Development of tube-packaged FBG strain sensor and application in the vibration experiment of submarine pipeline model

NASA Astrophysics Data System (ADS)

Ren, Liang; Li, Hong-Nan; Sun, Li; Li, Dong-Sheng

2005-02-01

Optical fiber sensors have received increasing attention in the fields of aeronautic and civil engineering for their superior ability of explosion proof, immunity to electromagnetic interference and high accuracy, especially fitting for measurement applications in harsh environment. In this paper, a novel FBG (fiber Bragg grating) strain sensor, which was packaged in a 1.2mm stainless steel tube by epoxy resin, was developed. Experiments were conducted on the universal material testing machine to calibrate its strain transferring characteristics. The sensor has the advantages of small size, high precision and flexible use, and demonstrates promising potentials. Ten of tube-packaged strain FBG sensors were applied in the vibration experiment of submarine pipeline model. The strain measured by FBG sensor agrees well with the electric resistance strain sensor.

Monitoring of hardening and hygroscopic induced strains in a calcium phosphate bone cement using FBG sensor.

PubMed

Bimis, A; Karalekas, D; Bouropoulos, N; Mouzakis, D; Zaoutsos, S

2016-07-01

This study initially deals with the investigation of the induced strains during hardening stage of a self-setting calcium phosphate bone cement using fiber-Bragg grating (FBG) optical sensors. A complementary Scanning Electron Microscopy (SEM) investigation was also conducted at different time intervals of the hardening period and its findings were related to the FBG recordings. From the obtained results, it is demonstrated that the FBG response is affected by the microstructural changes taking place when the bone cement is immersed into the hardening liquid media. Subsequently, the FBG sensor was used to monitor the absorption process and hygroscopic response of the hardened and dried biocement when exposed to a liquid/humid environment. From the FBG-based calculated hygric strains as a function of moisture concentration, the coefficient of moisture expansion (CME) of the examined bone cement was obtained, exhibiting two distinct linear regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Strain features and condition assessment of orthotropic steel deck cable-supported bridges subjected to vehicle loads by using dense FBG strain sensors

NASA Astrophysics Data System (ADS)

Wei, Shiyin; Zhang, Zhaohui; Li, Shunlong; Li, Hui

2017-10-01

Strain is a direct indicator of structural safety. Therefore, strain sensors have been used in most structural health monitoring systems for bridges. However, until now, the investigation of strain response has been insufficient. This paper conducts a comprehensive study of the strain features of the U ribs and transverse diaphragm on an orthotropic steel deck and proposes a statistical paradigm for crack detection based on the features of vehicle-induced strain response by using the densely distributed optic fibre Bragg grating (FBG) strain sensors. The local feature of strain under vehicle load is highlighted, which enables the use of measurement data to determine the vehicle loading event and to make a decision regarding the health status of a girder near the strain sensors via technical elimination of the load information. Time-frequency analysis shows that the strain contains three features: the long-term trend item, the short-term trend item, and the instantaneous vehicle-induced item (IVII). The IVII is the wheel-induced strain with a remarkable local feature, and the measured wheel-induced strain is only influenced by the vehicle near the FBG sensor, while other vehicles slightly farther away have no effect on the wheel-induced strain. This causes the local strain series, among the FBG strain sensors in the same transverse locations of different cross-sections, to present similarities in shape to some extent and presents a time delay in successive order along the driving direction. Therefore, the strain series induced by an identical vehicle can be easily tracked and compared by extracting the amplitude and calculating the mutual ratio to eliminate vehicle loading information, leaving the girder information alone. The statistical paradigm for crack detection is finally proposed, and the detection accuracy is then validated by using dense FBG strain sensors on a long-span suspension bridge in China.

Fiber optic strain monitoring of textile GFRP during RTM molding and fatigue tests by using embedded FBG sensors

NASA Astrophysics Data System (ADS)

Kosaka, Tatsuro; Osaka, Katsuhiko; Nakakita, Satoru; Fukuda, Takehito

2003-08-01

This paper describes cure and health monitoring of glass fiber reinforced plastics (GFRP) textile composites both during a resin transfer molding (RTM) process and in loading tests. Carbon fiber reinforced plastics (CFRP) textile composites also were used for a comparative study. Fiber Bragg grating (FBG) fiber optic sensors were embedded in FRP to monitor internal strain. From the results of cure monitoring, it was found that the embedded FBG sensors were useful to know when cured resin constrained fibers. It also appeared that specimens were subjected to friction stress resulted from difference of coefficient of thermal expansion between FRP and a stainless steel mold in cooling process of RTM molding. After the molding, tensile and fatigue tests were conducted. The results of tensile tests showed that output of the embedded FBG sensors agreed well that of surface-bonded strain gauges despite deterioration of reflected spectra form the sensors. From the results of fatigue tests, the FBG sensors showed good status until 100,000 cycles when specimens had no damage. From these results, it can be concluded that embedded FBG sensors have good capability of monitoring internal strain in textile FRP both during RTM process and in service.

Distributed strain measurement based on long-gauge FBG and delayed transmission/reflection ratiometric reflectometry for dynamic structural deformation monitoring.

PubMed

Nishiyama, Michiko; Igawa, Hirotaka; Kasai, Tokio; Watanabe, Naoyuki

2015-02-10

In this paper, we propose a delayed transmission/reflection ratiometric reflectometry (DTR(3)) scheme using a long-gauge fiber Bragg grating (FBG), which can be used for dynamic structural deformation monitoring of structures of between a few to tens of meters in length, such as airplane wings and helicopter blades. FBG sensors used for multipoint sensing generally employ wavelength division multiplexing techniques utilizing several Bragg central wavelengths; by contrast, the DTR(3) interrogator uses a continuous pulse array based on a pseudorandom number code and a long-gauge FBG utilizing a single Bragg wavelength and composed of simple hardware devices. The DTR(3) scheme can detect distributed strain at a 50 cm spatial resolution using a long-gauge FBG with a 100 Hz sampling rate. We evaluated the strain sensing characteristics of the long-gauge FBG when attached to a 2.5 m aluminum bar and a 5.5 m helicopter blade model, determining these structure natural frequencies in free vibration tests and their distributed strain characteristics in static tests.

Oil pipeline geohazard monitoring using optical fiber FBG strain sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Salazar-Ferro, Andres; Mendez, Alexis

2016-04-01

Pipelines are naturally vulnerable to operational, environmental and man-made effects such as internal erosion and corrosion; mechanical deformation due to geophysical risks and ground movements; leaks from neglect and vandalism; as well as encroachments from nearby excavations or illegal intrusions. The actual detection and localization of incipient and advanced faults in pipelines is a very difficult, expensive and inexact task. Anything that operators can do to mitigate the effects of these faults will provide increased reliability, reduced downtime and maintenance costs, as well as increased revenues. This talk will review the on-line monitoring of an extensive network of oil pipelines in service in Colombia using optical fiber Bragg grating (FBG) strain sensors for the measurement of strains and bending caused by geohazard risks such as soil movements, landslides, settlements, flooding and seismic activity. The FBG sensors were mounted on the outside of the pipelines at discrete locations where geohazard risk was expected. The system has been in service for the past 3 years with over 1,000 strain sensors mounted. The technique has been reliable and effective in giving advanced warning of accumulated pipeline strains as well as possible ruptures.

Measurement of longitudinal strain and estimation of peel stress in adhesive-bonded single-lap joint of CFRP adherend using embedded FBG sensor

NASA Astrophysics Data System (ADS)

Ning, X.; Murayama, H.; Kageyama, K.; Uzawa, K.; Wada, D.

2012-04-01

In this research, longitudinal strain and peel stress in adhesive-bonded single-lap joint of carbon fiber reinforced plastics (CFRP) were measured and estimated by embedded fiber Bragg grating (FBG) sensor. Two unidirectional CFRP substrates were bonded by epoxy to form a single-lap configuration. The distributed strain measurement system is used. It is based on optical frequency domain reflectometry (OFDR), which can provide measurement at an arbitrary position along FBG sensors with the high spatial resolution. The longitudinal strain was measured based on Bragg grating effect and the peel stress was estimated based on birefringence effect. Special manufacturing procedure was developed to ensure the embedded location of FBG sensor. A portion of the FBG sensor was embedded into one of CFRP adherends along fiber direction and another portion was kept free for temperature compensation. Photomicrograph of cross-section of specimen was taken to verify the sensor was embedded into proper location after adherend curing. The residual strain was monitored during specimen curing and adhesive joint bonding process. Tensile tests were carried out and longitudinal strain and peel stress of the bondline are measured and estimated by the embedded FBG sensor. A two-dimensional geometrically nonlinear finite element analysis was performed by ANSYS to evaluate the measurement precision.

Integration of miniature Fabry-Perot fiber optic sensor with FBG for the measurement of temperature and strain

NASA Astrophysics Data System (ADS)

Li, L.; Tong, X. L.; Zhou, C. M.; Wen, H. Q.; Lv, D. J.; Ling, K.; Wen, C. S.

2011-03-01

A sensor has been fabricated by the integration of a fiber Bragg gating sensor (FBGs) with a fiber Fabry-Perot (F-P) sensor fabricated by etching method. In the integrated sensor, the FBG was used to measure temperature, while the fiber Fabry-Perot interferometer sensor (FFPIs) was used for strain measurement. Wavelength decoding for FBG and peak tracking for FFPI was employed for demodulation, respectively. The result showed that the temperature and strain sensitivity for the integrated sensor is ~ 2.7 pm/ μɛand ~ 9.3 pm/°C, respectively.

Swept optical SSB-SC modulation technique for high-resolution large-dynamic-range static strain measurement using FBG-FP sensors.

PubMed

Huang, Wenzhu; Zhang, Wentao; Li, Fang

2015-04-01

This Letter presents a static strain demodulation technique for FBG-FP sensors using a suppressed carrier LiNbO(3) (LN) optical single sideband (SSB-SC) modulator. A narrow-linewidth tunable laser source is generated by driving the modulator using a linear chirp signal. Then this tunable single-frequency laser is used to interrogate the FBG-FP sensors with the Pound-Drever-Hall (PDH) technique, which is beneficial to eliminate the influence of light intensity fluctuation of the modulator at different tuning frequencies. The static strain is demodulated by calculating the wavelength difference of the PDH signals between the sensing FBG-FP sensor and the reference FBG-FP sensor. As an experimental result using the modulator, the linearity (R²) of the time-frequency response increases from 0.989 to 0.997, and the frequency-swept range (dynamic range) increases from hundreds of MHz to several GHz compared with commercial PZT-tunable lasers. The high-linearity time-wavelength relationship of the modulator is beneficial for improving the strain measurement resolution, as it can solve the problem of the frequency-swept nonlinearity effectively. In the laboratory test, a 0.67 nanostrain static strain resolution, with a 6 GHz dynamic range, is demonstrated.

A High-Resolution Demodulation Algorithm for FBG-FP Static-Strain Sensors Based on the Hilbert Transform and Cross Third-Order Cumulant

PubMed Central

Huang, Wenzhu; Zhen, Tengkun; Zhang, Wentao; Zhang, Fusheng; Li, Fang

2015-01-01

Static strain can be detected by measuring a cross-correlation of reflection spectra from two fiber Bragg gratings (FBGs). However, the static-strain measurement resolution is limited by the dominant Gaussian noise source when using this traditional method. This paper presents a novel static-strain demodulation algorithm for FBG-based Fabry-Perot interferometers (FBG-FPs). The Hilbert transform is proposed for changing the Gaussian distribution of the two FBG-FPs’ reflection spectra, and a cross third-order cumulant is used to use the results of the Hilbert transform and get a group of noise-vanished signals which can be used to accurately calculate the wavelength difference of the two FBG-FPs. The benefit by these processes is that Gaussian noise in the spectra can be suppressed completely in theory and a higher resolution can be reached. In order to verify the precision and flexibility of this algorithm, a detailed theory model and a simulation analysis are given, and an experiment is implemented. As a result, a static-strain resolution of 0.9 nε under laboratory environment condition is achieved, showing a higher resolution than the traditional cross-correlation method. PMID:25923938

A High-Resolution Demodulation Algorithm for FBG-FP Static-Strain Sensors Based on the Hilbert Transform and Cross Third-Order Cumulant.

PubMed

Huang, Wenzhu; Zhen, Tengkun; Zhang, Wentao; Zhang, Fusheng; Li, Fang

2015-04-27

Static strain can be detected by measuring a cross-correlation of reflection spectra from two fiber Bragg gratings (FBGs). However, the static-strain measurement resolution is limited by the dominant Gaussian noise source when using this traditional method. This paper presents a novel static-strain demodulation algorithm for FBG-based Fabry-Perot interferometers (FBG-FPs). The Hilbert transform is proposed for changing the Gaussian distribution of the two FBG-FPs' reflection spectra, and a cross third-order cumulant is used to use the results of the Hilbert transform and get a group of noise-vanished signals which can be used to accurately calculate the wavelength difference of the two FBG-FPs. The benefit by these processes is that Gaussian noise in the spectra can be suppressed completely in theory and a higher resolution can be reached. In order to verify the precision and flexibility of this algorithm, a detailed theory model and a simulation analysis are given, and an experiment is implemented. As a result, a static-strain resolution of 0.9 nε under laboratory environment condition is achieved, showing a higher resolution than the traditional cross-correlation method.

Polymer-coated FBG sensor for simultaneous temperature and strain monitoring in composite materials under cryogenic conditions.

PubMed

Sampath, Umesh; Kim, Daegil; Kim, Hyunjin; Song, Minho

2018-01-20

A polymer-coated fiber Bragg grating (PCFBG) is examined for real-time temperature and strain monitoring in composite materials at cryogenic temperatures. The proposed sensor enables the simultaneous measurement of temperature and strain at extremely low temperatures by tracking the changes in the reflected center wavelengths from a pair of PCFBGs embedded in a composite material. The cryogenic temperature sensing was realized by introducing polymer coatings onto bare FBGs, which resulted in high temperature sensitivity under cryogenic conditions. A comparison of wavelength responses of the Bragg grating with and without a polymer coating toward temperatures ranging from 25°C to -180°C was performed. The polymer-coated FBG exhibited a sensitivity of 48 pm/°C, which is 10 times greater than that of the bare FBGs. In addition, the encapsulation of the FBG in a capillary tube made it possible to evaluate the strain accumulated within the composite during operation under cryogenic conditions.

Smart FBG-based FRP anchor

NASA Astrophysics Data System (ADS)

Zhou, Zhi; Zhang, Zhichun; Wang, Chuan; Ou, Jinping

2006-03-01

FRP ( Fiber Reinforced Polymer ) has become the popular material to alternate steel in civil engineering under harsh corrosion environment. But due to its low shear strength ability, the anchor for FRP is most important for its practical application. However, the strain state of the surface between FRP and anchor is not fully understood due to that there is no proper sensor to monitor the inner strain in the anchor by traditional method. In this paper, a new smart FBG-based FRP anchor is brought forward, and the inner strain distribution of FRP anchor has been monitored using FRP-OFBG sensors, a smart FBG-embedded FRP rebar, which is pre-embedded in the FRP rod and cast in the anchor. Based on the strain distribution information the bonding shear stress on the surface of FRP rod along the anchor can also be obtained. This method can supply important information for FRP anchor design and can also monitor the anchorage system, which is useful for the application of FRP in civil engineering. The experimental results also show that the smart FBG-based FRP anchor can give direct information of the load and damage of the FRP anchor.

Glue-induced birefringence in surface-attached FBG strain sensors

NASA Astrophysics Data System (ADS)

Helminger, Dominik; Daitche, Alexej; Roths, Johannes

2014-05-01

The influence of the gluing process on the birefringence of surface-glued FBGs that were inscribed in highly birefringence (HiBi) optical fibers of type Panda was studied by monitoring the variation of the birefringence during the gluing procedure. The isothermal curing process at 100°C of the epoxy-based adhesive is characterized by the reduction of birefringence during curing. Significant transversal strain is introduced into the fiber during the cool down period, which is due to different thermal expansion coefficients of the silica and the glue. When the slow axis of the HiBi fiber is oriented parallel to the surface, the glue-induced transversal strain reduces the birefringence of the fiber by ΔB = -6.6 10-5 and when it is perpendicular to the surface, it is increased by ΔB = 1.1 10-5. It can be estimated that for conventional FBGs in single mode fibers a glue-induced birefringence in the order of ΔB = 3.4 10-5 can be expected, which has to be taken into account if in surface-mounted FBG-based strain measurements a high accuracy has to be achieved.

Measurement accuracy of FBG used as a surface-bonded strain sensor installed by adhesive.

PubMed

Xue, Guangzhe; Fang, Xinqiu; Hu, Xiukun; Gong, Libin

2018-04-10

Material and dimensional properties of surface-bonded fiber Bragg gratings (FBGs) can distort strain measurement, thereby lowering the measurement accuracy. To accurately assess measurement precision and correct obtained strain, a new model, considering reinforcement effects on adhesive and measured object, is proposed in this study, which is verified to be accurate enough by the numerical method. Meanwhile, a theoretical strain correction factor is obtained, which is demonstrated to be significantly sensitive to recoating material and bonding length, as suggested by numerical and experimental results. It is also concluded that a short grating length as well as a thin but large-area (preferably covering the whole FBG) adhesive can enhance the correction precision.

Identification of modal strains using sub-microstrain FBG data and a novel wavelength-shift detection algorithm

NASA Astrophysics Data System (ADS)

Anastasopoulos, Dimitrios; Moretti, Patrizia; Geernaert, Thomas; De Pauw, Ben; Nawrot, Urszula; De Roeck, Guido; Berghmans, Francis; Reynders, Edwin

2017-03-01

The presence of damage in a civil structure alters its stiffness and consequently its modal characteristics. The identification of these changes can provide engineers with useful information about the condition of a structure and constitutes the basic principle of the vibration-based structural health monitoring. While eigenfrequencies and mode shapes are the most commonly monitored modal characteristics, their sensitivity to structural damage may be low relative to their sensitivity to environmental influences. Modal strains or curvatures could offer an attractive alternative but current measurement techniques encounter difficulties in capturing the very small strain (sub-microstrain) levels occurring during ambient, or operational excitation, with sufficient accuracy. This paper investigates the ability to obtain sub-microstrain accuracy with standard fiber-optic Bragg gratings using a novel optical signal processing algorithm that identifies the wavelength shift with high accuracy and precision. The novel technique is validated in an extensive experimental modal analysis test on a steel I-beam which is instrumented with FBG sensors at its top and bottom flange. The raw wavelength FBG data are processed into strain values using both a novel correlation-based processing technique and a conventional peak tracking technique. Subsequently, the strain time series are used for identifying the beam's modal characteristics. Finally, the accuracy of both algorithms in identification of modal characteristics is extensively investigated.

Study on dynamic response measurement of the submarine pipeline by full-term FBG sensors.

PubMed

Zhou, Jinghai; Sun, Li; Li, Hongnan

2014-01-01

The field of structural health monitoring is concerned with accurately and reliably assessing the integrity of a given structure to reduce ownership costs, increase operational lifetime, and improve safety. In structural health monitoring systems, fiber Bragg grating (FBG) is a promising measurement technology for its superior ability of explosion proof, immunity to electromagnetic interference, and high accuracy. This paper is a study on the dynamic characteristics of fiber Bragg grating (FBG) sensors applied to a submarine pipeline, as well as an experimental investigation on a laboratory model of the pipeline. The dynamic response of a submarine pipeline under seismic excitation is a coupled vibration of liquid and solid interaction. FBG sensors and strain gauges are used to monitor the dynamic response of a submarine pipeline model under a variety of dynamic loading conditions and the maximum working frequency of an FBG strain sensor is calculated according to its dynamic strain responses. Based on the theoretical and experimental results, it can be concluded that FBG sensor is superior to strain gauge and satisfies the demand of dynamic strain measurement.

Study on Dynamic Response Measurement of the Submarine Pipeline by Full-Term FBG Sensors

PubMed Central

Zhou, Jinghai; Sun, Li; Li, Hongnan

2014-01-01

The field of structural health monitoring is concerned with accurately and reliably assessing the integrity of a given structure to reduce ownership costs, increase operational lifetime, and improve safety. In structural health monitoring systems, fiber Bragg grating (FBG) is a promising measurement technology for its superior ability of explosion proof, immunity to electromagnetic interference, and high accuracy. This paper is a study on the dynamic characteristics of fiber Bragg grating (FBG) sensors applied to a submarine pipeline, as well as an experimental investigation on a laboratory model of the pipeline. The dynamic response of a submarine pipeline under seismic excitation is a coupled vibration of liquid and solid interaction. FBG sensors and strain gauges are used to monitor the dynamic response of a submarine pipeline model under a variety of dynamic loading conditions and the maximum working frequency of an FBG strain sensor is calculated according to its dynamic strain responses. Based on the theoretical and experimental results, it can be concluded that FBG sensor is superior to strain gauge and satisfies the demand of dynamic strain measurement. PMID:24971391

Investigation on Characteristic Variation of the FBG Spectrum with Crack Propagation in Aluminum Plate Structures

PubMed Central

Jin, Bo; Zhang, Weifang; Zhang, Meng; Ren, Feifei; Dai, Wei; Wang, Yanrong

2017-01-01

In order to monitor the crack tip propagation of aluminum alloy, this study investigates the variation of the spectrum characteristics of a fiber Bragg grating (FBG), combined with an analysis of the spectrum simulation. The results identify the location of the subordinate peak as significantly associated with the strain distribution along the grating, corresponding to the different plastic zones ahead of the crack tip with various crack lengths. FBG sensors could observe monotonic and cyclic plastic zones ahead of the crack tip, with the quadratic strain distribution along the grating at the crack tip-FBG distance of 1.2 and 0.7 mm, respectively. FBG sensors could examine the process zones ahead of the crack tip with the cubic strain distribution along the grating at the crack tip-FBG distance of 0.5 mm. The spectrum oscillation occurs as the crack approaches the FBG where the highly heterogeneous strain is distributed. Another idea is to use a finite element method (FEM), together with a T-matrix method, to analyze the reflection intensity spectra of FBG sensors for various crack sizes. The described crack propagation detection system may apply in structural health monitoring. PMID:28772949

Investigation on Characteristic Variation of the FBG Spectrum with Crack Propagation in Aluminum Plate Structures.

PubMed

Jin, Bo; Zhang, Weifang; Zhang, Meng; Ren, Feifei; Dai, Wei; Wang, Yanrong

2017-05-27

In order to monitor the crack tip propagation of aluminum alloy, this study investigates the variation of the spectrum characteristics of a fiber Bragg grating (FBG), combined with an analysis of the spectrum simulation. The results identify the location of the subordinate peak as significantly associated with the strain distribution along the grating, corresponding to the different plastic zones ahead of the crack tip with various crack lengths. FBG sensors could observe monotonic and cyclic plastic zones ahead of the crack tip, with the quadratic strain distribution along the grating at the crack tip-FBG distance of 1.2 and 0.7 mm, respectively. FBG sensors could examine the process zones ahead of the crack tip with the cubic strain distribution along the grating at the crack tip-FBG distance of 0.5 mm. The spectrum oscillation occurs as the crack approaches the FBG where the highly heterogeneous strain is distributed. Another idea is to use a finite element method (FEM), together with a T -matrix method, to analyze the reflection intensity spectra of FBG sensors for various crack sizes. The described crack propagation detection system may apply in structural health monitoring.

Self-Evaluation of PANDA-FBG Based Sensing System for Dynamic Distributed Strain and Temperature Measurement.

PubMed

Zhu, Mengshi; Murayama, Hideaki; Wada, Daichi

2017-10-12

A novel method is introduced in this work for effectively evaluating the performance of the PANDA type polarization-maintaining fiber Bragg grating (PANDA-FBG) distributed dynamic strain and temperature sensing system. Conventionally, the errors during the measurement are unknown or evaluated by using other sensors such as strain gauge and thermocouples. This will make the sensing system complicated and decrease the efficiency since more than one kind of sensor is applied for the same measurand. In this study, we used the approximately constant ratio of primary errors in strain and temperature measurement and realized the self-evaluation of the sensing system, which can significantly enhance the applicability, as well as the reliability in strategy making.

A cost-effective edge-filter-based FBG strain interrogator using catastrophic fuse effect microcavity interferometers

NASA Astrophysics Data System (ADS)

Díaz, Camilo A. R.; Marques, Carlos A. F.; Domingues, M. Fátima F.; Ribeiro, Moisés. R. N.; Neto, Anselmo F.; Pontes, Maria J.; André, Paulo S.; Antunes, Paulo F. C.

2018-02-01

This paper presents a simple, compact, stable and inexpensive in-line solution based on catastrophic fuse effect micro-cavity interferometers for edge-filter strain interrogation of a fiber Bragg grating sensor. By using a commercial spliced machine and recycling damage fiber for the catastrophic fuse effect it is possible to construct a micro-cavity with high contrast of more than 20dB, and acceptable half free spectra range (FSR) around 13nm of interrogation range. The strain from 0 to 1440μStrain of the FBG sensor is measured with evidences of high repeatability and stability. Future work will investigate the use of the proposed method for applications requiring higher interrogation rates.

Performance of a distributed simultaneous strain and temperature sensor based on a Fabry-Perot laser diode and a dual-stage FBG optical demultiplexer.

PubMed

Kim, Suhwan; Kwon, Hyungwoo; Yang, Injae; Lee, Seungho; Kim, Jeehyun; Kang, Shinwon

2013-11-12

A simultaneous strain and temperature measurement method using a Fabry-Perot laser diode (FP-LD) and a dual-stage fiber Bragg grating (FBG) optical demultiplexer was applied to a distributed sensor system based on Brillouin optical time domain reflectometry (BOTDR). By using a Kalman filter, we improved the performance of the FP-LD based OTDR, and decreased the noise using the dual-stage FBG optical demultiplexer. Applying the two developed components to the BOTDR system and using a temperature compensating algorithm, we successfully demonstrated the simultaneous measurement of strain and temperature distributions under various experimental conditions. The observed errors in the temperature and strain measured using the developed sensing system were 0.6 °C and 50 με, and the spatial resolution was 1 m, respectively.

Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope.

PubMed

Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

2017-03-15

By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes.

Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope

PubMed Central

Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

2017-01-01

By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes. PMID:28294995

Distributed FBG sensors apply in spacecraft health monitoring

NASA Astrophysics Data System (ADS)

Huang, Xiujun; Zhang, Cuicui; Shi, Dele; Shen, Jingshi

2017-10-01

At present, Spacecraft manufacturing face with high adventure for its complicate structure, serious space environment and not maintained on orbit. When something wrong with spacecraft, monitoring its health state, supply health data in real time would assure quickly locate error and save more time to rescue it. For FBG sensor can distributed test several parameters such as temperature, strain, vibration and easily construct net. At same time, it has more advantages such as ant-radiate, anti-jamming, rodent-resistant and with long lifetime, which more fit for applying in space. In this paper, a spacecraft health monitor system based on FBG sensors is present, Firstly, spacecraft health monitor system and its development are introduced. Then a four channels FBG demodulator is design. At last, Temperature and strain detecting experiment is done. The result shows that the demodulator fully satisfied the need of spacecraft health monitor system.

Structural health monitoring of cylindrical bodies under impulsive hydrodynamic loading by distributed FBG strain measurements

NASA Astrophysics Data System (ADS)

Fanelli, Pierluigi; Biscarini, Chiara; Jannelli, Elio; Ubertini, Filippo; Ubertini, Stefano

2017-02-01

Various mechanical, ocean, aerospace and civil engineering problems involve solid bodies impacting the water surface and often result in complex coupled dynamics, characterized by impulsive loading conditions, high amplitude vibrations and large local deformations. Monitoring in such problems for purposes such as remaining fatigue life estimation and real time damage detection is a technical and scientific challenge of primary concern in this context. Open issues include the need for developing distributed sensing systems able to operate at very high acquisition frequencies, to be utilized to study rapidly varying strain fields, with high resolution and very low noise, while scientific challenges mostly relate to the definition of appropriate signal processing and modeling tools enabling the extraction of useful information from distributed sensing signals. Building on previous work by some of the authors, we propose an enhanced method for real time deformed shape reconstruction using distributed FBG strain measurements in curved bodies subjected to impulsive loading and we establish a new framework for applying this method for structural health monitoring purposes, as the main focus of the work. Experiments are carried out on a cylinder impacting the water at various speeds, proving improved performance in displacement reconstruction of the enhanced method compared to its previous version. A numerical study is then carried out considering the same physical problem with different delamination damages affecting the body. The potential for detecting, localizing and quantifying this damage using the reconstruction algorithm is thoroughly investigated. Overall, the results presented in the paper show the potential of distributed FBG strain measurements for real time structural health monitoring of curved bodies under impulsive hydrodynamic loading, defining damage sensitive features in terms of strain or displacement reconstruction errors at selected locations along

Femtosecond FBG Written through the Coating for Sensing Applications.

PubMed

Habel, Joé; Boilard, Tommy; Frenière, Jean-Simon; Trépanier, François; Bernier, Martin

2017-11-02

Type I fiber Bragg gratings (FBG) written through the coating of various off-the-shelf silica fibers with a femtosecond laser and the phase-mask technique are reported. Inscription through most of the common coating compositions (acrylate, silicone and polyimide) is reported as well as writing through the polyimide coating of various fiber cladding diameters, down to 50 µm. The long term annealing behavior of type I gratings written in a pure silica core fiber is also reported as well as a comparison of the mechanical resistance of type I and II FBG. The high mechanical resistance of the resulting type I FBG is shown to be useful for the fabrication of various distributed FBG arrays written using a single period phase-mask. The strain sensing response of such distributed arrays is also presented.

Spectra analysis of nonuniform FBG-based acousto-optic modulator by using Fourier mode coupling theory.

PubMed

Liu, Chao; Pei, Li; Li, Zhuoxuan; Ning, Tigang; Yu, Shaowei; Kang, Zexin

2013-05-10

Fourier mode coupling theory was first employed in the spectral analysis of several nonuniform fiber Bragg grating (FBG)-based acousto-optic modulators (NU-FBG-AOMs) with the effects of Gaussian-apodization (GA), phase shift (PS), and linear chirp (LC). Because of the accuracy and simplicity of the algorithm applied in this model, the modulation performances of these modulators can be acquired effectively and efficiently. Based on the model, the reflected spectra of these modulators were simulated under various acoustic frequencies and acoustically induced strains. The simulation results of the GA-FBG-AOM and PS-FBG-AOM showed that the wavelength spacing between the primary reflection peak and the secondary reflection peak is proportional to the acoustic frequency, and the reflectivity of reflection peaks depends on the acoustically induced strains. But for the LC-FBG-AOM, the wavelength spacing between the neighboring reflection peaks increased linearly and inversely with the acoustic frequency, and the extinction ratio of each peak relates to the acoustically induced strain. These numerical analysis results, which were effectively used in the designs and fabrications of these NU-FBG-AOMs, can broaden the AOM-based application scope and shed light on the performance optimization of optical wavelength-division multiplex system.

Femtosecond FBG Written through the Coating for Sensing Applications

PubMed Central

Habel, Joé; Boilard, Tommy; Frenière, Jean-Simon; Bernier, Martin

2017-01-01

Type I fiber Bragg gratings (FBG) written through the coating of various off-the-shelf silica fibers with a femtosecond laser and the phase-mask technique are reported. Inscription through most of the common coating compositions (acrylate, silicone and polyimide) is reported as well as writing through the polyimide coating of various fiber cladding diameters, down to 50 µm. The long term annealing behavior of type I gratings written in a pure silica core fiber is also reported as well as a comparison of the mechanical resistance of type I and II FBG. The high mechanical resistance of the resulting type I FBG is shown to be useful for the fabrication of various distributed FBG arrays written using a single period phase-mask. The strain sensing response of such distributed arrays is also presented. PMID:29099077

Monitoring Poisson's Ratio Degradation of FRP Composites under Fatigue Loading Using Biaxially Embedded FBG Sensors.

PubMed

Akay, Erdem; Yilmaz, Cagatay; Kocaman, Esat S; Turkmen, Halit S; Yildiz, Mehmet

2016-09-19

The significance of strain measurement is obvious for the analysis of Fiber-Reinforced Polymer (FRP) composites. Conventional strain measurement methods are sufficient for static testing in general. Nevertheless, if the requirements exceed the capabilities of these conventional methods, more sophisticated techniques are necessary to obtain strain data. Fiber Bragg Grating (FBG) sensors have many advantages for strain measurement over conventional ones. Thus, the present paper suggests a novel method for biaxial strain measurement using embedded FBG sensors during the fatigue testing of FRP composites. Poisson's ratio and its reduction were monitored for each cyclic loading by using embedded FBG sensors for a given specimen and correlated with the fatigue stages determined based on the variations of the applied fatigue loading and temperature due to the autogenous heating to predict an oncoming failure of the continuous fiber-reinforced epoxy matrix composite specimens under fatigue loading. The results show that FBG sensor technology has a remarkable potential for monitoring the evolution of Poisson's ratio on a cycle-by-cycle basis, which can reliably be used towards tracking the fatigue stages of composite for structural health monitoring purposes.

Application of FBG sensors in strengthening and maintenance monitoring of old bridges

NASA Astrophysics Data System (ADS)

Yue, Li-na; Huang, Jun; Yang, Yan

2009-10-01

The various fiber Bragg grating(FBG)sensors such as FBG force rings, differential FBG displacement cells, FBG strain sensors and FBG temperature sensors had been used to monitor the strengthening and maintenance process of the continuous concrete beam bridges and the continuous concrete rigid frame bridges which are the part of Wuhan Second Yangtze River Bridge. In the strengthening and maintenance process, the tension force of the external prestressed tendons, the cracks change and intensity of cross sections had been monitored to insure the instruction safety, study the effect of strengthening and maintenance, and verify the design theories of strengthening and maintenance. Also the reference state criterion for long-term bridge health monitoring had been provided according to the monitoring results.

Monitoring Poisson’s Ratio Degradation of FRP Composites under Fatigue Loading Using Biaxially Embedded FBG Sensors

PubMed Central

Akay, Erdem; Yilmaz, Cagatay; Kocaman, Esat S.; Turkmen, Halit S.; Yildiz, Mehmet

2016-01-01

The significance of strain measurement is obvious for the analysis of Fiber-Reinforced Polymer (FRP) composites. Conventional strain measurement methods are sufficient for static testing in general. Nevertheless, if the requirements exceed the capabilities of these conventional methods, more sophisticated techniques are necessary to obtain strain data. Fiber Bragg Grating (FBG) sensors have many advantages for strain measurement over conventional ones. Thus, the present paper suggests a novel method for biaxial strain measurement using embedded FBG sensors during the fatigue testing of FRP composites. Poisson’s ratio and its reduction were monitored for each cyclic loading by using embedded FBG sensors for a given specimen and correlated with the fatigue stages determined based on the variations of the applied fatigue loading and temperature due to the autogenous heating to predict an oncoming failure of the continuous fiber-reinforced epoxy matrix composite specimens under fatigue loading. The results show that FBG sensor technology has a remarkable potential for monitoring the evolution of Poisson’s ratio on a cycle-by-cycle basis, which can reliably be used towards tracking the fatigue stages of composite for structural health monitoring purposes. PMID:28773901

A new kind of high durable traffic weighbridge based on FBG sensors

NASA Astrophysics Data System (ADS)

Zhou, Zhi; Liu, Jing; Li, Hui; Ou, Jinping

2005-05-01

Durability is the key problem of traditional traffic weighbridge based on electrical gauges. In this paper, a new kind of high durable traffic weighbridge based on FBG (Fiber Bragg Grating) sensors has been studied and developed. The principle of the smart FBG-weighbridge is based on that the traffic weight can be gotten from the deformation of the reinforced concrete beam with embedded FRP (Fiber Reinforced Polymer) - packaged FBG strain sensors. The FBG-based weighbridge is designed to be a reinforced concrete board supported by composite beams, and the truck load is shared by the composite beams. A 30-ton full scale FBG-based weighbridge has been set up, and the results from the tests and calibration analysis show that this kind of weighbridge features high durability, simplicity, convenience, low cost, etc. This new kind of FBG-based weighbridge shows good prospect in future to replace the traditional traffic weighbridge for long-term monitoring of traffic load.

A Low Frequency FBG Accelerometer with Symmetrical Bended Spring Plates.

PubMed

Liu, Fufei; Dai, Yutang; Karanja, Joseph Muna; Yang, Minghong

2017-01-22

To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating) accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal in magnitude but opposite in direction when exciting vibrations exist, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, with which the influence of the structural parameters on the sensitivity and the eigenfrequency are discussed. The test results show that the sensitivity of the accelerometer is more than 1000 pm/g when the frequency is within the 0.7-20 Hz range.

Design, manufacture and testing of an FBG-instrumented composite wing

NASA Astrophysics Data System (ADS)

Abouzeida, E.; Quinones, V.; Gowayed, Y.; Soobramaney, P.; Flowers, G.; Black, R. J.; Costa, J. M.; Faridian, F.; Moslehi, B.

2014-02-01

In this work, our research team investigated the efficacy of using optical static and dynamic strain sensing with embedded Fiber Bragg Gratings (FBGs) in structural health monitoring (SHM) of a model composite airplane wing. A one-fourth scale model of a T38 airplane wing was designed and manufactured using fabric reinforced polymer matrix composites with FBG sensors embedded under the top layer of the composite. The accuracy and durability of the sensors were evaluated at the coupon and structural levels utilizing static and dynamic testing. Strain measurements using embedded FBGs with an optical interrogator were found to be in agreement with values measured using other strain measuring devices and with results obtained using finite element analysis (ANSYS®). Preferred locations for the FBG sensors were identified in accordance with contour maps of internal strain distributions resulting from critical load cases. Manufacturing techniques used to address handling, survivability and durability of the embedded sensors during and post manufacturing of the composites were evaluated and optimized.

A Monitoring Method Based on FBG for Concrete Corrosion Cracking.

PubMed

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-07-14

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure.

A Monitoring Method Based on FBG for Concrete Corrosion Cracking

PubMed Central

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-01-01

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure. PMID:27428972

Miniature fiber Bragg grating sensor interrogator (FBG-Transceiver) system

NASA Astrophysics Data System (ADS)

Mendoza, Edgar A.; Kempen, Cornelia; Lopatin, Craig

2007-04-01

This paper describes recent progress conducted towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-Transceiver TM) system based on multi-channel integrated optic sensor (InOSense TM) microchip technology. The hybrid InOSense TM microchip technology enables the integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogator systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation. The FBG-Transceiver system uses active optoelectronic components monolithically integrated to the InOSense TM microchip, a microprocessor controlled signal processing electronics board capable of processing the FBG sensors signals related to stress-strain and temperature as well as vibration and acoustics. The FBG-Transceiver TM system represents a new, reliable, highly robust technology that can be used to accurately monitor the status of an array of distributed fiber optic Bragg grating sensors installed in critical infrastructures. Its miniature package, low power operation, and state-of-the-art data communications architecture, all at a very affordable price makes it a very attractive solution for a large number of SHM/NDI applications in aerospace, naval and maritime industry, civil structures like bridges, buildings and dams, the oil and chemical industry, and for homeland security applications. The miniature, cost-efficient FBG-Transceiver TM system is poised to revolutionize the field of structural health monitoring and nondestructive inspection market. The sponsor of this program is NAVAIR under a DOD SBIR contract.

Prototype fiber Bragg Grattings (FBG) sensor based on intensity modulation of the laser diode low frequency vibrations measurement

NASA Astrophysics Data System (ADS)

Setiono, Andi; Ula, Rini Khamimatul; Hanto, Dwi; Widiyatmoko, Bambang; Purnamaningsih, Retno Wigajatri

2016-02-01

In general, Fiber Bragg Grating (FBG) sensor works based on observation of spectral response characteristic to detect the desired parameter. In this research, we studied intensity response characteristic of FBG to detect the dynamic strain. Experiment result show that the reflected intensity had linier relationships with dynamic strain. Based on these characteristics, we developed the FBG sensor to detect low frequency vibration. This sensor is designed by attaching the FBG on the bronze cantilever with dimensions of 85×3×0.5 mm. Measurement results showed that the sensor was able to detect vibrations in the frequency range of 7-10 Hz at temperature range of 25-45 ˚C. The measured frequency range is still within the frequency range of digging activity, therefore this vibration sensor can be applied for oil pipelines vandalisation detection system.

A short baseline strainmeter using fiber-optic Bragg-Grating (FBG) sensor and a nano-optic interferometer

NASA Astrophysics Data System (ADS)

Coutant, O.; Demengin, M.; Le Coarer, E.; Gaffet, S.

2013-12-01

Strain recordings from tiltmeters or borehole volumetric strainmeters on volcanoes reveal extremely rich signal of deformation associated with eruptive processes. The ability to detect and record signals of the order of few tens of nanostrain is complementary to other monitoring techniques, and of great interest to monitor and model the volcanic processes. Strain recording remains however a challenge, for both the instrumental and the installation point of view. We present in this study the first results of strain recordings, using a new fiber-optic Bragg-Grating (FBG) sensor. FBG sensors are known for many years and used as strain gauges in civil engineering. They are however limited in this case to microstrain capability. We use here a newly developped interferometer named SWIFTS whose main characteristics are i) an extremely high optical wavelength precision and ii) a small design and low power requirements allowing an easy field deployment. Our FBG sensor uses a short baseline, 3cm long Bragg network. We show preliminary results obtained from a several months recordings in the low noise underground laboratory at Rustrel (LSBB), south of France.

Damage Detection Based on Static Strain Responses Using FBG in a Wind Turbine Blade.

PubMed

Tian, Shaohua; Yang, Zhibo; Chen, Xuefeng; Xie, Yong

2015-08-14

The damage detection of a wind turbine blade enables better operation of the turbines, and provides an early alert to the destroyed events of the blade in order to avoid catastrophic losses. A new non-baseline damage detection method based on the Fiber Bragg grating (FBG) in a wind turbine blade is developed in this paper. Firstly, the Chi-square distribution is proven to be an effective damage-sensitive feature which is adopted as the individual information source for the local decision. In order to obtain the global and optimal decision for the damage detection, the feature information fusion (FIF) method is proposed to fuse and optimize information in above individual information sources, and the damage is detected accurately through of the global decision. Then a 13.2 m wind turbine blade with the distributed strain sensor system is adopted to describe the feasibility of the proposed method, and the strain energy method (SEM) is used to describe the advantage of the proposed method. Finally results show that the proposed method can deliver encouraging results of the damage detection in the wind turbine blade.

Damage Detection Based on Static Strain Responses Using FBG in a Wind Turbine Blade

PubMed Central

Tian, Shaohua; Yang, Zhibo; Chen, Xuefeng; Xie, Yong

2015-01-01

The damage detection of a wind turbine blade enables better operation of the turbines, and provides an early alert to the destroyed events of the blade in order to avoid catastrophic losses. A new non-baseline damage detection method based on the Fiber Bragg grating (FBG) in a wind turbine blade is developed in this paper. Firstly, the Chi-square distribution is proven to be an effective damage-sensitive feature which is adopted as the individual information source for the local decision. In order to obtain the global and optimal decision for the damage detection, the feature information fusion (FIF) method is proposed to fuse and optimize information in above individual information sources, and the damage is detected accurately through of the global decision. Then a 13.2 m wind turbine blade with the distributed strain sensor system is adopted to describe the feasibility of the proposed method, and the strain energy method (SEM) is used to describe the advantage of the proposed method. Finally results show that the proposed method can deliver encouraging results of the damage detection in the wind turbine blade. PMID:26287200

A MHz speed wavelength sweeping for ultra-high speed FBG interrogation

NASA Astrophysics Data System (ADS)

Kim, Gyeong Hun; Lee, Hwi Don; Eom, Tae Joong; Jeong, Myung Yung; Kim, Chang-Seok

2015-09-01

We demonstrated a MHz speed wavelength-swept fiber laser based on the active mode locking (AML) technique and applied to interrogation system of an array of fiber Bragg grating (FBG) sensors. MHz speed wavelength sweeping of wavelength-swept fiber laser can be obtained by programmable frequency modulation of the semiconductor optical amplifier (SOA) without any wavelength tunable filter. Both static and dynamic strain measurement of FBG sensors were successfully characterized with high linearity of an R-square value of 0.9999 at sweeping speed of 50 kHz.

FBG based high sensitive pressure sensor and its low-cost interrogation system with enhanced resolution

NASA Astrophysics Data System (ADS)

Pachava, Vengal Rao; Kamineni, Srimannarayana; Madhuvarasu, Sai Shankar; Putha, Kishore; Mamidi, Venkata Reddy

2015-12-01

A fiber Bragg grating (FBG) pressure sensor with high sensitivity and resolution has been designed and demonstrated. The sensor is configured by firmly fixing the FBG with a metal bellows structure. The sensor works by means of measuring the Bragg wavelength shift of the FBG with respect to pressure change. From the experimental results, the pressure sensitivity of the sensor is found to be 90.6 pm/psi, which is approximately 4000 times as that of a bare fiber Bragg grating. A very good linearity of 99.86% is observed between the Bragg wavelength of the FBG and applied pressure. The designed sensor shows good repeatability with a negligible hysteresis error of ± 0.29 psi. A low-cost interrogation system that includes a long period grating (LPG) and a photodiode (PD) accompanied with simple electronic circuitry is demonstrated for the FBG sensor, which enables the sensor to attain high resolution of up to 0.025 psi. Thermal-strain cross sensitivity of the FBG pressure sensor is compensated using a reference FBG temperature sensor. The designed sensor can be used for liquid level, specific gravity, and static/dynamic low pressure measurement applications.

Test of FBG sensors for monitoring high pressure pipes

NASA Astrophysics Data System (ADS)

Paolozzi, Antonio; Paris, Claudio; Vendittozzi, Cristian; Felli, Ferdinando; Mongelli, Marialuisa; De Canio, Gerardo; Colucci, Alessandro; Asanuma, Hiroshi

2017-04-01

Fibre Bragg Grating (FBG) sensors are increasingly being used on a wide range of civil, industrial and aerospace structures. The sensors are created inside optical fibres (usually standard telecommunication fibres); the optical fibres technology allows to install the sensors on structures working in harsh environments, since the materials are almost insensitive to corrosion, the monitoring system can be positioned far away from the sensors without sensible signal losses, and there is no risk of electric discharge. FBG sensors can be used to create strain gages, thermometers or accelerometers, depending on the coating on the grating, on the way the grating is fixed to the structure, and on the presence of a specifically designed interface that can act as a transducer. This paper describes a test of several different FBG sensors to monitor an high pressure pipe that feeds the hydraulic actuators of a 6 degrees-of-freedom shaking table at the ENEA Casaccia research centre. A bare FBG sensor and a copper coated FBG sensor have been glued on the pipe. A third sensor has been mounted on a special interface to amplify the vibrations; this last sensor can be placed on the steel pipe by a magnetic mounting system, that also allows the its removal. All the sensor are placed parallel to the axis of the pipe. The analysis of the data recorded when the shaking table is operated will allow to determine which kind of sensor is best suited for structural monitoring of high pressure pipelines.

A cost effective FBG-based security fence with fire alarm function

NASA Astrophysics Data System (ADS)

Wu, H. J.; Li, S. S.; Lu, X. L.; Wu, Y.; Rao, Y. J.

2012-02-01

Fiber Bragg Grating (FBG) is sensitive to the temperature as well when it is measuring the strain change, which is always avoided in most measurement applications. However, in this paper strain/temperature dual sensitivity is utilized to construct a special security fence with a second function of fire threat prediction. In an FBG-based fiber fence configuration, only by characteristics analysis and identification method, it can intelligently distinguish the different effects of personal threats and fires from their different trends of the wavelength drifts. Thus without any additional temperature sensing fittings or other fire alarm systems integrated, a normal perimeter security system can possess a second function of fire prediction, which can not only monitor the intrusion induced by personal actions but also predict fire threats in advance. The experimental results show the effectiveness of the method.

Biaxial strain in graphene adhered to shallow depressions.

PubMed

Metzger, Constanze; Rémi, Sebastian; Liu, Mengkun; Kusminskiy, Silvia V; Castro Neto, Antonio H; Swan, Anna K; Goldberg, Bennett B

2010-01-01

Measurements on graphene exfoliated over a substrate prepatterned with shallow depressions demonstrate that graphene does not remain free-standing but instead adheres to the substrate despite the induced biaxial strain. The strain is homogeneous over the depression bottom as determined by Raman measurements. We find higher Raman shifts and Gruneisen parameters of the phonons underlying the G and 2D bands under biaxial strain than previously reported. Interference modeling is used to determine the vertical position of the graphene and to calculate the optimum dielectric substrate stack for maximum Raman signal.

FBG sensor for temperature-independent high sensitive pressure measurement with aid of a Bourdon tube

NASA Astrophysics Data System (ADS)

Srimannarayana, K.; Vengal Rao, P.; Sai Shankar, M.; Kishore, P.

2014-05-01

A temperature independent high sensitive pressure sensing system using fiber Bragg grating (FBG) and `C' shaped Bourdon tube (CBT) is demonstrated. The sensor is configured by firmly fixing the FBG (FBG1) between free and fixed ends of the CBT. Additional FBG (FBG2) in line to the FBG1 is introduced which is shielded from the external pressure, tend to measure only the ambient temperature fluctuations. The CBT has an elliptical cross section where its free end is sealed and the fixed end is open for subjecting the liquid or gas pressure to be measured. With the application of pressure, the free end of CBT tends to straighten out results in an axial strain in FBG1 causes red shift in Bragg wavelength. The pressure can be determined by measuring the shift of the Bragg wavelength. The experimental pressure sensitivity is found to be 66.9 pm/psi over a range of 0 to 100 psi. The test results show that the Bragg wavelength shift is linear corresponds to change in applied pressure and well agreed with the simulated results. This simple and high sensitive design is capable of measuring static/dynamic pressure and temperature simultaneously which suits for industrial applications.

DFB fiber laser static strain sensor based on beat frequency interrogation with a reference fiber laser locked to a FBG resonator.

PubMed

Huang, Wenzhu; Feng, Shengwen; Zhang, Wentao; Li, Fang

2016-05-30

We report on a high-resolution static strain sensor developed with distributed feedback (DFB) fiber laser. A reference FBG resonator is used for temperature compensation. Locking another independent fiber laser to the resonator using the Pound-Drever-Hall technique results in a strain power spectral density better than S_ε(f) = (4.6 × 10^-21) ε²/Hz in the frequency range from 1 Hz to 1 kHz, corresponding to a minimum dynamic strain resolution of 67.8 pε/√Hz. This frequency stabilized fiber laser is proposed to interrogate the sensing DFB fiber laser by the beat frequency principle. As a reasonable DFB fiber laser setup is realized, a narrow beat frequency line-width of 3.23 kHz and a high beat frequency stability of 0.036 MHz in 15 minutes are obtained in the laboratory test, corresponding to a minimum static strain resolution of 270 pε. This is the first time that a sub-0.5 nε level for static strain measurement using DFB fiber laser is demonstrated.

Haemophilus parasuis serovar 5 Nagasaki strain adheres and invades PK-15 cells.

PubMed

Frandoloso, Rafael; Martínez-Martínez, Sonia; Gutiérrez-Martín, César B; Rodríguez-Ferri, Elías F

2012-01-27

Haemophilus parasuis is the agent responsible for causing Glässer's disease, which is characterized by fibrinous polyserositis, polyarthritis and meningitis in pigs. The purpose of this study was to investigate the in vitro ability of two H. parasuis serovars of different virulence (serovar 5, Nagasaki strain, highly virulent, belonging to serovar 5, and SW114 strain, nonvirulent, belonging to serovar 3) to adhere to and invade porcine kidney epithelial cells (PK-15 line). Nagasaki strain was able to attach at high levels from 60 to 180 min of incubation irrespective of the concentrations compared (10(7)-10(10)CFU), and a substantial increase of surface projections could be seen in PK-15 cells by scanning electron microscopy. This virulent strain was also able to invade effectively these epithelial cells, and the highest invasion capacity was reached at 180 min of infection. On the contrary, nonvirulent SW114 strain hardly adhered to PK-15 cells, and it did not invade these cells, thus suggesting that adherence and invasion of porcine kidney epithelial cells could be a virulence mechanism involved in the lesions caused by H. parasuis Nagasaki strain in this organ. Copyright © 2011 Elsevier B.V. All rights reserved.

Use of FBG sensors for health monitoring of pipelines

NASA Astrophysics Data System (ADS)

Felli, Ferdinando; Paolozzi, Antonio; Vendittozzi, Cristian; Paris, Claudio; Asanuma, Hiroshi

2016-04-01

The infrastructures for oil and gas production and distribution need reliable monitoring systems. The risks for pipelines, in particular, are not only limited to natural disasters (landslides, earthquakes, extreme environmental conditions) and accidents, but involve also the damages related to criminal activities, such as oil theft. The existing monitoring systems are not adequate for detecting damages from oil theft, and in several occasion the illegal activities resulted in leakage of oil and catastrophic environmental pollution. Systems based on fiber optic FBG (Fiber Bragg Grating) sensors present a number of advantages for pipeline monitoring. FBG sensors can withstand harsh environment, are immune to interferences, and can be used to develop a smart system for monitoring at the same time several physical characteristics, such as strain, temperature, acceleration, pressure, and vibrations. The monitoring station can be positioned tens of kilometers away from the measuring points, lowering the costs and the complexity of the system. This paper describes tests on a sensor, based on FBG technology, developed specifically for detecting damages of pipeline due to illegal activities (drilling of the pipes), that can be integrated into a smart monitoring chain.

Application of fiber Bragg grating sensors to real-time strain measurement of cryogenic tanks

NASA Astrophysics Data System (ADS)

Takeda, Nobuo; Mizutani, Tadahito; Hayashi, Kentaro; Okabe, Yoji

2003-08-01

Although many researches of strain measurement using fiber Bragg grating (FBG) sensors were conducted, there were few applications of FBG sensors to spacecraft in operation. It is very significant to develop an onboard system for the real-time strain measurement during the flight operation. In the present research, the real-time strain measurement of a composite liquid hydrogen (LH2) tank, which consisted of CFRP and aluminum liner, was attempted. Adhesive property of the FBG sensors was investigated first of all. As a result, UV coated FBG sensors and polyurethane adhesive were adopted. Then, reflection spectra from FBG sensors were measured through the tensile test at liquid helium (LHe) temperature. Since the center wavelength shifted in proportion to the applied strain, the FBG sensor was suitable as a precise strain sensor even at LHe temperature. Next, the development of an onboard FBG demodulator was discussed. This onboard demodulator was designed for weight saving to be mounted on a reusable rocket vehicle test (RVT) operated by the Institute of Space and Astronautical Science (ISAS). FBG sensors were bonded on the surface of the composite LH2 tank for the RVT. Then, strain measurement using the onboard demodulator was conducted through the cryogenic pressure test of the tank and compared with the result measured using the optical spectrum analyzer (OSA).

The characteristic of gap FBG and its application

NASA Astrophysics Data System (ADS)

Yang, Yuanhong; Hu, Jun; Liu, Xuejing; Jin, Wei

2015-07-01

A gap fiber Bragg grating (g-FBG) is fabricated by cutting a uniform FBG in the middle to introduce a small air gap between the two sections. Numerical and experimental investigations show that the g-FBG has the characteristics of both a phase shifted FBG and a Fizeau interferometer. The influence of the air-gap shift longitudinally or transversely with respect to the fiber central axis and temperature to g-FBG's spectrums are investigated with numerical simulation and experiments, and the mathematic models are made. Based on g-FBG's different sensitivity to gap width and temperature, a micro-gap and temperature simultaneous measurement sensor was demonstrated. And a g-FBG based tunable fiber ring laser with a narrow line-width is demonstrated.

Early-age monitoring of cement structures using FBG sensors

NASA Astrophysics Data System (ADS)

Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

2006-03-01

With more and more broad applications of the cement-based structures such as neat cement paste, cement mortar and concrete in civil engineering, people hope to find out what their performances should like. The in-service performances of cement-based structures are highly affected by their hardening process during the early-age. But it is still a big problem for traditional sensors to be used to monitor the early curing of cement-based structures due to such disadvantages as difficulties to install sensors inside the concrete, limited measuring points, poor durability and interference of electromagnetic wave and so on. In this paper, according to the sensing properties of the Fiber Bragg Grating sensors and self-characters of the cement-based structures, we have successfully finished measuring and monitoring the early-age inner-strain and temperature changes of the neat cement paste, concrete with and without restrictions, mass concrete structures and negative concrete, respectively. Three types of FBG-based sensors have been developed to monitor the cement-based structures. Besides, the installation techniques and the embedding requirements of FBG sensors in cement-based structures are also discussed. Moreover, such kind of technique has been used in practical structure, 3rd Nanjing Yangtze Bridge, and the results show that FBG sensors are well proper for measuring and monitoring the temperature and strain changes including self-shrinkage, dry shrinkage, plastic shrinkage, temperature expansion, frost heaving and so on inside different cement-based structures. This technique provides us a new useful measuring method on early curing monitoring of cement-based structures and greater understanding of details of their hardening process.

