bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulse Radiolysis and Ultra‐High‐Performance Liquid Chromatography/High‐Resolution Mass Spectrometry Studies on the Reactions of the Carbonate Radical with Vitamin B12 Derivatives
Authors: Dassanayake Rohan S. , Shelley Jacob T. , Cabelli Diane E. , Brasch Nicola E. 
Published: March 2015

AbstractThe reactions of the carbonate radical anion (CO3.−) with vitamin B12 derivatives were studied by pulse radiolysis. The carbonate radical anion directly oxidizes the metal center of cob(II)alamin quantitively to give hydroxycobalamin, with a bimolecular rate constant of 2.0×109 M−1 s−1. The reaction of CO3.− with hydroxycobalamin proceeds in two steps. The second‐order rate constant for the first reaction is 4.3×108 M−1 s−1. The rate of the second reaction is independent of the hydroxycobalamin concentration and is approximately 3.0×103 s−1. Evidence for formation of corrinoid complexes differing from cobalamin by the abstraction of two or four hydrogen atoms from the corrin macrocycle and lactone ring formation has been obtained by ultra‐high‐performance liquid chromatography/high‐resolution mass spectrometry (UHPLC/HRMS). A mechanism is proposed in which abstraction of a hydrogen atom by CO3.− from a carbon atom not involved in the π conjugation system of the corrin occurs in the first step, resulting in formation of a CoIII C‐centered radical that undergoes rapid intramolecular electron transfer to form the corresponding CoII carbocation complex for about 50 % of these complexes. Subsequent competing pathways lead to formation of corrinoid complexes with two fewer hydrogen atoms and lactone derivatives of B12. Our results demonstrate the potential of UHPLC combined with HRMS in the separation and identification of tetrapyrrole macrocycles with minor modifications from their parent molecule.
Synthesis, Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons
Authors: Riobé François , Szűcs Rózsa , Bouit Pierre‐Antoine , Tondelier Denis , Geffroy Bernard , Aparicio Fátima , Buendía Julia , Sánchez Luis , Réau Régis , Nyulászi László , Hissler Muriel 
Published: March 2015

AbstractWe describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).
Highly Active, Chemo‐ and Regioselective YbII and SmII Catalysts for the Hydrophosphination of Styrene with Phenylphosphine
Authors: Basalov Ivan V. , Dorcet Vincent , Fukin Georgy K. , Carpentier Jean‐François , Sarazin Yann , Trifonov Alexander A. 
Published: March 2015

AbstractStable heteroleptic amido YbII and SmII complexes bearing aminoether–phenolate ligands and devoid of coordinated solvent have been structurally characterized. They afford highly active, chemoselective and, in the case of monoadditions, 100 % anti‐Markovnikov regiospecific catalysts (down to 0.04 mol % loading) for the hydrophosphination of styrene with PhPH2 under mild conditions.
Intermolecular Asymmetric Carboesterification of Alkenes by Using Chiral Amine Auxiliaries under O2: Synthesis of Enantioenriched α‐Methylene‐γ‐Lactones through Chloropalladation of Alkynes
Authors: Zhang Zhenming , Wu Wanqing , Liao Jianhua , Li Jianxiao , Jiang Huanfeng 
Published: March 2015

AbstractHerein, the first example of chloropalladation‐initiated asymmetric intermolecular carboesterification of alkenes with alkynes by using chiral amine auxiliaries is reported. The use of (1S,2S)‐N1,N1‐dimethylcyclohexane‐1,2‐diamine auxiliaries is essential for providing α‐methylene‐γ‐lactones products in moderate to high yields and excellent enantioselectivities at room temperature. Moreover, the chiral amine auxiliaries can be readily removed by hydrolysis during the reaction process to keep the absolute configuration. This oxygen‐ and water‐promoted asymmetric reaction opens a new window to study asymmetric processes in halopalladation reactions.
Diastereoselectively Switchable Asymmetric Haloaminocyclization for the Synthesis of Cyclic Sulfamates
Authors: Cai Yunfei , Zhou Pengfei , Liu Xiaohua , Zhao Jiannan , Lin Lili , Feng Xiaoming 
Published: March 2015

