Suppression of defect level emissions in low temperature fabricated one-dimensional Mn doped ZnO nanorods

One-dimensional Mn doped ZnO nanocrystallites were synthesized through a facile low temperature surfactant free chemical route. The crystallite structure and morphological evolution of the particles were revealed to be of wurtzite phase and rod like structures from the X-ray diffraction and transmission electron microscopic analysis, respectively. Using Raman spectroscopy the role of oxygen related defects and phase purity in the Mn substituted ZnO systems were studied systematically. A significant suppression in the sub-band edge emission was visualized in the room temperature emission spectra of the Mn doped systems. The intensity ratio in between the near-band edge and defect-level emissions was observed to increase, signifying the reduction in oxygen related defects and revealing their influence on the crystallinity on the Mn substituted ZnO species. These variations were correlated with the increasing number of Mn ions in the host lattice, which results with their passivating action on the surface defects.     

Thermooptic two-mode interference device for reconfigurable quantum optic circuits

Reconfigurable large-scale integrated quantum optic circuits require compact component having capability of accurate manipulation of quantum entanglement for quantum communication and information processing applications. Here, a thermooptic two-mode interference coupler has been introduced as a compact component for generation of reconfigurable complex multi-photons quantum interference. Both theoretical and experimental approaches are used for the demonstration of two-photon and four-photon quantum entanglement manipulated with thermooptic phase change in TMI region. Our results demonstrate complex multi-photon quantum interference with high fabrication tolerance and quantum fidelity in smaller dimension than previous thermooptic Mach–Zehnder implementations.     

Colloidal synthesis of Gd<Superscript>3+</Superscript> doped ZrO<Subscript>2</Subscript> based dielectrics and their structural and electrochemical property studies

Solution processed wide band gap dielectrics have nowadays started to receive renewed interest for practical application in semiconductor electronics. In this regard, undoped and gadolinium (Gd) doped zirconia (ZrO₂) nanocrystallites were colloidally processed and their potential for dielectric applications has been demonstrated. X-ray diffraction measurements revealed the effective crystallization of nanostructures and the successful substitution of Gd ions into the cubic ZrO₂ matrix. The particulate-like characteristics of undoped and Gd doped ZrO₂ nanostructures were examined through the electron microscopes, which hardly revealed any difference among them. The optical band gap of ZrO₂ nanostructures was determined to be around 4.64–4.80 eV from the absorbance measurements. The potential of Gd doped ZrO₂ nanostructures for dielectric functions were evaluated through electrochemical impedance spectroscopic measurements. The improved capacitance values estimated from the Nyquist plots suggests the potential of the investigated materials for low power and low voltage electronic applications.     

Development of an Innovative Bituminized Jute Paving Fabric (BJPF) Along with its Commercial Field Trials for Potential Application in the Field of Geotechnical Construction with an Eye Towards Global Concern

In the last quarter of the twentieth century, a new class of materials, Geosynthetics, emerged prospectively leading significant innovation in the design of geotechnical and geoenvironmental systems. Geotextiles have proven to be among the most versatile and techno-economically viable ground modification materials playing a significant role in modern pavement design and maintenance techniques. With the growing environmental concern across the globe, technologists, researchers have inclined towards the natural geotextile where Jute Geotextile (JGT) is one of the potential candidates. But, JGT has been restricted mainly as underlay in road construction. Hence, there is an urgent need to design and develop a precise innovative fabric as overlay on existing pavements and other emerging civil works to stay technically and economically competitive in the global market. Such a fabric will not only prove techno-economically viable but will also reduce the carbon foot-print generation to a large extent. This paper delineates the development of Grey Jute Paving Fabric (GJPF) followed by its bituminization with suitable type and grade of bitumen to develop Bituminized Jute Paving Fabric (BJPF). The BJPF will enhance the life of the overlay thereby reducing the cost of maintenance as well as serving as a partial substitute of bitumen mastic.     

