bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of PBL schemes combining the WRF model simulations with scanning water vapor differential absorption lidar measurements
Authors: Milovac Josipa , Warrach‐Sagi Kirsten , Behrendt Andreas , Späth Florian , Ingwersen Joachim , Wulfmeyer Volker 
Published: December 2015

AbstractSix simulations with the Weather Research and Forecasting (WRF) model differing in planetary boundary layer (PBL) schemes and land surface models (LSMs) are investigated in a case study in western Germany during clear‐sky weather conditions. The simulations were performed at 2 km resolution with two local and two nonlocal PBL schemes, combined with two LSMs (NOAH and NOAH‐MP). Resulting convective boundary layer (CBL) features are investigated in combination with high‐resolution water vapor differential absorption lidar measurements at an experimental area. Further, the simulated soil‐vegetation‐atmosphere feedback processes are quantified applying a mixing diagram approach. The investigation shows that the nonlocal PBL schemes simulate a deeper and drier CBL than the local schemes. Furthermore, the application of different LSMs reveals that the entrainment of dry air depends on the energy partitioning at the land surface. The study demonstrates that the impact of processes occurring at the land surface is not constrained to the lower CBL but extends up to the interfacial layer and the lower troposphere. With respect to the choice of the LSM, the discrepancies in simulating a diurnal change of the humidity profiles are even more significant at the interfacial layer than close to the land surface. This indicates that the representation of land surface processes has a significant impact on the simulation of mixing properties within the CBL.
Snow instability patterns at the scale of a small basin
Authors: Reuter Benjamin , Richter Bettina , Schweizer Jürg 
Published: December 2015

AbstractSpatial and temporal variations are inherent characteristics of the alpine snow cover. Spatial heterogeneity is supposed to control the avalanche release probability by either hindering extensive crack propagation or facilitating localized failure initiation. Though a link between spatial snow instability variations and meteorological forcing is anticipated, it has not been quantitatively shown yet. We recorded snow penetration resistance profiles with the snow micropenetrometer at an alpine field site during five field campaigns in Eastern Switzerland. For each of about 150 vertical profiles sampled per day a failure initiation criterion and the critical crack length were calculated. For both criteria we analyzed their spatial structure and predicted snow instability in the basin by external drift kriging. The regression models were based on terrain and snow depth data. Slope aspect was the most prominent driver, but significant covariates varied depending on the situation. Residual autocorrelation ranges were shorter than the ones of the terrain suggesting external influences possibly due to meteorological forcing. To explore the causes of the instability patterns we repeated the geostatistical analysis with snow cover model output as covariate data for one case. The observed variations of snow instability were related to variations in slab layer properties which were caused by preferential deposition of precipitation and differences in energy input at the snow surface during the formation period of the slab layers. Our results suggest that 3‐D snow cover modeling allows reproducing some of the snow property variations related to snow instability, but in future work all relevant micrometeorological spatial interactions should be considered.
The algal lift: Buoyancy‐mediated sediment transport
Authors: Mendoza‐Lera Clara , Federlein Laura L. , Knie Matthias , Mutz Michael 
Published: December 2015

AbstractThe role of benthic algae as biostabilizers of sediments is well‐known, however, their potential to lift and transport sediments remains unclear. Under low‐flow conditions, matured algal mats may detach from the bed and may lift up sediment, thereby causing disturbance to the uppermost streambed sediment. We tested the potential of algal mats to lift sediments in 12 indoor flumes filled with sand (0.2 – 0.8 mm), gravel (2 – 8 mm) or a sand‐gravel mixture (25/75% mass). After four weeks, the algal mats covered about 50% of the flumes area. Due to the accumulation of oxygen gas bubbles in the mats, that developed from high primary production at 4.5 weeks, about half of the algal mats detached from the bed carrying entangled sediments. Both the area covered by algal mats and detached area were similar among sediment types, but the amount of sediment transported tended to be higher for sand and sand‐gravel mixture compared to gravel. Our results reveal that biologically mediated sediment transport mainly depends on the development of a dense filamentous algal matrix, that traps gas bubbles, increasing the mats buoyancy. This novel mechanism of sediment transport will occur in shallow ecosystems during low‐flow periods, with the highest impact for sandy sediments.
Game theory and risk‐based leveed river system planning with noncooperation
Authors: Hui Rui , Lund Jay R. , Madani Kaveh 
Published: December 2015

