bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Diagnostic Cycle Testing of Magnesium and Magnesium Oxide-Pigmented Primers on AA2024-T351
Authors: Santucci R.J. , Kannan B. , Scully J.R. 
Published: August 2017

Intact Mg-rich and MgO-rich primer (MgRP and MgORP) coatings on aluminum alloy 2024-T351 substrate were evaluated for their ability to protect remote scratches (coating defects) as well as for coating barrier properties using a laboratory diagnostic cycle test. These coatings consist of a pretreated substrate and a Mg-containing pigmented primer with and without a UV-inert pigmented topcoat. For MgRP, Mg2+ and electrons are available upon Mg oxidation, while for MgORP only Mg2+ is available upon MgO chemical dissolution. The thickness and the pigment volume concentration of the MgORP was less than the MgRP as characterized with scanning electron microscopy/energy dispersive spectroscopy imaging, resulting in a larger reservoir and Mg capacity in MgRP than the Mg2+ capacity in MgORP. Diagnostic electrochemical cycle testing assessed the anode capacity of Mg pigment available for sacrificial anode-based cathodic protection of the substrate during potentiostatic holds during full-immersion testing in 5 wt% NaCl. The MgO had no capacity for sacrificial anode-based cathodic protection, but it did exhibit beneficial effects associated with the electrochemical behavior of coated and bare AA2024-T351; this was attributed to presence of Mg2+ in solution and the redeposited corrosion product. During exposure, electrochemical impedance spectroscopy monitored the barrier properties of the coatings, which were affected by primer type and the presence of topcoat. MgRP is shown to protect AA2024-T351 via both sacrificial anode-based cathodic protection and Mg2+ redeposition. MgORP is shown to function as a corrosion preventative coating for AA2024-T351 through chemical release of Mg2+, which beneficially alters the electrochemical corrosion behavior of the AA2024-T351 alloy. This investigation serves as a foundation for future investigations into MgORP and spent MgRP in the case where Mg has been oxidized as a result of long-term field exposure.
Observations of VOC emissions and photochemical products over US oil- and gas-producing regions using high-resolution H3O+ CIMS (PTR-ToF-MS)
Authors: Koss Abigail , Yuan Bin , Warneke Carsten , Gilman Jessica B. , Lerner Brian M. , Veres Patrick R. , Peischl Jeff , Eilerman Scott , Wild Rob , Brown Steven S. , Thompson Chelsea R. , Ryerson Thomas , Hanisco Thomas , Wolfe Glenn M. , Clair Jason M. St. , Thayer Mitchell , Keutsch Frank N. , Murphy Shane , de Gouw Joost 
Published: August 2017

Abstract. VOCs related to oil and gas extraction operations in the United States were measured by H3O+ chemical ionization time-of-flight mass spectrometry (H3O+ ToF-CIMS/PTR-ToF-MS) from aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign in March–April 2015. This work presents an overview of major VOC species measured in nine oil- and gas-producing regions, and a more detailed analysis of H3O+ ToF-CIMS measurements in the Permian Basin within Texas and New Mexico. Mass spectra are dominated by small photochemically produced oxygenates and compounds typically found in crude oil: aromatics, cyclic alkanes, and alkanes. Mixing ratios of aromatics were frequently as high as those measured downwind of large urban areas. In the Permian, the H3O+ ToF-CIMS measured a number of underexplored or previously unreported species, including aromatic and cycloalkane oxidation products, nitrogen heterocycles including pyrrole (C4H5N) and pyrroline (C4H7N), H2S, and a diamondoid (adamantane) or unusual monoterpene. We additionally assess the specificity of a number of ion masses resulting from H3O+ ion chemistry previously reported in the literature, including several new or alternate interpretations.
Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin
Authors: Aloysius Noel , Saiers James 
Published: August 2017

