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Sample records for fluorescence lifetime standards

  1. Standard reference for instrument response function in fluorescence lifetime measurements in visible and near infrared

    International Nuclear Information System (INIS)

    Chib, Rahul; Shah, Sunil; Gryczynski, Zygmunt; Fudala, Rafal; Borejdo, Julian; Gryczynski, Ignacy; Zelent, Bogumil; Corradini, Maria G; Ludescher, Richard D

    2016-01-01

    Allura red (AR) fluorophore, a common dye in the food industry, displays a broad emission spectrum in water (visible-to-near infrared region of the electromagnetic spectrum) and has a remarkably short fluorescence lifetime of about 10 ps. This short lifetime does not depend on the emission (observation) wavelength. We examined time responses of AR fluorescence across emission wavelengths from 550 nm to 750 nm and found that it is an ideal candidate for impulse response functions in fluorescence lifetime measurements. (technical note)

  2. Fluorescence lifetime based bioassays

    Science.gov (United States)

    Meyer-Almes, Franz-Josef

    2017-12-01

    Fluorescence lifetime (FLT) is a robust intrinsic property and material constant of fluorescent matter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery, medical diagnostics and basic biological research. This distinct trend was mainly driven by improved and meanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. The first one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second even more dynamic trend is the significant expansion of assay methods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.

  3. Fluorescence lifetime imaging of skin cancer

    Science.gov (United States)

    Patalay, Rakesh; Talbot, Clifford; Munro, Ian; Breunig, Hans Georg; König, Karsten; Alexandrov, Yuri; Warren, Sean; Neil, Mark A. A.; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Chris

    2011-03-01

    Fluorescence intensity imaging and fluorescence lifetime imaging microscopy (FLIM) using two photon microscopy (TPM) have been used to study tissue autofluorescence in ex vivo skin cancer samples. A commercially available system (DermaInspect®) was modified to collect fluorescence intensity and lifetimes in two spectral channels using time correlated single photon counting and depth-resolved steady state measurements of the fluorescence emission spectrum. Uniquely, image segmentation has been used to allow fluorescence lifetimes to be calculated for each cell. An analysis of lifetime values obtained from a range of pigmented and non-pigmented lesions will be presented.

  4. Three-dimensional fluorescence lifetime tomography

    International Nuclear Information System (INIS)

    Godavarty, Anuradha; Sevick-Muraca, Eva M.; Eppstein, Margaret J.

    2005-01-01

    Near-infrared fluorescence tomography using molecularly targeted lifetime-sensitive, fluorescent contrast agents have applications for early-stage cancer diagnostics. Yet, although the measurement of fluorescent lifetime imaging microscopy (FLIM) is extensively used in microscopy and spectroscopy applications, demonstration of fluorescence lifetime tomography for medical imaging is limited to two-dimensional studies. Herein, the feasibility of three-dimensional fluorescence-lifetime tomography on clinically relevant phantom volumes is established, using (i) a gain-modulated intensified charge coupled device (CCD) and modulated laser diode imaging system, (ii) two fluorescent contrast agents, e.g., Indocyanine green and 3-3'-Diethylthiatricarbocyanine iodide differing in their fluorescence lifetime by 0.62 ns, and (iii) a two stage approximate extended Kalman filter reconstruction algorithm. Fluorescence measurements of phase and amplitude were acquired on the phantom surface under different target to background fluorescence absorption (70:1, 100:1) and fluorescence lifetime (1:1, 2.1:1) contrasts at target depths of 1.4-2 cm. The Bayesian tomography algorithm was employed to obtain three-dimensional images of lifetime and absorption owing to the fluorophores

  5. Fluorescence lifetime imaging using light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Gordon T; Munro, Ian; Poher, Vincent; French, Paul M W; Neil, Mark A A [Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Elson, Daniel S [Institute of Biomedical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Hares, Jonathan D [Kentech Instruments Ltd, Unit 9, Hall Farm Workshops, South Moreton, Didcot, Oxfordshire, OX11 9AG (United Kingdom)], E-mail: gordon.kennedy@imperial.ac.uk

    2008-05-07

    We demonstrate flexible use of low cost, high-power light emitting diodes as illumination sources for fluorescence lifetime imaging (FLIM). Both time-domain and frequency-domain techniques have been implemented at wavelengths spanning the range 450-640 nm. Additionally, we demonstrate optically sectioned fluorescence lifetime imaging by combining structured illumination with frequency-domain FLIM.

  6. Quantitative analysis of fluorescence lifetime measurements of the macula using the fluorescence lifetime imaging ophthalmoscope in healthy subjects.

    Science.gov (United States)

    Dysli, Chantal; Quellec, Gwénolé; Abegg, Mathias; Menke, Marcel N; Wolf-Schnurrbusch, Ute; Kowal, Jens; Blatz, Johannes; La Schiazza, Olivier; Leichtle, Alexander B; Wolf, Sebastian; Zinkernagel, Martin S

    2014-04-03

    Fundus autofluorescence (FAF) cannot only be characterized by the intensity or the emission spectrum, but also by its lifetime. As the lifetime of a fluorescent molecule is sensitive to its local microenvironment, this technique may provide more information than fundus autofluorescence imaging. We report here the characteristics and repeatability of FAF lifetime measurements of the human macula using a new fluorescence lifetime imaging ophthalmoscope (FLIO). A total of 31 healthy phakic subjects were included in this study with an age range from 22 to 61 years. For image acquisition, a fluorescence lifetime ophthalmoscope based on a Heidelberg Engineering Spectralis system was used. Fluorescence lifetime maps of the retina were recorded in a short- (498-560 nm) and a long- (560-720 nm) spectral channel. For quantification of fluorescence lifetimes a standard ETDRS grid was used. Mean fluorescence lifetimes were shortest in the fovea, with 208 picoseconds for the short-spectral channel and 239 picoseconds for the long-spectral channel, respectively. Fluorescence lifetimes increased from the central area to the outer ring of the ETDRS grid. The test-retest reliability of FLIO was very high for all ETDRS areas (Spearman's ρ = 0.80 for the short- and 0.97 for the long-spectral channel, P macula in healthy subjects. By using a custom-built software, we were able to quantify fluorescence lifetimes within the ETDRS grid. Establishing a clinically accessible standard against which to measure FAF lifetimes within the retina is a prerequisite for future studies in retinal disease.

  7. Remote UV Fluorescence Lifetime Spectrometer, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this project is to develop, demonstrate, and deliver to NASA an innovative, portable, and power efficient Remote UV Fluorescence Lifetime Spectrometer...

  8. Fluorescence lifetime measurement of radical ions

    International Nuclear Information System (INIS)

    Ichinose, Nobuyuki; Kinugasa, Jun-ichiro; Hagiri, Masahide; Nakayama, Toshihiro; Murakami, Hiroshi; Kishimoto, Maki; Daido, Hiroyuki

    2004-01-01

    One-photonic excitation of a charge transfer complex of hexamethoxybenzene (HMB) and nitrosonium tetrafluoroborate (NO + BF 4 - ) in acetonitrile afforded fluorescences emission from excited radical cation of HMB (HMB + *). Lifetime of the excited radical ion species was measured to be 7 ps by the pump-probe transient absorption technique. The lifetime was much shorter than that of free radical ion (63 ps), indicating the presence of an interaction between HMB + * and NO in the excited complex. (author)

  9. Time variation of fluorescence lifetime in enhanced cyan fluorescence protein

    International Nuclear Information System (INIS)

    Lee, Soonhyouk; Kim, Soo Yong; Park, Kyoungsook; Jeong, Jinyoung; Chung, Bong Hyun; Kim, Sok Won

    2010-01-01

    The lifetime variations of enhanced cyan fluorescence protein (ECFP) in relatively short integration time bins were studied via time-correlated single photon counting (TCSPC) measurement. We observed that minimum photon counts are necessary for the lifetime estimation to achieve a certain range of variance. The conditions to decrease the variance of lifetime were investigated and the channel width of the measurement of TCSPC data was found to be another important factor for the variance of lifetime. Though the lifetime of ECFP is best fit by a double exponential, a mono exponential fit for the same integration time is more stable. The results may be useful in the analysis of photophysical dynamics for ensemble molecules in short measurement time windows.

  10. Theoretical lifetimes and fluorescence yields for multiply-ionized fluorine

    International Nuclear Information System (INIS)

    Tunnell, T.W.; Can, C.; Bhalla, C.P.

    1978-01-01

    Theoretical lifetimes and multiplet partial fluorescence yields for various fluorine ions with a single K-shell vacancy were calculated. For few-electron systems, the lifetimes and line fluorescence yields were computed in the intermediate coupling scheme with the inclusion of the effects arising from configuration interactions. 6 references

  11. Fluorescence lifetime assays: current advances and applications in drug discovery.

    Science.gov (United States)

    Pritz, Stephan; Doering, Klaus; Woelcke, Julian; Hassiepen, Ulrich

    2011-06-01

    Fluorescence lifetime assays complement the portfolio of established assay formats available in drug discovery, particularly with the recent advances in microplate readers and the commercial availability of novel fluorescent labels. Fluorescence lifetime assists in lowering complexity of compound screening assays, affording a modular, toolbox-like approach to assay development and yielding robust homogeneous assays. To date, materials and procedures have been reported for biochemical assays on proteases, as well as on protein kinases and phosphatases. This article gives an overview of two assay families, distinguished by the origin of the fluorescence signal modulation. The pharmaceutical industry demands techniques with a robust, integrated compound profiling process and short turnaround times. Fluorescence lifetime assays have already helped the drug discovery field, in this sense, by enhancing productivity during the hit-to-lead and lead optimization phases. Future work will focus on covering other biochemical molecular modifications by investigating the detailed photo-physical mechanisms underlying the fluorescence signal.

  12. Fluorescence lifetime imaging of oxygen in dental biofilm

    Science.gov (United States)

    Gerritsen, Hans C.; de Grauw, Cees J.

    2000-12-01

    Dental biofilm consists of micro-colonies of bacteria embedded in a matrix of polysaccharides and salivary proteins. pH and oxygen concentration are of great importance in dental biofilm. Both can be measured using fluorescence techniques. The imaging of dental biofilm is complicated by the thickness of the biofilms that can be up to several hundred micrometers thick. Here, we employed a combination of two-photon excitation microscopy with fluorescence lifetime imaging to quantify the oxygen concentration in dental biofilm. Collisional quenching of fluorescent probes by molecular oxygen leads to a reduction of the fluorescence lifetime of the probe. We employed this mechanism to measure the oxygen concentration distribution in dental biofilm by means of fluorescence lifetime imaging. Here, TRIS Ruthenium chloride hydrate was used as an oxygen probe. A calibration procedure on buffers was use to measure the lifetime response of this Ruthenium probe. The results are in agreement with the Stern-Volmer equation. A linear relation was found between the ratio of the unquenched and the quenched lifetime and the oxygen concentration. The biofilm fluorescence lifetime imaging results show a strong oxygen gradient at the buffer - biofilm interface and the average oxygen concentration in the biofilm amounted to 50 μM.

  13. Refractive index sensing using Fluorescence Lifetime Imaging (FLIM)

    International Nuclear Information System (INIS)

    Jones, Carolyn; Suhling, Klaus

    2006-01-01

    The fluorescence lifetime is a function of the refractive index of the fluorophore's environment, for example in the case of the biologically important green fluorescent protein (GFP). In order to address the question whether this effect can be exploited to image the local environment of specific proteins in cell biology, we need to determine the distance over which the fluorophore's lifetime is sensitive to the refractive index. To this end, we employ Fluorescence Lifetime Imaging (FLIM) of fluorescein in NaOH buffer at an interface. This approach allows us to map the fluorescence lifetime as a function of distance from a buffer/air and buffer/oil interface. Preliminary data show that the fluorescence lifetime of fluorescein increases near a buffer/air interface and decreases near a buffer/oil interface. The range over which this fluorescence lifetime change occurs is found to be of the order several μm which is consistent with a theoretical model based on the full width at half maximum of the emission spectrum proposed by Toptygin

  14. Fluorescence lifetime evaluation of whole soils from the Amazon rainforest.

    Science.gov (United States)

    Nicolodelli, Gustavo; Tadini, Amanda Maria; Nogueira, Marcelo Saito; Pratavieira, Sebastião; Mounier, Stephane; Huaman, Jose Luis Clabel; Dos Santos, Cléber Hilário; Montes, Célia Regina; Milori, Débora Marcondes Bastos Pereira

    2017-08-20

    Time-resolved fluorescence spectroscopy (TRFS) is a new tool that can be used to investigate processes of interaction between metal ions and organic matter (OM) in soils, providing a specific analysis of the structure and dynamics of macromolecules. To the best of our knowledge, there are no studies in the literature reporting the use of this technique applied to whole/non-fractionated soil samples, making it a potential method for use in future studies. This work describes the use of TRFS to evaluate the fluorescence lifetimes of OM of whole soils from the Amazon region. Analysis was made of pellets of soils from an oxisol-spodosol system, collected in São Gabriel da Cachoeira (Amazonas, Brazil). The fluorescence lifetimes in the oxisol-spodosol system were attributed to two different fluorophores. One was related to complexation of an OM fraction with metals, resulting in a shorter fluorophore lifetime. A short fluorescence lifetime (2-12 ns) could be associated with simpler structures of the OM, while a long lifetime (19-66 ns) was associated with more complex OM structures. This new TRFS technique for analysis of the fluorescence lifetime in whole soil samples complies with the principles of green chemistry.

  15. Clinical results of fluorescence lifetime imaging in ophthalmology

    Science.gov (United States)

    Schweitzer, D.; Quick, S.; Klemm, M.; Hammer, M.; Jentsch, S.; Dawczynski, J.; Becker, W.

    2009-07-01

    A laser scanner ophthalmoscope was developed for in vivo fluorescence lifetime measurements at the human retina. Measurements were performed in 30 degree fundus images. The fundus was excited by pulses of 75 ps (FWHM). The dynamic fluorescence was detected in two spectral channels K1(490-560nm), K2(560-700 nm) by time-correlated single photon counting. The decay of fluorescence was three-exponentially. Local and global alterations in lifetimes were found between healthy subjects and patients suffering from age-related macular degeneration, diabetic retinopathy, and vessel occlusion. The lifetimes T1, T2, and T3 in both channels are changed to longer values in AMD and diabetic retinopathy in comparison with healthy subjects. The lifetime T2 in K1 is most sensitive to metabolic alterations in branch arterial vessel occlusion.

  16. Fluorescence lifetime imaging microscopy using near-infrared contrast agents.

    Science.gov (United States)

    Nothdurft, R; Sarder, P; Bloch, S; Culver, J; Achilefu, S

    2012-08-01

    Although single-photon fluorescence lifetime imaging microscopy (FLIM) is widely used to image molecular processes using a wide range of excitation wavelengths, the captured emission of this technique is confined to the visible spectrum. Here, we explore the feasibility of utilizing near-infrared (NIR) fluorescent molecular probes with emission >700 nm for FLIM of live cells. The confocal microscope is equipped with a 785 nm laser diode, a red-enhanced photomultiplier tube, and a time-correlated single photon counting card. We demonstrate that our system reports the lifetime distributions of NIR fluorescent dyes, cypate and DTTCI, in cells. In cells labelled separately or jointly with these dyes, NIR FLIM successfully distinguishes their lifetimes, providing a method to sort different cell populations. In addition, lifetime distributions of cells co-incubated with these dyes allow estimate of the dyes' relative concentrations in complex cellular microenvironments. With the heightened interest in fluorescence lifetime-based small animal imaging using NIR fluorophores, this technique further serves as a bridge between in vitro spectroscopic characterization of new fluorophore lifetimes and in vivo tissue imaging. © 2012 The Author Journal of Microscopy © 2012 Royal Microscopical Society.

  17. Multiphoton fluorescence lifetime imaging of chemotherapy distribution in solid tumors

    Science.gov (United States)

    Carlson, Marjorie; Watson, Adrienne L.; Anderson, Leah; Largaespada, David A.; Provenzano, Paolo P.

    2017-11-01

    Doxorubicin is a commonly used chemotherapeutic employed to treat multiple human cancers, including numerous sarcomas and carcinomas. Furthermore, doxorubicin possesses strong fluorescent properties that make it an ideal reagent for modeling drug delivery by examining its distribution in cells and tissues. However, while doxorubicin fluorescence and lifetime have been imaged in live tissue, its behavior in archival samples that frequently result from drug and treatment studies in human and animal patients, and murine models of human cancer, has to date been largely unexplored. Here, we demonstrate imaging of doxorubicin intensity and lifetimes in archival formalin-fixed paraffin-embedded sections from mouse models of human cancer with multiphoton excitation and multiphoton fluorescence lifetime imaging microscopy (FLIM). Multiphoton excitation imaging reveals robust doxorubicin emission in tissue sections and captures spatial heterogeneity in cells and tissues. However, quantifying the amount of doxorubicin signal in distinct cell compartments, particularly the nucleus, often remains challenging due to strong signals in multiple compartments. The addition of FLIM analysis to display the spatial distribution of excited state lifetimes clearly distinguishes between signals in distinct compartments such as the cell nuclei versus cytoplasm and allows for quantification of doxorubicin signal in each compartment. Furthermore, we observed a shift in lifetime values in the nuclei of transformed cells versus nontransformed cells, suggesting a possible diagnostic role for doxorubicin lifetime imaging to distinguish normal versus transformed cells. Thus, data here demonstrate that multiphoton FLIM is a highly sensitive platform for imaging doxorubicin distribution in normal and diseased archival tissues.

  18. Mesh adaptation technique for Fourier-domain fluorescence lifetime imaging

    International Nuclear Information System (INIS)

    Soloviev, Vadim Y.

    2006-01-01

    A novel adaptive mesh technique in the Fourier domain is introduced for problems in fluorescence lifetime imaging. A dynamical adaptation of the three-dimensional scheme based on the finite volume formulation reduces computational time and balances the ill-posed nature of the inverse problem. Light propagation in the medium is modeled by the telegraph equation, while the lifetime reconstruction algorithm is derived from the Fredholm integral equation of the first kind. Stability and computational efficiency of the method are demonstrated by image reconstruction of two spherical fluorescent objects embedded in a tissue phantom

  19. Measuring and sorting cell populations expressing isospectral fluorescent proteins with different fluorescence lifetimes.

    Directory of Open Access Journals (Sweden)

    Bryan Sands

    Full Text Available Study of signal transduction in live cells benefits from the ability to visualize and quantify light emitted by fluorescent proteins (XFPs fused to different signaling proteins. However, because cell signaling proteins are often present in small numbers, and because the XFPs themselves are poor fluorophores, the amount of emitted light, and the observable signal in these studies, is often small. An XFP's fluorescence lifetime contains additional information about the immediate environment of the fluorophore that can augment the information from its weak light signal. Here, we constructed and expressed in Saccharomyces cerevisiae variants of Teal Fluorescent Protein (TFP and Citrine that were isospectral but had shorter fluorescence lifetimes, ∼ 1.5 ns vs ∼ 3 ns. We modified microscopic and flow cytometric instruments to measure fluorescence lifetimes in live cells. We developed digital hardware and a measure of lifetime called a "pseudophasor" that we could compute quickly enough to permit sorting by lifetime in flow. We used these abilities to sort mixtures of cells expressing TFP and the short-lifetime TFP variant into subpopulations that were respectively 97% and 94% pure. This work demonstrates the feasibility of using information about fluorescence lifetime to help quantify cell signaling in living cells at the high throughput provided by flow cytometry. Moreover, it demonstrates the feasibility of isolating and recovering subpopulations of cells with different XFP lifetimes for subsequent experimentation.

  20. Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations.

    Science.gov (United States)

    Hosny, Neveen A; Lee, David A; Knight, Martin M

    2012-01-01

    Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)(3)](2+), was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)(3)](2+) characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

  1. Two-dimensional fluorescence lifetime correlation spectroscopy. 2. Application.

    Science.gov (United States)

    Ishii, Kunihiko; Tahara, Tahei

    2013-10-03

    In the preceding article, we introduced the theoretical framework of two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS). In this article, we report the experimental implementation of 2D FLCS. In this method, two-dimensional emission-delay correlation maps are constructed from the photon data obtained with the time-correlated single photon counting (TCSPC), and then they are converted to 2D lifetime correlation maps by the inverse Laplace transform. We develop a numerical method to realize reliable transformation, employing the maximum entropy method (MEM). We apply the developed actual 2D FLCS to two real systems, a dye mixture and a DNA hairpin. For the dye mixture, we show that 2D FLCS is experimentally feasible and that it can identify different species in an inhomogeneous sample without any prior knowledge. The application to the DNA hairpin demonstrates that 2D FLCS can disclose microsecond spontaneous dynamics of biological molecules in a visually comprehensible manner, through identifying species as unique lifetime distributions. A FRET pair is attached to the both ends of the DNA hairpin, and the different structures of the DNA hairpin are distinguished as different fluorescence lifetimes in 2D FLCS. By constructing the 2D correlation maps of the fluorescence lifetime of the FRET donor, the equilibrium dynamics between the open and the closed forms of the DNA hairpin is clearly observed as the appearance of the cross peaks between the corresponding fluorescence lifetimes. This equilibrium dynamics of the DNA hairpin is clearly separated from the acceptor-missing DNA that appears as an isolated diagonal peak in the 2D maps. The present study clearly shows that newly developed 2D FLCS can disclose spontaneous structural dynamics of biological molecules with microsecond time resolution.

  2. Nanoantenna array-induced fluorescence enhancement and reduced lifetimes

    DEFF Research Database (Denmark)

    Bakker, R. M.; Drachev, V. P.; Liu, Z.

    2008-01-01

    Enhanced fluorescence is observed from dye molecules interacting with optical nanoantenna arrays. Elliptical gold dimers form individual nanoantennae with tunable plasmon resonances depending upon the geometry of the two particles and the size of the gap between them. A fluorescent dye, Rhodamine...... 800, is uniformly embedded in a dielectric host that coats the nanoantennae. The nanoantennae act to enhance the dye absorption. In turn, emission from the dye drives the plasmon resonance of the antennae; the nanoantennae act to enhance the fluorescence signal and change the angular distribution...... of emission. These effects depend upon the overlap of the plasmon resonance with the excitation wavelength and the fluorescence emission band. A decreased fluorescence lifetime is observed along with highly polarized emission that displays the characteristics of the nanoantenna's dipole mode. Being able...

  3. Plasmonic-based instrument response function for time-resolved fluorescence: toward proper lifetime analysis

    Energy Technology Data Exchange (ETDEWEB)

    Szlazak, Radoslaw; Tutaj, Krzysztof; Grudzinski, Wojciech; Gruszecki, Wieslaw I.; Luchowski, Rafal, E-mail: rafal.luchowski@umcs.pl [Maria Curie-Sklodowska University, Department of Biophysics, Institute of Physics (Poland)

    2013-06-15

    In this report, we investigated the so-called plasmonic platforms prepared to target ultra-short fluorescence and accurate instrumental response function in a time-domain spectroscopy and microscopy. The interaction of metallic nanoparticles with nearby fluorophores results in the increase of the dye fluorescence quantum yield, photostability and decrease of the lifetime parameter. The mentioned properties of platforms were applied to achieve a picosecond fluorescence lifetime (21 ps) of erythrosin B, used later as a better choice for deconvolution of fluorescence decays measured with 'color' sensitive photo-detectors. The ultra-short fluorescence standard based on combination of thin layers of silver film, silver colloidal nanoparticles (about 60 nm in diameter), and top layer of erythrosin B embedded in 0.2 % poly(vinyl) alcohol. The response functions were monitored on two photo-detectors; microchannel plate photomultiplier and single photon avalanche photodiode as a Rayleigh scattering and ultra-short fluorescence. We demonstrated that use of the plasmonic base fluorescence standard as an instrumental response function results in the absence of systematic error in lifetime measurements and analysis.

  4. Fluorescence of ceramic color standards

    International Nuclear Information System (INIS)

    Koo, Annette; Clare, John F.; Nield, Kathryn M.; Deadman, Andrew; Usadi, Eric

    2010-01-01

    Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600 nm and emitted above 700 nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.

  5. Fluorescent standards for photodynamic therapy

    Science.gov (United States)

    Belko, N.; Kavalenka, S.; Samtsov, M.

    2016-08-01

    Photodynamic therapy is an evolving technique for treatment of various oncological diseases. This method employs photosensitizers - species that lead to death of tumor cells after the photoactivation. For further development and novel applications of photodynamic therapy new photosensitizers are required. After synthesis of a new photosensitizer it is important to know its concentration in different biological tissues after its administration and distribution. The concentration is frequently measured by the extraction method, which has some disadvantages, e.g. it requires many biological test subjects that are euthanized during the measurement. We propose to measure the photosensitizer concentration in tissue by its fluorescence. For this purpose fluorescent standards were developed. The standards are robust and simple to produce; their fluorescence signal does not change with time. The fluorescence intensity of fluorescent standards seems to depend linearly on the dye concentration. A set of standards thus allow the calibration of a spectrometer. Finally, the photosensitizer concentration can be determined by the fluorescence intensity after comparing the corresponding spectrum with spectra of the set of fluorescent standards. A biological test subject is not euthanized during this kind of experiment. We hope this more humane technique can be used in future instead of the extraction method.

  6. Refractive index sensing of green fluorescent proteins in living cells using fluorescence lifetime imaging microscopy

    NARCIS (Netherlands)

    van Manen, Henk-Jan; Verkuijlen, Paul; Wittendorp, Paul; Subramaniam, Vinod; van den Berg, Timo K; Roos, Dirk; Otto, Cees

    2008-01-01

    We show that fluorescence lifetime imaging microscopy (FLIM) of green fluorescent protein (GFP) molecules in cells can be used to report on the local refractive index of intracellular GFP. We expressed GFP fusion constructs of Rac2 and gp91(phox), which are both subunits of the phagocyte NADPH

  7. Enhancement of early cervical cancer diagnosis with epithelial layer analysis of fluorescence lifetime images.

    Directory of Open Access Journals (Sweden)

    Jun Gu

    Full Text Available This work reports the use of layer analysis to aid the fluorescence lifetime diagnosis of cervical intraepithelial neoplasia (CIN from H&E stained cervical tissue sections. The mean and standard deviation of lifetimes in single region of interest (ROI of cervical epithelium were previously shown to correlate to the gold standard histopathological classification of early cervical cancer. These previously defined single ROIs were evenly divided into layers for analysis. A 10-layer model revealed a steady increase in fluorescence lifetime from the inner to the outer epithelial layers of healthy tissue sections, suggesting a close association with cellular maturity. The shorter lifetime and minimal lifetime increase towards the epithelial surface of CIN-affected regions are in good agreement with the absence of cellular maturation in CIN. Mean layer lifetimes in the top-half cervical epithelium were used as feature vectors for extreme learning machine (ELM classifier discriminations. It was found that the proposed layer analysis technique greatly improves the sensitivity and specificity to 94.6% and 84.3%, respectively, which can better supplement the traditional gold standard cervical histopathological examinations.

  8. Azadioxatriangulenium: exploring the effect of a 20 ns fluorescence lifetime in fluorescence anisotropy measurements

    Science.gov (United States)

    Bogh, Sidsel A.; Bora, Ilkay; Rosenberg, Martin; Thyrhaug, Erling; Laursen, Bo W.; Just Sørensen, Thomas

    2015-12-01

    Azaoxatriangulenium (ADOTA) has been shown to be highly emissive despite a moderate molar absorption coefficient of the primary electronic transition. As a result, the fluorescence lifetime is ~20 ns, longer than all commonly used red fluorescent organic probes. The electronic transitions in ADOTA are highly polarised (r 0  =  0.38), which in combination with the long fluorescence lifetime extents the size-range of biomolecular weights that can be detected in fluorescence polarisation-based experiments. Here, the rotational dynamics of bovine serum albumin (BSA) are monitored with three different ADOTA derivatives, differing only in constitution of the reactive linker. A detailed study of the degree of labelling, the steady-state anisotropy, and the time-resolved anisotropy of the three different ADOTA-BSA conjugates are reported. The fluorescence quantum yields (ϕ fl) of the free dyes in PBS solution are determined to be ~55%, which is reduced to ~20% in the ADOTA-BSA conjugates. Despite the reduction in ϕ fl, a ~20 ns intensity averaged lifetime is maintained, allowing for the rotational dynamics of BSA to be monitored for up to 100 ns. Thus, ADOTA can be used in fluorescence polarisation assays to fill the gap between commonly used organic dyes and the long luminescence lifetime transition metal complexes. This allows for efficient steady-state fluorescence polarisation assays for detecting binding of analytes with molecular weights of up to 100 kDa.

  9. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging.

    Science.gov (United States)

    Zhao, Qiaole; Schelen, Ben; Schouten, Raymond; van den Oever, Rein; Leenen, René; van Kuijk, Harry; Peters, Inge; Polderdijk, Frank; Bosiers, Jan; Raspe, Marcel; Jalink, Kees; Geert Sander de Jong, Jan; van Geest, Bert; Stoop, Karel; Young, Ian Ted

    2012-12-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device design in a frequency-domain FLIM system. The first stage of evaluation for the camera has been carried out. Camera characteristics such as noise distribution, dark current influence, camera gain, sampling density, sensitivity, linearity of photometric response, and optical transfer function have been studied through experiments. We are able to do lifetime measurement using our modulated, electron-multiplied fluorescence lifetime imaging microscope (MEM-FLIM) camera for various objects, e.g., fluorescein solution, fixed green fluorescent protein (GFP) cells, and GFP-actin stained live cells. A detailed comparison of a conventional microchannel plate (MCP)-based FLIM system and the MEM-FLIM system is presented. The MEM-FLIM camera shows higher resolution and a better image quality. The MEM-FLIM camera provides a new opportunity for performing frequency-domain FLIM.

