bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural, Vibrational and Electronic Properties of Defective Single‐Walled Carbon Nanotubes Functionalised with Carboxyl Groups: Theoretical Studies
Authors: Goclon Jakub , Kozlowska Mariana , Rodziewicz Pawel 
Published: August 2015

AbstractCovalent sidewall functionalisation of defective zigzag single‐walled carbon nanotubes [SWCNTs(10,0)] with COOH groups is investigated by using DFT. Four types of point defects are considered: vacancy (V), divacancy [V2(5‐8‐5), V2(555‐777)], adatom (AA) and Stone–Wales (SW). The energetic, structural, electronic and vibrational properties of these systems are analysed. Decreasing reactivity is observed in the following order: AA>V>V2(555‐777)>V2(5‐8‐5)>SW. These studies also demonstrate that the position in which a carboxyl group is attached to a defective SWCNT is of primary importance. Saturation of two‐coordinate carbon atoms in systems with the vacancy V‐7 and with the adatom AA‐1(2) is 3.5–4 times more energetically favourable than saturation of three‐coordinate carbon atoms for all studied systems. Vibrational analysis for these two systems shows significant redshifts of the ν(CO) stretching vibration of 96 and 123 cm−1 compared to that for carboxylated pristine systems. Detailed electronic‐structure analysis of the most stable carboxylated systems is also presented.
Enhanced Lithium‐Ion Storage Capability of a Bismuth Sulfide/Graphene Oxide/Poly(3,4‐ethylenedioxythiophene) Composite
Authors: Mukkabla Radha , Deepa Melepurath , Srivastava Avanish Kumar 
Published: August 2015

AbstractA Bi2S3/graphene oxide (GO) composite enwrapped by a poly(3,4‐ethylenedioxythiophene) (PEDOT) coating was prepared for the first time for use as an anode in Li‐ion batteries. Pristine Bi2S3 nanoflowers and composites of Bi2S3/GO and Bi2S3/GO/PEDOT were assembled into half cells with Li metal as the counter electrode, and initial discharge capacities of 833, 1020, and 1300 mAh g−1, respectively, were obtained. Composites of Bi2S3/GO/PEDOT and Bi2S3/GO showed superior cycling stability and better rate capability than pristine Bi2S3. GO provides highly conducting interconnections, which allow facile propagation of electrons during charge/discharge, and this improves the ion‐uptake capability of the Bi2S3 nanoflowers and also increases the rate capability. PEDOT furnishes a protective coating that prevents detachment of the material from the current collector during cycling, and it also imparts better cycling stability to the Bi2S3/GO/PEDOT composite.
Surface Buckling and Subsurface Oxygen: Atomistic Insights into the Surface Oxidation of Pt(111)
Authors: Fantauzzi Donato , Mueller Jonathan E. , Sabo Lehel , van Duin Adri C. T. , Jacob Timo 
Published: August 2015

AbstractPlatinum is a catalyst of choice in scientific investigations and technological applications, which are both often carried out in the presence of oxygen. Thus, a fundamental understanding of platinum’s (electro)catalytic behavior requires a detailed knowledge of the structure and degree of oxidation of platinum surfaces in operando. ReaxFF reactive force field calculations of the surface energies for structures with up to one monolayer of oxygen on Pt(111) reveal four stable surface phases characterized by pure adsorbate, high‐ and low‐coverage buckled, and subsurface‐oxygen structures, respectively. These structures and temperature programmed desorption (TPD) spectra simulated from them compare favorably with and complement published scanning tunneling microscopy (STM) and TPD experiments. The surface buckling and subsurface oxygen observed here influence the surface oxidation process, and are expected to impact the (electro)catalytic properties of partially oxidized Pt(111) surfaces.
How CO2 Interacts with Carboxylic Acids: A Rotational Study of Formic Acid–CO2
Authors: Vigorito Annalisa , Gou Qian , Calabrese Camilla , Melandri Sonia , Maris Assimo , Caminati Walther 
Published: August 2015

