bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acrylic bone cements modified with poly(ethylene glycol)‐based biocompatible phase‐change materials
Authors: Król Klaudia , Macherzyńska Beata , Pielichowska Kinga 
Published: June 2016

ABSTRACTThe high polymerization temperature of acrylic bone cements used in hip replacement implantation may cause thermal necrosis of surrounding tissues. In order to reduce the polymerization temperature, acrylic bone cement has been modified with a biocompatible polymeric phase‐change material (PCM) based on poly(ethylene glycol) (PEG) of different molecular weights and stabilized with potato starch. Structural and morphological studies were performed, and the thermal and mechanical properties were investigated. The incorporation of PEG‐based PCM led to a decrease in the polymerization temperature of bone cement from 70 °C for unmodified cement to 58 °C for modified cement. Modified cement materials were stable in incubation tests, although acoustic analysis data revealed a decrease in propagation speed after incubation, which indicates formation of material defects (pores, cracks, voids, etc.) due to water activity. However, in the regeneration process, these defects can be filled by freshly grown bone tissue leading to better incorporation of bone cement replacements into tissue. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43898.
Flame‐retardant properties and mechanisms of epoxy thermosets modified with two phosphorus‐containing phenolic amines
Authors: Wang Peng , Yang Fusheng , Li Liang , Cai Zaisheng 
Published: June 2016

ABSTRACTTwo phosphorus‐containing phenolic amines, a 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based derivative (DAP) by covalently bonding DOPO and imine (SB) obtained from the condensation of p‐phenylenediamine with salicylaldehyde, and its analog (AP) via the addition reaction between diethyl phosphite and SB, were used to prepare flame‐retardant epoxy resins. The burning behaviors and dynamic mechanical properties of epoxy thermosets were studied by limited oxygen index (LOI) measurement, UL‐94 test, and dynamic mechanical analysis. The flame‐retardant mechanisms of modified thermosets were investigated by thermogravimetric analysis, Py‐GC/MS, Fourier transform infrared, SEM, elemental analysis, and laser Raman spectroscopy. The results revealed that epoxy thermoset modified with DAP displayed the blowing‐out effect during UL‐94 test. With the incorporation of 10 wt % DAP, the modified thermoset showed an LOI value of 36.1% and V‐0 rating in UL‐94 test. The flame‐retardant mechanism was ascribed to the quenching and diluting effect in the gas phase and the formation of phosphorus‐rich char layers in the condensed phase. However, the thermoset modified with 10 wt % AP only showed an LOI value of 25.7% and no rating in UL‐94 test, which was possibly ascribed to the mismatching of charring process with gas emission process during combustion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43953.
Morphology and mechanical properties of natural rubber latex films modified by exfoliated Na‐montmorillonite/polyethyleneimine‐g‐poly (methyl methacrylate) nanocomposites
Authors: Wang Shuyi , Tian Xiaohui , Sun Jinyu , Liu Jin , Duan Junchao 
Published: June 2016

ABSTRACTNa‐montmorillonite/polyethyleneimine‐g‐poly(methyl methacrylate) (Na‐MMT/PEI‐g‐PMMA) nanocomposite latexes were prepared by soap‐free emulsion polymerization in the aqueous suspension of Na‐MMT. The exfoliated morphology of the nanocomposites was confirmed by XRD and TEM. With the aim of improving morphology and mechanical properties of natural rubber latex (NRL) films, the synthesized Na‐MMT/PEI‐g‐PMMA nanocomposites were mixed with NRL by latex compounding technology. The results of SEM and AFM analysis showed that the surface of NRL/Na‐MMT/PEI‐g‐PMMA film was smoother and denser than that of pristine NRL film while Na‐MMT was dispersed uniformly on the fracture surface of the modified films, which suggested the good compatibility between NRL and Na‐MMT/PEI‐g‐PMMA. The tensile strength of NRL/Na‐MMT/PEI‐g‐PMMA films was increased greatly by 85% with 10 phr Na‐MMT/PEI‐g‐PMMA when Na‐MMT content was 3 wt % and the elongation at break also increased from 930% to 1073% at the same time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43961.
Numerical investigation of spinneret geometric effect on spinning dynamics of dry‐jet wet‐spinning of cellulose/[BMIM]Cl solution
Authors: Xia Xiaolin , Wang Jianning , Wang Huaping , Zhang Yumei 
Published: June 2016

