bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of branching brittle and ductile shear zones: A numerical study
Authors: Meyer Sven Erik , Kaus Boris J. P. , Passchier Cees 
Published: May 2017

AbstractContinental collision zones are usually associated with large‐scale strike‐slip shear zones. In most cases, these shear zones are complex and consist of multiple strands, varying in width, length, and total displacement. Here we present 2‐D numerical models to simulate the formation of such shear zones at different depth levels within the crust, under either brittle (frictional/plastic) or ductile conditions. Localization of shear zones is initiated by a material contrast (heterogeneity) of the material parameters. We systematically test the rate of strain weakening in brittle and in ductile regimes to understand its influence on the development of shear zone networks. Our simulations suggest that the development of antithetic faults in a brittle shear zone system is closely linked to a decrease in the angle of friction during deformation. In general, variation of the strain weakening also has a significant influence on ductile shear zones. Numerical results show that the geometry and thickness of the localized high strain zone are especially affected by weakening mechanisms during deformation. Furthermore, the interconnection and interaction of the shear strands lead to a more complex kinematic pattern, which lead to a local change in the maximum principal stress axis. These interaction of shear strands may explain the occurrence of shear‐related structures (e.g., folds) or differing characteristics of shear zones, such as the thickness of shear zones or the orientation of the faults to the stress field, which are consistent with field observations.
The impact of alkenone degradation on paleothermometry: A model‐derived assessment
Authors: Freitas Felipe S. , Pancost Richard D. , Arndt Sandra 
Published: May 2017

AbstractThe
proxy for past sea surface temperature (SST) is based on the unsaturation ratio of C37 alkenones. It is considered a diagenetically robust proxy, but biases have been invoked because the index can be altered by preferential degradation of the C37:3 alkenone, resulting in higher reconstructed SST. However, alkenone degradation rate constants are poorly constrained, making it difficult to evaluate the plausibility of such a bias. Therefore, we quantitatively assessed the effect of (1) different alkenone degradation rate constants; (2) differential degradation factors between diunsaturated and triunsaturated C37 alkenones; (3) and initial
values on the
paleothermometer for two depositional environments (shelf and upper slope), by means of a reaction‐transport model (RTM). RTM results reveal that preferential degradation of C37:3 can potentially alter the original signal of the
paleothermometer, but SST biases (ΔSST) are largely within
calibration error (ΔSST <1.5°C) assuming realistic model parameters. The magnitude of ΔSST is largely determined by the degradation rate constant, but it also increases with higher differential degradation factors. Additionally, initial
values exert a nonlinear influence on the extent of potential SST bias, with midrange values (0.4 <
< 0.6) being most sensitive. The most significant changes occur in the shallowest sediment layers and are attenuated with burial time/depth. Scenarios where ΔSST >1.5°C are associated with marked downcore decreases in alkenone concentration. Consequently, we caution against the interpretation of
indices when extensive degradation results in very low alkenone concentrations (<5 ng g−1).
A CO2‐gas precursor to the March 2015 Villarrica volcano eruption
Authors: Aiuppa Alessandro , Bitetto Marcello , Francofonte Vincenzo , Velasquez Gabriela , Parra Claudia Bucarey , Giudice Gaetano , Liuzzo Marco , Moretti Roberto , Moussallam Yves , Peters Nial , Tamburello Giancarlo , Valderrama Oscar. A. , Curtis Aaron 
Published: May 2017

AbstractWe present here the first volcanic gas compositional time‐series taken prior to a paroxysmal eruption of Villarrica volcano (Chile). Our gas plume observations were obtained using a fully autonomous Multi‐component Gas Analyser System (Multi‐GAS) in the 3 month‐long phase of escalating volcanic activity that culminated into the 3 March 2015 paroxysm, the largest since 1985. Our results demonstrate a temporal evolution of volcanic plume composition, from low CO2/SO2 ratios (0.65‐2.7) during November 2014‐January 2015 to CO2/SO2 ratios up to ≈ 9 then after. The H2O/CO2 ratio simultaneously declined to <38 in the same temporal interval. We use results of volatile saturation models to demonstrate that this evolution toward CO2‐enriched gas was likely caused by unusual supply of deeply sourced gas bubbles. We propose that separate ascent of over‐pressured gas bubbles, originating from at least 20‐35 MPa pressures, was the driver for activity escalation toward the 3 March climax.
Rock magnetic and geochemical evidence for authigenic magnetite formation via iron reduction in coal‐bearing sediments offshore Shimokita Peninsula, Japan (IODP Site C0020)
Authors: Phillips Stephen C. , Johnson Joel E. , Clyde William C. , Setera Jacob B. , Maxbauer Daniel P. , Severmann Silke , Riedinger Natascha 
Published: May 2017

