bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intrinsic Artefacts in Optical Oxygen Sensors—How Reliable are our Measurements?
Authors: Lehner Philipp , Staudinger Christoph , Borisov Sergey M. , Regensburger Johannes , Klimant Ingo 
Published: January 2015

AbstractOptical oxygen sensing is of broad interest in many areas of research, such as medicine, food processing, and micro‐ and marine biology. The operation principle of optical oxygen sensors is well established and these sensors are routinely employed in lab and field experiments. Ultratrace oxygen sensors, which enable measurements in the sub‐nanomolar region (dissolved oxygen), are becoming increasingly important. Such sensors prominently exhibit phenomena that complicate calibration and measurements. However, these phenomena are not constrained to ultratrace sensors; rather, these effects are inherent to the way optical oxygen sensors work and may influence any optical oxygen measurement when certain conditions are met. This scenario is especially true for applications that deal with high‐excitation light intensities, such as microscopy and microfluidic applications. Herein, we present various effects that we could observe in our studies with ultratrace oxygen sensors and discuss the reasons for their appearance, the mechanism by which they influence measurements, and how to best reduce their impact. The phenomena discussed are oxygen photoconsumption in the sensor material; depletion of the dye ground state by high‐excitation photon‐flux values, which can compromise both intensity and ratiometric‐based measurements; triplet–triplet annihilation; and singlet‐oxygen accumulation, which affects measurements at very low oxygen concentrations.
Oligo(p‐phenyleneethynylene) (OPE) Molecular Wires: Synthesis and Length Dependence of Photoinduced Charge Transfer in OPEs with Triarylamine and Diaryloxadiazole End Groups
Authors: Linton Katharine E. , Fox Mark A. , Pålsson Lars‐Olof , Bryce Martin R. 
Published: January 2015

AbstractThe systematic synthesis and photophysical, electrochemical and computational studies on an extended series of triphenylamine‐[CC‐1,4‐C6H2(OR)2]n‐CC‐diphenyl‐1,3,4‐oxadiazole dyad molecules (the OR groups are at 2,5‐positions of the para‐phenylene ring and R=C6H13; n=0–5, compounds 1, 2, 3, 4 and 5, respectively) are reported. Related molecules with identical end groups, triphenylamine‐CC‐1,4‐C6H2(OR)2‐CC‐triphenylamine (R=C6H13; 6) and diphenyl‐1,3,4‐oxadiazole‐[CC‐C6H2(OR)2]2‐CC‐diphenyl‐1,3,4‐oxadiazole (R=C6H13; 7) were also studied. These D–B–A 1–5, D–B–D 6 and A–B–A 7 (D=electron donor, B=bridge, A=electron acceptor) systems were synthesized using palladium‐catalysed cross‐coupling reactions of new p‐phenyleneethynylene building blocks. Steady‐state emission studies on the dyads 1–5 reveal a complicated behavior of the emission that is strongly medium dependent. In low polarity solvents the emission is characterized by a sharp high‐energy peak attributed to fluorescence from a locally excited (LE) state. In more polar environments the LE state is effectively quenched by transfer into an intramolecular charge‐transfer (ICT) state. The medium dependence is also observed in the quantum yields (QYs) which are high in cyclohexane and low in acetonitrile, thus also indicating charge‐transfer character. Low‐temperature emission spectra for 2–5 in dichloromethane and diethyl ether also reveal two distinct excited states, namely the LE state and the conventional ICT state, depending on solvent and temperature. Hybrid DFT calculations for 1–7 establish that the OPE bridge is involved in both frontier orbitals where the bridge character increases as the bridge length increases. Computed TD‐DFT data on 1–5 assign the emission maxima in cyclohexane as LE transitions. Each time‐resolved emission measurement on 2–7 in cyclohexane and diethyl ether reveals a wavelength dependent bi‐exponential decay of the emission with a fast component in the 5–61 ps range on blue detection and a slower approximately 1 ns phase, independent of detection wavelength. The fast component is attributed to LE fluorescence and this emission component is rate limited and quenched by transfer into an ICT state. The fast LE fluorescence component varies systematically with conjugation length for the series of D–B–A dyads 2–5. An attenuation factor β of 0.15 Å−1 was determined in accordance with an ICT superexchange mechanism.
An Organocatalytic Mannich/Denitration Reaction for the Asymmetric Synthesis of 3‐Ethylacetate‐Substitued 3‐Amino‐2‐Oxindoles: Formal Synthesis of AG‐041R
Authors: Zhao Kun , Shu Tao , Jia Jiaqi , Raabe Gerhard , Enders Dieter 
Published: January 2015

