bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic Enantioselective Reaction of α‐Aminoacetonitriles Using Chiral Bis(imidazoline) Palladium Catalysts
Authors: Kondo Masaru , Nishi Tomoki , Hatanaka Tsubasa , Funahashi Yasuhiro , Nakamura Shuichi 
Published: May 2015

AbstractThe catalytic enantioselective reaction of diphenylmethylidene‐protected α‐aminoacetonitriles with imines has been developed. Good yields and diastereo‐ and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts. The reaction of α‐aminonitriles with di‐tert‐butyl azodicarboxylate afforded chiral α,α‐diaminonitriles in high yields with high enantioselectivities.
Thermal conductivity and electromagnetic shielding effectiveness of composites based on Ag‐plating carbon fiber and epoxy
Authors: Li Junpeng , Qi Shuhua , Zhang Mengyu , Wang Zhaofu 
Published: May 2015

ABSTRACTThermally conductive and electromagnetic interference shielding composites comprising low content of Ag‐plating carbon fiber (APCF) were fabricated as electronic packing materials. APCF as conductive filler consisting of carbon fiber (CF) employed as the structural component to reinforce the mechanical strength, and Ag enhancing electrical conductivity, was prepared by advanced electroless Ag‐plating processing on CF surfaces. Ag coating had a thickness of 450 nm without oxide phase detected. The incorporation of 4.5 wt % APCF into epoxy (EP) substrate yielded thermal conductivity of 2.33 W/m·K, which is approximately 2.6 times higher than CF–EP composite at the same loading. The APCF–EP composite performed electromagnetic shielding effectiveness of 38–35 dB at frequency ranging from 8.2 to 12.4 GHz in the X band, and electromagnetic reflection was the dominant shielding mechanism. At loading content of APCF up to 7 wt %, thermal conductivity of APCF–EP composites increased to 2.49 W/m·K. Volume resistivity and surface resistivity decreased to 9.5 × 103 Ω·cm and 6.2 × 102 Ω, respectively, which approached a metal. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42306.
Joint effects of rotational extrusion and TiO2 on performance and antimicrobial properties of extruded polypropylene copolymer pipes
Authors: Li Xiao , Pi Lin , Nie Min , Wang Qi 
Published: May 2015

ABSTRACTIn this study, effects of titanium dioxide (TiO2) and rotation extrusion on structures and properties of polypropylene random copolymer (PPR) pipes were investigated. The experimental results showed that with the presence of TiO2, not only the antibacterial ability of PPR pipe was improved significantly but also the toughness was enhanced since a large number of PP chains were promoted to crystallize into β‐form crystals. Furthermore, when rotation extrusion was introduced into the process of PPR pipe, the drag hoop flow caused by mandrel and die rotation was superposed on the axial flow, so the polymer melts in the annulus underwent a helical flow and its flow direction deviated from the axis to drive the molecular orientation off the axial direction, bringing out the increased hoop strength. As a result, PPR pipe with excellent performance was prepared under the combined effect of rotation extrusion and TiO2. The antibacterial activity was 99.2%, the hoop tensile strength reached 27.5 MPa, 67.7% higher than that of the convention‐extruded PPR pipe with TiO2, and the impact strength was 10.9 kJ/m2, increased by 81.6% compared to that of the rotation‐extruded pure PPR pipe. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42410.
Friction and wear behavior of styrene butadiene rubber‐based composites reinforced with microwave‐devulcanized ground tire rubber
Authors: Karabork Fazliye , Akdemir Ahmet 
Published: May 2015

ABSTRACTIn this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR) and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant power while varying the microwave exposure time. Devulcanized rubber (DV‐R) and untreated GTR were revulcanized by mixing with SBR at different rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests were conducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experimental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samples for comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcanization functionalization of ground tire rubber. In general, DV‐R/SBR composites exhibited improvement in both mechanical and tribological properties. However, the enhanced compatibility of DV‐R resulting from the specific chemical coupling of DV‐R with SBR was crucial for the mechanical, friction and wear properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42419.
Polythiophene based fluorescent probe for copper ions with high sensitivity
Authors: Guo Chaoxia , Jiang Shouxiang , Zhu Wenxue , Yang Xiuxia , Pei Meishan , Zhang Guangyou 
Published: May 2015

