bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the Glutathione Peroxidase‐Like Activity of a Cyclic Seleninate by DFT and Solvent‐Assisted Proton Exchange
Authors: Bayse Craig A. , Ortwine Kristine N. 
Published: June 2013

AbstractThe mechanism of redox scavenging of a highly active cyclic seleninate was modeled by using density functional theory and solvent‐assisted proton exchange (SAPE), a method of microsolvation intended to mimic the role of the solvent in proton‐transfer reactions. Models of the proposed mechanism suggest that a pathway to a selenenyl sulfide, a possible dead‐end intermediate, is favored over regeneration of the seleninate catalyst. Alternate pathways through selenurane intermediates and a cyclic selenenate also appear to lead to the selenenyl sulfide. Based upon the DFT‐SAPE results, we suggest that the high level of catalysis shown by the cyclic seleninate may be attributed to experimental reaction conditions, in which the excess oxidant ensures that the catalytic cycle bypasses the selenenyl sulfide. Catalysis under less oxidizing conditions are proposed to occur through oxidation of the selenenyl sulfide to the seleninyl sulfide.
A Flexible Strategy Towards Thienyl‐, Oxazolyl‐ and Pyridyl‐Fused Fluorenones
Authors: Souibgui Amel , Gaucher Anne , Marrot Jérôme , Aloui Faouzi , Mahuteau‐Betzer Florence , Ben Hassine Bechir , Prim Damien 
Published: June 2013

AbstractThe preparation of new thienyl‐, oxazolyl‐, and pyridyl‐fused benzo[c]fluorenones has been developed from a unique and easily available common precursor. Starting from bromotetralone, a short sequence allowed the construction of various heterocycles followed by Suzuki coupling and final acid‐promoted formation of the central cyclopentanone unit. The flexible strategy allowed the selective preparation of fused penta‐ to hepta‐cyclic architectures. Fully aromatic targets have been obtained through the application of an oxidation process. The influence of structural modulations on the photophysical properties are described.
A soil quality index for reclaimed mine soils
Authors: Asensio Verónica , Guala S.D. , Vega Flora A. , Covelo Emma F. 
Published: June 2013

Abstract

The quality of soils found in mines is low if they do not receive any reclamation treatment; yet, to the authors' knowledge, there are still no equations to evaluate the quality of metal-contaminated mine soils after the application of the most widely used reclamation treatments (planting vegetation and amending with wastes). Therefore, the purposes of the present study were 1) to propose a method for developing soil quality indexes (SQIs); 2) to develop the SQIs for 2 types of mine soils (settling pond and mine tailing) reclaimed by planting trees, amending with wastes, or both; and 3) to assess the quality of these soils under field conditions. The results obtained after the use of an SQI developed for reclaimed mine soils through the selection of an SQI with a factor analysis and the totaling of the scores of the selected variables revealed that this method is a valid tool for developing SQIs. Applying this index with reclaimed mine soils showed that the untreated sites had a very low quality and that the treatment that most improved the soils was amending with wastes (sewage sludges and paper mill residues). The authors recommend the periodic addition of sewage sludges and paper mill residues to degraded sites as they increase the quality of soils, but the effects decrease over time. Environ Toxicol Chem 2013;32:2240–2248. © 2013 SETAC
Medium-chain chlorinated paraffins (MCCPs): A review of bioaccumulation potential in the aquatic environment
Authors: Thompson Roy , Vaughan Martin 
Published: June 2013

