Fabrication of Nanoparticle-Doped Polyvinyl Alcohol-Cellulose Acetate Membrane and Characterization of the Surface Enhancement

In the present study, nanocomposite polymeric membranes are fabricated using polyvinyl alcohol (PVA), cellulose acetate (CA) as polymers, and dimethyl sulfoxide (DMSO) as the solvent. To enhance the performance of the membrane, nanoparticles like TiO₂, CaO, CdO, and ZrO are added to the polymeric solution and the doped polymeric solution is cast on a glass plate. Nine combinations of membranes are fabricated with two different concentrations (0.1% and 0.2%) of nanoparticles. The basic properties of the membranes such as density, porosity, viscosity, permeability, pure water flux, and water content are studied for the samples. Membrane pore structure and surface properties are identified and it is found that doping nanoparticles on the surface of membranes improve mechanical strength, stability, pore size, etc., allowing the membranes to perform better in extreme industrial-level effluent treatment applications. High-resolution scanning electron microscopy (SEM) shows the homogeneous dispersion of ZrO, TiO₂, CaO, and CdO nanoparticles on the surface of the PVA-CA membrane. The doping of nanoparticles on the PVA-CA membrane results in improved mechanical strength and good chemical oxidation stability. In comparison, the PCD-TiO₂ sample shows high thermal stability and oxidation stability at high temperatures until 200°C, which has a high potential for treating industrial effluents.     

Microwave D-InSAR technique for assessment of land subsidence in Kolkata city,India

An effective microwave Differential Interferometric Synthetic Aperture Radar (D-InSAR) technique was used to rapidly assess the potential land subsidence with high precision by exploiting the phase difference of two temporally separated SAR data in the region of Kolkata city, India. The objective of this study is to assess land subsidence using D-InSAR technique and to delineate the regions of land subsidence caused by over exploitation of groundwater by minimising the errors by applying topographic and atmospheric corrections. The study area forms a part of Indo-Gangetic plain. Three ENVISAT Advanced Synthetic Aperture Radar ?(ASAR) images of the years 2003, 2007 and 2010 were acquired to study the temporal evolution of land subsidence in the study area. The phase changes due to topography in the interferograms were removed by using Shuttle Radar Topography Mission (SRTM) degital elevation model data. Medium Spectral Resolution Imaging Spectrometer (MERIS) data were applied to remove the atmospheric noise in the interferogram. The deformation fringes were observed in the northern and central part of the study area where the land subsidence was 12 and 18 mm during the years of 2003–2007 and 2007–2010. The regional variation in the piezometric head compares well with the fringes of the interferogram. This confirms over extraction of groundwater is the main cause for land subsidence in this region. Hence, it is necessary to reduce groundwater pumping and to augment rainfall recharge in northern part of the study area.     

Brazilian Solar Spectroscope (bss)

Digital, decimetric (200–2500 MHz) Brazilian Solar Spectroscope (BSS) with high time (10–1000 ms) and frequency (1–10 MHz) resolution is in regular operation since April, 1998, at National Space Research Institute (INPE) at São José dos Campos, Brazil. BSS operates in conjunction with a 9-m diameter polar mounted antenna. It allows to select suitable observing frequency range, frequency and time resolutions and data can be digitized up to 100 channels. BSS has capabilities of quasi-real time display of the ongoing dynamic spectra of the solar activity that enables the observer to modify observational parameters so as to suit a specific type of activity such as spikes and improve the quality of data acquisition and storage. Minimum detectable flux density of the spectroscope, for different combinations of the observational parameters, is 3 s.f.u. Observations are carried out routinely from 11 UT to 19 UT. Necessary software for data acquisition and reductions has been developed in IDL 5.3 environment. Data are available in FITS and ASCII formats. Absolute timing accuracy of the station is less than 3 ms. Here, we present examples of the bursts which have been recorded by BSS and available display facilities.     

Reduction in the testosterone levels by PCBs and DDE in Dall''s porpoises of northwestern North Pacific

The increasing residue levels of PCBs and DDE in the blubber of dalli-type Dall's porpoises were found to have a negative effect on the testosterone levels in blood. Decrease in the levels of testosterone was statistically significant with increase in DDE concentrations. The results obtained suggest that the present levels of environmental contamination by persistent organochlorines can cause an imbalance of sex hormones and subsequent reproductive abnormalities in wild. The other hormone measured, aldosterone, which has no sexual function, was independent of the effects of both PCBs and DDE.     

Quasi-Periodicity in global solar radio flux at metric wavelengths during Noise Storms

We present observational results from studying the quasi-periodicities in global solar radio flux during periods of enhanced noise storm activity, over durations of 4 hr a day (`intra-day' variations), observed at 77.5 MHz with the newly commissioned log-periodic array tracking system at the Gauribidanur Radio Observatory. Positional information on the storm centers was obtained with the radio imaging data from the Nan\c cay Radio Heliograph (NRH), while their active region counterparts on the photosphere (and the overlying chromosphere ) were located from the H images of the Big Bear Solar Observatory. The quasi-periodicity in flux was found to be 110 min, with the fluctuation in flux being 3(±1.5) solar flux units (s.f.u.). The results of such pulsations are interpreted qualitatively as evidence for coronal seismology.     

The MJO and global warming: a study in CCSM4

The change in Madden–Julian oscillation (MJO) amplitude and variance in response to anthropogenic climate change is assessed in the 1° nominal resolution community climate system model, version 4 (CCSM4), which has a reasonable representation of the MJO characteristics both dynamically and statistically. The twentieth century CCSM4 run is compared with the warmest twenty-first century projection (representative concentration pathway 8.5, or RCP8.5). The last 20 years of each simulation are compared in their MJO characteristics, including spatial variance distributions of winds, precipitation and outgoing longwave radiation, histograms of event amplitude, phase and duration, and composite maps of phases. The RCP8.5 run exhibits increased variance in intraseasonal precipitation, larger-amplitude MJO events, stronger MJO rainfall in the central and eastern tropical Pacific, and a greater frequency of MJO occurrence for phases corresponding to enhanced rainfall in the Indian Ocean sector. These features are consistent with the concept of an increased magnitude for the hydrological cycle under greenhouse warming conditions. Conversely, the number of active MJO days decreases and fewer weak MJO events occur in the future climate state. These results motivate further study of these changes since tropical rainfall variability plays such an important role in the region’s socio-economic well being.     

Further Constraints on Electron Acceleration in Solar Noise Storms

We reexamine the energetics of nonthermal-electron acceleration in solar noise storms. A new result is obtained for the minimum nonthermal-electron number density required to produce a Langmuir-wave population of sufficient intensity to power the noise-storm emission. We combine this constraint with the stochastic electron acceleration formalism developed by Subramanian and Becker (2005) to derive a rigorous estimate for the efficiency of the overall noise-storm emission process, beginning with nonthermal-electron acceleration and culminating in the observed radiation. We also calculate separate efficiencies for the electron acceleration–Langmuir wave generation stage and the Langmuir wave–noise-storm production stage. In addition, we obtain a new theoretical estimate for the energy density of the Langmuir waves in noise-storm continuum sources.     

Deep groundwater flow as the main pathway for chemical outputs in a small headwater watershed (Mule Hole,South India)

This study examined the water and chemical cycles of a small forested head catchment. Application of Cl^? mass balance lead to the identification of a groundwater baseflow located into the active zone of the crystalline aquifer, below the weir. These findings indicate that groundwater contributes to a large part of chemical outputs at the catchment scale. This study shows that groundwater should not be ignored in most small watershed studies because this flow path and associated solutes are strongly significant for chemical balance assessment.