AbstractThe rotational spectra of the 1:1 formic acid–carbon dioxide molecular complex and of its monodeuterated isotopologues are analysed in the 6.5–18.5 and 59.6–74.4 GHz frequency ranges using a pulsed jet Fourier transform microwave spectrometer and a free‐jet absorption millimetre wave spectrometer, respectively. Precise values of the rotational and quartic centrifugal distortion constants are obtained from the measured frequencies, and quadrupole coupling constants are determined from the deuterium hyperfine splittings. Structural parameters are estimated from the moments of inertia and their differences among isotopologues: the complex has a planar structure with the two subunits held together by a HC(O)OH⋅⋅⋅O=CO (2.075 Å) and a HC(OH)O⋅⋅⋅CO2 (2.877 Å) interactions. The ab initio intermolecular binding energy, obtained at the counterpoise corrected MP2/aug‐cc‐pVTZ level of calculation, is De=17 kJ mol−1.
One‐pot Synthesis of PtSn Bimetallic Composites and Their Application as Highly Active Catalysts for Ethanol Electrooxidation
Authors: Feng Yue , Wang Caiqin , Bin Duan , Zhai Chunyang , Ren Fangfang , Yang Ping , Du Yukou 
Published: August 2015

AbstractPtSn nanoparticles with different molar ratio are fabricated by chemical reduction to form a relatively efficient catalyst for ethanol electrooxidation in an alkaline solution of KOH (1.0 m) containing C2H5OH (1.0 m). The surface composition and structure of the as‐prepared catalysts are characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and energy dispersive X‐ray spectroscopy (EDX). Cyclic voltammogram (CV) and chronoamperometric (CA) measurements are used to evaluate the electrochemical activity and stability of the as‐prepared catalysts. As the content of Sn in the catalysts changed, the catalysts showed different catalytic activity. The results indicate that the moderate addition of Sn can enhance the catalytic activity of Pt catalyst, and Pt3Sn1 displays the highest catalytic activity and stability among the as‐synthesized PtSn nanoparticles during the electrooxidation of ethanol.
Catechol‐O‐methyltransferase Val158met polymorphism interacts with early experience to predict executive functions in early childhood
Authors: Blair Clancy , Sulik Michael , Willoughby Michael , Mills‐ Koonce Roger , Petrill Stephen , Bartlett Christopher , Greenberg Mark ,   the Family Life Project Investigators
Published: August 2015

ABSTRACTNumerous studies demonstrate that the Methionine variant of the catechol‐O‐methyltransferase Val158Met polymorphism, which confers less efficient catabolism of catecholamines, is associated with increased focal activation of prefrontal cortex (PFC) and higher levels of executive function abilities. By and large, however, studies of COMT Val158Met have been conducted with adult samples and do not account for the context in which development is occurring. Effects of early adversity on stress response physiology and the inverted U shape relating catecholamine levels to neural activity in PFC indicate the need to take into account early experience when considering relations between genes such as COMT and executive cognitive ability. Consistent with this neurobiology, we find in a prospective longitudinal sample of children and families (N = 1292) that COMT Val158Met interacts with early experience to predict executive function abilities in early childhood. Specifically, the Valine variant of the COMT Val158Met polymorphism, which confers more rather than less efficient catabolism of catecholamines is associated with higher executive function abilities at child ages 48 and 60 months and with faster growth of executive function for children experiencing early adversity, as indexed by cumulative risk factors in the home at child ages 7, 15, 24, and 36 months. Findings indicate the importance of the early environment for the relation between catecholamine genes and developmental outcomes and demonstrate that the genetic moderation of environmental risk is detectable in early childhood. © 2015 Wiley Periodicals, Inc. Dev Psychobiol 57: 833–841, 2015.
Efficient human face detection in infancy
Authors: Jakobsen Krisztina V. , Umstead Lindsey , Simpson Elizabeth A. 
Published: August 2015