Abstract
Chlorinated paraffins (CPs) are high molecular weight organochlorine compounds that have been used in a variety of industrial applications for many years. Medium-chain chlorinated paraffins (MCCPs) (CAS 85535-85-9; Alkanes, C14–17, chloro) are currently under investigation as potential persistent bioaccumulative toxic (PBT) compounds. In this article, the bioaccumulation potential of MCCPs is assessed using a tiered framework proposed after a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop in 2008. The framework proposes the use of physicochemical properties and modeling assessment, bioconcentration/bioaccumulation (BCF/BAF) assessment, biomagnification (BMF) assessment, and trophic magnification factor (TMF) assessment. It is hoped that use of this framework could harmonize and improve the efficiency and effectiveness of the chemical substance evaluation screening process for PBT properties. When applied to MCCPs, the following conclusions were made: empirical physiochemical data is available negating the use of models; laboratory BCFs range from 1000 to 15 000 (growth-corrected lipid normalized values) for 2 MCCP structures; field BAFs were an order of magnitude higher than the trigger criterion for “B status possible”; although results may not meet acceptance criteria for field studies, laboratory-derived BMFs for a number of C14–17 chlorinated alkanes were less than the trigger value of 1 (based on whole-body concentrations) whereas field-derived BMFs were less than 1 (based on lipid corrected values [generally used for field data] excluding one measure for sculpin, [Cottus cognatus]-Diporeia that was based on only one detectable sample); and finally, TMFs were less than the trigger criterion value of 1, which are considered the most convincing evidence for bioaccumulative properties of a compound and the “Gold Standard” measure of bioaccumulation. This article also discusses the uncertainties surrounding the published data, especially concerning field data where limited sampling points are available and the difficulty in assessing the bioaccumulative potential of MCCPs as mixtures of different congeners. In conclusion, although some laboratory bioaccumulation values have a potential for concern, the majority of field values are more favorable when assessing the bioaccumulative potential of MCCPs. Definitive conclusions on the PBT assessment of MCCPs can be eased with further testing in both areas of P and B in the laboratory in conjunction with further monitoring of biota in the field to derive more robust field data. Integr Environ Assess Manag 2014;10:78–86. © 2013 SETAC
Spending more, doing more, or both? An alternative method for quantifying utilization during hospitalizations
Authors: Lagu Tara , Krumholz Harlan M. , Dharmarajan Kumar , Partovian Chohreh , Kim Nancy , Mody Purav S. , Li Shu‐Xia , Strait Kelly M. , Lindenauer Peter K. 
Published: June 2013

BACKGROUNDBecause relative value unit (RVU)‐based costs vary across hospitals, it is difficult to use them to compare hospital utilization.OBJECTIVETo compare estimates of hospital utilization using RVU‐based costs and standardized costs.DESIGNRetrospective cohort.SETTING AND PATIENTSYears 2009 to 2010 heart failure hospitalizations in a large, detailed hospital billing database that contains an itemized log of costs incurred during hospitalization.INTERVENTIONWe assigned every item in the database with a standardized cost that was consistent for that item across all hospitals.MEASUREMENTSStandardized costs of hospitalization versus RVU‐based costs of hospitalization.RESULTSWe identified 234 hospitals with 165,647 heart failure hospitalizations. We observed variation in the RVU‐based cost for a uniform “basket of goods” (10th percentile cost $1,552; 90th percentile cost of $3,967). The interquartile ratio (Q75/Q25) of the RVU‐based costs of a hospitalization was 1.35 but fell to 1.26 after costs were standardized, suggesting that the use of standardized costs can reduce the “noise” due to differences in overhead and other fixed costs. Forty‐six (20%) hospitals had reported costs of hospitalizations exceeding standardized costs (indicating that reported costs inflated apparent utilization); 42 hospitals (17%) had reported costs that were less than standardized costs (indicating that reported costs underestimated utilization).CONCLUSIONSStandardized costs are a novel method for comparing utilization across hospitals and reduce variation observed with RVU‐based costs. They have the potential to help hospitals understand how they use resources compared to their peers and will facilitate research comparing the effectiveness of higher and lower utilization. Journal of Hospital Medicine 2013;8:373–379. © 2013 Society of Hospital Medicine
Enhancing the Superhydrophobic State Stability of Chitosan‐Based Coatings for Textiles
Authors: Ivanova Nina A. , Rutberg Galina I. , Philipchenko Anatoly B. 
Published: June 2013

AbstractA superhydrophobic textile for biomedical applications is designed using chitosan‐based hydrophobic nanoparticles. The fabrication of nanoparticles is based on the electrostatic interaction between the amine group of chitosan and the negatively charged fluoroanion. The coating is formed by spraying the nanoparticles dispersion over the textile surface, while the complementary hydrophobization by functionalized perfluorodecylsilane leads to substitution of hydrophilic surface groups by hydrophobic ones. The crucial role of the relative number of fluoroanions per elementary unit of chitosan in both surface wettability and durability of coatings in contact with aqueous media is demonstrated.
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Interaction of polymorphisms in mitotic regulator genes with cigarette smoking and pancreatic cancer risk
Authors: Jang Ji‐Hyun , Cotterchio Michelle , Borgida Ayelet , Liu Geoffrey , Gallinger Steven , Cleary Sean P. 
Published: June 2013

