Abstract: In the marine environment, biofilms cover most of the subtidal and intertidal solid
surfaces. Culturable bacteria forming marine biofilms were isolated on artificial substrate called acrylic coupons. The bacterial isolates were identified through a comparison of 16S rDNA sequences. A total of 115 strains were cultured and identified, 45 of which showed the same sequences with other strains. Therefore, 70 strains were finally identified. The bacterial isolates belonged to a–Proteobacteria (32 isolates), g–Proteobacteria (12 isolates), CFB group bacteria (4 isolates), high GC Gram-positive bacteria (9 isolates), and low GC Gram-positive bacteria (13 isolates). The bacterial isolates may be used as standard bacteria to test new antifouling agent. They may also be utilized as useful bacteria to enhance the settlement of commercial algae and invertebrate larvae for aquaculture.
Abstract: The evaluation of similarity theory, z-less formulation of turbulence, and validation for
various stable conditions is addressed with the use of CASES99 data over grassland. The dependence of the flux-gradient relationships on height and stability parameters is evaluated. For very stable conditions, similarity relation based on Monin-Obukhov theory is locally invalid and new treatments are required. The flux intermittency is recommended as a good indicator of stability for very thin stable boundary layer.
Abstract: We have tried to develop a lithium/thionyl chloride reserve battery (560W). A cell consists of 5 double-sided cathodes and anodes (toroidal shape, electrode area: 100 cm2, cell surface area: 900 cm2, current density: 22mA/cm2). We have designed a unique internal serial connection, which is capable of obtaining a desired voltage by simply stacking the cells and then tightening the internal serial connection
volts. A piston-type electrolyte reservoir is designed. Our dual-piston electrolyte reservoir requires smaller space for the piston movement than a single-piston reservoir. It also renders reliable opening of the diaphragm, and appropriate electrolyte transferring speed to avoid damage to the carbon electrodes. The batteries underwent performance tests, environmental tests, and accelerated aging test.
Abstract: This paper presents a study related to the assessment of the radiological impact on the environment due to the operation of the Pakistan Research Reactor-1 (PARR-1) at the Pakistan Institute of Nuclear Sciences and Technology (PINSTECH), Islamabad. The parameters studied include the radioactivity releases in a gaseous form and also those originating from the liquid and solid wastes produced due to the operation of this research facility. The analysis is based on the environmental monitoring data for the last 10 years (1992-2002) and the conclusions have been
drawn for the impact of the PARR-1 operation on the occupational workers as well as the general public living in the vicinity of the reactor site. Further, on the basis of this data, yearly average doses and the cumulative doses for the expected life of PARR-1, due to different radiation sources have been estimated. The analysis indicated that the maximum yearly doses at ground level for the occupational workers as well as for the public are a fraction of the International Atomic Energy
Agency’s (IAEA) defined limiting values. It is, therefore, concluded that the impact of the PARR-1 normal operation on the environment is negligible and it can be regarded as “ safe to the public as well as the occupational workers”.
Abstract: Pyrolysis kinetics of a pine nut shell in a thermo gravimetric analyzer (TGA) and the combustion and steam gasification kinetics of a pine nut shell’s chars in a thermobalance reactor were determined. Also, the steam gasification characteristics of the pine nut shell were determined in a fluidized bed reactor. The maximum pyrolysis reaction rate is obtained at 360oC from the TGA and DTG studies. The activation energy and the pre-exponential factor of the char were determined from the Arrhenius plot based on the shrinking core model. The effects of the reaction temperature (350oC - 950oC) and the O2 partial pressure on the combustion kinetics and that of the steam partial pressure (0.4 - 0.8atm) on the gasification kinetics were determined in a thermobalance reactor. In the combustion reaction, the activation energies and the pre-exponential factors are found to be 21.7 kcal mol-1 at 61.9 s-1atm-1 and 2.36 kcal/mol at 0.0029 s-1atm-1 in the reaction control and the pore-diffusion control regimes, respectively. The reaction order is found to be 1.0 with respect to the O2 partial pressure at 750oC. In the steam gasification reaction, the activation energy and the pre-exponential factor are found to be 16.9 kcal mol-1 at 0.0076s-1atm-1 and 2.67 kcal mol-1 at 0.00036s-1atm-1 in the reaction control and
the pore-diffusion control regimes, respectively. The reaction order is found to be 0.77 with respect to the H2O partial pressure at 750oC. The effects of the gas velocity (2Umf - 4Umf), reaction temperature (700oC - 850oC), steam/carbon ratio (0.56 - 1.12) and O2/C ratio (0.16 - 0.32) on the gas composition, gas yield, cold gas efficiency and the calorific value of the product gas were determined in a fluidized bed reactor (10 cm-i.d. × 1.6m-high) with the feeding rate of the pine nut shell of 1 - 3 kg hr-1. The carbon conversion, calorific value, cold gas efficiency and the total product gas yield increased with an increasing temperature. The hydrogen concentration increases with an increasing reaction temperature and the gas velocity and steam/carbon ratio as well as the hydrogen concentration decreases with an increasing O2/C ratio in the fluidized bed reactor.