AbstractOptimal risk‐based levee designs are usually developed for economic efficiency. However, in river systems with multiple levees, the planning and maintenance of different levees are controlled by different agencies or groups. For example, along many rivers, levees on opposite riverbanks constitute a simple leveed river system with each levee designed and controlled separately. Collaborative planning of the two levees can be economically optimal for the whole system. Independent and self‐interested landholders on opposite riversides often are willing to separately determine their individual optimal levee plans, resulting in a less efficient leveed river system from an overall society‐wide perspective (the tragedy of commons). We apply game theory to simple leveed river system planning where landholders on each riverside independently determine their optimal risk‐based levee plans. Outcomes from noncooperative games are analyzed and compared with the overall economically optimal outcome, which minimizes net flood cost system‐wide. The system‐wide economically optimal solution generally transfers residual flood risk to the lower‐valued side of the river, but is often impractical without compensating for flood risk transfer to improve outcomes for all individuals involved. Such compensation can be determined and implemented with landholders' agreements on collaboration to develop an economically optimal plan. By examining iterative multiple‐shot noncooperative games with reversible and irreversible decisions, the costs of myopia for the future in making levee planning decisions show the significance of considering the externalities and evolution path of dynamic water resource problems to improve decision‐making.
Transition of dominant peak flow source from snowmelt to rainfall along the Colorado Front Range: Historical patterns, trends, and lessons from the 2013 Colorado Front Range floods
Authors: Kampf Stephanie K. , Lefsky Michael A. 
Published: December 2015

AbstractThe Colorado Front Range has a large elevation gradient with deep seasonal snowpack in the mountains and limited snow accumulation in the foothills and plains. This study examines how the sources of annual peak flows (snowmelt, rainfall, mixed) change with the fraction of time snow persists on the ground, snow persistence (SP), and whether these sources have changed over time. Sources of peak flows for 20 gaging stations are estimated using a gridded rain and snow model forced with PRISM daily precipitation and both PRISM and TopoWx temperature. The mean snowmelt contribution to peak flow is highly correlated with SP (r2 = 0.86–0.90). Watersheds with SP < 0.3 (low snow, elevation <2000 m) are rainfall‐dominated, and watersheds with SP > 0.7 (persistent snow, elevation >3100 m) are mostly snowmelt‐dominated, with mixed sources between these thresholds. Rainfall runoff peak flows are possible at all elevations, but their likelihood declines with increasing SP. Rainfall runoff from an extreme storm in September 2013 produced the highest annual peaks at many stations, including some snowmelt‐dominated watersheds. Regional Kendall trend tests indicate that the contributions of snowmelt to peak flows and total annual inputs have declined in the mixed source zone. These changes may affect hydrographs, as analyses confirm that snowmelt runoff generally produces more attenuated peaks than rainfall runoff. Discrimination of peak flow source is sensitive to input data and model structure for mixed rain and snowmelt events, and both observation and modeling research are needed to help understand potential runoff changes in these conditions.
Methane occurrence is associated with sodium‐rich valley waters in domestic wells overlying the Marcellus shale in New York State
Authors: Christian Kayla M. , Lautz Laura K. , Hoke Gregory D. , Siegel Donald I. , Lu Zunli , Kessler John 
Published: December 2015

