bluuebunny/crossref_metadata_2025 huggingface dataset:
Burden and predictors ofStaphylococcus aureusandS. pseudintermediusinfections among dogs presented at an academic veterinary hospital in South Africa (2007–2012)
Authors: Qekwana Daniel N. , Oguttu James Wabwire , Sithole Fortune , Odoi Agricola
Published: April 2017

Background

Staphylococci are commensals of the mucosal surface and skin of humans and animals, but have been implicated in infections such as otitis externa, pyoderma, urinary tract infections and post-surgical complications. Laboratory records provide useful information to help investigate these infections. Therefore, the objective of this study was to investigate the burdens of these infections and use multinomial regression to examine the associations between variousStaphylococcusinfections and demographic and temporal factors among dogs admitted to an academic veterinary hospital in South Africa.

Methods

Records of 1,497 clinical canine samples submitted to the bacteriology laboratory at a veterinary academic hospital between 2007 and 2012 were included in this study. Proportions of staphylococcal positive samples were calculated, and a multinomial logistic regression model was used to identify predictors of staphylococcal infections.

Results

Twenty-seven percent of the samples tested positive forStaphylococcusspp. The species ofStaphylococcusidentified wereS. pseudintermedius(19.0%),S. aureus(3.8%),S. epidermidis(0.7%) andS. felis(0.1%). The remaining 2.87% consisted of unspeciatedStaphylococcus. Distribution of the species by age of dog showed thatS. pseudintermediuswas the most common (25.6%) in dogs aged 2–4 years whileS. aureuswas most frequent (6.3%) in dogs aged 5–6 years.S. pseudintermedius(34.1%) andS. aureus(35.1%) were the most frequently isolated species from skin samples. The results of the multivariable multinomial logistic regression model identified specimen, year and age of the dog as significant predictors of the risk of infection withStaphylococcus. There was a significant temporal increase (RRR = 1.17; 95% CI [1.06–1.29]) in the likelihood of a dog testing positive forS. pseudintermediuscompared to testing negative. Dogs ≤ 8 years of age were significantly more likely to test positive forS. aureusthan those >8 years of age. Similarly, dogs between 2–8 years of age were significantly more likely to test positive forS. pseudintermediusthan those >8 years of age. In addition, dogs 2–4 years of age (RRR = 1.83; 1.09–3.06) were significantly more likely to test positive forS. pseudintermediuscompared to those <2 years of age. The risk of infection withS. pseudintermediusorS. aureuswas significantly higher in ear canal and skin specimens compared to other specimens.

Conclusions

The findings suggest thatS. pseudintermediusandS. aureuswere the most commonly isolated species from dogs presented at the study hospital. Age of the dog and the location of infection were significant predictors of infection with bothStaphylococcusspecies investigated. Significant increasing temporal trend was observed forS. pseudintermediusbut notS. aureus. This information is useful for guiding clinical decisions as well as future research.
Ventilation versus biology: What is the controlling mechanism of nitrous oxide distribution in the North Atlantic?
Authors: de la Paz Mercedes , García‐Ibáñez Maribel I. , Steinfeldt Reiner , Ríos Aida F. , Pérez Fiz F.
Published: April 2017

The extent to which water mass mixing and ocean ventilation contribute to nitrous oxide (N2O) distribution at the scale of oceanic basins is poorly constrained. We used novel N2O and chlorofluorocarbon measurements along with multiparameter water mass analysis to evaluate the impact of water mass mixing and Atlantic Meridional Overturning Circulation (AMOC) on N2O distribution along the Observatoire de la variabilité interannuelle et décennale en Atlantique Nord (OVIDE) section, extending from Portugal to Greenland. The biological N2O production has a stronger impact on the observed N2O concentrations in the water masses traveling northward in the upper limb of the AMOC than those in recently ventilated cold water masses in the lower limb, where N2O concentrations reflect the colder temperatures. The high N2O tongue, with concentrations as high as 16 nmol kg−1, propagates above the isopycnal surface delimiting the upper and lower AMOC limbs, which extends from the eastern North Atlantic Basin to the Iceland Basin and coincides with the maximum N2O production rates. Water mixing and basin‐scale remineralization account for 72% of variation in the observed distribution of N2O. The mixing‐corrected stoichiometric ratio N2O:O2 for the North Atlantic Basin of 0.06 nmol/μmol is in agreement with ratios of N2O:O2 for local N2O anomalies, suggesting than up to 28% of N2O production occurs in the temperate and subpolar Atlantic, an overlooked region for N2O cycling. Overall, our results highlight the importance of taking into account mixing, O2 undersaturation when water masses are formed and the increasing atmospheric N2O concentrations when parameterizing N2O:O2 and biological N2O production in the global oceans.
Increased ice flow in Western Palmer Land linked to ocean melting
Authors: Hogg Anna E. , Shepherd Andrew , Cornford Stephen L. , Briggs Kate H. , Gourmelen Noel , Graham Jennifer A. , Joughin Ian , Mouginot Jeremie , Nagler Thomas , Payne Antony J. , Rignot Eric , Wuite Jan
Published: April 2017

