M. Izquierdo

Antigenicity and Immunogenicity of a Synthetic Oligosaccharide-Protein Conjugate Vaccine against Haemophilus influenzae Type b

ABSTRACT Polysaccharide-protein conjugates as vaccines have proven to be very effective in preventing Haemophilus influenzae type b infections in industrialized countries. However, cost-effective technologies need to be developed for increasing the availability of anti-H. influenzae type b vaccines in countries from the developing world. Consequently, vaccine production with partially synthetic antigens is a desirable goal for many reasons. They may be rigidly controlled for purity and effectiveness while at the same time being cheap enough that they may be made universally available. We describe here the antigenicity and immunogenicity of several H. influenzae type b synthetic oligosaccharide-protein conjugates in laboratory animals. The serum of H. influenzae type b-immunized animals recognized our synthetic H. influenzae type b antigens to the same extent as the native bacterial capsular polysaccharide. Compared to the anti-H. influenzae type b vaccine employed, these synthetic versions induced similar antibody response patterns in terms of titer, specificity, and functional capacity. The further development of synthetic vaccines will meet urgent needs in the less prosperous parts of the world and remains our major goal.

Compressors driven by thermal solar energy: entropy generated, exergy destroyed and exergetic efficiency

This work is devoted to the study of the entropy generated, the exergy destroyed and the exergetic efficiency of lithium-bromide absorption thermal compressors of single and double effect, driven by the heat supplied by a field of solar thermal collectors. Two different applications have been considered and compared: air-cooled and water-cooled units. Water-cooled compressors work with temperatures and pressures lower than air-cooled compressors considering, in both cases, the same suction temperature, equal to 5°C. While the absorption temperature in water-cooled compressors can reach 40°C, in air-cooled systems it can vary between 30°C and more than 50°C. Under these conditions, the discharge temperature (boiling temperature within the desorber) of a single effect air-cooled unit lies between 65 and 110°C, the maximum discharge pressure being around 0.12 bar. The discharge temperatures (boiling temperature within the high pressure desorber) of the double effect air-cooled thermal compressor lies between 110°C for a final absorption temperature of 30°C, and 180°C for a final absorption temperature of 50°C. Discharge pressures can reach values of 0.3 and 1.5 bar, respectively. The lithium-bromide air-cooled thermal compressors of double-effect can be viable with absorption temperatures around 50°C, when the temperature difference between the lithium-bromide solution and the outside air is about 8°C. The double effect thermal compressor generates less entropy and destroys less exergy than the single effect unit, leading to a higher exergetic efficiency. In both cases, the compression process of the cooling fluid occurs with entropy reduction.

Heat and mass transfer in LiNO3-NH3 spray absorption system

In the present work the spray absorption method is studied for the absorption of ammonia refrigerant vapour by lithium nitrate ammonia solutions. Heat and mass transfer coefficients attainable using the spray absorption method are estimated. In this study the low-pressure absorber of a double-stage absorption refrigeration system is considered. The results show that a mass transfer coefficient equal to k m = 18.6.10 -5 m/s may be attained. The heat transfer coefficient (5.8 kW/m 2 K) obtained in the heat exchanger using the spray absorption method and the lithium nitrate ammonia solution is one order of magnitude higher than those obtained using falling film absorbers. This would lead to significantly smaller heat exchanger areas in absorption chillers.

Optimization of aquaculture systems in Spain

An analysis of present heat production systems, using fossil fuel combustion, employed for sea water heating in Spanish hatcheries is given in this paper and compared to a technical solution based on the employment of a heat pump. Price per unit of produced energy is calculated for each system using liquid and gaseous fuels, and then these prices are compared to the price obtained for a heat pump. The heat pump system is also compared, from the point of view of its precision in maintaining temperatures, to the systems used at the present. A project prototype for thermal conditioning and temperature control in aquaculture rearing tanks is described. The waste heat of the return water is recovered: first, by a static recoverer and second, by a recoverer connected to the evaporator of a refrigeration unit. The system should be used in such a way that economic benefits are obtained from its two heat sources of the frigorific system in simultaneous production of warm and chilled sea water.