Adsorption of heavy metals in mine wastewater by Mongolian natural zeolite

AbstractIn the first, Mongolian natural zeolites, whose base components were clinoptilolite, mordenite, and chabazite, were characterized in terms of element content, cation exchange capacity, and the like. Since the molar ratios of aluminum relative to silicon contained in Mongolian natural zeolites used in this study were lower than those of pure zeolites, the natural zeolite samples contained substantial amounts of impurities. The cation exchange capacity of the natural zeolite sample relatively increased with increasing aluminum content in the zeolite sample. Secondly, the batch equilibrium adsorptions of heavy metals, i.e., copper, zinc, and manganese, from model aqueous wastewater by Mongolian natural zeolites were carried. The natural zeolites could adsorb and remove the heavy metals in the aqueous solutions. The precipitation of metal hydroxide affected the results of adsorption in some cases. The saturated adsorbed amounts of the heavy metals estimated by Langmuir equation were almost same with one another, increased with solution pH and with cation exchange capacity of the natural zeolite

Numerical prediction of cavitation and pressure fluctuation around marine propeller

The applicability of numerical prediction method for cavitation around marine propeller was studied. A commercial CFD code was applied for computation of 10 different propellers. The computed cavitation patterns and pressure fluctuations were compared with model test. As the result, it s shown that this method can be used for the prediction of the behavior of sheet cavitation and the pressure fluctuation of the 1st order of blade frequency component.http://deepblue.lib.umich.edu/bitstream/2027.42/84315/1/CAV2009-final141.pd

Methods to create hazard maps for flood disasters with sediment and driftwood

As flood disasters with sediment and driftwood are becoming severe, it is required to evaluate the risk of such disasters. The present study proposes methods to create hazard maps for such type of flood disasters using a watershed model and a 2-D flood flow model, and applied the methods to the Akatani river flood disaster in 2017 to discuss their applicability and challenges. The upstream boundary conditions of 2-D flood flow model are specified for the hydrographs of flow discharge, sediment discharge and driftwood discharge by using the results obtained from their basin model. As a result of the Akatani river simulation with the proposed methods, we found that the computational results reproduce the inundation area and elevation change, and the proposed methods are effective in creating flood hazard maps with sediment and driftwood.</p

Effects of calcium channel blockers on coronary vasoconstriction induced by endothelin-1 in closed chest pigs

AbstractThe purpose of this study was to determine the effects of endothelin-1 on the coronary vascular bed of closed chest pigs. Endothelin-1 (3 to 30 pmol/kg body weight) was selectively administered into the left anterior descending coronary artery. Coronary blood flow and epicardial vessel diameter were measured by quantitative arteriography. Arterial pressure increased after a 30 pmol/kg dose and heart rate was not changed.Coronary blood flow and vessel diameter of the left anterior descending artery significantly decreased by 74% and 32%, respectively (p < 0.01 versus control) after the 30 pmol/kg dose, whereas these variables modestly decreased in the left circumflex artery. Endothelin-1 in doses of 10 to 30 pmol/kg produced electrocardiographic ST segment elevation associated with decreased oxygen saturation of coronary sinus venous blood. Endothelin-induced coronary vasoconstriction was significantly inhibited after treatment with intravenous diltiazem (0.2 mg/kg, n = 6) or nifedipine (0.1 mg/kg, n = 5), but not after vehicle administration (n = 4).This study demonstrates that intracoronary administration of endothelin-1 causes significant myocardial ischemia through coronary vasoconstriction, which is inhibited by a calcium channel blocker. The data suggest that calcium influx into the smooth muscle cells appears to be involved at least in part in the mechanism of endothelin-induced coronary vasoconstriction in vivo

Application of Entrainment Velocity Concept for Evaluation of River Morphology: A Numerical Model Study

Conventionally, fine sediment transport is evaluated in terms of advection-diffusion equation of suspended sediment in which the erosion rate of sediment from the bedload layer plays a significant role. The present study aims to evaluate the riverbed evolution and associated morphological changes in fine sediment dominated Bhairab River of Bangladesh by a depth integrated two-dimensional numerical model. The erosion rate of bed sediment has been evaluated by two approaches. The first approach applies the fall velocity of the sediment particle and equilibrium reference sediment concentration. The other employs the entrainment velocity concept. The results obtained from numerical simulations are verified by the field investigations. The results suggest that the riverbed evolution and morphological changes predicted with the entrainment velocity concept show better agreement with the data obtained from the field investigations.</p

Phase transitions of an intrinsic curvature model on dynamically triangulated spherical surfaces with point boundaries

An intrinsic curvature model is investigated using the canonical Monte Carlo simulations on dynamically triangulated spherical surfaces of size upto N=4842 with two fixed-vertices separated by the distance 2L. We found a first-order transition at finite curvature coefficient \alpha, and moreover that the order of the transition remains unchanged even when L is enlarged such that the surfaces become sufficiently oblong. This is in sharp contrast to the known results of the same model on tethered surfaces, where the transition weakens to a second-order one as L is increased. The phase transition of the model in this paper separates the smooth phase from the crumpled phase. The surfaces become string-like between two point-boundaries in the crumpled phase. On the contrary, we can see a spherical lump on the oblong surfaces in the smooth phase. The string tension was calculated and was found to have a jump at the transition point. The value of \sigma is independent of L in the smooth phase, while it increases with increasing L in the crumpled phase. This behavior of \sigma is consistent with the observed scaling relation \sigma \sim (2L/N)^\nu, where \nu\simeq 0 in the smooth phase, and \nu=0.93\pm 0.14 in the crumpled phase. We should note that a possibility of a continuous transition is not completely eliminated.Comment: 15 pages with 10 figure

Controlling Sedimentation through Regulating the River by Thalpitigala Reservoir Project

Mahaweli is the main river in Sri Lanka and it has many main multipurpose reservoirs, especially to cater power and irrigation requirement of the country. Reservoir capacity loss which is the major problems causing to the effectiveness of the major reservoirs in Sri Lanka, is mainly caused by sedimentation due to upstream erosion. Hence proper monitoring, calculating and adopting measures are very important in planning a reservoir. But due to the complex nature of factors effect on sedimentation and lack of long-term data make calculation difficult. This study discusses how different data obtained from numerical modelling and bathymetric surveys of different locations of the catchment and those are used to select and verify the empirical equation, calculation of capacity loss and make proposals to minimise sedimentation for proposed Thalpitigala Multipurpose Project in Mahaweli upper catchment. The outcomes indicate high erosion (690 m3 km−2) and sediment transportation making rapid loosing of the capacity (5.13 MCM in 15 years) of the proposed reservoir. Thus, upper catchment protection with reforestation to reduce erosion, introduction of check dams in the upstream flow to trap the transported sediment and introduction of proper removal measures of deposited sediment are discussed for the proposed reservoir project.</p