A decrease in the mass and volume of Western Palmer Land has raised the prospect that ice speed has increased in this marine‐based sector of Antarctica. To assess this possibility, we measure ice velocity over 25 years using satellite imagery and an optimized modeling approach. More than 30 unnamed outlet glaciers drain the 800 km coastline of Western Palmer Land at speeds ranging from 0.5 to 2.5 m/d, interspersed with near‐stagnant ice. Between 1992 and 2015, most of the outlet glaciers sped up by 0.2 to 0.3 m/d, leading to a 13% increase in ice flow and a 15 km3/yr increase in ice discharge across the sector as a whole. Speedup is greatest where glaciers are grounded more than 300 m below sea level, consistent with a loss of buttressing caused by ice shelf thinning in a region of shoaling warm circumpolar water.
Clustering statistics, roughness feedbacks, and randomness in experimental step‐pool morphodynamics
Authors: Johnson Joel P. L.
Published: April 2017

Step pools are a common bed morphology in boulder‐rich gravel streams, but predicting how mountainous landscapes will respond to environmental perturbations such as climate‐related hydrological changes requires a better understanding of channel morphodynamics and factors that influence bed stability. Flume experiments exploring bed stabilization demonstrate feedbacks among surface roughness, coarse grain clustering, and surface grain size. Clustering is quantified by using a novel normalization of Ripley's K statistic designed for use in power law functions. At 95% confidence, many but not all beds stabilized with coarse grains becoming more clustered than complete spatial randomness. The clustering statistic predicts hydraulic roughness better than D84 does (the diameter at which 84% of grains are smaller), suggesting that the spatial organization of the bed can be a stronger control than grain size on flow hydraulics. Initial conditions affect the degree of clustering at stability, indicating sensitivity to history.
Improved moving window cross‐spectral analysis for resolving large temporal seismic velocity changes in permafrost
Authors: James S. R. , Knox H. A. , Abbott R. E. , Screaton E. J.
Published: April 2017

Cross correlations of seismic noise can potentially record large changes in subsurface velocity due to permafrost dynamics and be valuable for long‐term Arctic monitoring. We applied seismic interferometry, using moving window cross‐spectral analysis (MWCS), to 2 years of ambient noise data recorded in central Alaska to investigate whether seismic noise could be used to quantify relative velocity changes due to seasonal active‐layer dynamics. The large velocity changes (>75%) between frozen and thawed soil caused prevalent cycle‐skipping which made the method unusable in this setting. We developed an improved MWCS procedure which uses a moving reference to measure daily velocity variations that are then accumulated to recover the full seasonal change. This approach reduced cycle‐skipping and recovered a seasonal trend that corresponded well with the timing of active‐layer freeze and thaw. This improvement opens the possibility of measuring large velocity changes by using MWCS and permafrost monitoring by using ambient noise.
Quasi‐biennial oscillations in the geomagnetic field: Their global characteristics and origin
Authors: Ou Jiaming , Du Aimin , Finlay Christopher C.
Published: April 2017

Quasi‐biennial oscillations (QBOs), with periods in the range 1–3 years, have been persistently observed in the geomagnetic field. They provide unique information on the mechanisms by which magnetospheric and ionospheric current systems are modulated on interannual timescales and are also of crucial importance in studies of rapid core field variations. In this paper, we document the global characteristics of the geomagnetic QBO, using ground‐based data collected by geomagnetic observatories between 1985 and 2010, and reexamine the origin of the signals. Fast Fourier transform analysis of second‐order derivatives of the geomagnetic X, Y, and Z components reveals salient QBO signals at periods of 1.3, 1.7, 2.2, 2.9, and 5.0 years, with the most prominent peak at 2.2 years. The signature of geomagnetic QBO is generally stronger in the X and Z components and with larger amplitudes on geomagnetically disturbed days. The amplitude of the QBO in the X component decreases from the equator to the poles, then shows a local maximum at subauroral and auroral zones. The QBO in the Z component enhances from low latitudes toward the polar regions. At high latitudes (poleward of 50°) the geomagnetic QBO exhibits stronger amplitudes during LT 00:00–06:00, depending strongly on the geomagnetic activity level, while at low latitudes the main effect is in the afternoon sector. These results indicate that the QBOs at low‐to‐middle latitudes and at high latitudes are influenced by different magnetospheric and ionospheric current systems. The characteristics of the multiple peaks in the QBO range are found to display similar latitudinal and local time distributions, suggesting that these oscillations are derived from a common source. The features, including the strong amplitudes seen on disturbed days and during postmidnight sectors, and the results from spherical harmonic analysis, verify that the majority of geomagnetic QBO is of external origin. We furthermore find a very high correlation between the geomagnetic QBO and the QBOs in solar wind speed and solar wind dynamic pressure. This suggests the geomagnetic QBO primarily originates from the current systems due to the solar wind‐magnetosphere‐ionosphere coupling process.
Lagrangian and Eulerian characterization of two counter‐rotating submesoscale eddies in a western boundary current
Authors: Mantovanelli Alessandra , Keating Shane , Wyatt Lucy R. , Roughan Moninya , Schaeffer Amandine
Published: April 2017

