bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scaling the Velocity Gradients in a Vessel Agitated by a Rushton Turbine
Authors: Šulc Radek , Ditl Pavel 
Published: January 2017

AbstractScaling of fluctuation velocity gradients was investigated in a vessel agitated by a Rushton turbine. By using turbulence spectrum analysis, it was derived that, for high Reynolds numbers, the squared dimensionless local fluctuation velocity gradient is proportional to the squared impeller Reynolds number. This theoretical prediction was tested on experimental data in the range Re = 50 000 – 110 556. The calculated isotropy ratios are independent of the impeller Reynolds number, and their inter‐ratios depend on the ratio of the axial and the radial components of the fluctuation velocity. The experiments also support the idea that the isotropy ratios differ from zone to zone in an agitated vessel.
Aliphatic C−C Bond Cleavage in α‐Hydroxy Ketones by a Dioxygen‐Derived Nucleophilic Iron–Oxygen Oxidant
Authors: Bhattacharya Shrabanti , Rahaman Rubina , Chatterjee Sayanti , Paine Tapan K. 
Published: January 2017

AbstractA nucleophilic iron–oxygen oxidant, formed in situ in the reaction between an iron(II)–benzilate complex and O2, oxidatively cleaves the aliphatic C−C bonds of α‐hydroxy ketones. In the cleavage reaction, α‐hydroxy ketones without any α‐C−H bond afford a 1:1 mixture of carboxylic acid and ketone. Isotope labeling studies established that one of the oxygen atoms from dioxygen is incorporated into the carboxylic acid product. Furthermore, the iron(II) complex cleaves an aliphatic C−C bond of 17‐α‐hydroxyprogesterone affording androstenedione and acetic acid. The O2‐dependent aliphatic C−C bond cleavage of α‐hydroxy ketones containing no α‐C−H bond bears similarity to the lyase activity of the heme enzyme, cytochrome P450 17A1 (CYP17A1).
NiNbO catalyst deposited on anodized aluminum monoliths for the oxidative dehydrogenation of ethane
Authors: Santander José A. , Boldrini Diego E. , Pedernera Marisa N. , Tonetto Gabriela M. 
Published: January 2017

AbstractAluminum monoliths were used as substrates to prepare structured catalysts. A rough alumina layer was generated on the surface of the substrates by anodizing followed by hydrothermal treatments. The dip‐coating technique was used for coating the monolithic substrates. Aqueous suspensions with 0.15 and 0.30 g/g of Ni‐Nb mixed oxides catalysts were prepared for that purpose. Colloidal SiO2 was added as a binder in order to obtain homogeneous and adherent coatings. The samples were characterized by SEM, TPR, XPS, XRD, and N2 adsorption and tested in the oxidative dehydrogenation (ODH) of ethane to ethylene. The silica particles produced a drop in catalytic activity without affecting ethylene selectivity. The former effect was attributed mainly to a decrease in surface nickel concentration and an increase in reduction temperature. The presence of anodized aluminum substrates in the reaction environment did not have a significant influence on catalytic activity and product distribution, as observed for the coated monoliths used in this work, thus being a useful material to prepare structured catalysts for low‐temperature ethane ODH.
Structural Basis of the Interaction of Cyclin‐Dependent Kinase 2 with Roscovitine and Its Analogues Having Bioisosteric Central Heterocycles
Authors: Nekardová Michaela , Vymětalová Ladislava , Khirsariya Prashant , Kováčová Silvia , Hylsová Michaela , Jorda Radek , Kryštof Vladimír , Fanfrlík Jindřich , Hobza Pavel , Paruch Kamil 
Published: January 2017

