bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ash mists and brown snow: Remobilization of volcanic ash from recent Icelandic eruptions
Authors: Liu E. J. , Cashman K. V. , Beckett F. M. , Witham C. S. , Leadbetter S. J. , Hort M. C. , Guðmundsson S. 
Published: July 2014

AbstractRecent eruptions in Iceland and Chile have demonstrated that volcanic ash problems persist long after an eruption. For this reason, ash dispersion models are being extended to include ash remobilization. Critical to these models is knowledge of the ash source and the particle sizes that can be mobilized under different wind and moisture conditions. Here we characterize the physical and chemical characteristics of ash deposited on new snow in Reykjavík, Iceland, following a blizzard on 6 March 2013. Morphological, textural, and compositional analyses indicate resuspension from multiple eruptive deposits, including both Grímsvötn (2011) and Eyjafjallajökull (2010) eruptions. Grain size measurements show a mode of 32–63 µm, with particles as large as 177 µm; there is little mass in the very fine fraction, ≤10 µm (PM10). We compare our observations to predictions using the Lagrangian particle dispersion model, NAME (UK Met Office). The model output is consistent with observations in that it forecasts resuspension from both Eyjafjallajökull and Grímsvötn source regions, and shows ash deposition coincident with the timing of observed deposition in Reykjavík. The modeled deposit in Reykjavík predicts, however, a substantially lower proportion of Grímsvötn ash than observed. This discrepancy has highlighted the need to reassess the assumptions used in the simulations, particularly regarding the source area and precipitation thresholds. Furthermore, we suggest that modification of ash deposits in the form of erosion, redeposition, compaction, or cementation may influence the dynamics of resuspension over time, thus influencing the ability of model simulations to accurately forecast remobilization events.
A quick gap filling of missing hydrometeorological data
Authors: Pappas Christoforos , Papalexiou Simon Michael , Koutsoyiannis Demetris 
Published: July 2014

AbstractData gaps are ubiquitous in hydrometeorological time series, and filling these values still remains a challenge. Since data sets without missing values may be a prerequisite in performing many analyses, a quick and efficient gap‐filling methodology is required. In this study the problem of filling sporadic, single‐value gaps using time‐adjacent observations from the same location is investigated. The applicability of a local average (i.e., based on few neighboring in time observations) is examined and its advantages over the sample average (i.e., using the whole data set) are illustrated. The analysis reveals that a quick and very efficient (i.e., minimum mean‐squared estimation error) gap filling is achieved by combining a strictly local average (i.e., using one observation before and one after the missing value) with the sample mean.
The QBO in two GISS global climate models: 1. Generation of the QBO
Authors: Rind D. , Jonas J. , Balachandran N. K. , Schmidt G. A. , Lean J. 
Published: July 2014

AbstractThe adjustment of parameterized gravity waves associated with model convection and finer vertical resolution has made possible the generation of the quasi‐biennial oscillation (QBO) in two Goddard Institute for Space Studies (GISS) models, GISS Middle Atmosphere Global Climate Model III and a climate/middle atmosphere version of Model E2. Both extend from the surface to 0.002 hPa, with 2° × 2.5° resolution and 102 layers. Many realistic features of the QBO are simulated, including magnitude and variability of its period and amplitude. The period itself is affected by the magnitude of parameterized convective gravity wave momentum fluxes and interactive ozone (which also affects the QBO amplitude and variability), among other forcings. Although varying sea surface temperatures affect the parameterized momentum fluxes, neither aspect is responsible for the modeled variation in QBO period. Both the parameterized and resolved waves act to produce the respective easterly and westerly wind descent, although their effect is offset in altitude at each level. The modeled and observed QBO influences on tracers in the stratosphere, such as ozone, methane, and water vapor are also discussed. Due to the link between the gravity wave parameterization and the models' convection, and the dependence on the ozone field, the models may also be used to investigate how the QBO may vary with climate change.
Downscaling with a nested regional climate model in near‐surface fields over the contiguous United States
Authors: Wang Jiali , Kotamarthi Veerabhadra R. 
Published: July 2014