In recent decades, high‐spatial resolution ocean radar and satellite imagery measurements have revealed a complex tangle of submesoscale filaments and eddies, in the surface velocity, temperature, and chlorophyll a fields. We use a suite of high‐resolution data to characterize two counter‐rotating, short‐lived eddies formed at the front between the warm East Australian Current (EAC) and temperate coastal waters (30°S, Eastern Australia). In this region, submesoscale filaments and short‐lived eddies are dynamically generated and decay at time scales of hours to days. Dominant cyclonic filaments of O(1) Rossby number formed along frontal jets and eddy boundaries, generating localized ageostrophic circulations at the submesoscale. Measurements of over‐ocean wind direction and surface currents from high‐frequency radars reveal the influence of the short‐term, small‐scale wind forcing on the surface circulation, enhancement of the horizontal shear, frontal jet destabilization, and the generation and decay of the cyclonic eddy. By contrast, the anticyclonic eddy formation was most likely associated with EAC mesoscale instability and anticyclonic vorticity. Lagrangian tracks show that surface particles can be temporarily trapped in the eddies and frontal convergent zones, limiting their transport. Mixing between EAC‐derived and coastal waters was increased along the frontal regions, and particles starting at the divergent regions around the eddies experienced significant dispersion at submesoscales. The cyclonic cold‐core eddy entrained high chlorophyll a shelf waters on its convergent side, suggesting spiral eddy cyclogenesis.
Small‐scale open ocean currents have large effects on wind wave heights
Authors: Ardhuin Fabrice , Gille Sarah T. , Menemenlis Dimitris , Rocha Cesar B. , Rascle Nicolas , Chapron Bertrand , Gula Jonathan , Molemaker Jeroen
Published: April 2017

Tidal currents and large‐scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts, and filaments at scales 10–100 km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of
times the current spectrum, where
is the spatially averaged significant wave height,
is the energy‐averaged period, and g is the gravity acceleration. This variability induced by currents has been largely overlooked in spite of its relevance for extreme wave heights and remote sensing.
Mixing rates and vertical heat fluxes north of Svalbard from Arctic winter to spring
Authors: Meyer Amelie , Fer Ilker , Sundfjord Arild , Peterson Algot K.
Published: April 2017

Mixing and heat flux rates collected in the Eurasian Basin north of Svalbard during the N‐ICE2015 drift expedition are presented. The observations cover the deep Nansen Basin, the Svalbard continental slope, and the shallow Yermak Plateau from winter to summer. Mean quiescent winter heat flux values in the Nansen Basin are 2 W m−2 at the ice‐ocean interface, 3 W m−2 in the pycnocline, and 1 W m−2 below the pycnocline. Large heat fluxes exceeding 300 W m−2 are observed in the late spring close to the surface over the Yermak Plateau. The data consisting of 588 microstructure profiles and 50 days of high‐resolution under‐ice turbulence measurements are used to quantify the impact of several forcing factors on turbulent dissipation and heat flux rates. Wind forcing increases turbulent dissipation seven times in the upper 50 m, and doubles heat fluxes at the ice‐ocean interface. The presence of warm Atlantic Water close to the surface increases the temperature gradient in the water column, leading to enhanced heat flux rates within the pycnocline. Steep topography consistently enhances dissipation rates by a factor of four and episodically increases heat flux at depth. It is, however, the combination of storms and shallow Atlantic Water that leads to the highest heat flux rates observed: ice‐ocean interface heat fluxes average 100 W m−2 during peak events and are associated with rapid basal sea ice melt, reaching 25 cm/d.
Short‐crested waves in the surf zone
Authors: Wei Zhangping , Dalrymple Robert A. , Xu Munan , Garnier Roland , Derakhti Morteza
Published: April 2017

This study investigates short‐crested waves in the surf zone by using the mesh‐free Smoothed Particle Hydrodynamics model, GPUSPH. The short‐crested waves are created by generating intersecting wave trains in a numerical wave basin with a beach. We first validate the numerical model for short‐crested waves by comparison with large‐scale laboratory measurements. Then short‐crested wave breaking over a planar beach is studied comprehensively. We observe rip currents as discussed in Dalrymple (1975) and undertow created by synchronous intersecting waves. The wave breaking of the short‐crested wavefield created by the nonlinear superposition of intersecting waves and wave‐current interaction result in the formation of isolated breakers at the ends of breaking wave crests. Wave amplitude diffraction at these isolated breakers gives rise to an increase in the alongshore wave number in the inner surf zone. Moreover, 3‐D vortices and multiple circulation cells with a rotation frequency much lower than the incident wave frequency are observed across the outer surf zone to the beach. Finally, we investigate vertical vorticity generation under short‐crested wave breaking and find that breaking of short‐crested waves generates vorticity as pointed out by Peregrine (1998). Vorticity generation is not only observed under short‐crested waves with a limited number of wave components but also under directional wave spectra.
Reproducibility of total ozone column monitoring by the Arosa Brewer spectrophotometer triad
Authors: Stübi R. , Schill H. , Klausen J. , Vuilleumier L. , Ruffieux D.
Published: April 2017