AbstractSediments recovered at Integrated Ocean Drilling Program (IODP) Site C0020, in a fore‐arc basin offshore Shimokita Peninsula, Japan, include numerous coal beds (0.3–7 m thick) that are associated with a transition from a terrestrial to marine depositional environment. Within the primary coal‐bearing unit (∼2 km depth below seafloor) there are sharp increases in magnetic susceptibility in close proximity to the coal beds, superimposed on a background of consistently low magnetic susceptibility throughout the remainder of the recovered stratigraphic sequence. We investigate the source of the magnetic susceptibility variability and characterize the dominant magnetic assemblage throughout the entire cored record, using isothermal remanent magnetization (IRM), thermal demagnetization, anhysteretic remanent magnetization (ARM), iron speciation, and iron isotopes. Magnetic mineral assemblages in all samples are dominated by very low‐coercivity minerals with unblocking temperatures between 350 and 580°C that are interpreted to be magnetite. Samples with lower unblocking temperatures (300–400°C), higher ARM, higher‐frequency dependence, and isotopically heavy δ56Fe across a range of lithologies in the coal‐bearing unit (between 1925 and 1995 mbsf) indicate the presence of fine‐grained authigenic magnetite. We suggest that iron‐reducing bacteria facilitated the production of fine‐grained magnetite within the coal‐bearing unit during burial and interaction with pore waters. The coal/peat acted as a source of electron donors during burial, mediated by humic acids, to supply iron‐reducing bacteria in the surrounding siliciclastic sediments. These results indicate that coal‐bearing sediments may play an important role in iron cycling in subsiding peat environments and if buried deeply through time, within the subsequent deep biosphere.
Daytime ionospheric longitudinal gradients seen in the observations from a regional BeiDou GEO receiver network
Authors: Huang Fuqing , Lei Jiuhou , Dou Xiankang 
Published: May 2017

AbstractMany studies have devoted to the longitudinal variations of the ionosphere globally. However, the ionospheric longitudinal variations in a small region are rarely reported. In this paper, we for the first time use total electron content (TEC) data from a BeiDou geostationary orbit (GEO) receiver network to observe and investigate ionospheric longitudinal variations within the zonal scale of 1000 km over Central China (112°–122°E, 27°–31°N; 20°–24°N magnetic latitudes) during the period from June 2015 to December 2016. The BeiDou GEO TEC provides a good data set to study longitudinal variations, compared with non‐GEO TEC, without contaminating the spatial variations and elevation changes due to satellite motion. Pronounced daytime longitudinal gradients within the distance of 1000 km are present in BeiDou GEO TEC. It was found that the TEC is generally larger in the west than in the east. The maximum TEC longitudinal gradient can reach 45 total electron content unit (TECU; 1 TECU = 1016 el m−2). For most events, the obvious daytime longitudinal gradients are accompanied by the TEC enhancement. The occurrence rate of daytime longitudinal gradients under different geomagnetic activities is similar, whereas strong daytime longitudinal gradients mainly occur under the moderate and strong disturbance geomagnetic activities. These observations suggest that the electric field disturbances could have significant effects on producing the observed ionospheric longitudinal gradients.
Periodic sediment shift in migrating ripples influences benthic microbial activity
Authors: Zlatanović Sanja , Fabian Jenny , Mendoza‐Lera Clara , Woodward K. Benjamin , Premke Katrin , Mutz Michael 
Published: May 2017