AbstractThe highly enantioselective organocatalytic addition of ethyl nitroacetate to isatin‐derived N‐Boc ketimines (Boc=tert‐butoxycarbonyl), followed by the removal of the nitro group, is described. The scalable reaction sequence leads to the title compounds as important intermediates of pyrroloindoline alkaloids and related drugs in excellent yields and enantioselectivities. The synthesis of the hexahydrofurano[2,3‐b]indole skeleton, the spirocarbamate oxindole unit, and the formal synthesis of AG‐041R have been carried out to demonstrate the synthetic utility of this protocol.
Amino Acid Derived Phosphine‐Catalyzed Enantioselective 1,4‐Dipolar Spiroannulation of Cyclobutenones and Isatylidenemalononitrile
Authors: Li Yangyan , Su Xiao , Zhou Wei , Li Wenbo , Zhang Junliang 
Published: January 2015

AbstractCyclobutenones have been explored as a new type of chiral 1,4‐dipole four‐carbon synthon, which readily undergoes organophosphine‐mediated CC bond cleavage and asymmetric intermolecular 1,4‐dipolar spiroannulation with isatylidenemalononitrile in the presence of amino acid‐derived chiral phosphine catalyst to furnish enantioenriched 3‐spirocyclohexenone 2‐oxindoles in good yield with up to 87 % ee. To our knowledge, this is the first example of asymmetric transformation of cyclobutenones and the phosphine‐catalyzed asymmetric 1,4‐dipolar cycloaddition consisting of CC bond activation is unprecedented.
Liquid Chromatographic Resolution of Amino Acid Esters of Acyclovir Including Racemic Valacyclovir on Crown Ether‐Based Chiral Stationary Phases
Authors: Ahn Seong Ae , Hyun Myung Ho 
Published: January 2015

AbstractValacyclovir, a potential prodrug for the treatment of patients with herpes simplex and herpes zoster, and its analogs were resolved on two chiral stationary phases (CSPs) based on (3,3’‐diphenyl‐1,1’‐binaphthyl)‐20‐crown‐6 covalently bonded to silica gel. In order to find out an appropriate mobile phase condition, various mobile phases consisting of various organic modifiers in water containing various acidic modifiers were applied to the resolution of valacyclovir and its analogs. When 30% acetonitrile in water containing any of 0.05 M, 0.10 M, or 0.15 M perchloric acid was used as a mobile phase, valacyclovir and its analogs were resolved quite well on the two CSPs with the separation factors (α) in the range of 2.49 ~ 6.35 and resolutions (RS) in the range of 2.95 ~ 12.21. Between the two CSPs, the CSP containing residual silanol protecting n‐octyl groups on the silica surface was found to be better than the CSP containing residual silanol groups. Chirality 27:268–273, 2015. © 2015 Wiley Periodicals, Inc.
Large‐scale tracking and classification for automatic analysis of cell migration and proliferation, and experimental optimization of high‐throughput screens of neuroblastoma cells
Authors: Harder Nathalie , Batra Richa , Diessl Nicolle , Gogolin Sina , Eils Roland , Westermann Frank , König Rainer , Rohr Karl 
Published: January 2015

