bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron‐Transfer Kinetics in Polymetallic Carbon‐Rich Ruthenium(II) Bis(σ‐arylacetylides) Wires Connected to Gold
Authors: Mulas Andrea , Hervault Yves‐Marie , Norel Lucie , Rigaut Stéphane , Lagrost Corinne 
Published: July 2015

AbstractMolecular wires consisting of RuII bis(σ‐arylacetylide) organometallics functionalized with different anchoring groups (thiol, isocyanide) connected with different bridges [Ø, −CH2−, −O−(CH2)6−] were self‐assembled onto gold surfaces. The materials were characterized through wettability, ellipsometric, infrared absorption reflection, and electrochemical measurements. The dynamics of the electron transfers within the monolayers were examined with high‐speed voltammetry. Similar fast electron‐transfer dynamics (104 s−1) associated with discrete oxidation events (up to four distinct oxidation states) at remarkably low potentials (≤0.7 V vs. SCE) were observed for all complexes. Neither the extension of the molecular wires, nor the variation in the anchoring/bridging units, led to the decrease in electron‐transfer kinetics. These results highlight the potential of RuII bis(σ‐arylacetylide) complexes as a charge‐storage medium for processing information in multibit devices with low power consumption.
Cyclotrimerization‐Induced Chiral Supramolecular Structures of 4‐Ethynyltriphenylamine on Au(111) Surface
Authors: Xiang Feifei , Lu Yan , Li Chao , Song Xin , Liu Xiaoqing , Wang Zhongping , Liu Juan , Dong Mingdong , Wang Li 
Published: July 2015

AbstractCyclotrimerization‐induced chiral supramolecular structures of 4‐ethynyltriphenylamine (ETPA) have been synthesized on the Au(111) surface through alkyne‐based reactions. Whereas the ETPA molecules adsorbed on the Au(111) surface remain inert and form a close‐packed self‐assembled structure at room temperature, the combination of scanning tunneling microscopy observations and theoretical calculations unambiguously reveal that the ETPA molecules cyclotrimerize to form new trimer‐like species—1,3,5‐tris[4‐(diphenylamino)phenyl]benzene (TPAPB)—after annealing at 323 K. Further annealing drives these cyclotrimerized TPAPB molecules to form chiral hexagonal supramolecular structures with an extraordinary self‐healing ability.
Two Symmetrically Bis‐substituted Pyrene Derivatives: Synthesis, Photoluminescence, and Electroluminescence
Authors: Gong Xiaojie , Xie Xiang , Chen Naiwu , Zheng Chaoyue , Zhu Jie , Chen Runfeng , Huang Wei , Gao Deqing 
Published: July 2015

AbstractTwo kinds of cyanophenyl terminated pyrene derivatives for organic light‐emitting diodes were synthesized and characterized by UV/Vis, fluorescence (FL), 1H NMR, MALDI‐TOF, CV and TGA. Both compounds exhibited blue photoluminescence and high fluorescent quantum yield of 85% and 75% in solutions. Due to the presence of acetylene spacer, the compound distinguishes itself by high coplanarity, high thermal stability, little Stokes' shift and clear excimer formation in the solid state from the acetylene‐free compound. In order to suppress the molecular aggregation, the electroluminescent properties were studied by doing the materials in PVK. The result proved that energy transfer happened from the host PVK to the materials.
An imputation based empirical likelihood approach to pretest–posttest studies
Authors: Chen Min , Wu Changbao , Thompson Mary E. 
Published: July 2015

AbstractPretest–posttest studies are an important and popular method for assessing treatment effects or the effectiveness of an intervention in many areas of scientific research. There are two distinct features for this type of study: availability of baseline information for all subjects in the study and missingness by design of measures of the responses. Important recent research advances on this topic include Leon et al. (2003) on efficient estimation of the treatment effect, and Huang et al. (2008) on a semi‐parametric estimation procedure based on empirical likelihood (EL) where the mean responses for the treatment group and the control group are handled separately. EL ratio confidence intervals or tests for the treatment effect, however, cannot be constructed under the approach used by Huang et al. (2008). In this paper, we use an alternative EL formulation, which directly involves the parameter of interest, i.e., the treatment effect, and incorporates baseline information through an imputation approach. Our focus is to derive the EL ratio confidence intervals and tests for the treatment effect under the proposed imputation‐based framework. Theoretical results are developed, and finite sample performances of the proposed methods with comparison to existing approaches are investigated through simulation studies. An application to a real data set is also presented. The Canadian Journal of Statistics 43: 378–402; 2015 © 2015 Statistical Society of Canada
Gas‐Induced Reversible Dispersion/Aggregation of Graphene
Authors: He Shuai , Qu Meizhen , Feng Yujun 
Published: July 2015

