bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atmospheric photochemical reactivity and ozone production at two sites in Hong Kong: Application of a Master Chemical Mechanism–photochemical box model
Authors: Ling Z. H. , Guo H. , Lam S. H. M. , Saunders S. M. , Wang T. 
Published: August 2014

AbstractA photochemical box model incorporating the Master Chemical Mechanism (v3.2), constrained with a full suite of measurements, was developed to investigate the photochemical reactivity of volatile organic compounds at a semirural site (Mount Tai Mo Shan (TMS)) and an urban site (Tsuen Wan (TW)) in Hong Kong. The levels of ozone (O3) and its precursors, and the magnitudes of the reactivity of O3 precursors, revealed significant differences in the photochemistry at the two sites. Simulated peak hydroperoxyl radical (HO2) mixing ratios were similar at TW and TMS (p = 0.05), while the simulated hydroxyl radical (OH) mixing ratios were much higher at TW (p < 0.05), suggesting different cycling processes between OH and HO2 at the two sites. The higher OH at TW was due to high‐NO mixing ratios, which shifted the HOx (OH + HO2) balance toward OH by the propagation of HO2 and alkyl peroxy radicals (RO2) with NO. HOx production was dominated by O3 photolysis at TMS, but at TW, both HCHO and O3 photolyses were found to be major contributors. By contrast, radical‐radical reactions governed HOx radical losses at TMS, while at TW, the OH + NO2 reaction was found to dominate in the morning and the radical‐radical reactions at noon. Overall, the conversion of NO to NO2 by HO2 dictated the O3 production at the two sites, while O3 destruction was dominated by the OH + NO2 reaction at TW, and at TMS, O3 photolysis and the O3 + HO2 reaction were the major mechanisms. The longer OH chain length at TMS indicated that more O3 was produced for each radical that was generated at this site.
Exner‐Based Master Equation for transport and dispersion of river pebble tracers: Derivation, asymptotic forms, and quantification of nonlocal vertical dispersion
Authors: Pelosi A. , Parker G. , Schumer R. , Ma H.‐B. 
Published: August 2014

AbstractIdeas deriving from the standard formulation for continuous time random walk (CTRW) based on the Montroll‐Weiss Master Equation (ME) have been recently applied to transport and diffusion of river tracer pebbles. CTRW, accompanied by appropriate probability density functions (PDFs) for walker step length and waiting time, yields asymptotically the standard advection‐diffusion equation (ADE) for thin‐tailed PDFs and the fractional advection‐diffusion equation (fADE) for heavy‐tailed PDFs, the latter allowing the possibilities of subdiffusion or superdiffusion. Here we show that the CTRW ME is inappropriate for river pebbles moving as bed load: a deposited particle raises local bed elevation, and an entrained particle lowers it so that particles interact with the “lattice” of the sediment‐water interface. We use the Parker‐Paola‐Leclair framework, which is a probabilistic formulation of the Exner equation of sediment conservation, to develop a new ME for tracer transport and dispersion for alluvial morphodynamics. The formulation is based on the existence of a mean bed elevation averaged over fluctuations. The new ME yields asymptotic forms for ADE and fADE that differ significantly from CTRW. It allows vertical as well as streamwise advection‐diffusion. Vertical dispersion is nonlocal but cannot be expressed with fractional derivatives. In order to illustrate the new model, we apply it to the restricted case of vertical dispersion only, with both thin and heavy tails for relevant PDFs. Vertical dispersion shows a subdiffusive behavior.
Inversion of fluvial channels for paleorock uplift rates in Taiwan
Authors: Fox Matthew , Goren Liran , May Dave A. , Willett Sean D. 
Published: August 2014

