bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and evaluation of a physics‐based windblown dust emission scheme implemented in the CMAQ modeling system
Authors: Foroutan H. , Young J. , Napelenok S. , Ran L. , Appel K. W. , Gilliam R. C. , Pleim J. E. 
Published: February 2017

AbstractA new windblown dust emission treatment was incorporated in the Community Multiscale Air Quality (CMAQ) modeling system. This new model treatment has been built upon previously developed physics‐based parameterization schemes from the literature. A distinct and novel feature of this scheme, however, is the incorporation of a newly developed dynamic relation for the surface roughness length relevant to small‐scale dust generation processes. Through this implementation, the effect of nonerodible elements on the local flow acceleration, drag partitioning, and surface coverage protection is modeled in a physically based and consistent manner. Careful attention is paid in integrating the new windblown dust treatment in the CMAQ model to ensure that the required input parameters are correctly configured. To test the performance of the new dust module in CMAQ, the entire year 2011 is simulated for the continental United States, with particular emphasis on the southwestern United States (SWUS) where windblown dust concentrations are relatively large. Overall, the model shows good performance with the daily mean bias of soil concentrations fluctuating in the range of ±1 µg m−3 for the entire year. Springtime soil concentrations are in quite good agreement (normalized mean bias of 8.3%) with observations, while moderate to high underestimation of soil concentration is seen in the summertime. The latter is attributed to the issue of representing the convective dust storms in summertime. Evaluations against observations for seven elevated dust events in the SWUS indicate that the new windblown dust treatment is capable of capturing spatial and temporal characteristics of dust outbreaks.
Improvement of the prediction of surface ozone concentration over conterminous U.S. by a computationally efficient second‐order Rosenbrock solver in CAM4‐Chem
Authors: Sun Jian , Fu Joshua S. , Drake John , Lamarque Jean‐Francois , Tilmes Simone , Vitt Francis 
Published: February 2017

AbstractThe global chemistry‐climate model (CAM4‐Chem) overestimates the surface ozone concentration over the conterminous U.S. (CONUS). Reasons for this positive bias include emission, meteorology, chemical mechanism, and solver. In this study, we explore the last possibility by examining the sensitivity to the numerical methods for solving the chemistry equations. A second‐order Rosenbrock (ROS‐2) solver is implemented in CAM4‐Chem to examine its influence on the surface ozone concentration and the computational performance of the chemistry program. Results show that under the same time step size (1800 s), statistically significant reduction of positive bias is achieved by the ROS‐2 solver. The improvement is as large as 5.2 ppb in Eastern U.S. during summer season. The ROS‐2 solver is shown to reduce the positive bias in Europe and Asia as well, indicating the lower surface ozone concentration over the CONUS predicted by the ROS‐2 solver is not a trade‐off consequence with increasing the ozone concentration at other global regions. In addition, by refining the time step size to 180 s, the first‐order implicit solver does not provide statistically significant improvement of surface ozone concentration. It reveals that the better prediction from the ROS‐2 solver is not only due to its accuracy but also due to its suitability for stiff chemistry equations. As an added benefit, the computation cost of the ROS‐2 solver is almost half of first‐order implicit solver. The improved computational efficiency of the ROS‐2 solver is due to the reuse of the Jacobian matrix and lower upper (LU) factorization during its multistage calculation.
Experimental investigation of clogging dynamics in homogeneous porous medium
Authors: Shen Jikang , Ni Rui 
Published: February 2017

AbstractA 3‐D refractive‐index matching Lagrangian particle tracking (3D‐RIM‐LPT) system was developed to study the filtration and the clogging process inside a homogeneous porous medium. A small subset of particles flowing through the porous medium was dyed and tracked. As this subset was randomly chosen, its dynamics is representative of all the rest. The statistics of particle locations, number, and velocity were obtained as functions of different volumetric concentrations. It is found that in our system the clogging time decays with the particle concentration following a power law relationship. As the concentration increases, there is a transition from depth filtration to cake filtration. At high concentration, more clogged pores lead to frequent flow redirections and more transverse migrations of particles. In addition, the velocity distribution in the transverse direction is symmetrical around zero, and it is slightly more intermittent than the random Gaussian curve due to particle‐particle and particle‐grain interactions. In contrast, as clogging develops, the longitudinal velocity of particles along the mean flow direction peaks near zero because of many trapped particles. But at the same time, the remaining open pores will experience larger pressure and, as a result, particles through those pores tend to have larger longitudinal velocities.
Process connectivity in a naturally prograding river delta
Authors: Sendrowski Alicia , Passalacqua Paola 
Published: February 2017

