bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing and Mechanical Properties of Strands of Liquid Crystalline Copolyester and Copolyesteramide
Authors: Kyotani Mutsumasa , Kaito Akira , Nakayama Kazuo
Published: April 2023

Extrusion moulding behaviour, mechanical and morphological properties of thermotropic liquid crystalline copolyester (LCP-A) and copolyesteramide (LCP-B) strands were investigated using a co-rotating twin-screw extruder, tensile testing, x-ray diffraction measurements, and scanning electron microscopic observation. Extrusion pressure and torque of LCP-B strands were larger than those of LCP-A strands under the same extrusion conditions, reflecting a difference in the apparent melt viscosity of the two polymers. The LCP-B strands obtained in this study had more homogeneous diameters, as compared with the LCP-A strands. The irregularity in diameter of the LCP-A strands tended to become smaller with increasing the length-to-diameter ratio (l/D) and output flow rate. The molecular orientation of LCP-B strands rose rapidly with draw ratio and reached almost a plateau at a much lower one, whilst that of the LCP-A strands became slowly higher with draw ratio. The tensile modulus and strength of LCP-B strands increased gradually with a draw ratio, even after the molecular orientation of the strands levelled off. The effect of the draw ratio on the molecular orientation and the mechanical properties of the strands was discussed from a morphological point of view.
Acoustic Emission Characteristics and Fracture Properties of Epoxy Moulding Compound Filled with Spherical Silica Particles
Authors: Ohta Mutsuko , Nakamura Yoshinobu , Hamada Hiroyuki , Maekawa Zen-ichiro
Published: April 2023

The effects of particle size and surface treatment on the acoustic emission (AE) characteristics and the tensile strength of epoxy resin filled with spherical silica particles were studied. The particle content was 70 wt%. Four kinds of spherical silica particles having different mean sizes in the range from 6–31 μm were used. In order to improve and decrease the adhesion of the interface between particle and epoxy matrix, the particles were treated with silane coupling (A) and silane decoupling (B) agents, respectively. The A- and B-treated particle-filled systems were compared with the untreated particle-filled system. As the particle size increased, the tensile strength decreased and AE events increased. The tensile strength was higher in the order of the A-treated > the untreated > the B-treated systems. Fewer AE events were generated in both A- and B-treated systems than in the untreated system. Scanning electron microscopic observation of fractured surfaces was carried out to clarify the reason of the above results.
Structural Relaxation of Poly(methyl methacrylate)
Authors: Avramov I. , Vassilev Ts.
Published: April 2023

The kinetics of structural, relaxation of poly(methyl methacrylate) (PMMA) is studied and it is shown that the activation energy of the process depends on the structural temperature Tf. A new method is proposed allowing the measurement experimentally of how the activation energy decreases with increasing Tf.

The dependence of the glass transition temperature Tg on the heating rate q+ is investigated for samples that were previously cooled down at a rate q = 12.5 K/min. It is found that the activation energy for structural relaxation is E = (250 ± 10%) kJ/mol at T=386K. On the other hand, the value of the apparent ”activation energy” obtained from the dependence of the structural temperature Tf on the cooling rate q- is considerably higher. This is an indication that the activation energy depends on Tf. We found that the temperature dependence of the activation energy of PMMA in the vitrification interval is E(T) = 250–670* (386/T-1) kJ/mol.
Numerical Evaluation of the Influence of Loading Rate on the Interlaminar Fracture of Graphite/Epoxy
Authors: Chiu W.K. , Jones R.
Published: April 2023

The fracture toughness of materials that exhibit limited yielding at the crack tip is often characterised by evaluation of the “far-field” J integral. However, Carlsson et al(7) have shown that such “far-field” parameters may be less than ideal for composite materials where the crack tip in the matrix material undergoes extensive yielding. This paper investigates this proposition and presents the results of a numerical evaluation into the use of a near-tip energy integral, the so called T* parameter, for evaluating the fracture toughness of composite materials. Here attention is focused on both the near-tip fracture parameter and on load history effects.
Moisture Absorption and its Influence on the Tensile Properties of Glass-Fibre Reinforced Polyamide 6,6
Authors: Akay M.
Published: April 2023

The equilibrium amounts of moisture absorbed by a range of grades of glass fibre reinforced polyamide 6,6 were approximately proportional to the weight fraction of the polymer. However, the moisture diffusivity was found to be also a function of variations in specimen preparation and microstructure. The diffusivities of the moulded composite specimens indicated a law of mixtures relationship; whereas those with machined edges differed significantly.

Moisture-induced deterioration of tensile strength was most severe up to 1.5% and 3% by weight moisture contents for the glass-fibre containing and unfilled polyamide 6,6, respectively. Moisture ingress, as would be expected, resulted in increased elongations to failure for the unfilled polymer but caused almost no variation in the elongation behaviour of the reinforced polymer.
Thermostabilisation of Polyisoprene by Phenol Grafting in Carbene Synthesis
Authors: Davydov E.Ya. , Pustoshnyi V.P. , Vorotnikov A.P.
Published: April 2023

The comparison between traditional and grafted antioxidants shows that grafted antioxidants has qualitative advantages.