AbstractThe Weather Research and Forecasting (WRF) model is used for dynamic downscaling of 2.5‐degree National Centers for Environmental Prediction‐U.S. Department of Energy Reanalysis II (NCEP‐R2) data for 1980–2010 at 12 km resolution over most of North America. The model's performance for surface air temperature and precipitation is evaluated by comparison with high‐resolution observational data sets. The model's ability to add value is investigated by comparison with NCEP‐R2 data and a 50 km regional climate simulation. The causes for major model bias are studied through additional sensitivity experiments with various model setup/integration approaches and physics representations. The WRF captures the main features of the spatial patterns and annual cycles of air temperature and precipitation over most of the contiguous United States. However, simulated air temperatures over the south central region and precipitation over the Great Plains and the Southwest have significant biases. Allowing longer spin‐up time, reducing the nudging strength, or replacing the WRF Single‐Moment six‐class microphysics with Morrison microphysics reduces the bias over some subregions. However, replacing the Grell‐Devenyi cumulus parameterization with Kain‐Fritsch shows no improvement. The 12 km simulation does add value above the NCEP‐R2 data and the 50 km simulation over mountainous and coastal zones.
The life cycle of instability features measured from the Andes Lidar Observatory over Cerro Pachon on 24 March 2012
Authors: Hecht J. H. , Wan K. , Gelinas L. J. , Fritts D. C. , Walterscheid R. L. , Rudy R. J. , Liu A. Z. , Franke S. J. , Vargas F. A. , Pautet P. D. , Taylor M. J. , Swenson G. R. 
Published: July 2014

AbstractThe Aerospace Corporation's Nightglow Imager (ANI) observes nighttime OH emission (near 1.6 μm) every 2 s over an approximate 73° field of view. ANI had previously been used to study instability features seen over Maui. Here we describe observations of instabilities seen from 5 to 8 UT on 24 March 2012 over Cerro Pachon, Chile, and compare them with previous results from Maui, with theory, and with Direct Numerical Simulations (DNS). The atmosphere had reduced stability because of the large negative temperature gradients measured by a Na lidar. Thus, regions of dynamical and convective instabilities are expected to form, depending on the value of the Richardson number. Bright primary instabilities are formed with a horizontal wavelength near 9 km and showed the subsequent formation of secondary instabilities, rarely seen over Maui, consistent with the primaries being dynamical instabilities. The ratio of the primary to secondary horizontal wavelength was greater over Chile than over Maui. After dissipation of the instabilities, smaller‐scale features appeared with sizes in the buoyancy subrange between 1.5 and 6 km. Their size spectra were consistent with the model of Weinstock (1978) if the turbulence is considered to be increasing. The DNS results produce secondary instabilities with sizes comparable to what is seen in the images although their spectra are somewhat steeper than is observed. However, the DNS results also show that after the complete decay of the primary features, scale sizes considerably smaller than 1 km are produced and these cannot be seen by the ANI instrument.
Prenatal diagnosis of CLOVES syndrome confirmed by detection of a mosaic PIK3CA mutation in cultured amniocytes
Authors: Emrick Lisa T. , Murphy Lauren , Shamshirsaz Alireza A. , Ruano Rodrigo , Cassady Christopher I. , Liu Liu , Chang Fengqi , Sutton V. Reid , Li Marilyn , Van den Veyver Ignatia B. 
Published: July 2014

ABSTRACTCongenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined‐type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome, a segmental overgrowth syndrome, is caused by post zygotic somatic mutations in PIK3CA, a gene involved in the receptor tyrosine kinase phosphatidylinositol 3‐kinase (PI3)‐AKT growth‐signaling pathway. Prenatal ultrasound findings of lymphovascular malformations, segmental overgrowth and skeletal defects can raise suspicion for CLOVES syndrome, but molecular confirmation of PIK3CA mutations on prenatally obtained samples is challenging because of somatic mosaicism. We detected a mosaic disease‐causing mutation in PIK3CA by sequencing of DNA extracted from cultured amniotic cells, but not from DNA directly prepared from an amniotic fluid sample in a fetus with prenatally suspected CLOVES syndrome. The infant was born prematurely and displayed severe lymphovascular malformations and segmental overgrowth consistent with a clinical diagnosis of CLOVES syndrome; he passed away at 29 days of life. We discuss the complexities and limitations of genetic testing for somatic mosaic mutations in the prenatal period and highlight the potential need for multiple approaches to arrive at a molecular diagnosis. © 2014 Wiley Periodicals, Inc.
A Ruthenium‐Based Light‐Harvesting Antenna Bearing an Anthracene Moiety in Dye‐Sensitized Solar Cells
Authors: Vougioukalakis Georgios C. , Konstantakou Maria , Pefkianakis Eleftherios K. , Kabanakis Antonios N. , Stergiopoulos Thomas , Kontos Athanassios G. , Andreopoulou Aikaterini K. , Kallitsis Joannis K. , Falaras Polycarpos 
Published: July 2014

