Advancements in technology and widespread usage of electronic equipment have led to a vast hike in electromagnetic pollution such as electromagnetic interference (EMI). This has resulted in major concerns regarding human health and improper functioning of electronic devices. Therefore, high-performance EMI shielding materials are necessary to ensure human well-being and protect systems in domestic, civil, or military applications. Earlier, metals and alloys of metals served as EMI shielding materials. But due to their heavy weight, low corrosion resistance, and advancements in miniaturization of electronic devices, currently, metals have only restricted applications in EMI shielding. Thus, flexible, lightweight, and high-performance EMI shielding materials assume great significance. Polymer composites have emerged as a better alternative to EMI shielding materials because of their light weight, corrosion resistance, and ease of fabrication. This article reviews the important literature on electrospun polymer composite fibers for EMI shielding applications. Fabrication methods and different types of fillers and their influence on EMI shielding properties are discussed in detail. The article tries to highlight the huge potential of the electrospinning technique toward the development of specialty materials for EMI shielding.
Electrospinning is a useful and convenient method for producing ultrathin fibers. It has grabbed the scientific community’s interest due to its potential to produce fibers with various morphologies. Numerous efforts have been made by researchers and industrialists to improve the electrospinning setup and the associated techniques in order to regulate the morphology of the electrospun fibers for practical applications. Porous, hollow, helical, aligned, multilayer, core-shell, and multichannel fibers have been fabricated for different applications. This chapter aims to provide readers with a clear understanding of the electrospinning process: its principle, methodology, materials, and applications. The chapter begins with a brief introduction to the history of electrospinning, followed by a discussion of its principle and the basic components of electrospinning setup. The parameters that affect the electrospinning process such as operating parameters and the properties of the material being electrospun are discussed briefly. An overview of the different types of electrospinning technique, capable of producing nanofibers with different morphologies, is also presented. Afterward, the applications of electrospun nanofibers, including their use in biomedical applications, filtration, energy sectors, and sensors applications are discussed succinctly. The perspectives on the challenges, opportunities, and new directions for future development of electrospinning technology are also offered.
High-performance green electromagnetic interference (EMI) shielding materials are in great demand due to the growing need for portable electronic devices and high speed digital communication devices. Developing high-efficiency, lightweight, and flexible EMI shielding materials for practical applications is still a major challenge. Herein, we demonstrate a facile approach for fabricating thin and lightweight N-doped carbon nanofibers (CNFs) containing La 0.85 Sr 0.15 CoO 3−δ (LSCO) nanoparticles (NPs) (LSCO-CNFs) through electrospinning followed by heat treatment. CNFs incorporated with 25 wt % LSCO NPs (LSCO-CNFs-25) exhibited high electrical conductivity (2.1 S cm −1 ) and high EMI shielding effectiveness (EMI SE) of 45 dB with a low thickness (0.08 mm) in Xband, K u -band, and K-band (8.2−26.5 GHz). The material showed an absorption-dominated shielding mechanism due to formation of a 3D electrically conductive network, high interfacial polarization arising from the presence of LSCO NPs in CNFs, and the porous and layer-by-layer structure of CNFs. The flexible polydimethylsiloxane (PDMS) composites of LSCO-CNFs were prepared by hand lay-up methods for enhancing the mechanical properties and hydrophobicity. The LSCO-CNFs-25 PDMS composites exhibited a high EMI SE of 45.6 dB with a thickness of 0.62 mm. The LSCO-CNFs-PDMS composites are ideal for fabricating lightweight, thin, waterproof, flexible, and high-performance EMI shielding materials.
A simple method of production of carbon foams by randomly assembling short vermicelli rods and bonding them using phenol-formaldehyde (PF) followed by foaming in the solid state during carbonization has been reported. The brittle vermicelli becomes ductile in the range of 200−250 °C during carbonization, which facilitates the nucleation and growth of bubbles in the solid state due to the water vapor generated by the -OH condensation of starch. The dense PF coating on the vermicelli surface facilitates the enlargement of cells by restricting the escape of water vapor during the solid state foaming. The dense carbon produced from the PF binds the carbonized vermicelli rods, affording structural integrity and mechanical strength. The foam body consists of open intervermicelli void space and closed cellular pores in the carbonized vermicelli rods. A broad cell size range of 4−142 μm with an average value of 29.2 μm is observed. The density, compressive strength, and thermal conductivity of the carbon foam are modulated in the ranges of 0.30−0.34 g cm −3 , 0.63−1.6 MPa, and 0.162−0.222 W m −1 K −1 , respectively, by changing the PF solution concentration in the range of 50−90 vol %. The carbon foams exhibit absorption-dominated electromagnetic interference shielding with total shielding effectiveness and specific shielding effectiveness in the ranges of 47.5−65.6 dB and 155.2−192.9 dB cm 3 g −1 , respectively, for the X band (8.2−12.4 GHz).
Background: Dengue is an acute viral infection has emerged as a notable public health problem. Rapid immunochromatographic test and IgM/IgG ELISA has been the mainstay of diagnosis. Combination of NS1 antigen detection along with antibody detection increases the diagnostic rates. Thrombocytopenia begins during febrile phase. Therefore, we tried to evaluate the association of platelet counts against immunochromatographic test (NS1 and IgM/IgG) and IgM ELISA in dengue infections.
Methodology: The study of variation in different platelet parameters in dengue fever cases was undertaken in our department over a period of 18 months from July 2017 to December 2018. Inclusion criteria: All patients with clinical features and serologically positive dengue infection included.
Exclusion criteria: Patient’s which are serologically negative dengue and if routine laboratory test suggesting a bacterial, parasite or any viral infection other than dengue infection or any other disease.
CBC was done from all clinically suspected dengue cases. Serum samples were tested for NS1, IgM and IgG by immunochromatography-based test and IgM MAC-Capture ELISA. Platelet counts were obtained from all serologically positive cases. Test results of dengue specific parameters were compared against platelet counts.
Results: Of 636 samples tested, 396 were positive for one or more dengue parameters. Of the 396, 312 were positive for NS1, 152 were positive for IgM, 41 were positive for IgG and 354 were positive for IgM ELISA. Thrombocytopenia was consistently associated with one of the serological parameters.
Conclusion: It can be concluded from our study that Thrombocytopenia was found in all serological positive dengue cases and showed a significant correlation with serological markers.
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