bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substorm evolution of auroral structures
Authors: Partamies N. , Juusola L. , Whiter D. , Kauristie K. 
Published: June 2015

AbstractAuroral arcs are often associated with magnetically quiet time and substorm growth phases. We have studied the evolution of auroral structures during global and local magnetic activity to investigate the occurrence rate of auroral arcs during different levels of magnetic activity. The ground‐magnetic and auroral conditions are described by the magnetometer and auroral camera data from five Magnetometers — Ionospheric radars — All‐sky cameras Large Experiment stations in Finnish and Swedish Lapland. We identified substorm growth, expansion, and recovery phases from the local electrojet index (IL) in 1996–2007 and analyzed the auroral structures during the different phases. Auroral structures were also analyzed during different global magnetic activity levels, as described by the planetary Kp index. The distribution of auroral structures for all substorm phases and Kp levels is of similar shape. About one third of all detected structures are auroral arcs. This suggests that auroral arcs occur in all conditions as the main element of the aurora. The most arc‐dominated substorm phases occur in the premidnight sector, while the least arc‐dominated substorm phases take place in the dawn sector. Arc event lifetimes and expectation times calculated for different substorm phases show that the longest arc‐dominated periods are found during growth phases, while the longest arc waiting times occur during expansion phases. Most of the arc events end when arcs evolve to more complex structures. This is true for all substorm phases. Based on the number of images of auroral arcs and the durations of substorm phases, we conclude that a randomly selected auroral arc most likely belongs to a substorm expansion phase. A small time delay, of the order of a minute, is observed between the magnetic signature of the substorm onset (i.e., the beginning of the negative bay) and the auroral breakup (i.e., the growth phase arc changing into a dynamic display). The magnetic onset was observed to precede the structural change in the auroral display. A longer delay of a few minutes was found between the beginning of the growth phase and the first detected auroral structure.
Fresh and evolutionary‐type field‐aligned irregularities generated near sunrise terminator due to overshielding electric fields
Authors: Tulasi Ram S. , Ajith K. K. , Yamamoto M. , Otsuka Y. , Yokoyama T. , Niranjan K. , Gurubaran S. 
Published: June 2015

AbstractThe unusual evolution of fresh and intense field‐aligned irregularities (FAI) near sunrise terminator which further sustained for more than 90 min of postsunrise period was observed by Equatorial Atmosphere Radar at Kototabang during a minor geomagnetic storm period. These FAI echoes were initially observed around 250–350 km altitudes, growing upward under eastward polarization electric fields indicating the plasma bubbles that are fully depleted along the flux tube. The background low‐latitude F layer dynamics that lead to the development of these dawn time FAI have been investigated from two ionosondes at near magnetic conjugate low‐latitude locations. A minor geomagnetic storm was in progress which did not appear to cause any large electric field perturbations at preceding postsunset to midnight period over Indonesian sector. However, the prompt penetration of overshielding electric fields associated with sudden northward turning of interplanetary magnetic field Bz caused spectacular ascent of F layer and development of fresh, intense, and upward evolutionary plasma bubbles near sunrise terminator.
The Palos Verdes Fault offshore Southern California: Late Pleistocene to present tectonic geomorphology, seascape evolution, and slip rate estimate based on AUV and ROV surveys
Authors: Brothers Daniel S. , Conrad James E. , Maier Katherine L. , Paull Charles K. , McGann Mary , Caress David W. 
Published: June 2015

AbstractThe Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near‐seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high‐resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship‐based gravity cores. The PVF is expressed as a well‐defined seafloor lineation marked by subtle along‐strike bends. Right‐stepping transtensional bends exert first‐order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull‐apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right‐laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17–24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3–2.8 mm/yr and provide a best estimate of 1.6–1.9 mm/yr. The deformation observed along the PVF is characteristic of strike‐slip faulting and accounts for 20–30% of the total right‐lateral slip budget accommodated offshore Southern California.
Kovalent‐allosterische Kinase‐Inhibitoren
Authors: Weisner Jörn , Gontla Rajesh , van der Westhuizen Leandi , Oeck Sebastian , Ketzer Julia , Janning Petra , Richters André , Mühlenberg Thomas , Fang Zhizhou , Taher Abu , Jendrossek Verena , Pelly Stephen C. , Bauer Sebastian , van Otterlo Willem A. L. , Rauh Daniel 
Published: June 2015

