bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Catalytic Oxidation of Cyclohexene with Molecular Oxygen: Radical Versus Nonradical Pathways
Authors: Denekamp Ilse M. , Antens Martijn , Slot Thierry K. , Rothenberg Gadi 
Published: October 2017

AbstractWe study the allylic oxidation of cyclohexene with O2 under mild conditions in the presence of transition‐metal catalysts. The catalysts comprise nanometric metal oxide particles supported on porous N‐doped carbons (M/N:C, M=V, Cr, Fe, Co, Ni, Cu, Nb, Mo, W). Most of these metal oxides give only moderate conversions, and the majority of the products are over‐oxidation products. Co/N:C and Cu/N:C, however, give 70–80 % conversion and 40–50 % selectivity to the ketone product, cyclohexene‐2‐one. Control experiments in which we used free‐radical scavengers show that the oxidation follows the expected free‐radical pathway in almost all cases. Surprisingly, the catalytic cycle in the presence of Cu/N:C does not involve free‐radical species in solution. Optimisation of this catalyst gives >85 % conversion with >60 % selectivity to the allylic ketone at 70 °C and 10 bar O2. We used SEM, X‐ray photoelectron spectroscopy and XRD to show that the active particles have a cupric oxide/cuprous oxide core–shell structure, giving a high turnover frequency of approximately 1500 h−1. We attribute the high performance of this Cu/N:C catalyst to a facile surface reaction between adsorbed cyclohexenyl hydroperoxide molecules and activated oxygen species.
Performance of Nanofiltration‐Like Forward‐Osmosis Membranes for Aerobically Treated Palm Oil Mill Effluent
Authors: Abdullah Wan Nur Ain Shuhada , Lau Woei-Jye , Aziz Farhana , Emadzadeh Daryoush , Ismail Ahmad Fauzi 
Published: October 2017

AbstractFor the first time, engineered osmosis was performed using commercial nanofiltration (NF) membranes for the treatment process of aerobically treated palm oil mill effluent (AT‐POME). Compared to conventional forward‐osmosis (FO) membranes with dense rejection layer, the NF‐like FO membranes offer a higher water flux with minimum reverse solute flux provided appropriate solutes like divalent salts or polyelectrolytes were used in the draw solution. Both NF membranes were able to treat the AT‐POME by completely preventing the color component from passing through the permeate side under FO and pressure‐retarded osmosis (PRO) orientation. The water fluxes of the membranes were higher under PRO orientation owing to the reduced internal concentration polarization effect. Relatively loose membranes for the engineered osmosis application could address severe surface fouling of membranes tested under pressure‐driven filtration.
Chiral Discrimination through 1H NMR and Luminescence Spectroscopy: Dynamic Processes and Solid Strip for Chiral Recognition
Authors: Gangopadhyay Monalisa , Maity Arunava , Dey Ananta , Rajamohanan P. R. , Ravindranathan Sapna , Das Amitava 
Published: October 2017

AbstractThe appropriate choice of the host molecules with well‐defined optical activity (S‐H/R‐H) helps in the differentiation between two secondary ammonium ion‐derivative guest molecules with different optical activities (R‐G/S‐G) based on the fluorescence resonance energy transfer (FRET)‐based luminescence responses. Crown ether‐based host molecules with opposite chiral configurations (R‐H, S‐H) have been derived from 1,1′‐bi‐2‐naphthol (BINOL) derivatives that have axially chiral biaryl centers. These chiral crown ethers form host–guest complexes (i.e., [2]pseudorotaxanes) with chiral secondary ammonium ion derivatives (R‐G, S‐G). NMR spectroscopic studies show that the complexes are in a dynamic equilibrium in solution. Results of the 1H NMR and fluorescence spectroscopic studies indicate a head‐on orientation of the host and guest in the [2]pseudorotaxanes. The difference in the efficiency in the FRET‐based responses between anthracene and the BINOL derivatives allow efficient chiral discrimination of the guests. Isothermal titration calorimetry and NMR investigations reveal that inclusion complexes between hosts and guests of the same chirality (R‐H⋅R‐G, S‐H⋅S‐G) are more stable relative to those of opposite chirality (R‐H⋅S‐G, S‐H⋅R‐G). However, FRET‐based energy‐transfer efficiency is higher for R‐H⋅S‐G and S‐H⋅R‐G complexes. NMR spectroscopic studies show that the relative orientation of the guest in the host cavity is significantly different when the host binds a guest of the same or opposite chirality; furthermore, the latter is more favorable for FRET, thus enabling discrimination between enantiomers. Interestingly, chiral discrimination of guest ions could also be achieved by using silica surfaces modified with chiral host molecules.
Surface‐Enhanced Raman Spectroscopy Characterization of Salt‐Induced Aggregation of Gold Nanoparticles
Authors: Chan Matthew Y. , Leng Weinan , Vikesland Peter J. 
Published: October 2017