AbstractMigrating bedforms have high levels of particulate organic matter and high rates of pore water exchange, causing them to be proposed as hot spots of carbon turnover in rivers. Yet, the shifting of sediments and associated mechanical disturbance within migrating bedforms, such as ripples, may stress and abrade microbial communities, reducing their activity. In a microcosm experiment, we replicated the mechanical disturbances caused by the periodic sediment shift within ripples under oligotrophic conditions. We assessed the effects on fungal and bacterial biomass ratio (F:B), microbial community respiration (CR), and bacterial production (BCP) and compared with stable undisturbed sediments. Interactions between periodic mechanical disturbance and sediment‐associated particulate organic matter (POM) were tested by enriching sediments collected from migrating ripples with different qualities of POM (fish feces, leaf litter fragments and no addition treatments). F:B and BCP were affected by an interaction between mechanical disturbance and POM quality. Fish feces enriched sediments showed increased F:B and BCP compared to sediments with lower POM quality and responded with a decrease of F:B and BCP to sediment disturbance. In the other POM treatments F:B and BCP were not affected by disturbance. Microbial respiration was however reduced by mechanical disturbance to similar low activity levels regardless of POM qualities added, whereas fish feces enriched sediment showed short temporary boost of CR. With the worldwide proliferation of migrating sand ripples due to massive catchment erosion, suppressed mineralization of POM will increasingly affect stream metabolism, downstream transport of POM and carbon cycling from reach to catchment scale.
Palladium‐Catalyzed Regioselective Direct Arylation of Benzofurazans at the C‐4 Position
Authors: Idris Imane , Derridj Fazia , Soulé Jean‐François , Doucet Henri 
Published: May 2017

AbstractThe palladium‐catalyzed direct arylation of benzofurazans with aryl bromides to access 4‐arylbenzofurazans proceeds in moderate‐to‐high yields using phosphine‐free palladium acetate as the catalyst and potassium acetate as an inexpensive base. A wide variety of (hetero)aryl bromides, including bromopyridine and bromothiophene derivatives has been successfully employed. Palladium‐catalyzed one‐pot C‐4,C‐7‐diarylation of benzofurazan was also achieved using a larger amount of aryl bromide. Moreover, the derivatization of 4‐arylbenzofurazans into 4‐arylquinaxolines is also reported.magnified image
Molecularly imprinted fluorescent probe based on hydrophobic CdSe/ZnS quantum dots for the detection of methamidophos in fruit and vegetables
Authors: Liu Xueyan , Liu Qiurui , Kong Feifan , Qiao Xuguang , Xu Zhixiang 
Published: May 2017

AbstractIn this study, a molecularly imprinted polymer (MIP)‐fluorescent probe based on hydrophobic CdSe/ZnS quantum dots (CdSe/ZnS@MIP) was designed and synthesized by bulk polymerization for detecting methamidophos (MAP). The CdSe/ZnS@MIP was characterized by Fourier‐transform infrared spectroscopy, thermo‐gravimetric analysis and adsorption properties, and it exhibited good adsorption capacity and fluorescent stability, and excellent selectivity. Under optimal conditions, the fluorescence showed a good linear decrease in the range of 3.50 × 10−7–0.71 × 10−3 mol/L with a correlation coefficient of 0.995. The limit of detection of the fluorescent probe was 9.16 × 10−8 mol/L, and the relative standard deviation of the method for nine replicate analyses of 4.0 × 10−6 mol/L MAP was 4.1%. Apple and pear samples spiked with MAP at three levels were extracted and determined by the presented method with good recoveries (89.7%–94.9%). The accuracy of the method was verified by gas chromatography for the detection of kidney beans, leek and cucumber samples, and no significant difference was observed for the results of two methods.
How Robust Are Studies in the American Board of Emergency Medicine Maintenance of Certification Lifelong Learning and Self‐assessment? An Examination of Fragility and Bias of Included Randomized Controlled Trials
Authors: Davis Philip J. , Butler Michael , Magee Kirk , Thoma Brent , Nickson Christopher P. , Trueger N. Seth 
Published: May 2017

