Solution-processed white graphene-reinforced ferroelectric polymer nanocomposites with improved thermal conductivity and dielectric properties for electronic encapsulation

The recent surge in graphene research has stimulated interest in the investigation of various two-dimensional (2D) nanomaterials, including 2D boron nitride (BN) nanostructures. Among these, hexagonal boron nitride nanosheets (h-BNNs; also known as white graphene, as their structure is similar to that of graphene) have emerged as potential nanofillers for preparing thermally conductive composites. In this work, hexagonal boron nitride nanoparticles (h-BNNPs) approximately 70 nm in size were incorporated into a polyvinylidene fluoride (PVDF) matrix with different loadings (0–25 wt.%). The PVDF/h-BNNP nanocomposites were prepared by a solution blending technique and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), polarized optical microscopy (POM) and scanning electron microscopy (SEM). In addition, the thermal conductivity and dielectric properties of the nanocomposites were investigated. The incorporation of h-BNNPs in the PVDF matrix resulted in enhanced thermal conductivity. The highest value, obtained at 25 wt.% h-BNNP loading, was 2.33 W/mK, which was five times that of the neat PVDF (0.41 W/mK). The thermal enhancement factor (TEF) at 5 wt.% h-BNNP loading was 78%, increasing to 468% at 25 wt.% h-BNNP loading. The maximum dielectric constant of approximately 36.37 (50Hz, 150 °C) was obtained at 25 wt.% h-BNNP loading, which was three times that of neat PVDF (11.94) at the same frequency and temperature. The aforementioned results suggest that these multifunctional and high-performance nanocomposites hold great promise for application in electronic encapsulation.     

Clearance of the SARS-CoV-2 Virus in an Immunocompromised Patient Mediated by Convalescent Plasma without B-Cell Recovery

Coronavirus disease (COVID-19) is a contagious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This case report presents a patient who had difficulty eradicating the corona virus due to being treated with Rituximab, which depletes B lymphocyte cells and therefore disables the production of neutralizing antibodies. The combined use of external anti-viral agents like convalescent plasma, IVIG and Remdesivir successfully helped the patient’s immune system to eradicate the virus without B-cell population recovery. In vitro studies showed that convalescent plasma is the main agent that helped in eradicating the virus.     

Biological treatment of azo dyes on effluent by Neurospora sp isolated and adopted from dye contaminated site

Abstract

Application of fungal agents to develop eco-friendly and cost-effective dye removal from textile effluent was studied. A fungal strain Neurospora sp has been isolated from effluent site and tested for its ability to biosorption and biodegrade azodyes. Biosorption of azo dyes by live and dead fungal biomass was evaluated. Percentage of decolorization was found to be effective against all tested azodyes and ranges between 33 and 76%. Nearly 72% of azo dyes were removed by dead Neurospora sp biomass and 86% respectively by live active biomass. Biodegradation of textile effluent by Neurospora sp showed changes in BOD, COD and TOC indicates that isolated Neurospora sp effectively degrade and utilize the dye as a sole carbon source. The initial TOC of 2600?mg/L was approximately reduced to almost its three fourth within a week. Research works on application of fungal biomass on textile effluent treatment have proven decolorizing potential among a wide range of anionic and cationic dyes. Based on the results, the biosorption mechanism by Neurospora sp was observed as effective, economic and eco-friendly decontaminant.     

Monitoring of Corrosion in Structural Reinforcing Bars: Performance Comparison Using In Situ Fiber-Optic and Electric Wire Strain Gauge Systems

This work addresses the problems of effective in situ measurement of the initiation or the rate of steel corrosion in reinforced concrete structures through the use of optical fiber sensor systems. By undertaking a series of tests over prolonged periods, coupled with acceleration of corrosion, the performance of fiber Bragg grating-based sensor systems attached to high-tensile steel reinforcement bars (ldquorebarsrdquo), and cast into concrete blocks was determined, and the results compared with those from conventional strain gauges where appropriate. The results show the benefits in the use of optical fiber networks under these circumstances and their ability to deliver data when conventional sensors failed.     

E-Shaped Patch Antennas for Multitasks/Uninterrupted 5G Communications

Wireless Personal Communications - The future communication system is a fifth generation (5G) wireless communication. This communication system requires an antenna with a simple design, low traffic...     

Protection provided by surface treatments against chloride induced corrosion

Corrosion of reinforcement bars due to chloride ingress is a well known problem in reinforced concrete. Several methods have been adopted to protect reinforced concretc, and one of them is to provide added protection to the concrete surface in the form of surface treatments such as silanes and siloxanes. They react with the cement matrix and form a hydrophobic layer on the walls of the pores within the concrete. This protects the concrete from the ingress of water and water-born salts. Moisture is required for reaction of silanes and siloxanes with the hydrated cement matrix. However, too much water in the pores of concrete will prevent the treatments from penetrating deeper into the pores. A study has been carried out to investigate the variation, due to the presence of moisture, on the effectiveness of the protection. It has been found that irrespective of the moisture content at the time of application of treatment, silanes and siloxanes provided good protection against chloride ingress and corrosion of reinforcement bars. However, the depth of penetration and therefore the durability of the treatment is adversely affected when the concrete is near saturation.

