bluuebunny/crossref_metadata_2025_split huggingface dataset:
Constraining dolomitization by Mg isotopes: A case study from partially dolomitized limestones of the middle Cambrian Xuzhuang Formation, North China
Authors: Peng Yang , Shen Bing , Lang Xian‐Guo , Huang Kang‐Jun , Chen Ji‐Tao , Yan Zhen , Tang Wen‐bo , Ke Shan , Ma Hao‐Ran , Li Fang‐Bing 
Published: February 2016

AbstractThe “dolomite problem” refers to the rare dolomite formation in modern oceans that is in sharp contrast to the widespread ancient dolostone in rock record, as well as failure of laboratory inorganic dolomite precipitation at near Earth‐surface temperature. Novel Mg isotope systematics provides a promising tool in resolving the “dolomite problem”. Here, we develop a protocol to place constraints on the dolomitization process by using Mg isotopes. In this study, we measured Mg isotopic compositions (
) of two batches of partially dolomitized limestone samples from the middle Cambrian Xuzhuang Formation in North China.
varies between −0.55‰ and −3.18‰, and shows a negative linear correlation with
, suggesting that
can be described by a binary mixing between the calcite and dolomite components. Mg isotopic composition of the dolomite component (
) for the lower sample set that is collected from a 4 m stratigraphic interval containing three high‐frequency ribbon rock‐packstone cycles is −1.6‰, while
for the upper sample set (from a thick sequence of ribbon rock) is significantly higher (−0.3‰). However, neither mineralogical and elemental compositions, carbon and oxygen isotopes, nor crystal morphologies of dolomite provides diagnostic criteria to differentiate these two batches of samples.
of the Xuzhuang limestone is simulated by the Advective Flow (AF) and the Diffusion‐Advection‐Reaction (DAR) models. The AF model assumes that Mg is transported by advective fluid flows, while the DAR model simulates a contemporaneous seawater dolomitization process, in which Mg is delivered by diffusion. The AF modeling result indicates that
of the dolomitization fluid is +0.4‰ and +1.7‰ for the lower and upper sample sets, respectively. These values are significantly higher than modern and Cenozoic seawater Mg isotopic composition, suggesting that the dolomitization fluid is not contemporaneous seawater. The AF model also predicts spatially heterogeneous
with progressive enrichment in 26Mg along the fluid flow pathway. In the DAR model, both dolomite content and
of the lower sample set can be simulated by using seawater Mg isotopic composition of −0.75‰, thus contemporaneous seawater dolomitization may explain
of the Xuzhuang limestone. Furthermore, the DAR model demonstrates spatially homogeneous
. To differentiate the AF and DAR models, samples from multiple sections are required. Nevertheless, this study implies that Mg isotope might be a useful tool in the study of dolomitization.
Solar wind drivers of energetic electron precipitation
Authors: Asikainen T. , Ruopsa M. 
Published: February 2016

AbstractDisturbances of near‐Earth space are predominantly driven by coronal mass ejections (CMEs) mostly originating from sunspots and high‐speed solar wind streams (HSSs) emanating from coronal holes. Here we study the relative importance of CMEs and HSSs as well as slow solar wind in producing energetic electron precipitation. We use the recently corrected energetic electron measurements from the Medium Energy Proton Electron Detector instrument on board low‐altitude NOAA/Polar Orbiting Environmental Satellites from 1979 to 2013. Using solar wind observations categorized into three different flow types, we study the contributions of these flows to annual electron precipitation and their efficiencies in producing precipitation. We find that HSS contribution nearly always dominates over the other flows and peaks strongly in the declining solar cycle phase. CME contribution mostly follows the sunspot cycle but is enhanced also in the declining phase. The efficiency of both HSS and CME peaks in the declining phase. We also study the dependence of electron precipitation on solar wind southward magnetic field component, speed, and density and find that the solar wind speed is the dominant factor affecting the precipitation. Since HSSs enhance the average solar wind speed in the declining phase, they also enhance the efficiency of CMEs during these times and thus have a double effect in enhancing energetic electron precipitation.
Replacement of multiyear sea ice and changes in the open water season duration in the Beaufort Sea since 2004
Authors: Galley R. J. , Babb D. , Ogi M. , Else B. G. T. , Geilfus N.‐X. , Crabeck O. , Barber D. G. , Rysgaard S. 
Published: February 2016

