bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subseasonal variations in spatial signatures of ENSO on the Indian summer monsoon from 1901 to 2009
Authors: Gill Emily C. , Rajagopalan Balaji , Molnar Peter 
Published: July 2015

AbstractCorrelations of 1° by 1° seasonal rainfall with Pacific sea surface temperatures (SSTs) reveal spatially distinct teleconnections between El Niño–Southern Oscillation (ENSO) and Indian summer monsoon rainfall over the full monsoon season, as well as three subseasons. Over the full season (June–September), Pacific SSTs correlate with rainfall in Western India more than that in Eastern India. This spatial signature shifts as the monsoon progresses through early (June), middle or peak (July–August), and late (September) subseasons. Specifically, a 1°C cooling of the central equatorial Pacific (i.e., La Niña conditions) can result in the following: ∼70–100% increase in precipitation in north central Indian and the Indo‐Gangetic Plains during the early season, ∼30–80% increase peak season precipitation in south central India and northwestern Rajasthan, and ∼60–100% increase in late season precipitation in northern, northwestern, and central India. Furthermore, the spatial signatures between La Niña and El Niño are asymmetric in that for a particular location, the enhancement and suppression of rainfall associated with La Niña and El Niño conditions, respectively, are not equal. El Niño suppresses peak season rainfall in the south central and northwestern Rajasthan regions more than La Niña enhances it, but the opposite occurs during the late season in northern, northwestern, and central India. Additionally, the correspondence of minima (maxima) in anomalies of velocity potential aloft with maxima (minima) at 925 mb and with positive (negative) surface pressure anomalies suggests that anomalous subsidence (ascent) occurs in July–September during El Niño (La Niña) times. In the early season, however, patterns of velocity potential composites suggest a region of descent (ascent) over the western equatorial Indian Ocean, along with a region of ascent (descent) over the Indian subcontinent that exists only during the early season but not during the peak or late season. These patterns are consistent with the hypothesis that local Hadley cell circulation affects pressure and thus rainfall during the early season but that a larger‐scale mechanism, such as eastward or westward shifts in the Walker circulation, may be more responsible for teleconnections seen throughout the remainder of the season. These findings indicate that focusing monsoon forecasting efforts on these regions and on subseasonal periods while incorporating ENSO asymmetries will yield useful and skillful regional forecasts, compared to the declining utility and skill of all‐India summer monsoon rainfall.
Extended observations of polar mesosphere winter echoes over Andøya (69°N) using MAARSY
Authors: Latteck R. , Strelnikova I. 
Published: July 2015

AbstractContinuous observations of Polar Mesosphere Winter Echoes (PMWE) have been conducted at the Norwegian island Andøya (69.30°N, 16.04°E) since autumn 2004 using the ALWIN VHF radar (until 2008) and the Middle Atmosphere Alomar Radar System (MAARSY) (since 2011). Using the more sensitive MAARSY compared to the ALWIN radar results in more detections characterized by smaller volume reflectivity values down to 4·10−18m−1 and a greater altitudinal coverage, 50–88 km compared to previous observations between 65 and 75 km. The results obtained by MAARSY show that the PMWE season starts clearly at the beginning of September with a mean seasonal occurrence rate of about 16%, but a strong seasonal variability with maxima up to 70% in the seasonal variation of the individual years. The end of the winter season is hard to determine since mesospheric echoes have also been observed below altitudes of 80km during nonwinter months, particularly around the end of May, i.e., the beginning of the polar mesospheric summer echo season, indicating that the physical mechanism for creating the lower mesospheric echoes is present during the early summer months as well.
The possible impact of urbanization on a heavy rainfall event in Beijing
Authors: Yu Miao , Liu Yimin 
Published: July 2015

