Mukesh Kumar

Natural activities of 238U, 232Th and 40K in some Indian building materials

Abstract The activity concentrations of 226 Ra , 232 Th and 40 K have been determined by gamma-ray spectrometry. The measured activity in the selected building materials ranges from (3.2 to 151.7 Bq/kg ), 14 to 63.7 Bq/kg and 24.3 to 121.5 Bq/kg for 226 Ra , 232 Th and 40 K respectively. The activity concentration of 238 U has been determined using fission track technique and the value ranges from 0.11 to 3.85 ppm . The concentrations for these natural radionuclides are compared with the reported data from other countries. Radium-equivalent activities (Raeq) are calculated for the measured samples to assess the radiation hazards arising due to the use of these materials in the construction of dwellings. All building materials have shown Raeq activities lower than the limit set in the Organization for Economic Cooperation and Development (OECD) report (370 Bq/kg ) , equivalent to external gamma dose of 1.5 mSv yr −1 . A good correlation has been observed between 238 U and 226 Ra in these materials.

Study of uranium, radium and radon exhalation rate in soil samples from some areas of Kangra district, Himachal Pradesh, India using solid-state nuclear track detectors

Abstract LR-115 plastic track detectors have been used for the measurement of radon exhalation rate and radium concentration in soil samples collected from some villages of Kangra district, Himachal Pradesh, India. Uranium concentration has also been determined in these soil samples using fission track technique. Radium concentration in soil samples has been found to vary from 11.54 to 26.71 Bq Kg −1 , whereas uranium concentration varies from 0.75 to 2.06 ppm . The radon exhalation rate in these samples has been found to vary from 15.16 to 35.11 mBq Kg −1 h −1 (502.12 to 1162.64 mBq m −2 h −1 ).

Uranium content measurement in drinking water samples using track etch technique

Abstract The concentration of uranium has been assessed in drinking water samples collected from different locations in Bathinda district, Punjab, India. The water samples are taken from hand pumps and tube wells. Uranium is determined using fission track technique. Uranium concentration in the water samples varies from 1.65±0.06 to 74.98±0.38 μg/l . These values are compared with safe limit values recommended for drinking water. Most of the water samples are found to have uranium concentration above the safe limit. Analysis of some heavy metals (Zn, Cd, Pb and Cu) in water is also done in order to see if some correlation exists between the concentration of uranium and these heavy metals. A weak positive correlation has been observed between the concentration of uranium and heavy metals of Pb, Cd and Cu.

2,4‐Dinitrophenol‐Catalyzed α‐C(sp3)−H and C(sp)−H Bond Functionalization of Cyclic Amines and Alkynes: Highly Regio‐/Diastereoselective Synthesis of α‐Alkynyl‐3‐Amino‐2‐Oxindoles

A transition-metal- and oxidant-free DNP (2,4-dinitrophenol)-catalyzed atom-economical regio- and diastereoselective synthesis of monofunctionalized α-alkynyl-3-amino-2-oxindole derivatives by C-H bond functionalization of cyclic amines and alkynes with indoline-2,3-diones has been developed. This cascade event sequentially involves the reductive amination of indoline-2,3-dione by imine formation and cross coupling between C(sp(3) )-H and C(sp)-H of the cyclic amines and alkynes. This reaction offers an efficient and attractive pathway to different types of α-alkynyl-3-amino-2-oxindole derivatives in good yields with a wide tolerance of functional groups. The salient feature of this methodology is that it completely suppresses the homocoupling of alkynes. To the best of our knowledge, this is the first example of a DNP-catalyzed metal-free direct C(sp(3) )-H and C(sp)-H bond functionalization providing biologically active α-alkynyl-3-amino-2-oxindole scaffolds.