bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of an Improved Rhodium Catalyst for Z‐Selective Anti‐Markovnikov Addition of Carboxylic Acids to Terminal Alkynes
Authors: Wei Siping , Pedroni Julia , Meißner Antje , Lumbroso Alexandre , Drexler Hans‐Joachim , Heller Detlef , Breit Bernhard 
Published: July 2013

AbstractTo develop more active catalysts for the rhodium‐catalyzed addition of carboxylic acids to terminal alkynes furnishing anti‐Markovnikov Z enol esters, a thorough study of the rhodium complexes involved was performed. A number of rhodium complexes were characterized by NMR, ESI‐MS, and X‐ray analysis and applied as catalysts for the title reaction. The systematic investigations revealed that the presence of chloride ions decreased the catalyst activity. Conversely, generating and applying a mixture of two rhodium species, namely, [Rh(DPPMP)2][H(benzoate)2] (DPPMP=diphenylphosphinomethylpyridine) and [{Rh(COD)(μ2‐benzoate)}2], provided a significantly more active catalyst. Furthermore, the addition of a catalytic amount of base (Cs2CO3) had an additional accelerating effect. This higher catalyst activity allowed the reaction time to be reduced from 16 to 1–4 h while maintaining high selectivity. Studies on the substrate scope revealed that the new catalysts have greater functional‐group compatibility.
A Study of 5‐(1,2,4‐Triazol‐C‐yl)tetrazol‐1‐ols: Combining the Benefits of Different Heterocycles for the Design of Energetic Materials
Authors: Dippold Alexander A. , Izsák Dániel , Klapötke Thomas M. 
Published: July 2013

AbstractThe synthesis and full structural and spectroscopic characterization of three 5‐(1,2,4‐triazol‐C‐yl)tetrazol‐1‐ol compounds with selected energetic moieties including nitrimino (5), nitro (6) and azido (7) groups are reported. The influence of those energetic moieties as well as the CC connection of a tetrazol‐1‐ol and a 1,2,4‐triazole on structural and energetic properties has been investigated. All compounds were well characterized by various means, including IR and multinuclear NMR spectroscopy, mass spectrometry, and DSC. The molecular structures of 5–8 were determined in the solid state by single‐crystal X‐ray diffraction. The standard heats of formation were calculated on the CBS‐4M level of theory utilizing the atomization energy method, revealing highly positive values for all compounds. The detonation parameters were calculated with the EXPLO5 program and compared to the common secondary explosive RDX. Additionally, sensitivities towards impact, friction and electrostatic discharge were determined.
Copper‐Catalyzed Oxidative Amination and Allylic Amination of Alkenes
Authors: Liwosz Timothy W. , Chemler Sherry R. 
Published: July 2013

AbstractEnamines and enamides are useful synthetic intermediates and common components of bioactive compounds. A new protocol for their direct synthesis by a net alkene CH amination and allylic amination by using catalytic CuII in the presence of MnO2 is reported. Reactions between N‐aryl sulfonamides and vinyl arenes furnish enamides, allylic amines, indoles, benzothiazine dioxides, and dibenzazepines directly and efficiently. Control experiments further showed that MnO2 alone can promote the reaction in the absence of a copper salt, albeit with lower efficiency. Mechanistic probes support the involvement of nitrogen‐radical intermediates. This method is ideal for the synthesis of enamides from 1,1‐disubstituted vinyl arenes, which are uncommon substrates in existing oxidative amination protocols.
Stereoselective Toxicity and Metabolism of Lactofen in Primary Hepatocytes From Rat
Authors: Wang Xinru , Diao Jinling , Shen Zhigang , Zhu Wentao , Zhang Ping , Zhou Zhiqiang 
Published: July 2013