High resolution strain sensor for earthquake precursor observation and earthquake monitoring

NASA Astrophysics Data System (ADS)

Zhang, Wentao; Huang, Wenzhu; Li, Li; Liu, Wenyi; Li, Fang

2016-05-01

We propose a high-resolution static-strain sensor based on a FBG Fabry-Perot interferometer (FBG-FP) and a wavelet domain cross-correlation algorithm. This sensor is used for crust deformation measurement, which plays an important role in earthquake precursor observation. The Pound-Drever-Hall (PDH) technique based on a narrow-linewidth tunable fiber laser is used to interrogate the FBG-FPs. A demodulation algorithm based on wavelet domain cross-correlation is used to calculate the wavelength difference. The FBG-FP sensor head is fixed on the two steel alloy rods which are installed in the bedrock. The reference FBG-FP is placed in a strain-free state closely to compensate the environment temperature fluctuation. A static-strain resolution of 1.6 n(epsilon) can be achieved. As a result, clear solid tide signals and seismic signals can be recorded, which suggests that the proposed strain sensor can be applied to earthquake precursor observation and earthquake monitoring.

Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System.

PubMed

Ye, Xiao-Wei; Su, You-Hua; Xi, Pei-Sen

2018-02-07

In this paper, a fiber Bragg grating (FBG)-based stress monitoring system instrumented on an orthotropic steel deck arch bridge is demonstrated. The FBG sensors are installed at two types of critical fatigue-prone welded joints to measure the strain and temperature signals. A total of 64 FBG sensors are deployed around the rib-to-deck and rib-to-diagram areas at the mid-span and quarter-span of the investigated orthotropic steel bridge. The local stress behaviors caused by the highway loading and temperature effect during the construction and operation periods are presented with the aid of a wavelet multi-resolution analysis approach. In addition, the multi-modal characteristic of the rainflow counted stress spectrum is modeled by the method of finite mixture distribution together with a genetic algorithm (GA)-based parameter estimation approach. The optimal probability distribution of the stress spectrum is determined by use of Bayesian information criterion (BIC). Furthermore, the hot spot stress of the welded joint is calculated by an extrapolation method recommended in the specification of International Institute of Welding (IIW). The stochastic characteristic of stress concentration factor (SCF) of the concerned welded joint is addressed. The proposed FBG-based stress monitoring system and probabilistic stress evaluation methods can provide an effective tool for structural monitoring and condition assessment of orthotropic steel bridges.

Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System

PubMed Central

Ye, Xiao-Wei; Xi, Pei-Sen

2018-01-01

In this paper, a fiber Bragg grating (FBG)-based stress monitoring system instrumented on an orthotropic steel deck arch bridge is demonstrated. The FBG sensors are installed at two types of critical fatigue-prone welded joints to measure the strain and temperature signals. A total of 64 FBG sensors are deployed around the rib-to-deck and rib-to-diagram areas at the mid-span and quarter-span of the investigated orthotropic steel bridge. The local stress behaviors caused by the highway loading and temperature effect during the construction and operation periods are presented with the aid of a wavelet multi-resolution analysis approach. In addition, the multi-modal characteristic of the rainflow counted stress spectrum is modeled by the method of finite mixture distribution together with a genetic algorithm (GA)-based parameter estimation approach. The optimal probability distribution of the stress spectrum is determined by use of Bayesian information criterion (BIC). Furthermore, the hot spot stress of the welded joint is calculated by an extrapolation method recommended in the specification of International Institute of Welding (IIW). The stochastic characteristic of stress concentration factor (SCF) of the concerned welded joint is addressed. The proposed FBG-based stress monitoring system and probabilistic stress evaluation methods can provide an effective tool for structural monitoring and condition assessment of orthotropic steel bridges. PMID:29414850

Finite element modelling of fibre Bragg grating strain sensors and experimental validation

NASA Astrophysics Data System (ADS)

Malik, Shoaib A.; Mahendran, Ramani S.; Harris, Dee; Paget, Mark; Pandita, Surya D.; Machavaram, Venkata R.; Collins, David; Burns, Jonathan M.; Wang, Liwei; Fernando, Gerard F.

2009-03-01

Fibre Bragg grating (FBG) sensors continue to be used extensively for monitoring strain and temperature in and on engineering materials and structures. Previous researchers have also developed analytical models to predict the loadtransfer characteristics of FBG sensors as a function of applied strain. The general properties of the coating or adhesive that is used to surface-bond the FBG sensor to the substrate has also been modelled using finite element analysis. In this current paper, a technique was developed to surface-mount FBG sensors with a known volume and thickness of adhesive. The substrates used were aluminium dog-bone tensile test specimens. The FBG sensors were tensile tested in a series of ramp-hold sequences until failure. The reflected FBG spectra were recorded using a commercial instrument. Finite element analysis was performed to model the response of the surface-mounted FBG sensors. In the first instance, the effect of the mechanical properties of the adhesive and substrate were modelled. This was followed by modelling the volume of adhesive used to bond the FBG sensor to the substrate. Finally, the predicted values obtained via finite element modelling were correlated to the experimental results. In addition to the FBG sensors, the tensile test specimens were instrumented with surface-mounted electrical resistance strain gauges.

Relative adherence of Bacteroides species and strains to Actinomyces viscosus on saliva-coated hydroxyapatite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, J.; Ellen, R.P.

1989-09-01

The study was designed to compare the adherence of several Bacteroides species to A. viscosus. Using 3H, we labeled 24 laboratory strains, including 13 Bacteroides species and 11 fresh clinical isolates of three Bacteroides species. Their adherence to A. viscosus bound to a saliva-coated mineral surface was quantified by liquid scintillation. Adherence relative to a standard strain, B. gingivalis 2561, was compared. Among the lab bacteroides, those of B. gingivalis (eight strains) were the greatest binders (mean, 80.5 {plus minus} 12.4%). Strains of other lab bacteroides bound less well (mean, 33.4 {plus minus} 6.3%). The difference in means was statisticallymore » significant (p less than 0.01). The mean for B. gingivalis strains was also significantly greater than that for strains of B. intermedius (51.7 {plus minus} 6.2%). Attachment of B. gingivalis was saturable in experiments in which either input concentration or time was the independent variable, indicating that B. gingivalis cells do not accumulate in this vitro simulation of plaque formation by binding to each other. Subculture did not seem to affect the degree of binding.« less

Real-Time Characterization of Aerospace Structures Using Onboard Strain Measurement Technologies and Inverse Finite Element Method

DTIC Science & Technology

2011-09-01

strain data provided by in-situ strain sensors. The application focus is on the stain data obtained from FBG (Fiber Bragg Grating) sensor arrays...sparsely distributed lines to simulate strain data from FBG (Fiber Bragg Grating) arrays that provide either single-core (axial) or rosette (tri...when the measured strain data are sparse, as it is often the case when FBG sensors are used. For an inverse element without strain-sensor data, the

Serotype, hemolysin production, and adherence characteristics of strains of Escherichia coli causing urinary tract infection in dogs.

PubMed

Senior, D F; deMan, P; Svanborg, C

1992-04-01

Virulence factors were studied in 82 strains of Escherichia coli isolated from the urine of dogs with urinary tract infections. The most frequently expressed O antigens were 2, 4, 6, 25, and 22/83. Most strains were K nontypeable. Mannose-sensitive hemagglutination (MSH) with canine erythrocytes was observed in 71 strains and mannose-resistant hemagglutination (MRH) was observed in 32 strains. Strains that caused MSH of erythrocytes from dogs also caused MSH of erythrocytes from guinea pigs. Most strains that caused MRH of human A1P1 erythrocytes also reacted with erythrocytes of dogs. Of 22 strains (27%) that agglutinated human A1P1 erythrocytes, but not A1p erythrocytes, 17 (77%) had specificity for globo A, but did not react with the galactose alpha 1----4galactose beta disaccharide receptor. The remaining 5 strains and 2 others that simultaneously expressed an X adhesin agglutinated galactose alpha 1----4galactose beta-coated latex beads. Bacterial adherence to canine uroepithelial cells from the bladder was most often observed in strains expressing MSH, less often observed in strains expressing MRH, and least often observed in strains that failed to induce hemagglutination. Adherence of MSH strains to canine uroepithelial cells was inhibited by alpha-methyl-D-mannoside. As a group, MRH strains expressing globo-A- and galactose alpha 1----4galactose beta-specific adhesins did not have strong adherence. Strains of E coli isolated from dogs with urinary tract infections most commonly expressed type-1 fimbriae, and the main mechanism of in vitro adherence to canine uroepithelial cells involved a mannose-sensitive mechanism. Overrepresentation of globo-A-specific adhesins did not appear to be related to adherence of canine uroepithelial cells.

Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

PubMed

Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum

2014-06-10

In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

Vega interstage strain measurements: comparison between conventional strain gauges and fibre Bragg grating sensors

NASA Astrophysics Data System (ADS)

Cheng, Lun; Ahlers, Berit

2017-11-01

Europe is developing a new generation launcher, called Vega, a small launcher with a capacity to place satellites into polar and low-Earth orbits, which are used for many scientific and Earth observation missions. Its first launch is scheduled for early 2008. Dutch Space is responsible for the development, qualification and manufacturing of the Vega Interstage 1/2. This all-aluminium conically shaped section is designed as a monocoque structure. This subsystem of Vega has undergone its first qualification tests of force loading combined with an extensive programme of measurements (forces, displacements and strains), at TNO in Delft. In parallel to conventional strain gauges Fibre Optic Sensors (FOS) in the form of Fibre Bragg Grating (FBG) sensor arrays, consisting of five strain sensors and one temperature sensor, have been installed on different locations of the interstage. Direct comparisons of the results with conventional sensors during load tests up to several hundred tons are therefore possible. A self-evident benefit of FBG sensors in an array application is that each sensing FBG can have a different Bragg wavelength to reflect. Thus, Wavelength Division Multiplexing (WDM) can conveniently be used to distinguish the different sensing FBG's at the receiving side. First test results from load measurements performed on the Qualification Model (QM) of the Vega Interstage 1/2 are presented in this paper as well as an outlook to future integration of the FBG in this field.

Monitoring the corrosion process of reinforced concrete using BOTDA and FBG sensors.

PubMed

Mao, Jianghong; Chen, Jiayun; Cui, Lei; Jin, Weiliang; Xu, Chen; He, Yong

2015-04-15

Expansion and cracking induced by the corrosion of reinforcement concrete is the major factor in the failure of concrete durability. Therefore, monitoring of concrete cracking is critical for evaluating the safety of concrete structures. In this paper, we introduce a novel monitoring method combining Brillouin optical time domain analysis (BOTDA) and fiber Bragg grating (FBG), based on mechanical principles of concrete expansion cracking. BOTDA monitors concrete expansion and crack width, while FBG identifies the time and position of cracking. A water-pressure loading simulation test was carried out to determine the relationship between fiber strain, concrete expansion and crack width. An electrical accelerated corrosion test was also conducted to evaluate the ability of this novel sensor to monitor concrete cracking under practical conditions.

Monitoring the Corrosion Process of Reinforced Concrete Using BOTDA and FBG Sensors

PubMed Central

Mao, Jianghong; Chen, Jiayun; Cui, Lei; Jin, Weiliang; Xu, Chen; He, Yong

2015-01-01

Expansion and cracking induced by the corrosion of reinforcement concrete is the major factor in the failure of concrete durability. Therefore, monitoring of concrete cracking is critical for evaluating the safety of concrete structures. In this paper, we introduce a novel monitoring method combining Brillouin optical time domain analysis (BOTDA) and fiber Bragg grating (FBG), based on mechanical principles of concrete expansion cracking. BOTDA monitors concrete expansion and crack width, while FBG identifies the time and position of cracking. A water-pressure loading simulation test was carried out to determine the relationship between fiber strain, concrete expansion and crack width. An electrical accelerated corrosion test was also conducted to evaluate the ability of this novel sensor to monitor concrete cracking under practical conditions. PMID:25884790

In situ FBG inscription during fiber laser operation.

PubMed

Leich, Martin; Fiebrandt, Julia; Jetschke, Sylvia; Rothhardt, Manfred; Jäger, Matthias

2013-03-01

We demonstrate the inscription of a 266 nm UV femtosecond pulse-induced fiber Bragg grating (FBG) in an Yb-doped fiber during optical pumping at 976 nm and the initiation of lasing with increasing grating reflectivity. Output spectra show the emission of the pumped fiber changing from the broad-ranged amplified spontaneous emission in the nonlasing case to the narrow-range laser operation due to the enhancement of FBG reflectivity during inscription. The proposed technique enables the direct characterization and control of FBG performance in fiber lasers. After FBG fabrication, we investigate the spectral characteristics of the fiber laser for different laser powers and study the influence of a thermal treatment of the FBG.

Design and Experiment of FBG-Based Icing Monitoring on Overhead Transmission Lines with an Improvement Trial for Windy Weather

PubMed Central

Zhang, Min; Xing, Yimeng; Zhang, Zhiguo; Chen, Qiguan

2014-01-01

A scheme for monitoring icing on overhead transmission lines with fiber Bragg grating (FBG) strain sensors is designed and evaluated both theoretically and experimentally. The influences of temperature and wind are considered. The results of field experiments using simulated ice loading on windless days indicate that the scheme is capable of monitoring the icing thickness within 0–30 mm with an accuracy of ±1 mm, a load cell error of 0.0308v, a repeatability error of 0.3328v and a hysteresis error is 0.026%. To improve the measurement during windy weather, a correction factor is added to the effective gravity acceleration, and the absolute FBG strain is replaced by its statistical average. PMID:25615733

Design and experiment of FBG-based icing monitoring on overhead transmission lines with an improvement trial for windy weather.

PubMed

Zhang, Min; Xing, Yimeng; Zhang, Zhiguo; Chen, Qiguan

2014-12-12

A scheme for monitoring icing on overhead transmission lines with fiber Bragg grating (FBG) strain sensors is designed and evaluated both theoretically and experimentally. The influences of temperature and wind are considered. The results of field experiments using simulated ice loading on windless days indicate that the scheme is capable of monitoring the icing thickness within 0-30 mm with an accuracy of ±1 mm, a load cell error of 0.0308v, a repeatability error of 0.3328v and a hysteresis error is 0.026%. To improve the measurement during windy weather, a correction factor is added to the effective gravity acceleration, and the absolute FBG strain is replaced by its statistical average.

Fiber-MZI-based FBG sensor interrogation: comparative study with a CCD spectrometer.

PubMed

Das, Bhargab; Chandra, Vikash

2016-10-10

We present an experimental comparative study of the two most commonly used fiber Bragg grating (FBG) sensor interrogation techniques: a charge-coupled device (CCD) spectrometer and a fiber Mach-Zehnder interferometer (F-MZI). Although the interferometric interrogation technique is historically known to offer the highest sensitivity measurements, very little information exists regarding how it compares with the current commercially available spectral-characteristics-based interrogation systems. It is experimentally established here that the performance of a modern-day CCD spectrometer interrogator is very close to a F-MZI interrogator with the capability of measuring Bragg wavelength shifts with sub-picometer-level accuracy. The results presented in this research study can further be used as a guideline for choosing between the two FBG sensor interrogator types for small-amplitude dynamic perturbation measurements down to nano-level strain.

The Longitudinal Force Measurement of CWR Tracks with Hetero-Cladding FBG Sensors: A Proof of Concept.

PubMed

Shao, Li-Yang; Zhang, Meng; Xie, Kaize; Zhang, Xinpu; Wang, Ping; Yan, Lianshan

2016-12-18

A new method has been proposed to accurately determine longitudinal additional force in continuous welded rail (CWR) on bridges via hetero-cladding fiber Bragg grating (HC-FBG) sensors. The HC-FBG sensor consists of two FBGs written in the same type of fiber but with different cladding diameters. The HC-FBGs have the same temperature sensitivity but different strain sensitivity because of the different areas of the cross section. The differential strain coefficient is defined as the relative wavelength differences of two FBGs with the change of applied longitudinal force. In the verification experiment in the lab, the HC-FBGs were attached on a section of rail model of which the material property is the same as that of rail on line. The temperature and differential strain sensitivity were calibrated using a universal testing machine. As shown by the test results, the linearity between the relative wavelength difference and the longitudinal additional force is greater than 0.9999. The differential strain sensitivity is 4.85 × 10 -6 /N. Moreover, the relative wavelength difference is not affected by the temperature change. Compared to the theoretical results, the accumulated error is controlled within 5.0%.

Detection of the CS20 colonization factor antigen in diffuse-adhering E. coli strains

PubMed Central

Ochoa, Theresa J.; Rivera, Fulton P.; Bernal, Maria; Meza, Rina; Ecker, Lucie; Gil, Ana I.; Cepeda, David; Mosquito, Susan; Mercado, Erik; Maves, Ryan C.; Hall, Eric R.; Svennerholm, Ann-Mari; McVeigh, Annette; Savarino, Stephen; Lanata, Claudio F.

2011-01-01

We analyzed a randomly-selected group of 30 diffusely adherent (DAEC), 30 enteropathogenic, 30 enteroaggregative, and 5 shiga toxin-producing E. coli strains isolated from children with diarrhea. Enterotoxigenic E. coli (ETEC) colonization factors (CFs) were evaluated by dot-blot assay using 21 CF-specific monoclonal antibodies. Out of 95 non-ETEC strains, three DAEC were found to express CS20. No other E. coli expressed CFs. We confirmed the 3 CS20-positive strains as ETEC-negative by repeat PCR and as toxin-negative by GM1-ELISA. To our knowledge, this is the first study that has identified currently-recognized CFs in non-ETEC diarrheagenic E. coli strains identified by molecular methods. CFs may be an unrecognized relevant adherence factor in other E. coli, which may then play a role in pathogenesis and the immune response of the host. PMID:21064230

[Monitoring of Crack Propagation in Repaired Structures Based on Characteristics of FBG Sensors Reflecting Spectra].

PubMed

Yuan, Shen-fang; Jin, Xin; Qiu, Lei; Huang, Hong-mei

2015-03-01

In order to improve the security of aircraft repaired structures, a method of crack propagation monitoring in repaired structures is put forward basing on characteristics of Fiber Bragg Grating (FBG) reflecting spectra in this article. With the cyclic loading effecting on repaired structure, cracks propagate, while non-uniform strain field appears nearby the tip of crack which leads to the FBG sensors' reflecting spectra deformations. The crack propagating can be monitored by extracting the characteristics of FBG sensors' reflecting spectral deformations. A finite element model (FEM) of the specimen is established. Meanwhile, the distributions of strains which are under the action of cracks of different angles and lengths are obtained. The characteristics, such as main peak wavelength shift, area of reflecting spectra, second and third peak value and so on, are extracted from the FBGs' reflecting spectral which are calculated by transfer matrix algorithm. An artificial neural network is built to act as the model between the characteristics of the reflecting spectral and the propagation of crack. As a result, the crack propagation of repaired structures is monitored accurately and the error of crack length is less than 0.5 mm, the error of crack angle is less than 5 degree. The accurately monitoring problem of crack propagation of repaired structures is solved by taking use of this method. It has important significance in aircrafts safety improvement and maintenance cost reducing.

Isolation of Thermal and Strain Responses in Composites Using Embedded Fiber Bragg Grating Temperature Sensors

DTIC Science & Technology

2013-05-10

13. SUPPLEMENTARY NOTES 14. ABSTRACT In this research, fiber Bragg grating ( FBG ) optical temperature sensors are used for structural health...surface of a composite structure. FBG sensors also respond to axial strain in the optical fiber, thus any structural strain experienced by the composite...features. First, a three-dimensional array of FBG temperature sensors has been embedded in a carbon/epoxy composite structure, consisting of both in

Strain Modal Analysis of Small and Light Pipes Using Distributed Fibre Bragg Grating Sensors

PubMed Central

Huang, Jun; Zhou, Zude; Zhang, Lin; Chen, Juntao; Ji, Chunqian; Pham, Duc Truong

2016-01-01

Vibration fatigue failure is a critical problem of hydraulic pipes under severe working conditions. Strain modal testing of small and light pipes is a good option for dynamic characteristic evaluation, structural health monitoring and damage identification. Unique features such as small size, light weight, and high multiplexing capability enable Fibre Bragg Grating (FBG) sensors to measure structural dynamic responses where sensor size and placement are critical. In this paper, experimental strain modal analysis of pipes using distributed FBG sensors ispresented. Strain modal analysis and parameter identification methods are introduced. Experimental strain modal testing and finite element analysis for a cantilever pipe have been carried out. The analysis results indicate that the natural frequencies and strain mode shapes of the tested pipe acquired by FBG sensors are in good agreement with the results obtained by a reference accelerometer and simulation outputs. The strain modal parameters of a hydraulic pipe were obtained by the proposed strain modal testing method. FBG sensors have been shown to be useful in the experimental strain modal analysis of small and light pipes in mechanical, aeronautic and aerospace applications. PMID:27681728

Coherent pulse interrogation system for fiber Bragg grating sensing of strain and pressure in dynamic extremes of materials.

PubMed

Rodriguez, George; Jaime, Marcelo; Balakirev, Fedor; Mielke, Chuck H; Azad, Abul; Marshall, Bruce; La Lone, Brandon M; Henson, Bryan; Smilowitz, Laura

2015-06-01

A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain and pressure sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber is used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor are detected as a pulsed time domain waveform shift after encoding by the chromatic dispersive line. Signals are recorded using a single 35 GHz photodetector and a 50 G Samples per second, 25 GHz bandwidth, digitizing oscilloscope. Application of this approach to high-speed strain sensing in magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts are used to study magnetic field driven magnetostriction effects in LaCoO₃. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10^-4) in the material. A second application used FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. Both applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.

Coherent pulse interrogation system for fiber Bragg grating sensing of strain and pressure in dynamic extremes of materials

DOE PAGES

Rodriguez, George; Jaime, Marcelo; Balakirev, Fedor; ...

2015-05-21

A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain and pressure sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber is used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor are detected as a pulsed time domain waveform shift after encoding by the chromatic dispersivemore » line. Signals are recorded using a single 35 GHz photodetector and a 50 GSamples per second, 25 GHz bandwidth, digitizing oscilloscope. Application of this approach to high-speed strain sensing in magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts are used to study magnetic field driven magnetostriction effects in LaCoO₃. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10⁻⁴) in the material. A second application used FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. In conclusion, both applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.« less

Research on FBG-based longitudinal-acousto-optic modulator with Fourier mode coupling method.

PubMed

Li, Zhuoxuan; Pei, Li; Liu, Chao; Ning, Tigang; Yu, Shaowei

2012-10-20

Fourier mode coupling model was first applied to achieve the spectra property of a fiber Bragg grating (FBG)-based longitudinal-acousto-optic modulator. Compared with traditional analysis algorithms, such as the transfer matrix method, the Fourier mode coupling model could improve the computing efficiency up to 100 times with a guarantee of accuracy. In this paper, based on the theoretical analysis of this model, the spectra characteristics of the modulator in different frequencies and acoustically induced strains were numerically simulated. In the experiment, a uniform FBG was modulated by acoustic wave (AW) at 12 different frequencies. In particular, the modulator responses at 563 and 885.5 KHz with three different lead zirconate titanate (PZT) loads applied were plotted for illustration, and the linear fitting of experimental data demonstrated a good match with the simulation result. The acoustic excitation of the longitudinal wave is obtained using a conic silica horn attached to the surface of a shear-mode PZT plate paralleled to the fiber axis. This way of generating longitudinal AW with a transversal PZT may shed light on the optimal structural design for the FBG-based longitudinal-acousto-optic modulator.

Application of Multiplexed FBG and PZT Impedance Sensors for Health Monitoring of Rocks.

PubMed

Yang, Yaowen; Annamdas, Venu Gopal Madhav; Wang, Chao; Zhou, Yingxin

2008-01-21

Reliable structural health monitoring (SHM) including nondestructiveevaluation (NDE) is essential for safe operation of infrastructure systems. Effectivemonitoring of the rock components of civil infrastructures such as tunnels and cavernsremains challenging. The feasibility of employing smart optical fibre sensor (OFS) andpiezoelectric impedance sensor made up of lead zirconate titanate (PZT) forcomprehensive health monitoring of rocks, covering load history monitoring/retrieval aswell as damage assessment is presented in this paper. The rock specimens are subjected tocyclic loading and their conditions are continuously monitored using OFS and PZTsensors. OFS based multiplexed fibre Bragg grating (FBG) sensors are surface bonded onthe rock specimens. Their strain sensing performance is compared with the conventionalelectric strain gauges (ESGs). In addition, PZT patches are also bonded on the specimensto study the damage pattern during different loading cycles. Unlike the FBGs or ESGs,PZT patches are used as bi-functional sensors and actuators, enabling them to be efficientdetectors of incipient damages using the principle of electromechanical impedance. Theexperimental study demonstrated superior performance of these smart FBG and PZTimpedance sensors. This work is expected to be useful for SHM based NDE application ofrock structures such as caverns and tunnels.

Strain-specific inhibition of the adherence of uropathogenic bacteria to bladder cells by probiotic Lactobacillus spp.

PubMed

de Llano, Dolores González; Arroyo, Amalia; Cárdenas, Nivia; Rodríguez, Juan Miguel; Moreno-Arribas, M Victoria; Bartolomé, Begoña

2017-06-01

Urinary tract infections (UTIs), one of most common infections worldwide, face high recurrence rates and increasing antimicrobial resistance. Probiotic bacteria, especially of the genus Lactobacillus, are considered a promising preventive and/or treatment therapy against UTIs. In order to elucidate the mechanisms involved in these beneficial effects, we studied the impact of different Lactobacillus strains (Lactobacillus salivarius UCM572, L. plantarum CLC17 and L. acidophilus 01) in the adherence of reference and clinical uropathogenic strains (Escherichia coli ATCC® 53503, E. coli 10791, Enterococcus faecalis 04-1, En. faecalis 08-1 and Staphylococcus epidermidis 08-3) to T24 epithelial bladder cells. In general, the Lactobacillus strains with previous in vivo evidence of beneficial effects against UTIs (L. salivarius UCM572 and L. acidophilus 01) significantly inhibited the adherence of the five uropathogens to T24 cells, displaying percentages of inhibition ranging between 22.2% and 43.9%, and between 16.5% and 53.7%, respectively. On the other hand, L. plantarum CLC17, a strain with no expected effects on UTIs, showed almost negligible anti-adherence effects.Therefore, these in vitro results suggest that inhibition of the adherence of uropathogens to epithelial bladder cells may be one of the mechanisms involved in the potential beneficial effects of probiotics against UTIs in vivo. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Structural Stability Monitoring of a Physical Model Test on an Underground Cavern Group during Deep Excavations Using FBG Sensors.

PubMed

Li, Yong; Wang, Hanpeng; Zhu, Weishen; Li, Shucai; Liu, Jian

2015-08-31

Fiber Bragg Grating (FBG) sensors are comprehensively recognized as a structural stability monitoring device for all kinds of geo-materials by either embedding into or bonding onto the structural entities. The physical model in geotechnical engineering, which could accurately simulate the construction processes and the effects on the stability of underground caverns on the basis of satisfying the similarity principles, is an actual physical entity. Using a physical model test of underground caverns in Shuangjiangkou Hydropower Station, FBG sensors were used to determine how to model the small displacements of some key monitoring points in the large-scale physical model during excavation. In the process of building the test specimen, it is most successful to embed FBG sensors in the physical model through making an opening and adding some quick-set silicon. The experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like electrical resistance strain gages and extensometers. The experimental results are also in good agreement with the numerical simulation results. In conclusion, FBG sensors could effectively measure small displacements of monitoring points in the whole process of the physical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in situ engineering construction.

Structural Stability Monitoring of a Physical Model Test on an Underground Cavern Group during Deep Excavations Using FBG Sensors

PubMed Central

Li, Yong; Wang, Hanpeng; Zhu, Weishen; Li, Shucai; Liu, Jian

2015-01-01

Fiber Bragg Grating (FBG) sensors are comprehensively recognized as a structural stability monitoring device for all kinds of geo-materials by either embedding into or bonding onto the structural entities. The physical model in geotechnical engineering, which could accurately simulate the construction processes and the effects on the stability of underground caverns on the basis of satisfying the similarity principles, is an actual physical entity. Using a physical model test of underground caverns in Shuangjiangkou Hydropower Station, FBG sensors were used to determine how to model the small displacements of some key monitoring points in the large-scale physical model during excavation. In the process of building the test specimen, it is most successful to embed FBG sensors in the physical model through making an opening and adding some quick-set silicon. The experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like electrical resistance strain gages and extensometers. The experimental results are also in good agreement with the numerical simulation results. In conclusion, FBG sensors could effectively measure small displacements of monitoring points in the whole process of the physical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in situ engineering construction. PMID:26404287

The influence of adhesive on fiber Bragg grating strain sensor

NASA Astrophysics Data System (ADS)

Chen, Jixuan; Gong, Huaping; Jin, Shangzhong; Li, Shuhua

2009-08-01

A fiber Bragg grating (FBG) sensor was fixed on the uniform strength beam with three adhesives, which were modified acrylate, glass glue and epoxy resin. The influence of adhesive on FBG strain sensor was investigated. The strain of FBG sensor was varied by loading weight to the uniform strength beam. The wavelength shift of the FBG sensor fixed by the three kinds of adhesive were measured with different weight at the temperatures 0°C, 10°C, 20°C, 30°C, 40°C. The linearity, sensitivity and their stability at different temperature of FBG sensor which fixed by every kind of adhesives were analyzed. The results show that, the FBG sensor fixed by the modified acrylate has a high linearity, and the linear correlation coefficient is 0.9996. It also has a high sensitivity which is 0.251nm/kg. The linearity and the sensitivity of the FBG sensor have a high stability at different temperatures. The FBG sensor fixed by the glass glue also has a high linearity, and the linear correlation coefficient is 0.9986, but it has a low sensitivity which is only 0.041nm/kg. The linearity and the sensitivity of the FBG sensor fixed by the glass glue have a high stability at different temperatures. When the FBG sensor is fixed by epoxy resin, the sensitivity and linearity is affected significantly by the temperature. When the temperature changes from 0°C to 40°C, the sensitivity decreases from 0.302nm/kg to 0.058nm/kg, and the linear correlation coefficient decreases from 0.9999 to 0.9961.

Comparative assessment of erbium fiber ring lasers and reflective SOA linear lasers for fiber Bragg grating dynamic strain sensing.

PubMed

Wei, Heming; Krishnaswamy, Sridhar

2017-05-01

Fiber Bragg grating (FBG) dynamic strain sensors using both an erbium-based fiber ring laser configuration and a reflective semiconductor optical amplifier (RSOA)-based linear laser configuration are investigated theoretically and experimentally. Fiber laser models are first presented to analyze the output characteristics of both fiber laser configurations when the FBG sensor is subjected to dynamic strains at high frequencies. Due to differences in the transition times of erbium and the semiconductor (InP/InGaAsP), erbium-doped fiber amplifier (EDFA)- and RSOA-based fiber lasers exhibit different responses and regimes of stability when the FBG is subjected to dynamic strains. The responses of both systems are experimentally verified using an adaptive photorefractive two-wave mixing (TWM) spectral demodulation technique. The experimental results show that the RSOA-FBG fiber linear cavity laser is stable and can stably respond to dynamic strains at high frequencies. An example application using a multiplexed TWM interferometer to demodulate multiple FBG sensors is also discussed.

On-line structural health and fire monitoring of a composite personal aircraft using an FBG sensing system

NASA Astrophysics Data System (ADS)

Chandler, K.; Ferguson, S.; Graver, T.; Csipkes, A.; Mendez, A.

2008-03-01

We report in this paper on the design and development of a novel on-line structural health monitoring and fire detection system based on an array of optical fiber Bragg grating (FBG) sensors and interrogation system installed on a new, precommercial compact aircraft. A combined total of 17 FBG sensors - strain, temperature and high-temperature - were installed at critical locations in an around the wings, fuselage and engine compartment of a prototype, Comp Air CA 12 all-composite, ten-passenger personal airplane powered by a 1,650 hp turbine engine. The sensors are interrogated online and in real time by a swept laser FBG interrogator (Micron Optics sm125-700) mounted on board the plane. Sensors readings are then combined with the plane's avionics system and displayed on the pilot's aviation control panel. This system represents the first of its kind in commercial, small frame, airplanes and a first for optical fiber sensors.

A Laboratory Experimental Study: An FBG-PVC Tube Integrated Device for Monitoring the Slip Surface of Landslides

PubMed Central

Zhang, Shaojie; Chen, Jiang; Teng, Pengxiao; Wei, Fangqiang; Chen, Qiao

2017-01-01

A new detection device was designed by integrating fiber Bragg grating (FBG) and polyvinyl chloride (PVC) tube in order to monitor the slip surface of a landslide. Using this new FBG-based device, a corresponding slope model with a pre-set slip surface was designed, and seven tests with different soil properties were carried out in laboratory conditions. The FBG sensing fibers were fixed on the PVC tube to measure strain distributions of PVC tube at different elevation. Test results indicated that the PVC tube could keep deformation compatible with soil mass. The new device was able to monitor slip surface location before sliding occurrence, and the location of monitored slip surface was about 1–2 cm above the pre-set slip surface, which basically agreed with presupposition results. The monitoring results are expected to be used to pre-estimate landslide volume and provide a beneficial option for evaluating the potential impact of landslides on shipping safety in the Three Gorges area. PMID:29084157

A Laboratory Experimental Study: An FBG-PVC Tube Integrated Device for Monitoring the Slip Surface of Landslides.

PubMed

Wang, Kai; Zhang, Shaojie; Chen, Jiang; Teng, Pengxiao; Wei, Fangqiang; Chen, Qiao

2017-10-30

A new detection device was designed by integrating fiber Bragg grating (FBG) and polyvinyl chloride (PVC) tube in order to monitor the slip surface of a landslide. Using this new FBG-based device, a corresponding slope model with a pre-set slip surface was designed, and seven tests with different soil properties were carried out in laboratory conditions. The FBG sensing fibers were fixed on the PVC tube to measure strain distributions of PVC tube at different elevation. Test results indicated that the PVC tube could keep deformation compatible with soil mass. The new device was able to monitor slip surface location before sliding occurrence, and the location of monitored slip surface was about 1-2 cm above the pre-set slip surface, which basically agreed with presupposition results. The monitoring results are expected to be used to pre-estimate landslide volume and provide a beneficial option for evaluating the potential impact of landslides on shipping safety in the Three Gorges area.

A temperature compensated fibre Bragg grating (FBG)-based sensor system for condition monitoring of electrified railway pantograph

NASA Astrophysics Data System (ADS)

Chen, Ye; Vidakovic, Miodrag; Fabian, Matthias; Swift, Martin; Brun, Lee; Sun, Tong; Grattan, Kenneth T. V.

2017-04-01

This paper presents the results obtained from fibre Bragg grating (FBG) sensors integrated into a railway current-collecting pantograph for accurate measurement of contact force and contact location when it is subjected to various temperature conditions. The temperature change of the pantograph is simulated, at the industrial laboratory of Brecknell Willis in the UK, by changing the DC current applied to pantograph from 0 to 1500 A. This test is primarily designed to verify the effectiveness of the temperature compensation mechanism built in the FBG sensor design. For this verification, 3 thermocouples co-located with the FBG sensor packages are used to measure the temperature change seen from 25 °C to 55 °C. The tests were repeated several times and the sensor system has shown its temperatureindependence, confirming that the intrinsic cross-sensitivity of FBGs to temperature variation for strain measurement has been fully compensated through the use of this innovative sensor design and data processing.

Monitoring the Damage State of Fiber Reinforced Composites Using an FBG Network for Failure Prediction.

PubMed

Kocaman, Esat Selim; Akay, Erdem; Yilmaz, Cagatay; Turkmen, Halit Suleyman; Misirlioglu, Ibrahim Burc; Suleman, Afzal; Yildiz, Mehmet

2017-01-03

A structural health monitoring (SHM) study of biaxial glass fibre-reinforced epoxy matrix composites under a constant, high strain uniaxial fatigue loading is performed using fibre Bragg grating (FBG) optical sensors embedded in composites at various locations to monitor the evolution of local strains, thereby understanding the damage mechanisms. Concurrently, the temperature changes of the samples during the fatigue test have also been monitored at the same locations. Close to fracture, significant variations in local temperatures and strains are observed, and it is shown that the variations in temperature and strain can be used to predict imminent fracture. It is noted that the latter information cannot be obtained using external strain gages, which underlines the importance of the tracking of local strains internally.

Monitoring the Damage State of Fiber Reinforced Composites Using an FBG Network for Failure Prediction

PubMed Central

Kocaman, Esat Selim; Akay, Erdem; Yilmaz, Cagatay; Turkmen, Halit Suleyman; Misirlioglu, Ibrahim Burc; Suleman, Afzal; Yildiz, Mehmet

2017-01-01

A structural health monitoring (SHM) study of biaxial glass fibre-reinforced epoxy matrix composites under a constant, high strain uniaxial fatigue loading is performed using fibre Bragg grating (FBG) optical sensors embedded in composites at various locations to monitor the evolution of local strains, thereby understanding the damage mechanisms. Concurrently, the temperature changes of the samples during the fatigue test have also been monitored at the same locations. Close to fracture, significant variations in local temperatures and strains are observed, and it is shown that the variations in temperature and strain can be used to predict imminent fracture. It is noted that the latter information cannot be obtained using external strain gages, which underlines the importance of the tracking of local strains internally. PMID:28772393

Long-term monitoring FBG-based cable load sensor

NASA Astrophysics Data System (ADS)

Zhang, Zhichun; Zhou, Zhi; Wang, Chuan; Ou, Jinping

2006-03-01

Stay cables are the main load-bearing components of stayed-cable bridges. The cables stress status is an important factor to the stayed-cable bridge structure safety evaluation. So it's very important not only to the bridge construction, but also to the long-term safety evaluation for the bridge structure in-service. The accurate measurement for cable load depends on an effective sensor, especially to meet the long time durability and measurement demand. FBG, for its great advantage of corrosion resistance, absolute measurement, high accuracy, electro-magnetic resistance, quasi-distribution sensing, absolute measurement and so on, is the most promising sensor, which can cater for the cable force monitoring. In this paper, a load sensor has been developed, which is made up of a bushing elastic supporting body, 4 FBGs uniformly-spaced attached outside of the bushing supporting body, and a temperature compensation FBG for other four FBGs, moreover a cover for protection of FBGs. Firstly, the sensor measuring principle is analyzed, and relationship equation of FBG wavelength shifts and extrinsic load has also been gotten. And then the sensor calibration experiments of a steel cable stretching test with the FBG load sensor and a reference electric pressure sensor is finished, and the results shows excellent linearity of extrinsic load and FBG wavelength shifts, and good repeatability, which indicates that such kind of FBG-based load sensor is suitable for load measurement, especially for long-term, real time monitoring of stay-cables.

Development of an FBG-based low temperature measurement system for cargo containment of LNG tankers

NASA Astrophysics Data System (ADS)

Kim, D. G.; Yoo, W.; Swinehart, P.; Jiang, B.; Haber, T.; Mendez, A.

2007-09-01

Given the growing demand for oil and natural gas to meet the world's energy needs, there is nowadays renewed interest in the use of liquefied natural gas (LNG) systems. For LNG to remain in its liquid phase, the gas has to be kept at cryogenic temperatures (< 160°C). And, as part of the LNG supply process, it becomes necessary to transport it using massive carrier tankers with cargo hulls operating at low temperatures and using special insulating double-wall construction. The safe and reliable storage and transportation of LNG products calls for low temperature monitoring of said containers to detect the onset of any potential leaks and possible thermal insulation degradation. Because of the hazardous nature of this cargo, only intrinsically-safe, explosion proof devices can be used. Optical fiber sensors-- such as fiber Bragg gratings-- are ideal for this application given their dielectric nature and multi-point sensing telemetry capability. In this paper, we describe the development of an on-line, multi-point FBG-based low temperature monitoring system based on a network of specially packaged FBG temperature and strain sensors mounted at critical locations within the inner hull, cofferdam and secondary barriers of a LNG carrier tanker. Given the stringent cryogenic operating temperature conditions, pertinent FBG designs, coatings and packaging approaches were formulated along with adequate installation techniques and integration of the interrogating FBG electronics into the tanker's overall SCADA monitoring system. FBG temperature sensors were demonstrated to be stable and sensitive over the 80-480K range. Stability is +/- 0.25K or better with repeated calibrations, and long term stability at 480K is ~0.2mK/hour.

Long-gauge FBGs interrogated by DTR3 for dynamic distributed strain measurement of helicopter blade model

NASA Astrophysics Data System (ADS)

Nishiyama, M.; Igawa, H.; Kasai, T.; Watanabe, N.

2014-05-01

In this paper, we describe characteristics of distributed strain sensing based on a Delayed Transmission/Reflection Ratiometric Reflectometry (DTR3) scheme with a long-gauge Fiber Bragg Grating (FBG), which is attractive to dynamic structural deformation monitoring such as a helicopter blade and an airplane wing. The DTR3 interrogator using the longgauge FBG has capability of detecting distributed strain with 50 cm spatial resolution in 100 Hz sampling rate. We evaluated distributed strain sensing characteristics of the long-gauge FBG attached on a 5.5 m helicopter blade model in static tests and free vibration dynamic tests.

Theoretical analysis and coating thickness determination of a dual layer metal coated FBG sensor for sensitivity enhancement at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Ramalingam, Rajinikumar; Atrey, M. D.

2017-12-01

Use of Fiber Bragg Grating (FBG) sensor is very appealing for sensing low temperature and strain in superconducting magnets because of their miniature size and the possibility of accommodating many sensors in a single fiber. The main drawback is their low intrinsic thermal sensitivity at low temperatures below 120 K. Approaching cryogenic temperatures, temperature changes lower than a few degrees Kelvin cannot be resolved, since they do not cause an appreciable shift of the wavelength diffracted by a bare FBG sensor. To improve the thermal sensitivity and thermal inertia below 77 K, the Bare FBG (BFBG) sensor can be coated with high thermal expansion coefficient materials. In this work, different metal were considered for coating the FBG sensor. For theoretical investigation, a double layered circular thick wall tube model has been considered to study the effect on sensitivity due to the mechanical properties like Young’s modulus, Thermal expansion coefficient, Poisson’s ratio of selected materials at a various cryogenic temperatures. The primary and the secondary coating thickness for a dual layer metal coated FBG sensor have been determined from the above study. The sensor was then fabricated and tested at cryogenic temperature range from 4-300 K. The cryogenic temperature characteristics of the tested sensors are reported.

Applications of FBG sensors on telecom satellites

NASA Astrophysics Data System (ADS)

Abad, S.; Araújo, F. M.; Ferreira, L. A.; Pedersen, F.; Esteban, M. A.; McKenzie, I.; Karafolas, N.

2017-11-01

Monitoring needs of spacecraft are rapidly increasing due to new and more challenging missions, along with demands to reduce launching costs by minimizing the manufacture, assembly, integration and test time and employing new low weight materials balanced by the need for maximizing system lifetime while maintaining good reliability. Conventional electronic sensors are characterized by their low multiplexing capability and their EMI/RF susceptibility and it is in this scenario that Fiber Optic Sensors (FOS) in general, and more specifically Fiber Bragg Grating (FBG) technology offers important benefits, improving in various ways the already deployed sensing subsystems (e.g. reducing the weight associated with sensor cabling, increasing the number of sensing points) and enabling new monitoring applications that were not possible by using conventional sensing technologies. This work presents the activities performed and the lessons learnt in the frame of ESA's ARTES-5 project "Fiber Optic Sensing Subsystem for Spacecraft Health Monitoring in Telecommunication Satellites". This project finished in July 2009, with the implementation and testing of two different demonstrators employing FBG sensor technology: FBG sensors for temperature monitoring in high voltage environments, and in particular in several parts of electric propulsion subsystems [1], and FBG sensors for thermal monitoring of array-antennas during RF testing [2]. In addition, the contacts performed with different actors within the space community allowed the identification of a special area of interest for the substitution of regular thermocouple instrumentation by FBG technology for thermal vacuum ground testing of satellites.

Optimization design of the tuning method for FBG spectroscopy based on the numerical analysis of all-fiber Raman temperature lidar

NASA Astrophysics Data System (ADS)

Wang, Li; Wang, Jun; Bao, Dong; Yang, Rong; Yan, Qing; Gao, Fei; Hua, Dengxin

2018-01-01

All fiber Raman temperature lidar for space borne platform has been proposed for profiling of the temperature with high accuracy. Fiber Bragg grating (FBG) is proposed as the spectroscopic system of Raman lidar because of good wavelength selectivity, high spectral resolution and high out-of-band rejection rate. Two sets of FBGs at visible wavelength 532 nm as Raman spectroscopy system are designed for extracting the rotational Raman spectra of atmospheric molecules, which intensities depend on the atmospheric temperature. The optimization design of the tuning method of an all-fiber rotational Raman spectroscopy system is analyzed and tested for estimating the potential temperature inversion error caused by the instability of FBG. The cantilever structure with temperature control device is designed to realize the tuning and stabilization of the central wavelengths of FBGs. According to numerical calculation of FBG and finite element analysis of the cantilever structure, the center wavelength offset of FBG is 11.03 nm/°C with the temperature change in the spectroscopy system. By experimental observation, the center wavelength offset of surface-bonded FBG is 9.80 nm/°C with temperature changing when subjected to certain strain for the high quantum number channel, while 10.01 nm/°C for the low quantum number channel. The tunable wavelength range of FBG is from 528.707 nm to 529.014 nm for the high quantum number channel and from 530.226 nm to 530.547 nm for the low quantum number channel. The temperature control accuracy of the FBG spectroscopy system is up to 0.03 °C, the corresponding potential atmospheric temperature inversion error is 0.04 K based on the numerical analysis of all-fiber Raman temperature lidar. The fine tuning and stabilization of the FBG wavelength realize the elaborate spectroscope of Raman lidar system. The conclusion is of great significance for the application of FBG spectroscopy system for space-borne platform Raman lidar.

A spectral profile multiplexed FBG sensor network with application to strain measurement in a Kevlar woven fabric

NASA Astrophysics Data System (ADS)

Guo, Guodong; Hackney, Drew; Pankow, Mark; Peters, Kara

2017-04-01

A spectral profile division multiplexed fiber Bragg grating (FBG) sensor network is described in this paper. The unique spectral profile of each sensor in the network is identified as a distinct feature to be interrogated. Spectrum overlap is allowed under working conditions. Thus, a specific wavelength window does not need to be allocated to each sensor as in a wavelength division multiplexed (WDM) network. When the sensors are serially connected in the network, the spectrum output is expressed through a truncated series. To track the wavelength shift of each sensor, the identification problem is transformed to a nonlinear optimization problem, which is then solved by a modified dynamic multi-swarm particle swarm optimizer (DMS-PSO). To demonstrate the application of the developed network, a network consisting of four FBGs was integrated into a Kevlar woven fabric, which was under a quasi-static load imposed by an impactor head. Due to the substantial radial strain in the fabric, the spectrums of different FBGs were found to overlap during the loading process. With the developed interrogating method, the overlapped spectrum would be distinguished thus the wavelength shift of each sensor can be monitored.

Application of Multiplexed FBG and PZT Impedance Sensors for Health Monitoring of Rocks

PubMed Central

Yang, Yaowen; Annamdas, Venu Gopal Madhav; Wang, Chao; Zhou, Yingxin

2008-01-01

Reliable structural health monitoring (SHM) including nondestructive evaluation (NDE) is essential for safe operation of infrastructure systems. Effective monitoring of the rock components of civil infrastructures such as tunnels and caverns remains challenging. The feasibility of employing smart optical fibre sensor (OFS) and piezoelectric impedance sensor made up of lead zirconate titanate (PZT) for comprehensive health monitoring of rocks, covering load history monitoring/retrieval as well as damage assessment is presented in this paper. The rock specimens are subjected to cyclic loading and their conditions are continuously monitored using OFS and PZT sensors. OFS based multiplexed fibre Bragg grating (FBG) sensors are surface bonded on the rock specimens. Their strain sensing performance is compared with the conventional electric strain gauges (ESGs). In addition, PZT patches are also bonded on the specimens to study the damage pattern during different loading cycles. Unlike the FBGs or ESGs, PZT patches are used as bi-functional sensors and actuators, enabling them to be efficient detectors of incipient damages using the principle of electromechanical impedance. The experimental study demonstrated superior performance of these smart FBG and PZT impedance sensors. This work is expected to be useful for SHM based NDE application of rock structures such as caverns and tunnels. PMID:27879708

In vitro probiotic characterization of Lactobacillus strains from fermented radish and their anti-adherence activity against enteric pathogens.

PubMed

Damodharan, Karthiyaini; Palaniyandi, Sasikumar Arunachalam; Yang, Seung Hwan; Suh, Joo-Won

2015-11-01

In this study, we evaluated the probiotic properties of Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus fermentum strains isolated from fermented radish. All the strains survived the simulated oro-gastrointestinal transit condition and showed significantly higher adherence to Caco-2 cells compared with the probiotic strain Lactobacillus rhamnosus GG. The strains showed broad-spectrum antimicrobial activity, autoaggregation, and coaggregation capacity with pathogens. Furthermore, the Lactobacillus strains inhibited the adherence of Yersinia enterocolitica subsp. enterocolitica, Shigella boydii, and Salmonella choleraesuis to the Caco-2 cell line. The strains possessed bile salt hydrolase activity and their cholesterol-lowering activity in vitro was above 50% in the presence of bile. Strains of L. plantarum and L. pentosus possessed the plantaricin-encoding plnEF gene. In addition, the Lactobacillus strains maintained about 80% cell viability after freeze-drying in the presence of a combination of 5% skim milk and 5% maltodextrin as cryoprotectant, and 70% recovery of cell viability was observed in the absence of any cryoprotectant.

Microplate Fluorescence Assay for Measurement of the Ability of Strains of Listeria monocytogenes from Meat and Meat-Processing Plants To Adhere to Abiotic Surfaces▿

PubMed Central

Gamble, Rachel; Muriana, Peter M.

2007-01-01

Listeria monocytogenes is a significant food-borne pathogen that is capable of adhering to and producing biofilms on processing equipment, making it difficult to eliminate from meat-processing environments and allowing potential contamination of ready-to-eat (RTE) products. We devised a fluorescence-based microplate method for screening isolates of L. monocytogenes for the ability to adhere to abiotic surfaces. Strains of L. monocytogenes were incubated for 2 days at 30°C in 96-well microplates, and the plates were washed in a plate washer. The retained cells were incubated for 15 min at 25°C with 5,6-carboxyfluorescein diacetate and washed again, and then the fluorescence was read with a plate reader. Several enzymatic treatments (protease, lipase, and cellulase) were effective in releasing adherent cells from the microplates, and this process was used for quantitation on microbiological media. Strongly adherent strains of L. monocytogenes were identified that had 15,000-fold-higher levels of fluorescence and 100,000-fold-higher plate counts in attachment assays than weakly adherent strains. Strongly adherent strains of L. monocytogenes adhered equally well to four different substrates (glass, plastic, rubber, and stainless steel); showed high-level attachment on microplates at 10, 20, 30, and 40°C; and showed significant differences from weakly adherent strains when examined by scanning electron microscopy. A greater incidence of strong adherence was observed for strains isolated from RTE meats than for those isolated from environmental surfaces. Analysis of surface adherence among Listeria isolates from processing environments may provide a better understanding of the molecular mechanisms involved in attachment and suggest solutions to eliminate them from food-processing environments. PMID:17586676

Temperature-compensated strain measurement using fiber Bragg grating sensors embedded in composite laminates

NASA Astrophysics Data System (ADS)

Tanaka, Nobuhira; Okabe, Yoji; Takeda, Nobuo

2003-12-01

For accurate strain measurement by fiber Bragg grating (FBG) sensors, it is necessary to compensate the influence of temperature change. In this study two devices using FBG sensors have been developed for temperature-compensated strain measurement. They are named 'hybrid sensor' and 'laminate sensor', respectively. The former consists of two different materials connected in series: carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic. Each material contains an FBG sensor with a different Bragg wavelength, and both ends of the device are glued to a structure. Using the difference of their Young's moduli and coefficients of thermal expansion, both strain and temperature can be measured. The latter sensor is a laminate of two 90° plies of CFRP and an epoxy plate, and an FBG sensor is embedded in the epoxy plate. When the temperature changes, the cross section of the optical fiber is deformed by the thermal residual stress. The deformation of the fiber causes the birefringence and widens the reflection spectrum. Since the temperature can be calculated from the spectrum width, which changes in proportion to the temperature, the accuracy of the strain measurement is improved. The usefulness of these sensors was experimentally confirmed.

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

PubMed

Pegorini, Vinicius; Karam, Leandro Zen; Pitta, Christiano Santos Rocha; Cardoso, Rafael; da Silva, Jean Carlos Cardozo; Kalinowski, Hypolito José; Ribeiro, Richardson; Bertotti, Fábio Luiz; Assmann, Tangriani Simioni

2015-11-11

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. The FBG sensors measure the biomechanical strain during jaw movements, and a decision tree is responsible for the classification of the associated chewing pattern. In this study, patterns associated with food intake of dietary supplement, hay and ryegrass were considered. Additionally, two other important events for ingestive behavior were monitored: rumination and idleness. Experimental results show that the proposed approach for pattern classification is capable of differentiating the five patterns involved in the chewing process with an overall accuracy of 94%.

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

PubMed Central

Pegorini, Vinicius; Karam, Leandro Zen; Pitta, Christiano Santos Rocha; Cardoso, Rafael; da Silva, Jean Carlos Cardozo; Kalinowski, Hypolito José; Ribeiro, Richardson; Bertotti, Fábio Luiz; Assmann, Tangriani Simioni

2015-01-01

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. The FBG sensors measure the biomechanical strain during jaw movements, and a decision tree is responsible for the classification of the associated chewing pattern. In this study, patterns associated with food intake of dietary supplement, hay and ryegrass were considered. Additionally, two other important events for ingestive behavior were monitored: rumination and idleness. Experimental results show that the proposed approach for pattern classification is capable of differentiating the five patterns involved in the chewing process with an overall accuracy of 94%. PMID:26569250

Application of 1D Array FBG Configuration for Impact Localization on Composite Wing under Simulated Noise

DTIC Science & Technology

2016-03-30

Grating Sensor Fundamentals FBG sensors consists of grating with periodic variation in the refractive index which reflects certain wavelengths of...is the grating’s effective refractive index and  is the grating period. Bragg wavelength is sensitive to any changes in strain or temperature...Conference on Composite Materials. 2007: Kyoto, Japan. 2. Cartz, L., Nondestructive Testing: Radiography, Ultrasonics, Liquid Penetrant, Magnetic Particle

Femtosecond Laser Ablated FBG with Composite Microstructure for Hydrogen Sensor Application.

PubMed

Zou, Meng; Dai, Yutang; Zhou, Xian; Dong, Ke; Yang, Minghong

2016-12-01

A composite microstructure in fiber Bragg grating (FBG) with film deposition for hydrogen detection is presented. Through ablated to FBG cladding by a femtosecond laser, straight-trenches and spiral micro-pits are formed. A Pd-Ag film is sputtered on the surface of the laser processed FBG single mode fiber, and acts as hydrogen sensing transducer. The demonstrated experimental outcomes show that a composite structure produced the highest sensitivity of 26.3 pm/%H, nearly sevenfold more sensitive compared with original standard FBG. It offers great potential in engineering applications for its good structure stability and sensitivity.

Impact of Biohybrid Magnetite Nanoparticles and Moroccan Propolis on Adherence of Methicillin Resistant Strains of Staphylococcus aureus.

PubMed

El-Guendouz, Soukaina; Aazza, Smail; Lyoussi, Badiaa; Bankova, Vassya; Lourenço, João P; Costa, Ana M Rosa; Mariano, José F; Miguel, Maria G; Faleiro, Maria L

2016-09-09

Biofilm bacteria are more resistant to antibiotics than planktonic cells. Propolis possesses antimicrobial activity. Generally, nanoparticles containing heavy metals possess antimicrobial and antibiofilm properties. In this study, the ability of adherence of Methicillin Resistant Strains of Staphylococcus aureus (MRSA) to catheters treated with magnetite nanoparticles (MNPs), produced by three methods and functionalized with oleic acid and a hydro-alcoholic extract of propolis from Morocco, was evaluated. The chemical composition of propolis was established by gas chromatography mass spectrometry (GC-MS), and the fabricated nanostructures characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy and Fourrier transform infrared spectroscopy (FTIR). The capacity for impairing biofilm formation was dependent on the strain, as well as on the mode of production of MNPs. The co-precipitation method of MNPs fabrication using Fe(3+) and Na₂SO₃ solution and functionalized with oleic acid and propolis was the most effective in the impairment of adherence of all MRSA strains to catheters (p < 0.001). The adherence of the strain MRSA16 was also significantly lower (p < 0.001) when the catheters were treated with the hybrid MNPs with oleic acid produced by a hydrothermal method. The anti-MRSA observed can be attributed to the presence of benzyl caffeate, pinocembrin, galangin, and isocupressic acid in propolis extract, along with MNPs. However, for MRSA16, the impairment of its adherence on catheters may only be attributed to the hybrid MNPs with oleic acid, since very small amount, if any at all of propolis compounds were added to the MNPs.

