bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical, Morphological, and Structural Characteristics of Caroa (Neoglaziovia variegata) Fibres
Authors: d'Almeida J.R.M. , d'Almeida A.L.F.S. , De Carvalho L.H.
Published: September 2018

The surface morphology, thermal behaviour and tensile mechanical properties of raw caroa (Neoglaziovia variegata) fibres have been characterised. The influence of fibre washing with flowing tap water on the surface morphology and thermal properties of these fibres has also been investigated. The results show that gummy tissues are attached to the surface of the raw fibres and that washing leads to the partial removal of these tissues and to the exposure of the inner fibrillar structure of the fibres. Thermogravimetric analysis indicates that fibre thermal degradation is characterised by three main degradation stages corresponding, respectively, to water release at low temperatures, followed by decomposition of hemicellulose and of α-cellulose. Fibre washing produces an increase in the fibre thermal degradation temperature, Tonset, and in the thermal decomposition rate. These characteristics are associated with the removal of gummy tissues and with a decrease in the compactness of the fibres respectively. The tensile properties obtained place caroa as a low-to-medium-strength fibre when compared with other lignocellulosic fibres, but with a strength level similar to that of coir fibres, which, nowadays, are used commercially on a fairly large scale.
Nylon 66 Toughening Nylon 11 by in situ Polymerization
Authors: Guo Qiwen , Fan Chenglei , Liu Hongjun , Cai Yanli
Published: September 2018

In this paper, we employed in situ polymerization to synthesize the nylon 11/nylon 66 alloys. In nylon 11/nylon 66 alloys, the crystallization of introduced nylon 66 is impeded by the nylon 11 matrix. As a result, the amorphous nylon 66 is uniformly dispersed in nylon 11 matrix and there is no phase separation observed. In contrast, the crystalline nylon 11 and nylon 66 phases were separated. The nylon 11 was significantly toughened by incorporating a small amount of nylon 66 (3–10 wt.%) but its strength was still maintained.
Significant Improvement in Mechanical Performance for Grid-Stiffened Polymer Composites
Authors: Lin Zaiwen , Du Shanyi , Liang Yan , Liu Yongqi , Liu Fangfang , Hou Diyang
Published: September 2018

This work studies the static mechanical properties of grid stiffened polymer composites. This developed composite is expected to have an ultra-higher mechanical performance than traditional composite structures. Static mechanical measurements show that the combination of gridding reinforcement and epoxy polymer (Diglycidyl 4,5-epoxy cyclohexane-1,2-dicarboxylate) helps the advanced composite to possess extremely high mechanical properties, such as resistive properties in axial pressure (more than 160% improvement) and external pressure (more than 102% improvement) for comparison. Subsequently, the effects of wetting angle of reinforcement, quantity of gridding reinforcement, and type of grid on the mechanical properties of the advanced polymer composites have been studied and analyzed. Finally, the finite element model (FEM) method is employed to substantiate these experimental results. The FEM simulation results are in such great agreement with the experimental results that the standard deviations between them are strictly limited to 15%. Furthermore, it demonstrates that the FEM technology is an effective approach for predicting and optimizing structure design, as well as the mechanical behaviors.
Damping Analysis of Fibre-Reinforced Composites and Structure
Authors: Hong Y. , He X.D. , Wang R.G. , Li Y.B. , Zhang J.Z. , Zhang H.M.
Published: September 2018

The purpose of the paper is to analyze the damping characteristics of several advanced fibre-reinforced composites, and ulteriorly optimize the damping performance of a composite structure. Numerical modelling of the damping was developed considering the finite element method based on the modal strain energy. The modal damping characteristics of the fibre-reinforced composites were evaluated, including the modal frequencies, modal shapes and modal loss factors. The damping performances of different fibre-reinforced composites were compared. Furthermore, the damping performance of a laminated composite structure was optimized by considering the effects of different lay-up sequences and layer orientations. An optimum design scheme of the composite structure was presented.
Interfacial Optimization of Acetate Taffeta Fabric/PLA Composites
Authors: Kim Byung Sun , Yi Jin Woo , Ha Jong Rok , Kim Seul Ki , Song Jung Il
Published: September 2018

For the interfacial optimization of Acetate Taffeta Fabric (ATF) with Poly Lactic Acid (PLA), steady-state uniform atmospheric glow discharge (AGD) and Silane treatments were studied, respectively.

In AGD, the plasma polymerization time for ATF was varied up to 3 minutes. In silane treatments, three types of silane coupling agents, aminoethylaminopropyl-trimethoxysilane, 3-glycidoxypropyl-trimethoxysilane and 3-methacryloxypropyltrime-thoxysilane, were used respectively with concentrations ranging from 0 to 5%. Silane coupling agent was chosen since -OH in silane always reacts with -OH in PLA. Also, all three silanes have similar chemical structures with that of Lactic Acid. The sizing on the fabric was with a solution containing PVA, acryl and water at the ratio of 3:1:96. Peel tests were carried out for the surface modified fabrics before and after removing the sizing. Highest peel test results was obtained with 3% silane concentration. Tensile tests were carried out before analyzing the fracture surface of the composites by scanning electron microscope. Compared to raw fabric, plasma and silane treatments have improved the tensile strength at maximum of 30.4 and 27.4%, respectively.
Prediction of Critical Center Load for Bi-stable Laminates
Authors: Dai Fuhong , Li Hao , Du Shanyi
Published: September 2018