AbstractAn asymmetric synthesis of cyclic sulfamates by catalytic haloaminocyclization of primary sulfamate ester derivatives is described. The remarkable reversal of diastereoselectivity was found to be dependent on the halogen source and the chiral catalyst. By using privileged complexes of N,N′‐dioxides with Sc(OTf)3 or Lu(OTf)3 as the catalyst, a variety of enantioenriched syn‐ and anti‐cyclic sulfamates or related trans‐aziridines could be obtained in 92–99 % ee and up to 97 % yield.
A Photoinduced Cyclization Cascade—Total Synthesis of (−)‐Leuconoxine
Authors: Pfaffenbach Magnus , Gaich Tanja 
Published: March 2015

AbstractA protecting‐group‐free and enantioselective total synthesis of the monoterpenoid indole alkaloid (−)‐leuconoxine was accomplished. The key step comprises a novel photoinduced domino macrocyclization/transannular cyclization involving the Witkop cyclization, for which additional mechanistic evidence is provided. This process furnishes a diaza[5.5.6.6]fenestrane skeleton, which is a hitherto unprecedented structure element.
Suppression of Problematic Compound Oligomerization by Cosolubilization of Nondetergent Sulfobetaines
Authors: Mizukoshi Yumiko , Takeuchi Koh , Arutaki Misa , Takizawa Takeshi , Hanzawa Hiroyuki , Takahashi Hideo , Shimada Ichio 
Published: March 2015

AbstractNumerous small organic compounds exist in equilibrium among monomers, soluble oligomers, and insoluble aggregates in aqueous solution. Compound aggregation is a major reason for false positives in drug screening, and even soluble oligomers can interfere with structural and biochemical analyses. However, an efficient way to manage the equilibrium of aggregation‐prone compounds, especially those involved with soluble oligomers, has not been established. In this study, solution NMR spectroscopy was used as a suitable technique to detect compound oligomers in equilibrium, and it was demonstrated that cosolubilization of nondetergent sulfobetaines (NDSBs) can largely suppress compound oligomerization and aggregation by shifting the equilibrium toward the monomers. The rotational correlation time was obtained from the ratio of the selective and nonselective longitudinal NMR relaxation times, which directly and quantitatively reflected the apparent sizes of the compounds in the equilibrium. The rotational correlation time of the aggregation‐prone compound SKF86002 (1 mM) was substantially reduced from 0.31 to 0.23 ns by cosolubilization of 100 mM NDSB195. NDSB cosolubilization allowed us to perform successful structural and biochemical experiments with substantially fewer artifacts, which represents a strategy to directly resolve the problematic oligomerization and aggregation of compounds.
Universal Efficiency Improvement in Organic Solar Cells Based on a Poly(3‐hexylthiophene) Donor and an Indene‐C60 Bisadduct Acceptor with Additional Donor Nanowires
Authors: Joe Sung‐yoon , Yim Jong Hyuk , Ryu Shin Young , Ha Na Young , Ahn Yeong Hwan , Park Ji‐Yong , Lee Soonil 
Published: March 2015

AbstractWith poly(3‐hexylthiophene) (P3HT) nanowire (NW) inclusion in active layers (ALs), organic solar cells (OSCs) based on P3HT donor and indene‐C60 bisadduct (ICBA) acceptor showed power conversion efficiency (PCE) improvements for both bulk heterojunction (BHJ)‐ and bilayer (BL)‐structure AL devices. The PCE increase was approximately 14 % for both types of P3HT:ICBA OSCs. However, improvements in short‐circuit current density (Jsc) were about 4.4 and 6.4 % for BHJ‐ and BL‐type AL devices, respectively. A systematic study showed that the addition of P3HT NWs did not result in enhanced internal quantum efficiencies for either type of device. However, the difference in light‐harvesting efficiency was important in accounting for Jsc variations. Interestingly, there was no correlation between Jsc and PCE variations, whereas the open‐circuit voltage (Voc) and fill factor (FF) showed correlations with the PCE. The variation in FF is discussed in terms of Voc and equivalent‐circuit parameters based on a nonideal diode model.
Boosting Properties of 3D Binder‐Free Manganese Oxide Anodes by Preformation of a Solid Electrolyte Interphase
Authors: Zhou Haitao , Wang Xuehang , Sheridan Edel , Chen De 
Published: March 2015

