bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass transport waves amplified by intense Greenland melt and detected in solid Earth deformation
Authors: Adhikari S. , Ivins E. R. , Larour E. 
Published: May 2017

AbstractThe annual cycle and secular trend of Greenland mass loading are well recorded in measurements of solid Earth deformation. Horizontal crustal displacements can potentially track the spatiotemporal detail of mass changes with great fidelity. Our analysis of Greenland crustal motion data reveals that a significant excitation of horizontal amplitudes occurs during the intense melt years. We discover that solitary seasonal waves of substantial mass transport (1.67 ± 0.54 Gt/month) traveled at an average speed of 7.1 km/month through Rink Glacier in 2012. We deduce that intense surface melting enhanced either basal lubrication or softening of shear margins, or both, causing the glacier to thin dynamically in summer. The newly routed upstream subglacial water was likely to be both retarded and inefficient, thus providing a causal mechanism for the prolonged ice transport to continue well into the winter months. As the climate continues to produce increasingly warmer spring and summer, amplified seasonal waves of mass transport may become ever more present with important ramifications for the future sea level rise.
Hydroacoustic ray theory‐based modeling of T wave propagation in the deep ocean basin offshore eastern Taiwan
Authors: Chen Chin‐Wu , Huang Chen‐Fen , Lin Chien‐Wen , Kuo Ban‐Yuan 
Published: May 2017

AbstractT waves are conventionally defined as seismically generated acoustic energy propagating horizontally over long distances within the minimum sound speed layer in the ocean (SOFAR axis minimum). However, T waves have also been observed by ocean‐bottom seismometers in ocean basins at depths greater than the SOFAR axis minimum. Previously, nongeometrical processes, such as local scattering at rough seafloor and water‐sediment interface coupling, have been proposed as possible mechanisms for deep seafloor detection of T waves. Here we employ a new T wave modeling approach based on hydroacoustic ray theory to demonstrate that seismoacoustic energy can propagate to reach deep seafloor, previously considered as shadow zone of acoustic propagation. Our new hydroacoustic simulations explain well the observations of T waves on ocean‐bottom seismometers at deep ocean basins east of Taiwan and shed new light on the mechanism for deep ocean T wave propagation.
A new heat flux model for the Antarctic Peninsula incorporating spatially variable upper crustal radiogenic heat production
Authors: Burton‐Johnson A. , Halpin J. A. , Whittaker J. M. , Graham F. S. , Watson S. J. 
Published: May 2017

AbstractA new method for modeling heat flux shows that the upper crust contributes up to 70% of the Antarctic Peninsula's subglacial heat flux and that heat flux values are more variable at smaller spatial resolutions than geophysical methods can resolve. Results indicate a higher heat flux on the east and south of the Peninsula (mean 81 mW m−2) where silicic rocks predominate, than on the west and north (mean 67 mW m−2) where volcanic arc and quartzose sediments are dominant. While the data supports the contribution of heat‐producing element‐enriched granitic rocks to high heat flux values, sedimentary rocks can be of comparative importance dependent on their provenance and petrography. Models of subglacial heat flux must utilize a heterogeneous upper crust with variable radioactive heat production if they are to accurately predict basal conditions of the ice sheet. Our new methodology and data set facilitate improved numerical model simulations of ice sheet dynamics.
Intercomparison of radar meteor velocity corrections using different ionization coefficients
Authors: Williams E. R. , Wu Y.‐J. , Chau J. , Hsu R.‐R. 
Published: May 2017

AbstractSensitive long‐wavelength radar observations of absolute velocity never previously published from Jicamarca are brought to bear on the long‐standing problem of radar detection of slow‐moving meteors. Attention is devoted to evaluating the ionization coefficient β(V) in the critically important velocity range of 11–20 km/s in recent laboratory measurements of Thomas et al. (2016). Theoretical predictions for β(V) based on the laboratory data, on Jones (1997), on Janches et al. (2014), and on Verniani and Hawkins (1964) are used to correct the incoming meteor velocities measured with the sensitive Jicamarca high‐power, large‐aperture radar operating at 6 m wavelength. All corrected distributions are consistent with the predictions of the Nesvorný model in showing pronounced monotonic increases down to the escape velocity (11 km/s). Such distributions may be essential to explaining the pronounced ledge in nighttime electron density and the rapid disappearance of electrons in meteor trails in the altitude range of 80–85 km.
Calculating the inductive electric field in the terrestrial magnetosphere
Authors: Ilie Raluca , Daldorff Lars K. S. , Liemohn Michael W. , Toth Gabor , Chan Anthony A. 
Published: May 2017