Finite element analysis (FEA) was used to study the snap-through of bi-stable laminate. Along with displacement load, the “static stabilize” algorithm in ABAQUS was employed in FEA. Two kinds of finite models, a two-step model (with internal thermal stress) and an one-step model (without internal thermal stress) were presented. The results show that the thickness defect of specimen must be considered, the error of critical load predicted by the modified two-step model which considers thickness defect is 0.7%. Comparison between one-step model and two-step model indicates that when the deformation is small, the one-step model is accurate and more convenient. Otherwise, the two-step model must be employed.
Numerical Study on Effects of Interaction between Rubber Mould and Lay-up on Consolidation of L-shaped Laminates in Autoclave Process
Authors: Sun Jing , Li Yanxia , Li Min , Gu Yizhuo , Zhang Zuoguang
Published: September 2018

For autoclave process, a rubber mould is widely used to facilitate the pressure transfer of the external pressure to fabricate high performance complex composite structures. The shear interaction between the laminate and the rubber mould may have effects on the actual pressure acting on the part and the resin flow in the laminate during the consolidation process. This paper presents the numerical investigations on the effects of tool-part interaction on the pressure transfer and the consolidation of L-shaped laminates in autoclave process. In order to represent the slippage and the shear action between the laminate and the rubber mould, a shear layer was introduced to the finite element models. Simulations were performed on carbon fiber/bismaleimide (BMI) resin L-shaped laminates molded with the rubber male mould in autoclave. For the quasi-isotropic laminates, the simulated results indicate that the tool-part interaction has significant effects on the resin pressure and the compaction behavior in the corner region of L-shaped laminates, but has little impact on the final thickness of the part. The consideration of the tool-part shear interaction is critical for accurate prediction of the resin pressure in the laminate and is much helpful for analyzing the forming of defects and the quality of the composite parts.
Preparation and Characterization of Self-healing Polymeric Materials with Microencapsulated Epoxy and Imidazoline Derivatives Curing Agent
Authors: Wang Rongguo , Hu Honglin , Liu Wenbo , Guo Qiong
Published: September 2018

Binary self-healing system consisting of epoxy-containing microcapsules and latent curing agent based on anionic polymerization was investigated. When cracks propagated in the composites, the embedded microcapsules would be damaged and the epoxy healing agent would be released. The latent curing agent used in this study can be well dispersed in epoxy matrix during composites manufacturing, and hence activate the released epoxy wherever it is. As a result, self-healing of the cracked sites is successfully achieved through curing of the released epoxy healing agent. This paper also investigated the preparation and performance of microcapsules synthesized by situ polymerization. The mechanism of anionic chain polymerization between epoxy and curing agent was investigated. On the basis of this work, self-healing ability of the epoxy filled with the healing system was evaluated. It was found that the distribution of microcapsules and latent curing agent greatly influences the healing efficiency but not the stoichiometric composition, and the optimal weight ratio of microcapsules and curing agent 2MZ-AZINE are 15 wt.% and 2 wt.%, offering a ~83% healing efficiency.
Study on Hygrothermal Properties of Carbon Fiber Reinforced Composites Aged in Cyclic Environment
Authors: Wang Rongguo , Jiang Long , Liu Wenbo , Lv Xinying
Published: September 2018

In this study, we investigate the cyclic hygrothermal effects of moisture, high temperature and low temperature states on the durability of carbon fiber reinforced epoxy resin composites (CF/Epoxy). CF/Epoxy composites are prepared by curing in autoclave. The moisture diffusion behavior of CF/Epoxy composites is analyzed by moisture content as a function of time. In addition, the effects of cyclic conditions on the inter-laminar shear properties and microstructure of composites are investigated through inter-laminar shear strength (ILSS) tests and scanning electron microscope (SEM) analysis respectively. The test results show that composites have a good retention rate of ILSS. The SEM photographs, associated with the mentioned ILSS test results demonstrate that desorption cycle makes more remarkable degradation of ILSS compared to aging in water, and it is necessary to calculate the effect of low-temperature wet condition when we design accelerated aging cycle.
Investigation of the Curing Kinetics and Rheological Behavior of Multifunctional Epoxy Resin System
Authors: Zhengwei Zhou , Ruicheng Bai , Musu Ren , Jinliang Sun , Ze Zhou , Qingping Hu , Chuanbin Wang
Published: September 2018

The curing reactivity and viscosity of AG-70 epoxy resin system with MNA as the curing agent and 2,4-EMI as the accelerator promoter were measured by using non-isothermal differential scanning calorimetry (DSC) and RS600 Rotational Rheometer, respectively. According to the DSC curves at different heating rates, the curing parameters such as the gelation temperature, the peak temperature and the treat temperature were obtained by using T-β curve extrapolation, the kinetic parameters of the curing reaction were determined by using Kissinger, Ozawa and Crane equation, including the apparent activation energy, the pre-exponential frequency and the curing reaction order. Then the kinetic model based on an nth order reaction equation was set up. The experimental data of the viscosity behavior were analyzed, and modified dual-Arrhenius viscosity model was established to predict the isothermal rheological behavior. The relationship between gel-time and temperature was also analyzed.
The Study of Single-walled Nanotube Reinforced Epoxy Composites by Molecular Dynamics
Authors: Huang Jen-Ching , Chiu Cheng-Yi
Published: September 2018