AbstractThe transient response of erosion to changes in rock uplift rate leads to the preservation of rock uplift history in the long profiles of rivers. However, extracting this information is nontrivial as changes in channel steepness are the result of both spatial and temporal changes in rock uplift rate, as well as other factors such as climate and rock type. We exploit an analytical linear solution for river channel profile evolution in response to erosion and tectonic uplift to investigate the rock uplift history of Taiwan. The analytical approach allows us to solve the linear inverse problem, efficiently extracting rock uplift as a function of space and time, from digital elevation data. We assess the potential of fluvial topography to resolve rock uplift rates using three approaches: (1) a synthetic resolution test, (2) analysis of the forward model to demonstrate where in space and time the fluvial topography constrains rock uplift rate, and (3) interpretation of the model resolution matrix. Furthermore, the potential to analyze large data sets reduces the influence of stochastic processes such as landslides, small‐scale river network reorganization, and also local lithological variability. In Taiwan, our analysis suggests that current rock uplift rates exceed erosion rates across much of the island and that there has been an increase in rock uplift rates since 0.5 Ma across the Central Range.
A 3‐D thermal regime model suitable for cold accumulation zones of polythermal mountain glaciers
Authors: Gilbert A. , Gagliardini O. , Vincent C. , Wagnon P. 
Published: August 2014

AbstractAnalysis of the thermal and mechanical response of high altitude glaciers to climate change is crucial to assess future glacier hazards associated with thermal regime changes. This paper presents a new fully thermo‐mechanically coupled transient thermal regime model including enthalpy transport, firn densification, full‐Stokes porous flow, free surface evolution, strain heating, surface meltwater percolation, and refreezing. The model is forced by daily air temperature data and can therefore be used to perform prognostic simulations for different future climate scenarios. The set of equations is solved using the finite element ice sheet/ice flow model Elmer/Ice. This model is applied to the Col du Dôme glacier (Mont Blanc area, 4250 m a.s.l., France) where a comprehensive data set is available. The results show that the model is capable of reproducing observed density and velocity fields as well as borehole temperature evolution. The strong spatial variability of englacial temperature change observed at Col du Dôme is well reproduced. This spatial variability is mainly a result of the variability of the slope aspect of the glacier surface and snow accumulation. Results support the use of this model to study the influence of climate change on cold accumulation zones, in particular to estimate where and under what conditions glaciers will become temperate in the future.
Beyond optimality: Multistakeholder robustness tradeoffs for regional water portfolio planning under deep uncertainty
Authors: Herman Jonathan D. , Zeff Harrison B. , Reed Patrick M. , Characklis Gregory W. 
Published: August 2014

AbstractWhile optimality is a foundational mathematical concept in water resources planning and management, “optimal” solutions may be vulnerable to failure if deeply uncertain future conditions deviate from those assumed during optimization. These vulnerabilities may produce severely asymmetric impacts across a region, making it vital to evaluate the robustness of management strategies as well as their impacts for regional stakeholders. In this study, we contribute a multistakeholder many‐objective robust decision making (MORDM) framework that blends many‐objective search and uncertainty analysis tools to discover key tradeoffs between water supply alternatives and their robustness to deep uncertainties (e.g., population pressures, climate change, and financial risks). The proposed framework is demonstrated for four interconnected water utilities representing major stakeholders in the “Research Triangle” region of North Carolina, U.S. The utilities supply well over one million customers and have the ability to collectively manage drought via transfer agreements and shared infrastructure. We show that water portfolios for this region that compose optimal tradeoffs (i.e., Pareto‐approximate solutions) under expected future conditions may suffer significantly degraded performance with only modest changes in deeply uncertain hydrologic and economic factors. We then use the Patient Rule Induction Method (PRIM) to identify which uncertain factors drive the individual and collective vulnerabilities for the four cooperating utilities. Our framework identifies key stakeholder dependencies and robustness tradeoffs associated with cooperative regional planning, which are critical to understanding the tensions between individual versus regional water supply goals. Cooperative demand management was found to be the key factor controlling the robustness of regional water supply planning, dominating other hydroclimatic and economic uncertainties through the 2025 planning horizon. Results suggest that a modest reduction in the projected rate of demand growth (from approximately 3% per year to 2.4%) will substantially improve the utilities' robustness to future uncertainty and reduce the potential for regional tensions. The proposed multistakeholder MORDM framework offers critical insights into the risks and challenges posed by rising water demands and hydrological uncertainties, providing a planning template for regions now forced to confront rapidly evolving water scarcity risks.
An intercomparison of statistical downscaling methods used for water resource assessments in the United States
Authors: Gutmann Ethan , Pruitt Tom , Clark Martyn P. , Brekke Levi , Arnold Jeffrey R. , Raff David A. , Rasmussen Roy M. 
Published: August 2014