ABSTRACTTwo new conjugated polymers poly{3‐({4‐[(2‐hydrazino‐2‐oxoethyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P1) and poly{3‐({4‐[(3‐hydrazino‐3‐oxopropyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P2) were synthesized, and their optical properties were investigated. P1 exhibited excellent selectivity toward Cu2+ ions in 50% water solution, the fluorescence color of P1 changed distinctly from greenyellow to colorless in the presence of Cu2+ under UV‐light, while introduction of other metal ions could not induce such significant variation. Moreover, highly sensitive detection of Cu2+ ions was demonstrated in 90% water solution. Its high metal‐chelating capability allowed Cu2+ recognition with a detection limit of 3.2 × 10−10 M. These results indicated that this kind of nonionic polymer containing multidentate ligand could be used as a highly selective and sensitive chemosensor for Cu2+ detection. The proposed binding mode of P1 with Cu2+ was supported by DFT calculation using Gaussian 03. Unlike P1, P2 showed no obvious fluorescent change in the presence of various metal ions due to its space steric hindrance resulted from N/O distribution on the side chain of P2. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42440.
Improving the hydrophobicity of nylon fabric by consecutive treatment with poly(acrylic acid), tetraethylorthosilicate, and octadecylamine
Authors: Du Jinmei , Luo Xiongfang , Fu Zhen , Xu Changhai , Ren Xuehong , Gao Weidong , Li Yong 
Published: May 2015

ABSTRACTNylon fabric was consecutively treated with poly(acrylic acid) (PAA), tetraethylorthosilicate (TEOS), and octadecylamine (OA) to improve its hydrophobicity. We proposed that PAA could be used as a mediator between nylon and OA to provide a high density of the carboxyl moiety. TEOS was used to increase the surface roughness of the nylon fabric by hydrolysis and condensation, and OA was used to reduce the surface energy of the nylon fabric with its long alkyl chains. Both the increase in the surface roughness and the reduction in the surface energy contributed to the improvement of the hydrophobicity of the nylon fabric. The hydrophobicity of the treated nylon fabric was evaluated by the measurement of the water contact angle, water resistance to spray, and hydrostatic pressure. Scanning electron microscopy images showed that the surface roughness of the nylon fabric was significantly increased by treatment with TEOS. The nylon fabric with the PAA/TEOS/OA consecutive treatment exhibited a water contact angle of 125°, a resistance to water spray of 90, and a hydrostatic pressure of 275 mm. It was interesting to find that the PAA/TEOS/OA consecutive treatment slightly enhanced the wrinkle recovery but had no apparent effects on the degree of whiteness and the breaking strength of the nylon fabric. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42456.
Thermal conductivity of polyimide/boron nitride nanocomposite films
Authors: Diaham Sombel , Saysouk François , Locatelli Marie‐Laure , Belkerk Boubakeur , Scudeller Yves , Chiriac Rodica , Toche François , Salles Vincent 
Published: May 2015