DTBP produces the most promising results in the study. The results suggest that hindered phenols grafted by carbene synthesis on macromolecules will stabilise P.I. and other elastomers.
Preparation of New Polymeric Active Coatings for Vascular Applications, Based on Biocompatible Acrylic Systems with Anti-Inflammatory Components
Authors: Gallardo Alberto , Roman Julio San
Published: April 2023

Data on the preparation of hydrophilic polymeric systems based on copolymers of 2- hydroxyethyl methacrylate H, with new acrylic derivatives of 4-methoxyphenylacetic acid or Ibuprofen (drugs widely used as analgesic and non-steroidic anti-inflammatory agents) are presented. The copolymer systems prepared with 5–20% of the pharmacologically active acrylic derivative form hydrophilic films when a solution of the prescribed concentration is applied as a coating of biomaterials used for the preparation of vascular implants like knitted or woven meshes of Dacron or small-diameter vascular grafts of Goretex. After evaporation, thin films with good adhesion to the porous surface are obtrined, and the polymeric coating remains in standard flow conditions. The absorption of water after immersion of films in a buffered solution at pH = 7.2 was followed gravimetrically and the swelling behaviour at the equilibrium was analysed considering the average composition of the acrylic copolymer systems used in the present work.
Delamination Failure in Unidirectional Carbon Fibre/Epoxy under Mixed Mode Loading
Authors: Singh S. , Partridge I.K.
Published: April 2023

Delamination resistance of Fiberite's IM7/977-1 carbon fibre/epoxy composite was evaluated under Mode I, mixed Mode I/Mode II in the ratio of 4/3, and Mode II loadings. The need for Mode I pre-cracking of the UD composite beam prior to the actual fracture test was demonstrated. The fracture toughness data were found to fit a simple power law failure criterion and a physical meaning for the fitting parameter was suggested. Fractographic studies were carried out by SEM examination near the crack initiation areas of the fracture samples and illustrated the gradual change in the micromechanisms of failure as the loading mode changed from crack opening to forward shear.
Correlation between the State of Cure of Unsaturated Polyester Coatings and Their Resistance to Ethanol
Authors: Haffane N. , Benameur T. , Granger R. , Vergnaud J. M.
Published: April 2023

The correlation between the state of cure of an unsaturated polyester coating and its resistance to ethanol at room temperature is studied. The heat generated by the remainder of the cure reaction at a given time as a fraction of the total heat generated is called the state of cure. Sheets with various states of cure ranging from 75 to 95% were prepared and put in contact with an ethanolic solution at 95% ethanol. The process of ethanol absorption is controlled by transient diffusion with a constant diffusivity. A statement is obtained: the higher the state of cure, the lower the amount of ethanol absorbed and the lower the diffusivity.
Control of Additives
Authors: Merkx Stephan
Published: April 2023

The European Commission has been working on the harmonization of food contact regulations of the individual EU Member States for over two decades. Harmonization has been achieved in the area of regenerated cellulose film and ceramics and for some aspects of plastics. A considerable amount of food contact legislation is still to be formulated and there is enough reason to look back at the achievements in the field of Community food contact legislation, and to learn from the experience gained so far. The legislative system for plastics food contact materials as it has been developed so far is becoming very sophisticated and it must be feared that it is going to lose touch with reality. Regulations are getting tougher and more specific whilst the quality of plastics food contact materials is continuously improving as a result of constant progress in plastics technology. This paper describes the position of additives in plastics - an area still to be harmonized - and gives recommendations on how future Community food contact legislation on additives in plastics could be formulated taking into account aspects of practicability and enforceability, without compromising public health.
Diffusion of Aromatic Liquids into Blends of Ethylene-Propylene Copolymers and Isotactic Polypropylene Membranes
Authors: Aminabhavi Tejraj M. , Phayde Hemant T.S. , Ortego J. Dale
Published: April 2023

The molecular transport of benzene, toluene, p-xylene, ethylbenzene, chlorobenzene, 1,2-dichlorobenzene, and mesitylene into miscible polymeric blends of ethylene-propylene random copolymer and isotactic polypropylene has been investigated at 25, 40, 55, and 70°C. For all liquids, the solvent transport rate, equilibrium uptake and degree of penetrant overshoot are influenced by the nature of the solvent molecules and by the temperature. Sorption- desorption-resorption-redesorption (S-D-RS-RD) experiments have been carried out to determine the sorption equilibrium and diffusion coefficients. These S-D-RS-RD experiments are a convenient way of studying the weight loss, if any, during the long-term solvent exposure, which may be associated with the release of residuals. The activation parameters for diffusion, permeation, and sorption have been obtained. The concentration dependence of diffusivity has been studied. The morphology of the membrane material has been investigated using XRD and scanning electron microscopy.
Impact Performance of a Woven Fabric CFRP Laminate
Authors: Kim J.K. , Leung L.M. , Lee S.W.R. , Hirai Y.
Published: April 2023

