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Sample records for dual fret sensors

  1. Simultaneous live cell imaging using dual FRET sensors with a single excitation light.

    Directory of Open Access Journals (Sweden)

    Yusuke Niino

    Full Text Available Fluorescence resonance energy transfer (FRET between fluorescent proteins is a powerful tool for visualization of signal transduction in living cells, and recently, some strategies for imaging of dual FRET pairs in a single cell have been reported. However, these necessitate alteration of excitation light between two different wavelengths to avoid the spectral overlap, resulting in sequential detection with a lag time. Thus, to follow fast signal dynamics or signal changes in highly motile cells, a single-excitation dual-FRET method should be required. Here we reported this by using four-color imaging with a single excitation light and subsequent linear unmixing to distinguish fluorescent proteins. We constructed new FRET sensors with Sapphire/RFP to combine with CFP/YFP, and accomplished simultaneous imaging of cAMP and cGMP in single cells. We confirmed that signal amplitude of our dual FRET measurement is comparable to of conventional single FRET measurement. Finally, we demonstrated to monitor both intracellular Ca(2+ and cAMP in highly motile cardiac myocytes. To cancel out artifacts caused by the movement of the cell, this method expands the applicability of the combined use of dual FRET sensors for cell samples with high motility.

  2. Rational design of FRET-based sensor proteins

    NARCIS (Netherlands)

    Merkx, M.

    2008-01-01

    Real-time imaging of molecular events inside living cells is important for understanding the basis of physiological processes and diseases. Genetically encoded sensors that use fluorescence resonance energy transfer (FRET) between two fluorescent proteins are attractive in this respect because they

  3. Flow Cytometry Enables Multiplexed Measurements of Genetically Encoded Intramolecular FRET Sensors Suitable for Screening.

    Science.gov (United States)

    Doucette, Jaimee; Zhao, Ziyan; Geyer, Rory J; Barra, Melanie M; Balunas, Marcy J; Zweifach, Adam

    2016-07-01

    Genetically encoded sensors based on intramolecular FRET between CFP and YFP are used extensively in cell biology research. Flow cytometry has been shown to offer a means to measure CFP-YFP FRET; we suspected it would provide a unique way to conduct multiplexed measurements from cells expressing different FRET sensors, which is difficult to do with microscopy, and that this could be used for screening. We confirmed that flow cytometry accurately measures FRET signals using cells transiently transfected with an ERK activity reporter, comparing responses measured with imaging and cytometry. We created polyclonal long-term transfectant lines, each expressing a different intramolecular FRET sensor, and devised a way to bar-code four distinct populations of cells. We demonstrated the feasibility of multiplexed measurements and determined that robust multiplexed measurements can be conducted in plate format. To validate the suitability of the method for screening, we measured responses from a plate of bacterial extracts that in unrelated experiments we had determined contained the protein kinase C (PKC)-activating compound teleocidin A-1. The multiplexed assay correctly identifying the teleocidin A-1-containing well. We propose that multiplexed cytometric FRET measurements will be useful for analyzing cellular function and for screening compound collections. © 2016 Society for Laboratory Automation and Screening.

  4. A comparison of donor-acceptor pairs for genetically encoded FRET sensors: application to the Epac cAMP sensor as an example.

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    Gerard N M van der Krogt

    Full Text Available We recently reported on CFP-Epac-YFP, an Epac-based single polypeptide FRET reporter to resolve cAMP levels in living cells. In this study, we compared and optimized the fluorescent protein donor/acceptor pairs for use in biosensors such as CFP-Epac-YFP. Our strategy was to prepare a wide range of constructs consisting of different donor and acceptor fluorescent proteins separated by a short linker. Constructs were expressed in HEK293 cells and tested for FRET and other relevant properties. The most promising pairs were subsequently used in an attempt to improve the FRET span of the Epac-based cAMP sensor. The results show significant albeit not perfect correlation between performance in the spacer construct and in the Epac sensor. Finally, this strategy enabled us to identify improved sensors both for detection by sensitized emission and by fluorescent lifetime imaging. The present overview should be helpful in guiding development of future FRET sensors.

  5. Ultrasensitive FRET-based DNA sensor using PNA/DNA hybridization.

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    Yang, Lan-Hee; Ahn, Dong June; Koo, Eunhae

    2016-12-01

    In the diagnosis of genetic diseases, rapid and highly sensitive DNA detection is crucial. Therefore, many strategies for detecting target DNA have been developed, including electrical, optical, and mechanical methods. Herein, a highly sensitive FRET based sensor was developed by using PNA (Peptide Nucleic Acid) probe and QD, in which red color QDs are hybridized with capture probes, reporter probes and target DNAs by EDC-NHS coupling. The hybridized probe with target DNA gives off fluorescent signal due to the energy transfer from QD to Cy5 dye in the reporter probe. Compared to the conventional DNA sensor using DNA probes, the DNA sensor using PNA probes shows higher FRET factor and efficiency due to the higher reactivity between PNA and target DNA. In addition, to elicit the effect of the distance between the donor and the acceptor, we have investigated two types of the reporter probes having Cy5 dyes attached at the different positions of the reporter probes. Results show that the shorter the distance between QDs and Cy5s, the stronger the signal intensity. Furthermore, based on the fluorescence microscopy images using microcapillary chips, the FRET signal is enhanced to be up to 276% times stronger than the signal obtained using the cuvette by the fluorescence spectrometer. These results suggest that the PNA probe system conjugated with QDs can be used as ultrasensitive DNA nanosensors. Copyright © 2016. Published by Elsevier B.V.

  6. FRET-mediated pH-responsive dual fluorescent nanoparticles prepared via click chemistry

    Science.gov (United States)

    Ouadahi, Karima; Sbargoud, Kamal; Allard, Emmanuel; Larpent, Chantal

    2012-01-01

    Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength.Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength. Electronic supplementary information (ESI) available: Experimental details and figures S1-S16 as mentioned in the text. See DOI: 10.1039/c2nr11413e

  7. Developing Fast Fluorescent Protein Voltage Sensors by Optimizing FRET Interactions.

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    Uhna Sung

    Full Text Available FRET (Förster Resonance Energy Transfer-based protein voltage sensors can be useful for monitoring neuronal activity in vivo because the ratio of signals between the donor and acceptor pair reduces common sources of noise such as heart beat artifacts. We improved the performance of FRET based genetically encoded Fluorescent Protein (FP voltage sensors by optimizing the location of donor and acceptor FPs flanking the voltage sensitive domain of the Ciona intestinalis voltage sensitive phosphatase. First, we created 39 different "Nabi1" constructs by positioning the donor FP, UKG, at 8 different locations downstream of the voltage-sensing domain and the acceptor FP, mKO, at 6 positions upstream. Several of these combinations resulted in large voltage dependent signals and relatively fast kinetics. Nabi1 probes responded with signal size up to 11% ΔF/F for a 100 mV depolarization and fast response time constants both for signal activation (~2 ms and signal decay (~3 ms. We improved expression in neuronal cells by replacing the mKO and UKG FRET pair with Clover (donor FP and mRuby2 (acceptor FP to create Nabi2 probes. Nabi2 probes also had large signals and relatively fast time constants in HEK293 cells. In primary neuronal culture, a Nabi2 probe was able to differentiate individual action potentials at 45 Hz.

  8. Detection of protease activity by fluorescent protein FRET sensors: from computer simulation to live cells

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    Goryashchenko, Alexander S.; Khrenova, Maria G.; Savitsky, Alexander P.

    2018-04-01

    Förster resonance energy transfer (FRET) sensors are widely used for the detection of protease activity in vitro and in vivo. Usually they consist of a FRET pair connected with a polypeptide linker containing a specific cleavage site for the relevant protease. Use of the fluorescent proteins as components of the FRET pair allows genetic encoding of such sensors and solves the problem of their delivery into live cells and animals. There are several ways to improve the properties of such sensors, mainly to increase FRET efficiency and therefore the dynamic range. One of the ways to achieve this is to use a non-fluorescent chromoprotein as an acceptor. Molecular dynamic simulations may assist in the construction of linker structures connecting donor and acceptor molecules. Estimation of the orientation factor κ 2 can be obtained by methods based on quantum theory and combined quantum mechanics/molecular mechanics approaches. The linker can be structured by hydrophobic interactions, bringing it into a closed conformation that shortens the distance between donor and acceptor and, consequently, increases FRET efficiency. We analyzed the effects of different linker structures on the detection of caspase-3 activity using a non-fluorescent acceptor. Also we have constructed the Tb3+- TagRFP sensor in which a complex of the terbium ion and terbium-binding peptide is used as a donor. This allowed us to use the unique property of lanthanide ions—fluorescence lifetime up to milliseconds—to perform measurements with time delay and exclude the nanosecond-order fluorescence. Using our systems as a starting point, by changing the recognition site in the linker it is possible to perform imaging of different protease activity in vitro or in vivo.

  9. Chemical synthesis of dual labeled proteins via differently protected alkynes enables intramolecular FRET analysis.

    Science.gov (United States)

    Hayashi, Gosuke; Kamo, Naoki; Okamoto, Akimitsu

    2017-05-30

    We report a novel method for multisite protein conjugation by setting differently silyl-protected alkynes as conjugation handles, which can remain intact through the whole synthetic procedure and provide sequential and orthogonal conjugation. This strategy enables efficient preparation of a dual dye-labeled protein and structural analysis via an intramolecular FRET mechanism.

  10. QD-Based FRET Probes at a Glance

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    Armen Shamirian

    2015-06-01

    Full Text Available The unique optoelectronic properties of quantum dots (QDs give them significant advantages over traditional organic dyes, not only as fluorescent labels for bioimaging, but also as emissive sensing probes. QD sensors that function via manipulation of fluorescent resonance energy transfer (FRET are of special interest due to the multiple response mechanisms that may be utilized, which in turn imparts enhanced flexibility in their design. They may also function as ratiometric, or “color-changing” probes. In this review, we describe the fundamentals of FRET and provide examples of QD-FRET sensors as grouped by their response mechanisms such as link cleavage and structural rearrangement. An overview of early works, recent advances, and various models of QD-FRET sensors for the measurement of pH and oxygen, as well as the presence of metal ions and proteins such as enzymes, are also provided.

  11. Fiber Fabry-Perot Force Sensor with Small Volume and High Performance for Assessing Fretting Damage of Steam Generator Tubes.

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    Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie

    2017-12-13

    Measuring the radial collision force between the steam generator tube (SGT) and the tube support plate (TSP) is essential to assess the fretting damage of the SGT. In order to measure the radial collision force, a novel miniaturized force sensor based on fiber Fabry-Perot (F-P) was designed, and the principle and characteristics of the sensor were analyzed in detail. Then, the F-P force sensor was successfully fabricated and calibrated, and the overall dimensions of the encapsulated fiber F-P sensor were 17 mm × 5 mm × 3 mm (L × W × H). The sensor works well in humid, high pressure (10 MPa), high temperature (350 °C), and vibration (40 kHz) environments. Finally, the F-P force sensors were installed in a 1:1 steam generator test loop, and the radial collision force signals between the SGT and the TSP were obtained. The experiments indicated that the F-P sensor with small volume and high performance could help in assessing the fretting damage of the steam generator tubes.

  12. A New FRET-Based Sensitive DNA Sensor for Medical Diagnostics using PNA Probe and Water-Soluble Blue Light Emitting Polymer

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    Nidhi Mathur

    2008-01-01

    Full Text Available A reliable, fast, and low-cost biosensor for medical diagnostics using DNA sequence detection has been developed and tested for the detection of the bacterium “Bacillus anthracis.” In this sensor, Poly [9,9-di (6,6′- N, N′ trimethylammonium hexylfluorenyl-2, 7-diyl-alt-co- (1,4-phenylene] dibromide salt (PFP has been taken as cationic conjugated polymer (CCP and PNA attached with fluorescein dye (PNAC∗ as a probe. The basic principle of this sensor is that when a PNAC∗ probe is hybridized with a single strand DNA (ssDNA having complementary sequence, Forster resonance energy transfer (FRET may take place from PFP to the PNAC∗/DNA complex. If the FRET is efficient, the photoluminescence from the PFP will be highly quenched and that from PNAC∗ will be enhanced. On the other hand, if the DNA sequence is noncomplementary to PNA, FRET will not occur.

  13. A New Generation of FRET Sensors for Robust Measurement of Gαi1, Gαi2 and Gαi3 Activation Kinetics in Single Cells.

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    Jakobus van Unen

    Full Text Available G-protein coupled receptors (GPCRs can activate a heterotrimeric G-protein complex with subsecond kinetics. Genetically encoded biosensors based on Förster resonance energy transfer (FRET are ideally suited for the study of such fast signaling events in single living cells. Here we report on the construction and characterization of three FRET biosensors for the measurement of Gαi1, Gαi2 and Gαi3 activation. To enable quantitative long-term imaging of FRET biosensors with high dynamic range, fluorescent proteins with enhanced photophysical properties are required. Therefore, we use the currently brightest and most photostable CFP variant, mTurquoise2, as donor fused to Gαi subunit, and cp173Venus fused to the Gγ2 subunit as acceptor. The Gαi FRET biosensors constructs are expressed together with Gβ1 from a single plasmid, providing preferred relative expression levels with reduced variation in mammalian cells. The Gαi FRET sensors showed a robust response to activation of endogenous or over-expressed alpha-2A-adrenergic receptors, which was inhibited by pertussis toxin. Moreover, we observed activation of the Gαi FRET sensor in single cells upon stimulation of several GPCRs, including the LPA2, M3 and BK2 receptor. Furthermore, we show that the sensors are well suited to extract kinetic parameters from fast measurements in the millisecond time range. This new generation of FRET biosensors for Gαi1, Gαi2 and Gαi3 activation will be valuable for live-cell measurements that probe Gαi activation.

  14. Fluorescence Lifetime Readouts of Troponin-C-Based Calcium FRET Sensors: A Quantitative Comparison of CFP and mTFP1 as Donor Fluorophores

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    Laine, Romain; Stuckey, Daniel W.; Manning, Hugh; Warren, Sean C.; Kennedy, Gordon; Carling, David

    2012-01-01

    We have compared the performance of two Troponin-C-based calcium FRET sensors using fluorescence lifetime read-outs. The first sensor, TN-L15, consists of a Troponin-C fragment inserted between CFP and Citrine while the second sensor, called mTFP-TnC-Cit, was realized by replacing CFP in TN-L15 with monomeric Teal Fluorescent Protein (mTFP1). Using cytosol preparations of transiently transfected mammalian cells, we have measured the fluorescence decay profiles of these sensors at controlled concentrations of calcium using time-correlated single photon counting. These data were fitted to discrete exponential decay models using global analysis to determine the FRET efficiency, fraction of donor molecules undergoing FRET and calcium affinity of these sensors. We have also studied the decay profiles of the donor fluorescent proteins alone and determined the sensitivity of the donor lifetime to temperature and emission wavelength. Live-cell fluorescence lifetime imaging (FLIM) of HEK293T cells expressing each of these sensors was also undertaken. We confirmed that donor fluorescence of mTFP-TnC-Cit fits well to a two-component decay model, while the TN-L15 lifetime data was best fitted to a constrained four-component model, which was supported by phasor analysis of the measured lifetime data. If the constrained global fitting is employed, the TN-L15 sensor can provide a larger dynamic range of lifetime readout than the mTFP-TnC-Cit sensor but the CFP donor is significantly more sensitive to changes in temperature and emission wavelength compared to mTFP and, while the mTFP-TnC-Cit solution phase data broadly agreed with measurements in live cells, this was not the case for the TN-L15 sensor. Our titration experiment also indicates that a similar precision in determination of calcium concentration can be achieved with both FRET biosensors when fitting a single exponential donor fluorescence decay model to the fluorescence decay profiles. We therefore suggest that m

  15. Compound parabolic concentrator optical fiber tip for FRET-based fluorescent sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren

    2015-01-01

    The Compound Parabolic Concentrator (CPC) optical fiber tip shape has been proposed for intensity based fluorescent sensors working on the principle of FRET (Förster Resonance Energy Transfer). A simple numerical Zemax model has been used to optimize the CPC tip geometry for a step-index multimode...... polymer optical fiber for an excitation and emission wavelength of 550 nm and 650nm, respectively. The model suggests an increase of a factor of 1.6 to 4 in the collected fluorescent power for an ideal CPC tip, as compared to the plane-cut fiber tip for fiber lengths between 5 and 45mm...

  16. Abscisic acid dynamics in roots detected with genetically encoded FRET sensors

    Science.gov (United States)

    Jones, Alexander M; Danielson, Jonas ÅH; ManojKumar, Shruti N; Lanquar, Viviane; Grossmann, Guido; Frommer, Wolf B

    2014-01-01

    Cytosolic hormone levels must be tightly controlled at the level of influx, efflux, synthesis, degradation and compartmentation. To determine ABA dynamics at the single cell level, FRET sensors (ABACUS) covering a range ∼0.2–800 µM were engineered using structure-guided design and a high-throughput screening platform. When expressed in yeast, ABACUS1 detected concentrative ABA uptake mediated by the AIT1/NRT1.2 transporter. Arabidopsis roots expressing ABACUS1-2µ (Kd∼2 µM) and ABACUS1-80µ (Kd∼80 µM) respond to perfusion with ABA in a concentration-dependent manner. The properties of the observed ABA accumulation in roots appear incompatible with the activity of known ABA transporters (AIT1, ABCG40). ABACUS reveals effects of external ABA on homeostasis, that is, ABA-triggered induction of ABA degradation, modification, or compartmentation. ABACUS can be used to study ABA responses in mutants and quantitatively monitor ABA translocation and regulation, and identify missing components. The sensor screening platform promises to enable rapid fine-tuning of the ABA sensors and engineering of plant and animal hormone sensors to advance our understanding of hormone signaling. DOI: http://dx.doi.org/10.7554/eLife.01741.001 PMID:24737862

  17. A communication theoretical analysis of FRET-based mobile ad hoc molecular nanonetworks.

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    Kuscu, Murat; Akan, Ozgur B

    2014-09-01

    Nanonetworks refer to a group of nanosized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Förster Resonance Energy Transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, for the first time in the literature, we investigate the network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation based on birth-death processes with continuous time Markov chains. We evaluate the performance of FRET-MSAN and FRET-MAMNET in terms of successful transmission probability and mean extinction time of the messages, system throughput, channel capacity and achievable communication rates.

  18. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection.

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    Yao, B C; Wu, Y; Yu, C B; He, J R; Rao, Y J; Gong, Y; Fu, F; Chen, Y F; Li, Y R

    2016-03-24

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel 'FRET on Fiber' concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based 'FRET on fiber' configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated 'FRET on Fiber' sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response.

  19. Dual Mechanism of an Intramolecular Charge Transfer (ICT)-FRET-Based Fluorescent Probe for the Selective Detection of Hydrogen Peroxide.

    Science.gov (United States)

    Liang, Xiao; Xu, Xiaoyi; Qiao, Dan; Yin, Zheng; Shang, Luqing

    2017-12-14

    A dual-mechanism intramolecular charge transfer (ICT)-FRET fluorescent probe for the selective detection of H 2 O 2 in living cells has been designed and synthesized. This probe used a coumarin-naphthalimide hybrid as the FRET platform and a boronate moiety as the recognition group. Upon the addition of H 2 O 2 , the probe exhibited a redshifted (73 nm) fluorescence emission, and the ratio of fluorescence intensities at λ=558 and 485 nm (F 558 /F 485 ) shifted notably (up to 100-fold). Moreover, there was a good linearity (R 2 =0.9911) between the ratio and concentration of H 2 O 2 in the range of 0 to 60 μm, with a limit of detection of 0.28 μm (signal to noise ratio (S/N)=3). This probe could also detect enzymatically generated H 2 O 2 . Importantly, it could be used to visualize endogenous H 2 O 2 produced by stimulation from epidermal growth factor. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. CdSe/ZnS quantum dots conjugated with a fluorescein derivative: a FRET-based pH sensor for physiological alkaline conditions.

    Science.gov (United States)

    Kurabayashi, Tomokazu; Funaki, Nayuta; Fukuda, Takeshi; Akiyama, Shinnosuke; Suzuki, Miho

    2014-01-01

    Dual pH-dependent fluorescence peaks from a semiconductor quantum dot (QD) and a pH-dependent fluorescent dye can be measured by irradiating with a single wavelength light, and the pH can be estimated from the ratio of the fluorescent intensity of the two peaks. In this work, ratiometric pH sensing was achieved in an aqueous environment by a fluorescent CdSe/ZnS QD appended with a pH-sensitive organic dye, based on fluorescence resonance energy transfer (FRET). By functionalizing the CdSe/ZnS QD with 5-(and 6)-carboxynaphthofluorescein succinimidyl ester as a pH-dependent fluorescent dye, we succeeded in fabricating sensitive nanocomplexes with a linear response to a broad range of physiological pH levels (7.5-9.5) when excited at 450 nm. We found that a purification process is important for increasing the high-fluorescence intensity ratio of a ratiometric fluorescence pH-sensor, and the fluorescence intensity ratio was improved up to 1.0 at pH 8.0 after the purification process to remove unreacted CdSe/ZnS QDs even though the fluorescence of the dye could not be observed without the purification process. The fluorescence intensity ratio corresponds to the fluorescence intensity of the dye, and this fluorescent dye exhibited pH-dependent fluorescence intensity changes. These facts indicate that the fluorescence intensity ratio linearly increased with increasing pH value of the buffer solution containing the QD and the dye. The FRET efficiencies changed from 0.3 (pH 7.5) to 6.2 (pH 9.5).

  1. Dual-Shell Fluorescent Nanoparticles for Self-Monitoring of pH-Responsive Molecule-Releasing in a Visualized Way.

    Science.gov (United States)

    Yang, Lingang; Cui, Chuanfeng; Wang, Lingzhi; Lei, Juying; Zhang, Jinlong

    2016-07-27

    The rational design and controlled synthesis of a smart device with flexibly tailored response ability is all along desirable for bioapplication but long remains a considerable challenge. Here, a pH-stimulated valve system with a visualized "on-off" mode is constructed through a dual-shell fluorescence resonance energy transfer (FRET) strategy. The dual shells refer to carbon dots and fluorescent molecules embedded polymethacrylic acid (F-PMAA) layers successively coating around a SiO2 core (ca. 120 nm), which play the roles as energy donor and acceptor, respectively. The total thickness of the dual-shell in the solid composite is ca. 10 nm. The priorities of this dual-shell FRET nanovalve stem from three facts: (1) the thin shell allows the formation of efficient FRET system without chemical bonding between energy donor and acceptor; (2) the maximum emission wavelength of CD layer is tunable in the range of 400-600 nm, thus providing a flexible energy donor for a wide variety of energy acceptors; (3) the outer F-PMAA shell with a pH-sensitive swelling-shrinking (on-off) behavior functions as a valve for regulating the FRET process. As such, a sensitive and stable pH ratiometric sensor with a working pH range of 3-6 has been built by simply encapsulating pH-responsive fluorescein isothiocyanate (FITC) into PMAA; a pH-dependent swelling-shrinking shuttle carrier with a finely controllable molecule-release behavior has been further fabricated using rhodamine B isothiocyanate (RBITC) as the energy donor and model guest molecule. Significantly, the controlled releasing process is visually self-monitorable.

  2. A virus-MIPs fluorescent sensor based on FRET for highly sensitive detection of JEV.

    Science.gov (United States)

    Liang, Caishuang; Wang, Huan; He, Kui; Chen, Chunyan; Chen, Xiaoming; Gong, Hang; Cai, Changqun

    2016-11-01

    Major stumbling blocks in the recognition and detection of virus are the unstable biological recognition element or the complex detection means. Here a fluorescent sensor based on virus-molecular imprinted polymers (virus-MIPs) was designed for specific recognition and highly sensitive detection of Japanese encephalitis virus (JEV). The virus-MIPs were anchored on the surface of silica microspheres modified by fluorescent dye, pyrene-1-carboxaldehyde (PC). The fluorescence intensity of PC can be enhanced by the principle of fluorescence resonance energy transfer (FRET), where virus acted as energy donor and PC acted as energy acceptor. The enhanced fluorescence intensity was proportional to the concentration of virus in the range of 24-960pM, with a limit of detection (LOD, 3σ) of 9.6pM, and the relative standard deviation was 1.99%. In additional, the specificity study confirmed the resultant MIPs has high-selectivity for JEV. This sensor would become a new key for the detection of virus because of its high sensitive, simple operation, high stability and low cost. Copyright © 2016. Published by Elsevier B.V.

  3. Development of FRET biosensors for mammalian and plant systems

    NARCIS (Netherlands)

    Hamers, D.; van Voorst Vader, L.; Borst, J.W.; Goedhart, J.

    2014-01-01

    Genetically encoded biosensors are increasingly used in visualising signalling processes in different organisms. Sensors based on green fluorescent protein technology are providing a great opportunity for using Forster resonance energy transfer (FRET) as a tool that allows for monitoring dynamic

  4. 48-spot single-molecule FRET setup with periodic acceptor excitation

    Science.gov (United States)

    Ingargiola, Antonino; Segal, Maya; Gulinatti, Angelo; Rech, Ivan; Labanca, Ivan; Maccagnani, Piera; Ghioni, Massimo; Weiss, Shimon; Michalet, Xavier

    2018-03-01

    Single-molecule Förster resonance energy transfer (smFRET) allows measuring distances between donor and acceptor fluorophores on the 3-10 nm range. Solution-based smFRET allows measurement of binding-unbinding events or conformational changes of dye-labeled biomolecules without ensemble averaging and free from surface perturbations. When employing dual (or multi) laser excitation, smFRET allows resolving the number of fluorescent labels on each molecule, greatly enhancing the ability to study heterogeneous samples. A major drawback to solution-based smFRET is the low throughput, which renders repetitive measurements expensive and hinders the ability to study kinetic phenomena in real-time. Here we demonstrate a high-throughput smFRET system that multiplexes acquisition by using 48 excitation spots and two 48-pixel single-photon avalanche diode array detectors. The system employs two excitation lasers allowing separation of species with one or two active fluorophores. The performance of the system is demonstrated on a set of doubly labeled double-stranded DNA oligonucleotides with different distances between donor and acceptor dyes along the DNA duplex. We show that the acquisition time for accurate subpopulation identification is reduced from several minutes to seconds, opening the way to high-throughput screening applications and real-time kinetics studies of enzymatic reactions such as DNA transcription by bacterial RNA polymerase.

  5. Dual-reflector configuration in varied line-space grating displacement sensor

    International Nuclear Information System (INIS)

    Liu Zhengkun; Xu Xiangdong; Fu Shaojun; Zhou Qin; Liu Bin

    2008-01-01

    A method to improve the accuracy of the wavelength encoding varied line-space grating displacement sensor is presented. Based on the detailed analysis of the measured displacement errors from the single-mirror configuration sensor, a dual-reflector configuration is used to replace the previous configuration, and greatly decreases its errors. Experiments are conducted in order to make comparison of the two configurations. The results show that the measured displacement error of the sensor with dual-reflector configuration is lower than 0.03 mm in full scale (0 to 50 mm), only about 10% of the sensor with single-mirror configuration

  6. Roughness Effects on Fretting Fatigue

    Science.gov (United States)

    Yue, Tongyan; Abdel Wahab, Magd

    2017-05-01

    Fretting is a small oscillatory relative motion between two normal loaded contact surfaces. It may cause fretting fatigue, fretting wear and/or fretting corrosion damage depending on various fretting couples and working conditions. Fretting fatigue usually occurs at partial slip condition, and results in catastrophic failure at the stress levels below the fatigue limit of the material. Many parameters may affect fretting behaviour, including the applied normal load and displacement, material properties, roughness of the contact surfaces, frequency, etc. Since fretting damage is undesirable due to contacting, the effect of rough contact surfaces on fretting damage has been studied by many researchers. Experimental method on this topic is usually focusing on rough surface effects by finishing treatment and random rough surface effects in order to increase fretting fatigue life. However, most of numerical models on roughness are based on random surface. This paper reviewed both experimental and numerical methodology on the rough surface effects on fretting fatigue.

  7. A Toolbox of Genetically Encoded FRET-Based Biosensors for Rapid l-Lysine Analysis

    Directory of Open Access Journals (Sweden)

    Victoria Steffen

    2016-09-01

    Full Text Available Background: The fast development of microbial production strains for basic and fine chemicals is increasingly carried out in small scale cultivation systems to allow for higher throughput. Such parallelized systems create a need for new rapid online detection systems to quantify the respective target compound. In this regard, biosensors, especially genetically encoded Förster resonance energy transfer (FRET-based biosensors, offer tremendous opportunities. As a proof-of-concept, we have created a toolbox of FRET-based biosensors for the ratiometric determination of l-lysine in fermentation broth. Methods: The sensor toolbox was constructed based on a sensor that consists of an optimized central lysine-/arginine-/ornithine-binding protein (LAO-BP flanked by two fluorescent proteins (enhanced cyan fluorescent protein (ECFP, Citrine. Further sensor variants with altered affinity and sensitivity were obtained by circular permutation of the binding protein as well as the introduction of flexible and rigid linkers between the fluorescent proteins and the LAO-BP, respectively. Results: The sensor prototype was applied to monitor the extracellular l-lysine concentration of the l-lysine producing Corynebacterium glutamicum (C. glutamicum strain DM1933 in a BioLector® microscale cultivation device. The results matched well with data obtained by HPLC analysis and the Ninhydrin assay, demonstrating the high potential of FRET-based biosensors for high-throughput microbial bioprocess optimization.

  8. Ratiometric fluorescent sensing of pH values in living cells by dual-fluorophore-labeled i-motif nanoprobes.

    Science.gov (United States)

    Huang, Jin; Ying, Le; Yang, Xiaohai; Yang, Yanjing; Quan, Ke; Wang, He; Xie, Nuli; Ou, Min; Zhou, Qifeng; Wang, Kemin

    2015-09-01

    We designed a new ratiometric fluorescent nanoprobe for sensing pH values in living cells. Briefly, the nanoprobe consists of a gold nanoparticle (AuNP), short single-stranded oligonucleotides, and dual-fluorophore-labeled i-motif sequences. The short oligonucleotides are designed to bind with the i-motif sequences and immobilized on the AuNP surface via Au-S bond. At neutral pH, the dual fluorophores are separated, resulting in very low fluorescence resonance energy transfer (FRET) efficiency. At acidic pH, the i-motif strands fold into a quadruplex structure and leave the AuNP, bringing the dual fluorophores into close proximity, resulting in high FRET efficiency, which could be used as a signal for pH sensing. The nanoprobe possesses abilities of cellular transfection, enzymatic protection, fast response and quantitative pH detection. The in vitro and intracellular applications of the nanoprobe were demonstrated, which showed excellent response in the physiological pH range. Furthermore, our experimental results suggested that the nanoprobe showed excellent spatial and temporal resolution in living cells. We think that the ratiometric sensing strategy could potentially be applied to create a variety of new multicolor sensors for intracellular detection.

  9. Hyperspectral imaging for simultaneous measurements of two FRET biosensors in pancreatic β-cells.

    Science.gov (United States)

    Elliott, Amicia D; Bedard, Noah; Ustione, Alessandro; Baird, Michelle A; Davidson, Michael W; Tkaczyk, Tomasz; Piston, David W

    2017-01-01

    Fluorescent protein (FP) biosensors based on Förster resonance energy transfer (FRET) are commonly used to study molecular processes in living cells. There are FP-FRET biosensors for many cellular molecules, but it remains difficult to perform simultaneous measurements of multiple biosensors. The overlapping emission spectra of the commonly used FPs, including CFP/YFP and GFP/RFP make dual FRET measurements challenging. In addition, a snapshot imaging modality is required for simultaneous imaging. The Image Mapping Spectrometer (IMS) is a snapshot hyperspectral imaging system that collects high resolution spectral data and can be used to overcome these challenges. We have previously demonstrated the IMS's capabilities for simultaneously imaging GFP and CFP/YFP-based biosensors in pancreatic β-cells. Here, we demonstrate a further capability of the IMS to image simultaneously two FRET biosensors with a single excitation band, one for cAMP and the other for Caspase-3. We use these measurements to measure simultaneously cAMP signaling and Caspase-3 activation in pancreatic β-cells during oxidative stress and hyperglycemia, which are essential components in the pathology of diabetes.

  10. Stretchable Dual-Capacitor Multi-Sensor for Touch-Curvature-Pressure-Strain Sensing.

    Science.gov (United States)

    Jin, Hanbyul; Jung, Sungchul; Kim, Junhyung; Heo, Sanghyun; Lim, Jaeik; Park, Wonsang; Chu, Hye Yong; Bien, Franklin; Park, Kibog

    2017-09-07

    We introduce a new type of multi-functional capacitive sensor that can sense several different external stimuli. It is fabricated only with polydimethylsiloxane (PDMS) films and silver nanowire electrodes by using selective oxygen plasma treatment method without photolithography and etching processes. Differently from the conventional single-capacitor multi-functional sensors, our new multi-functional sensor is composed of two vertically-stacked capacitors (dual-capacitor). The unique dual-capacitor structure can detect the type and strength of external stimuli including curvature, pressure, strain, and touch with clear distinction, and it can also detect the surface-normal directionality of curvature, pressure, and touch. Meanwhile, the conventional single-capacitor sensor has ambiguity in distinguishing curvature and pressure and it can detect only the strength of external stimulus. The type, directionality, and strength of external stimulus can be determined based on the relative capacitance changes of the two stacked capacitors. Additionally, the logical flow reflected on a tree structure with its branches reaching the direction and strength of the corresponding external stimulus unambiguously is devised. This logical flow can be readily implemented in the sensor driving circuit if the dual-capacitor sensor is commercialized actually in the future.

  11. A dual-mode proximity sensor with integrated capacitive and temperature sensing units

    International Nuclear Information System (INIS)

    Qiu, Shihua; Huang, Ying; He, Xiaoyue; Sun, Zhiguang; Liu, Ping; Liu, Caixia

    2015-01-01

    The proximity sensor is one of the most important devices in the field of robot application. It can accurately provide the proximity information to assistant robots to interact with human beings and the external environment safely. In this paper, we have proposed and demonstrated a dual-mode proximity sensor composed of capacitive and resistive sensing units. We defined the capacitive type proximity sensor perceiving the proximity information as C-mode and the resistive type proximity sensor detecting as R-mode. Graphene nanoplatelets (GNPs) were chosen as the R-mode sensing material because of its high performance. The dual-mode proximity sensor presents the following features: (1) the sensing distance of the dual-mode proximity sensor has been enlarged compared with the single capacitive proximity sensor in the same geometrical pattern; (2) experiments have verified that the proposed sensor can sense the proximity information of different materials; (3) the proximity sensing capability of the sensor has been improved by two modes perceive collaboratively, for a plastic block at a temperature of 60 °C: the R-mode will perceive the proximity information when the distance d between the sensor and object is 6.0–17.0 mm and the C-mode will do that when their interval is 0–2.0 mm; additionally two modes will work together when the distance is 2.0–6.0 mm. These features indicate our transducer is very valuable in skin-like sensing applications. (paper)

  12. Standard guide for fretting fatigue testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide defines terminology and covers general requirements for conducting fretting fatigue tests and reporting the results. It describes the general types of fretting fatigue tests and provides some suggestions on developing and conducting fretting fatigue test programs. 1.2 Fretting fatigue tests are designed to determine the effects of mechanical and environmental parameters on the fretting fatigue behavior of metallic materials. This guide is not intended to establish preference of one apparatus or specimen design over others, but will establish guidelines for adherence in the design, calibration, and use of fretting fatigue apparatus and recommend the means to collect, record, and reporting of the data. 1.3 The number of cycles to form a fretting fatigue crack is dependent on both the material of the fatigue specimen and fretting pad, the geometry of contact between the two, and the method by which the loading and displacement are imposed. Similar to wear behavior of materials, it is important t...

  13. Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors.

    Science.gov (United States)

    Ha, Keum-Won; Lee, Jeong-Yun; Kim, Jeong-Geun; Baek, Donghyun

    2018-04-01

    Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW) radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW) radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO) is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL) is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG) block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs), the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor.

  14. Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors

    Directory of Open Access Journals (Sweden)

    Keum-Won Ha

    2018-04-01

    Full Text Available Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs, the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor.

  15. Understanding and modeling Förster-type resonance energy transfer (FRET) introduction to FRET

    CERN Document Server

    Govorov, Alexander; Demir, Hilmi Volkan

    2016-01-01

    This Brief presents a historical overview of the Förster-type nonradiative energy transfer and a compilation of important progress in FRET research, starting from Förster until today, along with a summary of the current state-of-the-art. Here the objective is to provide the reader with a complete account of important milestones in FRET studies and FRET applications as well as a picture of the current status.

  16. EXPERIMENTAL INVESTIGTION OF THE FRETTING PHENOMENON

    Directory of Open Access Journals (Sweden)

    Ştefan GHIMISI

    2015-12-01

    Full Text Available Fretting is now fully identified as a small amplitude oscilatory motion which induces a harmonic tangential force between two surfaces in contact.It is related to three main loadings, i.e. fretting-wear, fretting-fatigue and fretting corrosion.Fretting regimes were first mapped by Vingsbo. In a similar way, three fretting regimes will be considered: stick regime,slip regime and mixed regime. The mixed regime was made up of initial gross slip followed by partial slip condition after a few hundred cycles. Obviously the partial slip transition develops the highest stress levels which can induce fatigue crack nucleation depending on the fatigue properties of the two contacting first bodies. Therefore prediction of the frontier between partial slip and gross slip is required.

  17. Medical diagnosis and remote sensing at fiber-tip: picosecond resolved FRET sensor

    Science.gov (United States)

    Polley, Nabarun; Pal, Samir Kumar

    2016-03-01

    Förster Resonance Energy Transfer (FRET) strategy in popular in fiber-optic sensing. However, the steady state emission quenching of the donor is inadequate to conclude FRET. The resonance type energy transfer from one molecule (donor) to other (acceptor) should meet few key properties including donor to acceptor energy migration in non-radiative way. In the present study, we have coupled the evanescent field of an optical fiber to the covalently attached donor (dansyl) molecules at the fiber tip. By using picosecond resolved time correlated single photon counting (TCSPC) we have demonstrated that dansyl at the fiber tip transfers energy to a well known DNA-intercalating dye ethidium. Our ultrafast detection scheme selectively distinguishes the probe (dansyl) emission from the intrinsic emission of the fiber. We have also used the setup for the remote sensing of the dielectric constant (polarity) of an environment. We have finally implemented the detection mechanism to detect an industrial synthetic dye methylene blue (MB) in water.

  18. A Three-Axis Force Sensor for Dual Finger Haptic Interfaces

    OpenAIRE

    Fontana, Marco; Marcheschi, Simone; Salsedo, Fabio; Bergamasco, Massimo

    2012-01-01

    In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force an...

  19. Note: A dual-channel sensor for dew point measurement based on quartz crystal microbalance

    Science.gov (United States)

    Li, Ning; Meng, Xiaofeng; Nie, Jing

    2017-05-01

    A new sensor with dual-channel was designed for eliminating the temperature effect on the frequency measurement of the quartz crystal microbalance (QCM) in dew point detection. The sensor uses active temperature control, produces condensation on the surface of QCM, and then detects the dew point. Both the single-channel and the dual-channel methods were conducted based on the device. The measurement error of the single-channel method was less than 0.5 °C at the dew point range of -2 °C-10 °C while the dual-channel was 0.3 °C. The results showed that the dual-channel method was able to eliminate the temperature effect and yield better measurement accuracy.

  20. Characteristic of fretting damage in metal material

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Zhi, F.

    1988-10-01

    The fretting fatigue experiment of LC4 high strength aluminum alloy is described. An SEM examination of the fractology and morphology of fretting damage is carried out as well as an EDAX analysis of the chemical composition of fretting particles. The results show that many loose oxide particles were produced and accumulated in the fretting damage region. 10 references.

  1. Bioinspired Flexible and Highly Responsive Dual-Mode Strain/Magnetism Composite Sensor.

    Science.gov (United States)

    Huang, Pei; Li, Yuan-Qing; Yu, Xiao-Guang; Zhu, Wei-Bin; Nie, Shu-Yan; Zhang, Hao; Liu, Jin-Rui; Hu, Ning; Fu, Shao-Yun

    2018-04-04

    The mimicry of human skin to detect both oncoming and physical-contacting object is of great importance in the fields of manufacturing, artificial robots and vehicles, etc. Herein, a novel bioinspired flexible and highly responsive dual-mode strain/magnetism composite sensor, which works via both contact and contactless modes, is first fabricated by incorporating Fe 3 O 4 /silicone system into a carbon fiber aerogel (CFA). The distance dependence of magnetic field endorses the CFA/Fe 3 O 4 /silicone composite possible for spatial sensing due to the introduction of Fe 3 O 4 magnetic nanoparticles. As a result, the as-prepared flexible sensor exhibits precise and real-time response not only to direct-contact compression as usual but also to contactless magnetic field in a wide frequency range from 0.1 to 10 Hz, achieving the maximum variance of 68% and 86% in relative electrical resistance, respectively. The contact and contactless sensing modes of the strain/magnetism sensor are clearly demonstrated by recording the speeds of bicycle riding and walking, respectively. Interestingly, this dual-mode composite sensor exhibits the capacity of identifying the contact and contactless state, which is the first report for flexible sensors. The current protocol is eco-friendly, facile, and thought-provoking for the fabrication of multifunctional sensors.

  2. FRET Sensor for Erythrosine Dye Based on Organic Nanoparticles: Application to Analysis of Food Stuff.

    Science.gov (United States)

    Mahajan, Prasad G; Bhopate, Dhanaji P; Kolekar, Govind B; Patil, Shivajirao R

    2016-07-01

    An aqueous suspension of fluorescent nanoparticles (PHNNPs) of naphthol based fluorescent organic compound 1-[(Z)-(2-phenylhydrazinylidene) methyl] naphthalene -2-ol (PHN) were prepared using reprecipitation method shows bathochromically shifted aggregation induced enhanced emission (AIEE) in the spectral region where erythrosine (ETS) food dye absorbs strongly. The average size of 72.6 nm of aqueous suspension of PHNNPs obtained by Dynamic light scattering results shows a narrow particle size distribution. The negative zeta potential of nano probe (-22.6 mV) responsible to adsorb oppositely charged analyte on its surface and further permit to bind nano probe and analyte within the close distance proximity required for efficient fluorescence resonance energy transfer (FRET) to take place from donor (PHNNPs) to acceptor (ETS). Systematic FRET experiments performed by measuring fluorescence quenching of PHNNPs with successive addition of ETS solution exploited the use of the PHNNPs as a novel nano probe for the detection of ETS in aqueous solution with extremely lower limit of detection equal to 3.6 nM (3.1 ng/mL). The estimation of photo kinetic and thermodynamic parameters such as quenching rate constant, enthalpy change (∆H), Gibbs free energy change (∆G) and entropy change (∆S) was obtained by the quenching results obtained at different constant temperatures which were found to fit the well-known Stern-Volmer relation. The mechanism of binding and fluorescence quenching of PHNNPs by ETS food dye is proposed on the basis of results obtained in photophysical studies, thermodynamic parameter, energy transfer efficiency, critical energy transfer distance (R0) and distance of approach between donor-acceptor molecules (r). The proposed FRET method based on fluorescence quenching of PHNNPs was successfully applied to develop an analytical method for estimation of ETS from food stuffs without interference of other complex ingredients. Graphical Abstract A

  3. FRET two-hybrid assay by linearly fitting FRET efficiency to concentration ratio between acceptor and donor

    Science.gov (United States)

    Du, Mengyan; Yang, Fangfang; Mai, Zihao; Qu, Wenfeng; Lin, Fangrui; Wei, Lichun; Chen, Tongsheng

    2018-04-01

    We here introduce a fluorescence resonance energy transfer (FRET) two-hybrid assay method to measure the maximal donor(D)- and acceptor(A)-centric FRET efficiency (ED,max and EA,max) of the D-A complex and its stoichiometry by linearly fitting the donor-centric FRET efficiency (ED) to the acceptor-to-donor concentration ratio (RC) and acceptor-centric FRET efficiency (EA) to 1/RC, respectively. We performed this method on a wide-field fluorescence microscope for living HepG2 cells co-expressing FRET tandem constructs and free donor/acceptor and obtained correct ED, EA, and stoichiometry values of those tandem constructs. Evaluation on the binding of Bad with Bcl-XL in Hela cells showed that Bad interacted strongly with Bcl-XL to form a Bad-Bcl-XL complex on mitochondria, and one Bad interacted mainly with one Bcl-XL molecule in healthy cells, while with multiple (maybe 2) Bcl-XL molecules in apoptotic cells.

  4. Stuy on Fatigue Life of Aluminum Alloy Considering Fretting

    Science.gov (United States)

    Yang, Maosheng; Zhao, Hongqiang; Wang, Yunxiang; Chen, Xiaofei; Fan, Jiali

    2018-01-01

    To study the influence of fretting on Aluminum Alloy, a global finite element model considering fretting was performed using the commercial code ABAQUS. With which a new model for predicting fretting fatigue life has been presented based on friction work. The rationality and effectiveness of the model were validated according to the contrast of experiment life and predicting life. At last influence factor on fretting fatigue life of aerial aluminum alloy was investigated with the model. The results revealed that fretting fatigue life decreased monotonously with the increasing of normal load and then became constant at higher pressures. At low normal load, fretting fatigue life was found to increase with increase in the pad radius. At high normal load, however, the fretting fatigue life remained almost unchanged with changes in the fretting pad radius. The bulk stress amplitude had the dominant effect on fretting fatigue life. The fretting fatigue life diminished as the bulk stress amplitude increased.

  5. Distributed dual-parameter optical fiber sensor based on cascaded microfiber Fabry-Pérot interferometers

    Science.gov (United States)

    Xiang, Yang; Luo, Yiyang; Zhang, Wei; Liu, Deming; Sun, Qizhen

    2017-04-01

    We propose and demonstrate a distributed fiber sensor based on cascaded microfiber Fabry-Perot interferometers (MFPI) for simultaneous refractive index (SRI) and temperature measurement. By employing MFPI which is fabricated by taper-drawing the center of a uniform fiber Bragg grating (FBG) on standard fiber into a section of microfiber, dual parameters including SRI and temperature can be detected through demodulating the reflection spectrum of the MFPI. Further, wavelength-division-multiplexing (WDM) is applied to realize distributed dual-parameter fiber sensor by using cascaded MFPIs with different Bragg wavelengths. A prototype sensor system with 5 cascaded MFPIs is constructed to experimentally demonstrate the sensing performance.

  6. Single cell FRET analysis for the identification of optimal FRET-pairs in Bacillus subtilis using a prototype MEM-FLIM system.

    Directory of Open Access Journals (Sweden)

    Ruud G J Detert Oude Weme

    Full Text Available Protein-protein interactions can be studied in vitro, e.g. with bacterial or yeast two-hybrid systems or surface plasmon resonance. In contrast to in vitro techniques, in vivo studies of protein-protein interactions allow examination of spatial and temporal behavior of such interactions in their native environment. One approach to study protein-protein interactions in vivo is via Förster Resonance Energy Transfer (FRET. Here, FRET efficiency of selected FRET-pairs was studied at the single cell level using sensitized emission and Frequency Domain-Fluorescence Lifetime Imaging Microscopy (FD-FLIM. For FRET-FLIM, a prototype Modulated Electron-Multiplied FLIM system was used, which is, to the best of our knowledge, the first account of Frequency Domain FLIM to analyze FRET in single bacterial cells. To perform FRET-FLIM, we first determined and benchmarked the best fluorescent protein-pair for FRET in Bacillus subtilis using a novel BglBrick-compatible integration vector. We show that GFP-tagRFP is an excellent donor-acceptor pair for B. subtilis in vivo FRET studies. As a proof of concept, selected donor and acceptor fluorescent proteins were fused using a linker that contained a tobacco etch virus (TEV-protease recognition sequence. Induction of TEV-protease results in loss of FRET efficiency and increase in fluorescence lifetime. The loss of FRET efficiency after TEV induction can be followed in time in single cells via time-lapse microscopy. This work will facilitate future studies of in vivo dynamics of protein complexes in single B. subtilis cells.

  7. A flexible dual-mode proximity sensor based on cooperative sensing for robot skin applications

    Science.gov (United States)

    Huang, Ying; Cai, Xia; Kan, Wenqing; Qiu, Shihua; Guo, Xiaohui; Liu, Caixia; Liu, Ping

    2017-08-01

    A flexible dual-mode proximity sensor has been designed and implemented, which is capable of combining capacitive-resistive detection in this paper. The capacitive type proximity sensor detecting is defined as mode-C, and the resistive type proximity sensor detecting is defined as mode-R. The characteristics of the proximity sensor are as follows: (1) the theoretical mode is developed which indicates that this proximity sensor can reflect proximity information accurately; (2) both sensing modes are vertically integrated into a sandwich-like chip with an 8 mm × 12 mm unit area. The thickness of a mode-R sensing material (graphene nanoplatelets) and mode-C dielectric (the mixture of carbon black and silicone rubber) is 1 mm and 2.5 mm, respectively; (3) for mode-R, the linearity of temperature-resistance curve can achieve 0.998 in the temperature range from 25°C to 65°C. And for mode-C, various materials can be successfully detected with fast response and high reversibility. Meanwhile, the study compensated the influence of object temperature to ensure mode-C properly works. A cooperative sensing test shows that R-C dual modes sense effectively which can enlarge the sensing distance compared with the single mode proximity sensor. The fabrication of this sensor is convenient, and the integrity of a flexible sandwich-like structure based on dual modes is beneficial to form arrays, which is suitable to be used in skin-like sensing applications.

  8. Dual cameras acquisition and display system of retina-like sensor camera and rectangular sensor camera

    Science.gov (United States)

    Cao, Nan; Cao, Fengmei; Lin, Yabin; Bai, Tingzhu; Song, Shengyu

    2015-04-01

    For a new kind of retina-like senor camera and a traditional rectangular sensor camera, dual cameras acquisition and display system need to be built. We introduce the principle and the development of retina-like senor. Image coordinates transformation and interpolation based on sub-pixel interpolation need to be realized for our retina-like sensor's special pixels distribution. The hardware platform is composed of retina-like senor camera, rectangular sensor camera, image grabber and PC. Combined the MIL and OpenCV library, the software program is composed in VC++ on VS 2010. Experience results show that the system can realizes two cameras' acquisition and display.

  9. A plastic optical fiber sensor for the dual sensing of temperature and oxygen

    Science.gov (United States)

    Lo, Yu-Lung; Chu, Chen-Shane

    2008-04-01

    This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

  10. Efficient FRET-based fuorescent ratiometric chemosensors for Fe3+ and its application in living cells

    International Nuclear Information System (INIS)

    Wang, Cuicui; Liu, Yaqi; Cheng, Junye; Song, Jianhua; Zhao, Yufen; Ye, Yong

    2015-01-01

    A series of novel FRET-based fluorescent ratiometric chemosensors (L 1 –L 6 ) were designed and synthesized. Sensor L 2 showed reversible and the best selective recognition toward Fe 3+ over other metal ions with a detection limit of 0.418 ppm, which can meet the selective requirements for practical application. Experiment results showed that the response behavior of L 2 toward Fe 3+ is pH independent in weak acid condition (pH 4.0–6.0). In addition, sensor L 2 was successfully applied for ratiometric visualization of Fe 3+ in living cells. - Highlights: • The detection limit of a new FRET probe for Fe 3+ was 0.418 ppm. • The probe exhibited high selectivity and sensitivity detection to Fe 3+ with a pH span of 4.0–6.0. • The significant changes in color could be used for naked-eye detection • The fluorescence imaging experiment demonstrated its value of practical application

  11. In vivo dynamics of enterovirus protease revealed by fluorescence resonance emission transfer (FRET) based on a novel FRET pair

    International Nuclear Information System (INIS)

    Hsu, Y.-Y.; Liu, Y.-N.; Wang Wenyen; Kao, Fu-Jen; Kung, S.-H.

    2007-01-01

    An in vivo protease assay suitable for analysis by fluorescence resonance energy transfer (FRET) was developed on the basis of a novel FRET pair. The specifically designed fusion substrate consists of green fluorescent protein 2 (GFP 2 )-peptide-red fluorescent protein 2 (DsRed2), with a cleavage motif for the enterovirus 2A protease (2A pro ) embedded within the peptide region. FRET can be readily visualized in real-time from cells expressing the fusion substrate until a proteolytic cleavage by 2A pro from the input virus. The level of FRET decay is a function of the amount and infection duration of the inoculated virus as measured by a fluorometer assay. The FRET biosensor also responded well to other related enteroviruses but not to a phylogenetically distant virus. Western blot analysis confirmed the physical cleavage of the fusion substrate upon the infections. The study provides proof of principle for applying the FRET technology to diagnostics, screening procedures, and cell biological research

  12. NIR FRET Fluorophores for Use as an Implantable Glucose Biosensor

    Directory of Open Access Journals (Sweden)

    Majed DWEIK

    2008-12-01

    Full Text Available Development of an in vivo optical sensor requires the utilization of Near Infra Red (NIR fluorophores due to their ability to operate within the biological tissue window. Alexa Fluor 750 (AF750 and Alexa Fluor 680 (AF680 were examined as potential NIR fluorophores for an in vivo fluorescence resonance energy transfer (FRET glucose biosensor. AF680 and AF750 found to be a FRET pair and percent energy transfer was calculated. Next, the tested dye pair was utilized in a competitive binding assay in order to detect glucose. Concanavalin A (Con A and dextran have binding affinity, but in the presence of glucose, glucose displaces dextran due to its higher affinity to Con A than dextran. Finally, the percent signal transfer through porcine skin was examined. The results showed with approximately 4.0 mm porcine skin thickness, 1.98 % of the fluorescence was transmitted and captured by the detector.

  13. SPHERICAL COVERAGE DUAL MODE SENSOR FOR UAS SEPARATION ASSURANCE, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Proposed is a dual-mode sensor for use aboard unmanned aircraft for safe operation in the NAS that: 1. Incorporates high resolution Millimeter Wave radar with high...

  14. The Z-cad dual fluorescent sensor detects dynamic changes between the epithelial and mesenchymal cellular states.

    Science.gov (United States)

    Toneff, M J; Sreekumar, A; Tinnirello, A; Hollander, P Den; Habib, S; Li, S; Ellis, M J; Xin, L; Mani, S A; Rosen, J M

    2016-06-17

    The epithelial to mesenchymal transition (EMT) has been implicated in metastasis and therapy resistance of carcinomas and can endow cancer cells with cancer stem cell (CSC) properties. The ability to detect cancer cells that are undergoing or have completed EMT has typically relied on the expression of cell surface antigens that correlate with an EMT/CSC phenotype. Alternatively these cells may be permanently marked through Cre-mediated recombination or through immunostaining of fixed cells. The EMT process is dynamic, and these existing methods cannot reveal such changes within live cells. The development of fluorescent sensors that mirror the dynamic EMT state by following the expression of bona fide EMT regulators in live cells would provide a valuable new tool for characterizing EMT. In addition, these sensors will allow direct observation of cellular plasticity with respect to the epithelial/mesenchymal state to enable more effective studies of EMT in cancer and development. We generated a lentiviral-based, dual fluorescent reporter system, designated as the Z-cad dual sensor, comprising destabilized green fluorescent protein containing the ZEB1 3' UTR and red fluorescent protein driven by the E-cadherin (CDH1) promoter. Using this sensor, we robustly detected EMT and mesenchymal to epithelial transition (MET) in breast cancer cells by flow cytometry and fluorescence microscopy. Importantly, we observed dynamic changes in cellular populations undergoing MET. Additionally, we used the Z-cad sensor to identify and isolate minor subpopulations of cells displaying mesenchymal properties within a population comprising predominately epithelial-like cells. The Z-cad dual sensor identified cells with CSC-like properties more effectively than either the ZEB1 3' UTR or E-cadherin sensor alone. The Z-cad dual sensor effectively reports the activities of two factors critical in determining the epithelial/mesenchymal state of carcinoma cells. The ability of this stably

  15. A Dual-Mode Large-Arrayed CMOS ISFET Sensor for Accurate and High-Throughput pH Sensing in Biomedical Diagnosis.

    Science.gov (United States)

    Huang, Xiwei; Yu, Hao; Liu, Xu; Jiang, Yu; Yan, Mei; Wu, Dongping

    2015-09-01

    The existing ISFET-based DNA sequencing detects hydrogen ions released during the polymerization of DNA strands on microbeads, which are scattered into microwell array above the ISFET sensor with unknown distribution. However, false pH detection happens at empty microwells due to crosstalk from neighboring microbeads. In this paper, a dual-mode CMOS ISFET sensor is proposed to have accurate pH detection toward DNA sequencing. Dual-mode sensing, optical and chemical modes, is realized by integrating a CMOS image sensor (CIS) with ISFET pH sensor, and is fabricated in a standard 0.18-μm CIS process. With accurate determination of microbead physical locations with CIS pixel by contact imaging, the dual-mode sensor can correlate local pH for one DNA slice at one location-determined microbead, which can result in improved pH detection accuracy. Moreover, toward a high-throughput DNA sequencing, a correlated-double-sampling readout that supports large array for both modes is deployed to reduce pixel-to-pixel nonuniformity such as threshold voltage mismatch. The proposed CMOS dual-mode sensor is experimentally examined to show a well correlated pH map and optical image for microbeads with a pH sensitivity of 26.2 mV/pH, a fixed pattern noise (FPN) reduction from 4% to 0.3%, and a readout speed of 1200 frames/s. A dual-mode CMOS ISFET sensor with suppressed FPN for accurate large-arrayed pH sensing is proposed and demonstrated with state-of-the-art measured results toward accurate and high-throughput DNA sequencing. The developed dual-mode CMOS ISFET sensor has great potential for future personal genome diagnostics with high accuracy and low cost.

  16. Prediction of fretting fatigue behavior under elastic-plastic conditions

    International Nuclear Information System (INIS)

    Shin, Ki Su

    2009-01-01

    Fretting fatigue generally leads to the degradation of the fatigue strength of a material due to cyclic micro-slip between two contacting materials. Fretting fatigue is regarded as an important issue in designing aerospace structures. While many studies have evaluated fretting fatigue behavior under elastic deformation conditions, few have focused on fretting fatigue behavior under elastic-plastic deformation conditions, especially the crack orientation and fatigue life prediction for Ti-6Al-4V. The primary goal of this study was to characterize the fretting fatigue crack initiation behavior in the presence of plasticity. Experimental tests were performed using pad configurations involving elastic-plastic deformations. To calculate stress distributions under elastic-plastic fretting fatigue conditions, FEA was also performed. Several parametric approaches were used to predict fretting fatigue life along with stress distribution resulting from FEA. However, those parameters using surface stresses were unable to establish an equivalence between elastic fretting fatigue data and elastic-plastic fretting fatigue data. Based on this observation, the critical distance methods, which are commonly used in notch analysis, were applied to the fretting fatigue problem. In conclusion, the effective strain range method when used in conjunction with the SMSSR parameter showed a good correlation of data points between the pad configurations involving elastic and elastic plastic deformations

  17. Dual Resonant Frequencies Effects on an Induction-Based Oil Palm Fruit Sensor

    Directory of Open Access Journals (Sweden)

    Noor Hasmiza Harun

    2014-11-01

    Full Text Available As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB. Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB. A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA. To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept.

  18. Dual resonant frequencies effects on an induction-based oil palm fruit sensor.

    Science.gov (United States)

    Harun, Noor Hasmiza; Misron, Norhisam; Mohd Sidek, Roslina; Aris, Ishak; Wakiwaka, Hiroyuki; Tashiro, Kunihisa

    2014-11-19

    As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept.

  19. Dual door entry to exciplex emission in a chimeric DNA duplex containing non-nucleoside-nucleoside pair.

    Science.gov (United States)

    Bag, Subhendu Sekhar; Talukdar, Sangita; Kundu, Rajen; Saito, Isao; Jana, Subhashis

    2014-01-25

    Dual door entry to exciplex formation was established in a chimeric DNA duplex wherein a fluorescent non-nucleosidic base surrogate () is paired against a fluorescent nucleosidic base surrogate (). Packing of the nucleobases via intercalative stacking interactions led to an exciplex emission either via FRET from the donor or direct excitation of the FRET acceptor .

  20. A three-axis force sensor for dual finger haptic interfaces.

    Science.gov (United States)

    Fontana, Marco; Marcheschi, Simone; Salsedo, Fabio; Bergamasco, Massimo

    2012-10-10

    In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor.

  1. A Three-Axis Force Sensor for Dual Finger Haptic Interfaces

    Directory of Open Access Journals (Sweden)

    Fabio Salsedo

    2012-10-01

    Full Text Available In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor.

  2. Design and Optimization of Dual Optical Fiber MEMS Pressure Sensor For Biomedical Applications

    International Nuclear Information System (INIS)

    Dagang, Guo; Po, Samuel Ng Choon; Hock, Francis Tay Eng; Rongming, Lin

    2006-01-01

    A novel Single Deeply Corrugated Diaphragm (SDCD) based dual optical fiber Fabry-Perot pressure sensor for blood pressure measurement is proposed. Both mechanical and optical simulations are performed to demonstrate the feasibility and superior performance of the proposed sensor. Result shows that less than 2% nonlinearity can be achieved for the proposed sensor using optimal Fabry-Perot microcavity. Also, the fabrication process of the proposed sensor is given, instead of complicated fusion bonding process, only bulk and surface micromachining techniques are required which facilitate the mass production of such biocompatible and disposable pressure sensors

  3. Soluble polymeric dual sensor for temperature and pH value

    NARCIS (Netherlands)

    Pietsch, C.; Hoogenboom, R.; Schubert, U.S.

    2009-01-01

    Two birds with one stone: A thermoresponsive copolymer (see picture, blue beads) bearing a pH-responsive solvatochromic dye (red beads) acts as the first dual sensor for temperature and pH value (black curve). When the hydrophilicity of the copolymer is increased by using a monomer with more

  4. Applicability of out-of-pile fretting wear tests to in-reactor fretting wear-induced failure time prediction

    Science.gov (United States)

    Kim, Kyu-Tae

    2013-02-01

    In order to investigate whether or not the grid-to-rod fretting wear-induced fuel failure will occur for newly developed spacer grid spring designs for the fuel lifetime, out-of-pile fretting wear tests with one or two fuel assemblies are to be performed. In this study, the out-of-pile fretting wear tests were performed in order to compare the potential for wear-induced fuel failure in two newly-developed, Korean PWR spacer grid designs. Lasting 20 days, the tests simulated maximum grid-to-rod gap conditions and the worst flow induced vibration effects that might take place over the fuel life time. The fuel rod perforation times calculated from the out-of-pile tests are greater than 1933 days for 2 μm oxidized fuel rods with a 100 μm grid-to-rod gap, whereas those estimated from in-reactor fretting wear failure database may be about in the range of between 60 and 100 days. This large discrepancy in fuel rod perforation may occur due to irradiation-induced cladding oxide microstructure changes on the one hand and a temperature gradient-induced hydrogen content profile across the cladding metal region on the other hand, which may accelerate brittleness in the grid-contacting cladding oxide and metal regions during the reactor operation. A three-phase grid-to-rod fretting wear model is proposed to simulate in-reactor fretting wear progress into the cladding, considering the microstructure changes of the cladding oxide and the hydrogen content profile across the cladding metal region combined with the temperature gradient. The out-of-pile tests cannot be directly applicable to the prediction of in-reactor fretting wear-induced cladding perforations but they can be used only for evaluating a relative wear resistance of one grid design against the other grid design.

  5. Mechanisms of fretting-fatigue of titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Antoniou, R A; Radtke, T C [Defence Sci. and Technol. Organ., Melbourne, Vic. (Australia). Aeronautical and Maritime Res. Lab.

    1997-09-30

    The effect of continuous fretting in air at 20 C on fatigue performance has been studied for Ti-17 and Ti-6Al-4V, high strength titanium alloys used for gas-turbine fan and compressor disks and blades, respectively. The effect of fretting was to reduce the fatigue stress limit from 700 MPa for plain fatigue to 200 MPa for fretting-fatigue. A number of models, supported by metallographic and fractographic evidence, are proposed which explain (i) how the cyclic loading of individual asperities results in crack initiation; (ii) the formation of multiple cracks; (iii) the existence of non-propagating cracks; and (iv) how fretting influences crack propagation once fatigue cracks have formed. (orig.) 46 refs.

  6. A new trend to determine biochemical parameters by quantitative FRET assays.

    Science.gov (United States)

    Liao, Jia-yu; Song, Yang; Liu, Yan

    2015-12-01

    Förster resonance energy transfer (FRET) has been widely used in biological and biomedical research because it can determine molecule or particle interactions within a range of 1-10 nm. The sensitivity and efficiency of FRET strongly depend on the distance between the FRET donor and acceptor. Historically, FRET assays have been used to quantitatively deduce molecular distances. However, another major potential application of the FRET assay has not been fully exploited, that is, the use of FRET signals to quantitatively describe molecular interactive events. In this review, we discuss the use of quantitative FRET assays for the determination of biochemical parameters, such as the protein interaction dissociation constant (K(d)), enzymatic velocity (k(cat)) and K(m). We also describe fluorescent microscopy-based quantitative FRET assays for protein interaction affinity determination in cells as well as fluorimeter-based quantitative FRET assays for protein interaction and enzymatic parameter determination in solution.