FBG Interrogation Method with High Resolution and Response Speed Based on a Reflective-Matched FBG Scheme

PubMed Central

Cui, Jiwen; Hu, Yang; Feng, Kunpeng; Li, Junying; Tan, Jiubin

2015-01-01

In this paper, a high resolution and response speed interrogation method based on a reflective-matched Fiber Bragg Grating (FBG) scheme is investigated in detail. The nonlinear problem of the reflective-matched FBG sensing interrogation scheme is solved by establishing and optimizing the mathematical model. A mechanical adjustment to optimize the interrogation method by tuning the central wavelength of the reference FBG to improve the stability and anti-temperature perturbation performance is investigated. To satisfy the measurement requirements of optical and electric signal processing, a well- designed acquisition circuit board is prepared, and experiments on the performance of the interrogation method are carried out. The experimental results indicate that the optical power resolution of the acquisition circuit border is better than 8 pW, and the stability of the interrogation method with the mechanical adjustment can reach 0.06%. Moreover, the nonlinearity of the interrogation method is 3.3% in the measurable range of 60 pm; the influence of temperature is significantly reduced to 9.5%; the wavelength resolution and response speed can achieve values of 0.3 pm and 500 kHz, respectively. PMID:26184195

Adherence of Moraxella bovis to cell cultures of bovine origin.

PubMed

Annuar, B O; Wilcox, G E

1985-09-01

The adherence of five strains of Moraxella bovis to cell cultures was investigated. M bovis adhered to cultures of bovine corneal epithelial and Madin-Darby bovine kidney cells but not to cell types of non-bovine origin. Both piliated and unpiliated strains adhered but piliated strains adhered to a greater extent than unpiliated strains. Antiserum against pili of one strain inhibited adherence of piliated strains but caused only slight inhibition of adherence to the unpiliated strains. Treatment of bacteria with magnesium chloride caused detachment of pili from the bacterial cell and markedly inhibited adherence of piliated strains but caused only slight inhibition of adherence by the unpiliated strains. The results suggested that adhesion of piliated strains to cell cultures was mediated via pili but that adhesins other than pili may be involved in the attachment of unpiliated strains of M bovis to cells.

Calibration test of the temperature and strain sensitivity coefficient in regional reference grating method

NASA Astrophysics Data System (ADS)

Wu, Jing; Huang, Junbing; Wu, Hanping; Gu, Hongcan; Tang, Bo

2014-12-01

In order to verify the validity of the regional reference grating method in solve the strain/temperature cross sensitive problem in the actual ship structural health monitoring system, and to meet the requirements of engineering, for the sensitivity coefficients of regional reference grating method, national standard measurement equipment is used to calibrate the temperature sensitivity coefficient of selected FBG temperature sensor and strain sensitivity coefficient of FBG strain sensor in this modal. And the thermal expansion sensitivity coefficient of the steel for ships is calibrated with water bath method. The calibration results show that the temperature sensitivity coefficient of FBG temperature sensor is 28.16pm/°C within -10~30°C, and its linearity is greater than 0.999, the strain sensitivity coefficient of FBG strain sensor is 1.32pm/μɛ within -2900~2900μɛ whose linearity is almost to 1, the thermal expansion sensitivity coefficient of the steel for ships is 23.438pm/°C within 30~90°C, and its linearity is greater than 0.998. Finally, the calibration parameters are used in the actual ship structure health monitoring system for temperature compensation. The results show that the effect of temperature compensation is good, and the calibration parameters meet the engineering requirements, which provide an important reference for fiber Bragg grating sensor is widely used in engineering.

Fiber Bragg grating strain sensors to monitor and study active volcanoes

NASA Astrophysics Data System (ADS)

Sorrentino, Fiodor; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvo; Giacomelli, Umberto; Grassi, Renzo; Maccioni, Enrico; Morganti, Mauro

2016-04-01

Stress and strain changes are among the best indicators of impending volcanic activity. In volcano geodesy, borehole volumetric strain-meters are mostly utilized. However, they are not easy to install and involve high implementation costs. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, thus particularly suitable for field application. In the framework of the EC FP7 MED-SUV project, we have developed strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, we have designed a system that is expected to offer a significantly higher resolution and accuracy in static measurements and a smooth dynamic response up to 100 Hz, implying the possibility to observe seismic waves. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to power consumption and to the trade-off between performance and cost. Preliminary field campaigns were carried out on Mt. Etna (Italy) using a prototypal single-axis FBG strain sensor, to check the system performances in out-of-the-lab conditions and in the harsh volcanic environment (lack of mains electricity for power, strong diurnal temperature changes, strong wind, erosive ash, snow and ice during the winter time). We also designed and built a FBG strain sensor featuring a multi-axial configuration which was tested and calibrated in the laboratory. This instrument is suitable for borehole installation and will be tested on Etna soon.

Vibration monitoring of a helicopter blade model using the optical fiber distributed strain sensing technique.

PubMed

Wada, Daichi; Igawa, Hirotaka; Kasai, Tokio

2016-09-01

We demonstrate a dynamic distributed monitoring technique using a long-length fiber Bragg grating (FBG) interrogated by optical frequency domain reflectometry (OFDR) that measures strain at a speed of 150 Hz, spatial resolution of 1 mm, and measurement range of 20 m. A 5 m FBG is bonded to a 5.5 m helicopter blade model, and vibration is applied by the step relaxation method. The time domain responses of the strain distributions are measured, and the blade deflections are calculated based on the strain distributions. Frequency response functions are obtained using the time domain responses of the calculated deflection induced by the preload release, and the modal parameters are retrieved. Experimental results demonstrated the dynamic monitoring performances and the applicability to the modal analysis of the OFDR-FBG technique.

Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices.

PubMed Central

Christensen, G D; Simpson, W A; Younger, J J; Baddour, L M; Barrett, F F; Melton, D M; Beachey, E H

1985-01-01

The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections. Images PMID:3905855

Investigating the Strain, Temperature and Humidity Sensitivity of a Multimode Graded-Index Perfluorinated Polymer Optical Fiber with Bragg Grating

PubMed Central

Zheng, Yulong; Bremer, Kort

2018-01-01

In this work we investigate the strain, temperature and humidity sensitivity of a Fiber Bragg Grating (FBG) inscribed in a near infrared low-loss multimode perfluorinated polymer optical fiber based on cyclic transparent optical polymer (CYTOP). For this purpose, FBGs were inscribed into the multimode CYTOP fiber with a core diameter of 50 µm by using a krypton fluoride (KrF) excimer laser and the phase mask method. The evolution of the reflection spectrum of the FBG detected with a multimode interrogation technique revealed a single reflection peak with a full width at half maximum (FHWM) bandwidth of about 9 nm. Furthermore, the spectral envelope of the single FBG reflection peak can be optimized depending on the KrF excimer laser irradiation time. A linear shift of the Bragg wavelength due to applied strain, temperature and humidity was measured. Furthermore, depending on irradiation time of the KrF excimer laser, both the failure strain and strain sensitivity of the multimode fiber with FBG can be controlled. The inherent low light attenuation in the near infrared wavelength range (telecommunication window) of the multimode CYTOP fiber and the single FBG reflection peak when applying the multimode interrogation set-up will allow for new applications in the area of telecommunication and optical sensing. PMID:29734734

Investigating the Strain, Temperature and Humidity Sensitivity of a Multimode Graded-Index Perfluorinated Polymer Optical Fiber with Bragg Grating.

PubMed

Zheng, Yulong; Bremer, Kort; Roth, Bernhard

2018-05-05

In this work we investigate the strain, temperature and humidity sensitivity of a Fiber Bragg Grating (FBG) inscribed in a near infrared low-loss multimode perfluorinated polymer optical fiber based on cyclic transparent optical polymer (CYTOP). For this purpose, FBGs were inscribed into the multimode CYTOP fiber with a core diameter of 50 µm by using a krypton fluoride (KrF) excimer laser and the phase mask method. The evolution of the reflection spectrum of the FBG detected with a multimode interrogation technique revealed a single reflection peak with a full width at half maximum (FHWM) bandwidth of about 9 nm. Furthermore, the spectral envelope of the single FBG reflection peak can be optimized depending on the KrF excimer laser irradiation time. A linear shift of the Bragg wavelength due to applied strain, temperature and humidity was measured. Furthermore, depending on irradiation time of the KrF excimer laser, both the failure strain and strain sensitivity of the multimode fiber with FBG can be controlled. The inherent low light attenuation in the near infrared wavelength range (telecommunication window) of the multimode CYTOP fiber and the single FBG reflection peak when applying the multimode interrogation set-up will allow for new applications in the area of telecommunication and optical sensing.

Demodulation of a fiber Bragg grating strain sensor by a multiwavelength fiber laser

NASA Astrophysics Data System (ADS)

Cong, Shan; Sun, Yunxu; Zhao, Yuxi; Pan, Lifeng

2012-04-01

A fiber Bragg grating (FBG) sensors system utilizing a multi-wavelength erbium-doped fiber lasers (EDFL) with frequency shifter is proposed. The system is one fiber laser cavity with two FBG sensors as its filters. One is for strain sensing, and the other one is for temperature compensation. A frequency shifter is used to suppress the mode competition to lase two wavelengths that correspond with FBGs. The wavelength shift of the EDFL represents the sensing quantity, which is demodulated by Fiber Fabry-Perot (FFP) filter. The sensor's response to strain is measured by experiment. Because of exploiting the dual-wavelength fiber laser with a frequency shifter forming the feedback as the light source, many advantages of this system are achieved, especially high signal-to-noise ratio, high detected power, and low power consuming comparing with conventional FBG sensor system utilizing broadband light as the light source. What's more, this structure is also easy to combine with FBG array.

Dual-point reflective refractometer based on parallel no-core fiber/FBG structure

NASA Astrophysics Data System (ADS)

Guo, Cuijuan; Niu, Panpan; Wang, Juan; Zhao, Junfa; Zhang, Cheng

2018-01-01

A novel dual-point reflective fiber-optic refractometer based on multimode interference (MMI) effect and fiber Bragg grating (FBG) reflection is proposed and experimentally demonstrated, which adopts parallel structure. Each point of the refractometer consists of a single mode-no core-single mode fiber (SNS) structure cascaded with a FBG. Assisted by the reflection of FBG, refractive index (RI) measurement can be achieved by monitoring the peak power variation of the reflected FBG spectrum. By selecting different length of the no core fiber and center wavelength of the FBG, independent dual-point refractometer is easily realized. Experiment results show that the refractometer has a nonlinear relationship between the surrounding refractive index (SRI) and the peak power of the reflected FBG spectrum in the RI range of 1.3330-1.4086. Linear relationship can be approximately obtained by dividing the measuring range into 1.3330-1.3611 and 1.3764-1.4086. In the RI range of 1.3764-1.4086, the two sensing points have higher RI sensitivities of 319.34 dB/RIU and 211.84 dB/RIU, respectively.

FBG Interrogation Method with High Resolution and Response Speed Based on a Reflective-Matched FBG Scheme.

PubMed

Cui, Jiwen; Hu, Yang; Feng, Kunpeng; Li, Junying; Tan, Jiubin

2015-07-08

In this paper, a high resolution and response speed interrogation method based on a reflective-matched Fiber Bragg Grating (FBG) scheme is investigated in detail. The nonlinear problem of the reflective-matched FBG sensing interrogation scheme is solved by establishing and optimizing the mathematical model. A mechanical adjustment to optimize the interrogation method by tuning the central wavelength of the reference FBG to improve the stability and anti-temperature perturbation performance is investigated. To satisfy the measurement requirements of optical and electric signal processing, a well- designed acquisition circuit board is prepared, and experiments on the performance of the interrogation method are carried out. The experimental results indicate that the optical power resolution of the acquisition circuit border is better than 8 pW, and the stability of the interrogation method with the mechanical adjustment can reach 0.06%. Moreover, the nonlinearity of the interrogation method is 3.3% in the measurable range of 60 pm; the influence of temperature is significantly reduced to 9.5%; the wavelength resolution and response speed can achieve values of 0.3 pm and 500 kHz, respectively.

Investigation on a fiber optic accelerometer based on FBG-FP interferometer

NASA Astrophysics Data System (ADS)

Lin, Chongyu; Luo, Hong; Xiong, Shuidong; Li, Haitao

2014-12-01

A fiber optic accelerometer based on fiber Bragg grating Fabry-Perot (FBG-FP) interferometer is presented. The sensor is a FBG-FP cavity which is formed with two weak fiber Bragg gratings (FBGs) in a single-mode fiber. The reflectivity of the two FBGs is 9.42% and 7.74% respectively, and the fiber between them is 10 meters long. An optical demodulation system was set up to analyze the reflected light of FBG-FP cavity. Acceleration signals of different frequencies and intensities were demodulated correctly and stably by the system. Based on analyzing the optical spectrum of weak FBG based FBG-FP cavity, we got the equivalent length of FBG-FP cavity. We used a path-matching Michelson interferometer (MI) to demodulate the acceleration signal. The visibility of the interference fringe we got was 41%~42% while the theory limit was 50%. This indicated that the difference of interferometer's two arms and the equivalent length of FBG-FP cavity were matched well. Phase generated carrier (PGC) technology was used to eliminate phase fading caused by random phase shift and Faraday rotation mirrors (FRMs) were used to eliminate polarization-induced phase fading. The accelerometer used a compliant cylinder design and its' sensitivity and frequency response were analyzed and simulated based on elastic mechanics. Experiment result showed that the accelerometer had a flat frequency response over the frequency range of 31-630Hz. The sensitivity was about 31dB (0dB=1rad/g) with fluctuation less than 1.5dB.

Laser interrogation techniques for high-sensitivity strain sensing by fiber-Bragg-grating structures

NASA Astrophysics Data System (ADS)

Gagliardi, G.; Salza, M.; Ferraro, P.; De Natale, P.

2017-11-01

Novel interrogation methods for static and dynamic measurements of mechanical deformations by fiber Bragg-gratings (FBGs) structures are presented. The sensor-reflected radiation gives information on suffered strain, with a sensitivity dependent on the interrogation setup. Different approaches have been carried out, based on laser-frequency modulation techniques and near-IR lasers, to measure strain in single-FBG and in resonant high-reflectivity FBG arrays. In particular, for the fiber resonator, the laser frequency is actively locked to the cavity resonances by the Pound-Drever-Hall technique, thus tracking any frequency change due to deformations. The loop error and correction signals fed back to the laser are used as strain monitor. Sensitivity limits vary between 200 nɛ/√Hz in the quasi-static domain (0.5÷2 Hz), and between 1 and 4 nɛ/√Hz in the 0.4-1 kHz range for the single-FBG scheme, while strain down to 50 pɛ can be detected by using the laser-cavity-locked method.

Large strain detection of SRM composite shell based on fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Zhang, Lei; Chang, Xinlong; Zhang, Youhong; Yang, Fan

2017-12-01

There may be more than 2% strain of carbon fiber composite material on solid rocket motor (SRM) in some extreme cases. A surface-bonded silica fiber Bragg grating (FBG) strain sensor coated by polymer is designed to detect the large strain of composite material. The strain transfer relation of the FBG large strain sensor is deduced, and the strain transfer mechanism is verified by finite element simulation. To calibrate the sensors, the tensile test is done by using the carbon fiber composite plate specimen attached to the designed strain sensor. The results show that the designed sensor can detect the strain more than 3%, the strain sensitivity is 0.0762 pm/μɛ, the resolution is 13.13μɛ, and the fitting degree of the wavelength-strain curve fitting function is 0.9988. The accuracy and linearity of the sensor can meet the engineering requirements.

[Progressive damage monitoring of corrugated composite skins by the FBG spectral characteristics].

PubMed

Zhang, Yong; Wang, Bang-Feng; Lu, Ji-Yun; Gu, Li-Li; Su, Yong-Gang

2014-03-01

In the present paper, a method of monitoring progressive damage of composite structures by non-uniform fiber Bragg grating (FBG) reflection spectrum is proposed. Due to the finite element analysis of corrugated composite skins specimens, the failure process under tensile load and corresponding critical failure loads of corrugated composite skin was predicated. Then, the non-uniform reflection spectrum of FBG sensor could be reconstructed and the corresponding relationship between layer failure order sequence of corrugated composite skin and FBG sensor reflection spectrums was acquired. A monitoring system based on FBG non-uniform reflection spectrum, which can be used to monitor progressive damage of corrugated composite skins, was built. The corrugated composite skins were stretched under this FBG non-uniform reflection spectrum monitoring system. The results indicate that real-time spectrums acquired by FBG non-uniform reflection spectrum monitoring system show the same trend with the reconstruction reflection spectrums. The maximum error between the corresponding failure and the predictive value is 8.6%, which proves the feasibility of using FBG sensor to monitor progressive damage of corrugated composite skin. In this method, the real-time changes in the FBG non-uniform reflection spectrum within the scope of failure were acquired through the way of monitoring and predicating, and at the same time, the progressive damage extent and layer failure sequence of corru- gated composite skin was estimated, and without destroying the structure of the specimen, the method is easy and simple to operate. The measurement and transmission section of the system are completely composed of optical fiber, which provides new ideas and experimental reference for the field of dynamic monitoring of smart skin.

Curli Temper Adherence of Escherichia coli O157:H7 to Squamous Epithelial Cells from the Bovine Recto-Anal Junction in a Strain-Dependent Manner

PubMed Central

Carter, Michelle Q.; Sharma, Vijay K.; Stasko, Judith A.; Giron, Jorge A.

2016-01-01

ABSTRACT Our recent studies have shown that intimin and the locus of enterocyte effacement-encoded proteins do not play a role in Escherichia coli O157:H7 (O157) adherence to the bovine recto-anal junction squamous epithelial (RSE) cells. To define factors that play a contributory role, we investigated the role of curli, fimbrial adhesins commonly implicated in adherence to various fomites and plant and human epithelial cells, in O157 adherence to RSE cells. Specifically, we examined (i) wild-type strains of O157; (ii) curli variants of O157 strains; (iii) isogenic curli deletion mutants of O157; and (iv) adherence inhibition of O157 using anti-curlin sera. Results of these experiments conducted under stringent conditions suggest that curli do not solely contribute to O157 adherence to RSE cells and in fact demonstrate a modulating effect on O157 adherence to RSE cells in contrast to HEp-2 cells (human epidermoid carcinoma of the larynx cells with HeLa contamination). The absence of curli and presence of blocking anti-curli antibodies enhanced O157-RSE cell interactions among some strains, thus alluding to a spatial, tempering effect of curli on O157 adherence to RSE cells when present. At the same time, the presence or absence of curli did not alter RSE cell adherence patterns of another O157 strain. These observations are at variance with the reported role of curli in O157 adherence to human cell lines such as HEp-2 and need to be factored in when developing anti-adherence modalities for preharvest control of O157 in cattle. IMPORTANCE This study demonstrated that O157 strains interact with epithelial cells in a host-specific manner. The fimbriae/adhesins that are significant for adherence to human cell lines may not have a role or may have a modulating role in O157 adherence to bovine cells. Targeting such adhesins may not prevent O157 attachment to bovine cells but instead may result in improved adherence. Hence, conducting host-specific evaluations is critical

FBG-Based Monitoring of Geohazards: Current Status and Trends

PubMed Central

Zhu, Hong-Hu; Shi, Bin; Zhang, Cheng-Cheng

2017-01-01

In recent years, natural and anthropogenic geohazards have occured frequently all over the world, and field monitoring is becoming an increasingly important task to mitigate these risks. However, conventional geotechnical instrumentations for monitoring geohazards have a number of weaknesses, such as low accuracy, poor durability, and high sensitivity to environmental interferences. In this aspect, fiber Bragg grating (FBG), as a popular fiber optic sensing technology, has gained an explosive amount of attention. Based on this technology, quasi-distributed sensing systems have been established to perform real-time monitoring and early warning of landslides, debris flows, land subsidence, earth fissures and so on. In this paper, the recent research and development activities of applying FBG systems to monitor different types of geohazards, especially those triggered by human activities, are critically reviewed. The working principles of newly developed FBG sensors are briefly introduced, and their features are summarized. This is followed by a discussion of recent case studies and lessons learned, and some critical problems associated with field implementation of FBG-based monitoring systems. Finally the challenges and future trends in this research area are presented. PMID:28245551

FBG-Based Monitoring of Geohazards: Current Status and Trends.

PubMed

Zhu, Hong-Hu; Shi, Bin; Zhang, Cheng-Cheng

2017-02-24

In recent years, natural and anthropogenic geohazards have occured frequently all over the world, and field monitoring is becoming an increasingly important task to mitigate these risks. However, conventional geotechnical instrumentations for monitoring geohazards have a number of weaknesses, such as low accuracy, poor durability, and high sensitivity to environmental interferences. In this aspect, fiber Bragg grating (FBG), as a popular fiber optic sensing technology, has gained an explosive amount of attention. Based on this technology, quasi-distributed sensing systems have been established to perform real-time monitoring and early warning of landslides, debris flows, land subsidence, earth fissures and so on. In this paper, the recent research and development activities of applying FBG systems to monitor different types of geohazards, especially those triggered by human activities, are critically reviewed. The working principles of newly developed FBG sensors are briefly introduced, and their features are summarized. This is followed by a discussion of recent case studies and lessons learned, and some critical problems associated with field implementation of FBG-based monitoring systems. Finally the challenges and future trends in this research area are presented.

Strain Measurement Using FBG on COPV in Stress Rupture Test

NASA Technical Reports Server (NTRS)

Banks, Curtis; Grant, Joseph

2007-01-01

to better predict the remaining life of the STS COPVs. The primary test objective is obtaining data to verify the hypothesis of a radially oriented thru-thickness stress-riser in the COPV composite whose magnitude is a function of the applied pressure and the load history. The anticipated load dependent response follows from the constitutive behavior of the composite overwrap so data to quantify its nonlinear and time dependent response will be sought. The objective of the Fiber Braggs Gratings (FBGs) were to advance the state-of-the-art by developing techniques using FBG sensors that are capable of assessing stress-rupture degradation in Kevlar COPVs in a health monitoring mode (1). Moreover, they sought to answer questions of how embedded sensors affect overall integrity of the structure. And lastly, they sought to provide an important link in the overall stress rupture study that will help close the loop on the COPV fabrication process. NDE inspection methods will be used from start to finish and FBG will be an integral link within the overall chain.

Complete Genome Sequence of the Crohn's Disease-Associated Adherent-Invasive Escherichia coliStrain HM605▿

PubMed Central

Clarke, David J.; Chaudhuri, Roy R.; Martin, Helen M.; Campbell, Barry J.; Rhodes, Jonathan M.; Constantinidou, Chrystala; Pallen, Mark J.; Loman, Nicholas J.; Cunningham, Adam F.; Browning, Douglas F.; Henderson, Ian R.

2011-01-01

Adherent-invasive Escherichia colistrains are increasingly being associated with intestinal pathologies. Here we present the genome sequence of E. coliHM605, a strain isolated from colonic biopsy specimens of a patient with Crohn's disease. PMID:21705601

One novel type of miniaturization FBG rotation angle sensor with high measurement precision and temperature self-compensation

NASA Astrophysics Data System (ADS)

Jiang, Shanchao; Wang, Jing; Sui, Qingmei

2018-03-01

In order to achieve rotation angle measurement, one novel type of miniaturization fiber Bragg grating (FBG) rotation angle sensor with high measurement precision and temperature self-compensation is proposed and studied in this paper. The FBG rotation angle sensor mainly contains two core sensitivity elements (FBG1 and FBG2), triangular cantilever beam, and rotation angle transfer element. In theory, the proposed sensor can achieve temperature self-compensation by complementation of the two core sensitivity elements (FBG1 and FBG2), and it has a boundless angel measurement range with 2π rad period duo to the function of the rotation angle transfer element. Based on introducing the joint working processes, the theory calculation model of the FBG rotation angel sensor is established, and the calibration experiment on one prototype is also carried out to obtain its measurement performance. After experimental data analyses, the measurement precision of the FBG rotation angle sensor prototype is 0.2 ° with excellent linearity, and the temperature sensitivities of FBG1 and FBG2 are 10 pm/° and 10.1 pm/°, correspondingly. All these experimental results confirm that the FBG rotation angle sensor can achieve large-range angle measurement with high precision and temperature self-compensation.

On the Effects of the Lateral Strains on the Fiber Bragg Grating Response

PubMed Central

Lai, Marco; Karalekas, Dimitris; Botsis, John

2013-01-01

In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with no constrains on planes normal to the embedded sensor's axis is biaxially loaded, (b) when the same isotropic host material is subjected to hydrostatic pressure and (c) when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite. PMID:23429580

Field monitoring of static, dynamic, and statnamic pile loading tests using fibre Bragg grating strain sensors

NASA Astrophysics Data System (ADS)

Li, Jin; Correia, Ricardo P.; Chehura, Edmon; Staines, Stephen; James, Stephen W.; Tatam, Ralph; Butcher, Antony P.; Fuentes, Raul

2009-10-01

Pile loading test plays an important role in the field of piling engineering. In order to gain further insight into the load transfer mechanism, strain gauges are often used to measure local strains along the piles. This paper reports a case whereby FBG strain sensors was employed in a field trial conducted on three different types of pile loading tests in a glacial till. The instrumentation systems were configured to suit the specific characteristic of each type of test. Typical test results are presented. The great potential of using FBG sensors for pile testing is shown.

Analysis and experimental study on the strain transfer mechanism of an embedded basalt fiber-encapsulated fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Zhang, Zhenglin; Wang, Yuan; Sun, Yangyang; Zhang, Qinghua; You, Zewei; Huang, Xiaodi

2017-01-01

The precision of the encapsulated fiber optic sensor embedded into a host suffers from the influences of encapsulating materials. Furthermore, an interface transfer effect of strain sensing exists. This study uses an embedded basalt fiber-encapsulated fiber Bragg grating (FBG) sensor as the research object to derive an expression in a multilayer interface strain transfer coefficient by considering the mechanical properties of the host material. The direct impact of the host material on the strain transfer at an embedded multipoint continuous FBG (i.e., multiple gratings written on a single optical fiber) monitoring strain sensor, which was self-developed and encapsulated with basalt fiber, is studied to present the strain transfer coefficients corresponding to the positions of various gratings. The strain transfer coefficients of the sensor are analyzed based on the experiments designed for this study. The error of the experimental results is ˜2 μɛ when the strain is at 60 μɛ and below. Moreover, the measured curves almost completely coincide with the theoretical curves. The changes in the internal strain field inside the embedded structure of the basalt fiber-encapsulated FBG strain sensor could be easily monitored. Hence, important references are provided to measure the internal stress strain of the sensor.

Thermal Curing Process Monitoring of the Composite Material Using the FBG sensor

NASA Astrophysics Data System (ADS)

Zhang, Youhong; Chang, Xinlong; Zhang, Xiaojun; He, Xiangyong

2018-03-01

The raw composite material will suffer complex chemical and morphological changes during the thermal curing process, and it is difficult to monitor the curing process and curing effect. In this paper, the FBG sensor was embedded in the raw composite material to monitor the whole curing process. The experiment results showed that the FBG sensor can monitor the resin transformation and residual deformation of the composite material, and the FBG sensor can be applied to monitor the thermal curing process of the composite structure.

In the trail of a new bio-sensor for measuring strain in bone: osteoblastic biocompatibility.

PubMed

Carvalho, Lídia; Alberto, Nélia J; Gomes, Pedro S; Nogueira, Rogério N; Pinto, João L; Fernandes, Maria H

2011-06-15

Fibre Bragg Grating (FBG) is an optical sensor recorded within the core of a standard optical fibre, which responds faithfully to strain and temperature. FBG sensors are a promising alternative to other sensing methodologies to assess bone mechanics in vivo. However, response of bone cells/bone tissue to FBGs and its sensing capability in this environment have not been recorded yet. The present study addressed these issues in long-term human osteoblastic cell cultures. Results showed that osteoblastic cells were able to adhere and proliferate over the fibre and, also, the protective polymer coating. RT-PCR analysis showed the expression of Col I, ALP, BMP-2, M-CSF, RANKL and OPG. In addition, cultures presented high ALP activity and the formation of a calcium phosphate mineralized extracellular matrix. Cell behavior over the fibre without and with the coating polymer was similar to that found in cultures grown in standard tissue culture plates (control). In addition to the excellent osteoblastic cytocompatibility, FBGs maintained the physical integrity and functionality, as its sensing capability was not affected through the culture period. Results suggest the possibility of in vivo osseointegration of the optical fibre/FBGs anticipating a variety of applications in bone mechanical dynamics. Copyright © 2011 Elsevier B.V. All rights reserved.

Application of small-diameter FBG sensors for detection of damages in composites

NASA Astrophysics Data System (ADS)

Okabe, Yoji; Mizutani, Tadahito; Yashiro, Shigeki; Takeda, Nobuo

2001-08-01

Small-diameter fiber Bragg grating (FBG) sensors have been developed by Hitachi Cable Ltd. and the authors. Since the outside diameter of polyimide coating is 52 micrometers , embedding of the sensors into carbon fiber reinforced plastic (CFRP) composites prepregs of 125 micrometers in thickness does not deteriorate the mechanical properties of the composite laminates. In this research, the small-diameter FBG sensor was applied for the detection of transverse cracks in CFRP composites. The FBG sensor was embedded in 0 degree(s) ply of a CFRP cross-ply laminate.

Microstructured FBG hydrogen sensor based on Pt-loaded WO₃.

PubMed

Zhou, Xian; Dai, Yutang; Karanja, Joseph Muna; Liu, Fufei; Yang, Minghong

2017-04-17

Hydrogen gas sensing properties of Pt-WO₃ films on spiral microstructured fiber Bragg grating (FBG) has been demonstrated. Pt-WO₃ film was prepared by hydrothermal method. The spiral microsturctured FBG was fabricated using femtosecond laser. Spiral microstructure FBG hydrogen sensor can detect hydrogen concentration from 0.02% H₂ to 4% H₂ at room temperature, and the response time is shortened from a few minutes to 10~30 s. Double spiral microstructure at pitch 60 μm and sputtered with 2 μm Pt-WO₃ film recorded hydrogen sensitivity of 522 pm/%(v/v) H₂ responding to hydrogen gas in air. This translated to approximately 2~4 times higher than the unprocessed standard FBG. The humidity has little effect on the sensing property. The sensor has fast response time, good stability, large detection range and has the good prospect of practical application for hydrogen leak detection.

Surface-layer (S-layer) of human and animal Clostridium difficile strains and their behaviour in adherence to epithelial cells and intestinal colonization.

PubMed

Spigaglia, Patrizia; Barketi-Klai, Amira; Collignon, Anne; Mastrantonio, Paola; Barbanti, Fabrizio; Rupnik, Maja; Janezic, Sandra; Kansau, Imad

2013-09-01

Clostridium difficile is a frequent cause of severe, recurrent post-antibiotic diarrhoea and pseudomembranous colitis. The surface layer (S-layer) is the predominant outer surface component of C. difficile which is involved in pathogen-host interactions critical to pathogenesis. In this study, we characterized the S-layer protein A (SlpA) of animal and human strains belonging to different PCR-ribotypes (PR) and compared the in vitro adherence and in vivo colonization properties of strains showing different SlpA variants. Since each SlpA variant has been recently associated with an S-layer cassette, we were able to deduce the cassette for each of our strains. In this study, an identity of 99-100 % was found among the SlpA of isolates belonging to PR 012, 014/020, 045 and 078. One exception was the SlpA of a poultry isolate, PR 014/020, which showed 99 % identity with that of strain 0160, another PR 014/020 which contains an S-layer cassette 6. Interestingly, this cassette has also been found in a PR 018 strain, an emerging virulent type currently predominant in Italy. Five other SlpA variants (v014/020a-e) were identified in strains PR 014/020. In vitro adherence assays and in vivo colonization experiments were performed on five PR 014/020 strains: human 1064 (v014/020e), human 4684/08 (v014/020b), human IT1106 (v078a), poultry P30 (v014/020d) and poultry PB90 (v014/020b) strains. Adhesion assays indicate that C. difficile strains vary in their capacity to adhere to cells in culture and that adhesion seems to be independent of the SlpA variant. Colonization properties were assessed in vivo using a dixenic mouse model of colonization. The kinetics of faecal shedding and caecal colonization were similar when human 4684/08 (v014/020b) strain was compared with human 1064 (v014/020e) and poultry PB90 (v014/020b) strain. In contrast, poultry P30 (v014/020d) strain outcompeted both human 4684/08 (v014/020b) and IT1106 (v078a) strains and its adherence to caeca at day 7 was

High resolution interrogation system for fiber Bragg grating (FBG) sensor application using radio frequency spectrum analyser

NASA Astrophysics Data System (ADS)

Muhammad, F. D.; Zulkifli, M. Z.; Harun, S. W.; Ahmad, H.

2013-05-01

In this paper, we propose a fiber Bragg grating (FBG) interrogation system for high resolution sensor application based on radio frequency (RF) generation technique by beating a single longitudinal mode (SLM) fiber ring laser with an external tunable laser source (TLS). The external TLS provides a constant wavelength (CW), functioning as the reference signal for the frequency beating technique. The TLS used has a constant output power and wavelength over time. The sensor signal is provided by the reflected wavelength of a typical fiber Bragg grating (FBG) in the SLM fiber ring laser, which consists of a 1 m long highly doped Erbium doped fiber as the gain medium. The key to ensure the SLM laser oscillation is the role of graphene as saturable absorber which is opposed to the commonly used unpumped erbiumdoped fiber and this consequently contributes to the simple and short cavity design of our proposed system. The signal from the SLM fiber ring laser, which is generated by the FBG in response to external changes, such as temperature, strain, air humidity and air movement, is heterodyned with the CW signal from the TLS at a 6 GHz photodetector using a 3-dB fused coupler to generate the frequency beating. This proposed system is experimentally demonstrated as a temperature sensor and the results shows that the frequency response of the system towards the changes in temperature is about 1.3 GHz/°C, taking into account the resolution bandwidth of 3 MHz of the radio frequency spectrum analyzer (RFSA).

Influence of subinhibitory antibiotic concentration on Streptococcus pyogenes adherence and biofilm production.

PubMed

Šmitran, Aleksandra; Vuković, Dragana; Opavski, Nataša; Gajić, Ina; Marinković, Jelena; Božić, Ljiljana; Živanović, Irena; Kekić, Dušan; Popović, Sunčica; Ranin, Lazar

2018-06-01

In this study, the focus was on the effects of sub-MICs of the antibiotics on adherence, hydrophobicity, and biofilm formation by two groups of Streptococcus pyogenes strains, which were responsible for different clinical cases. The aim of this study was to explore the effects of sub-MICs of penicillin, ceftriaxone, erythromycin, and clindamycin on adherence, surface hydrophobicity, and biofilm biomass in two selected collections of group A streptococcus (GAS): strains isolated from carriers (CA) and strains isolated from patients with tonsillopharyngitis (TPh). Isolates were tested for hydrophobicity to xylene, adherence, and biofilm production in uncoated microtiter plates before and after treatment with 1/2 and 1/4 MICs of antibiotics. Penicillin reduced adherence and biofilm production in TPh strains, whereas ceftriaxone diminished adherence and biofilm formation in CA group. On the contrary, clindamycin enhanced adherence and biofilm production in both groups of strains. Erythromycin did not significantly alter adherence, but triggered biofilm production in both groups of isolates. Hydrophobicity of both groups of strains was significantly reduced after exposure to all antibiotics. Beta-lactams displayed anti-biofilm activity; penicillin diminished both adherence and biofilm production in TPh strains, whereas ceftriaxone reduced it in strains isolated from CA.

Pathogenic and Nonpathogenic Strains of Entamoeba histolytica can be Differentiated by Monoclonal Antibodies to the Galactose-Specific Adherence Lectin

DTIC Science & Technology

1991-04-01

AD- A235 913 DEVELOPMENT Ei ENGINEERING CENTER CRDEC-TR-268 PATHOGENIC AND NONPATHOGENIC STRAINS OF ENTAMOEBA HISTOLYTICA CAN BE DIFFERENTIATED BY...Pathogenic and Nonpathogenic Strains of Entamoeba Histolytica can be Differentiated by Monoclonal PR-IFJlX2XXRPEW Antibodies to the Galactose-Specific...galactose lectin produced by Entamoeba histolytica provide the basis for development of a model system for the environmental detection of adherence and

Comparison of the FBG sensor encapsulated into PDMS and FBG sensor glued on the plexiglass pad for respiratory and heart rate monitoring

NASA Astrophysics Data System (ADS)

Fajkus, Marcel; Nedoma, Jan; Martinek, Radek; Walendziuk, Wojciech

2017-08-01

Authors of this article focused on the use of fiber-optic technology for monitoring heart and respiratory rate of the human body. The article describes an innovative method of encapsulating fiber Bragg grating (FBG) into polymer polydimethylsiloxane (PDMS) and comparison of this measuring probe with an FBG sensor glued on the plexiglass pad. The team of authors offers a solution which is basically focused on the monitoring of long-term ill patients with a minimum of physical movement load. Real data were acquired from a group of 10 volunteers with their written consent in the laboratory environment. Acquired data was compared by the Bland-Altman method.

Simultaneous measurement of absolute strain and differential strain based on fiber Bragg grating Fabry-Perot sensor

NASA Astrophysics Data System (ADS)

Wang, Kuiru; Wang, Bo; Yan, Binbin; Sang, Xinzhu; Yuan, Jinhui; Peng, Gang-Ding

2013-10-01

We present a fiber Bragg grating Fabry-Perot (FBG-FP) sensor using the fast Fourier transform (FFT) demodulation for measuring the absolute strain and differential strain simultaneously. The amplitude and phase characteristics of Fourier transform spectrum have been studied. The relation between the amplitude of Fourier spectrum and the differential strain has been presented. We fabricate the fiber grating FP cavity sensor, and carry out the experiment on the measurement of absolute strain and differential strain. Experimental results verify the demodulation method, and show that this sensor has a good accuracy in the scope of measurement. The demodulating method can expand the number of multiplexed sensors combining with wavelength division multiplexing and time division multiplexing.

Simultaneous measurement of temperature and strain using a phase-shifted fiber Bragg grating inscribed by femtosecond laser

NASA Astrophysics Data System (ADS)

Jiang, Yajun; Liu, Chi; Li, Dong; Yang, Dexing; Zhao, Jianlin

2018-04-01

A novel method for simultaneous measurement of temperature and strain using a single phase-shifted fiber Bragg grating (PS-FBG) is proposed. The PS-FBG is produced by exposing the fusion-spliced fiber with a femtosecond laser and uniform phase mask. Due to the non-uniform structure and strain distribution in the fusion-spliced region, the phase-shift changes with different responses during increases to the temperature and strain; by measuring the central wavelengths and the loss difference of two transmission dips, temperature and strain can be determined simultaneously. The resolutions of this particular sensor in measuring temperature and strain are estimated to be  ±1.5 °C and  ±12.2 µɛ in a range from  -50 °C to 150 °C and from 0 µɛ to 2070 µɛ.

Interferometric visualization and demodulation method for measuring quasi-static strain in fiber Bragg grating sensors by a simple rotating etalon filter

NASA Astrophysics Data System (ADS)

Rocco, Alessandra S.; Coppola, Giuseppe; Ferraro, Pietro; Foti, Giuseppe; Iodice, Mario

2004-09-01

Optical fiber sensors are the ideal system to monitor "smart structures" and on-site/real time stress measurements: they can be in fact easily embedded or attached to the structures under test and are not affected by electro- magnetic noise. In particular a signal from a Fiber Bragg grating sensor (FBG) may be processed such that its information remains immune to optical power fluctuations. Different interrogation methods can be used for reading out Bragg wavelength shifts. In this paper we propose a very simple interferometric method for interrogating FBG sensors, based on bi-polished silicon sample acting like an etalon tuneable filter (ETF). The Bragg wavelength shift can be evaluated by analyzing the spectral response of signal reflected by the FBG sensor and filtered by the ETF that is continuously and rapidly tuned. Tuning was obtained by rotating the ETF. Variation in the strain at the FBG causes a phase shift in the analyzed signal. The overall spectral signal, collected with time, consists in an interferometric figure which finesse and fringe contrast depending on the geometrical sizes and facets reflectivity of the silicon sample. The fringe pattern, expressed by the Airy's formula, depends on the wavelength l of the incident radiation and on the angle of incidence. The phase of fringe pattern can be retrieved by a standard FFT method giving quantitative measurements of the quasi-static strain variation sensed by the FBG. In this way, the method allows a valuable visualization of the time-evolution of the incremental strain applied to the FBG. Principle of functioning of this method is described and first results obtained employing such configuration, are reported.

Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil

PubMed Central

Luo, Ying-Ting; Wang, Hong-Bin; Ma, Guo-Ming; Song, Hong-Tu; Li, Chengrong; Jiang, Jun

2016-01-01

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis. PMID:27782034

Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil.

PubMed

Luo, Ying-Ting; Wang, Hong-Bin; Ma, Guo-Ming; Song, Hong-Tu; Li, Chengrong; Jiang, Jun

2016-10-04

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis.

Asymmetric transmission and reflection spectra of FBG in single-multi-single mode fiber structure.

PubMed

Chai, Quan; Liu, Yanlei; Zhang, Jianzhong; Yang, Jun; Chen, Yujin; Yuan, Libo; Peng, Gang-Ding

2015-05-04

We give a comprehensive theoretical analysis and simulation of a FBG in single-multi-single mode fiber structure (FBG-in-SMS), based on the coupled mode analysis and the mode interference analysis. This enables us to explain the experimental observations, its asymmetric transmission and reflection spectra with the similar temperature responses near the spectral range of Bragg wavelengths. The transmission spectrum shift during FBG written-in process is observed and discussed. The analysis results are useful in the design of the SMS structure based sensors and filters.

The adherent abilities of Clostridium perfringens strains are critical for the pathogenesis of avian necrotic enteritis.

PubMed

Wade, Ben; Keyburn, Anthony L; Haring, Volker; Ford, Mark; Rood, Julian I; Moore, Robert J

2016-12-25

Necrotic enteritis of poultry is an emerging disease of substantial economic importance, but aspects of the pathogenesis of this multi-factorial disease are still unclear. We recently demonstrated that the ability of avian strains of the causative bacterium, Clostridium perfringens, to bind to specific collagen types correlated strongly with their virulence and we postulated that binding of the pathogen to collagen types IV and V and gelatin may involve the putative adhesin-encoding gene cnaA, which is found in the VR-10B locus. In this study we have used site-directed mutagenesis to demonstrate that disruption of the cnaA gene leads to a reduction in the expression of the three genes immediately downstream of cnaA and reduced adherence to collagen types IV and V and gelatin. In addition, a cnaA mutant of strain EHE-NE18 was no longer capable of causing necrotic enteritis in a chicken disease induction model and had a significantly reduced ability to colonise the chicken intestinal mucosa. These results were confirmed by generating and analysing a similar mutant in an independent necrotic enteritis causing C. perfringens strain. This study expands our understanding of the mechanisms involved in necrotic enteritis pathogenesis by demonstrating the importance of C. perfringens adherence to extracellular matrix proteins. Copyright © 2016. Published by Elsevier B.V.

FIBER BRAGG GRATING SENSORS FOR LOCALIZED STRAIN MEASUREMENTS AT LOW TEMPERATURE AND IN HIGH MAGNETIC FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramalingam, Rajinikumar

2010-04-09

Study of magnetostrictive effects in the bulk superconductors is very essential and can give more knowledge about the effects like namely, flux pinning induced strain, pincushion distortions in the magnets and so on. Currently used electro mechanical sensors are magnetic field dependent and can only give the global stress/strain information but not the local stress/strains. But the information like radius position dependent strain and characterisation of shape distortion in non cylindrical magnets are interesting. Wavelength encoded multiplexed fiber Bragg Grating sensors inscribed in one fiber gives the possibility to measure magentostrictive effects spatially resolved in low temperature and high magneticmore » field. This paper specifies the design and technology requirements to adapt FBG sensors for such an application. Also reports the experiments demonstrate the properties of glass FBG at low temperature (4.2 K) and the results of strain measurement at 4.2 K/8 T. The sensor exhibits a linear wavelength change for the strain change.« less

Strain dependence of perfluorinated polymer optical fiber Bragg grating measured at different wavelengths

NASA Astrophysics Data System (ADS)

Ishikawa, Ryo; Lee, Heeyoung; Lacraz, Amédée; Theodosiou, Antreas; Kalli, Kyriacos; Mizuno, Yosuke; Nakamura, Kentaro

2018-03-01

We measure the strain dependence of multiple Bragg wavelengths (corresponding to different diffraction orders) of a fiber Bragg grating (FBG) inscribed in a perfluorinated graded-index polymer optical fiber (PFGI-POF) in the wavelength range up to 1550 nm. On the basis of this result, we show that the fractional sensitivity, which has been conventionally used as a wavelength-independent index for fair comparison of the FBG performance measured at different wavelengths, is dependent on wavelength in this range. The reason for this behavior seems to originate from the non-negligible wavelength dependence of refractive index and its strain-dependence coefficient. Using the wavelength dependence of the refractive index already reported for bulk, we deduce the wavelength dependence of the strain coefficient of the refractive index. This information will be a useful archive in implementing PFGI-POF-based strain sensors based on not only FBGs but also Brillouin scattering in the future.

Spatial Compressive Sensing for Strain Data Reconstruction from Sparse Sensors

DTIC Science & Technology

2014-10-01

optical fiber Bragg grating (or FBG ) sensors embedded in the plate. For the sake of simplicity, we assume that the FBGs are embedded in the radial...direction, as shown by the yellow lines in Fig. 10. The yellow lines are the direction along which strain is being measured. We considered FBGs here...however, strain gages emplaced along these lines can also be envisioned. FBGs are strain-measuring sensors that use the principle of low coherence

Bacterial adherence to anodized titanium alloy

NASA Astrophysics Data System (ADS)

Pérez-Jorge Peremarch, C.; Pérez Tanoira, R.; Arenas, M. A.; Matykina, E.; Conde, A.; De Damborenea, J. J.; Gómez Barrena, E.; Esteban, J.

2010-11-01

The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

Dynamic fiber Bragg grating strain sensor interrogation with real-time measurement

NASA Astrophysics Data System (ADS)

Park, Jinwoo; Kwon, Yong Seok; Ko, Myeong Ock; Jeon, Min Yong

2017-11-01

We demonstrate a 1550 nm band resonance Fourier-domain mode-locked (FDML) fiber laser with fiber Bragg grating (FBG) array. Using the FDML fiber laser, we successfully demonstrate real-time monitoring of dynamic FBG strain sensor interrogation for structural health monitoring. The resonance FDML fiber laser consists of six multiplexed FBGs, which are arranged in series with delay fiber lengths. It is operated by driving the fiber Fabry-Perot tunable filter (FFP-TF) with a sinusoidal waveform at a frequency corresponding to the round-trip time of the laser cavity. Each FBG forms a laser cavity independently in the FDML fiber laser because the light travels different length for each FBG. The very closely positioned two FBGs in a pair are operated simultaneously with a frequency in the FDML fiber laser. The spatial positions of the sensing pair can be distinguished from the variation of the applied frequency to the FFP-TF. One of the FBGs in the pair is used as a reference signal and the other one is fixed on the piezoelectric transducer stack to apply the dynamic strain. We successfully achieve real-time measurement of the abrupt change of the frequencies applied to the FBG without any signal processing delay. The real-time monitoring system is displayed simultaneously on the monitor for the variation of the two peaks, the modulation interval of the two peaks, and their fast Fourier transform spectrum. The frequency resolution of the dynamic variation could reach up to 0.5 Hz for 2 s integration time. It depends on the integration time to measure the dynamic variation. We believe that the real-time monitoring system will have a potential application for structural health monitoring.

Shock absorption ability of laminate mouth guards in two different malocclusions using fiber Bragg grating (FBG) sensor.

PubMed

Bhalla, Ashish; Grewal, Navneet; Tiwari, Umesh; Mishra, Vandana; Mehla, Nahar Singh; Raviprakash, Suryanarain; Kapur, Pawan

2013-06-01

The majority of orofacial injuries affect the upper jaw, with the maxillary incisors being most prone to injury, often accounting for as many as 80% of all cases. Children with malocclusion in the anterior segment of the maxilla are more prone to traumatic injuries than those exhibiting normal occlusion, because most often the damaging force impacts directly against the maxillary anterior teeth. Hence, because of the difference of dissipation of the impact force because of the presence or absence of malocclusion, the mouthguard's shock absorption capacity would be influenced by certain factors. In the present study, a unique in vitro experiment utilizing fiber Bragg Grating (FBG) as distributed strain sensors was carried out to evaluate the shock absorption ability of laminate customized mouthguards in two different malocclusions compared with normal occlusion. The impact was produced using a customized pendulum device with three interchangeable impact objects on typhodont models with two different malocclusions and normal occlusion from different heights. Response of gratings was monitored using an optical spectrum analyzer. Strain induced because each impact was determined from the Bragg's wavelength shifts for each grating. For every model, 12 impact strikes were measured using three different impact objects on the two specified sites by releasing the object from two different heights. The laminated mouthguards showed significant variation in shock absorption ability when different malocclusions were compared. Hence, modifications in the original design of the laminated mouthguards should be considered for athletic competitors with malocclusion to provide adequate protection against impact. FBG sensor has shown the unique advantage of high sensitivity to strain measurement and can be used in further studies. The height of the impact is an important variable in determining the shock absorption ability of mouthguards. © 2012 John Wiley & Sons A/S.

Dual line CW fiber laser module based on FBG combination

NASA Astrophysics Data System (ADS)

Dobashi, Kazuma; Hoshi, Masayuki; Hirohashi, Junji; Makio, Satoshi

2018-02-01

We developed the dual line fiber laser module based on FBG combination. The proposed configuration has several advantages such as compact, simple, and inexpensive. The laser was composed pump LD (40W), two HR FBGs for 1053 nm and 1058 nm, Yb-doped fiber, two OC FBGs for 1053 nm and 1058 nm, and delivery fiber. All single mode fibers were polarization maintained with approximately 6 micron core. All FBGs were mounted on holders with TECs and their temperatures were controlled independently. The center wavelengths of HR and OC FBGs were temperature dependent and their shifts are approximately 7 nm/degree-C for all integrated FBG. By adjusting the temperature, it is possible to realize the resonant condition for only 1053 nm or only for 1058 nm. Based on this configuration, we demonstrated dual line CW fiber laser module. This module was compact with the size of 200 mm X 150 mm X 23 mm. By adjusting the FBG temperatures, we obtained the output power of more than 10 W at 1053 nm and 1058 nm with linear polarization.

Environmental and reliability test of FBG based geophone as geophysical exploration instrument

NASA Astrophysics Data System (ADS)

Zhang, Xiaolei; Min, Li; Li, Ming; Jiang, Shaodong; Zhang, Faxiang; Sun, Zhihui; Ni, Jiasheng; Peng, Gangding; Wang, Chang

2017-10-01

A fiber Bragg grating (FBG) based geophone is designed for low-frequency signal detection has high acceleration response of about 60 dB re pm/g in a low frequency range of 5 Hz 60 Hz. To Guarantee normal operation in field test and practical application, an acceleration amplitude restriction is added in the mechanical design of the FBG geophone. Then a series of environmental and reliability test have been proceeded with online or offline monitoring of its working performance, including high and low temperature test, vibration test, shock test and free drop test. All the tests are planned according to National standard or Oil & Gas Industry Standard. And the experimental results indicate that our FBG geophone meet the criterion of oil and gas industry product and is capable of field application.

Dynamic optical arbitrary waveform generation with amplitude controlled by interference of two FBG arrays.

PubMed

Zhang, Ailing; Li, Changxiu

2012-10-08

In this paper, a novel structure of dynamic optical arbitrary waveform generation (O-AWG) with amplitude controlled by interference of two fiber Bragg grating (FBG) arrays is proposed. The FBG array consists of several FBGs and fiber stretchers (FSs). The amplitude is controlled by FSs through interference of two FBG arrays. The phase is controlled by FSs simultaneously. As a result, optical pulse trains with various waveforms as well as pulse trains with nonuniform pulse intensity, pulse spacing and pulse width in each period are obtained via FSs adjustment to change the phase shift of signal in each array.

Acoustic emission localization based on FBG sensing network and SVR algorithm

NASA Astrophysics Data System (ADS)

Sai, Yaozhang; Zhao, Xiuxia; Hou, Dianli; Jiang, Mingshun

2017-03-01

In practical application, carbon fiber reinforced plastics (CFRP) structures are easy to appear all sorts of invisible damages. So the damages should be timely located and detected for the safety of CFPR structures. In this paper, an acoustic emission (AE) localization system based on fiber Bragg grating (FBG) sensing network and support vector regression (SVR) is proposed for damage localization. AE signals, which are caused by damage, are acquired by high speed FBG interrogation. According to the Shannon wavelet transform, time differences between AE signals are extracted for localization algorithm based on SVR. According to the SVR model, the coordinate of AE source can be accurately predicted without wave velocity. The FBG system and localization algorithm are verified on a 500 mm×500 mm×2 mm CFRP plate. The experimental results show that the average error of localization system is 2.8 mm and the training time is 0.07 s.

Design and analysis of FBG based sensor for detection of damage in oil and gas pipelines for safety of marine life

NASA Astrophysics Data System (ADS)

Bedi, Amna; Kothari, Vaishali; Kumar, Santosh

2018-02-01

The under laid gas and oil pipelines on the seafloor are prone to various disturbances like seismic movements of the sea bed, oceanic currents, tsunamis. These factors tend to damage such pipelines connecting different locations of the world dependent on these pipelines for their day-to-day use of oil and natural gas. If damaged, the oil spills in the water bodies cause grave loss to marine life along with serious economic issues. It is not feasible to monitor the undersea pipelines manually because of the huge seafloor depth. For timely detection of such damage, a new technique using optical Fiber Bragg grating (FBG) sensors and its installation has been given in this work. The idea of an FBG sensor for detecting damage in pipeline structure based on the acoustic emission has been worked out. The numerical calculation has been done based on the fundamental of strain measurement and the output has been simulated using MATLAB.

Screening of Lactobacillus strains for their ability to produce conjugated linoleic acid in milk and to adhere to the intestinal tract.

PubMed

Sosa-Castañeda, J; Hernández-Mendoza, A; Astiazarán-García, H; Garcia, H S; Estrada-Montoya, M C; González-Córdova, A F; Vallejo-Cordoba, B

2015-10-01

Conjugated linoleic acid (CLA) has been shown to provide beneficial effects on health; however, the amount consumed in food is far from that required for the desired effects. Thus, increasing the CLA content in dairy foods through milk fermentation with specific lactic acid bacteria (LAB) offers an interesting alternative. Moreover, some LAB may be able to adhere to the intestinal mucosa and produce CLA through endogenous synthesis. Therefore, the objective of this study was to screen LAB isolates for their ability to produce CLA in skim milk and in simulated gastrointestinal conditions. Additionally, the ability of selected CLA-producing LAB to adhere to the intestinal mucosa in a murine model was assessed. Results showed that of 13 strains of Lactobacillus tested, only 4 were able to produce CLA in skim milk supplemented with linoleic acid (13.44 ± 0.78 to 50.9 ± 0.26 µg/mL). Furthermore, these 4 Lactobacillus strains were able to survive and produce CLA in simulated gastrointestinal conditions and to adhere to the intestinal mucosa of Wistar rats after 7 d of oral inoculation with fluorescently labeled bacteria. Accordingly, these 4 Lactobacillus strains may be used to manufacture fermented dairy foods to increase CLA content, and consumption of these fermented milks may result in CLA produced endogenously by these LAB. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

NASA Astrophysics Data System (ADS)

Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Aleksandrov, A.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M. M.; De Lentdecker, G.; De Oliveira, R.; de Robertis, G.; Dildick, S.; Dorney, B.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferrini, M.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lalli, A.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passamonti, L.; Passeggio, G.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Primavera, F.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Russo, A.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Valente, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

2018-02-01

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.

Strain sensors for high field pulse magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Christian; Zheng, Yan; Easton, Daniel

2009-01-01

In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Threemore » operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.« less

Fiber sensor network with multipoint sensing using double-pass hybrid LPFG-FBG sensor configuration

NASA Astrophysics Data System (ADS)

Yong, Yun-Thung; Lee, Sheng-Chyan; Rahman, Faidz Abd

2017-03-01

This is a study on double-pass intensity-based hybrid Long Period Fiber Grating (LPFG)and Fiber Bragg Grating (FBG) sensor configuration where a fiber sensor network was constructed with multiple sensing capability. The sensing principle is based on interrogation of intensity changes of the reflected signal from an FBG caused by the LPFG spectral response to the surrounding perturbations. The sensor network developed was tested in monitoring diesel adulteration of up to a distance of 8 km. Kerosene concentration from 0% to 50% was added as adulterant into diesel. The sensitivity of the double-pass hybrid LPFG-FBG sensor over multiple points was>0.21 dB/% (for adulteration range of 0-30%) and >0.45 dB/% from 30% to 50% adulteration. It is found that the sensitivity can drop up to 35% when the fiber length increased from 0 km to 8 km (for the case of adulteration of 0-30%). With the multiple sensing capabilities, normalized FBG's reflected power can be demodulated at the same time for comparison of sensitivity performance across various fiber sensors.

Monitoring of fatigue damage in composite lap-joints using guided waves and FBG sensors

NASA Astrophysics Data System (ADS)

Karpenko, Oleksii; Khomenko, Anton; Koricho, Ermias; Haq, Mahmoodul; Udpa, Lalita

2016-02-01

Adhesive bonding is being increasingly employed in many applications as it offers possibility of light-weighting and efficient multi-material joining along with reduction in time and cost of manufacturing. However, failure initiation and progression in critical components like joints, specifically in fatigue loading is not well understood, which necessitates reliable NDE and SHM techniques to ensure structural integrity. In this work, concurrent guided wave (GW) and fiber Bragg grating (FBG) sensor measurements were used to monitor fatigue damage in adhesively bonded composite lap-joints. In the present set-up, one FBG sensor was strategically embedded in the adhesive bond-line of a lap-joint, while two other FBGs were bonded on the surface of the adherends. Full spectral responses of FBG sensors were collected and compared at specific intervals of fatigue loading. In parallel, guided waves were actuated and sensed using PZT wafers mounted on the composite adherends. Experimental results demonstrated that time-of-flight (ToF) of the fundamental modes transmitted through the bond-line and spectral response of FBG sensors were sensitive to fatigue loading and damage. Combination of guided wave and FBG measurements provided the desired redundancy and synergy in the data to evaluate the degradation in bond-line properties. Measurements taken in the presence of continuously applied load replicated the in-situ/service conditions. The approach shows promise in understanding the behavior of bonded joints subjected to complex loading.