AbstractThis study presents a theoretical approach to calculate the inductive electric field, and it is further applied to global MHD simulations of the magnetosphere. The contribution of the inductive component to the total electric field is found by decomposing the motional electric field into a superposition of an irrotational and a solenoidal vector and assuming that the time‐varying magnetic field vanishes on the boundary. We find that a localized change in the magnetic field generates an inductive electric field whose effect extends over all space, meaning that the effect of the inductive electric field is global even if the changes in the magnetic field are localized. Application of this formalism to disturbed times provides strong evidence that during periods of increased activity the electric field induced by the localized change in magnetic field can be comparable to (or larger than) the potential electric fields in certain regions. This induced field exhibits significant spatial and temporal variations, which means that particles that drift into different regions of space are being exposed to different means of acceleration. These results suggest that the inductive electric field could have a substantial contribution to particle energization in the near‐Earth region even though the changes in the magnetic fields occur at distances of several tens of Earth radii. This finding is particularly important for ring current modeling which in many cases excludes inductive contributions to the total particle drift.
Equatorial plasma bubbles: Variations of occurrence and spatial scale in local time, longitude, season, and solar activity
Authors: Smith Jonathon , Heelis Rod A. 
Published: May 2017

AbstractWe examine the location and structure of equatorial topside depletions referred to here as equatorial plasma bubbles (EPBs). The Coupled Ion Neutral Dynamics Investigation Ion Velocity Meter instrument on board the Communication/Navigation Outage Forecasting System is used to measure the ion density from August 2008 to December 2014, a time period in which solar activity transitioned from solar minimum conditions to more moderate solar activity conditions. EPB data are divided into four longitude sectors to determine seasonal and solar cycle variability. In the early phase of the mission, during solar minimum, EPBs occur late in local time, primarily after midnight in all longitude sectors. In the later phase of the mission EPB occurrence after midnight diminishes in all seasons and longitude sectors with the exception of the sector extending from −15° to 60°. An examination of the widths of bubbles indicates that all longitudes show similar distributions between 115 km and 460 km with a prominent peak near 200 km. Among these widths is a distinct width that belongs to discrete individual bubbles with no substructure. We suggest that many bubbles are actually combinations of these individual bubbles; however, in the later phase of the mission there is a population of bubbles that do not conform to this description, perhaps due to the influence of large‐scale plasma motions affecting the background density in which they are embedded.
On the sensitivity of anthropogenic aerosol forcing to model‐internal variability and parameterizing a Twomey effect
Authors: Fiedler S. , Stevens B. , Mauritsen T. 
Published: May 2017

AbstractDespite efforts to accurately quantify the effective radiative forcing (ERF) of anthropogenic aerosol, the historical evolution of ERF remains uncertain. As a further step toward a better understanding of ERF uncertainty, the present study systematically investigates the sensitivity of the shortwave ERF at the top of the atmosphere to model‐internal variability and spatial distributions of the monthly mean radiative effects of anthropogenic aerosol. For this, ensembles are generated with the atmospheric model ECHAM6.3 that uses monthly prescribed optical properties and changes in cloud‐droplet number concentrations designed to mimic that associated with the anthropogenic aerosol using the new parameterization MACv2‐SP. The results foremost highlight the small change in our best estimate of the global averaged all‐sky ERF associated with a substantially different pattern of anthropogenic aerosol radiative effects from the mid‐1970s (–0.51 Wm–2) and present day (–0.50 Wm–2). Such a small change in ERF is difficult to detect when model‐internal year‐to‐year variability (0.32 Wm–2 standard deviation) is considered. A stable estimate of all‐sky ERF requires ensemble simulations, the size of which depends on the targeted precision, confidence level, and the magnitude of model‐internal variability. A larger effect of the pattern of the anthropogenic aerosol radiative effects on the globally averaged all‐sky ERF (15%) occurs with a strong Twomey effect through lowering the background aerosol optical depth in regions downstream of major pollution sources. It suggests that models with strong aerosol‐cloud interactions could show a moderate difference in the global mean ERF associated with the mid‐1970s to present‐day change in the anthropogenic aerosol pattern.
Metal‐Organic Framework‐Derived Non‐Precious Metal Nanocatalysts for Oxygen Reduction Reaction
Authors: Fu Shaofang , Zhu Chengzhou , Song Junhua , Du Dan , Lin Yuehe 
Published: May 2017