AbstractThe structural basis for the interaction of roscovitine and analogues containing 13 different bioisosteric central heterocycles with the enzyme cyclin‐dependent kinase 2 (CDK2) is elucidated. Although all the central scaffolds are very similar to the purine core of roscovitine, the experimentally determined IC50 values of the inhibitors span three orders of magnitude. By using an extensive computational chemistry approach, the affinities of the inhibitors to CDK2 are determined as calculated binding scores of complexes of the inhibitors with the protein. The interactions of the inhibitors with CDK2 are computationally described by using a hybrid quantum mechanics/semi‐empirical quantum mechanics method (QM/SQM), which combines the DFT‐D method for the QM part and the PM6‐D3H4X method for the SQM part. The solvent effect is described by the COSMO implicit solvation model at the SQM level for the whole system. The contributions of the scaffolds and the individual substituents, quantified and evaluated in relation to conformations of optimized protein–inhibitor complexes, are found not to be simply additive. The inhibitory activity of the selected candidates, including two newly prepared compounds, is tested against CDK2. The results of the calculations are in close agreement with the experimental data.
Can community structure track sea‐level rise? Stress and competitive controls in tidal wetlands
Authors: Schile Lisa M. , Callaway John C. , Suding Katharine N. , Kelly N. Maggi 
Published: January 2017

AbstractClimate change impacts, such as accelerated sea‐level rise, will affect stress gradients, yet impacts on competition/stress tolerance trade‐offs and shifts in distributions are unclear. Ecosystems with strong stress gradients, such as estuaries, allow for space‐for‐time substitutions of stress factors and can give insight into future climate‐related shifts in both resource and nonresource stresses. We tested the stress gradient hypothesis and examined the effect of increased inundation stress and biotic interactions on growth and survival of two congeneric wetland sedges, Schoenoplectus acutus and Schoenoplectus americanus. We simulated sea‐level rise across existing marsh elevations and those not currently found to reflect potential future sea‐level rise conditions in two tidal wetlands differing in salinity. Plants were grown individually and together at five tidal elevations, the lowest simulating an 80‐cm increase in sea level, and harvested to assess differences in biomass after one growing season. Inundation time, salinity, sulfides, and redox potential were measured concurrently. As predicted, increasing inundation reduced biomass of the species commonly found at higher marsh elevations, with little effect on the species found along channel margins. The presence of neighbors reduced total biomass of both species, particularly at the highest elevation; facilitation did not occur at any elevation. Contrary to predictions, we documented the competitive superiority of the stress tolerator under increased inundation, which was not predicted by the stress gradient hypothesis. Multifactor manipulation experiments addressing plant response to accelerated climate change are integral to creating a more realistic, valuable, and needed assessment of potential ecosystem response. Our results point to the important and unpredicted synergies between physical stressors, which are predicted to increase in intensity with climate change, and competitive forces on biomass as stresses increase.
Forest cover change and water yield in large forested watersheds: A global synthetic assessment
Authors: Li Qiang , Wei Xiaohua , Zhang Mingfang , Liu Wenfei , Fan Houbao , Zhou Guoyi , Giles‐Hansen Krysta , Liu Shirong , Wang Yi 
Published: January 2017

AbstractThe effects of forest cover change on water yield have long been studied across the globe. Several reviews have summarized the impacts of forest change and water yield from the small and paired watershed experiments, but no any synthetic assessment has been conducted on the basis of studies of large watersheds (>1,000 km2). We conducted a synthetic analysis on the basis of the studies from 162 large studied watersheds across the globe to explore how forest cover change affects annual water yield. Our first‐ever assessment confirms that deforestation increases annual water yield and reforestation decreases it, which is consistent with results from paired watershed experiments. More importantly, we found that forest cover and climate variability play a coequal role in annual water yield variations. The effects of forest cover change and climate variability on annual water yield variations can be additive or offsetting. Thus, their interactions can critically determine the magnitudes and directions of water yield changes. We also found that the hydrological sensitivities to forest cover change in smaller and dryer watersheds are higher than those in larger and wetter ones. The implications of these findings for sustainable water and watershed management are discussed in the context of future land cover and climate changes.
Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system
Authors: Gandy David A. , Rehage Jennifer S. 
Published: January 2017