  10. Measurements of fluorescence lifetime of group III metalo-8-quinolinolates and their use in analytical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, Y; Hiraki, K; Morishige, K; Takahashi, K [Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology; Shigematsu, T

    1976-07-01

    8-Quinolinolates of aluminum, gallium, and indium in chloroform exhibit strong yellowish green fluorescence with an emission maximum at 510, 526, and 528 nm, respectively. The time resolved fluorescence spectra and the fluorescence lifetime properties of these chelates were measured with a time-resolved spectrofluorometer. The fluorescence intensity of these chelates decays exponentially with time t, and obeys the following equation: F=F/sub 0/e-t/tau=F/sub 0/e-k sub(f).t where F/sub 0/ and F are the fluorescence intensity when the exciting light is irradiating and shut off, respectively; tau and k sub(f) being the lifetime and the rate constant for the process of fluorescence emission. The lifetimes of these chelates in chloroform solution at the ordinary temperature were 17.8, 10.1, and 8.4 ns for Al(C/sub 9/H/sub 6/ON)/sub 3/, Ga(C/sub 9/H/sub 6/ON)/sub 3/, and In(C/sub 9/H/sub 6/ON)/sub 3/, respectively. Thus, 8-quinolinolates of group III metals emit the same type radiation with different lifetimes. Between Al-chelate and In-chelate, there were significant difference in the lifetime by 9.4 ns. Then, the logarithmic plot of the composite fluorescence intensity against time is the overlap of some straight lines with different slopes which indicate k sub(f) of various decay processes. The linear portion of the logarithmic plot of the composite fluorescence intensity corresponded to the longer lifetime component (Al-chelate), and by substracting this component from the whole one, the straight line due to the shorter lifetime component (In-chelate) is obtained. Aluminum and indium contents were then determined by comparing the fluorescence intensity of the sample with that of the standard at a definite time (extrapolated to t=0). By using this composite decay curve, the composition of mixtures of nx10/sup -4/ mol/l of Al and In-chelates in chloroform could be determined.

  11. Bessel beam fluorescence lifetime tomography of live embryos (Conference Presentation)

    Science.gov (United States)

    Xu, Dongli; Peng, Leilei

    2016-03-01

    Optical tomography allows isotropic 3D imaging of embryos. Scanning-laser optical tomography (SLOT) has superior light collecting efficiency than wide-field optical tomography, making it ideal for fluorescence imaging of live embryos. We previously reported an imaging system that combines SLOT with a novel Fourier-multiplexed fluorescence lifetime imaging (FmFLIM) technique named FmFLIM-SLOT. FmFLIM-SLOT performs multiplexed FLIM-FRET readout of multiple FRET sensors in live embryos. Here we report a recent effort on improving the spatial resolution of the FmFLIM-SLOT system in order to image complex biochemical processes in live embryos at the cellular level. Optical tomography has to compromise between resolution and the depth of view. In SLOT, the commonly-used focused Gaussian beam diverges quickly from the focal plane, making it impossible to achieve high resolution imaging in a large volume specimen. We thus introduce Bessel beam laser-scanning tomography, which illuminates the sample with a spatial-light-modulator-generated Bessel beam that has an extended focal depth. The Bessel beam is scanned across the whole specimen. Fluorescence projection images are acquired at equal angular intervals as the sample rotates. Reconstruction artifacts due to annular-rings of the Bessel beam are removed by a modified 3D filtered back projection algorithm. Furthermore, in combination of Fourier-multiplexing fluorescence lifetime imaging (FmFLIM) method, the Bessel FmFLIM-SLOT system is capable of perform 3D lifetime imaging of live embryos at cellular resolution. The system is applied to in-vivo imaging of transgenic Zebrafish embryos. Results prove that Bessel FmFLIM-SLOT is a promising imaging method in development biology research.

  12. Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging.

    Science.gov (United States)

    Zhao, Ming; Li, Yu; Peng, Leilei

    2014-05-05

    We present a novel excitation-emission multiplexed fluorescence lifetime microscopy (FLIM) method that surpasses current FLIM techniques in multiplexing capability. The method employs Fourier multiplexing to simultaneously acquire confocal fluorescence lifetime images of multiple excitation wavelength and emission color combinations at 44,000 pixels/sec. The system is built with low-cost CW laser sources and standard PMTs with versatile spectral configuration, which can be implemented as an add-on to commercial confocal microscopes. The Fourier lifetime confocal method allows fast multiplexed FLIM imaging, which makes it possible to monitor multiple biological processes in live cells. The low cost and compatibility with commercial systems could also make multiplexed FLIM more accessible to biological research community.

  13. Fluorescence lifetime, dipole orientation and bilayer polymer films

    Science.gov (United States)

    Ho, Xuan Long; Chen, Po-Jui; Woon, Wei-Yen; White, Jonathon David

    2017-10-01

    Bilayer films consisting of the optically transparent polymers, polystyrene (PS) and poly(methyl methacrylate) (PMMA) were spin-cast on glass substrates. The upper 13.5 nm layer (PS) was lightly doped with Rhodamine-6 G (RH6G) or MEH-PPV. While the fluorescence of MEH-PPV was independent of PMMA thickness, the lifetime of RH6G increased 3-fold as the underlying PMMA thickness increased from 0 to 500 nm while the collected flux decreased suggesting a reorientation of the smaller molecule's dipole with respect to the air-polymer interface with PMMA thickness. This suggests lifetime may find application for nondestructive thickness measurements of transparent films with sub-micron lateral resolution and large range.

  14. Fluorescence Lifetime Imaging in Stargardt Disease: Potential Marker for Disease Progression

    OpenAIRE

    Dysli Chantal; Wolf Sebastian; Hatz Katja; Zinkernagel Martin

    2016-01-01

    PURPOSE The purpose of this study was to describe autofluorescence lifetime characteristics in Stargardt disease (STGD) using fluorescence lifetime imaging ophthalmoscopy (FLIO) and to investigate potential prognostic markers for disease activity and progression. METHODS Fluorescence lifetime data of 16 patients with STGD (mean age, 40 years; range, 22-56 years) and 15 age-matched controls were acquired using a fluorescence lifetime imaging ophthalmoscope based on a Heidelberg Eng...

  15. Refractive Index Sensing of Green Fluorescent Proteins in Living Cells Using Fluorescence Lifetime Imaging Microscopy

    Science.gov (United States)

    van Manen, Henk-Jan; Verkuijlen, Paul; Wittendorp, Paul; Subramaniam, Vinod; van den Berg, Timo K.; Roos, Dirk; Otto, Cees

    2008-01-01

    We show that fluorescence lifetime imaging microscopy (FLIM) of green fluorescent protein (GFP) molecules in cells can be used to report on the local refractive index of intracellular GFP. We expressed GFP fusion constructs of Rac2 and gp91phox, which are both subunits of the phagocyte NADPH oxidase enzyme, in human myeloid PLB-985 cells and showed by high-resolution confocal fluorescence microscopy that GFP-Rac2 and GFP-gp91phox are targeted to the cytosol and to membranes, respectively. Frequency-domain FLIM experiments on these PLB-985 cells resulted in average fluorescence lifetimes of 2.70 ns for cytosolic GFP-Rac2 and 2.31 ns for membrane-bound GFP-gp91phox. By comparing these lifetimes with a calibration curve obtained by measuring GFP lifetimes in PBS/glycerol mixtures of known refractive index, we found that the local refractive indices of cytosolic GFP-Rac2 and membrane-targeted GFP-gp91phox are ∼1.38 and ∼1.46, respectively, which is in good correspondence with reported values for the cytosol and plasma membrane measured by other techniques. The ability to measure the local refractive index of proteins in living cells by FLIM may be important in revealing intracellular spatial heterogeneities within organelles such as the plasma and phagosomal membrane. PMID:18223002

  16. The enhanced cyan fluorescent protein: a sensitive pH sensor for fluorescence lifetime imaging.

    Science.gov (United States)

    Poëa-Guyon, Sandrine; Pasquier, Hélène; Mérola, Fabienne; Morel, Nicolas; Erard, Marie

    2013-05-01

    pH is an important parameter that affects many functions of live cells, from protein structure or function to several crucial steps of their metabolism. Genetically encoded pH sensors based on pH-sensitive fluorescent proteins have been developed and used to monitor the pH of intracellular compartments. The quantitative analysis of pH variations can be performed either by ratiometric or fluorescence lifetime detection. However, most available genetically encoded pH sensors are based on green and yellow fluorescent proteins and are not compatible with multicolor approaches. Taking advantage of the strong pH sensitivity of enhanced cyan fluorescent protein (ECFP), we demonstrate here its suitability as a sensitive pH sensor using fluorescence lifetime imaging. The intracellular ECFP lifetime undergoes large changes (32 %) in the pH 5 to pH 7 range, which allows accurate pH measurements to better than 0.2 pH units. By fusion of ECFP with the granular chromogranin A, we successfully measured the pH in secretory granules of PC12 cells, and we performed a kinetic analysis of intragranular pH variations in living cells exposed to ammonium chloride.

  17. Thermally activated delayed fluorescence organic dots for two-photon fluorescence lifetime imaging

    Science.gov (United States)

    He, Tingchao; Ren, Can; Li, Zhuohua; Xiao, Shuyu; Li, Junzi; Lin, Xiaodong; Ye, Chuanxiang; Zhang, Junmin; Guo, Lihong; Hu, Wenbo; Chen, Rui

    2018-05-01

    Autofluorescence is a major challenge in complex tissue imaging when molecules present in the biological tissue compete with the fluorophore. This issue may be resolved by designing organic molecules with long fluorescence lifetimes. The present work reports the two-photon absorption (TPA) properties of a thermally activated delayed fluorescence (TADF) molecule with carbazole as the electron donor and dicyanobenzene as the electron acceptor (i.e., 4CzIPN). The results indicate that 4CzIPN exhibits a moderate TPA cross-section (˜9 × 10-50 cm4 s photon-1), high fluorescence quantum yield, and a long fluorescence lifetime (˜1.47 μs). 4CzIPN was compactly encapsulated into an amphiphilic copolymer via nanoprecipitation to achieve water-soluble organic dots. Interestingly, 4CzIPN organic dots have been utilized in applications involving two-photon fluorescence lifetime imaging (FLIM). Our work aptly demonstrates that TADF molecules are promising candidates of nonlinear optical probes for developing next-generation multiphoton FLIM applications.

  18. Using multiphoton fluorescence lifetime imaging to characterize liver damage and fluorescein disposition in liver in vivo

    Science.gov (United States)

    Thorling, Camilla A.; Studier, Hauke; Crawford, Darrell; Roberts, Michael S.

    2016-03-01

    Liver disease is the fifth most common cause of death and unlike many other major causes of mortality, liver disease rates are increasing rather than decreasing. There is no ideal measurement of liver disease and although biopsies are the gold standard, this only allows for a spot examination and cannot follow dynamic processes of the liver. Intravital imaging has the potential to extract detailed information over a larger sampling area continuously. The aim of this project was to investigate whether multiphoton and fluorescence lifetime imaging microscopy could detect early liver damage and to assess whether it could detect changes in metabolism of fluorescein in normal and diseased livers. Four experimental groups were used in this study: 1) control; 2) ischemia reperfusion injury; 3) steatosis and 4) steatosis with ischemia reperfusion injury. Results showed that multiphoton microscopy could visualize morphological changes such as decreased fluorescence of endogenous fluorophores and the presence of lipid droplets, characteristic of steatosis. Fluorescence lifetime imaging microscopy showed increase in NADPH in steatosis with and without ischemia reperfusion injury and could detect changes in metabolism of fluorescein to fluorescein monoglurcuronide, which was impaired in steatosis with ischemia reperfusion injury. These results concluded that the combination of multiphoton microscopy and fluorescence lifetime imaging is a promising method of assessing early stage liver damage and that it can be used to study changes in drug metabolism in the liver as an indication of liver disease and has the potential to replace the traditional static liver biopsy currently used.

  19. Community detection for fluorescent lifetime microscopy image segmentation

    Science.gov (United States)

    Hu, Dandan; Sarder, Pinaki; Ronhovde, Peter; Achilefu, Samuel; Nussinov, Zohar

    2014-03-01

    Multiresolution community detection (CD) method has been suggested in a recent work as an efficient method for performing unsupervised segmentation of fluorescence lifetime (FLT) images of live cell images containing fluorescent molecular probes.1 In the current paper, we further explore this method in FLT images of ex vivo tissue slices. The image processing problem is framed as identifying clusters with respective average FLTs against a background or "solvent" in FLT imaging microscopy (FLIM) images derived using NIR fluorescent dyes. We have identified significant multiresolution structures using replica correlations in these images, where such correlations are manifested by information theoretic overlaps of the independent solutions ("replicas") attained using the multiresolution CD method from different starting points. In this paper, our method is found to be more efficient than a current state-of-the-art image segmentation method based on mixture of Gaussian distributions. It offers more than 1:25 times diversity based on Shannon index than the latter method, in selecting clusters with distinct average FLTs in NIR FLIM images.

  20. A Compact Fluorescence Lifetime Excitation-Emission Spectrometer (FLEXEMS) for Detecting Trace Organics, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovative Research (SBIR) effort, Leiden Measurement Technology (LMT) proposes to design and build the Fluorescence Lifetime Excitation...

  1. A Compact Fluorescence Lifetime Excitation-Emission Spectrometer (FLEXEMS) for Detecting Trace Organics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovative Research (SBIR) effort, Leiden Measurement Technology (LMT) proposes to design and build the Fluorescence Lifetime Excitation...

  2. Generation of a new spectral format, the lifetime synchronous spectrum (LiSS), using phase-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Shaver, J.M.; McGown, L.B.

    1994-01-01

    A new fluorescence spectral format is introduced in which fluorescence lifetime is shown as a function of synchronously scanned wavelength to generate a Lifetime Synchronous Spectrum (LiSS). Lifetimes are determined in the frequency domain with the use of Phase-Resolved Fluorescence Spectroscopy (PRFS) to obtain the phase of the fluorescence signal. Theory and construction of the LiSS are presented and experimental results are shown for solutions of single components and simple binary and ternary mixtures. These results show how the lifetime information in the LiSS augments the steady-state intensity information of a standard synchronous spectrum, providing unique information for identification of components and resolution of overlapping spectral peaks. The LiSS technique takes advantage of noise reduction inherent in the extraction of lifetime from PRFS in addition to standard spectral smoothing techniques. The precision of phase determination through PRFS is found to be comparable to that of direct phase measurements at normal fluorescence intensities and superior for low-intensity signals

  3. An electronically tunable ultrafast laser source applied to fluorescence imaging and fluorescence lifetime imaging microscopy

    International Nuclear Information System (INIS)

    Dunsby, C; Lanigan, P M P; McGinty, J; Elson, D S; Requejo-Isidro, J; Munro, I; Galletly, N; McCann, F; Treanor, B; Oenfelt, B; Davis, D M; Neil, M A A; French, P M W

    2004-01-01

    Fluorescence imaging is used widely in microscopy and macroscopic imaging applications for fields ranging from biomedicine to materials science. A critical component for any fluorescence imaging system is the excitation source. Traditionally, wide-field systems use filtered thermal or arc-generated white light sources, while point scanning confocal microscope systems require spatially coherent (point-like) laser sources. Unfortunately, the limited range of visible wavelengths available from conventional laser sources constrains the design and usefulness of fluorescent probes in confocal microscopy. A 'hands-off' laser-like source, electronically tunable across the visible spectrum, would be invaluable for fluorescence imaging and provide new opportunities, e.g. automated excitation fingerprinting and in situ measurement of excitation cross-sections. Yet more information can be obtained using fluorescence lifetime imaging (FLIM), which requires that the light source be pulsed or rapidly modulated. We show how a white light continuum, generated by injecting femtosecond optical radiation into a micro-structured optical fibre, coupled with a simple prism-based tunable filter arrangement, can fulfil all these roles as a continuously electronically tunable (435-1150 nm) visible ultrafast light source in confocal, wide-field and FLIM systems

  4. Time-resolved laser fluorescence spectroscopy of organic ligands by europium: Fluorescence quenching and lifetime properties

    Science.gov (United States)

    Nouhi, A.; Hajjoul, H.; Redon, R.; Gagné, J. P.; Mounier, S.

    2018-03-01

    Time-resolved Laser Fluorescence Spectroscopy (TRLFS) has proved its usefulness in the fields of biophysics, life science and geochemistry to characterize the fluorescence probe molecule with its chemical environment. The purpose of this study is to demonstrate the applicability of this powerful technique combined with Steady-State (S-S) measurements. A multi-mode factor analysis, in particular CP/PARAFAC, was used to analyze the interaction between Europium (Eu) and Humic substances (HSs) extracted from Saint Lawrence Estuary in Canada. The Saint Lawrence system is a semi-enclosed water stream with connections to the Atlantic Ocean and is an excellent natural laboratory. CP/PARAFAC applied to fluorescence S-S data allows introspecting ligands-metal interactions and the one-site 1:1 modeling gives information about the stability constants. From the spectral signatures and decay lifetimes data given by TRLFS, one can deduce the fluorescence quenching which modifies the fluorescence and discuss its mechanisms. Results indicated a relatively strong binding ability between europium and humic substances samples (Log K value varies from 3.38 to 5.08 at pH 7.00). Using the Stern-Volmer plot, it has been concluded that static and dynamic quenching takes places in the case of salicylic acid and europium interaction while for HSs interaction only a static quenching is observed.

  5. Ns-scaled time-gated fluorescence lifetime imaging for forensic document examination

    Science.gov (United States)

    Zhong, Xin; Wang, Xinwei; Zhou, Yan

    2018-01-01

    A method of ns-scaled time-gated fluorescence lifetime imaging (TFLI) is proposed to distinguish different fluorescent substances in forensic document examination. Compared with Video Spectral Comparator (VSC) which can examine fluorescence intensity images only, TFLI can detect questioned documents like falsification or alteration. TFLI system can enhance weak signal by accumulation method. The two fluorescence intensity images of the interval delay time tg are acquired by ICCD and fitted into fluorescence lifetime image. The lifetimes of fluorescence substances are represented by different colors, which make it easy to detect the fluorescent substances and the sequence of handwritings. It proves that TFLI is a powerful tool for forensic document examination. Furthermore, the advantages of TFLI system are ns-scaled precision preservation and powerful capture capability.

  6. The LB Films of Dansyl Chloride Labeled Octadecylamine and Its Fluorescence Lifetime

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) in order to simplify and understand the LB films of fluorescent probe labeling proteins.Its monolayer and multilayers in the absence and presence of stearic acid were deposited by LB technique.Fluorescence spectra and lifetimes of the fluorescent products were studied to elucidate the microenvironment of molecules in the LB films.

  7. Non-invasive imaging of skin cancer with fluorescence lifetime imaging using two photon tomography

    Science.gov (United States)

    Patalay, Rakesh; Talbot, Clifford; Alexandrov, Yuriy; Munro, Ian; Breunig, Hans Georg; König, Karsten; Warren, Sean; Neil, Mark A. A.; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Christopher

    2011-07-01

    Multispectral fluorescence lifetime imaging (FLIM) using two photon microscopy as a non-invasive technique for the diagnosis of skin lesions is described. Skin contains fluorophores including elastin, keratin, collagen, FAD and NADH. This endogenous contrast allows tissue to be imaged without the addition of exogenous agents and allows the in vivo state of cells and tissues to be studied. A modified DermaInspect® multiphoton tomography system was used to excite autofluorescence at 760 nm in vivo and on freshly excised ex vivo tissue. This instrument simultaneously acquires fluorescence lifetime images in four spectral channels between 360-655 nm using time-correlated single photon counting and can also provide hyperspectral images. The multispectral fluorescence lifetime images were spatially segmented and binned to determine lifetimes for each cell by fitting to a double exponential lifetime model. A comparative analysis between the cellular lifetimes from different diagnoses demonstrates significant diagnostic potential.

  8. Quantitative fluorescence lifetime spectroscopy in turbid media: comparison of theoretical, experimental and computational methods

    International Nuclear Information System (INIS)

    Vishwanath, Karthik; Mycek, Mary-Ann; Pogue, Brian

    2002-01-01

    A Monte Carlo model developed to simulate time-resolved fluorescence propagation in a semi-infinite turbid medium was validated against previously reported theoretical and computational results. Model simulations were compared to experimental measurements of fluorescence spectra and lifetimes on tissue-simulating phantoms for single and dual fibre-optic probe geometries. Experiments and simulations using a single probe revealed that scattering-induced artefacts appeared in fluorescence emission spectra, while fluorescence lifetimes were unchanged. Although fluorescence lifetime measurements are generally more robust to scattering artefacts than are measurements of fluorescence spectra, in the dual-probe geometry scattering-induced changes in apparent lifetime were predicted both from diffusion theory and via Monte Carlo simulation, as well as measured experimentally. In all cases, the recovered apparent lifetime increased with increasing scattering and increasing source-detector separation. Diffusion theory consistently underestimated the magnitude of these increases in apparent lifetime (predicting a maximum increase of ∼15%), while Monte Carlo simulations and experiment were closely matched (showing increases as large as 30%). These results indicate that quantitative simulations of time-resolved fluorescence propagation in turbid media will be important for accurate recovery of fluorophore lifetimes in biological spectroscopy and imaging applications. (author)

  9. Recommendations for fluorescence instrument qualification: the new ASTM Standard Guide.

    Science.gov (United States)

    DeRose, Paul C; Resch-Genger, Ute

    2010-03-01

    Aimed at improving quality assurance and quantitation for modern fluorescence techniques, ASTM International (ASTM) is about to release a Standard Guide for Fluorescence, reviewed here. The guide's main focus is on steady state fluorometry, for which available standards and instrument characterization procedures are discussed along with their purpose, suitability, and general instructions for use. These include the most relevant instrument properties needing qualification, such as linearity and spectral responsivity of the detection system, spectral irradiance reaching the sample, wavelength accuracy, sensitivity or limit of detection for an analyte, and day-to-day performance verification. With proper consideration of method-inherent requirements and limitations, many of these procedures and standards can be adapted to other fluorescence techniques. In addition, procedures for the determination of other relevant fluorometric quantities including fluorescence quantum yields and fluorescence lifetimes are briefly introduced. The guide is a clear and concise reference geared for users of fluorescence instrumentation at all levels of experience and is intended to aid in the ongoing standardization of fluorescence measurements.

  10. Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection.

    Science.gov (United States)

    Lei, Rong; Jiang, Hongshan; Hu, Fan; Yan, Jin; Zhu, Shuifang

    2017-02-01

    Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.

  11. A Fast Global Fitting Algorithm for Fluorescence Lifetime Imaging Microscopy Based on Image Segmentation

    OpenAIRE

    Pelet, S.; Previte, M.J.R.; Laiho, L.H.; So, P.T. C.

    2004-01-01

    Global fitting algorithms have been shown to improve effectively the accuracy and precision of the analysis of fluorescence lifetime imaging microscopy data. Global analysis performs better than unconstrained data fitting when prior information exists, such as the spatial invariance of the lifetimes of individual fluorescent species. The highly coupled nature of global analysis often results in a significantly slower convergence of the data fitting algorithm as compared with unconstrained ana...

  12. In vivo multiphoton tomography and fluorescence lifetime imaging of human brain tumor tissue.

    Science.gov (United States)

    Kantelhardt, Sven R; Kalasauskas, Darius; König, Karsten; Kim, Ella; Weinigel, Martin; Uchugonova, Aisada; Giese, Alf

    2016-05-01

    High resolution multiphoton tomography and fluorescence lifetime imaging differentiates glioma from adjacent brain in native tissue samples ex vivo. Presently, multiphoton tomography is applied in clinical dermatology and experimentally. We here present the first application of multiphoton and fluorescence lifetime imaging for in vivo imaging on humans during a neurosurgical procedure. We used a MPTflex™ Multiphoton Laser Tomograph (JenLab, Germany). We examined cultured glioma cells in an orthotopic mouse tumor model and native human tissue samples. Finally the multiphoton tomograph was applied to provide optical biopsies during resection of a clinical case of glioblastoma. All tissues imaged by multiphoton tomography were sampled and processed for conventional histopathology. The multiphoton tomograph allowed fluorescence intensity- and fluorescence lifetime imaging with submicron spatial resolution and 200 picosecond temporal resolution. Morphological fluorescence intensity imaging and fluorescence lifetime imaging of tumor-bearing mouse brains and native human tissue samples clearly differentiated tumor and adjacent brain tissue. Intraoperative imaging was found to be technically feasible. Intraoperative image quality was comparable to ex vivo examinations. To our knowledge we here present the first intraoperative application of high resolution multiphoton tomography and fluorescence lifetime imaging of human brain tumors in situ. It allowed in vivo identification and determination of cell density of tumor tissue on a cellular and subcellular level within seconds. The technology shows the potential of rapid intraoperative identification of native glioma tissue without need for tissue processing or staining.

  13. Time gated fluorescence lifetime imaging and micro-volume spectroscopy using two-photon excitation

    NARCIS (Netherlands)

    Sytsma, J.; Vroom, J.M.; de Grauw, C.J.; Gerritsen, H.C.

    A scanning microscope utilizing two-photon excitation in combination with fluorescence lifetime contrast is presented. The microscope makes use of a tunable femtosecond titanium:sapphire laser enabling the two-photon excitation of a broad range of fluorescent molecules, including UV probes.

  14. Fluorophore:dendrimer ratio impacts cellular uptake and intracellular fluorescence lifetime.

    Science.gov (United States)

    Dougherty, Casey A; Vaidyanathan, Sriram; Orr, Bradford G; Banaszak Holl, Mark M

    2015-02-18

    G5-NH2-TAMRAn (n = 1-4, 5+, and 1.5(avg)) were prepared with n = 1-4 as a precise dye:dendrimer ratio, 5+ as a mixture of dendrimers with 5 or more dye per dendrimer, and 1.5(avg) as a Poisson distribution of dye:dendrimer ratios with a mean of 1.5 dye per dendrimer. The absorption intensity increased sublinearly with n whereas the fluorescence emission and lifetime decreased with an increasing number of dyes per dendrimer. Flow cytometry was employed to quantify uptake into HEK293A cells. Dendrimers with 2-4 dyes were found to have greater uptake than dendrimer with a single dye. Fluorescence lifetime imaging microscopy (FLIM) showed that the different dye:dendrimer ratio alone was sufficient to change the fluorescence lifetime of the material observed inside cells. We also observed that the lifetime of G5-NH2-TAMRA5+ increased when present in the cell as compared to solution. However, cells treated with G5-NH2-TAMRA1.5(avg) did not exhibit the high lifetime components present in G5-NH2-TAMRA1 and G5-NH2-TAMRA5+. In general, the effects of the dye:dendrimer ratio on fluorescence lifetime were of similar magnitude to environmentally induced lifetime shifts.

  15. Fluorescence Lifetime Correlation Spectroscopy (FLCS): Concepts, Applications and Outlook

    Czech Academy of Sciences Publication Activity Database

    Kapusta, Peter; Macháň, Radek; Benda, A.; Hof, Martin

    2012-01-01

    Roč. 13, č. 10 (2012), s. 12890-12910 E-ISSN 1422-0067 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : fluorescence correlation spectroscopy (FCS) * time correlated single photon counting (TCSPC) * fluorescence cross-correlation spectroscopy (FCCS) Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.464, year: 2012

  16. Miniaturized side-viewing imaging probe for fluorescence lifetime imaging (FLIM): validation with fluorescence dyes, tissue structural proteins and tissue specimens

    OpenAIRE

    Elson, DS; Jo, JA; Marcu, L

    2007-01-01

    We report a side viewing fibre-based endoscope that is compatible with intravascular imaging and fluorescence lifetime imaging microscopy (FLIM). The instrument has been validated through testing with fluorescent dyes and collagen and elastin powders using the Laguerre expansion deconvolution technique to calculate the fluorescence lifetimes. The instrument has also been tested on freshly excised unstained animal vascular tissues.

  17. Distribution of diffusion times determined by fluorescence (lifetime) correlation spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Pánek, Jiří; Loukotová, Lenka; Hrubý, Martin; Štěpánek, Petr

    2018-01-01

    Roč. 51, č. 8 (2018), s. 2796-2804 ISSN 0024-9297 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : polymer solution * fluorescence correlation spectroscopy * diffusion time distribution Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 5.835, year: 2016

  18. In vivo fluorescence lifetime imaging for monitoring the efficacy of the cancer treatment.

    Science.gov (United States)

    Ardeshirpour, Yasaman; Chernomordik, Victor; Hassan, Moinuddin; Zielinski, Rafal; Capala, Jacek; Gandjbakhche, Amir

    2014-07-01

    Advances in tumor biology created a foundation for targeted therapy aimed at inactivation of specific molecular mechanisms responsible for cell malignancy. In this paper, we used in vivo fluorescence lifetime imaging with HER2-targeted fluorescent probes as an alternative imaging method to investigate the efficacy of targeted therapy with 17-DMAG (an HSP90 inhibitor) on tumors with high expression of HER2 receptors. HER2-specific Affibody, conjugated to Alexafluor 750, was injected into nude mice bearing HER2-positive tumor xenograft. The fluorescence lifetime was measured before treatment and monitored after the probe injections at 12 hours after the last treatment dose, when the response to the 17-DMAG therapy was the most pronounced as well as a week after the last treatment when the tumors grew back almost to their pretreatment size. Imaging results showed significant difference between the fluorescence lifetimes at the tumor and the contralateral site (∼0.13 ns) in the control group (before treatment) and 7 days after the last treatment when the tumors grew back to their pretreatment dimensions. However, at the time frame that the treatment had its maximum effect (12 hours after the last treatment), the difference between the fluorescence lifetime at the tumor and contralateral site decreased to 0.03 ns. The results showed a good correlation between fluorescence lifetime and the efficacy of the treatment. These findings show that in vivo fluorescence lifetime imaging can be used as a promising molecular imaging tool for monitoring the treatment outcome in preclinical models and potentially in patients. ©2014 American Association for Cancer Research.