AbstractObjectiveCritics have raised concerns regarding the validity of maintenance of certification (MOC) programs. We sought to examine the quality of the randomized controlled trials (RCTs) selected for the lifelong learning and self‐assessment (LLS) component of the American Board of Emergency Medicine (ABEM) MOC program.MethodsWe systematically reviewed the ABEM LLS reading lists from 2004 to 2017 to identify RCTs with dichotomous outcomes and superiority designs. A fragility index (FI) was calculated using Fisher's exact test for all statistically significant dichotomous outcomes. Bivariate correlation was performed to examine associations between the FI and RCT study characteristics. Each included study was evaluated with the Cochrane Collaboration risk‐of‐bias (ROB) tool.ResultsThirteen superiority RCTs with dichotomous outcomes were included in the 2004–2017 LLS reading lists. Ten had a statistically significant outcome, and the majority were robust and at low ROB. The median trial size was 511 patients (interquartile range [IQR] = 251–1,517), and the median FI was 10 (IQR = 7–18); i.e., if 10 patients in the treatment arm had not had events, the results would not have been statistically significant.ConclusionsThe majority of RCTs included in the LLS are robust and at low ROB.
Pre‐fibrotic/early primary myelofibrosis vs. WHO‐defined essential thrombocythemia: The impact of minor clinical diagnostic criteria on the outcome of the disease
Authors: Jeryczynski Georg , Thiele Jürgen , Gisslinger Bettina , Wölfler Albert , Schalling Martin , Gleiß Andreas , Burgstaller Sonja , Buxhofer‐Ausch Veronika , Sliwa Thamer , Schlögl Ernst , Geissler Klaus , Krauth Maria‐Theresa , Nader Alexander , Vesely Michael , Simonitsch‐Klupp Ingrid , Müllauer Leonhard , Beham‐Schmid Christine , Gisslinger Heinz 
Published: May 2017

AbstractThe 2016 revised WHO criteria for the diagnosis of pre‐fibrotic/early primary myelofibrosis (pre‐PMF) require at least one of the following four borderline expressed minor clinical criteria: anemia, leukocytosis, elevated lactate dehydrogenase and splenomegaly. In this study, we evaluated the relative frequency of these four criteria in a group of 170 pre‐PMF patients and compared them to 225 ET cases. More than 91% of pre‐PMF cases showed one or more of these features required for diagnosis, by contrast with only 48% of ET patients. According to clinical data the cumulative risk of progression to advanced/overt PMF in pre‐PMF was 36.9% after 15 years. After fitting cox regression models to analyze the impact of the minor criteria on overall survival, only leukocytosis remained as a significant predictor of survival in both pre‐PMF and ET. Molecular characterization showed differences in survival in pre‐PMF but not ET, with CALR being a more favorable mutation than JAK2. The different outcome of pre‐PMF versus ET and associated molecular genetic data supports the concept of two different entities, rather than a continuum of the same disease. Although slightly less than 50% of ET patients also show one or more minor clinical criteria, accurate distinction between ET and pre‐PMF is possible by following an integrated approach including histomorphological diagnosis and presence of minor clinical criteria.
Superior Alkylating Agents for Bulky Esters/Ketones via Strontium‐Mediated Barbier‐Type Reaction
Authors: Ohmura Satoshi D. , Miyazaki Yasuaki , Kanehiro Daisuke , Yamaguchi Yuka , Kitakata Saki , Tateda Sawa , Nishizawa Takahiro , Shimoda Ryosuke , Nagaoka Gen , Ueno Masaharu , Miyoshi Norikazu 
Published: May 2017

AbstractAn efficient method has been developed for the Barbier‐type alkylation reaction of bulky esters or ketones in the presence of metallic strontium and alkyl iodides. The reaction proceeded smoothly at ambient temperature to afford the fully alkylated corresponding alcohols in better yield than those obtained when using the corresponding Grignard reagents. The method is especially effective for introducing isobutyl or neopentyl groups into phenyl or adamantyl skeletons.
Structural Basis for Copper–Oxygen Mediated C−H Bond Activation by the Formylglycine‐Generating Enzyme
Authors: Meury Marcel , Knop Matthias , Seebeck Florian P. 
Published: May 2017

AbstractThe formylglycine‐generating enzyme (FGE) is a unique copper protein that catalyzes oxygen‐dependent C−H activation. We describe 1.66 Å‐ and 1.28 Å‐resolution crystal structures of FGE from Thermomonospora curvata in complex with either AgI or CdII providing definitive evidence for a high‐affinity metal‐binding site in this enzyme. The structures reveal a bis‐cysteine linear coordination of the monovalent metal, and tetrahedral coordination of the bivalent metal. Similar coordination changes may occur in the active enzyme as a result of CuI/II redox cycling. Complexation of copper atoms by two cysteine residues is common among copper‐trafficking proteins, but is unprecedented for redox‐active copper enzymes or synthetic copper catalysts.
Reversing Polarity: Carbonyl α‐Aminations with Nitrogen Nucleophiles
Authors: de la Torre Aurélien , Tona Veronica , Maulide Nuno 
Published: May 2017