AbstractThe last decade has witnessed the nine lowest Arctic September sea ice extents in the observational record. It also forms the most recent third of the long‐term trend in that record, which reached −13.4% decade−1 in 2015. While hemispheric analyses paint a compelling picture of sea ice loss across the Arctic, the situation with multiyear ice in the Beaufort Sea is particularly dire. This study was undertaken in light of substantial changes that have occurred in the extent of summer multiyear sea ice in the Arctic inferred from the passive microwave record. To better elucidate these changes at a sub‐regional scale, we use data from the Canadian Ice Service archive, the most direct observations of sea ice stage‐of‐development available. We also build upon the only previous sea ice climatological analysis for Canada's western Arctic region by sea ice stage‐of‐development that ended in 2004. The annual evolution of sea ice by stage of development in Canada's western Arctic changed dramatically between 1983 and 2014. The rate of these changes and their spatial prevalence were most prominent in the last decade. In summer, total sea ice loss occurred via reductions in old and first‐year sea ice over increasingly large areas and over more months per year. Resultant delay of thermodynamic freeze up has increased the annual open water duration in the study region. The winter sea ice cover was increasingly composed of first‐year sea ice at the expense of old ice. Breakup timing has not significantly changed in the region.
The vulnerability and resilience of a city's water footprint: The case of Flagstaff, Arizona, USA
Authors: Rushforth Richard R. , Ruddell Benjamin L. 
Published: February 2016

AbstractResearch has yet to operationalize water footprint information for urban water policy and planning to reduce vulnerability and increase resilience to water scarcity. Using a county‐level database of the U.S. hydro‐economy, NWED, we spatially mapped and analyzed the Water Footprint of Flagstaff, Arizona, a small city. Virtual water inflow and outflow networks were developed using the flow of commodities into and out of the city. The power law distribution of virtual water trade volume between Flagstaff and its county trading partners broke at a spatial distance of roughly 2000 km. Most large trading partners are within this geographical distance, and this distance is an objective definition for Flagstaff's zone of indirect hydro‐economic influence—that is, its water resource hinterland. Metrics were developed to measure Flagstaff's reliance on virtual water resources, versus direct use of local physical water resources. Flagstaff's reliance on external water supplies via virtual water trade increases both its hydro‐economic resilience and vulnerability to water scarcity. These methods empower city managers to operationalize the city's Water Footprint information to reduce vulnerability, increase resilience, and optimally balance the allocation of local physical water supplies with the outsourcing of some water uses via the virtual water supply chain.
Unexpected high 35S concentration revealing strong downward transport of stratospheric air during the monsoon transitional period in East Asia
Authors: Lin Mang , Zhang Zhisheng , Su Lin , Su Binbin , Liu Lanzhong , Tao Jun , Fung Jimmy C. H. , Thiemens Mark H. 
Published: February 2016

AbstractOctober is the monsoon transitional period in East Asia (EA) involving a series of synoptic activities that may enhance the downward transport of stratospheric air to the planetary boundary layer (PBL). Here we use cosmogenic 35S in sulfate aerosols (35SO42−) as a tracer for air masses originating from the stratosphere and transported downward to quantify these mixing processes. From 1 year 35SO42− measurements (March 2014 to February 2015) at a background station in EA we find remarkably enhanced 35SO42− concentration (3150 atoms m−3) in October, the highest value ever reported for natural sulfate aerosols. A four‐box 1‐D model and meteorological analysis reveal that strong downward transport from the free troposphere is a vital process entraining aged stratospheric air masses to the PBL. The aged stratospheric masses are accumulated in the PBL, accelerating the SO2 transformation to SO42−. Implications for the tropospheric O3 budget and the CO2 biogeochemical cycle are discussed.
High‐throughput sequencing of immune repertoires in multiple sclerosis
Authors: Lossius Andreas , Johansen Jorunn N. , Vartdal Frode , Holmøy Trygve 
Published: February 2016

