bluuebunny/crossref_metadata_2025_split huggingface dataset:
An intercomparison and validation of satellite‐based surface radiative energy flux estimates over the Arctic
Authors: Riihelä Aku , Key Jeffrey R. , Meirink Jan Fokke , Kuipers Munneke Peter , Palo Timo , Karlsson Karl‐Göran 
Published: April 2017

AbstractAccurate determination of radiative energy fluxes over the Arctic is of crucial importance for understanding atmosphere‐surface interactions, melt and refreezing cycles of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite‐based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative flux estimates from Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1‐degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water Cycle Experiment (GEWEX) surface energy budget, and our own experimental FluxNet / Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg flux estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave flux in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave flux over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer‐based GEWEX and FluxNet‐CLARA flux estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the FluxNet‐CLARA downwelling shortwave flux is shown to be an overestimated cloud optical thickness. The results illustrate that satellite‐based flux estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in flux retrievals.
Big Ship Data: Using vessel measurements to improve estimates of temperature and wind speed on the Great Lakes
Authors: Fries Kevin , Kerkez Branko 
Published: April 2017

AbstractThe sheer size of many water systems challenges the ability of in situ sensor networks to resolve spatiotemporal variability of hydrologic processes. New sources of vastly distributed and mobile measurements are, however, emerging to potentially fill these observational gaps. This paper poses the question: How can nontraditional measurements, such as those made by volunteer ship captains, be used to improve hydrometeorological estimates across large surface water systems? We answer this question through the analysis of one of the largest such data sets: an unprecedented collection of one million unique measurements made by ships on the North American Great Lakes from 2006 to 2014. We introduce a flexible probabilistic framework, which can be used to integrate ship measurements, or other sets of irregular point measurements, into contiguous data sets. The performance of this framework is validated through the development of a new ship‐based spatial data product of water temperature, air temperature, and wind speed across the Great Lakes. An analysis of the final data product suggests that the availability of measurements across the Great Lakes will continue to play a large role in the confidence with which these large surface water systems can be studied and modeled. We discuss how this general and flexible approach can be applied to similar data sets, and how it will be of use to those seeking to merge large collections of measurements with other sources of data, such as physical models or remotely sensed products.
Competition between outer zone electron scattering by plasmaspheric hiss and magnetosonic waves
Authors: Ni Binbin , Hua Man , Zhou Ruoxian , Yi Juan , Fu Song 
Published: April 2017

AbstractWe quantify the electron scattering effects of simultaneous plasmaspheric hiss and magnetosonic waves that occurred in two neighboring time intervals but with distinct wave intensity profiles on 21 August 2013. Their combined scattering is found capable of causing electron distribution variations largely distinguishable from the consequences of individual waves. The net effect of electron diffusion relies strongly on the relative dominance of the two wave intensities, which also controls the relative contribution of each wave mode. In combination, MS waves slow down the hiss‐induced loss of ~100 keV electrons, and hiss efficiently inhibits the electron butterfly distribution caused by MS waves to produce a gradual acceleration process. Our results strongly suggest that comprehensive simulations of the radiation belt electron dynamics should carefully incorporate the combined scattering and complex competition resulting from simultaneous occurrences of various magnetospheric emissions, including, but not limited to, plamaspheric hiss and magnetosonic waves.
Benzannulation of 2‐Alkenylindoles using Aldehydes by Sequential Triple‐Relay Catalysis: A Route to Carbazoles and Carbazole Alkaloids
Authors: Banerjee Ankush , Sahu Samrat , Maji Modhu Sudan 
Published: April 2017

AbstractBenzannulation of 2‐alkenylindoles with readily available aldehydes, under one‐pot sequential triple‐relay‐catalysis, provides an easy access to several structurally unique carbazoles including 2‐ and 3‐alkenylcarbazoles. This protecting group‐free method enabled one‐pot synthesis of alkaloids such as hyellazole and 6‐chlorohyellazole, and the formal syntheses of seven other alkaloids. Construction of the core structure, present in murastifoline A, murrafoline E, and related alkaloids was also demonstrated. Even conjugated 3,3′‐biscarbazoles can also be synthesized by one‐pot, two‐fold sequential triple‐relay catalysis.magnified image
Metal Substitution Modulates the Reactivity and Extends the Reaction Scope of Myoglobin Carbene Transfer Catalysts
Authors: Sreenilayam Gopeekrishnan , Moore Eric J. , Steck Viktoria , Fasan Rudi 
Published: April 2017