An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings

PubMed Central

Zhang, Xiaodong; Hou, Chenggang

2017-01-01

The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs) is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes. PMID:29258164

An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings.

PubMed

Niu, Hang; Zhang, Xiaodong; Hou, Chenggang

2017-12-16

The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs) is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes.

Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²⁺-doped optical fiber.

PubMed

Liu, Zhengyong; Tse, Ming-Leung Vincent; Zhang, A Ping; Tam, Hwa-Yaw

2014-10-15

A novel microfluidic flowmeter integrated with microfiber Bragg grating (µFBG) is presented. Two glass capillaries and a short length of high-light-absorption Co²⁺-doped optical fiber were stacked inside a larger outer capillary tube. The stack was then drawn into a tapered device. Two microchannels with the diameter of ~50  μm were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²⁺-doped fiber with waist diameter of ~70  μm, and acts as a flow-rate sensor. A pump laser with wavelength of 1480 nm was utilized to locally heat the µFBG, rendering the µFBG as miniature "hot-wire" flowmeter. The flow rate of the liquid in the microchannels is determined by the induced wavelength shift of the µFBG. The experimental results achieve a minimum detectable change of ~16  nL/s in flow rate, which is very promising in the use as part of biochips.

Non-contact FBG sensing based steam turbine rotor dynamic balance vibration detection system

NASA Astrophysics Data System (ADS)

Li, Tianliang; Tan, Yuegang; Cai, Lin

2015-10-01

This paper has proposed a non-contact vibration sensor based on fiber Bragg grating sensing, and applied to detect vibration of steam turbine rotor dynamic balance experimental platform. The principle of the sensor has been introduced, as well as the experimental analysis; performance of non-contact FBG vibration sensor has been analyzed in the experiment; in addition, turbine rotor dynamic vibration detection system based on eddy current displacement sensor and non-contact FBG vibration sensor have built; finally, compared with results of signals under analysis of the time domain and frequency domain. The analysis of experimental data contrast shows that: the vibration signal analysis of non-contact FBG vibration sensor is basically the same as the result of eddy current displacement sensor; it verified that the sensor can be used for non-contact measurement of steam turbine rotor dynamic balance vibration.

Study of the technics of coating stripping and FBG writing on polyimide fiber

NASA Astrophysics Data System (ADS)

Song, ZhiQiang; Qi, HaiFeng; Ni, JiaSheng; Wang, Chang

2017-10-01

Compared with ordinary optical fiber, polyimide fiber has the characteristics of high temperature resistance and high strength, which has important application in the field of optical fiber sensing. The common methods of polyimide coating stripping were introduced in this paper, including high temperature stripping, chemical stripping and arc ablation. In order to meet the requirements of FBG writing technology, a method using argon ion laser ablation coating was proposed. The method can precisely control the stripping length of the coating and completely does not affect the tensile strength of the optical fiber. According to the experiment, the fabrication process of polyimide FBG is stripping-hydrogen loadingwriting. Under the same conditions, 10 FBG samples were fabricated with good uniformity of wavelength bandwidth and reflectivity. UV laser ablation of polyimide coating has been proved to be a safe, reliable and efficient method.

Structured FBG filters for 10-Gb/s DPSK signal demodulation in single ended applications

NASA Astrophysics Data System (ADS)

Marazzi, L.; Boffi, P.; Parolari, P.; Martinelli, M.; Gatti, D.; Coluccelli, N.; Longhi, S.

2011-05-01

Differential phase-shift keying (DPSK) demodulations operated by a structured fiber Bragg grating (FBG) filter and by a Mach-Zehnder delay interferometer (MZDI) in a single-ended configuration are compared. Experimental measurements at 10 Gb/s demonstrate that a specially designed FBG outperforms an integrated-optic MZDI of ˜4 dB and ˜3.5 dB in back-to-back and after 25-km propagation, respectively. Both demodulators show low polarization sensitivity and signal frequency detuning dependence, but only MZDI operating point requires a thermal control. FBG filter proves an interesting solution for DPSK demodulation in low-cost applications and, moreover, can be designed to match colorless requirements of wave division multiplexed passive optical network (WDM-PON) applications.

Time-delay signature of chaos in 1550 nm VCSELs with variable-polarization FBG feedback.

PubMed

Li, Yan; Wu, Zheng-Mao; Zhong, Zhu-Qiang; Yang, Xian-Jie; Mao, Song; Xia, Guang-Qiong

2014-08-11

Based on the framework of spin-flip model (SFM), the output characteristics of a 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject to variable-polarization fiber Bragg grating (FBG) feedback (VPFBGF) have been investigated. With the aid of the self-correlation function (SF) and the permutation entropy (PE) function, the time-delay signature (TDS) of chaos in the VPFBGF-VCSEL is evaluated, and then the influences of the operation parameters on the TDS of chaos are analyzed. The results show that the TDS of chaos can be suppressed efficiently through selecting suitable coupling coefficient and feedback rate of the FBG, and is weaker than that of chaos generated by traditional variable-polarization mirror feedback VCSELs (VPMF-VCSELs) or polarization-preserved FBG feedback VCSELs (PPFBGF-VCSELs).

Effects of the inclined femto laser incidence at the phase mask on FBG carving

NASA Astrophysics Data System (ADS)

Wang, Jian; Wu, Shengli; Zhang, Jintao; Ren, Wenyi

2015-12-01

The inclined incidence of the femto laser on the phase mask in fiber Bragg grating (FBG) carving has a significant effect on the quality of FBG fabrication. Based on that the infrared femto laser has highly spatial coherence and the order walk-off will happen behind the phase mask, the interferogram generated at the fiber core by the inclined femto laser beam has been analyzed using the multi-beam interference principle. The influence of beam inclination on the coherence of the 0th and ± 1st orders diffraction with different exposure distance, the visibility of interferogram and the frequency component of the transverse interferogram intensity has also been analyzed. It is meaningful for the FBG fabricating with the femto laser.

Simultaneous Strain and Temperature Measurement Using a Single Fiber Bragg Grating Coated with a Thermochromic Material

DTIC Science & Technology

2017-03-27

7 The objective is to demonstrate simultaneous strain and temperature measurement using a single Fiber Bragg Grating (FBG). We developed two...huang@uta.edu Contract Information Contract Number: N00014-14-1-0636 Contract Title: : Simultaneous Strain and Temperature Measurement Using a...University of Texas Arlington Abstract: the objective of this project is to demonstrate simultaneous strain and temperature measurement using a single

High strain FBG sensors for structural fatigue testing of military aircraft

NASA Astrophysics Data System (ADS)

Tejedor, S.; Kopczyk, J.; Nuyens, T.; Davis, C.

2012-02-01

This paper reports on a series of tests investigating the performance of Draw Tower Gratings (DTGs) combined with custom-designed broad area packaging and bonding techniques for high-strain sensing applications on Defence platforms. The sensors and packaging were subjected to a series of high-strain static and cyclic loading tests and a summary of these results is presented.

Adherence of bacteria to mucus collected from different parts of the reproductive tract of heifers and cows.

PubMed

Styková, E; Nemcová, R; Valocký, I; Novotný, F; Guba, P

2013-11-01

In the present study, we examined the adherence of indigenous vaginal bacteria, probiotic strains, and metritis pathogens to mucus collected from different parts of the reproductive tracts of heifers and cows and compared their adherence with the bacterial adherence to mucus collected from the stomach and large intestine of pigs. Most of the vaginal strains adhered to mucus collected from different parts of the reproductive tract and strongly adhered to gastric mucus, with the exception of Lactobacillus buchneri 24S8. Only Lactobacillus mucosae 29S8, Enterococcus faecium E21, and E. faecium EAC adhered to colonic mucus. Probiotic strains adhered strongly to mucus collected from the reproductive tract and gastric mucus but did not adhere to colonic mucus. Pathogenic strains were adherent to vaginal, uterine horn, and gastric mucus, except Escherichia coli O8:K88ab:H9 (65), Fusobacterium necrophorum, and Gardnerella vaginalis, which adhered to uterine cervix mucus. Only Kocuria kristinae and G. vaginalis adhered to uterine body mucus; E. coli O149:K88ac (EC) adhered to colonic mucus. The strains did not exhibit host specificity but rather strain specificity. The ability to adhere to mucus was a characteristic unique to each strain. To our knowledge, this is the first report regarding in vitro adherence of GRAS (Generally Regarded As Safe) lactobacilli isolated from different sources to mucus collected from different parts of the reproductive tract.

Adherence of Aeromonas hydrophila strains to human enterocyte-like cells pre-infected with rotavirus.

PubMed

Bertuccio, M P; Picerno, I; Scoglio, M E

2012-09-01

The interest grown in these years about emerging pathogens in the onset of intestinal disease showed that the pathogenic mechanism is a multifactorial event. Our objective was to evaluate the role of co-infection with rotavirus in the expression of Aeromonas spp adhesiveness. The rate of co-infection involves contact of Caco-2 cells with the virus, followed by adsorption for 1 and 2 hours. Aliquots of bacterial suspensions were added to tissue-culture plates. After infection, cell monolayers were lysed; serially diluted lysates were plated to determine the number of bound bacteria by performing colony forming units (CFU) counts. Non-adhesive strains were not subject to variations resulting from co-infection, while those who had medium or high adhesiveness gave rise to an increase of the same. Infection with rotavirus promotes the Aeromonas ability to adhere to Caco-2 cells and this effect depends on the duration of infection and on the starting adhesiveness of bacteria strain.

Medium-high frequency FBG accelerometer with integrative matrix structure.

PubMed

Dai, Yutang; Yin, Guanglin; Liu, Bin; Xu, Gang; Karanja, Joseph Muna

2015-04-10

To meet the requirements for medium-high frequency vibration monitoring, a new type fiber Bragg grating (FBG) accelerometer with an integrative matrix structure is proposed. Two symmetrical flexible gemels are used as elastic elements, which drive respective inertial mass moving reversely when exciting vibration exists, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, by which the influence of the structural parameters on the sensitivity and eigenfrequency is discussed. Sensitivity higher than 200  pm/g and an eigenfrequency larger than 3000 Hz can be realized separately, but both cannot be achieved simultaneously. Aiming for a broader measuring frequency range, a prototype accelerometer with an eigenfrequency near 3000 Hz is designed, and results from a shake table test are also demonstrated.

Analysis on the impact of FBG reflectance spectrum with different optical fiber connection in vacuum thermal environment

NASA Astrophysics Data System (ADS)

Zhang, Jingchuan; Zhang, Wen; Lv, Jianfeng; Liang, Shuo; Wang, Lei; Li, Xiyuan

2018-01-01

To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, FBG on sleeve compactly single model fiber with two typical different kind of connection such as fiber splicing and optical fiber connector are researched. Influence of the different connection to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, experimental program of influence on FBG reflection spectrum characteristics is designed. Then, a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG with two typical different connections under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different single-mode optical fiber connection dropped to -196 °C from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 °C temperature cycle).

Dynamic Method of Neutral Axis Position Determination and Damage Identification with Distributed Long-Gauge FBG Sensors

PubMed Central

Tang, Yongsheng; Ren, Zhongdao

2017-01-01

The neutral axis position (NAP) is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of flexural structures can be facilitated. PMID:28230747

Dynamic Method of Neutral Axis Position Determination and Damage Identification with Distributed Long-Gauge FBG Sensors.

PubMed

Tang, Yongsheng; Ren, Zhongdao

2017-02-20

The neutral axis position (NAP) is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of flexural structures can be facilitated.

Pathophysiological condition changes the conformation of a flexible FBG-related protein, switching it from pathogen-recognition to host-interaction.

PubMed

Zhang, Jing; Yang, Lifeng; Anand, Ganesh Srinivasan; Ho, Bow; Ding, Jeak Ling

2011-10-01

Although homeostatic disturbance of the blood pH and calcium in the vicinity of tissue injury/malignancy/local infection seems subtle, it can cause substantial pathophysiological consequences, a phenomenon which has remained largely unexplored. The fibrinogen-related proteins (FREPs) containing fibrinogen-like domain (FBG) represent a conserved protein family with a common calcium-binding region, implying the presence of elements responsive to physiological perturbation. Here, we studied the molecular interaction between a representative FREP, the M-ficolin, and an acute phase blood protein, the C-reactive protein (CRP), both of which are known to trigger and control seminal pathways in infection and injury. Using hydrogen-deuterium exchange mass spectrometry, we showed that the C-terminal region of M-ficolin FBG underwent dramatic conformational change upon pH and calcium perturbations. Biochemical and biophysical assays showed that under defined pathophysiological condition (pH 6.5, 2.0 mM calcium), the FBG:CRP interaction occurred more strongly compared to that under physiological condition (pH 7.4, 2.5 mM calcium). We identified the binding interface between CRP and FBG, locating it to the pH- and calcium-sensitive C-terminal region of FBG. By site-directed mutagenesis, we determined H284 in the N-acetylglucosamine (GlcNAc)-binding pocket of the FBG, to be the critical CRP-binding residue. This conformational switch involving H284, explains how the pathophysiologically-driven FBG:CRP interaction diverts the M-ficolin away from GlcNAc/pathogen-recognition to host protein-protein interaction, thus enabling the host to regain homeostatic control. Our elucidation of the binding interface at the flexible FBG domain provides insights into the bioactive centre of the M-ficolin, and possibly other FREPs, which might aid future development of immunomodulators. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Polarization-resolved time-delay signatures of chaos induced by FBG-feedback in VCSEL.

PubMed

Zhong, Zhu-Qiang; Li, Song-Sui; Chan, Sze-Chun; Xia, Guang-Qiong; Wu, Zheng-Mao

2015-06-15

Polarization-resolved chaotic emission intensities from a vertical-cavity surface-emitting laser (VCSEL) subject to feedback from a fiber Bragg grating (FBG) are numerically investigated. Time-delay (TD) signatures of the feedback are examined through various means including self-correlations of intensity time-series of individual polarizations, cross-correlation of intensities time-series between both polarizations, and permutation entropies calculated for the individual polarizations. The results show that the TD signatures can be clearly suppressed by selecting suitable operation parameters such as the feedback strength, FBG bandwidth, and Bragg frequency. Also, in the operational parameter space, numerical maps of TD signatures and effective bandwidths are obtained, which show regions of chaotic signals with both wide bandwidths and weak TD signatures. Finally, by comparing with a VCSEL subject to feedback from a mirror, the VCSEL subject to feedback from the FBG generally shows better concealment of the TD signatures with similar, or even wider, bandwidths.

Verification of Non-Invasive Blood Glucose Measurement Method Based on Pulse Wave Signal Detected by FBG Sensor System.

PubMed

Kurasawa, Shintaro; Koyama, Shouhei; Ishizawa, Hiroaki; Fujimoto, Keisaku; Chino, Shun

2017-11-23

This paper describes and verifies a non-invasive blood glucose measurement method using a fiber Bragg grating (FBG) sensor system. The FBG sensor is installed on the radial artery, and the strain (pulse wave) that is propagated from the heartbeat is measured. The measured pulse wave signal was used as a collection of feature vectors for multivariate analysis aiming to determine the blood glucose level. The time axis of the pulse wave signal was normalized by two signal processing methods: the shortest-time-cut process and 1-s-normalization process. The measurement accuracy of the calculated blood glucose level was compared with the accuracy of these signal processing methods. It was impossible to calculate a blood glucose level exceeding 200 mg/dL in the calibration curve that was constructed by the shortest-time-cut process. In the 1-s-normalization process, the measurement accuracy of the blood glucose level was improved, and a blood glucose level exceeding 200 mg/dL could be calculated. By verifying the loading vector of each calibration curve to calculate the blood glucose level with a high measurement accuracy, we found the gradient of the peak of the pulse wave at the acceleration plethysmogram greatly affected.

Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference.

PubMed

Park, Hyoung-Jun; Song, Minho

2008-10-29

The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method.

Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference

PubMed Central

Park, Hyoung-Jun; Song, Minho

2008-01-01

The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method. PMID:27873898

Optical sensor based on hybrid FBG/titanium dioxide coated LPFG for monitoring organic solvents in edible oils.

PubMed

Coelho, Luís; Viegas, Diana; Santos, José Luís; de Almeida, José Manuel Marques Martins

2016-01-01

A hybrid optical sensing scheme based on a fiber Bragg grating (FBG) combined with a titanium dioxide coated long period fiber grating (LPFG) for monitoring organic solvents in high refractive index edible oils is reported. In order to investigate and optimize the sensor performance, two different FBG/LPFG interrogation systems were investigated. The readout of the sensor was implemented using either the wavelength shift of the LPFG resonance dip or the variation in the optical power level of the reflected/transmitted light at the FBG wavelength peak, which in turn depends on the wavelength position of the LPFG resonance. Hexane concentrations up to 20%V/V, corresponding to the refractive index range from 1.451 to 1.467, were considered. For the transmission mode of operation, sensitivities of 1.41 nm/%V/V and 0.11 dB/%V/V, with resolutions of 0.58%V/V and 0.29%V/V, were achieved when using the LPFG wavelength shift and the FBG transmitted optical power, respectively. For the FBG reflection mode of operation, a sensitivity of 0.07 dB/%V/V and a resolution better than 0.16%V/V were estimated. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of optical FBG force measurement system for the medical application

NASA Astrophysics Data System (ADS)

Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

2010-03-01

Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

Development of optical FBG force measurement system for the medical application

NASA Astrophysics Data System (ADS)

Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

2009-12-01

Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

Fiber Bragg Gratings, IT Techniques and Strain Gauge Validation for Strain Calculation on Aged Metal Specimens

PubMed Central

Montero, Ander; de Ocariz, Idurre Saez; Lopez, Ion; Venegas, Pablo; Gomez, Javier; Zubia, Joseba

2011-01-01

This paper studies the feasibility of calculating strains in aged F114 steel specimens with Fiber Bragg Grating (FBG) sensors and infrared thermography (IT) techniques. Two specimens have been conditioned under extreme temperature and relative humidity conditions making comparative tests of stress before and after aging using different adhesives. Moreover, a comparison has been made with IT techniques and conventional methods for calculating stresses in F114 steel. Implementation of Structural Health Monitoring techniques on real aircraft during their life cycle requires a study of the behaviour of FBG sensors and their wiring under real conditions, before using them for a long time. To simulate aging, specimens were stored in a climate chamber at 70 °C and 90% RH for 60 days. This study is framed within the Structural Health Monitoring (SHM) and Non Destructuve Evaluation (NDE) research lines, integrated into the avionics area maintained by the Aeronautical Technologies Centre (CTA) and the University of the Basque Country (UPV/EHU). PMID:22346619

Improving frequencies range measurement of vibration sensor based on Fiber Bragg Grating (FBG)

NASA Astrophysics Data System (ADS)

Qomaruddin; Setiono, A.; Afandi, M. I.

2017-04-01

This research aimed to develop a vibration sensor based on Fiber Bragg Grating (FBG). The design was mainly done by attaching FBG at the cantilever. The free-end of the cantilever was tied to a vibration source in order to increase the measurement range of vibration frequencies. The results indicated that the developed sensor was capable of detecting wide range of frequencies (i.e. 10 - 1700 Hz). The results also showed both good stability and repeatability. The measured frequency range was 566 times greater than the range obtained from the previous works.

Development of an FBG Sensor Array for Multi-Impact Source Localization on CFRP Structures.

PubMed

Jiang, Mingshun; Sai, Yaozhang; Geng, Xiangyi; Sui, Qingmei; Liu, Xiaohui; Jia, Lei

2016-10-24

We proposed and studied an impact detection system based on a fiber Bragg grating (FBG) sensor array and multiple signal classification (MUSIC) algorithm to determine the location and the number of low velocity impacts on a carbon fiber-reinforced polymer (CFRP) plate. A FBG linear array, consisting of seven FBG sensors, was used for detecting the ultrasonic signals from impacts. The edge-filter method was employed for signal demodulation. Shannon wavelet transform was used to extract narrow band signals from the impacts. The Gerschgorin disc theorem was used for estimating the number of impacts. We used the MUSIC algorithm to obtain the coordinates of multi-impacts. The impact detection system was tested on a 500 mm × 500 mm × 1.5 mm CFRP plate. The results show that the maximum error and average error of the multi-impacts' localization are 9.2 mm and 7.4 mm, respectively.

Photothermal effects in phase shifted FBG with varied light wavelength and intensity.

PubMed

Ding, Meng; Chen, Dijun; Fang, Zujie; Wang, Di; Zhang, Xi; Wei, Fang; Yang, Fei; Ying, Kang; Cai, Haiwen

2016-10-31

The intensity enhancement effect of a phase-shifted fiber Bragg grating (PSFBG) is investigated theoretically and experimentally in this paper. Due to the effect, both of the FBG reflection bands and the transmission peak show red-shift with the increase of pump light wavelength from the shorter side to the longer side of the Bragg wavelength. The transmission peak shifts in pace with the pump's wavelength, which is much faster than the reflection band. The maximum shift increases with the pump power. In contrast, the red-shift is very small when the pump light deceases from the longer side of the Bragg wavelength. Such asymmetric behavior is checked dynamically by using a frequency modulated laser in a serrated wave, showing push-pull behavior. The effect of the characteristics of thermal dissipation conditions is also measured. The fiber loss coefficient of FBG being tested is estimated from the measured data to be about 0.001 mm^-1, which may be attributed to the H₂-loading and UV exposure in FBG fabrication. The observed phenomena are believed of importance in application where PSFBG is utilized as a narrow linewidth filter.

Use of Fiber Bragg Grating (FBG) sensors for performing automated bridge pier structural damage detection and scour monitoring.

DOT National Transportation Integrated Search

2012-04-01

The goal of this study was to evaluate the performance of Fiber Bragg Grating (FBG) sensors able to detect impacts with : different frequencies on a bridge pier. The FBG technology was evaluated under controlled conditions in a laboratory : flume set...

Performance Optimization Design for a High-Speed Weak FBG Interrogation System Based on DFB Laser.

PubMed

Yao, Yiqiang; Li, Zhengying; Wang, Yiming; Liu, Siqi; Dai, Yutang; Gong, Jianmin; Wang, Lixin

2017-06-22

A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve the multiplexing capacity, a waveform repairing algorithm is designed to extend the dynamic demodulation range of FBG sensors. It is based on the fact that the spectrum of an FBG keeps stable over a long period of time. Compared with the pre-collected spectra, the distorted spectra waveform are identified and repaired. Experimental results show that all the identical weak FBGs are distinguished and demodulated at the speed of 100 kHz with a linearity of above 0.99, and the range of dynamic demodulation is extended by 40%.

Performance Optimization Design for a High-Speed Weak FBG Interrogation System Based on DFB Laser

PubMed Central

Yao, Yiqiang; Li, Zhengying; Wang, Yiming; Liu, Siqi; Dai, Yutang; Gong, Jianmin; Wang, Lixin

2017-01-01

A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve the multiplexing capacity, a waveform repairing algorithm is designed to extend the dynamic demodulation range of FBG sensors. It is based on the fact that the spectrum of an FBG keeps stable over a long period of time. Compared with the pre-collected spectra, the distorted spectra waveform are identified and repaired. Experimental results show that all the identical weak FBGs are distinguished and demodulated at the speed of 100 kHz with a linearity of above 0.99, and the range of dynamic demodulation is extended by 40%. PMID:28640187

In-situ monitoring of curing and ageing effects in FRP plates using embedded FBG sensors

NASA Astrophysics Data System (ADS)

Xian, Guijun; Wang, Chuan; Li, Hui

2010-04-01

In recent years, fiber reinforced polymer (FRP) composites have been widely applied in civil engineering for retrofitting or renewal of existing structures. Since FRP composite may degrade when exposed to severe outdoor environments, a serious concern has been raised on its long term durability. In the present study, fiber Bragg grating (FBG) sensors were embedded in glass-, carbon- and basalt-fiber reinforced epoxy based FRP plates with wet lay-up technology, to in-situ monitor the stain changes in FRPs during the curing, and water immersion and freeze-thaw ageing processes. The study demonstrates that the curing of epoxy resin brings in a slight tension strain (e.g., 10 ~ 30 μɛ) along the fiber direction and a high contraction (e.g., ~ 1100μɛ) in the direction perpendicular to the fibers, mainly due to the resin shrinkage. The cured FRP strips were then subjected to distilled water immersion at 80oC and freeze-thaw cycles from -30°C to 30°C. Remarkable strain changes of FRPs due to the variation of the temperatures during freeze-thaw cycles indicate the potential property degradation from fatigue. The maximum strain change is dependent on the fiber types and directions to the fiber. Based on the monitored strain values with temperature change and water uptake content, CTE (coefficient of thermal expansion) and CME (coefficient of moisture expansion) are exactly determined for the FRPs.

Multiepitope fusion antigen induces broadly protective antibodies that prevent adherence of Escherichia coli strains expressing colonization factor antigen I (CFA/I), CFA/II, and CFA/IV.

PubMed

Ruan, Xiaosai; Knudsen, David E; Wollenberg, Katie M; Sack, David A; Zhang, Weiping

2014-02-01

Diarrhea is the second leading cause of death in children younger than 5 years and continues to be a major threat to global health. Enterotoxigenic Escherichia coli (ETEC) strains are the most common bacteria causing diarrhea in developing countries. ETEC strains are able to attach to host small intestinal epithelial cells by using bacterial colonization factor antigen (CFA) adhesins. This attachment helps to initiate the diarrheal disease. Vaccines that induce antiadhesin immunity to block adherence of ETEC strains that express immunologically heterogeneous CFA adhesins are expected to protect against ETEC diarrhea. In this study, we created a CFA multiepitope fusion antigen (MEFA) carrying representative epitopes of CFA/I, CFA/II (CS1, CS2, and CS3), and CFA/IV (CS4, CS5, and CS6), examined its immunogenicity in mice, and assessed the potential of this MEFA as an antiadhesin vaccine against ETEC. Mice intraperitoneally immunized with this CFA MEFA exhibited no adverse effects and developed immune responses to CFA/I, CFA/II, and CFA/IV adhesins. Moreover, after incubation with serum of the immunized mice, ETEC or E. coli strains expressing CFA/I, CFA/II, or CFA/IV adhesins were significantly inhibited in adherence to Caco-2 cells. Our results indicated this CFA MEFA elicited antibodies that not only cross-reacted to CFA/I, CFA/II and CFA/IV adhesins but also broadly inhibited adherence of E. coli strains expressing these seven adhesins and suggested that this CFA MEFA could be a candidate to induce broad-spectrum antiadhesin protection against ETEC diarrhea. Additionally, this antigen construction approach (creating an MEFA) may be generally used in vaccine development against heterogenic pathogens.

In-vivo determination of chewing patterns using FBG and artificial neural networks

NASA Astrophysics Data System (ADS)

Pegorini, Vinicius; Zen Karam, Leandro; Rocha Pitta, Christiano S.; Ribeiro, Richardson; Simioni Assmann, Tangriani; Cardozo da Silva, Jean Carlos; Bertotti, Fábio L.; Kalinowski, Hypolito J.; Cardoso, Rafael

2015-09-01

This paper reports the process of pattern classification of the chewing process of ruminants. We propose a simplified signal processing scheme for optical fiber Bragg grating (FBG) sensors based on machine learning techniques. The FBG sensors measure the biomechanical forces during jaw movements and an artificial neural network is responsible for the classification of the associated chewing pattern. In this study, three patterns associated to dietary supplement, hay and ryegrass were considered. Additionally, two other important events for ingestive behavior studies were monitored, rumination and idle period. Experimental results show that the proposed approach for pattern classification has been capable of differentiating the materials involved in the chewing process with a small classification error.

Influence of Individual Differences on the Calculation Method for FBG-Type Blood Pressure Sensors

PubMed Central

Koyama, Shouhei; Ishizawa, Hiroaki; Fujimoto, Keisaku; Chino, Shun; Kobayashi, Yuka

2016-01-01

In this paper, we propose a blood pressure calculation and associated measurement method that by using a fiber Bragg grating (FBG) sensor. There are several points at which the pulse can be measured on the surface of the human body, and when a FBG sensor located at any of these points, the pulse wave signal can be measured. The measured waveform is similar to the acceleration pulse wave. The pulse wave signal changes depending on several factors, including whether or not the individual is healthy and/or elderly. The measured pulse wave signal can be used to calculate the blood pressure using a calibration curve, which is constructed by a partial least squares (PLS) regression analysis using a reference blood pressure and the pulse wave signal. In this paper, we focus on the influence of individual differences from calculated blood pressure based on each calibration curve. In our study, the calculated blood pressure from both the individual and overall calibration curves were compared, and our results show that the calculated blood pressure based on the overall calibration curve had a lower measurement accuracy than that based on an individual calibration curve. We also found that the influence of the individual differences on the calculated blood pressure when using the FBG sensor method were very low. Therefore, the FBG sensor method that we developed for measuring the blood pressure was found to be suitable for use by many people. PMID:28036015

Influence of Individual Differences on the Calculation Method for FBG-Type Blood Pressure Sensors.

PubMed

Koyama, Shouhei; Ishizawa, Hiroaki; Fujimoto, Keisaku; Chino, Shun; Kobayashi, Yuka

2016-12-28

In this paper, we propose a blood pressure calculation and associated measurement method that by using a fiber Bragg grating (FBG) sensor. There are several points at which the pulse can be measured on the surface of the human body, and when a FBG sensor located at any of these points, the pulse wave signal can be measured. The measured waveform is similar to the acceleration pulse wave. The pulse wave signal changes depending on several factors, including whether or not the individual is healthy and/or elderly. The measured pulse wave signal can be used to calculate the blood pressure using a calibration curve, which is constructed by a partial least squares (PLS) regression analysis using a reference blood pressure and the pulse wave signal. In this paper, we focus on the influence of individual differences from calculated blood pressure based on each calibration curve. In our study, the calculated blood pressure from both the individual and overall calibration curves were compared, and our results show that the calculated blood pressure based on the overall calibration curve had a lower measurement accuracy than that based on an individual calibration curve. We also found that the influence of the individual differences on the calculated blood pressure when using the FBG sensor method were very low. Therefore, the FBG sensor method that we developed for measuring the blood pressure was found to be suitable for use by many people.

Production of a mouse strain with impaired glucose tolerance by systemic heterozygous knockout of the glucokinase gene and its feasibility as a prediabetes model

PubMed Central

SAITO, Mikako; KANEDA, Asako; SUGIYAMA, Tae; IIDA, Ryousuke; OTOKUNI, Keiko; KABURAGI, Misako; MATSUOKA, Hideaki

2015-01-01

Exon II of glucokinase (Gk) was deleted to produce a systemic heterozygous Gk knockout (Gk+/−) mouse. The relative expression levels of Gk in the heart, lung, liver, stomach, and pancreas in Gk+/− mice ranged from 0.41–0.68 versus that in wild (Gk+/+) mice. On the other hand, its expression levels in the brain, adipose tissue, and muscle ranged from 0.95–1.03, and its expression levels in the spleen and kidney were nearly zero. Gk knockout caused no remarkable off-target effect on the expression of 7 diabetes causing genes (Shp, Hnf1a, Hnf1b, Irs1, Irs2, Kir6.2, and Pdx1) in 10 organs. The glucose tolerance test was conducted to determine the blood glucose concentrations just after fasting for 24 h (FBG) and at 2 h after high-glucose application (GTT2h). The FBG-GTT2h plots obtained with the wild strain fed the control diet (CD), Gk+/− strain fed the CD, and Gk+/− strain fed the HFD were distributed in separate areas in the FBG-GTT2h diagram. The respective areas could be defined as the normal state, prediabetes state, and diabetes state, respectively. Based on the results, the criteria for prediabetes could be defined for the Gk+/− strain developed in this study. PMID:25765873

Design and performance investigation of a highly accurate apodized fiber Bragg grating-based strain sensor in single and quasi-distributed systems.

PubMed

Ali, Taha A; Shehata, Mohamed I; Mohamed, Nazmi A

2015-06-01

In this work, fiber Bragg grating (FBG) strain sensors in single and quasi-distributed systems are investigated, seeking high-accuracy measurement. Since FBG-based strain sensors of small lengths are preferred in medical applications, and that causes the full width at half-maximum (FWHM) to be larger, a new apodization profile is introduced for the first time, to the best of our knowledge, with a remarkable FWHM at small sensor lengths compared to the Gaussian and Nuttall profiles, in addition to a higher mainlobe slope at these lengths. A careful selection of apodization profiles with detailed investigation is performed-using sidelobe analysis and the FWHM, which are primary judgment factors especially in a quasi-distributed configuration. A comparison between the elite selection of apodization profiles (extracted from related literature) and the proposed new profile is carried out covering the reflectivity peak, FWHM, and sidelobe analysis. The optimization process concludes that the proposed new profile with a chosen small length (L) of 10 mm and Δn_ac of 1.4×10^-4 is the optimum choice for single stage and quasi-distributed strain-sensor networks, even better than the Gaussian profile at small sensor lengths. The proposed profile achieves the smallest FWHM of 15 GHz (suitable for UDWDM), and the highest mainlobe slope of 130 dB/nm. For the quasi-distributed scenario, a noteworthy high isolation of 6.953 dB is achieved while applying a high strain value of 1500 μstrain (με) for a five-stage strain-sensing network. Further investigation was undertaken, proving that consistency in choosing the apodization profile in the quasi-distributed network is mandatory. A test was made of the inclusion of a uniform apodized sensor among other apodized sensors with the proposed profile in an FBG strain-sensor network.

Enhanced adherence of methicillin-resistant Staphylococcus pseudintermedius sequence type 71 to canine and human corneocytes

PubMed Central

2014-01-01

The recent worldwide spread of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in dogs is a reason for concern due to the typical multidrug resistance patterns displayed by some MRSP lineages such as sequence type (ST) 71. The objective of this study was to compare the in vitro adherence properties between MRSP and methicillin-susceptible (MSSP) strains. Four MRSP, including a human and a canine strain belonging to ST71 and two canine non-ST71 strains, and three genetically unrelated MSSP were tested on corneocytes collected from five dogs and six humans. All strains were fully characterized with respect to genetic background and cell wall-anchored protein (CWAP) gene content. Seventy-seven strain-corneocyte combinations were tested using both exponential- and stationary-phase cultures. Negative binomial regression analysis of counts of bacterial cells adhering to corneocytes revealed that adherence was significantly influenced by host and strain genotype regardless of bacterial growth phase. The two MRSP ST71 strains showed greater adherence than MRSP non-ST71 (p < 0.0001) and MSSP (p < 0.0001). This phenotypic trait was not associated to any specific CWAP gene. In general, S. pseudintermedius adherence to canine corneocytes was significantly higher compared to human corneocytes (p < 0.0001), but the MRSP ST71 strain of human origin adhered equally well to canine and human corneocytes, suggesting that MRSP ST71 may be able to adapt to human skin. The genetic basis of the enhanced in vitro adherence of ST71 needs to be elucidated as this phenotypic trait may be associated to the epidemiological success and zoonotic potential of this epidemic MRSP clone. PMID:24957656

Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions.

PubMed

Costa, Suelen B; Campos, Ana Carolina C; Pereira, Ana Claudia M; de Mattos-Guaraldi, Ana Luiza; Júnior, Raphael Hirata; Rosa, Ana Cláudia P; Asad, Lídia M B O

2014-09-01

During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the

Aeromonas species exhibit aggregative adherence to HEp-2 cells.

PubMed Central

Neves, M S; Nunes, M P; Milhomem, A M

1994-01-01

Clinical and environmental isolates of Aeromonas species (five A. hydrophila isolates, three A. caviae isolates, and two A. sobria isolates) were tested for their adherence to HEp-2 cells. Clinical isolates of A. hydrophila and A. sobria exhibited aggregative adherence similar to that presented by enteroadherent-aggregative Escherichia coli. Bacterial aggregates adhered to cells with a typical "stacked-brick" appearance. In contrast, A. caviae strains showed a diffuse adherence pattern. Images PMID:8027331

Performance evaluation of the Fiber Bragg Grating (FBG) sensing device and comparison with piezoelectric sensors for AE detection

NASA Astrophysics Data System (ADS)

Zhang, Chuang; Bond, Leonard J.

2017-02-01

Structural health monitoring (SHM) of engineering structures in service has assumed a significant role in assessing their safety and integrity. Several sensing modalities have been developed to monitor cracking, using acoustic emission (AE). Piezoelectric sensors are commonly used in AE systems, however, for some applications there are limitations and challenges. One alternative approach that is being investigated is using Fiber Bragg Grating (FBG) sensors which have emerged as a reliable, in situ and nondestructive tool in some applications for monitoring and diagnostics in large-scale structure. The main objective of this work is to evaluate and compare the AE sensing characteristics for FBG and piezoelectric sensors. A ball drop impact is used as the source for generating waves in an Aluminum plate. The source repeatability was verified and a 4-channel FBG AE detection device was used to compare with the response of PZT sensors, investigating amplitude and frequency response which can indicate sensitivity. The low sensitivity and slow sampling rate are identified, for the unit investigated, as the main factors limiting FBG engineering AE applications.

Adherence of Trichomonas vaginalis to cell culture monolayers.

PubMed

Martinotti, M G; Martinetto, P; Savoia, D

1986-06-01

The in vitro adherence to WISH cells of a pathogenic Trichomonas vaginalis strain was studied with a method utilizing thymidine-labeled protozoa. A marked dose-related adherence was observed. Glutaraldehyde fixed trichomonads were not adherent. The presence of fetal calf serum during the assay did not influence attachment. Concanavalin A inhibited adherence of protozoa. Complete or partial inhibition of adherence was achieved by preincubating WISH cells with Lactobacillus fermentum or Streptococcus agalactiae. Finally, pretreatment of cells with alpha-estradiol, beta-estradiol, progesterone and estrone influenced attachment of protozoa, whereas estriol was ineffective. These results suggest that adherence of Trichomonas vaginalis is dependent on different factors, whose manipulation may have clinical relevance in preventing recurrence of trichomonad vaginitis.

The association of fasting blood glucose (FBG) and waist circumference in northern adults in Iran: a population based study.

PubMed

Veghari, Gholamreza; Sedaghat, Mehdi; Joshaghani, Hamidreza; Banihashem, Samieh; Moharloei, Pooneh; Angizeh, Abdolhamid; Tazik, Ebrahim; Moghaddami, Abbas; Hajian-Tilaki, Karimollah; Zahedpasha, Yedolla

2014-01-06

The aim of this study was to evaluate the association between Fasting Blood Glucose (FBG) level and Waist Circumference (WC) in men and women among 25-65 years old people in the north of Iran. This was a cross-sectional and analytical research gender that carried out on the 1797 subjects (941 males and 856 females) between 25-65 years old using multistage cluster sampling technique. FBG was measured in the morning after a 12-hour fast and was determined by using laboratory kits (enzymatic methods) and spectrophotometry technique. Central obesity was defined based on World Health Organization criteria: waist circumference ≥102 cm and ≥88 cm in men and women, respectively. The SPSS.16 software was used for statistical analysis. As whole, the mean of FBG in women (98.3 ± 40.1 mg/dl) was higher than in men (94.6 ± 32.2 mg/dl). Also, the mean of WC in men 4.5 cm was lower than in women. In men, the mean of FBG statistically differs between normal and central obese subjects both in 35-45 year-age group (P = 0.001) and in 45-55 year-age group (P = 0.042). As whole, in men, the FBG level increased up 2.82 mg/dl in each 10 cm of WC with the highest rate in 35-45 year-age group. In totally, in women, the FBG level increased up 3.48 mg/dl in each 10 cm of WC and in 25-35 year-age group and it was higher than in other age groups. In men, the regression coefficients were constant with age increasing while in women it was decreased. Constant trend in men and decreasing trend in women with age was shown between FBG and WC. The cut-off point of WC for detecting of diabetes obtained 89 cm and 107 cm in men and women, respectively. The positive correlation was seen between WC and FBG level and it was declined with age in women. Cut-off point for detecting of diabetes in men was less than in women. WC is useable as a predictor of type 2 diabetes mellitus risk among adults in the north of Iran.

Fiber laser refractometer based on tunable bandpass filter tailored FBG reflection

NASA Astrophysics Data System (ADS)

Zhao, Junfa; Wang, Juan; Zhang, Cheng; Xu, Wei; Sun, Xiaodong; Bai, Hua; Chen, Liying

2018-02-01

A fiber laser refractometer based on single-mode-no-core-single-mode (SNS) structure cascaded with a FBG is proposed and experimentally demonstrated. The output wavelength of the fiber laser keeps constant because the oscillating wavelength is only determined by the central wavelength of the FBG which is insensitive to the surrounding refractive index (SRI). However, the output power is sensitive to the SRI because the intracavity loss of the fiber laser varies with the SRI. A cost-effective power detection refractometer with reflective operation can be realized through measuring the variation of the fiber laser's output power. The refractometer has a sensitivity of 195.52 dB/RIU and 365.52 dB/RIU in the RI range of 1.3330-1.3687 and 1.3687-1.4135, respectively. Moreover, the refractometer can also be used for temperature measurement through discriminating the output wavelength of the fiber laser.

Robust tracking of dexterous continuum robots: Fusing FBG shape sensing and stereo vision.

PubMed

Rumei Zhang; Hao Liu; Jianda Han

2017-07-01

Robust and efficient tracking of continuum robots is important for improving patient safety during space-confined minimally invasive surgery, however, it has been a particularly challenging task for researchers. In this paper, we present a novel tracking scheme by fusing fiber Bragg grating (FBG) shape sensing and stereo vision to estimate the position of continuum robots. Previous visual tracking easily suffers from the lack of robustness and leads to failure, while the FBG shape sensor can only reconstruct the local shape with integral cumulative error. The proposed fusion is anticipated to compensate for their shortcomings and improve the tracking accuracy. To verify its effectiveness, the robots' centerline is recognized by morphology operation and reconstructed by stereo matching algorithm. The shape obtained by FBG sensor is transformed into distal tip position with respect to the camera coordinate system through previously calibrated registration matrices. An experimental platform was set up and repeated tracking experiments were carried out. The accuracy estimated by averaging the absolute positioning errors between shape sensing and stereo vision is 0.67±0.65 mm, 0.41±0.25 mm, 0.72±0.43 mm for x, y and z, respectively. Results indicate that the proposed fusion is feasible and can be used for closed-loop control of continuum robots.

A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure.

PubMed

Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

2016-04-29

Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas.

FBG wavelength demodulation based on a radio frequency optical true time delay method.

PubMed

Wang, Jin; Zhu, Wanshan; Ma, Chenyuan; Xu, Tong

2018-06-01

A new fiber Bragg grating (FBG) wavelength shift demodulation method based on optical true time delay microwave phase detection is proposed. We used a microwave photonic link (MPL) to transport a radio frequency (RF) signal over a dispersion compensation fiber (DCF). The wavelength shift of the FBG will cause the time delay change of the optical carrier that propagates in an optical fiber with chromatic dispersion, which will result in the variation of the RF signal phase. A long DCF was adopted to enlarge the RF signal phase variation. An IQ mixer was used to measure the RF phase variation of the RF signal propagating in the MPL, and the wavelength shift of the FBG can be obtained by the measured RF signal phase variation. The experimental results showed that the wavelength shift measurement resolution is 2 pm when the group velocity dispersion of the DCF is 79.5 ps/nm and the frequency of the RF signal is 18 GHz. The demodulation time is as short as 0.1 ms. The measurement resolution can be improved simply by using a higher frequency of the RF signal and a longer DCF or larger chromatic dispersion value of the DCF.

Research on influence of different cover to the characteristic of FBG reflectance spectrum in vacuum thermal environment

NASA Astrophysics Data System (ADS)

Pei, Yifei; Zhang, Jingchuan; Zhang, Luosha; Liu, Yang; Zhang, Lina; Chen, Shiyu

2018-01-01

To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, two different kinds of sleeve compactly single model fiber covered by acrylate and polyimide are researched. Influence of the cover to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, transmission characteristic of single model fiber in high vacuum thermal environment is analyzed by solve the equation of heat conduction. Then, experimental program of influence on FBG reflection spectrum characteristics is designed and a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG in different coating single-mode transmission fiber under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different coating single-mode transmission fiber dropped to -196 ° from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the theoretical and experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 ° 25 ° temperature cycle) .

Experimental Modal Analysis and Dynaic Strain Fiber Bragg Gratings for Structural Health Monitoring of Composite Aerospace Structures

NASA Astrophysics Data System (ADS)

Panopoulou, A.; Fransen, S.; Gomez Molinero, V.; Kostopoulos, V.

2012-07-01

The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces the same result as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub- reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation of both structures was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able via the FBG responses to identify a potential failure.

Curvature and Temperature Measurement Based on a Few-Mode PCF Formed M-Z-I and an Embedded FBG.

PubMed

Liu, Hui; Yang, Hangzhou; Qiao, Xueguang; Wang, Yongqiang; Liu, Xiaochong; Lee, Yen-Sian; Lim, Kok-Sing; Ahmad, Harith

2017-07-27

We have experimentally demonstrated an optical fiber Mach-Zehnder interferometer (MZI) structure formed by a few-mode photonic crystal fiber (PCF) for curvature measurement and inscribed a fiber Bragg grating (FBG) in the PCF for the purpose of simultaneously measuring temperature. The structure consists of a PCF sandwiched between two multi-mode fibers (MMFs). Bending experimental results show that the proposed sensor has a sensitivity of -1.03 nm/m -1 at a curvature range from 10 m -1 to 22.4 m -1 , and the curvature sensitivity of the embedded FBG was -0.003 nm/m -1 . Temperature response experimental results showed that the MZI's wavelength, λ a , has a sensitivity of 60.3 pm/°C, and the FBG's Bragg wavelength, λ b , has sensitivity of 9.2 pm/°C in the temperature range of 8 to 100 °C. As such, it can be used for simultaneous measurement of curvature and temperature over ranges of 10 m -1 to 22.4 m -1 and 8 °C to 100 °C, respectively. The results show that the embedded FBG can be a good indicator to compensate the varying ambient temperature during a curvature measurement.

Aluminum alloy material structure impact localization by using FBG sensors

NASA Astrophysics Data System (ADS)

Zhu, Xiubin

2014-12-01

The aluminum alloy structure impact localization system by using fiber Bragg grating (FBG) sensors and impact localization algorithm was investigated. A four-FBG sensing network was established. And the power intensity demodulation method was initialized employing the narrow-band tunable laser. The wavelet transform was used to weaken the impact signal noise. And the impact signal time difference was extracted to build the time difference localization algorithm. At last, a fiber Bragg grating impact localization system was established and experimentally verified. The experimental results showed that in the aluminum alloy plate with the 500 mm*500 mm*2 mm test area, the maximum and average impact abscissa localization errors were 11 mm and 6.25 mm, and the maximum and average impact ordinate localization errors were 9 mm and 4.25 mm, respectively. The fiber Bragg grating sensors and demodulation system are feasible to realize the aviation aluminum alloy material structure impact localization. The research results provide a reliable method for the aluminum alloy material structure impact localization.

A IR-Femtosecond Laser Hybrid Sensor to Measure the Thermal Expansion and Thermo-Optical Coefficient of Silica-Based FBG at High Temperatures.

PubMed

Li, Litong; Lv, Dajuan; Yang, Minghong; Xiong, Liangming; Luo, Jie

2018-01-26

In this paper, a hybrid sensor was fabricated using a IR-femtosecond laser to measure the thermal expansion and thermo-optical coefficient of silica-based fiber Bragg gratings (FBGs). The hybrid sensor was composed of an inline fiber Fabry-Perot interferometer (FFPI) cavity and a type-II FBG. Experiment results showed that the type-II FBG had three high reflectivity resonances in the wavelength ranging from 1100 to 1600 nm, showing the peaks in 1.1, 1.3 and 1.5 μm, respectively. The thermal expansion and thermo-optical coefficient (1.3 μm, 1.5 μm) of silica-based FBG, under temperatures ranging from 30 to 1100 °C, had been simultaneously calculated by measuring the wavelength of the type-II FBG and FFPI cavity length.

Strain characteristics of the silica-based fiber Bragg gratings for 30-273 K

NASA Astrophysics Data System (ADS)

Li, Litong; Lv, Dajuan; Yang, Minghong; Xiong, Liangming; Luo, Jie; Tan, Lu

2018-06-01

This work studied the strain coefficient of silica-based fiber Bragg grating (FBG) at cryogenic temperatures. A dynamic temperature test with an oxygen-free copper specimen in the temperature range of 30-273 K was designed. The relationship between the strain coefficient and temperature could be characterized by three-order polynomial. A static tensile test was carried out in liquid nitrogen environment verified the effectiveness of the dynamic results. Good correlation was obtained from the two experiment results. Finally, the factors affecting the measurement error were discussed.

A mannose-specific adherence mechanism in Lactobacillus plantarum conferring binding to the human colonic cell line HT-29.

PubMed

Adlerberth, I; Ahrne, S; Johansson, M L; Molin, G; Hanson, L A; Wold, A E

1996-07-01

Two Lactobacillus plantarum strains of human intestinal origin, strains 299 (= DSM 6595) and 299v (= DSM 9843), have proved to be efficient colonizers of the human intestine under experimental conditions. These strains and 17 other L. plantarum strains were tested for the ability to adhere to cells of the human colonic cell line HT-29.L.plantarum 299 and 299v and nine other L. plantarum strains, including all six strains that belong to the same genetic subgroup as L. plantarum 299 and 299v, adhered to HT-29 cells in a manner that could be inhibited by methyl-alpha-D-mannoside. The ability to adhere to HT-29 cells correlated with an ability to agglutinate cells of Saccharomyces cerevisiae and erythrocytes in a mannose-sensitive manner and with adherence to D-mannose-coated agarose beads. L. plantarum 299 and 299v adhered to freshly isolated human colonic and ileal enterocytes, but the binding was not significantly inhibited by methyl-alpha-D-mannoside. Periodate treatment of HT-29 cells abolished mannose-sensitive adherence, confirming that the cell-bound receptor was of carbohydrate nature. Proteinase K treatment of the bacteria also abolished adherence, indicating that the binding involved protein structures on the bacterial cell surface. Thus, a mannose-specific adhesin has been identified in L. plantarum; this adhesin could be involved in the ability to colonize the intestine.

A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure

PubMed Central

Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

2016-01-01

Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas. PMID:27136564

The association between the levels of CRP, IL-10, PLA2, Fbg and prognosis in traumatic fracture of lower limb.

PubMed

Jiao, Jing; Wang, Jun-Wen; Xiao, Fei; Huang, Yu-Cheng

2016-11-01

The aim of the present study was to examine changes of sera levels of C-reactive protein (CRP), interleukin-10 (IL-10), phospholipase A2 (PLA2) and fibrinogen β polypeptide chain gene (Fbg) in patients with traumatic fracture of lower limb, and to evaluate their association with prognosis. The changes in sera levels of CRP, IL-10, PLA2 and Fbg were observed at the time of injury, 24 h, and 5 and 7 days after surgery in 90 patients with traumatic fracture of lower limb. In addition, 50 cases, who presented for health examination, were included as the normal controls. The expression of sera levels of CRP, IL-10, PLA2 and Fbg in patients with traumatic fracture of lower limb, was markedly higher than that in the normal controls prior to surgery (P<0.05). The concentration of CRP significantly increased within 24 h after emergency, but decreased gradually as the wound healed, compared to the controls. Pre- and postoperative IL-10 levels increased within 24 h and then decreased gradually. The level of PLA2 in patients before and after surgery was increased, and then decreased gradually. The level of Fbg in patients with trauma was increased after 24 h and then decreased, and increased gradually. The correlation of serum CRP and IL-10 levels (r=0.634, P<0.05), and that of PLA2 and IL-10 levels (r=0.617, P<0.05) were positive. In conclusion, the expression of CRP, IL-10, PLA2 and Fbg levels in traumatic fracture of lower limb markedly increased and was closely associated with prognosis. CRP, IL-10, PLA2 and Fbg levels may therefore serve as useful indexes in determining the progression and prognosis of patients with traumatic fracture of lower limb.

Dynamic optical arbitrary waveform shaping based on cascaded optical modulators of single FBG.

PubMed

Chen, Jingyuan; Li, Peili

2015-08-10

A dynamic optical arbitrary waveform generation (O-AWG) with amplitude and phase independently controlled in optical modulators of single fiber Bragg Grating (FBG) has been proposed. This novel scheme consists of several optical modulators. In the optical modulator (O-MOD), a uniform FBG is used to filter spectral component of the input signal. The amplitude is controlled by fiber stretcher (FS) in Mach-Zehnder interference (MZI) structure through interference of two MZI arms. The phase is manipulated via the second FS in the optical modulator. This scheme is investigated by simulation. Consequently, optical pulse trains with different waveforms as well as pulse trains with nonuniform pulse intensity, pulse spacing and pulse width within each period are obtained through FSs adjustment to alter the phase shifts of signal in each O-MOD.

Research on FBG-Based CFRP Structural Damage Identification Using BP Neural Network

NASA Astrophysics Data System (ADS)

Geng, Xiangyi; Lu, Shizeng; Jiang, Mingshun; Sui, Qingmei; Lv, Shanshan; Xiao, Hang; Jia, Yuxi; Jia, Lei

2018-06-01

A damage identification system of carbon fiber reinforced plastics (CFRP) structures is investigated using fiber Bragg grating (FBG) sensors and back propagation (BP) neural network. FBG sensors are applied to construct the sensing network to detect the structural dynamic response signals generated by active actuation. The damage identification model is built based on the BP neural network. The dynamic signal characteristics extracted by the Fourier transform are the inputs, and the damage states are the outputs of the model. Besides, damages are simulated by placing lumped masses with different weights instead of inducing real damages, which is confirmed to be feasible by finite element analysis (FEA). At last, the damage identification system is verified on a CFRP plate with 300 mm × 300 mm experimental area, with the accurate identification of varied damage states. The system provides a practical way for CFRP structural damage identification.

Etched FBG coated with polyimide for simultaneous detection the salinity and temperature

NASA Astrophysics Data System (ADS)

Luo, Dong; Ma, Jianxun; Ibrahim, Zainah; Ismail, Zubaidah

2017-06-01

In marine environment, concrete structures can corrode because of the PH alkalinity of concrete paste; and the salinity PH is heavily related with the concentration of salt in aqueous solutions. In this study, an optical fiber salinity sensor is proposed on the basis of an etched FBG (EFBG) coated with a layer of polyimide. Chemical etching is employed to reduce the diameter of FBG and to excite Cladding Mode Resonance Wavelengths (CMRWs). CMRW and Fundamental Mode Resonance Wavelength (FMRW) can be used to measure the Refractive index (RI) and temperature of salinity. The proposed sensor is then characterized with a matrix equation. Experimental results show that FMRW and 5th CMRW have the detection sensitivities of 15.407 and 125.92 nm/RIU for RI and 0.0312 and 0.0435 nm/°C for temperature, respectively. The proposed sensor can measure salinity and temperature simultaneously.

Fusion of a FBG-based health monitoring system for wind turbines with a fiber-optic lightning detection system

NASA Astrophysics Data System (ADS)

Krämer, Sebastian G. M.; Wiesent, Benjamin; Müller, Mathias S.; Puente León, Fernando; Méndez Hernández, Yarú

2008-04-01

Wind turbine blades are made of composite materials and reach a length of more than 42 meters. Developments for modern offshore turbines are working on about 60 meters long blades. Hence, with the increasing height of the turbines and the remote locations of the structures, health monitoring systems are becoming more and more important. Therefore, fiber-optic sensor systems are well-suited, as they are lightweight, immune against electromagnetic interference (EMI), and as they can be multiplexed. Based on two separately existing concepts for strain measurements and lightning detection on wind turbines, a fused system is presented. The strain measurement system is based on a reflective fiber-Bragg-grating (FBG) network embedded in the composite structure of the blade. For lightning detection, transmissive &fiber-optic magnetic field sensors based on the Faraday effect are used to register the lightning parameters and estimate the impact point. Hence, an existing lightning detection system will be augmented, due to the fusion, by the capability to measure strain, temperature and vibration. Load, strain, temperature and impact detection information can be incorporated into the turbine's monitoring or SCADA system and remote controlled by operators. Data analysis techniques allow dynamic maintenance scheduling to become a reality, what is of special interest for the cost-effective maintenance of large offshore or badly attainable onshore wind parks. To prove the feasibility of this sensor fusion on one optical fiber, interferences between both sensor systems are investigated and evaluated.

