Science.gov

Sample records for adhered fbg strain

  1. Interface strain transfer mechanism and error modification for adhered FBG strain sensor

    NASA Astrophysics Data System (ADS)

    Li, Jilong; Zhou, Zhi; Ou, Jinping

    2005-06-01

    The application of adhered FBG strain sensor is affected by interface strain transfer and error modification. In his paper, firstly, based on the characterstics of forces and damage, the fundamental hupotheses are given, and the general expression of interface transferring mechanism is derived. After that, united form of the characteristic value-λ for the general equation is geven for the multi-layer coatings. Finally, according to the error-modified equation of adhered FBG sensor, the relationships the error rate η against the shear modulus and the thckness of the glue are given. With regard to the glue applied in engineering (thickness is from 4mm to 60mm, shear modulus is from 30MPa to 200MPa), the error rate η is about 5~10%, and the correction coefficient k is about 1.05~1.11. Hence, the error modification must be considered when adhered FBG strain sensors are used in civil engineering.

  2. Strain evaluation of strengthened concrete structures using FBG sensors

    NASA Astrophysics Data System (ADS)

    Lau, Kin-tak; Zhou, Li-min; Ye, Lin

    1999-12-01

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  3. Strain evaluation of strengthened concrete structures using FBG sensors

    SciTech Connect

    Lau Kintak; Zhou Limin; Ye Lin

    1999-12-02

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  4. Strain calibration of optical FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  5. Temperature insensitive accelerometer based on a strain-chirped FBG

    NASA Astrophysics Data System (ADS)

    Zhou, Wenjun; Dong, Xinyong; Ni, Kai; Chan, C. C.; Shum, P.

    2009-10-01

    A novel accelerometer based on a strain-chirped optical fiber Bragg grating (FBG) is proposed. The FBG is glued in a slanted direction onto the lateral side of a right-angled triangle cantilever beam with a mass bonded on its free end. Vertical acceleration applied to the cantilever beam leads to a uniform bending along the beam length. As a result, the FBG is chirped and its reflection bandwidth changes linearly with the applied acceleration. A high sensitivity of 0.684 nm/g has been achieved in the experiment. This sensor is temperature insensitive, owning to the temperatureindependence nature of reflection bandwidth of the FBG.

  6. Nickel plating of FBG strain sensors for nuclear applications

    NASA Astrophysics Data System (ADS)

    Perry, Marcus; Niewczas, Pawel; Johnston, Michael; Mackersie, John

    2011-05-01

    We present a method for plating FBG strain sensors with a strongly-bonded, hermetic nickel layer, without exposure of the fiber to corrosive environments. A 1μm thick, highly adhesive chrome layer is deposited onto bare fibers via evaporation. Addition of an inert and electrically conductive gold layer then allows the fiber to be electroplated with a 50-100μm nickel layer. Finite element models have confirmed that nickel plated FBG sensors can be brazed into steel structures and used to monitor local strain and temperature. Embedding gratings that are temperature and radiation resistant will be particularly applicable to the structural health monitoring of steel prestressing tendons used in the concrete containments of nuclear power plants and other safety-significant structures.

  7. A simultaneous strain and temperature sensing module based on FBG-in-SMS

    NASA Astrophysics Data System (ADS)

    Song, Dawei; Chai, Quan; Liu, Yanlei; Jiang, Yu; Zhang, Jiangzhong; Sun, Weimin; Yuan, Libo; Canning, John; Peng, Gang-Ding

    2014-05-01

    We propose a compact multi-parameter fibre sensing module based on a fibre Bragg grating (FBG) in single-multi-single mode fibre structure (FBG-in-SMS). We experimentally demonstrated that the FBG-in-SMS can measure temperature and strain simultaneously. In addition, we found that the process of writing FBG in SMS could be an effective technique for tuning and optimizing SMS spectrum for sensing.

  8. Static FBG strain sensor with high resolution and large dynamic range by dual-comb spectroscopy.

    PubMed

    Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

    2013-05-01

    We demonstrate a fiber Bragg grating (FBG) strain sensor with optical frequency combs. To precisely characterize the optical response of the FBG when strain is applied, dual-comb spectroscopy is used. Highly sensitive dual-comb spectroscopy of the FBG enabled strain measurements with a resolution of 34 nε. The optical spectral bandwidth of the measurement exceeds 1 THz. Compared with conventional FBG strain sensor using a continuous-wave laser that requires rather slow frequency scanning with a limited range, the dynamic range and multiplexing capability are significantly improved by using broadband dual-comb spectroscopy. PMID:23669971

  9. Design and application of FBG strain experimental apparatus in high temperature

    NASA Astrophysics Data System (ADS)

    Xia, Zhongcheng; Liu, Yueming; Gao, Xiaoliang

    2014-09-01

    Fiber Bragg Grating (FBG) sensing technology has many applications, and it's widely used in detection of temperature, strain and etc. Now the application of FBG sensor is limited to the temperature below 200°C owing to the so called High Temperature Erasing Phenomenon. Strain detection over 200°C is still an engineering challenge since high temperature has a bad influence on the sensor, testing equipment and test data, etc, thus effective measurement apparatus are needed to ensure the accuracy of the measurement over 200°C, but there are no suitable FBG strain experimental apparatus in high temperature to date. In this paper a high temperature FBG strain experimental apparatus has been designed to detect the strain in high temperature. In order to verify working condition of the high temperature FBG strain, an application of FBG strain sensing experiment was given in this paper. The high temperature FBG strain sensor was installed in the apparatus, the internal temperature of experimental apparatus was controlled from -20 to 300°C accurately, and strain loading was given by the counterweight, then the data was recorded through electrical resistance strain measurement and optical sensing interrogator. Experimental data result shows that the high temperature FBG strain experimental apparatus can work properly over 200°C. The design of the high temperature FBG strain experimental apparatus are demonstrated suitable for high temperature strain gauges and FBG strain sensors , etc, which can work under the temperature of -20 ~ 300°C, the strain of -1500 ~ +1500μepsilon and the wavelength resolution of 1pm.

  10. FBG strain sensibilized monitor on railway switch pole

    NASA Astrophysics Data System (ADS)

    Li, Weilai; Liu, Jie; Pan, Jianjun; Pang, Jin; Lu, Xiaoshan; Zhou, Ciming

    2013-09-01

    Fiber Bragg Grating (FBG) sensing technology was used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, and states of loading resistance. Ring shape FBG strain gauge and strain sensibilized methods significantly increased the monitoring sensitivity. Installing approaches adapted the harsh environment in railway application. The monitoring results showed that for a Siemens S700K switch machine, its pole pressured stroke took 5s. Maximum load: -5.9kN, average load: -3.3kN. Vibration caused by resistance exists, its period: 0.1s, range: 0.5kN~1.6kN. After the stroke, the locking force was kept at -0.6kN. In tensile stroke, it also took 5s. Maximum load: 6.8kN, average load: 5.5kN. Vibration period: 0.1s, range: 0.7kN~2kN. Locking force: 0.2 kN. This long-term and on-line detecting method could meet railway switch condition monitoring demands of more than 100,000 switch machines in this country.

  11. Influence of metal bonding layer on strain transfer performance of FBG

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Chen, Weimin; Zhang, Peng; Liu, Li; Shu, Yuejie; Wu, Jun

    2013-01-01

    Metal bonding layer seriously affects the strain transfer performance of Fiber Bragg Grating (FBG). Based on the mode of FBG strain transfer, the influence of the length, the thickness, Poisson's ratio, elasticity modulus of metal bonding layer on the strain transfer coefficient of FBG is analyzed by numerical simulation. FBG is packaged to steel wire using metal bonding technology of FBG. The tensile tests of different bonding lengths and elasticity modulus are carried out. The result shows the strain transfer coefficient of FBGs are 0.9848,0.962 and their average strain sensitivities are 1.076 pm/μɛ,1.099 pm/μɛ when the metal bonding layer is zinc, whose lengths are 15mm, 20mm, respectively. The strain transfer coefficient of FBG packaged by metal bonding layer raises 8.9 percent compared to epoxy glue package. The preliminary experimental results show that the strain transfer coefficient increases with the length of metal bonding layer, decreases with the thickness of metal bonding layer and the influence of Poisson's ratio can be ignored. The experiment result is general agreement with the analysis and provides guidance for metal package of FBG.

  12. 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. PMID:26807773

  13. Life cycle strain monitoring of composite airframe structures by FBG sensors

    NASA Astrophysics Data System (ADS)

    Takahashi, I.; Sekine, K.; Kume, M.; Takeya, H.; Minakuchi, S.; Takeda, N.; Enomoto, K.

    2013-04-01

    Life cycle health monitoring technology for composite airframe structures based on strain mapping is proposed. It detects damages and deformation harmful to the structures by strain mapping using fiber Bragg grating (FBG) sensors through their life cycles including the stages of molding, machining, assembling, operation, and maintenance. In this paper, we firstly carried out a strain monitoring test of CFRP mock-up structure through the life cycle including the stage of molding, machining, assembling, and operation. The experimental result confirms that the strain which arises in each life cycle stage can be measured by FBG sensors embedded in molding stage and demonstrates the feasibility of life cycle structural health monitoring by using FBG sensors. Secondly, we conducted the strain monitoring test of CFRP scarf-repaired specimen subject to fatigue load. FBG sensors were embedded in the scarf-repaired part of the specimen and their reflection spectra were measured in uni-axial cyclic load test. Strain changes were compared with the pulse thermographic inspection. As a result, strain measured by FBG sensors changed sensitively with debonded area of repair patch, which demonstrates that the debondings of repair patches in scarf-repaired composites due to fatigue load can be detected by FBG sensors.

  14. On the use of optical fiber Bragg grating (FBG) sensor technology for strain modal analysis

    NASA Astrophysics Data System (ADS)

    Peeters, Bart; dos Santos, Fábio Luis Marques; Pereira, Andreia; Araujo, Francisco

    2014-05-01

    This paper discusses the use of optical fiber Bragg grating (FBG) strain sensors for structural dynamics measurements. For certain industrial applications, there is an interest to use strain sensors rather than or in combination with accelerometers for experimental modal analysis. Classical electrical strain gauges can be used hereto, but optical strain sensors are an interesting alternative with some very specific advantages. This paper gives an overview of dynamic strain measurements in industrial applications, discusses the benefits of FBG sensors and reviews their measurement principle. Finally, the concept of strain modal analysis is introduced and a helicopter main rotor blade vibration testing and analysis case study is presented.

  15. Life cycle structural health monitoring of airframe structures by strain mapping using FBG sensors

    NASA Astrophysics Data System (ADS)

    Takahashi, I.; Sekine, K.; Takeya, H.; Iwahori, Y.; Takeda, N.; Koshioka, Y.

    2010-04-01

    The purpose of this research is to develop the structural health monitoring system for composite airframe structures by strain mapping through their life cycles. We apply FBG sensor networks to CFRP pressure bulkheads and monitor the strain through their life cycles: molding, processing, assembly, operation and maintenance. Damages, defects and deformations which occurred in each stage are detected using the strain distribution. At first, we monitored the strain of CFRP laminates during molding and processing with FBG sensors. As a result, not only the thermal strain on curing process but also strain change due to demolding was measured precisely. In addition, we analyzed the change in strain distribution due to damages of CFRP pressure bulkhead such as stringer debonding and impact damage of skin under operational load in flight. On the basis of these results, the location of FBG sensors suitable for the detection of damages was determined.

  16. Cracking monitoring by FBG strain sensor in the small scale dam model

    NASA Astrophysics Data System (ADS)

    Ren, Liang; Li, Hongnan; Li, Dongsheng

    2009-03-01

    Accurate measurement of strain variation and effective prediction of failure within models has been a major objective for strain sensors in dam model tests. In this paper, a FBG strain sensor with enhanced strain sensitivity and packaged by two gripper tubes is presented and applied in the seismic tests of a small scale dam model. This paper discusses the principle of enhanced sensitivity of the FBG strain sensor. Calibration experiments were conducted to evaluate the sensor's strain transferring characteristics on plates of different material. This paper also investigates the applicability of the FBG strain sensors in seismic tests of a dam model by conducting a comparison between the test measurements of FBG sensors and analytical predictions, monitoring the failure progress and predicting the cracking inside the dam model. Results of the dam model tests prove that this FBG strain sensor has the advantages of small size, high precision and embedability, demonstrate promising potential in cracking and failure monitoring and in identification of the dam model.

  17. Design of an enhanced sensitivity FBG strain sensor and application in highway bridge engineering

    NASA Astrophysics Data System (ADS)

    Li, Litong; Zhang, Dongsheng; Liu, Hui; Guo, Yongxing; Zhu, Fangdong

    2014-06-01

    The theoretical design method of enhanced sensitivity fiber grating (FBG) strain sensors was given, and moreover high qualified strain sensors were developed and fabricated, whose sensing properties were good for practical applications. The strain sensor with cylindrical shell encapsulation contained three tubular structures, due to the uneven surface structure, in the area of the strain concentration, improving the sensitivity. It could achieve the embedment strain measurement and surface measurement and had the advantages of the easy installation. The good agreement was obtained between the measurements and theoretical simulation results. After each calibration test, twenty-four FBG strain sensors and six FBG temperature compensation sensors have been installed on the undersurface of the box girder of Diaoshuiyan bridge in Yongtaiwen highway. Finally, we built up a long-term structure health system for the highway bridge.

  18. Temperature-compensated strain measurement of full-scale small aircraft wing structure using low-cost FBG interrogator

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Lee, Y. G.; Park, Y.; Kim, C. G.

    2013-04-01

    Recently, health and usage monitoring systems (HUMS) are being studied to monitor the real-time condition of aircrafts during flight. HUMSs can prevent aircraft accidents and reduce inspection time and cost. Fiber Bragg grating (FBG) sensors are widely used for aircraft HUMSs with many advantages such as light weight, small size, easy-multiplexing, and EMI immunity. However, commercial FBG interrogators are too expensive to apply for small aircrafts. Generally the cost of conventional FBG interrogators is over 20,000. Therefore, cost-effective FBG interrogation systems need to be developed for small aircraft HUMSs. In this study, cost-effective low speed FBG interrogator was applied to full-scale small aircraft wing structure to examine the operational applicability of the low speed FBG interrogator to the monitoring of small aircrafts. The cost of the developed low speed FBG interrogator was about 10,000, which is an affordable price for a small aircraft. 10 FBG strain sensors and 1 FBG temperature sensor were installed on the surface of the full-scale wing structure. Load was applied to the tip of the wing structure, and the low speed interrogator detected the change in the center wavelength of the FBG sensors at the sampling rate of 10Hz. To assess the applicability of the low-cost FBG interrogator to full-scale small aircraft wing structure, a temperature-compensated strain measurement algorithm was verified experimentally under various loading conditions of the wing structure with temperature variations.

  19. Analysis, compensation, and correction of temperature effects on FBG strain sensors

    NASA Astrophysics Data System (ADS)

    Haber, T. C.; Ferguson, S.; Guthrie, D.; Graver, T. W.; Soller, B. J.; Mendez, Alexis

    2013-05-01

    One of the most common fiber optic sensor (FOS) types used are fiber Bragg gratings (FBG), and the most frequently measured parameter is strain. Hence, FBG strain sensors are one of the most prevalent FOS devices in use today in structural sensing and monitoring in civil engineering, aerospace, marine, oil and gas, composites and smart structure applications. However, since FBGs are simultaneously sensitive to both temperature and strain, it becomes essential to utilize sensors that are either fully temperature insensitive or, alternatively, properly temperature compensated to avoid erroneous measurements. In this paper, we introduce the concept of measured "total strain", which is inherent and unique to optical strain sensors. We review and analyze the temperature and strain sensitivities of FBG strain sensors and decompose the total measured strain into thermal and non-thermal components. We explore the differences between substrate CTE and System Thermal Response Coefficients, which govern the type and quality of thermal strain decomposition analysis. Finally, we present specific guidelines to achieve proper temperature-insensitive strain measurements by combining adequate installation, sensor packaging and data correction techniques.

  20. Temperature-compensated strain measurement using FBG sensors embedded in composite laminates

    NASA Astrophysics Data System (ADS)

    Tanaka, Nobuhira; Okabe, Yoji; Takeda, Nobuo

    2002-07-01

    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 (GFRP). Each material contains an FBG sensor with a different Bragg wavelength, and both ends of the device are glue to a structure. Using the difference of their Young's moduli and coefficients of thermal expansion (CTEs), both strain and temperature can be measured. The latter sensor is a laminate of two 90 degree(s) 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 were experimentally confirmed.

  1. 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.

  2. Distributed strain measurement of welded tubular joint with long gauge FBG

    NASA Astrophysics Data System (ADS)

    Murayama, H.; Kageyama, K.; Ohara, K.; Uzawa, K.; Kanai, M.; Igawa, H.

    2008-04-01

    Strain along a welded joint submitted to a load can fluctuate because of inhomogeneity in thickness or residual stress distributions and defects. Inversely, strain fluctuation may represent such inhomogeneities or defects. We applied the distributed strain sensing technique with a long gauge FBG to monitoring strain distributions along a welded tubular joint of a steel pipe. By using this sensing technique, we can measure a strain distribution at an arbitrary position along a FBG with the high spatial resolution less than 1 mm. In the tensile test of the steel pipe, we could successfully measure the strain distribution along the weld line of about 100 mm in length. We also observed the strain fluctuating sharply in some areas and acoustic emissions were simultaneously detected by the other sensors. In some areas where sharp fluctuations occurred, defects were observed by also computer tomography carried out after the tensile test. Applications for the sensing technique include health monitoring for other joint configurations, such as fastening and bonding.

  3. Life cycle strain mapping of composite airframe structures by using FBG sensors

    NASA Astrophysics Data System (ADS)

    Sekine, K.; Takahashi, I.; Kume, M.; Takeya, H.; Iwahori, Y.; Minakuchi, S.; Takeda, N.; Koshioka, Y.

    2011-04-01

    The objective of this work is to develop a system for monitoring the structural integrity of composite airframe structures by strain mapping over the entire lifecycle of the structure. Specifically, we use fiber Bragg grating sensors to measure strain in a pressure bulkhead made of carbon fiber reinforced plastics (CFRPs) through a sequence of lifecycle stages (molding, machining, assembly, operation and maintenance) and detect the damage, defects, and deformation that occurs at each stage from the obtained strain distributions. In previous work, we have evaluated strain monitoring at each step in the FRP molding and machining stages of the lifecycle. In the work reported here, we evaluate the monitoring of the changes in strain that occur at the time of bolt fastening during assembly. The results show that the FBG sensors can detect the changes in strain that occur when a load is applied to the structure during correction of thermal deformation or when there is an offset in the hole position when structures are bolted together. We also conducted experiments to evaluate the detection of damage and deformation modes that occur in the pressure bulkhead during operation. Those results show that the FBG sensors detect the characteristic changes in strain for each mode.

  4. Modal macro-strain vector based damage detection methodology with long-gauge FBG sensors

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Liu, Chongwu W.; Masri, Sami F.

    2009-07-01

    Advances in optic fiber sensing technology provide easy and reliable way for the vibration-based strain measurement of engineering structures. As a typical optic fiber sensing techniques with high accuracy and resolution, long-gauge Fiber Bragg Grating (FBG) sensors have been widely employed in health monitoring of civil engineering structures. Therefore, the development of macro strain-based identification methods is crucial for damage detection and structural condition evaluation. In the previous study by the authors, a damage detection algorithm for a beam structure with the direct use of vibration-based macro-strain measurement time history with neural networks had been proposed and validated with experimental measurements. In this paper, a damage locating and quantifying method was proposed using modal macrostrain vectors (MMSVs) which can be extracted from vibration induced macro-strain response measurement time series from long-gage FBG sensors. The performance of the proposed methodology for damage detection of a beam with different damage scenario was studied with numerical simulation firstly. Then, dynamic tests on a simply-supported steel beam with different damage scenarios were carried out and macro-strain measurements were employed to detect the damage severity. Results show that the proposed MMSV based structural identification and damage detection methodology can locate and identify the structural damage severity with acceptable accuracy.

  5. 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

    2005-05-01

    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.

  6. 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.

  7. 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.

  8. Longitudinal force measurement in continuous welded rail with bi-directional FBG strain sensors

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Xie, Kaize; Shao, Liyang; Yan, Lianshan; Xu, Jingmang; Chen, Rong

    2016-01-01

    In this work, a new method has been proposed to accurately determine longitudinal force measurement in continuous welded rail (CWR) with bi-directional fiber Bragg grating (B-FBGs) strain sensors (vertically and longitudinally installed according to the axis of rail). The response of B-FBGs has been theoretically analyzed by binding on CWR under different restrained conditions, where the coefficient of strain sensitivity of FBG is calibrated by its temperature sensitivity. Then the proposed sensor structure has been installed at two elaborately selected points on the subgrade on a Chinese high-speed railway in field. The experiment lasts for about 23 h. During the experiment, the rail temperature varied by about 7.8 °C and the differentials of relative value of wavelength change of B-FBGs of two points were 1.7850 × 10-5 and 1.4969 × 10-5. The maximum difference between the experimental and theoretical results is 13.8 kN. The experimental results agree with the theoretical analysis very well. To guarantee the measurement accuracy of over 95%, the ratio of strain sensitivity coefficients of two FBG sensors of B-FBGs structure at one test point shall be within 0.78 ˜ 1.22.

  9. Research on the FBG strain gauge used for the safety monitoring of high-temperature pressure pipes

    NASA Astrophysics Data System (ADS)

    Cai, Qing-mu; Liu, Yue-ming; He, Zheng-yan; Chen, Zhong-you; Huang, Chang-qing; Lou, Jun; Tian, Wei-jian

    2012-10-01

    High temperature pressure pipes were widely used in the chemical, oil companies and power plants, but the pipe burst incidents occurred from time to time, which had caused some damages on people's lives and property. Thus, in this paper, with the aim to solve this problem, a FBG (FBG: Fiber Bragg Grating) strain gauge structure which consists of three FBGs is designed and fabricated based on the theoretical strain and stress analysis. The strain gauge can be used for the real-time surface strain monitoring of high temperature pressure pipes. In the strain gauge, the elastic hightemperature alloy(10MoWVNb) is chosen as the substrate. The three FBGs with a similar performance are fabricated on the substrate with the high-temperature glue. Among the three FBGs, FBG1 is used for the horizontal strain sensing of high temperature pressure pipes., FBG2 is used for the longitudinal strain of high temperature pressure pipes, and FGB3 is used for temperature compensation. The strain gauge has a feature of high temperature resistance, temperature compensation and two-dimensional strain measurement. The experiment result shows that : the sensing ranges of temperature is 0~300°C, the transverse strain sensitivity is 1.110nm/μɛ, the temperature sensitivity is 0.0213nm/°C; The longitudinal strain sensitivity is 1.104nm/μɛ, the temperature sensitivity is 0.0212nm/°C; the temperature sensitivity is 0.0103nm/°C. Therefore, the strain gauge can meet the needs of the high temperature and pressure pipes.

  10. 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.

  11. Correlation-based methods in calibrating an FBG sensor with strain field non-uniformity

    NASA Astrophysics Data System (ADS)

    Cieszczyk, S.

    2015-12-01

    Fibre Bragg gratings have many sensing applications, mainly for measuring strain and temperature. The physical quantity that influences grating uniformly along its length causes a related shift of the Bragg wavelength. Many peak detection algorithms have been proposed, among which the most popular are the detection of maximum intensity, the centroid detection, the least square method, the cross-correlation, auto-correlation and fast phase correlation. Nonuniform gratings elongation is a cause of spectrum deformation. The introduction of non-uniformity can be intentional or appear as an unintended effect of placing sensing elements in the tested structure. Heterogeneous impacts on grating may result in additional errors and the difficulty in tracking the Bragg wavelength based on a distorted spectrum. This paper presents the application of correlation methods of peak wavelength shifts estimation for non-uniform Bragg grating elongation. The autocorrelation, cross-correlation and fast phase correlation algorithms are considered and experimental spectra measured for axisymmetric strain field along the Bragg grating are analyzed. The strain profile consists of constant and variable components. The results of this study indicate the properties of correlation algorithms applied to moderately non-uniform elongation of an FBG sensor.

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

    PubMed

    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

  13. Thermal characterization of FBG strain gauges for the monitoring of the cupola of Duomo di Milano

    NASA Astrophysics Data System (ADS)

    Cigada, Alfredo; Comolli, Lorenzo; Giussani, Alberto; Roncoroni, Fabio; Zenucchi, Fabio

    2011-05-01

    The incoming restoration works of Duomo di Milano main spire requires a continuous structural health monitoring of the cupola supporting it. For reasons mainly connected to the lightning hazard, fiber optic sensors have been selected, based on FBG technology. Strain of the lower part of the vaulting-rigs inside the octagonal cupola is the measurement of interest. Being the expected signals very small and the thermal disturbances very important, a thermal characterization of two types of commercial strain gauges was carried out in laboratory with a thermal chamber and a block of the same marble used for the Duomo construction. This allowed to find a relationship later used to compensate any thermal effects, leading to the extraction of the mechanical load contribution only. An uncertainty analysis gave a result of 5 to 10 μm/m in the tested temperature range -5 °C to +40 °C. The future work will expand the monitoring system to more measurement points and it is expected this can provide an important diagnostic tool during restoration operations.

  14. 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

  15. Application of an ultra-high-resolution FBG strain sensor for crustal deformation measurements at the Aburatsubo Bay, Japan

    NASA Astrophysics Data System (ADS)

    Tokunaga, T.; Liu, Q.; He, Z.; Mogi, K.; Matsui, H.; Wang, H. F.; Kato, T.

    2011-12-01

    For crustal deformation measurements, high-resolution strain sensors on the order of tens of nano-strains are desirable. Current sensors for this purpose include quartz-tube extensometers, free-space laser interferometers, and borehole strainmeters. The former two sensors show quite high strain resolution, however, these are large in size, from tens to hundreds of meter long, and hence, are difficult to measure spatial strain distribution. The optical fiber strain sensors have advantages of multiplexing capability and relatively low cost, and are widely adopted in the applications for structural health monitoring of civil structures such as bridges and buildings. Thus, as long as the strain resolution can be high enough to meet the requirement of crustal deformation measurements, fiber strain sensors can be an attractive tool. We have been developing an ultra-high strain-resolution fiber Bragg grating (FBG) sensor for static strain measurement, interrogated by a narrow line-width tunable laser. The sensor consists of a pair of FBGs, one for strain sensing and the other for temperature compensation. The Bragg wavelength difference between the two FBGs is evaluated using a cross-correlation algorithm. We already demonstrated that an ultra-high resolution corresponding to 2.6 nano-strain was obtained in the case where no strain was applied to the sensor, which was considered to be the ultimate performance of our measurement system. By directly applying variable strains to the developed sensor with a piezo-stage, a resolution of 17.6 nano-strain was demonstrated. This time, the sensor was installed into the vault at Aburatsubo, Japan, to measure crustal deformation caused by ocean tide, and the measured data were compared with the results obtained by a quartz-tube extensometer at the site, which has been measured by the University of Tokyo's Earthquake Research Institute. The deformation induced by oceanic tide was measured by the FBG sensor with the resolution about

  16. 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.

  17. 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. PMID:25968039

  18. Dynamic strain distribution measurement and crack detection of an adhesive-bonded single-lap joint under cyclic loading using embedded FBG

    NASA Astrophysics Data System (ADS)

    Ning, Xiaoguang; Murayama, Hideaki; Kageyama, Kazuro; Wada, Daichi; Kanai, Makoto; Ohsawa, Isamu; Igawa, Hirotaka

    2014-10-01

    In this study, the dynamic strain distribution measurement of an adhesive-bonded single-lap joint was carried out in a cyclic load test using a fiber Bragg grating (FBG) sensor embedded into the adhesive/adherend interface along the overlap length direction. Unidirectional carbon fiber reinforced plastic (CFRP) substrates were bonded by epoxy resin to form the joint, and the FBG sensor was embedded into the surface of one substrate during its curing. The measurement was carried out with a sampling rate of 5 Hz by the sensing system, based on the optical frequency domain reflectometry (OFDR) throughout the test. A finite element analysis (FEA) was performed for the measurement evaluation using a three-dimensional model, which included the embedded FBG sensor. The crack detection method, based on the longitudinal strain distribution measurement, was introduced and performed to estimate the cracks that occurred at the adhesive/adherend interface in the test.

  19. 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. PMID:25831344

  20. 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

  1. 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

    2015-01-01

    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

  2. Performance of a Distributed Simultaneous Strain and Temperature Sensor Based on a Fabry-Perot Laser Diode and a Dual-Stage FBG Optical Demultiplexer

    PubMed Central

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

    2013-01-01

    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. PMID:24284773

  3. 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.

  4. Measurement of compressive and tensile strain in the railway structures with FBG sensor packages

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Soo; Kim, Young-Jin; Nam, Soon-Sung; Kwon, Hyung-seok

    2009-03-01

    For monitoring of railway structures, optical fiber sensors are very convenient. The fiber sensors are very small and do not disturb the structural properties. They also have several merits such as electro-magnetic immunity, long signal transmission, good accuracy and multiplicity of one sensor line. Strain measurement technologies with fiber optic sensors have been investigated as a part of smart structure. In this paper, we investigated the possibilities of fiber optic sensor application to the monitoring of railway structures. We expect that the fiber optic sensors have much less noises than electrical strain gauges because of electro-magnetic immunity while railways operate electric power of 22000 volts. Fiber optic sensors showed good durability and long term stability for continuous monitoring of the railway structures as well as good response to the structural behaviors during construction.

  5. Design and proposal of dual line-of-defense perimeter watchdog incorporating optimally designed FBG based accelerometers and strain sensors using single optical fiber

    NASA Astrophysics Data System (ADS)

    Khan, Mohd. Mansoor; Sonkar, Ramesh Kumar

    2015-06-01

    Paper presents Opto-Mechanical intrusion sensor fence with FBGs attached to mechanical accelerometers and strain sensors, optimized on SolidWorks 2013 for desired frequency to 35 Hz, picking up accelerations/ strains and its deployment for perimeter security. The accelerometer structure consists of inertial mass supported by an L-shaped modified cantilever beam having non-uniform cross section area connected to base by a thin neck element which acts as strain concentrated centre hence an optimum zone for FBG sensors placement. Bragg wavelength shifts were obtained on Optigrating software for the obtained strain values on mechanical assembly of fence. CFD wind analysis is performed on the assembly to obtain the spot for accelerometer's placement to avoid false alarms up to wind velocities of 20 m/s.

  6. 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 Sε(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. PMID:27410147

  7. Effects of saliva or serum coating on adherence of Streptococcus oralis strains to titanium.

    PubMed

    Dorkhan, Marjan; Chávez de Paz, Luis E; Skepö, Marie; Svensäter, Gunnel; Davies, Julia R

    2012-02-01

    The use of dental implants to treat tooth loss has increased rapidly over recent years. 'Smooth' implants showing high long-term success rates have successively been replaced by implants with rougher surfaces, designed to stimulate rapid osseointegration and promote tissue healing. If exposed in the oral cavity, rougher surfaces may promote bacterial adhesion leading to formation of microbial biofilms which can induce peri-implant inflammation. Streptococcus oralis is an early colonizer of oral surfaces and has been recovered from titanium surfaces in vivo. The purpose of this study was to examine the adherence of clinical strains of S. oralis to titanium with smooth or moderately rough surface topography and to determine the effect of a saliva- or serum-derived coating on this process. Adherence was studied using a flow-cell system with confocal laser scanning microscopy, while putative adhesins were analysed using proteomics of bacterial cell wall proteins. This showed that adherence to moderately rough surfaces was greater than to smooth surfaces. Serum did not promote binding of any of the studied S. oralis strains to titanium, whereas a saliva coating increased adherence in two of three strains tested. The higher level of adherence to the moderately rough surfaces was maintained even in the presence of a saliva coating. The S. oralis strains that bound to saliva expressed an LPXTG-linked protein which was not present in the non-adherent strain. Thus strains of S. oralis differ in their capacity to bind to saliva-coated titanium and we propose that this is due to differential expression of a novel adhesin. PMID:22075030

  8. Diaphragm based high sensitive FBG pressure sensor

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    A high sensitive pressure sensor based on Fiber Bragg grating (FBG) integrated with a thin metal diaphragm was designed and demonstrated. To enhance the pressure sensitivity FBG is firmly glued across the diameter of the diaphragm. Under pressure, the diaphragm deforms and produces an induced strain along the length of the fiber causes shift in Bragg wavelength of the FBG. Pressure measurement is made by measuring the Bragg wavelength shift against change in pressure. The sensor was tested up to the maximum pressure of 140 psi and the corresponding pressure sensitivity was found to be 0.0204 nm/psi, which is approximately 970 times higher than that can be achieved with a bare FBG. The experimental results show good agreement with the theoretical results and possess good linearity and repeatability. This sensor can be used for the measurement of medium pressure, liquid level and depth of underwater.

  9. 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

  10. Debonding monitoring of composite repair patches using embedded small-diameter FBG sensors

    NASA Astrophysics Data System (ADS)

    Takeda, S.; Yamamoto, T.; Okabe, Y.; Takeda, N.

    2007-06-01

    Small-diameter fiber Bragg grating (FBG) sensors were applied to the debonding monitoring of composite repair patches. The target of the monitoring consists of carbon fiber reinforced plastic (CFRP) patches and an aluminum substrate. The specimens were prepared through simple means: the tabular patches adhered to both sides of the aluminum substrate using epoxy adhesive films. Under cyclic loading conditions, the debonding progressed between the aluminum substrate and the adhesive layers. Before the embedding of the FBG sensors, the embedding location was determined using the calculation of the sensor signals, also called the reflection spectra. When the cyclic loading was stopped at a pre-determined numbers of cycles, the reflection spectra were measured at stress conditions of both 0 and 200 MPa. The newly appearing peak in the reflection spectrum indicated the arrival of debonding at the FBG sensors. As the debonding length increased, the intensity of the peak was found to increase. The relationship between the spectral change and the debonding length was verified by the simulated spectra and the strain distributions calculated by finite element (FE) analysis. As a result, the debonding length could be evaluated quantitatively by the spectral changes in the FBG sensors.

  11. [Ability of Staphylococcus cohnii strains to adhere to epithelial cells and solid surfaces in the hospital environment].

    PubMed

    Waldon, Edyta; Szewczyk, Eligia M

    2002-01-01

    Presented study describes abilities of staphylococci to adhere to exfoliated cheek and uroepithelial epithelium cells and to various surfaces such as plastics, glass and steel. The subject of the study were strains of Staphylococcus cohnii ssp. cohnii and Staphylococcus cohnii ssp. urealyticus isolated from Intensive Care Unit of Pediatric Hospital. Staphylococcus cohnii ssp.cohnii adhered in great number to epithelial cells. However, the adhesion differed by individual strains. We did not find relationship between slime production and adherence to epithelial cell. Most of investigated strains adhered closely to surfaces--especially of plastics and glass. This phenomenon was stronger in the presence of culture medium and phosphate buffer. PMID:12185691

  12. Anaerobic induction of adherence to laminin in Lactobacillus gasseri strains by contact with solid surface.

    PubMed

    Horie, Masanori; Murakami, Takatomo; Sato, Takumi; Tarusawa, Yukiko; Nakamura, Shingo; Toba, Takahiro

    2005-10-01

    The effect of growth conditions on adhesion was studied in six species belonging to Lactobacillus acidophilus homology groups. Namely, 17 strains including 6 fresh isolates of L. gasseri from human feces were assessed for their adherence to immobilized fibronectin, laminin, and type IV collagen. These extracellular matrix proteins were used as a model of damaged intestinal mucosa. When the bacteria were grown on MRS agar under anaerobic conditions, all eight L. gasseri strains and one L. johnsonii strain showed strong adhesiveness to laminin, but not when grown in static MRS broth. A similar pattern was observed in four L. gasseri strains in terms of adherence to fibronectin. No L. gasseri or L. johnsonii strains exhibited adhesion to type IV collagen under either growth condition. Adhesion of L. acidophilus, L. crispatus, L. amylovorus, and L. gallinarum was not affected by the growth conditions. Although protease treatment of L. gasseri cells abolished the adhesion, periodate oxidation of the cells increased it except in one strain. The adherence of L. gasseri cells was diminished by periodate and alpha-mannosidase treatments of immobilized laminin. The above results suggest that mannose-specific proteinaceous adhesion can be induced in L. gasseri by contact with a mucosal surface in the anaerobic intestinal lumen. PMID:16086101

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

    SciTech Connect

    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 statistically 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.

  14. Antibacterial effect of the adhering human Lactobacillus acidophilus strain LB.

    PubMed Central

    Coconnier, M H; Liévin, V; Bernet-Camard, M F; Hudault, S; Servin, A L

    1997-01-01

    The spent culture supernatant of the human Lactobacillus acidophilus strain LB produces an antibacterial activity against a wide range of gram-negative and gram-positive pathogens. It decreased the in vitro viability of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. In contrast, it did not inhibit lactobacilli and bifidobacteria. The activity was heat stable and relatively sensitive to enzymatic treatments and developed under acidic conditions. The antimicrobial activity was independent of lactic acid production. Activity against S. typhimurium SL1344 infecting human cultured intestinal Caco-2 cells was observed as it was in the conventional C3H/He/oujco mouse model with S. typhimurium C5 infection and oral treatment with the LB spent culture supernatant. PMID:9145867

  15. Antibacterial effect of the adhering human Lactobacillus acidophilus strain LB.

    PubMed

    Coconnier, M H; Liévin, V; Bernet-Camard, M F; Hudault, S; Servin, A L

    1997-05-01

    The spent culture supernatant of the human Lactobacillus acidophilus strain LB produces an antibacterial activity against a wide range of gram-negative and gram-positive pathogens. It decreased the in vitro viability of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. In contrast, it did not inhibit lactobacilli and bifidobacteria. The activity was heat stable and relatively sensitive to enzymatic treatments and developed under acidic conditions. The antimicrobial activity was independent of lactic acid production. Activity against S. typhimurium SL1344 infecting human cultured intestinal Caco-2 cells was observed as it was in the conventional C3H/He/oujco mouse model with S. typhimurium C5 infection and oral treatment with the LB spent culture supernatant. PMID:9145867

  16. 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.

  17. Guided wave damage detection with PZT-FBG sensing

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoyi; Tian, Zhenhua; Lin, Bin; Yu, Lingyu

    2016-04-01

    This paper presents guided waves based damage detection by using a hybrid PZT actuator and optic fiber Bragg grating (FBG) sensors. In the hybrid sensing, a piezoelectric wafer (PZT) is used to generate incident guided waves based on the piezoelectric principle. Meanwhile, multiple fiber Bragg grating sensors (FBG) are adopted as receivers to measure the high-frequency small-strain guided waves base on the full width half maximum (FWHM) principle. If the inspected structure has damage such as hole, crack and notch, the incident guided waves will be reflected or scattered by the damage. Through multiple FBG sensors at different locations, the damage induced waves can be acquired and further processed for damage detection. In this research, two configurations are explored, the rosette and line arrangements of multiple sensors. The sensing and wave source localization on aluminum plate are demonstrated. The results show that wave source can be successfully detected by using both the FBG rosette and the FBG array.

  18. Studies on deformation/pore pressure coupling processes at Japanese URLs and the development of ultra-high resolution FBG strain sensors for rock mechanics (Invited)

    NASA Astrophysics Data System (ADS)

    Tokunaga, T.; Matsui, H.; Zuyuan, H.; Kashiwai, Y.

    2009-12-01

    with the opposite side of the fault. The transient increase of pore pressure by pumping activity is intuitively thought to be opposite in the polarity of change, however, it is interpreted to be related to the coupling process between deformation of rock masses and the change of pore pressure. Our numerical simulation supports our interpretation based on the deformation/pore pressure coupling process. This result strongly suggests that spatially high-density, high-resolution strain measurements together with pore pressure measurements in the subsurface can provide us quite exciting information on the behavior of rock mass deformation and fluid flow processes in the subsurface environments. For this purpose, we have started our new project on the development of multiplexed, high-accuracy, Fiber Bragg Grating (FBG) strain sensors for geo-engineering application. The target specifications are 10 nanostrain in strain resolution, 10 to 100 m in total length, 0.1 to 1 m in spatial resolution, and 10 to 100 in measurement points. We expect to finish this development in JFY 2011 and are hoping to deploy our sensors to both Mizunami in Japan and Homestake in US very near future.

  19. Diffusely Adhering Escherichia coli Strains Induce Attaching and Effacing Phenotypes and Secrete Homologs of Esp Proteins

    PubMed Central

    Beinke, Christina; Laarmann, Sven; Wachter, Clemens; Karch, Helge; Greune, Lilo; Schmidt, M. Alexander

    1998-01-01

    Recent epidemiological studies indicate that Escherichia coli strains which exhibit the diffuse-adherence phenotype (DAEC strains) represent a potential cause of diarrhea in infants. We investigated the interaction of DAEC strains isolated from diarrhea patients in Brazil and in Germany with epithelial cells in tissue culture. The investigated strains were identified as DAEC strains by (i) their attachment pattern, (ii) presence of genes associated with the Dr family of adhesins, and (iii) lack of genetic markers for other diarrhea-associated E. coli categories. Several clinical DAEC isolates were shown to secrete similar patterns of proteins into tissue culture medium. Protein secretion was found to be regulated by environmental parameters, namely, medium, temperature, pH, and iron concentration. DAEC strains secreting these proteins induced accumulation of actin and tyrosine-phosphorylated proteins at sites of bacterial attachment, leading to the formation of pedestals and/or extended surface structures. These changes were phenotypically similar to the attaching and effacing (A/E) lesions observed with enteropathogenic and some enterohemorrhagic E. coli strains carrying the locus of enterocyte effacement (LEE) pathogenicity island. Proteins homologous to the EspA, EspB, and EspD proteins, necessary for signal transduction events inducing A/E lesions, were identified by sequence analysis and cross-reaction of specific antibodies. However, initially nonadhering strains secreting these proteins induced signal transduction events only after prolonged infection. These results indicate that secretion of the Esp proteins alone is not sufficient for efficient signal transduction. This study further shows that some DAEC strains are likely to contain a homolog(s) of the LEE locus which may contribute to the pathogenic potential of DAEC. PMID:9453606

  20. An integrated FBG sensing system for bridge health monitoring

    NASA Astrophysics Data System (ADS)

    Sun, Ru-Jiao; Sun, Zhi; Dan, Dan-Hui; Sun, Li-Min

    2006-03-01

    Thanking to its distinguishing advantages including wavelength multiplexing capability, miniature size, high sensitivity, immunity from electro-magnetic interference and etc, the fiber Bragg grating (FBG) sensing technologies are regarded as a competent candidate for the bridge long-term health monitoring. According to the shifted Bragg wavelength of the light reflected by a fiber grating, the FBG sensors can accurately measure various physical properties such as strain, temperature, displacement, acceleration and corrosion. One special advantage of the FBG sensing technology is that only one demodulation device is required to acquire various physical properties simultaneously. Compared with the bridge health monitoring system using conventional sensors, this advantage makes the quasi-distributed sensing possible and data transmission more convenient because many FBG sensors can be connected in series by a single fiber. In this paper, an integrated FBG sensing system is presented for monitoring the physical state of a real bridge, the main-navigation channel cable-stayed bridge of the Donghai Bridge. The strain variation of two selected sections in the construction stage and during the load trial test are continuously monitored. The results of this study will supply a good guidance for the use of FBG sensors on the health monitoring of real bridges. Finally, the paper present the design and fabrication of an accelerometer based on the FBG technology for structure vibration monitoring.

  1. Strain-specific regulatory role of eukaryote-like serine/threonine phosphatase in pneumococcal adherence.

    PubMed

    Agarwal, Shivangi; Agarwal, Shivani; Pancholi, Preeti; Pancholi, Vijay

    2012-04-01

    Streptococcus pneumoniae exploits a battery of virulence factors to colonize the host. Although the eukaryote-like Ser/Thr kinase of S. pneumoniae (StkP) has been implicated in physiology and virulence, the role of its cotranscribing phosphatase (PhpP) has remained elusive. The construction of nonpolar markerless phpP knockout mutants (ΔphpP) in two pathogenic strains, D39 (type 2) and 6A-EF3114 (type 6A), indicated that PhpP is not indispensable for pneumococcal survival. Further, PhpP also participates in the regulation of cell wall biosynthesis/division, adherence, and biofilm formation in a strain-specific manner. Additionally, we provide hitherto-unknown in vitro and in vivo evidence of a physiologically relevant biochemical link between the StkP/PhpP-mediated cognate regulation and the two-component regulatory system TCS06 (RR06/HK06) that regulates the expression of the gene encoding an important pneumococcal surface adhesin, CbpA, which was found to be significantly upregulated in ΔphpP mutants. In particular, StkP (threonine)-phosphorylated RR06 bound to the cbpA promoter with high efficiency even in the absence of the HK06-responsive and catalytically active aspartate 51 residue. Together, our findings unravel the significant contributions of PhpP in pneumococcal physiology and adherence. PMID:22311926

  2. Capacity of Listeria monocytogenes Strains from the 2011 Cantaloupe Outbreak To Adhere, Survive, and Grow on Cantaloupe.

    PubMed

    Martinez, Mira Rakic; Osborne, Jason; Jayeola, Victor Oladimeji; Katic, Vera; Kathariou, Sophia

    2016-05-01

    The 2011 listeriosis outbreak attributed to whole cantaloupe involved several genetically distinct strains of serotypes 1/2a and 1/2b that had not been previously reported in invasive listeriosis outbreaks. Here we investigated the potential of strains from the 2011 cantaloupe outbreak to adhere, survive, and grow on cantaloupe rind and flesh and in juice extracted from cantaloupe at different temperatures (4, 8, and 25°C). All strains were able to adhere and grow, with ∼10-fold increases after 7 days at 4 or 8°C and after 24 h at 25°C, with a propensity for more growth on rind than on flesh or in extract. No significant differences in growth potential were noted among the different strains or between them and unrelated strains from other listeriosis outbreaks involving celery, deli meats, or hot dogs. Similarly to the cantaloupe outbreak strains, these other strains exhibited greater propensity for growth on rind than on flesh or in extract. Rinsing of cantaloupe fragments in sterile water resulted in temporary reductions of the populations by 50- to 100-fold, suggesting the potential of such washing to reduce risk if the produce is promptly consumed. The absence of marked differences in adherence or growth between the cantaloupe outbreak strains and strains from other outbreaks highlights the need to further characterize the 2011 cantaloupe outbreak strains and elucidate potential biological attributes that contributed to their implication in the outbreak. PMID:27296422

  3. Fiber Bragg grating (FBG) sensors used in coal mines

    NASA Astrophysics Data System (ADS)

    Wang, Jinyu; Liu, Tongyu; Song, Guangdong; Xie, Hongjing; Li, Lianqing; Deng, Xiaolin; Gong, Zhijie

    2014-06-01

    The fiber Bragg grating (FBG) strain sensors were used for on-line monitoring of the stress variation of the lined wall in the gateway retained along the goaf of No. 3203 coal mining face in Dongtan Mine. The results showed that the FBG strain sensor with the wide measuring range could measure the stress variation accurately during the support process of the gateway retained along the goaf and could provide the basis to further optimize the support structure and to determine the support plan of the gateway retained along the goaf. The FBG micro-seismic sensors were used in Xinglong Mine to detect the micro-seismic signal. The signals were well received and analyzed to determine the location and energy level of the source of the micro-seismic event warning. The FBG sensors and detecting system show a significant potential for micro-seismic detection and geological disasters detection.

  4. A FBG-based, temperature-insensitive vibration sensor

    NASA Astrophysics Data System (ADS)

    Zhou, Wenjun; Dong, Xinyong; Li, Lan; Ni, Kai; Jin, Yongxing

    2009-08-01

    In this paper, a novel temperature-insensitive vibration sensor based on a FBG is demonstrated. The FBG is glued in a slanted direction onto the lateral side of a right-angled triangle cantilever beam with an eccentric gear installed on its free end. Vertical vibration applied by the eccentric gear to the cantilever beam leads to a uniform bending along the beam length. As a result, the FBG is chirped and its reflection bandwidth and power change periodically with the variation of the displacement of the free end. The experimental results were compared with the data of vibration measurement of a conventional electrical strain sensor. Furthermore, this sensor is temperature insensitive, owning to the temperatureindependence nature of reflection bandwidth and power of the FBG.

  5. 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. PMID:26382558

  6. Design and development of high-temperature sensor using FBG

    NASA Astrophysics Data System (ADS)

    Venkata Reddy, M.; Srimannarayana, K.; V. Apparao, T.; Sai Shankar, M.

    2015-08-01

    A novel sensor for high-temperature measurement using Fiber Bragg grating (FBG) has been designed and simulated. The sensor works based on measurement of the shift in Bragg wavelength that corresponds to the temperature induced strain by making use of a mechanical transducer. The transducing element provides temperature dependent strain on FBG by means of differential linear thermal expansion of two different ceramic materials: Alumina and Silicon Carbide. The designed sensor can measure the temperatures from 20°C to 1500°C.

  7. A tip deflection calculation method for a wind turbine blade using temperature compensated FBG sensors

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Sun; Huh, Yong-Hak; Kwon, Il-Bum; Yoon, Dong-Jin

    2012-02-01

    The tip deflections of wind turbine blades should be monitored continuously to prevent catastrophic failures of wind turbine power plants caused by blades hitting the tower. In this paper, a calculation method for wind turbine blade tip deflection is proposed using a finite difference method based on arbitrary beam bending and moment theory using measured strains. The blade strains were measured using fiber optic Bragg grating sensors. In order to confirm this method, a 100 kW composite wind turbine blade was manufactured with epoxy molded fiber optic Bragg grating (FBG) sensors installed in the shear web of the blade. A number of these sensors, normal FBG probes, were fabricated to only measure strains and the other sensors, temperature compensated FBG probes, were prepared to also measure strain and temperature. Because the output signals of FBG sensors are dependent on strains as well as temperatures, the sensor output signals should be compensated by the temperatures to obtain accurate strains. These FBG sensors were attached on the lower and upper parts of the web at one meter intervals throughout the entire length of the blade. To evaluate the measurement accuracy of the FBG sensors, conventional electrical strain gauges were also bonded onto the surface of the web beside each FBG sensor. By performing a static load test of the blade, the calculated tip deflection of the blade was well determined within an average error of 2.25%.

  8. Prevalence of Escherichia coli strains with localized, diffuse, and aggregative adherence to HeLa cells in infants with diarrhea and matched controls.

    PubMed Central

    Gomes, T A; Blake, P A; Trabulsi, L R

    1989-01-01

    To determine the possible role of Escherichia coli strains with three different patterns of adherence to HeLa cells in causing diarrhea in infants in São Paulo, Brazil, we studied stool specimens from 100 infants up to 1 year of age with acute diarrheal illnesses and 100 age-matched control infants without recent diarrhea. E. coli with localized adherence to HeLa cells was much more common in patients (23%) than in controls (2%) (P less than 0.0001) and was detected more frequently than rotavirus (19%) was in patients, even though the study was conducted during the coldest months of the year. Most (80%) of the E. coli colonies with localized adherence were of traditional enteropathogenic E. coli serotypes. Little difference was found between patients and controls in the rate of isolation of E. coli with diffuse adherence (31 and 32%, respectively) or aggregative adherence (10 and 8%, respectively). A genetic probe used to detect a plasmid-mediated adhesin which confers expression of localized adherence proved to be 100% sensitive and 99.9% specific in detecting E. coli with localized adherence to HeLa cells. Although E. coli strains with localized adherence have now been shown to be enteric pathogens in several parts of the world, the role of strains showing diffuse adherence and aggregative adherence is still uncertain. PMID:2563383

  9. 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

    2016-01-01

    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. PMID:27618006

  10. Adherence characteristics of Listeria strains isolated from three ready-to-eat meat processing plants.

    PubMed

    Kushwaha, Kalpana; Muriana, Peter M

    2009-10-01

    Over 1,560 non-food contact surface swabs and raw meat ingredient samples were collected from three ready-to-eat meat processing plants (520 from each plant) from 1998 to 1999, resulting in the recovery of 259 isolates of Listeria obtained from postprocess areas including drains, floors, garbage bins, cart wheels, walls, equipment surfaces, tables, brooms, pallet jacks, hoses, ladders, and waste chutes. We further examined 246 of the 259 isolates for adherence phenotype and used PCR to identify those that were Listeria monocytogenes. Adherence was classified as weak, moderate, or strong depending on results obtained with all Listeria isolates by using a fluorescent microplate adherence assay. Among the 246 isolates, there were 61 weakly, 148 moderately, and 37 strongly adherent Listeria, of which 130 (53%) were found to be L. monocytogenes. Plants A and B provided similar recoveries of 39 (7.5%) and 43 (8.3%) Listeria-positive isolates, including 9 (23.1% of Listeria) and 41 (95.3% of Listeria) identified as L. monocytogenes, respectively, that were weakly or moderately adherent. In plant C, we recovered 164 Listeria-positive samples (31.5% isolation rate), which included 80 L. monocytogenes-positive samples (49.8% of Listeria spp.), 52 of which were moderately adherent, as well as all 9 strongly adherent isolates of L. monocytogenes obtained in this study. Adherence properties of Listeria may allow persistence and recurrence in plant environments, potentially increasing the chance of eventual product contamination, and this emphasizes the need for sanitary approaches to prevent colonization by Listeria as well as product antimicrobial interventions should the sanitation barrier be breached. PMID:19833036

  11. Role of M3 protein in the adherence and internalization of an invasive Streptococcus pyogenes strain by epithelial cells.

    PubMed

    Eyal, Osnat; Jadoun, Jeries; Bitler, Arcady; Skutelski, Ehud; Sela, Shlomo

    2003-10-15

    Streptococcus pyogenes utilizes multiple mechanisms for adherence to and internalization by epithelial cells. One of the molecules suggested of being involved in adherence and internalization is the M protein. Although strains of the M3 serotype form the second largest group isolated from patients with severe invasive diseases and fatal infections, not much information is known regarding the interactions of M3 protein with mammalian cells. In this study we have constructed an emm3 mutant of an invasive M3 serotype (SP268), and demonstrated that the M3 protein is involved in both adherence to and internalization by HEp-2 cells. Fibronectin promoted both adherence and internalization of SP268 in an M3-independent pathway. Utilizing speB and speB/emm3 double mutants, it was found that M3 protein is not essential for the maturation of SpeB, as was reported for the M1 protein. Increased internalization efficiency observed in both the speB and emm3/speB mutants suggested that inhibition of S. pyogenes internalization by SpeB is not related to the presence of an intact M3 protein. Thus, other proteins in SP268, which serve as targets for SpeB activity, have a prominent role in the internalization process. PMID:14522456

  12. Experimental investigation of smart FRP-concrete composite beam with embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Wang, Yanlei; Hao, Qingduo; Zhou, Zhi; Ou, Jinping

    2007-07-01

    Fiber Bragg grating (FBG) sensor is broadly accepted as a structural health monitoring device for fiber reinforced polymer (FRP) materials by either embedding into or bonding onto the structures. A new kind of smart FRP-concrete composite beam was developed by using embedded FBG sensors. Firstly, fabrication process of the smart FRP-concrete composite beam was introduced. Subsequently, FRP laminates with embedded FBG sensors, which have the same stacking sequences as that of the smart composite beam, were fabricated and tested on material test system to determine the strain sensitivity coefficients of the smart composite beams. Finally, the proposed smart FRP-concrete composite beam was tested in 4-point bending to verify the operation of FBG sensors embedded in the smart beam. The experimental results indicate the strain sensing property of the laminates with embedding FBG sensors is nearly the same as that of bare FBG sensor, and the output of embedded FBG sensors in the smart beam agrees well with that of surface-bonded strain gauges over the entire load range. The proposed smart FRP-concrete composite beam can reveal the true internal strain of itself in its service life and will have wide applications for long-term monitoring in civil engineering.

