[en] Nanocomposites of single-phase iron oxide (α-Fe₂O₃) and reduced graphene oxide (rGO) with different volume fractions have been prepared by chemical route. Structural, morphological and spectroscopic characterizations have been performed by XRD, FESEM, TEM, XPS and Raman studies. Photocatalytic activity of these composites has been investigated by the degradation of methylene blue dye under visible light irradiation. The activity is found to depend on the percentage of volume fraction (v_f) of rGO in the composite. At $v_{\text{f}}=10.3,$ the photocatalytic activity becomes maximum and the degree of degradation of MB is found to be ~ eight times to that of pure α-Fe₂O₃. The enhanced photocatalytic activity may be attributed to the prolonged lifetime of electron–hole pair produced in α-Fe₂O₃. The stability and reusability of photocatalyst during photocatalytic reaction, which is a crucial factor for the practical applications, is also verified. At this particular volume fraction of rGO, i.e., v_f = 10.3, the nanocomposite exhibits huge dielectric constant ~ 2950 times to that of pure α-Fe₂O₃ along with moderate dielectric loss enabling it a potential candidate for charge storage device.

[en] Nanocomposites of single-phase iron oxide (α-Fe₂O₃) and reduced graphene oxide (rGO) with different volume fractions have been prepared by chemical route. Structural, morphological and spectroscopic characterizations have been performed by XRD, FESEM, TEM, XPS and Raman studies. Photocatalytic activity of these composites has been investigated by the degradation of methylene blue dye under visible light irradiation. The activity is found to depend on the percentage of volume fraction (υ_f) of rGO in the composite. At υf=10.3, the photocatalytic activity becomes maximum and the degree of degradation of MB is found to be ~ eight times to that of pure α-Fe₂O₃. The enhanced photocatalytic activity may be attributed to the prolonged lifetime of electron–hole pair produced in α-Fe₂O₃. The stability and reusability of photocatalyst during photocatalytic reaction, which is a crucial factor for the practical applications, is also verified. At this particular volume fraction of rGO, i.e., υf = 10.3, the nanocomposite exhibits huge dielectric constant ~ 2950 times to that of pure α-Fe₂O₃ along with moderate dielectric loss enabling it a potential candidate for charge storage device. (author)

[en] The effects of dust charge variations on low-frequency wave modulations in an electronegative dusty plasma are investigated. The dynamics of the modulated wave is governed by a nonlinear Schroedinger equation with a dissipative term. The dissipation arises due to the nonsteady (nonadiabatic) dust charge variations. Theoretical and numerical investigations predict the formation of dissipative bright (envelope) and dark solitons. The nonsteady charge-variation-induced dissipation reduces the modulational instability growth rate and introduces a characteristic time scale to observe bright solitons. Results are discussed in the context of electronegative dusty plasma experiments.

[en] The effects of both adiabatic and nonadiabatic charge variations on small but finite amplitude nonlinear dust acoustic wave (DAW) have been investigated in an electronegative dusty plasma in presence of a static magnetic field. It is found that in case of adiabatic charge variations, the nonlinear wave is governed by the Zakharov-Kuznetsov (ZK) equation which yields the usual solitary wave solution. On the other hand, in case of nonadiabatic charge variations, the dynamics is governed by the Zakharov-Kuznetsov-Burgers' (ZKB) equation which exhibits shock like structures. The results are discussed in the context of cometary plasma.

[en] The rare earth elements (like lanthanum) and other metals like zirconium, arsenic, potassium, copper etc. are some of the elements, which are found in the natural surrounding. Since these metals have immense utility in the field of medical science, energy efficient electronic devices, nuclear energy domain, early and easy detection of such metals is very important. In the present work, voltammetric electronic tongue for detection and quantitative determination of these elements has been explored. A sensor array comprising of noble metals (like gold, iridium, rhodium etc) has been developed and it exhibits remarkable sensitivity and promising results for detection and analysis of these elements.

[en] The development of a new kind of self-powered vibration sensor (SPVS) with cantilever structure made with polymeric piezoelectric material for low frequency vibrations detection is demonstrated. Methylammonium lead bromide (MAPB) particles incorporated poly(vinylidene fluoride) (PVDF) composite film exhibiting significant yield of piezoelectric β-phase and outstanding flexibility that resulting superior mechanical energy harvesting behaviour. The composite films also possess relatively increased dielectric constant than PVDF film. The resonance frequency and amplitude of damping vibrations have been determined utilizing the output voltage of the SPVS without any power source. Thus, SPVS might be useful in detecting low frequency vibrations in self-powered mode. (paper)

[en] Estimating a vector from noisy linear measurements often requires use of prior knowledge or structural constraints on for accurate reconstruction. Several recent works have considered combining linear least-squares estimation with a generic or ‘plug-in’ denoiser function that can be designed in a modular manner based on the prior knowledge about . While these methods have shown excellent performance, it has been difficult to obtain rigorous performance guarantees. This work considers plug-in denoising combined with the recently-developed vector approximate message passing (VAMP) algorithm, which is itself derived via expectation propagation techniques. It shown that the mean squared error of this ‘plug-and-play’ VAMP can be exactly predicted for high-dimensional right-rotationally invariant random and Lipschitz denoisers. The method is demonstrated on applications in image recovery and parametric bilinear estimation. (ml 2019)