AbstractInformation relevant for most hydrologic applications cannot be obtained directly from the native‐scale outputs of climate models. As a result the climate model output must be downscaled, often using statistical methods. The plethora of statistical downscaling methods requires end‐users to make a selection. This work is intended to provide end‐users with aid in making an informed selection. We assess four commonly used statistical downscaling methods: daily and monthly disaggregated‐to‐daily Bias Corrected Spatial Disaggregation (BCSDd, BCSDm), Asynchronous Regression (AR), and Bias Corrected Constructed Analog (BCCA) as applied to a continental‐scale domain and a regional domain (BCCAr). These methods are applied to the NCEP/NCAR Reanalysis, as a surrogate for a climate model, to downscale precipitation to a 12 km gridded observation data set. Skill is evaluated by comparing precipitation at daily, monthly, and annual temporal resolutions at individual grid cells and at aggregated scales. BCSDd and the BCCA methods overestimate wet day fraction, and underestimate extreme events. The AR method reproduces extreme events and wet day fraction well at the grid‐cell scale, but over (under) estimates extreme events (wet day fraction) at aggregated scales. BCSDm reproduces extreme events and wet day fractions well at all space and time scales, but is limited to rescaling current weather patterns. In addition, we analyze the choice of calibration data set by looking at both a 12 km and a 6 km observational data set; the 6 km observed data set has more wet days and smaller extreme events than the 12 km product, the opposite of expected scaling.
A Comparative Study on Humidity Sensing Performances of Polyaniline and Polypyrrole Nanostructures
Authors: Joulazadeh Mehrnaz , Navarchian Amir H. , Niroomand Mehdi 
Published: August 2014

ABSTRACTThis paper addresses the preparation of polyaniline (PAni) and polypyrrole (PPy) nanostructures as humidity sensor elements. The semicrystalline microstructure and chemical structure of synthesized PAni and PPy were studied by X‐ray diffraction and Fourier transform infrared spectroscopy, respectively. The morphology of these polymers was studied by scanning electron microscopy and transmission electron microscopy, indicating fibrillar and tubular nanostructures for PAni and PPy, respectively. The humidity sensing performances of sensors based on the prepared nanostructural PAni and PPy were investigated, and the sensing mechanisms of both systems have been discussed. The interesting reverse behaviors during humidity exposure of PAni‐ and PPy‐based sensors in different water vapor concentrations have been comprehensively justified. The temperature dependency of the electrical conductivity for PAni and PPy samples was investigated. The UV–vis spectroscopy was used to study the effect of moisture on the electronic transport properties of PAni and PPy nanostructures.
High thermal conductive m‐xylylenediamine functionalized multiwall carbon nanotubes/epoxy resin composites
Authors: Xie Fan , Qi Shuhua , Yang Rui , Wu Dong 
Published: August 2014

ABSTRACTIn this study, multiwall carbon nanotubes (MWNTs) functionalized by m‐xylylenediamine is used as thermal conductive fillers to improve their dispersibility in epoxy resin and the thermal conductivity of the MWNTs/bisphenol‐A glycidol ether epoxy resin composites. Functionalization with amine groups of MWNTs is achieved after such steps as carboxylation, acylation and amidation. The thermal conductivity, impact strength, flexural strength, and fracture surfaces of MWNTs/epoxy composites are investigated with different MWNTs. The results show that m‐xylylenediamine is successfully grafted onto the surface of the MWNTs and the mass fraction of the organic molecules grafted onto MWNTs is about 20 wt %. The thermal conductivity of MWNTs/epoxy composites is further enhanced to 1.236 W/mK with 2 wt % m‐MWNTs. When the content of m‐MWNTs is 1.5 wt %, the impact strength and flexural strength of the composites are 25.85 KJ/m2, 128.1 MPa, respectively. Scanning electron microscope (SEM) results show that the fracture pattern of composites is changed from brittle fracture to ductile fracture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41255.
Monitoring production process of cisplatin‐loaded PLGA nanoparticles by FT‐IR microspectroscopy and univariate data analysis
Authors: Portaccio Marianna , Menale Ciro , Diano Nadia , Serri Carla , Mita Damiano G. , Lepore Maria 
Published: August 2014