Low velocity instrumented impact, ultrasonic C-scan and compression-after-impact tests have been employed to assess the damage resistance and damage tolerance of carbon fibre-epoxy matrix composites (CFRPs). The potential advantages of using woven fabrics, compared to cross ply unidirectional fibres, in impact performance of carbon fibre composites were examined. The laminates had two distinct fibre configurations and similar static in-plane mechanical properties in the undamaged state. The characteristic impact loads and the corresponding absorbed energies were used to evaluate the initial damage resistance of the laminates. The residual strengths, measured from the compression-after-impact tests, were analysed to predict the threshold energy and the threshold damage area, which are a measure of the damage tolerance of the laminates.
Tensile Properties of Short Glass Fibre Reinforced Polycarbonate
Authors: Ho Kye-Chyn , Hwang Jiun-Ren , Doong Ji-Liang
Published: April 2023

The present study analyses the tensile properties of polycarbonate and of polycarbonate reinforced with 20 and 30 wt.% short glass fibre. The specimens were prepared under various injection moulding conditions, such as filling time, melting temperature and mould temperature. The fracture mechanism was examined by scanning electron microscopy. The results indicated that the polycarbonate reinforced with 30 wt.% short glass fibre shows the highest strength, together with the highest Young's modulus and yield strength. The ultimate strength of the 30 wt.% reinforced-material is approximately 20% higher than that of the 20 wt.% reinforced equivalent and about twice as high as that of unreinforced polycarbonate. Also, the ultimate strength measured in the direction of injection flow was about 10% higher than that measured normal to it. The optimum injection moulding conditions for ultimate strength are: filling time 5 s, melting temperature 290°C and mould temperature 80°C. The ranking of the ultimate strength is strongly related to the layer thickness in which the fibres align with the tensile direction. The higher the fibre content, the higher the strength. The striations, cleavage and tearing fracture mechanisms dominate in unreinforced polycarbonate when the tensile stress was parallel with the flow direction, while splits and secondary cracks were found when the tensile direction was perpendicular to the flow direction. The fibre pull-out, fibre breakage and striations are the major fracture mechanisms in short glass fibre reinforced polycarbonate.
In-Line Quality Monitoring of Pultruded Profiles using Dielectric Measurements
Authors: Methven J.M. , Katramados Y.
Published: April 2023

A cylindrical microwave cavity operating in the TM010 mode at 2450MHz has been incorporated in a Microwave Assisted Pultrusion (MAP) line to monitor continuously the quality of a cylindrical 6.0mm diameter solid rod for use as a tension member in optical cables. The cavity is coupled to a HP 8753C vector network analyser and measures in realtime the quality factor and shift in resonant frequency of the cavity as the profile passes through it en route to the haul-off. The measurements are used to calculate the dielectric constant and loss tangent of the profile. The results can be associated with degree of cure of the profile and may be used to prescribe a process window where quality is related directly to line speed, power input, etc. The technique could be used as the basis of a feedback control system in pultrusion.
Mechanical Properties of Non-Woven Glass Fibre Composites
Authors: Kang Tae Jin , Lee Sung Ho
Published: April 2023

The mechanical and impact resistant properties of needle punched non-woven glass fibre composites have been studied. The non-woven composites showed an improvement in mechanical properties with increasing fibre entanglements caused by needle punching. At the same time fibre damage during the needle punching process caused an impairment of performance. Tensile, bending, impact, compression after impact and mode-I tests were performed to investigate the effect of punching density on the mechanical properties. The tensile strength increased with punching density, but the tensile modulus, absorbed impact energy and bending properties decreased. The non-woven composites showed more isotropic mechanical properties with increasing punching density. The energy absorption capability under repeated impact showed a maximum at the low range punching density. The higher the punching density the smaller was the reduction in compression strength after impact. The mode-I interlaminar fracture toughness (GIc) increased with punching density due to the through-the-thickness reinforcing fibres. It was three times as tough as the woven laminate composites. At the optimum punching densities, non-woven composites showed profoundly improved mechanical and impact properties compared with woven laminate composites.
Representation of Local Stiffness Variation in Textile Composites
Authors: Weissenbach G. , Limmer L. , Brown D.
Published: April 2023

The high degree of heterogeneity in fabric composite materials is identified as a major problem in their structural analysis. A procedure is proposed to represent the material stiffness variation as a function of the spatial coordinates by using splines. The stiffness variations are exemplified using a plain weave composite. The role of this stiffness function is to facilitate the calculation of the averaged material stiffness tensor for arbitrary domains in the form of finite elements. Once this exercise has been completed for a meshed part, a finite element analysis can be performed in order to obtain information on a local level. The facility with which the averaged material stiffness tensor over an element can be calculated is not only important in terms of underpinning mesh refinement and adaptive meshing, but, more importantly, to conduct a more correct and precise, i.e. material adaptive, stress analysis.
Experimental Methods for Estimation of Stabiliser Efficiency
Authors: Gurvich Ya. A. , Arzamanova I.G. , Zaikov G.E.
Published: April 2023

An extensive review of (mainly Russian) research in stabilisers for important commercial organic high polymers is presented. Model systems for estimating the efficiency of stabilisers are discussed. Two kinds can be recognised: (a) polymer-based, (b) others. The review also considers examples of the many techniques used in these model reaction experiments and discusses structure-activity relationships.
The Properties of Crosslinked Foams Produced from Metallocene Polyolefins
Authors: Eaves David
Published: April 2023