Abstract. Despite their global significance, the impacts of climate change on water resources and associated ecosystem services in the Congo River basin (CRB) have been understudied. Of particular need for decision makers is the availability of spatial and temporal variability of runoff projections. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs) under two greenhouse gas emission scenarios, we explore the variability in modeled runoff in the near future (2016–2035) and mid-century (2046–2065). We find that total runoff from the CRB is projected to increase by 5 % [−9 %; 20 %] (mean – min and max – across model ensembles) over the next two decades and by 7 % [−12 %; 24 %] by mid-century. Projected changes in runoff from subwatersheds distributed within the CRB vary in magnitude and sign. Over the equatorial region and in parts of northern and southwestern CRB, most models project an overall increase in precipitation and, subsequently, runoff. A simulated decrease in precipitation leads to a decline in runoff from headwater regions located in the northeastern and southeastern CRB. Climate model selection plays an important role in future projections for both magnitude and direction of change. The multimodel ensemble approach reveals that precipitation and runoff changes under business-as-usual and avoided greenhouse gas emission scenarios (RCP8.5 vs. RCP4.5) are relatively similar in the near term but deviate in the midterm, which underscores the need for rapid action on climate change adaptation. Our assessment demonstrates the need to include uncertainties in climate model and emission scenario selection during decision-making processes related to climate change mitigation and adaptation.
Evaluating the roll-out of environmental control units in Veterans Affairs Spinal Cord Injury Centers: Workflow observations
Authors: Bidassie Balmatee , Vallette Marissa A. , James Theadora , Martinez Rachael , Etingen Bella , Cozart Huberta , Weaver Frances M 
Published: August 2017

Objective: Evaluate the value of providing environmental control units (ECUs) to Veterans with spinal cord injuries and/or disorders (SCI/D) in Veterans Affairs Medical Centers (VAMCs).Design: Industrial engineers observed SCI/D staff (support) and Veterans (use) with ECUs at four participating VAMC Spinal Cord Injury (SCI) Centers.Measure(s)/Analysis: Standardized data collection efforts included: 1) time study (trend analysis) and 2) open-ended, semistructured interviews on Strengths-Weaknesses-Opportunities-Threats (SWOT) feedback (qualitative analysis).Results: From 59 interactions, reasons for ECU downtime were troubleshooting (n = 30, 51%), repairs/replacements (n = 10, 17%), and 29% combined for patient education (n = 8), set-up (n = 5), and admission (n = 4). ECU strengths were functionality (n = 23, 70%) and 30% (n = 10) combined for patient independence and staff satisfaction. Functionality was both a weakness (n = 43, 78%) and opportunity (n = 29, 66%). Threats were functionality (n = 8, 50%), staff satisfaction (n = 3, 19%), and maintenance (n = 5, 31%). When ECUs were functioning properly, Veterans participated in leisurely activities (e.g., games, television), had increased control of their environment (e.g., bed, lights), and clinicians spent less time troubleshooting the ECU, hence, increasing clinical care availability.Conclusions: ECUs minimized physical limitation challenges, and may improve safety, comfort level, and general satisfaction with care of Veterans with SCI/D who often spend much of their time in bed when hospitalized. Veterans and staff reported that the ECUs added value by increasing patient independence and social support including communication with loved ones. Functionality strengths and weaknesses influenced the Veterans’/staff’s perceptions of ECU value. Therefore, ECU training/maintenance education and dedicated non-clinical support staff are recommended prior to future ECU roll-out.
De relatie tussen islam en terrorisme
Authors: Croes M.T. 
Published: August 2017

Islamic terrorism, Islamic terrorists? An empirical approach
In this contribution the author focuses on the relationship between Islam and terrorism. Based on data from the Global Terrorism Database he argues that Islamic terrorism dominates worldwide since 2002. Paying attention to the creed of the jihadists, Salafism, he argues that it is a continuation of the puritanical tradition within Sunni Islam.
Repères de stagiaires finissants en enseignement permettant de soutenir le développement de leur compétence éthique
Authors: Cloutier Guylaine , St-Vincent Lise-Anne 
Published: August 2017

Devant les exigences liées à la professionnalisation enseignante et, par conséquent, devant les attentes à l’égard de la compétence éthique des enseignants, il convient d’abord de se pencher sur ce que signifie être compétent sur le plan éthique. Il ressort des écrits que la compétence éthique entretient un lien étroit avec la réflexion. Il importe ensuite de s’interroger en ce sens sur l’apport de la formation au développement de cette compétence professionnelle.
Cet article présente une partie des résultats issus d’une recherche doctorale portant sur l’agir éthique de stagiaires finissants en enseignement au secondaire. Plus précisément, ces résultats jettent un regard sur ce qui constitue le raisonnement professionnel des stagiaires lié à une situation comportant des enjeux éthiques. Des repères qui soutiennent l’argumentaire des participants stagiaires sont mis en évidence, bien que les mots pour les désigner explicitement soient peu présents dans le discours de ces participants. Les stagiaires expriment le fait qu’ils ne se sentent pas suffisamment outillés en matière d’éthique professionnelle. Entre autres, selon leur point de vue, l’éthique telle qu’elle est abordée lors des activités d’enseignement en formation, particulièrement à l’aide de problématisations éthiques, comporterait un caractère « insoluble ».
Microbiome succession during ammonification in eelgrass bed sediments
Authors: Ettinger Cassandra L. , Williams Susan L. , Abbott Jessica M. , Stachowicz John J. , Eisen Jonathan A. 
Published: August 2017

