Comparison between Eulerian and Lagrangian semi-analytical models to simulate the pollutant dispersion in the PBL

In this work we display a numerical comparison, under statistical and computational point of view, between semi-analytical Eulerian and Lagrangian dispersion models to simulate the ground-level concentration values of a passive pollutant released from a low height source. The Eulerian approach is based on the solution of the advection–diffusion equation by the Laplace transform technique. The Lagrangian approach is based on solution of the Langevin equation through the Picard’s Iterative Method. Turbulence inputs are calculated according to a parameterization capable of generating continuous values in all stability conditions and in all heights of the Planetary Boundary Layer (PBL). Numerical simulations and comparisons show a good agreement between predicted and observed concentrations values. The comparison reveals the main advantages and disadvantages between the models.     

Large-scale production of cellulose-binding domains. Adsorption studies using CBD-FITC conjugates

A method for the gram-scale production of cellulose-binding domains (CBD) through the proteolytic digestion of a commercial enzymatic preparation (Celluclast) was developed. The CBD obtained, isolated from Trichoderma reesei cellobiohydrolase I, is highly pure and heavily glycosylated. The purified peptide has a molecular weight of 8.43 kDa, comprising the binding module, a part of the linker, and about 30% glycosidic moiety. Its properties may thus be different from recombinant ones expressed in bacteria. CBD-fluorescein isothiocyanate conjugates were used to study the CBD-cellulose interaction. The presence of fluorescent peptides adsorbed on crystalline and amorphous cellulose fibers suggests that amorphous regions have a higher concentration of binding sites. The adsorption is reversible, but desorption is a very slow process.     

Oscillatory Perturbations of Linear Problems at Resonance

This paper is concerned with a study of bounded perturbations of resonant linear problems. It follows from our results that for certain types of bounded domains Ω ? Rⁿ, n ≥ 2, the Dirichlet problem $\matrix{\Delta u+\lambda_{1}u+g(u)=h(x),\ \ \ x\in\Omega\cr \quad\quad\quad\quad\quad\quad u=0,\ \ \ x\in\partial\Omega,}$ has infinitely many positive solutions, in case λ₁ is the principal eigenvalue of ?Δ subject to trivial Dirichlet boundary conditions, g is a nontrivial periodic nonlinearity of zero mean and ∫_03A9h(x)?(x)dx = 0, where ? is an eigenfunction corresponding to λ₁.     

Comparison of the performance of graphitized carbon black and poly(styrene-divinylbenzene) cartridges for the determination of pesticides and industrial phosphates in environmental waters

The determination of polar and nonpolar organophosphorus compounds, triazines and their metabolites, molinate and chlorothalonil in 1 l water samples was investigated using off-line solid-phase extraction followed by gas chromatography with nitrogen-phosphorus and flame photometric detection. The ethylvinylbenzene-divinylbenzene copolymer (LiChrolut EN) and the commercial graphitized carbon black (GCB) of Envi-Carb were tested as solid-phase sorbents. The matrix effect was studied by extracting the compounds spiked in water samples of different types (Milli-Q, tap, salted tap water, river and sea water). The polymeric sorbent LiChrolut EN allowed the determination at low ng/l of all 40 compounds tested, except the very polar atrazine-desethyl-deisopropyl (DDA). Recoveries of compounds from the Envi-Carb sorbent are comparable to those obtained for LiChrolut EN with the exception of chlorothalonil and the more hydrophobic organophosphorus compounds (coumaphos, leptophos), which were strongly sorbed in the Envi-Carb cartridges. Envi-Carb, however, enabled the determination of DDA with a limit of detection of 14 ng/l.     

Molecular weight effect on the photoinduced birefringence and surface relief gratings formation of a methacrylate azopolymer

Samples of a methacrylic side-chain azopolymer were synthesized by a radical copolymerization of methyl-methacrylate with the methacrylic derivative of the commercial dye Disperse Red-13 (DR13). Copolymers with different molecular weight were obtained by varying the reaction time and the concentration of initiator. Samples with molecular weight averages (M_w) from 3 to 8 × 10⁴ g/mol and 1.4-1.7 polydispersity were obtained. The glass transition temperature of the samples increased linearly from the lower to the highest molecular weight. Optical quality cast films were prepared for all samples and photoinduced birefringence was successfully carried out in all samples as well as surface relief gratings could be inscribed in the cast films.     