PWAS EMIS-ECIS Active Carbon Filter Residual Life Estimation Methodology

DTIC Science & Technology

2013-09-23

change in the EMIS spectrum. This method is similar to the full width at half maximum (FWHM) method implemented in the fiber Bragg grating ( FBG ), where...the intensity of the light reflected by the FBG at the half peak frequency is used to detect the strain change in the FBG . 4 W911NF-11-1-0210...grating ( FBG ), where the intensity of the light reflected by the FBG at the half peak frequency is used to detect the strain change in the FBG . A brief

High sensitive FBG load cell for icing of overhead transmission lines

NASA Astrophysics Data System (ADS)

Mao, Naiqiang; Ma, Guoming; Li, Chengrong; Li, Yabo; Shi, Cheng; Du, Yue

2017-04-01

Heavy ice coating of overhead transmission lines created the serious threat on the safe operation of power grid. The measurement of conductor icing had been an effective and reliable methods to prevent potential risks, such as conductor breakage, insulator flashover and tower collapse. Because of the advantages of immunity to electromagnetic interference and no demand for power supply in site, the optical load cell has been widely applied in monitoring the ice coating of overhead transmission lines. In this paper, we have adopted the shearing structure with additional grooves as elastic element of load cell to detect the eccentric load. Then, two welding package fiber Bragg gratings (FBGs) were mounted onto the grooves of elastic element with a direction deviation of 90° to eliminate temperature effects on strain measurement without extra FBG. After that, to avoid the occurrence of load cell breakage in heavy load measurement, the protection part has been proposed and added to the elastic element. The results of tension experiments indicate that the resolution of the load cell is 7.78 N in the conventional measuring range (0-10 kN). And in addition, the load cell proposed in this paper also has a good performance in actual experiment in which the load and temperature change simultaneously.

[The Research on Optic Fiber FBG Corrosion Sensor Based on the Analysis of the Spectral Characteristics].

PubMed

Zhang, Jun; Zeng, Jie; Wang, Bo; Wang, Wen-juan; Liang, Da-kai; Liu, Xiao-ying

2016-03-01

Aiming at meeting the need of aluminum corrosion monitoring in aerospace field, a pre-load type fiber grating corrosion sensor based on an aluminum thin tube structure is proposed. The corrosion sensor of aluminum alloy structure in-service monitoring mechanism is studied, a theoretical model about the relation of FBG reflection spectral characteristics and aluminum thickness variation is also obtained. Optical fiber grating corrosion monitoring test system based on the capillary structure of aluminum alloy is constructed by acid-base environment. The problem of cross sensitivity of temperature and strain is solved by configuring an optical fiber grating which is not affected by strain and only sensitive to temperature inside the aluminum alloy tube. The results shows that he aluminum tube packaging design not only can sense the effects of corrosion on the mechanical properties, but also can interference shielding effect of corrosion on the tube optical fiber sensing device. With the deepening of the metal tube corrosion and aluminum alloy tube thickness gradually thinning, fiber grating reflective spectrum gradually shift to the short wavelength and the wall thickness and the grating center wavelength offset has a good monotonic relation. These characteristics can provide useful help to further research corrosion online monitoring based on optic fiber sensor.

Dynamic Sensing Performance of a Point-Wise Fiber Bragg Grating Displacement Measurement System Integrated in an Active Structural Control System

PubMed Central

Chuang, Kuo-Chih; Liao, Heng-Tseng; Ma, Chien-Ching

2011-01-01

In this work, a fiber Bragg grating (FBG) sensing system which can measure the transient response of out-of-plane point-wise displacement responses is set up on a smart cantilever beam and the feasibility of its use as a feedback sensor in an active structural control system is studied experimentally. An FBG filter is employed in the proposed fiber sensing system to dynamically demodulate the responses obtained by the FBG displacement sensor with high sensitivity. For comparison, a laser Doppler vibrometer (LDV) is utilized simultaneously to verify displacement detection ability of the FBG sensing system. An optical full-field measurement technique called amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to provide full-field vibration mode shapes and resonant frequencies. To verify the dynamic demodulation performance of the FBG filter, a traditional FBG strain sensor calibrated with a strain gauge is first employed to measure the dynamic strain of impact-induced vibrations. Then, system identification of the smart cantilever beam is performed by FBG strain and displacement sensors. Finally, by employing a velocity feedback control algorithm, the feasibility of integrating the proposed FBG displacement sensing system in a collocated feedback system is investigated and excellent dynamic feedback performance is demonstrated. In conclusion, our experiments show that the FBG sensor is capable of performing dynamic displacement feedback and/or strain measurements with high sensitivity and resolution. PMID:22247683

Impact of fiber ring laser configuration on detection capabilities in FBG based sensor systems

NASA Astrophysics Data System (ADS)

Osuch, Tomasz; Kossek, Tomasz; Markowski, Konrad

2014-11-01

In this paper fiber ring lasers (FRL) as interrogation units for distributed fiber Bragg grating (FBG) based sensor networks are studied. In particular, two configurations of the fiber laser with erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) as gain medium were analyzed. In the case of EDFA-based fiber interrogation systems, CW as well as active-mode locking operation were taken into account. The influence of spectral overlapping of FBGs spectra on detection capabilities of examined FRLs are presented. Experimental results show that the SOA-based fiber laser interrogation unit can operate as a multi-parametric sensing system. In turn, using an actively mode-locked fiber ring laser with an EDFA, an electronically switchable FBG based sensing system can be realized.

A novel MUX/DEMUX based on few-mode FBG for mode division multiplexing system

NASA Astrophysics Data System (ADS)

Han, Yueyu; Hu, Guijun

2016-05-01

In this paper, a novel mode multiplexer/demultiplexer (MUX/DEMUX) based on few-mode fiber Bragg gratings (FBG) has been proposed. The principle of the MUX/DEMUX based on few-mode FBG has been described in detail, and crosstalk of better than -20 dB is obtained experimentally. Then a 2×2 division multiplexing (MDM) system has been established with the MUX/DEMUX we proposed. The transmission experiment of 2×10 Gbps PRBS has been achieved successfully, which are carried by LP01 mode and LP11 mode, respectively. When the receiver sensitivity is greater than -14 dB m and -10 dB m, the BER can both reach 10-3 for B2B and 10 km transmission, respectively.

EMD self-adaptive selecting relevant modes algorithm for FBG spectrum signal

NASA Astrophysics Data System (ADS)

Chen, Yong; Wu, Chun-ting; Liu, Huan-lin

2017-07-01

Noise may reduce the demodulation accuracy of fiber Bragg grating (FBG) sensing signal so as to affect the quality of sensing detection. Thus, the recovery of a signal from observed noisy data is necessary. In this paper, a precise self-adaptive algorithm of selecting relevant modes is proposed to remove the noise of signal. Empirical mode decomposition (EMD) is first used to decompose a signal into a set of modes. The pseudo modes cancellation is introduced to identify and eliminate false modes, and then the Mutual Information (MI) of partial modes is calculated. MI is used to estimate the critical point of high and low frequency components. Simulation results show that the proposed algorithm estimates the critical point more accurately than the traditional algorithms for FBG spectral signal. While, compared to the similar algorithms, the signal noise ratio of the signal can be improved more than 10 dB after processing by the proposed algorithm, and correlation coefficient can be increased by 0.5, so it demonstrates better de-noising effect.

Research on the demodulation techniques of long-period fiber gratings strain sensing with low cost

NASA Astrophysics Data System (ADS)

Wang, Qingwei; Liu, Yueming; Tian, Weijian; Feng, Guilan

2012-10-01

The working principle of LPFG(Long-Period Fiber Grating) is based on coupling effect between propagating core-mode and co-propagating cladding-modes. The effective refractive index of cladding-modes could be obviously influenced by the environmental changes resulting in LPFG more sensitive than FBG (Fiber Bragg Grating) in sensing areas, such as temperature, strain, concentration, bending and etc. LPFG should have more potential in the field of sensors compared with FBG. One of the challenges in using LPFG for environmental sensing is how to interrogate the signal from the LPFG transmission spectrum, due to the large spectral range of the resonant dip. Nowadays the application of LPFG is normally limited in signal interrogation of FBG as optical edge filter. The signal interrogation of LPFG itself needs further research. Presently research on signal interrogation of fiber grating focuses on wavelength interrogation. The aim of wavelength interrogation is to get the wavelength shift caused by environmental change. To solve these problems, a kind of strain sensing interrogation technique for LPFG with low-cost based on tunable FBGs has been developed. Comparing with the method using Fabry-Perot cavity, tunable FBGs can lower the cost with the guarantee of sensing precision. The cost is further lowered without using expensive optical instruments such as optical switch. The problem of temperature cross-sensitivity was solved by using reference gratings. An experiment was performed to demonstrate the interrogation system. And in the experiment, the sensing signal of LPFG applied 0-1300μɛ was successfully interrogated. The results of the interrogation system and OSA are similar.

Novel glucose fiber sensor combining ThFBG with GOD

NASA Astrophysics Data System (ADS)

Li, Mengmeng; Zhou, Ciming; Fan, Dian; Ou, Yiwen

2016-10-01

We propose a novel glucose fiber optic sensor combining a thinned cladding fiber Bragg grating (ThFBG) with glucose oxidase (GOD). By immobilizing GOD on the surface of a ThFBG, the fabricated sensor can obtain a high specificity to glucose. Because of the evanescent field, the sensor is very sensitive to the ambient refractive index change arising from the catalytic reaction between glucose and GOD. A four-level fiber model was simulated and verified the precision of the sensing principle. Two methods, glutaraldehyde crosslinking method (GCM) and 3-aminopropyl triethoxysilane covalent coupling method (ATCCM), were experimentally utilized to immobilize GOD. And sensor fabricated with the method ATCCM shows a measurement range of 0-0.82 mg/mL which is better than the sensor fabricated with the method GCM with measurement range of 0-0.67 mg/mL under the same condition. By using ATCCM to immobilize GOD with different concentrations, three sensors were fabricated and used for glucose measurement by monitoring the Bragg wavelength (λb) shifts, the results indicate a good linear relationship between wavelength shift and glucose concentration within a specific range, and the measurement range increases as GOD concentration increases. The highest sensitivity of sensor reaches up to 0.0549 nm/(mg.mL-1). The proposed sensor has distinct advantages in sensing structure, cost and specificity.

Quantitative method for gait pattern detection based on fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Ding, Lei; Tong, Xinglin; Yu, Lie

2017-03-01

This paper presents a method that uses fiber Bragg grating (FBG) sensors to distinguish the temporal gait patterns in gait cycles. Unlike most conventional methods that focus on electronic sensors to collect those physical quantities (i.e., strains, forces, pressure, displacements, velocity, and accelerations), the proposed method utilizes the backreflected peak wavelength from FBG sensors to describe the motion characteristics in human walking. Specifically, the FBG sensors are sensitive to external strain with the result that their backreflected peak wavelength will be shifted according to the extent of the influence of external strain. Therefore, when subjects walk in different gait patterns, the strains on FBG sensors will be different such that the magnitude of the backreflected peak wavelength varies. To test the reliability of the FBG sensor platform for gait pattern detection, the gold standard method using force-sensitive resistors (FSRs) for defining gait patterns is introduced as a reference platform. The reliability of the FBG sensor platform is determined by comparing the detection results between the FBG sensors and FSRs platforms. The experimental results show that the FBG sensor platform is reliable in gait pattern detection and gains high reliability when compared with the reference platform.

Adherence Reduction of Campylobacter jejuni and Campylobacter coli Strains to HEp-2 Cells by Mannan Oligosaccharides and a High-Molecular-Weight Component of Cranberry Extract.

PubMed

Ramirez-Hernandez, Alejandra; Rupnow, John; Hutkins, Robert W

2015-08-01

Campylobacter infections are a leading cause of human bacterial gastroenteritis in the United States and are a major cause of diarrheal disease throughout the world. Colonization and subsequent infection and invasion of Campylobacter require that the bacteria adhere to the surface of host cells. Agents that inhibit adherence could be used prophylactically to reduce Campylobacter carriage and infection. Mannan oligosaccharides (MOS) have been used as a feed supplement in livestock animals to improve performance and to replace growth-promoting antibiotics. However, MOS and other nondigestible oligosaccharides may also prevent pathogen colonization by inhibiting adherence in the gastrointestinal tract. In addition, plant extracts, including those derived from cranberries, have been shown to have antiadherence activity against pathogens. The goal of this study was to assess the ability of MOS and cranberry fractions to serve as antiadherence agents against strains of Campylobacter jejuni and Campylobacter coli. Adherence experiments were performed using HEp-2 cells. Significant reductions in adherence of C. jejuni 29438, C. jejuni 700819, C. jejuni 3329, and C. coli 43485 were observed in the presence of MOS (up to 40 mg/ml) and with a high-molecular-weight fraction of cranberry extract (up to 3 mg/ml). However, none of the tested materials reduced adherence of C. coli BAA-1061. No additive effect in adherence inhibition was observed for an MOS-cranberry blend. These results suggest that both components, MOS and cranberry, could be used to reduce Campylobacter colonization and carriage in livestock animals and potentially limit human exposure to this pathogen.

Thermal strain measurement of EAST tungsten divertor component with bare fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Wang, Xingli; Wang, Wanjing; Wang, Jichao; Wei, Ran; Sun, Zhaoxuan; Li, Qiang; Xie, Chunyi; Luo, Guang-Nan

2017-12-01

Fiber Bragg Gratings (FBGs) have been widely used in the sensor field to monitor temperature and strain. However, the weak mechanical property of optical fibers and insufficient heat-resistant property of general optic-fiber sensors have prevented it from being widely used, such as in some extreme engineering situations. In this work, a bare FBG sensor system had been introduced to measure thermal strain of an Experimental Advanced Superconducting Tokamak tungsten divertor component under baking condition. This strain measurement system had withstood as high temperature as 210 °C and finished the measurement experiment successfully. Meaningful measurement results had been obtained and analyzed, which showed the applicability of such a bare fiber grating sensor system and as well contributed to studying on tungsten divertor's thermal strain conditions.

Temperature and humidity dependent performance of FBG-strain sensors embedded in carbon/epoxy composites

NASA Astrophysics Data System (ADS)

Frövel, Malte; Carrión, Gabriel; Gutiérrez, César; Moravec, Carolina; Pintado, José María

2009-03-01

Fiber Bragg Grating Sensors, FBGSs, are very promising for Structural Health Monitoring, SHM, of aerospace vehicles due to their capacity to measure strain and temperature, their lightweight harnesses, their multiplexing capacities and their immunity to electromagnetic interferences, within others. They can be embedded in composite materials that are increasingly forming an important part of aerospace structures. The use of embedded FBGSs for SHM purposes is advantageous, but their response under all operative environmental conditions of an aerospace structure must be well understood for the necessary flight certification of these sensors. This paper describes the first steps ahead for a possible in future flight certification of FBGSs embedded in carbon fiber reinforced plastics, CFRP. The investigation work was focused on the validation of the dependence of the FBGS's strain sensitivity in tensile and compression load, in dry and humid condition and in a temperature range from -150°C to 120°C. The test conditions try to simulate the in service temperature and humidity range and static load condition of military aircraft. FBGSs with acrylic and with polyimide coating have been tested. The FBGSs are embedded in both, unidirectional and quasi isotropic carbon/epoxy composite material namely M21/T800 and also MTM-45-1/IM7. Conventional extensometers and strain gages have been used as reference strain sensors. The performed tests show an influence of the testing temperatures, the dry or wet specimen condition, the load direction and the coating material on the sensor strain sensitivity that should be taken into account when using these sensors.

Orthodontic mechanics using mini-implant measured by FBG

NASA Astrophysics Data System (ADS)

Trannin, Pamela G.; Milczewski, Maura S.; de Oliveira, Walmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

2015-07-01

The magnitude of the force generated during orthodontic mechanics anchored in mini-implant in a maxilla model was analyzed. Data was collected during the insertion of the mini-implant and at the moment of applying forces to the structure of the maxilla and dentition. To obtain quantitative results, the Fibre Bragg Gratings (FBG) were inserted in an elastomeric material reproducing a maxilla model. It was observed levels of forces of approximately 3,78N next to the root of first premolar by the insertion of the mini-implant and different levels of the force to different orthodontic mechanics applied on the dental system.

Increased Chain Length Promotes Pneumococcal Adherence and Colonization

PubMed Central

Rodriguez, Jesse L.; Dalia, Ankur B.

2012-01-01

Streptococcus pneumoniae is a mucosal pathogen that grows in chains of variable lengths. Short-chain forms are less likely to activate complement, and as a consequence they evade opsonophagocytic clearance more effectively during invasive disease. When grown in human nasal airway surface fluid, pneumococci exhibited both short- and long-chain forms. Here, we determined whether longer chains provide an advantage during colonization when the organism is attached to the epithelial surface. Chain-forming mutants and the parental strain grown under conditions to promote chain formation showed increased adherence to human epithelial cells (A549 cells) in vitro. Additionally, adherence to A549 cells selected for longer chains within the wild-type strain. In vivo in a murine model of colonization, chain-forming mutants outcompeted the parental strain. Together, our results demonstrate that morphological heterogeneity in the pneumococcus may promote colonization of the upper respiratory tract by enhancing the ability of the organism to bind to the epithelial surface. PMID:22825449

Strain-specific spleen remodelling in Plasmodium yoelii infections in Balb/c mice facilitates adherence and spleen macrophage-clearance escape

PubMed Central

Martin-Jaular, Lorena; Ferrer, Mireia; Calvo, Maria; Rosanas-Urgell, Anna; Kalko, Susana; Graewe, Stefanie; Soria, Guadalupe; Cortadellas, Núria; Ordi, Jaume; Planas, Anna; Burns, James; Heussler, Volker; del Portillo, Hernando A

2011-01-01

Knowledge of the dynamic features of the processes driven by malaria parasites in the spleen is lacking. To gain insight into the function and structure of the spleen in malaria, we have implemented intravital microscopy and magnetic resonance imaging of the mouse spleen in experimental infections with non-lethal (17X) and lethal (17XL) Plasmodium yoelii strains. Noticeably, there was higher parasite accumulation, reduced motility, loss of directionality, increased residence time and altered magnetic resonance only in the spleens of mice infected with 17X. Moreover, these differences were associated with the formation of a strain-specific induced spleen tissue barrier of fibroblastic origin, with red pulp macrophage-clearance evasion and with adherence of infected red blood cells to this barrier. Our data suggest that in this reticulocyte-prone non-lethal rodent malaria model, passage through the spleen is different from what is known in other Plasmodium species and open new avenues for functional/structural studies of this lymphoid organ in malaria. PMID:20923452

High sensitivity optical fiber liquid level sensor based on a compact MMF-HCF-FBG structure

NASA Astrophysics Data System (ADS)

Zhang, Yunshan; Zhang, Weigang; Chen, Lei; Zhang, Yanxin; Wang, Song; Yan, Tieyi

2018-05-01

An ultra-high sensitivity fiber liquid level sensor based on wavelength demodulation is proposed and demonstrated. The sensor is composed of a segment of multimode fiber and a large aperture hollow-core fiber assisted by a fiber Bragg grating (FBG). Interference occurs due to core mismatching and different modes with different effective refractive indices. The experimental results show that the liquid level sensitivity of the sensor is 1.145 nm mm‑1, and the linearity is up to 0.996. The dynamic temperature compensation of the sensor can be achieved by cascading an FBG. Considering the high sensitivity and compact structure of the sensor, it can be used for real-time intelligent monitoring of tiny changes in liquid level.

The role of Mycobacterium avium complex fibronectin attachment protein in adherence to the human respiratory mucosa.

PubMed

Middleton, A M; Chadwick, M V; Nicholson, A G; Dewar, A; Groger, R K; Brown, E J; Wilson, R

2000-10-01

Mycobacterium avium complex (MAC) are opportunistic respiratory pathogens that infect non-immunocompromised patients with established lung disease, although they can also cause primary infections. The ability to bind fibronectin is conserved among many mycobacterial species. We have investigated the adherence of a sputum isolate of MAC to the mucosa of organ cultures constructed with human tissue and the contribution of M. avium fibronectin attachment protein (FAP) to the process. MAC adhered to fibrous, but not globular mucus, and to extracellular matrix (ECM) in areas of epithelial damage, but not to intact extruded cells and collagen fibres. Bacteria occasionally adhered to healthy unciliated epithelium and to cells that had degenerated exposing their contents, but never to ciliated cells. The results obtained with different respiratory tissues were similar. Two ATCC strains of MAC gave similar results. There was a significant reduction (P < 0.05) in the number of bacteria adhering to ECM after preincubation of bacteria with fibronectin and after preincubation of the tissue with M. avium FAP in a concentration-dependant manner. The number of bacteria adhering to fibrous mucus was unchanged. Immunogold labelling demonstrated fibronectin in ECM as well as in other areas of epithelial damage, but only ECM bound FAP. A Mycobacterium smegmatis strain had the same pattern of adherence to the mucosa as MAC. When the FAP gene was deleted, the strain demonstrated reduced adherence to ECM, and adherence was restored when the strain was transfected with an M. avium FAP expression construct. We conclude that MAC adheres to ECM in areas of epithelial damage via FAP and to mucus with a fibrous appearance via another adhesin. Epithelial damage exposing ECM and poor mucus clearance will predispose to MAC airway infection.

In vitro model for Campylobacter pylori adherence properties.

PubMed Central

Neman-Simha, V; Mégraud, F

1988-01-01

The adherence of 12 strains of Campylobacter pylori was studied on four cell lines. Immunofluorescence and scanning and transmission electron microscopy were used to visualize the bacteria. A heavy adherence to the epithelial cell line HEp-2 and to the intestinal cell line Int-407 was noted. By transmission electron microscopy, a close association between bacteria and cells in the form of cup-like structures was observed, but pedestals were not present. Images PMID:3182085

Measurement of temperature and pressure on the surface of a blunt cone using FBG sensor in hypersonic wind tunnel

NASA Astrophysics Data System (ADS)

Prasad, A. S. Guru; Sharath, U.; Nagarjun, V.; Hegde, G. M.; Asokan, S.

2013-09-01

Measurement of temperature and pressure exerted on the leeward surface of a blunt cone specimen has been demonstrated in the present work in a hypersonic wind tunnel using fiber Bragg grating (FBG) sensors. The experiments were conducted on a 30° apex-angle blunt cone with 51 mm base diameter at wind flow speeds of Mach 6.5 and 8.35 in a 300 mm hypersonic wind tunnel of Indian Institute of Science, Bangalore. A special pressure insensitive temperature sensor probe along with the conventional bare FBG sensors was used for explicit temperature and aerodynamic pressure measurement respectively on the leeward surface of the specimen. computational fluid dynamics (CFD) simulation of the flow field around the blunt cone specimen has also been carried out to obtain the temperature and pressure at conditions analogous to experiments. The results obtained from FBG sensors and the CFD simulations are found to be in good agreement with each other.

Inhibition of Enterococcus faecium adherence to collagen by antibodies against high-affinity binding subdomains of Acm.

PubMed

Nallapareddy, Sreedhar R; Sillanpää, Jouko; Ganesh, Vannakambadi K; Höök, Magnus; Murray, Barbara E

2007-06-01

Strains of Enterococcus faecium express a cell wall-anchored protein, Acm, which mediates adherence to collagen. Here, we (i) identify the minimal and high-affinity binding subsegments of Acm and (ii) show that anti-Acm immunoglobulin Gs (IgGs) purified against these subsegments reduced E. faecium TX2535 strain collagen adherence up to 73 and 50%, respectively, significantly more than the total IgGs against the full-length Acm A domain (28%) (P < 0.0001). Blocking Acm adherence with functional subsegment-specific antibodies raises the possibility of their use as therapeutic or prophylactic agents.

Newly-synthesized chalcones-inhibition of adherence and biofilm formation of methicillin-resistant Staphylococcus aureus

PubMed Central

Bozic, Dragana D.; Milenkovic, Marina; Ivkovic, Branka; Cirkovic, Ivana

2014-01-01

Biofilm formation and adherence of bacteria to host tissue are one of the most important virulence factors of methicillin-resistant strains of Staphylococcus aureus (MRSA). The number of resistant strains is seriously increasing during the past years and bacteria have become resistant, not only to methicillin, but also to other commonly used antistaphylococcal antibiotics. There is a great need for discovering a novel antimicrobial agent for the treatment of staphylococcal infections. One of the most promising groups of compounds appears to be chalcones. In present study we evaluated the in vitro effect of three newly synthesized chalcones: 1,3- Bis-(2-hydroxy-phenyl)-propenone, 3-(3-Hydroxy-phenyl)-1-(2-hydroxy-phenyl)-propenone and 3-(4-Hydroxy-phenyl)-1-(2-hydroxy-phenyl)-propenone on glycocalyx production, biofilm formation and adherence to human fibronectin of clinical isolates and laboratory control strain of MRSA (ATCC 43300). Subinhibitory concentrations of the tested compounds reduced the production of glycocalyx, biofilm formation and adherence to human fibronectin of all MRSA strains. Inhibition of biofilm formation was dose dependent and the most effective was 1,3- Bis-(2-hydroxy-phenyl)-propenone. In our study we demonstrated that three newly-synthesized chalcones exhibited significant effect on adherence and biofilm formation of MRSA strains. Chalcones may be considered as promising new antimicrobial agents that can be used for prevention of staphylococcal infections or as adjunct to antibiotics in conventional therapy. PMID:24948943

Safety monitoring of the FBG sensor in respect of radioactivity and deformation measurement of a silo structure for radioactive waste disposal

NASA Astrophysics Data System (ADS)

Kim, Ki-Soo; Cho, Seong-Kyu

2015-07-01

The FBG sensor has globally been commercialized in various fields that is actively applied in Korea as well. Especially it is widely used as a structural monitoring sensor in civil engineering and construction structures due to its advantages including electrical stability, chemical stability and multiplexing. This report aims to introduce safety inspection of the FBG sensor in respect of radioactivity which has been applied to a silo structure for radioactive waste disposal as an example.

Strain and temperature measurement in pultrusion processes by fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Tucci, Fausto; Rubino, Felice; Carlone, Pierpaolo

2018-05-01

Injection Pultrusion (IP) is one of the most effective processes, in terms of productivity and costs, to manufacture fiber reinforced polymers. In IP roving of fiber are driven through an injection chamber in which they are impregnated by the resin and then formed in a shaped die. The die is heated in order to cure the resin. Pultruded products are in most cases characterized by constant cross-section profile, whereas unidirectional long fibers are mainly used as reinforcing material. Two relevant phenomena occur within the injection chamber and the heated die, namely the impregnation of the fibers and the polymerization of the resin. Furthermore, thermal expansion, resin chemical shrinkage and the interaction between the die and the impregnated fibers strongly influence the process [1]. Clearly, thermal and mechanical fields significantly impact on these strictly chained behaviours. The use of thermocouples to evaluate temperature within pultrusion die is already widespread, but they are not capable to acquire any information concerning stress-strain levels. In the present work Fibers Bragg Gratings (FBG) sensors were used to measure thermal and strain profiles in selected material location within the injection chamber and the curing die. Being the differences among the spectres transmitted and received are related to the variations in both temperature and strain, commercial FBG sensors were opportunely modified and calibrated. The optical fibers were hooked to the fibers entering into the injection pultrusion die. Taking the pulling speed into account, each waveform acquired was correlated to a position within the die. Obtained data highlight the effect of the heat generation due to resin reaction as well as longitudinal strains related to the pulling force, the thermal expansion and the chemical shrinkage of the resin system.

Simultaneous measurement of magnetic field and temperature based on an etched TCFMI cascaded with an FBG

NASA Astrophysics Data System (ADS)

Yan, Guofeng; Zhang, Liang; He, Sailing

2016-04-01

In this paper, a dual-parameter measurement scheme based on an etched thin core fiber modal interferometer (TCMI) cascaded with a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of magnetic field and temperature. The magnetic field and temperature responses of the packaged TCFMI were first investigated, which showed that the magnetic field sensitivity could be highly enhanced by decreasing of the TCF diameter and the temperature-cross sensitivities were up to 3-7 Oe/°C at 1550 nm. Then, the theoretical analysis and experimental demonstration of the proposed dual-parameter sensing scheme were conducted. Experimental results show that, the reflection of the FBG has a magnetic field intensity and temperature sensitivities of -0.017 dB/Oe and 0.133 dB/°C, respectively, while the Bragg wavelength of the FBG is insensitive to magnetic field and has a temperature sensitivity of 13.23 pm/°C. Thus by using the sensing matrix method, the intensity of the magnetic field and the temperature variance can be measured, which enables magnetic field sensing under strict temperature environments. In the on-off time response test, the fabricated sensor exhibited high repeatability and short response time of ∼19.4 s. Meanwhile the reflective sensing probe type is more compact and practical for applications in hard-to-reach conditions.

Micro-structured femtosecond laser assisted FBG hydrogen sensor.

PubMed

Karanja, Joseph Muna; Dai, Yutang; Zhou, Xian; Liu, Bin; Yang, Minghong

2015-11-30

We discuss hydrogen sensors based on fiber Bragg gratings (FBGs) micro-machined by femtosecond laser to form microgrooves and sputtered with Pd/Ag composite film. The atomic ratio of the two metals is controlled at Pd:Ag = 3:1. At room temperature, the hydrogen sensitivity of the sensor probe micro-machined by 75 mW laser power and sputtered with 520 nm of Pd/Ag film is 16.5 pm/%H. Comparably, the standard FBG hydrogen sensitivity becomes 2.5 pm/%H towards the same 4% hydrogen concentration. At an ambient temperature of 35°C, the processed sensor head has a dramatic rise in hydrogen sensitivity. Besides, the sensor shows good response and repeatability during hydrogen concentration test.

The perspective of the permanent monitoring with an FBG sensor network in oil and gas production in China

NASA Astrophysics Data System (ADS)

Zhang, Yuanzhong; Xiao, Lizhi; Fu, Jianwei; Chen, Haifeng; Zhao, Xiaoliang

2005-12-01

Most of the onshore oilfields in China are in the middle and late development stages, and great deals of residual oil are waiting for exploitation. Downhole permanent sensor monitoring technology is an effective means to enhance oil and gas recovery. The concept of the downhole permanent sensor network is introduced, and the research status was reviewed. The measurement principle, application and some issues of the Distribute Temperature System (DTS) and Fiber Bragg Grating (FBG) sensor are discussed. Some potential applications of permanent monitoring with FBG sensors in oil and gas production, including enhancing oil and gas recovery and realtime monitoring of casing damaging were reviewed.

MBM fuel feeding system design and evaluation for FBG pilot plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, William A., E-mail: bill.campbell@usask.ca; Fonstad, Terry; Pugsley, Todd

2012-06-15

Highlights: Black-Right-Pointing-Pointer A 1-5 g/s fuel feeding system for pilot scale FBG was designed, built and tested. Black-Right-Pointing-Pointer Multiple conveying stages improve pressure balancing, flow control and stability. Black-Right-Pointing-Pointer Secondary conveyor stage reduced output irregularity from 47% to 15%. Black-Right-Pointing-Pointer Pneumatic air sparging effective in dealing with poor flow ability of MBM powder. Black-Right-Pointing-Pointer Pneumatic injection port plugs with char at gasification temperature of 850 Degree-Sign C. - Abstract: A biomass fuel feeding system has been designed, constructed and evaluated for a fluidized bed gasifier (FBG) pilot plant at the University of Saskatchewan (Saskatoon, SK, Canada). The system was designedmore » for meat and bone meal (MBM) to be injected into the gasifier at a mass flow-rate range of 1-5 g/s. The designed system consists of two stages of screw conveyors, including a metering stage which controlled the flow-rate of fuel, a rotary airlock and an injection conveyor stage, which delivered that fuel at a consistent rate to the FBG. The rotary airlock which was placed between these conveyors, proved unable to maintain a pressure seal, thus the entire conveying system was sealed and pressurized. A pneumatic injection nozzle was also fabricated, tested and fitted to the end of the injection conveyor for direct injection and dispersal into the fluidized bed. The 150 mm metering screw conveyor was shown to effectively control the mass output rate of the system, across a fuel output range of 1-25 g/s, while the addition of the 50 mm injection screw conveyor reduced the irregularity (error) of the system output rate from 47% to 15%. Although material plugging was found to be an issue in the inlet hopper to the injection conveyor, the addition of air sparging ports and a system to pulse air into those ports was found to successfully eliminate this issue. The addition of the pneumatic injection

Astrocytes Specifically Remove Surface-Adsorbed Fibrinogen and Locally Express Chondroitin Sulfate Proteoglycans

PubMed Central

Hsiao, Tony W.; Swarup, Vimal P.; Kuberan, Balagurunathan; Tresco, Patrick A.; Hlady, Vladimir

2013-01-01

Surface-adsorbed fibrinogen (FBG) was recognized by adhering astrocytes and removed from the substrates in vitro by a two-phase removal process. The cells removed adsorbed FBG from binary proteins surface patterns (FBG + laminin, or FBG + albumin) while leaving the other protein behind. Astrocytes preferentially expressed chondroitin sulfate proteoglycan (CSPG) at the loci of fibrinogen stimuli; however no differences in overall CSPG production as a function of FBG surface coverage were identified. Removal of FBG by astrocytes was also found to be independent of transforming growth factor type β (TGF-β) receptor based signaling as cells maintained CSPG production in the presence of TGF-β receptor kinase inhibitor, SB 431542. The inhibitor decreased CSPG expression, but did not abolicsh it entirely. Because blood contact and subsequent FBG adsorption are unavoidable in neural implantations, the results indicate that implant-adsorbed FBG may contribute to reactive astrogliosis around the implant as astrocytes specifically recognize adsorbed FBG. PMID:23499985

Patterns of Adherence of Helicobacter pylori Clinical Isolates to Epithelial Cells, and its Association with Disease and with Virulence Factors.

PubMed

Vázquez-Jiménez, Flor Elizabeth; Torres, Javier; Flores-Luna, Lourdes; Cerezo, Silvia Giono; Camorlinga-Ponce, Margarita

2016-02-01

Adherence to the gastric epithelium is one of the most important steps of Helicobacter pylori to remain and cause disease. The aim of this study was to analyze whether H. pylori isolates from patients with different gastroduodenal diseases present differences in the pattern of adherence to gastric epithelial cells (AGS), in the ability to induce IL-8, and in the presence of virulence genes. We tested 75 H. pylori strains isolated from nonatrophic gastritis, gastric cancer, and duodenal ulcer patients. The adhesion pattern and IL-8 induction were determined in AGS cells, and invasion of AGS cells was studied using a gentamicin protection assay. The IL-8 levels induced were determined by ELISA. Helicobacter pylori strains presented diffuse adherence (DA) and localized (LA) adherence patterns, similar to those described for enteropathogenic E. coli (EPEC), were observed in AGS cells. A DA pattern was observed in 57% and LA in 43% of the strains, and DA was more frequent in isolates from patients with gastric cancer (p = 0.044). Strains with a LA pattern induced higher levels of IL-8 (p = 0.042) in AGS cells. The adherence pattern was not associated with neither invasiveness nor with the presence of virulence genes. Our study shows that H. pylori strains present adherence patterns to AGS cells resembling those observed in EPEC and that these patterns may be associated with disease and with activity on AGS cells. © 2015 John Wiley & Sons Ltd.

Comparative Analysis of Super-Shedder Strains of Escherichia coli O157:H7 Reveals Distinctive Genomic Features and a Strongly Aggregative Adherent Phenotype on Bovine Rectoanal Junction Squamous Epithelial Cells

PubMed Central

Cote, Rebecca; Katani, Robab; Moreau, Matthew R.; Kudva, Indira T.; Arthur, Terrance M.; DebRoy, Chitrita; Mwangi, Michael M.; Albert, Istvan; Raygoza Garay, Juan Antonio; Li, Lingling; Brandl, Maria T.; Carter, Michelle Q.; Kapur, Vivek

2015-01-01

Shiga toxin-producing Escherichia coli O157:H7 (O157) are significant foodborne pathogens and pose a serious threat to public health worldwide. The major reservoirs of O157 are asymptomatic cattle which harbor the organism in the terminal recto-anal junction (RAJ). Some colonized animals, referred to as “super-shedders” (SS), are known to shed O157 in exceptionally large numbers (>104 CFU/g of feces). Recent studies suggest that SS cattle play a major role in the prevalence and transmission of O157, but little is known about the molecular mechanisms associated with super-shedding. Whole genome sequence analysis of an SS O157 strain (SS17) revealed a genome of 5,523,849 bp chromosome with 5,430 open reading frames and two plasmids, pO157 and pSS17, of 94,645 bp and 37,446 bp, respectively. Comparative analyses showed that SS17 is clustered with spinach-associated O157 outbreak strains, and belongs to the lineage I/II, clade 8, D group, and genotype 1, a subgroup of O157 with predicted hyper-virulence. A large number of non-synonymous SNPs and other polymorphisms were identified in SS17 as compared with other O157 strains (EC4115, EDL933, Sakai, TW14359), including in key adherence- and virulence-related loci. Phenotypic analyses revealed a distinctive and strongly adherent aggregative phenotype of SS17 on bovine RAJ stratified squamous epithelial (RSE) cells that was conserved amongst other SS isolates. Molecular genetic and functional analyses of defined mutants of SS17 suggested that the strongly adherent aggregative phenotype amongst SS isolates is LEE-independent, and likely results from a novel mechanism. Taken together, our study provides a rational framework for investigating the molecular mechanisms associated with SS, and strong evidence that SS O157 isolates have distinctive features and use a LEE-independent mechanism for hyper-adherence to bovine rectal epithelial cells. PMID:25664460

Adherence of Lactobacillus crispatus to vaginal epithelial cells from women with or without a history of recurrent urinary tract infection.

PubMed

Kwok, Louisa; Stapleton, Ann E; Stamm, Walter E; Hillier, Sharon L; Wobbe, Cheryl L; Gupta, Kalpana

2006-11-01

Lactobacillus crispatus strain CTV-05 is a vaginal probiotic proposed for use in women with recurrent urinary tract infection to reduce vaginal colonization with Escherichia coli and the risk of urinary tract infection. However, the ability of this probiotic strain to adhere to the target mucosa, vaginal epithelial cells, has not been assessed in women with recurrent urinary tract infection. We measured the adherence of L. crispatus strain CTV-05 to vaginal epithelial cells collected from more than 100 premenopausal women with (cases) and without (controls) a history of recurrent urinary tract infection. We also examined the effects of relevant host factors on bacterial adherence. Bacterial adherence assays were performed by combining L. crispatus CTV-05 with exfoliated vaginal epithelial cells collected from 51 case women and 51 controls. L. crispatus CTV-05 adhered in high numbers to vaginal epithelial cells from women with recurrent urinary tract infection (mean adherence of 50.5 lactobacilli per vaginal epithelial cell) and controls (mean adherence of 39.4 lactobacilli per vaginal epithelial cell). Adherence was significantly higher using vaginal epithelial cells from women with a maternal history of urinary tract infection (p = 0.036) and a nonsecretor phenotype (p < 0.001), but was not significantly affected by recent spermicide use, oral contraceptive use, menstrual cycle phase or sexual activity. L. crispatus strain CTV-05 is highly adherent to vaginal epithelial cells collected from a large sample of premenopausal women with or without a history of recent recurrent urinary tract infection. These data strongly support further evaluation of this probiotic in clinical trials of women with recurrent urinary tract infection.

Discrete tuning concept for fiber-integrated lasers based on tailored FBG arrays and a theta cavity layout.

PubMed

Tiess, Tobias; Becker, Martin; Rothhardt, Manfred; Bartelt, Hartmut; Jäger, Matthias

2017-03-15

We demonstrate a novel tuning concept for pulsed fiber-integrated lasers with a fiber Bragg grating (FBG) array as a discrete and tailored spectral filter, as well as a modified laser design. Based on a theta cavity layout, the structural delay lines originating from the FBG array are balanced, enabling a constant repetition rate and stable pulse properties over the full tuning range. The emission wavelength is electrically tuned with respect to the filter properties based on an adapted temporal gating scheme using an acousto-optic modulator. This concept has been investigated with an Yb-doped fiber laser, demonstrating excellent emission properties with high signal contrast (>35  dB) and narrow linewidth (<150  pm) over a tuning range of 25 nm.

In Search of Multi-Peaked Reflective Spectrum with Optic Fiber Bragg Grating Sensor for Dynamic Strain Measurement

NASA Technical Reports Server (NTRS)

Tai, Hsiang

2006-01-01

In a typical optic fiber Bragg grating (FBG) strain measurement, unless in an ideal static laboratory environment, the presence of vibration or often disturbance always exists, which often creates spurious multiple peaks in the reflected spectrum, resulting in a non-unique determination of strain value. In this report we attempt to investigate the origin of this phenomenon by physical arguments and simple numerical simulation. We postulate that the fiber gratings execute small amplitude transverse vibrations changing the optical path in which the reflected light traverses slightly and non-uniformly. Ultimately, this causes the multi-peak reflected spectrum.

Distribution and Phylogeny of Immunoglobulin-Binding Protein G in Shiga Toxin-Producing Escherichia coli and Its Association with Adherence Phenotypes▿

PubMed Central

Merkel, Viktor; Ohder, Barbara; Bielaszewska, Martina; Zhang, Wenlan; Fruth, Angelika; Menge, Christian; Borrmann, Erika; Middendorf, Barbara; Müthing, Johannes; Karch, Helge; Mellmann, Alexander

2010-01-01

eibG in Shiga toxin-producing Escherichia coli (STEC) O91 encodes a protein (EibG) which binds human immunoglobulins G and A and contributes to bacterial chain-like adherence to human epithelial cells. We investigated the prevalence of eibG among STEC, the phylogeny of eibG, and eibG allelic variations and their impact on the adherence phenotype. eibG was found in 15.0% of 240 eae-negative STEC strains but in none of 157 eae-positive STEC strains. The 36 eibG-positive STEC strains belonged to 14 serotypes and to eight multilocus sequence types (STs), with serotype O91:H14/H− and ST33 being the most common. Sequences of the complete eibG gene (1,527 bp in size) from eibG-positive STEC resulted in 21 different alleles with 88.11% to 100% identity to the previously reported eibG sequence; they clustered into three eibG subtypes (eibG-α, eibG-β, and eibG-γ). Strains expressing EibG-α and EibG-β displayed a mostly typical chain-like adherence pattern (CLAP), with formation of long chains on both human and bovine intestinal epithelial cells, whereas strains with EibG-γ adhered in short chains, a pattern we termed atypical CLAP. The same adherence phenotypes were displayed by E. coli BL21(DE3) clones containing the respective eibG-α, eibG-β, and eibG-γ subtypes. We propose two possible evolutionary scenarios for eibG in STEC: a clonal development of eibG in strains with the same phylogenetic background or horizontal transfer of eibG between phylogenetically unrelated STEC strains. PMID:20547747

Escherichia coli isolated from a Crohn's disease patient adheres, invades, and induces inflammatory responses in polarized intestinal epithelial cells.

PubMed

Eaves-Pyles, Tonyia; Allen, Christopher A; Taormina, Joanna; Swidsinski, Alexander; Tutt, Christopher B; Jezek, G Eric; Islas-Islas, Martha; Torres, Alfredo G

2008-07-01

Inflammatory diseases of the intestinal tract are a major health concern both in the United States and around the world. Evidence now suggests that a new category of Escherichia coli, designated Adherent Invasive E. coli (AIEC) is highly prevalent in Crohn's Disease (CD) patients. AIEC strains have been shown to colonize and adhere to intestinal epithelial cells (IEC). However, the role AIEC strains play in the induction of an inflammatory response is not known. Therefore, we examined several E. coli strains (designated LF82, O83:H1, 6604 and 6655) that were isolated from CD patients for their ability to induce inflammation in two IEC, Caco-2BBe and T-84 cells. Results showed that each strain had varying abilities to adhere to and invade IEC as well as induced cytokine secretion from polarized IEC. However, E. coli O83:H1 displayed the best characteristics of AIEC strains as compared to the prototype AIEC strain LF82, inducing cytokine secretion from IEC and promoting immune cell migration through IEC. Upon further analysis, E. coli O83:H1 did not harbor virulence genes present in known pathogenic intestinal organisms. Further characterization of E. coli O83:H1 virulence determinants showed that a non-flagellated O83:H1 strain significantly decreased the organism's ability to adhere to and invade both IEC and elicit IEC cytokine secretion compared to the wild type and complemented strains. These findings demonstrate that E. coli O83:H1 possesses the characteristics of the AIEC LF82 strain that may contribute to the low-grade, chronic inflammation observed in Crohn's disease.

MBM fuel feeding system design and evaluation for FBG pilot plant.

PubMed

Campbell, William A; Fonstad, Terry; Pugsley, Todd; Gerspacher, Regan

2012-06-01

A biomass fuel feeding system has been designed, constructed and evaluated for a fluidized bed gasifier (FBG) pilot plant at the University of Saskatchewan (Saskatoon, SK, Canada). The system was designed for meat and bone meal (MBM) to be injected into the gasifier at a mass flow-rate range of 1-5 g/s. The designed system consists of two stages of screw conveyors, including a metering stage which controlled the flow-rate of fuel, a rotary airlock and an injection conveyor stage, which delivered that fuel at a consistent rate to the FBG. The rotary airlock which was placed between these conveyors, proved unable to maintain a pressure seal, thus the entire conveying system was sealed and pressurized. A pneumatic injection nozzle was also fabricated, tested and fitted to the end of the injection conveyor for direct injection and dispersal into the fluidized bed. The 150 mm metering screw conveyor was shown to effectively control the mass output rate of the system, across a fuel output range of 1-25 g/s, while the addition of the 50mm injection screw conveyor reduced the irregularity (error) of the system output rate from 47% to 15%. Although material plugging was found to be an issue in the inlet hopper to the injection conveyor, the addition of air sparging ports and a system to pulse air into those ports was found to successfully eliminate this issue. The addition of the pneumatic injection nozzle reduced the output irregularity further to 13%, with an air supply of 50 slpm as the minimum air supply to drive this injector. After commissioning of this final system to the FBG reactor, the injection nozzle was found to plug with char however, and was subsequently removed from the system. Final operation of the reactor continues satisfactorily with the two screw conveyors operating at matching pressure with the fluidized bed, with the output rate of the system estimated based on system characteristic equations, and confirmed by static weight measurements made before

Monitoring Concrete Deterioration Due to Reinforcement Corrosion by Integrating Acoustic Emission and FBG Strain Measurements

PubMed Central

Li, Weijie; Xu, Changhang; Ho, Siu Chun Michael; Wang, Bo; Song, Gangbing

2017-01-01

Corrosion of concrete reinforcement members has been recognized as a predominant structural deterioration mechanism for steel reinforced concrete structures. Many corrosion detection techniques have been developed for reinforced concrete structures, but a dependable one is more than desired. Acoustic emission technique and fiber optic sensing have emerged as new tools in the field of structural health monitoring. In this paper, we present the results of an experimental investigation on corrosion monitoring of a steel reinforced mortar block through combined acoustic emission and fiber Bragg grating strain measurement. Constant current was applied to the mortar block in order to induce accelerated corrosion. The monitoring process has two aspects: corrosion initiation and crack propagation. Propagation of cracks can be captured through corresponding acoustic emission whereas the mortar expansion due to the generation of corrosion products will be monitored by fiber Bragg grating strain sensors. The results demonstrate that the acoustic emission sources comes from three different types, namely, evolution of hydrogen bubbles, generation of corrosion products and crack propagation. Their corresponding properties are also discussed. The results also show a good correlation between acoustic emission activity and expansive strain measured on the specimen surface. PMID:28327510

Monitoring Concrete Deterioration Due to Reinforcement Corrosion by Integrating Acoustic Emission and FBG Strain Measurements.

PubMed

Li, Weijie; Xu, Changhang; Ho, Siu Chun Michael; Wang, Bo; Song, Gangbing

2017-03-22

Corrosion of concrete reinforcement members has been recognized as a predominant structural deterioration mechanism for steel reinforced concrete structures. Many corrosion detection techniques have been developed for reinforced concrete structures, but a dependable one is more than desired. Acoustic emission technique and fiber optic sensing have emerged as new tools in the field of structural health monitoring. In this paper, we present the results of an experimental investigation on corrosion monitoring of a steel reinforced mortar block through combined acoustic emission and fiber Bragg grating strain measurement. Constant current was applied to the mortar block in order to induce accelerated corrosion. The monitoring process has two aspects: corrosion initiation and crack propagation. Propagation of cracks can be captured through corresponding acoustic emission whereas the mortar expansion due to the generation of corrosion products will be monitored by fiber Bragg grating strain sensors. The results demonstrate that the acoustic emission sources comes from three different types, namely, evolution of hydrogen bubbles, generation of corrosion products and crack propagation. Their corresponding properties are also discussed. The results also show a good correlation between acoustic emission activity and expansive strain measured on the specimen surface.

Liquid level and temperature sensing by using dual-wavelength fiber laser based on multimode interferometer and FBG in parallel

NASA Astrophysics Data System (ADS)

Sun, Chunran; Dong, Yue; Wang, Muguang; Jian, Shuisheng

2018-03-01

The detection of liquid level and temperature based on a fiber ring cavity laser sensing configuration is presented and demonstrated experimentally. The sensing head contains a fiber Bragg grating (FBG) and a single-mode-cladding-less-single-mode multimode interferometer, which also functions as wavelength-selective components of the fiber laser. When the liquid level or temperature is applied on the sensing head, the pass-band peaks of both multimode interference (MMI) filter and FBG filter vary and the two output wavelengths of the laser shift correspondingly. In the experiment, the corresponding sensitivities of the liquid level with four different refractive indices (RI) in the deep range from 0 mm to 40 mm are obtained and the sensitivity enhances with the RI of the liquid being measured. The maximum sensitivity of interferometer is 106.3 pm/mm with the RI of 1.391. For the temperature measurement, a sensitivity of 10.3 pm/°C and 13.8 pm/°C are achieved with the temperature ranging from 0 °C to 90 °C corresponding to the two lasing wavelengths selective by the MMI filter and FBG, respectively. In addition, the average RI sensitivity of 155.77 pm/mm/RIU is also obtained in the RI range of 1.333-1.391.

Adherence and drug resistance: predictions for therapy outcome.

PubMed Central

Wahl, L M; Nowak, M A

2000-01-01

We combine standard pharmacokinetics with an established model of viral replication to predict the outcome of therapy as a function of adherence to the drug regimen. We consider two types of treatment failure: failure to eliminate the wild-type virus, and the emergence of drug-resistant virus. Specifically, we determine the conditions under which resistance dominates as a result of imperfect adherence. We derive this result for both single- and triple-drug therapies, with attention to conditions which favour the emergence of viral strains that are resistant to one or more drugs in a cocktail. Our analysis provides quantitative estimates of the degree of adherence necessary to prevent resistance. We derive results specific to the treatment of human immunodeficiency virus infection, but emphasize that our method is applicable to a range of viral or other infections treated by chemotherapy. PMID:10819155

Quasi-distributed fiber sensor using active mode locking laser cavity with multiple FBG reflections

NASA Astrophysics Data System (ADS)

Park, Chang Hyun; Kim, Gyeong Hun; Kim, Chang-Seok; Lee, Hwi Don; Chung, Youngjoo

2017-04-01

We have demonstrated a quasi-distributed sensor using an active mode-locking (AML) laser with multiple fiber Bragg grating (FBG) reflections of the same center wavelength. We found that variations in the multiple cavity segment lengths between FBGs can be measured by simply sweeping the modulation frequency, because the modulation frequency of the AML laser is proportionally affected by cavity length.

Packaged FBG sensors for real-time stress monitoring on deep-water riser

NASA Astrophysics Data System (ADS)

Xu, Jian; Yang, Dexing; Jiang, Yajun; Wang, Meirong; Zhai, Huailun; Bai, Yang

2014-11-01

The safety of under-water risers in drilling platform is of great significance. A packaged fiber Bragg grating (FBG) sensor for real-time stress monitoring is designed for the applications on oil drilling risers under 3000 meters deep water. A copper tube which is the main component of the sensor has a small hole along its axes and a groove at its each end. The bare FBG is passed through the small hole and fixed to its ends by epoxy resin. Then the copper tube is packaged by filling the groove with structural adhesive. In order to avoid that the outer water-pressure is applied on the epoxy resin through the structural adhesive, a gap between the two types of glues is left. The relationships between the stress of the riser and the tension, pressure, temperature of the single sensor are discussed, respectively. The measured tension sensitivity is 136.75 pm/KN while the minimum R-square value is 0.99997. The experimental results also show that there is a good linear response between water-pressure and the Bragg wavelength from 0 to 30MPa, and the sensor can even survive under the pressure more than 30MPa. In addition, the Bragg wavelength shifts linearly with the increasing temperature from 0 to 40°C. So, the pressure and temperature can be easily compensated if another sensor without tension is used.

Broadband FBG resonator seismometer: principle, key technique, self-noise, and seismic response analysis.

PubMed

Huang, Wenzhu; Zhang, Wentao; Luo, Yingbo; Li, Li; Liu, Wenyi; Li, Fang

2018-04-16

A broadband optical fiber seismometer based on FBG resonator is proposed for earthquake monitoring. The principle and key technique, high-resolution ultralow-frequency wavelength interrogation by dual-laser swept frequency and beat frequency method, are discussed and analyzed. From the simulation and test results, the seismometer works at broadband range from 0.01 Hz to 10 Hz with a sensitivity of better than 330 pm/g and the wavelength resolution of the interrogation system is better than 0.001 pm/√Hz from 0.1 Hz to 10 Hz. A three-channel correlation method is used to measure the self-noise of the seismometer. It reaches a noise level of 2.7 × 10 -7 ms -2 /√Hz@0.1 Hz, which is lower than the earth's background noise (the new high noise model, NHNM). An earthquake monitoring experiment is conducted in a low noise seismic station. The recorded seismic waves are analyzed, which suggests that the proposed seismometer has the ability to record the close microearthquake and distant great earthquake with a high signal-noise ratio (SNR). This is the first time that a FBG-based middle-long period seismometer with lower self-noise than NHNM and large dynamic range (100 dB) is reported.

Strain measurements by fiber Bragg grating sensors for in situ pile loading tests

NASA Astrophysics Data System (ADS)

Schmidt-Hattenberger, Cornelia; Straub, Tilmann; Naumann, Marcel; Borm, Günter; Lauerer, Robert; Beck, Christoph; Schwarz, Wolfgang

2003-07-01

A fiber Bragg grating (FBG) sensor network has been installed into a large diameter concrete pile on a real construction site. The intention was to monitor its deformation behavior during several quasi-static loading cycles. The skin friction between pile and subsoil affecting the ultimate bearing capacity of the pile as well as the settlement behavior of the structure under investigation has been derived from our measurements. A comparison between the results of the fiber Bragg grating sensors and conventional concrete strain gages (CSG) has shown excellent correspondence.

Flagellar Cap Protein FliD Mediates Adherence of Atypical Enteropathogenic Escherichia coli to Enterocyte Microvilli

PubMed Central

Sampaio, Suely C. F.; Luiz, Wilson B.; Vieira, Mônica A. M.; Ferreira, Rita C. C.; Garcia, Bruna G.; Sinigaglia-Coimbra, Rita; Sampaio, Jorge L. M.; Ferreira, Luís C. S.

2016-01-01

The expression of flagella correlates with different aspects of bacterial pathogenicity, ranging from adherence to host cells to activation of inflammatory responses by the innate immune system. In the present study, we investigated the role of flagella in the adherence of an atypical enteropathogenic Escherichia coli (aEPEC) strain (serotype O51:H40) to human enterocytes. Accordingly, isogenic mutants deficient in flagellin (FliC), the flagellar structural subunit; the flagellar cap protein (FliD); or the MotAB proteins, involved in the control of flagellar motion, were generated and tested for binding to differentiated Caco-2 cells. Binding of the aEPEC strain to enterocytes was significantly impaired in strains with the fliC and fliD genes deleted, both of which could not form flagella on the bacterial surface. A nonmotile but flagellated MotAB mutant also showed impaired adhesion to Caco-2 cells. In accordance with these observations, adhesion of aEPEC strain 1711-4 to Caco-2 cells was drastically reduced after the treatment of Caco-2 cells with purified FliD. In addition, incubation of aEPEC bacteria with specific anti-FliD serum impaired binding to Caco-2 cells. Finally, incubation of Caco-2 cells with purified FliD, followed by immunolabeling, showed that the protein was specifically bound to the microvillus tips of differentiated Caco-2 cells. The aEPEC FliD or anti-FliD serum also reduced the adherence of prototype typical enteropathogenic, enterohemorrhagic, and enterotoxigenic E. coli strains to Caco-2 cells. In conclusion, our findings further strengthened the role of flagella in the adherence of aEPEC to human enterocytes and disclosed the relevant structural and functional involvement of FliD in the adhesion process. PMID:26831466

Impact localization on composite laminates using fiber Bragg grating sensors and a novel technique based on strain amplitude

NASA Astrophysics Data System (ADS)

Zhao, Gang; Li, Shuxin; Hu, Haixiao; Zhong, Yucheng; Li, Kun

2018-01-01

Carbon fiber reinforced composite materials have been widely used in aerospace and other high-tech fields because of their excellent performance. However barely visible impact damage can be introduced by low velocity impact, which might bring out tremendous risk. In this paper, a new method is proposed to predict the position of low velocity impact. The dynamic strain signal that is caused by low velocity impact is obtained by the fiber Bragg grating (FBG) sensor. The amplitude of the first K order natural frequency is extracted by Fast Fourier Transform (FFT). The amplitude data is normalized, and then establish k order vector matrix model is established. It is proposed that K order sum of squares of deviations can be used as the basis to predict positioning. Two different validation tests were performed. The experimental model was made of different layers. FBG were used to embed and paste type method, experiments were conducted with impact of different energy levels. The results show that proposed method is feasible.

Design and performance evaluation of a dispersion compensation unit using several chirping functions in a tanh apodized FBG and comparison with dispersion compensation fiber.