AbstractHuge irreversible capacity loss prevents the successful use of metal oxide anodes in Li‐ion full cells. Here, we focus on the critical prelithiation step and demonstrate the challenge of electrolyte decomposition on a pristine anode in a full cell. Both an electrochemical activation process (54 h) with Li metal and a new electrolytic process (75 min) without Li metal were used to preform complete solid electrolyte interphase (SEI) layers on 3 D binder‐free MnOy‐based anodes. The preformed SEI layers mitigated the electrolyte decomposition effectively and widened the working voltage for the MnOy/LiMn2O4 full cell, which resulted in a big boost of the specific energy to 300 and 200 W h kgcathode−1, largely improved cycling stability, and much higher specific power (4200 W h kgtotal−1) compared to conventional Li‐ion batteries. Detailed characterization, such as cyclic voltammetry, scanning transmission electron microscopy, and FTIR spectroscopy, gives mechanistic insight into SEI preformation. This work provides guidance for the design of anode SEI layers and enables the application of oxides for Li‐ion battery full cells.
Can the Canadian drought code predict low soil moisture anomalies in the mineral soil? An analysis of 15 years of soil moisture data from three forest ecosystems in Eastern Canada
Authors: D'Orangeville Loïc , Houle Daniel , Duchesne Louis , Côté Benoît 
Published: March 2015

AbstractThe Canadian Drought Code (CDC) is an empirical soil‐drying model adapted to high‐latitude forests and commonly used by Canadian fire managers and researchers to predict the water content of the organic soil layer. Better knowledge of the capacity of the CDC to predict the effect of droughts on the water content of the mineral soil could improve our capacity to predict the future response of Canadian boreal forests to future changes in drought frequency and intensity.We tested the capacity of the CDC to predict mineral soil water content (SWC) and droughts against long‐term (14–16 years) daily mineral SWC data from time domain reflectometry probes in multiple stations within three forest ecosystems of Eastern Canada respectively dominated by sugar maple, balsam fir and black spruce. Droughts were defined as SWC values lower than one standard deviation from their historical mean. The drought intensity and frequency of each growing season were computed as the sum of daily SWC departures from normal and the sum of days of drought, respectively.Our results show that the CDC is a reliable predictor of mineral SWC (r = 0.6–0.8), drought frequency (r = 0.5–0.9) and intensity (r = 0.7–0.9) for high‐latitude forest ecosystems of Eastern Canada. Lower correlations were due to the poor accuracy of the model at predicting mild droughts at the sugar maple stand due to the SWC values close to the drought threshold. We detected a higher susceptibility to droughts at the black spruce stand due to a 1‐month‐earlier occurrence of severe droughts. Copyright © 2015 John Wiley & Sons, Ltd.
Diastereoselective Synthesis of Indolindiones by Formal [5+1] Double Michael Cycloaddition to 4‐Cinnamoylpyrrolediones
Authors: Silaichev Pavel S. , Filimonov Valeriy O. , Slepukhin Pavel A. , Rubin Michael , Maslivets Andrey N. 
Published: March 2015

AbstractAn efficient [5+1] double Michael cycloaddition of enolates to 4‐cinnamoylpyrrole‐2,3‐diones was investigated; the reaction allows for the highly diastereoselective assembly of indoline scaffolds with up to three contiguous stereogenic centers.
Effect of laying sequence on egg mercury in captive zebra finches: An interpretation considering individual variation
Authors: Ou Langbo , Varian-Ramos Claire W. , Cristol Daniel A. 
Published: March 2015

Abstract

Bird eggs are used widely as noninvasive bioindicators for environmental mercury availability. Previous studies, however, have found varying relationships between laying sequence and egg mercury concentrations. Some studies have reported that the mercury concentration was higher in first-laid eggs or declined across the laying sequence, whereas in other studies mercury concentration was not related to egg order. Approximately 300 eggs (61 clutches) were collected from captive zebra finches dosed throughout their reproductive lives with methylmercury (0.3 μg/g, 0.6 μg/g, 1.2 μg/g, or 2.4 μg/g wet wt in diet); the total mercury concentration (mean ± standard deviation [SD] dry wt basis) of their eggs was 7.03 ± 1.38 μg/g, 14.15 ± 2.52 μg/g, 26.85 ± 5.85 μg/g, and 49.76 ± 10.37 μg/g, respectively (equivalent to fresh wt egg mercury concentrations of 1.24 μg/g, 2.50 μg/g, 4.74 μg/g, and 8.79 μg/g). The authors observed a significant decrease in the mercury concentration of successive eggs when compared with the first egg and notable variation between clutches within treatments. The mercury level of individual females within and among treatments did not alter this relationship. Based on the results, sampling of a single egg in each clutch from any position in the laying sequence is sufficient for purposes of population risk assessment, but it is not recommended as a proxy for individual female exposure or as an estimate of average mercury level within the clutch. Environ Toxicol Chem 2015;34:1787–1792. © 2015 SETAC
Incorporating variability in point estimates in risk assessment: Bridging the gap between LC50 and population endpoints
Authors: Stark John D. , Vargas Roger I. , Banks John E. 
Published: March 2015

