bluuebunny/crossref_metadata_2025 huggingface dataset:
Diastereoselective Synthesis of and Mechanistic Understanding for the Formation of 2‐Piperidinones from Imines and Cyano‐Substituted Anhydrides
Authors: Di Maso Michael J. , Snyder Kevin M. , De Souza Fernandes Fábio , Pattawong Ommidala , Tan Darlene Q. , Fettinger James C. , Cheong Paul Ha‐Yeon , Shaw Jared T.
Published: March 2016

2‐Piperidinones are synthesized in a single step from imines and 2‐cyano glutaric anhydrides. The reaction provides the products in good diastereoselectivity and generates a quaternary stereogenic center. Substitutions on the anhydride skeleton are well tolerated to provide 2‐piperidinones with three stereogenic centers from a single transformation. The pertinent transition structures have also been computed using quantum mechanics and reveal the key interactions controlling the stereochemical outcome of the reaction.
Tetraphenylethene‐Based Conjugated Fluoranthene: A Potential Fluorescent Probe for Detection of Nitroaromatic Compounds
Authors: Chandrasekaran Yogesh , Venkatramaiah Nutalapati , Patil Satish
Published: March 2016

This study reports the synthesis and photophysical properties of a star‐shaped, novel, fluoranthene–tetraphenylethene (TFPE) conjugated luminogen, which exhibits aggregation‐induced blue‐shifted emission (AIBSE). The bulky fluoranthene units at the periphery prevent intramolecular rotation (IMR) of phenyl rings and induces a blueshift with enhanced emission. The AIBSE phenomenon was investigated by solvatochromic and temperature‐dependent emission studies. Nanoaggregates of TFPE, formed by varying the water/THF ratio, were investigated by SEM and TEM and correlated with optical properties. The TFPE conjugate was found to be a promising fluorescent probe towards the detection of nitroaromatic compounds (NACs), especially for 2,4,6‐trinitrophenol (PA) with high sensitivity and a high Stern–Volmer quenching constant. The study reveals that nanoaggregates of TFPE formed at 30 and 70 % water in THF showed unprecedented sensitivity with detection limits of 0.8 and 0.5 ppb, respectively. The nanoaggregates formed at water fractions of 30 and 70 % exhibit high Stern–Volmer constants (Ksv=79 998 and 51 120 m−1, respectively) towards PA. Fluorescence quenching is ascribed to photoinduced electron transfer between TFPE and NACs with a static quenching mechanism. Test strips coated with TFPE luminogen demonstrate fast and ultra‐low‐level detection of PA for real‐time field analysis.
Planar Chiral, Ferrocene‐Stabilized Silicon Cations
Authors: Schmidt Ruth K. , Klare Hendrik F. T. , Fröhlich Roland , Oestreich Martin
Published: March 2016

The preparation of a series of planar chiral, ferrocenyl‐substituted hydrosilanes as precursors of ferrocene‐stabilized silicon cations is described. These molecules also feature stereogenicity at the silicon atom. The generation and 29Si NMR spectroscopic characterization of the corresponding silicon cations is reported, and problems arising from interactions of the electron‐deficient silicon atom and adjacent C(sp3)−H bonds or aromatic π donors are discussed. These issues are overcome by tethering another substituent at the silicon atom to the ferrocene backbone. The resulting annulation also imparts conformational rigidity and steric hindrance in such a way that the central chirality at the silicon atom is set with complete diastereocontrol. These chiral Lewis acid catalysts were then tested in difficult Diels–Alder reactions, but no enantioinduction was seen.
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

A 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

The 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

Carbon‐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

A 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.
Evaluating the effectiveness of transferrin receptor‐1 (TfR1) as a magnetic resonance reporter gene
Authors: Pereira Sofia M. , Herrmann Anne , Moss Diana , Poptani Harish , Williams Steve R. , Murray Patricia , Taylor Arthur
Published: March 2016