AbstractEngineered myoglobins have recently emerged as promising scaffolds for catalyzing carbene‐mediated transformations. In this work, we investigated the effect of altering the metal center and first‐sphere coordination residue on the carbene transfer reactivity of myoglobin. To this end, we first established an efficient protocol for the recombinant expression of myoglobin variants incorporating metalloporphyrins with non‐native metals, including second‐ and third‐row transition metals (ruthenium, rhodium, iridium). Characterization of the cofactor‐substituted myoglobin variants across three different carbene transfer reactions (cyclopropanation, N–H insertion, S–H insertion) revealed a major influence of the nature of the metal center, its oxidation state and first‐sphere coordination environment on the catalytic activity, stereoselectivity, and/or oxygen tolerance of these artificial metalloenzymes. In addition, myoglobin variants incorporating manganese‐ or cobalt‐porphyrins were found capable of catalyzing an intermolecular carbene C–H insertion reaction involving phthalan and ethyl α‐diazoacetate, a reaction not supported by iron‐based myoglobins and previously accessed only using iridium‐based (bio)catalysts. These studies demonstrate how modification of the metalloporphyrin cofactor environment provides a viable and promising strategy to enhance the catalytic properties and extend the reaction scope of myoglobin‐based carbene transfer catalysts.magnified image
Enantioselektive Chemo‐ und Biokatalyse: Partner in der Retrosynthese
Authors: Hönig Moritz , Sondermann Philipp , Turner Nicholas J. , Carreira Erick M. 
Published: April 2017

AbstractIn diesem Aufsatz werden neue Entwicklungen auf den Gebieten der biokatalytischen und chemokatalytischen Synthese diskutiert. Der Beitrag soll als Anleitung für die Verwendung biokatalytischer Methoden in der chemischen Synthese dienen, insbesondere bei retrosynthetischen Überlegungen und Analysen. Die Gliederung dieses Aufsatzes ist nach den Bindungsknüpfungen und ihren jeweiligen synthetischen Methoden strukturiert.
Protein Dimerization on a Phosphonated Calix[6]arene Disc
Authors: Rennie Martin L. , Doolan Aishling M. , Raston Colin L. , Crowley Peter B. 
Published: April 2017

AbstractComplex formation between cationic cytochrome c and the water‐soluble, poly‐anionic p‐phosphonatocalix[6]arene (pclx6) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx6 that acts like glue to mediate a symmetric (C2) protein dimer. The calixarene disc has a diameter of about 1.5 nm and masks about 360 Å2 of protein surface. The key protein–calixarene contacts occur via two linchpin lysines, with additional contacts provided by a small hydrophobic patch. The protein–calixarene supramolecular assemblies were observed in solution by size‐exclusion chromatography with multi‐angle light scattering and NMR spectroscopy. Using isothermal titration calorimetry and NMR data, an apparent Kd in the low micromolar range was determined for the charge‐rich protein–calixarene complex. In contrast to p‐sulfonatocalix[4]arene, the larger pclx6 has a single, well‐defined binding site that mediates the assembly of cytochrome c in solution.
Grain‐Boundary‐Free Super‐Proton Conduction of a Solution‐Processed Prussian‐Blue Nanoparticle Film
Authors: Ono Kenta , Ishizaki Manabu , Kanaizuka Katsuhiko , Togashi Takanari , Yamada Teppei , Kitagawa Hiroshi , Kurihara Masato 
Published: April 2017

AbstractA porous crystal family has been explored as alternatives of Nafion films exhibiting super‐proton conductivities of ≥10−2 S cm−1. Here, the proton‐conduction natures of a solution‐processed film of nanoparticles (NPs) have been studied and compared to those of a Nafion film. A mono‐particle film of Prussian‐blue NPs is spontaneously formed on a self‐assembled monolayer substrate by a one‐step solution process. A low‐temperature heating process of the densely packed, pinhole‐free mono‐particle NP film enables a maximum 105‐fold enhancement of proton conductivity, reaching ca. 10−1 S cm−1. The apparent highest conductivity, compared to previously reported data of the porous crystal family, remains constant against humidity changes by an improved water‐retention ability of the film. In our proposed mechanism, the high‐performing solution‐processed NP film suggests that heating leads to the self‐restoration of hydrogen‐bonding networks throughout their innumerable grain boundaries.
Copper‐Catalyzed Aminothiolation of 1,3‐Dienes via a Dihydrothiazine Intermediate
Authors: Sleet Christopher E. , Tambar Uttam K. 
Published: April 2017