Recently, enhance the mechanical property of nanocomposite were used by adding the nanotubes. The mechanical properties of the nanocomposite were affected by interfacial bonding energy between nanotubes and polymers. In this paper, the interfacial bonding energy and Young's moulds of single-walled nanotube (SWNT) reinforced epoxy composites were investigated using molecular dynamics (MD) simulations based on a cured epoxy resin model, which was constructed by incorporating three-dimensional crosslinks formed during curing reaction. The structure types of SWNT include the armchair, zigzag and chiral was used in this study. After simulation, adding SWNT in the epoxy resin really has been reinforced effect, and the larger chiral angle of SWNT the better to strengthen. The study also calculated the interfacial bonding energy between the epoxy and the SWNT affects the ability of strengthening to the composite of SWNT. Within the range of 273K-473K, the temperature has a little influence on Young's moulds of SWNT reinforced epoxy composites.
Preparing and Structure of a Porous Nano-HA/CS/PVA Composite by Freeze-drying
Authors: Wang Feng , Guo Enyan
Published: September 2018

Novel tissue engineering scaffold material porous hydroxyapatite, with interconnected pores, allows tissue fluid circulation and provides nutrient for new bone. In the work, Nano-HA/CS/PVA composites were prepared through a co-precipitation method with (NH4)2HPO4, Ca(NO3)2·4H2O, chitosan(CS) and polyvinyl alcohol (PVA) as raw materials. Frozen with liquid nitrogen, and then the porous scaffolds were fabricated by freeze-drying. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of chemical bonds among HA, CS and PVA and were discussed. Scanning electron microscopy (SEM) analysis revealed that the composites have interconnected porous structures.
Fluorescence of a New Phenanthrolin Derivative Sensitive to DNA Induced by Single- and Two-photon Excitation
Authors: Zian Zhang , Rui-xing Xie , Jin-shui Yao , Xiang-long Meng , Ying-kai Liu , Xiao-qiang Yu , Min-hua Jiang
Published: September 2018

A novel two-photon absorption (TPA) material with phenanthrolin as acceptor (BSIPB) has been firstly synthesized and studied as possible fluorescence probe for nucleic acids detection. The single-photon and two-photon fluorescence properties of the dye in the unbound state and in DNA complexes were investigated. Some quantum yields and TPA cross sections at important points were calculated. The results showed that BSIPB can be used as an efficient fluorescent probes for DNA detection and imaging under both single-photon excitation (SPE) and two-photon excitation (TPE).
High Performance Composites of Polybenzoxazine and Polyarylene Ether Nitriles (PEN)
Authors: Chen Wenjin , Lei YaJie , Liu Xiaobo
Published: September 2018

Polybenzoxazine (PBa) was modified by polyarylene ether nitriles (PEN) via in situ curing reaction of benzoxazine in the presence of PEN to improve toughness and thermal properties. DSC measurements of the cured blends containing PBa and PEN showed single glass-transition temperatures (Tg's) when the amount of PEN in the blends less than 20%, and the blends have significantly higher glass transition temperatures than those of each homopolymer. Tensile measurements of the films revealed that the strength and elongation was dramatically enhanced by the addition of PEN, the toughness of the PBa/PEN films was greatly enhanced. The thermal stability also increased with the increase of PEN content as evidenced by TGA. All of the mechanical and thermal characteristics show that the blends can be good candidates for the matrix resin of advanced composite materials.
Investigation on Dynamic Mechanical Properties of Crosslinked Poly(styrene-co-divinylbenzene) Bulk Copolymers: Effect of Divinylbenzene Content
Authors: Zhu Quanyao , Yang Qing , Yu Yue , Wang XiaoQing , Wu Fei , Chen Wen
Published: September 2018

The crosslinked poly(styrene-co-divinylbenzene) (CL-p(St-DVB)) bulk copolymers were fabricated by free-radical bulk crosslinking copolymerization (FCC) with styrene as monomer and divinylbenzene (DVB) as crosslinker. The viscoelastic properties of the crosslinked copolymers were investigated by dynamic mechanical thermal analysis (DMTA) as a function of temperature and frequency. The Arrhenius relationship was employed to calculate the activation energy of the α-relaxation transition for the specimens. The results revealed that the storage modulus (E′) of the copolymer networks enhanced with the rising DVB content. The loss tangent (tanδ) peaks were lower and broader. The dynamic mechanical responses of the CL-p(St-DVB) networks were also strongly depended on the test frequency.
A New Hydrophobic Associating Polymer
Authors: Liu Chuntian , Wu Xiaolin , Li Xing , Yu Xiaodan , Zhao Xin
Published: September 2018