Abstract

Historically, point estimates such as the median lethal concentration (LC50) have been instrumental in assessing risks associated with toxicants to rare or economically important species. In recent years, growing awareness of the shortcomings of this approach has led to an increased focus on analyses using population endpoints. However, risk assessment of pesticides still relies heavily on large amounts of LC50 data amassed over decades in the laboratory. Despite the fact that these data are generally well replicated, little or no attention has been given to the sometime high levels of variability associated with the generation of point estimates. This is especially important in agroecosystems where arthropod predator–prey interactions are often disrupted by the use of pesticides. Using laboratory derived data of 4 economically important species (2 fruit fly pest species and 2 braconid parasitoid species) and matrix based population models, the authors demonstrate in the present study a method for bridging traditional point estimate risk assessments with population outcomes. The results illustrate that even closely related species can show strikingly divergent responses to the same exposures to pesticides. Furthermore, the authors show that using different values within the 95% confidence intervals of LC50 values can result in very different population outcomes, ranging from quick recovery to extinction for both pest and parasitoid species. The authors discuss the implications of these results and emphasize the need to incorporate variability and uncertainty in point estimates for use in risk assessment. Environ Toxicol Chem 2015;34:1683–1688. © 2015 SETAC
Exploration of Daphnia behavioral effect profiles induced by a broad range of toxicants with different modes of action
Authors: Chevalier Julie , Harscoët Elodie , Keller Merlin , Pandard Pascal , Cachot Jérôme , Grote Matthias 
Published: March 2015

Abstract

Behavior is increasingly reported as a sensitive and early indicator of toxicant stress in aquatic organisms. However, the systematic understanding of behavioral effects and comparisons between effect profiles is hampered because the available studies are limited to few chemicals and differ in the exposure conditions and effect parameters examined. The aims of the present study were 1) to explore behavioral responses of Daphnia magna exposed to different toxicants, 2) to compare behavioral effect profiles with regard to chemical modes of action, and 3) to determine the sensitivity and response time of behavioral parameters in a new multi-cell exposure system named Multi-DaphTrack compared with currently utilized tests. Twelve compounds covering different modes of toxic action were selected to sample a wide range of potential effect profiles. Acute standard immobilization tests and 48 h of behavioral tracking were performed in the customized Multi-DaphTrack system and a single-cell commercialized biological early warning system. Contrasting behavioral profiles were observed for average speed (i.e., intensity, time of effect onset, effect duration), but no distinct behavioral profiles could be drawn from the chemical mode of action. Most compounds tested in the Multi-DaphTrack system induced an early and significant average speed increase at concentrations near or below the 10% effective concentration (48 h) of the acute immobilization test, demonstrating that the Multi-DaphTrack system is fast and sensitive. To conclude, behavior endpoints could be used as an alternative or complement to the current acute standard test or chemical analysis for the predictive evaluation of ecotoxic effects of effluents or water bodies. Environ Toxicol Chem 2015;34:1760–1769. © 2015 SETAC
Task‐sensitive reconfiguration of corticocortical 6–20 Hz oscillatory coherence in naturalistic human performance
Authors: Saarinen Timo , Jalava Antti , Kujala Jan , Stevenson Claire , Salmelin Riitta 
Published: March 2015

