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Copyright of Amazonia Investiga is the property of PRIMMATE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The troposphere is a layer of the atmosphere whose co index of refraction N is variable in time and with geography due to variations with height of: temperature T, humidity of water vapor e and atmospheric pressure p. To consider the influence of refraction in the bands of the radio spectrum, it is traditional to use a fictitious radius ae of the Earth and not its real radius. Frequently is used: ae = 8500 km (4/3 of a) - valid for countries with a temperate climate -, for determining field coverage of: the land mobile service (SMT), the radio link lines (RE) and the range of radars. One objective of the work is, based on the existing measurements of T, e and p, to structure theoretical and computational algorithms to determine statistically, until a height of 2 km, the values: means, medians and the standard deviation of N and ae. The periods that are considered of interest: weekly, monthly and annual, starting in 2016 until 2020. The results have been compared and validated with those of other previous investigations, and provide new knowledge. Weekly and monthly statistics are contributions of this work. An important aspect due to external interferences- but little studied and objet of another articleis to specify the occurrence of super refraction and elevated and superficial ducts over the sea. [ABSTRACT FROM AUTHOR]

Introduction: Parthenium hysterophorus is a plant species to which anti-inflammatory and antimicrobial actions are attributed. In the Local Production Centers (LPC) in the country, a bitter broom tincture is made for dermatological conditions; however, a fluid extract is not available as an active pharmaceutical ingredient for the production of more bioavailable semi-solid formulations. Objective: To develop a fluid extract of bitter broom with physicochemical quality for pharmaceutical use. Materials and Methods: A 2³ factorial, two-level design of experiments was carried out with three independent factors [particle size of the plant material, ethanol concentration (menstruum) and contact time between plant material and menstruum]. The response variables considered were: dry residue (%), relative density (g.cm-3), refractive index, pH, ethanolic content (%). The order of selection of the fluid extracts for their preparation was at random based on the experimental design. Results and Discussion: A greater variability for the extracts in the pH and dry residue parameters was observed; however, these are within the limits indicated in the National Formulary of Phytopharmaceuticals and Apipharmaceuticals (NFPA) for other plant species. There is also a coincidence in the refractive index, relative density and ethanolic content with what is described in the form. Conclusions: The quality specifications of the 8 formulations correspond to what is stipulated in the NFPA. The variant of choice, according to comprehensive results, is the one that uses 70% ethanol, 1 mm particle size and 12 h extraction time. [ABSTRACT FROM AUTHOR]

Oils are important in human nutrition and due to their components and characteristics that depend on their origin and type of processing, they are related to health. The objective of this research is to carry out a comparative study of the behavior of pumpkin seed and pumpkin seed oils when subjected to heat treatment in relation to a commercial oil. For this purpose, oils have been obtained from pumpkin and squash seeds by extraction with supercritical CO2 and the commercial oil was soybean oil obtained from the local market. These oils were subjected to a heat treatment at different temperatures (20, 120, 150, 180 and 200 °C) then to a heat treatment at 180 °C at different heating times (0, 10, 30, 60 and 120 min), in each case their physicochemical characteristics (acidity index, peroxide index, refractive index and polar compounds) were determined and for the determination of essential fatty acids they were subjected to heat treatment up to 240 °C. Significant differences were found in the physicochemical parameters and content of fatty acids in the three oils. Soybean oil has better stability in its physicochemical quality (acidity index and peroxide index) up to 150 °C, pumpkin seed and squash oils have stability up to 120 °C. The polar compounds at 180 °C x 120 minutes present percentages of 13,5% in soybeans, 16 % in pumpkin and 15,5 % in pumpkin, the fatty acids in the three oils (at 240 °C) present a decrease in the unsaturated and increase in saturates. It is concluded that pumpkin and squash seed oils are less stable than commercial oil, it is recommended that their consumption should be carried out cold or at a maximum of 120 °C to guarantee their consumable quality. [ABSTRACT FROM AUTHOR]

