FTIR study of the oxidation reaction of CO with O2 over bimetallic Pd–Rh/SiO2 catalysts in an oxidized state

CO species adsorbed on the surface of oxidized bimetallic Rh–Pd catalysts, prepared by coimpregnation and sequential impregnation methods, were analyzed in situ by IR spectroscopy, during the reaction of CO with O₂ in an oxidizing atmosphere. The results show that the two methods of impregnation lead to the existence of oxidized Rh on the surface of the bimetallic catalyst, however, in the case of the sequential impregnation method, the Pd surface is more reduced than in the case of catalysts prepared by coimpregnation. The simultaneous presence of reduced Pd and oxidized Rh that occurs in the catalysts prepared by sequential impregnation allows the existence of a synergistic effect similar to that proposed in the literature for the Pt–Rh system. The lower degree of oxidation of the Pd in the catalysts prepared by sequential impregnation, is mainly due to the fact that the Pd in these catalysts comes from the organic precursor palladium acetylacetonate, while in the catalysts prepared by coimpregnation, the Pd comes from the precursor PdCl₂. This revised version was published online in July 2006 with corrections to the Cover Date.     

Eosinophil cationic protein in the asthmatic infant: correlation with the clinic and pulmonary function

PATIENTS AND METHODS: Serum eosinophil cationic protein (ECP) was measured in 99 chronic asthmatic patients (51 males and 48 females) with a mean age of 10.59 years and correlated with the number of eosinophils, lung function, symptoms in the last 6 months and clinical scoring (that reflecting the clinical situation during the last 15 days). RESULTS: Serum ECP showed a significant correlation with the total number of eosinophils (p < 0.001, R = 0.44), clinical scoring (p < 0.05, R = 0.26), number of inhaled beta 2-agonist doses needed in the last 15 days (p < 0.05, R = 0.26), forced expiratory volume during 1 second (FEV1; p < 0.01, R = -0.27), forced vital capacity (FVC; p < 0.05, R = -0.23), maximal mid-expiratory flow (FEF25-27; p < 0.001, R = -0.37). However, there was no significant correlation between the total number of eosinophils and the clinical situation of the children or the FEV1, but we found a significant correlation with the FEF25-27. Patients with ECP < 20 had better results on lung function tests than patients with ECP > 20 (FEV1: 108.89 +/- 17.7 vs 100.5 +/- 22 (p < 0.05), FEF25-27: 93.81 +/- 24.4 vs 75.21 +/- 24.5 (p < 0.001). CONCLUSIONS: The findings of this study suggest that the ECP level is a good marker of the situation of asthma in childhood. The levels of ECP will probably be able to help us to evaluate the degree of bronchial inflammation that neither the clinical state nor the lung function define completely.     

Adaptive control with finite time persistency of excitation

An adaptive control algorithm for discrete-time SISO systems is presented. The main feature is the fact that it requires an external persistently exciting signal for a finite interval of time. In this way tracking of a class of signals (such as set points) can be achieved within an arbitrarily small error.     

Sodium Caseinate/Sunflower Oil Emulsion-Based Gels for Structuring Food

Protein gels have attired attention since they allow structuring foods with no trans or saturated fats. The effects of protein concentration and sucrose addition on gelation kinetics and on physical properties of sodium caseinate (NaCas)/sunflower oil emulsion-based gels were studied by two methods: a new application of backscattering of light (BS) using a Turbiscan equipment and by dynamic oscillatory rheology. Structure of gels was also described by confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). T _gel values decreased with increasing sucrose or NaCas concentration. BS method sensed early changes in structure, while rheological measurements were less sensitive to those changes. However, tendencies found by rheological measurements were the same as the ones found by BS experiments. CLSM images of gels formed from emulsions containing high sucrose and protein concentrations had big oil droplets that were not present in initial emulsions. Gels with sucrose concentrations between 15 and 30 wt/wt% released oil. SAXS patterns showed that NaCas nanoaggregate sizes in the aqueous phase were smaller with increasing sucrose concentration. Polar groups of protein interacted with sucrose, and therefore, interactions among protein molecules diminished. As a result of weaker protein molecule interactions, nanoaggregates were smaller. However, this effect was beneficial. In the macroscale, rheological properties and visual appearance of gels were improved. The gel formulated with 5 wt/wt% NaCas and 10 wt/wt% sucrose had a smooth surface and was stable to syneresis and oil release. This formulation was a good alternative to trans fat.     

Study of dissolution behavior of matrices tablets based on alginate-gelatin mixtures as prolonged diltiazem hydrochloride release systems

The aim of this work was to develop prolonged diltiazem hydrochloride release matrices based on alginate-gelatin mixtures and establish the drug release mechanism. The erosion, swelling, and dissolution behavior of the tablets in different medium were evaluated. The different polyelectrolyte behavior and gel strength between type A Gelatin and type B Gelatin would explain the different swelling, erosion and dissolution behavior in the media with sudden pH change. The similar dissolution behavior in the pH, which simulates the physiological pH through the gastrointestinal tract, should be explained because the same main species for gelatin A and Gelatin B would be present in this media.