Abstract: The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA has been studied in deaerated 0.01 M sodium sulfate (Na2SO4) and sodium thiosulfate (Na2S2O3) solutions at 340°C. Pre-strained reverse U-bend (RUB) specimens are tested using a static-autoclave system. The specimens show an intergranular SCC and a higher resistance to SCC in a Na2S2O3 solution than in
a Na2SO4 solution. The results of the deposits and surface analyses by using XRD and SEM/EDS confirm the existence of the sulfides. The SCC of Alloy 600 MA is associated with the reduced sulfur species and protective oxide film properties formed on the alloy surface in the Na2SO4 and Na2S2O3 solutions.
Abstract: The effect of a tetravalent dopant, Th4+, on the oxidation of UO2 was investigated using a thermogravimetry and X-ray diffraction analysis. Th-doped UO2’s with various dopant contents were prepared and their oxidation kinetic curves were obtained from the weight gains during air-oxidation. For the first oxidation step from (U1-yThy)O2 to (U1-yThy)4O9, the oxidation kinetic curves showed the same gradient regardless of the Th content. The inhibition of the oxidation reaction occurred dominantly in the second step, from (U1-yThy)4O9 to (U1-yThy)3O8. At the plateau of the second stage, the calculated O/M values and the X-ray diffraction patterns revealed that the O/M ratio was decreased with an increase of Th content. The relationship between the mean formal charge and the composition showed that the oxidation to (U1-yThy)3O8 proceeds within a certain limit. The lattice parameter of the initial material seems to affect the oxidation rate of the first step. And the oxidation reaction stopped when the average formal charge of the U atoms reached a value of 5.3.
Abstract: An immunomodulator ginsan, polysaccharide isolated from Panax ginseng, showed a
mitogenic activity, generation of LAK cells, and the secretion of several cytokines. In the present study, we evaluated the protective effects of in vivo injected ginsan against irradiation. Ginsan was found to significantly increase the number of bone marrow cells, spleen cells and the number of circulating neutrophils, lymphocytes and platelets in irradiated mice. In addition, ginsan induced the production of a variety of cytokines such as IL-1, IL-6, IL-12, TNF-a and SCF, which are required
for a hematopoietic recovery and are closely correlated with the antioxidant defense systems. We demonstrated that the pretreatment with ginsan protected the mice from the lethal effects of ionizing radiation more effectively than given after the irradiation. A dramatic increase of the survival of the ginsan-treated group from LD50/30 7.54 Gy of the PBS-control group to 10.93 Gy was observed. Moreover, the levels of the antioxidant enzymes such as superoxide dismutase (SOD), catalase and gluthathion peroxidase (GPx) were increased 1.5-2 fold in the ginsan treated mice compared to the irradiated mice. In conclusion, our data suggests that the radioprotective action of ginsan in the irradiated mice may be due to not only to the rapid regeneration of hematopoietic cells but also to the modulation of antioxidant defense systems.
Abstract: The development of electricity technology from the environmental aspect has become the key factor for competitiveness, i.e., environmental friendliness is one of the most important considerations for technology development. Under the monopolised electric industry of the past, there was little motivation for individual companies to actually manage their company. However, because of the increasing demand for energy and the concerns for the environment, energy policies are shifting towards a sustainable development, which considers both the economics and
environmental protection. According to the paradigm shift of the energy policy, it is necessary to compare two major electricity sources from the view of environmental management issues. It is effective with the common dimensionless unit concerning the various environmental categories including the radiological and non-radiological points of view, which can be realized by the new environmental impact assessment methodology such as the Life Cycle Assessment (LCA). This study aims at a comparison of the environmental impacts of the nuclear and coal power generation
systems using the LCA methodology. These results are very preliminary ones, however, this study will be helpful in making a decision on a long term electricity plan and the energy mix optimization when considering the environmental aspect in Korea and also the power generation companies could enhance their images by showing off their willingness to improve the environmental quality.