ABSTRACTIn this study, the effect of spinneret geometry, including the entrance angle α of the entrance channel, the length Ls, and the diameter D0 of the exit channel, on the spinning dynamics of dry‐jet wet‐spinning of cellulose/1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) solution was simulated by using finite element method. Based on the mathematical model of dry‐jet wet‐spinning established in our previous work (Xia et al., Cellulose 2015, 22, 1963) the radial and axial profiles of velocity, pressure, and shear rate in the spinneret and the profiles of diameter, temperature, and tensile stress in the air‐gap region were obtained. From the simulated profiles, the effect of spinneret geometric parameters on the flow behavior and the pressure drop of polymer solution in the spinneret and the die‐swell ratio near the spinneret was discussed. The entrance angle α of the entrance channel mainly influences the flow behavior of polymer solution in the spinneret and the die‐swell effect near the spinneret. As the decrease of the entrance angle α of the entrance channel, the vortices in the spinneret could be removed and the die‐swell ratio decreases. The increase of the length Ls of the exit channel results in the increase of pressure drop in the spinneret and the decrease of the die‐swell ratio. It is also found that the increase of the diameter D0 of the exit channel reduces the flow velocity of polymer solution and decreases the pressure drop in the spinneret at a constant mass flow rate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43962.
Producing high‐quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review
Authors: Kaur Jasjeet , Millington Keith , Smith Shaun 
Published: June 2016

ABSTRACTThe precursor fiber quality has a large impact on carbon fiber processing in terms of its performance, production yield, and cost. Polyacrylonitrile precursor fibers have been used commercially to produce strong carbon fibers with average tensile strength of 6.6 GPa. There is a scope to improve the average tensile strength of carbon fibers, since only 10% of their theoretical strength has been achieved thus far. Most attempts to increase the tensile strength of carbon fibers have been made during the conversion of precursor fiber to carbon fiber. This review highlights the potential opportunities to enhance the quality of the polyacrylonitrile‐based precursor fiber during polymer synthesis, spinning, and postspinning. These high‐quality precursor fibers can lead to new generation carbon fibers with improved tensile strength for high‐performance applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43963.
Chemorheological time‐temperature‐transformation‐viscosity diagram: Foamed EPDM rubber compound
Authors: Restrepo‐Zapata Nora Catalina , Eagleburger Ben , Saari Travis , Osswald Tim A , Hernández‐Ortiz Juan Pablo 
Published: June 2016

ABSTRACTThermal analysis, rheometry, and kinetic modeling are used to generate a comprehensive processability diagram for thermosetting and elastomeric resins. A chemorheological “time‐temperature‐transformation‐viscosity” diagram is proposed to fully characterize curing reactions toward process' on‐line control, optimization, and material design. Differential scanning calorimetry and thermogravimetric techniques are used to measure total reaction heat, degree of vulcanization, and cure kinetics. The viscosity, as a function of temperature and cure degree, is obtained from parallel plate rheometry. The auto‐catalytic Kamal–Sourour model, including a diffusion‐control mechanism, is used to model cure kinetics, while the Castro–Macosko model serves to model the rheological behavior. Non‐linear least‐squares regression and numerical integration are used to find models' parameters and to construct the chemorheological diagram. The usefulness of the proposed methodology is illustrated in the context of an industrial‐like Ethylene Propylene Diene Termononer rubber compound that includes a chemical blowing agent. Even though the rubber formulation contains crosslinking agents, primary and secondary accelerators, promoters, activators, and processing aids, the chemorheological diagram is obtained consistently, validating the proposed methodology to any thermosetting or elastomeric resin. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43966.
Influence of cure conditions on out‐of‐autoclave bismaleimide composite laminates
Authors: Anandan Sudharshan , Dhaliwal Gurjot S. , Samaranayake V. A. , Chandrashekhara K. , Berkel Thomas R. , Pfitzinger Doug 
Published: June 2016

ABSTRACTBismaleimides (BMI) are thermosetting polymers that are widely used in the aerospace industry due to their good physical properties at elevated temperatures and humid environments. BMI‐based composites are used as a replacement for conventional epoxy resins at higher service temperatures. Out‐of‐Autoclave (OOA) processing of BMI composites is similar to that of epoxies but requires higher cure temperatures. Polymer properties such as degree of cure and crosslink density are dependent on the cure cycle used. These properties affect mechanical strength as well as glass transition temperature of the composite. In the current research, carbon fiber/BMI composite laminates were manufactured by OOA processing. The void content was measured using acid digestion techniques. The influence of cure cycle variations on glass transition temperature and mechanical strength was investigated. Properties of manufactured specimens were compared with that of conventional autoclave cured BMI composites. Laminates fabricated via OOA processing exhibited properties comparable to that of autoclave cured composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43984.
Land Inequality or Productivity: What Mattered in Southern Vietnam after 1975?
Authors: Bui Minh‐Tam T. , Preechametta Arayah 
Published: June 2016

