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[en] A description is given of a technique and scheme developed from basic physical principles for analyzing and predicting implanted and redistributed profiles of common dopants such as boron, arsenic, phosphorus, and antimony. Basis of the scheme is a well known diffusion equation with initial conditions determined from the implant parameters. Various effects that must be considered for accurate and reliable prediction of the impurity distribution and sheet resistance variation of the implanted layers are the initial distribution, partial electrical activation and complex formation, concentration dependent, temperature dependent impurity diffusion coefficients and carrier mobilities, orientation, species dependent segregation of impurities at oxide-Si interface. The scheme in addition to including these effects considers process conditions such as temperature orientation dependent oxidation and has flexibility of handling heat treatment sequences in different ambient and at different temperatures. The numerical scheme presents the total and electrically active impurity depth distributions, sheet resistance of the layer, junction depths, and thickness of oxide grown in a form that is usable for process design optimization and sensitivity analysis. The results are in well agreement with data obtained by experimental techniques

[en] ⁵⁷Fe doped CuO, La_2-xSr_xCuO₄ and MnO₂ have been prepared by the Nitrate route. In all the three oxides the isomer shift values lie in the range 0.25-0.36 mm/s which is typical for the Fe³⁺ state. The Moessbauer parameters of iron doped CuO differ considerably from those obtained in earlier source experiments. The difference may be attributed to the aftereffects of nuclear decay. (orig.)

[en] Increasing population and urbanization results in greater production of wastewaters through industrial, commercial, domestic or agricultural activities. Discharges of these resources contain several elements including nutrients and heavy metals. Therefore, utilization of wastewater for crop irrigation alters the soil property of agricultural land by accumulating nutrients and heavy metals. Present study revealed the occurrence of elements and the existence of microorganisms in wastewater irrigated soils of two different locations adjacent to the Malir river and Lyari river. MWIS (Malir wastewater irrigated soil) and LWIS (Lyari wastewater irrigated soil) contained a greater amount of organic matter (3.13 ± 0.10 %, 3.10 ± 0.10 %) as compared to NWIS (normal water irrigated soil). Physicochemical measures such as EC (1774 ± 5.49 µS/cm), salinity (0.89 ± 0.02 %) and TDS (887 ± 5.19 ppm) and heavy metals like iron (29.02 ± 1.72 ppm), copper (0.36 ± 0.02ppm), lead (0.82 ± 0.02 ppm) and nickel (0.94 ± 0.01 ppm) were recorded higher in LWIS as compared to MWIS and NWIS. However, EC (425 ± 1.45 µS/cm) and TDS (213 ± 1.73 ppm) were found lowest in MWIS than LWIS in contrast to NWIS. Nutrients like nitrogen, potassium and heavy metal such as cadmium were approximately equal in all tested soil samples. Numerous fungal species have been sequestered from wastewater irrigated soils in which thirteen genera and twenty-seven species of fungi were isolated. Out of all fungal species, Aspergillus flavus, Curvularia intermedia, Fusarium solani and Rhizopus sp. were found dominant (6.67×103 cfu/g soil) in MWIS, while LWIS comprised the highest cfu (1 ×104 cfu/g soil) of Trichoderma viride and A. parasiticus. In addition, bacterial species like Ralstonia pickettii was found superior in MWIS with 3.24×107cfu/g soil. Whereas, five different strains of Acinetobacter lwoffii / jansani were isolated from LWIS along with Pseudomonas aeruginosa (4×105 cfu/g soil) and Shigella dysenteriae (1×105 cfu/g soil). The current study revealed the existence of microorganisms in different qualities of soils having complex nature that were irrigated by wastewater. It was evaluated that sequestered fungal and bacterial species were able to tolerate the complex nature of wastewater irrigated soils that have an adequate environment for the survival of fungi and bacteria. (author)

[en] The analysis of seismic risk has been receiving increased attention in recent years. It is recognized that seismic excitation has the potential of simultaneously damaging several redundant components in a nuclear power plant. The basis for the conclusion in the Reactor Safety (U.S. NRC 1975) that earthquakes are not major contributors to nuclear power plant risk has been questioned by several experts in the fields of seismology, earthquake engineering, and probabilistic risk analysis. Seismic risk studies performed since the Reactor Safety Study have indicated that the contribution of seismic risk to the overall plant risk may be significant. The evaluation of seismic risk requires information concerning the seismologic and geographic characteristics of the region, the capacities of structures and components to withstand earthquakes beyond design basis, and interactions between the various systems and components of a nuclear power plant. A level 1 analysis, plant damage state bridge trees, and a level 2 analysis were performed for the Krsko Nuclear Power Plant. This paper focuses on the level 2 seismic analysis since relatively few level 2 seismic analyses have been performed to date. Conceptually, the seismic level 2 study covers the same scope as the level 2 study performed for the internal events analysis. The containment performance was assessed by evaluating, for each plant damage state, the conditional probability that the damage state would result in each of the fission product release categories. Krsko has a seismic core melt frequency similar to western plants located in high seismic areas. Over half the core melt frequency is attributed to the station blackout initiating event. Approximately 66% of the seismic core damage frequency falls into the long term overpressurization with core concrete attack release category. This relatively large contribution was due to the station blackout type events resulting from a seismic initiator. Although, intact containment sequences account for only 6% of the seismic core damage frequency, most sequences lead to a very late failure. (author)