AbstractLow‐frequency (<300 cm−1) vibrational interactions between gold surfaces and dissolved halides in water were investigated by surface‐enhanced Raman spectroscopy (SERS). Experiments with NaF, NaCl, NaBr, and NaI salts indicate that the Raman shifts of the Au‐X− SERS bands correlate with the bond strength of the corresponding covalent interaction. These low‐frequency SERS bands open up new means to investigate the aggregation of nanoparticles in aqueous environments.
Role of the Chalcogen (S, Se, Te) in the Oxidation Mechanism of the Glutathione Peroxidase Active Site
Authors: Bortoli Marco , Torsello Mauro , Bickelhaupt F. Matthias , Orian Laura 
Published: October 2017

AbstractThe front cover artwork is provided by the groups of Prof. Dr. F. Matthias Bickelhaupt (VU Amsterdam, The Netherlands) and Prof. Dr. Laura Orian (Università degli Studi di Padova, Italy). The GPx active sites resemble lightning bolts during a thunderstorm (S and Te mutants), and during a clear night for Sec‐GPx, associating its much higher anti‐oxidant power to the tremendously powerful positive lightning bolts. Read the full text of the article at 10.1002/cphc.201700743.
Improved Free‐Energy Landscape Quantification Illustrated with a Computationally Designed Protein–Ligand Interaction
Authors: Van Patten William J. , Walder Robert , Adhikari Ayush , Okoniewski Stephen R. , Ravichandran Rashmi , Tinberg Christine E. , Baker David , Perkins Thomas T. 
Published: October 2017

AbstractQuantifying the energy landscape underlying protein–ligand interactions leads to an enhanced understanding of molecular recognition. A powerful yet accessible single‐molecule technique is atomic force microscopy (AFM)‐based force spectroscopy, which generally yields the zero‐force dissociation rate constant (koff) and the distance to the transition state (Δx≠). Here, we introduce an enhanced AFM assay and apply it to probe the computationally designed protein DIG10.3 binding to its target ligand, digoxigenin. Enhanced data quality enabled an analysis that yielded the height of the transition state (ΔG≠=6.3±0.2 kcal mol−1) and the shape of the energy barrier at the transition state (linear‐cubic) in addition to the traditional parameters [koff (=4±0.1×10−4 s−1) and Δx≠ (=8.3±0.1 Å)]. We expect this automated and relatively rapid assay to provide a more complete energy landscape description of protein–ligand interactions and, more broadly, the diverse systems studied by AFM‐based force spectroscopy.
How beta diversity and the underlying causes vary with sampling scales in the Changbai mountain forests
Authors: Tan Lingzhao , Fan Chunyu , Zhang Chunyu , von Gadow Klaus , Fan Xiuhua 
Published: October 2017

AbstractThis study aims to establish a relationship between the sampling scale and tree species beta diversity temperate forests and to identify the underlying causes of beta diversity at different sampling scales. The data were obtained from three large observational study areas in the Changbai mountain region in northeastern China. All trees with a dbh ≥1 cm were stem‐mapped and measured. The beta diversity was calculated for four different grain sizes, and the associated variances were partitioned into components explained by environmental and spatial variables to determine the contributions of environmental filtering and dispersal limitation to beta diversity. The results showed that both beta diversity and the causes of beta diversity were dependent on the sampling scale. Beta diversity decreased with increasing scales. The best‐explained beta diversity variation was up to about 60% which was discovered in the secondary conifer and broad‐leaved mixed forest (CBF) study area at the 40 × 40 m scale. The variation partitioning result indicated that environmental filtering showed greater effects at bigger grain sizes, while dispersal limitation was found to be more important at smaller grain sizes. What is more, the result showed an increasing explanatory ability of environmental effects with increasing sampling grains but no clearly trend of spatial effects. The study emphasized that the underlying causes of beta diversity variation may be quite different within the same region depending on varying sampling scales. Therefore, scale effects should be taken into account in future studies on beta diversity, which is critical in identifying different relative importance of spatial and environmental drivers on species composition variation.
Receptor uptake arrays for vitamin B12, siderophores, and glycans shape bacterial communities
Authors: Frank Steven A. 
Published: October 2017