The properties of a new hydrophobic associating polymer were evaluated in detail in this paper. The polymer enhances the effect of increasing viscosity for the assembling action of functional groups in molecular chain. Alkali and surfactant promote the association and result in the increasing of viscosity, so the concentration of polymer in ASP solution is less than that in solution without alkali and surfactant. The viscosity of polymer solution restored again when shear effect decreased or disappeared; the characteristic will make the polymer used in oilfield advantageously. The polymer has synergistic effect with surfactant, so the interfacial tension of oil and water was ultra-low in a wide range of chemical concentration; it is propitious to improve displacement efficiency. When the oil recovery is approximate, the amount of new hydrophobic associating polymer is 20% less than that of HPAM.
Properties of a Novel Siloxane-containing Epoxy Resin
Authors: Sun Wenbing , Zhang Chaocan
Published: September 2018

To fabricate self-organized gradient material using bisphenol-A epoxy resin (E51) and siloxane, the properties of a novel synthesized siloxane-containing epoxy resin (SE) were investigated in advance. It is found that SE behaves like Newtonian fluid at low shear rates, while like non-Newtonian fluid at high shear rates. Similar to E51, SE is soluble in most solvents. Although curing process of two epoxy resins submits to first-order reaction kinetics, curing activity of SE is higher slightly. Contrary to the cured E51, the cured SE is hydrophobic and characterized by ductile fracture. It is also observed that the cured SE is more stable in thermal decomposition than the cured E51.
Electrical and Damping Composite Films of MWCNTs/P (Styrene-Butylacryl) Prepared via in situ Copolymerization
Authors: Zhou ChunHua , Liu Wei , Wu Lili , Feng Ying , Xu Min
Published: September 2018

Multi-walled carbon nanotubes (MWCNTs)/P(styrene-butyl acryl) composite latex was successfully synthesized by in-situ emulsion copolymerization to prepare MWCNTs/P(styrene-butyl acryl) composite film directly. The results by Raman spectra and FESEM showed that P(styrene-butyl acryl) copolymer molecules were combined assuredly with the surface of MWCNTs. MWCNTs coated with P(styrene-butyl acryl) could be dispersed in the emulsion evenly. Dynamic mechanical analysis showed that Tg, G′ and tanδ of the composites films were greater in the presence of MWCNTs. Specially the vibration damping property was enhanced at elevated temperatures, indicating the strong interaction between MWCNTs and P(styrene-butyl acryl) molecules to limit the motivation of P(styrene-butyl acryl) chains. The electrical conductivity increased with the adding of MWCNTs by 7 orders of magnitude on addition of 1.5 wt.% MWNTs. So the electrical and damping film has been prepared via in situ emulsion copolymerization.
Thermal Curing Induced Deformation of Fiber Composite Laminates
Authors: Wang Xiaoxia , Jia Yuxi , Wang Chengguo
Published: September 2018

The curing of fiber-reinforced composite laminates is a complex thermal-chemical-mechanical coupling process, during which composite laminates experience shape change because of resin thermal curing induced composite stress. For composite structures with high shape precision demands, the internal stress should be reduced or even avoided. According to the coupling method of multi-physical fields, the curing process and the process-induced deformation of composite laminates were simulated systematically in this work. The influencing factors are classified into two categories: matrix-dominated and fiber-dominated. The former category consists of curing shrinkage and reaction heat. Reaction heat influences the curing deformation through affecting the temperature and curing degree fields; however curing shrinkage has a direct impact on the strain. The latter one consists of ply orientation and fiber volume fraction, which influence the curing deformation by affecting the mechanical properties of the composite laminates. This study is helpful for understanding the relationship among the thermal, chemical, and mechanical behaviors.
Impact of Chamber Length, Slot Width, and Part Thickness for Tapered Resin Injection Pultrusion
Authors: Mitlapalli R. , Roux J.A. , Jeswani A.L.
Published: September 2018

Injection pultrusion is a continuous process of manufacturing composites with a constant cross-section by pulling a fibre matrix through a resin injection chamber and into a heated die where the resin is subsequently cured. The objective of the present study is to obtain a quality composite by achieving complete resin wet-out of the fibre reinforcement. Complete wet-out depends on processing parameters and design parameters. This work deals with the impact of two design parameters (injection slot width and composite part thickness) on the minimum resin injection pressure required to achieve complete wet-out along with the associated chamber interior pressure for various resin injection chamber lengths with different tapering angles.
Electrospraying Fabrication and Characterization of Low Molecular Weight Poly(vinyl alcohol)/Silver Composite Nanospheres for Antibacterial Applications
Authors: Park Jae Hyeung , Park Sung Min , Kim Young Hwa , Choi Jae Young , Islam Md. Shahidul , Oh Weontae , Deng Yulin , Kim Young Hun , Yeum Jeong Hyun
Published: September 2018

Low molecular weight poly(vinyl alcohol) (LMW-PVA)/silver (Ag) composite nanospheres were prepared using an electrospraying technique by controlling the concentration of PVA solution. Since PVA is water-soluble and biocompatible, it is one of the best polymers for preparation of antibacterial materials. The composite nanospheres were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and antibacterial activity measurement. The LMW-PVA/Ag composite nanospheres had ∼350 nm average diameter and showed powerful antibacterial ability.
Induction Heating of Thermoplastic Materials by Particulate Heating Promoters
Authors: Bayerl Thomas , Schledjewski Ralf , Mitschang Peter
Published: September 2018

Induction heating is a fast and selective heating method, which can also be applied to polymeric materials, even though these materials do not offer the required electrical or ferromagnetic properties. To compensate for this deficiency, polymeric matrixes (high density polyethylene and polyamide 6) were compounded with various ferromagnetic and electrically conductive particles. The experimental series included induction heating experiments of compounds with different particle materials and variable filler grades at two distinct frequency levels (430 kHz and 2500 kHz). A mechanical characterization of the compounds was performed to identify the influence of the particles on matrix properties.

