bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surrogate gas prediction model as a proxy for Δ14C‐based measurements of fossil fuel CO2
Authors: Coakley Kevin J , Miller John B , Montzka Stephen A , Sweeney Colm , Miller Ben R 
Published: June 2016

AbstractThe measured14C:12C isotopic ratio of atmospheric CO2(and its associated derived Δ14C value) is an ideal tracer for determination of the fossil fuel derived CO2enhancement contributing to any atmospheric CO2measurement (Cff). Given enough such measurements, independent top‐down estimation of U.S. fossil fuel CO2emissions should be possible. However, the number of Δ14C measurements is presently constrained by cost, available sample volume, and availability of mass spectrometer measurement facilities. Δ14C is therefore measured in just a small fraction of samples obtained by flask air sampling networks around the world. Here we develop a projection pursuit regression (PPR) model to predictCffas a function of multiple surrogate gases acquired within the NOAA/Earth System Research Laboratory (ESRL) Global Greenhouse Gas Reference Network (GGGRN). The surrogates consist of measured enhancements of various anthropogenic trace gases, including CO, SF6, and halocarbon and hydrocarbon acquired in vertical airborne sampling profiles near Cape May, NJ and Portsmouth, NH from 2005 to 2010. Model performance for these sites is quantified based on predicted values corresponding to test data excluded from the model building process. Chi‐square hypothesis test analysis indicates that these predictions and corresponding observations are consistent given our uncertainty budget which accounts for random effects and one particular systematic effect. However, quantification of the combined uncertainty of the prediction due to all relevant systematic effects is difficult because of the limited range of the observations and their relatively high fractional uncertainties at the sampling sites considered here. To account for the possibility of additional systematic effects, we incorporate another component of uncertainty into our budget. Expanding the number of Δ14C measurements in the NOAA GGGRN and building new PPR models at additional sites would improve our understanding of uncertainties and potentially increase the number ofCffestimates by approximately a factor of 3. Provided that these estimates are of comparable quality to Δ14C‐based estimates, we expect an improved determination of fossil fuel CO2emissions.
Shifts in the community structure and activity of anaerobic ammonium oxidation bacteria along an estuarine salinity gradient
Authors: Zheng Yanling , Jiang Xiaofen , Hou Lijun , Liu Min , Lin Xianbiao , Gao Juan , Li Xiaofei , Yin Guoyu , Yu Chendi , Wang Rong 
Published: June 2016

AbstractAnaerobic ammonium oxidation (anammox) is a major microbial pathway for nitrogen (N) removal in estuarine and coastal environments. However, understanding of anammox bacterial dynamics and associations with anammox activity remains scarce along estuarine salinity gradient. In this study, the diversity, abundance, and activity of anammox bacteria, and their potential contributions to total N2 production in the sediments along the salinity gradient (0.1–33.8) of the Yangtze estuarine and coastal zone, were studied using 16S rRNA gene clone library, quantitative polymerase chain reaction assay, and isotope‐tracing technique. Phylogenetic analysis showed a significant change in anammox bacterial community structure along the salinity gradient (P < 0.01), with the dominant genus shifting from Brocadia in the freshwater region to Scalindua in the open ocean. Anammox bacterial abundance ranged from 3.67 × 105 to 8.22 × 107 copies 16S rRNA gene g−1 and related significantly with salinity (P < 0.05). The anammox activity varied between 0.08 and 6.46 nmol N g−1 h−1 and related closely with anammox bacterial abundance (P < 0.01). Contributions of anammox activity to total N loss were highly variable along the salinity gradient, ranging from 5 to 77% and were significantly negatively correlated with salinity (P < 0.01). Sediment organic matter was also recognized as an important factor in controlling the relative role of anammox to total N2 production in the Yangtze estuarine and coastal zone. Overall, our data demonstrated a biogeographical distribution of anammox bacterial diversity, abundance, and activity along the estuarine salinity gradient and suggested that salinity is a major environmental control on anammox process in the estuarine and coastal ecosystems.
Evidence of atmospheric nanoparticle formation from emissions of marine microorganisms
Authors: Sellegri K. , Pey J. , Rose C. , Culot A. , DeWitt H. L. , Mas S. , Schwier A. N. , Temime‐Roussel B. , Charriere B. , Saiz‐Lopez A. , Mahajan A. S. , Parin D. , Kukui A. , Sempere R. , D'Anna B. , Marchand N. 
Published: June 2016