  13. Progressive failure monitoring of E-glass/vinylester curve composites using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Azmi, Asrul Izam; Raju, Raju; Peng, Gang-Ding

    2012-02-01

    In this paper, we report our recent work in an application of fiber Bragg grating (FBG) sensors in progressive failure monitoring of E-glass/vinylester top-hat stiffener (THS) composites. FBG sensor arrays were embedded at strategic points within the THS to monitor the onset and progress of failure modes as the THS undergone a transverse loading. Techniques to embed FBGs in-situ during composite structure fabrication are developed. Our experiments demonstrated that key structural failure information can be obtained from the analysis and assessment of data, such as average strain, strain gradient and full spectrum measurements, collected by the embedded FBG sensors.

  14. Structural behavior of concrete box bridge using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Chung, Wonseok; Kang, Donghoon

    2012-04-01

    For the structural monitoring of railway bridges, electromagnetic interference (EMI) is a significant problem as modern railway lines are powered by high-voltage electric power feeding systems. Fiber optic sensing systems are free from EMI and have been successfully applied in civil engineering fields. This study presents the application of fiber Bragg grating (FBG)-based sensing systems to precast concrete box railway bridges. A 20 m long full-scale precast concrete box railway girder was fabricated and tested in order to identify its static performance. The experimental program involved the measurement of the nonlinear static behavior until failure. Multiplexed FBG strain sensors were embedded along the length of steel rebar and a strain-induced wavelength shift was measured in order to monitor internal strains. The measured values from the FBG-based sensors are compared with the results using electric signal-based sensors. The results show that the FBG sensing system is promising and can improve the efficiency of structural monitoring for modern railway bridges.

  15. Guidelines for the characterization and use of fibre optic sensors: basic definitions and a proposed standard for FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Habel, Wolfgang R.; Baumann, Ingolf; Berghmans, Francis; Borzycki, Krzysztof; Chojetzki, Christoph; Haase, Karl-Heinz; Jaroszewicz, Leszek R.; Kleckers, Thomas; Niklès, Marc; Rothhardt, Manfred; Schlüter, Vivien; Thévenaz, Luc; Tur, Moshe; Wuilpart, Marc

    2009-10-01

    This paper describes the outcome of two groups which are involved in the specification of guidelines for fibre optic sensors performance and testing. The "Guideline for use of fibre optic sensors" from the COST-299 guideline group, and the "Optical Strain Sensor based on Fibre Bragg Grating" from the GESA guideline group of the VDI - "The Association of German Engineers". Through appropriate specifications and definitions, both guidelines aim at enabling better understanding of fibre optic sensors characteristics and performances. A concise view into the structure of the guidelines is presented, emphasizing important aspects. The English version of the two guidelines will be available in autumn 2009.

  16. Application of FBG sensors in rolled concrete dam model

    NASA Astrophysics Data System (ADS)

    Ren, Liang; Li, Hong-Nan, Sr.; Li, Xin; Zhou, Jin; Xiang, Lianqing

    2006-03-01

    Optical fiber sensors have received increasing attention in the fields of civil engineering due to their advantages such as 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. Strain transferring characteristics was conducted in the calibration experiment on the plain concrete beam using universal testing machine. Three tube-packaged strain FBG sensors were applied in the vibration experiment of roller compacted artificial concrete dam model. The strain analysis was done with different work conditions by three dynamic loads of noise, sine wave and random wave. The different parts of roller compacted artificial concrete dams were monitored successfully in elastic strain and split strain by action of dynamic load. The results show that possible fatigue and breakage damages can be monitored conveniently by embedded FBG sensors, and information can be well provided for structure health diagnoses under the action of dynamic load.

  17. Absolute strain measurements made with fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Song, In C.; Lee, Sun K.; Jeong, Sung H.; Lee, Byeong H.

    2004-02-01

    A strain sensor system based on optical fiber Bragg gratings (FBGs) is proposed with a new matched-filter design. The strain variation on the sensor FBG is continuously followed and matched by a filter FBG by use of a feedback control loop that produces an identical strain condition on the filter FBG. The matched strain on the filter FBG is then determined from the resonance vibration of the fiber piece embedding the filter FBG. The implementation and the performance of the proposed system are described. It is demonstrated that the proposed system can distinguish strain variation on the sensor FBG with resolution of one microstrain.

  18. Ultra-compact strain- and temperature-insensitive torsion sensor based on a line-by-line inscribed phase-shifted FBG.

    PubMed

    Huang, Bo; Shu, Xuewen

    2016-08-01

    A novel temperature- and strain-independent optical fiber torsion sensor based on a phase-shifted fiber Bragg grating (PSFBG) inscribed by the line-by-line (LbL) technique in a standard single-mode fiber with a femtosecond laser has been proposed and experimentally demonstrated. The strong birefringence created by the LbL inscription technique leads to the significant polarization splitting of the transmission peak of the PSFBG. By simply monitoring the variation of the amplitude difference between the two polarization-peaks, the fiber torsion angle and the fiber torsion direction can be simultaneously deduced without temperature and strain confusion. The torsion sensor exhibits a high torsion sensitivity of up to -1032.71 dB/(rad/mm), with the distinct advantages of low manufacture cost, small dimension (just ~1.72mm), and extremely robust and simple structure, which make it very attractive for practical applications. To the best of our knowledge, this is the smallest torsion sensor ever reported. PMID:27505735

  19. Adherent invasive Escherichia coli strains from patients with Crohn's disease survive and replicate within macrophages without inducing host cell death.

    PubMed

    Glasser, A L; Boudeau, J; Barnich, N; Perruchot, M H; Colombel, J F; Darfeuille-Michaud, A

    2001-09-01

    Escherichia coli strains recovered from Crohn's disease (CD) lesions are able to adhere to and invade cultured intestinal epithelial cells. We analyzed the behavior within macrophages of adherent invasive E. coli (AIEC) strains isolated from patients with CD. All the 15 AIEC strains tested were able to replicate extensively within J774-A1 cells: the numbers of intracellular bacteria increased 2.2- to 74.2-fold at 48 h over that at 1 h postinfection. By use of murine peritoneal macrophages and human monocyte-derived-macrophages, the reference AIEC strain LF82 was confirmed to be able to survive intracellularly. Transmission electron micrographs of AIEC LF82-infected macrophages showed that at 24 h postinfection, infected cells harbored large vacuoles containing numerous bacteria, as a result of the fusion of several vacuoles occurring after 8 h postinfection. No lactate dehydrogenase (LDH) release, no sign of DNA fragmentation or degradation, and no binding to fluorescein isothlocyanate-labeled annexin V were observed with LF82-infected J774-A1 cells, even after 24 h postinfection. LF82-infected J774-A1 cells secreted 2.7-fold more tumor necrosis factor alpha (TNF-alpha) than cells stimulated with 1 microg of lipopolysaccharide (LPS)/ml. No release of interleukin-1beta was observed with LPS-prestimulated J774-A1 cells infected with AIEC LF82. These findings showed that (i) AIEC strains are able to survive and to replicate within macrophages, (ii) AIEC LF82 replication does not induce any cell death of the infected cells, and (iii) LF82-infected J774-A1 cells release high levels of TNF-alpha. These properties could be related to some features of CD and particularly to granuloma formation, one of the hallmarks of CD lesions. PMID:11500426

  20. 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.

  1. Adaptive dynamic FBG interrogation utilising erbium-doped fibre

    NASA Astrophysics Data System (ADS)

    John, R. N.; Read, I.; MacPherson, W. N.

    2013-04-01

    A dynamic fibre Bragg grating interrogation scheme is investigated using two-wave mixing in erbium-doped fibre, capable of adapting to quasistatic strain and temperature drifts. An interference pattern set up in the erbium-doped fibre creates, due to the photorefractive effect, a dynamic grating capable of wavelength demodulating the FBG signal. The presence of a dynamic grating was verified and then dynamic strain signals from a fibre stretcher were measured. The adaptive nature of the technique was successfully demonstrated by heating the FBG while it underwent dynamic straining leading to detection unlike an alternative arrayed waveguide grating system which simultaneously failed detection. Two gratings were then wavelength division multiplexed with the signal grating receiving approximately 30dB greater signal showing that there was little cross talk in the system.

  2. Actinobacillus actinomycetemcomitans strains Y4 and N27 adhere to hydroxyapatite by distinctive mechanisms.

    PubMed Central

    Kagermeier, A S; London, J

    1985-01-01

    Actinobacillus actinomycetemcomitans strains Y4 and N27 absorb to spheroidal hydroxyapatite in roughly the same numbers per milligram of substrate and with the same tenacity as two previously tested Cytophaga species. Although the two strains of A. actinomycetemcomitans exhibited similar affinities and number of binding sites for SHA, their response to enzyme treatment and heating were very different. The capacity of strain Y4 to attach to spheroidal hydroxyapatite was diminished by treatment with proteases and phospholipases and was unaffected by neuraminidase, while strain N27 was unaffected by proteases and phospholipases and lost its binding capabilities when treated with neuraminidase. Images PMID:3972445

  3. Application of the fiber Bragg grating (FBG) sensors in coal mines

    NASA Astrophysics Data System (ADS)

    Wang, Jinyu; Song, Guang-Dong; Hu, Binxin; Li, Lianqing; Liu, Tongyu

    2013-09-01

    The FBG strain sensors were applied to the Dongtan Mine to monitor the stress variation of the lined wall in the gateway retained along goaf of No. 3203 coal mining face on line. The results showed that the FBG strain sensor with high measuring range could measure the stress variation accurately during the support process of the gateway retained along goaf and could provide the basis to further optimize the support structure and to determine the support plan of the gateway retained along the goaf. The FBG micro-seismic sensors were used in Xinglong Mine to detect micro-seismic signal. The signals are well received and analyzed to determine the earthquake source and do warming. The FBG sensors and detecting system show great prospect in micro-seismic detection, and geological disasters detecting.

  4. FBG/DFB-induced chaotic self-mixing analysis and sensing applications

    NASA Astrophysics Data System (ADS)

    Tosi, Daniele

    2013-09-01

    Optical feedback induced by a highly reflective fiber Bragg grating (FBG) onto a distributed feedback (DFB) laser is investigated. In static strain conditions, the covariance matrix of the chaotic noise generated by DFB/FBG self-mixing interference is decomposed into its eigenvalues. Then, by observing the eigenvalue pattern, it is possible to detect the strain applied to FBG independently from source power and electrical noise level. Furthermore, by employing a Capon spectral estimator, and splitting and filtering out the self-mixing eigenvalues, it is possible to dynamically detect acoustic signals in harsh signal-to-noise conditions. This technique provides dual static and dynamic FBG interrogation independent on optical power and fiber link losses variations.

  5. Distributed deformation measurement of large space deployable mechanism based on FBG sensors

    NASA Astrophysics Data System (ADS)

    Dong, Yanfang; Zhou, Zude; Liu, Yi; Liu, Mingyao; Li, Ruiya; Li, Tianliang

    2015-10-01

    Space deployable mechanisms are widely used, important and multi-purpose components in aerospace fields. In order to ensure the mechanism in normal situation after unfolded, detecting the deformation caused by huge temperature difference in real-time is necessary. This paper designed a deployable mechanism setup, completed its distributed deformation measurement by means of fiber Bragg grating (FBG) sensors and BP neural network, proved the mechanism distributed strain takes place sequence and FBG sensor is capable for space deployable mechanisms deformation measuring.

  6. Thermo-optic coefficient dependent temperature sensitivity of FBG-in-SMS based sensor

    NASA Astrophysics Data System (ADS)

    Chai, Quan; Zhang, JianZhong; Yang, Jun; Canning, John; Peng, GangDing; Chen, YuJin; Yuan, LiBo

    2015-09-01

    Fiber Bragg grating in single-multi-single mode fiber structure (FBG-in-SMS) is proposed to be used as a sensor. It could realize temperature and strain measurement simultaneously because of the different responses of the different parts of the FBG-in-SMS transmission spectrum. The temperature response is decided by the thermo-optic coefficient of the multimode fiber mainly, which is focused on especially in order to optimize its performance.

  7. 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

  8. 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.

  9. 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

  10. 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. PMID:24971391

  11. Cantilever-based FBG sensor for temperature-independent acceleration measurement

    NASA Astrophysics Data System (ADS)

    Zhou, Wenjun; Dong, Xinyong; Jin, Yongxing; Zhao, Chun-Liu

    2009-11-01

    A novel accelerometer based on a strain-chirped optical fiber Bragg grating (FBG) is proposed. The FBG is glued in a slanted direction onto the lateral side of a right-angled triangle cantilever beam with a mass bonded on its free end. Vertical acceleration applied to the cantilever beam leads to a uniform bending along the beam length. As a result, the FBG is chirped and its reflection bandwidth changes linearly with the applied acceleration. A high sensitivity of 0.679 nm/g has been achieved in the experiment. The experimental results of the sensor are compared with the results of a conventional accelerometer for the dynamic measurements. This sensor is temperature insensitive, owning to the temperature-independence nature of reflection bandwidth of the FBG.

  12. Novel FBG rosette for determining impact location in thin plate-like structure

    NASA Astrophysics Data System (ADS)

    Majewska, K.; Opoka, S.; Kudela, P.; Ostachowicz, W.

    2015-07-01

    The paper consists of two interdependent parts. The first part presents numerical simulations of output response of single Fibre Bragg Grating (FBG) sensor which is driven by homogeneous deformation along sensor length. The example of such sensor is FBG sensor glued at only two points. The grating length and modulation depth of the refractive index are the critical parameters contributing to performance of the FBG sensors. Numerical analysis allowed to select an appropriate FBG sensors which will be used in the impact detection problem. In the second part of the paper a novel strain rosette with specific sensor array used in impact localisation problem is discussed and presented. The experiment was carried out on thin composite plate with the use of pulse force excitation. The method is based on estimation of principal direction of perturbed travelling wave initiated at impact point and does not use any information about wave propagation velocity.

  13. 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

  14. A Monitoring Method Based on FBG for Concrete Corrosion Cracking.

    PubMed

    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

  15. Condition monitoring of reciprocating seal based on FBG sensors

    NASA Astrophysics Data System (ADS)

    Zhao, Xiuxu; Zhang, Shuanshuan; Wen, Pengfei; Zhen, Wenhan; Ke, Wei

    2016-07-01

    The failure of hydraulic reciprocating seals will seriously affect the normal operation of hydraulic reciprocating machinery, so the potential fault condition monitoring of reciprocating seals is very important. However, it is extremely difficult because of the limitation of reciprocating motion and the structure constraints of seal groove. In this study, an approach using fiber Bragg grating (FBG) sensors is presented. Experimental results show that the contact strain changes of a reciprocating seal can be detected by FBG sensors in the operation process of the hydraulic cylinders. The failure condition of the reciprocating seal can be identified by wavelet packet energy entropy, and the center frequency of power spectrum analysis. It can provide an effective solution for the fault prevention and health management of reciprocating hydraulic rod seals.

  16. Feasibility study of detection of chatter by using FBG during boring

    NASA Astrophysics Data System (ADS)

    Zhu, P. Y.; Peng, W.; Yuan, L.; Hu, Z. J.

    2013-10-01

    A novel real-time monitoring system based on Fiber Bragg Grating (FBG) sensor has been developed to detect chatter in boring process. In the system, a boring bar with large length-to-diameter ratio (FSTUP3225R/L-16S) was the test subject. The FBG sensor was installed on the surface of the boring bar with the length of 225mm. A classical strain gauge was employed to measure the vibratory strain and compare the results with the ones from FBG sensor. The measurements were carried out using various cutting parameters to obtain the desired chatter phenomenon. The analysis of the experimental data was verified the chatter happened during the deep hole boring. Comparison between the experimental results from two kinds of sensors demonstrated that the measurement technique could be used to detect the dynamic strain, as well as the permitting one to research the method to identify boring chatter on-line be using optical fiber sensor system.

  17. Inverse thermoelastic analysis for thermal and mechanical loads identification using FBG data

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshiya; Kamimura, Yukihiro; Igawa, Hirotaka; Morino, Yoshiki

    2014-12-01

    Fiber Bragg Grating (FBG) sensors have widely been used to monitor temperature and strain distributions as a part of the structural health monitoring system. Since FBG has the sensitivity to the variations in both temperature and strain, a compensation is required to separate the strain or temperature data from the sensor output which is the shift of the grating's Bragg wavelength. The present study develops a computational inverse thermoelastic analysis method to separately identify the thermal and mechanical boundary conditions (loads) from the output of the FBG sensor. Numerical study has been made for a corrugate-core sandwich integral thermal protection system (TPS) to examine the method. The discussion is focused on the computational stability. The results reveal that the identification of the mechanical load is less stable than that of the heat flux. It is also shown that the condition number of a coefficient matrix serves as the index of the stability of the inverse analysis.

  18. Highly sensitive contact pressure measurements using FBG patch in endotracheal tube cuff

    NASA Astrophysics Data System (ADS)

    Correia, R.; Blackman, O. R.; Hernandez, F. U.; Korposh, S.; Morgan, S. P.; Hayes-Gill, B. R.; James, S. W.; Evans, D.; Norris, A.

    2016-05-01

    A method for measuring the contact pressure between an endotracheal tube cuff and the trachea was designed and developed by using a fibre Bragg grating (FBG) based optical fibre sensor. The FBG sensor is encased in an epoxy based UV-cured cuboid patch and transduces the transversely loaded pressure into an axial strain that induces wavelength shift of the Bragg reflection. The polymer patch was created by using a PTFE based mould and increases tensile strength and sensitivity of the bare fibre FBG to pressure to 2.10×10-2 nm/kPa. The characteristics of the FBG patch allow for continuous measurement of contact pressure. The measurement of contact pressure was demonstrated by the use of a 3D printed model of a human trachea. The influence of temperature on the measurements is reduced significantly by the use of a second FBG sensor patch that is not in contact with the trachea. Intracuff pressure measurements performed using a commercial manometer agreed well with the FBG contact pressure measurements.

  19. Sialidases Affect the Host Cell Adherence and Epsilon Toxin-Induced Cytotoxicity of Clostridium perfringens Type D Strain CN3718

    PubMed Central

    Li, Jihong; Sayeed, Sameera; Robertson, Susan; Chen, Jianming; McClane, Bruce A.

    2011-01-01

    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. PMID:22174687

  20. Nonintrusive FBG tube pressure transducers with high overpressure ability

    NASA Astrophysics Data System (ADS)

    Saxena, Indu F.; Hui, Kaleonui J.

    2010-04-01

    Fiber optic sensors offer several advantages over their electrical counterparts, especially for applications in hostile, spark-sensitive environments, because no electrical power is required at the sensors. In addition, the installation of fiber sensors external to fluid carrying conduits facilitates access for troubleshooting and replacement, unlike in-line diaphragm-based sensors. Furthermore, glass fiber pressure sensors have a much higher operating temperature range, which makes them more practical for flammability-prone environments. Multiple fiber Bragg grating (FBG) sensors can be multiplexed along a single fiber optic cable, as opposed to traditional resistive strain gauges, which require individual shielded metal cabling. Applications for such fiber-optic pressure detection systems include the pressure monitoring of flow in fuel lines and their pressure valves. This paper characterizes the application of FBG sensors, with remote access capability, for the nonintrusive pressure monitoring of different types of metallic pipes. We show that pressure changes smaller than one psi can be detected with a tunable diode laser-based detection system. Standard metal pipes of steel, inconel, copper-nickel alloy and titanium are characterized, and the resilience of FBG sensors to an overpressure of up to 1500 psi is demonstrated.

  1. 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.

  2. 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. PMID:26219363

  3. Genetic relatedness and virulence properties of enteropathogenic Escherichia coli strains of serotype O119:H6 expressing localized adherence or localized and aggregative adherence-like patterns on HeLa cells.

    PubMed

    Garcia, Bruna G; Ooka, Tadasuke; Gotoh, Yasuhiro; Vieira, Mônica A M; Yamamoto, Denise; Ogura, Yoshitoshi; Girão, Dennys M; Sampaio, Suely C F; Melo, Alexis Bonfim; Irino, Kinue; Hayashi, Tetsuya; Gomes, Tânia A T

    2016-05-01

    Enteropathogenic Escherichia coli (EPEC) induce attaching and effacing (A/E) lesions in enterocytes and produce the bundle-forming pilus (BFP) contributing to the localized adherence (LA) pattern formation on HeLa cells. Enteroaggregative E. coli (EAEC) produce aggregative adherence (AA) on HeLa cells and form prominent biofilms. The ability to produce LA or AA is an important hallmark to classify fecal E. coli isolates as EPEC or EAEC, respectively. E. coli strains of serotype O119:H6 exhibit an LA+ phenotype and have been considered as comprising a clonal group of EPEC strains. However, we have recently identified O119:H6 EPEC strains that produce LA and an AA-like pattern concurrently (LA/AA-like+). In this study, we evaluated the relatedness of three LA/AA-like+ and three LA+ O119:H6 strains by comparing their virulence and genotypic properties. We first found that the LA/AA-like+ strains induced actin accumulation in HeLa cells (indicative of A/E lesions formation) and formed biofilms on abiotic surfaces more efficiently than the LA+ strains. MLST analysis showed that the six strains all belong to the ST28 complex. All strains carried multiple plasmids, but as plasmid profiles were highly variable, this cannot be used to differentiate LA/AA-like+ and LA+ strains. We further obtained their draft genome sequences and the complete sequences of four plasmids harbored by one LA/AA-like+ strain. Analysis of these sequences and comparison with 37 fully sequenced E. coli genomes revealed that both O119:H6 groups belong to the E. coli phylogroup B2 and are very closely related with only 58-67 SNPs found between LA/AA-like+ and LA+ strains. Search of the draft sequences of the six strains for adhesion-related genes known in EAEC and other E. coli pathotypes detected no genes specifically present in LA/AA-like+ strains. Unexpectedly however, we found that a large plasmid distinct from pEAF is responsible for the AA-like phenotype of the LA/AA-like+ strains. Although we

  4. 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. PMID:26233456

  5. Contributions of NanI Sialidase to Caco-2 Cell Adherence by Clostridium perfringens Type A and C Strains Causing Human Intestinal Disease

    PubMed Central

    Li, Jihong

    2014-01-01

    Previous studies showed that Clostridium perfringens type D animal disease strain CN3718 uses NanI sialidase for adhering to enterocyte-like Caco-2 cells. The current study analyzed whether NanI is similarly important when type A and C human intestinal disease strains attach to Caco-2 cells. A PCR survey determined that the nanI gene was absent from typical type A food poisoning (FP) strains carrying a chromosomal enterotoxin (CPE) gene or the genetically related type C Darmbrand (Db) strains. However, the nanI gene was present in type A strains from healthy humans, type A strains causing CPE-associated antibiotic-associated diarrhea (AAD) or sporadic diarrhea (SD), and type C Pig-Bel strains. Consistent with NanI sialidase being the major C. perfringens sialidase when produced, FP and Db strains had little supernatant sialidase activity compared to other type A or C human intestinal strains. All type A and C human intestinal strains bound to Caco-2 cells, but NanI-producing strains had higher attachment levels. When produced, NanI can contribute to host cell attachment of human intestinal disease strains, since a nanI null mutant constructed in type A SD strain F4969 had lower Caco-2 cell adhesion than wild-type F4969 or a complemented strain. Further supporting a role for NanI in host cell attachment, sialidase inhibitors reduced F4969 adhesion to Caco-2 cells. Collectively, these results suggest that NanI may contribute to the intestinal attachment and colonization needed for the chronic diarrhea of CPE-associated AAD and SD, but this sialidase appears to be dispensable for the acute pathogenesis of type A FP or type C enteritis necroticans. PMID:25135687

  6. Detection and calculation of reflected spectral shifts in fiber-Bragg gratings (FBG) in polarization maintaining optical fiber

    NASA Astrophysics Data System (ADS)

    Quintana, Joel; Gonzalez, Virgilio

    2014-04-01

    Fiber-Bragg Gratings (FBG) for Structural Health Monitoring (SHM) have been studied extensively as they offer electrically passive operation, EMI immunity, high sensitivity, and multiple multiplexing schemes, as compared to conventional electricity based strain sensors. FBG sensors written in Polarization Maintaining (PM) optical fiber offer an additional dimension of strain measurement simplifying sensor implementation within a structure. This simplification however, adds complexity to the detection of the sensor's optical response to its corresponding applied strain. We propose a method that calculates spectral shifts caused by axial and traversal strains for PM FBG sensors. The system isolates the orthogonal propagating optical waves incident to the optical interrogators. The post-processing algorithm determines the wavelength shifts, and compares to a predetermined baseline then correlates the shift magnitudes to a respective strain. This exercise validates the method of optical detection and shift calculation of multi-axis sensors as an automated, integrated system.

  7. 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.

  8. Surrounding rock mass stability monitoring of underground caverns in a geomechanical model test using FBG sensors

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhu, Weishen; Zheng, Wenhua; He, Jianping

    2009-07-01

    Fiber Bragg Gratings (FBG) sensor is widely accepted as a structural stability device for all kinds of geomaterials by either embedding into or bonding onto the structures. The physical model in geotechnical engineering, which can accurately simulate the construction processes and the effects on the stability of underground caverns on basis of satisfying the similarity principles, is an actual physical entity. Due to a large number of restrained factors, a series of experiments are difficult to be carried out, in particular for how to obtain physical parameters during the experiments. Using the geo-mechanical model test of underground caverns in Shuangjiangkou Hydropower Station as a research object, the FBG sensors were mainly focused on and adopted to figure out the problem how to achieve the small displacements in the large-scale model test. The final experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like strain gages and mini-extensometers. The experimental results agree well with the numerical simulation results. In the process of building the model, it's successful to embed the FBG sensors in the physical model through making a reserved pore and adding some special glue. In conclusion, FBG sensors can effectively measure the small displacement of monitoring points in the whole process of the geomechanical 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.

  9. Serial FBG sensor network allowing overlapping spectra

    NASA Astrophysics Data System (ADS)

    Abbenseth, S.; Lochmann, S.; Ahrens, A.; Rehm, B.

    2016-05-01

    For structure or material monitoring low impact serial fiber Bragg grating (FBG) networks have attracted increasing research interest. Common sensor networks using wavelength division multiplexing (WDM) for FBG interrogation are limited in their efficiency by the spectral width of their light source, the FBG tuning range and the spectral guard bands. Overlapping spectra are strictly forbidden in this case. Applying time division multiplexing (TDM) or active resonator schemes may overcome these restrictions. However, they introduce other substantial disadvantages like signal roundtrip dependency or sophisticated control of active resonating structures. Code division multiplexing (CDM) as a means of FBG interrogation by simple autocorrelation of appropriate codes has been shown to be superior in this respect. However, it came at the cost of a second spectrometer introducing additional equalization efforts. We demonstrate a new serial FBG sensor network utilizing CDM signal processing for efficient sensor interrogation without the need of a second spectrometer and additional state of polarization (SOP) controlling components. It allows overlapping spectra even when all sensing FBGs are positioned at the same centre wavelength and it shows a high degree of insensitivity to SOP. Sequence inversed keyed (SIK) serial signal processing utilizing quasi-orthogonal balanced codes ensures simple and quick sensor interrogation with high signal-to-interference/noise ratio.

  10. Fiber Bragg grating sensors for strain monitoring of steelwork

    NASA Astrophysics Data System (ADS)

    Wang, Tao; He, Dawei; Yang, Fan; Wang, Yongsheng

    2009-11-01

    Over the last few years, fiber Bragg grating (FBG) sensors have attracted a lot of interest and they are being used in various applications. This paper describes the FBG sensors used for strain monitoring of bogie and other steelworks. FBG sensors and resistance strain gauges are set on different position of steel girder, and weight is loaded on the steel girder. Strain value of the steel girder can be caught by two kinds of sensors when weight loaded is changed. Result of experiment shows that strain value obtained by resistance strain gauges and FBG sensor is coinciding. There is a linear correlation between value of strain and the weight loaded on the steel girder. FBG sensors with different encapsulations are set on bogie by acrylic plastic materials in order to monitor its dynamic strains. When sinusoidal load with its frequency from 0.15Hz to 2Hz was set on the bogie, FBG sensor system with data sampling rate of 20Hz were used to monitoring the dynamic strains. Strain data caught by FBG sensor system can offer accurate description of dynamic strain, and value of strain provided by FBG sensor suits theoretical values well. The experimental observations show that FBG sensors can be set on steelworks easily, and can monitor both static strain and dynamic strains well.

  11. Adhering heat-killed human Lactobacillus acidophilus, strain LB, inhibits the process of pathogenicity of diarrhoeagenic bacteria in cultured human intestinal cells.

    PubMed

    Coconnier, M H; Bernet, M F; Chauvière, G; Servin, A L

    1993-12-01

    Heat-killed L. acidophilus, strain LB, was tested for its ability to adhere in vitro onto human enterocyte-like Caco-2 and muco-secreting HT29-MTX cells in culture. The heat-killed LB bacteria exhibited a high adhesive property. A diffuse pattern of adhesion was observed to the undifferentiated cells, the apical brush border of the enterocytic cells, and to the mucus layer that covered the surface of the mucus-secreting cells. The inhibitory effect of heat-killed LB organisms against the human intestinal Caco-2 cell-adhesion and cell-invasion by a large variety of diarrhoeagenic bacteria was investigated. The following dose-dependent inhibitions were obtained: (i) against the cell-association of enterotoxigenic, diffusely-adhering and enteropathogenic Escherichia coli, Listeria monocytogenes, Yersinia pseudotuberculosis, and Salmonella typhimurium; (ii) against the cell-invasion by enteropathogenic Escherichia coli, Yersinia pseudotuberculosis, Listeria monocytogenes and Salmonella typhimurium. PMID:8188996

  12. An FBG sensor interrogation technique based on a precise optical recirculating frequency shifter driven by RF signals

    NASA Astrophysics Data System (ADS)

    Wang, Zifei; Yang, Tianxin; Jia, Dongfang; Wang, Zhaoying; Sang, Mei

    2013-03-01

    Fiber Bragg grating (FBG) sensors have numerous advantages to sense multi-physical quantities such as the temperature and strain simultaneously by monitoring the shift of the returned "Bragg" wavelength resulting from changes in these quantities. Several FBG interrogation systems have been set up using photo detectors instead of an optical spectrum analyzer (OSA) to convert wavelength to time measurements. However, in those systems, it is necessary to use mechanical tuning components to generate fast-speed wavelength-swept light sources for high-precision FBG interrogation. In this paper, a low-cost and delicate wavelength-shift detection system, without any mechanical scanning parts, is proposed and demonstrated. The wavelength scanning system is a recirculating frequency shifter (RFS) which consists of an optical amplifier, an under test FBG sensor and an optical single-sideband (SSB) modulator driven by RF signals at 10 GHz. The measurement accuracy of this system is 0.08nm.

  13. FBG sensor networks for the estimation of boundary shear stress around the novel piers

    NASA Astrophysics Data System (ADS)

    Lü, Chengang; Zhang, Ruifeng; Li, Kejia; Wu, Xing; Ge, Chunfeng

    2010-10-01

    The paper reports results obtained from a field test site in structural monitoring-a "test-to-failure," measuring strain using Fiber Bragg gratings (FBGs) sensor networks on a novel drilled concrete test pier in Huaihe river zone,Anhui province,China. To undertake the study, FBG-based sensors were chosen ,metallic recoated ,steel-tube packaged , and incorporated with steel rebars in this concrete structure. The sensors were interrogated using a compact system based on wavelength-division multiplexing (WDM) and F-P scanning approach. Throughout the test, the FBG sensors were continuously monitored, the incremental increases in the strain caused by boundary shear stress could be seen. The sensors were able to follow the resulting induced changes in load of over a range in excess of 2.5M Newton just prior to failure of the pier and representing extreme levels of strain for such a novel mechanical structure. The measurements made with the FBG-based system were found to be in agreement with the changes expected in the structure, produced by the self-balanced loading applied. The study has demonstrated the successful use of FBG sensor networks used in a test of this root type pier foundation, consequently made assessment about the health and security of the highway bridge.

  14. Long-term mechanical properties of smart cable based on FBG desensitized encapsulation sensors

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Zhou, Min

    2014-09-01

    In order to ensure the testing range and long-term reliability of the fiber Bragg grating (FBG) used for the smart cable, a smart cable embedded with FBG strain sensors based on the desensitized encapsulation structure was designed. For a smart cable specimen, the fatigue loading experiments with the cycle from 100 thousands to 2 million and 0.95 times nominal breaking cable force ( P b ) were carried out, which tested the long-serving effects of the smart cable. The test results of the static tension loading and unloading during the stepwise fatigue cycle process showed that the encapsulated FBG strain sensors had the good linearity and repeatability. Also all sensors survived after 2 million times fatigue cycle. 0.95 P b static tension test showed that the encapsulated FBG strain sensors embedded inside the cable reached 4.5% testing accuracy in the 0.86 P b working range. After 0.95 P b static tension test, the dissection test was carried out by breaking the force tension. The results showed that the appearances of the encapsulated sensors were good, and the design structures were not changed and damaged.

  15. FBG laser sensing with polarization scrambling

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjin; Kim, Daegil; Song, Minho

    2013-09-01

    We propose a laser sensor system which uses fiber Bragg gratings as laser cavity mirrors as well as sensors. With a spectrometer demodulation, a low-cost, more robust, and faster sensor functions have been demonstrated compared with the conventional wavelength-swept laser demodulation. Some of the multiple FBG sensors showed unstable lasing characteristics, leading to missing measurands. Polarization scrambling has been used to alleviate the problem. With fast polarization disturbances in the fiber-optic laser cavity, more FBG sensor outputs could be generated consistently and data acquisition rate has increased more than 5 times.

  16. Special optical fiber design to reduce reflection peak distortion of a FBG embedded in inhomogeneous material

    NASA Astrophysics Data System (ADS)

    Cheng, Lun-Kai; Toet, Peter; de Vreugd, Jan; Nieuwland, Remco; Tse, Ming-Leung Vincent; Tam, Hwayaw

    2014-03-01

    During the last decades, the use of optical fiber for sensing applications has gained increasing acceptance because of its unique properties of being intrinsically safe, unsusceptible to EMI, potentially lightweight and having a large operational temperature range. Among the different Fiber Optic sensor types, Fiber Bragg Grating (FBG) is most widely used for its unique multiplexing potential and the possibility of embedding in composite material for Structural Health Monitoring. When the fiber is embedded in an inhomogeneous environment, typically a material composed of filler and base material of different stiffness, local stiff material will generate extra lateral load to the fiber. Via the Poisson effect, this will be converted to a local axial strain. The narrow and sharp peak in the reflection spectrum of an FBG sensor relies on the constant periodicity of the grating. An inhomogeneous axial strain distribution will result in distortion or broadening of the FBG reflection spectrum. For the FBG strain sensitivity of about 1.2pm/μɛ, the spectral distortion can be disastrous for strain measurements. A fiber design to tackle this critical problem is presented. Finite Element Modeling is performed to demonstrate the effectiveness of the solution. Modeling with different configurations has been performed to verify the influence of the design. The deformation of the core in the special fiber depends on the design. For a particular configuration, the core deformation in the axial direction is calculated to be a factor of 10 lower than that of a standard fiber. The first prototype fiber samples were drawn and the manufacturing of FBG in this special fiber using the phase mask method was demonstrated successfully.

  17. Marked intra-strain variation in response of Listeria monocytogenes dairy isolates to acid or salt stress and the effect of acid or salt adaptation on adherence to abiotic surfaces.

    PubMed

    Adrião, A; Vieira, M; Fernandes, I; Barbosa, M; Sol, M; Tenreiro, R P; Chambel, L; Barata, B; Zilhao, I; Shama, G; Perni, S; Jordan, S J; Andrew, P W; Faleiro, M L

    2008-03-31

    During food processing, and particularly in cheese manufacturing processes, Listeria monocytogenes may be exposed routinely to environments of low pH or high salt concentration. It has been suggested that these environmental conditions may contribute to bacterial adherence to abiotic surfaces and increased resistance to disinfection. In this study strains isolated from the environment of artisanal cheese-making dairies were used to investigate the behaviour of L. monocytogenes in response to acid and salt stress and clear differences between strains was observed. In planktonic culture, strains varied in resistance to low pH or high NaCl concentration and in the occurrence of an adaptive response to moderate acid or NaCl. There was dislocation in responses to salt and acid. Strains resistant, or adaptive, to acid were not resistant or adaptive to NaCl. The reverse also was observed. Exposure to moderate acid did not promote adherence to polystyrene but survival, at low pH or high NaCl concentration, of cells adherent to stainless steel was increased, even for strains that had no adaptive response planktonically, but the detail of these observations varied between strains. In contrast to acid adaptation, with some strains salt adaptation enhanced adherence of L. monocytogenes to polystyrene but this was not true for all strains. For some strains salt- or acid adaptation may enhance the survival of sessile cells exposed to hypochlorite disinfection. PMID:18258322

  18. Antigen-antibody interactions: elucidation of the epitope and strain-specificity of a monoclonal antibody directed against the pilin protein adherence binding domain of Pseudomonas aeruginosa strain K.

    PubMed Central

    Wong, W. Y.; Irvin, R. T.; Paranchych, W.; Hodges, R. S.

    1992-01-01

    The C-terminal region of Pseudomonas aeruginosa strain K (PAK) pilin comprises both an epitope for the strain-specific monoclonal antibody PK99H, which blocks pilus-mediated adherence, and the adherence binding domain for buccal and tracheal epithelial cells. The PK99H epitope was located in sequence 134-140 (Asp-Glu-Gln-Phe-Ile-Pro-Lys) by using a single alanine replacement analysis on the 17-residue synthetic peptide corresponding to the PAK C-terminal sequence 128-144. Indeed, a 7-residue peptide corresponding to this sequence was shown to have a similar binding affinity to that of the native conformationally constrained (disulfide bridged) 17-residue peptide. This epitope was found to contain two critical residues (Phe137 and Lys140) and one nonessential residue (Gln136). Interestingly, the peptide, Phe-Ile-Pro-Lys, which constitutes the four most important side chains for antibody binding did not bind to PK99H. It was of interest to investigate the structural basis of the strain-specificity of PK99H utilizing naturally occurring pilin sequences. Therefore, all different residues found in the sequence corresponding to the PK99H epitope of the four other strains (PAO, CD4, K122-4, and KB7) were substituted one at a time in the PAK sequence and the changes in binding affinity of these analogs to the antibody PK99H were determined by competitive ELISA. The strain-specificity of PK99H for strains PAO, K122-4, and KB7 can be explained by the accumulated sequence changes in these strains, and at least two amino acid changes were required to explain the strain-specificity of PK99H. Similarly, cross-reactivity of PK99H with CD4 can be explained by the fact that there was only one side chain responsible for decreasing binding affinity compared to the PAK sequence. PMID:1284654

  19. Experimental testing of a self-sensing FRP-concrete composite beam using FBG sensors

    NASA Astrophysics Data System (ADS)

    Wang, Yanlei; Hao, Qingduo; Ou, Jinping

    2009-03-01

    A new kind of self-sensing fiber reinforced polymer (FRP)-concrete composite beam, which consists of a FRP box beam combined with a thin layer of concrete in the compression zone, was developed by using two embedded FBG sensors in the top and bottom flanges of FRP box beam at mid-span section along longitudinal direction, respectively. The flexural behavior of the proposed self-sensing FRP-concrete composite beam was experimentally studied in four-point bending. The longitudinal strains of the composite beam were recorded using the embedded FBG sensors as well as the surfacebonded electric resistance strain gauges. Test results indicate that the FBG sensors can faithfully record the longitudinal strain of the composite beam in tension at bottom flange of the FRP box beam or in compression at top flange over the entire load range, as compared with the surface-bonded strain gauges. The proposed self-sensing FRP-concrete composite beam can monitor its longitudinal strains in serviceability limit state as well as in strength limit state, and will has wide applications for long-term monitoring in civil engineering.

  20. Increased Rate of Apoptosis and Diminished Phagocytic Ability of Human Neutrophils Infected with Afa/Dr Diffusely Adhering Escherichia coli Strains

    PubMed Central

    Brest, Patrick; Bétis, Frédéric; Çuburu, Nicolas; Selva, Eric; Herrant, Magali; Servin, Alain; Auberger, Patrick; Hofman, Paul

    2004-01-01

    The proinflammatory effect of Afa/Dr diffusely adhering Escherichia coli (Afa/Dr DAEC) strains have been recently demonstrated in vitro by showing that polymorphonuclear leukocyte (PMN) transepithelial migration is induced after bacterial colonization of apical intestinal monolayers. The effect of Afa/Dr DAEC-PMN interaction on PMN behavior has been not investigated. Because of the putative virulence mechanism of PMN apoptosis during infectious diseases and taking into account the high level of expression of the decay-accelerating factor (DAF, or CD55), the receptor of Afa/Dr DAEC on PMNs, we sought to determine whether infection of PMNs by Afa/Dr DAEC strains could promote cell apoptosis. We looked at the behavior of PMNs incubated with Afa/Dr DAEC strains once they had transmigrated across polarized monolayers of intestinal (T84) cells. Infection of PMNs by Afa/Dr DAEC strains induced PMN apoptosis characterized by morphological nuclear changes, DNA fragmentation, caspase activation, and a high level of annexin V expression. However, transmigrated and nontransmigrated PMNs incubated with Afa/Dr DAEC strains showed similar elevated global caspase activities. PMN apoptosis depended on their agglutination, induced by Afa/Dr DAEC, and was still observed after preincubation of PMNs with anti-CD55 and/or anti-CD66 antibodies. Low levels of phagocytosis of Afa/Dr DAEC strains were observed both in nontransmigrated and in transmigrated PMNs compared to that observed with the control E. coli DH5α strain. Taken together, these data strongly suggest that interaction of Afa/Dr DAEC with PMNs may increase the bacterial virulence both by inducing PMN apoptosis through an agglutination process and by diminishing their phagocytic capacity. PMID:15385473

  1. A new deformation measurement method for heavy-duty machine tool base by multipoint distributed FBG sensors

    NASA Astrophysics Data System (ADS)

    Li, Ruiya; Tan, Yuegang; Liu, Yi; Zhou, Zude; Liu, Mingyao

    2015-10-01

    The deformation of machine tool base is one of main error elements of heavy-duty CNC machine tool. A new deformation measurement method for heavy-duty machine tool base by multipoint distributed FBG sensors is developed in this study. Experiment is implemented on a real moving beam gantry machine tool. 16 FBG strain sensors are installed on the side-surface of the machine tool base. Moving the machine tool column to different positions, varying strain signals are collected. The testing results show that this distributed measurement method based on FBG sensors can effectively detect the deformation of the machine tool base. The largest deflection in vertical direction (axis Z) can be 75μm. This work is of great significance to the structure optimizing of machine tool base and real-time error compensation of heavy-duty CNC machine tool.

  2. Deflection estimation of a wind turbine blade using FBG sensors embedded in the blade bonding line

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Woo; Kang, Woo-Ram; Jeong, Min-Soo; Lee, In; Kwon, Il-Bum

    2013-12-01

    Estimating the deflection of flexible composite wind turbine blades is very important to prevent the blades from hitting the tower. Several researchers have used fiber Bragg grating (FBG) sensors—a type of optical fiber sensor (OFS)—to monitor the structural behavior of the blades. They can be installed on the surface and/or embedded in the interior of composites. However, the typical installation positions of OFSs present several problems, including delamination of sensing probes and a higher risk of fiber breakage during installation. In this study, we proposed using the bonding line between the shear web and spar cap as a new installation position of embedded OFSs for estimating the deflection of the blades. Laboratory coupon tests were undertaken preliminarily to confirm the strain measuring capability of embedded FBG sensors in adhesive layers, and the obtained values were verified by comparison with results obtained by electrical strain gauges and finite element analysis. We performed static loading tests on a 100 kW composite wind turbine blade to evaluate its deflections using embedded FBG sensors positioned in the bonding line. The deflections were estimated by classical beam theory considering a rigid body rotation near the tip of the blade. The evaluated tip deflections closely matched those measured by a linear variable differential transformer. Therefore, we verified the capability of embedded FBG sensors for evaluating the deflections of wind turbine blades. In addition, we confirmed that the bonding line between the shear web and spar cap is a practical location to embed the FBG sensors.

  3. FBG and FOPS for local and global structural health monitoring on a single fiber

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Tjin, Swee Chuan; Ching, Wei Wen; Asundi, A.

    2015-04-01

    Fiber Bragg grating (FBG) sensors and fiber optic polarimetric sensors (FOPS) have been widely researched and implemented for structural health monitoring (SHM). FBG essentially provides localized strain information, while FOPS gives a global indication of the structural health of materials. An FBG written on the polarization maintaining (PM) fiber can thus be used for both global structural monitoring and local strain sensing. However each sensor has to be used with its own hardware and processing. For gratings written on PM fibers two Bragg reflections, corresponding to two modes of polarization, are observed. While both Bragg wavelengths shift under longitudinal strain in unison, their relative peak amplitude does not change. In this paper, a novel concept is proposed which makes the peak amplitudes responsive to the longitudinal strain. This relative amplitude of both the peaks is used for the first time to determine the state of polarization (SOP) with no additional optical systems. With this additional information on SOP, PM-FBGs can be used for both, local and global SHM simultaneously. Further, a new design has been proposed which gives improved information on the damaged location in beam structures. This can be further extended to other complex geometries.

  4. Microstructure-FBG hybrid load cell

    NASA Astrophysics Data System (ADS)

    Fiorin, Rodrigo; da Costa, Larissa N.; Abe, Ilda; de Oliveira, Valmir; Lohmann, Andre; Kalinowski, Hypolito J.

    2014-05-01

    We report the fabrication of an hybrid fibre optic and T-shaped microstructrure inscribed in soda lime microscope slides by using femtosecond laser irradiation technique. that allow to construct true 3-D structures. Within the T-shaped structure a FBG was inserted and glued with photopolymer adhesive. The hybrid structure is sensitive to hydrostatic pressure. Calibration load tests were performed in the range 0 - 100 N.

  5. Feeding the Probiotic Enterococcus faecium Strain NCIMB 10415 to Piglets Specifically Reduces the Number of Escherichia coli Pathotypes That Adhere to the Gut Mucosa

    PubMed Central

    Guenther, Sebastian; Oelgeschläger, Kathrin; Kinnemann, Bianca; Pieper, Robert; Hartmann, Susanne; Tedin, Karsten; Semmler, Torsten; Neumann, Konrad; Schierack, Peter; Bethe, Astrid; Wieler, Lothar H.

    2013-01-01

    Feed supplementation with the probiotic Enterococcus faecium for piglets has been found to reduce pathogenic gut microorganisms. Since Escherichia coli is among the most important pathogens in pig production, we performed comprehensive analyses to gain further insight into the influence of E. faecium NCIMB 10415 on porcine intestinal E. coli. A total of 1,436 E. coli strains were isolated from three intestinal habitats (mucosa, digesta, and feces) of probiotic-supplemented and nonsupplemented (control) piglets. E. coli bacteria were characterized via pulsed-field gel electrophoresis (PFGE) for clonal analysis. The high diversity of E. coli was reflected by 168 clones. Multilocus sequence typing (MLST) was used to determine the phylogenetic backgrounds, revealing 79 sequence types (STs). Pathotypes of E. coli were further defined using multiplex PCR for virulence-associated genes. While these analyses discerned only a few significant differences in the E. coli population between the feeding groups, analyses distinguishing clones that were uniquely isolated in either the probiotic group only, the control group only, or both groups (shared group) revealed clear effects at the habitat level. Interestingly, extraintestinal pathogenic E. coli (ExPEC)-typical clones adhering to the mucosa were significantly reduced in the probiotic group. Our data show a minor influence of E. faecium on the overall population of E. coli in healthy piglets. In contrast, this probiotic has a profound effect on mucosa-adherent E. coli. This finding further substantiates a specific effect of E. faecium strain NCIMB 10415 in piglets against pathogenic E. coli in the intestine. In addition, these data question the relevance of data based on sampling fecal E. coli only. PMID:24123741

  6. Development of fast FBG interrogator with wavelength-swept laser

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuya; Shinoda, Yukitaka

    2015-05-01

    The objective of this research is the construction of a structural health monitoring system that uses fiber Bragg grating (FBG) to determine the health of structures. We develop fast FBG interrogator for real-time measurement of the reflected wavelength of a multipoint FBG to monitor the broadband vibration of a structure. This FBG interrogator, which combines a wavelength-swept laser and a real-time measurement system is capable of measuring wavelength within a standard deviation of 2×10-3 nm or less. We have demonstrated that the FBG interrogator is able to measure vibration that has a resonance frequency of 440 Hz at intervals of 0.1 ms with a multipoint FBG.

  7. Ultrasonic Sensitivity of Strain-Insensitive Fiber Bragg Grating Sensors and Evaluation of Ultrasound-Induced Strain

    PubMed Central

    Tsuda, Hiroshi; Kumakura, Kenji; Ogihara, Shinji

    2010-01-01

    In conventional ultrasound detection in structures, a fiber Bragg grating (FBG) is glued on or embedded in the structure. However, application of strain to the structure can influence the sensitivity of the FBG toward ultrasound and can prevent its effective detection. An FBG can work as a strain-insensitive ultrasound sensor when it is not directly glued to the monitored structure, but is instead applied to a small thin plate to form a mobile sensor. Another possible configuration is to affix an FBG-inscribed optical fiber without the grating section attached to the monitored structure. In the present study, sensitivity to ultrasound propagated through an aluminum plate was compared for a strain-insensitive FBG sensor and an FBG sensor installed in a conventional manner. Strains induced by ultrasound from a piezoelectric transducer and by quasi-acoustic emission of a pencil lead break were also quantitatively evaluated from the response amplitude of the FBG sensor. Experimental results showed that the reduction in the signal-to-noise ratio for ultrasound detection with strain-insensitive FBG sensors, relative to traditionally-installed FBG sensors, was only 6 dB, and the ultrasound-induced strain varied within a range of sub-micron strains. PMID:22163523

  8. A novel multifunctional optical fiber sensor based on FBG and fiber optic coupler

    NASA Astrophysics Data System (ADS)

    Fu, Tao; Fan, Jiuming; Wang, Chang; Liu, Tongyu; Leng, Jinsong

    2008-03-01

    This paper introduces a novel multifunctional fiber sensor with two FBGs (measuring temperature and strain simultaneously) and a fiber optic coupler (monitoring the damage of composite) for structural health monitoring. Two FBGs with different wavelengths are abreast connected to an optical splitter: One is capsulated in glass capillary tube to measure temperature and not affected by strain, the other one is to measure temperature and strain. The other port of the former FBG is connected to the fiber optic coupler, using the transmission intensity in grating for structural health monitoring (SHM) of composite materials. It is pivotal to discriminate the variable of it caused by temperature and strain, as the wavelength of FBG varies with temperature and strain simultaneously. The technique is designed for distinguishing strain and temperature to solve the cross sensitivity problem in this paper. A series experiments demonstrate that the novel multifunctional optical fiber sensor possesses high sensitivity and high precision. With composite materials being used widely in aerospace engineering, national defence, civil engineering, oil field and etc, monitoring the damage of them is more important regarded. The temperature and strain affect the damage of composite materials mostly. Combined with the AE events, according to the temperature and strain of composite materials, the sensor can confirm whether they are demolished and how intensity they are damaged.

  9. 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.

  10. 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

    2015-01-01

    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

  11. 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

  12. Miniature fiber Bragg grating sensor interrogator (FBG-Transceiver) system for use in aerospace and automotive health monitoring systems

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    Fiber Bragg grating sensors (FBGs) have gained rapid acceptance in aerospace and automotive structural health monitoring applications for the measurement of strain, stress, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion distributed at multiple locations within the structure using a single fiber element. The most prominent advantages of FBGs are: small size and light weight, multiple FBG transducers on a single fiber, and immunity to radio frequency interference. A major disadvantage of FBG technology is that conventional state-of-the-art fiber Bragg grating interrogation systems are typically bulky and heavy bench top instruments that are assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the need for a compact FBG interrogation system, this paper describes recent progress towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-Transceiver TM) system based on multi-channel integrated optic sensor (InOSense) microchip technology. The hybrid InOSense microchip technology enables the integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogators systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm small form factor (SFF) package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation. The sponsor of this program is NAVAIR under a DOD SBIR contract.

  13. HtrA stress protein is involved in intramacrophagic replication of adherent and invasive Escherichia coli strain LF82 isolated from a patient with Crohn's disease.

    PubMed

    Bringer, Marie-Agnès; Barnich, Nicolas; Glasser, Anne-Lise; Bardot, Olivier; Darfeuille-Michaud, Arlette

    2005-02-01

    Adherent and invasive Escherichia coli (AIEC) bacteria isolated from Crohn's disease patients are able to greatly replicate within macrophages without escaping from the phagosome and without inducing macrophage death. In the present study, evidence is provided that in AIEC strain LF82 the htrA gene encoding the stress protein HtrA is essential for intracellular replication within J774-A1 macrophages. Deletion of the htrA gene in strain LF82 induced increased sensitivity of the isogenic mutant to oxidative stress caused by hydrogen peroxide and a reduced rate of growth in an acid and nutrient-poor medium partly reproducing the microenvironment of the phagosome. In vitro experiments using an LF82 htrA gene promoter fusion with the lacZ gene revealed a 38-fold activation of the promoter in AIEC LF82 intramacrophagic bacteria. The CpxRA two-component signaling pathway was not involved in this activation. In addition, the activation of the LF82 htrA gene promoter was not observed in the nonpathogenic E. coli K-12 intramacrophagic bacteria, indicating that the AIEC LF82 genetic background is crucial for induction of htrA gene transcription during phagocytosis. PMID:15664909

  14. [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. PMID:26117887

  15. An optimized FBG-based fatigue monitoring strategy on deepwater risers

    NASA Astrophysics Data System (ADS)

    Li, Xuan; Ren, Peng; Zhou, Zhi; Ou, Jinping

    2014-11-01

    For the sake of the increasing demands of oil and gas essential, scientists and engineers have exerted great efforts in obtaining natural resources deposited in the deep water. Risers, as the channel between platform and wellhead, play a key role in oil and gas transportation. Subjected to coarse environmental conditions and uncertain loading patterns, risers would display complex dynamic behaviors which could result in severe fatigue damages. Recently, riser response is commonly measured using passive and durable Fiber Bragg Grating (FBG) strain sensors for industry safety, especially for Integrity Management (IM). However, for technique difficulties as well as economical consideration, it is impossible to execute distributed fatigue monitoring on the whole riser, which makes it essential to find out an optimized method utilizing the least number of sensors and reconstruct the global response of risers. This paper propose a method which combines H2 norms and Kalman filter to give optimal state estimation of risers based on limited FBG-based dynamic strain information. The H2 norms are used to give guideline for optimized sensor placement. Meanwhile, Kalman filter realize the global response reconstruction of risers as well as minimize the environmental disturbance. The accuracy and efficiency of the method has been verified by a numerical case. This study provides an FBG-based early warning technique for industry application of deepwater risers in future.

  16. 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. PMID:23070491

  17. CARD15 variants determine a disturbed early response of monocytes to adherent-invasive Escherichia coli strain LF82 in Crohn's disease.

