bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Activity in the Near‐IR Region: The λ=980 nm Multiplet of Chiral Yb3+ Complexes
Authors: Berardozzi Roberto , Di Bari Lorenzo 
Published: July 2015

AbstractWe used a very simplified electrostatic model based on charge and polarizability of atoms and groups on an organic ligand around a lanthanide ion to predict the near‐infrared electronic circular dichroism (NIR ECD) spectra of Yb3+ (a monoelectronic ion). We tuned our method by using two widely different complexes. The first was the heterobimetallic species CsYb(hfbc)4 [hfbc=(−)‐3‐heptafluorobutyrylcamphorate], in which the ligand is a diketonate and, as such, is endowed with a chromophore with strong UV absorption (π–π*). Its oxygen atoms define a square antiprism, which provides a symmetric coordination polyhedron. The second system was Yb DOTMA [DOTMA=(1R,4R,7R,10R)‐α,α′,α′′,α′′′‐tetramethyl‐1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid], a chiral Yb analogue of Gd DOTA (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid), in which the ligand lacks relevant electronic transitions and provides a dissymmetric cage. The relative weights of dynamic (ligand polarization) and static contributions to Yb NIR ECD were evaluated, and the spectra appear to have been well predicted by theory through the introduction of a heuristic weight factor. To validate the approach and to confirm the value of the weight factor, we applied it to two other compounds, namely, Na3Yb(BINOLate)3 and Yb(BINOLAM)3 [BINOLate=2,2′‐dihydroxy‐1,1′‐binaphthyl; BINOLAM=3,3′‐bis(diethylaminomethyl)‐1‐1′‐bi‐2‐naphthol].
Electrocatalytic Activity of Tungsten Oxide Nanoclusters Grafted on Mesoporous Nitrogen‐Rich Carbon Material in the Dioxygen Reduction Reaction
Authors: Tiwari Aarti , Nagaiah Tharamani C. , Bordoloi Ankur 
Published: July 2015

AbstractNanosized clusters of tungsten oxide grafted onto a mesoporous nitrogen‐rich carbon material (WOx/MNCx) have been synthesized and explored for their remarkable ability towards dioxygen reduction. The composite catalyst exhibits a lower overpotential and significant stability, which paves the way towards improvement of the nonprecious yet proficient electrocatalyst for the oxygen reduction reaction (ORR) occurring at the cathode in alkaline medium. The electrocatalytic activity of the synthesized catalyst towards the ORR have been examined by electrochemical techniques, such as cyclic voltammetry, rotating disk electrode and rotating ring disk electrode measurements, along with electrochemical quartz crystal microbalance studies in alkaline medium. The WOx/MNCx catalyst shows better electrocatalytic activity towards the ORR in alkaline medium and could be used for successful application in low‐temperature fuel cells.
Transesterification of Tributyrin and Dehydration of Fructose over a Carbon‐Based Solid Acid Prepared by Carbonization and Sulfonation of Glucose
Authors: Wang Chuanxu , Yuan Fulong , Liu Lijing , Niu Xiaoyu , Zhu Yujun 
Published: July 2015

AbstractA series of carbon‐based sulfonated solid acid (CS) catalysts can be prepared through a facile method of direct simultaneous carbonization and sulfonation of d‐glucose with concentrated sulfuric acid without a hydrothermal process. Temperature is a key factor in obtaining CS catalysts with higher amounts of ‐SO3H acid sites. The transesterification of tributyrin with methanol and the dehydration of fructose to 5‐hydroxymenthylfurfural (5‐HMF) are investigated over the CS catalysts. The CS‐150 catalyst, which is the CS catalyst prepared at 150 °C, shows much higher catalytic activity to give a tributyrin conversion of 99.4 %. The yield of methyl butyrate is 97.2 % and a remarkably high yield of 5‐HMF (93 %) can be obtained efficiently; these yields result from the high acid density of ‐SO3H. Good linearity is displayed between the total acid density and yield of methyl butyrate/5‐HMF. The CS‐150 catalyst has high stability and good recyclability for the dehydration of fructose.
Biochemical Capacitance of Geobacter Sulfurreducens Biofilms
Authors: Bueno Paulo R. , Schrott Germán D. , Bonanni Pablo S. , Simison Silvia N. , Busalmen Juan P. 
Published: July 2015