  19. In-vivo fluorescence lifetime imaging for monitoring the efficacy of the cancer treatment

    Science.gov (United States)

    Ardeshirpour, Yasaman; Chernomordik, Victor; Hassan, Moinuddin; Zielinski, Rafal; Capala, Jacek; Gandjbakhche, Amir

    2015-01-01

    Purpose Advances in tumor biology created a foundation for targeted therapy aimed at inactivation of specific molecular mechanisms responsible for cell malignancy. In this paper, we used in-vivo fluorescence lifetime imaging with HER2 targeted fluorescent probes as an alternative imaging method to investigate the efficacy of targeted therapy with 17-DMAG (an HSP90 inhibitor) on tumors with high expression of HER2 receptors. Experimental Design HER2-specific Affibody, conjugated to Alexafluor 750, was injected into nude mice, bearing HER2-positive tumor xenograft. The fluorescence lifetime was measured before treatment and monitored after the probe injections at 12 hours after the last treatment dose, when the response to the 17-DMAG therapy was the most pronounced as well as a week after the last treatment when the tumors grew back almost to their pre-treatment size. Results Imaging results showed significant difference between the fluorescence lifetimes at the tumor and the contralateral site (~0.13ns) in the control group (before treatment) and 7 days after the last treatment when the tumors grew back to their pretreatment dimensions. However, at the time frame that the treatment had its maximum effect (12 hours after the last treatment) the difference between the fluorescence lifetime at the tumor and contralateral site decreased to 0.03ns. Conclusions The results showed a good correlation between fluorescence lifetime and the efficacy of the treatment. These findings show that in-vivo fluorescence lifetime imaging can be used as a promising molecular imaging tool for monitoring the treatment outcome in preclinical models and potentially in patients. PMID:24671949

  20. Portable fluorescence lifetime spectroscopy system for in-situ interrogation of biological tissues

    Science.gov (United States)

    Saito Nogueira, Marcelo; Cosci, Alessandro; Teixeira Rosa, Ramon Gabriel; Salvio, Ana Gabriela; Pratavieira, Sebastião; Kurachi, Cristina

    2017-12-01

    Fluorescence spectroscopy and lifetime techniques are potential methods for optical diagnosis and characterization of biological tissues with an in-situ, fast, and noninvasive interrogation. Several diseases may be diagnosed due to differences in the fluorescence spectra of targeted fluorophores, when, these spectra are similar, considering steady-state fluorescence, others may be detected by monitoring their fluorescence lifetime. Despite this complementarity, most of the current fluorescence lifetime systems are not robust and portable, and not being feasible for clinical applications. We describe the assembly of a fluorescence lifetime spectroscopy system in a suitcase, its characterization, and validation with clinical measurements of skin lesions. The assembled system is all encased and robust, maintaining its mechanical, electrical, and optical stability during transportation, and is feasible for clinical measurements. The instrument response function measured was about 300 ps, and the system is properly calibrated. At the clinical study, the system showed to be reliable, and the achieved spectroscopy results support its potential use as an auxiliary tool for skin diagnostics.

  1. Portable fluorescence lifetime spectroscopy system for in-situ interrogation of biological tissues.

    Science.gov (United States)

    Saito Nogueira, Marcelo; Cosci, Alessandro; Teixeira Rosa, Ramon Gabriel; Salvio, Ana Gabriela; Pratavieira, Sebastião; Kurachi, Cristina

    2017-10-01

    Fluorescence spectroscopy and lifetime techniques are potential methods for optical diagnosis and characterization of biological tissues with an in-situ, fast, and noninvasive interrogation. Several diseases may be diagnosed due to differences in the fluorescence spectra of targeted fluorophores, when, these spectra are similar, considering steady-state fluorescence, others may be detected by monitoring their fluorescence lifetime. Despite this complementarity, most of the current fluorescence lifetime systems are not robust and portable, and not being feasible for clinical applications. We describe the assembly of a fluorescence lifetime spectroscopy system in a suitcase, its characterization, and validation with clinical measurements of skin lesions. The assembled system is all encased and robust, maintaining its mechanical, electrical, and optical stability during transportation, and is feasible for clinical measurements. The instrument response function measured was about 300 ps, and the system is properly calibrated. At the clinical study, the system showed to be reliable, and the achieved spectroscopy results support its potential use as an auxiliary tool for skin diagnostics. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  2. Use of multiphoton tomography and fluorescence lifetime imaging to investigate skin pigmentation in vivo

    Science.gov (United States)

    Dancik, Yuri; Favre, Amandine; Loy, Chong Jin; Zvyagin, Andrei V.; Roberts, Michael S.

    2013-02-01

    There is a growing body of literature showing the usefulness of multiphoton tomography (MPT) and fluorescence lifetime imaging for in situ characterization of skin constituents and the ensuing development of noninvasive diagnostic tools against skin diseases. Melanin and pigmentation-associated skin cancers constitute some of the major applications. We show that MPT and fluorescence lifetime imaging can be used to measure changes in cutaneous melanin concentration and that these can be related to the visible skin color. Melanin in the skin of African, Indian, Caucasian, and Asian volunteers is detected on the basis of its emission wavelength and fluorescence lifetimes in solution and in a melanocyte-keratinocyte cell culture. Fluorescence intensity is used to characterize the melanin content and distribution as a function of skin type and depth into the skin (stratum granulosum and stratum basale). The measured fluorescence intensities in given skin types agree with melanin amounts reported by others using biopsies. Our results suggest that spatial distribution of melanin in skin can be studied using MPT and fluorescence lifetime imaging, but further studies are needed to ascertain that the method can resolve melanin amount in smaller depth intervals.

  3. Fluorescence lifetime correlation spectroscopy combined with lifetime tuning: New perspectives in supported phospholipid bilayer research

    Czech Academy of Sciences Publication Activity Database

    Benda, Aleš; Fagulová, Veronika; Deyneka, Alexander; Enderlain, J.; Hof, Martin

    2006-01-01

    Roč. 22, č. 23 (2006), s. 9580-9585 ISSN 0743-7463 R&D Projects: GA ČR GA203/05/2308; GA MŠk LC06063 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100522 Keywords : spectroscopy * fluorescence * FLCS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.902, year: 2006

  4. Time-Resolved Fluorescence Spectroscopy and Fluorescence Lifetime Imaging Microscopy for Characterization of Dendritic Polymer Nanoparticles and Applications in Nanomedicine

    Directory of Open Access Journals (Sweden)

    Alexander Boreham

    2016-12-01

    Full Text Available The emerging field of nanomedicine provides new approaches for the diagnosis and treatment of diseases, for symptom relief and for monitoring of disease progression. One route of realizing this approach is through carefully constructed nanoparticles. Due to the small size inherent to the nanoparticles a proper characterization is not trivial. This review highlights the application of time-resolved fluorescence spectroscopy and fluorescence lifetime imaging microscopy (FLIM for the analysis of nanoparticles, covering aspects ranging from molecular properties to particle detection in tissue samples. The latter technique is particularly important as FLIM allows for distinguishing of target molecules from the autofluorescent background and, due to the environmental sensitivity of the fluorescence lifetime, also offers insights into the local environment of the nanoparticle or its interactions with other biomolecules. Thus, these techniques offer highly suitable tools in the fields of particle development, such as organic chemistry, and in the fields of particle application, such as in experimental dermatology or pharmaceutical research.

  5. Time-Resolved Fluorescence Spectroscopy and Fluorescence Lifetime Imaging Microscopy for Characterization of Dendritic Polymer Nanoparticles and Applications in Nanomedicine.

    Science.gov (United States)

    Boreham, Alexander; Brodwolf, Robert; Walker, Karolina; Haag, Rainer; Alexiev, Ulrike

    2016-12-24

    The emerging field of nanomedicine provides new approaches for the diagnosis and treatment of diseases, for symptom relief and for monitoring of disease progression. One route of realizing this approach is through carefully constructed nanoparticles. Due to the small size inherent to the nanoparticles a proper characterization is not trivial. This review highlights the application of time-resolved fluorescence spectroscopy and fluorescence lifetime imaging microscopy (FLIM) for the analysis of nanoparticles, covering aspects ranging from molecular properties to particle detection in tissue samples. The latter technique is particularly important as FLIM allows for distinguishing of target molecules from the autofluorescent background and, due to the environmental sensitivity of the fluorescence lifetime, also offers insights into the local environment of the nanoparticle or its interactions with other biomolecules. Thus, these techniques offer highly suitable tools in the fields of particle development, such as organic chemistry, and in the fields of particle application, such as in experimental dermatology or pharmaceutical research.

  6. Multiphoton Laser Microscopy and Fluorescence Lifetime Imaging for the Evaluation of the Skin

    Directory of Open Access Journals (Sweden)

    Stefania Seidenari

    2012-01-01

    Full Text Available Multiphoton laser microscopy is a new, non-invasive technique providing access to the skin at a cellular and subcellular level, which is based both on autofluorescence and fluorescence lifetime imaging. Whereas the former considers fluorescence intensity emitted by epidermal and dermal fluorophores and by the extra-cellular matrix, fluorescence lifetime imaging (FLIM, is generated by the fluorescence decay rate. This innovative technique can be applied to the study of living skin, cell cultures and ex vivo samples. Although still limited to the clinical research field, the development of multiphoton laser microscopy is thought to become suitable for a practical application in the next few years: in this paper, we performed an accurate review of the studies published so far, considering the possible fields of application of this imaging method and providing high quality images acquired in the Department of Dermatology of the University of Modena.

  7. Fluorescence lifetime measurements of native and glycated human serum albumin and bovine serum albumin

    Science.gov (United States)

    Joshi, Narahari V.; Joshi, Virgina O. d.; Contreras, Silvia; Gil, Herminia; Medina, Honorio; Siemiarczuk, Aleksander

    1999-05-01

    Nonenzymatic glycation, also known as Maillard reaction, plays an important role in the secondary complications of the diabetic pathology and aging, therefore, human serum albumin (HSA) and bovine serum albumin (BSA) were glycated by a conventional method in our laboratory using glucose as the glycating agent. Fluorescence lifetime measurements were carried out with a laser strobe fluorometer equipped with a nitrogen/dye laser and a frequency doubler as a pulsed excitation source. The samples were excited at 295 nm and the emission spectra were recorded at 345 nm. The obtained decay curves were tried for double and triple exponential functions. It has been found that the shorter lifetime increases for glycated proteins as compared with that of the native ones. For example, in the case of glycated BSA the lifetime increased from 1.36 ns to 2.30 ns. Similarly, for HSA, the lifetime increases from 1.58 ns to 2.26 ns. Meanwhile, the longer lifetime changed very slightly for both proteins (from 6.52 ns to 6.72 ns). The increase in the lifetime can be associated with the environmental effect; originated from the attachment of glucose to some lysine residues. A good example is Trp 214 which is in the cage of Lys 225, Lys 212, Lys 233, Lys 205, Lys 500, Lys 199 and Lys 195. If fluorescence lifetime technique is calibrated and properly used it could be employed for assessing glycation of proteins.

  8. Fluorescence lifetime imaging of lipids during 3T3-L1 cell differentiation

    Science.gov (United States)

    Song, Young Sik; Won, Young Jae; Lee, Sang-Hak; Kim, Dug Young

    2014-03-01

    Obesity is becoming a big health problem in these days. Since increased body weight is due to increased number and size of the triglyceride-storing adipocytes, many researchers are working on differentiation conditions and processes of adipocytes. Adipocytes also work as regulators of whole-body energy homeostasis by secreting several proteins that regulate processes as diverse as haemostasis, blood pressure, immune function, angiogenesis and energy balance. 3T3-L1 cells are widely used cell line for studying adipogenesis because it can differentiate into an adipocyte-like phenotype under appropriate conditions. In this paper, we propose an effective fluorescence lifetime imaging technique which can easily distinguish lipids in membrane and those in lipid droplets. Nile red dyes are attached to lipids in 3T3-L1 cells. Fluorescence lifetime images were taken for 2 week during differentiation procedure of 3T3-L1 cells into adipocytes. We used 488 nm pulsed laser with 5MHz repetition rate and emission wavelength is 520 nm of Nile Red fluorescent dye. Results clearly show that the lifetime of Nile red in lipid droplets are smaller than those in cell membrane. Our results suggest that fluorescence lifetime imaging can be a very powerful tool to monitor lipid droplet formation in adipocytes from 3T3-L1 cells.

  9. Fluorescence lifetime of emitters with broad homogeneous linewidths modified in opal photonic crystals

    DEFF Research Database (Denmark)

    Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

    2008-01-01

    We have investigated the dynamics of spontaneous emission from dye molecules embedded in opal photonic crystals. Fluorescence lifetimes of Rhodamine 6G (R6G) dye were measured as a function of both optical frequency and crystal lattice parameter of the polystyrene opals. Due to the broad...

  10. Towards sensitive, high-throughput, biomolecular assays based on fluorescence lifetime

    Science.gov (United States)

    Ioanna Skilitsi, Anastasia; Turko, Timothé; Cianfarani, Damien; Barre, Sophie; Uhring, Wilfried; Hassiepen, Ulrich; Léonard, Jérémie

    2017-09-01

    Time-resolved fluorescence detection for robust sensing of biomolecular interactions is developed by implementing time-correlated single photon counting in high-throughput conditions. Droplet microfluidics is used as a promising platform for the very fast handling of low-volume samples. We illustrate the potential of this very sensitive and cost-effective technology in the context of an enzymatic activity assay based on fluorescently-labeled biomolecules. Fluorescence lifetime detection by time-correlated single photon counting is shown to enable reliable discrimination between positive and negative control samples at a throughput as high as several hundred samples per second.

  11. Time-Domain Fluorescence Lifetime Imaging Techniques Suitable for Solid-State Imaging Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Robert K. Henderson

    2012-05-01

    Full Text Available We have successfully demonstrated video-rate CMOS single-photon avalanche diode (SPAD-based cameras for fluorescence lifetime imaging microscopy (FLIM by applying innovative FLIM algorithms. We also review and compare several time-domain techniques and solid-state FLIM systems, and adapt the proposed algorithms for massive CMOS SPAD-based arrays and hardware implementations. The theoretical error equations are derived and their performances are demonstrated on the data obtained from 0.13 μm CMOS SPAD arrays and the multiple-decay data obtained from scanning PMT systems. In vivo two photon fluorescence lifetime imaging data of FITC-albumin labeled vasculature of a P22 rat carcinosarcoma (BD9 rat window chamber are used to test how different algorithms perform on bi-decay data. The proposed techniques are capable of producing lifetime images with enough contrast.

  12. Azadioxatriangulenium: a long fluorescence lifetime fluorophore for large biomolecule binding assay

    International Nuclear Information System (INIS)

    Sørensen, Thomas Just; Thyrhaug, Erling; Szabelski, Mariusz; Gryczynski, Ignacy; Gryczynski, Zygmunt; Luchowski, Rafal; Laursen, Bo W

    2013-01-01

    Of the many optical bioassays available, sensing by fluorescence anisotropy has great advantages as it provides a sensitive, instrumentally simple, ratiometric method of detection. However, it is hampered by a severe limitation, as the emission lifetime of the label needs to be comparable to the correlation lifetime (tumbling time) of the biomolecule which is labelled. For proteins of moderate size this is on the order of 20–200 ns, which due to practical issues currently limits the choice of labels to the dansyl-type dyes and certain aromatic dyes. These have the significant drawback of UV/blue absorption and emission as well as an often significant solvent sensitivity. Here, we report the synthesis and characterization of a new fluorescent label for high molecular weight biomolecule assay based on the azadioxatriangulenium motif. The NHS ester of the long fluorescence lifetime, red-emitting fluorophore: azadioxatriangulenium (ADOTA-NHS) was conjugated to anti-rabbit Immunoglobulin G (antiIgG). The long fluorescence lifetime was exploited to determine the correlation time of the high molecular weight antibody and its complex with rabbit Immunoglobulin G (IgG) with steady-state fluorescence anisotropy and time-resolved methods: solution phase immuno-assay was performed following either steady-state or time-resolved fluorescence anisotropy. By performing a variable temperature experiment it was determined that the binding of the ligand resulted in an increase in correlation time of more than 75%, and an increase in the steady-state anisotropy of 18%. The results show that the triangulenium class of dyes can be used in anisotropy assay to detect binding events involving biomolecules of far larger size than what is possible with most other red-emitting organic dyes. (paper)

  13. Azadioxatriangulenium: a long fluorescence lifetime fluorophore for large biomolecule binding assay

    Science.gov (United States)

    Just Sørensen, Thomas; Thyrhaug, Erling; Szabelski, Mariusz; Luchowski, Rafal; Gryczynski, Ignacy; Gryczynski, Zygmunt; Laursen, Bo W.

    2013-06-01

    Of the many optical bioassays available, sensing by fluorescence anisotropy has great advantages as it provides a sensitive, instrumentally simple, ratiometric method of detection. However, it is hampered by a severe limitation, as the emission lifetime of the label needs to be comparable to the correlation lifetime (tumbling time) of the biomolecule which is labelled. For proteins of moderate size this is on the order of 20-200 ns, which due to practical issues currently limits the choice of labels to the dansyl-type dyes and certain aromatic dyes. These have the significant drawback of UV/blue absorption and emission as well as an often significant solvent sensitivity. Here, we report the synthesis and characterization of a new fluorescent label for high molecular weight biomolecule assay based on the azadioxatriangulenium motif. The NHS ester of the long fluorescence lifetime, red-emitting fluorophore: azadioxatriangulenium (ADOTA-NHS) was conjugated to anti-rabbit Immunoglobulin G (antiIgG). The long fluorescence lifetime was exploited to determine the correlation time of the high molecular weight antibody and its complex with rabbit Immunoglobulin G (IgG) with steady-state fluorescence anisotropy and time-resolved methods: solution phase immuno-assay was performed following either steady-state or time-resolved fluorescence anisotropy. By performing a variable temperature experiment it was determined that the binding of the ligand resulted in an increase in correlation time of more than 75%, and an increase in the steady-state anisotropy of 18%. The results show that the triangulenium class of dyes can be used in anisotropy assay to detect binding events involving biomolecules of far larger size than what is possible with most other red-emitting organic dyes.

  14. Azadioxatriangulenium (ADOTA+): A long fluorescence lifetime fluorophore for large biomolecule binding assay

    Science.gov (United States)

    Sørensen, Thomas Just; Thyrhaug, Erling; Szabelski, Mariusz; Luchowski, Rafal; Gryczynski, Ignacy; Gryczynski, Zygmunt; Laursen, Bo W.

    2013-01-01

    Of the many optical bioassays available, sensing by fluorescence anisotropy have great advantages as it provides a sensitive, instrumentally simple, ratiometric method of detection. However, it is hampered by a severe limitation as the emission lifetime of the label needs to be comparable to the correlation lifetime (tumbling time) of the biomolecule which is labelled. For proteins of moderate size this is in the order of 20–200 ns, which due to practical issues currently limits the choice of labels to the dansyl-type dyes and certain aromatics dyes. These have the significant drawback of UV/blue absorption and emission as well as an often significant solvent sensitivity. Here, we report the synthesis and characterization of a new fluorescent label for high molecular weight biomolecules assay based on the azadioxatriangulenium motif. The NHS ester of the long fluorescence lifetime, red emitting fluorophore: azadioxatriangulenium (ADOTA-NHS) was conjugated to anti-rabbit Immunoglobulin G (antiIgG). The long fluorescence lifetime was exploited to determine the correlation time of the high molecular weight antibody and its complex with rabbit Immuniglobulin G (IgG) with steady-state fluorescence anisotropy and time-resolved methods: solution phase immuno-assay was performed following either steady-state or time-resolved fluorescence anisotropy. By performing a variable temperature experiment it was determined that the binding of the ligand resulted in an increase in correlation time by more than 75 %, and a change in the steady-state anisotropy increase of 18%. The results show that the triangulenium class of dyes can be used in anisotropy assay for detecting binding events involving biomolecules of far larger size than what is possible with the other red emitting organic dyes. PMID:24058730

  15. Online multispectral fluorescence lifetime values estimation and overlay onto tissue white-light video frames

    Science.gov (United States)

    Gorpas, Dimitris; Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Marcu, Laura

    2016-03-01

    Fluorescence lifetime imaging has been shown to be a robust technique for biochemical and functional characterization of tissues and to present great potential for intraoperative tissue diagnosis and guidance of surgical procedures. We report a technique for real-time mapping of fluorescence parameters (i.e. lifetime values) onto the location from where the fluorescence measurements were taken. This is achieved by merging a 450 nm aiming beam generated by a diode laser with the excitation light in a single delivery/collection fiber and by continuously imaging the region of interest with a color CMOS camera. The interrogated locations are then extracted from the acquired frames via color-based segmentation of the aiming beam. Assuming a Gaussian profile of the imaged aiming beam, the segmentation results are fitted to ellipses that are dynamically scaled at the full width of three automatically estimated thresholds (50%, 75%, 90%) of the Gaussian distribution's maximum value. This enables the dynamic augmentation of the white-light video frames with the corresponding fluorescence decay parameters. A fluorescence phantom and fresh tissue samples were used to evaluate this method with motorized and hand-held scanning measurements. At 640x512 pixels resolution the area of interest augmented with fluorescence decay parameters can be imaged at an average 34 frames per second. The developed method has the potential to become a valuable tool for real-time display of optical spectroscopy data during continuous scanning applications that subsequently can be used for tissue characterization and diagnosis.

  16. Rotational multispectral fluorescence lifetime imaging and intravascular ultrasound: bimodal system for intravascular applications

    Science.gov (United States)

    Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Gorpas, Dimitris; Fatakdawala, Hussain; Marcu, Laura

    2014-01-01

    Abstract. We report the development and validation of a hybrid intravascular diagnostic system combining multispectral fluorescence lifetime imaging (FLIm) and intravascular ultrasound (IVUS) for cardiovascular imaging applications. A prototype FLIm system based on fluorescence pulse sampling technique providing information on artery biochemical composition was integrated with a commercial IVUS system providing information on artery morphology. A customized 3-Fr bimodal catheter combining a rotational side-view fiberoptic and a 40-MHz IVUS transducer was constructed for sequential helical scanning (rotation and pullback) of tubular structures. Validation of this bimodal approach was conducted in pig heart coronary arteries. Spatial resolution, fluorescence detection efficiency, pulse broadening effect, and lifetime measurement variability of the FLIm system were systematically evaluated. Current results show that this system is capable of temporarily resolving the fluorescence emission simultaneously in multiple spectral channels in a single pullback sequence. Accurate measurements of fluorescence decay characteristics from arterial segments can be obtained rapidly (e.g., 20 mm in 5 s), and accurate co-registration of fluorescence and ultrasound features can be achieved. The current finding demonstrates the compatibility of FLIm instrumentation with in vivo clinical investigations and its potential to complement conventional IVUS during catheterization procedures. PMID:24898604

  17. A fast global fitting algorithm for fluorescence lifetime imaging microscopy based on image segmentation.

    Science.gov (United States)

    Pelet, S; Previte, M J R; Laiho, L H; So, P T C

    2004-10-01

    Global fitting algorithms have been shown to improve effectively the accuracy and precision of the analysis of fluorescence lifetime imaging microscopy data. Global analysis performs better than unconstrained data fitting when prior information exists, such as the spatial invariance of the lifetimes of individual fluorescent species. The highly coupled nature of global analysis often results in a significantly slower convergence of the data fitting algorithm as compared with unconstrained analysis. Convergence speed can be greatly accelerated by providing appropriate initial guesses. Realizing that the image morphology often correlates with fluorophore distribution, a global fitting algorithm has been developed to assign initial guesses throughout an image based on a segmentation analysis. This algorithm was tested on both simulated data sets and time-domain lifetime measurements. We have successfully measured fluorophore distribution in fibroblasts stained with Hoechst and calcein. This method further allows second harmonic generation from collagen and elastin autofluorescence to be differentiated in fluorescence lifetime imaging microscopy images of ex vivo human skin. On our experimental measurement, this algorithm increased convergence speed by over two orders of magnitude and achieved significantly better fits. Copyright 2004 Biophysical Society

  18. Fluorescence lifetime spectroscopy in multiple-scattering environments: an application to biotechnology

    Science.gov (United States)

    Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio

    1999-07-01

    Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.

  19. Fluorescence lifetime imaging of endogenous molecules in live mouse cancer models (Conference Presentation)

    Science.gov (United States)

    Svindrych, Zdenek; Wang, Tianxiong; Hu, Song; Periasamy, Ammasi

    2017-02-01

    NADH and FAD are important endogenous fluorescent coenzymes participating in key enzymatic reactions of cellular metabolism. While fluorescence intensities of NADH and FAD have been used to determine the redox state of cells and tissues, this simple approach breaks down in the case of deep-tissue intravital imaging due to depth- and wavelength-dependent light absorption and scattering. To circumvent this limitation, our research focuses on fluorescence lifetimes of two-photon excited NADH and FAD emission to study the metabolic state of live tissues. In our custom-built scanning microscope we combine tunable femtosecond Ti:sapphire laser (operating at 740 nm for NADH excitation and 890 nm for FAD excitation), two GaAsP hybrid detectors for registering individual fluorescence photons and two Becker and Hickl time correlator boards for high precision lifetime measurements. Together with our rigorous FLIM analysis approach (including image segmentation, multi-exponential decay fitting and detailed statistical analysis) we are able to detect metabolic changes in cancer xenografts (human pancreatic cancer MPanc96 cells injected subcutaneously into the ear of an immunodeficient nude mouse), relative to surrounding healthy tissue. Advantageously, with the same instrumentation we can also take high-resolution and high-contrast images of second harmonic signal (SHG) originating from collagen fibers of both the healthy skin and the growing tumor. The combination of metabolic measurements (NADH and FAD lifetime) and morphological information (collagen SHG) allows us to follow the tumor growth in live mouse model and the changes in tumor microenvironment.

  20. In Vivo Fluorescence Lifetime Imaging Monitors Binding of Specific Probes to Cancer Biomarkers

    Science.gov (United States)

    Ardeshirpour, Yasaman; Chernomordik, Victor; Zielinski, Rafal; Capala, Jacek; Griffiths, Gary; Vasalatiy, Olga; Smirnov, Aleksandr V.; Knutson, Jay R.; Lyakhov, Ilya; Achilefu, Samuel; Gandjbakhche, Amir; Hassan, Moinuddin

    2012-01-01

    One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells. Particularly, recent advances in Monoclonal Antibodies (MAB) as primary-specific drugs targeting tumor receptors show that their efficacy depends strongly on characterization of tumor biomarkers. Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention. In this study we have demonstrated for the first time in live animals that the fluorescence lifetime can be used to detect the binding of targeted optical probes to the extracellular receptors on tumor cells in vivo. The rationale was that fluorescence lifetime of a specific probe is sensitive to local environment and/or affinity to other molecules. We attached Near-InfraRed (NIR) fluorescent probes to Human Epidermal Growth Factor 2 (HER2/neu)-specific Affibody molecules and used our time-resolved optical system to compare the fluorescence lifetime of the optical probes that were bound and unbound to tumor cells in live mice. Our results show that the fluorescence lifetime changes in our model system delineate HER2 receptor bound from the unbound probe in vivo. Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the “image and treat” concept, especially for early evaluation of the efficacy of the therapy. PMID:22384092

  1. In vivo fluorescence lifetime imaging monitors binding of specific probes to cancer biomarkers.

    Directory of Open Access Journals (Sweden)

    Yasaman Ardeshirpour

    Full Text Available One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells. Particularly, recent advances in Monoclonal Antibodies (MAB as primary-specific drugs targeting tumor receptors show that their efficacy depends strongly on characterization of tumor biomarkers. Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention. In this study we have demonstrated for the first time in live animals that the fluorescence lifetime can be used to detect the binding of targeted optical probes to the extracellular receptors on tumor cells in vivo. The rationale was that fluorescence lifetime of a specific probe is sensitive to local environment and/or affinity to other molecules. We attached Near-InfraRed (NIR fluorescent probes to Human Epidermal Growth Factor 2 (HER2/neu-specific Affibody molecules and used our time-resolved optical system to compare the fluorescence lifetime of the optical probes that were bound and unbound to tumor cells in live mice. Our results show that the fluorescence lifetime changes in our model system delineate HER2 receptor bound from the unbound probe in vivo. Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the "image and treat" concept, especially for early evaluation of the efficacy of the therapy.

  2. Efficacy of photodynamic therapy against larvae of Aedes aegypti: confocal microscopy and fluorescence-lifetime imaging

    Science.gov (United States)

    de Souza, L. M.; Pratavieira, S.; Inada, N. M.; Kurachi, C.; Corbi, J.; Guimarães, F. E. G.; Bagnato, V. S.

    2014-03-01

    Recently a few demonstration on the use of Photodynamic Reaction as possibility to eliminate larvae that transmit diseases for men has been successfully demonstrated. This promising tool cannot be vastly used due to many problems, including the lake of investigation concerning the mechanisms of larvae killing as well as security concerning the use of photosensitizers in open environment. In this study, we investigate some of the mechanisms in which porphyrin (Photogem) is incorporated on the Aedes aegypti larvae previously to illumination and killing. Larvae at second instar were exposed to the photosensitizer and after 30 minutes imaged by a confocal fluorescence microscope. It was observed the presence of photosensitizer in the gut and at the digestive tract of the larva. Fluorescence-Lifetime Imaging showed greater photosensitizer concentration in the intestinal wall of the samples, which produces a strong decrease of the Photogem fluorescence lifetime. For Photodynamic Therapy exposition to different light doses and concentrations of porphyrin were employed. Three different light sources (LED, Fluorescent lamp, Sun light) also were tested. Sun light and fluorescent lamp shows close to 100% of mortality after 24 hrs. of illumination. These results indicate the potential use of photodynamic effect against the LARVAE of Aedes aegypti.

  3. In vivo imaging of cerebral energy metabolism with two-photon fluorescence lifetime microscopy of NADH.

    Science.gov (United States)

    Yaseen, Mohammad A; Sakadžić, Sava; Wu, Weicheng; Becker, Wolfgang; Kasischke, Karl A; Boas, David A

    2013-02-01

    Minimally invasive, specific measurement of cellular energy metabolism is crucial for understanding cerebral pathophysiology. Here, we present high-resolution, in vivo observations of autofluorescence lifetime as a biomarker of cerebral energy metabolism in exposed rat cortices. We describe a customized two-photon imaging system with time correlated single photon counting detection and specialized software for modeling multiple-component fits of fluorescence decay and monitoring their transient behaviors. In vivo cerebral NADH fluorescence suggests the presence of four distinct components, which respond differently to brief periods of anoxia and likely indicate different enzymatic formulations. Individual components show potential as indicators of specific molecular pathways involved in oxidative metabolism.

