bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability and localization of rapid shear in fluid‐saturated fault gouge: 2. Localized zone width and strength evolution
Authors: Platt John D. , Rudnicki John W. , Rice James R. 
Published: April 2014

AbstractField and laboratory observations indicate that at seismic slip rates most shearing is confined to a very narrow zone, just a few tens to hundreds of microns wide, and sometimes as small as a few microns. Rice et al. (2014) analyzed the stability of uniform shear in a fluid‐saturated gouge material. They considered two distinct mechanisms to limit localization to a finite thickness zone, rate‐strengthening friction, and dilatancy. In this paper we use numerical simulations to extend beyond the linearized perturbation context in Rice et al. (2014), and study the behavior after the loss of stability. Neglecting dilatancy we find that straining localizes to a width that is almost independent of the gouge layer width, suggesting that the localized zone width is set by the physical properties of the gouge material. Choosing parameters thought to be representative of a crustal depth of 7 km, this predicts that deformation should be confined to a zone between 4 and 44 μm wide. Next, considering dilatancy alone we again find a localized zone thickness that is independent of gouge layer thickness. For dilatancy alone we predict localized zone thicknesses between 1 and 2 μm wide for a depth of 7 km. Finally, we study the impact of localization on the shear strength and temperature evolution of the gouge material. Strain rate localization focuses frictional heating into a narrower zone, leading to a much faster temperature rise than that predicted when localization is not accounted for. Since the dynamic weakening mechanism considered here is thermally driven, this leads to accelerated dynamic weakening.
Diurnal cycle of fossil and nonfossil carbon using radiocarbon analyses during CalNex
Authors: Zotter Peter , El‐Haddad Imad , Zhang Yanlin , Hayes Patrick L. , Zhang Xiaolu , Lin Ying‐Hsuan , Wacker Lukas , Schnelle‐Kreis Jürgen , Abbaszade Gülcin , Zimmermann Ralf , Surratt Jason D. , Weber Rodney , Jimenez José L. , Szidat Sönke , Baltensperger Urs , Prévôt André S. H. 
Published: April 2014

AbstractRadiocarbon (14C) analysis is a unique tool to distinguish fossil/nonfossil sources of carbonaceous aerosols. We present 14C measurements of organic carbon (OC) and total carbon (TC) on highly time resolved filters (3–4 h, typically 12 h or longer have been reported) from 7 days collected during California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 in Pasadena. Average nonfossil contributions of 58% ± 15% and 51% ± 15% were found for OC and TC, respectively. Results indicate that nonfossil carbon is a major constituent of the background aerosol, evidenced by its nearly constant concentration (2–3 μgC m−3). Cooking is estimated to contribute at least 25% to nonfossil OC, underlining the importance of urban nonfossil OC sources. In contrast, fossil OC concentrations have prominent and consistent diurnal profiles, with significant afternoon enhancements (~3 μgC m−3), following the arrival of the western Los Angeles (LA) basin plume with the sea breeze. A corresponding increase in semivolatile oxygenated OC and organic vehicular emission markers and their photochemical reaction products occurs. This suggests that the increasing OC is mostly from fresh anthropogenic secondary OC (SOC) from mainly fossil precursors formed in the western LA basin plume. We note that in several European cities where the diesel passenger car fraction is higher, SOC is 20% less fossil, despite 2–3 times higher elemental carbon concentrations, suggesting that SOC formation from gasoline emissions most likely dominates over diesel in the LA basin. This would have significant implications for our understanding of the on‐road vehicle contribution to ambient aerosols and merits further study.
Runoff‐mediated seasonal oscillation in the dynamics of dissolved organic matter in different branches of a large bifurcated estuary—The Changjiang Estuary
Authors: Guo Weidong , Yang Liyang , Zhai Weidong , Chen Wenzhao , Osburn Christopher L. , Huang Xiao , Li Yan 
Published: April 2014