AbstractRiver deltas are lowland systems that can display high hydrological connectivity. This connectivity can be structural (morphological connections), functional (control of fluxes), and process connectivity (information flow from system drivers to sinks). In this work, we quantify hydrological process connectivity in Wax Lake Delta, coastal Louisiana, by analyzing couplings among external drivers (discharge, tides, and wind) and water levels recorded at five islands and one channel over summer 2014. We quantify process connections with information theory, a branch of mathematics concerned with the communication of information. We represent process connections as a network; variables serve as network nodes and couplings as network links describing the strength, direction, and time scale of information flow. Comparing process connections at long (105 days) and short (10 days) time scales, we show that tides exhibit daily synchronization with water level, with decreasing strength from downstream to upstream, and that tides transfer information as tides transition from spring to neap. Discharge synchronizes with water level and the time scale of its information transfer compares well to physical travel times through the system, computed with a hydrodynamic model. Information transfer and physical transport show similar spatial patterns, although information transfer time scales are larger than physical travel times. Wind events associated with water level setup lead to increased process connectivity with highly variable information transfer time scales. We discuss the information theory results in the context of the hydrologic behavior of the delta, the role of vegetation as a connector/disconnector on islands, and the applicability of process networks as tools for delta modeling results.
Using SAS functions and high‐resolution isotope data to unravel travel time distributions in headwater catchments
Authors: Benettin Paolo , Soulsby Chris , Birkel Christian , Tetzlaff Doerthe , Botter Gianluca , Rinaldo Andrea 
Published: February 2017

AbstractWe use high‐resolution tracer data from an experimental site to test theoretical approaches that integrate catchment‐scale flow and transport processes in a unified framework centered on selective age sampling by streamflow and evapotranspiration fluxes. Transport processes operating at the catchment scale are reflected in the evolving residence time distribution of the catchment water storage and in the age selection operated by out‐fluxes. Such processes are described here through StorAge Selection (SAS) functions parameterized as power laws of the normalized rank storage. Such functions are computed through appropriate solution of the master equation defining formally the evolution of residence and travel times. By representing the way in which catchment storage generates outflows composed by water of different ages, the main mechanism regulating the tracer composition of runoff is clearly identified and detailed comparison with empirical data sets are possible. Properly calibrated numerical tools provide simulations that convincingly reproduce complex measured signals of daily deuterium content in stream waters during wet and dry periods. Results for the catchment under consideration are consistent with other recent studies indicating a tendency for natural catchments to preferentially release younger available water. The study shows that power law SAS functions prove a powerful tool to explain catchment‐scale transport processes that also has potential in less intensively monitored sites.
Understanding feedbacks between ocean acidification and coral reef metabolism
Authors: Takeshita Yuichiro 
Published: February 2017

AbstractBiogeochemical feedbacks from benthic metabolism have been hypothesized as a potential mechanism to buffer some effects of ocean acidification on coral reefs. The article in JGR‐Oceans by DeCarlo et al. demonstrates the importance of benthic community health on this feedback from Dongsha Atoll in the South China Sea.
Mentoring as a Mediator or Moderator of the Association between Racial Discrimination and Coping Efficacy in Urban, Low‐Income Latina/o Youth
Authors: Sánchez Bernadette , Mroczkowski Alison L. , Liao Lynn C. , Cooper Adina C. , Rivera Claudio , DuBois David L. 
Published: February 2017