AbstractThe impact of urbanization on a heavy rainfall event that occurred in Beijing on 21 July 2012 was investigated using version 3.6.1 of the Weather Research and Forecasting Model coupled with a multilayer urban canopy model. High‐resolution land use data for Beijing in 2010 with modified urban parameterization were introduced into the model. Evaluation showed that the simulation result generally agreed well with observations. Two sensitivity tests with different urban high‐resolution land use scenarios were employed to analyze the impact of urban expansion on this rainfall event. The simulation results confirmed that urbanization expansion played an important role in the distribution and intensity of precipitation for this extreme event. Urbanization led to total precipitation increasing in upstream and downstream directions. The start time of the precipitation process was advanced by 1 h, and the duration became longer due to the influence of urbanization. Moreover, urbanization caused the spatial distribution of precipitation to become more concentrated. The total precipitation amount above 250 mm and the frequency of precipitation intensity above 40 h−1 mm are both increased. The results of this study show that urbanization plays a significant role in frontal‐type rainfall.
A merging scheme for constructing daily precipitation analyses based on objective bias‐correction and error estimation techniques
Authors: Nie Suping , Luo Yong , Wu Tongwen , Shi Xueli , Wang Zaizhi 
Published: July 2015

AbstractA new merging scheme (referred to as HL‐OI) was developed to combine daily precipitation data from high‐resolution gauge (HRG) observations, The Climate Prediction Center morphing technique (CMORPH) satellite estimates, and National Centers for Environmental Prediction (NCEP) numerical simulations over China to perform reliable high‐resolution daily precipitation analyses. The scheme is designed using a three‐step strategy of removing systemic biases, reducing random errors, quantitatively estimating error variances, and combining useful information from each data source. First, a cumulative distribution function matching procedure is adopted to reduce biases and provide unbiased background fields for the following merging processes. Second, the developed error estimation algorithm is implemented to quantify both the background and observation errors from the background departures. Third, the bias‐corrected NCEP and CMORPH data are combined with the HRG data using the optimal interpolation (OI) objective analysis technique. The magnitudes and spatial structures of both observation errors and background errors can be estimated successfully. Results of cross‐validation experiments show that the HL‐OI scheme effectively removes most of systemic biases and random errors in the background fields compared to the independent gauge observations and is robust even with imperfect background fields. The HL‐OI merging scheme significantly improves the temporal variations, agreements between the spatial patterns, frequency, and locations of daily precipitation occurrences. When information from gauge observations, satellite estimates, and model simulations are combined simultaneously, the merged multisource analyses perform better than dual‐source analyses. These results indicate that each independent information source of daily precipitation contributes to improving the quality of the final merged analyses under the framework of HL‐OI scheme.
Differences in pedotransfer functions of bulk density lead to high uncertainty in soil organic carbon estimation at regional scales: Evidence from Chinese terrestrial ecosystems
Authors: Xu L. , He N. P. , Yu G. R. , Wen D. , Gao Y. , He H. L. 
Published: July 2015

AbstractAccurate estimation of soil organic carbon (SOC) storage is important for evaluating carbon sequestration of terrestrial ecosystems at regional scale. How the selected pedotransfer functions (PTFs) of bulk density (BD) influence the estimates of SOC storage is still unclear at large scales, although BD is an important parameter in all equations. Here we used data from the second national soil survey in China (8210 soil profiles) to evaluate the influence of eight selected PTFs on the estimation of SOC storage. The results showed that different PTFs may result in a higher uncertainty of SOC storage estimation and the coefficient of variation (CV, %) for the eight PTFs varied from 10.61% to 70.46% (mean = 12.75%). The observed CV values were higher in the 0–20 cm layer (12.48%) than in the 20–100 cm layer (10.05%). CV values were relatively stable (10–15%) when SOC content ranged from 0.13% to 3.45%. The findings indicate that PTFs may be used cautiously in soils with higher or lower SOC content. Estimates of SOC storage in the 0–100 cm soil layer varied from 67.19 to 95.97 Pg C in the eight PTFs in China, with an average of 87.36 ± 8.93 Pg C (CV = 10.23%). Our findings provide the insight that differences in PTFs are important sources of uncertainty in SOC estimates. The development of better PFTs, or the integration of various PFTs, is essential to accurately estimate SOC storage at regional scales.
The effects of hydrologic fluctuation and sulfate regeneration on mercury cycling in an experimental peatland
Authors: Coleman Wasik J. K. , Engstrom D. R. , Mitchell C. P. J. , Swain E. B. , Monson B. A. , Balogh S. J. , Jeremiason J. D. , Branfireun B. A. , Kolka R. K. , Almendinger J. E. 
Published: July 2015