AbstractHeteroatom‐containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3‐dienes is especially attractive. Herein, we describe the development of a regio‐ and diastereoselective 1,4‐aminothiolation of 1,3‐dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol. The reaction proceeds via a tandem hetero‐Diels–Alder cycloaddition of N,N′‐bis(benzenesulfonyl)sulfur diimide with 1,3‐diene followed by copper‐catalyzed Grignard substitution. Mechanistic studies support a copper catalyzed formation of an unprecedented [10‐S‐4] sulfurane that reductively eliminates to afford a 3,6‐dihydrothiazine, which is selectively converted to 1,4‐aminothiols.
Fluorophores for Excited‐State Intramolecular Proton Transfer by an Yttrium Triflate Catalyzed Reaction of Isocyanides with Thiocarboxylic Acids
Authors: Tong Shuo , Zhao Shun , He Qing , Wang Qian , Wang Mei‐Xiang , Zhu Jieping 
Published: April 2017

AbstractDiscovery of new chemical reactivity of a given functional group can often result in innovative synthesis of important chemical entities that possess unprecedented properties. We designed and developed a one‐step synthesis of 5‐amino‐4‐carboxamidothiazoles 1 by an yttrium‐triflate‐catalyzed reaction of thiocarboxylic acids 2 with isocyanides 3. In this reaction, both reactants 2 and 3 deviated from their normal reactivities because of metal coordination. The resulting heterocycles are novel prototypical structures for the double ESIPT process. Some of them were excited by visible light irradiation and emitted fluorescence at the NIR region with large Stokes shift, high quantum yield, and strong solvatochromism.
Cleaving Direct‐Laser‐Written Microstructures on Demand
Authors: Zieger Markus M. , Mueller Patrick , Quick Alexander S. , Wegener Martin , Barner‐Kowollik Christopher 
Published: April 2017

AbstractUsing an advanced functional photoresist we introduce direct‐laser‐written (DLW) 3D microstructures capable of complete degradation on demand. The networks consist exclusively of reversible bonds, formed by irradiation of a phenacyl sulfide linker, giving disulfide bonds in a radical‐free step‐growth polymerization via a reactive thioaldehyde. The bond formation was verified in solution by ESI‐MS. To induce cleavage, dithiothreitol causes a thiol–disulfide exchange, erasing the written structure. The mild cleavage of the disulfide network is highly orthogonal to other, for example, acrylate‐based DLW structures. To emphasize this aspect, DLW structures were prepared incorporating reversible structural elements into a non‐reversible acrylate‐based standard scaffold, confirming subsequent selective cleavage. The high lateral resolution achievable was verified by the preparation of well‐defined line gratings with line separations of down to 300 nm.
Iridium‐Catalyzed Regio‐ and Enantioselective Hydroarylation of Alkenyl Ethers by Olefin Isomerization
Authors: Ebe Yusuke , Onoda Mitsuki , Nishimura Takahiro , Yorimitsu Hideki 
Published: April 2017

AbstractIridium‐catalyzed hydroarylation of alkenyl ethers, such as allylic and homoallylic ethers, by C−H bond activation gave high yields of the corresponding addition products, where the aryl groups were selectively installed at the α‐carbon atom to the alkoxy group. The reaction involves an isomerization of the alkenyl ethers into the corresponding 1‐alkenyl ethers, which then undergo the regio‐ and enantioselective hydroarylation.
Relationship between bridged groups and antioxidant activity for aliphatic diamine bridged hindered phenol in polyolefins
Authors: Li Cuiqin , Sun Peng , Guo Suyue , Zhang Zhiqiu , Wang Jun 
Published: April 2017