AbstractMolecular variants of vitamin B12, siderophores, and glycans occur. To take up variant forms, bacteria may express an array of receptors. The gut microbeBacteroides thetaiotaomicronhas three different receptors to take up variants of vitamin B12and 88 receptors to take up various glycans. The design of receptor arrays reflects key processes that shape cellular evolution. Competition may focus each species on a subset of the available nutrient diversity. Some gut bacteria can take up only a narrow range of carbohydrates, whereas species such asB. thetaiotaomicroncan digest many different complex glycans. Comparison of different nutrients, habitats, and genomes provides opportunity to test hypotheses about the breadth of receptor arrays. Another important process concerns fluctuations in nutrient availability. Such fluctuations enhance the value of cellular sensors, which gain information about environmental availability and adjust receptor deployment. Bacteria often adjust receptor expression in response to fluctuations of particular carbohydrate food sources. Some species may adjust expression of uptake receptors for specific siderophores. How do cells use sensor information to control the response to fluctuations? This question about regulatory wiring relates to problems that arise in control theory and artificial intelligence. Control theory clarifies how to analyze environmental fluctuations in relation to the design of sensors and response systems. Recent advances in deep learning studies of artificial intelligence focus on the architecture of regulatory wiring and the ways in which complex control networks represent and classify environmental states. I emphasize the similar design problems that arise in cellular evolution, control theory, and artificial intelligence. I connect those broad conceptual aspects to many testable hypotheses for bacterial uptake of vitamin B12, siderophores, and glycans.
Energy and speleogenesis: Key determinants of terrestrial species richness in caves
Authors: Jiménez‐Valverde Alberto , Sendra Alberto , Garay Policarp , Reboleira Ana Sofia P. S. 
Published: October 2017

AbstractThe aim of this study was to unravel the relative role played by speleogenesis (i.e., the process in which a cave is formed), landscape‐scale variables, and geophysical factors in the determination of species richness in caves. Biological inventories from 21 caves located in the southeastern Iberian Peninsula along with partial least square (PLS) regression analysis were used to assess the relative importance of the different explanatory variables. The caves were grouped according to the similarity in their species composition; the effect that spatial distance could have on similarity was also studied using correlation between matrices. The energy and speleogenesis of caves accounted for 44.3% of the variation in species richness. The trophic level of each cave was the most significant factor in PLS regression analysis, and epigenic caves (i.e., those formed by the action of percolating water) had significantly more species than hypogenic ones (i.e., those formed by the action of upward flows in confined aquifers). Dissimilarity among the caves was very high (multiple‐site βsim = 0.92). Two main groups of caves were revealed through the cluster analysis, one formed by the western caves and the other by the eastern ones. The significant—but low—correlation found between faunistic dissimilarity and geographical distance (r = .16) disappeared once the caves were split into the two groups. The extreme beta‐diversity suggests a very low connection among the caves and/or a very low dispersal capacity of the species. In the region under study, two main factors are intimately related to the richness of terrestrial subterranean species in caves: the amount of organic material (trophic level) and the formation process (genesis). This is the first time that the history of a cave genesis has been quantitatively considered to assess its importance in explaining richness patterns in comparison with other factors more widely recognized.
The Impact of Self‐Reported Impulsivity on the Course of Weight Is Mediated by Disinhibited Eating
Authors: Legenbauer Tanja , Müller Astrid , de Zwaan Martina , Fischer Charlotte , Burgmer Ramona , Herpertz Stephan 
Published: October 2017

AbstractThis study investigates the impact of impulsivity and the mediating role of disinhibited eating behaviour (DEB) on weight and weight trajectories in a large data set including obese non‐treatment seeking individuals (obese control, n = 138) and obese individuals who were either receiving a conventional treatment program (n = 227) or bariatric surgery (n = 123). Data was assessed one, 4 and 9 years after baseline including self‐reports for impulsivity and DEB. Results suggest a significant association between impulsivity and body mass index, which is partially mediated by DEB. Longitudinally, the influence of impulsivity on the course of weight after 9 years was fully mediated by DEB in obese control but not in the treatment groups. The results indicate an interplay between impulsivity and DEB with respect to obesity. Further research is needed to clarify how the mediation works and when it exerts its effect, in order to identify those that might profit from a specific (impulsivity‐reducing) training. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.
Anaerobic biotransformation of N-methyl perfluorobutanesulfonamido ethanol and N-ethyl perfluorooctanesulfonamido ethanol
Authors: Lange Cleston C. 
Published: October 2017