AbstractT cells and B cells are crucial in the initiation and maintenance of multiple sclerosis (MS), and the activation of these cells is believed to be mediated through specific recognition of antigens by the T‐ and B‐cell receptors. The antigen receptors are highly polymorphic due to recombination (T‐ and B‐cell receptors) and mutation (B‐cell receptors) of the encoding genes, which can therefore be used as fingerprints to track individual T‐ and B‐cell clones. Such studies can shed light on mechanisms driving the immune responses and provide new insights into the pathogenesis. Here, we summarize studies that have explored the T‐ and B‐cell receptor repertoires using earlier methodological approaches, and we focus on how high‐throughput sequencing has provided new knowledge by surveying the immune repertoires in MS in even greater detail and with unprecedented depth.
Enantiodivergent Brucine Diol‐Catalyzed 1,3‐Dipolar Cycloaddition of Azomethine Ylides with α,β‐Unsaturated Ketones
Authors: Li Jian‐Yuan , Kim Hun Young , Oh Kyungsoo 
Published: February 2016

AbstractEnantiodivergent catalyst systems were developed using metals with different ionic radii and a multifunctional brucine diol (BD) ligand. The catalytic use of purported 1:1 Cu‐BD complexes in the 1,3‐dipolar cycloaddition of azomethine ylides with chalcones resulted in the selective formation of endo‐pyrrolidines in 87–96% ees with an absolute stereochemical outcome of (2R,3S,4R,5S). In contrast, an opposite absolute stereochemical outcome was observed by using the catalysts derived from Ag(I) salts and BD. The demonstration of enantiodivergent approaches to a broad class of substrates/reaction types underlines their synthetic value in asymmetric synthesis.magnified image
Effect of Graphite Oxide Dispersion Evaluated with Multifractal on Mechanical Properties and Thermal Stability of Poly(3hydroxybutyrate‐co‐4hydroxybutyrate)/Graphite Oxide Biocomposites
Authors: Yang Jia , Wang Yuli , Chen Qiang , Qin Gang , Liu Shuzheng 
Published: February 2016

ABSTRACTPoly(3hydroxybutyrate‐co‐4hydroxybutyrate) [P(3HB‐co‐4HB)]/graphite oxide (GO) composites were fabricated using a solution mixing method. The GO structures in the composites were analyzed by using transmission electron microscopy, Raman spectroscopy, and X‐ray diffraction. The fracture morphology of the samples was evaluated by the multifractal, and the effect of GO dispersion on the mechanical properties and the thermal stability were discussed for the P(3HB‐co‐4HB) and the composites. It was found that the interlayer spacing of the GO increased due to the intercalation of the polymer into the GO platelets. As the GO content increased, the relative multifractal spectrum increased, but the mechanical properties declined for the composites, indicating that the filler agglomeration effect overcame the reinforcement benefits for the high loadings of the GO. Moreover, both good dispersion and high content of the GO platelets increased the thermal stability of the composites. Therefore, the relative multifractal spectrum width of the fracture morphology was related to the mechanical properties and the thermal stability of the composites.
Piperidine‐Catalyzed 1,3‐Dipolar Cycloaddition of Diazoesters to Enones
Authors: Huang Jiayao , Wu Minghu , Hu Liqiang , Guo Haibin , Sun Shaofa 
Published: February 2016