AbstractBy virtue of diverse structures and tunable properties, metal‐organic frameworks (MOFs) have presented extensive applications including gas capture, energy storage, and catalysis. Recently, synthesis of MOFs and their derived nanomaterials provide an opportunity to obtain competent oxygen reduction reaction (ORR) electrocatalysts due to their large surface area, controllable composition and pore structure. This review starts with the introduction of MOFs and current challenges of ORR, followed by the discussion of MOF‐based non‐precious metal nanocatalysts (metal‐free and metal/metal oxide‐based carbonaceous materials) and their application in ORR electrocatalysis. Current issues in MOF‐derived ORR catalysts and some corresponding strategies in terms of composition and morphology to enhance their electrocatalytic performance are highlighted. In the last section, a perspective for future development of MOFs and their derivatives as catalysts for ORR is discussed.
Ein photoschaltbarer Ligand zur Regulierung der Rezeptoraktivierung
Authors: Agnetta Luca , Kauk Michael , Canizal Maria Consuelo Alonso , Messerer Regina , Holzgrabe Ulrike , Hoffmann Carsten , Decker Michael 
Published: May 2017

AbstractÜber die Art und den zeitlichen Verlauf der Aktivierung von G‐Protein‐gekoppelten Rezeptoren (GPCRs), insbesondere der muskarinischen Acetylcholinrezeptoren (mACh‐ oder M‐Rezeptoren), ist trotz der enormen therapeutischen Relevanz von M‐Rezeptoren und GPCRs wenig bekannt. In der vorliegenden Arbeit haben wir deshalb einen dualsteren Liganden eingesetzt, der sowohl mit der orthosteren Bindungsstelle des Rezeptors, d. h. derjenigen des Neurotransmitters, als auch mit einer allosteren Bindungsstelle interagiert, wobei synthetisch eine photoschaltbare (photochrome) Azobenzoleinheit eingebaut wurde. Wir haben die photophysikalischen Eigenschaften des BQCAAI benannten Liganden charakterisiert und seine Einsetzbarkeit als pharmakologisches Werkzeug mit einem Satz von FRET‐Techniken am M1‐Rezeptor untersucht. BQCAAI stellt den ersten photoschaltbaren dualsteren Liganden dar, und seine Aktivität kann durch Licht reguliert werden. Wir haben BQCAAI eingesetzt, um den zeitlichen Ablauf verschiedener Prozesse der Rezeptoraktivierung zu untersuchen.
Native Mass Spectrometry from Common Buffers with Salts That Mimic the Extracellular Environment
Authors: Susa Anna C. , Xia Zijie , Williams Evan R. 
Published: May 2017

AbstractNonvolatile salts are essential for the structures and functions of many proteins and protein complexes but can severely degrade performance of native mass spectrometry by adducting to protein and protein complex ions, thereby reducing sensitivity and mass measuring accuracy. Small nanoelectrospray emitters are used to form protein and protein complex ions directly from high‐ionic‐strength (>150 mm) nonvolatile buffers with salts that mimic the extracellular environment. Charge‐state distributions are not obtained for proteins and protein complexes from six commonly used nonvolatile buffers and ≥150 mm Na+ with conventionally sized nanoelectrospray emitter tips but are resolved with 0.5 μm tips. This method enables mass measurements of proteins and protein complexes directly from a variety of commonly used buffers with high concentrations of nonvolatile salts and eliminates the need to buffer exchange into volatile ammonium buffers traditionally used in native mass spectrometry.
Bioluminescent Antibodies for Point‐of‐Care Diagnostics
Authors: Xue Lin , Yu Qiuliyang , Griss Rudolf , Schena Alberto , Johnsson Kai 
Published: May 2017

AbstractWe introduce a general method to transform antibodies into ratiometric, bioluminescent sensor proteins for the no‐wash quantification of analytes. Our approach is based on the genetic fusion of antibody fragments to NanoLuc luciferase and SNAP‐tag, the latter being labeled with a synthetic fluorescent competitor of the antigen. Binding of the antigen, here synthetic drugs, by the sensor displaces the tethered fluorescent competitor from the antibody and disrupts bioluminescent resonance energy transfer (BRET) between the luciferase and fluorophore. The semisynthetic sensors display a tunable response range (submicromolar to submillimolar) and large dynamic range (ΔRmax>500 %), and they permit the quantification of analytes through spotting of the samples onto paper followed by analysis with a digital camera.
Mangan‐katalysierte nachhaltige Synthese von Pyrrolen aus Alkoholen und Aminoalkoholen
Authors: Kallmeier Fabian , Dudziec Beata , Irrgang Torsten , Kempe Rhett 
Published: May 2017