    PubMed

    Peeters, H; Bogaert, S; Laukens, D; Rottiers, P; De Keyser, Filip; Darfeuille-Michaud, A; Glasser, A-L; Elewaut, D; De Vos, M

    2007-06-01

    Caspase activation and recruitment domain 15 (CARD15) and Toll-like receptor 4 (TLR4) are respectively intracellular and membrane-bound receptors for bacterial cell wall components [respectively muramyl dipeptide (MDP) and lipopolysaccharide (LPS)]. Polymorphisms in CARD15 and TLR4 have been linked with Crohn's disease (CD). Adherent-invasive Escherichia coli (AIEC) strains with particular adhesion and invasion characteristics have been specifically associated with CD ileal mucosa. The aim of this study was to investigate the functional impact of these polymorphisms on monocytes in patients with CD, in response to MDP, LPS and AIEC strain LF82. Monocytes were isolated from 40 patients with CD using magnetic cell sorting, stimulated with LPS or MDP or infected with AIEC. IL-1beta, IL-6, IL-8, IL-10, IL-12 and tumour necrosis factor alpha induction was assessed using quantitative real time-polymerase chain reaction, Cytometric Bead Array and ELISA. Bacterial intracellular survival and replication was assessed using a gentamicin protection assay. Results were linked with the presence of CARD15 and TLR4 polymorphisms. Monocytes of patients with CARD15 polymorphisms showed an early reduced cytokine response (IL-1beta, IL-6 and IL-10) to infection with AIEC, which was restored after 20 h. A gene-dose effect was seen, comparing wild-types, heterozygotes and homozygotes. We found no differences in intracellular survival and replication of AIEC. Heterozygous carriage of TLR4 polymorphisms did not influence monocyte response. In conclusion, patients with CD carrying CARD15 polymorphisms show a disturbed early inflammatory monocyte response after infection with AIEC strain LF82. For the first time, a functional defect was detected in single heterozygous carriers. These findings reflect the potential role of a genetically altered host response to disease-related bacteria in the pathogenesis of CD. PMID:17504508

  18. 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

  19. 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

    2015-01-01

    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

  20. 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

  1. 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

    2015-01-01

    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

  2. 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).

  3. Development of a FBG probe for non-invasive carotid pulse waveform assessment

    NASA Astrophysics Data System (ADS)

    Leitão, C.; Bilro, L.; Alberto, N.; Antunes, P.; Lima, H.; André, P. S.; Nogueira, R.; Pinto, J. L.

    2012-06-01

    One of the early predictors of cardiovascular diseases, with growing interest, is the arterial stiffness which is typically evaluated through the velocity and morphology of the arterial pressure wave. In each cardiac cycle the heart generates a pressure wave which propagates through the arterial tree. Along its path, the pressure wave interacts with the arterial walls and, consequently, the morphology of a local arterial pressure wave can be assessed by the arterial distention movement. Due to its superficiality, proximity of the heart and high probability of atherosclerosis development, the carotid artery has particular interest to be monitored. In this work, the development of a non-invasive fibre Bragg grating (FBG) probe for the acquisition of the arterial distention wave is presented. Comparing to traditional methods, optical FBG based sensors can offer many advantages, namely, compactness, immunity to electromagnetic interference, high sensitivity, low noise and immunity to light source intensity due to its codification in the wavelength domain. The arterial movements induce strain on a uniform FBG, with the arterial distention pattern. The carotid pulse wave was successful accessed in young human carotid artery, with an acquisition rate of 950 Hz, allowing a clear distinction of the carotid pulse identification points.

  4. Fiber Bragg grating dynamic strain sensor using an adaptive reflective semiconductor optical amplifier source.

    PubMed

    Wei, Heming; Tao, Chuanyi; Zhu, Yinian; Krishnaswamy, Sridhar

    2016-04-01

    In this paper, a reflective semiconductor optical amplifier (RSOA) is configured to demodulate dynamic spectral shifts of a fiber Bragg grating (FBG) dynamic strain sensor. The FBG sensor and the RSOA source form an adaptive fiber cavity laser. As the reflective spectrum of the FBG sensor changes due to dynamic strains, the wavelength of the laser output shifts accordingly, which is subsequently converted into a corresponding phase shift and demodulated by an unbalanced Michelson interferometer. Due to the short transition time of the RSOA, the RSOA-FBG cavity can respond to dynamic strains at high frequencies extending to megahertz. A demodulator using a PID controller is used to compensate for low-frequency drifts induced by temperature and large quasi-static strains. As the sensitivity of the demodulator is a function of the optical path difference and the FBG spectral width, optimal parameters to obtain high sensitivity are presented. Multiplexing to demodulate multiple FBG sensors is also discussed. PMID:27139682

  5. Validation of long-term measurements from FBG sensors

    NASA Astrophysics Data System (ADS)

    Abdel-Jaber, Hiba; Glisic, Branko

    2016-04-01

    Temperature monitoring has been of increased importance in recent years due to the need for temperature measurements in order to compensate other measurement parameters, such as strain, and the increased attention to understanding thermal behaviors of structures in order to assess their performance and condition. To ensure the accuracy of thermal compensation and study of thermal behavior, reliable long-term temperature measurements are required. In this paper, two methods that are aimed at validating long-term temperature measurements are created and their application is presented. The methods differ in the type of data they use for the purpose of validation. The first method relies on the existence of two independent temperature sensors at the same location. Validation is performed by comparing the measurements from the two sensors to one another, and discrepancies between the two data sets indicate malfunction or drift in at least one of the sensors. The second method is applicable to the more general case where only one temperature sensor is available at a given location. The method thus utilizes ambient temperature data from a nearby weather tower to validate measurements from the sensor. The two methods are applied to temperature measurements from FBG sensors installed on Streicker Bridge on the Princeton University campus. The methods successfully identified and characterized malfunction and drift in some of the sensors and confirmed stable measurements in other sensors.

  6. Escherichia coli O157:H7 Strains That Persist in Feedlot Cattle Are Genetically Related and Demonstrate an Enhanced Ability To Adhere to Intestinal Epithelial Cells ▿

    PubMed Central

    Carlson, Brandon A.; Nightingale, Kendra K.; Mason, Gary L.; Ruby, John R.; Choat, W. Travis; Loneragan, Guy H.; Smith, Gary C.; Sofos, John N.; Belk, Keith E.

    2009-01-01

    A longitudinal study was conducted to investigate the nature of Escherichia coli O157:H7 colonization of feedlot cattle over the final 100 to 110 days of finishing. Rectal fecal grab samples were collected from an initial sample population of 788 steers every 20 to 22 days and microbiologically analyzed to detect E. coli O157:H7. The identities of presumptive colonies were confirmed using a multiplex PCR assay that screened for gene fragments unique to E. coli O157:H7 (rfbE and fliCh7) and other key virulence genes (eae, stx1, and stx2). Animals were classified as having persistent shedding (PS), transient shedding (TS), or nonshedding (NS) status if they consecutively shed the same E. coli O157:H7 genotype (based on the multiplex PCR profile), exhibited variable E. coli O157 shedding, or never shed morphologically typical E. coli O157, respectively. Overall, 1.0% and 1.4% of steers were classified as PS and NS animals, respectively. Characterization of 132 E. coli O157:H7 isolates from PS and TS animals by pulsed-field gel electrophoresis (PFGE) typing yielded 32 unique PFGE types. One predominant PFGE type accounted for 53% of all isolates characterized and persisted in cattle throughout the study. Isolates belonging to this predominant and persistent PFGE type demonstrated an enhanced (P < 0.0001) ability to adhere to Caco-2 human intestinal epithelial cells compared to isolates belonging to less common PFGE types but exhibited equal virulence expression. Interestingly, the attachment efficacy decreased as the genetic divergence from the predominant and persistent subtype increased. Our data support the hypothesis that certain E. coli O157:H7 strains persist in feedlot cattle, which may be partially explained by an enhanced ability to colonize the intestinal epithelium. PMID:19617387

  7. 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.

  8. High performance FBG interrogation technology with scan fiber laser

    NASA Astrophysics Data System (ADS)

    Yang, Yuanhong; Ma, Youchun; Yang, Minwei

    2010-11-01

    A Fiber Bragg gratings (FBG) Interrogation scheme with scan fiber laser was demonstrated. The ring cavity scan fiber laser was investigated and the scan fiber laser module was made and test, the 200Hz scan frequency, ~0.02nm line width, more than 40nm scan range and more than 1 mW output power were obtained. A 12 channels, 20 FBGs per channel FBG interrogator was made with this laser module and the high speed signal process circuit base on FPGA. The centroid finding method which has advantage on interrogation speed and accurate was taken for finding the peak of the return FBG spectrum. The FBG interrogator was test and less than 3pm standard deviation with 200Hz scan frequency were obtained.

  9. Fiber laser FBG sensor system by using a spectrometer demodulation

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjin; Song, Minho

    2011-05-01

    We suggest a spectrometer demodulation method of FBG sensors for the possible uses in wind power generator's blade monitoring. High signal-to-noise ratio outputs and linear demodulation were obtained by combining a fiber laser light source and a spectrometer which used a holographic volume grating and a 512-pixel PD array. Preliminary experimental results are presented to show the feasibility of the suggested FBG demodulation system.

  10. 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.

  11. 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

  12. FBG sensor system based on wavelength-swept active mode-locking laser with RSOA gain medium

    NASA Astrophysics Data System (ADS)

    Kim, Hyo-jin; Lee, Hwi Don; Jeong, Myong Yung; Kim, Chang-Seok; Lee, Ju Han

    2011-05-01

    We performed an experiment of wavelength-swept laser based on active mode-locking on reflective semiconductor optical amplifier (RSOA). Since this laser does not have a wavelength-selecting filter, it can achieve a high sweeping speed and reduce the component cost and size. Compared to the conventional SOA gain medium, RSOA shows a merit of higher efficiency of cross gain modulation due to the twice propagation of active gain region. We applied this laser to Fiber Bragg grating (FBG) strain sensor system which can have faster data acquisition speed than conventional wavelength-swept laser method. The linear response of FBG peak for the applied strain is monitored using the proposed laser source.

  13. 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

    2014-01-01

    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

  14. 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. PMID:24351757

  15. Structural health monitoring of CFRP airframe structures using fiber-optic-based strain mapping

    NASA Astrophysics Data System (ADS)

    Takahashi, I.; Sekine, K.; Kume, M.; Takeya, H.; Iwahori, Y.; Minakuchi, S.; Takeda, N.; Enomoto, K.

    2012-04-01

    This paper proposes structural health monitoring technology based on the strain mapping of composite airframe structures through their life cycles by FBG sensors. We carried out operational load tests of small-sized mockup specimens of CFRP pressure bulkhead and measured the strain by FBG sensors. In addition, we confirmed strain change due to stiffener debondings. Moreover, debonding detectability of FBG sensors were investigated through the strain monitoring test of CFRP skin-stiffener panel specimens. As a result, the strain distribution varied with damage configurations. Moreover, the change in strain distribution measured by FBG sensors agrees well with numerical simulation. These results demonstrate that FBG sensors can detect stiffener debondings with the dimension of 5mm in composite airframe structures.

  16. High-speed system for FBG-based measurements of vibration and sound

    NASA Astrophysics Data System (ADS)

    Karabacak, Devrez M.; Ibrahim, Selwan K.; Koumans, Yorick; Meulblok, Bastiaan; Knoppers, Rik

    2016-05-01

    Fiber Bragg Gratings (FBGs) allow for optical detection of localized physical effects without the need to couple the light out and back into a fiber, enabling robust and multiplexed sensor systems. The need of combining wide bandwidth and high resolution for dynamic sensing applications, like acoustics and vibrations, has presented significant challenges for FBG-based solutions. Here, we present a novel FBG-based measurement system enabled by using high-speed and highprecision tunable laser-based optical interrogation scheme. Multiple levels of integrated wavelength referencing coupled with low-noise high-speed electronics allow for spectral feature tracking at a resolution of <20 fm at kHz-frequencies. In combination with fiber accelerometers that employ unique force transmission mechanisms, amplifying strain on the Bragg grating and increasing the resonance frequency of the transducer, resolutions <10 μg (150 Hz bandwidth) to submg resolution in kHz-frequencies is achieved. Similarly, compact wavelength-multiplexed hydrophones with wide range linearity and dynamic range, sub-Pa resolution and flat-sensitivity down to static pressures are demonstrated. The sensors are demonstrated to be customizable to application-specific requirements, and designed to be scalable to large quantity reproducible manufacturing. In contrast to interferometry-based solutions, the tunable swept-laser detection scheme in combination with strain-based FBG sensors provides a cost-effective system that allows for easy scaling of sensor counts per fiber with multiple fibers being simultaneously recorded. Finally, the integrated high accuracy triggering and hybrid measurement capabilities present the potential to monitor sounds and vibrations in a wide range of applications from seismic surveys to machine and structural monitoring applications in harsh environments.

  17. HIV Medication Adherence

    MedlinePlus

    HIV Treatment HIV Medication Adherence (Last updated 3/1/2016; last reviewed 3/1/2016) Key Points Medication adherence means sticking ... exactly as prescribed. Why is adherence to an HIV regimen important? Adherence to an HIV regimen gives ...

  18. Evaluation of Crack Suppression Effect of TiNi SMA Foil Embedded in CFRP Cross-Ply Laminates with Embedded Small-Diameter FBG Sensor

    NASA Astrophysics Data System (ADS)

    Amano, Masataro; Okabe, Yoji; Takeda, Nobuo

    A Ti-Ni shape memory alloy (SMA) foil and a small-diameter fiber Bragg grating (FBG) sensor were embedded simultaneously into a CFRP cross-ply laminate. When the specimen was heated, the recovery compressive force was generated from the embedded SMA foil, which homogenized the non-uniform strain distribution caused by cracks in the 90° ply. Then, the tensile stress in the 90° ply was relaxed and the occurrence of new transverse cracks was suppressed. This effect was evaluated with the embedded FBG sensor. When the specimen was heated, the deformed reflection spectrum of the FBG returned to its original shape, which suggested that Ti-Ni SMA foil was effective to suppress the damage. However, relaxation of thermal residual tensile stress in the 90° ply was also effective. The result of the 3D FEA suggested that the suppression of damage occurrence and growth was mainly caused by the relaxation of thermal residual tensile stress.

  19. 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

    2014-01-01

    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. PMID:25375335

  20. FBG interrogation method based on wavelength-swept laser

    NASA Astrophysics Data System (ADS)

    Qin, Chuan; Zhao, Jianlin; Jiang, Biqiang; Rauf, Abdul; Wang, Donghui; Yang, Dexing

    2013-06-01

    Wavelength-swept laser technique is an active demodulation method which integrates laser source and detecting circuit together to achieve compact size. The method also has the advantages such as large demodulation range, high accuracy, and comparatively high speed. In this paper, we present a FBG interrogation method based on wavelength-swept Laser, in which an erbium-doped fiber is used as gain medium and connected by a WDM to form a ring cavity, a fiber FP tunable filter is inserted in the loop for choosing the laser frequency and a gas absorption cell is adopted as a frequency reference. The laser wavelength is swept by driving the FP filter. If the laser wavelength matches with that of FBG sensors, there will be some strong reflection peak signals. Detecting such signals with the transmittance signal after the gas absorption cell synchronously and analyzing them, the center wavelengths of the FBG sensors are calculated out at last. Here, we discuss the data processing method based on the frequency reference, and experimentally study the swept laser characteristics. Finally, we adopt this interrogator to demodulate FBG stress sensors. The results show that, the demodulation range almost covers C+L band, the resolution and accuracy can reach about 1pm or less and 5pm respectively. So it is very suitable for most FBG measurements.

  1. 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.

  2. Design, integration, and testing of a compact FBG interrogator, based on an AWG spectrometer

    NASA Astrophysics Data System (ADS)

    Trita, Andrea; Vickers, Garrie; Mayordomo, Iker; van Thourhout, Dries; Vermeiren, Jan

    2014-05-01

    Fiber Bragg Grating or FBG sensors are gaining more and more interest in structural health monitoring of composite materials. Often, the weakest point in such a system is the ingress point of the fiber sensing chain into the composite material. For this reason we have developed a strongly miniaturized FBG interrogator unit with wireless power and data transmission, which can be incorporated in the composite structure. The interrogator is based on an arrayed waveguide grating (AWG) filter fabricated in a SOI technology, which is tailored in such a way to give large cross-talk between neighboring channels. The AWG signals are read by a linear 128 pixel InGaAs array flip-chipped on top of the Photonic Circuit (PIC). The spectrometer unit is completed with a ROIC mounted on the same substrate. The SLED and remaining electronics are integrated on a small and thin substrate and surrounded by the wireless antenna. The interrogator has an overall dimension of 100 mm diameter by max 7 mm height. The power dissipation of the electronics unit is limited to 1.5 W. The unit is capable of measuring strain values as low as 5 micro-strain.

  3. Fiber Bragg grating strain sensor for hard rocks

    NASA Astrophysics Data System (ADS)

    Castro-Caicedo, Alvaro; Nieto-Callejas, María. J.; Torres, Pedro

    2015-09-01

    Strain is an important property to be measured in rock structures such as tunnels, slopes, dams, and mining. However, commercial surface mountable fiber Bragg grating (FBG) strain sensors are packaged in planar configuration, which is not appropriate for the irregular surface of the rocks since an unacceptable bonding layer fails to transfer the strain from the rock to the FBG. As a first approach to this problem, in this work we analyze packaged FBG sensors for cylindrical samples of hard rocks. A calibration process was carried out to evaluate the performance of the packaging and bonding layer as compared to electrical resistance strain gage methods. We show the importance of both packaging and bonding layer in FBG sensor technology for measuring strain in hard rocks.

  4. 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).

  5. FBG sensors for painted wood panel deformation monitoring

    NASA Astrophysics Data System (ADS)

    Falciai, Riccardo; Trono, Cosimo; Lanterna, Giancarlo; Castelli, Ciro

    2003-07-01

    The wood support is an essential element of the works of art and is highly sensitive to the environmental climate modification. Wood deformations may have irreversible destructive effects on the work of ar t. The use of fiber Bragg grating (FBG) sensors for the quasi-distributed in-situ measurement and continuous monitoring of the painted wood panel deformations is proposed. FBG sensors have high resolution low invasivity and intrinsic safety. The results of a set of measurement on a wood panel in different climate conditions are presented. The applicability of fiber Bragg grating sensors to the cultural heritage is demonstrated.

  6. Deformation monitoring of wooden works of art using FBG sensors

    NASA Astrophysics Data System (ADS)

    Falciai, Riccardo; Trono, Cosimo; Lanterna, Giancarlo; Castelli, Ciro

    2004-09-01

    Wood support is an essential element of the works of art and is highly sensitive to the environmental climate modification. Wood deformations may have irreversible destructive effects on the work of art. The use of fiber Bragg grating (FBG) sensors for the quasi-distributed in-situ measurement and continuous monitoring of the painted wood panel deformations is proposed. FBG sensors have high resolution low invasivity and intrinsic safety. The effects of relative humidity changes were measured on a wood panel, by monitoring the deformations in the wood structure using an array of fiber Bragg gratings glued to different critical points.

  7. FBG sensor for physiologic monitoring in M-health application

    NASA Astrophysics Data System (ADS)

    Lee, Chi Chung; Hung, Kevin; Chan, Wai-Man; Wu, Y. K.; Choy, Sheung-On; Kwok, Paul

    2011-12-01

    In this paper, a wearable physiologic monitoring system using FBG sensors is investigated. The FBG sensors with the capability of sensing temperature, movement, and respiration are connected to the wireless transceiver, microcontroller and server for wireless and long distance physiologic monitoring and analysis. Biosignals recorded experimentally are analyzed and compared with the data obtained in the traditional medical data acquisition system. The system investigated in this paper can be used in an m-health shirt, which has the capability to measure and wirelessly transmit electrocardiogram, respiration, movement, and body temperature signal to a remote station, with other plug-in modules.

  8. 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

  9. Analysis of the performance of temperature compensation for fiber Bragg grating strain sensor

    NASA Astrophysics Data System (ADS)

    Meng, Fanyong; Jia, Limin

    2015-07-01

    FBG(fiber Bragg grating) strain sensor are widely applied in structure health monitoring, the temperature compensation problem is a key issue that impact the performance of the strain sensor, many kinds of temperature compensation method also have been put forward, but the compensation result get from these method can't meet the engineering requirements very well, especially when the ambient temperature changes rapidly due to the sunshine, the wind, the rain or other factors, and these impact can't avoid when monitoring an open-air structure project. Through engineering case and experiments test found that, the inaccurate compensation temperature is the key reason lead to test result error, and closer analysis could found that the temperature from strain sensitive FBG and temperature sensitive FBG have non synchronous phenomenon, and the error could be reach 1 degrees Celsius, so use the temperature from the same moment to compensate the strain calculation also can't get accurate results. The author thinks that the temperature non synchronous phenomenon may be caused by the temperature sensitive FBG and strain sensitive FBG have different package structure or package material, also may be installed on different positions, because all of these factors may lead to inconsistent temperature response speed between the two FBG when the ambient temperature changed rapidly. In order to confirm this conclusion, designed a FBG strain sensor package structure, the temperature sensitive FBG and strain sensitive FBG are packaged in one and the same structure with special stress isolation mechanism. Through temperature chamber test and engineering simulation experiment verified that the compensation temperature error could be reduced to 0.1 degrees Celsius, this will greatly improve the accuracy of temperature compensation for the FBG strain sensor.

  10. Adaptive two-wave mixing wavelength demodulation of fiber Bragg grating sensor for monitoring dynamic strains

    NASA Astrophysics Data System (ADS)

    Qiao, Yi; Zhou, Yi; Krishnaswamy, Sridhar

    2005-05-01

    A two-wave mixing (TWM) wavelength demodulator using InP:Fe photorefractive crystal (PRC) in the C-band (1530-1570nm) is demonstrated. The system can be used as a wavelength demodulator for use with Fiber Bragg Grating (FBG) sensors to monitor dynamic strains. In this configuration, the FBG is illuminated with a broadband source, and any strain in the FBG is encoded as a wavelength shift of the light reflected by the FBG. The reflected light from the FBG is spilt into two unbalanced paths and both beams (pump and signal) mix in the PRC. Any wavelength shift of the reflected light results in an equivalent phase shift between the pump and signal beams as they travel unbalanced path lengths. Since TWM is an adaptive process, the two interfering beams are naturally in quadrature and remain in quadrature even in the presence of large quasi-static strains. We demonstrate that FBG demodulation using TWM has the ability to selectively monitor dynamic strains without the need for active compensation of large quasi-static strains that otherwise would cause the FBG sensor to drift. As TWM interferometers can be readily multiplexed at relatively low cost; the proposed technique can be used to demodulate signals from a network of FBG sensors for use in structural health monitoring.

  11. Development of a FBG vortex flow sensor for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Cheng, L. K.; Schiferli, W.; Nieuwland, R. A.; Franzen, A.; den Boer, J. J.; Jansen, T. H.

    2011-05-01

    A robust fibre optic flow sensor has been developed to measure liquid or gas flows at ambient temperatures up to 300 ºC and pressures up to 100 bar. While such environmental conditions are typical in pressurized steam systems in the oil and gas industry (downhole and surface), wider applications are envisaged. The flow sensor uses a specially-designed bluff body to generate vortex-induced pressure fluctuations as a function of flow. The pressure fluctuations result in mechanical strain fluctuations in the sensor plate which is attached to the bluff-body. This is detected by means of a Fibre Bragg Grating (FBG). The frequency of the pressure fluctuations is proportional to the flow velocity and is measured by analyzing the spectrum of the FBG sensor signal. Flow velocity measurements ranging from ~1 m/s to ~25 m/s have been demonstrated. Special mechanical design, gluing and packaging processes have been developed to enable applications at high temperatures and high pressures (HPHT). Although the working principle is the same as for conventional vortex flow meters, this flow sensor does not require electronics, which is a great advantage at high temperatures.

  12. Polarization multiplexed interrogation technique for FBG sensor array

    NASA Astrophysics Data System (ADS)

    Sikdar, Debabrata; Tiwari, Vinita; Soni, Anupam; Jaiswal, Ritesh; Bhanot, Surekha

    2015-09-01

    This paper proposes a polarization multiplexed interrogation technique for fiber Bragg grating (FBG) sensor array. The novelty of the proposed model is its ability to reduce interference and cross talk, thus allowing larger number of FBG sensors to be interrogated in an array. The calibration technique has been illustrated in this work for the FBG sensor array, where data from each sensor are linearly polarized and multiplexed before co-propagation, to find out the tapping points that enable identification of each sensor data uniquely. Simulation has been carried out for odd number and even number of sensors in an array. Even with interfering input, this proposed scheme can interrogate and distinctively identify each sensor data using appropriate tuning of polarization-splitter, polarization-rotator, and polarization-attenuator at the detector end during the calibration process. The significance of the proposed method is its compact size, which makes this calibration system ready to be deployed in real-time sensing applications and data acquisition from the FBG sensor array.

  13. Evidence that extracellular components function in adherence of Actinobacillus actinomycetemcomitans to epithelial cells.

    PubMed Central

    Meyer, D H; Fives-Taylor, P M

    1993-01-01

    Extracellular microvesicles and a highly proteinaceous polymer associated with a leukotoxin-producing strain, Actinobacillus actinomycetemcomitans SUNY 75, were shown to increase adherence of other weakly adherent A. actinomycetemcomitans strains to KB epithelial cells. Images PMID:8406899

  14. 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.

  15. Structural health monitoring of an asymmetrical SMA reinforced composite using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Ho, Mei-po; Lau, Kin-tak; Au, Ho-yin; Dong, Yu; Tam, Hwa-yaw

    2013-12-01

    Embedded actuator and sensor technology provides accurate structural health monitoring and proper structural response of a structure in any harsh servicing situation. This paper describes the fabrication of a smart composite by embedding shape memory alloy (SMA) wires and fibre Bragg grating (FBG) sensors into a glass fabric reinforced polymeric composite. Mechanical performances of the composite under martensitic and austenitic stages of the SMA wires were studied, and its natural frequencies were also measured accordingly. The result shows that the shift of the natural frequency arises from temperature change, thus changing the mechanical properties of the SMA wires. The changes of strain, stress, curvature, and damping ratio were predicted from an asymmetrical lamination model. It was found that this model demonstrates certain attractive effects, including mechanical properties, the change of shape, and the natural frequency upon activation of the SMA wires.

  16. The oxidoreductase DsbA plays a key role in the ability of the Crohn's disease-associated adherent-invasive Escherichia coli strain LF82 to resist macrophage killing.

    PubMed

    Bringer, Marie-Agnès; Rolhion, Nathalie; Glasser, Anne-Lise; Darfeuille-Michaud, Arlette

    2007-07-01

    Adherent-invasive Escherichia coli (AIEC) isolated from Crohn's disease patients is able to adhere to and invade intestinal epithelial cells and to replicate in mature phagolysosomes within macrophages. Here, we show that the dsbA gene, encoding a periplasmic oxidoreductase, was required for AIEC strain LF82 to adhere to intestinal epithelial cells and to survive within macrophages. The LF82-DeltadsbA mutant did not express flagella and, probably as a consequence of this, did not express type 1 pili. The role of DsbA in adhesion is restricted to the loss of flagella and type 1 pili, as forced contact between bacteria and cells and induced expression of type 1 pili restored the wild-type phenotype. In contrast, the dsbA gene is essential for AIEC LF82 bacteria to survive within macrophages, irrespective of the loss of flagella and type 1 pilus expression, and the survival ability of LF82-DeltadsbA was as low as that of the nonpathogenic E. coli K-12, which was efficiently killed by macrophages. We also provide evidence that the dsbA gene is needed for LF82 bacteria to grow and survive in an acidic and nutrient-poor medium that partly mimics the harsh environment of the phagocytic vacuole. In addition, under such stress conditions dsbA transcription is highly up-regulated. Finally, the CpxRA signaling pathway does not play a role in regulation of dsbA expression in AIEC LF82 bacteria under conditions similar to those of mature phagolysosomes. PMID:17449627

  17. Persistent and transient Listeria monocytogenes strains from retail deli environments vary in their ability to adhere and form biofilms and rarely have inlA premature stop codons.

    PubMed

    Wang, Jingjin; Ray, Andrea J; Hammons, Susan R; Oliver, Haley F

    2015-02-01

    Based on recent risk assessments, up to 83% of listeriosis cases from deli meat in the United States are predicted to be from ready-to-eat deli meats contaminated during processing at retail grocery stores. Listeria monocytogenes is known to use sanitizer tolerance and biofilm formation to survive, but interplay of these mechanisms along with virulence potential and persistence mechanisms specific to deli environments had yet to be elucidated. In this study, 442 isolates from food and nonfood contact surfaces in 30 retail delis over 9 months were tested for inlA premature stop codons (PMSCs); inlA encodes InlA, which is necessary to cause listeriosis. A total of 96 isolates, composed of 23 persistent and 73 transient strains, were tested for adhesion and biofilm-forming ability and sanitizer tolerance. Only 10/442 isolates had inlA PMSCs (p<0.001). Strains with PMSCs were not persistent, even in delis with other persistent strains. Most (7/10) PMSC-containing isolates were collected from food contact surfaces (p<0.001); 6/10 PMSC-containing isolates were found in moderate prevalence delis (p<0.05). Persistent strains had enhanced adhesion on day 1 of a 5-day adhesion-biofilm formation assay. However, there was no significant difference in sanitizer tolerance between persistent and transient strains. Results suggest that foods contaminated with persistent L. monocytogenes strains from the retail environment are (1) likely to have wild-type virulence potential and (2) may persist due to increased adhesion and biofilm formation capacity rather than sanitizer tolerance, thus posing a significant public health risk. PMID:25569840

  18. 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.

  19. Pipeline monitoring using an integrated MFC/FBG system

    NASA Astrophysics Data System (ADS)

    Lee, Hyeonseok; Sohn, Hoon; Park, Hyun Woo

    2011-04-01

    This study proposes a new hybrid macro fiber composite/fiber Bragg grating (MFC/FBG) system that can excite and measure guided waves for pipeline monitoring using a single laser source and optical cables removing the need for conventional wire cables. Among various ultrasonic transducers, piezoelectric transducers and FBG sensors have been widely used because of their light weight, non-intrusive nature and compactness. Particularly for pipeline monitoring, a MFC transducer among other piezoelectric transducers is used because of its flexibility and conformability to a curved surface. In addition, conventional electric cables needed for power and data transmission are all replaced by optical cables, alleviating problems such as electromagnetic interference, signal attenuation and vulnerability to noise. A tunable laser is used as a common power source for guided wave generation and sensing. One of two laser beams split from the tunable laser, is used to actuate MFC transducers, and the other beam is used with FBG sensors to measure generated guided waves. The measured signals are processed to identify the existence of defects in pipeline structures such as wall thinning and longitudinal cracks. The feasibility of the proposed hybrid measurement system has been experimentally verified in a laboratory setup.

  20. Identification of impact damage in sandwich structures by application of high speed MEMS-OSA to FBG sensors

    NASA Astrophysics Data System (ADS)

    Okabe, Y.; Minakuchi, S.; Takeda, N.

    2005-05-01

    In this research, the authors developed various detection techniques for particular damages, such as debonding and impact damage, in sandwich panels consisting of composite face-sheets and aluminum honeycomb core with small-diameter optical fiber sensors. First, two methods for debonding detection were established taking advantage of the behavior of fillets formed on the adhesive layer between the core and the skin. One method uses the fracture of optical fibers, and the other one uses the shape recovery of the reflection spectrum from a fiber Bragg grating (FBG) sensor because of the release of thermal residual stress in the fillets. Secondly, as for impact damages, chirped FBG sensors were applied to monitor the change in strain distribution of the face-sheet due to the dent caused by the impact loadings. Furthermore, a newly developed MEMS-optical spectrum analyzer (MEMS-OSA) was introduced to identification of impact points and damages. This system could measure the reflection spectrum at very high speed. The change in the form of the reflection spectrum during the impact loading was found to be different depending on the impact energy and the impact location, and this tendency was confirmed by theoretical simulations using the change in the strain distribution obtained by foil strain gauges. These results show that the high speed measurement of the reflection spectrum by MEMS-OSA has a potential to identify the impact location and damage magnitude through the comparison with theoretical simulations.

  1. 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

  2. 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

    2015-01-01

    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

  3. The Crohn's disease-associated adherent-invasive Escherichia coli strain LF82 replicates in mature phagolysosomes within J774 macrophages.

    PubMed

    Bringer, Marie-Agnès; Glasser, Anne-Lise; Tung, Ching-Hsuan; Méresse, Stéphane; Darfeuille-Michaud, Arlette

    2006-03-01

    Adherent-invasive Escherichia coli (AIEC) bacteria isolated from Crohn's disease patients are able to extensively replicate within macrophages in large vacuoles. The mechanism by which AIEC bacteria survive within phagocytic cells is unknown. This report describes the maturation of AIEC LF82-containing phagosomes within J774 macrophages. LF82-containing phagosomes traffic through the endocytic pathway as shown by the sequential acquisition and loss of EEA1 and Rab7 and by accumulation of Lamp-1, Lamp-2 and cathepsin D. We demonstrated that AIEC LF82-containing phagosomes mature into active phagolysosomes where bacteria are exposed to low pH and to the degradative activity of cathepsin D. Finally, we showed that an acidic environment is necessary for replication of AIEC LF82 bacteria within J774 macrophages. Thus, evidence is provided that AIEC LF82 bacteria do not escape from the endocytic pathway but undergo normal interaction with host endomembrane organelles and replicate within acidic and cathepsin D-positive vacuolar phagolysosomes. PMID:16469058

  4. Biofilm-forming ability and adherence to poly-(methyl-methacrylate) acrylic resin materials of oral Candida albicans strains isolated from HIV positive subjects

    PubMed Central

    Uzunoglu, Emel; Dolapci, Istar; Dogan, Arife

    2014-01-01

    PURPOSE This study evaluated the adhesion to acrylic resin specimens and biofilm formation capability of Candida albicans strains isolated from HIV positive subjects' oral rinse solutions. MATERIALS AND METHODS The material tested was a heat-cured acrylic resin (Acron Duo). Using the adhesion and crystal violet assays, 14 oral Candida albicans isolated from HIV-positive subjects and 2 references Candida strains (C. albicans ATCC 90028 and C. albicans ATCC 90128) were compared for their biofilm production and adhesion properties to acrylic surfaces in vitro. RESULTS There were no significant differences in adhesion (P=.52) and biofilm formation assays (P=.42) by statistical analysis with Mann-Whitney test. CONCLUSION Denture stomatitis and increased prevalence of candidal carriage in HIV infected patients is unlikely to be related to the biofilm formation and adhesion abilities of C. albicans to acrylic resin materials. PMID:24605203

  5. Measurements of temperature during fatigue of a thermoplastic polymer composite using FBG sensors

    NASA Astrophysics Data System (ADS)

    Facchini, M.; Botsis, J.; Sorensen, L.

    2007-04-01

    It is well known that cyclic fatigue induces hysteretic heating and temperature increase in polymer composite materials. Optical sensing technology is well developed to perform efficient in-field monitoring of the thermo-mechanical behaviour of engineering composite structures in sectors ranging from automotive to aerospace, where the implications of thermal fatigue are important. In this paper an experimental method and its results for temperature measurements in a glass/polypropylene composite beam subjected to cyclic bending at 6 Hz are reported. Since the sensors are sensitive to both temperature and strain, they are placed on the surface and in the centre of the specimen during processing, thus minimizing the effects of the mechanical strain during loading. Temperature increases of 9 °C both inside and on the specimen surface are recorded with fibre Bragg grating (FBG) sensors and verified by full-field temperature analysis using infrared thermography on the surface and thermocouples on both the surface and through the thickness of the composite. Discrimination between relatively large dynamic strain (responsible for ~280 pm Bragg wavelength shift oscillations), birefringence (responsible for ~70 pm), and temperature variations (9 °C leads to a Bragg wavelength shift of ~240 pm) is achieved by suitable integration of embedded FBGs and optical data processing. The achieved temperature resolution is 1 °C. The method outlined in this paper can be applied in various experimental configurations for temperature measurements in polymeric materials.

  6. Adherence of Clostridium thermocellum to cellulose.

    PubMed Central

    Bayer, E A; Kenig, R; Lamed, R

    1983-01-01

    The adherence of Clostridium thermocellum, a cellulolytic, thermophilic anaerobe, to its insoluble substrate (cellulose) was studied. The adherence phenomenon was determined to be selective for cellulose. The observed adherence was not significantly affected by various parameters, including salts, pH, temperature, detergents, or soluble sugars. A spontaneous adherence-defective mutant strain (AD2) was isolated from the wild-type strain YS. Antibodies were prepared against the bacterial cell surface and rendered specific to the cellulose-binding factor (CBF) by adsorption to mutant AD2 cells. By using these CBF-specific antibodies, crossed immunoelectrophoresis of cell extracts revealed a single discrete precipitation peak in the parent strain which was absent in the mutant. This difference was accompanied by an alteration in the polypeptide profile whereby sonicates of strain YS contained a 210,000-molecular-weight band which was missing in strain AD2. The CBF antigen could be removed from cell extracts by adsorption to cellulose. A combined gel-overlay--immunoelectrophoretic technique demonstrated that the cellulose-binding properties of the CBF were accompanied by carboxymethylcellulase activity. During the exponential phase of growth, a large part of the CBF antigen and related carboxymethylcellulase activity was associated with the cells of wild-type strain YS. However, the amounts decreased in stationary-phase cells. Cellobiose-grown mutant AD2 cells lacked the cell-associated CBF, but the latter was detected in the extracellular fluid. Increased levels of CBF were observed when cells were grown on cellulose. In addition, mutant AD2 regained cell-associated CBF together with the property of cellulose adherence. The presence of the CBF antigen and related adherence characteristics appeared to be a phenomenon common to other naturally occurring strains of this species. Images PMID:6630152

  7. Sensitivity Enhancement of Strain Sensing Utilizing a Differential Pair of Fiber Bragg Gratings

    PubMed Central

    Zhang, Zhiyong; Yan, Lianshan; Pan, Wei; Luo, Bin; Wang, Ping; Guo, Likang; Zhou, Wei

    2012-01-01

    In strain measurement applications, the matched fiber Bragg gratings (FBG) method is generally used to reduce temperature dependence effects. The FBG parameters have to be designed to meet the requirements by the particular application. The bandwidth and slope of the FBG has to be balanced well, according to the measurement range, accuracy and sensitivity. A sensitivity enhanced strain demodulation method without sacrificing the measurement range for FBG sensing systems is proposed and demonstrated utilizing a pair of reference FBGs. One of the reference FBGs and the sensing FBG have almost the same Bragg wavelength, while the other reference FBGs has a Bragg wavelength offset relative to the sensing FBG. Reflected optical signals from the sensing FBG pass through two reference FBGs, and subtract from each other after the detection. Doubled strain measurement sensitivity is obtained by static rail load experiments compared to the general matched grating approach, and further verified in dynamic load experiments. Experimental results indicate that such a method could be used for real-time rail strain monitoring applications. PMID:22666008

  8. Oscillatory behaviour in Type IA FBG: ruling out chemical complexity

    NASA Astrophysics Data System (ADS)

    Simpson, George; Kalli, Kyriacos; Canning, John; Lacraz, Amedee

    2015-09-01

    Type IA FBG are regenerated gratings that appear in hydrogenated germanosilicate fibre of all types during prolonged UV exposure. The gratings are characterised by a large Bragg wavelength shift and a concomitant increase in the mean fibre core index. Modulated index changes are complex by comparison and significantly weaker, often characterised by oscillatory growth behaviour. Low thermal stability of Type IA gratings suggests a possible chemical role similar to thermally processed optical fibres where autocatalysis has been observed. We show that GeOH and SiOH formation are not out-of-phase and follow each other, with no evidence of autocatalysis, ruling out a chemical origin.

  9. 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.

  10. Fiber laser strain sensor based in the measurement of a Sagnac interferometer optical power spectrum

    NASA Astrophysics Data System (ADS)

    Durán Sánchez, M.; Álvarez Tamayo, R. I.; Pottiez, O.; Kuzin, E. A.; Ibarra-Escamilla, B.; Barcelata Pinzón, A.

    2014-06-01

    In this paper a linear cavity Erbium doped fiber (EDF) laser based in a fiber Bragg grating (FBG) and a fiber optical loop mirror with a high birefringence fiber in the loop (Hi-Bi FOLM) is used as a strain sensor. The Fabry-Perot cavity is formed by the FBG and the Hi-Bi FOLM, used as a measurement system of strain variations produced on the FBG, used as a strain sensor device. Usually, fiber laser sensor experimental setups determine the measured variable magnitude by using of an optical spectrum analyzer (OSA). Hi-Bi FOLM transmission spectrum wavelength displacement by fiber loop temperature variations measurement can be an attractive application exploiting the characteristics of FOLM transmission spectrum behavior due to Hi-Bi fiber loop temperature variations to determine the FBG strain applied through the maximal optical power monitoring by simple use of a photodetector and a temperature meter.

  11. 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.

  12. Sensitive strain sensor based on regenerated microfiber Bragg grating for high temperature environment

    NASA Astrophysics Data System (ADS)

    Ran, Yang; Gao, Shuai; Jin, Long; Sun, Li-Peng; Huang, Yun-Yun; Li, Jie; Guan, Baiou

    2015-07-01

    In this paper, an abnormal grating evolution was recorded during microfiber Bragg grating (mFBG) inscription under 193nm excimer laser. Within 20 minutes exposing, a Type IIa FBG could be obtained with above 20dB strength in 8.5 μm microfiber. This regenerated mFBG had good survival ability against high temperature up to 800 °C. Moreover, the strain response of the regenerated grating was enlarged by the microfiber structure. Thus, highly sensitive strain sensor with considerable temperature resistance could be obtained, which had potential applications in gas/oil and aerospace territory.

  13. [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. PMID:27400537

  14. Novel FBG interrogation technique for achieving < 100 nɛ accuracies at remote distances > 70 km

    NASA Astrophysics Data System (ADS)

    Farrell, Tom; O'Connor, Peter; Levins, John; McDonald, David

    2005-06-01

    Due to the development of Fibre Bragg Grating sensors for the measurement of temperature, strain and pressure many markets can benefit from optical technology. These markets are the oil and gas industry, structural and civil engineering, rail and aerospace to name a few. The advantages of using optical sensing technology are that high accuracy measurements can be performed with a passive optical system. By running one fibre along the structure or down the well, multiple points along the fibre can be tested to measure strain, temperature and pressure. Of importance with these systems is the reach that can be obtained while maintaining accuracy. A major problem with long reach system is the back reflection due to SBS and Rayleigh scattering processes which reflect part of the laser light back into the receiver which affect the sensitivity of system. This paper shows a technique to enable a reach of >70km by using a tunable laser and receiver. Techniques for the suppression of receiver noise from SBS and Raleigh scattering are implemented. In addition polarisation dependence of the FBG is considered and results of techniques to limit the effect of polarisation at long and short reaches are shown.

  15. High-precision thermal strain measurements using surface-mounted fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Mueller, Uwe C.; Both, Jan; Roths, Johannes; Baier, Horst

    2010-03-01

    Thermal strain measurements by fiber Bragg grating (FBG) sensors mounted onto different host materials are demonstrated for low coefficients of thermal expansion (CTE). Such low CTEs are typically found in carbon fiber reinforced plastics (CFRP). This work has application potential for FBG sensor networks in the highprecision control of thermal deformations in structures or in curing monitoring. For this purpose, a thermal error model of the FBG sensor, which accounts for the thermo-optic coefficient and the thermal expansion of the FBG, was characterized experimentally. The error-model characterization method is based on reference measurements of FBGs bonded to ZERODUR ceramics. Using this error model, thermal strain can be measured by surface-mounted FBGs on any given host structure using an external temperature reference and the FBG's wavelength shift. This method is demonstrated successfully for unidirectional layers of CFRP with a CTE of -0.4 . 10-6 1/K in fiber direction and for steel (316 Ti), which is commonly used in cryogenic applications. Measurements are performed for temperatures from 100K to 320K and the results are verified by high-precision dilatometer measurements. Accuracy limits of the FBG-based thermal strain measurements are discussed, as well as the minimization of errors induced by the FBG's structural interface. Further, the reduction of errors in the adhesive bonding is discussed. This work expands the understanding of the separation of thermal and mechanical effects in the signals obtained by FBGs.

  16. 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. PMID:26072789

  17. Temperature-independent accelerometer with a strain-chirped fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Li, Lan; Dong, Xinyong; Zhou, Wenjun; Sun, Yiling

    2009-11-01

    A novel fiber optic accelerometer is proposed and demonstrated. The sensing mechanism is based on the measurement of bandwidth and optical power of a strain-chirped fiber Bragg grating (FBG). An initially-uniform FBG is glued with a slanted direction onto the lateral surface of a simply-supported beam. Two masses are fixed on the top and bottom surfaces in the middle of the beam respectively, which can transfer the vertical acceleration to the deflection of the beam. Therefore, deflection induced nouniform strain is applied along the sensing FBG and makes it chirped. Experimental results show that 3-dB bandwidth and reflected optical power of the strain-chirped FBG responds to acceleration sensitively. The achieved sensitivities are up to 0.4 nm/g and 4.57 μW/g respectively in the linear range. Furthermore, this sensor is very cost-effective and inherently insensitive to temperature due to the simple demodulation method.

  18. Genetic algorithm-support vector regression for high reliability SHM system based on FBG sensor network

    NASA Astrophysics Data System (ADS)

    Zhang, XiaoLi; Liang, DaKai; Zeng, Jie; Asundi, Anand

    2012-02-01

    Structural Health Monitoring (SHM) based on fiber Bragg grating (FBG) sensor network has attracted considerable attention in recent years. However, FBG sensor network is embedded or glued in the structure simply with series or parallel. In this case, if optic fiber sensors or fiber nodes fail, the fiber sensors cannot be sensed behind the failure point. Therefore, for improving the survivability of the FBG-based sensor system in the SHM, it is necessary to build high reliability FBG sensor network for the SHM engineering application. In this study, a model reconstruction soft computing recognition algorithm based on genetic algorithm-support vector regression (GA-SVR) is proposed to achieve the reliability of the FBG-based sensor system. Furthermore, an 8-point FBG sensor system is experimented in an aircraft wing box. The external loading damage position prediction is an important subject for SHM system; as an example, different failure modes are selected to demonstrate the SHM system's survivability of the FBG-based sensor network. Simultaneously, the results are compared with the non-reconstruct model based on GA-SVR in each failure mode. Results show that the proposed model reconstruction algorithm based on GA-SVR can still keep the predicting precision when partial sensors failure in the SHM system; thus a highly reliable sensor network for the SHM system is facilitated without introducing extra component and noise.

  19. 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. PMID:24206354

  20. A novel high-sensitivity FBG pressure sensor

    NASA Astrophysics Data System (ADS)

    Yao, Zhenhua; Fu, Tao; Leng, Jinsong

    2007-07-01

    A novel pressure sensor based on FBG is designed in this paper. Not only in normal environment, also does it accurately work in water and petrol where other conventional sensors can not work normally. In this paper, the principle of the novel sensor is introduced, and two experiments are further performed: One is keeping the sensor flatly in the gastight silo whose pressure is supplied by an air compressing engine, and the other one is keeping the sensor in liquid. The analysis of the result data demonstrates that the sensor possesses high sensitivity, high linearity, high precision and repeatability. Its experimental linearity and sensitivity approach 0.99858 and 5.35×10 -3MPa -1, respectively. It is also discussed using the sensor to measure the volume in tank.

  1. 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. PMID:26698733

  2. Adherence of Bilophila wadsworthia to cultured human embryonic intestinal cells.

    PubMed

    Gerardo, S H; Garcia, M M; Wexler, H M; Finegold, S M

    1998-02-01

    Adherence of Bilophila wadsworthia to the cultured human embryonic intestinal cell line, Intestine 407 (Int 407), varied among the strains tested from strongly adherent (76-100% cells positive for one or more adherent bacteria) to non- or weakly adherent (0-25% positive cells). Although negative staining revealed that infrequent cells of an adherent strain, WAL 9077, the adherent type-strain, WAL 7959, and a non-adherent strain, WAL 8448, expressed loosely associated fimbrial structures, a role for these structures in adhesion could not be confirmed with either scanning or thin-section electron micrography. Ruthenium red staining of thin-section preparations and subsequent electron microscopy failed to reveal an extensive extracellular polysaccharide layer. SDS-PAGE analysis of crude outer membrane fractions of WAL 9077 and WAL 8448 demonstrated clear differences in their major and minor outer membrane protein components. Thus, we postulate that the adherence of B. wadsworthia to Int 407 cells is mediated by an outer membrane or cell wall component. PMID:16887620

  3. A high sensitive fiber Bragg grating(FBG) geophone detecting system

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Yu; Qi, Hai-Feng; Song, Guang-Dong; Wang, Chang; Liu, Tong-Yu

    2012-02-01

    A high sensitive fiber Bragg grating (FBG) geophone detecting system based on narrow line width distributed feedback (DFB) laser is realized by using filtering demodulation. Sensitivity of FBG geophone lies on the structure of the sensor shell and the shape of the reflectivity spectrum of FBG. Experiments on the detecting system's frequency character have been done. Results show that this geophone can detect the smallest acceleration of 1mm/s2 with a flat response from 5Hz to 40Hz.. The experiments on coal mine exhibit that the geophone can be used to measure microseismic signals. The detecting system shows great prospect in micro-seismic detection, and geological disasters detecting.

  4. A sliding-mode-based observer to identify faults in FBG sensors embedded in composite structures

    NASA Astrophysics Data System (ADS)

    Cazzulani, Gabriele; Cinquemani, Simone; Ronchi, Marco

    2016-04-01

    Optical strain gauges, such as Fiber Bragg Gratings (FBG), have a great potential for smart structures, thanks to their small transversal size and the possibility to make an array of many sensors. They can be embedded in composite structures and their effect on the structure is nearly negligible. These advantages make them very interesting in the field of active vibration suppression. Unfortunately their low reliability is an obstacle to their use in such applications. For this reason, this paper introduces a fault identification algorithm to identify online those sensors which are not working correctly. The algorithm is based on the use of a sliding mode observer to estimate the coherence of measurements, and then to highlight possible faults. Once identified, the corresponding sensors can be excluded from the feedback loop of the control algorithm to avoid unwanted behaviors or instabilities. Numerical and experimental tests have been carried out on a carbon fiber structure considering different fault conditions. Results show it is possible to identify the faulty sensors and thus improve the signals used in the feedback loop.

  5. High-speed and long-time FBG interrogation system using wavelength swept laser

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuya; Shinoda, Yukitaka

    2015-05-01

    The purpose of this research is the development of a system for fabricating high-speed and long-time measurements of wide-band vibration using fiber Bragg gratings (FBGs) to determine the health of structures. We developed a real-time FBG interrogation system using wavelength swept laser. This system can perform real-time measurement of reflected wavelength from a multiple FBG at a temporal resolution of 0.1 ms. The authors also constructed a database system for managing the data obtained from high-speed and long-time measurement. This database system manages data using a relational database and transfers information on FBG reflected wavelengths obtained from this measurement system via the local network. We have demonstrated that this system is able to measure reflected wavelengths from a multipoint FBG at a temporal resolution of 0.1 ms over 24 hours, it was shown that this system could also monitor instantaneously applied high-speed vibrations.

  6. Integrated FBG sensors interrogator in silicon photonic platform using active interferometer monitoring

    NASA Astrophysics Data System (ADS)

    Marin, Y. E.; Nannipieri, T.; Di Pasquale, F.; Oton, C. J.

    2016-05-01

    We experimentally demonstrate the feasibility of Fiber Bragg Grating sensors interrogation using integrated unbalanced Mach-Zehnder Interferometers (MZI) and phase sensitive detection in silicon-on-insulator (SOI) platform. The Phase- Generated Carrier (PGC) demodulation technique is used to detect phase changes, avoiding signal fading. Signal processing allows us to extract the wavelength shift from the signal patterns, allowing accurate dynamic FBG interrogation. High resolution and low cost chips with multiple interrogators and photodetectors on board can be realized by exploiting the advantages of large scale fabrication capabilities of well-established silicon based industrial infrastructures. Simultaneous dynamic reading of a large number of FBG sensors can lead to large volume market applications of the technology in several strategic industrial fields. The performance of the proposed integrated FBG interrogator is validated by comparing with a commercial FBG readout based on a spectrometer and used as a reference.

  7. V-groove-based compact FBG package for thermal tuning and mechanical stability

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Fang, Wei; Wang, Di; Chen, Di-Jun; Cai, Hai-Wen; Qu, Rong-Hui

    2016-04-01

    We demonstrated a V-groove-based fiber Bragg grating (FBG) package that has been glue-filled and cured to make it a bulky component with much improved mechanical stability. The V-groove can be executed with many types of materials including plastics, ceramics, semiconductors, and metals, providing an easy method for redesigning the thermal tuning performance of FBGs by selecting among a wide variety of materials and processes. We achieved more than 10-nm thermal wavelength tuning and thermal sensitivity ranging from 15 to 160 pm/K. The original FBG spectrum can be maintained without any degradation because the fiber is buried in the V-groove. The compact package does not increase the original grating length and turns the FBG into a planar waveguide grating, improving FBG applications in telecommunications, external cavity lasers, and sensing areas.

  8. Fiber Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    NASA Astrophysics Data System (ADS)

    Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abdelalim, A. A.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Ahmed, W.; Aleksandrov, A.; Aly, R.; 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.; Elmetenawee, W.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hassan, A.; 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.; 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.; Masod, R.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohamed, S.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Passamonti, L.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; 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.; 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.

    2016-07-01

    A novel approach which uses Fiber Bragg Grating (FBG) sensors has been utilized to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

  9. 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.

  10. 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

    2011-11-01

    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.

  11. Adherence of Borrelia burgdorferi to granulocytes of different animal species.

    PubMed

    Grassmann, B; Kopp, P A; Schmitt, M; Blobel, H

    1997-04-01

    Adherence of 4 Borrelia (B.) burgdorferi strains (z7/22, z7/27, z7/41, PBi) to polymorphonuclear granulocytes from different domestic animals (horses, cattle, sheep, dogs) was investigated. All 4 strains adhered to the granulocytes. Binding assays indicated that the adherence occurred between structures on the surface of the borreliae ("binding-sites") and on the membranes of the granulocytes ("receptors"). The "receptors" consisted of 4 fractions (A, B, C, and D) with components differing in molecular weight (MW) and binding activity for proteins on the surface of B. burgdorferi. Fraction A (MW 80000) had the highest binding activity for B. burgdorferi. PMID:9144911

  12. FBG1 Is the Final Arbitrator of A1AT-Z Degradation

    PubMed Central

    Wen, John H.; Wen, Hsiang; Gibson-Corley, Katherine N.; Glenn, Kevin A.

    2015-01-01

    Alpha-1 antitrypsin deficiency is the leading cause of childhood liver failure and one of the most common lethal genetic diseases. The disease-causing mutant A1AT-Z fails to fold correctly and accumulates in the endoplasmic reticulum (ER) of the liver, resulting in hepatic fibrosis and hepatocellular carcinoma in a subset of patients. Furthermore, A1AT-Z sequestration in hepatocytes leads to a reduction in A1AT secretion into the serum, causing panacinar emphysema in adults. The purpose of this work was to elucidate the details by which A1AT-Z is degraded in hepatic cell lines. We identified the ubiquitin ligase FBG1, which has been previously shown to degrade proteins by both the ubiquitin proteasome pathway and autophagy, as being key to A1AT-Z degradation. Using chemical and genetic approaches we show that FBG1 degrades A1AT-Z through both the ubiquitin proteasome system and autophagy. Overexpression of FBG1 decreases the half-life of A1AT-Z and knocking down FBG1 in a hepatic cell line, and in mice results in an increase in ATAT. Finally, we show that FBG1 degrades A1AT-Z through a Beclin1-dependent arm of autophagy. In our model, FBG1 acts as a safety ubiquitin ligase, whose function is to re-ubiquitinate ER proteins that have previously undergone de-ubiquitination to ensure they are degraded. PMID:26295339

  13. Enhancing adherence through education.

    PubMed

    Smrtka, Jennifer; Caon, Christina; Saunders, Carol; Becker, Brenda L; Baxter, Nancy

    2010-10-01

    The treatment of multiple sclerosis (MS) has advanced greatly since the introduction of disease-modifying therapies (DMTs) in the early 1990s. Although the DMTs have exhibited significant efficacy in relapsing-remitting MS and other forms of the disease, the degree of benefit depends heavily on patient adherence to recommended regimens. This article addresses some of the most pressing areas of unmet need in educating advanced-practice nurses, neurologists, patients, and support care partners regarding strategies that can overcome obstacles to adherence. The observations presented here are based on clinical experience with real-life cognitive, psychosocial, and cultural impediments to adherence. The article also explores the ways in which adherence may be affected by emerging therapies for MS (such as oral agents) as well as the educational needs that will arise with the further evolution of MS care. PMID:21049830

  14. Strain gradient chirp of uniform fiber Bragg grating without shift of central Bragg wavelength

    NASA Astrophysics Data System (ADS)

    Dong, Xinyong; Guan, Bai-Ou; Yuan, Shuzhong; Dong, Xiaoyi; Tam, Hwa-Yaw

    2002-02-01

    A novel technique to introduce large linear chirp to an uniform fiber Bragg grating (FBG) is realized by gluing the grating in a slanted direction onto the side face of a simple supported beam. Strain gradient is formed along the length of the grating when the beam is bent, and produces a linear variation in the grating pitch. This permits a tunable chirp without central wavelength shift. The maximum bandwidth of the chirped FBG produced was 11.32 nm.