AbstractComputational approaches for automatic analysis of image‐based high‐throughput and high‐content screens are gaining increased importance to cope with the large amounts of data generated by automated microscopy systems. Typically, automatic image analysis is used to extract phenotypic information once all images of a screen have been acquired. However, also in earlier stages of large‐scale experiments image analysis is important, in particular, to support and accelerate the tedious and time‐consuming optimization of the experimental conditions and technical settings. We here present a novel approach for automatic, large‐scale analysis and experimental optimization with application to a screen on neuroblastoma cell lines. Our approach consists of cell segmentation, tracking, feature extraction, classification, and model‐based error correction. The approach can be used for experimental optimization by extracting quantitative information which allows experimentalists to optimally choose and to verify the experimental parameters. This involves systematically studying the global cell movement and proliferation behavior. Moreover, we performed a comprehensive phenotypic analysis of a large‐scale neuroblastoma screen including the detection of rare division events such as multi‐polar divisions. Major challenges of the analyzed high‐throughput data are the relatively low spatio‐temporal resolution in conjunction with densely growing cells as well as the high variability of the data. To account for the data variability we optimized feature extraction and classification, and introduced a gray value normalization technique as well as a novel approach for automatic model‐based correction of classification errors. In total, we analyzed 4,400 real image sequences, covering observation periods of around 120 h each. We performed an extensive quantitative evaluation, which showed that our approach yields high accuracies of 92.2% for segmentation, 98.2% for tracking, and 86.5% for classification. © 2015 International Society for Advancement of Cytometry
Structure and diversity of phyllostomid bat assemblages on riparian corridors in a human‐dominated tropical landscape
Authors: de la Peña‐Cuéllar Erika , Benítez‐Malvido Julieta , Avila‐Cabadilla Luis Daniel , Martínez‐Ramos Miguel , Estrada Alejandro 
Published: January 2015

AbstractTropical forests around the world have been lost, mainly because of agricultural activities. Linear elements like riparian vegetation in fragmented tropical landscapes help maintain the native flora and fauna. Information about the role of riparian corridors as a reservoir of bat species, however, is scanty. We assessed the value of riparian corridors on the conservation of phyllostomid bat assemblage in an agricultural landscape of southern Mexico. For 2 years (2011–2013), mist‐netting at ground level was carried out twice during the dry season (December to May) and twice during the wet season (June to November) in different habitats: (1) riparian corridors in mature forest, (2) riparian corridors in pasture, (3) continuous forest away from riparian vegetation, and (4) open pastures. Each habitat was replicated three times. To determine the influence of vegetation structure on bat assemblages, all trees (≥10 cm dbh) were sampled in all habitats. Overall, 1752 individuals belonging to 28 species of Phyllostomidae were captured with Sternodermatinae being the most rich and abundant subfamily. Riparian corridors in mature forest and pastures had the greatest species richness and shared 65% of all species. Open pastures had the lowest richness and abundance of bats with no Phyllostominae species recorded. Six of the 18 species recorded could be considered as habitat indicators. There was a positive relationship between bat species composition and tree basal area. Our findings suggest that contrary to our expectations, bats with generalist habits and naturally abundant could be useful detector taxa of habitat modification, rather than bats strongly associated with undisturbed forest. Also in human‐dominated landscapes, the maintenance of habitat elements such as large trees in riparian corridors can serve as reservoirs for bat species, especially for those that are strongly associated with undisturbed forest.
5‐Ferrocenyl‐1H‐tetrazole‐Derived Transition‐Metal Complexes: Synthesis, Crystal Structures and Catalytic Effects on the Thermal Decomposition of the Main Components of Solid Propellants
Authors: Wang Chunyan , Li Jizhen , Fan Xuezhong , Zhao Fengqi , Zhang Weiqiang , Zhang Guofang , Gao Ziwei 
Published: January 2015

AbstractWith the aim of developing low‐migratory burning‐rate (BR) catalysts for solid propellants, a series of transition‐metal complexes of 5‐ferrocenyl‐1H‐tetrazole (HFcTz), [Cu2(bpy)2(FcTz)4]·2C2H5OH (1), [Pb(phen)2(H2O)3](FcTz)2·H2O (3), [Cu(phen)3](FcTz)2·8H2O (4), [Mn(phen)2(H2O)2](FcTz)2 (5), [Mn(bpy)(H2O)4](FcTz)2 (6), [Ni(phen)3](FcTz)2·9H2O (7), and [Co(phen)3](FcTz)2·9H2O (8) (bpy = 2,2′‐bipyridine; phen = 1,10‐phenanthroline), were synthesized and structurally characterized. Only a limited number of single crystals of [Pb2(phen)4(CO3)](FcTz)2·phen·9H2O (2) were formed so only its crystal structure was analyzed. The complexes show high thermal stability. Cyclic voltammetry investigations suggested that 1 and 3–7 exhibit quasireversible redox systems. Their catalytic effects on the thermal degradation of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were evaluated by differential scanning calorimetry (DSC) and thermogravimetric (TG) methods. The optimum content of the new compounds in AP, RDX, and HMX was established to be 5, 5, and 2 wt.‐%, respectively. They exhibit high catalytic activities in the thermal decomposition of AP and RDX. Among them, 6 was found to be the best ferrocene‐based BR catalyst.
Hydropeaking induces losses from a river reach: observations at multiple spatial scales
Authors: Yellen B. , Boutt D.F. 
Published: January 2015