AbstractAn electrical model able to decouple the electron pathway from microbial cell machinery impedance terms is introduced. In this context, capacitance characteristics of the biofilm are clearly resolved. In other words, the model allows separating, according to the advantage of frequency and spectroscopic response approach, the different terms controlling the performance of the microbial biofilm respiratory process and thus the directly related electricity production process. The model can be accurately fitted to voltammetry measurements obtained under steady‐state conditions and also to biofilm discharge amperometric measurements. The implications of biological aspects of the electrochemical or redox capacitance are discussed theoretically in the context of current knowledge with regard to structure and physiological activity of microbial Geobacter biofilms.
Hindered Glymes for Graphite‐Compatible Electrolytes
Authors: Shanmukaraj Devaraj , Grugeon Sylvie , Laruelle Stephane , Armand Michel 
Published: July 2015

AbstractOrganic carbonate mixtures are used almost exclusively as lithium battery electrolyte solvents. The linear compounds (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) act mainly as thinner for the more viscous and high‐melting ethylene carbonate but are the least stable component and have low flash points; these are serious handicaps for lifetime and safety. Polyethers (glymes) are useful co‐solvents, but all formerly known representatives solvate Li+ strongly enough to co‐intercalate in the graphite negative electrode and exfoliate it. We have put forward a new electrolyte composition comprising a polyether to which a bulky tert‐butyl group is attached (“hindered glyme”), thus completely preventing co‐intercalation while maintaining good conductivity. This alkyl‐carbonate‐free electrolyte shows remarkable cycle efficiency of the graphite electrode, not only at room temperature, but also at 50 and 70 °C in the presence of lithium bis(fluorosulfonimide). The two‐ethylene‐bridge hindered glyme has a high boiling point and a flash point of 80 °C, a considerable advantage for safety.
Effect of Mesoporous Structured Cathode Materials on Charging Potentials and Rate Capability of Lithium–Oxygen Batteries
Authors: Park Jihee , Jeong Jooyoung , Lee Seonggyu , Jo Changshin , Lee Jinwoo 
Published: July 2015

AbstractSolid and nonconductive discharge products that form on the cathode of Li–O2 batteries are difficult to decompose efficiently into Li+ and O2 during charging, which induces a high overcharge potential, low energy efficiency, and poor cyclability. In this paper, we investigated the effects of the mesoporous structure on the morphology of the discharge products, the capacities of the cells, and the discharging/charging potentials. To isolate the effect of the mesostructures, mesoporous carbons, CMK‐3 and MSU‐F‐C, were used without the addition of other electrocatalysts. The discharge products were confined within the pores. Consequently, the charging potentials were decreased owing to small and amorphous lithium oxides. The large, 3 D interconnected pores of MSU‐F‐C lowered the charging potentials at a high current density and increased the rate capabilities relative to the parameters found for the small pores of CMK‐3. These results demonstrate that control of the porous structure is necessary to enhance the performance of Li–O2 batteries.
Electrolytes Ageing in Lithium‐ion Batteries: A Mechanistic Study from Picosecond to Long Timescales
Authors: Ortiz Daniel , Jiménez Gordon Isabel , Baltaze Jean‐Pierre , Hernandez‐Alba Oscar , Legand Solène , Dauvois Vincent , Si Larbi Gregory , Schmidhammer Uli , Marignier Jean‐Louis , Martin Jean‐Frédéric , Belloni Jacqueline , Mostafavi Mehran , Le Caër Sophie 
Published: July 2015

AbstractThe ageing phenomena occurring in various diethyl carbonate/LiPF6 solutions are studied using gamma and pulse radiolysis as a tool to generate similar species as the ones occurring in electrolysis of Li‐ion batteries (LIBs). According to picosecond pulse radiolysis experiments, the reaction of the electron with (Li+, PF6−) is ultrafast, leading to the formation of fluoride anions that can then precipitate into LiF(s). Moreover, direct radiation‐matter interaction with the salt produces reactive fluorine atoms forming HF(g) and C2H5F(g). The strong Lewis acid PF5 is also formed. This species then forms various R1R2R3P=O molecules, where R is mainly −F, −OH, and −OC2H5. Substitution reactions take place and oligomers are slowly formed. Similar results were obtained in the ageing of an electrochemical cell filled with the same model solution. This study demonstrates that radiolysis enables a description of the reactivity in LIBs from the picosecond timescale until a few days.
Synergistic Carbon Dioxide Capture and Conversion in Porous Materials
Authors: Zhang Yugen , Lim Diane S. W. 
Published: July 2015

