High energy storage capabilities of CaCu3Ti4O12 for paper-based zinc-air battery.

Zinc-air batteries proffer high energy density and cyclic stability at low costs but lack disadvantages like sluggish reactions at the cathode and the formation of by-products at the cathode. To resolve these issues, a new perovskite material, CaCu3Ti4O12 (CCTO), is proposed as an efficacious electrocatalyst for oxygen evolution/reduction reactions to develop zinc-air batteries (ZAB). Synthesis of this material adopted an effective oxalate route, which led to the purity in the electrocatalyst composition. The CCTO material is a proven potential candidate for energy applications because of its high dielectric permittivity (ε) and occupies an improved ORR-OER activity with better onset potential, current density, and stability. The Tafel value for CCTO was obtained out to be 80 mV dec-1. The CCTO perovskite was also evaluated for the zinc-air battery as an air electrode, corresponding to the high specific capacitance of 801 mAh g-1 with the greater cyclic efficiency and minimum variations in both charge/discharge processes. The highest power density (Pmax) measured was 127 mW cm-2. Also, the CCTO based paper battery shows an excellent performance achieving a specific capacity of 614 mAh g-1. The obtained results promise CCTO as a potential and cheap electrocatalyst for energy applications.

Efficient Solar Energy Conversion Using CaCu3Ti4O12 Photoanode for Photocatalysis and Photoelectrocatalysis.

A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm(2), indicating the visible light induced photocatalytic ability of CCTO. Visible light mediated photocatalytic and photoelectrocatalytic degradation efficiency of CaCu3Ti4O12 pellets (CCTO) was investigated for three classes of pharmaceutical waste: erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid). It is found that the degradation process follows first order kinetic reaction in electrocatalysis, photocatalysis and photoelectrocatalysis and high kinetic rate constant was observed in photoelectrocatalysis. This was quite high in comparison to previously reported methods.

Study of the distribution of ²²6Ra in ground water near the uranium industry of Jharkhand, India.

Ground water is the principal source of drinking water in the rural areas of India. With the aim of determining, the contribution of (226)Ra to natural background radiation through drinking water exposure pathway near an operating uranium mining industry at Jaduguda, Jharkhand state of eastern India, the (226)Ra activity concentrations were measured in potable ground water. The water analysed, both tube well and well water, was collected in areas near the uranium industry and away. The (226)Ra concentration was measured by emanometric technique. The (226)Ra level in ground water was ranging between minimum detection limit of 3.5 mBq l(-1) and a maximum of 208 mBq l(-1). The analysis of variance reveals that there is insignificant statistical variation in the median (226)Ra concentration up to a distance of >10 km from the mining complex. Variation in concentration of (226)Ra in sources is attributed to the local geochemistry and environmental factors. The (226)Ra concentration was significantly elevated in natural artesian wells in the vicinity of uranium mineralised hill and it varies from 53.4 to 754 mBq l(-1). The WHO [Guidelines for Drinking Water Quality. Third Edition, Vol. 1, Recommendation (2004)] guideline value of 1000 mBq l(-1) has not been exceeded in any of the sources investigated.

Silibinin-induced apoptosis in MCF7 and T47D human breast carcinoma cells involves caspase-8 activation and mitochondrial pathway.

Silibinin, a natural flavonoid, under phase I/II clinical trial in prostate cancer patients was aimed to evaluate its chemotherapeutic potential in human breast cancer cell MCF7 and T47D. Results showed that T47D cells were found to be more sensitive to silibinin than MCF7 as observed by proliferation, clonogenic, and apoptotic assays, which was abrogated by pan-caspase inhibitor but remained unaffected by p53 inhibitor. Apoptotic events in both cell types differ temporally and also by magnitude that involved mitochondrial and caspase-8 activation pathway. These results have relevance in understanding silibinin treatment to breast tumor.

Radiation dose to members of public residing around uranium mining complex, Jaduguda, Jharkhand, India.

