Covalent coupling of antibodies to aldehyde groups on polymer carriers

The aim of the present work is to prepare and characterize a functionalized latex with acetal groups on the surface and to obtain the covalent coupling of an a-CRP IgG protein. The acetal latex was synthesized by means of a core-shell emulsion polymerization in a batch reactor. The core was a seed of polystyrene and the shell was obtained by terpolymerization of styrene, methacrylic acid and methacryloylacetaldehyde di(n.methyl)acetal. The latex was characterized by TEM and conductimetric and potentiometric titration, in order to obtain the particle size distribution and the amount of carboxyl and acetal groups on the surface, respectively. Several latex-protein particles with the IgG physically or chemically bound to the surface were obtained by modifying the incubation conditions. In the covalent coupling experiments of the IgG, the protein physically adsorbed was removed by redispersion of the complexes in the presence of a non-ionic surfactant (Tween 20). The latex-protein complexes were characterized from the electrokinetic point of view with the aim to determine the isoelectric point of the complexes and to detect any difference in the electric state of the protein when these molecules are physically or chemically coupled to the surface. The final part of this work was to study the immunoreactivity of several latex-IgG complexes at several experimental conditions. By measuring the change in the turbidity after the addition of CRP antigen into the dispersion, it was possible to compare the immunoreactivity results when the protein is physically or chemically bound to the surface, and to study the effect of the presence of a surfactant in the reaction medium.     

Color and spectral analysis of daylight in southern Europe

We have analyzed the colorimetric and spectral characteristics of 2600 daylight spectra (global spectral irradiances on a horizontal surface) measured for all sky states during a 2-year period at Granada, Spain. We describe in detail the chromaticity coordinates, correlated color temperatures (CCT), luminous efficacies, and relative UV and IR contents of Granada daylight. The chromaticity coordinates of Granada daylight lie far above the CIE locus at high CCTs (>9,000 K), and a CCT of 5,700 K best typifies this daylight. Our principal-components analysis shows that Granada daylight spectra can be adequately represented by using six-dimensional linear models in the visible, whereas seven-dimensional models are required if we include the UV or near-IR. Yet on average only three-dimensional models are needed to reconstruct spectra that are colorimetrically indistinguishable from the original spectra.     

Cell-associated hemolytic activity in environmental strains of Plesiomonas shigelloides expressing cell-free, iron-influenced extracellular hemolysin

Hemolysis is a means of providing pathogenic bacteria with heme iron in vivo. In a previous work, iron-influenced hemolytic activity against sheep erythrocytes was detected in cell-free supernatants, but not in the cell fraction of two environmental Plesiomonas shigelloides strains incubated without shaking. Both strains have the hugA gene, which encodes an outer membrane receptor required for heme iron utilization. The present study was undertaken to investigate the expression of a second hemolytic activity detected during aerated incubation in normal and iron-depleted tryptone soya broth (id-TSB). An agar overlay procedure and doubling dilution titrations were employed to detect the hemolytic activity against several erythrocyte species. The kinetics of growth and hemolytic activity were assayed at 35 degrees C in aerated normal and id-TSB and salmon extract. Overlaid colonies showed a cell-associated beta-hemolytic activity within 4 h. For aerated cell-free supernatants, titers above 16 were not attained until 30 to 48 h of incubation; the best activity was noted with dog and mouse erythrocytes. After 24 h of aerated incubation, sonicated cells yielded high hemolytic activity against dog erythrocytes without activity in supernatants, but after 48 h, only 28 to 30% of the total activity remained cell associated. The hemolytic factor was released in broths during the death phase. Hemolytic activity was not detected in fish extract. This and other studies suggest that P. shigelloides may produce at least two hemolytic factors, their expression and detection being influenced by environmental growth conditions and testing procedures. The overlay assay appears to be the best routine method for detecting hemolytic activity in P. shigelloides.     

Fatty Acid Profiles of Virgin Olive Oils from the Five Olive-Growing Zones of Extremadura (Spain)

In this study, 278 samples of virgin olive oil from 40 mills belonging to five olive-growing zones of Extremadura were evaluated according to their fatty acid composition. An analysis of variance of the fatty acid contents, and their principal group subtotals and ratios revealed significant differences at the 95 % confidence level between zones. Means were compared using Tukey’s HSD test (p < 0.05). A discriminant analysis, taking the zone as the grouping variable and the different fatty acids and their ratios as independent variables, explained nearly 90 % of the variance with the first two functions. The model correctly classified 88.8 % of the analysed samples into their proper olive-growing zone. Validation against an extra test set of 30 samples resulted in 90 % being correctly classified; the results of the discriminant analysis were therefore considered to be validated. A two-dimensional graphical representation of the different groups studied using the first two resulting canonical discriminant functions clearly showed the Sierra Norte of Cáceres and Vegas del Guadiana each to be clearly separated from the rest and from each other, while the other three zones—Siberia, Serena and Tierra de Barros—overlapped considerably.     

Spectral-daylight recovery by use of only a few sensors

Linear models have already been proved accurate enough to recover spectral functions. We have resorted to such linear models to recover spectral daylight with the response of no more than a few real sensors. We performed an exhaustive search to obtain the best set of Gaussian sensors with a combination of optimum spectral position and bandwidth. We also examined to what extent the accuracy of daylight estimation depends on the number of sensors and their spectral properties. A set of 2600 daylight spectra [J. Opt. Soc. Am. A 18, 1325 (2001)] were used to determine the basis functions in the linear model and also to evaluate the accuracy of the search. The estimated spectra are compared with the original ones for different spectral daylight and skylight sets of data within the visible spectrum. Spectral similarity, colorimetric differences, and integrated spectral irradiance errors were all taken into account. We compare our best results with those obtained by using a commercial CCD, revealing the CCD's potential as a daylight-estimation device.     

A Very Highly Efficient Magnetic Nanomaterial for the Removal of PAHs from Aqueous Media

Two new hybrid magnetic recyclable nanomaterials are developed. These new materials are based on bisimide perylene dopamine or bisimide perylene 3‐aminopropyltriethoxysilane and iron oxide nanoparticles. One of them, the bisimide perylene dopamine, has proven to be very efficient in the removal, by magneto filtration, of 15 carcinogenic polycyclic aromatic compounds (PAHs), especially naphthalene, acenaphthene, anthracene, phenanthrene, and fluorene. These compounds are known to be common contaminants of drinking and underground water. This nanomaterial presents a high dispersivity and stability in an aqueous media, and it is capable of forming supramolecular fluorescent magnetic nanofibers with benzo‐alpha‐pyrene or benzo[k]fluoranthene, BKF. This strong association is due to hydrophobic forces and the π–π interaction, between the bisimide perylene motif and the polycyclic aromatic compounds. The resilience of this material is tested in different media. No good results are obtained in ethanol, acetone, or acetonitrile, but an 85% recovery is achieved using toluene or hexane. Once washed, nanoparticles are shown to retain their ability to continue capturing PAHs.