Polymeric foams as the matrix of voltammetric sensors for the detection of catechol, hydroquinone, and their mixtures

Producción CientíficaPorous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16

Reseña: El jurista (Diego Antonio Navarro)

“El Jurista” es una obra escrita por la Doctora María Isabel Lorca Martin de Villodres quien retoma la biografía de Don Diego Antonio Navarro Martín de Villodres 1759-1832), religioso perteneciente a la última monarquía de España en Latinoamérica, para llevar a cabo un cuidadoso estudio de tipo histórico y jurídico en el que resalta el papel desempeñado por el prelado en su paso por América del Sur, dentro de un marco de tiempo transcurrido desde la Ilustración europea hasta la reconquista española del territorio americano

Electroencephalography in consumer behaviour and marketing: a science mapping approach

[EN] Since its inception, the field of consumer neuroscience and neuromarketing has undergone significant development. The principal objective of this work is to identify current research and to define emerging topics in both consumer neuroscience and neuromarketing using electroencephalography (EEG) since no studies have thus far examined this issue. To this end, a bibliometric analysis was conducted with the Science Mapping Software tool SciMAT. In total, 497 articles published between 2002 and 2022 were examined. The analysis encompassed all research from brain regions, technologies, and marketing which can be applied for a better understanding of consumer behaviour. The main contribution of this work is the comprehensive and objective review of the topic, which highlights the potential interest in applying EEG to emerging technologies (e.g., augmented reality, mixed reality, or virtual reality), tourism marketing communications, healthy food products, consumer willingness-topay, service marketing, dynamic stimuli, and consumers’ emotions.S

Operadores económicos autorizados ¿reemplazo, homologación o transformación de las agencias de aduanas?

Este ensayo sobre el Operador Económico Autorizado (OEA) muestra la aplicabilidad e importancia de esta figura en el contexto nacional e internacional. Asimismo se expresa el efecto sobre cada uno de los agentes de la cadena logística del comercio internacional a través de la experiencia recopilada de algunos países y haciendo un breve recuento de aquellos que presentan sistemas especiales en su aplicabilidad, dejando ver características como la flexibilidad en sus marcos normativos y gubernamentales. Se constata cómo este mecanismo es coherente con las intenciones del gobierno colombiano referente a la reducción de trámites, aumento de seguridad y la agilización de procesos. De igual forma se exponen las ventajas indirectas tales como reducción de robos, de pérdidas, de acciones delictivas y de vandalismo a lo largo de las operaciones de comercio internacional. A su vez el OEA permite una mejor planificación, mayor fidelidad de los clientes e implicación del personal con la empresa, así como un mejor seguimiento a la carga. Una de las mayores fortalezas del OEA es el reconocimiento mutuo entre los países ya que se evita la duplicidad de los procesos tanto en origen como de destino.This essay expounds how the Authorized Economic Operator could be applied and the impact of the AEO on the international and local field. At the same time, it presents the effects and consequences over the actors who are involved in the logistics chain of the international trade. Throughout the experience of some countries and looking back to that ones which have special demands for applying the rules and regulations, it can be realized about a main characteristic of AEO which is the flexibility. Then this figure is coherent and has to do with the Colombian government intentions related to procedures reduction, security and procedures speeding up. Besides this essay shows the indirect advantages of adopting AEO such as thefts, losses, accidents and delays reduction. Vandalism and criminal actions can be reduced by applying the AEO guidelines. Moreover the AEO agent could make better business planning which might cause a positive effect on the customer satisfaction. The human capital will be more involved on the company operations and it can feel safer and protected because of AEO. Shipments tracking can be also improved, so the customer would be advised about the freight s status. Undoubtedly the main advantage of AEO is the mutual recognition, so procedure requirements can be reduced by standardizing the origin and destination demands

Characterization of porous nickel-free austenitic stainless steel prepared by mechanical alloying

Nickel-free austenitic powder metallurgy stainless steels were prepared and characterized. The main issue was to obtain potential biocompatible materials. Mechanical alloying in a nitrogen atmosphere was used to obtain these powders. The main factor to be controlled was the milling time. Powder metallurgy was the technique to obtain massive samples from alloyed powders. Two sintering processes were applied by controlling the sinter-cooling rate (furnace and water-cooling). The sintering atmosphere applied was nitrogen because of its gammagenic effect. Samples made of powders milled for 48 h, sintered in nitrogen and water-cooled showed a clean austenitic microstructure, which is a suitable microstructure for biological applications. A complete microstructural characterization, including optical metallography, image analysis, Scanning Electron Microscopy with X-ray microanalysis, X-Ray diffraction and Vickers hardness and microhardness, was carried out. The electrochemical behaviour in a simulated body fluid, phosphate buffered saline, was also studied. The biocorrosion behaviour was evaluated in terms of anodic polarization measurements.2020-07-102020-07-1

Corrosion properties of a low-nickel austenitic porous stainless steel in simulated body fluids