AbstractThe aim of this study was to examine the associations among mentoring relationship quality (i.e., relational and instrumental quality), racial discrimination and coping efficacy with racial discrimination. Three social support models were tested, including the stress buffering, support mobilization, and support deterioration models. Participants were 257 urban, low‐income Latina/o high school students, who completed surveys in both 9th and 10th grades. While controlling for gender and coping efficacy with discrimination in 9th grade, results supported the social support deterioration model. Specifically, there was a significant indirect effect of racial discrimination in 9th grade on coping efficacy in 10th grade through instrumental mentoring quality. As racial discrimination increased, mentoring quality decreased and then coping efficacy decreased. We also found that more racial discrimination in 9th grade was significantly associated with lower coping efficacy in 10th grade, and higher instrumental mentoring quality in 9th grade was significantly associated with higher coping efficacy in 10th grade, while controlling for gender and coping efficacy in 9th grade. Implications and recommendations for future research are discussed.
Facile preparation of ODPA‐ODA type polyetherimide‐based carbon membranes by chemical crosslinking
Authors: Zhang Xiaoyu , Zhang Bing , Wu Yonghong , Wang Dan , Wang Tonghua 
Published: February 2017

ABSTRACTA chemical crosslinking protocol was developed to prepare carbon membranes from 3,3′,4,4′‐oxydiphthalic dianhydride‐4,4′‐oxydianiline (ODPA–ODA) type polyetherimide on the support of phenolic resin sheets. The effects of support pretreatment, membrane‐coating methods and crosslinking protocols on the resultant carbon membranes were investigated. The microstructure, functional group evolution, thermal stability, mechanics, morphology, and gas separation performance of samples were characterized by XRD, FTIR, TGA, mechanical testing technique, and gas permeation technique, respectively. Results have shown that the chemical crosslinking is more beneficial than the popular thermal crosslinking protocol to fabricate supported carbon membranes for the advantage of simple preparation process. In addition, spin‐coating is superior to drop‐coating in terms of good membrane formation on the support. Under the preferred preparation conditions of crosslinker ethylene glycol usage at 10 wt % and spin‐coating, supported carbon membranes can be obtained with good hydrogen separation performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44889.
Preparation of cardanol based epoxy plasticizer by click chemistry and its action on poly(vinyl chloride)
Authors: Yao Leilei , Chen Qinhui , Xu Wenqin , Ye Zhibin , Shen Zhaodi , Chen Meijin 
Published: February 2017

ABSTRACTIn recent years, the using of reproducible resource and economical and efficient synthesis method has got wide concern. Herein, an environmental‐friendly plasticizer originated from cardanol was synthesized by click chemistry. First, the cardanol sulfide (CS) was obtained by click chemistry reaction between the double bond of the side chain of cardanol and mercaptoethanol. The degree of the click reaction was estimated to reach 84.7% by testing the content of sulfur. Then, the epoxidation of the hydroxyl was performed to get cardanol based epoxy plasticizer (CEP) in the presence of epichlorohydrin. The epoxy value was 0.32. The structure of CS and CEP was confirmed by FT‐IR and NMR techniques. A Haake torque rheometer was used to research the action of CEP on polyvinyl chloride (PVC). Results showed that it possessed favorable plasticization effect and stabilization effect on PVC. CEP had good heat stabilization in PVC, and could decrease the Tg of PVC significantly. Moreover, CEP could increase the tensile strength of PVC when in a small amount, and could increase the plasticity of PVC when in a larger quantity significantly. The characteristics of volatile, migration and solvent extraction of PVC plasticized by CEP is similar to by dioctyl phthalate (DOP). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44890.
Consolidation by spark plasma sintering (SPS) of polyetheretherketone
Authors: Sébileau Jean‐Charles , Lemonnier Sébastien , Barraud Elodie , Vallat Marie‐France , Carradò Adele , Nardin Michel 
Published: February 2017