AbstractMitotic regulator genes have been associated with several cancers, however little is known about their possible association with pancreatic cancer. Smoking and family history are the strongest risk factors for this highly fatal disease. The main purpose of this study was to determine if polymorphisms of mitotic regulator genes are associated with pancreatic cancer and whether they modify the association between cigarette smoking and pancreatic cancer risk. A population‐based case‐control study was conducted in Ontario with 455 pathology‐confirmed pancreatic cancer cases and 893 controls. Cigarette smoking history was collected using questionnaires and DNA obtained from blood samples. Genotypes were determined by mass‐spectrometry. Odds ratio estimates were obtained using multivariate logistic regression. Interactions between genetic variant and smoking were assessed using stratified analyses and the likelihood ratio statistic (significance P < 0.05). Variants of MCPH1, FYN, APC, PRKCA, NIN, TopBP1, RIPK1, and SNW1 were not independently associated with pancreatic cancer risk. A significant interaction was observed between pack‐years and MCPH1‐2550‐C > T (P = 0.02). Compared to never smokers, individuals with 10–27 pack‐years and MCPH1‐2550‐CC genotype were at increased risk for pancreatic cancer (MVOR = 2.49, 95% confidence interval [95% CI]: 1.55, 4.00) as were those with >27 pack‐years and MCPH1‐2550‐TC genotype (MVOR = 2.42, 95% CI: 1.45, 4.05). A significant interaction was observed between smoking status and TopBP1‐3257‐A > G (P = 0.04) using a dominant model. Current smokers with the TopBP1‐3257 A allele were at increased risk for pancreatic cancer (MVOR = 2.55, 95% CI: 1.77, 3.67). MCPH1‐2550‐C > T and TopBP1‐3257‐A > G modify the association between smoking and pancreatic cancer. These findings provide insights into the potential molecular mechanisms behind smoking‐associated pancreatic cancer. © 2013 Wiley Periodicals, Inc.
Robust shortest path problems with two uncertain multiplicative cost coefficients
Authors: Kwon Changhyun , Lee Taehan , Berglund Paul 
Published: June 2013

AbstractWe consider a robust shortest path problem when the cost coefficient is the product of two uncertain factors. We first show that the robust problem can be solved in polynomial time by a dual‐variable enumeration with shortest path problems as subproblems. We also propose a path enumeration approach using a K ‐shortest paths finding algorithm that may be efficient in many real cases. An application in hazardous materials transportation is discussed, and the solution methods are illustrated by numerical examples. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013
Multigrid transfers for nonsymmetric systems based on Schur complements and Galerkin projections
Authors: Wiesner T. A. , Tuminaro R. S. , Wall W. A. , Gee M. W. 
Published: June 2013

SUMMARYA framework is proposed for constructing algebraic multigrid transfer operators suitable for nonsymmetric positive definite linear systems. This framework follows a Schur complement perspective as this is suitable for both symmetric and nonsymmetric systems. In particular, a connection between algebraic multigrid and approximate block factorizations is explored. This connection demonstrates that the convergence rate of a two‐level model multigrid iteration is completely governed by how well the coarse discretization approximates a Schur complement operator. The new grid transfer algorithm is then based on computing a Schur complement but restricting the solution space of the corresponding grid transfers in a Galerkin‐style so that a far less expensive approximation is obtained. The final algorithm corresponds to a Richardson‐type iteration that is used to improve a simple initial prolongator or a simple initial restrictor. Numerical results are presented illustrating the performance of the resulting algebraic multigrid method on highly nonsymmetric systems. Copyright © 2013 John Wiley & Sons, Ltd.
A path towards a better characterisation of silicon thin‐film solar cells: depth profile analysis by pulsed radiofrequency glow discharge optical emission spectrometry
Authors: Sanchez Pascal , Fernández Beatriz , Menéndez Armando , Gómez David , Pereiro Rosario , Sanz‐Medel Alfredo 
Published: June 2013