A unique foaming process is briefly described and the properties of polyolefin foams produced by this process are reviewed. The influence of parameters such as foam density, crosslink level and cell structure are discussed, and in particular the effect of polymer type is examined. Foam grades based on metallocene polyolefins have recently been introduced, and the properties of these materials are compared with those of foams based on other polymers.
Reactive Compatibilisation of Polymer Blends of Poly(butylene terephthalate) and Poly(ε-caprolactam): Effect of the Addition of 4,4′-Biphenol
Authors: Xiaochuan Zhu , Shibata Mitsuhiro , Yosomiya Ryutoku
Published: April 2023

Improvements in the compatibility and mechanical properties of blends of poly(butylene terephthalate) (PBT) and poly(ε-caprolactam) (PA6) were sought by the addition of 4,4′-biphenol as a reactive compatibiliser. As a result, when 4,4′-biphenol 6 phr was added to the PBT/PA6 (weight ratio: 60/40) blend, its compatibility and flexural strength and modulus were considerably improved. Electron spectroscopic for chemical analysis of the PBT/PA6/4,4′-biphenol blend suggested the reaction of the amide group of the PA6 with the biphenol.
Damping of Patched Structures Subjected to Acoustic Fatigue: A Numerical Study
Authors: Chiu W.K. , Galea S.C. , Callinan R.
Published: April 2023

This numerical study seeks to evaluate a set of reinforcement/damping treatment options to alleviate the acoustic fatigue damage of the nacelle panel of the F/A-18 aircraft. This study focuses on the use of constrained layer damping to increase the structural loss factor in the nacelle region in a bid to reduce the incidence of acoustic fatigue. The findings of this report show that where add-on damping material is to be implemented on a repair/reinforcement, orthotropic material, (e.g. boron/epoxy), is a more appropriate material to use as a repair/reinforcement material than isotropic material, e.g. aluminium. In addition, the results presented in this paper revealed that boron/epoxy laminate can be used as an alternative constraining layer for the damping treatment in regions of intense acoustic excitation.
Synthesis of Poly(Vinyl Acetate) - Chitin Graft Copolymers as a Base for Chitosan-Polyf(Vinyl Alcohol) Ion Exchangers
Authors: Abdel-Mohdy F.A. , Waly A. , Ibrahim M.S. , Hebeish A.
Published: April 2023

Graft polymerization of vinyl acetate with chitin was effected using either the ferrous ion/hydrogen peroxide redox system or gamma radiation for initiation. The polymerization reaction was studied with respect to graft yield, homopolymer yield and total conversion. Results imply that the redox initiation is superior to irradiation, since it gives a much higher graft yield. Conversion of chitin-g-poly (vinyl acetate) to chitosan-g-poly (vinyl alcohol) was expedited using 48% sodium hydroxide at 130°C for 3 h. The use of chitosan-g-poly (vinyl alcohol) as an ion-exchanger was examined. The capacity of this ion exchanger to adsorb heavy metal ions such as cupric and dichromate, as well as some dyestuffs was also studied. The results indicate that the copolymer under investigation is a potentially powerful ion exchanger that can be employed for heavy metals and dyestuff removal from wastewater effluents.
Kinetics of Formation of Heterocyclic Polymer Networks. 3. Catalyst Effect
Authors: Privalko V.P. , Kramarenko V.Yu. , Sokol V.L. , Karateev A.M.
Published: April 2023

Non-isothermal trimerization kinetics of 1,6-hexamethylene diisocyanate (HMDI) in the reaction mixture with epoxy resin (ER) at a fixed ratio HMDI/ER = 85/15 (mass) catalyzed by differential concentrations of triethylene amine (TEA) was studied by differential calorimetry at four heating rates. In contrast to the simple single-step models, the isoconversional approach proved to describe quantitatively the reaction kinetics over the entire range of conversions, The apparent activation energies of the curing process and the corresponding pre-exponential factors tended to decrease smoothly, the higher the conversion, whereas a definite excess of the amine component turned out to be necessary to arrive at the maximum reaction rate.
Transport Behaviour of Aliphatic Hydrocarbons through Dynamically Crosslinked Natural Rubber/Polystyrene Blends
Authors: Asaletha R. , Kumaran M.G. , Thomas Sabu
Published: April 2023

The transport behaviour of aliphatic hydrocarbon liquids through crosslinked natural rubber/polystyrene blends has been studied in the temperature range of 28–58°C. Natural rubber/polystyrene blends were dynamically crosslinked using different vulcanising systems, i.e., sulphur, peroxide and a mixed system consisting of peroxide and sulphur. The sorption behaviour of the above systems was analysed in three different solvents viz., mineral turpentine, diesel and petrol. The effects of various vulcanising systems, temperature, blend composition and solvents on different sorption parameters were studied. The mechanism of transport showed anomalous behaviour in all the systems. The sorption data have been used to estimate the activation energy, the enthalpy and entropy of sorption, diffusion coefficient and polymer-solvent interaction parameter. Arrhenius activation parameters for diffusion, permeation and sorption have been estimated. The first and second order kinetic equations were used to study the sorption kinetics. Finally, the experimental results were compared with theoretical models.
Effect of Particle Shape on the Mechanical Properties of Particle-Filled PVC
Authors: Nakamura Yoshinobu , Okabe Seiji , Yoshimoto Norihisa , Iida Takeo
Published: April 2023