AbstractAn organocatalytic 1,3‐dipolar cycloaddition of diazoesters to enones has been developed. The reaction is catalyzed by a secondary amine to give substituted pyrazoles in high yields and excellent regioselectivity.
Total Synthesis of Coibacin D by Using Enantioselective Allylation and Metathesis Reactions
Authors: Kolská Kristýna , Ghavre Mukund , Pour Milan , Hybelbauerová Simona , Kotora Martin 
Published: February 2016

AbstractThe first asymmetric total synthesis of coibacin D, a metabolite isolated from the marine cyanobacterium cf. Oscillatoria sp., was achieved in six steps starting from simple hept‐6‐en‐1‐ol. The synthetic strategy was based on a chiral Brønsted acid catalyzed enantioselective allylboration and a Ru‐carbene complex catalyzed sequential ring‐closing and cross‐metathesis strategy. The recorded spectroscopic data and the sign of the optical rotation of the synthesized coibacin D were in agreement with the published data for the isolated compound, which confirmed the proposed structure and absolute configuration.
Ethnicity influences disease characteristics and symptom severity in allergic rhinitis patients in Malaysia
Authors: Amini Peyman , Abdullah Maha , Seng Lee Sing , Karunakaran Thanusha , Hani Norzhafarina , Bakar Saraiza Abu , Latiff Amir Hamzah Abdul , Fong Seow Heng , Yeow Yap Yoke 
Published: February 2016

BackgroundThe number of available reports regarding the influence of ethnicity on clinical features of allergic rhinitis (AR), especially disease severity in tropical climates, is limited. We aimed to compare clinical parameters and disease severity in AR patients of different ethnicities.MethodsMalay, Chinese, and Indian AR patients (n = 138) with confirmed sensitivity to Dermatophagoides pteronyssinus, Dematophagoides farinae, and Blomia tropicalis were tested for mite‐specific immunoglobulin E (sIgE) levels. A detailed questionnaire was used to collect data on nasal symptom score (NSS), ocular symptom score (OSS), sum of symptoms score (SSS), quality of life score (QLS), symptomatic control score (SCS), and total sum of scores (TSS) and correlate the derived data with patients’ demography, mite‐polysensitivity, and sIgE levels.ResultsAR‐related symptoms were most severe in Malays and least in Chinese (p < 0.01). Age (r = 0.516 to 0.673, p < 0.05) and duration of AR (r = 0.635 to 0.726, p < 0.01) correlated positively with severity domains (NSS, SSS, QLS, and TSS) in Chinese. Duration of concurrent allergies was highest in Malays (p < 0.05). Polysensitivity predicted increased sIgE levels in Malays (r = 0.464 to 0.551, p < 0.01) and Indians (r = 0.541 to 0.645, p < 0.05) but affected NSS, SSS, and TSS only in Indians (r = 0.216 to 0.376, p < 0.05). sIgE levels were lowest among Chinese but correlated strongly with NSS, OSS, SSS, and TSS (r = 0408 to 0.898, p < 0.05).ConclusionClinical parameters in AR may be influenced by race. Symptoms were most severe among Malays but did not correlate with other variables examined. Although Indian ethnicity did not impact disease severity, duration of concurrent allergies and mite‐polysensitivity was associated with more severe disease. Age, duration of disease, and sIgE levels may be useful indicators of disease severity in Chinese.
Orthogonale Assemblierung von Proteinen auf DNA‐Nanostrukturen mithilfe von Relaxasen
Authors: Sagredo Sandra , Pirzer Tobias , Aghebat Rafat Ali , Goetzfried Marisa A. , Moncalian Gabriel , Simmel Friedrich C. , de la Cruz Fernando 
Published: February 2016