  15. Adherence to Insulin Therapy.

    PubMed

    Sarbacker, G Blair; Urteaga, Elizabeth M

    2016-08-01

    IN BRIEF Six million people with diabetes use insulin either alone or in combination with an oral medication. Many barriers exist that lead to poor adherence with insulin. However, there is an underwhelming amount of data on interventions to address these barriers and improve insulin adherence. Until pharmacological advancements create easier, more acceptable insulin regimens, it is imperative to involve patients in shared decision-making. PMID:27574371

  16. Research of narrow line-width Er3+-doped fiber ring laser with FBG F-P etalon and FBG Sagnac loop

    NASA Astrophysics Data System (ADS)

    Ou, Zhonghua; Dai, Zhiyong; Wu, Bo; Zhang, Lixun; Peng, Zengshou; Liu, Yongzhi

    2008-12-01

    A novel method of narrow line-width Er3+-doped fiber ring laser based on FBG F-P etalon and FBG Sagnac loop is presented in this paper. The all-fiber single frequency and narrow line-width Er3+-doped fiber ring laser has been designed in which two 976 nm laser diodes are used as the pump sources, the high concentration Er3+-doped fiber as the gain medium, the fiber Faraday rotator is adopted to eliminate the spatial hole burning effect, the FBG F-P etalon and FBG Sagnac loop filter can discriminate and select laser longitudinal modes efficiently. The experiment system using 3m long Er3+-doped fibers is presented, when the maximum pump power of two 976nm laser diodes is 146mW, the fiber laser exhibits 16mW threshold and stable single frequency 1550nm laser with the output powers of 45mW is acquired, and the slope efficiency is about 34.6%. The 3dB line-width is less than 9.3 kHz, measured by the delayed selfheterodyne method with 15km single-mode fiber, and no mode hopping is observed. The fiber laser has the advantages of simple structure, high efficiency and high reliability and it has great potential applications in the fields of optical fiber sensing system.

  17. New technique for fabrication of low loss high temperature stable high reflectivity FBG sensor arrays

    NASA Astrophysics Data System (ADS)

    Mihailov, Stephen J.; Grobnic, Dan; Walker, Robert B.; Hnatovsky, Cyril A.; Ding, Huimin; Coulas, David; Lu, Ping

    2016-05-01

    Fiber Bragg gratings (FBG) arrays in silica based optical fibers are increasingly used in applications involving system monitoring in extreme high temperature environments. Where operational temperatures are < 600 °C, traditional UVlaser inscribed FBGs are not appropriate since the induced Type I index change is erased. Instead two competing FBG technologies exist: 1) regenerative FBGs resulting from high temperature annealing of a UV-laser written grating in a hydrogen loaded fiber and 2) FBGs written with femtosecond infrared pulse duration radiation (fs-IR), either using the point-by-point method or using the phase mask approach. Regenerative gratings possess low reflectivity and are cumbersome to produce, requiring high temperature processing in an oxygen free environment. Multiple pulse Type II femtosecond IR laser induced gratings made with a phase mask, while having very good thermal stability, also tend to have high insertion loss (~ 1dB/grating) limiting the number of gratings that can be concatenated in a sensor array. Recently it has been shown that during multiple pulse type II thermally stable fs-IR FBG production, two competing process occur: an initial induced fs-IR type I FBG followed by a thermally stable high insertion loss type II FBG. In this paper, we show that if only a type I FBG is written using type II intensity conditions but limited numbers of pulses and then annealed above 600 °C, the process results in a type II grating that is stable up to 1000 °C with very low insertion loss ideal for an FBG sensor array.

  18. FBG pressure sensor of high pressure electric oil pumps for prestressing

    NASA Astrophysics Data System (ADS)

    Guo, Zhenwu; Liu, Guangwei; Meng, Qingbin; Ge, Fuwei; Li, Weixiang

    2013-03-01

    Prestressed concrete structure is getting more and more extensive application in architecture, hydraulic engineering and traffic engineering because of its significant advantages of crack later or not cracks completely. It is an internal stress concrete structure that a certain force relies on prestressing tendons. The effectivity of the prestressing tendon in concrete structure is directly related to the reliability, applicability and viability of the whole concrete structure. So it is a key program to apply accurate prestress to the prestressing tendon. According to the pressure sensing principle of the fiber Bragg grating (FBG), a circular plate diaphragm-based FBG sensor for high pressure electric oil pumps that is the pressure source device of the prestressed concrete structure was presented. To overcome the cross sensitivity of temperature and pressure, two FBGs were integrated in the sensor, one of the FBGs isolated from the pressure is used as temperature compensation grating, it is called temperature-FBG comparing to another FBG called pressure-FBG. The elastic diaphragm was chosen as the pressure sensing element whose distortion displace is proportional to the difference of the two sides' pressure of the diaphragm. A certain stress is applied to the pressure-FBG which is stuck to the center of the diaphragm, and then the reflection wavelength of the pressure-FBG is inverse proportional to load of the diaphragm. The results indicated that the linearity is up to 99.99%, and the pressure sensitivity coefficient is 0.024nm/MPa within the measurement scope of 0-70MPa.

  19. Design and application of a fiber Bragg grating strain sensor with enhanced sensitivity in the small-scale dam model

    NASA Astrophysics Data System (ADS)

    Ren, Liang; Chen, Jianyun; Li, Hong-Nan; Song, Gangbing; Ji, Xueheng

    2009-03-01

    Accurate measurement of strain variation and effective prediction of failure within models have been major objectives for strain sensors in dam model tests. In this paper, a fiber Bragg grating (FBG) strain sensor with enhanced strain sensitivity that is packaged by two gripper tubes is presented and applied in the seismic tests of a small-scale dam model. This paper discusses the principle of enhanced sensitivity of the FBG strain sensor. Calibration experiments and reliability tests were conducted to evaluate the sensor's strain transferring characteristics on plates of different material. This paper also investigates the applicability of the FBG strain sensors in seismic tests of a dam model by conducting a comparison between the test measurements of FBG sensors and analytical predictions, monitoring the failure progress and predicting the cracking inside the dam model. Results of the dam model tests prove that the FBG strain sensor has the advantages of small size, high precision, and embeddability. It has a promising potential in the cracking and failure monitoring and identification of the dam model.

  20. Adherence to Sublingual Immunotherapy.

    PubMed

    Incorvaia, Cristoforo; Mauro, Marina; Leo, Gualtiero; Ridolo, Erminia

    2016-02-01

    Adherence is a major issue in any medical treatment. Allergen immunotherapy (AIT) is particularly affected by a poor adherence because a flawed application prevents the immunological effects that underlie the clinical outcome of the treatment. Sublingual immunotherapy (SLIT) was introduced in the 1990s, and the early studies suggested that adherence and compliance to such a route of administration was better than the traditional subcutaneous route. However, the recent data from manufacturers revealed that only 13% of patients treated with SLIT reach the recommended 3-year duration. Therefore, improved adherence to SLIT is an unmet need that may be achieved by various approaches. The utility of patient education and accurate monitoring during the treatment was demonstrated by specific studies, while the success of technology-based tools, including online platforms, social media, e-mail, and a short message service by phone, is currently considered to improve the adherence. This goal is of pivotal importance to fulfill the object of SLIT that is to modify the natural history of allergy, ensuring a long-lasting clinical benefit, and a consequent pharmaco-economic advantage, when patients complete at least a 3-year course of treatment. PMID:26758865

  1. Optical fiber sensors for measurement strain and vibration

    NASA Astrophysics Data System (ADS)

    Mikel, Bretislav; Helan, Radek; Buchta, Zdenek; Holík, Milan; Jelinek, Michal; Cip, Ondrej

    2015-01-01

    We present optical fiber sensors to measurement strain and vibration. The sensors are based on fiber Bragg gratings (FBG). We prepared construction of strain sensors with respect to its implementation on the outer surface of concrete structures and with compensation of potential temperature drifts. These sensors are projected with look forward to maximal elongation and strength which can be applied to the sensor. Each sensor contains two optical fibers with FBGs. One FBG is glued into the sensor in points of fixation which are in the line with mounting holes. This FBG is prestressed to half of measurement range, than the stretching and pressing can be measured simultaneously by one FBG. The second FBG is placed inside the sensor without fixation to measure temperature drifts. The sensor can be used to structure health monitoring. The sensors to measurement vibration are based on tilted fiber Bragg grating (TFBG) with fiber taper. The sensor uses the TFBG as a cladding modes reflector and fiber taper as a bend-sensitive recoupling member. The lower cladding modes (ghost), reflected from TFBG, is recoupled back into the fiber core via tapered fiber section. We focused on optimization of TFBG tilt angle to reach maximum reflection of the ghost and taper parameters. In this article we present complete set-up, optical and mechanical parameters of both types of sensors.

  2. 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

  3. Fabrication and characterisation of FBG sensors in low loss polymer optical fibre

    NASA Astrophysics Data System (ADS)

    Lacraz, Amédée.; Theodosiou, Andreas; Polis, Michalis; Kalli, Kyriacos

    2016-05-01

    In this paper, we report on an effective way to locally alter the refractive index of a low-loss polymer optical fibre (POF), in order to fabricate novel fibre optical sensors. Such refractive index modifications, if reproduced periodically, create fibre Bragg gratings (FBGs) that find diverse applications in telecommunications and sensing. With a femtosecond laser set-up, we were able to inscribe refractive index changes in the core of the fibre on an area as small as a μm2. This technique can be effectively used to produce FBGs with a tailored length and strength and, so, with desired optical properties. The fibre used was a large core, graded index, multimode perfluorinated fibre. FBGs resonate at different wavelengths depending on the mode distribution in multimode fibres, because the effective refractive index depends on the spatial distribution of the light inside the core. Therefore, the reflection spectrum from the grating degenerates into multiple resonances, each associated with a different mode. The detection of the reflected modes was performed with a custom made software that was able to track a specific reflected mode even when the FBG underwent perturbation, such as temperature or strain changes. Moreover, a key advantage of low-loss fibre is the possibility to use long lengths of fibre and to be able to inscribe several FBGs in a single piece of fibre. With our detection system, we managed to track the perturbation of individual FBGs in a fibre array of multiple gratings. The combination of our femtosecond inscription setup and a mode detection system is encouraging for the development of low loss POF sensing devices.

  4. 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

    2015-01-01

    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

  5. Experimental qualification by extensive evaluation of fibre optic strain sensors

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Kusche, Nadine; Schukar, Vivien G.; Münzenberger, Sven; Habel, Wolfgang R.

    2013-09-01

    Fibre optic strain sensors used in practical applications have to provide reliable measurements. Therefore, the applied sensor and the sensor systems must be validated experimentally. This can be achieved with facilities which use physically independent measurement systems in order to avoid the influences caused by the application of a reference sensor. This paper describes the testing methods of the specially developed validation facility KALFOS for the qualification and evaluation of surface-applied strain sensors. For reliable sensor results, the performance of fibre optic strain patches with and without FBG under combined thermal and mechanical loading was investigated. Additionally, the strain gauge factor of the fibre optic strain patches with FBG was determined experimentally and compared to the specified strain gauge factor. These results will be the basis for the development of guidelines and standards concerning the application of the sensors.

  6. Concept and design of an FBG emulator for a scanning laser-based fiber optic interrogator

    NASA Astrophysics Data System (ADS)

    Kuhenuri, Nader; Putzer, Philipp; Koch, Alexander W.; Obermaier, Johannes; Schweyer, Sebastian; Hurni, Andreas

    2014-06-01

    The Hybrid Sensor Bus is a space-borne temperature monitoring system for telecommunication satellites com­ bining electrical and fiber-optical Fiber Bragg Grating (FBG) sensors. Currently, there is no method available for testing the functionality and robustness of the system without setting up an actual sensor-network implying numerous FBG sensors in which each has to be heated/cooled individually. As a verification method of the mentioned system, FBG reflection based scanning laser interrogator, an FBG­ emulator is implemented to emulate the necessary FBG sensors. It is capable of immediate emulation of any given FBG spectrum, thus, any temperature. The concept provides advantages like emulating different kinds of FBGs with any peak shape, variable Bragg-wavelength λB, maximal-reflectivity τmax, spectral-width and degradation characteristics. Further, it facilitates an efficient evaluation of different interrogator peak-finding algorithms and the capability of emulating up to 10000 sample points per second is achieved. In the present paper, different concepts will be discussed and evaluated yielding to the implementation of a Variable Optical Attenuator (VOA) as the main actuator of the emulator. The actuator choice is further restricted since the emulator has to work with light in unknown polarization state. In order to implement a fast opto-ceramic VOA, issues like temperature dependencies, up to 200 V driving input and capacitive load have to be overcome. Furthermore, a self-calibration procedure mitigates problems like attenuation losses and long-term drift.

  7. Nondestructive inspection of CFRP adhesively bonded joints using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Webb, S.; Shin, P.; Peters, K.; Selfridge, R.; Schultz, S.

    2013-05-01

    One challenging need for inspection capabilities is in adhesively bonded joints between composite components, a common location of premature failure in aerospace structures. In this work we demonstrate that dynamic, full spectral scanning of FBG sensors embedded in the adhesive bond can identify changes in bond quality through the measurement of non-linear dynamics of the joint. Eighteen lap joint specimens were fabricated with varying manufacturing quality. Ten samples also included fiber Bragg grating (FBG) sensors embedded in the adhesive bond for real-time inspection during a simulated flight condition of these single-lap joints. Prior to testing, pulse phase thermography imaging of the pristine specimens revealed defects such as air bubbles, adhesive thickness variations, and weak bonding surface between the laminate and adhesive. The lap joint specimens were then subjected to fatigue loading, with regular interrogation of the FBG sensors at selected load cycle intervals. The FBG data was collected during vibration loading of the lap joint to represent an in-flight environment. Changes in the lap joint dynamic response, including the transition to non-linear responses, were measured from both the full-spectral and peak wavelength FBG data. These changes were correlated to initial manufacturing defects and the progression of fatigue-induced damage independently measured with pulse phase imaging and visual inspections of the failure surfaces.

  8. 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.

  9. Enhanced strain and temperature sensing by reduced graphene oxide coated etched fiber Bragg gratings.

    PubMed

    S, Sridevi; Vasu, K S; Asokan, S; Sood, A K

    2016-06-01

    This Letter reports on an etched fiber Bragg grating (eFBG) sensor coated with reduced graphene oxide (RGO) having enhanced sensitivity for physical parameters such as strain and temperature. The synergetic effect of the changes in grating pitch and refractive index of RGO with change in temperature or strain enhances the shift in Bragg wavelength (λB). The RGO-coated eFBG sensors exhibit a strain sensitivity of 5.5 pm/μϵ (∼5 times that of bare fiber Bragg gratings) and temperature sensitivity of 33 pm/°C (∼3 times that of bare fiber Bragg gratings). The resolutions of ∼1  μϵ and ∼0.3°C have been obtained for strain and temperature respectively, using RGO-coated eFBG sensors. PMID:27244425

  10. Adherence to treatment in adolescents

    PubMed Central

    Taddeo, Danielle; Egedy, Maud; Frappier, Jean-Yves

    2008-01-01

    Health care professionals must be alert to the high prevalence of low adherence to treatment during adolescence. Low adherence increases morbidity and medical complications, contributes to poorer quality of life and an overuse of the health care system. Many different factors have an impact on adherence. However, critical factors to consider in teens are their developmental stage and challenges, emotional issues and family dysfunction. Direct and indirect methods have been described to assess adherence. Eliciting an adherence history is the most useful way for clinicians to evaluate adherence, and could be the beginning of a constructive dialogue with the adolescent. Interventions to improve adherence are multiple – managing mental health issues appropriately, building a strong relationship, customizing the treatment regimen if possible, empowering the adolescent to deal with adherence issues, providing information, ensuring family and peer support, and motivational enhancement therapy. Evaluation of adherence at regular intervals should be an important aspect of health care for adolescents. PMID:19119348

  11. 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.

  12. Fully distributed chirped FBG sensor and application in laser-induced interstitial thermotherapy

    NASA Astrophysics Data System (ADS)

    Li, Chenglin; Chen, Na; Chen, Zhenyi; Wang, Tingyun

    2009-11-01

    In the laser induced interstitial thermotherapy (LITT), real-timely detecting the temperature distribution of the cured tissue is a bottleneck. In this paper, a fully distributed chirped Fiber Bragg grating (FBG) sensor, which is of small size, immune from electromagnetic interference (EMI) and high sensitivity, is proposed to solve this problem. An experiment simulation of LITT is set up, and only one chirped FBG is used to detect the dynamic spectral variation with different laser power. Meanwhile, a high-efficiency spectra inversion algorithm named MSAE of FBG is utilized to demodulate the system and obtain the temperature distribution. The spatial resolution is 0.25mm and the running time of demodulation is tens of seconds, which can help doctors control the laser parameters such as the laser power and the treatment time to guarantee the security of the therapy.

  13. Noise reduction of FBG sensor signal by using a wavelet transform

    NASA Astrophysics Data System (ADS)

    Cho, Yo-Han; Song, Minho

    2011-05-01

    We constructed a FBG (fiber Bragg grating) sensor system based on a fiber-optic Sagnac interferometer. A fiber-optic laser source is used as a strong light source to attain high signal-to-noise ratio. However the unstable output power and coherence noises of the fiber laser made it hard to separate the FBG signals from the interference signals of the fiber coils. To reduce noises and extract FBG sensor signals, we used a Gaussian curve-fitting and a wavelet transform. The wavelet transform is a useful tool for analyzing and denoising output signals. The feasibility of the wavelet transform denoising process is presented with the preliminary experimental results, which showed much better accuracy than the case with only the Gaussian curve-fitting algorithm.

  14. Design of FBG En/decoders in Coherent 2-D Time-polarization OCDMA Systems

    NASA Astrophysics Data System (ADS)

    Hou, Fen-fei; Yang, Ming

    2012-12-01

    A novel fiber Bragg grating (FBG)-based en/decoder for the two-dimensional (2-D) time-spreading and polarization multiplexer optical coding is proposed. Compared with other 2-D en/decoders, the proposed en/decoding for an optical code-division multiple-access (OCDMA) system uses a single phase-encoded FBG and coherent en/decoding. Furthermore, combined with reconstruction-equivalent-chirp technology, such en/decoders can be realized with a conventional simple fabrication setup. Experimental results of such en/decoders and the corresponding system test at a data rate of 5 Gbit/s demonstrate that this kind of 2-D FBG-based en/decoders could improve the performances of OCDMA systems.

  15. Filamentous hemagglutinin has a major role in mediating adherence of Bordetella pertussis to human WiDr cells.

    PubMed Central

    Urisu, A; Cowell, J L; Manclark, C R

    1986-01-01

    [35S]methionine-labeled Bordetella pertussis adhered to monolayers of WiDr cells, an epitheliumlike cell line from a human intestinal carcinoma. Adherence was proportional to the density of the WiDr cells and to the concentration of B. pertussis in the assay. Adherence of virulent phase I strains Tohama phase I, 114, and BP338 was much greater than adherence of avirulent strains Tohama phase III and 423 phase IV. Mutants deficient in the production of the filamentous hemagglutinin (FHA) were hemagglutination negative and adhered to WiDr cells much less efficiently than the parent strains. Preincubation of B. pertussis cells with FHA increased their hemagglutination activity and adherence to WiDr cells. Goat antibody to FHA inhibited, in a dose-dependent manner, the adherence of strain Tohama I but not the adherence of FHA-deficient mutant Tohama 325. At similar protein concentrations, normal goat antibody, goat antibody to pertussis toxin, or the Fab fragments of goat antibody to serotype 2 fimbriae had no effect on adherence. Also, an FHA-positive strain without fimbriae showed high adherence, while a fimbriated FHA-deficient mutant adhered poorly. Our data indicate that FHA plays a major role in adherence of B. pertussis to human WiDr cells. Fimbriae do not appear to mediate attachment of B. pertussis to WiDr cells. PMID:2872165

  16. Research on construction monitoring of the Third Nanjing Yangtze Bridge using FBG sensors

    NASA Astrophysics Data System (ADS)

    Hu, Qingli; Zhou, Zhi; Ou, Jinping

    2007-01-01

    Construction monitor is an important way to ensure safety and economical efficiency at construction stage of civil engineering, and monitor technique is one of the key elements to actualize the monitoring scheme. During construction of the foundation of the Third Nanjing Yangtze Bridge, FBG techniques were adopted due to complex site environment and high quality requirement of the engineering. The study group not only presented applicable embedding method of FBG sensors, but also developed monitor software according to mechanical analysis of each object. The practice demonstrates that the sensors worked well and had provided reliable data for decision-making in construction.

  17. 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.

  18. Reflective SOA fiber cavity adaptive laser source for measuring dynamic strains

    NASA Astrophysics Data System (ADS)

    Wei, Heming; Tao, Chuanyi; Krishnaswamy, Sridhar

    2016-04-01

    Smart sensors based on Optical fiber Bragg gratings (FBGs) are suitable for structural health monitoring of dynamic strains in civil, aerospace, and mechanical structures. In these structures, dynamic strains with high frequencies reveal acoustic emissions cracking or impact loading. It is necessary to find a practical tool for monitoring such structural damages. In this work, we explore an intelligent system based on a reflective semiconductor optical amplifier (RSOA)- FBG composed as a fiber cavity for measuring dynamic strain in intelligent structures. The ASE light emitted from a RSOA laser and reflected by a FBG is amplified in the fiber cavity and coupled out by a 90:10 coupler, which is demodulated by a low frequency compensated Michelson interferometer using a proportional-integral-derivative (PID) controller and is monitored via a photodetector. As the wavelength of the FBG shifts due to dynamic strain, the wavelength of the optical output from the laser cavity shifts accordingly, which is demodulated by the Michelson Interferometer. Because the RSOA has a quick transition time, the RSOA- FBG fiber cavity shows an ability of high frequency response to the FBG reflective spectrum shift, with frequency response extending to megahertz.

  19. 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.

  20. Fiber Bragg grating sensors for use in pavement structural strain-temperature monitoring

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Neng; Tang, Jaw-Luen; Chang, Hsiang-Ping

    2006-03-01

    In this paper, we describe the development and realization of a newly high-resolution temperature and strain sensor with fiber Bragg grating (FBG) technology. The FBG sensor consists of a reference fiber grating and a grating pair scheme that could offer the potential of simultaneous measurement of strain and temperature for monitoring pavement structures. Experimental results showed that measurement errors of 6 μɛ and 0.13 °C for strain and temperature could be achieved, respectively. The reliability and long-term stability for temperature measurement with this type of sensor were examined by mounting sensors on the surface of asphalt and concrete specimens. Small root mean square temperature variations (better than 1 °C) and excellent long-term stability (within 2%) were obtained. The maximum variations in temperature for 48 hours were only 1.94% and 2.32% for asphalt and concrete specimens, respectively. The feasibility of strain measurement for pavement structures was conducted by mounting the packaged sensor on the surface of an asphalt specimen under the indirect tensile loading condition. The measured strains from the packaged FBG sensor agreed linearly with applied loads. A finite-element model (FEM) was conducted to verify the strains obtained from the sensors. In comparison with experimental data and numerical results, the numerical values were all located within FBG measurement error ranges. The strain differences between measurements from the FBG sensor and FEM predictions were between 5% and 7%. This type of simple and low-cost FBG sensor is expected to benefit the developments and applications of pavement structures or transportation infrastructure.

  1. Adherence of oral streptococci to salivary glycoproteins.

    PubMed Central

    Murray, P A; Prakobphol, A; Lee, T; Hoover, C I; Fisher, S J

    1992-01-01

    We used an overlay method to study the ability of human salivary glycoproteins to serve as receptors for several strains of streptococci that colonize the oral cavity. Parotid and submandibular-sublingual salivas were collected as ductal secretions, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and transferred to nitrocellulose membranes. The resulting blots were overlaid with [35S]methionine-labeled bacteria, and salivary components to which the bacteria bound were detected by autoradiography. Potential glycoprotein receptors were identified for 8 of the 16 strains tested. In three cases (Streptococcus sanguis 72-40 and 804 and Streptococcus sobrinus OMZ176), highly specific interactions with a single salivary component were detected. Removal of sialic acid residues from the low-molecular-weight salivary mucin prevented adherence of one of these strains (S. sanguis 72-40), suggesting that this saccharide either mediates binding or is a critical component of the receptor site. In the remaining five strains (Streptococcus gordonii G9B and 10558, S. sanguis 10556, and Streptococcus oralis 10557 and 72-41), interactions with multiple salivary components, including the low-molecular-weight salivary mucin, highly glycosylated proline-rich glycoproteins, and alpha-amylase, were detected. These results suggest that some oral streptococci can bind specifically to certain of the salivary glycoproteins. The interactions identified may play an important role in governing bacterial adherence and clearance within the oral cavity. Images PMID:1729194

  2. 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. PMID:27607270

  3. Comparison of strain sensitivity of bare and structure-integrated fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Lebid, Solomija Y.; Hofmann, Detlef; Basedau, Frank; Daum, Werner

    2003-07-01

    For the last decade sensor architectures with embedded fibers found their application in large structure monitoring and proved their capability to replace existing techniques for monitoring of linear strain, temporary or permanent none-uniform strain and load, temperature, vibrations, bending, or complex strain-temperature, vibrations-temperature influences, etc. Such sensor architectures, called smart structures, use different sensing mechanisms, in one of which - fiber Bragg grating (FBG) - is applied as a sensitive element. Because of high sensitivity, absolute measurement ability, possibility to work reliable in adverse environment, such as electromagnetic fields, radiation, extreme temperature, and quick response time, FBGs are object of numerous research of leading laboratories worldwide. Some problems are still remaining in this field, although there have been some ways found to solve part of them. This paper discusses some aspects of different fixing mechanisms of FBG and provides evaluation and comparison of methods of FBG integration in sensor housing or in sensor architecture.

  4. Temperature insensitive magnetic field sensor based on an etched TCFMI cascaded with a FBG

    NASA Astrophysics Data System (ADS)

    Yan, Guofeng; Zhang, Liang; He, Sailing

    2015-08-01

    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 fluid cladding surrounding the TCFMI was used as a magnetic field-to-refractive index transducer. To depress the temperature influence on the performance of such sensors, an FBG was inscribed in the leading SMF of the TCFMI. 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/°, respectively, while the Bragg wavelength of the FBG only has a temperature sensitivity of 13.23 pm/°. By monitoring the reflection wavelength and intensity of the Bragg mode, the intensity of the magnetic field and the temperature variance can be measured, which enables magnetic field sensing under strict temperature environments. Meanwhile the reflective sensing probe is more compact and practical for applications in hard-to-reach conditions.

  5. A soft self-repairing for FBG sensor network in SHM system based on PSO-SVR model reconstruction

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoli; Wang, Peng; Liang, Dakai; Fan, Chunfeng; Li, Cailing

    2015-05-01

    Structural health monitoring (SHM) system takes advantage of an array of sensors to continuously monitor a structure and provide an early prediction such as the damage position and damage degree etc. Such a system requires monitoring the structure in any conditions including bad condition. Therefore, it must be robust and survivable, even has the self-repairing ability. In this study, a model reconstruction predicting algorithm based on particle swarm optimization-support vector regression (PSO-SVR) is proposed to achieve the self-repairing of the Fiber Bragg Grating (FBG) sensor network in SHM system. Furthermore, an eight-point FBG sensor SHM system is experimented in an aircraft wing box. For the damage loading position prediction on the aircraft wing box, six kinds of disabled modes are experimentally studied to verify the self-repairing ability of the FBG sensor network in the SHM system, and the predicting performance are compared with non-reconstruction based on PSO-SVR model. The research results indicate that the model reconstruction algorithm has more excellence than that of non-reconstruction model, if partial sensors are invalid in the FBG-based SHM system, the predicting performance of the model reconstruction algorithm is almost consistent with that no sensor is invalid in the SHM system. In this way, the self-repairing ability of the FBG sensor is achieved for the SHM system, such the reliability and survivability of the FBG-based SHM system is enhanced if partial FBG sensors are invalid.

  6. Cellular Adherence, Glucosyltransferase Adsorption, and Glucan Synthesis of Streptococcus mutans AHT Mutants

    PubMed Central

    Koga, Toshihiko; Inoue, Masakazu

    1978-01-01

    Streptococcus mutans AHT mutants M1, M2, and M13 failed to adhere to a glass surface, whereas mutants M9 and M35 exhibited decreased and increased adherence, respectively, as compared with the parent strain, when grown in sucrose broth. Extracellular glucosyltransferase prepared from glucose-grown cultures of the adherent strains (wild type, M9, and M35) induced adherence of heat-killed cells of the homologous and heterologous streptococcal strains as well as of Escherichia coli K-12 and uncoated resin particles. The glucosyltransferase was adsorbed on all the streptococcal cells and glucan-coated resins, but not on E. coli cells and the uncoated resins. Glucosyltransferase from the nonadhering mutants (M1, M2, M13) neither was significantly adsorbed on nor induced adherence of any of the cells and resins. Cell-free enzymes from the glucose-grown adherent strains produced water-soluble and water-insoluble glucans, whereas those from the nonadhering mutants produced only water-soluble glucans. Small amounts of alkali-soluble, cell-associated glucan were recovered from the sucrose-grown nonadhering mutants. Thus, the relative proportions of glucosyltransferase isozymes elaborated by the S. mutans mutants, insofar as they affect the physico-chemical properties of the glucans produced, seem to determine the adherence abilities of the cells. The adsorption of glucosyltransferase on glucan molecules on the cell surface is not required for the adherence of S. mutans, but de novo glucan synthesis is important in the adherence process. PMID:631879

  7. Evaluation of the performance of orthodontic devices using FBG sensors

    NASA Astrophysics Data System (ADS)

    Carvalho, L.; Roriz, P.; Frazão, O.; Marques, M. B.

    2015-04-01

    Cross-bite, as a malocclusion effect, is defined as a transversal changing of the upper dental arch, in relation to the lower arch, and may be classified as skeletal, dental or functional. As a consequence, the expansion of maxilla is an effective clinical treatment used to correct transversal maxillary discrepancy. The maxillary expansion is an ancient method used in orthodontics, for the correction of the maxillary athresia with posterior crossbite, through the opening of the midpalatal suture (disjunction), using orthodontic- orthopaedic devices. Same controversial discussion arises among the clinicians, about the effects of each orthodontic devices as also about the technique to be employed. The objective of this study was to compare the strain field induced by two different orthodontic devices, named disjunctor with and without a connecting bar, in an acrylic model jaw, using fiber Bragg grating sensors to measure the strain patterns. The orthodontic device disjunctor with the bar, in general, transmits higher forces and strain to teeth and maxillae, than with the disjunctor without bar. It was verified that the strain patterns were not symmetric between the left and the right sides as also between the posterior and anterior regions of the maxillae. For the two devices is also found that in addition a displacement in the horizontal plane, particularly in posterior teeth, also occurs a rotation corresponding to a vestibularization of the posterior teeth and their alveolar processes.

  8. Dynamic Response and Signal to Noise Ratio Investigation of NIR-FBG Dynamic Sensing System for Monitoring Thin- walled Composite Plate

    NASA Astrophysics Data System (ADS)

    Hafizi, Z. M.; Epaarachchi, J.

    2015-12-01

    Optical fiber systems for dynamic response measurement become an attractive study nowadays especially in the field of Structural Health Monitoring (SHM). This work presents the investigation of an optical fiber sensor system utilizing Near Infra-Red Fiber Bragg Grating (NIR-FBG) sensor for SHM of a thin-walled composite structure. In this study, a comparison between the experimental result and simulation study using finite element analysis has been presented. By comparing both results, the FBG dynamic sensing system was shown to have an excellent capability in acquiring dynamic response due to flexural wave propagations. In the meantime, a signal to noise ratio (SNR) study was also performed to several FBG dynamic sensor systems; particularly to see the comparison between NIR-FBG sensor and 1550 nm FBG sensor. Furthermore, with a proper configuration, an NIR-FBG system was proved to have better performance than the 1550 nm based FBG sensor.

  9. Reconceptualizing medication adherence: six phases of dynamic adherence.

    PubMed

    Gearing, Robin E; Townsend, Lisa; MacKenzie, Michael; Charach, Alice

    2011-01-01

    Nonadherence is the Achilles' heel of effective psychiatric treatment. It affects the resolution of mental health symptoms and interferes with the assessment of treatment response. The meaning of the term adherence has evolved over time and is now associated with a variety of definitions and measurement methods. The result has been a poorly operationalized and nonstandardized term that is often interpreted differently by providers and patients. Drawing extensively from the literature, this article aims to (1) describe changes in the concept of adherence, drawing from the mental health treatment literature, (2) present a more comprehensive definition of adherence that recognizes the role of patient-provider transactions, (3) introduce dynamic adherence, a six-phase model, which incorporates the role of transactional processes and other factors that influence patients' adherence decisions, and (4) provide recommendations for providers to improve adherence as well as their relationships with patients. PMID:21790266

  10. Dynamic measurement of inside strain distributions in adhesively bonded joints by embedded fiber Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Murayama, Hideaki; Ning, Xiaoguang; Kageyama, Kazuro; Wada, Daichi; Igawa, Hirotaka

    2014-05-01

    Long-length fiber Bragg grating (FBG) with the length of about 100 mm was embedded onto the surface of a carbon fiber reinforced plastics (CFRP) substrate and two CFRP adherends were joined by adhesive to form an adhesive bonded single-lap joint. The joint was subjected to 0.5 Hz cyclic tensile load and longitudinal strain distributions along FBG were measured at 5 Hz by the fiber-optic distributed sensing system based on optical frequency domain reflectometry (OFDR). We could successfully monitor the strain distributions accurately with high spatial resolution of around 1 mm.

  11. Materials Adherence Experiment: Technology

    SciTech Connect

    Jenkins, P.P.; Landis, G.A.; Oberle, L.G.

    1997-12-31

    NASA`s Mars Pathfinder mission, launched December 4, 1996, reflects a new philosophy of exploiting new technologies to reduce mission cost and accelerate the pace of space exploration. Pathfinder will demonstrate a variety of new technologies aimed at reducing the cost of Mars exploration. Chief among these will be the demonstration of a solar-powered spacecraft on the surface of Mars. The Materials Adherence Experiment on Pathfinder was designed to measure the degradation of solar arrays due to dust settling out of the atmosphere and blocking light to the solar array, lowering the array power output.

  12. Comparison of FBG responses to static and dynamic pressures

    NASA Astrophysics Data System (ADS)

    Shafir, E.; Zilberman, S.; Ravid, A.; Glam, B.; Appelbaum, G.; Fedotov Gefen, A.; Saadi, Y.; Shafir, N.; Berkovic, G.

    2014-05-01

    FBGs respond to external pressures in ways that reflect both the strain-optic effect and the geometrical variations, both induced by the applied pressure. While the response to static isotropic pressure is quite straight forward and intuitive, the response to anisotropic shock waves is much more complex and depends also on the relative orientation between the fiber and the shock propagation direction. We describe and explain experimental results for both cases.

  13. Effect of residual strain on sensing property of FRP-OFBG smart rebar

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    FRP-OFBG smart rebar is the smart structure material, which is the integration of good mechanical property and sensing performance. And FRP-OFBG rebar can be widely used in civil engineering health monitoring. But in the smart rebar application procedure, there is large residual strain exiting in FBG in smart rebar, and multiple-peaked to FBG reflection spectrum, which affect the sensing performance of smart rebar. In this paper, it's theoretically analyzed using FBG to measure the residual strain in FRP after fabrication; In smart rebar pultrusion fabrication processing, the strain and temperature were monitored by two connecting FBGs. It's analyzed FRP fabrication processing through monitoring data; To the multiple-peaked smart rebar, which caused by nonuniform residual strain distributing along FBG length, post thermal treatment was done. The result proved that thermal treatment can improve the spectrum of smart rebar and remove the multiple-peaked phenomenon of smart rebar. But the thermal treatment can't relief the residual strain, and further research about how long will the residual strain recovery at room temperature must be done.

  14. Effects of molecular weight of dextran on the adherence of Streptococcus sanguis to damaged heart valves.

    PubMed Central

    Ramirez-Ronda, C H

    1980-01-01

    Dextran-producing streptococci such as Streptococcus sanguis are the organisms most frequently associated with infective endocarditis in humans. A series of experiments was designed to study how the molecular weight of dextrans affects the adherence of an endocarditis strain of S. sanguis to canine heart valves covered with platelets and fibrin. The data indicated that this adherence was dependent on dextrans of high molecular weight, such as dextran T-2000 or glucans isolated from S. sanguis or S. mutans. The adherence properties of the strain studied were not modified by prior exposure of the bacterial cells of valve leaflets to high-molecular-weight dextrans. Preexposure of bacterial cells or valve leaflets to low-molecular-weight dextrans decreased their adherence. Low-molecular-weight dextrans interfered with adherence of dextran-positive strains to damaged heart valves. PMID:6156909

  15. A hybrid Raman/EFPI/FBG sensing system for distributed temperature and key-point pressure measurements

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Zhou, Xinlei; Yang, Yang; Yu, Qingxu

    2015-08-01

    We demonstrate a hybrid sensing scheme, combining the incoherent optical frequency domain reflectometry (IOFDR) based Raman distributed temperature sensor (DTS) with the extrinsic Fabry-Perot interferometer (EFPI) based pressure sensor, for down-hole monitoring. The pressure measurement is compensated by a fiber Bragg grating (FBG) based temperature sensor. By using a laser diode as the common light source, a hybrid Raman/EFPI/FBG sensing system has been developed with a single fiber. The stimulated emission light and the spontaneous emission light of the laser diode are used for DTS and EFPI-FBG interrogations respectively. There can be no overlap between the spectral range of the Raman backscattered light and the spectral range of the reflected light from the EFPI-FBG sensor. Distributed temperature and pressure can thus be measured by using wavelength-division multiplexing (WDM) technology. Experimental results show that, both the distributed temperature and the key-point pressure can be measured alternatively with little interference.

  16. [Adherence to psychopharmacological treatment: Psychotherapeutic strategies to enhance adherence].

    PubMed

    Lencer, R; Korn, D

    2015-05-01

    Effective psychopharmacological medication with good tolerability represents the cornerstone of treatment for severe mental illness; however, the 1-year adherence rates are only approximately 50%. The term adherence emphasizes the collaborative responsibility of the clinician and the patient for a positive treatment outcome. Reasons for non-adherence are manifold and include patient-specific factors, such as self-stigmatization, lack of social and familial support, cognitive impairment and substance use besides insufficient effectiveness and the occurrence of side effects of the psychotropic drugs. To enhance adherence, both clinician and patient have to fully understand all the reasons for and against adherence to medication before a collaborative decision is made on future long-term treatment. A positive attitude towards medication critically depends on whether patients feel that the medication supports the attainment of the individual goals. PMID:25903501

  17. Design and development of a low power, low cost, portable fiber Bragg grating (FBG) sensor interrogation system

    NASA Astrophysics Data System (ADS)

    Cai, Zhaohui; Phua, Jiliang; Hao, Jianzhong; Dong, Bo; Wang, Xian; Meng, Yu Song; Chiam, Tat Meng

    2012-01-01

    In this paper, the design and development of a low power, low cost and portable FBG Interrogation System is presented. The FBG interrogator consists of a spectral analyzer module, a photo detection module, and an electronic processing module. By using volume holographic phase grating as the continuous dispersion spectral element, our interrogator can achieve a maximum scanning frequency as high as 5 KHz for a single channel with a total power requirement of 25 W.

  18. Design and development of a low power, low cost, portable fiber Bragg grating (FBG) sensor interrogation system

    NASA Astrophysics Data System (ADS)

    Cai, Zhaohui; Phua, Jiliang; Hao, Jianzhong; Dong, Bo; Wang, Xian; Meng, Yu Song; Chiam, Tat Meng

    2011-11-01

    In this paper, the design and development of a low power, low cost and portable FBG Interrogation System is presented. The FBG interrogator consists of a spectral analyzer module, a photo detection module, and an electronic processing module. By using volume holographic phase grating as the continuous dispersion spectral element, our interrogator can achieve a maximum scanning frequency as high as 5 KHz for a single channel with a total power requirement of 25 W.

  19. 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

  20. Initial adherence of EPEC, EHEC and VTEC to host cells

    PubMed Central

    Bardiau, Marjorie; Szalo, Mihai; Mainil, Jacques G.

    2010-01-01

    Initial adherence to host cells is the first step of the infection of enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic Escherichia coli (EHEC) and verotoxigenic Escherichia coli (VTEC) strains. The importance of this step in the infection resides in the fact that (1) adherence is the first contact between bacteria and intestinal cells without which the other steps cannot occur and (2) adherence is the basis of host specificity for a lot of pathogens. This review describes the initial adhesins of the EPEC, EHEC and VTEC strains. During the last few years, several new adhesins and putative colonisation factors have been described, especially in EHEC strains. Only a few adhesins (BfpA, AF/R1, AF/R2, Ral, F18 adhesins) appear to be host and pathotype specific. The others are found in more than one species and/or pathotype (EPEC, EHEC, VTEC). Initial adherence of EPEC, EHEC and VTEC strains to host cells is probably mediated by multiple mechanisms. PMID:20423697

  1. High-speed MEMS swept-wavelength light source for FBG sensor system

    NASA Astrophysics Data System (ADS)

    Saitoh, Takanori; Nakamura, Kenichi; Takahashi, Yoshifumi; Miyagi, Koichiro

    2005-05-01

    A high-speed MEMS swept-wavelength light source (SLS) for an FBG sensor system is proposed and demonstrated. It is basically a multi-mode external-cavity laser diode (LD), and consists mainly of an LD head, diffraction grating, and electromagnetically actuated MEMS scanning mirror. It has a linewidth of 0.03 nm, scan range from 1508 to 1582 nm, scan rate of 0.57 ms and output power of 10 mW. The heart of the MEMS SLS is the MEMS scanning mirror (8 x 6 mm) that changes the oscillation wavelength continuously and rapidly. The scanning mirror is actuated by electromagnetic force derived from a permalloy piece glued on the back of the mirror and a C-shape electromagnet. The MEMS SLS allows construction of a low-cost, simple and high-speed FBG interrogator system.

  2. Cable television monitoring system based on fiber laser and FBG sensor

    NASA Astrophysics Data System (ADS)

    Peng, Peng-Chun; Huang, Jun-Han; Wu, Shin-Shian; Yang, Wei-Yuan; Shen, Po-Tso

    2015-05-01

    We propose and experimentally demonstrate a cable television monitoring system based on a linear-cavity fiber laser and fiber Bragg grating (FBG) sensors. The linear-cavity fiber laser comprises a hybrid amplifier with an erbium-doped fiber amplifier and a semiconductor optical amplifier, a fiber loop mirror with a polarization controller and an optical coupler as a cavity mirror, and the FBG sensors acting as another cavity mirrors. Experimental results showed the feasibility of the monitoring system with sufficient of signal-to-noise ratio over 30 dB and stable output power, and the link of cable television signals on fiber link can monitored in real time. Excellent performances of carrier-to-noise ratio after long-distance transmission are obtained for cable television applications.

  3. Composite plate low energy impact localization system based on FBG sensing network and hybrid algorithm

    NASA Astrophysics Data System (ADS)

    Sai, Yaozhang; Jiang, Mingshun; Sui, Qingmei; Lu, Shizeng; Jia, Lei

    2015-08-01

    This paper proposed an impact localization system using fiber Bragg grating (FBG) network which is based on quasi-Newton algorithm and particle swarm optimization (PSO) algorithm. The FBG sensing network, formed by eight FBGs, was used to detect impact signals. And Shannon wavelet transform was employed to extract time differences. According to time differences and the coordinates of FBGs, nonlinear equations model of impact localization was established. Based on quasi-Newton algorithm and PSO algorithm, the nonlinear equations can be solved to obtain the coordinate of impact source. Testing experiments were carried out on a composite plate within 400 mm × 400 mm monitoring area. The experimental results showed that the maximum and average errors are 3.2 mm and 1.73 mm, respectively. The computational time is less than 2 s.

  4. 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.

  5. Surface deformation monitoring and reconstruction of honeycomb structure based on FBG sensors

    NASA Astrophysics Data System (ADS)

    Liu, Shulin; Lu, Jiyun; Zheng, Zhaoyu

    2015-07-01

    Honeycomb structure with high stiffness and light weight is expected to be more applied in the field of morphing wing. We propose a surface reconstruction algorithm based on FBG sensors to reconstruct the surface deformation of honeycomb structure real-timely and rapidly. When flexible honeycomb cores are driven by SMA actuators, the surface curvature monitored by FBG sensing array can be inferred from the changes of central wavelength. According to the surface reconstruction algorithm we proposed, the surface shape can be reconstructed. Composite single-row honeycomb structure specimen consisting of 8 cores, whose cell walls length and thickness is 8mm and 2mm respectively, is bended by electrified SMA actuators into the new steady shape. The experiment shows that the reconstructed surface shape has great agreement with the visual recording surface shape and the error is 5.76% on average.

  6. A non-contact FBG vibration sensor with double differential temperature compensation

    NASA Astrophysics Data System (ADS)

    Li, Tianliang; Tan, Yuegang; Zhou, Zude; Zheng, Kai

    2016-02-01

    This paper has presented a non-contact fiber Bragg grating (FBG) vibration sensor with double differential temperature compensation. Two FBGs and two states of the sensor have been employed to achieve double differential temperature compensation. Based on magnetic coupling and FBG sensing principle, it can be used to realize non-contact measurement of vibration of the rotating shaft. Experimental results show that the working band ranges are within 0-150 Hz; the sensitivity is -0.67 pm/µm, and the linearity is 3.87 % within a range of 2-2.6 mm. The fitting equation of temperature compensation which is caused by structural inflation can be expressed as: Δ λ 1' - Δ λ 2' = 1.51 × T - 32.97. When used to amend a temperature error, the sensor's temperature error will be reduced to 1.19 % in the range of 25-60 °C.

  7. Improvement of FBG peak wavelength demodulation using digital signal processing algorithms

    NASA Astrophysics Data System (ADS)

    Harasim, Damian; Gulbahar, Yussupova

    2015-09-01

    Spectrum reflected or transmitted by fiber Bragg grating (FBG) in laboratory environment usually has smooth shape with high signal to noise ratio, similar to Gaussian curve. However, in some applications reflected spectrum could included some strong noise, especially where sensing array contains large number of FBGs or while is used broadband, low power source. This paper presents a possibility for extraction fiber Bragg grating peak wavelength from spectra with weak signal to noise radio with most frequently using digital signal processing algorithms. The accuracy of function minimum, centroid and Gaussian fitting methods for peak wavelength detection is compared. The linearity of processing characteristics of extended FBG measured for reference high power and second, low power source is shown and compared.

  8. Single-frequency Yb-doped fiber laser with distributed feedback based on a random FBG

    NASA Astrophysics Data System (ADS)

    Abdullina, S. R.; Vlasov, A. A.; Lobach, I. A.; Belai, O. V.; Shapiro, D. A.; Babin, S. A.

    2016-07-01

    Single-frequency operation of a 1.03 μm fiber laser with random distributed feedback (RDFB) is demonstrated. The laser cavity is based on a 4 cm long fiber Bragg grating (FBG) consisting of 10 homogeneous subgratings with random phase and amplitude of refractive index modulation inscribed in a polarization maintaining (PM) Yb-doped fiber. Such RDFB laser generates single longitudinal mode with output power up to 25 mW, which is 3.5 times higher than that for a DFB laser based on regular π-shifted FBG of the same length in the same fiber. The single-frequency linewidth is measured to be  <100 kHz in both cases. The observed difference of the DFB and RDFB lasers is confirmed by numerical simulation showing different longitudinal distribution of intra-cavity radiation in these cases, analogous to those in the experiment.

  9. 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.

  10. Acoustic emission location on aluminum alloy structure by using FBG sensors and PSO method

    NASA Astrophysics Data System (ADS)

    Lu, Shizeng; Jiang, Mingshun; Sui, Qingmei; Dong, Huijun; Sai, Yaozhang; Jia, Lei

    2016-04-01

    Acoustic emission location is important for finding the structural crack and ensuring the structural safety. In this paper, an acoustic emission location method by using fiber Bragg grating (FBG) sensors and particle swarm optimization (PSO) algorithm were investigated. Four FBG sensors were used to form a sensing network to detect the acoustic emission signals. According to the signals, the quadrilateral array location equations were established. By analyzing the acoustic emission signal propagation characteristics, the solution of location equations was converted to an optimization problem. Thus, acoustic emission location can be achieved by using an improved PSO algorithm, which was realized by using the information fusion of multiple standards PSO, to solve the optimization problem. Finally, acoustic emission location system was established and verified on an aluminum alloy plate. The experimental results showed that the average location error was 0.010 m. This paper provided a reliable method for aluminum alloy structural acoustic emission location.

  11. Optical fiber relative humidity sensor based on FBG incorporated thin-core fiber modal interferometer.

    PubMed

    Gu, Bobo; Yin, Mingjie; Zhang, A Ping; Qian, Jinwen; He, Sailing

    2011-02-28

    A new fiber-optic relative humidity (RH) sensor based on a thin-core fiber modal interferometer (TCFMI) with a fiber Bragg grating (FBG) in between is presented. Poly (N-ethyl-4-vinylpyridinium chloride) (P4VP·HCl) and poly (vinylsulfonic acid, sodium salt) (PVS) are layer-by-layer deposited on the side surface of the sensor for RH sensing. The fabrication of the sensing nanocoating is characterized by using UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and scanning electron microscopy (SEM). The incorporation of FBG in the middle of TCFMI can compensate the cross sensitivity of the sensor to temperature. The proposed sensor can detect the RH with resolution of 0.78% in a large RH range at different temperatures. A linear, fast and reversible response has been experimentally demonstrated. PMID:21369243

  12. Multi FBG femtosecond laser inscription in FPI based pressure sensors for temperature distribution

    NASA Astrophysics Data System (ADS)

    Poeggel, Sven; Duraibabu, Dinesbabu; Lacraz, Amedee; Kalli, Kyriacos; Tosi, Daniele; Leen, Gabriel; Lewis, Elfed

    2015-09-01

    We present in this paper an optical fiber pressure and temperature sensor (OFPTS) with multi Fibre Bragg Grating (FBG) array. The sensor based on an extrinsic Fabry Perot interferometer and is fabricated from silica glass. A femtosecond laser (FSL) was used to inscribe multiple FBGs proximately close to the diaphragm, parallel to each other. This concepts allows a chain of FBGs with miniature active length which can be a significant important tool for medical application, like radio frequency ablation (RFA) cancer treatment.

  13. FBG feedback's effects on distributed Bragg reflector fiber laser's polarization modes' beat

    NASA Astrophysics Data System (ADS)

    Li, Yunbo; Yu, Kuanglu; Lao, Yiqin; Cheng, Linghao; Wu, Chongqing; Zhao, Yao; Shang, Chao

    2015-09-01

    Distributed Bragg reflector (DBR) fiber optic laser has recently been extensively explored as a powerful sensor for various measurands, thanks to its high sensitivity, excellent signal-to-noise ratio, and inherent electronic magnetic immunity. The phase noise and linewidth of the laser's beat note limits this sensor's performances. We report in this letter, our recent experiments on noise reduction employing optical feedback from an external FBG. We also investigated the sensitivity reduction of the DBR sensor after feedback is introduced.

  14. Aircraft health and usage monitoring system for in-flight strain measurement of a wing structure

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Hyuk; Park, Yurim; Kim, Yoon-Young; Shrestha, Pratik; Kim, Chun-Gon

    2015-10-01

    This paper presents an aircraft health and usage monitoring system (HUMS) using fiber Bragg grating (FBG) sensors. This study aims to implement and evaluate the HUMS for in-flight strain monitoring of aircraft structures. An optical-fiber-based HUMS was developed and applied to an ultralight aircraft that has a rectangular wing shape with a strut-braced configuration. FBG sensor arrays were embedded into the wing structure during the manufacturing process for effective sensor implementation. Ground and flight tests were conducted to verify the integrity and availability of the installed FBG sensors and HUMS devices. A total of 74 flight tests were conducted using the HUMS implemented testbed aircraft, considering various maneuvers and abnormal conditions. The flight test results revealed that the FBG-based HUMS was successfully implemented on the testbed aircraft and operated normally under the actual flight test environments as well as providing reliable in-flight strain data from the FBG sensors over a long period of time.

  15. Improved adherence with contingency management.

    PubMed

    Rosen, Marc I; Dieckhaus, Kevin; McMahon, Thomas J; Valdes, Barbara; Petry, Nancy M; Cramer, Joyce; Rounsaville, Bruce

    2007-01-01

    Contingency management (CM) based interventions that reinforce adherence to prescribed medications have shown promise in a variety of disadvantaged populations. Fifty-six participants with histories of illicit substance use who were prescribed antiretroviral medication but evidenced suboptimal adherence during a baseline assessment were randomly assigned to 16 weeks of weekly CM-based counseling or supportive counseling, followed by 16 additional weeks of data collection and adherence feedback to providers. The CM intervention involved review of data generated by electronic pill-bottle caps that record bottle opening (MEMS) and brief substance abuse counseling. CM participants were reinforced for MEMS-measured adherence with drawings from a bowl for prizes and bonus drawings for consecutive weeks of perfect adherence. Potential total earnings averaged $800. Mean MEMS-measured adherence to the reinforced medication increased from 61% at baseline to 76% during the 16-week treatment phase and was significantly increased relative to the supportive counseling group (p = 0.01). Furthermore, mean log-transformed viral load was significantly lower in the CM group. However, by the end of the 16-week follow-up phase, differences between groups in adherence and viral load were no longer significantly different. Proportions of positive urine toxicology tests did not differ significantly between the two groups at any phase. A brief CM-based intervention was associated with significantly higher adherence and lower viral loads. Future studies should evaluate methods to extend effects for longer term benefits. PMID:17263651

  16. Optimizing adherence to antiretroviral therapy

    PubMed Central

    Sahay, Seema; Reddy, K. Srikanth; Dhayarkar, Sampada

    2011-01-01

    HIV has now become a manageable chronic disease. However, the treatment outcomes may get hampered by suboptimal adherence to ART. Adherence optimization is a concrete reality in the wake of ‘universal access’ and it is imperative to learn lessons from various studies and programmes. This review examines current literature on ART scale up, treatment outcomes of the large scale programmes and the role of adherence therein. Social, behavioural, biological and programme related factors arise in the context of ART adherence optimization. While emphasis is laid on adherence, retention of patients under the care umbrella emerges as a major challenge. An in-depth understanding of patients’ health seeking behaviour and health care delivery system may be useful in improving adherence and retention of patients in care continuum and programme. A theoretical framework to address the barriers and facilitators has been articulated to identify problematic areas in order to intervene with specific strategies. Empirically tested objective adherence measurement tools and approaches to assess adherence in clinical/ programme settings are required. Strengthening of ART programmes would include appropriate policies for manpower and task sharing, integrating traditional health sector, innovations in counselling and community support. Implications for the use of theoretical model to guide research, clinical practice, community involvement and policy as part of a human rights approach to HIV disease is suggested. PMID:22310817

  17. [Treatment adherence: a key element].

