bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Hexagonal Covalent Porphyrin Framework as an Efficient Support for Gold Nanoparticles toward Catalytic Reduction of 4‐Nitrophenol
Authors: Ding Zheng‐Dong , Wang Yu‐Xia , Xi Sai‐Fei , Li Yunxing , Li Zaijun , Ren Xuehong , Gu Zhi‐Guo 
Published: October 2016

AbstractA hexagonal porphyrin‐based porous organic polymer, namely, CPF‐1, was constructed by 3+2 ketoenamine condensation of the C2‐symmetric porphyrin diamine 5,15‐bis(4‐aminophenyl)‐10,20‐diphenylporphyrin and 1,3,5‐triformylphloroglucinol. This material exhibits permanent porosity and excellent thermal and chemical stability. CPF‐1 can be employed as a superior supporting substrate to immobilize Au nanoparticles (NPs) as a result of the strong interactions between Au NPs and the CPF support. An Au@CPF‐1 hybrid was synthesized by an interfacial solution infiltration method with NaBH4 as reducing agent. Au NPs (5 nm) grew on CPF‐1 and were distributed without aggregation. Moreover, Au@CPF‐1 exhibits superior catalytic activity compared to many other reported Au‐based catalysts for the reduction of 4‐nitrophenol in the presence of NaBH4. In addition, Au@CPF‐1 has excellent stability and recyclability, and it can be reused for three successive reaction cycles without loss of activity. The dense distribution of phenyl rings on the channel walls of the CPF support can reasonably be regarded as the active sites that adsorb the 4‐nitrophenol molecule through hydrogen‐bonding and C−H⋅⋅⋅π interactions, as was confirmed by the X‐ray structure of model compound DAPP‐Benz.
Facile Light‐Mediated Preparation of Small Polymer‐Coated Palladium‐Nanoparticles and Their Application as Catalysts for Alkyne Semi‐Hydrogenation
Authors: Mäsing Florian , Wang Xi , Nüsse Harald , Klingauf Jürgen , Studer Armido 
Published: October 2016

AbstractA facile light‐mediated preparation of small palladium nanoparticles (PdNPs) with a diameter of 1.3 nm and low dispersity by using low‐priced and readily prepared photoactive polymers is presented. These polymers act as reagents for the photochemical reduction of Pd ions and they are also stabilizers for the PdNPs generated in situ. The PdNP–polymer hybrid materials prepared by this reliable approach are efficient hydrogenation catalysts that show high activity and Z‐selectivity in the semi‐hydrogenation of alkynes. These PdNP–catalyst hybrid materials can be readily recycled and reused up to five times.
Mechanical Behavior of Polymer Gels for RDCs and RCSAs Collection: NMR Imaging Study of Buckling Phenomena
Authors: Hellemann Erich , Teles Rubens R. , Hallwass Fernando , Barros W. , Navarro‐Vázquez Armando , Gil Roberto R. 
Published: October 2016

AbstractAnisotropic NMR parameters, such as residual dipolar couplings (RDCs), residual chemical shift anisotropies (RCSAs) and residual quadrupolar couplings (RQCs or ΔνQ), appear in solution‐state NMR when the molecules under study are subjected to a degree of order. The tunable alignment by reversible compression/relaxation of gels (PMMA and p‐HEMA) is an easy, user‐friendly, and very affordable method to measure them. When using this method, a fraction of isotropic NMR signals is observed in the NMR spectra, even at a maximum degree of compression. To explain the origin of these isotropic signals we decided to investigate their physical location inside the NMR tube using deuterium 1D imaging and MRI micro‐imaging experiments. It was observed that after a certain degree of compression the gels start to buckle and they generate pockets of isotropic solvent, which are never eliminated. The amount of buckling depends on the amount of cross‐linker and the length of the gel.
Phototriggered Supramolecular Polymerization
Authors: Pal Deep Sankar , Kar Haridas , Ghosh Suhrit 
Published: October 2016

