bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triggering and modulation of geyser eruptions in Yellowstone National Park by earthquakes, earth tides, and weather
Authors: Hurwitz Shaul , Sohn Robert A. , Luttrell Karen , Manga Michael 
Published: February 2014

AbstractWe analyze intervals between eruptions (IBEs) data acquired between 2001 and 2011 at Daisy and Old Faithful geysers in Yellowstone National Park. We focus our statistical analysis on the response of these geysers to stress perturbations from within the solid earth (earthquakes and earth tides) and from weather (air pressure and temperature, precipitation, and wind). We conclude that (1) the IBEs of these geysers are insensitive to periodic stresses induced by solid earth tides and barometric pressure variations; (2) Daisy (pool geyser) IBEs lengthen by evaporation and heat loss in response to large wind storms and cold air; and (3) Old Faithful (cone geyser) IBEs are not modulated by air temperature and pressure variations, wind, and precipitation, suggesting that the subsurface water column is decoupled from the atmosphere. Dynamic stress changes of 0.1−0.2 MPa resulting from the 2002 M‐7.9 Denali, Alaska, earthquake surface waves caused a statistically significant shortening of Daisy geyser's IBEs. Stresses induced by other large global earthquakes during the study period were at least an order of magnitude smaller. In contrast, dynamic stresses of >0.5 MPa from three large regional earthquakes in 1959, 1975, and 1983 caused lengthening of Old Faithful's IBEs. We infer that most subannual geyser IBE variability is dominated by internal processes and interaction with other geysers. The results of this study provide quantitative bounds on the sensitivity of hydrothermal systems to external stress perturbations and have implications for studying the triggering and modulation of volcanic eruptions by external forces.
Deep‐water dynamics and boundary mixing in a nontidal stratified basin: A modeling study of the Baltic Sea
Authors: Holtermann Peter L. , Burchard Hans , Gräwe Ulf , Klingbeil Knut , Umlauf Lars 
Published: February 2014

AbstractRecent results from a tracer release experiment have shown that, similar to many lakes and ocean basins, deep‐water mixing in the Baltic Sea is largely determined by mixing processes occurring in the energetic near‐bottom region. Due to the complexity and small vertical extent of this region, however, previous modeling studies of the Baltic Sea have so far not been able to provide a numerically and physically sound representation of boundary mixing. Here we discuss first results from a nested high‐resolution simulation of the central Baltic Sea that aims at a realistic description of the turbulent bottom boundary layer with the help of new numerical techniques (adaptive coordinates) and state‐of‐the‐art turbulence modeling. Using a comprehensive data set from the Baltic Sea Tracer Release Experiment, we show that the model is able to reproduce the key dynamical processes (near‐inertial waves, topographic waves, and a rim current) with excellent accuracy. Boundary mixing triggered by these processes was found to result in simulated basin‐scale mixing rates in close agreement with observations, including a seasonal variability that has been emphasized in previous studies. These results may be relevant also for the description of mixing in large lakes and other stratified basins.
Wave‐induced light field fluctuations in measured irradiance depth profiles: A wavelet analysis
Authors: Wei Jianwei , Lewis Marlon R. , Van Dommelen Ronnie , Zappa Christopher J. , Twardowski Michael S. 
Published: February 2014

AbstractRapid variations in the intensities of light are commonly observed in profiles of downwelling plane irradiance in the ocean. These fluctuations are often treated as noise and filtered out. Here an effort is made to extract the pertinent statistics to quantify the light field fluctuations from vertical profiles of irradiance measured under clear skies. The irradiance data are collected in oceanic and coastal waters using a traditional free‐fall downwelling plane irradiance sensor. The irradiance profiles are transformed into time‐frequency domain with a wavelet technique. Two signatures including the dominant frequency (<3.5 Hz) and the coefficient of variation of irradiance fluctuations along the water column are identified from the variance spectrum. Both the dominant frequency and the amplitude decrease as the inverse square root of depth, consistent with simple models of wave focusing and data from other studies. Mechanisms contributing to the observed variations and the observational uncertainties are discussed.
Global inventory and characterization of pyroclastic deposits on Mercury: New insights into pyroclastic activity from MESSENGER orbital data
Authors: Goudge Timothy A. , Head James W. , Kerber Laura , Blewett David T. , Denevi Brett W. , Domingue Deborah L. , Gillis‐Davis Jeffrey J. , Gwinner Klaus , Helbert Jörn , Holsclaw Gregory M. , Izenberg Noam R. , Klima Rachel L. , McClintock William E. , Murchie Scott L. , Neumann Gregory A. , Smith David E. , Strom Robert G. , Xiao Zhiyong , Zuber Maria T. , Solomon Sean C. 
Published: February 2014

