bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of lateral connectivity in the maintenance of macrophyte diversity and production in large rivers
Authors: Keruzoré Antoine A. , Willby Nigel J. , Gilvear David J. 
Published: October 2012

ABSTRACTLarge European river floodplains have been intensively reduced through human activities over several millennia. Ecological assessments of natural large river systems remain rare and potentially flawed since they typically omit either the main channel of the river or, more commonly, aquatic habitats that occur naturally in the floodplain of dynamic systems.Surveys were conducted over a longitudinal and lateral gradient to assess distribution, richness and production of macrophytes along two little‐disturbed large upland rivers in Scotland.Lateral dynamics, through the creation of backwaters, underpinned the occurrence, abundance and production of macrophytes in these rivers. Indeed, backwaters, despite representing only 5% of the total area of aquatic habitat, supported a significantly higher concentration of species (65% of species recorded at the riverscape scale were unique to backwaters) than the main channel.The frequency with which backwaters were connected to the main channel during flood flows influenced their species richness. Highest species richness in backwaters was typically found at low connectivity. Standing crop in backwaters was 150 times higher per unit area than in the main channel, while at the riverscape scale backwaters accounted for an average 89% of aquatic plant biomass. The highest plant biomass was found at low and medium connectivity with the main channel.Backwaters appear to be crucial habitats in maintaining macrophyte diversity and production in large river ecosystems. These results emphasize the importance of river hydrodynamics and lateral connectivity in maintaining macrophyte community diversity along large rivers. The results illustrate also the potentially very significant role of backwaters as source habitats supplying propagules and organic matter to downstream reaches.It is argued that the entire riverscape (floodplain plus main channel) must be considered in the holistic assessment of such systems, while protection of this resource requires greater recognition of linkages within and across habitats, both aquatic and terrestrial, to be effective.Copyright © 2012 John Wiley & Sons, Ltd.
Comparing Performance of Centerline Algorithms for Quantitative Assessment of Brain Vascular Anatomy
Authors: Diedrich Karl T. , Roberts John A. , Schmidt Richard H. , Parker Dennis L. 
Published: October 2012

AbstractAttributes like length, diameter, and tortuosity of tubular anatomical structures such as blood vessels in medical images can be measured from centerlines. This study develops methods for comparing the accuracy and stability of centerline algorithms. Sample data included numeric phantoms simulating arteries and clinical human brain artery images. Centerlines were calculated from segmented phantoms and arteries with shortest paths centerline algorithms developed with different cost functions. The cost functions were the inverse modified distance from edge (MDFEi), the center of mass (COM), the binary‐thinned (BT)‐MDFEi, and the BT‐COM. The accuracy of the centerline algorithms were measured by the root mean square error from known centerlines of phantoms. The stability of the centerlines was measured by starting the centerline tree from different points and measuring the differences between trees. The accuracy and stability of the centerlines were visualized by overlaying centerlines on vasculature images. The BT‐COM cost function centerline was the most stable in numeric phantoms and human brain arteries. The MDFEi‐based centerline was most accurate in the numeric phantoms. The COM‐based centerline correctly handled the “kissing” artery in 16 of 16 arteries in eight subjects whereas the BT‐COM was correct in 10 of 16 and MDFEi was correct in 6 of 16. The COM‐based centerline algorithm was selected for future use based on the ability to handle arteries where the initial binary vessels segmentation exhibits closed loops. The selected COM centerline was found to measure numerical phantoms to within 2% of the known length. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
Five examples of assessment and expression of measurement uncertainty
Authors: Possolo Antonio 
Published: October 2012

