by solid‐phase microextraction (SPME) gas chromatography–mass spectrometry (GC‐MS) with two different SPME fibers. With the exception of volatile organic sulfur compounds, most other volatiles observed were artifacts produced in the GC injector when the thermal decomposition products of oxychlorines reacted with reduced carbon derived from LVBr and the SPME fiber phases. Analysis of MilliQ water with perchlorate (40 µg · L−1) showed low level of organic artifacts, reflecting carbon limitation. In order to observe sample‐derived organic compounds, both in analog samples and on Mars, the molar abundance of reduced carbon in a sample must exceed those of O2 and Cl2 produced during decomposition of oxychlorines. This suggests that the abundance of compounds observed by the Sample Analysis at Mars (SAM) instruments in Sheepbed samples (CB‐3, CB5, and CB6) may be controlled by an increase in the reduced‐carbon/oxychlorine ratio of these samples. To increase chances of in situ detection of Martian organics during pyrolysis‐GC‐MS, we propose that the derivatization agents stored on SAM may be used as an external source of reduced carbon, increasing artificially the reduced‐carbon to perchlorate ratio during pyrolysis, allowing the expression of more abundant and perhaps more diverse Martian organic matter.
Near‐Earth heliospheric magnetic field intensity since 1750: 1. Sunspot and geomagnetic reconstructions
Authors: Owens M. J. , Cliver E. , McCracken K. G. , Beer J. , Barnard L. , Lockwood M. , Rouillard A. , Passos D. , Riley P. , Usoskin I. , Wang Y‐M. 
Published: June 2016

AbstractWe present two separate time series of the near‐Earth heliospheric magnetic field strength (B) based on geomagnetic data and sunspot number (SSN). The geomagnetic‐based B series from 1845 to 2013 is a weighted composite of two series that employ the interdiurnal variability index; this series is highly correlated with in situ spacecraft measurements of B (correlation coefficient, r = 0.94; mean square error, MSE = 0.16 nT2). The SSN‐based estimate of B, from 1750 to 2013, is a weighted composite of eight time series derived from two separate reconstruction methods applied to four different SSN time series, allowing determination of the uncertainty from both the underlying sunspot records and the B reconstruction methods. The SSN‐based composite is highly correlated with direct spacecraft measurements of B and with the composite geomagnetic B time series from 1845 to 2013 (r = 0.91; MSE = 0.24 nT2), demonstrating that B can accurately reconstructed by both geomagnetic and sunspot‐based methods. The composite sunspot and geomagnetic B time series, with uncertainties, are provided as supporting information.
Subduction beneath Laurentia modified the eastern North American cratonic edge: Evidence from P wave and S wave tomography
Authors: Boyce A. , Bastow I. D. , Darbyshire F. A. , Ellwood A. G. , Gilligan A. , Levin V. , Menke W. 
Published: June 2016

AbstractThe cratonic cores of the continents are remarkably stable and long‐lived features. Their ability to resist destructive tectonic processes is associated with their thick (∼250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival‐time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW‐SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two‐stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ∼300 km SE of the Grenville Front, our tomographic models show a near‐vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction‐driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean‐Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation.
Biofilm growth in gravel bed streams controls solute residence time distributions
Authors: Aubeneau A. F. , Hanrahan Brittany , Bolster Diogo , Tank Jennifer 
Published: June 2016

AbstractStreambed substrates harbor a rich biome responsible for biogeochemical processing in riverine waters. Beyond their biological role, the presence of benthic and hyporheic biofilms can play an important role in influencing large‐scale transport of solutes, even for conservative tracers. As biofilms grow and accumulate biomass, they actively interact with and influence surface and subsurface flow patterns. To explore this effect, we conducted experiments at the Notre Dame Linked Ecosystems Experimental Facility in four outdoor streams, each with different gravel beds. Over the course of 20 weeks we conducted transport experiments in each of these streams and observed different patterns in breakthrough curves as biofilms grew on the substrate. Biofilms played a major role in shaping the observed conservative transport patterns. Overall, while the presence of biofilms led to a decreased exchange rate between the fast (mobile) and slow (immobile) parts of the flow domain, water that was exchanged tended to be stored in the slow regions for longer times once biofilms had established. More specifically, we observed enhanced longitudinal dispersion in breakthrough curves as well as broader residence time distributions when biofilms were present. Biofilm colonization over time homogenized transport patterns across the four streams that were originally very distinct. These results indicate that stream biofilms exert a strong control on conservative solute transport in streams, a role that to date has not received enough attention.
N‐Heterocyclic Carbene‐Catalyzed Synthesis of Multi‐Substituted Benzenes from Enals and α‐Cyano‐β‐methylenones
Authors: Zhang Chun‐Lin , Gao Zhong‐Hua , Liang Zhi‐Qin , Ye Song 
Published: June 2016