Magnetic resonance (MR) reporter genes have the potential for tracking the biodistribution and fate of cells in vivo, thus allowing the safety, efficacy and mechanisms of action of cell‐based therapies to be comprehensively assessed. In this study, we evaluate the effectiveness of the iron importer transferrin receptor‐1 (TfR1) as an MR reporter gene in the model cell line CHO‐K1. Overexpression of the TfR1 transgene led to a reduction in the levels of endogenous TfR1 mRNA, but to a 60‐fold increase in total TfR1 protein levels. Although the mRNA levels of ferritin heavy chain‐1 (Fth1) did not change, Fth1 protein levels increased 13‐fold. The concentration of intracellular iron increased significantly, even when cells were cultured in medium that was not supplemented with iron and the amount of iron in the extracellular environment was thus at physiological levels. However, we found that, by supplementing the cell culture medium with ferric citrate, a comparable degree of iron uptake and MR contrast could be achieved in control cells that did not express the TfR1 transgene. Sufficient MR contrast to enable the cells to be detected in vivo following their administration into the midbrain of chick embryos was obtained irrespective of the reporter gene. We conclude that TfR1 is not an effective reporter and that, to track the biodistribution of cells with MR imaging in the short term, it is sufficient to simply culture cells in the presence of ferric citrate. Copyright © 2016 The Authors Contrast Media & Molecular Imaging Published by John Wiley & Sons Ltd.
Method for the quantification of rupture probability in soft collagenous tissues
Authors: Balzani D. , Schmidt T. , Ortiz M.
Published: March 2016

A 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

Detailed 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

Gas 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

Present 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

The 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

Common 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

Aquifers 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

The 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

Pollinators 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

Ephemeral 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

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.
The First Structurally Characterised Example of Silicon in an S6 Coordination Sphere
Authors: Marckwordt Annemarie , Rajasekharan‐Nair Rajeev , Steel Graham , Kennedy Alan R. , Reglinski John , Spicer Mark D.
Published: March 2016

The reaction of sodium hydro‐tris(phenylthioimidazolyl)borate (NaTmPh) with silicon tetraiodide gives rise to the first crystallographically characterised molecular silicon compounds, [Si(TmPh)2] 2X (X = I– and I3–), in which the silicon is found in a regular S6 environment. The [Si(TmPh)2]2+ cation is subjected to analysis using DFT methods to explain why an S6 coordination motif is preferred to an S4 coordination motif.
Deciphering glycomics and neuroproteomic alterations in experimental traumatic brain injury: Comparative analysis of aspirin and clopidogrel treatment
Authors: Abou‐Abbass Hussein , Bahmad Hisham , Abou‐El‐Hassan Hadi , Zhu Rui , Zhou Shiyue , Dong Xue , Hamade Eva , Mallah Khalil , Zebian Abir , Ramadan Naify , Mondello Stefania , Fares Jawad , Comair Youssef , Atweh Samir , Darwish Hala , Zibara Kazem , Mechref Yehia , Kobeissy Firas
Published: March 2016

As populations age, the number of patients sustaining traumatic brain injury (TBI) and concomitantly receiving preinjury antiplatelet therapy such as aspirin (ASA) and clopidogrel (CLOP) is rising. These drugs have been linked with unfavorable clinical outcomes following TBI, where the exact mechanism(s) involved are still unknown. In this novel work, we aimed to identify and compare the altered proteome profile imposed by ASA and CLOP when administered alone or in combination, prior to experimental TBI. Furthermore, we assessed differential glycosylation PTM patterns following experimental controlled cortical impact model of TBI, ASA, CLOP, and ASA + CLOP. Ipsilateral cortical brain tissues were harvested 48 h postinjury and were analyzed using an advanced neuroproteomics LC‐MS/MS platform to assess proteomic and glycoproteins alterations. Of interest, differential proteins pertaining to each group (22 in TBI, 41 in TBI + ASA, 44 in TBI + CLOP, and 34 in TBI + ASA + CLOP) were revealed. Advanced bioinformatics/systems biology and clustering analyses were performed to evaluate biological networks and protein interaction maps illustrating molecular pathways involved in the experimental conditions. Results have indicated that proteins involved in neuroprotective cellular pathways were upregulated in the ASA and CLOP groups when given separately. However, ASA + CLOP administration revealed enrichment in biological pathways relevant to inflammation and proinjury mechanisms. Moreover, results showed differential upregulation of glycoproteins levels in the sialylated N‐glycans PTMs that can be implicated in pathological changes. Omics data obtained have provided molecular insights of the underlying mechanisms that can be translated into clinical bedside settings.
Risk‐based seismic design for collapse safety
Authors: Sinković Nuša Lazar , Brozovič Marko , Dolšek Matjaž
Published: March 2016