The Judd-Ofelt analysis is essential because it indicates the influence of rare earth ion doping on the host matrix in which they are found. In the present work, the results of the optical characterization of zinc-tellurite glasses doped with Yb3+ are presented, varying the concentrations of Tm3+ and Er3+ by means of UVVIS absorption spectroscopy and refractive index measurements. From these results, the Judd-Ofelt parameters were obtained, which indicated a structural modification with the addition of rare earth ions in the tellurite glassy matrix, due to the rearrangement of the glassy structure and the breaking of Te-O bonds. [ABSTRACT FROM AUTHOR]

This work is carried out with the purpose of studying theoretically the measurement of the diffusion coefficient (DC) in liquid substances using double exposure holographic interferometry (DEHI). Diffusion has been defined, throughout history, as the phenomenon in which matter moves in a system, from regions with high concentrations to those regions where the concentration is lower, as a consequence of the random movements of its molecules. Diffusion proceeds gradually in the mixture of substances, ending just when the concentrations are equalized; in the case of liquid phase substances, the diffusion of a solute in a solvent. For the study of this process, multiple techniques have been used, among which the optical ones stand out, specifically holographic interferometry, which associates the precision of interferometric measurements with the advantages of holography; by implementing IHDE, it is possible to compare the wavefronts, which in principle were separated in time, thus allowing any type of variation in the analyzed object, however small, to be determined by knowing the characteristic wavelength of the light used. In this article, the theoretical development is presented to obtain the mathematical expression from which the CD in liquids can be calculated, using IHDE, highlighting that this is found through the comparison between interferential fringes of the same order recorded at different times, taking into account the distances, measured from the interface between the two liquids, at which they appear. Finally, an analysis of the expression found and how it is applied from experimentally obtained data is carried out. [ABSTRACT FROM AUTHOR]

Copyright of Avances is the property of Instituto de Informacion Cientifica y Tecnologica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The propolis tincture produced in the Local Production Centers (CPL) of Villa Clara province is in high demand due to its diversity of uses. The total solids content of this product is proving to be less than 10% (permissible limit). Objective: To optimize the processing technology of propolis tincture for pharmaceutical purposes, used in the CPLs of Villa Clara. Materials and Methods: A design of 23 factorial experiments was carried out. The independent factors and their levels were: type of solvent (low level of 70% ethanol and high level of 96% ethanol), extraction time by maceration (7 days low level and 14 days high level) and variety of propolis (brown color low level and reddish brown high level). The response variable to considered was the total solids content. Other quality indexes evaluated were: relative density, refractive index and pH. Results and Discussion: A high total solids content (23.02%) was obtained for the condition where reddish brown propolis, 96% ethanol as solvent and extraction time of 7 days were used. The pH, refractive index and relative density of the tincture gave similar results to those of other tinctures of natural origin reported in the literature. Conclusions: The solvent concentration, propolis variety and extraction time significantly influence the total solids content. The tincture obtained from reddish-brown propolis after 7 days of maceration and 96% ethanol, doubles the minimum permissible limit of total solids. [ABSTRACT FROM AUTHOR]

The objective was to experimentally determine the quality specification limits for the Cucurbita pepo lipid extract, by using the tabulated K method. Using ten consecutive lots, an analysis was carried out of parameters such as specific weight, refractive indexes, acidity, saponification, peroxide, and fatty acid content (palmitic, stearic, oleic and linoleic). The distribution of the data was assessed. Then, the quality specification limits were calculated, for a 95% degree of confidence. The values obtained in the assessment of physical and chemical parameters demonstrated the quality of the extract, by adhering to the normal distribution of data, with probability values above 0.05. Using the tabulated K method were established unilateral quality specification limits to index of acidity and peroxide, fatty acid content, while to specific weight, refractive and saponification indexes were bilateral. The assessed lots of Cucurbita pepo lipid extract have adequate quality, considering the results of the evaluated parameters. The properties of the assessed lots showed a high degree of compliance. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas is the property of Universidad de Santiago de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Zingiber officinale (ginger) belongs to the Zingiberaceae family. It is a species widely used as a home remedy to aid digestion, treat flu, cough, nausea, and other ailments. Its aroma and flavor comes mainly from its essential oil, which has properties as an anti-inflammatory and antioxidant agent. The objective of this research is to extract the essential oil of ginger collected in the department of Quindío, using the hydrodistillation technique coupled to Clevenger and assisted by microwaves with and without previous ultrasound treatment. Determine its physicochemical properties such as relative density, refractive index and its organoleptic properties; additionally, to compare the metabolic content of essential oils obtained by gas chromatography coupled to mass spectrometry. [ABSTRACT FROM AUTHOR]

