Comparative study of the photodeposition of Pt, Au and Pd on pre-sulphated TiO2 for the photocatalytic decomposition of phenol

A comparative study of the photodeposition of Pt, Au and Pd under the same experimental conditions onto pre-sulphated and non-sulphated TiO2 was performed. Morphological and surface characterisation of the samples as well as photocatalytic activity for phenol photooxidation was studied. The influence of sulphate pre-treatment on the deposits size and dispersion onto the TiO 2 surface, and photodeposition yields with the different metals were also analysed. The photocatalytic activity of the doped materials was then investigated, observing that catalytic behaviour can be correlated to physical characteristics of the samples determined by (XRD) X-ray diffraction, (XPS) X-ray photoelectron spectroscopy, (XRF) X-ray fluorescence spectrometry and (TEM) transmission electron microscopy. Sulphate pre-treatment was found to influence both the level of dispersion and the size of metal clusters on the TiO2 surface. Sulphation and metallisation of samples was found to produce a synergistic enhancement in photoactivity for the degradation of phenol. The photoactivity of the catalysts with respect to the doped metal species was ordered Pt > Pd > Au.Ministerio de Ciencia e Innovación CTQ2008-05961-CO2-01Junta de Andalucía P06-FQM-140

The implementation of free software in firms, an empirical analysis

This article presents the findings of a research aimed at characterizing open source migration initiatives. Thirty experiences have been considered in total, ninety of them are Public Administrations and the rest are private firms, operating different industries in eight different countries. Open source migration projects have become a recent research topic, especially from the managerial perspective. To overcome the lack of theoretical models, an empirical approach relying on grounded theory has been adopted. This inductive approach allows theory building and hypothesis formulation. According to the results, migrating from proprietary into open source is dependent on contextual and organizational factors, as for example, the need of the change itself, the political support for the change, the access to IT resources, the organizational climate, the motivation of the human resources, and the leadership style for the project or the firm complexity. Besides, migration efforts imply strategic and organizational consequences that the organization must properly evaluate beforehand

Teaching experiment about Dynamics I (Newton’s laws): a theoretical-practical innovative proposal

Se describe aquí una propuesta de ciclo de mejora en el aula para la asignatura de Física I de primer curso del Grado en Ingeniería Química Industrial de la Universidad de Sevilla, centrado en la docencia del tema de Dinámica I: Leyes de Newton. El trabajo en el diseño de contenidos, tareas metodológicas y herramientas de evaluación del nivel de aprendizaje alcanzado se ha inspirado en la aplicación del método científico-deductivo, basado en pautas de investigación docente. Para ello se ha intentado involucrar activamente al alumnado haciéndolo consciente de sus ideas previas y enfrentándolo a actividades de contraste antes y después de recibir información en el formato típico de lección magistral, cuya frecuencia se ha pretendido minimizar. Además, se han incorporado al ciclo de mejora las sesiones prácticas de laboratorio, que se integran temporalmente con las de teoría intentando coordinar y armonizar la metodología.A proposal for a teaching improvement cycle is described here for the Physics I subject of the first course of the Degree in Industrial Chemical Engineering at the University of Seville, focused on the Dynamics I: Newton’s laws subject. Work on the design of contents, methodological tasks and evaluation tools of the achieved learning level has been inspired by the application of the scientific-deductive method, based on teaching research guidelines. For this purpose, an attempt has been made to actively involve the students, making them aware of their previous ideas and confronting them with contrasting activities before and after receiving information in the typical lecture format, the frequency of which has been tried to minimize. In addition, practical laboratory sessions have been incorporated into the cycle, which are temporarily integrated with the theory ones trying to coordinate and harmonize the methodology

THE POTENTIAL OF NEAR INFRARED SPECTROSCOPY AS A METHOD OF DETERMINATION OF THE FAT CONTENT IN

Yogurt is a food product produced by fresh milk as the raw material which is easier to digest and assimilate than fresh milk. Today, it is a very popular food product and is marketed worldwide.Consequently, is important to know its chemical composition. On the other hand, the use of near-infrared technologies is increasing in the last years as it is a fast and easy technique.Nevertheless, studies about its use in yogurts are limited. 141 samples of yogurt were analysed by NIRS. The whole experiment was carried out at 20ºC. 75% of the samples were used for calibration set and the rest were used for validating this model. A NIR Luminar 5030 Miniature “Hand-held” with a spectral range of 1100-2300 nm was used to obtain the spectra, with a sampling interval of 2 nm. The software used for analysis was The Unscrambler. The predictive models were established by using partial least squares (PLS). The information that is used to predict the composition and quantities of the samples is contained into the spectral curves. The pivotal step for spectroscopy technique is to extract quantitative data from them. In this study, PLS algorithm was used to achieve this purpose. 87 samples were chosen as a calibration sample cluster, and PLS mathematic model was built by using NIR-spectroscopy and fat content of each sample (Fig.1). The correlation coefficient between spectral data and fat content of yogurt was 0.965, the standard error of calibration (SEC) was 0.587, and the standard error of prediction (SEP) was 0.642. The fat content of another 33 samples was predicted by a mathematical model (Fig.2). The correlation coefficient of linear regression between predicted and measured values shows a reasonable to excellent prediction performance of 0.929. In conclusion, the results indicated that NIRS could quantitatively analyze fat content of yogurt in a fast and non-destructive way

Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds

Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.España FEDER y MINECO MINECO (projects MAT2013-40852-R, MAT2016-79866-R, MINECOCSIC 201560E055)España, RECUPERA 2020 y Junta de Andalucía project P12-2265 M