  4. Design, construction, and validation of a rotary multifunctional intravascular diagnostic catheter combining multispectral fluorescence lifetime imaging and intravascular ultrasound.

    Science.gov (United States)

    Bec, Julien; Xie, Hongtao; Yankelevich, Diego R; Zhou, Feifei; Sun, Yang; Ghata, Narugopal; Aldredge, Ralph; Marcu, Laura

    2012-10-01

    We report the development and validation of an intravascular rotary catheter for bimodal interrogation of arterial pathologies. This is based on a point-spectroscopy scanning time-resolved fluorescence spectroscopy technique enabling reconstruction of fluorescence lifetime images (FLIm) and providing information on arterial intima composition and intravascular ultrasound (IVUS) providing information on arterial wall morphology. The catheter design allows for independent rotation of the ultrasonic and optical channels within an 8 Fr outer diameter catheter sheath and integrates a low volume flushing channel for blood removal in the optical pathways. In the current configuration, the two channels consist of (a) a standard 3 Fr IVUS catheter with single element transducer (40 MHz) and (b) a side-viewing fiber optic (400 μm core). Experiments conducted in tissue phantoms showed the ability of the catheter to operate in an intraluminal setting and to generate coregistered FLIm and IVUS in one pull-back scan. Current results demonstrate the feasibility of the catheter for simultaneous bimodal interrogation of arterial lumen and for generation of robust fluorescence lifetime data under IVUS guidance. These results facilitate further development of a FLIm-IVUS technique for intravascular diagnosis of atherosclerotic cardiovascular diseases including vulnerable plaques.

  5. Fluorescence lifetime measurement with confocal endomicroscopy for direct analysis of tissue biochemistry in vivo

    Directory of Open Access Journals (Sweden)

    Youngjae Won

    2016-08-01

    Full Text Available Confocal endomicroscopy is a powerful tool for in vivo real-time imaging at cellular resolution inside a living body without tissue resection. Microscopic fluorescence lifetime measurement can provide information about localized biochemical conditions such as pH and the concentrations of oxygen and calcium. We hypothesized that combining these techniques could assist accurate cancer discrimination by providing both biochemical and morphological information. We designed a dual-mode experimental setup for confocal endomicroscopic imaging and fluorescence lifetime measurement and applied it to a mouse xenograft model of activated human pancreatic cancer generated by subcutaneous injection of AsPC-1 tumor cells. Using this method with pH-sensitive sodium fluorescein injection, we demonstrated discrimination between normal and cancerous tissues in a living mouse. With further development, this method may be useful for clinical cancer detection.

  6. Label-free identification of macrophage phenotype by fluorescence lifetime imaging microscopy

    Science.gov (United States)

    Alfonso-García, Alba; Smith, Tim D.; Datta, Rupsa; Luu, Thuy U.; Gratton, Enrico; Potma, Eric O.; Liu, Wendy F.

    2016-04-01

    Macrophages adopt a variety of phenotypes that are a reflection of the many functions they perform as part of the immune system. In particular, metabolism is a phenotypic trait that differs between classically activated, proinflammatory macrophages, and alternatively activated, prohealing macrophages. Inflammatory macrophages have a metabolism based on glycolysis while alternatively activated macrophages generally rely on oxidative phosphorylation to generate chemical energy. We employ this shift in metabolism as an endogenous marker to identify the phenotype of individual macrophages via live-cell fluorescence lifetime imaging microscopy (FLIM). We demonstrate that polarized macrophages can be readily discriminated with the aid of a phasor approach to FLIM, which provides a fast and model-free method for analyzing fluorescence lifetime images.

  7. Single pulse two photon fluorescence lifetime imaging (SP-FLIM) with MHz pixel rate.

    Science.gov (United States)

    Eibl, Matthias; Karpf, Sebastian; Weng, Daniel; Hakert, Hubertus; Pfeiffer, Tom; Kolb, Jan Philip; Huber, Robert

    2017-07-01

    Two-photon-excited fluorescence lifetime imaging microscopy (FLIM) is a chemically specific 3-D sensing modality providing valuable information about the microstructure, composition and function of a sample. However, a more widespread application of this technique is hindered by the need for a sophisticated ultra-short pulse laser source and by speed limitations of current FLIM detection systems. To overcome these limitations, we combined a robust sub-nanosecond fiber laser as the excitation source with high analog bandwidth detection. Due to the long pulse length in our configuration, more fluorescence photons are generated per pulse, which allows us to derive the lifetime with a single excitation pulse only. In this paper, we show high quality FLIM images acquired at a pixel rate of 1 MHz. This approach is a promising candidate for an easy-to-use and benchtop FLIM system to make this technique available to a wider research community.

  8. Exciton-polaron quenching in organic thin-film transistors studied by fluorescence lifetime imaging microscopy

    DEFF Research Database (Denmark)

    Jensen, Per Baunegaard With; Leißner, Till; Osadnik, Andreas

    Organic semiconductors show great potential in electronic and optical applications. However, a major challenge is the degradation of the semiconductor materials that cause a reduction in device performance. Here, we present our investigations of Organic Thin Film Transistors (OTFT) based...... that correlates with the local charge density indicates a pronounced exciton quenching by the injected charges. Subsequent FLIM measurements on previously biased OTFT devices show a general decrease in fluorescence lifetime suggesting degradation of the organic semiconductor. This is correlated with the results...

  9. Diagnosis of basal cell carcinoma by two photon excited fluorescence combined with lifetime imaging

    Science.gov (United States)

    Fan, Shunping; Peng, Xiao; Liu, Lixin; Liu, Shaoxiong; Lu, Yuan; Qu, Junle

    2014-02-01

    Basal cell carcinoma (BCC) is the most common type of human skin cancer. The traditional diagnostic procedure of BCC is histological examination with haematoxylin and eosin staining of the tissue biopsy. In order to reduce complexity of the diagnosis procedure, a number of noninvasive optical methods have been applied in skin examination, for example, multiphoton tomography (MPT) and fluorescence lifetime imaging microscopy (FLIM). In this study, we explored two-photon optical tomography of human skin specimens using two-photon excited autofluorescence imaging and FLIM. There are a number of naturally endogenous fluorophores in skin sample, such as keratin, melanin, collagen, elastin, flavin and porphyrin. Confocal microscopy was used to obtain structures of the sample. Properties of epidermic and cancer cells were characterized by fluorescence emission spectra, as well as fluorescence lifetime imaging. Our results show that two-photon autofluorescence lifetime imaging can provide accurate optical biopsies with subcellular resolution and is potentially a quantitative optical diagnostic method in skin cancer diagnosis.

  10. Assessment of post-implantation integration of engineered tissues using fluorescence lifetime spectroscopy

    Science.gov (United States)

    Elahi, Sakib F.; Lee, Seung Y.; Lloyd, William R.; Chen, Leng-Chun; Kuo, Shiuhyang; Zhou, Ying; Kim, Hyungjin M.; Kennedy, Robert; Marcelo, Cynthia; Feinberg, Stephen E.; Mycek, Mary-Ann

    2018-02-01

    Clinical translation of engineered tissue constructs requires noninvasive methods to assess construct health and viability after implantation in patients. However, current practices to monitor post-implantation construct integration are either qualitative (visual assessment) or destructive (tissue histology). As label-free fluorescence lifetime sensing can noninvasively characterize pre-implantation construct viability, we employed a handheld fluorescence lifetime spectroscopy probe to quantitatively and noninvasively assess tissue constructs that were implanted in a murine model. We designed the system to be suitable for intravital measurements: portability, localization with precise maneuverability, and rapid data acquisition. Our model tissue constructs were manufactured from primary human cells to simulate patient variability and were stressed to create a range of health states. Secreted amounts of three cytokines that relate to cellular viability were measured in vitro to assess pre-implantation construct health. In vivo optical sensing assessed tissue integration of constructs at one-week and three-weeks post-implantation. At one-week post-implantation, optical parameters correlated with in vitro pre-implantation secretion levels of all three cytokines (p clinical optical diagnostic tools based on label-free fluorescence lifetime sensing of endogenous tissue fluorophores could noninvasively monitor post-implantation integration of engineered tissues.

  11. Fluorescence intensity and lifetime-based cyanide sensitive probes for physiological safeguard

    International Nuclear Information System (INIS)

    Badugu, Ramachandram; Lakowicz, Joseph R.; Geddes, Chris D.

    2004-01-01

    We characterize six new fluorescent probes that show both intensity and lifetime changes in the presence of free uncomplexed aqueous cyanide, allowing for fluorescence based cyanide sensing up to physiological safeguard levels, i.e. 2 to the anionic R-B - (CN) 3 form, a new cyanide binding mechanism which we have recently reported. The presence of an electron deficient quaternary heterocyclic nitrogen nucleus, and the electron rich cyanide bound form, provides for the intensity changes observed. We have determined the disassociation constants of the probes to be in the range ∼15-84 μM 3 . In addition we have synthesized control compounds which do not contain the boronic acid moiety, allowing for a rationale of the cyanide responses between the probe isomers to be made. The lifetime of the cyanide bound probes are significantly shorter than the free R-B(OH) 2 probe forms, providing for the opportunity of lifetime based cyanide sensing up to physiologically lethal levels. Finally, while fluorescent probes containing the boronic acid moiety have earned a well-deserved reputation for monosaccharide sensing, we show that strong bases such as CN - and OH - preferentially bind as compared to glucose, enabling the potential use of these probes for cyanide safeguard and determination in physiological fluids, especially given that physiologies do not experience any notable changes in pH

  12. Multimodal optical coherence tomography and fluorescence lifetime imaging with interleaved excitation sources for simultaneous endogenous and exogenous fluorescence.

    Science.gov (United States)

    Shrestha, Sebina; Serafino, Michael J; Rico-Jimenez, Jesus; Park, Jesung; Chen, Xi; Zhaorigetu, Siqin; Walton, Brian L; Jo, Javier A; Applegate, Brian E

    2016-09-01

    Multimodal imaging probes a variety of tissue properties in a single image acquisition by merging complimentary imaging technologies. Exploiting synergies amongst the data, algorithms can be developed that lead to better tissue characterization than could be accomplished by the constituent imaging modalities taken alone. The combination of optical coherence tomography (OCT) with fluorescence lifetime imaging microscopy (FLIM) provides access to detailed tissue morphology and local biochemistry. The optical system described here merges 1310 nm swept-source OCT with time-domain FLIM having excitation at 355 and 532 nm. The pulses from 355 and 532 nm lasers have been interleaved to enable simultaneous acquisition of endogenous and exogenous fluorescence signals, respectively. The multimodal imaging system was validated using tissue phantoms. Nonspecific tagging with Alexa Flour 532 in a Watanbe rabbit aorta and active tagging of the LOX-1 receptor in human coronary artery, demonstrate the capacity of the system for simultaneous acquisition of OCT, endogenous FLIM, and exogenous FLIM in tissues.

  13. Differentiation of ocular fundus fluorophores by fluorescence lifetime imaging using multiple excitation and emission wavelengths

    Science.gov (United States)

    Hammer, M.; Schweitzer, D.; Schenke, S.; Becker, W.; Bergmann, A.

    2006-10-01

    Ocular fundus autofluorescence imaging has been introduced into clinical diagnostics recently. It is in use for the observation of the age pigment lipofuscin, a precursor of age - related macular degeneration (AMD). But other fluorophores may be of interest too: The redox pair FAD - FADH II provides information on the retinal energy metabolism, advanced glycation end products (AGE) indicate protein glycation associated with pathologic processes in diabetes as well as AMD, and alterations in the fluorescence of collagen and elastin in connective tissue give us the opportunity to observe fibrosis by fluorescence imaging. This, however, needs techniques able to differentiate particular fluorophores despite limited permissible ocular exposure as well as excitation wavelength (limited by the transmission of the human ocular lens to >400 nm). We present an ophthalmic laser scanning system (SLO), equipped with picosecond laser diodes (FWHM 100 ps, 446 nm or 468 nm respectively) and time correlated single photon counting (TCSPC) in two emission bands (500 - 560 nm and 560 - 700 nm). The decays were fitted by a bi-exponential model. Fluorescence spectra were measured by a fluorescence spectrometer fluorolog. Upon excitation at 446 nm, the fluorescence of AGE, FAD, and lipofuscin were found to peak at 503 nm, 525 nm, and 600 nm respectively. Accordingly, the statistical distribution of the fluorescence decay times was found to depend on the different excitation wavelengths and emission bands used. The use of multiple excitation and emission wavelengths in conjunction with fluorescence lifetime imaging allows us to discriminate between intrinsic fluorophores of the ocular fundus. Taken together with our knowledge on the anatomical structure of the fundus, these findings suggest an association of the short, middle and long fluorescence decay time to the retinal pigment epithelium, the retina, and connective tissue respectively.

  14. Fluorescence lifetime microscopy for monitoring cell adhesion using metal induced energy transfer

    Science.gov (United States)

    Hwang, Wonsang; Seo, JinWon; Song, Jun ho; Kim, DongEun; Won, YoungJae; Choi, In-Hong; Yoo, Kyung-Hwa; Kim, Dug Young

    2018-02-01

    A precise control and a reliable monitoring tool for the adhesion properties of a cell are very important in atherosclerosis studies. If endothelial cells in contact with the intracellular membrane are not attached securely, low-density lipoprotein (LDL) particles can enter into the inner membrane. It is therefore necessary to measure conditions under which endothelial cell detachment occurs. When a cell is attached to a metal thin film, the lifetime of a fluorescence probe attached to the membrane of the cell is reduced by the metal-induced energy transfer (MIET). Fluorescence lifetime imaging microscopy (FLIM) is used to monitor the attachment condition of a cell to a metal surface using FRET. However, this requires high numerical aperture (NA) objective lens because axial confocal resolution must be smaller than the cell thickness. This requirement limits the field of view of the measurement specimen. In this study we provides a new method which can measure adhesion properties of endothelial cells even with a low NA objective lens by resolving two lifetime components in FLIM.

  15. Xanthophyll cycle-dependent quenching of photosystem II chlorophyll a fluorescence: Formation of a quenching complex with a short fluorescence lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, A.M.; Hazlett, T.L.; Govindjee [Univ. of Illinois, Urbana, IL (United States)

    1995-03-14

    Excess light triggers protective nonradiative dissipation of excitation energy in photosystem II through the formation of a trans-thylakoid pH gradient that in turn stimulates formation of zeaxanthin and antheraxanthin. These xanthophylls when combined with protonation of antenna pigment-protein complexes may increase nonradiative dissipation and, thus, quench chlorophyll a fluorescence. Here we measured, in parallel, the chlorophyll a fluorescence lifetime and intensity to understand the mechanism of this process. Increasing the xanthophyll concentration in the presence of a pH gradient (quenched conditions) decreases the fractional intensity of a fluorescence lifetime component centered at {approx}2 ns and increases a component at {approx}0.4 ns. Uncoupling the pH gradient (unquenched conditions) eliminates the 0.4-ns component. Changes in the xanthophyll concentration do not significantly affect the fluorescence lifetimes in either the quenched or unquenched sample conditions. However, there are differences in fluorescence lifetimes between the quenched and unquenched states that are due to pH-related, but nonxanthophyll-related, processes. Quenching of the maximal fluorescence intensity correlates with both the xanthophyll concentration and the fractional intensity of the 0.4-ns component. The unchanged fluorescence lifetimes and the proportional quenching of the maximal and dark-level fluorescence intensities indicate that the xanthophyllact on antenna, not reaction center processes. Further, the fluorescence quenching is interpreted as the combined effect of the pH gradient and xanthophyll concentration, resulting in the formation of a quenching complex with a short ({approx}0.4 ns) fluorescence lifetime. 33 refs., 6 figs., 2 tabs.

  16. Fluorescence lifetime microscopy of NADH distinguishes alterations in cerebral metabolism in vivo.

    Science.gov (United States)

    Yaseen, Mohammad A; Sutin, Jason; Wu, Weicheng; Fu, Buyin; Uhlirova, Hana; Devor, Anna; Boas, David A; Sakadžić, Sava

    2017-05-01

    Evaluating cerebral energy metabolism at microscopic resolution is important for comprehensively understanding healthy brain function and its pathological alterations. Here, we resolve specific alterations in cerebral metabolism in vivo in Sprague Dawley rats utilizing minimally-invasive 2-photon fluorescence lifetime imaging (2P-FLIM) measurements of reduced nicotinamide adenine dinucleotide (NADH) fluorescence. Time-resolved fluorescence lifetime measurements enable distinction of different components contributing to NADH autofluorescence. Ostensibly, these components indicate different enzyme-bound formulations of NADH. We observed distinct variations in the relative proportions of these components before and after pharmacological-induced impairments to several reactions involved in glycolytic and oxidative metabolism. Classification models were developed with the experimental data and used to predict the metabolic impairments induced during separate experiments involving bicuculline-induced seizures. The models consistently predicted that prolonged focal seizure activity results in impaired activity in the electron transport chain, likely the consequence of inadequate oxygen supply. 2P-FLIM observations of cerebral NADH will help advance our understanding of cerebral energetics at a microscopic scale. Such knowledge will aid in our evaluation of healthy and diseased cerebral physiology and guide diagnostic and therapeutic strategies that target cerebral energetics.

  17. Carrier Lifetimes in Fluorescent 6H-SiC for LEDs Application

    DEFF Research Database (Denmark)

    Grivickas, Vytautas; Gulbinas, Karolis; Jokubavičius, Valdas

    Recently it was shown a new approach based on all-semiconductor material technology which is composed with a near ultra-violet GaN LED excitation source and fluorescent silicon carbide (f-6H-SiC) substrate which generates a visible broad spectral light by N and B dopants and an efficient donor...... to acceptor pair recombination [1,2]. This combination can achieve higher electric-light conversion efficiency and high color rendering in comparison with today’s used blue GaN LED based and phosphors. The devices are promising candidates for general lightning applications and may obtain stability...... under co-linear and orthogonal probe geometry was used to measure carrier lifetimes in the layers under variable injection conditions. Same results are shown in Fig. 1 exaggerating the fact that longer electron lifetime responsible for higher emission and n-type doping should prevail the p-type doping...

  18. Monitoring macular pigment changes in macular holes using fluorescence lifetime imaging ophthalmoscopy.

    Science.gov (United States)

    Sauer, Lydia; Peters, Sven; Schmidt, Johanna; Schweitzer, Dietrich; Klemm, Matthias; Ramm, Lisa; Augsten, Regine; Hammer, Martin

    2017-08-01

    To investigate the impact of macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo by characterizing full-thickness idiopathic macular holes (MH) and macular pseudo-holes (MPH). A total of 37 patients with MH and 52 with MPH were included. Using the fluorescence lifetime imaging ophthalmoscope (FLIO), based on a Heidelberg Engineering Spectralis system, a 30° retinal field was investigated. FAF decays were detected in a short (498-560 nm; ch1) and long (560-720 nm; ch2) wavelength channel. τ m , the mean fluorescence lifetime, was calculated from a three-exponential approximation of the FAF decays. Macular coherence tomography scans were recorded, and macular pigment's optical density (MPOD) was measured (one-wavelength reflectometry). Two MH subgroups were analysed according to the presence or absence of an operculum above the MH. A total of 17 healthy fellow eyes were included. A longitudinal FAF decay examination was conducted in nine patients, which were followed up after surgery and showed a closed MH. In MH without opercula, significant τ m differences (p hole area (MHa) and surrounding areas (MHb) (ch1: MHa 238 ± 64 ps, MHb 181 ± 78 ps; ch2: MHa 275 ± 49 ps, MHb 223 ± 48 ps), as well as between MHa and healthy eyes or closed MH. Shorter τ m , adjacent to the hole, can be assigned to areas with equivalently higher MPOD. Opercula containing MP also show short τ m . In MPH, the intactness of the Hele fibre layer is associated with shortest τ m . Shortest τ m originates from MP-containing retinal layers, especially from the Henle fibre layer. Fluorescence lifetime imaging ophthalmoscope (FLIO) provides information on the MP distribution, the pathogenesis and topology of MH. Macular pigment (MP) fluorescence may provide a biomarker for monitoring pathological changes in retinal diseases. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  19. Fluorescence lifetime imaging of microviscosity changes during ER autophagy in live cells

    Science.gov (United States)

    He, Ying; Samanta, Soham; Gong, Wanjun; Liu, Wufan; Pan, Wenhui; Yang, Zhigang; Qu, Junle

    2018-02-01

    Unfolded or misfolded protein accumulation inside Endoplasmic Reticulum (ER) will cause ER stress and subsequently will activate cellular autophagy to release ER stress, which would ultimately result in microviscosity changes. However, even though, it is highly significant to gain a quantitative assessment of microviscosity changes during ER autophagy to study ER stress and autophagy behaviors related diseases, it has rarely been reported yet. In this work, we have reported a BODIPY based fluorescent molecular rotor that can covalently bind with vicinal dithiols containing nascent proteins in ER and hence can result in ER stress through the inhibition of the folding of nascent proteins. The change in local viscosity, caused by the release of the stress in cells through autophagy, was quantified by the probe using fluorescence lifetime imaging. This work basically demonstrates the possibility of introducing synthetic chemical probe as a promising tool to diagnose ER-viscosity-related diseases.

  20. Fluorescence lifetime components reveal kinetic intermediate states upon equilibrium denaturation of carbonic anhydrase II.

    Science.gov (United States)

    Nemtseva, Elena V; Lashchuk, Olesya O; Gerasimova, Marina A; Melnik, Tatiana N; Nagibina, Galina S; Melnik, Bogdan S

    2017-12-21

    In most cases, intermediate states of multistage folding proteins are not 'visible' under equilibrium conditions but are revealed in kinetic experiments. Time-resolved fluorescence spectroscopy was used in equilibrium denaturation studies. The technique allows for detecting changes in the conformation and environment of tryptophan residues in different structural elements of carbonic anhydrase II which in its turn has made it possible to study the intermediate states of carbonic anhydrase II under equilibrium conditions. The results of equilibrium and kinetic experiments using wild-type bovine carbonic anhydrase II and its mutant form with the substitution of leucine for alanine at position 139 (L139A) were compared. The obtained lifetime components of intrinsic tryptophan fluorescence allowed for revealing that, the same as in kinetic experiments, under equilibrium conditions the unfolding of carbonic anhydrase II ensues through formation of intermediate states.

  1. CVD grown 2D MoS{sub 2} layers: A photoluminescence and fluorescence lifetime imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Oezden, Ayberk; Madenoglu, Buesra [Department of Materials Science and Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey); Sar, Hueseyin; Ay, Feridun; Perkgoez, Nihan Kosku [Department of Electrical and Electronics Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey); Yeltik, Aydan [Department of Physics, UNAM Institute of Materials Science and Nanotechnology, Bilkent University, Ankara (Turkey); Sevik, Cem [Department of Mechanical Engineering, Faculty of Engineering, Anadolu University, Eskisehir (Turkey)

    2016-11-15

    In this letter, we report on the fluorescence lifetime imaging and accompanying photoluminescence properties of a chemical vapour deposition (CVD) grown atomically thin material, MoS{sub 2}. μ-Raman, μ-photoluminescence (PL) and fluorescence lifetime imaging microscopy (FLIM) are utilized to probe the fluorescence lifetime and photoluminescence properties of individual flakes of MoS{sub 2} films. Usage of these three techniques allows identification of the grown layers, grain boundaries, structural defects and their relative effects on the PL and fluorescence lifetime spectra. Our investigation on individual monolayer flakes reveals a clear increase of the fluorescence lifetime from 0.3 ns to 0.45 ns at the edges with respect to interior region. On the other hand, investigation of the film layer reveals quenching of PL intensity and lifetime at the grain boundaries. These results could be important for applications where the activity of edges is important such as in photocatalytic water splitting. Finally, it has been demonstrated that PL mapping and FLIM are viable techniques for the investigation of the grain-boundaries. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

    Directory of Open Access Journals (Sweden)

    Zuzana eBurdikova

    2015-03-01

    Full Text Available Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g. pH, redox potential due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM. In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

  3. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging.

    Science.gov (United States)

    Burdikova, Zuzana; Svindrych, Zdenek; Pala, Jan; Hickey, Cian D; Wilkinson, Martin G; Panek, Jiri; Auty, Mark A E; Periasamy, Ammasi; Sheehan, Jeremiah J

    2015-01-01

    Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

  4. GPU accelerated real-time confocal fluorescence lifetime imaging microscopy (FLIM) based on the analog mean-delay (AMD) method

    Science.gov (United States)

    Kim, Byungyeon; Park, Byungjun; Lee, Seungrag; Won, Youngjae

    2016-01-01

    We demonstrated GPU accelerated real-time confocal fluorescence lifetime imaging microscopy (FLIM) based on the analog mean-delay (AMD) method. Our algorithm was verified for various fluorescence lifetimes and photon numbers. The GPU processing time was faster than the physical scanning time for images up to 800 × 800, and more than 149 times faster than a single core CPU. The frame rate of our system was demonstrated to be 13 fps for a 200 × 200 pixel image when observing maize vascular tissue. This system can be utilized for observing dynamic biological reactions, medical diagnosis, and real-time industrial inspection. PMID:28018724

  5. Direct Vpr-Vpr Interaction in Cells monitored by two Photon Fluorescence Correlation Spectroscopy and Fluorescence Lifetime Imaging

    Directory of Open Access Journals (Sweden)

    Mély Yves

    2008-09-01

    Full Text Available Abstract Background The human immunodeficiency virus type 1 (HIV-1 encodes several regulatory proteins, notably Vpr which influences the survival of the infected cells by causing a G2/M arrest and apoptosis. Such an important role of Vpr in HIV-1 disease progression has fuelled a large number of studies, from its 3D structure to the characterization of specific cellular partners. However, no direct imaging and quantification of Vpr-Vpr interaction in living cells has yet been reported. To address this issue, eGFP- and mCherry proteins were tagged by Vpr, expressed in HeLa cells and their interaction was studied by two photon fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy. Results Results show that Vpr forms homo-oligomers at or close to the nuclear envelope. Moreover, Vpr dimers and trimers were found in the cytoplasm and in the nucleus. Point mutations in the three α helices of Vpr drastically impaired Vpr oligomerization and localization at the nuclear envelope while point mutations outside the helical regions had no effect. Theoretical structures of Vpr mutants reveal that mutations within the α-helices could perturb the leucine zipper like motifs. The ΔQ44 mutation has the most drastic effect since it likely disrupts the second helix. Finally, all Vpr point mutants caused cell apoptosis suggesting that Vpr-mediated apoptosis functions independently from Vpr oligomerization. Conclusion We report that Vpr oligomerization in HeLa cells relies on the hydrophobic core formed by the three α helices. This oligomerization is required for Vpr localization at the nuclear envelope but not for Vpr-mediated apoptosis.

  6. Second-harmonic generation and fluorescence lifetime imaging microscopy through a rodent mammary imaging window

    Science.gov (United States)

    Young, Pamela A.; Nazir, Muhammad; Szulczewski, Michael J.; Keely, Patricia J.; Eliceiri, Kevin W.

    2012-03-01

    Tumor-Associated Collagen Signatures (TACS) have been identified that manifest in specific ways during breast tumor progression and that correspond to patient outcome. There are also compelling metabolic changes associated with carcinoma invasion and progression. We have characterized the difference in the autofluorescent properties of metabolic co-factors, NADH and FAD, between normal and carcinoma breast cell lines. Also, we have shown in vitro that increased collagen density alters metabolic genes which are associated with glycolysis and leads to a more invasive phenotype. Establishing the relationship between collagen density, cellular metabolism, and metastasis in physiologically relevant cancer models is crucial for developing cancer therapies. To study cellular metabolism with respect to collagen density in vivo, we use multiphoton fluorescence excitation microscopy (MPM) in conjunction with a rodent mammary imaging window implanted in defined mouse cancer models. These models are ideal for the study of collagen changes in vivo, allowing determination of corresponding metabolic changes in breast cancer invasion and progression. To measure cellular metabolism, we collect fluorescence lifetime (FLIM) signatures of NADH and FAD, which are known to change based on the microenvironment of the cells. Additionally, MPM systems are capable of collecting second harmonic generation (SHG) signals which are a nonlinear optical property of collagen. Therefore, MPM, SHG, and FLIM are powerful tools with great potential for characterizing key features of breast carcinoma in vivo. Below we present the current efforts of our collaborative group to develop intravital approaches based on these imaging techniques to look at defined mouse mammary models.

  7. In vivo multiphoton and fluorescence lifetime imaging microscopy of the healthy and cholestatic liver

    Science.gov (United States)

    Kuznetsova, Daria S.; Dudenkova, Varvara V.; Rodimova, Svetlana A.; Bobrov, Nikolai V.; Zagainov, Vladimir E.; Zagaynova, Elena V.

    2018-02-01

    A cholestatic liver disease presents one of the most common liver diseases and can potentially progress to cirrhosis or even cholangiocarcinoma. Conventional techniques are insufficient to precisely describe the complex internal structure, heterogeneous cell populations and the dynamics of biological processes of the liver. Currently, the methods of multiphoton and fluorescence lifetime imaging microscopy are actively introducing to biomedical research. Those methods are extremely informative and non-destructive that allows studying of a large number of processes occurring inside cells and tissues, analyzing molecular cellular composition, as well as evaluating the state of connective tissue fibers due to their ability to generate a second optical harmonic. Multiphoton and FLIM microscopy do not need additional staining of samples or the incorporation of any markers to study metabolism, lipid composition, microstructure analysis, evaluation of fibrous structures. These parameters have pronounced changes in hepatocytes of liver with common pathological diseases. Thereby in this study we investigated metabolic changes in the healthy and cholestatic liver based on the fluorescence of the metabolic co-factors NAD(P)H and FAD by multiphoton microscopy combined with FLIM. To estimate the contribution of energy metabolism and lipogenesis in the observed changes of the metabolic profile, a separate analysis of NADH and NADPH was presented. The data can be used to develop new criteria for the identification of hepatic pathology at the level of hepatocyte changes directed to personalized medicine in the future.

