bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Highly Active System for the Metal‐Free Aerobic Photocyanation of Tertiary Amines with Visible Light: Application to the Synthesis of Tetraponerines and Crispine A
Authors: Orejarena Pacheco Julio Cesar , Lipp Alexander , Nauth Alexander M. , Acke Fabian , Dietz Jule‐Philipp , Opatz Till 
Published: March 2016

AbstractA highly efficient metal‐free catalytic system for the aerobic photocyanation of tertiary amines with visible light is reported. The use of air as terminal oxidant offers an improved safety profile compared with pure oxygen, the used compact fluorescent lamp (CFL) light sources are highly economical, and no halogenated solvents are required. This system not only proves to be effective for a wide variety of trialkylamines, pharmaceuticals, and alkaloids but remarkably also allows the lowest catalyst loading (0.00001 mol % or 0.1 ppm) ever reported for an organic dye. Bruylants reactions and C‐alkylation/decyanations were performed on the obtained α‐aminonitriles to demonstrate the postfunctionalization of complex molecules. The catalytic system is furthermore applied in the short and effective syntheses of the alkaloids (±)‐crispine A and the tetraponerines T7 and T8.
Synthesis and Evaluation of a 2,11‐Cembranoid‐Inspired Library
Authors: Welford Amanda J , Caldwell John J. , Liu Manjuan , Richards Meirion , Brown Nathan , Lomas Cara , Tizzard Graham J. , Pitak Mateusz B. , Coles Simon J. , Eccles Suzanne A. , Raynaud Florence I. , Collins Ian 
Published: March 2016

AbstractThe 2,11‐cembranoid family of natural products has been used as inspiration for the synthesis of a structurally simplified, functionally diverse library of octahydroisobenzofuran‐based compounds designed to augment a typical medicinal chemistry library screen. Ring‐closing metathesis, lactonisation and SmI2‐mediated methods were exemplified and applied to the installation of a third ring to mimic the nine‐membered ring of the 2,11‐cembranoids. The library was assessed for aqueous solubility and permeability, with a chemical‐space analysis performed for comparison to the family of cembranoid natural products and a sample set of a screening library. Preliminary investigations in cancer cells showed that the simpler scaffolds could recapitulate the reported anti‐migratory activity of the natural products.
Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts
Authors: Siddiki S. M. A. Hakim , Touchy Abeda Sultana , Kon Kenichi , Shimizu Ken‐ichi 
Published: March 2016

AbstractCarbon‐supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant‐free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate‐limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method.
A Versatile One‐Pot Access to Cyanoarenes from ortho‐ and para‐Quinones: Paving the Way for Cyanated Functional Materials
Authors: Glöcklhofer Florian , Lunzer Markus , Stöger Berthold , Fröhlich Johannes 
Published: March 2016

AbstractA generally applicable direct synthesis of cyanoarenes from quinones is presented. Particular emphasis is placed on the preparation of precursors and target molecules relevant for organic materials, including halogenated cyanoarenes and larger cyanated acenes. The reaction and work‐up protocols are adjusted for the challenges presented by the different substrates and products. Screening results of the initial reaction optimization are given to further facilitate adaptation to other synthetic problems. The universality of the reaction is finally highlighted by successful substitution of para‐quinones by an ortho‐quinone as the starting material.
Method for the quantification of rupture probability in soft collagenous tissues
Authors: Balzani D. , Schmidt T. , Ortiz M. 
Published: March 2016

SummaryA computational method is presented for the assessment of rupture probabilities in soft collagenous tissues. This may in particular be important for the quantitative analysis of medical diseases such as atherosclerotic arteries or abdominal aortic aneurysms, where an unidentified rupture has in most cases fatal consequences. The method is based on the numerical minimization and maximization of probabilities of failure, which arise from random input quantities, for example, tissue properties. Instead of assuming probability distributions for these quantities, which are typically unknown especially for soft collagenous tissues, only restricted knowledge of these distributions is taken into account. Given this limited statistical input data, the minimized/maximized probabilities represent optimal bounds on the rupture probability, which enable a quantitative estimation of potential risks of performing or not performing medical treatment. Although easily extendable to all kinds of mechanical rupture criteria, the approach presented here incorporates stretch‐based and damage‐based criteria. These are evaluated based on numerical simulations of loaded tissues, where continuum mechanical material formulations are considered, which capture the supra‐physiological behavior of soft collagenous tissues. Numerical examples are provided demonstrating the applicability of the method in an overstretched atherosclerotic artery. Copyright © 2016 John Wiley & Sons, Ltd.
Spectroscopic Monitoring of Mechanical Forces during Protein Folding by using Molecular Force Probes
Authors: Stauch Tim , Hoffmann Marvin T. , Dreuw Andreas 
Published: March 2016