AbstractProteinkinasen repräsentieren wichtige Knotenpunkte intrazellulärer Signalwege und sind somit an vielen physiologischen und pathologischen Prozessen beteiligt. Konformations‐abhängige Eigenschaften dienen hierbei der Feinregulation ihrer enzymatischen Aktivität und Katalyse‐unabhängigen Funktionen. Die Stabilisierung definierter Konformationen ermöglicht detaillierte Analysen solcher Konformations‐abhängiger Funktionen. Hier beschreiben wir das strukturbasierte Design, die Synthese und die Charakterisierung Pleckstrin‐Homologie(PH)‐Domänen‐abhängiger Akt‐Inhibitoren, die einen neuartigen kovalent‐allosterischen Bindungsmodus aufweisen. Durch die kovalente Modifizierung bestimmter Cysteine stabilisieren diese Moleküle die inaktive Kinasekonformation irreversibel. Ihre beträchtliche Inhibitorwirkung und Selektivität bezüglich verwandter Proteinkinasen machen sie zu einem neuartigen Hilfsmittel für die Erforschung chemisch‐biologischer und medizinischer Fragestellungen.
Einfluss der Solvatisierung auf die Elektronenanlagerung an Pyrimidin
Authors: Neustetter Michael , Aysina Julia , da Silva Filipe Ferreira , Denifl Stephan 
Published: June 2015

AbstractDie Wechselwirkung niederenergetischer Elektronen mit Biomolekülen spielt eine wichtige Rolle bei der strahlungsinduzierten Mutation von biologischem Gewebe auf molekularer Ebene. Bei Elektronenenergien unter 15 eV ist die dissoziative Elektronenanlagerung einer der Hauptprozesse, die chemische Umwandlungen von Molekülen induzieren. Bisherige Gasphasenstudien hinsichtlich der ablaufenden Prozesse auf molekularer Ebene wurden mit einzelnen Biomolekülbausteinen wie Pyrimidin als Modellmolekül durchgeführt. Hier wurde die Elektronenanlagerung sowohl an einzelnen Pyrimidinmolekülen als auch reinen oder hydratisierten Clustern untersucht. Im Unterschied zum isolierten und hydratisierten Fall, in denen kein anionisches Monomer detektiert werden konnte, gelang es, das Molekülanion bei reinen Clustern zu beobachten. Zusätzlich gibt es Hinweise darauf, dass die Fragmentierung des Pyrimidinrings unter Elektroneneinfang durch Solvatisierung effizient unterdrückt wird.
Synthesis of Previously Inaccessible Borylated Heterocycle Motifs Using Novel Boron‐Containing Amphoteric Molecules
Authors: Trinchera Piera , Corless Victoria B. , Yudin Andrei K. 
Published: June 2015

AbstractThe photoredox‐organocatalyzed α‐alkylation of the α‐MIDA boryl aldehyde with a range of α‐bromoketones resulted in the first examples of boron‐containing 1,4‐dicarbonyl compounds. These novel trifunctional amphoteric molecules, which bear an additional, strategically placed electrophilic site compared to the starting amphoteric α‐boryl aldehyde, were subjected to double‐condensation reactions in the presence of various nucleophiles. As a result, a variety of synthetically challenging 3‐borylated pyrroles and furans and 4‐borylated pyridazines were generated. The borylated regioisomers accessible with this condensation‐based strategy are distinctly different from those arising from the well‐known lithiation and CH activation processes.
Asymmetric Donor–π‐Acceptor‐Type Benzo‐Fused Aza‐BODIPYs: Facile Synthesis and Colorimetric Properties
Authors: Zheng Wei , Wang Bei‐Bei , Li Cheng‐Hui , Zhang Jing‐Xuan , Wan Cheng‐Zhang , Huang Jia‐Hao , Liu Jian , Shen Zhen , You Xiao‐Zeng 
Published: June 2015