  8. Two-photon excitation with pico-second fluorescence lifetime imaging to detect nuclear association of flavanols

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Harvey, Irene, E-mail: i.mueller-harvey@reading.ac.uk [Chemistry and Biochemistry Laboratory, Food Production and Quality Research Division, School of Agriculture, Policy and Development, University of Reading, P O Box 236, Reading RG6 6AT (United Kingdom); Feucht, Walter, E-mail: walter.feucht@gmail.com [Department of Plant Sciences, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Polster, Juergen, E-mail: j.polster@wzw.tum.de [Department of Physical Biochemistry, Technical University of Munich (TUM), Wissenschaftszentrum Weihenstephan (WZW), D-85354 Freising (Germany); Trnkova, Lucie, E-mail: lucie.trnkova@uhk.cz [University of Hradec Kralove, Faculty of Science, Department of Chemistry, Rokitanskeho 62, 50003 Hradec Kralove (Czech Republic); Burgos, Pierre, E-mail: pierre.burgos@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Parker, Anthony W., E-mail: tony.parker@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Botchway, Stanley W., E-mail: stan.botchway@stfc.ac.uk [Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

    2012-03-16

    Highlights: Black-Right-Pointing-Pointer This fluorescence lifetime imaging microscopy (FLIM) technique for flavanols overcomes autofluorescence interference in cells. Black-Right-Pointing-Pointer Plant flavanols differed in their lifetimes. Black-Right-Pointing-Pointer Dissolved and bound flavanols revealed contrasting lifetime changes. Black-Right-Pointing-Pointer This technique will allow studying of flavanol trafficking in live cells. - Abstract: Two-photon excitation enabled for the first time the observation and measurement of excited state fluorescence lifetimes from three flavanols in solution, which were {approx}1.0 ns for catechin and epicatechin, but <45 ps for epigallocatechin gallate (EGCG). The shorter lifetime for EGCG is in line with a lower fluorescence quantum yield of 0.003 compared to catechin (0.015) and epicatechin (0.018). In vivo experiments with onion cells demonstrated that tryptophan and quercetin, which tend to be major contributors of background fluorescence in plant cells, have sufficiently low cross sections for two-photon excitation at 630 nm and therefore do not interfere with detection of externally added or endogenous flavanols in Allium cepa or Taxus baccata cells. Applying two-photon excitation to flavanols enabled 3-D fluorescence lifetime imaging microscopy and showed that added EGCG penetrated the whole nucleus of onion cells. Interestingly, EGCG and catechin showed different lifetime behaviour when bound to the nucleus: EGCG lifetime increased from <45 to 200 ps, whilst catechin lifetime decreased from 1.0 ns to 500 ps. Semi-quantitative measurements revealed that the relative ratios of EGCG concentrations in nucleoli associated vesicles: nucleus: cytoplasm were ca. 100:10:1. Solution experiments with catechin, epicatechin and histone proteins provided preliminary evidence, via the appearance of a second lifetime ({tau}{sub 2} = 1.9-3.1 ns), that both flavanols may be interacting with histone proteins. We conclude that there

  9. Long-term fluorescence lifetime imaging of a genetically encoded sensor for caspase-3 activity in mouse tumor xenografts

    Science.gov (United States)

    Zherdeva, Victoria; Kazachkina, Natalia I.; Shcheslavskiy, Vladislav; Savitsky, Alexander P.

    2018-03-01

    Caspase-3 is known for its role in apoptosis and programmed cell death regulation. We detected caspase-3 activation in vivo in tumor xenografts via shift of mean fluorescence lifetimes of a caspase-3 sensor. We used the genetically encoded sensor TR23K based on the red fluorescent protein TagRFP and chromoprotein KFP linked by 23 amino acid residues (TagRFP-23-KFP) containing a specific caspase cleavage DEVD motif to monitor the activity of caspase-3 in tumor xenografts by means of fluorescence lifetime imaging-Forster resonance energy transfer. Apoptosis was induced by injection of paclitaxel for A549 lung adenocarcinoma and etoposide and cisplatin for HEp-2 pharynx adenocarcinoma. We observed a shift in lifetime distribution from 1.6 to 1.9 ns to 2.1 to 2.4 ns, which indicated the activation of caspase-3. Even within the same tumor, the lifetime varied presumably due to the tumor heterogeneity and the different depth of tumor invasion. Thus, processing time-resolved fluorescence images allows detection of both the cleaved and noncleaved states of the TR23K sensor in real-time mode during the course of several weeks noninvasively. This approach can be used in drug screening, facilitating the development of new anticancer agents as well as improvement of chemotherapy efficiency and its adaptation for personal treatment.

  10. Using non-empirically tuned range-separated functionals with simulated emission bands to model fluorescence lifetimes.

    Science.gov (United States)

    Wong, Z C; Fan, W Y; Chwee, T S; Sullivan, Michael B

    2017-08-09

    Fluorescence lifetimes were evaluated using TD-DFT under different approximations for the emitting molecule and various exchange-correlation functionals, such as B3LYP, BMK, CAM-B3LYP, LC-BLYP, M06, M06-2X, M11, PBE0, ωB97, ωB97X, LC-BLYP*, and ωB97X* where the range-separation parameters in the last two functionals were tuned in a non-empirical fashion. Changes in the optimised molecular geometries between the ground and electronically excited states were found to affect the quality of the calculated lifetimes significantly, while the inclusion of vibronic features led to further improvements over the assumption of a vertical electronic transition. The LC-BLYP* functional was found to return the most accurate fluorescence lifetimes with unsigned errors that are mostly within 1.5 ns of experimental values.

  11. FLIMX: A Software Package to Determine and Analyze the Fluorescence Lifetime in Time-Resolved Fluorescence Data from the Human Eye.

    Directory of Open Access Journals (Sweden)

    Matthias Klemm

    Full Text Available Fluorescence lifetime imaging ophthalmoscopy (FLIO is a new technique for measuring the in vivo autofluorescence intensity decays generated by endogenous fluorophores in the ocular fundus. Here, we present a software package called FLIM eXplorer (FLIMX for analyzing FLIO data. Specifically, we introduce a new adaptive binning approach as an optimal tradeoff between the spatial resolution and the number of photons required per pixel. We also expand existing decay models (multi-exponential, stretched exponential, spectral global analysis, incomplete decay to account for the layered structure of the eye and present a method to correct for the influence of the crystalline lens fluorescence on the retina fluorescence. Subsequently, the Holm-Bonferroni method is applied to FLIO measurements to allow for group comparisons between patients and controls on the basis of fluorescence lifetime parameters. The performance of the new approaches was evaluated in five experiments. Specifically, we evaluated static and adaptive binning in a diabetes mellitus patient, we compared the different decay models in a healthy volunteer and performed a group comparison between diabetes patients and controls. An overview of the visualization capabilities and a comparison of static and adaptive binning is shown for a patient with macular hole. FLIMX's applicability to fluorescence lifetime imaging microscopy is shown in the ganglion cell layer of a porcine retina sample, obtained by a laser scanning microscope using two-photon excitation.

  12. FLIMX: A Software Package to Determine and Analyze the Fluorescence Lifetime in Time-Resolved Fluorescence Data from the Human Eye.

    Science.gov (United States)

    Klemm, Matthias; Schweitzer, Dietrich; Peters, Sven; Sauer, Lydia; Hammer, Martin; Haueisen, Jens

    2015-01-01

    Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique for measuring the in vivo autofluorescence intensity decays generated by endogenous fluorophores in the ocular fundus. Here, we present a software package called FLIM eXplorer (FLIMX) for analyzing FLIO data. Specifically, we introduce a new adaptive binning approach as an optimal tradeoff between the spatial resolution and the number of photons required per pixel. We also expand existing decay models (multi-exponential, stretched exponential, spectral global analysis, incomplete decay) to account for the layered structure of the eye and present a method to correct for the influence of the crystalline lens fluorescence on the retina fluorescence. Subsequently, the Holm-Bonferroni method is applied to FLIO measurements to allow for group comparisons between patients and controls on the basis of fluorescence lifetime parameters. The performance of the new approaches was evaluated in five experiments. Specifically, we evaluated static and adaptive binning in a diabetes mellitus patient, we compared the different decay models in a healthy volunteer and performed a group comparison between diabetes patients and controls. An overview of the visualization capabilities and a comparison of static and adaptive binning is shown for a patient with macular hole. FLIMX's applicability to fluorescence lifetime imaging microscopy is shown in the ganglion cell layer of a porcine retina sample, obtained by a laser scanning microscope using two-photon excitation.

  13. Actin cytoskeleton-dependent Rab GTPase-regulated angiotensin type I receptor lysosomal degradation studied by fluorescence lifetime imaging microscopy

    Science.gov (United States)

    Li, Hewang; Yu, Peiying; Sun, Yuansheng; Felder, Robin A.; Periasamy, Ammasi; Jose, Pedro A.

    2010-09-01

    The dynamic regulation of the cellular trafficking of human angiotensin (Ang) type 1 receptor (AT1R) is not well understood. Therefore, we investigated the cellular trafficking of AT1R-enhanced green fluorescent protein (EGFP) (AT1R-EGFP) heterologously expressed in HEK293 cells by determining the change in donor lifetime (AT1R-EGFP) in the presence or absence of acceptor(s) using fluorescence lifetime imaging-fluorescence resonance energy transfer (FRET) microscopy. The average lifetime of AT1R-EGFP in our donor-alone samples was ~2.33 ns. The basal state lifetime was shortened slightly in the presence of Rab5 (2.01+/-0.10 ns) or Rab7 (2.11+/-0.11 ns) labeled with Alexa 555, as the acceptor fluorophore. A 5-min Ang II treatment markedly shortened the lifetime of AT1R-EGFP in the presence of Rab5-Alexa 555 (1.78+/-0.31 ns) but was affected minimally in the presence of Rab7-Alexa 555 (2.09+/-0.37 ns). A 30-min Ang II treatment further decreased the AT1R-EGFP lifetime in the presence of both Rab5- and Rab7-Alexa 555. Latrunculin A but not nocodazole pretreatment blocked the ability of Ang II to shorten the AT1R-EGFP lifetime. The occurrence of FRET between AT1R-EGFP (donor) and LAMP1-Alexa 555 (acceptor) with Ang II stimulation was impaired by photobleaching the acceptor. These studies demonstrate that Ang II-induced AT1R lysosomal degradation through its association with LAMP1 is regulated by Rab5/7 via mechanisms that are dependent on intact actin cytoskeletons.

  14. Characterization of standard reference material 2944, Bi-ion-doped glass, spectral correction standard for red fluorescence

    International Nuclear Information System (INIS)

    DeRose, Paul C.; Smith, Melody V.; Anderson, Jeffrey R.; Kramer, Gary W.

    2013-01-01

    Standard Reference Material (SRM) 2944 is a cuvette-shaped, Bi-ion-doped glass, recommended for optimal use for relative spectral correction of emission from 590 nm to 805 nm and day-to-day performance verification of steady-state fluorescence spectrometers. Properties of this standard that influence its effective use or contribute to the uncertainty in its certified emission spectrum were explored here. These properties include its photostability, absorbance, dissolution rate in water, anisotropy and temperature coefficient of fluorescence intensity. The expanded uncertainties (k=2) in the certified spectrum are about 4% around the nominal peak maximum at 704 nm and increase to about 6% at the wings, using an excitation wavelength of 515 nm. -- Highlights: ► The fluorescence emission spectrum of SRM 2944 was determined for spectral correction. ► This Bi-ion-doped glass has been certified in the fluorescence region from 530 nm to 830 nm. ► Fluorescence properties of the glass were determined, e.g., anisotropy, lifetime. ► SRM 2944 is photostable under common visible lamp excitation, when UV light is not present

  15. Study on the effect of deposition rate and concentration of Eu on the fluorescent lifetime of CsI: Tl thin film

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yijun; Guo, Lina [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, Chengdu 610054 (China); Liu, Shuang, E-mail: shuangliu@uestc.edu.cn [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, Chengdu 610054 (China); Wang, Qianfeng; Zhang, Shangjian; Liu, Yong [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, Chengdu 610054 (China); Zhong, Zhiyong [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, Chengdu 610054 (China)

    2017-06-21

    Although there are many new scintillators being developed recently, CsI: Tl is still very efficient among them. The fluorescent lifetime is a very important parameter of CsI: Tl thin film and two series of experiments have been conducted to learn about it. Our experiments, however, have demonstrated that the deposition rate and the codoping of Eu{sup 2+} will significantly influence its fluorescent lifetime. In order to increase the efficiency of the imaging system, we intend to obtain a higher fluorescent lifetime for CsI: Tl thin film by controlling these two conditions. - Highlights: • We used vacuum vapor deposition method to grow the high-quality thin films. • The relationship between the deposition rate and the fluorescent lifetime of CsI: Tl thin film was tested. • Concentration of Eu on fluorescent lifetime of the CsI: Tl thin film was studied.

  16. Automated detection of breast cancer in resected specimens with fluorescence lifetime imaging

    Science.gov (United States)

    Phipps, Jennifer E.; Gorpas, Dimitris; Unger, Jakob; Darrow, Morgan; Bold, Richard J.; Marcu, Laura

    2018-01-01

    Re-excision rates for breast cancer lumpectomy procedures are currently nearly 25% due to surgeons relying on inaccurate or incomplete methods of evaluating specimen margins. The objective of this study was to determine if cancer could be automatically detected in breast specimens from mastectomy and lumpectomy procedures by a classification algorithm that incorporated parameters derived from fluorescence lifetime imaging (FLIm). This study generated a database of co-registered histologic sections and FLIm data from breast cancer specimens (N  =  20) and a support vector machine (SVM) classification algorithm able to automatically detect cancerous, fibrous, and adipose breast tissue. Classification accuracies were greater than 97% for automated detection of cancerous, fibrous, and adipose tissue from breast cancer specimens. The classification worked equally well for specimens scanned by hand or with a mechanical stage, demonstrating that the system could be used during surgery or on excised specimens. The ability of this technique to simply discriminate between cancerous and normal breast tissue, in particular to distinguish fibrous breast tissue from tumor, which is notoriously challenging for optical techniques, leads to the conclusion that FLIm has great potential to assess breast cancer margins. Identification of positive margins before waiting for complete histologic analysis could significantly reduce breast cancer re-excision rates.

  17. From morphology to biochemical state - intravital multiphoton fluorescence lifetime imaging of inflamed human skin

    Science.gov (United States)

    Huck, Volker; Gorzelanny, Christian; Thomas, Kai; Getova, Valentina; Niemeyer, Verena; Zens, Katharina; Unnerstall, Tim R.; Feger, Julia S.; Fallah, Mohammad A.; Metze, Dieter; Ständer, Sonja; Luger, Thomas A.; Koenig, Karsten; Mess, Christian; Schneider, Stefan W.

    2016-03-01

    The application of multiphoton microscopy in the field of biomedical research and advanced diagnostics promises unique insights into the pathophysiology of inflammatory skin diseases. In the present study, we combined multiphoton-based intravital tomography (MPT) and fluorescence lifetime imaging (MPT-FLIM) within the scope of a clinical trial of atopic dermatitis with the aim of providing personalised data on the aetiopathology of inflammation in a non-invasive manner at patients’ bedsides. These ‘optical biopsies’ generated via MPT were morphologically analysed and aligned with classical skin histology. Because of its subcellular resolution, MPT provided evidence of a redistribution of mitochondria in keratinocytes, indicating an altered cellular metabolism. Two independent morphometric algorithms reliably showed an even distribution in healthy skin and a perinuclear accumulation in inflamed skin. Moreover, using MPT-FLIM, detection of the onset and progression of inflammatory processes could be achieved. In conclusion, the change in the distribution of mitochondria upon inflammation and the verification of an altered cellular metabolism facilitate a better understanding of inflammatory skin diseases and may permit early diagnosis and therapy.

  18. Characterization of a pulsed x-ray source for fluorescent lifetime measurements

    International Nuclear Information System (INIS)

    Blankespoor, S.C.; Derenzo, S.E.; Moses, W.W.; Rossington, C.S.; Ito, M.; Oba, K.

    1994-01-01

    To search for new, fast, inorganic scintillators, the authors have developed a bench-top pulsed x-ray source for determining fluorescent lifetimes and wavelengths of compounds in crystal or powdered form. This source uses a light-excited x-ray tube which produces x-rays when light from a laser diode strikes its photocathode. The x-ray tube has a tungsten anode, a beryllium exit window, a 30 kV maximum tube bias, and a 50 μA maximum average cathode current. The laser produces 3 x 10 7 photons at 650 nm per ∼100 ps pulse, with up to 10 7 pulses/sec. The time spread for the laser diode, x-ray tube, and a microchannel plate photomultiplier tube is less than 120 ps fwhm. The mean x-ray energy at tube biases of 20, 25, and 30 kV is 9.4, 10.3, and 11.1 keV, respectively. The authors measured 140, 230, and 330 x-ray photons per laser diode pulse per steradian, at tube biases of 20, 25, and 30 kV, respectively. Background x-rays due to dark current occur at a rate of 1 x 10 6 and 3 x 10 6 photons/sec/steradian at biases of 25 and 30 kV, respectively. Data characterizing the x-ray output with an aluminum filter in the x-ray beam are also presented

  19. Alterations in cerebral metabolism observed in living rodents using fluorescence lifetime microscopy of intrinsic NADH (Conference Presentation)

    Science.gov (United States)

    Yaseen, Mohammad A.; Sakadžić, Sava; Sutin, Jason; Wu, Weicheng; Fu, Buyin; Boas, David A.

    2017-02-01

    Monitoring cerebral energy metabolism at a cellular level is essential to improve our understanding of healthy brain function and its pathological alterations. In this study, we resolve specific alterations in cerebral metabolism utilizing minimally-invasive 2-Photon fluorescence lifetime imaging (2P-FLIM) measurements of reduced nicotinamide adenine dinucleotide (NADH) fluorescence, collected in vivo from anesthetized rats and mice. Time-resolved lifetime measurements enables distinction of different components contributing to NADH autofluorescence. These components reportedly represent different enzyme-bound formulations of NADH. Our observations from this study confirm the hypothesis that NADH FLIM can identify specific alterations in cerebral metabolism. Using time-correlated single photon counting (TCSPC) equipment and a custom-built multimodal imaging system, 2-photon fluorescence lifetime imaging (FLIM) was performed in cerebral tissue with high spatial and temporal resolution. Multi-exponential fits for NADH fluorescence lifetimes indicate 4 distinct components, or 'species.' We observed distinct variations in the relative proportions of these components before and after pharmacological-induced impairments to several reactions involved in anaerobic glycolysis and aerobic oxidative metabolism. Classification models developed with experimental data correctly predict the metabolic impairments associated with bicuculline-induced focal seizures in separate experiments. Compared to traditional intensity-based NADH measurements, lifetime imaging of NADH is less susceptible to the adverse effects of overlying blood vessels. Evaluating NADH measurements will ultimately lead to a deeper understanding of cerebral energetics and its pathology-related alterations. Such knowledge will likely aid development of therapeutic strategies for neurodegenerative diseases such as Alzheimer's Disease, Parkinson's disease, and stroke.

  20. CONSTRAINING THE LIFETIME AND OPENING ANGLE OF QUASARS USING FLUORESCENT Ly α EMISSION: THE CASE OF Q0420–388

    International Nuclear Information System (INIS)

    Borisova, Elena; Lilly, Simon J.; Cantalupo, Sebastiano; Prochaska, J. Xavier; Rakic, Olivera; Worseck, Gabor

    2016-01-01

    A toy model is developed to understand how the spatial distribution of fluorescent emitters in the vicinity of bright quasars could be affected by the geometry of the quasar bi-conical radiation field and by its lifetime. The model is then applied to the distribution of high-equivalent-width Ly α emitters (with rest-frame equivalent widths above 100 Å, threshold used in, e.g., Trainor and Steidel) identified in a deep narrow-band 36 × 36 arcmin 2 image centered on the luminous quasar Q0420–388. These emitters are found near the edge of the field and show some evidence of an azimuthal asymmetry on the sky of the type expected if the quasar is radiating in a bipolar cone. If these sources are being fluorescently illuminated by the quasar, the two most distant objects require a lifetime of at least 15 Myr for an opening angle of 60° or more, increasing to more than 40 Myr if the opening angle is reduced to a minimum of 30°. However, some other expected signatures of boosted fluorescence are not seen at the current survey limits, e.g., a fall off in Ly α brightness, or equivalent width, with distance. Furthermore, to have most of the Ly α emission of the two distant sources to be fluorescently boosted would require the quasar to have been significantly brighter in the past. This suggests that these particular sources may not be fluorescent, invalidating the above lifetime constraints. This would cast doubt on the use of this relatively low equivalent width threshold and thus also on the lifetime analysis in Trainor and Steidel.

  1. CONSTRAINING THE LIFETIME AND OPENING ANGLE OF QUASARS USING FLUORESCENT Ly α EMISSION: THE CASE OF Q0420–388

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Elena; Lilly, Simon J.; Cantalupo, Sebastiano [Institute for Astronomy, ETH Zurich, Zurich, CH-8093 (Switzerland); Prochaska, J. Xavier [UCO/Lick Observatory, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Rakic, Olivera; Worseck, Gabor, E-mail: borisova@phys.ethz.ch [Max-Planck-Institut für Astronomie, Heidelberg, D-69117 (Germany)

    2016-10-20

    A toy model is developed to understand how the spatial distribution of fluorescent emitters in the vicinity of bright quasars could be affected by the geometry of the quasar bi-conical radiation field and by its lifetime. The model is then applied to the distribution of high-equivalent-width Ly α emitters (with rest-frame equivalent widths above 100 Å, threshold used in, e.g., Trainor and Steidel) identified in a deep narrow-band 36 × 36 arcmin{sup 2} image centered on the luminous quasar Q0420–388. These emitters are found near the edge of the field and show some evidence of an azimuthal asymmetry on the sky of the type expected if the quasar is radiating in a bipolar cone. If these sources are being fluorescently illuminated by the quasar, the two most distant objects require a lifetime of at least 15 Myr for an opening angle of 60° or more, increasing to more than 40 Myr if the opening angle is reduced to a minimum of 30°. However, some other expected signatures of boosted fluorescence are not seen at the current survey limits, e.g., a fall off in Ly α brightness, or equivalent width, with distance. Furthermore, to have most of the Ly α emission of the two distant sources to be fluorescently boosted would require the quasar to have been significantly brighter in the past. This suggests that these particular sources may not be fluorescent, invalidating the above lifetime constraints. This would cast doubt on the use of this relatively low equivalent width threshold and thus also on the lifetime analysis in Trainor and Steidel.

  2. Fluorescence life-time imaging and steady state polarization for examining binding of fluorophores to gold nanoparticles.

    Science.gov (United States)

    Schwartz, Shmulik; Fixler, Dror; Popovtzer, Rachela; Shefi, Orit

    2015-11-01

    Nanocomposites as multifunctional agents are capable of combing imaging and cell biology technologies. The conventional methods used for validation of the conjugation process of nanoparticles (NPs) to fluorescent molecules such as spectroscopy analysis and surface potential measurements, are not sufficient. In this paper we present a new and highly sensitive procedure that uses the combination of (1) fluorescence spectrum, (2) fluorescence lifetime, and (3) steady state fluorescence polarization measurements. We characterize and analyze gold NPs with Lucifer yellow (LY) surface coating as a model. We demonstrate the ability to differentiate between LY-GNP (the conjugated complex) and a mixture of coated NP and free dyes. We suggest the approach for neuroscience applications where LY is used for detecting and labeling cells, studying morphology and intracellular communications. Histograms of Fluorescence lifetime imaging (FLIM) of free LY dye (Left) in comparison to the conjugated dye to gold nanoparticles, LY-GNP (Middle) enable the differentiation between LY-GNP (the conjugated complex) and a mixture of coated NP and free dyes (Right). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. From morphology to clinical pathophysiology: multiphoton fluorescence lifetime imaging at patients' bedside

    Science.gov (United States)

    Mess, Christian; Zens, Katharina; Gorzelanny, Christian; Metze, Dieter; Luger, Thomas A.; König, Karsten; Schneider, Stefan W.; Huck, Volker

    2017-02-01

    Application of multiphoton microscopy in the field of biomedical research and advanced diagnostics promises unique insights into the pathophysiology of skin diseases. By means of multiphoton excitation, endogenous biomolecules like NADH, collagen or elastin show autofluorescence or second harmonic generation. Thus, these molecules provide information about the subcellular morphology, epidermal architecture and physiological condition of the skin. To gain a deeper understanding of the linkage between cellular structure and physiological processes, non-invasive multiphotonbased intravital tomography (MPT) and fluorescence lifetime imaging (FLIM) were combined within the scopes of inflammatory skin, chronic wounds and drug delivery in clinical application. The optical biopsies generated via MPT were morphologically analyzed and aligned with classical skin histology. Because of its subcellular resolution, MPT provided evidence of a redistribution of mitochondria in keratinocytes, indicating an altered cellular metabolism. Independent morphometric algorithms reliably showed a perinuclear accumulation in lesional skin in contrast to an even distribution in healthy skin. Confirmatively, MPT-FLIM showed an obvious metabolic shift in lesions. Moreover, detection of the onset and progression of inflammatory processes could be achieved. The feasibility of primary in vivo tracking of applied therapeutic agents further broadened our scope: We examined the permeation and subsequent distribution of agents directly visualized in patientś skin in short-term repetitive measurements. Furthermore, we performed MPT-FLIM follow-up investigations in the long-term course of therapy. Therefore, clinical MPT-FLIM application offers new insights into the pathophysiology and the individual therapeutic course of skin diseases, facilitating a better understanding of the processes of inflammation and wound healing.

  4. Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging.

    Science.gov (United States)

    Nyström, Sofie; Bäck, Marcus; Nilsson, K Peter R; Hammarström, Per

    2017-10-20

    Proteins that deposit as amyloid in tissues throughout the body can be the cause or consequence of a large number of diseases. Among these we find neurodegenerative diseases such as Alzheimer's and Parkinson's disease afflicting primarily the central nervous system, and systemic amyloidosis where serum amyloid A, transthyretin and IgG light chains deposit as amyloid in liver, carpal tunnel, spleen, kidney, heart, and other peripheral tissues. Amyloid has been known and studied for more than a century, often using amyloid specific dyes such as Congo red and Thioflavin T (ThT) or Thioflavin (ThS). In this paper, we present heptamer-formyl thiophene acetic acid (hFTAA) as an example of recently developed complements to these dyes called luminescent conjugated oligothiophenes (LCOs). hFTAA is easy to use and is compatible with co-staining in immunofluorescence or with other cellular markers. Extensive research has proven that hFTAA detects a wider range of disease associated protein aggregates than conventional amyloid dyes. In addition, hFTAA can also be applied for optical assignment of distinct aggregated morphotypes to allow studies of amyloid fibril polymorphism. While the imaging methodology applied is optional, we here demonstrate hyperspectral imaging (HIS), laser scanning confocal microscopy and fluorescence lifetime imaging (FLIM). These examples show some of the imaging techniques where LCOs can be used as tools to gain more detailed knowledge of the formation and structural properties of amyloids. An important limitation to the technique is, as for all conventional optical microscopy techniques, the requirement for microscopic size of aggregates to allow detection. Furthermore, the aggregate should comprise a repetitive β-sheet structure to allow for hFTAA binding. Excessive fixation and/or epitope exposure that modify the aggregate structure or conformation can render poor hFTAA binding and hence pose limitations to accurate imaging.

  5. Magnetic field and temperature dependence of the fluorescence lifetime of Cr sup(3+) in GdA103

    International Nuclear Information System (INIS)

    Helman, J.S.; Caride, A.O.; Basso, H.C.; Terrile, M.C.; Carvalho, R.A.

    1991-01-01

    The fluorescence lifetime of Cr sup(3+) in GdA10 sub(3) was measured in the range 1.8 - 4.2 K in magnetic fields up to 6 T. The results show a remarkable dependence of the transition probabilities on magnetic order. A model based on the exchange interaction between Cr sup(3+) in highly excited states and the Gd sup(3+) ions is proposed. (author)

  6. Gentamicin differentially alters cellular metabolism of cochlear hair cells as revealed by NAD(P)H fluorescence lifetime imaging

    Science.gov (United States)

    Zholudeva, Lyandysha V.; Ward, Kristina G.; Nichols, Michael G.; Smith, Heather Jensen

    2015-05-01

    Aminoglycoside antibiotics are implicated as culprits of hearing loss in more than 120,000 individuals annually. Research has shown that the sensory cells, but not supporting cells, of the cochlea are readily damaged and/or lost after use of such antibiotics. High-frequency outer hair cells (OHCs) show a greater sensitivity to antibiotics than high- and low-frequency inner hair cells (IHCs). We hypothesize that variations in mitochondrial metabolism account for differences in susceptibility. Fluorescence lifetime microscopy was used to quantify changes in NAD(P)H in sensory and supporting cells from explanted murine cochleae exposed to mitochondrial uncouplers, inhibitors, and an ototoxic antibiotic, gentamicin (GM). Changes in metabolic state resulted in a redistribution of NAD(P)H between subcellular fluorescence lifetime pools. Supporting cells had a significantly longer lifetime than sensory cells. Pretreatment with GM increased NAD(P)H intensity in high-frequency sensory cells, as well as the NAD(P)H lifetime within IHCs. GM specifically increased NAD(P)H concentration in high-frequency OHCs, but not in IHCs or pillar cells. Variations in NAD(P)H intensity in response to mitochondrial toxins and GM were greatest in high-frequency OHCs. These results demonstrate that GM rapidly alters mitochondrial metabolism, differentially modulates cell metabolism, and provides evidence that GM-induced changes in metabolism are significant and greatest in high-frequency OHCs.

  7. 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.

  8. A high-throughput direct fluorescence resonance energy transfer-based assay for analyzing apoptotic proteases using flow cytometry and fluorescence lifetime measurements.