BackgroundEelgrass (Zostera marina) is a marine angiosperm and foundation species that plays an important ecological role in primary production, food web support, and elemental cycling in coastal ecosystems. As with other plants, the microbial communities living in, on, and near eelgrass are thought to be intimately connected to the ecology and biology of eelgrass. Here we characterized the microbial communities in eelgrass sediments throughout an experiment to quantify the rate of ammonification, the first step in early remineralization of organic matter, also known as diagenesis, from plots at a field site in Bodega Bay, CA.MethodsSediment was collected from 72 plots from a 15 month long field experiment in which eelgrass genotypic richness and relatedness were manipulated. In the laboratory, we placed sediment samples (n = 4 per plot) under a N2atmosphere, incubated them atin situtemperatures (15 °C) and sampled them initially and after 4, 7, 13, and 19 days to determine the ammonification rate. Comparative microbiome analysis using high throughput sequencing of 16S rRNA genes was performed on sediment samples taken initially and at seven, 13 and 19 days to characterize changes in the relative abundances of microbial taxa throughout ammonification.ResultsWithin-sample diversity of the sediment microbial communities across all plots decreased after the initial timepoint using both richness based (observed number of OTUs, Chao1) and richness and evenness based diversity metrics (Shannon, Inverse Simpson). Additionally, microbial community composition changed across the different timepoints. Many of the observed changes in relative abundance of taxonomic groups between timepoints appeared driven by sulfur cycling with observed decreases in predicted sulfur reducers (Desulfobacterales) and corresponding increases in predicted sulfide oxidizers (Thiotrichales). None of these changes in composition or richness were associated with variation in ammonification rates.DiscussionOur results showed that the microbiome of sediment from different plots followed similar successional patterns, which we infer to be due to changes related to sulfur metabolism. These large changes likely overwhelmed any potential changes in sediment microbiome related to ammonification rate. We found no relationship between eelgrass presence or genetic composition and the microbiome. This was likely due to our sampling of bulk sediments to measure ammonification rates rather than sampling microbes in sediment directly in contact with the plants and suggests that eelgrass influence on the sediment microbiome may be limited in spatial extent. More in-depth functional studies associated with eelgrass microbiome will be required in order to fully understand the implications of these microbial communities in broader host-plant and ecosystem functions (e.g., elemental cycling and eelgrass-microbe interactions).
Growth of the purple snail Plicopurpura pansa in Baja California Sur, Mexico
Authors: Ramírez-Rodríguez M , Naegel LCA 
Published: August 2017

To study the growth of the purple snail Plicopurpura pansa at the northern limit of its distribution, from 1999 to 2001 monthly random samples were obtained from two beaches in the southern part of the Baja California Peninsula (Mexico): one on the Gulf of California and the other on the west coast of the peninsula. Mark and recapture experiments, as well as laboratory rearing were also done. The von Bertalanffy growth equation parameters derived from length frequency data were K = 0.17 and L∞ = 90 mm, and agree with those estimated from the mark and recapture data, but are lower that those reported in the literature for P. pansa from the central and southern Mexican Pacific. Snails maintained under laboratory conditions had low growth rates. These results could be used to implement models for the assessment of purple snail fisheries.
Three‐dimensional lithospheric S wave velocity model of the NE Tibetan Plateau and western North China Craton
Authors: Wang Xingchen , Li Yonghua , Ding Zhifeng , Zhu Lupei , Wang Chunyong , Bao Xuewei , Wu Yan 
Published: August 2017

