Properties of MeNxOy thin films prepared by reactive DC magnetron sputtering

Poster apresentado no E-MRS 2012 SPRING MEETING, Simposio U "Carbon- or Nitrogen-Containing Nanostructured Thin Films"The addition of small amount of nitrogen to a growing MeOy (Me = Metal) film originates a new class of materials with a wide range of different properties, where the optical, electrical and mechanical ones may be tailored between those of the pure oxide, MeOy, and oxynitride, MeNxOy, films, according to the particular application envisaged. The main reason for this is related with the change in the nitride content (which can be either metallic or even insulating-type) of the films promoted by the increasing amounts of nitrogen that are introduced in the films. In this work thin films of MeNxOy were produced using reactive DC magnetron sputtering, using a metallic (Me) target and an Ar/(N2,O2) gas mixture. Preliminary results revealed that the incorporation of nitrogen in the MeOy matrix induces the production of films with electrical and optical responses rather different than the pure oxide that are strongly correlated with its structural arrangement, chemical composition an d morphology changes. On one hand the electrical resistivity and temperature coefficient of resistance were found to have a wide variation, which can be explained using a tunnel barrier conduction mechanism for the electric charge transport through the film, with possible applications in microelectronic devices. The particular morphology of the films induced a broadband optical response with high optical absorption from 290 to 2500 nm, with potential applications in solar cells and thermal photovoltaics.FEDER - Programa Operacional Factores de Competitividade (COMPETE)Fundação para a Ciência e a Tecnologia (FCT) - PTDC/CTM-NAN/112574/2009, PEst-C-FIS/UI607/2011-2012, SFRH/BD/47118/200

AlNxOy thin films deposited by DC reactive magnetron sputtering

AlNxOy thin films were produced by DC reactive magnetron sputtering, using an atmosphere of argon and a reactive gas mixture of nitrogen and oxygen, for a wide range of partial pressures of reactive gas. During the deposition, the discharge current was kept constant and the discharge parameters were monitored. The deposition rate, chemical composition, morphology, structure and electrical resistivity of the coatings are strongly correlated with discharge parameters. Varying the reactive gas mixture partial pressure, the film properties change gradually from metallic-like films, for low reactive gas partial pressures, to stoichiometric amorphous Al2O3 insulator films, at high pressures. For intermediate reactive gas pressures, sub-stoichiometric AlN x O y films were obtained, with the electrical resistivity of the films increasing with the non metallic/metallic ratio.FEDER - Program COMPETE - Programa Operacional Factores de CompetitividadeFundação para a Ciência e a Tecnologia (FCT) - Project PTDC/CTM/69362/2006; PhD grant Nº SFRH/BD/47118/200

A comparative analysis of ex-ante credit spreads: structured finance versus straight debt finance

info:eu-repo/semantics/submittedVersio

Tumor de Buschke-Lowenstein

Introduction: Giant condyloma acuminatum belongs to a spectrum of diseases with malignant degeneration. Clinically, it presents as exophytic, fungating masses, sometimes with a cauliflower-like morphology. Case presentation: We present a case of a 32-year-old female patient with a 180x95x80mm exophytic mass of the vulvar region suggestive of Buschke-Lowenstein Tumour. Treatment included wide local excision with electrosurgery and CO2 vaporization of recurrent focal lesions. Histopathological analysis confirmed the expected diagnosis. Surgery went without complications and the patient is lesion-free at the 12th month of follow-up. Conclusion: There is a lack of consistent trials regarding optimal treatment of BLT. Surgery, when feasible, remains the mainstay of treatment. It allows quick lesion size reduction, with fewer side effects and more rapid return to daily living activities, when compared to other treatment options

Process monitoring during AlNxOy deposition by reactive magnetron sputtering and correlation with the film’s properties

