1,721,059 research outputs found
Thickness dependence of surface plasmon polariton dispersion in transparent conducting oxide films at 1.55 mu m
No full textWe experimentally demonstrate propagation of surface plasmon polaritons in the near-IR window lambda is an element of (1.45 mu m, 1.59 mu m) at the interface of indium-tin-oxide films with different thicknesses deposited on glass. Dispersion of such polaritons is strongly dependent on the film thickness, putting into evidence a regime in which polaritons; at both films's interfaces are coupled in surface supermodes. The experimental data are shown to be in good agreement with the analytical model for thin and absorbing conducting films. Measurements on aluminum-doped zinc oxide, characterized by a redshifted plasma resonance, do not show any surface plasmon polariton excitation in the same wavelength window
Fungal endogenous endophthalmitis secondary to magnusiomyces capitatus
Full text linkWe report the case of a 68-year-old immunocompetent patient with a dilatation of the ascending aorta, intraluminal vegetations, and pseudoaneurysmatic bulging who presented with unilateral fungal endogenous endophthalmitis 8 days after coronary angiogram. The isolated pathogen resulted to be Magnusiomyces capitatus, a filamentous, yeast-like fungus that can be commonly found in normal human microflora, with an immunosuppression-related pathogenicity. A literature research revealed a single case of ophthalmic infection - a keratitis - caused by this pathogen. Furthermore, we add a review of mycotic endophthalmitis related to aortic infection. (c) 2019 The Author(s) Published by S. Karger AG, Base
Effect of the order-disorder transition on the optical properties of Cu2ZnSnS4
No full textThe effect of the order-disorder transition on the band gap of kesterite Cu2ZnSnS4, an interesting material for solar cells, has been investigated by optical spectroscopy. The band gap energy (Eg) decreases continuously with increasing annealing temperature, Ta, and reaches its minimum at Ta ∼ 273 °C. Eg is about 200 meV higher in the most ordered state, than in the fully disordered state. Its value and the transition kinetic depend on the sample stoichiometry. A simplified model able to explain the order degree and stoichiometry effects on the Eg value is developed. Ordering results in narrower Raman peaks without affecting the shape of the photoluminescence spectrum - except for the change in Eg - or the characteristic energy of the exponential tail below the fundamental absorption edge. Although a prolonged annealing increases the order degree, the material properties are still influenced by residual disorder as well as by defects related to the off-stoichiometry composition
Optical spectroscopy and microscopy of radiation-induced light-emitting point defects in lithium fluoride crystals and films
No full textBroad-band light-emitting radiation-induced F2 and F3+ electronic point defects, which are stable and laser-active at room temperature in lithium fluoride crystals and films, are used in dosimeters, tuneable color-center lasers, broad-band miniaturized light sources and novel radiation imaging detectors. A brief review of their photoemission properties is presented, and their behavior at liquid nitrogen temperatures is discussed. Some experimental data from optical spectroscopy and fluorescence microscopy of these radiation-induced point defects in LiF crystals and thin films are used to obtain information about the coloration curves, the efficiency of point defect formation, the effects of photo-bleaching processes, etc. Control of the local formation, stabilization, and transformation of radiation-induced light-emitting defect centers is crucial for the development of optically active micro-components and nanostructures. Some of the advantages of low temperature measurements for novel confocal laser scanning fluorescence microscopy techniques, widely used for spatial mapping of these point defects through the optical reading of their visible photoluminescence, are highlighted. © 2012 American Institute of Physics
Thickness dependence of surface plasmon polariton dispersion in transparent conducting oxide films at 1.55 mu m
No full textDiabetic Macular Edema Correlations with Available Diabetes Therapies - Evidence Across a Qualitative Review of Published Literature from MEDLINE and EMBASE
