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Refractive Index Measurement (refractive + index_measurement)
Selected AbstractsEquivalences between refractive index and equilibrium water content of conventional and silicone hydrogel soft contact lenses from automated and manual refractometry,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007José M. González-Méijome Abstract Purpose The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. Methods Twelve HEMA-based hydrogels of different hydration and four siloxane-based polymers were assayed. A manual refractometer and a digital refractometer were used. Polynomial models obtained from the sucrose curves of equilibrium water content against refractive index and vice-versa were used either considering the whole range of sucrose concentrations (16,100% equilibrium water content) or a range confined to the equilibrium water content of current soft contact lenses (,20,80% equilibrium water content). Results Values of equilibrium water content measured with the Atago N-2E and those derived from the refractive index measurement with CLR 12,70 by the applications of sucrose-based models displayed a strong linear correlation (r2 = 0.978). The same correlations were obtained when the models are applied to obtain refractive index values from the Atago N-2E and compared with those (values) given by the CLR 12,70 (r2 = 0.978). No significantly different results are obtained between models derived from the whole range of the sucrose solution or the model limited to the normal range of soft contact lens hydration. Conclusions Present results will have implications for future experimental and clinical research regarding normal hydration and dehydration experiments with hydrogel polymers, and particularly in the field of contact lenses. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Li-Deficient, Off-Congruent MgO:LiNbO3 Crystals Prepared by Postgrown Li-Poor Vapor Transport Equilibration for Integrated OpticsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010De-Long Zhang Li-deficient, off-congruent Z -cut MgO:LiNbO3 (MgO:LN) crystals for integrated optics were prepared by carrying out postgrown Li-poor vapor transport equilibration (VTE) treatments on congruently grown MgO (5 mol% in melt):LiNbO3 plates at 1100°C for durations ranging from 40 to 395 h. Secondary ion mass spectrometry analysis, surface ordinary refractive index measurement, and neutron activation analysis were carried out on the VTE crystals to verify that the Mg and Nb ions did not diffuse out of the crystal during the VTE procedure and their distributions over the whole plate retain its homogeneity. The VTE duration dependence of the Li2O content reduction was determined using gravimetric method, and the crystalline phase was by powder X-ray diffraction. The results show that the Li2O content decreases with a prolonged VTE and the Li2O content reduction in the saturation regime is about 2.9 mol%. All of the VTE crystals still retain the LN phase, and Li-vacancy and NbLi are the major defects in the VTE crystal. OH absorption study reveals that the doped MgO concentration is below the photorefractive threshold for all VTE crystals. The optical absorption edge (OAE) of the VTE-treated MgO:LN was also measured as a function of the VTE duration. On the basis of the known Li2O content and measured OAE, the photon-energy fit reported previously, valid for the evaluation of Li2O content in a pure LN, is corrected for the Li-poor VTE-treated MgO:LNs. Finally, the applicability of the Li-deficient off-congruent MgO:LN crystals prepared by the Li-poor VTE method is demonstrated by characterizing the optical damage and Er diffusion properties of a single-mode Ti:MgO:Er:LiNbO3 strip waveguide fabricated on an Li-poor VTE-prepared MgO:LN crystal. [source] Spatial refractive index measurement of porcine artery using differential phase optical coherence microscopyLASERS IN SURGERY AND MEDICINE, Issue 10 2006Jeehyun Kim PhD Abstract Background and Objectives We describe a methodology to record spatial variation of refractive index of porcine renal artery using differential phase optical coherence microscopy (DP-OCM). Study Design/Materials and Methods The DP-OCM provides quantitative measurement of thin specimen phase retardation and refractive index by measuring optical path-length changes on the order of a few nanometers and with a lateral resolution of 3 µm. The DP-OCM instrumentation is an all-fiber, dual-channel Michelson interferometer constructed using a polarization maintaining (PM) fiber. Results Two-dimensional en face dual-channel phase images are taken over a 150,×,200 µm region on a microscopic slide, and the images are reconstructed by plotting a two-dimensional refractive index map as the OCM beam is moved across the sample. Conclusions Because the DP-OCM can record transient changes in the optical path-length, the system may be used to record quantitative optical path-length alterations of tissue in response to various stimuli. A fiber-based DP-OCM may have the potential to substantially improve in vivo imaging of individual cells for a variety of clinical diagnostics, and monitoring applications. Lasers Surg. Med. © 2006 Wiley-Liss, Inc. [source] Determination of linear birefringence of a multiple-order wave plate using a phase-sensitive ellipsometerPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2008H. C. Wei Abstract A phase-sensitive interferometric ellipsometer is setup in order to characterize linearly birefringent parameters (no,ne,m) of a multiple-order wave plate (MWP) precisely where no and ne are refractive indices of ordinary and extraordinary rays respectively while m is the number of the order of interference. In order to avoid multiple reflections in MWP during the phase retardation measurement at oblique incidence, two tilted phase retardations with respect to the oblique incident angle rotated along x-axis and y-axis are measured and then subtracted from each other. In the mean time, the spatial shifting effect of the emerging beams from MWP is reduced too. This results the accuracy of linear birefringence measurement. Finally, a multiple-order quartz wave plate was tested. The experimental results verify that the phase-sensitive interferometric ellipsometer is able to precisely measure linear birefringence and the order number of a MWP. In this measurement, the phase stability of the interferometric ellipsometer was 0.3°/hr. It implies the sensitivity on refractive index measurement at ,n , 10,6 was achieved in the experiment. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Monitoring of blood proteins glycation by refractive index and spectral measurementsLASER PHYSICS LETTERS, Issue 6 2008O.S. Zhernovaya Abstract Monitoring of blood glucose and glycated proteins level is an urgent requirement for diabetic patients. The amount of glycated hemoglobin and glycated albumin depends on blood glucose concentration and reflects the mean glycemia. The purpose of this study is to investigate the effect of presence of glucose and glycation of proteins on optical properties of water solutions of hemoglobin and albumin with different glucose concentrations. We present the results of feasibility study of the refractive index measurements for water solutions of hemoglobin and albumin with glucose by Abbe refractometer. In addition, absorbance spectrum of water solutions of hemoglobin and albumin with different glucose concentrations has been studied. The experimental results show that the changes of optical properties caused by glycation of proteins can be observed by refractive index and spectral measurements. The refractive index measurements can be potentially applied for evaluation of glycated hemoglobin and glycated albumin amount in blood. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Determination of molar mass and solution properties of cationic hydroxyethyl cellulose derivatives by multi-angle laser light scattering with simultaneous refractive index detectionPOLYMER INTERNATIONAL, Issue 10 2009Wei Gao Abstract BACKGROUND: A complete understanding of the molar mass and solution properties of raw materials in bio/pharmaceutical products under bio-application and natural conditions ensures process control, product performance and quality. Biopolymers including polymeric cationic hydroxyethyl cellulose derivatives (e.g. Polyquaterium-10 or Polymer JR) have long been used in health care formulations including shampoos, lotions, eye drops and contact lens multi-purpose solutions. Previously reported molar masses and conformation of Polymer JR were based on size exclusion chromatography-related techniques, which required highly concentrated buffered salt solutions and organic solvent modifiers to prevent undesirable interactions, and did not represent the isotonic conditions in products and applications. RESULTS: This paper describes the characterization of Polymer JR in saline using a new approach that combines micro-batch mode multi-angle laser light scattering with simultaneous refractive index measurements (MB-MALLS-RI). Mass-average molar mass, z -average radius of gyration and second virial coefficient values in phosphate buffer saline (PBS) were obtained and are discussed in detail. CONCLUSION: The molar mass and solution properties of Polymer JR in PBS, with the same pH and ionic strength as most health care solution products, can be characterized using the MB-MALLS-RI technique. The approach is practical and can be widely used for the analysis of other cationic biopolymers. Copyright © 2009 Society of Chemical Industry [source] Ultrasound-facilitated electro-oxidation for treating cyan ink effluentTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2008Chee-Yong Chua Abstract The feasibility of using ultrasonication in combination with the Fenton's reaction was investigated for treating cyan ink effluent. A two-step treatment process was developed,the first step was an ultrasound-assisted electro-oxidation, while the second was chemical oxidation through the addition of hydrogen peroxide. The use of electro-oxidation in the first step significantly reduced the amount of iron needed compared with the conventional Fenton's reaction, resulting in a 98% reduction in the amount of sludge produced. A simple technique based on refractive index measurements was introduced as a rapid way to quantify the amount of sludge produced. It was postulated that ultrasonication in the presence of iron (from electrolysis) in the first step converted the ink components into reaction intermediates which were more amenable to peroxide oxidation in the second step. These intermediates were quantified by ultra-violet absorption at wavelengths of 275,400 nm. The two-step treatment process was able to reduce the COD and copper contents in the ink waste water to within the discharge limit, which conventional Fenton's reaction was unable to meet for copper discharge. The same COD removal was also achieved in about half the time. Kinetics study performed to further understand the reaction mechanisms show second-order kinetics for both steps with activation energies of 18.2 and 20.4 kJ/mol for steps 1 and 2, respectively. On a étudié la possibilité de recourir à l'ultrasonification combinée à la réaction de Fenton pour traiter l'effluent d'encre de cyan. Un procédé de traitement en deux étapes a été mis au point: la première étape consiste en une électro-oxydation assistée par ultrasons, tandis que la seconde consiste en une oxydation chimique par ajout de peroxyde d'hydrogène. Le recours à l'électro-oxydation dans la première étape réduit significativement la quantité de fer requis comparé à la réaction de Fenton classique, entraînant une réduction de 98% de la quantité de suspension produite. Une technique simple basée sur des mesures d'indice de réfraction a été introduite comme une façon rapide d'établir la quantité de suspension produite. On a posé comme postulat que l'ultrasonification en présence de fer (de l'électrolyse) dans la première étape convertit les composantes de l'encre en des intermédiaires de réaction qui étaient plus propices à l'oxydation du peroxyde dans la seconde étape. Ces intermédiaires ont été quantifiés par l'absorption des ultraviolets à des longueurs d'ondes de 275 nm à 400 nm. Ce procédé de traitement en deux étapes a permis de réduire la DCO et les teneurs en cuivre dans l'eau usée de l'encre pour les amener à la limite des normes de rejet, ce que la réaction de Fenton classique n'a pu permettre de réaliser pour le cuivre. Le même retrait de DCO a été également réalisé dans un temps inférieur de 50%. L'étude de cinétique effectuée pour mieux comprendre les mécanismes de réaction montre une cinétique de second ordre pour les deux étapes avec des énergies de désactivation de 18,2 et 20,4 kJ/mol pour les étapes 1 et 2, respectivement. [source] | |||||||||||||