Investigation on Electrical and Dielectric Behaviour of Halloysite Nanotube Incorporated Polycarbonate Nanocomposite Films

Polycarbonate (PC) nanocomposites were fabricated by solution intercalation method with halloysite nanotubes (HNTs) as reinforcement. The effects of HNT content on the structural and dielectric properties were investigated. The properties of the fabricated films were probed with the intention to establish the consequence of nano-fillers on electrical characteristics/behaviours with PC. The incorporation of HNT generates notable performance enhancements through reinforcement effect. The electrical conductivity of polycarbonate got better when more than 4 wt% HNT is added. Interestingly, the integration of HNT significantly increases the dielectric permittivity of composite films with low dielectric loss which makes the nanocomposites attractive in practical applications such as electrical devices, electrical packaging and capacitors. Furthermore, the structural aspects were elucidated by X-Ray diffraction studies, Fourier transform infrared spectroscopy and dispersion of nanofillers in PC matrix were evaluated by scanning electron microscopy.     

Influence of Ball Burnishing Process on Equal Channel Angular Pressed Mg-Zn-Si Alloy on the Evolution of Microstructure and Corrosion Properties

Silicon - In the present study, Mg-4Zn-1Si alloy was subjected to equal channel angular pressing (ECAP) up to 4 passes at 300 °C, followed by ball burnishing using 0.3 mm...     

Structural,electrical and electrochemical behaviours of LiNi0·4 M 0·1Mn1·5O4 (M = Al,Bi) as cathode material for Li-ion batteries

In order to improve the cycling performance of LiMn₂O₄ based cathode materials, we have synthesized a new composition, LiNi_0·4 M _0·1Mn_1·5O₄ (M = Al, Bi), by the sol–gel method. The formation of solid solutions is confirmed by structural characterization using TG/DTA, XRD, FT–IR, EPR, SEM and EPR. A.c.-impedance (Nyquist plot) showed a high frequency semicircle and a sloping line in the low-frequency region. The semicircle is ascribed to the Li-ion migration through the interface from the surface layer of the particles to the electrolyte. Cyclic voltammogram (between 3·5 and 4·9 V) for these materials using CR2032 coin-type cell shows two pairs of redox peaks corresponding to two-step reversible intercalation process, wherein Li-ions occupy two different tetragonal 8a sites in spinel Li _x Mn₂O₄ (x < 1) lattice. The galvanostatic charge/discharge curves for M = Al (77 mAh g^–1) showed reasonably good capacity retention than that of M = Bi (11 mAh g^–1) at the end of 17th cycle.     

Green Synthesis of Zinc Oxide Nanoparticles (ZnO NPs) for Effective Degradation of Dye,Polyethylene and Antibacterial Performance in Waste Water Treatment

At present, there is a vital need for river water purification by developing new approaches to eliminate bacterial biofilms, textile dyes, and Low-Density Polyethylene (LDPE) plastics that pose severe threats to human and environmental health. The current work put forward the construction of an eco-friendly green strategy to synthesize zinc oxide nanoparticles (ZnO NPs) using areca nut (Areca catechu) extract and their application to tackle the challenges in water purification. Prepared biogenic NPs were characterized by X-ray diffraction analysis (XRD), Fourier Transform Infra-Red (FT-IR), Energy Diffraction Spectroscopy (EDS), Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM) analysis, confirmed the spherical shape in 20 nm and UV–vis spectroscopy. The characteristic absorption band exhibited at 326 nm confirmed the formation of ZnO NPs using UV–vis spectroscopy. Among all the tested bacterial pathogens, the E. coli at 50 µg/mL concentration showed the highest inhibition of biofilm activity, followed by the highest growth curve, cellular leakage, and potassium ion efflux. The ZnO NPs observed with photo-degradation of Rhodamine-B (Rh-B), Methylene Blue (MB), and Nigrosine dyes under sunlight irradiation at different time intervals. Finally, the photocatalytic activity of LDPE-ZnO NPs nanocomposite film showed the highest degradation under solar light irradiation were confirmed through photo-induced weight loss, SEM, FTIR, and MALDI-TOF analysis. This study demonstrates ZnO NPs exhibit efficacy against biofilm formation, degradation of photocatalytic textile dyes, and low-density LDPE film under solar light irradiation, which can be a step forward in water purification.