ABSTRACTThe stereoselective metabolism of lactofen in primary rat hepatocytes was studied using a chiral high‐performance liquid chromatographic (HPLC) method. Rac‐lactofen and its two enantiomers, S‐(+)‐ and R‐(−)‐lactofen, as well as two of its major metabolites, acifluorfen, S‐(+)‐ and R‐(−)‐desethyl lactofen, were used as substrates,. The single and joint cytotoxicity of parent compounds and the metabolites were assessed by coincubation with rat hepatocytes as target cells. Cytotoxicity was determined by the methyl tetrazolium (MTT) assay. In hepatocyte incubations, S‐(+)‐lactofen was degraded more rapidly than R‐(−)‐lactofen, and a stereospecific formation of S‐(+)‐desethyl lactofen was detected. Metabolism of lactofen to desethyl lactofen was processed with the retention of configuration, and the achiral compound, acifluorfen, was the shared metabolite generated from both S‐(+)‐ and R‐(−)‐lactofen. There was no chiral conversion of lactofen or desethyl lactofen enantiomers during the incubation. For the cytotoxicity research, the calculated EC50 values indicated that when being applied individually, the parent compound was less toxic than its metabolites, while the combination with metabolites enhanced its cytotoxic effects. The data presented here would be helpful for a more comprehensive assessment of the ecotoxicological and environmental risks of lactofen. Chirality 25:743–750, 2013. © 2013 Wiley Periodicals, Inc.
Ultrafast NMR T1 Relaxation Measurements: Probing Molecular Properties in Real Time
Authors: Smith Pieter E. S. , Donovan Kevin J. , Szekely Or , Baias Maria , Frydman Lucio 
Published: July 2013

AbstractThe longitudinal relaxation properties of NMR active nuclei carry useful information about the site‐specific chemical environments and about the mobility of molecular fragments. Molecular mobility is in turn a key parameter reporting both on stable properties, such as size, as well as on dynamic ones, such as transient interactions and irreversible aggregation. In order to fully investigate the latter, a fast sampling of the relaxation parameters of transiently formed molecular species may be needed. Nevertheless, the acquisition of longitudinal relaxation data is typically slow, being limited by the requirement that the time for which the nucleus relaxes be varied incrementally until a complete build‐up curve is generated. Recently, a number of single‐shot‐inversion‐recovery methods have been developed capable of alleviating this need; still, these may be challenged by either spectral resolution restrictions or when coping with very fast relaxing nuclei. Here, we present a new experiment to measure the T1s of multiple nuclear spins that experience fast longitudinal relaxation, while retaining full high‐resolution chemical shift information. Good agreement is observed between T1s measured with conventional means and T1s measured using the new technique. The method is applied to the real‐time investigation of the reaction between D‐xylose and sodium borate, which is in turn elucidated with the aid of ancillary ultrafast and conventional 2D TOCSY measurements.
Redox‐Mediated Synthesis of Functionalised Graphene: A Strategy towards 2D Multifunctional Electrocatalysts for Energy Conversion Applications
Authors: Unni Sreekuttan M. , Bhange Siddheshwar N. , Anothumakkool Bihag , Kurungot Sreekumar 
Published: July 2013

AbstractA simple, one‐step synthetic route for developing a two‐dimensional multifunctional electrocatalyst is reported, by the functionalisation of graphene using oxidised ethylenedioxythiophene (O‐EDOT). The mutually assisted redox reaction between graphene oxide (GO) and EDOT facilitates the reduction of GO to graphene with a concomitant deposition of O‐EDOT on the surface of the graphene. The oxidised surface of GO catalyses the reaction without using an added reducing agent, so a controlled and uniform deposition of O‐EDOT is ensured on the surface of graphene, which essentially prevents the restacking of the layers. UV/Visible, IR, Raman and X‐ray photoelectron spectroscopy give valid evidence for the reduction and functionalisation of graphene sheets. The functional groups present on the surface of graphene are found to tune the physical and chemical properties of graphene. Consequently, the functionalised material displays enhanced electrocatalytic activity for the reduction of oxygen to water and I3− to I− relative to pristine graphene. These distinct property characteristics make the material a versatile cathode electrocatalyst for both alkaline anion‐exchange membrane fuel cells and dye‐sensitised solar cells.
The Pharmacobiotic Potential of the Gastrointestinal Tract Micro‐Biometabolome–Probiotic Connect: A Brief Commentary
Authors: Vitetta Luis , Alford Hollie 
Published: July 2013