AbstractLand redistribution and agricultural collective production were the key components of agrarian reforms implemented by the Vietnamese Communist Party in the south of the country after 1975. Land inequality was serious in the region under the Republic of Vietnam's regime. The new government struggled with agricultural collectivisation contributing to the decline in rice productivity. This study explains the persistence of a market‐based agricultural production in the southern economy under the new political regime. Beside the economic reasons and arguments of local peasants' everyday politics cited in the literature, we argue that the de facto political power of the middle‐class landowners was an important factor impeding the performance of agricultural cooperatives. It also implies that agricultural productivity was more vital than land inequality during the study period. We apply the model of Acemoglu and Robinson explaining how de facto political power helps elites to maintain their economic institutions in spite of a political change.
Prosperity, Sustainability and the Measurement of Wealth
Authors: Mumford Kevin J. 
Published: June 2016

AbstractGross domestic product (GDP) and household income measures provide invaluable metrics of economic activity in an economy, but they tell us little about the sustainability of the economic trends. National wealth accounting can be utilised to determine the size of the underlying productive base, which provides insight into the sustainability of economic activities and indicates the potential for intergenerational well‐being. An empirical methodology was developed to measure wealth and then used to analyse multiple Asian countries. A common theme found across the Asian countries was the depletion of natural capital (forests, minerals and energy) and the development of human and produced capital. A strong correlation between growth in GDP per capita and wealth per capita was also found, but there are instances of GDP growth and wealth growth having different signs.
Nongovernmental Organizations and Influence on Global Public Policy
Authors: Tortajada Cecilia 
Published: June 2016

AbstractNongovernmental organizations (NGOs) were once considered as altruistic groups which aim was to impartially influence public policy with no vested interests. Nevertheless, this perception has changed. They are increasingly perceived as groups that prioritize their own ideologies or that respond to the interests of their donors, patrons, and members rather than to those of the groups they represent. This article discusses the politics of NGOs in the present changing globalized world as agents concerned with social and environmental change as much as with their own causes. It argues that numerous NGOs are as much a part of national and international politics as any other interest group and that their practices and activities are not always in the search of a good society or the common good.
Take‐off, Persistence and Sustainability: The Demographic Factor in Chinese Growth
Authors: Cai Fang , Lu Yang 
Published: June 2016

AbstractWith the reduction of the working‐age population and the increase of the population dependency ratio as the main indicators of the diminishing demographic dividend, China's potential growth rate is decreasing. Our results suggest that the demographic dividend contributed to nearly one fourth of the economic growth in China in the past three decades, while total factor productive growth explains another third and capital accumulation explaining the remaining growth (nearly half). China's potential growth rate will continue to slow—it was nearly 10 per cent during 1980–2010 but 6.65 per cent on average during 2016–2020—because of the diminishing demographic dividend, but reform measures are conductive to clearing the institutional barriers to the supply of factors and productivity, buffering the potential growth rate. The aggregate reform dividend could reach to 1–2 per cent on average during 2016–2050.
Evidence for a quadruplex structure in the polymorphic hs1.2 enhancer of the immunoglobulin heavy chain 3’ regulatory regions and its conservation in mammals
Authors: Sette Marco , D'Addabbo Pietro , Kelly Geoffrey , Cicconi Alessandro , Micheli Emanuela , Cacchione Stefano , Poma Anna , Gargioli Cesare , Giambra Vincenzo , Frezza Domenico 
Published: June 2016

ABSTRACTRegulatory regions in the genome can act through a variety of mechanisms that range from the occurrence of histone modifications to the presence of protein‐binding loci for self‐annealing sequences. The final result is often the induction of a conformational change of the DNA double helix, which alters the accessibility of a region to transcription factors and consequently gene expression. A ∼300 kb regulatory region on chromosome 14 at the 3' end (3'RR) of immunoglobulin (Ig) heavy‐chain genes shows very peculiar features, conserved in mammals, including enhancers and transcription factor binding sites. In primates, the 3'RR is present in two copies, both having a central enhancer named hs1.2. We previously demonstrated the association between different hs1.2 alleles and Ig plasma levels in immunopathology. Here, we present the analysis of a putative G‐quadruplex structure (tetraplex) consensus site embedded in a variable number tandem repeat (one to four copies) of hs1.2 that is a distinctive element among the enhancer alleles, and an investigation of its three‐dimensional structure using bioinformatics and spectroscopic approaches. We suggest that both the role of the enhancer and the alternative effect of the hs1.2 alleles may be achieved through their peculiar three‐dimensional‐conformational rearrangement. © 2017 The Authors Biopolymers Published by Wiley Periodicals, Inc. Biopolymers 105: 768–778, 2016.
Solvation driven conformational transitions in the second transmembrane domain of mycobacteriophage holin
Authors: Lella Muralikrishna , Mahalakshmi Radhakrishnan 
Published: June 2016

