Photocatalytic degradation of azo dye Orange II in aqueous solutions using copper-impregnated titania

During dyeing process, industries consume large quantity of water and subsequently produce large volume of wastewater. This wastewater is rich in color and contains different dyes. Orange II is one of them. In this article, metal-impregnated TiO₂ P-25 catalyst was used to enhance the photocatalytic degradation of Orange II dye. Photodegradation percentage was followed spectrophotometrically by the measurements of absorbance at λ _max = 483 nm. The effect of copper-impregnated TiO₂ P-25 photocatalyst for the degradation of Orange II has been investigated in terms of percentage removal of color, chemical oxygen demand (COD) and total organic carbon (TOC). As such 98 % color removal efficiency, 97 % percentage removal of COD and 89 % percentage removal of TOC was achieved with TiO₂ P-25/Cu catalysts under typical conditions. Copper-impregnated TiO₂ P-25 photocatalyst showed comparatively higher activity than UV/H₂O₂ homogeneous photodegradation. The relative electrical energy consumption for photocatalytic degradation was considerably lower with TiO₂ P-25/Cu photocatalyst than that with homogeneous photodegradation. Transmission electron microscopic analysis was used for catalyst characterization.     

Fault rupture directivity of large earthquakes in Himalaya

The paper examines the predominant fault rupture directivity during large earthquakes in different sectors of the Himalaya which influences strong ground motion and damage scenario. The nature of the faulting of earthquakes vis-à-vis their rupture directivity has been discussed. It is found that the rupture directivity near the Indo-Eurasian plate boundary varies from place to place i.e. either along the strike direction of the faults or at right angles to it. The secondary meizoseismal areas as observed for 1505 Dharchula, 1803 Uttarakhand, 1905 Kangra earthquakes in the Himalaya and 2001 Bhuj earthquake in stable continental region suggest that they are a fairly good indicator of predominant rupture directivity since the latter accentuates the site response up to a longer distance. The resulting larger ground motions, therefore, need to be incorporated in the design of engineering structures by suitable modifications in the BIS code.     

An assessment of seismicity parameters in northwest Himalaya and adjoining regions

In this study, an assessment of seismicity parameters in the northwest Himalaya and adjoining regions using an earthquake catalog from India Meteorological Department covering a period from June 1, 1998 to June 30, 2011 has been carried out. The spatial distributions of seismicity parameters, namely magnitude of completeness, M _C, a value, b value, and correlation fractal dimension, D _C, are estimated for the studied region. The M _C, a, and b values are found to be 2.5, 4.601, and 0.83, respectively. Despite significant gaps, the spatial distributions of a and b values are seen to follow similar trend and are found scattering in between Main Boundary Thrust (MBT) and South Tibet Detachment, adjoining areas of Mahendragarh-Dehradun Fault (MDF), Delhi-Haridwar Ridge (DHR) and Moradabad Fault (MF), and the southern flank of Karakoram Fault and Indus-Tsangpo Suture Zone. The estimated spatial distribution of b and a values is within 90 % of confidence level, thereby indicating non-uniform stress accumulation or higher rock fracturing density in the studied region caused by strong tectonization following several earthquakes. Negative correlation between low b value and high D _C is observed predominantly in the region between the MBT and Munsiari Thrust or Main Central Thrust-I of Garhwal and Kumaon Himalaya, adjoining zones of MDF, DHR, and MF of Indo-Gangetic plain, and the eastern flank of the studied region, suggesting the presence of asperities in the zone. At the same time, active creeping process can be inferred in between the MBT and Main Central Thrust of Garhwal Himalaya and the surrounding areas of Shimla region of the Himalayan arc to the northwestern part of the studied region from the positive correlation between b value and D _C. The results indicate that the structural heterogeneity caused by different stress accumulation and rock fracturing densities exists due to continuous tectonic adjustments between different geomorphic features of the studied region. An attempt has also been made to classify the studied region into smaller seismic zones by observing the spatial patterns of b value and D _C that are fractal properties of the observed seismicity, along with the prevalent fault networks.     

Seismotectonic study of Kishtwar region of Jammu Province using local broadband seismic data

Two moderate earthquakes of Mw 5.7 on the first of May and Mw 5.2 on the second of August occurred in the Kishtwar region in the year 2013. Our broadband seismic observatories located in the region recorded these events and the aftershocks. We analyzed these data to understand the seismotectonics of this region. Most of the events were located between 33.03° to 33.29° N latitude and 75.40° to 76.07° E longitude. Focal depths of these shallow earthquakes range from 7 to 12 km and are confined between Panjal Thrust (PT) and Kishtwar Window (KW). Spectral analysis of these events reveals that stress drop, source radius, corner frequency, and moment magnitude varied between 3.3 and 70.1 bars, 0.121 and 3.55 km, 0.397 and 6.06 Hz, and Mw 2.2 and Mw 5.7, respectively. The low stress drop of small-magnitude earthquakes reveals the brittle nature of the upper crust which is coincident with the field observations. The variation of stress drop with magnitude shows positive correlation whereas no such relation was observed between stress drop and depth of focus. The b value calculated (0.83) for the area reveals high stress accumulation within the incompetent rock zones in the area.     

Simulation of strong ground motion for a potential Mw7.3 earthquake in Kopili fault zone,northeast India

Natural Hazards - The occurrence of major natural disasters in recent years has impacted large cities worldwide and boosted the need of assessing urban resilience. As a key factor of resilience,...     

Effect of electron temperature on small-amplitude electron acoustic solitary waves in non-planar geometry

Effects of electron temperature on the propagation of electron acoustic solitary waves in plasma with stationary ions, cold and superthermal hot electrons is investigated in non-planar geometry employing reductive perturbation method. Modified Korteweg–de Vries equation is derived in the small amplitude approximation limit. The analytical and numerical calculations of the KdV equation reveal that the phase velocity of the electron acoustic waves increases as one goes from planar to non planar geometry. It is shown that the electron temperature ratio changes the width and amplitude of the solitary waves and when electron temperature is not taken into account,our results completely agree with the results of Javidan & Pakzad (2012). It is found that at small values of \(\tau \), solitary wave structures behave differently in cylindrical (\(\text {m} = 1\)), spherical (\(\text {m} = 2\)) and planar geometry (\(\text {m} = 0\)) but looks similar at large values of \(\tau \). These results may be useful to understand the solitary wave characteristics in laboratory and space environments where the plasma have multiple temperature electrons.