    PubMed

    Bastida, Guillermo; Sánchez Montes, Cristina; Aguas, Mariam

    2011-12-01

    A substantial percentage of patients fail to follow health professionals' recommendations, which affects the management of chronic diseases, reducing the effectiveness of therapeutic interventions and increasing the costs of the disease. Lack of adherence is a multidimensional phenomenon and is influenced by numerous factors that should be identified. A multiplicity of measures is available to improve adherence, such as simplifying treatment administration, but none of these measures is effective when used alone. One way of tackling lack of adherence is by identifying patients' barriers to medication and involving them in decision making. Ulcerative colitis (UC) poses a risk for lack of treatment adherence. In this disease, poor adherence correlates with poor disease control (drug effectiveness) and with higher costs. As in other chronic diseases, the causes associated with poor adherence are multiple, including psychosocial factors, the physician-patient relationship and patients' prejudices toward medication. A single dose of aminosalycylates (5-ASA) should be recommended, as this dose is as safe and effective as other regimens. However, by itself, this recommendation does not seem to improve adherence. Identifying the scale of the problem and developing strategies to involve the patient in decision making is crucial to improve treatment adherence. PMID:25443221

  18. Antidepressant adherence after psychiatric hospitalization

    PubMed Central

    Zivin, Kara; Ganoczy, Dara; Pfeiffer, Paul N.; Miller, Erin M.; Valenstein, Marcia

    2010-01-01

    Objective Depressed patients discharged from psychiatric hospitalizations face increased risks for adverse outcomes including suicide, yet antidepressant adherence rates during this high-risk period are unknown. Using Veterans Affairs (VA) data, we assessed antidepressant adherence and predictors of poor adherence among depressed veterans following psychiatric hospitalization. Method We identified VA patients nationwide with depressive disorders who had a psychiatric hospitalization between April 1, 1999 and September 30, 2003, received antidepressant medication, and had an outpatient appointment following discharge. We calculated medication possession ratios (MPRs), a measure of medication adherence, within three and six months following discharge. We assessed patient factors associated with having lower levels of adherence (MPRs <0.8) after discharge. Results 20,931 and 23,182 patients met criteria for three and six month MPRs. The mean three month MPR was 0.79 (s.d.=0.37). The mean six month MPR was 0.66 (s.d.=0.40). Patients with poorer adherence were male, younger, non-white, and had a substance abuse disorder, but were less likely to have PTSD or other anxiety disorders. Conclusion Poor antidepressant adherence is common among depressed patients after psychiatric hospitalization. Efforts to improve adherence at this time may be critical in improving the outcomes of these high-risk patients. PMID:19609666

  19. Biologic Influences on Exercise Adherence.

    ERIC Educational Resources Information Center

    Dishman, Rod K.

    1981-01-01

    Diagnostic profiles of 362 male participants in an exercise program were analyzed to determine the biological variables between exercise adherence and symptoms of coronary disease. Findings indicated that individuals with lower metabolic capacity tended to adhere longer, to be less fit, were leaner, and began with more symptoms related to coronary…

  20. Packaging and testing of fiber Bragg gratings for use as strain sensor in rock specimens

    NASA Astrophysics Data System (ADS)

    Castro-Caicedo, Alvaro; Torres, Pedro; Lain, Ricardo

    2013-11-01

    This paper reports a packaging and calibration procedure for surface mounting of fiber Bragg grating (FBG) sensors to measure strain in rocks. The packaging of FBG sensors is performed with glass fiber and polyester resin, and then subjected to tensile loads in order to obtain strength and deformability parameters, necessaries to assess the mechanical performance of the sensor packaging. For a specific package, an optimal curing condition has been found, showing good repeatability and adaptability for non-planar surfaces, such as occurs in rock engineering. The successfully packaged sensors and electrical strain gages were attached to standard rock specimens of gabbro. Longitudinal and transversal strains under compression loads were measured with both techniques, showing that response of FBG sensors is linear and reliable. An analytical model is used to characterize the influences of rock substrate and FBG packaging in strain transmission. As a result, we obtained a sensor packaging for non-planar and complex natural material under acceptable sensitivity suitable for very small strains as occurs in hard rocks.

  1. 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.

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

    PubMed

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

    2016-01-01

    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

  3. 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.

  4. In vivo experiments of laser thermotherapy on liver tissue with FBG temperature distribution sensor

    NASA Astrophysics Data System (ADS)

    Chen, Na; Chen, Shaofeng; Zhu, Hongfei; Liu, Shupeng; Chen, Zhenyi; Pang, Fufei; Wang, Tingyun

    2012-06-01

    In this paper, we report an in vivo experimental study of liver tissue during Laser Induced Interstitial Thermotherapy (LITT). Single FBG was used in the experiments to measure the temperature distribution profile of the bio tissue in real time. Ideally, the goal of LITT is to kill pathological tissue thoroughly and minimize its damage to surrounding healthy tissue, especially vital organs. The extent of treated tissue damage in the therapy is mainly dependent on the irradiation time and the laser power density at the tissue surface. Therefore, monitoring the dynamic change of the exact temperature distribution of the tissue is a key point for the safety of this treatment. In our experiments, FBG was embedded in the laser irradiated bio tissues and used as fully distributed temperature sensor. During the therapy, its reflection spectra were recorded and transmitted to PC in real time. The temperature profile along the FBG axial was reconstructed from its reflection spectrum by the spectra inversion program running on the PC. We studied the dependence of the temperature distribution and the laser output power experimentally and compared the results of in vivo and in vitro under similar laser irradiating conditions. Experimental results demonstrate the effectiveness of this method. Due to influence of body temperature, the in vivo measured temperature is higher than the in vitro one with an almost constant temperature difference value, but the slope and trend of the measured temperature curves in vivo and in vitro are almost identical.

  5. 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

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

    SciTech Connect

    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 magnetic 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.

  7. A Localized Adherence-Like Pattern as a Second Pattern of Adherence of Classic Enteropathogenic Escherichia coli to HEp-2 Cells That Is Associated with Infantile Diarrhea

    PubMed Central

    Scaletsky, Isabel C. A.; Pedroso, Margareth Z.; Oliva, Carlos A. G.; Carvalho, Rozane L. B.; Morais, Mauro B.; Fagundes-Neto, Ulysses

    1999-01-01

    Escherichia coli strains that cause nonbloody diarrhea in infants are known to present three distinct patterns of adherence to epithelial cells, namely, localized (LA), diffuse (DA), and aggregative (AA) adherence. Strains with LA (typical Enteropathogenic Escherichia coli [EPEC]) are well recognized as a cause of secretory diarrhea, but the role of strains with DA (DAEC) is controversial, and strains with AA (EAEC) have been more frequently related to persistent diarrhea whereas its relationship with acute diarrhea is not well defined. To determine the relationship of the different types of E. coli adherence patterns with acute diarrhea (lasting less than 14 days) and persistent diarrhea (lasting more than 14 days) in São Paulo, Brazil, we studied stool specimens from 40 infants under 1 year of age with diarrhea and 40 age-matched control infants without any gastrointestinal symptoms. Twenty-eight (35.0%) of eighty cases yielded adherent E. coli (HEp-2 cells). Strains with localized and aggregative adherence were associated with acute and persistent diarrhea. A total of 11.2% of the adherent strains were typical EPEC serotypes and hybridized with the enteroadherence factor probe; 5.0% were EAEC and hybridized with the EAEC probe. DAEC strains were isolated from 10.0% of patients and 7.5% of controls and did not hybridize with the two probes used (daaC and AIDA-I). Strains with a localized adherence-like pattern (atypical EPEC) were found significantly more frequently (P = 0.028) in cultures from children with diarrhea (17.5%) than in controls (2.5%). PMID:10377120

  8. Effect of plastic catheter material on bacterial adherence and viability.

    PubMed

    Lopez-Lopez, G; Pascual, A; Perea, E J

    1991-06-01

    The kinetics of adherence of single isolates of Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa and Escherichia coli to catheters made of polyvinyl chloride (PVC), Teflon, siliconised latex, polyurethane and Vialon was evaluated by a radiometric assay. Radiolabelled bacteria (10(8) cfu/ml) were incubated in vials containing 1-cm lengths of catheter for up to 3 days. The peak of maximal adherence to each biomaterial was reached after 24 h for P. aeruginosa and after 72 h for the other strains. Bacterial adherence to PVC and siliconised latex was significantly higher (2-6 times; p less than 0.05) than to the other biomaterials for all the strains. The lowest values of adherence were observed with polyurethane and Vialon for the staphylococci but with Teflon for E. coli and P. aeruginosa. Bacterial viability and growth was evaluated in eluates obtained from incubation of segments of each catheter in buffer for 24 h. None of the eluates affected the viability of the staphylococci. However, all of them, significantly increased the growth of E. coli and P. aeruginosa with the exception of the eluate from siliconised latex, in which the inoculum count was reduced to an undetectable level for E. coli. We conclude that bacterial adherence to catheters may depend in part on the nature of the biomaterial and that certain substances eluted from the catheters may affect the viability and growth of different micro-organisms. PMID:1905357

  9. Adherence of oral streptococci to an immobilized antimicrobial agent.

    PubMed

    Saito, T; Takatsuka, T; Kato, T; Ishihara, K; Okuda, K

    1997-08-01

    An antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was immobilized on silica. Interaction between the material (termed) OAIS) and various oral bacterial species were then studied. Seven species of Streptococcus and two Actinomyces were investigated for their ability to adhere to this biomaterial. Cell-surface hydrophobicity and zeta-potential were examined as well. Analysis of extracted hydrophobic proteins which adhered to OAIS revealed that the adherence of these micro-organisms was closely related to the hydrophobicity of their cell surfaces. The results of zeta-potential assays indicated that negative charge on the cell surface inhibited adherence to OAIS. Gel electrophoresis revealed that OAIS could absorb cell-surface hydrophobic proteins from all bacterial species tested. Preadsorption of hydrophobic components on the cell surface inhibited adherence of the Strep. mutans strain to OAIS in a dose-dependent manner. The results indicate that OAIS adsorption of these oral bacteria was dependent on the degree of hydrophobicity of their surfaces. A major component of this adherence was hydrophobic cell-surface proteins. PMID:9347116

  10. Decreased Adherence of Enterohemorrhagic Escherichia coli to HEp-2 Cells in the Presence of Antibodies That Recognize the C-Terminal Region of Intimin

    PubMed Central

    Gansheroff, Lisa J.; Wachtel, Marian R.; O'Brien, Alison D.

    1999-01-01

    Antiserum raised against intimin from enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain 86-24 has been shown previously by our laboratory to inhibit adherence of this strain to HEp-2 cells. In the present study, we sought to identify the region(s) of intimin important for the effect of anti-intimin antisera on EHEC adherence and to determine whether antisera raised against intimin from an O157:H7 strain could reduce adherence of other strains. Compared to preimmune serum controls, polyclonal sera raised against the histidine-tagged intimin protein RIHisEae (intiminO157) or against His-tagged C-terminal fragments of intimin from strain 86-24 reduced adherence of this strain. Furthermore, an antibody fraction purified from the anti-RIHisEae serum that contained antibodies to the C-terminal third of intimin, the putative receptor-binding domain, also reduced adherence of strain 86-24, but a purified fraction containing antibodies to the N-terminal two-thirds of intimin did not inhibit adherence. The polyclonal anti-intiminO157 serum raised against RIHisEae inhibited, to different degrees, the adherence of another O157:H7 strain, an EHEC O55:H7 strain, one of two independent EHEC O111:NM isolates tested, and one of two EHEC O26:H11 strains tested. Adherence of the other O26:H11 and O111:NM strains and an EPEC O127:H6 strain was not reduced. Finally, immunoblot analysis indicated a correlation between the antigenic divergence in the C-terminal third of intimins from different strains and the capacity of anti-intiminO157 antiserum to reduce adherence of heterologous strains. Taken together, these data suggest that intiminO157 could be used as an immunogen to elicit adherence-blocking antibodies against O157:H7 strains and closely-related EHEC. PMID:10569757

  11. Clustering based on adherence data

    PubMed Central

    2011-01-01

    Adherence to a medical treatment means the extent to which a patient follows the instructions or recommendations by health professionals. There are direct and indirect ways to measure adherence which have been used for clinical management and research. Typically adherence measures are monitored over a long follow-up or treatment period, and some measurements may be missing due to death or other reasons. A natural question then is how to describe adherence behavior over the whole period in a simple way. In the literature, measurements over a period are usually combined just by using averages like percentages of compliant days or percentages of doses taken. In the paper we adapt an approach where patient adherence measures are seen as a stochastic process. Repeated measures are then analyzed as a Markov chain with finite number of states rather than as independent and identically distributed observations, and the transition probabilities between the states are assumed to fully describe the behavior of a patient. The patients can then be clustered or classified using their estimated transition probabilities. These natural clusters can be used to describe the adherence of the patients, to find predictors for adherence, and to predict the future events. The new approach is illustrated and shown to be useful with a simple analysis of a data set from the DART (Development of AntiRetroviral Therapy in Africa) trial in Uganda and Zimbabwe. PMID:21385451

  12. A Strain-Based Load Identification Model for Beams in Building Structures

    PubMed Central

    Hong, Kappyo; Lee, Jihoon; Choi, Se Woon; Kim, Yousok; Park, Hyo Seon

    2013-01-01

    A strain-based load identification model for beam structures subjected to multiple loads is presented. The number of sensors for the load identification model is the same as the number of load conditions acting on a beam structure. In the model, the contribution of each load to the strains measured by strain sensors is defined. In this paper, the longitudinal strains measured from multiplexed fiber Bragg grating (FBG) strain sensors are used in the load identification. To avoid the dependency on the selection of locations for FBG sensors installed on a beam structure, the measured strain is expressed by a general form of a strain sensing model defined by superimposing the distribution shapes for strains from multiple loads. Numerical simulation is conducted to verify the model. Then, the load identification model is applied to monitoring of applied loads on a 4 m-long steel beam subjected to two concentrated loads. In the experiment, seven FBG sensors and nine electrical strain gages (ESGs) were installed on the surface of the bottom flange. The experimental results indicate a good agreement between estimated loadings from the model and the loads applied by a hydraulic jack. PMID:23921825

  13. Emerging Enteropathogenic Escherichia coli Strains?

    PubMed Central

    Irino, Kinue; Girão, Dennys M.; Girão, Valéria B.C.; Guth, Beatriz E.C.; Vaz, Tânia M.I.; Moreira, Fabiana C.; Chinarelli, Silvia H.; Vieira, Mônica A.M.

    2004-01-01

    Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic. PMID:15504277

  14. 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.

  15. The Mannose-Sensitive Hemagglutinin of Vibrio cholerae Promotes Adherence to Zooplankton

    PubMed Central

    Chiavelli, Deborah A.; Marsh, Jane W.; Taylor, Ronald K.

    2001-01-01

    The bacterium Vibrio cholerae, the etiological agent of cholera, is often found attached to plankton, a property that is thought to contribute to its environmental persistence in aquatic habitats. The V. cholerae O1 El Tor biotype and V. cholerae O139 strains produce a surface pilus termed the mannose-sensitive hemagglutinin (MSHA), whereas V. cholerae O1 classical biotype strains do not. Although V. cholerae O1 classical does not elaborate MSHA, the gene is present and expressed at a level comparable to that of the other strains. Since V. cholerae O1 El Tor and V. cholerae O139 have displaced V. cholerae O1 classical as the major epidemic strains over the last fifteen years, we investigated the potential role of MSHA in mediating adherence to plankton. We found that mutation of mshA in V. cholerae O1 El Tor significantly diminished, but did not eliminate, adherence to exoskeletons of the planktonic crustacean Daphnia pulex. The effect of the mutation was more pronounced for V. cholerae O139, essentially eliminating adherence. Adherence of the V. cholerae O1 classical mshA mutant was unaffected. The results suggest that MSHA is a factor contributing to the ability of V. cholerae to adhere to plankton. The results also showed that both biotypes of V. cholerae O1 utilize factors in addition to MSHA for zooplankton adherence. The expression of MSHA and these additional, yet to be defined, adherence factors differ in a serogroup- and biotype-specific manner. PMID:11425745

  16. Factors involved in adherence of lactobacilli to human Caco-2 cells.

    PubMed Central

    Greene, J D; Klaenhammer, T R

    1994-01-01

    A quantitative assay performed with bacterial cells labelled with [3H]thymidine was used to investigate factors involved in the adherence of human isolates Lactobacillus acidophilus BG2FO4 and NCFM/N2 and Lactobacillus gasseri ADH to human Caco-2 intestinal cells. For all three strains, adherence was concentration dependent, greater at acidic pH values, and significantly greater than adherence of a control dairy isolate, Lactobacillus delbrueckii subsp. bulgaricus 1489. Adherence of L. acidophilus BG2FO4 and NCFM/N2 was decreased by protease treatment of the bacterial cells, whereas adherence of L. gasseri ADH either was not affected or was enhanced by protease treatment. Putative surface layer proteins were identified on L. acidophilus BG2FO4 and NCFM/N2 cells but were not involved in adherence. Periodate oxidation of bacterial cell surface carbohydrates significantly reduced adherence of L. gasseri ADH, moderately reduced adherence of L. acidophilus BG2FO4, and had no effect on adherence of L. acidophilus NCFM/N2. These results indicate that Lactobacillus species adhere to human intestinal cells via mechanisms which involve different combinations of carbohydrate and protein factors on the bacterial cell surface. The involvement of a secreted bridging protein, which has been proposed as the primary mediator of adherence of L. acidophilus BG2FO4 in spent culture supernatant (M.-H. Coconnier, T. R. Klaenhammer, S. Kernéis, M.-F. Bernet, and A. L. Servin, Appl. Environ. Microbiol. 58:2034-2039, 1992), was not confirmed in this study. Rather, a pH effect on Caco-2 cells contributed significantly to the adherence of this strain in spent culture supernatant.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:7811085

  17. Medication Adherence Measures: An Overview

    PubMed Central

    Lam, Wai Yin; Fresco, Paula

    2015-01-01

    WHO reported that adherence among patients with chronic diseases averages only 50% in developed countries. This is recognized as a significant public health issue, since medication nonadherence leads to poor health outcomes and increased healthcare costs. Improving medication adherence is, therefore, crucial and revealed on many studies, suggesting interventions can improve medication adherence. One significant aspect of the strategies to improve medication adherence is to understand its magnitude. However, there is a lack of general guidance for researchers and healthcare professionals to choose the appropriate tools that can explore the extent of medication adherence and the reasons behind this problem in order to orchestrate subsequent interventions. This paper reviews both subjective and objective medication adherence measures, including direct measures, those involving secondary database analysis, electronic medication packaging (EMP) devices, pill count, and clinician assessments and self-report. Subjective measures generally provide explanations for patient's nonadherence whereas objective measures contribute to a more precise record of patient's medication-taking behavior. While choosing a suitable approach, researchers and healthcare professionals should balance the reliability and practicality, especially cost effectiveness, for their purpose. Meanwhile, because a perfect measure does not exist, a multimeasure approach seems to be the best solution currently. PMID:26539470

  18. Medication Adherence Measures: An Overview.

    PubMed

    Lam, Wai Yin; Fresco, Paula

    2015-01-01

    WHO reported that adherence among patients with chronic diseases averages only 50% in developed countries. This is recognized as a significant public health issue, since medication nonadherence leads to poor health outcomes and increased healthcare costs. Improving medication adherence is, therefore, crucial and revealed on many studies, suggesting interventions can improve medication adherence. One significant aspect of the strategies to improve medication adherence is to understand its magnitude. However, there is a lack of general guidance for researchers and healthcare professionals to choose the appropriate tools that can explore the extent of medication adherence and the reasons behind this problem in order to orchestrate subsequent interventions. This paper reviews both subjective and objective medication adherence measures, including direct measures, those involving secondary database analysis, electronic medication packaging (EMP) devices, pill count, and clinician assessments and self-report. Subjective measures generally provide explanations for patient's nonadherence whereas objective measures contribute to a more precise record of patient's medication-taking behavior. While choosing a suitable approach, researchers and healthcare professionals should balance the reliability and practicality, especially cost effectiveness, for their purpose. Meanwhile, because a perfect measure does not exist, a multimeasure approach seems to be the best solution currently. PMID:26539470

  19. Reversible Daptomycin Tolerance of Adherent Staphylococci in an Implant Infection Model ▿

    PubMed Central

    John, Anne-K.; Schmaler, Mathias; Khanna, Nina; Landmann, Regine

    2011-01-01

    Daptomycin (DAP) is bactericidal against methicillin-resistant Staphylococcus aureus (MRSA) in vitro, but it failed to eradicate MRSA in an experimental model of implant-associated infection. We therefore investigated various factors which could explain treatment failure by evaluating DAP activity, including the role of different cell wall components, adherence, biofilm, and calcium ions (Ca2+) in vitro and in vivo. In the tissue cage infection model, DAP was active only prophylactically and against low inocula. To identify the mechanisms of treatment failure, the in vitro activity of DAP against planktonic and adherent growing S. aureus and S. epidermidis mutants, differing in their capacity of biofilm formation and adherence, was determined. For planktonic staphylococci, the MIC was 0.625 μg/ml. For adherent staphylococci, DAP reduced biofilms at 30 μg/ml. However, it did not kill adherent bacteria up to 500 μg/ml, independent of biofilm biosynthesis (the ica mutant strain), nuclease (the nuc1/nuc2 mutant strain), LPXTG-anchored adhesin (the srtA mutant strain), autolysin (the atl mutant strain), or alanyl-LTA (the dltA mutant strain). Resistance of adherent staphylococci was not due to mutations of adherent bacteria, since staphylococci became DAP susceptible after detachment. Phenotypic tolerance was not explained by inactivation of DAP or inability of initial Ca2+-DAP complex formation. However, the addition of up to 100 mg/liter (2.5 mmol/liter) Ca2+ gradually improved bactericidal activity toward adherent staphylococci in vitro and increased the prevention rate in the cage model from 40% to 60%. In summary, adherent staphylococci are resistant to DAP killing unless Ca2+ is supplemented to physiologic concentrations. PMID:21576433

  20. 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. PMID:25361108

  1. 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

    2016-02-01

    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. PMID:26653438

  2. 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

  3. EX VIVO ADHERENCE TO MURINE ILEAL, BIOFILM FORMATION ABILITY AND PRESENCE OF ADHERENCE-ASSOCIATED OF HUMAN AND ANIMAL DIARRHEAGENIC ESCHERICHIA COLI.

    PubMed

    Sukkua, Kannika; Rattanachuay, Pattamarat; Sukhumungoon, Pharanai

    2016-01-01

    Diarrheagenic Escherichia coli (DEC) are important bacteria causing gastrointestinal infection, which can lead to severe forms of illnesses. This study focused on DEC adherent capabilities using murine intestinal tissue as a model. Ex vivo adherence results showed that enteroaggregative E. coli (EAEC) strain PSU280 exhibited the highest level of adherence, followed by strains from ETEC category. Scanning electron micrographs displayed tight binding and putative bacterial curli fibers, including putative fimbrial structures. The presence of putative curli fibers was confirmed by the presence of csgA, a curli major structural subunit gene. Five and 3 of 15 DEC possessed lpf (encoding long polar fimbriae) and agn43 (encoding antigen43), respectively. Comparable biofilm formation efficiency but variable levels autoaggregation were observed among the DEC strains. In addition, yeast agglutination could be visualized in 11/15 strains. This study demonstrates the adherent ability of DEC strains isolated in southern Thailand as well as a number of crucial adherence-associated genes, information of importance to the understanding of DEC pathogenesis in this region of the country. PMID:27086424

  4. Discretely tunable Tm-doped fiber-based MOPA using FBG arrays as spectral filters

    NASA Astrophysics Data System (ADS)

    Tiess, T.; Junaid, S.; Becker, M.; Rothhardt, M.; Bartelt, H.; Jäger, M.

    2016-03-01

    Over the past years, Thulium (Tm) -doped fiber lasers in the 2μm region have gained a lot of interest due to many potential applications in materials processing and biophotonics. Based on the broad gain regions spanning from 1800nm to 2100nm, they offer the perfect basis to implement broadly tunable and user-friendly light sources like they are increasingly demanded in spectroscopic applications. Recently, a novel tuning mechanism based on a fiber Bragg grating (FBG) array as versatile spectral filter has been reported. This concept combines unique spectral freedom for customized tuning ranges and ultrabroad bandwidths with a fiber-integrated setup in order to maintain the advantages of the waveguide geometry. In this work, we demonstrate such a dispersion tuned and pulsed fiber laser in the Tm domain around 1950nm using a modulator and a discrete FBG array to control the emission wavelength. In order to comply with the demands of potential applications in biophotonics, for the first time, this tuning concept is realized in a polarization maintaining (PM) configuration ensuring linearly polarized output. While a simple FBG array is employed containing five gratings inscribed in PM fiber, we also outline the prospect to implement FBGs fabricated in a standard single mode fiber. The emission characteristics of the system are investigated showing pulse durations down to 11ns and a good spectral signal contrast. In order to highlight the prospect for tunable high-power operation, we have also implemented an amplification stage scaling the average power to more than 25W.

  5. Linearized interrogation of FDML FBG sensor system using PMF Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Lee, Hwi Don; Jung, Eun Joo; Jeong, Myung Yung; Kim, Chang-Seok

    2009-10-01

    A novel linearized interrogation method is presented for Fourier-domain mode locked (FDML) fiber Bragg grating (FBG) sensor system. In the ultra high-speed regime over 10 kHz modulation, only sine wave is available to scan a center wavelength of FDML wavelength-swept laser instead of conventional triangular wave. However, sine wave modulation has been suffered an exaggerated nonlinear filter response in demodulating the time-encoded parameter into the absolute wavelength. The linearized demodulation is demonstrated by the third order polynomial conversion of filter between the time-encoded parameter and wavelength-encoded parameter based on the spectral information of polarization maintaining fiber (PMF) Sagnac interferometer.

  6. Two-function light source in a FBG multi-point sensing system

    NASA Astrophysics Data System (ADS)

    He, Shi-Ya; Deng, Yan-Hao; Yu, Yang; Hu, Shu-Yang; Guan, Zheng

    2007-05-01

    In this paper, a two-function light source is recommended. It can both amplify the light power and demodulate the wavelength signal. Its output power is 1000 times as high as traditional broadband light source (BBS) and it can demodulate the signal by scanning wavelength in 30 nm of bandwidth range in the situation of 1550 nm central wavelength. This kind of light source effectively solves the problem of light energy supply in more-point measurement of FBG and simplifies the structure of sensing measurement.

  7. Linear FBG interrogation with a wavelength-swept fiber laser and a volume phase grating spectrometer

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjin; Song, Minho

    2011-05-01

    We propose a novel FBG (fiber Bragg grating) sensor system that uses a tunable wavelength laser and a volume phase grating spectrometer. The effect of nonlinear wavelength scanning and uneven power profile of the fiber laser, which substantially degrades the measurement accuracy, is minimized by using a spectrometer demodulation. The constructed sensor system showed linear output according to the Bragg wavelength variation, and showed much higher signal-to-noise ratio compared to the conventional spectrometer demodulation which used much dimmer broadband light sources.

  8. The magnitude of a human bite measured exactly at the molar Intercuspidation using FBG

    NASA Astrophysics Data System (ADS)

    Marin, Gabriela Costa; Milczewski, Maura S.; Abe, Ilda; Lopes, Stephani C. P. S.; Camargo, Elisa S.; Kalinowski, Hypolito J.

    2014-05-01

    The aim of the study is to develop a new punctual method to determine the human bite force, between uppers and lowers first molars, at the moment of occlusion in maximum intercuspation. Fibre optic Bragg gratings are encapsulated in an acetate splint made by casting of a volunteer lower dentition. Splint sensor was positioned into the mouth to be pressured with minimal occlusal interference. The transversal pressure on the FBG was acquired at the moment of before occlusion (free), occlusion and biting. The measured forces were 12N during occlusion and 28N bite force, between right uppers and lowers first molars.

  9. Development and field trial of a FBG-based magnetic sensor for large hydrogenerators

    NASA Astrophysics Data System (ADS)

    Fracarolli, João. P. V.; Rosolem, João. B.; Tomiyama, Elias K.; Floridia, Claudio; Penze, Rivael S.; Peres, Rodrigo; Dini, Danilo C.; Hortencio, Claudio A.; Dilli, Paulo I. G.; da Silva, Erlon V.; dos Santos, Marcéu. C.; Fruett, Fabiano

    2016-05-01

    We propose a passive optical sensor for online magnetic field monitoring in large hydrogenerators, based on FBG (Fiber Bragg Grating) technology and a magnestostrictive material (Terfenol-D). The objective of this sensor is to detect faults in the rotor windings due to inter turn short-circuits. This device is packaged in a novel rod-shaped enclosure, allowing it to be easily installed on the ventilation ducts of the stator of the machine. This sensor was developed and tested in laboratory and it has been evaluated in a field test on a 200 MVA, 60 poles hydrogenerator.

  10. Interrogation of a cascaded FBG sensor using a wavelength-to-delay mapping technique

    NASA Astrophysics Data System (ADS)

    Clement, Juan; Hervás, Javier; Fernández-Pousa, Carlos R.; Barrera, David; Pastor, Daniel; Sales, Salvador; Capmany, José

    2015-09-01

    An optical fiber sensor composed of six standard FBGs in cascade is interrogated by use of a technique based on wavelength to delay mapping. A microwave-modulated optical signal enters the FBG cascade and, after being sliced and reflected, experiences dispersion in standard single-mode fiber. The Bragg wavelengths of the FBGs are mapped into the delays that determine the peaks in the system's electrical impulse response. The Bragg wavelength shifts are calculated from the difference of the delays undergone by FBGs samples. A resolution of 9.2 pm in Bragg wavelength shift is demonstrated.

  11. The effectiveness of metal coating on FBG sensor sensitivity at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Lupi, C.; Felli, F.; Caponero, M. A.; Paolozzi, A.

    2007-07-01

    The very low thermal expansion coefficient of silica at cryogenic temperature prevents the use of Fibre Bragg Grating (FBG) sensors for high resolution temperature monitoring in cryogenic environments involving liquid gases or space applications. To overcome such limitations sensors have been coated with different metals to improve the measurement sensitivity in the very low temperature region, i.e. 4.2-35 K. Various coatings have been deposited by electrowinning on the external fibre surface after aluminium pre-coating. Full characterization of this new type of sensor is described in the paper.

  12. 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.

  13. Active mechanics and geometry of adherent cells and cell colonies

    NASA Astrophysics Data System (ADS)

    Banerjee, Shiladitya

    2014-03-01

    Measurements of traction stresses exerted by adherent cells or cell colonies on elastic substrates have yielded new insight on how the mechanical and geometrical properties of the substrate regulate cellular force distribution, mechanical energy, spreading, morphology or stress ber architecture. We have developed a generic mechanical model of adherent cells as an active contractile gel mechanically coupled to an elastic substrate and to neighboring cells in a tissue. The contractile gel model accurately predicts the distribution of cellular and traction stresses as observed in single cell experiments, and captures the dependence of cell shape, traction stresses and stress ber polarization on the substrate's mechanical and geometrical properties. The model further predicts that the total strain energy of an adherent cell is solely regulated by its spread area, in agreement with recent experiments on micropatterned substrates with controlled geometry. When used to describe the behavior of colonies of adherent epithelial cells, the model demonstrates the crucial role of the mechanical cross-talk between intercellular and extracellular adhesion in regulating traction force distribution. Strong intercellular mechanical coupling organizes traction forces to the colony periphery, whereas weaker intercellular coupling leads to the build up of traction stresses at intercellular junctions. Furthermore, in agreement with experiments on large cohesive keratinocyte colonies, the model predicts a linear scaling of traction forces with the colony size. This scaling suggests the emergence of an effective surface tension as a scale-free material property of the adherent tissue, originating from actomyosin contractility.

  14. The challenge of patient adherence.

    PubMed

    Martin, Leslie R; Williams, Summer L; Haskard, Kelly B; Dimatteo, M Robin

    2005-09-01

    Quality healthcare outcomes depend upon patients' adherence to recommended treatment regimens. Patient nonadherence can be a pervasive threat to health and wellbeing and carry an appreciable economic burden as well. In some disease conditions, more than 40% of patients sustain significant risks by misunderstanding, forgetting, or ignoring healthcare advice. While no single intervention strategy can improve the adherence of all patients, decades of research studies agree that successful attempts to improve patient adherence depend upon a set of key factors. These include realistic assessment of patients' knowledge and understanding of the regimen, clear and effective communication between health professionals and their patients, and the nurturance of trust in the therapeutic relationship. Patients must be given the opportunity to tell the story of their unique illness experiences. Knowing the patient as a person allows the health professional to understand elements that are crucial to the patient's adherence: beliefs, attitudes, subjective norms, cultural context, social supports, and emotional health challenges, particularly depression. Physician-patient partnerships are essential when choosing amongst various therapeutic options to maximize adherence. Mutual collaboration fosters greater patient satisfaction, reduces the risks of nonadherence, and improves patients' healthcare outcomes. PMID:18360559

  15. Effect of tubing material on conventional and thin FBG sensor for embedded environment impact monitoring of CFRP composites

    NASA Astrophysics Data System (ADS)

    Park, Yurim; Shrestha, Pratik; Kwon, Hyunseok; Kim, Jin-Hyuk; Kwon, Heejung; Kim, Chun-Gon

    2016-04-01

    Applications of composite materials in aerospace structures is increasing due to the outstanding properties, however, monitoring such composite structures exposed to harsh environments is still a posing issue. Low Earth orbit space structures are exposed to property degradation and damage from high-degree vacuum, ultraviolet radiation, thermal cycling, and atomic oxygen attack which are detrimental to composite materials. In this study, FBG sensors for embedding in CFRP composite plates in different thickness locations to provide health and damage monitoring of the material exposed to such environments regarding the overall health of the material with a focus on the exposed surface are explored in comparison to conventional FBG sensors.

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

    PubMed Central

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

    1996-01-01

    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. PMID:8779562

  17. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    NASA Astrophysics Data System (ADS)

    Jülich, Florian; Aulbach, Laura; Wilfert, Andre; Kratzer, Peter; Kuttler, Rolf; Roths, Johannes

    2013-09-01

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches.

  18. Intracore fiber bragg gratings for strain measurement in embedded composite structures.

    PubMed

    Murukeshan, V M; Chan, P Y; Ong, L S; Asundi, A

    2001-01-01

    An intracore Bragg grating written on a photosensitive fiber core is used for strain measurement in composite specimens under load. The strain information is directly related to the absolute change in the Bragg-reflected wavelength. Fiber Bragg grating (FBG) sensors (fibers with intracore gratings) are thus sensitive to strain that is caused by changes in temperature as well as to load-induced changes. Thus these sensors can be made to be independent of source intensity variations and losses. FBG sensors used for load-induced strain sensing in composite structures and the effects of temperature on them are discussed. A detailed account of the use of such embedded structures as self-monitoring nondestructive testing devices is given. PMID:18356985

  19. 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.

  20. Debonding monitoring of a composite repair patch using small-diameter FBG sensors

    NASA Astrophysics Data System (ADS)

    Takeda, Shin-ichi; Yamamoto, Takeharu; Okabe, Yoji; Takeda, Nobuo

    2004-07-01

    This paper presents the health monitoring technique of composite repair patches using small-diameter fiber Bragg grating (FBG) sensors. The composite patch structures consist of carbon fiber reinforced plastic (CFRP) patches, aluminum substrates and adhesive layers. The debonding progressed between aluminum substrate and the adhesive layers under cyclic loading. In this research, two types of the specimen were prepared for evaluation of the debonding size. One is specimen with the patches glued on the both side of the aluminum plate. The other is pre-notched specimen for investigation of the influence of the crack propagation in the substrate. The FBG sensors were embedded into the adhesive layers easily, because the diameter of the sensor was only 52 μm. Reflection spectra from the sensor were measured at various lengths of the debonding. The form of the spectrum changed sensitively with an increase in the debonding size. For confirmation of the measured results, the spectra were simulated theoretically. As a result, the change in the calculated spectrum was consistent with that in the measured spectrum, and the relation between the spectrum and the debonding was clarified. Moreover, the debonding length was evaluated quantitatively by the monitoring of the form of the reflection spectrum.

  1. Linearization of an intensity-modulated analog photonic link using an FBG and a dispersive fiber

    NASA Astrophysics Data System (ADS)

    Gao, Yongsheng; Wen, Aijun; Chen, Yan; Zhang, Huixing; Xiang, Shuiying

    2015-03-01

    An optical linearization technique for an intensity-modulated analog photonic link is proposed and demonstrated. Conventional double-sideband intensity modulation is applied to modulate the radio frequency (RF) signal onto the optical carrier; then a fiber Bragg grating (FBG) is used to suppress part of the optical carrier and a single mode fiber (SMF) is followed to introduce some dispersion. By properly adjusting the dispersion-induced phase shift, the third-order intermodulation distortion can be suppressed. The proposed scheme is simple and low cost. The FBG can be also used to optimize the power ratio of the optical carrier and sidebands, thus improving the link gain, while the SMF can act as a transmission medium to deliver the RF signal. Experimental results show that an improvement of 12.6 dB in the spurious-free dynamic range and 3.8 dB in the link gain is achieved after linearization. The frequency tunability of the linearization technique is also evaluated by the transmission of RF signals with different center frequencies and bandwidths.

  2. Adherence and receptor relationships of Candida albicans.

    PubMed Central

    Calderone, R A; Braun, P C

    1991-01-01

    The cell surface of Candida albicans is composed of a variety of polysaccharides such as glucan, chitin, and mannan. The first two components primarily provide structure, while the mannan, often covalently linked to protein, constitutes the major antigen of the organism. Mannoproteins also have enzymatic activity (acid protease) and ligand-receptor functions. The complement receptors of C. albicans appear to be mannoproteins that are required for the adherence of the organism to endothelial cells. This is certainly true of the CR3-like protein of C. albicans. Proof that the CR3 is the Candida receptor for endothelial cells is derived from two observations. First, mutants lacking CR3 activity are less adherent in vitro and, in fact, less virulent. Second, the ligand recognized by the CR3 receptor (C3bi) as well as anti-CR3 antibodies blocks adherence of the organism to endothelial cells. The CR2 of C. albicans appears to promote the adherence of the organism to plastic substrates. Unlike the CR2 of mammalian cells, the Candida CR2 recognizes ligands containing the RGD sequence of amino acids in addition to the C3d ligand, which does not contain the RGD sequence. There is uncertainty as to whether the Candida CR2 and CR3 are, in fact, different proteins. A mannoprotein has also been described as the adhesin for epithelial cells. In this case, the receptor has a lectinlike activity and recognizes fucose- or glucosamine-containing glycoproteins of epithelial cells, depending on the strain of C. albicans. The oligosaccharide component of the receptor is probably not involved in ligand recognition and may serve to stabilize the receptor. However, the oligosaccharide factor 6 epitope of mannan may also provide adhesin activity in the recognition of epithelial cells. Mannoproteins can be extracted from cells by a number of reagents. Zymolyase, for instance, tends to remove structural mannoproteins, which contain relatively little protein and are linked to glucan. Reagents

  3. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    Sputtered coatings of the refractory metal carbides are of great interest for applications where hard wear-resistant materials are desired. The usefulness of sputtered refractory carbides is often limited, in practice, by spalling or interfacial separation. In this work improvements in the adherence of refractory carbides on iron, nickel and titanium based alloys were obtained by using oxidation, reactive sputtering or sputtered interlayers to alter the coating-substrate interfacial region. X-ray photoelectron spectroscopy and argon ion etching were used to characterize the interfacial regions, and an attempt was made to correlate adherence as measured in wear tests with the chemical nature of the interface.

  4. Strain monitoring of dual-room box-girder during prestressing tension based on fiber Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Jin, Tao; Zhu, Hongping; He, Weiping; Li, Ming

    2011-11-01

    Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaningful benefits when compared with the current solutions of an electric nature in recent years. In this study, several fiber Bragg grating (FBG) strain sensors were embedded into a prestressed concrete dual-room box-girder when construction at a prefabrication workshop to monitor strain of concrete girder during prestressing tension. All FBG sensors are alive during monitoring, which shows the advantages of robust surviving capability and long-term on-line monitoring performance. From the monitoring results it is found that the variances in strain at the measurement sites are small and almost is linear with time in certain one tension process, and the strain at the measurement sites almost synchronously and linearly change with the increase of the prestress. It is also found that the changes in strain at the measurement sites during the final tension are larger than that during the early tension.

  5. Strain monitoring of dual-room box-girder during prestressing tension based on fiber Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Jin, Tao; Zhu, Hongping; He, Weiping; Li, Ming

    2012-04-01

    Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaningful benefits when compared with the current solutions of an electric nature in recent years. In this study, several fiber Bragg grating (FBG) strain sensors were embedded into a prestressed concrete dual-room box-girder when construction at a prefabrication workshop to monitor strain of concrete girder during prestressing tension. All FBG sensors are alive during monitoring, which shows the advantages of robust surviving capability and long-term on-line monitoring performance. From the monitoring results it is found that the variances in strain at the measurement sites are small and almost is linear with time in certain one tension process, and the strain at the measurement sites almost synchronously and linearly change with the increase of the prestress. It is also found that the changes in strain at the measurement sites during the final tension are larger than that during the early tension.

  6. Improving Patient's Primary Medication Adherence

    PubMed Central

    Leguelinel-Blache, Géraldine; Dubois, Florent; Bouvet, Sophie; Roux-Marson, Clarisse; Arnaud, Fabrice; Castelli, Christel; Ray, Valérie; Kinowski, Jean-Marie; Sotto, Albert

    2015-01-01

    Abstract Quality of transitions of care is one of the first concerns in patient safety. Redesigning the discharge process to incorporate clinical pharmacy activities could reduce the incidence of postdischarge adverse events by improving medication adherence. The present study investigated the value of pharmacist counseling sessions on primary medication adherence after hospital discharge. This study was conducted in a 1844-bed hospital in France. It was divided in an observational period and an interventional period of 3 months each. In both periods, ward-based clinical pharmacists performed medication reconciliation and inpatient follow-up. In interventional period, initial counseling and discharge counseling sessions were added to pharmaceutical care. The primary medication adherence was assessed by calling community pharmacists 7 days after patient discharge. We compared the measure of adherence between the patients from the observational period (n = 201) and the interventional period (n = 193). The rate of patients who were adherent increased from 51.0% to 66.7% between both periods (P < 0.01). When discharge counseling was performed (n = 78), this rate rose to 79.7% (P < 0.001). The multivariate regression performed on data from both periods showed that age of at least 78 years old, and 3 or less new medications on discharge order were predictive factors of adherence. New medications ordered at discharge represented 42.0% (n = 1018/2426) of all medications on discharge order. The rate of unfilled new medications decreased from 50.2% in the observational period to 32.5% in the interventional period (P < 10−7). However, patients included in the observational period were not significantly more often readmitted or visited the emergency department than the patients who experienced discharge counseling during the interventional period (45.3% vs. 46.2%; P = 0.89). This study highlights that discharge counseling sessions are

  7. Role of flm Locus in Mesophilic Aeromonas Species Adherence

    PubMed Central

    Gryllos, Ioannis; Shaw, Jonathan G.; Gavín, Rosalina; Merino, Susana; Tomás, Juan M.

    2001-01-01

    The adherence mechanism of Aeromonas caviae Sch3N to HEp-2 cells was initially investigated through four mini-Tn5 mutants that showed a 10-fold decrease in adherence. These mutants lost motility, flagella, and their lipopolysaccharide (LPS) O antigen (O-Ag). Three genes, flmB-neuA-flmD, were found to be interrupted by the transposon insertions; additionally, two other genes, one lying upstream (flmA) and one downstream (neuB), were found to be clustered in the same operon. While the flmA and flmB genes were present in all mesophilic Aeromonas spp. (A. hydrophila, A. caviae, A. veronii bv. veronii, and A. veronii bv. sobria) tested, this was not the case for the neuA-flmD-neuB genes. Construction and characterization of flmB insertion mutants in five other mesophilic Aeromonas strains revealed the loss of motility, flagella, and adherence but did not alter the LPS composition of these strains. Taking the above findings into consideration, we conclude (i) that flagella and possibly the LPS O-Ag are involved in the adherence of the mesophilic Aeromonas to human epithelial cells; (ii) flmA and flmB are genes widely distributed in the mesophilic Aeromonas and are involved in flagella assembly, and thus adherence; and (iii) in A. caviae Sch3N the flmA and flmB genes are found in a putative operon together with neuA, flmD, and neuB and are involved in LPS O-Ag biosynthesis and probably have a role in flagellum assembly. PMID:11119490

  8. Radiation hard polyimide-coated FBG optical sensors for relative humidity monitoring in the CMS experiment at CERN

    NASA Astrophysics Data System (ADS)

    Makovec, A.; Berruti, G.; Consales, M.; Giordano, M.; Petagna, P.; Buontempo, S.; Breglio, G.; Szillasi, Z.; Beni, N.; Cusano, A.

    2014-03-01

    This work investigates the performance and the radiation hardness capability of optical thermo-hygrometers based on Fibre Bragg Gratings (FBG) for humidity monitoring in the Compact Muon Solenoid (CMS), one of the four experiments running at CERN in Geneva. A thorough campaign of characterization was performed on 80 specially produced Polyimide-coated RH FBG sensors and 80 commercial temperature FBG sensors. Sensitivity, repeatability and accuracy were studied on the whole batch, putting in evidence the limits of the sensors, but also showing that they can be used in very dry conditions. In order to extract the humidity measurements from the sensor readings, commercial temperature FBG sensors were characterized in the range of interest. Irradiation campaigns with ionizing radiation (γ-rays from a Co60 source) at incremental absorbed doses (up to 210 kGy for the T sensors and up to 90 kGy for the RH sensors) were performed on sample of T and RH-Sensors. The results show that the sensitivity of the sensors is unchanged up to the level attained of the absorbed dose, while the natural wavelength peak of each sensor exhibits a radiation-induced shift (signal offset). The saturation properties of this shift are discussed.

  9. 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

  10. Strain sensors for high field pulse magnets

    SciTech Connect

    Martinez, Christian; Zheng, Yan; Easton, Daniel; Farinholt, Kevin M; Park, Gyuhae

    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). Three 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.

  11. Performance of low-cost few-mode fiber Bragg grating sensor systems: polarization sensitivity and linearity of temperature and strain response.

    PubMed

    Ganziy, D; Rose, B; Bang, O

    2016-08-10

    We evaluate whether 850 nm fiber Bragg grating (FBG) sensor systems can use low-cost 1550 nm telecom fibers; in other words, how detrimental the influence of higher-order modes is to the polarization stability and linearity of the strain and temperature response. We do this by comparing polarization sensitivity of a few-mode 850 nm FBG sensor to a strictly single-mode 850 nm FBG sensor system using 850 nm single-mode fibers. We also compare the performance of the FBGs in strain and temperature tests. Our results show that the polarization stability and the linearity of the response degrade due to the presence of the higher-order modes. We demonstrate that, by using simple coiling of the 1550 nm fiber, one can regain the performance of the few-mode system and make it usable for high precision measurements. PMID:27534455

  12. 0.1-nano-strain resolution fiber optic sensor for quasi-static strain measurement with 1 kS/s sampling rate

    NASA Astrophysics Data System (ADS)

    Chen, Jiageng; Liu, Qingwen; Fan, Xinyu; Ma, Lin; Du, Jiangbing; Tokunaga, Tomochika; He, Zuyuan

    2015-09-01

    We present a newly developed high performance fiber optics sensor for quasi-static strain measurement. The sensor consists of a piece of π-phase shifted FBG for static strain sensing, and fiber Fabry-Perot interferometer for reference, interrogated by an improved sideband interrogation method with real-time feedback loops. Strain resolution of 0.12 nano-strain was achieved with sampling rate up to 1 kS/s in laboratory experiments. Compared with previous sensor systems, the proposed method shows great improvement in the sensing rate as well as the resolution.

  13. Experimental study of steel welded joints localization with using fiber Bragg grating strain sensor

    NASA Astrophysics Data System (ADS)

    Harasim, Damian

    2015-12-01

    Optical sensing systems has a not weakening research and development in recent years. Because of its unique properties of being unsusceptible to electromagnetic interference, having wide range of operational temperature and having extreme small physical dimensions, optical fiber sensors has increasing acceptance. Fiber Bragg Gratings (FBG) is the most frequently used type of optical sensor types because of its huge multiplexing potential and potentiality of being embedded into composite material (e.g. in structural health monitoring) or attached into measured structure. Embedding or attaching FBG into an inhomogeneous environment, spectral characteristic of the sensing grating do not retain full symmetry, which is due to related differences in the distribution of the axial stress of the grating. When periodicity of the grating is constant, the peak of FBG reflection spectrum should be narrow and sharp. An inhomogeneous axial strain distribution will cause a distorsion in measured transmission or reflection spectrum. This paper shows an distorsions in FBG reflection spectrum measured from sensor attached on surface with welded joint. The sensor strain-to-wavelength shift processing characteristics obtained for homogeneous and welded steel samples were compared.

  14. Characterization of the adherence properties of Streptococcus salivarius.

    PubMed Central

    Weerkamp, A H; McBride, B C

    1980-01-01

    The adherence and aggregation properties of 46 human oral Streptococcus salivarius isolates were examined. A total of 41% of the isolates aggregated with whole human saliva, 50% aggregated with human erythrocytes, and 85% adhered to human buccal epithelial cells. Strains that aggregated with saliva and erythrocytes usually reacted with Streptococcus group K typing serum whereas the non-hemagglutinating strains did not. K+ strains also adhered more strongly to human buccal epithelial cells than K- strains. All isolates coaggregated with Fusobacterium nucleatum LF and Bacteroides asaccharolyticus 2D, 91% coaggregated with Veillonella alcalescens V1, and 50% coaggregated with Veillonella parvula V4. S. salivarius HB aggregated with saliva from 15 different human donors and aggregated with human erythrocytes irrespective of the blood group. This strain only weakly aggregated with rat saliva or rat erythrocytes. We isolated mutants which concomitantly lost the ability to agglutinate erythrocytes, aggregate with saliva, and bind to buccal epithelial cells, but retained their interbacterial aggregation properties. A second class of mutants lost the ability to coaggregate with Veillonella, but these mutants retained all of the other aggregation properties. Treatment of S. salivarius HB cells with pronase or subtilisin destroyed their ability to aggregate with saliva and erythrocytes and to bind to buccal epithelial cells. The unique characteristics of the aggregation and adherence reactions were suggested by differences in the rate of loss of activity during protease treatment and in the response to chemical modification. The presence of saliva did not affect hemagglutination and adherence to buccal epithelial cells. Binding of the salivary aggregating factor to the bacteria could be distinguished from aggregation on the basis that the latter required divalent cations. The factor involved in coaggregation with F. nucleatum LF was physicochemically different from the other

  15. Improving medication adherence in migraine treatment.

    PubMed

    Seng, Elizabeth K; Rains, Jeanetta A; Nicholson, Robert A; Lipton, Richard B

    2015-06-01

    Medication adherence is integral to successful treatment of migraine and other headache. The existing literature examining medication adherence in migraine is small, and the methodologies used to assess adherence are limited. However, these studies broadly suggest poor adherence to both acute and preventive migraine medications, with studies using more objective monitoring reporting lower adherence rates. Methods for improving medication adherence are described, including organizational strategies, provider-monitoring and self-monitoring of adherence, regimen strategies, patient education, self-management skills training (e.g., stimulus control, behavioral contracts), and cognitive-behavioral therapy techniques. The article concludes by discussing the future of research regarding adherence to medications for migraine and other headaches. PMID:26040703

  16. Factors influencing human leukocyte adherence in vitro.

    PubMed

    Stepniewicz, W; Tchórzewski, H; Luciak, M

    1983-01-01

    Studies were performed on factors influencing leucocyte adherence in vitro. Blood condensation was found to increase leukocyte adherence. Addition of heparin, dextran or ethanol caused a significant reduction of white blood cell count in blood samples in comparison with blood mixed with sodium EDTA or ACD solution. This suggests the existence of two granulocyte subpopulations; viz, rapidly adhering and slowly adhering. Heparin enhanced granulocyte adherence, while dextran and ethanol decreased it. Five-day storage of ACD blood led to a decrease in granulocyte adherence, while addition of heparin or histamine to ACD blood prevented this change to occur. The glucose concentration of 1,000 mg/dl augmented granulocyte adherence, while higher glucose concentrations induced its progressive fall below the control values. There was no significant change of lymphocyte adherence during the experiments. PMID:6194070

  17. 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.

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

    SciTech Connect

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

    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 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 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 nozzle

  19. 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. PMID:26736396

  20. Innovative FBG sensing techniques for the railway industry: application to overhead contact line monitoring

    NASA Astrophysics Data System (ADS)

    Laffont, Guillaume; Roussel, Nicolas; Rougeault, Stéphane; Boussoir, Jonathan; Maurin, Laurent; Ferdinand, Pierre

    2009-10-01

    Current collection is a key issue in modern electrical railway, and its performances are mainly determined by the pantograph/catenary interactions. Whilst being the less investigated topic, the pantograph/catenary mechanical interface is the most crucial one. Many incidents and traffic interruptions are due to degraded, or even damaged, electrical contacts between current collectors and contact wires. During the 6th European Framework Program (FP6) CATIEMON project (CATenary InterfacE MONitoring), both FBG-based sensors and systems dedicated to the pantograph/catenary interaction monitoring - directly from the high voltage contact wire - have been developed and tested. This paper describes their design and installation but also results coming from field-tests. It highlights their advantages for the railway stakeholders and end-users in term of train operation enhancement.

  1. 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.

  2. Force and temperature characteristics of a fs-laser machined locally micro-structured FBG

    NASA Astrophysics Data System (ADS)

    Dutz, Franz J.; Marchi, Gabriele; Stephan, Valentin; Huber, Heinz P.; Roths, Johannes

    2016-05-01

    A locally micro-structured fiber Bragg grating (LMFBG) was manufactured by forming a circumferential groove in the middle of a type I fiber Bragg grating (FBG). The groove was directly ablated using a fs-laser and had a length of 86μm, a depth of 27μm and steep side walls. Due to the precisely machined geometry of the structure the reflection spectra can be accurately described with a fairly simple theoretical model. At several constant temperatures in the range from 5°C to 45°C this structure was exposed to various compressive loads in the range from 0N to -1.42N. Here the force and temperature sensitivity of the LMFBG are presented. This structure can be used for miniaturized compressive force sensing at variable temperatures, which is of particular interest for many bio-medical applications.

  3. 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.

  4. Adherence of Veillonella Species Mediated by Extracellular Glucosyltransferase from Streptococcus salivarius

    PubMed Central

    McCabe, R. M.; Donkersloot, J. A.