AbstractThe Changjiang Estuary is a large bifurcated estuary where different hydrodynamic processes influence its South Branch compared to its North Branch. The South Branch is the dominant pathway of Changjiang River discharge, while the shallower and narrower North Branch is dominated by salt water intrusion, especially in the dry season. Absorption and fluorescence spectroscopy were measured along with dissolved organic carbon (DOC) concentrations to characterize the properties of dissolved organic matter (DOM) collected in different seasons during an extreme drought year in 2011. The refractory DOM from the Changjiang River flowed mainly through the South Branch, whereas in the lower South Branch, the input from the polluted Huangpu River contributed a large amount of biolabile DOM, demonstrating an anthropogenic perturbation from megacities. The DOM properties in the North Branch showed conservative behavior in the wet season, while noticeable addition was observed in the dry season, accompanied by the reversed flux of DOM from the North Branch to the South Branch, emphasizing the regular seasonal oscillation of the DOM dynamics in this monsoon‐controlled bifurcated estuary. The estuarine turbidity maximum zones played distinct roles on DOM dynamics in different estuarine environments. The DOC and chromophoric DOM (CDOM) abundance in the Changjiang River and other Chinese rivers were at lower levels compared to other world rivers, showing a characteristic of the regional CDOM‐poor features for many East Asia rivers.
Evidence for a nonmonotonic relationship between ecosystem‐scale peatland methane emissions and water table depth
Authors: Brown Mathew G. , Humphreys Elyn R. , Moore Tim R. , Roulet Nigel T. , Lafleur Peter M. 
Published: April 2014

AbstractAlthough temporal and spatial variations in peatland methane (CH4) emissions at broad scales are often related to water table (WT) using a linear relationship, a potentially complex relationship exists between these variables locally and over shorter time scales. To explore this issue, CH4 fluxes were measured using eddy covariance at the Mer Bleue bog over two summer seasons. Peak CH4 emissions (30 to 50 mg CH4‐C m−2 d−1) occurred not when the WT was closest to the surface but instead, when it dropped to 40 to 55 cm below the surface. When the WT was below or above this zone, average fluxes were ~14 mg CH4‐C m−2 d−1. We speculate this critical zone coincides with the necessary redox potentials and sources of fresh organic material that lead to maximum production of CH4 and/or with conditions that lead to degassing of stored CH4. However, as expected, total summer CH4 emissions were 47% lower during the drier year. This occurred in part because the WT was within the critical zone for fewer days in the drier year but also because after an extended midsummer dry period there was little recovery of CH4 emissions, even a month after rewetting.
Emergent constraints on climate‐carbon cycle feedbacks in the CMIP5 Earth system models
Authors: Wenzel Sabrina , Cox Peter M. , Eyring Veronika , Friedlingstein Pierre 
Published: April 2014

AbstractAn emergent linear relationship between the long‐term sensitivity of tropical land carbon storage to climate warming (γLT) and the short‐term sensitivity of atmospheric carbon dioxide (CO2) to interannual temperature variability (γIAV) has previously been identified by Cox et al. (2013) across an ensemble of Earth system models (ESMs) participating in the Coupled Climate‐Carbon Cycle Model Intercomparison Project (C4MIP). Here we examine whether such a constraint also holds for a new set of eight ESMs participating in Phase 5 of the Coupled Model Intercomparison Project. A wide spread in tropical land carbon storage is found for the quadrupling of atmospheric CO2, which is of the order of 252 ± 112 GtC when carbon‐climate feedbacks are enabled. Correspondingly, the spread in γLT is wide (−49 ± 40 GtC/K) and thus remains one of the key uncertainties in climate projections. A tight correlation is found between the long‐term sensitivity of tropical land carbon and the short‐term sensitivity of atmospheric CO2 (γLT versus γIAV), which enables the projections to be constrained with observations. The observed short‐term sensitivity of CO2 (−4.4 ± 0.9 GtC/yr/K) sharpens the range of γLT to −44 ± 14 GtC/K, which overlaps with the probability density function derived from the C4MIP models (−53 ± 17 GtC/K) by Cox et al. (2013), even though the lines relating γLT and γIAV differ in the two cases. Emergent constraints of this type provide a means to focus ESM evaluation against observations on the metrics most relevant to projections of future climate change.
Geochemical insights into the internal dynamics of debris avalanches. A case study: The Socompa avalanche, Chile
Authors: Doucelance Régis , Kelfoun Karim , Labazuy Philippe , Bosq Chantal 
Published: April 2014