AbstractDie Entwicklung von Reaktionen, die Alkohole in wichtige chemische Verbindungen umwandeln, sichert die fossilen Kohlenstoffressourcen, da Alkohole aus unverdaulicher Biomasse wie Lignocellulose gewonnen werden können. Die Erhaltung der seltenen Edelmetalle ist von gleicher Bedeutung, und ihre Ersetzung durch reichlich vorhandene Übergangsmetalle wie Mn, Fe oder Co (Basismetalle oder mittlere 3d‐Metalle) in Schlüsseltechnologien wie der Katalyse ist eine vielversprechende Option. Hier wird die erste Basismetall‐katalysierte Synthese von Pyrrolverbindungen aus Alkoholen und Aminoalkoholen vorgestellt. Die effizientesten Katalysatoren sind PN5P‐Ligand‐stabilisierte Mn‐Komplexe. Verwandte Fe‐ und Co‐Komplexe sind inaktiv. Die unter milden Bedingungen ablaufende Reaktion mit Katalysatorbeladungen von nur 0.5 Mol‐% hat ein breites Spektrum und ist gut verträglich mit funktionellen Gruppen. Die Ergebnisse können andere dazu inspirieren, Mn‐Katalysatoren als Ir‐ oder Ru‐Ersatz in anspruchsvollen Dehydrierungskatalysen zu verwenden.
Enantioselective Borylation of Aromatic C−H Bonds with Chiral Dinitrogen Ligands
Authors: Su Bo , Zhou Tai‐Gang , Xu Pei‐Lin , Shi Zhang‐Jie , Hartwig John F. 
Published: May 2017

AbstractThe borylation of C−H bonds catalyzed by transition metals has been investigated extensively in the past two decades, but no iridium‐catalyzed enantioselective borylation of C−H bonds has been reported. We report a set of iridium‐catalyzed enantioselective borylations of aromatic C−H bonds. This reaction relies on a set of newly developed chiral quinolyl oxazoline ligands. This process proceeds under mild conditions with good to excellent enantioselectivity, and the borylated products can be converted to enantioenriched derivatives containing new C−O, C−C, C−Cl, or C−Br bonds.
Stereoselective Synthesis of Tetrasubstituted Alkenes via a Cp*CoIII‐Catalyzed C−H Alkenylation/Directing Group Migration Sequence
Authors: Ikemoto Hideya , Tanaka Ryo , Sakata Ken , Kanai Motomu , Yoshino Tatsuhiko , Matsunaga Shigeki 
Published: May 2017

AbstractA highly atom economical and stereoselective synthesis of tetrasubstituted α,β‐unsaturated amides was achieved by a Cp*CoIII‐catalyzed C−H alkenylation/directing group migration sequence. A carbamoyl directing group, which is typically removed after C−H functionalization, worked as an internal acylating agent and migrated onto the alkene moiety of the product. The directing group migration was realized with the Cp*CoIII catalyst, while a related Cp*RhIII catalyst did not promote the migration process. The product was further converted into two types of tricyclic compounds, one of which had fluorescent properties.
The Structural Fate of Individual Multicomponent Metal‐Oxide Nanoparticles in Polymer Nanoreactors
Authors: Du Jingshan S. , Chen Peng‐Cheng , Meckes Brian , Xie Zhuang , Zhu Jinghan , Liu Yuan , Dravid Vinayak P. , Mirkin Chad A. 
Published: May 2017

AbstractMulticomponent nanoparticles can be synthesized with either homogeneous or phase‐segregated architectures depending on the synthesis conditions and elements incorporated. To understand the parameters that determine their structural fate, multicomponent metal‐oxide nanoparticles consisting of combinations of Co, Ni, and Cu were synthesized by using scanning probe block copolymer lithography and characterized using correlated electron microscopy. These studies revealed that the miscibility, ratio of the metallic components, and the synthesis temperature determine the crystal structure and architecture of the nanoparticles. A Co‐Ni‐O system forms a rock salt structure largely owing to the miscibility of CoO and NiO, while Cu‐Ni‐O, which has large miscibility gaps, forms either homogeneous oxides, heterojunctions, or alloys depending on the annealing temperature and composition. Moreover, a higher‐ordered structure, Co‐Ni‐Cu‐O, was found to follow the behavior of lower ordered systems.
Triboluminescence of Lanthanide Coordination Polymers with Face‐to‐Face Arranged Substituents
Authors: Hirai Yuichi , Nakanishi Takayuki , Kitagawa Yuichi , Fushimi Koji , Seki Tomohiro , Ito Hajime , Hasegawa Yasuchika 
Published: May 2017