ABSTRACTAdults detect conspecific faces more efficiently than heterospecific faces; however, the development of this own‐species bias (OSB) remains unexplored. We tested whether 6‐ and 11‐month‐olds exhibit OSB in their attention to human and animal faces in complex visual displays with high perceptual load (25 images competing for attention). Infants (n = 48) and adults (n = 43) passively viewed arrays containing a face among 24 non‐face distractors while we measured their gaze with remote eye tracking. While OSB is typically not observed until about 9 months, we found that, already by 6 months, human faces were more likely to be detected, were detected more quickly (attention capture), and received longer looks (attention holding) than animal faces. These data suggest that 6‐month‐olds already exhibit OSB in face detection efficiency, consistent with perceptual attunement. This specialization may reflect the biological importance of detecting conspecific faces, a foundational ability for early social interactions. © 2015 Wiley Periodicals, Inc. Dev Psychobiol 58:129–136, 2016.
The challenge of accurately documenting bee species richness in agroecosystems: bee diversity in eastern apple orchards
Authors: Russo Laura , Park Mia , Gibbs Jason , Danforth Bryan 
Published: August 2015

AbstractBees are important pollinators of agricultural crops, and bee diversity has been shown to be closely associated with pollination, a valuable ecosystem service. Higher functional diversity and species richness of bees have been shown to lead to higher crop yield. Bees simultaneously represent a mega‐diverse taxon that is extremely challenging to sample thoroughly and an important group to understand because of pollination services. We sampled bees visiting apple blossoms in 28 orchards over 6 years. We used species rarefaction analyses to test for the completeness of sampling and the relationship between species richness and sampling effort, orchard size, and percent agriculture in the surrounding landscape. We performed more than 190 h of sampling, collecting 11,219 specimens representing 104 species. Despite the sampling intensity, we captured <75% of expected species richness at more than half of the sites. For most of these, the variation in bee community composition between years was greater than among sites. Species richness was influenced by percent agriculture, orchard size, and sampling effort, but we found no factors explaining the difference between observed and expected species richness. Competition between honeybees and wild bees did not appear to be a factor, as we found no correlation between honeybee and wild bee abundance. Our study shows that the pollinator fauna of agroecosystems can be diverse and challenging to thoroughly sample. We demonstrate that there is high temporal variation in community composition and that sites vary widely in the sampling effort required to fully describe their diversity. In order to maximize pollination services provided by wild bee species, we must first accurately estimate species richness. For researchers interested in providing this estimate, we recommend multiyear studies and rarefaction analyses to quantify the gap between observed and expected species richness.
Early subtropical forest growth is driven by community mean trait values and functional diversity rather than the abiotic environment
Authors: Kröber Wenzel , Li Ying , Härdtle Werner , Ma Keping , Schmid Bernhard , Schmidt Karsten , Scholten Thomas , Seidler Gunnar , von Oheimb Goddert , Welk Erik , Wirth Christian , Bruelheide Helge 
Published: August 2015

AbstractWhile functional diversity (FD) has been shown to be positively related to a number of ecosystem functions including biomass production, it may have a much less pronounced effect than that of environmental factors or species‐specific properties. Leaf and wood traits can be considered particularly relevant to tree growth, as they reflect a trade‐off between resources invested into growth and persistence. Our study focussed on the degree to which early forest growth was driven by FD, the environment (11 variables characterizing abiotic habitat conditions), and community‐weighted mean (CWM) values of species traits in the context of a large‐scale tree diversity experiment (BEF‐China). Growth rates of trees with respect to crown diameter were aggregated across 231 plots (hosting between one and 23 tree species) and related to environmental variables, FD, and CWM, the latter two of which were based on 41 plant functional traits. The effects of each of the three predictor groups were analyzed separately by mixed model optimization and jointly by variance partitioning. Numerous single traits predicted plot‐level tree growth, both in the models based on CWMs and FD, but none of the environmental variables was able to predict tree growth. In the best models, environment and FD explained only 4 and 31% of variation in crown growth rates, respectively, while CWM trait values explained 42%. In total, the best models accounted for 51% of crown growth. The marginal role of the selected environmental variables was unexpected, given the high topographic heterogeneity and large size of the experiment, as was the significant impact of FD, demonstrating that positive diversity effects already occur during the early stages in tree plantations.
Phylogenetic and ecological patterns in nighttime transpiration among five members of the genus Rubus co‐occurring in western Oregon
Authors: McNellis Brandon , Howard Ava R. 
Published: August 2015