PubMed

Mohammed, Nazmi A; Solaiman, Mohammad; Aly, Moustafa H

2014-10-10

In this work, various dispersion compensation methods are designed and evaluated to search for a cost-effective technique with remarkable dispersion compensation and a good pulse shape. The techniques consist of different chirp functions applied to a tanh fiber Bragg grating (FBG), a dispersion compensation fiber (DCF), and a DCF merged with an optimized linearly chirped tanh FBG (joint technique). The techniques are evaluated using a standard 10 Gb/s optical link over a 100 km long haul. The linear chirp function is the most appropriate choice of chirping function, with a pulse width reduction percentage (PWRP) of 75.15%, lower price, and poor pulse shape. The DCF yields an enhanced PWRP of 93.34% with a better pulse quality; however, it is the most costly of the evaluated techniques. Finally, the joint technique achieved the optimum PWRP (96.36%) among all the evaluated techniques and exhibited a remarkable pulse shape; it is less costly than the DCF, but more expensive than the chirped tanh FBG.

Methodology optimization and diversification for the investigation of virulence potential in Haemophilus influenzae clinical strains.

PubMed

Giucă, Mihaela Cristina; Străuţ, Monica; Surdeanu, Maria; Nica, Maria; Ungureanu, Vasilica; Mihăescu, Grigore

2011-01-01

Ten Haemophilus influenzae strains were isolated from patients aged between 1.6 - 24 years, with various diagnoses (acute meningitis, acute upper respiratory infection, otitis media and acute sinusitis). Identification was based on phenotypic and molecular characteristics; antibiotic susceptibility testing was performed by diffusion method according to CLSI standards 2011 for seven antibiotics. The results of molecular testing showed that all the studied strains produced an amplicon of 1000 bp with ompP2 primers indicating that all strains were H. influenzae. For six strains, the PCR amplicon obtained with bexA specific primers, proving that the strains were capsulated. The results of phenotypic testing showed that four strains were ampicillin nonsusceptible and (beta-lactamase-positive. The virulence potential of H. influenzae clinical strains was investigated by phenotypic methods, including the assessment of the soluble virulence factors on specific media containing the biochemical substratum for the investigated enzymatic factor, as well as the adherence and invasion capacity to HeLa cells monolayer using Cravioto modified method. The studied strains exhibited mainly a diffuse adherence pattern and different adherence indexes. Interestingly, two strains isolated from the same pacient (blood and CSF) showed a different degree of invasiveness, the strain isolated from blood being 20 times more invasive than the one isolated from CSF.

A civil structural monitoring system based on fiber grating sensors

NASA Astrophysics Data System (ADS)

Zhang, Yan; Cai, Haiwen; Pastore, Robert; Ju, Jing; Zeng, Debing; Yin, Zhifan; Cui, Hong-Liang

2003-08-01

Optical fiber sensors based on Fiber Bragg Grating (FBG) technology have found many applications in the area of civil structural monitoring systems, such as in bridge monitoring and maintenance. FBG sensors can measure the deformation, overload and cracks on bridge with a high sensitivity. In this paper we report on our recent work a structural monitoring system using FBG sensors. Basic theoretical background and design of the system is described here, including the light source, FBG sensors, demodulator sensors, signal detection and processing schemes. The system will be installed on a major arch bridge currently under construction in Shanghai, China for long-term in situ health monitoring. The system schematic arrangement on the bridge is introduced in brief. Simulation experiments in the laboratory were carried out to test the performance of FBG strain sensors. The sensor response shows excellent linearity against the strain imposed on it. Traffic and overload monitoring on bridge using FBG sensors is also discussed and planned for the near future.

Intelligent Multi-scale Sensors for Damage Identification and Mitigation in Woven Composites for Aerospace Structural Applications

DTIC Science & Technology

2012-08-15

Bragg grating ( FBG ) sensors within these composite structures allows one to correlate sensor response features to “critical damage events” within the...material. The unique capabilities of this identification strategy are due to the detailed information obtained from the FBG sensors and the... FBG sensors relate to damage states not merely strain amplitudes. The research objectives of this project were therefore to:  demonstrate FBG

Research on a novel composite structure Er³⁺-doped DBR fiber laser with a π-phase shifted FBG.

PubMed

Zhao, Yanjie; Chang, Jun; Wang, Qingpu; Ni, Jiasheng; Song, Zhiqiang; Qi, Haifeng; Wang, Chang; Wang, Pengpeng; Gao, Liang; Sun, Zhihui; Lv, Guangping; Liu, Tongyu; Peng, Gangding

2013-09-23

A simple composite cavity structure Er³⁺-doped fiber laser was proposed and demonstrated experimentally. The resonant cavity consists of a pair of uniform fiber Bragg gratings (FBGs) and a π-phase shifted FBG. By introducing the π-phase shifted FBG into the cavity as the selective wavelength component, it can increase the effective length of the laser cavity and suppress the multi-longitudinal modes simultaneously. The narrow linewidth of 900 Hz and low RIN of -95 dB/Hz were obtained. And the lasing wavelength was rather stable with the pump power changing. The SMRS was more than 67 dB. The results show that the proposed fiber laser has a good performance and considerable potential application for fiber sensor and optical communication.

Bacterial Population Adherent to the Epithelium on the Roo of the Dorsal Rumen of Sheep †

PubMed Central

Dehority, Burk A.; Grubb, Jean A.

1981-01-01

By anaerobic procedures, the total number of adherent bacteria was determined on tissue samples obtained from the roof of the dorsal rumen of three sheep. After four washings, 1.91 × 107, 0.34 × 107, and 1.23 × 107 bacteria per cm2 were still attached to the rumen epithelium in sheep 1, 2, and 3, respectively. A total of 95 strains of bacteria were isolated from these three samples. Based on morphology, Gram stain, anaerobiosis, motility, and fermentation end products, they were presumptively identified as follows: Butyrivibrio fibrisolvens, 30 strains; atypical Butyrivibrio, 5 strains; Bacteroides ruminicola, 22 strains; Lactobacillus, 1 strain; and unknown Bacteroides species, 37 strains. For sheep 3, washing the rumen epithelium a total of 10 times reduced the adherent bacterial population by 93% (8.4 × 105 bacteria per cm2). Of 30 strains isolated from this sample, 22 were presumptively identified as Butyrivibrio and Bacteroides types. These results suggest that the epithelium on the roof of the dorsal rumen is primarily colonized by two genera of bacteria, Butyrivibrio and Bacteroides. Most Butyrivibrio and Bacteroides ruminicola strains appeared to be similar to previously isolated rumen strains. However, the unknown Bacteroides species differed considerably from the three species of this genus which are commonly isolated from rumen contents. PMID:16345797

Design of Novel FBG-Based Sensor of Differential Pressure with Magnetic Transfer.

PubMed

Lyu, Guohui; Che, Guohang; Li, Junqing; Jiang, Xu; Wang, Keda; Han, Yueqiang; Gao, Laixu

2017-02-15

In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements.

Finite element modeling to determine thermal residual strain distribution of bonded composite repairs for structural health monitoring design

NASA Astrophysics Data System (ADS)

Baker, Wayne; Jones, Rhys; Davis, Claire; Galea, Stephen C.

2002-11-01

The economic implication of fleet upgrades, particularly in Australia with military aircraft such as the F-111 and F/A-18, has led to an increasing reliance on composite repair technology to address fatigue and corrosion-affected aircraft components. The increasing use of such repairs has led to a research effort to develop various in-situ health monitoring systems that may be incorporated with a repair. This paper reports on the development of a theoretical methodology that uses finite element analysis (FEA) to model the strain profiles which optical sensors, on or within the patch, will be exposed to under various operational scenarios, including load and disbond. Numerical techniques are then used to predict the fibre Bragg grating (FBG) reflections which occur with these strain profiles. The quality of these reflection are a key consideration when designing FBG based structural health monitoring (SHM) systems. This information can be used to optimise the location of both surface mounted, and embedded sensors, and determine feasibility of SHM system design. Research was conducted into the thermal residual strain (TRS) within the patch. A finite element study revealed the presence of significant thermal residual strain gradients along the surface of the tapered region of the patch. As Bragg gratings are particularly sensitive to strain gradients, (producing a result similar to a chirped grating) the strain gradient on the composite at potential sensor locations both under load, and in the event of disbond was considered. A sufficiently high gradient leads to an altered Bragg reflection. These spurious reflections need to be considered, and theoretically obtained reflections can provide information to allow for load scenarios where the Bragg shift is not a smooth, well defined peak. It can also be shown that embedded fibres offer a higher average thermal residual strain reading, while being subject to a much lower strain gradient. This particularly favors the

Pharmacists’ perspectives on promoting medication adherence among patients with HIV

PubMed Central

Kibicho, Jennifer W.; Owczarzak, Jill

2015-01-01

Objectives To provide pharmacists’ perspectives on medication adherence barriers for patients with human immunodeficiency virus (HIV) and to describe pharmacists’ strategies for promoting adherence to antiretroviral medications. Design Multisite, qualitative, descriptive study. Setting Four midwestern U.S. states, from August through October 2009. Participants 19 pharmacists at 10 pharmacies providing services to patients with HIV. Intervention Pharmacists were interviewed using a semistructured interview guide. Main outcome measures Barriers to medication adherence, pharmacist interventions, challenges to promoting adherence. Results Pharmacists reported a range of adherence barriers that were patient specific (e.g., cognitive factors, lack of social support), therapy related (e.g., adverse effects, intolerable medications), and structural level (e.g., strained provider relationships). They used a combination of individually tailored, patient-specific interventions that identified and resolved adherence barriers and actively anticipated and addressed potential adherence barriers. Pharmacist interventions included medication-specific education to enhance patient self-efficacy, follow-up calls to monitor adherence, practical and social support to motivate adherence, and patient referrals to other health care providers. However, the pharmacists faced internal (e.g., lack of time, lack of trained personnel) and external (e.g., insurance policies that disallowed patient enrollment in automatic prescription refill program) challenges. Conclusion Pharmacists in community settings went beyond prescription drug counseling mandated by law to provide additional pharmacy services that were tailored to the needs of patients with HIV. Given that many individuals with HIV are living longer, more research is needed on the effectiveness and cost effectiveness of pharmacists’ interventions in clinical practice, in order to inform insurance reimbursement policies. PMID

First Deminsys (high speed FBG interrogator) flight

NASA Astrophysics Data System (ADS)

van Els, Thomas J.

2009-03-01

Deminsys is the world's fastest multi sensor / multi channel FBG interrogator, identifies one till four channels with typically 8 sensors per channel. The system is especially developed for the interrogation of signals up to 19,3 kHz for each sensor and the sample frequency is independent of the number of sensors. By having multiple sensors per fibre you can create a very compact network of sensors. Due to its revolutionary (light weight, compact and solid state) design, Deminsys seems to fit perfectly into (research) programs for aerospace, medic & life science, maritime, industrial, crash test and all other fast detection applications. Technobis Fibre Technologies (TFT) and NLR made a first test flight with the Deminsys optical fibre measurement system using the NLR test aircraft on October 24th 2008. This flight was a first step in the further development of the current system in order to make it suitable for operation on-board an aircraft and bring it from TRL3 towards TRL5, a functional model for aerospace applications.

Cyto-adherence of Mycoplasma mycoides subsp. mycoides to bovine lung epithelial cells.

PubMed

Aye, Racheal; Mwirigi, Martin Kiogora; Frey, Joachim; Pilo, Paola; Jores, Joerg; Naessens, Jan

2015-02-07

Mycoplasma mycoides subsp. mycoides (Mmm) is the causative agent of contagious bovine pleuropneumonia (CBPP), a respiratory disease of cattle, whereas the closely related Mycoplasma mycoides subsp. capri (Mmc) is a goat pathogen. Cyto-adherence is a crucial step in host colonization by mycoplasmas and subsequent pathogenesis. The aim of this study was to investigate the interactions between Mmm and mammalian host cells by establishing a cyto-adherence flow cytometric assay and comparing tissue and species specificity of Mmm and Mmc strains. There were little significant differences in the adherence patterns of eight different Mmm strains to adult bovine lung epithelial cells. However, there was statistically significant variation in binding to different host cells types. Highest binding was observed with lung epithelial cells, intermediate binding with endothelial cells and very low binding with fibroblasts, suggesting the presence of effective adherence of Mmm on cells lining the airways of the lung, which is the target organ for this pathogen, possibly by high expression of a specific receptor. However, binding to bovine fetal lung epithelial cells was comparably low; suggesting that the lack of severe pulmonary disease seen in many infected young calves can be explained by reduced expression of a specific receptor. Mmm bound with high efficiency to adult bovine lung cells and less efficiently to calves or goat lung cells. The data show that cyto-adherence of Mmm is species- and tissue- specific confirming its role in colonization of the target host and subsequent infection and development of CBPP.

Effect of decrease in both postprandial blood glucose (PBG) and fasting blood glucose (FBG) levels in normal beagle dogs with nateglinide enteric coated granules and immediate release tablets.

PubMed

Makino, Chisato; Ninomiya, Nobutaka; Sakai, Hidetoshi; Orita, Haruo; Okano, Akira; Yabuki, Akira

2006-04-01

Nateglinide is a new quick action/short duration (QRSD) type of oral blood glucose regulator, and nateglinide immediate release tablets are used for patients with mild diabetes under the trade name of Fastic((R)) tablets. In this study, we attempted to determine if it was possible to control both post-prandial blood glucose level (PBG) and fasting blood glucose level (FBG) for moderate or severe diabetes through controlled release of nateglinide. Enteric coated granules were selected for the administration form for controlled release of nateglinide, and three types of enteric coated granules were prepared having dissolution pH values of 5.5, 6.5 and 7.2. The three types of enteric coated granules were each administered separately or the enteric coated granules having an dissolution pH of 6.5 were administered simultaneous to administration of nateglinide immediate release tablets to normal beagle dogs just before feeding followed by measurement of plasma nateglinide concentration, plasma insulin concentration and blood glucose level. In the case of administering enteric coated granules alone (nateglinide: 9 mg/kg), the absorption of nateglinide was confirmed to tend to be delayed as the dissolution pH increased. In the case of an dissolution pH of 5.5, decreases in both PBG and FBG were observed. In the case of dissolution pH values of 6.5 and 7.2, only decrease in FBG was observed. In case of nateglinide immediate release tablets (nateglinide: 9 mg/kg), only decrease in PBG was observed. Decreases in both PBG and FBG were observed in the case of simultaneous administration of dissolution pH 6.5 enteric coated granules and nateglinide immediate release tablets just before feeding (nateglinide: 90 mg/head+60 mg/head). A correlation was observed between plasma nateglinide concentrations and blood glucose levels. On the other hand, there were no correlations observed between changes in plasma insulin concentrations and blood glucose levels. In case of nateglinide

Experimental Investigation on Acousto-Ultrasonic Sensing Using Polarization-Maintaining Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Wang, Gang; Banks, Curtis E.

2015-01-01

This report discusses the guided Lamb wave sensing using polarization-maintaining (PM) fiber Bragg grating (PM-FBG) sensor. The goal is to apply the PM-FBG sensor system to composite structural health monitoring (SHM) applications in order to realize directivity and multi-axis strain sensing capabilities while using reduced number of sensors. Comprehensive experiments were conducted to evaluate the performance of the PM-FBG sensor in a composite panel structure under different actuation frequencies and locations. Three Macro-Fiber-Composite (MFC) piezoelectric actuators were used to generate guided Lamb waves and they are oriented at 0, 45, and 90 degrees with respect to PM-FBG axial direction, respectively. The actuation frequency was varied from 20kHz to 200kHz. It is shown that the PM-FBG sensor system is able to detect high-speed ultrasound waves and capture the characteristics under different actuation conditions. Both longitudinal and lateral strain components in the order of nano-strain were determined based on the reflective intensity measurement data from fast and slow axis of the PM fiber. It must be emphasized that this is the first attempt to investigate acousto-ultrasonic sensing using PM-FBG sensor. This could lead to a new sensing approach in the SHM applications.

Experimental Investigation on Acousto-ultrasonic Sensing Using Polarization-Maintaining Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Wang, Gag; Banks, Curtis E.

2016-01-01

This report discusses the guided Lamb wave sensing using polarization-maintaining (PM) fiber Bragg grating (PM-FBG) sensor. The goal is to apply the PM-FBG sensor system to composite structural health monitoring (SHM) applications in order to realize directivity and multi-axis strain sensing capabilities while reducing the number of sensors. Comprehensive experiments were conducted to evaluate the performance of the PM-FBG sensor attached to a composite panel structure under different actuation frequencies and locations. Three Macro-Fiber-Composite (MFC) piezoelectric actuators were used to generate guided Lamb waves that were oriented at 0, 45, and 90 degrees with respect to PM-FBG axial direction, respectively. The actuation frequency was varied from 20kHz to 200kHz. It was shown that the PM-FBG sensor system was able to detect high-speed ultrasound waves and capture the characteristics under different actuation conditions. Both longitudinal and lateral strain components in the order of nano-strain were determined based on the reflective intensity measurement data from fast and slow axis of the PM fiber. It must be emphasized that this is the first attempt to investigate acouto-ultrasonic sensing using PM-FBG sensor. This could lead to a new sensing approach in the SHM applications. Nomenclature.

The Packaging Technology Study on Smart Composite Structure Based on The Embedded FBG Sensor

NASA Astrophysics Data System (ADS)

Zhang, Youhong; Chang, Xinlong; Zhang, Xiaojun; He, Xiangyong

2018-03-01

It is convenient to carry out the health monitoring of the solid rocket engine composite shell based on the embedded FBG sensor. In this paper, the packaging technology using one-way fiber layer of prepreg fiberglass/epoxy resin was proposed. The proposed packaging process is simple, and the packaged sensor structure size is flexible and convenient to use, at the mean time, the packaged structure has little effect on the pristine composite material structure.

Virulence characteristics of Escherichia coli strains causing asymptomatic bacteriuria.

PubMed

Vranes, J; Kruzić, V; Sterk-Kuzmanović, N; Schönwald, S

2003-08-01

The objective of this study was to examine the expression of Escherichia coli virulence-associated factors among the strains isolated from a group of women with a history of recurrent urinary tract infections (UTIs), in whom asymptomatic bacteriuria (ABU) was detected at follow-up, and from a group of children without a history of previous UTI, in whom ABU was detected during the screening. Possible differences between the virulence potential of these strains were investigated. Hemolysin production, the ability to adhere to Buffalo green monkey cell line and hemagglutination (HA) ability of the ABU-associated E. coli strains were tested. E. coli strains isolated from patients with acute recurrent UTIs served as a comparison. The well-known low virulence of strains isolated from patients with ABU was demonstrated. In contrast to strains isolated from recurrent uncomplicated UTIs, the ABU-associated strains were mostly nonhemolytic (75%), nonadherent (70%) and lacked HA ability (61%). HA ability was significantly more common among the strains isolated from children without a history of UTI than among the strains isolated from women with recurrent UTIs (chi2 = 9.97, p < 0.01), whereas the adherence and hemolytic abilities did not differ between the two ABU groups. A further prospective study is needed to determine whether the HA ability is the predictor of subsequent symptomatic UTI.

Strain measurement using a Brillouin optical time domain reflectometer for development of aircraft structure health monitoring system

NASA Astrophysics Data System (ADS)

Shimizu, Takayuki; Yari, Takashi; Nagai, Kanehiro; Takeda, Nobuo

2001-07-01

We conducted theoretical and experimental approaches for applying Brillouin optical time domain reflectometer (BOTDR) to aircraft and spacecraft structure health monitoring system. Firstly, distributed strain was measured by BOTDR under 3-point bending test and a spatial resolution was enhanced up to 0.5m using Brillouin spectrum analysis and processing though the device used in this experiment had a spatial resolution of 2m normally. Secondly, dynamic strain measurement was executed under cyclic loading conditions. Brillouin spectrum measured under dynamic conditions is equivalent to superposed spectrum using many spectra measured under static loading conditions. As the measured spectrum was decomposed into many spectra in static loading state, the strain amplitude and its ratio could be estimated. Thirdly, strain and temperature could be measured independently using combined system of BOTDR and fiber Bragg grating (FBG) with wavelength division multiplexing (WDM). Additionally, the application of BOTDR sensing system was shown for a prototype carbon fiber reinforced plastic (CFRP) liquid hydrogen (LH2) tank under cryogenic condition.

Role of commercial probiotic strains against human pathogen adhesion to intestinal mucus.

PubMed

Collado, M C; Meriluoto, J; Salminen, S

2007-10-01

The aims of this study present were to assess and to evaluate in vitro the abilities of commercial probiotic strains derived from fermented milk products and related sources currently marketed in European countries, to inhibit, compete and displace the adhesion of selected potential pathogens to immobilized human mucus. The adhesion was assessed by measuring the radioactivity of bacteria adhered to the human mucus. We tested 12 probiotic strains against eight selected pathogens. All strains tested were able to adhere to mucus. All probiotic strains tested were able to inhibit and displace (P<0.05) the adhesion of Bacteroides, Clostridium, Staphylococcus and Enterobacter. In addition, the abilities to inhibit and to displace adhered pathogens depended on both the probiotic and the pathogen strains tested suggesting that several complementary mechanisms are implied in the processes. Our results indicate the need for a case-by-case assessment in order to select strains with the ability to inhibit or displace a specific pathogen. Probiotics could be useful to correct deviations observed in intestinal microbiota associated with specific diseases and also, to prevent pathogen infections. The competitive exclusion properties of probiotics as well as their ability to displace and inhibit pathogens are the most importance for therapeutic manipulation of the enteric microbiota. The application of such strategies could contribute to expand the beneficial properties on human health against pathogen infection.

Multi-parameter fibre Bragg grating sensor-array for thermal vacuum cycling test

NASA Astrophysics Data System (ADS)

Cheng, L.; Ahlers, B.; Toet, P.; Casarosa, G.; Appolloni, M.

2017-11-01

Fibre Bragg Grating (FBG) sensor systems based on optical fibres are gaining interest in space applications. Studies on Structural Health Monitoring (SHM) of the reusable launchers using FBG sensors have been carried out in the Future European Space Transportation Investigations Programme (FESTIP). Increasing investment in the development on FBG sensor applications is foreseen for the Future Launchers Preparatory Programme (FLPP). TNO has performed different SHM measurements with FBGs including on the VEGA interstage [1, 2] in 2006. Within the current project, a multi-parameter FBG sensor array demonstrator system for temperature and strain measurements is designed, fabricated and tested under ambient as well as Thermal Vacuum (TV) conditions in a TV chamber of the European Space Agency (ESA), ESTEC site. The aim is the development of a multi-parameters measuring system based on FBG technology for space applications. During the TV tests of a Space Craft (S/C) or its subsystems, thermal measurements, as well as strain measurements are needed by the engineers in order to verify their prediction and to validate their models. Because of the dimensions of the test specimen and the accuracy requested to the measurement, a large number of observation/measuring points are needed. Conventional sensor systems require a complex routing of the cables connecting the sensors to their acquisition unit. This will add extra weight to the construction under test. FBG sensors are potentially light-weight and can easily be multiplexed in an array configuration. The different tasks comply of a demonstrator system design; its component selection, procurement, manufacturing and finally its assembly. The temperature FBG sensor is calibrated in a dedicated laboratory setup down to liquid nitrogen (LN2) temperature at TNO. A temperature-wavelength calibration curve is generated. After a test programme definition a setup in thermal vacuum is realised at ESA premises including a mechanical

Relationship of race-, sexual orientation-, and HIV-related discrimination with adherence to HIV treatment: a pilot study.

PubMed

Boarts, Jessica M; Bogart, Laura M; Tabak, Melanie A; Armelie, Aaron P; Delahanty, Douglas L

2008-10-01

Adherence to highly active antiretroviral therapy (HAART) must be close to perfect in order to maintain suppression of HIV viral load, and to prevent the development of drug resistant strains of HIV. People living with HIV (PLWH) often report low levels of adherence. One variable that has been linked to poor adherence is perceived discrimination; however, research has generally not considered the possible unique effects of different types of discrimination on adherence. The present pilot study aimed to examine the association of three types of discrimination (due to HIV+ status, race, or sexual orientation) with adherence among 57 PLWH. Logistic regression analyses were conducted to demonstrate the relationships between each type of discrimination and self-reported adherence. Racial discrimination significantly predicted lower adherence levels, whereas sexual orientation- and HIV-related discrimination did not. Results underscore the importance of addressing discrimination issues, specifically racial, when designing interventions to improve adherence to HAART.

Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

PubMed

Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

2014-11-04

Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

Detection of diarrheagenic Escherichia coli strains isolated from dogs and cats in Brazil.

PubMed

Puño-Sarmiento, Juan; Medeiros, Leonardo; Chiconi, Carolina; Martins, Fernando; Pelayo, Jacinta; Rocha, Sérgio; Blanco, Jorge; Blanco, Miguel; Zanutto, Marcelo; Kobayashi, Renata; Nakazato, Gerson

2013-10-25

Escherichia coli are gut microbiota bacteria that can cause disease in some humans and other animals, including dogs and cats that humans often keep as pets. Diarrheagenic E. coli (DEC) strains are classified into six categories: enteropathogenic (EPEC), enterotoxigenic (ETEC), Shiga toxin-producing (STEC), enteroinvasive (EIEC), enteroaggregative (EAEC), and diffuse-adhering E. coli (DAEC). In this study 144 and 163 E. coli colonies were isolated from the fecal samples of 50 dogs and 50 cats, respectively, with and without diarrhea from a Veterinary Hospital (clinical isolates). The virulence factors were determined using multiplex Polymerase Chain Reaction. Adherence assays, antibacterial susceptibility and serotyping (somatic or flagellar antigens) were performed on DEC isolates. We found 25 (17.4%) and 4 (2.5%) DEC strains isolated from dogs and cats, respectively. Only the EPEC and EAEC pathotypes were found in both animals. Meanwhile, genes from other pathotypes (STEC, EIEC, and ETEC) were not found in these clinical isolates. All of the DEC strains showed mannose-resistant adherence to HEp-2 and HeLa cells, and aggregative adherence was predominant in these isolates. Multiresistant strains to antimicrobials were found in most DEC strains including usual and unusual antimicrobials in veterinary practices. The serotypes of these DEC isolates were variable. The ONT serotype was predominant in these isolates. Some serotypes found in our study were described to human DEC. Here, we demonstrate that pets carry virulent DEC genes, which are mainly strains of EPECs and EAECs. The presence of these virulence factors in isolates from animals without diarrhea suggests that pets can act as a reservoir for human infection. Copyright © 2013 Elsevier B.V. All rights reserved.

[Spectral analysis of fiber bragg grating modulated by double long period grating and its application in smart structure monitoring].

PubMed

Lu, Ji-Yun; Liang, Da-Kai; Zhang, Xiao-Li; Zhu, Zhu

2009-12-01

Spectrum of fiber bragg grating (FBG) sensor modulated by double long period grating (LPFG) is proposed in the paper. Double LPFG consists of two LPFGS whose center wavelengths are the same and reflection spectrum of FBG sensor is located in linear range of double LPFG transmission spectrum. Based on spectral analysis of FBG and double LPFG, reflection spectrum of FBG modulated by double LPFG is obtained and studied by use of band-hider filter characteristics for double LPFG. An FBG sensor is attached on the surface of thin steel beam, which is strained by bending, and the center wavelength of FBG sensor will shift. The spectral peak of FBG sensor modulated by double LPFG is changed correspondingly, and the spectral change will lead to variation in exit light intensity from double LPFG. Experiment demonstrates that the relation of filtering light intensity from double LPFG monitored by optical power meter to center wavelength change of FBG sensor is linear and the minimum strain of material (steel beam) detected by the modulation and demodulation system is 1.05 microepsilon. This solution is used in impact monitoring of optical fibre smart structure, and FBG sensor is applied for impulse response signal monitoring induced by low-velocity impact, when impact pendulum is loaded to carbon fiber-reinforced plastics (CFP). The acquired impact response signal and fast Fourier transform of the signal detected by FBG sensor agree with the measurement results of eddy current displacement meter attached to the FBG sensor. From the results, the present method using FBG sensor is found to be effective for monitoring the impact. The research provides a practical reference in dynamic monitoring of optical fiber smart structure field.

Repeatability of strain magnitude and strain rate measurements in the periodontal ligament using fibre Bragg gratings: An ex vivo study in a swine model.

PubMed

Romanyk, Dan L; Guan, Raymond; Major, Paul W; Dennison, Christopher R

2017-03-21

Measurement of periodontal ligament (PDL) strain in an ex vivo or in vivo setting of a complete tooth-PDL-bone complex (TPBC) has yet to be achieved in the literature. The objective of this study was to investigate inter- and intra-TPBC PDL strain measurement using fibre Bragg grating (FBG) strain sensors. Second and third premolars from the left and the right side of four swine mandibles were removed to yield sixteen TPBC samples. Samples were secured in a miniature load-frame equipped with a digital actuator used to apply apical-directed displacement to the tooth. The same tooth on left and right sides of the mouth were exposed to the same loading condition over ten trials allowing for comparisons in a split-mouth study. Displacements of 0.2 and 0.3mm were considered along with displacement rates of 0.025, 0.05, and 0.1mm/s, yielding six loading combinations. Hypothesis testing between left and right teeth revealed FBGs did not always measure the same strain between left and right TPBCs. For all strain measures, the average coefficient of variation (CV) (all data collected) was 2.16 (range: 0.274-10.71). For repeated measures in single TPBCs, the minimum CV ranged from 0.037 to 0.449, and generally coincided with the time of maximum strain measured over the test duration. Based on the findings of this study, it is suggested that FBGs can provide repeatable ex vivo strain measures in the PDL of complete TPBCs. Copyright © 2017 Elsevier Ltd. All rights reserved.

On-line monitoring of multi-component strain development in a tufting needle using optical fibre Bragg grating sensors

NASA Astrophysics Data System (ADS)

Chehura, Edmon; Dell'Anno, Giuseppe; Huet, Tristan; Staines, Stephen; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

2014-07-01

Dynamic loadings induced on a tufting needle during the tufting of dry carbon fibre preform via a commercial robot-controlled tufting head were investigated in situ and in real-time using optical fibre Bragg grating (FBG) sensors bonded to the needle shaft. The sensors were configured such that the axial strain and bending moments experienced by the needle could be measured. A study of the influence of thread and thread type on the strain imparted to the needle revealed axial strain profiles which had equivalent trends but different magnitudes. The mean of the maximum axial compression strains measured during the tufting of a 4-ply quasi-isotropic carbon fibre dry preform were - 499 ± 79 μɛ, - 463 ± 51 μɛ and - 431 ± 59 μɛ for a needle without thread, with metal wire and with Kevlar® thread, respectively. The needle similarly exhibited bending moments of different magnitude when the different needle feeding configurations were used.

Natural Variant of Collagen-Like Protein A in Serotype M3 Group A Streptococcus Increases Adherence and Decreases Invasive Potential

PubMed Central

Jewell, Brittany E.; Versalovic, Erika M.; Olsen, Randall J.; Bachert, Beth A.; Lukomski, Slawomir; Musser, James M.

2015-01-01

Group A Streptococcus (GAS) predominantly exists as a colonizer of the human oropharynx that occasionally breaches epithelial barriers to cause invasive diseases. Despite the frequency of GAS carriage, few investigations into the contributory molecular mechanisms exist. To this end, we identified a naturally occurring polymorphism in the gene encoding the streptococcal collagen-like protein A (SclA) in GAS carrier strains. All previously sequenced invasive serotype M3 GAS possess a premature stop codon in the sclA gene truncating the protein. The carrier polymorphism is predicted to restore SclA function and was infrequently identified by targeted DNA sequencing in invasive strains of the same serotype. We demonstrate that a strain with the carrier sclA allele expressed a full-length SclA protein, while the strain with the invasive sclA allele expressed a truncated variant. An isoallelic mutant invasive strain with the carrier sclA allele exhibited decreased virulence in a mouse model of invasive disease and decreased multiplication in human blood. Further, the isoallelic invasive strain with the carrier sclA allele persisted in the mouse nasopharynx and had increased adherence to cultured epithelial cells. Repair of the premature stop codon in the invasive sclA allele restored the ability to bind the extracellular matrix proteins laminin and cellular fibronectin. These data demonstrate that a mutation in GAS carrier strains increases adherence and decreases virulence and suggest selection against increased adherence in GAS invasive isolates. PMID:25561712

FBG in PVC foils for monitoring the knee joint movement during the rehabilitation process.

PubMed

Rocha, R P; Silva, A F; Carmo, J P; Correia, J H

2011-01-01

This paper presents a sensing electronic-free wearable solution for monitoring the body kinematics. The measuring of the knee movements, flexion and extension, with the corresponding joint acting as the rotation axis is shown as working principle. The proposed sensing system is based on a single optical Fiber-Bragg Grating (FBG) with a resonance wavelength of 1547.76 nm. The optical fiber with the FBG is placed inside a new polymeric foil composed by three flexible layers which facilitates its placement in the anatomic parts under investigation while maintaining full sensing capabilities. The way the device is placed in the specific body part to be measured enables the clear detection of the movements in respect to the joint. The proposed solution was tested using a prototype that was built to evaluate the device under different condition tests and also to assess the system's consistency. The designed and fabricated system demonstrates clear advantages in medical fields like physical therapy applications as optical fiber is not affected by electromagnetic interference nor does the system needs complex and expensive electronic systems and mechanical parts. Another advantage is the possibility to measure, record and evaluate specific mechanical parameters of the limbs' motion. Patients with bone, muscular and joint related health conditions, as well as athletes, are within the most important end-user applications.

Reduced adherence of Candida to silane-treated silicone rubber.

PubMed

Price, C L; Williams, D W; Waters, M G J; Coulthwaite, L; Verran, J; Taylor, R L; Stickler, D; Lewis, M A O

2005-07-01

Silicone rubber is widely used in the construction of medical devices that can provide an essential role in the treatment of human illness. However, subsequent microbial colonization of silicone rubber can result in clinical infection or device failure. The objective of this study was to determine the effectiveness of a novel silane-treated silicone rubber in inhibiting microbial adherence and material penetration. Test material was prepared by a combination of argon plasma discharge treatment and fluorinated silane coupling. Chemicophysical changes were then confirmed by X-ray photoelectron spectroscopy, contact-angle measurement, and atomic force microscopy. Two separate adherence assays and a material penetration assay assessed the performance of the new material against four strains of Candida species. Results showed a significant reduction (p < 0.01) of Candida albicans GDH 2346 adherence to silane-treated silicone compared with untreated controls. This reduction was still evident after the incorporation of saliva into the assay. Adherence inhibition also occurred with Candida tropicalis MMU and Candida krusei NCYC, although this was assay dependent. Reduced penetration of silane-treated silicone by Candida was evident when compared to untreated controls, plaster-processed silicone, and acrylic-processed silicone. To summarize, a novel silicone rubber material is described that inhibits both candidal adherence and material penetration. The clinical benefit and performance of this material remains to be determined. Copyright 2005 Wiley Periodicals, Inc.

Eradication rate of Helicobacter Pylori infection is directly influenced by adherence to therapy in children.

PubMed

Kotilea, Kallirroi; Mekhael, Joyce; Salame, Assaad; Mahler, Tania; Miendje-Deyi, Veronique Yvette; Cadranel, Samy; Bontems, Patrick

2017-08-01

Current commonly accepted strategies to eradicate Helicobacter pylori in children are a 10-day sequential treatment or a triple therapy for 7-14 days. To avoid further expensive and possibly risky investigations as well as induction of secondary antimicrobial resistance, a success rate of elimination strategies over 90% in a per-protocol analysis is the target goal but rates observed in clinical trials are lower. Antimicrobial resistance is a well-recognized risk factor for treatment failure; therefore, only a treatment tailored to susceptibility testing should be recommended. Adherence to therapy is also a risk factor for treatment failure but that has been poorly studied. The purpose of this study was to evaluate the influence of adherence to therapy on the elimination rates obtained with different treatment regimens. Cohort study analysis of children, aged 2-17 years, treated for Helicobacter pylori infection between October 2011 and December 2013. As a routine clinical practice, children infected with a strain susceptible to clarithromycin and to metronidazole received either a sequential regimen or a 10-day triple therapy while children infected with a strain resistant to clarithromycin or metronidazole received a 10-day triple regimen tailored to antimicrobial susceptibility. The eradication rate was assessed by a negative 13 C-urea breath test performed at least 8 weeks after the end of the treatment and adherence evaluated using a diary. One hundred forty-five children (67 girls/78 boys, median age 9.7 years) fulfilled the inclusion criteria, 118 being infected with a strain susceptible to both clarithromycin and metronidazole, 10 with a clarithromycin resistant, and 17 with a metronidazole resistant strain. A sequential regimen was prescribed in 44, a triple therapy containing clarithromycin in 84 and containing metronidazole in 17. Follow-up data were available for 130/145 and clearance of the infection observed in 105 of them. A concordance of more than

Rethinking adherence.

PubMed

Steiner, John F

2012-10-16

In 2012, the Centers for Medicare & Medicaid Services (CMS) will introduce measures of adherence to oral hypoglycemic, antihypertensive, and cholesterol-lowering drugs into its Medicare Advantage quality program. To meet these quality goals, delivery systems will need to develop and disseminate strategies to improve adherence. The design of adherence interventions has too often been guided by the mistaken assumptions that adherence is a single behavior that can be predicted from readily available patient characteristics and that individual clinicians alone can improve adherence at the population level.Effective interventions require recognition that adherence is a set of interacting behaviors influenced by individual, social, and environmental forces; adherence interventions must be broadly based, rather than targeted to specific population subgroups; and counseling with a trusted clinician needs to be complemented by outreach interventions and removal of structural and organizational barriers. To achieve the adherence goals set by CMS, front-line clinicians, interdisciplinary teams, organizational leaders, and policymakers will need to coordinate efforts in ways that exemplify the underlying principles of health care reform.

Inhibition of adherence of C. albicans to dental implants and cover screws by Cymbopogon nardus essential oil and citronellal.

PubMed

Trindade, Leonardo Antunes; de Araújo Oliveira, Julyana; de Castro, Ricardo Dias; de Oliveira Lima, Edeltrudes

2015-12-01

This study investigated the biological activity of the essential oil from Cymbopogon nardus and of the phytoconstituent citronellal on Candida strains as to the inhibition of adherence to dental implants and cover screws. The essential oil was analyzed by gas chromatography coupled to mass spectrometry (GC-MS) and had its MIC and MFC determined against 12 strains of Candida. Then, tests of inhibition of adherence to the dental implants and cover screws were carried out using the MIC of the substances, followed by scanning electron microscopy analysis. Nystatin and chlorhexidine were used as positive controls, and experiments were performed in triplicate. The analysis by GC-MS of the essential oil identified citronellal as the major compound. The MICs of the essential oil, citronellal, chlorhexidine, and nystatin--able to inhibit 100 % of the strains--were found to be 64, 512, 64, and 32 μg/ml, respectively. The essential oil significantly inhibited the adherence of Candida albicans to the dental implants and cover screws (p < 0.001). Citronellal inhibited yeast adherence only to the dental implants (p < 0.001), and no significant results were found for the cover screws (p > 0.05) compared to the growth control. The essential oil and citronellal have proven antifungal activity and are able to inhibit the in vitro adherence of C. albicans. There has been a search for alternative natural product-containing formulations that should be effective in inhibiting adherence of yeasts to the surfaces of materials and also able to treat oral fungal infections. Further trials could make these products an alternative to chemical removal of peri-implant biofilm.

Composite material embedded fiber-optic Fabry-Perot strain rosette

NASA Astrophysics Data System (ADS)

Valis, Thomas; Hogg, Dayle; Measures, Raymond M.

1990-12-01

A fiber-optic strain rosette is embedded in Kevlar/epoxy. The individual arms of the rosette are fiber Fabry-Perot interferometers operated in reflection-mode with gauge (i.e., cavity) lengths of approximately 5 mm. Procedures for manufacturing the cavities, and bending the fibers, to form a strain rosette are described. Experimental results showing 2D interlaminar strain-tensor measurement are presented. The sensor is also tested as a surface adhered device.

High-sensitivity stress sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

NASA Astrophysics Data System (ADS)

Wang, Tongxin; Luo, Yanhua; Peng, Gang-Ding; Zhang, Qijin

2012-02-01

Bragg grating in a single-mode photosensitive polymer optical fiber (POF) with benzil dimethyl ketal (BDK)-doped in core has been inscribed through the Sagnac ring interference method. The Bragg wavelength of grating is about 1570nm. The stress and strain response of fiber Bragg grating (FBG) has been studied respectively. By fitting the experimental result, the strain sensitivity of FBG in POF has been found to be almost same to that of conventional silica fiber Bragg gratings. However, the stress sensitivity of FBG in POF is measured to be 421pm/MPa, which is 28 times higher than FBG in silica fiber. And such high stress sensitivity makes Bragg grating in a single-mode BDK-doped POF appear to be very attractive for constructing stress sensor with high resolution.

Nonlinear temperature dependence of glue-induced birefringence in polarization maintaining FBG sensors

NASA Astrophysics Data System (ADS)

Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

2016-05-01

Glue-induced stresses decrease the accuracy of surface-mounted fiber Bragg gratings (FBG). Significant temperature dependent glue-induced birefringence was verified when a thermally cured epoxy-based bonding technique had been used. Determining the peak separation of two azimuthally aligned FBGs in PM fibers combined with a polarization resolved measurement set-up in a temperature range between -30°C and 150°C revealed high glue-induced stresses at low temperatures. Peak separations of about 60 pm and a nonlinear temperature dependence of the glue-induced birefringence due to stress relaxation processes and a visco-elastic behavior of the used adhesive have been shown.

A retrospective discussion of the prognostic value of combining prothrombin time(PT) and fibrinogen(Fbg) in patients with Hepatocellular carcinoma.

PubMed

Wang, Xue-Ping; Mao, Min-Jie; He, Zhong-Lian; Zhang, Lin; Chi, Pei-Dong; Su, Jia-Rui; Dai, Shu-Qin; Liu, Wan-Li

2017-01-01

Aims: The levels of coagulation system tests have been studied in various cancers. In this study, our aim is to evaluate the prognostic value of pretreatment plasma coagulation tests in hepatocellular carcinoma (HCC) patients. Patient and methods: A retrospective study was performed in 539 patients with HCC, and follow-up period was at least 60 months until recurrence or death. The prognostic significance of coagulation system tests (prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen) were determined by univariate and multivariate Cox hazard models. Then, according to the results of the multivariate analyses, we proposed the coagulation-Based Stage, which combined the independent risk factors (prothrombin time and fibrinogen). Results: Coagulation system tests including prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (Fbg) were analyzed. Patients with prolonged PT (≥12.1 sec) levels had significantly poor overall survival (OS) and disease-free survival (DFS), not only in the entire cohort (HR: 1.661, 95%CI: 1.125-2.451, p= 0.011 vs. HR: 1.660, 95%CI: 1.125-2.451, p= 0.011), but also in the subgroups stratified by pathological stage (stage I-II and stage III-IV). Additionally, high Fbg (≥2.83 g/L) levels experienced significantly decreased OS and DFS (HR: 2.158, 95%CI: 1.427-3.263, p< 0.001 vs. HR: 2.161, 95%CI: 1.429-3.267, p< 0.001), not only in the entire cohort but also in the subgroups stratified by pathological stage (stage I-II and stage III-IV). All the patients were then stratified (based on combined PT and Fbg) into three groups, The OS for HCC patients were (41.37±17.76), (31.83±19.84) and (18.68±18.41) months, and the DFS for HCC patients were (41.15±17.88), (31.65±19.81) and (18.66±18.39) months. Conclusions: Our findings suggest that the combination of plasma PT and Fbg levels should be evaluated as the valuable predictor of survival in patients with HCC.

Adherence of Escherichia coli O157:H7 to epithelial cells in vitro and in pig gut loops is affected by bacterial culture conditions

PubMed Central

Yin, Xianhua; Feng, Yanni; Wheatcroft, Roger; Chambers, James; Gong, Joshua; Gyles, Carlton L.

2011-01-01

The objectives of this study were to determine the effect of bacterial culture conditions on adherence of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain 86-24 in vivo to pig enterocytes and to compare the results with adherence in vitro to cultured HEp-2 and IPEC-J2 cells. Growth of O157:H7 in MacConkey broth (MB) resulted in almost no adherence to both HEp-2 and IPEC-J2 cells; prior exposure of the bacteria to pH 2.5 reduced adherence. There was greater adherence by bacteria from static cultures than by those from shaken cultures and by bacteria cultured in brain–heart infusion (BHI) plus NaHCO3 (BHIN) than by bacteria cultured in BHI. In contrast, in pig ileal loops, bacteria cultured in MB adhered well to enterocytes, and prior exposure to pH 2.5 had no effect on adherence. Among several media tested for their effect on bacterial adherence in the pig intestine, MB and BHIN proved to be the best. Bacterial adherence was dose-dependent and was more extensive in the ileum than in the colon. This study demonstrated that there are remarkable differences between culture conditions that promote adherence of an EHEC O157:H7 strain in vitro and in vivo, that culture conditions profoundly affect adherence to epithelial cells in vitro and in vivo, and that pig ileal loops are better suited to adherence studies than are colon loops. PMID:21731177

Operation Manual for the Intensity Based Interrogation of Fibre Bragg Grating Arrays on Vibrating Structures

DTIC Science & Technology

2011-01-01

based demodulation approach for the measurement of strains, induced by structural vibrations, using Fiber Bragg Gratings ( FBG ). This companion...provide the Frequency Response Functions from a series of FBG arrays attached to a vibrating structure. RELEASE LIMITATION Approved for... FBG arrays attached to a vibrating structure. Both this technical note and its companion technical report are formal contributions to an

Investigation of flow behaviour of coal particles in a pilot-scale fluidized bed gasifier (FBG) using radiotracer technique.

PubMed

Pant, H J; Sharma, V K; Kamudu, M Vidya; Prakash, S G; Krishanamoorthy, S; Anandam, G; Rao, P Seshubabu; Ramani, N V S; Singh, Gursharan; Sonde, R R

2009-09-01

Knowledge of residence time distribution (RTD), mean residence time (MRT) and degree of axial mixing of solid phase is required for efficient operation of coal gasification process. Radiotracer technique was used to measure the RTD of coal particles in a pilot-scale fluidized bed gasifier (FBG). Two different radiotracers i.e. lanthanum-140 and gold-198 labeled coal particles (100 gm) were independently used as radiotracers. The radiotracer was instantaneously injected into the coal feed line and monitored at the ash extraction line at the bottom and gas outlet at the top of the gasifier using collimated scintillation detectors. The measured RTD data were treated and MRTs of coal/ash particles were determined. The treated data were simulated using tanks-in-series model. The simulation of RTD data indicated good degree of mixing with small fraction of the feed material bypassing/short-circuiting from the bottom of the gasifier. The results of the investigation were found useful for optimizing the design and operation of the FBG, and scale-up of the gasification process.

Bacterial adherence to periurethral epithelial cells in girls prone to urinary-tract infections.

PubMed

Källenius, G; Winberg, J

1978-09-09

Bacterial adherence to epithelial cells from the periurethral region of 48 healthy girls aged over 2 years and of 76 girls with repeated urinary-tract infections was investigated. The infection-prone girls had a significantly higher mean number of adhering bacteria than the healthy controls ( P less than 0.01). This difference was valid irrespective of whether or not the infection-prone girls had urinary-tract infections at the time of investigation. Furthermore, statistically significantly higher numbers of a pyelonephritic strain of Escherichia coli (075:H-:K-non-typable) were found to adhere to washed periurethral cells from infection-prone girls than to cells from healthy controls. These characteristics of the periurethral epithelial cells may facilitate the primary periurethral colonisation which precedes infection of the urinary tract.

Miniature FBG-based fluidic flowmeter to measure hot oil and water

NASA Astrophysics Data System (ADS)

Liu, Zhengyong; Htein, Lin; Cheng, Lun-Kai; Martina, Quincy; Jansen, Rob; Tam, Hwa-Yaw

2017-04-01

In this paper, we present a miniature fluidic flowmeter based on a packaged FBG and laser-heated fibers. The flow rates of water and hydraulic oil were measured by utilizing the proposed flowmeter. The measured results exhibited good sensitivity of 0.339 nm/(m/s) for water and 0.578 nm/(m/s) for oil flow. Experimental results showed that the sensitivity of the fluidic flow sensor is depending on the heat capacity of the fluids, where the fluid with higher heat capacity has higher sensitivity and lower detection limit at the same measurement condition. The real-time flow rates measured by the proposed sensor and a commercial flowmeter installed in the test rig were also compared, demonstrating good agreement with correlation coefficient of 0.9974.

Ultra-short FBG based distributed sensing using shifted optical Gaussian filters and microwave-network analysis.

PubMed

Cheng, Rui; Xia, Li; Sima, Chaotan; Ran, Yanli; Rohollahnejad, Jalal; Zhou, Jiaao; Wen, Yongqiang; Yu, Can

2016-02-08

Ultrashort fiber Bragg gratings (US-FBGs) have significant potential as weak grating sensors for distributed sensing, but the exploitation have been limited by their inherent broad spectra that are undesirable for most traditional wavelength measurements. To address this, we have recently introduced a new interrogation concept using shifted optical Gaussian filters (SOGF) which is well suitable for US-FBG measurements. Here, we apply it to demonstrate, for the first time, an US-FBG-based self-referencing distributed optical sensing technique, with the advantages of adjustable sensitivity and range, high-speed and wide-range (potentially >14000 με) intensity-based detection, and resistance to disturbance by nonuniform parameter distribution. The entire system is essentially based on a microwave network, which incorporates the SOGF with a fiber delay-line between the two arms. Differential detections of the cascaded US-FBGs are performed individually in the network time-domain response which can be obtained by analyzing its complex frequency response. Experimental results are presented and discussed using eight cascaded US-FBGs. A comprehensive numerical analysis is also conducted to assess the system performance, which shows that the use of US-FBGs instead of conventional weak FBGs could significantly improve the power budget and capacity of the distributed sensing system while maintaining the crosstalk level and intensity decay rate, providing a promising route for future sensing applications.

The effect of a probiotic strain (Lactobacillus acidophilus) on the plaque formation of oral Streptococci.

PubMed

Tahmourespour, Arezoo; Kermanshahi, Rooha Kasra

2011-02-01

The objective of this study was to investigate the ability of biofilm formation among mutans and non mutans oral streptococci and to determine the effect of Lactobacillus acidophilus DSM 20079 as a probiotic strain on the adhesion of selected streptococcal strains on the surfaces. The sample comprised 40 isolates of oral streptococci from dental plaque and caries of volunteer persons. Streptococcus mutans ATCC35668 (no24) was as an standard strain. The probiotic strain was Lactobacillus acidophilus DSM 20079. The ability of biofilm formation was investigated with colorimetric method and the strongest isolates were selected. Then the effect of probiotic strain on the adhesion of streptococci isolates was determined in polystyrene microtiter plate simultaneously and 30 minutes before streptococci entrance to the system. The results showed that 42% of mutans streptococci were strongly adherent (SA) and in non mutans streptococci, only 23.5% of isolates were found strongly adherent. The strong biofilm forming bacterium isolated was Streptococcus mutans strain22. In the next step, in the presence of probiotic strain the streptococcal adhesion were reduced, and this reduction was non significantly stronger if the probiotic strain was inoculated to the system before the oral bacteria. The Lactobacillus acidophilus had more effect on adherence of mutans streptococci than non mutans streptococci with significant difference (p < 0.05). Adhesion reduction is likely due to bacterial interactions and colonization of adhesion sites with probiotic strain before the presence of streptococci. Adhesion reduction can be an effective way on decreasing cariogenic potential of oral streptococci.

Smart sensing of aviation structures with fiber optic Bragg grating sensors

NASA Astrophysics Data System (ADS)

Trutzel, Michael N.; Wauer, Karsten; Betz, Daniel; Staudigel, Lothar; Krumpholz, Oskar; Muehlmann, Hans-Christian; Muellert, Thomas; Gleine, Wolfgang

2000-06-01

We developed a surface mounting technique where fiber-optic Bragg grating (FBG) sensors are glued to the surface of structures and tested the technique on the surface of a CFRP- wing at the DASA Airbus test center Hamburg for over one year. The FBG sensors were interrogated with a measurement system capable of determining the Bragg wavelength in a few seconds over a spectral range of 60 nm (around 1.53 μm) with an absolute accuracy better than 1 pm. A polarization scrambler was used to account for polarization effects. Excellent consistence between the values of electrical strain gauges and the FBG sensors were found during all measurements. However because this method shows drawbacks in a harsher environment such as a flight test, we are currently investigating the possibilities of integrating FBG sensors into the varnish of the structures. For reasons of their better mechanical performance we use FBG sensors produced on the fiber draw-tower with a special UV-curable coating. The sensors are integrated into an original Airbus varnish build- up. We observed linear strain sensitivities in a temperature range between -50 and +100 °C. Furthermore, at negative temperatures we found a vanish- induced polarization dependence which could be used to differentiate between strain and temperature effects.

Temperature-insensitive refractive index sensor based on tilted moiré FBG with high resolution.

PubMed

Wang, Tao; Liu, Kun; Jiang, Junfeng; Xue, Meng; Chang, Pengxiang; Liu, Tiegen

2017-06-26

We proposed and fabricated a tilted moiré FBG (TMFBG), whose grating section was made up of two consecutive scribed TFBGs. By adjusting the Bragg wavelengths and the tilt angles of the two TFBGs, the two cladding mode combs of the transmission spectrum are non-overlapped. When the TMFBG was used for refractive index detection, its resolution can reach 2 × 10 -7 RIU, which is an order of magnitude higher than that of a single TFBG. And this result also has a good performance of temperature-insensitivity.

Bioactivity characterization of Lactobacillus strains isolated from dairy products

PubMed Central

Haghshenas, Babak; Nami, Yousef; Haghshenas, Minoo; Abdullah, Norhafizah; Rosli, Rozita; Radiah, Dayang; Yari Khosroushahi, Ahmad

2015-01-01

This study aimed to find candidate strains of Lactobacillus isolated from sheep dairy products (yogurt and ewe colostrum) with probiotic and anticancer activity. A total of 100 samples were randomly collected from yogurt and colostrum and 125 lactic acid bacteria were isolated. Of these, 17 Lactobacillus strains belonging to five species (L. delbrueckii, L. plantarum, L. rhamnosus, L. paracasei, and L. casei) were identified. L. plantarum 17C and 13C, which isolated from colostrums, demonstrated remarkable results such as resistant to low pH and high concentrations of bile salts, susceptible to some antibiotics and good antimicrobial activity that candidate them as potential probiotics. Seven strains (1C, 5C, 12C, 13C, 17C, 7M, and 40M), the most resistant to simulated digestion, were further investigated to evaluate their capability to adhere to human intestinal Caco-2 cells. L. plantarum 17C was the most adherent strain. The bioactivity assessment of L. plantarum 17C showed anticancer effects via the induction of apoptosis on HT-29 human cancer cells and negligible side effects on one human epithelial normal cell line (FHs 74). The metabolites produced by this strain can be used as alternative pharmaceutical compounds with promising therapeutic indices because they are not cytotoxic to normal mammalian cells. PMID:26219634

Apa is a trimeric autotransporter adhesin of Actinobacillus pleuropneumoniae responsible for autoagglutination and host cell adherence.