AbstractWe present a new 3‐D lithospheric Vs model for the NE Tibetan Plateau (NETP) and the western North China Craton (NCC). First, high‐frequency receiver functions (RFs) were inverted using the neighborhood algorithm to estimate the sedimentary structure beneath each station. Then a 3D Vs model with unprecedented resolution was constructed by jointly inverting RFs and Rayleigh wave dispersions. A low‐velocity sedimentary layer with thicknesses varying from 2 to 10 km is present in the Yinchuan‐Hetao graben, Ordos block, and western Alxa block. Velocities from the middle‐lower crust to the uppermost mantle are generally high in the Ordos block and low in the Alxa block, indicating that the Alxa block is not part of the NCC. The thickened crust in southwestern Ordos block and western Alxa block suggests that they have been modified. Two crustal low‐velocity zones (LVZs) were detected beneath the Kunlun Fault (KF) zone and western Qilian Terrane (QLT). The origin of the LVZ beneath the KF zone may be the combined effect of shear heating, localized asthenosphere upwelling, and crustal radioactivity. The LVZ in the western QLT, representing an early stage of the LVZ that has developed in the KF zone, acts as a decollement to decouple the deformation between the upper and lower crust and plays a key role in seismogenesis. We propose that the crustal deformation beneath the NETP is accommodated by a combination of shear motion, thickening of the upper‐middle crust, and removal of lower crust.
Influence of pyroxene and spinel on the kinetics of peridotite serpentinization
Authors: Huang Ruifang , Song Maoshuang , Ding Xing , Zhu Sanyuan , Zhan Wenhuan , Sun Weidong 
Published: August 2017

AbstractHydrothermal experiments were performed at 311°C and 3.0 kbar on natural olivine and peridotite to investigate the kinetics of serpentinization. The results show that the rates of reaction strongly depend on grain sizes of solid reactants, with smaller grain sizes resulting in faster kinetics. After 27 days of reaction, the reaction extent was 99% for peridotite with grain sizes of <30 μm, and the reaction extent was 28% for grain sizes of 100–177 μm. Compared to peridotite, olivine is serpentinized at much slower rates, e.g., 5.3% of reaction extent was achieved for olivine with grain sizes of 100–177 μm after 27 days, approximately five times lower than that reached during peridotite serpentinization. Such contrasting results are due to the presence of pyroxene and spinel, an interpretation which is supported by a marked increase in reaction extents for experiments with the addition of pyroxene and spinel. The reaction extent achieved in experiments with 3 wt % spinel greatly increased to 98% after 27 days, much higher than that achieved during olivine serpentinization. These results appear to be related to pyroxene and spinel releasing Al and Cr during serpentinization. As indicated by compositions of serpentine, orthopyroxene lost ~60% of Al at a reaction extent of 59%. Influence of Al and Cr is suggested by a dramatic increase in reaction extents with the addition of Al2O3 and Cr2O3 powders. Olivine in natural geological settings is commonly associated with pyroxene and spinel; consequently, serpentinization kinetics may be much faster than previously thought.
Seismic velocity changes concentrated at the shallow structure as inferred from correlation analyses of ambient noise during volcano deformation at Izu‐Oshima, Japan
Authors: Takano Tomoya , Nishimura Takeshi , Nakahara Hisashi 
Published: August 2017

AbstractWe investigate the stress sensitivity of velocity changes at Izu‐Oshima in Japan using seismic interferometry method. We calculate cross correlation functions (CCFs) of ambient noises recorded by four seismic stations on the active volcano from 1 January 2012 to 31 December 2015 at 0.5–1 Hz, 1–2 Hz, and 2–4 Hz. Applying moving time windows to calculate cross spectrum between daily CCFs and reference CCF, which is the average for the all observation period, we compute daily velocity changes. The obtained velocity changes vary from −1% to 3% with a dominant period of about 1 year. We calculate areal strains by using Global Navigation Satellite Systems data at the volcano. It is evident that the velocity changes are well correlated with the areal strain changes whose linear trend is removed. The stress sensitivity of velocity changes, which are obtained from the observed velocity changes and areal strains, is lower at 0.5–1 Hz than that at higher frequencies: (7.1 ± 1.3) × 10−8 Pa−1 at 0.5–1 Hz, (1.4 ± 0.1) × 10−7 Pa−1 at 1–2 Hz, and (1.3 ± 0.1) × 10−7 Pa−1 at 2–4 Hz. Modeling the velocity changes of Rayleigh wave propagating in layered structures, we find that the observed velocity changes are concentrated in the upper 1 km of the structure. Since similar frequency dependency is recognized among the stress sensitivity of velocity changes reported in previous studies, we conclude that the velocity changes are localized in the shallow depth because of the increase of confining pressure.
Nonlinear softening of unconsolidated granular earth materials
Authors: Lieou Charles K. C. , Daub Eric G. , Guyer Robert A. , Johnson Paul A. 
Published: August 2017