The effects of particle volume fraction, size and shape on the yield stress of a particle-filled ductile polymer were investigated. For this purpose, 10–50 parts of glass beads ranging in size from about 50 to 200 μm were mixed with 100 parts of poly(vinyl chloride) (PVC) as a ductile matrix using a mixing roll, and tensile tests were carried out. The yield stress decreased considerably with an increase in filler content, but only decreased slightly with an increase in particle size. To clarify the effect of particle shape, agglomerates of the glass beads were prepared by treating them with poly(vinyl alcohol), which has poor compatibility with the PVC matrix. It was confirmed by scanning electron microscopy that the agglomerates, consisting of a few beads on the average, were dispersed in the matrix. The decrease in the yield stress was smaller in the agglomerate-filled resin than in the original bead-filled resin. The shape of the particles seems to be important in moderating the decrease in the yield stress of particle-filled ductile polymers.

The authors are grateful to Mr. Toshiki Takamatsu, New Metals and Chemicals Co., Ltd., Tokyo, Japan for measuring the particle size distributions and for his useful suggestions, and also to Bihoku Funka Kogyo Co., Ltd., Okayama, Japan for the CaCO3 particles.
Thermorheological and Mechanical Properties of Polysulphone/Poly(ethylene terephthalate) Blends
Authors: Baranov A.O. , Dubnikova I.L. , Kompanietz L.V. , Turusov R.A. , Prut E.V.
Published: April 2023

An experimental investigation of the thermal, rheological and mechanical behaviour of polysulphone (PSF) / poly(ethylene terephthalate) (PET) blends having different blend compositions has been conducted. It was shown that the thermorheological and mechanical properties of the blends are associated with their structure and phase morphology. The observed good agreement between the experimental results and the glass transition temperatures calculated from the Fox equation, and the melting temperatures calculated from the Nishi-Wang equation, indicates a partial compatibility and the formation of homogeneous amorphous areas in PSF/PET blends. It was found that an addition of PET (up to 15 wt.%) to PSF results in a significant decrease in the melt viscosity, and a simultaneous improvement in the mechanical properties of PSF; the Young's modulus values of all the compositions are higher than the corresponding values computed from the proportional additivity rule. Thus, the flow and mechanical characteristics of the PSF/PET systems are governed mainly by the phase structure and morphology of the blends.
A Study of Blends of Poly(ethylene naphthalate) with a Liquid Crystalline Polyester
Authors: Shibata Mitsuhiro , Zhu Xiaochuan , Yosomiya Ryutoku
Published: April 2023

Blends of poly(ethylene naphthalate) (PEN) and a liquid crystalline copolymer based on p-hydroxybenzoate and ethylene terephthalate, known as Novaccurate E310 (E310), were studied. The effect of compatibilizers on the mechanical properties and morphologies has been investigated. The mechanical properties of the PEN/E310 (weight ratio 80/20) blend were considerably improved on the addition of 4,4′-dihydroxy-3,3',5,5′-tetramethyldiphenyl ether (TM-DPE), in agreement with the improvement in compatibility shown by the SEM analysis. The gel permeation chromatography analysis showed that most of the TM-DPE in the PEN/E310/TM-DPE blend does not react. The IR spectral analysis suggested that the hydrogen bonding between the hydroxyl group of TM-DPE and the ester group of PEN and/or E310 acts beneficially for compatibilization.
Fracture Analysis of Delamination Failure in Angle-Ply Elastomer Composites
Authors: Pidaparti R.M.V. , Kakarla V.
Published: April 2023

Fracture analysis of delamination type cracks in angle-ply elastomeric laminates was carried out using three-dimensional finite element analysis. The fracture parameter, tearing energy/J-integral that characterizes delamination failure in elastomer composites was computed from the finite element results of stresses and strains, and compared with existing analytical results using three different methods. The results obtained were validated with existing analytical methods in the literature. Numerical results of stress distributions and J-integral values are presented for various cord orientations and crack sizes. The results presented illustrate that cord-orientation and crack size have a strong effect on the values of tearing energy/J-integral. The results of the stress distributions and J-integral should help to improve our understanding of delamination type failures in elastomeric composite laminates.
New Evidence Supporting the Interfacial Model of Electrically Conductive Polymer Composites. 3. Morphological Study of Polyaniline-Poly(ethylene-co-vinyl acetate) Composites
Authors: Tsanov Tihomir , Gospodinova Natalia , Mokreva Pavlina , Terlemezyan Levon
Published: April 2023

A detailed study of the morphological features of polyaniline-poly(ethylene-co-vinyl acetate) (PANI-EVA) composites is presented. It is shown that their microstructure consists of highly ordered electrically conductive PANI paths embedded in the insulating EVA matrix. Long fibrils of PANI and interconnected fractal-like networks were also observed. It was found that the size of the primary PANI particles was ca. 5–10 nm. A spontaneous flocculation of these particles contributed to the formation of conductive pathways at extremely low percolation thresholds (Φc) (loading level ca. 0.005 wt. fraction). The sizes of the PANI domains varied during storage of the films and a key property of the conductive constituent (the PANI phase) was observed, namely a tendency for its solid state rearrangement. This PANI self-organization has been interpreted according to the new interfacial model of polymer composites.
Effect of Climatic and Radiation Ageing on Properties of Glass Fibre Reinforced Epoxy Laminates
Authors: Startsev O.V. , Krotov A.S. , Golub P.D.
Published: April 2023