AbstractAn oxidative NHC‐catalyzed [2+4] annulation of enals and α‐cyano‐β‐methylenones was established for the rapid assembly of multi‐substituted benzenes.magnified image
Fouling Resistance and Physicochemical Properties of Polyamide Thin‐Film Composite Membranes Modified with Functionalized Cyclodextrins
Authors: Mbuli Bhekani S. , Mhlanga Sabelo D. , Mamba Bhekie B. , Nxumalo Edward N. 
Published: June 2016

AbstractThermal and mechanical properties and fouling resistance of polyamide thin‐film composite (PA‐TFC) membranes modified with amino‐cyclodextrins and diethylamino‐cyclodextrins are investigated. It was found that the decomposition temperatures of the modified membranes were 500°C and were not significantly different with those of the unmodified membranes. Differential scanning calorimetry (DSC) studies showed that the modified membranes with heating melting temperatures in the range 112.5–113.8°C were more crystalline than the unmodified membranes due to the presence of cyclodextrin derivatives on the interfacial layer. The crystallization temperatures (Tc) were found to range between 128.75 and 129.03°C and the glass transition temperatures (Tg) ranged between 78.67 and 79.33°C. The modified PA‐TFC membranes were found to have comparable ultimate tensile strengths (UTS) to the unmodified membranes, except for the membranes modified with amino‐β‐CDs, with a UTS of 20.00 ± 0.50 MPa. The PA‐TFC membranes had a lower water uptake percentage due to their enhanced crystallinity. However, these materials had a higher water permeate flux due to the hydrophilic nature of the modified membranes enhanced by the rich hydroxyl groups on the CDs. The modified PA‐TFC membranes also exhibited high MgSO4 salt rejection and fouling resistance capacities compared to unmodified membranes. Different pH levels resulted in different fouling resistance patterns of the membranes. Therefore, the membranes modified with functionalized CDs were thermally and mechanically stable, had enhanced crystallinity, high divalent salt rejection and fouling resistance under different pH conditions.
Cellulose Acetate for Shape Memory Polymer: Natural, Simple, High Performance, and Recyclable
Authors: Bai Yongkang , Liu Yuejun , Wang Qihua 
Published: June 2016

AbstractIn this work, a bio‐shape memory polymer (SMP) with high performance is prepared by using cellulose acetate (CA) as raw material. The materials exhibit good mechanical properties with tensile strength and elongation at break over 46 MPa and 115%, respectively. With hydrogen bond interaction as physically cross‐linked points, the materials also present excellent dual‐shape memory properties with shape fixation and shape recovery ratio of about 99% and 96%, respectively. Moreover, the materials show good triple‐shape memory effect. The recyclability of the materials is also investigated and the results show that the reclaimed samples still hold high mechanical and shape memory properties. With the intrinsic biocompatibility and biodegradation of CA, the materials could be an attractive candidate for applications in smart biomedical devices. Furthermore, the usage of CA as SMP could expand the view of preparing bio‐SMP in future.
Picomole‐Scale Real‐Time Photoreaction Screening: Discovery of the Visible‐Light‐Promoted Dehydrogenation of Tetrahydroquinolines under Ambient Conditions
Authors: Chen Suming , Wan Qiongqiong , Badu‐Tawiah Abraham K. 
Published: June 2016