AbstractPrior work suggests spatial parameters (e.g., landscape position, distance to nearest gas well) can be used to estimate the amount of dissolved methane in domestic drinking water wells overlying the deep Marcellus Shale. New York (NY) provides an opportunity to investigate methane occurrence prior to expansion of high‐volume hydraulic fracturing because unconventional gas production is currently banned in the state. We sampled domestic groundwater wells for methane in 2013 (n = 137) across five counties of NY bordering Pennsylvania, and then resampled a subset of those wells in 2014 for methane concentrations and δ13C‐CH4 and δD‐CH4. The majority of waters from wells sampled (77%) had low concentrations of methane (<0.1 mg/L), and only 5% (n = 7) had actionable levels of methane (>10 mg/L). Dissolved methane concentrations did not change as a function of proximity to existing vertical gas wells, nor other parameters indicating subsurface planes of weakness (i.e., faults or lineaments). Methane levels were significantly higher in wells closer to hydrography flow lines, and most strongly correlated to Na‐HCO3 water type. The distribution of methane between Ca‐HCO3 (n = 76) and Na‐HCO3 (n = 23) water types significantly differed (p < 0.01), with median methane concentrations of 0.002 and 0.78 mg/L, respectively. Combined classification of sampled waters based on the dominant water cation, well topographic position, and geologic unit of well completion effectively identified wells with a greater than 50% probability of having methane concentrations exceeding 1 mg/L. Such classification schemes may be useful as a screening tool to assess natural versus gas production‐related sources of methane in domestic wells.
Vocabulary Guessing Strategies
Authors: Gu Yongqi 
Published: December 2015

Abstract
Vocabulary guessing strategies (VGS) refer to the plans and procedures people use to guess the contextual meaning of words, during reading or listening, for the main purpose of comprehension. Guessing is needed when we encounter an unknown word in reading or listening in a second language (L2). In fact, even experienced readers and listeners in their first language (L1) use the guessing strategy all the time. Since many words are homonyms or homographs, part of the comprehension process depends on inferring the correct and appropriate meaning in context.
Grammatical Differences Between
B
ritish and
A
merican
E
nglish
Authors: Jäger Verena , Mondorf Britta 
Published: December 2015

Abstract
Laypersons can often name the odd British–American difference in pronunciation, orthography, or vocabulary, but they are hard put to name grammatical contrasts. Even in linguistics British–American contrasts on the levels of phonology, orthography, and the lexicon have been far more extensively studied than grammatical differences.
Copper(II)/Silver(I)‐Catalyzed Sequential Alkynylation and Annulation of Aliphatic Amides with Alkynyl Carboxylic Acids: Efficient Synthesis of Pyrrolidones
Authors: Zhang Jitan , Li Danyang , Chen Hui , Wang Binjie , Liu Zhanxiang , Zhang Yuhong 
Published: December 2015

AbstractA highly efficient protocol for the synthesis of pyrrolidones by the copper‐catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids is discussed in this paper. A broad range of easily accessible alkynyl carboxylic acids were introduced at the β‐methyl group of aliphatic amides with the assistance of an 8‐aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic CN bond formation within one hour. High selectivity of β‐methyl groups over methylene groups was observed, and the extension of this catalytic system to the activation of methylene CH bonds failed. The substrates with two different groups at the α‐position of the aliphatic amides lead to the formation of diastereoisomers which is determined by 1H NMR spectroscopy. The initially produced products with Z‐configurations can be easily transformed to the corresponding products with E‐configurations by the treatment with dilute p‐toluenesulfonic acid after the reaction. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 CH bonds.magnified image
Click Grafting of Chitosan onto PVC Surfaces for Biomedical Applications
Authors: Mohy Eldin M. S. , Tamer T. M. , Abu Saied M. A. , Soliman E. A. , Madi N. K. , Ragab I. , Fadel I. 
Published: December 2015

ABSTRACTIn this study, polyvinyl chloride (PVC) has been modified through click grafting of chitosan onto its surface. This goal has been achieved using three consecutive steps involving amination, activation, and grafting. Both the amination and chitosan grafting steps were confirmed based on the determination of nitrogen content. The chemical structure of the modified PVC membranes was confirmed by FTIR spectroscopy and thermal analysis, and the morphological changes were monitored by scanning electron microscopy. In addition, the induced physicochemical characteristics were investigated by analyzing the water uptake, mechanical properties, surface roughness, and contact angle. Finally, an evaluation of blood compatibility and protein adsorption characteristics for the chitosan‐g‐PVC membranes is presented.
Semiconducting Group 15 Monolayers: A Broad Range of Band Gaps and High Carrier Mobilities
Authors: Zhang Shengli , Xie Meiqiu , Li Fengyu , Yan Zhong , Li Yafei , Kan Erjun , Liu Wei , Chen Zhongfang , Zeng Haibo 
Published: December 2015

