bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical simulation of atmospheric microbursts
Authors: Ferrero E. , Mortarini L. , Manfrin M. , Solari M. , Forza R. 
Published: May 2014

AbstractA laboratory simulation of atmospheric microbursts is presented. The physical model of the atmospheric phenomenon is reproduced at a reduced scale in a rotating tank (TURLab, Italy), the similitude is based on the Froude number. Different experiments were carried out varying the Rossby number, and the analysis of four significant cases is presented. The velocity, vorticity, and turbulent kinetic energy fields are evaluated together with the swirling strength analysis. The comparison with the natural prototype is eventually shown and discussed.
Scales and drivers of temporal pCO2 dynamics in an Alpine stream
Authors: Peter Hannes , Singer Gabriel A. , Preiler Christian , Chifflard Peter , Steniczka Gertraud , Battin Tom J. 
Published: May 2014

AbstractThe role of inland waters for the global carbon cycle is now recognized and evidence increasingly suggests that stream ecosystems disproportionately contribute to the carbon cycle. Understanding the dynamics and drivers of stream water partial pressure of CO2 (pCO2) and CO2 evasion fluxes from streams to the atmosphere is imperative for assessing the role of climate change on the carbon cycle in stream ecosystems. Monitoring pCO2 over 3 years, we here report on the seasonal, diurnal, and event‐driven dynamics of pCO2 in the hyporheic zone and stream water of an Alpine stream and assess possible drivers of these dynamics. Our findings suggest that both catchment‐derived CO2 delivered by shallow groundwater into the stream and in‐stream respiration continuously build up pCO2 in the hyporheic zone. Depending on stream water temperature and assumedly on primary production (inferred from photosynthetically active radiation), hyporheic CO2 contributes to stream water pCO2 and ultimately to CO2 outgassing to the atmosphere. Diurnal patterns of stream water pCO2 increasingly built up during extended base flow and streambed‐scouring storms caused the collapse of these diurnal patterns. Post storm recovery of the diurnal pCO2 patterns was generally rapid. Our findings suggest that decreasing gas exchange velocity related to receding discharge drives recovery dynamics. We found that average CO2 outgassing fluxes during night exceeded those during day by up to 1.8 times. Our study highlights temperature and hydrology—key components of climate change—as major drivers of pCO2 dynamics in Alpine streams. They also underscore the necessity to consider day‐night differences in CO2 outgassing fluxes to properly establish carbon budgets and regional estimates of CO2 outgassing to the atmosphere.
Bayesian hierarchical approach and geophysical data sets for estimation of reactive facies over plume scales
Authors: Wainwright Haruko M. , Chen Jinsong , Sassen Douglas S. , Hubbard Susan S. 
Published: May 2014

AbstractA stochastic model is developed to integrate multiscale geophysical and point data sets for characterizing coupled subsurface physiochemical properties over plume‐relevant scales, which is desired for parameterizing reactive transport models. We utilize the concept of reactive facies, which is based on the hypothesis that subsurface units can be identified that have distinct reactive‐transport‐property distributions. To estimate and spatially distribute reactive facies and their associated properties over plume‐relevant scales, we need to (1) document the physiochemical controls on plume behavior and the correspondence between geochemical, hydrogeological, and geophysical measurements; and (2) integrate multisource, multiscale data sets in a consistent manner. To tackle these cross‐scale challenges, we develop a hierarchical Bayesian model to jointly invert various wellbore and geophysical data sets that have different resolutions and spatial coverage. We use Markov‐chain Monte‐Carlo sampling methods to draw many samples from the joint posterior distribution and subsequently estimate the marginal posterior distribution of reactive‐facies field and their associated reactive transport properties. Synthetic studies demonstrate that our method can successfully integrate different types of data sets. We tested the framework using the data sets collected at the uranium‐contaminated Savannah River Site F‐Area, including wellbore lithology, cone penetrometer testing, and crosshole and surface seismic data. Results show that the method can estimate the spatial distribution of reactive facies and their associated reactive‐transport properties along a 300 m plume centerline traverse with high resolution (1.2 m by 0.305 m).
Advection of baroclinic eddies by depth mean flow
Authors: Klocker Andreas , Marshall David P. 
Published: May 2014