The effect of radiation on the properties of glass fibre reinforced epoxies was investigated. Radiation treatment with a maximum dose of 30 MGy was performed for virgin samples and after 0.5, 1, 2, and 5 years of exposure in cold, moderate and warm damp climates. Evaluation of climatic and radiation resistance was by the change in bending strength, interlaminar shear strength, and Young's modulus. Dynamic mechanical analysis and linear dilatometry were employed to investigate the epoxy matrix during ageing. It has been established that radiation treatment of both virgin and climatically aged samples causes the destruction of the interfacial bond. The large increase in mechanical properties observed is explained by the competing effects of two processes. There is little indication of the occurrence of additional crosslinking of the epoxy binder during irradiation. It is shown that ageing in the reverse order (radiation treatment with subsequent exposure to the climate) is more severe, and intensifies the changes in the properties of the material.
Crystallization and Thermal Properties of Thermoplastic Elastomeric Reactive Blends of Polyamide-6 and Acrylate Rubber
Authors: Jha Abhijit , Bhowmick Anil K.
Published: April 2023

The structural characterization of thermoplastic elastomeric blends of polyamide-6 and acrylate rubber (ACM) has been carried out by wide angle X-ray diffraction analysis (WAXD) and by differential scanning calorimetry (DSC). WAXD results suggest a reduction in the crystallite size as well as an increase in the unit cell dimensions of polyamide-6 crystals in the presence of ACM. DSC results showed a drop in both Tm and the crystallinity of the polyamide-6 phase with the addition of rubber in the blends. The Tg of ACM in the blends was higher than that of pure ACM homopolymer. The elevation of Tg of ACM, coupled with the depression of Tm of polyamide-6, indicates the kinetic restriction of the crystallization process of polyamide-6 in the blends, which is ascribed to the grafting of ACM chains onto the polyamide-6 matrix during the melt blending operation.
Comparative Study of the Fire Behaviour of Glass-Fibre Reinforced Unsaturated Polyesters Using a Cone Calorimeter
Authors: Le Bras Michel , Bourbigot Serge , Mortaigne Bruno , Cordellier Guillaume
Published: April 2023

This work deals with the fire behaviour of unsaturated polyester resin-based composites and with the influence of glass-fibre level on limiting oxygen index and oxygen consumption (in particular the rate of heat release). The combustion products are identified. 65 wt.% reinforcement allows reasonable FR properties using a first generation type resin.
Genome-wide identification and characterization of the chemosensory relative protein genes in Rhus gall aphid Schlechtendalia chinensis
Authors: He Hongli , Crabbe M. James C. , Ren Zhumei
Published: April 2023

Background

TheRhusgall aphidSchlechtendalia chinensisspecially uses the only speciesRhus chinensisand certain moss species (Mniaceae) as its primary host plant and secondary host plants, respectively.Rhusgalls are formed on the primary host by the sucking of aphids, and used in traditional medicine as well as other various areas due to their high tannin contents. Chemoreception is critical for insect behaviors such as host searching, location and identification of mates and reproductive behavior. The process of chemoreception is mediated by a series of protein gene families, including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), olfactory receptors (ORs), gustatory receptors (GRs), ionotropic receptors (IRs), and sensory neuron membrane proteins (SNMPs). However, there have been no reports on the analysis of molecular components related to the chemoreception system ofS. chinensisat the genome level.

Results

We examined the genes of eight OBPs, nine CSPs, 24 ORs, 16 GRs, 22 IRs, and five SNMPs in theS. chinensisgenome using homological searches, and these chemosensory genes appeared mostly on chromosome 1. Phylogenetic and gene number analysis revealed that the gene families, e.g., ORs, GRs, CSPs and SNMPs inS. chinensis, have experienced major contractions by comparing toMyzus persicae,while the two gene families OBPs and IRs had slight expansion. The current results might be related to the broader host range ofM. persicaeversus the specialization ofS. chinensison only a host plant. There were 28 gene pairs between genomes ofS. chinensisandAcyrthosiphon pisumin the chemoreceptor gene families by collinear comparison. Ka/Ks ratios (< 1) indicated that the genes ofS. chinensiswere mainly affected by purification selection during evolution. We also found the lower number and expression level of chemoreception genes inS. chinensisthan in other 11 aphid species, such as ORs, GRs and IRs, which play an important role in host search.

Conclusion

Our study firstly identified the genes of the different chemosensory protein gene families in theS. chinensisgenome, and analyzed their general features and expression profile, demonstrating the importance of chemoreception in the aphid and providing new information for further functional research.
Diagnostic accuracy of left atrial function and strain for differentiating between acute and chronic myocardial infarction
Authors: Jiang Xiaofeng , Yan Yi , Yang Zhi , Wen Miao , Long Yitian , Fu Bing , Jiang Jian
Published: April 2023

Background

The cardiac magnetic resonance tissue tracking (CMR-TT) technique was used to obtain left atrial strain and strain rate in patients with myocardial infarction (MI) and to evaluate the utility of this technique in the quantitative assessment of myocardial infarction for distinguishing acute from chronic myocardial infarction.