It is a long‐accepted tenet of scientific practice that every measurement result ought to include a statement of uncertainty associated with the measured value. Such uncertainty should also be propagated to functions of the measured values. It is also widely recognized that probability distributions are well suited to express measurement uncertainty and that statistical methods are the choice vehicles to produce uncertainty assessments incorporating information in empirical data as well as other relevant information, either about the quantity that is the object of measurement or about the techniques or apparatuses used in measurement.Statistical models and methods of statistical inference provide the technical machinery necessary to evaluate and propagate measurement uncertainty. Some of these models and methods are illustrated in five examples: (i) measurement of the refractive index of a glass prism (employing a venerable formula due to Gauss, as well as contemporary Monte Carlo methods); (ii) measurement of the mass fraction of arsenic in oyster tissue using data from an inter‐laboratory study (introducing a Bayesian hierarchical model with adaptive tail heaviness); (iii) measurement of the relative viscosity increment of a solution of sucrose in water (using a copula); (iv) mapping measurements of radioactivity in the area of Fukushima, Japan (via both local regression and kriging, and explaining how model uncertainty may be evaluated); and (v) combining expert opinions about the flow rate of oil during the Deepwater Horizon oil spill into the Gulf of Mexico (via linear or logarithmic pooling). Copyright © 2012 John Wiley & Sons, Ltd.
Understanding pharmacokinetic food effects using molecular dynamics simulation coupled with physiologically based pharmacokinetic modeling
Authors: Turner David C. , Yin Fuchang , Kindt James T. , Zhang Hailing 
Published: October 2012

ABSTRACTIn this study, a molecular dynamics (MD) method is assessed as a new front‐end tool for deriving relevant drug‐micelle partitioning rates for use in conjunction with a compartmental‐style gastrointestinal absorption model. A refined mechanistic approach for handling micelle‐associated vs unbound drug is presented and examined in terms of its utility for projecting human oral pharmacokinetic food/formulation effects. Similar to predecessor oral absorption models, the intestinal drug absorption rate is formulated as a function of the combined permeability through the unstirred water layer and the epithelial membrane, however, an additional diffusion coefficient adjustment is applied to account for the viscosity changes of the postprandial small intestine. Bulk passage of drug particles through the GI tract is simulated by compartmental transit through a network of nine compartments comprising the stomach, small intestine and colon. The tandem MD simulation/compartmental absorption algorithm is applied to identify factors influencing the fed vs fasted absorption ratios of a structurally diverse set of orally administered drugs. The data illustrate the interplay and apparent compromise between micelle solubilization and permeability. Copyright © 2012 John Wiley & Sons, Ltd.
Development of oral extended release formulations of 6‐hydroxybuspirone
Authors: Nicholson Sarah J. , Timmins Peter , Dockens Randy C. , Connor Alyson , Croop Robert , Ferrie Peter , Zeng Jianing , Dennis Andrew B. , Wilding Ian 
Published: October 2012

ABSTRACTReducing the maximum plasma concentration whilst maintaining the exposure was shown to ameliorate adverse events following the oral administration of 6‐hydroxybuspirone. This observation, along with a desire to provide for once daily dosing of this compound, provided the basis for the development of an extended release formulation. Hydrophilic matrix tablets based on hydroxypropyl methylcellulose and containing citric acid to provide for an acid microenvironment were prepared and evaluated by in vitro drug release studies and in vivo pharmacokinetic and scintigraphic studies using samarium oxide (153Sm) labelled dosage forms. The dosage forms were found to release the contained drug by a predominantly diffusion mechanism and the release rate was relatively independent of environmental pH. Following administration of the extended release formulations to volunteers, comparative pharmacokinetic data indicated that the extended release formulations provided for a reduction in the maximum plasma concentration of 64–70% relative to that provided by the same dose given as an oral solution, whilst maintaining exposure relative to the oral solution. By examination of absorption curves derived by Wagner‐Nelson analysis of pharmacokinetic data it was noted that drug release in vivo correlated well with drug release observed in vitro and no marked change in rate of absorption was noted when dosage forms were located in and releasing drug in the colon. The robust control of drug release seen in vitro translated to a good in vivo performance. Copyright © 2012 John Wiley & Sons, Ltd.
Development and validation of a liquid chromatography–tandem mass spectrometry method for quantitation of indomethacin in rat plasma and its application to a pharmacokinetic study in rats
Authors: S Suresh P , Dixit Abhishek , Giri Sanjeev , Rajagopal Sriram , Mullangi Ramesh 
Published: October 2012