AbstractA series of severe droughts during the course of a long‐term, atmospheric sulfate‐deposition experiment in a boreal peatland in northern Minnesota created a unique opportunity to study how methylmercury (MeHg) production responds to drying and rewetting events in peatlands under variable levels of sulfate loading. Peat oxidation during extended dry periods mobilized sulfate, MeHg, and total mercury (HgT) to peatland pore waters during rewetting events. Pore water sulfate concentrations were inversely related to antecedent moisture conditions and proportional to past and current levels of atmospheric sulfate deposition. Severe drying events caused oxidative release of MeHg to pore waters and resulted in increased net MeHg production likely because available sulfate stimulated the activity of sulfate‐reducing bacteria, an important group of Hg‐methylating bacteria in peatlands. Rewetting events led to increased MeHg concentrations across the peatland, but concentrations were highest in peat receiving elevated atmospheric sulfate deposition. Dissolved HgT concentrations also increased in peatland pore waters following drought but were not affected by sulfate loading and did not appear to be directly controlled by dissolved organic carbon mobilization to peatland pore waters. Peatlands are often considered to be sinks for sulfate and HgT in the landscape and sources of MeHg. Hydrologic fluctuations not only serve to release previously sequestered sulfate and HgT from peatlands but may also increase the strength of peatlands as sources of MeHg to downstream aquatic systems, particularly in regions that have experienced elevated levels of atmospheric sulfate deposition.
Deformation of erosive and accretive forearcs during subduction of migrating and non‐migrating aseismic ridges: Results from 3‐D finite element models and application to the Central American, Peruvian, and Ryukyu margins
Authors: Zeumann Stefanie , Hampel Andrea 
Published: July 2015

AbstractSubduction of aseismic oceanic ridges causes considerable uplift and deformation of the upper plate and may lead, for example, to the indentation of the forearc, the formation of marine terraces, or distinct fault patterns in the upper plate. Depending on the orientation of the ridge relative to the plate convergence direction, the ridge may either be stationary or migrate along the margin. Here we use three‐dimensional numerical models to investigate the tectonic evolution of forearcs affected by ridge subduction. In different experiments, we distinguish between migrating/non‐migrating ridges and accretive/erosive margins, respectively. Our results reveal that displacement and strain fields above migrating and non‐migrating ridges are asymmetric with respect to the ridge axis unless both ridge and plate convergence direction are perpendicular to the trench. As the asymmetric deformation pattern shifts along the margin through time, uplift caused by the underthrusting ridge is followed by subsidence when the ridge crest passed by, and regions initially experiencing shortening may subsequently undergo extension and vice versa. If the forearc comprises an accretionary prism, the ridge‐induced reentrant is larger than those in models with erosive forearcs and strain localizes in the frontal part of the wedge. Additional models with a setup adjusted to the Cocos and Gagua Ridges provide constraints on the onset of their subduction at the Central American and Ryukyu margins at ~2 Ma and 1 Ma, respectively. Displacement and strain fields from a model for the Nazca Ridge collision zone show good agreement with geological data from marine terraces and Quaternary faulting.
Precise Design of Phosphorescent Molecular Butterflies with Tunable Photoinduced Structural Change and Dual Emission
Authors: Zhou Chenkun , Tian Yu , Yuan Zhao , Han Mingu , Wang Jamie , Zhu Lei , Tameh Maliheh Shaban , Huang Chen , Ma Biwu 
Published: July 2015

