Titanium–vanadium oxide nanocomposite thin films: Synthesis,characterization and antibacterial activity

A sol–gel based deposition method was successfully developed to produce a series of crack-free, spatially homogeneous undoped/silver doped titania–vanadia oxide nanocomposite thin films. Thin films were characterized using Glancing Incidence X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Ultraviolet Visible Spectroscopy (UV–Vis). It was determined via both XRD and XPS that when calcined at 450 °C the nanocomposite crystallinity was a function of sol composition. Additionally, it was determined via GIXRD that upon silver doping, silver was incorporated into the vanadia structure or present in silver oxide form in crystalline films. A red shift within the UV–Vis spectra was observed with an increase of vanadia concentration from 0 to 100% respectively. Antibacterial analysis conducted on Escherichia coli and Staphylococcus epidermidis demonstrated that films exposed to light showed greater antibacterial properties.     

Suggested diagnostic reference levels for paediatric X-ray examinations in India

Exposure of children to ionising radiation is considered to carry higher risk than that of adults; therefore a need to suggest diagnostic reference levels (DRLs) for the common paediatric diagnostic X-ray procedures was recognised for the X-ray machines meeting the requirements of the recently implemented Safety Code for Medical Diagnostic X-ray Equipment and Installations in India. Measurements were carried out for entrance surface air kerma (free in air) in conventional paediatric X-ray diagnostic examinations among four age groups: <1, 1-4, 5-9 and 10-15 y. A total of 2240 air kerma measurements at different fixed focus to skin distances were studied for 7 paediatric diagnostic examinations with 11 different projections on 62 X-ray machines installed in 22 selected hospitals in the country. The third quartile values of air kerma per paediatric examination for the age group of 5-9 y were considered as values of paediatric DRLs. The suggested values of DRLs are 0.2 mGy for chest AP/PA, 0.3 mGy for chest LAT, 0.7 mGy for lumber spine AP, 1.3 mGy for lumber spine LAT, 0.3 mGy for thoracic spine AP, 0.6 mGy for thoracic spine LAT, 0.5 mGy for abdomen AP, 0.7 mGy for pelvis AP, 0.6 mGy for skull PA, 0.5 mGy for skull LAT and 0.8 mGy for hip joints AP.     

Vertically aligned ZnO nanowire arrays in Rose Bengal-based dye-sensitized solar cells

We fabricate dye-sensitized solar cells (DSSC) using vertically oriented, high density, and crystalline array of ZnO nanowires, which can be a suitable alternative to titanium dioxide nanoparticle films. The vertical nanowires provide fast routes or channels for electron transport to the substrate electrode. As an alternative to conventional ruthenium complex, we introduce Rose Bengal dye, which acts as a photosensitizer in the dye-sensitized solar cells. The dye energetically matches the ZnO with usual KII₂ redox couple for dye-sensitized solar cell applications.     

Low noise wide bandgap SiC based IMPATT diodes at sub-millimeter wave frequencies and at high temperature

We have presented a comparative account of the high frequency prospective as well as noise behaviors of wide-bandgap 4H-SiC and 6H-SiC based on different structures of IMPATT diodes at sub-millimeter-wave frequencies up to 2.18 THz. The computer simulation study establishes the feasibility of the SiC based IMPATT diode as a high power density terahertz source. The most significant feature lies in the noise behavior of the SiC IMPATT diodes. It is noticed that the 6H-SiC DDR diode shows the least noise measure of 26.1 dB as compared to that of other structures. Further, it is noticed that the noise measure of the SiC IMPATT diode is less at a higher operating frequency compared to that at a lower operating frequency.     

Shear waves in a fluid saturated elastic plate

In the present context, we consider the propagation of shear waves in the transverse isotropic fluid saturated porous plate. The frequency spectrum for SH-modes in the plate has been studied. It is observed that the frequency of the propagation is damped due to the two-phase character of the porous medium. The dimensionless phase velocities of the shear waves have also been calculated and presented graphically. It is interesting to note that the frequency and phase velocity of shear waves in porous media differ significantly in comparison to that in isotropic elastic media.     

Wavelet fuzzy combined approach for fault classification of a series-compensated transmission line

Series capacitor protected by metal-oxide varistor and air-gap arrangement imposes problems to line protection and other online decisions. Discrete wavelet transform integrated with a fuzzy logic system is designed for fault classification of a transmission line possessing a series capacitor at the midpoint. The approach uses information obtained from the wavelet decomposition of current signals for faulty phase selection and section identification. Two different FLSs are designed for the two classification objectives in this paper.     

Chronic phenytoin induced impairment of learning and memory with associated changes in brain acetylcholine esterase activity and monoamine levels

Groups of adult, male, Wistar rats were administered phenytoin (DPH) at 5, 12.5, 25, 50, or 75 mg/kg i.p. for 21 days. The learning and memory of these rats were assessed using the T-maze and passive avoidance tests. The plasma DPH levels, acetylcholine esterase (AChE) activity in different brain regions, and the levels of monoamines in the hippocampus were measured. The results indicate that DPH below the therapeutic plasma level did not significantly impair learning and memory. Correspondingly, no changes were noted in the brain 5-HT or AChE activity. However, DPH, at therapeutic plasma concentrations (i.e., 10.5 micrograms/ml in the dosage range of 50 and 75 mg/kg, respectively), significantly impaired learning and memory in rats. The impaired learning and memory functions were associated with increased 5-HT levels and decreased AChE activity in the hippocampus. With a dose of 75 mg/kg DPH, there was a reduction in the AChE activity in the striatum, in addition to hippocampus. It is conjectured that the neurochemical changes brought about by DPH at therapeutic plasma levels may account for the impairment of learning, memory, and cognitive functions in epilepsy.     

Kinetics of alkylation of phenol with methanol over Ce-exchanged NaX zeolite

The alkylation of phenol with methanol was investigated in vapor phase over a series of cerium-exchanged NaX zeolite with Ce loadings ranging from 0 to 10.43 wt%. The catalyst MX-4 with 8.86 wt% cerium was found to be the best one with total cresols selectivity of 72% at a temperature of 573 K and MeOH to phenol mole ratio of 4:1. The catalyst was also found to be quite stable in the operating range investigated. It was established that the stronger acid sties are required for C-alkylation compared to O-alkylation. From the study of the effects of various parameters, the optimum operating condition for highest cresols selectivity were determined as: MeOH to phenol mole ratio, 4:1; temperature, 623 K; space-time, 10.2 kg h/kgmole under atmospheric pressure. From the kinetic analysis of the experimental data, the apparent activation energy for the reaction was determined as 57.2 kJ/mole.