The historical review of the total ozone column measurements with the Arosa Brewer triad in operation since 1998 is presented. The calibration history of the different instruments and the data quality control performed at Arosa are described. Over the last 15 years, the Brewer triad shows a dispersion of ∼0.4% between the three collocated instruments and a long‐term stability of ±0.5%. These values are a reference metric achievable with well‐maintained Brewer instruments under favorable measurement conditions.
Effects of climate change on probable maximum precipitation: A sensitivity study over the Alabama‐Coosa‐Tallapoosa River Basin
Authors: Rastogi Deeksha , Kao Shih‐Chieh , Ashfaq Moetasim , Mei Rui , Kabela Erik D. , Gangrade Sudershan , Naz Bibi S. , Preston Benjamin L. , Singh Nagendra , Anantharaj Valentine G.
Published: April 2017

Probable maximum precipitation (PMP), defined as the largest rainfall depth that could physically occur under a series of adverse atmospheric conditions, has been an important design criterion for critical infrastructures such as dams and nuclear power plants. To understand how PMP may respond to projected future climate forcings, we used a physics‐based numerical weather simulation model to estimate PMP across various durations and areas over the Alabama‐Coosa‐Tallapoosa (ACT) River Basin in the southeastern United States. Six sets of Weather Research and Forecasting (WRF) model experiments driven by both reanalysis and global climate model projections, with a total of 120 storms, were conducted. The depth‐area‐duration relationship was derived for each set of WRF simulations and compared with the conventional PMP estimates. Our results showed that PMP driven by projected future climate forcings is higher than 1981–2010 baseline values by around 20% in the 2021–2050 near‐future and 44% in the 2071–2100 far‐future periods. The additional sensitivity simulations of background air temperature warming also showed an enhancement of PMP, suggesting that atmospheric warming could be one important factor controlling the increase in PMP. In light of the projected increase in precipitation extremes under a warming environment, the reasonableness and role of PMP deserve more in‐depth examination.
An intercomparison and validation of satellite‐based surface radiative energy flux estimates over the Arctic
Authors: Riihelä Aku , Key Jeffrey R. , Meirink Jan Fokke , Kuipers Munneke Peter , Palo Timo , Karlsson Karl‐Göran
Published: April 2017

Accurate determination of radiative energy fluxes over the Arctic is of crucial importance for understanding atmosphere‐surface interactions, melt and refreezing cycles of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite‐based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative flux estimates from Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1‐degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water Cycle Experiment (GEWEX) surface energy budget, and our own experimental FluxNet / Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg flux estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave flux in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave flux over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer‐based GEWEX and FluxNet‐CLARA flux estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the FluxNet‐CLARA downwelling shortwave flux is shown to be an overestimated cloud optical thickness. The results illustrate that satellite‐based flux estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in flux retrievals.
Big Ship Data: Using vessel measurements to improve estimates of temperature and wind speed on the Great Lakes
Authors: Fries Kevin , Kerkez Branko
Published: April 2017

The sheer size of many water systems challenges the ability of in situ sensor networks to resolve spatiotemporal variability of hydrologic processes. New sources of vastly distributed and mobile measurements are, however, emerging to potentially fill these observational gaps. This paper poses the question: How can nontraditional measurements, such as those made by volunteer ship captains, be used to improve hydrometeorological estimates across large surface water systems? We answer this question through the analysis of one of the largest such data sets: an unprecedented collection of one million unique measurements made by ships on the North American Great Lakes from 2006 to 2014. We introduce a flexible probabilistic framework, which can be used to integrate ship measurements, or other sets of irregular point measurements, into contiguous data sets. The performance of this framework is validated through the development of a new ship‐based spatial data product of water temperature, air temperature, and wind speed across the Great Lakes. An analysis of the final data product suggests that the availability of measurements across the Great Lakes will continue to play a large role in the confidence with which these large surface water systems can be studied and modeled. We discuss how this general and flexible approach can be applied to similar data sets, and how it will be of use to those seeking to merge large collections of measurements with other sources of data, such as physical models or remotely sensed products.
Competition between outer zone electron scattering by plasmaspheric hiss and magnetosonic waves
Authors: Ni Binbin , Hua Man , Zhou Ruoxian , Yi Juan , Fu Song
Published: April 2017

We quantify the electron scattering effects of simultaneous plasmaspheric hiss and magnetosonic waves that occurred in two neighboring time intervals but with distinct wave intensity profiles on 21 August 2013. Their combined scattering is found capable of causing electron distribution variations largely distinguishable from the consequences of individual waves. The net effect of electron diffusion relies strongly on the relative dominance of the two wave intensities, which also controls the relative contribution of each wave mode. In combination, MS waves slow down the hiss‐induced loss of ~100 keV electrons, and hiss efficiently inhibits the electron butterfly distribution caused by MS waves to produce a gradual acceleration process. Our results strongly suggest that comprehensive simulations of the radiation belt electron dynamics should carefully incorporate the combined scattering and complex competition resulting from simultaneous occurrences of various magnetospheric emissions, including, but not limited to, plamaspheric hiss and magnetosonic waves.
Brazing Graphite to Aluminum Nitride for Thermal Dissipation Purpose
Authors: Chou Tsung‐Te , Tuan Wei‐Hsing , Nishikawa Hiroshi , Weng Biing‐Jyh
Published: April 2017

