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The dysprosium (Dy) (1.12, 2.24, 3.33 and 4.02 at.%) modified zinc oxide (ZnO) nanoparticles were synthesized by simple chemical co-precipitation method. The prepared nanoparticles were analyzed by EDAX, TEM, FTIR, EPR, VSM and dielectric studies. The energy dispersive analysis of X-rays confirms the presence of Dy, Zn and O in the prepared samples. The transmission electron micrographs of the prepared samples show that the particles are spherical in nature with average size 22–18 nm. The shifting of Zn–O peak towards lower frequency side in the FTIR spectra of the prepared samples confirms the substitution of Dy ion in the ZnO lattice. EPR investigations exhibit paramagnetic signals at g- 1.956, 2.04 and 2.323. The magnetic properties of the synthesized Dy doped ZnO NPs reveal weak ferromagnetic behavior. The studies on electrical properties of the prepared samples provided new and interesting information on the contribution of grains, grain boundaries and interfacial polarization on dielectric parameters and electrical conductivity.

Ce-doped ZnO nanoparticles (NPs) with different Ce doping concentrations (0, 0.96, 1.96, 2.52 and 3.12 at.% of Ce) were prepared by the chemical co-precipitation method. Energy-dispersive analysis of X-rays confirms the presence of Ce in Ce-doped ZnO nanoparticles. Raman spectra revealed the hexagonal wurtzite structure of pure and Ce-doped ZnO nanoparticles and presence of various defects. The photoluminescence spectra exhibited enhanced violet and blue emission peak intensities for 0.96 at.% of Ce, while broad band green emissions decreased with Ce content. Electron paramagnetic resonance (EPR) studies revealed the presence of oxygen vacancies (V O), zinc vacancies (V Zn) and Ce3+ ions in the prepared ZnO nanoparticles. VSM studies showed room temperature ferromagnetism (RTFM) in the Ce-doped ZnO NPs. The substituted Ce3+ions found to induce RTFM along with V O, V Zn in correlation with the results obtained from the EPR, PL and Raman studies. The variation of dielectric constants (e r), dielectric loss (e″) and ac conductivity (σ ac) as a function of frequency and Ce concentration is studied using ‘Maxwell–Wagner Model.’

Ultrasonic and microwave-assisted practical methods have been developed for the nitration of phenols using metal nitrates in aqueous polyethylene glycol (PEG) media. Solvent is recycled three times for reproducibility. It was recycled with minimum loss and decomposition. Developed protocols were cost effective, simple and efficient, which afforded nitration products in good to excellent yields. The observed hyperchromic/hypochromic shifts in the UV/VIS spectra of metal nitrates in PEG solutions could be due to the plausible in situ formation of “PEG-bound M(II) nitrate” and thereby the release of nitronium ion () during the course of reaction when metal nitrate [M(II)nitrate] is added to PEG. Nitronium thus formed most likely is captured by aromatic compound to afforded nitro aromatics.

This research work presents the synthesis, characterization, evaluation of the antibacterial and anticancer activity of ZnO nanopowders prepared by solution combustion method using the bio fuels Punica granatum L and Tamarindus indica L. The X-ray diffractograms of all the samples revealed the hexagonal Wurtzite structure with the standard JCPDS pattern of zincite [36–1451]. Surface morphology of the samples was studied by SEM. Particle shapes and sizes were determined by TEM. Qualitative phytochemical screening of the aqueous fruit extracts of Punica granatum L and T. indica L revealed the presence of many phyto-components in them. Toxicity of the nanopowders was tested on Gram-negative Escherichia coli MTCC 7410 and Pseudomonas aeruginosa MTCC 7903 by disk diffusion method. Minimum inhibitory concentration was determined by microbroth dilution technique. Anticancer activity of ZnO powders was tested against breast cancer cell line MCF-7 by MTT assay. The cytotoxicity was assessed by hemolytic activity.

Pure and erbium (1.30, 1.79, 2.83 and 3.53 at. %) doped ZnO nanoparticles are synthesized by wet chemical co - precipitation method. The synthesized s amples are characterized by powder X - ray diffraction (XRD), energy - dispersive analysis of X - rays (EDAX), transmission electron microscopy (TEM), Raman spectroscopy, UV - visible diffusion reflectance spectroscopy (DRS) and LCR Impedance spectroscopy. The XRD measurements confirmed the hexagonal wurtzite structure of all samples and size of the particle is found to be decreased with Er content. TEM images show spherical shape with more agglomeration in Er doped ZnO nanoparticles. Raman spectra confirmed the he xagonal wurtzite structure of pure and Er doped ZnO nanoparticles with E 2 (high) mode at 438 cm - 1 and presence of other possible defects. UV - visible DRS shows decrease in the band gap with increasing Er 3+ in ZnO host. Dielectric constant, dielectric loss f actor and ac conductivity properties were decreased with Er

