Chemical sensing by differential thermal analysis with a digitally controlled fiber optic interferometer.

In this work the implementation of an optical fiber interferometric system for differential thermal analysis enabling the identification of chemical species is described. The system is based on a white light Mach-Zehnder configuration using pseudo-heterodyne demodulation to interrogate two identical fiber Bragg gratings (FBG) in a differential scheme. System performance is compared using either standard hardware or low cost virtual instrumentation for operation control and signal processing. The operation with the virtual system enabled temperature measurements with a ±0.023 °C resolution nearly matching the performance of the standard hardware. The system ability to discriminate chemical species by differential thermal analysis was demonstrated. Mixed samples of acetone and methanol could be successfully identified, indicating the suitability of the system for high precision measurements using low cost instrumentation.

Ultralong 250 km remote sensor system based on a fiber loop mirror interrogated by an optical time-domain reflectometer.

A 253 km ultralong remote displacement sensor system based on a fiber loop mirror interrogated by a commercial optical time-domain reflectometer is proposed and experimentally demonstrated. The use of a fiber loop mirror increases the signal-to-noise ratio, allowing the system to interrogate sensors placed 253 km away from the monitoring system without using any optical amplification. The displacement sensor was based on a long period grating spliced inside of the loop mirror, which modifies the mirror reflectivity accordingly to the applied displacement.

Highly birefringent photonic bandgap Bragg fiber loop mirror for simultaneous measurement of strain and temperature.

A highly birefringent photonic bandgap Bragg fiber loop mirror configuration for simultaneous measurement of strain and temperature is proposed. The group birefringence and the sharp loss peaks are observable in the spectral response. Because the sensing head presents different sensitivities for strain and temperature measurands, these physical parameters can be discriminated by using the matrix method. It should be noted that this Bragg fiber presents high sensitivity to temperature, of ∼5.75 nm/°C, due to the group birefringence variation. The rms deviations obtained are ±19.32 µÎµ and ±0.5 °C, for strain and temperature measurements, respectively.

Coarse WDM networking of self-referenced fiber-optic intensity sensors with reconfigurable characteristics.

A CWDM network operating in reflective configuration for multiplexing remote Radio-Frequency (RF) self-referenced fiber-optic intensity sensors is analyzed and experimentally investigated. In the described approach, the use of fiber Bragg gratings as spectral selective mirrors allows to implement delay lines in the electrical domain, achieving more compact sensor-heads and easy-reconfigurable sensing points. Two measurement parameters for the sensing heads are defined and comparatively studied in terms of design parameters, linearity, sensitivity and resolution. The proposed sensor configuration is modeled following the Z-transform formalism, which permits an easy analysis of the system frequency response. Experimental results are presented, showing the characterization of the network performance and considering the properties of sensor self-referencing as well as sensor crosstalk.

Optical refractometer based on a birefringent Bragg grating written in an H-shaped fiber.

An optical refractometer based on a birefringent (Hi-Bi) fiber Bragg grating (FBG) written in a new H-shaped fiber structure is proposed. This structure is formed by opening the two holes of a side-hole fiber using chemical etching. When the Hi-Bi FBG is immersed in different liquids, different responses of the slow and fast wavelengths are obtained. The refractometer is also capable of simultaneous measurement of refractive index and temperature.

Simultaneous measurement of multiparameters using a Sagnac interferometer with polarization maintaining side-hole fiber.

A Sagnac interferometer with a section of a polarization maintaining side-hole fiber for multiparameter measurement is proposed. The sensor was experimentally demonstrated to be sensitive to torsion, temperature, and longitudinal strain, simultaneously. The birefringence in the investigated side-hole fiber is induced simultaneously by the elliptical shape of a germanium-doped core and by field overlap with the air holes surrounding the core. The latter effect is purely geometrical and causes high chromatic dispersion of the group birefringence in the long wavelength range, which results in a different period of spectral interference fringes. A different wavelength response is obtained for each interference fringe peak when the fiber is subjected to torsion, temperature, or longitudinal strain. A matrix equation for simultaneous measurement of the three parameters--torsion, temperature, and longitudinal strain--is also proposed.

