Search

Flexible free standing electrospun poly (vinylidene fluoride)/ZnFe 2 O 4 composite fiber mats were synthesized through electrospinning technique. Structural and morphological studies of PVDF/ZnFe 2 O 4 composite fibers were examined by X-ray diffraction and scanning electron microscopy. The functional groups and the percentage of β phase were analysed using FTIR studies. 92% beta phase was achieved with the incorporation of ZnFe 2 O 4 filler. The enhancement in dielectric and ferroelectric properties of the composite fiber mats were observed with a maximum dielectric constant and polarization values of 15 and 0.72 μC/cm2 respectively for 20 wt% filler loading. The domain switching behaviour of the mats were analysed using DC-EFM. Vibration sample magnetometry results revealed the antiferromagnetic nature of the composite fiber mats with a maximum magnetization of 0.18 emu/cm3. Further, the energy storage density of the mats was studied and a maximum energy storage density of 239 mJ/cm3 was obtained which was 1.4 times than that of pure PVDF mat. [ABSTRACT FROM AUTHOR]

• CoFe 2 O 4 fibers were synthesised by using electrospinning technique. • Continuous fiber nature of CoFe 2 O 4 proved by SEM, TEM and AFM characterization. • Improved magnetic properties of CoFe 2 O 4 confirmed by VSM studies. • Room temperature gas sensor performances of CoFe 2 O 4 under different test gases were tested. In this study, ferromagnetic cobalt ferrite (CoFe 2 O 4) fibers were synthesized by electrospinning technique using a DMF/ethanol mixed precursor solution of poly (vinyl pyrrolidone) (PVP) and cobalt and iron (III) nitrates. The as-spun precursor fibers were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses and calcined at 500, 600 and 800 °C with a heating rate of 2 °C/min to obtain CoFe 2 O 4 fibers. Morphological studies confirmed the formation of a continuous bead-free fiber structure in the calcined samples with an average fiber diameter and particle size of 208 nm and 48 nm respectively. Magnetic hysteresis loops of CoFe 2 O 4 fibers revealed their ferromagnetic nature, with a maximum saturation magnetization of 76.5 emu/g and a coercivity of 948 Oe. At room temperature, the variation of resistance and the corresponding response toward various test gases of different concentrations were systematically investigated. The sensing response of CoFe 2 O 4 fibers toward ammonia was found to be better than toward other test gases such as ethanol, methanol, acetone, and 2-propanol. CoFe 2 O 4 fibers showed good reproducibility and a maximum response of 0.42 at 900 ppm concentration of ammonia. They also exhibited the ability to sense a very low concentration of ammonia (even at 25 ppm) at room temperature. [ABSTRACT FROM AUTHOR]

In this paper, the importance of mass and heat transfer characteristics of mixed convective conditions on nonlinear free convection flow embedded with non-Fourier flux and thermal radiation is numerically investigated. A partial Casson slip and mixed impact of thermophoresis and Brownian motion is considered at the elastic surface. To change the highly nonlinear partial differential equations into ordinary differential system, we used the similarity transformations and then the shooting method is employed to solve resulting equations. The significance of various physical parameters on the velocity, concentration and temperature profiles are investigated for both negative value of ferromagnetic interaction ( β 1 = − 0. 2) and positive value of ferromagnetic interaction ( β 1 = 0. 2). The governing physical aspects of coefficient of skin friction, the Sherwood and Nusselt numbers are obtained for various embedded parameters. Our findings concluded that the ferromagnetic interaction is positive and then more mass transfer rate is identified compared to the negative value of ferromagnetic interaction, but whereas in friction and heat transfer rate, it was completely mixed sense (i.e., different effects have different results). Brownian motion has less Nusselt number values in positive ferromagnetism compared to negative ferromagnetism and quite opposite behavior is observed in the presence of thermophoresis, this happened due to nonlinear flux and buoyancy. [ABSTRACT FROM AUTHOR]

A theoretical analysis is performed for investigating the flow and heat transfer characteristics of Maxwell fluid over a stretching cylinder with Cattaneo-Christov, heat source or sink, and suction/injection. The solution to the transformed similarity equations is derived using Runge-Kutta fourth-order method along shooting technique. The present result for both the surface shear stress and the local Nusselt number is validated with the previously published results, while a very sound agreement is attained. The impacts of the distinct parameters related to this study are presented in graph and tabular form, respectively. Moreover, the local Nusselt number and surface shear stress have been computed for both the suction and injection cases. It is found that strengthening the thermal relaxation parameter value increases the heat transfer rate. The dimensional heat transfer rate is observed being rising in the injection case when compared with the suction case. [ABSTRACT FROM AUTHOR]

The article presents a study on delineation of buried channels of Bharathappuzha river in Kerala, India by single-channel shallow seismic survey. The findings include seismogram of profiles showing that flanks of the channel were inclined which truncate the underlying strata, the main channel which extended from the present river mouth to the deep sea being clearly identified, and two sets of channels found in the northern and the southern parts of the study area.