ABSTRACTFour aliphatic diamine bridged hindered phenols were successfully synthesized with aliphatic diamine as the bridged group and 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionyl chloride as the material, and their structures were clarified by NMR, Fourier transform infrared spectroscopy, and mass spectrometry. Their performance as antioxidant for polypropylene (PP) and linear low‐density polyethylene (LLDPE) were investigated through the melt flow rate and the oxidation induction time. The thermooxidative stabilities of PP and LLDPE with different aliphatic diamine bridged hindered phenols were assessed by the measurement of the oxidation induction temperature and with long‐term aging testing. The results showed that aliphatic diamine bridged hindered phenols could protect two kinds of polyolefins from thermal oxidative degradation, and the mechanical properties and antioxidant activities of polyolefins stabilized with aliphatic diamine bridged hindered phenols were increased with increasing length of the bridged group for aliphatic diamine bridged hindered phenols at the same concentration of phenolic hydroxyl group. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45095.
The utilization of thermomechanical pulp fibers in WPC: A review
Authors: Mertens Oliver , Gurr Julius , Krause Andreas 
Published: April 2017

ABSTRACTThermomechanical pulp (TMP), among other natural fibers, features characteristics that make it a promising candidate for the utilization in polymer composites. This review is providing an overview on the current state of research on TMP reinforced polymer composites. More than 50 references were reviewed. The cited literature is catalogued according to pretreatments, batch or continuous procedures, processing at laboratory or industrial scale, fiber contents, polymer types, coupling agents as well as wood species. The reinforcing potential of TMP utilized in composites is demonstrated. Tensile strength was found to be peaking at a fiber content of around 40 wt %. Fiber morphology is presumed to be an important determinator for composite properties. Specific mechanical energy [kWh/kg] is presented as an indicator suitable to compare the influence of various processes on fiber morphology. Furthermore, the feed‐in and dosing issue that generally accompanies the utilization of cellulosic fibers is described and possible solutions are discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45161.
Brief Report: Genetic Variation of the α1‐Antitrypsin Gene Is Associated With Increased Autoantibody Production in Rheumatoid Arthritis
Authors: McCarthy Cormac , Orr Carl , Fee Laura T. , Carroll Tomás P. , Dunlea Danielle M. , Hunt David J. L. , Dunne Eimear , O'Connell Paul , McCarthy Geraldine , Kenny Dermot , Fearon Ursula , Veale Douglas J. , Reeves Emer P. , McElvaney Noel G. 
Published: April 2017

ObjectiveTo examine the prevalence of α1‐antitrypsin deficiency (AATD) in rheumatoid arthritis (RA), and to determine whether AATD is associated with higher levels of rheumatoid factor (RF), antinuclear antibodies (ANAs), and anti–citrullinated peptide autoantibodies (ACPAs).MethodsRF, ANAs, and ACPAs were measured by standard immunoturbidimetry, immunofluorescence assay, and enzyme‐linked immunosorbent assay, respectively. Characterization of AAT phenotypes was performed by isoelectric focusing and immunofixation. The chi‐square test with Yates' correction and the Mann‐Whitney U test were used to assess the prevalence of alleles associated with AATD in RA and to compare mean antibody titers, respectively.ResultsOf 246 patients with RA, 24 who were heterozygous for AATD were identified, with no statistically significant difference in the prevalence of AATD between RA patients and the general population (P = 0.39). A positive association between heterozygosity for AATD and the production of ACPAs was observed (P < 0.0001), with increased ACPA titers recorded in the AATD RA cohort compared with the general population (P = 0.01).ConclusionAAT heterozygous status in RA is strongly associated with positive ACPAs and may define a distinct subset of patients with increased disease severity.
Unusual Assembly and Conversion of Graphene Quantum Dots into Crystalline Graphite Nanocapsules
Authors: Gao Jian , Xu Chenyu , Hu Yue , Zhao Fei , Shao Changxiang , Zhao Yang , Chen Shilv , Qu Liangti 
Published: April 2017

