Search

The tannery effluent and composite municipal sewage water drained to the East Kolkata wetland (EKW), a Ramsar Site (1208), is used for agriculture and pisciculture after natural stabilization. Such composite wastewater is characterized by exceedingly high total dissolved solids, total hardness, chloride and heavy metals concentrations. These water born pollutants generate reactive oxygen species which are potentially toxic to the biological system. These reactive oxygen species are normally detoxified by some enzymes, such as superoxide dismutase (SOD) and catalase (CAT). The present study was commenced to find out the SOD and CAT activities against the oxidative stress, if any, in four macrophytes namely, Eichhornia crassipes, Pistia stratiotes, Alternanthera sessilis and Sagittarria montevidensis of contaminated ponds (Site 1 and Site 2) of EKW and an uncontaminated site (Control site). During the course of sampling the physico-chemical factors were found significantly higher in the EKW ponds compared to the control site. In the EKW sites, higher rate of evaporation during summer months caused higher elemental concentration in the premonsoon than in other seasons. This led to high activity of both SOD and CAT enzymes. In contrast, heavy rain fall in monsoon lowers the elemental concentration - mainly due to dilution effect. Present experiment indicated that in a stressed ecosystem like EKW, the wetland plants overcome the stress by altering their stress enzyme activities, hence suggesting an evidence of adaptive mechanism to thrive in a stressful environment.

We present the development and characterization of a generic, reconfigurable, low-cost (< 350$) software-defined digital receiver system (DRS) for temporal correlation measurements in atomic spin ensembles. We demonstrate the use of the DRS as a component of a high-resolution magnetometer. Digital receiver-based fast Fourier transform spectrometers (FFTSs) are generally superior in performance in terms of signal-to-noise ratio (SNR) compared with traditional swept-frequency spectrum analyzers (SFSAs). In applications where the signals being analyzed are a very narrow band in the frequency domain, recording them at high speeds over a reduced bandwidth provides flexibility to study them for longer periods. We have built the DRS on the STEMLab 125-14 FPGA platform, and it has two different modes of operation: FFT spectrometer and real-time raw voltage recording mode. We evaluate its performance by using it in atomic spin noise spectroscopy (SNS). We demonstrate that the SNR is improved by more than one order of magnitude with the FFTS compared with that of the commercial SFSA. We also highlight that with this DRS operating in the triggered data acquisition mode, one can achieve a spin noise (SN) signal with high SNR in a recording time window as low as 100 ms. We make use of this feature to perform time-resolved high-resolution magnetometry. While the receiver was initially developed for SNS experiments, it can be easily used for other atomic, molecular, and optical (AMO) physics experiments as well. [ABSTRACT FROM AUTHOR]