ABSTRACTThe present study deals with the consolidation of an ultra‐high performance polymer, the poly(ether ether ketone) (PEEK), for structural applications, using the powder metallurgy (PM) way, and more precisely the Spark Plasma Sintering (SPS) processing. The effects of SPS parameters such as temperature, pressure, and dwell time on density and mechanical properties of PEEK were investigated via a Design of Experiments (DoE). A temperature of 250 °C, a pressure of 40 MPa, and a dwell time of 20 min have been identified as the optimal SPS process parameters. In these conditions, a density of 1.31 g/cm3 was reached and homogeneous mechanical properties in the volume determined by means of compression tests were found with a compressive modulus of 2.75 GPa, a yield strength of 134 MPa, and a maximum compressive strain of 43%. These results are better than those of commercial products obtained by injection molding. The pressure appears to be a significant parameter on PEEK properties and plays positive or negative roles according to the responses of DoE studied. To our knowledge, it is one of the first studies based on the application of the PM techniques for PEEK consolidation showing the possibility to process below its melting point. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44911.
Surface ammonification of the mutual‐irradiated aramid fibers in 1,4‐dichlorobutane for improving interfacial properties with epoxy resin
Authors: Xie Fei , Xing Lixin , Liu Li , Liu Yuguang , Zhong Zhengxiang , Jia Chuyuan , Wang Wei , Wang Caifeng , Zhao Min , Huang Yudong 
Published: February 2017

ABSTRACTThe mutual irradiated aramid fibers in 1,4‐dichlorobutane was ammoniated by ammonia/alcohol solution, in an attempt to improve the interfacial properties between aramid fibers and epoxy matrix. Scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), dynamic contact angle analysis (DCA), interfacial shear strength (IFSS), and single fiber tensile testing were carried out to investigate the functionalization process of aramid fibers and the interfacial properties of the composites. Experimental results showed that the fiber surface elements content changed obviously as well as the roughness through the radiation and chemical reaction. The surface energy and IFSS of aramid fibers increased distinctly after the ammonification, respectively. The amino groups generated by ammonification enhanced the interfacial adhesion of composites effectively by participating in the epoxy resin curing. Moreover, benefited by the appropriate radiation, the tensile strength of aramid fibers was not affected at all. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44924.
Improving the UV resistance of aromatic poly(1,3,4‐oxadiazole) fiber using the disperse dye modified with octavinyl POSS. Part 2: Fixing form of dye and UV resistance ability
Authors: Mao Yahong , Zheng Xiong , Guan Yu 
Published: February 2017

ABSTRACTDisperse Red 60 modified with octavinyl polyhedral oligomeric silsesquioxanes (POSS) was used to color poly(p‐phenylene‐1,3,4‐oxadiazoles) (p‐POD) fiber. The dyed p‐POD fiber was given high UV resistance and excellent color strength (K/S value) simultaneously. And the effects of the UV irradiation time on the K/S values and the strength retention of dyed fiber were investigated. The results indicated that the modified dye (1:3) molecules can easily be adsorbed on fiber surface and diffuse into fiber, whose fixing form on the fiber surface is a semiembedded type. Meanwhile, the surface morphology, the aggregation structure, the thermal property, the color fastness, and anti‐UV durability of the dyed p‐POD fiber were characterized. After UV accelerated aging, the macroscopic and microscopic structures of the dyed p‐POD fiber can well be maintained and the color fastness is also satisfactory. Meanwhile, this method also solves the problem of poor anti‐UV durability of the modified fiber with the previous processes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44928.
The combination of expandable graphite, organic montmorillonite, and magnesium hydrate as fire‐retardant additives for ethylene–propylene–diene monomer/chloroprene rubber foams
Authors: Ding Zhengmao , Li Yingchun , He Maoyong , Wang Wensheng , Wang Chao 
Published: February 2017