AbstractIn humid regions, where gaining river conditions generally prevail, daily hydroelectric dam releases alter downstream surface water–groundwater interactions by reversing the head gradient between river and adjacent groundwater. Previously, it has been noted that artificial stage changes due to dam releases enhance hyporheic exchange. Here we investigate the regulated Deerfield River in northwestern Massachusetts at multiple scales to evaluate how changing downstream geologic conditions along the river mediate this artificial hyporheic pumping.Water budget analysis indicates that roughly 10% of bank‐stored water is permanently lost from the 19.5‐km river reach, likely as a result of transpiration by bank vegetation. An adjacent reference stream with similar dimensions and geomorphology, but without hydropeaking, shows predictable gaining conditions. Field observations from streambed piezometers and thermistors show that water losses are not uniform throughout the study reach. Riparian aquifer transmissivity in river sub‐reaches largely determines the magnitude of surface water–groundwater exchange as well as net water loss from the river. These newly documented losses from hydropeaking river systems should inform decisions by river managers and hydroelectric operators of additional tradeoffs of oscillatory dam‐release river management. Copyright © 2015 John Wiley & Sons, Ltd.
The Market Maven Crowd: Collaborative Risk‐Aversion and Enhanced Consumption Context Control in an Illicit Market
Authors: O'Sullivan Stephen R. 
Published: January 2015

ABSTRACTContemporary culture is characterized by individual and societal efforts to limit exposure to risk. Paradoxically, many consumers actively pursue high‐risk consumption experiences. High‐risk consumption, coupled with a lack of consumption‐orientated information, amplifies consumer vulnerability. However, consumer‐to‐consumer information sharing can help reduce unwarranted risk and enhance consumption context control. This study investigates the ecstasy “market maven crowd”: an online community anonymously bound by acts of collective market mavenism intended to address the void of market information and reduce the risks thereof. Acts of collective market mavenism include the assimilation and dissemination of scientific ecstasy pill content reports and personal ecstasy consumption tales. The diffusion of market‐orientated information provides consumers with an opportunity to identify, and avert, the serious health risks intrinsic to ecstasy consumption and assert consumption context control. Collaborative market mavenism fosters market policing, which enhances the safety structures of the unregulated ecstasy market. This study contributes to marketing and consumer research by developing an understanding of how consumers collectively adapt to risk online; displaying market mavenism as an innovative framework to examine online consumer‐to‐consumer information sharing; showing how Internet technologies facilitate the emergence of market maven crowds; and providing marketers with guidelines for approaching market maven crowds. Finally, the author discusses the societal implications arising and suggests directions for future research.
Synthesis of Triplet–Triplet Annihilation Upconversion Nanocapsules Under Protective Conditions
Authors: Katta Kartheek , Busko Dmitry , Avlasevich Yuri , Muñoz‐Espí Rafael , Baluschev Stanislav , Landfester Katharina 
Published: January 2015

