Scanning electron microscopy and voltammetry of preferentially oriented polycrystalline platinum surfaces

Scanning electron micrographs are taken for a polycrystalline platinum wire before and after the application of a repetitive potential scan at more than 10,000 V/s. The change of the surface structure observed is related to a specific hydrogen adatom voltammogram usually obtained for single crystal surfaces.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Corneal aberrations, contrast sensitivity, and light distortion in orthokeratology patients: 1-year results

Purpose. To evaluate the corneal higher-order aberrations (HOA), contrast sensitivity function (CSF), and light distortion (LD) in patients undergoing orthokeratology (OK). Methods. Twenty healthy subjects (mean age: 21.40 ± 8 years) with mean spherical equivalent refractive error M = −2.19 ± 0.97 D were evaluated at 1 day, 1 month, and 1 year after starting OK treatment. Monocular LD, photopic monocular CSF, and corneal HOA for 6 mm pupil size were measured. Results. LD showed an increase after the first night ( 0.05). Spherical-like, coma-like, and secondary astigmatism HOA RMS increased significantly ( ≤ 0.022) from baseline to 1-month visit, remaining unchanged over the follow-up. Contrast sensitivity for medium frequencies (3.0, 4.24, and 6.00 cpd) was significantly correlated with LD parameters at baseline ( ≤ −0.529, < 0.001). However, after 1 year of treatment, this correlation was only statistically significant for 12 cpd spatial frequency ( ≤ −0.565, < 0.001). Spherical-like RMS for 6 mm pupil size correlated with irregularity of the LD ( = −0.420, < 0.05) at the 1-year visit. Conclusion. LD experienced by OK patients recovers after one month of treatment and remains stable in the long term while optical aberrations remain significantly higher than baseline.This research was supported in part by Projects PTDC/SAUBEB/098391/2008//FCOMP-01-0124-FEDER-010897,PTDC/SAU-BEB/098392/2008, and Strategic Funding UID/FIS/04650/2013

A novel effect. Changes in the electrochemical response of polycrystalline platinum promoted by very fast potential perturbations

It is well established that the voltammogram of polycrystalline platinum in acid electrolyte in the potential range corresponding to the stability of bulk water depends on the electrode history including the type of perturbation applied to the electrode and on the electrolyte composition.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

A novel effect. Changes in the electrochemical response of polycrystalline platinum promoted by very fast potential perturbations

It is well established that the voltammogram of polycrystalline platinum in acid electrolyte in the potential range corresponding to the stability of bulk water depends on the electrode history including the type of perturbation applied to the electrode and on the electrolyte composition.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Peripheral refraction of myopic eyes with spectacle lenses correction and lens free emmetropes during accommodation

To measure axial and off-axis refraction patterns in myopic eyes with spectacle lenses correction and lens free emmetropes in young healthy subjects at different target distances from 2.00 m (0.50 D) to 0.20 m (5.00 D) in terms of sphere, astigmatism, and spherical equivalent refraction. Methods Refraction was measured at the center, 20 and 40 degrees from the line of sight both nasally and temporally in 15 emmetropic and 25 myopic young healthy subjects with an open field, binocular, infrared autorefractor (Grand Seiko WAM-5500, Hiroshima, Japan). Fixation target was a Maltese cross set at 2.00, 0.50, 0.33 and 0.20 m from the corneal plane. Changes in off-axis refraction with accommodation level were normalized with respect to distance axial values and compared between myopic eyes with spectacle lenses correction and lens free emmetropes. Results Off-axis refraction in myopic eyes with spectacle lenses correction was significantly more myopic in the temporal retina compared to lens free emmetropes except for the closest target distance. Relative off-axis refractive error changed significantly with accommodation when compared to axial refraction particularly in the myopic group. This change in the negative direction was due to changes in the spherical component of refraction that became more myopic relative to the center at the 0.20 m distance as the J0 component of astigmatism was significantly reduced in both emmetropes and myopes for the closest target. Conclusion Accommodation to very near targets (up to 0.20 m) makes the off-axis refraction of myopes wearing their spectacle correction similar to that of lens free emmetropes. A significant reduction in off-axis astigmatism was also observed for the 0.20 m distance.This work if supported by Strategic Project PEST-C/FIS/UI607/2011 from the Science and Technology Foundation of Portuguese Ministry of Science and Higher Education

Effect of contact lens surface properties on comfort, tear stability and ocular physiology