[en] Purpose: To investigate the feasibility of applying ALARA principles to current treatment planning CT scans. The study aims to quantitatively verify lower dose scans does not alter treatment planning. Method: Gammex 467 tissue characterization phantom with inserts of 14 different materials was scanned at seven different mA levels (30∼300 mA). CT numbers of different inserts were measured. Auto contouring for bone and lung in treatment planning system (Pinnacle) was used to evaluate the effect of CT number accuracy from treatment planning aspect, on the 30 and 300 mA-scanned images. A head CT scan intended for a 3D whole brain radiation treatment was evaluated. Dose calculations were performed on normal scanned images using clinical protocol (120 kVP, Smart mA, maximum 291 mA), and the images with added simulating noise mimicking a 70 mA scan. Plan parameters including isocenter, beam arrangements, block shapes, dose grid size and resolution, and prescriptions were kept the same for these two plans. The calculated monitor units (MUs) for these two plans were compared. Results: No significant degradation of CT number accuracy was found at lower dose levels from both the phantom scans, and the patient images with added noise. The CT numbers kept consistent when mA is higher than 60 mA. The auto contoured volumes for lung and cortical bone show 0.3% and 0.12% of differences between 30 mA and 300 mA respectively. The two forward plans created on regular and low dose images gave the same calculated MU, and 98.3% of points having <1% of dose difference. Conclusion: Both phantom and patient studies quantitatively verified low dose CT provides similar quality for treatment planning at 20–25% of regular scan dose. Therefore, there is the potential to optimize simulation CT scan protocol to fulfil the ALARA principle and limit unnecessary radiation exposure to non-targeted tissues.

[en] Soybean cultivars Epps (MG-V) and Williams 82 (MG-111) were planted on four dates from May to August at one month interval at Malakhandher Farm, Agricultural University Peshawar. The two yields were regressed on date of sowing to quantify the effect of date of sowing on soybean cultivars. A steady decrease in yield was observed as sowing was delayed from May 1st onward. The yield in Epps decreased at the rate of 58.6 kgha/sup -1/ day/sup -1/ from May to August and of Williams 82 decreased at the rate of 163.6 kgha/sup -1/ day/sup -1/delay in sowing. On the average Epps produced 4227 kgha/sup -1/ total dry matter yield, where as Williams 82 produced 3451 kgha/sup -1/ respectively. Both cultivars gave maximum biological and seed yields in early planting than delay planting. It can be concluded that the two soybean cultivars can be planted during May to avoid drastic reduction in yields under Peshawar valley conditions. (author)

[en] The pot experiment was carried out to evaluate the effect of tea compost on plant growth under salinity. Plants were grown in clay pots filled with sandy loam soil and irrigated by saline water (0, 50 and 100mM NaCl) with and without tea compost amendments. Soil evapotranspiration (ET), vegetative and reproductive growth and biochemical parameters were studied in this experiment. ET rate was increased with increasing salinity, whereas, it decreased with application of tea compost under all salinity. Vegetative (shoot height, number of leaves, fresh and dry biomass) and reproductive (number of seeds per plant) growth significantly decline under increasing salinity levels. Tea compost treatment helped in improving all these parameters. Total photosynthetic pigments (chlorophyll a, b, carotenoids and total chlorophyll content) showed reduction under raising salinity levels, while betterment was recorded with application of tea compost. Organic solutes (soluble sugars, proteins, free amino acids and phenolic content) increased with increasing salinity (50-100mM NaCl). Increased soluble sugars were found with tea compost treatment under non-saline control and decreased in salinity. Soluble proteins, amino acids and phenolic content increased with application of tea compost under both control and salinity. It is concluded that tea compost treatment is found to cope with salinity stress and improve plant growth and biochemical parameters by diluting the hazardous effects of salinity. (author)

[en] Fetus in fetu is a rare entity. The patient usually presents this condition in childhood. A case in which the patient presented it in adulthood, with a lump in the abdomen, is reported. Computed tomography findings were diagnostic of this condition and a prospective diagnosis could be made. Computed tomography also helped to differentiate it from mature teratoma. Copyright (2001) Blackwell Science Pty Ltd

[en] Current feeder system (CFS) of steady state superconducting tokamak 1 (SST-1) consists of ten pair of vapour cooled current leads (VCCL). Helium vapour consumption of a VCCL is an important parameter to be measured accurately during operation of current leads. To measure flow precisely and accurately, we use venturi type flow element. A venturi flow element was designed for required flow rate with accuracy of approximately +/- 1% and the same was machined, finally it was calibrated and validated to define its discharge co efficient and found to be in agreement with the designed value. These venturi flow elements with Differential pressure transmitter (DPT) have been installed in helium gas return network of current feeder system of SST-1. This paper describes design, validation and installation and commissioning of venturi flow element with its DPT. (author)