A volatolomic approach using cerumen as biofluid to diagnose bovine intoxication by Stryphnodendron rotundifolium

An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication.     

Fabrication and characterization of a PbTe quantum dots multilayer structure

Multilayer PbTe quantum dots (QDs) and SiO₂ were grown by pulsed laser deposition (PLD) and Plasma enhanced chemical vapor deposition (PECVD) techniques. The crystalline structure, QD size and size dispersion were observed by high-resolution transmission electron microscopy (HRTEM) measurements. This technique allows one to grow PbTe QDs as small as 1.8 nm diameter and 0.6 nm size dispersion. The whole structure can be used in a Fabry–Perot cavity for an optical device operating at the mid-infrared region.     

Preparation and properties of homogeneous V2O5-SiO2 xerogel composite based on interpenetrating polymer network

In this paper, we report the conducting and electrochemical properties of a homogeneous V₂O₅-SiO₂ xerogel composite obtained from the simultaneous polymerization in both inorganic components (Si-O and V-O based polymers) forming an interpenetrating polymer network, where a mutual “solubility” due to cross-links and entanglements was observed. The presence of V₂O₅ inside the silica matrix has a strong effect on electrical conductivity; measurements showed room temperature conductivity almost 1000 times higher than what is found in the literature. In addition, the electrochemical behavior is quite similar to that found in V₂O₅ xerogel. Moreover, the effects of thermal treatment on the conducting and electrochemical properties were investigated. It was found that both properties were improved with no significant effect on V₂O₅ xerogel layered structure.     

Production and characterization of refractive index gratings in high-birefringence fibre optics

In this work, we report production and modelling of both Bragg gratings and rocking filters in high birefringence fibre optics. Bragg gratings are produced by UV (257.0 nm) external interferometric exposition of a frequency-doubled Ar⁺ ion laser, whereas for rocking filters formation the visible Ar⁺ ion laser lines in 488.0 and 514.5 nm are used in an internal method. The spectral characteristics due to the birefringence properties are studied through numerical methods and experimental techniques. The spectral responsivity of the structures under temperature changes and stress application is presented.     

Application of quantum-chemical methods including density functional theory for the interpretation of isotropic hyperfine data. The example of azulenebenzoquinone

The radical anion of aceneazulenedione in which a benzoquinone is fused to an azulene moiety was generated by electrolysis and by reduction with the alkali metals in ethereal solvents. The hyperfine data could not be reproduced by standard Hückel calculations which usually give reliable predictions for the spin distribution in radical ions such as azulene quinones and a variety of extended π systems. However, PPP and, preferably,ab initio geometry optimisations followed by single-point calculations of the Fermi contact interaction with density functional theory, led to a straightforward assignment of the hyperfine coupling constants.     

Thermal and mechanical properties of PE/organoclay nanocomposites

Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The clay was organically modified with four different types of quaternary ammonium salts. The objective of this work is to study the use of montmorillonite clay in the production of nanocomposites by means on rheological, mechanical and crystallization properties of nanocomposites and to compare to the properties of the matrix and PE/unmodified clay nanocomposites. In general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. Apparently, the mixture with Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay.     

Prediction of electrophoretic mobilities in non-aqueous capillary electrophoresis. Optimal separation of quinolones in acetonitrile-water media

A model of electrophoretic behaviour is used to predict the optimum conditions for the separation of a series of quinolones zwitterionic substances in mixtures of acetonitrile-water up to 30% (w/w) of acetonitrile. The effect of pH, pKa, the electrophoretic mobility of protonated and anionic species, and activity coefficients on the electrophoretic behaviour of quinolones is considered. The model proposed allows the resolution between substances in acetonitrile-water mixtures to be predicted from a few experimental data and thus permits one to obtain the best experimental conditions for separation methodologies.     

pKa values of peptides in aqueous and aqueous-organic media. Prediction of chromatographic and electrophoretic behaviour

In the present work, models describing the effect of the pH on the chromatographic and electrophoretic behaviour for polyprotic peptides were compared. The proposed models can be simultaneously used for determination of dissociation constants and selection of the optimum pH for the separation of peptides, in water and acetonitrile-water mixtures widely used in liquid chromatography and in capillary electrophoresis. The models use the pH value measured in the acetonitrile-water mixture instead of the pH value in water and take into account the effect of the activity coefficients. They permit the determination of the acidity constants in the aqueous and hydro-organic mobile phase from chromatographic retention and electrophoretic migration measurements, respectively. The values obtained by both proposed techniques agree with the potentiometric values previously determined. The suitability of the proposed models for predicting chromatographic and electrophoretic behaviour of compounds studied from a limited number of experimental data was also compared. The separation between solutes by both techniques in a complex mixture can be easily predicted, making simple and rapid pH selection to achieve optimum separation.     

A simulation model of a high-capacity methane adsorptive storage system

A two-dimensional model is developed to describe the hydrodynamics, heat transfer and adsorption phenomena associated with the adsorptive storage of natural gas (NG) in cylindrical reservoirs. Intraparticle and film resistances to both heat and mass transfer are neglected. In the momentum equation, Ergun's law is considered locally valid and is extended to two dimensions. These assumptions are fully justified in the paper. Numerical results are presented concerning the pressurization and blowdown of an ultra-lightweight 50 litre cylinder, commercially available for the storage of compressed NG, if it were filled with an activated carbon having a good adsorptive storage capacity. A simple formula is also proposed to predict the filling times for fast charges. The predicted temperature changes in the packed-bed are in good agreement with those reported in the literature for an experimental charge/discharge.