Challenges and Developments in Secure Routing Protocols for Healthcare in WBAN: A Comparative Analysis

Wireless Personal Communications - The rise in life expectancy of humans, COVID-19 pandemic and growing cost of medical services has brought up huge challenges for the government and healthcare...     

Thermal degradation and flammability of nanocomposites composed of silica cross-linked to poly(methyl methacrylate)

The effect of polymer cross-linkages on thermal degradation of silica/poly (methyl methacrylate) (PMMA) nanocomposites is investigated using a single novel nanoparticle. Nanosilica surface treated with KH570, an organic surface treatment capable of free-radical polymerisation, was used to cross-link PMMA via an in situ method. Scanning electron microscopy was used to characterise nanosilica before use, while X-ray diffraction confirmed silica was well dispersed in PMMA. Thermogravimetric analysis (TGA) results showed that thermal degradation of silica cross-linked nanocomposites was significantly stabilised compared to PMMA, with a 30% reduction in the peak mass loss rate. Kinetic studies revealed the degradation of nanocomposites in this work abide by first-order kinetics, with an increase in the degradation activation energy of approximately 100?kJ?mol^?1. This is nearly double the improvement compared to conventional PMMA-silica nanocomposites in literature, showing dramatic enhancements to thermal stability. Analysis of high-temperature residuals from TGA tests suggest that cross-linked silica have increased char yields when compared with both PMMA and traditional silica nanocomposites. Cone Calorimetry results showed the materials in this work have reduced heat release rates compared to PMMA and traditional silica-PMMA nanocomposites.     

Tungsten Oxide Thin Film Characterizations for Acetone Gas Detection

The gas sensing properties and topology of tungsten oxide thin films deposited by reactive-ion radio frequency magnetron sputtering at room temperature have been investigated. The abnormalities in behaviour of sensing film are observed when acetone gas is flowed over surface. The reduction reaction of surface and oxidation reaction of acetone gas have been studied. As the gas comes in contact with the surface, the molecules tend to reduce the surface, hence decreasing the resistance. The sensing film was annealed to 500 °C for 1 h for the purpose of achieving a suitable grain size for sensing to take place. Operational optimum temperature for sensing has been computed to be 260 °C. A grain size of 7.3 nm has been computed through analysis of AFM image and a film thickness of 100 nm has been calculated through surface profiler. The SEM image of the film demonstrates the grains developed on the surface. The XRD patterns reveal that the oxide showed up as WO₂. It has been observed that the response percentage is approximately 30% for acetone vapour concentration of 20 ppm and approximately 18% for the concentration of 15 ppm. The response time of the sensor is approximately 5 min and the recovery time is 4 min.     

Protein adsorption characteristics of plasma treated polyurethane surfaces

The effect of various plasma surface treatments on the protein adsorption characteristics of two polyurethane elastomers (Acushnet E417-0 [ACx] and Texin 480 AR [TN]) were studied. Both substrates are based upon diphenylmethane 4,4-diisocyanate (MDI) hard segments and polyester soft segments. Adsorption characteristics of the untreated samples were initially established, followed by plasma treated surfaces. Contact angle and 2 h albumin adsorption were determined. (1) Results of this study indicate that the protein adsorption characteristics of crosslinked substrate ACx is more linear than that of non-crosslinked substrate TN. Further, substrate TN adsorbs seven-fold greater protein at a rate four times higher on its surface than ACx.N,N-Ethylene bis (stearamide), a processing aid used in substrate TN, may encourage greater protein adsorption on substrate TN and variation in the soft segment mobility between the substrates also may affect their adsorption characteristics. (2) Plasma treatments using CH₄ and/or C _x F _y chemistries increased the contact angle for both substrates while those with O₂ and O₂/CF₄ decreased the contact angle for the substrates considered. In general, the contact angle of the substrates exhibiting greater protein adsorption was smaller.     

A finite element solution for the two-dimensional elastic contact problems with friction

A numerical procedure developed for solving the two-dimensional elastic contact problems with friction is presented. This is a generalization of a procedure developed by Francavilla and Zienkiewicz to include frictional effects under proportionate loading. The method uses the flexibility matrix obtained by inversion of condensed stiffness matrix formed by eliminating all the nodes except those where contact is likely to take place and those with external forces. Compatibility of displacements for both normal and tangential directions is applied to those nodes which do not slip. However, for the nodes which slip, compatibility of displacements is applied for normal direction only and slip condition is applied in the tangential direction. The technique has been applied to several problems and very good results have been obtained. The number of iterations needed are very small.     

Study of molecular structure and vibrational spectra of poly (β,-l-malic acid) [PMLA] using DFT approach

Poly (β-L-malic acid) (PMLA) is a biodegradable polymer and it has various important applications in the biomedical field. In the present work the structural and spectral characteristics of PMLA have been studied by methods of infrared, Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) using oligomeric approach employing B3LYP with complete relaxation in the potential energy surface using 6-311++G (d, p) basis set. Based on results, we have discussed the correlation between the vibrational modes and the structure of the PMLA. A complete analysis of the experimental infrared and Raman spectra has been reported on the basis of wavenumber of the vibrational bands and potential energy distribution. The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The calculated infrared and the Raman spectra of the polymer based on DFT calculations show reasonable agreement with the experimental results.     

Biomineralized and chemically synthesized magnetic nanoparticles: A contrast

Magnetic nanoparticles (MNPs) have widely been synthesized through chemical processes for biomedical applications over the past few decades. Recently, a new class of MNPs, known as bacterial magnetosomes, has been isolated from magnetotactic bacteria, a natural source. These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it. Contrary to MNPs, bacterial magnetosomes are biocompatible, lower in toxicity, and can be easily cleared from the body due to the presence of a phospholipid bilayer around them. They also do not demonstrate aggregation, which makes them highly advantageous. In this review, we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis, properties, and biomedical applications. In addition, we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications.     

Out-of-plane flexibilities of dovetail joints in machine tool structures

The paper aims to model the flexibility of a dovetail joint encountered in machine-tool structures. The investigation is concerned with the determination of a flexibility matrix through an approximate semianalytical procedure using finite element analysis. The contact region and the pressure distribution on the two mating surfaces are assumed. The deformation pattern of the male and female parts are separately analysed and from compatibility and equilibrium considerations, the overall deformation pattern of the joint is calculated for the three out of plane external force/moment components. The joint flexibility is represented by a 3 × 3 flexibility matrix. Results are presented for the knee-column joint and the column-overarm joint of a milling machine structure.     

Amebic peritonitis

A total of 18 patients with amebic peritonitis were studied. Fourteen of these cases were due to rupture of amebic liver abscess into the peritoneum and the remaining cases were due to perforation of amebic colitis. No initial suspicion of amebic etiology was made in more than half of the cases. In the group of ruptured liver abscesses, nearly half of the patients showed right lower lung syndrome. The diagnosis in 13 of 14 cases of rupture of liver abscess was confirmed on aspiration. Patients with ruptured amebic liver abcess were of two types: 1. Diffuse type with diffuse signs, shorter duration of illness and poor prognosis. 2. Localized type with longer duration of illness, marked signs of peritonitis and better prognosis. Once the diagnosis of peritonitis was made, the management was surgical. Conservative treatment was tried only in cases with signs of localization. The mortality rate had been 33% in amebic liver abscess rupturing into the peritoneum and 75% in perforation of the intestine. A high index of suspicion of amebiasis in patients with an acute abdomen and institution of early treatment are recommended to help in reducing this mortality. Amebic liver abscess and amebic dysentery should be treated energetically to avoid this fatal complication and surgical intervention whenever indicated should not be delayed.