AbstractEarth, as a whole, can be considered as a living organism emitting gases and particles into its atmosphere, in order to regulate its own temperature. In particular, oceans may respond to climate change by emitting particles that ultimately will influence cloud coverage. At the global scale, a large fraction of the aerosol number concentration is formed by nucleation of gas‐phase species, but this process has never been directly observed above oceans. Here we present, using semicontrolled seawater‐air enclosures, evidence that nucleation may occur from marine biological emissions in the atmosphere of the open ocean. We identify iodine‐containing species as major precursors for new particle clusters' formation, while questioning the role of the commonly accepted dimethyl sulfide oxidation products, in forming new particle clusters in the region investigated and within a time scale on the order of an hour. We further show that amines would sustain the new particle formation process by growing the new clusters to larger sizes. Our results suggest that iodine‐containing species and amines are correlated to different biological tracers. These observations, if generalized, would call for a substantial change of modeling approaches of the sea‐to‐air interactions.
Tide and skew surge independence: New insights for flood risk
Authors: Williams Joanne , Horsburgh Kevin J. , Williams Jane A. , Proctor Robert N. F. 
Published: June 2016

AbstractStorm surges are a significant hazard to coastal communities around the world, putting lives at risk and costing billions of dollars in damage. Understanding how storm surges and high tides interact is crucial for estimating extreme water levels so that we can protect coastal communities. We demonstrate that in a tidal regime the best measure of a storm surge is the skew surge, the difference between the observed and predicted high water within a tidal cycle. Based on tide gauge records spanning decades from the UK, U.S., Netherlands, and Ireland we show that the magnitude of high water exerts no influence on the size of the most extreme skew surges. This is the first systematic proof that any storm surge can occur on any tide, which is essential for understanding worst‐case scenarios. The lack of surge generation dependency on water depth emphasizes the dominant natural variability of weather systems in an observation‐based analysis. Weak seasonal relationships between skew surges and high waters were identified at a minority of locations where long‐period changes to the tidal cycle interact with the storm season. Our results allow advances to be made in methods for estimating the joint probabilities of storm surges and tides.
Intercalibration of neutral density measurements for mapping the thermosphere
Authors: Weimer D. R. , Sutton E. K. , Mlynczak M. G. , Hunt L. A. 
Published: June 2016

AbstractThis paper describes a technique for mapping exospheric temperatures, derived from neutral density measurements from the Challenging Mini‐satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites. The Naval Reasearch Laboratory Mass Spectrometer, Incoherent Scatter Radar Extended Model (NRLMSISE‐00) thermosphere model is used for the conversion. Adjustments for each satellite were needed in order for the time‐averaged densities to agree with the model. It was necessary to correct for inexact modeling of the annual and semiannual oscillations in the density, as well as the declining densities during the solar minimum. It was found that a time‐varying perturbation in the atomic oxygen in the model could produce a good agreement at both altitudes. The time series of this oxygen variation was found to have a very high correlation with independent measurements of CO2 emissions measured with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The temperature data are averaged on a spherical grid having equal areas in each pixel, avoiding functional fits that would blur finer details. The use of solar magnetic rather than geographic coordinates enhances the auroral ovals. There are strong elevations in the exospheric temperatures in the polar regions, particularly near the dayside cusp. Spatial filtering with spherical wavelets is used to remove statistical fluctuations, although some details are lost. The exospheric temperature maps are well ordered by the nitric oxide emission measurements from SABER. The technique that is described here could be applied to future improvements of empirical density models, having an accuracy and spatial resolution that is not presently available.
On the origins and timescales of geoeffective IMF
Authors: Lockwood Mike , Owens Mathew J. , Barnard Luke A. , Bentley Sarah , Scott Chris J. , Watt Clare E. 
Published: June 2016