Catalytic properties of dispersed iron oxides Fe2O3/MO2 (M = Zr,Ce, Ti and Si) for sulfuric acid decomposition reaction: Role of support

Supported iron oxides have been established as an important class of catalyst for high temperature sulfuric acid decomposition. With an objective to elucidate the role of support in modifying the overall catalytic properties of dispersed iron oxide catalysts, a series of supported iron oxide based catalysts, Fe₂O₃ (15 wt%)/MO₂ (M = Zr, Ce, Ti and Si), synthesized by adsorption-equilibrium method, is investigated for sulfuric acid decomposition reaction. The structure of dispersed iron oxide phases largely depended on the nature of the support oxide as revealed by the XRD and Mössbauer studies. α-Fe₂O₃ is found to be present as a major phase on ZrO₂ and CeO₂ support while ε-Fe₂O₃ was the major phase on silica supported iron oxide. On the other hand, presence of mixed oxide Fe₂TiO₅ was revealed over TiO₂ support. Strong dispersed metal oxide-support interactions inhibited the total reduction of the dispersed phase on SiO₂ and TiO₂ as compared to complete reduction of dispersed iron oxide on CeO₂ and ZrO₂ supports during temperature programmed reduction upto 1000 °C. The order of catalytic activity at a temperature of ～750 °C is observed as Fe₂O₃/SiO₂ > Fe₂TiO₅/TiO₂ > Fe₂O₃/ZrO₂ > Fe₂O₃/CeO₂, while at higher temperatures of ～900 °C the SO₂ yield is found to be comparable for all catalysts. A relationship between the rate of sulfate decomposition and catalytic activity is established through detailed TG-DTA investigations of sulfated catalyst and support. Considerable influence of the support oxide on the composition, structure, redox properties, morphology and catalytic activities of the active iron oxide dispersed phase has been observed. Thus, the support oxides operate as a critical component in the complex supported metal oxide catalysts and these findings might influence the design and development of future high temperature sulfuric acid decomposition catalysts.     

An improved method for R-peak detection by using Shannon energy envelope

R-peaks in electrocardiogram (ECG) play a vital role in diagnosis of heart rhythm irregularities and also estimating heart rate variability. However, almost all existing R-peak detectors suffer from the non-stationary of both QRS morphology and noise. To overcome these difficulties, we propose a four-stage improved method to detect R-peak using Shannon energy envelope. In the first stage, noise is suppressed and QRS complex is enhanced by using band pass filter, first order differentiation, and amplitude normalization. In the second stage, Shannon energy envelope is extracted. In the third stage, peak is estimated without considering any threshold amplitude. In the final stage, true R-peaks are detected. Our proposed R-peak detection method is validated using 48 first channel ECG records of the MIT-BIH arrhythmia database with the accuracy of 99.84%, sensitivity of 99.95% and positive predictability of 99.88%. Our proposed method outperforms other well-known methods in case of pathological ECG signals.     

Bio-accumulation of metals on reef associated organisms of Lakshadweep Archipelago

Tissue samples of marine organisms from the coastal waters of Agatti Island were subjected to analysis of metals (cadmium, cobalt, copper, iron, magnesium, manganese, nickel, lead and zinc), using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) for the assessment of the present condition of the Island ecosystem and compiling the baseline data for future monitoring, with respect of metal accumulation of marine organisms. Tissue samples of fish, shellfish and seaweed revealed that the metals have different levels of accumulation viz. Cd = 0.08-0.14, Co = 0.01-0.02, Cu = 0.16-0.98, Fe = 3.19-5.3, Mg = 86.73-152.45, Mn = 0.17-0.55, Ni = 0.06-0.26, Pb = 0.11-0.46 and Zn = 3.26-14.2 μg g⁻¹ dry wt. Metal concentrations were more in shellfish and less in finfish. Concentrations of toxic metals such as Cd, Co, Ni and Pb were well below the permissible limits proposed by the World Health Organization.