ABSTRACTThe analytical potential of radiofrequency pulsed glow discharge optical emission spectrometry (rf‐PGD‐OES) is investigated for quantitative depth profiling analysis of thin‐film solar cells (TFSC) based on hydrogenated amorphous silicon (a‐Si:H). This method does not require sampling at ultra‐high‐vacuum conditions, and so it facilitates higher sample throughput than do reference techniques. In this paper, the determination of compositional depth profiles of a‐Si:H TFSC was performed by resorting to a multi‐matrix calibration procedure. For this purpose, certified reference materials, as well as laboratory standards based on individual layers of doped a‐Si:H, were simultaneously employed to build the analytical calibration curves. Results show that rf‐PGD‐OES allows us to discriminate the different layers of photovoltaic devices: the front contact composed by ZnO:Al2O3 (AZO), the a‐Si:H layer (the B‐doped, intrinsic a‐Si:H and P‐doped films), the AZO/Al back contact and substrate. A good agreement with the nominal values for element concentrations (e.g. 0.4% of H, 1.5% of B and 3.7% of P) and layer thicknesses (in the range of 950 nm for the front contact and 13 nm for the P‐doped a‐Si:H layer) was obtained, demonstrating the ability of rf‐PGD‐OES for a direct, sensitive and high‐depth‐resolution analysis of photovoltaic devices. Moreover, diffusion processes between the coating layers, which could have an important influence on the final efficiency of TFSC, can be identified as well. Hence, the findings support the use of rf‐PGD‐OES as an analysis method in the development of photovoltaic thin films. Copyright © 2013 John Wiley & Sons, Ltd.
Air‐stable copper derivatives as efficient catalysts for controlled lactide polymerization: Facile synthesis and characterization of well‐defined benzotriazole phenoxide copper complexes
Authors: Li Chen‐Yu , Hsu Shi‐Jie , Lin Chin‐lung , Tsai Chen‐Yen , Wang Jun‐Han , Ko Bao‐Tsan , Lin Chia‐Her , Huang Hsi‐Ya 
Published: June 2013

ABSTRACTAir‐stable copper catalysts supported by bis‐BTP ligands (BTP = N,O‐bidentate benzotriazole phenoxide) were synthesized and structurally characterized. The reactions of Cu(OAc)2·H2O with 2.0 molar equivalents of sterically bulky 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐bis(1‐methyl‐1‐phenylethyl)phenol (CMe2PhBTP‐H) and 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐di‐tert‐butylphenol (t‐BuBTP‐H) in refluxing ethanol solution afforded monomeric copper complexes [(CMe2PhBTP)2Cu] (1) and [(t‐BuBTP)2Cu] (2), respectively. The four‐coordinated copper analogue [(TMClBTP)2Cu] (3) resulted from treatment of 2‐tert‐butyl‐6‐(5‐chloro‐2H‐benzotriazol‐2‐yl)‐4‐methylphenol (TMClBTP‐H) as the ligand under the same synthetic method with ligand to metal precursor ratio of 2:1, but treatment of complex 3 in acetone gave five‐coordinated monomeric complex [(TMClBTP)2Cu(Me2CO)] (4). X‐ray diffraction of single crystals indicates that Cu complex 4 assumes a distorted square pyramidal geometry, penta‐coordinated by two BTP ligands, and one Me2CO molecule. Catalysis for lactide (LA) polymerization of BTP‐containing Cu complexes in the presence of various alcohol initiators was investigated. Complex 3 initiated by 9‐anthracenemethanol catalyzes the ring‐opening polymerization effectively not only in a “living” fashion but also in an “immortal” manner, yielding polymers with the predictable molecular weights and narrow molecular weight distributions. Initiations from multifunctional alcohols were able to produce PLLAs with two‐arm linear and three‐arm star‐shaped molecular architectures. The controlled character of Cu complex 3 also enabled us to synthesize the PEG‐b‐PLLA copolymer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3840–3849
Calibrations for measurement of manganese and zinc in nail clippings using portable XRF
Authors: Fleming David E. B. , Gherase Mihai R. , Anthonisen Madeleine 
Published: June 2013

A calibration method was developed to assess elemental concentrations in nail clippings, using a portable X‐ray fluorescence (XRF) device. Specifically, manganese and zinc were investigated in this study. Two sets of phantom nail clipping samples were prepared, one set containing manganese and one set containing zinc. In both sets, elemental concentrations in the phantom clippings were varied from 10 to 50 µg/g, in increments of 10 µg/g. Additionally, for each concentration, five distinct masses of sample were prepared ranging from 20 to 100 mg, in increments of 20 mg. XRF spectrometry was performed with the various samples using a portable X‐ray tube and detector system.Kα characteristic X‐rays were detected for both manganese and zinc. Intensities of detection were plotted against added concentration, resulting in linear relationships for both manganese and zinc. The slopes of these calibration lines were then examined as a function of sample mass. An empirical function was fit to the slope–mass relationship and compared with those obtained previously from other elements. By using this XRF calibration approach, it is possible to estimate elemental concentrations in human nail clippings for a variety of elements of medical interest. Copyright © 2013 John Wiley & Sons, Ltd.
Synthesis, Crystal Structures, and Magnetic Properties of Two Tetrahedral MnIIMnIII3 Complexes
Authors: Yang Pei‐Pei , Zhu Li‐Li , Xu Yun , Shao Cong‐Ying 
Published: June 2013