AbstractOne way to infer the internal dynamics of debris avalanches is to characterize the heterogeneity of their deposits. Here we present high‐precision Sr‐Nd isotope compositions, plus major and trace element concentrations, of matrix samples and rock fragments from the Socompa debris‐avalanche deposit (Chile). The Socompa blocks are easily identifiable in the field, but distinguishing substrate debris from disaggregated material formed at the volcano is difficult to do with only field criteria. Combining isotope data with field observations can help with this. Measured Sr and Nd isotope ratios show significant variations, defining a binary mixing array where matrix and rock deposits overlap. This testifies to the mixing of crushed rocks during collapse and/or movement. Assimilation of Socompa basement appears to be variable; overall, it is far lower than was previously proposed. Comparison between matrix and block samples in contact, over the whole surface area of the deposit, shows that the isotopic heterogeneity increases from source to front. Close to the Socompa, matrices are resulting from simple crushing of adjacent rocks. At the front, rock samples with distinct compositions are found in a close relationship with matrices that result either from mixing of these (or some of these) rocks or from crushing of basement material. Between the source and the front, the efficient mixing of Socompa rocks (and basement rocks) generates matrices with isotopic compositions distinct from those of the blocks they are in contact with. We interpret these results as being due to more efficient vertical mixing during the avalanche emplacement.
Contrasting subduction structures within the Philippine Sea plate: Hydrous oceanic crust and anhydrous volcanic arc crust
Authors: Arai Ryuta , Iwasaki Takaya , Sato Hiroshi , Abe Susumu , Hirata Naoshi 
Published: April 2014

AbstractWe show contrasting subduction structures within the Philippine Sea plate inferred from active‐source wide‐angle reflection data. Previous studies showed that large‐amplitude reflections from the slab are observed in southwest Japan and indicated that a thin low‐velocity layer with a high fluid content is formed along the top of the subducting oceanic crust. On the contrary, we found that the slab reflections have smaller amplitudes in the Izu collision zone, central Japan, where the Izu‐Bonin volcanic arc has been colliding/subducting, suggesting that such a low‐velocity layer does not exist beneath the collision zone. This structural difference is also supported by P‐wave and S‐wave velocity anomalies by passive‐source tomography and electrical conductivity, and correlates with the regional distribution of deep tremors and intraslab earthquakes, both of which are induced by dehydration processes within the downgoing slab. Based on these comparisons, we suggest that the original structure of the incoming plate controls the contrasting subducting systems: typical oceanic plate absorbs water by hydrothermal circulation at spreading centers and/or seawater infiltration at outer rises, whereas volcanic arc crust consumes a large amount of hydrous minerals for melt production and metamorphoses to more stable, anhydrous forms before subduction.
Sites for Methane Activation on Lithium‐Doped Magnesium Oxide Surfaces
Authors: Kwapien Karolina , Paier Joachim , Sauer Joachim , Geske Michael , Zavyalova Ulyana , Horn Raimund , Schwach Pierre , Trunschke Annette , Schlögl Robert 
Published: April 2014

AbstractDensity functional calculations yield energy barriers for H abstraction by oxygen radical sites in Li‐doped MgO that are much smaller (12±6 kJ mol−1) than the barriers inferred from different experimental studies (80–160 kJ mol−1). This raises further doubts that the Li+O.− site is the active site as postulated by Lunsford. From temperature‐programmed oxidative coupling reactions of methane (OCM), we conclude that the same sites are responsible for the activation of CH4 on both Li‐doped MgO and pure MgO catalysts. For a MgO catalyst prepared by sol–gel synthesis, the activity proved to be very different in the initial phase of the OCM reaction and in the steady state. This was accompanied by substantial morphological changes and restructuring of the terminations as transmission electron microscopy revealed. Further calculations on cluster models showed that CH4 binds heterolytically on Mg2+O2− sites at steps and corners, and that the homolytic release of methyl radicals into the gas phase will happen only in the presence of O2.
“True” biocomposites with biopolyesters and date seed powder: Mechanical, thermal, and degradation properties
Authors: Mittal Vikas , Chaudhry A. U. , Matsko Nadejda B. 
Published: April 2014

