UV to NIR photon conversion in Nd-doped rutile and anatase titanium dioxide films for silicon solar cell application

Undoped and Nd-doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 °C under 0.1 mbar O2. By selecting adequate substrates, TiO2 films doped with 1, 2 or 5 at.% Nd were grown and constituted with polycrystalline rutile, highly oriented (2 0 0) rutile film, or oriented (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and well-resolved emission lines from Nd3+ have been observed upon excitation above the TiO2 bandgap at room temperature. The sensitised emission of Nd3+ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd3+ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd3+ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd3+ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO2 rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.% Nd3+ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process

UV to NIR photon conversion in Nd-doped rutile and anatase titanium dioxide films for silicon solar cell application

Undoped and Nd-doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 °C under 0.1 mbar O2. By selecting adequate substrates, TiO2 films doped with 1, 2 or 5 at.% Nd were grown and constituted with polycrystalline rutile, highly oriented (2 0 0) rutile film, or oriented (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and well-resolved emission lines from Nd3+ have been observed upon excitation above the TiO2 bandgap at room temperature. The sensitised emission of Nd3+ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd3+ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd3+ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd3+ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO2 rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.% Nd3+ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process

Corporate governance for sustainability : Statement

The current model of corporate governance needs reform. There is mounting evidence that the practices of shareholder primacy drive company directors and executives to adopt the same short time horizon as financial markets. Pressure to meet the demands of the financial markets drives stock buybacks, excessive dividends and a failure to invest in productive capabilities. The result is a ‘tragedy of the horizon’, with corporations and their shareholders failing to consider environmental, social or even their own, long-term, economic sustainability. With less than a decade left to address the threat of climate change, and with consensus emerging that businesses need to be held accountable for their contribution, it is time to act and reform corporate governance in the EU. The statement puts forward specific recommendations to clarify the obligations of company boards and directors and make corporate governance practice significantly more sustainable and focused on the long term

Occupational advice for Patients undergoing Arthroplasty of the Lower limb: An intervention development and feasibility study (The OPAL Study)

Background Hip and knee replacements are regularly performed for patients who work. There is little evidence about these patients’ needs and the factors influencing their return to work. There is a paucity of guidance to help patients return to work after surgery and a need for structured occupational advice to enable them to return to work safely and effectively. Objective(s) To develop an occupational advice intervention to support early recovery to usual activities including work which is tailored to the requirements of patients undergoing hip and knee replacements. To test the acceptability, practicality and feasibility of this intervention within current care frameworks Design An intervention mapping (IM) approach was used to develop the intervention. The research methods employed were: rapid evidence synthesis; qualitative interviews with patients and stakeholders; prospective cohort study; survey of clinical practice; modified Delphi consensus process. The developed intervention was implemented and assessed during the final feasibility stage of the IM process. Setting Orthopaedic departments within NHS secondary care. Participants Patients in work, and intending to return to work following primary elective hip and knee replacement surgery; healthcare professionals and employers. Interventions Occupational advice intervention. Main outcome measures Development of an occupational advice intervention. Fidelity of the developed intervention when delivered in a clinical setting. Patient and clinician perspectives of the intervention. Preliminary assessments of intervention effectiveness and cost. Results A cohort study (154 patients), 110 stakeholder interviews, survey of practice (152 respondents) and evidence synthesis provided the necessary information to develop the intervention. The intervention included information resources, personalized return to work plan and co-ordination from the healthcare team to support the delivery of 13 patient and 20 staff performance objectives (POs). To support delivery, a range of tools (e.g. occupational checklists, patient workbooks, employer information), roles (e.g. return-to-work coordinator) and training resources were created. Feasibility was assessed in 21 of the 26 patients recruited from 3 NHS trusts. Adherence with the defined performance objectives was 75% for patient POs and 74% for staff POs. The intervention was generally well received although the short timeframe available for implementation and concurrent research evaluation led to some confusion amongst patients and those delivering the intervention regarding its purpose and the roles and responsibilities of key staff. Limitations Implementation and uptake of the intervention was not standardized and was limited by the study timeframe. Evaluation of the intervention involved a small number of patients which limited the ability to assess it. Conclusions The developed occupational advice intervention supports best practice. Evaluation demonstrated good rates of adherence against defined performance objectives. However, a number of operational and implementation issues require further attention Future work The intervention warrants a randomised controlled trial to assess its clinical and cost effectiveness to improve rates and timing of sustained return to work after surgery. This research should include the development of a robust implementation strategy to ensure adoption is sustained. Funding This project was funded by the NIHR Health Technology Assessment programme (project number 15/28/02) Trial Registrations International Standard Randomised Controlled Trials Number Trial ID: ISRCTN27426982 International prospective register of systematic reviews (PROSPERO) Registration: CRD4201604523