AbstractGlobal climate change and excessive CO2 emissions have caused widespread public concern in recent years. Tremendous efforts have been made towards CO2 capture and conversion. This has led to the development of numerous porous materials as CO2 capture sorbents. Concurrently, the conversion of CO2 into value‐added products by chemical methods has also been well‐documented recently. However, realizing the attractive prospect of direct, in situ chemical conversion of captured CO2 into other chemicals remains a challenge.
Freshwater wetlands: fertile grounds for the invasive Phragmites australis in a climate change context
Authors: Tougas‐Tellier Marie‐Andrée , Morin Jean , Hatin Daniel , Lavoie Claude 
Published: July 2015

AbstractClimate change will likely affect flooding regimes, which have a large influence on the functioning of freshwater riparian wetlands. Low water levels predicted for several fluvial systems make wetlands especially vulnerable to the spread of invaders, such as the common reed (Phragmites australis), one of the most invasive species in North America. We developed a model to map the distribution of potential germination grounds of the common reed in freshwater wetlands of the St. Lawrence River (Québec, Canada) under current climate conditions and used this model to predict their future distribution under two climate change scenarios simulated for 2050. We gathered historical and recent (remote sensing) data on the distribution of common reed stands for model calibration and validation purposes, then determined the parameters controlling the species establishment by seed. A two‐dimensional model and the identified parameters were used to simulate the current (2010) and future (2050) distribution of germination grounds. Common reed stands are not widespread along the St. Lawrence River (212 ha), but our model suggests that current climate conditions are already conducive to considerable further expansion (>16,000 ha). Climate change may also exacerbate the expansion, particularly if river water levels drop, which will expose large bare areas propitious to seed germination. This phenomenon may be particularly important in one sector of the river, where existing common reed stands could increase their areas by a factor of 100, potentially creating the most extensive reedbed complex in North America. After colonizing salt and brackishwater marshes, the common reed could considerably expand into the freshwater marshes of North America which cover several million hectares. The effects of common reed expansion on biodiversity are difficult to predict, but likely to be highly deleterious given the competitiveness of the invader and the biological richness of freshwater wetlands.
Quantitative genetics of plumage color: lifetime effects of early nest environment on a colorful sexual signal
Authors: Hubbard Joanna K. , Jenkins Brittany R. , Safran Rebecca J. 
Published: July 2015

AbstractPhenotypic differences among individuals are often linked to differential survival and mating success. Quantifying the relative influence of genetic and environmental variation on phenotype allows evolutionary biologists to make predictions about the potential for a given trait to respond to selection and various aspects of environmental variation. In particular, the environment individuals experience during early development can have lasting effects on phenotype later in life. Here, we used a natural full‐sib/half‐sib design as well as within‐individual longitudinal analyses to examine genetic and various environmental influences on plumage color. We find that variation in melanin‐based plumage color – a trait known to influence mating success in adult North American barn swallows (Hirundo rustica erythrogaster)–is influenced by both genetics and aspects of the developmental environment, including variation due to the maternal phenotype and the nest environment. Within individuals, nestling color is predictive of adult color. Accordingly, these early environmental influences are relevant to the sexually selected plumage color variation in adults. Early environmental conditions appear to have important lifelong implications for individual reproductive performance through sexual signal development in barn swallows. Our results indicate that feather color variation conveys information about developmental conditions and maternal care alleles to potential mates in North American barn swallows. Melanin‐based colors are used for sexual signaling in many organisms, and our study suggests that these signals may be more sensitive to environmental variation than previously thought.
Dioxygen Activation by an in situ Reduced CuII Hydrazone Complex
Authors: Radunsky Christian , Kösters Jutta , Letzel Matthias C. , Yogendra Sivathmeehan , Schwickert Christian , Manck Sinja , Sarkar Biprajit , Pöttgen Rainer , Weigand Jan J. , Neugebauer Johannes , Müller Jens 
Published: July 2015

AbstractA CuII hydrazone complex has been synthesized that can be reduced in situ in boiling methanol to give the corresponding CuI complex. The latter complex readily activates dioxygen under ambient conditions, as was unambiguously shown by isotopic labeling studies. As a consequence of the dioxygen activation, the thienyl moiety appended to the hydrazone ligand is easily oxidized in β position (C–H → C–O), finally leading to a change in the coordination environment of the central metal ion. All relevant complexes have been structurally characterized by single‐crystal X‐ray diffraction analyses. The hydrazone ligand applied in this study does not mimic a biologically relevant coordination motif in copper‐containing oxygenases. Nonetheless, the reactivity of the CuI complex resembles that found in many oxygenases, indicating that hydrazone ligands may be well‐suited for the generation of novel bioinspired oxidation catalysts.
Towards Selective Light‐Activated RuII‐Based Prodrug Candidates
Authors: Mari Cristina , Pierroz Vanessa , Leonidova Anna , Ferrari Stefano , Gasser Gilles 
Published: July 2015