AbstractWe present new observations of pyroclastic deposits on the surface of Mercury from data acquired during the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. The global analysis of pyroclastic deposits brings the total number of such identified features from 40 to 51. Some 90% of pyroclastic deposits are found within impact craters. The locations of most pyroclastic deposits appear to be unrelated to regional smooth plains deposits, except some deposits cluster around the margins of smooth plains, similar to the relation between many lunar pyroclastic deposits and lunar maria. A survey of the degradation state of the impact craters that host pyroclastic deposits suggests that pyroclastic activity occurred on Mercury over a prolonged interval. Measurements of surface reflectance by MESSENGER indicate that the pyroclastic deposits are spectrally distinct from their surrounding terrain, with higher reflectance values, redder (i.e., steeper) spectral slopes, and a downturn at wavelengths shorter than ~400 nm (i.e., in the near‐ultraviolet region of the spectrum). Three possible causes for these distinctive characteristics include differences in transition metal content, physical properties (e.g., grain size), or degree of space weathering from average surface material on Mercury. The strength of the near‐ultraviolet downturn varies among spectra of pyroclastic deposits and is correlated with reflectance at visible wavelengths. We suggest that this interdeposit variability in reflectance spectra is the result of either variable amounts of mixing of the pyroclastic deposits with underlying material or inherent differences in chemical and physical properties among pyroclastic deposits.
The atypical generation mechanism of Titan's Schumann resonance
Authors: Béghin Christian 
Published: February 2014

AbstractThe observation of a presumed Schumann resonance (SR) during the landing of the Huygens Probe in Titan's atmosphere on January 2005 was subsequently reported and interpreted by Béghin et al. (2007, 2009, 2010, 2012) as being generated through the interaction of Saturn's magnetosphere with Titan's ionosphere rather than from the lightning activity that prevails on Earth. Beyond this atypical behavior, the existence of a single mode instead of the usual multimodal structure of terrestrial SRs and a comprehensive analysis of the physical generation mechanism remained to be investigated. The purpose of the present work is to draw up the baselines of a global model reconciling the Huygens data and the proposed generation mechanism. Based upon relevant observations obtained after several tenths of Titan's flybys by the Cassini orbiter, the modeling involves macro plasma physics processes as well as a global analysis of the mechanisms at the moon's scale. The clue to the SR's generation mechanism is shown to be the low‐frequency modulation of the Pedersen current sheets that are induced in the ionopause region by the corotating Saturn's magnetosphere. The modulation principle involves a wave coupling between the ion‐acoustic instabilities driven by the longitudinal current sheets and the electromagnetic quasi‐transverse whistler mode. The spectral distribution of the sole second eigenmode seen by the Huygens Probe is found to comply with the ionopause plasma parameters measured by Cassini during the bipolar configuration of Titan‐Saturn interaction that is thought to have occurred during the probe descent in the atmosphere.
The Atlantic Multidecadal Oscillation as a dominant factor of oceanic influence on climate
Authors: Chylek Petr , Klett James D. , Lesins Glen , Dubey Manvendra K. , Hengartner Nicolas 
Published: February 2014

AbstractA multiple linear regression analysis of global annual mean near‐surface air temperature (1900–2012) using the known radiative forcing and the El Niño–Southern Oscillation index as explanatory variables account for 89% of the observed temperature variance. When the Atlantic Multidecadal Oscillation (AMO) index is added to the set of explanatory variables, the fraction of accounted for temperature variance increases to 94%. The anthropogenic effects account for about two thirds of the post‐1975 global warming with one third being due to the positive phase of the AMO. In comparison, the Coupled Models Intercomparison Project Phase 5 (CMIP5) ensemble mean accounts for 87% of the observed global mean temperature variance. Some of the CMIP5 models mimic the AMO‐like oscillation by a strong aerosol effect. These models simulate the twentieth century AMO‐like cycle with correct timing in each individual simulation. An inverse structural analysis suggests that these models generally overestimate the greenhouse gases‐induced warming, which is then compensated by an overestimate of anthropogenic aerosol cooling.
Thermal Management Material: Graphite
Authors: Inagaki Michio , Kaburagi Yutaka , Hishiyama Yoshihiro 
Published: February 2014