Methods

We retrospectively analyzed 36 consecutive patients with acute myocardial infarction (AMI) and 29 patients with chronic myocardial infarction (CMI) who underwent CMR and 30 controls. Left atrial (LA) and ventricular functions were quantified by volumetric, and CMR-TT derived strain analysis from long and short left ventricular view cines. Receiver Operating Characteristics (ROC) analysis was used to determine the diagnostic accuracy of CMR-TT strain parameters for discriminating between acute and chronic myocardial infarction.

Results

AMI and CMI participants had impaired LA reservoir function, conduit function and LA booster pump dysfunction compared to the controls. LA strain was more sensitive than LV global strain for the assessment of the MI stage. Peak late-negative SR yielded the best areas under the ROC curve (AUC) of 0.879, showing differentiation between acute and chronic myocardial infarction of all the LA strain parameters obtained. The highest significant differences between chronic myocardial infarction and normal myocardium were also found in the LV strain (p < 0.001) and LA functional parameters (p < 0.001), but there was no difference between AMI and normals.

Conclusions

CMR-TT-derived LA strain is a potential and robust tool in demonstrating impaired LA mechanics and quantifying LA dynamics, which have high sensitivity and specificity in the differential diagnosis of acute versus chronic myocardial infarction. Their use is thus worth popularizing in clinical application.
Intense pulsed-light treatment improves objective optical quality in patients with meibomian gland dysfunction
Authors: Whang Woong-Joo , Yun Jeongseop , Koh Kyungmin
Published: April 2023

Background

To evaluate changes in objective optical quality following intense pulsed light (IPL) treatment combined with meibomian gland (MG) expression (MGX) in patients with MG dysfunction (MGD).

Methods

This retrospective cross-sectional study included MGD-related dry eye disease (DED) patients who received IPL treatment between March and December 2021 at Kim’s Eye Hospital, Seoul, Republic of Korea. Each patient underwent four sessions of IPL treatment using Lumenis M22 (Lumenis Ltd., Yokneam, Israel) and MGX at three-week intervals.

Results

This study included 90 eyes from 45 patients with MGD. The mean age was 52.3 ± 16.1 years (range, 20–75 years), and 53.3% (24/45) of patients were female. Compared with the baseline, all clinical symptoms and signs significantly improved after IPL treatment combined with MGX. All optical quality parameters obtained with an optical quality analysis system (OQAS: Visiometrics, Castelldefels, Spain) have improved significantly over the baseline (p < 0.001).

Conclusions

In patients with MGD, IPL treatment combined with MGX improved the objective optical quality and clinical signs and symptoms of DED.
Impacting factors and sources of perceived stress by home-quarantined residents in Shanghai during COVID-19 epidemic
Authors: Zhou Yiwei , Chen Zhihui , Li Wancang , Chen Siwei , Xu Haiyun , Zhou Zumu
Published: April 2023

Background

Home-quarantine is one of the most common measures implemented to prevent or minimize the transmission of COVID-19 among communities. This study assessed stress levels of the home-quarantined residents in Shanghai during a massive wave of COVID-19 epidemic this year, explored the stress sources perceived by the respondents, and analyzed the association between each of the sociodemographic factors and the stress level.

Methods

This online survey was launched during April 23 - 30, 2022, the early stage of a massive wave of COVID-19 in Shanghai, China. Participants were quarantined-residents negative for COVID-19. They were asked to list some situations that were their major concerns and perceived stressful, in addition to sociodemographic and COVID-19 related information. Moreover, they were asked to complete the Perceived Stress Scale-14 (PSS-14) for the assessment of stress level.

Results

A total of 488 valid questionnaires were collected from 192 male and 296 female respondents. Overall, 207 persons (42.42%) presented high stress level (PSS-14 score ≥43). The top three concerns perceived stressful by respondents are “not allowed to go outdoors”, “uncertain duration of the epidemic”, and “lack of food supply”. Fewer than 50% of the respondents perceived the other situations stressful. Higher proportions of young adults (≤ 29 years old), males, unemployed, singles, and those with low income (≤ 1999 yuan/month) perceived high stress compared to their counterparts, none of COVID-19 related factors is associated with the stress level, including location of residence, result of nucleic acid test, knowledge about COVID-19, whether vaccinated, and quarantine duration.

Conclusion

Home-quarantine applied to people negative for COVID-19 led to a lot of major concerns that may be perceived stressful, whereas the virus-related factors did not show significant impact on mental health of the respondents.
A scoping review on the decision-making dynamics for accepting or refusing the COVID-19 vaccination among adolescent and youth populations
Authors: Blahut Roger , Flint Amanda , Orlando Elaina , DesChatelets Joelle , Khowaja Asif
Published: April 2023

Background

Global COVID-19 vaccinations rates among youth and adolescent populations prove that there is an opportunity to influence the acceptance for those who are unvaccinated and who are hesitant to receive additional doses. This study aimed to discover the acceptance and hesitancy reasons for choosing or refusing to be vaccinated against COVID-19.