AbstractThe identification of new photocatalytic pathways expands our knowledge of chemical reactivity and enables new environmentally friendly synthetic applications. However, the development of miniaturized screening procedures/platforms to expedite the discovery of photochemical reactions remains challenging. Herein, we describe a picomole‐scale, real‐time photoreaction screening platform in which a handheld laser source is coupled with nano‐electrospray ionization mass spectrometry. By using this method, we discovered an accelerated dehydrogenation pathway for the conversion of tetrahydroquinolines into the corresponding quinolines. This transformation is readily promoted by an off‐the‐shelf [Ru(bpy)3]Cl2⋅6 H2O complex in air at ambient temperature in direct sunlight, or with the aid of an energy‐saving lamp. Moreover, radical cations and trans‐dihydride intermediates captured by the screening platform provided direct evidence for the mechanism of the photoredox reaction.
Sequential liquefaction of Nicotiana tabacum stems biomass by crude polyhydric alcohols for the production of polyols and rigid polyurethane foams
Authors: Patel Chirag M. , Barot Amit A. , Kumar Sinha Vijay 
Published: June 2016

ABSTRACTIn this work, Nicotiana tabacum stalks and castor oil‐based polyol was synthesized via two step process. Preliminarily, stalks were liquefied using acid catalyst to procure glycol‐glycoside and the optimized conditions for liquefaction of N. tabacum stem's biomass was 150 °C temperature for 180 min time using PTSA as catalyst. Progressively, the glycol‐glycoside obtained from the former step was further reacted with castor oil in the presence of lithium hydroxide to get dark brown‐colored polyol with hydroxyl value was running in between 200 and 400 IOH. Glycol‐glycoside and polyols were characterized by chemical and instrumental methods. Further by employing open‐cup method involving the mixing of polyol and isocyanate adducts, the desired poly urethane rigid foam was obtained. The product was tested for their physical, mechanical, thermal, and morphological characteristics, while the thermal conductivity was in the range of 0.013 to 0.017 Kcal/mh °C. The performed study may yield high quality rigid or semi‐rigid polyurethane foams that are commonly used as insulation materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43974.
Basicity‐based screening of aniline derivative for composite proton exchange membranes
Authors: Sachan Vinay K. , Michael Rajesh A. , Panday Niharika , Nagarale Rajaram K. , Bhattacharya Prashant K. 
Published: June 2016

ABSTRACTThe aim of this study was to find a suitable aniline derivative to develop composite sulfonated poly(ether ether ketone) (SPEEK) membranes and detail evaluation of their physico‐ and electrochemical properties. The hypothesis was high basicity of the aniline derivatives could form good composite membranes with better physicochemical and electrochemical properties. To assess the basicity we measured the zeta potentials of the polymers and correlated them with ion‐exchange capacities, water uptakes, transport numbers, water‐diffusion coefficients, conductivities, and methanol permeabilities. The obtained values of zeta potentials at pH 7 were 6.52, −14.66, −25.17, and −28 for SPEEK/polynaphthalene (PNAPH), SPEEK/polyanisidine (PANIS), SPEEK/polyaniline (PANI), and SPEEK/polyxylindine (PXYL), respectively supports the hypothesis and strongly suggests polyaniline derivative's basicity‐dependent properties. Of the four derivatives (PNAPH, PANIS, PANI, and PXYL), the SPEEK/PXYL composite membrane had the lowest methanol permeability of 1 × 10−4 cm2/s and highest proton conductivity of 161 mS/cm. These values are far better than the neat SPEEK and SPEEK/PANI composite. The suitability of SPEEK/PXYL can be explained by the high basicity of the PXYL composite membrane, which leads to the formation of effective Debye spheres, meaning that the ionic complex can interact with surrounding hydronium ions and form hydrophilic channels resulting in high proton conductivity and low methanol permeability. These results suggest that SPEEK/PXYL is a highly suitable membrane for methanol fuel cells or other electrochemical applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43978.
Short‐term traffic flow prediction with linear conditional Gaussian Bayesian network
Authors: Zhu Zheng , Peng Bo , Xiong Chenfeng , Zhang Lei 
Published: June 2016