ABSTRACTCisplatin‐loaded PLGA nanoparticles for drug delivery have been prepared using a well‐established water/oil/water double emulsion‐solvent evaporation method. The production process has been monitored by using Fourier Transform Infrared (FT‐IR) microspectroscopy without using KBr tablets and any preliminary sample preparation. Significant spectra have been obtained for all chemical compounds and for samples at different steps of production process. The use of a linear or univariate approach using a R2 determination coefficient has been proposed for discriminating among FT‐IR spectra even when small differences are present. The obtained results confirm that new geometries of data acquisition contribute to make infrared microspectroscopy a very useful tool for a rapid and detailed monitoring of production processes of pharmacological interest. Moreover, morphological and physiological characterizations have been performed on cisplatin‐loded samples showing results in good agreement with those reported in literature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41305.
Modification of polysulfones by click chemistry: Zwitterionic graft complex and their antiprotein fouling property
Authors: Xu Canhong , Gu Shaojin , Huang Jingjing , Xu Weilin , Xia Huan , Du Jiehao , Liu Hongtao , Yang Hongjun , Zhou Yingshan , Bai Zikui 
Published: August 2014

ABSTRACTA new nonspecific protein antifouling polysulfone (PSU) material has been elaborated by grafting zwitterionic sulfobetaine (SB) complex by the means of PSU azidation (PSU‐N3) followed by “Click‐Chemistry” with acetylenic zwitterionic SB monomer (N,N'‐diethyl‐N‐propargyl‐N‐ (3‐sulfopropyl) ammonium (DEPAS)). Azidation (PSU‐N3) and functionalization (PSU‐g‐DEPAS) PSU materials were characterized by 1H NMR, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Contact angle and protein adsorption on PSU‐g‐DEPAS and unmodified PSU membrane were studied. The results show that the chemical modification of PSU improved both the hydrophilicity and antiprotein absorption ability. This new fouling‐resistance to protein material has potential for biomaterials applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41327.
Electrospray preparation of propranolol‐loaded alginate beads: Effect of matrix reinforcement on loading and release profile
Authors: Khorram Mohammad , Samimi Mohsen , Samimi Abdolreza , Moghadam Hamid 
Published: August 2014

ABSTRACTIn the present study, propranolol loaded‐calcium alginate beads were prepared from concentrated solutions of sodium alginate, using combined method of electrospray and ionotropic gelation. The objectives of the study were to increase the propranolol‐HCl loading and to decrease its initial burst release. However, the effects of voltage, nozzle diameter, flow rate, and concentration of sodium alginate on size of the beads and drug entrapment efficiency (DEE) were also investigated. The matrix of alginate beads was reinforced with dextran sulfate and/or coated with chitosan. The mean particle size of the beads, their swelling behavior, and drug entrapment efficiency were characterized. Furthermore, the drug release profiles from the prepared beads in simulated gastric fluid and intestinal fluid were evaluated and compared. Among the parameters that affected the electrospray of alginate, voltage had a pronounced effect on the size of beads. The size of beads was reduced to a minimum value on increasing the voltage. Furthermore, increasing the flow rate, alginate concentration, and nozzle diameter and decreasing the voltage led to improvement in DEE. Enhancing the alginate concentration as well as coating with chitosan and reinforcing with dextran sulfate led to increase of the encapsulation efficiency and therefore decrease of the drug release rate in both pHs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41334.
Polypyrrole‐silk electro‐conductive composite fabric byin situchemical polymerization
Authors: Malhotra Urvashi , Maity Subhankar , Chatterjee Arobindo 
Published: August 2014

ABSTRACTThis article describes the preparation of polypyrrole‐silk composite fabric byin situchemical polymerization of pyrrole.In situpolymerization process has been optimized by employing Box‐Behnken response surface design. The effect of process parameters on surface resistivity of the fabric has been statistically analyzed. Most significant process parameter and interaction effects have been identified. Thermal, electrical, and morphological properties of the composite fabric have been studied. Surface resistivity of the fabric obtained is 636.33 Ω. The fabric composite shows a linerV–Icharacteristic like an Ohmic conductor. An exponential rise of surface temperature of the fabric is observed by the application of DC voltage across it. Optical microscopic and SEM studies reveal uniform and even coating of polypyrrole on silk surface. FTIR studies indicate a possible chemical interaction between polypyrrole and silk. The polypyrrole‐treated composite fabric exhibits enhanced thermal stability as is evidenced from DSC and TGA result. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 41336.
Rheology, morphology, and mechanical properties of HMSPP/POE blends and its alternate layered foam
Authors: Zhao Tianbao , Zhang Xianlong , Wu Hong , Guo Shaoyun , Sun Xiaojie , Liang Wenbin 
Published: August 2014

