bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mars's magnetotail: Nature's current sheet laboratory
Authors: Artemyev A. V. , Angelopoulos V. , Halekas J. S. , Runov A. , Zelenyi L. M. , McFadden J. P. 
Published: May 2017

AbstractThe configuration and stability of an important kinetic plasma structure, the current sheet, determine the efficiency of magnetic energy storage, release, and transport in surrounding plasmas. These properties depend on β (the ratio of plasma pressures to magnetic field pressures) and Mach number M (the ratio of bulk velocities to magnetosonic velocities). For the most investigated current sheet, the near‐Earth magnetotail current sheet, these parameters fall within a relatively narrow range of values (high β, low M). To investigate current sheet behavior for a wider range of parameters, we explore current sheets in the magnetotail of Mars using Mars Atmosphere and Volatile Evolution (MAVEN) mission observations. We find that low‐β, high‐M current sheets are abundant in Mars's magnetotail, but high‐β, low‐M current sheets can also be found there. Low‐β current sheets are nearly force‐free, whereas high‐M current sheets are balanced by a plasma flow gradient along the tail. We compare current sheet distributions in a (β,M) space for the Martian magnetotail, the near‐Earth magnetotail (using Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission), and the distant magnetotail (using Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission). We also find that the pressure balance in the Martian magnetotail current sheet can occur by contributions from a wide range of ion species, or, in low beta cases, from field‐aligned currents generation of a force‐free magnetic field configuration. The Martian magnetotail is a natural laboratory where current sheet of various types can be found and investigated.
Nonlinear Landau resonance with localized wave pulses
Authors: Artemyev A. V. , Rankin R. , Vasko I. Y. 
Published: May 2017

AbstractWave‐particle resonant interaction is responsible for many important space plasma processes and can be formally described theoretically for two main regimes: particle scattering (quasilinear diffusion) by low‐intensity waves and particle trapping/phase bunching by sufficiently intense waves. There are important modifications of these regimes in inhomogeneous plasma systems. However, almost all theoretical results have been derived for harmonic waves and linear plasma modes. High‐resolution spacecraft measurements of spatially localized plasma waves in Earth's magnetosphere demonstrate electron acceleration attributed to the Landau resonance mechanism. In the classical mechanism, the magnitude of the electric potential determines the maximum energy gain of electrons. However, a less reported mechanism of electron acceleration becomes possible in inhomogeneous plasma and magnetic field. In this Commentary, we discuss how combination of wave localization and plasma inhomogeneity modifies the nonlinear Landau resonance. We underline the important property of this resonance: an electron energy gain depends on the gradient in wave potential and not just its magnitude. We also consider this modified resonance mechanism in context of generation of hot field‐aligned electron populations, particle transport, and energy transfer in the magnetosphere.
Low‐frequency electromagnetic cyclotron waves in and around magnetic clouds: STEREO observations during 2007–2013
Authors: Zhao G. Q. , Chu Y. H. , Lin P. H. , Yang Y. H. , Feng H. Q. , Wu D. J. , Liu Q. 
Published: May 2017

AbstractWave activities in the solar wind are an important topic and magnetic clouds (MCs) are a common phenomenon in interplanetary space, though waves activities associated with MCs have not been well documented. Based on a survey of 120 MCs observed by STEREO spacecraft during the years 2007–2013, this work studies electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency in and around MCs. For total 7807 ECW events, 24% of them occurred in the regions within MCs while 76% occurred in the regions around MCs. Statistics indicate that ECWs around MCs have higher frequencies, wider bandwidths, and stronger powers relative to the waves in MCs. More ECWs, on the other hand, tend to be related to a plasma with higher temperature, lower density, and larger velocity. In particular, it is found that there exist positive power law correlations between plasma betas and the wave frequencies, bandwidths, and powers. The results imply that the plasma beta should play an important role in determining the properties of ECWs, which is consistent with previous theory studies and the recent simulation results.
Reexamining ultrafiltration and solute transport in groundwater
Authors: Neuzil C. E. , Person Mark 
Published: May 2017