AbstractSouthward interplanetary magnetic field (IMF) in the geocentric solar magnetospheric (GSM) reference frame is the key element that controls the level of space weather disturbance in Earth's magnetosphere, ionosphere, and thermosphere. We discuss the relation of this geoeffective IMF component to the IMF in the geocentric solar ecliptic (GSE) frame, and using the almost continuous interplanetary data for 1996–2015 (inclusive), we show that large geomagnetic storms are always associated with strong southward, out‐of‐ecliptic field in the GSE frame: Dipole tilt effects, which cause the difference between the southward field in the GSM and GSE frames, generally make only a minor contribution to these strongest storms. The time‐of‐day/time‐of‐year response patterns of geomagnetic indices and the optimum solar wind coupling function are both influenced by the timescale of the index response. We also study the occurrence spectrum of large out‐of‐ecliptic field and show that for 1 h averages it is, surprisingly, almost identical in ICMEs (interplanetary coronal mass ejections), around CIRs/SIRs (corotating and stream interaction regions) and in the “quiet” solar wind (which is shown to be consistent with the effect of weak SIRs). However, differences emerge when the timescale over which the field remains southward is considered: for longer averaging timescales the spectrum is broader inside ICMEs, showing that these events generate longer intervals of strongly southward average IMF and consequently stronger geomagnetic storms. The behavior of out‐of‐ecliptic field with timescale is shown to be very similar to that of deviations from the predicted Parker spiral orientation, suggesting the two share common origins.
Decarboxylative Coupling of α‐Keto Acids with ortho‐Phenylenediamines Promoted by an Electrochemical Method in Aqueous Media
Authors: Wang Hai‐Bin , Huang Jing‐Mei 
Published: June 2016

AbstractAn electrochemical method for the decarboxylative coupling of α‐keto acids with ortho‐phenylenediamines was developed. The reaction proceeded smoothly in aqueous solution under air and metal catalyst‐free conditions to afford 2‐substituted benzimidazoles in good yields. Benzothiazoles could also be synthesized by this protocol.magnified image
The Application of N‐Protected 3‐Vinylindoles in Chiral Phosphoric Acid‐Catalyzed [3+2] Cyclization with 3‐Indolylmethanols: Monoactivation of the Catalyst to Vinyliminium
Authors: Fan Tao , Zhang Hong‐Hao , Li Can , Shen Yang , Shi Feng 
Published: June 2016

AbstractA highly enantioselective [3+2] cyclization of 3‐vinylindoles with isatin‐derived 3‐indolylmethanols has been established in the presence of chiral phosphoric acid, which constructed the enantioenriched cyclopenta[b]indole scaffold linking a 3‐vinylindole moiety in generally good yields, considerable diastereoselectivities and high enantioselectivities (up to 93%, >95:5 dr, >99.5:0.5 er). More importantly, this reaction utilized N‐protected 3‐vinylindoles as competent reactants, which confronted the challenge in realizing a successful monoactivation mode of chiral phosphoric acid to vinyliminium in 3‐indolylmethanol‐involved enantioselective transformations. Besides, this protocol also settled the challenge in realizing a highly enantioselective [3+2] cyclization of 3‐vinylindoles with 3‐indolylmethanols, which would serve as a useful strategy for constructing an enantioenriched cyclopenta[b]indole scaffold linking a 3‐vinylindole moiety.magnified image
Potassium tert‐Butoxide‐Promoted Synthesis of 1‐Aminoisoquinolines from 2‐Methylbenzonitriles and Benzonitriles under Catalyst‐Free Conditions
Authors: Feng Jian‐Bo , Wu Xiao‐Feng 
Published: June 2016

AbstractHerein a practical and efficient protocol for preparing a range of aminoisoquinolines is reported. Various aminoisoquinolines were prepared in moderate to good yields from the corresponding 2‐methylbenzonitriles and benzonitriles upon treatment with potassium tert‐butoxide.magnified image
Asymmetric Hydrogenation of 3‐Amido‐2‐arylpyridinium Salts by Triply Chloride‐Bridged Dinuclear Iridium Complexes Bearing Enantiopure Diphosphine Ligands: Synthesis of Neurokinin‐1 Receptor Antagonist Derivatives
Authors: Iimuro Atsuhiro , Higashida Kosuke , Kita Yusuke , Mashima Kazushi 
Published: June 2016