AbstractGraphite has pronounced anisotropy in its properties. Thermal conductivity of graphite crystal is extremely high along its layer plane, as high as 2000 Wm−1 K−1, much higher than metals, and very low across its layer plane, as low as 7 Wm−1 K−1. This anisotropy gives high possibility for graphite as thermal management materials. Here, graphite membranes with high thermal conductivity along the surface for heat dissipation and with low conductivity perpendicular to the surface for heat insulation, in addition to graphite foams as container of phase change materials for heat energy storage, are reviewed, particularly referring to the preparations of various graphite materials. Thermal conductivity of diamond crystal is also high, 2500 Wm−1 K−1, but it is very sensitive for structural defects, but that of graphitic materials is less sensitive for structural defects, suggesting that the latter is more practical for thermal management than the former.
Anomalous Behavior of Load‐Dependent Friction on Ultra‐Nanocrystalline Diamond Film
Authors: Radhika Ramadoss , Kumar Niranjan , Dash Sitaram , Tyagi Ashok K. , Lin I‐Nan 
Published: February 2014

AbstractLoad dependent anomalous behavior of friction coefficient in ultra‐nanocrystalline diamond (UNCD) film was investigated while sliding against SiC ball. At low and high loads, the friction coefficient was quite high. However, at intermediate loads, ultra‐ low friction coefficient 0.002 was measured. Raman analysis of sliding interfaces showed evolution of high fraction of a‐C/sp2CC bonding at low and high loads. This invariably results in occurrences of unsaturated carbon atoms which chemically forms strong bonding. However, wear rate does not follow the trend of friction coefficient and found to increase with load. Such a behavior indicates that friction coefficient depends on the nature of chemical bonding present at sliding interfaces.
Synthesis, Structure, and Spectral and Electrochemical Properties of Meso‐Tetraaryl‐27‐Thiasapphyrins
Authors: Ganapathi Emandi , Lee Way‐Zen , Ravikanth Mangalampalli 
Published: February 2014

AbstractAn alternate synthetic route was developed for tetraaryl 27‐thiasapphyrins by condensation of meso‐aryl dipyrromethanes with 2,5‐bis(p‐tolylhydroxymethyl)thiophene under acid‐catalyzed conditions. Previously, 27‐thiasapphyrins have been prepared by a multistep synthesis using 2,2′‐bipyrrole as the key precursor. In our strategy, the pyrrole–pyrrole bond was generated to form 27‐thiasapphyrins by oxidative coupling of meso‐aryl dipyrromethane and 2,5‐bis(p‐tolylhydroxymethyl)thiophene, and the desired 27‐thiasapphyrins were isolated in 8–12 % yields. The crystal structure of one of the 27‐thiasapphyrins indicates that the macrocycle is almost planar and the thiophene sulfur atom is in the plane whereas the four pyrrole nitrogen atoms slightly deviate from the plane defined by four meso carbon atoms. Absorption spectroscopy showed four well defined Q bands in 590–770 nm and one strong Soret band in 470–480 nm region for 27‐thiasapphyrins. The 27‐thiasapphyrins are stable under redox conditions and undergo two‐to‐three reversible oxidations and one‐to‐two reversible reductions. The macrocycles are weakly fluorescent with low quantum yields and singlet state lifetimes.
Bioarchaeological investigation of ancient Maya violence and warfare in inland northwest Yucatan, Mexico
Authors: Serafin Stanley , Lope Carlos Peraza , Uc González Eunice 
Published: February 2014

ABSTRACTThis study investigates evidence of changes and continuities in ancient Maya violence and warfare in inland northwest Yucatan, Mexico from the Middle Preclassic (600–300 BC) to the Postclassic (AD 1050–1542) through bioarchaeological analysis of cranial and projectile trauma. It is hypothesized that the frequency of violence increases before the Classic Maya collapse and remains high during the Postclassic period. It is also hypothesized that the flat, open terrain was conducive to warfare and resulted in higher trauma frequencies than in other parts of the Maya area. Results show that the frequency of cranial trauma decreases before the Classic collapse and increases in the Postclassic, partially matching the expected chronological trends. The frequency of cranial trauma does not differ significantly from other Maya regions but the pattern does: for all periods, males have more healed injuries than females and they are concentrated on the left side of the anterior of the skull. Some injuries appear to be from small points hafted in wooden clubs. In addition, projectile trauma is evident in a scapula with an embedded arrowhead tip, the first such case reported in a Maya skeleton. Overall, these results suggest greater reliance on open combat and less on raids in this region compared with other parts of the Maya area, possibly due to the flat, open terrain, though the identification of perimortem trauma in both women and men indicates surprise raids on settlements were also practiced. Am J Phys Anthropol 154:140–151, 2014. © 2014 Wiley Periodicals, Inc.
Bis hin zu einer Symphonie der Reaktivität: Kaskaden mit Katalysen und sigmatropen Umlagerungen
Authors: Jones Amanda C. , May Jeremy A. , Sarpong Richmond , Stoltz Brian M. 
Published: February 2014