In the present work the dynamics of solitary waves in optics is reported. The dynamics of these structures is governed by the nonlinear Schrödinger’s general equation. Particle-like behavior is shown, due to the interaction of dispersion and nonlinearity expressed in the nonlinear dependence on the refractive index of the optical medium. The solitons obtained are propagated in an optical fiber without altering their shape and speed and therefore can be considered as a natural means to transmit information or energy without significant losses. Their stability properties depend on the speed of solitonic waves which, in the case of nonlinear dark waves, or bubbles are subsonic. [ABSTRACT FROM AUTHOR]

Aim: This study investigated the bioactive metabolites and antioxidant activity of essential oils of two species of the genus Tagetes. Method: The essential oil was obtained by steam stripping, its extraction performance, relative density, refractive index and its solubility in ethanol (70 % v/v) were subsequently determined. The chemical composition was tested using gas chromatography coupled to mass spectrometry (GC-MS). The antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydracil (DPPH) free radical method and the ABTS*+ radical cation trapping capacity. Results: In the essential oils of the Tagetes species, it was found to identify 26 chemical components for the species Tagetes elliptica Sm. And 16 for Tagetes minuta L., both species presented monoterpenes (61 %) and sesquiterpenes (44 %) as main components. The bioactive metabolites of essential oils between both species of Tagetes were, ß-trans-ocimeno (25.03 %), trans-tagetone (51.37 %), ß-myrcene (2.78) and ß-caryophyllene (1.17 %). The extraction yields ranged between 0.05 and 0.048 %, the density between 0.90 and 0.88 (g/ml) with a refractive index of 1.493 and 1.482 and a positive solubility (v/v) between both species. The antioxidant activity of the essential oil in both species showed a variation between 1.77 and 2.56 mg/mL for DPPH and 21.02 to 41.06 mg/mL for BTS*+. Conclusion: The essential oils of the species Tagetes elliptica Sm. and Tagetes minuta L. are a source of bioactive metabolites that promote antimicrobial and antioxidant potentialities for use as food preservatives. [ABSTRACT FROM AUTHOR]

An experimental and theoretical study of the nonlinear optical properties of two derivatives of 1-Aryl-3-(4-Methoxyphenyl)-5-(Benzo(d)(1,3)Dioxol-5-yl)-2H-pirazolines was carried out. Pyrazolines based on the excitation power of the laser, to establish its potential use in the photonics industry [1]. These compounds already synthesized and characterized by UV-vis spectroscopy, in THF as a solvent, were submitted to readings in the Z-scan system to determine different optical parameters, such as the non-linear refractive index (η2), the absorption coefficient nonlinear (β) and third order electronic susceptibility (X (3)). For these measurements, a Cd Nd: YAG laser emitting at 532 nm, a focus of a 10 cm lens, a 1 mm iris and a cell with a length of 1 mm were used; To support the experimental results, quantum mechanical calculations were performed with the calculation level M06-2X / 6-31 G (2d). This study allowed to correlate the molecular design with the optical properties. [ABSTRACT FROM AUTHOR]