Uranium mining activities in the Jaduguda region of Jharkhand state, India have been carried out for the last five decades. Radioactive releases from mines, ore processing facility and tailings pond may increase the natural radiation dose to members of the public residing around the complex. It is, therefore, imperative to investigate the radiological condition around the uranium mining complex and assess the dose received by them. In the present study, it was estimated that the average radiation dose from all exposure pathways to the public living in villages around the mining complex is 2.5 mSv y(-1) and around 50 % contributed due to inhalation of radon and its progeny. The external radiation dose due to terrestrial and cosmic activity is estimated to be 1.1 mSv y(-1), which is 40 % of the total dose and ingestion dose contributes only 3% to the total dose.

Wire-mesh capped deposition sensors: novel passive tool for coarse fraction flux estimation of radon thoron progeny in indoor environments.

Deposition-based (222)Rn and (220)Rn progeny sensors act as unique, passive tools for determining the long time-averaged progeny deposition fluxes in the environment. The use of these deposition sensors as progeny concentration monitors was demonstrated in typical indoor environments as conceptually superior alternatives to gas-based indirect monitoring methods. In the present work, the dependency of these deposition monitors on various environmental parameters is minimized by capping the deposition sensor with a suitable wire mesh. These wire-mesh capped deposition sensors measure the coarse fraction deposition flux, which is less dependent on the change in environmental parameters like ventilation rate and turbulence. The calibration of these wire-mesh capped coarse fraction progeny sensors was carried out by laboratory controlled experiments. These sensors were deployed both in indoor and in occupational environments having widely different ventilation rates. The obtained coarse fraction deposition velocities were fairly constant in these environments, which further confirmed that the signal on the wire-mesh capped sensors show the least dependency on the change in environmental parameters. This technique has the potential to serve as a passive particle sizer in the general context of nanoparticles using progeny species as surrogates. On the whole, there exists a strong case for developing a passive system that responds only to coarse fraction for providing alternative tools for dosimetry and environmental fine particle research.

Radiation-induced micronucleus formation and DNA damage in human lymphocytes and their prevention by antioxidant thiols.

Thiol family of antioxidants has been considered to be the most effective class of radio protective agents. Present study reports a comparative evaluation of antioxidant thiols, namely N-acetyl cysteine (NAC), glutathione (GSH) and thioproline (TP), on gamma radiation-induced damage to human lymphocytes DNA as assessed by micronucleus (MN) formation and comet assay parameters. Pretreatment of cells with NAC, GSH and TP showed significant protection against DNA damage and MN frequency in irradiated lymphocytes (2-4 Gy). The magnitude of DNA damage protection was found to be concentration dependent (100-300 microM) which followed the order GSH>NAC>TP. Further, antioxidant thiols mediated protection against DNA damage in irradiated lymphocyte showed significant correlation with their ability to decrease intracellular ROS but not to the increase in intracellular GSH. Experiments on the effect of antioxidant thiols on plasmid DNA irradiated under cell free aqueous conditions showed that NAC exerts greater protection than GSH against radiation damage. TP showed similar responses in cellular and plasmid DNA. Greater protection of plasmid DNA by NAC is ascribable to its more potential hydrogen donor ability as revealed by radical chromogen 2,2-diphenyl-1-picrylhydrazyl (DPPH) photometric assay. Thus, present study indicated that radioprotection of lymphocytes DNA by antioxidant thiols are closely correlated to the reduction of cellular oxidative stress, which seems to involve multiple mechanisms.

Maximum likelihood estimates of mean and variance of occupation radiation doses subjected to minimum detection levels.