AbstractThe low dispersibility of graphene in water, given its hydrophobic nature, is considered a serious problem that limits its use. Here, we describe a method to stably disperse graphene using a dispersant containing a tertiary amine and a pyrene group. The dispersant modifies the graphene surface via π–π stacking, allowing it to be dispersed in water. The dispersant undergoes a hydrophobic–hydrophilic transition upon being stimulated by CO2 and N2, exhibiting a faster response (reaction time of 1.5 min) and lower recovery temperature (40 °C) than those of compounds with amidine‐like structures. We found that the graphene modified by this gas‐sensitive dispersant exhibited reversible dispersion/aggregation behavior upon the bubbling/removal of CO2. The proposed method is a simple one for the reversible dispersion/aggregation of graphene by stimulating it with a gas and should be suitable for fabricating sensors, drug‐delivery systems, “smart” surfaces, and switching devices.
Synthesis and Solid‐State NMR Studies of Proton‐Conducting Mesoporous Niobium Oxide Polymer Composites with Nafion‐Like Thermal Durability
Authors: Turley Jonathan P. , Romer Frederik , Trudeau Michel L. , Smith Mark E. , Hanna John V. , Antonelli David M. 
Published: July 2015

AbstractProton conductivity and thermal durability studies were performed on a series of mesoporous Nb2O5 composites with naphthalene sulfonate formaldehyde resin polymerized within the pores. The proximity of the sulfonate groups of the polymer to the walls of the oxide mesostructure was deliberately tailored to ensure superior dehydration resistance crucial to proton conductivity. Initially characterized by nitrogen adsorption, XRD, TGA and STEM, subsequent study using impedance spectroscopy over a temperature range of 20–150 °C established their proton conductivity performance. The most promising sample displayed a conductivity of 21.77 mS cm−1 at 80 °C surpassing the literature value for Nafion 117 (8 mS cm−1) as measured in our labs using the same setup. Subsequent thermal durability tests demonstrated that this composite maintains superior conductivity to Nafion 117 at 80 °C for the length of the study (24 h). These observations were rationalized by in depth solid‐state NMR studies.
Indirect effects of habitat disturbance on invasion: nutritious litter from a grazing resistant plant favors alien over native Collembola
Authors: Leinaas Hans Petter , Bengtsson Jan , Janion‐Scheepers Charlene , Chown Steven L. 
Published: July 2015

AbstractBiological invasions are major threats to biodiversity, with impacts that may be compounded by other forms of environmental change. Observations of high density of the invasive springtail (Collembola),Hypogastrura manubrialisin heavily grazed renosterveld vegetation in the Western Cape, South Africa, raised the question of whether the invasion was favored by changes in plant litter quality associated with habitat disturbance in this vegetation type. To examine the likely mechanisms underlying the high abundance ofH. manubrialis, cages with three types of naturally occurring litter with different nutrient content were placed out in the area and collected after different periods of time.Hypogastrura manubrialiswas mainly found in the nutrient‐rich litter of the yellowbush (Galenia africana), which responds positively to disturbance in the form of overgrazing. This suggests that invasion may have been facilitated by a positive interaction with this grazing resistant plant. By contrast, indigenous Collembola were least abundant in yellowbush litter. Negative correlations between high abundance ofH. manubrialisand the abundance and diversity of other species suggest that competitive interactions might underlie low abundance of these other species at the patch level. Group behavior enablesH. manubrialisto utilize efficiently this ephemeral, high quality resource, and might improve its competitive ability. The results suggest that interactions among environmental change drivers may lead to unforeseen invasion effects.H. manubrialisis not likely to be very successful in un‐grazed renosterveld, but in combination with grazing, favoring the nutrient‐rich yellowbush, it may become highly invasive. Field manipulations are required to fully verify these conclusions.
Experimental and Theoretical Investigations of CO2 Sorption by a 3D In‐MOF with Multiple 1D Channels
Authors: Gu Ja‐Min , Hong Jin‐Yeon , Won Yong Sun , Park Sung Soo , Huh Seong 
Published: July 2015