The heating experiments showed a significant temperature rise of the particle doped materials, when they were exposed to an alternating magnetic field. The temperature rise was observed with plates as well as with pellets. The heating effect was found to be dependent on the frequency and the particle material. The best results were obtained from ferromagnetic particles like iron and magnetite, whereas for example non-ferromagnetic carbon black could only be activated in pellet-shape at high magnetic field strength. To reach the melting temperature of the polymer within a maximum time frame of three minutes, the filler content of specific particles could be as low as 5 wt.%. The mechanical properties of the materials, such as tensile strength and stiffness were influenced only marginally, while the impact strength was reduced by the particles by up to 25%.
Thermal and Gas Barrier Properties of COC/SiO2 Nanocomposites
Authors: Ou Cheng-Fang , Shen Po-Hung
Published: September 2018

This study is performed primarily to investigate the effects of chemical modification on silica surface and the silica content on the thermal and gas barrier properties of a cyclo olefin copolymer (COC) matrix. The COC/SiO2 nanocomposites were constructed from COC and three species of SiO2 nanoparticles (AEROSIL A200, R805 and R974) with different organic groups, prepared by solution blending. The thermal properties of the composites were studied by DSC and TGA. The gas barrier properties of the composites were characterized by use of a gas permeability analyzer. The glass transition temperature (Tg) and decomposition temperature (Td) of these composites increased obviously with the silica content ranging from 0.5 to 10 wt.%. The composite with 10 wt.% R805 exhibited the highest Tg, which was 14.1 °C higher than that of pure COC. The water and oxygen permeability decreased with increasing the content of SiO2. The composites with 10 wt.% R974 had the minimum values of water and oxygen permeability and were 32% and 36% lower than those of pure COC, respectively. The dispersion of these silica particles in the COC matrix was made by SEM and consideration was given to the relationship between the modified silica surface and the COC matrix, and thermal properties and gas barrier properties.
Screening the Viability of Roselle Graft-copolymers
Authors: Chauhan Ashish , Kaith Balbir
Published: September 2018

In this paper, graft-copolymerization of Hibiscus sabdariffa (Roselle) using methyl acrylate (MA) as principal monomer and 4-vinyl pyridine (4-VP) as secondary monomer, using ceric ammonium nitrate – nitric acid initiator system in binary vinyl monomeric mixture, has been reported. Different optimized reaction parameters such as temperature, time, initiator concentration, monomer concentration and pH were used to obtain the maximum graft yield and then to explore its change on properties and behaviour of the fibre. The graft copolymer were characterized by FTIR, SEM, XRD, TGA and DTA techniques and evaluated for swelling behaviour, chemical resistance, moisture absorbance and dye-uptake behaviour, keeping in view the use of these advanced graft copolymers for scientific and industrial application.
Preparation of Nanocomposites Based on LDPE/Perlite: Mechanical and Morphological Studies
Authors: Sahraeian R. , Hashemi S. A. , Esfandeh M. , Ghasemi I.
Published: September 2018

Perlite nano-particles were prepared through a mechanical grinding process and surface-modified by poly(methyl hydrogen siloxane) (PMHS). Nanocomposites based on low-density polyethylene (LDPE) and different compositions of treated and untreated nano particles were prepared via melt mixing of the ingredients on a co-rotating twin screw extruder. Laser light-scattering (LLS) was used to analyze the mean particle size of the nano perlite while Fourier-transform infrared spectroscopy (FTIR) was employed to investigate surface modification of the particles. Scanning electron microscopy (SEM) was used to evaluate the dispersion status of the nano particles in the polymer matrix. Results indicated a relatively good dispersion of the particles (50-500 nm in size) within the LDPE matrix. Mechanical measurements showed remarkable increases in tensile strength and modulus of the nanocomposites containing surface modified perlite, compared to the neat polymer. Also, flexural strength and modulus were increased with increasing nano perlite, while impact properties were reduced.
Dynamic Mechanical Characterization of the Crosslinked and Chain-extended HTPB Based Polyurethanes
Authors: Ahmad Nadeem , Khan M.B. , Ma Xiaoyan , Ul-Haq Noaman , Ihtasham-ur-Rehman
Published: September 2018

The viscoelastic response of two different polyurethane (PU) systems (crosslinked and chain-extended) based on hydroxyl terminated polybutadiene (HTPB) were analyzed and compared. The PU elastomers were fabricated by reacting HTPB with isophorone diisocyanate. A tri-functional alcohol (1,2,6 hexanetriol) and a bi-functional aliphatic diol (1,4 butanediol) were used as the crosslinking agent and the chain extender respectively. Hydrogen bonding between the hard segments is indentified by the IR spectroscopy. The segregation of these segments was manifested by dynamic mechanical analysis at characteristic frequency over a wide range of temperature. The intensity and temperature location of the relaxation peaks was identified and discussed. The phenomenon of viscous dissipation was evaluated by recording the viscoelastic parameters as a function of temperature across a series of frequencies. The results obtained indicate that the chain-extended polymer is phase segregated and more sensitive to temperature rise via viscous dissipation as compared to crosslinked polymer. Both the polymers showed similar glass transition temperature (Tg) and characteristic relaxation times. Master curves for the polymer systems investigated are produced and discussed.
Characterization of Biocompatible Scaffolds Based on Gelatin and Hyaluronic Acid for Fibroblasts Culture
Authors: Zhou Zhihua , Yang Zhongmin , Huang Tianlong , Liu Lihua , Liu Qingquan , Zeng Wennan , Cao Dafu , Ma Songjiang
Published: September 2018