AbstractPhotoinduced structural change (PSC) is a fundamental excited‐state dynamic process in chemical and biological systems. However, precise control of PSC processes is very challenging, owing to the lack of guidelines for designing excited‐state potential energy surfaces (PESs). A series of rationally designed butterfly‐like phosphorescent binuclear platinum complexes that undergo controlled PSC by Pt–Pt distance shortening and exhibit tunable dual (greenish‐blue and red) emission are herein reported. Based on the Bell–Evans–Polanyi principle, it is demonstrated how the energy barrier of the PSC, which can be described as a chemical‐reaction‐like process between the two energy minima on the first triplet excited‐state PES, can be controlled by synthetic means. These results reveal a simple method to engineer the dual emission of molecular systems by manipulating PES to control PSC.
Fully degradable antibacterial poly(ester‐phosphoester)s by ring‐opening polymerization, “click” chemistry, and quaternization
Authors: Yao Xuxia , Du Hong , Xu Ning , Sun Shuai , Zhu Weipu , Shen Zhiquan 
Published: July 2015

ABSTRACTFully degradable cationic poly(ester‐phosphoester)s with antibacterial properties were prepared by a combination of ring‐opening polymerization (ROP) and “click” reaction. First, poly(ester‐phosphoester)s‐bearing alkynyl groups were synthesized by the ring‐opening copolymerization of 2‐(2‐propynyloxy)−2‐oxo‐1,3,2‐dioxaphospholane (propynyl ethylene phosphate, PEP) and ε‐caprolactone (CL) using lanthanum tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s (La(DBMP)3) as the catalyst. 2‐Azido‐N,N‐dimethylethanamine (DMEAN3) was then attached to the copolymers by “click” reaction, resulting in poly(ester‐phosphoester)s with pendant tertiary amines. After the quaternization reactions between the copolymer and various alkyl bromides, cationic poly(ester‐phosphoester)s containing ammonium groups were obtained. Optical density (OD) measurement shows that the cationic copolymers have excellent antibacterial activity, which makes them potential candidates as biomaterials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42647.
Thermoplastic softening behavior of organically modified polyoxotitanates: Effects of the amount of water and benzoylacetone for hydrolyzing alkoxides
Authors: Oda Shinya , Kozuka Hiromitsu , Uchiyama Hiroaki 
Published: July 2015

ABSTRACTOrganically modified polyoxotitanates were prepared by hydrolyzing titanium tetra‐n‐butoxide in the presence of benzoylacetone (BzAc) in solution at Ti(OC4H9)4 : BzAc : H2O : CH3COCH3 mole ratios of 1 : (1 or 2) : (1 or 10) : 20. The solutions were concentrated at 80°C and dried at 140°C in N2 flow, producing transparent and yellow materials of BzAc‐modified polyoxotitanate. The materials had refractive indices of ∼1.7 and exhibited thermoplastic softening at temperatures below 70°C. Low contents of BzAc and high contents of H2O in solution led to higher softening temperatures of the materials, indicating the tunability of the softening temperature. Gel permeation chromatographic analyses showed that the higher softening temperatures originated mainly from polymerized species of higher molecular weights that were generated by hydrolysis and condensation reactions promoted by the low BzAc and high H2O contents in solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42653.
Ethylene polymerization with homogeneous and heterogeneous catalysts based on bis(4‐fluorophenyl)methyl‐substituted bis(imino)pyridyliron complexes
Authors: Semikolenova Nina V. , Zhang Wenjuan , Zakharov Vladimir A. , Bryliakov Konstantin P. , Sun Wen‐Hua 
Published: July 2015

ABSTRACTA series of bis(4‐fluorophenyl)methyl‐substituted bis(imino)pyridyliron chloride complexes were immobilized on oxide supports. The kinetics of ethylene polymerization by both homogeneous and heterogeneous systems was followed, the catalysts mostly demonstrating high activities. The effect of the ligands nature and reaction conditions on the catalytic activities and molecular weights of the resultant polyethylenes was examined. In contrast to homogeneous systems, the supported iron complexes were found to exhibit high and stable activity upon activation with triisobutyl aluminium, producing high‐molecular‐weight polyethylene with good morphology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42674.
Effect of kaolin nanofiller and processing conditions on the structure, morphology, and biofilm development of polylactic acid
Authors: Segura González Edwin A. , Olmos Dania , González‐Gaitano Gustavo , Orgaz Belén , González‐Benito Javier 
Published: July 2015