AbstractThe CO2 sorption capacity of the 3D In‐MOF (Et2NH2)[In(2,6‐NDC)2]·2H2O·DEF (I) (where 2,6‐NDC is 2,6‐naphthalenedicarboxylate and DEF is N,N‐diethylformamide) was investigated. The solvent‐free I contains three distinct types of 1D micropores with different shapes and pore dimensions. The evacuated I sorbed 297.2 cm3 g–1 (13.3 mmol g–1) of CO2 at 196 K, 72.2 cm3 g–1 (3.22 mmol g–1) at 273 K, and 39.8 cm3 g–1 (1.78 mmol g–1) at 298 K. The difference between the uptake at 196 K and those at 273 and 298 K is relatively large. The shapes of the sorption isotherms are also dramatically different. At 196 K, the adsorption–desorption isotherms are S‐shaped without significant hysteretic behavior between the adsorption and desorption branches. On the contrary, the adsorption isotherms measured at 273 and 298 K fit well with the Langmuir–Freundlich equation. The low‐surface‐coverage isosteric heat (Qst) of CO2 adsorption by I is 19.6 kJ mol–1. Detailed estimations of the adsorption sites for CO2 were then performed by DFT calculations. The calculated binding energies were typically dependent on the dimension of the micropores when nonbonding (van der Waals) interactions were considered; the larger the micropore dimensions, the smaller the calculated binding energy. In addition, not only the framework CH···OCO contacts for Ch3 but also the counter‐cation CH···OCO contacts for Ch1 and Ch2 were found to be important.
Mechanisms of Oxygen Atom Transfer between Main‐Group Elements
Authors: Conradie Jeanet , Berg Steffen , Ghosh Abhik 
Published: July 2015

AbstractOxygen atom transfer (OAT) between main‐group elements is pivotal to a number of industrial processes such as the synthesis of thionyl chloride (SO3 + SCl2 → SO2 + SOCl2) and sodium chlorate (3 NaOCl → NaClO3 + 2 NaCl), as well as the historic method of CO detection in mines via its reaction with I2O5 (I2O5 + 5 CO → I2 + 5 CO2). Surprisingly, little is known about the mechanisms of these and other OAT reactions involving main‐group elements. Even the basic question as to whether such reactions are one‐step, SN2‐like displacements or multistep, involving oxo‐bridged intermediates, remains largely unanswered. Extensive density functional theory calculations reported herein indicate a direct, SN2‐like pathway as the norm for such processes.
Derivation of water quality standards for carbamazepine, metoprolol, and metformin and comparison with monitoring data
Authors: Moermond Caroline T.A. , Smit C. Els 
Published: July 2015

Abstract

Environmental quality standards (EQSs) for 3 pharmaceuticals in surface water were derived: carbamazepine (epilepsy), metoprolol (heart failure), and metformin (diabetes). In recent years, these pharmaceuticals have been detected frequently in Dutch surface waters. The proposed standards are based on ecotoxicity data from national and European authorization dossiers and additional information obtained from open literature. The methods used are in accordance with the methodology of the Water Framework Directive and national frameworks for risk limit derivation. Only the exposure route regarding direct ecotoxic effects on ecosystems could be taken into account for deriving EQSs. The exposure route of secondary poisoning of fish-eating animals was not triggered, and not enough data were available or accessible to derive an EQS for the exposure of humans due to consumption of fish. Monitoring data for surface waters worldwide show that the proposed quality standards for carbamazepine may be exceeded. It could be expected that when carbamazepine use increases or effluents are diluted less during dry seasons, standards will be exceeded more often. Environ Toxicol Chem 2016;35:882–888. © 2015 SETAC
Contrasting PCB bioaccumulation patterns among Lake Huron lake trout reflect basin-specific ecology
Authors: Paterson Gordon , Ryder Mark , Drouillard Ken G. , Haffner G. Douglas 
Published: July 2015