AbstractObserved zonal propagation speeds of nonlinear eddies, derived using an eddy tracking algorithm, are compared with the classical long Rossby wave speed, Doppler shifted by just the depth mean velocity, the latter obtained from annual mean hydrography and an ocean atlas. Despite neglecting any Doppler shift from baroclinic background flows, the correspondence between observed eddy propagation speeds and theoretical long Rossby wave phase speeds is improved in the Antarctic Circumpolar Current region, where both show eastward propagation at speeds of 1–3 cm s−1, although the observed eastward eddy propagation speeds are systematically lower than the predicted Rossby wave phase speeds.
Discontinuities in the magnetic field near Enceladus
Authors: Simon Sven , Saur Joachim , van Treeck Shari C. , Kriegel Hendrik , Dougherty Michele K. 
Published: May 2014

AbstractThe plasma interaction of Saturn's icy moon Enceladus generates a hemisphere coupling current system that directly connects the giant planet's northern and southern polar magnetosphere. Based on Cassini magnetometer observations from all 20 targeted Enceladus flybys between 2004 and 2014, we study the magnetic field discontinuities associated with these hemisphere coupling currents. We identify a total number of 11 events during which the magnetic field was discontinuous at the surface of the Enceladus flux tube (defined by the bundle of magnetic field lines tangential to the solid body of the moon). A minimum variance analysis is applied to calculate the surface normals of these discontinuities. In agreement with theoretical expectations, the normals are found to be perpendicular to the surface of the Enceladus flux tube. The variation of the hemisphere coupling currents with Enceladean longitude leaves a clear imprint in the strengths of the observed magnetic field jumps as well.
Channel networks within lava flows: Formation, evolution, and implications for flow behavior
Authors: Dietterich Hannah R. , Cashman Katharine V. 
Published: May 2014

AbstractNew high‐resolution maps of Hawaiian lava flows highlight complex topographically controlled channel networks. Network geometries range from distributary systems dominated by branching around local obstacles, to tributary systems constricted by topography. We combine 2‐D network analysis tools developed for river systems and neural networks with 3‐D lidar morphologic analysis and historical records of flow emplacement to investigate both the origins of channel networks and their influence on flow morphology and behavior. We find that network complexity is a function of underlying slope and that the degree of flow branching, network connectivity, and longevity of individual channels all influence the final flow morphology (flow and channel widths and levee heights). Furthermore, because channel networks govern the distribution of lava supply within a flow, changes in the channel topology can dramatically alter the effective volumetric flux in any one branch, which affects both flow length and advance rate. Specifically, branching will slow and shorten flows, while merging can accelerate and lengthen them. Consideration of channel networks is thus important for predicting lava flow behavior and mitigating flow hazards with diversion barriers. Observed relationships between network geometry, flow parameters, and morphology also offer insight into the interpretation of these features elsewhere on Earth and other terrestrial planets.
Testing hypothesized predictors of immune activation in tanzanian infants and children: Community, household, caretaker, and child effects
Authors: Hadley Craig , Decaro Jason A. 
Published: May 2014

ObjectivesThere is increasing interest in the epidemiology of immune activation among young children because of the links with mortality and growth. We hypothesized that infant and child inflammation, as measured by elevated C‐reactive protein (CRP), would be associated with household assets, household size, measures of sanitation, and food insecurity. We also hypothesized that children in the poorest households and with elevated CRP would show evidence of growth faltering.MethodsA nationally representative cross‐sectional study of Tanzania children 6–59 months of age. Survey data, anthropometrics, and dried blood spots were available for 1,387 children. Measures of elevated CRP (CRP ≥ 1.1 mg/l) were used to assess inflammation.ResultsFifty‐four percent of the sample had CRP ≥ 1.1 mg/l. In bivariate analyses, several measures of sanitation were associated with elevated CRP but in multiple regression models only age, sex, literacy, maternal reports of illness, household size, and living in the wealthiest households predicted CRP. There were no associations between elevated CRP and any measure of child growth.ConclusionsAmong children in Tanzania, a single elevated CRP does not predict poor growth functioning. Elevated CRP is associated with individual, caretaker, household, and community‐level variables. Future work should strive to measure local biologies in more nuanced ways. Am. J. Hum. Biol. 26:523–529, 2014. © 2014 Wiley Periodicals, Inc.
Synthesis of Tetrahydropyran/Tetrahydrofuran‐Containing Macrolides by Palladium‐Catalyzed Alkoxycarbonylative Macrolactonizations
Authors: Bai Yu , Davis Dexter C. , Dai Mingji 
Published: May 2014