    1977-01-01

    The effect of extracellular products from Streptococcus salivarius on sucrose-dependent adherence to smooth surfaces by other oral bacteria was studied in vitro. Strains of Streptococcus mitis, Streptococcus pyogenes, and Veillonella parvula without innate ability to adhere to a steel wire were able to do so when incubated with sucrose and cell-free culture fluid from S. salivarius strains 9759, 25975, CNII, and MEPI. These culture fluids synthesized more adherent material and water-insoluble glucan than those from Streptococcus mutans C67-1 and seven other S. salivarius strains. Among the S. salivarius strains, glucosyltransferase (GT; dextransucrase, EC 2.4.1.5) activity varied more than 100-fold. Cells of Veillonella and S. mitis S3 that had been incubated in culture fluids from S. salivarius 25975 and 9759, respectively, and then washed adhered upon subsequent incubation with sucrose. This was due to adsorbed GT because (i) the adherence was sensitive to dextranase; (ii) it was observed only with the high-GT culture fluids; (iii) it was dependent on sucrose; and (iv) the washed Veillonella cells synthesized glucan, but not fructan, from sucrose. These results suggest that sucrose-dependent adherence of bacteria without such innate ability can be mediated by (i) entrapment in insoluble glucan synthesized by S. salivarius culture fluids, and (ii) prior adsorption of GT from S. salivarius culture fluids. The possibility that GT formed by high-yield strains of S. salivarius is distributed through the mouth by the action of salivary flow and contributes to sucrose-dependent adherence and plaque formation is considered. Images PMID:591064

  5. Temperature and strain effects discrimination inside composite materials with embedded weakly tilted fibre Bragg grating

    NASA Astrophysics Data System (ADS)

    Kinet, D.; Garray, D.; Mégret, P.; Caucheteur, C.

    2013-05-01

    Fibre Bragg gratings (FBGs) are strain sensors that can be embedded into composite materials, without affecting their mechanical performances. In this study, we report the use of a short and weakly tilted FBG inscribed in a single mode highly germanium doped photosensitive optical fibre to discriminate, with a good spatial resolution, strain and temperature effects for structural health monitoring (SHM) application. The transmission spectrum of a weakly tilted FBG (TFBG) presents three regions of interest: the Bragg resonance, the ghost mode resonance and all other cladding mode resonances that are not exploited in this work. We make use of the differential temperature sensitivity of the Bragg mode and the ghost mode to discriminate between temperature and strain effects inside composite materials.

  6. Enhancing Adherence in Clinical Exercise Trials.

    ERIC Educational Resources Information Center

    O'Neal, Heather A.; Blair, Steven N.

    2001-01-01

    Discusses exercise adherence from the perspective of adhering to an exercise treatment in a controlled trial, focusing on: adherence (to intervention and measurement); the development of randomized clinical trials; exemplary randomized clinical trials in exercise science (exercise training studies and physical activity interventions); and study…

  7. Strain and high-temperature discrimination using a Type II fiber Bragg grating and a miniature fiber Fabry-Perot interferometer.

    PubMed

    Jiang, Yajun; Yang, Dexing; Yuan, Yuan; Xu, Jian; Li, Dong; Zhao, Jianlin

    2016-08-10

    A novel method for simultaneous measurement of strain and high temperature using a Type II fiber Bragg grating (FBG) and a miniature fiber Fabry-Perot interferometer (MFFPI) is proposed. The MFFPI is produced by fusion splicing a short section of quartz capillary tube with two single-mode fibers, and then it is exposed by a focused femtosecond laser and a phase mask to inscribe a Type II FBG nearby. The reflection spectrum of this sensor is the superposition of the reflection spectrum of the FBG and the interference fringe of the MFFPI. This sensor shows perfect high-temperature and strain responses. Because of the different responses to the uniform variations of strain and temperature, by measuring the reflection peak of FBG and one of the interference dips of the MFFPI, strain and temperature can be simultaneously determined. The resolutions of this particular sensor in measuring strain and temperature are estimated to be ±8.4  μϵ and ±3.3°C, respectively, in the range from 0 to 1122 μϵ and from 23°C to 600°C. PMID:27534477

  8. Ultrahigh resolution fiber-optic quasi-static strain sensors for geophysical research

    NASA Astrophysics Data System (ADS)

    He, Zuyuan; Liu, Qingwen; Tokunaga, Tomochika

    2013-12-01

    A review of our recent work on ultrahigh resolution optical fiber sensors in the quasi-static region is presented, and their applications in crustal deformation measurement are introduced. Geophysical research such as studies on earthquake and volcano requires monitoring the earth's crustal deformation continuously with a strain resolution on the order of nano-strains (nɛ) in static to low frequency region. Optical fiber sensors are very attractive due to their unique advantages such as low cost, small size, and easy deployment. However, the resolution of conventional optical fiber strain sensors is far from satisfactory in the quasi-static domain. In this paper, several types of recently developed fiber-optic sensors with ultrahigh resolution in the quasi-static domain are introduced, including a fiber Bragg grating (FBG) sensor interrogated with a narrow linewidth tunable laser, an FBG based fiber Fabry-Perot interferometer (FFPI) sensor by using a phase modulation technique, and an FFPI sensor with a sideband interrogation technique. Quantificational analyses and field experimental results demonstrated that the FBG sensor can provide nano-order strain resolution. The sub-nano strain resolution was also achieved by the FFPI sensors in laboratory. Above achievements provide the basis to develop powerful fiber-optic tools for geophysical research on crustal deformation monitoring.

  9. How can we improve adherence?

    PubMed

    Price, Patricia

    2016-01-01

    Many patients with wound healing difficulties are also coping with the management of a chronic disease or chronic condition that requires them to make lifestyle behaviour changes, for example, managing glucose levels through diet and exercise and regular foot inspection. Many find it difficult to make such changes and often experience feelings of powerlessness when faced with a lifetime of behavioural and psychological change. This article will explore the importance of understanding the patient difficulties associated with adherence to a regime and how life changes can be difficult to maintain over sustained periods of time. However, the article will also discuss the importance of this topic in trying to understand the clinical evidence base for treatment--as many clinical trials investigating treatments for the diabetic foot do not include information on the extent to which patients in the trial conformed to the trial protocol. The article gives an overview of recent developments--including lessons we can learn from other chronic conditions where permanent life changes are required--in particular the need to keep health messages simple, tailored to the individual and repeated frequently. The evidence to date suggests that no one single form of adherence intervention will work with all patients; this is not surprising given complex and multifactorial nature of adherence and the myriad of barriers that exist that patients and health care professionals need to overcome. PMID:26453542

  10. [Long term adherence to HAART in Senegal].

    PubMed

    Bastard, M; Fall, M Basty Koita

    2014-10-01

    Adherence is one of the main predictors of antiretroviral treatment success. A governmental initiative was launched in 1998 for HIV-infected patients in Senegal to provide access to highly active antiretroviral therapy (HAART). Adherence measurements, defined as pills taken/pills prescribed, were assessed between November 1999 and June 2010 using a pill count along with a questionnaire for 330 patients. Predictors of adherence and identification of adherence trajectories were explored through latent class mixed model. We also performed a survival analysis using Cox proportional hazard model. Three adherence behaviours were revealed as well as a better adherence for women. A third of patients had a high adherence trajectory over time and a third had an intermediate one. Male gender and low adherence behaviour over time were independently associated with a higher mortality rate. This study shows that an overall good adherence can be obtained in the long term in Senegal, suggests a better adherence for women and points out a large subsample of patients with intermediate level of adherence behaviour who are at risk for developing resistance to antiretroviral drugs. PMID:24615434

  11. Bisphosphonates adherence for treatment of osteoporosis

    PubMed Central

    2013-01-01

    Background Osteoporosis is a disease of bone metabolism in which bisphosphonates (BPS) are the most common medications used in its treatment, whose main objective is to reduce the risk of fractures. The aim of this study was to conduct a systematic review on BPs adherence for treatment of osteoporosis. Methods Systematic review of articles on BPs adherence for treatment of osteoporosis, indexed on MEDLINE (via PubMed) databases, from inception of databases until January 2013. Search terms were “Adherence, Medication” (MeSH term), “Bisphosphonates” (MeSH term), and “Osteoporosis” (MeSH term). Results Of the 78 identified studies, 27 met the eligibility criteria. Identified studies covered a wide range of aspects regarding adherence and associated factors, adherence and fracture, adherence and BPs dosage. The studies are mostly observational, conducted with women over 45 years old, showing low rates of adherence to treatment. Several factors may influence adherence: socio-economic and cultural, participation of physicians when guidance is given to the patient, the use of bone turnover markers, and use of generic drugs. The monthly dosage is associated with greater adherence compared to weekly dosage. Conclusions Considering the methodological differences between the studies, the results converge to show that adherence to treatment of osteoporosis with BPs is still inadequate. Further experimental studies are needed to evaluate the adherence and suggest new treatment options. PMID:23705998

  12. Small-diameter optical fiber and high-speed wavelength interrogator for FBG/PZT hybrid sensing system

    NASA Astrophysics Data System (ADS)

    Komatsuzaki, Shinji; Kojima, Seiji; Hongo, Akihito; Takeda, Nobuo; Sakurai, Takeo

    2007-04-01

    We have been developing a sensing system for checking the health of aircraft structures made of composite materials. In this system, lead zirconium titanate (PZT) actuators generate elastic waves that travel through the composite material and are received by embedded fiber Bragg grating (FBG) sensors. By analyzing the change in received waveforms, we can detect various kinds of damage. The frequency of the elastic waves is several hundred kHz, which is too high for a conventional optical spectrum analyzer to detect the wavelength change. Moreover, a conventional single-mode optical fiber cannot be used for an embedded FBG sensor because it is so thick that it induces defects in the composite material structure when it is embedded. We are thus developing a wavelength interrogator with an arrayed waveguide grating (AWG) that can detect the high-speed wavelength change and a small-diameter optical fiber (cladding diameter of 40µm) that does not induce defects. We use an AWG to convert the wavelength change into an output power change by using the wavelength dependency of the AWG transmittance. For this conversion, we previously used two adjacent output ports that cover the reflection spectrum of an FBG sensor. However, this requires controlling the temperature of the AWG because the ratio of the optical power change to the wavelength change is very sensitive to the relationship of the center wavelengths between an FBG sensor and the output ports of the AWG. We have now investigated the use of a denser AWG and six adjacent output ports, which covers the reflection spectrum of an FBG sensor, for detecting the elastic waves. Experimental results showed that this method can suppress the sensitivity of the power change ratio to the relationship of the center wavelengths between an FBG sensor and the output ports. Although our improved small-diameter optical fiber does not induce structural defects in the composite material when it is embedded, there is some micro or macro

  13. Adherence to Methotrexate therapy in Rheumatoid Arthritis

    PubMed Central

    Arshad, Nasim; Ahmad, Nighat Mir; Saeed, Muhammad Ahmed; Khan, Saira; Batool, Shabnam; Farman, Sumaira

    2016-01-01

    Objective: To determine adherence to methotrexate (MTX) therapy in patients with Rheumatoid Arthritis (RA) and to identify factors that promote either adherence or non adherence. Methods: One hundred Rheumatoid Arthritis patients on MTX for at least two months were enrolled. Questionnaire was completed by direct interview. Details recorded were, demographics (age, sex, education, monthly income), disease duration, duration on MTX and current dose. Disease Activity Score on 28 joint counts (DAS 28) at the current visit, concomitant drugs taken and number of doses of MTX missed in the previous 8 weeks were noted. Non adherence was defined as omission of any three or more prescribed doses of MTX in previous 8 week. Patients were asked for the factors that motivated their adherence to MTX as well as factors for non adherence. Presence of side effects due to MTX was also recorded. Result: Non adherence was found among 23% of cases. Patients of low socioeconomic group (p <0.0001) and on MTX for longer duration (p <0.001) had higher non adherence. Non adherent patients had significantly higher disease activity as measured by DAS 28 (p<0.001). Good counseling and education by the doctor was a strong predictor of adherence (p <0.001). Lack of affordability (p <0.001); lack of availability at local pharmacy (p <0.001); lack of family support (p <0.001) and lack of awareness regarding need and importance of MTX (p < 0.001were found as significant factors for non adherence. Conclusion: MTX non adherence in RA is noted in about one fourth of study group. Various economical and social issues lead to non adherence but good patient education and counseling by doctor could promote adherence in this study group. PMID:27182251

  14. 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.

  15. Adherence of Entamoeba histolytica trophozoites to rat and human colonic mucosa.

    PubMed Central

    Ravdin, J I; John, J E; Johnston, L I; Innes, D J; Guerrant, R L

    1985-01-01

    We studied the adherence of [3H]thymidine-labeled axenic Entamoeba histolytica (strain HM1-IMSS) to in vitro preparations of rat and human colonic mucosa. Studies were performed with fixed or unfixed rat colonic mucosa, unfixed rat mucosa exposed to trypsin, unfixed rat submucosa, and fixed human colonic mucosa. Twenty percent of the amebae adhered to fixed rat colonic mucosa; adherence was specifically inhibited by N-acetyl-D-galactosamine (GalNAc), galactose, and asialofetuin. The adherence of amebae to fixed human colonic mucosa was also GalNAc inhibitable. Greater adherence was found with unfixed rat colonic mucosa (40.9%) and was not GalNAc inhibitable unless the tissue was first exposed to trypsin. However, GalNAc did inhibit the adherence of amebae to unfixed rat submucosa. Glutaraldehyde fixation of amebae inactivates known amebic adhesion proteins; there was a markedly decreased adherence of fixed amebae to trypsin-exposed mucosa or fixed rat colonic mucosa. However, fixed or viable amebae had equal levels of adherence to unfixed rat colonic mucosa, suggesting the presence of a host adhesion protein that binds to receptors on amebae. Human (10%) and rabbit (5%) immune sera reduced the adherence of viable amebae to fixed rat colonic mucosa. We concluded that the GalNAc-inhibitable adhesion protein on the surface of E. histolytica trophozoites mediated adherence to fixed rat mucosa, fixed human colonic mucosa, trypsin-exposed unfixed rat mucosa, and unfixed rat submucosa. The surface of unfixed rat colonic mucosa contained a glutaraldehyde- and trypsin-sensitive host adhesion protein, perhaps in the overlying mucus blanket, which bound viable or fixed E. histolytica trophozoites. Images PMID:2580787

  16. Distributed fiber Brillouin strain sensing by correlation-based continuous-wave technique: cm-order spatial resolution and dynamic strain measurement

    NASA Astrophysics Data System (ADS)

    Hotate, Kazuo; Ong, Sean S.

    2002-09-01

    This paper describes a novel correlation-based technique for fiber optic distributed strain sensors using Brillouin scattering. Conventional Brillouin-based sensors utilize a pulsed-pump similar to that of OTDR and are capable of distributed strain sensing over large distances, but suffer an inherent spatial resolution limit of around 1m. In addition, unlike FBG-based strain sensors which are competent of measuring dynamic strain, the pulse-based Brillouin sensors have large measurement times of several minutes, making them inadequate for dynamic strain measurements. On the other hand, using the correlation-based continuous-wave technique, we have achieved static distributed strain measurements of up to 1cm spatial resolution, and dynamic strain measurements of up to 8.8Hz from a 5cm strained section.

  17. Research on influence of environmental conditions on measurement performance of magnetic field sensor based on differential group delay in FBG

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Wang, Haitong; Li, Yaocheng

    2015-02-01

    According to the sensing principle of FBG, the measurement performance of magnetic field sensor based on the differential group delay (DGD) in FBG is discussed in this article. The influence of external environmental parameters, including temperature, stress and pressure, on magnetic field sensor based on DGD are then analyzed from the aspect of theory and simulated through Matlab. As the simulation results indicates, the magnetic field sensing scheme based on DGD is not sensitive to temperature and stress, the specific performance is that the changing temperature or stress can make the DGD spectrum move along the horizontal axis (the wavelength), with the shape unchanged; when temperature variation or phase axial stress maintains the same, the DGD has a linear relation with the magnetic induction intensity. While the external pressure has serious impact on the magnetic field sensing scheme, which is apparently embodied in nonlinear and irregular change of DGD spectrum with the varying pressure.

  18. Medication Adherence in People With Parkinson Disease.

    PubMed

    Shin, Ju Young; Habermann, Barbara

    2016-01-01

    Parkinson disease (PD) is the second most common neurodegenerative disorder in the United States. Because there is no cure for PD currently, pharmacological therapy is the mainstay of PD symptom management. Despite the importance of medication adherence in PD, several studies have reported medication nonadherence and/or suboptimal adherence. This literature review provides an overview of medication adherence issues in people with PD. Articles were identified for this study using computerized database searches and journal hand searches. Of the 72 medication adherence articles reviewed, the following articles were eligible for this review: (a) 10 articles measuring medication adherence in people with PD, (b) four medication adherence intervention articles, and (c) six studies of medication adherence in hospitalized settings. The importance of adherence assessment and strategies in improving medication adherence are discussed with the goal of improving symptom management and clinical outcomes in people with PD. Because medication taking is a complex and multifaceted phenomena, patient-centered, theory-driven interventions are needed to improve medication adherence and quality of care and life in people with PD. PMID:27224682

  19. Role of Thin Fimbriae in Adherence and Growth of Acinetobacter calcoaceticus RAG-1 on Hexadecane.

    PubMed

    Rosenberg, M; Bayer, E A; Delarea, J; Rosenberg, E

    1982-10-01

    Acinetobacter calcoaceticus RAG-1, a hydrocarbon-degrading bacterium which adheres avidly to hydrocarbons and other hydrophobic surfaces, possesses numerous thin fimbriae (ca. 3.5-nm diameter) on the cell surface. MR-481, a nonadherent mutant of RAG-1 which is unable to grow on hexadecane under conditions of limited emulsification and low initial cell density, lacks these fimbriae. Prolonged incubation of MR-481 in hexadecane medium enriched for partial adherence revertants. The reappearance of thin fimbriae was observed in all such revertant strains. RAG-1 cells and partial revertant strains were agglutinated in the presence of antibody, whereas MR-481 cells were not. Another mutant, AB15, which was previously isolated on the basis of its nonagglutinability in the presence of antibody, also lacked thin fimbriae and was conditionally nonadherent. Furthermore, strain AB15 was unable to grow on hexadecane medium. Adherence of RAG-1 cells to hexadecane was considerably reduced after shearing treatment. The material removed from the cell surface by shearing of RAG-1 and the partial revertant strains yielded a single antigenic band in RAG-1 and partial revertant strains, as observed by crossed immunoelectrophoresis. This band was absent in both fimbriae-less mutants, MR-481 and AB15. The data demonstrate that the thin fimbriae of RAG-1 (i) are a major factor in adherence to polystyrene and hydrocarbon, (ii) may be crucial in enabling growth of cells on hexadecane, and (iii) constitute the major cell surface agglutinogen. PMID:16346118

  20. Role of Thin Fimbriae in Adherence and Growth of Acinetobacter calcoaceticus RAG-1 on Hexadecane

    PubMed Central

    Rosenberg, Mel; Bayer, Edward A.; Delarea, Jacob; Rosenberg, Eugene

    1982-01-01

    Acinetobacter calcoaceticus RAG-1, a hydrocarbon-degrading bacterium which adheres avidly to hydrocarbons and other hydrophobic surfaces, possesses numerous thin fimbriae (ca. 3.5-nm diameter) on the cell surface. MR-481, a nonadherent mutant of RAG-1 which is unable to grow on hexadecane under conditions of limited emulsification and low initial cell density, lacks these fimbriae. Prolonged incubation of MR-481 in hexadecane medium enriched for partial adherence revertants. The reappearance of thin fimbriae was observed in all such revertant strains. RAG-1 cells and partial revertant strains were agglutinated in the presence of antibody, whereas MR-481 cells were not. Another mutant, AB15, which was previously isolated on the basis of its nonagglutinability in the presence of antibody, also lacked thin fimbriae and was conditionally nonadherent. Furthermore, strain AB15 was unable to grow on hexadecane medium. Adherence of RAG-1 cells to hexadecane was considerably reduced after shearing treatment. The material removed from the cell surface by shearing of RAG-1 and the partial revertant strains yielded a single antigenic band in RAG-1 and partial revertant strains, as observed by crossed immunoelectrophoresis. This band was absent in both fimbriae-less mutants, MR-481 and AB15. The data demonstrate that the thin fimbriae of RAG-1 (i) are a major factor in adherence to polystyrene and hydrocarbon, (ii) may be crucial in enabling growth of cells on hexadecane, and (iii) constitute the major cell surface agglutinogen. Images PMID:16346118

  1. Characterization of embedded fiber optic strain sensors into metallic structures via ultrasonic additive manufacturing

    NASA Astrophysics Data System (ADS)

    Schomer, John J.; Hehr, Adam J.; Dapino, Marcelo J.

    2016-04-01

    Fiber Bragg Grating (FBG) sensors measure deviation in a reflected wavelength of light to detect in-situ strain. These sensors are immune to electromagnetic interference, and the inclusion of multiple FBGs on the same fiber allows for a seamlessly integrated sensing network. FBGs are attractive for embedded sensing in aerospace applications due to their small noninvasive size and prospect of constant, real-time nondestructive evaluation. In this study, FBG sensors are embedded in aluminum 6061 via ultrasonic additive manufacturing (UAM), a rapid prototyping process that uses high power ultrasonic vibrations to weld similar and dissimilar metal foils together. UAM was chosen due to the desire to embed FBG sensors at low temperatures, a requirement that excludes other additive processes such as selective laser sintering or fusion deposition modeling. In this paper, the embedded FBGs are characterized in terms of birefringence losses, post embedding strain shifts, consolidation quality, and strain sensing performance. Sensors embedded into an ASTM test piece are compared against an exterior surface mounted foil strain gage at both room and elevated temperatures using cyclic tensile tests.

  2. 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

  3. High temperature strain sensor based on a fiber Bragg grating and rhombus metal structure.

    PubMed

    Zhang, Liang; Liu, Yueming; Gao, Xiaoliang; Xia, Zhongcheng

    2015-10-01

    In this paper, a novel high temperature strain sensor based on a polyimide-coated fiber Bragg grating (FBG) and a rhombus metal structure is presented and experimentally demonstrated. By heating low softening point glass via a micro torch, the polyimide-coated FBG could be fixed into the rhombus metal structure. Consequently, when the rhombus structure is stretched and compressed, respectively, then the FBG will be subjected to a reverse state. Moreover, the strain sensitivity is controllable and enhanced by adjusting the dimension of the rhombus metal structure appropriately. The experiment was then carried out by using an equi-intensity cantilever beam and high temperature chamber, and the result showed that the proposed high temperature strain sensor could be used at the high temperature of 300°C. A resolution of ∼10  με has been experimentally achieved. The average wavelength strain sensitivity at 300°C is 1.821 and 1.814 pm/με, for the compressed and stretched states, respectively. PMID:26479639

  4. Dynamic fiber Bragg grating strain sensor using a wavelength-locked tunable fiber ring laser

    NASA Astrophysics Data System (ADS)

    Zhu, Yinian; Krishnaswamy, Sridhar

    2012-04-01

    The interrogation systems based on fiber-optic sensors are very attractive for the practical applications in structural health monitoring owing to a number of advantages of optical fiber elements over their electronic counterparts. Among the fiber-optic sensors, the fiber Bragg gratings (FBGs) have their own unique features to be widely used for detection of acoustic emission. We have developed a dynamic strain sensing system by using a tunable single longitudinal mode Erbium-doped fiber ring laser to be locked to the middle-reflection wavelength of the FBG as the demodulation technique. A proportional-integral-derivative device continuously controls the laser wavelength that is kept at the FBG middle-reflection wavelength, thus stabilizing the operating point against quasi-static perturbation, while the high frequency dynamic strain shifts the FBG reflection profile. The reflected power varies in proportion to the applied strain which can be derived directly from AC photocurrent of the reflected signal. We have designed and assembled a fourchannel demodulator system for simultaneous high frequency dynamic strain sensing.

  5. Method of simultaneous measurement of two direction force and temperature using FBG sensor head.

    PubMed

    Kisała, Piotr; Cięszczyk, Sławomir

    2015-04-01

    This paper presents a method for measuring two components of bending force and temperature using one sensor head. Indirect inference based on the spectra of two fiber Bragg gratings (FBGs) placed on a cantilever beam is used. The method was developed during work on the inverse problem of determining a nonuniform stress distribution based on FBG spectra. A gradient in the FBG stress profile results in a characteristic shape of its reflective spectrum. The simultaneous measurements of force and temperature were possible through the use of an appropriate layout of the sensor head. The spectral characteristics of the sensor's gratings do not retain full symmetry, which is due to the geometry of the sensor's head and the related difference in the distribution of the axial stress of the gratings. In the proposed approach, the change in width of the sum of the normalized transmission spectra was used to determine the value of the applied force. In the presented method, an increase in the sensitivity of this change to the force is obtained relative to the other known systems. A change in the spectral width was observed for an increase in bending forces from 0 to 150 N. The sensitivity coefficient of the spectral width to force, defined as the ratio of the change of the spectral half-width to the change in force was 2.6e-3  nm/N for the first grating and 1.2e-3  nm/N for the second grating. However, the sensitivity of the whole sensor system was 5.8e-3  nm/N, which is greater than the sum of the sensitivities of the individual gratings. For the purpose of this work, a station with a thermal chamber has been designed with a bracket on which fiber optic transducers have been mounted for use in further measurements. The sensor head in this experiment is considered to be a universal device with potential applications in other types of optical sensors, and it can be treated as a module for development through its multiplication on a single optical fiber. PMID

  6. Development of damage monitoring system for aircraft structure using a PZT actuator/FBG sensor hybrid system

    NASA Astrophysics Data System (ADS)

    Ogisu, Toshimichi; Shimanuki, Masakazu; Kiyoshima, Satoshi; Okabe, Yoji; Takeda, Nobuo

    2004-07-01

    This paper presents a part of the research results on a damage monitoring system using PZT actuators/FBG sensors for advanced composite material structures of new-generation aircrafts. To achieve weight reduction of the aircraft structure, these advanced composite materials have gradually been employed for the primary structure. It is expected that when these materials are extensively employed, an efficient bonded structure such as a hat-shaped stringer will be utilized for the aircraft structure. However, these bonded structures have critical problems such as debonding and delamination at the interfaces of the laminate. Further, a single-step molding process of the structure elements is necessary in order to ensure low cost and thus affordability. However, this low-cost process results in an increase in the non-destructive inspection (NDI) cost. Therefore, an innovative damage monitoring system is required for structural health management. In the present study, the authors have developed a hybrid sensor system that can detect the elastic waves launched from the piezo transducer (PZT) actuator using a high-speed and high-accuracy fiber Bragg grating (FBG) sensor to resolve the issues mentioned above. In this study, the conceptual design of an aircraft that can employ this damage monitoring system was carried out. Subsequently, the application area was selected based on cases of certain kinds of damage. Further, the validity of the damage monitoring system for the verification of the structural integrity of the aircraft was discussed. Next, in order to verify the elastic wave detectability of the FBG sensor, it was confirmed that an elastic wave of 300 kHz is detectable at a distance of 5 cm between the PZT actuator and FBG sensor using an aluminum sheet and CFRP cross-ply laminate and also by considering the relationship between sensor length and sensitivity. Through the present research results, the possibility of applying the damage monitoring system to the

  7. Wing shaping and strain sensing using fiber optics

    NASA Astrophysics Data System (ADS)

    Mendoza, Sergio Licon

    Current technologies to measure strain rely on strain gauges that become heavy with increased measurement points. One significant improvement is the Fiber Bragg Gratings (FBG) which allows light to reflect through a fiber optic line in relation to the strain applied on that fiber. Significant advantages over conventional strain gauges allow for a light weight detailed view of the strain applied to any structure containing these fibers. The SPACE Center in conjunction with the AERO Institute have produced preliminary conclusions on how to implement such fibers on a wing structure and how they could be used to control the shape of a wing. Such a wing structure could be built lighter and flexible than today's wings thus enabling a lighter aircraft. Further studies show that if a feedback mechanism is encompassed, flutter suppression techniques can be accomplished with the use of these fibers thus avoiding catastrophic failure.

  8. Demonstration of detectability of SHM system with FBG/PZT hybrid system in composite wing box structure

    NASA Astrophysics Data System (ADS)

    Soejima, Hideki; Ogisu, Toshimichi; Yoneda, Hiroshi; Okabe, Yoji; Takeda, Nobuo; Koshioka, Yasuhiro

    2008-03-01

    We have developed a novel damage monitoring system that can monitor the integrity of composite structures in aircrafts. In this system, fiber Bragg grating (FBG) sensors are used as sensors and piezoelectric transducers (PZT) are used as the generators of elastic waves that propagate in the structure to be inspected. The damage monitoring system can detect the structural integrity by the change in elastic waves that are detected by the FBG sensor and arrayed waveguide grating (AWG)-type filter. We confirmed that the structure health monitoring (SHM) system was able to monitor the damage initiation and propagation by a change in the waveform of the elastic waves in coupon specimens and structural element specimens. In this study, we demonstrate the detectability of the damage monitoring system by using a subcomponent test specimen that simulates an actual aircraft wing box structure composed of carbon fiber reinforced plastics (CFRPs). The FBG sensors and PZTs are bonded to the surfaces of hat-shaped stringers by an adhesive. Damages such as de-bonding and delamination are introduced in the bonded sections of the skin and stringers by impact. Damage monitoring and diagnosis are carried out by the SHM system under ambient conditions. We successfully verify the detectability of our system.

  9. 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

  10. Soil adherence to human skin

    SciTech Connect

    Driver, J.H.; Konz, J.J.; Whitmyre, G.K. )

    1989-12-01

    Dermal exposure to soils contaminated with toxic chemicals represents a potential public health hazard. These soils, contaminated with chemicals such as PCBs and dioxins, may be found at various locations throughout the US. Furthermore, dermal contact with pesticide-containing particles and contaminated soil particles is of importance for exposures to agricultural workers who reenter fields after pesticide application. With respect to dermal exposure to pesticide-contaminated particulate matter, several occurrences of human toxicity to ethyl parathion in citrus groves have been reported. These exposures resulted from dermal contact with high concentrations of the toxic transformation product paraoxon in soil dust contaminated as a result of application of pesticide to the overhead foliage of trees. To assess dermal exposure to chemically-contaminated soil at sites of concern, dermal adherence of soil must be determined prior to the assessment of dermal absorption. The purpose of the experiment reported herein was to determine the amount of soil (mg/cm{sup 2}) that adheres to adult hands under various soil conditions. These conditions include the type of soil, the organic content of the soil, and the particle size of the soil.

  11. Integrated real-time monitoring system for strain/temperature distribution based on simultaneous wavelength and time division multiplexing technique

    NASA Astrophysics Data System (ADS)

    Dai, Yongbo; Li, Peng; Liu, Yanju; Asundi, Anand; Leng, Jinsong

    2014-08-01

    Based on the combination of wavelength- and time-division multiplexing technique, a novel fiber Bragg grating (FBG) sensor multiplexing system is proposed, which can be used for monitoring the two-dimensional strain and temperature field distribution in large structures. The FBG sensing unit is encoded simultaneously in both wavelength and time domains. Using the semiconductor optical amplifier (SOA) resonant cavity technology, a large capacity multiplexing technology with mixed time-division and wave-division multiplexing (TDM+WDM) is presented. The sensor array contains many groups with each group composed of many sensors. The group is addressed by TDM mode and each sensor of the groups is accessed by WDM mode. Therefore, the total multiplexing capacity is multiplication of TDM and WDM. In theory, more than 1000 sensors can be multiplexed on one single fiber. The feasibility of the scheme was experimentally demonstrated through a sensor system with a two dimensional FBG sensing network with 5×5 sensors arrays. In addition, the strain/temperature distribution in an aluminum plate was measured at real time under different loading/heating by using above FBG sensing network.

  12. Improving hand hygiene adherence among nursing staff.

    PubMed

    Harne-Britner, Sarah; Allen, Marianne; Fowler, Kimberly A

    2011-01-01

    This quasi-experimental study explored initial and sustained effects of educational and behavioral interventions on hand hygiene adherence and the relationships between hand hygiene adherence and health care-associated infections. Education paired with positive reinforcement behavioral interventions significantly improved hand hygiene adherence after the first month (χ² = 4.27; P = .039); however, the improvement was not sustained over 6 months. There were no significant differences in infection rates between the treatment and control groups. PMID:20407392

  13. Patient Characteristics Associated with Medication Adherence

    PubMed Central

    Rolnick, Sharon J; Pawloski, Pamala A.; Hedblom, Brita D.; Asche, Stephen E.; Bruzek, Richard J.

    2013-01-01

    Objective Despite evidence indicating therapeutic benefit for adhering to a prescribed regimen, many patients do not take their medications as prescribed. Non-adherence often leads to morbidity and to higher health care costs. The objective of the study was to assess patient characteristics associated with medication adherence across eight diseases. Design Retrospective data from a repository within an integrated health system was used to identify patients ≥18 years of age with ICD-9-CM codes for primary or secondary diagnoses for any of eight conditions (depression, hypertension, hyperlipidemia, diabetes, asthma or chronic obstructive pulmonary disease, multiple sclerosis, cancer, or osteoporosis). Electronic pharmacy data was then obtained for 128 medications used for treatment. Methods Medication possession ratios (MPR) were calculated for those with one condition and one drug (n=15,334) and then for the total population having any of the eight diseases (n=31,636). The proportion of patients adherent (MPR ≥80%) was summarized by patient and living-area (census) characteristics. Bivariate associations between drug adherence and patient characteristics (age, sex, race, education, and comorbidity) were tested using contingency tables and chi-square tests. Logistic regression analysis examined predictors of adherence from patient and living area characteristics. Results Medication adherence for those with one condition was higher in males, Caucasians, older patients, and those living in areas with higher education rates and higher income. In the total population, adherence increased with lower comorbidity and increased number of medications. Substantial variation in adherence was found by condition with the lowest adherence for diabetes (51%) and asthma (33%). Conclusions The expectation of high adherence due to a covered pharmacy benefit, and to enhanced medication access did not hold. Differences in medication adherence were found across condition and by

  14. Direct tabu search algorithm for the fiber Bragg grating distributed strain sensing

    NASA Astrophysics Data System (ADS)

    Karim, F.; Seddiki, O.

    2010-09-01

    A direct tabu search (DTS) algorithm used for determining the strain profile along a fiber Bragg grating (FBG) from its reflection spectrum has been demonstrated. By combining the transfer matrix method (TMM) for calculating the reflection spectrum of an FBG and the DTS method, we obtain a new method for the distributed sensing. Direct search based strategies are used to direct a tabu search. These strategies are based on a new pattern search procedure called an adaptive pattern search (APS). In addition, the well-known Nelder-Mead (NME) algorithm is used as a local search method in the final stage of the optimization process. The numerical simulations show good agreement between the original and the reconstructed strain profiles.

  15. Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG

    PubMed Central

    Xu, Jian; Yang, Dexing; Qin, Chuan; Jiang, Yajun; Sheng, Leixiang; Jia, Xiangyun; Bai, Yang; Shen, Xiaohong; Wang, Haiyan; Deng, Xin; Xu, Liangbin; Jiang, Shiquan

    2015-01-01

    To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the “HYSY-981” ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results. PMID:26610517

  16. FBG Sensor for Contact Level Monitoring and Prediction of Perforation in Cardiac Ablation

    PubMed Central

    Ho, Siu Chun Michael; Razavi, Mehdi; Nazeri, Alireza; Song, Gangbing

    2012-01-01

    Atrial fibrillation (AF) is the most common type of arrhythmia, and is characterized by a disordered contractile activity of the atria (top chambers of the heart). A popular treatment for AF is radiofrequency (RF) ablation. In about 2.4% of cardiac RF ablation procedures, the catheter is accidently pushed through the heart wall due to the application of excessive force. Despite the various capabilities of currently available technology, there has yet to be any data establishing how cardiac perforation can be reliably predicted. Thus, two new FBG based sensor prototypes were developed to monitor contact levels and predict perforation. Two live sheep were utilized during the study. It was observed during operation that peaks appeared in rhythm with the heart rate whenever firm contact was made between the sensor and the endocardial wall. The magnitude of these peaks varied with pressure applied by the operator. Lastly, transmural perforation of the left atrial wall was characterized by a visible loading phase and a rapid signal drop-off correlating to perforation. A possible pre-perforation signal was observed for the epoxy-based sensor in the form of a slight signal reversal (12–26% of loading phase magnitude) prior to perforation (occurring over 8 s). PMID:22368507

  17. FBG-based sensorized light pipe for robotic intraocular illumination facilitates bimanual retinal microsurgery.

    PubMed

    Horise, Yuki; He, Xingchi; Gehlbach, Peter; Taylor, Russell; Iordachita, Iulian

    2015-01-01

    In retinal surgery, microsurgical instruments such as micro forceps, scissors and picks are inserted through the eye wall via sclerotomies. A handheld intraocular light source is typically used to visualize the tools during the procedure. Retinal surgery requires precise and stable tool maneuvers as the surgical targets are micro scale, fragile and critical to function. Retinal surgeons typically control an active surgical tool with one hand and an illumination source with the other. In this paper, we present a "smart" light pipe that enables true bimanual surgery via utilization of an active, robot-assisted source of targeted illumination. The novel sensorized smart light pipe measures the contact force between the sclerotomy and its own shaft, thereby accommodating the motion of the patient's eye. Forces at the point of contact with the sclera are detected by fiber Bragg grating (FBG) sensors on the light pipe. Our calibration and validation results demonstrate reliable measurement of the contact force as well as location of the sclerotomy. Preliminary experiments have been conducted to functionally evaluate robotic intraocular illumination. PMID:26736189

  18. Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG.

    PubMed

    Xu, Jian; Yang, Dexing; Qin, Chuan; Jiang, Yajun; Sheng, Leixiang; Jia, Xiangyun; Bai, Yang; Shen, Xiaohong; Wang, Haiyan; Deng, Xin; Xu, Liangbin; Jiang, Shiquan

    2015-01-01

    To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the "HYSY-981" ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results. PMID:26610517

  19. Improvement of FBG/PZT hybrid sensing system for composite materials

    NASA Astrophysics Data System (ADS)

    Komatsuzaki, Shinji; Kojima, Seiji; Hongo, Akihito; Takeda, Nobuo; Koshioka, Yasuhiro

    2008-03-01

    We have been developing a system for monitoring the health of aircraft structures made of composite materials. In this system, the Lamb waves that are generated by lead zirconium titanate PZT actuators travel through the composite material structures and are received by the embedded FBG sensors. To detect any Bragg wavelength change due to the reception of the Lamb wave, an arrayed waveguide grating (AWG) is used, which converts the Bragg wavelength change into an output power change. Since the conversion ratio is largely dependent on the initial Bragg wavelength, a temperture control was necessary for obtaining an optimum condition. However, we have developed a system that uses a denser AWG to eliminate the need for a temperature control. We suceeded in detecting 25 kHz to 1 MHz Lamb waves using our new system. We have also tried calculating the Bragg wavelength change of the obtained waveform, and confirmed that the Bragg wavelength change due to the reception of Lamb waves was less than 1 pico meter.

  20. FBG sensor for contact level monitoring and prediction of perforation in cardiac ablation.

    PubMed

    Ho, Siu Chun Michael; Razavi, Mehdi; Nazeri, Alireza; Song, Gangbing

    2012-01-01

    Atrial fibrillation (AF) is the most common type of arrhythmia, and is characterized by a disordered contractile activity of the atria (top chambers of the heart). A popular treatment for AF is radiofrequency (RF) ablation. In about 2.4% of cardiac RF ablation procedures, the catheter is accidently pushed through the heart wall due to the application of excessive force. Despite the various capabilities of currently available technology, there has yet to be any data establishing how cardiac perforation can be reliably predicted. Thus, two new FBG based sensor prototypes were developed to monitor contact levels and predict perforation. Two live sheep were utilized during the study. It was observed during operation that peaks appeared in rhythm with the heart rate whenever firm contact was made between the sensor and the endocardial wall. The magnitude of these peaks varied with pressure applied by the operator. Lastly, transmural perforation of the left atrial wall was characterized by a visible loading phase and a rapid signal drop-off correlating to perforation. A possible pre-perforation signal was observed for the epoxy-based sensor in the form of a slight signal reversal (12-26% of loading phase magnitude) prior to perforation (occurring over 8 s). PMID:22368507

  1. Ultra-weak FBG and its refractive index distribution in the drawing optical fiber.

    PubMed

    Guo, Huiyong; Liu, Fang; Yuan, Yinquan; Yu, Haihu; Yang, Minghong

    2015-02-23

    For the online writing of ultra-weak fiber Bragg gratings (FBGs) in the drawing optical fibers, the effects of the intensity profile, pulse fluctuation and pulse width of the excimer laser, as well as the transverse and longitudinal vibrations of the optical fiber have been investigated. Firstly, using Lorentz-Loren equation, Gladstone-Dale mixing rule and continuity equation, we have derived the refractive index (RI) fluctuation along the optical fiber and the RI distribution in the FBG, they are linear with the gradient of longitudinal vibration velocity. Then, we have prepared huge amounts of ultra-weak FBGs in the non-moving optical fiber and obtained their reflection spectra, the measured reflection spectra shows that the intensity profile and pulse fluctuation of the excimer laser, as well as the transverse vibration of the optical fiber are little responsible for the inconsistency of ultra-weak FBGs. Finally, the effect of the longitudinal vibration of the optical fiber on the inconsistency of ultra-weak FBGs has been discussed, and the vibration equations of the drawing optical fiber are given in the appendix. PMID:25836517

  2. Medication Adherence: A Call for Action

    PubMed Central

    Bosworth, Hayden B.; Granger, Bradi B.; Mendys, Phil; Brindis, Ralph; Burkholder, Rebecca; Czajkowski, Susan M.; Daniel, Jodi G.; Ekman, Inger; Ho, Michael; Johnson, Mimi; Kimmel, Stephen E.; Liu, Larry Z; Musaus, John; Shrank, William H.; Buono, Elizabeth Whalley; Weiss, Karen; Granger, Christopher B.

    2013-01-01

    Poor adherence to efficacious cardiovascular related medications has led to considerable morbidity, mortality, and avoidable health care costs. This paper provides results of a recent think tank meeting in which various stakeholder groups representing key experts from consumers, community health providers, the academic community, decision-making government officials (FDA, NIH, etc), and industry scientists met to evaluate the current status of medication adherence and provide recommendations for improving outcomes. Below, we review the magnitude of the problem of medication adherence, prevalence, impact, and cost. We then summarize proven effective approaches and conclude with a discussion of recommendations to address this growing and significant public health issue of medication non adherence. PMID:21884856

  3. Medication adherence among adult patients on hemodialysis.

    PubMed

    Alkatheri, Abdulmalik M; Alyousif, Sarah M; Alshabanah, Najla; Albekairy, Abdulkareem M; Alharbi, Shemylan; Alhejaili, Fayze F; Alsayyari, Abdullah A; Qandil, Abeer Ma; Qandil, Amjad M

    2014-07-01

    Medication adherence was assessed in 89 patients on hemodialysis (HD) at the King Abdul Aziz Medical City using an Arabic version of the Morisky Medication Adherence Scale (MASS-8). The results of the study revealed that 31.46% and 40.45% of the participants showed low and medium adherence, respectively, while 28.09% showed high medication adherence. Accordingly, 71.91% of the patients visiting the dialysis unit were considered medication non-adherent. While being of older age (P = 0.012), being married (P = 0.012) increased the level of adherence, being of medium level of education (P = 0.024) decreased adherence levels. On the other hand, gender, presence of a care-giver, number of members in the household and employment status seems to have no effect on the level of medication adherence. These results call upon the practitioners in HD units to develop intervention programs that can increase the level of medication adherence. PMID:24969185

  4. Family interaction and treatment adherence after stroke.

    PubMed

    Evans, R L; Bishop, D S; Matlock, A L; Stranahan, S; Smith, G G; Halar, E M

    1987-08-01

    Caregivers of 60 stroke patients were assessed five months after patient discharge from a stroke care unit to determine the relationship between family function and poststroke treatment adherence. Areas of family interaction which were significantly related to ratings of treatment adherence included problem solving, communication, and affective involvement. Better functioning families were consistently high on signs of treatment adherence. Findings suggest that families with specific dysfunction may not be as capable of helping patients comply with rehabilitation efforts as families who function more effectively. Thorough family assessment to identify which areas of family interaction are most problematic in relation to adherence issues is recommended. PMID:3619615

  5. Adherence of Streptococcus salivarius HB and HB-7 to oral surfaces and saliva-coated hydroxyapatite.

    PubMed Central

    Weerkamp, A H; McBride, B C

    1980-01-01

    We compared the binding of Streptococcus salivarius HB and the mutant HB-7 to oral surfaces in vivo. Mutant HB-7 does not aggregate with saliva nor does it bind to buccal epithelium, but it does retain its ability to coaggregate with Veillonella and Fusobacterium. At 1 h after inoculation into the oral cavity of six volunteers, significantly more S. salivarius HB than HB-7 cells were found adhering to the buccal mucosa (P < 0.05) and to a cleaned tooth surface (P < 0.01); there was no significant difference in the numbers adhering to the tongue. The ratio of HB to HB-7 on the tongue increased in samples taken 1, 3, and 9 days after inoculation. The average time required to clear the mutant HB-7 from the oral cavity was 7 days, whereas that for the parent HB was greater than 20 days, and in some cases strain HB was still present 3 months after its inoculation. A representative S. salivarius serotype II strain, designated T3, behaved similarly to mutant HB-7 with respect to its adherence to the buccal mucosa. Strain HB adhered better to hydroxyapatite treated with human saliva than mutant HB-7; both strains adhered in similar numbers to untreated hydroxyapatite. Hydroxyapatite treated with rat saliva bound less HB than hydroxyapatite treated with human saliva, corresponding to the lower aggregating activity of rat saliva. Extraction of saliva with aggregating strains of S. salivarius reduced the ability of saliva to mediate attachment of strain HB to hydroxyapatite. PMID:7439971

  6. Hybrid Raman/fiber Bragg grating sensor for distributed temperature and discrete dynamic strain measurements.

    PubMed

    Toccafondo, Iacopo; Taki, Mohammad; Signorini, Alessandro; Zaidi, Farhan; Nannipieri, Tiziano; Faralli, Stefano; Di Pasquale, Fabrizio

    2012-11-01

    We propose and experimentally demonstrate a hybrid fiber optic sensing technique that effectively combines Raman optical time domain reflectometry and in-line time-division-multiplexing for fiber Bragg grating (FBG) dynamic interrogation. The highly integrated proposed scheme employs broadband apodized low reflectivity FBGs with a single narrowband optical source and a shared receiver block, allowing for simultaneous measurements of distributed static temperature and discrete dynamic strain, over the same sensing fiber. PMID:23114320

  7. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    The study searches for interface treatment that would increase the adhesion of TiC coating to nickel- and titanium-base alloys. Rene 41 (19 wt percent Cr, 11 wt percent Mo, 3 wt percent Ti, balance Ni) and Ti-6Al-4V (6 wt percent Al, 4 wt percent V, balance Ti) are considered. Adhesion of the coatings is evaluated in pin-and disk friction tests. The coatings and interface regions are examined by X-ray photoelectron spectroscopy. Results suggest that sputtered refractory compound coatings adhere best when a mixed compound of coating and substrate metals is formed in the interfacial region. The most effective type of refractory compound interface appears to depend on both substrate and coating material. A combination of metallic interlayer deposition and mixed compound interface formation may be more effective for some substrate coating combinations than either alone.

  8. A fiber optic buckle transducer for measurement of in vitro tendon strain

    NASA Astrophysics Data System (ADS)

    Roriz, Paulo; Ramos, António; Marques, Manuel B.; Simões, José A.; Frazão, Orlando

    2015-09-01

    The purpose of the present study is to present a prototype of a fiber optic based buckle transducer suitable for measuring strain caused by stretching of a tendon. The device has an E-shape and its central arm is instrumented with a fiber Bragg grating (FBG) sensor. The tendon adjusts to the E-form in a fashion that when it is stretched the central arm bends causing a shift of the Bragg's wavelength (λB) that is proportional to the amount of strain. This prototype is presented as an alternative to conventional strain gauge (SG) buckle transducers.

  9. Tm3+-doped silica fiber laser output at 1.94μm with multi-mode FBG as cavity

    NASA Astrophysics Data System (ADS)

    Wang, Hanbin; Jing, Tao; Zhang, Yunjun

    2008-11-01

    An all-fiber LD-clad-pumped Tm-doped fiber laser was reported, and the CW maximal output power reached 24W at nearly 1.94µm. The homemade double-clad Tm3+-doped fiber had a demission of 25/250µm with the core NA 0.13 and inner-clad NA 0.46. A matched passive multi-mode FBG acted as the front cavity. The cavity was build-up by the high reflectivity FBG and fiber end Fresnel reflectivity. The all-fiber scheme was build-up by splicing the pigtail fiber, FBG fiber and Tm3+-doped fiber. Cooling by the water, the 56% high slope efficiency was achieved and threshold was 6.4W, respected to the launched pump power. When the output power was less-than 3W, the output laser was single-peak operating at 1936.4 nm with a very narrow linewidth (50 pm) laser output. Increasing the launched pump power, the output laser wavelength grew to 3~4 peaks. The multimode fiber Bragg grating (FBG) transmission spectrum was also measured with a matched 82cm Nufern Tm3+-doped fiber as fluorescent sources. With the dichroic and the FBG building up cavity, the output laser characteristics were also investigated. Because the multi-mode FBG reflectivity was not very high, both ends of the fiber laser had laser output power, and the ratio was nearly 10:1. As we know, it was the first time to report the multi-mode FBG all-fiber laser. Under this simple Tm3+-doped fiber laser scheme, we estimated that the maximal output power could reach several ten watts.

  10. 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

  11. Psychological Determinants of Adolescent Exercise Adherence.

    ERIC Educational Resources Information Center

    Douthitt, Vicki L.

    1994-01-01

    High school physical education students completed questionnaires which represented four psychological variables, and one physical activity variable (exercise adherence) in classroom setting (n=132) and in summer setting (n=110). Found Perceived Romantic Appeal predictive of male exercise adherence and Perceived Athletic Competency, Perceived…

  12. Predicting asthma exacerbations employing remotely monitored adherence.

    PubMed

    Killane, Isabelle; Sulaiman, Imran; MacHale, Elaine; Breathnach, Aoife; Taylor, Terence E; Holmes, Martin S; Reilly, Richard B; Costello, Richard W

    2016-03-01

    This Letter investigated the efficacy of a decision-support system, designed for respiratory medicine, at predicting asthma exacerbations in a multi-site longitudinal randomised control trial. Adherence to inhaler medication was acquired over 3 months from patients with asthma employing a dose counter and a remote monitoring adherence device which recorded participant's inhaler use: n = 184 (23,656 audio files), 61% women, age (mean ± sd) 49.3 ± 16.4. Data on occurrence of exacerbations was collected at three clinical visits, 1 month apart. The relative risk of an asthma exacerbation for those with good and poor adherence was examined employing a univariate and multivariate modified Poisson regression approach; adjusting for age, gender and body mass index. For all months dose counter adherence was significantly (p < 0.01) higher than remote monitoring adherence. Overall, those with poor adherence had a 1.38 ± 0.34 and 1.42 ± 0.39 (remotely monitored) and 1.25 ± 0.32 and 1.18 ± 0.31 (dose counter) higher relative risk of an exacerbation in model 1 and model 2, respectively. However, this was not found to be statistically significantly different. Remotely monitored adherence holds important clinical information and future research should focus on refining adherence and exacerbation measures. Decision-support systems based on remote monitoring may enhance patient-physician communication, possibly reducing preventable adverse events. PMID:27222733

  13. A Review of Treatment Adherence Measurement Methods

    ERIC Educational Resources Information Center

    Schoenwald, Sonja K.; Garland, Ann F.

    2013-01-01

    Fidelity measurement is critical for testing the effectiveness and implementation in practice of psychosocial interventions. Adherence is a critical component of fidelity. The purposes of this review were to catalogue adherence measurement methods and assess existing evidence for the valid and reliable use of the scores that they generate and the…

  14. Experimental evidence for the role of lipids in adherence of Candida spp. to human buccal epithelial cells.

    PubMed Central

    Ghannoum, M A; Burns, G R; Elteen, K A; Radwan, S S

    1986-01-01

    Lipids extracted from Candida albicans and C. tropicalis, but not from the weakly adherent C. pseudotropicalis, significantly blocked in vitro adherence of the respective yeast cells to buccal epithelial cells. The percentage of reduction from control values ranged between 16.4 and 42.1%, depending on the species, the strain, and the solvent used for lipid extraction. The constituent lipid classes of both the acetone and chloroform-methanol extracts of C. albicans ATCC 10231 were qualitatively and quantitatively analyzed. The individual classes were isolated by preparative thin-layer chromatography and then tested for their effects on the adherence of this strain to buccal epithelial cells. Individual phospholipids, sterols, and steryl esters blocked adherence significantly (between 15.5 and 55.7% reduction). Triacylglycerols and free fatty acids showed no effect whatsoever. The same results were obtained when standard lipid samples were investigated. Images PMID:3759234

  15. Recent advances in adherence and invasion of pathogenic Escherichia coli

    PubMed Central

    Kalita, Anjana; Hu, Jia; Torres, Alfredo G.

    2014-01-01

    Purpose of review Colonization of the host epithelia by pathogenic Escherichia coli is influenced by the ability of the bacteria to interact with host surfaces. Because the initial step of an E. coli infection is to adhere, invade, and persist within host cells, some strategies used by intestinal and extra-intestinal E. coli to infect host cell are presented. Recent findings This review highlights recent progress understanding how extra-intestinal pathogenic E. coli strains express specific adhesins/invasins that allow colonization of the urinary tract or the meninges, while intestinal E. coli strains are able to colonize different regions of the intestinal tract using other specialized adhesins/invasins. Finally, evaluation of, different diets and environmental conditions regulating the colonization of these pathogens is discussed. Summary Discovery of new interactions between pathogenic E. coli and the host epithelial cells unravels the need of more mechanistic studies that can provide new clues in how to combat these infections. PMID:25023740

  16. Adherence to Antiretroviral Therapy and Virologic Failure

    PubMed Central

    Bezabhe, Woldesellassie M.; Chalmers, Leanne; Bereznicki, Luke R.; Peterson, Gregory M.

    2016-01-01

    Abstract The often cited need to achieve ≥95% (nearly perfect) adherence to antiretroviral therapy (ART) for successful virologic outcomes in HIV may present a barrier to initiation of therapy in the early stages of HIV. This meta-analysis synthesized 43 studies (27,905 participants) performed across >26 countries, to determine the relationship between cut-off point for optimal adherence to ART and virologic outcomes. Meta-analysis was performed using a random-effect model to calculate pooled odds ratios with corresponding 95% confidence intervals. The mean rate of patients reporting optimal adherence was 63.4%. Compared with suboptimal adherence, optimal adherence was associated with a lower risk of virologic failure (0.34; 95% CI: 0.26–0.44). There were no significant differences in the pooled odds ratios among different optimal adherence thresholds (≥98–100%, ≥95%, ≥80–90%). Study design (randomized controlled trial vs observational study) (regression coefficient 0.74, 95% CI: 0.04–1.43, P < 0.05) and study region (developing vs developed countries; regression coefficient 0.56, 95% CI: 0.01–1.12, P < 0.05) remained as independent predictors of between-study heterogeneity, with more patients with optimal adherence from developing countries or randomized controlled trials experiencing virologic failure. The threshold for optimal adherence to achieve better virologic outcomes appears to be wider than the commonly used cut-off point (≥95% adherence). The cut-off point for optimal adherence could be redefined to a slightly lower level to encourage the prescribing ART at an early stage of HIV infection. PMID:27082595

  17. A Brief Adherence Intervention that Improved Glycemic Control: Mediation by Patterns of Adherence

    PubMed Central

    de Vries McClintock, Heather F.; Morales, Knashawn H.; Small, Dylan S.; Bogner, Hillary R.