AbstractNovel ecosystems result from a combination of altered historical abiotic regimes and new species assemblages. In freshwater systems, novel environmental conditions often result from large‐scale changes to hydrological connectivity as well as species invasions. Novel environmental conditions may affect the survival of aquatic fauna by altering dispersal patterns and resource fluctuations, and/or may impose physiological constraints on native species evolutionarily adapted to particular environments. Further, novel systems can provide insight into processes driving community structure because re‐sorting or filtering of regional biota is a likely consequence of decoupling from historical conditions. Although several studies document the presence of novel conditions, few examine variation or gradients in novelty. The Florida Everglades is a highly invaded and hydrologically altered system characterized by a large network of canals that compartmentalize the ecosystem and act to both increase and decrease connectivity. Little is known about how canals in this region function as habitat for native and nonnative fishes, the extent to which these canals may function as novel habitats, and how these habitat characteristics may influence distribution, abundance, and assembly patterns. In this study, we examined native and nonnative fish assemblages along a gradient of novelty, defined as the loss of wetland connectivity, influence of the natural hydrological regime, and habitat complexity (well connected to leveed canals). As novelty increased, native species richness and abundance strongly declined and the contribution of nonnatives increased to nearly 50%. Vast differences in community structure across the novelty gradient were strongly influenced by spatial factors and secondarily by hydrological factors, while habitat and abiotic factors were of very low relevance. Natives and nonnatives had opposing responses to key hydrological and habitat characteristics. Abundance of native fishes declined with decreased connectivity to adjacent marshes and canal littoral zone width, while nonnative fishes increased significantly in the most novel canals. Our results suggest that the inherent loss of natural environmental conditions and subsequent replacement by novel ones can lead to extensive changes in fish community structure. Success or failure at maintaining native assemblages will rely heavily on natural resource manager's ability to incorporate natural environmental characteristics with ecosystem restoration.
Temporal variability in large grazer space use in an experimental landscape
Authors: Raynor Edward J. , Joern Anthony , Skibbe Adam , Sowers Mark , Briggs John M. , Laws Angela N. , Goodin Douglas 
Published: January 2017

AbstractLand use, climate change, and their interaction each have great potential to affect grazing systems. With anticipated more frequent and extensive future drought, a more complete understanding of the mechanisms that determine large grazer landscape‐level distribution under varying climatic conditions is integral to ecosystem management. Using an experimental setting with contrasting fire treatments, we describe the inter‐annual variability of the effect of landscape topography and disturbance from prescribed spring fire on large grazer space use in years of variable resource availability. Using GPS telemetry, we investigated space use of plains bison (Bison bison bison) as they moved among watersheds managed with variable experimental burn treatments (1‐, 2‐, 4‐, and 20‐year burn intervals) during a seven‐year period spanning years of average‐to‐above average forage production and severe drought. At the landscape scale, bison more strongly favored high‐elevation and recently burned watersheds with watersheds burned for the first time in 2 or 4 yr consistently showing higher use relative to annually burned watersheds. In particular, watersheds burned for the first time in 4 yr were avoided to lesser extent than other more frequently burned watersheds during the dormant season. This management type also maintained coupling between bison space use and post‐fire regrowth across post‐drought growing season months, whereas watersheds with more frequent fire‐return intervals attracted bison in only the first month post‐fire. Hence, fire frequency played a role in maintaining the coupling of grazer and post‐fire regrowth, the fire–grazer interaction, in response to drought‐induced reduction in fuel loads. Moreover, bison avoided upland habitat in poor forage production years, when forage regrowth is less likely to occur in upland than in lowland habitats. Such quantified responses of bison to landscape features can aid future conservation management efforts and planning to sustain fire–grazer interactions and resulting spatial heterogeneity in grassland ecosystems.
Can niche plasticity promote biodiversity–productivity relationships through increased complementarity?
Authors: Niklaus Pascal A. , Baruffol Martin , He Jin‐Sheng , Ma Keping , Schmid Bernhard 
Published: January 2017

