Fiber Bragg grating thermometry application to measure flow: laminar and turbulent regimes.

Flow characteristic properties in pipelines are determined from the temperature evolution, measured by fiber Bragg gratings, after transit of a thermal slug. Results analyze both laminar and turbulent flow regimes.

Bulk Fill flow resin contraction using 3D finite element model and calibration by Fiber Bragg Grating measurement.

Contraction due to polymerization of dental resin can cause failure on the adhesive interfaces, can lead to problems such as the appearance of gaps in the interfaces, postoperative sensitivity, pulp damage and the return of the caries. The objective of this work is the study of stresses on the dental adhesive that are generated by the process shrinkage of resin associated with biting forces. A laboratory experiment measured the strains and temperature inside the Filtek Bulk Fill Flow resin during the process of polymerization using Fiber Bragg Grating sensors in an tooth.

Kinetics of polymerization shrinkage of self-adhesive and conventional dual-polymerized resin luting agents inside the root canal.

Statement Of Problem: Information regarding the shrinkage kinetics and monomer conversion of dual-polymerized conventional and self-adhesive resin luting agents (RLA) in situ is lacking.

Purpose: The purpose of this in vitro study was to evaluate the shrinkage strain and ratio of 1 conventional and 1 self-adhesive RLA by using fiber optic sensors based on Bragg gratings and Vickers hardness in the root canal.

Material And Methods: The root canals of 34 single-rooted premolars were endodontically treated and assigned to 2 groups according to the RLA: RelyX ARC (ARC) and RelyX U200 (U200).

Critical Issues of Double-Metal Layer Coating on FBG for Applications at High Temperatures.

Use of fiber Bragg gratings (FBGs) to monitor high temperature (HT) applications is of great interest to the research community. Standard commercial FBGs can operate up to 600 ∘ C. For applications beyond that value, specific processing of the FBGs must be adopted to allow the grating not to deteriorate.

Water assessment using ultra-weak bioluminescence.

In this paper a method to evaluate the presence of microorganisms of the coliform group in water samples using the ultra-weak bioluminescence (UWB) is proposed. A series of UWB measurements and optical density measurements from cultures of both a set of standard E. coli strain samples, and a set of water samples from a river near Curitiba City in Brazil were performed.

Characterization of femtosecond-inscribed fiber Bragg gratings in the visible spectral region.

The femtosecond-laser pulse inscription and characterization of fiber Bragg gratings for operation at visible wavelengths was performed using several types of optical fibers, including single-mode and graded-index fibers designed for near-infrared wavelengths. The obtained bandwidths are very narrow (∼0.12-0.

An in situ evaluation of the polymerization shrinkage, degree of conversion, and bond strength of resin cements used for luting fiber posts.

Statement Of Problem: The behavior and magnitude of the deformations that occur during polymerization and the behavior of the luting agents of glass fiber posts inside the root canal require quantification.

Purpose: The purpose of this in vitro study was to investigate the in situ polymerization shrinkage, degree of conversion, and bond strength inside the root canal of resin cements used to lute fiber posts.

Material And Methods: Thirty maxillary canines were prepared to lute fiber posts.

In Vivo Pattern Classification of Ingestive Behavior in Ruminants Using FBG Sensors and Machine Learning.

Pattern classification of ingestive behavior in grazing animals has extreme importance in studies related to animal nutrition, growth and health. In this paper, a system to classify chewing patterns of ruminants in in vivo experiments is developed. The proposal is based on data collected by optical fiber Bragg grating sensors (FBG) that are processed by machine learning techniques.

Force monitoring in a maxilla model and dentition using optical fiber Bragg gratings.

The aim of this work is to show the possibility of using fiber optic sensors to instrument inside parts of an artificial maxilla and measure internal tension transmitted by the orthodontic and orthopedic appliances to the dentition and the adjacent bone. Bragg gratings written in a standard optical fiber were used to monitor the maxillary teeth and a multiplexed fiber was used to monitor the surface of the maxillary bone, transversally to the longest axis of the teeth. A Universal Test Machine was used to evaluate the sensitivity of the sensor to the vertical and lateral forces applied on the teeth.

Stepwise fabrication of arbitrary fiber optic tapers.

This work reports a modified flame-brush technique to fabricate fiber tapers with arbitrary waist profiles. The flame-brush approach is used to produce small step reductions in the fiber diameter, or step-tapers, with a constant speed flame brush sweep, while the fiber is uniformly stretched. Arbitrary waist profiles in tapers are fabricated by approximating the taper diameter function to any monotonic function of the fiber length while combining a superposition of step-tapers.

Production of optical notch filters with fine parameter control using regenerated fiber Bragg gratings.