AbstractTwo tetranuclear manganese complexes, [NaMnIIMn3III(μ4‐O2–)(HL)3(SCN)4] (1) and [NaMnIIMn3III(μ4‐O2–)(HL)3Cl4][NaMnIIMn3III(μ4‐O2–)(HL)3Cl3(H2O)]ClO4·3.5H2O (2) were obtained from the reaction of manganese perchlorate with a quadridentate Schiff base ligand, 3‐(2‐hydroxybenzylideneamino)propane‐1, 2‐diol (H3L) derived from condensation of 2‐hydroxybenzaldehyde with 3‐amino‐1, 2‐propanediol, as well as the coligand KSCN or NaCl under basic conditions. Single‐crystal X‐ray studies reveal that those two complexes all have a mixed‐valent tetrahedral core, which contains an apical MnII ion and three basal MnIII ions situated in the [Mn3(μ4‐O2–)]7+ equilateral triangle plane. Fitting of the magnetic susceptibility data to the theoretical χmT vs. T expression, revealed that the presence of only antiferromagnetic interactions between the central metal atoms in 1, while both antiferromagnetic and ferromagnetic interactions are present in 2.
Cobalt(II)‐Terephthalate Frameworks Containing Bis(benz­imidazole) Derivative Co‐ligands: Syntheses, Crystal Structures, Catalytic and Fluorescence Properties
Authors: Xiao Shu‐Lin , Qin Li , Ma Pei‐Juan , Cui Guang‐Hua 
Published: June 2013

AbstractTwo metal‐organic coordination polymers of CoII with the molecular formulae [Co(L1)(tp)(H2O)2]n (1) and [Co(L2)(tp)·H2O]n (2) [L1 = 1, 4‐bis(benzimidazole‐1‐ylmethyl)‐ benzene; L2 = 1, 1‐(1, 4‐butanediyl)bis(5, 6‐dimethylbenzimidazole); tp = terephthalate] were synthesized and characterized by single‐crystal X‐ray diffraction studies, infrared spectroscopy (IR), thermogravimetric analysis (TGA), X‐ray powder diffraction (XRPD), and elemental analysis. The structure determination of complex 1 reveals a 2D layer with (4, 4) topology, with CoII ions at the nodes connected through tp and L1 co‐ligands. Complex 2 is the first example of a four‐connected SrAl2 structure type (sra, 42638 topology) with threefold interpenetration in CoII coordination frameworks, forming by bridging L2 and tp co‐ligands. In addition, the fluorescence and catalytic performances of the complexes for the degradation of methyl orange were investigated.
Subcortical Neural Synchrony and Absolute Thresholds Predict Frequency Discrimination Independently
Authors: Marmel F. , Linley D. , Carlyon R. P. , Gockel H. E. , Hopkins K. , Plack C. J. 
Published: June 2013

AbstractThe neural mechanisms of pitch coding have been debated for more than a century. The two main mechanisms are coding based on the profiles of neural firing rates across auditory nerve fibers with different characteristic frequencies (place-rate coding), and coding based on the phase-locked temporal pattern of neural firing (temporal coding). Phase locking precision can be partly assessed by recording the frequency-following response (FFR), a scalp-recorded electrophysiological response that reflects synchronous activity in subcortical neurons. Although features of the FFR have been widely used as indices of pitch coding acuity, only a handful of studies have directly investigated the relation between the FFR and behavioral pitch judgments. Furthermore, the contribution of degraded neural synchrony (as indexed by the FFR) to the pitch perception impairments of older listeners and those with hearing loss is not well known. Here, the relation between the FFR and pure-tone frequency discrimination was investigated in listeners with a wide range of ages and absolute thresholds, to assess the respective contributions of subcortical neural synchrony and other age-related and hearing loss-related mechanisms to frequency discrimination performance. FFR measures of neural synchrony and absolute thresholds independently contributed to frequency discrimination performance. Age alone, i.e., once the effect of subcortical neural synchrony measures or absolute thresholds had been partialed out, did not contribute to frequency discrimination. Overall, the results suggest that frequency discrimination of pure tones may depend both on phase locking precision and on separate mechanisms affected in hearing loss.