Specific and reversible immobilization of proteins tagged to the affinity polypeptide C-LytA on functionalized graphite electrodes

We have developed a general method for the specific and reversible immobilization of proteins fused to the choline-binding module C-LytA on functionalized graphite electrodes. Graphite electrode surfaces were modified by diazonium chemistry to introduce carboxylic groups that were subsequently used to anchor mixed self-assembled monolayers consisting of N,N-diethylethylenediamine groups, acting as choline analogs, and ethanolamine groups as spacers. The ability of the prepared electrodes to specifically bind C-LytA-tagged recombinant proteins was tested with a C-LytA-β-galactosidase fusion protein. The binding, activity and stability of the immobilized protein was evaluated by electrochemically monitoring the formation of an electroactive product in the enzymatic hydrolysis of the synthetic substrate 4-aminophenyl β-D-galactopyranoside. The hybrid protein was immobilized in an specific and reversible way, while retaining the catalytic activity. Moreover, these functionalized electrodes were shown to be highly stable and reusable. The method developed here can be envisaged as a general, immobilization procedure on the protein biosensor field.

Spectroelectrochemical Study of the Photoinduced Catalytic Formation of 4,4′-Dimercaptoazobenzene from 4-Aminobenzenethiol Adsorbed on Nanostructured Copper

Surface-enhanced raman scattering (SERS) spectra of self-assembled monolayers of 4-aminobenzenethiol (4-ABT) on copper (Cu) and silver (Ag) surfaces decorated with Cu and Ag nanostructures, respectively, have been obtained with lasers at 532, 632.8, 785, and 1064 nm. Density functional theory (DFT) has been used to obtain calculated vibrational frequencies of the 4-ABT and 4,4′-dimercaptoazobenzene (4,4′-DMAB) molecules adsorbed on model Cu surfaces. The features of the SERS spectra depend on the electrode potential and the type and power density of the laser. SERS spectra showed the formation of the 4,4′-DMAB on the nanostructured Cu surface independently of the laser employed. For the sake of comparison SERS spectra of a self-assembled monolayer of the 4-ABT on Ag surfaces decorated with Ag nanostructures have been also obtained with the same four lasers. When using the 532 and 632.8 nm lasers, the 4,4′-DMAB is formed on Cu surface at electrode potentials as low as −1.0 V (AgCl/Ag) showing a different behavior with respect to Ag (and others metals such as Au and Pt). On the other hand, the surface-enhanced infrared reflection absorption (SEIRA) spectra showed that in the absence of the laser excitation the 4,4′-DMAB is not produced from the adsorbed 4-ABT on nanostructured Cu in the whole range of potentials studied. These results point out the prevalence of the role of electron–hole pairs through surface plasmon activity to explain the obtained SERS spectra.

Influence of alkylphosphonic acid grafting on the electronic and magnetic properties of La2/3Sr1/3MnO3 surfaces

Self-assembled monolayers (SAMs) are highly promising materials for molecular engineering of electronic and spintronics devices thanks to their surface functionalization properties. In this direction, alkylphosphonic acids have been used to functionalize the most common ferromagnetic electrode in organic spintronics: La2/3Sr1/3MnO3 (LSMO). However, a study on the influence of SAMs grafting on LSMO electronic and magnetic properties is still missing. In this letter, we probe the influence of alkylphosphonic acids-based SAMs on the electronic and magnetic properties of the LSMO surface using different spectroscopies. We observe by X-ray photoemission and X-ray absorption that the grafting of the molecules on the LSMO surface induces a reduction of the Mn oxidation state. Ultraviolet photoelectron spectroscopy measurements also show that the LSMO work function can be modified by surface dipoles opening the door to both tune the charge and spin injection efficiencies in organic devices such as organic light-emitting diodes.

An explanatory model of academic achievement based on aptitudes, goal orientations, self-concept and learning strategies

As a result of studies examining factors involved in the learning process, various structural models have been developed to explain the direct and indirect effects that occur between the variables in these models. The objective was to evaluate a structural model of cognitive and motivational variables predicting academic achievement, including general intelligence, academic self-concept, goal orientations, effort and learning strategies. The sample comprised of 341 Spanish students in the first year of compulsory secondary education. Different tests and questionnaires were used to evaluate each variable, and Structural Equation Modelling (SEM) was applied to contrast the relationships of the initial model. The model proposed had a satisfactory fit, and all the hypothesised relationships were significant. General intelligence was the variable most able to explain academic achievement. Also important was the direct influence of academic self-concept on achievement, goal orientations and effort, as well as the mediating ability of effort and learning strategies between academic goals and final achievement.

Probing the Electrocatalytic Oxygen Reduction Reaction Reactivity of Immobilized Multicopper Oxidase CueO

The bioelectrocatalytic (oxygen reduction reaction, ORR) properties of the multicopper oxidase CueO immobilized on gold electrodes were investigated. Macroscopic electrochemical techniques were combined with in situ scanning tunneling microscopy (STM) and surface-enhanced Raman spectroscopy at the ensemble and at the single-molecule level. Self-assembled monolayer of mercaptopropionic acid, cysteamine, and p-aminothiophenol were chosen as redox mediators. The highest ORR activity was observed for the protein attached to amino-terminated adlayers. In situ STM experiments revealed that the presence of oxygen causes distinct structure and electronic changes in the metallic centers of the enzyme, which determine the rate of intramolecular electron transfer and, consequently, affect the rate of electron tunneling through the protein. Complementary Raman spectroscopy experiments provided access for monitoring structural changes in the redox state of the type 1 copper center of the immobilized enzyme during the CueO-catalyzed oxygen reduction cycle. These results unequivocally demonstrate the existence of a direct electronic communication between the electrode substrate and the type 1 copper center.