ABSTRACTBiopolymers have gained research focus due to enhanced property profiles as well as need to replace the fossil fuel based polymeric materials. The generation of biocomposites with functional biofillers can lead to further enhancement of their potential. In this study, composites of date seed powder with biopolyesters poly(butylene adipate‐co‐terephthalate) (PBAT) and poly‐l‐lactide (PLA) have been demonstrated. The composites exhibited individual degradation peaks for the components in the thermogravimetric analysis (TGA), but still had suitable thermal performance confirmed by the dynamic TGA. The filler also modified the crystalline morphology of the polymers differently. The tensile modulus of the PBAT‐based composites had enhancement of more than 300% in the composite with 40% filler content. The PLA composites also enhanced the modulus marginally till 20% filler content, however, it was still significant due to the very high modulus of PLA as compared to PBAT. The rheological properties indicated the polymer still had viscous behavior even when high amount of filler was added. The storage and loss modulus of the composites enhanced with filler fraction, the PLA composites with 30 and 40% content, however, exhibited very high values probably due to filler aggregates and low filler‐polymer interfacial interactions. The filler particles were observed to be uniformly distributed in the polymer matrices, though some filler aggregates were also observed in the composites with higher filler fractions. After embedding in compost soil, the composites had significantly enhanced extent of biodegradation as compared to pure polymers, thus, confirming the “true” biocomposite nature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40816.
New Conjugated Molecules with Two and Three Dithienyldiketopyrrolopyrrole (DPP) Moieties Substituted at meta Positions of Benzene toward p‐ and n‐Type Organic Photovoltaic Materials
Authors: Yu Chenmin , He Chang , Yang Yang , Cai Zhengxu , Luo Hewei , Li Wenqiang , Peng Qian , Zhang Guanxin , Liu Zitong , Zhang Deqing 
Published: April 2014

AbstractTwo conjugated molecules, TADPP3 and TADPP2‐TT, are reported, in which three and two dithienyldiketopyrrolopyrrole (DPP) moieties, respectively, are substituted at the meta positions of benzene. Based on cyclic voltammetry and absorption data, TADPP3 and TADPP2‐TT possess similar HOMO and LUMO energies of about −5.2 and −3.4 eV, respectively. Thin films of TADPP3 and TADPP2‐TT exhibit p‐type semiconducting behavior with hole mobilities of 2.36×10−3 and 3.76×10−4 cm2 V−1 s−1 after thermal annealing. Molecules TADPP3 and TADPP2‐TT were utilized as p‐type photovoltaic materials to fabricate organic solar cells after blending with phenyl C71 butyric acid methyl ester (PC71BM) and phenyl C61 butyric acid methyl ester (PC61BM). The relatively low JSC and fill factor values can be attributed to poor film morphologies based on AFM and XRD studies. A solar cell with a thin film of TADPP3 with PC71BM in a weight ratio of 1:2 exhibits a high open‐circuit voltage (VOC) of 0.99 V and a power conversion efficiency (PCE) of 2.47 %. Interestingly, TADPP3 can also be employed as an n‐type photovoltaic material. The blended thin film of TADPP3 with P3HT in a weight ratio of 1:2 gave a high VOC of 1.11 V and a PCE of 1.08 % after thermal annealing.
Vision‐Based Trajectory Tracking System for an Emulated Quadrotor UAV
Authors: Jurado Francisco , Palacios Guillermo , Flores Francisco , Becerra Héctor M. 
Published: April 2014