AbstractDetailed folding pathways of proteins are still largely unknown. Real‐time monitoring of mechanical forces acting in proteins during structural transitions would provide deep insights into these highly complex processes. Here, we propose two molecular force probes that can be incorporated into the protein backbone to gain insight into the magnitude and direction of mechanical forces acting in proteins during natural folding and unfolding through their optical spectroscopic response. In fact, changes in the infrared and Raman spectra are proportional to the mechanical force deforming the force probes, and the relevant bands can be intensified and shifted to a transparent window in the protein spectrum by isotopic substitution. As a result, the proposed molecular force probes can act as “force rulers”, allowing the spectroscopic observation and measurement of mechanical forces acting within the proteins under natural conditions without external perturbation.
Free‐Electron Gas Spectrum Uniqueness in the Mixture of Noble Gases
Authors: Stanković K. , Alimpijević M. 
Published: March 2016

AbstractGas mixtures can reach the Maxwell's specter shape in case of low‐ionized mono‐atomic mixtures in the weak electric field. The parameters pertaining to the Maxwell spectrum of free electrons' gas straightforwardly settle on the insulating characteristics of the examined gas mixture at the fundamental level. In this paper, a condition for breakdown has been accomplished taking as a starting point the ionization coefficients derived accordingly, as well as the conditions for breakdown in keeping with the Townsend mechanism. The dc breakdown voltage value of noble gases mixture has been measured in the experimental part of the paper. The hypothesis that the free‐electron gas spectrum is unique in the noble gas mixture and is of Maxwell's type has been verified. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of Ionization waves in an Atmospheric‐Pressure Micro‐Plasma Jet
Authors: Talviste R. , Jõgi I. , Raud J. , Paris P. 
Published: March 2016

AbstractPresent study investigated the development of ionization waves in an atmospheric‐pressure plasma jet. Plasma was ignited by 6 kHz sinusoidal voltage applied to a cylindrical electrode surrounding the 500 μm inner diameter quartz tube and positioned 10 mm upstream from the tube orifice. The plasma current was observed using a plane electrode placed 20 mm downstream from the tube orifice. The spatial development of ionization waves was monitored by registering the optical emission along the axis of the tube. At voltages in range of 5.5 ‐ 7.5 kV only one pulse occurred during positive half‐period while at higher voltages the number of pulses increased up to 6 ‐ 7 per half‐period. The development of the first and subsequent pulses during one half‐period was essentially different. For the first pulse the sharp rise of optical emission characterizing the front of the ionization wave occurred initially near the high‐voltage electrode and moved towards the tube orifice and further in the He jet. The propagation of ionization wave coincided with the rise of the displacement current measured at the plane electrode. For subsequent ionization waves of the same half‐period, the emission occurred initially at the tube orifice and the ionization wave developed simultaneously in two directions: towards the high‐voltage electrode and towards the end of the jet. The velocity of ionization wave inside the tube was in range of (2. 5 ‐ 5.0) · 104 m/s for first wave and as high as 1.2 · 105 m/s for subsequent waves. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatiotemporal Evolution of Intense Short Gaussian Laser Pulses in Weakly Relativistic Magnetized Plasma
Authors: Olumi M. , Maraghechi B. 
Published: March 2016

AbstractThe weakly relativistic regime of propagation of a short and intense laser pulse in the magnetized plasma is investigated. By considering relativistic nonlinearity and using non‐linear Schrödinger equation with paraxial approximation, two second‐order coupled differential equations are obtained for the longitudinal pulse width parameter (in time) and for the transverse pulse width parameter (in space). The simultaneous evolution of spot size and length of a relativistic Gaussian laser pulse in a magnetized plasma can be calculated by the numerical solution of the equations. The effect of magnetic field is investigated. It is observed that in the presence of magnetic field both the self‐compression and the self‐focusing can be enhanced. Furthermore, the interplay between the longitudinal self‐compression and the transverse self‐focusing in a magnetized plasma is investigated. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Landscape characteristics and livestock presence influence common ravens: relevance to greater sage‐grouse conservation
Authors: Coates Peter S. , Brussee Brianne E. , Howe Kristy B. , Gustafson Kit Benjamin , Casazza Michael L. , Delehanty David J. 
Published: March 2016