  7. Stem Migration and Fretting Corrosion of the Antirotation Pin in the K2/Apex Hip System.

    Science.gov (United States)

    Kent, Michael; Edmondson, Mark; Ebert, Jay; Nivbrant, Nils; Kop, Alan; Wood, David; De Steiger, Richard

    2016-03-01

    Many exchangeable neck hip systems have been withdrawn because of fretting corrosion at the neck/stem coupling. Our prospective randomized study evaluating stem stability (Roentgen stereophotogrammetric analysis, dual-energy x-ray absorptiometry) and clinical outcomes between the K2/Apex hip systems was ceased early because of a withdrawal of the stems which had an unfavorably high early revision rate reported in the Australian Orthopaedic Association National Joint Registry (9.3% at 3 years). At 2 years, there are no clinical differences between the stems. Roentgen stereophotogrammetric analysis has identified a high proportion of potentially concerning subsidence and retroversion in both groups, more marked in the K2 stem, although mostly in asymptomatic patients. Dual-energy x-ray absorptiometry has shown similar bone density around the stems. Retrieval analysis of 3 study patients showed fretting corrosion of the antirotation pin and aseptic lymphocyte-dominated vasculitis-associated lesion, with no relationship to bearing type or size. Analysis of 7 further nonstudy K2/Apex stems confirmed similar corrosion. This study shows potentially concerning subsidence of both stems and is the first to describe corrosion at the neck-stem interface and a relationship to metal-related pathology. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  8. Development of dual sensor hand-held detector

    Science.gov (United States)

    Sezgin, Mehmet

    2010-04-01

    In this paper hand-held dual sensor detector development requirements are considered dedicated to buried object detection. Design characteristics of such a system are categorized and listed. Hardware and software structures, ergonomics, user interface, environmental and EMC/EMI tests to be applied and performance test issues are studied. Main properties of the developed system (SEZER) are presented, which contains Metal Detector (MD) and Ground Penetrating Radar (GPR). The realized system has ergonomic structure and can detect both metallic and non-metallic buried objects. Moreover classification of target is possible if it was defined to the signal processing software in learning phase.

  9. In-fiber torsion sensor based on dual polarized Mach-Zehnder interference.

    Science.gov (United States)

    Chen, Lei; Zhang, Wei-Gang; Wang, Li; Zhang, Hao; Sieg, Jonathan; Zhou, Quan; Zhang, Li-Yu; Wang, Biao; Yan, Tie-Yi

    2014-12-29

    This paper presents a novel optical fiber torsion sensor based on dual polarized Mach-Zehnder interference (DPMZI). Unlike the conventional fiber sensor, the proposed sensor is composed of a sensor part and a demodulator. The demodulator is made by a bared single mode fiber (SMF) loop, and the sensor part is a segment of a coated SMF placed before the loop. A mathematical model is proposed based on DPMZI mechanism and from the model when the sensor part is twisted, the E-field rotational angle will bring a quasi-linear impact on the resonance dip wavelength in their matched detecting range. A proof-of-concept experiment was performed to verify the theoretical prediction. From the experimental data, a sensitivity of -0.3703, -1.00962, and -0.59881 nm•m/rad is achieved with the determining range of 12.0936, 7.6959, and 10.4444 rad/m respectively. The sensor which is composed only of the SMF has the advantages of low insertion loss (~-2dB), healthy structure, low manufacture cost, and easy assembly and application.

  10. Quantitative multi-color FRET measurements by Fourier lifetime excitation-emission matrix spectroscopy

    Science.gov (United States)

    Zhao, Ming; Huang, Run; Peng, Leilei

    2012-01-01

    Förster resonant energy transfer (FRET) is extensively used to probe macromolecular interactions and conformation changes. The established FRET lifetime analysis method measures the FRET process through its effect on the donor lifetime. In this paper we present a method that directly probes the time-resolved FRET signal with frequency domain Fourier lifetime excitation-emission matrix (FLEEM) measurements. FLEEM separates fluorescent signals by their different phonon energy pathways from excitation to emission. The FRET process generates a unique signal channel that is initiated by donor excitation but ends with acceptor emission. Time-resolved analysis of the FRET EEM channel allows direct measurements on the FRET process, unaffected by free fluorophores that might be present in the sample. Together with time-resolved analysis on non-FRET channels, i.e. donor and acceptor EEM channels, time resolved EEM analysis allows precise quantification of FRET in the presence of free fluorophores. The method is extended to three-color FRET processes, where quantification with traditional methods remains challenging because of the significantly increased complexity in the three-way FRET interactions. We demonstrate the time-resolved EEM analysis method with quantification of three-color FRET in incompletely hybridized triple-labeled DNA oligonucleotides. Quantitative measurements of the three-color FRET process in triple-labeled dsDNA are obtained in the presence of free single-labeled ssDNA and double-labeled dsDNA. The results establish a quantification method for studying multi-color FRET between multiple macromolecules in biochemical equilibrium. PMID:23187535

  11. rFRET: A comprehensive, Matlab-based program for analyzing intensity-based ratiometric microscopic FRET experiments.

    Science.gov (United States)

    Nagy, Peter; Szabó, Ágnes; Váradi, Tímea; Kovács, Tamás; Batta, Gyula; Szöllősi, János

    2016-04-01

    Fluorescence or Förster resonance energy transfer (FRET) remains one of the most widely used methods for assessing protein clustering and conformation. Although it is a method with solid physical foundations, many applications of FRET fall short of providing quantitative results due to inappropriate calibration and controls. This shortcoming is especially valid for microscopy where currently available tools have limited or no capability at all to display parameter distributions or to perform gating. Since users of multiparameter flow cytometry usually apply these tools, the absence of these features in applications developed for microscopic FRET analysis is a significant limitation. Therefore, we developed a graphical user interface-controlled Matlab application for the evaluation of ratiometric, intensity-based microscopic FRET measurements. The program can calculate all the necessary overspill and spectroscopic correction factors and the FRET efficiency and it displays the results on histograms and dot plots. Gating on plots and mask images can be used to limit the calculation to certain parts of the image. It is an important feature of the program that the calculated parameters can be determined by regression methods, maximum likelihood estimation (MLE) and from summed intensities in addition to pixel-by-pixel evaluation. The confidence interval of calculated parameters can be estimated using parameter simulations if the approximate average number of detected photons is known. The program is not only user-friendly, but it provides rich output, it gives the user freedom to choose from different calculation modes and it gives insight into the reliability and distribution of the calculated parameters. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

  12. Optimum Layout for Sensors in Water Distribution Networks through Ant Colony Algorithm: A Dual Use Vision

    Directory of Open Access Journals (Sweden)

    Seyed Mehdi Miri

    2014-07-01

    Full Text Available The accidental or intentional entry of contaminants or self-deterioration of the water quality within the network itself can severely harm public health. Efficient water quality monitoring is one of the most important tools to guarantee a reliable potable water supply to consumers of drinking water distribution systems. Considering the high purchase, installation and maintenance cost of sensors in water distribution networks deploying two independent sensor networks within one distribution system is not only bounded by physical constraints but also is not a cost-effective approach. Therefore, need for combining different objectives and designing sensor network to simultaneity satisfying these objectives is felt. Sensors should comply with dual use benefits. Sensor locations and types should be integrated not only for achieving water security goals but also for accomplishing other water utility objectives, such as satisfying regulatory monitoring requirements or collecting information to solve water quality problems. In this study, a dual use vision for the sensor layout problem in the municipal water networks, is formulated and solved with the ant colony algorithm.

  13. Forster Resonance Energy Transfer (FRET) Analysis of Dual CFP/YFP Labeled AMPA Receptors Reveals Structural Rearrangement within the C-Terminal Domain during Receptor Activation

    DEFF Research Database (Denmark)

    Zachariassen, Linda Grønborg; Katchan, Mila; Plested, Andrew

    2014-01-01

    that retain function and display intrareceptor FRET. This includes a construct (GluA2-6Y-10C) containing YFP in the intracellular loop between the M1 and M2 membrane-embedded segments and CFP inserted in the C-ter- minal domain (CTD). GluA2-6Y-10C displays FRET with an efficiency of 0.11 while retaining wild......-type receptor expression and kinetic properties. We have used GluA2-6Y-10C to study conformational changes in homomeric GluA2 receptors during receptor activation. Our results show that the FRET efficiency is dependent on functional state of GluA2-6Y-10C and hereby indi- cates that the intracellular CTD...

  14. Dual-Mode Gas Sensor Composed of a Silicon Nanoribbon Field Effect Transistor and a Bulk Acoustic Wave Resonator: A Case Study in Freons

    Directory of Open Access Journals (Sweden)

    Ye Chang

    2018-01-01

    Full Text Available In this paper, we develop a novel dual-mode gas sensor system which comprises a silicon nanoribbon field effect transistor (Si-NR FET and a film bulk acoustic resonator (FBAR. We investigate their sensing characteristics using polar and nonpolar organic compounds, and demonstrate that polarity has a significant effect on the response of the Si-NR FET sensor, and only a minor effect on the FBAR sensor. In this dual-mode system, qualitative discrimination can be achieved by analyzing polarity with the Si-NR FET and quantitative concentration information can be obtained using a polymer-coated FBAR with a detection limit at the ppm level. The complementary performance of the sensing elements provides higher analytical efficiency. Additionally, a dual mixture of two types of freons (CFC-113 and HCFC-141b is further analyzed with the dual-mode gas sensor. Owing to the small size and complementary metal-oxide semiconductor (CMOS-compatibility of the system, the dual-mode gas sensor shows potential as a portable integrated sensing system for the analysis of gas mixtures in the future.

  15. Probing protein-lipid interactions by FRET between membrane fluorophores

    Science.gov (United States)

    Trusova, Valeriya M.; Gorbenko, Galyna P.; Deligeorgiev, Todor; Gadjev, Nikolai

    2016-09-01

    Förster resonance energy transfer (FRET) is a powerful fluorescence technique that has found numerous applications in medicine and biology. One area where FRET proved to be especially informative involves the intermolecular interactions in biological membranes. The present study was focused on developing and verifying a Monte-Carlo approach to analyzing the results of FRET between the membrane-bound fluorophores. This approach was employed to quantify FRET from benzanthrone dye ABM to squaraine dye SQ-1 in the model protein-lipid system containing a polycationic globular protein lysozyme and negatively charged lipid vesicles composed of phosphatidylcholine and phosphatidylglycerol. It was found that acceptor redistribution between the lipid bilayer and protein binding sites resulted in the decrease of FRET efficiency. Quantification of this effect in terms of the proposed methodology yielded both structural and binding parameters of lysozyme-lipid complexes.

  16. Nuclear Fuel Fretting Mechanisms in a Room Temperature Unlubricated Condition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Kim, Hyung Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-10-15

    Recently, efforts for evaluating the fretting wear mechanism have been carried out by many researchers in various conditions. In an unlubricated condition, especially, effects of a wear debris and/or its layer on the fretting wear behavior were proposed that the formation of a well-developed glaze layer has a beneficial effect for decreasing a friction coefficient. Otherwise, a wear rate was accelerated by a third-body abrasion. At this time, it is well known that wear debris behaviors are affected by test variables such as a temperature, environment, material characteristics, etc. In a nuclear fuel fretting, however, its contact condition is quite different when compared with general fretting wear studies and could be summarized as the following; first, a fuel rod is supported by spacer grid springs and dimples that were elastically deformable. This results in a unique friction loop and a different fretting mechanism when a fuel rod is vibrated due to a flow-induced vibration (FIV). Next, it is possible that some region of the wear scar area with a specific spring shape condition could be hidden due to different wear debris behavior. So, some of the wear debris layers could be found on the worn surfaces in previous studies even though fretting wear tests were performed in a water lubricated condition. Finally, initial contact condition could be changed both an actual operating condition in power plants (i.e. high temperature and pressurized water (HTHP) under severe irradiation conditions) and the fretting wear tests for evaluating the wear resistant spring in lab conditions (i.e. from room temperature to HTHP without irradiation conditions) due to material degradations and the formation of the wear scar, respectively. In summary, the spring shape effect and the variation of the contact condition with increasing fretting cycle should be evaluated in order to improve the wear resistance of the spacer grid spring. So, in this study, fretting wear tests have been

  17. Intercalating dye as an acceptor in quantum-dot-mediated FRET

    International Nuclear Information System (INIS)

    Lim, Teck Chuan; Bailey, Vasudev J; Wang, T-H; Ho, Y-P

    2008-01-01

    Fluorescence resonance energy transfer (FRET) is a popular tool to study intermolecular distances and characterize structural or conformational changes of biological macromolecules. We investigate a novel inorganic/organic FRET pair with quantum dots (QDs) as donors and DNA intercalating dyes, BOBO-3, as acceptors by using DNA as a linker. Typically, FRET efficiency increases with the number of stained DNA linked to a QD. However, with the use of intercalating dyes, we demonstrate that FRET efficiency at a fixed DNA:QD ratio can be further enhanced by increasing the number of dyes stained to a DNA strand through the use of an increased staining dye/bp ratio. We exploit this flexibility in the staining ratio to maintain a high FRET efficiency of >0.90 despite a sixfold decrease in DNA concentration. Having characterized this new QD-mediated FRET system, we test this system in a cellular environment using nanocomplexes generated by encapsulating DNA with commercial non-viral gene carriers. Using this novel FRET pair, we are able to monitor the configuration changes and fate of the DNA nanocomplexes during intracellular delivery, thereby providing an insight into the mechanistic study of gene delivery

  18. The Leakage determination on corrosion fretting machine

    International Nuclear Information System (INIS)

    Sriyono; Satmoko, Ari; Hafid, Abdul; Febrianto; Prasetio, Joko; Abtokhi; Sumarno, Edy; Handoyo, Ismu; Hidayati, Nur Rahmah; Histori

    1998-01-01

    Fretting machine is an experimental loop to learn fretting corrosion phenomena wich is caused by loading and vibration. On the steam generator, one of the corrosion process that's occurred, it can be caused by vibration between tubes and bending material. Because of high flow rate inside the tube, the high frequency vibration will appeared so it can make the corrosion on bending material more faster. This process can be simulate by fretting machine. This machine has already damage because of leakage. So it will be repaired by dismantling, radiography testing and redrawing. from the result of radiography, the leakage is caused by cracking on bellows seals of the dynamic main support

  19. Wide-beam sensors for controlling dual-delay systems

    Science.gov (United States)

    Edwards, J. B.; Twemlow, J. K.

    1982-09-01

    A class of dual delay feedback systems of open loop transfer function G(s) = k exp(-Xs)/l - exp(-Ws) is shown to be unstable if ratio X/W is noninteger. By means of z-transform techniques it is shown that, by using a feedback transducer that senses over a substantial distance either side of its central axis, closed-loop stability may be restored. Such transducers, termed widebeam sensors, include transmission, backscatter and natural radiation types as well as electromechanical conveyor belt weighers. Designing transducers for very narrow beams may not be desirable from the overall system viewpoint.

  20. Multi step FRET among three laser dyes Pyrene, Acriflavine and Rhodamine B

    International Nuclear Information System (INIS)

    Saha, Jaba; Dey, Dibyendu; Roy, Arpan Datta; Bhattacharjee, D.; Hussain, Syed Arshad

    2016-01-01

    Fluorescence Resonance Energy Transfer (FRET) system using three dyes has been demonstrated. It has been observed that multi step energy transfer occurred from Pyrene to Rhodamine B via Acriflavine. Here Acriflavine acts as an antenna to receive energy from Pyrene and transfer the same to Rhodamine B. This multi step FRET system is advantageous compared to the conventional FRET as this can be used to study molecular level interaction beyond conventional FRET distance (1–10 nm) as well as studying multi-branched macromolecules. The introduction of clay enhances the FRET efficiencies among the dye pair, which is an advantage to make the multi step system more useful. Similar approach can be used for increasing FRET efficiencies by using other dyes. - Highlights: • Multi-step FRET occurred from Pyrene (Py) to Rhodamine B (RhB) via Acriflavine (Acf). • Acf acts as an antenna to receive energy from Py and to transfer energy to RhB. • Multi-step FRET can be used to study molecular level interaction beyond 1–10 nm. • Incorporation of nanoclay laponite enhances the energy transfer efficiency.

  1. Förster Resonance Energy Transfer (FRET as a Tool for Dissecting the Molecular Mechanisms for Maturation of the Shigella Type III Secretion Needle Tip Complex

    Directory of Open Access Journals (Sweden)

    William D. Picking

    2012-11-01

    Full Text Available Förster resonance energy transfer (FRET provides a powerful tool for monitoring intermolecular interactions and a sensitive technique for studying Å-level protein conformational changes. One system that has particularly benefited from the sensitivity and diversity of FRET measurements is the maturation of the Shigella type III secretion apparatus (T3SA needle tip complex. The Shigella T3SA delivers effector proteins into intestinal cells to promote bacterial invasion and spread. The T3SA is comprised of a basal body that spans the bacterial envelope and a needle with an exposed tip complex that matures in response to environmental stimuli. FRET measurements demonstrated bile salt binding by the nascent needle tip protein IpaD and also mapped resulting structural changes which led to the recruitment of the translocator IpaB. At the needle tip IpaB acts as a sensor for host cell contact but prior to secretion, it is stored as a heterodimeric complex with the chaperone IpgC. FRET analyses showed that chaperone binding to IpaB’s N-terminal domain causes a conformational change in the latter. These FRET analyses, with other biophysical methods, have been central to understanding T3SA maturation and will be highlighted, focusing on the details of the FRET measurements and the relevance to this particular system.

  2. a Study on the Fretting Fatigue Life of Zircaloy Alloys

    Science.gov (United States)

    Kwon, Jae-Do; Park, Dae-Kyu; Woo, Seung-Wan; Chai, Young-Suck

    Studies on the strength and fatigue life of machines and structures have been conducted in accordance with the development of modern industries. In particular, fine and repetitive cyclic damage occurring in contact regions has been known to have an impact on fretting fatigue fractures. The main component of zircaloy alloy is Zr, and it possesses good mechanical characteristics at high temperatures. This alloy is used in the fuel rod material of nuclear power plants because of its excellent resistance. In this paper, the effect of the fretting damage on the fatigue behavior of the zircaloy alloy is studied. Further, various types of mechanical tests such as tension and plain fatigue tests are performed. Fretting fatigue tests are performed with a flat-flat contact configuration using a bridge-type contact pad and plate-type specimen. Through these experiments, it is found that the fretting fatigue strength decreases by about 80% as compared to the plain fatigue strength. Oblique cracks are observed in the initial stage of the fretting fatigue, in which damaged areas are found. These results can be used as the basic data for the structural integrity evaluation of corrosion-resisting alloys considering the fretting damages.

  3. Understanding and modeling Förster-type resonance energy transfer (FRET)

    CERN Document Server

    Hernández Martínez, Pedro Ludwig; Demir, Hilmi Volkan

    2017-01-01

    This Brief presents a complete study of the generalized theory of Förster-type energy transfer in nanostructures with mixed dimensionality. Here the aim is to obtain a generalized theory of FRET including a comprehensive set of analytical equations for all combinations and configurations of nanostructures and deriving generic expressions for the dimensionality involved. In this brief, the modification of FRET mechanism with respect to the nanostructure serving as the donor vs. the acceptor will be included, focusing on the rate’s distance dependency and the role of the effective dielectric function in FRET, which will be a unique, useful source for those who study and model FRET.

  4. CONSIDERATIONS REGARDING THE FRETTING PHENOMENON USING LEAF SPRINGS

    Directory of Open Access Journals (Sweden)

    Stefan GHIMIȘI

    2015-05-01

    Full Text Available The fretting phenomenon represents particulary and complex form of wear who is; generaly, and/or weary of fretting who is produced on the load contact in a relative oscialatory movement lay small amplitude.A simultaneoustly applied tangential force and normal into contact appears a adhesion force

  5. Prediction of pressure tube fretting-wear damage due to fuel vibration

    International Nuclear Information System (INIS)

    Yetisir, M.; Fisher, N.J.

    1997-01-01

    Fretting marks between fuel bundle bearing pads and pressure tubes have been observed at the inlet end of some Darlington Nuclear Generating Station (NGS) and Bruce NGS fuel channels. The excitation mechanisms that lead to fretting are not fully understood. In this paper, the possibility of bearing pad-to-pressure tube fretting due to turbulence-induced motion of the fuel element is investigated. Numerical simulations indicate that this mechanism by itself is not likely to cause the level of fretting experienced in Darlington and Bruce NGSs. (orig.)

  6. A rhodamine–dansyl conjugate as a FRET based sensor for Fe{sup 3+} in the red spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Puhui, E-mail: pxie2007@yahoo.com.cn [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Guo, Fengqi, E-mail: fqguo@zzu.edu.cn [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xia, Ruirui; Wang, Yao [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Yao, Denghui [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Yang, Guoyu; Xie, Lixia [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China)

    2014-01-15

    A new fluorescent resonance energy transfer (FRET) based fluorescent probe (compound 1) containing a dansyl unit as a donor and rhodamine 101 as an acceptor was developed to detect Fe{sup 3+} from other transition metal ions through ratiometric sensing in organic-aqueous solutions. Fe{sup 3+} induced a ring-opening reaction of the spirolactam rhodamine moiety of 1 resulting in the formation of a fluorescent derivative that can serve as the FRET acceptor. Ratiometric sensing of Fe{sup 3+} was accomplished by plotting the fluorescence intensity ratio at 605 nm and 515 nm versus ferric ion concentration. The probe displayed a linear response to Fe{sup 3+} in the range of 5.5–25 μM with a detection limit of 0.64 μM. A 1:1 stoichiometry for the 1–Fe{sup 3+} complex was formed with an association constant of 1.74×10{sup 4} M{sup −1}. The probe also exhibited a large Stokes shift (225 nm) which can eliminate backscattering effects of excitation light. -- Highlights: • A new colorimetric and fluorescent “off–on” chemosensor for Fe{sup 3+} was synthesized. • It can respond to Fe{sup 3+} in the red spectral region based on a FRET mechanism. • Its ratiometric sensing for Fe{sup 3+} can be accomplished with a signal to noise ratio of 214. • The large Stokes shift (225 nm) can rule out the excitation backscattering effects.

  7. Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

    Science.gov (United States)

    Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

    2015-09-21

    Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

  8. Fluorescent "on-off-on" switching sensor based on CdTe quantum dots coupled with multiwalled carbon nanotubes@graphene oxide nanoribbons for simultaneous monitoring of dual foreign DNAs in transgenic soybean.

    Science.gov (United States)

    Li, Yaqi; Sun, Li; Qian, Jing; Long, Lingliang; Li, Henan; Liu, Qian; Cai, Jianrong; Wang, Kun

    2017-06-15

    With the increasing concern of potential health and environmental risk, it is essential to develop reliable methods for transgenic soybean detection. Herein, a simple, sensitive and selective assay was constructed based on homogeneous fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) and multiwalled carbon nanotubes@graphene oxide nanoribbons (MWCNTs@GONRs) to form the fluorescent "on-off-on" switching for simultaneous monitoring dual target DNAs of promoter cauliflower mosaic virus 35s (P35s) and terminator nopaline synthase (TNOS) from transgenic soybean. The capture DNAs were immobilized with corresponding QDs to obtain strong fluorescent signals (turning on). The strong π-π stacking interaction between single-stranded DNA (ssDNA) probes and MWCNTs@GONRs led to minimal background fluorescence due to the FRET process (turning off). The targets of P35s and TNOS were recognized by dual fluorescent probes to form double-stranded DNA (dsDNA) through the specific hybridization between target DNAs and ssDNA probes. And the dsDNA were released from the surface of MWCNTs@GONRs, which leaded the dual fluorescent probes to generate the strong fluorescent emissions (turning on). Therefore, this proposed homogeneous assay can be achieved to detect P35s and TNOS simultaneously by monitoring the relevant fluorescent emissions. Moreover, this assay can distinguish complementary and mismatched nucleic acid sequences with high sensitivity. The constructed approach has the potential to be a tool for daily detection of genetically modified organism with the merits of feasibility and reliability. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Steam generator fretting-wear damage: A summary of recent findings

    International Nuclear Information System (INIS)

    Guerout, F.M.; Fisher, N.J.

    1999-01-01

    Flow-induced vibration of steam generator (SG) tubes may sometimes result in fretting-wear damage at the tube-to-support locations. Fretting-wear damage predictions are largely based on experimental data obtained at representative test conditions. Fretting-wear of SG materials has been studied at the Chalk River Laboratories for two decades. Tests are conducted in fretting-wear test machines that simulate SG environmental conditions and tube-to-support dynamic interactions. A new high-temperature force and displacement measuring system was developed to monitor tube-to-support interaction (i.e., work-rate) at operating conditions. This improvement in experimental fretting-wear technology was used to perform a comprehensive study of the effect of various environment and design parameters on SG tube wear damage. This paper summarizes the results of tests performed over the past 4 yr to study the effect of temperature, water chemistry, support geometry, and tube material on fretting-wear. The results show a significant effect of temperature on tube wear damage. Therefore, fretting-wear tests must be performed at operating temperatures in order to be relevant. No significant effect of the type of water treatment on tube wear damage was observed. For predominantly impacting motion, the wear of SG tubes in contact with 410 stainless steel is similar regardless of whether Alloy 690 or Alloy 800 is used as tubing material or whether lattice bars or broached hole supports are used. Based on results presented in this paper, an average wear coefficient value is recommended that is used for the prediction of SG tube wear depth versus time

  10. Prediction of pressure tube fretting-wear damage due to fuel vibration

    Energy Technology Data Exchange (ETDEWEB)

    Yetisir, M; Fisher, N J [Atomic Energy of Canada Ltd., Chalk River, ON (Canada)

    1996-12-31

    Fretting marks between fuel bundle bearing pads and pressure tubes have been observed at the inlet end of some Darlington NGS (nuclear generating station) and Bruce NGS fuel channels. The excitation mechanisms that lead to fretting are not fully understood. In this paper, the possibility of bearing pad-to-pressure tube fretting due to turbulence-induced motion of the fuel element is investigated. Numerical simulations indicate that this mechanism by itself is not likely to cause the level of fretting experienced in Darlington and Bruce NGS`s (nuclear generating stations). (author). 12 refs., 2 tabs., 11 figs.

  11. A cell-surface-anchored ratiometric i-motif sensor for extracellular pH detection.

    Science.gov (United States)

    Ying, Le; Xie, Nuli; Yang, Yanjing; Yang, Xiaohai; Zhou, Qifeng; Yin, Bincheng; Huang, Jin; Wang, Kemin

    2016-06-14

    A FRET-based sensor is anchored on the cell surface through streptavidin-biotin interactions. Due to the excellent properties of the pH-sensitive i-motif structure, the sensor can detect extracellular pH with high sensitivity and excellent reversibility.

  12. Uncovering Aberrant Mutant PKA Function with Flow Cytometric FRET

    Directory of Open Access Journals (Sweden)

    Shin-Rong Lee

    2016-03-01

    Full Text Available Biology has been revolutionized by tools that allow the detection and characterization of protein-protein interactions (PPIs. Förster resonance energy transfer (FRET-based methods have become particularly attractive as they allow quantitative studies of PPIs within the convenient and relevant context of living cells. We describe here an approach that allows the rapid construction of live-cell FRET-based binding curves using a commercially available flow cytometer. We illustrate a simple method for absolutely calibrating the cytometer, validating our binding assay against the gold standard isothermal calorimetry (ITC, and using flow cytometric FRET to uncover the structural and functional effects of the Cushing-syndrome-causing mutation (L206R on PKA’s catalytic subunit. We discover that this mutation not only differentially affects PKAcat’s binding to its multiple partners but also impacts its rate of catalysis. These findings improve our mechanistic understanding of this disease-causing mutation, while illustrating the simplicity, general applicability, and power of flow cytometric FRET.

  13. A Study on Fretting Behavior in Room Temperature for Inconel Alloy 690

    Science.gov (United States)

    Kwon, Jae Do; Chai, Young Suck; Bae, Yong Tak; Choi, Sung Jong

    The initial crack under fretting condition occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. The fretting damage, for example, can be observed in fossil and nuclear power plant, aircraft, automobile and petroleum chemical plants etc. INCONEL alloy 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the industries of nuclear power, chemicals, heat-treatment and electronics. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 690 was studied. Also, various kinds of tests on mechanical properties such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with flat-flat contact configuration using a bridge type contact pad and plate type specimen. Through these experiments, it is found that the fretting fatigue strength decreased about 43% compared to the plain fatigue strength. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks are initiated at an earlier stage. These results can be used as the basic data in a structural integrity evaluation of heat and corrosion resistant alloy considering fretting damages.

  14. Fuel bundle to pressure tube fretting in Bruce and Darlington

    Energy Technology Data Exchange (ETDEWEB)

    Norsworthy, A G; Ditschun, A [Atomic Energy of Canada Ltd., Mississauga, ON (Canada)

    1996-12-31

    As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs.

  15. Fuel bundle to pressure tube fretting in Bruce and Darlington

    International Nuclear Information System (INIS)

    Norsworthy, A.G.; Ditschun, A.

    1995-01-01

    As the fuel channel elongates due to creep, the fuel string moves relative to the inlet until the fuel pads at the inboard end eventually separate from the spacer sleeve, and the fuel resides on the burnish mark of the pressure tube. The bundle is then supported in a fashion which contributes to increased levels of vibration. Those pads which (due to geometric variation) have contact loads with the pressure tube within a certain range, vibrate, and cause significant fretting on the burnish mark, and further along at the midplane of the bundle. Inspection of the pressure tubes in Bruce A, Bruce B, and Darlington has revealed fret damage up to 0.55 mm at the burnish mark and slightly lower than this at the inlet bundle midplane. To date, all fret marks have been dealt with successfully without the need for tube replacement, but a program of work has been initiated to understand the mechanism and reduce the fretting. Such understanding is necessary to guide future design changes to the fuel bundle, to guide future inspection programs, to guide maintenance programs, and for longer term strategic planning. This paper discusses how the understanding of fretting has evolved and outlines a current hypothesis for the mechanism of fretting. The role of bundle geometry, excitation forces, and reactor conditions are reviewed, along with options under consideration to mitigate damage. (author). 4 refs., 2 tabs., 13 figs

  16. Standard test method for damage to contacting solid surfaces under fretting conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability. 1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a loading mass. The test method is intended for use in room temperature air, but future editions could include fretting in the presence of lubricants or other environments. 1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the damage to both surfaces in units of volume loss for the test method. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5...

  17. Laterally Driven Resonant Pressure Sensor with Etched Silicon Dual Diaphragms and Combined Beams

    Directory of Open Access Journals (Sweden)

    Xiaohui Du

    2016-01-01

    Full Text Available A novel structure of the resonant pressure sensor is presented in this paper, which tactfully employs intercoupling between dual pressure-sensing diaphragms and a laterally driven resonant strain gauge. After the resonant pressure sensor principle is introduced, the coupling mechanism of the diaphragms and resonator is analyzed and the frequency equation of the resonator based on the triangle geometry theory is developed for this new coupling structure. The finite element (FE simulation results match the theoretical analysis over the full scale of the device. This pressure sensor was first fabricated by dry/wet etching and thermal silicon bonding, followed by vacuum-packaging using anodic bonding technology. The test maximum error of the fabricated sensor is 0.0310%F.S. (full scale in the range of 30 to 190 kPa, its pressure sensitivity is negative and exceeding 8 Hz/kPa, and its Q-factor reaches 20,000 after wafer vacuum-packaging. A novel resonant pressure sensor with high accuracy is presented in this paper.

  18. A dual-unit pressure sensor for on-chip self-compensation of zero-point temperature drift

    International Nuclear Information System (INIS)

    Wang, Jiachou; Li, Xinxin

    2014-01-01

    A novel dual-unit piezoresistive pressure sensor, consisting of a sensing unit and a dummy unit, is proposed and developed for on-chip self-compensation for zero-point temperature drift. With an MIS (microholes inter-etch and sealing) process implemented only from the front side of single (1 1 1) silicon wafers, a pressure sensitive unit and another identically structured pressure insensitive dummy unit are compactly integrated on-chip to eliminate unbalance factors induced zero-point temperature-drift by mutual compensation between the two units. Besides, both units are physically suspended from silicon substrate to further suppress packaging-stress induced temperature drift. A simultaneously processes ventilation hole-channel structure is connected with the pressure reference cavity of the dummy unit to make it insensitive to detected pressure. In spite of the additional dummy unit, the sensor chip dimensions are still as small as 1.2 mm × 1.2 mm × 0.4 mm. The proposed dual-unit sensor is fabricated and tested, with the tested sensitivity being 0.104 mV kPa −1 3.3 V −1 , nonlinearity of less than 0.08% · FSO and overall accuracy error of ± 0.18% · FSO. Without using any extra compensation method, the sensor features an ultra-low temperature coefficient of offset (TCO) of 0.002% °C −1 · FSO that is much better than the performance of conventional pressure sensors. The highly stable and small-sized sensors are promising for low cost production and applications. (paper)

  19. Dual functional rhodium oxide nanocorals enabled sensor for both non-enzymatic glucose and solid-state pH sensing.

    Science.gov (United States)

    Dong, Qiuchen; Huang, Yikun; Song, Donghui; Wu, Huixiang; Cao, Fei; Lei, Yu

    2018-07-30

    Both pH-sensitive and glucose-responsive rhodium oxide nanocorals (Rh 2 O 3 NCs) were synthesized through electrospinning followed by high-temperature calcination. The as-prepared Rh 2 O 3 NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy, and then employed as a dual functional nanomaterial to fabricate a dual sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. The sensing performance of the Rh 2 O 3 NCs based dual sensor toward pH and glucose was evaluated using open circuit potential, cyclic voltammetry and amperometric techniques, respectively. The results show that the as-prepared Rh 2 O 3 NCs not only maintain accurate and reversible pH sensitivity of Rh 2 O 3 , but also demonstrate a good electrocatalytic activity toward glucose oxidation in alkaline medium with a sensitivity of 11.46 μA mM -1 cm -2 , a limit of detection of 3.1 μM (S/N = 3), and a reasonable selectivity against various interferents in non-enzymatic glucose detection. Its accuracy in determining glucose in human serum samples was further demonstrated. These features indicate that the as-prepared Rh 2 O 3 NCs hold great promise as a dual-functional sensing material in the development of a high-performance sensor forManjakkal both solid-state pH and non-enzymatic glucose sensing. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Wave propagation in coated cylinders with reference to fretting fatigue

    Indian Academy of Sciences (India)

    is to study stress wave propagation in cylinders with reference to high frequency fretting. ... The motivation for studying of fretting fatigue at higher frequency is to investigate the ... Hence focus in this work is given to thin rods and cylinders. The.

  1. Evaluation of surface characteristics under fretting of electrical contacts: Removal behaviour of hot dipped tin coating

    International Nuclear Information System (INIS)

    Park, Young Woo; Ramesh Bapu, G.N.K.; Lee, Kang Yong

    2009-01-01

    The fretting corrosion behaviour of hot dipped tin coating is investigated at low fretting cycles at ±25 μm displacement amplitude, 0.5N normal load, 3 Hz frequency, 45-50% relative humidity, and 25 ± 1 deg. C temperature. The typical characteristics of the change in contact resistance with fretting cycles are explained. The fretted surface is examined using laser scanning microscope, scanning electron microscope and energy dispersive X-ray analysis to assess the surface profile, extent of fretting damage, extent of oxidation and elemental distribution across the contact zone. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behaviour of tin coating. The variation of contact resistance clearly revealed the fretting of tin coating from 50 to 1200 cycles and the fretting of the substrate above 1200 cycles. The observed low and stable contact resistance region and the fluctuating resistance region at various fretting cycles are explained and substantiated with Scanning electron microscopy (SEM), laser scanning microscope (LSM) and energy dispersive analysis of X-rays (EDAX) analysis results of the fretted surface.

  2. FRET-based biosensors for the detection and quantification of AI-2 class of quorum sensing compounds.

    Science.gov (United States)

    Rajamani, Sathish; Sayre, Richard

    2011-01-01

    Intercellular small molecular weight signaling molecules modulate a variety of biological functions in bacteria. One of the more complex behaviors mediated by intercellular signaling molecules is the suite of activities regulated by quorum sensing molecules. These molecules mediate a variety of population-dependent responses, including the expression of genes that regulate bioluminescence, type III secretion, siderophore production, colony morphology, biofilm formation, and metalloprotease production. Given their central role in regulating these responses, the detection and quantification of QS molecules has important practical implications. Until recently, the detection of QS molecules from Gram-negative bacteria has relied primarily on bacterial reporter systems. These bioassays though immensely useful are subject to interference by compounds that affect bacterial growth and metabolism. In addition, the reporter response is highly dependent on culture age and cell population density. To overcome such limitations, we developed an in vitro protein-based assay system for the rapid detection and quantification of the furanosyl borate diester (BAI-2) subclass of autoinducer-2 (AI-2) QS molecules. The biosensor is based on the interaction of BAI-2 with the Vibrio harveyi QS receptor LuxP. Conformation changes associated with BAI-2 binding to the LuxP receptor change the orientation of cyan and yellow variants of GFP (CFP and YFP) fused the N- and C-termini, respectively, of the LuxP receptor. LuxP-BAI2 binding induces changes in fluorescence resonance energy transfer (FRET) between CFP and YFP, whose magnitude of change is ligand concentration dependent. A set of ligand-insensitive LuxP-mutant FRET protein sensor was also developed for use as control biosensors. The FRET-based BAI-2 biosensor responds selectively to both synthetic and biologically derived BAI-2compounds. This report describes the use of the LuxP-FRET biosensor for the detection and quantification of

  3. Development of Test Methods for Structural Components of a Dual Cooled Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu; Yoon, Kyung Ho; Kim, Jae Yong

    2009-01-15

    The most unique feature of a dual-cooled fuel is that the outer diameter of a fuel rod is considerably increased due to an internal coolant passage additionally formed inside the rod. This increases the fuel rod's weight and decreases the gap between the fuel rods. Change of the weight and gap causes the shape and the performance of a fuel rod support structure to be necessarily altered. It also alters the flow-induced vibration (FIV) as well as the fretting wear characteristics of a fuel rod. These are directly related with the integrity of the rod so that they should be investigated in the design stage. Finite element analysis and semi-empirical formulae can be used to roughly investigate the support performance and FIV of a fuel rod, respectively. However, the fretting wear characteristic can be investigated only through an experiment. The support performance and FIV need experiment as well to obtain the characteristics more accurately. Therefore, experimental investigation of those has been included in the present project scope. In the second year, it has been planned to establish the experimental devices and technologies to accommodate the altered dimensions and feature of a dual-cooled fuel. As a result, devices to obtain the characteristics of fuel rod supports and holddown springs were developed. As for the FIV and fretting wear characteristics, the existing facilities were modified. Experimental procedures were also re-established this year.

  4. APPL proteins FRET at the BAR: direct observation of APPL1 and APPL2 BAR domain-mediated interactions on cell membranes using FRET microscopy.

    Directory of Open Access Journals (Sweden)

    Heidi J Chial

    2010-08-01

    Full Text Available Human APPL1 and APPL2 are homologous RAB5 effectors whose binding partners include a diverse set of transmembrane receptors, signaling proteins, and phosphoinositides. APPL proteins associate dynamically with endosomal membranes and are proposed to function in endosome-mediated signaling pathways linking the cell surface to the cell nucleus. APPL proteins contain an N-terminal Bin/Amphiphysin/Rvs (BAR domain, a central pleckstrin homology (PH domain, and a C-terminal phosphotyrosine binding (PTB domain. Previous structural and biochemical studies have shown that the APPL BAR domains mediate homotypic and heterotypic APPL-APPL interactions and that the APPL1 BAR domain forms crescent-shaped dimers. Although previous studies have shown that APPL minimal BAR domains associate with curved cell membranes, direct interaction between APPL BAR domains on cell membranes in vivo has not been reported.Herein, we used a laser-scanning confocal microscope equipped with a spectral detector to carry out fluorescence resonance energy transfer (FRET experiments with cyan fluorescent protein/yellow fluorescent protein (CFP/YFP FRET donor/acceptor pairs to examine interactions between APPL minimal BAR domains at the subcellular level. This comprehensive approach enabled us to evaluate FRET levels in a single cell using three methods: sensitized emission, standard acceptor photobleaching, and sequential acceptor photobleaching. We also analyzed emission spectra to address an outstanding controversy regarding the use of CFP donor/YFP acceptor pairs in FRET acceptor photobleaching experiments, based on reports that photobleaching of YFP converts it into a CFP-like species.All three methods consistently showed significant FRET between APPL minimal BAR domain FRET pairs, indicating that they interact directly in a homotypic (i.e., APPL1-APPL1 and APPL2-APPL2 and heterotypic (i.e., APPL1-APPL2 manner on curved cell membranes. Furthermore, the results of our experiments

  5. A dual pH and temperature responsive polymeric fluorescent sensor and its imaging application in living cells.

    Science.gov (United States)

    Yin, Liyan; He, Chunsheng; Huang, Chusen; Zhu, Weiping; Wang, Xin; Xu, Yufang; Qian, Xuhong

    2012-05-11

    A polymeric fluorescent sensor PNME, consisting of A4 and N-isopropylacrylamide (NIPAM) units, was synthesized. PNME exhibited dual responses to pH and temperature, and could be used as an intracellular pH sensor for lysosomes imaging. Moreover, it also could sense different temperature change in living cells at 25 and 37 °C, respectively. This journal is © The Royal Society of Chemistry 2012

  6. Turbulence induced Fretting-wear characteristics of steam generator helical tubes

    International Nuclear Information System (INIS)

    Jhung, Myung Jo; Jo, Jong Chull; Kim, Hho Jung; Yune, Young Gill; Yu, Seon Oh

    2005-01-01

    This study addresses safety assessment of the potential for fretting-wear damages on steam generator helical tubes due to turbulence-induced vibration in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for helical type tubes with various conditions. Special emphases are put on the effects of coil diameter and the number of turns on the modal and fretting wear characteristics of tubes. Also, investigated are the effects of external pressure on the tube modal characteristics as well as the effects of turbulence induced vibration on the fretting-wear characteristics of tubes

  7. Fretting fatigue behaviour of Ni-free high-nitrogen stainless steel in a simulated body fluid

    Directory of Open Access Journals (Sweden)

    Norio Maruyama, Sachiko Hiromoto, Eiji Akiyama and Morihiko Nakamura

    2013-01-01

    Full Text Available Fretting fatigue behaviour of Ni-free high-nitrogen steel (HNS with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-. For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR both in air and in PBS(-. A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR. The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area.

  8. N-way FRET microscopy of multiple protein-protein interactions in live cells.

    Directory of Open Access Journals (Sweden)

    Adam D Hoppe

    Full Text Available Fluorescence Resonance Energy Transfer (FRET microscopy has emerged as a powerful tool to visualize nanoscale protein-protein interactions while capturing their microscale organization and millisecond dynamics. Recently, FRET microscopy was extended to imaging of multiple donor-acceptor pairs, thereby enabling visualization of multiple biochemical events within a single living cell. These methods require numerous equations that must be defined on a case-by-case basis. Here, we present a universal multispectral microscopy method (N-Way FRET to enable quantitative imaging for any number of interacting and non-interacting FRET pairs. This approach redefines linear unmixing to incorporate the excitation and emission couplings created by FRET, which cannot be accounted for in conventional linear unmixing. Experiments on a three-fluorophore system using blue, yellow and red fluorescent proteins validate the method in living cells. In addition, we propose a simple linear algebra scheme for error propagation from input data to estimate the uncertainty in the computed FRET images. We demonstrate the strength of this approach by monitoring the oligomerization of three FP-tagged HIV Gag proteins whose tight association in the viral capsid is readily observed. Replacement of one FP-Gag molecule with a lipid raft-targeted FP allowed direct observation of Gag oligomerization with no association between FP-Gag and raft-targeted FP. The N-Way FRET method provides a new toolbox for capturing multiple molecular processes with high spatial and temporal resolution in living cells.

  9. Methodological considerations for global analysis of cellular FLIM/FRET measurements

    Science.gov (United States)

    Adbul Rahim, Nur Aida; Pelet, Serge; Kamm, Roger D.; So, Peter T. C.

    2012-02-01

    Global algorithms can improve the analysis of fluorescence energy transfer (FRET) measurement based on fluorescence lifetime microscopy. However, global analysis of FRET data is also susceptible to experimental artifacts. This work examines several common artifacts and suggests remedial experimental protocols. Specifically, we examined the accuracy of different methods for instrument response extraction and propose an adaptive method based on the mean lifetime of fluorescent proteins. We further examined the effects of image segmentation and a priori constraints on the accuracy of lifetime extraction. Methods to test the applicability of global analysis on cellular data are proposed and demonstrated. The accuracy of global fitting degrades with lower photon count. By systematically tracking the effect of the minimum photon count on lifetime and FRET prefactors when carrying out global analysis, we demonstrate a correction procedure to recover the correct FRET parameters, allowing us to obtain protein interaction information even in dim cellular regions with photon counts as low as 100 per decay curve.

  10. Roughness Influence on Initiation of Fretting Fatigue Scar of Ti-6Al-4V Alloy

    Science.gov (United States)

    Capitanu, L.; Badita, L. L.; Florescu, V.; Tiganesteanu, C.

    2018-01-01

    This paper reports on the experimental studies undertaken to detect the early stage when appears the fretting wear of the Ti-6Al-4V alloy used for the hip prostheses. Wear is a critical aspect for estimating the fretting fatigue. Studies were performed on samples of special shape, in order to be able to study the influence of in contact surfaces roughness on the durability to fretting. Fretting buffers, with roughnesses Ra of the contact surface of 0.015 and 0.045 μm, and Ti-6Al-4V samples with roughnesses Ra = 0.045 μm, Ra = 0.075 μm and Ra = 0.19 μm, were used. Testing periods of 3 seconds, 1 minute and 5 minutes were selected to capture the moment of the fretting scar appearance, long before these initiate the eventual fretting cracking. Simultaneously with fretting wear of the surface, the friction coefficient was also measured. From the in time evolution determinations of the fretting wear, it resulted that, under the experimental conditions used, the minimum wear occurs at a certain value of the roughness and not at the minimum roughness. Surprisingly, the minimum friction coefficient does not coincide with the minimum fretting wear.

  11. Recognition of dual targets by a molecular beacon-based sensor: subtyping of influenza A virus.

    Science.gov (United States)

    Lee, Chun-Ching; Liao, Yu-Chieh; Lai, Yu-Hsuan; Lee, Chang-Chun David; Chuang, Min-Chieh

    2015-01-01

    A molecular beacon (MB)-based sensor to offer a decisive answer in combination with information originated from dual-target inputs is designed. The system harnesses an assistant strand and thermodynamically favored designation of unpaired nucleotides (UNs) to process the binary targets in "AND-gate" format and report fluorescence in "off-on" mechanism via a formation of a DNA four-way junction (4WJ). By manipulating composition of the UNs, the dynamic fluorescence difference between the binary targets-coexisting circumstance and any other scenario was maximized. Characteristic equilibrium constant (K), change of entropy (ΔS), and association rate constant (k) between the association ("on") and dissociation ("off") states of the 4WJ were evaluated to understand unfolding behavior of MB in connection to its sensing capability. Favorable MB and UNs were furthermore designed toward analysis of genuine genetic sequences of hemagglutinin (HA) and neuraminidase (NA) in an influenza A H5N2 isolate. The MB-based sensor was demonstrated to yield a linear calibration range from 1.2 to 240 nM and detection limit of 120 pM. Furthermore, high-fidelity subtyping of influenza virus was implemented in a sample of unpurified amplicons. The strategy opens an alternative avenue of MB-based sensors for dual targets toward applications in clinical diagnosis.

  12. A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor.

    Science.gov (United States)

    Du, Lei; Sun, Qiao; Cai, Changqing; Bai, Jie; Fan, Zhe; Zhang, Yue

    2018-04-05

    Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument.

  13. Mining the Sinorhizobium meliloti transportome to develop FRET biosensors for sugars, dicarboxylates and cyclic polyols.

    Directory of Open Access Journals (Sweden)

    Alexandre Bourdès

    Full Text Available Förster resonance energy transfer (FRET biosensors are powerful tools to detect biologically important ligands in real time. Currently FRET bisosensors are available for twenty-two compounds distributed in eight classes of chemicals (two pentoses, two hexoses, two disaccharides, four amino acids, one nucleobase, two nucleotides, six ions and three phytoestrogens. To expand the number of available FRET biosensors we used the induction profile of the Sinorhizobium meliloti transportome to systematically screen for new FRET biosensors.Two new vectors were developed for cloning genes for solute-binding proteins (SBPs between those encoding FRET partner fluorescent proteins. In addition to a vector with the widely used cyan and yellow fluorescent protein FRET partners, we developed a vector using orange (mOrange2 and red fluorescent protein (mKate2 FRET partners. From the sixty-nine SBPs tested, seven gave a detectable FRET signal change on binding substrate, resulting in biosensors for D-quinic acid, myo-inositol, L-rhamnose, L-fucose, β-diglucosides (cellobiose and gentiobiose, D-galactose and C4-dicarboxylates (malate, succinate, oxaloacetate and fumarate. To our knowledge, we describe the first two FRET biosensor constructs based on SBPs from Tripartite ATP-independent periplasmic (TRAP transport systems.FRET based on orange (mOrange2 and red fluorescent protein (mKate2 partners allows the use of longer wavelength light, enabling deeper penetration of samples at lower energy and increased resolution with reduced back-ground auto-fluorescence. The FRET biosensors described in this paper for four new classes of compounds; (i cyclic polyols, (ii L-deoxy sugars, (iii β-linked disaccharides and (iv C4-dicarboxylates could be developed to study metabolism in vivo.

  14. Characterizing single-molecule FRET dynamics with probability distribution analysis.

    Science.gov (United States)

    Santoso, Yusdi; Torella, Joseph P; Kapanidis, Achillefs N

    2010-07-12

    Probability distribution analysis (PDA) is a recently developed statistical tool for predicting the shapes of single-molecule fluorescence resonance energy transfer (smFRET) histograms, which allows the identification of single or multiple static molecular species within a single histogram. We used a generalized PDA method to predict the shapes of FRET histograms for molecules interconverting dynamically between multiple states. This method is tested on a series of model systems, including both static DNA fragments and dynamic DNA hairpins. By fitting the shape of this expected distribution to experimental data, the timescale of hairpin conformational fluctuations can be recovered, in good agreement with earlier published results obtained using different techniques. This method is also applied to studying the conformational fluctuations in the unliganded Klenow fragment (KF) of Escherichia coli DNA polymerase I, which allows both confirmation of the consistency of a simple, two-state kinetic model with the observed smFRET distribution of unliganded KF and extraction of a millisecond fluctuation timescale, in good agreement with rates reported elsewhere. We expect this method to be useful in extracting rates from processes exhibiting dynamic FRET, and in hypothesis-testing models of conformational dynamics against experimental data.

  15. Highly sensitive digital optical sensor with large measurement range based on the dual-microring resonator with waveguide-coupled feedback

    International Nuclear Information System (INIS)

    Xiang Xing-Ye; Wang Kui-Ru; Yuan Jin-Hui; Jin Bo-Yuan; Sang Xin-Zhu; Yu Chong-Xiu

    2014-01-01

    We propose a novel high-performance digital optical sensor based on the Mach—Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of a conventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case

  16. Förster Resonance Energy Transfer (FRET) from Triton X-100 to 4-benzothiazol-2-yl-phenol: Varying FRET efficiency with CMC of the donor (Triton X-100)

    International Nuclear Information System (INIS)

    Paul, Bijan Kumar; Ganguly, Aniruddha; Karmakar, Saswati; Guchhait, Nikhil

    2013-01-01

    A heterocyclic compound viz., 4-benzothiazol-2-yl-phenol (4B2YP) has been synthesized and its photophysics have been examined through steady-state absorption, emission and time resolved emission spectroscopic techniques, in brief. Then 4B2YP has been exploited as an acceptor in the Förster Resonance Energy Transfer (FRET) process from photoexcited benzene aromatic nucleus of Triton X-100 (TX-100) surfactant. Dependence of the energy transfer efficiency on the donor concentration with respect to its critical micelle concentration (CMC) is clearly reflected in the study. High values of Stern–Volmer constant (K SV ) for quenching of the donor fluorescence in the presence of the acceptor suggest the operation of long-range dipole–dipole interaction in the course of energy transfer process, while the inference is aptly supported from time resolved fluorescence decay results. Experimental results show maximum FRET efficiency at the CMC of the donor (TX-100). -- Highlights: • FRET from neutral surfactant Triton X-100 to chromophore 4-benzothiazol-2-yl-phenol. • Steady state and time resolved spectroscopy. • Long-range dipole–dipole interaction responsible for FRET. • FRET efficiency as a measure of CMC of surfactant

  17. Förster Resonance Energy Transfer (FRET) from Triton X-100 to 4-benzothiazol-2-yl-phenol: Varying FRET efficiency with CMC of the donor (Triton X-100)

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Bijan Kumar, E-mail: bijan.paul.chem.cu@gmail.com [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India); Ganguly, Aniruddha [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India); Karmakar, Saswati [Department of Chemistry, Sree Chaitanya College, Habra, North 24 Parganas (India); Guchhait, Nikhil, E-mail: nguchhait@yahoo.com [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India)

    2013-11-15

    A heterocyclic compound viz., 4-benzothiazol-2-yl-phenol (4B2YP) has been synthesized and its photophysics have been examined through steady-state absorption, emission and time resolved emission spectroscopic techniques, in brief. Then 4B2YP has been exploited as an acceptor in the Förster Resonance Energy Transfer (FRET) process from photoexcited benzene aromatic nucleus of Triton X-100 (TX-100) surfactant. Dependence of the energy transfer efficiency on the donor concentration with respect to its critical micelle concentration (CMC) is clearly reflected in the study. High values of Stern–Volmer constant (K{sub SV}) for quenching of the donor fluorescence in the presence of the acceptor suggest the operation of long-range dipole–dipole interaction in the course of energy transfer process, while the inference is aptly supported from time resolved fluorescence decay results. Experimental results show maximum FRET efficiency at the CMC of the donor (TX-100). -- Highlights: • FRET from neutral surfactant Triton X-100 to chromophore 4-benzothiazol-2-yl-phenol. • Steady state and time resolved spectroscopy. • Long-range dipole–dipole interaction responsible for FRET. • FRET efficiency as a measure of CMC of surfactant.

  18. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    Science.gov (United States)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  19. Effects of fretting fatigue on the residual stress of shot peened Ti-6Al-4V samples

    International Nuclear Information System (INIS)

    Martinez, S.A.; Sathish, S.; Blodgett, M.P.; Mall, S.; Namjoshi, S.

    2005-01-01

    X-ray diffraction residual stress measurement has been utilized as nondestructive tool for the characterization of fretting fatigue damage in shot peened samples of Ti-6Al-4V. Prior to fretting fatigue damage, compressive residual stresses were found to be uniform over the entire face of the sample and independent of the measurement direction. After fretting fatigue, inside and in the vicinity of the fretting damage zone large relaxation of compressive residual stress was observed. An anisotropic residual stress distribution has been observed in the fretting fatigue damaged region. Residual stress measurements in interrupted fretting fatigue experiments showed that the relaxation of residual stress increases as the number of fretting fatigue cycles increase. The results are discussed in the light of their importance in establishing X-ray diffraction residual stress measurement technique as a nondestructive tool to characterize fretting fatigue damage

  20. Fuel-element vibration and bearing pad to pressure tube fretting

    International Nuclear Information System (INIS)

    Fisher, N.J.; Taylor, C.E.; Pettigrew, M.J.

    1990-08-01

    Fuel channel operation under boiling condition results in increased flow velocities, which may lead to unacceptable fuel-element vibration and bearing pad to pressure tube fretting. The existing endurance test database does not fully cover the range of future channel operating conditions. In particular, after refuelling, some channels for future designs may operate with two-phase flow conditions outside the range of endurance test conditions. Full-scale endurance testing at realistic steam-water conditions involves substantial energy costs. Therefore, fundamental laboratory investigations were conducted to define and endurance test matrix which adequately envelops the future range of operating conditions while minimizing both the number of tests and the energy requirement of individual tests. The main focus of the laboratory investigations was to establish the relationships between: fuel channel flow conditions and fuel-element vibration; and fuel-element vibration and bearing pad to pressure tube fretting. The vibration response of a single fuel element was measured over a wide range of operating conditions covering realistic fuel channel conditions and simulated endurance testing conditions. For higher void fractions, the vibration amplitudes measured in air/water were much higher than in steam/water, while for low void fractions, the amplitudes were similar. The measured amplitudes in steam/water varied very little over the range of temperature and pressure investigated. The effects of temperature, pressure tube oxide thickness, vibration amplitude and bearing pad manufacturer on pressure tube fretting were investigated. The fretting rate is extremely temperature dependent. For vibration amplitudes about three or four times greater than expected in-reactor conditions, peak fretting rates were observed in the 225 to 286 degrees C temperature range. Fretting rates were seven times less at the higher temperatures of 300 and 315 degrees C, and the lower temperatures

  1. A hybrid Fabry–Perot/Michelson interferometer sensor using a dual asymmetric core microstructured fiber

    International Nuclear Information System (INIS)

    Frazão, O; Silva, S F; Viegas, J; Baptista, J M; Santos, J L; Roy, P

    2010-01-01

    A hybrid Fabry–Perot/Michelson interferometer sensor using a dual asymmetric core microstructured fiber is demonstrated. The hybrid interferometer presents three waves. Two parallel Fabry–Perot cavities with low finesse are formed between the splice region and the end of a dual-core microstructured fiber. A Michelson configuration is obtained by the two small cores of the microstructured fiber. The spectral response of the hybrid interferometer presents two pattern fringes with different frequencies due to the respective optical path interferometers. The hybrid interferometer was characterized in strain and temperature presenting different sensitivity coefficients for each topology. Due to these characteristics, this novel sensing head is able to measure strain and temperature, simultaneously

  2. Application of FRET probes in the analysis of neuronal plasticity

    Directory of Open Access Journals (Sweden)

    Yoshibumi eUeda

    2013-10-01

    Full Text Available Breakthroughs in imaging techniques and optical probes in recent years have revolutionized the field of life sciences in ways that traditional methods could never match. The spatial and temporal regulation of molecular events can now be studied with great precision. There have been several key discoveries that have made this possible. Since GFP was cloned in 1992, it has become the dominant tracer of proteins in living cells. Then the evolution of color variants of GFP opened the door to the application of Förster resonance energy transfer (FRET, which is now widely recognized as a powerful tool to study complicated signal transduction events and interactions between molecules. Employment of fluorescent lifetime imaging microscopy (FLIM allows the precise detection of FRET in small subcellular structures such as dendritic spines. In this review, we provide an overview of the basic and practical aspects of FRET imaging and discuss how different FRET probes have revealed insights into the molecular mechanisms of synaptic plasticity and enabled visualization of neuronal network activity both in vitro and in vivo.

  3. Influence of plasma molybdenizing and shot-peening on fretting damage behavior of titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chang-bin, E-mail: tcbtop@126.com [School of Metallurgy and Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi 710055 (China); Institute of Corrosion and Protection, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China); Liu, Dao-xin, E-mail: liudaox@nwpu.edu.cn [Institute of Corrosion and Protection, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China); Tang, Bin [Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan Shanxi 030024 (China); Zhang, Xiao-hua [Institute of Corrosion and Protection, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China); Qin, Lin [Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan Shanxi 030024 (China); Liu, Cheng-song [Institute of Corrosion and Protection, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China)

    2016-12-30

    Highlights: • Plasma molybdenizing increases FW resistance of Ti6Al4V, but reduces its FF life. • Shot-peened plasmamolybdenizing surface enhances FW and FF resistance of Ti6Al4V. • Combined treatment yields low surface-roughness & high hardness gradient distribution. • Combined treatment yields beneficial residual compressive stress & good toughness. • Anti-wear & -fatigue performance improvements for surface engineering applications. - Abstract: Effect of plasma molybdenizing and shot-peening on fretting wear and fretting fatigue behaviors of Ti6Al4V alloy was investigated. The plasma molybdenized layer composed of a dense molybdenum deposition layer and a Mo–Ti solid–solution layer can increase surface hardness by 2.8 times and cause its volume loss by fretting wear to decrease to 1/14 compared with that of the substrate. Plasma molybdenized treatment results in a significant decrease in resistance of the substrate to fretting fatigue. It is ascribed that the molybdenized layer with high hardness yields a low toughness, and its high surface roughness leads to a micro-notched effect. However, proper combination plasma molybdenizing and subsequent shot-peening may enhance the simultaneous fretting fatigue and fretting wear resistance of Ti6Al4V significantly, which can decrease the fretting wear volume loss to 1/27, and may increase the fretting fatigue life by more than 69 times. A synergistic improvement in fretting fatigue of the titanium alloy by combining surface alloying with shot-peening can be achieved. The results indicate that a beneficial residual compressive stress distribution, high surface hardness with suitable hardness gradient distribution, good apparent toughness, relatively low surface roughness, and excellent surface integrity are achieved.

  4. Fretting and wear of stainless and ferritic steels in LMFBR steam generators

    International Nuclear Information System (INIS)

    Lewis, M.W.J.; Campbell, C.S.

    1981-01-01

    Steam generators for LMFBR's may be subject to both fretting wear as a result of flow-induced vibrations and to wear from larger amplitude sliding movements from thermal changes. Results of tests simulating the latter are given for stainless and ferritic steels. For the assessment of fretting wear damage, vibration assessments must be combined with data on specific wear rates. Test mechanisms used to study fretting in sodium covering impact, impact-slide and pure rubbing are described and results presented. (author)

  5. MIL-L-87177 and CLT:X-10 Lubricants Improve Electrical Connector Fretting Corrosion Behavior

    International Nuclear Information System (INIS)

    AUKLAND, NEIL R.; HANLON, JAMES T.

    1999-01-01

    We have conducted a fretting research project using MIL-L-87177 and CLT: X-10 lubricants on Nano-miniature connectors. When they were fretted without lubricant, individual connectors first exceeded our 0.5 ohm failure criteria from 2,341 to 45,238 fretting cycles. With additional fretting, their contact resistance increased to more than 100,000 ohms. Unmodified MIL-L-87177 lubricant delayed the onset of first failure to between 430,000 and over 20,000,000 fretting cycles. MIL-L-87177 modified by addition of Teflon powder delayed first failure to beyond 5 million fretting cycles. Best results were obtained when Teflon was used and also when both the straight and modified lubricants were poured into and then out of the connector. CLT: X-10 lubricant delayed the onset of first failure to beyond 55 million cycles in one test where a failure was actually observed and to beyond 20 million cycles in another that was terminated without failure. CLT: X-10 recovered an unlubricated connector driven deeply into failure, with six failed pins recovering immediately and four more recovering during an additional 420 thousand fretting cycles. MIL-L-87177 was not able to recover a connector under similar conditions

  6. Inferring properties of disordered chains from FRET transfer efficiencies

    Science.gov (United States)

    Zheng, Wenwei; Zerze, Gül H.; Borgia, Alessandro; Mittal, Jeetain; Schuler, Benjamin; Best, Robert B.

    2018-03-01

    Förster resonance energy transfer (FRET) is a powerful tool for elucidating both structural and dynamic properties of unfolded or disordered biomolecules, especially in single-molecule experiments. However, the key observables, namely, the mean transfer efficiency and fluorescence lifetimes of the donor and acceptor chromophores, are averaged over a broad distribution of donor-acceptor distances. The inferred average properties of the ensemble therefore depend on the form of the model distribution chosen to describe the distance, as has been widely recognized. In addition, while the distribution for one type of polymer model may be appropriate for a chain under a given set of physico-chemical conditions, it may not be suitable for the same chain in a different environment so that even an apparently consistent application of the same model over all conditions may distort the apparent changes in chain dimensions with variation of temperature or solution composition. Here, we present an alternative and straightforward approach to determining ensemble properties from FRET data, in which the polymer scaling exponent is allowed to vary with solution conditions. In its simplest form, it requires either the mean FRET efficiency or fluorescence lifetime information. In order to test the accuracy of the method, we have utilized both synthetic FRET data from implicit and explicit solvent simulations for 30 different protein sequences, and experimental single-molecule FRET data for an intrinsically disordered and a denatured protein. In all cases, we find that the inferred radii of gyration are within 10% of the true values, thus providing higher accuracy than simpler polymer models. In addition, the scaling exponents obtained by our procedure are in good agreement with those determined directly from the molecular ensemble. Our approach can in principle be generalized to treating other ensemble-averaged functions of intramolecular distances from experimental data.

