Instrumental neutron activation analysis has been selected for use to measure the level of 11 environmentally significant trace elements in human scalp hair of Indonesian, Canadian and Canadian-of-Indonesian-origin (INCN) population groups. Concentration ranges and geometric means are presented. Concentration ratios of each group are evaluated to find a possible relationship between the elemental concentrations of scalp hair and the environmental condition in which the donors live.
Authors:Ihsanullah, J. Akhter, A. Rauf and M. Atta
A comprehensive radiochemical procedure for the measurement of gamma/beta activity of131I has been standarized by optimizing different steps. The procedure is mainly divided into three stages, i.e., (1) concentration
of iodine using anion exchange column followed by elution; (2) extraction of iodine into CCl4 and back extraction, and (3) precipitation as AgI. The percent chemical recovery and the lower limit of detection (LLD) were
found to be 75.5±5% and 0.014 mBq/ml, respectively.
The sorption of hafnium on hydrous titanium oxide (TiO2·1.94 H2O) has been studied in detail. Maximum sorption of hafnium can be achieved from a pH 7 buffer solution containing boric acid and sodium hydroxide using 50 mg of the oxide after 30 minutes shaking. The value ofkd, the rate constant of intraparticle transport for hafnium sorption, from 0.01M hydrochloric and perchloric acid and pH 7 buffer solutions has been found to be 17 mmole·g–1·min–2. The kinetics of hafnium sorption follows Lagergren equation in 0.01M HCl solution only. The values of the overall rate constantK
=6.33·10–2 min–1 and of the rate constant for sorptionk1=6.32·10–2 min–1 and desorptionk2=2.28·10–5 min–1 have been evaluated using linear regression analysis. The value of correlation factor() is 0.9824. The influence of hafnium concentration on its sorption has been examined from 4.55·10–5 to 9.01·10–4 M from pH 7 buffer solution. The sorption data followed only the Langmuir sorption isotherm. The saturation capacity of 9.52 mmole·g–1 and of a constant related to sorption energy have been estimated to be 2917 dm3·mole–1. Among all the additional anions and cations tested only citrate ions reduce the sorption significantly. Under optimal experimental conditions selected for hafnium sorption, As(III), Sn(V), Co(II), Se(IV) and Eu(III) have shown higher sorption whereas Mn(II), Ag(I) and Sc(III) are sorbed to a lesser extent. It can be concluded that a titanium oxide bed can be used for the preconcentration and removal of hafnium and other metal ions showing higher sorption from their very dilute solutions. The oxide can also be employed for the decontamination of radioactive liquid waste and for pollution abatement studies.
Authors:M. W. Abbasi, M. Q. Khan, M. J. Zaki, S. S. Shaukat, A. Rauf, N. Ahmed, M. Azeem and M. Tariq
Bacillus thuringiensis (B.t) is well known for its biocontrol potential against a variety of insects. Nematicidal potential of ten B.t isolates was tested against root-knot nematodes (Meloidogyne javanica (Treub) Chitwood) in vitro, under greenhouse as well as in field conditions. Eggs and second stage juveniles (J2) were exposed to 5 and 25% concentrations of bacterial cell-free aqueous extracts up to 96 h. B.t isolates showed lesser degrees of nematicidal activity at 5% concentration. However, some B.t isolates (B.t-14, B.t-16 and B.t-64) greatly reduced egg hatching and increased J2. All B.t isolates revealed suppressed egg hatching and increased mortality of J2 at 25% concentration. Soil applications with most of the B.t isolates under greenhouse and field conditions significantly improved height and fresh weights of root-knot nematode parasitized okra (Abelmoschus esculentus (L.) Moench). Some isolates, including B.t-64 reduced the number of galls and egg masses. B.t-64 reduced gall formation up to 70% under greenhouse conditions. However, 29% of decrease was observed in field conditions. Similarly, B.t-64 treated plants showed a 56% decreased in eggs/egg mass in a field experiment. Population of root-knot nematodes in the rhizosphere was decreased up to 61% in the field experiment as compared to control.