Producción CientíficaNickel can cause severe allergic reactions. Therefore, efforts are made to reduce the content of nickel in austenitic stainless steels (SS). Powder metallurgy (PM) techniques can produce this steel in a highly affordable way. A novel low-nickel high-nitrogen austenitic powder metallurgy PM stainless steel is investigated in terms of corrosion behavior. Nitrogen, because of its gammagenic effect, is the applied sintering atmosphere. Two sintering processes are applied by controlling the sinter-cooling rate (furnace- and water-cooling). This material shows an austenitic microstructure free of precipitates only after the water-cooling process. The electrochemical behavior in two simulated body fluids—phosphate buffered saline (PBS) solution and Ringer solution—are studied. Corrosion behavior is evaluated by means of anodic polarization measurements and cyclic polarization curves. In addition, Electrochemical Impedance Spectroscopy is used to evaluate the corrosion resistance of this steel in PBS at open circuit potential and at 100 mV above corrosion potential. The water-cooling process promotes better corrosion behavior in simulated body fluids for high nitrogen and low nickel than a conventional (high nickel) austenitic PM SS 316LN type

Charge Photoinjection in Intercalated and Covalently Bound [Re(CO)_(3)(dppz)(py)]^(+)–DNA Constructs Monitored by Time-Resolved Visible and Infrared Spectroscopy

The complex [Re(CO)_(3)(dppz)(py′-OR)]+ (dppz = dipyrido[3,2-a:2′,3′-c]phenazine; py′-OR = 4-functionalized pyridine) offers IR sensitivity and can oxidize DNA directly from the excited state, making it a promising probe for the study of DNA-mediated charge transport (CT). The behavior of several covalent and noncovalent Re–DNA constructs was monitored by time-resolved IR (TRIR) and UV/visible spectroscopies, as well as biochemical methods, confirming the long-range oxidation of DNA by the excited complex. Optical excitation of the complex leads to population of MLCT and at least two distinct intraligand states. Experimental observations that are consistent with charge injection from these excited states include similarity between long-time TRIR spectra and the reduced state spectrum observed by spectroelectrochemistry, the appearance of a guanine radical signal in TRIR spectra, and the eventual formation of permanent guanine oxidation products. The majority of reactivity occurs on the ultrafast time scale, although processes dependent on slower conformational motions of DNA, such as the accumulation of oxidative damage at guanine, are also observed. The ability to measure events on such disparate time scales, its superior selectivity in comparison to other spectroscopic techniques, and the ability to simultaneously monitor carbonyl ligand and DNA IR absorption bands make TRIR a valuable tool for the study of CT in DNA

Corneal surface wettability and tear film stability before and after scleral lens wear

Purpose: The aim of this study was to evaluate the anterior surface of scleral contact lens and ocular surface wettability before and after one-month of scleral lens wear in patients with keratoconus. Methods: Forty-nine patients with keratoconus (36.26 ± 9.03 years) were recruited. The sample was divided into two groups: patients with intrastromal corneal ring (KCICRS group) and patients without ICRS (KC group). TFSQ, Schirmer I test, Ocular Surface Disease Index (OSDI questionnaire), tear break-up time (TBUT) and corneal staining were evaluated in two different visits: Baseline (before lens wear) and one-month visit (10 min after lens removal). Visual Analog Scale (VAS questionnaire) was filled in just after inserting the lenses and just before removing them. TFSQ mean and inferior were evaluated over the contact lens surface at the moment of inserting the lens (baseline visit) and after 8 h of lens wear (one-month visit). Results: Anterior corneal surface TFSQ values increased in all groups after scleral lens wear (p  0.05). No changes were found in tear volume for total and in KC and KCICRS groups (p > 0.05). For all groups, there was a statistical decrease of TBUT (p < 0.05). In addition, OSDI score, corneal staining and VAS score improved after scleral lens wear from baseline in total and in both KC and KCICRS groups (p < 0.05). Conclusion: The scleral contact lens surface keeps its wettability after one-month of wear. However, the wettability of the ocular surface is worse after contact lens wearing

Monitoring the phenolic ripening of red grapes using a multisensor system based on metal-oxide nanoparticles

Producción CientíficaThe maturity of grapes is usually monitored by means of the sugar concentration. However, the assessment of other parameters such as the phenolic content is also important because the phenolic maturity has an important impact on the organoleptic characteristics of wines. In this work, voltammetric sensors able to detect phenols in red grapes have been developed. They are based on metal oxide nanoparticles (CeO2, NiO, and TiO2,) whose excellent electrocatalytic properties toward phenols allows obtaining sensors with detection limits in the range of 10−8 M and coefficients of variation lower than 7%. An electronic tongue constructed using a combination of the nanoparticle-based sensors is capable to monitor the phenolic maturity of red grapes from véraison to maturity. Principal Component Analysis (PCA) can be successfully used to discriminate samples according to the ripeness. Regression models performed using Partial Least Squares (PLS-1) have established good correlations between voltammetric data obtained with the electrochemical sensors and the Total Polyphenolic Index, the Brix degree and the Total Acidity, with correlation coefficients close to 1 and low number of latent variables. An advantage of this system is that the electronic tongue can be used for the simultaneous assessment of these three parameters which are the main factors used to monitor the maturity of grapes. Thus the electronic tongue based on metal oxide nanoparticles can be a valuable tool to monitor ripeness. These results demonstrate the exciting possible applications of metal oxide nanoparticles in the field of electronic tongues.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482- R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA011U16)Junta de Castilla y León (grant BOCYL-D-24112015-9