AbstractPhoto‐initiated supramolecular polymerization of a naphthalenediimide (NDI‐1) derivative containing an ortho‐nitrobenzyl (ONB)‐protected amide group is demonstrated. In a hydrocarbon solvent (methylcyclohexane), it remains as monomer. Upon photo‐irradiation, deprotection of the ONB group produces NDI‐2 with a free amide group, which drives supramolecular polymerization by self‐complementary H‐bonding between the amide groups, leading to gelation. The polymerization rate can be controlled by tuning the energy of the light source. During photopolymerization, a gradual increase in hydrodynamic radius and viscosity is noticed. More interestingly, the morphology of the supramolecular polymer of NDI‐2, produced by photo‐irradiation, was a spherulite, which is in sharp contrast with the fibrillar morphology of NDI‐2 polymer, when assembled spontaneously without a phototrigger. This is ascribed to the ability of the ONB‐caged pro‐monomer (NDI‐1) to act as a chain‐stopper by forming a H‐bonded complex with the active monomer during the growth of the supramolecular polymer under photo‐irradiation.
Insertion of Isolated Alkynes into Carbon–Carbon σ‐Bonds of Unstrained Cyclic β‐Ketoesters via Transition‐Metal‐Free Tandem Reactions: Synthesis of Medium‐Sized Ring Compounds
Authors: Zhou Yuanyuan , Tao Xianghua , Yao Qiyi , Zhao Yulei , Li Yanzhong 
Published: October 2016

AbstractThe transition‐metal‐free insertion of isolated alkynes into carbon–carbon σ‐bonds of unstrained cyclic β‐dicarbonyl compounds has been reported. These tandem reactions offer an efficient synthesis of medium‐sized ring or fused‐ring compounds through ring expansion. The methodology has the potential to be widely used throughout organic synthesis due to the easily accessible starting materials and mild reaction conditions.
Calcium‐Catalyzed Synthesis of Polysubstituted 2‐Alkenylfurans from β‐Keto Esters Tethered to Propargyl Alcohols
Authors: Morcillo Sara P. , Leboeuf David , Bour Christophe , Gandon Vincent 
Published: October 2016

AbstractAn efficient synthesis of polysubstituted 2‐alkenylfurans using Ca(NTf2)2/KPF6 as a catalytic mixture is described. It is based on the cycloelimination of readily available propargyl alcohols tethered to β‐keto esters under dry conditions to avoid competitive Meyer–Schuster rearrangement. The furan can be further functionalized in situ by a calcium‐catalyzed Friedel–Crafts‐type reaction with secondary and tertiary alcohols. The title reaction allows for the high‐yielding preparation of di‐, tri‐, and tetrasubstituted 2‐alkenylfurans, which are important subunits of bioactive compounds.
Intramolecularly Coordinated Gallium Sulfides: Suitable Single Source Precursors for GaS Thin Films
Authors: Řičica Tomáš , Světlík Tomáš , Dostál Libor , Růžička Aleš , Růžička Květoslav , Beneš Ludvík , Němec Petr , Bouška Marek , Jambor Roman 
Published: October 2016

AbstractOur studies have been focused on the synthesis of N→Ga coordinated organogallium sulfides [L1Ga(μ‐S)]3 (1) and [L2Ga(μ‐S)]2 (2) containing either N,C,N‐ or C,N‐chelating ligands L1 or L2 (L1 is {2,6‐(Me2NCH2)2C6H3}− and L2 is {2‐(Et2NCH2)‐4,6‐tBu2‐C6H2}−). As the result of the different ligands, compounds 1 and 2 differ mutually in their structure. To change the Ga/S ratio, unusually N→Ga coordinated organogallium tetrasulfide L1Ga(κ2‐S4) (3) was prepared and the unprecedented complex [{2‐[CH{(CH2)3CH3}(μ‐OH)]‐6‐CH2NMe2}C6H3]GaS (4) was also isolated as the minor by‐product of the reaction. Compounds 1–3 were further studied as potential single‐source precursors for amorphous GaS thin film deposition by spin‐coating.
Tailorable PC71BM Isomers: Using the Most Prevalent Electron Acceptor to Obtain High‐Performance Polymer Solar Cells
Authors: Zhan Xin‐Xing , Zhang Xin , Dai Si‐Min , Li Shu‐Hui , Lu Xu‐Zhai , Deng Lin‐Long , Xie Su‐Yuan , Huang Rong‐Bin , Zheng Lan‐Sun 
Published: October 2016