SummaryTraffic flow prediction is an essential part of intelligent transportation systems (ITS). Most of the previous traffic flow prediction work treated traffic flow as a time series process only, ignoring the spatial relationship from the upstream flows or the correlation with other traffic attributes like speed and density. In this paper, we utilize a linear conditional Gaussian (LCG) Bayesian network (BN) model to consider both spatial and temporal dimensions of traffic as well as speed information for short‐term traffic flow prediction. The LCG BN allows both continuous and discrete variables, which enables the consideration of categorical variables in traffic flow prediction. A microscopic traffic simulation dataset is used to test the performance of the proposed model compared to other popular approaches under different predicting time intervals. In addition, the authors investigate the importance of spatial data and speed data in flow prediction by comparing models with different levels of information. The results indicate that the prediction accuracy will increase significantly when both spatial data and speed data are included. Copyright © 2016 John Wiley & Sons, Ltd.
Synthesis of bolaform biosurfactants by an engineered Starmerella bombicola yeast
Authors: Van Bogaert Inge N. A. , Buyst Dieter , Martins José C. , Roelants Sophie L. K. W. , Soetaert Wim K. 
Published: June 2016

ABSTRACTBola‐amphiphilic surfactants are molecules with fascinating properties. Their unique configuration consisting of a long hydrophobic spacer connecting two hydrophilic entities renders the molecule more water soluble than the average surfactant, but still allows formation of supramolecular structures. These properties make them extremely suitable for applications in in nanotechnology, electronics, and gene and drug delivery. In general, these compounds are obtained by chemical synthesis. We report here an efficient microbial production process for the fully green synthesis of bolaform surfactants. A sophorolipid‐producing Starmerella bombicola yeast strain was disabled in its sophorolipid acetyltransferase and lactone esterase, which should logically result in synthesis of non‐acetylated acidic sophorolipids; molecules with the classic amphiphilic structure. Surprisingly, also bolaform glycolipids were obtained, with an additional sophorose linked to the free carboxyl end of the acidic sophorolipids as confirmed by MS and NMR analysis. The obtained titers of 27.7 g/L total product are comparable to wild type values, and the novel molecules account for at least 74% of this. Bola‐amphiphile biosynthesis proved to be attributed to the promiscuous activity of both UDP‐glucosyltransferases UGTA1 and UGTB1 from the core sophorolipid pathway, displaying activity toward non‐acetylated intermediates. The absence of acetyl groups seems to trigger formation of bolaform compounds starting from acidic sophorolipids. Hence, wild type S. bombicola produces these compounds only at marginal amounts in general not reaching detection limits. We created a strain knocked‐out in its sophorolipid acetyltransferase and lactone esterase able to produce these novel compounds in economical relevant amounts, opening doors for the application of biological‐derived bolaform structures. Biotechnol. Bioeng. 2016;113: 2644–2651. © 2016 Wiley Periodicals, Inc.
Combinatorial pathway optimization in Escherichia coli by directed co‐evolution of rate‐limiting enzymes and modular pathway engineering
Authors: Lv Xiaomei , Gu Jiali , Wang Fan , Xie Wenping , Liu Min , Ye Lidan , Yu Hongwei 
Published: June 2016

ABSTRACTMetabolic engineering of microorganisms for heterologous biosynthesis is a promising route to sustainable chemical production which attracts increasing research and industrial interest. However, the efficiency of microbial biosynthesis is often restricted by insufficient activity of pathway enzymes and unbalanced utilization of metabolic intermediates. This work presents a combinatorial strategy integrating modification of multiple rate‐limiting enzymes and modular pathway engineering to simultaneously improve intra‐ and inter‐pathway balance, which might be applicable for a range of products, using isoprene as an example product. For intra‐module engineering within the methylerythritol‐phosphate (MEP) pathway, directed co‐evolution of DXS/DXR/IDI was performed adopting a lycopene‐indicated high‐throughput screening method developed herein, leading to 60% improvement of isoprene production. In addition, inter‐module engineering between the upstream MEP pathway and the downstream isoprene‐forming pathway was conducted via promoter manipulation, which further increased isoprene production by 2.94‐fold compared to the recombinant strain with solely protein engineering and 4.7‐fold compared to the control strain containing wild‐type enzymes. These results demonstrated the potential of pathway optimization in isoprene overproduction as well as the effectiveness of combining metabolic regulation and protein engineering in improvement of microbial biosynthesis. Biotechnol. Bioeng. 2016;113: 2661–2669. © 2016 Wiley Periodicals, Inc.