ABSTRACTThe thermal conductivity of polyimide/boron nitride (PI/BN) nanocomposite thin films has been studied for two sizes of BN nanofillers (40 and 120 nm) and for a wide range of content. A strong influence of BN particle size on the thermal conduction of PI has been identified. In the case of the largest nanoparticles (hexagonal‐BN), the thermal conductivity of PI/h‐BN (120 nm) increases from 0.21 W/mK (neat PI) up to 0.56 W/mK for 29.2 vol %. For the smaller nanoparticles (wurtzite‐BN), PI/w‐BN (40 nm), we observed two different behaviors. First, we see a decrease until 0.12 W/mK for 20 vol % before increasing for higher filler content. The initial phenomenon can be explained by the Kapitza theory describing the presence of an interfacial thermal resistance barrier between the nanoparticles and the polymer matrix. This is induced by the reduction in size of the nanoparticles. Modeling of the experimental results allowed us to determine the Kapitza radius aK for both PI/h‐BN and PI/w‐BN nanocomposites. Values of aK of 7 nm and >500 nm have been obtained for PI/h‐BN and PI/w‐BN nanocomposite films, respectively. The value obtained matches the Kapitza theory, particularly for PI/w‐BN, for which the thermal conductivity is expected to decrease compared to that of neat PI. The present work shows that it seems difficult to enhance the thermal conductivity of PI films with BN nanoparticles with a diameter <100 nm due to the presence of high interfacial thermal resistance at the BN/PI interfaces. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42461.
Numerical simulation on residual thickness of pipes with curved sections in water‐assisted co‐injection molding
Authors: Kuang Tang‐Qing , Xu Bai‐Ping , Zhou Guo‐Fa , Turng Lih‐Sheng 
Published: May 2015

ABSTRACTThe residual thicknesses of the skin and the inner layers are important quality indicators of water‐assisted co‐injection molding (WACIM) process or overflow WACIM (O‐WACIM) parts. At the curved section, the residual thicknesses change significantly. A numerical simulation program based on the computational fluid dynamics method was developed to simulate the O‐WACIM process. After the numerical simulation program was validated with the experimental results, it was used to study the effects of the bending radii and bending angles on the residual thicknesses of the skin and inner layers of O‐WACIM parts. The results showed that the penetration of the inner melt and water was always close to the inner concave side due to the higher local pressure gradient and temperature. The effects of processing parameters on the residual thicknesses of the skin and inner layers were investigated using the orthogonal simulation method. It was found that the residual thicknesses of the skin/inner layer at the inner concave/outer convex side are mainly influenced by different parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42468.
Structure–property relationship of polyimide fibers containing ether groups
Authors: Chang Jingjing , Niu Hongqing , He Min , Sun Meng , Wu Dezhen 
Published: May 2015

ABSTRACTThe copolyimide (co‐PI) fibers with outstanding mechanical properties were prepared by a two‐step wet‐spinning method, derived from the design of combining 4,4′‐oxydianiline (ODA) with the rigid 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)/p‐phenylenediamine (p‐PDA) backbone. The mechanical properties of PI fibers were drastically improved with the optimum tensile strength of 2.53 GPa at a p‐PDA/ODA molar ratio of 5/5, which was approximately 3.7 times the tensile strength of BPDA/p‐PDA PI fibers. Two‐dimensional wide‐angle X‐ray diffraction indicated that the highly oriented structures were formed in the fibers. Two‐dimensional small‐angle X‐ray scattering revealed the existence of the needle‐shaped microvoids aligned parallel to the fiber axis, and the introduction of ODA led to the reduction in the size of the microvoids. As a result, the significantly improved mechanical properties of PI fibers were mainly attributed to the gradually formed homogeneous structures. The co‐PI fibers also exhibited excellent thermal stabilities of up to 563°C in nitrogen and 536°C in air for a 5% weight loss and glass transition temperatures above 279°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42474.
Clinical Phenotype Classifications Based on Static Varus Alignment and Varus Thrust in Japanese Patients With Medial Knee Osteoarthritis
Authors: Iijima Hirotaka , Fukutani Naoto , Aoyama Tomoki , Fukumoto Takahiko , Uritani Daisuke , Kaneda Eishi , Ota Kazuo , Kuroki Hiroshi , Matsuda Shuichi 
Published: May 2015