AbstractOptoelectronic applications require materials both responsive to objective photons and able to transfer carriers, so new two‐dimensional (2D) semiconductors with appropriate band gaps and high mobilities are highly desired. A broad range of band gaps and high mobilities of a 2D semiconductor family, composed of monolayer of Group 15 elements (phosphorene, arsenene, antimonene, bismuthene) is presented. The calculated binding energies and phonon band dispersions of 2D Group 15 allotropes exhibit thermodynamic stability. The energy band gaps of 2D semiconducting Group 15 monolayers cover a wide range from 0.36 to 2.62 eV, which are crucial for broadband photoresponse. Significantly, phosphorene, arsenene, and bismuthene possess carrier mobilities as high as several thousand cm2 V−1 s−1. Combining such broad band gaps and superior carrier mobilities, 2D Group 15 monolayers are promising candidates for nanoelectronics and optoelectronics.
Activating a Low Overpotential CO2 Reduction Mechanism by a Strategic Ligand Modification on a Ruthenium Polypyridyl Catalyst
Authors: Johnson Ben A. , Maji Somnath , Agarwala Hemlata , White Travis A. , Mijangos Edgar , Ott Sascha 
Published: December 2015

AbstractThe introduction of a simple methyl substituent on the bipyridine ligand of [Ru(tBu3tpy)(bpy)(NCCH3)]2+ (tBu3tpy=4,4′,4′′‐tri‐tert‐butyl‐2,2′:6′,2′′‐terpyridine; bpy=2,2′‐bipyridine) gives rise to a highly active electrocatalyst for the reduction of CO2 to CO. The methyl group enables CO2 binding already at the one‐electron reduced state of the complex to enter a previously not accessible catalytic cycle that operates at the potential of the first reduction. The complex turns over with a Faradaic efficiency close to unity and at an overpotential that is amongst the lowest ever reported for homogenous CO2 reduction catalysts.
Molekulare Polyarsenide der Seltenerdelemente
Authors: Arleth Nicholas , Gamer Michael T. , Köppe Ralf , Konchenko Sergey N. , Fleischmann Martin , Scheer Manfred , Roesky Peter W. 
Published: December 2015

AbstractDie Reduktion von [Cp*Fe(η5‐As5)] mit [Cp′′2Sm(thf)] (Cp′′=η5‐1,3‐(tBu)2C5H3) führt unter verschiedenen Reaktionsbedingungen zu [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] und [(Cp′′2Sm)2As7(Cp*Fe)]. Bei beiden Verbindungen handelt es sich um die ersten Polyarsenide der Seltenerdmetalle. [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] ist zudem der erste d/f‐Tripeldeckersandwichkomplex mit einem planaren rein anorganischen Mitteldeck. Die zentrale As42−‐Einheit ist isolobal zum 6π‐aromatischen Cyclobutadiendianion (CH)42−. [(Cp′′2Sm)2As7(Cp*Fe)] enthält einen As73−‐Käfig, der eine norbornadienartige Struktur mit zwei kurzen As‐As‐Bindungen hat. DFT‐Rechnungen bestätigen die strukturellen Beobachtungen. Abschätzungen ergaben, dass die As‐As‐Bindungsordnung innerhalb des cyclo‐As4‐Liganden in [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] zwischen einer As‐As‐Einfachbindung und der eines formal aromatischen As42−‐Systems liegt.
Interface Engineering in Two‐Dimensional Heterostructures: Towards an Advanced Catalyst for Ullmann Couplings
Authors: Sun Xu , Deng Haitao , Zhu Wenguang , Yu Zhi , Wu Changzheng , Xie Yi 
Published: December 2015