Pure and Dy(1.15, 2.24, 3.33 and 4.02 at.%)-doped ZnO nanoparticles were prepared by the chemical co-precipitation method. The as prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA-DTA), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) studies. XRD studies confirm both undoped and Dy-doped ZnO nanoparticles reveal wurtzite structure with average grain size in the range of 24–16 nm and are in agreement with TEM analysis. EDS confirms the presence of Dy in Dy-doped ZnO nanoparticles. Raman studies, confirm the wurtzite structure of ZnO nanoparticles besides increase in defects with doping concentration. UV–Vis DRS measurements indicated a blue shift optical band gap with Dy-doping. PL spectrum demonstrated immense enhanced green emission which attributes to the increase in defects concentration. The emissions intensity could be tuned by varying the Dy concentration and excitation wavelength as well for the application of better optoelectronic devices.

Modern manufacturers, seeking to remain competitive in the market, rely on their Manufacturing engineers and production personnel to quickly and effectively set up manufacturing processes for new products. This paper presents the multi response optimization of turning parameters for Turning on AISI 4340 Alloy Steel. Experiments are designed and conducted based on Taguchi’s L27 Orthogonal array design. This paper discusses an investigation into the use of Taguchi parameter Design and Regression analysis to predict and optimize the Surface Roughness, Metal Removal Rate and Power Consumption in turning operations using CVD Cutting Tool. The Analysis of Variance (ANOVA) is employed to analyze the influence of Process Parameters during Turning. This paper also remarks the advantages of multi-objective optimization approach over the single-objective one. The useful results have been obtained by this research for other similar type of studies and can be helpful for further research works on the Tool life and Vibration of tools etc.

Intense photo and mechanoluminescent (ZnS) 1− x (MnTe) x powder samples with x = 0.02, 0.05, 0.10, 0.15, 0.20 and 0.25 were prepared by simple solid state reaction method. All samples were polycrystalline with wurtzite structure. Wurtzite lattice parameters increased with composition ‘ x ’ linearly obeying Vegard's law. Both in photoluminescence and in mechanoluminescence an emission band was observed in red region at 650 nm. The band gap of the samples decreased with increase of composition ‘ x ’. Metal–Semiconductor transition was observed in all (ZnS) 1− x (MnTe) x samples. The activation energies of the samples were found to be in the range 65–89 meV.

The friction damping concept is widely used to reduce resonance stresses in gas turbines. A friction damper has been designed for high pressure turbine stage of a turbojet engine. The objective of this work is to find out effectiveness of the damper while minimizing resonant stresses for sixth and ninth engine order excitation of first flexure mode. This paper presents a methodology that combines three essential phases of friction damping optimization in turbo-machinery. The first phase is to develop an analytical model of blade damper system. The second phase is experimentation and model tuning necessary for response studies while the third phase is evaluating damper performance. The reduced model of blade is developed corresponding to the mode under investigation incorporating the friction damper then the simulations were carried out to arrive at an optimum design point of the damper. Bench tests were carried out in two phases. Phase-1 deals with characterization of the blade dynamically and the phase-2 deals with finding optimal normal load at which the blade resonating response is minimal for a given excitation. The test results are discussed, and are corroborated with simulated results, are in good agreement.

The Ignition Over Pressure (IOP) is an unsteady pressure wave generated by the ignition of solid rocket motor during launch vehicle lift-off. This wave behaves as a blast or a shock wave followed by a low frequency excitation characterized up to 40 Hz, would cause severe damage to the launch vehicle, its structures and surroundings. However, in case of huge propulsion system, having two solid rocket motors as its boosters, due to the skew in their ignition, during lift-off, the phase difference of the wave from one side of the vehicle to the other could cause a severe moment, which is detrimental to the vehicle. The present paper deals with the occurrence of such blast waves during the testing of various scaled down solid rocket motors. Also, an attempt has been made experimentally to characterize and understand the propagation of the IOP wave causing unsteady pressure oscillations and transient pressure rise in the vicinity of a solid rocket motor. The spectral and directional characteristics of the IOP wave are also highlighted. Typical scaled-down solid rocket motors with and without nozzle shutters have been tested in horizontal firing configuration and the results are compared to study their effect. The resulting shock wave propagation has axial downstream as well as angular directivities. The pressure rise rate in the chamber is found to be directly correlated to the over pressure measured at various locations at the downstream of the nozzle.