Assessment of water quality of River Ganges during Kumbh mela 2010

In the present study the water quality of Ganga River was assessed during Maha Kumbh-2010.  River water samples were collected from five sites.  Various Physico-Chemical and microbiological parameters were analysed. It was observed that all parameters were within the permissible limit according to WHO (2009) and BIS (2004) except most probable number that is the indication of low sanitary condition and it can further lead to the outbreak of diseases. During this mass bathing two sites were found to be more affected than the other three sites. These were noted to Har-ki-pauri and Mayapur ghat at Haridwar, at these sites parameters are observed to be slightly raised in comparison to other three sites

Influence of growth temperature on structural and optical properties of laser MBE grown epitaxial thin GaN films on a-plane sapphire

Epitaxial thin GaN films (similar to 60 nm) have been grown on a-plane sapphire substrates at different growth temperatures (500-700 degrees C) using laser molecular beam epitaxy (LMBE). The effect of growth temperatures on the structural and optical properties of GaN layers grown on low temperature (LT) GaN buffer on prenitridated a-sapphire have been studied systematically. The in situ reflection high energy electron diffraction pattern revealed the three-dimensional epitaxial growth of GaN films on a-sapphire under the adopted growth conditions. The full width at half maximum (FWHM) value of x-ray rocking curves (XRCs) along GaN (0002) and (10-12) planes decreases with increasing growth temperature. The FWHM values of (0002) and (10-12) XRC for the 700 degrees C grown GaN film are 1.09 degrees and 1.08 degrees, respectively. Atomic force microscopy characterization showed that the grain size of GaN increases from 30-60 to 70-125 nm with the increase in growth temperature as GaN coalescence time is shorter at high temperature. The refractive index value for the dense GaN film grown at 600 degrees C is obtained to be similar to 2.19 at the wavelength of 632 nm as deduced by spectroscopic ellipsometry. Photoluminescence spectroscopy confirmed that the epitaxial GaN layers grown on a-sapphire at 600-700 degrees C possess near band edge emission at similar to 3.39 eV, close to bulk GaN. The GaN growth at 700 degrees C without a buffer still produced films with better crystalline and optical properties, but their surface morphology and coverage were inferior to those of the films grown with LT buffer. The results show that the growth temperature strongly influences the structural and optical quality of LMBE grown epitaxial GaN thin films on a-plane sapphire, and a growth temperature of >600 degrees C is necessary to achieve good quality GaN films. Published by the AVS

AlGaN nanowall network structure grown on sapphire (0001) substrate by laser molecular beam epitaxy

Self-assembled AlGaN nanowall networks have been grown heteroepitaxially on sapphire (0001) substrate using laser molecular beam epitaxy (LMBE) technique. The effect of growth temperature on the formation of AlGaN nanowall network structure has been studied in the range of 500-700 degrees C. It is found that the growth of AlGaN under strong N-rich flux condition at a high growth temperature of 700 degrees C is conducive for the formation of self-assembled nanowall network. In-situ reflection high energy electron diffraction exhibits the three-dimensional growth of the AlGaN nanowall network structure oriented along c-axis. The nanowall width and pore size are measured to be 10-40 and 30-70 nm, respectively, by using field emission scanning electron microscopy. From room temperature photoluminescence measurement, a strong ultra-violet (UV) emission at about 3.52 eV due to band-to-band transition is obtained for the AlGaN nanowall structure with a high UV-to-yellow luminescence intensity ratio indicating a good optical quality. The grown AlGaN nanowall network is suitable for the applications in field emitters, photo-detectors and other nitride-based optoelectronic devices