AbstractDie Katalyse und die Synthese sind in der modernen organischen Chemie eng miteinander verbunden. Die Synthese komplexer Moleküle ist ein sich ständig weiterentwickelndes Gebiet. In vielerlei Hinsicht kann die inhärente Schönheit einer Synthesesequenz mit einer bestimmten Kombination aus Kreativität, mit der eine Sequenz entworfen wurde, und der Gesamteffizienz, mit der das endgültige Verfahren durchgeführt wird, in Zusammenhang gebracht werden. Ebenso wie bei anderen Unterfangen liegt bei chemischen Synthesen die Schönheit im Auge des Betrachters. In diesem Sinne werden wir versuchen, ein Gebiet der Synthese zu erörtern, das uns fasziniert, und das wir außergewöhnlich schön finden, nämlich die Kombination aus Katalyse und sigmatropen Umlagerungen in konsekutiven Sequenzen und Kaskadenreaktionen.
Manchmal erfolgt die Einschätzung von Schönheit nahezu einstimmig. Bei den ersten vier Noten von Beethovens 5. Symphonie (Symphonie Nr.5 in c‐Moll, op.67) handelt es sich vielleicht um das bekannteste und beliebteste Motiv in der klassischen Musik. Die Orchesterpartitur ist im Hintergrund des Titelbildes abgebildet. http://imslp.org/wiki/Symphony_No.5,_Op.67_%28Beethoven,_Ludwig_van%29, abgerufen am 20. März 2013.
N‐terminale Proteinmodifizierung mittels Substrat‐aktivierter Katalyse
Authors: Liebscher Sandra , Schöpfel Michael , Aumüller Tobias , Sharkhuukhen Ariunkhur , Pech Andreas , Höss Eva , Parthier Christoph , Jahreis Günther , Stubbs Milton T. , Bordusa Frank 
Published: February 2014

AbstractArtifizielle Funktionalisierungen von Proteinen stellen sowohl in der angewandten als auch in der Grundlagenforschung ein wichtiges Werkzeug dar und erweisen sich als eine Herausforderung für Proteinchemiker. Aufgrund ihrer nativen Regio‐ und Stereoselektivität bieten enzymatische Proteinmodifizierungen einen attraktiven Ansatz, jedoch ist eine universelle Anwendung durch deren hohe Spezifität beschränkt. Aufgrund der intrinsischen Reversibilität enzymatischer Reaktionen sind Proteinasen prinzipiell in der Lage auch Ligationen zu katalysieren. Dies macht sie zu einem interessanten Werkzeug für spezifische Proteinkonjugationen. Wir berichten über die Entwicklung einer hochspezifischen Trypsinvariante für die selektive N‐terminale Modifizierung von Proteinen. Die Reaktion verläuft mit quantitativen Produktausbeuten unter nativen Bedingungen. Wir zeigen, dass die Variante eine ungeordnete Zymogen‐ähnliche Aktivierungsdomäne aufweist, die in Gegenwart geeigneter Substrate in die aktive Konformation überführt wird.
Perowskit als Lichtabsorptionsmaterial: ein Durchbruch in der Photovoltaik
Authors: Kazim Samrana , Nazeeruddin Mohammad Khaja , Grätzel Michael , Ahmad Shahzada 
Published: February 2014

