Authenticity Control of Roasted Coffee Brands Using Near-Infrared Spectroscopy

In this work, a methodology based on near-infrared spectroscopy (NIRS) was exploited in order to discriminate between commercial coffee brands. The main advantages of this approach compared to other strategies (e.g., wet chemistry methods) are its lower cost, less labor, and lower time per analysis. Two commercial brands were discriminated among several others present in the Portuguese market. The chemometric method used to estimate discriminant models was partial least squares discriminant analysis (PLSDA). Results show that it is possible to discriminate coffee brands using this strategy with a correct classification of 100 %. The spectral region, more favorable to discrimination of roasted coffee brands, can be related with differences in the concentrations of compounds, such as, chlorogenic acid and sucrose, and also due to differences on lipid fraction. This methodology is adequate for field implementation, namely, adopting handheld NIRS instruments.     

Electrocatalytic properties of diamond in the oxidation of a persistant pollutant

This work is focused on the study of the role of several conductive-diamond characteristics (boron doping, sp³/sp² ratio, diamond-layer thickness) on the performance of the electrolysis of enrofloxacin (as model complex-organic pollutant). Commercial lots provided by an important conductive-diamond manufacturing company have been used. Results show that enrofloxacin electrooxidation is strongly influenced by the conductive-diamond characteristics; particularly the ratio diamond/graphite carbon was found one of the most significant parameters in this process: the higher the content in diamond-carbon the greater the TOC and COD decays in the bulk electrolyses. These results have been interpreted in terms of the oxidation mechanism involved. High graphite content favours direct oxidation of the pollutant on the electrode surface and leads to the formation of many intermediates. On contrary, high diamond content seems to favour the complete oxidation of the organic to carbon dioxide, thanks to the contribution of the oxidants (hydroxyl radicals and electrogenerated reagents) present in a region close to the electrode surface. Likewise, the oxidation rate seems to be improved with increase in the concentration of boron and decrease in the thickness of the substrate layer.     

Effect of mullite additions on the fracture mode of alumina

This work analyses the effect of mullite additions on the fracture mode of alumina. Mullite is proposed as an alternative to SiC for the second phase particles because the thermal expansion mismatch between alumina and mullite is of the same sign and order as that between alumina and SiC. Three alumina–5 vol.% mullite composites formed by alumina matrices with similar average grain sizes in the micrometric range (≈1 μm) and second phase sub-micrometric (50–350 nm) and nanometric mullite (<50 nm) particles located at grain boundaries and triple points were prepared. The fracture mode of the alumina matrix changed from predominantly intergranular to predominantly transgranular. This change became more significant as the size of the sub-micrometric fraction of mullite particles decreased.     

Design of a soft-error robust microprocessor

The costs to protect a commercial microprocessor against soft errors are discussed in this work. Based on hardware and time redundancies, a protection scheme was designed at RT level to mitigate transient faults on combinational and memory circuits. A fault-tolerant IC version of a mass-produced 8-bit microprocessor is protected by the scheme. Design issues and results in area, performance and power are presented comparing the robust microprocessor with its non-protected version. The costs by flip-flop are also discussed permitting to estimate the overheads in area for any architecture. Furthermore, the RT-level protection scheme is compared with an electrical-level scheme based on a non-standard gate.     

Electrospray ionization mass spectrometry fingerprinting of essential oils: Spices from the Labiatae family

Polar components of the methanolic extracts of the essential oils of the spices Origanum dictamnus, Origanum vulgare, Origanum majorana and Rosmarinus officinalis, all four belonging to the Labiatae family, were investigated by direct infusion electrospray ionisation mass spectrometry (ESI-MS) both in the negative and positive ion modes. Characteristic ESI mass spectra with many diagnostic ions were obtained for the extracts of all four spices, serving for fast and reliable identification of these species. Tandem mass spectrometry (ESI-MS/MS), which often forms a series of fragment ions, and this additional MS dimension increases selectivity for authenticity and adulteration tests for spice essential oils. The MS technique also provides complementary information of component structures revealing the presence of important bioactive components.     

