Authors:M. Arshed, M. Siddique, M. Anwar-ul-Islam, N. Hussain, K. Shahid, and N. Butt
The Mössbauer technique has been used to study the oxidation of alloy 1.4306S (SS-304L) at 1200°C exposed in atmospheres of air and steam, for, 1, 6, 24, 100 and 400 hours. By oxidation in air the major products are -FE2O3, -FE2O3, and Fe3O4 while, during oxidation in steam they are -FeOOH, -Fe2O3 and Fe3O4. A minor phase detected following both kinds of oxidation may be ascribed to MnCrFeO4, Cr2FeO4, -FeOOH and -FeOOH produced in steam only while the base material is found following air oxidation. The proportion of Fe3O4 on the scale remains constant for all exposure durations in air oxidation, while it becomes constant in steam oxidation only in cases where the entire sample has been oxidized.
Authors:S. Waheed, N. Siddique, M. Arif, I. Fatima, N. Khalid, S. Rahman, M. Daud, and M. Wasim
This paper presents the results of the proficiency test exercise conducted in Pakistan for the determination of trace elements
in mushroom reference material. Thirteen laboratories from different organizations of the country submitted trace elemental
data on Al, As, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hg, K, Li, Mg, Mn, Na, P, Pb, Rb Sc, Si, Sm, Sr, Th, Zn. Results for
Al, As, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Na, Rb Sc, and Zn, in the mushroom material were reported by two or
more participating laboratories and could be subjected to statistical evaluation. The original data of these trace elements
was subjected to a computer program “Histo Version 2.1” provided by IAEA. The four outlier tests, i.e., Dixon, Grubbs, skewness
and kurtosis were applied to the data sets. Consensus (overall) mean values, absolute standard deviation, relative standard
deviation, standard error, median and range of values for these elements have been reported at a significance level of 0.05.
Authors:M. Siddique, M. Anwar-ul-Islam, N. Butt, N. Hussain, S. Rehman, and M. Arshed
Room temperature corrosion studies have been made on the rust of commercially available mild steel in a simulated acid rain
environment using the method of transmission Mössbauer spectroscopy. The main corrosion products identified are α-FeOOH, γ-FeOOH,
and a product with unfamiliar parameters which seems to be amorphous in nature (being very large linewidth −2.5 mm/s) and
may be considered as an intermediate phase. A small amount of γ-Fe2O3 (6–8%) is also observed.
Authors:Sabiha-Javied, S. Waheed, N. Siddique, M. Tufail, M. Chaudhry, and N. Irfan
The concentration of 32 elements was determined in phosphate rock samples from the Hazara phosphate deposits of Pakistan using
instrumental neutron activation analysis (INAA) technique employing different irradiation protocols. These included 23 major,
minor and trace elements (Al, As, Ba, Br, Co, Cr, Cs, Fe, Ga, Hf, K, Mn, Na, Rb, Sb, Sc, Sn, Ta, Th, U, V, Zn and Zr) and
9 rare earth elements (REEs) namely Ce, Eu, Ho, La, Lu, Nd, Sm, Tb and Yb. The results have been compared with the global
values of these elements. The concentrations for most of the elements studied are lower than the concentrations reported in
the literature whereas the concentrations of As, Co, Fe, K, Mn, Na and Sb are comparable. Two samples namely HR-4 and HR-5
have the highest concentrations for majority of the REFs with high enrichment factors. The quality assurance of data was performed
through the concurrent use of Lake Sediment (SL-1) and GSJ-JR-1 (Rhyolite) reference materials. The acquired data will serve
as a reference for the follow-up studies to assess the agronomic effectiveness of the Hazara phosphate rocks.
Authors:S. Waheed, N. Siddique, A. Rahman, S. Saeed, J. Zaidi, and S. Ahmad
Instrumental neutron activation analysis (INAA) and electro-thermal atomic absorption spectrometry (ETAAS) were employed to determine the toxic elements in fourteen fruits harvested in Pakistan. As, Br, Hg, Sb and Se were determined using INAA. Cadmium and Pb were determined using ETAAS. The intake levels of all toxic elements have been calculated. The data show that dates supply the maximum amount of most of the toxic elements. Peels of apple and pear have also been investigated and were found to contain higher concentration of toxic elements than their edible parts. The reliability of the techniques has been established by the use of standard reference materials. This study shows that all investigated fruits cultivated and consumed in Pakistan are safe for human consumption.
Authors:M. Siddique, N. Butt, M. Shafi, T. Abbas, and -ul-Islam Misbah
Mössbauer measurements have been carried out on Ni-substituted Mn-ferrites, Mn1-xNixFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0), at room temperature. The cation distribution at tetrahedral (A) and octahedral (B) sites and its effect on Mössbauer parameters is studied. Mn2+ ions are found to occupy sites A and B both, while Ni2+ ions occupy site B only. It has been observed that the internal magnetic fields (Heff) for all B sites increase and it remains almost constant for site A with increasing Ni concentration. The line widths of the most of B sites are decreased and no significant change is observed in isomer shift with increasing Ni concentration.