AbstractGiven that the gastrointestinal tract (GIT) mucosa is one of the most metabolically active tissues, basic research spanning over the last three decades has also recognized that the idea that microbes are to be eliminated at all costs is flawed. This research has significantly redefined the exchanges between gut‐dwelling microbes and vertebrates by recognizing that the microbial active cohort and its mammalian host have shared critical coevolutionary metabolic interactions that span millennia. As such, the GIT microbiome may also be the site for the production of novel molecules that exhibit therapeutic efficacy, realizing a long held notion that the GIT commensal cohort is a site for pharmacobiotic activity. Indeed basic and clinical research aimed at manipulating the GIT microbiota demonstrates the potential that exists in the microbiological production of nutra‐pharmaceuticals. In this commentary/brief review we develop a hypothesis that multi‐strain probiotics can influence the commensal microbiota in the GIT in a beneficial manner by upregulating the pharmacobiotic potential of the microbial cohort. Furthermore, we illustrate this with a biologically plausible posit for the beneficial use of a multi‐strain probiotic to prevent and treat Clostridium difficile–associated diarrhea. As such we further posit in this review that microbial cohorts (e.g., in the GIT) present bacterial communities with an overwhelming accuracy at identifying pathogens/pathogenic states than do current diagnostic methodologies; this then plausibly leading to future microbe directed site‐specific therapeutics.
Do elevations in temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated silver birch seedlings?
Authors: Huttunen Liisa , Saravesi Karita , Markkola Annamari , Niemelä Pekka 
Published: July 2013

AbstractClimate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1‐year‐old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.
Flexible mate choice when mates are rare and time is short
Authors: Tinghitella Robin M. , Weigel Emily G. , Head Megan , Boughman Janette W. 
Published: July 2013

AbstractFemale mate choice is much more dynamic than we once thought. Mating decisions depend on both intrinsic and extrinsic factors, and these two may interact with one another. In this study, we investigate how responses to the social mating environment (extrinsic) change as individuals age (intrinsic). We first conducted a field survey to examine the extent of natural variation in mate availability in a population of threespine sticklebacks. We then manipulated the sex ratio in the laboratory to determine the impact of variation in mate availability on sexual signaling, competition, and mating decisions that are made throughout life. Field surveys revealed within season heterogeneity in mate availability across breeding sites, providing evidence for the variation necessary for the evolution of plastic preferences. In our laboratory study, males from both female‐biased and male‐biased treatments invested most in sexual signaling late in life, although they competed most early in life. Females became more responsive to courtship over time, and those experiencing female‐biased, but not male‐biased sex ratios, relaxed their mating decisions late in life. Our results suggest that social experience and age interact to affect sexual signaling and female mating decisions. Flexible behavior could mediate the potentially negative effects of environmental change on population viability, allowing reproductive success even when preferred mates are rare.
Community patterns of the small riverine benthos within and between two contrasting glacier catchments
Authors: Eisendle‐Flöckner Ursula , Jersabek Christian D. , Kirchmair Martin , Hashold Kerstin , Traunspurger Walter 
Published: July 2013