A time temperature integrator for particulated foods: thermal process evaluation

 A time temperature integrator (TTI) was developed by immobilizing Bacillus stearothermophilus spores in a cylindrical particle consisting of an alginate-starch-mushroom purée. The particle showed homogeneous spore distribution, and when heated over a temperature range of 121 – 130° C negligible spore leakage was observed after the thermal process. The experimental data on spore survivor levels obtained for each temperature-time combination were compared with theoretical predictions using a mathematical model. The results showed a good correlation between the experimental and theoretical data. All these results provide evidence that this artificial particle could be a very reliable TTI for monitoring the thermal impact on micro-organisms during validating sterilization processes in continuous aseptic systems. Received: 25 February 1997     

A new methodology for studying the performance of products against ruminal acidosis

This paper describes a new and convenient methodology for studying the performance of products used in the treatment of ruminal acidosis. The method is based on potentiometric titration of the increase in buffer capacity and acid consuming capacity after the addition of products to a suitable medium at physiological rumen pH values. The testing medium is a mixture of buffer substances (phosphate, maleate and volatile fatty acids) that mimics real ruminal fluid in chemical composition, pH and temperature, providing useful experimental results allowing easy testing of antacids. This methodology was applied to the testing of four raw materials (sodium bicarbonate, two calcium carbonates and magnesium oxide). Results in good agreement with theoretical predictions and field experience were obtained. Copyright © 2003 Society of Chemical Industry     

Intrusion Detection System for Wireless Sensor Networks Using Danger Theory Immune-Inspired Techniques

An IDS framework inspired in the Human Immune System to be applied in the wireless sensor network context is proposed. It uses an improved decentralized and customized version of the Dendritic Cell Algorithm, which allows nodes to monitor their neighborhood and collaborate to identify an intruder. The work was implemented and tested both in simulation and in real sensor platform scenarios, comparing them to each other and was also compared to a Negative Selection Theory implementation in order to demonstrate its efficiency in detecting a denial-of-sleep attack and in energy consumption. Results demonstrated the success of the proposal.     

HPLC separation,NMR and QTOF/MS/MS structure elucidation of a prominent nitric oxide donor agent based on an isomeric composition of a nitrosyl ruthenium complex

A new and promising nitrosyl ruthenium complex, [Ru(NO)(bdqi-COOH)(terpy)](PF₆)₃, bdqi-COOH is 3,4-diiminebenzoic acid and terpy is 2,2′-terpyridine, has been synthesized as a NO donor agent. The procedure used for [Ru(NO)(bdqi-COOH)(terpy)](PF₆)₃ synthesis has, apparently, yielded the formation of two isomers in which the ligand bdqi-COOH appears to be coordinated in its reduced form (bdcat-COOH), which could have differences in their pharmacological properties. Therefore, it was intended to separate the two possible isomers by high-performance liquid chromatography (HPLC) and to characterize them by high resolution mass spectrometry (QTOF MS) and by magnetic nuclear resonance spectroscopy (NMR). The results obtained by MS showed that the ESI-MS mass spectra of both HPLC column fractions, e.g. peak 1 and peak 2, are essentially equal, showing that both isomers display nearly identical gas-phase behavior with clusters of isotopologue ions centered at m/z 573, m/z 543 and m/z 513. Regarding the NMR analysis, the results showed that the positional isomerism is located in the bdqi-COOH ligand. From the observed results it can be concluded that the synthesis procedure that has been used results in the formation of two [Ru(terpy)(bdqi-COOH)NO](PF₆)₃ isomers.     

Interparticle Potentials in Nonaqueous Silicon Nitride Suspensions

The rheological properties of nonaqueous silicon nitride suspensions are studied. Suspensions were prepared to volume fractions of solids of 0.21, 0.25, 0.29, and 0.33, and dispersed with phosphate ester in a mixture of solvents (methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone). Expanded viscosity curves were obtained by measuring under controlled rate and stress conditions, and the experimental data were fitted to the Cross model that provides the high shear limiting viscosity (η_∞). The evolution of viscosity with volume fraction of solids was fitted to the Krieger-Dougherty equation, to predict the maximum packing fraction (φ_m). The electrostatic pair potential was calculated based on the DLVO theory by evaluating the dielectric constant of the three-component solvent and the Hamaker constant of the Si₃N₄–solvent system. The surface potential was calculated by measuring the elastic modulus through dynamic rheological measurements. The steric potential was also evaluated from the available models. It has been observed that phosphate ester provides a purely steric stabilization at short separation distances (up to 9 nm), while electrostatic forces dominate at larger separation distances.