Gelatin/hyaluronic acid (Gel/HA) scaffolds were prepared by using the freeze-drying method after crosslinking with 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide (EDC). The porous structure was characterized by scanning electron microscopy (SEM), and the wettability of Gel/HA film was also studied by measuring their contact angle. The biological behaviour of the scaffolds was analyzed by studying the cell behaviour using a fibroblast cell line and standard biological MTT test. The results showed that the scaffold had an inter-connected pore structure with a sufficient pore size for use as a support for the growth of fibroblasts. The contact angle decreased with increasing HA content, whereas the cell attachment and proliferation improved with decreasing HA content. Confocal laser scanning microscopy (CLSM) demonstrated a normal cell distribution and proliferation on the porous Gel/HA scaffolds.
Nickel–titanium shape memory alloy mechanical components produced by investment casting
Authors: de Brito Simões Jackson , de Araújo Carlos José
Published: September 2018

This work aimed to produce mechanical components of nickel–titanium shape memory alloys using investment casting processes. Then, in order to validate processing, different designs of nickel–titanium shape memory alloy components as staple implants, Belleville springs, meshes, helical springs, screws and hexagonal honeycombs were produced and submitted to thermal and mechanical characterization. Thermoelastic martensitic transformation of the nickel–titanium shape memory alloy parts was determined by differential scanning calorimetry and electrical resistance with temperature, while the superelastic behaviour was verified by cyclic tensile and compression tests. It has been demonstrated that the employed investment casting processes are suitable to manufacture nickel–titanium shape memory alloy mechanical components with simple and complicated designs as well as functional properties related to phase transformation and superelasticity.
Predictive Validity of Student Risk Screening Scale—Internalizing and Externalizing (SRSS-IE) Scores in Elementary Schools
Authors: Lane Kathleen Lynne , Oakes Wendy Peia , Cantwell Emily D. , Common Eric A. , Royer David J. , Leko Melinda M. , Schatschneider Christopher , Menzies Holly Mariah , Buckman Mark Matthew , Allen Grant Edmund
Published: September 2018

In this article, we examined predictive validity of Student Risk Screening Scale—Internalizing and Externalizing (SRSS-IE) scores for use with elementary-age students ( N = 4,465) from 14 elementary schools. Results indicated elementary school students with high levels of risk according to fall SRSS-IE scores—especially those with externalizing behaviors—were more likely to have lower oral reading fluency scores, lower Measures of Academic Progress (MAP) reading scores, more nurse visits, and more days spent in in-school suspension compared with students at low risk for externalizing or internalizing behaviors. Educational implications, limitations, and future directions are presented.
Long-term results after primary intraocular lens implantation in children with juvenile idiopathic arthritis–associated uveitis
Authors: Kulik Urszula , Wiklund Anna , Kugelberg Maria , Lundvall Anna
Published: September 2018

Purpose:

To evaluate the long-term outcome after cataract surgery with primary intraocular lens implantation in children with juvenile idiopathic arthritis–associated uveitis.

Methods:

The medical records of all 24 children (34 eyes) with chronic juvenile idiopathic arthritis–associated uveitis who underwent cataract surgery between 1990 and 2013 were reviewed retrospectively. Primary intraocular lens implantation was performed in all patients.

Results:

Median age at diagnosis of uveitis in the first eye was 5.3 years (range: 2.7–9.4 years) and median age at the time of cataract surgery in the first eye was 9.7 years (range: 4.1–16.9 years). Postoperative follow-up time ranged from 1 to 23.1 years, with a median of 10.9 years. Best corrected visual acuity at the last follow-up was good (⩾20/40) in 65% of the eyes. Postoperatively, glaucoma developed in 8 eyes (24%), posterior capsular opacification and secondary membrane formation requiring surgery in 15 eyes (44%), macular oedema in 5 eyes (15%) and phthisis in 2 eyes (6%).