Methods

A scoping review was conducted, and articles from three online databases, PubMed, Wiley, and Cochrane Library, were extracted and screened based on exclusion and PICOs criteria. A total of 21 studies were included in this review. Data highlighting study attributes, characteristics, and decision-making dynamics were extracted from the 21 studies and put into table format.

Results

The results showed that the primary drivers for accepting the COVID-19 vaccine include protecting oneself and close family/friends, fear of infection, professional recommendations, and employer obligations. Primary hesitancy factors include concerns about safety and side effects, effectiveness and efficacy, lack of trust in pharmaceuticals and government, conspiracies, and perceiving natural immunity as an alternative.

Conclusions

This scoping review recommends that further research should be conducted with adolescent and youth populations that focus on identifying health behaviors and how they relate to vaccine policies and programs.
K-means clustering of outpatient prescription claims for health insureds in Iran
Authors: Momahhed Shekoofeh Sadat , Emamgholipour Sefiddashti Sara , Minaei Behrouz , Shahali Zahra
Published: April 2023

Objective

The segmentation of consumers based on their behavior and needs is the most crucial action of the health insurance organization. This study's objective is to cluster Iranian health insureds according to their demographics and data on outpatient prescriptions.

Setting

The population in this study corresponded to the research sample. The Health Insurance Organization's outpatient claims were registered consecutively in 2016, 2017, 2018, and 2019 were clustered.

Design

The k-means clustering algorithm was used to cross-sectionally and retrospectively analyze secondary data from outpatient prescription claims for secondary care using Python 3.10.

Participants

The current analysis transformed 21 776 350 outpatient prescription claims from health insured into 193 552 insureds.

Results

Insureds using IQR were split into three classes: low, middle, and high risk. Based on the silhouette coefficient, the insureds of all classes were divided into three clusters. In all data for a period of four years, the first through third clusters, there were 21 799, 7170, and 19 419 insureds in the low-risk class. Middle-risk class had 48 348,23 321, 25 107 insureds, and 14 037, 28 504, 5847 insured in the high-risk class were included. For the first cluster of low-risk insureds: the total average cost of prescriptions paid by the insurance for the insureds was $211, the average age was 26 years, the average franchise was 88.5US$, the average number of medications and prescriptions were 409 and 62, the total average costs of prescriptions Outpatient was 302.5 US$, the total average number of medications for acute and chronic disease was 178 and 215, respectively. The majority of insureds were men, and those who were part of the householder's family.

Conclusions

By segmenting insurance customers, insurers can set insurance premium rates, controlling the risk of loss, which improves their capacity to compete in the insurance market.
In-bag abdominal manual morcellation versus contained power morcellation in laparoscopic myomectomy: a comparison of surgical outcomes and costs
Authors: Güven Cenk Mustafa , Uysal Dilek
Published: April 2023

Background

To compare the surgical outcomes and costs of in-bag abdominal manual morcellation (AMM) and contained power morcellation (PM) in laparoscopic myomectomy.

Methods

A total of 61 patients were divided into two groups based on their myomectomy specimen extraction methods: AMM group (n = 33) and electromechanical contained PM group (n = 28). The surgical outcomes and cost were compared between groups. During AMM, a glove bag (in 27 patients) and an endo bag were used (in 6 patients) according to the myoma size.

Results

Morcellation time (18 ± 9.2 min vs. 37.4 ± 14.1 min) and total operation time (100 ± 24.3 min vs. 127 ± 33.1 min) were significantly lower in the AMM group compared to those in the PM group. Other surgical outcomes, which were similar between groups, included delta hemoglobin, length of hospital stay and VAS score at 12 and 24 h postoperatively. There were no per- or postoperative complications in both group with no conversion to laparotomy. One patient was transfused with two units of erythrocyte suspension postoperatively in the PM group. Sarcoma was not diagnosed in any of the cases in both group.

Conclusion

The in-bag AMM or contained PM for specimen extraction resulted in similar outcomes in terms of delta hemoglobin, postoperative pain intensity (VAS score at 12 and 24 h postoperatively), the need for additional analgesia, and the length of hospital stay; however, total operation time and morcellation time were significantly shorter in the AMM group, indicating a prominent advantage. Significant cost-effectiveness is also a critical advantage of in-bag AMM compared to containing PM.
Endometriosis in an ectopic kidney: a rare case report and literature review
Authors: Chen MengLin , Yu YuanMeng , Zhao XinXiang
Published: April 2023

Background

Endometriosis mainly occurs in female pelvic organs. Endometriosis in the kidney is extremely rare.

Case presentation

We herein describe a case of a 19-year-old girl with occasional mild abdominal pain associated with an ectopic left kidney. SPECT-CT showed no abnormal radioactive distribution in the left pelvis, suggesting loss of function of the ectopic kidney. Laparoscopic left ectopic kidney resection was subsequently performed. Histopathology revealed endometriosis of the ectopic left kidney.

Conclusions

In female patients with clinical manifestations of abdominal pain and gross hematuria, the possibility of renal endometriosis should be considered.