Liquid-vapor equilibrium of the systems butylmethylimidazolium nitrate-CO2 and hydroxypropylmethylimidazolium nitrate-CO2 at high pressure: influence of water on the phase behavior

Ionic liquids (IL) are receiving increasing attention due to their potential as "green" solvents, especially when used in combination with SC-CO2. In this work liquid-vapor equilibria of binary mixtures of CO2 with two imidazolium-based ionic liquids (IL) with a nitrate anion have been experimentally determined: butylmethylimidazolium nitrate (BMImNO3) and hydroxypropylmethylimidazolium nitrate (HOPMImNO3), using a Cailletet apparatus that operates according to the synthetic method. CO2 concentrations from 5 up to 30 mol % were investigated. It was found that CO2 is substantially less soluble in HOPMImNO3 than in BMImNO3. Since these ILs are very hygroscopic, water easily can be a major contaminant, causing changes in the phase behavior. In case these Ils are to be used in practical applications, for instance, together with CO2 as a medium in supercritical enzymatic reactions, it is very important to have quantitative information on how the water content will affect the phase behavior. This work presents the first systematic study on the influence of water on the solubility of carbon dioxide in hygroscopic ILs. It was observed that the presence of water reduces the absolute solubility of CO2. However, at fixed ratios of CO2/IL, the bubble point pressure remains almost unchanged with increasing water content. In order to explain the experimental results, the densities of aqueous mixtures of both ILs were determined experimentally and the excess molar volumes calculated.     

Application of partial least squares discriminant analysis and variable selection procedures: a 2D-PAGE proteomic study

2D gel electrophoresis is a tool for measuring protein regulation, involving image analysis by dedicated software (PDQuest, Melanie, etc.). Here, partial least squares discriminant analysis was applied to improve the results obtained by classic image analysis and to identify the significant spots responsible for the differences between two datasets. A human colon cancer HCT116 cell line was analyzed, treated and not treated with a new histone deacetylase inhibitor, RC307. The proteins regulated by RC307 were detected by analyzing the total lysates and nuclear proteome profiles. Some of the regulated spots were identified by tandem mass spectrometry. The preliminary data are encouraging and the protein modulation reported is consistent with the antitumoral effect of RC307 on the HCT116 cell line. Partial least squares discriminant analysis coupled with backward elimination variable selection allowed the identification of a larger number of spots than classic PDQuest analysis. Moreover, it allows the achievement of the best performances of the model in terms of prediction and provides therefore more robust and reliable results. From this point of view, the multivariate procedure applied can be considered a good alternative to standard differential analysis, also taking into account the interdependencies existing among the variables.     

Site-selectivity of protonation in gaseous toluene

The favoured protonation sites leading to isomeric toluenium ions have been assayed, envisaging the mildest possible route for proton transfer to naked toluene.     

Analysis of human carbonic anhydrase II: docking reliability and receptor-based 3D-QSAR study

The ability of Gold software to predict the binding disposition of carbonic anhydrase (CA) inhibitors was evaluated using CA II as a case study. The best procedure was subsequently used for docking almost 300 CA II ligands, and the best poses were used as an alignment tool for the development of a 3D quantitative structure-activity relationship (QSAR) study. Evaluation of the resulting 3D-QSAR model allowed us to indicate the ligand properties and residues important for CA II inhibition. Since CAs are an important target involved in many pathologies such as glaucoma, obesity, and tumors, the results obtained could accurately predict the binding affinity of newly designed CA II inhibitors. Furthermore, it is reasonable that this strategy could be profitably used also for the investigation of other CAs.     

Structural characterization of the sol–gel oxide powders from the ZnO–TiO2–SiO2 system

This work is a study that deals with the synthesis by the sol–gel method and the structural characterization of the oxide powders belonging to the ternary system ZnO–TiO₂–SiO₂ (ZTS). The sol–gel synthesis starts from inorganic precursors, which have been processed under the variation of different technological parameters. We have investigated the dependence of the gelling time on pH and on the temperature of synthesis as well as on water and ammonia amounts. In the case of ZTS samples, the shortest gelling duration appears for low pH values when ZnO content is increased and at small ammonia concentrations when the ZnO content is decreased, respectively. On the contrary, ZTS samples containing high amounts of TiO₂ provide evidence of a short gelling time for high pH and large ammonia amounts. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy provided structural information on these ternary oxide powders. These analyses revealed that relative high amounts of ZnO yields in a change from octahedral [ ZnO₆] units to tetrahedral [ ZnO₄] units in the powder structure. Optical phonons specific for SiO₂ and TiO₂ in both octahedral and tetrahedral groups are shown. High thermal and chemical stability was put in evidence by differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA) in the 20–1000 C temperature range.     