ABSTRACTThe fire retardancy and flame‐retardant mechanism of expandable graphite (EG), organic montmorillonite (OMMT), and magnesium hydrate (MH) in ethylene‐propylene‐diene monomer/chloroprene rubber (EPDM/CR) foams were investigated. The results indicated that the combination of EG and OMMT remarkably improved the fire‐retardant property compared to the control samples, and better fireproof performance was achieved when MH was used as the third coretardant unit. The structure of the obtained EPDM/CR/OMMT composites was characterized by X‐ray diffraction, and the results showed that the composites had an intercalated nanostructure. The limiting oxygen index, vertical burning test, and cone calorimeter test results showed that the LOI values and UL‐94 rating increased while the second peak of the heat release rates (HRR) decreased within the EG/OMMT system. In particular, the second pHRR disappeared when the EG/OMMT/MH system was used as a flame retardant. Moreover, the results of thermogravimetric analysis showed that the combination of EG and OMMT reduced the thermal‐degradation rates and mass‐loss percentages. Furthermore, observation by scanning electron microscopy revealed that EG and OMMT left over after combustion formed a complete, compact, and rigid charred layer with a mosaic structure of expanded graphite embedded in cortical‐honeycomb layers of OMMT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44929.
Enhanced electroactive β phase in three phase PVDF/CaCO3/nanoclay composites: Effect of micro‐CaCO3 and uniaxial stretching
Authors: Jahan Nusrat , Mighri Frej , Rodrigue Denis , Ajji Abdellah 
Published: February 2017

ABSTRACTIn this study, electroactive polar phase transformation and crystallinity of poly(vinylidene fluoride) (PVDF)‐based composites, such as PVDF/CaCO3/nanoclay, is explored as a function of micro‐CaCO3 fraction and draw ratio (R) of uniaxial stretching. Composites including PVDF/clay, PVDF/CaCO3 and most importantly PVDF/CaCO3/clay with varying fraction of micro‐CaCO3 were extruded into homogenous and flexible cast films. Characterization via Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry (DSC) confirmed the presence of β phase in all the composites incorporated with micro‐CaCO3 and nanoclay either individually (i.e., PVDF/CaCO3 and PVDF/clay films, respectively) or together (i.e., PVDF/CaCO3/nanoclay composites). Interestingly, a gradual but significant improvement in this electroactive phase (β phase) was obtained with successive increment in CaCO3 content into a fixed composition of PVDF and nanoclay (PVDF/CaCO3/clay composites). Further increment in β phase content was obtained via uniaxial stretching to different draw ratios and at a temperature of 90 °C, where for PVDF/CaCO3/clay (especially, 100–35‐3 and 100–40‐3) samples almost no α phase was observed irrespective of R. Conversely, the crystallinity of melt extruded samples decreased gradually all the way with CaCO3 concentration in PVDF/CaCO3/clay composites compared to the neat PVDF while increased gradually with increasing draw ratio. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44940.
Control of chitin nanofiber production by the lipid‐producing diatom Cyclotella Sp. through fed‐batch addition of dissolved silicon and nitrate in a bubble‐column photobioreactor
Authors: Chiriboga N. Omar G. , Rorrer Gregory L. 
Published: February 2017

Diatoms are single‐celled algae that make cell walls of nanopatterned biogenic silica called frustules through metabolic uptake of dissolved silicon and its templated condensation into biosilica. The centric marine diatom Cyclotella sp. also produces intracellular lipids and the valued coproduct chitin, an N‐acetyl glucosamine biopolymer that is extruded from selected frustule pores as pure nanofibers. The goal of this study was to develop a nutrient feeding strategy to control the production of chitin nanofibers from Cyclotella with the coproduction of biofuel lipids. A two‐stage phototrophic cultivation process was developed where Stage I set the cell suspension to a silicon‐starved state under batch operation, and Stage II continuously added silicon and nitrate to the silicon‐starved cells to enable one more cell doubling to 4 × 106 cells mL−1. The silicon delivery rate was set to enable a silicon‐limited cell division rate under cumulative delivery of 0.8 mM Si and 1.2 mM nitrate (1.5:1 mol N/mol Si) over a 4‐ to 14‐day addition period. In Stage II, both cell number and chitin production were linear with time. Cell number and the specific chitin production rate increased linearly with increasing silicon delivery rate to achieve cumulative product yields of 13 ± 1 mg chitin/109 cells and 33 ± 3 mg lipid/109 cells. Therefore, chitin production is controlled through cell division, which is externally controlled through silicon delivery. Lipid production was not linearly correlated to silicon delivery and occurred primarily during Stage I, just after the complete co‐consumption of both dissolved silicon and nitrate. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:407–415, 2017