Aim: Retrospective analysis of different contact lens wearing groups suggests lens surface lubricity is the main factor influencing contact lens comfort. However, the examined commercially available contact lenses differ in material and design as well as surface properties. Hence this study isolates the contribution of lens surface properties using an ultra-thin coating technology. Methods: Nineteen habitual contact lens wearers (21.6. ±. 1.7years) wore formofilcon B soft monthly disposable contact lenses with and without coating technology modified surface properties for a month each in a randomised double-masked cross-over study. Objective non-invasive: breakup time (NIKBUT), NIKBUT average and ocular redness (Jenvis grading scale) were evaluated (Keratograph 5M) after 1 week and 1 month of wear. Symptoms were assessed using the Contact Lens Dry Eye Questionnaire (CLDEQ-8); perceived vision quality and subjective lens comfort at insertion, mid-day and end of the day were rated with four Visual Analog Scales. Results: Perceived visual quality (F = 5.049,p = 0.037), contact lens dry eye symptoms (F = 14.408,p = 0.001) and subjective lens comfort (F = 28.447,p. . 0.05). Lens surface wettability and ocular redness were not correlated to changes in symptoms (p. >. 0.05). Conclusion: As previously hypothesised, enhancing the physical surface properties of a soft contact lens improves subjectively rated wearer comfort, which, in turn, should result in reduced contact lens discontinuation

Subjective satisfaction in long-term orthokeratology patients

Purpose: To AU3 evaluate the subjective satisfaction in visual stability, night vision complains, and light distortion phenomena, and also the number of hours and days per week of lens wear, in patients with myopia undergoing orthokeratology (OK) treatment for at least 1 year. Methods: A visual analog scale (VAS) questionnaire containing 18 items was administered to 44 patients, 29 women and 15 men (mean age, 24.39 6 9.11 years), with a baseline spherical equivalent refractive error of 22.40 6 0.94 diopters and astigmatism up to 20.5 diopters. Average treatment period by the time of data collection was 19 6 7 months. Patients rated their satisfaction with the correction, with complaints of visual distortion being graded on a scale of 0 to 10, where 0 indicated no discomfort at all. Results: More than 50% of patients skipped lens wear at least 1 night per week. The most common wearing pattern was 6–8 hours a day for 72.7% with 54.5% of patients wearing lenses every 2–3 nights only. Subjective vision scores after lens removal was 9.1 6 1.1 after having worn the lenses and 8.1 6 1.4 after skipping lens wear for 1 night. Subjective vision scores before lens insertion at the end of the day was 6.9 6 2.0 and 5.8 6 2.4, respectively. The number of hours until noticeable blur reduced with increased level of baseline myopia (r = 0.396; P , 0.001). Conclusion: Orthokeratology patients show an irregular wearing pattern after 1 year of treatment that has significant effects on the subjective visual performance over the next day of skipping lens wear. Light distortion under low-light conditions seems to be a transient complication of the treatment and most of the patients report an improvement after the first weeks of treatment.Supported in part by projects PTDC/SAU-BEB/098391/2008//FCOMP-01-0124-FEDER-010897 and PTDC/SAU-BEB/098392/2008//FCOMP-01-0124-FEDER-010898 funded by Fundacao para a Ciencia e Tecnologia (FCT) of Portugal

Automatic classification of new articles in Spanish

We apply machine learning techniques to the automatic classification of news articles from the local newspaper La Capital of Rosario, Argentina. The corpus (LCC) is an archive of approximately 75,000 manually categorized articles in Spanish published in 1991. We benchmark on LCC three widely used supervised learning methods: k-Nearest Neighbors, Na¨ ve Bayes and Arti ficial Neural Networks, illustrating the corpus properties.Eje: V - Workshop de agentes y sistemas inteligentesRed de Universidades con Carreras en Informátic

Response of the aging eye to first day of modern material contact lens wear

Objectives: To investigate the ocular surface of an aged population wearing a daily disposable contact lens over their first day of wear. Methods: Forty eyes from forty presbyopic subjects were fitted a daily CL (Delefilcon A). Tear osmolarity, tear meniscus area (TMA) and ocular surface aberrations (total higher order root means square (RMS)) were assessed at baseline (t0), at 20 minutes (t1) and after 8 hours (t2) of wear. Fluorescein corneal and conjunctival staining and tear break up time (TBUT) were performed at t0 and t2. Results: No statistically significant changes were found between t0, t1 and t2 for TMA, and between t0 and t2 for fluorescein corneal and conjunctival staining. TBUT worsened by the end of the day from 10.4±0.4 seconds t0 to 9.0±0.3 seconds t2 (P <0.05). Osmolarity showed significant changes between t0 306.9±2.3 mOsm/L and t1 312.4±2.4 mOsmol/L (P = 0.02), but returned to baseline values at 8 hours (310.40±2.26 mOsm/L; P = 0.09). Total higher order root means square (RMS) showed significant changes between t0 0.38±0.02 μm and t1 0.61±0.04 μm (P ≤ 0.001) and between t0 and t2 0.64±0.41 μm (P ≤ 0.001). Conclusions: Delefilcon A may induce measures changes (osmolarity and TBUT values) in a presbyopic population, however TMA and vital staining were maintained at the baseline level over the day