AbstractThe synthesis of α‐amino carbonyl compounds is an important challenge in synthesis en route to biologically essential structures. While classical approaches involve the use of enol or enolate chemistries in combination with an electrophilic source of nitrogen, those strategies usually necessitate further transformations to reach the desired targets. In recent years, a new approach arose involving the direct use of nucleophilic sources of nitrogen along with an oxidant. This approach advantageously leads, in one‐pot, to the biologically relevant α‐amino compound without requiring further transformation. This review highlights the recent advances in the emerging field of oxidative α‐amination reactions using nucleophilic sources of nitrogen.
Black Tungsten Nitride as a Metallic Photocatalyst for Overall Water Splitting Operable at up to 765 nm
Authors: Wang Yu Lei , Nie Ting , Li Yu Hang , Wang Xue Lu , Zheng Li Rong , Chen Ai Ping , Gong Xue Qing , Yang Hua Gui 
Published: May 2017

AbstractSemiconductor photocatalysts are hardly employed for overall water splitting beyond 700 nm, which is due to both thermodynamic aspects and activation barriers. Metallic materials as photocatalysts are known to overcome this limitation through interband transitions for creating electron–hole pairs; however, the application of metallic photocatalysts for overall water splitting has never been fulfilled. Black tungsten nitride is now employed as a metallic photocatalyst for overall water splitting at wavelengths of up to 765 nm. Experimental and theoretical results together confirm that metallic properties play a substantial role in exhibiting photocatalytic activity under red‐light irradiation for tungsten nitride. This work represents the first red‐light responsive photocatalyst for overall water splitting, and may open a promising venue in searching of metallic materials as efficient photocatalysts for solar energy utilization.
Study on thermal oxidative stabilization reactions of poly(acrylonitrile‐co‐itaconic acid) copolymers synthesized at different polymerization stages
Authors: Fu Zhongyu , Liu Baijun , Zhang Huixuan 
Published: May 2017

ABSTRACTThe structural evolution of poly(acrylonitrile‐co‐itaconic acid) (PAI) copolymers synthesized at different polymerization stages during thermal oxidative stabilization (TOS) are quantitatively tracked by the attenuated total reflection Fourier transform infrared spectroscopy technology. The evolution of β‐amino nitrile and conjugated nitrile are quantitatively tracked by peak‐fitting technique during TOS. A procedure is developed to get the fine information of TOS reactions, especially to value qualitatively the length of cyclic or ladder structures. There is no distinguished difference of structural evolution of PAI copolymers synthesized at different polymerization stages during TOS process. The length of cyclic or ladder structures for all PAI copolymers possesses almost the same values and decreases gradually as the TOS proceeding. The termination of cyclization and the oxidative dehydrogenation become dominant in the late of TOS process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45245.
Glycated human albumin alters mitochondrial respiration in preadipocyte 3T3‐L1 cells
Authors: Baret Pascal , Le Sage Fanny , Planesse Cynthia , Meilhac Olivier , Devin Anne , Bourdon Emmanuel , Rondeau Philippe 
Published: May 2017

AbstractDiabetes and obesity are strongly associated with increased levels of circulating advanced glycation end products (AGEs) and reactive oxygen species (ROS). These two molecular phenomena affect the physiology of adipose tissue, a biological driver of the metabolic syndrome, leading to an inflammatory profile and insulin resistance, which could contribute to obesity/diabetes‐associated complications, such as cardiovascular diseases. Herein, we investigated the impact of AGEs on mitochondrial bioenergetics in murine preadipocyte cells (3T3‐L1) and cellular redox homeostasis. We show that incubation of preadipocytes with AGEs stimulates mitochondrial activity and respiration while inducing oxidative stress. This AGE‐induced intracellular ROS production was blocked by diphenylene iodonium, an NAD(P)H oxidase inhibitor. In parallel, antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase) were found to be activated upon AGE treatment. Our results suggest that AGE‐induced oxidative stress is generated by NAD(P)H oxidase and leads to a cellular proliferation arrest associated with enhanced mitochondrial metabolism and biogenesis, and with increased levels of ROS‐detoxifying enzymes, as well. These new data show how AGEs may be involved in hyperglycemia‐induced oxidative damage in preadipocytes and their potential links to diabetes progression. © 2017 BioFactors, 43(4):577–592, 2017