Ionic Liquids Increase the Catalytic Efficiency of a Lipase (Lip1) From an Antarctic Thermophilic Bacterium

Lipases catalyze the hydrolysis and synthesis of triglycerides and their reactions are widely used in industry. The use of ionic liquids has been explored in order to improve their catalytic properties. However, the effect of these compounds on kinetic parameters of lipases has been poorly understood. A study of the kinetic parameters of Lip1, the most thermostable lipase from the supernatant of the strain ID17, a thermophilic bacterium isolated from Deception Island, Antarctica, and a member of the genus Geobacillus is presented. Kinetic parameters of Lip1 were modulated by the use of ionic liquids BmimPF6 and BmimBF4. The maximum reaction rate of Lip1 was improved in the presence of both salts. The highest effect was observed when BmimPF6 was added in the reaction mix, resulting in a higher hydrolytic activity and in a modulation of the catalytic efficiency of the enzyme. However, the catalytic efficiency did not change in the presence of BmimBF4. The increase of the reaction rates of Lip1 promoted by these ionic liquids could be related to possible changes in the Lip1 structure. This effect was measured by quenching of tryptophan fluorescence of the enzyme, when it was incubated with each liquid salt. In conclusion, the hydrolytic activity of Lip1 is modulated by the ionic liquids BmimBF4 and BmimPF6, improving the reaction rate and the catalytic efficiency of this enzyme when BmimPF6 was used. This effect is probably due to changes in the structure of Lip1 induced by the presence of these ionic liquids, stimulating its catalytic activity.     

Bench-Scale and Pilot-Scale Treatment Technologies for the Removal of Total Dissolved Solids from Coal Mine Water: A Review

Coal mine water (CMW) is typically treated to remove suspended solids, acidity, and soluble metals, but high concentrations of total dissolved solids (TDS) have been reported to impact the environment at several CMW discharge points. Consequently, various states have established TDS wastewater regulations and the US EPA has proposed a benchmark conductivity limit to reduce TDS impacts in streams near mining sites. Traditional CMW treatment effectively removes some TDS components, but is not effective in removing major salt ions due to their higher solubility. This paper describes the basic principles, effectiveness, advantages, and disadvantages of various TDS removal technologies (adsorption, bioremediation, capacitive deionization, desalination, distillation, electrochemical ion exchange, electrocoagulation, electrodialysis, ion exchange, membrane filtration, precipitation, and reverse osmosis) that have at least been tested in bench- and pilot-scale experiments.     

Steam and carbon dioxide activation of Eucalyptus globulus charcoal

The partial gasification of Eucalyptus globulus charcoal, using carbon dioxide and steam as activating agents is studied. The influence of some preparation variables such as temperature and reaction time on textural, morphological and acid–base properties are given. The results obtained show that both activating agents produce microporous activated carbons and that a large increase in meso- and macroporosity is observed when steam and high burn-off are used. It has been found that these activated carbons have weak acid sites and the effect of the burn-off on the acid strength depends on the activating agent. Thus, the acid strength of these sites decreases with the burn-off when steam is used, but no effect is observed when carbon dioxide is used.     

Praseodymium based high-k dielectrics grown on Si and SiC substrates

High-k polycrystalline Pr₂O₃ thin films have been deposited by metal organic chemical vapor deposition (MOCVD) technique on Si(0 0 1) and 4H–SiC(0 0 0 1) substrates. MOCVD processes have been carried out from the Pr(tmhd)₃ (H-tmhd= 2,2,6,6-tetramethyl-3,5-heptandione) precursor. Complete structural and morphological characterization of films has been carried out using several techniques (X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM)). Polycrystalline Pr₂O₃ films have been obtained and at the interface a praseodymium silicate amorphous layer has been observed on both substrates. The electrical properties of the dielectric praseodymium films have been evaluated.     

Strategies Towards Sustainable Development in Nigeria's Semi-Arid Regions

During the last three decades, there has been a steady decline in rainfall within Northern Nigeria where the total annual amount has declined below the 30-year mean; this could be either a permanent or temporary phenomenon. Whatever the trend, the continuous deterioration in climatic conditions, combined with uncoordinated resources planning, are paving the way for a crisis of dramatic proportions in the sub-region. In the rush to combat this threat, like most third-world countries, Nigeria embarked upon large-scale constructions of dams and irrigation-infrastructure facilities without proper planning and coordination. Consequently, the schemes have now failed to achieve their forecast output.
The paper attempts to establish the important role which the naturally available water-resources potential of the sub-region could play towards sustainable irrigated agricultural development under increasing risks of drought and desertification within the area.     

An outbreak of hantavirus pulmonary syndrome, Chile, 1997

A novel splice variant of RGS 9 was isolated from a rat hypothalamus, human retina, and a human kidney (Wilm's) tumor. This variant, termed RGS 9L, differs from the retinal form (termed RGS 9S) identified previously in that it contains a 211- (rat) or 205- (human) amino acid proline-rich domain on the carboxyl terminus. The pattern of RGS 9 mRNA splicing was tissue specific, with striatum, hypothalamus- and nucleus accumbens expressing RGS 9L, whereas retina and pineal expressed RGS 9S almost exclusively. This pattern of mRNA splicing seemed to be highly conserved between human and rodents, suggesting cell-specific differences in the function of these variants. Transient expression of RGS 9L augmented basal and beta-adrenergic receptor-stimulated adenylyl cyclase activity while suppressing dopamine D2 receptor-mediated inhibition. Furthermore, RGS 9L expression greatly accelerated the decay of dopamine D2 receptor-induced GIRK current. These results indicate RGS 9L inhibits heterotrimeric Gi function in vivo, probably by acting as a GTPase-activating protein. The human RGS 9 gene was localized to chromosome 17 q23-24 by radiation hybrid and fluorescent in situ hybridization analyses. The RGS 9 gene is within a previously defined locus for retinitis pigmentosa (RP 17), a disease that has been linked to genes in the rhodopsin/transducin/cGMP signaling pathway.     

Assessing an ambulance service with queuing theory

We describe an ambulance service in terms of its main operation parameters and strategic decision variables. Assisted by queuing theory, we calculate the key performance indicators (KPI) that concern the manager and the KPI that concern the patient. We use them to improve the operation of a private ambulance service in Chile. First, we evaluate whether the historical performance is consistent with the resources deployed. Then, we estimate the impact of some operational enhancements, such as reducing the cycle time or enlarging the fleet. Finally, we optimize the geographical coverage of the bases. We conclude that simple mathematical expressions are very useful to evaluate and improve the operation.     

The value of information in a long–term hydro–thermal electrical planning model

This article presents the analysis, comparison, and application of two alternative models to the optimal long–term operation planning of an hydro–thermal power system under conditions of uncertainty. The electrical system considered comprises one large reservoir, with interannual regulation capacity, and several smaller ones. The analyzed models employ stochastic dynamic programming as the solution methodology. The fundamental problem is to decide, on every temporal stage, how much water to use for generating purposes and how much to store, in order to minimize the total thermal and shortage costs. The original version of the studied model, created originally to forecast fuel consumption, assumes that the decision regarding the water release from the main reservoir is taken knowing the future hydrologic conditions. This criterion is known as wait–and–see . On the contrary, the new versions of the model, proposed in this article, consider a here–and–now criterion. Specifically, it is assumed that the future hydrologic conditions are not known at the time of making the operational decisions. The difference between the optimal cost of the proposed models and the original model defines the value of having the information regarding future hydrologic conditions before taking any decision. This value is generally known as the expected value of perfect information.