Biochemical serum profiles in dogs experimentally infected with Angiostrongylus vasorum (Baillet, 1866).

The biochemical profiles of crossbred dogs experimentally infected with the parasite Angiostrongylus vasorum were studied. Two groups of five dogs were experimentally inoculated with 50 and 100 third stage infective larvae (L3) of A. vasorum per kilogram of body weight. A third group of five uninfected animals were used as control. Serum from these animals were used for biochemical tests to measure total and fractioned proteins, urea, creatinine and to determine the activities of aspartate (AST), alanine (ALT) aminotransferase, gamma-glutamyl transferase (GGT), alkaline phosphatase (PAL) and creatine kinase isoenzyme MB (CK-MB). The alpha-1, alpha-2 and beta-globulins fractions showed alterations during acute phase of the infection. No modifications were observed in the biochemical profiles of ALT, AST, GGT, PAL, urea and creatinine. CK-MB was shown to be a good early indicator of cardiac injury in dogs experimentally infected with A. vasorum.

Natural transplacental infection of dairy calves with bovine immunodeficiency virus and estimation of effect on neonatal health.

Many experimental infection studies with bovine immunodeficiency virus (BIV) have been conducted, but neither virus transmission under natural conditions nor longitudinal clinical effects of naturally occurring infections in non-experimental populations are well explored. We tested the hypotheses that BIV is transmitted across the placenta during gestation and that intragestionally infected calves are at increased risk of neonatal disease. A cohort of 59 dairy cows on one farm were enrolled at parturition and the BIV serostatus of the cows and their pre-colostral calves determined with an indirect fluorescent-antibody assay. Moreover, the enrolled calves were monitored thrice weekly for specific clinical signs through the duration of the 30 day neonatal period and the occurrence of clinical signs analyzed for association with calf pre-colostral BIV serostatus and dam BIV serostatus. Confounding due to calf passive immunity and season of birth were also explored. Forty percent of seropositive cows (14/35) gave birth to seropositive calves but no seropositive calves (0/19) were born to seronegative dams (estimated relative risk 16, 95% exact confidence interval 2.6-5.8 x 10(29)). Calf pre-colostral BIV serostatus was not associated with the occurrence or frequency of clinical signs--but dam BIV serostatus was associated with the odds of occurrence of calf hyperthermia and with the frequency of occurrence of calf hyperthermia and hyperventilatory events. This study is inconclusive about the effects of prenatal BIV infection on neonatal health--but it does provide evidence for the natural occurrence of transplacental BIV infection.

Nova tecnica de isoeletrofocalizaçao para a hexose 1-fosfato uridiltransferase / A new technique of isoelectrofocusing for the hexose 1-phosphate uridyltransferase

A deficiencia da enzima hexose 1-fosfato uridiltransferase (GALT) provoca a doença, transmitida por caracter autossomico recessivo, conhecida como galactosemia congenita. O padrao isoeletroforetico da GALT foi estudado em eritrocitos (normais e variante Duarte), leucocitos, fibroblastos de pele em cultura, figado e celulas HEPG2 em cultura, usando mini-gel de poliacrilamida, atraves do Phast System Pharmacia. Os extratos enzimaticos foram preparados em uma soluçao de ditiotreitol a 8mM e concentrados apos centrifugaçao no Minicon A25. A separaçao isoeletroforetica foi feita em 2000V,510Vh e 15 graus Centigrado durante 30 minutos. Apos a separaçao foi feita uma coloraçao especifica para a enzima utilizando um corante de tetrazolio. Os resultados obtidos indicam que a heterogeneidade da GALT pode ser facilmente demonstrada por esta tecnica, que e tambem precisa para o diagnostico dos variantes da GALT.

[Clinical case. Correction of Angle Class I with biprotrusion]. / Caso clínico. Correção de Classe I de Angle com biprotrusão.

The presentation of this case report shows the dentoalveolar and soft tissue alterations produced by Orthodontic treatment. Mechanic sequence included sectional arches and were planned according to the Bioprogressive Therapy. The cephalometric assessment (Ricketts analysis and superimpositions) demonstrates all changes produced by treatment as well as those influenced by growth.