AbstractWe describe a most straightforward synthetic method for preparing neurokinin‐1 (NK1) receptor antagonist derivatives by asymmetric hydrogenation of 3‐amido‐2‐arylpyridinium salts using dinuclear iridium complexes with enantiopure diphosphine ligands, affording the corresponding chiral piperidines in high cis‐diastereoselectivity (>95:5) and moderately high enantioselectivity (up to 86%). Deprotection treatments afforded the NK‐1 receptor antagonist (+)‐CP‐99,994 (83% ee). In addition, we observed unique additive effects of 10‐camphorsulfonic acid in the asymmetric hydrogenation of 3‐amido‐2‐arylpyridinium salts.magnified image
Photoinduced Intramolecular Haloarylation and Hydroarylation of Alkynes
Authors: Xu Dawen , Rios Ramon , Ba Feifei , Ma Dongmei , Gu Guangxin , Ding Aishun , Kuang Yunyan , Guo Hao 
Published: June 2016

AbstractThe cleavage of the aryl C−X bond under UV‐irradiation and its subsequent addition into an intramolecular alkyne moiety have been studied carefully. By simply regulating the addition of electron donor, highly chemoselective intramolecular hydroarylation and haloarylation reactions were achieved, providing efficient methods for the synthesis of 9‐benzylidene‐9H‐fluorene and 9‐(halo(phenyl)methylene)‐9H‐fluorene derivatives.
Radical Changes in Lewis Acid Catalysis: Matching Metal and Substrate
Authors: Bleith Tim , Deng Qing‐Hai , Wadepohl Hubert , Gade Lutz H. 
Published: June 2016

AbstractWhereas the stereochemical rigidity of the coordination sphere of boxmi/CuII catalysts is key to achieving high enantioselectivity in the electrophilic alkylation of β‐ketoesters, this pathway is outperformed by a radical process for the corresponding catalytic transformation of oxindoles, giving rise to racemic products. For the corresponding ZnII catalysts, the selectivity in the latter process is outstanding despite the greater plasticity of the coordination shell. This reaction was thus developed into a highly useful synthetic method, which enabled the conversion of wide range of substrates with high yields and enantioselectivities.
Engineering Gram Selectivity of Mixed‐Charge Gold Nanoparticles by Tuning the Balance of Surface Charges
Authors: Pillai Pramod P. , Kowalczyk Bartlomiej , Kandere‐Grzybowska Kristiana , Borkowska Magdalena , Grzybowski Bartosz A. 
Published: June 2016

AbstractNanoparticles covered with ligand shells comprising both positively and negatively charged ligands exhibit Gram‐selective antibacterial action controlled by a single experimental parameter, namely the proportion of [+] and [−] ligands tethered onto these particles. Gram selectivity is attributed to the interplay between polyvalent electrostatic and non‐covalent interactions that work in unison to disrupt the bacterial cell wall. The [+/−] nanoparticles are effective in low doses, are non‐toxic to mammalian cells, and are tolerated well in mice. These results constitute the first example of rational engineering of Gram selectivity at the (macro)molecular level.
Rapid Synthesis of Cobalt Nitride Nanowires: Highly Efficient and Low‐Cost Catalysts for Oxygen Evolution
Authors: Zhang Yongqi , Ouyang Bo , Xu Jing , Jia Guichong , Chen Shi , Rawat Rajdeep Singh , Fan Hong Jin 
Published: June 2016

AbstractElectrochemical splitting of water to produce hydrogen and oxygen is an important process for many energy storage and conversion devices. Developing efficient, durable, low‐cost, and earth‐abundant electrocatalysts for the oxygen evolution reaction (OER) is of great urgency. To achieve the rapid synthesis of transition‐metal nitride nanostructures and improve their electrocatalytic performance, a new strategy has been developed to convert cobalt oxide precursors into cobalt nitride nanowires through N2 radio frequency plasma treatment. This method requires significantly shorter reaction times (about 1 min) at room temperature compared to conventional high‐temperature NH3 annealing which requires a few hours. The plasma treatment significantly enhances the OER activity, as evidenced by a low overpotential of 290 mV to reach a current density of 10 mA cm−2, a small Tafel slope, and long‐term durability in an alkaline electrolyte.
Modeling of expandable polystyrene expansion
Authors: Hong Yifeng , Fang Xudong , Yao Donggang 
Published: June 2016