AbstractDNA‐bindende Proteine erlauben die sequenzspezifische Modifikation von DNA‐basierten Nanostrukturen. Hier untersuchen wir die Eignung von Relaxaseproteinen – speziell TrwC, TraI und MobA – für die Nanofabrikation. Relaxasen sind Komponenten des bakteriellen Konjugationsmechanismus, bei dem Plasmide zwischen Bakterien ausgetauscht werden, wobei sie an DNA durch eine kovalente Phosphotyrosinbindung binden. Wir untersuchen die Anbindung der Relaxasen an zwei prototypische DNA‐Origamistrukturen – stabförmige Sechs‐Helix‐Bündel und flache rechteckige Origami‐Platten. Die Proteine zeigen orthogonale Anbindungseigenschaften mit Ausbeuten von 40–50 % pro Bindestelle, vergleichbar mit alternativen Funktionalisierungsmethoden. Die Ausbeuten variieren zwischen den Origamistrukturen und hängen auch von der Position der Bindestellen ab. Aufgrund ihrer Spezifität für einzelsträngige Zielsequenzen und ihrer orthogonalen Anbindeeigenschaften sind Relaxasen eine einzigartige Erweiterung des molekularen Werkzeugkastens für die Modifikation von DNA‐Nanostrukturen.
Kristallstruktur‐geleitetes Design selbstorganisierender RNA‐Nanodreiecke
Authors: Boerneke Mark A. , Dibrov Sergey M. , Hermann Thomas 
Published: February 2016

AbstractRNA‐Nanotechnologie nutzt RNA‐Strukturmotive zur Konstruktion von Molekülarchitekturen im Nanomaßstab, die sich durch selektive Basenpaar‐Wechselwirkungen selbstorganisieren. Hier berichten wir über Kristallstruktur‐geleitetes Design von stabilen RNA‐Nanodreiecken, die sich durch Selbstorganisation aus kurzen Oligonukleotiden bilden. Eine Kristallstrukturbestimmung eines Nanodreiecks von 81 Nukleotiden mit 2.6 Å Auflösung zeigt das bisher kleinste in sich geschlossene Nanoobjekt, das vollständig aus doppelsträngiger RNA besteht. Da die Eckbausteine des Nanodreiecks Ligand‐bindende RNA‐Schalter enthalten, ergibt sich die Möglichkeit, die Selbstorganisation und Dissoziation durch externe Liganden zu kontrollieren.
Krypton Derivatization of an O2‐Tolerant Membrane‐Bound [NiFe] Hydrogenase Reveals a Hydrophobic Tunnel Network for Gas Transport
Authors: Kalms Jacqueline , Schmidt Andrea , Frielingsdorf Stefan , van der Linden Peter , von Stetten David , Lenz Oliver , Carpentier Philippe , Scheerer Patrick 
Published: February 2016

Abstract[NiFe] hydrogenases are metalloenzymes catalyzing the reversible heterolytic cleavage of hydrogen into protons and electrons. Gas tunnels make the deeply buried active site accessible to substrates and inhibitors. Understanding the architecture and function of the tunnels is pivotal to modulating the feature of O2 tolerance in a subgroup of these [NiFe] hydrogenases, as they are interesting for developments in renewable energy technologies. Here we describe the crystal structure of the O2‐tolerant membrane‐bound [NiFe] hydrogenase of Ralstonia eutropha (ReMBH), using krypton‐pressurized crystals. The positions of the krypton atoms allow a comprehensive description of the tunnel network within the enzyme. A detailed overview of tunnel sizes, lengths, and routes is presented from tunnel calculations. A comparison of the ReMBH tunnel characteristics with crystal structures of other O2‐tolerant and O2‐sensitive [NiFe] hydrogenases revealed considerable differences in tunnel size and quantity between the two groups, which might be related to the striking feature of O2 tolerance.
Orthogonal Protein Assembly on DNA Nanostructures Using Relaxases
Authors: Sagredo Sandra , Pirzer Tobias , Aghebat Rafat Ali , Goetzfried Marisa A. , Moncalian Gabriel , Simmel Friedrich C. , de la Cruz Fernando 
Published: February 2016