AbstractCommon raven (Corvus corax; hereafter, raven) population abundance in the sagebrush steppe of the American West has increased threefold during the previous four decades, largely as a result of unintended resource subsidies from human land‐use practices. This is concerning because ravens frequently depredate nests of species of conservation concern, such as greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse). Grazing by livestock in sagebrush ecosystems is common practice on most public lands, but associations between livestock and ravens are poorly understood. The primary objective of this study was to identify the effects of livestock on raven occurrence while accounting for landscape characteristics within human‐altered sagebrush steppe habitat, particularly in areas occupied by breeding sage‐grouse. Using data from southeastern Idaho collected during spring and summer across 3 yr, we modeled raven occurrence as a function of the presence of livestock while accounting for multiple landscape covariates, including land cover features, topographical features, and proximity to sage‐grouse lek sites (breeding grounds), as well as site‐level anthropogenic features. While accounting for landscape characteristics, we found that the odds of raven occurrence increased 45.8% in areas where livestock were present. In addition, ravens selected areas near sage‐grouse leks, with the odds of occurrence decreasing 8.9% for every 1‐km distance, increase away from the lek. We did not find an association between livestock use and distance to lek. We also found that ravens selected sites with relatively lower elevation containing increased amounts of cropland, wet meadow, and urbanization. Limiting raven access to key anthropogenic subsidies and spatially segregating livestock from sage‐grouse breeding areas would likely reduce exposure of predatory ravens to sage‐grouse nests and chicks.
Relationships among spring flow, habitats, and fishes within evolutionary refugia of the Edwards Plateau
Authors: Craig Cody A. , Kollaus Kristy A. , Behen Kenneth P. K. , Bonner Timothy H. 
Published: March 2016

AbstractAquifers and spring complexes within the arid and semi‐arid karst Edwards Plateau region of Texas are evolutionary refugia supporting a large number of endemic flora and fauna. Spring fishes, many of which are endemic, are associated with the spring complexes, whereas river fishes generally avoid spring complexes. Purposes of this study were to experimentally test affinities of spring fishes and river fishes for spring complexes and rivers among six independent spring‐river systems of the Edwards Plateau and to quantitate relationship among spring fishes, river fishes and spring flow magnitude within spring complexes. We found that spring fishes did not exclusively use spring complexes but were more abundant in spring complexes than rivers and that species richness, relative abundance, and density of spring fishes were directly related to spring flow magnitude. Patterns in affinities for river fishes were less distinct. Quantitation of fish–habitat relationships will assist efforts in conserving aquatic resources within the Edwards Plateau and provides predictive models to assess biological integrity of other spring complexes. In addition, consistency in distributional patterns of spring and river fishes provides a framework for testing underlying processes of species segregation and diversification, establishes boundaries of aquatic evolutionary refugia, and expands the value of evolutionary refugia from historical refugia to contemporary and future refugia for Edwards Plateau aquatic biota.
The amplitude of dead wood resource pulses produced by plantation thinning mediates the assembly of wood‐boring beetles
Authors: Thibault Monic , Moreau Gaétan 
Published: March 2016

AbstractThe commercial thinning of forests creates a dead wood resource pulse in the form of tree tops, branches, and stumps that are used by many organisms as a substrate but are also increasingly coveted as a source of bioenergy. To evaluate the effects of commercial thinning, as well as those of woody debris (WD) harvest, retention or supplementation on communities of cerambycids (Coleoptera: Cerambycidae), a family of saprophagous wood‐boring beetles, a 3‐yr study was carried out in white spruce plantations subjected to three contrasting thinning regimes. The regimes included a standard commercial thinning, a thinning with biomass removal, and a thinning with added standing dead wood. Beetles were captured starting the first summer following treatment using flight intercept traps, and the volume of standing and downedWDwas estimated using quadrats. The results indicated that the complex of 25 cerambycid species was influenced by commercial thinning, by the time elapsed since thinning treatments were carried out, and by the abundance of freshWD. A higher abundance and species richness of cerambycids was documented in thinning treatments yielding greater volumes of dead wood; compared to unthinned areas, cerambycid beetle richness was 116% higher in thinned areas where woody biomass was harvested, while it was 200–233% higher in thinned areas with dead wood retention or supplementation. This suggests that dead wood resource pulses caused by plantation thinning have a strong, beneficial effect on cerambycid communities that wanes as the amount of harvesting debris remaining on site decreases.
Temporal‐ and density‐dependent impacts of an invasive plant on pollinators and pollination services to a native plant
Authors: Herron‐Sweet Christina R. , Lehnhoff Erik A. , Burkle Laura A. , Littlefield Jeffrey L. , Mangold Jane M. 
Published: March 2016