AbstractGeologic ultrafiltration—slowing of solutes with respect to flowing groundwater—poses a conundrum: it is consistently observed experimentally in clay‐rich lithologies, but has been difficult to identify in subsurface data. Resolving this could be important for clarifying clay and shale transport properties at large scales as well as interpreting solute and isotope patterns for applications ranging from nuclear waste repository siting to understanding fluid transport in tectonically active environments. Simulations of one‐dimensional NaCl transport across ultrafiltering clay membrane strata constrained by emerging data on geologic membrane properties showed different ultrafiltration effects than have often been envisioned. In relatively high‐permeability advection‐dominated regimes, salinity increases occurred mostly within membrane units while their effluent salinity initially fell and then rose to match solute delivery. In relatively low‐permeability diffusion‐dominated regimes, salinity peaked at the membrane upstream boundary and effluent salinity remained low. In both scenarios, however, only modest salinity changes (up to ∼3 g L−1) occurred because of self‐limiting tendencies; membrane efficiency declines as salinity rises, and although sediment compaction increases efficiency, it is also decreases permeability and allows diffusive transport to dominate. It appears difficult for ultrafiltration to generate brines as speculated, but widespread and less extreme ultrafiltration effects in the subsurface could be unrecognized. Conditions needed for ultrafiltration are present in settings that include topographically‐driven flow systems, confined aquifer systems subjected to injection or withdrawal, compacting basins, and accretionary complexes.
Immune and myodegenerative pathomechanisms in inclusion body myositis
Authors: Keller Christian W. , Schmidt Jens , Lünemann Jan D. 
Published: May 2017

AbstractInclusion Body Myositis (IBM) is a relatively common acquired inflammatory myopathy in patients above 50 years of age. Pathological hallmarks of IBM are intramyofiber protein inclusions and endomysial inflammation, indicating that both myodegenerative and inflammatory mechanisms contribute to its pathogenesis. Impaired protein degradation by the autophagic machinery, which regulates innate and adaptive immune responses, in skeletal muscle fibers has recently been identified as a potential key pathomechanism in IBM. Immunotherapies, which are successfully used for treating other inflammatory myopathies lack efficacy in IBM and so far no effective treatment is available. Thus, a better understanding of the mechanistic pathways underlying progressive muscle weakness and atrophy in IBM is crucial in identifying novel promising targets for therapeutic intervention. Here, we discuss recent insights into the pathomechanistic network of mutually dependent inflammatory and degenerative events during IBM.
Effect of Fatigue, Older Age, Higher Body Mass Index, and Female Sex on Disability in Early Rheumatoid Arthritis in the Treatment‐to‐Target Era
Authors: Twigg Sarah , Hensor Elizabeth M. A. , Freeston Jane , Tan Ai Lyn , Emery Paul , Tennant Alan , Morgan Ann W. ,   the YEAR and IACON Consortia
Published: May 2017

ObjectiveTo compare disease activity and disability over 2 years in early rheumatoid arthritis (RA) before and after implementation of treat‐to‐target therapy and identify predictors of adverse outcome.MethodsThe Yorkshire Early Arthritis Register (YEAR) recruited 725 patients with early RA between 2002 and 2009, treated with a step‐up approach. The Inflammatory Arthritis Continuum study (IACON) recruited cases between 2010 and 2014 and treated to target. A total of 384 IACON cases met 2010 American College of Rheumatology/European League Against Rheumatism criteria. Latent growth curves of change in Disease Activity Score in 28 joints (DAS28) and the Health Assessment Questionnaire (HAQ) were compared between YEAR and IACON. Latent class growth analysis identified trajectories of change. Baseline predictors of trajectories were identified using logistic regression.ResultsThe mean DAS28 over 2 years was lower in IACON than in YEAR. Latent trajectories of HAQ change in YEAR were high stable (21% of cohort), moderate reducing (35%), and low reducing (44%). Only moderate reducing (66%) and low reducing (34%) were seen in IACON. In both cohorts, female sex and fatigue predicted adverse HAQ trajectories (high stable and moderate reducing). Odds ratios (ORs) for moderate reducing compared to low reducing for women were 2.58 (95% confidence interval [95% CI] 1.69, 4.49) in YEAR and 5.81 (95% CI 2.44, 14.29) in IACON. ORs per centimeter fatigue visual analog score were 1.13 (95% CI 1.07, 1.20) in YEAR and 1.16 (95% CI 1.12, 1.20) in IACON.ConclusionTreat‐to‐target therapy gave more favorable trajectories of change in DAS28 and HAQ, but adverse HAQ trajectory was more likely in women with greater fatigue, suggesting such patients would benefit from interventions to improve function as well as reduce inflammation.
Gold(I)‐catalyzed synthesis of dihydrodibenzoquinolizinium salts
Authors: Marien Niels , Verniest Guido 
Published: May 2017