ObjectiveTo investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA).MethodsPatients in an orthopedic clinic (n = 266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n = 173), dynamic varus (n = 17), static varus (n = 50), and static varus + dynamic varus (n = 26). The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity.ResultsMultiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08–12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19–320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results.ConclusionVarus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA.
Brief Report: Clinical Course Over Two Years in Patients With Early Nonradiographic Axial Spondyloarthritis and Patients With Ankylosing Spondylitis Not Treated With Tumor Necrosis Factor Blockers: Results From the German Spondyloarthritis Inception Cohort
Authors: Poddubnyy Denis , Haibel Hildrun , Braun Jürgen , Rudwaleit Martin , Sieper Joachim 
Published: May 2015

ObjectiveTo investigate the clinical course of disease over 2 years in patients with nonradiographic axial spondylarthritis (SpA) and patients with ankylosing spondylitis (AS).MethodsThe study group comprised 303 patients with axial SpA (158 patients with AS and a symptom duration of ≤10 years and 145 patients with nonradiographic axial SpA and a symptom duration of ≤5 years) who did not receive tumor necrosis factor (TNF) blockers during 2 years of followup.ResultsThe Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) did not differ between patients with nonradiographic axial SpA and those with AS at any time point during followup. The Bath Ankylosing Spondylitis Functional Index was significantly higher in patients with AS at baseline only, but spinal mobility was generally better in patients with nonradiographic SpA compared with those with AS. At all time points, C‐reactive protein (CRP) levels were significantly higher in patients with AS compared with patients with nonradiographic axial SpA. Accordingly, the Ankylosing Spondylitis Disease Activity Score (ASDAS) was significantly higher in the patients with AS at 2 of 4 time points. When patients with a BASDAI score of ≥4 plus an elevated CRP level at baseline were analyzed over time, there were no significant differences in the proportions of patients with nonradiographic axial SpA and those with AS who reached low disease activity status at ≥2 time points during 2 years of followup when a clinical definition of low disease activity was used (38% and 35%, respectively, achieved a BASDAI score of <4, and 13% and 15%, respectively, achieved a score of ≤2). When definitions that included the CRP level were used, however, a greater percentage of patients with nonradiographic axial SpA achieved low disease activity (25% of patients with nonradiographic axial SpA and 10% of patients with AS achieved a BASDAI score of <4 and a normal CRP level, and 13% of patients with nonradiographic axial SpA and 3% of those with AS achieved ASDAS‐defined low disease activity).ConclusionPatients with nonradiographic axial SpA and those with AS who were not treated with TNF blockers demonstrated a similar clinical disease course over 2 years. Patients with nonradiographic axial SpA achieved a status of low disease activity more frequently than those with AS if outcome parameters that included the CRP level were used.
Performance of an Eco‐Driving Model Predictive Control System for HEVs during Car Following
Authors: Yu Kaijiang , Liang Qing , Hu Zhiguo , Yang Junqi , Zhang Hongwei 
Published: May 2015

AbstractThis paper presents a model predictive control approach for the energy management problem of hybrid electric vehicles (HEVs) with variable time headway during car following. The new features of this study are as follows. First, a new method using model predictive control with fixed time headway is proposed to improve fuel economy outside the HEV. Second, the battery state of charge profile is scheduled systematically to improve fuel economy inside the HEV compared with the vehicle spacing influence outside the HEV. Computer simulation results are shown using the approaches with variable time headway and fixed time headway. The conclusion is that the model predictive control approach is effective for the energy management problem of the HEV system during car following.
Event‐Triggered Control for Multi‐Agent Systems with General Directed Topology and Time Delays
Authors: Gao Lan , Liao Xiaofeng , Li Huaqing , Chen Guo 
Published: May 2015