AbstractPollinators and pollination services are under threat globally, and invasive plants have been implicated in their decline. Results of previous studies suggest that consequences of invasion for pollinators and plant–pollinator interactions are context specific. Investigating factors such as the density of an invasive plant and its phenology may provide a nuanced understanding of invasive species impacts. We conducted a 2‐yr study in Montana to investigate how local pollinator abundance, richness, community composition, and visitation patterns varied with invasive Centaura stoebe density and phenology, and whether C. stoebe altered the reproduction of a co‐flowering native plant, Heterotheca villosa, through changes in pollinator visitation. In an observational study, we found that during its peak bloom in August, Centaurea stoebe provided abundant floral resources to late‐season pollinators. However, prior to C. stoebe bloom, native floral density and pollinator abundance and richness of these plots were lower compared to plots where C. stoebe was low or absent. Pollinator community composition in plots without C. stoebe was different compared to plots with C. stoebe (both high and low C. stoebe density), and these differences in pollinator composition strongly depended on the time of season. In an experimental study, we found that there was little evidence of competition between C. stoebe and H. villosa for pollinators at low relative densities of C. stoebe. Using experimental pollen supplementation, we observed no evidence of pollen limitation of seed set in H. villosa with increasing density of experimentally added C. stoebe. Our results suggest that the impact of an invasive plant on pollinators and plant–pollinator interactions depends on the relative density of the invasive plant and the timing of its bloom. Differences in pollinator visitation patterns over the growing season suggest that although C. stoebe provides abundant resources to late‐season pollinators, displacement of native plants at high C. stoebe density may indirectly harm pollinators that are active before C. stoebe blooms or that prefer native plants. Based on our results, restricting C. stoebe to low densities may help mitigate negative repercussions to native plant reproduction and may even be beneficial to some pollinators.
Emergent effects of structural complexity and temperature on predator–prey interactions
Authors: Wasserman Ryan J. , Alexander Mhairi E. , Weyl Olaf L. F. , Barrios‐O'Neill Daniel , Froneman P. William , Dalu Tatenda 
Published: March 2016

AbstractEphemeral aquatic environments are important habitats for a variety of species. They are highly variable with regards to vegetation structure and physico‐chemical features that potentially mediate outcomes of biotic interactions. Multiple environmental variables and their emergent impacts on the relationship between prey consumption rate by a predator and prey density (functional response), however, are rarely assessed. Here, we investigated the combined effects of temperature and habitat complexity on the functional response of the freshwater predatory notonectidEnithares sobriaon the cladoceran prey organismDaphnia longispina. A TypeIIfunctional response was observed forE. sobriapredating onD. longispinaand while temperature and habitat complexity had no effect on the response type, these environmental variables interacted with consequences for the magnitude of the functional responses. Overall, structural complexity favored the predator as greater consumption was observed in the most complex habitat treatment. Temperature effects were also evident although these effects were not unidirectional with regard to treatment factor gradients as predators were the most successful at intermediary temperatures. Furthermore, there was a complex interplay between habitat complexity and temperature, with attack rates being greatest at low and high complexities within intermediate temperatures, while at zero complexity attack rates were greatest at the lowest temperature. The effect of habitat on handling times was only evident in the low temperature treatments which decreased steadily with each increase in complexity. Through the application of functional responses the synergistic effects of multiple environmental drivers on predator–prey interaction outcomes have been highlighted, adding insight into how interactions among species may be affected by natural or artificially induced environmental variability.
Abandonment of croplands: problem or chance for grassland restoration? case studies from hungary
Authors: Valkó Orsolya , Deák Balázs , Török Péter , Kelemen András , Miglécz Tamás , Tóth Katalin , Tóthmérész Béla 
Published: March 2016

Abstract
In Central‐ and Eastern Europe, the collapse of socialist regimes resulted in a transformation of state‐owned agricultural cooperatives to privately owned lands from the early 1990s onwards. These socioeconomic processes resulted in landscape‐scale changes in biodiversity, ecosystem services and agricultural production. In parallel, large‐scale abandonment of croplands, especially on sandy, salty or frequently inundated areas, became common. Abandoned croplands are usually sensitive to species invasions, and are hotspots of noxious weeds, posing threats both to agriculture and nature conservation. Grassland restoration on former croplands can be an effective strategy for suppressing these species. Thus, a common goal of nature conservation and agriculture can be the restoration of grasslands on former croplands to (1) suppress weed and/or invasive species in line with the policy “Good Farming Practices”, (2) support animal husbandry by creating meadows or pastures, and to (3) recover biodiversity and ecosystem services. In the present paper we report “best practices” of grassland restoration projects from Hungary. Our aim was to compare the effectiveness of spontaneous grassland recovery vs. active grassland restoration by seed sowing in terms of the recovery of biodiversity and ecosystem services, such as weed control and biomass production. Our results showed that grassland restoration on abandoned fields offers a viable solution for restoring biodiversity and ecosystem services. Seed sowing ensures higher weed control and biomass production, but results in lower biodiversity compared to spontaneous recovery. Both restoration methods can be cost‐effective, or even profitable even within a relatively short period of a nature conservation project.