ABSTRACTA fundamental understanding of the expansion kinetics of expandable polystyrene (EPS) is crucial for the design and optimization of processes for EPS‐filled syntactic foams. In this study, a general formulation was developed to model EPS expansion. A semi‐analytical solution was obtained on the basis of the case of a single bubble expansion in an infinite matrix. The dimensionless bubble radius and pressure were defined and found to be exponential functions of the dimensionless expansion time. The characteristic bubble expansion time was able to characterize the timescale of the expansion process. The semi‐analytical solution could qualitatively predict the radial expansion of the EPS microsphere observed in a real‐time experiment. To obtain an accurate prediction, a numerical solution was obtained to the model that coupled the nucleation and expansion of multiple bubbles in a finite matrix at various temperatures. The results show that the numerical solution was able to quantitatively predict the radial expansion of EPS. A parameter sensitivity study was performed to examine the effect of each parameter over the expansion process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43886.
Polylactic acid and its blends with petroleum‐based resins: Effects of reprocessing and recycling on properties
Authors: Yarahmadi Nazdaneh , Jakubowicz Ignacy , Enebro Jonas 
Published: June 2016

ABSTRACTEnvironmental and economic reasons make the use of bioplastics and biocomposites increasingly coveted in sectors other than packaging. Recycling of all wasted or rejected durable plastics is highly desired and biobased plastics are no exception. Therefore, the investigation of pre‐ and post‐consumer recycling of products made from biobased plastics is of great interest. Polylactic acid (PLA) and its blends have been chosen for this study because it is an excellent representative of mass‐produced bioplastics for industrial applications. As part of the “Sustainable Recycling of ‘Green’ Plastics” project, the current study addresses the durability issues related to the reprocessing and post‐consumer recycling of a PLA virgin resin and two commercially available blends of PLA namely one with polycarbonate (PC) and one with polyethylene (PE). The materials were investigated using methods that simulate post‐processing and post‐consumer recycling. Accelerated ageing was performed at elevated temperature and humidity to simulate the usage period of the materials. The materials were analyzed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and their mechanical strength was evaluated by tensile and impact testing. The flow properties of the materials were characterized by the melt flow index (MFI). Multiple processing of pure PLA did not affect the impact strength or the glass transition temperature (Tg), but caused crystallization and increase in the MFI, indicating that degradation occurred during processing. DSC thermograms of the blends revealed that the components in the blends were not miscible. Multiple processing of the blends did not significantly affect the elastic modulus of the materials, but affected the elongation at break. The results indicated that multiple processing of the PLA/HDPE blend caused increased dispersion and thus increased elongation at break, while the dominating mechanism in the PLA/PC blend was degradation that caused a decrease in elongation at break. Post‐consumer recycling of the PLA/PC blend was simulated and the results clearly showed that ageing corresponding to one year of use caused a significant degradation of PLA. Pure PLA was severely degraded after only one ageing cycle. Although the PLA/PC blend showed some improved mechanical properties and resistance to degradation compared with pure PLA, one ageing cycle still caused a severe degradation of the PLA and even the PC was degraded as indicated by the formation of small amounts of bisphenol A. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43916.
Heterogeneous Uptake of Gas‐Phase Acetic Acid on the Surface of α‐Al2O3 Particles: Temperature Effects
Authors: Hou Siqi , Tong Shengrui , Zhang Ying , Tan Fang , Guo Yucong , Ge Maofa 
Published: June 2016

AbstractHeterogeneous reactions are thought to play a significant role in the formation of haze, especially in wintertime, which suggests that temperature may affect the heterogeneous formation of organic aerosols. As the most‐abundant carboxylic acid in the Earth′s atmosphere, we chose acetic acid to study the effect of temperature on its heterogeneous reaction with α‐Al2O3 between 248 and 298 K. The products were characterized by in situ DRIFTS, which indicated that lowering the temperature slowed the formation of acetate, but promoted the formation of crystalline acetic acid. Moreover, low temperatures promoted a different reaction mechanism to that at room temperature. Owing to the formation of chain structures at low temperatures, crystalline acetic acid molecules covered the surface active sites on α‐Al2O3, thereby inhibiting the formation of acetate. However, crystalline acetic acid reacted with α‐Al2O3 itself in a sequential manner. Furthermore, the reactive uptake coefficients, active energies, and acetic acid lifetimes at different temperatures were investigated.