Metal halide perovskites for energy applications

Exploring prospective materials for energy production and storage is one of the biggest challenges of this century. Solar energy is one of the most important renewable energy resources, due to its wide availability and low environmental impact. Metal halide perovskites have emerged as a class of semiconductor materials with unique properties, including tunable bandgap, high absorption coefficient, broad absorption spectrum, high charge carrier mobility and long charge diffusion lengths, which enable a broad range of photovoltaic and optoelectronic applications. Since the first embodiment of perovskite solar cells showing a power conversion efficiency of 3.8%, the device performance has been boosted up to a certified 22.1% within a few years. In this Perspective, we discuss differing forms of perovskite materials produced via various deposition procedures. We focus on their energy-related applications and discuss current challenges and possible solutions, with the aim of stimulating potential new applications

Obesity and craniofacial variables in subjects with obstructive sleep apnea syndrome: comparisons of cephalometric values

<p>Abstract</p> <p>Background</p> <p>The aim of this paper was to determine the most common craniofacial changes in patients suffering Obstructive Sleep Apnea Syndrome (OSAS) with regards to the degree of obesity. Accordingly, cephalometric data reported in the literature was searched and analyzed.</p> <p>Methods</p> <p>After a careful analysis of the literature from 1990 to 2006, 5 papers with similar procedural criteria were selected. Inclusion criteria were: recruitment of Caucasian patients with an apnea-hypopnea index (AHI) >10 as grouped in non-obese (Body Mass Index – [BMI] < 30) <it>vs</it>. obese (BMI ≥ 30).</p> <p>Results</p> <p>A low position of the hyoid bone was present in both groups. In non-obese patients, an increased value of the ANB angle and a reduced dimension of the cranial base (S-N) were found to be the most common finding, whereas major skeletal divergence (ANS-PNS ^Go-Me) was evident among obese patients. No strict association was found between OSAS and length of the soft palate.</p> <p>Conclusion</p> <p>In both non-obese and obese OSAS patients, skeletal changes were often evident; with special emphasis of intermaxillary divergence in obese patients. Unexpectedly, in obese OSAS patients, alterations of oropharyngeal soft tissue were not always present and did not prevail.</p

High Energy Conversion Efficiency with 3-D Micro-Patterned Photoanode for Enhancement Diffusivity and Modification of Photon Distribution in Dye-Sensitized Solar Cells

Abstract Dye sensitize solar cells (DSSCs) have been considered as the promising alternatives silicon based solar cell with their characteristics including high efficiency under weak illumination and insensitive power output to incident angle. Therefore, many researches have been studied to improve the energy conversion efficiency of DSSCs. However the efficiency of DSSCs are still trapped at the around 10%. In this study, micro-scale hexagonal shape patterned photoanode have proposed to modify light distribution of photon. In the patterned electrode, the appearance efficiency have been obtained from 7.1% to 7.8% considered active area and the efficiency of 12.7% have been obtained based on the photoanode area. Enhancing diffusion of electrons and modification of photon distribution utilizing the morphology of the electrode are major factors to improving the performance of patterned electrode. Also, finite element method analyses of photon distributions were conducted to estimate morphological effect that influence on the photon distribution and current density. From our proposed study, it is expecting that patterned electrode is one of the solution to overcome the stagnant efficiency and one of the optimized geometry of electrode to modify photon distribution. Process of inter-patterning in photoanode has been minimized