In the present study, graphite paper is joined to aluminum nitride (AlN) using an active Ag–Cu–Ti foil. The Ti in the brazing foil diffuses to AlN side to form titanium nitride, to graphite side to form titanium carbide during bonding. The thermal diffusivity of the AlN–AgCuTi graphite joint is double that of AlN substrate; the resulting thermal conductivity of the joint is, thus, higher. Though the flexural strength of the joint is half that of AlN substrate, it can deflect for 1 mm at a 28 mm span without failure. The large deflection capability can be related to the sliding between graphite sheets within the graphite paper
Spatiotemporal Evolution of the Wound Repairing Process in a 3D Human Dermis Equivalent
Authors: Lombardi Bernadette , Casale Costantino , Imparato Giorgia , Urciuolo Francesco , Netti Paolo Antonio
Published: April 2017

Several skin equivalent models have been developed to investigate in vitro the re‐epithelialization process occurring during wound healing. Although these models recapitulate closure dynamics of epithelial cells, they fail to capture how a wounded connective tissue rebuilds its 3D architecture until the evolution in a scar. Here, the in vitro tissue repair dynamics of a connective tissue is replicated by using a 3D human dermis equivalent (3D‐HDE) model composed of fibroblasts embedded in their own extracellular matrix (ECM). After inducing a physical damage, 3D‐HDE undergoes a series of cellular and extracellular events quite similar to those occurring in the native dermis. In particular, fibroblasts differentiation toward myofibroblasts phenotype and neosynthesis of hyaluronic acid, fibronectin, and collagen during the repair process are assessed. Moreover, tissue reorganization after physical damage is investigated by measuring the diameter of bundles and the orientation of fibers of the newly formed ECM network. Finally, the ultimate formation of a scar‐like tissue as physiological consequence of the repair and closure process is demonstrated. Taking together, the results highlight that the presence of cell‐assembled and responsive stromal components enables quantitative and qualitative in vitro evaluation of the processes involved in scarring during wound healing.
Thermoresponsive Emission Switching via Lower Critical Solution Temperature Behavior of Organic–Inorganic Perovskite Nanoparticles
Authors: Nishikubo Ryosuke , Tohnai Norimitsu , Hisaki Ichiro , Saeki Akinori
Published: April 2017

Lead halide perovskites have shown much promise for high‐performing solar cells due to their inherent electronic nature, and though the color of bright‐light emitters based on perovskite nanoparticles can be tuned by halide mixing and/or size control, dynamic switching using external stimuli remains a challenge. This article reports an unprecedented lower critical solution temperature (LCST) for toluene solutions containing methylammonium lead bromide (MAPbBr3), oleic acid, alkylamines, and dimethylformamide. The delicate interplay of these molecules and ions allows for the reversible formation and decomposition of MAPbBr3 nanoparticles upon heating and cooling, which is accompanied by green and blue photoemissions at each state. An intermediate 1D crystal with PbBr2‐amine coordination is found to play pivotal role in this, and a mechanistic insight is provided based on a three‐state model. In addition to a high quantum yield (up to 85%), this system allows for control over the cloud point (30−80 °C) through compositional engineering and the luminescent color (blue to red) via halogen exchange, thus making it a versatile solution for developing functional molecular organic–inorganic LCST quantum dots.
Benzannulation of 2‐Alkenylindoles using Aldehydes by Sequential Triple‐Relay Catalysis: A Route to Carbazoles and Carbazole Alkaloids
Authors: Banerjee Ankush , Sahu Samrat , Maji Modhu Sudan
Published: April 2017

Benzannulation of 2‐alkenylindoles with readily available aldehydes, under one‐pot sequential triple‐relay‐catalysis, provides an easy access to several structurally unique carbazoles including 2‐ and 3‐alkenylcarbazoles. This protecting group‐free method enabled one‐pot synthesis of alkaloids such as hyellazole and 6‐chlorohyellazole, and the formal syntheses of seven other alkaloids. Construction of the core structure, present in murastifoline A, murrafoline E, and related alkaloids was also demonstrated. Even conjugated 3,3′‐biscarbazoles can also be synthesized by one‐pot, two‐fold sequential triple‐relay catalysis.

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Metal Substitution Modulates the Reactivity and Extends the Reaction Scope of Myoglobin Carbene Transfer Catalysts
Authors: Sreenilayam Gopeekrishnan , Moore Eric J. , Steck Viktoria , Fasan Rudi
Published: April 2017

Engineered myoglobins have recently emerged as promising scaffolds for catalyzing carbene‐mediated transformations. In this work, we investigated the effect of altering the metal center and first‐sphere coordination residue on the carbene transfer reactivity of myoglobin. To this end, we first established an efficient protocol for the recombinant expression of myoglobin variants incorporating metalloporphyrins with non‐native metals, including second‐ and third‐row transition metals (ruthenium, rhodium, iridium). Characterization of the cofactor‐substituted myoglobin variants across three different carbene transfer reactions (cyclopropanation, N–H insertion, S–H insertion) revealed a major influence of the nature of the metal center, its oxidation state and first‐sphere coordination environment on the catalytic activity, stereoselectivity, and/or oxygen tolerance of these artificial metalloenzymes. In addition, myoglobin variants incorporating manganese‐ or cobalt‐porphyrins were found capable of catalyzing an intermolecular carbene C–H insertion reaction involving phthalan and ethyl α‐diazoacetate, a reaction not supported by iron‐based myoglobins and previously accessed only using iridium‐based (bio)catalysts. These studies demonstrate how modification of the metalloporphyrin cofactor environment provides a viable and promising strategy to enhance the catalytic properties and extend the reaction scope of myoglobin‐based carbene transfer catalysts.