Data collection and its analysis in the field of nuclear safety is an important task in the sense that it powers the improvement of safety as well as reliability of the plant. Thus, occupational exposure data analysis is presented to measure the safety or reliability of radiation protection of a given facility. It also is required as a basic input in making decisions on radiation protection regulations and recommendations. A common practice in radiation protection is to record a zero for observation below minimum detection limit (MDL) doses, which leads to an underestimation of true doses and overestimation of the dose-response relationship. Exposure data (both external and internal) are collected by monitoring each individual and this kind of monitoring generally is graded as low-level monitoring. So, in such low-level monitoring, the occurrence of exposure below MDL invites statistical complications for estimating mean and variance because the data are generally censored, i.e observations below MDL are marked. In Type I censoring, the point of censoring (e.g. the detection limit) is 'fixed' a priori for all observations and the number of the censored observations varies. In Type II censoring, the number of censored observations is fixed a priori, and the point of censoring vary. The methodology generally followed in estimating mean and variance with these censored data was the replacement of missing dose by half the MDL. In this paper, authors have used the maximum likelihood estimation (MLE) approach for the estimation of mean and standard deviation. A computer code BDLCENSOR has been developed in which all these MLE-based advanced algorithms are implemented. In addition to the MLE-based method, an expectation maximisation algorithm has also been implemented. The code is written using Visual BASIC 6.0. The paper describes the details of the algorithms adopted for handling such censored data to estimate bias free mean and standard deviation.

A non-parametric statistical analysis in the measurement of outdoor gamma exposure to the residents around Trombay.

During this study, non-parametric statistical methods were used to validate the measured gamma dose rate with the calculated one, around Trombay. Portable dose rate digital gamma spectrometry system (target fieldSPEC) was used for in situ measurement of external gamma (gamma) dose rate (measured) with the range of 1 nSv/h-10 Sv/h. The activity concentration of U-238, Th-232, K-40 and Cs-137 in the soil and their respective external dose-conversion factor (nSv/h/Bq/kg) was used to evaluate the gamma dose rate (calculated). Non-parametric statistical tool like Box- and -Whisker Plot, Spearman's (rho) rank Correlation coefficient, the Wilcoxon/Mann-Whitney test and chi(2) distribution test have been applied for validation. The randomness or discrete behaviour of measured and calculated dose rate was obvious from the Box- and -Whisker Plot as mean and median of the two are not equal. The inter quartile range (Q3-Q1), which explains about the dispersion of measured and calculated dose rate were also evaluated and found to be 10 and 16 microSv/y, respectively. The linear association between the order of ranks of the two dose rates was established by using Spearman's (rho) rank correlation that showed a coefficient of R = +0.90 with the intercept +1.9, whereas Pearson's correlation was observed with a coefficient of R = +0.93 with the intercept -25.6. Wilcoxon/Mann-Whitney test shows that, medians of the calculated and the measured dose rate as significantly different under the assumption of null hypothesis and measured dose rate was made to the normal distribution by applying Z-statistics. Value of chi(2) was calculated and found to be 284.95, which was very much greater than the critical value of chi(2)(0.05) = 43.77 at a degree of freedom 30, concluding that there is a highly significant difference between the measured and calculated dose rate at 5% significance level.

Analysis of groundwater quality using fuzzy synthetic evaluation.

This paper reports the application of fuzzy set theory for decision-making in the assessment of physico-chemical quality of groundwater for drinking purposes. Methodology based on fuzzy set theory used to express the quality of water in the imprecise environment of monitored data and prescribed limits given in a non-probabilistic sense. Fuzzy synthetic evaluation model gives the certainty levels for the acceptability of the water based on the prescribed limit of various regulatory bodies quality class and perception of the experts from the field of drinking water quality. Application of fuzzy rule based optimization model is illustrated with 42 groundwater samples collected from the 15 villages of Ateli block of southern Haryana, India. These samples were analysed for 16 different physico-chemical water quality parameters. Ten parameters were used for the quality assessment using this approach. The analysis showed that four samples were in "desirable" category with certainty level of 35-58%, 23 samples were in "acceptable" category whose certainty level ranged from 37 to 75% and remaining 15 samples were in "not acceptable" category for drinking purposes with certainty levels from 44 to 100%. This concludes that about 64% water sources were either in "desirable" or "acceptable" category for drinking purposes.