Experimental and modeling studies of mass transfer in microencapsulated cell systems

Gaining a better understanding of mass transfer problems in encapsulated cell systems and in tissue engineering requires both experimental investigations and mathematical modelling. Specific mass transfer studies are reviewed including oxygen transfer in immobilised animal cell culture systems, modelling of electrostatic polymer droplet formation, and growth of plant somatic tissue encapsulated in alginate using electrostatics. Trop J Pharm Res, June 2002; 1(1): 3-1

An assessment of population fluctuations of citrus pest woolly whitefly Aleurothrixus floccosus (Maskell, 1896) (Homoptera, Aleyrodidae) and its parasitoid Cales noacki Howard, 1907 (Hymenoptera, Aphelinidae): A case study from Northwestern Algeria

The aim of this study was to assess the effectiveness of the parasitoid Cales noacki Howard, 1907 (Hymenoptera, Aphelinidae) in the biological control of the citrus pest woolly whitefly, Aleurothrixus floccosus (Maskell,1896) in Northwestern Algeria. In particular the pest and parasitoid population fluctuations under different environmental conditions were investigated. The study was conducted by examination and sampling of whitefly adult populations on young shoots and catches as well as its parasitoid during a 12-month period by counting the parasite and infested-live larvae. Results showed remarkable variations in abundance indices and infestation rates of larvae and adults that depended on the growth flush in foliage and meteorological conditions of the region. The woolly whitefly manifested three flight periods coinciding with three growth flushes of orange sap; in autumn towards the end of September followed by mid-November with the highest average abundance of 10 individuals per branch and a third flight period in mid-May. Phases of growth flush seemed to have an effect on the temporal distribution of adults over the sampling period from July to June. Pest emergence appeared favorable at 12-20 °C as the minimum interval temperature whereas the maximum varied between 25-33 °C with humidity levels of 50 % and 75 %. As for the incidence of natural enemies on whiteflies, despite their abundance, their impact was not optimum due to the large fluctuations in number of whiteflies. Although the pest-parasitoid complex appears to be important in the orchard, the biological regulation exerted by C. noacki while effective is insufficient for the complete neutralization of citrus woolly whitefly A. floccosus. An integrated approach is needed using additional natural enemies associated with the woolly whitefly

Review Article - Experimental and modeling studies of mass transfer in microencapsulated cell systems

Gaining a better understanding of mass transfer problems in encapsulated cell systems and in tissue engineering requires both experimental investigations and mathematical modelling. Specificmass transfer studies are reviewed including oxygen transfer in immobilised animal cell culture systems, modelling of electrostatic polymer droplet formation, and growth of plant somatic tissue encapsulated in alginate using electrostatics

Renewable energy-driven desalination technologies: a comprehensive review on challenges and potential applications of integrated systems

Despite the tremendous improvements in conventional desalination technologies, its wide use is still limited due primarily to high energy requirements which are currently met with expensive fossil fuels. The use of alternative energy sources is essential to meet the growing demand for water desalination. In the last few decades a lot of effort has being directed in the use of different renewable energy (RE) sources to run desalination processes. However, the expansion of these efforts towards larger scale plants is hampered by several techno-economic challenges. Several medium-scale RE-driven desalination plants have been installed worldwide. Nevertheless, most of these plants are connected to the electrical grid to assure a continuous energy supply for stable operation. Furthermore, RE is mostly used to produce electric power which can be used to run desalination systems. This review paper focuses on an integrated approach in using RE-driven with an emphasis on solar and geothermal desalination technologies. Innovative and sustainable desalination processes which are suitable for integrated RE systems are presented. An assessment of the benefits of these technologies and their limitations are also discussed

Assessment of wind energy to power solar brackish water greenhouse desalination units: A case study from Algeria

The Algerian desert dominates large parts of the country's vast territory, and Algeria is among the countries filling most of the world's largest desert. In fact the country is over 80% desert. Even though more than 80% of the population is located in the northern Mediterranean coastal zone, most of oil and gas fields are located in the country's vast southern desert called Sahara. Furthermore, the desert region is developed into a major tourist destination. This arid zone region is characterized by a lack of potable water. However, in addition to the abundant solar energy, the region is also endowed with important wind and brackish groundwater resources with different qualities. Therefore, a brackish water greenhouse desalination unit that is powered by wind energy is a good solution for desalting groundwater for irrigation purposes in this region. Brackish water can be used to cool the greenhouse, creating the proper climate to grow valuable crops. Moreover, at the same time the fresh water that is produced in this system may be sufficient for the irrigation of crops grown inside the unit. In this study, five typical regions in the Sahara were selected and investigated. These regions were selected since they were areas of traditional agriculture. The frequency distributions of wind speed data were collected from Surface Meteorology and Solar Energy (SSE) statistics developed by NASA and evaluated for a 10-year period. The distributions were used to determine the average wind speed and the available wind power for the five locations. The results indicated that the available wind energy is a suitable resource for power production and can be used to provide the required electricity for the brackish groundwater greenhouse desalination units.Wind energy Brackish water greenhouse desalination Weibull distribution Algeria

DESALINATION Feasibility of salt production Corn inland RO desalination plant reject brine: a case study

Abstract Production and disposal ofreject brine are an integral part of an overall desalination process. For inland desalination plants, this poses a serious challenge to operators, as the option of ocean disposal ofreject brine is not available. Various disposal options such as reinjection, lined and unlined evaporation ponds and natural depressions (lake) are currently being used. An alternative approach is to further process the reject brine to extract all the salts. This has the advantages of being enviromnentally friendly and producing commercial products (i.e., salts and fresh water). A desktop prefeasibility study using data from Petroleum Development Oman (PDO), operating plants in Bahja, Rima, Nimr and Marmul, confirmed the technical feasibility of treating reject brines in simple processing routes using SAL-PROC technology. SAL-PROC is an integrated process for sequential extraction of dissolved elements from inorganic saline waters in the form of valuable chemical products in crystalline, slurry and liquid forms. The process involves multiple evaporation and/or cooling, supplemented by mineral and chemical processing. An analysis indicated that various types of salts including gypsum, sodium chloride, magnesium hydroxide, calcium chloride, calcium carbonate, and sodium sulphate can be produced from the reject brine of PDO desalination plants. These products have an approximate market value of US $895,000 annually