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Résumé Dans le béton armé, la corrosion des armatures de renforcement due à la pénétration du chlorure est un problème bien connu. Plusieurs méthodes ont été adoptées pour protéger le béton armé, dont la protection supplémentaire au revêtement du béton sous forme de traitement à la surface par des silanes et des siloxanes. Ces produits réagissent avec la matrice cimentaire et forment une couche hydrophobe sur les parois des pores à l'intérieur du béton, empêchant la pénétration de l'eau et des sels véhiculés par l'eau. L'humidité est nécessaire pour obtenir la réaction des silanes et des siloxanes avec la matrice cimentaire hydratée. Cependant, trop d'eau dans les pores du béton empêche les traitements de pénétrer plus profondément dans les pores. Une étude a été menée sur l'efficacité de la protection en fonction des variations de la présence de l'humidité. On a constaté que, quelle que soit la teneur en humidité au moment de l'application du traitement, les silanes et les siloxanes fournissent une bonne protection contre l'entrée du chlorure et la corrosion des armatures. Néanmoins, la profondeur de la pénétration, et donc la résistance du traitement, sont défavorablement modifiées lorsque le béton est près de la saturation.

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Editorial note Prof. David J. Cleland is a RILEM Senior Member and the Secretary of TC 145-WSM (Workability of Special Concrete Mixes). Prof. A. E. Long is a RILEM Senior Member and a member of TCs 126-IPT (In-place Testing of Hardened Concrete) and 163-TPZ (Interfacial Transition Zone and Properties of Transfer).     

Testing the effectiveness of commonly-used site curing regimes

A range of seven test methods was used to asses the effectiveness of curing on C30 and C50 Portland cement concretes. Curing was by formwork retention, wrapping in wet hessian or wrapping in polythene for periods of between one and seven days. Specimens from each mix were also subjected to both air and water storage. Electrical resistance measurement and water absorption by immersion were ineffective in distinguishing the effects of different curing regimes. Air permeability, water sorptivity, surface pull-off strength, mercury intrusion porosimetry and accelerated carbonation were able to show distinct differences between air storage and immersion in water. These tests were generally ineffective in distinguishing trends for practical curing techniques.

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Résumé Sept méthodes d’essai ont été employées pour évaleur leur efficacité dans la cure, des bétons de ciment Portland C30 et C50. Les cures ont été effectuées au moyen de coffrages de rétention, ou par enveloppement en toile de chanvre mouillé ou en polythène, pour des périodes allant de un à sept jours. Des échantillons de chaque mélange ont également été soumis à l’air et conservés dans l’eau. Les mesures de résistance électrique et d’absorption de l’eau par immersion n’ont pas été efficaces pour différencier les effets des différents méthodes de cure. Par contre, les mesures de perméabilité de l’air, de sorptivité de l’eau, de résistance à tirage superficielle, de porosimétrie de pénétration de mercure et de carbonatation accélérée ont permis de montrer des différences marquées entre la conservation à l’air et à l’eau. En général, ces essais ne se sont pas montrés efficaces pour déterminer des tendances applicables aux techniques de cure dans la pratique.

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Editorial note Dr. B.K. Marsh and M.A. Ali work at the Building Research Establishment, U.K., which is a RILEM Titula Member.     

Interesterification kinetics of triglycerides and fatty acids with modified lipase inn-hexane

The kinetics of lipase-catalyzed interesterification of triglycerides and fatty acids in organic media was studied. First, the lipase Saiken 100,Rhizopus japonicus, was modified by surfactant to form an enzyme precipitate in aqueous solution, which was well dispersed in organic solvents. This modified lipase catalyzed the interesterification of tripalmitin and stearic acid. The enzyme has 1,3-positional specificity and does not distinguish between stearic and palmitic acids. The kinetic model developed to describe the interesterification reaction system is based on mass balance of two consecutive second-order reversible reactions. The reaction rate constant, k, was determined by solving the differential rate equations of the reaction system and by expressing the value of k as a function of concentrations of the substrates with time. The model gave satisfactory results. The best value of the specific reaction rate constant k* that fits all experimental data was 1.2 · 10⁻⁵ [L²/(mmol · mg biocatalyst · h)] under the reaction conditions in this study.     

Evaluation of mixed‐model U‐line operational designs

Often in lean manufacturing, multiple products are produced in U‐shaped manufacturing cells to simultaneously achieve product variety and production efficiency. We examine two design issues for mixed‐model U‐lines: work rules (a first‐come‐first‐serve rule and a crossover‐and‐return rule) and inventory flow choices (direct flow and buffered flow). Simulation results indicated that throughput and labor utilization can be improved by implementing a “buffer” with the first‐come‐first‐serve rule. Interestingly, the effectiveness of an inventory flow choice was dependent on the work rule (interaction effect), and relationships among performance dimensions differed across the designs.