AbstractDespite being widely used as electron acceptor in polymer solar cells, commercially available PC71BM (phenyl‐C71‐butyric acid methyl ester) usually has a “random” composition of mixed regioisomers or stereoisomers. Here PC71BM has been isolated into three typical isomers, α‐, β1‐ and β2‐PC71BM, to establish the isomer‐dependent photovoltaic performance on changing the ternary composition of α‐, β1‐ and β2‐PC71BM. Mixing the isomers in a ratio of α/β1/β2=8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC71BM as photoactive layer (PTB7=poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]]). The three typical PC71BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average‐performing PCE of 1.28–7.44 % due to diverse self‐aggregation of individual or mixed PC71BM isomers in the otherwise same polymer solar cells.
Metal Complexes for Two‐Photon Photodynamic Therapy: A Cyclometallated Iridium Complex Induces Two‐Photon Photosensitization of Cancer Cells under Near‐IR Light
Authors: McKenzie Luke K. , Sazanovich Igor V. , Baggaley Elizabeth , Bonneau Mickaële , Guerchais Véronique , Williams J. A. Gareth , Weinstein Julia A. , Bryant Helen E. 
Published: October 2016

AbstractPhotodynamic therapy (PDT) uses photosensitizers (PS) which only become cytotoxic upon light‐irradiation. Transition‐metal complexes are highly promising PS due to long excited‐state lifetimes, and high photo‐stabilities. However, these complexes usually absorb higher‐energy UV/Vis light, whereas the optimal tissue transparency is in the lower‐energy NIR region. Two‐photon excitation (TPE) can overcome this dichotomy, with simultaneous absorption of two lower‐energy NIR‐photons populating the same PS‐active excited state as one higher‐energy photon. We introduce two low‐molecular weight, long‐lived and photo‐stable iridium complexes of the [Ir(N^C)2(N^N)]+ family with high TP‐absorption, which localise to mitochondria and lysosomal structures in live cells. The compounds are efficient PS under 1‐photon irradiation (405 nm) resulting in apoptotic cell death in diverse cancer cell lines at low light doses (3.6 J cm−2), low concentrations, and photo‐indexes greater than 555. Remarkably 1 also displays high PS activity killing cancer cells under NIR two‐photon excitation (760 nm), which along with its photo‐stability indicates potential future clinical application.
Insights into the Ring‐Opening of Biomass‐Derived Furanics over Carbon‐Supported Ruthenium
Authors: Gilkey Matthew J. , Mironenko Alexander V. , Yang Leerang , Vlachos Dionisios G. , Xu Bingjun 
Published: October 2016

AbstractThe selective ring‐opening of cellulose‐derived furanic molecules is a promising pathway for the production of industrially relevant linear oxygenates, such as 1,6‐hexanediol. 2,5‐Dimethylfuran (DMF) is employed as a model compound in a combined experimental and computational investigation to provide insights into the metal‐catalyzed ring‐opening. Ring‐opening to 2‐hexanol and 2‐hexanone and ring‐saturation to 2,5‐dimethyltetrahydrofuran (DMTHF) are identified as two main parallel pathways. DFT calculations and microkinetic modeling indicate that DMF adsorbs on Ru in an open‐ring configuration, which is potentially a common surface intermediate that leads to both ring‐opening and ring‐saturation products. Although the activation barriers for the two pathways are comparable, the formation of DMTHF is more thermodynamically favorable. In addition, steric interactions with co‐adsorbed 2‐propoxyl, derived from the solvent, and the oxophilic nature of Ru play key roles to determine the product distribution: the former favors less bulky, that is, ring‐closed, intermediates, and the latter retards O−H bond formation. Finally, we show that the hydrodeoxygenation of oxygenated furanics, such as 5‐methylfurfural and (5‐methyl‐2‐furyl)methanol, on Ru occurs preferentially at oxygen‐containing side groups to form DMF, followed by either ring‐opening or ring‐saturation.
Marmoset vocal communication: Behavior and neurobiology
Authors: Eliades Steven J. , Miller Cory T. 
Published: October 2016