Abstract

Some fluorochemical products are manufactured using N-methyl perfluorobutanesulfonamido ethanol (MeFBSE), a short-chain replacement for perfluorooctyl-based chemistries N-methyl and N-ethyl perfluorooctanesulfonamido ethanols (EtFOSE). The present study shows for the first time the anaerobic biodegradation of MeFBSE and EtFOSE in municipal digester sludge under methanogenic conditions. Both MeFBSE and EtFOSE were incubated for 108 d with anaerobic digester sludge. Although sterile controls did not remove MeFBSE, it was degraded in live sludge. The loss of MeFBSE coincided with production of N-methyl perfluorobutanesulfonamido acetate (MeFBSAA) and perfluorobutane sulfinate (PFBSI). The biodegradation appeared biphasic, with pseudo first-order loss between days 0 and 70, resulting in approximately 75% removal but no further depletion of MeFBSE between days 70 and 108. By day 108 MeFBSAA and PFBSI accounted for 57 and 40 mol% of initial dose, respectively. Mass balance values in live cultures on days 0, 10, 21, 29, 70, and 108 were 103, 92, 94, 100, 93, and 122%, respectively. The apparent first-order biodegradation rate constant for MeFBSE over the first 70 d was 0.0194 d−1, and the apparent half-life was 35.8 d. Incubation of EtFOSE with live digester sludge resulted in low-level formation of N-ethyl perfluorooctane-sulfonamido acetate and perfluorooctane sulfinate, which did not form in sterile controls. Although it was not measurably lost, 2 to 3% loss of EtFOSE was calculated based on product concentrations. The total product formation rate constant was determined by first-order kinetic evaluation over the first 72 d to estimate a first-order biodegradation rate constant for EtFOSE at 0.000374 d−1, and the apparent half-life time was 1860 d. Environ Toxicol Chem 2018;37:768–779. © 2017 SETAC
Factors affecting the dissipation of pharmaceuticals in freshwater sediments
Authors: Al-Khazrajy Omar S.A. , Bergström Ed , Boxall Alistair B.A. 
Published: October 2017

Abstract

Degradation is one of the key processes governing the impact of pharmaceuticals in the aquatic environment. Most studies on the degradation of pharmaceuticals have focused on soil and sludge, with fewer exploring persistence in aquatic sediments. We investigated the dissipation of 6 pharmaceuticals from different therapeutic classes in a range of sediment types. Dissipation of each pharmaceutical was found to follow first-order exponential decay. Half-lives in the sediments ranged from 9.5 (atenolol) to 78.8 (amitriptyline) d. Under sterile conditions, the persistence of pharmaceuticals was considerably longer. Stepwise multiple linear regression analysis was performed to explore the relationships between half-lives of the pharmaceuticals, sediment physicochemical properties, and sorption coefficients for the compounds. Sediment clay, silt, and organic carbon content and microbial activity were the predominant factors related to the degradation rates of diltiazem, cimetidine, and ranitidine. Regression analysis failed to highlight a key property which may be responsible for observed differences in the degradation of the other pharmaceuticals. The present results suggest that the degradation rate of pharmaceuticals in sediments is determined by different factors and processes and does not exclusively depend on a single sediment parameter. Environ Toxicol Chem 2018;37:829–838. © 2017 SETAC
Anisotropic adaptive stabilized finite element solver for RANS models
Authors: Sari J. , Cremonesi F. , Khalloufi M. , Cauneau F. , Meliga P. , Mesri Y. , Hachem E. 
Published: October 2017

SummaryAerodynamic characteristics of various geometries are predicted using a finite element formulation coupled with several numerical techniques to ensure stability and accuracy of the method. First, an edge‐based error estimator and anisotropic mesh adaptation are used to detect automatically all flow features under the constraint of a fixed number of elements, thus controlling the computational cost. A variational multiscale‐stabilized finite element method is used to solve the incompressible Navier‐Stokes equations. Finally, the Spalart‐Allmaras turbulence model is solved using the streamline upwind Petrov‐Galerkin method. This paper is meant to show that the combination of anisotropic unsteady mesh adaptation with stabilized finite element methods provides an adequate framework for solving turbulent flows at high Reynolds numbers. The proposed method was validated on several test cases by confrontation with literature of both numerical and experimental results, in terms of accuracy on the prediction of the drag and lift coefficients as well as their evolution in time for unsteady cases.
Toxicological parameters of albino rats fed with extruded snacks from Aerial yam (Dioscoria bulbifera) and African breadfruit seed (Treculia africana)
Authors: Olatoye Kazeem K. , Arueya Gibson L. 
Published: October 2017