AbstractIn this paper, a vision‐based system is proposed, using the KINECT sensor (KS), for three‐dimensional (3D) trajectory tracking. A target object to track in the 3D space is defined in order to describe its trajectory on a virtual reality environment by an emulated quadrotor unmanned aerial vehicle (UAV). The 3D position vector for the centroid of the target to track is recovered from image processing and information from the depth camera. A color‐based object tracking approach is used. A stable fuzzy controller, as well as a LQR controller, for the emulated quadrotor UAV are implemented and compared, where the estimated 3D position of the target is given as reference signal. Important benefits of the proposed object tracking method are its efficiency in the use of the information provided by the KS with a low computational cost for image processing to estimate the target object position and the possibility of improving robustness of the image segmentation by online adjustment of the color filtering parameters. The main contribution of the paper is the use of the estimated position as the reference for the simultaneous control of attitude and translation of a quadrotor from a single controller. Experimental simulation results validate the proposed approach.
Methodology for biorefinery portfolio assessment using supply‐chain fundamentals of bioproducts
Authors: Dansereau Louis Patrick , El‐Halwagi Mahmoud , Chambost Virginie , Stuart Paul 
Published: April 2014

AbstractGiven the emergence of innovative processes in recent years for the manufacture of bioproducts from second‐generation biomass, a range of unique biorefinery strategies are likely to be implemented by forest product companies in the coming years. No matter what biorefinery strategy is employed, to compete in the longer term, it will be critical to have a supply‐chain adapted to the targeted products. In order to meet customer needs and at the same time be cost‐competitive, there are trade‐offs to be made between responsiveness and efficiency in several areas of the supply chain, such as production and customer service. This paper reviews supply‐chain characteristics and competitive factors for various bioproducts. An approach that can be used by decision‐makers during early‐stage design is presented, suitable for screening‐out less promising options based on their supply‐chain characteristics. Fundamental aspects such as the differentiation of products, their possible green advantage, biomass procurement, and process characteristics are discussed within five categories: bioenergy, biofuels, commodity biochemicals, fine and specialty biochemicals, and biomaterials. Several examples of biorefinery strategies are discussed to illustrate these concepts.
Failure to rescue as a source of variation in hospital mortality after hepatic surgery
Authors: Spolverato G , Ejaz A , Hyder O , Kim Y , Pawlik T M 
Published: April 2014

Abstract

Background
The mechanisms that underlie the association between high surgical volume and improved outcomes remain uncertain. This study examined the impact of complications and failure to rescue patients from these complications on mortality following hepatic resection.

Methods
The Nationwide Inpatient Sample was used to identify patients who had liver surgery between 2000 and 2010. Hospital volume was stratified into tertiles (low, intermediate and high). Rates of major complications, failure to rescue and mortality following hepatic surgery were compared.

Results
Some 9874 patients were identified. The major complication rate was 19·6 per cent in low-volume, 19·3 per cent in intermediate-volume and 16·6 per cent in high-volume hospitals (P &lt; 0·001). Most common major complications included respiratory insufficiency or failure (8·8 per cent), acute renal failure (4·2 per cent) and gastrointestinal bleeding (3·9 per cent), with each of these complications being less common in high-volume hospitals (P &lt; 0·050). The incidence of major morbidity following hepatectomy remained the same over the past decade, but failure to rescue patients from these complications decreased (P = 0·011). The overall inpatient mortality rate following liver surgery was 3·2 per cent (3·8, 3·6 and 2·3 per cent for low-, intermediate- and high-volume hospitals respectively; P &lt; 0·001). The rate of failure to rescue (death after a complication) was higher at low- and intermediate-volume hospitals (16·8 and 16·1 per cent respectively) compared with high-volume hospitals (11·8 per cent) (P = 0·032). After accounting for patient and hospital characteristics, patients treated at low-volume hospitals who had a complication were 40 per cent more likely to die than patients with a complication in a high-volume hospital (odds ratio 1·40, 95 per cent confidence interval 1·02 to 1·93).

Conclusion
The risk of death following hepatic surgery is lower at high-volume hospitals. The reduction in mortality appears to be the result of both lower complication rates and a better ability in high-volume hospitals to rescue patients with major complications.