Simulation of aerated lagoon using artificial neural networks and multivariate regression techniques

The aim of this study was to develop an empirical model that provides accurate predictions of the biochemical oxygen demand of the output stream from the aerated lagoon at International Paper of Brazil, one of the major pulp and paper plants in Brazil. Predictive models were calculated from functional link neural networks (FLNNs), multiple linear regression, principal components regression, and partial least-squares regression (PLSR). Improvement in FLNN modeling capability was observed when the data were preprocessed using the PLSR technique. PLSR also proved to be a powerful linear regression technique for this problem, which presents operational data limitations.     

Complexation of the Non-steroidal Anti-inflammatory Drug Nabumetone with Modified and Unmodified Cyclodextrins

The inclusion of the anti-inflammatory drug, Nabumetone, in -, - and hydroxypropyl--cyclodextrin (CDs) is studied using UV-VIS absorption and steady-state fluorescence emission. Binding constants and thermodynamic parameters of complex formation are determined by spectrofluorimetry. The inclusion phenomena of Nabumetone with the three cyclodextrins is compared with that of the well known similar anti-inflammatory drug Naproxen. In the case of Nabumetone pronounced differences are observed in the complexation process with each cyclodextrin whereas the respective Naproxen complexes are nearly identical. ¹H-NMR experiments show that the inclusion process in Nabumetone can occur either through the substituents in the -2 (butanone) or -6 (methoxy) positions in the naphthalene ring.     

Conversion electron and X-ray Mössbauer studies of boronized low-carbon steel under corrosion and oxidation conditions

Iron-boride layers on low-carbon steel were produced by thermochemical diffusion process. The surface interaction products: Fe₂B, FeB, FeB_x (x>1) and a solid solution of iron in boron were identified by surface Mössbauer spectroscopy (CEMS and XMS). Samples of original and boronized steel were subjected to corrosion process by immersion in HCl (0.1 N) solution for 150 h. While the steel sample was strongly corroded, none corrosion product was found on the boronized sample surface. However, significant changes in relative percentages of the various iron boride phases were detected. Also, samples of original and boronized steel were subjected to oxidation process by heat-treatment in air at 300°C for 8 h and 500°C for 4 h. At 300°C, while bulk Fe₃O₄ and -Fe₂O₃ were formed on the steel surface, none iron oxide was detected on the boronized surface. At 500° C, while only pure bulk -Fe₂O₃ was detected on the steel surface, a particle size distribution of-Fe₂O₃, with particle size of about 100 Å, was probably formed on the boronized surface, as evidenced by CEMS.     

Phase transfer of metal cations by induced dynamic carrier agents: biphasic extraction based on dynamic covalent chemistry

In contrast to the classical method where a single molecule is designed to extract metal cations under specific conditions, dynamic covalent chemistry provides an approach based on the implementation of an adaptive dynamic covalent library for inducing the generation of the extractant species. This approach has been applied to the liquid–liquid extraction of copper(ii) nitrate based on a dynamic library of acylhydrazones constituents that self-build and distribute through the interface of a biphasic system. The addition of copper(ii) cations to this library triggers a modification of its composition and the up-regulation of the ligand molecules driven by coordination to the metal cations. Among these, one species has proven to be sufficiently lipophilic to play the role of carrier agent and its formation by component exchange enables the partial extraction of the copper(ii). The study of different pathways to generate the dynamic covalent library demonstrates the complete reversibility and the adaptability of the system. The detailed analytical investigation of the system provides a means to assess the mechanism of the dynamic extraction process.

Phase transfer of Cu(ii) cations is achieved by component exchange in a dynamic covalent library of acylhydrazone ligands. B1/B2 component exchange leads to the generation of a lipophilic carrier agent that extracts Cu(ii) into chloroform.