Risk‐based seismic design, as introduced in this paper, involves the use of different types of analysis in order to satisfy a risk‐based performance objective with a reasonable utilization rate and sufficient reliability. Differentiation of the reliability of design can be achieved by defining different design algorithms depending on the importance of a structure. In general, the proposed design is iterative, where the adjustment of a structure during iterations is the most challenging task. Rather than using automated design algorithms, an attempt has been made to introduce three simple guidelines for adjusting reinforced concrete frames in order to increase their strength and deformation capacity. It is shown that an engineer can design a reinforced concrete frame in a few iterations, for example, by adjusting the structure on the basis of pushover analysis and checking the final design by means of nonlinear dynamic analysis. A possible variant of the risk‐based design algorithm for the collapse safety of reinforced concrete frame buildings is proposed, and its application is demonstrated by means of an example of an eight‐storey reinforced concrete building. Four iterations were required in order to achieve the risk‐based performance objective with a reasonable utilization rate. Copyright © 2016 John Wiley & Sons, Ltd.
The fetch effect on aeolian sediment transport on a sandy beach: a case study from Magilligan Strand, Northern Ireland
Authors: Lynch Kevin , Jackson Derek W. T. , Cooper J. Andrew G.
Published: March 2016

Experiments were conducted on Magilligan Strand, Northern Ireland, to assess the influence of the fetch effect on aeolian sediment transport. During each experiment surface sediments were uniformly dry and unhindered by vegetation or debris. The leading edge of erodible material was well defined, with the limit of wave up‐rush demarcating the wet–dry boundary; the work was conducted during low tides. A number of electronic and integrating traps were utilised, with two ultrasonic anemometers used to measure wind direction and velocity at 1 Hz. The combination of 1o direction data and trap locations resulted in a range of fetch distances, from 2 to 26 m. Data integrated over 15‐minute intervals (corresponding to the integrating trap data) revealed a distinct trend for all the experiments. An initial rapid increase in the transport rate occurred over a short distance (4–9 m). This maximum transport rate was maintained for a further 5–6 m before a steady decay in the flux followed, as fetch distance increased. A measured reduction in wind speed (6–8%) across the beach suggests a negative feedback mechanism may be responsible for the diminishing transport rate: the saltating grains induce energy dissipation, thus reducing the capability of the wind to maintain transport. For one experiment, the presence of compact sediment patches may also have contributed to the reduction of the transport rate. The decay trend calls into question the utility of the fetch effect as an important parameter in aeolian studies that seek to understand sediment budgets of the foredune‐beach zone. Copyright © 2016 John Wiley & Sons, Ltd.
Using phenocams to monitor our changing Earth: toward a global phenocam network
Authors: Brown Tim B , Hultine Kevin R , Steltzer Heidi , Denny Ellen G , Denslow Michael W , Granados Joel , Henderson Sandra , Moore David , Nagai Shin , SanClements Michael , Sánchez‐Azofeifa Arturo , Sonnentag Oliver , Tazik David , Richardson Andrew D
Published: March 2016

Rapid changes to the biosphere are altering ecological processes worldwide. Developing informed policies for mitigating the impacts of environmental change requires an exponential increase in the quantity, diversity, and resolution of field‐collected data, which, in turn, necessitates greater reliance on innovative technologies to monitor ecological processes across local to global scales. Automated digital time‐lapse cameras – “phenocams” – can monitor vegetation status and environmental changes over long periods of time. Phenocams are ideal for documenting changes in phenology, snow cover, fire frequency, and other disturbance events. However, effective monitoring of global environmental change with phenocams requires adoption of data standards. New continental‐scale ecological research networks, such as the US National Ecological Observatory Network (NEON) and the European Union's Integrated Carbon Observation System (ICOS), can serve as templates for developing rigorous data standards and extending the utility of phenocam data through standardized ground‐truthing. Open‐source tools for analysis, visualization, and collaboration will make phenocam data more widely usable.
Extinction of experience: the loss of human–nature interactions
Authors: Soga Masashi , Gaston Kevin J
Published: March 2016

Increasingly, people are becoming less likely to have direct contact with nature (natural environments and their associated wildlife) in their everyday lives. Over 20 years ago, Robert M Pyle termed this ongoing alienation the “extinction of experience”, but the phenomenon has continued to receive surprisingly limited attention. Here, we present current understanding of the extinction of experience, with particular emphasis on its causes and consequences, and suggest future research directions. Our review illustrates that the loss of interaction with nature not only diminishes a wide range of benefits relating to health and well‐being, but also discourages positive emotions, attitudes, and behavior with regard to the environment, implying a cycle of disaffection toward nature. Such serious implications highlight the importance of reconnecting people with nature, as well as focusing research and public policy on addressing and improving awareness of the extinction of experience.
Ein thermisch‐mechanisches Stoffmodell für Steinsalz mit Berücksichtigung von Schädigung, Bruch und Verheilung
Authors: Missal Christian , Gährken Andreas , Stahlmann Joachim
Published: March 2016