    2014-01-01

    This study examined whether longitudinal adherence profiles mediated the relationship between a brief adherence intervention and glycemic control among patients with Type 2 diabetes. Adherence was assessed using the Medication Event Monitoring System (MEMS). Longitudinal analysis via growth curve mixture modeling was carried out to classify patients according to patterns of adherence to oral hypoglycemic agents. Hemoglobin A1c (HbA1c) assays were used to measure glycemic control as the clinical outcome. Across the whole sample, longitudinal adherence profiles mediated 35.2% (13.2%, 81.0%) of the effect of a brief adherence intervention on glycemic control (from odds ratio (OR) = 8.48, 95% CI (3.24, 22.2) to 4.00, 95% CI (1.34, 11.93)). Our results suggest that patients in the intervention had better glycemic control largely due to their greater likelihood of adherence to oral hypoglycemic agents. PMID:24913600

  18. Artifacts in dilution pharmacokinetic models caused by adherent bacteria.

    PubMed Central

    Haag, R; Lexa, P; Werkhäuser, I

    1986-01-01

    Liquid cultures of a Pseudomonas aeruginosa strain in Mueller-Hinton broth diluted at rates higher than the bacterial growth rate showed the expected decrease in CFU only for 1 to 2 h. Later the CFU started to increase. This phenomenon can be explained by a hypothesis that assumes that the bacteria multiply in two different compartments. From the first compartment, which comprises bacteria homogeneously distributed in the broth, cells are eliminated at a rate that is dependent on the dilution and growth rates. Concomitantly, the second compartment is formed as a nondilutable adherent population on the surface of the culture vessel. Eventually, only cells stemming from that population appeared in the medium and were subsequently diluted. This hypothesis can be described mathematically by a linear combination of two exponential functions. The calculated values fit the experimental data well. Because similar CFU versus time curves were also found with other strains, care should be taken in interpreting results of experiments performed in liquid cultures and evaluated in terms of CFU. One should bear in mind that within a liquid culture an adherent population may exist, which differs in size according to selective influences (dilution, addition of antibiotics, etc.). This may give rise to artificial and unexpected results. PMID:3089140

  19. In vitro adherence of Staphylococcus pseudintermedius to canine corneocytes is influenced by colonization status of corneocyte donors

    PubMed Central

    2013-01-01

    The current knowledge of in vitro adherence of Staphylococcus pseudintermedius to canine corneocytes is limited to comparative analyses between strains, staphylococcal species or corneocytes collected from different breeds, body sites and hosts. However, the role played by colonization status of corneocyte donors remains unknown. The aim of this study was to evaluate the adherence properties of commensal S. pseudintermedius strains to corneocytes collected from dogs with different colonization status. For this purpose, corneocytes were collected from five dogs that were classified as persistently colonized (D1 and D2), intermittently colonized (D3 and D4) or non-colonized (D5) on the basis of the results of a previous longitudinal study. Adherence to corneocytes originating from each of the five dogs was assessed by an in vitro adhesion assay using four genetically unrelated strains isolated from the colonized dogs (S1 to S4). Irrespective of their host of origin, all strains adhered significantly better to corneocytes from D1 and D2 than to corneocytes from D3, D4 and D5 (P < 0.0001). The mean count of cells adhering to corneocytes from persistently colonized dogs was on average three times higher than the mean count using corneocytes from the other dogs. A significant difference between strains was only observed for one strain-corneocyte combination (S2-D4), indicating that S. pseudintermedius adherence to corneocytes is driven by host factors and only marginally influenced by strain factors. This finding has important implications for understanding and preventing S. pseudintermedius skin colonization and infection. PMID:23834238

  20. Fluorescence assay for the detection of adherent Candida yeasts to target cells in microtest plates.

    PubMed

    Borg-von Zepelin, M; Wagner, T

    1995-01-01

    We describe an assay based on photometric analysis for the measurement of adherence of Candida species to epithelial target cells (Vero cell line). Adherent Candida cells were detected by staining the cells with the fluorescent dye Calcofluor white (CFW), which binds to chitin and glucan in the yeasts. The tests were performed on microtest plates, which were analysed automatically by fluorescence plate readers. The assay is based on the following steps: (i) coating of the microtest plates with target cells (e.g. Vero cells); (ii) infection with Candida: (iii) staining of Candida with CFW; (iv) rinsing to remove non-adherent Candida cells and unbound dye; (v) detection of adherent fluorescent Candida cells. The test was able to detect 4 x 10(4) cells ml-1. The standard deviation was +/- 8%. Day-to-day variation was +/- 10% at most. The adherence of strains of different Candida species was assayed by a standard procedure. The results confirmed the order of adherence, with C. albicans ranking first, followed by C. tropicalis, C. parapsilosis and C. glabrata. PMID:8569807

  1. Portrait of Candida albicans Adherence Regulators

    PubMed Central

    Finkel, Jonathan S.; Xu, Wenjie; Huang, David; Hill, Elizabeth M.; Desai, Jigar V.; Woolford, Carol A.; Nett, Jeniel E.; Taff, Heather; Norice, Carmelle T.; Andes, David R.; Lanni, Frederick; Mitchell, Aaron P.

    2012-01-01

    Cell-substrate adherence is a fundamental property of microorganisms that enables them to exist in biofilms. Our study focuses on adherence of the fungal pathogen Candida albicans to one substrate, silicone, that is relevant to device-associated infection. We conducted a mutant screen with a quantitative flow-cell assay to identify thirty transcription factors that are required for adherence. We then combined nanoString gene expression profiling with functional analysis to elucidate relationships among these transcription factors, with two major goals: to extend our understanding of transcription factors previously known to govern adherence or biofilm formation, and to gain insight into the many transcription factors we identified that were relatively uncharacterized, particularly in the context of adherence or cell surface biogenesis. With regard to the first goal, we have discovered a role for biofilm regulator Bcr1 in adherence, and found that biofilm regulator Ace2 is a major functional target of chromatin remodeling factor Snf5. In addition, Bcr1 and Ace2 share several target genes, pointing to a new connection between them. With regard to the second goal, our findings reveal existence of a large regulatory network that connects eleven adherence regulators, the zinc-response regulator Zap1, and approximately one quarter of the predicted cell surface protein genes in this organism. This limited yet sensitive glimpse of mutant gene expression changes had thus defined one of the broadest cell surface regulatory networks in C. albicans. PMID:22359502

  2. Adherence to Antihypertensive Medications in Iranian Patients

    PubMed Central

    Behnood-Rod, Azin; Rabbanifar, Omid; Pourzargar, Pirouz; Rai, Alireza; Saadat, Zahra; Saadat, Habibollah; Moharamzad, Yashar; Morisky, Donald E.

    2016-01-01

    Introduction. Appropriate adherence to medication is still a challenging issue for hypertensive patients. We determined adherence to antihypertensive(s) and its associated factors among 280 Iranian patients. Methods. They were recruited consecutively from private and university health centers and pharmacies in four cities. The validated Persian version of the 8-item Morisky Medication Adherence Scale (MMAS-8) was administered to measure adherence. Results. Mean (±SD) overall MMAS-8 score was 5.75 (±1.88). About half of the sample (139 cases, 49.6%) showed low adherence (MMAS-8 score < 6). There was a negative linear association between the MMAS-8 score and systolic BP (r = −0.231, P < 0.001) as well as diastolic BP (r = −0.280, P < 0.001). In linear regression model, overweight/obesity (B = −0.52, P = 0.02), previous history of admission to emergency services due to hypertensive crisis (B = −0.79, P = 0.001), and getting medication directly from drugstore without refill prescription in hand (B = −0.51, P = 0.04) were factors recognized to have statistically significant association with the MMAS-8 score. Conclusion. Antihypertensive adherence was unsatisfactory. We suggest that health care providers pay special attention and make use of the aforementioned findings in their routine visits of hypertensive patients to recognize those who are vulnerable to poor adherence. PMID:27069676

  3. Adherence to Antihypertensive Medications in Iranian Patients.

    PubMed

    Behnood-Rod, Azin; Rabbanifar, Omid; Pourzargar, Pirouz; Rai, Alireza; Saadat, Zahra; Saadat, Habibollah; Moharamzad, Yashar; Morisky, Donald E

    2016-01-01

    Introduction. Appropriate adherence to medication is still a challenging issue for hypertensive patients. We determined adherence to antihypertensive(s) and its associated factors among 280 Iranian patients. Methods. They were recruited consecutively from private and university health centers and pharmacies in four cities. The validated Persian version of the 8-item Morisky Medication Adherence Scale (MMAS-8) was administered to measure adherence. Results. Mean (±SD) overall MMAS-8 score was 5.75 (±1.88). About half of the sample (139 cases, 49.6%) showed low adherence (MMAS-8 score < 6). There was a negative linear association between the MMAS-8 score and systolic BP (r = -0.231, P < 0.001) as well as diastolic BP (r = -0.280, P < 0.001). In linear regression model, overweight/obesity (B = -0.52, P = 0.02), previous history of admission to emergency services due to hypertensive crisis (B = -0.79, P = 0.001), and getting medication directly from drugstore without refill prescription in hand (B = -0.51, P = 0.04) were factors recognized to have statistically significant association with the MMAS-8 score. Conclusion. Antihypertensive adherence was unsatisfactory. We suggest that health care providers pay special attention and make use of the aforementioned findings in their routine visits of hypertensive patients to recognize those who are vulnerable to poor adherence. PMID:27069676

  4. Analysis of temperature and strain sensitivity of fiber Bragg gratings written in dual-mode highly birefringent microstructured fibers

    NASA Astrophysics Data System (ADS)

    Tenderenda, T.; Murawski, M.; Szymanski, M.; Becker, M.; Rothhardt, M.; Bartelt, H.; Mergo, P.; Poturaj, K.; Makara, M.; Skorupski, K.; Marc, P.; Jaroszewicz, L. R.; Nasilowski, T.

    2013-05-01

    Fiber Bragg gratings (FBG) are one of the most successful fiber optic technologies with very interesting perspectives for application in fiber optic sensing. It has been already reported that the possibility of its fabrication in novel microstructured fibers (MSF), creating a unique 3D structure, can significantly improve their performance and sensing properties. In this paper we present the results of FBG inscription in a dual-mode highly birefringent (HB) MSF with enhanced polarimetric strain sensitivity of the second order mode, as its mode maxima are closer to the cladding air-holes, where the strain distribution during fiber elongation is the highest. We perform an analysis and comparison of the FBG reflection and transmission characteristics, showing the effects of power coupling to cladding radiation modes. Furthermore we present the results of temperature and longitudinal strain sensitivities of the particular modes visible in the grating reflection spectrum followed by conclusions with reference to our previously reported results of polarimetric strain and temperature measurements of a similar fiber design.

  5. Effect of Temperature on Fimbrial Gene Expression and Adherence of Enteroaggregative Escherichia coli.

    PubMed

    Hinthong, Woranich; Indrawattana, Nitaya; Pitaksajjakul, Pannamthip; Pipattanaboon, Chonlatip; Kongngoen, Thida; Tharnpoophasiam, Prapin; Worakhunpiset, Suwalee

    2015-08-01

    The influence of temperature on bacterial virulence has been studied worldwide from the viewpoint of climate change and global warming. The bacterium enteroaggregative Escherichia coli (EAEC) is the causative agent of watery diarrhea and shows an increasing incidence worldwide. Its pathogenicity is associated with the virulence factors aggregative adherence fimbria type I and II (AAFI and AAFII), encoded by aggA and aafA in EAEC strains 17-2 and 042, respectively. This study focused on the effect of temperature increases from 29 °C to 40 °C on fimbrial gene expression using real-time PCR, and on its virulence using an aggregative adherence assay and biofilm formation assay. Incubation at 32 °C caused an up-regulation in both EAEC strains 17-2 and strain 042 virulence gene expression. EAEC strain 042 cultured at temperature above 32 °C showed down-regulation of aafA expression except at 38 °C. Interestingly, EAEC cultured at a high temperature showed a reduced adherence to cells and an uneven biofilm formation. These results provide evidence that increases in temperature potentially affect the virulence of pathogenic EAEC, although the response varies in each strain. PMID:26213951

  6. Imparting commercial antimicrobial dressings with low-adherence to burn wounds.

    PubMed

    Asghari, Sogol; Logsetty, Sarvesh; Liu, Song

    2016-06-01

    The objective of our study was to decrease the wound adherence of commercial silver based wound dressings by depositing a non-adherent layer. Our hypothesis was that this non-adherent layer will lower the dressing's adherence to burn wounds without compromising the antimicrobial activity or increasing the cytotoxicity. A polyacrylamide (PAM) hydrogel layer was grafted on two commercial silver antimicrobial dressings (silver nanocrystal dressing (NC) and silver plated dressing (SP)) using a proprietary technique. The grafted PAM served as the non-adherent layer. Dressing adherence was measured with a previously published in vitro gelatin model using an Instron mechanical force testing instrument. The dressings were challenged with two clinically retrieved bacterial strains (Methicillin-resistant Staphylococcus aureus (MRSA) and multidrug resistant (MDR) Pseudomonas aeruginosa) with both a disk diffusion test, and a suspension antibacterial test. The cytotoxicity of samples to human neonatal fibroblast cells was evaluated with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Both untreated dressings showed high peeling energy: 2070±453J/m(2) (NC) and 669±68J/m(2) (SP), that decreased to 158±119J/m(2) (NC) and 155±138J/m(2) (SP) with the PAM deposition. Addition of the PAM caused no significant difference in zone of inhibition (ZOI) (disk diffusion test) or antibacterial kinetics (suspension test) against both bacteria (p>0.05, n=6) in either dressing. Survival of fibroblasts was improved by the PAM grafting from 48±5% to 60±3% viable cells in the case of NC and from 55±8% to 61±4% viable cells in SP (p<0.05, n=12). It was concluded that PAM as a non-adherent layer significantly decreases the adherence of these two commercial antimicrobial dressings in an in vitro gelatin model while preserving their antimicrobial efficacy, and reducing their cytotoxicity. PMID:26847614

  7. Modeling, design, fabrication, and testing of a fiber Bragg grating strain sensor array

    NASA Astrophysics Data System (ADS)

    Abdi, Abdeq M.; Suzuki, Shigeru; Schülzgen, Axel; Kost, Alan R.

    2007-05-01

    The modeling, design, simulation, fabrication, calibration, and testing of a three-element, 15.3 cm fiber Bragg grating strain sensor array with the coherent optical frequency domain reflectometry (C-OFDR) interrogation technique are demonstrated. The fiber Bragg grating array (FBGA) is initially simulated using in-house software that incorporates transfer matrices. Compared to the previous techniques used, the transfer matrix method allows a systemwide approach to modeling the FBGA-C-OFDR system. Once designed and simulated, the FBGA system design is then imprinted into the core of a boron-germanium codoped photosensitive fiber using the phase mask technique. A fiber optic Fabry-Perot interferometric (FPI) strain gauge calibrator is then used to determine the strain gauge factor of a single fiber Bragg grating (FBG), and the results are used on the FBGA. The FPI strain gauge calibrator offers nondestructive testing of the FBG. To test the system, the FBGA is then attached to a 75 cm cantilever beam and interrogated using an incremental tunable laser. Electric strain gauges (ESGs) are then used to independently verify the strain measurements with the FBGA at various displacements of the cantilever beam. The results show that the peak strain error is 18% with respect to ESG results. In addition, good agreement is shown between the simulation and the experimental results.

  8. Strain distribution and sensitivity in fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Dadpay, C.; Sivakumar, N. R.; Mrad, N.

    2008-06-01

    Optical Fiber Bragg Gratings (FBG) sensors have seen significant development in recent years. Such sensor technology developed initially for the civil infrastructure is currently attracting the aerospace industry due to the potential versatility of this technology and its measurement capability. The structural health monitoring and the diagnostics and prognostics health management communities are excited about such development and ready to embrace such capability. Sensors reliability and accuracy, however, continue to be two parameters critical to the eventual implementation of the technology in high value targets. Such parameters can be improved by different manufacturing techniques as well as optimum grating's coating selection. This paper presents an evaluation of the mechanical behavior of the FBG strain sensors. A simulated analysis, using finite element modeling, revealed the impact of coating material selection, coating thickness selection, and bonding effect on the strain transfer loss. Results illustrate that metallic fiber coatings are more suitable for improved strain transfer than their polymeric counterparts and acrylic coatings are least effective with adhesive layer as small as possible.

  9. A highly adherent phenotype associated with virulent Bvg+-phase swine isolates of Bordetella bronchiseptica grown under modulating conditions.

    PubMed Central

    Register, K B; Ackermann, M R

    1997-01-01

    The ability of Bvg(-)-phase and Bvg(+)-phase Bordetella bronchiseptica swine isolates, grown under modulating or nonmodulating conditions, to adhere to swine ciliated nasal epithelial cells was determined. When virulent strains were cultivated at 37 degrees C in the Bvg+ phase, numerous adherent bacteria (approximately eight per cell, depending on the strain used) were observed. However, when such strains were grown under modulating conditions (23 degrees C), a significant increase in the level of attachment was seen, suggesting that B. bronchiseptica produces a Bvg-repressed adhesin under these conditions. bvg mutant strains, including an isogenic bvgS mutant, adhered minimally. Western blots indicated that two putative B. bronchiseptica adhesins, filamentous hemagglutinin and pertactin, were not detectable in cultures displaying the highly adherent phenotype. Several proteins apparent in Western blots obtained by using bacterial extracts enriched in outer membrane proteins derived from B. bronchiseptica grown at 23 degrees C were not present in similar extracts prepared from an isogenic bvgS mutant grown at 23 degrees C or from the parent strain grown at 37 degrees C. Adherence of bacteria cultivated at 23 degrees C was almost completely abolished by pretreatment of organisms at 60 degrees C; adherence was reduced by 57% when bacteria were pretreated with pronase E. Temperature shift experiments revealed that the heightened level of adhesion that occurs following growth at 23 degrees C was maintained for up to 18 h when bacteria were subsequently incubated at 37 degrees C. We propose that a Bvg-repressed adhesin, expressed only by modulated bvg+ strains of B. bronchiseptica, may play a key role in the initial colonization of naturally infected swine. PMID:9393829

  10. Oral anticancer agent medication adherence by outpatients.

    PubMed

    Kimura, Michio; Usami, Eiseki; Iwai, Mina; Nakao, Toshiya; Yoshimura, Tomoaki; Mori, Hiromi; Sugiyama, Tadashi; Teramachi, Hitomi

    2014-11-01

    In the present study, medication adherence and factors affecting adherence were examined in patients taking oral anticancer agents. In June 2013, 172 outpatients who had been prescribed oral anticancer agents by Ogaki Municipal Hospital (Ogaki, Gifu, Japan) completed a questionnaire survey, with answers rated on a five-point Likert scale. The factors that affect medication adherence were evaluated using a customer satisfaction (CS) analysis. For patients with good and insufficient adherence to medication, the median ages were 66 years (range, 21-85 years) and 73 years (range, 30-90 years), respectively (P=0.0004), while the median dosing time was 131 days (range, 3-3,585 days) and 219 days (24-3,465 days), respectively (P=0.0447). In 36.0% (62 out of 172) of the cases, there was insufficient medication adherence; 64.5% of those cases (40 out of 62) showed good medication compliance (4-5 point rating score). However, these patients did not fully understand the effects or side-effects of the drugs, giving a score of three points or less. The percentage of patients with good medication compliance was 87.2% (150 out of 172). Through the CS analysis, three items, the interest in the drug, the desire to consult about the drug and the condition of the patient, were extracted as items for improvement. Overall, the medication compliance of the patients taking the oral anticancer agents was good, but the medication adherence was insufficient. To improve medication adherence, a better understanding of the effectiveness and necessity of drugs and their side-effects is required. In addition, the interest of patients in their medication should be encouraged and intervention should be tailored to the condition of the patient. These steps should lead to improved medication adherence. PMID:25295117

  11. Oral anticancer agent medication adherence by outpatients

    PubMed Central

    KIMURA, MICHIO; USAMI, EISEKI; IWAI, MINA; NAKAO, TOSHIYA; YOSHIMURA, TOMOAKI; MORI, HIROMI; SUGIYAMA, TADASHI; TERAMACHI, HITOMI

    2014-01-01

    In the present study, medication adherence and factors affecting adherence were examined in patients taking oral anticancer agents. In June 2013, 172 outpatients who had been prescribed oral anticancer agents by Ogaki Municipal Hospital (Ogaki, Gifu, Japan) completed a questionnaire survey, with answers rated on a five-point Likert scale. The factors that affect medication adherence were evaluated using a customer satisfaction (CS) analysis. For patients with good and insufficient adherence to medication, the median ages were 66 years (range, 21–85 years) and 73 years (range, 30–90 years), respectively (P=0.0004), while the median dosing time was 131 days (range, 3–3,585 days) and 219 days (24–3,465 days), respectively (P=0.0447). In 36.0% (62 out of 172) of the cases, there was insufficient medication adherence; 64.5% of those cases (40 out of 62) showed good medication compliance (4–5 point rating score). However, these patients did not fully understand the effects or side-effects of the drugs, giving a score of three points or less. The percentage of patients with good medication compliance was 87.2% (150 out of 172). Through the CS analysis, three items, the interest in the drug, the desire to consult about the drug and the condition of the patient, were extracted as items for improvement. Overall, the medication compliance of the patients taking the oral anticancer agents was good, but the medication adherence was insufficient. To improve medication adherence, a better understanding of the effectiveness and necessity of drugs and their side-effects is required. In addition, the interest of patients in their medication should be encouraged and intervention should be tailored to the condition of the patient. These steps should lead to improved medication adherence. PMID:25295117

  12. Bayesian population modeling of drug dosing adherence.

    PubMed

    Fellows, Kelly; Stoneking, Colin J; Ramanathan, Murali

    2015-10-01

    Adherence is a frequent contributing factor to variations in drug concentrations and efficacy. The purpose of this work was to develop an integrated population model to describe variation in adherence, dose-timing deviations, overdosing and persistence to dosing regimens. The hybrid Markov chain-von Mises method for modeling adherence in individual subjects was extended to the population setting using a Bayesian approach. Four integrated population models for overall adherence, the two-state Markov chain transition parameters, dose-timing deviations, overdosing and persistence were formulated and critically compared. The Markov chain-Monte Carlo algorithm was used for identifying distribution parameters and for simulations. The model was challenged with medication event monitoring system data for 207 hypertension patients. The four Bayesian models demonstrated good mixing and convergence characteristics. The distributions of adherence, dose-timing deviations, overdosing and persistence were markedly non-normal and diverse. The models varied in complexity and the method used to incorporate inter-dependence with the preceding dose in the two-state Markov chain. The model that incorporated a cooperativity term for inter-dependence and a hyperbolic parameterization of the transition matrix probabilities was identified as the preferred model over the alternatives. The simulated probability densities from the model satisfactorily fit the observed probability distributions of adherence, dose-timing deviations, overdosing and persistence parameters in the sample patients. The model also adequately described the median and observed quartiles for these parameters. The Bayesian model for adherence provides a parsimonious, yet integrated, description of adherence in populations. It may find potential applications in clinical trial simulations and pharmacokinetic-pharmacodynamic modeling. PMID:26319548

  13. 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

    2016-02-01

    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. PMID:26906822

  14. One year of FBG-based thermo-hygrometers in operation in the CMS experiment at CERN

    NASA Astrophysics Data System (ADS)

    Berruti, Gaia Maria; Petagna, Paolo; Buontempo, Salvatore; Makovec, Alajos; Szillasi, Zoltan; Beni, Noemi; Consales, Marco; Cusano, Andrea

    2016-03-01

    In this contribution we present results concerning the very first application of fiber optic sensors (FOSs) for relative humidity (RH) monitoring in high radiations environments. After a few years of investigations at CERN in Geneva, since December 2013 our multidisciplinary research group has successfully installed 72 thermo-hygrometers based on Fiber Bragg Grating (FBG) technology, organized in multi-points arrays, in cold areas of the Tracker Bulkhead of the Compact Muon Solenoid (CMS) experiment, where hundreds of electrical connectors are housed and thousands of services, including many cold pipes, cross the volumes through them. In such a complicated environment, a constant hygrometric monitoring is vital, in order to avoid dangerous phenomena of condensation. The collected results in the last year of operation of the proposed sensors are effective and reliable, with temperature, relative humidity and dew point temperature measurements from the FBG-based devices in full agreement with the readings of conventional sensors, temporarily present in the detector. However, experience in operation has shown some limitations of this technology, which are fully detailed in the last section of the paper.

  15. Separation of FBG wavelength mixed caused by temperature and vibration based on improved Fast-ICA and self-adapting

    NASA Astrophysics Data System (ADS)

    Jiang, Shanchao; Wang, Jing; Sui, Qingmei; Ye, Qinglin; Cao, Yuqiang; Jia, Lei

    2015-03-01

    The purpose of conventional techniques for multiplexing fiber Bragg gratings (FBGs) is that each FBG has its own wavelength or unique intensity of reflected light. The cost pf per channel is at least of a few hundred dollars. All these limit the FBG points increasing at fiber measuring system. Based on improved Fast-ICA and self-adapting, this paper focuses on the separation of two same wavelength FBGs mixing model caused by temperature and vibration. Simulation experiment is carried out based on the initial wavelengths of two FBGs are both 1550.515nm and the temperature fluctuation range is 0-0.5°C and amplitude and frequency of exterior vibration are 0.01nm and 10Hz. Simulation data show that the separation steps consume 1.3884s and mean and mean square of absolute errors between the original and separated signals are 8.11·10-9, -5.83·10-12, and 2.57·10-6, 2.42·10-9, correspondingly. Therefore, through using this separation method, two same wavelength FBGs could achieve simultaneously measurement of temperature and vibration at one channel. This could double measuring points of fiber detection system, effectively.

  16. Performance of a movable flexible pipe-encapsulated FBG sensor developed for shape monitoring of multi-layered pavement structure

    NASA Astrophysics Data System (ADS)

    Wang, Huaping; Liu, Wanqiu; Zhou, Zhi

    2014-03-01

    The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.

  17. All-fiber Tm-doped double-clad fiber laser with multi-mode FBG as cavity

    NASA Astrophysics Data System (ADS)

    Zhang, Y. J.; Yao, B. Q.; Song, S. F.; Ju, Y. L.

    2009-05-01

    An all-fiber LD-clad-pumped Tm-doped fiber laser was reported, and the CW maximal output power reached 24 W at nearly 1.94 μm. The double-clad Tm-doped fiber had a demission of 25/250 μm with the core NA 0.1 and inner-clad NA 0.46. A matched passive multi-mode FBG acted as the front cavity. Cooling by the water, the 56% high slope efficiency was achieved and threshold was 6.4 W, respected to the launched pump power. At the low power pump, the fiber laser spectrum had only one peak at 1.936 μm. Increasing the launched pump power, the output laser wavelength grew to 3-4 peaks. Because the multi-mode FBG reflectivity was not very high, both ends of the fiber laser had laser output power, and the ratio was nearly 10:1.

  18. Microbicide clinical trial adherence: insights for introduction.

    PubMed

    Woodsong, Cynthia; MacQueen, Kathleen; Amico, K Rivet; Friedland, Barbara; Gafos, Mitzy; Mansoor, Leila; Tolley, Elizabether; McCormack, Sheena

    2013-01-01

    After two decades of microbicide clinical trials it remains uncertain if vaginally- delivered products will be clearly shown to reduce the risk of HIV infection in women and girls. Furthermore, a microbicide product with demonstrated clinical efficacy must be used correctly and consistently if it is to prevent infection. Information on adherence that can be gleaned from microbicide trials is relevant for future microbicide safety and efficacy trials, pre-licensure implementation trials, Phase IV post-marketing research, and microbicide introduction and delivery. Drawing primarily from data and experience that has emerged from the large-scale microbicide efficacy trials completed to-date, the paper identifies six broad areas of adherence lessons learned: (1) Adherence measurement in clinical trials, (2) Comprehension of use instructions/Instructions for use, (3) Unknown efficacy and its effect on adherence/Messages regarding effectiveness, (4) Partner influence on use, (5) Retention and continuation and (6) Generalizability of trial participants' adherence behavior. Each is discussed, with examples provided from microbicide trials. For each of these adherence topics, recommendations are provided for using trial findings to prepare for future microbicide safety and efficacy trials, Phase IV post-marketing research, and microbicide introduction and delivery programs. PMID:23561044

  19. Patient Education and Adherence to Aerosol Therapy.

    PubMed

    Ari, Arzu

    2015-06-01

    Nonadherence to prescribed medications results in disease instability and poor clinical control, with increases in hospital admissions, emergency room visits, school/work absenteeism, morbidity, and mortality. Poor patient adherence to therapy can be due to lack of cognition, competence, or contrivance. Patients who have not been trained or fail to understand use of drug and device combinations (cognition) often do not have the ability to use an aerosol device correctly (competence). Many patients have the competence to use the device correctly and know why they should use the device in the way they were taught; however, they still contrive to use it in an ineffective and suboptimal manner that reduces its efficiency and effectiveness. Ensuring effective aerosol therapy and optimizing its role in disease management involve not only delivery of aerosolized medications to the lungs, but also understanding why, when, and how to use the medications, competence to use the device, motivation to adhere to therapy, and not contriving to use the device in a way that will prevent effective drug delivery. This paper explains some of the problems with patient education and adherence to aerosol therapy and suggests strategies to evaluate, monitor, and improve patient adherence effectively in primary care. Factors affecting patient adherence to prescribed medications, effective educational interventions, and strategies to promote patient adherence to aerosol therapy are also discussed. PMID:26070585

  20. Optomechanical behavior of embedded fiber Bragg grating strain sensors

    NASA Astrophysics Data System (ADS)

    Mastro, Stephen A.

    2005-11-01

    Fiber Bragg gratings (FBGs) can provide extremely sensitive strain measurements for various materials and structures. The main functionality of the Bragg grating is along the fiber's main axis, where changes in the grating's spacing can be converted into strain measurements. Previous work from a number of researchers has identified bifurcation and broadening of the Bragg signal under transverse loading. The work presented in this thesis highlights efforts to relate transverse loading to changes in index of refraction in the fiber core cross section, and then ultimately to predicted changes in Bragg signals. The background of FBGs, their application, manufacturing, and operation is outlined. In addition, background on the general concept of photoelasticity, the relationship of stress and index of refraction, in glass materials is presented. A theoretical analysis was performed for uncoated silica fiber to calculate the stresses within an optical fiber core under transverse loading. The transverse loading profile ranged from pure diametric point loading to a more distributed profile. The stresses calculated were translated into changes of index of refraction and FBG signal values. The analysis was then simulated utilizing a numerical model, calculating stress, change of index of refraction, and change in FBG signal with various transverse loading profiles. In addition to an uncoated fiber, a polymer coated fiber system was analyzed. The model was verified by performing a laboratory experiment where FBGs were loaded transversely and their signal monitored. A special loading rig was designed and fabricated to impart transverse loading to the fiber while monitoring the compression load and deflection of the loading plates. The laboratory experienced showed reasonable agreement with the numerical model. The data show that side loading of the FBG caused a bifurcation of the signal, and that this effect can be predicted by the theoretical model. The modeling work completed

  1. Fiber Bragg Gratings, IT techniques and strain gauge validation for strain calculation on aged metal specimens.

    PubMed

    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

  2. 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

  3. Simultaneous measurement of dynamic displacement and strain in a single fiber using coarse wavelength-division multiplexing and fiber Bragg-grating filter-based sensing system.

    PubMed

    Chuang, Kuo-Chih; Ma, Chien-Ching; Wang, Hwa-Chun

    2016-03-20

    Displacement and strain, two of the most important physical quantities in experimental solid mechanics, are seldomly measured simultaneously in a single experimental configuration. In order to provide and improve corresponding sensing techniques, an experimental setup system for simultaneous measurement of dynamic displacement and strain on a flexible cantilever beam using two fiber Bragg gratings (FBGs) in a single fiber is proposed. To realize high-speed multiplexing and demodulation, a configuration incorporating a coarse wavelength-division multiplexing (CWDM) technique and an FBG transmission filter is implemented. The cantilever beam is subjected to steel-ball impact from which the dynamic multipoint displacement/strain sensing performances of the CWDM and FBG filter-based sensing system are demonstrated. Experimental results in temporal and frequency domain are compared with those obtained by the finite element method (FEM) predictions based on identification of the impact-loading history. A noncontact Fotonic displacement sensor and a polyvinylidene-fluoride film (PVDF) strain sensor are also used for comparison. With transient and resonant frequency simulations conducted by the FEM, loading effects of the sensing system are examined. The results obtained in this study indicate that the proposed CWDM and FBG filter-based sensing system is capable of performing simultaneous multipoint displacement/strain measurements in a single fiber with large bandwidth, high sensitivity, and low intensity loss. PMID:27140584

  4. Acanthamoeba adherence to contact lenses, removal by rinsing procedures, and survival to some ophthalmic products.

    PubMed

    Cancrini, G; Iori, A; Mancino, R

    1998-09-01

    Unworn soft and rigid gas-permeable contact lenses were inoculated with an Acanthamoeba keratitis strain to study the protozoon's ability to adhere. Furthermore, the efficacy of the rinsing in saline on acanthamoeba removal was evaluated, as well as the amebicidal activity of five commercial cleaning/disinfecting products: hydrogen peroxide, chlorhexidine, polyaminopropyl biguanide-poloxamine, thimerosal-polyquaternium, and thimerosal-chlorhexidine. Microscopic count of cells showed that Acanthamoeba trophozoites and cysts adhered to all types of contact lenses. A significantly greater adherence of trophozoites than cysts was recorded. The rinsing in saline using a flow-method was significantly more effective than the immersion-method, particularly in removing trophozoites from rigid gas-permeable lenses. The cleaning/disinfecting solutions tested were ineffective in removing or in affecting the viability of all Acanthamoeba trophozoites or cysts in the 17 hours allotted for the experiment. The need for a better care in mechanical and physical hygiene procedures is stressed. PMID:10376283

  5. Influence of the stiffness of testing machines on the adherence of elastomers

    SciTech Connect

    Barquins, M.

    1983-08-01

    It is shown that the introduction of the fracture mechanics concepts, such as the strain energy release rate G, to solve the problem of the adherence of elastomers, the edge of contact being seen as a crack propagating in mode I in the interface, allows one to predict the dependence of the adherence force with stiffness of testing machines. Moreover, it is shown the general equation of the kinetics of adherence proposed in 1978 in Maugis and Barquins, G - w = w(phi)(a/sub T/..nu..), where w is Dupre's work of adhesion and phi a dissipation function characteristic of the material only depending on temperature and crack speed, is confirmed whatever the stiffness of the testing machine and the instantaneous deformation imposed on the system. Experiments realized with a hemispherical glass lens in contact on a polyurethane surface verify theoretical predictions with an accuracy better than 1%.

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

    PubMed

    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; Gomes, Tânia A T

    2016-04-01

    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 fliCa nd 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 a EPEC strain 1711-4 to Caco-2 cells was drastically reduced after the treatment of Caco-2 cells with purified FliD. In addition, incubation of a EPEC 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 a EPEC 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 a EPEC to human enterocytes and disclosed the relevant structural and functional involvement of FliD in the adhesion process. PMID:26831466

  7. Role of Adherence in the Pathogenesis of Pseudomonas aeruginosa Lung Infection in Cystic Fibrosis Patients

    PubMed Central

    Woods, Donald E.; Bass, Joe A.; Johanson, W. G.; Straus, David C.

    1980-01-01

    A correlation has been demonstrated between the in vitro adherence of Pseudomonas aeruginosa to upper respiratory tract epithelium and colonization of the respiratory tract by this organism. Twenty patients with cystic fibrosis (CF) and 20 age-matched controls were examined in this study. All of the CF patients but none of the controls were colonized with P. aeruginosa at the time of study. P. aeruginosa adherence to isolated epithelial cells, as determined by an in vitro assay, was 19.1 ± 1.1 bacteria per buccal epithelial cell in the CF patients and 2.3 ± 0.3 bacteria per cell in the controls (P < 0.01). P. aeruginosa strains of the mucoid colony type adhered in significantly lower numbers to buccal epithelial cells than did strains of the rough colony type (1.8 + 0.1 versus 24.8 ± 0.9, P < 0.001). This difference might explain the common observation that the initial pseudomonas colonization of the respiratory tract of CF patients is due to organisms of the rough colony type. We have further demonstrated that increased P. aeruginosa adherence in vitro varies directly with the loss of a protease-sensitive glycoprotein, fibronectin, from the cell surface, as well as increased levels of salivary proteases in CF patients. When examined by a direct radioimmune binding assay, buccal cells from CF patients possessed only 17% of the total cell surface fibronectin present on similar cells obtained from controls. Salivary protease levels, as measured by 125I release from an 125I-labeled insoluble fibrin matrix, were increased about threefold in CF patients versus controls. Thus, colonization of the respiratory tract by P. aeruginosa in CF patients correlates well with buccal cell adherence of this organism; increased adherence is associated with decreased amounts of fibronectin on respiratory epithelial cell surfaces and increased levels of salivary proteases. PMID:7014444

  8. 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

  9. Weight loss intervention adherence and factors promoting adherence: a meta-analysis

    PubMed Central

    Lemstra, Mark; Bird, Yelena; Nwankwo, Chijioke; Rogers, Marla; Moraros, John

    2016-01-01

    Background Adhering to weight loss interventions is difficult for many people. The majority of those who are overweight or obese and attempt to lose weight are simply not successful. The objectives of this study were 1) to quantify overall adherence rates for various weight loss interventions and 2) to provide pooled estimates for factors associated with improved adherence to weight loss interventions. Methods We performed a systematic literature review and meta-analysis of all studies published between January 2004 and August 2015 that reviewed weight loss intervention adherence. Results After applying inclusion and exclusion criteria and checking the methodological quality, 27 studies were included in the meta-analysis. The overall adherence rate was 60.5% (95% confidence interval [CI] 53.6–67.2). The following three main variables were found to impact adherence: 1) supervised attendance programs had higher adherence rates than those with no supervision (rate ratio [RR] 1.65; 95% CI 1.54–1.77); 2) interventions that offered social support had higher adherence than those without social support (RR 1.29; 95% CI 1.24–1.34); and 3) dietary intervention alone had higher adherence than exercise programs alone (RR 1.27; 95% CI 1.19–1.35). Conclusion A substantial proportion of people do not adhere to weight loss interventions. Programs supervising attendance, offering social support, and focusing on dietary modification have better adherence than interventions not supervising attendance, not offering social support, and focusing exclusively on exercise. PMID:27574404

  10. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1997-01-01

    Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

  11. Trichomonas vaginalis lipophosphoglycan mutants have reduced adherence and cytotoxicity to human ectocervical cells.

    PubMed

    Bastida-Corcuera, Felix D; Okumura, Cheryl Y; Colocoussi, Angie; Johnson, Patricia J

    2005-11-01

    The extracellular human pathogen Trichomonas vaginalis is covered by a dense glycocalyx thought to play a role in host-parasite interactions. The main component of the glycocalyx is lipophosphoglycan (LPG), a polysaccharide anchored in the plasma membrane by inositol phosphoceramide. To study the role of LPG in trichomonads, we produced T. vaginalis LPG mutants by chemical mutagenesis and lectin selection and characterized them using morphological, biochemical, and functional assays. Two independently selected LPG mutants, with growth rates comparable to that of the wild-type (parent) strain, lost the ability to bind the lectins Ricinnus comunis agglutinin I (RCA120) and wheat germ agglutinin, indicating alterations in surface galactose and glucosamine residues. LPG isolated from mutants migrated faster than parent strain LPG on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting the mutants had shorter LPG molecules. Dionex high-performance anion exchange chromatography with pulsed amperometric detection analyses revealed galactosamine, glucosamine, galactose, glucose, mannose/xylose, and rhamnose as the main monosaccharides of T. vaginalis parent strain LPG. LPG from both mutants showed a reduction of galactose and glucosamine, corresponding with the reduced size of their LPG molecules and inability to bind the lectins RCA120 and wheat germ agglutinin. Mutant parasites were defective in attachment to plastic, a characteristic associated with avirulent strains of T. vaginalis. Moreover, the mutants were less adherent and less cytotoxic to human vaginal ectocervical cells in vitro than the parental strain. Finally, while parent strain LPG could inhibit the attachment of parent strain parasites to vaginal cells, LPG from either mutant could not inhibit attachment. These combined results demonstrate that T. vaginalis adherence to host cells is LPG mediated and that an altered LPG leads to reduced adherence and cytotoxicity of this parasite. PMID

  12. Trichomonas vaginalis Lipophosphoglycan Mutants Have Reduced Adherence and Cytotoxicity to Human Ectocervical Cells

    PubMed Central

    Bastida-Corcuera, Felix D.; Okumura, Cheryl Y.; Colocoussi, Angie; Johnson, Patricia J.

    2005-01-01

    The extracellular human pathogen Trichomonas vaginalis is covered by a dense glycocalyx thought to play a role in host-parasite interactions. The main component of the glycocalyx is lipophosphoglycan (LPG), a polysaccharide anchored in the plasma membrane by inositol phosphoceramide. To study the role of LPG in trichomonads, we produced T. vaginalis LPG mutants by chemical mutagenesis and lectin selection and characterized them using morphological, biochemical, and functional assays. Two independently selected LPG mutants, with growth rates comparable to that of the wild-type (parent) strain, lost the ability to bind the lectins Ricinnus comunis agglutinin I (RCA120) and wheat germ agglutinin, indicating alterations in surface galactose and glucosamine residues. LPG isolated from mutants migrated faster than parent strain LPG on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting the mutants had shorter LPG molecules. Dionex high-performance anion exchange chromatography with pulsed amperometric detection analyses revealed galactosamine, glucosamine, galactose, glucose, mannose/xylose, and rhamnose as the main monosaccharides of T. vaginalis parent strain LPG. LPG from both mutants showed a reduction of galactose and glucosamine, corresponding with the reduced size of their LPG molecules and inability to bind the lectins RCA120 and wheat germ agglutinin. Mutant parasites were defective in attachment to plastic, a characteristic associated with avirulent strains of T. vaginalis. Moreover, the mutants were less adherent and less cytotoxic to human vaginal ectocervical cells in vitro than the parental strain. Finally, while parent strain LPG could inhibit the attachment of parent strain parasites to vaginal cells, LPG from either mutant could not inhibit attachment. These combined results demonstrate that T. vaginalis adherence to host cells is LPG mediated and that an altered LPG leads to reduced adherence and cytotoxicity of this parasite. PMID

  13. The Role of Adherence and Retreatment in De Novo Emergence of MDR-TB.

    PubMed

    Cadosch, Dominique; Abel Zur Wiesch, Pia; Kouyos, Roger; Bonhoeffer, Sebastian

    2016-03-01

    Treatment failure after therapy of pulmonary tuberculosis (TB) infections is an important challenge, especially when it coincides with de novo emergence of multi-drug-resistant TB (MDR-TB). We seek to explore possible causes why MDR-TB has been found to occur much more often in patients with a history of previous treatment. We develop a mathematical model of the replication of Mycobacterium tuberculosis within a patient reflecting the compartments of macrophages, granulomas, and open cavities as well as parameterizing the effects of drugs on the pathogen dynamics in these compartments. We use this model to study the influence of patient adherence to therapy and of common retreatment regimens on treatment outcome. As expected, the simulations show that treatment success increases with increasing adherence. However, treatment occasionally fails even under perfect adherence due to interpatient variability in pharmacological parameters. The risk of generating MDR de novo is highest between 40% and 80% adherence. Importantly, our simulations highlight the double-edged effect of retreatment: On the one hand, the recommended retreatment regimen increases the overall success rate compared to re-treating with the initial regimen. On the other hand, it increases the probability to accumulate more resistant genotypes. We conclude that treatment adherence is a key factor for a positive outcome, and that screening for resistant strains is advisable after treatment failure or relapse. PMID:26967493

  14. The Role of Adherence and Retreatment in De Novo Emergence of MDR-TB

    PubMed Central

    Cadosch, Dominique; Abel zur Wiesch, Pia; Kouyos, Roger; Bonhoeffer, Sebastian

    2016-01-01

    Treatment failure after therapy of pulmonary tuberculosis (TB) infections is an important challenge, especially when it coincides with de novo emergence of multi-drug-resistant TB (MDR-TB). We seek to explore possible causes why MDR-TB has been found to occur much more often in patients with a history of previous treatment. We develop a mathematical model of the replication of Mycobacterium tuberculosis within a patient reflecting the compartments of macrophages, granulomas, and open cavities as well as parameterizing the effects of drugs on the pathogen dynamics in these compartments. We use this model to study the influence of patient adherence to therapy and of common retreatment regimens on treatment outcome. As expected, the simulations show that treatment success increases with increasing adherence. However, treatment occasionally fails even under perfect adherence due to interpatient variability in pharmacological parameters. The risk of generating MDR de novo is highest between 40% and 80% adherence. Importantly, our simulations highlight the double-edged effect of retreatment: On the one hand, the recommended retreatment regimen increases the overall success rate compared to re-treating with the initial regimen. On the other hand, it increases the probability to accumulate more resistant genotypes. We conclude that treatment adherence is a key factor for a positive outcome, and that screening for resistant strains is advisable after treatment failure or relapse. PMID:26967493

  15. 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. PMID:17900983

  16. Export of Extracellular Polysaccharides Modulates Adherence of the Cyanobacterium Synechocystis

    SciTech Connect

    Fisher, ML; Allen, R; Luo, YQ; Curtiss, R

    2013-09-10

    The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study.

  17. Pseudomonas cepacia adherence to respiratory epithelial cells is enhanced by Pseudomonas aeruginosa

    SciTech Connect

    Saiman, L.; Cacalano, G.; Prince, A. )

    1990-08-01

    Pseudomonas aeruginosa and Pseudomonas cepacia are both opportunistic pathogens of patients with cystic fibrosis. The binding characteristics of these two species were compared to determine if they use similar mechanisms to adhere to respiratory epithelial cells. P. cepacia 249 was shown to be piliated, but there was no detectable homology between P. aeruginosa pilin gene probes and P. cepacia genomic DNA. P. cepacia and P. aeruginosa did not appear to compete for epithelial receptors. In the presence of purified P. aeruginosa pili, the adherence of 35S-labeled strain 249 to respiratory epithelial monolayers was unaffected, while that of P. aeruginosa PAO1 was decreased by 55%. The binding of P. cepacia 249 and 715j was increased by 2.4-fold and 1.5-fold, respectively, in the presence of an equal inoculum of PAO1. Interbacterial agglutination contributed to the increased adherence of P. cepacia, as the binding of 249 was increased twofold in the presence of irradiated PAO1. PAO1 exoproducts had a marked effect in enhancing the ability of the P. cepacia strains to adhere to the epithelial monolayers. A PAO1 supernatant increased the binding of 249 by eightfold and that of 715j by fourfold. Thus, there appears to be a synergistic relationship between P. aeruginosa and P. cepacia in which PAO1 exoproducts modify the epithelial cell surface, exposing receptors and facilitating increased P. cepacia attachment.

  18. Differentiation of salivary agglutinin-mediated adherence and aggregation of mutans streptococci by use of monoclonal antibodies against the major surface adhesin P1.

    PubMed Central

    Brady, L J; Piacentini, D A; Crowley, P J; Oyston, P C; Bleiweis, A S

    1992-01-01

    The ability to adhere to salivary agglutinin-coated hydroxyapatite beads and to aggregate in the presence of fluid-phase salivary agglutinin was tested by using 25 isolates of mutants streptococci representing eight serotypes. Both adherence and aggregation activity correlated with expression of the Mr-185,000 cell surface antigen P1 on Streptococcus mutans serotype c, e, and f strains. In addition, it was shown that the P1 molecule itself served as the adhesin of S. mutans serotype c, since adherence was significantly inhibited by the presence of recombinant-specified Mr-150,000 P1. The ability of S. sobrinus strains to adhere or aggregate did not correlate with expression of the P1 cross-reactive antigen SpaA. There was also evidence for interaction with salivary agglutinin, as manifested by aggregation but not adherence of S. rattus serotype b, which does not express a P1 cross-reactive antigen. To understand the interaction of P1 with salivary agglutinin at the molecular level, a panel of 11 anti-P1 monoclonal antibodies was tested for inhibitory activity in adherence and aggregation inhibition assays. Overlapping, but not identical, subsets of monoclonal antibodies were found to inhibit adherence and aggregation, indicating that the interactions of P1 with salivary agglutinin which mediate these two phenomena are different. The localization of functional domains of P1 which may mediate the aggregation and adherence reactions is discussed. PMID:1541515

  19. Hemagglutination and intestinal adherence properties of clinical and environmental isolates of non-O1 Vibrio cholerae.

    PubMed Central

    Datta-Roy, K; Dasgupta, C; Ghose, A C

    1989-01-01

    Hemagglutination and intestinal adherence properties of non-O1 Vibrio cholerae were studied in vitro. No definite correlation between the cell-associated hemagglutinin titers and the intestinal adhesion indices was noted. Sugar- and glycoprotein-mediated inhibition data also indicated differences between the hemagglutination and adherence processes in respect to the receptor structures. Intestinal adherence of most V. cholerae strains could be inhibited to various extents by N-acetyl D-glucosamine. This observation provides a likely explanation for the ecological behavior of these organisms, which are known to associate themselves with chitinous (chitin:homopolymer of N-acetyl D-glucosamine) surfaces of zooplankton. The absence of any significant difference between the intestinal adherence indices of clinical and environmental isolates suggests that intestinal adhesion may be an essential but not sufficient prerequisite for colonization by and subsequent expression of pathogenicity of these microorganisms. PMID:2802613

  20. Adherence to Glycemic Monitoring in Diabetes

    PubMed Central

    Patton, Susana R.

    2015-01-01

    Glucose monitoring either by self-monitoring of blood glucose (SMBG) or continuous glucose monitoring (CGM) plays an important role in diabetes management and in reducing risk for diabetes-related complications. However, despite evidence supporting the role of glucose monitoring in better patient health outcomes, studies also reveal relatively poor adherence rates to SMBG and CGM use and numerous patient-reported barriers. Fortunately, some promising intervention strategies have been identified that promote at least short-term improvements in patients’ adherence to SMBG. These include education, problem solving, contingency management, goal setting, cognitive behavioral therapy, and motivational interviewing. Specific to CGM, interventions to promote greater use among patients are currently under way, yet one pilot study provides data suggesting better maintenance of CGM use in patients showing greater readiness for behavior change. The purpose of this review is to summarize the literature specific to glucose monitoring in patients with diabetes focusing specifically on current adherence rates, barriers to monitoring, and promising intervention strategies that may be ready to deploy now in the clinic setting to promote greater patient adherence to glucose monitoring. Yet, to continue to help patients with diabetes adhere to glucose monitoring, future research is needed to identify the treatment strategies and the intervention schedules that most likely lead to long-term maintenance of optimal glycemic monitoring levels. PMID:25591853

  1. MEMS Graphene Strain Sensor

    NASA Astrophysics Data System (ADS)

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  2. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  3. Transient dynamic distributed strain sensing using photonic crystal fibres

    NASA Astrophysics Data System (ADS)

    Samad, Shafeek A.; Hegde, G. M.; Roy Mahapatra, D.; Hanagud, S.

    2014-02-01

    A technique to determine the strain field in one-dimensional (1D) photonic crystal (PC) involving high strain rate, high temperature around shock or ballistic impact is proposed. Transient strain sensing is important in aerospace and other structural health monitoring (SHM) applications. We consider a MEMS based smart sensor design with photonic crystal integrated on a silicon substrate for dynamic strain correlation. Deeply etched silicon rib waveguides with distributed Bragg reflectors are suitable candidates for miniaturization of sensing elements, replacing the conventional FBG. Main objective here is to investigate the effect of non-uniform strain localization on the sensor output. Computational analysis is done to determine the static and dynamic strain sensing characteristics of the 1D photonic crystal based sensor. The structure is designed and modeled using Finite Element Method. Dynamic localization of strain field is observed. The distributed strain field is used to calculated the PC waveguide response. The sensitivity of the proposed sensor is estimated to be 0.6 pm/μɛ.

  4. Strategies to Increase Adherence through Diabetes Technology

    PubMed Central

    Gabbay, Robert A.; Durdock, Kendra

    2010-01-01

    A variety of new technologies have been developed to assist patients with self-managing their diabetes and yet hemoglobin A1c has not changed dramatically over the last decade. Although more data available from these new diabetes technologies can be helpful, it is clear that an informed, motivated, and adherent patient is the key to success. This article focuses on increasing patient adherence through the use of motivational interviewing, an evidence-based behavior change counseling technique. Specific skills of motivational interviewing may help the provider assess what the patient already knows about the technology, explore the patient's motivation for using the technology, and, finally, assess the patient's barriers, importance, and confidence in using the technology, leading to better adherence. PMID:20513334

  5. Strategies to increase adherence through diabetes technology.

    PubMed

    Gabbay, Robert A; Durdock, Kendra

    2010-05-01

    A variety of new technologies have been developed to assist patients with self-managing their diabetes and yet hemoglobin A1c has not changed dramatically over the last decade. Although more data available from these new diabetes technologies can be helpful, it is clear that an informed, motivated, and adherent patient is the key to success. This article focuses on increasing patient adherence through the use of motivational interviewing, an evidence-based behavior change counseling technique. Specific skills of motivational interviewing may help the provider assess what the patient already knows about the technology, explore the patient's motivation for using the technology, and, finally, assess the patient's barriers, importance, and confidence in using the technology, leading to better adherence. PMID:20513334

  6. Fiber-Optic Strain and Temperature Monitoring System for DUSEL

    NASA Astrophysics Data System (ADS)

    Wang, H. F.; Maclaughlin, M.; Fratta, D.; Murdoch, L. C.

    2009-12-01

    The opportunity to understand the response of rock masses to stresses deep within the earth's crust as a function of spatial and temporal scale is at the center of the geomechanics research program proposed for DUSEL. Within the 10-km3 volume of the former Homestake mine, deformations are expected from earth tides, effective stress changes caused by mine dewatering, seasonal water table changes, and new excavations as well as from long-term creep of drifts and shafts. Data from a whole-mine deformation monitoring and measurement system are integral to calibrating a mine-scale, mechanical and hydrological finite-element model of laboratory and detector space. A synergistic objective of a long-term, state-of-the-art monitoring system is to ensure shaft, tunnel, and cavern stability as well as occupant safety. Fiber-optic sensors are highly stable over long periods of time and they can be daisy-chained to significantly simplify the logistics of acquiring data from dozens of sensors. Temperature measurements over large spatial scales in fluid-saturated boreholes can delineate fluid-flow paths and can be deployed as a secondary monitoring system for ventilation and anomalous air temperatures. Two types of fiber-optic sensors are available: distributed strain and temperature (DST) and Fiber Bragg Grating (FBG). DST sensors can be installed over kilometers of distance with measurement resolutions of 1-to-10 microstrains and 0.1°C over intervals of 1-to-2 meters. FBG strain gages and displacement transducers function the same as their electrical counterparts, save for the underlying physics in that displacements are measured as a shift in the spacing of a Bragg grating embedded into the optical fiber. These systems are highly scalable as more than 50,000 points of temperature and strain measurements can be collected from a single fiber-optic cable. Other fiber-based sensors, e.g., acceleration, air pressure, and gases, are also available and can become part of a fiber

  7. Simultaneous measurement of strain and temperature by two peanut tapers with embedded fiber Bragg grating.

    PubMed

    Lv, Lingya; Wang, Sumei; Jiang, Lan; Zhang, Fei; Cao, Zhitao; Wang, Peng; Jiang, Yi; Lu, Yongfeng

    2015-12-20

    A compact optical fiber sensor for simultaneous measurement of strain and temperature is designed and experimentally investigated. The proposed sensor consists of a two-peanut-taper Mach-Zehnder interferometer (MZI) and in-line embedded fiber Bragg grating (FBG). The sensor at a length of 35 mm presents strain sensitivities 1.07  pm/με and 0.891  pm/με, the temperature sensitivities are 55.35  pm/°C and 10.85  pm/°C, for MZI and FBG, respectively. Through tapering the center of the sensor by a fusion splicer, the strain sensitivity of the MZI is improved to 1.93  pm/με. The resolutions for strain and temperature measurement are ±3.104  με and ±0.194°C with the wavelength resolution of 5 pm. The experimental results show that the sensor is able to simultaneously measure strain and temperature by sensitivity matrix with advantages such as simple structure, compact size, ease of fabrication, low cost, etc. PMID:26837035

  8. Polarization dependence of the strain sensitivity of fiber Bragg gratings inscribed in highly birefringent optical fibers

    NASA Astrophysics Data System (ADS)

    Singh, Paul; Jülich, Florian; Roths, Johannes

    2012-04-01

    It can be expected that the range of applications for FBG-based strain and temperature sensors would expand if the accuracy of this sensor technique was improved. In this study, polarization effects of FBG sensors, which contribute significantly to the measurement uncertainty of this technique, were investigated. Therefore, FBGs were inscribed into highly birefringent optical fibers. These sensor elements were attached to a specimen with defined orientations of the fiber's slow and fast axes with regard the specimen's surface. We observed a change of the fiber's birefringence in the order of 5 10-5 as a consequence of the gluing process, that was employed to attach the fiber onto the specimen. The strain sensitivities were determined for each polarization mode and for different fiber orientations using a highly accurate strain calibration facility. It was found that in all experiments the strain sensitivity for the slow axis was significantly higher (about 0.8%) than for the fast axis. The strain sensitivity also depends on the orientation of the fiber's birefringent axes with regard to the surface of the specimen. Although the investigations were performed with FBGs inscribed into birefringent fibers, the findings are still of importance for understanding the polarization-dependant accuracy limits of FBGs in standard single-mode fibers.