     

Studies on degradation of reactive textile dyes solution by electrochemical method

The indirect electrochemical degradation of industrial effluents has become an attractive method in recent years. This paper deals with the electrochemical degradation of Novacron Deep Red C-D (NDRCD) and Novacron Orange C-RN (NOCRN) reactive azo dyes from aqueous solution using graphite carbon electrodes. The results indicated that initial pH, current density and supporting electrolytes were played an important role in the degradation of dyes. Electrochemical behavior of reactive azo dyes has been studied with cyclic voltammetry in acidic medium using pencil graphite as working electrode. The potentials selected for the two dyes were in the range +1.0 to -0.4V and +0.5 to -0.2V, respectively. The CV, UV-Vis and chemical oxygen demand (COD) studies were selected to evaluate the degradation efficiency. The maximum colour removal efficiency of 99% and 97% and chemical oxygen demand (COD) removal efficiency of 88% and 82% could be achieved for CDRCD and COCRN, respectively at 7 g L(-1) of NaCl concentration. The LC-MS study revealed the degradation of both the dyes and confirmed that the azo groups and aromatic rings were destroyed. The results revealed the suitability of the present process for the effective degradation of dye effluents.     

High-frequency transistor amplifier analysis

In this paper, some modifications are suggested to the standard procedure for high-frequency analysis of transistor amplifiers using Miller's theorem. These suggestions remove a major stumbling block in the application of this theorem and extend the range of applicability of this method.     

Cytoprotective and antioxidant activity studies of jaggery sugar

Jaggery and other sugars namely white, refined and brown sugars were evaluated for cytoprotectivity on NIH 3T3 fibroblasts and erythrocytes, DPPH radical scavenging activity, reducing power and DNA protection. In addition, total phenol content and phenolic acid composition were also determined. Results indicated a total phenolic content of 26.5, 31.5, 372 and 3837 μg GAE/g for refined, white, brown and jaggery, respectively. The HPLC analysis revealed the presence of different phenolic acids in brown sugar and jaggery. On NIH 3T3 cells oxidation, at 4 mg/ml concentration, jaggery showed 97% protection compared to brown sugar, and both sugars effectively reduced erythrocyte oxidation. A dose dependent reducing power and DPPH radical scavenging activity was also observed for jaggery and brown sugar. An EC₅₀ of 7.81 and 59.38 μg/ml were observed for jaggery and brown sugar in the DPPH scavenging assay. In DNA oxidation studies, higher protection was observed in jaggery followed by brown, white and refined sugar treated samples.     

Cytoprotective and antioxidant activity of free,conjugated and insoluble-bound phenolic acids from swallow root (Decalepis hamiltonii)

Swallow root (Decalepis hamiltonii) was extracted for free (SRFP), conjugated (SRCP) and insoluble-bound phenolic acids (SRIBP), and evaluated for cytoprotectivity, 1,1,diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, reducing power and protection to DNA damage. In addition, the constituent phenolic acids in the extracts were also analysed. Results indicated a total phenol content of 20.72, 7.97 and 11.52 mg gallic acid equivalents (GAE)/g for SRFP, SRCP and SRIBP extracts, respectively. At 0.12 μg/mL concentration SRCP showed 87% cytoprotection (on NIH 3T3 cells) compared to SRFP (47%) and SRIBP (65%). DPPH radical scavenging activity indicated an IC₅₀ of 0.046, 0.06 and 0.128 μg/mL for SRCP, SRIBP and SRFP, respectively. Also, SRCP showed higher reducing power and DNA protectivity (80%). HPLC analysis of phenolic acid extracts showed the presence of hydroxybenzoate and cinnamate derivatives. Among the phenolics identified gallic, gentisic, protocatechuic and p-coumaric acids were the major contributors to antioxidant activity.