Tenderness of PGI "Ternera de Navarra" Beef Samples Determined by FTIR-MIR Spectroscopy.

Understanding meat quality attribute changes during ageing by using non-destructive techniques is an emergent pursuit in the agroindustry research field. Using beef certified samples from the protected geographical indication (PGI) "Ternera de Navarra", the primary goal of this study was to use Fourier transform infrared spectroscopy on the middle infrared region (FTIR-MIR) as a tool for the examination of meat tenderness evolution throughout ageing. Samples of the longissimus dorsi muscle of twenty young bulls were aged for 4, 6, 11, or 18 days at 4 °C. Animal carcass classification and sample proximate analysis were performed to check sample homogeneity. Raw aged steaks were analyzed by FTIR-MIR spectroscopy (4000-400 cm-1) to record the vibrational spectrum. Texture profile analysis was performed using a multiple compression test (compression rates of 20%, 80%, and 100%). Compression values were found to decrease notably between the fourth and sixth day of ageing for the three compression rates studied. This tendency continued until the 18th day for C20. For C80 and C100, there was not a clear change in the 11th and 18th days of the study. Regarding FTIR-MIR as a prediction method, it achieved an R2 lower than 40%. Using principal component analysis (PCA) of the results, the whole spectrum fingerprint was used in the discrimination of the starting and final ageing days with correct maturing time classifications. Combining the PCA treatment together with the discriminant analysis of spectral data allowed us to differentiate the samples between the initial and the final ageing points, but it did not single out the intermediate points.

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption.

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol-gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N2 adsorption-desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n-hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n-hexane increased with the relative response and reached a plateau that stabilized at approximately -31 kJ mol-1 for Ph40 and Ph50 and at approximately -37 kJ mol-1 for Ph30. This indicates that the adsorbate-adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure.

A fiber-optic sensor to detect volatile organic compounds based on a porous silica xerogel film.

Fiber-optic sensors are increasingly used for the determination of volatile organic compounds (VOCs) in air matrices. This paper provides experimental results on the sensitivity of a fiber-optic sensor that uses a film of a porous silica xerogel as the sensing element. This film was synthesized by the sol-gel process and affixed to the end of the optical fiber by the dip-coating technique. This intrinsic sensor works in reflection mode, and the transduction takes place in the light that travels through the core of the fiber. The VOCs included in this research cover a wide range of compounds with different functional groups and polarities. The highest sensitivity was for 2-propanol (13.1±1.4 M(-1) nm(-1)), followed by toluene (11.4±1.4 M(-1) nm(-1)), and 1-butylamine (9.5±0.4 M(-1) nm(-1)). Acetone and cyclohexane had the lowest sensitivity of all studied VOCs. Limits of detection varied between 9.1×10(-5) M for 1-butylamine and 1.6×10(-3) M for ethanol. Silanol groups on the xerogel surface act as weak acids and interact strongly with molecules that contain OH groups like alcohols, π-electrons like toluene, or a lone pair of electrons like toluene. Stronger interaction of methanol and ethanol with the silanol groups on the film led to some irreversible adsorption of these analytes at room temperature.

Characterization of the hydrophobicity of mesoporous silicas and clays with silica pillars by water adsorption and DRIFT.

The hydrophobic-hydrophilic properties of a solid are related to the material chemistry and, often, these properties are relevant to the applications of a particular material. Contrarily to what happens with other properties, such as specific surface areas or pore volumes, the methodologies to ascertain on the hydrophilicity of a porous material are not well defined. In this work, we discuss and relate the information on the hydrophobicity degree obtained from water adsorption isotherms and from diffuse reflectance infrared Fourier transform (DRIFT), in a set of porous materials. The studied materials were mainly mesoporous solids, namely of MCM-41 and SBA-15 types, two xerogels and also different porous clays heterostructures. Both techniques were informative on the hydrophobic-hydrophilic properties of the studied samples, but the correlation between the information obtained by each technique was not straightforward. Water adsorption isotherms are much more sensitive to the differences of the studied materials than the DRIFT spectra. For silica-based mesoporous materials with similar surface chemistry, the water adsorption process and hence, the hydrophobic-hydrophilic properties, is mainly dependent on the pore diameters. However, water adsorption is much more sensitive to changes in the nature of the adsorbent surface than to changes in the pore diameter.

Particle and surface characterization of a natural illite and study of its copper retention.

Illite clays are known to have a strong affinity for metallic pollutants in the environment and can be applied as low-cost adsorbents for industrial waste treatment. A crucial factor in the development of such applications, however, is the understanding of the chemical, mineralogical, and colloidal properties of these clays. It is also important to understand the mechanisms involved in the surface adsorption of metals by these adsorbants. In order to study the retention of transition metals on illite clays, we have applied surface characterization techniques such as FPIA, SEM-EDX, XRD, N2 (77 K) adsorption, and FTIR. In addition to these experimental techniques, we have also employed a theoretical model that accounts for the chemistry of transition metal ions, and considers the global retention process to be the sum of several single retention processes. This model adequately fits the experimental data and allows for the speciation of metal retention on illite surfaces. Between pH values of 2.53 and 3.01 the only adsorption processes are the electrostatic sorption of [Cu(H2O)6]2+, and the surface complexation of [Cu(H2O)6]2+ and [Cu(OH)(H2O)5]+ ions. Surface complexation of [Cu(OH)(H2O)5]+ ions increases with pH, overcoming [Cu(H2O)6]2+ retention, and thus contributing to the surface precipitation of Cu(OH)2.

Bloqueo del plexo braquial con lidocaína más opioides para disminuir el tiempo de latencia / Block of the brachial plexus with lidocaine and fentanyl or bupreorphine to decrease the time of latency

Se estudió el efecto analgésico de la buprenorfina y fentanyl mezclados con lidocaína al 1.5 por ciento en el bloqueo del plexo braquial, en 26 pacientes divididos en tres grupos. El grupo I formado por 5 pacientes, recibió lidocaína al 1.5 por ciento 350 mg; en el grupo II se incluyeron 7 pacientes a quienes se les inyectó lidocaína al 1.5 por ciento 350 mg más 300 µg de buprenorfina; y el grupo III, formado por 14 pacientes recibió lidocaína al 1.5 por ciento 350 mg más 50 µg de fentanyl. El objetivo de agregar un opioide al anestésico local fue disminuir el tiempo de latencia y aumentar la duración del bloqueo sensitivo y motor. La latencia promedio del bloqueo sensitivo total del grupo I fue mayor a la del grupo II (p< 0.001) y III (p< 0.05). El tiempo de latencia promedio del bloqueo motor total del grupo I fue mayor al del grupo II (p< 0.05) y grupo III (p< 0.001). La duración del bloqueo motor total del grupo I fue menor a la del grupo II (p< 0.001) y grupo III (p< 0,05). Por lo tanto se concluye que los opiodes si disminuyen la latencia y aumentan la duración del bloqueo sensitivo y motor cuando se aplican en el plexo braquial