Triplet–triplet annihilation upconversion (TTA‐UC) nanocapsules are synthesized under oxygen‐protective conditions (i.e., complete darkness and argon atmosphere) by free‐radical miniemulsion polymerization. These conditions help to exclude the oxidation of the emitter molecules caused by singlet oxygen, generated during the synthesis at daylight conditions and oxygen‐rich environment. Subsequently, keeping all the other experimental conditions the same, samples synthesized at protective conditions demonstrate substantially increased UC efficiency. These experimental facts strongly support the hypothesis that posterior removing of oxygen from TTA‐UC nanocapsules is not sufficient to obtain reproducible and sustainable UC results. The schematic representation shows the influence of sunlight on the formation of singlet oxygen and its effect on the triplet–triplet annihilation upconversion process.
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An SMP critical state model for methane hydrate‐bearing sands
Authors: Lin Jeen‐Shang , Seol Yongkoo , Choi Jeong Hoon 
Published: January 2015

SummaryMechanical properties of methane hydrate‐bearing soils are complex. Their behavior undergoes a significant change when hydrates dissociate and become methane gas. On the other hand, methane hydrates are ice‐like compounds and, depending on the hydrate accumulation habits and the degree of hydrate saturation, may cement soil particles into stronger and stiffer soils. A new constitutive model is proposed that is capable of capturing essential characteristics of hydrate‐bearing soils. The core of the model includes the spatial mobilized plane concept; a transformed stress, tij; the critical state; and the subloading framework. The proposed model gives soil responses due to stress changes or hydrate saturation changes or both. The performance of the model has been found satisfactory, over a range of hydrate saturation and confining pressures, using triaxial test data from laboratory‐synthesized samples and from field samples extracted from Nankai Trough, Japan. Copyright © 2015 John Wiley & Sons, Ltd.
Synthesis and characterization of 15% efficient CIGSSe solar cells from nanoparticle inks
Authors: McLeod Steven M. , Hages Charles J. , Carter Nathaniel J. , Agrawal Rakesh 
Published: January 2015

AbstractWe report a total‐area power conversion efficiency of 15% for a copper indium gallium disulfoselenide (CIGSSe) solar cell fabricated from a copper indium gallium disulfide (CIGS) nanoparticle ink based process. Careful optimization of the fabrication process has resulted in a significant improvement in efficiency compared to our previously reported efficiency of 12%. This efficiency ranks among the highest reported in the literature for solution processed CIGSSe. Despite having an absorber thickness of approximately 700–800 nm, which is less than half the thickness of high efficiency devices grown by both coevaporation and solution processes in the literature, our devices show good short‐circuit current (32.1 mA/cm2). Surprisingly, the sintered film shows lateral composition fluctuations, which have not been reported for other high efficiency devices and may be responsible for the lower open circuit voltage (636 mV) observed here. This suggests an avenue for further improvement through optimization of the nanoparticle selenization process to better control composition in the sintered film. Copyright © 2015 John Wiley & Sons, Ltd.
What else do managers need to know about warming rivers? A United Kingdom perspective
Authors: Orr Harriet G. , Johnson Matthew F. , Wilby Robert L. , Hatton‐Ellis Tristan , Broadmeadow Samantha 
Published: January 2015

River flow and water temperature are fundamental controls of freshwater ecosystems. Hence, future warming could impact valued habitats and species, particularly those with cold water preferences (such as salmonids). Warming could also exacerbate existing environmental pressures or diminish the effectiveness of management interventions. Climate model projections provide compelling evidence of the need for adaptation despite uncertainty about the timing, nature, and distribution of impacts on water quality, vulnerable species, and habitats. Low‐regret adaptation options to manage temperature impacts include increasing riparian shade, enhancing thermal refugia, and removing thermal barriers or hotspots. Indirect controls include managing river flows through abstraction and discharge regulation, moderating flow control structures, and manipulating channel hydromorphology. However, fundamental gaps in understanding may limit the effectiveness of some of these measures, leading to undesired side effects, wasted resources, ineffectual outcomes, or limited uptake. These knowledge gaps include where to target measures, how to implement in different situations, how to maximize co‐benefits and integrate with other policy objectives, and how to support implementation across rural and agricultural landscapes. Despite many uncertainties, restoration of riparian shade and river flows has the potential to deliver multiple benefits even if this does not include retarding rates of warming. WIREs Water 2015, 2:55–64. doi: 10.1002/wat2.1062This article is categorized under:

Water and Life > Conservation, Management, and Awareness
Water and Life > Stresses and Pressures on Ecosystems
Science of Water > Water and Environmental Change