Introduction: Nutritional condition indices are morphophysiological estimators that quantify the nutritional status of organisms. In the natural habitat, unsatisfactory nutritional stage of numerous individuals is an expression of unfavorable factors. Objectives: Determine spatio-temporal variations in the nutritional condition of lobsters Panulirus argus, relate them to variations reported in the benthic community, and to demonstrate, through the application of analytical and morphometric indices, that variations of environmental factors affects both groups of indices due to its potential magnitude and its generalized nature. Methods: Lobsters were captured at six sites. Nutritional condition was estimated by three non-destructive, inexpensive and quick indices also easy to apply, which it means extensive indices: blood refractive index (BRI), relationship between total weight and total length (K), and condition factor (CFA). Because there are no historical records of BRI, longterm variations (60 years) were determined using morphometric indices (Klt and CFA). Data from the periods 1963-1964 (N = 29 001), 1983-1993 (N = 3 123) and 2011-2017 (N = 3 600) were analyzed, separating them in the rainy and dry seasons. Results: In all the periods the nutritional condition varied significantly between sites, but without similarities between periods. Despite this, it increased progressively in three sites. This indicates that factors impacting nutritional condition have a stochastic influence that is constantly changing, which is more characteristic of environmental factors than anthropogenic factors. Although the three indices showed a lower nutritional condition in 2017, only BRI gradually decreased between 2011 (16.6) and 2017 (14.2), which suggests that this index, and the morphometrics (Klt and CFA), express different information. All correlations were statistically significant but greatest coefficients were established between morphometric indices. The total weight and the Klt index did not show differences between rainy and dry seasons. However, BRI and CFA were statistically greater in dry season, a fact that was found for each sex. Both CFA and Klt decreased slightly (P > 0.05) between the first (1963-1964) and the second (1983-1993) period and then increased (P < 0.05) in the current period (2011-2017). Because they both are morphometric indices, this was attributed to the presence of greater weight lobsters. Conclusions: The lowest values in 2017 and gradually decreasing trend in BRI, corroborate the generalized nature of the environmental deterioration in the Gulf of Batabanó, but this was not equally expressed by the three indices. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Universidad del Valle de Guatemala is the property of Universidad del Valle de Guatemala and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Terahertz (THz) radiation or T-Ray defines electromagnetic waves with a frequency range between 0.1 THz and 10 THz. It is possible to categorize radiation detection techniques in the THz band in coherent and incoherent techniques. The main difference between them is that in the coherent technique, both the amplitude and the phase of the received signal are determined; but, in the incoherent technique, only the intensity of the signal is measured. THz spectroscopy in the time domain is generally a coherent method. Direct detectors such as pyroelectrics are mainly incoherent detectors. This article presents the experimental measurement of different materials when irradiated with terahertz radiation, applying THz spectroscopy techniques in the time domain. The radiation is emitted by a photoconductive antenna, excited by a femtosecond laser. The results are obtained by measuring the THz pulse transmitted through the materials by implementing coherent and incoherent detection systems, analyzing the data obtained, it was possible to obtain the refractive index and absorption coefficient, in case of the coherent technique, and the absorption coefficient in the incoherent technique, for the different materials studied in this work. With these results, it is concluded that it is possible to perform a characterization of different types of materials when irradiated with THz radiation, which leads to various applications from safety to quality control. [ABSTRACT FROM AUTHOR]

Essential oils (AE) are used as preservatives in the food industry, due to their physicochemical characteristics and antioxidant activity. The aim of this research was to determine yield (R), specific gravity (GE), refractive index (IR), antioxidant activity (AA) and chemical composition of AE of huacatay (Tagetes minuta), poleo (Minthostachys mollis), rosemary (Rosmarinus officinalis L.) and sachaculantro (Eryngium foetidum L.), plants collected from 52 districts of the Amazon region, Peru. For each AE, fixed-effect variance analysis was used with three replications and cluster analysis. The antioxidant activity was determined with the free radical method 2,2-diphenyl-1-picrylhydracil (DPPH) and its most abundant components were identified with headspace gas chromatography coupled to mass spectrometry. The differences in R, GE and IR were significant between districts. The AA showed no significant difference between the districts, but between the plants itself. Among the most abundant volatile components, 1-adamantanol (44.42%) was identified in huacatay, β-phellandrene (20.85%) in poleo, β-myrcene (34.59%) in rosemary and α-pinene (23.41%) in sachaculantro. It is concluded that the geographic location significantly affects the physicochemical properties of AE. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the stability of the prebiotic fraction in the milk by the heat treatment and during the conservation of the symbiotic fermented milk. Milks with 2.5% fat and 8.5% non-fat solids were prepared from dissolving in skimmed and whole milk powdered milk. To obtain the fermented milk, the technological process of the fermented milk with coagulation in a container was followed. Three samples were taken for analysis of carbohydrates in the following moments: before and after pasteurization, before and after the inoculation, and every seven days during the conservation. The carbohydrates were analyzed by high resolution liquid chromatography coupled to detection by refraction index. Prebiotic fractions remained unchanged after pasteurization, inoculation and during the entire conservation. [ABSTRACT FROM AUTHOR]