ABSTRACTThere has been recent increasing interest in the use of marmosets, a New World primate species, as a model in biomedical research. One of the principal advantages of marmosets as a research model is their rich vocal repertoire and communicative vocal behaviors displayed both in the wild and in captivity. Studies of this species' vocal communication system have the potential to reveal the evolutionary underpinnings of human speech, and therefore are of interest to the neuroscience and biology research communities. Here a recent research into the behavioral and neurobiological basis of marmoset vocal communication was reviewed and they argued for their broader value as a neuroscientific model. They discuss potential avenues for future research including developmental neurobiology and the application of modern molecular tools to the study of primate communication. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 286–299, 2017
Weight, shape, and muscularity concerns in male and female adolescents: Predictors of change and influences on eating concern
Authors: Hoffmann Svenja , Warschburger Petra 
Published: October 2016

ABSTRACTObjectiveThe purpose of this study was to examine the impact of age and weight status on adolescents' body dissatisfaction and its change over 20 months in a gender‐comparing design. The influence of body image concern on eating concern was also investigated.MethodIn a prospective study, 675 male and female adolescents aged 12–16 were assessed using self‐report questionnaires on weight, shape, muscularity, and eating concerns. Height and weight measurements were taken by trained personnel. Data were analyzed using structural equation modeling.ResultsAnalyses of latent means revealed more pronounced weight/shape concern in females than males and more pronounced muscularity concern in males than females. Weight/shape concern increased in females over time, whereas muscularity concern remained stable in both genders. Baseline levels of weight/shape concern could be predicted by age and weight status in females and by weight status in males. The only predictor of change in weight/shape concern was weight status in males. Baseline levels of muscularity concern could be predicted by age in females and by weight status in males. Similar effects were found for changes in muscularity concern in both genders. Increases in weight/shape and muscularity concern were associated with more pronounced eating concern.DiscussionThe results confirm gender differences in distinctive facets of body image concern and its prediction. The relevance of increase in body image concern in adolescents is underlined by its association with eating concern in both genders. Further explanatory variables for change in body dissatisfaction should be examined in future studies. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:139–147)
Microbial community responses to soil tillage and crop rotation in a corn/soybean agroecosystem
Authors: Smith Chris R. , Blair Peter L. , Boyd Charlie , Cody Brianne , Hazel Alexander , Hedrick Ashley , Kathuria Hitesh , Khurana Parul , Kramer Brent , Muterspaw Kristin , Peck Charles , Sells Emily , Skinner Jessica , Tegeler Cara , Wolfe Zoe 
Published: October 2016

AbstractThe acreage planted in corn and soybean crops is vast, and these crops contribute substantially to the world economy. The agricultural practices employed for farming these crops have major effects on ecosystem health at a worldwide scale. The microbial communities living in agricultural soils significantly contribute to nutrient uptake and cycling and can have both positive and negative impacts on the crops growing with them. In this study, we examined the impact of the crop planted and soil tillage on nutrient levels, microbial communities, and the biochemical pathways present in the soil. We found that farming practice, that is conventional tillage versus no‐till, had a much greater impact on nearly everything measured compared to the crop planted. No‐till fields tended to have higher nutrient levels and distinct microbial communities. Moreover, no‐till fields had more DNA sequences associated with key nitrogen cycle processes, suggesting that the microbial communities were more active in cycling nitrogen. Our results indicate that tilling of agricultural soil may magnify the degree of nutrient waste and runoff by altering nutrient cycles through changes to microbial communities. Currently, a minority of acreage is maintained without tillage despite clear benefits to soil nutrient levels, and a decrease in nutrient runoff—both of which have ecosystem‐level effects and both direct and indirect effects on humans and other organisms.
Nitrogen cycling and export in California chaparral: the role of climate in shaping ecosystem responses to fire
Authors: Hanan Erin J. , Tague Christina (Naomi) , Schimel Joshua P. 
Published: October 2016