  7. Impact Fretting Wear Behavior of Alloy 690 Tubes in Dry and Deionized Water Conditions

    Institute of Scientific and Technical Information of China (English)

    Zhen-Bing Cai; Jin-Fang Peng; Hao Qian; Li-Chen Tang; Min-Hao Zhu

    2017-01-01

    The impact fretting wear has largely occurred at nuclear power device induced by the flow-induced vibration,and it will take potential hazards to the service of the equipment.However,the present study focuses on the tangential fretting wear of alloy 690 tubes.Research on impact fretting wear of alloy 690 tubes is limited and the related research is imminent.Therefore,impact fretting wear behavior of alloy 690 tubes against 304 stainless steels is investigated.Deionized water is used to simulate the flow environment of the equipment,and the dry environment is used for comparison.Varied analytical techniques are employed to characterize the wear and tribochemical behavior during impact fretting wear.Characterization results indicate that cracks occur at high impact load in both water and dry equipment;however,the water as a medium can significantly delay the cracking time.The crack propagation behavior shows a jagged shape in the water,but crack extended disorderly in dry equipment because the water changed the stress distribution and retarded the friction heat during the wear process.The SEM and XPS analysis shows that the main failure mechanisms of the tube under impact fretting are fatigue wear and friction oxidation.The effect of medium(water) on fretting wear is revealed,which plays a potential and promising role in the service of nuclear power device and other flow equipments.

  8. Dual-Recognition Förster Resonance Energy Transfer Based Platform for One-Step Sensitive Detection of Pathogenic Bacteria Using Fluorescent Vancomycin-Gold Nanoclusters and Aptamer-Gold Nanoparticles.

    Science.gov (United States)

    Yu, Mengqun; Wang, Hong; Fu, Fei; Li, Linyao; Li, Jing; Li, Gan; Song, Yang; Swihart, Mark T; Song, Erqun

    2017-04-04

    The effective monitoring, identification, and quantification of pathogenic bacteria is essential for addressing serious public health issues. In this study, we present a universal and facile one-step strategy for sensitive and selective detection of pathogenic bacteria using a dual-molecular affinity-based Förster (fluorescence) resonance energy transfer (FRET) platform based on the recognition of bacterial cell walls by antibiotic and aptamer molecules, respectively. As a proof of concept, Vancomycin (Van) and a nucleic acid aptamer were employed in a model dual-recognition scheme for detecting Staphylococcus aureus (Staph. aureus). Within 30 min, by using Van-functionalized gold nanoclusters and aptamer-modified gold nanoparticles as the energy donor and acceptor, respectively, the FRET signal shows a linear variation with the concentration of Staph. aureus in the range from 20 to 10 8 cfu/mL with a detection limit of 10 cfu/mL. Other nontarget bacteria showed negative results, demonstrating the good specificity of the approach. When employed to assay Staph. aureus in real samples, the dual-recognition FRET strategy showed recoveries from 99.00% to the 109.75% with relative standard derivations (RSDs) less than 4%. This establishes a universal detection platform for sensitive, specific, and simple pathogenic bacteria detection, which could have great impact in the fields of food/public safety monitoring and infectious disease diagnosis.

  9. Numerical study of on-fiber metal film geometry on behavior of dual parameter SFBG sensors

    International Nuclear Information System (INIS)

    Goodarzy, Behnam; Foroozmehr, Ehsan; Alemohammad, Hamidreza

    2016-01-01

    In this paper, a numerical model for simulating a dual parameter super-structure FBG (SFBG) with on-fiber deposited thin films is developed. A periodic on-fiber thin coating of silver on FBG sensors provides the ability of measuring two parameters of strain and temperature simultaneously. The model consists of a mechanical model to determine the strain of the sensor caused by different loading conditions, coupled with an optical model to calculate the reflected spectrum of the SFBG sensor. A guideline is introduced for designing a SFBG by studying the effect of coating period, coating duty cycle, and coating thickness. The results show that the sideband spacing in such SFBGs is only affected by the coating period while the Bragg peak sensitivity does not depend on coating period. Also the coating duty cycle and the coating thickness can affect both sensitivity of the Bragg peak and the measuring range of a sensor. The validity of the results was studied by comparing with previously reported data. (paper)

  10. A Novel Dual Separate Paths (DSP) Algorithm Providing Fault-Tolerant Communication for Wireless Sensor Networks.

    Science.gov (United States)

    Tien, Nguyen Xuan; Kim, Semog; Rhee, Jong Myung; Park, Sang Yoon

    2017-07-25

    Fault tolerance has long been a major concern for sensor communications in fault-tolerant cyber physical systems (CPSs). Network failure problems often occur in wireless sensor networks (WSNs) due to various factors such as the insufficient power of sensor nodes, the dislocation of sensor nodes, the unstable state of wireless links, and unpredictable environmental interference. Fault tolerance is thus one of the key requirements for data communications in WSN applications. This paper proposes a novel path redundancy-based algorithm, called dual separate paths (DSP), that provides fault-tolerant communication with the improvement of the network traffic performance for WSN applications, such as fault-tolerant CPSs. The proposed DSP algorithm establishes two separate paths between a source and a destination in a network based on the network topology information. These paths are node-disjoint paths and have optimal path distances. Unicast frames are delivered from the source to the destination in the network through the dual paths, providing fault-tolerant communication and reducing redundant unicast traffic for the network. The DSP algorithm can be applied to wired and wireless networks, such as WSNs, to provide seamless fault-tolerant communication for mission-critical and life-critical applications such as fault-tolerant CPSs. The analyzed and simulated results show that the DSP-based approach not only provides fault-tolerant communication, but also improves network traffic performance. For the case study in this paper, when the DSP algorithm was applied to high-availability seamless redundancy (HSR) networks, the proposed DSP-based approach reduced the network traffic by 80% to 88% compared with the standard HSR protocol, thus improving network traffic performance.

  11. Influence of Fretting on Flexural Fatigue of 304 Stainless Steel and Mild Steel

    National Research Council Canada - National Science Library

    Bill, Robert

    1978-01-01

    Fretting fatigue experiments conducted on 304 stainless steel using a flexural-fatigue test arrangement with bolted-on fretting pads have demonstrated that fatigue life is reduced by at least a factor...

  12. Characteristics of CANDU fuel bundles that caused pressure tube fretting at the bundle midplane

    Energy Technology Data Exchange (ETDEWEB)

    Dennier, D; Manzer, A M [Atomic Energy of Canada Ltd., Mississauga, ON (Canada); Koehn, E [Ontario Hydro, Toronto, ON (Canada)

    1996-12-31

    Detailed measurements on new bundles, and those that caused fretting during in- and out-reactor tests, have given insight into the factors responsible for fretting at the midplane of the inlet bundle. Bottom fuel elements that were attached near radial endplate spokes and had inboard bearing pads in the rolled joint cavity produced a significant portion of the observed fret marks. These elements are influenced by several driving forces that deflect the centre bearing pads towards the pressure tube surface. The evidence suggests that slight changes in bundle design may be possible to reduce pressure tube fretting. (author). 4 refs., 3 tabs., 8 figs.

  13. Characterizing ligand-gated ion channel receptors with genetically encoded Ca2++ sensors.

    Directory of Open Access Journals (Sweden)

    John G Yamauchi

    2011-01-01

    Full Text Available We present a cell based system and experimental approach to characterize agonist and antagonist selectivity for ligand-gated ion channels (LGIC by developing sensor cells stably expressing a Ca(2+ permeable LGIC and a genetically encoded Förster (or fluorescence resonance energy transfer (FRET-based calcium sensor. In particular, we describe separate lines with human α7 and human α4β2 nicotinic acetylcholine receptors, mouse 5-HT(3A serotonin receptors and a chimera of human α7/mouse 5-HT(3A receptors. Complete concentration-response curves for agonists and Schild plots of antagonists were generated from these sensors and the results validate known pharmacology of the receptors tested. Concentration-response relations can be generated from either the initial rate or maximal amplitudes of FRET-signal. Although assaying at a medium throughput level, this pharmacological fluorescence detection technique employs a clonal line for stability and has versatility for screening laboratory generated congeners as agonists or antagonists on multiple subtypes of ligand-gated ion channels. The clonal sensor lines are also compatible with in vivo usage to measure indirectly receptor activation by endogenous neurotransmitters.

  14. Development of a Dual Solid-State pH-AT Sensor

    Science.gov (United States)

    Briggs, E.; Martz, T. R.; Kummel, A.; Sandoval, S.; Erten, A.

    2016-02-01

    Here we report on our progress toward development of a solid state, reagentless sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (AT) using ion sensitive field effect transistor (ISFET) technology. The goal of this work is to provide a means of continuous, direct measurement of the seawater carbon dioxide system through measurement of two "master variables" (pH and AT). ISFET-based pH sensors that achieve 0.001 precision are presently in widespread use on autonomous oceanographic platforms. Modifications to an ISFET allow a nL-scale acid-base titration of total alkalinity to be carried out in 10 s. Titrant, H+, is generated through the electrolysis of water on the surface of the chip eliminating the requirement of external reagents. Initial characterization has been performed titrating individual components (i.e. OH-, HCO3-, CO32-, PO43-) of seawater AT. Based on previous work by others in simple acid-base systems and our preliminary results in seawater we feel that it is within reach to set a benchmark goal of 10 μmol kg-1 precision in AT. The estimated resolution of this dual pH-AT sensor translates to approximately 0.5 and 0.7% error in Total Dissolved Inorganic Carbon (CT) and pCO2 respectively and would have a number of immediate applications for investigating biogeochemical processes where strong gradients exist over short distances and in rapidly changing environments.

  15. Research on dual-parameter optical fiber sensor based on thin-core fiber and spherical structure

    Science.gov (United States)

    Tong, Zhengrong; Wang, Xue; Zhang, Weihua; Xue, Lifang

    2018-04-01

    A novel dual-parameter optical fiber sensor is proposed and experimentally demonstrated. The proposed sensor is based on a fiber in-line Mach-Zehnder interferometer, which is fabricated by sandwiching a section of thin-core fiber between two spherical structures made of single-mode fibers. The transmission spectrum exhibits the response of the interference between the core and the different cladding modes. Due to the different wavelength shifts of the two selected dips, the simultaneous measurement of temperature and the surrounding refractive index can be achieved. The measured temperature sensitivities are 0.067 nm/°C and 0.050 nm/°C, and the refractive index sensitivities are  -119.9 nm/RIU and  -69.71 nm/RIU, respectively. In addition, the compact size, simple fabrication and cost-effectiveness of the fiber sensor are also advantages.

  16. Experimental facility design for study of fretting in steam generator tubes

    International Nuclear Information System (INIS)

    Balbiani, J.P.; Bergant, M.; Yawny, A.

    2012-01-01

    The design of an experimental facility for fretting wear testing of steam generator tubes under pressurized water up to 340 o C, is presented. The main component of the device consists in an autoclave which permits to recreate steam generator operating conditions. CAD CATIA V5R18, CAE ABAQUS and ASME Sec. VII Div. 1 (Rules for Construction of Pressure Vessels) were used along the design process. The design of the autoclave included the pressure vessel itself and the necessary flanges and nozzles. In addition, an axial dynamic sealing system was designed to allow for actuation from outside the pressure boundary. Complementary, typical tube - support contact conditions were analyzed and the principal variables affecting their mutual interaction determined. In addition, a simple device which allows performing fretting wear testing on steam generator tubes in air at room temperature was fabricated and the feasibility of a quantitative assessment of different aspects related with the fretting induced damage was explored. Characterization techniques available at Centro Atomico Bariloche, like light microscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX) and surface damage analysis by optic profilometry were shown to be appropriate for this aim. The designed facility will allow evaluating fretting damage of tubes - support combinations that might be used on the steam generator of the prototype reactor CAREM-25. It is also expected it could be applied to characterize fretting severity in other applications (nuclear fuel elements) (author)

  17. Dual-Beam Antenna Design for Autonomous Sensor Network Applications

    Directory of Open Access Journals (Sweden)

    Jean-Marie Floc'h

    2012-01-01

    Full Text Available This paper describes our contribution in the ANR project called CAPNET dedicated to the site security (autonomous sensor network. The network is autonomous in term of energy and it is very easy to deploy on the site (the time to deploy each node of the network is around 10 minutes. The first demonstrator was deployed in the fire base station of Brest, France with 10 nodes with a security perimeter around 1.5 km. Our contribution takes place in the field of antennas, with the development of two systems: a single-beam antenna reserved for the supervisor or the last node of the network, and a dual-beam antenna dedicated to the node in linear configuration. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT. The antennas have been designed and successfully measured.

  18. Improving brightness and photostability of green and red fluorescent proteins for live cell imaging and FRET reporting

    OpenAIRE

    Bajar, Bryce T.; Wang, Emily S.; Lam, Amy J.; Kim, Bongjae B.; Jacobs, Conor L.; Howe, Elizabeth S.; Davidson, Michael W.; Lin, Michael Z.; Chu, Jun

    2016-01-01

    Many genetically encoded biosensors use F?rster resonance energy transfer (FRET) to dynamically report biomolecular activities. While pairs of cyan and yellow fluorescent proteins (FPs) are most commonly used as FRET partner fluorophores, respectively, green and red FPs offer distinct advantages for FRET, such as greater spectral separation, less phototoxicity, and lower autofluorescence. We previously developed the green-red FRET pair Clover and mRuby2, which improves responsiveness in intra...

  19. MnO2 nanosheet mediated "DD-A" FRET binary probes for sensitive detection of intracellular mRNA.

    Science.gov (United States)

    Ou, Min; Huang, Jin; Yang, Xiaohai; Quan, Ke; Yang, Yanjing; Xie, Nuli; Wang, Kemin

    2017-01-01

    The donor donor-acceptor (DD-A) FRET model has proven to have a higher FRET efficiency than donor-acceptor acceptor (D-AA), donor-acceptor (D-A), and donor donor-acceptor acceptor (DD-AA) FRET models. The in-tube and in-cell experiments clearly demonstrate that the "DD-A" FRET binary probes can indeed increase the FRET efficiency and provide higher imaging contrast, which is about one order of magnitude higher than the ordinary "D-A" model. Furthermore, MnO 2 nanosheets were employed to deliver these probes into living cells for intracellular TK1 mRNA detection because they can adsorb ssDNA probes, penetrate across the cell membrane and be reduced to Mn 2+ ions by intracellular GSH. The results indicated that the MnO 2 nanosheet mediated "DD-A" FRET binary probes are capable of sensitive and selective sensing gene expression and chemical-stimuli changes in gene expression levels in cancer cells. We believe that the MnO 2 nanosheet mediated "DD-A" FRET binary probes have the potential as a simple but powerful tool for basic research and clinical diagnosis.

  20. Optical Fiber Demodulation System with High Performance for Assessing Fretting Damage of Steam Generator Tubes.

    Science.gov (United States)

    Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie; Xi, Zhide

    2018-01-12

    In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT) modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms.

  1. Optical Fiber Demodulation System with High Performance for Assessing Fretting Damage of Steam Generator Tubes

    Directory of Open Access Journals (Sweden)

    Peijian Huang

    2018-01-01

    Full Text Available In order to access the fretting damage of the steam generator tube (SGT, a fast fiber Fabry-Perot (F-P non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms.

  2. An ad-hoc fretting wear tribotester design for thin steel wires

    Directory of Open Access Journals (Sweden)

    Llavori Iñigo

    2018-01-01

    Full Text Available Steel wire ropes experience fretting wear damage when the rope runs over a sheave promoting an oscillatory motion between the wires. Consequently, wear scars appear between the contacting wires leading to an increase of the stress field and the following rupture of the wires due to fatigue. That is why the understanding and prediction of the fretting wear phenomena of thin wires is fundamental in order to improve the performance of steel wire ropes. The present research deals with the design of an ad-hoc fretting wear test machine for thin wires. The test apparatus is designed for testing thin wires with a maximum diameter of 1.0 mm, at slip amplitudes ranging from 5 to 300 μm, crossing angle between 0-90°, and contacting force ranging from 0,5 to 5 N. The working principle of displacement amplitude and contacting force as well as the crossing angle between the wires are described. Preliminary studies for understanding the fretting wear characteristics are presented, analysing 0.45 mm diameter cold-drawn eutectoid carbon steel (0.8% C wires (tensile strength higher than 3000 MPa.

  3. Single-molecule three-color FRET with both negligible spectral overlap and long observation time.

    Directory of Open Access Journals (Sweden)

    Sanghwa Lee

    Full Text Available Full understanding of complex biological interactions frequently requires multi-color detection capability in doing single-molecule fluorescence resonance energy transfer (FRET experiments. Existing single-molecule three-color FRET techniques, however, suffer from severe photobleaching of Alexa 488, or its alternative dyes, and have been limitedly used for kinetics studies. In this work, we developed a single-molecule three-color FRET technique based on the Cy3-Cy5-Cy7 dye trio, thus providing enhanced observation time and improved data quality. Because the absorption spectra of three fluorophores are well separated, real-time monitoring of three FRET efficiencies was possible by incorporating the alternating laser excitation (ALEX technique both in confocal microscopy and in total-internal-reflection fluorescence (TIRF microscopy.

  4. EXPERIMENTAL INVESTIGTION OF THE FRETTING PHENOMENON-DEPENDENCE OF NUMBERS CYCLES

    Directory of Open Access Journals (Sweden)

    Ştefan GHIMISI

    2014-12-01

    Full Text Available The present paper argues that adhesion forces and elastic deformation in the contact zone may contribute significantly to the relative displacement during fretting of metals. A simultaneously applied tangential force and normal into contact appears a adhesion force. A tangential force whose magnitude is less equal on greater than the force of limiting friction will not give rise on give rise to a sliding motion.It is determined the energy loss dissipated per fretting cycle.

  5. Parallel multispot smFRET analysis using an 8-pixel SPAD array

    Science.gov (United States)

    Ingargiola, A.; Colyer, R. A.; Kim, D.; Panzeri, F.; Lin, R.; Gulinatti, A.; Rech, I.; Ghioni, M.; Weiss, S.; Michalet, X.

    2012-02-01

    Single-molecule Förster resonance energy transfer (smFRET) is a powerful tool for extracting distance information between two fluorophores (a donor and acceptor dye) on a nanometer scale. This method is commonly used to monitor binding interactions or intra- and intermolecular conformations in biomolecules freely diffusing through a focal volume or immobilized on a surface. The diffusing geometry has the advantage to not interfere with the molecules and to give access to fast time scales. However, separating photon bursts from individual molecules requires low sample concentrations. This results in long acquisition time (several minutes to an hour) to obtain sufficient statistics. It also prevents studying dynamic phenomena happening on time scales larger than the burst duration and smaller than the acquisition time. Parallelization of acquisition overcomes this limit by increasing the acquisition rate using the same low concentrations required for individual molecule burst identification. In this work we present a new two-color smFRET approach using multispot excitation and detection. The donor excitation pattern is composed of 4 spots arranged in a linear pattern. The fluorescent emission of donor and acceptor dyes is then collected and refocused on two separate areas of a custom 8-pixel SPAD array. We report smFRET measurements performed on various DNA samples synthesized with various distances between the donor and acceptor fluorophores. We demonstrate that our approach provides identical FRET efficiency values to a conventional single-spot acquisition approach, but with a reduced acquisition time. Our work thus opens the way to high-throughput smFRET analysis on freely diffusing molecules.

  6. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    International Nuclear Information System (INIS)

    Zhang, P.; Lee, K.H.; Lee, C.H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

  7. Fretting and Corrosion Damage in Taper Adapter Sleeves for Ceramic Heads: A Retrieval Study.

    Science.gov (United States)

    MacDonald, Daniel W; Chen, Antonia F; Lee, Gwo-Chin; Klein, Gregg R; Mont, Michael A; Kurtz, Steven M; Cates, Harold E; Kraay, Matthew J; Rimnac, Clare M

    2017-09-01

    During revision surgery with a well-fixed stem, a titanium sleeve can be used in conjunction with a ceramic head to achieve better stress distribution across the taper surface. In vitro testing suggests that corrosion is not a concern in sleeved ceramic heads; however, little is known about the in vivo fretting corrosion of the sleeves. The purpose of this study was to investigate fretting corrosion in sleeved ceramic heads in retrieved total hip arthroplasties. Thirty-seven sleeved ceramic heads were collected during revision. The femoral heads and sleeves were implanted 0.0-3.3 years. The implants were revised predominantly for instability, infection, and loosening. Fifty percent of the retrievals were implanted during a primary surgery. Fretting corrosion was assessed using the Goldberg-Higgs semiquantitative scoring system. Mild-to-moderate fretting corrosion scores (score = 2-3) were observed in 92% of internal tapers, 19% of external tapers, and 78% of the stems. Severe fretting corrosion was observed in 1 stem trunnion that was previously retained during revision surgery and none of the retrieved sleeves. There was no difference in corrosion damage of sleeves used in primary or revision surgery. The fretting corrosion scores in this study were predominantly mild and lower than reported fretting scores of cobalt-chrome heads in metal-on-polyethylene bearings. Although intended for use in revisions, we found that the short-term in vivo corrosion behavior of the sleeves was similar in both primary and revision surgery applications. From an in vivo corrosion perspective, sleeves are a reasonable solution for restoring the stem taper during revision surgery. Copyright © 2017. Published by Elsevier Inc.

  8. Experimental and Numerical Investigations of Fretting Fatigue Behavior for Steel Q235 Single-Lap Bolted Joints

    Directory of Open Access Journals (Sweden)

    Yazhou Xu

    2016-01-01

    Full Text Available This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit the S-N curve. SEM (scanning electron microscope was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD-N relationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints.

  9. Fretting wear characteristic tests of X2-GEN midgrid for SMART under a FIV rod trace

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Lee, Kang Hee; Kim, Jae Yong; Kim, Hyung Kyu [KAERI, Daejeon (Korea, Republic of)

    2011-12-15

    The KEPCO Nuclear Fuel Co. requested the fretting wear characteristic tests of a X2-GEN midgrid under a FIV rod trace at room temperature air. The following results were obtained for the fretting wear test. {center_dot} Fretting wear tests under a FIV rod trace Based on the result of the fretting wear tests of the X2-GEN and 17ACE7 1x1 mid-grid under a FIV rod trace, X2-GEN mid-grid showed a slightly severe wear volume rather than 17ACE7 spring. But, maximum wear depth shows an opposite behavior. This is due to spring shape effect. The fretting wear mechanisms at each mid-grid were influenced by each spring shape, that are depended on the different impacting behavior under a FIV rod motion. Up to 5x105 cycles, wear characteristics of each mid-grid shows a relatively similar wear rate. Consequently, it is necessary to further study for examining exact fretting wear behavior under a FIV rod tra

  10. Homo-FRET imaging as a tool to quantify protein and lipid clustering.

    Science.gov (United States)

    Bader, Arjen N; Hoetzl, Sandra; Hofman, Erik G; Voortman, Jarno; van Bergen en Henegouwen, Paul M P; van Meer, Gerrit; Gerritsen, Hans C

    2011-02-25

    Homo-FRET, Förster resonance energy transfer between identical fluorophores, can be conveniently measured by observing its effect on the fluorescence anisotropy. This review aims to summarize the possibilities of fluorescence anisotropy imaging techniques to investigate clustering of identical proteins and lipids. Homo-FRET imaging has the ability to determine distances between fluorophores. In addition it can be employed to quantify cluster sizes as well as cluster size distributions. The interpretation of homo-FRET signals is complicated by the fact that both the mutual orientations of the fluorophores and the number of fluorophores per cluster affect the fluorescence anisotropy in a similar way. The properties of the fluorescence probes are very important. Taking these properties into account is critical for the correct interpretation of homo-FRET signals in protein- and lipid-clustering studies. This is be exemplified by studies on the clustering of the lipid raft markers GPI and K-ras, as well as for EGF receptor clustering in the plasma membrane. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Experimental fretting-wear studies of steam generator materials

    International Nuclear Information System (INIS)

    Fisher, N.J.; Chow, A.B.; Weckwerth, M.K.

    1994-01-01

    Flow-induced vibration of steam generator tubes results in fretting-wear damage due to impacting and rubbing of the tubes against their supports. This damage can be predicted by computing tube response to flow-induced excitation forces using analytical techniques, and then relating this response to resultant wear damage using experimentally-derived wear coefficients. Fretting-wear of steam generator materials has been studied experimentally at Chalk River Laboratories for two decades. Tests are conducted in machines that simulate steam generator environmental conditions and tube-to-support dynamic interactions. Different tube and support materials, tube-to-support clearances and tube support geometries have been studied. As well, the effect of environmental conditions, such as temperature, oxygen content, pH and chemistry control additive, have been investigated. Early studies showed that damage was related to contact force as long as other parameters, such as geometry and motion were held constant. Later studies have shown that damage is related to a parameter called work-rate, which combines both contact force and sliding distance. Results of short- and long-term fretting-wear tests for CANDU steam generator materials at realistic environmental conditions are presented. These results demonstrate that work-rate is appropriate correlating parameter for impact-sliding interaction

  12. Aspects of fretting wear of sprayed cermet coatings

    International Nuclear Information System (INIS)

    Chivers, T.C.

    1985-01-01

    Two experimental fretting programmes which investigated aspects of fretting wear of sprayed cermet coatings are reviewed. These programmes were conducted in support of components used in the advanced gas-cooled reactor. It is speculated that the results from these programmes are compatible with a simple two-stage wear model. This model assumes that an initial wear process occurs which is dominated by an interlocking and removal of asperities. Such a phase will be dependent on the superficial contact areas and possibly the interfacial load, but the latter aspect is not considered. This initial wear is of very short duration and is followed by a mild, oxidative, wear mode. Coatings data are also compared with those for structural steels. In short-term low temperature tests it appears that structural steels have comparable performance with the cermet coatings but it is argued that this is an artefact of the wear process. However, at high temperatures (600 0 C) wear of stainless steel could not be determined, the specimens showing a net weight gain. It is concluded that for in-reactor fretting applications cermet coatings will have advantages over structural steels at low temperatures. Even in high temperature regions some operation at low temperatures is experienced and consequently cermet coatings may be useful here also. (orig.)

  13. Some theory of a dual-polarization interferometer for sensor applications

    International Nuclear Information System (INIS)

    Abram, R A; Brand, S

    2015-01-01

    It is shown that by making straightforward approximations it is possible to simplify the analysis of the measurements of a well-established dual-waveguide interferometer for sensor applications. In particular we derive approximate algebraic formulae for the mode phase shifts that are measured in the interferometric sensor when a layer of the entity to be detected is deposited. Knowledge of the shifts of both the TE and TM mode phases allows the deduction of both the thickness and refractive index of a homogeneous deposited layer, and the formulae derived make that possible with significantly reduced numerical computation. More generally the algebraic formulae and the ease with which numerical results can be obtained for a wide range of layer parameter combinations provide opportunities to improve our understanding of device behaviour. In an application of the theory to a specific practical structure, the numerical results show that the ratio of the TE and TM mode phase shifts varies linearly with deposited layer refractive index but is only weakly dependent on layer thickness, as has been observed previously in some experiments. The numerical results are interpreted using the theory and a simple formula describing the linear dependence of phase shift ratio on deposited layer refractive index is derived. (paper)

  14. Fluorescent Protein-Based Ca2+ Sensor Reveals Global, Divalent Cation-Dependent Conformational Changes in Cardiac Troponin C.

    Directory of Open Access Journals (Sweden)

    Myriam A Badr

    Full Text Available Cardiac troponin C (cTnC is a key effector in cardiac muscle excitation-contraction coupling as the Ca2+ sensing subunit responsible for controlling contraction. In this study, we generated several FRET sensors for divalent cations based on cTnC flanked by a donor fluorescent protein (CFP and an acceptor fluorescent protein (YFP. The sensors report Ca2+ and Mg2+ binding, and relay global structural information about the structural relationship between cTnC's N- and C-domains. The sensors were first characterized using end point titrations to decipher the response to Ca2+ binding in the presence or absence of Mg2+. The sensor that exhibited the largest responses in end point titrations, CTV-TnC, (Cerulean, TnC, and Venus was characterized more extensively. Most of the divalent cation-dependent FRET signal originates from the high affinity C-terminal EF hands. CTV-TnC reconstitutes into skinned fiber preparations indicating proper assembly of troponin complex, with only ~0.2 pCa unit rightward shift of Ca2+-sensitive force development compared to WT-cTnC. Affinity of CTV-TnC for divalent cations is in agreement with known values for WT-cTnC. Analytical ultracentrifugation indicates that CTV-TnC undergoes compaction as divalent cations bind. C-terminal sites induce ion-specific (Ca2+ versus Mg2+ conformational changes in cTnC. Our data also provide support for the presence of additional, non-EF-hand sites on cTnC for Mg2+ binding. In conclusion, we successfully generated a novel FRET-Ca2+ sensor based on full length cTnC with a variety of cellular applications. Our sensor reveals global structural information about cTnC upon divalent cation binding.

  15. Molecularly imprinted fluorescent probe based on FRET for selective and sensitive detection of doxorubicin

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhifeng, E-mail: 897061147@qq.com [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Deng, Peihong; Li, Junhua [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Xu, Li [Department of Applied Chemistry, College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Tang, Siping [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China)

    2017-04-15

    Highlights: • FRET-based molecularly imprinted probe for detection of doxorubicin was prepared. • The detection limit of the probe was 13.8 nM for doxorubicin. • The FRET-based probe had a higher selectivity for the template than ordinary MIMs. - Abstract: In this work, a new type of fluorescent probe for detection of doxorubicin has been constructed by the combined use of fluorescence resonance energy transfer (FRET) technology and molecular imprinting technique (MIT). Using doxorubicin as the template, the molecularly imprinted polymer thin layer was fabricated on the surfaces of carbon dot (CD) modified silica by sol-gel polymerization. The excitation energy of the fluorescent donor (CDs) could be transferred to the fluorescent acceptor (doxorubicin). The FRET based fluorescent probe demonstrated high sensitivity and selectivity for doxorubicin. The detection limit was 13.8 nM. The fluorescent probe was successfully applied for detecting doxorubicin in doxorubicin-spiked plasmas with a recovery of 96.8–103.8%, a relative standard deviation (RSD) of 1.3–2.8%. The strategy for construction of FRET-based molecularly imprinted materials developed in this work is very promising for analytical applications.

  16. Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

    Science.gov (United States)

    Cheng, Rui; Xia, Li

    2016-11-15

    It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

  17. Residual stress relaxation due to fretting fatigue in shot peened surfaces of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Martinez, S.A.; Blodgett, M.P.; Mall, S.; Sathish, S.; Namjoshi, S.

    2003-01-01

    Fretting fatigue occurs at locations where the materials are sliding against each other under load. In order to enhance the fatigue life under fretting conditions the surface of the component is shot peened. In general, the shot peening process produces a compressive stress on the surface of the material, thereby increasing the resistance of the material to crack initiation. This paper presents the relaxation of residual stress caused during fretting fatigue. X-ray diffraction has been utilized as the method to measure residual stress in fretting fatigued samples of Ti-6Al-4V

  18. Calculated and experimental research of WWER-1000 assembly vibration and fretting damage

    International Nuclear Information System (INIS)

    Drozdov, Y.; Afanasyev, A.; Makarov, V.; Tutnov, A.; Tutnov, A.; Alekseev, E.

    2008-01-01

    The report covers the methods and results of the latest analytical and experimental studies of fretting corrosion and natural vibrations of a WWER-1000 reactor fuel assemblies (FA). The process of fretting-corrosion was investigated using a multi-specimen facility that simulated fragments of fuel rod-to-spacer grid and lower support grid mating units. A computational model was developed for vibrations in the mechanical system of a fuel rod fragment and a spacer grid fragment. A calculational and experimental modal analysis of a FA was performed. Natural frequencies, modes and decrements of FA vibrations were determined and a satisfactory coincidence of analytical and experimental results was obtained. The assessment of fretting-corrosion process dynamics was made and its dependences on operational factors were obtained. (authors)

  19. Approximate stresses in 2-D flat elastic contact fretting problems

    Science.gov (United States)

    Urban, Michael Rene

    Fatigue results from the cyclic loading of a solid body. If the body subject to fatigue is in contact with another body and relative sliding motion occurs between these two bodies, then rubbing surface damage can accelerate fatigue failure. The acceleration of fatigue failure is especially important if the relative motion between the two bodies results in surface damage without excessive surface removal via wear. The situation just described is referred to as fretting fatigue. Understanding of fretting fatigue is greatly enhanced if the stress state associated with fretting can be characterized. For Hertzian contact, this can readily be done. Unfortunately, simple stress formulae are not available for flat body contact. The primary result of the present research is the development of a new, reasonably accurate, approximate closed form expression for 2-dimensional contact stresses which has been verified using finite element modeling. This expression is also combined with fracture mechanics to provide a simple method of determining when a crack is long enough to no longer be affected by the contact stress field. Lower bounds on fatigue life can then easily be calculated using fracture mechanics. This closed form expression can also be used to calculate crack propagation within the contact stress field. The problem of determining the cycles required to generate an initial crack and what to choose as an initial crack size is unresolved as it is in non-fretting fatigue.

  20. A Study on Surface Modification of Al7075-T6 Alloy against Fretting Fatigue Phenomenon

    Directory of Open Access Journals (Sweden)

    E. Mohseni

    2014-01-01

    Full Text Available Aircraft engines, fuselage, automobile parts, and energy saving strategies in general have promoted the interest and research in the field of lightweight materials, typically on alloys based on aluminum. Aluminum alloy itself does not have suitable wear resistance; therefore, it is necessary to enhance surface properties for practical applications, particularly when aluminum is in contact with other parts. Fretting fatigue phenomenon occurs when two surfaces are in contact with each other and one or both parts are subjected to cyclic load. Fretting drastically decreases the fatigue life of materials. Therefore, investigating the fretting fatigue life of materials is an important subject. Applying surface modification methods is anticipated to be a supreme solution to gradually decreasing fretting damage. In this paper, the authors would like to review methods employed so far to diminish the effect of fretting on the fatigue life of Al7075-T6 alloy. The methods include deep rolling, shot peening, laser shock peening, and thin film hard coatings. The surface coatings techniques are comprising physical vapor deposition (PVD, hard anodizing, ion-beam-enhanced deposition (IBED, and nitriding.

  1. A novel dual-functional MEMS sensor integrating both pressure and temperature units

    Energy Technology Data Exchange (ETDEWEB)

    Chen Tao; Zhang Zhaohua; Ren Tianling; Miao Gujin; Zhou Changjian; Lin Huiwang; Liu Litian, E-mail: RenTL@tsinghua.edu.c [National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2010-07-15

    This paper proposes a novel miniature dual-functional sensor integrating both pressure and temperature sensitive units on a single chip. The device wafer of SOI is used as a pizeoresistive diaphragm which features excellent consistency in thickness. The conventional anisotropic wet etching has been abandoned, while ICP etching has been employed to etch out the reference cave to minimize the area of individual device in the way that the 57.4{sup 0} slope has been eliminated. As a result, the average cost of the single chip is reduced. Two PN junctions with constant ratio of the areas of depletion regions have also been integrated on the same chip to serve as a temperature sensor, and each PN junction shows high linearity over -40 to 100 {sup 0}C and low power consumption. The iron implanting process for PN junction is exactly compatible with the piezoresistor, with no additional expenditure. The pressure sensitivity is 86 mV/MPa, while temperature sensitivity is 1.43 mV/{sup 0}C, both complying with the design objective.

  2. A novel dual-functional MEMS sensor integrating both pressure and temperature units

    International Nuclear Information System (INIS)

    Chen Tao; Zhang Zhaohua; Ren Tianling; Miao Gujin; Zhou Changjian; Lin Huiwang; Liu Litian

    2010-01-01

    This paper proposes a novel miniature dual-functional sensor integrating both pressure and temperature sensitive units on a single chip. The device wafer of SOI is used as a pizeoresistive diaphragm which features excellent consistency in thickness. The conventional anisotropic wet etching has been abandoned, while ICP etching has been employed to etch out the reference cave to minimize the area of individual device in the way that the 57.4 0 slope has been eliminated. As a result, the average cost of the single chip is reduced. Two PN junctions with constant ratio of the areas of depletion regions have also been integrated on the same chip to serve as a temperature sensor, and each PN junction shows high linearity over -40 to 100 0 C and low power consumption. The iron implanting process for PN junction is exactly compatible with the piezoresistor, with no additional expenditure. The pressure sensitivity is 86 mV/MPa, while temperature sensitivity is 1.43 mV/ 0 C, both complying with the design objective.

  3. Ratiometric FRET-based detection of DNA and micro-RNA on the surface using TIRF detection

    International Nuclear Information System (INIS)

    Matveeva, Evgenia G.; Gryczynski, Zygmunt; Stewart, Donald R.; Gryczynski, Ignacy

    2010-01-01

    A new FRET-based method for the ratiometric detection of DNA oligomers on a surface using TIRF detection mode is reported. The dual-labeled system consisting of two hybridized oligomers, Cy3oligoY:Cy5oligoX was immobilized on the surface, and the total internal reflection fluorescence (TIRF) was used to detect emission signals from the surface. Two signals, green and red, which originated from the green donor Cy3 and the red acceptor Cy5, have been simultaneously detected. When the target single-stranded complimentary oligomer was present in the solution, this oligomer replaced the Cy3oligoY in the donor:acceptor complex on the surface and the ratio of red-to-green signal was dramatically changed. This detection scheme is generally applicable to the detection of DNA or RNA on a surface.

  4. Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

    Science.gov (United States)

    Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

    2015-09-01

    Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

  5. FRET-based modified graphene quantum dots for direct trypsin quantification in urine

    Energy Technology Data Exchange (ETDEWEB)

    Poon, Chung-Yan; Li, Qinghua [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Zhang, Jiali; Li, Zhongping [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Research Center of Environmental Science and Engineering, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Dong, Chuan [Research Center of Environmental Science and Engineering, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Lee, Albert Wai-Ming; Chan, Wing-Hong [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Li, Hung-Wing, E-mail: hwli@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong)

    2016-04-21

    A versatile nanoprobe was developed for trypsin quantification with fluorescence resonance energy transfer (FRET). Here, fluorescence graphene quantum dot is utilized as a donor while a well-designed coumarin derivative, CMR2, as an acceptor. Moreover, bovine serum albumin (BSA), as a protein model, is not only served as a linker for the FRET pair, but also a fluorescence enhancer of the quantum dots and CMR2. In the presence of trypsin, the FRET system would be destroyed when the BSA is digested by trypsin. Thus, the emission peak of the donor is regenerated and the ratio of emission peak of donor/emission peak of acceptor increased. By the ratiometric measurement of these two emission peaks, trypsin content could be determined. The detection limit of trypsin was found to be 0.7 μg/mL, which is 0.008-fold of the average trypsin level in acute pancreatitis patient's urine suggesting a high potential for fast and low cost clinical screening. - Highlights: • A FRET-based biosensor was developed for direct quantification of trypsin. • Fast and sensitive screening of pancreatic disease was facilitated. • The direct quantification of trypsin in urine samples was demonstrated.

  6. Surveillance of siRNA integrity by FRET imaging

    Science.gov (United States)

    Järve, Anne; Müller, Julius; Kim, Il-Han; Rohr, Karl; MacLean, Caroline; Fricker, Gert; Massing, Ulrich; Eberle, Florian; Dalpke, Alexander; Fischer, Roger; Trendelenburg, Michael F.; Helm, Mark

    2007-01-01

    Techniques for investigation of exogenous small interfering RNA (siRNA) after penetration of the cell are of substantial interest to the development of efficient transfection methods as well as to potential medical formulations of siRNA. A FRET-based visualization method including the commonplace dye labels fluorescein and tetramethylrhodamin (TMR) on opposing strands of siRNA was found compatible with RNA interference (RNAi). Investigation of spectral properties of three labelled siRNAs with differential FRET efficiencies in the cuvette, including pH dependence and FRET efficiency in lipophilic environments, identified the ratio of red and green fluorescence (R/G-ratio) as a sensitive parameter, which reliably identifies samples containing >90% un-degraded siRNA. Spectral imaging of siRNAs microinjected into cells showed emission spectra indistinguishable from those measured in the cuvette. These were used to establish a calibration curve for assessing the degradation state of siRNA in volume elements inside cells. An algorithm, applied to fluorescence images recorded in standard green and red fluorescence channels, produces R/G-ratio images of high spatial resolution, identifying volume elements in the cell with high populations of intact siRNA with high fidelity. To demonstrate the usefulness of this technique, the movement of intact siRNA molecules are observed after introduction into the cytosol by microinjection, standard transfection and lipofection with liposomes. PMID:17890733

  7. In vitro simulation of fretting-corrosion in hip implant modular junctions: The influence of pH.

    Science.gov (United States)

    Royhman, Dmitry; Patel, Megha; Jacobs, Joshua J; Wimmer, Markus A; Hallab, Nadim J; Mathew, Mathew T

    2018-02-01

    The fretting-corrosion behavior of mixed metal contacts is affected by various mechanical and electrochemical parameters. Crevice conditions at the junction and patient-specific pathologies can affect the pH of the prosthetic environment. The main objective of this study is to understand the effect of pH variation at the stem/head junction of the hip implant under fretting corrosion exposure. We hypothesized that pH will have a significant influence on the fretting-corrosion behavior hip implant modular junctions. A custom-made setup was used to evaluate the fretting corrosion behavior of hip implant modular junctions. A Newborn calf serum solution (30 g/L protein content) was used to simulate the synovial fluid environment. A sinusoidal fretting motion, with a displacement amplitude of +50 µm, was applied to the Ti alloy rod. The effects of pathology driven, periprosthetic pH variation were simulated at four different pH levels (3.0, 4.5, 6.0 and 7.6). Electrochemical and mechanical properties were evaluated before, during, and after the applied fretting motion. The impedance of the system was increased in response to the fretting motion. The hysteresis tangential load/displacement behavior was not affected by pH level. The worn surfaces of CoCrMo pins exhibited the presence of tribolayer or organic deposits, in the pH 4.5 group, which may explain the lower drop in potential and mass loss observed in that group. Mechanically dominated wear mechanisms, namely, adhesive wear was shown in the pH 7.6 group, which may account for a higher potential drop and metal content loss. This study suggests that the fretting-corrosion mechanisms in hip implant are affected by the pH levels of the surrounding environment and patient-specific factors. Copyright © 2017. Published by Elsevier Ltd.

  8. Reconstruction of calmodulin single-molecule FRET states, dye interactions, and CaMKII peptide binding by MultiNest and classic maximum entropy

    Science.gov (United States)

    DeVore, Matthew S.; Gull, Stephen F.; Johnson, Carey K.

    2013-08-01

    We analyzed single molecule FRET burst measurements using Bayesian nested sampling. The MultiNest algorithm produces accurate FRET efficiency distributions from single-molecule data. FRET efficiency distributions recovered by MultiNest and classic maximum entropy are compared for simulated data and for calmodulin labeled at residues 44 and 117. MultiNest compares favorably with maximum entropy analysis for simulated data, judged by the Bayesian evidence. FRET efficiency distributions recovered for calmodulin labeled with two different FRET dye pairs depended on the dye pair and changed upon Ca2+ binding. We also looked at the FRET efficiency distributions of calmodulin bound to the calcium/calmodulin dependent protein kinase II (CaMKII) binding domain. For both dye pairs, the FRET efficiency distribution collapsed to a single peak in the case of calmodulin bound to the CaMKII peptide. These measurements strongly suggest that consideration of dye-protein interactions is crucial in forming an accurate picture of protein conformations from FRET data.

  9. Reconstruction of Calmodulin Single-Molecule FRET States, Dye-Interactions, and CaMKII Peptide Binding by MultiNest and Classic Maximum Entropy.

    Science.gov (United States)

    Devore, Matthew S; Gull, Stephen F; Johnson, Carey K

    2013-08-30

    We analyze single molecule FRET burst measurements using Bayesian nested sampling. The MultiNest algorithm produces accurate FRET efficiency distributions from single-molecule data. FRET efficiency distributions recovered by MultiNest and classic maximum entropy are compared for simulated data and for calmodulin labeled at residues 44 and 117. MultiNest compares favorably with maximum entropy analysis for simulated data, judged by the Bayesian evidence. FRET efficiency distributions recovered for calmodulin labeled with two different FRET dye pairs depended on the dye pair and changed upon Ca 2+ binding. We also looked at the FRET efficiency distributions of calmodulin bound to the calcium/calmodulin dependent protein kinase II (CaMKII) binding domain. For both dye pairs, the FRET efficiency distribution collapsed to a single peak in the case of calmodulin bound to the CaMKII peptide. These measurements strongly suggest that consideration of dye-protein interactions is crucial in forming an accurate picture of protein conformations from FRET data.

  10. A Dual Electrochemical Sensor Based on a Test-strip Assay for the Quantitative Determination of Albumin and Creatinine.

    Science.gov (United States)

    Yasukawa, Tomoyuki; Kiba, Yuya; Mizutani, Fumio

    2015-01-01

    A dual-electrochemical sensor based on a test-strip assay with immunochemistry and enzyme reactions has been developed for the determination of albumin and creatinine. Each nitrocellulose membrane with an immobilization area of an anti-albumin antibody or three enzymes was prepared in the device with three working electrodes for measuring albumin, creatinine, and ascorbic acid, as well as an Ag/AgCl electrode used as a counter/pseudo-reference electrode. The reactions of three enzymes were initiated by flowing a solution containing creatinine to detect an oxidation current of hydrogen peroxide. A sandwich-type immunocomplex was formed by albumin and antibody labeled with glucose oxidase (GOx). Captured GOx catalyzed the reduction of Fe(CN)6(3-) to Fe(CN)6(4-), which was oxidized electrochemically to determine the captured albumin. The responses for creatinine and albumin increased with the concentrations in millimolar order and over the range 18.75 - 150 μg mL(-1), respectively. The present sensor would be a distinct demonstration for producing quantitative dual-assays for various biomolecules used for clinical diagnoses.

  11. An experimental study on the key fretting variables for flexible marine risers

    OpenAIRE

    O’Halloran, S.M.; Harte, A.M.; Shipway, P.H.; Leen, S.B.

    2018-01-01

    This paper presents an experimental investigation into the effects of contact conformity, contact pressure and displacement amplitude on the gross-slip fretting behaviour grease-lubricated cylinder-on-flat contacts in the context of flexible marine riser pressure armour wire, and compares behaviour with that observed in unlubricated conditions. Characterisation of friction and wear is critical to fretting fatigue life prediction in flexible risers since friction directly controls trailing-edg...

  12. Effect of mixed alloy combinations on fretting corrosion performance of spinal screw and rod implants.

    Science.gov (United States)

    Mali, Sachin A; Singh, Vaneet; Gilbert, Jeremy L

    2017-07-01

    Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern about mixing dissimilar metals in an implant because of fear of inducing corrosion. There is a lack of systematic studies on the effects of mixing metals on performance of spinal implants, especially in fretting corrosion conditions. Hence, the goal was to determine whether mixing stainless steel (SS316L), titanium alloy (Ti6Al4V) and cobalt chromium (CoCrMo) alloy components in a spinal implant leads to any increased risk of corrosion degradation. Spinal constructs consisting of single assembly screw-connector-rod components were tested using a novel short-term cyclic fretting corrosion test method. A total of 17 alloy component combinations (comprised of SS316L, Ti6Al4V-anodized and CoCrMo alloy for rod, screws and connectors) were tested under three anatomic orientations. Spinal constructs having all SS316L were most susceptible to fretting-initiated crevice corrosion attack and showed higher average fretting currents (∼25 - 30 µA), whereas constructs containing all Ti6Al4V components were less susceptible to fretting corrosion with average fretting currents in the range of 1 - 6 µA. Mixed groups showed evidence of fretting corrosion but they were not as severe as all SS316L group. SEM results showed evidence of severe corrosion attack in constructs having SS316L components. There also did not appear to be any galvanic effects of combining alloys together. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1169-1177, 2017. © 2016 Wiley Periodicals, Inc.

  13. Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

    Science.gov (United States)

    Bui, H.; Pham, T. B.; Nguyen, V. A.; Pham, V. D.; Do, T. C.; Nguyen, T. V.; Hoang, T. H. C.; Le, H. T.; Pham, V. H.

    2018-05-01

    Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5  ×  10‑4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

  14. Magnetic field sensor based on the Ampere's force using dual-polarization DBR fiber laser

    Science.gov (United States)

    Yao, Shuang; Zhang, Yang; Guan, Baiou

    2015-08-01

    A novel magnetic field sensor using distributed Bragg reflector (DBR) fiber laser by Ampere's force effect is proposed and experimentally demonstrated. The key sensing element, that is the dual-polarization DBR fiber laser, is fixed on the middle part of two copper plates which carry the current. Ampere's force is applied onto the coppers due to an external magnetic field generated by a DC solenoid. Thus, the lateral force from the coppers is converted to a corresponding beat frequency signal shift produced by the DBR laser. The electric current sensing is also realized by the same configuration and same principle simultaneously in an intuitive manner. Good agreement between the theory calculation and the experimental results is obtained, which shows a good linearity. This sensor's sensitivity to the magnetic field and to the electric current finally reaches ~258.92 kHz/mT and ~1.08727 MHz/A, respectively.

  15. Combined effects of fretting and pollutant particles on the contact resistance of the electrical connectors

    Directory of Open Access Journals (Sweden)

    Zhigang Kong

    2017-06-01

    Full Text Available Usually, when electrical connectors operate in vibration environments, fretting will be produced at the contact interfaces. In addition, serious environmental pollution particles will affect contact resistance of the connectors. The fretting will worsen the reliability of connectors with the pollutant particles. The combined effects of fretting and quartz particles on the contact resistance of the gold plating connectors are studied with a fretting test system. The results show that the frequencies have obvious effect on the contact resistance. The higher the frequency, the higher the contact resistance is. The quartz particles cause serious wear of gold plating, which make the nickel and copper layer exposed quickly to increase the contact resistance. Especially in high humidity environments, water supply certain adhesion function and make quartz particles easy to insert or cover the contact surfaces, and even cause opening resistance.

  16. The measurement of gas–liquid two-phase flows in a small diameter pipe using a dual-sensor multi-electrode conductance probe

    International Nuclear Information System (INIS)

    Zhai, Lu-Sheng; Bian, Peng; Han, Yun-Feng; Gao, Zhong-Ke; Jin, Ning-De

    2016-01-01

    We design a dual-sensor multi-electrode conductance probe to measure the flow parameters of gas–liquid two-phase flows in a vertical pipe with an inner diameter of 20 mm. The designed conductance probe consists of a phase volume fraction sensor (PVFS) and a cross-correlation velocity sensor (CCVS). Through inserting an insulated flow deflector in the central part of the pipe, the gas–liquid two-phase flows are forced to pass through an annual space. The multiple electrodes of the PVFS and the CCVS are flush-mounted on the inside of the pipe wall and the outside of the flow deflector, respectively. The geometry dimension of the PVFS is optimized based on the distribution characteristics of the sensor sensitivity field. In the flow loop test of vertical upward gas–liquid two-phase flows, the output signals from the dual-sensor multi-electrode conductance probe are collected by a data acquisition device from the National Instruments (NI) Corporation. The information transferring characteristics of local flow structures in the annular space are investigated using the transfer entropy theory. Additionally, the kinematic wave velocity is measured based on the drift velocity model to investigate the propagation behavior of the stable kinematic wave in the annular space. Finally, according to the motion characteristics of the gas–liquid two-phase flows, the drift velocity model based on the flow patterns is constructed to measure the individual phase flow rate with higher accuracy. (paper)

  17. The Necessity of a New Type Test Rig for the Development of an Evaluation Method in Grid Fretting Problems

    International Nuclear Information System (INIS)

    Lee, Young-Ho; Kim, Hyung-Kyu

    2007-01-01

    A grid fretting problem is recognized as one of the most important degradation mechanisms even though the examination results of fretting experiments could be applied to the development and design of spacer grid structures. This is because it is difficult to develop a fretting wear model for a grid fretting problem due to the various wear mechanisms involved according to the mechanical and environmental variables, the contact condition with a spring/dimple and the material properties. A number of spring shapes has been developed in KAERI and their performance tests such as fretting wear, flow-induced vibration (FIV) tests, etc. have been carried out from a part unit to a full assembly scale. From the unit part fretting test results, one of the noticeable results is that the contacting force (normal load) was gradually decreased with increasing number of fretting cycles due to a depth increase and this behavior was closely related to the contacting spring shape. When considering the actual contact condition between a fuel rod and a spring/dimple, if a fretting wear progresses due to a FIV under a specific normal load exerted on the fuel rod by an elastic deformation of the spring, the contacting force between the fuel rod and dimple that are located in the opposite side should be decreased. Consequently, an evaluation of developed spacer grids against fretting wear damage should be performed with the results of 1x1 cell unit experiments because a contacting force is one of the most important variables that influences a fretting wear mechanism. The discussion was focused on the development procedure of a new test rig and its performance by using a 1x1 cell unit test rig. (authors)

  18. Fretting wear damage of HexTOOL{sup TM} composite depending on the different fibre orientations

    Energy Technology Data Exchange (ETDEWEB)

    Terekhina, S; Salvia, M; Fouvry, S [Laboratoire de Tribologie et Dynamique des Systemes, UMR CNRS ECL ENISE ENSMSE 5513, Ecole Centrale de Lyon, 69134 Ecully cedex (France); Malysheva, G; Tarasova, T, E-mail: svetlana.terekhina@ec-lyon.fr, E-mail: svetlanaterekhina@yandex.ru [Bauman Moscow State Technical University, 105005 Moscow, 5, 2nd Baumanskaya str (Russian Federation)

    2009-09-15

    The composites have drawn considerable interest in the mould processes. The vibrations and fatigue stresses induced in the moulds made evident to characterize the composite HexTOOL{sup TM} under fretting conditions. Fretting is a small-amplitude oscillatory motion between contacting surfaces. The running conditions fretting maps (RCFM) of composite at ambient conditions were established. The influence of different fiber orientations of HexTOOL{sup TM} composite on the wear kinetics was shown. An energy wear approach was developed. According to results of dynamic mechanical analysis (DMA), the viscoelastic properties of composite material were obtained.

  19. An overview of the Canadian program to investigate vibration and fretting in nuclear fuel assemblies

    International Nuclear Information System (INIS)

    Oldaker, I.E.; Lane, A.D.; Forrest, C.F.

    The development of a model that would allow the fuel designer to predict the occurrence of fretting could materially reduce the amount of development testing of a new fuel design. To achieve this, we are working in several areas: to identify and measure the phenomena that excite fuel to vibrate, and to study their relation to reactor design features; to predict the vibratory response of a fuel assembly as a function of its design and environment, and; to study the relationship between vibration and fretting to determine when vibration results in fretting. (author)

  20. Protecting AREVA ATRIUM™ BWR fuel from debris fretting failure

    International Nuclear Information System (INIS)

    Cole, Steven E.; Garner, Norman L.; Lippert, Hans-Joachim; Graebert, Rüdiger; Mollard, Pierre; Hahn, Gregory C.

    2014-01-01

    Historically, debris fretting has been the leading cause of fuel rod failure in BWR fuel assemblies, costing the industry millions of dollars in lost generation and negatively impacting the working area of plant site personnel. In this paper the focus will be on recent BWR fuel product innovation designed to eliminate debris related failures. Experience feedback from more than three decades of operation history with non-line-of-sight FUELGUARD™ lower tie plate debris filters will be presented. The development and relative effectiveness of successive generations of filtration technology will be discussed. It will be shown that modern, state of the art debris filters are an effective defense against debris fretting failure. Protective measures extend beyond inlet nozzle debris filters. The comprehensive debris resistance features built into AREVA’s newest fuel design, the ATRIUM™ 11, reduce the overall risk of debris entrapment as well as providing a degree of protection from debris that may fall down on the fuel assembly from above, e.g., during refueling operations. The positive recent experience in a debris sensitive plant will be discussed showing that the combination of advanced fuel technology and a robust foreign material exclusion program at the reactor site can eliminate the debris fretting failure mechanism. (author)

  1. Sensitivity-Enhancement of FRET Immunoassays by Multiple-Antibody Conjugation on Quantum Dots.

    Science.gov (United States)

    Annio, Giacomo; Jennings, Travis; Tagit, Oya; Hildebrandt, Niko

    2018-05-23

    Quantum dots (QDs) are not only advantageous for color-tuning, improved brightness, and high stability, but their nanoparticle surfaces also allow for the attachment of many biomolecules. Because IgG antibodies (ABs) are in the same size range of biocompatible QDs and the AB orientation after conjugation to the QD is often random, it is difficult to predict if few or many ABs per QD will lead to an efficient AB-QD conjugate. This is particularly true for homogeneous Förster resonance energy transfer (FRET) sandwich immunoassays, for which the ABs on the QD must bind a biomarker that needs to bind a second AB-FRET-conjugate. Here, we investigate the performance of Tb-to-QD FRET immunoassays against total prostate specific antigen (TPSA) by changing the number of ABs per QD while leaving all the other assay components unchanged. We first characterize the AB-QD conjugation by various spectroscopic, microscopic, and chromatographic techniques and then quantify the TPSA immunoassay performance regarding sensitivity, limit of detection, and dynamic range. Our results show that an increasing conjugation ratio leads to significantly enhanced FRET immunoassays. These findings will be highly important for developing QD-based immunoassays in which the concentrations of both ABs and QDs can significantly influence the assay performance.

  2. Investigation of fretting behaviour in pressure armour layers of flexible pipes

    Science.gov (United States)

    Don Rasika Perera, Solangarachchige

    The incidence of fretting damage in the pressure armour wires of flexible pipes used in offshore oil explorations has been investigated. A novel experimental facility which is capable of simulating nub and valley contact conditions of interlocking wire winding with dynamic slip, representative of actual pipe loading, has been developed. The test set-up is equipped with a state of the art data acquisition system and a controller with transducers to measure and control the normal load, slip amplitude and friction force at the contact, in addition to the hoop stress in the wire. Tests were performed with selected loading and the fretted regions were examined using optical microscopy techniques. Results show that the magnitude of contact loading and the slip amplitude have a distinct influence on surface damage. Surface cracks originated from a fretting scar were observed at high contact loads in mixed slip sliding while surface damage predominantly due to wear was observed under gross slip. The position of surface cracks and the wear profile have been related to the contact pressure distribution. The evolution of friction force and surface damage under different slip and normal pressure conditions has been analysed. A fracture mechanics based numerical procedure has been developed to analyse the fretting damage behaviour. A severity parameter is proposed in order to ascertain whether the crack growth is in mode I or mode II cracking. The analysis show the influence of mode II cracking in the early stages of crack growth following which the crack deviates in the mode I direction making mode I the dominant crack propagation mechanism. The crack path determined by the numerical procedure correlates well with the experimental results. A numerical analysis was carried out for the fretting fatigue condition where a cyclic bulk stress superimposes with the friction force. The analysis correlates well with short crack growth behaviour. The analysis confirms that fretting is a

  3. Fluorescence resonance energy transfer (FRET) in chemistry and ...

    Indian Academy of Sciences (India)

    Förster distance dependence of the FRET rate. SANGEETA SAINI,1 HARJINDER SINGH2 and BIMAN BAGCHI1,*. 1Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012. 2Permanent address: Department of ...

  4. A combined wear-fatigue design methodology for fretting in the pressure armour layer of flexible marine risers

    OpenAIRE

    O'Halloran, S.M.; Shipway, P.H.; Connaire, A.D.; Leen, Sean B.; Harte, A.M.

    2017-01-01

    This paper presents a combined experimental and computational methodology for fretting wear-fatigue prediction of pressure armour wire in flexible marine risers. Fretting wear, friction and fatigue parameters of pressure armour material have been characterised experimentally. A combined fretting wear-fatigue finite element model has been developed using an adaptive meshing technique and the effect of bending-induced tangential slip has been characterised. It has been shown that a surface dama...

  5. Fretting-corrosion behavior in hip implant modular junctions: The influence of friction energy and pH variation.

    Science.gov (United States)

    Royhman, Dmitry; Patel, Megha; Runa, Maria J; Wimmer, Markus A; Jacobs, Joshua J; Hallab, Nadim J; Mathew, Mathew T

    2016-09-01

    Recently, there has been increasing concern in the orthopedic community over the use of hip implant modular devices due to an increasing number of reports of early failure, failure that has been attributed to fretting-corrosion at modular interfaces. Much is still unknown about the electrochemical and mechanical degradation mechanisms associated with the use of such devices. Accordingly, the purpose of our study was to develop a methodology for testing the fretting-corrosion behavior of modular junctions. A fretting-corrosion apparatus was used to simulate the fretting-corrosion conditions of a CoCrMo hip implant head on a Ti6Al4V hip implant stem. The device features two perpendicularly-loaded CoCrMo pins that articulated against a Ti6Al4V rod. A sinusoidal fretting motion was applied to the rod at various displacement amplitudes (25, 50, 100, 150 and 200μm) at a constant load of 200N. Bovine calf serum at two different pH levels (3.0 and 7.6) was used to simulate the fluid environment around the joint. Experiments were conducted in two modes of electrochemical control - free-potential and potentiostatic. Electrochemical impedance spectroscopy tests were done before and after the fretting motion to assess changes in corrosion kinetics. In free potential mode, differences were seen in change in potential as a function of displacement amplitude. In general, VDrop (the drop in potential at the onset of fretting), VFretting, (the average potential during fretting), ΔVFretting (the change in potential from the onset of fretting to its termination) and VRecovery (the change in potential from the termination of fretting until stabilization) appeared linear at both pH levels, but showed drastic deviation from linearity at 100μm displacement amplitude. Subsequent EDS analysis revealed a large number of Ti deposits on the CoCrMo pin surfaces. Potentiostatic tests at both pH levels generally showed increasing current with increasing displacement amplitude. Electrochemical

  6. On the geometry of the fuel rod supports concerning a fretting wear failure

    International Nuclear Information System (INIS)

    Kim, Hyung-Kyu; Lee, Young-Ho; Lee, Kang-Hee

    2008-01-01

    Geometrical conditions of spacer grid springs and dimples of a light water reactor fuel assembly are studied in this paper concerning a fuel rod's fretting wear failure. In this framework, the springs/dimples are categorized from the aspects of their orientation with respect to the fuel axis and the contact types. Possible motions on the contacts between the springs/dimples and fuel rods are estimated by conducting a flow-induced vibration test. Features of the wear scar and depth are investigated by independent fretting wear tests carried out with spring and dimple specimens of typical contact geometries. It is also attempted here to apply the contact mechanics theory to a fuel fretting wear analysis such as the prediction of a wear depth profile and its rate, which is influenced by the contact shape of the springs/dimples. It is shown that the theory can be applied to a dimensional control of a coining for the springs/dimples, which is usually carried out in a thin plate fabrication. From the results, the necessary conditions for a spring/dimple geometry for restraining a fretting wear failure are discussed

  7. Design improvement for fretting-wear reduction of HANARO fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yeong Garp; Chae, H. T.; Ryu, J. S.; Kim, H. R

    2000-06-01

    In the course of the visual inspection of the fuel assemblies un-loaded from the reactor core in December 1996, it was observed that many of fuel assemblies had mechanical damages on some components. The major damage was the freting-wear on spacer plates and endplates due to the flow induced vibration of the fuel assembly in the flow tube. Since the reactor is activated and the system modification for complete removal of the driving factors of the vibration of fuel assemblies is practically very difficult, the focus has been on the design change of the fuel assemblies. Consequently, various design changes were proposed to strengthen the wear resistance of the components based on the evaluation of the visual inspection results. The validity of the proposals was verified through the performance tests for the modified components, and the vibration test and endurance test for the fuel assemblies using the single-channel test rig(SCTR) in AECL.The subsequent design changes were additionally proposed based on the visual inspections for the fuel assemblies that had been fabricated according to the first design change and loaded in the core. As the effects of the first design change, the fretting-wear of spacer plates was remarkably reduced and the period until fretting-wear damage was extended by 60% for the first modified 36-rod fuel assembly. It is too early to say the endurance life time for the first modified 18-rod fuel assembly because of insufficient statistical data of only two bundles damaged, but the fretting-wear at the bottom endplate slot was reduced to about 50%. The second modified fuel assemblies, that were not loaded into the core yet, are expected to meet the design requirements for the core residence time due to strengthening the weak parts from the fretting-wear point of view. This report describes design changes and tests for fuel assemblies of HANARO to reduce the fretting-wear, and estimates the effects of design improvement quantitatively compared

  8. Design improvement for fretting-wear reduction of HANARO fuel assembly

    International Nuclear Information System (INIS)

    Cho, Yeong Garp; Chae, H. T.; Ryu, J. S.; Kim, H. R.