AbstractA heteroleptic ruthenium sensitizer (DV56) bearing a terpyridine ligand with an appended phenylanthracene moiety was synthesized and extensively characterized. The physicochemical properties of the light‐harvesting antenna were studied in solution and on sensitized TiO2 thin film electrodes using a variety of spectroscopic and photoelectrochemical techniques. Contact angle measurements suggest that the DV56‐sensitized TiO2 films are hydrophilic. Raman measurements indicate chemisorption of the dye on the semiconducting surface. Electrochemical studies of the dye show that its first oxidation potential lies well below the I−/I3− redox potential, allowing easy regeneration. Moreover, its excited state oxidation potential lies above the TiO2 conduction band edge, permitting efficient electron injection from the photosensitizer into the semiconductor. I−/I3−‐based liquid redox electrolyte dye‐sensitized solar cells incorporating DV56‐sensitized TiO2 photoelectrodes afford an overall power conversion efficiency of 3.75 %.
Relationship between systolic blood pressures measured in emergency department and outcomes in patients with subarachnoid hemorrhage
Authors: Inamasu Joji , Oheda Motoki , Ito Keisuke , Kato Yoko , Hirose Yuichi 
Published: July 2014

AimHigh blood pressure is observed frequently in patients with subarachnoid hemorrhage who present to the emergency department. Although extremely high blood pressure is known to predict poor outcomes in patients with spontaneous intracerebral hemorrhage, the relationship between high blood pressure and outcomes has been studied less frequently in patients with subarachnoid hemorrhage.MethodsA retrospective study was carried out to evaluate whether high blood pressure observed in the emergency department was predictive of poor outcomes in patients with subarachnoid hemorrhage. Three‐hundred and twelve subarachnoid hemorrhage patients who were admitted to our institution were quadrichotomized based on their initial systolic blood pressure: <140 mmHg (n = 60), 140–184 mmHg (n = 144), 185–219 mmHg (n = 64), and ≥220 mmHg (n = 44). Demographics including subarachnoid hemorrhage severity (World Federation of Neurosurgical Societies grade) and outcome variables evaluated with the modified Rankin scale 30 days after admission were compared among the four blood pressure groups. Furthermore, an effort was made to delineate a threshold value of systolic blood pressure predictive of outcomes by receiver operating characteristic curve analysis.ResultsThe frequency of grade V subarachnoid hemorrhage in the ≥220 mmHg group (55%) was significantly higher than in the other three blood pressure groups. The frequency of patients scoring 5–6 on the modified Rankin scale in the ≥220 mmHg group (54%) was significantly higher than in the other three blood pressure groups. The cut‐off systolic blood pressure value predicting poor outcomes (modified Rankin scale 5–6) determined by receiver operating characteristic curve analysis was 189 mmHg.ConclusionsThe higher proportion of grade V patients may be responsible for the worse outcomes in the group with systolic blood pressure ≥220 mmHg. Initial systolic blood pressure ≥220 mmHg may be a crude indicator of poor outcomes in patients with subarachnoid hemorrhage.
Wechselwirkungen von Proteinen mit Polymerbeschichtungen und Biomaterialien
Authors: Wei Qiang , Becherer Tobias , Angioletti‐Uberti Stefano , Dzubiella Joachim , Wischke Christian , Neffe Axel T. , Lendlein Andreas , Ballauff Matthias , Haag Rainer 
Published: July 2014