In this work, AlNxOy thin films were deposited by reactive magnetron sputtering, using an aluminum target and an Ar/(N2+O2) atmosphere. The DC magnetron discharge parameters during the deposition process were investigated by optical emission spectroscopy and a plasma floating probe was used. The discharge voltage, the electron temperature, the ion flux and the optical emission lines were recorded for different reactive gas flows, near the target and close to the substrate. This information was correlated with the structural features of the deposits as a first step in the development of a system to control the structure and properties of the films during reactive magnetron sputtering. As the target becomes poisoned, the discharge voltage suffers an important variation, due to the modification of the secondary electron emission coefficient of the target, which is also supported by the evolution of the electron temperature and ion flux to the target. The sputtering yield of the target was also affected, leading to a reduction of the amount of Al atoms arriving to the substrate, according to optical emission spectroscopy results for Al emission line intensity. This behavior, together with the increase of non-metallic elements in the films, allowed obtaining different microstructures, over a wide range of compositions, which induced different electrical and optical responses of films.This research was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011. J. Borges also acknowledges FCT financial support under PhD grant Nº SFRH/BD/47118/2008 (financiado por POPH – QREN – Tipologia 4.1 – Formação Avançada, comparticipado pelo Fundo Social Europeu e por fundos nacionais do MCTES)

Diplopia, Convergent Strabismus, and Eye Abduction Palsy in a 12-Year-Old Boy with Autoimmune Thyroiditis

Pseudotumor cerebri (PTC) is defined by clinical criteria of increased intracranial pressure, elevated intracranial pressure with normal cerebrospinal fluid (CSF) composition, and exclusion of other causes such tumors, vascular abnormalities, or infections. The association of PTC with levothyroxine (LT4) has been reported. A 12-year-old boy has been followed up for autoimmune thyroiditis under LT4. Family history was irrelevant for endocrine or autoimmune diseases. A TSH level of 4.43 μUI/mL (0.39-3.10) motivated a LT4 adjustment from 75 to 88 μg/day. Five weeks later, he developed horizontal diplopia, convergent strabismus with left eye abduction palsy, and papilledema. Laboratorial evaluation revealed elevated free thyroxine level (1.05 ng/dL [0.65-1.01]) and low TSH, without other alterations. Lumbar puncture was performed and CSF opening pressure was 24 cm H2O with normal composition. Blood and CSF cultures were sterile. Brain MRI was normal. LT4 was temporarily discontinued and progressive improvement was observed, with a normal fundoscopy at day 10 and reversion of diplopia one month later. LT4 was restarted at lower dose and gradually titrated. The boy is currently asymptomatic. This case discloses the potential role of LT4 in inducing PTC. Despite its rarity and unclear association, PTC must be seen as a potential complication of LT4, after excluding all other intracranial hypertension causes.info:eu-repo/semantics/publishedVersio

Optical properties of AlNxOy thin films deposited by DC magnetron sputtering

The aluminium oxynitride system offers the possibility to obtain a wide range of optical responses, by combining metallic aluminium, aluminium oxide and aluminium nitride properties, and thus opening a significant number of possible applications. The main purpose of the present work is to study the variation of the optical properties of AlN x O y thin films as a function of their composition (by varying both x and y coefficients), and the correspondent changes in their morphology and structure. The films were deposited by DC reactive magnetron sputtering, with the discharge parameters monitored during the deposition in order to control the chemical composition. The measurements reveal a smooth change of films Reflectance/Transmittance as a function of the concentration ratio of non metallic elements (O+N) to metallic Al, thus revealing the possibility to tailor the films optical properties according to the application envisaged.Fundação para a Ciência e a Tecnologia (FCT) e ao Fundo Europeu de Desenvolvimento Regional (FEDER) – Programa Operacional “Ciência , Tecnologia, Inovação” – PTDC/CTM/69362/2006 e SFRH/BD/47118/200