AbstractIn this study, safety of novel food from aerial yam and Treculia africana, underutilized food materials with high‐nutritive value and health benefits were investigated. Animal experiment involving the use of thirty (30) male albino rats was conducted for 28 days.Thereafter, rats in all groups were sacrificed and blood samples collected for biochemical analysis and hematological assay. Some vital organs were harvested and used for histological analysis. Biochemical and hematological parameters were not significantly p ≤ .05 different among the treatment and controls. However there was an increase in monocytes, which is a reflection of immune boosting potential of the novel snack. No significant pathological changes were observed in liver and kidney of rats fed with this snack. Rats showed no signs of toxicity within the study period. These findings suggest that product may be safe and useful as an Immune adjuvant.
Mechanisms of lysophosphatidylcholine‐induced demyelination: A primary lipid disrupting myelinopathy
Authors: Plemel Jason R. , Michaels Nathan J. , Weishaupt Nina , Caprariello Andrew V. , Keough Michael B. , Rogers James A. , Yukseloglu Aran , Lim Jaehyun , Patel Vikas V. , Rawji Khalil S. , Jensen Samuel K. , Teo Wulin , Heyne Belinda , Whitehead Shawn N. , Stys Peter K. , Yong V. Wee 
Published: October 2017

AbstractFor decades lysophosphatidylcholine (LPC, lysolecithin) has been used to induce demyelination, without a clear understanding of its mechanisms. LPC is an endogenous lysophospholipid so it may cause demyelination in certain diseases. We investigated whether known receptor systems, inflammation or nonspecific lipid disruption mediates LPC‐demyelination in mice. We found that LPC nonspecifically disrupted myelin lipids. LPC integrated into cellular membranes and rapidly induced cell membrane permeability; in mice, LPC injury was phenocopied by other lipid disrupting agents. Interestingly, following its injection into white matter, LPC was cleared within 24 hr but by five days there was an elevation of endogenous LPC that was not associated with damage. This elevation of LPC in the absence of injury raises the possibility that the brain has mechanisms to buffer LPC. In support, LPC injury in culture was significantly ameliorated by albumin buffering. These results shed light on the mechanisms of LPC injury and homeostasis.
Surface modification of bulk titanium substrates for biomedical applications via low‐temperature microwave hydrothermal oxidation
Authors: Cheng Alice , Goodwin W. Brandon , deGlee Ben M. , Gittens Rolando A. , Vernon Jonathan P. , Hyzy Sharon L. , Schwartz Zvi , Sandhage Kenneth H. , Boyan Barbara D. 
Published: October 2017

AbstractMicro‐to‐nanoscale surface topographies of orthopaedic and dental implants can affect fluid wetting and biological response. Nanoscale features can be superimposed on microscale roughness of titanium (Ti) surfaces at high temperatures, resulting in increased osteoblast differentiation. However, high temperatures can compromise mechanical properties of the bulk material. Here, we have developed a novel low‐temperature microwave hydrothermal (MWHT) oxidation process for nanomodification of microrough (SLA) Ti surfaces. Nanoscale protuberances (20 –100 nm average diameter) were generated on SLA surfaces via MWHT treatment at 200°C in H2O, or in aqueous solutions of H2O2 or NH4OH, for times ranging from 1 to 40 h. The size, shape, and crystalline content of the nanoprotuberances varied with the solution used and treatment time. The hydrophilicity of all MWHT‐modified surfaces was dramatically enhanced. MG63 and normal human osteoblasts (NHOsts) were cultured on MWHT‐treated SLA surfaces. While most responses to MWHT‐modified surfaces were comparable to those seen on SLA controls, the MWHT‐generated nanotopography reduced osteocalcin production by NHOst cells, suggesting that specific nanotopographic characteristics differentially mediate osteoblast phenotypic expression. MWHT processing provides a scalable, low‐temperature route for tailoring nanoscale topographies on microroughened titanium implant surfaces with significantly enhanced wetting by water, without degrading the microscale surface structure of such implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 782–796, 2018.