ABSTRACTThe effect of high energy ball milling, HEBM, and the presence of kaolin on the structure, morphology, and biofilm development of polylactic acid, PLA, were studied. Biofilm development was evaluated in terms of structural and/or morphological variations so as the sole presence of kaolin. Composites based on PLA filled with kaolin were prepared by HEBM followed by hot pressing to obtain films. Structure was studied by X‐ray diffraction and Fourier transformed infrared spectroscopy whereas morphology was inspected by scanning electron microscopy and atomic force microscopy. To study biofilm development on the surface of these materials, Pseudomonas fluorescens B52 were used. The shear forces from the milling process favor kaolin dispersion within the PLA. Longer milling times and cryogenic conditions improve clay dispersion. Subsequent hot pressing process enhances the most ordered structure of PLA (α‐phase) which is also favored with previous milling at longer times and under cryogenic conditions. Changes in P. fluorescens biofilm development are mainly due to modifications of surface properties induced by structural variations, being the most ordered structures those which better support bacterial adhesion and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42676.
A dynamic mechanical analysis of the interfacial changes induced from both the reinforcement and the matrix sides in polypropylene/surface modified talc composites
Authors: García‐Martínez Jesús María , Taranco Jesús , Areso Susana , Collar Emilia P. 
Published: July 2015

ABSTRACTThe interfacial changes associated with a series of polypropylene based composite materials with modified interphases from the reinforcement side, from the matrix side and both were studied by following their dynamic mechanical behavior. Composites consisted in an isotactic polypropylene (iPP) matrix, a series of talc with different surface functionalities (hydroxyl, chloride, n‐butyl amine, and silanes) and a commercial interfacial agent form the matrix side (iPP‐SA with 5% of grafts). A comprehensive interpretation of the link existing between the dynamic mechanical responses of the series of 75/25 iPP/talc composites and the molecular relaxation spectrum occurring in the polymer phase of the composites is made with emphasis on the role played by the interfacial modifications performed from each and both sides of the interphase. Dynamic mechanical analysis has been used here to study how the intended interfacial modifications affected the behavior of the composites. The efficiency of the interfacial phenomena is discussed from a phenomenological point of view as well as by considering classical criteria such as the glass transition temperature and the glass to rubbery transition. Finally, a correlation between mechanical parameters from the microscopic scale and others from the macroscopic scale appears to emerge. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42678.
Numerical and experimental studies for gas assisted extrusion forming of molten polypropylene
Authors: Ren Zhong , Huang Xingyuan , Liu Hesheng , Deng Xiaozhen , He Jiantao 
Published: July 2015

ABSTRACTIn this study, the experiments of gas‐assisted extrusion (GAE) for molten polypropylene were carried out under different gas pressures, the different extrudate deformations and sharkskin defects of melt were observed. To ascertain the effects of gas on melt extrusion, non‐isothermal numerical simulation of GAE based on gas/melt two‐phase fluid model was proposed and studied. In the simulations, the melt extruded profile, physical field distributions (velocities, pressure drop, and first normal stress difference) were obtained. Numerical results showed that the deformation degree of melt increased with increasing gas pressure, which was in good agreement with experimental results. It was demonstrated that the influence of gas pressure on the melt extrusion could be well reflected by GAE simulation based on gas/melt two‐phase fluid model rather than simplified‐GAE (SGAE) based on full‐slip wall boundary condition used in the past time. Experimental and numerical results demonstrate that the gas pressure induced first normal stress difference is the main reason of triggering flow behavior changes, extrudate deformations, and sharkskin defects of melt. Therefore, the reasonable controlling of gas pressure is a key in practice of GAE, and the gas layer and its influence should be considered in GAE numerical simulation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42682.