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Variable clinical course of identical twin neonates with Alström syndrome presenting coincidentally with dilated cardiomyopathy
Authors: Hollander Seth A. , Alsaleh Norah , Ruzhnikov Maura , Jensen Kristen , Rosenthal David N. , Stevenson David A. , Manning Melanie
Published: April 2017

Alström Syndrome (AS) is a rare autosomal recessive disorder caused by mutations in the ALMS1 gene. We report monozygotic twin infants who presented concurrently with symptoms of congestive heart failure (CHF) due to dilated cardiomyopathy (DCM). Following their initial presentation, one twin improved both echocardiographically and functionally while the other twin showed a progressive decline in ventricular function and worsening CHF symptoms requiring multiple hospitalizations and augmentation of heart failure therapy. Concordant findings of nystagmus, vision loss, and developmental delay were noted in both twins. Additional discordant findings included obesity and signs of insulin resistance in one twin. Genetic testing on one sibling confirmed AS. These twins underscore the importance of considering AS in any child presenting with DCM, particularly in infancy, and highlights that, even in monozygotic twins, the clinical course of AS is variable with regard to both the cardiac and non‐cardiac manifestations of the disease.
Familial 18q12.2 deletion supports the role of RNA‐binding protein CELF4 in autism spectrum disorders
Authors: Barone Rita , Fichera Marco , De Grandi Mariaclara , Battaglia Marta , Lo Faro Valeria , Mattina Teresa , Rizzo Renata
Published: April 2017

Deletion of 18q12.2 is an increasingly recognized condition with a distinct neuropsychiatric phenotype. Twenty‐two patients have been described with overlapping neurobehavioral disturbances including developmental delay, intellectual disability of variable degree, seizures, motor coordination disorder, behavioral/emotional disturbances, and autism spectrum disorders. The CUGBP Elav‐like family member 4 (CELF4) gene at 18q12.2 encodes a RNA‐binding protein that links to RNA subsets involved in pre‐ and postsynaptic neurotransmission including almost 30% of potential autism‐related genes. Haploinsufficiency of CELF4 was associated with an autism or autistic behavior diagnosis in two adult patients with de novo 18q12.2 deletions. We report on a girl and her mildly affected mother with a 275 kb deletion at 18q12.2 involving CELF4 and KIAA1328 whose disruption is not associated with any known disease. The child was diagnosed with syndromic intellectual disability and autism at 6 years of age. Her mother had minor dysmorphisms, mild intellectual disability, and autistic behavior. The deleted region reported in this family is one of the smallest so far reported at 18q12.2. This is also the first full clinical description of maternally inherited CELF4 haploinsufficiency. The present study refines the molecular and neuropsychiatric phenotype associated with 18q12.2 deletion leading to CELF4 haploinsufficiency and provides evidence for a role for CELF4 in brain development and autism spectrum disorders.
FMR1 genotype interacts with parenting stress to shape health and functional abilities in older age
Authors: Mailick Marsha , Hong Jinkuk , Greenberg Jan , Dawalt Leann Smith , Baker Mei Wang , Rathouz Paul J.
Published: April 2017

This study investigated the association of genotype (CGG repeats in FMR1) and the health and well‐being of 5,628 aging adults (mean age = 71) in a population‐based study. Two groups were contrasted: aging parents who had adult children with developmental or mental health disabilities (n = 785; the high‐stress parenting group) and aging parents of healthy children who did not have disabilities (n = 4843; the low‐stress parenting group). There were significant curvilinear interaction effects between parenting stress group and CGG repeats for body mass index and indicators of health and functional limitations, and the results were suggestive of interactions for limitations in cognitive functioning. Parents who had adult children with disabilities and whose genotype was two standard deviations above or below the mean numbers of CGGs had poorer health and functional outcomes at age 71 than parents with average numbers of CGGs. In contrast, parents who had healthy adult children and who had similarly high or low numbers of CGG repeats had better health and functional outcomes than parents with average numbers of CGGs. This pattern of gene by environment interactions was consistent with differential susceptibility or the flip‐flop phenomenon. This study illustrates how research that begins with a rare genetic condition (such as fragile X syndrome) can lead to insights about the general population and contributes to understanding of how genetic differences shape the way people respond to environments. © 2017 Wiley Periodicals, Inc.
Orangutan trade, confiscations, and lack of prosecutions in Indonesia
Authors: Nijman Vincent
Published: April 2017