AbstractOngoing glacial retreat is expected to lead to numerous changes in glacier‐fed rivers. This study documents the development of community composition of the hitherto widely neglected micro‐ and meiobenthos (MMB: bacteria, fungi, algae, protists, and meiofauna) in glacier rivers in response to the distinct habitat conditions driven by different stages of (de)glacierization. Our model is based on the glacier catchments of the Möll River (MC) and Kleinelendbach stream (KC), in the Austrian Alps, with 60% and 25% glacierization and glacier retreats of 403 and 26 m, respectively, since 1998. Analyses of overall catchment diversity and resemblance patterns showed that neither intense glacierization nor rapid deglacierization were predominant MMB determinants. This was ascribed to the specific environmental conditions at the MC, where the rapidly retreating Pasterze glacier has formed a harsh unstable proglacial, but also a benign floodplain area, with the former suppressing and the latter supporting the structural development of the MMB. Comparisons of similarly aged riverine habitats of the MC proglacial and the KC main channel further evidenced developmental suppression of the MMB (64 taxa) by the rapidly retreating MC glacier, unlike the moderate glacial retreat in the KC (130 taxa). Habitat conditions interacting with melt periods explained the differences in MMB resemblance patterns, which themselves differentially reflected the spatiotemporal habitat settings imposed by the different glacier activities. The varying glacial influences were represented by a glaciality index (GIm) based on water temperature, electrical conductivity, and stream bed stability. The taxonomic richness of nematodes, rotifers, algae, and diatoms was distinctly related to this index, as were most MMB abundances. However, the strongest relationships to the GIm were those of nematode abundances and maturity. Our observations highlight the intense response of the MMB to ongoing glacier retreat and the utility of a simple index to reveal such patterns.
Understanding the contribution of habitats and regional variation to long‐term population trends in tricolored blackbirds
Authors: Graves Emily E. , Holyoak Marcel , Rodd Kelsey T. , Meese Robert J. 
Published: July 2013

AbstractPopulation trends represent a minimum amount of information required to assess the conservation status of a species. However, understanding and detecting trends can be complicated by variation among habitats and regions, and by dispersal connecting habitats through source‐sink dynamics. We analyzed trends in breeding populations between habitats and regions to better understand the overall dynamics of a species' decline. Specifically, we analyzed historical trends in breeding populations of tricolored blackbirds (Agelaius tricolor) using breeding records from 1907 to 2009. The species breeds itinerantly and ephemerally uses multiple habitat types and breeding areas, which make interpretation of trends complex. We found overall abundance declines of 63% between 1935 and 1975. Since 1980 overall declines became nonsignificant and obscure despite large amounts of data from 1980 to 2009. Temporal trends differed between breeding habitat types and were associated with regional differences in population declines. A new habitat, triticale crops (a wheat‐rye hybrid grain) produced colonies 40× larger, on average, than other breeding habitats, and contributed to a change in regional distribution since it primarily occurred in a single region. The mechanism for such an effect is not clear, but could represent the local availability of foodstuffs in the landscape rather than something specific to triticale crops. While variation in trends among habitats clearly occurred, they could not easily be ascribed to source‐sink dynamics, ecological traps, habitat selection or other detailed ecological mechanisms. Nonetheless, such exchanges provide valuable information to guide management of dynamic systems.
Coupling hydraulic and biological measurements highlights the key influence of algal biofilm on infiltration basin performance
Authors: Gette‐Bouvarot Morgane , Mermillod‐Blondin Florian , Angulo‐Jaramillo Rafael , Delolme Cécile , Lemoine Damien , Lassabatere Laurent , Loizeau Sébastien , Volatier Laurence 
Published: July 2013

ABSTRACTInfiltration basins are increasingly used in urban areas for flood protection, groundwater recharge and storm water disposal. However, their operation is often affected by clogging, leading to degraded infiltration. The aim of this work was to evaluate the respective influences of sediment deposition and biofilm biomass on the deterioration of hydraulic performances in two infiltration basins used for groundwater recharge. Samples were collected by coring in the two basins. Grain size distribution (with and without organic matter), bacterial and algal biomasses, and microbial activity were measured at three depths from the soil surface (0–1 cm, 2–3 cm and 10–14 cm). In parallel, in situ single‐ring infiltration tests were performed before and after removal of the top layer (0–1 cm). The results showed considerably reduced permeability due to clogging of the top sedimentary layer in the two basins. The highest reduction of permeability was measured in the basin colonized by the largest algal biomass. The proportions of fine mineral particles (<63 µm) were comparable in the two basins and could not explain their differences in saturated hydraulic conductivities. In addition, the relationships between biological and hydraulic parameters highlighted a threshold effect of algal biomass on the structure of the pore network, possibly explaining the decrease in infiltration. This original link between hydraulic and microbial characteristics suggests that algal biofilm growth had a major impact on the hydraulic performance of the infiltration basins. Copyright © 2013 John Wiley & Sons, Ltd.
Transpiration and water relations of evergreen shrub species on an artificial landform for mine waste storage versus an adjacent natural site in semi‐arid Western Australia
Authors: Gwenzi Willis , Hinz Christoph , Bleby Timothy M. , Veneklaas Erik J. 
Published: July 2013