Critical Review of Trends in GHG Emissions from Global Automotive Sector

Between 1906 and 2005, records show that global average air temperature near the earth’s surface increased by 0.74 ± 0.18°C. If emissions of greenhouse gases, and in particular CO2, continue unabated the enhanced greenhouse effect may alter the world’s climate system irreversibly. Total emissions of greenhouse gases, across all sectors, were 42.4 gigatonnes (Gt) of CO2-eq in 2005. Energy sector, accounts for 84% of global CO2 emissions and 64% of the world’s greenhouse-gas emissions. Energy-related CO2 emissions rise from 28.8 Gt in 2007 to 34.5 Gt in 2020 and 40.2 Gt in 2030. Global per-capita emissions of energy-related CO2 in 2007 was 4.4 tonnes. Higher growth of automobiles and consumption of petroleum products is invariably attended by concerns of pollution and climate changes. Global fleet of passenger light-duty vehicles (PLDVs) is estimated to increase from 770 million in 2007 to 1.4 billion in 2030. Among all sectors that emit CO2, the transport sector is the fastest growing, representing from 22% to 24% of global GHG emissions from fossil fuel sources, second only to the industrial sector. World emissions of NOx were 82 Mt in 2007, of which Road transport was responsible for about one-third of NOx emissions. Only Road transport related CO2 emission is estimated to increase from 4.8 Gt in 2007 to 6.9 Gt in 2030. The increase in CO2 emissions is largely a result of increasing demand for individual mobility in developing countries. There are strong efforts and renewed investments by manufacturers and suppliers in providing solutions to the CO2 reduction challenge. Low-carbon vehicles, such as hybrid cars, plug-in hybrids and electric cars, have received widespread public attention recently. It is estimated that share of hybrids in the global fleet will reach about 5% by 2020 and almost 8% by 2030, up from just 0.15% in 2007. Plug-in hybrids and electric cars will constitute only 0.2% of the global fleet in 2030. But increase in electricity consumption in road transport in future due to increased penetration of plug-in hybrids and electric vehicles, sees transport sector CO2 savings partially offset by power generation emissions. An estimated increase of 880 TWh of electricity consumption in transport in 2030, of which 90% occurs in PLDVs, will result in about 250 Mt of additional CO2 emissions. Authors forecasted that the use of environment-friendly and clean technologies is going to make all the difference between the winners and the losers of the industry. It is noted that current policies are insufficient to prevent a rapid increase in the concentration of greenhouse gases in the atmosphere. It is recommended that policy makers and researchers should give more emphasis on ‘cost-effectiveness as most important factor to reduce automotive GHG emission reduction’. It is also concluded that CO2 savings will be maximized if well-to-wheel impact is clearly addressed at all stages of the fuel and energy chain

Critical Review of Trends in GHG Emissions from Global Automotive Sector

Between 1906 and 2005, records show that global average air temperature near the earth’s surface increased by 0.74 ± 0.18°C. If emissions of greenhouse gases, and in particular CO2, continue unabated the enhanced greenhouse effect may alter the world’s climate system irreversibly. Total emissions of greenhouse gases, across all sectors, were 42.4 gigatonnes (Gt) of CO2-eq in 2005. Energy sector, accounts for 84% of global CO2 emissions and 64% of the world’s greenhouse-gas emissions. Energy-related CO2 emissions rise from 28.8 Gt in 2007 to 34.5 Gt in 2020 and 40.2 Gt in 2030. Global per-capita emissions of energy-related CO2 in 2007 was 4.4 tonnes. Higher growth of automobiles and consumption of petroleum products is invariably attended by concerns of pollution and climate changes. Global fleet of passenger light-duty vehicles (PLDVs) is estimated to increase from 770 million in 2007 to 1.4 billion in 2030. Among all sectors that emit CO2, the transport sector is the fastest growing, representing from 22% to 24% of global GHG emissions from fossil fuel sources, second only to the industrial sector. World emissions of NOx were 82 Mt in 2007, of which Road transport was responsible for about one-third of NOx emissions. Only Road transport related CO2 emission is estimated to increase from 4.8 Gt in 2007 to 6.9 Gt in 2030. The increase in CO2 emissions is largely a result of increasing demand for individual mobility in developing countries. There are strong efforts and renewed investments by manufacturers and suppliers in providing solutions to the CO2 reduction challenge. Low-carbon vehicles, such as hybrid cars, plug-in hybrids and electric cars, have received widespread public attention recently. It is estimated that share of hybrids in the global fleet will reach about 5% by 2020 and almost 8% by 2030, up from just 0.15% in 2007. Plug-in hybrids and electric cars will constitute only 0.2% of the global fleet in 2030. But increase in electricity consumption in road transport in future due to increased penetration of plug-in hybrids and electric vehicles, sees transport sector CO2 savings partially offset by power generation emissions. An estimated increase of 880 TWh of electricity consumption in transport in 2030, of which 90% occurs in PLDVs, will result in about 250 Mt of additional CO2 emissions. Authors forecasted that the use of environment-friendly and clean technologies is going to make all the difference between the winners and the losers of the industry. It is noted that current policies are insufficient to prevent a rapid increase in the concentration of greenhouse gases in the atmosphere. It is recommended that policy makers and researchers should give more emphasis on ‘cost-effectiveness as most important factor to reduce automotive GHG emission reduction’. It is also concluded that CO2 savings will be maximized if well-to-wheel impact is clearly addressed at all stages of the fuel and energy chain