AbstractNighttime transpiration is a substantial portion of ecosystem water budgets, but few studies compare water use of closely related co‐occurring species in a phylogenetic context. Nighttime transpiration can range up to 69% of daytime rates and vary between species, ecosystem, and functional type. We examined leaf‐level daytime and nighttime gas exchange of five species of the genus Rubus co‐occurring in the Pacific Northwest of western North America in a greenhouse common garden. Contrary to expectations, nighttime transpiration was not correlated to daytime water use. Nighttime transpiration showed pronounced phylogenetic signals, but the proportion of variation explained by different phylogenetic groupings varied across datasets. Leaf osmotic water potential, water potential at turgor loss point, stomatal size, and specific leaf area were correlated with phylogeny but did not readily explain variation in nighttime transpiration. Patterns in interspecific variation as well as a disconnect between rates of daytime and nighttime transpiration suggest that variation in nighttime water use may be at least partly driven by genetic factors independent of those that control daytime water use. Future work with co‐occurring congeneric systems is needed to establish the generality of these results and may help determine the mechanism driving interspecific variation in nighttime water use.
Synthesis and Structures of N‐Heterocyclic Carbene–Sulfonate Ruthenium Complexes and Their Applications in the Ring‐Opening Metathesis Polymerization of Norbornene
Authors: Li Minliang , Song Haibin , Wang Baiquan 
Published: August 2015

AbstractA series of N‐heterocyclic carbene–sulfonate (NHC–sulfonate) p‐cymene ruthenium complexes (2a–2d) were synthesized in high yields from the reactions of NHC–sulfonate ligands with Ag2O and [(p‐cymene)RuCl2]2. All of the complexes were characterized fully by 1H and 13C NMR spectroscopy, high‐resolution mass spectrometry, and elemental analysis. The molecular structures of 2b and 2d were determined by single‐crystal X‐ray diffraction analysis. Upon activation with Et2AlCl, the ruthenium complexes 2a–2d showed excellent activities for the ring‐opening metathesis polymerization of norbornene and produced polymers with high molecular weights and narrow molecular weight distributions. Complex 2a can also efficiently catalyze the copolymerization of norbornene and cyclooctene. All of the obtained polymers were characterized by 1H and 13C NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC).
Sequence‐based proline incorporation improves the thermostability of Candida albicans lipase Lip5
Authors: Yuan Dongjuan , Zhao Zexin , Wang Xiumei , Guo Shaohua , Yang Bo , Wang Yonghua 
Published: August 2015

Increasing kinetic stability of industrial enzymes is a key objective of protein engineering. In this study, a cold‐active Candida albicans lipase Lip5 was selected as a model to improve its stability. With no 3D structure available, multiple‐sequence alignment of homologous lipases with different kinetic stabilities in the same superfamily was used to identify the mostly likely positions relevant to protein stability; these positions (V39, I52, and I290) were selected for proline incorporation in Lip5 as a strategy to increase the protein stability. Of the mutants generated, two of them (V39P and I290P) displayed a twofold increase in kinetic stability and improved thermodynamic stability as well. None of the mutants exhibited secondary or tertiary structure changes as shown by circular dichroism and fluorescence spectroscopy analyses. These results demonstrate that in the absence of 3D structure, multiple‐sequence alignment could be a useful tool to direct proline incorporation for lipase stability engineering.Practical applications: In the absence of a 3D structure, multiple‐sequence alignment‐based proline incorporation is a useful tool to engineer lipase towards improved stability.The kinetic stability of Lip5 and mutants showed that t1/2 values of mutants V39P and I290P were approximately twice as high as that of the wild type. The ΔΔGs of these two mutants increased by 2.35 and 2.03 KJ/mol, respectively, compared with wild type, suggesting higher energy barriers against thermal inactivation for V39P and I290P. Proline incorporation at position 39 or 290 increases the kinetic stability of Lip5.
Preparation of 1,2,5‐Trisubstituted 1H‐Imidazoles from Ketenimines and Prop­arg­ylic Amines by Silver‐Catalyzed or Iodine‐Promoted Electrophilic Cyclization Reaction of Alkynes
Authors: Zhou Xiaorong , Jiang Zheng , Xue Lexing , Lu Ping , Wang Yanguang 
Published: August 2015