AbstractEs geschieht nicht oft, dass die Forschung auf ein Material stößt, das zu größten Hoffnungen Anlass gibt und von verschiedenster Seite Interesse erfährt. Wenn es geschieht, verläuft die Entwicklung rasant. Ein solches Material ist Perowskit, das gänzlich neue Konzepte in der Energieumwandlung angestoßen hat. Perowskite sind aufgrund ihrer panchromatischen Lichtabsorption und ihrem ambipolaren Verhalten von herausragendem Interesse als Material für die Photovoltaik. Der maximale Wirkungsgrad von Perowskit‐Solarzellen hat sich in weniger als einem Jahr verdoppelt und erreicht nun Werte von 15 % unter Laborbedingungen. Dies ist besonders markant in einem wissenschaftlichen und industriellen Umfeld, in dem jede Steigerung in der Nachkommastelle als Erfolg gefeiert und breit diskutiert wird. Wir fassen hier den Stand der Forschung bei der Verwendung von Perowskitmaterialien für Solarzellen zusammen.
Electrochemically Assisted Generation of Highly Ordered Azide‐Functionalized Mesoporous Silica for Oriented Hybrid Films
Authors: Vilà Neus , Ghanbaja Jaafar , Aubert Emmanuel , Walcarius Alain 
Published: February 2014

AbstractOne key challenge in inorganic mesoporous films is the development of oriented mesostructures with vertical channels, and even more challenging is their functionalization while maintaining accessible the selected surface groups. Combining the electrochemically assisted deposition of ordered and oriented azide‐functionalized mesoporous silica with alkyne–azide click chemistry enables such nanostructured and vertically aligned hybrid films to be obtained with significant amounts of active organic functional groups, as illustrated for ferrocene and pyridine functions. A good level of mesostructural order was obtained, namely up to 40 % of organosilane in the starting sol. The method could be applied to a wide variety of functional groups, thus offering numerous new opportunities for applications in various fields.
Copolymerization of Metal Nanoparticles: A Route to Colloidal Plasmonic Copolymers
Authors: Liu Kun , Lukach Ariella , Sugikawa Kouta , Chung Siyon , Vickery Jemma , Therien‐Aubin Heloise , Yang Bai , Rubinstein Michael , Kumacheva Eugenia 
Published: February 2014

AbstractThe resemblance between colloidal and molecular polymerization reactions is very useful in fundamental studies of polymerization reactions, as well as in the development of new nanoscale systems with desired properties. Future applications of colloidal polymers will require nanoparticle ensembles with a high degree of complexity that can be realized by hetero‐assembly of NPs with different dimensions, shapes, and compositions. A method has been developed to apply strategies from molecular copolymerization to the co‐assembly of gold nanorods with different dimensions into random and block copolymer structures (plasmonic copolymers). The approach was extended to the co‐assembly of random copolymers of gold and palladium nanorods. A kinetic model validated and further expanded the kinetic theories developed for molecular copolymerization reactions.
Elevated Catalytic Activity of Ruthenium(II)–Porphyrin‐Catalyzed Carbene/Nitrene Transfer and Insertion Reactions with N‐Heterocyclic Carbene Ligands
Authors: Chan Ka‐Ho , Guan Xiangguo , Lo Vanessa Kar‐Yan , Che Chi‐Ming 
Published: February 2014

AbstractBis(NHC)ruthenium(II)–porphyrin complexes were designed, synthesized, and characterized. Owing to the strong donor strength of axial NHC ligands in stabilizing the trans MCRR′/MNR moiety, these complexes showed unprecedently high catalytic activity towards alkene cyclopropanation, carbene CH, NH, SH, and OH insertion, alkene aziridination, and nitrene CH insertion with turnover frequencies up to 1950 min−1. The use of chiral [Ru(D4‐Por)(BIMe)2] (1 g) as a catalyst led to highly enantioselective carbene/nitrene transfer and insertion reactions with up to 98 % ee. Carbene modification of the N terminus of peptides at 37 °C was possible. DFT calculations revealed that the trans axial NHC ligand facilitates the decomposition of diazo compounds by stabilizing the metal–carbene reaction intermediate.
Rapid Generation of Cell Gradients by Utilizing Solely Nanotopographic Interactions on a Bio‐Inert Glass Surface
Authors: Yang Gao , Cao Yanhua , Fan Junbing , Liu Hongliang , Zhang Feilong , Zhang Pengchao , Huang Chao , Jiang Lei , Wang Shutao 
Published: February 2014

AbstractThe control of cell gradients is critical for understanding many biological systems and realizing the unique functionality of biomimetic implants. Herein, we report a nanotopographic gradient strategy that can rapidly generate cell gradients on a nanodendritic silica substrate without any chemical modification. We can achieve controllable cell gradients within only half an hour of cell incubation solely induced by the topographic effect of the gradient nanodendrites. We also demonstrate that cell gradients can be modulated by the combination of nanotopographic and chemical gradients. The results reveal that the enhanced topographic interactions between the nanodentritic structure and nanoscaled filopodia of the cells mainly contribute to the generation of cell gradients.