Densities of ethanol and 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate [Emim]+ [CF3SO3] aqueous solutions were estimated from refractive index data at different temperatures. The results are within the confidence interval established for densities reported in the literature for these systems and with calculated by using the Dale-Gladstone equation (GD). The estimated densities in this study were used to calculate the molar volumes and partial molar volumes at infinite dilution. The partial molar volume data correlated with the solute concentration and temperature to study qualitatively the interactions present in the treated aqueous solutions. The [Emim]+ [CF3SO3] + water system has a disruptor character on water molecules, whereas in the ethanol + water system the hydrophilic effect predominates over the hydrophobic. [ABSTRACT FROM AUTHOR]

This paper presents a model for obtaining the optical constants of thin films semiconductors. It is possible when there are not interference fringes in the transmittance spectra. Optical constants as the absorption coefficient (α), refractive index (n), extinction coefficient (k) and other physical properties (Gap (Eg) and thickness (d)) were obtained for the Cu2ZnSnSe4 compound by deconvolution experimental spectra. Bhattacharyya model and basic elements of Swanepoel theory were used for analysis of transmittance measurements. The Model presented takes into account considerations of inhomogeneity in the film and surface roughness. Values for the optical constants obtained by the proposed model showed agreement with those obtained for samples from Swanepoel theory, when its implementation was possible. A variation of ± 6 % for thickness values, which were corroborated by performing profilometry measurements, was observed. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia e Ingenieria Neogranadina is the property of Ciencia e Ingenieria Neogranadina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Superficies y Vacío is the property of Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article offers information on the production of silicon dioxide, sol-gel hybrid materials azo-dye methyl red and surfactant Triton X-100. It is mentioned that silica films were made using the composite materials in the sandwich glass-cell. Also, Z-scan techniques were employed to determine the nonlinear refraction index. Information on the use of the films as nonlinear phase contract filter is presented.

The article offers information on the synthesis of fluorinated silicon oxide (SiOF) films by using atmospheric pressure chemical vapor deposition (APCVD) reactor, tetraethoxysilane and ozone. It is mentioned that SiOF films were obtained by varying the temperature of the substrate between 200 to 275 degree Celsius. Also, Fourier transform infrared spectroscopy and Raman spectroscopy were used to determine the chemical bonding structures and ellipsometry for refractive index of the films.

The article offers numerical analysis of the electromagnetic guided waves using non-periodic Thue-Morse layer medium. It is mentioned that the Maxwell's equation for each layer of the waves, d and rational approximations were used. Also, the band structures for different layers were determined through measuring refractive index and thickness of the layers. Information on the band diagrams for the waves is additionally presented.

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recently, a novel data acquisition method has been proposed and experimentally implemented for differential phase-contrast computed tomography (DPC-CT), in which a conventional X-ray tube and a Talbot-Lau-type interferometer were utilized in data acquisition. The divergent nature of the data acquisition system requires a divergent-beam image reconstruction algorithm for DPC-CT. This paper focuses on addressing this image reconstruction issue. We have developed a filtered backprojection algorithm to directly reconstruct theDPC-CT images fromacquired fan-beam data. The developed algorithm allows one to directly reconstruct the decrement of the real part of the refractive index from the measured data. In order to accurately reconstruct an image, the data need to be acquired over an angular range of at least 180°? plus the fan angle. As opposed to the parallel beam data acquisition and reconstruction methods, a 180°?-rotation angle for the data acquisition system does not provide sufficient data for an accurate reconstruction of the entire field of view. Numerical simulations have been conducted to validate the image reconstruction algorithm. [ABSTRACT FROM AUTHOR]