AbstractNovel aza‐diisoindolylmethene and their BF2‐chelating complexes (benzo‐fused aza‐BODIPYs) were synthesized on a large scale and in a facile manner from phthalonitrile in tBuOK‐DMF solution. The unique asymmetric donor–π‐acceptor structure facilitates BN bond detachment in the presence of trifluoroacetic acid (TFA) in dichloromethane, resulting in sharp color change from red to colorless, with over 250 nm hypsochromic shift in the absorption maximum. This colorimetric process can be reversed by adding a very small amount of proton‐accepting solvents or compounds. A 1H and 11B NMR spectroscopy study and also density functional theory (DFT) calculations suggest that TFA‐induced BN bond cleavage may disrupt the whole π‐conjugation of the BODIPY molecule, resulting in significant colorimetric behavior.
Covalent‐Allosteric Kinase Inhibitors
Authors: Weisner Jörn , Gontla Rajesh , van der Westhuizen Leandi , Oeck Sebastian , Ketzer Julia , Janning Petra , Richters André , Mühlenberg Thomas , Fang Zhizhou , Taher Abu , Jendrossek Verena , Pelly Stephen C. , Bauer Sebastian , van Otterlo Willem A. L. , Rauh Daniel 
Published: June 2015

AbstractTargeting and stabilizing distinct kinase conformations is an instrumental strategy for dissecting conformation‐dependent signaling of protein kinases. Herein the structure‐based design, synthesis, and evaluation of pleckstrin homology (PH) domain‐dependent covalent‐allosteric inhibitors (CAIs) of the kinase Akt is reported. These inhibitors bind covalently to a distinct cysteine of the kinase and thereby stabilize the inactive kinase conformation. These modulators exhibit high potency and selectivity, and represent an innovative approach for chemical biology and medicinal chemistry research.
Highly Enantioselective Nucleophilic Dearomatization of Pyridines by Anion‐Binding Catalysis
Authors: García Mancheño Olga , Asmus Sören , Zurro Mercedes , Fischer Theresa 
Published: June 2015

AbstractThe asymmetric dearomatization of N‐heterocycles is an important synthetic method to gain bioactive and synthetically valuable chiral heterocycles. However, the catalytic enantio‐ and regioselective dearomatization of the simplest six‐membered‐ring N‐heteroarenes, the pyridines, is still very challenging. The first anion‐binding‐catalyzed, highly enantioselective nucleophilic dearomatization of pyridines with triazole‐based H‐bond donor catalysts is presented. Contrary to other more common NH‐based H‐bond donors, this type of organocatalyst shows a prominent higher C2‐regioselectivity and is able to promote high enantioinductions via formation of a close chiral anion‐pair complex with a preformed N‐acyl pyridinium ionic intermediate. This method offers a straightforward and useful synthetic approach to chiral N‐heterocycles from abundant and readily available pyridines.
Atomic‐Layer‐Confined Doping for Atomic‐Level Insights into Visible‐Light Water Splitting
Authors: Lei Fengcai , Zhang Lei , Sun Yongfu , Liang Liang , Liu Katong , Xu Jiaqi , Zhang Qun , Pan Bicai , Luo Yi , Xie Yi 
Published: June 2015

AbstractA model of doping confined in atomic layers is proposed for atomic‐level insights into the effect of doping on photocatalysis. Co doping confined in three atomic layers of In2S3 was implemented with a lamellar hybrid intermediate strategy. Density functional calculations reveal that the introduction of Co ions brings about several new energy levels and increased density of states at the conduction band minimum, leading to sharply increased visible‐light absorption and three times higher carrier concentration. Ultrafast transient absorption spectroscopy reveals that the electron transfer time of about 1.6 ps from the valence band to newly formed localized states is due to Co doping. The 25‐fold increase in average recovery lifetime is believed to be responsible for the increased of electron–hole separation. The synthesized Co‐doped In2S3 (three atomic layers) yield a photocurrent of 1.17 mA cm−2 at 1.5 V vs. RHE, nearly 10 and 17 times higher than that of the perfect In2S3 (three atomic layers) and the bulk counterpart, respectively.
The Effect of Solvation on Electron Attachment to Pure and Hydrated Pyrimidine Clusters
Authors: Neustetter Michael , Aysina Julia , da Silva Filipe Ferreira , Denifl Stephan 
Published: June 2015