AbstractMost experimental biodiversity–ecosystem functioning research to date has addressed herbaceous plant communities. Comparably little is known about how forest communities will respond to species losses, despite their importance for global biogeochemical cycling. We studied tree species interactions in experimental subtropical tree communities with 33 distinct tree species mixtures and one, two, or four species. Plots were either exposed to natural light levels or shaded. Trees grew rapidly and were intensely competing above ground after 1.5 growing seasons when plots were thinned and the vertical distribution of leaves and wood determined by separating the biomass of harvested trees into 50 cm height increments. Our aim was to analyze effects of species richness in relation to the vertical allocation of leaf biomass and wood, with an emphasis on bipartite competitive interactions among species. Aboveground productivity increased with species richness. The community‐level vertical leaf and wood distribution depended on the species composition of communities. Mean height and breadth of species‐level vertical leaf and wood distributions did not change with species richness. However, the extra biomass produced by mixtures compared to monocultures of the component species increased when vertical leaf distributions of monocultures were more different. Decomposition of biodiversity effects with the additive partitioning scheme indicated positive complementarity effects that were higher in light than in shade. Selection effects did not deviate from zero, irrespective of light levels. Vertical leaf distributions shifted apart in mixed stands as consequence of competition‐driven phenotypic plasticity, promoting realized complementarity. Structural equation models showed that this effect was larger for species that differed more in growth strategies that were characterized by functional traits. In 13 of the 18 investigated two‐species mixtures, both species benefitted relative to intraspecific competition in monoculture. In the remaining five pairwise mixtures, the relative yield gain of one species exceeded the relative yield loss of the other species, resulting in a relative yield total (RYT) exceeding 1. Overall, our analysis indicates that richness–productivity relationships are promoted by interspecific niche complementarity at early stages of stand development, and that this effect is enhanced by architectural plasticity.
Potentiometric Determination of Ciprofloxacin in Physiological Fluids Using Carbon Paste and Nano‐Composite Carbon Paste Electrodes
Authors: Abdel‐Haleem Fatehy M. , Rizk Mahmoud S. , Badr Ibrahim H. A. 
Published: January 2017

AbstractNano‐composite carbon paste and simple carbon paste based potentiometric sensors were constructed and used for determination of ciprofloxacin at different pH values. Sensors were formulated utilizing graphite, suitable plasticizer, cirprofloxacinium‐phosphotungstate, as well as a highly lipophilic cation‐exchanger, sodium tetrakis(trifluoromethyl)phenyl borate. Effect of the incorporation of multi‐walled carbon nanotubes (MWCNTs) on the response characteristics of the prepared sensors was investigated. Results obtained were compared to that of a PVC‐sensor contains only the cation‐exchanger. In addition, the effect of solutions pH on the response characteristics was also studied; at pH 4.1, the slopes of bare carbon paste and MWCNTs‐based sensors were 55.7 and 66.6 mV/conc.decade in a concentration range of 10−2‐10−5 M with detection limits of 1.0x10−5 and 7.9x10−6 M, respectively. Although both sensors exhibited super‐Nernstian slopes at pH 2.0, the selectivity was improved compared to that measured at pH 4.1. Optimized sensors were successfully applied for the determination of ciprofloxacin in its pure form, pharmaceutical preparations, as well as spiked urine and serum samples, with high recovery.
Utility, reliability, sensitivity and validity of an online test system designed to monitor changes in cognitive function in clinical trials
Authors: Wesnes Keith A. , Brooker Helen , Ballard Clive , McCambridge Laura , Stenton Robert , Corbett Anne 
Published: January 2017

ObjectiveThe advent of long‐term remotely conducted clinical trials requires assessments which can be administered online. This paper considers the utility, reliability, sensitivity and validity of an internet‐based system for measuring changes in cognitive function which is being used in one such trial.MethodsThe Platform for Research Online to investigate Genetics and Cognition in Ageing is a 10‐year longitudinal and entirely remote study launched in November 2015. The CogTrackTM System is being used to monitor changes in important aspects of cognitive function using tests of attention, information processing and episodic memory. On study entry, the participants performed CogTrackTM up to three times over seven days, and these data are evaluated in this paper.ResultsDuring the first six months of the study, 14 531 individuals aged 50 to 94 years enrolled and performed the CogTrackTM System, 8627 of whom completed three test sessions. On the first administration, 99.4% of the study tasks were successfully completed. Repeated testing showed training/familiarisation effects on four of the ten measures which had largely stabilised by the third test session. The factor structure of the various measures was found to be robust. Evaluation of the influence of age identified clinically relevant declines over the age range of the population on one or more measures from all tasks.ConclusionsThe results of these analyses identify CogTrackTM to be a practical and valid method to reliably, sensitively, remotely and repeatedly collect cognitive data from large samples of individuals aged 50 and over. Copyright © 2017 John Wiley & Sons, Ltd.
The effects of low level laser therapy on both HIV‐1 infected and uninfected TZM‐bl cells
Authors: Lugongolo Masixole Yvonne , Manoto Sello Lebohang , Ombinda‐Lemboumba Saturnin , Maaza Malik , Mthunzi‐Kufa Patience 
Published: January 2017