Prosecuting and sentencing law breakers punishes the offender and acts as a deterrent for future law breakers. With thousands of Sumatran and Bornean orangutans (Pongo abelii and P. pygmaeus) having entered private and government rescue centers and facilities, I evaluate the role of successful prosecution in orangutan conservation in Indonesia. Orangutans have been protected in Indonesian since 1931 and they are not allowed to be traded or to be kept as pets. In the period 1993–2016 at least 440 orangutans were formally confiscated, and many more were “donated” to law enforcement agencies. This resulted in seven (7) successful prosecutions by six different courts. Sentencing was lenient (median fine US$ 442 out of a possible US$ 7,600, median prison sentence 8 months out of a possible 5 years) and certainly too low to act as a deterrent. A paradigm shift within government authorities, conservation organizations, the judiciary, and by the general public is needed where trade in orangutans is no longer seen as a crime against an individual animal but as an economic crime that negatively affects society as a whole. Prosecuting offenders for tax evasion, corruption, endangering public health, animal cruelty, and smuggling, in addition to violating protected species laws, would allow for an increase in sentencing, resulting in a stronger deterrent, and greater public support. Conservation and welfare NGOs have a duty to become more proactive in a drive to increase enforcement; rescuing orangutans always has to coincide with prosecuting offenders and failures, and successes of these prosecutions have to be vigorously publicized. Despite numerous commitments made by Indonesia to orangutan conservation, and clear failures to deliver on almost all components, international donors have increased their funding year on year; it is time that this changes to a system where not failure is rewarded but success.
Distinctiveness enhances long‐term event memory in non‐human primates, irrespective of reinforcement
Authors: Lewis Amy , Call Josep , Berntsen Dorthe
Published: April 2017

Non‐human primates are capable of recalling events that occurred as long as 3 years ago, and are able to distinguish between similar events; akin to human memory. In humans, distinctiveness enhances memory for events, however, it is unknown whether the same occurs in non‐human primates. As such, we tested three great ape species on their ability to remember an event that varied in distinctiveness. Across three experiments, apes witnessed a baiting event in which one of three identical containers was baited with food. After a delay of 2 weeks, we tested their memory for the location of the baited container. Apes failed to recall the baited container when the event was undistinctive (Experiment 1), but were successful when it was distinctive (Experiment 2), although performance was equally good in a less‐distinctive condition. A third experiment (Experiment 3) confirmed that distinctiveness, independent of reinforcement, was a consistent predictor of performance. These findings suggest that distinctiveness may enhance memory for events in non‐human primates in the same way as in humans, and provides further evidence of basic similarities between the ways apes and humans remember past events.
Enantioselektive Chemo‐ und Biokatalyse: Partner in der Retrosynthese
Authors: Hönig Moritz , Sondermann Philipp , Turner Nicholas J. , Carreira Erick M.
Published: April 2017

In diesem Aufsatz werden neue Entwicklungen auf den Gebieten der biokatalytischen und chemokatalytischen Synthese diskutiert. Der Beitrag soll als Anleitung für die Verwendung biokatalytischer Methoden in der chemischen Synthese dienen, insbesondere bei retrosynthetischen Überlegungen und Analysen. Die Gliederung dieses Aufsatzes ist nach den Bindungsknüpfungen und ihren jeweiligen synthetischen Methoden strukturiert.
Protein Dimerization on a Phosphonated Calix[6]arene Disc
Authors: Rennie Martin L. , Doolan Aishling M. , Raston Colin L. , Crowley Peter B.
Published: April 2017

Complex formation between cationic cytochrome c and the water‐soluble, poly‐anionic p‐phosphonatocalix[6]arene (pclx6) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx6 that acts like glue to mediate a symmetric (C2) protein dimer. The calixarene disc has a diameter of about 1.5 nm and masks about 360 Å2 of protein surface. The key protein–calixarene contacts occur via two linchpin lysines, with additional contacts provided by a small hydrophobic patch. The protein–calixarene supramolecular assemblies were observed in solution by size‐exclusion chromatography with multi‐angle light scattering and NMR spectroscopy. Using isothermal titration calorimetry and NMR data, an apparent Kd in the low micromolar range was determined for the charge‐rich protein–calixarene complex. In contrast to p‐sulfonatocalix[4]arene, the larger pclx6 has a single, well‐defined binding site that mediates the assembly of cytochrome c in solution.
Grain‐Boundary‐Free Super‐Proton Conduction of a Solution‐Processed Prussian‐Blue Nanoparticle Film
Authors: Ono Kenta , Ishizaki Manabu , Kanaizuka Katsuhiko , Togashi Takanari , Yamada Teppei , Kitagawa Hiroshi , Kurihara Masato
Published: April 2017