    Science.gov (United States)

    Suzuki, Miho; Sakata, Ichiro; Sakai, Takafumi; Tomioka, Hiroaki; Nishigaki, Koichi; Tramier, Marc; Coppey-Moisan, Maïté

    2015-12-15

    Cytometry is a versatile and powerful method applicable to different fields, particularly pharmacology and biomedical studies. Based on the data obtained, cytometric studies are classified into high-throughput (HTP) or high-content screening (HCS) groups. However, assays combining the advantages of both are required to facilitate research. In this study, we developed a high-throughput system to profile cellular populations in terms of time- or dose-dependent responses to apoptotic stimulations because apoptotic inducers are potent anticancer drugs. We previously established assay systems involving protease to monitor live cells for apoptosis using tunable fluorescence resonance energy transfer (FRET)-based bioprobes. These assays can be used for microscopic analyses or fluorescence-activated cell sorting. In this study, we developed FRET-based bioprobes to detect the activity of the apoptotic markers caspase-3 and caspase-9 via changes in bioprobe fluorescence lifetimes using a flow cytometer for direct estimation of FRET efficiencies. Different patterns of changes in the fluorescence lifetimes of these markers during apoptosis were observed, indicating a relationship between discrete steps in the apoptosis process. The findings demonstrate the feasibility of evaluating collective cellular dynamics during apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. DNA origami-based standards for quantitative fluorescence microscopy.

    Science.gov (United States)

    Schmied, Jürgen J; Raab, Mario; Forthmann, Carsten; Pibiri, Enrico; Wünsch, Bettina; Dammeyer, Thorben; Tinnefeld, Philip

    2014-01-01

    Validating and testing a fluorescence microscope or a microscopy method requires defined samples that can be used as standards. DNA origami is a new tool that provides a framework to place defined numbers of small molecules such as fluorescent dyes or proteins in a programmed geometry with nanometer precision. The flexibility and versatility in the design of DNA origami microscopy standards makes them ideally suited for the broad variety of emerging super-resolution microscopy methods. As DNA origami structures are durable and portable, they can become a universally available specimen to check the everyday functionality of a microscope. The standards are immobilized on a glass slide, and they can be imaged without further preparation and can be stored for up to 6 months. We describe a detailed protocol for the design, production and use of DNA origami microscopy standards, and we introduce a DNA origami rectangle, bundles and a nanopillar as fluorescent nanoscopic rulers. The protocol provides procedures for the design and realization of fluorescent marks on DNA origami structures, their production and purification, quality control, handling, immobilization, measurement and data analysis. The procedure can be completed in 1-2 d.

  10. Effect of calcinations temperature on the luminescence intensity and fluorescent lifetime of Tb3+-doped hydroxyapatite (Tb-HA nanocrystallines

    Directory of Open Access Journals (Sweden)

    Hairong Yin

    2017-06-01

    Full Text Available Hydroxyapatite luminescent nanocrystallines doped with 6 mol.% Tb3+ (Tb-HA were prepared via chemical deposition method and calcined at different temperature, and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied. TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature; while the particles sizes decreased from 190 nm to 110 nm. The crystallinity degree increased. The typical emission peaks attributed to Tb3+ ions were observed in emission spectra of 6 mol.% Tb-HA under 378 nm excitation. The luminescent intensity of Tb-HA, which showed the fluorescence quenching, firstly enhanced and then decreased at 700 °C; while the fluorescent lifetime increased firstly and then decreased after 600 °C. Furthermore, the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition (IR: IO increases firstly and then decreases, which revealed that the proportion of substitute type and site of Ca2+ ions by Tb3+ ions were helpful to realize the substitute process and functional structure design.

  11. Segmented frequency-domain fluorescence lifetime measurements: minimizing the effects of photobleaching within a multi-component system.

    Science.gov (United States)

    Marwani, Hadi M; Lowry, Mark; Keating, Patrick; Warner, Isiah M; Cook, Robert L

    2007-11-01

    This study introduces a newly developed frequency segmentation and recombination method for frequency-domain fluorescence lifetime measurements to address the effects of changing fractional contributions over time and minimize the effects of photobleaching within multi-component systems. Frequency segmentation and recombination experiments were evaluated using a two component system consisting of fluorescein and rhodamine B. Comparison of experimental data collected in traditional and segmented fashion with simulated data, generated using different changing fractional contributions, demonstrated the validity of the technique. Frequency segmentation and recombination was also applied to a more complex system consisting of pyrene with Suwannee River fulvic acid reference and was shown to improve recovered lifetimes and fractional intensity contributions. It was observed that photobleaching in both systems led to errors in recovered lifetimes which can complicate the interpretation of lifetime results. Results showed clear evidence that the frequency segmentation and recombination method reduced errors resulting from a changing fractional contribution in a multi-component system, and allowed photobleaching issues to be addressed by commercially available instrumentation.

  12. The fluorescence lifetime of BRI1-GFP as probe for the noninvasive determination of the membrane potential in living cells

    Science.gov (United States)

    Elgass, K.; Caesar, K.; Schleifenbaum, F.; Meixner, A. J.; Harter, K.

    2010-02-01

    As the excited state lifetime of a fluorescent molecule depends on its environment, it is possible to use it as a probe for physico-chemical parameters of the surrounding medium. Whereas this is well known for many solid guest/host systems, only few reports of quantitative, temporal resolved in vivo studies to monitor the nano-environment for a protein-coupled chromophore such as GFP are known from literature. Here we present a novel approach to determine the membrane potential of living (plant) cells based on the fluorescence lifetime (FLT) analysis of membrane-located GFP. By using confocal sample scanning microscopy (CSSM) combined with fluorescence lifetime imaging microscopy, we recently showed that the phytohormone brassinolide (BL) induces cell wall expansion and a decrease in the FLT of the BRI1-GFP in living cells of Arabidopsis thaliana seedlings. BRI1 is the dominant functional receptor for BL in Arabidopsis and locates to the plasma membrane. Although the dependence of the FLT of GFP on its physico-chemical environment such as pH-value, refractive index and pressure has been reported, the observed FLT decrease of BRI1-GFP in response to BL application could not be explained by these parameters. However, our in vivo FLT and CSSM analyses indicate that the BLinduced change in the FLT of BRI1-GFP is caused by hyperpolarisation of the plasma membrane (Em). Thus, our results indicate that BRI1-GFP serves as sensitive and non-invasive probe for recording the Em of the plasma membrane in living plant cells with high spatio-temporal resolution.

  13. 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

  14. Mercury effects on Thalassiosira weissflogii: Applications of two-photon excitation chlorophyll fluorescence lifetime imaging and flow cytometry

    International Nuclear Information System (INIS)

    Wu Yun; Zeng Yan; Qu, Jianan Y.; Wang Wenxiong

    2012-01-01

    The toxic effects of inorganic mercury [Hg(II)] and methylmercury (MeHg) on the photosynthesis and population growth in a marine diatom Thalassiosira weissflogii were investigated using two methods: two-photon excitation fluorescence lifetime imaging (FLIM) and flow cytometry (FCM). For photosynthesis, Hg(II) exposure increased the average chlorophyll fluorescence lifetime, whereas such increment was not found under MeHg stress. This may be caused by the inhibitory effect of Hg(II) instead of MeHg on the electron transport chain. For population growth, modeled specific growth rate data showed that the reduction in population growth by Hg(II) mainly resulted from an increased number of injured cells, while the live cells divided at the normal rates. However, MeHg inhibitory effects on population growth were contributed by the reduced division rates of all cells. Furthermore, the cell images and the FCM data reflected the morphological changes of diatom cells under Hg(II)/MeHg exposure vividly and quantitatively. Our results demonstrated that the toxigenicity mechanisms between Hg(II) and MeHg were different in the algal cells.

  15. Fluorescence lifetime studies of MeV erbium implanted silica glass

    International Nuclear Information System (INIS)

    Lidgard, A.; Polman, A.; Jacobsen, D.C.; Blonder, G.E.; Kistler, R.; Poate, J.M.; Becker, P.C.

    1991-01-01

    MeV erbium ion implantation into various SiO 2 glasses has been studied with the aim of incorporating the rare-earth dopant as an optically active ion in the silica network. The lifetime of the excited state ranges from 1.6 to 12.8 ms, depending on base material and implantation fluence. These results have positive implications for silica-based integrated optical technology. (Author)

  16. Fluorescence lifetime studies of MeV erbium implanted silica glass

    Energy Technology Data Exchange (ETDEWEB)

    Lidgard, A.; Polman, A.; Jacobsen, D.C.; Blonder, G.E.; Kistler, R.; Poate, J.M.; Becker, P.C. (AT and T Bell Labs., Murray Hill, NJ (USA))

    1991-05-23

    MeV erbium ion implantation into various SiO{sub 2} glasses has been studied with the aim of incorporating the rare-earth dopant as an optically active ion in the silica network. The lifetime of the excited state ranges from 1.6 to 12.8 ms, depending on base material and implantation fluence. These results have positive implications for silica-based integrated optical technology. (Author).

  17. Atmospheric Muon Lifetime, Standard Model of Particles and the Lead Stopping Power for Muons

    Science.gov (United States)

    Gutarra-Leon, Angel; Barazandeh, Cioli; Majewski, Walerian

    2017-01-01

    The muon is a fundamental particles of matter. It decays into three other leptons through an exchange of the weak vector bosons W +/W-. Muons are present in the atmosphere from cosmic ray showers. By detecting the time delay between arrival of the muon and an appearance of the decay electron in our detector, we'll measure muon's lifetime at rest. From the lifetime we should be able to find the ratio gw /MW of the weak coupling constant gw (a weak analog of the electric charge) to the mass of the W-boson MW. Vacuum expectation value v of the Higg's field, which determines the masses of all particles of the Standard Model (SM), could be then calculated from our muon experiment as v =2MWc2/gw =(τ m μc2/6 π3ĥ)1/4m μc2 in terms of muon mass mµand muon lifetime τ only. Using known experimental value for MWc2 = 80.4 GeV we'll find the weak coupling constant gw. Using the SM relation e =gwsin θ√ hc ɛ0 with the experimental value of the Z0-photon weak mixing angle θ = 29o we could find from our muon lifetime the value of the elementary electric charge e. We'll determine the sea-level fluxes of low-energy and high-energy cosmic muons, then we'll shield the detector with varying thicknesses of lead plates and find the energy-dependent muon stopping power in lead.

  18. A fusion-spliced near-field optical fiber probe using photonic crystal fiber for nanoscale thermometry based on fluorescence-lifetime measurement of quantum dots.

    Science.gov (United States)

    Fujii, Takuro; Taguchi, Yoshihiro; Saiki, Toshiharu; Nagasaka, Yuji

    2011-01-01

    We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called fluorescence near-field optics thermal nanoscopy (Fluor-NOTN). Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se quantum dots (QDs). For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF) and a conventional single-mode fiber (SMF). The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

  19. The increase of NADH fluorescence lifetime is associated with the metabolic change during osteogenic differentiation of human mesenchymal stem cells (hMSCs)

    Science.gov (United States)

    Guo, Han Wen; Yu, Jia Sin; Hsu, Shu Han; Wei, Yau Huei; Lee, Oscar K.; Wang, Hsing Wen

    2011-03-01

    Fluorescence lifetime of NADH had been used as an optical marker for monitoring cellular metabolism. In our pervious studies, we have demonstrated that NADH lifetime of hMSCs increase gradually with time of osteogenic differentiation. In this study, we measured NADH lifetime of hMSCs from a different donor as well as the corresponding metabolic indices such as ATP level, oxygen consumption and lactate release. We also measure the quantity of Complex I, III, IV and V. The results show that during differentiation more oxygen consumed, higher ATP level expressed and less lactate released, and the increase of NADH lifetime was associated with ATP level. Higher expression of the total Complex protein was observed at 3 and 4 weeks after differentiation than controls. However, Complex I expression did not show significant correlation with the increase of NADH fluorescence lifetime. In summary, we demonstrated that the change of NADH lifetime was associated with the metabolic change during osteogenic differentiation of hMSCs. The increase of NADH lifetime was in part due to the increased Complex protein interaction in mitochondria after differentiation.

  20. Gating circuit for single photon-counting fluorescence lifetime instruments using high repetition pulsed light sources

    International Nuclear Information System (INIS)

    Laws, W.R.; Potter, D.W.; Sutherland, J.C.

    1984-01-01

    We have constructed a circuit that permits conventional timing electronics to be used in single photon-counting fluorimeters with high repetition rate excitation sources (synchrotrons and mode-locked lasers). Most commercial time-to-amplitude and time-to-digital converters introduce errors when processing very short time intervals and when subjected to high-frequency signals. This circuit reduces the frequency of signals representing the pulsed light source (stops) to the rate of detected fluorescence events (starts). Precise timing between the start/stop pair is accomplished by using the second stop pulse after a start pulse. Important features of our design are that the circuit is insensitive to the simultaneous occurrence of start and stop signals and that the reduction in the stop frequency allows the start/stop time interval to be placed in linear regions of the response functions of commercial timing electronics

  1. Probing the photoluminescence properties of gold nanoclusters by fluorescence lifetime correlation spectroscopy

    International Nuclear Information System (INIS)

    Yuan, C. T.; Lin, T. N.; Shen, J. L.; Lin, C. A.; Chang, W. H.; Cheng, H. W.; Tang, J.

    2013-01-01

    Gold nanoclusters (Au NCs) have attracted much attention for promising applications in biological imaging owing to their tiny sizes and biocompatibility. So far, most efforts have been focused on the strategies for fabricating high-quality Au NCs and then characterized by conventional ensemble measurement. Here, a fusion single-molecule technique combining fluorescence correlation spectroscopy and time-correlated single-photon counting can be successfully applied to probe the photoluminescence (PL) properties for sparse Au NCs. In this case, the triplet-state dynamics and diffusion process can be observed simultaneously and the relevant time constants can be derived. This work provides a complementary insight into the PL mechanism at the molecular levels for Au NCs in solution

  2. Fluorescence lifetime imaging ophthalmoscopy in type 2 diabetic patients who have no signs of diabetic retinopathy

    Science.gov (United States)

    Schweitzer, Dietrich; Deutsch, Lydia; Klemm, Matthias; Jentsch, Susanne; Hammer, Martin; Peters, Sven; Haueisen, Jens; Müller, Ulrich A.; Dawczynski, Jens

    2015-06-01

    The time-resolved autofluorescence of the eye is used for the detection of metabolic alteration in diabetic patients who have no signs of diabetic retinopathy. One eye from 37 phakic and 11 pseudophakic patients with type 2 diabetes, and one eye from 25 phakic and 23 pseudophakic healthy subjects were included in the study. After a three-exponential fit of the decay of autofluorescence, histograms of lifetimes τi, amplitudes αi, and relative contributions Qi were statistically compared between corresponding groups in two spectral channels (490diabetic patients and age-matched controls (p450 ps, and the shift of τ3 from ˜3000 to 3700 ps in ch1 of diabetic patients when compared with healthy subjects indicate an increased production of free flavin adenine dinucleotide, accumulation of advanced glycation end products (AGE), and, probably, a change from free to protein-bound reduced nicotinamide adenine dinucleotide at the fundus. AGE also accumulated in the crystalline lens.

  3. Comparitive study of fluorescence lifetime quenching of rhodamine 6G by MoS2 and Au-MoS2

    Science.gov (United States)

    Shakya, Jyoti; Kasana, Parath; Mohanty, T.

    2018-04-01

    Time resolved fluorescence study of Rhodamine 6G (R6G) in the presence of Molybdenum disulfide (MoS2) nanosheets and gold doped MoS2 (Au-MoS2) have been carried out and discussed. We have analyzed the fluorescence decay curves of R6G and it is observed that Au-MoS2 is a better fluorescence lifetime quencher as compare to MoS2 nanosheets. Also, the energy transfer efficiency and energy transfer rate from R6G to MoS2 and Au-MoS2 has been calculated and found higher for Au-MoS2.

  4. Preparation and properties of Nd{sup 3+}:SrAlF{sub 5} nanocrystals embedded fluorophosphate transparent glass-ceramic with long fluorescence lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Ruilin; Wang, Jinlong; Zhang, Liaolin; Liu, Chunxiao; Wei, Wei [Nanjing University of Posts and Telecommunications, School of Optoelectronic Engineering, Nanjing (China)

    2016-07-15

    Nd{sup 3+}:SrAlF{sub 5} nanocrystals embedded fluorophosphate glass-ceramics were prepared by the melt quenching and subsequent thermal treatment method. The formation of SrAlF{sub 5} nanocrystals in the glass was confirmed by X-ray diffraction and scanning electron microscope. The fluorescence intensity and lifetime of the glass-ceramics increased with the increase of size of nanocrystals. Importantly, by controlling growth of nanocrystals, an obvious enhancement of lifetime (725 μs) emerged in the glass-ceramics heat-treated at 510 C and the transmittance can reach to 72.2 % at 1049 nm. The enhanced fluorescence intensity and lifetime were ascribed to the comfortable local environment to the Nd{sup 3+} ion and scattering of the nanoparticle embedded into the glass matrix. (orig.)

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

    Science.gov (United States)

    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

  6. Fluorescence lifetime measurements to determine the core-shell nanostructure of FITC-doped silica nanoparticles: An optical approach to evaluate nanoparticle photostability

    International Nuclear Information System (INIS)

    Santra, Swadeshmukul; Liesenfeld, Bernd; Bertolino, Chiara; Dutta, Debamitra; Cao Zehui; Tan Weihong; Moudgil, Brij M.; Mericle, Robert A.

    2006-01-01

    In this paper, we described a novel fluorescence lifetime-based approach to determine the core-shell nanostructure of FITC-(fluorescein isothiocyanate, isomer I) doped fluorescent silica nanoparticles (FSNPs). Because of phase homogeneity between the core and the shell, electron microscopic technique could not be used to characterize such core-shell nanostructure. Our optical approach not only revealed the core-shell nanostructure of FSNPs but also evaluated photobleaching of FSNPs both in the solvated and non-solvated (dry) states. The FSNPs were produced via Stoeber's method by hydrolysis and co-condensation reaction of tetraethylorthosilicate (TEOS) and fluorescein linked (3-aminopropyl)triethoxysilane (FITC-APTS conjugate) in the presence of ammonium hydroxide catalyst. To obtain a pure silica surface coating, FSNPs were then post-coated with TEOS. The average particle size was 135 nm as determined by TEM (transmission electron microscope) measurements. Fluorescence excitation and emission spectral data demonstrated successful doping of FITC dye molecules in FSNPs. Fluorescence lifetime data revealed that approximately 62% of dye molecules remained in the solvated silica shell, while 38% of dye molecules remained in the non-solvated (dry) silica core. Photobleaching experiments of FSNPs were conducted both in DI water (solution state) and in air (dry state). Severe photobleaching of FSNPs was observed in air. However, FSNPs were moderately photostable in the solution state. Photostability of FSNPs in both solution and dry states was explained on the basis of fluorescence lifetime data

  7. Automatic Segmentation of Fluorescence Lifetime Microscopy Images of Cells Using Multi-Resolution Community Detection -A First Study

    Science.gov (United States)

    Hu, Dandan; Sarder, Pinaki; Ronhovde, Peter; Orthaus, Sandra; Achilefu, Samuel; Nussinov, Zohar

    2014-01-01

    Inspired by a multi-resolution community detection (MCD) based network segmentation method, we suggest an automatic method for segmenting fluorescence lifetime (FLT) imaging microscopy (FLIM) images of cells in a first pilot investigation on two selected images. The image processing problem is framed as identifying segments with respective average FLTs against the background in FLIM images. The proposed method segments a FLIM image for a given resolution of the network defined using image pixels as the nodes and similarity between the FLTs of the pixels as the edges. In the resulting segmentation, low network resolution leads to larger segments, and high network resolution leads to smaller segments. Further, using the proposed method, the mean-square error (MSE) in estimating the FLT segments in a FLIM image was found to consistently decrease with increasing resolution of the corresponding network. The MCD method appeared to perform better than a popular spectral clustering based method in performing FLIM image segmentation. At high resolution, the spectral segmentation method introduced noisy segments in its output, and it was unable to achieve a consistent decrease in MSE with increasing resolution. PMID:24251410

  8. Automatic segmentation of fluorescence lifetime microscopy images of cells using multiresolution community detection--a first study.

    Science.gov (United States)

    Hu, D; Sarder, P; Ronhovde, P; Orthaus, S; Achilefu, S; Nussinov, Z

    2014-01-01

    Inspired by a multiresolution community detection based network segmentation method, we suggest an automatic method for segmenting fluorescence lifetime (FLT) imaging microscopy (FLIM) images of cells in a first pilot investigation on two selected images. The image processing problem is framed as identifying segments with respective average FLTs against the background in FLIM images. The proposed method segments a FLIM image for a given resolution of the network defined using image pixels as the nodes and similarity between the FLTs of the pixels as the edges. In the resulting segmentation, low network resolution leads to larger segments, and high network resolution leads to smaller segments. Furthermore, using the proposed method, the mean-square error in estimating the FLT segments in a FLIM image was found to consistently decrease with increasing resolution of the corresponding network. The multiresolution community detection method appeared to perform better than a popular spectral clustering-based method in performing FLIM image segmentation. At high resolution, the spectral segmentation method introduced noisy segments in its output, and it was unable to achieve a consistent decrease in mean-square error with increasing resolution. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

  9. In vivo detection of oral epithelial cancer using endogenous fluorescence lifetime imaging: a pilot human study (Conference Presentation)

    Science.gov (United States)

    Jo, Javier A.; Hwang, Dae Yon; Palma, Jorge; Cheng, Shuna; Cuenca, Rodrigo; Malik, Bilal; Jabbour, Joey; Cheng, Lisa; Wright, John; Maitland, Kristen

    2016-03-01

    Endogenous fluorescence lifetime imaging (FLIM) provides direct access to the concomitant functional and biochemical changes accompanying tissue transition from benign to precancerous and cancerous. Since FLIM can noninvasively measure different and complementary biomarkers of precancer and cancer, we hypothesize that it will aid in clinically detecting early oral epithelial cancer. Our group has recently demonstrated the detection of benign from premalignant and malignant lesions based on endogenous multispectral FLIM in the hamster cheek-pouch model. Encouraged by these positive preliminary results, we have developed a handheld endoscope capable of acquiring multispectral FLIM images in real time from the oral mucosa. This novel FLIM endoscope is being used for imaging clinically suspicious pre-malignant and malignant lesions from patients before undergoing tissue biopsy for histopathological diagnosis of oral epithelial cancer. Our preliminary results thus far are already suggesting the potential of endogenous FLIM for distinguishing a variety of benign lesions from advanced dysplasia and squamous cell carcinoma (SCC). To the best of out knowledge, this is the first in vivo human study aiming to demonstrate the ability to predict the true malignancy of clinically suspicious lesions using endogenous FLIM. If successful, the resulting clinical tool will allow noninvasive real-time detection of epithelial precancerous and cancerous lesions in the oral mucosa and could potentially be used to assist at every step involved on the clinical management of oral cancer patients, from early screening and diagnosis, to treatment and monitoring of recurrence.

  10. The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex.

    Science.gov (United States)

    Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

    2016-02-05

    Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex

    Science.gov (United States)

    Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

    2016-02-01

    Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases.

  12. Selective plane illumination microscopy (SPIM) with time-domain fluorescence lifetime imaging microscopy (FLIM) for volumetric measurement of cleared mouse brain samples

    Science.gov (United States)

    Funane, Tsukasa; Hou, Steven S.; Zoltowska, Katarzyna Marta; van Veluw, Susanne J.; Berezovska, Oksana; Kumar, Anand T. N.; Bacskai, Brian J.

    2018-05-01

    We have developed an imaging technique which combines selective plane illumination microscopy with time-domain fluorescence lifetime imaging microscopy (SPIM-FLIM) for three-dimensional volumetric imaging of cleared mouse brains with micro- to mesoscopic resolution. The main features of the microscope include a wavelength-adjustable pulsed laser source (Ti:sapphire) (near-infrared) laser, a BiBO frequency-doubling photonic crystal, a liquid chamber, an electrically focus-tunable lens, a cuvette based sample holder, and an air (dry) objective lens. The performance of the system was evaluated with a lifetime reference dye and micro-bead phantom measurements. Intensity and lifetime maps of three-dimensional human embryonic kidney (HEK) cell culture samples and cleared mouse brain samples expressing green fluorescent protein (GFP) (donor only) and green and red fluorescent protein [positive Förster (fluorescence) resonance energy transfer] were acquired. The results show that the SPIM-FLIM system can be used for sample sizes ranging from single cells to whole mouse organs and can serve as a powerful tool for medical and biological research.

  13. 76 FR 70547 - Energy Conservation Program: Energy Conservation Standards for Fluorescent Lamp Ballasts

    Science.gov (United States)

    2011-11-14

    ... the term ``fluorescent lamp,'' which EPCA defines as ``a low pressure mercury electric-discharge... discharge into light,'' and as including the four enumerated types of fluorescent lamps for which EPCA... Conservation Program: Energy Conservation Standards for Fluorescent Lamp Ballasts; Final Rule #0;#0;Federal...

  14. Fluorescence lifetime spectroscopy: potential for in-vivo estimation of skin fluorophores changes after low power laser treatment

    Science.gov (United States)

    Ferulova, Inesa; Lihachev, Alexey; Spigulis, Janis

    2013-11-01

    The impact of visible cwlaser irradiation on skin autofluorescence lifetimes was investigated in spectral range from 450 nm to 600 nm. Skin optical provocations were performed during 1 min by 405 nm low power cw laser with power density up to 20 mW/cm2. Autofluorescence lifetimes were measured before and immediately after the optical provocation.

  15. Connoted hazard and perceived importance of fluorescent, neon, and standard safety colors.

    Science.gov (United States)

    Zielinska, O A; Mayhorn, C B; Wogalter, M S

    2017-11-01

    The perceived hazard and rated importance of standard safety, fluorescent, and neon colors are investigated. Colors are used in warnings to enhance hazard communication. Red has consistently been rated as the highest in perceived hazard. Orange, yellow, and black are the next highest in connoted hazard; however, there is discrepancy in their ordering. Safety standards, such as ANSI Z535.1, also list colors to convey important information, but little research has examined the perceived importance of colors. In addition to standard safety colors, fluorescent colors are more commonly used in warnings. Understanding hazard and importance perceptions of standard safety and fluorescent colors is necessary to create effective warnings. Ninety participants rated and ranked a total of 33 colors on both perceived hazard and perceived importance. Rated highest were the safety red colors from the American National Standard Institute (ANSI), International Organization for Standardization (ISO), and Federal Highway Administration (FHWA) together with three fluorescent colors (orange, yellow, and yellow-green) from 3 M on both dimensions. Rankings were similar to ratings except that fluorescent orange was the highest on perceived hazard, while fluorescent orange and safety red from the ANSI were ranked as the highest in perceived importance. Fluorescent colors convey hazard and importance levels as high as the standard safety red colors. Implications for conveying hazard and importance in warnings through color are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. A light diet for a giant appetite: An assessment of China's fluorescent lamp standard

    International Nuclear Information System (INIS)

    Lin Jiang

    2005-01-01

    Lighting has been one of the fastest growing electric end uses in China over the last 20 years, with an average annual growth rate of 14%. Fluorescent lighting provides a significant portion of China's lighting needs. In 1998, China produced 680 million fluorescent lamps, of which 420 million were linear fluorescent lamps of various diameters (T8-T12). There are substantial variations both in energy efficiency and lighting performance among locally produced fluorescent lamps. Such variations present a perfect opportunity for policy intervention through energy efficiency standards to promote the adoption of more efficient fluorescent lamps in China. This paper analyzes China's 2003 minimum efficiency standard for linear fluorescent lamps and presents an assessment of its likely impacts on China's lighting energy consumption and greenhouse gas emissions

  17. Laser induced fluorescence lifetime characterization of Bacillus endospore species using time correlated single photon counting analysis with the multi-exponential fit method

    Science.gov (United States)

    Smith, Clint; Edwards, Jarrod; Fisher, Andmorgan

    2010-04-01

    Rapid detection of biological material is critical for determining presence/absence of bacterial endospores within various investigative programs. Even more critical is that if select material tests positive for bacillus endospores then tests should provide data at the species level. Optical detection of microbial endospore formers such as Bacillus sp. can be heavy, cumbersome, and may only identify at the genus level. Data provided from this study will aid in characterization needed by future detection systems for further rapid breakdown analysis to gain insight into a more positive signature collection of Bacillus sp. Literature has shown that fluorescence spectroscopy of endospores could be statistically separated from other vegetative genera, but could not be separated among one another. Results of this study showed endospore species separation is possible using laser-induce fluorescence with lifetime decay analysis for Bacillus endospores. Lifetime decays of B. subtilis, B. megaterium, B. coagulans, and B. anthracis Sterne strain were investigated. Using the Multi-Exponential fit method data showed three distinct lifetimes for each species within the following ranges, 0.2-1.3 ns; 2.5-7.0 ns; 7.5-15.0 ns, when laser induced at 307 nm. The four endospore species were individually separated using principle component analysis (95% CI).

  18. Non-Euclidean phasor analysis for quantification of oxidative stress in ex vivo human skin exposed to sun filters using fluorescence lifetime imaging microscopy

    Science.gov (United States)

    Osseiran, Sam; Roider, Elisabeth M.; Wang, Hequn; Suita, Yusuke; Murphy, Michael; Fisher, David E.; Evans, Conor L.

    2017-12-01

    Chemical sun filters are commonly used as active ingredients in sunscreens due to their efficient absorption of ultraviolet (UV) radiation. Yet, it is known that these compounds can photochemically react with UV light and generate reactive oxygen species and oxidative stress in vitro, though this has yet to be validated in vivo. One label-free approach to probe oxidative stress is to measure and compare the relative endogenous fluorescence generated by cellular coenzymes nicotinamide adenine dinucleotides and flavin adenine dinucleotides. However, chemical sun filters are fluorescent, with emissive properties that contaminate endogenous fluorescent signals. To accurately distinguish the source of fluorescence in ex vivo skin samples treated with chemical sun filters, fluorescence lifetime imaging microscopy data were processed on a pixel-by-pixel basis using a non-Euclidean separation algorithm based on Mahalanobis distance and validated on simulated data. Applying this method, ex vivo samples exhibited a small oxidative shift when exposed to sun filters alone, though this shift was much smaller than that imparted by UV irradiation. Given the need for investigative tools to further study the clinical impact of chemical sun filters in patients, the reported methodology may be applied to visualize chemical sun filters and measure oxidative stress in patients' skin.