AbstractA novel Pd‐catalyzed cascade alkoxycarbonylative macrolactonization to construct tetrahydropyran/tetrahydrofuran‐containing bridged macrolactones in one step from alkendiols is described. Products with various ring sizes and substituents were obtained. Challenging macrolactones involving tertiary alcohols were synthesized smoothly as well. Mechanistically, experimental evidence to support a trans‐oxypalladation step has been provided. The method was applied to the synthesis of potent anticancer compound 9‐demethylneopeltolide.
Neural‐Adaptive Control and Nonlinear Observer for Waste‐To‐Energy Boilers
Authors: Mahmoodi Takaghaj S. , Macnab C.J.B. , Westwick D. , Boiko I. 
Published: May 2014

AbstractThis paper looks at the problem of controlling an incinerator that burns waste gas to generate power. The system is modelled as a standard utility boiler using one known and one unknown (waste) fuel input. Standard linear controls have trouble dealing with large variations in the waste input, and in practice boiler shutdowns can occur. In this work, a nonlinear adaptive control design accounts for uncertainty in the plant parameters, and an adaptive neural‐network estimates the effect of the waste input. Since a linear observer design cannot guarantee convergence away from a set point, a novel nonlinear observer design provides estimates of the states. The observer design uses fictitious states to estimate nonlinear terms in the observer dynamics. The analysis guarantees Lyapunov stability, thus the observer bounds depend on the accuracy of the observer initial conditions. Simulation results show the proposed method can obtain accurate performance and stability, improving over results obtained withproportional–integral control.
Amplifier Gain Tuning‐Based Slotine‐Li Adaptive Manipulator Control
Authors: Yih Chih‐Chen 
Published: May 2014

AbstractExploiting the linear parameterization and skew‐symmetric properties from the robot model, the Slotine‐Li adaptive control cannot directly be implemented in robot control because the control torque is produced by actuators with electrical drives and power amplifiers. Without considering the actuator dynamics and amplifier gains, the adaptive control can deteriorate in performance and the stability can be violated for the robot manipulators. This paper proposes a simple and novel approach that can represent the effects of actuators with electrical drives by a constant gain from the control signal to the torque and retain the Slotine‐Li adaptive control scheme by achieving a balance between actuator modeling and control implementation. Incorporating the adaptive tuning of the amplifier gain, we extend the adaptive control algorithm proposed by Slotine and Li. We explicitly define the error of amplifier gain, and we show from Lyapunov analysis that the estimation error is bounded. In the simulation, we numerically verify the effectiveness of our approach and the improved performance over the non‐adaptive amplifier gain algorithm.
Microbubble‐mediated sonoporation for highly efficient transfection of recalcitrant human B‐ cell lines
Authors: Ling Yong Charlene Li , Siak‐Wei Ow Dave , Tandiono Tandiono , Mei Heng Lisa Li , Kwok‐Keung Chan Ken , Ohl Claus‐Dieter , Klaseboer Evert , Ohl Siew‐Wan , Boon‐Hwa Choo1 Andre 
Published: May 2014

AbstractSonoporation has not been widely explored as a strategy for the transfection of heterologous genes into notoriously difficult‐to‐transfect mammalian cell lines such as B cells. This technology utilizes ultrasound to create transient pores in the cell membrane, thus allowing the uptake of extraneous DNA into eukaryotic and prokaryotic cells, which is further enhanced by cationic microbubbles. This study investigates the use of sonoporation to deliver a plasmid encoding green fluorescent protein (GFP) into three human B‐cell lines (Ramos, Raji, Daudi). A higher transfection efficiency (TE) of >42% was achieved using sonoporation compared with <3% TE using the conventional lipofectamine method for Ramos cells. Upon further antibiotic selection of the transfected population for two weeks, we successfully enriched a stable population of GFP‐positive Ramos cells (>70%). Using the same strategy, Raji and Daudi B cells were also successfully transfected and enriched to 67 and 99% GFP‐positive cells, respectively. Here, we present sonoporation as a feasible non‐viral strategy for stable and highly efficient heterologous transfection of recalcitrant B‐cell lines. This is the first demonstration of a non‐viral method yielding transfection efficiencies significantly higher (42%) than the best reported values of electroporation (30%) for Ramos B‐cell lines.
Effects of Metal Promotion on the Performance of CuZnAl Catalysts for Alcohol Synthesis
Authors: Beiramar Jorge M. , Griboval‐Constant Anne , Khodakov Andrei Y. 
Published: May 2014

