Alveolar graft in the cleft lip and palate patient: review of 104 cases

Introduction: Alveolar bone grafting is a vital part of the rehabilitation of cleft patients. The factors that have been most frequently associated with the success of the graft are the age at grafting and the pre-grafting orthodontic treatment. Objectives: 1) Describe the cases of alveolar bone grafts performed at the Maxilofacial Unit of Hospital Sant Joan de Déu, Barcelona (HSJD); and 2) Analyze the success/failure of alveolar grafts and related variables. Material and Methods: Descriptive retrospective study using a sample of 104 patients who underwent a secondary alveolar graft at the Craniofacial Unit of HSJD between 1998 and 2012. The graft was done by the same surgeon in all patients using bone from the iliac crest. Results: 70% of the patients underwent the procedure before the age of 15 (median 14.45 years); 70% of the graft patients underwent pre-graft maxillary expansion. A total of 100 cases were recorded as successful (median age of 14.58 years, 68 underwent pre-graft expansion) and only 4 were recorded as failures (median age of 17.62 years, 3 underwent pre-graft expansion). We did not find statistically significant differences in age at the time of grafting or pre-surgical expansion when comparing the success and failure groups. We found the success rate of the graft to be 96.2%. Conclusions: The number of failures was too small to establish a statistically significant conclusion in our sample regarding the age at grafting and pre-grafting expansion. The use of alveolar bone grafting from the iliac crest has a very high success rate with a very low incidence of complications. Existing controversies regarding secondary bone grafting and the wide range of success rates found in the literature suggest that it is necessary to establish a specific treatment protocol that ensures the success of this procedure

Embedment of metal nanoparticles in GaAs and Si for plasmonic absorption enhancement in intermediate band solar cells

The high near-field enhancement occurring in the vicinity of metallic nanoparticles (MNPs) sustaining surface plasmons can only be fully exploited in photovoltaic devices if the MNPs are placed inside their semiconducting material, in the photoactive region. In this work an experimental procedure is studied to embed MNPs in gallium arsenide (GaAs) and silicon (Si), which can be applied to other semiconductor host materials. The approach consists in spin-coating colloidal MNPs dispersed in solution onto the substrate surface. Then a capping layer of the same material as the substrate is deposited on top to embed the MNPs in the semiconductor. The extinction spectra of silver (Ag) and gold (Au) MNPs embedded in GaAs and Si is modeled with Mie theory for comparison with optical measurements. This contribution constitutes the initial step towards the realization of quantum-dot intermediate band solar cells (QD-IBSC) with MN

Raising the Efficiency Limit of the GaAs-based Intermediate Band Solar Cell Through the Implementation of a Mololithic Tandem with an AlGaAs top Cell.

The high efficiency limit of the intermediate band solar cell (IBSC) corresponds to the case of using as intermediate band (IB) host material a semiconductor with gap in the range of 2 eV. Traditional photovoltaic materials, such as Si and GaAs, are not appropriate to produce IB devices because their gaps are too narrow. To overcome this problem, we propose the implementation of a multi-junction device consisting of an IBSC combined with a single gap cell. We calculate the efficiency limits using the detailed balance model and conclude that they are very high (> 60% under maximum concentration) for any fundamental bandgap from 0.7 to 3.6 eV in the IBSC inserted in the tandem. In particular, the two-terminal tandem of a GaAs-based IBSC current matched to an optimized AlGaAs top cell has an efficiency limit as high as 64%

Innovations in Training and Information in Jobs under Ubiquitous Computing and Distributing in Mobile Devices, Smartphones and Tablets

Dentro de la prevención de riesgos laborales, la formación e información en el puesto de trabajo es una obligación a efectos legales con gran proyección e importancia tanto para el trabajador como para el empresario como recurso preventivo. Para que el proceso formativo e informativo sea eficiente y cumpla con el objetivo de la prevención, las metodologías de aprendizaje y enseñanza deben adaptarse a las características del trabajador, al ambiente de trabajo y contexto de impartición. Actualmente, los métodos y herramientas carecen de cercanía y no son atractivos para los trabajadores. El presente trabajo tiene el objetivo de diseñar un modelo de formación e información para el puesto de trabajo desde la innovación didáctica con el uso de las tecnologías de la información más próximas al trabajador, apoyado con la computación ubicua como eje metodológico y utilizando los dispositivos móviles. La herramienta estará destinada a la autoformación situada en el contexto de trabajo del trabajador e incorpora diferentes estrategias didácticas tanto para el aprendizaje como para el seguimiento del mismo por los responsables en prevención de riesgos laborales de la empresa.Within the prevention of labour risks, training and information in the job position is an obligation for legal purposes with a big importance and projection not only for the employer but for the employee as a preventive resource. So in order to get a formative an efficient process and to fulfil the prevention process, the learning and teaching methodologies should be adapted to the characteristics of the employee, to the working environment and to the teaching context. Nowadays, the methodology and tools are not very attractive for the employees. This current work aims to design a model of training and information for the jobs from the didactic innovation with the use of the information technologies closer to the employees, supporting ubiquitous computing as the central concepts of the methodology and using mobile devices. This tool is designed for self training in the context of employees and it has different didactic strategies, for the learning and monitoring by the responsible parties in the company