ABSTRACTA highly sensitive and rapid bioanalytical method has been developed and validated for the estimation of indomethacin in rat plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive‐ion mode. The assay procedure involves a simple liquid–liquid extraction of indomethacin and phenacetin (internal standard, IS) from rat plasma with acetonitrile. Chromatographic separation was achieved with 0.2% formic acid–acetonitrile (25:75, v/v) at a flow rate of 0.60 mL/min on an Atlantis dC18 column with a total run time 3.0 min. The MS/MS ion transitions monitored were 357.7 → 139.1 for indomethacin and 180.20 → 110.10 for IS. Method validation and pharmacokinetic study plasma analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.51 ng/mL and the linearity was observed from 0.51 to 25.5 ng/mL. The intra‐ and inter‐day precisions were in the range of 1.00–10.2 and 5.88–9.80%, respectively. This novel method has been applied to an oral pharmacokinetic study in rats. Copyright © 2012 John Wiley & Sons, Ltd.
Meta‐stereotypes, Social Image and Help Seeking: Dependency‐Related Meta‐stereotypes Reduce Help‐Seeking Behaviour
Authors: Wakefield Juliet R. H. , Hopkins Nick , Greenwood Ronni Michelle 
Published: October 2012

ABSTRACTPeople who need help can be reluctant to seek it. This can be due to social image concerns. Here, we investigate if these concerns may be prompted by a salient negative meta‐stereotype: the belief that one's group is judged negatively by another group. Specifically, we researched group members' help‐seeking behaviour in the context of a dependency‐related meta‐stereotype. In a two‐condition study (N = 45), we manipulated participants' belief that their national group was judged dependent by a significant out‐group. We then examined their subsequent help‐seeking behaviour on a real‐world task. Participants whose social identity as a group member was salient showed greater reluctance to seek help when the meta‐stereotype was made prominent compared with when it was not. This suggests that, in a context where social image and social identity concerns are relevant, group members are willing to sacrifice the possibility of accessing needed help in order to avoid confirming a negative stereotype of their group. The implications of these results for helping transactions and community development are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
The Influence of the Internet on the Psychosocial Predictors of Collective Action
Authors: Alberici Augusta Isabella , Milesi Patrizia 
Published: October 2012

ABSTRACTThe Internet has emerged as an important communication platform for the support of collective action, but little is known about how it influences the psychosocial motives for participation. Two quantitative studies were conducted within two different mobilizing contexts, in which offline collective actions were launched through computer‐mediated communication. We examined whether and how the frequency with which people participated in online political discussions moderated the effects of the psychosocial predictors of collective action, specifically politicized identity, anger, collective efficacy, and morality. Results showed that collective action intention was predicted by politicized identity only when participants reported a higher versus lower frequency of online discussion. However, anger did not predict collective action when people had the chance to express this emotion through a higher versus lower frequency of online discussion. Moreover, collective efficacy and morality supported collective action intention in participants who reported a higher versus lower frequency of online discussion. We theorize on how computer‐mediated communication, and its specific features, can be studied as a mobilizing context that influences the psychosocial motives to participate in collective action. Copyright © 2012 John Wiley & Sons, Ltd.
One‐Pot Conversion of Inulin to Furan Derivatives Catalyzed by Sulfated TiO2/Mordenite Solid Acid
Authors: Shen X. , Wang Y. X. , Hu C. W. , Qian K. , Ji Z. , Jin M. 
Published: October 2012

AbstractWe prepared a sulfated TiO2/mordenite solid acid for the heterogeneous catalytic conversion of inulin (polysaccharide) to 5‐hydroxymethylfurfural and 2,5‐furancarboxaldehyde. The hydrolysis of inulin and the dehydration of fructose were performed by using a one‐pot method in a water/2‐butanol biphasic system. With an inulin conversion rate of 82.3 %, a high 5‐hydroxymethylfurfural yield of 61.5 % was obtained, which represents moderate catalytic reactivity and selectivity but facilitates the separation process comprehensively. The catalytic performance was attributed to the SO42− groups and the Lewis acid sites on the titania surfaces. A delicate loading rate of titania over mordenite was critical to maintain sufficient active sites, whereas an appropriate porosity of the complex system was reserved for the diffusion of reactants and products.
Selective Catalytic Oxidation of CH Bonds with Molecular Oxygen
Authors: Roduner Emil , Kaim Wolfgang , Sarkar Biprajit , Urlacher Vlada B. , Pleiss Jürgen , Gläser Roger , Einicke Wolf‐Dietrich , Sprenger Georg A. , Beifuß Uwe , Klemm Elias , Liebner Christian , Hieronymus Hartmut , Hsu Shih‐Fan , Plietker Bernd , Laschat Sabine 
Published: October 2012