AbstractA series of CuZnAl catalysts modified with different promoters (Fe, Co, Ru, Zr, Mo, Mg, Mn, and Cr) have been prepared through co‐precipitation, characterised by applying a combination of techniques, and tested for carbon monoxide hydrogenation. Cu reducibility in CuZnAl catalysts was affected by the addition of promoters. The ease of Cu reduction in the promoted catalysts leads to more active catalysts for the hydrogenation of carbon monoxide and the production of C2+ alcohols, whereas lower catalytic activity was observed over less reducible catalysts. The promotion of CuZnAl catalysts even with small amounts of Cr, Mn, and Fe resulted in a significant modification in the reaction selectivity. The Fe‐containing catalyst demonstrated a dramatic increase in carbon monoxide conversion and C2+ alcohol productivity (30 mg g${{{- 1\hfill \atop {\rm cat}\hfill}}}$ h−1).
Application of the Electrodiffusion Method to Measure Wall Shear Stress: Integrating Theory and Practice
Authors: Böhm Lutz , Jankhah Sepideh , Tihon Jaroslav , Bérubé Pierre R. , Kraume Matthias 
Published: May 2014

AbstractThe electrodiffusion method has been used in fluid dynamic research for the past 50 years. It allows the measurement of wall shear stress, a crucial parameter, e.g., for the cleaning of membrane modules used in water filtration. Various authors have published articles dealing with the theory behind this technique. But no paper collects all the knowledge assembled over five decades of application. Here, comprehensive summary of the theory of steady flow, unsteady flow, and transient voltage step experiments is given. Factors influencing the accuracy of the measurements are discussed. Furthermore, a new approach to calibrate the system from voltage step experiments is introduced, and practical issues related to its application in flow measurements are discussed for an exemplary signal response to a near‐wall flow.
Stabilizing Lead Cathodes with Diammonium Salt Additives in the Deoxygenation of Aromatic Amides
Authors: Edinger Carolin , Grimaudo Valentine , Broekmann Peter , Waldvogel Siegfried R. 
Published: May 2014

AbstractLead is efficiently protected against cathodic corrosion by the addition of diammonium salts in the electrolyte. The cationic coating of the cathode allows the efficient electroreduction of benzamides to benzylamines. The electrochemical deoxygenation of the amide is achieved without the use of oxophilic agents or sacrificial anodes. The surface of the lead cathode stays smooth and the cathode can be reused for multiple runs, providing <2.5 ppm of the crude product. Cyclic voltammetry studies reveal a shift in the onset potential of the hydrogen evolution reaction by −157 mV.
Elucidating the 2D Magnetic Topology of the ‘Metal–Radical’ TTTA⋅Cu(hfac)2 System
Authors: Vela Sergi , Sopena Arturo , Ribas‐Arino Jordi , Novoa Juan J. , Deumal Mercè 
Published: May 2014

AbstractThe TTTA⋅Cu(hfac)2 polymer (1; in which TTTA=1,3,5‐trithia‐2,4,6‐triazapentalenyl, and hfac=(1,1,1,5,5,5)‐hexafluoroacetylacetonate) is one of the most prominent examples of the rational use of the ‘metal–radical’ synthetic approach to achieve ferromagnetic interactions. Experimentally, the magnetic topology of 1 could not be fully deciphered. Herein, the first‐principles bottom‐up procedure was applied to elucidate the nature and strength of the magnetic JAB exchange interactions present in 1. The computed JAB values give rise to a 2D magnetic topology of ferromagnetic dimers (+11.9 cm−1) coupled through weaker antiferromagnetic interactions (−3.0 and −3.2 cm−1) in two different spatial directions. The hitherto unknown origin of the antiferromagnetic interdimer interactions is thus unveiled. By using the 2D magnetic topology, the agreement between calculated and experimental χT(T) data is extraordinary. In the metal–radical TTTA⋅Cu(hfac)2 compound, the computational model transcends the local dimer cluster model owing to strong interactions between metal centers and organic radicals, thereby creating a de facto biradical. In addition, it is shown that the magnetic topology cannot be inferred from the polymeric [TTTA⋅⋅⋅Cu(hfac)2]n crystal motif, that is, from its chemical coordination pattern. Instead, one should think in terms of magnetic building blocks, namely, the de facto biradicals.
Nanocomposite Incorporating V2O5 Nanowires and Gold Nanoparticles for Mimicking an Enzyme Cascade Reaction and Its Application in the Detection of Biomolecules
Authors: Qu Konggang , Shi Peng , Ren Jinsong , Qu Xiaogang 
Published: May 2014

