It is the first time that the removal of polycyclic aromatic hydrocarbons (PAH) containing different aromatic rings number [naphthalene (Np), phenanthrene (Phe), and pyrene (Py)] from combustion hot gas has been carried out. The aim was to relate the sorbents textural characteristics with the adsorption capacity of these 2-4-ring PAH at the conditions emitted at energy generation. The sorbents textural parameters [total micropore volume (VN2), narrow micropore volume (VCO2), mesopore volume (VBJH), and the free active sites] were analyzed trying to correlate them with their Np, Phe, and Py adsorption capacities. To get this aim, single and multiple linear regressions (MLR) were applied to the three PAH. A principal component analysis was performed to generate new and uncorrelated variables. It enabled us to show that the relations between the textural parameters were analyzed using a principal components regression (PCR). The PCR analysis had a good statistical quality, but neither did it allow differentiating free active site types nor did VN2 and VCO2. The correlations were thus set up applying a MLR to the original variables. The regression statistical quality was similar to the PCR analysis, and it could give an easier explanation of the parameters that affected the adsorption. In Np adsorption, the 87% data variance was explained, and the adsorption was positively correlated to VCO2 and the micropore mean diameter (I.). In the Phe regression there was 98% variance explained, and its adsorption was positively correlated to the VN2 and the micropore distribution, n. Finally, in the Py adsorption, the 96% data variance was explained, and this adsorption was positively correlated to VN2 and VBJH. These dependencies were according to the molecular parameters of these compounds (molecular diameter and volatility) because the higher the number of aromatic rings of the PAH, the more favored the adsorbate-adsorbate interactions. Besides, the higher the mean diameter micropores, the lower the diffusional problems showed by Np, Phe, and Py.

This review (with 106 references) mainly deals with the analytical applications of flavin-adenine dinucleotide (FAD) fluorescence. In the first section, the spectroscopic properties of this compound are reviewed at the light of his different acid-base, oxidation and structural forms; the chemical and spectroscopic properties of flavin mononucleotide (FMN) and other flavins will be also briefly discussed. The second section discusses how the properties of FAD fluorescence changes in flavoenzymes (FvEs), again considering the different chemical and structural forms; the glucose oxidase (GOx) and the choline oxidase (ChOx) cases will be commented. Since almost certainly the most reported analytical application of FAD fluorescence is as an auto-indicator in enzymatic methods catalysed by FvE oxidoreductases, it is important to know how the concentrations of the different forms of FAD changes along the reaction and, consequently, the fluorescence and the analytical signals. An approach to do this will be presented in section 3. The fourth part of the paper compiles the analytical applications which have been reported until now based in these fluorescence properties. Finally, some suggestions about tentative future research are also given.

We report on upconverting luminescent nanoparticles (UCLNPs) that are spectrally tuned such that their emission matches the absorption bands of the two most important species associated with enzymatic redox reactions. The core-shell UCLNPs consist of a β-NaYF4 core doped with Yb(3+)/Tm(3+) ions and a shell of pure β-NaYF4. Upon 980 nm excitation, they display emission bands peaking at 360 and 475 nm, which is a perfect match to the absorption bands of the enzyme cosubstrate NADH and the coenzyme FAD, respectively. By exploiting these spectral overlaps, we have designed fluorescent detection schemes for NADH and FAD that are based on the modulation of the emission intensities of UCLNPs by FAD and NADH via an inner filter effect.

This is the first time that the adsorption of phenanthrene (Phe) for hot gas emissions cleaning from combustion has been studied. For this goal, the adsorption capacity of 10 active carbons with different origins and a wide range of textural characteristics has been assessed for Phe removal from hot gas emissions. The study was carried out at laboratory scale and the main aim has been to test the Phe adsorption capacities by the porous materials at the ranges that Phe could be emitted from new energy systems generation. The protocol followed in this work was the following: first, to check the influence of the bed mass on the Phe adsorption capacity, and second, once it was shown that the bed mass is not relevant for the studied Phe concentration range, the adsorption capacity of the 10 adsorbents was analyzed. The CA-3 adsorbent was selected to check the inlet concentration at three different temperatures, 125, 150, and 175 °C, within the range of atmospheric emissions from the power stations. The results obtained show that there is a good correlation between the Phe adsorption capacity and the total micropore volume calculated with the Dubinin-Radushkevich equation for the N 2 isotherm data. No relationship was found between Phe adsorption capacity and mesopore volume calculated by BJH method. Besides, no relationship was found between chemical surface (CO and CO 2 groups desorbed on thermal program desorption (TPD)) and adsorption capacity.

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In this paper an in depth study is presented of the use of the horseradish peroxidase (HRP) enzyme as a self-indicating biorecognition reagent in UV-vis molecular absorption spectrometry. The HRP/H2O2 reaction mechanism in the absence of an external substrate has been clarified, and the interaction between HRP and glucose oxidase (GOx) has been studied. It has been demonstrated that GOx can act as a substrate of HRP; in both cases the kinetic constants have been obtained and mathematical models have been developed. Second, the HRP/H2O2 reaction is used to follow a H2O2-producing enzymatic reaction, the glucose reaction with GOx being used as a model. As an application of this, two methodologies have been proposed for glucose determination: with or without previous incubation of glucose with GOx. In both cases mathematical models relating HRP absorbance changes to glucose concentration have been developed and tested; both methods have been optimized, analytically characterized, and tested for glucose determination in samples. The methodology described could be applied to other heme-proteins and to other H2O2-producing enzymatic reactions. The models permit the reaction constants to be calculated. From the analytical chemistry point of view the models allow the prediction of the method sensitivity for other analytes involved in this type of reaction if the kinetic constants are known and can be used in the design of optical sensors.

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