    2000-06-01

    In the course of the visual inspection of the fuel assemblies un-loaded from the reactor core in December 1996, it was observed that many of fuel assemblies had mechanical damages on some components. The major damage was the freting-wear on spacer plates and endplates due to the flow induced vibration of the fuel assembly in the flow tube. Since the reactor is activated and the system modification for complete removal of the driving factors of the vibration of fuel assemblies is practically very difficult, the focus has been on the design change of the fuel assemblies. Consequently, various design changes were proposed to strengthen the wear resistance of the components based on the evaluation of the visual inspection results. The validity of the proposals was verified through the performance tests for the modified components, and the vibration test and endurance test for the fuel assemblies using the single-channel test rig(SCTR) in AECL.The subsequent design changes were additionally proposed based on the visual inspections for the fuel assemblies that had been fabricated according to the first design change and loaded in the core. As the effects of the first design change, the fretting-wear of spacer plates was remarkably reduced and the period until fretting-wear damage was extended by 60% for the first modified 36-rod fuel assembly. It is too early to say the endurance life time for the first modified 18-rod fuel assembly because of insufficient statistical data of only two bundles damaged, but the fretting-wear at the bottom endplate slot was reduced to about 50%. The second modified fuel assemblies, that were not loaded into the core yet, are expected to meet the design requirements for the core residence time due to strengthening the weak parts from the fretting-wear point of view. This report describes design changes and tests for fuel assemblies of HANARO to reduce the fretting-wear, and estimates the effects of design improvement quantitatively compared

  9. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. To measure the local deformations on the strands, a novel method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires...... along the length of the monostrand. Information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of a monostrand undergoing flexural deformations is provided. From the series of dynamic fatigue tests, a fretting fatigue spectrum is derived...

  10. Theoretical-experimental analysis of the fretting/impact wear in fuel rods

    International Nuclear Information System (INIS)

    Pecos, Luis F.

    2001-01-01

    Nuclear power plant fuel elements are subjected to flow induced vibrations. A consequence of these vibrations is impact/fretting wear in fuel rods or sliding shoes. Because of the difficulties to assert the mechanism of impact/fretting wear phenomenon it is necessary to use semiempirical formulations in order to predict the wear rate of the components. The results of a series of experiments with Zr-4 specimens are presented in this work. A parameter called 'work-rate' was used to normalize the wear rates and interpret the results in terms of wear coefficient. (author) [es

  11. Improving brightness and photostability of green and red fluorescent proteins for live cell imaging and FRET reporting.

    Science.gov (United States)

    Bajar, Bryce T; Wang, Emily S; Lam, Amy J; Kim, Bongjae B; Jacobs, Conor L; Howe, Elizabeth S; Davidson, Michael W; Lin, Michael Z; Chu, Jun

    2016-02-16

    Many genetically encoded biosensors use Förster resonance energy transfer (FRET) to dynamically report biomolecular activities. While pairs of cyan and yellow fluorescent proteins (FPs) are most commonly used as FRET partner fluorophores, respectively, green and red FPs offer distinct advantages for FRET, such as greater spectral separation, less phototoxicity, and lower autofluorescence. We previously developed the green-red FRET pair Clover and mRuby2, which improves responsiveness in intramolecular FRET reporters with different designs. Here we report the engineering of brighter and more photostable variants, mClover3 and mRuby3. mClover3 improves photostability by 60% and mRuby3 by 200% over the previous generation of fluorophores. Notably, mRuby3 is also 35% brighter than mRuby2, making it both the brightest and most photostable monomeric red FP yet characterized. Furthermore, we developed a standardized methodology for assessing FP performance in mammalian cells as stand-alone markers and as FRET partners. We found that mClover3 or mRuby3 expression in mammalian cells provides the highest fluorescence signals of all jellyfish GFP or coral RFP derivatives, respectively. Finally, using mClover3 and mRuby3, we engineered an improved version of the CaMKIIα reporter Camuiα with a larger response amplitude.

  12. Fluorescence resonance energy transfer (FRET-based subcellular visualization of pathogen-induced host receptor signaling

    Directory of Open Access Journals (Sweden)

    Zimmermann Timo

    2009-11-01

    Full Text Available Abstract Background Bacteria-triggered signaling events in infected host cells are key elements in shaping the host response to pathogens. Within the eukaryotic cell, signaling complexes are spatially organized. However, the investigation of protein-protein interactions triggered by bacterial infection in the cellular context is technically challenging. Here, we provide a methodological approach to exploit fluorescence resonance energy transfer (FRET to visualize pathogen-initiated signaling events in human cells. Results Live-cell microscopy revealed the transient recruitment of the Src family tyrosine kinase Hck upon bacterial engagement of the receptor carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3. In cells expressing a CEACAM3 variant lacking the cytoplasmic domain, the Src homology 2 (SH2 domain of Hck (Hck-SH2 was not recruited, even though bacteria still bound to the receptor. FRET measurements on the basis of whole cell lysates revealed intimate binding between Hck-SH2 (using enhanced yellow fluorescent protein (YPet-Hck-SH2 and the tyrosine-phosphorylated enhanced cyan fluorescent protein-labeled cytoplasmic domain of wild-type CEACAM3 (CEACAM3 WT-CyPet and a flow cytometry-based FRET approach verified this association in intact cells. Using confocal microscopy and acceptor photobleaching, FRET between Hck-SH2 and CEACAM3 was localized to the sites of bacteria-host cell contact. Conclusion These data demonstrate not only the intimate binding of the SH2 domain of Hck to the tyrosine-phosphorylated cytoplasmic domain of CEACAM3 in intact cells, but furthermore, FRET measurements allow the subcellular localization of this process during bacterial infection. FRET-based assays are valuable tools to resolve bacteria-induced protein-protein interactions in the context of the intact host cell.

  13. Application of Influence Function Method to the Fretting Wear Problems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choon Yeol; Tian, Li Si; Bae, Joon Woo; Chai, Young Suck [Yeungnam University, Gyongsan (Korea, Republic of)

    2006-07-01

    Numerical analysis by influence function method (IFM) is demonstrated in this study in order to investigate the fretting wear problems on the secondary side of the steam generator, caused by flow induced vibration. Two-dimensional numerical contact model in terms of Cauchy integral equation is developed. The distributions of normal pressures, shear stresses and displacement fields are derived between two contact bodies which have similar elastic properties. The work rate model is adopted to find the wear amounts between two materials. The results are compared with the solutions by finite element analyses, which show the utilization of the present method to the fretting wear problems.

  14. Application of Influence Function Method to the Fretting Wear Problems

    International Nuclear Information System (INIS)

    Lee, Choon Yeol; Tian, Li Si; Bae, Joon Woo; Chai, Young Suck

    2006-01-01

    Numerical analysis by influence function method (IFM) is demonstrated in this study in order to investigate the fretting wear problems on the secondary side of the steam generator, caused by flow induced vibration. Two-dimensional numerical contact model in terms of Cauchy integral equation is developed. The distributions of normal pressures, shear stresses and displacement fields are derived between two contact bodies which have similar elastic properties. The work rate model is adopted to find the wear amounts between two materials. The results are compared with the solutions by finite element analyses, which show the utilization of the present method to the fretting wear problems

  15. In Situ Probing Intracellular Drug Release from Redox-Responsive Micelles by United FRET and AIE.

    Science.gov (United States)

    Wang, Xuelin; Li, Juanjuan; Yan, Qi; Chen, Yanrui; Fan, Aiping; Wang, Zheng; Zhao, Yanjun

    2018-03-01

    Redox-responsive micelles are versatile nanoplatforms for on-demand drug delivery, but the in situ evaluation of drug release is challenging. Fluorescence resonance energy transfer (FRET) technique shows potential for addressing this, while the aggregation-caused quenching effect limits the assay sensitivity. The aim of the current work is to combine aggregation-induced emission (AIE) probe with FRET to realize drug release assessment from micelles. Tetraphenylethene (TPE) is selected as AIE dye and curcumin (Cur) is chosen as the model drug as well as FRET receptor. The drug is covalently linked to a block copolymer via the disulfide bond linker and TPE is also chemically linked to the polymer via an amide bond; the obtained amphiphilic polymer conjugate self-assembles into micelles with a hydrodynamic size of ≈125 nm. Upon the supplement of glutathione or tris(2-carboxyethyl)phosphine) trigger (10 × 10 -3 m), the drug release induces the fluorescence increase of both TPE and Cur. Accompanied with the FRET decay, absorption enhancement and particle size increase are observed. The same phenomenon is observed in MCF-7 cells. The FRET-AIE approach can be a useful addition to the spectrum of available methods for monitoring drug release from stimuli-responsive nanomedicine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Theoretical Analysis of the Dynamic Properties of a 2-2 Cement-Based Piezoelectric Dual-Layer Stacked Sensor under Impact Load.

    Science.gov (United States)

    Zhang, Taotao; Liao, Yangchao; Zhang, Keping; Chen, Jun

    2017-05-04

    Cement-based piezoelectric materials are widely used due to the fact that compared with common smart materials, they overcome the defects of structure-incompatibility and frequency inconsistency with a concrete structure. However, the present understanding of the mechanical behavior of cement-based piezoelectric smart materials under impact load is still limited. The dynamic characteristics under impact load are of importance, for example, for studying the anti-collision properties of engineering structures and aircraft takeoff-landing safety. Therefore, in this paper, an analytical model was proposed to investigate the dynamic properties of a 2-2 cement-based piezoelectric dual-layer stacked sensor under impact load based on the piezoelectric effect. Theoretical solutions are obtained by utilizing the variable separation and Duhamel integral method. To simulate the impact load and verify the theory, three types of loads, including atransient step load, isosceles triangle load and haversine wave load, are considered and the comparisons between the theoretical results, Li's results and numerical results are presented by using the control variate method and good agreement is found. Furthermore, the influences of several parameters were discussed and other conclusions about this sensor are also given. This should prove very helpful for the design and optimization of the 2-2 cement-based piezoelectric dual-layer stacked sensor in engineering.

  17. Advanced KSNP fuel, plus7 : grid-to-rod fretting wear resistance of the plus7 spacer grids

    International Nuclear Information System (INIS)

    Kim, Kyu Tae; Kim, Yong Hwan; Jang, Young Ki; Choi, Joon Hyung

    2003-01-01

    Vibration-induced grid-to-rod fretting wear initiates at a certain critical gap correlated with a critical work rate. A critical gap between grid and rod forms due to in-reactor performance of fuel, thermal relaxation of grid spring and irradiation growth of grid strap, etc. A critical work rate may be generated by three vibration mechanisms proposed in this paper. Three vibration mechanisms have been derived with various fretting wear experience in commercial reactors as well as various out-of-pile hydraulic test results. The first active vibration mechanism is high turbulence-induced excessive fuel rod vibration with the combination of excessive grid-to-rod gap. The second active vibration mechanism is self-excited fuel assembly vibration in a low frequency range caused by hydraulically unbalanced mixing vanes of the spacer grid assembly. The third active vibration mechanism is self-excited spacer grid strap vibration in quite a high frequency range caused by some spacer grid designs. In this study, each vibration mechanism on the grid-to-rod fretting wear damage is discussed. On the other hand, the effects of various grid designs on the fretting wear damage in the commercial reactors are predicted using the long-term fretting wear test results. It is found that the larger grid-to-rod initial contact area generates the less fretting wear damage. Consequently the conformal spring of PLUS7 is superior to typical convex shaped spring with regard to fretting wear resistance since the former generates relatively larger contact area than the latter

  18. Dual permeability FEM models for distributed fiber optic sensors development

    Science.gov (United States)

    Aguilar-López, Juan Pablo; Bogaard, Thom

    2017-04-01

    Fiber optic cables are commonly known for being robust and reliable mediums for transferring information at the speed of light in glass. Billions of kilometers of cable have been installed around the world for internet connection and real time information sharing. Yet, fiber optic cable is not only a mean for information transfer but also a way to sense and measure physical properties of the medium in which is installed. For dike monitoring, it has been used in the past for detecting inner core and foundation temperature changes which allow to estimate water infiltration during high water events. The DOMINO research project, aims to develop a fiber optic based dike monitoring system which allows to directly sense and measure any pore pressure change inside the dike structure. For this purpose, questions like which location, how many sensors, which measuring frequency and which accuracy are required for the sensor development. All these questions may be initially answered with a finite element model which allows to estimate the effects of pore pressure change in different locations along the cross section while having a time dependent estimation of a stability factor. The sensor aims to monitor two main failure mechanisms at the same time; The piping erosion failure mechanism and the macro-stability failure mechanism. Both mechanisms are going to be modeled and assessed in detail with a finite element based dual permeability Darcy-Richards numerical solution. In that manner, it is possible to assess different sensing configurations with different loading scenarios (e.g. High water levels, rainfall events and initial soil moisture and permeability conditions). The results obtained for the different configurations are later evaluated based on an entropy based performance evaluation. The added value of this kind of modelling approach for the sensor development is that it allows to simultaneously model the piping erosion and macro-stability failure mechanisms in a time

  19. A Novel Water-soluble Ratiometric Fluorescent Probe Based on FRET for Sensing Lysosomal pH.

    Science.gov (United States)

    Song, Guang-Jie; Bai, Su-Yun; Luo, Jing; Cao, Xiao-Qun; Zhao, Bao-Xiang

    2016-11-01

    A new ratiometric fluorescent probe based on Förster resonance energy transfer (FRET) for sensing lysosomal pH has been developed. The probe (RMPM) was composed of imidazo[1,5-α]pyridine quaternary ammonium salt fluorophore as the FRET donor and the rhodamine moiety as the FRET acceptor. It's the first time to report that imidazo[1,5-α]pyridine quaternary ammonium salt acts as the FRET donor. The ratio of fluorescence intensity of the probe at two wavelengths (I 424 /I 581 ) changed significantly and responded linearly toward minor pH changes in the range of 5.4-6.6. It should be noted that it's rare to report that a ratiometric pH probe could detect so weak acidic pH with pKa = 6.31. In addition, probe RMPM exhibited excellent water-solubility, fast-response, all-right selectivity and brilliant reversibility. Moreover, RMPM has been successfully applied to sensing lysosomal pH in HeLa cells and has low cytotoxicity.

  20. The role of FRET in solar concentrator efficiency and color tunability

    Energy Technology Data Exchange (ETDEWEB)

    Balaban, Benjamin, E-mail: bbalaban@ucsc.edu; Doshay, Sage; Osborn, Melissa; Rodriguez, Yvonne; Carter, Sue A., E-mail: sacarter@ucsc.edu

    2014-02-15

    We demonstrate concentration-dependent Förster-type energy transfer in a luminescent solar concentrator (LSC) material containing two high quantum yield laser dyes in a PMMA matrix. FRET heterotransfer is shown to be approximately 50% efficient in the regime of 2×10{sup −3}molal acceptor dye by weight in the host polymer. The two dyes used have been well studied for solar concentrator applications: BASF's Lumogen Red 305, and Exciton Chemical Company's DCM both demonstrate desirable stability, quantum yield, and complementary absorption spectra. We demonstrate how multiple-dye LSC devices employing FRET increase the absorption of air mass 1.5 solar irradiance without affecting the self-absorption properties of the film. Color tunability may be achieved through the addition of additional absorbers while minimizing the impact on waveguide efficiency. -- Highlights: • Förster Resonance Energy Transfer is demonstrated in a two-dye luminescent solar concentrator. • Donor-acceptor pair distance is related to the dye concentration in PMMA. • FRET's benefit to waveguide transport losses and color tunability is discussed.

  1. FRET analysis of CP12 structural interplay by GAPDH and PRK.

    Science.gov (United States)

    Moparthi, Satish Babu; Thieulin-Pardo, Gabriel; de Torres, Juan; Ghenuche, Petru; Gontero, Brigitte; Wenger, Jérôme

    2015-03-13

    CP12 is an intrinsically disordered protein playing a key role in the regulation of the Benson-Calvin cycle. Due to the high intrinsic flexibility of CP12, it is essential to consider its structural modulation induced upon binding to the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK) enzymes. Here, we report for the first time detailed structural modulation about the wild-type CP12 and its site-specific N-terminal and C-terminal disulfide bridge mutants upon interaction with GAPDH and PRK by Förster resonance energy transfer (FRET). Our results indicate an increase in CP12 compactness when the complex is formed with GAPDH or PRK. In addition, the distributions in FRET histograms show the elasticity and conformational flexibility of CP12 in all supra molecular complexes. Contrarily to previous beliefs, our FRET results importantly reveal that both N-terminal and C-terminal site-specific CP12 mutants are able to form the monomeric (GAPDH-CP12-PRK) complex. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Double-labeled donor probe can enhance the signal of fluorescence resonance energy transfer (FRET) in detection of nucleic acid hybridization

    Science.gov (United States)

    Okamura, Yukio; Kondo, Satoshi; Sase, Ichiro; Suga, Takayuki; Mise, Kazuyuki; Furusawa, Iwao; Kawakami, Shigeki; Watanabe, Yuichiro

    2000-01-01

    A set of fluorescently-labeled DNA probes that hybridize with the target RNA and produce fluorescence resonance energy transfer (FRET) signals can be utilized for the detection of specific RNA. We have developed probe sets to detect and discriminate single-strand RNA molecules of plant viral genome, and sought a method to improve the FRET signals to handle in vivo applications. Consequently, we found that a double-labeled donor probe labeled with Bodipy dye yielded a remarkable increase in fluorescence intensity compared to a single-labeled donor probe used in an ordinary FRET. This double-labeled donor system can be easily applied to improve various FRET probes since the dependence upon sequence and label position in enhancement is not as strict. Furthermore this method could be applied to other nucleic acid substances, such as oligo RNA and phosphorothioate oligonucleotides (S-oligos) to enhance FRET signal. Although the double-labeled donor probes labeled with a variety of fluorophores had unexpected properties (strange UV-visible absorption spectra, decrease of intensity and decay of donor fluorescence) compared with single-labeled ones, they had no relation to FRET enhancement. This signal amplification mechanism cannot be explained simply based on our current results and knowledge of FRET. Yet it is possible to utilize this double-labeled donor system in various applications of FRET as a simple signal-enhancement method. PMID:11121494

  3. FRET enhancement close to gold nanoparticles positioned in DNA origami constructs.

    Science.gov (United States)

    Aissaoui, Nesrine; Moth-Poulsen, Kasper; Käll, Mikael; Johansson, Peter; Wilhelmsson, L Marcus; Albinsson, Bo

    2017-01-05

    Here we investigate the energy transfer rates of a Förster resonance energy transfer (FRET) pair positioned in close proximity to a 5 nm gold nanoparticle (AuNP) on a DNA origami construct. We study the distance dependence of the FRET rate by varying the location of the donor molecule, D, relative to the AuNP while maintaining a fixed location of the acceptor molecule, A. The presence of the AuNP induces an alteration in the spontaneous emission of the donor (including radiative and non-radiative rates) which is strongly dependent on the distance between the donor and AuNP surface. Simultaneously, the energy transfer rates are enhanced at shorter D-A (and D-AuNP) distances. Overall, in addition to the direct influence of the acceptor and AuNP on the donor decay there is also a significant increase in decay rate not explained by the sum of the two interactions. This leads to enhanced energy transfer between donor and acceptor in the presence of a 5 nm AuNP. We also demonstrate that the transfer rate in the three "particle" geometry (D + A + AuNP) depends approximately linearly on the transfer rate in the donor-AuNP system, suggesting the possibility to control FRET process with electric field induced by 5 nm AuNPs close to the donor fluorophore. It is concluded that DNA origami is a very versatile platform for studying interactions between molecules and plasmonic nanoparticles in general and FRET enhancement in particular.

  4. Polyfluorophore Excimers and Exciplexes as FRET Donors in DNA

    Science.gov (United States)

    Teo, Yin Nah; Kool, Eric T.

    2009-01-01

    We describe studies aimed at testing whether oligomeric exciplex- and excimer fluorophores conjugated to DNA have the potential to act as donors for energy transfer by the Förster mechanism. Oligodeoxyfluorosides (ODFs) are composed of stacked, electronically interacting fluorophores replacing the bases on a DNA scaffold. The monomer chromophores in the twenty tetramer-length ODFs studied here include pyrene (Y), benzopyrene (B), perylene (E), dimethylaminostilbene (D), and a nonfluorescent spacer (S); these are conjugated in varied combinations at the 3’ end of a 14mer DNA probe sequence. In the absence of an acceptor chromophore, many of the ODF-DNAs show broad, unstructured long-wavelength emission peaks characteristic of excimer and exciplex excited states, similar to what has been observed for unconjugated ODFs. Although such delocalized excited states have been widely studied, we know of no prior report of their use in FRET. We tested the ability of the twenty ODFs to donate energy to Cy5 and TAMRA dyes conjugated to a complementary strand of DNA, with these acceptors oriented either at the near or far end of the ODF-conjugated probes. Results showed that a number of the ODF fluorophores exhibited relatively efficient energy transfer characteristic of the Förster mechanism, as judged by drops in donor emission quantum yield and fluorescence lifetime, accompanied by increases in intensity of acceptor emission bands. Excimer/exciplex bands in the donors were selectively quenched while shorter-wavelength monomer emission stayed relatively constant, consistent with the notion that the delocalized excited states, rather than individual fluorophores, are the donors. Interestingly, only specific sequences of ODFs were able to act as donors, while others did not, even though their emission wavelengths were similar. The new FRET donors possess large Stokes shifts, which can be beneficial for multiple applications. In addition, all ODFs can be excited at a single

  5. Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions.

    Science.gov (United States)

    Götz, Markus; Wortmann, Philipp; Schmid, Sonja; Hugel, Thorsten

    2018-01-30

    Single-molecule Förster resonance energy transfer (smFRET) has become a widely used biophysical technique to study the dynamics of biomolecules. For many molecular machines in a cell proteins have to act together with interaction partners in a functional cycle to fulfill their task. The extension of two-color to multi-color smFRET makes it possible to simultaneously probe more than one interaction or conformational change. This not only adds a new dimension to smFRET experiments but it also offers the unique possibility to directly study the sequence of events and to detect correlated interactions when using an immobilized sample and a total internal reflection fluorescence microscope (TIRFM). Therefore, multi-color smFRET is a versatile tool for studying biomolecular complexes in a quantitative manner and in a previously unachievable detail. Here, we demonstrate how to overcome the special challenges of multi-color smFRET experiments on proteins. We present detailed protocols for obtaining the data and for extracting kinetic information. This includes trace selection criteria, state separation, and the recovery of state trajectories from the noisy data using a 3D ensemble Hidden Markov Model (HMM). Compared to other methods, the kinetic information is not recovered from dwell time histograms but directly from the HMM. The maximum likelihood framework allows us to critically evaluate the kinetic model and to provide meaningful uncertainties for the rates. By applying our method to the heat shock protein 90 (Hsp90), we are able to disentangle the nucleotide binding and the global conformational changes of the protein. This allows us to directly observe the cooperativity between the two nucleotide binding pockets of the Hsp90 dimer.

  6. Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems

    DEFF Research Database (Denmark)

    Börjesson, Karl; Preus, Søren; El-Sagheer, Afaf

    2009-01-01

    We present the first nucleobase analog fluorescence resonance energy transfer (FRET)-pair. The pair consists of tCO, 1,3-diaza-2-oxophenoxazine, as an energy donor and the newly developed tC(nitro), 7-nitro-1,3-diaza-2-oxophenothiazine, as an energy acceptor. The FRET-pair successfully monitors d...

  7. Burst pressure and leak rate from fretted SG tubes

    International Nuclear Information System (INIS)

    Hwang, Seong Sik; Jung, Man Kyo; Kim, Hong Pyo; Kim, Joung Soo

    2005-01-01

    Steam generator(SG) tubes of a pressurized water reactor(PWR) have suffered from various types of corrosion, such as pitting, wastage and stress corrosion cracking (SCC) on both the primary and secondary side. Recently, fretting/wear degradation at the tube support region has been reported in some Korean nuclear power plants. In order to prevent the primary coolant from leaking to the secondary side, the tubes are repaired by a sleeving or plugging. It is important to establish the repair criteria to assure a reactor integrity and yet maintain the plugging ratio within the limits needed for an efficient operation. The objective of the burst test is to obtain a relationship between the burst/leak rate and the shape of the fretted flaws machined with an electro discharge machining (EDM)

  8. Improved sensing characteristics of dual-gate transistor sensor using silicon nanowire arrays defined by nanoimprint lithography

    Science.gov (United States)

    Lim, Cheol-Min; Lee, In-Kyu; Lee, Ki Joong; Oh, Young Kyoung; Shin, Yong-Beom; Cho, Won-Ju

    2017-12-01

    This work describes the construction of a sensitive, stable, and label-free sensor based on a dual-gate field-effect transistor (DG FET), in which uniformly distributed and size-controlled silicon nanowire (SiNW) arrays by nanoimprint lithography act as conductor channels. Compared to previous DG FETs with a planar-type silicon channel layer, the constructed SiNW DG FETs exhibited superior electrical properties including a higher capacitive-coupling ratio of 18.0 and a lower off-state leakage current under high-temperature stress. In addition, while the conventional planar single-gate (SG) FET- and planar DG FET-based pH sensors showed the sensitivities of 56.7 mV/pH and 439.3 mV/pH, respectively, the SiNW DG FET-based pH sensors showed not only a higher sensitivity of 984.1 mV/pH, but also a lower drift rate of 0.8% for pH-sensitivity. This demonstrates that the SiNW DG FETs simultaneously achieve high sensitivity and stability, with significant potential for future biosensing applications.

  9. Extraction of information on macromolecular interactions from fluorescence micro-spectroscopy measurements in the presence and absence of FRET

    Science.gov (United States)

    Raicu, Valerică

    2018-06-01

    Investigations of static or dynamic interactions between proteins or other biological macromolecules in living cells often rely on the use of fluorescent tags with two different colors in conjunction with adequate theoretical descriptions of Förster Resonance Energy Transfer (FRET) and molecular-level micro-spectroscopic technology. One such method based on these general principles is FRET spectrometry, which allows determination of the quaternary structure of biomolecules from cell-level images of the distributions, or spectra of occurrence frequency of FRET efficiencies. Subsequent refinements allowed combining FRET frequency spectra with molecular concentration information, thereby providing the proportion of molecular complexes with various quaternary structures as well as their binding/dissociation energies. In this paper, we build on the mathematical principles underlying FRET spectrometry to propose two new spectrometric methods, which have distinct advantages compared to other methods. One of these methods relies on statistical analysis of color mixing in subpopulations of fluorescently tagged molecules to probe molecular association stoichiometry, while the other exploits the color shift induced by FRET to also derive geometric information in addition to stoichiometry. The appeal of the first method stems from its sheer simplicity, while the strength of the second consists in its ability to provide structural information.

  10. Fretting wear simulation of press-fitted shaft with finite element analysis and influence function method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Hyong; Kwon, Seok Jin [Korea Railroad Research Institute, Uiwang (Korea, Republic of); Choi, Jae Boong; Kim, Young Jin [Sungkyunkwan University, Suwon (Korea, Republic of)

    2008-01-15

    In this paper the fretting wear of press-fitted specimens subjected to a cyclic bending load was simulated using finite element analysis and numerical method. The amount of microslip and contact variable at press-fitted and bending load condition in a press-fitted shaft was analysed by applying finite element method. With the finite element analysis result, a numerical approach was applied to predict fretting wear based on modified Archard's equation and updating the change of contact pressure caused by local wear with influence function method. The predicted wear profiles of press-fitted specimens at the contact edge wear compared with the experimental results obtained by rotating bending fatigue tests. It is shown that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact variables are redistributed. The work establishes a basis for numerical simulation of fretting wear on press fits.

  11. Fretting wear simulation of press-fitted shaft with finite element analysis and influence function method

    International Nuclear Information System (INIS)

    Lee, Dong Hyong; Kwon, Seok Jin; Choi, Jae Boong; Kim, Young Jin

    2008-01-01

    In this paper the fretting wear of press-fitted specimens subjected to a cyclic bending load was simulated using finite element analysis and numerical method. The amount of microslip and contact variable at press-fitted and bending load condition in a press-fitted shaft was analysed by applying finite element method. With the finite element analysis result, a numerical approach was applied to predict fretting wear based on modified Archard's equation and updating the change of contact pressure caused by local wear with influence function method. The predicted wear profiles of press-fitted specimens at the contact edge wear compared with the experimental results obtained by rotating bending fatigue tests. It is shown that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact variables are redistributed. The work establishes a basis for numerical simulation of fretting wear on press fits

  12. Theoretical Analysis of the Dynamic Properties of a 2-2 Cement-Based Piezoelectric Dual-Layer Stacked Sensor under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2017-05-01

    Full Text Available Cement-based piezoelectric materials are widely used due to the fact that compared with common smart materials, they overcome the defects of structure-incompatibility and frequency inconsistency with a concrete structure. However, the present understanding of the mechanical behavior of cement-based piezoelectric smart materials under impact load is still limited. The dynamic characteristics under impact load are of importance, for example, for studying the anti-collision properties of engineering structures and aircraft takeoff-landing safety. Therefore, in this paper, an analytical model was proposed to investigate the dynamic properties of a 2-2 cement-based piezoelectric dual-layer stacked sensor under impact load based on the piezoelectric effect. Theoretical solutions are obtained by utilizing the variable separation and Duhamel integral method. To simulate the impact load and verify the theory, three types of loads, including atransient step load, isosceles triangle load and haversine wave load, are considered and the comparisons between the theoretical results, Li’s results and numerical results are presented by using the control variate method and good agreement is found. Furthermore, the influences of several parameters were discussed and other conclusions about this sensor are also given. This should prove very helpful for the design and optimization of the 2-2 cement-based piezoelectric dual-layer stacked sensor in engineering.

  13. Simulation of vibration modes of the fuel rod damaged due to the grid-to-rod fretting wear

    International Nuclear Information System (INIS)

    Kim, Kyu Tae; Kim, Kyeong Koo; Jang, Young Ki; Lee, Kyou Seok

    1997-01-01

    The flow-induced fuel fretting wear observed in some PWRs mainly proceeds in the grid-to-rod contact positions. The grid-to-rod fretting wear in the PWR fuel assembly depends on grid-to-rod gap size, its axial profile and flow-induced vibration. This paper describes the GRIDFORCE program which generates the axially dependent grid-to-rod gap size as a function of burnup. The axially dependent grid-to-rod gap profiles are employed to predict the fuel rod vibration mode shapes by the ANSYS code. With the help of the Paidousis empirical formula, this paper also calculates the fuel rod vibration amplitudes under various supporting conditions, which indicates that the increase of the number of unsupported mid-grids will increase the fuel rod vibration amplitude. On the other hand, the comparison of the predicted vibration mode shapes and the observed mid-grid fretting wear pattern indicates that the 1st and 6th vibration mode shapes under the supporting inactive condition at the mid-grids can simulate the observed mid-grid fretting wear profile. This paper also proposes design guidelines against the grid-to-rod fretting wear. (author). 3 refs., 8 figs

  14. Fretting Corrosion Behavior of Experimental Ti-20Cr Compared to Titanium.

    Science.gov (United States)

    Sawada, Tomofumi; Schille, Christine; Almadani, Atif; Geis-Gerstorfer, Jürgen

    2017-02-17

    Experimental cast titanium alloys containing 20 mass% chromium (Ti-20Cr) show preferable mechanical properties and a good corrosion resistance. This study evaluated the fretting corrosion behavior of Ti-20Cr. Ti-20Cr ( n = 4) and commercially pure titanium (CP-Ti, n = 6) disk specimens were used. The fretting corrosion test was performed by electrochemical corrosion at 0.3 V in 0.9% saline solution and mechanical damage using 10 scratching cycles with three different scratching speeds (10-40 mm/s) at 10 N. After testing, the activation peak, repassivation time and surface morphology of each specimen were analyzed. The differences between the results were tested by parametric tests (α = 0.05). The average activation peaks were significantly higher in CP-Ti than in Ti-20Cr ( p Ti. Slight differences in the repassivation time were observed between the materials at every scratching speed; faster scratching speeds showed shorter repassivation times in both materials ( p Ti showed severe damage and significantly higher wear depth than Ti-20Cr ( p < 0.05). In conclusion, adding chromium to titanium reduced surface damage and improved the fretting corrosion resistance.

  15. Fluorescent protein pair emit intracellular FRET signal suitable for FACS screening

    International Nuclear Information System (INIS)

    Johansson, Daniel X.; Brismar, Hjalmar; Persson, Mats A.A.

    2007-01-01

    The fluorescent proteins ECFP and HcRed were shown to give an easily resolved FRET-signal when expressed as a fusion inside mammalian cells. HeLa-tat cells expressing ECFP, pHcRed, or the fusion protein pHcRed-ECFP were analyzed by flow cytometry after excitation of ECFP. Cells expressing HcRed-ECFP, or ECFP and HcRed, were mixed and FACS-sorted for FRET positive cells: HcRed-ECFP cells were greatly enriched (72 times). Next, cloned human antibodies were fused with ECFP and expressed anchored to the ER membrane. Their cognate antigens (HIV-1 gp120 or gp41) were fused to HcRed and co-expressed in the ER. An increase of 13.5 ± 1.5% (mean ± SEM) and 8.0 ± 0.7% in ECFP fluorescence for the specific antibodies reacting with gp120 or gp41, respectively, was noted after photobleaching. A positive control (HcRed-ECFP) gave a 14.8 ± 2.6% increase. Surprisingly, the unspecific antibody (anti-TT) showed 12.1 ± 1.1% increase, possibly because overexpression in the limited ER compartment gave false FRET signals

  16. Determination of a Wear Initiation Cycle by using a Contact Resistance Measurement in Nuclear Fuel Fretting

    International Nuclear Information System (INIS)

    Lee, Young Ho; Kim, Hyung Kyu

    2008-01-01

    In nuclear fuel fretting, the improving of the contact condition with a modified spring shape is a useful method for increasing the wear resistance of the nuclear fuel rod. This is because the fretting wear resistance between the fuel rod and grid spring is mainly affected by the grid spring shape rather than the environment, the contact modes, etc. In addition, the wear resistance is affected by the wear debris behavior between contact surfaces. So, it is expected that the wear initiation of each spring shape should be determined in order to evaluate a wear resistance. However, it is almost impossible to measure the wear behavior in contact surfaces on a real time basis because the contact surfaces are always hidden. Besides, the results of the worn surface observation after the fretting wear tests are restricted to archive the information on the wear debris behavior and the formation mechanism of the wear scar. In order to evaluate the wear behavior during the fretting wear tests, it is proposed that the contact resistance measurement is a useful method for examining the wear initiation cycle and modes. Generally, fretting wear damages are rapidly progressed by a localized plastic deformation between the contact surfaces, crack initiation and fracture of the deformed surface with a strain hardening difference between a surface and a subsurface and finally a detachment of wear debris. After this, wear debris is easily oxidized by frictional heat, test environment, etc. At this time, a small amount of electric current applied between the contact surfaces will be influenced by the wear debris, which could be an obstacle to an electric current flow. So, it is possible to archive the information on the wear behavior by measuring the contact resistance. In order to determine the wear initiation cycle during the fretting wear tests, in this study, fretting wear tests have been performed by applying a constant electric current in room temperature air

  17. Fretting wear damage of steam generator tubes and its prediction modeling

    International Nuclear Information System (INIS)

    Che Honglong; Lei Mingkai

    2013-01-01

    The steam generator is the key equipment used for the energy transition in nuclear power plant. Since the high-temperature and high-pressure fluid flows with high speed, the steam generator tubes will be excited and vibrate, leading to the tremendous fretting wear problem on the tubes, sometimes even leading to tube cracking. This paper introduces typical fretting wear cases, the result of corresponding simulation wear experiment and damage mechanism which combining mechanical wear and erosion-corrosion. Work rate model could give a reasonable life prediction about the steam generator tube, and this predictive model has been used in nuclear power plant safety assessment. (authors)

  18. Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties

    Directory of Open Access Journals (Sweden)

    Niko Hildebrandt

    2011-10-01

    Full Text Available Förster resonance energy transfer (FRET from luminescent terbium complexes (LTC as donors to semiconductor quantum dots (QDs as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma.

  19. Studying DNA looping by single-molecule FRET.

    Science.gov (United States)

    Le, Tung T; Kim, Harold D

    2014-06-28

    Bending of double-stranded DNA (dsDNA) is associated with many important biological processes such as DNA-protein recognition and DNA packaging into nucleosomes. Thermodynamics of dsDNA bending has been studied by a method called cyclization which relies on DNA ligase to covalently join short sticky ends of a dsDNA. However, ligation efficiency can be affected by many factors that are not related to dsDNA looping such as the DNA structure surrounding the joined sticky ends, and ligase can also affect the apparent looping rate through mechanisms such as nonspecific binding. Here, we show how to measure dsDNA looping kinetics without ligase by detecting transient DNA loop formation by FRET (Fluorescence Resonance Energy Transfer). dsDNA molecules are constructed using a simple PCR-based protocol with a FRET pair and a biotin linker. The looping probability density known as the J factor is extracted from the looping rate and the annealing rate between two disconnected sticky ends. By testing two dsDNAs with different intrinsic curvatures, we show that the J factor is sensitive to the intrinsic shape of the dsDNA.

  20. Simple estimation of Förster Resonance Energy Transfer (FRET) orientation factor distribution in membranes.

    Science.gov (United States)

    Loura, Luís M S

    2012-11-19

    Because of its acute sensitivity to distance in the nanometer scale, Förster resonance energy transfer (FRET) has found a large variety of applications in many fields of chemistry, physics, and biology. One important issue regarding the correct usage of FRET is its dependence on the donor-acceptor relative orientation, expressed as the orientation factor k(2). Different donor/acceptor conformations can lead to k(2) values in the 0 ≤ k(2) ≤ 4 range. Because the characteristic distance for FRET, R(0), is proportional to (k(2))1/6, uncertainties in the orientation factor are reflected in the quality of information that can be retrieved from a FRET experiment. In most cases, the average value of k(2) corresponding to the dynamic isotropic limit ( = 2/3) is used for computation of R(0) and hence donor-acceptor distances and acceptor concentrations. However, this can lead to significant error in unfavorable cases. This issue is more critical in membrane systems, because of their intrinsically anisotropic nature and their reduced fluidity in comparison to most common solvents. Here, a simple numerical simulation method for estimation of the probability density function of k(2) for membrane-embedded donor and acceptor fluorophores in the dynamic regime is presented. In the simplest form, the proposed procedure uses as input the most probable orientations of the donor and acceptor transition dipoles, obtained by experimental (including linear dichroism) or theoretical (such as molecular dynamics simulation) techniques. Optionally, information about the widths of the donor and/or acceptor angular distributions may be incorporated. The methodology is illustrated for special limiting cases and common membrane FRET pairs.

  1. A dark green fluorescent protein as an acceptor for measurement of Förster resonance energy transfer.

    Science.gov (United States)

    Murakoshi, Hideji; Shibata, Akihiro C E; Nakahata, Yoshihisa; Nabekura, Junichi

    2015-10-15

    Measurement of Förster resonance energy transfer by fluorescence lifetime imaging microscopy (FLIM-FRET) is a powerful method for visualization of intracellular signaling activities such as protein-protein interactions and conformational changes of proteins. Here, we developed a dark green fluorescent protein (ShadowG) that can serve as an acceptor for FLIM-FRET. ShadowG is spectrally similar to monomeric enhanced green fluorescent protein (mEGFP) and has a 120-fold smaller quantum yield. When FRET from mEGFP to ShadowG was measured using an mEGFP-ShadowG tandem construct with 2-photon FLIM-FRET, we observed a strong FRET signal with low cell-to-cell variability. Furthermore, ShadowG was applied to a single-molecule FRET sensor to monitor a conformational change of CaMKII and of the light oxygen voltage (LOV) domain in HeLa cells. These sensors showed reduced cell-to-cell variability of both the basal fluorescence lifetime and response signal. In contrast to mCherry- or dark-YFP-based sensors, our sensor allowed for precise measurement of individual cell responses. When ShadowG was applied to a separate-type Ras FRET sensor, it showed a greater response signal than did the mCherry-based sensor. Furthermore, Ras activation and translocation of its effector ERK2 into the nucleus could be observed simultaneously. Thus, ShadowG is a promising FLIM-FRET acceptor.

  2. Graphene and graphene-like two-denominational materials based fluorescence resonance energy transfer (FRET) assays for biological applications.

    Science.gov (United States)

    Tian, Feng; Lyu, Jing; Shi, Jingyu; Yang, Mo

    2017-03-15

    In the past decades, Förster resonance energy transfer (FRET) has been applied in many biological applications to reveal the biological information at the nanoscale. Recently, graphene and graphene-like two-dimensional (2D) nanomaterials started to be used in FRET assays as donors or acceptors including graphene oxide (GO), graphene quantum dot (GQD), graphitic-carbon nitride nanosheets (g-C 3 N 4 ) and transition metal dichalcogenides (e.g. MoS 2 , MnO 2, and WS 2 ). Due to the remarkable properties such as large surface to volume ratio, tunable energy band, photoluminescence and excellent biocompatibility, these 2D nanomaterials based FRET assays have shown great potential in various biological applications. This review summarizes the recent development of graphene and graphene-like 2D nanomaterials based FRET assays in applications of biosensing, bioimaging, and drug delivery monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Temperature dependent dual hydrogen sensor response of Pd nanoparticle decorated Al doped ZnO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, D.; Barman, P. B.; Hazra, S. K., E-mail: surajithazra@yahoo.co.in [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh-173234 (India); Dutta, D. [IC Design and Fabrication Centre, Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); Kumar, M.; Som, T. [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

    2015-10-28

    Sputter deposited Al doped ZnO (AZO) thin films exhibit a dual hydrogen sensing response in the temperature range 40 °C–150 °C after surface modifications with palladium nanoparticles. The unmodified AZO films showed no response in hydrogen in the temperature range 40 °C–150 °C. The operational temperature windows on the low and high temperature sides have been estimated by isolating the semiconductor-to-metal transition temperature zone of the sensor device. The gas response pattern was modeled by considering various adsorption isotherms, which revealed the dominance of heterogeneous adsorption characteristics. The Arrhenius adsorption barrier showed dual variation with change in hydrogen gas concentration on either side of the semiconductor-to-metal transition. A detailed analysis of the hydrogen gas response pattern by considering the changes in nano palladium due to hydrogen adsorption, and semiconductor-to-metal transition of nanocrystalline Al doped ZnO layer due to temperature, along with material characterization studies by glancing incidence X-ray diffraction, atomic force microscopy, and transmission electron microscopy, are presented.

  4. A Quantitative Theoretical Framework For Protein-Induced Fluorescence Enhancement-Förster-Type Resonance Energy Transfer (PIFE-FRET).

    Science.gov (United States)

    Lerner, Eitan; Ploetz, Evelyn; Hohlbein, Johannes; Cordes, Thorben; Weiss, Shimon

    2016-07-07

    Single-molecule, protein-induced fluorescence enhancement (PIFE) serves as a molecular ruler at molecular distances inaccessible to other spectroscopic rulers such as Förster-type resonance energy transfer (FRET) or photoinduced electron transfer. In order to provide two simultaneous measurements of two distances on different molecular length scales for the analysis of macromolecular complexes, we and others recently combined measurements of PIFE and FRET (PIFE-FRET) on the single molecule level. PIFE relies on steric hindrance of the fluorophore Cy3, which is covalently attached to a biomolecule of interest, to rotate out of an excited-state trans isomer to the cis isomer through a 90° intermediate. In this work, we provide a theoretical framework that accounts for relevant photophysical and kinetic parameters of PIFE-FRET, show how this framework allows the extraction of the fold-decrease in isomerization mobility from experimental data, and show how these results provide information on changes in the accessible volume of Cy3. The utility of this model is then demonstrated for experimental results on PIFE-FRET measurement of different protein-DNA interactions. The proposed model and extracted parameters could serve as a benchmark to allow quantitative comparison of PIFE effects in different biological systems.

  5. FLIM-FRET image analysis of tryptophan in prostate cancer cells

    Science.gov (United States)

    Periasamy, Ammasi; Alam, Shagufta R.; Svindrych, Zdenek; Wallrabe, Horst

    2017-07-01

    A region of interest (ROI) based quantitative FLIM-FRET image analysis is developed to quantitate the autofluorescence signals of the essential amino acid tryptophan as a biomarker to investigate the metabolism in prostate cancer cells.

  6. Design and implementation of a Sun tracker with a dual-axis single motor for an optical sensor-based photovoltaic system.

    Science.gov (United States)

    Wang, Jing-Min; Lu, Chia-Liang

    2013-03-06

    The dual threats of energy depletion and global warming place the development of methods for harnessing renewable energy resources at the center of public interest. Solar energy is one of the most promising renewable energy resources. Sun trackers can substantially improve the electricity production of a photovoltaic (PV) system. This paper proposes a novel design of a dual-axis solar tracking PV system which utilizes the feedback control theory along with a four-quadrant light dependent resistor (LDR) sensor and simple electronic circuits to provide robust system performance. The proposed system uses a unique dual-axis AC motor and a stand-alone PV inverter to accomplish solar tracking. The control implementation is a technical innovation that is a simple and effective design. In addition, a scaled-down laboratory prototype is constructed to verify the feasibility of the scheme. The effectiveness of the Sun tracker is confirmed experimentally. To conclude, the results of this study may serve as valuable references for future solar energy applications.

  7. Design and Implementation of a Sun Tracker with a Dual-Axis Single Motor for an Optical Sensor-Based Photovoltaic System

    Directory of Open Access Journals (Sweden)

    Chia-Liang Lu

    2013-03-01

    Full Text Available The dual threats of energy depletion and global warming place the development of methods for harnessing renewable energy resources at the center of public interest. Solar energy is one of the most promising renewable energy resources. Sun trackers can substantially improve the electricity production of a photovoltaic (PV system. This paper proposes a novel design of a dual-axis solar tracking PV system which utilizes the feedback control theory along with a four-quadrant light dependent resistor (LDR sensor and simple electronic circuits to provide robust system performance. The proposed system uses a unique dual-axis AC motor and a stand-alone PV inverter to accomplish solar tracking. The control implementation is a technical innovation that is a simple and effective design. In addition, a scaled-down laboratory prototype is constructed to verify the feasibility of the scheme. The effectiveness of the Sun tracker is confirmed experimentally. To conclude, the results of this study may serve as valuable references for future solar energy applications.

  8. Design and Implementation of a Sun Tracker with a Dual-Axis Single Motor for an Optical Sensor-Based Photovoltaic System

    Science.gov (United States)

    Wang, Jing-Min; Lu, Chia-Liang

    2013-01-01

    The dual threats of energy depletion and global warming place the development of methods for harnessing renewable energy resources at the center of public interest. Solar energy is one of the most promising renewable energy resources. Sun trackers can substantially improve the electricity production of a photovoltaic (PV) system. This paper proposes a novel design of a dual-axis solar tracking PV system which utilizes the feedback control theory along with a four-quadrant light dependent resistor (LDR) sensor and simple electronic circuits to provide robust system performance. The proposed system uses a unique dual-axis AC motor and a stand-alone PV inverter to accomplish solar tracking. The control implementation is a technical innovation that is a simple and effective design. In addition, a scaled-down laboratory prototype is constructed to verify the feasibility of the scheme. The effectiveness of the Sun tracker is confirmed experimentally. To conclude, the results of this study may serve as valuable references for future solar energy applications. PMID:23467030

  9. Two-dimensional Forster resonance energy transfer (2-D FRET) and the membrane raft hypothesis

    OpenAIRE

    Acasandrei, Maria; Dale, Robert; VAN DE VEN, Martin; AMELOOT, Marcel

    2006-01-01

    A model for analyzing Forster resonance energy transfer (FRET) data in relation to the cell plasma membrane raft hypothesis is developed to take into account: (a) the distribution of FRET donors and acceptors at the surface of probing antibody fragments specific for a putative raft component; (b) partitioning of the raft component between raft and non-raft areas of the membrane; and (c) the dependence of the raft partition on the expression level of the considered component. Analysis of relev...

  10. Classic maximum entropy recovery of the average joint distribution of apparent FRET efficiency and fluorescence photons for single-molecule burst measurements.

    Science.gov (United States)

    DeVore, Matthew S; Gull, Stephen F; Johnson, Carey K

    2012-04-05

    We describe a method for analysis of single-molecule Förster resonance energy transfer (FRET) burst measurements using classic maximum entropy. Classic maximum entropy determines the Bayesian inference for the joint probability describing the total fluorescence photons and the apparent FRET efficiency. The method was tested with simulated data and then with DNA labeled with fluorescent dyes. The most probable joint distribution can be marginalized to obtain both the overall distribution of fluorescence photons and the apparent FRET efficiency distribution. This method proves to be ideal for determining the distance distribution of FRET-labeled biomolecules, and it successfully predicts the shape of the recovered distributions.

  11. Branched DNA nanostructures efficiently stabilised and monitored by novel pyrene-perylene 2'-α-l-amino-LNA FRET pairs

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Santhosh Kumar, T; Campbell, Meghan A

    2013-01-01

    Novel pyrene-perylene α-l-LNA FRET pairs described herein effectively detect assembly of 2- and 3-way branched DNA nanostructures prepared by postsynthetic microwave-assisted CuAAC click chemistry. The fluorescent signalling of assembly by internally positioned FRET pairs is achieved with low...

  12. A method to quantify FRET stoichiometry with phasor plot analysis and acceptor lifetime ingrowth.

    Science.gov (United States)

    Chen, WeiYue; Avezov, Edward; Schlachter, Simon C; Gielen, Fabrice; Laine, Romain F; Harding, Heather P; Hollfelder, Florian; Ron, David; Kaminski, Clemens F

    2015-03-10

    FRET is widely used for the study of protein-protein interactions in biological samples. However, it is difficult to quantify both the FRET efficiency (E) and the affinity (Kd) of the molecular interaction from intermolecular FRET signals in samples of unknown stoichiometry. Here, we present a method for the simultaneous quantification of the complete set of interaction parameters, including fractions of bound donors and acceptors, local protein concentrations, and dissociation constants, in each image pixel. The method makes use of fluorescence lifetime information from both donor and acceptor molecules and takes advantage of the linear properties of the phasor plot approach. We demonstrate the capability of our method in vitro in a microfluidic device and also in cells, via the determination of the binding affinity between tagged versions of glutathione and glutathione S-transferase, and via the determination of competitor concentration. The potential of the method is explored with simulations. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Fluorophores, environments, and quantification techniques in the analysis of transmembrane helix interaction using FRET.

    Science.gov (United States)

    Khadria, Ambalika S; Senes, Alessandro

    2015-07-01

    Förster resonance energy transfer (FRET) has been widely used as a spectroscopic tool in vitro to study the interactions between transmembrane (TM) helices in detergent and lipid environments. This technique has been instrumental to many studies that have greatly contributed to quantitative understanding of the physical principles that govern helix-helix interactions in the membrane. These studies have also improved our understanding of the biological role of oligomerization in membrane proteins. In this review, we focus on the combinations of fluorophores used, the membrane mimetic environments, and measurement techniques that have been applied to study model systems as well as biological oligomeric complexes in vitro. We highlight the different formalisms used to calculate FRET efficiency and the challenges associated with accurate quantification. The goal is to provide the reader with a comparative summary of the relevant literature for planning and designing FRET experiments aimed at measuring TM helix-helix associations. © 2015 Wiley Periodicals, Inc.

  14. Wide-field lifetime-based FRET imaging for the assessment of early functional distribution of transferrin-based delivery in breast tumor-bearing small animals

    Science.gov (United States)

    Sinsuebphon, Nattawut; Rudkouskaya, Alena; Barroso, Margarida; Intes, Xavier

    2016-02-01

    Targeted drug delivery is a critical aspect of successful cancer therapy. Assessment of dynamic distribution of the drug provides relative concentration and bioavailability at the target tissue. The most common approach of the assessment is intensity-based imaging, which only provides information about anatomical distribution. Observation of biomolecular interactions can be performed using Förster resonance energy transfer (FRET). Thus, FRET-based imaging can assess functional distribution and provide potential therapeutic outcomes. In this study, we used wide-field lifetime-based FRET imaging for the study of early functional distribution of transferrin delivery in breast cancer tumor models in small animals. Transferrin is a carrier for cancer drug delivery. Its interaction with its receptor is within a few nanometers, which is suitable for FRET. Alexa Fluor® 700 and Alexa Fluor® 750 were conjugated to holo-transferrin which were then administered via tail vein injection to the mice implanted with T47D breast cancer xenografts. Images were continuously acquired for 60 minutes post-injection. The results showed that transferrin was primarily distributed to the liver, the urinary bladder, and the tumor. The cellular uptake of transferrin, which was indicated by the level of FRET, was high in the liver but very low in the urinary bladder. The results also suggested that the fluorescence intensity and FRET signals were independent. The liver showed increasing intensity and increasing FRET during the observation period, while the urinary bladder showed increasing intensity but minimal FRET. Tumors gave varied results corresponding to their FRET progression. These results were relevant to the biomolecular events that occurred in the animals.

  15. Les vicissitudes du fret ferroviaire

    OpenAIRE

    DABLANC, L

    2010-01-01

    Dans beaucoup de pays européens, et plus encore en Amérique du Nord et en Asie, le transport de marchandises par le train a augmenté depuis dix ans. Cette activité réduit la part des marchandises acheminées par la route et contribue ainsi au développement durable : un camion émet 8 à 30 fois plus de dioxyde de carbone que le train, pour une distance et une quantité transportée équivalentes. Pourtant, la France a raté ce renouveau. Filiale du groupe public SNCF, la Société Fret SNCF, qui assur...

  16. Development of device for grid spring fatigue and a cell-based fuel rod fretting wear tests

    International Nuclear Information System (INIS)

    Kim, Hyung Kyu; Yoon, Kyung Ho; Kang, Heung Seok; Song, Kee Nam

    2001-05-01

    As an activity of experimental research on the cause and the remedy of LWR fuel fretting failure, developed is test equipment for fatigue of grid spring and cell-based fuel rod fretting wear test. The equipment enables to perform the fretting wear test in the case of gap existence between spring and cladding, which has not been possible by the previously developed one (KAERI/TR-1570/2000). It can also provide fatigue test capability with the frequency of more than 10 Hz. Used are a servo-motor, an eccentric cylinder and lever mechanism for driving system as was similarly used for the previous equipment. In fretting wear test, up to 2 span-length of a fuel cladding tube can be accommodated. For fatigue test, on the other hand, a device for clamping the spring fixture is installed additionally. As a feature of the present equipment, the gap or the contacting force between a spring and a tube can be adjusted during the fretting wear test, while an initial spring force can be simulated for the fatigue test. Tests will be conducted in air at room temperature. In this report, every part of the equipment is explained with photographs, which will provide an easy understanding. Test procedure such as specimen installation, sequence of operation and program handling is also given. As a performance test of the present equipment, displacement range is measured when the hinge of the lever locates at its maximum and minimum positions. This will be used as basic information when additional eccentric cylinder is necessary for different displacement ranges

  17. Highly sensitive and quantitative FRET-FLIM imaging in single dendritic spines using improved non-radiative YFP.

    Science.gov (United States)

    Murakoshi, Hideji; Lee, Seok-Jin; Yasuda, Ryohei

    2008-08-01

    Two-photon fluorescence lifetime imaging microscopy (TPFLIM) enables the quantitative measurements of fluorescence resonance energy transfer (FRET) in small subcellular compartments in light scattering tissue. We evaluated and optimized the FRET pair of mEGFP (monomeric EGFP with the A206K mutation) and REACh (non-radiative YFP variants) for TPFLIM. We characterized several mutants of REACh in terms of their "darkness," and their ability to act as a FRET acceptor for mEGFP in HeLa cells and hippocampal neurons. Since the commonly used monomeric mutation A206K increases the brightness of REACh, we introduced a different monomeric mutation (F223R) which does not affect the brightness. Also, we found that the folding efficiency of original REACh, as measured by the fluorescence lifetime of a mEGFP-REACh tandem dimer, was low and variable from cell to cell. Introducing two folding mutations (F46L, Q69M) into REACh increased the folding efficiency by approximately 50%, and reduced the variability of FRET signal. Pairing mEGFP with the new REACh (super-REACh, or sREACh) improved the signal-to-noise ratio compared to the mEGFP-mRFP or mEGFP-original REACh pair by approximately 50%. Using this new pair, we demonstrated that the fraction of actin monomers in filamentous and globular forms in single dendritic spines can be quantitatively measured with high sensitivity. Thus, the mEGFP-sREACh pair is suited for quantitative FRET measurement by TPFLIM, and enables us to measure protein-protein interactions in individual dendritic spines in brain slices with high sensitivity.

  18. Noninvasive High-Throughput Single-Cell Analysis of HIV Protease Activity Using Ratiometric Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Rok Gaber

    2013-11-01

    Full Text Available To effectively fight against the human immunodeficiency virus infection/ acquired immunodeficiency syndrome (HIV/AIDS epidemic, ongoing development of novel HIV protease inhibitors is required. Inexpensive high-throughput screening assays are needed to quickly scan large sets of chemicals for potential inhibitors. We have developed a Förster resonance energy transfer (FRET-based, HIV protease-sensitive sensor using a combination of a fluorescent protein pair, namely mCerulean and mCitrine. Through extensive in vitro characterization, we show that the FRET-HIV sensor can be used in HIV protease screening assays. Furthermore, we have used the FRET-HIV sensor for intracellular quantitative detection of HIV protease activity in living cells, which more closely resembles an actual viral infection than an in vitro assay. We have developed a high-throughput method that employs a ratiometric flow cytometry for analyzing large populations of cells that express the FRET-HIV sensor. The method enables FRET measurement of single cells with high sensitivity and speed and should be used when subpopulation-specific intracellular activity of HIV protease needs to be estimated. In addition, we have used a confocal microscopy sensitized emission FRET technique to evaluate the usefulness of the FRET-HIV sensor for spatiotemporal detection of intracellular HIV protease activity.

  19. Noninvasive High-Throughput Single-Cell Analysis of HIV Protease Activity Using Ratiometric Flow Cytometry

    Science.gov (United States)

    Gaber, Rok; Majerle, Andreja; Jerala, Roman; Benčina, Mojca

    2013-01-01

    To effectively fight against the human immunodeficiency virus infection/acquired immunodeficiency syndrome (HIV/AIDS) epidemic, ongoing development of novel HIV protease inhibitors is required. Inexpensive high-throughput screening assays are needed to quickly scan large sets of chemicals for potential inhibitors. We have developed a Förster resonance energy transfer (FRET)-based, HIV protease-sensitive sensor using a combination of a fluorescent protein pair, namely mCerulean and mCitrine. Through extensive in vitro characterization, we show that the FRET-HIV sensor can be used in HIV protease screening assays. Furthermore, we have used the FRET-HIV sensor for intracellular quantitative detection of HIV protease activity in living cells, which more closely resembles an actual viral infection than an in vitro assay. We have developed a high-throughput method that employs a ratiometric flow cytometry for analyzing large populations of cells that express the FRET-HIV sensor. The method enables FRET measurement of single cells with high sensitivity and speed and should be used when subpopulation-specific intracellular activity of HIV protease needs to be estimated. In addition, we have used a confocal microscopy sensitized emission FRET technique to evaluate the usefulness of the FRET-HIV sensor for spatiotemporal detection of intracellular HIV protease activity. PMID:24287545

  20. From PII signaling to metabolite sensing: a novel 2-oxoglutarate sensor that details PII-NAGK complex formation.

    Directory of Open Access Journals (Sweden)

    Jan Lüddecke

    Full Text Available The widespread PII signal transduction proteins are known for integrating signals of nitrogen and energy supply and regulating cellular behavior by interacting with a multitude of target proteins. The PII protein of the cyanobacterium Synechococcus elongatus forms complexes with the controlling enzyme of arginine synthesis, N-acetyl-L-glutamate kinase (NAGK in a 2-oxoglutarate- and ATP/ADP-dependent manner. Fusing NAGK and PII proteins to either CFP or YFP yielded a FRET sensor that specifically responded to 2-oxoglutarate. The impact of the fluorescent tags on PII and NAGK was evaluated by enzyme assays, surface plasmon resonance spectroscopy and isothermal calorimetric experiments. The developed FRET sensor provides real-time data on PII - NAGK interaction and its modulation by the effector molecules ATP, ADP and 2-oxoglutarate in vitro. Additionally to its utility to monitor 2-oxoglutarate levels, the FRET assay provided novel insights into PII - NAGK complex formation: (i It revealed the formation of an encounter-complex between PII and NAGK, which holds the proteins in proximity even in the presence of inhibitors of complex formation; (ii It revealed that the PII T-loop residue Ser49 is neither essential for complex formation with NAGK nor for activation of the enzyme but necessary to form a stable complex and efficiently relieve NAGK from arginine inhibition; (iii It showed that arginine stabilizes the NAGK hexamer and stimulates PII - NAGK interaction.

  1. Ratiometric Fluorescent Detection of Pb2+ by FRET-Based Phthalocyanine-Porphyrin Dyads.

    Science.gov (United States)

    Zhang, Dongli; Zhu, Mengliang; Zhao, Luyang; Zhang, Jinghui; Wang, Kang; Qi, Dongdong; Zhou, Yang; Bian, Yongzhong; Jiang, Jianzhuang

    2017-12-04

    Sensitive and selective detection of Pb 2+ is a very worthwhile endeavor in terms of both human health and environmental protection, as the heavy metal is fairly ubiquitous and highly toxic. In this study, we designed phthalocyanine-porphyrin (Pc-Por) heterodyads, namely, H 2 Pc-α-ZnPor (1) and H 2 Pc-β-ZnPor (2), by connecting a zinc(II) porphyrin moiety to the nonperipheral (α) or peripheral (β) position of a metal-free phthalocyanine moiety. Upon excitation at the porphyrin Soret region (420 nm), both of the dyads exhibited not only a porphyrin emission (605 nm) but also a phthalocyanine emission (ca. 700 nm), indicating the occurrence of intramolecular fluorescence resonance energy transfer (FRET) processes from the porphyrin donor to the phthalocyanine acceptor. The dyads can selectively bind Pb 2+ in the phthalocyanine core leading to a red shift of the phthalocyanine absorption and thus a decrease of spectral overlap between the porphyrin emission and phthalocyanine absorption, which in turn suppresses the intramolecular FRET. In addition, the binding of Pb 2+ can highly quench the emission of phthalocyanine by heavy-metal ion effects. The synergistic coupled functions endow the dyads with remarkable ratiometric fluorescent responses at two distinct wavelengths (F 605 /F 703 for 1 and F 605 /F 700 for 2). The emission intensity ratio increased as a linear function to the concentration of Pb 2+ in the range of 0-4.0 μM, whereas the detection limits were determined to be 3.4 × 10 -9 and 2.2 × 10 -8 M for 1 and 2, respectively. Furthermore, by comparative study of 1 and 2, the effects of distance and relative orientation between Pc and ZnPor fluorophores on the FRET efficiency and sensing performance were highlighted, which is helpful for further optimizing such FRET systems.

  2. Fretting corrosion tests on orthopedic plates and screws made of ASTM F138 stainless steel

    OpenAIRE

    Santos,Claudio Teodoro dos; Barbosa,Cássio; Monteiro,Maurício de Jesus; Abud,Ibrahim de Cerqueira; Caminha,Ieda Maria Vieira; Roesler,Carlos Rodrigo de Mello

    2015-01-01

    Introduction Although there has been significant progress in the design of implants for osteosynthesis, the occurrence of failures in these medical devices are still frequent. These implants are prone to suffer from fretting corrosion due to micromotion that takes place between the screw heads and plate holes. Consequently, fretting corrosion has been the subject of research in order to understand its influence on the structural integrity of osteosynthesis implants. The aim of this paper is t...

  3. Fretting Wear Behaviors of Aluminum Cable Steel Reinforced (ACSR Conductors in High-Voltage Transmission Line

    Directory of Open Access Journals (Sweden)

    Xingchi Ma

    2017-09-01

    Full Text Available This work reports the fretting wear behavior of aluminum cable steel reinforced (ACSR conductors for use in high-voltage transmission line. Fretting wear tests of Al wires were conducted on a servo-controlled fatigue testing machine with self-made assistant apparatus, and their fretting process characteristics, friction force, wear damage, and wear surface morphology were detailed analyzed. The results show that the running regime of Al wires changes from a gross slip regime to a mixed regime more quickly as increasing contact load. With increasing amplitudes, gross slip regimes are more dominant under contact loads of lower than 30 N. The maximum friction force is relatively smaller in the NaCl solution than in a dry friction environment. The primary wear mechanisms in dry friction environments are abrasive wear and adhesive wear whereas abrasive wear and fatigue damage are dominant in NaCl solution.

  4. Tunable Polymer Fiber Bragg Grating (FBG) Inscription: Fabrication of Dual-FBG Temperature Compensated Polymer Optical Fiber Strain Sensors

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2012-01-01

    We demonstrate stable wavelength tunable inscription of polymer optical fiber Bragg gratings (FBGs). By straining the fiber during FBG inscription, we linearly tune the center wavelength over 7 nm with less than 1% strain. Above 1% strain, the tuning curve saturates and we show a maximum tuning...... of 12 nm with 2.25% strain. We use this inscription method to fabricate a dual-FBG strain sensor in a poly (methyl methacrylate) single-mode microstructured polymer optical fiber and demonstrate temperature compensated strain sensing around 850 nm....