PubMed

Xiao, Longwen; Zhou, Liang; Sun, Changjiang; Feng, Xin; Du, ChongTao; Gao, Yu; Ji, Qun; Yang, Shuxin; Wang, Yu; Han, Wenyu; Langford, P R; Lei, Liancheng

2012-10-01

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia, and adherence to host cells is a key step in the pathogenic process. Although trimeric autotransporter adhesins (TAAs) were identified in many pathogenic bacteria in recent years, none in A. pleuropneumoniae have been characterized. In this study, we identified a TAA from A. pleuropneumoniae, Apa, and characterized the contribution of its amino acid residues to the adhesion process. Sequence analysis of the C-terminal amino acid residues of Apa revealed the presence of a putative translocator domain and six conserved HsfBD1-like or HsfBD2-like binding domains. Western blot analysis revealed that the 126 C-terminal amino acids of Apa could form trimeric molecules. By confocal laser scanning microscopy, one of these six domains (ApaBD3) was determined to mediate adherence to epithelial cells. Adherence assays and adherence inhibition assays using a recombinant E. coli- ApaBD3 strain which expressed ApaBD3 on the surface of E. coli confirmed that this domain was responsible for the adhesion activity. Moreover, cellular enzyme-linked immunosorbent assays demonstrated that ApaBD3 mediated high-level adherence to epithelial cell lines. Intriguingly, autoagglutination was observed with the E. coli- ApaBD3 strain, and this phenomenon was dependent upon the association of the expressed ApaBD3 with the C-terminal translocator domain. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Initial Trial using Embedded Fibre Bragg Gratings for Distributed Strain Monitoring in a Shape Adaptive Composite Foil

DTIC Science & Technology

2012-02-01

available for interrogation. Although commercially available fibre Bragg grating ( FBG ) sensors have emerged in the marketplace over the past decade...the results from a preliminary trial investigating the feasibility of using embedded FBG arrays in a shape adaptive composite foil to characterise...The response from the FBG sensors was also monitored during fabrication of the foil during the resin infusion and curing stages of the process

Isolation of Adherent Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Bacteria Using PAH-Sorbing Carriers

PubMed Central

Bastiaens, Leen; Springael, Dirk; Wattiau, Pierre; Harms, Hauke; deWachter, Rupert; Verachtert, Hubert; Diels, Ludo

2000-01-01

Two different procedures were compared to isolate polycyclic aromatic hydrocarbon (PAH)-utilizing bacteria from PAH-contaminated soil and sludge samples, i.e., (i) shaken enrichment cultures in liquid mineral medium in which PAHs were supplied as crystals and (ii) a new method in which PAH degraders were enriched on and recovered from hydrophobic membranes containing sorbed PAHs. Both techniques were successful, but selected from the same source different bacterial strains able to grow on PAHs as the sole source of carbon and energy. The liquid enrichment mainly selected for Sphingomonas spp., whereas the membrane method exclusively led to the selection of Mycobacterium spp. Furthermore, in separate membrane enrichment set-ups with different membrane types, three repetitive extragenic palindromic PCR-related Mycobacterium strains were recovered. The new Mycobacterium isolates were strongly hydrophobic and displayed the capacity to adhere strongly to different surfaces. One strain, Mycobacterium sp. LB501T, displayed an unusual combination of high adhesion efficiency and an extremely high negative charge. This strain may represent a new bacterial species as suggested by 16S rRNA gene sequence analysis. These results indicate that the provision of hydrophobic sorbents containing sorbed PAHs in the enrichment procedure discriminated in favor of certain bacterial characteristics. The new isolation method is appropriate to select for adherent PAH-degrading bacteria, which might be useful to biodegrade sorbed PAHs in soils and sludge. PMID:10788347

Factors associated to acceptable treatment adherence among children with chronic kidney disease in Guatemala

PubMed Central

Cerón, Alejandro; Méndez-Alburez, Luis Pablo; Lou-Meda, Randall

2017-01-01

Pediatric patients with Chronic Kidney Disease face several barriers to medication adherence that, if addressed, may improve clinical care outcomes. A cross sectional questionnaire was administered in the Foundation for Children with Kidney Disease (FUNDANIER, Guatemala City) from September of 2015 to April of 2016 to identify the predisposing factors, enabling factors and need factors related to medication adherence. Sample size was calculated using simple random sampling with a confidence level of 95%, confidence interval of 0.05 and a proportion of 87%. A total of 103 participants responded to the questionnaire (calculated sample size was 96). Independent variables were defined and described, and the bivariate relationship to dependent variables was determined using Odds Ratio. Multivariate analysis was carried out using logistic regression. The mean adherence of study population was 78% (SD 0.08, max = 96%, min = 55%). The mean adherence in transplant patients was 82% (SD 7.8, max 96%, min 63%), and the mean adherence in dialysis patients was 76% (SD 7.8 max 90%, min 55%). Adherence was positively associated to the mother’s educational level and to higher monthly household income. Together predisposing, enabling and need factors illustrate the complexities surrounding adherence in this pediatric CKD population. Public policy strategies aimed at improving access to comprehensive treatment regimens may facilitate treatment access, alleviating economic strain on caregivers and may improve adherence outcomes. PMID:29036228

Factors associated to acceptable treatment adherence among children with chronic kidney disease in Guatemala.

PubMed

Ramay, Brooke M; Cerón, Alejandro; Méndez-Alburez, Luis Pablo; Lou-Meda, Randall

2017-01-01

Pediatric patients with Chronic Kidney Disease face several barriers to medication adherence that, if addressed, may improve clinical care outcomes. A cross sectional questionnaire was administered in the Foundation for Children with Kidney Disease (FUNDANIER, Guatemala City) from September of 2015 to April of 2016 to identify the predisposing factors, enabling factors and need factors related to medication adherence. Sample size was calculated using simple random sampling with a confidence level of 95%, confidence interval of 0.05 and a proportion of 87%. A total of 103 participants responded to the questionnaire (calculated sample size was 96). Independent variables were defined and described, and the bivariate relationship to dependent variables was determined using Odds Ratio. Multivariate analysis was carried out using logistic regression. The mean adherence of study population was 78% (SD 0.08, max = 96%, min = 55%). The mean adherence in transplant patients was 82% (SD 7.8, max 96%, min 63%), and the mean adherence in dialysis patients was 76% (SD 7.8 max 90%, min 55%). Adherence was positively associated to the mother's educational level and to higher monthly household income. Together predisposing, enabling and need factors illustrate the complexities surrounding adherence in this pediatric CKD population. Public policy strategies aimed at improving access to comprehensive treatment regimens may facilitate treatment access, alleviating economic strain on caregivers and may improve adherence outcomes.

Ultra-sensitive Chip-based Photonic Temperature Sensor Using Ring Resonator Structures

DTIC Science & Technology

2014-02-10

273.15 K to 373 K [15]. An optical analog of this, using infrared light to probe strain- free fiber Bragg gratings ( FBG ), exhibits temperature...sensors [9, 12, 13]. However, FBGs are susceptible to strain and are relatively large. Instead, we consider the use of ring resonators. In recent years...Traditionally, photonic thermometers such as those based on Fiber Bragg gratings ( FBG ) employ continuous wavelength scanning techniques to measure

Advances in Bio-Tactile Sensors for Minimally Invasive Surgery Using the Fibre Bragg Grating Force Sensor Technique:A Survey

PubMed Central

Abushagur, Abdulfatah A.G.; Arsad, Norhana; Ibne Reaz, Mamun; Ashrif, A.; Bakar, A.

2014-01-01

The large interest in utilising fibre Bragg grating (FBG) strain sensors for minimally invasive surgery (MIS) applications to replace conventional electrical tactile sensors has grown in the past few years. FBG strain sensors offer the advantages of optical fibre sensors, such as high sensitivity, immunity to electromagnetic noise, electrical passivity and chemical inertness, but are not limited by phase discontinuity or intensity fluctuations. FBG sensors feature a wavelength-encoding sensing signal that enables distributed sensing that utilises fewer connections. In addition, their flexibility and lightness allow easy insertion into needles and catheters, thus enabling localised measurements inside tissues and blood. Two types of FBG tactile sensors have been emphasised in the literature: single-point and array FBG tactile sensors. This paper describes the current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general. Providing MIS or microsurgery surgeons with accurate and precise measurements and control of the contact forces during tissues manipulation will benefit both surgeons and patients. PMID:24721774

Adherence-Specific Social Support Enhances Adherence to Calcium Supplementation Regimens among Pregnant Women.

PubMed

Martin, Stephanie L; Omotayo, Moshood O; Pelto, Gretel H; Chapleau, Gina M; Stoltzfus, Rebecca J; Dickin, Katherine L

2017-04-01

Background: WHO guidelines recommend integrating calcium supplementation into antenatal care (ANC) alongside iron and folic acid (IFA) to reduce maternal mortality. However, supplementation programs face multiple barriers, and strategies to improve adherence are needed. An adherence partner is someone whom pregnant women ask to support adherence at home. Objectives: This study 1 ) assessed adherence partner acceptability, feasibility, and associations with calcium and IFA supplement adherence and 2 ) examined relations between social support and adherence. Methods: This secondary analysis is from a trial integrating calcium supplementation into ANC in Kenya. ANC providers were trained on calcium and IFA supplementation and counseling, provided with behavior change materials, and given adequate supplement supplies. Pregnant women from 16 government health facilities were recruited ( n = 1036); sociodemographic and adherence data were collected at baseline and at 4- to 6-wk follow-up visits. Adherence was measured with pill counts and self-reports. Culturally adapted scales measured social support in general and specific to adherence. Mixed-effects regression analyses were used to examine factors associated with adherence partners, social support, and adherence. Results: Most participants received information about adherence partners (91%) and had a partner at follow-up (89%). Participants with adherence partners reported higher adherence support (OR: 2.10; 95% CI: 1.32, 3.34). Mean ± SD adherence was high for calcium (88.3% ± 20.7%) and IFA (86.1% ± 20.9%). Adherence support was positively associated with calcium adherence at follow-up by using pill counts (OR: 2.2; 95% CI: 1.1, 2.6) and self-report data (OR: 1.9; 95% CI: 1.2, 2.9), but there was not a direct relation between adherence partners and adherence. Conclusions: Adherence support enhanced adherence to calcium supplements. The adherence partner strategy was highly acceptable and feasible but warrants

Smart architecture for stable multipoint fiber Bragg grating sensor system

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Tsai, Ning; Zhuang, Yuan-Hong; Huang, Tzu-Jung; Chow, Chi-Wai; Chen, Jing-Heng; Liu, Wen-Fung

2017-12-01

In this work, we propose and investigate an intelligent fiber Bragg grating (FBG)-based sensor system in which the proposed stabilized and wavelength-tunable single-longitudinal-mode erbium-doped fiber laser can improve the sensing accuracy of wavelength-division-multiplexing multiple FBG sensors in a longer fiber transmission distance. Moreover, we also demonstrate the proposed sensor architecture to enhance the FBG capacity for sensing strain and temperature, simultaneously.

On-Orbit Assessment of Satellite Structural Properties via Robust Structural Health Monitoring

DTIC Science & Technology

2012-07-23

4-5] in aerospace applications. Compared to traditional SHM approaches using strain gages or Fiber Bragg Grating ( FBG ) sensors, the advantage of...decay model [20], principle stress directions for impact locations [21], use of Laser Doppler Vibrometer (LDV) [22] and FBG sensors [16, 23]. These...for Damage Localization in Flexural Structures Using Long-Gage FBG Sensors,” Structural Control Health Monitoring, Vol. 18, pp. 341-360, 2010. [24

Fixed combination of repaglinide and metformin in the management of type 2 diabetes.

PubMed

Moses, Robert

2009-06-24

Treatment to target fasting blood glucose (FBG), postprandial glucose (PPG) and HbA(1c) are essential in the management of type 2 diabetes to reduce the risk of vascular complications. Early combination therapy with oral agents is increasingly being seen as important to achieve this. Repaglinide, a rapid-acting insulin secretagogue, targets PPG, and metformin, an insulin sensitizer, targets FBG. Because of their complementary modes of action these therapies are frequently given as combination therapy in separate tablets. To overcome the issues with adherence to multiple tablets, repaglinide and metformin are now available in a fixed-dose combination (FDC). Repaglinide/metformin FDC is bioequivalent to each tablet given separately, suggesting that the efficacy and safety profile is similar. There is no effect of food on repaglinide when in the FDC. Repaglinide/metformin FDC is as effective in reducing HbA(1c) and FBG whether given twice or three times daily, with a similar safety profile. Repaglinide/metformin FDC twice daily is as effective in reducing HbA(1c) and FBG as rosiglitazone/metformin FDC with a similar safety profile, but unlike the rosiglitazone/metformin FDC, repaglinide/metformin FDC improves the lipid profile. Repaglinide/metformin FDC represents a new option in the pursuit of achieving glucose targets and reducing vascular risk in type 2 diabetes, with the advantage of improving adherence.

Fixed combination of repaglinide and metformin in the management of type 2 diabetes

PubMed Central

Moses, Robert

2009-01-01

Treatment to target fasting blood glucose (FBG), postprandial glucose (PPG) and HbA1c are essential in the management of type 2 diabetes to reduce the risk of vascular complications. Early combination therapy with oral agents is increasingly being seen as important to achieve this. Repaglinide, a rapid-acting insulin secretagogue, targets PPG, and metformin, an insulin sensitizer, targets FBG. Because of their complementary modes of action these therapies are frequently given as combination therapy in separate tablets. To overcome the issues with adherence to multiple tablets, repaglinide and metformin are now available in a fixed-dose combination (FDC). Repaglinide/metformin FDC is bioequivalent to each tablet given separately, suggesting that the efficacy and safety profile is similar. There is no effect of food on repaglinide when in the FDC. Repaglinide/metformin FDC is as effective in reducing HbA1c and FBG whether given twice or three times daily, with a similar safety profile. Repaglinide/metformin FDC twice daily is as effective in reducing HbA1c and FBG as rosiglitazone/metformin FDC with a similar safety profile, but unlike the rosiglitazone/metformin FDC, repaglinide/metformin FDC improves the lipid profile. Repaglinide/metformin FDC represents a new option in the pursuit of achieving glucose targets and reducing vascular risk in type 2 diabetes, with the advantage of improving adherence. PMID:21437123

Modeling FBG sensors sensitivity from cryogenic temperatures to room temperature as a function of metal coating thickness

NASA Astrophysics Data System (ADS)

Vendittozzi, Cristian; Felli, Ferdinando; Lupi, Carla

2018-05-01

Fiber optics with photo-imprinted Bragg grating have been studied in order to be used as temperature sensors in cryogenic applications. The main disadvantage presented by Fiber Bragg Grating (FBG) sensors is the significant drop in sensitivity as temperature decreases, mainly due to the critical lowering of the thermo-optic coefficient of the fiber and the very low thermal expansion coefficient (CTE) of fused silica at cryogenic temperatures. Thus, especially for the latter, it is important to enhance sensitivity to temperature by depositing a metal coating presenting higher CTE. In this work the thermal sensitivity of metal-coated FBG sensors has been evaluated by considering their elongation within temperature variations in the cryogenic range, as compared to bare fiber sensors. To this purpose, a theoretical model simulating elongation of metal-coated sensors has been developed. The model has been used to evaluate the behaviour of different metals which can be used as coating (Ni, Cu, Al, Zn, Pb and In). The optimal coating thickness has been calculated at different fixed temperature (from 5 K to 100 K) for each metal. It has been found that the metal coating effectiveness depends on thickness and operating temperature in accordance to our previous experimental work and theory suggest.

Development of a high resolution plantar pressure monitoring pad based on fiber Bragg grating (FBG) sensors.

PubMed

Suresh, R; Bhalla, S; Hao, J; Singh, C

2015-01-01

High importance is given to plantar pressure monitoring in the field of biomedical engineering for the diagnosis of posture related ailments associated with diseases such as diabetes and gonarthrosis. This paper presents the proof-of-concept development of a new high resolution plantar pressure monitoring pad based on fiber Bragg grating (FBG) sensors. In the proposed configuration, the FBG sensors are embedded within layers of carbon composite material (CCM) in turn conforming to an arc shape. A total of four such arc shaped sensors are instrumented in the pad at the locations of the forefoot and the hind foot. As a test of the pad, static plantar pressure is monitored on normal subjects under various posture conditions. The pad is evaluated both as a standalone platform as well as a pad inserted inside a standard shoe. An average pressure sensitivity of 1.2 pm/kPa and a resolution of approximately 0.8 kPa is obtained in this special configuration. The pad is found to be suitable in both configurations- stand-alone pad as well as an insert inside a standard shoe. The proposed set up offers a cost-effective high resolution and accurate plantar pressure measurement system suitable for clinical deployment. The novelty of the developed pressure pad lies in its ability to be used both as platform type as well as inserted in-sole type sensor system.

Damage Detection of CFRP Plates by Full-Spectral Analysis of a Fibre Bragg Grating Sensor Signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mizutani, Yoshihiro; Solid and Structures Engineering Laboratory, Department of Mechanical Sciences and Engineering, Tokyo Institute of Technology, Japan, 2-12-1-I1-70, Ookayama, Meguro-ku, Tokyo 152-8552; Groves, Roger M.

2010-05-28

This paper describes the measurement of average strain, strain distribution and vibration of cantilever beam made of Carbon Fiber Reinforced Plastics (CFRP), using a single Fibre Bragg Grating (FBG) sensor mounted on the beam surface. Average strain is determined from the displacement of the peak wavelength of reflected light from the FBG sensor. Unstrained reference FBG sensors were used to compensate for temperature drift and the photoelastic coefficient (P{sub e}), which was used to calculate the gauge factor. Measured strains agree with those measured by a resistance foil strain gauge attached to the sample. Stress distributions are measured by monitoringmore » the variation in the full width half maximum (FWHM) values of the reflected spectrum, using a proposed optical analytical model, described in the paper. FWHM values were measured for both the cantilever test beam and a for a reference beam, loaded using a four-point bending rig. The trend of the stress distribution for the test beam matches with our analytical model, however with a relatively large noise present in the experimentally determined data. The vibration of cantilever beam was measured by temporal analysis of the peak reflection wavelength. This technique is very stable as measurements are not affected by variations in the signal amplitude. Finally an application of FBG sensors for damage detection of CFRP plates is demonstrated, by measuring the average strain and natural frequency. With small defects of different sizes applied to the CFRP plate, average strains were seen to increase with damage size and the natural frequency decreased with damage size.« less

A Sensor-Type PC Strand with an Embedded FBG Sensor for Monitoring Prestress Forces

PubMed Central

Kim, Sung Tae; Park, YoungHwan; Park, Sung Yong; Cho, Keunhee; Cho, Jeong-Rae

2015-01-01

Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed. PMID:25580903

A sensor-type PC strand with an embedded FBG sensor for monitoring prestress forces.

PubMed

Kim, Sung Tae; Park, YoungHwan; Park, Sung Yong; Cho, Keunhee; Cho, Jeong-Rae

2015-01-08

Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed.

Microcantilever heater-thermometer with integrated temperature-compensated strain sensor

DOEpatents

King, William P [Champaign, IL; Lee, Jungchul [Champaign, IL; Goericke, Fabian T [Wolfsburg, DE

2011-04-19

The present invention provides microcantilever hotplate devices which incorporate temperature compensating strain sensors. The microcantilever hotplate devices of the present invention comprise microcantilevers having temperature compensating strain sensors and resistive heaters. The present invention also provides methods for using a microcantilever hotplate for temperature compensated surface stress measurements, chemical/biochemical sensing, measuring various properties of compounds adhered to the microcantilever hotplate surface, or for temperature compensated deflection measurements.

pH-responsive hydrogel coated fiber Bragg grating-based chemo mechanical sensor bioreactor applications

NASA Astrophysics Data System (ADS)

Kishore, P. V. N.; Sai Shankar, M.

2017-04-01

This paper describes a fiber optics based pH sensor by using wavelength modulated techniques. Fiber Bragg grating (FBG) is functionalized with a stimulus responsive hydrogel which induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of Poly (vinyl alcohol)/Poly (acrylic acid). The induced strain results in a shift of FBG reflected peak which is monitored by an interrogator. The sensor system shows a good linearity in acidic pH range of 3 to 7 with a sensitivity of 12.16pm/pH. Besides that it shows good repeatability which proves it to be fit for pH sensing applications.

Hydrogel-coated fiber Bragg grating sensor for pH monitoring

NASA Astrophysics Data System (ADS)

Pabbisetti, Vayu Nandana Kishore; Madhuvarasu, Sai Shankar

2016-06-01

We present a fiber-optic wavelength-modulated sensor for pH applications. Fiber Bragg grating (FBG) is functionalized with a stimulus-responsive hydrogel that induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of poly (vinyl alcohol)/poly (acrylic acid). The induced strain results in a shift of FBG reflected peak that is monitored by an interrogator. The sensor system shows good linearity in the acidic pH range of 3 to 7 with a sensitivity of 12.16 pm/pH. In addition, it shows good repeatability and oscillator behavior, which proves it to be fit for pH sensing applications.

Fiber Bragg Gratings for High-Temperature Thermal Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stinson-Bagby, Kelly L.; Fielder, Robert S.

2004-07-01

Fiber Bragg grating (FBG) sensors were used as a characterization tool to study the SAFE-100 thermal simulator at the Nasa Marshal Space Flight Center. The motivation for this work was to support Nasa space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. Distributed high temperature measurements, up to 1150 deg. C, were made with FBG temperature sensors. Additionally, FBG strain measurements were taken at elevated temperatures to provide a strain profile of the core during operation. This paper will discuss the contribution of these measurements to meet the goals of Nasa Marshallmore » Space Flight Center's Propulsion Research Center. (authors)« less

Determination of biofilm production by Candida tropicalis isolated from hospitalized patients and its relation to cellular surface hydrophobicity, plastic adherence and filamentation ability.

PubMed

Galán-Ladero, M A; Blanco-Blanco, M T; Hurtado, C; Pérez-Giraldo, C; Blanco, M T; Gómez-García, A C

2013-09-01

Candida tropicalis is an emerging virulent species. The aim of this study is to determine the biofilm-forming ability of 29 strains of C. tropicalis isolated from inpatients, and to examine its relation with other virulence factors such as cellular surface hydrophobicity (CSH), immediate (15 min, IA) and late (24 h, LA) plastic adherence and filamentation ability. The study was performed in parallel using two incubation temperatures - 37 and 22 °C - to determine the effect of growth temperature variations on these pathogenic attributes of C. tropicalis. Biofilm formation (BF) was measured by optical density (OD) and by XTT reduction (XTT); Slime index (SI), which includes growth as a correction factor in BF, was calculated in both methods. All strains were hydrophobic and adherent - at 15 min and 24 h - at both temperatures, with higher values for 22 °C; the adhered basal yeast layer appears to be necessary to achieve subsequent development of biofilm. Filamentation ability varied from 76.2% of strains at 37 °C to 26.6% at 22 °C. All C. tropicalis strains were biofilm producers, with similar results obtained using OD determination and XTT measurement to evaluation methods; SI is useful when good growth is not presented. BF at 37 °C was similar at 24 h and 96 h incubation; conversely, at 22 °C, the highest number of biofilm-producing strains was detected at 96 h. CSH is an important pathogenic factor which is involved in adherence, is influenced by the filamentation of yeast, and plays a critical role in BF. Copyright © 2013 John Wiley & Sons, Ltd.

Perspectives Regarding Adherence to Prescribed Treatment in Highly Adherent HIV-Infected Gay Men.

PubMed

Brion, John M; Menke, Edna M

2008-01-01

Focus group methodology was used to describe the medication adherence experience of 24 HIV-infected gay men who reported being adherent to their medication regimens. A conceptualization of medication adherence as an evolving process consisted of challenges to adherence (learning the diagnosis, starting the medications, struggling with the medications, dealing with side effects, coping with stigma) as well as those factors supportive of adherence (believing in medications, finding motivating factors, using reminders, depending on others, owning the disease). Themes associated with challenges to adherence focused on diagnosis and the physical and emotional adjustments individuals made to incorporate antiretroviral medications into their daily lives and move toward medication adherence. The factors supportive of adherence were related to the ongoing behaviors identified with establishing and maintaining adherence behaviors. What can be taken from the study is that adherence is a complex and dynamic process rather than a static behavior.

Temperature compensated liquid level sensor using FBGs and a Bourdon tube

NASA Astrophysics Data System (ADS)

Sengupta, D.; Shankar, M. Sai; Rao, P. Vengal; Reddy, P. Saidi; Sai Prasad, R. L. N.; Kishore, P.; Srimannarayana, K.

2011-12-01

A temperature compensated liquid level sensor using FBGs and a bourdon tube that works on hydrostatic pressure is presented. An FBG (FBG1) is fixed between free end and a fixed end of the bourdon tube. When hydrostatic pressure applied to the bourdon tube FBG1 experience an axial strain due to the movement of free end. Experimental result shows, a good linearity in shift in Bragg wavelength with the applied pressure. The performance of this arrangement is tested for 21metre water column pressure. Another FBG (FBG2) is included for temperature compensation. The design of the sensor head is simple and easy mountable external to any tank for liquid level measurements.

Virulence factors associated with cytotoxic necrotizing factor type two in bovine diarrheic and septicemic strains of Escherichia coli.

PubMed Central

Oswald, E; de Rycke, J; Lintermans, P; van Muylem, K; Mainil, J; Daube, G; Pohl, P

1991-01-01

Forty-three bovine isolates of Escherichia coli producing a second type of cytotoxic necrotizing factor (CNF2) and three K-12 strains carrying different Vir plasmids coding for CNF2 were tested for the presence of several virulence factors. Most of the strains were serum resistant (79%), produced an aerobactin (70%), and adhered to calf villi (53%); some of them produced a colicin (32%) and a hemolysin (9%). These strains were also tested by a colony hybridization assay with gene probes for six toxins (classical heat-stable [STaP and STb] and heat-labile [LT-I and LT-IIa] enterotoxins and Shiga-like toxins [SLT-I and SLT-II]) and five adhesion factors (K99, K88, 987P, F17, and F41). Only two gene probes, LT-IIa (9%) and F17A (53%), hybridized with the CNF2 strains. However, antibodies raised against F17 fimbriae did not agglutinate the strains hybridizing with the F17A probe. In contrast, all except one of these strains adhered to calf villi. Interestingly, these two properties, F17A positivity and adherence to calf villi, were the only ones expressed by the K-12 strains carrying different Vir plasmids. In conclusion, this study confirmed that CNF2-producing strains are unrelated to previously described toxigenic E. coli strains and also demonstrated that in half of the strains the production of CNF2 was associated with an adhesion factor genetically related to, but different from, F17, which is more than likely encoded by Vir plasmids. PMID:1774259

Study on the non-contact FBG vibration sensor and its application

NASA Astrophysics Data System (ADS)

Li, Tianliang; Tan, Yuegang; Zhou, Zude; Cai, Li; Liu, Sai; He, Zhongting; Zheng, Kai

2015-06-01

A non-contact vibration sensor based on the fiber Bragg grating (FBG) sensor has been presented, and it is used to monitor the vibration of rotating shaft. In the paper, we describe the principle of the sensor and make some experimental analyses. The analysis results show that the sensitivity and linearity of the sensor are -1.5 pm/μm and 4.11% within a measuring range of 2 mm-2.6 mm, respectively. When it is used to monitor the vibration of the rotating shaft, the analysis signals of vibration of the rotating shaft and the critical speed of rotation obtained are the same as that obtained from the eddy current sensor. It verifies that the sensor can be used for the non-contact measurement of vibration of the rotating shaft system and for fault monitoring and diagnosis of rotating machinery.

100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T

NASA Astrophysics Data System (ADS)

Ikeda, Akihiko; Nomura, Toshihiro; Matsuda, Yasuhiro H.; Tani, Shuntaro; Kobayashi, Yohei; Watanabe, Hiroshi; Sato, Keisuke

2018-05-01

High-speed 100 MHz strain monitor using fiber Bragg grating (FBG) and an optical filter has been devised for the magnetostriction measurements under ultrahigh magnetic fields. The longitudinal magnetostriction of LaCoO 3 has been measured at room temperature, 115, 7 and 4.2 K up to the maximum magnetic field of 150 T. The field-induced lattice elongations are observed, which are attributed to the spin-state crossover from the low-spin ground state to excited spin-states.

Isolation of adherent polycyclic aromatic hydrocarbon (PAH)-degrading bacteria using PAH-sorbing carriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bastiaens, L.; Springael, D.; Wattiau, P.

Two different procedures were compared to isolate polycyclic aromatic hydrocarbon (PAH)-utilizing bacteria from PAH-contaminated soil and sludge samples, i.e., (i) shaken enrichment cultures in liquid mineral medium in which PAHs were supplied as crystals and (ii) a new method in which PAH degraders were enriched on and recovered from hydrophobic membranes containing sorbed PAHs. Both techniques were successful, but selected from the same source different bacterial strains able to grow on PAHs as the sole source of carbon and energy. The liquid enrichment mainly selected for Sphingomonas spp., whereas the membrane method exclusively led to the selection of Mycobacterium spp.more » Furthermore, in separate membrane enrichment set-ups with different membrane types, three repetitive extragenic palindromic PCR-related Mycobacterium strains were recovered. The new Mycobactereium isolates were strongly hydrophobic and displayed the capacity to adhere strongly to different surfaces. One strain, Mycobacterium sp. LB501T, displayed an unusual combination of high adhesion efficiency and an extremely high negative charge. This strain may represent a new bacterial species as suggested by 16S rRNA gene sequence analysis. These results indicate that the provision of hydrophobic sorbents containing sorbed PAHs in the enrichment procedure discriminated in favor of certain bacterial characteristics. The new isolation method is appropriate to select for adherent PAH-degrading bacteria, which might be useful to biodegrade sorbed PAHs in soils and sludge.« less

Evaluation of the effects of sdiA, a luxR homologue, on adherence and motility of Escherichia coli O157 : H7.

PubMed

Sharma, Vijay K; Bearson, Shawn M D; Bearson, Bradley L

2010-05-01

Quorum-sensing (QS) signalling pathways are important regulatory networks for controlling the expression of genes promoting adherence of enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 to epithelial cells. A recent study has shown that EHEC O157 : H7 encodes a luxR homologue, called sdiA, which upon overexpression reduces the expression of genes encoding flagellar and locus of enterocyte effacement (LEE) proteins, thus negatively impacting on the motility and intimate adherence phenotypes, respectively. Here, we show that the deletion of sdiA from EHEC O157 : H7 strain 86-24, and from a hha (a negative regulator of ler) mutant of this strain, enhanced bacterial adherence to HEp-2 epithelial cells of the sdiA mutant strains relative to the strains containing a wild-type copy of sdiA. Quantitative reverse transcription PCR showed that the expression of LEE-encoded genes ler, espA and eae in strains with the sdiA deletions was not significantly different from that of the strains wild-type for sdiA. Similarly, no additional increases in the expression of LEE genes were observed in a sdiA hha double mutant strain relative to that observed in the hha deletion mutant. While the expression of fliC, which encodes flagellin, was enhanced in the sdiA mutant strain, the expression of fliC was reduced by several fold in the hha mutant strain, irrespective of the presence or absence of sdiA, indicating that the genes sdiA and hha exert opposing effects on the expression of fliC. The strains with deletions in sdiA or hha showed enhanced expression of csgA, encoding curlin of the curli fimbriae, with the expression of csgA highest in the sdiA hha double mutant, suggesting an additive effect of these two gene deletions on the expression of csgA. No significant differences were observed in the expression of the genes lpfA and fimA of the operons encoding long polar and type 1 fimbriae in the sdiA mutant strain. These data indicate that SdiA has no significant effect on the

Characterization of impact damage in woven fiber composites using fiber Bragg grating sensing and NDE

NASA Astrophysics Data System (ADS)

Hiche, Cristobal; Liu, Kuang C.; Seaver, Mark; Wei, Jun; Chattopadhyay, Aditi

2009-03-01

Woven fiber composites are currently being investigated due to their advantages over other materials, making them suitable for low weight, high stiffness, and high interlaminar fracture toughness applications such as missiles, body armor, satellites, and many other aerospace applications. Damage characterization of woven fabrics is a complex task due to their tendency to exhibit different failure modes based on the weave configuration, orientation, ply stacking and other variables. A multiscale model is necessary to accurately predict progressive damage. The present research is an experimental study on damage characterization of three different woven fiber laminates under low energy impact using Fiber Bragg Grating (FBG) sensors and flash thermography. A correlation between the measured strain from FBG sensors and the damaged area obtained from flash thermography imaging has been developed. It was observed that the peak strain in the fabrics were strongly dependent on the weave geometry and decreased at different rates as damage area increased due to dissimilar failure modes. Experimental observations were validated with the development of a multiscale model. A FBG sensor placement model was developed which showed that FBG sensor location and orientation plays a key role in the sensing capabilities of strain on the samples.

Application of fiber-Bragg-grating-based strain sensors for civil infrastructure health monitoring

NASA Astrophysics Data System (ADS)

Tjin, Swee C.; Rupali, S.; Moyo, Pilate; Brownjohn, James M. W.; Ngo, Nam Quoc

2003-10-01

Over past few years, the concept of structural health monitoring has been emerging as a new area of research. Fiber Bragg grating (FBG) based sensor offers a new sensing approach with a number of advantages over conventional sensors. This new sensing technology is suitable for the harsh environment of construction industry due to its robustness, ruggedness and ease of installation. Two unique advantages of FBG based sensors are immunity to electromagnetic interference and multiplexing capability. This paper reports some of the results of a multi-disciplinary program on the FBG based sensors involving the School of Electrical and Electronic Engineering and the School of Civil and Environment Engineering at Nanyang Technological University, Singapore.

Adherence of staphylococcus aureus to catheter tubing inhibition by quaternary ammonium compounds.

PubMed

Iyamba, Jean-Marie Liesse; Okombe, Daniel Tassa; Zakanda, Francis Nsimba; Malongo, Trésor Kimbeni; Unya, Joseph Welo; Lukukula, Cyprien Mbundu; Kikuni, Ntondo Za Balega Takaisi

2016-01-01

S. aureus is a Gram positive bacterium which is responsible for a wide range of infections. This pathogen has also the ability to adhere to biotic or abiotic surface such as central venous catheter (CVC) and to produce a biofilm. The aim of this study was to evaluate the effect of hexadecyltrimethyl ammonium bromide (HTAB) and Hexadecylbetainate chloride (HBC) on Staphylococcus aureus adherence to the catheter tubing and on bacteria growth. Broth microdilution method was used to determine the Minimal Inhibitory Concentration (MIC). The detection of slime production was done by Congo Red Agar method, and the adherence of bacteria to the catheter tubing was evaluated by the enumeration of bacteria on plate counts. The results of this study showed that the MICs of HTAB were ranged from 0.125 to 0.5 µg/mL, and those of HBC fluctuated between 2 to 8 µg/mL. HTAB and HBC inhibited bacteria adhesion on the surface of the catheter tubing. This study showed that HTAB and HBC can prevent the adherence of S. aureus strains to the surface of catheter tubing, suggesting that they could be used to prevent the risk of catheter related bloodstream infections.

Experimental technologies comparison for strain measurement of a composite main landing gear bay specimen

NASA Astrophysics Data System (ADS)

Viscardi, Massimo; Arena, Maurizio; Ciminello, Monica; Guida, Michele; Meola, Carosena; Cerreta, Pietro

2018-03-01

The development of advanced monitoring system for strain measurements on aeronautical components remain an important target both when related to the optimization of the lead-time and cost for part validation, allowing earlier entry into service, and when related to the implementation of advanced health monitoring systems dedicated to the in-service parameters verification and early stage detection of structural problems. The paper deals with the experimental testing of a composite samples set of the main landing gear bay for a CS-25 category aircraft, realized through an innovative design and production process. The test have represented a good opportunity for direct comparison of different strain measurement techniques: Strain Gauges (SG) and Fibers Bragg Grating (FBG) have been used as well as non-contact techniques, specifically the Digital Image Correlation (DIC) and Infrared (IR) thermography applied where possible in order to highlight possible hot-spot during the tests. The crucial points identification on the specimens has been supported by means of advanced finite element simulations, aimed to assessment of the structural strength and deformation as well as to ensure the best performance and the global safety of the whole experimental campaign.

A new deflection solution and application of a fiber Bragg grating-based inclinometer for monitoring internal displacements in slopes

NASA Astrophysics Data System (ADS)

Zheng, Yong; Huang, Da; Shi, Lin

2018-05-01

Landslide monitoring is critical for predicting the stability of slopes to ensure the safety of life and property. Considering the potential advantages of fiber Bragg gratings (FBGs), such as immunity to electromagnetic interference, resistance to hostile environments, light weight, and high measurement precision and real time response, a self-designed, FBG-based in situ inclinometer combining a traditional inclinometer and FBG technology was designed to monitor the inner deformation of a slope. In practical landslide monitoring, the inclinometer can be regarded as a cantilever beam with one end fixed. Based on the deflection curve equation of a normal beam and the composite Simpson integral equation, a theoretical deflection equation of the FBG-based inclinometer versus longitudinal strain was established. A FBG-based inclinometer was fabricated and calibrated in the laboratory and a calibration strain sensitivity coefficient was obtained. The results of calibration tests show that the displacements measured by dial indicators are in good agreement with the theoretical displacements calculated using the proposed equation. A series of FBG-based inclinometers were installed into three vertical boreholes located at different points on the profile of an actual reinforced slope. The in situ monitoring results show that the FBG-based inclinometer can effectively capture the real-time internal displacements and potential sliding surface of the slope, proving the validity of the proposed theoretical equation as well the reliability and practicality of the proposed FBG-based inclinometer in engineering applications.

Sialidases affect the host cell adherence and epsilon toxin-induced cytotoxicity of Clostridium perfringens type D strain CN3718.

PubMed

Li, Jihong; Sayeed, Sameera; Robertson, Susan; Chen, Jianming; McClane, Bruce A

2011-12-01

Clostridium perfringens type B or D isolates, which cause enterotoxemias or enteritis in livestock, produce epsilon toxin (ETX). ETX is exceptionally potent, earning it a listing as a CDC class B select toxin. Most C. perfringens strains also express up to three different sialidases, although the possible contributions of those enzymes to type B or D pathogenesis remain unclear. Type D isolate CN3718 was found to carry two genes (nanI and nanJ) encoding secreted sialidases and one gene (nanH) encoding a cytoplasmic sialidase. Construction in CN3718 of single nanI, nanJ and nanH null mutants, as well as a nanI/nanJ double null mutant and a triple sialidase null mutant, identified NanI as the major secreted sialidase of this strain. Pretreating MDCK cells with NanI sialidase, or with culture supernatants of BMC206 (an isogenic CN3718 etx null mutant that still produces sialidases) enhanced the subsequent binding and cytotoxic effects of purified ETX. Complementation of BMC207 (an etx/nanH/nanI/nanJ null mutant) showed this effect is mainly attributable to NanI production. Contact between BMC206 and certain mammalian cells (e.g., enterocyte-like Caco-2 cells) resulted in more rapid sialidase production and this effect involved increased transcription of BMC206 nanI gene. BMC206 was shown to adhere to some (e.g. Caco-2 cells), but not all mammalian cells, and this effect was dependent upon sialidase, particularly NanI, expression. Finally, the sialidase activity of NanI (but not NanJ or NanH) could be enhanced by trypsin. Collectively these in vitro findings suggest that, during type D disease originating in the intestines, trypsin may activate NanI, which (in turn) could contribute to intestinal colonization by C. perfringens type D isolates and also increase ETX action.

Microbial colonization of irradiated pathogenic yeast to catheter surfaces: Relationship between adherence, cell surface hydrophobicity, biofilm formation and antifungal susceptibility. A scanning electron microscope analysis.

PubMed

Farrag, Hala Abdallah; A-Karam El-Din, Alzahraa; Mohamed El-Sayed, Zeinab Galal; Abdel-Latifissa, Soheir; Kamal, Mona Mohamed

2015-06-01

Technological advances such as long-term indwelling catheters have created milieu in which infections are a major complication. Thus it is essential to be able to recognize, diagnose, and treat infections occurring in immunocompromised patients. Adherence assay and quantitation of biofilms was performed by a spectrophotometric method, hydrophobicity was evaluated by adhesion to p-xylene. The minimum inhibitory concentration (MIC) of Nystatin was carried out by a well dilution method. Out of 100 bladder cancer patients, 23 pathogenic yeast isolates were identified. The samples were taken from urinary catheters and urine collected from their attached drainage bags. Pathogenic yeast identified were species of Candida, Cryptococcus, Saccharomyces, Blastoschizomyces, Trichosporn, Hansenula, Prototheca and Rhodotorula. With the exception of Rhodotorula minuta, the yeast were sensitive to the antimycotic agent (Nystatin) used before and after in vitro gamma irradiation at 24.41 Gy as measured by a disc diffusion method. All tested yeast strains were slime producers and showed positive adherence reactions. There were considerable differences in adherence measurements after irradiation. An increase in adherence measurement values (using a spectrophotometric method) after irradiation were detected in four strains whereas eight other strains showed a reduction in their adherence reaction. The cell surface hydrophobicity (CSH) was evaluated by adhesion to p-xylene. Candida tropicalis showed a hydrophobic reaction with an increase in the cell surface hydrophobicity after irradiation. Scanning electron microscopy of irradiated C. tropicalis showed marked abnormalities in cell shape and size with significant reduction in adherence ability at the MIC level of Nystatin (4 μg/ml). More basic research at the level of pathogenesis and catheter substance is needed to design novel strategies to prevent fungal adherence and to inhibit biofilm formation.

High speed and high resolution interrogation of a fiber Bragg grating sensor based on microwave photonic filtering and chirped microwave pulse compression.

PubMed

Xu, Ou; Zhang, Jiejun; Yao, Jianping

2016-11-01

High speed and high resolution interrogation of a fiber Bragg grating (FBG) sensor based on microwave photonic filtering and chirped microwave pulse compression is proposed and experimentally demonstrated. In the proposed sensor, a broadband linearly chirped microwave waveform (LCMW) is applied to a single-passband microwave photonic filter (MPF) which is implemented based on phase modulation and phase modulation to intensity modulation conversion using a phase modulator (PM) and a phase-shifted FBG (PS-FBG). Since the center frequency of the MPF is a function of the central wavelength of the PS-FBG, when the PS-FBG experiences a strain or temperature change, the wavelength is shifted, which leads to the change in the center frequency of the MPF. At the output of the MPF, a filtered chirped waveform with the center frequency corresponding to the applied strain or temperature is obtained. By compressing the filtered LCMW in a digital signal processor, the resolution is improved. The proposed interrogation technique is experimentally demonstrated. The experimental results show that interrogation sensitivity and resolution as high as 1.25 ns/με and 0.8 με are achieved.

A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

PubMed Central

Lee, Hyung-Seok; Lee, Hwi Don; Kim, Hyo Jin; Cho, Jae Du; Jeong, Myung Yung; Kim, Chang-Seok

2014-01-01

A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system. PMID:25177803

Effect of Medicaid Policy Changes on Medication Adherence: Differences by Baseline Adherence.

PubMed

Amin, Krutika; Farley, Joel F; Maciejewski, Matthew L; Domino, Marisa E

2017-03-01

In 2001, the North Carolina (NC) Medicaid program reduced the number of days prescription supply that enrollees could fill from 100 days to 34 days and increased copayments for brand-name medications. Previous work has shown that a change in these policies led to a decrease in medication adherence from 2.9 to 8.0 percentage points in specific populations with chronic conditions. Studies have also shown that days supply limits and copayment increases have heterogeneous effects based on enrollees' baseline characteristics, including baseline adherence. However, this phenomenon has not been studied in the Medicaid population. We undertook this study to assess the heterogeneous effect of the NC Medicaid policy changes in groups with varying levels of baseline adherence. To examine whether restrictions on days supply had heterogeneous effects in subgroups defined by medication adherence before the policy changes. A partial difference-in-difference-in-differences model with fixed effects was used to compare medication adherence before and after the NC Medicaid policy changes among Medicaid enrollees subject to the policy changes because of their use of long prescriptions (> 40 days) as compared with (a) NC Medicaid enrollees using short prescriptions (< 40 days) before policy adoption, as well as (b) Medicaid enrollees in Georgia restricted to a 31 days supply through the study period. Medicaid enrollees were included if they filled a prescription for 1 of the following medication classes: antihypertensives, lipid-lowering drugs, or antipsychotics. The effect of the policy changes on medication adherence, calculated using the proportion of days covered (PDC) each quarter by baseline adherence level and clinical condition group, was studied. Average adherence levels over the 18-month prechange period were used to stratify individuals into 3 baseline adherence groups: fully adherent (PDC ≥ 80%), partially adherent (50%-79%), and nonadherent (PDC ≤ 50%). Enrollees fully

Compact and cost-effective multi-channel optical spectrometer for fine FBG sensing in IoT technology

NASA Astrophysics Data System (ADS)

Konishi, Tsuyoshi; Yamasaki, Yu

2018-02-01

Optical fiber sensor networks have attracted much attention in IoT technology and a fiber Bragg grating is one of key sensor devices there because of their advantages in a high affinity for optical fiber networks, compactness, immunity to electromagnetic interference and so on. Nevertheless, its sensitivity is not always satisfactory so as to be usable together with widespread cost-effective multi-channel spectrometers. In this paper, we introduce a new cost-effective approach for a portable multi-channel spectrometer with high spectral resolution and demonstrates some preliminary experimental results for fine FBG sensing.

Distinguishable circumferential inclined direction tilt sensor based on fiber Bragg grating with wide measuring range and high accuracy

NASA Astrophysics Data System (ADS)

Jiang, Shanchao; Wang, Jing; Sui, Qingmei

2015-11-01

One novel distinguishable circumferential inclined direction tilt sensor is demonstrated by incorporating two strain sensitivity fiber Bragg gratings (FBGs) with two orthogonal triangular cantilever beam and using one fiber Bragg grating (FBG) as temperature compensation element. According to spatial vector and space geometry, theory calculation model of the proposed FBG tilt sensor which can be used to obtain the azimuth and tile angle of the inclined direction is established. To obtain its measuring characteristics, calibration experiment on one prototype of the proposed FBG tilt sensor is carried out. After temperature sensitivity experiment data analysis, the proposed FBG tilt sensor exhibits excellent temperature compensation characteristics. In 2-D tilt angle experiment, tilt measurement sensitivities of these two strain sensitivity FBGs are 140.85°/nm and 101.01°/nm over a wide range of 60º. Further, azimuth and tile angle of the inclined direction can be obtained by the proposed FBG tilt sensor which is verified in circumferential angle experiment. Experiment data show that relative errors of azimuth are 0.55% (positive direction) and 1.14% (negative direction), respectively, and relative errors of tilt angle are all less than 3%. Experiment results confirm that the proposed distinguishable circumferential inclined direction tilt sensor based on FBG can achieve azimuth and tile angle measurement with wide measuring range and high accuracy.

Health monitoring for subway station structure by fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Zhou, Yao; Wang, Yuan-Feng; Han, Bing; Zhou, Zhi

2008-03-01

Fiber Bragg grating (FBG) sensors hold a great deal of potential for structural monitoring because of their high sensitivity and exceptional stability for long-term monitoring. FBG sensors have been applied to sense a number of physical measurands including strain, temperature, pressure etc. These applications are based on the same principle, i.e. the measurement of Bragg wavelength shift caused by the measurands. The characters and principle of FBG sensors have been introduced in detail. The relative experiment is done. The results show that FBG sensors have high sensitivity and long-term stability. It is feasible to use the sensors to the structural health monitoring (SHM). Cement hydration produces heat, which may provoke important temperature rises in massive structures. Such a high temperature may be a factor for cracking during the cooling phase. Thus, it is important to be able to calculate and control the heat to be produced by a given concrete at the mixture-proportioning stage. Theory of heat of hydration is also introduced in this paper. FBG sensors have been applied successfully in health monitoring for Guomao subway station structure. Compared with results measured by vibrating wire sensors and computed by finite element method, the monitoring results show temperature and strains can be accurately measured by FBG sensors. It is convenient to study on heat of hydration of massive concrete and guide structural design.

Monitoring of non-homogeneous strains in wood glued joints with embedded FBG optical sensors in mode I delamination tests

NASA Astrophysics Data System (ADS)

Maciel, R. S.; Frazão, O.; Morais, J. J. L.; Fernandes, J. R. A.

2013-11-01

In this work it is presented a study of the reflection spectra yielded by a Fiber Bragg Grating sensor embedded into an epoxy glue line between two wood arms, in a double cantilever beam (DCB) Mode I delamination test. The reflection spectra were obtained using a Spectral Analyzer Fibersensing Bragmeter FS2200SA in regular time intervals, as the stress applied to the laminates is continuously increased until fracture occurs. They initially show a typical Bragg grating reflection spectrum, which gradually changes into more complicated, multiple-peak spectra, resulting from a non-homogenous strain distribution along the board line. Based on these results, a model was derived for the variation of the grating effective index which fits the observed spectra when the irregular strain distribution is observed. This model consists of usual cosine description of Bragg grating effective index with linear phase variation, plus a logarithmic phase change along the fiber length, resulting in the increment of the grating wavelength with increasing distance from the load application point. Moreover, from this model the strain distribution along the grating is found, yielding the expected result.

Efficiency of a cleaning protocol for the removal of enterotoxigenic Staphylococcus aureus strains in dairy plants.

PubMed

Martin, José Guilherme Prado; de Oliveira E Silva, Gabriela; da Fonseca, Carolina Rodrigues; Morales, Caio Baptista; Souza Pamplona Silva, Caroline; Miquelluti, Daniel Lima; Porto, Ernani

2016-12-05

Staphylococci are considered a major concern in dairy plants mainly due to the intensive production flow, automation of processing plants and increased demand in the microbiological quality of dairy products. This study aimed to identify S. aureus strains isolated from three Brazilian dairy plants, evaluate the influence of time, temperature and contact surface on the bacterial adhesion process, as well as the efficiency of simulated hygiene and sanitation protocol in removing adhered cells. For genotypic analyses, the presence of icaA and icaD in strains was evaluated. Adherence assays were performed in biofilm reactor, comparing the influence of 2 temperatures (5°C and 35°C), 2 surfaces (stainless steel and polypropylene) and 4 contact times (3, 6, 12h and post-sanitization). To evaluate the process effectiveness in removing adhered cells, neutral detergent and sanitizing agent based on sodium hypochlorite were used in order to simulate the situation observed in one of the dairy plants analyzed. The presence of icaA and icaD genes was determined in 75.3% and 77.6% of strains, respectively; 70.6% of isolates showed both genes, whereas 17.6% showed no genes. Genes for enterotoxin production were found in all samples, relating to SEG and SEH toxins. The number of cells adhered on both surfaces was about 3 and 6 log 10 CFU/cm 2 at temperatures of 5°C and 35°C, respectively, for most situations evaluated, with significant increase over the evaluation period. In general, the temperature of 35°C favored greater adherence of S. aureus. At 5°C, there was a considerable number of adhered cells, but in populations significantly lower than those observed at 35°C. The cleaning and sanitizing protocol was ineffective in removing adhered cells; better performance of sodium hypochlorite was observed at 5°C, which should be related to lower adherence observed at this temperature. Thus, the process was not able to reduce the number of S. aureus bacteria adhered on both

Capsule impairs efficient adherence of Streptococcus agalactiae to intestinal epithelium in tilapias Oreochromis sp.

PubMed

Barato, P; Martins, E R; Vasquez, G M; Ramirez, M; Melo-Cristino, J; Martínez, N; Iregui, C

2016-11-01

Streptococcosis caused by Streptococcus agalactiae is one of the most important diseases in the tilapia aquaculture industry. The role of the capsule of Streptococcus agalactiae in adherence to fish surfaces has not been evaluated and the mechanism of capsular regulation during adhesion has not been described. The aim of this study was to evaluate the role of the capsule of S. agalactiae during adhesion to intestinal epithelium of tilapia (Oreochromis sp.) in an ex vivo infection model. We show that the capsule impairs the adhesion of bacteria to host intestinal epithelium. Wild type (WT) strain SaTiBe08-18 (S. agalactiae recovered from tilapia) had reduced adhesion (P < 0.0001) in comparison with its unencapsulated mutant of SaTiBe08-18 (Δcps). When WT was treated with sterile saline solution (pH 5) before infection of intestine explants, the adhesion was reached. The results suggest that the capsule impairs the adhesion of S. agalactiae to tilapia intestine and that the acidic milieu could regulate adherence of encapsulated strains. We found GlcNAc on the surface of adherent Δcps but not over the capsule in WT. This difference could be explained by the GlcNAc composition of Lancefield group B antigen and the peptidoglycan in GBS (Group B Streptococcus) and also may be related with better exposure of glycosylated adhesins in unencapsulated fish GBS. Understanding capsular regulation during adhesion of S. agalactiae may provide new leads to find a successful anti-adherence therapy to prevent streptococcosis in tilapia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flight demonstration of aircraft fuselage and bulkhead monitoring using optical fiber distributed sensing system

NASA Astrophysics Data System (ADS)

Wada, Daichi; Igawa, Hirotaka; Tamayama, Masato; Kasai, Tokio; Arizono, Hitoshi; Murayama, Hideaki; Shiotsubo, Katsuya

2018-02-01

We have developed an optical fiber distributed sensing system based on optical frequency domain reflectometry (OFDR) that uses long-length fiber Bragg gratings (FBGs). This technique obtains strain data not as a point data from an FBG but as a distributed profile within the FBG. This system can measure the strain distribution profile with an adjustable high spatial resolution of the mm or sub-mm order in real-time. In this study, we applied this OFDR-FBG technique to a flying test bed that is a mid-sized jet passenger aircraft. We conducted flight tests and monitored the structural responses of a fuselage stringer and the bulkhead of the flying test bed during flights. The strain distribution variations were successfully monitored for various events including taxiing, takeoff, landing and several other maneuvers. The monitoring was effective not only for measuring the strain amplitude applied to the individual structural parts but also for understanding the characteristics of the structural responses in accordance with the flight maneuvers. We studied the correlations between various maneuvers and strains to explore the relationship between the operation and condition of aircraft.

Patient adherence in COPD.

PubMed

Bourbeau, J; Bartlett, S J

2008-09-01

Patient adherence to treatment in chronic obstructive pulmonary disease (COPD) is essential to optimise disease management. As with other chronic diseases, poor adherence is common and results in increased rates of morbidity, healthcare expenditures, hospitalisations and possibly mortality, as well as unnecessary escalation of therapy and reduced quality of life. Examples include overuse, underuse, and alteration of schedule and doses of medication, continued smoking and lack of exercise. Adherence is affected by patients' perception of their disease, type of treatment or medication, the quality of patient provider communication and the social environment. Patients are more likely to adhere to treatment when they believe it will improve disease management or control, or anticipate serious consequences related to non-adherence. Providers play a critical role in helping patients understand the nature of the disease, potential benefits of treatment, addressing concerns regarding potential adverse effects and events, and encouraging patients to develop self-management skills. For clinicians, it is important to explore patients' beliefs and concerns about the safety and benefits of the treatment, as many patients harbour unspoken fears. Complex regimens and polytherapy also contribute to suboptimal adherence. This review addresses adherence related issues in COPD, assesses current efforts to improve adherence and highlights opportunities to improve adherence for both providers and patients.

Evaluation of adherence, hemagglutination, and presence of genes codifying for virulence factors of Acinetobacter baumannii causing urinary tract infection.

PubMed

Braun, Graziela; Vidotto, Marilda Carlos

2004-12-01

Acinetobacter baumannii is a strictly aerobic bacterium which causes severe infections, however its pathogenic characteristics are not well defined. Thirteen A. baumannii strains isolated from urine of hospitalized and nonhospitalized patients with different ages were investigated for the presence of virulence factors. The isolates belonged to biotypes 2, 6, and 9 and were sensitive to imipenem. The majority of them showed resistance to amikacin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, norfloxacin, and trimethoprim-sulfamethoxazole. None of A. baumannii strains presented genes codifying for 17 different virulence factors previously described in uropathogenic Escherichia coli, when tested by polymerase chain reaction (PCR). Nine isolates agglutinated human group AB erythrocytes, in presence of mannose, but none of them agglutinated group O erythrocytes. Adherence to polystyrene was observed in 7 isolates, and this result did not correlate with that obtained in hemagglutination assay. All the isolates were able to grow in iron-limiting conditions, showing that A. baumannii produces some type of siderophore. However, the genes iutA and fyuA, from iron uptake system of E. coli and Yersinia sp., respectively, were not present in the isolates, suggesting the presence of a different type of siderophore. The fimbriae of A. baumannii strains that mediates the adherence are possibly mannose-resistant, even though the mechanism of adherence to human epithelial cells still remains to be elucidated.

Thin film strain gage development program

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.

1983-01-01

Sputtered thin-film dynamic strain gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating strain-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire strain gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic strain measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.

Estimating respiratory rate from FBG optical sensors by using signal quality measurement.

PubMed

Yongwei Zhu; Maniyeri, Jayachandran; Fook, Victor Foo Siang; Haihong Zhang

2015-08-01

Non-intrusiveness is one of the advantages of in-bed optical sensor device for monitoring vital signs, including heart rate and respiratory rate. Estimating respiratory rate reliably using such sensors, however, is challenging, due to body movement, signal variation according to different subjects or body positions, etc. This paper presents a method for reliable respiratory rate estimation for FBG optical sensors by introducing signal quality estimation. The method estimates the quality of the signal waveform by detecting regularly repetitive patterns using proposed spectrum and cepstrum analysis. Multiple window sizes are used to cater for a wide range of target respiratory rates. Furthermore, the readings of multiple sensors are fused to derive a final respiratory rate. Experiments with 12 subjects and 2 body positions were conducted using polysomnography belt signal as groundtruth. The results demonstrated the effectiveness of the method.

Heart rate estimation from FBG sensors using cepstrum analysis and sensor fusion.

PubMed

Zhu, Yongwei; Fook, Victor Foo Siang; Jianzhong, Emily Hao; Maniyeri, Jayachandran; Guan, Cuntai; Zhang, Haihong; Jiliang, Eugene Phua; Biswas, Jit

2014-01-01

This paper presents a method of estimating heart rate from arrays of fiber Bragg grating (FBG) sensors embedded in a mat. A cepstral domain signal analysis technique is proposed to characterize Ballistocardiogram (BCG) signals. With this technique, the average heart beat intervals can be estimated by detecting the dominant peaks in the cepstrum, and the signals of multiple sensors can be fused together to obtain higher signal to noise ratio than each individual sensor. Experiments were conducted with 10 human subjects lying on 2 different postures on a bed. The estimated heart rate from BCG was compared with heart rate ground truth from ECG, and the mean error of estimation obtained is below 1 beat per minute (BPM). The results show that the proposed fusion method can achieve promising heart rate measurement accuracy and robustness against various sensor contact conditions.