AbstractLuminescence upon the grinding of solid materials (triboluminescence, TL) has long been a puzzling phenomenon in natural science and has also attracted attention because of its broad application in optics. It has been generally considered that the TL spectra exhibit similar profiles as those of photoluminescence (PL), although they occur from distinct stimuli. Herein, we describe for the first time a large spectral difference between these two physical phenomena using lanthanideIII coordination polymers with efficient TL and PL properties. They are composed of emission centers (TbIII and EuIII ions), antenna (hexafluoroacetylacetonate=hfa), and bridging ligands (2,5‐bis(diphenylphosphoryl)furan=dpf). The emission color upon grinding (yellow TL) is clearly different from that upon UV irradiation (reddish‐orange PL) in TbIII/EuIII‐mixed coordination polymers [Tb,Eu(hfa)3(dpf)]n (Tb/Eu=1). The results directly indicate the discrete excitation processes of PL and TL.
Construction of the Benzomesembrine Skeleton: Palladium(0)‐Catalyzed Intermolecular Arylative Dearomatization of α‐Naphthols and Subsequent Aza‐Michael Reaction
Authors: Xu Ren‐Qi , Gu Qing , You Shu‐Li 
Published: May 2017

AbstractA novel palladium(0)‐catalyzed intermolecular arylative dearomatization of α‐naphthols and subsequent aza‐Michael reaction is described. Two adjacent stereocenters were constructed efficiently through consecutive arylative dearomatization and Michael addition reactions. By utilizing this method, structurally diverse benzomesembrine derivatives were synthesized with excellent yields and chemoselectivity. The benzomesembrine products were shown to undergo versatile functional‐group transformations.
Tricyanmethan und sein Ketenimin‐Tautomer: Bildung aus verschiedenen Vorstufen sowie Analyse in Lösung, in einer Argonmatrix und im Einkristall
Authors: Banert Klaus , Chityala Madhu , Hagedorn Manfred , Beckers Helmut , Stüker Tony , Riedel Sebastian , Rüffer Tobias , Lang Heinrich 
Published: May 2017

AbstractLösungen von Azidomethylidenmalononitril wurden bei tiefer Temperatur photolysiert, um das entsprechende 2H‐Azirin und Tricyanmethan zu bilden, was durch Tieftemperatur‐NMR‐Spektroskopie analysiert wurde. Das letztgenannte Produkt wurde auch nach kurzer Thermolyse einer Lösung der Azid‐Vorstufe beobachtet, während die Bestrahlung des in einer Argonmatrix isolierten Azids nicht zum Tricyanmethan, sondern erstmals zum zweifelsfreien Nachweis des tautomeren Ketenimins durch IR‐Spektroskopie führte. Wenn die lange bekannte, grünliche “aquoethereal” Phase, die aus Kaliumtricyanmethanid, verdünnter Schwefelsäure und Diethylether entsteht, rasch eingedampft und sublimiert wurde, resultierte statt des früher proklamierten Ketenimin‐Tautomers eine Mischung aus Hydroniumtricyanmethanid und Tricyanmethan. Unter speziellen Bedingungen ergab die Sublimation Einkristalle des Tricyanmethans, was die Analyse der Molekülstruktur mithilfe der Röntgenbeugung ermöglichte.
Substrate‐Specific Amino Acid Sensing Using a Molecular d/ l‐Cysteine Probe for Comprehensive Stereochemical Analysis in Aqueous Solution
Authors: Thanzeel F. Yushra , Wolf Christian 
Published: May 2017

AbstractThe appearance of d‐amino acids in mammals and humans has important implications in the life sciences. d/l‐Amino acid mixtures play a key role in human physiology and pathology; thus, the introduction of artificial receptors for the real‐time quantification of both the concentration and d/l composition of amino acids is very promising for the study of biological processes and for the diagnosis and treatment of diseases. We now report a sensing assay that is compatible with aqueous solutions and allows fast determination of the absolute configuration, enantiomeric composition, and overall amount of cysteine at micromolar concentrations. The method relies on fast UV and CD measurements, which provide accurate stereochemical information on samples covering a wide concentration range and drastically different d/l‐cysteine ratios in simulated body fluids. Competition experiments show that other amino acids and biothiols do not interfere with the cysteine‐targeted sensing.