AbstractArtificial enzyme mimics are a current research interest, and many nanomaterials have been found to display enzyme‐mimicking activity. However, to the best of our knowledge, there have not hitherto been any reports on the use of pure nanomaterials to construct a system capable of mimicking an enzyme cascade reaction. Herein, we describe the construction of a novel nanocomposite consisting of V2O5 nanowires and gold nanoparticles (AuNPs) through a simple and facile chemical method, in which V2O5 and AuNPs possess intrinsic peroxidase and glucose oxidase (GOx)‐like activity, respectively. Results suggest that this material can mimic the enzyme cascade reaction of horseradish peroxidase (HRP) and GOx. Based on this mechanism, a direct and selective colorimetric method for the detection of glucose has been successfully designed. Because single‐strand and double‐strand DNA (ssDNA and dsDNA) have different deactivating effects on the GOx‐like activity of AuNPs, the sensing of target complementary DNA can also be realized and disease‐associated single‐nucleotide polymorphism of DNA can be easily distinguished. Our study opens a new avenue for the use of nanomaterials in enzyme mimetics, and holds promise for the further exploration of nanomaterials in creating alternative catalytic systems to natural enzymes.
The Nucleophilicity of the Oxygen Functional Groups on Carbon Materials: A DFT Analysis
Authors: Li Bo , Su DangSheng 
Published: May 2014

AbstractThe nucleophilicity of the five different oxygen functional groups (carboxyl, diketone, ketone, lactone, and quinone) on the graphene are evaluated by DFT calculations. Two different methods are employed to obtain three different reactivity descriptors, namely, sk−, wk−, and sk−/sk+. The calculations indicate that the quinone group is the most nucleophilic site among the investigated ones. The diketone and ketone are much less active than the quinone group toward an electrophilic attack. This judgment is further supported by Ag+‐binding calculations, which mimics an electrophilic attack. In addition, the carboxyl and lactone groups at a zigzag‐terminated edge show nucleophilic ability that is comparable to that of diketones. The current work lays the basis for future studies on the redox property of carbon catalysis and its implications in catalytic reactions.
Defects in Surface Chemistry—Reductive coupling of Benzaldehyde on Rutile TiO2(110)
Authors: Clawin Peter M. , Friend Cynthia M. , Al‐Shamery Katharina 
Published: May 2014

AbstractThe surface chemistry of oxygen and oxygenates on Rutile TiO2(110) is of great interest for various applications such as heterogeneous catalysis and photo catalysis. Though it is generally accepted that surface defects are active sites, the role of subsurface defects is under debate. We have therefore investigated the influence of the bulk defect density on the reductive coupling of benzaldehyde to stilbene as a model system. Using IRRAS we identify stilbene diolate as a reduction intermediate. The concentration of this intermediate is proportional to the bulk defect density, whereas adsorption of benzaldehyde at lower temperatures is not affected, which indicates a dominant role of Ti interstitials at temperatures above 400 K.
A Study on the Growth of Cr2O3 in Ordered Mesoporous Silica and Its Replication
Authors: Grewe Tobias , Deng Xiaohui , Tüysüz Harun 
Published: May 2014

AbstractA systematic study on the growth of Cr2O3 in three‐dimensional cubic ordered mesoporous silica (KIT‐6) and its replication through nanocasting is reported. By changing the loading time and amount of precursor, the size and shape of the obtained replica could be controlled to some extent. More interestingly, in contrast to previously published studies, when KIT‐6 with an aging temperature of 100 °C, which has a high degree of interconnectivity, was used as a hard template, a cubic ordered mesoporous Cr2O3 replica with an open uncoupled subframework structure and reduced symmetry was obtained. Formation of a replica with different symmetry and uncoupled subframework structure is not only related to the degree of interconnectivity of the parent, but also strongly depends on the type of metal oxide and its growth mechanism in the silica template. Nanocasting of Cr2O3 with a low loading results in a replica with monomodal pore size distribution that has same symmetry as the hard template, whereas increasing the loading amount alters the symmetry of the replica and yields a replica with bimodal distribution.