  5. Ratiometric FRET-based detection of DNA and micro-RNA in solution

    International Nuclear Information System (INIS)

    Matveeva, Evgenia G.; Gryczynski, Zygmunt; Stewart, Donald R.; Gryczynski, Ignacy

    2009-01-01

    A ratiometric method for detecting DNA oligomers in bulk solution based on Foerster resonance energy transfer (FRET) is described. The two fluorescence signals (green and red), originating from Cy3 (donor, green) and Cy5 (acceptor, red) labels, are simultaneously detected from the pre-hybridized Cy3oligomerY:Cy5oligomerX system. The ratio of red to green intensities is sensitive to the presence of the single-stranded complimentary oligomer, which replaces single-stranded Cy3oligomerY in the donor:acceptor complex and perturbs the FRET. The detection scheme is generally applicable to the detection of DNA and RNA, and particularly micro-RNA. The proposed method is applicable to various double-stranded various lengths targets (manipulation of the sample preparation conditions, such as temperature, incubation time, denaturizing agent, may be needed).

  6. Electroporation and microinjection successfully deliver single-stranded and duplex DNA into live cells as detected by FRET measurements.

    Directory of Open Access Journals (Sweden)

    Rosemary A Bamford

    Full Text Available Förster resonance energy transfer (FRET technology relies on the close proximity of two compatible fluorophores for energy transfer. Tagged (Cy3 and Cy5 complementary DNA strands forming a stable duplex and a doubly-tagged single strand were shown to demonstrate FRET outside of a cellular environment. FRET was also observed after transfecting these DNA strands into fixed and live cells using methods such as microinjection and electroporation, but not when using lipid based transfection reagents, unless in the presence of the endosomal acidification inhibitor bafilomycin. Avoiding the endocytosis pathway is essential for efficient delivery of intact DNA probes into cells.

  7. FRET microscopy autologous tumor lysate processing in mature dendritic cell vaccine therapy

    Directory of Open Access Journals (Sweden)

    Ridolfi Ruggero

    2010-06-01

    Full Text Available Abstract Background Antigen processing by dendritic cells (DC exposed to specific stimuli has been well characterized in biological studies. Nonetheless, the question of whether autologous whole tumor lysates (as used in clinical trials are similarly processed by these cells has not yet been resolved. Methods In this study, we examined the transfer of peptides from whole tumor lysates to major histocompatibility complex class II molecules (MHC II in mature dendritic cells (mDC from a patient with advanced melanoma. Tumor antigenic peptides-MHC II proximity was revealed by Förster Resonance Energy Transfer (FRET measurements, which effectively extends the application of fluorescence microscopy to the molecular level ( Results We detected significant energy transfer between donor and acceptor-labelled antibodies against HLA-DR at the membrane surface of mDC. FRET data indicated that fluorescent peptide-loaded MHC II molecules start to accumulate on mDC membranes at 16 hr from the maturation stimulus, steeply increasing at 22 hr with sustained higher FRET detected up to 46 hr. Conclusions The results obtained imply that the patient mDC correctly processed the tumor specific antigens and their display on the mDC surface may be effective for several days. These observations support the rationale for immunogenic efficacy of autologous tumor lysates.

  8. Fretting Wear Damage Mechanism of Uranium under Various Atmosphere and Vacuum Conditions

    Directory of Open Access Journals (Sweden)

    Zhengyang Li

    2018-04-01

    Full Text Available A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O2 + 78% N2, and O2 and vacuum conditions (1.05 and 1 × 10−4 Pa. Evolution of friction was assessed by coefficient of friction (COF and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 107 μm3. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 106 μm3. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles.

  9. Dual Wake-up Low Power Listening for Duty Cycled Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jongkeun Na

    2008-01-01

    Full Text Available Energy management is an interesting research area for wireless sensor networks. Relevant dutycycling (or sleep scheduling algorithm has been actively studied at MAC, routing, and application levels. Low power listening (LPL MAC is one of effective dutycycling techniques. This paper proposes a novel approach called dual wake-up LPL (DW-LPL. Existing LPL scheme uses a preamble detection method for both broadcast and unicast, thus suffers from severe overhearing problem at unicast transmission. DW-LPL uses a different wake-up method for unicast while using LPL-like method for broadcast; DW-LPL introduces a receiver-initiated method in which a sender waits a signal from receiver to start unicast transmission, which incurs some signaling overhead but supports flexible adaptive listening as well as overhearing removal effect. Through analysis and Mote (Telosb experiment, we show that DW-LPL provides more energy saving than LPL and our adaptive listening scheme is effective for energy conservation in practical network topologies and traffic patterns.

  10. Dual Wake-up Low Power Listening for Duty Cycled Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Lim Sangsoon

    2008-01-01

    Full Text Available Abstract Energy management is an interesting research area for wireless sensor networks. Relevant dutycycling (or sleep scheduling algorithm has been actively studied at MAC, routing, and application levels. Low power listening (LPL MAC is one of effective dutycycling techniques. This paper proposes a novel approach called dual wake-up LPL (DW-LPL. Existing LPL scheme uses a preamble detection method for both broadcast and unicast, thus suffers from severe overhearing problem at unicast transmission. DW-LPL uses a different wake-up method for unicast while using LPL-like method for broadcast; DW-LPL introduces a receiver-initiated method in which a sender waits a signal from receiver to start unicast transmission, which incurs some signaling overhead but supports flexible adaptive listening as well as overhearing removal effect. Through analysis and Mote (Telosb experiment, we show that DW-LPL provides more energy saving than LPL and our adaptive listening scheme is effective for energy conservation in practical network topologies and traffic patterns.

  11. Fretting fatigue life estimation using fatigue damage gradient correction factor in various contact configurations

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dong Hyeon; Cho, Sung-San [Hongik University, Seoul (Korea, Republic of)

    2017-03-15

    A fretting fatigue life estimation method that takes into account the stress gradient effect was developed by the authors [Journal of Mechanical Science and Technology, 28 (2014) 2153-2159]. In the developed method, fatigue damage value at the cracking location is corrected with fatigue damage gradient and the corrected value is compared directly with the plain fatigue data for life estimation. In other words, the correction factor is the ratio of plain fatigue damage to fretting fatigue damage at the same life and a function of fatigue damage gradient. Since reliability of the method was verified only for cylinder-on-flat contact configuration in the previous study, the present study extends application of the method to flat-on-flat contact configurations by developing the correction factor for both the contact configuration. Fretting fatigue experiments were conducted to obtain fatigue life data for various fretting pads. Finite element analyses were conducted to evaluate the Smith-Watson-Topper (SWT) fatigue damage parameter in the cracking region. It is revealed that the SWT parameter in fat-on-flat contact configuration decreases exponentially away from the surface as in cylinder-on-flat contact configuration, and thus the SWT gradient at the surface can be evaluated reliably. Moreover, it is found that decrease in the SWT parameter around the cracking location can be expressed by piecewise exponential curves. If the gradient of SWT at the surface is used as a representative value of SWT gradient, it is impossible to establish functional relationship between the SWT gradient and the correction factor for both the contact configurations although it was possible for cylinder-on-flat contact configuration. However, if weighted average of the SWT gradient values obtained from each exponential curve in the piecewise exponential curve is used as a representative value, the correction factor for both the contact configurations becomes a function of the SWT gradient

  12. Development of a Fluorescence Resonance Energy Transfer (FRET)-Based DNA Biosensor for Detection of Synthetic Oligonucleotide of Ganoderma boninense.

    Science.gov (United States)

    Mohd Bakhori, Noremylia; Yusof, Nor Azah; Abdullah, Abdul Halim; Hussein, Mohd Zobir

    2013-12-01

    An optical DNA biosensor based on fluorescence resonance energy transfer (FRET) utilizing synthesized quantum dot (QD) has been developed for the detection of specific-sequence of DNA for Ganoderma boninense, an oil palm pathogen. Modified QD that contained carboxylic groups was conjugated with a single-stranded DNA probe (ssDNA) via amide-linkage. Hybridization of the target DNA with conjugated QD-ssDNA and reporter probe labeled with Cy5 allows for the detection of related synthetic DNA sequence of Ganoderma boninense gene based on FRET signals. Detection of FRET emission before and after hybridization was confirmed through the capability of the system to produce FRET at 680 nm for hybridized sandwich with complementary target DNA. No FRET emission was observed for non-complementary system. Hybridization time, temperature and effect of different concentration of target DNA were studied in order to optimize the developed system. The developed biosensor has shown high sensitivity with detection limit of 3.55 × 10(-9) M. TEM results show that the particle size of QD varies in the range between 5 to 8 nm after ligand modification and conjugation with ssDNA. This approach is capable of providing a simple, rapid and sensitive method for detection of related synthetic DNA sequence of Ganoderma boninense.

  13. Development of a Fluorescence Resonance Energy Transfer (FRET-Based DNA Biosensor for Detection of Synthetic Oligonucleotide of Ganoderma boninense

    Directory of Open Access Journals (Sweden)

    Noremylia Mohd Bakhori

    2013-12-01

    Full Text Available An optical DNA biosensor based on fluorescence resonance energy transfer (FRET utilizing synthesized quantum dot (QD has been developed for the detection of specific-sequence of DNA for Ganoderma boninense, an oil palm pathogen. Modified QD that contained carboxylic groups was conjugated with a single-stranded DNA probe (ssDNA via amide-linkage. Hybridization of the target DNA with conjugated QD-ssDNA and reporter probe labeled with Cy5 allows for the detection of related synthetic DNA sequence of Ganoderma boninense gene based on FRET signals. Detection of FRET emission before and after hybridization was confirmed through the capability of the system to produce FRET at 680 nm for hybridized sandwich with complementary target DNA. No FRET emission was observed for non-complementary system. Hybridization time, temperature and effect of different concentration of target DNA were studied in order to optimize the developed system. The developed biosensor has shown high sensitivity with detection limit of 3.55 × 10−9 M. TEM results show that the particle size of QD varies in the range between 5 to 8 nm after ligand modification and conjugation with ssDNA. This approach is capable of providing a simple, rapid and sensitive method for detection of related synthetic DNA sequence of Ganoderma boninense.

  14. Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

    Science.gov (United States)

    Deen, David A.; Osinsky, Andrei; Miller, Ross

    2014-03-01

    A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection.

  15. Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

    International Nuclear Information System (INIS)

    Deen, David A.; Osinsky, Andrei; Miller, Ross

    2014-01-01

    A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection

  16. Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

    Energy Technology Data Exchange (ETDEWEB)

    Deen, David A.; Osinsky, Andrei; Miller, Ross [Agnitron Technology Incorporated, Eden Prairie, Minnesota 55346 (United States)

    2014-03-03

    A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection.

  17. Deployment and evaluation of a dual-sensor autofocusing method for on-machine measurement of patterns of small holes on freeform surfaces.

    Science.gov (United States)

    Chen, Xiaomei; Longstaff, Andrew; Fletcher, Simon; Myers, Alan

    2014-04-01

    This paper presents and evaluates an active dual-sensor autofocusing system that combines an optical vision sensor and a tactile probe for autofocusing on arrays of small holes on freeform surfaces. The system has been tested on a two-axis test rig and then integrated onto a three-axis computer numerical control (CNC) milling machine, where the aim is to rapidly and controllably measure the hole position errors while the part is still on the machine. The principle of operation is for the tactile probe to locate the nominal positions of holes, and the optical vision sensor follows to focus and capture the images of the holes. The images are then processed to provide hole position measurement. In this paper, the autofocusing deviations are analyzed. First, the deviations caused by the geometric errors of the axes on which the dual-sensor unit is deployed are estimated to be 11 μm when deployed on a test rig and 7 μm on the CNC machine tool. Subsequently, the autofocusing deviations caused by the interaction of the tactile probe, surface, and small hole are mathematically analyzed and evaluated. The deviations are a result of the tactile probe radius, the curvatures at the positions where small holes are drilled on the freeform surface, and the effect of the position error of the hole on focusing. An example case study is provided for the measurement of a pattern of small holes on an elliptical cylinder on the two machines. The absolute sum of the autofocusing deviations is 118 μm on the test rig and 144 μm on the machine tool. This is much less than the 500 μm depth of field of the optical microscope. Therefore, the method is capable of capturing a group of clear images of the small holes on this workpiece for either implementation.

  18. Fluorescence lifetime FRET imaging of receptor-ligand complexes in tumor cells in vitro and in vivo

    Science.gov (United States)

    Rudkouskaya, Alena; Sinsuebphon, Nattawut; Intes, Xavier; Mazurkiewicz, Joseph E.; Barroso, Margarida

    2017-02-01

    To guide the development of targeted therapies with improved efficacy and accelerated clinical acceptance, novel imaging methodologies need to be established. Toward this goal, fluorescence lifetime Förster resonance energy transfer (FLIM-FRET) imaging assays capitalize on the ability of antibodies or protein ligands to bind dimerized membrane bound receptors to measure their target engagement levels in cancer cells. Conventional FLIM FRET microscopy has been widely applied at visible wavelengths to detect protein-protein interactions in vitro. However, operation at these wavelengths restricts imaging quality and ability to quantitate lifetime changes in in vivo small animal optical imaging due to high auto-fluorescence and light scattering. Here, we have analyzed the uptake of iron-bound transferrin (Tf) probes into human breast cancer cells using FLIM-FRET microscopy in the visible and near-infrared (NIR) range. The development of NIR FLIM FRET microscopy allows for the use of quantitative lifetime-based molecular assays to measure drug-target engagement levels at multiple scales: from in vitro microscopy to in vivo small animal optical imaging (macroscopy). This novel approach can be extended to other receptors, currently targeted in oncology. Hence, lifetime-based molecular imaging can find numerous applications in drug delivery and targeted therapy assessment and optimization.

  19. A dansyl-rhodamine ratiometric fluorescent probe for Hg2+ based on FRET mechanism.

    Science.gov (United States)

    Xie, Puhui; Guo, Fengqi; Wang, Lingyu; Yang, Sen; Yao, Denghui; Yang, Guoyu

    2015-03-01

    Based on resonance energy transfer (FRET) from dansyl to rhodamine 101, a new fluorescent probe (compound 1) containing rhodamine 101 and a dansyl unit was synthesized for detecting Hg(2+) through ratiometric sensing in DMSO aqueous solutions. This probe shows a fast, reversible and selective response toward Hg(2+) in a wide pH range. Hg(2+) induced ring-opening reactions of the spirolactam rhodamine moiety of 1, leading to the formation of fluorescent derivatives that can serve as the FRET acceptors. Very large stokes shift (220 nm) was observed in this case. About 97-fold increase in fluorescence intensity ratio was observed upon its binding with Hg(2+).

  20. A low cytotoxic and ratiometric fluorescent nanosensor based on carbon-dots for intracellular pH sensing and mapping

    International Nuclear Information System (INIS)

    Du Fangkai; Ming Yunhao; Zeng Fang; Yu Changmin; Wu Shuizhu

    2013-01-01

    Intracellular pH plays a critical role in the function of cells, and its regulation is essential for most cellular processes. In this study, we demonstrate a fluorescence resonance energy transfer (FRET)-based ratiometric pH nanosensor with carbon-dot (CD) as the carrier. The sensor was prepared by covalently linking a pH-sensitive fluorescent dye (fluorescein isothiocyanate, FITC) onto carbon-dot. As the FRET donor, the carbon-dot exhibits bright fluorescence emission as well as λ ex -dependent photoluminescence emission, and a suitable excitation wavelength for the donor (CD) can be chosen to match the energy acceptor (fluorescein moiety). The fluorescein moieties on a CD undergo structural and spectral conversion as the pH changes, affording the nanoplatform a FRET-based pH sensor. The CD-based system exhibits a significant change in fluorescence intensity ratio between pH 4 and 8 with a pK a value of 5.69. It also displays excellent water dispersibility, good spectral reversibility, satisfactory cell permeability and low cytotoxicity. Following the living cell uptake, this nanoplatform with dual-chromatic emissions can facilitate real-time visualization of the pH evolution involved in the endocytic pathway of the nanosensor. This reversible and low cytotoxic fluorescent nanoplatform may be highly valuable in a variety of biological studies, such as endocytic trafficking, endosome/lysosome maturation, and pH regulation in subcellular organelles. (paper)

  1. Experimental studies of resistance fretting-wear of fuel rods for VVER-1000 and TVS-KVADRAT fuel assemblies

    International Nuclear Information System (INIS)

    Makarov, V.; Afanasiev, A.; Egorov, Yu.; Matvienko, I.

    2015-01-01

    The paper covers the results of the studies performed to justify the wear resistance of fuel rods in contact with the spacer grids of TVS VVER-1000 fuel assembly and TVS-KVADRAT square fuel assembly of Russian design for PWR-900 reactor. The presented results of three testing stages comprise: Testing of mockup fuel rods of VVER TVS fuel assembly for fretting wear under the conditions of the water chemistry of VVER reactor; Testing models of different design embodiments of the fuel rods for VVER TVS fuel assembly for fretting wear in still cold water; Testing mockup fuel rods of TVS-KVADRAT square fuel assembly for PWR reactor for frettingwear under the conditions of PWR water chemistry. The effect of structural and operational factors was determined (amplitudes, fuel rod vibration frequencies, values of cladding-to-spacer grid cell gap for the depth of fuel rod cladding wear etc.), an assessment was made of the threshold values of fuel rod vibration parameters, which, if not exceeded, provide the absence of the fuel rod cladding fretting wear in the fuel rod-to spacer grid contact area. Key words: fretting wear, fuel rod, spacer grid, VVER, PWR (author)

  2. Derivation of Elastic Stress Concentration Factor Equations for Debris Fretting Flaws in Pressure Tubes of Pressurized Heavy Water Reactors

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Oh, Young Jin

    2014-01-01

    If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis

  3. [Detection of protein-protein interactions by FRET and BRET methods].

    Science.gov (United States)

    Matoulková, E; Vojtěšek, B

    2014-01-01

    Nowadays, in vivo protein-protein interaction studies have become preferable detecting meth-ods that enable to show or specify (already known) protein interactions and discover their inhibitors. They also facilitate detection of protein conformational changes and discovery or specification of signaling pathways in living cells. One group of in vivo methods enabling these findings is based on fluorescent resonance energy transfer (FRET) and its bio-luminescent modification (BRET). They are based on visualization of protein-protein interactions via light or enzymatic excitation of fluorescent or bio-luminescent proteins. These methods allow not only protein localization within the cell or its organelles (or small animals) but they also allow us to quantify fluorescent signals and to discover weak or strong interaction partners. In this review, we explain the principles of FRET and BRET, their applications in the characterization of protein-protein interactions and we describe several findings using these two methods that clarify molecular and cellular mechanisms and signals related to cancer biology.

  4. Simulation of FRET dyes allows quantitative comparison against experimental data

    Science.gov (United States)

    Reinartz, Ines; Sinner, Claude; Nettels, Daniel; Stucki-Buchli, Brigitte; Stockmar, Florian; Panek, Pawel T.; Jacob, Christoph R.; Nienhaus, Gerd Ulrich; Schuler, Benjamin; Schug, Alexander

    2018-03-01

    Fully understanding biomolecular function requires detailed insight into the systems' structural dynamics. Powerful experimental techniques such as single molecule Förster Resonance Energy Transfer (FRET) provide access to such dynamic information yet have to be carefully interpreted. Molecular simulations can complement these experiments but typically face limits in accessing slow time scales and large or unstructured systems. Here, we introduce a coarse-grained simulation technique that tackles these challenges. While requiring only few parameters, we maintain full protein flexibility and include all heavy atoms of proteins, linkers, and dyes. We are able to sufficiently reduce computational demands to simulate large or heterogeneous structural dynamics and ensembles on slow time scales found in, e.g., protein folding. The simulations allow for calculating FRET efficiencies which quantitatively agree with experimentally determined values. By providing atomically resolved trajectories, this work supports the planning and microscopic interpretation of experiments. Overall, these results highlight how simulations and experiments can complement each other leading to new insights into biomolecular dynamics and function.

  5. Fretting wear of steam generator tubes: high-temperature tests on AECL rig

    International Nuclear Information System (INIS)

    Guerout, F.; Zbinden, M.

    1993-07-01

    The R and DD has undertaken the study of fretting-wear of Alloy 600 S.G. tubes which occurs by contact with migrating items. The test series was performed in Canada at AECL Research (Atomic Energy of Canada Limited) as part of an exchange program. Four types of configuration were envisaged: a tube-to-drilled hole support contact which provides reference results and three types of tube-to-support contacts which simulate the tube fretting-wear induced by a welding rod, a threaded rod and a knife-edge rod support. This programme is completed by the study of the contact between a S.G. tube and a neighbouring S.G. tube which has been broken after plugging. (authors). 1 tab., 3 refs

  6. A Dual-Linear Kalman Filter for Real-Time Orientation Determination System Using Low-Cost MEMS Sensors.

    Science.gov (United States)

    Zhang, Shengzhi; Yu, Shuai; Liu, Chaojun; Yuan, Xuebing; Liu, Sheng

    2016-02-20

    To provide a long-time reliable orientation, sensor fusion technologies are widely used to integrate available inertial sensors for the low-cost orientation estimation. In this paper, a novel dual-linear Kalman filter was designed for a multi-sensor system integrating MEMS gyros, an accelerometer, and a magnetometer. The proposed filter precludes the impacts of magnetic disturbances on the pitch and roll which the heading is subjected to. The filter can achieve robust orientation estimation for different statistical models of the sensors. The root mean square errors (RMSE) of the estimated attitude angles are reduced by 30.6% under magnetic disturbances. Owing to the reduction of system complexity achieved by smaller matrix operations, the mean total time consumption is reduced by 23.8%. Meanwhile, the separated filter offers greater flexibility for the system configuration, as it is possible to switch on or off the second stage filter to include or exclude the magnetometer compensation for the heading. Online experiments were performed on the homemade miniature orientation determination system (MODS) with the turntable. The average RMSE of estimated orientation are less than 0.4° and 1° during the static and low-dynamic tests, respectively. More realistic tests on two-wheel self-balancing vehicle driving and indoor pedestrian walking were carried out to evaluate the performance of the designed MODS when high accelerations and angular rates were introduced. Test results demonstrate that the MODS is applicable for the orientation estimation under various dynamic conditions. This paper provides a feasible alternative for low-cost orientation determination.

  7. Dual-mode fluorophore-doped nickel nitrilotriacetic acid-modified silica nanoparticles combine histidine-tagged protein purification with site-specific fluorophore labeling.

    Science.gov (United States)

    Kim, Sung Hoon; Jeyakumar, M; Katzenellenbogen, John A

    2007-10-31

    We present the first example of a fluorophore-doped nickel chelate surface-modified silica nanoparticle that functions in a dual mode, combining histidine-tagged protein purification with site-specific fluorophore labeling. Tetramethylrhodamine (TMR)-doped silica nanoparticles, estimated to contain 700-900 TMRs per ca. 23 nm particle, were surface modified with nitrilotriacetic acid (NTA), producing TMR-SiO2-NTA-Ni2+. Silica-embedded TMR retains very high quantum yield, is resistant to quenching by buffer components, and is modestly quenched and only to a certain depth (ca. 2 nm) by surface-attached Ni2+. When exposed to a bacterial lysate containing estrogen receptor alpha ligand binding domain (ERalpha) as a minor component, these beads showed very high specificity binding, enabling protein purification in one step. The capacity and specificity of these beads for binding a his-tagged protein were characterized by electrophoresis, radiometric counting, and MALDI-TOF MS. ERalpha, bound to TMR-SiO2-NTA-Ni++ beads in a site-specific manner, exhibited good activity for ligand binding and for ligand-induced binding to coactivators in solution FRET experiments and protein microarray fluorometric and FRET assays. This dual-mode type TMR-SiO2-NTA-Ni2+ system represents a powerful combination of one-step histidine-tagged protein purification and site-specific labeling with multiple fluorophore species.

  8. Accuracy of maximum likelihood estimates of a two-state model in single-molecule FRET

    Energy Technology Data Exchange (ETDEWEB)

    Gopich, Irina V. [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892 (United States)

    2015-01-21

    Photon sequences from single-molecule Förster resonance energy transfer (FRET) experiments can be analyzed using a maximum likelihood method. Parameters of the underlying kinetic model (FRET efficiencies of the states and transition rates between conformational states) are obtained by maximizing the appropriate likelihood function. In addition, the errors (uncertainties) of the extracted parameters can be obtained from the curvature of the likelihood function at the maximum. We study the standard deviations of the parameters of a two-state model obtained from photon sequences with recorded colors and arrival times. The standard deviations can be obtained analytically in a special case when the FRET efficiencies of the states are 0 and 1 and in the limiting cases of fast and slow conformational dynamics. These results are compared with the results of numerical simulations. The accuracy and, therefore, the ability to predict model parameters depend on how fast the transition rates are compared to the photon count rate. In the limit of slow transitions, the key parameters that determine the accuracy are the number of transitions between the states and the number of independent photon sequences. In the fast transition limit, the accuracy is determined by the small fraction of photons that are correlated with their neighbors. The relative standard deviation of the relaxation rate has a “chevron” shape as a function of the transition rate in the log-log scale. The location of the minimum of this function dramatically depends on how well the FRET efficiencies of the states are separated.

  9. New dual emission fluorescent sensor for pH and Pb(II) based on bis(napfthalimide) derivative

    International Nuclear Information System (INIS)

    Pina-Luis, Georgina; Martínez-Quiroz, Marisela; Ochoa-Terán, Adrián; Santacruz-Ortega, Hisila; Mendez-Valenzuela, Eduardo

    2013-01-01

    This paper describes a novel dual emission bis-1,8-naphthalimide sensor for selective determination of pH and Pb 2+ ions. The influence of the variability in the backbone that links the two fluorophores (naphthalimides) as a function of pH and metal ions was studied by UV–visible and fluorescence spectroscopy. Compounds 1(a–d) with different length alkyl linkers (CH 2 ) n (n=1, 2, 4 and 6) showed no excimer formation in aqueous solution. Fluorescence emission of these derivatives varied in a narrow range of pH (5–8) and was only slightly influenced by the addition of metal ions in CH 3 CN solutions. However, derivative 1e with amino-containing spacer (CH 2 –NH–CH 2 ) showed excimer emission in aqueous solution, a wide response to pH (2.5–9.5) and fluorescence enhancement with selective behavior towards metal ions. The pH sensor based in derivative 1e has a sufficient selectivity for practical pH monitoring in the presence of Li + , Na + , K + , Cs + , Ca 2+ , Mg 2+ , Ba 2+ , Cu 2+ , Pb 2+ , Ni 2+ , Zn 2+ and Cd 2+ . The coordination chemistry of these complexes was studied by UV–Vis, fluorescence and 1 H NMR. This chemosensor displayed high selectivity fluorescence enhancement toward Pb 2+ ions in the presence of the metals ions mentioned in CH 3 CN solutions. Competitive assays show that a 1-fold of metal cations in each case, compared with Pb 2+ ions, results in less than ±5% fluorescence intensity changes. Linear calibration up to 1×10 −5 M for Pb(II) ions (R=0.9968) was obtained and detection limit resulted of 5.0×10 −8 M. - Highlights: ► A novel dual emission bis-1,8-naphthalimide sensor for pH and Pb 2+ ions is synthetized. ► The excimer formation depends on the spacer that links the two naphthalimide groups. ► Bis(naphthalimide) with amino-containing spacer showed a wide selective response to pH. ► This chemosensor displayed a selective fluorescence enhancement effect towards Pb 2+ ions. ► Mechanism for the fluorescence OFF

  10. Evaluation of a color fused dual-band NVG

    NARCIS (Netherlands)

    Hogervorst, M.A.; Toet, A.

    2009-01-01

    We designed and evaluated a dual-band Night Vision Goggles sensor system. The sensor system consists of two optically aligned NVGs fitted with filters splitting the sensitive range into a visual and a near-infrared band. The Color-the-night technique (Hogervorst & Toet, FUSION2008) was used to fuse

  11. Preliminary Study on the Fretting Wear Behaviors of a Duel Cooled Fuel Rod

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.H.; Lee, K.H.; Kim, H.K. [KAERI, 150 Dukjin-dong Yuseon-gu Daejeon, 305-353 (Korea, Republic of)

    2009-06-15

    Based on MIT's concept, an innovative fuel development project was launched by KAERI that a substantial power up-rating could be realized by introducing an internally and externally double cooled annular fuel for current PWR reactors. In order to apply this duel cooled fuel to an OPR 1000 reactor system, geometrical features of structural parts in a fuel assembly should be changed except an overall dimension of a fuel assembly. Typical changes are summarized as fuel rod diameter and weight, shape and position of a spacer grid spring, etc. When considering a duel cooled fuel rod, its vibration characteristic and fretting behavior should be verified because the modified shape and dimension of spacer grid spring, fuel rod diameter and weight, number of spacer grid assembly are closely related to a flow-induced vibration in a duel cooled fuel assembly. In this study, based on FIV test results of 4x4 fuel assembly, fretting wear tests of an outer duel cooled fuel rod were performed by using an embossing type spacer grid spring that could adjust its spring stiffness. The discussion was focused on the evaluation of the optimized spring stiffness and spring position in 1x1 cell by analyzing the fretting wear results. (authors)

  12. One-step synthesis of DNA functionalized cadmium-free quantum dots and its application in FRET-based protein sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cuiling, E-mail: clzhang@chem.ecnu.edu.cn [Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241 (China); Ding, Caiping [Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241 (China); Zhou, Guohua [School of Chemistry and Chemical Engineering, Lingnan Normal University, Zhanjiang, 524048 (China); Xue, Qin [Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241 (China); Xian, Yuezhong, E-mail: yzxian@chem.ecnu.edu.cn [Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241 (China)

    2017-03-08

    DNA functionalized quantum dots (QDs) are promising nanoprobes for the fluorescence resonance energy transfer (FRET)-based biosensing. Herein, cadmium-free DNA functionalized Mn-doped ZnS (DNA-ZnS:Mn{sup 2+}) QDs were successfully synthesized by one-step route. As-synthesized QDs show excellent photo-stability with the help of PAA and DNA. Then, we constructed a novel FRET model based on the QDs and WS{sub 2} nanosheets as the energy donor-acceptor pairs, which was successfully applied for the protein detection through the terminal protection of small molecule-linked DNA assay. This work not only explores the potential bioapplication of the DNA-ZnS:Mn{sup 2+} QDs, but also provides a platform for the investigation of small molecule-protein interaction. - Highlights: • The stable and cadmium-free DNA functionalized ZnS:Mn{sup 2+} QDs were successfully synthesized through a facile one-step route. • We constructed a novel FRET system based on one-step synthesized DNA-ZnS:Mn{sup 2+} QDs (donor) and WS{sub 2} nanosheets (acceptor). • The FRET-based strategy was applied for the detection of streptavidin and folate receptor by combining TPSMLD and Exo III.

  13. The Design of Dual-Emissive Composite Material [Zn2(HL)3]+@MOF-5 as Self-Calibrating Luminescent Sensors of Al3+ Ions and Monoethanolamine.

    Science.gov (United States)

    Wu, Meng-Meng; Wang, Jiao-Yang; Sun, Rui; Zhao, Cui; Zhao, Jiong-Peng; Che, Guang-Bo; Liu, Fu-Chen

    2017-08-21

    Introducing another chromophore into a luminescent MOF is a potential way to assembling novel dual-emissive luminescent materials. Putting the chromophore, for which luminescence can be enhanced by Zn 2+ ion, into MOF-5 by the "bottle around ship" strategy is a simple but efficient synthesis method to realize such dual-emissive materials. According to this strategy, a novel dual-emissive luminescent composite material [Zn 2 (HL) 3 ] + @MOF-5 was constructed by loading the [La 3 (HL) 2 L 2 (NO 3 ) 3 H 2 O] (1) (H 2 L = 7,7'-(ethane-1,1'-diyl)8-hydro-quinoline) into MOF-5, in which the [Zn 2 (HL) 3 ] + anions were transformed from 1 with the existence of Zn 2+ . The dual-emissive composite materials show excellent luminescence with two emissions of MOF-5 at 410 nm and [Zn 2 (HL) 3 ] + at 524 nm. Furthermore, by combining characteristics of MOF-5 and the guest chromophore, the composite material is highly selectively sensitive toward Al 3+ and monoethanolamine, which makes [Zn 2 (HL) 3 ] + @MOF-5 a potential self-calibrated fluorescence sensor.

  14. Genetically encoded pH sensor for tracking surface proteins through endocytosis.

    Science.gov (United States)

    Grover, Anmol; Schmidt, Brigitte F; Salter, Russell D; Watkins, Simon C; Waggoner, Alan S; Bruchez, Marcel P

    2012-05-14

    Traffic cam: a tandem dye prepared from a FRET acceptor and a fluorogenic donor functions as a cell surface ratiometric pH indicator, which upon internalization serves to follow protein trafficking during endocytosis. This sensor was used to analyze agonist-dependent internalization of β(2)-adrenergic receptors. It was also used as a surrogate antigen to reveal direct surface-to-endosome antigen transfer between dendritic cells (not shown). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The synergy of corrosion and fretting wear process on Inconel 690 in the high temperature high pressure water environment

    Science.gov (United States)

    Wang, Zihao; Xu, Jian; Li, Jie; Xin, Long; Lu, Yonghao; Shoji, Tetsuo; Takeda, Yoichi; Otsuka, Yuichi; Mutoh, Yoshiharu

    2018-04-01

    The synergistic effect of corrosion and fretting process of the steam generator (SG) tube was investigated by using a self-designed high temperature test rig in this paper. The experiments were performed at 100°C , 200°C and 288°C , respectively. The fretting corrosion damage was studied by optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Raman spectroscopy and auger electron spectroscopy (AES). The results demonstrated that the corrosion process in high temperature high pressure (HTHP) water environment had a distinct interaction with the fretting process of Inconel 690. With the increment of temperature, the damage mechanism changed from a simple mechanical process to a mechanochemical process.

  16. Directed Evolution to Engineer Monobody for FRET Biosensor Assembly and Imaging at Live-Cell Surface.

    Science.gov (United States)

    Limsakul, Praopim; Peng, Qin; Wu, Yiqian; Allen, Molly E; Liang, Jing; Remacle, Albert G; Lopez, Tyler; Ge, Xin; Kay, Brian K; Zhao, Huimin; Strongin, Alex Y; Yang, Xiang-Lei; Lu, Shaoying; Wang, Yingxiao

    2018-04-19

    Monitoring enzymatic activities at the cell surface is challenging due to the poor efficiency of transport and membrane integration of fluorescence resonance energy transfer (FRET)-based biosensors. Therefore, we developed a hybrid biosensor with separate donor and acceptor that assemble in situ. The directed evolution and sequence-function analysis technologies were integrated to engineer a monobody variant (PEbody) that binds to R-phycoerythrin (R-PE) dye. PEbody was used for visualizing the dynamic formation/separation of intercellular junctions. We further fused PEbody with the enhanced CFP and an enzyme-specific peptide at the extracellular surface to create a hybrid FRET biosensor upon R-PE capture for monitoring membrane-type-1 matrix metalloproteinase (MT1-MMP) activities. This biosensor revealed asymmetric distribution of MT1-MMP activities, which were high and low at loose and stable cell-cell contacts, respectively. Therefore, directed evolution and rational design are promising tools to engineer molecular binders and hybrid FRET biosensors for monitoring molecular regulations at the surface of living cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Friction and wear properties of high-velocity oxygen fuel sprayed WC-17Co coating under rotational fretting conditions

    Science.gov (United States)

    Luo, Jun; Cai, Zhenbing; Mo, Jiliang; Peng, Jinfang; Zhu, Minhao

    2016-05-01

    Rotational fretting which exist in many engineering applications has incurred enormous economic loss. Thus, accessible methods are urgently needed to alleviate or eliminate damage by rotational fretting. Surface engineering is an effective approach that is successfully adopted to enhance the ability of components to resist the fretting damage. In this paper, using a high-velocity oxygen fuel sprayed (HVOF) technique WC-17Co coating is deposited on an LZ50 steel surface to study its properties through Vickers hardness testing, scanning electric microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffractrometry (XRD). Rotational fretting wear tests are conducted under normal load varied from 10 N to 50 N, and angular displacement amplitudes vary from 0.125° to 1°. Wear scars are examined using SEM, EDX, optical microscopy (OM), and surface topography. The experimental results reveal that the WC-17Co coating adjusted the boundary between the partial slip regime (PSR) and the slip regime (SR) to the direction of smaller amplitude displacement. As a result, the coefficients of friction are consistently lower than the substrate's coefficients of friction both in the PSR and SR. The damage to the coating in the PSR is very slight. In the SR, the coating exhibits higher debris removal efficiency and load-carrying capacity. The bulge is not found for the coating due to the coating's higher hardness to restrain plastic flow. This research could provide experimental bases for promoting industrial application of WC-17Co coating in prevention of rotational fretting wear.

  18. Real-time biodetection using a smartphone-based dual-color surface plasmon resonance sensor

    Science.gov (United States)

    Liu, Qiang; Yuan, Huizhen; Liu, Yun; Wang, Jiabin; Jing, Zhenguo; Peng, Wei

    2018-04-01

    We proposed a compact and cost-effective red-green dual-color fiber optic surface plasmon resonance (SPR) sensor based on the smartphone. Inherent color selectivity of phone cameras was utilized for real-time monitoring of red and green color channels simultaneously, which can reduce the chance of false detection and improve the sensitivity. Because there are no external prisms, complex optical lenses, or diffraction grating, simple optical configuration is realized. It has a linear response in a refractive index range of 1.326 to 1.351 (R2 = 0.991) with a resolution of 2.3 × 10 - 4 RIU. We apply it for immunoglobulin G (IgG) concentration measurement. Experimental results demonstrate that a linear SPR response was achieved for IgG concentrations varying from 0.02 to 0.30 mg / ml with good repeatability. It may find promising applications in the fields of public health and environment monitoring owing to its simple optics design and applicability in real-time, label-free biodetection.

  19. Characterizing the interactions between prolyl isomerase pin1 and phosphatase inhibitor-2 in living cells with FRET and FCS

    Science.gov (United States)

    Sun, Yuansheng; Wang, Lifu; Jyothikumar, Vinod; Brautigan, David L.; Periasamy, Ammasi

    2012-03-01

    Phosphatase inhibitor-2 (I2) was discovered as a regulator of protein Ser/Thr phosphatase-1 and is conserved from yeast to human. Binding between purified recombinant I2 from different species and the prolyl isomerase Pin1 has been demonstrated with pull-down assays, size exclusion chromatography and nuclear magnetic resonance spectroscopy. Despite this, questions persist as to whether these proteins associate together in living cells. In this study, we prepared fluorescent protein (FP) fusions of I2 and Pin1 and employed both Förster Resonance Energy Transfer (FRET) and Fluorescence Correlation Spectroscopy (FCS) imaging techniques to characterize their interactions in living cells. In both intensity-based and time-resolved FRET studies, we observed FRET uniformly across whole cells co-expressing I2-Cerulean and Pin1-Venus that was significantly higher than in negative controls expressing Cerulean FP (without fusing to I2) as the FRET donor and Pin1-Venus, showing a specific interaction between I2-Cerulean and Pin1-Venus in living cells. We also observed the co-diffusion of I2-Cerulean and Pin1-mCherry in Fluorescence Cross Correlation Spectroscopy (FCCS) measurements. We further showed that I2 itself as well as I2-Pin1 formed complexes in living cells (predicted from in vitro studies) via a quantitative FRET assay, and demonstrated from FCS measurements that both I2 and Pin1 (fused to Cerulean) are highly mobile in living cells.

  20. Energy Efficient Hybrid Dual Axis Solar Tracking System

    Directory of Open Access Journals (Sweden)

    Rashid Ahammed Ferdaus

    2014-01-01

    Full Text Available This paper describes the design and implementation of an energy efficient solar tracking system from a normal mechanical single axis to a hybrid dual axis. For optimizing the solar tracking mechanism electromechanical systems were evolved through implementation of different evolutional algorithms and methodologies. To present the tracker, a hybrid dual-axis solar tracking system is designed, built, and tested based on both the solar map and light sensor based continuous tracking mechanism. These light sensors also compare the darkness and cloudy and sunny conditions assisting daily tracking. The designed tracker can track sun’s apparent position at different months and seasons; thereby the electrical controlling device requires a real time clock device for guiding the tracking system in seeking solar position for the seasonal motion. So the combination of both of these tracking mechanisms made the designed tracker a hybrid one. The power gain and system power consumption are compared with a static and continuous dual axis solar tracking system. It is found that power gain of hybrid dual axis solar tracking system is almost equal to continuous dual axis solar tracking system, whereas the power saved in system operation by the hybrid tracker is 44.44% compared to the continuous tracking system.

  1. Extracting rate coefficients from single-molecule photon trajectories and FRET efficiency histograms for a fast-folding protein.

    Science.gov (United States)

    Chung, Hoi Sung; Gopich, Irina V; McHale, Kevin; Cellmer, Troy; Louis, John M; Eaton, William A

    2011-04-28

    Recently developed statistical methods by Gopich and Szabo were used to extract folding and unfolding rate coefficients from single-molecule Förster resonance energy transfer (FRET) data for proteins with kinetics too fast to measure waiting time distributions. Two types of experiments and two different analyses were performed. In one experiment bursts of photons were collected from donor and acceptor fluorophores attached to a 73-residue protein, α(3)D, freely diffusing through the illuminated volume of a confocal microscope system. In the second, the protein was immobilized by linkage to a surface, and photons were collected until one of the fluorophores bleached. Folding and unfolding rate coefficients and mean FRET efficiencies for the folded and unfolded subpopulations were obtained from a photon by photon analysis of the trajectories using a maximum likelihood method. The ability of the method to describe the data in terms of a two-state model was checked by recoloring the photon trajectories with the extracted parameters and comparing the calculated FRET efficiency histograms with the measured histograms. The sum of the rate coefficients for the two-state model agreed to within 30% with the relaxation rate obtained from the decay of the donor-acceptor cross-correlation function, confirming the high accuracy of the method. Interestingly, apparently reliable rate coefficients could be extracted using the maximum likelihood method, even at low (rate coefficients and mean FRET efficiencies were also obtained in an approximate procedure by simply fitting the FRET efficiency histograms, calculated by binning the donor and acceptor photons, with a sum of three-Gaussian functions. The kinetics are exposed in these histograms by the growth of a FRET efficiency peak at values intermediate between the folded and unfolded peaks as the bin size increases, a phenomenon with similarities to NMR exchange broadening. When comparable populations of folded and unfolded

  2. The Effect of Modulation Ratio of Cu/Ni Multilayer Films on the Fretting Damage Behaviour of Ti-811 Titanium Alloy.

    Science.gov (United States)

    Zhang, Xiaohua; Liu, Daoxin; Li, Xiaoying; Dong, Hanshan; Xi, Yuntao

    2017-05-26

    To improve the fretting damage (fretting wear and fretting fatigue) resistance of Ti-811 titanium alloy, three Cu/Ni multilayer films with the same modulation period thickness (200 nm) and different modulation ratios (3:1, 1:1, 1:3) were deposited on the surface of the alloy via ion-assisted magnetron sputtering deposition (IAD). The bonding strength, micro-hardness, and toughness of the films were evaluated, and the effect of the modulation ratio on the room-temperature fretting wear (FW) and fretting fatigue (FF) resistance of the alloy was determined. The results indicated that the IAD technique can be successfully used to prepare Cu/Ni multilayer films, with high bonding strength, low-friction, and good toughness, which yield improved room-temperature FF and FW resistance of the alloy. For the same modulation period (200 nm), the micro-hardness, friction, and FW resistance of the coated alloy increased, decreased, and improved, respectively, with increasing modulation ratio of the Ni-to-Cu layer thickness. However, the FF resistance of the coated alloy increased non-monotonically with the increasing modulation ratio. Among the three Cu/Ni multilayer films, those with a modulation ratio of 1:1 can confer the highest FF resistance to the Ti-811 alloy, owing mainly to their unique combination of good toughness, high strength, and low-friction.

  3. Fretting wear of Inconel 625 at high temperature and in high vacuum

    International Nuclear Information System (INIS)

    Iwabuchi, A.

    1985-01-01

    The purpose of this work was to investigate the fretting properties of Inconel 625 at high temperature and in high vacuum. Experiments were carried out under constant conditions with a normal load of 14 N and a peak-to-peak slip amplitude of 110 μm and through 6x10 4 cycles. Several environmental conditions were used. Pressure was varied between 10 -3 and 10 5 Pa at temperatures of 20 and 500 0 C. Temperatures up to 500 0 C were also used at pressures of 10 -3 and 10 5 Pa. At 10 -3 Pa and 500 0 C wear loss was negligible but wear scars showed severe damage consisting of deep cracks and accretion of transferred debris. The coefficient of friction then maintained a high value of 1.7 throughout the fretting test. The critical pressure below which oxidation rate becomes reduced is 10 Pa, a value independent of temperature. At pressures below this critical value the coefficient of friction increases steeply and the fretting mechanism changes from one of oxidative wear to one of adhesive wear. A compacted so-called 'glaze' oxide was formed at temperatures above 300 0 C in air (10 5 Pa) and at pressures above 10 3 Pa at 500 0 C. A comparison of results for Inconel 625 with those for S45C and SUS304 steels and Inconel 600 is given. (orig.)

  4. Label free selective detection of estriol using graphene oxide-based fluorescence sensor

    Science.gov (United States)

    Kushwaha, H. S.; Sao, Reshma; Vaish, Rahul

    2014-07-01

    Water-soluble and fluorescent Graphene oxide (GO) is biocompatible, easy, and economical to synthesize. Interestingly, GO is also capable of quenching fluorescence. On the basis of its fluorescence and quenching abilities, GO has been reported to serve as an energy acceptor in a fluorescence resonance energy transfer (FRET) sensor. GO-based FRET biosensors have been widely reported for sensing of proteins, nucleic acid, ATP (Adenosine triphosphate), etc. GO complexes with fluorescent dyes and enzymes have been used to sense metal ions. Graphene derivatives have been used for sensing endocrine-disrupting chemicals like bisphenols and chlorophenols with high sensitivity and good reproducibility. On this basis, a novel GO based fluorescent sensor has been successfully designed to detect estriol with remarkable selectivity and sensitivity. Estriol is one of the three estrogens in women and is considered to be medically important. Estriol content of maternal urine or plasma acts as an important screening marker for estimating foetal growth and development. In addition, estriol is also used as diagnostic marker for diseases like breast cancer, osteoporosis, neurodegenerative and cardiovascular diseases, insulin resistance, lupus erythematosus, endometriosis, etc. In this present study, we report for the first time a rapid, sensitive with detection limit of 1.3 nM, selective and highly biocompatible method for label free detection of estriol under physiological conditions using fluorescence assay.

  5. Error analysis and new dual-cosine window for estimating the sensor frequency response function from the step response data

    Science.gov (United States)

    Yang, Shuang-Long; Liang, Li-Ping; Liu, Hou-De; Xu, Ke-Jun

    2018-03-01

    Aiming at reducing the estimation error of the sensor frequency response function (FRF) estimated by the commonly used window-based spectral estimation method, the error models of interpolation and transient errors are derived in the form of non-parameter models. Accordingly, window effects on the errors are analyzed and reveal that the commonly used hanning window leads to smaller interpolation error which can also be significantly eliminated by the cubic spline interpolation method when estimating the FRF from the step response data, and window with smaller front-end value can restrain more transient error. Thus, a new dual-cosine window with its non-zero discrete Fourier transform bins at -3, -1, 0, 1, and 3 is constructed for FRF estimation. Compared with the hanning window, the new dual-cosine window has the equivalent interpolation error suppression capability and better transient error suppression capability when estimating the FRF from the step response; specifically, it reduces the asymptotic property of the transient error from O(N-2) of the hanning window method to O(N-4) while only increases the uncertainty slightly (about 0.4 dB). Then, one direction of a wind tunnel strain gauge balance which is a high order, small damping, and non-minimum phase system is employed as the example for verifying the new dual-cosine window-based spectral estimation method. The model simulation result shows that the new dual-cosine window method is better than the hanning window method for FRF estimation, and compared with the Gans method and LPM method, it has the advantages of simple computation, less time consumption, and short data requirement; the actual data calculation result of the balance FRF is consistent to the simulation result. Thus, the new dual-cosine window is effective and practical for FRF estimation.

  6. Homo-FRET Imaging as a tool to quantify protein and lipid clustering

    NARCIS (Netherlands)

    Bader, A.N.; Hoetzl, S.; Hofman, E.G.; Voortman, J.; van Bergen en Henegouwen, P.M.P.; van Meer, G.; Gerritsen, H.C.

    2010-01-01

    Homo-FRET, Förster resonance energy transfer between identical fluorophores, can be conveniently measured by observing its effect on the fluorescence anisotropy. This review aims to summarize the possibilities of fluorescence anisotropy imaging techniques to investigate clustering of identical

  7. n+ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC

    Directory of Open Access Journals (Sweden)

    Zhiqiang Zhang

    2017-06-01

    Full Text Available To achieve radio frequency (RF power detection, gain control, and circuit protection, this paper presents n+ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC process. Experiments show that these sensors have reflection losses of less than −17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µV/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µV/mW for the sensor with the thermal slug and the back cavity, respectively.

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

    Science.gov (United States)

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

    2013-11-12

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

  9. Optimizing FRET-FLIM Labeling Conditions to Detect Nuclear Protein Interactions at Native Expression Levels in Living Arabidopsis Roots

    KAUST Repository

    Long, Yuchen

    2018-05-15

    Protein complex formation has been extensively studied using Förster resonance energy transfer (FRET) measured by Fluorescence Lifetime Imaging Microscopy (FLIM). However, implementing this technology to detect protein interactions in living multicellular organism at single-cell resolution and under native condition is still difficult to achieve. Here we describe the optimization of the labeling conditions to detect FRET-FLIM in living plants. This study exemplifies optimization procedure involving the identification of the optimal position for the labels either at the N or C terminal region and the selection of the bright and suitable, fluorescent proteins as donor and acceptor labels for the FRET study. With an effective optimization strategy, we were able to detect the interaction between the stem cell regulators SHORT-ROOT and SCARECROW at endogenous expression levels in the root pole of living Arabidopsis embryos and developing lateral roots by FRET-FLIM. Using this approach we show that the spatial profile of interaction between two transcription factors can be highly modulated in reoccurring and structurally resembling organs, thus providing new information on the dynamic redistribution of nuclear protein complex configurations in different developmental stages. In principle, our optimization procedure for transcription factor complexes is applicable to any biological system.

  10. Fretting wear behavior of zirconium alloy in B-Li water at 300 °C

    Science.gov (United States)

    Zhang, Lefu; Lai, Ping; Liu, Qingdong; Zeng, Qifeng; Lu, Junqiang; Guo, Xianglong

    2018-02-01

    The tangential fretting wear of three kinds of zirconium alloys tube mated with 304 stainless steel (SS) plate was investigated. The tests were conducted in an autoclave containing 300 °C pressurized B-Li water for tube-on-plate contact configuration. The worn surfaces were examined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and 3D microscopy. The cross-section of wear scar was examined with transmission electron microscope (TEM). The results indicated that the dominant wear mechanism of zirconium alloys in this test condition was delamination and oxidation. The oxide layer on the fretted area consists of outer oxide layer composed of iron oxide and zirconium oxide and inner oxide layer composed of zirconium oxide.

  11. Advanced non-linear flow-induced vibration and fretting-wear analysis capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Toorani, M.; Pan, L.; Li, R.; Idvorian, N. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Vincent, B.

    2009-07-01

    Fretting wear is a potentially significant degradation mechanism in nuclear steam generators and other shell and tube heat transfer equipment as well. This paper presents an overview of the recently developed code FIVDYNA which is used for the non-linear flow-induced vibration and fretting wear analysis for operating steam generators (OTSG and RSG) and shell-and-tube heat exchangers. FIVDYNA is a non-linear time-history Flow-Induced Vibration (FIV) analysis computer program that has been developed by Babcock and Wilcox Canada to advance the understanding of tube vibration and tube to tube-support interaction. In addition to the dynamic fluid induced forces the program takes into account other tube static forces due to axial and lateral tube preload and thermal interaction loads. The program is capable of predicting the location where the fretting wear is most likely to occur and its magnitude taking into account the support geometry including gaps. FIVDYNA uses the general purpose finite element computer code ABAQUS as its solver. Using ABAQUS gives the user the flexibility to add additional forces to the tube ranging from tube preloads and the support offsets to thermal loads. The forces currently being modeled in FIVDYNA are the random turbulence, steady drag force, fluid-elastic forces, support offset and pre-strain force (axial loads). This program models the vibration of tubes and calculates the structural dynamic characteristics, and interaction forces between the tube and the tube supports. These interaction forces are then used to calculate the work rate at the support and eventually the predicted depth of wear scar on the tube. A very good agreement is found with experiments and also other computer codes. (author)

  12. Coupled wave sensor technology

    International Nuclear Information System (INIS)

    Maki, M.C.

    1988-01-01

    Buried line guided radar sensors have been used successfully for a number of years to provide perimeter security for high value resources. This paper introduces a new complementary sensor advancement at Computing Devices termed 'coupled wave device technology' (CWD). It provides many of the inherent advantages of leakey cable sensors, such as terrain-following and the ability to discriminate between humans and small animals. It also is able to provide a high or wide detection zone, and allows the sensor to be mounted aerially and adjacent to a wall or fence. Several alternative sensors have been developed which include a single-line sensor, a dual-line hybrid sensor that combines the elements of ported coax and CWD technology, and a rapid-deployment portable sensor for temporary or mobile applications. A description of the technology, the sensors, and their characteristics is provided

  13. A passive UHF RFID tag chip with a dual-resolution temperature sensor in a 0.18 μm standard CMOS process

    International Nuclear Information System (INIS)

    Feng Peng; Zhang Qi; Wu Nanjian

    2011-01-01

    This paper presents a passive EPC Gen-2 UHF RFID tag chip with a dual-resolution temperature sensor. The chip tag integrates a temperature sensor, an RF/analog front-end circuit, an NVM memory and a digital baseband in a standard CMOS process. The sensor with a low power sigma—delta (ΣΔ) ADC is designed to operate in low and high resolution modes. It can not only achieve the target accuracy but also reduce the power consumption and the sensing time. A CMOS-only RF rectifier and a single-poly non-volatile memory (NVM) are designed to realize a low cost tag chip. The 192-bit-NVM tag chip with an area of 1 mm 2 is implemented in a 0.18-μm standard CMOS process. The sensitivity of the tag is −10.7 dBm/−8.4 dBm when the sensor is disabled/enabled. It achieves a maximum reading/sensing distance of 4 m/3.1 m at 2 W EIRP. The inaccuracy of the sensor is −0.6 °C/0.5 °C (−1.0 °C/1.2 °C) in the operating range from 5 to 15 °C in high resolution mode (−30 to 50 °C in low resolution mode). The resolution of the sensor achieves 0.02 °C (0.18 °C) in high (low) resolution mode. (semiconductor integrated circuits)

  14. A Comparative Study on the Formation Mechanism of Wear Scars during the Partial and Full Scale Fretting Wear Tests of Spacer Grids

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Shin, Chang Hwan; Oh, Dong Seok; Kang, Heung Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Fretting wear studies for evaluating the contact damages of nuclear fuel rods have been focused on the contact shape, rod motion, contact condition, environment, etc.. However, fretting wear mechanism was dramatically changed with slight variation of test variables such as test environments and contact shapes. For example, in an unlubricated condition, effects of wear debris and/or its layer on the fretting wear mechanism showed that the formation of a well-developed layer on the contact surfaces has a beneficial effect for decreasing a friction coefficient. Otherwise, a severe wear was happened due to a third body abrasion. In addition, in water lubrication condition, some of wear debris was remained on worn surface of fuel rod specimens at both sliding and impacting loading conditions. So, it is apparent that a wear rate of fuel rod specimen was easily accelerated by the third-body abrasion. This is because the restrained agglomeration behavior between generated wear particles results in rapid removal of wear debris and its layer. In case of contact shape effects, previous studies show that wear debris are easily trapped between contact surfaces and its debris layer was well developed in a localized area especially in a concave spring rather than a convex spring shape. Consequently, localized wear was happened at both ends of a concave spring and center region of a convex spring. So, it is useful for determining the fretting wear resistance of spacer gird spring and dimple by using part unit in the various lubricated conditions. It is well known that the fretting wear phenomenon of nuclear fuel rod is originated from a flow-induced vibration (FIV) due to the rapid primary coolant. This means that both rod vibration and debris removal behavior were affected by flow fields around the contact regions between fuel rod and spring/dimple. However, all most of the fretting tests were performed by simulating rod vibrating motions such as axial vibration, conservative rod

  15. A Comparative Study on the Formation Mechanism of Wear Scars during the Partial and Full Scale Fretting Wear Tests of Spacer Grids

    International Nuclear Information System (INIS)

    Lee, Young Ho; Shin, Chang Hwan; Oh, Dong Seok; Kang, Heung Seok

    2012-01-01

    Fretting wear studies for evaluating the contact damages of nuclear fuel rods have been focused on the contact shape, rod motion, contact condition, environment, etc.. However, fretting wear mechanism was dramatically changed with slight variation of test variables such as test environments and contact shapes. For example, in an unlubricated condition, effects of wear debris and/or its layer on the fretting wear mechanism showed that the formation of a well-developed layer on the contact surfaces has a beneficial effect for decreasing a friction coefficient. Otherwise, a severe wear was happened due to a third body abrasion. In addition, in water lubrication condition, some of wear debris was remained on worn surface of fuel rod specimens at both sliding and impacting loading conditions. So, it is apparent that a wear rate of fuel rod specimen was easily accelerated by the third-body abrasion. This is because the restrained agglomeration behavior between generated wear particles results in rapid removal of wear debris and its layer. In case of contact shape effects, previous studies show that wear debris are easily trapped between contact surfaces and its debris layer was well developed in a localized area especially in a concave spring rather than a convex spring shape. Consequently, localized wear was happened at both ends of a concave spring and center region of a convex spring. So, it is useful for determining the fretting wear resistance of spacer gird spring and dimple by using part unit in the various lubricated conditions. It is well known that the fretting wear phenomenon of nuclear fuel rod is originated from a flow-induced vibration (FIV) due to the rapid primary coolant. This means that both rod vibration and debris removal behavior were affected by flow fields around the contact regions between fuel rod and spring/dimple. However, all most of the fretting tests were performed by simulating rod vibrating motions such as axial vibration, conservative rod

  16. New dual emission fluorescent sensor for pH and Pb(II) based on bis(napfthalimide) derivative

    Energy Technology Data Exchange (ETDEWEB)

    Pina-Luis, Georgina, E-mail: gpinaluis@yahoo.com [Centro de Graduados e Investigacion en Quimica, Instituto Tecnologico de Tijuana, AP 1166, Tijuana 22500, BC (Mexico); Martinez-Quiroz, Marisela; Ochoa-Teran, Adrian [Centro de Graduados e Investigacion en Quimica, Instituto Tecnologico de Tijuana, AP 1166, Tijuana 22500, BC (Mexico); Santacruz-Ortega, Hisila [Departamento de investigacion en Polimeros y Materiales, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); Mendez-Valenzuela, Eduardo [Centro de Graduados e Investigacion en Quimica, Instituto Tecnologico de Tijuana, AP 1166, Tijuana 22500, BC (Mexico)

    2013-02-15

    This paper describes a novel dual emission bis-1,8-naphthalimide sensor for selective determination of pH and Pb{sup 2+} ions. The influence of the variability in the backbone that links the two fluorophores (naphthalimides) as a function of pH and metal ions was studied by UV-visible and fluorescence spectroscopy. Compounds 1(a-d) with different length alkyl linkers (CH{sub 2}){sub n} (n=1, 2, 4 and 6) showed no excimer formation in aqueous solution. Fluorescence emission of these derivatives varied in a narrow range of pH (5-8) and was only slightly influenced by the addition of metal ions in CH{sub 3}CN solutions. However, derivative 1e with amino-containing spacer (CH{sub 2}-NH-CH{sub 2}) showed excimer emission in aqueous solution, a wide response to pH (2.5-9.5) and fluorescence enhancement with selective behavior towards metal ions. The pH sensor based in derivative 1e has a sufficient selectivity for practical pH monitoring in the presence of Li{sup +}, Na{sup +}, K{sup +}, Cs{sup +}, Ca{sup 2+}, Mg{sup 2+}, Ba{sup 2+}, Cu{sup 2+}, Pb{sup 2+}, Ni{sup 2+}, Zn{sup 2+} and Cd{sup 2+}. The coordination chemistry of these complexes was studied by UV-Vis, fluorescence and {sup 1}H NMR. This chemosensor displayed high selectivity fluorescence enhancement toward Pb{sup 2+} ions in the presence of the metals ions mentioned in CH{sub 3}CN solutions. Competitive assays show that a 1-fold of metal cations in each case, compared with Pb{sup 2+} ions, results in less than {+-}5% fluorescence intensity changes. Linear calibration up to 1 Multiplication-Sign 10{sup -5} M for Pb(II) ions (R=0.9968) was obtained and detection limit resulted of 5.0 Multiplication-Sign 10{sup -8} M. - Highlights: Black-Right-Pointing-Pointer A novel dual emission bis-1,8-naphthalimide sensor for pH and Pb{sup 2+} ions is synthetized. Black-Right-Pointing-Pointer The excimer formation depends on the spacer that links the two naphthalimide groups. Black-Right-Pointing-Pointer Bis

  17. Stability Loss of the Cemented Stem of Hip Prosthesis due to Fretting Corrosion Fatigue

    Directory of Open Access Journals (Sweden)

    L. Capitanu

    2017-12-01

    Full Text Available Aim of this project was to study the fretting behaviour of the cemented femoral stem fixation of a total hip prosthesis, trying to capture the loss of contact between the femoral stem and polymetylmethacrilate cement fixation. To have a landmark, studies were performed compared with cementless fixation, where no fretting phenomenon occurs, on real prostheses, under biological 3D loading conditions. A fatigue test device, installed on a servo-hydraulic triaxial dynamic testing machine was used. It allowed monitoring the flexion-extension, abduction-adduction, inner-outer rotation movements, and the variation of the torsional torque, depending on normal loading. The test ends when the sample does not fail after 2000000 cycles, or when it has reached a predetermined number of cycles. Test fluid medium used was NaCl mixed with distilled water, a favourable environment for appearance of fretting corrosion. After the failure of stem fixation at 2450000 cycles, the mantle of bone cement remaining adherent on femoral stem was removed. Microscopic inspection of the femoral stem and of the inner part of the polymetylmethacrilate mantle demonstrated the existence of corrosion of the femoral stem surface beneath the cement mantle, and Fe2O3 deposits on the femoral stem surface and on the inner part of the mantle.

  18. Steady-state acceptor fluorescence anisotropy imaging under evanescent excitation for visualisation of FRET at the plasma membrane.

    Directory of Open Access Journals (Sweden)

    Viviane Devauges

    Full Text Available We present a novel imaging system combining total internal reflection fluorescence (TIRF microscopy with measurement of steady-state acceptor fluorescence anisotropy in order to perform live cell Förster Resonance Energy Transfer (FRET imaging at the plasma membrane. We compare directly the imaging performance of fluorescence anisotropy resolved TIRF with epifluorescence illumination. The use of high numerical aperture objective for TIRF required correction for induced depolarization factors. This arrangement enabled visualisation of conformational changes of a Raichu-Cdc42 FRET biosensor by measurement of intramolecular FRET between eGFP and mRFP1. Higher activity of the probe was found at the cell plasma membrane compared to intracellularly. Imaging fluorescence anisotropy in TIRF allowed clear differentiation of the Raichu-Cdc42 biosensor from negative control mutants. Finally, inhibition of Cdc42 was imaged dynamically in live cells, where we show temporal changes of the activity of the Raichu-Cdc42 biosensor.

  19. Highly sensitive FRET-based fluorescence immunoassay for aflatoxin B1 using cadmium telluride quantum dots

    International Nuclear Information System (INIS)

    Zekavati, Roya; Bayat, Mansour; Safi, Shahabeddin; Hashemi, Seyed Jamal; Rahmani-Cherati, Tavoos; Tabatabaei, Meisam; Mohsenifar, Afshin

    2013-01-01

    We report on a competitive immunoassay for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET) from anti-aflatoxin B1 antibody (immobilized on the shell of CdTe quantum dots) to Rhodamine 123 (Rho 123-labeled aflatoxin B1 bound to albumin). The highly specific immuno reaction between the antibody against aflatoxin B1 on the QDs and the labeled-aflatoxin B1 brings the Rho 123 fluorophore (acting as the acceptor) and the QDs (acting as the donor) in close spatial proximity and causes FRET to occur upon photoexcitation of the QDs. In the absence of unlabeled aflatoxin B1, the antigen-antibody complex is stable, and strong emission resulting from the FRET from QDs to labeled aflatoxin B1 is observed. In the presence of aflatoxin B1, it will compete with the labeled aflatoxin B1-albumin complex for binding to the antibody-QDs conjugate so that FRET will be increasingly suppressed. The reduction in the fluorescence intensity of the acceptor correlates well with the concentration of aflatoxin B1. The feasibility of the method was established by the detection of aflatoxin B1 in spiked human serum. There is a linear relationship between the increased fluorescence intensity of Rho 123 with increasing concentration of aflatoxin B1 in spike human serum, over the range of 0.1–0.6 μmol·mL −1 . The limit of detection is 2 × 10 −11 M. This homogeneous competitive detection scheme is simple, rapid and efficient, and does not require excessive washing and separation steps. (author)

  20. FRET-Aptamer Assays for Bone Marker Assessment, C-Telopeptide, Creatinine, and Vitamin D

    Science.gov (United States)

    Bruno, John G.