A structural model of cognitive-motivational variables as explanatory factors of academic achievement in Spanish Language and Mathematics

In recent years, several explanatory models have been developed which attempt to analyse the predictive worth of various factors in relation to academic achievement, as well as the direct and indirect effects that they produce. The aim of this study was to examine a structural model incorporating various cognitive and motivational variables which influence student achievement in the two basic core skills in the Spanish curriculum: Spanish Language and Mathematics. These variables included differential aptitudes, specific self-concept, goal orientations, effort and learning strategies. The sample comprised 341 Spanish students in their first year of Compulsory Secondary Education. Various tests and questionnaires were used to assess each student, and Structural Equation Modelling (SEM) was employed to study the relationships in the initial model. The proposed model obtained a satisfactory fit for the two subjects studied, and all the relationships hypothesised were significant. The variable with the most explanatory power regarding academic achievement was mathematical and verbal aptitude. Also notable was the direct influence of specific self-concept on achievement, goal-orientation and effort, as was the mediatory effect that effort and learning strategies had between academic goals and final achievement.

Capacidad predictiva de la autoeficacia académica sobre las dimensiones del autoconcepto en una muestra de adolescentes chilenos

El objetivo de este estudio fue analizar la capacidad predictiva de la autoeficacia académica sobre las dimensiones del autoconcepto en una muestra de 860 estudiantes chilenos. El análisis de regresión logística reveló que la autoeficacia académica fue un predictor positivo y significativo de las escalas académicas (Matemáticas, Verbal y Académica General), no académicas (Habilidades Físicas, Apariencia Física, Relaciones con el Sexo Opuesto, Relaciones con el Mismo Sexo, Relación con los Padres, Sinceridad- Veracidad), y de la escala de Autoestima, excepto de la escala de Estabilidad Emocional. Esta relación de predicción fue de mayor magnitud con las escalas académicas y autoestima.

Technologies for Seduction: The “Espacio Doméstico” VideoArt Center in Blanca [EDOM]

Sustainability, understood in its beginnings as a common horizon for multiple practices and fields of study, has gradually given way to the development of increasingly sophisticated tools, with distinct dominant meanings established for each discipline. Within the field of material technologies for architectural production, sustainability seems to have found its most fertile ground in topics such as recycling, the use of "bio" materials, or energetic efficiency. However, to improve the understanding of the impact of technology on our ways of living, it appears increasingly necessary to move from the deterministic logic of sustainability into the relational domain of ecology, where the use and deployment of technologies can be observed through the multiplicity of its effects and the diversity of actors involved. In this paper we will address the case of the rehabilitation of several traditional houses located in the Murcian town of Blanca to host the “Espacio Doméstico” VideoArt Center (EDOM). In this action the selection and implementation of technologies have been aimed at impacting on diverse aspects including local communities, digital manufacturing, recycling, and policies regarding the rehabilitation of heritage buildings. While the initial approach was to address housing recovery as a heterogeneous accumulation of stories, technologies or material deployments of the domestic, our intervention strategies ascribed to the different technologies the role of mediating with existing elements through the incorporation of the very different visions of sustainability. Thus, we displayed artifacts produced by digitally manufactured methacrylate assembled on IKEA structures, fluorescent power lines supported by insulators on the wall, fluorescent tattoos on walls and ceilings that guide and extend the configuration of existing flooring, esparto furniture and fabrics produced by the esparto women workers’ and village women’s associations, re-appropriations of old furniture through the implementation of new media technologies, etc. If we can see seduction as the process of converting affinities and disagreements into affirmative communication, then the EDOM proposal can be seen as an active seduction process between technologies and users who approach this kind of cultural artifacts. Through these permanently active processes, art technologies will refer the viewer to complex sensory experiences, where a combination of parody, memory and sound pushes the user to the limit of mere comprehension of works of art. This more relational approach to the issue of heritage rehabilitation, technology or art institutions is offered as an area of controversy and debate on the scope of political ecology and its potential impact on the architect’s professional practice.

¿Predice la autoeficacia percibida la ansiedad escolar? Estudio con estudiantes chilenos de Educación Secundaria

Dada la importancia de las creencias de eficacia personal en el desarrollo cognitivo de las personas y su marcada influencia en las reacciones emocionales y conductuales experimentadas sobre todo ante situaciones difíciles, el objetivo de este estudio es analizar la capacidad predictiva de la autoeficacia percibida sobre la ansiedad escolar en una muestra de 1284 estudiantes chilenos de educación secundaria, 634 chicos y 650 chicas (49.4% y 50.6% respectivamente) con edades entre los 14 y 18 años (M = 15.43, DE = 1.24). Para ello, se evaluó la autoeficacia percibida con la Escala de Autoeficacia Percibida Específica de Situaciones Académicas (EAPESA) y la ansiedad escolar con el Inventario de Ansiedad Escolar (IAES). Los análisis de regresión logística revelaron que bajas puntuaciones en autoeficacia académica percibida predicen la alta ansiedad, revelando con ello la influencia de la autoeficacia percibida sobre la ansiedad escolar. A partir de estos resultados, es posible anticipar que la mejora de las expectativas de autoeficacia aumentaría las probabilidades de disminuir los elevados niveles de ansiedad en los estudiantes.