Ocular Pulse Amplitude and Doppler Waveform Analysis in Glaucoma Patients

PURPOSE: To determine the correlation between ocular blood flow velocities and ocular pulse amplitude (OPA) in glaucoma patients using colour Doppler imaging (CDI) waveform analysis. METHOD: A prospective, observer-masked, case-control study was performed. OPA and blood flow variables from central retinal artery and vein (CRA, CRV), nasal and temporal short posterior ciliary arteries (NPCA, TPCA) and ophthalmic artery (OA) were obtained through dynamic contour tonometry and CDI, respectively. Univariate and multiple regression analyses were performed to explore the correlations between OPA and retrobulbar CDI waveform and systemic cardiovascular parameters (blood pressure, blood pressure amplitude, mean ocular perfusion pressure and peripheral pulse). RESULTS: One hundred and ninety-two patients were included [healthy controls: 55; primary open-angle glaucoma (POAG): 74; normal-tension glaucoma (NTG): 63]. OPA was statistically different between groups (Healthy: 3.17 ± 1.2 mmHg; NTG: 2.58 ± 1.2 mmHg; POAG: 2.60 ± 1.1 mmHg; p < 0.01), but not between the glaucoma groups (p = 0.60). Multiple regression models to explain OPA variance were made for each cohort (healthy: p < 0.001, r = 0.605; NTG: p = 0.003, r = 0.372; POAG: p < 0.001, r = 0.412). OPA was independently associated with retrobulbar CDI parameters in the healthy subjects and POAG patients (healthy CRV resistance index: β = 3.37, CI: 0.16-6.59; healthy NPCA mean systolic/diastolic velocity ratio: β = 1.34, CI: 0.52-2.15; POAG TPCA mean systolic velocity: β = 0.14, CI 0.05-0.23). OPA in the NTG group was associated with diastolic blood pressure and pulse rate (β = -0.04, CI: -0.06 to -0.01; β = -0.04, CI: -0.06 to -0.001, respectively). CONCLUSIONS: Vascular-related models provide a better explanation to OPA variance in healthy individuals than in glaucoma patients. The variables that influence OPA seem to be different in healthy, POAG and NTG patients

Lack of Spontaneous Venous Pulsation: Possible Risk Indicator in Normal Tension Glaucoma?

PURPOSE: Recently, the absence of spontaneous venous pulsation (SVP) has been suggested as a vascular risk factor for primary open-angle glaucoma (POAG). As the mechanism behind this phenomenon is still unknown, the authors have studied this vascular component using colour Doppler imaging (CDI). METHODS: A total of 236 patients were divided into three diagnostic groups: healthy controls (81), POAG (86) and normal tension glaucoma (NTG; 69). All subjects were submitted to CDI studies of the retrobulbar circulation, intraocular pressure measurements and assessment of SVP existence. Mann-Whitney, chi-square contingency tables and Spearman correlations were used to explore differences and correlations between variables in the diagnostic groups. RESULTS: Eighty-two percent of healthy controls had SVP (66/81), while a smaller numbers were registered in both glaucoma groups: POAG - 50% (43/86); NTG - 51% (35/69). In NTG patients, but not in POAG patients, the prevalence of the SVP phenomenon decreases with increased glaucoma damage (p = 0.04; p = 0.55, respectively). Overall glaucoma patients from both groups had lower central retinal vein (CRV) velocities than the healthy controls (p < 0.05). NTG patients with SVP had less severe visual field defects (mean defect -6.92 versus -11.1, p < 0.05), higher [correction added after online publication 21 September 2012; the word 'higher' has been inserted to replace the word 'lower'] peak systolic and mean flow velocities in the central retinal artery (p < 0.01; p < 0.05, respectively) as well as higher [correction added after online publication 21 September 2012; the word higher has been inserted to replace the word lower] maximal velocities and RI of the CRV (p < 0.02; p < 0.05, respectively). CONCLUSIONS: Glaucoma patients have a decrease in CRV velocities. SVP is less prevalent in glaucoma patients than in healthy individuals. This phenomenon apparently reflects different hemodynamic patterns in the central retinal vessels. This variable may be of particular importance in NTG patients, where it may be associated with more advanced functional damage