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Reverse osmosis is being increasingly used for desalination of seawater, brackish water and as well the marginal and polluted wastewaters.The operation of waters bearing substantial amount of silica is only feasible if there is a ...
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Reverse osmosis is being increasingly used for desalination of seawater, brackish water and as well the marginal and polluted wastewaters.The operation of waters bearing substantial amount of silica is only feasible if there is a chemical pretreatment in process to prevent excessive and unbearable fouling by this refractory deposit. In this study, model solutions representing tailings wastewater which usually has high silica content was used in standard jar tests using the Boltac Coagulation and Flocculation simulator to determine the effectiveness of chemical pretreatment (by precipitation and coagulation) for removal of silica and other species such as magnesium, calcium, iron and manganese which affect silica fouling. Two precipitants were tested: lime and soda ash, and caustic soda. Precipitant aids (alum and ferric chloride) were also examined in combination with optimum precipitant doses to observe their differential effects. The optimum precipitant dose of caustic sods was 200 mg/L. Ferric chloride and alum were tested with this optimum caustic soda dose, but did not improve removal significantly, if at all. The optimum precipitant dose of lime and soda ash was 150 mg/L lime and 450 mg/L soda ash. Ferric chloride and alum were tested with this optimum lime and soda dose, but again did not improve removal enough to warrant their use. Neither of the methods were as effective in removal of magnesium and calcium as in removal of other components; lime and soda ash treatment as expected actually increased the calcium content of solutions.
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Oxidative stress is considered a major contributor to the etiology of both "normal" senescence and severe pathologies with serious public health implications. Several cellular sources, including mitochondria, are known to produce ...
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Oxidative stress is considered a major contributor to the etiology of both "normal" senescence and severe pathologies with serious public health implications. Several cellular sources, including mitochondria, are known to produce significant amounts of reactive oxygen species (ROS) that may contribute to intracellular oxidative stress. Mitochondria possess at least 10 known sites that are capable of generating ROS, but they also feature a sophisticated multilayered ROS defense system that is much less studied. This review summarizes the current knowledge about major components involved in mitochondrial ROS metabolism and factors that regulate ROS generation and removal at the level of mitochondria. An integrative systemic approach is applied to analysis of mitochondrial ROS metabolism, which is "dissected" into ROS generation, ROS emission, and ROS scavenging. The in vitro ROS-producing capacity of several mitochondrial sites is compared in the metabolic context and the role of mitochondria in ROS-dependent intracellular signaling is discussed.
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This paper summarises our investigations on the conceptual studies of the Reverse Osmosis (RO) process with preheating of the feed-water,which is expected to lead to lower specific power consumption and higher water production,thu...
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This paper summarises our investigations on the conceptual studies of the Reverse Osmosis (RO) process with preheating of the feed-water,which is expected to lead to lower specific power consumption and higher water production,thus further reducing the cost of desalination by this advanced RO process. There are,however,no adequate calculation methods to take into account the effect of temperature on the RO system performance parameters such as the recovery ratio,feed pressure,feed flow and the permeate salinity. The work presented here tries to fulfil this need through the elaboration of mathematical correlations expressing the variation of these parameters as functions of the input parameters such as feed temperature,feed salinity,and the desired production capacity. The principle of the method used is to first dimension the RO system with the help of the software ROSA and the membrane SW30 HR380 for a series of calculations (504 cases) giving the variation of the above performance parameters for a large range of the input conditions. Numerical methods were then used to obtain the correlations giving the complete variation of the performance parameters as functions of the input parameters. The correlations were then integrated into the desalination cost evaluation code,DEEP,developed by IAEA and in the course of continued development at CEA. The revised version of the code was then applied to a specific project of nuclear desalination (the TUNDE-SAL project),currently being carried out in the context of a collaboration agreement between France and Tunisia,under the aegis of the IAEA regional cooperation programme.
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Reactive oxygen species (ROS) play a key signaling role in plant and animal cells. Among the many cellular mechanisms used to generate and transduce ROS signals, ROS-induced ROS release (RIRR) is emerging as an important pathway i...
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Reactive oxygen species (ROS) play a key signaling role in plant and animal cells. Among the many cellular mechanisms used to generate and transduce ROS signals, ROS-induced ROS release (RIRR) is emerging as an important pathway involved in different human pathologies and plant responses to environmental stress. RIRR is a process in which one cellular compartment or organelle generates or releases ROS, triggering the enhanced production or release of ROS by another compartment or organelle. It was initially described in animal cells and proposed to mediate mitochondria-to-mitochondria communication, but later expanded to include communication between mitochondria and plasma membrane-localized NADPH oxidases. In plants a process of RIRR was demonstrated to mediate long distance rapid systemic signaling in response to biotic and abiotic stress. This process is thought to involve the enhanced production of ROS by one cell that triggers the enhanced production of ROS by a neighboring cell in a process that propagates the enhanced “ROS production state” all the way from one part of the plant to another. In contrast to the intracellular nature of the RIRR process of animal cells, the plant RIRR process is therefore primarily studied at the cell-to-cell communication level. Studies on intracellular (organelle-to-organelle, or organelle-to-NADPH oxidase) RIRR pathways are very scarce in plants, whereas studies on cell-to-cell RIRR are very scarce in animals. Here we will attempt to highlight what is known in both systems and what each system can learn from the other.
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Due to its convenience for integrating land and marine transportation roll on/roll off (Ro-Ro) ships are very important for offering smooth and flexible services required by the modern world of trade. Ro-Ro ships are able to load ...
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Due to its convenience for integrating land and marine transportation roll on/roll off (Ro-Ro) ships are very important for offering smooth and flexible services required by the modern world of trade. Ro-Ro ships are able to load trucks or trailer directly via their ramps, thus no lifting equipment is necessary. A lot of seaports are equipped with necessary ramps to facilitate Ro-Ro ships. On the other hand, literature related to Ro-Ro terminal operations is scarce. Thus, this study aims to develop a simulation model for Ro-Ro terminal operations in order to provide a means for better decision making and resource allocation. The model is tested by using the data from a Ro-Ro terminal in Turkey. As a result, it was discovered that the maximum utilisation rate of one of the waiting areas exceeded its capacity, which shows that the model could be a useful tool in order to identify possible bottlenecks for the Ro-Ro terminal operations.
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Reverse Osmosis (RO) process is a water purification technology which purifies drinking water, desalinate the seawater and treatment of effluents from various domestic and industries to yield potable water in the form of permeate ...
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Reverse Osmosis (RO) process is a water purification technology which purifies drinking water, desalinate the seawater and treatment of effluents from various domestic and industries to yield potable water in the form of permeate and waste in the form of RO reject or retentate or concentrate. RO reject however cannot be further purified due to the presence of high concentration of organic pollutants and high osmotic pressure must be treated before discharging. This paper review about the treatment of RO reject from the effluent of textile, pharmaceutical and leather industry to reduce the environmental impacts on further disposal of RO concentrate.
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