Vertically aligned catalysts comprised of platinum–nickel thin films on nickel nanorods (designated as Pt–Ni@Ni-NR) with varying ratios of Pt to Ni in the thin film were prepared by magnetron sputtering and evaluated for their oxygen reduction reaction (ORR) activity. A glancing angle deposition (GLAD) technique was used to fabricate the Ni nanorods (NRs) and a small angle deposition technique for growth of a thin conformal coating of Pt–Ni on the Ni-NRs. The Pt–Ni@Ni-NR structures were deposited on glassy carbon for evaluation of their ORR activity in an aqueous acidic electrolyte using the rotating disk electrode technique. The Pt–Ni@Ni-NR catalysts showed superior area-specific and mass activities for ORR compared to those of Pt–Ni alloy nanorod catalysts prepared using the GLAD technique and compared to those of conventional large-surface area Pt and Pt–Ni alloy nanoparticle catalysts.

No abstract

No abstract

The activity levels of (226)Ra, (232)Th and (40)K were determined using gamma-ray spectroscopy in different commercial brands of cement, sand and hollow concrete bricks, which were collected from the building material suppliers of Dhaka City. The activity concentrations in the samples were found to be somewhat higher than in other countries. An effort has been made to assess the radiation hazard associated with these materials by determining the gamma activity concentration index I. It was found that the value of I for all the samples was

No abstract

No abstract

No abstract

The present investigation was conducted to assess the water quality status of the river Buriganga. Water samples were collected from three selected stations in wet (June-August) and dry (November-January) seasons during the years 2017 and 2018. Temperature and Dissolved Oxygen (DO) of water varied from 22.80 to 31.40 °C and 0.22 to 2.74 mg/L, respectively. Electrical conductivity of water varied from 180 to 598 μS/cm while pH ranged from 7.61 to 8.97. This study showed that temperature, DO and Fe were higher in wet season than in the dry season, whereas pH, conductivity and phosphate were higher in dry season than in the wet season. But manganese did not vary in different seasons. It is found that the differences of water quality parameters were significant in seasons (p<0.05) except for Fe and insignificant for stations (p>0.05) except for DO. The results reveal that there were significant differences between sampling seasons (wet and dry) (p<0.05) except for temperature and manganese. A significant correlation (p<0.01) was also found among temperature and other parameters viz. DO, conductivity, pH, phosphate. According to the result obtained in the present study, it may be said that the water quality of the river Buriganga is not acceptable to declare the river-ecosystem as a sound one ecologically.