AbstractFrom readily available propargylic amines, 1,2,5‐trisubstituted imidazoles are efficiently obtained through a cascade reaction catalyzed by AgOTf or promoted by molecular iodine. The AgOTf‐catalyzed reaction involves nucleophilic addition of propargylic amine to ketenimine, a silver‐catalyzed electrophilic cyclization reaction of alkyne, and a tautomerism/isomerism/metal‐H exchange cascade. The iodine‐mediated counterpart yields 5‐formyl‐1,2‐disubtituted imidazoles, which presumably includes a cascade hydrolysis/oxidation reaction. Furthermore, the presented protocol can be scaled up and the resultant 1,2,5‐trisubstituted imidazole can be converted into fused indeno[1,2‐d]imidazole.
A Novel Method of High Sensitive Determination of Prednisolone on Renewable Mercury Film Silver Based Electrode
Authors: Smajdor Joanna , Piech Robert , Paczosa‐Bator Beata 
Published: August 2015

AbstractFast and sensitive method of prednisolone determination at renewable mercury film electrode using differential pulse adsorptive stripping voltammetry (DPAdSV) was successfully developed. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition were optimized. A linear voltammetric response for analyte was obtained in the concentration range from 0.05 µmol L−1(18 µg L−1) to 2.25 µmol L−1(0.81 mg L−1), with a detection limit of 0.01 µmol L−1for preconcentration time of 20 s. Repeatability of method was determined as RSD % for prednisolone concentration of 0.04 µmol L−1as 1.6 % (n=9). The proposed method was successfully applied and validated by recovery parameter of prednisolone in simulated sample and pharmaceutical product.
Tailoring Commercially Available Raw Materials for Lithium–Sulfur Batteries with Superior Performance and Enhanced Shelf Life
Authors: Thieme Sören , Oschatz Martin , Nickel Winfried , Brückner Jan , Kaspar Jörg , Althues Holger , Kaskel Stefan 
Published: August 2015

AbstractPhysical activation with CO2 is used to modify the micro‐, meso‐, and macropore system of commercial, highly branched carbon black (CB) particles. Due to the increased total porosity and high surface area of 1747 m2 g−1 the completeness of sulfur infiltration in intra‐particle pores of CB is promoted. This is found to not only minimize sulfur agglomeration on the particle surface but also reduce self‐discharge, that is, polysulfide leakage. Wrapping the CB/sulfur composite with a poly(ethylene oxide)/poly(vinylpyrrolidone) film further triggers a synergy allowing for faster sulfur conversion with increased reversibility. Thus, an initial capacity of 1238 mAh g−1S at C/10 and a stable capacity of 1015 mAh g−1S after 50 cycles were obtained, combined with a superior rate capability up to 2 C (≈7.5 mA cm−2) and extremely slow self‐discharge over 100 days (open‐circuit voltage>2.30 V).
Comparative response and performance of base‐isolated and fixed‐base structures
Authors: Chimamphant Sarun , Kasai Kazuhiko 
Published: August 2015

SummaryA building with a seismic isolation system, in an earthquake, is recognized as producing substantially smaller accelerations and deformations compared with a building that use other systems. This type of system is therefore expected to better protect the building's nonstructural components, equipment, and other contents that are essential for the activities conducted in the building. Unlike many available studies on building responses, only a small number of studies on a buildings' nonstructural component responses are available, and no study has directly addressed building performance with regard to nonstructural component protection. This paper therefore measures the performance of various seismically isolated buildings. Specifically, the effects of important structural parameters, namely, isolation stiffness, isolation damping ratio, and number of stories on the response of base‐isolated structures are investigated parametrically. Ground motions with 2% exceedence in 50years Maximum Considered Earthquake (MCE) are used. Performance is compared with that of fixed‐base structures in order to present data that will be useful in justifying the more costly technology. The buildings are 3, 9, and 20 stories, represented by MDOF shear‐beam models. As examples of displacement‐sensitive and acceleration‐sensitive components, partition walls and ceilings are considered, respectively. The Pacific Earthquake Engineering Research Center performance‐based earthquake engineering methodology is adopted to evaluate the failure return periods of the examples based on their available fragility curves. In addition, the curves are varied hypothetically to understand the sensitivity of the return period to the curve features. Then, the median and dispersion of fragility curves required to satisfy the components' desired failure return period are obtained. Copyright © 2015 John Wiley & Sons, Ltd.