AbstractA gold‐catalyzed cyclization of 1‐alkynyl‐2‐aryl tetrahydroisoquinolines is described for the synthesis of novel dihydrodibenzoquinolizinium salts. The reaction mechanism is likely to involve a 6‐endo‐dig cyclization and subsequent oxidation by air to give a relatively stable arylgold intermediate. This gold species undergoes protodeauration under acidic conditions to afford the title compounds. An NMR study was performed to gain further evidence and insight on the presence of the arylgold intermediate and the reaction mechanism.magnified image
Substratspezifische Analyse von Aminosäuren mit Sensoren für d/ l‐Cystein: umfassende stereochemische Untersuchungen in wässriger Lösung
Authors: Thanzeel F. Yushra , Wolf Christian 
Published: May 2017

AbstractDas Auftreten von d‐Aminosäuren in Säugern und im Menschen ist von großer Bedeutung für die Lebenswissenschaften. d/l‐Aminosäuremischungen spielen eine Schlüsselrolle bei der menschlichen Physiologie und Pathologie; daher ist die Einführung künstlicher Rezeptoren für die Echtzeitquantifizierung der Konzentration und des d/l‐Verhältnisses von Aminosäuren vielversprechend für das Studium biologischer Prozesse und die Diagnose sowie Behandlung von Krankheiten. Die hier vorgestellte Detektionsmethode ist kompatibel mit wässrigen Lösungen und ermöglicht die rasche Bestimmung der absoluten Konfiguration, des ee‐Werts und der Gesamtmenge von Cystein bei mikromolaren Konzentrationen. Die Methode beruht auf schnellen UV‐ und CD‐Messungen, die akkurate stereochemische Informationen mit Proben über einen weiten Konzentrationsbereich und mit stark unterschiedlichen d/l‐Cysteinverhältnissen in simulierten Körperflüssigkeiten liefern. Konkurrenzexperimente zeigen, dass andere Aminosäuren und Biothiole die gezielte Cysteinanalyse nicht stören.
Polyoxometalate‐Engineered Building Blocks with Gold Cores for the Self‐Assembly of Responsive Water‐Soluble Nanostructures
Authors: Wang Yizhan , Raula Manoj , Wang Yifeng , Zeiri Offer , Chakraborty Sourav , Gan‐Or Gal , Gadot Eyal , Weinstock Ira A. 
Published: May 2017

AbstractThe controlled assembly of gold nanoparticles (AuNPs) with the size of quantum dots into predictable structures is extremely challenging as it requires the quantitatively and topologically precise placement of anisotropic domains on their small, approximately spherical surfaces. We herein address this problem by using polyoxometalate leaving groups to transform 2 nm diameter gold cores into reactive building blocks with hydrophilic and hydrophobic surface domains whose relative sizes can be precisely tuned to give dimers, clusters, and larger micelle‐like organizations. Using cryo‐TEM imaging and 1H DOSY NMR spectroscopy, we then provide an unprecedented “solution‐state” picture of how the micelle‐like structures respond to hydrophobic guests by encapsulating them within 250 nm diameter vesicles whose walls are comprised of amphiphilic AuNP membranes. These findings provide a versatile new option for transforming very small AuNPs into precisely tailored building blocks for the rational design of functional water‐soluble assemblies.
A Carbon Dioxide Bubble‐Induced Vortex Triggers Co‐Assembly of Nanotubes with Controlled Chirality
Authors: Zhang Ling , Zhou Laicheng , Xu Na , Ouyang Zhenjie 
Published: May 2017

AbstractIt is challenging to prepare co‐organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO2) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co‐assembled in aqueous solution. CO2‐triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self‐assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO2 bubble‐induced vortex during the co‐assembly process.
Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode
Authors: Qie Long , Lin Yi , Connell John W. , Xu Jiantie , Dai Liming 
Published: May 2017

AbstractMetal‐air batteries, especially Li‐air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO2 (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li2CO3, making the battery less rechargeable. To make the Li‐CO2 batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO2 reduction and evolution reactions and investigate the electrochemical behavior of Li‐CO2 batteries. Here, we demonstrate a rechargeable Li‐CO2 battery with a high reversibility by using B,N‐codoped holey graphene as a highly efficient catalyst for CO2 reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as‐prepared Li‐CO2 batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long‐term cycling stability over 200 cycles at a high current density of 1.0 A g−1. Our results open up new possibilities for the development of long‐term Li‐air batteries reusable under ambient conditions, and the utilization and storage of CO2.
Crystal‐Packing‐Driven Enrichment of Atropoisomers
Authors: Sharafi Mona , Campbell Joseph P. , Rajappan Sinu C. , Dudkina Natavan , Gray Danielle L. , Woods Toby J. , Li Jianing , Schneebeli Severin T. 
Published: May 2017