Conclusion:

This study shows a favourable visual outcome in most of the cases. Primary intraocular lens implantation may be considered in juvenile idiopathic arthritis–associated uveitis complicated by cataract in patients with well-controlled inflammation.
The silver lining of greying: Ageing discourses and positioning of ageing persons in the field of social health insurance
Authors: Van den Bogaert Sarah , Ceuterick Melissa , Bracke Piet
Published: September 2018

Contemporary ageing discourses and policies perceive being active as the key to a good later life and thereby focus on individual responsibility and self-care. Drawing on website articles and press releases of Belgian sickness fund agencies, this study analyses the ageing discourses and positioning of ageing persons of these organisations. A discourse analysis was performed using positioning theory to analyse how sickness fund agencies discursively construct the ageing process and position ageing persons, and to investigate how these positioning acts are related to sickness fund agencies’ roles as social insurer, social movement, social entrepreneur and private insurer. Our results reveal three storylines on ageing; ageing as a medical problem, ageing as a new stage in life and ageing as a natural life process. These storylines are applied to construct ageing and position ageing persons in different ways. Depending on their role, sickness fund agencies take on a different position drawing on these different storylines. We also show how these storylines reproduce the moral framework on how to age well and thereby disempower ageing persons. Our results underline the importance of multidimensional perspectives on ageing.
Informal use of restraint in nursing homes: A threat to human rights or necessary care to preserve residents’ dignity?
Authors: Øye Christine , Jacobsen Frode F
Published: September 2018

Use of restraint in nursing homes is highly controversial and fundamentally transgresses human rights and freedom of movement and choice. While different forms of formal restraint use in nursing homes are broadly delineated, the use of informal restraint is less understood. The aim of this article is to identify different kinds of informal restraint, and how staff use informal restraint under which circumstances. This article illuminates informal restraint use based on an ethnographic study in four nursing homes in the Western part of Norway. We have identified five different forms of informal restraint use which are as follows: (1) diversion of residents’ attention; (2) white lies; (3) persuasion and interpersonal pressure; (4) offers and finally (5) threats. These different forms of informal restraint are actions by staff against residents’ will, limiting residents’ freedom of movement and their personal preferences. In addition, we have identified ‘grey-zone restraint’ which comprises actions by staff towards residents which lie in-between formal and informal restraint. The use of informal restraint can be explained by institutional circumstances such as location, architecture and institutional collectivist constraints in relation to care work. Moreover, and paradoxically, informal restraint can be explained as a consequence of neo-liberal policies with establishment of extended premises for freedom of movement and practices of resident preferences in nursing homes. Informal restraint practices call into question whether these practices are compatible with fundamental human rights and the preservation of residents’ dignity.
When words become borders: Ingroup favoritism in perceptions and mental representations of Anglo-Canadian and Franco-Canadian faces
Authors: Bjornsdottir R. Thora , Yeretsian Simon , West Greg L. , Rule Nicholas O.
Published: September 2018

Language is critical to social identity, including nationality. However, some nations encompass multiple languages, raising questions about how their citizens perceive members of their national versus linguistic groups. We explored perceptions of Canadian nationality, which consists of two linguistic groups: Anglo-Canadians and Franco-Canadians. In Study 1, we used reverse correlation methods to visualize how Anglo- and Franco-Canadians mentally represent the faces of linguistic ingroup and outgroup members, and of Canadians in general. Structural similarity analyses and subjective ratings of the resulting images showed that both groups mentally represented Canadians as more similar to their own linguistic ingroup. In Study 2, Anglo-Canadians and Franco-Canadians rated photos of real Anglo- and Franco-Canadian targets. Both samples showed some ingroup favoritism when inferring their traits but only Anglo-Canadians could accurately differentiate group members. Differences between Anglo-Canadians and Franco-Canadians therefore extend beyond language, with linguistic groups impacting impressions before any words are spoken.
A 10-Year Retrospective Study of 490 Hip Fracture Patients: Reoperations, Direct Medical Costs, and Survival
Authors: Tiihonen R. , Alaranta R. , Helkamaa T. , Nurmi-Lüthje I. , Kaukonen J.-P. , Lüthje P.
Published: September 2018

Background and Aims:

Reoperations after operative treatment of hip fracture patients may be associated with higher costs and inferior survival. We examined the acute hospital costs, long-term reoperation rates, and survival of patients with a new hip fracture.

Materials and Methods:

A total of 490 consecutive new hip fracture patients treated at a single center between 31 December 2004 and 6 December 2006 were analyzed retrospectively. Fractures were classified according to Garden and AO. All medical records were checked manually. The costs of reoperations were calculated using the diagnosis-related groups (DRG)-based prices. Survival analysis was performed using the life-table method. The follow-up time was 10 years.

Results:

In all, 70/490 patients (14.3%) needed reoperations. Of all reoperations, 34.2% were performed during the first month and 72.9% within 1 year after the primary operation. The hemiarthroplasty dislocation rate was 8.5%, and mechanical failures of osteosynthesis occurred in 6.2%. Alcohol abuse was associated with a heightened risk of reoperation. The mean direct costs of primary fracture care were lower than the mean costs of reoperations (€7500 vs €9800). The mortality rate at 10 years was 79.8% among non-reoperated patients and 62.9% among reoperated patients.