AbstractThe design of advanced catalysts for organic reactions is of profound significance. During such processes, electrophilicity and nucleophilicity play vital roles in the activation of chemical bonds and ultimately speed up organic reactions. Herein, we demonstrate a new way to regulate the electro‐ and nucleophilicity of catalysts for organic transformations. Interface engineering in two‐dimensional heteronanostructures triggered electron transfer across the interface. The catalyst was thus rendered more electropositive, which led to superior performance in Ullmann reactions. In the presence of the engineered 2D Cu2S/MoS2 heteronanostructure, the coupling of iodobenzene and para‐chlorophenol gave the desired product in 92 % yield under mild conditions (100 °C). Furthermore, the catalyst exhibited excellent stability as well as high recyclability with a yield of 89 % after five cycles. We propose that interface engineering could be widely employed for the development of new catalysts for organic reactions.
Visible‐Light‐Induced Hydrodifluoromethylation of Alkenes with a Bromodifluoromethylphosphonium Bromide
Authors: Lin Qing‐Yu , Xu Xiu‐Hua , Zhang Ke , Qing Feng‐Ling 
Published: December 2015

AbstractBromodifluoromethylphosphonium bromide was solely used as the precursor of difluorocarbene. Herein, an unprecedented visible‐light‐induced hydrodifluoromethylation of alkenes with bromodifluoromethylphosphonium bromide using H2O and THF as hydrogen sources for the synthesis of difluoromethylated alkanes is described. This difluoromethylation is characterized by mild reaction conditions, ready availability of reagents, and excellent functional‐group tolerance.
Palladium‐Catalyzed C(sp2)−H Alkylation of Aldehyde‐Derived Hydrazones with Functionalized Difluoromethyl Bromides
Authors: Prieto Alexis , Melot Romain , Bouyssi Didier , Monteiro Nuno 
Published: December 2015

AbstractA palladium‐catalyzed C(sp2)−H difluoromethylation of aldehyde‐derived hydrazones using bromodifluoromethylated compounds to afford the corresponding functionalized difluoromethylketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a difluoroalkyl radical may be involved in the catalytic cycle. Applications of the methodology to the synthesis of α,α‐difluoro‐β‐ketoesters and α,α‐difluoroketones (RCOCF2H) have been illustrated.
Precision Synchronization Motion Trajectory Tracking Control of Multiple Pneumatic Cylinders
Authors: Meng Deyuan , Tao Guoliang , Li Aimin , Li Wei 
Published: December 2015

AbstractThis paper deals with the synchronized motion trajectory tracking control problem of multiple pneumatic cylinders. An adaptive robust synchronization controller is developed by incorporating the cross‐coupling technology into the integrated direct/indirect adaptive robust control (DIARC) architecture. The position synchronization error and the trajectory tracking error of each cylinder are combined to construct the so‐called coupled position error. The proposed adaptive robust synchronization controller is designed with the feedback of this coupled position error and is composed of two parts: an on‐line parameter estimation algorithm and a robust control law. The former is employed to obtain accurate estimates of model parameters for reducing the extent of parametric uncertainties, while the latter is utilized to attenuate the effects of parameter estimation errors, unmodelled dynamics, and external disturbances. Theoretically, both the position synchronization and trajectory tracking errors will achieve asymptotic convergence simultaneously. Moreover, the effectiveness of the proposed controller is verified by the extensive experimental results performed on a two‐cylinder pneumatic system.
Effects of the Dielectric Constant on the Association Equilibria of Aliphatic Monocarboxylic Acids in Solution
Authors: Conti Filippo , Franconi Cafiero 
Published: December 2015

AbstractMeasurements of shifts of the resonance of the hydroxylic protons of aliphatic monocarboxylic acids in binary and ternary mixtures with aprotic solvents made at a given concentration of acid show a linear dependence of the shift on the reciprocal of the dielectric constant of the medium.Furthermore, interesting regularities in the paramagnetic dilution shifts of the pure acids are evidenced. These shifts are interpreted as an effect of the law of mass action on the complex equilibria in solution. It is shown that the equilibrium between the open and cyclic dimers might be the predominant equilibrium down to low concentrations.