Micro-bioreactor array for controlling cellular microenvironments

High throughput experiments can be used to spatially and temporally investigate the many factors that regulate cell differentiation. We have developed a micro-bioreactor array (MBA) that is fabricated using soft lithography and contains twelve independent micro-bioreactors perfused with culture medium. The MBA enables cultivation of cells that are either attached to substrates or encapsulated in hydrogels, at variable levels of hydrodynamic shear, and with automated image analysis of the expression of cell differentiation markers. The flow and mass transport in the MBA were characterized by computational fluid dynamic (CFD) modeling. The representative MBA configurations were validated using the C2C12 cell line, primary rat cardiac myocytes and human embryonic stem cells (hESCs) (lines H09 and H13). To illustrate the utility of the MBA for controlled studies of hESCs, we established correlations between the expression of smooth muscle actin and cell density for three different flow configurations.     

Applications of stable isotope ratio mass spectrometry in cattle dung carbon cycling studies

Understanding the fate of dung carbon (C) in soils is challenging due to the ubiquitous presence of the plant‐derived organic matter (OM), the source material from which both dung‐derived OM and soil organic matter (SOM) predominantly originate. A better understanding of the fate of specific components of this substantial source of OM, and thereby its contribution to C cycling in terrestrial ecosystems, can only be achieved through the use of labelled dung treatments. In this short review, we consider analytical approaches using bulk and compound‐specific stable carbon isotope analysis that have been utilised to explore the fate of dung‐derived C in soils. Bulk stable carbon isotope analyses are now used routinely to explore OM matter cycling in soils, and have shown that up to 20% of applied dung C may be incorporated into the surface soil horizons several weeks after application, with up to 8% remaining in the soil profile after one year. However, whole soil δ¹³C values represent the average of a wide range of organic components with varying δ¹³C values and mean residence times in soils. Several stable ¹³C isotope ratio mass spectrometric methods have been developed to qualify and quantify different fractions of OM in soils and other complex matrices. In particular, thermogravimetry‐differential scanning calorimetry‐isotope ratio mass spectrometry (TG‐DSC‐IRMS) and gas chromatography‐combustion‐IRMS (GC‐C‐IRMS) analyses have been applied to determine the incorporation and turnover of polymeric plant cell wall materials from C₄ dung into C₃ grassland soils using natural abundance ¹³C isotope labelling. Both approaches showed that fluxes of C derived from polysaccharides, i.e. as cellulose or monosaccharide components, were more similar to the behaviour of bulk dung C in soil than lignin. However, lignin and its 4‐hydroxypropanoid monomers were unexpectedly dynamic in soil. These findings provide further evidence for emerging themes in biogeochemical investigations of soil OM dynamics that challenge perceived concepts of recalcitrance of C pools in soils, which may have profound implications for the assessment of the potential of agricultural soils to influence terrestrial C sinks. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and characterization of Co@Ag core–shell nanoparticles

Journal of Nanoparticle Research - A micellar method has been used to prepare silver-coated cobalt (Co@Ag) nanoparticles. The synthesized particles have been deeply characterized by several...     

On the longevity of H-mediated ferromagnetism in Co doped TiO2: A study of electronic and magnetic interplay

Recent studies on dilute magnetic semiconductors have largely been focused on hydrogen induced giant magnetization. On the contrary, there are hardly any attempts to establish whether the H-induced magnetization is a permanent feature or likely to degrade with time. This aspect warrants a firm confirmation prior to planning their possible applications in spintronics and microelectronics. Motivated by this, we have systematically investigated this behaviour in Co doped TiO₂. In one study, we gave successive re-heat treatment to hydrogenated pellets and studied their magnetic, transport and electronic properties versus re-heating time. In another, we stored the hydrogenated sample in dry atmosphere for several months and studied the ageing effect on the induced ferromagnetism. The H-induced magnetization quickly vanishes upon re-heating the specimen; in addition, it also tends to degrade gradually with passage of time. The electronic and transport properties show a close parallelism, without any departure from structural properties. On the other hand, the Co-induced ferromagnetism, albeit a weak effect, does not show such degradation effects. As regards the mechanism of ferromagnetism, the oxygen vacancies are suggested to mediate the coupling.