AbstractUnconsolidated granular earth materials exhibit softening behavior due to external perturbations such as seismic waves, namely, the wave speed and elastic modulus decrease upon increasing the strain amplitude above dynamics strains of about 10−6 under near‐surface conditions. In this letter, we describe a theoretical model for such behavior. The model is based on the idea that shear transformation zones—clusters of grains that are loose and susceptible to contact changes, particle displacement, and rearrangement—are responsible for plastic deformation and softening of the material. We apply the theory to experiments on simulated fault gouge composed of glass beads and demonstrate that the theory predicts nonlinear resonance shifts, reduction of the P wave modulus, and attenuation, in agreement with experiments. The theory thus offers insights on the nature of nonlinear elastic properties of a granular medium and potentially into phenomena such as triggering on earthquake faults.
Uplift, rupture, and rollback of the Farallon slab reflected in volcanic perturbations along the Yellowstone adakite hot spot track
Authors: Camp Victor E. , Ross Martin E. , Duncan Robert A. , Kimbrough David L. 
Published: August 2017

AbstractField, geochemical, and geochronological data show that the southern segment of the ancestral Cascades arc advanced into the Oregon back‐arc region from 30 to 20 Ma. We attribute this event to thermal uplift of the Farallon slab by the Yellowstone mantle plume, with heat diffusion, decompression, and the release of volatiles promoting high‐K calc‐alkaline volcanism throughout the back‐arc region. The greatest degree of heating is expressed at the surface by a broad ENE‐trending zone of adakites and related rocks generated by melting of oceanic crust from the Farallon slab. A hiatus in eruptive activity began at ca. 22–20 Ma but ended abruptly at 16.7 Ma with renewed volcanism from slab rupture occurring in two separate regions. The eastern rupture resulted in the extrusion of Steens Basalt during the ascent and melting of a dry mantle (plume) source contaminated with depleted mantle. The contemporaneous western rupture resulted in renewed subduction, melting of a wet mantle source, and the rejuvenation of high‐K calc‐alkaline volcanism near the Nevada‐California border at 16.7 Ma. Here the initiation of slab rollback is evident in the westward migration of arc volcanism at 7.8 km/Ma. Today, the uplifted slab is largely missing beneath the Oregon back‐arc region, replaced instead by a seismic hole that is bound on the south by the adakite hot spot track. We attribute slab destruction to thermal uplift and mechanical dislocation that culminated in rapid tearing of the slab from 17–15 Ma and possible foundering and sinking of slab segments from 16 to 10 Ma.
Plant species, not climate, controls aboveground biomass O2:CO2 exchange ratios in deciduous and coniferous ecosystems
Authors: Gallagher Morgan E. , Liljestrand Frasier L. , Hockaday William C. , Masiello Caroline A. 
Published: August 2017

AbstractThe oxidative ratio (OR) is the O2:CO2 ratio associated with photosynthesis, respiration, and other ecosystem gas exchange processes and can be reported on the scale of an individual leaf, an ecosystem, up to the entire terrestrial biosphere. The OR of the terrestrial biosphere is used to partition anthropogenic CO2 between oceanic and terrestrial carbon sinks, and the ease of measurement of this property on smaller scales suggests its potential for other uses. However, controls on the natural variation of OR are not understood in either organic matter pools or fluxes, and this lack of basic information limits the use of the tracer. Here we assess the annual variability of the OR of photosynthesis over ~decade for two temperate forests, one coniferous and one deciduous, and show that the photosynthetic OR signature is strongly dominated by plant species. We determined the OR of this flux by measuring the OR of carbon pools that close on annual or shorter timescales (leaves and individual tree rings), via solid‐state 13C NMR spectroscopy and elemental analysis. Leaf litter OR is different between coniferous and deciduous forests, but tree bole OR is constant between species. There was no significant change in leaf litter OR with time, nor any correlations between leaf litter OR and temperature or precipitation. During this time growing season precipitation varied by 95% from the time period average, and growing season temperature by 22%, demonstrating that on the decadal scale photosynthetic OR is invariant over significant shifts in these climate parameters.