    2013-01-01

    Astronauts lose 1.0 to 1.5% of their bone mass per month on long-duration spaceflights. NASA wishes to monitor the bone loss onboard spacecraft to develop nutritional and exercise countermeasures, and make adjustments during long space missions. On Earth, the same technology could be used to monitor osteoporosis and its therapy. Aptamers bind to targets against which they are developed, much like antibodies. However, aptamers do not require animal hosts or cell culture and are therefore easier, faster, and less expensive to produce. In addition, aptamers sometimes exhibit greater affinity and specificity vs. comparable antibodies. In this work, fluorescent dyes and quenchers were added to the aptamers to enable pushbutton, one-step, bind-and-detect fluorescence resonance energy transfer (FRET) assays or tests that can be freeze-dried, rehydrated with body fluids, and used to quantitate bone loss of vitamin D levels with a handheld fluorometer in the spacecraft environment. This work generated specific, rapid, one-step FRET assays for the bone loss marker C-telopeptide (CTx) when extracted from urine, creatinine from urine, and vitamin D congeners in diluted serum. The assays were quantified in nanograms/mL using a handheld fluorometer connected to a laptop computer to convert the raw fluorescence values into concentrations of each analyte according to linear standard curves. DNA aptamers were selected and amplified for several rounds against a 26- amino acid form of CTx, creatinine, and vitamin D. The commonalities between loop structures were studied, and several common loop structures were converted into aptamer beacons with a fluorophore and quencher on each end. In theory, when the aptamer beacon binds its cognate target (CTx bone peptide, creatinine, or vitamin D), it is forced open and no longer quenched, so it gives off fluorescent light (when excited) in proportion to the amount of target present in a sample. This proportional increase in fluorescence is

  1. SH2 Domain-Based FRET Biosensor for Measuring BCR-ABL Activity in Living CML Cells.

    Science.gov (United States)

    Fujioka, Mari; Asano, Yumi; Nakada, Shigeyuki; Ohba, Yusuke

    2017-01-01

    Fluorescent proteins (FPs) displaying distinct spectra have shed their light on a wide range of biological functions. Moreover, sophisticated biosensors engineered to contain single or multiple FPs, including Förster resonance energy transfer (FRET)-based biosensors, spatiotemporally reveal the molecular mechanisms underlying a variety of pathophysiological processes. However, their usefulness for applied life sciences has yet to be fully explored. Recently, our research group has begun to expand the potential of FPs from basic biological research to the clinic. Here, we describe a method to evaluate the responsiveness of leukemia cells from patients to tyrosine kinase inhibitors using a biosensor based on FP technology and the principle of FRET. Upon phosphorylation of the tyrosine residue of the biosensor, binding of the SH2 domain to phosphotyrosine induces conformational change of the biosensor and brings the donor and acceptor FPs into close proximity. Therefore, kinase activity and response to kinase inhibitors can be monitored by an increase and a decrease in FRET efficiency, respectively. As in basic research, this biosensor resolves hitherto arduous tasks and may provide innovative technological advances in clinical laboratory examinations. State-of-the-art detection devices that enable such innovation are also introduced.

  2. Critical Shell Thickness of Core/Shell Upconversion Luminescence Nanoplatform for FRET Application

    NARCIS (Netherlands)

    Wang, Yu; Liu, Kai; Liu, Xiaomin; Dohnalova, Katerina; Gregorkiewicz, Tom; Kong, Xianggui; Aalders, Maurice C. G.; Buma, Wybren J.; Zhang, Hong

    2011-01-01

    Almost all the luminescence upconversion nanoparticles used for Forster resonant energy transfer (FRET) applications are bare cores based on the consideration that the energy transfer efficiency is optimized because the distance between energy donors and acceptors is minimized. On the other hand, it

  3. Determination of Equilibrium Constant and Relative Brightness in FRET-FCS by Including the Third-Order Correlations.

    Science.gov (United States)

    Meng, Lingyi; He, Shanshan; Zhao, Xin Sheng

    2017-12-21

    Fluorescence correlation spectroscopy (FCS) encodes the information on the equilibrium constant (K), the relative fluorescence brightness of fluorophore (Q), and the forward and backward reaction rate constants (k + and k - ) on a physical or chemical relaxation. However, it has been a long-standing problem to completely resolve the FCS data to get the thermodynamic and kinetic information. Recently, we have solved the problem for fluorescence autocorrelation spectroscopy (FACS). Here, we extend the method to fluorescence cross-correlation spectroscopy (FCCS), which appears when FCS is coupled with fluorescence resonance energy transfer (FRET). Among 12 total second-order and third-order pre-exponential factors in a relaxation process probed by the FRET-FCS technique, 3 are independent. We presented and discussed 3 sets of explicit solutions to use these pre-exponential factors to calculate K and Q. Together with the relaxation time, the acquired K will allow people to obtain k + and k - , so that the goal of deciphering the FRET-FCS data will be fully reached. The theory is verified by extensive computer simulations and tested experimentally on a system of oligonucleotide hybridization.

  4. Influence of thermal oxidation duration on the microstructure and fretting wear behavior of Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

    2015-06-01

    Thermal oxidation under water oxidizing atmosphere was performed on Ti6Al4V alloy under different durations from 2 h to 8 h. Surface characterizations were performed using X-ray diffractometery (XRD), scanning electron microscopy (SEM), Raman spectroscopy, nanoindentation and nano scratch testing. Fretting wear behaviors of untreated and oxidized samples were also examined. The formed oxide coating mainly included rutile TiO{sub 2} as well as a little alumina. The weight gain with respect to the oxidation duration obeyed the linear oxidation kinetics law. The growth of oxide grains was in inadequate growth state of incomplete scale coverage from 2nd to 4th hour duration, in normal growth state from 4th to 6th hour duration while in excessive growth state of oxide particle agglomeration and surface roughening from 6th to 8th (or more than 8th) hour duration. The coating thickness increased from 5 μm to 12 μm as oxidation duration increased from 2 h to 8 h. The increase in duration also increased surface roughness and nano hardness as well as adhesion strength of the film/substrate for oxidized samples. The nano hardness value was 10.06 ± 2.15 GPa and the critical load of failure during nano scratch testing was 554.3 ± 6.44 mN for 4 h treated sample. The untreated and oxidized samples showed a same fretting running status and fretting regime with a displacement amplitude of 200 μm while revealing different fretting failure mechanisms. It was mainly abrasive and adhesive wear under ploughing force for untreated sample, while a mix of 3-body abrasion by rolling oxide particles and severe plastic deformation under high contact stress between two ceramic materials for the oxidized samples. The oxide coating was not worn out and improved the fretting wear resistance of titanium alloy. - Highlights: • A thickness of 5–12 μm rutile TiO{sub 2} coating formed under different oxidation durations. • Weight gain with respect to oxidation duration obeyed linear

  5. Revisitation of FRET methods to measure intraprotein distances in Human Serum Albumin

    Energy Technology Data Exchange (ETDEWEB)

    Santini, S.; Bizzarri, A.R.; Cannistraro, S., E-mail: cannistr@unitus.it

    2016-11-15

    We revisited the FRET methods to measure the intraprotein distance between Trp-214 (used as donor) of Human Serum Albumin and its Cys-34, labelled with 1.5-Iaedans (used as acceptor). Variation of Trp fluorescence emission in terms of both intensity and lifetime, as well the enhancement of the acceptor fluorescence emission upon Trp excitation, have been monitored. A careful statistical analysis of the fluorescence results from ten independently prepared samples, combined with suitable spectral corrections, provided reproducible distances estimations by each one of the three methods. Even if monitoring of the donor lifetime variation in the presence of the acceptor reproduces at the best the crystallographic data, by allowing even sub-nanometre distance variations to be appreciated, we suggest that a comparative analysis of all the three methods, applied with statistical significance, should be preferred to achieve a better reliability of the FRET technique.

  6. Uzawa algorithm to solve elastic and elastic-plastic fretting wear problems within the bipotential framework

    Science.gov (United States)

    Ning, Po; Feng, Zhi-Qiang; Quintero, Juan Antonio Rojas; Zhou, Yang-Jing; Peng, Lei

    2018-03-01

    This paper deals with elastic and elastic-plastic fretting problems. The wear gap is taken into account along with the initial contact distance to obtain the Signorini conditions. Both the Signorini conditions and the Coulomb friction laws are written in a compact form. Within the bipotential framework, an augmented Lagrangian method is applied to calculate the contact forces. The Archard wear law is then used to calculate the wear gap at the contact surface. The local fretting problems are solved via the Uzawa algorithm. Numerical examples are performed to show the efficiency and accuracy of the proposed approach. The influence of plasticity has been discussed.

  7. Dichotomy Boundary at Aeolis Mensae, Mars: Fretted Terrain Developed in a Sedimentary Deposit

    Science.gov (United States)

    Irwin, R. P., III; Watters, T. R.; Howard, A. D.; Maxwell, T. A.; Craddock, R. A.

    2003-03-01

    Fretted terrain in Aeolis Mensae, Mars, developed in a sedimentary deposit. A thick, massive unit with a capping layer or duricrust overlies a more durable layered sequence. Wind, collapse, and minor fluvial activity contributed to degradation.

  8. n⁺ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC.

    Science.gov (United States)

    Zhang, Zhiqiang; Liao, Xiaoping

    2017-06-17

    To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n⁺ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than -17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µ V/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µ V/mW for the sensor with the thermal slug and the back cavity, respectively.

  9. A combined experimental and finite element approach to analyse the fretting mechanism of the head-stem taper junction in total hip replacement

    NARCIS (Netherlands)

    Bitter, T.; Khan, I.; Marriott, T.; Lovelady, E.; Verdonschot, N.J.; Janssen, D.W.

    2017-01-01

    Fretting corrosion at the taper interface of modular hip implants has been implicated as a possible cause of implant failure. This study was set up to gain more insight in the taper mechanics that lead to fretting corrosion. The objectives of this study therefore were (1) to select experimental

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

    Directory of Open Access Journals (Sweden)

    Shinwon Kang

    2013-11-01

    Full Text Available 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.

  11. Fast-NPS-A Markov Chain Monte Carlo-based analysis tool to obtain structural information from single-molecule FRET measurements

    Science.gov (United States)

    Eilert, Tobias; Beckers, Maximilian; Drechsler, Florian; Michaelis, Jens

    2017-10-01

    The analysis tool and software package Fast-NPS can be used to analyse smFRET data to obtain quantitative structural information about macromolecules in their natural environment. In the algorithm a Bayesian model gives rise to a multivariate probability distribution describing the uncertainty of the structure determination. Since Fast-NPS aims to be an easy-to-use general-purpose analysis tool for a large variety of smFRET networks, we established an MCMC based sampling engine that approximates the target distribution and requires no parameter specification by the user at all. For an efficient local exploration we automatically adapt the multivariate proposal kernel according to the shape of the target distribution. In order to handle multimodality, the sampler is equipped with a parallel tempering scheme that is fully adaptive with respect to temperature spacing and number of chains. Since the molecular surrounding of a dye molecule affects its spatial mobility and thus the smFRET efficiency, we introduce dye models which can be selected for every dye molecule individually. These models allow the user to represent the smFRET network in great detail leading to an increased localisation precision. Finally, a tool to validate the chosen model combination is provided. Programme Files doi:http://dx.doi.org/10.17632/7ztzj63r68.1 Licencing provisions: Apache-2.0 Programming language: GUI in MATLAB (The MathWorks) and the core sampling engine in C++ Nature of problem: Sampling of highly diverse multivariate probability distributions in order to solve for macromolecular structures from smFRET data. Solution method: MCMC algorithm with fully adaptive proposal kernel and parallel tempering scheme.

  12. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward; van der Werf, Kees; Hollink, Anton; Worhoff, Kerstin; de Ridder, R.M.; Subramaniam, Vinod; Pollnau, Markus

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminium oxide is presented. Single micro-particles with diameters ranging between 1 μm and 20 μm are detected.

  13. Correlative FRET: new method improves rigor and reproducibility in determining distances within synaptic nanoscale architecture

    Science.gov (United States)

    Shinogle-Decker, Heather; Martinez-Rivera, Noraida; O'Brien, John; Powell, Richard D.; Joshi, Vishwas N.; Connell, Samuel; Rosa-Molinar, Eduardo

    2018-02-01

    A new correlative Förster Resonance Energy Transfer (FRET) microscopy method using FluoroNanogold™, a fluorescent immunoprobe with a covalently attached Nanogold® particle (1.4nm Au), overcomes resolution limitations in determining distances within synaptic nanoscale architecture. FRET by acceptor photobleaching has long been used as a method to increase fluorescence resolution. The transfer of energy from a donor to an acceptor generally occurs between 10-100Å, which is the relative distance between the donor molecule and the acceptor molecule. For the correlative FRET microscopy method using FluoroNanogold™, we immuno-labeled GFP-tagged-HeLa-expressing Connexin 35 (Cx35) with anti-GFP and with anti-Cx35/36 antibodies, and then photo-bleached the Cx before processing the sample for electron microscopic imaging. Preliminary studies reveal the use of Alexa Fluor® 594 FluoroNanogold™ slightly increases FRET distance to 70Å, in contrast to the 62.5Å using AlexaFluor 594®. Preliminary studies also show that using a FluoroNanogold™ probe inhibits photobleaching. After one photobleaching session, Alexa Fluor 594® fluorescence dropped to 19% of its original fluorescence; in contrast, after one photobleaching session, Alexa Fluor 594® FluoroNanogold™ fluorescence dropped to 53% of its original intensity. This result confirms that Alexa Fluor 594® FluoroNanogold™ is a much better donor probe than is Alexa Fluor 594®. The new method (a) creates a double confirmation method in determining structure and orientation of synaptic architecture, (b) allows development of a two-dimensional in vitro model to be used for precise testing of multiple parameters, and (c) increases throughput. Future work will include development of FluoroNanogold™ probes with different sizes of gold for additional correlative microscopy studies.

  14. A Study on Corrosion and Fretting Wear Resistance of Alloy 690 Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Won, Ju Jin; Min, Su Jung; Kim, Myeong Su; Kim, Kyu Tae [Dongguk Univ., Gyeongju (Korea, Republic of)

    2013-10-15

    In this article, the effects of such failures have on the materials of alloy 690 are assessed. The corroded volume variation and mass decreased continuously with time. However, the oxide volume changes in an irregular pattern since the oxide formed on the alloy 690 metal may be detached due to the flake formation. The amount of the fretting wear increased with time. It can be seen that the wear rate increased with time and reduced at the later time. The test results show that the ductility decreased as corrosion increases. Alloy 690 is broadly used as a material of nuclear power plant's steam generator tubes because of its excellent mechanical strength, corrosion properties, wear properties and stability at a high temperature. However, the tubes for nuclear power plant's steam generators become a major threat for lifetime management and efficient operation of nuclear power plant due to various corrosion and fretting wear failures caused by flow-induced vibration (FIV) that occurs between tubes.

  15. A dansyl-rhodamine chemosensor for Fe(III) based on off-on FRET

    Science.gov (United States)

    Piao, Jingyu; Lv, Jia; Zhou, Xin; Zhao, Tong; Wu, Xue

    2014-07-01

    A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe3+ based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe3+ to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off-on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job's plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe3+. The association constant was estimated to be 2.72 × 103 M-1 according to the Benesi-Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field.

  16. In vivo imaging of hierarchical spatiotemporal activation of caspase-8 during apoptosis.

    Directory of Open Access Journals (Sweden)

    Katsuya Kominami

    Full Text Available BACKGROUND: Activation of caspases is crucial for the execution of apoptosis. Although the caspase cascade associated with activation of the initiator caspase-8 (CASP8 has been investigated in molecular and biochemical detail, the dynamics of CASP8 activation are not fully understood. METHODOLOGY/PRINCIPAL FINDINGS: We have established a biosensor based on fluorescence resonance energy transfer (FRET for visualizing apoptotic signals associated with CASP8 activation at the single-cell level. Our dual FRET (dual-FRET system, comprising a triple fusion fluorescent protein, enabled us to simultaneously monitor the activation of CASP8 and its downstream effector, caspase-3 (CASP3 in single live cells. With the dual-FRET-based biosensor, we detected distinct activation patterns of CASP8 and CASP3 in response to various apoptotic stimuli in mammalian cells, resulting in the positive feedback amplification of CASP8 activation. We reproduced these observations by in vitro reconstitution of the cascade, with a recombinant protein mixture that included procaspases. Furthermore, using a plasma membrane-bound FRET-based biosensor, we captured the spatiotemporal dynamics of CASP8 activation by the diffusion process, suggesting the focal activation of CASP8 is sufficient to propagate apoptotic signals through death receptors. CONCLUSIONS: Our new FRET-based system visualized the activation process of both initiator and effector caspases in a single apoptotic cell and also elucidated the necessity of an amplification loop for full activation of CASP8.

  17. A Dual Conductance Sensor for Simultaneous Measurement of Void Fraction and Structure Velocity of Downward Two-Phase Flow in a Slightly Inclined Pipe.

    Science.gov (United States)

    Lee, Yeon-Gun; Won, Woo-Youn; Lee, Bo-An; Kim, Sin

    2017-05-08

    In this study, a new and improved electrical conductance sensor is proposed for application not only to a horizontal pipe, but also an inclined one. The conductance sensor was designed to have a dual layer, each consisting of a three-electrode set to obtain two instantaneous conductance signals in turns, so that the area-averaged void fraction and structure velocity could be measured simultaneously. The optimum configuration of the electrodes was determined through numerical analysis, and the calibration curves for stratified and annular flow were obtained through a series of static experiments. The fabricated conductance sensor was applied to a 45 mm inner diameter U-shaped downward inclined pipe with an inclination angle of 3° under adiabatic air-water flow conditions. In the tests, the superficial velocities ranged from 0.1 to 3.0 m/s for water and from 0.1 to 18 m/s for air. The obtained mean void fraction and the structure velocity from the conductance sensor were validated against the measurement by the wire-mesh sensor and the cross-correlation technique for the visualized images, respectively. The results of the flow regime classification and the corresponding time series of the void fraction at a variety of flow velocities were also discussed.

  18. Wide field-of-view dual-band multispectral muzzle flash detection

    Science.gov (United States)

    Montoya, J.; Melchor, J.; Spiliotis, P.; Taplin, L.

    2013-06-01

    Sensor technologies are undergoing revolutionary advances, as seen in the rapid growth of multispectral methodologies. Increases in spatial, spectral, and temporal resolution, and in breadth of spectral coverage, render feasible sensors that function with unprecedented performance. A system was developed that addresses many of the key hardware requirements for a practical dual-band multispectral acquisition system, including wide field of view and spectral/temporal shift between dual bands. The system was designed using a novel dichroic beam splitter and dual band-pass filter configuration that creates two side-by-side images of a scene on a single sensor. A high-speed CMOS sensor was used to simultaneously capture data from the entire scene in both spectral bands using a short focal-length lens that provided a wide field-of-view. The beam-splitter components were arranged such that the two images were maintained in optical alignment and real-time intra-band processing could be carried out using only simple arithmetic on the image halves. An experiment related to limitations of the system to address multispectral detection requirements was performed. This characterized the system's low spectral variation across its wide field of view. This paper provides lessons learned on the general limitation of key hardware components required for multispectral muzzle flash detection, using the system as a hardware example combined with simulated multispectral muzzle flash and background signatures.

  19. Elimination of ghost markers during dual sensor-based infrared tracking of multiple individual reflective markers

    International Nuclear Information System (INIS)

    Stroian, G.; Falco, T.; Seuntjens, J.P.

    2004-01-01

    The accuracy of dose delivery in radiotherapy is affected by the uncertainty in tumor localization. Motion of internal anatomy due to physiological processes such as respiration may lead to significant displacements which compromise tumor coverage and generate irradiation of healthy tissue. Real-time tracking with infrared-based systems is often used for tracking thoracic motion in radiation therapy. We studied the origin of ghost markers ('crosstalk') which may appear during dual sensor-based infrared tracking of independent reflective markers. Ghost markers occur when two or more reflective markers are coplanar with each other and with the sensors of the two camera-based infrared tracking system. Analysis shows that sensors are not points but they have a finite extent and this extent determines for each marker a 'ghost volume'. If one reflective marker enters the ghost volume of another marker, ghost markers will be reported by the tracking system; if the reflective markers belong to a surface their 'ghost volume' is reduced to a 'ghost surface' (ghost zone). Appearance of ghost markers is predicted for markers taped on the torso of an anthropomorphic phantom. This study illustrates the dependence of the shape, extent, and location of the ghost zones on the shape of the anthropomorphic phantom, the angle of view of the tracking system, and the distance between the tracking system and the anthropomorphic phantom. It is concluded that the appearance of ghost markers can be avoided by positioning the markers outside the ghost zones of the other markers. However, if this is not possible and the initial marker configuration is ghost marker-free, ghost markers can be eliminated during real-time tracking by virtue of the fact that they appear in the coordinate data sequence only temporarily

  20. Probing the Conformational Landscape of DNA Polymerases Using Diffusion-Based Single-Molecule FRET

    NARCIS (Netherlands)

    Hohlbein, J.; Kapanidis, A.N.

    2016-01-01

    Monitoring conformational changes in DNA polymerases using single-molecule Förster resonance energy transfer (smFRET) has provided new tools for studying fidelity-related mechanisms that promote the rejection of incorrect nucleotides before DNA synthesis. In addition to the previously known open

  1. Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

    Energy Technology Data Exchange (ETDEWEB)

    Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Dong-Ho [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Hak Ju [Division of Green Business Management, Department of Forest Resources Utilization, Korean Forest Research Institute, Seoul 130-712 (Korea, Republic of); Lee, Chul; Lee, Myung Koo [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Hwang, Bang Yeon, E-mail: byhwang@chungbuk.ac.kr [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Sung-Joon, E-mail: junelee@korea.ac.kr [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)

    2013-01-25

    Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARα and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages.

  2. Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

    International Nuclear Information System (INIS)

    Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin; Lee, Dong-Ho; Lee, Hak Ju; Lee, Chul; Lee, Myung Koo; Hwang, Bang Yeon; Lee, Sung-Joon

    2013-01-01

    Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARα and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages

  3. The Use of Two-Photon FRET-FLIM to Study Protein Interactions During Nuclear Envelope Fusion In Vivo and In Vitro.

    Science.gov (United States)

    Byrne, Richard D; Larijani, Banafshé; Poccia, Dominic L

    2016-01-01

    FRET-FLIM techniques have wide application in the study of protein and protein-lipid interactions in cells. We have pioneered an imaging platform for accurate detection of functional states of proteins and their interactions in fixed cells. This platform, two-site-amplified Förster resonance energy transfer (a-FRET), allows greater signal generation while retaining minimal noise thus enabling application of fluorescence lifetime imaging microscopy (FLIM) to be routinely deployed in different types of cells and tissue. We have used the method described here, time-resolved FRET monitored by two-photon FLIM, to demonstrate the direct interaction of Phospholipase Cγ (PLCγ) by Src Family Kinase 1 (SFK1) during nuclear envelope formation and during male and female pronuclear membrane fusion in fertilized sea urchin eggs. We describe here a generic method that can be applied to monitor any proteins of interest.

  4. Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

    International Nuclear Information System (INIS)

    Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam

    2014-01-01

    The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines

  5. Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

    Energy Technology Data Exchange (ETDEWEB)

    Sadasivuni, Kishor Kumar, E-mail: kishor_kumars@yahoo.com [Centre for Advanced Materials, Qatar University, Doha (Qatar); Ponnamma, Deepalekshmi [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam [Centre for Advanced Materials, Qatar University, Doha (Qatar)

    2014-10-15

    The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines.

  6. Electrophoresis- and FRET-Based Measures of Serpin Polymerization.

    Science.gov (United States)

    Faull, Sarah V; Brown, Anwen E; Haq, Imran; Irving, James A

    2017-01-01

    Many serpinopathies, including alpha-1 antitrypsin (A1AT) deficiency, are associated with the formation of unbranched polymer chains of mutant serpins. In vivo, this deficiency is the result of mutations that cause kinetic or thermodynamic destabilization of the molecule. However, polymerization can also be induced in vitro from mutant or wild-type serpins under destabilizing conditions. The characteristics of the resulting polymers are dependent upon induction conditions. Due to their relationship to disease, serpin polymers, mainly those formed from A1AT, have been widely studied. Here, we describe Förster resonance energy transfer (FRET) and gel-based approaches for their characterization.

  7. Effects of Plasma ZrN Metallurgy and Shot Peening Duplex Treatment on Fretting Wear and Fretting Fatigue Behavior of Ti6Al4V Alloy.

    Science.gov (United States)

    Tang, Jingang; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing; Yu, Shouming

    2016-03-23

    A metallurgical zirconium nitride (ZrN) layer was fabricated using glow metallurgy using nitriding with zirconiuming prior treatment of the Ti6Al4V alloy. The microstructure, composition and microhardness of the corresponding layer were studied. The influence of this treatment on fretting wear (FW) and fretting fatigue (FF) behavior of the Ti6Al4V alloy was studied. The composite layer consisted of an 8-μm-thick ZrN compound layer and a 50-μm-thick nitrogen-rich Zr-Ti solid solution layer. The surface microhardness of the composite layer is 1775 HK 0.1 . A gradient in cross-sectional microhardness distribution exists in the layer. The plasma ZrN metallurgical layer improves the FW resistance of the Ti6Al4V alloy, but reduces the base FF resistance. This occurs because the improvement in surface hardness results in lowering of the toughness and increasing in the notch sensitivity. Compared with shot peening treatment, plasma ZrN metallurgy and shot peening composite treatment improves the FW resistance and enhances the FF resistance of the Ti6Al4V alloy. This is attributed to the introduction of a compressive stress field. The combination of toughness, strength, FW resistance and fatigue resistance enhance the FF resistance for titanium alloy.

  8. Experimental Simulation of Flow-Induced Vibration for Developing a Grid-to-Rod Fretting Model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngho; Kim, Hyungkyu; Kang, Heungseok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    GTRF margin was calculated based on the fuel reliabilities program of operating power plants. But they have not accumulated sufficient experience under challenging operating conditions to be considered proven solutions. In addition, GTRF behaviors were significantly differed according to the plant types, operating condition and fuel types. So, analytical methods to resolve GTRF degradations are considered as difficult procedures for actual application. One of the most important problems is that it is difficult to evaluate the GTRF resistance of new spacer grid under operating power plant condition. Up to now, as a consequence, compliance with the fretting wear limit (typically 10% of the cladding thickness) is checked a posteriori, through post-irradiation examination. Therefore, in this study, rod simulation method for determining GTRF resistance of new spacer grid was proposed with a specially designed wear tester. This simulator enables us to examine the spacer grid shape effect under relatively short development period. In addition, for developing GTRF model, flow-induced vibration (FIV) was measured with different major variables such as GTR clearance, flow rate, etc. Fretting wear tests of nuclear fuel rods (i. e. grid-to-rod fretting) have been performed to examine the flow rate effect by using a specially designed test section with a simulated primary coolant. Based on above results, developed FIV-wear simulator could be effective to examine the spacer grid shape effect with short development period. Further study will be discussed on the GTR clearance effect with various spacer grid shapes.

  9. Genetically encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics.

    Science.gov (United States)

    Baker, Bradley J; Jin, Lei; Han, Zhou; Cohen, Lawrence B; Popovic, Marko; Platisa, Jelena; Pieribone, Vincent

    2012-07-15

    A substantial increase in the speed of the optical response of genetically encoded fluorescent protein voltage sensors (FP voltage sensors) was achieved by using the voltage-sensing phosphatase genes of Nematostella vectensis and Danio rerio. A potential N. vectensis voltage-sensing phosphatase was identified in silico. The voltage-sensing domain (S1-S4) of the N. vectensis homolog was used to create an FP voltage sensor called Nema. By replacing the phosphatase with a cerulean/citrine FRET pair, a new FP voltage sensor was synthesized with fast off kinetics (Tau(off)voltage-sensing phosphatase homolog, designated Zahra and Zahra 2, exhibited fast on and off kinetics within 2ms of the time constants observed with the organic voltage-sensitive dye, di4-ANEPPS. Mutagenesis of the S4 region of the Danio FP voltage sensor shifted the voltage dependence to more negative potentials but did not noticeably affect the kinetics of the optical signal. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Genetically-encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics

    Science.gov (United States)

    Baker, Bradley J.; Jin, Lei; Han, Zhou; Cohen, Lawrence B.; Popovic, Marko; Platisa, Jelena; Pieribone, Vincent

    2012-01-01

    A substantial increase in the speed of the optical response of genetically-encoded Fluorescent Protein voltage sensors (FP voltage sensors) was achieved by using the voltage-sensing phosphatase genes of Nematostella vectensis and Danio rerio. A potential N. vectensis voltage-sensing phosphatase was identified in silico. The voltage-sensing domain (S1–S4) of the N. vectensis homolog was used to create an FP voltage sensor called Nema. By replacing the phosphatase with a cerulean/citrine FRET pair, a new FP voltage sensor was synthesized with fast off kinetics (Tauoff voltage-sensing phosphatase homolog, designated Zahra and Zahra 2, exhibited fast on and off kinetics within 2 msec of the time constants observed with the organic voltage-sensitive dye, di4-ANEPPS. Mutagenesis of the S4 region of the Danio FP voltage sensor shifted the voltage dependence to more negative potentials but did not noticeably affect the kinetics of the optical signal. PMID:22634212

  11. Tumor specific lung cancer diagnostics with multiplexed FRET immunoassays

    Science.gov (United States)

    Geißler, D.; Hill, D.; Löhmannsröben, H.-G.; Thomas, E.; Lavigne, A.; Darbouret, B.; Bois, E.; Charbonnière, L. J.; Ziessel, R. F.; Hildebrandt, N.

    2010-02-01

    An optical multiplexed homogeneous (liquid phase) immunoassay based on FRET from a terbium complex to eight different fluorescent dyes is presented. We achieved highly sensitive parallel detection of four different lung cancer specific tumor markers (CEA, NSE, SCC and CYFRA21-1) within a single assay and show a proof-of-principle for 5- fold multiplexing. The method is well suited for fast and low-cost miniaturized point-of-care testing as well as for highthroughput screening in a broad range of in-vitro diagnostic applications.

  12. Semiconductor quantum dots as Förster resonance energy transfer donors for intracellularly-based biosensors

    Science.gov (United States)

    Field, Lauren D.; Walper, Scott A.; Susumu, Kimihiro; Oh, Eunkeu; Medintz, Igor L.; Delehanty, James B.

    2017-02-01

    Förster resonance energy transfer (FRET)-based assemblies currently comprise a significant portion of intracellularly based sensors. Although extremely useful, the fluorescent protein pairs typically utilized in such sensors are still plagued by many photophysical issues including significant direct acceptor excitation, small changes in FRET efficiency, and limited photostability. Luminescent semiconductor nanocrystals or quantum dots (QDs) are characterized by many unique optical properties including size-tunable photoluminescence, broad excitation profiles coupled to narrow emission profiles, and resistance to photobleaching, which can cumulatively overcome many of the issues associated with use of fluorescent protein FRET donors. Utilizing QDs for intracellular FRET-based sensing still requires significant development in many areas including materials optimization, bioconjugation, cellular delivery and assay design and implementation. We are currently developing several QD-based FRET sensors for various intracellular applications. These include sensors targeting intracellular proteolytic activity along with those based on theranostic nanodevices for monitoring drug release. The protease sensor is based on a unique design where an intracellularly expressed fluorescent acceptor protein substrate assembles onto a QD donor following microinjection, forming an active complex that can be monitored in live cells over time. In the theranostic configuration, the QD is conjugated to a carrier protein-drug analogue complex to visualize real-time intracellular release of the drug from its carrier in response to an external stimulus. The focus of this talk will be on the design, properties, photophysical characterization and cellular application of these sensor constructs.

  13. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward H.; van der Werf, Kees O; Hollink, Anton J F; Worhoff, Kerstin; De Ridder, Rene M.; Subramaniam, Vinod; Pollnau, Markus

    2013-01-01

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in Al2O3:Yb3+ is presented. Real-time detection and accurate size measurement of single microparticles with diameters ranging between 1 μm and 20 μm are

  14. A dansyl-rhodamine chemosensor for Fe(III) based on off-on FRET.

    Science.gov (United States)

    Piao, Jingyu; Lv, Jia; Zhou, Xin; Zhao, Tong; Wu, Xue

    2014-07-15

    A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe(3+) based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe(3+) to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off-on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job's plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe(3+). The association constant was estimated to be 2.72×10(3) M(-1) according to the Benesi-Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. A wireless sensor enabled by wireless power.

    Science.gov (United States)

    Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

    2012-11-22

    Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

  16. Sensor Fusion Based on an Integrated Neural Network and Probability Density Function (PDF) Dual Kalman Filter for On-Line Estimation of Vehicle Parameters and States.

    Science.gov (United States)

    Vargas-Melendez, Leandro; Boada, Beatriz L; Boada, Maria Jesus L; Gauchia, Antonio; Diaz, Vicente

    2017-04-29

    Vehicles with a high center of gravity (COG), such as light trucks and heavy vehicles, are prone to rollover. This kind of accident causes nearly 33 % of all deaths from passenger vehicle crashes. Nowadays, these vehicles are incorporating roll stability control (RSC) systems to improve their safety. Most of the RSC systems require the vehicle roll angle as a known input variable to predict the lateral load transfer. The vehicle roll angle can be directly measured by a dual antenna global positioning system (GPS), but it is expensive. For this reason, it is important to estimate the vehicle roll angle from sensors installed onboard in current vehicles. On the other hand, the knowledge of the vehicle's parameters values is essential to obtain an accurate vehicle response. Some of vehicle parameters cannot be easily obtained and they can vary over time. In this paper, an algorithm for the simultaneous on-line estimation of vehicle's roll angle and parameters is proposed. This algorithm uses a probability density function (PDF)-based truncation method in combination with a dual Kalman filter (DKF), to guarantee that both vehicle's states and parameters are within bounds that have a physical meaning, using the information obtained from sensors mounted on vehicles. Experimental results show the effectiveness of the proposed algorithm.

  17. Development of Hardware Dual Modality Tomography System

    Directory of Open Access Journals (Sweden)

    R. M. Zain

    2009-06-01

    Full Text Available The paper describes the hardware development and performance of the Dual Modality Tomography (DMT system. DMT consists of optical and capacitance sensors. The optical sensors consist of 16 LEDs and 16 photodiodes. The Electrical Capacitance Tomography (ECT electrode design use eight electrode plates as the detecting sensor. The digital timing and the control unit have been developing in order to control the light projection of optical emitters, switching the capacitance electrodes and to synchronize the operation of data acquisition. As a result, the developed system is able to provide a maximum 529 set data per second received from the signal conditioning circuit to the computer.

  18. Intramolecular ex vivo Fluorescence Resonance Energy Transfer (FRET of Dihydropyridine Receptor (DHPR β1a Subunit Reveals Conformational Change Induced by RYR1 in Mouse Skeletal Myotubes.

    Directory of Open Access Journals (Sweden)

    Dipankar Bhattacharya

    Full Text Available The dihydropyridine receptor (DHPR β1a subunit is essential for skeletal muscle excitation-contraction coupling, but the structural organization of β1a as part of the macromolecular DHPR-ryanodine receptor type I (RyR1 complex is still debatable. We used fluorescence resonance energy transfer (FRET to probe proximity relationships within the β1a subunit in cultured skeletal myotubes lacking or expressing RyR1. The fluorescein biarsenical reagent FlAsH was used as the FRET acceptor, which exhibits fluorescence upon binding to specific tetracysteine motifs, and enhanced cyan fluorescent protein (CFP was used as the FRET donor. Ten β1a reporter constructs were generated by inserting the CCPGCC FlAsH binding motif into five positions probing the five domains of β1a with either carboxyl or amino terminal fused CFP. FRET efficiency was largest when CCPGCC was positioned next to CFP, and significant intramolecular FRET was observed for all constructs suggesting that in situ the β1a subunit has a relatively compact conformation in which the carboxyl and amino termini are not extended. Comparison of the FRET efficiency in wild type to that in dyspedic (lacking RyR1 myotubes revealed that in only one construct (H458 CCPGCC β1a -CFP FRET efficiency was specifically altered by the presence of RyR1. The present study reveals that the C-terminal of the β1a subunit changes conformation in the presence of RyR1 consistent with an interaction between the C-terminal of β1a and RyR1 in resting myotubes.

  19. Ratiometric detection of pH fluctuation in mitochondria with a new fluorescein/cyanine hybrid sensor.

    Science.gov (United States)

    Chen, Yuncong; Zhu, Chengcheng; Cen, Jiajie; Bai, Yang; He, Weijiang; Guo, Zijian

    2015-05-01

    The homeostasis of mitochondrial pH (pH m ) is crucial in cell physiology. Developing small-molecular fluorescent sensors for the ratiometric detection of pH m fluctuation is highly demanded yet challenging. A ratiometric pH sensor, Mito-pH , was constructed by integrating a pH-sensitive FITC fluorophore with a pH-insensitive hemicyanine group. The hemicyanine group also acts as the mitochondria targeting group due to its lipophilic cationic nature. Besides its ability to target mitochondria, this sensor provides two ratiometric pH sensing modes, the dual excitation/dual emission mode (D ex /D em ) and dual excitation (D ex ) mode, and its linear and reversible ratiometric response range from pH 6.15 to 8.38 makes this sensor suitable for the practical tracking of pH m fluctuation in live cells. With this sensor, stimulated pH m fluctuation has been successfully tracked in a ratiometric manner via both fluorescence imaging and flow cytometry.

  20. A fluorescence resonance energy transfer (FRET) biosensor based on graphene quantum dots (GQDs) and gold nanoparticles (AuNPs) for the detection of mecA gene sequence of Staphylococcus aureus.

    Science.gov (United States)

    Shi, Jingyu; Chan, Chunyu; Pang, Yukting; Ye, Weiwei; Tian, Feng; Lyu, Jing; Zhang, Yu; Yang, Mo

    2015-05-15

    In this work, a novel fluorescence resonance energy transfer (FRET) biosensor based on graphene quantum dots (GQDs) and gold nanoparticles (AuNPs) pairs was developed for Staphylococcus aureus specific gene sequence detection. This FRET biosensor platform was realized by immobilization of capture probes on GQDs and conjugation of reporter probes on AuNPs. Target oligos then co-hybridized with capture probes and reporter probes to form a sandwich structure which brought GQDs and AuNPs to close proximity to trigger FRET effect. The fluorescence signals before and after addition of targets were measured and the fluorescence quenching efficiency could reach around 87% with 100 nM target oligo. The limit of detection (LOD) of this FRET biosensor was around 1 nM for S.aureus gene detection. Experiments with both single-base mismatched oligos and double-base mismatched oligos demonstrated the good sequence selectivity of this FRET biosensor. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Lifetime-based optical sensor for high-level pCO2 detection employing fluorescence resonance energy transfer

    International Nuclear Information System (INIS)

    Bueltzingsloewen, Christoph von; McEvoy, Aisling K.; McDonagh, Colette; MacCraith, Brian D.

    2003-01-01

    An optical sensor for the measurement of high levels of carbon dioxide in gas phase has been developed. It is based on fluorescence resonance energy transfer (FRET) between a long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye are both immobilised in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix material. Tetraoctylammonium hydroxide (TOA-OH) is used as an internal buffering system. Fluorescence lifetime is measured in the frequency domain, using low-cost phase modulation measurement technology. The use of Sudan III as an acceptor dye has enabled the sensor to have a dynamic range up to 100% carbon dioxide. The sensor displays 11.2 deg. phase shift between the limit of detection (LOD) of 0.06 and 100% CO 2 with a resolution of better than 2%. The encapsulation in the silica/polymer hybrid material has provided the sensor with good mechanical and chemical stability. The effect of molecular oxygen, humidity and temperature on the sensor performance was studied in detail

  2. Fretting wear of ZrN and Zr(21% Hf)N coatings

    Energy Technology Data Exchange (ETDEWEB)

    Atar, E. [Gebze Inst. of Tech., Material Science and Engineering Dept., Kocaeli (Turkey); Cimenoglu, H.; Kayali, E.S. [Istanbul Technical Univ., Dept. of Metallurgy and Materials Engineering, Istanbul (Turkey)

    2004-07-01

    In this study, the wear behaviours of ZrN and Zr(21% Hf)N coatings, deposited on hardened AISI D2 cold work tool steel were examined by a fretting wear tester. The hardness of ZrN and Zr(21% Hf)N coatings were almost the same, where as they exhibited different wear resistance. Addition of 21% Hf to ZrN coating achieved about 25% increase in the wear resistance. (orig.)

  3. Fretting wear of ZrN and Zr(21% Hf)N coatings

    International Nuclear Information System (INIS)

    Atar, E.; Cimenoglu, H.; Kayali, E.S.

    2004-01-01

    In this study, the wear behaviours of ZrN and Zr(21% Hf)N coatings, deposited on hardened AISI D2 cold work tool steel were examined by a fretting wear tester. The hardness of ZrN and Zr(21% Hf)N coatings were almost the same, where as they exhibited different wear resistance. Addition of 21% Hf to ZrN coating achieved about 25% increase in the wear resistance. (orig.)

  4. Covalent Organic Framework Functionalized with 8-Hydroxyquinoline as a Dual-Mode Fluorescent and Colorimetric pH Sensor.

    Science.gov (United States)

    Chen, Long; He, Linwei; Ma, Fuyin; Liu, Wei; Wang, Yaxing; Silver, Mark A; Chen, Lanhua; Zhu, Lin; Gui, Daxiang; Diwu, Juan; Chai, Zhifang; Wang, Shuao

    2018-05-09

    Real-time and accurate detection of pH in aqueous solution is of great significance in chemical, environmental, and engineering-related fields. We report here the use of 8-hydroxyquinoline-functionalized covalent organic framework (COF-HQ) for dual-mode pH sensing. In the fluorescent mode, the emission intensity of COF-HQ weakened as the pH decreased, and also displayed a good linear relationship against pH in the range from 1 to 5. In addition, COF-HQ showed discernible color changes from yellow to black as the acidity increased and can be therefore used as a colorimetric pH sensor. All these changes are reversible and COF-HQ can be recycled for multiple detection runs owing to its high hydrolytical stability. It can be further assembled into a mixed matrix membrane for practical applications.

  5. Real-time determination of intracellular oxygen in bacteria using a genetically encoded FRET-based biosensor

    Directory of Open Access Journals (Sweden)

    Potzkei Janko

    2012-03-01

    Full Text Available Abstract Background Molecular oxygen (O2 is one of the key metabolites of all obligate and facultative aerobic pro- and eukaryotes. It plays a fundamental role in energy homeostasis whereas oxygen deprivation, in turn, broadly affects various physiological and pathophysiological processes. Therefore, real-time monitoring of cellular oxygen levels is basically a prerequisite for the analysis of hypoxia-induced processes in living cells and tissues. Results We developed a genetically encoded Förster resonance energy transfer (FRET-based biosensor allowing the observation of changing molecular oxygen concentrations inside living cells. This biosensor named FluBO (fluorescent protein-based biosensor for oxygen consists of the yellow fluorescent protein (YFP that is sensitive towards oxygen depletion and the hypoxia-tolerant flavin-binding fluorescent protein (FbFP. Since O2 is essential for the formation of the YFP chromophore, efficient FRET from the FbFP donor domain to the YFP acceptor domain only occurs in the presence but not in the absence of oxygen. The oxygen biosensor was used for continuous real-time monitoring of temporal changes of O2 levels in the cytoplasm of Escherichia coli cells during batch cultivation. Conclusions FluBO represents a unique FRET-based oxygen biosensor which allows the non-invasive ratiometric readout of cellular oxygen. Thus, FluBO can serve as a novel and powerful probe for investigating the occurrence of hypoxia and its effects on a variety of (pathophysiological processes in living cells.

  6. Fretting-wear damage of heat exchanger tubes: a proposed damage criterion based on tube vibration response

    International Nuclear Information System (INIS)

    Yetisir, M.; McKerrow, E.; Pettigrew, M.J.

    1997-01-01

    A simple criterion is proposed to estimate fretting-wear damage in heat exchanger tubes with clearance supports. The criterion is based on parameters such as vibration frequency, mid-span vibration amplitude, span length, tube mass and an empirical wear coefficient. It is generally accepted that fretting-wear damage is proportional to a parameter called work-rate. Work-rate is a measure of the dynamic interaction between a vibrating tube and its supports. Due to the complexity of the impact-sliding behavior at the clearance-supports, work-rate calculations for heat exchanger tubes require specialized non-linear finite element codes. These codes include contact models for various clearance-support geometries. Such non-linear finite element analyses are complex, expensive and time consuming. The proposed criterion uses the results of linear vibration analysis (i.e., vibration frequency and mid-span vibration amplitude due to turbulence) and does not require a non-linear analysis. It can be used by non-specialists for a quick evaluation of the expected work-rate, and hence, the fretting-wear damage of heat exchanger tubes. The proposed criterion was obtained from an extensive parametric study that was conducted using a non-linear finite element program. It is shown that, by using the proposed work-rate criteria, work-rate can be estimated within a factor of two. This result, however, requires further testing with more complicated flow patterns. (author)

  7. A combined experimental and finite element approach to analyse the fretting mechanism of the head-stem taper junction in total hip replacement.

    Science.gov (United States)

    Bitter, Thom; Khan, Imran; Marriott, Tim; Lovelady, Elaine; Verdonschot, Nico; Janssen, Dennis

    2017-09-01

    Fretting corrosion at the taper interface of modular hip implants has been implicated as a possible cause of implant failure. This study was set up to gain more insight in the taper mechanics that lead to fretting corrosion. The objectives of this study therefore were (1) to select experimental loading conditions to reproduce clinically relevant fretting corrosion features observed in retrieved components, (2) to develop a finite element model consistent with the fretting experiments and (3) to apply more complicated loading conditions of activities of daily living to the finite element model to study the taper mechanics. The experiments showed similar wear patterns on the taper surface as observed in retrievals. The finite element wear score based on Archard's law did not correlate well with the amount of material loss measured in the experiments. However, similar patterns were observed between the simulated micromotions and the experimental wear measurements. Although the finite element model could not be validated, the loading conditions based on activities of daily living demonstrate the importance of assembly load on the wear potential. These findings suggest that finite element models that do not incorporate geometry updates to account for wear loss may not be appropriate to predict wear volumes of taper connections.

  8. FRET-based localization of fluorescent protein insertions within the ryanodine receptor type 1.

    Directory of Open Access Journals (Sweden)

    Shweta A Raina

    Full Text Available Fluorescent protein (FP insertions have often been used to localize primary structure elements in mid-resolution 3D cryo electron microscopic (EM maps of large protein complexes. However, little is known as to the precise spatial relationship between the location of the fused FP and its insertion site within a larger protein. To gain insights into these structural considerations, Förster resonance energy transfer (FRET measurements were used to localize green fluorescent protein (GFP insertions within the ryanodine receptor type 1 (RyR1, a large intracellular Ca(2+ release channel that plays a key role in skeletal muscle excitation contraction coupling. A series of full-length His-tagged GFP-RyR1 fusion constructs were created, expressed in human embryonic kidney (HEK-293T cells and then complexed with Cy3NTA, a His-tag specific FRET acceptor. FRET efficiency values measured from each GFP donor to Cy3NTA bound to each His tag acceptor site were converted into intermolecular distances and the positions of each inserted GFP were then triangulated relative to a previously published X-ray crystal structure of a 559 amino acid RyR1 fragment. We observed that the chromophoric centers of fluorescent proteins inserted into RyR1 can be located as far as 45 Å from their insertion sites and that the fused proteins can also be located in internal cavities within RyR1. These findings should prove useful in interpreting structural results obtained in cryo EM maps using fusions of small fluorescent proteins. More accurate point-to-point distance information may be obtained using complementary orthogonal labeling systems that rely on fluorescent probes that bind directly to amino acid side chains.

  9. Maximum likelihood-based analysis of photon arrival trajectories in single-molecule FRET

    Energy Technology Data Exchange (ETDEWEB)

    Waligorska, Marta [Adam Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan (Poland); Molski, Andrzej, E-mail: amolski@amu.edu.pl [Adam Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan (Poland)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer We study model selection and parameter recovery from single-molecule FRET experiments. Black-Right-Pointing-Pointer We examine the maximum likelihood-based analysis of two-color photon trajectories. Black-Right-Pointing-Pointer The number of observed photons determines the performance of the method. Black-Right-Pointing-Pointer For long trajectories, one can extract mean dwell times that are comparable to inter-photon times. -- Abstract: When two fluorophores (donor and acceptor) are attached to an immobilized biomolecule, anti-correlated fluctuations of the donor and acceptor fluorescence caused by Foerster resonance energy transfer (FRET) report on the conformational kinetics of the molecule. Here we assess the maximum likelihood-based analysis of donor and acceptor photon arrival trajectories as a method for extracting the conformational kinetics. Using computer generated data we quantify the accuracy and precision of parameter estimates and the efficiency of the Akaike information criterion (AIC) and the Bayesian information criterion (BIC) in selecting the true kinetic model. We find that the number of observed photons is the key parameter determining parameter estimation and model selection. For long trajectories, one can extract mean dwell times that are comparable to inter-photon times.

  10. Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

    Science.gov (United States)

    Lan, Linxin; Li, Tianduo; Wei, Tao; Pang, He; Sun, Tao; Wang, Enhua; Liu, Haixia; Niu, Qingfen

    2018-03-01

    An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN- on the vinyl Cdbnd C bond has been successfully confirmed by the optical measurements, 1H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19 μM, which is much lower than the maximum permission concentration in drinking water (1.9 μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN- in field measurements.

  11. Prévision de l'épaisseur du film passif d'un acier inoxydable 316L soumis au fretting corrosion grâce au Point Defect Model, PDM Predicting the steady state thickness of passive films with the Point Defect Model in fretting corrosion experiments

    Directory of Open Access Journals (Sweden)

    Geringer Jean

    2013-11-01

    Full Text Available Les implants orthopédiques de hanche ont une durée de vie d'environ 15 ans. Par exemple, la tige fémorale d'un tel implant peut être réalisée en acier inoxydable 316L ou 316LN. Le fretting corrosion, frottement sous petits déplacements, peut se produire pendant la marche humaine en raison des chargements répétés entre le métal de la prothèse et l'os. Plusieurs investigations expérimentales du fretting corrosion ont été entreprises. Cette couche passive de quelques nanomètres, à température ambiante, est le point clef sur lequel repose le développement de notre civilisation, selon certains auteurs. Ce travail vise à prédire les épaisseurs de cette couche passive de l'acier inoxydable soumis au fretting corrosion, avec une attention spécifique sur le rôle des protéines. Le modèle utilisé est basé sur le Point Defect Model, PDM (à une échelle microscopique et une amélioration de ce modèle en prenant en compte le processus de frottement sous petits débattements. L'algorithme génétique a été utilisé pour optimiser la convergence du problème. Les résultats les plus importants sont, comme démontré avec les essais expérimentaux, que l'albumine, la protéine étudiée, empêche les dégradations de l'acier inoxydable aux plus faibles concentrations d'ions chlorure ; ensuite, aux plus fortes concentrations de chlorures, un temps d'incubation est nécessaire pour détruire le film passif. Some implants have approximately a lifetime of 15 years. The femoral stem, for example, should be made of 316L/316LN stainless steel. Fretting corrosion, friction under small displacements, should occur during human gait, due to repeated loadings and un-loadings, between stainless steel and bone for instance. Some experimental investigations of fretting corrosion have been practiced. As well known, metallic alloys and especially stainless steels are covered with a passive film that prevents from the corrosion and degradation

  12. Unlubricated Gross Slip Fretting Wear of Metallic Plasma Sprayed Coatings for Ti6A14V Surfaces

    National Research Council Canada - National Science Library

    Hager, Jr., Carl H; Sanders, Jeffrey H; Sharma, Shashi K

    2006-01-01

    ... to simulate cold engine startup. Alternative coatings such as plasma sprayed molybdenum and nickel were also evaluated because of their potential for reducing fretting wear under certain simulated engine conditions...

  13. Zirconia-based solid state chemical gas sensors

    CERN Document Server

    Zhuiykov, S

    2000-01-01

    This paper presents an overview of chemical gas sensors, based on solid state technology, that are sensitive to environmental gases, such as O sub 2 , SO sub x , NO sub x , CO sub 2 and hydrocarbons. The paper is focussed on performance of electrochemical gas sensors that are based on zirconia as a solid electrolyte. The paper considers sensor structures and selection of electrode materials. Impact of interfaces on sensor performance is discussed. This paper also provides a brief overview of electrochemical properties of zirconia and their effect on sensor performance. Impact of auxiliary materials on sensors performance characteristics, such as sensitivity, selectivity, response time and recovery time, is also discussed. Dual gas sensors that can be applied for simultaneous monitoring of the concentration of both oxygen and other gas phase components, are briefly considered

  14. Towards understanding the E. coli PNP binding mechanism and FRET absence between E. coli PNP and formycin A.

    Science.gov (United States)

    Prokopowicz, Małgorzata; Greń, Bartosz; Cieśla, Joanna; Kierdaszuk, Borys

    2017-11-01

    The aim of this study is threefold: (1) augmentation of the knowledge of the E. coli PNP binding mechanism; (2) explanation of the previously observed 'lack of FRET' phenomenon and (3) an introduction of the correction (modified method) for FRET efficiency calculation in the PNP-FA complexes. We present fluorescence studies of the two E. coli PNP mutants (F159Y and F159A) with formycin A (FA), that indicate that the aromatic amino acid is indispensable in the nucleotide binding, additional hydroxyl group at position 159 probably enhances the strength of binding and that the amino acids pair 159-160 has a great impact on the spectroscopic properties of the enzyme. The experiments were carried out in hepes and phosphate buffers, at pH7 and 8.3. Two methods, a conventional and a modified one, that utilizes the dissociation constant, for calculations of the energy transfer efficiency (E) and the acceptor-to-donor distance (r) between FA and the Tyr (energy donor) were employed. Total difference spectra were calculated for emission spectra (λ ex 280nm, 295nm, 305nm and 313nm) for all studied systems. Time-resolved techniques allowed to conclude the existence of a specific structure formed by amino acids at positions 159 and 160. The results showed an unexpected pattern change of FRET in the mutants, when compared to the wild type enzyme and a probable presence of a structure created between 159 and 160 residue, that might influence the binding efficiency. Additionally, we confirmed the indispensable role of the modification of the FRET efficiency (E) calculation on the fraction of enzyme saturation in PNP-FA systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Highly Sensitive DNA Sensor Based on Upconversion Nanoparticles and Graphene Oxide.

    Science.gov (United States)

    Alonso-Cristobal, P; Vilela, P; El-Sagheer, A; Lopez-Cabarcos, E; Brown, T; Muskens, O L; Rubio-Retama, J; Kanaras, A G

    2015-06-17

    In this work we demonstrate a DNA biosensor based on fluorescence resonance energy transfer (FRET) between NaYF4:Yb,Er nanoparticles and graphene oxide (GO). Monodisperse NaYF4:Yb,Er nanoparticles with a mean diameter of 29.1 ± 2.2 nm were synthesized and coated with a SiO2 shell of 11 nm, which allowed the attachment of single strands of DNA. When these DNA-functionalized NaYF4:Yb,Er@SiO2 nanoparticles were in the proximity of the GO surface, the π-π stacking interaction between the nucleobases of the DNA and the sp(2) carbons of the GO induced a FRET fluorescence quenching due to the overlap of the fluorescence emission of the NaYF4:Yb,Er@SiO2 and the absorption spectrum of GO. By contrast, in the presence of the complementary DNA strands, the hybridization leads to double-stranded DNA that does not interact with the GO surface, and thus the NaYF4:Yb,Er@SiO2 nanoparticles remain unquenched and fluorescent. The high sensitivity and specificity of this sensor introduces a new method for the detection of DNA with a detection limit of 5 pM.

  16. The spatiotemporal pattern of Src activation at lipid rafts revealed by diffusion-corrected FRET imaging.

    Directory of Open Access Journals (Sweden)

    Shaoying Lu

    2008-07-01

    Full Text Available Genetically encoded biosensors based on fluorescence resonance energy transfer (FRET have been widely applied to visualize the molecular activity in live cells with high spatiotemporal resolution. However, the rapid diffusion of biosensor proteins hinders a precise reconstruction of the actual molecular activation map. Based on fluorescence recovery after photobleaching (FRAP experiments, we have developed a finite element (FE method to analyze, simulate, and subtract the diffusion effect of mobile biosensors. This method has been applied to analyze the mobility of Src FRET biosensors engineered to reside at different subcompartments in live cells. The results indicate that the Src biosensor located in the cytoplasm moves 4-8 folds faster (0.93+/-0.06 microm(2/sec than those anchored on different compartments in plasma membrane (at lipid raft: 0.11+/-0.01 microm(2/sec and outside: 0.18+/-0.02 microm(2/sec. The mobility of biosensor at lipid rafts is slower than that outside of lipid rafts and is dominated by two-dimensional diffusion. When this diffusion effect was subtracted from the FRET ratio images, high Src activity at lipid rafts was observed at clustered regions proximal to the cell periphery, which remained relatively stationary upon epidermal growth factor (EGF stimulation. This result suggests that EGF induced a Src activation at lipid rafts with well-coordinated spatiotemporal patterns. Our FE-based method also provides an integrated platform of image analysis for studying molecular mobility and reconstructing the spatiotemporal activation maps of signaling molecules in live cells.

  17. Fretting and wear behaviors of Ni/nano-WC composite coatings in dry and wet conditions

    International Nuclear Information System (INIS)

    Benea, Lidia; Başa, Sorin-Bogdan; Dănăilă, Eliza; Caron, Nadège; Raquet, Olivier; Ponthiaux, Pierre; Celis, Jean-Pierre

    2015-01-01

    Highlights: • The friction and wear properties of Ni/nano-WC composite were studied. • Nano-WC reinforcement decreased friction coefficient in dry and wet conditions. • Nano-WC reinforcement fraction was seen to be 12 wt.%. • Nanohardness increased by 27% compared to nickel without WC reinforcements. • Ennoblement of OCP corresponding to the Ni/nano-WC composite coating. - Abstract: The fretting and wear behaviors of Ni/nano-WC composite coatings were studied by considering the effect of fretting frequency of 1 Hz during 10,000 cycles, at different applied loads in dry or wet conditions. The studies were performed on a ball-on-disk tribometer and the results were compared with pure Ni coating. The nanohardness of pure Ni and Ni/nano-WC composite coatings was tested by nanoindentation technique. To evaluate the wet wear (tribocorrosion) behavior the open circuit potential (OCP) was measured before, during and after the fretting tests at room temperature in the solution that simulates the primary water circuit of Pressurized Water Reactors (PWRs). The results show that Ni/nano-WC composite coatings exhibited a low friction coefficient, high nanohardness and wear resistance compared with pure Ni coatings under similar experimental conditions. Ni/nano-WC composite coatings were obtained on stainless steel support by electrochemical codeposition of nano-sized WC particles (diameter size of ∼60 nm) with nickel, from a standard nickel Watts plating bath. The surface morphology and the composition of the coatings were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) respectively

  18. Wireless interrogation of passive antenna sensors

    International Nuclear Information System (INIS)

    Deshmukh, S; Huang, H

    2010-01-01

    Recently, we discovered that the resonant frequency of a microstrip patch antenna is sensitive to mechanical strains or crack presence in the ground plane. Based on this principle, antenna sensors have been demonstrated to measure strain and detect crack in metallic structures. This paper presents a wireless method to remotely interrogate a dual-frequency antenna sensor. An interrogation horn antenna was used to irradiate the antenna sensor with a linear chirp microwave signal. By implementing a light-activated switch at the sensor node and performing signal processing of the backscattered signals, the resonant frequencies of the antenna sensor along both polarizations can be measured remotely. Since the antenna sensor does not need a local power source and can be interrogated wirelessly, electric wiring can be eliminated. The sensor implementation, the signal processing and the experimental setup that validate the remote interrogation of the antenna sensor are presented. A power budget model has also been established to estimate the maximum interrogation range

  19. Structural changes in the cytoplasmic pore of the Kir1.1 channel during pHi-gating probed by FRET.

    Science.gov (United States)

    Lee, Jay-Ron; Shieh, Ru-Chi

    2009-03-06

    Kir1.1 channels are important in maintaining K+ homeostasis in the kidney. Intracellular acidification reversibly closes the Kir1.1 channel and thus decreases K+ secretion. In this study, we used Foster resonance energy transfer (FRET) to determine whether the conformation of the cytoplasmic pore changes in response to intracellular pH (pHi)-gating in Kir1.1 channels fused with enhanced cyan fluorescent protein (ECFP) and enhanced yellow fluorescent protein (EYFP) (ECFP-Kir1.1-EYFP). Because the fluorescence intensities of ECFP and EYFP were affected at pHi pHi-gating occurs in the ECFP-Kir1.1-EYFP construct, we examined the FRET efficiencies of an ECFP-S219R-EYFP mutant, which is completed closed at pHi 7.4 and open at pHi 10.0. FRET efficiency was increased from 25% to 40% when the pHi was decreased from 10.0 to 7.4. These results suggest that the conformation of the cytoplasmic pore in the Kir1.1 channel changes in response to pHi gating such that the N- and C-termini move apart from each other at pHi 7.4, when the channel is open.

  20. Spectroscopic and theoretical investigation of conformational changes of proteins by synthesized pyrimidine derivative and its sensitivity towards FRET application

    Science.gov (United States)

    Ghosh, Swadesh; Singharoy, Dipti; Bhattacharya, Subhash Chandra

    2018-04-01

    Interest in synthesizing and characterizing (IR, NMR and HRMS spectroscopic methods) a pyrimidine based Schiff-base ligand, 2-(2-(Anthracen-9-ylmethylene) hydrazinyl)-4,6-dimethyl pyrimidine (ANHP) has been developed for its application to ascertain the conformational change of protein and sensitivity towards fluorescence resonance energy transfer (FRET) process. Location of ANHP in bovine serum albumin (BSA) and human serum albumin (HSA) proteins environment has been determined using different spectroscopic techniques. Weakly fluorescent ANHP have shown greater protein induced fluorescence enhancement (PIFE) in case of HSA than BSA, though in both cases energy transfer efficiency are almost same but difference in binding constant values encourages us to find the location of ANHP within the complex protein environment. From the FRET parameter and α-helicity change, it has been found that ANHP bound with Trp-214 of HSA and surface Trp-134 of BSA. Conformational changes of proteins have been observed more for HSA than BSA in presence of ANHP, which has confirmed the location of ANHP in both the protein environments. Coupled with experimental studies, molecular docking analysis has also been done to explain the locations and distance dependent FRET process of ANHP in both proteins.

  1. Dual-sensing porphyrin-containing copolymer nanosensor as full-spectrum colorimeter and ultra-sensitive thermometer.

    Science.gov (United States)

    Yan, Qiang; Yuan, Jinying; Kang, Yan; Cai, Zhinan; Zhou, Lilin; Yin, Yingwu

    2010-04-28

    A porphyrin-containing copolymer has dual-sensing in response to metal ions and temperature as a novel nanosensor. Triggered by ions, the sensor exhibits full-color tunable behavior as a cationic detector and colorimeter. Responding to temperature, the sensor displays an "isothermal" thermochromic point as an ultra-sensitive thermometer.

  2. A Study for Optimum Survey Method of Underwater Structure Using the Dual Sonar Sensor

    Directory of Open Access Journals (Sweden)

    Youngseok Kim

    2017-01-01

    Full Text Available We have developed dual sonar equipment and an improved operating method for improving resolution in order to solve the problems of limitations of the optical equipment and the application method of SSS (side scan sonar in the investigation of damage of underwater structures. We analyzed the influence factors of the resolution of sonar data through the comparison of resolution and data quality in indoor test. Also we confirmed the problems about the overlapping area of the dual sonar. Depth and distance were analyzed as major influencing factors for survey angle. Specimens were scanned while adjusting distance and towfish angle according to depth change in order to verify applicability of the developed dual sonar in the field experiment. Optimal resolution was found to be 3 cm in specimen spacing, and 20 sample data items were extracted. We developed the regression model based on the multiple regression analysis and developed the RealDualSONAR-DAQ tool, the dual sonar optimum operating method program based on proposed correlation equations. We can use the developed tools to get the value of the major influencing factors for dual sonar operation and obtain high quality sonar data to analyze damage of underwater structures.