Abstract

This study collected multiple age classes of lake trout from Lake Huron's Main Basin, Georgian Bay, and North Channel regions to compare and contrast top predator polychlorinated biphenyl (PCB) bioaccumulation patterns in separate compartments of the same ecosystem. Sum PCB concentrations were highest for Main Basin (260 ± 24.9 ng g−1 wet wt) fish, followed by Georgian Bay (74.6 ± 16.2 ng g−1) and North Channel (42.0 ± 3.3 ng g−1) fish. Discriminant functions analysis of lake trout PCB profiles and stable carbon (δ13C) and nitrogen (δ15N) isotope values clearly distinguished fish by location, indicating high degrees of basin fidelity throughout their lifetimes in addition to highly contrasting PCB bioaccumulation profiles. These unique profiles were not attributable to significant differences in lake trout lipid contents (p = 0.856) or trophic position (δ15N; p = 0.334), with rainbow smelt representing the primary prey across the basins. Furthermore, significant differences were observed among the basins for the relationships between PCB biomagnification factors and hydrophobicity. An empirical model for predicting PCB biomagnification in Lake Huron lake trout indicated that basin-specific population growth rates and prey abundances were significant for explaining these contrasting patterns of PCB bioaccumulation. The results of the present study are fundamental for understanding the role of ecology in legacy persistent organic pollutant (POP) bioaccumulation. Specifically, ecosystem characteristics such as prey abundances, foraging ecology, and ultimately consumer growth can regulate the variability of legacy POP bioaccumulation as observed within and among a wide range of freshwater ecosystems. Environ Toxicol Chem 2016;35:65–73. © 2015 SETAC
Effect of test concentration in the ready biodegradability test for chemical substances: Improvement of OECD test guideline 301C
Authors: Nabeoka Ryosuke , Taruki Masanori , Kayashima Takakazu , Yoshida Tomohiko , Kameya Takashi 
Published: July 2015

Abstract

In Japan, understanding the environmental persistence of chemicals is very important for risk assessment, and ready biodegradability tests are mainly conducted according to the Organisation for Economic Co-operation and Development test guideline 301C. However, the highest test concentration specified in test guideline 301C, 100 mg/L, may cause microbial toxicity and incomplete biodegradation. The authors performed test guideline 301C tests at test concentrations of 30 mg/L for 13 substances that were readily biodegradable in ready biodegradability tests but not in test guideline 301C tests. Of the 5 substances with potential to cause microbial toxicity at 100 mg/L, the percentage of biodegradation of sodium dimethyldithiocarbamate, 4-chloro-3-cresol (CC), thymol (THY), and p-tert-butyl-α-methylbenzenepropionaldehyde measured by biochemical oxygen demand (BOD) increased in the test guideline 301C test at 30 mg/L, suggesting a reduction in toxicity effects. Furthermore, CC and THY met the criteria for ready biodegradability, which are more than 60% of biodegradation by BOD and a 10-d window. Of the 8 substances with a low potential for causing microbial toxicity at 100 mg/L, the percentage of biodegradation of only 2-(diethylamino)ethanol increased in the test guideline 301C test at 30 mg/L. Employing a lower test concentration in the standard test guideline 301C test will contribute to improvement of consistency between results of a test guideline 301C test and other ready biodegradability tests. Environ Toxicol Chem 2016;35:84–90. © 2015 SETAC
The impacts of organic matter on the distribution and methylation of mercury in a hydroelectric reservoir in Wujiang River, Southwest China
Authors: Meng Bo , Feng Xinbin , Qiu Guangle , Li Zhonggen , Yao Heng , Shang Lihai , Yan Haiyu 
Published: July 2015

Abstract

To understand the impacts of organic matter on the geochemical processing of Hg in a hydroelectric reservoir, spatial and seasonal distributions of total mercury (THg) and methylmercury (MeHg) in both solid and liquid phases of sediment cores were investigated in the Wujiangdu Reservoir in Guizhou Province, China. Four sampling sites with different intensities of cage aquaculture activities were chosen and were evenly distributed from upstream to downstream of the Wujiangdu Reservoir. Elevated MeHg concentrations and the high percentage of MeHg in solid and liquid phases of the surface sediment demonstrated that the active Hg methylation process occurred downstream of the Wujiangdu Reservoir. In contrast, the absence of obvious peaks for MeHg in sediment from the upper reaches of the Wujiangdu Reservoir, consistent with low levels of organic matter, suggested that production of MeHg was limited. In sediment with high organic matter content, reduction occurred closer to the sediment surface, resulting in maximum MeHg concentration in these layers. The correlation between MeHg and organic carbon implied that organic matter content in the sediment originating from cage aquaculture activities can help to predict MeHg production rates in reservoirs, which could be used to assess possible MeHg contamination in a reservoir ecosystem. Environ Toxicol Chem 2016;35:191–199. © 2015 SETAC
Surface ocean CO2 in 1990–2011 modelled using a feed‐forward neural network
Authors: Zeng Jiye , Nojiri Yukihiro , Nakaoka Shin‐ichiro , Nakajima Hideaki , Shirai Tomoko 
Published: July 2015