Human immunodeficiency virus (HIV‐1) infection remains a major health problem despite the use of highly active antiretroviral therapy (HAART), which has greatly reduced mortality rates. Due to the unavailability of an effective vaccine and treatment that would completely eradicate the virus in infected individuals, the quest for new therapies continues. Low level laser therapy (LLLT) involves the exposure of cells to low levels of red or infrared light. LLLT has been widely used in different medical conditions, but not in HIV‐1 infection. This study aimed to determine the effects of LLLT on HIV‐1 infected and uninfected TZM‐bl cells. Both infected and uninfected cells were irradiated at a wavelength of 660 nm with different fluences from 2 J/cm2 to 10 J/cm2. Changes in cellular responses were assessed using cell morphology, viability, proliferation, cytotoxicity and luciferase activity assays. Upon data analysis, uninfected irradiated cells showed no changes in cell morphology, viability, proliferation and cytotoxicity, while the infected irradiated cells did. In addition, laser irradiation reduced luciferase activity in infected cells. Finally, laser irradiation had no inhibitory effect in uninfected cells, whereas it induced cell damage in a dose dependent manner in infected cells.
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Impact of dianionic and dicationic linkers on tumor uptake and biodistribution of [64Cu]Cu/NOTA peptide‐based gastrin‐releasing peptide receptors antagonists
Authors: Mansour Nematallah , Dumulon‐Perreault Véronique , Ait‐Mohand Samia , Paquette Michel , Lecomte Roger , Guérin Brigitte 
Published: January 2017

In this study, we investigated for the first time the influence of 2‐aminoethyl‐piperazine‐1‐carboxylic acid (APCA) and amino‐hexanedioic‐1‐acid (AHDA) on tumor uptake and elimination kinetics of [64Cu]‐radiolabeled gastrin releasing peptide receptors (GRPR) antagonists. Three GRPR antagonists containing the RM26 sequence were synthesized and conjugated with NOTA via different linkers (LK): polyethylene glycol (PEG–neutral), APCA (dicationic) or AHDA (dianionic). The NOTA‐LK‐RM26 peptides were radiolabeled with 64Cu to assess their pharmacokinetic and positron emission tomography (PET) imaging properties using PC3 tumor‐bearing athymic nude mice. The inhibition constants (Ki) of the 3 natCu/NOTA‐LK‐RM26 peptides bearing PEG, dicationic and dianionic linkers were 0.98 ± 0.48 nM, 0.95 ± 0.21 nM, and 17.97 ± 2.79 nM, respectively. The [64Cu] NOTA‐LK‐RM26 conjugates were prepared with labeling yields superior to 95% and specific activities of 67 to 77 TBq/mmol. The 3 radiopeptides were stable in vivo and showed GRPR‐specific uptake in pancreas with a very fast washout of this tissue observed for [64Cu]‐NOTA‐AHDA‐RM26 peptide. Results from imaging studies displayed specific PC3 tumor uptake for both [64Cu]‐NOTA‐APCA‐ and AHDA‐RM26, similar kidney elimination and fast liver washout. Considering their adequate imaging characteristics, [64Cu]‐NOTA‐LK‐RM26 bearing APCA‐ and AHDA‐linkers are promising candidates for GRPR‐targeted PET imaging prostate cancer.