AbstractAlthough catalytic reductions, cross‐couplings, metathesis, and oxidation of CC double bonds are well established, the corresponding catalytic hydroxylations of CH bonds in alkanes, arenes, or benzylic (allylic) positions, particularly with O2, the cheapest, “greenest”, and most abundant oxidant, are severely lacking. Certainly, some promising examples in homogenous and heterogenous catalysis exist, as well as enzymes that can perform catalytic aerobic oxidations on various substrates, but these have never achieved an industrial‐scale, owing to a low space‐time‐yield and poor stability. This review illustrates recent advances in aerobic oxidation catalysis by discussing selected examples, and aims to stimulate further exciting work in this area. Theoretical work on catalyst precursors, resting states, and elementary steps, as well as model reactions complemented by spectroscopic studies provide detailed insight into the molecular mechanisms of oxidation catalyses and pave the way for preparative applications. However, O2 also poses a safety hazard, especially when used for large scale reactions, therefore sophisticated methodologies have been developed to minimize these risks and to allow convenient transfer onto industrial scale.
Organic Dye‐Photocatalyzed Acylnitroso Ene Reaction
Authors: Teo Yew Chin , Pan Yuanhang , Tan Choon Hong 
Published: October 2012

AbstractRose bengal, an inexpensive and readily available organic dye, is demonstrated to be a photoredox catalyst for the formation of transient acylnitroso intermediates under visible light irradiation. This method is operationally simple and uses air as the terminal oxidant. Reactions of acylnitroso with a range of functionalized alkenes give intermolecular acylnitroso ene products in moderate to good yields. This is an environmentally friendly allylic amination methodology that avoids the use of metal catalysts and stoichiometric amount of oxidants. A plausible reaction mechanism is proposed on the basis of singlet oxygen and fluorescence quenching studies.
Phosphine Organocatalysis in the Synthesis of Natural Products and Bioactive Compounds
Authors: Gomez Catherine , Betzer Jean‐François , Voituriez Arnaud , Marinetti Angela 
Published: October 2012

AbstractDuring the last few years, synthetic methods based on phosphine organocatalysis have experienced extremely fast developments. This short overview is intended to demonstrate that these methods can afford suitable tools for the constitution of either focused or diversity‐oriented‐synthesis (DOS) inspired libraries of small molecules for biological screening. It also reports selected examples where these organocatalytic methods have been used conveniently as key steps in the formal or total synthesis of complex natural products. Especially, synthetic applications of the inter‐ and intramolecular cyclizations of unsaturated substrates have been considered in this review.
Quaternary Chiral β2,2‐Amino Acids with Pyridinium and Imidazolium Substituents
Authors: Mata Lara , Avenoza Alberto , Busto Jesús H. , Corzana Francisco , Peregrina Jesús M. 
Published: October 2012