Modelling and Characterization of Multiple Level Intermediate Band Solar Cell

Intermediate band solar cells (IBSCs) are a new kind of devices capable of surpassing the Shockley Queisser efficiency limit for conventional solar cells. This novel technology requires the use of a new type of material named intermediate band (IB) material which makes a better use of the solar spectrum thanks to the existence of a collection of electronic levels within the band gap of the semiconductor. Quantum Dots (QDs) remain as a feasible technology to implement IB materials. InAs/GaAs QD-IBSCs were manufactured in order to test the validity of the concept, although their real size and shape are far from the optimum. This causes extra electron levels to appear within the nanostructure confining potential, degrading the performance of the device. In this paper, the effect of these extra levels will be studied through a multiple level IBSC model based on the detailed balance, but modified so a term accounting for the non-radioactive recombination (NRR) is also included. The model is completed with constant fitting parameters so the concentration JL-VOC curves (which do not incorporate series resistance effects) can be fitted. Several QD-IBSCs where manufactured, measured and fitted with this model, rendering relevant information about the recombination nature of the QD-IBSC

Modeling and characterization of multiple level intermediate band solar cell

Intermediate band solar cells (IBSCs) are a new kind of devices capable of surpassing the Shockley Queisser efficiency limit for conventional solar cells. This novel technology requires the use of a new type of material named intermediate band (IB) material which makes a better use of the solar spectrum thanks to the existence of a collection of electronic levels within the band gap of the semiconductor. Quantum Dots (QDs) remain as a feasible technology to implement IB materials. InAs/GaAs QD-IBSCs were manufactured in order to test the validity of the concept, although their real size and shape are far from the optimum. This causes extra electron levels to appear within the nanostructure confining potential, degrading the performance of the device. In this paper, the effect of these extra levels will be studied through a multiple level IBSC model based on the detailed balance, but modified so a term accounting for the non-radiative recombination (NRR) is also included. The model is completed with constant fitting parameters so the concentration JL-VOC curves (which do not incorporate series resistance effects) can be fitted. Several QD-IBSCs where manufactured, measured and fitted with this model, rendering relevant information about the recombination nature of the QD-IBSCs

Understanding the operation of quantum dot intermediate band solar cells

In this paper, a model for intermediate band solar cells is built based on the generally understood physical concepts ruling semiconductor device operation, with special emphasis on the behavior at low temperature. The model is compared to JL-VOC measurements at concentrations up to about 1000 suns and at temperatures down to 20 K, as well as measurements of the radiative recombination obtained from electroluminescence. The agreement is reasonable. It is found that the main reason for the reduction of open circuit voltage is an operational reduction of the bandgap, but this effect disappears at high concentrations or at low temperatures

Intermediate band solar energy conversion in ZnTeO

Energy conversion in solar cells incorporating ZnTeO base layers is presented. The ZnTeO base layers incorporate intermediate electronic states located approximately 0.4eV below the conduction band edge as a result of the substitution of O in Te sites in the ZnTe lattice. Cells with ZnTeO base layers demonstrate optical response at energies lower than the ZnTe bandedge, a feature that is absent in reference cells with ZnTe base layers. Quantum efficiency is significantly improved with the incorporation of ZnSe emitter/window layers and transition from growth on GaAs substrates to GaSb substrates with a near lattice match to ZnTe

Self-organized colloidal quantum dots and metal nanoparticles for plasmon-enhanced intermediate-band solar cells

A colloidal deposition technique is presented to construct long-range ordered hybrid arrays of self-assembled quantum dots and metal nanoparticles. Quantum dots are promising for novel opto-electronic devices but, in most cases, their optical transitions of interest lack sufficient light absorption to provide a significant impact in their implementation. A potential solution is to couple the dots with localized plasmons in metal nanoparticles. The extreme confinement of light in the near-field produced by the nanoparticles can potentially boost the absorption in the quantum dots by up to two orders of magnitude. In this work, light extinction measurements are employed to probe the plasmon resonance of spherical gold nanoparticles in lead sulfide colloidal quantum dots and amorphous silicon thin-films. Mie theory computations are used to analyze the experimental results and determine the absorption enhancement that can be generated by the highly intense near-field produced in the vicinity of the gold nanoparticles at their surface plasmon resonance. The results presented here are of interest for the development of plasmon-enhanced colloidal nanostructured photovoltaic materials, such as colloidal quantum dot intermediate-band solar cells

Intermediate band to conduction band optical absorption in ZnTeO

ZnTe doped with high concentrations of oxygen has been proposed in previous works as an intermediate band (IB) material for photovoltaic applications. The existence of extra optical transitions related to the presence of an IB has already been demonstrated in this material and it has been possible to measure the absorption coefficient of the transitions from the valence band (VB) to the IB. In this study, we present the first measurement of the absorption coefficient associated with transitions from the IB to the conduction band (CB) in ZnTeO. The samples used are 4-mum-thick ZnTe layers with or without O in a concentration ~10 19 cm -3, which have been grown on semiinsulating GaAs substrates by molecular beam epitaxy (MBE). The IB-CB absorption coefficient peaks for photon energies ~0.4 eV. It is extracted from reflectance and transmittance spectra measured using Fourier transform infrared (FTIR) spectroscopy. Under typical FTIR measurement conditions (low light intensity, broadband spectrum), the absorption coefficient in IB-to-CB transitions reaches 700 cm -1. This is much weaker than the one observed for VB-IB absorption. This result is consistent with the fact that the IB is expected to be nearly empty of electrons under equilibrium conditions in ZnTe(O)