A porous crystal family has been explored as alternatives of Nafion films exhibiting super‐proton conductivities of ≥10−2 S cm−1. Here, the proton‐conduction natures of a solution‐processed film of nanoparticles (NPs) have been studied and compared to those of a Nafion film. A mono‐particle film of Prussian‐blue NPs is spontaneously formed on a self‐assembled monolayer substrate by a one‐step solution process. A low‐temperature heating process of the densely packed, pinhole‐free mono‐particle NP film enables a maximum 105‐fold enhancement of proton conductivity, reaching ca. 10−1 S cm−1. The apparent highest conductivity, compared to previously reported data of the porous crystal family, remains constant against humidity changes by an improved water‐retention ability of the film. In our proposed mechanism, the high‐performing solution‐processed NP film suggests that heating leads to the self‐restoration of hydrogen‐bonding networks throughout their innumerable grain boundaries.
Copper‐Catalyzed Aminothiolation of 1,3‐Dienes via a Dihydrothiazine Intermediate
Authors: Sleet Christopher E. , Tambar Uttam K.
Published: April 2017

Heteroatom‐containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3‐dienes is especially attractive. Herein, we describe the development of a regio‐ and diastereoselective 1,4‐aminothiolation of 1,3‐dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol. The reaction proceeds via a tandem hetero‐Diels–Alder cycloaddition of N,N′‐bis(benzenesulfonyl)sulfur diimide with 1,3‐diene followed by copper‐catalyzed Grignard substitution. Mechanistic studies support a copper catalyzed formation of an unprecedented [10‐S‐4] sulfurane that reductively eliminates to afford a 3,6‐dihydrothiazine, which is selectively converted to 1,4‐aminothiols.
Fluorophores for Excited‐State Intramolecular Proton Transfer by an Yttrium Triflate Catalyzed Reaction of Isocyanides with Thiocarboxylic Acids
Authors: Tong Shuo , Zhao Shun , He Qing , Wang Qian , Wang Mei‐Xiang , Zhu Jieping
Published: April 2017

Discovery of new chemical reactivity of a given functional group can often result in innovative synthesis of important chemical entities that possess unprecedented properties. We designed and developed a one‐step synthesis of 5‐amino‐4‐carboxamidothiazoles 1 by an yttrium‐triflate‐catalyzed reaction of thiocarboxylic acids 2 with isocyanides 3. In this reaction, both reactants 2 and 3 deviated from their normal reactivities because of metal coordination. The resulting heterocycles are novel prototypical structures for the double ESIPT process. Some of them were excited by visible light irradiation and emitted fluorescence at the NIR region with large Stokes shift, high quantum yield, and strong solvatochromism.
Cleaving Direct‐Laser‐Written Microstructures on Demand
Authors: Zieger Markus M. , Mueller Patrick , Quick Alexander S. , Wegener Martin , Barner‐Kowollik Christopher
Published: April 2017

Using an advanced functional photoresist we introduce direct‐laser‐written (DLW) 3D microstructures capable of complete degradation on demand. The networks consist exclusively of reversible bonds, formed by irradiation of a phenacyl sulfide linker, giving disulfide bonds in a radical‐free step‐growth polymerization via a reactive thioaldehyde. The bond formation was verified in solution by ESI‐MS. To induce cleavage, dithiothreitol causes a thiol–disulfide exchange, erasing the written structure. The mild cleavage of the disulfide network is highly orthogonal to other, for example, acrylate‐based DLW structures. To emphasize this aspect, DLW structures were prepared incorporating reversible structural elements into a non‐reversible acrylate‐based standard scaffold, confirming subsequent selective cleavage. The high lateral resolution achievable was verified by the preparation of well‐defined line gratings with line separations of down to 300 nm.
Iridium‐Catalyzed Regio‐ and Enantioselective Hydroarylation of Alkenyl Ethers by Olefin Isomerization
Authors: Ebe Yusuke , Onoda Mitsuki , Nishimura Takahiro , Yorimitsu Hideki
Published: April 2017

Iridium‐catalyzed hydroarylation of alkenyl ethers, such as allylic and homoallylic ethers, by C−H bond activation gave high yields of the corresponding addition products, where the aryl groups were selectively installed at the α‐carbon atom to the alkoxy group. The reaction involves an isomerization of the alkenyl ethers into the corresponding 1‐alkenyl ethers, which then undergo the regio‐ and enantioselective hydroarylation.
Relationship between bridged groups and antioxidant activity for aliphatic diamine bridged hindered phenol in polyolefins
Authors: Li Cuiqin , Sun Peng , Guo Suyue , Zhang Zhiqiu , Wang Jun
Published: April 2017

Four aliphatic diamine bridged hindered phenols were successfully synthesized with aliphatic diamine as the bridged group and 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionyl chloride as the material, and their structures were clarified by NMR, Fourier transform infrared spectroscopy, and mass spectrometry. Their performance as antioxidant for polypropylene (PP) and linear low‐density polyethylene (LLDPE) were investigated through the melt flow rate and the oxidation induction time. The thermooxidative stabilities of PP and LLDPE with different aliphatic diamine bridged hindered phenols were assessed by the measurement of the oxidation induction temperature and with long‐term aging testing. The results showed that aliphatic diamine bridged hindered phenols could protect two kinds of polyolefins from thermal oxidative degradation, and the mechanical properties and antioxidant activities of polyolefins stabilized with aliphatic diamine bridged hindered phenols were increased with increasing length of the bridged group for aliphatic diamine bridged hindered phenols at the same concentration of phenolic hydroxyl group. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45095.