AbstractRecent years have witnessed a growing interest in event‐triggered strategies for coordination and cooperative control of multi‐agent systems. However, the most previous works and developments focus on the interactive network that has no communication delays. This paper deals with the consensus problem of an agent system with event‐triggered control strategy under communication time delays. We first propose a time delays system model, then present a novel event triggering function that not only avoids continuous communication but also excludes the Zeno behavior. Furthermore, we provide the consensus analysis using an inequality technique instead of the traditional linear matrix inequality method, and we demonstrate that the inter‐event times for each agent are strictly positive, which implies that the Zeno behavior can be excluded. Finally, simulation results show the effectiveness of the proposed approach and illustrate the correctness of the theoretical results.
Zn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white LEDs by solid‐state reaction
Authors: Wu Yibing , Zhao Fengyang , Piao Xianqing , Ruan Kaibin 
Published: May 2015

AbstractZn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white light‐emitting diodes (LEDs) were synthesized by a solid‐state method. The structure and morphology of the obtained phosphor samples were observed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), and the impact of Ca, Zn and Eu content on their photoluminescence properties was studied. The results indicated that Zn not only participates in the formation of defects in suitable lattice matrices but also has a role in flux in the transformation from ZnO to Zn2TiO4, which is beneficial for the enhancement of photoluminescence properties. Photoluminescence test data showed that the Zn‐doped phosphor is excited efficiently by near‐ultraviolet (NUV) light at wavelengths around 398 nm and emits an intense red light with a broad peak around 616 nm corresponding to the 5D0→7F2 transition of Eu3+. The intensity of this phosphor emission is three times stronger than that without Zn‐doping. Furthermore, this phosphor has very good thermal stability, high color purity and a low sintered temperature, all of which suggest its potential as a promising red phosphor for white LEDs. Copyright © 2015 John Wiley & Sons, Ltd.
Thermoluminescence properties of gamma‐irradiated nano‐structure hydroxyapatite
Authors: Shafaei M. , Ziaie F. , Sardari D. , Larijani M. M. 
Published: May 2015

ABSTRACTThe suitability of nano‐structured hydroxyapatite (HAP) for use as a thermoluminescence dosimeter was investigated. HAP samples were synthesized using a hydrolysis method. The formation of nanoparticles was confirmed by X‐ray diffraction and average particle size was estimated to be ~30 nm. The glow curve exhibited a peak centered at around 200 °C. The additive dose method was applied and this showed that the thermoluminescence (TL) glow curves follow first‐order kinetics due to the non‐shifting nature of Tm after different doses. The numbers of overlapping peaks and related kinetic parameters were identified from Tm–Tstop through computerized glow curve deconvolution methods. The dependence of the TL responses on radiation dose was studied and a linear dose response up to 1000 Gy was observed for the samples. Copyright © 2015 John Wiley & Sons, Ltd.
DNA cyclization and looping in the wormlike limit: Normal modes and the validity of the harmonic approximation
Authors: Giovan Stefan M. , Hanke Andreas , Levene Stephen D. 
Published: May 2015

ABSTRACTFor much of the last three decades, Monte Carlo‐simulation methods have been the standard approach for accurately calculating the cyclization probability, J, or J factor, for DNA models having sequence‐dependent bends or inhomogeneous bending flexibility. Within the last 10 years approaches based on harmonic analysis of semi‐flexible polymer models have been introduced, which offer much greater computational efficiency than Monte Carlo techniques. These methods consider the ensemble of molecular conformations in terms of harmonic fluctuations about a well‐defined elastic‐energy minimum. However, the harmonic approximation is only applicable for small systems, because the accessible conformation space of larger systems is increasingly dominated by anharmonic contributions. In the case of computed values of the J factor, deviations of the harmonic approximation from the exact value of J as a function of DNA length have not been characterized. Using a recent, numerically exact method that accounts for both anharmonic and harmonic contributions to J for wormlike chains of arbitrary size, we report here the apparent error that results from neglecting anharmonic behavior. For wormlike chains having contour lengths less than four times the persistence length, the error in J arising from the harmonic approximation is generally small, amounting to free energies less than the thermal energy, kBT. For larger systems, however, the deviations between harmonic and exact J values increase approximately linearly with size. © 2015 Wiley Periodicals, Inc. Biopolymers : 527–537, 2015.