ABSTRACTIn this article, the multilayered foaming sheet with alternate layered structure was successfully prepared through multilayer co‐extrusion. The high melt strength polypropylene (HMSPP)/poly (ethylene‐co‐octene) (POE) blend and POE were designed as foaming layers and film layers, respectively. POE was added into HMSPP to reduce the crystalline degree and improve the processing performance. The rheological results indicated that the addition of POE had a little effect on relaxation process and the strain hardening behavior of HMSPP when the POE content was lower than 50%. The results of the foam morphology showed that the cell size and its distribution of the multilayered foaming sheet with alternate layers were better than that with single layer. In addition, the cell size reduced and the cell density increased with increasing the number of layers from 4 to 32. The mechanical properties of the multilayered foaming sheet with alternate layers also could be improved through assembling of foaming layers and film layers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41339.
Residual charge and filtration efficiency of polycarbonate fibrous membranes prepared by electrospinning
Authors: Cho Byoung Min , Nam Young Sik , Cheon Ja Young , Park Won Ho 
Published: August 2014

ABSTRACTPolycarbonate (PC) ultrafine fiber membranes with benzyl triethylammonium chloride (BTEAC) were prepared by electrospinning of PC/chloroform solution with different BTEAC contents. In the presence of BTEAC additive, the PC solution showed a better electrospinnability and led to thinner fibers with uniformity than the neat PC solution. The charge retention of the electrospun PC fibrous membranes with BTEAC was investigated in terms of additive content, membrane thickness and storage condition. The residual charge on the PC fibrous membrane was increased to 1 wt % BTEAC content, but thereafter gradually decreased up to 10 wt % BTEAC. In addition, the residual charge on the membrane was increased with increasing the membrane thickness, but was rapidly decreased at a high humidity condition in comparison with a low humidity. The filtration efficiency was examined for the fibrous membranes with or without BTEAC. The PC membrane with BTEAC had higher filtration efficiency than one without BTEAC, not affecting the pressure drop. The filtration efficiency between the PC membranes with or without residual charge was also compared. When the residual charge existed on the membrane, the membrane showed higher filter efficiency because of the enhanced filtration effect by an electrostatic attraction. Therefore, the PC fibrous membranes with BTEAC have a great potential as an electrets filter for air filtration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41340.
Effect of surfactant on EG dispersion in EVA and thermal and mechanical properties of the system
Authors: Sefadi Shale J. , Luyt Adriaan S. , Pionteck Jürgen 
Published: August 2014

ABSTRACTThe influence of expanded graphite (EG) and sodium dodecyl sulfate (SDS) modified EG on the structure, thermal stability, and mechanical properties of ethylene vinyl acetate (EVA) was investigated in this study. The EVA filled with EG platelets, with and without anionic SDS modification, was prepared by melt mixing using a Brabender Plastograph mixer. The extent of dispersion and morphology of the composites were characterized using scanning electron microscopy (SEM), optical microscopy (OM), and X‐ray diffraction (XRD). The optical microscopy results show better distribution of the modified EG platelets in the EVA matrix, while the SEM results show an improved interfacial adhesion between the polymer and the SDS‐EG particles. Both the EVA18 copolymer and the EG platelets have monoclinic phases, and both EG and SDS do not seem to have any influence on the melting and crystallization behavior of the EVA18. The addition of EG enhanced the thermal stability of EVA18, and this stabilizing influence was further improved when the EG was treated with SDS. All the tensile properties of EVA/EG improved after surface modification. The storage modulus of EVA generally increased with increasing both the unmodified EG and the SDS modified EG content. There was a shift in the Tg to higher temperatures with an increase in both the EG and modified EG content. The α‐relaxation peak in the SDS modified EG curves was less intense than the β‐relaxation peak, even for the untreated EG composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41352.