  3. Effect of different atmospheres on the electrical contact performance of electronic components under fretting wear

    Science.gov (United States)

    Liu, Xin-Long; Cai, Zhen-Bing; Cui, Ye; Liu, Shan-Bang; Xu, Xiao-Jun; Zhu, Min-Hao

    2018-04-01

    The effects of oxide etch on the surface morphology of metals for industrial application is a common cause of electrical contacts failure, and it has becomes a more severe problem with the miniaturization of modern electronic devices. This study investigated the effects of electrical contact resistance on the contactor under three different atmospheres (oxygen, air, and nitrogen) based on 99.9% copper/pogo pins contacts through fretting experiments. The results showed the minimum and stable electrical contact resistance value when shrouded in the nitrogen environment and with high friction coefficient. The rich oxygen environment promotes the formation of cuprous oxide, thereby the electrical contact resistance increases. Scanning electron microscope microscopy and electron probe microanalysis were used to analyze the morphology and distribution of elements of the wear area, respectively. The surface product between contacts was investigated by x-ray photoelectron spectroscopy analysis to explain the different electrical contact properties of the three tested samples during fretting.

  4. Probing plasma membrane microdomains in cowpea protoplasts using lipidated GFP-fusion proteins and multimode FRET microscopy

    NARCIS (Netherlands)

    Vermeer, J.E.M.; van Munster, E.B.; Vischer, N.O.; Gadella, T.

    2004-01-01

    Multimode fluorescence resonance energy transfer (FRET) microscopy was applied to study the plasma membrane organization using different lipidated green fluorescent protein (GFP)-fusion proteins co-expressed in cowpea protoplasts. Cyan fluorescent protein (CFP) was fused to the hyper variable region

  5. Imaging molecular interactions in cells by dynamic and static fluorescence anisotropy (rFLIM and emFRET)

    NARCIS (Netherlands)

    Lidke, D.S.; Nagy, P.; Barisas, B.G.; Heintzmann, R.; Post, Janine Nicole; Lidke, K.A.; Clayton, A.H.A.; Arndt-jovin, D.J.; Jovin, T.M.

    2003-01-01

    We report the implementation and exploitation of fluorescence polarization measurements, in the form of anisotropy fluorescence lifetime imaging microscopy (rFLIM) and energy migration Förster resonance energy transfer (emFRET) modalities, for wide-field, confocal laser-scanning microscopy and flow

  6. Evaluation of a FRET-peptide substrate to predict virulence in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Wendy E Kaman

    Full Text Available Pseudomonas aeruginosa produces a number of proteases that are associated with virulence and disease progression. A substrate able to detect P. aeruginosa-specific proteolytic activity could help to rapidly alert clinicians to the virulence potential of individual P. aeruginosa strains. For this purpose we designed a set of P. aeruginosa-specific fluorogenic substrates, comprising fluorescence resonance energy transfer (FRET-labeled peptides, and evaluated their applicability to P. aeruginosa virulence in a range of clinical isolates. A FRET-peptide comprising three glycines (3xGly was found to be specific for the detection of P. aeruginosa proteases. Further screening of 97 P. aeruginosa clinical isolates showed a wide variation in 3xGly cleavage activity. The absence of 3xGly degradation by a lasI knock out strain indicated that 3xGly cleavage by P. aeruginosa could be quorum sensing (QS-related, a hypothesis strengthened by the observation of a strong correlation between 3xGly cleavage, LasA staphylolytic activity and pyocyanin production. Additionally, isolates able to cleave 3xGly were more susceptible to the QS inhibiting antibiotic azithromycin (AZM. In conclusion, we designed and evaluated a 3xGly substrate possibly useful as a simple tool to predict virulence and AZM susceptibility.

  7. Investigation of fretting corrosion of vacuum-chrome-plated vt3-1 titanium alloy in pair with unprotected vt3-1 alloy and 40khnma steel

    International Nuclear Information System (INIS)

    Rojkh, I.L.; Koltunova, L.N.; Vejtsman, M.G.; Birman, Ya.N.; Skosarev, A.V.; Kogan, I.S.

    1978-01-01

    The character of destruction of contacting surfaces in the process of fretting corrosion of titanium alloy VT3-1 chromized in vacuum in pair with unprotected alloy VT3-1 and steel 40KhNMA has been studied by scanning electron microscopy, electronography, and recording the surface profile. The specific load was 200 kg/cm 2 , vibration amplitude 50 mkm and frequency 500 Hz. It has been established that pairs unprotected with coating are subjected to intensive fretting corrosion especially when they are made of titanium alloy. For the pair chromized alloy VT3-1 - unprotected alloy VT3-1 no destruction of a chromized surface is observed. Vacuum chromium coating in the pair with steel 40KhNMA reveals similar properties as in pair with a titanium alloy. The surface of a steel sample is destroyed because of fretting corrosion, though the intensity of corrosion is lower than in the case of unprotected pairs. Vacuum chromium coating is recommended for protection of titanium alloy VT3-1 from fretting corrosion in pair with steel 40KhNMA or an alloy VT3-1 especially in those cases when various organic coatings are unsuitable

  8. Assessment of Corrosion, Fretting, and Material Loss of Retrieved Modular Total Knee Arthroplasties.

    Science.gov (United States)

    Martin, Audrey J; Seagers, Kirsten A; Van Citters, Douglas W

    2017-07-01

    Modular junctions in total hip arthroplasties have been associated with fretting, corrosion, and debris release. The purpose of this study is to analyze damage severity in total knee arthroplasties of a single design by qualitative visual assessment and quantitative material loss measurements to evaluate implant performance and patient impact via material loss. Twenty-two modular knee retrievals of the same manufacturer were identified from an institutional review board-approved database. Junction designs included tapers with an axial screw and tapers with a radial screw. Constructs consisted of 2 metal alloys: CoCr and Ti6Al4V. Components were qualitatively scored and quantitatively measured for corrosion and fretting. Negative values represent adhered material. Statistical differences were analyzed using sign tests. Correlations were tested with a Spearman rank order test (P corrosion than other components, suggesting preferential corrosion when interfacing with Ti6Al4V. Overall, although corrosion was noted in this series, material loss was low, and none were revised for clinical metal-related reaction. This suggests the clinical impact from corrosion in total knee arthroplasty is low. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. FRET Response of a Modified Ribose Receptor Expressed in the Diatom Thalassiosira pseudonana

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Hanna

    2011-08-26

    The ability to insert complex proteins into silica has many applications including biosensing. Previous research has demonstrated how to direct proteins to the biosilica of diatoms [1]. Here, we show that a complex fusion protein that includes an enzyme, a bacterial ribose periplasmic binding protein, flanked by fluorescent proteins constituting a FRET pair can remain functional in the frustules of living diatoms. A Sil3 tag is attached to the N-terminal end to localize the fusion protein to frustules of the diatom Thalassiosira pseudonana. When ribose was applied, a larger decrease in FRET response was seen in transformed cells than in untransformed cells. Multiple forms of the expression vector were tested to find the optimal system; specifically, a one-vector system was compared to a two-vector system and the gDNA version of the Sil3 localization tag was compared to the cDNA version. The optimal system was found to be a one-vector system with the genomic version of the Sil3 tag to direct the protein to the frustules. Localization of the enzyme to the frustules was further confirmed through cell fluorescence imaging.

  10. Advances in SAW gas sensors based on the condensate-adsorption effect.

    Science.gov (United States)

    Liu, Jiuling; Wang, Wen; Li, Shunzhou; Liu, Minghua; He, Shitang

    2011-01-01

    A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg.

  11. Evaluation of dual-tip micromanometers during 21-day implantation in goats

    Science.gov (United States)

    Reister, C. A.; Koenig, S. C.; Schaub, J. D.; Ewert, D. L.; Swope, R. D.; Latham, R. D.; Fanton, J. W.; Convertino, V. A. (Principal Investigator)

    1998-01-01

    Investigative research efforts using a cardiovascular model required the determination of central circulatory haemodynamic and arterial system parameters for the evaluation of cardiovascular performance. These calculations required continuous beat-to-beat measurement of pressure within the four chambers of the heart and great vessels. Sensitivity and offset drift, longevity, and sources of error for eight 3F dual-tipped micromanometers were determined during 21 days of implantation in goats. Subjects were instrumented with pairs of chronically implanted fluid-filled access catheters in the left and right ventricles, through which dual-tipped (test) micromanometers were chronically inserted and single-tip (standard) micromanometers were acutely inserted. Acutely inserted sensors were calibrated daily and measured pressures were compared in vivo to the chronically inserted sensors. Comparison of the pre- and post-gain calibration of the chronically inserted sensors showed a mean sensitivity drift of 1.0 +/- 0.4% (99% confidence, n = 9 sensors) and mean offset drift of 5.0 +/- 1.5 mmHg (99% confidence, n = 9 sensors). Potential sources of error for these drifts were identified, and included measurement system inaccuracies, temperature drift, hydrostatic column gradients, and dynamic pressure changes. Based upon these findings, we determined that these micromanometers may be chronically inserted in high-pressure chambers for up to 17 days with an acceptable error, but should be limited to acute (hours) insertions in low-pressure applications.

  12. The dual cycle bridge detection of piezoresistive triaxial accelerometer based on MEMS technology

    International Nuclear Information System (INIS)

    Zhang Juanting; He Changde; Zhang Hui; Li Yuping; Du Chunhui; Zhang Wendong; Zhang Yongping

    2014-01-01

    A cycle bridge detection method, which uses a piezoresistive triaxial accelerometer, has been described innovatively. This method just uses eight resistors to form a cycle detection bridge, which can detect the signal of the three directions for real time. It breaks the law of the ordinary independent Wheatstone bridge detection method, which uses at least 12 resistors and each four resistors connected as a Wheatstone bridge to detect the output signal from a specific direction. In order to verify the feasibility of this method, the modeling and simulating of the sensor structure have been conducted by ANSYS, then the dual cycle bridge detection method and independent Wheatstone bridge detection method are compared, the result shows that the former method can improve the sensitivity of the sensor effectively. The sensitivity of the x, y-axis used in the former method is two times that of the sensor used in the latter method, and the sensitivity of the z-axis is four times. At the same time, it can also reduce the cross-axis coupling degree of the sensor used in the dual cycle bridge detection method. In addition, a signal amplifier circuit and adder circuit have been provided. Finally, the test result of the “eight-beams/mass” triaxial accelerometer, which is based on the dual cycle bridge detection method and the related circuits, have been provided. The results of the test and the theoretical analysis are consistent, on the whole. (semiconductor devices)

  13. Optimizing FRET-FLIM Labeling Conditions to Detect Nuclear Protein Interactions at Native Expression Levels in Living Arabidopsis Roots

    KAUST Repository

    Long, Yuchen; Stahl, Yvonne; Weidtkamp-Peters, Stefanie; Smet, Wouter; Du, Yujuan; Gadella, Theodorus W. J.; Goedhart, Joachim; Scheres, Ben; Blilou, Ikram

    2018-01-01

    Protein complex formation has been extensively studied using Förster resonance energy transfer (FRET) measured by Fluorescence Lifetime Imaging Microscopy (FLIM). However, implementing this technology to detect protein interactions in living

  14. A FRET-based approach for quantitative evaluation of forskolin-induced pendrin trafficking at the plasma membrane in bronchial NCI H292 cells.

    Science.gov (United States)

    Tamma, Grazia; Ranieri, Marianna; Dossena, Silvia; Di Mise, Annarita; Nofziger, Charity; Svelto, Maria; Paulmichl, Markus; Valenti, Giovanna

    2013-01-01

    Human pendrin (SLC26A4, PDS) is an integral membrane protein acting as an electroneutral anion exchanger. Loss of function mutations in pendrin protein cause Pendred syndrome, a disorder characterized by sensorineural deafness and a partial iodide organification defect that may lead to thyroid goiter. Additionally, pendrin up-regulation could play a role in the pathogenesis of several diseases including bronchial asthma and chronic obstructive pulmonary disease (COPD). Therefore, monitoring the plasma membrane abundance and trafficking of pendrin in the context of a living cell is crucially important. Trafficking of pendrin to the plasma membrane was monitored by fluorescence resonance energy transfer (FRET), a physical phenomenon occurring between two fluorophores (the FRET donor and acceptor) located in close spatial proximity. Because the efficiency of the energy transfer is inversely proportional to the sixth power of the distance between donor and acceptor, FRET is extremely sensitive to small changes in distance between the donor and acceptor and is therefore a powerful tool to determine protein-protein interactions. FRET studies revealed that forskolin-induced cAMP production is associated with a significant increase of pendrin expression at plasma membrane, which is paralleled by a decrease in intracellular pH. Pendrin transposition to the membrane is accompanied with a partial depolymerization of actin cytoskeleton via Rho-GTPase inhibition. Trafficking to the plasma membrane is critical in the regulation of pendrin activity. Therefore, reliable tools for monitoring and quantifying this phenomenon are highly desirable. © 2014 S. Karger AG, Basel.

  15. Förster resonance energy transfer: Role of diffusion of fluorophore orientation and separation in observed shifts of FRET efficiency.

    Directory of Open Access Journals (Sweden)

    Bram Wallace

    Full Text Available Förster resonance energy transfer (FRET is a widely used single-molecule technique for measuring nanoscale distances from changes in the non-radiative transfer of energy between donor and acceptor fluorophores. For macromolecules and complexes this observed transfer efficiency is used to infer changes in molecular conformation under differing experimental conditions. However, sometimes shifts are observed in the FRET efficiency even when there is strong experimental evidence that the molecular conformational state is unchanged. We investigate ways in which such discrepancies can arise from kinetic effects. We show that significant shifts can arise from the interplay between excitation kinetics, orientation diffusion of fluorophores, separation diffusion of fluorophores, and non-emitting quenching.

  16. Investigation on ionic states of 1,2-Dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) using organic laser dyes: A FRET study

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Arpan Datta; Saha, Jaba; Dey, D.; Bhattacharjee, D.; Hussain, Syed Arshad, E-mail: sa_h153@hotmail.com

    2017-05-15

    Fluorescence Resonance Energy Transfer (FRET) between two organic dyes Fluorescein and Rhodamine 6G were successfully investigated in aqueous solution in presence and absence of 1,2-Dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) at different pH. Spectroscopic studies suggest that both the dyes were present mainly as monomer in solution. FRET occurred from Fluorescein to Rhodamine 6G in solutions. Energy transfer efficiency increases in presence of DPPC and the maximum efficiency was 59.3% when the concentration of DPPC was 1.4×10{sup −4} M at ambient condition. pH plays a crucial role in this investigation as the energy transfer efficiency was found to change in presence of DPPC at different pH. It has been demonstrated that with proper calibration it is possible to use the present system under investigation to realize various ionic states of DPPC by observing the change in FRET efficiency between these two dyes. - Graphical abstract: Electrostatic interaction between anionic Flu and cationic R6G molecules in presence and absence of DPPC at different pH. Here pH of DPPC was changed, not the pH of individual dyes.

  17. Micro-structured optical fiber sensor for simultaneous measurement of temperature and refractive index

    Science.gov (United States)

    Liu, Ying-gang; Liu, Xin; Ma, Cheng-ju; Zhou, Yu-min

    2018-03-01

    Through using micro-machining method for optical fiber sensor, a kind of miniature, compact and composite structural all-fiber sensor is presented. Based on manufacturing two micro-holes with certain distance in ordinary single-mode fiber Bragg grating (FBG) by excimer laser processing technique, we fabricate a dual Fabry-Perot-FBG (FP-FBG) composite fiber interferometric sensor, which can be used in simultaneous measurement for liquid's refractive index (RI) and temperature change. Due to every micro-hole and the dual micro-holes in fiber acting as different Fabry-Perot (FP) cavities, this kind of sensor has not only different RI sensitivities but also different temperature sensitivities, which are corresponding to the wavelength shifts of the fine interference fringes and spectral envelope, respectively. The experimental results show that the spectral wavelength shift keep better linear response for temperature and RI change, so that we can select the higher temperature and RI sensitivities as well as the analyzed sensitivities of FBG to utilize them for constituting a sensitivity coefficients matrix. Finally, the variations of liquid's temperature and RI are detected effectively, and the resolutions can reach to 0.1 °C and 1.0 ×10-5 RIU. These characteristics are what other single-type sensors don't have, so that this kind of all-fiber dual FP-FBG composite fiber interferometric sensor can be used in extremely tiny liquid environment for measuring different physical quantities simultaneously.

  18. A Dual-Core System Solution for Wearable Health Monitors

    NARCIS (Netherlands)

    Santana Arnaiz, O.A.; Bouwens, F.; Huisken, J.A.; De Groot, H.; Bennebroek, M.T.; Van Meerbergen, J.L.; Abbo, A.A.; Fraboulet, A.

    2011-01-01

    This paper presents a system design study for wearable sensor devices intended for healthcare and lifestyle applications based on ECG,EEG and activity monitoring. In order to meet the low-power requirement of these applications, a dual-core signal processing system is proposed which combines an

  19. Development of a pan-Babesia FRET-qPCR and a survey of livestock from five Caribbean islands.

    Science.gov (United States)

    Li, Jing; Kelly, Patrick; Zhang, Jilei; Xu, Chuanling; Wang, Chengming

    2015-09-30

    Babesia spp. are tick-borne protozoan hemoparasites and the second most common blood-borne parasites of mammals, in particular domestic animals. We used the Clustal Multiple Alignment program and 18S rRNA gene sequences of 22 Babesia species from GenBank to develop a PCR that could detect a wide variety of Babesia spp. in a single reaction. The pan-Babesia FRET-qPCR we developed reliably detected B. gibsoni, B. canis, B. vogeli, B. microti, B. bovis, and B. divergens under controlled conditions but did not react with closely related species, mainly Hepatozoon americanum, Theileria equi, and Toxoplasma gondii. When we tested the pan-Babesia FRET-qPCR on DNA of whole blood from 752 cattle, sheep, goats, donkeys and horses from five Caribbean islands, we detected Babesia spp. expected to be present in the animals, mainly B. bovis and B. bigemina in cattle and B. caballi in horses and donkeys. Further, we found that animals were not uncommonly infected with species of Babesia usually associated with other hosts, mainly B. vogeli and B. gibsoni in cattle, sheep and goats, B. rossi in goats, and B. caballi in goats and sheep. Finally, the pan-Babesia FRET-qPCR enabled us to identify unknown species of Babesia in cattle, goats, sheep and donkeys. Overall, 70 % (525/752) of the animals we tested were positive confirming earlier limited studies that infections with Babesia spp. are common in livestock in the Caribbean.

  20. Characterization of a spectrally diverse set of fluorescent proteins as FRET acceptors for mTurquoise2

    NARCIS (Netherlands)

    Mastop, M.; Bindels, D.S.; Shaner, N.C.; Postma, M.; Gadella, T.W.J.; Goedhart, J.

    2017-01-01

    The performance of Förster Resonance Energy Transfer (FRET) biosensors depends on brightness and photostability, which are dependent on the characteristics of the fluorescent proteins that are employed. Yellow fluorescent protein (YFP) is often used as an acceptor but YFP is prone to photobleaching

  1. Inter-Dye Distance Distributions Studied by a Combination of Single-Molecule FRET-Filtered Lifetime Measurements and a Weighted Accessible Volume (wAV Algorithm

    Directory of Open Access Journals (Sweden)

    Henning Höfig

    2014-11-01

    Full Text Available Förster resonance energy transfer (FRET is an important tool for studying the structural and dynamical properties of biomolecules. The fact that both the internal dynamics of the biomolecule and the movements of the biomolecule-attached dyes can occur on similar timescales of nanoseconds is an inherent problem in FRET studies. By performing single-molecule FRET-filtered lifetime measurements, we are able to characterize the amplitude of the motions of fluorescent probes attached to double-stranded DNA standards by means of flexible linkers. With respect to previously proposed experimental approaches, we improved the precision and the accuracy of the inter-dye distance distribution parameters by filtering out the donor-only population with pulsed interleaved excitation. A coarse-grained model is employed to reproduce the experimentally determined inter-dye distance distributions. This approach can easily be extended to intrinsically flexible proteins allowing, under certain conditions, to decouple the macromolecule amplitude of motions from the contribution of the dye linkers.

  2. Chemical Gas Sensors for Aeronautic and Space Applications 2

    Science.gov (United States)

    Hunter, G. W.; Chen, L. Y.; Neudeck, P. G.; Knight, D.; Liu, C. C.; Wu, Q. H.; Zhou, H. J.; Makel, D.; Liu, M.; Rauch, W. A.

    1998-01-01

    Aeronautic and Space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Areas of most interest include launch vehicle safety monitoring emission monitoring and fire detection. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensor is based on progress two types of technology: 1) Micro-machining and micro-fabrication technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this micro-fabricated gas sensor technology make this area of sensor development a field of significant interest.

  3. Chemical Gas Sensors for Aeronautics and Space Applications III

    Science.gov (United States)

    Hunter, G. W.; Neudeck, P. G.; Chen, L. Y.; Liu, C. C.; Wu, Q. H.; Sawayda, M. S.; Jin, Z.; Hammond, J.; Makel, D.; Liu, M.; hide

    1999-01-01

    Aeronautic and space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Areas of interest include launch vehicle safety monitoring, emission monitoring, and fire detection. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensors is based on progress in two types of technology: 1) Micromachining and microfabrication technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this microfabricated gas sensor technology make this area of sensor development a field of significant interest.

  4. UrtheCast Second-Generation Earth Observation Sensors

    Science.gov (United States)

    Beckett, K.

    2015-04-01

    UrtheCast's Second-Generation state-of-the-art Earth Observation (EO) remote sensing platform will be hosted on the NASA segment of International Space Station (ISS). This platform comprises a high-resolution dual-mode (pushbroom and video) optical camera and a dual-band (X and L) Synthetic Aperture RADAR (SAR) instrument. These new sensors will complement the firstgeneration medium-resolution pushbroom and high-definition video cameras that were mounted on the Russian segment of the ISS in early 2014. The new cameras are expected to be launched to the ISS in late 2017 via the Space Exploration Technologies Corporation Dragon spacecraft. The Canadarm will then be used to install the remote sensing platform onto a CBM (Common Berthing Mechanism) hatch on Node 3, allowing the sensor electronics to be accessible from the inside of the station, thus limiting their exposure to the space environment and allowing for future capability upgrades. The UrtheCast second-generation system will be able to take full advantage of the strengths that each of the individual sensors offers, such that the data exploitation capabilities of the combined sensors is significantly greater than from either sensor alone. This represents a truly novel platform that will lead to significant advances in many other Earth Observation applications such as environmental monitoring, energy and natural resources management, and humanitarian response, with data availability anticipated to begin after commissioning is completed in early 2018.

  5. Polymeric turbidity sensor fabricated by laser direct writing

    International Nuclear Information System (INIS)

    Li, Shu; Lin, Qiao; Wu, George; Chen, Liuhua; Wu, X

    2011-01-01

    The design of a miniature-sized turbidity sensor fabricated by laser direct writing was proposed and tested. A dual-beam dual-detector sensing structure was written by a 488 nm laser from UV curable optical polymer to form a 4 mm diameter turbidity sensing probe, with the fabrication process being shortened to a few seconds. Experimental tests on prototypes were conducted by using standard turbidity solutions, and the data were processed with a self-adapting neural network based on a single input single output algorithm. The scattering coefficient for normalized turbidity of the standards was obtained, and system accuracy was validated by an error analysis. Experimental results indicated that in the testing situation presented in this paper, the sensor was capable of responding to turbidity with a relative error of about 3%

  6. Microchamber arrays with an integrated long luminescence lifetime pH sensor.

    Science.gov (United States)

    Poehler, Elisabeth; Pfeiffer, Simon A; Herm, Marc; Gaebler, Michael; Busse, Benedikt; Nagl, Stefan

    2016-04-01

    A pH probe with a microsecond luminescence lifetime was obtained via covalent coupling of 6-carboxynaphthofluorescein (CNF) moieties to ruthenium-tris-(1,10-phenanthroline)(2+). The probe was covalently attached to amino-modified poly-(2-hydroxyethyl)methacrylate (pHEMA) and showed a pH-dependent FRET with luminescence lifetimes of 681 to 1260 ns and a working range from ca. pH 6.5 to 9.0 with a pKa of 7.79 ± 0.14. The pH sensor matrix was integrated via spin coating as ca. 1- to 2-μm-thick layer into "CytoCapture" cell culture dishes of 6 mm in diameter. These contained a microcavity array of square-shaped regions of 40 μm length and width and 15 μm depth that was homogeneously coated with the pH sensor matrix. The sensor layer showed fast response times in both directions. A microscopic setup was developed that enabled imaging of the pH inside the microchamber arrays over many hours. As a proof of principle, we monitored the pH of Escherichia coli cell cultures grown in the microchamber arrays. The integrated sensor matrix allowed pH monitoring spatially resolved in every microchamber, and the differences in cell growth between individual chambers could be resolved and quantified.

  7. Affordable dual-sensing proximity sensor for touchless interactive systems

    KAUST Repository

    Nassar, Joanna M.

    2016-09-13

    We report an ultra-low cost flexible proximity sensor using only off-the-shelf recyclable materials such as aluminum foil, napkin and double-sided tape. Unlike previous reports, our device structure exhibits two sensing capabilities in one platform, with outstanding long detection range of 20 cm and pressure sensitivity of 0.05 kPa. This is the first ever demonstration of a low-cost, accessible, and batch manufacturing process for pressure and proximity sensing on a singular platform. The mechanical flexibility of the sensor makes it possible to mount on various irregular platforms, which is vital in many areas, such as robotics, machine automation, vehicular technology and inspection tools.

  8. A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances

    Science.gov (United States)

    Tian, Yanqing; Fuller, Emily; Klug, Summer; Lee, Fred; Su, Fengyu; Zhang, Liqiang; Chao, Shih-hui; Meldrum, Deirdre R.

    2013-01-01

    A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter (SM1) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter (SM2) in poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 (PSM1) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 (PSM2) in the polymer matrices exhibited a vastly different response when compared to PSM1. The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor (PSM1,2) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2, which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488 nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and pKa). PMID:24078772

  9. A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances.

    Science.gov (United States)

    Tian, Yanqing; Fuller, Emily; Klug, Summer; Lee, Fred; Su, Fengyu; Zhang, Liqiang; Chao, Shih-Hui; Meldrum, Deirdre R

    2013-10-01

    A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter ( SM1 ) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter ( SM2 ) in poly(2-hydroxyethyl methacrylate)- co -polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 ( PSM1 ) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 ( PSM2 ) in the polymer matrices exhibited a vastly different response when compared to PSM1 . The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor ( PSM1,2 ) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2 , which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488 nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and p K a ).

  10. Coherent cavity-enhanced dual-comb spectroscopy.

    Science.gov (United States)

    Fleisher, Adam J; Long, David A; Reed, Zachary D; Hodges, Joseph T; Plusquellic, David F

    2016-05-16

    Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The dual combs were generated by driving the phase modulators with step-recovery diodes where each comb consisted of > 250 teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared. The step-recovery diodes are passive devices that provide low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely tunable dual-comb systems could enable a network of distributed multiplexed optical sensors.

  11. Evaluation of a color fused dual-band NVG

    NARCIS (Netherlands)

    Hogervorst, M.A.; Toet, A.

    2009-01-01

    We have tested a prototype dual-band NVG system consisting of two NVGs fitted with filters that split the NVG sensitive range into a short (visual) and a long wavelength (NIR) band. The Color-the-night technique (see Hogervorst & Toet, SPIE D&S ‘08) was used to fuse the images of the two sensors. We

  12. Dual-fuel engine with cylinder pressure based control

    Energy Technology Data Exchange (ETDEWEB)

    Ritscher, Bert [Caterpillar Motoren GmbH und Co. KG, Kiel (Germany). Large Power Systems Div.

    2013-10-15

    Cylinder pressure sensors were initially used to detect knocking and misfiring on spark ignited gas engines. On its latest MaK brand dual-fuel engine, Caterpillar Motoren is harnessing the deep insights into combustion and engine condition that can be derived direct from the origin of engine power in sophisticated control, monitoring and diagnostic systems. (orig.)

  13. A FRET-Based Approach for Quantitative Evaluation of Forskolin-Induced Pendrin Trafficking at the Plasma Membrane in Bronchial NCI H292 Cells

    Directory of Open Access Journals (Sweden)

    Grazia Tamma

    2013-12-01

    Full Text Available Background: Human pendrin (SLC26A4, PDS is an integral membrane protein acting as an electroneutral anion exchanger. Loss of function mutations in pendrin protein cause Pendred syndrome, a disorder characterized by sensorineural deafness and a partial iodide organification defect that may lead to thyroid goiter. Additionally, pendrin up-regulation could play a role in the pathogenesis of several diseases including bronchial asthma and chronic obstructive pulmonary disease (COPD. Therefore, monitoring the plasma membrane abundance and trafficking of pendrin in the context of a living cell is crucially important. Methods: Trafficking of pendrin to the plasma membrane was monitored by fluorescence resonance energy transfer (FRET, a physical phenomenon occurring between two fluorophores (the FRET donor and acceptor located in close spatial proximity. Because the efficiency of the energy transfer is inversely proportional to the sixth power of the distance between donor and acceptor, FRET is extremely sensitive to small changes in distance between the donor and acceptor and is therefore a powerful tool to determine protein-protein interactions. Results: FRET studies revealed that forskolin-induced cAMP production is associated with a significant increase of pendrin expression at plasma membrane, which is paralleled by a decrease in intracellular pH. Pendrin transposition to the membrane is accompanied with a partial depolymerization of actin cytoskeleton via Rho-GTPase inhibition. Conclusion: Trafficking to the plasma membrane is critical in the regulation of pendrin activity. Therefore, reliable tools for monitoring and quantifying this phenomenon are highly desirable.

  14. Optical probes in biology

    CERN Document Server

    Zhang, Jin; Schultz, Carsten

    2015-01-01

    Introduction and BasicsEngineering of Optimized Fluorescent Proteins: An Overview from a Cyan and FRET Perspective Lindsay Haarbosch, Joachim Goedhart, Mark A. Hink, Laura van Weeren, Daphne S. Bindels, and Theodorus W.J. GadellaFluorescent Imaging Techniques: FRET and Complementary Methods Stefan Terjung and Yury BelyaevTracking: Sensors for Tracking BiomoleculesProtein-Based Calcium Sensors Thomas Thestrup and Oliver GriesbeckMonitoring Membrane Lipids with Protein Domains Expressed in Living Cells Peter Varnai

  15. Sub-ensemble monitoring of DNA strand displacement using multiparameter single-molecule FRET

    OpenAIRE

    Baltierra Jasso, Laura; Morten, Michael; Magennis, Steven William

    2018-01-01

    Non-enzymatic DNA strand displacement is an important mechanism in dynamic DNA nanotechnology. Here we show that the large parameter space that is accessible by single-molecule FRET is ideal for the simultaneous monitoring of multiple reactants and products of DNA strand exchange reactions. We monitored the strand displacement from double-stranded DNA (dsDNA) by single-stranded DNA (ssDNA) at 37 °C; the data were modelled as a second-order reaction approaching equilibrium, with a rate constan...

  16. Dual lanthanide-doped complexes: the development of a time-resolved ratiometric fluorescent probe for anthrax biomarker and a paper-based visual sensor.

    Science.gov (United States)

    Wang, Qi-Xian; Xue, Shi-Fan; Chen, Zi-Han; Ma, Shi-Hui; Zhang, Shengqiang; Shi, Guoyue; Zhang, Min

    2017-08-15

    In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO 2 -Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO 2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO 2 -Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Decoupling of size and shape fluctuations in heteropolymeric sequences reconciles discrepancies in SAXS vs. FRET measurements.

    Science.gov (United States)

    Fuertes, Gustavo; Banterle, Niccolò; Ruff, Kiersten M; Chowdhury, Aritra; Mercadante, Davide; Koehler, Christine; Kachala, Michael; Estrada Girona, Gemma; Milles, Sigrid; Mishra, Ankur; Onck, Patrick R; Gräter, Frauke; Esteban-Martín, Santiago; Pappu, Rohit V; Svergun, Dmitri I; Lemke, Edward A

    2017-08-01

    Unfolded states of proteins and native states of intrinsically disordered proteins (IDPs) populate heterogeneous conformational ensembles in solution. The average sizes of these heterogeneous systems, quantified by the radius of gyration ( R G ), can be measured by small-angle X-ray scattering (SAXS). Another parameter, the mean dye-to-dye distance ( R E ) for proteins with fluorescently labeled termini, can be estimated using single-molecule Förster resonance energy transfer (smFRET). A number of studies have reported inconsistencies in inferences drawn from the two sets of measurements for the dimensions of unfolded proteins and IDPs in the absence of chemical denaturants. These differences are typically attributed to the influence of fluorescent labels used in smFRET and to the impact of high concentrations and averaging features of SAXS. By measuring the dimensions of a collection of labeled and unlabeled polypeptides using smFRET and SAXS, we directly assessed the contributions of dyes to the experimental values R G and R E For chemically denatured proteins we obtain mutual consistency in our inferences based on R G and R E , whereas for IDPs under native conditions, we find substantial deviations. Using computations, we show that discrepant inferences are neither due to methodological shortcomings of specific measurements nor due to artifacts of dyes. Instead, our analysis suggests that chemical heterogeneity in heteropolymeric systems leads to a decoupling between R E and R G that is amplified in the absence of denaturants. Therefore, joint assessments of R G and R E combined with measurements of polymer shapes should provide a consistent and complete picture of the underlying ensembles.

  18. Regulatory assembly of the vacuolar proton pump VoV1-ATPase in yeast cells by FLIM-FRET

    Science.gov (United States)

    Ernst, Stefan; Batisse, Claire; Zarrabi, Nawid; Böttcher, Bettina; Börsch, Michael

    2010-02-01

    We investigate the reversible disassembly of VOV1-ATPase in life yeast cells by time resolved confocal FRET imaging. VOV1-ATPase in the vacuolar membrane pumps protons from the cytosol into the vacuole. VOV1-ATPase is a rotary biological nanomotor driven by ATP hydrolysis. The emerging proton gradient is used for secondary transport processes as well as for pH and Ca2+ homoeostasis in the cell. The activity of the VOV1-ATPase is regulated through assembly / disassembly processes. During starvation the two parts of VOV1-ATPase start to disassemble. This process is reversed after addition of glucose. The exact mechanisms are unknown. To follow the disassembly / reassembly in vivo we tagged two subunits C and E with different fluorescent proteins. Cellular distributions of C and E were monitored using a duty cycle-optimized alternating laser excitation scheme (DCO-ALEX) for time resolved confocal FRET-FLIM measurements.

  19. Real-time monitoring of the Trojan-horse effect of silver nanoparticles by using a genetically encoded fluorescent cell sensor.

    Science.gov (United States)

    You, Fang; Tang, Wenqin; Yung, Lin-Yue Lanry

    2018-04-26

    Silver nanoparticles (AgNPs) are widely incorporated into commercial products due to their antimicrobial properties. As a consequence, concerns about the adverse effects induced by AgNPs to humans and the environment need to be carefully examined. The existing literature reveals that AgNPs exhibit certain toxic effects, but it remains to be proved whether AgNPs or the ionic silver (Ag+) released from AgNPs are the main toxic species. Here, a genetically encoded fluorescent protein sensor with high affinity to Ag+ was developed. The resulting sensor, MT2a-FRET, was found to be ratiometric, sensitive and selective toward only Ag+ but inert against AgNPs. This makes this sensor a potential useful tool for monitoring the real-time intracellular dissolutions of AgNPs. Our data supported that AgNPs display the "Trojan-horse" mechanism, where AgNPs are internalized by cells and undergo dissolution intracellularly. We further found that cells exhibited a detoxification ability to remove active Ag+ from cells in 48 hours.

  20. Lateral distribution of NBD-PC fluorescent lipid analogs in membranes probed by molecular dynamics-assisted analysis of Förster Resonance Energy Transfer (FRET) and fluorescence quenching.

    Science.gov (United States)

    Loura, Luís M S

    2012-11-08

    Förster resonance energy transfer (FRET) is a powerful tool used for many problems in membrane biophysics, including characterization of the lateral distribution of lipid components and other species of interest. However, quantitative analysis of FRET data with a topological model requires adequate choices for the values of several input parameters, some of which are difficult to obtain experimentally in an independent manner. For this purpose, atomistic molecular dynamics (MD) simulations can be potentially useful as they provide direct detailed information on transverse probe localization, relative probe orientation, and membrane surface area, all of which are required for analysis of FRET data. This is illustrated here for the FRET pairs involving 1,6-diphenylhexatriene (DPH) as donor and either 1-palmitoyl,2-(6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino] hexanoyl)- sn-glycero-3-phosphocholine (C6-NBD-PC) or 1-palmitoyl,2-(12-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]dodecanoyl)-sn-glycero-3-phosphocholine (C12-NBD-PC) as acceptors, in fluid vesicles of 1,2-dipalmitoyl-sn-3-glycerophosphocholine (DPPC, 50 °C). Incorporation of results from MD simulations improves the statistical quality of model fitting to the experimental FRET data. Furthermore, the decay of DPH in the presence of moderate amounts of C12-NBD-PC (>0.4 mol%) is consistent with non-random lateral distribution of the latter, at variance with C6-NBD-PC, for which aggregation is ruled out up to 2.5 mol% concentration. These conclusions are supported by analysis of NBD-PC fluorescence self-quenching. Implications regarding the relative utility of these probes in membrane studies are discussed.

  1. DUAL TIMELIKE NORMAL AND DUAL TIMELIKE SPHERICAL CURVES IN DUAL MINKOWSKI SPACE

    OpenAIRE

    ÖNDER, Mehmet

    2009-01-01

    Abstract: In this paper, we give characterizations of dual timelike normal and dual timelike spherical curves in the dual Minkowski 3-space and we show that every dual timelike normal curve is also a dual timelike spherical curve. Keywords: Normal curves, Dual Minkowski 3-Space, Dual Timelike curves. Mathematics Subject Classifications (2000): 53C50, 53C40. DUAL MINKOWSKI UZAYINDA DUAL TIMELIKE NORMAL VE DUAL TIMELIKE KÜRESEL EĞRİLER Özet: Bu çalışmada, dual Minkowski 3-...

  2. One-pot fabrication of FRET-based fluorescent probe for detecting copper ion and sulfide anion in 100% aqueous media

    Science.gov (United States)

    Lv, Kun; Chen, Jian; Wang, Hong; Zhang, Peisheng; Yu, Maolin; Long, Yunfei; Yi, Pinggui

    2017-04-01

    The design of effective tools for detecting copper ion (Cu2 +) and sulfide anion (S2 -) is of great importance due to the abnormal level of Cu2 + and S2 - has been associated with an increase in risk of many diseases. Herein, we report on the fabrication of fluorescence resonance energy transfer (FRET) based fluorescent probe PF (PEI-FITC) for detecting Cu2 + and S2 - in 100% aqueous media via a facile one-pot method by covalent linking fluorescein isothiocyanate (FITC) with branched-polyethylenimine (b-PEI). PF could selectively coordinate with Cu2 + among 10 metal ions to form PF-Cu2 + complex, resulting in fluorescence quenching through FRET mechanism. Furthermore, the in situ generated PF-Cu2 + complex can be used to selectively detect S2 - based on the displacement approach, resulting in an off-on type sensing. There is no obvious interference from other anions, such as Cl-, NO3-, ClO4-, SO42 -, HCO3-, CO32 -, Br-, HPO42 -, F- and S2O32 -. In addition, PF was successfully used to determine Cu2 + and S2 - in human serum and tap water samples. Therefore, the FRET-based probe PF may provide a new method for selective detection of multifarious analysts in biological and environmental applications, and even hold promise for application in more complicated systems.

  3. Förster Resonance Energy Transfer (FRET) between Heterogeneously Distributed Probes: Application to Lipid Nanodomains and Pores

    Czech Academy of Sciences Publication Activity Database

    Šachl, Radek; Johansson, L. B. A.; Hof, Martin

    2012-01-01

    Roč. 13, č. 12 (2012), s. 16141-16156 E-ISSN 1422-0067 R&D Projects: GA ČR GAP208/10/1090; GA ČR GAP208/10/0376 Institutional support: RVO:61388955 Keywords : FRET * lipid domains * pores Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.464, year: 2012

  4. Closed-loop System Identification with New Sensors

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Trangbæk, K; Stoustrup, Jakob

    2008-01-01

    This paper deals with system identification of new system dynamics revealed by online introduction of new sensors in existing multi-variable linear control systems. The so-called "Hansen Scheme" utilises the dual Youla-Kucera parameterisation of all systems stabilised by a given linear controller...... to transform closed-loop system identification problems into open-loop-like problems. We show that this scheme can be formally extended to accomodate extra sensors in a nice way. The approach is illustrated on a simple simulation example....

  5. Theoretical-experimental assessment of the variables affecting fretting of Atucha I nuclear power plant utility steam generators tubes

    International Nuclear Information System (INIS)

    Kulichevsky, Raul M.

    1995-01-01

    Fretting wear of Steam Generator tubes caused by flow induced vibrations generates uncertainty on their integrity. The knowledge of the controlling variables of the wear process may give a criterion to evaluate the tubes residual life. Information on vibratory response and dynamic interaction between tubes and their supports are prerequisites for understanding the relationship between fretting wear and tube vibration. Experimental results of the vibratory response of an Atucha-I nuclear power plant type U-tube, the influence of tube/support clearance on this response and a study of tube/support dynamic interaction, which allow the verification of a finite element model of this type of tubes, are presented in this work. Also wear results for the Incoloy 800/DIN 1.4550 austenitic stainless steel pair of materials and a first evaluation of the wear constant of this pair are presented. (author)

  6. A QM-MD simulation approach to the analysis of FRET processes in (bio)molecular systems. A case study: complexes of E. coli purine nucleoside phosphorylase and its mutants with formycin A.

    Science.gov (United States)

    Sobieraj, M; Krzyśko, K A; Jarmuła, A; Kalinowski, M W; Lesyng, B; Prokopowicz, M; Cieśla, J; Gojdź, A; Kierdaszuk, B

    2015-04-01

    Predicting FRET pathways in proteins using computer simulation techniques is very important for reliable interpretation of experimental data. A novel and relatively simple methodology has been developed and applied to purine nucleoside phosphorylase (PNP) complexed with a fluorescent ligand - formycin A (FA). FRET occurs between an excited Tyr residue (D*) and FA (A). This study aims to interpret experimental data that, among others, suggests the absence of FRET for the PNPF159A mutant in complex with FA, based on novel theoretical methodology. MD simulations for the protein molecule containing D*, and complexed with A, are carried out. Interactions of D* with its molecular environment are accounted by including changes of the ESP charges in S1, compared to S0, and computed at the SCF-CI level. FRET probability W F depends on the inverse six-power of the D*-A distance, R da . The orientational factor 0 < k(2) < 4 between D* and A is computed and included in the analysis. Finally W F is time-averaged over the MD trajectories resulting in its mean value. The red-shift of the tyrosinate anion emission and thus lack of spectral overlap integral and thermal energy dissipation are the reasons for the FRET absence in the studied mutants at pH 7 and above. The presence of the tyrosinate anion results in a competitive energy dissipation channel and red-shifted emission, thus in consequence in the absence of FRET. These studies also indicate an important role of the phenyl ring of Phe159 for FRET in the wild-type PNP, which does not exist in the Ala159 mutant, and for the effective association of PNP with FA. In a more general context, our observations point out very interesting and biologically important properties of the tyrosine residue in its excited state, which may undergo spontaneous deprotonation in the biomolecular systems, resulting further in unexpected physical and/or biological phenomena. Until now, this observation has not been widely discussed in the

  7. Evaluation of the Painful Dual Taper Modular Neck Stem Total Hip Arthroplasty: Do They All Require Revision?

    Science.gov (United States)

    Kwon, Young-Min

    2016-07-01

    Although dual taper modular-neck total hip arthroplasty (THA) design with additional neck-stem modularity has the potential to optimize hip biomechanical parameters by facilitating adjustments of leg length, femoral neck version and offset, there is increasing concern regarding this stem design as a result of the growing numbers of adverse local tissue reactions due to fretting and corrosion at the neck-stem taper junction. Implant factors such as taper cone angle, taper surface roughness, taper contact area, modular neck taper metallurgy, and femoral head size play important roles in influencing extent of taper corrosion. There should be a low threshold to conduct a systematic clinical evaluation of patients with dual-taper modular-neck stem THA using systematic risk stratification algorithms as early recognition and diagnosis will ensure prompt and appropriate treatment. Although specialized tests such as metal ion analysis and cross-sectional imaging modalities such as metal artifact reduction sequence magnetic resonance imaging (MARS MRI) are useful in optimizing clinical decision-making, overreliance on any single investigative tool in the clinical decision-making process for revision surgery should be avoided. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Experimental evaluation of the fretting fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2013-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. A method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires along the length of the monostrand. The experimental data....... Moreover, the paper provides relevant information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of the monostrand undergoing flexural deformations. The results presented herein are of special interest for the fatigue analysis of modern stay...

  9. Distributed Ship Navigation Control System Based on Dual Network

    Science.gov (United States)

    Yao, Ying; Lv, Wu

    2017-10-01

    Navigation system is very important for ship’s normal running. There are a lot of devices and sensors in the navigation system to guarantee ship’s regular work. In the past, these devices and sensors were usually connected via CAN bus for high performance and reliability. However, as the development of related devices and sensors, the navigation system also needs the ability of high information throughput and remote data sharing. To meet these new requirements, we propose the communication method based on dual network which contains CAN bus and industrial Ethernet. Also, we import multiple distributed control terminals with cooperative strategy based on the idea of synchronizing the status by multicasting UDP message contained operation timestamp to make the system more efficient and reliable.

  10. TECHNIQUE OF TESTING ON FRETTING AT THE SPHERE-TO-PLANE CONTACT

    Directory of Open Access Journals (Sweden)

    А. Khimko

    2012-12-01

    Full Text Available  The methodology of conducting tests on fretting at the sphere-to-plane contact was developed for the wing mechanization unit, namely for screw-nut pair with intermediate balls. Wearability tests were conducted on a modified installation МФК-1, the feature of which is the designed holder that allows testing with real balls. It was found that at the dry contact of ШХ-15 and 30Х2НВФA materials, surface microcracks are formed due to welding of microasperities areas and their rupture under the influence of vibration.

  11. Probing nucleic acid interactions and pre-mRNA splicing by Förster resonance energy transfer (FRET) microscopy

    Czech Academy of Sciences Publication Activity Database

    Šimková, Eva; Staněk, David

    2012-01-01

    Roč. 13, č. 11 (2012), s. 14929-14945 E-ISSN 1422-0067 R&D Projects: GA AV ČR KAN200520801 Institutional support: RVO:68378050 Keywords : FRET * FLIM * acceptor photobleaching * RNA interactions * spliceosome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.464, year: 2012

  12. FRET-based binding assay between a fluorescent cAMP analogue and a cyclic nucleotide-binding domain tagged with a CFP.

    Science.gov (United States)

    Romero, Francisco; Santana-Calvo, Carmen; Sánchez-Guevara, Yoloxochitl; Nishigaki, Takuya

    2017-09-01

    The cyclic nucleotide-binding domain (CNBD) functions as a regulatory domain of many proteins involved in cyclic nucleotide signalling. We developed a straightforward and reliable binding assay based on intermolecular fluorescence resonance energy transfer (FRET) between an adenosine-3', 5'-cyclic monophosphate analogue labelled with fluorescein and a recombinant CNBD of human EPAC1 tagged with a cyan fluorescence protein (CFP). The high FRET efficiency of this method (~ 80%) allowed us to perform several types of binding experiments with nanomolar range of sample using conventional equipment. In addition, the CFP tag on the CNBD enabled us to perform a specific binding experiment using an unpurified protein. Considering these advantages, this technique is useful to study poorly characterized CNBDs. © 2017 Federation of European Biochemical Societies.

  13. A novel method of measuring spatial rotation angle using MEMS tilt sensors

    International Nuclear Information System (INIS)

    Cao, Jian’an; Zhu, Xin; Zhang, Leping; Wu, Hao

    2017-01-01

    This paper presents a novel method of measuring spatial rotation angle with a dual-axis micro-electro-mechanical systems tilt sensor. When the sensor is randomly mounted on the surface of the rotating object, there are three unpredictable and unknown mounting position parameters: α , the sensor’s swing angle on the measuring plane; β , the angle between the rotation axis and the horizontal plane; and γ , the angle between the measuring plane and the rotation axis. Thus, the sensor’s spatial rotation model is established to describe the relationship between the measuring axis, rotation axis, and horizontal plane, and the corresponding analytical equations are derived. Furthermore, to eliminate the deviation caused by the uncertain direction of the rotation axis, an extra perpendicularly mounted, single-axis tilt sensor is combined with the dual-axis tilt sensor, forming a three-axis tilt sensor. Then, by measuring the sensors’ three tilts and solving the model’s equations, the object’s spatial rotation angle is obtained. Finally, experimental results show that the developed tilt sensor is capable of measuring spatial rotation angle in the range of  ±180° with an accuracy of 0.2° if the angle between the rotation axis and the horizontal plane is less than 75°. (paper)

  14. Fabrication of 3D Silicon Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kok, A.; Hansen, T.E.; Hansen, T.A.; Lietaer, N.; Summanwar, A.; /SINTEF, Oslo; Kenney, C.; Hasi, J.; /SLAC; Da Via, C.; /Manchester U.; Parker, S.I.; /Hawaii U.

    2012-06-06

    Silicon sensors with a three-dimensional (3-D) architecture, in which the n and p electrodes penetrate through the entire substrate, have many advantages over planar silicon sensors including radiation hardness, fast time response, active edge and dual readout capabilities. The fabrication of 3D sensors is however rather complex. In recent years, there have been worldwide activities on 3D fabrication. SINTEF in collaboration with Stanford Nanofabrication Facility have successfully fabricated the original (single sided double column type) 3D detectors in two prototype runs and the third run is now on-going. This paper reports the status of this fabrication work and the resulted yield. The work of other groups such as the development of double sided 3D detectors is also briefly reported.

  15. Chemical Gas Sensors for Aeronautic and Space Applications

    Science.gov (United States)

    Hunter, Gary W.; Chen, Liang-Yu; Neudeck, Philip G.; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai; Zhou, Huan-Jun

    1997-01-01

    Aeronautic and space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Two areas of particular interest are safety monitoring and emission monitoring. In safety monitoring, detection of low concentrations of hydrogen at potentially low temperatures is important while for emission monitoring the detection of nitrogen oxides, hydrogen, hydrocarbons and oxygen is of interest. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensors is based on progress in two types of technology: (1) Micromachining and microfabrication technology to fabricate miniaturized sensors. (2) The development of high temperature semiconductors, especially silicon carbide. The detection of each type of gas involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this microfabricated gas sensor technology make this general area of sensor development a field of significant interest.

  16. The role of two-phase coolant in moderating fretting in nuclear steam generators

    International Nuclear Information System (INIS)

    Dyke, J.M.

    2004-01-01

    This paper expands the principal of coolant-cushioning in Nuclear Steam Generators whereby the two-phase coolant, especially the bubble film on the tube surface, moderates the vibration of coolant tubes against their supports. The current paper addresses tube bundle and anti-vibration bars (AVB) geometry issues; examines the tube bundle-coolant-AVB interfaces and examines implications for recirculation flow, AVB design and boiler size. In a T(sat) fluid, the tube surface is uniformly coating with growing bubbles whose momentum is perpendicular to the surface at first, then they are swept away by the bulk flow. The combination of this momentum, the phase change and the water film remaining on the surface, counteract the vibration energy of the tube-AVB system, reducing the likelihood of metal-to-metal contact and consequent fretting. To maximize the benefit of the cushioning effect, the following design inputs are needed: 1) the AVB-tube interface should have sufficient clearance for the T(sat) solution to operate, 2) The AVB should be wide enough to generate the necessary cushioning force, and 3) the AVB should be thin enough to be flexible and absorb some of the transferred vibration energy. Furthermore, fretting and crude deposition at the AVB-tube interface can be reduced or eliminated by reducing the number of AVBs, increasing clearances and making the AVBs limber

  17. Electro-active sensor, method for constructing the same; apparatus and circuitry for detection of electro-active species

    Science.gov (United States)

    Buehler, Martin (Inventor)

    2009-01-01

    An electro-active sensor includes a nonconductive platform with a first electrode set attached with a first side of a nonconductive platform. The first electrode set serves as an electrochemical cell that may be utilized to detect electro-active species in solution. A plurality of electrode sets and a variety of additional electrochemical cells and sensors may be attached with the nonconductive platform. The present invention also includes a method for constructing the aforementioned electro-active sensor. Additionally, an apparatus for detection and observation is disclosed, where the apparatus includes a sealable chamber for insertion of a portion of an electro-active sensor. The apparatus allows for monitoring and detection activities. Allowing for control of attached cells and sensors, a dual-mode circuitry is also disclosed. The dual-mode circuitry includes a switch, allowing the circuitry to be switched from a potentiostat to a galvanostat mode.

  18. Assessment of Adaptive Rate Response Provided by Accelerometer, Minute Ventilation and Dual Sensor Compared with Normal Sinus Rhythm During Exercise: A Self-controlled Study in Chronotropically Competent Subjects

    Directory of Open Access Journals (Sweden)

    Yuanyuan Cao

    2015-01-01

    Full Text Available Background: Dual sensor (DS for rate adaption was supposed to be more physiological. To evaluate its superiority, the DS (accelerometer [ACC] and minute ventilation [MV] and normal sinus rate response were compared in a self-controlled way during exercise treadmill testing. Methods: This self-controlled study was performed in atrioventricular block patients with normal sinus function who met the indications of pacemaker implant. Twenty-one patients came to the 1-month follow-up visit. Patients performed a treadmill test 1-month post implant while programmed in DDDR and sensor passive mode. For these patients, sensor response factors were left at default settings (ACC = 8, MV = 3 and sensor indicated rates (SIRs for DS, ACC and MV sensor were retrieved from the pacemaker memories, along with measured sinus node (SN rates from the beginning to 1-minute after the end of the treadmill test, and compared among study groups. Repeated measures analysis of variance and profile analysis, as well as variance analysis of randomized block designs, were used for statistical analysis. Results: Fifteen patients (15/21 were determined to be chronotropically competent. The mean differences between DS SIRs and intrinsic sinus rates during treadmill testing were smaller than those for ACC and MV sensor (mean difference between SIR and SN rate: ACC vs. SN, MV vs. SN, DS vs. SN, respectively, 34.84, 17.60, 16.15 beats/min, though no sensors could mimic sinus rates under the default settings for sensor response factor (ACC vs. SN P-adjusted < 0.001; MV vs. SN P-adjusted = 0.002; DS vs. SN P-adjusted = 0.005. However, both in the range of 1 st minute and first 3 minutes of exercise, only the DS SIR profile did not differ from sinus rates (P-adjusted = 0.09, 0.90, respectively. Conclusions: The DS under default settings provides more physiological rate response during physical activity than the corresponding single sensors (ACC or MV sensor. Further study is needed to

  19. Failure of fretted steam generator tubes under accident conditions

    International Nuclear Information System (INIS)

    Forrest, C.F.

    1996-10-01

    Tests were carried out with a bank of tubes in a water tunnel to determine the tolerance of flawed nuclear reactor steam generator tubes to accident conditions which would result in high cross-flow velocities. Fourteen specimen tubes were tested, each having one or two types of defect machined into the surface simulating fretting-wear type scars found in some operating steam generators. The tubes were tested at flow velocities sufficient to induce high fluid elastic-type vibrations. Seven of the tubes failed near the thinnest section of the defects during the one-hour tests, due to impacting and/or rubbing between the tube and the support. Strain gauges, displacement transducers, force gauges and an accelerometer were used on the target tube and/or the tube immediately downstream of it to measure their vibrational characteristics

  20. Compact quantum dot-antibody conjugates for FRET immunoassays with subnanomolar detection limits

    Science.gov (United States)

    Mattera, Lucia; Bhuckory, Shashi; Wegner, K. David; Qiu, Xue; Agnese, Fabio; Lincheneau, Christophe; Senden, Tim; Djurado, David; Charbonnière, Loïc J.; Hildebrandt, Niko; Reiss, Peter

    2016-05-01

    A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post-functionalization with a heterobifunctional crosslinker, containing a lipoic acid group and a maleimide function, enabled the subsequent coupling to sulfhydryl groups of proteins. This was demonstrated by QD conjugation with fragmented antibodies (F(ab)). The obtained F(ab)-QD conjugates range among the smallest antibody-functionalized nanoprobes ever reported, with a hydrodynamic diameter coating for FRET could be demonstrated by an 6.2 and 2.5 fold improvement of the limit of detection (LOD) for PSA compared to commercially available hydrophilic QDs emitting at 605 and 705 nm, respectively. While the commercial QDs contain identical inorganic cores responsible for their fluorescence, they are coated with a comparably thick amphiphilic polymer layer leading to much larger hydrodynamic diameters (>26 nm without biomolecules). The LODs of 0.8 and 3.7 ng mL-1 obtained in 50 μL serum samples are below the clinical cut-off level of PSA (4 ng mL-1) and demonstrate their direct applicability in clinical diagnostics.A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post

  1. The Explicit Determinations Of Dual Plane Curves And Dual Helices In Terms Of Its Dual Curvature And Dual Torsion

    OpenAIRE

    Lee Jae Won; Choi Jin Ho; Jin Dae Ho

    2014-01-01

    In this paper, we give the explicit determinations of dual plane curves, general dual helices and dual slant helices in terms of its dual curvature and dual torsion as a fundamental theory of dual curves in a dual 3-space

  2. Intra-laser-cavity microparticle sensing with a dual-wavelength distributed-feedback laser

    NARCIS (Netherlands)

    Bernhardi, Edward H.; van der Werf, Kees O; Hollink, Anton J F; Wörhoff, Kerstin; de Ridder, René M; Subramaniam, Vinod; Pollnau, Markus

    An integrated intra-laser-cavity microparticle sensor based on a dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped amorphous aluminum oxide on a silicon substrate is demonstrated. Real-time detection and accurate size measurement of single micro-particles with diameters

  3. Affordable dual-sensing proximity sensor for touchless interactive systems

    KAUST Repository

    Nassar, Joanna M.; Diaz, Marlon C.; Hussain, Muhammad Mustafa

    2016-01-01

    We report an ultra-low cost flexible proximity sensor using only off-the-shelf recyclable materials such as aluminum foil, napkin and double-sided tape. Unlike previous reports, our device structure exhibits two sensing capabilities in one platform

  4. A Bayes-Maximum Entropy method for multi-sensor data fusion

    Energy Technology Data Exchange (ETDEWEB)

    Beckerman, M.

    1991-01-01

    In this paper we introduce a Bayes-Maximum Entropy formalism for multi-sensor data fusion, and present an application of this methodology to the fusion of ultrasound and visual sensor data as acquired by a mobile robot. In our approach the principle of maximum entropy is applied to the construction of priors and likelihoods from the data. Distances between ultrasound and visual points of interest in a dual representation are used to define Gibbs likelihood distributions. Both one- and two-dimensional likelihoods are presented, and cast into a form which makes explicit their dependence upon the mean. The Bayesian posterior distributions are used to test a null hypothesis, and Maximum Entropy Maps used for navigation are updated using the resulting information from the dual representation. 14 refs., 9 figs.

  5. Intonation and compensation of fretted string instruments

    Science.gov (United States)

    Varieschi, Gabriele; Gower, Christina

    2011-04-01

    We discuss theoretical and physical models that are useful for analyzing the intonation of musical instruments such as guitars and mandolins and can be used to improve the tuning on these instruments. The placement of frets on the fingerboard is designed according to mathematical rules and the assumption of an ideal string. The analysis becomes more complicated when we include the effects of deformation of the string and inharmonicity due to other string characteristics. As a consequence, perfect intonation of all the notes on the instrument cannot be achieved, but complex compensation procedures can be introduced to minimize the problem. To test the validity of these procedures, we performed extensive measurements using standard monochord sonometers and other acoustical devices, confirming the correctness of our theoretical models. These experimental activities can be integrated into acoustics courses and laboratories and can become a more advanced version of basic experiments with monochords and sonometers. This work was supported by a grant from the Frank R. Seaver College of Science and Engineering, Loyola Marymount University.

  6. Dual-color bioluminescent sensor proteins for therapeutic drug monitoring of antitumor antibodies

    NARCIS (Netherlands)

    van Rosmalen, M.; Ni, Y.; Vervoort, D.F.M.; Arts, R.; Ludwig, S.K.J.; Merkx, M.

    2018-01-01

    Monitoring the levels of therapeutic antibodies in individual patients would allow patient-specific dose optimization, with the potential for major therapeutic and financial benefits. Our group recently developed a new platform of bioluminescent sensor proteins (LUMABS; LUMinescent AntiBody Sensor)

  7. CO and CO2 dual-gas detection based on mid-infrared wideband absorption spectroscopy

    Science.gov (United States)

    Dong, Ming; Zhong, Guo-qiang; Miao, Shu-zhuo; Zheng, Chuan-tao; Wang, Yi-ding

    2018-03-01

    A dual-gas sensor system is developed for CO and CO2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing (TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million (ppm) in volume and 2.6 ppm for CO and CO2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO2, respectively. The reported sensor has potential applications in various fields requiring CO and CO2 detection such as in the coal mine.

  8. Precision and accuracy in smFRET based structural studies—A benchmark study of the Fast-Nano-Positioning System

    Science.gov (United States)

    Nagy, Julia; Eilert, Tobias; Michaelis, Jens

    2018-03-01

    Modern hybrid structural analysis methods have opened new possibilities to analyze and resolve flexible protein complexes where conventional crystallographic methods have reached their limits. Here, the Fast-Nano-Positioning System (Fast-NPS), a Bayesian parameter estimation-based analysis method and software, is an interesting method since it allows for the localization of unknown fluorescent dye molecules attached to macromolecular complexes based on single-molecule Förster resonance energy transfer (smFRET) measurements. However, the precision, accuracy, and reliability of structural models derived from results based on such complex calculation schemes are oftentimes difficult to evaluate. Therefore, we present two proof-of-principle benchmark studies where we use smFRET data to localize supposedly unknown positions on a DNA as well as on a protein-nucleic acid complex. Since we use complexes where structural information is available, we can compare Fast-NPS localization to the existing structural data. In particular, we compare different dye models and discuss how both accuracy and precision can be optimized.

  9. A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications

    Directory of Open Access Journals (Sweden)

    Syed Imran Hussain Shah

    2017-11-01

    Full Text Available In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900–1120 MHz and 15% (2.1–2.45 GHz for the unfolded state and 20% (1.3–1.6 GHz and 14% (2.3–2.5 GHz for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

  10. A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications.

    Science.gov (United States)

    Shah, Syed Imran Hussain; Lim, Sungjoon

    2017-11-20

    In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900-1120 MHz) and 15% (2.1-2.45 GHz) for the unfolded state and 20% (1.3-1.6 GHz) and 14% (2.3-2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

  11. NeuroSeek dual-color image processing infrared focal plane array

    Science.gov (United States)

    McCarley, Paul L.; Massie, Mark A.; Baxter, Christopher R.; Huynh, Buu L.

    1998-09-01

    Several technologies have been developed in recent years to advance the state of the art of IR sensor systems including dual color affordable focal planes, on-focal plane array biologically inspired image and signal processing techniques and spectral sensing techniques. Pacific Advanced Technology (PAT) and the Air Force Research Lab Munitions Directorate have developed a system which incorporates the best of these capabilities into a single device. The 'NeuroSeek' device integrates these technologies into an IR focal plane array (FPA) which combines multicolor Midwave IR/Longwave IR radiometric response with on-focal plane 'smart' neuromorphic analog image processing. The readout and processing integrated circuit very large scale integration chip which was developed under this effort will be hybridized to a dual color detector array to produce the NeuroSeek FPA, which will have the capability to fuse multiple pixel-based sensor inputs directly on the focal plane. Great advantages are afforded by application of massively parallel processing algorithms to image data in the analog domain; the high speed and low power consumption of this device mimic operations performed in the human retina.

  12. Expectation-maximization of the potential of mean force and diffusion coefficient in Langevin dynamics from single molecule FRET data photon by photon.