Interplay between symmetry and spin-orbit coupling on graphene nanoribbons

We study the electronic structure of chiral and achiral graphene nanoribbons with symmetric edges, including curvature and spin-orbit effects. Curved ribbons show spin-split bands, whereas flat ribbons present spin-degenerate bands. We show that this effect is due to the breaking of spatial inversion symmetry in curved graphene nanoribbons, while flat ribbons with symmetric edges possess an inversion center, regardless of their having chiral or achiral edges. We find an enhanced edge-edge coupling and a substantial gap in narrow chiral nanoribbons, which is not present in zigzag ribbons of similar width. We attribute these size effects to the mixing of the sublattices imposed by the edge geometry, yielding a behavior of chiral ribbons that is distinct from those with pure zigzag edges. © 2013 American Physical Society.This work has been partially supported by the Spanish Ministries of Science and Innovation (MICINN) and Economy and Competitivity (MINECO) DGES under Grants No. MAT2009-14578-C03-03, No. PIB2010BZ-00512, No. FIS2010-21282-C02-02, No. FIS2011-23713, No.MAT2012-38045-C04-04, and No. FIS2012-33521.Peer Reviewe

Análisis de localización para la instalación de una central de aprovechamiento de energía undimotriz en la costa norte de España

Numerosos estudios han revelado que existe un gran potencial energético en la costa norte de la Península Ibérica gracias a que el Océano Atlántico baña este territorio. Con el desarrollo e investigación de nuevas tecnologías, se plantea la posibilidad de construir una central de aprovechamiento undimotriz, que esté integrada en uno de los diques de mayor entidad en el norte de España, como son el dique de Punta Langosteira (Puerto Exterior de A Coruña, Galicia), el dique de Torres y Norte (Ampliación del Puerto de Gijón, Asturias) y el dique de Punta Lucero (Puerto de Bilbao, País Vasco)

Improved wear performance of ultra high molecular weight polyethylene coated with hydrogenated diamond like carbon

Hydrogenated diamond like carbon (DLCH) thin films were deposited on medical grade ultra high molecular weight polyethylene (UHMWPE) by radio frequency plasma enhanced chemical vapor deposition. The DLCH coating thicknesses ranged from 250 to 700. nm. The substrates were disks made of UHMWPEs typically used for soft components in artificial joints, namely virgin GUR 1050 and highly crosslinked (gamma irradiated in air to 100. kGy) UHMWPEs. Mechanical and tribological properties under bovine serum lubrication at body temperature were assessed on coated and uncoated polyethylenes by means of nano-hardness and ball-on-disk tests, respectively. Morphological features of the worn surfaces were obtained by confocal microscopy and scanning electron microscopy. This study confirms an increase in surface hardness and good wear resistance for coated materials after 24. h of sliding test compared to uncoated polyethylene. These results point out that to coat UHMWPE with DLCH films could be a potential method to reduce backside wear in total hip and knee arthroplasties.Ministerio de Ciencia y Educación MAT2006-12603- C02-01, CSD2008-0002

Influence of Titanium Oxide Pillar Array Nanometric Structures and Ultraviolet Irradiation on the Properties of the Surface of Dental Implants: A Pilot Study

Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current research is focusing on the improvement of the chemical and physical properties of their surfaces in order to improve the osseointegration process. TiO2, when it is deposited in the form of pillar array nanometric structures, has photocatalytic properties and wet surface control, which, together with UV irradiation, provide it with superhydrophilic surfaces, which may be of interest for improving cell adhesion on the peri-implant surface. In this article, we address the influence of this type of surface treatment on type IV and type V titanium discs on their surface energy and cell growth on them. Materials and methods: Samples from titanium rods used for making dental implants were used. There were two types of samples: grade IV and grade V. In turn, within each grade, two types of samples were differentiated: untreated and treated with sand blasting and subjected to double acid etching. Synthesis of the film consisting of titanium oxide pillar array structures was carried out using plasma-enhanced chemical vapor deposition equipment. The plasma was generated in a quartz vessel by an external SLAN-1 microwave source with a frequency of 2.45 GHz. Five specimens from each group were used (40 discs in total). On the surfaces to be studied, the following determinations were carried out: (a) X-ray photoelectron spectroscopy, (b) scanning electron microscopy, (c) energy dispersive X-ray spectroscopy, (d) profilometry, (e) contact angle measurement or surface wettability, (f) progression of contact angle on applying ultraviolet irradiation, and (g) a biocompatibility test and cytotoxicity with cell cultures. Results: The application of ultraviolet light decreased the hydrophobicity of all the surfaces studied, although it did so to a greater extent on the surfaces with the studied modification applied, this being more evident in samples manufactured in grade V titanium. In samples made in grade IV titanium, this difference was less evident, and even in the sample manufactured with grade IV and SLA treatment, the application of the nanometric modification of the surface made the surface optically less active. Regarding cell growth, all the surfaces studied, grouped in relation to the presence or not of the nanometric treatment, showed similar growth. Conclusions. Treatment of titanium oxide surfaces with ultraviolet irradiation made them change temporarily into superhydrophilic ones, which confirms that their biocompatibility could be improved in this way, or at least be maintained

Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review

Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of the application of CAs to enhance the Fenton process for the remediation of soils polluted with the most common organic contaminants, especially for a deep understanding of the activation mechanisms and influential factors. The existing shortcomings and research needs have been highlighted. Finally, future research perspectives on the use of CAs in MF and recommendations have been provided.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEComunidad de MadridMinisterio de Cienciapu