AbstractCrystal‐packing forces can have a significant impact on the relative stabilities of different molecules and their conformations. The magnitude of such effects is, however, not yet well understood. Herein we show, that crystal packing can completely overrule the relative stabilities of different stereoisomers in solution. Heating of atropoisomers (i.e. “frozen‐out” conformational isomers) in solution leads to complex mixtures. In contrast, solid‐state heating selectively amplifies minor (<25 mole %) components of these solution‐phase mixtures. We show that this heating strategy is successful for compounds with up to four rotationally hindered σ bonds, for which a single stereoisomer out of seven can be amplified selectively. Our results demonstrate that common supramolecular interactions—for example, [methyl⋅⋅⋅π] coordination and [C−H⋅⋅⋅O] hydrogen bonding—can readily invert the relative thermodynamic stabilities of different molecular conformations. These findings open up potential new avenues to control the folding of macromolecules.
Synthesis of an Aluminum Hydroxide Octamer through a Simple Dissolution Method
Authors: Perkins Cory K. , Eitrheim Eric S. , Fulton Brantly L. , Fullmer Lauren B. , Colla Christopher A. , Park Deok‐Hie , Oliveri Anna F. , Hutchison James E. , Nyman May , Casey William H. , Forbes Tori Z. , Johnson Darren W. , Keszler Douglas A. 
Published: May 2017

AbstractMultimeric oxo‐hydroxo Al clusters function as models for common mineral structures and reactions. Cluster research, however, is often slowed by a lack of methods to prepare clusters in pure form and in large amounts. Herein, we report a facile synthesis of the little known cluster Al8(OH)14(H2O)18(SO4)5 (Al8) through a simple dissolution method. We confirm its structure by single‐crystal X‐ray diffraction and show by 27Al NMR spectroscopy, electrospray‐ionization mass spectrometry, and small‐ and wide‐angle X‐ray scattering that it also exists in solution. We speculate that Al8 may form in natural water systems through the dissolution of aluminum‐containing minerals in acidic sulfate solutions, such as those that could result from acid rain or mine drainage. Additionally, the dissolution method produces a discrete Al cluster on a scale suitable for studies and applications in materials science.
Selektive Si‐C(sp3)‐Bindungsspaltung in (Aminomethyl)silanen durch carbanionische Nucleophile und ihr stereochemischer Verlauf
Authors: Koller Stephan G. , Bauer Jonathan O. , Strohmann Carsten 
Published: May 2017

AbstractDie Nutzbarmachung von Tetraorganosilanen durch gezielte Spaltung einer Si‐C‐Bindung ist noch immer eine anspruchsvolle Aufgabe. Nun wurde ein neuer Typ von Si‐C(sp3)‐Bindungsspaltungen in stabilen (Aminomethyl)silanen mit gewöhnlichen Organolithiumreagentien als Nucleophilen gefunden. Als Abgangsgruppen eignen sich Benzyl‐, Allyl‐ und Phenylthiomethylgruppen. Ein β‐ständiges Donoratom und polare Lösungsmittel sind essenziell für die Reaktion. Durch eine einfache Änderung der Reaktionsbedingungen kann zwischen einer α‐Deprotonierung und einer Substitution umgeschaltet werden. Anhand eines siliciumchiralen Benzylsilans wurde der stereochemische Verlauf der Reaktion aufgeklärt. Die neue Umsetzung verläuft stereospezifisch unter Inversion der Konfiguration und eignet sich für eine zielgerichtete Synthese schwer zugänglicher, enantiomerenreiner Tetraorganosilane. Quantenchemische Rechnungen liefern einen Einblick in den Mechanismus der neuartigen Substitution.
Structural Dynamics upon Photoexcitation in a Spin Crossover Crystal Probed with Femtosecond Electron Diffraction
Authors: Jiang Yifeng , Liu Lai Chung , Müller‐Werkmeister Henrike M. , Lu Cheng , Zhang Dongfang , Field Ryan L. , Sarracini Antoine , Moriena Gustavo , Collet Eric , Miller R. J. Dwayne 
Published: May 2017