AbstractDie Proteinadsorption gilt als der wichtigste Faktor der Wechselwirkung zwischen polymeren Biomaterialien und Körperflüssigkeiten oder ‐gewebe. Die Haupteinflussfaktoren auf die Proteinadsorption sind wasservermittelte hydrophobe und Hydratationskräfte sowie elektrostatische Wechselwirkungen. Eine systematische Analyse verschiedener Monolagen führte zur Aufstellung allgemeiner Leitsätze, den sogenannten “Whitesides‐Regeln”. Diese Konzepte wurden erfolgreich auf die Entwicklung verschiedener proteinresistenter Oberflächen angewendet und werden kontinuierlich weiterentwickelt, um das Verständnis von Protein‐Material‐Wechselwirkungen über die bisherigen Grenzen hinaus zu erweitern. Ebenso werden die Theorien zu Proteinadsorptionsmechanismen aufgrund der sich schnell entwickelnden analytischen Technologien fortlaufend verbessert. Ziel dieses Aufsatzes ist die Verbesserung der aufgestellten empirischen Leitlinien im Hinblick auf die theoretischen und analytischen Fortschritte. Dabei werden die aktuellen analytischen Methoden zur Untersuchung mechanistischer Hypothesen und Theorien zu Protein‐Oberflächen‐Wechselwirkungen besprochen. Ein besonderes Augenmerk liegt auf aktuellen Technologien im Bereich bioinerter und biospezifischer Beschichtungen und ihrer Anwendungen in der Biomedizin.
Harnessing the Liquid‐Phase Exfoliation of Graphene Using Aliphatic Compounds: A Supramolecular Approach
Authors: Ciesielski Artur , Haar Sébastien , El Gemayel Mirella , Yang Huafeng , Clough Joseph , Melinte Georgian , Gobbi Marco , Orgiu Emanuele , Nardi Marco V. , Ligorio Giovanni , Palermo Vincenzo , Koch Norbert , Ersen Ovidiu , Casiraghi Cinzia , Samorì Paolo 
Published: July 2014

AbstractThe technological exploitation of the extraordinary properties of graphene relies on the ability to achieve full control over the production of a high‐quality material and its processing by up‐scalable approaches in order to fabricate large‐area films with single‐layer or a few atomic‐layer thickness, which might be integrated in working devices. A simple method is reported for producing homogenous dispersions of unfunctionalized and non‐oxidized graphene nanosheets in N‐methyl‐2‐pyrrolidone (NMP) by using simple molecular modules, which act as dispersion‐stabilizing compounds during the liquid‐phase exfoliation (LPE) process, leading to an increase in the concentration of graphene in dispersions. The LPE‐processed graphene dispersion was shown to be a conductive ink. This approach opens up new avenues for the technological applications of this graphene ink as low‐cost electrodes and conducting nanocomposite for electronics.
Funktionalisiertes Graphen als Türsteher für chirale Moleküle: ein alternatives Konzept zur Racematspaltung
Authors: Hauser Andreas W. , Mardirossian Narbe , Panetier Julien A. , Head‐Gordon Martin , Bell Alexis T. , Schwerdtfeger Peter 
Published: July 2014

AbstractEin neuartiges, auf funktionalisiertem, nanoporösen Graphen basierendes Verfahren zur Abtrennung chiraler Moleküle wird vorgestellt. Auf Dichtefunktionaltheorie basierende Computersimulationen zeigen, dass durch Anhaften eines chiralen “Türsteher”‐Moleküls an den Porenrand einer Form des Enantiomers der Eintritt verweigert wird, während sein Spiegelbild passieren kann.
A Conical Intersection Controls the Deactivation of the Bacterial Luciferase Fluorophore
Authors: Gozem Samer , Mirzakulova Ekaterina , Schapiro Igor , Melaccio Federico , Glusac Ksenija D. , Olivucci Massimo 
Published: July 2014

AbstractThe photophysics of flavins is highly dependent on their environment. For example, 4a‐hydroxy flavins display weak fluorescence in solution, but exhibit strong fluorescence when bound to a protein. To understand this behavior, we performed temperature‐dependent fluorescent studies on an N(5)‐alkylated 4a‐hydroxy flavin: the putative bacterial luciferase fluorophore. We find an increase in fluorescence quantum yield upon reaching the glass transition temperature of the solvent. We then employ multiconfigurational quantum chemical methods to map the excited‐state deactivation path of the system. The result reveals a shallow but barrierless excited state deactivation path that leads to a conical intersection displaying an orthogonal out‐of‐plane distortion of the terminal pyrimidine ring. The intersection structure readily explains the observed spectroscopic behavior in terms of an excited‐state barrier imposed by the rigid glass cavity.
Tailoring Intermolecular Interactions for Efficient Room‐Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices
Authors: Kwon Min Sang , Lee Dongwook , Seo Sungbaek , Jung Jaehun , Kim Jinsang 
Published: July 2014