AbstractDNA‐binding proteins are promising reagents for the sequence‐specific modification of DNA‐based nanostructures. Here, we investigate the utility of a series of relaxase proteins—TrwC, TraI, and MobA—for nanofunctionalization. Relaxases are involved in the conjugative transfer of plasmids between bacteria, and bind to their DNA target sites via a covalent phosphotyrosine linkage. We study the binding of the relaxases to two standard DNA origami structures—rodlike six‐helix bundles and flat rectangular origami sheets. We find highly orthogonal binding of the proteins with binding yields of 40–50 % per binding site, which is comparable to other functionalization methods. The yields differ for the two origami structures and also depend on the position of the binding sites. Due to their specificity for a single‐stranded DNA target, their orthogonality, and their binding properties, relaxases are a uniquely useful addition to the toolbox available for the modification of DNA nanostructures with proteins.
Oxide‐Modified Nickel Photocatalysts for the Production of Hydrocarbons in Visible Light
Authors: Zhao Yufei , Zhao Bo , Liu Jinjia , Chen Guangbo , Gao Rui , Yao Siyu , Li Mengzhu , Zhang Qinghua , Gu Lin , Xie Jinglin , Wen Xiaodong , Wu Li‐Zhu , Tung Chen‐Ho , Ma Ding , Zhang Tierui 
Published: February 2016

AbstractMetallic nickel nanostructures that were partially decorated by discrete nickel oxide layers were fabricated by in situ reduction of calcinated Ni‐containing layered double hydroxide nanosheets, the structure of which was confirmed by extended X‐ray absorption fine structure spectroscopy, X‐ray photoelectron spectroscopy, and transmission electron microscopy. The existence of the abundant interfaces between the surface Ni oxide overlayer and metallic Ni altered the geometric/electronic structure of the Ni nanoparticles, making them apt for CO activation under light irradiation. Most importantly, the unique structure favors the C−C coupling reaction on its surface, which confers the catalyst unexpected reaction power towards higher hydrocarbons at moderate reaction conditions. This study leads to a green and sustainable approach for the photocatalytic production of highly valuable chemical fuels.
Identification of microsatellite loci and examination of genetic structure for the endangered springsnails Juturnia kosteri and Pyrgulopsis roswellensis in the Chihuahuan Desert
Authors: Holste Danielle R. , Inoue Kentaro , Lang Brian K. , Berg David J. 
Published: February 2016

Abstract

Desert spring ecosystems harbour many endemic species that are threatened with extinction owing to human activities. Springsnails (superfamily Truncatelloidea) are among the most diverse freshwater snail groups in desert springs of western North America. They occupy geographically narrow ranges, often consisting of a single spring or spring complex.
Microsatellite markers were developed via high‐throughput de novo sequencing for two endangered springsnail species, Juturnia kosteri and Pyrgulopsis roswellensis, endemic to springs on Bitter Lake National Wildlife Refuge (BLNWR) near Roswell, New Mexico, USA. Genetic diversity, population structure, effective population size (Ne), and historic demography were assessed in two populations for each species.
A large number of putative markers were identified, of which 14 loci for J. kosteri and 18 loci for P. roswellensis showed polymorphism. Genetic diversity and Ne were greater in P. roswellensis than J. kosteri. Significant genetic differentiation (FST = 0.187–0.288) was found among populations for both species, indicating currently limited gene flow. Neither species showed signs of recent population bottlenecks.
Analyses with microsatellite markers revealed fine‐scale population genetic structure in both species, unlike a previous study using mitochondrial DNA sequences. Although these species co‐occur on BLNWR, slightly different genetic characteristics between them suggest that they may have different evolutionary and demographic histories. Small Ne relative to census size indicates strong genetic drift in these populations. Future efforts should be directed to identifying causes of such strong drift.
Because there are limited numbers of microsatellite markers available for springsnails, the markers identified in this study should be useful for congeners via cross‐species amplification. Understanding current genetic variation and structure of these species is not only required for species recovery, but will also be useful for comparisons among many aquatic organisms endemic to springs of western North America.
Copyright © 2016 John Wiley & Sons, Ltd.