ABSTRACTHolins are pore‐forming membrane proteins synthesized by lytic phages. The second transmembrane domain (TM2) of Mycobacteriophage D29 holin presents an Ala‐ and Gly‐rich sequence, with a currently unknown structure and function. In this study, we present the spectroscopic characterization of synthetic TM2 in various solvents, detergents, and lipids. We find that TM2 adopts α‐helical conformation under conditions that promote intra‐strand hydrogen bonding, such as organic solvents and detergent micelles. When we transfer the peptide to a well‐hydrated environment, a polyproline II‐like structure is obtained. Surprisingly, we find that the polyproline II–like conformation is retained in lipid vesicles. Based on our results, we present a putative role for TM2 in the process of pore formation by holin. © 2016 The Authors. Peptide Science Published by Wiley Periodicals, Inc. Biopolymers (Pept Sci) 108: 1–10, 2017.
Cortical bone fracture analysis using XFEM – case study
Authors: Idkaidek Ashraf , Jasiuk Iwona 
Published: June 2016

SummaryWe aim to achieve an accurate simulation of human cortical bone fracture using the extended finite element method within a commercial finite element software abaqus. A two‐dimensional unit cell model of cortical bone is built based on a microscopy image of the mid‐diaphysis of tibia of a 70‐year‐old human male donor. Each phase of this model, an interstitial bone, a cement line, and an osteon, are considered linear elastic and isotropic with material properties obtained by nanoindentation, taken from literature.The effect of using fracture analysis methods (cohesive segment approach versus linear elastic fracture mechanics approach), finite element type, and boundary conditions (traction, displacement, and mixed) on cortical bone crack initiation and propagation are studied. In this study cohesive segment damage evolution for a traction separation law based on energy and displacement is used. In addition, effects of the increment size and mesh density on analysis results are investigated.We find that both cohesive segment and linear elastic fracture mechanics approaches within the extended finite element method can effectively simulate cortical bone fracture. Mesh density and simulation increment size can influence analysis results when employing either approach, and using finer mesh and/or smaller increment size does not always provide more accurate results. Both approaches provide close but not identical results, and crack propagation speed is found to be slower when using the cohesive segment approach. Also, using reduced integration elements along with the cohesive segment approach decreases crack propagation speed compared with using full integration elements. Copyright © 2016 John Wiley & Sons, Ltd.
A performance analysis of a mimetic finite difference scheme for acoustic wave propagation on GPU platforms
Authors: Otero Beatriz , Francés Jorge , Rodriguez Robert , Rojas Otilio , Solano Freysimar , Guevara‐Jordan Juan 
Published: June 2016

SummaryRealistic applications of numerical modeling of acoustic wave dynamics usually demand high‐performance computing because of the large size of study domains and demanding accuracy requirements on simulation results. Forward modeling of seismic motion on a given subsurface geological structure is by itself a good example of such applications, and when used as a component of seismic inversion tools or as a guide for the design of seismic surveys, its computational cost increases enormously. In the case of finite difference methods (or any other volumen‐discretization scheme), memory and computing demands rise with grid refinement, which may be necessary to reduce errors on numerical wave patterns and better capture target physical devices. In this work, we present several implementations of a mimetic finite difference method for the simulation of acoustic wave propagation on highly dense staggered grids. These implementations evolve as different optimization strategies are employed starting from appropriate setting of compilation flags, code vectorization by using streaming SIMD extensions Advanced Vector Extensions (AVX), CPU parallelization by exploiting the Open Multi‐Processing framework to the final code parallelization on graphics processing unit platforms. We present and discuss the increasing processing speed up of this mimetic scheme achieved by the gradual implementation and testing of all these performance optimizations. In terms of simulation times, the performance of our graphics processing unit parallel implementations is consistently better than the best CPU version. Copyright © 2016 John Wiley & Sons, Ltd.
A multi‐channel architecture for metadata management in cloud storage systems by binding CPU‐cores to disks
Authors: Duan Hancong , Xiang Xiaoke , Zhang Yulu , Min Geyong , Zhan Wenhan , Lv Pengcheng 
Published: June 2016

SummaryMetadata operations have become dominant file operations in the storage systems. In the scenarios of read‐more and write‐less of massive small files, the current distributed file systems suffer from the unsatisfying performance and scalability of metadata service because of random disk I/O during metadata operations. In this paper, a highly efficient metadata management architecture for cloud storage systems is proposed. The cluster design significantly improves the scalability of the system. A concept of the disk I/O channel is introduced, which is an independent data storage pipe by binding an independent CPU‐core to each physical disk. In addition, a multi‐channel fast key‐value storage engine is proposed to provide the extremely efficient performance for the underlying storage service, which takes full advantages of multi‐core processors and parallel disks I/O. Besides, a new dynamic load‐balancing strategy is proposed to reduce load thrashing and improve the precision of rebalancing among the clusters. Performance measurements under a variety of benchmarks show that the metadata management is capable of handling the massive small files storage and the performance is improved significantly compared to the existing solutions. Copyright © 2016 John Wiley & Sons, Ltd.