AbstractElectrophysiological oscillatory coherence between brain regions has been proposed to facilitate functional long‐range connectivity within neurocognitive networks. This notion is supported by intracortical recordings of coherence in singled‐out corticocortical connections in the primate cortex. However, the manner in which this operational principle manifests in the task‐sensitive connectivity that supports human naturalistic performance remains undercharacterized. Here, we demonstrate task‐sensitive reconfiguration of global patterns of coherent connectivity in association with a set of easier and more demanding naturalistic tasks, ranging from picture comparison to speech comprehension and object manipulation. Based on whole‐cortex neuromagnetic recording in healthy behaving individuals, the task‐sensitive component of long‐range corticocortical coherence was mapped at spectrally narrow‐band oscillatory frequencies between 6 and 20 Hz (theta to alpha and low‐beta bands). This data‐driven cortical mapping unveiled markedly distinct and topologically task‐relevant spatiospectral connectivity patterns for the different tasks. The results demonstrate semistable oscillatory states relevant for neurocognitive processing. The present findings decisively link human behavior to corticocortical coherence at oscillatory frequencies that are widely thought to convey long‐range, feedback‐type neural interaction in cortical functional networks. Hum Brain Mapp 36:2455–2469, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc..
Do Health Reforms to Improve Quality Have Long‐Term Effects? Results of a Follow‐Up on a Randomized Policy Experiment in the Philippines
Authors: Quimbo Stella , Wagner Natascha , Florentino Jhiedon , Solon Orville , Peabody John 
Published: March 2015

AbstractWe tracked doctors who had previously participated in a randomized policy experiment in the Philippines. The original experiment involved 30 district hospitals divided equally into one control site and two intervention sites that increased insurance payments (full insurance support for children under 5 years old) or made bonus payments to hospital staff. During the 3 years of the intervention, quality—as measured by clinical performance and value vignettes—improved and was sustained in both intervention sites compared with controls. Five years after the interventions were discontinued, we remeasured the quality of care of the doctors. We found that the intervention sites continued to have significantly higher quality compared with the control sites. The previously documented quality improvement in intervention sites appears to be sustained; moreover, it was subject to a very low (less than 1% per year) rate of decay in quality scores. Copyright © 2015 John Wiley & Sons, Ltd.
Financing Long‐Term Care: Ex Ante, Ex Post or Both?
Authors: COSTA‐FONT Joan , Courbage Christophe , Swartz Katherine 
Published: March 2015

AbstractThis paper attempts to examine the heterogeneity in the public financing of long‐term care (LTC) and the wide‐ranging instruments in place to finance LTC services. We distinguish and classify the institutional responses to the need for LTC financing as ex ante (occurring prior to when the need arises, such as insurance) and ex post (occurring after the need arises, such as public sector and family financing). Then, we examine country‐specific data to ascertain whether the two types of financing are complements or substitutes. Finally, we examine exploratory cross‐national data on public expenditure determinants, specifically economic, demographic and social determinants. We show that although both ex ante and ex post mechanisms exist in all countries with advanced industrial economies and despite the fact that instruments are different across countries, ex ante and ex post instruments are largely substitutes for each other. Expenditure estimates to date indicate that the public financing of LTC is highly sensitive to a country's income, ageing of the population and the availability of informal caregiving. Copyright © 2015 John Wiley & Sons, Ltd.
Age‐related decrease in theta and gamma coherence across dorsal ca1 pyramidale and radiatum layers
Authors: Jacobson Tara K. , Schmidt Brandy , Hinman James R. , Escabí Monty A. , Markus Etan J. 
Published: March 2015

ABSTRACTIn both humans and rodents, aging is linked to impairments in hippocampus dependent learning. Given such deficits, one would expect corresponding changes in hippocampal local field potentials, which represent the integration of multiple inputs onto a given dendritic field within the hippocampus. The current experiment examined coherence of theta and gamma in young and aged rats at sub‐millimeter and millimeter distant locations both within and across layers in CA1 of the dorsal hippocampus. The degree to which different dendritic layers show coherent oscillations indicates the uniformity of the inputs and local circuitry, and may form an important element for processing information. Aged rats had lower coherence in all frequency ranges; this was most marked within a layer as the distance between electrodes increased. Notably, unlike younger rats, in the aged rats coherence was not affected by running on the maze. Furthermore, despite the previously reported effects of cholinergic activation on theta frequency and power, there was no effect of the cholinomimetic physostigmine on coherence. These data indicate an age related fragmentation in hippocampal processing that may underlie some of the observed learning and memory deficits. © 2015 Wiley Periodicals, Inc.