AbstractHerein we report a rational design strategy for tailoring intermolecular interactions to enhance room‐temperature phosphorescence from purely organic materials in amorphous matrices at ambient conditions. The built‐in strong halogen and hydrogen bonding between the newly developed phosphor G1 and the poly(vinyl alcohol) (PVA) matrix efficiently suppresses vibrational dissipation and thus enables bright room‐temperature phosphorescence (RTP) with quantum yields reaching 24 %. Furthermore, we found that modulation of the strength of halogen and hydrogen bonding in the G1–PVA system by water molecules produced unique reversible phosphorescence‐to‐fluorescence switching behavior. This unique system can be utilized as a ratiometric water sensor.
UV Excited‐State Photoresponse of Biochromophore Negative Ions
Authors: Bochenkova Anastasia V. , Klærke Benedikte , Rahbek Dennis B. , Rajput Jyoti , Toker Yoni , Andersen Lars H. 
Published: July 2014

AbstractMembers of the green fluorescent protein (GFP) family may undergo irreversible phototransformation upon irradiation with UV light. This provides clear evidence for the importance of the higher‐energy photophysics of the chromophore, which remains essentially unexplored. By using time‐resolved action and photoelectron spectroscopy together with high‐level electronic structure theory, we directly probe and identify higher electronically excited singlet states of the isolated para‐ and meta‐chromophore anions of GFP. These molecular resonances are found to serve as a doorway for very efficient electron detachment in the gas phase. Inside the protein, this band is found to be resonant with the quasicontinuum of a solvated electron, thus enhancing electron transfer from the GFP to the solvent. This suggests a photophysical pathway for photoconversion of the protein, where GFP resonant photooxidation in solution triggers radical redox reactions inside these proteins.
Self‐Healable Electrically Conducting Wires for Wearable Microelectronics
Authors: Sun Hao , You Xiao , Jiang Yishu , Guan Guozhen , Fang Xin , Deng Jue , Chen Peining , Luo Yongfeng , Peng Huisheng 
Published: July 2014

AbstractElectrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next‐generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high‐performance conducting wires that can self‐heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self‐healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self‐healable wire‐shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self‐healing.
Stereocontrolled Synthesis of 1,5‐Stereogenic Centers through Three‐Carbon Homologation of Boronic Esters
Authors: Unsworth Phillip J. , Leonori Daniele , Aggarwal Varinder K. 
Published: July 2014

AbstractAllylic pinacol boronic esters are stable toward 1,3‐borotropic rearrangement. We developed a PdII‐mediated isomerization process that gives di‐ or trisubstituted allylic boronic esters with high E selectivity. The combination of this method with lithiation–borylation enables the synthesis of carbon chains that bear 1,5‐stereogenic centers. The utility of this method has been demonstrated in a formal synthesis of (+)‐jasplakinolide.
Orientation‐Controlled Single‐Molecule Junctions
Authors: Afsari Sepideh , Li Zhihai , Borguet Eric 
Published: July 2014

AbstractThe conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM‐BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat‐oriented mesitylene molecules on Au(111) to enable direct tip/π contacts, a result that is not possible by conventional methods. The measured conductance of Au/π/Au junction is about 0.1 Go , two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long‐range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation‐controlled molecular junctions.
Ligand Modification Transforms a Catalase Mimic into a Water Oxidation Catalyst
Authors: Lee Wei‐Tsung , Muñoz Salvador B. , Dickie Diane A. , Smith Jeremy M. 
Published: July 2014

AbstractThe catalytic reactivity of the high‐spin MnII pyridinophane complexes [(Py2NR2)Mn(H2O)2]2+ (R=H, Me, tBu) toward O2 formation is reported. With small macrocycle N‐substituents (R=H, Me), the complexes catalytically disproportionate H2O2 in aqueous solution; with a bulky substituent (R=tBu), this catalytic reaction is shut down, but the complex becomes active for aqueous electrocatalytic H2O oxidation. Control experiments are in support of a homogeneous molecular catalyst and preliminary mechanistic studies suggest that the catalyst is mononuclear. This ligand‐controlled switch in catalytic reactivity has implications for the design of new manganese‐based water oxidation catalysts.