    Science.gov (United States)

    Haas, Kevin R; Yang, Haw; Chu, Jhih-Wei

    2013-12-12

    The dynamics of a protein along a well-defined coordinate can be formally projected onto the form of an overdamped Lagevin equation. Here, we present a comprehensive statistical-learning framework for simultaneously quantifying the deterministic force (the potential of mean force, PMF) and the stochastic force (characterized by the diffusion coefficient, D) from single-molecule Förster-type resonance energy transfer (smFRET) experiments. The likelihood functional of the Langevin parameters, PMF and D, is expressed by a path integral of the latent smFRET distance that follows Langevin dynamics and realized by the donor and the acceptor photon emissions. The solution is made possible by an eigen decomposition of the time-symmetrized form of the corresponding Fokker-Planck equation coupled with photon statistics. To extract the Langevin parameters from photon arrival time data, we advance the expectation-maximization algorithm in statistical learning, originally developed for and mostly used in discrete-state systems, to a general form in the continuous space that allows for a variational calculus on the continuous PMF function. We also introduce the regularization of the solution space in this Bayesian inference based on a maximum trajectory-entropy principle. We use a highly nontrivial example with realistically simulated smFRET data to illustrate the application of this new method.

  13. Evaluation of Sensor Configurations for Robotic Surgical Instruments.

    Science.gov (United States)

    Gómez-de-Gabriel, Jesús M; Harwin, William

    2015-10-27

    Designing surgical instruments for robotic-assisted minimally-invasive surgery (RAMIS) is challenging due to constraints on the number and type of sensors imposed by considerations such as space or the need for sterilization. A new method for evaluating the usability of virtual teleoperated surgical instruments based on virtual sensors is presented. This method uses virtual prototyping of the surgical instrument with a dual physical interaction, which allows testing of different sensor configurations in a real environment. Moreover, the proposed approach has been applied to the evaluation of prototypes of a two-finger grasper for lump detection by remote pinching. In this example, the usability of a set of five different sensor configurations, with a different number of force sensors, is evaluated in terms of quantitative and qualitative measures in clinical experiments with 23 volunteers. As a result, the smallest number of force sensors needed in the surgical instrument that ensures the usability of the device can be determined. The details of the experimental setup are also included.

  14. Dual Mode Sensing with Low-Profile Piezoelectric Thin Wafer Sensors for Steel Bridge Crack Detection and Diagnosis

    Directory of Open Access Journals (Sweden)

    Lingyu Yu

    2012-01-01

    Full Text Available Monitoring of fatigue cracking in steel bridges is of high interest to many bridge owners and agencies. Due to the variety of deterioration sources and locations of bridge defects, there is currently no single method that can detect and address the potential sources globally. In this paper, we presented a dual mode sensing methodology integrating acoustic emission and ultrasonic wave inspection based on the use of low-profile piezoelectric wafer active sensors (PWAS. After introducing the research background and piezoelectric sensing principles, PWAS crack detection in passive acoustic emission mode is first presented. Their acoustic emission detection capability has been validated through both static and compact tension fatigue tests. With the use of coaxial cable wiring, PWAS AE signal quality has been improved. The active ultrasonic inspection is conducted by the damage index and wave imaging approach. The results in the paper show that such an integration of passive acoustic emission detection with active ultrasonic sensing is a technological leap forward from the current practice of periodic and subjective visual inspection and bridge management based primarily on history of past performance.

  15. Effects of Contact Load on the Fretting Fatigue Behavior of IN-100 at Elevated Temperature

    Science.gov (United States)

    2009-03-01

    Effect of contact pressure on fretting fatigue of austenitic stainless steel ,” Tribology International, vol. 36, pp. 79-85, 2003. 155 [56] N.K. Naidu...austenitic stainless steel was presented. Like the studies in the previous section, this study investigated how a variably increased contact load...that their stainless steel specimens acted much in the same manner as the aluminum specimens presented in the previous section. It was observed

  16. A high sensitivity nanomaterial based SAW humidity sensor

    Energy Technology Data Exchange (ETDEWEB)

    Wu, T-T; Chou, T-H [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (China); Chen, Y-Y [Department of Mechanical Engineering, Tatung University, Taipei 104, Taiwan (China)], E-mail: wutt@ndt.iam.ntu.edu.tw

    2008-04-21

    In this paper, a highly sensitive humidity sensor is reported. The humidity sensor is configured by a 128{sup 0}YX-LiNbO{sub 3} based surface acoustic wave (SAW) resonator whose operating frequency is at 145 MHz. A dual delay line configuration is realized to eliminate external temperature fluctuations. Moreover, for nanostructured materials possessing high surface-to-volume ratio, large penetration depth and fast charge diffusion rate, camphor sulfonic acid doped polyaniline (PANI) nanofibres are synthesized by the interfacial polymerization method and further deposited on the SAW resonator as selective coating to enhance sensitivity. The humidity sensor is used to measure various relative humidities in the range 5-90% at room temperature. Results show that the PANI nanofibre based SAW humidity sensor exhibits excellent sensitivity and short-term repeatability.

  17. Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

    Science.gov (United States)

    Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

    1999-01-01

    Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a

  18. Fretting Fatigue Behaviour of Pin-Loaded Thermoset Carbon-Fibre-Reinforced Polymer (CFRP Straps

    Directory of Open Access Journals (Sweden)

    Fabio Baschnagel

    2016-04-01

    Full Text Available This paper focuses on the fretting fatigue behaviour of pin-loaded carbon-fibre-reinforced polymer (CFRP straps studied as models for rigging systems in sailing yachts, for suspenders of arch bridges and for pendent cables in cranes. Eight straps were subjected to an ultimate tensile strength test. In total, 26 straps were subjected to a fretting fatigue test, of which ten did not fail. An S–N curve was generated for a load ratio R of 0.1 and a frequency f of 10 Hz, showing a fatigue limit stress of the straps around the matrix fatigue limit, corresponding to 46% of the straps’ ultimate tensile strength (σUTS. The fatigue limit was defined as 3 million load cycles (N = 3 × 106, but tests were even conducted up to N = 11.09 × 106. Catastrophic failure of the straps was initiated in their vertex areas. Investigations on the residual strength and stiffness properties of straps tested around the fatigue limit stress (for N ≥ 1 × 106 showed little influence of the fatigue loading on these properties. Quasi-static finite element analyses (FEA were conducted. The results obtained from the FEA are in good agreement with the experiments and demonstrate a fibre parallel stress concentration in the vertex area of factor 1.3, under the realistic assumption of a coefficient of friction (cof between pin and strap of 0.5.

  19. The 1.6 Å resolution structure of a FRET-optimized Cerulean fluorescent protein

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, Jennifer L.; Kim, Hanseong [Arizona State University, Tempe, AZ 85287-1604 (United States); Markwardt, Michele L. [University of Maryland School of Medicine, Baltimore, MD 21201-1559 (United States); Chen, Liqing; Fromme, Raimund [Arizona State University, Tempe, AZ 85287-1604 (United States); Rizzo, Mark A. [University of Maryland School of Medicine, Baltimore, MD 21201-1559 (United States); Wachter, Rebekka M., E-mail: rwachter@asu.edu [Arizona State University, Tempe, AZ 85287-1604 (United States)

    2013-05-01

    The high resolution X-ray structure of the cyan fluorescent protein mCerulean3 demonstrates that different combinations of correlated residue substitutions can provide near optimum quantum yield values for fluorescence. Genetically encoded cyan fluorescent proteins (CFPs) bearing a tryptophan-derived chromophore are commonly used as energy-donor probes in Förster resonance energy transfer (FRET) experiments useful in live cell-imaging applications. In recent years, significant effort has been expended on eliminating the structural and excited-state heterogeneity of these proteins, which has been linked to undesirable photophysical properties. Recently, mCerulean3, a descendant of enhanced CFP, was introduced as an optimized FRET donor protein with a superior quantum yield of 0.87. Here, the 1.6 Å resolution X-ray structure of mCerulean3 is reported. The chromophore is shown to adopt a planar trans configuration at low pH values, indicating that the acid-induced isomerization of Cerulean has been eliminated. β-Strand 7 appears to be well ordered in a single conformation, indicating a loss of conformational heterogeneity in the vicinity of the chromophore. Although the side chains of Ile146 and Leu167 appear to exist in two rotamer states, they are found to be well packed against the indole group of the chromophore. The Ser65 reversion mutation allows improved side-chain packing of Leu220. A structural comparison with mTurquoise2 is presented and additional engineering strategies are discussed.

  20. The 1.6 Å resolution structure of a FRET-optimized Cerulean fluorescent protein

    International Nuclear Information System (INIS)

    Watkins, Jennifer L.; Kim, Hanseong; Markwardt, Michele L.; Chen, Liqing; Fromme, Raimund; Rizzo, Mark A.; Wachter, Rebekka M.

    2013-01-01

    The high resolution X-ray structure of the cyan fluorescent protein mCerulean3 demonstrates that different combinations of correlated residue substitutions can provide near optimum quantum yield values for fluorescence. Genetically encoded cyan fluorescent proteins (CFPs) bearing a tryptophan-derived chromophore are commonly used as energy-donor probes in Förster resonance energy transfer (FRET) experiments useful in live cell-imaging applications. In recent years, significant effort has been expended on eliminating the structural and excited-state heterogeneity of these proteins, which has been linked to undesirable photophysical properties. Recently, mCerulean3, a descendant of enhanced CFP, was introduced as an optimized FRET donor protein with a superior quantum yield of 0.87. Here, the 1.6 Å resolution X-ray structure of mCerulean3 is reported. The chromophore is shown to adopt a planar trans configuration at low pH values, indicating that the acid-induced isomerization of Cerulean has been eliminated. β-Strand 7 appears to be well ordered in a single conformation, indicating a loss of conformational heterogeneity in the vicinity of the chromophore. Although the side chains of Ile146 and Leu167 appear to exist in two rotamer states, they are found to be well packed against the indole group of the chromophore. The Ser65 reversion mutation allows improved side-chain packing of Leu220. A structural comparison with mTurquoise2 is presented and additional engineering strategies are discussed

  1. Optical bar code recognition of methyl salicylate (MES) for environmental monitoring using fluorescence resonance energy transfer (FRET) on thin films

    Science.gov (United States)

    Smith, Clint; Tatineni, Balaji; Anderson, John; Tepper, Gary

    2006-10-01

    Fluorescence resonance energy transfer (FRET) is a process in which energy is transferred nonradiatively from one fluorophore (the donor) in an excited electron state to another, the chromophore (the acceptor). FRET is distinctive in its ability to reveal the presence of specific recognition of select targets such as the nerve agent stimulant Methyl Salicylate (MES) upon spectroscopic excitation. We introduce a surface imprinted and non-imprinted thin film that underwent AC-Electrospray ionization for donor-acceptor pair(s) bound to InGaP quantum dots and mesoporous silicate nanoparticles. The donor-acceptor pair used in this investigation included MES (donor) and 6-(fluorescein-5-(and-6)- carboxamido) hexanoic acid, succinimidyl ester bound to InGaP quantum dots (acceptor). MES was then investigated as a donor to various acceptor fluorophore: InGaP: mesoporous silicate nanoparticle layers.

  2. Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

    Science.gov (United States)

    Chou, Kenny F.; Dennis, Allison M.

    2015-01-01

    Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting. PMID:26057041

  3. Towards characterization of DNA structure under physiological conditions in vivo at the single-molecule level using single-pair FRET

    Czech Academy of Sciences Publication Activity Database

    Fessl, Tomáš; Adamec, František; Polívka, Tomáš; Foldynová-Trantírková, Silvie; Vácha, František; Trantírek, L.

    2012-01-01

    Roč. 40, č. 16 (2012), s. 10 ISSN 0305-1048 Institutional research plan: CEZ:AV0Z50510513; CEZ:AV0Z60220518 Keywords : in-cell FRET * fluorescence * DNA * nucleic acid * ATTO * in vivo Subject RIV: BO - Biophysics Impact factor: 8.278, year: 2012

  4. Modeling of fuel bundle vibration and the associated fretting wear in a CANDU fuel channel

    International Nuclear Information System (INIS)

    Mohany, A.; Hassan, M.

    2011-01-01

    In this paper a numerical model is developed to predict the vibration response of a CANDU® fuel bundle and the associated fretting wear in the surrounding pressure tube. One excitation mechanism is considered in this model; turbulence-induced excitation caused by coolant flow inside the fuel channel. The numerical model can be easily adapted to include the effects of seismic events, fuel bundle impact during refuelling and start-up of the reactor, and the acoustic pressure pulsations caused by the primary heat transport (PHT) pumps. The simulation is performed for a typical CANDU fuel bundle with 37 fuel elements. The clearances between the buttons of the inner fuel elements, and between the bearing pads of the outer fuel elements and the pressure tube were measured from an actual fuel bundle. Some variability among the measured clearance values was observed. Therefore, probability density functions of the measured clearance values were established and the simulation was performed for the probabilistic distribution of the clearance values. The contact between the fuel bundle and the pressure tube is modeled using pseudo-force contact method. The proposed modelling technique can be used in future CANDU reactors to avoid fuel and pressure tube fretting damage due to the aforementioned excitation mechanisms. (author)

  5. Nanoparticle assembled microcapsules for application as pH and ammonia sensor

    International Nuclear Information System (INIS)

    Amali, Arlin Jose; Awwad, Nour H.; Rana, Rohit Kumar; Patra, Digambara

    2011-01-01

    Graphical abstract: HPTS encapsulated nanoparticle assembled microcapsule is exploited as dual excitations ratiometic pH sensor. This nanoparticle assembled microcapsule based fluorescence sensor can determine ammonia and offers a robust, simple and fast sensing material. Highlights: ► A novel HPTS encapsulated nanoparticle assembled microcapsule is developed. ► Its dual excitation facilitates a ratiometic pH sensor. ► It is successfully applied for the determination of ammonia. ► It provides a robust, simple and fast sensing material. - Abstract: The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8–8.0, and can be successfully applied for the determination of ammonia in the concentration range 0–1.2 mM, which is important for aquatic life and the environment.

  6. Fretting-wear characteristics of steam generator tubes contacting with foreign object

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Jhung, Myung Jo; Kim, Woong Sik; Kim, Hho Jung

    2003-01-01

    Fretting-wear characteristics of steam generator tubes contacting with foreign object has been investigated in this study. The operating steam generator shell-side flow field conditions are obtained from three-dimensional steam generator flow calculation using a well-validated steam generator thermal-hydraulic analysis computer code. Modal analyses are performed for the finite element modelings of tubes to get the natural frequency, corresponding mode shape and participation factor. The wear rate of a steam generator tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted. In addition, the effects of internal pressure and flow velocity on the remaining life of the tube are discussed in this paper

  7. Contribución al desarrollo de sensores de temperatura y redes de sensores en tecnología de fibra óptica

    OpenAIRE

    Madruga Saavedra, Francisco Javier

    2006-01-01

    Este trabajo de tesis recoge las contribuciones aportadas en el campo de los sensores de fibra óptica en tres ámbitos de trabajo. Un sistema sensor de alta temperatura sin contacto con transductores de fibras ópticas de sílice se ha presentado. Dos topologías de "ojo abierto" y "ojo cerrado" y un algoritmo de decodificación "pirometría de banda dual" propuesto en este trabajo son las novedosas aportaciones presentadas. El sistema ha sido validado en laboratorio y en pruebas de campo de forma ...

  8. Contribución al desarrollo de sensores de temperatura y redes de sensores en tecnología de fibra óptica

    OpenAIRE

    Madruga Saavedra, Francisco Javier

    2008-01-01

    RESUMEN: Este trabajo de tesis recoge las contribuciones aportadas en el campo de los sensores de fibra óptica en tres ámbitos de trabajo. Un sistema sensor de alta temperatura sin contacto con transductores de fibras ópticas de sílice se ha presentado. Dos topologías de "ojo abierto" y "ojo cerrado" y un algoritmo de decodificación "pirometría de banda dual" propuesto en este trabajo son las novedosas aportaciones presentadas. El sistema ha sido validado en laboratorio y en pruebas de campo ...

  9. Directly Printable Flexible Strain Sensors for Bending and Contact Feedback of Soft Actuators

    Directory of Open Access Journals (Sweden)

    Khaled Elgeneidy

    2018-02-01

    Full Text Available This paper presents a fully printable sensorized bending actuator that can be calibrated to provide reliable bending feedback and simple contact detection. A soft bending actuator following a pleated morphology, as well as a flexible resistive strain sensor, were directly 3D printed using easily accessible FDM printer hardware with a dual-extrusion tool head. The flexible sensor was directly welded to the bending actuator’s body and systematically tested to characterize and evaluate its response under variable input pressure. A signal conditioning circuit was developed to enhance the quality of the sensory feedback, and flexible conductive threads were used for wiring. The sensorized actuator’s response was then calibrated using a vision system to convert the sensory readings to real bending angle values. The empirical relationship was derived using linear regression and validated at untrained input conditions to evaluate its accuracy. Furthermore, the sensorized actuator was tested in a constrained setup that prevents bending, to evaluate the potential of using the same sensor for simple contact detection by comparing the constrained and free-bending responses at the same input pressures. The results of this work demonstrated how a dual-extrusion FDM printing process can be tuned to directly print highly customizable flexible strain sensors that were able to provide reliable bending feedback and basic contact detection. The addition of such sensing capability to bending actuators enhances their functionality and reliability for applications such as controlled soft grasping, flexible wearables, and haptic devices.

  10. A homogeneous fluorometric assay platform based on novel synthetic proteins

    International Nuclear Information System (INIS)

    Vardar-Schara, Goenuel; Krab, Ivo M.; Yi, Guohua; Su, Wei Wen

    2007-01-01

    Novel synthetic recombinant sensor proteins have been created to detect analytes in solution, in a rapid single-step 'mix and read' noncompetitive homogeneous assay process, based on modulating the Foerster resonance energy transfer (FRET) property of the sensor proteins upon binding to their targets. The sensor proteins comprise a protein scaffold that incorporates a specific target-capturing element, sandwiched by genetic fusion between two molecules that form a FRET pair. The utility of the sensor proteins was demonstrated via three examples, for detecting an anti-biotin Fab antibody, a His-tagged recombinant protein, and an anti-FLAG peptide antibody, respectively, all done directly in solution. The diversity of sensor-target interactions that we have demonstrated in this study points to a potentially universal applicability of the biosensing concept. The possibilities for integrating a variety of target-capturing elements with a common sensor scaffold predict a broad range of practical applications

  11. Assessment of fretting wear in Hanaro fuel

    International Nuclear Information System (INIS)

    Chae, Hee Taek; Lim, Kyeong Hwan; Kim, Hark Rho

    1999-06-01

    Since the first fuel loading on Feb. 1995, various zero-power tests were performed in HANARO and power ascending tests followed. After the initial fuel loading, Hanaro operation staffs inspected only two fuel bundles which were evaluated to have the highest power at the end of each cycle and they did not recognize anything peculiar in the inspected bundles. At the end of 1996, Hanaro staffs found severe wear damages in the fuel components. After that, the 4th cycle core was re-arranged with fresh fuels only to investigate wear phenomena on the fuel components. The fuel inspections have been performed 25 times periodically since the core re-configuration. In this report, fretting wear characteristics of the fuel assemblies were evaluated and summarized. Wear damages of the improved fuel assembly to resolve the wear problem were compared with those of the original fuel assembly. Based on the results of the fuel inspections, we suggest that fuel inspection need not be done for the first 60 pump operation days in order to reduce the potential of damage by a fuel handling error and an operator's burden of the fuel inspection. (author). 6 refs., 10 tabs., 5 figs

  12. Compact, Low-Noise Magnetic Sensor with Fluxgate (DC) and Induction (AC) Modes of Operation

    Science.gov (United States)

    2009-07-01

    induction sensor and the fluxgate magnetometer . ......................................... 2 Figure 3.1 - Impulse response of a 4” long coil (#6...Block diagram of the Year 2, Task 2 fluxgate magnetometer . ................................... 6 Figure 3.3 - FIS-prototype magnetic-field...and demonstrated an innovative dual-mode, fluxgate -induction sensor (FIS) that combines a fluxgate magnetometer and an electromagnetic (EM) induction

  13. Dual-anticipating, dual and dual-lag synchronization in modulated time-delayed systems

    International Nuclear Information System (INIS)

    Ghosh, Dibakar; Chowdhury, A. Roy

    2010-01-01

    In this Letter, dual synchronization in modulated time delay system using delay feedback controller is proposed. Based on Lyapunov stability theory, we suggest a general method to achieve the dual-anticipating, dual, dual-lag synchronization of time-delayed chaotic systems and we find both its existing and sufficient stability conditions. Numerically it is shown that the dual synchronization is also possible when driving system contain two completely different systems. Effect of parameter mismatch on dual synchronization is also discussed. As an example, numerical simulations for the Mackey-Glass and Ikeda systems are conducted, which is in good agreement with the theoretical analysis.

  14. Efficient placement of structural dynamics sensors on the space station

    Science.gov (United States)

    Lepanto, Janet A.; Shepard, G. Dudley

    1987-01-01

    System identification of the space station dynamic model will require flight data from a finite number of judiciously placed sensors on it. The placement of structural dynamics sensors on the space station is a particularly challenging problem because the station will not be deployed in a single mission. Given that the build-up sequence and the final configuration for the space station are currently undetermined, a procedure for sensor placement was developed using the assembly flights 1 to 7 of the rephased dual keel space station as an example. The procedure presented approaches the problem of placing the sensors from an engineering, as opposed to a mathematical, point of view. In addition to locating a finite number of sensors, the procedure addresses the issues of unobserved structural modes, dominant structural modes, and the trade-offs involved in sensor placement for space station. This procedure for sensor placement will be applied to revised, and potentially more detailed, finite element models of the space station configuration and assembly sequence.

  15. Live-cell FRET imaging reveals clustering of the prion protein at the cell surface induced by infectious prions.

    Science.gov (United States)

    Tavares, Evandro; Macedo, Joana A; Paulo, Pedro M R; Tavares, Catarina; Lopes, Carlos; Melo, Eduardo P

    2014-07-01

    Prion diseases are associated to the conversion of the prion protein into a misfolded pathological isoform. The mechanism of propagation of protein misfolding by protein templating remains largely unknown. Neuroblastoma cells were transfected with constructs of the prion protein fused to both CFP-GPI-anchored and to YFP-GPI-anchored and directed to its cell membrane location. Live-cell FRET imaging between the prion protein fused to CFP or YFP was measured giving consistent values of 10±2%. This result was confirmed by fluorescence lifetime imaging microscopy and indicates intermolecular interactions between neighbor prion proteins. In particular, considering that a maximum FRET efficiency of 17±2% was determined from a positive control consisting of a fusion CFP-YFP-GPI-anchored. A stable cell clone expressing the two fusions containing the prion protein was also selected to minimize cell-to-cell variability. In both, stable and transiently transfected cells, the FRET efficiency consistently increased in the presence of infectious prions - from 4±1% to 7±1% in the stable clone and from 10±2% to 16±1% in transiently transfected cells. These results clearly reflect an increased clustering of the prion protein on the membrane in the presence of infectious prions, which was not observed in negative control using constructs without the prion protein and upon addition of non-infected brain. Our data corroborates the recent view that the primary site for prion conversion is the cell membrane. Since our fluorescent cell clone is not susceptible to propagate infectivity, we hypothesize that the initial event of prion infectivity might be the clustering of the GPI-anchored prion protein. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    Science.gov (United States)

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  17. Multi-Sensor Systems Development for UXO Detection and Discrimination: Hand-Held Dual Magnetic/Electromagnetic Induction Sensor

    National Research Council Canada - National Science Library

    Wright, David; Bennett, Jr., , Hollis H; Dove, Linda P; Butler, Dwain K

    2008-01-01

    ...) detection and discrimination system. This breakthrough technology markedly reduces UXO false alarm rates by fusing two heretofore incompatible sensor platforms, integrating highly accurate spatial data in real time, and applying...

  18. Design specifications to ensure flow-induced vibration and fretting-wear performance in CANDU steam generators and heat exchangers

    International Nuclear Information System (INIS)

    Janzen, V.P.; Han, Y.; Pettigrew, M.J.

    2009-01-01

    Preventing flow-induced vibration and fretting-wear problems in steam generators and heat exchangers requires design specifications that bring together specific guidelines, analysis methods, requirements and appropriate performance criteria. This paper outlines the steps required to generate and support such design specifications for CANDU nuclear steam generators and heat exchangers, and relates them to typical steam-generator design features and computer modeling capabilities. It also describes current issues that are driving changes to flow-induced vibration and fretting-wear specifications that can be applied to the design process for component refurbishment, replacement or new designs. These issues include recent experimental or field evidence for new excitation mechanisms, e.g., the possibility of in-plane fluidelastic instability of U-tubes, the demand for longer reactor and component lifetimes, the need for better predictions of dynamic properties and vibration response, e.g., two-phase random-turbulence excitation, and requirements to consider system 'excursions' or abnormal scenarios, e.g., a main steam line break in the case of steam generators. The paper describes steps being taken to resolve these issues. (author)

  19. Quantitative FLIM-FRET Microscopy to Monitor Nanoscale Chromatin Compaction In Vivo Reveals Structural Roles of Condensin Complexes

    Directory of Open Access Journals (Sweden)

    David Llères

    2017-02-01

    Full Text Available How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer-based fluorescence lifetime imaging microscopy (FLIM approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells. Using RNAi and repetitive extrachromosomal array approaches, we defined the heterochromatin state and showed that its architecture presents a nanoscale-compacted organization controlled by Heterochromatin Protein-1 (HP1 and SETDB1 H3-lysine-9 methyltransferase homologs in vivo. Next, we functionally explored condensin complexes. We found that condensin I and condensin II are essential for heterochromatin compaction and that condensin I additionally controls lowly compacted regions. Our data show that, in living animals, nanoscale chromatin compaction is controlled not only by histone modifiers and readers but also by condensin complexes.

  20. Evaluation of Sensor Configurations for Robotic Surgical Instruments

    Directory of Open Access Journals (Sweden)

    Jesús M. Gómez-de-Gabriel

    2015-10-01

    Full Text Available Designing surgical instruments for robotic-assisted minimally-invasive surgery (RAMIS is challenging due to constraints on the number and type of sensors imposed by considerations such as space or the need for sterilization. A new method for evaluating the usability of virtual teleoperated surgical instruments based on virtual sensors is presented. This method uses virtual prototyping of the surgical instrument with a dual physical interaction, which allows testing of different sensor configurations in a real environment. Moreover, the proposed approach has been applied to the evaluation of prototypes of a two-finger grasper for lump detection by remote pinching. In this example, the usability of a set of five different sensor configurations, with a different number of force sensors, is evaluated in terms of quantitative and qualitative measures in clinical experiments with 23 volunteers. As a result, the smallest number of force sensors needed in the surgical instrument that ensures the usability of the device can be determined. The details of the experimental setup are also included.

  1. Evaluation of Sensor Configurations for Robotic Surgical Instruments

    Science.gov (United States)

    Gómez-de-Gabriel, Jesús M.; Harwin, William

    2015-01-01

    Designing surgical instruments for robotic-assisted minimally-invasive surgery (RAMIS) is challenging due to constraints on the number and type of sensors imposed by considerations such as space or the need for sterilization. A new method for evaluating the usability of virtual teleoperated surgical instruments based on virtual sensors is presented. This method uses virtual prototyping of the surgical instrument with a dual physical interaction, which allows testing of different sensor configurations in a real environment. Moreover, the proposed approach has been applied to the evaluation of prototypes of a two-finger grasper for lump detection by remote pinching. In this example, the usability of a set of five different sensor configurations, with a different number of force sensors, is evaluated in terms of quantitative and qualitative measures in clinical experiments with 23 volunteers. As a result, the smallest number of force sensors needed in the surgical instrument that ensures the usability of the device can be determined. The details of the experimental setup are also included. PMID:26516863

  2. Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes

    Directory of Open Access Journals (Sweden)

    Shaowei Ding

    2015-06-01

    Full Text Available Nanocarbon allotropes (NCAs, including zero-dimensional carbon dots (CDs, one-dimensional carbon nanotubes (CNTs and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET. This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed.

  3. Development of a bifunctional sensor using haptenized acetylcholinesterase and application for the detection of cocaine and organophosphates

    NARCIS (Netherlands)

    Teller, Carsten; Halamek, J.; Žeravík, Jiri; Stöcklein, Walter F.M.; Scheller, Frieder W.

    2008-01-01

    We developed a dual piezoelectric/amperometric sensor for the detection of two unrelated analytes in one experiment that uses propidium to anchor acetylcholinesterases (AChE) at the surface. This mass-sensitive sensor does not only allow the examination of the interaction between AChE and the

  4. Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

    Directory of Open Access Journals (Sweden)

    Kenny F. Chou

    2015-06-01

    Full Text Available Förster (or fluorescence resonance energy transfer amongst semiconductor quantum dots (QDs is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

  5. Quantitative Analysis of Tau-Microtubule Interaction Using FRET

    Directory of Open Access Journals (Sweden)

    Isabelle L. Di Maïo

    2014-08-01

    Full Text Available The interaction between the microtubule associated protein, tau and the microtubules is investigated. A fluorescence resonance energy transfer (FRET assay was used to determine the distance separating tau to the microtubule wall, as well as the binding parameters of the interaction. By using microtubules stabilized with Flutax-2 as donor and tau labeled with rhodamine as acceptor, a donor-to-acceptor distance of 54 ± 1 Å was found. A molecular model is proposed in which Flutax-2 is directly accessible to tau-rhodamine molecules for energy transfer. By titration, we calculated the stoichiometric dissociation constant to be equal to 1.0 ± 0.5 µM. The influence of the C-terminal tails of αβ-tubulin on the tau-microtubule interaction is presented once a procedure to form homogeneous solution of cleaved tubulin has been determined. The results indicate that the C-terminal tails of α- and β-tubulin by electrostatic effects and of recruitment seem to be involved in the binding mechanism of tau.

  6. Mitochondrial intermediate peptidase: Expression in Escherichia coli and improvement of its enzymatic activity detection with FRET substrates

    International Nuclear Information System (INIS)

    Marcondes, Marcelo F.; Torquato, Ricardo J.S.; Assis, Diego M.; Juliano, Maria A.; Hayashi, Mirian A.F.; Oliveira, Vitor

    2010-01-01

    In the present study, soluble, functionally-active, recombinant human mitochondrial intermediate peptidase (hMIP), a mitochondrial metalloendoprotease, was expressed in a prokaryotic system. The hMIP fusion protein, with a poly-His-tag (6x His), was obtained by cloning the coding region of hMIP cDNA into the pET-28a expression vector, which was then used to transform Escherichia coli BL21 (DE3) pLysS. After isolation and purification of the fusion protein by affinity chromatography using Ni-Sepharose resin, the protein was purified further using ion exchange chromatography with a Hi-trap resource Q column. The recombinant hMIP was characterized by Western blotting using three distinct antibodies, circular dichroism, and enzymatic assays that used the first FRET substrates developed for MIP and a series of protease inhibitors. The successful expression of enzymatically-active hMIP in addition to the FRET substrates will contribute greatly to the determination of substrate specificity of this protease and to the development of specific inhibitors that are essential for a better understanding of the role of this protease in mitochondrial functioning.

  7. High-accuracy self-calibration method for dual-axis rotation-modulating RLG-INS

    Science.gov (United States)

    Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Long, Xingwu

    2017-05-01

    Inertial navigation system has been the core component of both military and civil navigation systems. Dual-axis rotation modulation can completely eliminate the inertial elements constant errors of the three axes to improve the system accuracy. But the error caused by the misalignment angles and the scale factor error cannot be eliminated through dual-axis rotation modulation. And discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed the effect of calibration error during one modulated period and presented a new systematic self-calibration method for dual-axis rotation-modulating RLG-INS. Procedure for self-calibration of dual-axis rotation-modulating RLG-INS has been designed. The results of self-calibration simulation experiment proved that: this scheme can estimate all the errors in the calibration error model, the calibration precision of the inertial sensors scale factor error is less than 1ppm and the misalignment is less than 5″. These results have validated the systematic self-calibration method and proved its importance for accuracy improvement of dual -axis rotation inertial navigation system with mechanically dithered ring laser gyroscope.

  8. Sensors and Automated Analyzers for Radionuclides

    International Nuclear Information System (INIS)

    Grate, Jay W.; Egorov, Oleg B.

    2003-01-01

    The production of nuclear weapons materials has generated large quantities of nuclear waste and significant environmental contamination. We have developed new, rapid, automated methods for determination of radionuclides using sequential injection methodologies to automate extraction chromatographic separations, with on-line flow-through scintillation counting for real time detection. This work has progressed in two main areas: radionuclide sensors for water monitoring and automated radiochemical analyzers for monitoring nuclear waste processing operations. Radionuclide sensors have been developed that collect and concentrate radionuclides in preconcentrating minicolumns with dual functionality: chemical selectivity for radionuclide capture and scintillation for signal output. These sensors can detect pertechnetate to below regulatory levels and have been engineered into a prototype for field testing. A fully automated process monitor has been developed for total technetium in nuclear waste streams. This instrument performs sample acidification, speciation adjustment, separation and detection in fifteen minutes or less

  9. Dual Entwining Structures and Dual Entwined Modules

    OpenAIRE

    Abuhlail, Jawad Y.

    2003-01-01

    In this note we introduce and investigate the concepts of dual entwining structures and dual entwined modules. This generalizes the concepts of dual Doi-Koppinen structures and dual Doi-Koppinen modules introduced (in the infinite case over rings) by the author is his dissertation.

  10. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    Directory of Open Access Journals (Sweden)

    Pottier E.

    2010-06-01

    Full Text Available SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height

  11. Mixed error compensation in a heterodyne interferometer using the iterated dual-EKF algorithm

    International Nuclear Information System (INIS)

    Lee, Woo Ram; Kim, Chang Rai; You, Kwan Ho

    2010-01-01

    The heterodyne laser interferometer has been widely used in the field of precise measurements. The limited measurement accuracy of a heterodyne laser interferometer arises from the periodic nonlinearity caused by non-ideal laser sources and imperfect optical components. In this paper, the iterated dual-EKF algorithm is used to compensate for the error caused by nonlinearity and external noise. With the iterated dual-EKF algorithm, the weight filter estimates the parameter uncertainties in the state equation caused by nonlinearity errors and has a high convergence rate of weight values due to the iteration process. To verify the performance of the proposed compensation algorithm, we present experimental results obtained by using the iterated dual-EKF algorithm and compare them with the results obtained by using a capacitance displacement sensor.

  12. Mixed error compensation in a heterodyne interferometer using the iterated dual-EKF algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woo Ram; Kim, Chang Rai; You, Kwan Ho [Sungkyunkwan University, Suwon (Korea, Republic of)

    2010-10-15

    The heterodyne laser interferometer has been widely used in the field of precise measurements. The limited measurement accuracy of a heterodyne laser interferometer arises from the periodic nonlinearity caused by non-ideal laser sources and imperfect optical components. In this paper, the iterated dual-EKF algorithm is used to compensate for the error caused by nonlinearity and external noise. With the iterated dual-EKF algorithm, the weight filter estimates the parameter uncertainties in the state equation caused by nonlinearity errors and has a high convergence rate of weight values due to the iteration process. To verify the performance of the proposed compensation algorithm, we present experimental results obtained by using the iterated dual-EKF algorithm and compare them with the results obtained by using a capacitance displacement sensor.

  13. Inverse modeling of rainfall infiltration with a dual permeability approach using different matrix-fracture coupling variants.

    Science.gov (United States)

    Blöcher, Johanna; Kuraz, Michal

    2017-04-01

    In this contribution we propose implementations of the dual permeability model with different inter-domain exchange descriptions and metaheuristic optimization algorithms for parameter identification and mesh optimization. We compare variants of the coupling term with different numbers of parameters to test if a reduction of parameters is feasible. This can reduce parameter uncertainty in inverse modeling, but also allow for different conceptual models of the domain and matrix coupling. The different variants of the dual permeability model are implemented in the open-source objective library DRUtES written in FORTRAN 2003/2008 in 1D and 2D. For parameter identification we use adaptations of the particle swarm optimization (PSO) and Teaching-learning-based optimization (TLBO), which are population-based metaheuristics with different learning strategies. These are high-level stochastic-based search algorithms that don't require gradient information or a convex search space. Despite increasing computing power and parallel processing, an overly fine mesh is not feasible for parameter identification. This creates the need to find a mesh that optimizes both accuracy and simulation time. We use a bi-objective PSO algorithm to generate a Pareto front of optimal meshes to account for both objectives. The dual permeability model and the optimization algorithms were tested on virtual data and field TDR sensor readings. The TDR sensor readings showed a very steep increase during rapid rainfall events and a subsequent steep decrease. This was theorized to be an effect of artificial macroporous envelopes surrounding TDR sensors creating an anomalous region with distinct local soil hydraulic properties. One of our objectives is to test how well the dual permeability model can describe this infiltration behavior and what coupling term would be most suitable.

  14. Disturbance observer-based control of a dual-output LLC converter for solid-state lighting applications

    NARCIS (Netherlands)

    Roes, M.G.L.; Duarte, J.L.; Hendrix, M.A.M.

    2011-01-01

    Feedback sensor isolation is often an expensive necessity in power converters, for reasons of safety and electromagnetic compatibility. A disturbance observer-based control strategy for a dual-output resonant converter is proposed to overcome this problem. Current control of two LED loads is

  15. Disturbance observer-based control of a dual output LLC converter for solid state lighting applications

    NARCIS (Netherlands)

    Roes, M.G.L.; Duarte, J.L.; Hendrix, M.A.M.

    2010-01-01

    Feedback sensor isolation is often an expensive necessity in power converters, for reasons of safety and electromagnetic compatibility. A disturbance observer-based control strategy for a dual-output resonant converter is proposed to overcome this problem. Current control of two LED loads is

  16. eZinCh-2: a versatile, genetically-encoded FRET sensor for cytosolic and intra-organelle Zn2+ imaging

    NARCIS (Netherlands)

    Hessels, A.M.; Chabosseau, P.; Bakker, M.H.; Engelen, W.; Rutter, G.A.; Taylor, K.M.; Merkx, M.

    2015-01-01

    Zn2+ plays essential and diverse roles in numerous cellular processes. To get a better understanding of intracellular Zn2+ homeostasis and the putative signaling role of Zn2+, various fluorescent sensors have been developed that allow monitoring of Zn2+ concentrations in single living cells in real

  17. Smart Drug Delivery System-Inspired Enzyme-Linked Immunosorbent Assay Based on Fluorescence Resonance Energy Transfer and Allochroic Effect Induced Dual-Modal Colorimetric and Fluorescent Detection.

    Science.gov (United States)

    Miao, Luyang; Zhu, Chengzhou; Jiao, Lei; Li, He; Du, Dan; Lin, Yuehe; Wei, Qin

    2018-02-06

    Numerous analytical techniques have been undertaken for the detection of protein biomarkers because of their extensive and significant applications in clinical diagnosis, whereas there are few strategies to develop dual-readout immunosensors to achieve more accurate results. To the best of our knowledge, inspired by smart drug delivery system (DDS), a novel pH-responsive modified enzyme-linked immunosorbent assay (ELISA) was innovatively developed for the first time, realizing dual-modal colorimetric and fluorescent detection of cardiac troponin I (cTnI). Curcumin (CUR) was elaborately selected as a reporter molecule, which played the same role of drugs in DDS based on the following considerations: (1) CUR can be used as a kind of pH indicator by the inherited allochroic effect induced by basic pH value; (2) the fluorescence of CUR can be quenched by certain nanocarriers as the acceptor because of the occurrence of fluorescence resonance energy transfer (FRET), while recovered by the stimuli of basic pH value, which can produce "signal-on" fluorescence detection. Three-dimensional MoS 2 nanoflowers (3D-MoS 2 NFs) were employed in immobilizing CUR to constitute a nanoprobe for the determination of cTnI by virtue of good biocompatibility, high absorption capacity, and fluorescence quench efficiency toward CUR. The proposed DDS-inspired ELISA offered dual-modal colorimetric and fluorescent detection of cTnI, thereby meeting the reliable and precise analysis requirements. We believe that the developed dual-readout ELISA will create a new avenue and bring innovative inspirations for biological detections.

  18. Wearable-Sensor-Based Classification Models of Faller Status in Older Adults.

    Directory of Open Access Journals (Sweden)

    Jennifer Howcroft

    Full Text Available Wearable sensors have potential for quantitative, gait-based, point-of-care fall risk assessment that can be easily and quickly implemented in clinical-care and older-adult living environments. This investigation generated models for wearable-sensor based fall-risk classification in older adults and identified the optimal sensor type, location, combination, and modelling method; for walking with and without a cognitive load task. A convenience sample of 100 older individuals (75.5 ± 6.7 years; 76 non-fallers, 24 fallers based on 6 month retrospective fall occurrence walked 7.62 m under single-task and dual-task conditions while wearing pressure-sensing insoles and tri-axial accelerometers at the head, pelvis, and left and right shanks. Participants also completed the Activities-specific Balance Confidence scale, Community Health Activities Model Program for Seniors questionnaire, six minute walk test, and ranked their fear of falling. Fall risk classification models were assessed for all sensor combinations and three model types: multi-layer perceptron neural network, naïve Bayesian, and support vector machine. The best performing model was a multi-layer perceptron neural network with input parameters from pressure-sensing insoles and head, pelvis, and left shank accelerometers (accuracy = 84%, F1 score = 0.600, MCC score = 0.521. Head sensor-based models had the best performance of the single-sensor models for single-task gait assessment. Single-task gait assessment models outperformed models based on dual-task walking or clinical assessment data. Support vector machines and neural networks were the best modelling technique for fall risk classification. Fall risk classification models developed for point-of-care environments should be developed using support vector machines and neural networks, with a multi-sensor single-task gait assessment.

  19. Micro packaged MEMS pressure sensor for intracranial pressure measurement

    International Nuclear Information System (INIS)

    Liu Xiong; Yao Yan; Ma Jiahao; Zhang Zhaohua; Zhang Yanhang; Wang Qian; Ren Tianling

    2015-01-01

    This paper presents a micro packaged MEMS pressure sensor for intracranial pressure measurement which belongs to BioMEMS. It can be used in lumbar puncture surgery to measure intracranial pressure. Miniaturization is key for lumbar puncture surgery because the sensor must be small enough to allow it be placed in the reagent chamber of the lumbar puncture needle. The size of the sensor is decided by the size of the sensor chip and package. Our sensor chip is based on silicon piezoresistive effect and the size is 400 × 400 μm 2 . It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. In terms of package, the traditional dual in-line package obviously could not match the size need, the minimal size of recently reported MEMS-based intracranial pressure sensors after packaging is 10 × 10 mm 2 . In this work, we are the first to introduce a quad flat no-lead package as the package form of piezoresistive intracranial pressure sensors, the whole size of the sensor is minimized to only 3 × 3 mm 2 . Considering the liquid measurement environment, the sensor is gummed and waterproof performance is tested; the sensitivity of the sensor is 0.9 × 10 −2 mV/kPa. (paper)

  20. Dual functional extracellular recording using a light-addressable potentiometric sensor for bitter signal transduction.

    Science.gov (United States)

    Du, Liping; Wang, Jian; Chen, Wei; Zhao, Luhang; Wu, Chunsheng; Wang, Ping

    2018-08-31

    This paper presents a dual functional extracellular recording biosensor based on a light-addressable potentiometric sensor (LAPS). The design and fabrication of this biosensor make it possible to record both extracellular membrane potential changes and ATP release from a single taste bud cell for the first time. For detecting ATP release, LAPS chip was functionalized with ATP-sensitive DNA aptamer by covalent immobilization. Taste bud cells isolated from rat were cultured on LAPS surface. When the desired single taste bud cell was illuminated by modulated light, ATP release from single taste bud cells can be measured by recording the shifts of bias voltage-photocurrent curves (I-V curves) when the LAPS chip is working in discrete mode. On the other hand, extracellular membrane potential changes can be monitored by recording the fluctuation of LAPS photocurrent when the LAPS chip is working in continuous mode. The results show this biosensor can effectively record the enhancive effect of the bitter substance and inhibitory effect of the carbenoxolone (CBX) on the extracellular membrane potential changes and ATP release of single taste bud cells. In addition, the inhibitory effect of CBX also confirms LAPS extracellular recordings are originated from bitter signal transduction. It is proved this biosensor is suitable for extracellular recording of ATP release and membrane potential changes of single taste bud cells. It is suggested this biosensor could be applied to investigating taste signal transduction at the single-cell level as well as applied to other types of cells which have similar functions to taste bud cells. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Photoplethysmographic sensors for perfusion measurements in spinal cord tissue

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J P; Kyriacou, P A, E-mail: Justin.Phillips.1@city.ac.uk [School of Engineering and Mathematical Sciences, City University London, EC1V 0HB (United Kingdom)

    2011-08-17

    Sensors for recording photoplethysmographic signals from the nervous tissue of the spinal cord are described. The purpose of these sensors is to establish whether perfusion is compromised in various states of injury which occur in certain animal models of spinal cord injury, for example compression injury. Various measures of perfusion are applicable such as the amplitude of the photoplethysmograph signal and the oxygen saturation, measured using a dual wavelength configuration. Signals are usually compared to baseline measurements made in uninjured subjects. This paper describes two types of probe, one based on optical fibres, and one in which optotes are placed in direct contact with the tissue surface. Results from a study based on a compression model utilising a fibreoptic sensor are presented.

  2. Dual Comb Unit High-g Accelerometer Based on CMOS-MEMS Technology

    Directory of Open Access Journals (Sweden)

    Mehrdad Mottaghi

    2009-04-01

    Full Text Available In this paper a capacitive based high-g accelerometer with superior level of sensitivity is presented. It takes advantage of dual comb unit configuration and surface micromachining fabrication process. All aspects of mechanical design such as sensor structure, modal analysis, energy dissipations, dynamic response and stresses in moving structure as well as anchors are described. Electrical circuit based on CMOS technology and its output signal is presented. Fabrication process and packaging are also discussed. The proposed sensor can endure impact loads up to 120,000 g (g = 9.81 m.s-2 and achieves 16.75 µV.g-1 sensitivity with 5 V bridge excitation voltage. Main resonant frequency of structure is found to be 42.4 kHz. Intended applications of suggested sensor include military and aerospace industries as well as field of impact engineering.

  3. Imaging Intracellular pH in Live Cells with a Genetically-Encoded Red Fluorescent Protein Sensor

    OpenAIRE

    Tantama, Mathew; Hung, Yin Pun; Yellen, Gary

    2011-01-01

    Intracellular pH affects protein structure and function, and proton gradients underlie the function of organelles such as lysosomes and mitochondria. We engineered a genetically-encoded pH sensor by mutagenesis of the red fluorescent protein mKeima, providing a new tool to image intracellular pH in live cells. This sensor, named pHRed, is the first ratiometric, single-protein red fluorescent sensor of pH. Fluorescence emission of pHRed peaks at 610 nm while exhibiting dual excitation peaks at...

  4. Bacterially produced Pt-GFP as ratiometric dual-excitation sensor for in planta mapping of leaf apoplastic pH in intact Avena sativa and Vicia faba.

    Science.gov (United States)

    Geilfus, Christoph-Martin; Mühling, Karl H; Kaiser, Hartmut; Plieth, Christoph

    2014-01-01

    Ratiometric analysis with H(+)-sensitive fluorescent sensors is a suitable approach for monitoring apoplastic pH dynamics. For the acidic range, the acidotropic dual-excitation dye Oregon Green 488 is an excellent pH sensor. Long lasting (hours) recordings of apoplastic pH in the near neutral range, however, are more problematic because suitable pH indicators that combine a good pH responsiveness at a near neutral pH with a high photostability are lacking. The fluorescent pH reporter protein from Ptilosarcus gurneyi (Pt-GFP) comprises both properties. But, as a genetically encoded indicator and expressed by the plant itself, it can be used almost exclusively in readily transformed plants. In this study we present a novel approach and use purified recombinant indicators for measuring ion concentrations in the apoplast of crop plants such as Vicia faba L. and Avena sativa L. Pt-GFP was purified using a bacterial expression system and subsequently loaded through stomata into the leaf apoplast of intact plants. Imaging verified the apoplastic localization of Pt-GFP and excluded its presence in the symplast. The pH-dependent emission signal stood out clearly from the background. PtGFP is highly photostable, allowing ratiometric measurements over hours. By using this approach, a chloride-induced alkalinizations of the apoplast was demonstrated for the first in oat. Pt-GFP appears to be an excellent sensor for the quantification of leaf apoplastic pH in the neutral range. The presented approach encourages to also use other genetically encoded biosensors for spatiotemporal mapping of apoplastic ion dynamics.

  5. A Dual-Sensing Receptor Confers Robust Cellular Homeostasis

    Directory of Open Access Journals (Sweden)

    Hannah Schramke

    2016-06-01

    Full Text Available Cells have evolved diverse mechanisms that maintain intracellular homeostasis in fluctuating environments. In bacteria, control is often exerted by bifunctional receptors acting as both kinase and phosphatase to regulate gene expression, a design known to provide robustness against noise. Yet how such antagonistic enzymatic activities are balanced as a function of environmental change remains poorly understood. We find that the bifunctional receptor that regulates K+ uptake in Escherichia coli is a dual sensor, which modulates its autokinase and phosphatase activities in response to both extracellular and intracellular K+ concentration. Using mathematical modeling, we show that dual sensing is a superior strategy for ensuring homeostasis when both the supply of and demand for a limiting resource fluctuate. By engineering standards, this molecular control system displays a strikingly high degree of functional integration, providing a reference for the vast numbers of receptors for which the sensing strategy remains elusive.

  6. FRET measurements of kinesin neck orientation reveal a structural basis for processivity and asymmetry.

    Science.gov (United States)

    Martin, Douglas S; Fathi, Reza; Mitchison, Timothy J; Gelles, Jeff

    2010-03-23

    As the smallest and simplest motor enzymes, kinesins have served as the prototype for understanding the relationship between protein structure and mechanochemical function of enzymes in this class. Conventional kinesin (kinesin-1) is a motor enzyme that transports cargo toward the plus end of microtubules by a processive, asymmetric hand-over-hand mechanism. The coiled-coil neck domain, which connects the two kinesin motor domains, contributes to kinesin processivity (the ability to take many steps in a row) and is proposed to be a key determinant of the asymmetry in the kinesin mechanism. While previous studies have defined the orientation and position of microtubule-bound kinesin motor domains, the disposition of the neck coiled-coil remains uncertain. We determined the neck coiled-coil orientation using a multidonor fluorescence resonance energy transfer (FRET) technique to measure distances between microtubules and bound kinesin molecules. Microtubules were labeled with a new fluorescent taxol donor, TAMRA-X-taxol, and kinesin derivatives with an acceptor fluorophore attached at positions on the motor and neck coiled-coil domains were used to reconstruct the positions and orientations of the domains. FRET measurements to positions on the motor domain were largely consistent with the domain orientation determined in previous studies, validating the technique. Measurements to positions on the neck coiled-coil were inconsistent with a radial orientation and instead demonstrated that the neck coiled-coil is parallel to the microtubule surface. The measured orientation provides a structural explanation for how neck surface residues enhance processivity and suggests a simple hypothesis for the origin of kinesin step asymmetry and "limping."

  7. Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

    Science.gov (United States)

    Lee, Jin-Hyuk; Kim, Dae-Hyun

    2014-10-01

    A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

  8. Monitoring Poisson's ratio of glass fiber reinforced composites as damage index using biaxial Fiber Bragg Grating sensors

    OpenAIRE

    Yılmaz, Çağatay; Yilmaz, Cagatay; Akalın, Çağdaş; Akalin, Cagdas; Kocaman, Esat Selim; Suleman, A.; Yıldız, Mehmet; Yildiz, Mehmet

    2016-01-01

    Damage accumulation in Glass Fiber Reinforced Polymer (GFRP) composites is monitored based on Poisson's ratio measurements for three different fiber stacking sequences subjected to both quasi-static and quasi-static cyclic tensile loadings. The sensor systems utilized include a dual-extensometer, a biaxial strain gage and a novel embedded-biaxial Fiber Bragg Grating (FBG) sensor. These sensors are used concurrently to measure biaxial strain whereby the evolution of Poisson's ratio as a functi...

  9. FRET study of membrane proteins: determination of the tilt and orientation of the N-terminal domain of M13 major coat protein

    NARCIS (Netherlands)

    Nazarov, P.V.; Koehorst, R.B.M.; Vos, W.L.; Apanasovich, V.V.; Hemminga, M.A.

    2007-01-01

    A formalism for membrane protein structure determination was developed. This method is based on steady-state FRET data and information about the position of the fluorescence maxima on site-directed fluorescent labeled proteins in combination with global data analysis utilizing simulation-based

  10. The Conformational Dynamics of Cas9 Governing DNA Cleavage Are Revealed by Single-Molecule FRET

    Directory of Open Access Journals (Sweden)

    Mengyi Yang

    2018-01-01

    Full Text Available Summary: Off-target binding and cleavage by Cas9 pose major challenges in its application. How the conformational dynamics of Cas9 govern its nuclease activity under on- and off-target conditions remains largely unknown. Here, using intra-molecular single-molecule fluorescence resonance energy transfer measurements, we revealed that Cas9 in apo, sgRNA-bound, and dsDNA/sgRNA-bound forms spontaneously transits among three major conformational states, mainly reflecting significant conformational mobility of the catalytic HNH domain. We also uncovered surprising long-range allosteric communication between the HNH domain and the RNA/DNA heteroduplex at the PAM-distal end to ensure correct positioning of the catalytic site, which demonstrated that a unique proofreading mechanism served as the last checkpoint before DNA cleavage. Several Cas9 residues were likely to mediate the allosteric communication and proofreading step. Modulating interactions between Cas9 and heteroduplex at the PAM-distal end by introducing mutations on these sites provides an alternative route to improve and optimize the CRISPR/Cas9 toolbox. : Yang et al. revealed significant conformational dynamics of Cas9 at global and local scales using single-molecule FRET. They uncovered surprising long-range allosteric communication between the HNH nuclease domain and the RNA/DNA heteroduplex at the PAM-distal end that serves as a proofreading checkpoint to govern the nuclease activity and specificity of Cas9. Keywords: CRISPR, Cas9, single-molecule, FRET, conformational dynamics, proofreading, off-target, allosteric communication, genome editing

  11. Tumor-specific detection of an optically targeted antibody combined with a quencher-conjugated neutravidin "quencher-chaser": a dual "quench and chase" strategy to improve target to nontarget ratios for molecular imaging of cancer.

    Science.gov (United States)

    Ogawa, Mikako; Kosaka, Nobuyuki; Choyke, Peter L; Kobayashi, Hisataka

    2009-01-01

    In vivo molecular cancer imaging with monoclonal antibodies has great potential not only for cancer detection, but also for cancer characterization. However, the prolonged retention of intravenously injected antibody in the blood causes low target tumor-to-background ratio (TBR). Avidin has been used as a "chase" to clear the unbound, circulating biotinylated antibody and decrease the background signal. Here, we utilize a combined approach of a fluorescence resonance energy transfer (FRET) quenched antibody with an "avidin chase" to increase TBR. Trastuzumab, a humanized monoclonal antibody against human epidermal growth factor receptor type 2 (HER2), was biotinylated and conjugated with the near-infrared (NIR) fluorophore Alexa680 to synthesize Tra-Alexa680-biotin. Next, the FRET quencher, QSY-21, was conjugated to avidin, neutravidin (nAv), or streptavidin (sAv), thus creating Av-QSY21, nAv-QSY21, or sAv-QSY21 as "chasers". The fluorescence was quenched in vitro by binding Tra-Alexa680-biotin to Av-QSY21, nAv-QSY21, or sAv-QSY21. To evaluate if the injection of quencher-conjugated avidin derivatives can improve target TBR by using a dual "quench and chase" strategy, both target (3T3/HER2+) and nontarget (Balb3T3/ZsGreen) tumor-bearing mice were employed. The "FRET quench" effect induced by all the QSY21 avidin-based conjugates reduced but did not totally eliminate background signal from the blood pool. The addition of nAv-QSY21 administration increased target TBR mainly because of the "chase" effect where unbound conjugated antibody was preferentially cleared to the liver. The relatively slow clearance of unbound nAv-QSY21 leads to further reductions in background signal by leaking out of the vascular space and binding to unbound antibodies in the extravascular space of tumors, resulting in decreased nontarget tumor-to-background ratios but increased target TBR due to the "FRET quench" effect, because target-bound antibodies were internalized and could not bind

  12. Design of cross-sensitive temperature and strain sensor based on sampled fiber grating

    Directory of Open Access Journals (Sweden)

    Zhang Xiaohang

    2017-02-01

    Full Text Available In this paper,a cross-sensitive temperature and strain sensor based on sampled fiber grating is designed.Its temperature measurement range is -50-200℃,and the strain measurement rangeis 0-2 000 με.The characteristics of the sensor are obtained using simulation method.Utilizing SPSS software,we found the dual-parameter matrix equations of measurement of temperature and strain,and calibrated the four sensing coefficients of the matrix equations.

  13. A research on radiation calibration of high dynamic range based on the dual channel CMOS

    Science.gov (United States)

    Ma, Kai; Shi, Zhan; Pan, Xiaodong; Wang, Yongsheng; Wang, Jianghua

    2017-10-01

    The dual channel complementary metal-oxide semiconductor (CMOS) can get high dynamic range (HDR) image through extending the gray level of the image by using image fusion with high gain channel image and low gain channel image in a same frame. In the process of image fusion with dual channel, it adopts the coefficients of radiation response of a pixel from dual channel in a same frame, and then calculates the gray level of the pixel in the HDR image. For the coefficients of radiation response play a crucial role in image fusion, it has to find an effective method to acquire these parameters. In this article, it makes a research on radiation calibration of high dynamic range based on the dual channel CMOS, and designs an experiment to calibrate the coefficients of radiation response for the sensor it used. In the end, it applies these response parameters in the dual channel CMOS which calibrates, and verifies the correctness and feasibility of the method mentioned in this paper.

  14. A Novel Dual Traffic/Flash Flood Monitoring System Using Passive Infrared/Ultrasonic Sensors

    KAUST Repository

    Mousa, Mustafa

    2015-10-19

    Floods are the most common type of natural disaster, causing thousands of casualties every year. Among these events, urban flash floods are particularly deadly because of the short timescales on which they occur, and because of the high concentration of population in cities. Since most flash flood casualties are caused by a lack of information, it is critical to generate accurate and detailed warnings of flash floods. However, deploying an infrastructure that solely monitor flash floods makes little economic sense, since the average periodicity of catastrophic flash floods exceeds the lifetime of a typical sensor network. To address this issue, we propose a new sensing device that can simultaneously monitor urban flash floods and another phenomenon of interest (traffic congestion on the present case). This sensing device is based on the combination of an ultrasonic rangefinder with one or multiple remote temperature sensors. We show an implementation of this device, and illustrate its performance in both traffic flow and flash flood sensing. Field data shows that the sensor can detect vehicles with a 99% accuracy, in addition to estimating their speed and classifying them in function of their length. The same sensor can also monitor urban water levels with an accuracy of less than 2 cm. Two of the sensors have been deployed in a flood prone area, where they captured the only (minor) flash flood that occurred over the one-year test period, with no false detection, and an agreement in the estimated water level estimate (during the flash flood event) of about 2 cm.

  15. A Novel Dual Traffic/Flash Flood Monitoring System Using Passive Infrared/Ultrasonic Sensors

    KAUST Repository

    Mousa, Mustafa; Odat, Enas M.; Claudel, Christian

    2015-01-01

    Floods are the most common type of natural disaster, causing thousands of casualties every year. Among these events, urban flash floods are particularly deadly because of the short timescales on which they occur, and because of the high concentration of population in cities. Since most flash flood casualties are caused by a lack of information, it is critical to generate accurate and detailed warnings of flash floods. However, deploying an infrastructure that solely monitor flash floods makes little economic sense, since the average periodicity of catastrophic flash floods exceeds the lifetime of a typical sensor network. To address this issue, we propose a new sensing device that can simultaneously monitor urban flash floods and another phenomenon of interest (traffic congestion on the present case). This sensing device is based on the combination of an ultrasonic rangefinder with one or multiple remote temperature sensors. We show an implementation of this device, and illustrate its performance in both traffic flow and flash flood sensing. Field data shows that the sensor can detect vehicles with a 99% accuracy, in addition to estimating their speed and classifying them in function of their length. The same sensor can also monitor urban water levels with an accuracy of less than 2 cm. Two of the sensors have been deployed in a flood prone area, where they captured the only (minor) flash flood that occurred over the one-year test period, with no false detection, and an agreement in the estimated water level estimate (during the flash flood event) of about 2 cm.

  16. Fluorescence Resonance Energy Transfer in Polydiacetylene Liposomes

    Science.gov (United States)

    Li, Xuelian; Matthews, Shelton; Kohli, Punit

    2009-01-01

    Conjugated polydiacetylene (PDA) possessing stimuli-responsive properties has been intensively investigated for developing efficient sensors. We report here fluorescence resonance energy transfer (FRET) in liposomes synthesized using different molar ratios of dansyl-tagged diacetylene and diacetylene–carboxylic acid monomers. Photopolymerization of diacetylene resulted in cross-linked PDA liposomes. We used steady-state electronic absorption, emission, and fluorescence anisotropy (FA) analysis to characterize the thermal-induced FRET between dansyl fluorophores (donor) and PDA (acceptor). We found that the monomer ratio of acceptor to donor (Rad) and length of linkers (functional part that connects dansyl fluorophores to the diacetylene group in the monomer) strongly affected FRET. For Rad = 10 000, the acceptor emission intensity was amplified by more than 18 times when the liposome solution was heated from 298 to 338 K. A decrease in Rad resulted in diminished acceptor emission amplification. This was primarily attributed to lower FRET efficiency between donors and acceptors and a higher background signal. We also found that the FRET amplification of PDA emissions after heating the solution was much higher when dansyl was linked to diacetylene through longer and flexible linkers than through shorter linkers. We attributed this to insertion of dansyl in the bilayer of the liposomes, which led to an increased dansyl quantum yield and a higher interaction of multiple acceptors with limited available donors. This was not the case for shorter and more rigid linkers where PDA amplification was much smaller. The present studies aim at enhancing our understanding of FRET between fluorophores and PDA-based conjugated liposomes. Furthermore, receptor tagged onto PDA liposomes can interact with ligands present on proteins, enzymes, and cells, which will produce emission sensing signal. Therefore, using the present approach, there exist opportunities for designing FRET

  17. Time resolved amplified FRET identifies protein kinase B activation state as a marker for poor prognosis in clear cell renal cell carcinoma

    Directory of Open Access Journals (Sweden)

    James Miles

    2017-12-01

    General significance: The quantitative imaging technology based on Amplified-FRET can rapidly analyse protein activation states and molecular interactions. It could be used for prognosis and assess drug function during the early cycles of chemotherapy. It enables evaluation of clinical efficiency of personalised cancer treatment.

  18. Dual reference point temperature interrogating method for distributed temperature sensor

    International Nuclear Information System (INIS)

    Ma, Xin; Ju, Fang; Chang, Jun; Wang, Weijie; Wang, Zongliang

    2013-01-01

    A novel method based on dual temperature reference points is presented to interrogate the temperature in a distributed temperature sensing (DTS) system. This new method is suitable to overcome deficiencies due to the impact of DC offsets and the gain difference in the two signal channels of the sensing system during temperature interrogation. Moreover, this method can in most cases avoid the need to calibrate the gain and DC offsets in the receiver, data acquisition and conversion. An improved temperature interrogation formula is presented and the experimental results show that this method can efficiently estimate the channel amplification and system DC offset, thus improving the system accuracy. (letter)

  19. Evaluation of pH-sensitive poly(β-amino ester)-graft-poly(ethylene glycol) and its usefulness as a pH-sensor and protein carrier.

    Science.gov (United States)

    Kim, Min Sang; Gao, Guang Hui; Kang, Seong Woo; Lee, Doo Sung

    2011-07-07

    In this study, some possible biomedical applications of a pH-sensitive and amphiphilic copolymer as a pH sensor and protein delivery system are reported. PAE-g-PEG was used as a pH-sensitive polymer that can exhibit a sharp pH-dependent transition. Various fluorescent dyes including pyrene and RITC can be used to label the pH-sensitive polymer PAE-g-PEG, which was evaluated for protein encapsulation. pH-sensing was possible by observing excimer formation of the labeled pyrene via pH-dependent expansion of the polymeric chain. Also, it was confirmed that FITC-BSA could be entrapped in RITC-labeled pH-sensitive micelles of PAE-g-PEG by FRET. As a result, PAE-g-PEG can be a pH sensor and carrier for protein delivery. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Temperature-referenced high-sensitivity point-probe optical fiber chem-sensors based on cladding etched fiber Bragg gratings

    OpenAIRE

    Zhou, Kaiming; Chen, Xianfeng F.; Zhang, Lin; Bennion, Ian

    2004-01-01

    Point-probe optical fiber chem-sensors have been implemented using cladding etched fiber Bragg gratings. The sensors possess refractive index sensing capability that can be utilized to measure chemical concentrations. The Bragg wavelength shift reaches 8 nm when the index of surrounding medium changes from 1.33 to 1.44, giving maximum sensitivity more than 10 times higher than that of previously reported devices. More importantly, the dual-grating configuration of the point-probe sensors offe...