AbstractPhotoactivated chemotherapy (PACT) relies on the use of a drug and light to cause cell death. Unlike photodynamic therapy (PDT), its mechanism of action is independent of the presence of oxygen in tissues. This approach is therefore also effective for tumours characterized by hypoxic conditions. Herein we present the use of three novel RuII–polypyridyl complexes derivatized with a light‐sensitive cage and targeting peptides as selective PACT agents. Light irradiation allowed the selective release of the cytotoxic compounds from the molecular cages in living cells. Further selectivity was conferred on the system by a peptide carrier (i.e., bombesin), which targets receptors overexpressed on the membranes of HeLa cells. As expected, this peptide was found to provide an increased uptake of the systems in HeLa cells compared with normal MRC‐5 cells. As a result, for two of the compounds presented in this study, no cyto‐ or phototoxicity was observed in MRC‐5 cells, whereas in HeLa cells, upon light irradiation, IC50 values of 42.2 and 60.0 μM were obtained, which correspond to a two‐fold increase in toxicity.
Synthesis and Optical Properties of a Series of Green‐Light‐Emitting 2‐(4‐Phenylquinolin‐2‐yl)phenol–BF2 Complexes (Boroquinols)
Authors: Balijapalli Umamahesh , Iyer Sathiyanarayanan Kulathu 
Published: July 2015

AbstractA series of 2‐(4‐phenylquinolin‐2‐yl)phenol derivatives were efficiently synthesized and complexed with boron trifluoride to give fluorescent organoboron complexes. All the synthesized compounds were characterized by 1H, 13C, 11B, 19F NMR, FTIR, and HRMS analyses, and single‐crystal structures of representative compounds were determined to examine the conformations of these compounds. The electronic properties of 2‐(4‐phenylquinolin‐2‐yl)phenol–BF2 complexes were studied by absorption and fluorescence spectroscopy and the complexes were found to be highly emissive in the solid state. The electrochemical properties of boroquinols were measured by using cyclic voltammetry (CV) in acetonitrile with 0.1 M tetrabutyl ammonium hexafluorophosphate as a supporting electrolyte and the LUMO values of boroquinols were calculated to range from –2.64 to –3.46 eV, with HOMO values of –5.32 to –6.10 eV.
Diastereoselective [4+2] Cycloaddition Reaction of 1‐Neomenthyl‐1,2‐diphosphole: Facile Synthesis of P‐Chiral Cage Phosphines
Authors: Zagidullin Almaz , Miluykov Vasili , Polyancev Fedor , Latypov Shamil , Sinyashin Oleg , Lönnecke Peter , Hey‐Hawkins Evamarie 
Published: July 2015

Abstract3,4,5‐Triphenyl‐1‐(+)‐neomenthyl‐1,2‐diphosphole was obtained by alkylation of sodium 3,4,5‐triphenyl‐1,2‐diphosphacyclopentadienide with (–)‐menthyl tosylate. High delocalization within the planar heterocycle of the diphosphole is indicative of low aromaticity. Thus, the [4+2] cycloaddition reaction of this compound with maleic anhydride proceeded under mild conditions with high diastereoselectivity (up to 88 % de) and resulted in the corresponding enantiopure 1,7‐diphosphanorbornadiene as an individual enantiomer. The observed high diastereoselectivity may be explained by thermodynamic control of the reaction.
Synthesis, Characterization and Energetic Properties of 1,3,4‐Oxadiazoles
Authors: Wang Zuoquan , Zhang Hong , Killian Benjamin J. , Jabeen Farukh , Pillai Girinath G. , Berman Heather M. , Mathelier Michael , Sibble Ashani J. , Yeung Justin , Zhou Wenfeng , Steel Peter J. , Hall C. Dennis , Katritzky Alan R. 
Published: July 2015