  19. Quantitative time domain analysis of lifetime-based Förster resonant energy transfer measurements with fluorescent proteins: Static random isotropic fluorophore orientation distributions

    DEFF Research Database (Denmark)

    Alexandrov, Yuriy; Nikolic, Dino Solar; Dunsby, Christopher

    2018-01-01

    Förster resonant energy transfer (FRET) measurements are widely used to obtain information about molecular interactions and conformations through the dependence of FRET efficiency on the proximity of donor and acceptor fluorophores. Fluorescence lifetime measurements can provide quantitative...... into new software for fitting donor emission decay profiles. Calculated FRET parameters, including molar population fractions, are compared for the analysis of simulated and experimental FRET data under the assumption of static and dynamic fluorophores and the intermediate regimes between fully dynamic...... analysis of FRET efficiency and interacting population fraction. Many FRET experiments exploit the highly specific labelling of genetically expressed fluorescent proteins, applicable in live cells and organisms. Unfortunately, the typical assumption of fast randomization of fluorophore orientations...

  20. Study of lifetimes of fluorescence levels of tetravalent uranium in the incommensurate phase of thorium tetrabromide and tetrachloride

    International Nuclear Information System (INIS)

    Milicic, A.

    1989-01-01

    The lifetimes of radiative levels of tetravalent uranium in the incommensurate phase of thorium tetrahalides have been measured as a function of different parameters: site symmetry, temperature and concentration. The incommensurate phase of thorium tetrabromide and tetrachloride is characterized by a continuous distribution of site symmetries induced by a continuous and weak displacement of the halides around the thorium (uranium) ions. At low temperature, 4.2 K, the lifetime variation as a function of excited classes of symmetry is governed by the radiative process probability as well as the energy transfer between uranium ions in different sites. At higher temperature, a model based on a Boltzmann equilibrium between closed energy levels is able to reproduce the experimental lifetime variation as a function of the temperature, for a given class of symmetry. For the variation of lifetime as a function of uranium ion concentrations, at high dilution and in the case of U 4+ : ThBr 4 , there is a competition between the energy transfer and thermal population of excited states [fr

  1. Scale-invariant instantons and the complete lifetime of the standard model

    Science.gov (United States)

    Andreassen, Anders; Frost, William; Schwartz, Matthew D.

    2018-03-01

    In a classically scale-invariant quantum field theory, tunneling rates are infrared divergent due to the existence of instantons of any size. While one expects such divergences to be resolved by quantum effects, it has been unclear how higher-loop corrections can resolve a problem appearing already at one loop. With a careful power counting, we uncover a series of loop contributions that dominate over the one-loop result and sum all the necessary terms. We also clarify previously incomplete treatments of related issues pertaining to global symmetries, gauge fixing, and finite mass effects. In addition, we produce exact closed-form solutions for the functional determinants over scalars, fermions, and vector bosons around the scale-invariant bounce, demonstrating manifest gauge invariance in the vector case. With these problems solved, we produce the first complete calculation of the lifetime of our Universe: 1 0139 years . With 95% confidence, we expect our Universe to last more than 1 058 years . The uncertainty is part experimental uncertainty on the top quark mass and on αs and part theory uncertainty from electroweak threshold corrections. Using our complete result, we provide phase diagrams in the mt/mh and the mt/αs planes, with uncertainty bands. To rule out absolute stability to 3 σ confidence, the uncertainty on the top quark pole mass would have to be pushed below 250 MeV or the uncertainty on αs(mZ) pushed below 0.00025.

  2. Precision analysis for standard deviation measurements of immobile single fluorescent molecule images.

    Science.gov (United States)

    DeSantis, Michael C; DeCenzo, Shawn H; Li, Je-Luen; Wang, Y M

    2010-03-29

    Standard deviation measurements of intensity profiles of stationary single fluorescent molecules are useful for studying axial localization, molecular orientation, and a fluorescence imaging system's spatial resolution. Here we report on the analysis of the precision of standard deviation measurements of intensity profiles of single fluorescent molecules imaged using an EMCCD camera.We have developed an analytical expression for the standard deviation measurement error of a single image which is a function of the total number of detected photons, the background photon noise, and the camera pixel size. The theoretical results agree well with the experimental, simulation, and numerical integration results. Using this expression, we show that single-molecule standard deviation measurements offer nanometer precision for a large range of experimental parameters.

  3. Demonstration of the lack of cytotoxicity of unmodified and folic acid modified graphene oxide quantum dots, and their application to fluorescence lifetime imaging of HaCaT cells.

    Science.gov (United States)

    Goreham, Renee V; Schroeder, Kathryn L; Holmes, Amy; Bradley, Siobhan J; Nann, Thomas

    2018-01-24

    The authors describe the synthesis of water-soluble and fluorescent graphene oxide quantum dots via acid exfoliation of graphite nanoparticles. The resultant graphene oxide quantum dots (GoQDs) were then modified with folic acid. Folic acid receptors are overexpressed in cancer cells and hence can bind to functionalized graphene oxide quantum dots. On excitation at 305 nm, the GoQDs display green fluorescence with a peak wavelength at ~520 nm. The modified GoQDs are non-toxic to macrophage cells even after prolonged exposure and high concentrations. Fluorescence lifetime imaging and multiphoton microscopy was used (in combination) to image HeCaT cells exposed to GoQDs, resulting in a superior method for bioimaging. Graphical abstract Schematic representation of graphene oxide quantum dots, folic acid modified graphene oxide quantum dots (red), and the use of fluorescence lifetime to discriminate against green auto-fluorescence of HeCaT cells.

  4. An Automated System for the Control of, and Data Acquisition from Multiphoton Ionization and Fluorescence Lifetime Measurements.

    Science.gov (United States)

    1986-09-01

    Quanta- Ray company , which also supplied the laser used for the multiphoton work. The, burner was mounted on a translator stage from Velmex, Inc...and no longer exists as a process in the system. When the user analysis program has completed, the lifetime program is again automatically re-started...KCHAR) RETURN 100 FORMAT(I3) 101 FORMAT(F7.2) END SUBROUTINE LAB4 FODA SE"oteD C This routine puts the label "INTEGRAL FROM DATA SET" on the MDP C screen

  5. Rhodium self-powered neutron detector's lifetime for korean standard nuclear power plants

    International Nuclear Information System (INIS)

    Yoo, Choon Sung; Kim, Byoung Chul; Park, Jong Ho; Fero, Arnold H.; Anderson, S. L.

    2005-01-01

    A method to estimate the relative sensitivity of a self-powered rhodium detector for an upcoming cycle is developed by combining the rhodium depletion data from a nuclear design with the site measurement data. This method can be used both by nuclear power plant designers and by site staffs of Korean standard nuclear power plants for determining which rhodium detectors should be replaced during overhauls

  6. Distinct roles of the photosystem II protein PsbS and zeaxanthin in the regulation of light harvesting in plants revealed by fluorescence lifetime snapshots.

    Science.gov (United States)

    Sylak-Glassman, Emily J; Malnoë, Alizée; De Re, Eleonora; Brooks, Matthew D; Fischer, Alexandra Lee; Niyogi, Krishna K; Fleming, Graham R

    2014-12-09

    The photosystem II (PSII) protein PsbS and the enzyme violaxanthin deepoxidase (VDE) are known to influence the dynamics of energy-dependent quenching (qE), the component of nonphotochemical quenching (NPQ) that allows plants to respond to fast fluctuations in light intensity. Although the absence of PsbS and VDE has been shown to change the amount of quenching, there have not been any measurements that can detect whether the presence of these proteins alters the type of quenching that occurs. The chlorophyll fluorescence lifetime probes the excited-state chlorophyll relaxation dynamics and can be used to determine the amount of quenching as well as whether two different genotypes with the same amount of NPQ have similar dynamics of excited-state chlorophyll relaxation. We measured the fluorescence lifetimes on whole leaves of Arabidopsis thaliana throughout the induction and relaxation of NPQ for wild type and the qE mutants, npq4, which lacks PsbS; npq1, which lacks VDE and cannot convert violaxanthin to zeaxanthin; and npq1 npq4, which lacks both VDE and PsbS. These measurements show that although PsbS changes the amount of quenching and the rate at which quenching turns on, it does not affect the relaxation dynamics of excited chlorophyll during quenching. In addition, the data suggest that PsbS responds not only to ΔpH but also to the Δψ across the thylakoid membrane. In contrast, the presence of VDE, which is necessary for the accumulation of zeaxanthin, affects the excited-state chlorophyll relaxation dynamics.

  7. Fluorescence lifetime selectivity in excitation-emission matrices for qualitative analysis of a two-component system

    International Nuclear Information System (INIS)

    Millican, D.W.; McGown, L.B.

    1989-01-01

    Steady-state fluorescence excitation-emission matrices (EEMs), and phase-resolved EEMs (PREEMs) collected at modulation frequencies of 6, 18, and 30 MHz, were used for qualitative analysis of mixtures of benzo[k]fluoranthene (τ = 8 ns) and benzo[b]fluoranthene (τ = 29 ns) in ethanol. The EEMs of the individual components were extracted from mixture EEMs by means of wavelength component vector-gram (WCV) analysis. Phase resolution was found to be superior to steady-state measurements for extraction of the component spectra, for mixtures in which the intensity contributions from the two components are unequal

  8. Preparation of uranium standard solutions for x-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Wong, C.M.; Cate, J.L.; Pickles, W.L.

    1978-03-01

    A method has been developed for gravimetrically preparing uranium nitrate standards with an estimated mean error of 0.1% (1 sigma) and a maximum error of 0.2% (1 sigma) for the total uranium weight. Two source materials, depleted uranium dioxide powder and NBS Standard Reference Material 960 uranium metal, were used to prepare stock solutions. The NBS metal proved to be superior because of the small but inherent uncertainty in the stoichiometry of the uranium oxide. These solutions were used to prepare standards in a freeze-dried configuration suitable for x-ray fluorescence analysis. Both gravimetric and freeze-drying techniques are presented. Volumetric preparation was found to be unsatisfactory for 0.1% precision for the sample size of interest. One of the primary considerations in preparing uranium standards for x-ray fluorescence analysis is the development of a technique for dispensing a 50-μl aliquot of a standard solution with a precision of 0.1% and an accuracy of 0.1%. The method developed corrects for variation in aliquoting and for evaporation loss during weighing. Two sets, each containing 50 standards have been produced. One set has been retained by LLL and one set retained by the Savannah River project

  9. Penetration of silver nanoparticles into porcine skin ex vivo using fluorescence lifetime imaging microscopy, Raman microscopy, and surface-enhanced Raman scattering microscopy.

    Science.gov (United States)

    Zhu, Yongjian; Choe, Chun-Sik; Ahlberg, Sebastian; Meinke, Martina C; Alexiev, Ulrike; Lademann, Juergen; Darvin, Maxim E

    2015-05-01

    In order to investigate the penetration depth of silver nanoparticles (Ag NPs) inside the skin, porcine ears treated with Ag NPs are measured by two-photon tomography with a fluorescence lifetime imaging microscopy (TPT-FLIM) technique, confocal Raman microscopy (CRM), and surface-enhanced Raman scattering (SERS) microscopy. Ag NPs are coated with poly-N-vinylpyrrolidone and dispersed in pure water solutions. After the application of Ag NPs, porcine ears are stored in the incubator for 24 h at a temperature of 37°C. The TPT-FLIM measurement results show a dramatic decrease of the Ag NPs' signal intensity from the skin surface to a depth of 4 μm. Below 4 μm, the Ag NPs' signal continues to decline, having completely disappeared at 12 to 14 μm depth. CRM shows that the penetration depth of Ag NPs is 11.1 ± 2.1 μm. The penetration depth measured with a highly sensitive SERS microscopy reaches 15.6 ± 8.3 μm. Several results obtained with SERS show that the penetration depth of Ag NPs can exceed the stratum corneum (SC) thickness, which can be explained by both penetration of trace amounts of Ag NPs through the SC barrier and by the measurements inside the hair follicle, which cannot be excluded in the experiment.

  10. Development of suitable plastic standards for X-ray fluorescence analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mans, Christian [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: c.mans@fh-muenster.de; Hanning, Stephanie [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: hanning@fh-muenster.de; Simons, Christoph [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: simons@fh-muenster.de; Wegner, Anne [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: awegner@fh-muenster.de; Janssen, Anton [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: janssena@fh-muenster.de; Kreyenschmidt, Martin [University of Applied Sciences Muenster, Department of Chemical Engineering, Advanced Analytical Chemistry, Stegerwaldstr. 39, 48565 Steinfurt (Germany)], E-mail: martin.kreyenschmidt@fh-muenster.de

    2007-02-15

    For the adoption of the EU directive 'Restriction on use of certain Hazardous Substances' and 'Waste Electrical and Electronic Equipment' using X-ray fluorescence analysis suitable standard materials are required. Plastic standards based on acrylonitrile-butadiene-styrene terpolymer, containing the regulated elements Br, Cd, Cr, Hg and Pb were developed and produced as granulates and solid bodies. The calibration materials were not generated as a dilution from one master batch but rather the element concentrations were distributed over nine independent calibration samples. This was necessary to enable inter-elemental corrections and empirical constant mass absorption coefficients. The produced standard materials are characterized by a homogenous element distribution, which is more than sufficient for X-ray fluorescence analysis. Concentrations for all elements except for Br could be determined by Inductively Coupled Plasma Atomic Emission Spectroscopy after microwave assisted digestion. The concentration of Br was determined by use of Neutron Activation Analysis at Hahn-Meitner-Institute in Berlin, Germany. The correlation of the X-ray fluorescence analysis measurements with the values determined using Inductively Coupled Plasma Atomic Emission Spectroscopy and Neutron Activation Analysis showed a very good linearity.

  11. Quantitative comparison of X-ray fluorescence microtomography setups: Standard and confocal collimator apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Chukalina, M. [Institute of Microelectronics Technology RAS, 142432, Chernogolovka, Moscow District (Russian Federation)], E-mail: marina@ipmt-hpm.ac.ru; Simionovici, A. [Laboratoire de Geophysique Interne et Tectonophysique, University of Grenoble, BP 53, 38041, Grenoble (France)], E-mail: alexandre.simionovici@ujf-grenoble.fr; Zaitsev, S. [Institute of Microelectronics Technology RAS, 142432, Chernogolovka, Moscow District (Russian Federation)], E-mail: zaitsev@ipmt-hpm.ac.ru; Vanegas, C.J. [Institute of Microelectronics Technology RAS, 142432, Chernogolovka, Moscow District (Russian Federation)], E-mail: vanegas@ipmt-hpm.ac.ru

    2007-07-15

    Recently, there has been a renewed interest for fluorescence spectroscopy, as provided by modern setups which allow 2D and 3D imaging of elemental distributions. Two directions are currently under development: the SR-based fluorescence tomography in polar scanning geometry, provided by the new generation of X-ray microprobes and the confocal scanning geometry, which can be fielded in both SR and laboratory environments. The new probes bring forth a new age in fluorescence spectrometry: high resolution, high intensity and high sensitivity which allow 3D elemental mapping of volumes. The major task now is the development of these complex tools into fully quantitative probes, reproducible and straightforward for general use. In this work we analyze two X-ray fluorescence microtomography techniques: an apparatus tomography using a confocal collimator for the data collection and a standard first generation Computed Tomography (CT) in the parallel scanning scheme. We calculate the deposited dose (amount of energy deposited and distributed in the sample during the data collection time) and find the conditions for the choice of the tomography scheme.

  12. Bias in the absorption coefficient determination of a fluorescent dye, standard reference material 1932 fluorescein solution

    International Nuclear Information System (INIS)

    DeRose, Paul C.; Kramer, Gary W.

    2005-01-01

    The absorption coefficient of standard reference material[registered] (SRM[registered]) 1932, fluorescein in a borate buffer solution (pH=9.5) has been determined at λ=488.0, 490.0, 490.5 and 491.0 nm using the US national reference UV/visible spectrophotometer. The purity of the fluorescein was determined to be 97.6% as part of the certification of SRM 1932. The solution measured was prepared gravimetrically by diluting SRM 1932 with additional borate buffer. The value of the absorption coefficient was corrected for bias due to fluorescence that reaches the detector and for dye purity. Bias due to fluorescence was found to be on the order of -1% for both monochromatic and polychromatic (e.g., diode-array based) spectrophotometers

  13. High-resolution imaging of basal cell carcinoma: a comparison between multiphoton microscopy with fluorescence lifetime imaging and reflectance confocal microscopy.

    Science.gov (United States)

    Manfredini, Marco; Arginelli, Federica; Dunsby, Christopher; French, Paul; Talbot, Clifford; König, Karsten; Pellacani, Giovanni; Ponti, Giovanni; Seidenari, Stefania

    2013-02-01

    The aim of this study was to compare morphological aspects of basal cell carcinoma (BCC) as assessed by two different imaging methods: in vivo reflectance confocal microscopy (RCM) and multiphoton tomography with fluorescence lifetime imaging implementation (MPT-FLIM). The study comprised 16 BCCs for which a complete set of RCM and MPT-FLIM images were available. The presence of seven MPT-FLIM descriptors was evaluated. The presence of seven RCM equivalent parameters was scored in accordance to their extension. Chi-squared test with Fisher's exact test and Spearman's rank correlation coefficient were determined between MPT-FLIM scores and adjusted-RCM scores. MPT-FLIM and RCM descriptors of BCC were coupled to match the descriptors that define the same pathological structures. The comparison included: Streaming and Aligned elongated cells, Streaming with multiple directions and Double alignment, Palisading (RCM) and Palisading (MPT-FLIM), Typical tumor islands, and Cell islands surrounded by fibers, Dark silhouettes and Phantom islands, Plump bright cells and Melanophages, Vessels (RCM), and Vessels (MPT-FLIM). The parameters that were significantly correlated were Melanophages/Plump Bright Cells, Aligned elongated cells/Streaming, Double alignment/Streaming with multiple directions, and Palisading (MPT-FLIM)/Palisading (RCM). According to our data, both methods are suitable to image BCC's features. The concordance between MPT-FLIM and RCM is high, with some limitations due to the technical differences between the two devices. The hardest difficulty when comparing the images generated by the two imaging modalities is represented by their different field of view. © 2012 John Wiley & Sons A/S.

  14. Chemical analysis of coal by energy dispersive x-ray fluorescence utilizing artificial standards

    International Nuclear Information System (INIS)

    Wheeler, B.D.

    1982-01-01

    Accurate determinations of the elemental composition of coal by classical methods can be quite difficult and are normally very time consuming. X-ray fluorescence utilizing the powder method, however, has the ability of providing accurate and rapid analyses. Unfortunately, well characterized standards, although available, are not plentiful. In addition, the durability of stability of ground and pelletized coal samples is poor resulting in deterioration with time. As a result, artificial coal standards were prepared from certified geological materials by fusing in lithium tetraborate in percentages approximating expected ash contents and compositions in coal. Since the lithium tetraborate comprises about the same percentage of the standard as does the carbon, hydrogen, and oxygen in coal, the ground and pelletized coal sample can be assayed against the fused calibration curves by compensating for the differences in the mass absorption coefficients of the two matrices. 5 figures, 4 tables

  15. Nuclear lifetimes

    International Nuclear Information System (INIS)

    Caraca, J.M.G.

    1976-01-01

    The importance of the results obtained in experiments of measurement of lifetimes for a detailed knowledge of nuclear structure is referred. Direct methods of measurement of nuclear lifetimes are described, namely, electronic methods, recoil-distance method, doppler shift atenuation method and blocking-method. A brief reference is made to indirect methods for measurement of life-times

  16. Standard Practice for Use of a Lif Photo-Fluorescent Film Dosimetry System

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This practice covers the handling, testing, and procedure for using a lithium fluoride (LiF)-based photo-fluorescent film dosimetry system to measure absorbed dose (relative to water) in materials irradiated by photons or electrons. Other alkali halides that may also exhibit photofluorescence (for example, NaCl, NaF, and KCl) are not covered in this practice. Although various alkali halides have been used for dosimetry for years utilizing thermoluminescence, the use of photoluminescence is relatively new. 1.2 This practice applies to photo-fluorescent film dosimeters (referred hereafter as photo-fluorescent dosimeters) that can be used within part or all of the following ranges: 1.2.1 Absorbed dose range of 5 10-2 to 3 102 kGy (1-3). 1.2.2 Absorbed dose rate range of 0.3 to 2 10 4 Gy/s (2-5)). 1.2.3 Radiation energy range for photons of 0.05 to 10 MeV (2). 1.2.4 Radiation energy range for electrons of 0.1 to 10 MeV (2). 1.2.5 Radiation temperature range of -20 to +60°C (6,7). 1.3 This standard doe...

  17. Study on residential appliances energy efficiency standards Refrigerators, air-conditioners, incandescent lamps, fluorescent lamps, color TVs

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.G.; Cho, S.K.; Choi, S.H.; Jung, B.M.; Han, S.B.; Kim, K.D. [Korea Inst. of Energy Research, Taejon (Korea, Republic of)

    1995-12-01

    The energy efficiency standards and rating act, as amended by the rational energy utilization act, provides energy efficiency standards and ratings for 6 types of consumer products(refrigerators, air-conditioners, fluorescent lamps, incandescent lamps, ballasts and cars) authorizes the Ministry of Trade, Industry and Energy(MOTIE) to prescribe amended or new energy efficiency standards and rating standards. This study was initiated by the KIER in 1992. KIER`s assessment of the standards is designed to evaluate their statistical and engineering analysis according to Korean(Industrial) Standards(KS). And to make distinction between the poor efficiency and good efficiency models, 5 grades are classified depending on their tested energy efficiency. This year, based on our analysis, MOTIE mandated updated standards for refrigerators, air-conditioners, incandescent lamps, and fluorescent lamps. Also the objective of this study is to set the energy efficiency standards and to grade for color TV sets. (author). 37 refs., 89 figs., 85 tabs.

  18. Lifetime measurements

    International Nuclear Information System (INIS)

    Fossan, D.B.; Warburton, E.K.

    1974-01-01

    Lifetime measurements are discussed, concentrating on the electronic technique, the recoil distance method (RDM), and the Doppler shift attenuation method (DSAM). A brief review of several indirect timing techniques is given, and their specific advantages and applicability are considered. The relationship between lifetimes of nuclear states and the nuclear structure information obtained from them is examined. A short discussion of channeling and microwave methods of lifetime measurement is presented. (23 figures, 171 references) (U.S.)

  19. Quantitative micro x-ray fluorescence analyses without reference standard material; Referenzprobenfreie quantitative Mikro-Roentgenfluoreszenzanalyse

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Timo

    2009-07-15

    X-ray fluorescence analysis (XRF) is a standard method for non-destructive investigations. Due to the development of polycapillary optics and SDDdetectors requiring no cooling with liquid nitrogen, XRF becomes a suitable method for a large number of applications, e. g. for the analysis of objects in arts and archaeology. Spectrometers developed for those purposes allow investigations outside of laboratories und provide excitation areas with diameters of 10-70 {mu}m. In most applications, quantification of XRF data is realized by the usage of standard reference materials. Due to absorption processes in the samples the accuracy of the results depends strongly on the similarity of the sample and the reference standard. In cases where no suitable references are available, quantification can be done based on the ''fundamental parameter (fp) method''. This quantification procedure is based on a set of equations describing the fluorescence production and detection mathematical. The cross sections for the interaction of x-rays with matter can be taken from different databases. During an iteration process the element concentrations can be determined. Quantitative XRF based on fundamental parameters requires an accurate knowledge of the excitation spectrum. In case of a conventional setup this spectrum is given by the X-ray tube spectrum and can be calculated. The use of polycapillary optics in micro-XRF spectrometers changes the spectral distribution of the excitation radiation. For this reason it is necessary to access the transmission function of the used optic. The aim of this work is to find a procedure to describe this function for routine quantification based on fundamental parameters. Most of the measurements have been carried out using a commercial spectrometer developed for applications in arts and archaeology. On the one hand the parameters of the lens, used in the spectrometer, have been investigated by different experimental characterization

  20. Determinations of silicon and phosphorus in Pepperbush standard reference material by neutron activation and x-ray fluorescence methods

    International Nuclear Information System (INIS)

    Mizumoto, Yoshihiko; Nishio, Hirofumi; Hayashi, Takeshi; Kusakabe, Toshio; Iwata, Shiro.

    1987-01-01

    Silicon and phosphorus contents in Pepperbush standard reference material were determined by neutron activation and X-ray fluorescence methods. In neutron activation analysis, β-ray spectra of 32 P produced by 31 P(n,γ) 32 P reaction on Pepperbush and standard samples were measured by a low background β-ray spectrometer. In X-ray fluorescence analysis, the standard samples were prepared by mixing the Pepperbush powder with silicon dioxide and diammonium hydrogenphosphate. Characteristic X-rays from the samples were analyzed by a wavelength dispersive X-ray fluorescence spectrometer. From the β and X-ray intensities, silicon and phosphorus contents in Pepperbush were determined to be 1840 ± 80 and 1200 ± 50 μg g -1 , respectively. (author)

  1. Accurate Rapid Lifetime Determination on Time-Gated FLIM Microscopy with Optical Sectioning.

    Science.gov (United States)

    Silva, Susana F; Domingues, José Paulo; Morgado, António Miguel

    2018-01-01

    Time-gated fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to assess the biochemistry of cells and tissues. When applied to living thick samples, it is hampered by the lack of optical sectioning and the need of acquiring many images for an accurate measurement of fluorescence lifetimes. Here, we report on the use of processing techniques to overcome these limitations, minimizing the acquisition time, while providing optical sectioning. We evaluated the application of the HiLo and the rapid lifetime determination (RLD) techniques for accurate measurement of fluorescence lifetimes with optical sectioning. HiLo provides optical sectioning by combining the high-frequency content from a standard image, obtained with uniform illumination, with the low-frequency content of a second image, acquired using structured illumination. Our results show that HiLo produces optical sectioning on thick samples without degrading the accuracy of the measured lifetimes. We also show that instrument response function (IRF) deconvolution can be applied with the RLD technique on HiLo images, improving greatly the accuracy of the measured lifetimes. These results open the possibility of using the RLD technique with pulsed diode laser sources to determine accurately fluorescence lifetimes in the subnanosecond range on thick multilayer samples, providing that offline processing is allowed.

  2. Comparative study of the fatty acid binding process of a new FABP from Cherax quadricarinatus by fluorescence intensity, lifetime and anisotropy.

    Directory of Open Access Journals (Sweden)

    Jiayao Li

    Full Text Available Fatty acid-binding proteins (FABPs are small cytosolic proteins, largely distributed in invertebrates and vertebrates, which accomplish uptake and intracellular transport of hydrophobic ligands such as fatty acids. Although long chain fatty acids play multiple crucial roles in cellular functions (structural, energy metabolism, regulation of gene expression, the precise functions of FABPs, especially those of invertebrate species, remain elusive. Here, we have identified and characterized a novel FABP family member, Cq-FABP, from the hepatopancreas of red claw crayfish Cherax quadricarinatus. We report the characterization of fatty acid-binding affinity of Cq-FABP by four different competitive fluorescence-based assays. In the two first approaches, the fluorescent probe 8-Anilino-1-naphthalenesulfonate (ANS, a binder of internal cavities of protein, was used either by directly monitoring its fluorescence emission or by monitoring the fluorescence resonance energy transfer occurring between the single tryptophan residue of Cq-FABP and ANS. The third and the fourth approaches were based on the measurement of the fluorescence emission intensity of the naturally fluorescent cis-parinaric acid probe or the steady-state fluorescence anisotropy measurements of a fluorescently labeled fatty acid (BODIPY-C16, respectively. The four methodologies displayed consistent equilibrium constants for a given fatty acid but were not equivalent in terms of analysis. Indeed, the two first methods were complicated by the existence of non specific binding modes of ANS while BODIPY-C16 and cis-parinaric acid specifically targeted the fatty acid binding site. We found a relationship between the affinity and the length of the carbon chain, with the highest affinity obtained for the shortest fatty acid, suggesting that steric effects primarily influence the interaction of fatty acids in the binding cavity of Cq-FABP. Moreover, our results show that the binding affinities

  3. A Rotational BODIPY Nucleotide: An Environment-Sensitive Fluorescence-Lifetime Probe for DNA Interactions and Applications in Live-Cell Microscopy

    Czech Academy of Sciences Publication Activity Database

    Dziuba, Dmytro; Jurkiewicz, Piotr; Cebecauer, Marek; Hof, Martin; Hocek, Michal

    2016-01-01

    Roč. 55, č. 1 (2016), s. 174-178 ISSN 1433-7851 R&D Projects: GA ČR GBP206/12/G151; GA ČR(CZ) GC14-03141J Institutional support: RVO:61388963 ; RVO:61388955 Keywords : DNA * fluorescence spectroscopy * fluorescent probes * nucleosides * time-resolved spectroscopy Subject RIV: CC - Organic Chemistry ; BO - Biophysics (UFCH-W) Impact factor: 11.994, year: 2016

  4. Modelling lifetime cost consequences of toric compared with standard IOLs in cataract surgery of astigmatic patients in four European countries.

    Science.gov (United States)

    Laurendeau, C; Lafuma, A; Berdeaux, G

    2009-09-01

    To compare the lifetime costs of freeing astigmatic patients from spectacles after bilateral cataract surgery implanting toric intraocular lenses (IOLs: i.e., Acrysof Toric) versus monofocal IOLs, in France, Italy, Germany and Spain. A Markov model followed patient cohorts from cataract surgery until death. Prevalence rates of patients not needing spectacles and the types of spectacles prescribed for those requiring them were obtained from clinical trials and national surveys. The economic perspective was societal. Mortality rates were incorporated into the model. Discount rates were applied. A sensitivity analysis was performed on non-discounted costs. Fewer patients with toric IOLs needed spectacles for distance vision than patients with monofocal IOLs. With monofocal IOLs more than 66% of patients needed complex spectacles compared to less than 25% implanted with toric IOLs. In France and Italy, toric IOLs reduced overall costs relative to otherwise high spectacle costs after cataract surgery. Savings were 897.0 euros (France), 822.5 euros (Germany), 895.8 euros (Italy) and 391.6 euros (Spain), without discounting. On applying a 3% discount rate the costs became 691.7 euros, 646.4 euros, 693.9 euros and 308.2 euros, respectively. Bilateral toric IOL implants in astigmatic patients decreased spectacle dependence for distance vision and the need for complex spectacles. The economic consequences for patients depended on the national spectacle costs usually incurred after cataract surgery.

