A comprehensive review on recent material development of passive direct methanol fuel cell

Direct methanol fuel cells (DMFCs) within all types of fuel cells are the most viable alternative to lithium-ion batteries in the portable application and recently attracted much attention. This study reviews on passive DMFC material development with emphasis on to the performance activity, cost, durability and stability aspect. This paper has reported the basic desirable characteristics of each component with their material development. This paper has reviewed all possible materials of passive DMFC component, which can make the passive DMFC compact and feasible energy source in the future.     

Observation of grain growth in swift heavy ion irradiated NiO thin films

NiO thin films grown on Si(100) substrates by electron beam evaporation, were sintered at 500 °C and 700 °C. The films were irradiated with 120 MeV Au⁹⁺ ions. Irradiation had different effects depending upon the initial microstructure of the films. Irradiation of the films at a fluence of 3 × 10¹¹ ions cm⁻² leads to grain growth for the films sintered at 500 °C and grain fragmentation for the films sintered at 700 °C. At still higher fluences of irradiation, grain size in 500 °C sintered film decreased, but the same improved in 700 °C sintered film. Associated with the grain size, texturing of the films was also shown to undergo significant modifications under irradiation.     

Mechanism of polymer drag reduction using a low-dimensional model

Using a retarded-motion expansion to describe the polymer stress, we derive a low-dimensional model to understand the effects of polymer elasticity on the self-sustaining process that maintains the coherent wavy streamwise vortical structures underlying wall-bounded turbulence. Our analysis shows that at small Weissenberg numbers, Wi, elasticity enhances the coherent structures. At higher Wi, however, polymer stresses suppress the streamwise vortices (rolls) by calming down the instability of the streaks that regenerates the rolls. We show that this behavior can be attributed to the nonmonotonic dependence of the biaxial extensional viscosity on Wi, and identify it as the key rheological property controlling drag reduction.     

Fabrication of a nanostructured gold-polymer composite material

A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl₄ as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent for both the AP and the water solution of HAuCl₄. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the reduction of AuCl₄ ^- results in the formation of gold nanoparticles (∼ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the composite material.     

Formation of palladium nanoparticles in poly (o-methoxyaniline) macromolecule fibers: An in-situ chemical synthesis method

We report here a novel in-situ synthetic method for the preparation of poly (o-methoxyaniline) and palladium nanoparticle composite material. Ortho-Methoxyaniline and palladium acetate were used as the precursors; during the reaction o-methoxyaniline was oxidized and forms poly (o-methoxyaniline) and palladium acetate is reduced forming palladium nanoparticles. IR and Raman spectra provide information on the structure of the polymer. The TEM and SEM analysis are used to determine the size of the nanoparticles and the morphology of the polymer respectively.     

Effect of time dependent morphological parameters of nanoclusters on perikinetic heat conduction and induced micro-convection mechanisms of oxide based nanofluids

The article represents an experimentally supported quantitative analysis to observe the effect of time, temperature, nanoclusters’ morphology, and instantaneous volume fractions on perikinetic heat conduction and Brownian motion-based induced convection mechanisms of oxide (Al₂O₃ and TiO₂, size 25–30 nm) based nanofluids. The appropriate models of thermal conductivity have been introduced to study the effect of various parameters such as; varying volume fractions, suspensions’ stabilities, nanoclusters’ growth, temperature, and the liquid layering. The developed model could predict the thermal conductivity enhancements of nanofluids within the accuracy of ± 0.5% to ± 4.5.0% in the temperature range from 20°C to 50°C.

Abbreviations: DI: De-ionized water; DLS: Dynamic light scattering; XRD: X-rays diffraction; TEM: Transmission electronic microscope; SDBS:Sodium dodecyl benzene sulphonate.

Figure Effect of temperature on the Brownian Reynold number for Al₂O₃-H₂O and TiO₂-H₂O nanofluids.     

Bidirectional carrier aggregation in next-generation radio-over-fiber heterogeneous network based on FBMC

We have projected and verified a bidirectional intra-/inter-radio-access-technology carrier-aggregation method for a next-generation heterogeneous mobile network supported by filter bank multicarrier(FBMC). Successful transmission of intra/inter-band carrier aggregation between five broadband FBMC signals and three bands 4G long-term-evolution-advanced signal over 50 km single-mode fiber plus 10 m free-space is successfully broadcasted by employing an incoherent light-injection scheme in downlink. In uplink, two intra-bands carrier-aggregated wireless local area network Institute of Electrical and Electronics Engineers 802.11 g signal is carried over the equal distance. High receiver sensitivity, low error vector magnitude, and clear constellation diagrams show successful delivery of different wireless services for different consumers. Therefore, the proposed hybrid system should become a potential solution for a future mobile front-haul network because of its low latency and high capacity.     

Coumarinolignans with Reactive Oxygen Species (ROS) and NF-κB Inhibitory Activities from the Roots of Waltheria indica

Seven new coumarinolignans, walthindicins A–F (1a, 1b, 2–5, 7), along with five known analogs (6, 8–11), were isolated from the roots of Waltheria indica. The structures of the new compounds are determined by detailed nuclear magnetic resonance (NMR), circular dichroism (CD) with extensive computational support, and mass spectroscopic data interpretation. Compounds were tested for their antioxidant activity in Human Cervical Cancer cells (HeLa cells). Compounds 1a and 6 showed higher reactive oxygen species (ROS) inhibitory activity at 20 μg/mL when compared with other natural compound-based antioxidants such as ascorbic acid. Considering the role of ROS in nuclear-factor kappa B (NF-κB) activation, compounds 1a and 6 were evaluated for NF-κB inhibitory activity and showed a concentration-dependent inhibition in Human Embryonic Kidney 293 cells (Luc-HEK-293).     

Electronic and vibrational spectra of diphenylmethane

From the critical analyses of Raman and infrared spectra, different normal modes of vibration of diphenylmethane (DPM) have been identified. The near ultraviolet absorption spectra of the molecule are found to consist of two band systems, one around 220 nm and the other around 270 nm with respective f-values 5.23 x 10(-2) and 6.44 x 10(-3). The first system is broad and shows few diffuse structures, whereas the later one exhibits very well-resolved structure. They are respectively assigned as 1L(a) and 1L(b) bands. The Raman excitation profiles of several normal modes have been analyzed to get structural and other information of different excited electronic states.