AbstractAn efficient cyclization between nitro‐substituted benzoic acids and nitro‐substituted benzohydrazides affords 1,3,4‐oxadiazoles. Facile synthesis and a broad substrate scope produce a range of compounds, some of them with potential as high‐energy compounds. Heats of formation (ΔHf) and densities (ρ) were calculated, and heats of decomposition (ΔHd) and combustion (ΔHc) were determined experimentally. The densities of seven of the synthesized compounds were determined by gas pycnometry, and the respective values of detonation velocity (VD), detonation pressure (PD) and specific impulse (ISP) were calculated using the EXPLO5 program. An X‐ray structure of 2‐(2,4‐dinitrophenyl)‐5‐(3,5‐dinitrophenyl)‐1,3,4‐oxadiazole (4n) revealed the non‐planarity of the molecule and afforded a crystal density of 1.698 (at 120 K), close to the pycnometric value of 1.64 at room temperature.
Near‐Infrared Fluorescent 4,4‐Difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene Probes for One‐ and Two‐Photon Fluorescence Bio­imaging
Authors: Kim Bosung , Yue Xiling , Sui Binglin , Zhang Xinfu , Xiao Yi , Bondar Mykhailo V. , Sawada Junko , Komatsu Masanobu , Belfield Kevin D. 
Published: July 2015

AbstractTwo new two‐photon absorbing near‐infrared (NIR) emitting 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) derivatives, DDC and SDC, were designed for one‐ and two‐photon fluorescence microscopy imaging. Linear and nonlinear photophysical properties, including UV/Vis absorption, fluorescence, excitation anisotropy, photostability, and two‐photon absorption cross sections, of the dyes were investigated to assess the potential of using the new probes as bioimaging agents. Cell viability and colocalization studies of DDC with Lysotracker Red, in COS 7 and HCT 116 cells demonstrated not only low toxicity but also selective targeting of lysosomes. SDC was encapsulated in silica‐based nanoparticles for in vitro and ex vivo fluorescence bioimaging. The nanoparticles were modified with an RGD peptide to target αVβ3 integrin. The nanoprobe exhibited good biocompatibility and highly selective uptake in αVβ3 integrin‐overexpressing cancers.
Electrodeposited Iron as a Biocompatible Material for Microneedle Fabrication
Authors: Miller Philip R. , Boehm Ryan D. , Skoog Shelby A. , Edwards Thayne L. , Rodriguez Mark , Brozik Susan , Brener Igal , Byrd Thomas , Baca Justin T. , Ashley Carlee , Narayan Roger J. , Polsky Ronen 
Published: July 2015

AbstractElectroplated iron was investigated as a novel material for microneedle fabrication due to its recent success as a biocompatible metal in other medical device applications. Hollow polymer microneedles were made using a laser direct write process that involved two‐photon polymerization of a commercially available Class 2a biocompatible polymer and subsequent electroplating of this structure with iron. Electroplating bath and deposition conditions were shown to affect the mechanical properties of both iron plated microneedles and iron plated on planar polymer substrates. Conditions for depositing the iron coatings were investigated in terms of grain size, residual strain, and elemental composition for planar iron samples. Fracture strength and puncture mechanics into ex vivo porcine skin for iron coated hollow microneedles were examined. Biocompatibility testing was performed using the MTT assay against human epidermal keratinocytes with several concentrations of iron extract to investigate iron as a material used for transdermal applications. Iron coatings proved to significantly improve the strength of the hollow polymer microneedles and sustained structural integrity up to 7 insertions into porcine skin without bending. A commercially available device (Medtronic MiniMed Quick‐Serter®) was used for controlled application of microneedles into porcine skin and estimations of insertion forces for the device were made. Plating conditions were optimized such that an adherent, uniform, and high purity iron coating was deposited onto polymer substrates and polymer microneedles without delamination or fracturing of the microneedles upon ex vivo insertion into porcine skin.
Bismuth Nanoparticles Incorporated Centri‐voltammetry for Phenol Detection
Authors: Ören Tuğba , Tepeli Yudum , Anik Ülkü 
Published: July 2015

AbstractA novel approach has been developed for phenol detection by combining centri‐voltammetry with bismuth nanoparticles that are used as carrier reagent. The interaction between bismuth and phenol and also the application of centrifugation provide the effective deposition of phenol onto the electrode surface. Direct voltammetric scan without applying any filtration or decantation prevents the analyte loss. As a result, very sensitive results were obtained with linear ranges of 2–75 μM and 100–500 μM and LOD values of 40 nM and 395 nM, respectively. Developed system was also applied for phenol detection in river sample and recovery value was calculated as 115 %.