Aktuell werden Grubengebäude im Steinsalz für die Endlagerung von schwach‐ und mittelradioaktiven oder chemotoxischen Abfällen genutzt. Um für diese Grubengebäude Aussagen zur Integrität der Barriere zu machen oder um geotechnische Abdichtungsbauwerke zu bemessen, sind numerische Werkzeuge erforderlich. Am Institut für Grundbau und Bodenmechanik der Technischen Universität Braunschweig ist für Prognoseberechnungen das Stoffmodell TUBSsalt entwickelt worden. Die Formulierung des Stoffmodells erlaubt die Abbildung der wesentlichen Kriechvorgänge sowie der Phänomene Schädigung, Bruch und Verheilung. Ebenso wird der Einfluss der Temperatur auf das mechanische Verhalten berücksichtigt. Die erforderlichen Parameter können anhand von Laborversuchen bestimmt werden. Die Implementierung des Stoffmodells erfolgte in zwei unterschiedlichen numerischen Programmsystemen der Methode der Finiten Elemente und der Methode der Finiten Differenzen. Mit einem einheitlichen Parametersatz für einen Salztyp kann eine gute Übereinstimmung zwischen den berechneten Daten und den Versuchsergebnissen erzielt werden. Um ein vielseitiges und zuverlässiges Werkzeug zur Bemessung von Hohlräumen im Salzgebirge zu erhalten, wird die Validierung des Stoffmodells auch an komplexeren Strukturen fortgesetzt.

A thermal‐mechanical constitutive model for rock salt with consideration of damage, failure and healing. Numerous mine workings in rock salt are used in the present for the disposal of low and intermediate level radioactive waste or chemo‐toxic waste. In order to get information about the integrity of the mine workings' barrier or to calculate geotechnical sealing structures, numerical tools are necessary. For this purpose, the constitutive model TUBSsalt was developed at the Institute for Soil Mechanics and Foundation Engineering of the Technische Universität Braunschweig. The constitutive model's formulation enables the simulation of the significant creeping mechanisms as well as damage, failure and healing. The influence of the temperature on the mechanical behavior is also considered. The parameters can be determined by laboratory tests. The implementation of the constitutive model is realized in two different numerical program systems. By using a uniform set of parameters for a type of salt a good match between the calculated data and the measured data can be achieved. In order to get a versatile and reliable tool for the calculation of cavities in rock salt, the validation of the constitutive model will be continued with more complex structures.
Combining tract‐ and atlas‐based analysis reveals microstructural abnormalities in early Tourette syndrome children
Authors: Wen Hongwei , Liu Yue , Wang Jieqiong , Rekik Islem , Zhang Jishui , Zhang Yue , Tian Hongwei , Peng Yun , He Huiguang
Published: March 2016

Tourette syndrome (TS) is a neurological disorder that causes uncontrolled repetitive motor and vocal tics in children. Examining the neural basis of TS churned out different research studies that advanced our understanding of the brain pathways involved in its development. Particularly, growing evidence points to abnormalities within the fronto‐striato‐thalamic pathways. In this study, we combined Tract‐Based Spatial Statistics (TBSS) and Atlas‐based regions of interest (ROI) analysis approach, to investigate the microstructural diffusion changes in both deep and superficial white matter (SWM) in TS children. We then characterized the altered microstructure of white matter in 27 TS children in comparison with 27 age‐ and gender‐matched healthy controls. We found that fractional anisotropy (FA) decreases and radial diffusivity (RD) increases in deep white matter (DWM) tracts in cortico‐striato‐thalamo‐cortical (CSTC) circuit as well as SWM. Furthermore, we found that lower FA values and higher RD values in white matter regions are correlated with more severe tics, but not tics duration. Besides, we also found both axial diffusivity and mean diffusivity increase using Atlas‐based ROI analysis. Our work may suggest that microstructural diffusion changes in white matter is not only restricted to the gray matter of CSTC circuit but also affects SWM within the primary motor and somatosensory cortex, commissural and association fibers. Hum Brain Mapp 37:1903–1919, 2016. © 2016 Wiley Periodicals, Inc.
Issues in Distance Education: A Primer for Higher Education Decision Makers
Authors: Beaudoin Michael
Published: March 2016