  9. Assessment of hydrophobicity and roughness of stainless steel adhered by an isolate of Bacillus cereus from a dairy plant

    PubMed Central

    Bernardes, Patrícia Campos; de Andrade, Nélio José; Ferreira, Sukarno Olavo; de Sá, João Paulo Natalino; Araújo, Emiliane Andrade; Delatorre, Deyse Maria Zanom; Luiz, Lívia Maria Pinheiro

    2010-01-01

    The interaction between the surface of stainless steel and Bacillus cereus was studied in terms of the characteristics of interfacial interaction determined from the measurement of the contact angle of the surface of B. cereus and stainless steel in the presence or absence of B. cereus adherence. The microtopographies and the roughness of the surface of stainless steel and stainless steel adhered by B. cereus were evaluated with the help of atomic force microscopy and perfilometry. The strain of B. cereus studied was considered hydrophilic, whereas the stainless steel was considered hydrophobic. The adhesion was not thermodynamically favorable (ΔGadhesion > 0) between the stainless steel and the strain of B. cereus studied. Thus, the interaction between them was not favored by the thermodynamic aspect of adhesion. There was no difference (p > 0.05) in the roughness of the surfaces of stainless steel adhered by B. cereus when analyzed by atomic force microscope and perfilometry. PMID:24031578

  10. Research of weapon equipments health monitoring based on FBG intelligent composite materials

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-li; Fu, Zhu-lin; Zhao, Bing; Xu, Jian-guo

    2010-10-01

    Embedding the Polymer fibers, whose limiting strain is about 10%, into the composite materials to form the intelligent materials is researched. Encapsulating polymer fibers with epoxy resin of identical elastic modulus and embedding them into the structures during the molding process. The Demodulating system based on F-P filter method is advanced to analyze the shift of wavelengths with high speed DSP TMSC3206713 as data processor. Precise PIN photoelectric cell-InGaAs-PIN-PD753, is used to transform the output of F-P filter to electricity and two high speed A/D chips ADS1610 are used to collect the outputs of PINs. C2H2 GC for dynamical wavelength demarcation is advanced for more precise metrical results. Strain and damage condition information is transferred to the master computer as the references of health monitoring of weapon equipments. The primary experiments indicate that when 2 fibers with 3 gratings on each are embedded into the material, the intensity of materials don't weaken obviously. During the molding process of high temperature and high pressure, reflected spectrum of FBGs in hot stretching environment is analyzed through Spectrum Instrument. Fibers do not be ruptured and their sensitivity of strain is well. F-P demodulating system realizes strain resolution by 2μɛ when it works at 200Hz.

  11. A Review of Treatment Adherence Measurement Methods

    PubMed Central

    Schoenwald, Sonja K.; Garland, Ann F.

    2013-01-01

    Fidelity measurement is critical for testing the effectiveness and implementation in practice of psychosocial interventions. Adherence is a critical component of fidelity. The purposes of this review were to catalogue adherence measurement methods and assess existing evidence for the valid and reliable use of scores they generate and feasibility of use in routine care settings. Method A systematic literature search identified articles published between 1980–2008 reporting studies of evidence-based psychosocial treatments for child or adult mental health problems, and including mention of adherence or fidelity assessment. Coders abstracted data on the measurement methods and clinical contexts of their use. Results 341 articles were reviewed in which 249 unique adherence measurement methods were identified. These methods assessed many treatment models, although more than half (59%) assessed Cognitive Behavioral Treatments. The measurement methods were used in studies with diverse clientele and clinicians. The majority (71.5%) of methods were observational. Information about psychometric properties was reported for 35% of the measurement methods, but adherence-outcomes relationships were reported for only ten percent. Approximately one third of the measures were used in community- based settings. Conclusions Many adherence measurement methods have been used in treatment research; however, little reliability and validity evidence exists for the use of these methods. That some methods were used in routine care settings suggests the feasibility of their use in practice; however, information about the operational details of measurement, scoring, and reporting is sorely needed to inform and evaluate strategies to embed fidelity measurement in implementation support and monitoring systems. PMID:22888981

  12. 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

  13. Hydrogen FBG sensor using Pd/Ag film with application in propulsion system fuel tank model of aerospace vehicle

    NASA Astrophysics Data System (ADS)

    Saad, Said; Hassine, Lotfi; Elfahem, Wassim

    2014-09-01

    The high efficiency hydrogen fiber Bragg grating (FBG) sensor is presented. The sensitive film was a new alliance of palladium-silver (Pd-Ag). In addition, the titanium (Ti) layer was used as the adhesive layer. The presented sensor showed the resolution of more than 60 pm/1% H2, and a fast response time of 4 s-5 s was guaranteed in the 0.1% H2-4% H2 range. Moreover, the life time of the sensor was investigated. The obtained results showed that the sensor had an enhanced life time. Furthermore, the sensor was applied in the propulsion system fuel tank model of the aerospace vehicle. The obtained results indicated that it is a prevention system against the disaster aerospace due to hydrogen leakage.

  14. [Challenges of adolescents' adherence to therapy].

    PubMed

    Brand, P L P; Kaptein, A A; Janssens, L P F; Klok, T

    2016-01-01

    Non-adherence occurs at any age, in all chronic diseases, and has a major impact on clinical outcomes. Non-adherence is primarily determined by perceptions of illness and medication beliefs. During puberty, adolescents attain independence from their parents and attach to their peers. This complicates successful self-management of chronic illness, because the adolescents avoid standing out from their peers. Discussion of barriers hindering successful self-management in adolescents can be promoted by seeing the patient alone, without the parents being present, and by acknowledging the patient's independence and responsibilities. PMID:27581866

  15. [Adherence to statins: updates and practical proposals].

    PubMed

    Bauwens, Marine; Schneider, Marie-paule; Nanchen, David

    2016-03-01

    Statins are an established treatment for dyslipidemia, because they were shown to decrease the cardiovascular risk by 25%. However, one third of patients using statins don't take them regularly. Statin intolerance is an important risk factor for nonadherence, but health literacy and lack of education regarding the cardiovascular benefits are also important triggers for poor adherence to statins. A better communication between the caregiver and his patient, by taking patient's perspectives into account could help find effective solutions. This article reviews the issue of statins adherence and suggests solutions to improve it. PMID:27089601

  16. Power-stabilized tunable narrow-band source using a VCSEL and an EDFA for FBG sensor interrogation

    NASA Astrophysics Data System (ADS)

    Mizunami, Toru; Hirose, Shuji; Yoshinaga, Takeshi; Yamamoto, Ken-ichi

    2013-09-01

    Wavelength tuning with a current of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) was studied for application to wavelength readout of fiber Bragg grating (FBG) sensors. 1.5 µm single-longitudinal-mode VCSELs with a spectral line width of 30 MHz were used. To decrease the variation in the output power with the current, saturated amplification of the VCSEL output by an erbium-doped fiber amplifier (EDFA) was proposed. In the experiment, the wavelength readout of an FBG by variation in the VCSEL current was studied first, and then amplification characteristics using a commercially available EDFA module were measured. Two VCSELs with different wavelengths and tuning ranges were used as input and compared. For a VCSEL with a wavelength tuning range of 2.5 nm, there was a threefold change in the VCSEL output power. However, the variation in the amplified output power was within ±14%. For another VCSEL with a wavelength tuning range of 3.9 nm, the variation in the amplified output power was within ±18% for variation in the VCSEL output power by 2.2 times. The power slope with respect to the wavelength was also decreased by the stabilization. Computer simulation was performed to study the wavelength shift in the measured Bragg wavelength induced by the power slope. The simulation showed that the wavelength shift can be reduced to 1/2.5-1/5 by the stabilization compared with that using a single VCSEL. Application to long-period grating sensors was also discussed.

  17. Adherence to Cardiovascular Medications: Lessons Learned and Future Directions

    PubMed Central

    Kronish, Ian M; Ye, Siqin

    2013-01-01

    Approximately 50% of patients with cardiovascular disease and/or its major risk factors have poor adherence to their prescribed medications. Finding novel methods to help patients improve their adherence to existing evidence-based cardiovascular drug therapies has enormous potential to improve health outcomes while potentially reducing health care costs. The goal of this report is to provide a review of the current understanding of adherence to cardiovascular medications from the point of view of prescribing clinicians and cardiovascular researchers. Key topics addressed include: 1) definitions of medication adherence; 2) prevalence and impact of non-adherence; 3) methods for assessing medication adherence; 4) reasons for poor adherence; and 5) approaches to improving adherence to cardiovascular medications. For each of these topics, the report seeks to identify important gaps in knowledge and opportunities for advancing the field of cardiovascular adherence research. PMID:23621969

  18. Medication adherence to oral anticancer drugs: systematic review.

    PubMed

    Huang, Wen-Chuan; Chen, Chung-Yu; Lin, Shun-Jin; Chang, Chao-Sung

    2016-04-01

    Many studies have demonstrated that non-adherence to oral anticancer drugs (OACDs) has challenged treatment efficacy. Otherwise, few validated tools exist to measure patients' adherence to medication regimen in clinical practice. To synthesize previous studies on adherence by cancer patients taking OACDs, especially in targeted therapy, a systematic search of several electronic databases was conducted. We analyzed existing scales' contents for various cancer patients and outcomes of studies assessing adherence. However, a well-validated scale designed particularly for OACD adherence is still lacking. Most adherence scales used in the studies reviewed contain items focused on measuring patients' medication-taking behavior more than their barriers to medication compliance and beliefs. However, non-adherence to OACDs is a complex phenomenon, and drug-taking barriers and patient beliefs significantly affect patients' non-adherence. To understand the key drivers and predisposing factors for non-adherence, we need to develop a well-validated, multidimensional scale. PMID:26935964

  19. Survival of Adhering Staphylococci during Exposure to a Quaternary Ammonium Compound Evaluated by Using Atomic Force Microscopy Imaging▿

    PubMed Central

    Crismaru, Mihaela; Asri, Lia A. T. W.; Loontjens, Ton J. A.; Krom, Bastiaan P.; de Vries, Joop; van der Mei, Henny C.; Busscher, Henk J.

    2011-01-01

    Effects of a quaternary ammonium compound (QAC) on the survival of adhering staphylococci on a surface were investigated using atomic force microscopy (AFM). Four strains with different minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) for the QAC were exposed to three different concentrations of the QAC in potassium phosphate buffer (0.5×, 1×, and 2× MBC) while adhering to glass. Adhering staphylococci were repeatedly imaged with AFM in the contact mode, and the cell surface was found to wrinkle upon progressive exposure to the QAC until bacteria disappeared from the substratum. Higher concentrations of QAC yielded faster wrinkling and the disappearance of bacteria during imaging. Two slime-producing staphylococcal strains survived longer on the surface than two non-slime-producing strains despite similar MICs and MBCs. All staphylococci adhering in unscanned areas remained adhering during exposure to QAC. Since MICs and MBCs did not relate to bacterial cell surface hydrophobicities and zeta potentials, survival on the surface is probably not determined by the direct interaction of QAC molecules with the cell surface. Instead, it is suggested that the pressure of the AFM tip assists the incorporation of QAC molecules in the membrane and enhances their bactericidal efficacy. In addition, the prolonged survival under pressure from slime-producing strains on a surface may point to a new protective role of slime as a stress absorber, impeding the incorporation of QAC molecules. The addition of Ca2+ ions to a QAC solution yielded longer survival of intact, adhering staphylococci, suggesting that Ca2+ ions can impede the exchange of membrane Ca2+ ions required for QAC incorporation. PMID:21876063

  20. The role of Listeria monocytogenes cell wall surface anchor protein LapB in virulence, adherence, and intracellular replication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lmof2365_2117 is a Listeria monocytogenes putative cell wall surface anchor protein with a conserved domain found in collagen binding proteins. We constructed a deletion mutation in lmof2365_2117 in serotype 4b strain F2365, evaluated its virulence, and determined its ability to adhere and invade co...

  1. Lactobacillus reuteri Inhibition of Enteropathogenic Escherichia coli Adherence to Human Intestinal Epithelium

    PubMed Central

    Walsham, Alistair D. S.; MacKenzie, Donald A.; Cook, Vivienne; Wemyss-Holden, Simon; Hews, Claire L.; Juge, Nathalie; Schüller, Stephanie

    2016-01-01

    Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrheal infant death in developing countries, and probiotic bacteria have been shown to provide health benefits in gastrointestinal infections. In this study, we have investigated the influence of the gut symbiont Lactobacillus reuteri on EPEC adherence to the human intestinal epithelium. Different host cell model systems including non-mucus-producing HT-29 and mucus-producing LS174T intestinal epithelial cell lines as well as human small intestinal biopsies were used. Adherence of L. reuteri to HT-29 cells was strain-specific, and the mucus-binding proteins CmbA and MUB increased binding to both HT-29 and LS174T cells. L. reuteri ATCC PTA 6475 and ATCC 53608 significantly inhibited EPEC binding to HT-29 but not LS174T cells. While pre-incubation of LS174T cells with ATCC PTA 6475 did not affect EPEC attaching/effacing (A/E) lesion formation, it increased the size of EPEC microcolonies. ATCC PTA 6475 and ATCC 53608 binding to the mucus layer resulted in decreased EPEC adherence to small intestinal biopsy epithelium. Our findings show that L. reuteri reduction of EPEC adhesion is strain-specific and has the potential to target either the epithelium or the mucus layer, providing further rationale for the selection of probiotic strains. PMID:26973622

  2. Lactobacillus reuteri Inhibition of Enteropathogenic Escherichia coli Adherence to Human Intestinal Epithelium.

    PubMed

    Walsham, Alistair D S; MacKenzie, Donald A; Cook, Vivienne; Wemyss-Holden, Simon; Hews, Claire L; Juge, Nathalie; Schüller, Stephanie

    2016-01-01

    Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrheal infant death in developing countries, and probiotic bacteria have been shown to provide health benefits in gastrointestinal infections. In this study, we have investigated the influence of the gut symbiont Lactobacillus reuteri on EPEC adherence to the human intestinal epithelium. Different host cell model systems including non-mucus-producing HT-29 and mucus-producing LS174T intestinal epithelial cell lines as well as human small intestinal biopsies were used. Adherence of L. reuteri to HT-29 cells was strain-specific, and the mucus-binding proteins CmbA and MUB increased binding to both HT-29 and LS174T cells. L. reuteri ATCC PTA 6475 and ATCC 53608 significantly inhibited EPEC binding to HT-29 but not LS174T cells. While pre-incubation of LS174T cells with ATCC PTA 6475 did not affect EPEC attaching/effacing (A/E) lesion formation, it increased the size of EPEC microcolonies. ATCC PTA 6475 and ATCC 53608 binding to the mucus layer resulted in decreased EPEC adherence to small intestinal biopsy epithelium. Our findings show that L. reuteri reduction of EPEC adhesion is strain-specific and has the potential to target either the epithelium or the mucus layer, providing further rationale for the selection of probiotic strains. PMID:26973622

  3. Correlates of Adherence to Varenicline Among HIV+ Smokers

    PubMed Central

    Tseng, Tuo-Yen; Gonzalez, Mirelis; Krebs, Paul; Wong, Selena; Furberg, Robert; Sherman, Scott; Schoenthaler, Antoinette; Urbina, Anthony; Cleland, Charles M.

    2015-01-01

    Introduction: Low rates of adherence to smoking cessation pharmacotherapy may limit the effectiveness of treatment. However, few studies have examined adherence in smoking cessation trials thus, there is a limited understanding of factors that influence adherence behaviors. This brief report analyzes correlates of adherence to varenicline among people living with HIV/AIDS. Methods: Study participants were recruited from three HIV care centers in New York City and enrolled in a three-arm randomized controlled pilot study in which all subjects received varenicline. At the 1-month study visit, there were no significant differences in adherence by study condition, therefore we combined treatment arms to examine correlates of adherence (n = 127). We used pill counts to assess varenicline adherence, defined as taking at least 80% of the prescribed dose. We conducted a multivariate path analysis to assess factors proposed by the information-motivation-behavioral skills model to predict adherence. Results: Only 56% of smokers were at least 80% adherent to varenicline at 1 month. Adherence-related information, self-efficacy, a college degree, and non-Hispanic white race/ethnicity were associated with increased varenicline adherence. In path analysis, information and motivation were associated with increased adherence self-efficacy, and adherence self-efficacy was associated with increased adherence, but with marginal significance. These associations with adherence were no longer significant after controlling for race/ethnicity and education. Conclusions: Further exploration of the role of a modifiable correlates of adherence, such as adherence-related information, motivation and self-efficacy is warranted. Interventions are needed that can address disparities in these and other psychosocial factors that may mediate poor medication adherence. PMID:26180221

  4. Continuous ambulatory peritoneal dialysis (CAPD) peritonitis: the effect of antibiotic on the adherence of coagulase-negative staphylococci to silicone rubber catheter material.

    PubMed

    Finch, R G; Edwards, R; Filik, R; Wilcox, M H

    1989-01-01

    Peritonitis is the major complication of continuous ambulatory peritoneal dialysis (CAPD) and is caused predominantly by coagulase-negative staphylococci (CNS). Adherence to the silicone rubber Tenckhoff catheter has been identified as one factor in the pathogenesis and persistence of these infections. We have studied the adherence of CNS from patients and controls to silicone rubber in an in vitro model to determine whether this phenomenon can be modified by antibiotics. Adherence was strong for 7/27 (26%) CAPD isolates and for 3/27 (11%) of control strains. The strongly adherent CAPD isolates, when exposed to subinhibitory concentrations of vancomycin, cefuroxime, and ciprofloxacin, showed minimal alteration in adherence with vancomycin in both broth and used dialysate, whereas cefuroxime and ciprofloxacin both significantly reduced it. These observations may have implications for drug selection and prevention of CAPD peritonitis caused by CNS. PMID:2488193

  5. E-health strategies to support adherence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adherence to healthy behaviors and self-care strategies is a concern among clinicians. E-health applications, such as the internet, personal communication devices, electronic health records and web portals, and electronic games, may be a way to provide health information in a way that is reliable, c...

  6. Adherence to Exercise and Physical Activity: Preface.

    ERIC Educational Resources Information Center

    Morgan, William P.; Dishman, Rod K.

    2001-01-01

    Introduces a collection of papers on adherence to exercise programs and physical activity from the 2000 American Academy of Kinesiology and Physical Education conference, which included research on middle school boys and girls, college men and women, and men and women in the later years, as well as on the more traditional subject of middle aged…

  7. Lactobacilli Interfere with Streptococcus pyogenes Hemolytic Activity and Adherence to Host Epithelial Cells.

    PubMed

    Saroj, Sunil D; Maudsdotter, Lisa; Tavares, Raquel; Jonsson, Ann-Beth

    2016-01-01

    Streptococcus pyogenes [Group A streptococcus (GAS)], a frequent colonizer of the respiratory tract mucosal surface, causes a variety of human diseases, ranging from pharyngitis to the life-threatening streptococcal toxic shock-like syndrome. Lactobacilli have been demonstrated to colonize the respiratory tract. In this study, we investigated the interference of lactobacilli with the virulence phenotypes of GAS. The Lactobacillus strains L. rhamnosus Kx151A1 and L. reuteri PTA-5289, but not L. salivarius LMG9477, inhibited the hemolytic activity of S. pyogenes S165. The inhibition of hemolytic activity was attributed to a decrease in the production of streptolysin S (SLS). Conditioned medium (CM) from the growth of L. rhamnosus Kx151A1 and L. reuteri PTA-5289 was sufficient to down-regulate the expression of the sag operon, encoding SLS. The Lactobacillus strains L. rhamnosus Kx151A1, L. reuteri PTA-5289, and L. salivarius LMG9477 inhibited the initial adherence of GAS to host epithelial cells. Intriguingly, competition with a combination of Lactobacillus species reduced GAS adherence to host cells most efficiently. The data suggest that an effector molecule released from certain Lactobacillus strains attenuates the production of SLS at the transcriptional level and that combinations of Lactobacillus strains may protect the pharyngeal mucosa more efficiently from the initial colonization of GAS. The effector molecules released from Lactobacillus strains affecting the virulence phenotypes of pathogens hold potential in the development of a new generation of therapeutics. PMID:27524981

  8. Lactobacilli Interfere with Streptococcus pyogenes Hemolytic Activity and Adherence to Host Epithelial Cells

    PubMed Central

    Saroj, Sunil D.; Maudsdotter, Lisa; Tavares, Raquel; Jonsson, Ann-Beth

    2016-01-01

    Streptococcus pyogenes [Group A streptococcus (GAS)], a frequent colonizer of the respiratory tract mucosal surface, causes a variety of human diseases, ranging from pharyngitis to the life-threatening streptococcal toxic shock-like syndrome. Lactobacilli have been demonstrated to colonize the respiratory tract. In this study, we investigated the interference of lactobacilli with the virulence phenotypes of GAS. The Lactobacillus strains L. rhamnosus Kx151A1 and L. reuteri PTA-5289, but not L. salivarius LMG9477, inhibited the hemolytic activity of S. pyogenes S165. The inhibition of hemolytic activity was attributed to a decrease in the production of streptolysin S (SLS). Conditioned medium (CM) from the growth of L. rhamnosus Kx151A1 and L. reuteri PTA-5289 was sufficient to down-regulate the expression of the sag operon, encoding SLS. The Lactobacillus strains L. rhamnosus Kx151A1, L. reuteri PTA-5289, and L. salivarius LMG9477 inhibited the initial adherence of GAS to host epithelial cells. Intriguingly, competition with a combination of Lactobacillus species reduced GAS adherence to host cells most efficiently. The data suggest that an effector molecule released from certain Lactobacillus strains attenuates the production of SLS at the transcriptional level and that combinations of Lactobacillus strains may protect the pharyngeal mucosa more efficiently from the initial colonization of GAS. The effector molecules released from Lactobacillus strains affecting the virulence phenotypes of pathogens hold potential in the development of a new generation of therapeutics. PMID:27524981

  9. Simultaneous strain and temperature measurement system with fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Zhu, Dandan; Li, Zhiquan; Sun, Fu; Tian, Xiuxian; Wang, Haifang

    2007-01-01

    Simultaneous strain and temperature measurement system with fiber Bragg grating was presented in this paper. The light from broadband source (BBS) was coupled into sensing probe through 3dB coupler1. Reflective light of two FBGs was split through coupler2 and went into chirped gratings with different pass-band. Demodulation method adopted chirped grating and long period grating edge linear filtering technology. It can send each reflected spectrum to different edge filter. It makes every FBG's reflective spectrum was demodulate. The central reflected wavelength of two FBGs was 1546.15nm and 1554.17nm respectively. Through simulation experiment, we can get that (formula available in manuscript). Strain measurement ranged from 0 to 2000 με. Temperature measurement ranged from 0 to 200°C.

  10. Relationship of cell surface morphology and composition of Streptococcus salivarius K+ to adherence and hydrophobicity.

    PubMed Central

    Weerkamp, A H; van der Mei, H C; Slot, J W

    1987-01-01

    The cell surfaces of a range of variants of Streptococcus salivarius HB, altered in cell wall antigen composition, were compared with those of the parent with respect to adherence, ability to adsorb to hexadecane, morphology, and exposure of lipoteichoic acid (LTA). Adherence to host surfaces was measured by using both saliva-coated hydroxyapatite beads and tissue-cultured HeLa cells, and interbacterial adherence was measured by using Veillonella alcalescens V1 cells. Progressive loss of the protease-sensitive fibril classes was generally associated with decreasing ability to adsorb to hexadecane. However, increased exposure of protein antigen C (AgC) increased the apparent hydrophobicity of the cell. This correlated with the finding that AgC was the most hydrophobic of the solubilized fibrillar cell wall antigens. Collectively, this demonstrates that adsorption to hydrophobic ligands is directly related to the density of the fibrillar layer on the cells and the properties and surface exposure of specific fibril classes. The involvement of hydrophobic interactions in AgC-associated attachment was suggested by its sensitivity to low levels of the hydrophobic bond-breaking agent tetramethyl urea, although the reduction was not to the level of adherence observed with strains lacking AgC. However, hydrophobicity was less essential to other adherence reactions. Circumstantial evidence, including immunoelectron microscopy, showing that LTA was virtually absent from the fibrillar layer, whole-cell enzyme-linked immunosorbent assay, suggesting that surface exposure of LTA related inversely to the density of the fibrillar layer, and agarose gel electrophoresis, showing that LTA was not specifically associated with protein fibrillar antigens, strongly suggested that LTA does not confer hydrophobic properties to these cells and is not involved in adherence reactions associated with the cell wall protein antigens. Images PMID:3804445

  11. Dynamic Strain Sensing in a Long-Span Suspension Bridge Using Fiber Bragg Grating Sensors

    NASA Astrophysics Data System (ADS)

    Zhu, Yinian; Zhu, Yan-Jin; Balogun, Oluwaseyi; Zhu, Songye; Xu, You-Lin; Krishnaswamy, Sridhar

    2011-06-01

    Optical fiber sensors are ideal for monitoring continuous deterioration conditions of civil infrastructure, especially of long-span bridges. Typically, a network of sensors is used to measure the strains or low frequency vibrational response of the structure. In this work, we demonstrate dynamic spectral demodulation of fiber Bragg grating (FBG) sensor responses with a stabilized Michelson interferometer for monitoring mechanical strains in a model of long-span bridge. A series of experiments has been performed, including the measurements of the natural resonant modes of the model bridge, impact response of a bridge member and acoustic emissions in a fractured aluminum bar. The experimental results not only reveal that dynamic spectral demodulation of FBG strain responses at frequencies extending up to about 3.5 MHz is possible, but also suggest that the method may be suitable for monitoring high frequency mechanical strains in civil structures that result from cracking or impact loading, thus providing a tool for local detection of structural damage.

  12. Clinical Supervision in Treatment Transport: Effects on Adherence and Outcomes

    PubMed Central

    Schoenwald, Sonja K.; Sheidow, Ashli J.; Chapman, Jason E.

    2009-01-01

    This non-experimental study used Mixed-Effects Regression Models (MRMs) to examine relations among supervisor adherence to a clinical supervision protocol, therapist adherence, and changes in the behavior and functioning of youth with serious antisocial behavior treated with an empirically supported treatment (i.e., Multisystemic Therapy), one-year post treatment. Participants were 1979 youth and families treated by 429 clinicians across 45 provider organizations in North America. Four dimensions of clinical supervision were examined. MRM results showed one dimension, supervisor focus on adherence to treatment principles, predicted greater therapist adherence. Two supervision dimensions, adherence to the structure and process of supervision, and focus on clinician development, predicted changes in youth behavior. Conditions required to test hypothesized mediation by therapist adherence of supervisor adherence effects on youth outcomes were not met, and direct effects of each were observed in models including both supervisor and therapist adherence. PMID:19485583

  13. Medication Adherence in Patients with Bipolar Disorder: A Comprehensive Review.

    PubMed

    Levin, Jennifer B; Krivenko, Anna; Howland, Molly; Schlachet, Rebecca; Sajatovic, Martha

    2016-09-01

    Poor medication adherence is a pervasive problem that causes disability and suffering as well as extensive financial costs among individuals with bipolar disorder (BD). Barriers to adherence are numerous and cross multiple levels, including factors related to bipolar pathology and those unique to an individual's circumstances. External factors, including treatment setting, healthcare system, and broader health policies, can also affect medication adherence in people with BD. Fortunately, advances in research have suggested avenues for improving adherence. A comprehensive review of adherence-enhancement interventions for the years 2005-2015 is included. Specific bipolar adherence-enhancement approaches that target knowledge gaps, cognitive patterns, specific barriers, and motivation may be helpful, as may approaches that capitalize on technology or novel drug-delivery systems. However, much work remains to optimally facilitate long-term medication adherence in people with BD. For adherence-enhancement approaches to be widely adapted, they need to be easily accessible, affordable, and practical. PMID:27435356

  14. Experimental and numerical analysis of a hybrid FBG long gauge sensor for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Torres Górriz, Benjamín; Calderón García, Pedro; Payá-Zaforteza, Ignacio J.; Sales Maicas, Salvador

    2014-12-01

    This paper presents a new long gauge sensor for structural health monitoring based on the use of fiber Bragg gratings. The proposed sensor has the advantage over existing sensors that it does not require prestressing of the optical fiber. The development consisted of numerical studies complemented by experimental tests to analyze: (1) the strain transfer between the sensor and the host structure; (2) the influence of sensor axial stiffness on the structural behavior of the host structure; (3) the influence of the mechanical properties of the adhesive used to fix the sensor and (4) the failure modes of the sensor (buckling and shear stress of sensor anchors).

  15. Treatment Adherence in Adolescents With Inflammatory Bowel Disease: The Collective Impact of Barriers to Adherence and Anxiety/Depressive Symptoms

    PubMed Central

    Gray, Wendy N.; Denson, Lee A.; Baldassano, Robert N.

    2012-01-01

    Objective Knowledge of factors impacting adolescents’ ability to adhere to their inflammatory bowel disease (IBD) regimen is limited. The current study examines the collective impact of barriers to adherence and anxiety/depressive symptoms on adolescent adherence to the IBD regimen. Methods Adolescents (n = 79) completed measures of barriers to adherence, adherence, and anxiety/depressive symptoms at one of two specialty pediatric IBD clinics. Results Most adolescents reported barriers to adherence and 1 in 8 reported borderline or clinically elevated levels of anxiety/depressive symptoms. Anxiety/depressive symptoms moderated the relationship between barriers to adherence and adherence. Post hoc probing revealed a significant, additive effect of higher anxiety/depressive symptoms in the barriers–adherence relationship, with adherence significantly lower among adolescents with higher barriers and higher anxiety/depressive symptoms. Conclusions In order to optimize adherence in adolescents, interventions should target not only barriers to adherence but also any anxiety/depressive symptoms that may negatively impact efforts to adhere to recommended treatment. PMID:22080456

  16. 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.

  17. Overactive bladder: strategies to ensure treatment compliance and adherence

    PubMed Central

    Dhaliwal, Prabhpreet; Wagg, Adrian

    2016-01-01

    Overactive bladder is a common, debilitating condition for many patients who may benefit from pharmacological management of their condition. However, adherence to medication in this condition is markedly worse than other chronic medical conditions. This review explores what is known about persistence and the factors which influence medication adherence for overactive bladder, those factors that might be modifiable to improve adherence, and the measures the health care provider can take to optimize adherence to therapy and thereby improve treatment outcomes. PMID:27350744

  18. Improved assay for quantitating adherence of ruminal bacteria to cellulose.

    PubMed Central

    Rasmussen, M A; White, B A; Hespell, R B

    1989-01-01

    A quantitative technique suitable for the determination of adherence of ruminal bacteria to cellulose was developed. This technique employs adherence of cells to cellulose disks and alleviates the problem of nonspecific cell entrapment within cellulose particles. By using this technique, it was demonstrated that the adherence of Ruminococcus flavefaciens FD1 to cellulose was inhibited by formaldehyde, methylcellulose, and carboxymethyl cellulose. Adherence was unaffected by acid hydrolysates of methylcellulose, glucose, and cellobiose. PMID:2782879

  19. Medication Adherence in Psychopharmacologically Treated Adults with ADHD

    ERIC Educational Resources Information Center

    Safren, Steven A.; Duran, Petra; Yovel, Iftah; Perlman, Carol A.; Sprich, Susan

    2007-01-01

    Objective: One of the potential causes of residual symptoms of ADHD in adults can be difficulties with consistent adherence to medications. Method: This formative study examined self-reported medication adherence in adults with ADHD with clinically significant symptoms despite medication treatment. Results: Mean adherence for the two-week period…

  20. A Matter of Trust: Patient Barriers to Primary Medication Adherence

    ERIC Educational Resources Information Center

    Polinski, J. M.; Kesselheim, A. S.; Frolkis, J. P.; Wescott, P.; Allen-Coleman, C.; Fischer, M. A.

    2014-01-01

    Primary medication adherence occurs when a patient properly fills the first prescription for a new medication. Primary adherence only occurs about three-quarters of the time for antihypertensive medications. We assessed patients' barriers to primary adherence and attributes of patient-provider discussions that might improve primary adherence…

  1. Evaluation of medication adherence in Lebanese hypertensive patients.

    PubMed

    Yassine, Mohammad; Al-Hajje, Amal; Awada, Sanaa; Rachidi, Samar; Zein, Salam; Bawab, Wafa; Bou Zeid, Mayssam; El Hajj, Maya; Salameh, Pascale

    2016-09-01

    Controlling hypertension is essential in cardiovascular diseases. Poor medication adherence is associated with poor disease outcomes, waste of healthcare resources, and contributes to reduced blood pressure control. This study evaluates treatment adherence to antihypertensive therapy in Lebanese hypertensive patients by estimating the proportion of adherent hypertensive patients using a validated tool and investigates what factors predict this behavior. A questionnaire-based cross-sectional study was conducted on a random sample of 210 hypertensive outpatients selected from clinics located in tertiary-care hospitals and from private cardiology clinics located in Beirut. Adherence level was measured using a validated 8-item Modified Morisky Medication Adherence Scale (MMMAS). Among 210 patients, 50.5% showed high adherence, 27.1% medium adherence, and 22.4% low adherence to medication. Mean MMMAS score was 6.59±2.0. In bivariate analyses, having controlled blood pressure (p=0.003) and taking a combination drug (p=0.023) were predictors of high adherence. Forgetfulness (p<0.01), complicated drug regimen (p=0.001), and side effects (p=0.006) were predictors of low adherence after multiple liner regression. Logistic regression results showed that calcium channel blockers (p=0.030) were associated with increased adherence levels. In conclusion, developing multidisciplinary intervention programs to address the factors identified, in addition to educational strategies targeting healthcare providers, are necessary to enhance patient adherence. PMID:26232704

  2. Adherence indicators predict changes in health outcomes: HUB City Steps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Participant adherence is a major threat to intervention effectiveness. Most researchers have reported effects of a single adherence measure on health outcomes. The objective of this analysis was to evaluate two adherence measures, separately and in combination, for predicting changes in health out...

  3. Analyzing Adherence to Prenatal Supplement: Does Pill Count Measure Up?

    PubMed Central

    Appelgren, Kristie E.; Nietert, Paul J.; Hulsey, Thomas C.; Hollis, Bruce W.; Wagner, Carol L.

    2010-01-01

    Objective. To determine if adherence as measured by pill count would show a significant association with serum-based measures of adherence. Methods. Data were obtained from a prenatal vitamin D supplementation trial where subjects were stratified by race and randomized into three dosing groups: 400 (control), 2000, or 4000 IU vitamin D3/day. One measurement of adherence was obtained via pill counts remaining compared to a novel definition for adherence using serum 25-hydroxy-vitamin D (25-OH-D) levels (absolute change in 25(OH)D over the study period and the subject's steady-state variation in their 25(OH)D levels). A multivariate logistic regression model examined whether mean percent adherence by pill count was significantly associated with the adherence measure by serum metabolite levels. Results. Subjects' mean percentage of adherence by pill count was not a significant predictor of adherence by serum metabolite levels. This finding was robust across a series of sensitivity analyses. Conclusions. Based on our novel definition of adherence, pill count was not a reliable predictor of adherence to protocol, and calls into question how adherence is measured in clinical research. Our findings have implications regarding the determination of efficacy of medications under study and offer an alternative approach to measuring adherence of long half-life supplements/medications. PMID:20169132

  4. Understanding how adherence goals promote adherence behaviours: a repeated measure observational study with HIV seropositive patients

    PubMed Central

    2012-01-01

    Background The extent to which patients follow treatments as prescribed is pivotal to treatment success. An exceptionally high level (> 95%) of HIV medication adherence is required to suppress viral replication and protect the immune system and a similarly high level (> 80%) of adherence has also been suggested in order to benefit from prescribed exercise programmes. However, in clinical practice, adherence to both often falls below the desirable level. This project aims to investigate a wide range of psychological and personality factors that may lead to adherence/non-adherence to medical treatment and exercise programmes. Methods HIV positive patients who are referred to the physiotherapist-led 10-week exercise programme as part of the standard care are continuously recruited. Data on social cognitive variables (attitude, intention, subjective norms, self-efficacy, and outcome beliefs) about the goal and specific behaviours, selected personality factors, perceived quality of life, physical activity, self-reported adherence and physical assessment are collected at baseline, at the end of the exercise programme and again 3 months later. The project incorporates objective measures of both exercise (attendance log and improvement in physical measures such as improved fitness level, weight loss, improved circumferential anthropometric measures) and medication adherence (verified by non-invasive hair analysis). Discussion The novelty of this project comes from two key aspects, complemented with objective information on exercise and medication adherence. The project assesses beliefs about both the underlying goal such as following prescribed treatment; and about the specific behaviours such as undertaking the exercise or taking the medication, using both implicit and explicit assessments of patients’ beliefs and attitudes. We predict that i) the way people think about the underlying goal of their treatments explains medication and exercise behaviours over and above

  5. In vitro inhibition of Helicobacter pylori growth and adherence to gastric mucosal cells by Pycnogenol.

    PubMed

    Rohdewald, Peter; Beil, Winfried

    2008-05-01

    The emergence of antibiotic resistant H. pylori strains has necessitated the identification of alternative additive therapies for the treatment of this infection. The study tested whether a specific pine bark extract (Pycnogenol is effective in inhibiting the growth and adherence of H. pylori in vitro. Inhibition of H. pylori growth by Pycnogenol was tested in liquid medium as well as in an in vitro model by using sessile bacteria attached to AGS cells. Adherence was determined by co-incubation of gastric cells with Pycnogenol and H. pylori in vitro. Pycnogenol inhibited H. pylori growth in suspension with an MIC(50) of 12.5 microg/mL. Growth of H. pylori in infected cells was reduced to 10% of the control value by 125 microg/mL Pycnogenol. Adherence of H. pylori to gastric cells was reduced by 70% after 3 h incubation with 125 microg/mL Pycnogenol. The results show a significant, yet limited inhibition of growth and adherence of H. pylori to gastric cells by Pycnogenol. In vivo studies have to demonstrate the clinical relevance of these findings. PMID:18350522

  6. 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

  7. Adherence and autoaggregation phenotypes of a Burkholderia cenocepacia cable pilus mutant.

    PubMed

    Tomich, Mladen; Mohr, Christian D

    2003-11-21

    Cable pili are unique peritrichous adherence organelles expressed by certain strains of the opportunistic human pathogen Burkholderia cenocepacia. Cable pili have been proposed to facilitate binding to human epithelial cells and mucin, and may play a role in the ability of B. cenocepacia to colonise the respiratory tract of compromised hosts. In this study, a genetic approach was undertaken to assess the role of cable pili in mediating adherence as well as bacterial cell-cell interactions. The cblA gene, encoding the major pilin subunit, was insertionally inactivated, and the resulting mutant was shown to be blocked in CblA expression and in cable pilus morphogenesis. Although non-piliated, the cblA mutant was not defective in adherence to either porcine mucin or to cultured A549 human respiratory epithelial cells. Microscopic and flow cytometric analyses of B. cenocepacia cultures revealed that cable pilus expression facilitated the formation of diffuse cell networks, whereas disruption of cable pilus biogenesis enhanced autoaggregation and the formation of compact cell aggregates. Autoaggregation was observed both in culture and during B. cenocepacia infection of A549 epithelial cell monolayers. These findings indicate that cable pilus expression plays an important role in mediating B. cenocepacia cell-cell interactions, and that both cable pilus-dependent and cable pilus-independent mechanisms may contribute to B. cenocepacia adherence to cellular and acellular surfaces. PMID:14638436

  8. Ethical Questions in Medical Electronic Adherence Monitoring.

    PubMed

    Campbell, Jeffrey I; Eyal, Nir; Musiimenta, Angella; Haberer, Jessica E

    2016-03-01

    Electronic adherence monitors (EAMs) record and report an array of health behaviors, ranging from taking daily medications to wearing medical devices. EAMs are utilized in research worldwide and are being investigated for clinical use. However, there is also growing popular concern about the extent to which electronic devices may be used to monitor individuals, including allegations in the media that EAMs represent a move towards "Big Brother" in medicine. Here, we highlight the unique benefits as well as the potential ethical challenges that electronic adherence monitoring generates. These challenges surround autonomy, privacy and confidentiality, trust, and ancillary care obligations. We describe key questions within each of these domains that warrant further investigation, and present potential solutions to many of the concerns raised. PMID:26358284

  9. Subpopulations in purified platelets adhering on glass.

    PubMed

    Donati, Alessia; Gupta, Swati; Reviakine, Ilya

    2016-01-01

    Understanding how platelet activation is regulated is important in the context of cardiovascular disorders and their management with antiplatelet therapy. Recent evidence points to different platelet subpopulations performing different functions. In particular, procoagulant and aggregating subpopulations have been reported in the literature in platelets treated with the GPVI agonists. How the formation of platelet subpopulations upon activation is regulated remains unclear. Here, it is shown that procoagulant and aggregating platelet subpopulations arise spontaneously upon adhesion of purified platelets on clean glass surfaces. Calcium ionophore treatment of the adhering platelets resulted in one platelet population expressing both the procoagulant and the adherent population markers phosphatidylserine and the activated form of GPIIb/IIIa, while all of the platelets expressed CD62P independently of the ionophore treatment. Therefore, all platelets have the capacity to express all three activation markers. It is concluded that platelet subpopulations observed in various studies reflect the dynamics of the platelet activation process. PMID:27338300

  10. Medication adherence in patients with schizophrenia.

    PubMed

    Phan, Stephanie V

    2016-01-01

    Medication nonadherence is common among patients with schizophrenia and due to a variety of factors including lack of insight, psychopathology, substance use disorder, issues associated with treatment, stigma, fragmentation of care, cultural influences, and socioeconomic status. Among this population, nonadherence is problematic because it can lead to decompensation or exacerbation of symptoms, relapse, rehospitalization or greater use of emergency psychiatric services, functional decline, and increased risk of death. Psychoeducational approaches alone are ineffective, but in combination with behavioral interventions, appear to be effective. Involving the patient's support system, in addition to other interventions, can improve treatment adherence. Many medication-related factors, such as effectiveness and tolerability of antipsychotics, regimen complexity, and past medication trials impact appropriate medication use. Therefore, optimizing the patient's pharmacotherapeutic regimens can improve adherence. Additional factors favorably influencing adherence include involving the patient in their treatment, fostering a therapeutic alliance, implementing/using reminder systems, and addressing substance use disorder. Medication nonadherence arises from multiple reasons that vary between patients. Thus, the most effective strategies to improve adherence are multifactorial and may involve both psychoeducational and behavioral techniques, as well as previously listed approaches. Strategies should be targeted toward the patient and their support system, whenever possible, to further improve the chances of appropriate medication use. Recognizing that all patients with schizophrenia are at risk for medication nonadherence is important. No one technique has been shown to be most effective; therefore, the risk for nonadherence should continually be assessed and multiple strategies should be targeted to the patient (and caregiver) and repeatedly implemented throughout the course

  11. Adherence with drug therapy in the rheumatic diseases Part one: a review of adherence rates.

    PubMed

    Hill, Jackie

    2005-01-01

    Drug therapy plays a major role in the management of many rheumatic diseases and is particularly important in rheumatoid arthritis (RA) because of the significant rates of morbidity and mortality (Pincus, 1995). Understanding of the pathogenesis of RA has led to the development of new and more effective drugs (Emery et al., 1999), but the ultimate efficacy of any drug therapy depends upon the patient's decision to take it. There is widespread agreement that many people with rheumatic disease do not adhere to their medication regimens (Deyo et al., 1981; Belcon et al., 1984; Pullar et al., 1988; Hill et al., 2001). Research has demonstrated that 50% of women taking hormone replacement therapy for the prevention of osteoporosis discontinue treatment after a year (Fordham, 2000) and similar rates of discontinuation are found in other chronic diseases (Haynes et al., 1996, 2000). This is bewildering as, in asymptomatic illnesses such as hypertension and diabetes, the expectation is that levels of adherence would be lower than in diseases where pain and stiffness are present. The picture becomes even more confusing when we consider the findings from a recent multi-country study of RA, which found no association between adherence and disease severity, nor with the treatment prescribed (Viller et al., 1999). In chronic disease poor adherence is commonplace. The World Health Organization (WHO) recognizes this and has recently stated that 'poor adherence to treatment of chronic diseases is a worldwide problem of striking magnitude' and cites adherence to long-term therapy for chronic illnesses in developed countries averaging just 50% (WHO, 2003). The first part of this two part review focuses on adherence with drug therapy, and the second part discusses different methods of measuring it. PMID:17041995

  12. Adherent Raindrop Modeling, Detectionand Removal in Video.

    PubMed

    You, Shaodi; Tan, Robby T; Kawakami, Rei; Mukaigawa, Yasuhiro; Ikeuchi, Katsushi

    2016-09-01

    Raindrops adhered to a windscreen or window glass can significantly degrade the visibility of a scene. Modeling, detecting and removing raindrops will, therefore, benefit many computer vision applications, particularly outdoor surveillance systems and intelligent vehicle systems. In this paper, a method that automatically detects and removes adherent raindrops is introduced. The core idea is to exploit the local spatio-temporal derivatives of raindrops. To accomplish the idea, we first model adherent raindrops using law of physics, and detect raindrops based on these models in combination with motion and intensity temporal derivatives of the input video. Having detected the raindrops, we remove them and restore the images based on an analysis that some areas of raindrops completely occludes the scene, and some other areas occlude only partially. For partially occluding areas, we restore them by retrieving as much as possible information of the scene, namely, by solving a blending function on the detected partially occluding areas using the temporal intensity derivative. For completely occluding areas, we recover them by using a video completion technique. Experimental results using various real videos show the effectiveness of our method. PMID:26485475

  13. Motivational factors of adherence to cardiac rehabilitation

    PubMed Central

    Shahsavari, Hooman; Shahriari, Mohsen; Alimohammadi, Nasrollah

    2012-01-01

    Background: Main suggested theories about patients’ adherence to treatment regimens recognize the importance of motivation in positive changes in behaviors. Since cardiac diseases are chronic and common, cardiac rehabilitation as an effective prevention program is crucial in management of these diseases. There is always concern about the patients’ adherence to cardiac rehabilitation. The aim of this study was to describe the motivational factors affecting the patients’ participation and compliance to cardiac rehabilitation by recognizing and understanding the nature of patients’ experiences. Materials and Methods: The participants were selected among the patients with cardiac diseases who were referred to cardiac rehabilitation in Isfahan Cardiovascular Research Center, Iran. The purposive sampling method was used and data saturation achieved after 8 semi-structured interviews. Findings: The three main concepts obtained from this study are “beliefs”, “supporters” and “group cohesion”. Conclusions: In cardiac rehabilitation programs, emphasis on motivational factors affects the patient’s adherence. It is suggested that in cardiac rehabilitation programs more attention should be paid to patients’ beliefs, the role of patients’ supporters and the role of group-based rehabilitation. PMID:23833634

  14. Four therapeutic diets: adherence and acceptability.

    PubMed

    Berkow, Susan E; Barnard, Neal; Eckart, Jill; Katcher, Heather

    2010-01-01

    Many health conditions are treated, at least in part, by therapeutic diets. Although the success of any intervention depends on its acceptability to the patient, the acceptability of therapeutic diets and factors that influence it have been largely neglected in nutrition research. A working definition of acceptability is proposed and an examination and summary are provided of available data on the acceptability of common diet regimens used for medical conditions. The goal is to suggest ways to improve the success of therapeutic diets. The proposed working definition of "acceptability" refers to the user's judgment of the advantages and disadvantages of a therapeutic diet-in relation to palatability, costs, and effects on eating behaviour and health-that influence the likelihood of adherence. Very low-calorie, reduced-fat omnivorous, vegetarian and vegan, and low-carbohydrate diets all achieve acceptability among the majority of users in studies of up to one year, in terms of attrition and adherence rates and results of questionnaires assessing eating behaviours. Longer studies are fewer, but they suggest that vegetarian, vegan, and reduced-fat diets are acceptable, as indicated by sustained changes in nutrient intake. Few studies of this length have been published for very low-calorie or low-carbohydrate diets. Long-term studies of adherence and acceptability of these and other therapeutic diets are warranted. PMID:21144137

  15. [Adherence to chronic medication: also a frequent problem in Belgium!].

    PubMed

    Liekens, S; Hulshagen, L; Dethier, M; Laekeman, G; Foulon, V

    2013-12-01

    Medication adherence in chronic conditions such as asthma, type 2 diabetes, heart failure, HIV and cancer appears to be a frequent problem. However, the literature on adherence in patients who use inhaled corticosteroids (ICS), oral hypoglycemic agents, drugs for heart failure, antiretrovirals or oral chemotherapy, contains little or no relevant data for Belgium. In the context of a Master thesis in Pharmaceutical care at KU Leuven, a quantitative study was performed to determine the prevalence of adherence to chronic medication in Belgium. This retrospective, cross-sectional study used a database containing refill data of a regional pharmacists' association (KLAV). Out of the 603 pharmacies affiliated with this association, all 50 pharmacies where HIV medication was delivered, were selected. Dispensing data from the selected pharmacies were collected from 01/07/2008 to 31/12/2009 for five pathologies, i.e.; asthma, type 2 diabetes, heart failure, HIV and cancer. Adherence (TT) was calculated with the Medication Refill Adherence (MRA) method. In order to determine whether there were associations between age, gender, drug class and adherence, Chi-square tests were used. Compared with the other patients, cancer patients were the most adherent in taking their drugs (median adherence rate = 88%). In addition, this was the only group in which the median adherence rate was above the set limit of 80%. The patients who were prescribed inhaled corticosteroids were the least adherent (median adherence rate = 38%). More than 50% of patients with asthma/COPD, heart failure and diabetes were classified as "under-users". Furthermore, the results showed a significant association within asthma patients between gender and adherence. In asthma, type 2 diabetes, heart failure and HIV patients there was a significant relationship between age and adherence and drug class and adherence. As the current study has some limitations, the results should be handled with caution. Nevertheless

  16. Characterization of FBG sensor interrogation based on a FDML wavelength swept laser

    PubMed Central

    Jung, Eun Joo; Kim, Chang-Seok; Jeong, Myung Yung; Kim, Moon Ki; Jeon, Min Yong; Jung, Woonggyu; Chen, Zhongping

    2012-01-01

    In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. PMID:18852764

  17. FBG application in bridge health monitoring system of Wuhan Yangtze River 2nd Bridge

    NASA Astrophysics Data System (ADS)

    Liu, Jun

    2009-10-01

    For the traditional resistance strain sensor's shortage,for example,their stability,durability and monitoring scorpe could not satisfied the requirement of bridge monitoring system,put forward to adopt advanced fiber-optic bragg grating sensor and its technology to build up the bridge health monitoring system.Analysed the application scope and aim of difference kinds of fiber bragg grating sensors used, including stress strain sensors,temperature sensors,crack sensors and testing force ring sensors.According to the key construction sections as the project designed,expatiated their specific installation methods and construction craftwork in Wuhan Yangtze River 2th bridge.It formed distributed fiber sensing network of bridge with large-scale located fiber-optic bragg grating sensors, and pointed out the becareful prodeeding when to link no more than twenty sensors to one fiber for the demodulator precision.Discussed how to construct the data acquisition system and its function via the sensors and their demodulator.One fiber of the linked sensors connected to one channel of the demodulator and all together reached sixteen channels.The demodulator were connected to the switch through rj45 interface and communicated with the acquisition server.Designed the software program of data acquisition software system and the database,which used the Sqlite of the embed database to storage the configure information and receive the data through the TCP/IP protocol.It has been build a bridge health monitoring system base on fiber bragg grating technology.

  18. 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. PMID:25322426

  19. The functions of the variable lipoprotein family of Mycoplasma hyorhinis in adherence to host cells.

    PubMed

    Xiong, Qiyan; Wang, Jia; Ji, Yan; Ni, Bo; Zhang, Bixiong; Ma, Qinghong; Wei, Yanna; Xiao, Shaobo; Feng, Zhixin; Liu, Maojun; Shao, Guoqing

    2016-04-15

    Mycoplasma hyorhinis (M. hyorhinis) is a swine pathogen that is associated with various human cancers and contamination in cell cultures. However, no studies on the adhesion molecules of this pathogen have yet been reported. The variable lipoprotein (Vlp) family is an important surface component of M. hyorhinis. Herein, we performed several experiments to identify the function of the Vlp family in adherence to host cells. Seven recombinant Vlp (rVlp) proteins were expressed in Escherichia coli and purified by affinity chromatography. The potential role of rVlp adherence to pig kidney (PK-15) and swine tracheal epithelial (STEC) cells was then studied by indirect immunofluorescence assay and microtiter plate adherence assay. Adhesion of M. hyorhinis to PK-15 and STEC cells was specifically inhibited by the addition of a cocktail of rVlp proteins. The rVlp protein mixture was shown to bind to both PK-15 and STEC cells. The binding increased in a dose-dependent manner and could be blocked by antisera against the rVlp proteins. Most of the rVlp proteins could bind individually to both PK-15 and STEC cells except for rVlpD and rVlpF, which bound only to STEC cells. Because Vlp members vary in size among different strains and generations, they may vary in their cytoadhesion capabilities in various strains. In summary, the present results indicate that the Vlp family functions as adhesins of M. hyorhinis. PMID:27016761

  20. Xylitol and erythritol decrease adherence of polysaccharide-producing oral streptococci.

    PubMed

    Söderling, Eva M; Hietala-Lenkkeri, Aija-Maaria

    2010-01-01

    Xylitol consumption decreases counts of mutans streptococci. However, the mechanism behind this decrease is not well understood. We studied not only type strains and clinical isolates of mutans streptococci, but also other polysaccharide-forming oral streptococci. Growth inhibition and adherence of cells to a smooth glass surface-reflecting synthesis of water-insoluble polysaccharides were studied in the presence of 2% (0.13 mol/l) and 4% (0.26 mol/l) xylitol. The effect of xylitol was compared to a novel polyol sweetener, erythritol. Except for Streptococcus mutans 10449 and S. sobrinus OMZ 176, the glass surface adhesion of most polysaccharide-forming streptococci was reduced by the presence of both 4% xylitol and erythritol. For the S. mutans and S. sobrinus type strains, the growth inhibition with 4% xylitol and erythritol was 36-77% and for the clinical S. mutans isolates 13-73%. Of the other oral streptococci, only S. sanguinis was inhibited with 4% xylitol (45-55%). For both polyols, the magnitude of the growth inhibition observed was not associated with the magnitude of the decrease in adherence (xylitol: r = -0.18; erythritol: r = 0.49). In conclusion, both xylitol and erythritol can decrease polysaccharide-mediated cell adherence contributing to plaque accumulation through a mechanism not dependent on growth inhibition. PMID:19777305