Croissance par ablation laser pulsé de nouvelles phases d'oxyde de titane pour l'électronique transparente et la conversion de photons

Le photovoltaïque nécessite de nouveaux matériaux pour diminuer ces coûts et améliorer les rendements. Ces travaux de thèse ont concerné le développement de nouvelles phases d'oxyde de titane pour l'électronique transparente et la conversion de photon appliquée au PV silicium. L'ablation laser pulsé est une méthode de croissance particulièrement adaptée pour la prospection de matériaux aux propriétés innovantes. Le contrôle des phases anatase, rutile et d'une phase de composition TiO1.45 épitaxié en fonction de la pression partielle d'oxygène a permis de réaliser des films aux propriétés électriques, optiques innovantes. Un film biphasé anatase/rutile dopé niobium (TNO1.80) présente ainsi une transition métal-semi-conducteur aux alentours de 68K. Par ailleurs, le film de composition TiO1.45 épitaxié s'est révélé être un oxyde transparent conducteur de type p. La découverte de ce nouveau p-TCOs a été valorisée et validée par l'élaboration d'une homojonction p - n transparente. Les matrices d'oxyde de titane rutile et anatase ont également été utilisées pour accueillir des ions terres rares Ln3+ afin de convertir les photons ultra-violet du spectre solaire incident vers le proche infrarouge (800 > > 1100 nm). Le transfert d'énergie des matrices TiO2 vers les dopants Ln3+ a été étudié en fonction de la structure, de la quantité de dopant ainsi que la qualité de la microstructure des films dopés Ln3+ (Ln3+=Pr3+,Tm3+,Eu3+,Yb3+,Nd3+).New materials are needed to decrease cost and improve photovoltaic cell performance. These thesis works are focused on the development of new titanium oxide phases for transparent electronic and photon conversion applied to silicon solar cell. Pulsed laser deposition is an adapted growth method for the prospection of materials with innovating properties. The control of epitaxial growth of anatase, rutile and a phase with a composition TiO1.45 in function of oxygen partial pressure allowed us to realize films with innovating electrical and optical properties. A two phase anatase/rutile film doped niobium (TNO1.80) have shown a metal-semiconductor transition about 68 K. Moreover, transparent TiO1.45 epitaxial thin film has displayed a p-type semiconduction behaviour which has been confirmed by the elaboration of a transparent p - n homojunction. Rutile and anatase titanium oxide matrix were also used to host rare earths ions in order to convert ultraviolet to near infra-red photon (800 > > 1100 nm). TiO2 matrix to dopant transfer has been studied in function of crystal structure, doping content and the quality of microstructure of films doped Ln3+(Ln3+=Pr3+,Tm3+,Eu3+,Yb3+,Nd3+).ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

Indoor fungal contamination: Health risks and measurement methods in hospitals, homes and workplaces.

International audienceAbstract Indoor fungal contamination has been associated with a wide range of adverse health effects, including infectious diseases, toxic effects and allergies. The diversity of fungi contributes to the complex role that they play in indoor environments and human diseases. Molds have a major impact on public health, and can cause different consequences in hospitals, homes and workplaces. This review presents the methods used to assess fungal contamination in these various environments, and discusses advantages and disadvantages for each method in consideration with different health risks. Air, dust and surface sampling strategies are compared, as well as the limits of various methods are used to detect and quantify fungal particles and fungal compounds. In addition to conventional microscopic and culture approaches, more recent chemical, immunoassay and polymerase chain reaction (PCR)-based methods are described. This article also identifies common needs for future multidisciplinary research and development projects in this field, with specific interests on viable fungi and fungal fragment detections. The determination of fungal load and the detection of species in environmental samples greatly depend on the strategy of sampling and analysis. Quantitative PCR was found useful to identify associations between specific fungi and common diseases. The next-generation sequencing methods may afford new perspectives in this area

Optical and structural properties of rare earth-doped TiO2 anatase and rutile thin films grown by PLD

posterInternational audienc