AbstractThe reactions of cyclic sulfamidates as electrophiles with a variety of nitrogen‐containing aromatic heterocycle nucleophiles, such as pyridines, N‐alkylimidazoles and N‐methylbenzimidazol, was explored. In all cases, although the nucleophilic substitution reactions occurred on quaternary centres, elimination products were not detected. The inversion of configuration at this quaternary centre was determined by X‐ray diffraction analysis and the enantiomeric excess of the reactions was checked by chiral HPLC. This synthetic approach allowed us to obtain a new family of chiral charged β2,2‐amino acids, including a new bisamino acid that incorporates an imidazolium salt as a cross‐linker. In this context, the treatment of these chiral imidazolium salts with Ag2O opens the way to new chiral N‐heterocyclic carbenes, which are important substrates in the fields of organometallic and organocatalytic chemistry. Additionally, we have done a thorough conformational analysis of these β‐amino acid derivatives, both in the solid state and in solution. The most important conformational feature of these acyclic systems is the rigidity of the N‐CH2‐C‐N+ dihedral angle, which is essentially due to the gauche effect.
Thermodynamic and Mechanistic Insights into Translesion DNA Synthesis Catalyzed by Y‐Family DNA Polymerase Across a Bulky Double‐Base Lesion of an Antitumor Platinum Drug
Authors: Brabec Viktor , Malina Jaroslav , Margiotta Nicola , Natile Giovanni , Kasparkova Jana 
Published: October 2012

AbstractTo determine how the Y‐family translesion DNA polymerase η (Polη) processes lesions remains fundamental to understanding the molecular origins of the mutagenic translesion bypass. We utilized model systems employing a DNA double‐base lesion derived from 1,2‐GG intrastrand cross‐links of a new antitumor PtII complex containing a bulky carrier ligand, namely [PtCl2(cis‐1,4‐dach)] (DACH=diaminocyclohexane). The catalytic efficiency of Polη for the insertion of correct dCTP, with respect to the other incorrect nucleotides, opposite the 1,2‐GG cross‐link was markedly reduced by the DACH carrier ligand. This reduced efficiency of Polη to incorporate the correct dCTP could be due to a more extensive DNA unstacking and deformation of the minor groove induced in the DNA by the cross‐link of bulky [PtCl2(cis‐1,4‐dach)]. The major products of the bypass of this double‐base lesion produced by [PtCl2(cis‐1,4‐dach)] by Polη resulted from misincorporation of dATP opposite the platinated G residues. The results of the present work support the thesis that this misincorporation could be due to sterical effects of the bulkier 1,4‐DACH ligand hindering the formation of the Polη–DNA–incoming nucleotide complex. Calorimetric analysis suggested that thermodynamic factors may contribute to the forces that governed enhanced incorporation of the incorrect dATP by Polη as well.
Enantiomerization Mechanism of Thalidomide and the Role of Water and Hydroxide Ions
Authors: Tian Chuanjin , Xiu Peng , Meng Yan , Zhao Wenyan , Wang Zhigang , Zhou Ruhong 
Published: October 2012

AbstractThe significance of the molecular chirality of drugs has been widely recognized due to the thalidomide tragedy. Most of the new drugs reaching the market today are single enantiomers, rather than racemic mixtures. However, many optically pure drugs, including thalidomide, undergo enantiomerization in vivo, thus negating the single enantiomers’ benefits or inducing unexpected effects. A detailed atomic level understanding of chiral conversion, which is still largely lacking, is thus critical for drug development. Herein, we use first‐principle density function theory (DFT) to explore the mechanism of enantiomerization of thalidomide. We have identified the two most plausible interconversion pathways for isolated thalidomide: 1) proton transfer from the chiral carbon center to an adjacent carbonyl oxygen atom, followed by isomerization and rotation of the glutarimide ring (before the proton hops back to the chiral carbon atom); and 2) a pathway that is the same as “1”, but with the isomerization of the glutarimide ring occurring ahead of the initial proton transfer reaction. There are two remarkable energy barriers, 73.29 and 23.59 kcal mol−1, corresponding to the proton transfer and the rotation of the glutarimide ring, respectively. Furthermore, we found that water effectively catalyzes the interconversion by facilitating the proton transfer with the highest energy barrier falling to approximately 30 kcal mol−1, which, to our knowledge, is the first time that this important role of water in chiral conversion has been demonstrated. Finally, we show that the hydroxide ion can further lower the enantiomerization energy barrier to approximately 24 kcal mol−1 by facilitating proton abstraction, which agrees well with recent experimental data under basic conditions. Our current findings highlight the importance of water and hydroxide ions in the enantiomerization of thalidomide and also provide new insights into the mechanism of enantiomerization at an atomic level.