AbstractThe development of a facile strategy for conversion of graphene quantum dots (GQDs) into crystalline graphite is of great practical significance and still remains challenging. Herein, rationally assembled crystalline‐intercrossed graphite nanocapsules (CI‐GNCs) have been realized by a one‐step electrochemically induced strategy with the assistance of a soft template, in which the GQDs act as the initial building blocks. The as‐prepared CI‐GNCs exhibit highly crystalline graphitic nanostructures. Moreover, they possess promising electrocatalytic activity for the oxygen reaction reduction (ORR) in alkaline medium. This simple fabrication technology presents a great advance for synthesizing CI‐GNCs composite catalysts, which have potential as new metal‐free catalysts for efficient ORR applications.
Validated UHPLC–MS/MS assay for quantitative determination of etoposide, gemcitabine, vinorelbine and their metabolites in patients with lung cancer
Authors: Gong Xiaobin , Yang Le , Zhang Feng , Liang Youtian , Gao Shouhong , Liu Ke , Chen Wansheng 
Published: April 2017

AbstractA fully valid UHPLC–MS/MS method was developed for the determination of etoposide, gemcitabine, vinorelbine and their metabolites (etoposide catechol, 2′,2′‐difluorodeoxyuridine and 4‐O‐deacetylvinorelbine) in human plasma. The multiple reaction monitoring mode was performed with an electrospray ionization interface operating in both the positive and negative ion modes per compound. The method required only 100 μL plasma with a one‐step simple de‐proteinization procedure, and a short run time of 7.5 min per sample. A Waters ACQUITY UPLC HSS T3 column (2.1 × 100 mm, 1.8 μm) provided chromatographic separation of analytes using a binary mobile phase gradient (A, 0.1% formic acid in acetonitrile, v/v; B, 0.1% formic acid in water, v/v). Linear coefficients of correlation were >0.995 for all analytes. The relative deviation of this method was <10% for intra‐ and inter‐day assays and the accuracy ranged between 86.35% and 113.44%. The mean extraction recovery and matrix effect of all the analytes were 62.07–105.46% and 93.67–105.87%, respectively. This method was successfully applied to clinical samples from patients with lung cancer.
Palladium on Polydopamine: Its True Potential in Catalytic Transfer Hydrogenations and Heck Coupling Reactions
Authors: Kunfi Attila , Szabó Vivien , Mastalir Ágnes , Bucsi Imre , Mohai Miklós , Németh Péter , Bertóti Imre , London Gábor 
Published: April 2017

AbstractThe application of Pd–polydopamine and magnetic Fe3O4@Pd–polydopamine catalysts in catalytic transfer hydrogenation reactions and the Heck arylation is reported. The reduction of a wide range of aromatic nitro‐compounds bearing both electron‐donating and ‐withdrawing substituents to the corresponding anilines could be efficiently performed, although the reduction of carbonyl compounds was found to be less general. In the latter case, only aromatic ketones could be reduced to the corresponding alcohols, whereas aldehyde substrates were unaffected, which may be owing to their reaction with the catalyst support leading to catalyst deactivation. By using magnetic Fe3O4@Pd–polydopamine system, facilitated catalyst recovery and reuse for five consecutive cycles without considerable loss of activity in nitro‐group reduction. The efficiency of the catalyst in Heck reactions was comparable to that in transfer hydrogenation, however, no catalytic activity was observed upon reuse in this case, likely as a result of metal leaching. We also explored tandem Heck reaction/catalytic transfer hydrogenation sequences, however, the two reactions showed limited compatibility under the applied conditions.
Stereoselective and Enantiospecific Mono‐ and Bis‐C−H Azidation of Tröger Bases: Insight on Bridgehead Iminium Intermediates and Application to Anion‐Binding Catalysis
Authors: Bosmani Alessandro , Pujari Sandip A. , Besnard Céline , Guénée Laure , Poblador‐Bahamonde Amalia I. , Lacour Jérôme 
Published: April 2017

AbstractIn the context of Tröger base chemistry, regio‐ and stereoselective Csp3−H azidation reactions are reported. Azide functional groups are introduced at either one or the two benzylic positions selectively. Mild conditions and good yields are afforded by the combination of TMSN3 and iodosobenzene PhIO. The process occurs with high enantiospecificity (es 96–99 %) and—interestingly and importantly—via bridgehead iminium intermediates as shown by mechanistic and in‐silico studies. Finally, mono‐ and bistriazole derivatives were prepared in high yields and enantiospecificity by using copper‐catalyzed alkyne azide cycloaddition (CuAAC) reactions; some of the products were used as anion‐binding organocatalysts for the tritylation of amines and alcohols.