AbstractThe interaction of low‐energy electrons with biomolecules plays an important role in the radiation‐induced alteration of biological tissue at the molecular level. At electron energies below 15 eV, dissociative electron attachment is one of the most important processes in terms of the chemical transformation of molecules. So far, a common approach to study processes at the molecular level has been to carry out investigations with single biomolecular building blocks like pyrimidine as model molecules. Electron attachment to single pyrimidine, as well as to pure clusters and hydrated clusters, was investigated in this study. In striking contrast to the situation with isolated molecules and hydrated clusters, where no anionic monomer is detectable, we were able to observe the molecular anion for the pure clusters. Furthermore, there is evidence that solvation effectively prevents the ring fragmentation of pyrimidine after electron capture.
Light‐ and Humidity‐Induced Motion of an Acidochromic Film
Authors: Zhang Lidong , Naumov Panče 
Published: June 2015

AbstractA smart acidochromic agarose‐based film with 1,4‐bis(para‐hydroxystyryl)benzene as the pH‐responsive fluorophore was prepared. This film can simultaneously harness the chemical potential of light and aerial humidity gradients to convert them into mechanical work. The strong reversible hygroscopicity of the agarose matrix induces swift locomotion by mechanical deformation owing to exchange of water with the surroundings. Driven by humidity, a 20 mg composite film coupled to a piezoelectric bending transducer sensor generates a peak output of approximately 80 mV, which corresponds to a power density of 25 μW kg−1. Excitation with UV light triggers isomerization of the chromophore, which appears as reshaping by spiraling, bending, or twisting of the film. The material also responds to changes in the pH value by reversible protonation of the fluorophore with rapid changes in color and fluorescence. The threefold sensing capability of this smart material could be utilized for the fabrication of multiresponsive actuating dynamic elements in biomedicine and soft robotics.
Metal–Organic Frameworks Incorporating Various Alkoxy Pendant Groups: Hollow Tubular Morphologies, X‐ray Single‐Crystal Structures, and Selective Carbon Dioxide Adsorption Properties
Authors: Prasad Thazhe Kootteri , Suh Myunghyun Paik 
Published: June 2015

AbstractEight porous metal–organic frameworks (MOFs) incorporating various alkoxy pendant groups (−OCnH2n+1; n=1–8) in the channels have been synthesized. All MOFs have macrosized, hollow, single‐crystal morphologies independent of the type of alkoxy pendant groups. The X‐ray single‐crystal structures indicate that the MOFs have doubly interpenetrated 3D frameworks that generate clover‐shaped 1D channels, the window sizes of which reduce as the length of the alkoxy pendant groups increases from −OCH3 to −OC8H17. The hollow axes of the tubular crystals are parallel to the 1D channels of the MOFs, which suggests that the hollow crystal is grown by the unidirectional addition of pillar ligands to the 2D network. Among the activated MOFs, only the MOFs with methoxy and ethoxy pendant groups show selective CO2 adsorption over N2 and CH4, whereas those with longer alkoxy pendant groups barely adsorb CO2 at room temperature, which implies that the pendant doors of the MOFs should have an appropriate length for selective CO2 capture.
Copper(II)‐Mediated Self‐Assembly of Hairpin Peptides and Templated Synthesis of CuS Nanowires
Authors: Wang Chengdong , Sun Yawei , Wang Jiqian , Xu Hai , Lu Jian R. 
Published: June 2015

AbstractThe self‐assembly of peptides and proteins under well‐controlled conditions underlies important nanostructuring processes that could be harnessed in practical applications. Herein, the synthesis of a new hairpin peptide containing four histidine residues is reported and the self‐assembly process mediated by metal ions is explored. The work involves the combined use of circular dichroism, NMR spectroscopy, UV/Vis spectroscopy, AFM, and TEM to follow the structural and morphological details of the metal‐coordination‐mediated folding and self‐assembly of the peptide. The results indicate that by forming a tetragonal coordination geometry with four histidine residues, copper(II) ions selectively trigger the peptide to fold and then self‐assemble into nanofibrils. Furthermore, the copper(II)‐bound nanofibrils template the synthesis of CuS nanowires, which display a near‐infrared laser‐induced thermal effect.
Indolizino[5,6‐b]quinoxaline Derivatives: Intramolecular Charge Transfer Characters and NIR Fluorescence
Authors: Kojima Mitsuru , Hayashi Hironobu , Aotake Tatsuya , Ikeda Shinya , Suzuki Mitsuharu , Aratani Naoki , Kuzuhara Daiki , Yamada Hiroko 
Published: June 2015