This dataset includes the monthly distributions of CO2 fugacity in the world surface oceans reconstructed using a feed‐forward neural network model and the CO2 measurements of the Surface Ocean CO2 Atlas version 2.0. It has a spatial resolution of 1 × 1° and spans a period of 22 years, from January 1990 to December 2011. The dataset also includes necessary parameters for the reconstruction and an estimate of the CO2 fluxes between the ocean and the atmosphere. The aim of this work is to provide a dataset for estimating the oceans' contribution to the global carbon budget.
May the surface roughness of the retrieved femoral head influence the wear behavior of the polyethylene liner?
Authors: Taddei Paola , Tozzi Silvia , Carmignato Simone , Affatato Saverio 
Published: July 2015

AbstractThis study was aimed at determining the surface degradation occurred on retrieved ceramic and metallic heads, as well as the influence of the head surface quality on the wear of the polyethylene counterface. To this purpose, 14 ceramic and 14 metallic femoral heads retrieved at revision surgery were examined. Scanning electron microscopic analysis provided visual evidence that some metallic heads presented crescent wear more often than the ceramic ones; the former showed a higher volumetric loss (as determined by Coordinate Measuring Machine) than the latter, but less negative Rsk values. This apparent lack of correlation between volumetric loss (i.e., wear factor) and roughness data may be explained by considering that they are two temporally variant parameters. No significant differences were observed between the Ra values of the two sets of femoral heads. The cups articulating against metal heads were characterized by higher mean wear volumes than those articulating against alumina although this difference was not statistically significant; metal heads displayed significantly higher mean wear volumes than alumina heads. The micro‐Raman analysis of the cup articulated against the most worn alumina femoral head showed an orthorhombic into monoclinic phase transformation that was not observed in the cups coupled to metal heads. The obtained results showed that the surface finishing of the femoral head (in terms of Rsk values) determined the morphological changes experienced by the ultra‐high‐molecular‐weight polyethylene crystalline phase at the molecular level. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1374–1385, 2016.
Compensatory Changes in Calcium Metabolism Accompany the Loss of Vitamin D Receptor (VDR) From the Distal Intestine and Kidney of Mice
Authors: Reyes-Fernandez Perla C , Fleet James C 
Published: July 2015

ABSTRACT

1,25 Dihydroxyvitamin D3 (1,25(OH)2D) increases intestinal Ca absorption when dietary Ca intake is low by inducing gene expression through the vitamin D receptor (VDR). 1,25(OH)2D-regulated Ca absorption has been studied extensively in the small intestine, but VDR is also present in the large intestine. Our goal was to determine the impact of large intestinal VDR deletion on Ca and bone metabolism. We used transgenic mice expressing Cre-recombinase driven by the 9.5-kb human caudal type homeobox 2 (CDX2) promoter to delete floxed VDR alleles from the caudal region of the mouse (CDX2-KO). Weanling CDX2-KO mice and control littermates were fed low (0.25%) or normal (0.5%) Ca diets for 7 weeks. Serum and urinary Ca, vitamin D metabolites, bone parameters, and gene expression were analyzed. Loss of the VDR in CDX2-KO was confirmed in colon and kidney. Unexpectedly, CDX2-KO had lower serum PTH (–65% of controls, p &lt; 0.001) but normal serum 1,25(OH)2D and Ca levels. Despite elevated urinary Ca loss (eightfold higher in CDX2-KO) and reduced colonic target genes TRPV6 (–90%) and CaBPD9k (–80%) mRNA levels, CDX2-KO mice had only modestly lower femoral bone density. Interestingly, duodenal TRPV6 and CaBPD9k mRNA expression was fourfold and threefold higher, respectively, and there was a trend toward increased duodenal Ca absorption (+19%, p = 0.076) in the CDX2-KO mice. The major finding of this study is that large intestine VDR significantly contributes to whole-body Ca metabolism but that duodenal compensation may prevent the consequences of VDR deletion from large intestine and kidney in growing mice. © 2015 American Society for Bone and Mineral Research.