No full textDiabetic macular edema (DME) is the leading cause of visual loss and legal blindness in people with diabetes mellitus. The pathogenesis of DME is complex and multifactorial, and involves both local and systemic risk factors that may alter the blood-retina barrier and allow leakage of protein and fluid into the macula. Recently, in addition to well known risk factors, the use of thiazolidinediones (glitazones) has been related to the development and worsening of DME. This review is based on available literature derived from EMBASE and MEDLINE, from 1950 to May 2010, and focuses on the potential correlations between DME and current available therapies for type 1 and 2 diabetes. This review reveals that the current literature, with the potential exception of glitazones, is not sufficient for a definite statement on the association between DME and currently available diabetic therapies. In fact, among antidiabetic agents, the class of glitazones appears the only one to be potentially associated with DME. Furthermore, adequately powered, prospective studies are warranted to evaluate the exact causal association between glitazones and DME and to exclude the role of other confounding factors potentially able to induce or exacerbate macular edema. Improvement of the quality and reporting in postmarketing surveillance and the use of the 'dechallenge and rechallenge' approach in case of suspicious cause/effect drug relationship of DME are highly encouraged
Temperature effects on sputtered ITO
No full textIndium Tin Oxide (ITO) is widely used in solar cell devices for its excellent electrical and optical characteristics, such as high transparency in the Ultraviolet-Visible range and good conductivity (around 104W-1cm-1). In this work we have compared thin (70-150 nm) ITO layers deposited by Direct Current or Radio Frequency sputtering. We have used different substrate temperatures during film growthand have afterwards thermally annealed the samples at different temperatures up to 300 °C to investigate the effects on the electrical and optical properties of the material. We have found out that the different growth/annealing conditions induce changes in the optical properties of the samples as well as in the conductivity and carrier concentration. © 2018 IEEE
Open circuit voltage reduction due to recombination at the heterojunction solar cell edge
No full textToday to achieve high efficiency solar cells, the crystalline silicon (c-Si) heterojunction (HJ) represents one of the best available options. The key factor of its success is the high open circuit voltage (Voc) achievable, because of the excellent surface passivation due to the intrinsic amorphous silicon (a-Si:H) layers. During cells manufacturing, the a-Si:H film deposition is simultaneously performed on both c-Si wafer sides, and consequently also on the edges of the wafer. However, the wafer edges could result non-passivated in many cases such as the so-called shingling manufacturing route. Moreover, at laboratory level it is quite common to manufacture small area cells from larger wafers. When a silicon edge is left uncovered by cutting, a recombining region is created due to the silicon non-passivated surface. This, in principle, leads to a reduction in the Voc of the cell. Nevertheless, this is not experienced for large area cells cut in half but it is commonly observed that cutting silicon HJ edges results in a lowering in Voc. In this work we have analyzed the correlation between the Voc, the cell area and the recombining surface introduced by cutting the cell into a smaller one. We have monitored the Voc as a function of the cell area during time, and we also have investigated the possibility of a re-passivation of the cell edges by depositing a thick a-Si:H layer after masking the sun exposed cell surface, exploring different deposition conditions to avoid re-annealing of the existing a-Si:H layers
Silicon heterojunction solar cells toward higher fill factor
No full textOne of the most limiting factors in the record conversion efficiency of amorphous/crystalline silicon heterojunction solar cells is the not impressive fill factor value. In this work, with the aid of a numerical model, the ways to enhance the cell fill factor up to 85% are investigated in detail, considering the properties of conventional amorphous-doped films, wider Energy gap layers, and transparent conductive oxide films. The band alignment among the various materials composing the heterojunction is the key to high efficiency but becomes an issue for the solar cell fill factor, if not well addressed. One of the most interesting outcomes of this work is the evidence of hidden barriers arising between the transparent conductive oxide and both selective contacts, due to the mismatch between their work functions. The measurement of light current-voltage characteristics performed at low temperature is proposed as a way to identify the presence of these barriers in efficient solar cells that do not possess high fill factor values. Experimental J-V characteristics compared with numerical simulations demonstrated that the sometimes neglected cell base contact needs instead a more careful consideration. To this aim, a model to predict the presence of a hidden barrier at the base contact that limits the cell fill factor is proposed
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