Conclusions:

According to our hypothesis, the cost per patient of reoperation in acute care was 31% higher than the corresponding cost of a primary operation. Reoperations increased the overall immediate costs of index fractures by nearly 20%. One-third of all reoperations were performed during the first month and almost 75% within 1 year after the primary operation.
Relational ethics as enrichment of social justice: Applying elements of contextual therapy to social work
Authors: van der Meiden Jaap , Noordegraaf Martine , van Ewijk Hans
Published: September 2018

This article applies insights of the contextual theory and therapy, developed by Ivan Boszormenyi-Nagy, to the body of knowledge and practice of social work. Social work and contextual therapy share their focus on justice. In social work, it is mainly elaborated as social justice, placed in the discourse of politics and action. Contextual therapy however, elaborates justice as relational ethics; a fundamental element of human relationships, expressed in an innate tendency to care for each other. According to the contextual theory, evoking this reciprocal care enhances human wellbeing. Therefore, next to the focus on social justice on macro level, this article introduces a focus on relational justice on micro level. Relational justice aims at restoring and enhancing relationships within the family, with those who are relevant for the wellbeing of the family, and with the family’s context. A focus on relational justice encompasses a promising resource for human wellbeing, and a constructive framework for a contextual social work approach. Subsequently, applicable interventions from the contextual therapy, derived from a previously conducted qualitative research on the practice of contextual therapy, are tailored to the social work practice. Conclusively, this article states that justice within family relationships is an important element for successfully realizing of social justice.
Preparation and Evaluation of Thermally Depolymerized Natural Rubber in Rubber Compound Formulations
Authors: Cataldo Franco
Published: September 2018

Natural rubber was depolymerised into a viscous oil by a low temperature pyrolytic process. The preparation process is reported together with a H-NMR and FT-IR characterization of the resulting product. After the thermal degradation, natural rubber substantially retains its 1,4-polyisoprene structure although there are clear evidences about extensive cis-trans isomerization and chain scission phenomena.

Liquid natural rubber was tested as plasticizer in two rubber formulations. A natural rubber-based formulation and a natural rubber/styrene-butadiene blend were compounded with depolymerised natural rubber in place of the traditional plasticizer based on aromatic extracts. The cure kinetics, the mechanical and dynamic properties of the compounds were tested and discussed.

The performances offered by depolymerised natural rubber as plasticizer were satisfactory in comparison to aromatic oil and surprisingly it was found that the natural rubber oil gives higher hysteresis in comparison to a traditional aromatic extract.

The environmental impact of the results of the present study has been emphasised.
Effect of Regenerated Carbon-Black on a Bias Tyre Tread Cap Compound
Authors: Bandyopadhyay S. , Mandal N. , Agrawal S.L. , Dasgupta S. , Mukhopadhyay R. , Deuri A.S. , Ameta Suresh C.
Published: September 2018

Carbon black, which is an important ingredient in a tyre, was regenerated from waste automobile tyre tread component. The regenerated black was characterised by different chemical and analytical methods and the properties were compared with a virgin N330 black. The regenerated black was also evaluated in a bias lug type tyre tread cap compound. It was observed that compared to the virgin black the regenerated black exhibited marginal inferior physico-mechanical properties. A linear trend of decrease in properties on increasing the dosage of the regenerated black was also observed.
7-Isopenthenyloxycoumarin, Arctigenin, and Hesperidin Modify Myeloid Cell Leukemia Type-1 (Mcl-1) Gene Expression by Hormesis in K562 Cell Line
Authors: Kafi Zahra , Cheshomi Hamid , Gholami Omid
Published: September 2018

Hormesis is a new concept in dose–response relationship. Despite of traditional dose–response curves, there is a low-dose stimulation and a high-dose inhibition in this case. Hormesis effect in apoptosis induction/inhibition by natural compounds is reported previously. Here, we searched this effect for myeloid cell leukemia type-1 (Mcl-1) gene expression by phytochemicals 7-isopenthenyloxycoumarin (7-IP), arctigenin (Arg), and hesperidin (Hsp). For this purpose, first we tested the cytotoxicity of various doses of these compounds against K562 leukemia cell lines for different times by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. After that we explored the effect of various doses of these phytochemicals on Mcl-1 gene expression for different times by real-time polymerase chain reaction method. We found that these phytochemicals have cytotoxicity against K562 cell line. Hesperidin is the most cytotoxic agent. We also found that these natural compounds have hormetic effect on Mcl-1 gene expression. The hormetic model in Mcl-1 gene expression is overcompensation stimulation. This phenomenon is reported for the first time. We conclude that 7-IP, Arg, and Hsp are cytotoxic against K562 cancerous cells and induce/inhibit Mcl-1 gene expression by hormesis dose–response relationship.
Optimization design of powertrain mounting system considering vibration analysis of multi-excitation
Authors: Xu Xiangyang , Su Chengyun , Dong Peng , Liu Yanfang , Wang Shuhan
Published: September 2018

The stiffness of mounting system determines the vibration isolation ability of the transmitted path, which is the key factor that affects the vibration and noise of vehicle. In order to improve the vibration isolation ability of the powertrain mounting system, considering the powertrain of front wheel drive car as the research object, the vibration decoupling rate and its corresponding frequency of the powertrain mounting system are analyzed by rigid body dynamics and energy method. The correctness of the calculation program with energy method has been verified by calculated vibration decoupling rate. Based on the genetic algorithm and the fusion robustness analysis, the decoupling rate and modal frequency of the mountings in all directions are considered as the objectives; the stiffness of the three mountings is optimally designed. Through multi-excitation of three methods and vehicle test, the vibration response characteristics and the vibration noise test data of the optimization stiffness are compared and the results shown that the vibration isolation performance has been significantly improved more than 10%. An integrated design method of stiffness optimization design and vibration analysis in vehicle PMS is formed, which has theoretical and practical value, and can reduce vehicle vibration and noise.