This chapter presents an overview of current issues related to distance learning in higher education. It identifies central questions, issues, challenges, and opportunities that must be addressed by decision makers, as well as key attributes of effective leaders.
Learner and Faculty Support
Authors: Guan Sharon , Stanford Daniel
Published: March 2016

This chapter identifies effective ways to address learner and faculty support. It introduces methods for building a successful learner support system by providing sufficient resources and proactively addressing learner motivation. It also addresses effective faculty support through institutional policies, resources, training, and course development.
The Role of Medial Temporal Lobe Regions in Incidental and Intentional Retrieval of Item and Relational Information in Aging
Authors: Wang Wei‐Chun , Giovanello Kelly S.
Published: March 2016

Considerable neuropsychological and neuroimaging work indicates that the medial temporal lobes are critical for both item and relational memory retrieval. However, there remain outstanding issues in the literature, namely the extent to which medial temporal lobe regions are differentially recruited during incidental and intentional retrieval of item and relational information, and the extent to which aging may affect these neural substrates. The current fMRI study sought to address these questions; participants incidentally encoded word pairs embedded in sentences and incidental item and relational retrieval were assessed through speeded reading of intact, rearranged, and new word‐pair sentences, while intentional item and relational retrieval were assessed through old/new associative recognition of a separate set of intact, rearranged, and new word pairs. Results indicated that, in both younger and older adults, anterior hippocampus and perirhinal cortex indexed incidental and intentional item retrieval in the same manner. In contrast, posterior hippocampus supported incidental and intentional relational retrieval in both age groups and an adjacent cluster in posterior hippocampus was recruited during both forms of relational retrieval for older, but not younger, adults. Our findings suggest that while medial temporal lobe regions do not differentiate between incidental and intentional forms of retrieval, there are distinct roles for anterior and posterior medial temporal lobe regions during retrieval of item and relational information, respectively, and further indicate that posterior regions may, under certain conditions, be over‐recruited in healthy aging. © 2016 Wiley Periodicals, Inc.
State Prices of Conditional Quantiles: New Evidence on Time Variation in the Pricing Kernel
Authors: Metaxoglou Konstantinos , Smith Aaron
Published: March 2016

We develop a set of statistics to represent the option‐implied stochastic discount factor and we apply them to S&P 500 returns between 1990 and 2012. Our statistics, which we call state prices of conditional quantiles (SPOCQ), estimate the market's willingness to pay for insurance against outcomes in various quantiles of the return distribution. By estimating state prices at conditional quantiles, we separate variation in the shape of the pricing kernel from variation in the probability of a particular event. Thus, without imposing strong assumptions about the distribution of returns, we obtain a novel view of pricing‐kernel dynamics. We document six features of SPOCQ for the S&P 500. Most notably, and in contrast to recent studies, we find that the price of downside risk decreases when volatility increases. Under a standard asset pricing model, this result implies that most changes in volatility stem from fluctuations in idiosyncratic risk. Consistent with this interpretation, no known systematic risk factors such as consumer sentiment, liquidity or macroeconomic risk can account for the negative relationship between the price of downside risk and volatility. Copyright © 2016 John Wiley & Sons, Ltd.
A comparative evaluation of diffuse reflectance and Raman spectroscopy in the detection of cervical cancer
Authors: Shaikh Rubina , Prabitha Vasumathi G. , Dora Tapas Kumar , Chopra Supriya , Maheshwari Amita , Deodhar Kedar , Rekhi Bharat , Sukumar Nita , Krishna C. Murali , Subhash Narayanan
Published: March 2016

Optical spectroscopic techniques show improved diagnostic accuracy for non‐invasive detection of cervical cancers. In this study, sensitivity and specificity of two in vivo modalities, i.e diffuse reflectance spectroscopy (DRS) and Raman spectroscopy (RS), were compared by utilizing spectra recorded from the same sites (67 tumor (T), 22 normal cervix (C), and 57 normal vagina (V)). Data was analysed using principal component – linear discriminant analysis (PC‐LDA), and validated using leave‐one‐out‐cross‐validation (LOOCV). Sensitivity, specificity, positive predictive value and negative predictive value for classification between normal (N) and tumor (T) sites were 91%, 96%, 95% and 93%, respectively for RS and 85%, 95%, 93% and 88%, respectively for DRS. Even though DRS revealed slightly lower diagnostic accuracies, owing to its lower cost and portability, it was found to be more suited for cervical cancer screening in low resource settings. On the other hand, RS based devices could be ideal for screening patients with centralised facilities in developing countries.

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