AbstractClimate change models predict that interannual rainfall variability will increase in California over the next several decades; these changes will likely influence how frequently California ecosystems burn and how they respond to fire. Fires uncouple N mobilization from uptake by destroying plant biomass and increasing nitrification. Following fire, autumn and winter rains can leach N into streams from slopes that have been denuded. The amount of N exported depends on how rapidly soil microbes metabolize it into mobile forms such as , and the rate that recovering plants take up available N. However, the long‐term effects of a changing climate on postfire N dynamics remain unknown. We used the ecohydrologic model RHESSys (regional hydro‐ecologic simulation system) to evaluate how interannual climate variability may affect the magnitude of N mineralization, nitrification, N export, and plant recovery following fire. N export was highest when fire was followed by drought; even though there was less water moving through the system, dry conditions prolonged the period during which N mobilization was decoupled from plant uptake. We also found that the effects of drought on N export were magnified in stands dominated by obligate seeders, which initially recovered more slowly than resprouters. These findings suggest that climate may regulate N balance most powerfully by influencing how quickly plants “turn on” and begin to immobilize N.
Spatial and environmental processes show temporal variation in the structuring of waterbird metacommunities
Authors: Henry Dominic A. W. , Cumming Graeme S. 
Published: October 2016

AbstractMetacommunity theory provides a framework for assessing the role of spatial and environmental processes in structuring ecological communities and places emphasis on the role of dispersal. Four metacommunity perspectives have been proposed: species‐sorting, patch dynamics, mass effects, and a neutral model. Metacommunity analysis decomposes the variance in communities into regional and local dynamics and ascribes it to one of these perspectives, although they are not always mutually exclusive. Although birds are a well‐studied taxon, consensus around processes structuring freshwater avian metacommunities is lacking and few studies have repeated samples through time. We used variance partitioning to analyze waterbird community data collected over seven sampling periods at 60 wetland sites in KwaZulu‐Natal, South Africa, to distinguish the processes driving beta‐diversity and identify which metacommunity perspective(s) best explained these patterns. We addressed two focal questions: (1) how do environmental, spatial, and spatially structured environmental components contribute to variance in the waterbird community; and (2) given a significant contribution, which environmental variables were most important in explaining metacommunity structure? We also investigated the role of temporal variation in community processes by comparing results across sampling periods. The underlying landscape was characterized by four groups of environmental variables: vegetation structure, water quality, rainfall, and land cover. Moran's eigenvector maps were used to generate a set of multiscale spatial predictor variables. Our results showed that the spatially structured environmental component was dominant through the sampling periods. Purely spatial and environmental components contributed a significant proportion of variance, but their magnitudes showed considerable temporal variation. Environmental processes were more pronounced in winter periods while purely spatial processes were augmented in the summer months. Our results suggest that species‐sorting is the primary structuring forces in waterbird communities. The presence of spatial effects, especially in summer, does however suggest that species‐sorting does not operate in isolation. Future efforts also need to address the causes and consequences of temporal variation in metacommunity processes.
Management of forest regeneration in boreal and temperate deer–forest systems: challenges, guidelines, and research gaps
Authors: Beguin Julien , Tremblay Jean‐Pierre , Thiffault Nelson , Pothier David , Côté Steeve D. 
Published: October 2016

AbstractHeavy browsing pressure from large ungulates is a multicontinent phenomenon that causes regeneration failure of many palatable tree species and induces important socioeconomic and ecological impacts in forest ecosystems. The development of forest management practices that address adequately this issue, however, remains scarce and challenging because (1) large herbivores are both a resource and a source of disturbance; (2) the management of forests and ungulate populations remains largely disconnected in practice; and (3) we still lack a good understanding of the role of critical factors, especially deer densities, vegetation attributes, and their interactions, on the magnitude of browsing damages on forest regeneration. We bring new insights into these challenging issues by critically reviewing the current methods used by managers and conservationists to mitigate deer impacts on forest regeneration, emphasizing the spatial scale at which these methods are undertaken. Specifically, we review management actions at multiple scales on both deer populations (e.g., hunting) and vegetation (e.g., silvicultural treatments) that are common to most deer–forest systems and, for that reason, deserve priority investigation. We identify strengths and limitations of current management actions and highlight the main research gaps. Based on this review, we propose a new integrated management scheme that explicitly addresses: (1) the integration and prioritization of management actions, (2) the development of adaptive management plans, and (3) the participation of stakeholders. Conflicting demands by different stakeholders have challenged the effectiveness of management strategies in deer–forest systems. To reverse this situation, we advocate for a shift of paradigm and the development of integrated strategies that (1) bridge the gap between management actions and the design of in situ experiments and (2) coordinate actions at multiple spatial scales on both deer populations and forests. We propose a new framework informed by key objectives and grounded in the adaptive management paradigm to support this transition, and suggest a research agenda for the next decade(s).