ABSTRACTIn water‐limited environments, transpiration may minimize deep drainage on engineered covers used for hazardous waste disposal. However, comparative studies investigating plant ecophysiology and water use on engineered covers and natural sites are limited. Water use patterns and plant–water relations of evergreen shrubs were monitored in semi‐arid Western Australia to (1) investigate the response of plant–water relations and shrub transpiration to soil moisture changes and (2) quantify stand transpiration and its contribution to the water balance. The shrubs showed conservative (<20 cm hr−1) but persistent transpiration. Differential response to rainfall pulses was evident among species; sap velocity for Acacia bivenosa and Acacia inaequilatera increased by 20–103% (p < 0·05) after rainfall events exceeding 15 mm but declined rapidly to pre‐storm levels. On the contrary, sap velocity for Acacia pruinocarpa increased by 61% after large pulse (83 and 127 mm) associated with cyclonic activity and remained high (10–15 cm hr−1) thereafter. These transpiration patterns suggested contrasting rooting patterns among the species. Sap velocity was low (<20 mm hr−1) for all species, even when moisture was readily available. Annual shrub transpiration was 65 (engineered cover) and 81 mm (natural shrubland), accounting for 16 and 20% of annual rainfall (395 mm). Stand characteristics, plant ecophysiology and shrub transpiration were comparable for both sites, demonstrating the importance of using topsoil as a growth medium and seedbank in revegetation. Overall, the study provided insights on ecophysiological behaviour of artificial landforms, and the first empirical evidence suggesting rapid and successful restoration of mined lands can be achieved under semi‐arid conditions. Copyright © 2013 John Wiley & Sons, Ltd.
Studies on a Wind Turbine Generating System that Employs a Thyristor Inverter
Authors: Nishikata Shoji , Tatsuta Fujio 
Published: July 2013

SummaryA new wind turbine generating system that employs a current‐source thyristor inverter is proposed, and the steady‐state and dynamic performances for a practical system are discussed. The proposed system is essentially based on the shaft generator system that is widely used in large ships, and it has many features such as high reliability and generation of output power of high quality. It is shown that electric power with constant frequency and voltage with low distortion can be obtained by using this novel system despite the changes in the velocity of natural wind. A dynamic model of the system is also developed, and a good agreement between simulated and experimental performances is obtained, thereby confirming the validity of the model.
Evaluation of Design Method for Engine Output Power and Battery Energy Capacity for Lithium‐Ion Battery Hybrid Diesel Railway Vehicles
Authors: Shiraki Naoki , Kondo Keiichiro 
Published: July 2013

SummaryDiesel engine lithium‐ion battery hybrid vehicles are attracting attention because the energy consumption during their operation and exhaust emissions can be reduced considerably. However, a reasonably accurate method of designing the engine power and battery energy has not yet been proposed, although the above‐mentioned type of traction system can help in realizing an environment‐friendly railway vehicle. In this paper, a design method for the battery energy capacity and engine output power is proposed in the case of a control strategy in which the sum of the kinetic energy of the vehicle and the battery energy is maintained constant. The proposed method is verified by the velocity/state of charge of the battery charts obtained in experimental tests. The proposed design method can be used to develop environment‐friendly railway traction systems for nonelectrified sections.