Influence of the strong metal support interaction effect (SMSI) of Pt/TiO2 and Pd/TiO2 systems in the photocatalytic biohydrogen production from glucose solution

Two different catalysts consisting of Pt/TiO2 and Pd/TiO 2 were submitted to diverse oxidative and reductive calcination treatments and tested for photocatalytic reforming of glucose water solution (as a model of biomass component) in H2 production. Oxidation and reduction at 850°C resulted in better photocatalysts for hydrogen production than Degussa P-25 and the ones prepared at 500°C, despite the fact that the former consisted in very low surface area (6-8 m2/g) rutile titania specimens. The platinum-containing systems prepared at 850°C give the most effective catalysts. XPS characterization of the systems showed that thermal treatment at 850°C resulted in electron transfer from titania to metal particles through the so-called strong metal-support interaction (SMSI) effect. Furthermore, the greater the SMSI effect, the better the catalytic performance. Improvement in photocatalytic behavior is explained in terms of avoidance of electron-hole recombination through the electron transfer from titania to metal particles

Intrinsic surface band bending in Cu3 N (100) ultrathin films

8 págs.; 11 figs.; 1 tab. ; PACS number s : 68.55. a, 73.20.At, 61.10. iHighly homogeneous, ultrathin films of copper nitride (Cu3 N) have been grown on Fe(001) at room temperature using a Cu evaporator and a radio-frequency plasma source to obtain atomic nitrogen in a UHV environment. Cu3 N is a semiconductor with the valence band edge at -0.65±0.05 eV below the Fermi Level. The formation of copper nitride can be detected spectroscopically by the shape of the Cu LVV-Auger electron transition, which changes sensibly in shape and position compared to metallic Cu. Cu3 N grows epitaxially with the substrate forming flat disklike mosaic blocks, (001) oriented. Both x-ray core level photoelectron spectroscopy and ultraviolet photoelectron spectroscopy photoemission experiments have been used to study the electronic structure. A first-principles calculation has been performed and compared with the measured spectra. © 2007 The American Physical Society.C.N. acknowledges the Spanish Ministry of Science and Technology FP-2001-1310. This work had the financial support of grants from both MCyT NAN2004-08881- C02-01 and MAT2004-05865 and CM CAM 07N/0023/ 2002Peer Reviewe

Photocatalytic oxidation of pollutants in gas-phase via Ag3PO4-based semiconductor photocatalysts: Recent progress, new trends, and future perspectives

Air pollution has become a significant challenge for both developing and developed nations. due to its close association with numerous fatal diseases such as cancer, respiratory, heart attack, and brain stroke. Over recent years, heterogeneous semiconductor photocatalysis has emerged as an effective approach to air remediation due to the ease of scale-up, ready application in the field, use of solar light and ready availability of a number of different effective photocatalysts. To date, most work in this area has been conducted using UV-absorbing photocatalysts, such as TiO2 and ZnO; However, recent studies have revealed Ag3PO4 as an attractive, visible-light-absorbing alternative, with a bandgap of 2.43 eV. In particular, this material has been shown to be an excellent photocatalyst for the removal of many types of pollutants in the gas phase. However, the widespread application of Ag3PO4 is restricted due to its tendency to undergo photoanodic corrosion and the poor reducing power of its photogenerated conductance band electrons, which are unable to reduce O2 to superoxide •O2−. These limitations are critically evaluated in this review. In addition, recent studies on the modification of Ag3PO4 via combination with the conventional heterojunctions or Z-scheme junctions, as well as the photocatalytic mechanistic pathways for enhanced gas-pollutants removal, are summarized and discussed. Finally, an overview is given on the future developments that are required in order to overcome these challenges and so stimulate further research into this promising field

Social Enterprise in Spain: A Diversity of Roots and a Proposal of Models

The term “social enterprise” was first used, at the end of the 1980s, by organisations that promoted the social and labour integration of persons at risk of social and labour exclusion and other similar social activities. The social economy sector has since slowly introduced this term to describe its entities in order to gain recognition by society, and it is working to promote a generally accepted definition of social enterprise’s behaviour based on the principles and values of the social economy (participation, general interest...). According to Article 5 of Spanish Law 5/2011 on the Social Economy, work integration social enterprises and so-called “special employment centres” are part of the social economy, and so are all firms and entities carrying out activities following the values and principles of the social economy sector. In this context, organisations of the social economy sector also are beginning to use the “social enterprise” concept. In Spain, a debate still exists regarding its exact definition. A mix of perspectives on this concept, with different nuances, can be observed. Besides, the current context of reduced governmental budgets and social services in Spain causes social organisations to adopt new approaches to this term of social enterprise, as this type of organisation is more likely to receive funds from the European Union. This paper’s objective is to analyse all perspectives on the concept of social enterprise as well as the various social enterprise models existing in Spain. The document structure is organized as follow. In the first section, we present the context and the main concepts related to social enterprises in this country. In the second section, we provide an analysis of changes in the evolution of social enterprise criteria to identify established models and emerging patterns. In the third section, we put forward another typology, based on institutionalisation stages. Finally, we conclude by recommending an approach to future work and provide a basic bibliography on the subject

Role of targeted therapies in rheumatic patients on COVID-19 outcomes: Results from the COVIDSER study

Objectives To analyse the effect of targeted therapies, either biological (b) disease-modifying antirheumatic drugs (DMARDs), targeted synthetic (ts) DMARDs and other factors (demographics, comorbidities or COVID-19 symptoms) on the risk of COVID-19 related hospitalisation in patients with inflammatory rheumatic diseases. Methods The COVIDSER study is an observational cohort including 7782 patients with inflammatory rheumatic diseases. Multivariable logistic regression was used to estimate ORs and 95% CIs of hospitalisation. Antirheumatic medication taken immediately prior to infection, demographic characteristics, rheumatic disease diagnosis, comorbidities and COVID-19 symptoms were analysed. Results A total of 426 cases of symptomatic COVID-19 from 1 March 2020 to 13 April 2021 were included in the analyses: 106 (24.9%) were hospitalised and 19 (4.4%) died. In multivariate-adjusted models, bDMARDs and tsDMARDs in combination were not associated with hospitalisation compared with conventional synthetic DMARDs (OR 0.55, 95% CI 0.24 to 1.25 of b/tsDMARDs, p=0.15). Tumour necrosis factor inhibitors (TNF-i) were associated with a reduced likelihood of hospitalisation (OR 0.32, 95% CI 0.12 to 0.82, p=0.018), whereas rituximab showed a tendency to an increased risk of hospitalisation (OR 4.85, 95% CI 0.86 to 27.2). Glucocorticoid use was not associated with hospitalisation (OR 1.69, 95% CI 0.81 to 3.55). A mix of sociodemographic factors, comorbidities and COVID-19 symptoms contribute to patients'' hospitalisation. Conclusions The use of targeted therapies as a group is not associated with COVID-19 severity, except for rituximab, which shows a trend towards an increased risk of hospitalisation, while TNF-i was associated with decreased odds of hospitalisation in patients with rheumatic disease. Other factors like age, male gender, comorbidities and COVID-19 symptoms do play a role.