A lysimeter experimental study and numerical characterisation of the leaching of incinerator bottom ash waste

Incinerator bottom ash (IBA) is a residual produced from incinerating municipal solid waste. In the past, IBA presented a big waste disposal problem; however, various recycling approaches have been adopted in recent years to mitigate this problem, as well as to provide a useful alternative to using primary aggregate resources. The use of IBA as an alternative to conventional aggregates in different civil engineering construction applications helps to conserve premium grade aggregate supplies; however, when IBA is in contact with water in the field, as a consequence of precipitation events or changes in water table, elements, such as salts and heavy metals, may be released to the soil and ground water. In this work, IBA waste was mixed with limestone aggregate to produce a blend with acceptable mechanical properties and minimum environmental risks for use as road foundation. The study focused on evaluating potential environmental impacts of some constituents, including sulphate, chloride, sodium, copper, zinc and lead in IBA blends using a lysimeter as a large scale leaching tool. Moreover, a specific scenario simulating field conditions was adopted in the lysimeter to assess the potential impact of changing conditions, such as IBA content in the blend, liquid to solid ratio (L/S) and pH value, on long-term release of heavy metals and salts. Then, numerical modelling was used to predict the release of the aforementioned constituents from IBA based on initial measurement of intrinsic material properties and the kinetic desorption process concept. Experimental results showed that zinc and lead were released in very low concentrations but sodium and sulphate were in high concentrations. The control limestone only blend also demonstrated low release concentrations of constituents in comparison to IBA blends, where constituent concentrations increased with increase in IBA content. Experimental results were compared with numerical results obtained using a non-equilibrium desorption model. Good agreement was found between the two sets of data. 

Genetic susceptibility to invasive meningococcal disease: MBL2 structural polymorphisms revisited in a large case–control study and a systematic review

Invasive infection caused by Neisseria meningitidis is a worldwide public health problem. Previous reports have indicated that carriage of common ‘defective’ structural polymorphisms of the host mannose-binding lectin gene (MBL2) greatly increases an individual’s risk of developing the disease. We report the largest case–control study so far to investigate the effect of these polymorphisms in meningococcal disease (296 PCR-positive cases and 5196 population controls, all of European ancestry) and demonstrate that no change in risk is associated with the polymorphisms overall or in any age-defined subgroup. This finding contrasts with two smaller studies that reported an increase in risk. A systematic review of all studies of MBL2 polymorphisms in people of European ancestry published since 1999, including 24 693 individuals, revealed a population frequency of the combined ‘defective’MBL2 allele of 0.230 (95% confidence limits: 0.226–0.234). The past reported associations of increased risk of meningococcal disease were because of low ‘defective’ allele frequencies in their study control populations (0.13 and 0.04) that indicate systematic problems with the studies. The data from our study and all other available evidence indicate that MBL2 structural polymorphisms do not predispose children or adults to invasive meningococcal disease.

EFFECT OF ULTRASOUND ON THE KINETICS OF OXIDATION OF OCTAN-2-OL AND OTHER SECONDARY ALCOHOLS WITH SODIUM-BROMATE, MEDIATED BY RUTHENIUM TETRAOXIDE IN A BIPHASIC SYSTEM

The initial rate of oxidation of octan-2-ol and other secondary alcohols to their ketones with NaBrO3, mediated by RuO4 in an aqueous-CCl4 biphasic system, is greater with ultrasonic irradiation than by stirring alone. Under ultrasonic irradiation the initial rate of oxidation of octan-2-ol increases with increasing % duty cycle, [RuO4] and [NaBrO3]. The kinetics of alcohol oxidation appear to be closely linked with the oxidative dissolution of RuO2 to RuO4 by NaBrO3. The observed enhancement in rate with ultrasonic irradiation appear to be association, at least in part, with the increase in interfacial surface area via the formation of an emulsion of aqueous microdroplets containing NaBrO3 in the CCl4 layer containing the non-water-soluble secondary alcohol.

Genetic susceptibility to invasive meningococcal disease: MBL2 structural polymorphisms revisited in a large case-control study and a systematic review.

AbstractInvasive infection caused by Neisseria meningitidis is a worldwide public health problem. Previous reports have indicated that carriage of common 'defective' structural polymorphisms of the host mannose-binding lectin gene (MBL2) greatly increases an individual's risk of developing the disease. We report the largest case-control study so far to investigate the effect of these polymorphisms in meningococcal disease (296 PCR-positive cases and 5196 population controls, all of European ancestry) and demonstrate that no change in risk is associated with the polymorphisms overall or in any age-defined subgroup. This finding contrasts with two smaller studies that reported an increase in risk. A systematic review of all studies of MBL2 polymorphisms in people of European ancestry published since 1999, including 24 693 individuals, revealed a population frequency of the combined 'defective'MBL2 allele of 0.230 (95% confidence limits: 0.226-0.234). The past reported associations of increased risk of meningococcal disease were because of low 'defective' allele frequencies in their study control populations (0.13 and 0.04) that indicate systematic problems with the studies. The data from our study and all other available evidence indicate that MBL2 structural polymorphisms do not predispose children or adults to invasive meningococcal disease.