AbstractIndolizino[5,6‐b]quinoxaline derivatives (1 a and 1 b) with a push–pull structure were prepared to show intramolecular charge‐transfer properties. Compounds 1 a and 1 b are strongly fluorescent in aprotic solvents while symmetrical derivatives (2 a and 2 b) were non‐fluorescent. The π‐expanded α–α linked dimer (10) of indolizino[5,6‐b]quinoxaline 1 b was serendipitously obtained to show NIR absorption over 800 nm and the fluorescence edge reached to 1400 nm.
Findings from the National Birth Defects Prevention Study: Interpretation and translation for the clinician
Authors: Alwan Sura , Chambers Christina D. 
Published: June 2015

BackgroundThe National Birth Defects Prevention Study (NBDPS) is a large U.S. multi‐site case–control study first established in 1996 to identify potentially preventable environmental causes and genetic risk factors for more than 30 selected categories of major birth defects.MethodsNumerous reports with both positive and negative findings have been produced by the NBDPS, and many have influenced clinical practice. Many NBDPS reports have included novel findings, and in some cases these findings could only be considered hypothesis‐generating. Other reports have met criteria for causality such as replication of findings in other studies, biological plausibility, and coherence.ResultsHowever, translation of even strongly supported associations, in some cases, has required clinicians to learn to communicate information to patients about small and uncertain absolute risks in the context of the potential effects of under‐ or poorly treated maternal conditions.ConclusionThe NBDPS has continued to play an important role as a rich U.S. data source that can advance the understanding of maternal conditions and their treatments in relation to birth defects. Birth Defects Research (Part A) 103:721–728, 2015. © 2015 Wiley Periodicals, Inc.
Antimicrobial mechanism of resveratrol‐trans‐dihydrodimer produced from peroxidase‐catalyzed oxidation of resveratrol
Authors: Mora‐Pale Mauricio , Bhan Namita , Masuko Sayaka , James Paul , Wood Julia , McCallum Scott , Linhardt Robert J. , Dordick Jonathan S. , Koffas Mattheos A. G. 
Published: June 2015

ABSTRACTPlant polyphenols are known to have varying antimicrobial potencies, including direct antibacterial activity, synergism with antibiotics and suppression of bacterial virulence. We performed the in vitro oligomerization of resveratrol catalyzed by soybean peroxidase, and the two isomers (resveratrol‐trans‐dihydrodimer and pallidol) produced were tested for antimicrobial activity. The resveratrol‐trans‐dihydrodimer displayed antimicrobial activity against the Gram‐positive bacteria Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus (minimum inhibitory concentration (MIC) = 15.0, 125, and 62.0 μM, respectively) and against Gram‐negative Escherichia coli (MIC = 123 μM, upon addition of the efflux pump inhibitor Phe‐Arg‐β‐naphthylamide). In contrast, pallidol had no observable antimicrobial activity against all tested strains. Transcriptomic analysis implied downregulation of ABC transporters, genes involved in cell division and DNA binding proteins. Flow cytometric analysis of treated cells revealed a rapid collapse in membrane potential and a substantial decrease in total DNA content. The active dimer showed >90% inhibition of DNA gyrase activity, in vitro, by blocking the ATP binding site of the enzyme. We thus propose that the resveratrol‐trans‐dihydrodimer acts to: (1) disrupt membrane potential; and (2) inhibit DNA synthesis. In summary, we introduce the mechanisms of action and the initial evaluation of an active bactericide, and a platform for the development of polyphenolic antimicrobials. Biotechnol. Bioeng. 2015;112: 2417–2428. © 2015 Wiley Periodicals, Inc.