Azhar Rashid

Uptake of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) by river water fish: The case of River Chenab

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in eleven edible fish species (5 herbivorous and 6 carnivorous) collected from the River Chenab, Pakistan, during 2007-2009. Total OCP and PCB concentrations (ng g(-1) wet weight, ww) ranged between 13-107 (mean: 38) and 3.1-93.7 (mean: 20) for five herbivorous fish species and 21.6-365 (mean: 148) and 2.5-108 (mean: 30) for six carnivorous species, respectively. The trends of detected organochlorine pesticides (OCPs) in fish samples were: DDTs>PCBs>chlordanes>HCHs. The mean concentration(s) (ng g(-1) ww) of OCPs were relatively higher in all fish species collected near industrial areas followed by urban and agricultural areas. Risk assessment of OCPs and PCBs indicated that fish intake may pose health risk to humans with a consumption rate of >8 g/person/day. The hazardous ratios for the 50th and 95th percentile data of OCPs and PCBs in fish exceeded the value of 1, suggesting that the daily exposure to OCPs and PCBs yield a lifetime cancer risk greater than 1 in 10,000.

Efficient design of integrated antennas on Si for on-chip wireless interconnects in multi-layer metal process

In this study it has been shown that the transmission gain of an integrated dipole antenna on a Si chip used for an on-chip wireless interconnect is drastically reduced in a multi-layer metal interconnect scheme when a second metal layer is placed above the antenna at the usual interlayer metal distance. The best way to preserve high gain of the integrated antenna in such a multi-layer metal process is to design an antenna with excitation vertically through the Si substrate. In the presence of the upper metal layers, the vertically excited field mode propagating through the Si substrate does not cause any significant reduction in the power transmission of the antenna. Simulations of the structures have been carried out using the ANSOFT high frequency structure simulation (HFSS) program employing the three dimensional finite element method. A simple analytical model has also been developed, and the results are presented for comparison.

Bioremediation Potential of White Rot Fungi, Pleurotus Spp against Organochlorines

White rot fungi play significant role in biological dissipation of Organochlorine (DDT, HCH, Aldrin, Dieldrin, Endrin, Endosulfan and Heptachlor) in ecosystem. Relative biodegradation potential of Pleurotus ostreatus(OST-1), Pleurotus pulmonarious (Sajor- Caju)(WC-537),Pleurotus ostreatus( WC-522), A-6 and R-22 (Pleurotus ostreatus) against above pesticides were studied by using GC-ECD. HCH was degraded 84% by OST-1 which is a local strain, followed by A-6 (55%), WC-522 (45%), OST-Belgium (29%) and WC-537 (4%) which are exotic strains of Pleurotus. Maximum Degradation of 4,4-DDT and 2,4-DDT was done by OST-1(67% and 65%)respectively. Influence of A-6 (69%), OST-Belgium (69%) and WC-537 (51%) was more pronounced for 4,4-DDT than for 2,4-DDT with only 14%, 16% and 0% respectively. Exotic strain of P. ostreatus (WC-522) was the most inefficient of the isolates and produced only 3% reduction in 2,4-DDT and no reduction was observed in case of 4,4-DDT. In the study only A-6 and OST-1 were found to produce some reduction while OST-Belgium, WC-522 and WC-537 did not produce any amount of reduction in aldrin and dieldrin quantities. Efficacy of isolates varied significantly with each other for a-endosulfan and b-endosulfan A-6 and OST-1 were found most efficient and at par with each other in reducing the amount of α-and β-endsulfan in bioassay. Mean maximum reduction of Endrin 32% was recorded in WC-537 followed by 29% in WC-522 and 14% in OST-Belgium. Isolates also vary greatly in degradation of heptachlor. Based on results it is highly recommended to use local Pleurotus isolates of Particular area where bioremediation need to be done.