Adherence of staphylococcus aureus to catheter tubing inhibition by quaternary ammonium compounds

PubMed Central

Iyamba, Jean-Marie Liesse; Okombe, Daniel Tassa; Zakanda, Francis Nsimba; Malongo, Trésor Kimbeni; Unya, Joseph Welo; Lukukula, Cyprien Mbundu; Kikuni, Ntondo za Balega Takaisi

2016-01-01

Introduction S. aureus is a Gram positive bacterium which is responsible for a wide range of infections. This pathogen has also the ability to adhere to biotic or abiotic surface such as central venous catheter (CVC) and to produce a biofilm. The aim of this study was to evaluate the effect of hexadecyltrimethyl ammonium bromide (HTAB) and Hexadecylbetainate chloride (HBC) on Staphylococcus aureus adherence to the catheter tubing and on bacteria growth. Methods Broth microdilution method was used to determine the Minimal Inhibitory Concentration (MIC). The detection of slime production was done by Congo Red Agar method, and the adherence of bacteria to the catheter tubing was evaluated by the enumeration of bacteria on plate counts. Results The results of this study showed that the MICs of HTAB were ranged from 0.125 to 0.5 µg/mL, and those of HBC fluctuated between 2 to 8 µg/mL. HTAB and HBC inhibited bacteria adhesion on the surface of the catheter tubing. Conclusion This study showed that HTAB and HBC can prevent the adherence of S. aureus strains to the surface of catheter tubing, suggesting that they could be used to prevent the risk of catheter related bloodstream infections. PMID:28250874

Impact of input FBG reflectivity and forward pump power on RIN transfer in ultralong Raman laser amplifiers.

PubMed

Rizzelli, Giuseppe; Iqbal, Md Asif; Gallazzi, Francesca; Rosa, Paweł; Tan, Mingming; Ania-Castañón, Juan Diego; Krzczanowicz, Lukasz; Corredera, Pedro; Phillips, Ian; Forysiak, Wladek; Harper, Paul

2016-12-12

Relative intensity noise transfer from the pump to the signal in 2nd-order ultra-long Raman laser amplifiers for telecommunications is characterized numerically and experimentally. Our results showcase the need for careful adjustment of the front FBG reflectivity and the relative contribution of forward pump power, and their impact on performance. Finally, our analysis is verified through a 10 × 30 GBaud DP-QPSK transmission experiment, showing a large Q factor penalty associated with the combination of high forward pumping and high reflectivities.

Perceived Impact of Motherhood on Adherence to Therapy in Mothers with Cystic Fibrosis.

PubMed

Ullrich, G; Bobis, I; Bewig, B

2015-11-01

To explore the stress related to motherhood and its perceived impact on adherence to therapy in women with cystic fibrosis (CF). Cross-sectional study with a purpose-designed questionnaire. 46/73 eligible women were enrolled and 38 returned the questionnaire. Mean age of mothers was 33.8 y  ± 7.1 y, mean age of firstborn child was 6.9 y  ± 5.7 y. Nine women had more than one biological child. 18 mothers (47%) were currently employed, 12 of whom worked 19 to 30 hours per week and none full-time. There were mothers who reported a detrimental effect on adherence (time constraints 38%; intentional nonadherence 42%), and mothers who reported that adherence had actually improved (29%). Both of these effects were related to daily CF therapy at home. By contrast, i. v. antibiotic therapy was less impaired by role strains, mainly due to home i. v. therapy being an alternative and/or due to intensive social support (husband, parents). Participants clearly addressed the importance of adherence and the need for adequate self-management in narrative comments. Motherhood may improve adherence to CF therapy as well as it may affect it negatively. Health caregivers are well-advised to address a possible detrimental effect, proactively. © Georg Thieme Verlag KG Stuttgart · New York.

Adherence to HAART therapy measured by electronic monitoring in newly diagnosed HIV patients in Botswana.

PubMed

Vriesendorp, Reinout; Cohen, Adam; Kristanto, Paulus; Vrijens, Bernard; Rakesh, Pande; Anand, Bene; Iwebor, Henry Uchechukwaka; Stiekema, Jacobus

2007-12-01

This pilot study was designed to evaluate the feasibility and benefits of electronic adherence monitoring of antiretroviral medications in HIV patients who recently started Highly Active Anti Retroviral Therapy (HAART) in Francistown, Botswana and to compare this with self-reporting. Dosing histories were compiled electronically using Micro Electro Mechanical Systems (MEMS) monitors to evaluate adherence to prescribed therapies. Thirty patients enrolled in the antiretroviral treatment program were monitored over 6 weeks. These patients were all antiretroviral (ARV) naïve. After each visit (mean three times) to the pharmacy, the data compiled by the monitors were downloaded. Electronic monitoring of adherence was compared to patient self-reports of adherence. The mean individual medication adherence level measured with the electronic device was 85% (range 21-100%). The mean adherence level measured by means of self-reporting was 98% (range 70-100%). Medication prescribed on a once-a-day dose base was associated with a higher adherence level (97.9% for efavirenz) compared with a twice-a-day regimen (88.4% for Lamivudine/Zidovudine). It is feasible to assess treatment adherence of patients living in a low resource setting on HAART by using electronic monitors. Adherence, even in the early stages of treatment, appears to be insufficient in some patients and may be below the level required for continuous inhibition of viral replication. This approach may lead to improved targeting of counselling about their medication intake of such patients in order to prevent occurrence of resistant viral strains due to inadequate inhibition of viral replication. In this pilot study a significant difference between the data recorded through the electronic monitors and those provided by self-reporting was observed.

Simultaneous measurement of the viability, aggregation, and live and dead adherence of Streptococcus crista, Streptococcus mutans and Actinobacillus actinomycetemcomitans in human saliva in relation to indices of caries, dental plaque and periodontal disease.

PubMed

Rudney, J D; Staikov, R K

2002-05-01

Salivary proteins have multiple functions and many share similar functions, which may be why it has been difficult to relate variations in their concentrations to oral health and ecology. An alternative is to focus on variations in the major functions of saliva. An hydroxyapatite-coated microplate model has been developed that simultaneously measures saliva-promoted bacterial viability, bacterial aggregation, and live and dead bacterial adherence, while simulating oral temperature and shearing forces from swallowing. That model was applied to resting whole and stimulated parotid saliva from 149 individuals, using representative strains of Streptococcus crista, S. mutans, and Actinobacillus actinomycetemcomitans. Two major factors were defined by multivariate analysis (this was successful only for whole-saliva). One factor was correlated with aggregation, live adherence and dead adherence for all three strains; the other was correlated with total viability of all three strains. Participants were grouped <25th percentile and >75th percentile for each factor. Those groups were compared for clinical indices of oral health. Caries scores were significantly lower in those with high scores for aggregation-adherence, regardless of whether total viability scores were low or high. Live bacteria always predominated on surfaces when live and dead adherence scores were expressed as ratios. However, participants with high scores for aggregation-adherence showed significantly more dead adherent bacteria than those with low scores (these ratios were uncorrelated with total viability). This finding may indicate that extreme differences in the ability to kill bacteria on surfaces can influence caries risk.

Ethical considerations in adherence research.

PubMed

Patel, Nupur U; Moore, Blake A; Craver, Rebekah F; Feldman, Steven R

2016-01-01

Poor adherence to treatment is a common cause of medical treatment failure. Studying adherence is complicated by the potential for the study environment to impact adherence behavior. Studies performed without informing patients about adherence monitoring must balance the risks of deception against the potential benefits of the knowledge to be gained. Ethically monitoring a patient's adherence to a treatment plan without full disclosure of the monitoring plan requires protecting the patient's rights and upholding the fiduciary obligations of the investigator. Adherence monitoring can utilize different levels of deception varying from stealth monitoring, debriefing after the study while informing the subject that some information had been withheld in regard to the use of adherence monitoring (withholding), informed consent that discloses some form of adherence monitoring is being used and will be disclosed at the end of the study (authorized deception), and full disclosure. Different approaches offer different benefits and potential pitfalls. The approach used must balance the risk of nondisclosure against the potential for confounding the adherence monitoring data and the potential benefits that adherence monitoring data will have for the research subjects and/or other populations. This commentary aims to define various methods of adherence monitoring and to provide a discussion of the ethical considerations that accompany the use of each method and adherence monitoring in general as it is used in clinical research.

Correlates of Pediatric CPAP Adherence.

PubMed

Hawkins, Stephen M M; Jensen, Emily L; Simon, Stacey L; Friedman, Norman R

2016-06-15

Obstructive sleep apnea (OSA) is a common pediatric condition characterized by recurrent partial or complete cessation of airflow during sleep, typically due to inadequate upper airway patency. Continuous positive airway pressure (CPAP) is a therapeutic option that reduces morbidity. Despite efforts to promote use, CPAP adherence is poor in both pediatric and adult populations. We sought to determine whether demographics, insurance status, OSA severity, therapeutic pressure, or comorbid conditions were associated with pediatric CPAP adherence. A retrospective review of adherence download data was performed on all pediatric patients with initiation or adjustment of CPAP treatment over a one-year period with documented in-laboratory CPAP titration. Patients were grouped as CPAP adherent or non-adherent, where adherence was defined as > 70% nightly use and average usage ≥ 4 hours per night. Differences between the groups were analyzed by χ(2) test. Overall, nearly half of participants were CPAP adherent (49%, 69/140). Of the demographic data collected (age, ethnicity, sex, insurance status), only female sex was associated with better adherence (60.9% vs 39.5% of males adherent; odds ratio [OR] = 2.41, 95%CI = 1.20-4.85; p = 0.01). Severity of OSA (diagnostic apnea-hypopnea index [AHI] and degree of hypoxemia), therapeutic pressure, and residual AHI did not impact CPAP adherence (p > 0.05). Patients with developmental delay (DD) were more likely to be adherent with CPAP than those without a DD diagnosis (OR = 2.55, 95%CI = 1.27-5.13; p = 0.007). Female patients with trisomy 21 tended to be more adherent, but this did not reach significance or account for the overall increased adherence associated with female sex. Our study demonstrates that adherence to CPAP therapy is poor but suggests that female sex and developmental delay are associated with better adherence. These findings support efforts to understand the pathophysiology of and to develop adherence

High carriage of adherent invasive E. coli in wildlife and healthy individuals.

PubMed

Rahmouni, Oumaïra; Vignal, Cécile; Titécat, Marie; Foligné, Benoît; Pariente, Benjamin; Dubuquoy, Laurent; Desreumaux, Pierre; Neut, Christel

2018-01-01

Adherent invasive Escherichia coli (AIEC) are suspected to be involved in the pathogenesis of inflammatory bowel diseases. Since AIEC was first described in 1999, despite important progress on its genomic and immune characterizations, some crucial questions remain unanswered, such as whether there exists a natural reservoir, or whether there is asymptomatic carriage. The ECOR collection, including E. coli strains isolated mainly from the gut of healthy humans and animals, constitutes an ideal tool to investigate AIEC prevalence in healthy condition. A total of 61 E. coli strains were examined for characteristics of AIEC. The adhesion, invasion and intramacrophage replication capabilities (AIEC phenotype) of 61 intestinal E. coli strains were determined. The absence of virulence-associated diarrheagenic E. coli pathotypes (EPEC, ETEC, EIEC, EHEC, DAEC, EAEC), and uropathogenic E. coli was checked. Out of 61 intestinal strains, 13 (21%) exhibit the AIEC phenotype, 7 are from human origin and 6 are from animal origin. Prevalence of AIEC strains is about 24 and 19% in healthy humans and animals respectively. These strains are highly genetically diverse as they are distributed among the main described phylogroups. Among E. coli strains from the ECOR collection, we also detected strains able to detach I-407 cells. Our study described for the first time AIEC strains isolated from the feces of healthy humans and animals.

Correlates of Pediatric CPAP Adherence

PubMed Central

Hawkins, Stephen M.M.; Jensen, Emily L.; Simon, Stacey L.; Friedman, Norman R.

2016-01-01

Study Objectives: Obstructive sleep apnea (OSA) is a common pediatric condition characterized by recurrent partial or complete cessation of airflow during sleep, typically due to inadequate upper airway patency. Continuous positive airway pressure (CPAP) is a therapeutic option that reduces morbidity. Despite efforts to promote use, CPAP adherence is poor in both pediatric and adult populations. We sought to determine whether demographics, insurance status, OSA severity, therapeutic pressure, or comorbid conditions were associated with pediatric CPAP adherence. Methods: A retrospective review of adherence download data was performed on all pediatric patients with initiation or adjustment of CPAP treatment over a one-year period with documented in-laboratory CPAP titration. Patients were grouped as CPAP adherent or non-adherent, where adherence was defined as > 70% nightly use and average usage ≥ 4 hours per night. Differences between the groups were analyzed by χ2 test. Results: Overall, nearly half of participants were CPAP adherent (49%, 69/140). Of the demographic data collected (age, ethnicity, sex, insurance status), only female sex was associated with better adherence (60.9% vs 39.5% of males adherent; odds ratio [OR] = 2.41, 95%CI = 1.20–4.85; p = 0.01). Severity of OSA (diagnostic apnea-hypopnea index [AHI] and degree of hypoxemia), therapeutic pressure, and residual AHI did not impact CPAP adherence (p > 0.05). Patients with developmental delay (DD) were more likely to be adherent with CPAP than those without a DD diagnosis (OR = 2.55, 95%CI = 1.27–5.13; p = 0.007). Female patients with trisomy 21 tended to be more adherent, but this did not reach significance or account for the overall increased adherence associated with female sex. Conclusions: Our study demonstrates that adherence to CPAP therapy is poor but suggests that female sex and developmental delay are associated with better adherence. These findings support efforts to understand the

Potentially probiotic Lactobacillus strains from traditional Kurdish cheese.

PubMed

Hashemi, Seyed Mohammad Bagher; Shahidi, Fakhri; Mortazavi, Seyed Ali; Milani, Elnaz; Eshaghi, Zarrin

2014-03-01

In this study, the probiotic potential of Lactobacillus strains isolated from traditional Kurdish cheese was investigated. The Lactobacillus strains were examined for resistance to gastric acidity and bile toxicity, antimicrobial activities, autoaggregation, coaggregation, hydrophobicity, adhesion to Caco-2 cells, and antibiotic susceptibility. The results showed that all strains tested tolerate acid gastric conditions (pH 2.0 and 3.0), and all of them were bile resistant (at 0.3 and 1% concentration). Although no antibacterial activity was detected in vitro assay for the treated (neutralized to pH 6.5 and treated with catalase) cell-free culture supernatant (CFCS) of strains, untreated CFCS showed strong antagonistic activity against two known pathogens bacteria. All strains exhibited a strong autoaggregating phenotype and manifested a high degree of coaggregation with pathogens. On the other hand, majority of studied strains were found sensitive to different antibiotics, such as ampicillin, penicillin, ciprofloxacin, chloramphenicol, erythromycin, rifampicin, and tetracycline, and were resistant to vancomycin and streptomycin. Finally, isolated strains showed good hydrophobicity and adherence to Caco-2 cell line, so they could be exploited for food manufacture.

Interferometric interrogation of π-phase shifted fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Srivastava, Deepa; Tiwari, Umesh; Das, Bhargab

2018-03-01

Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrates that high resolution weak dynamic strain measurement down to 4 pε /√{ Hz } is easily achievable. Preliminary experimental results are also presented as proof-of-concept of the proposed interrogation principle.

A fiber Bragg grating sensor system for estimating the large deflection of a lightweight flexible beam

NASA Astrophysics Data System (ADS)

Peng, Te; Yang, Yangyang; Ma, Lina; Yang, Huayong

2016-10-01

A sensor system based on fiber Bragg grating (FBG) is presented which is to estimate the deflection of a lightweight flexible beam, including the tip position and the tip rotation angle. In this paper, the classical problem of the deflection of a lightweight flexible beam of linear elastic material is analysed. We present the differential equation governing the behavior of a physical system and show that this equation although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. We used epoxy glue to attach the FBG sensors to specific locations upper and lower surface of the beam in order to measure local strain measurements. A quasi-distributed FBG static strain sensor network is designed and established. The estimation results from FBG sensors are also compared to reference displacements from the ANSYS simulation results and the experimental results obtained in the laboratory in the static case. The errors of the estimation by FBG sensors are analysed for further error-correction and option-design. When the load weight is 20g, the precision is the highest, the position errors ex and ex are 0.19%, 0.14% respectively, the rotation error eθ, is 1.23%.

In vitro adherence of Lactobacillus strains isolated from the vaginas of healthy Iranian women.

PubMed

Mousavi, Elham; Makvandi, Manoochehr; Teimoori, Ali; Ataei, Angila; Ghafari, Shokouh; Najafian, Mahin; Ourang, Ziba; Samarbaf-Zadeh, Alireza

2016-12-01

The lactobacilli are a part of the bacterial flora of the human vagina. Detection of normal Lactobacillus species in the vaginas of healthy women in different geographical locations, and evaluation of their specific properties, can aid in the selection of the best species for preventing sexually transmitted diseases in the future. This study was performed to isolate and identify the Lactobacillus species in the vaginas of healthy women and to evaluate the adherence of these lactobacilli to Vero and HeLa cell lines. The study included 100 women. Bacteria were isolated from healthy women and purified. Phenotypic and biochemical tests were performed to identify the lactobacilli. The Lactobacillus species were detected by molecular methods using polymerase chain reaction amplification of the full length of the 16S rDNA of the isolated bacteria. Several isolates of each species were then selected to study their adherence to Vero and HeLa cell lines. Among the 50 samples taken from healthy women meeting the inclusion criteria, Lactobacillus species were identified in 33 (66%) samples. Of these lactobacilli, 14 isolates were Lactobacillus crispatus, six (18.2%) were Lactobacillus gasseri, nine (27%) were Lactobacillus rhamnosus, and the rest were either Lactobacillus salivarius (6%) or Lactobacillus plantarum (6%). L. rhamnosus showed the greatest adhesion to the cells when compared to the other tested species. All the lactobacilli isolated in this study showed a smaller capacity for cell adherence when compared with control species. L. crispatus, L. rhamnosus, and L. gasseri were the dominant Lactobacillus species in the vaginas of healthy women in Iran. L. rhamnosus attached more readily to the cells than did the other species; therefore, this isolate is a good candidate for further studies on the potential health benefits and application of lactobacilli as probiotics. Copyright © 2016. Published by Elsevier Taiwan LLC.

Stability test of the silicon Fiber Bragg Grating embroidered on textile for joint angle measurement

NASA Astrophysics Data System (ADS)

Apiwattanadej, Thanit; Chun, Byung Jae; Lee, Hyub; Li, King Ho Holden; Kim, Young-Jin

2017-06-01

Recently, Fiber Bragg Grating (FBG) sensors are being used for motion tracking applications. However, the sensitivity, linearity and stability of the systems have not been fully studied. Herein, an embroidered optical Fiber Bragg Grating (FBG) on a stretchable supportive textile for elbow movement measurement was developed. The sensing principle of this system is based on the alteration of Bragg wavelength due to strain from the elbow movements. The relationship between elbow movements and reflected Bragg wavelength was found to be linear. The dynamic range of FBG sensor on elbow support is between 0 and 120 degree. Finally, the stability of the FBG sensor on the supportive textile was tested during the exercise and the cleaning process with water. The sensitivity of FBG sensors for joint angle measurement and the effect of the movement and cleaning process to signals from FBG sensors after using in the real activity will be the basis knowledge for design and actual implementation of future optical fiber based wearable devices.

An FBG acoustic emission source locating system based on PHAT and GA

NASA Astrophysics Data System (ADS)

Shen, Jing-shi; Zeng, Xiao-dong; Li, Wei; Jiang, Ming-shun

2017-09-01

Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating (FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform (PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm (GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.

Fiber Bragg Grating vibration sensor with DFB laser diode

NASA Astrophysics Data System (ADS)

Siska, Petr; Brozovic, Martin; Cubik, Jakub; Kepak, Stanislav; Vitasek, Jan; Koudelka, Petr; Latal, Jan; Vasinek, Vladimir

2012-01-01

The Fiber Bragg Grating (FBG) sensors are nowadays used in many applications. Thanks to its quite big sensitivity to a surrounding environment, they can be used for sensing of temperature, strain, vibration or pressure. A fiber Bragg grating vibration sensor, which is interrogated by a distributed feedback laser diode (DFB) is demonstrated in this article. The system is based on the intensity modulation of the narrow spectral bandwidth of the DFB laser, when the reflection spectrum of the FBG sensor is shifted due to the strain that is applied on it in form of vibrations caused by acoustic wave pressure from loud speaker. The sensor's response in frequency domain and strain is measured; also the factor of sensor pre-strain impact on its sensitivity is discussed.

Human Antibodies to PhtD, PcpA, and Ply Reduce Adherence to Human Lung Epithelial Cells and Murine Nasopharyngeal Colonization by Streptococcus pneumoniae

PubMed Central

Kaur, Ravinder; Surendran, Naveen; Ochs, Martina

2014-01-01

Streptococcus pneumoniae adherence to human epithelial cells (HECs) is the first step in pathogenesis leading to infections. We sought to determine the role of human antibodies against S. pneumoniae protein vaccine candidates PhtD, PcpA, and Ply in preventing adherence to lung HECs in vitro and mouse nasopharyngeal (NP) colonization in vivo. Human anti-PhtD, -PcpA, and -Ply antibodies were purified and Fab fragments generated. Fabs were used to test inhibition of adherence of TIGR4 and nonencapsulated strain RX1 to A549 lung HECs. The roles of individual proteins in adherence were tested using isogenic mutants of strain TIGR4. Anti-PhtD, -PcpA, and -Ply human antibodies were assessed for their ability to inhibit NP colonization in vivo by passive transfer of human antibody in a murine model. Human antibodies generated against PhtD and PcpA caused a decrease in adherence to A549 cells (P < 0.05). Anti-PhtD but not anti-PcpA antibodies showed a protective role against mouse NP colonization. To our surprise, anti-Ply antibodies also caused a significant (P < 0.05) reduction in S. pneumoniae colonization. Our results support the potential of PhtD, PcpA, and Ply protein vaccine candidates as alternatives to conjugate vaccines to prevent non-serotype-specific S. pneumoniae colonization and invasive infection. PMID:25245804

Chemotaxis and adherence to fungal surfaces are key components of the behavioral response of Burkholderia terrae BS001 to two selected soil fungi.

PubMed

Haq, Irshad Ul; Calixto, Renata Oliveira da Rocha; Yang, Pu; Dos Santos, Giulia Maria Pires; Barreto-Bergter, Eliana; van Elsas, Jan Dirk

2016-11-01

Burkholderia terrae BS001 has previously been proposed to be a 'generalist' associate of soil fungi, but its strategies of interaction have been largely ignored. Here, we studied the chemotactic behavior of B. terrae BS001 towards Lyophyllum sp. strain Karsten and Trichoderma asperellum 302 and the role of fungal surface molecules in their physical interaction with the bacteria. To assess the involvement of the type 3 secretion system (T3SS), wild-type strain BS001 and T3SS mutant strain BS001-ΔsctD were used in the experiments. First, the two fungi showed divergent behavior when confronted with B. terrae BS001 on soil extract agar medium. Lyophyllum sp. strain Karsten revealed slow growth towards the bacterium, whereas T. asperellum 302 grew avidly over it. Both on soil extract and M9 agar, B. terrae BS001 and BS001-ΔsctD moved chemotactically towards the hyphae of both fungi, with a stronger response to Lyophyllum sp. strain Karsten than to T. asperellum 302. The presence of a progressively increasing glycerol level in the M9 agar enhanced the level of movement. Different oxalic acid concentrations exerted varied effects, with a significantly raised chemotactic response at lower, and a subdued response at higher concentrations. Testing of the adherence of B. terrae BS001 and BS001-ΔsctD to Lyophyllum sp. strain Karsten and to cell envelope-extracted ceramide monohexosides (CMHs) revealed that CMHs in both conidia and hyphae could bind strain BS001 cells. As BS001-ΔsctD adhered significantly less to the CMHs than BS001, the T3SS was presumed to have a role in the interaction. In contrast, such avid adherence was not detected with T. asperellum 302. Thus, B. terrae BS001 shows a behavior characterized by swimming towards Lyophyllum sp. strain Karsten and T. asperellum 302 and attachment to the CMH moiety in the cell envelope, in particular of the former. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Power requirements reducing of FBG based all-optical switching

NASA Astrophysics Data System (ADS)

Scholtz, Ľubomír.; Solanská, Michaela; Ladányi, Libor; Müllerová, Jarmila

2017-12-01

Although Fiber Bragg gratings (FBGs) are well known devices, their using as all-optical switching elements has been still examined. Current research is focused on optimization of their properties for their using in future all-optical networks. The main problem are high switching intensities needed for achieving the changes of the transmission state. Over several years switching intensities have been reduced from hundreds of GW/cm2 to tens of MW/cm2 by selecting appropriate gratings and signal parameters or using suitable materials. Two principal nonlinear effects with similar power requirements can result in the bistable transmission/reflection of an input optical pulse. In the self-phase modulation (SPM) regime switching is achieved by the intense probe pulse itself. Using cross-phase modulation (XPM) a strong pump alters the FBG refractive index experienced by a weak probe pulse. As a result of this the detuning of the probe pulse from the center of the photonic band gap occurs. Using of XPM the effect of modulation instability is reduced. Modulation instability which is the main SPM degradation mechanism. We focused on nonlinear FBGs based on chalcogenide glasses which are very often used in various applications. Thanks to high nonlinear parameters chalcogenide glasses are suitable candidates for reducing switching intensities of nonlinear FBGs.

Smart Photonic Carbon Brush: FBG Length as Sensing Parameter

NASA Astrophysics Data System (ADS)

Morozov, O. G.; Nureev, I. I.; Kuznetsov, A. A.; Artemiev, V. I.

2018-04-01

This article deals with problem of carbon brush’s length measurements. There are many applications where regular inspection is not feasible because of a number of factors including, for example, time, labor, cost and disruptions due to down time. Thus, there is a need for a system that can monitor the brush’s length to calculate it’s wear rate, while the component is in operation or without removing of the component from its operational position. We propose a novel method for characterization of carbon brush’s length. This method based on the usage of advantages of the multiplicative response of FBGs and FBG arrays: spectral parameters depend on several aspects, such as grating’s period, refractive index, it’s physical length and so on. We are the first, in our point of view, who proposed to use third parameter for sensing application and prospectively all three parameters for complex measurement: the change of FBG’s length is used to measure length of the brush and it’s wear rate, grating’s central wavelength shift for temperature (due to refractive index change) and mechanical stress (due to grating’s period variations) measurements. The results of modelling and experiments are presented.

Characterization of a FBG sensor interrogation system based on a mode-locked laser scheme.

PubMed

Madrigal, Javier; Fraile-Peláez, Francisco Javier; Zheng, Di; Barrera, David; Sales, Salvador

2017-10-02

This paper is focused on the characterization of a fiber Bragg grating (FBG) sensor interrogation system based on a fiber ring laser with a semiconductor optical amplifier as the gain medium, and an in-loop electro-optical modulator. This system operates as a switchable active (pulsed) mode-locked laser. The operation principle of the system is explained theoretically and validated experimentally. The ability of the system to interrogate an array of different FBGs in wavelength and spatial domain is demonstrated. Simultaneously, the influence of several important parameters on the performance of the interrogation technique has been investigated. Specifically, the effects of the bandwidth and the reflectivity of the FBGs, the SOA gain, and the depth of the intensity modulation have been addressed.

Parallel demodulation system and signal-processing method for extrinsic Fabry-Perot interferometer and fiber Bragg grating sensors.

PubMed

Jiang, Junfeng; Liu, Tiegen; Zhang, Yimo; Liu, Lina; Zha, Ying; Zhang, Fan; Wang, Yunxin; Long, Pin

2005-03-15

A parallel demodulation system for extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) sensors is presented that is based on a Michelson interferometer and combines the methods of low-coherence interference and Fourier transform spectrum. Signals from EFPI and FBG sensors are obtained simultaneously by scanning one arm of a Michelson interferometer, and an algorithm model is established to process the signals and retrieve both the wavelength of the FBG and the cavity length of the EFPI at the same time, which are then used to determine the strain and temperature.

Strain development in curing epoxy resin and glass fibre/epoxy composites monitored by fibre Bragg grating sensors in birefringent optical fibre

NASA Astrophysics Data System (ADS)

Chehura, E.; Skordos, A. A.; Ye, C.-C.; James, S. W.; Partridge, I. K.; Tatam, R. P.

2005-04-01

Fibre Bragg gratings (FBGs) fabricated in linearly birefringent fibres were embedded in glass fibre/epoxy composites and in the corresponding unreinforced resin to monitor the effective transverse strain development during the cure process. The optical fibres containing the FBG sensors were aligned either normal or parallel to the reinforcement fibres in unidirectional glass fibre/epoxy prepregs. The chemical cure kinetics of the epoxy resin system used were studied using differential scanning calorimetry, in order to investigate the correlation between the strain monitoring results and the evolution of the curing reaction. A non-parametric cure kinetics model was developed and validated for this purpose. The effective transverse strain measured by the FBGs demonstrated high sensitivity to the degree of cure as a result of the densification of the resin caused by the curing reaction. The effective compressive transverse strain developed during the reaction, and thus the corresponding sensitivity to chemical changes, was higher in the case of the sensing fibre aligned normal to the reinforcement fibres than in the case of the sensor fibre parallel to the reinforcement fibres. Small but measurable sensitivity to cure induced changes was observed in the case of the unreinforced resin.

Pressure sensing of Fabry-Perot interferometer with a microchannel demodulated by a FBG

NASA Astrophysics Data System (ADS)

Yu, Yongqin; Chen, Xue; Huang, Quandong; Du, Chenlin; Ruan, Shuangchen

2015-07-01

A novel and compact fiber-probe pressure sensor was demonstrated based on micro Fabry-Perot interferometer (FPI). The device was fabricated by splicing both ends of a short section simplified hollow-core photonic crystal fiber (SHCPCF) with single mode fibers (SMFs), and then a micro channel was drilled by femtosecond laser micromachining in the SHC-PCF to significantly enhance the pressure sensitivity. The pressure sensing characteristics based on micro-FPI have been investigated by measuring the signals through the demodulation of phase since the external signal imposing on the interferometer will induce the phase change of interference signal. Then a FBG was cascaded to demodulate the signal. A micro FPI demonstrates a maximum pressure sensitivity of 32 dB/MPa, while a low temperature cross-sensitivity of 0.27 KPa/°C. Hence it may have potential for pressure applications in harsh environment.

Interference with the Mannose Binding and Epithelial Cell Adherence of Escherichia coli by Sublethal Concentrations of Streptomycin

PubMed Central

Eisenstein, Barry I.; Ofek, Itzhak; Beachey, Edwin H.

1979-01-01

When Escherichia coli was grown in sublethal concentrations of streptomycin, mannose binding activity and epithelial cell adherence of the E. coli cultures at stationary phase were significantly reduced in the drug-grown organisms. In a strain whose minimal inhibitory concentrations was 30 μg/ml, the percentage of reduction in mannose binding activity was dose related over a range of concentrations between 0.5 and 10 μg/ml streptomycin. Concomitant with the drug-induced suppression of mannose binding activity, antigenic and ultrastructural alterations on the surface of the drug-grown organisms were observed by agglutination tests and electron microscopy, respectively. The streptomycin effect was reversible, required actively growing organisms, and was most apparent in the early log-phase of growth. High doses of antibiotic were ineffective when added to cultures which had acquired mannose binding activity. An isogenic derivative with high-level resistance to streptomycin was obtained as a single-step mutation from the test E. coli strain. Whereas the isogenic mutant possessed mannose binding activity and adhering ability similar to the parent strain, it was resistant to the streptomycin-induced suppression of the two activities at enormous concentrations (up to 10,000 μg/ml) of streptomycin. Taken together the results suggest that the suppression of epithelial cell adherence and mannose binding activity of E. coli grown in sublethal concentrations of streptomycin is a result of classic mechanisms of drug action upon the bacterial ribosome. The results support the possibility that antibiotics may act through mechanisms other than inhibition of growth and bacterial killing to eradicate bacteria from mucosal surfaces. Images PMID:376556

Electronic monitoring of treatment adherence and validation of alternative adherence measures in tuberculosis patients: a pilot study.

PubMed

van den Boogaard, Jossy; Lyimo, Ramsey A; Boeree, Martin J; Kibiki, Gibson S; Aarnoutse, Rob E

2011-09-01

To assess adherence to community-based directly observed treatment (DOT) among Tanzanian tuberculosis patients using the Medication Event Monitoring System (MEMS) and to validate alternative adherence measures for resource-limited settings using MEMS as a gold standard. This was a longitudinal pilot study of 50 patients recruited consecutively from one rural hospital, one urban hospital and two urban health centres. Treatment adherence was monitored with MEMS and the validity of the following adherence measures was assessed: isoniazid urine test, urine colour test, Morisky scale, Brief Medication Questionnaire, adapted AIDS Clinical Trials Group (ACTG) adherence questionnaire, pill counts and medication refill visits. The mean adherence rate in the study population was 96.3% (standard deviation, SD: 7.7). Adherence was less than 100% in 70% of the patients, less than 95% in 21% of them, and less than 80% in 2%. The ACTG adherence questionnaire and urine colour test had the highest sensitivities but lowest specificities. The Morisky scale and refill visits had the highest specificities but lowest sensitivities. Pill counts and refill visits combined, used in routine practice, yielded moderate sensitivity and specificity, but sensitivity improved when the ACTG adherence questionnaire was added. Patients on community-based DOT showed good adherence in this study. The combination of pill counts, refill visits and the ACTG adherence questionnaire could be used to monitor adherence in settings where MEMS is not affordable. The findings with regard to adherence and to the validity of simple adherence measures should be confirmed in larger populations with wider variability in adherence rates.

Health monitoring system for a tall building with Fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Li, D. S.; Li, H. N.; Ren, L.; Guo, D. S.; Song, G. B.

2009-03-01

Fiber Bragg grating (FBG) sensors demonstrate great potentials for structural health monitoring of civil structures to ensure their structural integrity, durability and reliability. The advantages of applying fiber optic sensors to a tall building include their immunity of electromagnetic interference and multiplexing ability to transfer optical signals over a long distance. In the work, FBG sensors, including strain and temperature sensors, are applied to the construction monitoring of an 18-floor tall building starting from its construction date. The main purposes of the project are: 1) monitoring the temperature evolution history within the concrete during the pouring process; 2) measuring the variations of the main column strains on the underground floor while upper 18 floors were subsequently added on; and 3) monitoring the relative displacements between two foundation blocks. The FBG sensors have been installed and interrogated continuously for more than five months. Monitoring results of temperature and strains during the period are presented in the paper. Furthermore, the lag behavior between the concrete temperature and its surrounding air temperature is investigated.

Positive provider interactions, adherence self-efficacy, and adherence to antiretroviral medications among HIV infected adults: A mediation model

PubMed Central

Johnson, Mallory O.; Chesney, Margaret A.; Goldstein, Rise B.; Remien, Robert H.; Catz, Sheryl; Gore-Felton, Cheryl; Charlebois, Edwin; Morin, Stephen F.

2008-01-01

Adherence to antiretroviral (ARV) therapy for HIV infection is critical for maximum benefit from treatment and for the prevention of HIV-related complications. There is evidence that many factors determine medication adherence, including adherence self-efficacy (confidence in one's ability to adhere) and relations with health care providers. However, there are no studies that examine how these two factors relate to each other and their subsequent influence on HIV medication adherence. The goal of the current analysis was to explore a model of medication adherence in which the relationship between positive provider interactions and adherence is mediated by adherence self-efficacy. Computerized self administered and interviewer administered self reported measures of medication adherence, demographic and treatment variables, provider interactions, and adherence self-efficacy were administered to 2765 HIV infected adults on ARV. Criteria for mediation were met, supporting a model in which adherence self-efficacy is the mechanism for the relationship between positive provider interactions and adherence. The finding was consistent when the sample was stratified by gender, race, injection drug use history, and whether the participant reported receipt of HIV specialty care. Positive provider interactions may foster greater adherence self-efficacy, which is associated with better adherence to medications. Results suggest implications for improving provider interactions in clinical care, and future directions for clarifying inter-relationships among provider interactions, adherence self-efficacy, and medication adherence are supported. PMID:16623624

Combined application of FBG and PZT sensors for plantar pressure monitoring at low and high speed walking.

PubMed

Suresh, R; Bhalla, S; Singh, C; Kaur, N; Hao, J; Anand, S

2015-01-01

Clinical monitoring of planar pressure is vital in several pathological conditions, such as diabetes, where excess pressure might have serious repercussions on health of the patient, even to the extent of amputation. The main objective of this paper is to experimentally evaluate the combined application of the Fibre Bragg Grating (FBG) and the lead zirconate titanate (PZT) piezoceramic sensors for plantar pressure monitoring during walk at low and high speeds. For fabrication of the pressure sensors, the FBGs are embedded within layers of carbon composite material and stacked in an arc shape. From this embedding technique, average pressure sensitivity of 1.3 pm/kPa and resolution of nearly 0.8 kPa is obtained. These sensors are found to be suitable for measuring the static and the low-speed walk generated foot pressure. Simultaneously, PZT patches of size 10 × 10 × 0.3 mm were used as sensors, utilizing the d_{33} (thickness) coupling mode. A sensitivity of 7.06 mV/kPa and a pressure resolution of 0.14 kPa is obtained from these sensors, which are found to be suitable for foot pressure measurement during high speed walking and running. Both types of sensors are attached to the underside of the sole of commercially available shoes. In the experiments, a healthy male subject walks/runs over the treadmill wearing the fabricated shoes at various speeds and the peak pressure is measured using both the sensors. Commercially available low-cost hardware is used for interrogation of the two sensor types. The test results clearly show the feasibility of the FBG and the PZT sensors for measurement of plantar pressure. The PZT sensors are more accurate for measurement of pressure during walking at high speeds. The FBG sensors, on the other hand, are found to be suitable for static and quasi-dynamic (slow walking) conditions. Typically, the measured pressure varied from 400 to 600 kPa below the forefoot and 100 to 1000 kPa below the heel as the walking

Development of an Automated Impact Hammer for Modal Analysis of Structures

DTIC Science & Technology

2012-02-01

6 3.5 Integration with FBG interrogation system . . . . . . . . . . . . . . . . . 7 4 Experimental...distributed Fibre Bragg Gratings ( FBGs ) in optical fibres. The modified approach to SIDER has been given the name iSIDER or inverse SIDER to reflect the...response is measured at many locations using a large array of surface mounted FBG strain sensors [2]. FBGs are ideally suited to the roving response approach

Review and Analysis of Peak Tracking Techniques for Fiber Bragg Grating Sensors

PubMed Central

2017-01-01

Fiber Bragg Grating (FBG) sensors are among the most popular elements for fiber optic sensor networks used for the direct measurement of temperature and strain. Modern FBG interrogation setups measure the FBG spectrum in real-time, and determine the shift of the Bragg wavelength of the FBG in order to estimate the physical parameters. The problem of determining the peak wavelength of the FBG from a spectral measurement limited in resolution and noise, is referred as the peak-tracking problem. In this work, the several peak-tracking approaches are reviewed and classified, outlining their algorithmic implementations: the methods based on direct estimation, interpolation, correlation, resampling, transforms, and optimization are discussed in all their proposed implementations. Then, a simulation based on coupled-mode theory compares the performance of the main peak-tracking methods, in terms of accuracy and signal to noise ratio resilience. PMID:29039804

Improvement of signal to noise ratio of time domain mutliplexing fiber Bragg grating sensor network with Golay complementary codes

NASA Astrophysics Data System (ADS)

Elgaud, M. M.; Zan, M. S. D.; Abushagur, A. G.; Bakar, A. Ashrif A.

2017-07-01

This paper reports the employment of autocorrelation properties of Golay complementary codes (GCC) to enhance the performance of the time domain multiplexing fiber Bragg grating (TDM-FBG) sensing network. By encoding the light from laser with a stream of non-return-to-zero (NRZ) form of GCC and launching it into the sensing area that consists of the FBG sensors, we have found that the FBG signals can be decoded correctly with the autocorrelation calculations, confirming the successful demonstration of coded TDM-FBG sensor network. OptiGrating and OptiSystem simulators were used to design customized FBG sensors and perform the coded TDM-FBG sensor simulations, respectively. Results have substantiated the theoretical dependence of SNR enhancement on the code length of GCC, where the maximum SNR improvement of about 9 dB is achievable with the use of 256 bits of GCC compared to that of 4 bits case. Furthermore, the GCC has also extended the strain exposure up to 30% higher compared to the maximum of the conventional single pulse case. The employment of GCC in the TDM-FBG sensor system provides overall performance enhancement over the conventional single pulse case, under the same conditions.

Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors

PubMed Central

Lamberti, Alfredo; Chiesura, Gabriele; Luyckx, Geert; Degrieck, Joris; Kaufmann, Markus; Vanlanduit, Steve

2015-01-01

The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e., it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection) and modal parameter estimation techniques (Peak-Picking), some of the modes were not successfully identified. PMID:26516854

Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors.

PubMed

Lamberti, Alfredo; Chiesura, Gabriele; Luyckx, Geert; Degrieck, Joris; Kaufmann, Markus; Vanlanduit, Steve

2015-10-26

The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. Sensors 2015, 15 27175 The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e. it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection) and modal parameter estimation techniques (Peak-Picking), some of the modes were not successfully identified.

Adherence and Non-Adherence to Treatments: Focus on Pharmacy Practice in Nepal

PubMed Central

Bastakoti, Suresh; Khanal, Saval; Dahal, Bibek; Pun, Nirmala Tilija

2013-01-01

Nepal is one of the developing countries having many limitations in providing the quality health services to its population. In many countries, improvement in patients’ adherence to the pharmacotherapy had been one of major outcome of quality pharmaceutical services. Till date, very less thing has been done in this area in Nepal; so it seems mandatory to improve the patient adherence to the treatment plans. Adherence to the medical therapy can be explained by the extent of the behavioral coincidence to the medication and non-medication regimen by a patient whereas compliance and concordance are two different models of patient adherence to the therapy. Compliance model suggests that patients have been brought responsible for being unable to follow ‘doctor’s order and concordance tempts to measure the degree of agreement between patient and his or her clinician about the nature of illness and the best possible therapy for the welfare of the patient. Non-adherence to the therapy may lead to different problems as consequences of non-adherence in four different level- individual, institutional, societal and national levels. Although some programs like, “Direct Observation Treatment, Short-course (DOTS) for tuberculosis, implementation of antiretroviral treatment schedules for HIV patients and pediatric vaccination models,” are the examples of attention towards the cases of noncompliance in Nepal. It has long been faced its limitations in the forms of either untrained manpower or lack of good documentation of patients’ adherence to therapy or high illiteracy rate or unaffordibility of patients to their treatment or lack of pharmaceutical care services. PMID:23730670

Human antibodies to PhtD, PcpA, and Ply reduce adherence to human lung epithelial cells and murine nasopharyngeal colonization by Streptococcus pneumoniae.

PubMed

Kaur, Ravinder; Surendran, Naveen; Ochs, Martina; Pichichero, Michael E

2014-12-01

Streptococcus pneumoniae adherence to human epithelial cells (HECs) is the first step in pathogenesis leading to infections. We sought to determine the role of human antibodies against S. pneumoniae protein vaccine candidates PhtD, PcpA, and Ply in preventing adherence to lung HECs in vitro and mouse nasopharyngeal (NP) colonization in vivo. Human anti-PhtD, -PcpA, and -Ply antibodies were purified and Fab fragments generated. Fabs were used to test inhibition of adherence of TIGR4 and nonencapsulated strain RX1 to A549 lung HECs. The roles of individual proteins in adherence were tested using isogenic mutants of strain TIGR4. Anti-PhtD, -PcpA, and -Ply human antibodies were assessed for their ability to inhibit NP colonization in vivo by passive transfer of human antibody in a murine model. Human antibodies generated against PhtD and PcpA caused a decrease in adherence to A549 cells (P < 0.05). Anti-PhtD but not anti-PcpA antibodies showed a protective role against mouse NP colonization. To our surprise, anti-Ply antibodies also caused a significant (P < 0.05) reduction in S. pneumoniae colonization. Our results support the potential of PhtD, PcpA, and Ply protein vaccine candidates as alternatives to conjugate vaccines to prevent non-serotype-specific S. pneumoniae colonization and invasive infection. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Graphene based strain sensor with LCP substrate

NASA Astrophysics Data System (ADS)

Nie, M.; Yang, H. S.; Xia, Y. H.

2018-02-01

A flexible strain sensor constructed by an efficient, low-cost fabrication strategy is presented in this paper. It is assembled by adhering grid-like graphene on LCP substrate. Kinds of measurement setup have been designed to verify that the proposed flexible sensor device is suitable to be used in health monitoring system. From the experiment results, it can be proved that the sensor exhibits the following features: ultra-light, relatively good sensitivity, high reversibility, superior physical robustness, easy fabrication. With the great performance of this flexible strain sensor, it is considered to play an important role in body monitoring, structural health monitoring system, fatigue detection and healthcare systems in the near future.

The Fibronectin-Binding Protein Fnm Contributes to Adherence to Extracellular Matrix Components and Virulence of Enterococcus faecium

PubMed Central

Somarajan, Sudha R.; La Rosa, Sabina Leanti; Singh, Kavindra V.; Roh, Jung H.; Höök, Magnus

2015-01-01

The interaction between bacteria and fibronectin is believed to play an important role in the pathogenicity of clinically important Gram-positive cocci. In the present study, we identified a gene encoding a predicted fibronectin-binding protein of Enterococcus faecium (fnm), a homologue of Streptococcus pneumoniae pavA, in the genomes of E. faecium strain TX82 and all other sequenced E. faecium isolates. Full-length recombinant Fnm from strain TX82 bound to immobilized fibronectin in a concentration-dependent manner and also appeared to bind collagen type V and laminin, but not other proteins, such as transferrin, heparin, bovine serum albumin, mucin, or collagen IV. We demonstrated that the N-terminal fragment of Fnm is required for full fibronectin binding, since truncation of this region caused a 2.4-fold decrease (P < 0.05) in the adhesion of E. faecium TX82 to fibronectin. Deletion of fnm resulted in a significant reduction (P < 0.001) in the ability of the mutant, TX6128, to bind fibronectin relative to that of the wild-type strain; in situ reconstitution of fnm in the deletion mutant strain restored adherence. In addition, the Δfnm mutant was highly attenuated relative to TX82 (P ≤ 0.0001) in a mixed-inoculum rat endocarditis model. Taken together, these results demonstrate that Fnm affects the adherence of E. faecium to fibronectin and is important in the pathogenesis of experimental endocarditis. PMID:26371130

A magnetically actuated cellular strain assessment tool for quantitative analysis of strain induced cellular reorientation and actin alignment

NASA Astrophysics Data System (ADS)

Khademolhosseini, F.; Liu, C.-C.; Lim, C. J.; Chiao, M.

2016-08-01

Commercially available cell strain tools, such as pneumatically actuated elastomer substrates, require special culture plates, pumps, and incubator setups. In this work, we present a magnetically actuated cellular strain assessment tool (MACSAT) that can be implemented using off-the-shelf components and conventional incubators. We determine the strain field on the MACSAT elastomer substrate using numerical models and experimental measurements and show that a specific region of the elastomer substrate undergoes a quasi-uniaxial 2D stretch, and that cells confined to this region of the MACSAT elastomer substrate undergo tensile, compressive, or zero axial strain depending on their angle of orientation. Using the MACSAT to apply cyclic strain on endothelial cells, we demonstrate that actin filaments within the cells reorient away from the stretching direction, towards the directions of minimum axial strain. We show that the final actin orientation angles in strained cells are spread over a region of compressive axial strain, confirming previous findings on the existence of a varied pre-tension in the actin filaments of the cytoskeleton. We also demonstrate that strained cells exhibit distinctly different values of actin alignment coherency compared to unstrained cells and therefore propose that this parameter, i.e., the coherency of actin alignment, can be used as a new readout to determine the occurrence/extent of actin alignment in cell strain experiments. The tools and methods demonstrated in this study are simple and accessible and can be easily replicated by other researchers to study the strain response of other adherent cells.

Virulence factors of Streptococcus pyogenes strains from women in peri-labor with invasive infections.

PubMed

Golińska, E; van der Linden, M; Więcek, G; Mikołajczyk, D; Machul, A; Samet, A; Piórkowska, A; Dorycka, M; Heczko, P B; Strus, M

2016-05-01

Invasive group A streptococcal (GAS) infections constitute an important epidemiological problem. Many cases occur in women during the postnatal period. The objective of this study was to evaluate the presence of the genes responsible for production of iron-chelating protein (perR) and superantigens (speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ, and ssa) in S. pyogenes strains isolated from invasive infections in women after delivery. Furthermore, this study sought to verify whether S. pyogenes strains show special phenotypic and genotypic (sla, spy1325) characteristics that may play a decisive role in adherence to the genital tract epithelium. Moreover, the emm-types and antibiotic susceptibility were determined. We tested 30 invasive S. pyogenes strains isolated from postpartum invasive infection and 37 GAS control strains isolated from the genital tracts of asymptomatic multiparous women. The majority of the tested strains were shown to express two types of emm genes (1 and 28), though emm -12, -28, -75 and -89 were uniquely expressed in the group of strains isolated from invasive infections. A significantly higher prevalence of perR in the strains from puerperal fever was shown. Significant differences were also found between the two groups with respect to the incidence of the genes related to adherence; GAS strains originating from women with sepsis/puerperal fever showed presence of these genes less frequently than those of the control group. Although differences in frequencies of the gene coding for various superantigens were noted between the compared groups of GAS strains, they were not significant.

Non-encapsulated strains reveal novel insights in invasion and survival of Streptococcus suis in epithelial cells.

PubMed

Benga, L; Goethe, R; Rohde, M; Valentin-Weigand, P

2004-09-01

Streptococcus suis is a porcine and human pathogen causing invasive diseases, such as meningitis or septicaemia. Host cell interactions of S. suis have been studied mainly with serotype 2 strains, but multiple capsular serotypes as well as non-typeable strains exist with diverse virulence features. At present, S. suis is considered an extracellular pathogen. However, whether or not it can also invade host cells is a matter of controversial discussions. We have assessed adherence and invasion of S. suis for HEp-2 epithelial cells by comparing 10 serotype 2 strains and four non-typeable (NT) strains. Only the NT strains and a non-encapsulated serotype 2 mutant strain, but none of the serotype 2 strains, adhered strongly and were invasive. Invasion seemed to be affected by environmental signals, as suggested from comparison of strains grown in different media. Further phenotypic and genotypic characterization revealed a high diversity among the different strains. Electron microscopic analysis of invasion of selected invasive NT strains indicated different uptake mechanisms. One strain induced large invaginations comparable to those seen in 'caveolae' mediated uptake, whereas invasion of the other strains was accompanied by formation of filipodia-like membrane protrusions. Invasion of all strains, however, was similarly susceptible to hypertonic sucrose, which inhibits receptor-mediated endocytosis. Irrespective of the uptake pathway, streptococci resided in acidified phago-lysosome like vacuoles. All strains, except one, survived intracellularly as well as extracellular acidic conditions. Survival seemed to be associated with the AdiS protein, an environmentally regulated arginine deiminase of S. suis. Concluding, invasion and survival of NT strains of S. suis in epithelial cells revealed novel evidence that S. suis exhibits a broad variety of virulence-associated features depending on genetic variation and regulation.

Medication Adherence: WHO Cares?

PubMed Central

Brown, Marie T.; Bussell, Jennifer K.

2011-01-01

The treatment of chronic illnesses commonly includes the long-term use of pharmacotherapy. Although these medications are effective in combating disease, their full benefits are often not realized because approximately 50% of patients do not take their medications as prescribed. Factors contributing to poor medication adherence are myriad and include those that are related to patients (eg, suboptimal health literacy and lack of involvement in the treatment decision–making process), those that are related to physicians (eg, prescription of complex drug regimens, communication barriers, ineffective communication of information about adverse effects, and provision of care by multiple physicians), and those that are related to health care systems (eg, office visit time limitations, limited access to care, and lack of health information technology). Because barriers to medication adherence are complex and varied, solutions to improve adherence must be multifactorial. To assess general aspects of medication adherence using cardiovascular disease as an example, a MEDLINE-based literature search (January 1, 1990, through March 31, 2010) was conducted using the following search terms: cardiovascular disease, health literacy, medication adherence, and pharmacotherapy. Manual sorting of the 405 retrieved articles to exclude those that did not address cardiovascular disease, medication adherence, or health literacy in the abstract yielded 127 articles for review. Additional references were obtained from citations within the retrieved articles. This review surveys the findings of the identified articles and presents various strategies and resources for improving medication adherence. PMID:21389250

Contribution of Spores to the Ability of Clostridium difficile To Adhere to Surfaces

PubMed Central

Joshi, Lovleen Tina; Phillips, Daniel S.; Williams, Catrin F.; Alyousef, Abdullah

2012-01-01

Clostridium difficile is the commonest cause of hospital-acquired infection in the United Kingdom. We characterized the abilities of 21 clinical isolates to form spores; to adhere to inorganic and organic surfaces, including stainless steel and human adenocarcinoma cells; and to germinate. The composition of culture media had a significant effect on spore formation, as significantly more spores were produced in brain heart infusion broth (Student's t test; P = 0.018). The spore surface relative hydrophobicity (RH) varied markedly (14 to 77%) and was correlated with the ability to adhere to stainless steel. We observed no correlation between the ribotype and the ability to adhere to steel. When the binding of hydrophobic (DS1813; ribotype 027; RH, 77%) and hydrophilic (DS1748; ribotype 002; RH, 14%) spores to human gut epithelial cells at different stages of cell development was examined, DS1813 spores adhered more strongly, suggesting the presence of surface properties that aid attachment to human cells. Electron microscopy studies revealed the presence of an exosporium surrounding DS1813 spores that was absent from spores of DS1748. Finally, the ability of spores to germinate was found to be strain and medium dependent. While the significance of these findings to the disease process has yet to be determined, this study has highlighted the importance of analyzing multiple isolates when attempting to characterize the behavior of a bacterial species. PMID:22923404

Rolling motion of an elastic cylinder induced by elastic strain gradients

NASA Astrophysics Data System (ADS)

Chen, Lei; Chen, Shaohua

2014-10-01

Recent experiment shows that an elastic strain gradient field can be utilized to transport spherical particles on a stretchable substrate by rolling, inspired by which a generalized plane-strain Johnson-Kendall-Roberts model is developed in this paper in order to verify possible rolling of an elastic cylinder adhering on an elastic substrate subject to a strain gradient. With the help of contact mechanics, closed form solutions of interface tractions, stress intensity factors, and corresponding energy release rates in the plane-strain contact model are obtained, based on which a possible rolling motion of an elastic cylinder induced by strain gradients is found and the criterion for the initiation of rolling is established. The theoretical prediction is consistent well with the existing experimental observation. The result should be helpful for understanding biological transport mechanisms through muscle contractions and the design of transport systems with strain gradient.

Fatigue and fluoride corrosion on Streptococcus mutans adherence to titanium-based implant/component surfaces.

PubMed

Correa, Cassia Bellotto; Pires, Juliana Rico; Fernandes-Filho, Romeu Belon; Sartori, Rafael; Vaz, Luis Geraldo

2009-07-01

The influence of fatigue and the fluoride ion corrosion process on Streptococcus mutans adherence to commercially pure Titanium (Cp Ti) implant/component set surfaces were studied. Thirty Nobel implants and 30 Neodent implants were used. Each commercial brand was divided into three groups. Group A: control, Group B: sets submitted to fatigue (10(5) cycles, 15 Hz, 150 N), and Group C: sets submitted to fluoride (1500 ppm, pH 5.5) and fatigue, simulating a mean use of 5 years in the oral medium. Afterward, the sets were contaminated with standard strains of S. mutans (NTCC 1023) and analyzed by scanning electronic microscopy (SEM) and colony-forming unit counts (CFU/mL). By SEM, bacterial adherence was verified only in group C in both brands. By CFU/mL counts, S. mutans was statistically higher in both brands in group C than in groups A and B (p < 0.05, ANOVA). The process of corrosion by fluoride ions on Cp Ti implant/component sets allowed greater S. mutans adherence than in the absence of corrosion and with the fatigue process in isolation.

Three-axial Fiber Bragg Grating Strain Sensor for Volcano Monitoring

NASA Astrophysics Data System (ADS)

Giacomelli, Umberto; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvatore; Maccioni, Enrico; Morganti, Mauro; Orazi, Massimo; Peluso, Rosario; Sorrentino, Fiodor

2017-04-01

Fiber optic and FBGs sensors have attained a large diffusion in the last years as cost-effective monitoring and diagnostic devices in civil engineering. However, in spite of their potential impact, these instruments have found very limited application in geophysics. In order to study earthquakes and volcanoes, the measurement of crustal deformation is of crucial importance. Stress and strain behaviour is among the best indicators of changes in the activity of volcanoes .. Deep bore-hole dilatometers and strainmeters have been employed for volcano monitoring. These instruments are very sensitive and reliable, but are not cost-effective and their installation requires a large effort. Fiber optic based devices offer low cost, small size, wide frequency band, easier deployment and even the possibility of creating a local network with several sensors linked in an array. We present the realization, installation and first results of a shallow-borehole (8,5 meters depth) three-axial Fiber Bragg Grating (FBG) strain sensor prototype. This sensor has been developed in the framework of the MED-SUV project and installed on Etna volcano, in the facilities of the Serra La Nave astrophysical observatory. The installation siteis about 7 Km South-West of the summit craters, at an elevation of about 1740 m. The main goal of our work is the realization of a three-axial device having a high resolution and accuracy in static and dynamic strain measurements, with special attention to the trade-off among resolution, cost and power consumption. The sensor structure and its read-out system are innovative and offer practical advantages in comparison with traditional strain meters. Here we present data collected during the first five months of operation. In particular, the very clear signals recorded in the occurrence of the Central Italy seismic event of October 30th demonstrate the performances of our device.

Morbidly adherent placenta treatments and outcomes.

PubMed