AbstractPhotoexcitation of spin crossover (SCO) complexes can trigger extensive electronic spin transitions and transformation of molecular structure. However, the precise nature of the associated ultrafast structural dynamics remains elusive, especially in the solid state. Here, we studied a single‐crystal SCO material with femtosecond electron diffraction (FED). The unique capability of FED allows us to directly probe atomic motions and to track ultrafast structural changes within a crystal lattice. By monitoring the time‐dependent changes of the Bragg reflections, we observed the formation of a photoinduced structure similar to the thermally induced high‐spin state. The data and refinement calculations indicate the global structural reorganization within 2.3 ps, as the metal–ligand bond distribution narrows during intramolecular vibrational energy redistribution (IVR) driving the intermolecular rearrangement. Three independent dynamical group are identified to model the structural dynamics upon photoinduced SCO.
Durch Cp*Fe‐Fragmente stabilisierte, Arsen‐reiche Polyarsenide
Authors: Schmidt Monika , Konieczny David , Peresypkina Eugenia V. , Virovets Alexander V. , Balázs Gabor , Bodensteiner Michael , Riedlberger Felix , Krauss Hannes , Scheer Manfred 
Published: May 2017

AbstractDie Untersuchung der Redoxchemie von [Cp*Fe(η5‐As5)] (1) (Cp*=η5‐C5Me5) mittels Cyclovoltammetrie ergab ein Redoxverhalten, das jenem des leichteren Verwandten [Cp*Fe(η5‐P5)] ähnelt. Die anschließende chemische Reduktion von 1 durch KH führt zur Bildung eines Gemisches von Produkten mit neuartigen Asn‐Gerüsten (n=bis zu 18), die lediglich durch [Cp*Fe]‐Fragmente stabilisiert werden. Dazu gehören der Arsen‐arme Tripeldeckerkomplex [K(dme)2][{Cp*Fe(μ,η2:2‐As2)}2] (2) und die Arsen‐reichen Komplexe [K(dme)3]2[(Cp*Fe)2(μ,η4:4‐As10)] (3), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2‐As14)] (4) sowie [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1‐As18)] (5). 4 und der Polyarsenidkomplex 5 enthalten die bisher größten publizierten anionischen Asn‐Liganden. Die Komplexe 2–5 wurden durch Einkristall‐Röntgenstrukturanalyse, 1H‐NMR‐Spektroskopie, EPR‐Spektroskopie (2) und Massenspektrometrie charakterisiert. Darüber hinaus zeigten DFT‐Rechnungen eine schnelle Dimerisierung des mutmaßlich zuerst gebildeten Intermediates [Cp*Fe(η5‐As5)]− zum Dianion [(Cp*Fe)2(μ,η4:4‐As10)]2−.
Exploring the Molecular Growth of Two Gigantic Half‐Closed Polyoxometalate Clusters {Mo180} and {Mo130Ce6}
Authors: Xuan Weimin , Pow Robert , Long De‐Liang , Cronin Leroy 
Published: May 2017

AbstractUnderstanding the process of the self‐assembly of gigantic polyoxometalates and their subsequent molecular growth, by the addition of capping moieties onto the oxo‐frameworks, is critical for the development of the designed assembly of complex high‐nuclearity cluster species, yet such processes remain far from being understood. Herein we describe the molecular growth from {Mo150} and {Mo120Ce6} to afford two half‐closed gigantic molybdenum blue clusters {Mo180} (1) and {Mo130Ce6} (2), respectively. Compound 1 features a hat‐shaped structure with the parent wheel‐shaped {Mo150} being capped by a {Mo30} unit on one side. Similarly, 2 exhibits an elliptical lanthanide‐doped wheel {Mo120Ce6} that is sealed by a {Mo10} unit on one side. Moreover, the observation of the parent uncapped {Mo150} and {Mo120Ce6} clusters as minor products during the synthesis of 1 and 2 strongly suggests that the molecular growth process can be initialized from {Mo150} and {Mo120Ce6} in solution, respectively.
Iridium‐Catalyzed Formyl‐Selective Deuteration of Aldehydes
Authors: Kerr William J. , Reid Marc , Tuttle Tell 
Published: May 2017

AbstractWe report the first direct catalytic method for formyl‐selective deuterium labeling of aromatic aldehydes under mild conditions, using an iridium‐based catalyst designed to favor formyl over aromatic C−H activation. A good range of aromatic aldehydes is selectively labeled, and a one‐pot labeling/olefination method is also described. Computational studies support kinetic product control over competing aromatic labeling and decarbonylation pathways.