A new method to create a controlled notch filter for attenuation of signals based on regenerated fiber Bragg gratings is experimentally demonstrated. A fine adjustment of the notch depth is achieved by controlling the time of regeneration phenomenon in strongly saturated Bragg gratings written in standard ITU G.652 single-mode fiber.

Benchmark for peak detection algorithms in fiber Bragg grating interrogation and a new neural network for its performance improvement.

This paper presents a benchmark for peak detection algorithms employed in fiber Bragg grating spectrometric interrogation systems. The accuracy, precision, and computational performance of currently used algorithms and those of a new proposed artificial neural network algorithm are compared. Centroid and gaussian fitting algorithms are shown to have the highest precision but produce systematic errors that depend on the FBG refractive index modulation profile.

Photo-induced gratings in thin color center layers on lithium fluoride.

We study the recording of permanent Bragg gratings on surface-colored lithium fluoride (LiF) crystals by using the interference pattern of a continuous-wave UV argon-ion laser operating at 244 nm. Gratings with spatial periodicity ranging from 400 to 1000 nm are written by using a phase-mask interferometer and are stable for several months after the writing process. Absorption and photoluminescence spectra show the bleaching of primary F and F -aggregate laser-active color centers as a result of the process.

Measurement of composite shrinkage using a fibre optic Bragg grating sensor.

Fibre Bragg grating is used to determine resin-based composite shrinkage. Two composite resins (Freedom from SDI and Z100 from 3M) were tested to determine the polymerization contraction behaviour. Each sample of resin was prepared with an embedded fibre Bragg grating.

Aortic stent grafting: a new approach to a deadly diagnosis: one hospital's findings in defining new care processes.

Ruptured abdominal aortic aneurysm (AAA) is the 13th leading cause of death in the United States. Diagnosis is the key to prevention of death from AAA. Millions of Americans harbor this silent, potentially lethal aneurysm.

Control and outcome of a large outbreak of colonization and infection with glycopeptide-intermediate Staphylococcus aureus in an intensive care unit.

Background: Glycopeptide-intermediate Staphylococcus aureus (GISA) is emerging as a cause of nosocomial infection and outbreaks of infection and colonization in intensive care units (ICUs). We describe an outbreak of GISA colonization/infection and the ensuing control measures in an ICU and investigate outcomes of the affected patients.

Methods: We describe an outbreak of GISA colonization and infection that affected 21 patients in a medical ICU at a tertiary care teaching hospital, as well as the measures taken to eradicate the GISA strain.

Identification of retinolisomers by high-performance liquid chromatography not unequivocal up to now.

Former publications dealing with high-performance liquid chromatography (HPLC) of retinol provide inconsistent results and lack evidence for the identification of isomers. For clarification of the problems in this field, the isomeric structure of the major retinol isomers in crystallized form was proven by 1H-NMR, UV absorption spectroscopy and by X-ray analysis. These identified isomeric forms of retinol were separated by HPLC with different eluent mixtures and the chromatograms compared in detail with previously published data.

[1H-NMR spectroscopic study of cysteamine eyedrops].

Background: The efficiency of cysteamine eye drops in the treatment of cystinosis has been demonstrated in several studies: Corneal cystine crystals can be removed by topical cysteamine. Cysteamie 0.5% eye drops were superior to a 0.

Lung surfactant phospholipids associate with polymerizing fibrin: loss of surface activity.

Intraalveolar fibrin formation is a hallmark of many acute and chronic lung inflammatory processes. We investigated the influence of fibrin polymerization on biochemical and biophysical properties of a calf lung surfactant extract (CLSE) used for therapy of neonatal distress syndrome. Thrombin-induced coagulation of human fibrinogen (range, 0.

Spin relaxation of iron in mixed state hemoproteins.

In hemoproteins the relaxation mechanism of iron is Orbach for high spin (HS) and Raman for low spin (LS). We found that in met-hemoglobin and met-myoglobin, under conditions in which the two spin states coexist, both the HS and the LS states relax to the lattice through Orbach-like processes. Alos, very short (approximately 1 ns) and temperature independent transverse relaxation times T2 were estimated.

High and low spin state mixture in methemoglobin and metmyoglobin.

The mixture of low and high iron spin states is studied by electron spin resonance in methemoglobin and in metmyoglobin between 6K and 100K. The crystals contain iron (Fe3) exclusively in the high spin state, while powdered samples show a mixture of high and low spin iron. We detected, for the first time, the low spin state in metmyoglobin at low temperatures.

Quantification of extracorporeal fibrin deposits in haemodialysis with minimal and conventional heparinization.

The effects of minimal intermittent heparinization and of conventional heparinization on endogen fibrinogen concentration as well as on fibrin deposits were studied on 17 on patients hemodialysis. It was shown that the minimal intermittent heparinization did non reduce dialysis efficiency and that a total heparin dosage of 6,000 units is the lowest safe limit.