SiO2-ZrO2 and SiO2-HfO2 planar waveguide doped with 0.5 and 5 mol% Er+3 ions were prepared by sol-gel route for integrated optic devices. The films were deposited on v-SiO2 substrates. Chemical, optical and spectroscopic properties were evaluated in order to compare two diferentes annealing proceses: Thermal conventional annealing and CO2 Laser annealing. An increase in the refractive index was observed in all the irradiated samples, and the laser annealing can lead to waveguides with a lower attenuation coefficient comparing with the thermal conventional annealing. Emission in C-telecommunications band was observed at room temperature for all the samples upon excitation at 514 and 980nm. [ABSTRACT FROM AUTHOR]

In this work we presents the results of the optical properties of Er3+-doped no ixide glasses. We prepared samples of fluorophosphates and fluorolead glasses with different concentrations of Er. For all the samples were measured their physical parameters: refractive index and density, and were polished until optical quality with the same optical way. The absorption spectrum were obtained at room temperature in the spectral range from 300 to 1100 nm, and from these were calculated the experiemental oscillator strength. Using the model of intensities 4f - 4f, we obtained the parameters Ωλ (λ = 2, 4, 6), from which were calculated the characteristics spectroscopic parameters: lifetime τR, transition probability AJJ', branching ratio BJJ and non radiative relaxation rate WNR. Based in these paramenters are possible identified transitions for laser applications. [ABSTRACT FROM AUTHOR]

Design and was constructed a bench dedicated to the VIS radiation reflectometry in dielectric interphases, based on a sample carrier, 2 Glan Taylor polarizer, laser diodes and photodiodes that rotate with step motors. The measurement as much of power, frequency, polarization of the radiation, like the rotations, supervises with RS232, NI cards and LabVIEW. They were constructed to motors control cards with modbus ASCII protocol far serial communication with the PC. The system allows extinction of 10-5 and rotations of 0,17 mrad. The refractive index, from the reflection pattern for a certain polarization state calculates. [ABSTRACT FROM AUTHOR]

In this paper, we study basic properties of gain and loss guiding propagation modes in a cylindrical optical fiber with nonlinear effects simulated by a complex-valued refractive index. For this purpose we numerically solve the wave equation using the generalized Douglas scheme applied to the time-domain finite-difference beam propagation method. We compare the nonlinear numerically results with the linear case (real-valued refractive index) and with analytical results. [ABSTRACT FROM AUTHOR]

Biosensors, or sensors based on biological materials, are now used in a wide variety of disciplines, including the food industry, medicine, and environmental science. It is becoming increasingly important for researchers and scientists in these and other fields to have a sound understanding of the different types of biosensors which can be used, the principles behind them, and their advantages and limitations. The special emphasis has been dedicated to Surface Plasmon Resonance biosensors (SPR). Surface Plasmon Resonance (SPR) biosensor, a type of optical biosensor, gained attention due to its speed of detection, high specificity, high sensitivity and possibility of on-line real-time analysis. The surface plasmon resonance device detects minute changes in the refractive index of the sensing surface and its immediate vicinity. This highly sensitive detection is based on a collective excitement of electrons (the surface plasmons) in a metal film on a substrate (such as glass), leading to total absorption of light at a particular angle of incidence which is dependent on the refractive indices on either side of the metal film. [ABSTRACT FROM AUTHOR]

The influence of the magnetic treatment of liquids over density variation viscosity, refractive index, light absorption, pH and surface tension is researched in this work. It is shown that -for the experimental conditions used- no significant statistical variations are observed, except for the surface tension in which the increase of magnetic induction gives rise to an increase tendency. [ABSTRACT FROM AUTHOR]

Copyright of Revista Góndola, Enseñanza y Aprendizaje de las Ciencias is the property of Gondola, Ensenanza y Aprendizaje de las Ciencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)