  5. Direct solid surface fluorescence spectroscopy of standard chemicals and humic acid in ternary system.

    Science.gov (United States)

    Mounier, S; Nicolodelli, G; Redon, R; Milori, D M B P

    2017-04-15

    The front face fluorescence spectroscopy is often used to quantify chemicals in well-known matrices as it is a rapid and powerful technique, with no sample preparation. However it was not used to investigate extracted organic matter like humic substances. This work aims to fully investigate for the first time front face fluorescence spectroscopy response of a ternary system including boric acid, tryptophan and humic substances, and two binaries system containing quinine sulfate or humic substance in boric acid. Pure chemicals, boric acid, tryptophan, quinine sulfate and humic acid were mixed together in solid pellet at different contents from 0 to 100% in mass. The measurement of excitation emission matrix of fluorescence (3D fluorescence) and laser induced fluorescence were then done in the front face mode. Fluorescence matrices were decomposed using the CP/PARAFAC tools after scattering treatments. Results show that for 3D fluorescence there is no specific component for tryptophan and quinine sulfate, and that humic substances lead to a strong extinction effect for mixture containing quinine sulfate. Laser induced fluorescence gives a very good but non-specific related response for both quinine sulfate and tryptophan. No humic substances fluorescence response was found, but extinction effect is observed as for 3D fluorescence. This effect is stronger for quinine sulfate than for tryptophan. These responses were modeled using a simple absorbance versus emission model. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Lifetime measurements

    International Nuclear Information System (INIS)

    Poletti, A.R.

    1976-01-01

    Recent developments in experimental methods of measuring the lifetimes of excited nuclear states is reviewed in three main areas. (a) Doppler Shift Attenuation Measurements (DSAM) Times: 10 -14 - 10 -11 sec.; (b) Recoil Distance Measurements (RDM) Times: 10 -9 - 10 -12 sec.; (c) Direct Electronic Timing Times: down to 10 -10 sec.; A measurement of an excited state lifetime can answer a large number of different questions. Two examples are discussed: (a) The determination of the lifetime of an isomeric transition in 93 Tc and its use in determining an upper limit for the magnitude of the parity non-conserving matrix element - /Hsub(PN)/17/2 + >. (b) The dependence of the strength of M2 transitions on isospin in nuclei in the 1dsub(3/2) -1fsub(7/2) region. (author)

  7. Determinations of elements in pepperbush standard reference material by neutron activation and X-ray fluorescence analyses

    International Nuclear Information System (INIS)

    Mizumoto, Yoshihiko; Okada, Takayuki; Tatsumi, Toshiya; Kusakabe, Toshio; Katsurayama, Kousuke; Iwata, Shiro.

    1988-01-01

    Elemental contents in Pepperbush standard reference material have been determined by neutron activation and X-ray fluorescence analyses. The standard samples of orchard leaves, tomato leaves, pine needles and Kale are used for the experiment. In the neutron activation analysis, gamma-ray spectra of nuclei produced by (n,γ) reaction on Pepperbush and standard samples are measured with Ge detectors. In the X-ray fluorescence analysis, the samples are excited with X-rays from X-ray tube with rhodium anode, and the characteristic X-rays from samples are measured with a proportional counter or NaI(Tl) detector. From the gamma- and X-ray intensities, the elemental contents in Pepperbush are determined. As a result, the contents of seventeen elements, such as sodium, calcium, iron, etc., in Pepperbush are determined. (author)

  8. Precision lifetime measurements

    International Nuclear Information System (INIS)

    Tanner, C.E.

    1994-01-01

    Precision measurements of atomic lifetimes provide important information necessary for testing atomic theory. The authors employ resonant laser excitation of a fast atomic beam to measure excited state lifetimes by observing the decay-in-flight of the emitted fluorescence. A similar technique was used by Gaupp, et al., who reported measurements with precisions of less than 0.2%. Their program includes lifetime measurements of the low lying p states in alkali and alkali like systems. Motivation for this work comes from a need to test the atomic many-body-perturbation theory (MBPT) that is necessary for interpretation of parity nonconservation experiments in atomic cesium. The authors have measured the cesium 6p 2 P 1/2 and 6p 2 P 3/2 state lifetimes to be 34.934±0.094 ns and 30.499±0.070 ns respectively. With minor changes to the apparatus, they have extended their measurements to include the lithium 2p 2 P 1/2 and 2p 2 P 3/2 states

  9. Standard coupling unification in SO(10), hybrid seesaw neutrino mass and leptogenesis, dark matter, and proton lifetime predictions

    Energy Technology Data Exchange (ETDEWEB)

    Parida, M.K.; Nayak, Bidyut Prava; Satpathy, Rajesh [Centre of Excellence in Theoretical and Mathematical Sciences,Siksha ‘O’ Anusandhan University,Khandagiri Square, Bhubaneswar 751030 (India); Awasthi, Ram Lal [Indian Institute of Science Education and Research,Knowledge City, Sector 81, SAS Nagar, Manauli 140306 (India)

    2017-04-12

    We discuss gauge coupling unification of SU(3){sub C}×SU(2){sub L}×U(1){sub Y} descending directly from non-supersymmetric SO(10) while providing solutions to the three outstanding problems of the standard model: neutrino masses, dark matter, and the baryon asymmetry of the universe. Conservation of matter parity as gauged discrete symmetry for the stability and identification of dark matter in the model calls for high-scale spontaneous symmetry breaking through 126{sub H} Higgs representation. This naturally leads to the hybrid seesaw formula for neutrino masses mediated by heavy scalar triplet and right-handed neutrinos. Being quadratic in the Majorana coupling, the seesaw formula predicts two distinct patterns of right-handed neutrino masses, one hierarchical and another not so hierarchical (or compact), when fitted with the neutrino oscillation data. Predictions of the baryon asymmetry via leptogenesis are investigated through the decays of both the patterns of RHν masses. A complete flavor analysis has been carried out to compute CP-asymmetries including washouts and solutions to Boltzmann equations have been utilised to predict the baryon asymmetry. The additional contribution to vertex correction mediated by the heavy left-handed triplet scalar is noted to contribute as dominantly as other Feynman diagrams. We have found successful predictions of the baryon asymmetry for both the patterns of right-handed neutrino masses. The SU(2){sub L} triplet fermionic dark matter at the TeV scale carrying even matter parity is naturally embedded into the non-standard fermionic representation 45{sub F} of SO(10). In addition to the triplet scalar and the triplet fermion, the model needs a nonstandard color octet fermion of mass ∼5×10{sup 7} GeV to achieve precision gauge coupling unification at the GUT mass scale M{sub U}{sup 0}=10{sup 15.56} GeV. Threshold corrections due to superheavy components of 126{sub H} and other representations are estimated and found to be

  10. FUNDUS AUTOFLUORESCENCE LIFETIMES AND CENTRAL SEROUS CHORIORETINOPATHY.

    Science.gov (United States)

    Dysli, Chantal; Berger, Lieselotte; Wolf, Sebastian; Zinkernagel, Martin S

    2017-11-01

    To quantify retinal fluorescence lifetimes in patients with central serous chorioretinopathy (CSC) and to identify disease specific lifetime characteristics over the course of disease. Forty-seven participants were included in this study. Patients with central serous chorioretinopathy were imaged with fundus photography, fundus autofluorescence, optical coherence tomography, and fluorescence lifetime imaging ophthalmoscopy (FLIO) and compared with age-matched controls. Retinal autofluorescence was excited using a 473-nm blue laser light and emitted fluorescence light was detected in 2 distinct wavelengths channels (498-560 nm and 560-720 nm). Clinical features, mean retinal autofluorescence lifetimes, autofluorescence intensity, and corresponding optical coherence tomography (OCT) images were further analyzed. Thirty-five central serous chorioretinopathy patients with a mean visual acuity of 78 ETDRS letters (range, 50-90; mean Snellen equivalent: 20/32) and 12 age-matched controls were included. In the acute stage of central serous chorioretinopathy, retinal fluorescence lifetimes were shortened by 15% and 17% in the respective wavelength channels. Multiple linear regression analysis showed that fluorescence lifetimes were significantly influenced by the disease duration (P autofluorescence lifetimes, particularly in eyes with retinal pigment epithelial atrophy, were associated with poor visual acuity. This study establishes that autofluorescence lifetime changes occurring in central serous chorioretinopathy exhibit explicit patterns which can be used to estimate perturbations of the outer retinal layers with a high degree of statistical significance.

  11. Upgrading the GSI beamline microscope with a confocal fluorescence lifetime scanner to monitor charged particle induced chromatin decondensation in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdollahi, Elham; Taucher-Scholz, Gisela [Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Durante, Marco [Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Institute for Condensed Matter Physics, Darmstadt University of Technology, 64289 Darmstadt (Germany); Jakob, Burkhard, E-mail: B.Jakob@gsi.de [Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany)

    2015-12-15

    We report the upgrade of the GSI beamline microscope coupled to the linear accelerator UNILAC by a confocal FLIM scanner utilizing time correlated single photon counting technique (TCSPC). The system can now be used to address the radiation induced chromatin decondensation in more detail and with higher sensitivity compared to intensity based methods. This decondensation of heterochromatic areas is one of the early DNA damage responses observed after charged particle irradiation and might facilitate the further processing of the induced lesions. We describe here the establishment of different DNA dyes as chromatin compaction probes usable for quantification of the DNA condensation status in living cells utilizing lifetime imaging. In addition, we find an evidence of heterochromatic chromatin decondensation in ion irradiated murine chromocenters detected after subsequent fixation using FLIM measurements.

  12. An automated wide-field time-gated optically sectioning fluorescence lifetime imaging multiwell plate reader for high-content analysis of protein-protein interactions

    Science.gov (United States)

    Alibhai, Dominic; Kumar, Sunil; Kelly, Douglas; Warren, Sean; Alexandrov, Yuriy; Munro, Ian; McGinty, James; Talbot, Clifford; Murray, Edward J.; Stuhmeier, Frank; Neil, Mark A. A.; Dunsby, Chris; French, Paul M. W.

    2011-03-01

    We describe an optically-sectioned FLIM multiwell plate reader that combines Nipkow microscopy with wide-field time-gated FLIM, and its application to high content analysis of FRET. The system acquires sectioned FLIM images in fluorescent protein. It has been applied to study the formation of immature HIV virus like particles (VLPs) in live cells by monitoring Gag-Gag protein interactions using FLIM FRET of HIV-1 Gag transfected with CFP or YFP. VLP formation results in FRET between closely packed Gag proteins, as confirmed by our FLIM analysis that includes automatic image segmentation.

  13. A step towards standardization: A method for end-point titer determination by fluorescence index of an automated microscope. End-point titer determination by fluorescence index.

    Science.gov (United States)

    Carbone, Teresa; Gilio, Michele; Padula, Maria Carmela; Tramontano, Giuseppina; D'Angelo, Salvatore; Pafundi, Vito

    2018-05-01

    Indirect Immunofluorescence (IIF) is widely considered the Gold Standard for Antinuclear Antibody (ANA) screening. However, the high inter-reader variability remains the major disadvantage associated with ANA testing and the main reason for the increasing demand of the computer-aided immunofluorescence microscope. Previous studies proposed the quantification of the fluorescence intensity as an alternative for the classical end-point titer evaluation. However, the different distribution of bright/dark light linked to the nature of the self-antigen and its location in the cells result in different mean fluorescence intensities. The aim of the present study was to correlate Fluorescence Index (F.I.) with end-point titers for each well-defined ANA pattern. Routine serum samples were screened for ANA testing on HEp-2000 cells using Immuno Concepts Image Navigator System, and positive samples were serially diluted to assign the end-point titer. A comparison between F.I. and end-point titers related to 10 different staining patterns was made. According to our analysis, good technical performance of F.I. (97% sensitivity and 94% specificity) was found. A significant correlation between quantitative reading of F.I. and end-point titer groups was observed using Spearman's test and regression analysis. A conversion scale of F.I. in end-point titers for each recognized ANA-pattern was obtained. The Image Navigator offers the opportunity to improve worldwide harmonization of ANA test results. In particular, digital F.I. allows quantifying ANA titers by using just one sample dilution. It could represent a valuable support for the routine laboratory and an effective tool to reduce inter- and intra-laboratory variability. Copyright © 2018. Published by Elsevier B.V.

  14. Standard practice for fluorescent liquid penetrant testing using the Solvent-Removable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for fluorescent penetrant examination utilizing the solvent-removable process. It is a nondestructive testing method for detecting discontinuities that are open to the surface, such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination solvent-removable process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the fluorescent solvent-removable liquid penetrant examination of materials and parts. Agreement by th...

  15. Standard practice for fluorescent liquid penetrant testing using the hydrophilic Post-Emulsification process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for fluorescent penetrant examination utilizing the hydrophilic post-emulsification process. It is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of fusion and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination hydrophilic post-emulsification process recommended or required by individual organizations can be reviewed to ascertain their applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the fluorescent penetrant examination of materials and parts using the hy...

  16. Standard practice for fluorescent liquid penetrant testing using the Water-Washable process

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for water-washable fluorescent penetrant examination of materials. It is a nondestructive testing method for detecting discontinuities that are open to the surface such as cracks, seams, laps, cold shuts, laminations, isolated porosity, through leaks, or lack of porosity and is applicable to in-process, final, and maintenance examination. It can be effectively used in the examination of nonporous, metallic materials, both ferrous and nonferrous, and of nonmetallic materials such as glazed or fully densified ceramics and certain nonporous plastics and glass. 1.2 This practice also provides a reference: 1.2.1 By which a fluorescent penetrant examination method using the water-washable process recommended or required by individual organizations can be reviewed to ascertain its applicability and completeness. 1.2.2 For use in the preparation of process specifications dealing with the water-washable fluorescent penetrant examination of materials and parts. Agreement by the purch...

  17. Optical-sectioning microscopy of protoporphyrin IX fluorescence in human gliomas: standardization and quantitative comparison with histology

    Science.gov (United States)

    Wei, Linpeng; Chen, Ye; Yin, Chengbo; Borwege, Sabine; Sanai, Nader; Liu, Jonathan T. C.

    2017-04-01

    Systemic delivery of 5-aminolevulinic acid leads to enhanced fluorescence image contrast in many tumors due to the increased accumulation of protoporphyrin IX (PpIX), a fluorescent porphyrin that is associated with tumor burden and proliferation. The value of PpIX-guided resection of malignant gliomas has been demonstrated in prospective randomized clinical studies in which a twofold greater extent of resection and improved progression-free survival have been observed. In low-grade gliomas and at the diffuse infiltrative margins of all gliomas, PpIX fluorescence is often too weak to be detected with current low-resolution surgical microscopes that are used in operating rooms. However, it has been demonstrated that high-resolution optical-sectioning microscopes are capable of detecting the sparse and punctate accumulations of PpIX that are undetectable via conventional low-power surgical fluorescence microscopes. To standardize the performance of high-resolution optical-sectioning devices for future clinical use, we have developed an imaging phantom and methods to ensure that the imaging of PpIX-expressing brain tissues can be performed reproducibly. Ex vivo imaging studies with a dual-axis confocal microscope demonstrate that these methods enable the acquisition of images from unsectioned human brain tissues that quantitatively and consistently correlate with images of histologically processed tissue sections.

  18. Highly efficient exciplex formation via radical ion pair recombination in X-irradiated alkane solutions for luminophores with short fluorescence lifetimes.

    Science.gov (United States)

    Melnikov, Anatoly R; Kalneus, Evgeny V; Korolev, Valeri V; Dranov, Igor G; Kruppa, Alexander I; Stass, Dmitri V

    2014-08-01

    X-irradiation of alkane solutions of N,N-dimethylaniline with various organic luminophores produces characteristic emission bands ascribed to the corresponding exciplexes. In contrast to optical generation, which requires diffusion-controlled quenching of excited states, an additional channel of exciplex formation via irreversible recombination of radical ion pairs is operative here, which produces exciplexes in solution with high efficiency even for p-terphenyl and diphenylacetylene having fluorescence decay times of 0.95 ns and 8 ps, respectively. The exciplex emission band is sensitive to an external magnetic field and exerts a very large observed magnetic field effect of up to 20%, the maximum possible value under the conditions of the described experiment.

  19. Confocal microscopy evaluation of stromal fluorescence intensity after standard and accelerated iontophoresis-assisted corneal cross-linking.

    Science.gov (United States)

    Lanzini, Manuela; Curcio, Claudia; Spoerl, Eberhard; Calienno, Roberta; Mastropasqua, Alessandra; Colasante, Martina; Mastropasqua, Rodolfo; Nubile, Mario; Mastropasqua, Leonardo

    2017-02-01

    The aim of this study is to determine modifications in stromal fluorescence intensity after different corneal cross-linking (CXL) procedures and to correlate stromal fluorescence to corneal biomechanical resistance. For confocal microscopy study, 15 human cadaver corneas were examined. Three served as control (group 1), three were just soaked with iontophoresis procedure (group 2), three were treated with standard epi-off technique (group 3), and six underwent iontophoresis imbibition. Three of later six were irradiated for 30 min with 3 mW/cm 2 UVA (group 4) and three for 9 min at 10 mW/cm 2 UVA (group 5). Confocal microscopy was performed to quantify the fluorescence intensity in the cornea at different stromal depths. For biomechanical study, 30 human cadaver corneas were randomly divided into five groups and treated as previously described. Static stress-strain measurements of the corneas were performed. Iontophoresis imbibition followed by 10mW/cm 2 irradiation proved to increase stromal fluorescence into the corneal stroma and significant differences were revealed between group 3 and 5 both at 100 (p = 0.0171) and 250 µm (p = 0.0024), respectively. Biomechanical analysis showed an improvement of corneal resistance in group 5. Iontophoresis imbibition followed by accelerated irradiation increased the stromal fluorescence and is related to an improvement of biomechanical resistance. This approach may represent a new strategy to achieve greater concentrations of riboflavin without removing corneal epithelium and improve clinical results while reducing the side effects of CXL.

  20. Quantitative analysis of phosphosilicate glass films on silicon wafers for calibration of x-ray fluorescence spectrometry standards

    International Nuclear Information System (INIS)

    Weissman, S.H.

    1983-01-01

    The phosphorus and silicon contents of phosphosilicate glass films deposited by chemical vapor deposition (CVD) on silicon wafers were determined. These films were prepared for use as x-ray fluorescence (XRF) spectrometry standards. The thin films were removed from the wafer by etching with dilute hydrofluoric acid, and the P and Si concentrations in solution were determined by inductively coupled plasma atomic emission spectroscopy (ICP). The calculated phosphorus concentration ranged from 2.2 to 12 wt %, with an uncertainty of 2.73 to 10.1 relative percent. Variation between the calculated weight loss (summation of P 2 O 5 and SiO 2 amounts as determined by ICP) and the measured weight loss (determined gravimetrically) averaged 4.9%. Results from the ICP method, Fourier transform-infrared spectroscopy (FT-IR), dispersive infrared spectroscopy, electron microprobe, and x-ray fluorescence spectroscopy for the same samples are compared

  1. Method of using a nuclear magnetic resonance spectroscopy standard. [SO/sub 2/ in gases by fluorescence

    Science.gov (United States)

    Spicer, L.D.; Bennett, D.W.; Davis, J.F.

    1983-05-09

    (CH/sub 3/)/sub 3/SiNSO is produced by the reaction of ((CH/sub 3/)/sub 3/SI)/sub 2/NH with SO/sub 2/. Also produced in the reaction are ((CH/sub 3/)/sub 3/Si)/sub 2/O and a new solid compound (NH/sub 4/)((CH/sub 3/)/sub 3/SiOSO/sub 2/). Both (CH/sub 3/)/sub 3/SiNSO and (NH/sub 4/)((CH/sub 3/)/sub 3/SiOSO/sub 2/) have fluorescent properties. The reaction of the subject invention is used in a method of measuring the concentration of SO/sub 2/ pollutants in gases. By the method, a sample of gas is bubbled through a solution of ((CH/sub 3/)/sub 3/Si)/sub 2/NH, whereby any SO/sub 2/ present in the gas will react to produce the two fluorescent products. The measured fluorescence of these products can then be used to calculate the concentration of SO/sub 2/ in the original gas sample. The solid product (NH/sub 4/)((CH/sub 3/)/sub 3/SiOSO/sub 2/) may be used as a standard in solid state NMR spectroscopy, wherein the resonance peaks of either /sup 1/H, /sup 13/C, /sup 15/N, or /sup 29/Si may be used as a reference.

  2. Standard test method for uranium analysis in natural and waste water by X-ray fluorescence

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This test method applies for the determination of trace uranium content in waste water. It covers concentrations of U between 0.05 mg/L and 2 mg/L. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  3. Standard test method for determination of low concentrations of uranium in oils and organic liquids by X-ray fluorescence

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers the steps necessary for the preparation and analysis by X-ray fluorescence (XRF) of oils and organic solutions containing uranium. Two different preparation techniques are described. 1.2 The procedure is valid for those solutions containing 20 to 2000 μg uranium per mL as presented to the spectrometer for the solution technique and 200 to 50 000 μg uranium per g for the pellet technique. 1.3 This test method requires the use of an appropriate internal standard. Care must be taken to ascertain that samples analyzed by this test method do not contain the internal standard or that this contamination, whenever present, has been corrected for mathematically. Such corrections are not addressed in this procedure. Care must be taken that the internal standard and sample medium are compatible; that is, samples must be miscible with tri-n-butyl phosphate (TBP) and must not remove the internal standard from solution. Alternatively, a scatter line may be used as the internal standard. 1....

  4. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  5. Electricite de France: Lifetime Project

    International Nuclear Information System (INIS)

    Combes, Jean-Pierre

    1991-01-01

    Electricite de France produces almost 80% of its electricity by means of standardized PWR nuclear power stations. Starting in 1986, therefore, a project known as the 'Lifetime Project' was developed, whose aim was initially to ensure that the lifetime defined at design stage (40 years in general) could be attained without major difficulty (follow up of the aging process). It then became apparent that it would be useful to know just how far it would be technically and economically possible to go. As a result, the project is now working towards increasing the lifetime of power stations. (author)

  6. Standard test methods for chemical analysis of ceramic whiteware materials using wavelength dispersive X-Ray fluorescence spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 These test methods cover the determination of ten major elements (SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, TiO2, P2O5, MnO, and LOI in ceramic whitewares clays and minerals using wavelength dispersive X-ray fluorescence spectrometry (WDXRF). The sample is first ignited, then fused with lithium tetraborate and the resultant glass disc is introduced into a wavelength dispersive X-ray spectrometer. The disc is irradiated with X-rays from an X-ray tube. X-ray photons emitted by the elements in the samples are counted and concentrations determined using previously prepared calibration standards. (1) In addition to 10 major elements, the method provides a gravimetric loss-on-ignition. Note 1—Much of the text of this test method is derived directly from Major element analysis by wavelength dispersive X-ray fluorescence spectrometry, included in Ref (1). 1.2 Interferences, with analysis by WDXRF, may result from mineralogical or other structural effects, line overlaps, and matrix effects. The structure of the...

  7. Multimodal fluorescence imaging spectroscopy

    NARCIS (Netherlands)

    Stopel, Martijn H W; Blum, Christian; Subramaniam, Vinod; Engelborghs, Yves; Visser, Anthonie J.W.G.

    2014-01-01

    Multimodal fluorescence imaging is a versatile method that has a wide application range from biological studies to materials science. Typical observables in multimodal fluorescence imaging are intensity, lifetime, excitation, and emission spectra which are recorded at chosen locations at the sample.

  8. Standard test method for analysis of uranium and thorium in soils by energy dispersive X-Ray fluorescence spectroscopy

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers the energy dispersive X-ray fluorescence (EDXRF) spectrochemical analysis of trace levels of uranium and thorium in soils. Any sample matrix that differs from the general ground soil composition used for calibration (that is, fertilizer or a sample of mostly rock) would have to be calibrated separately to determine the effect of the different matrix composition. 1.2 The analysis is performed after an initial drying and grinding of the sample, and the results are reported on a dry basis. The sample preparation technique used incorporates into the sample any rocks and organic material present in the soil. This test method of sample preparation differs from other techniques that involve tumbling and sieving the sample. 1.3 Linear calibration is performed over a concentration range from 20 to 1000 μg per gram for uranium and thorium. 1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are for information only. 1.5 This standard...

  9. Statistical filtering in fluorescence microscopy and fluorescence correlation spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Macháň, Radek; Kapusta, Peter; Hof, Martin

    Roč. 406 , č. 20 (2014), s. 4797-4813 ISSN 1618-2642 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : Filtered fluorescence correlation spectroscopy * Fluorescence lifetime correlation spectroscopy * Fluorescence spectral correlation spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.436, year: 2014

  10. B meson lifetime measurement

    International Nuclear Information System (INIS)

    Piccolo, M.

    1989-01-01

    The lifetime of hadrons containing b-quark has been the subject of extensive experimental work and theoretical speculation; its importance is due to implications on some of the fundamental parameters of the Standard Model, such as the top quark mass and the mixing angles. Since the pioneer measurements of the MAC and MARK II collaborations at PEP in 1983 the progress has been impressive; but many issues still remain open and await further study. In this paper the field's present status is discussed. An overview of the theoretical motivations for this measurements in the Standard Model framework is done. Then the experimental techniques used are reviewed, emphasizing the most recent measurements. A comparison of the results obtained is done and systematic errors are discussed. In conclusion there are some remarks on the further developments foreseen in the near future

  11. A multicenter study to standardize reporting and analyses of fluorescence-activated cell-sorted murine intestinal epithelial cells

    Science.gov (United States)

    Magness, Scott T.; Puthoff, Brent J.; Crissey, Mary Ann; Dunn, James; Henning, Susan J.; Houchen, Courtney; Kaddis, John S.; Kuo, Calvin J.; Li, Linheng; Lynch, John; Martin, Martin G.; May, Randal; Niland, Joyce C.; Olack, Barbara; Qian, Dajun; Stelzner, Matthias; Swain, John R.; Wang, Fengchao; Wang, Jiafang; Wang, Xinwei; Yan, Kelley; Yu, Jian

    2013-01-01

    Fluorescence-activated cell sorting (FACS) is an essential tool for studies requiring isolation of distinct intestinal epithelial cell populations. Inconsistent or lack of reporting of the critical parameters associated with FACS methodologies has complicated interpretation, comparison, and reproduction of important findings. To address this problem a comprehensive multicenter study was designed to develop guidelines that limit experimental and data reporting variability and provide a foundation for accurate comparison of data between studies. Common methodologies and data reporting protocols for tissue dissociation, cell yield, cell viability, FACS, and postsort purity were established. Seven centers tested the standardized methods by FACS-isolating a specific crypt-based epithelial population (EpCAM+/CD44+) from murine small intestine. Genetic biomarkers for stem/progenitor (Lgr5 and Atoh 1) and differentiated cell lineages (lysozyme, mucin2, chromogranin A, and sucrase isomaltase) were interrogated in target and control populations to assess intra- and intercenter variability. Wilcoxon's rank sum test on gene expression levels showed limited intracenter variability between biological replicates. Principal component analysis demonstrated significant intercenter reproducibility among four centers. Analysis of data collected by standardized cell isolation methods and data reporting requirements readily identified methodological problems, indicating that standard reporting parameters facilitate post hoc error identification. These results indicate that the complexity of FACS isolation of target intestinal epithelial populations can be highly reproducible between biological replicates and different institutions by adherence to common cell isolation methods and FACS gating strategies. This study can be considered a foundation for continued method development and a starting point for investigators that are developing cell isolation expertise to study physiology and

  12. MIQE précis: Practical implementation of minimum standard guidelines for fluorescence-based quantitative real-time PCR experiments

    NARCIS (Netherlands)

    Bustin, S.A.; Beaulieu, J.F.; Huggett, J.; Jaggi, R.; Kibenge, F.S.; Olsvik, P.A.; Penning, L.C.; Toegel, S.

    2010-01-01

    MIQE précis: Practical implementation of minimum standard guidelines for fluorescence-based quantitative real-time PCR experiments Stephen A Bustin1 , Jean-François Beaulieu2 , Jim Huggett3 , Rolf Jaggi4 , Frederick SB Kibenge5 , Pål A Olsvik6 , Louis C Penning7 and Stefan Toegel8 1 Centre for

  13. Standardization and optimization of fluorescence in situ hybridization (FISH) for HER-2 assessment in breast cancer: A single center experience.

    Science.gov (United States)

    Bogdanovska-Todorovska, Magdalena; Petrushevska, Gordana; Janevska, Vesna; Spasevska, Liljana; Kostadinova-Kunovska, Slavica

    2018-05-20

    Accurate assessment of human epidermal growth factor receptor 2 (HER-2) is crucial in selecting patients for targeted therapy. Commonly used methods for HER-2 testing are immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Here we presented the implementation, optimization and standardization of two FISH protocols using breast cancer samples and assessed the impact of pre-analytical and analytical factors on HER-2 testing. Formalin fixed paraffin embedded (FFPE) tissue samples from 70 breast cancer patients were tested for HER-2 using PathVysion™ HER-2 DNA Probe Kit and two different paraffin pretreatment kits, Vysis/Abbott Paraffin Pretreatment Reagent Kit (40 samples) and DAKO Histology FISH Accessory Kit (30 samples). The concordance between FISH and IHC results was determined. Pre-analytical and analytical factors (i.e., fixation, baking, digestion, and post-hybridization washing) affected the efficiency and quality of hybridization. The overall hybridization success in our study was 98.6% (69/70); the failure rate was 1.4%. The DAKO pretreatment kit was more time-efficient and resulted in more uniform signals that were easier to interpret, compared to the Vysis/Abbott kit. The overall concordance between IHC and FISH was 84.06%, kappa coefficient 0.5976 (p characteristics. Differences in the pre-analytical and analytical steps can affect the hybridization quality and efficiency. The use of DAKO pretreatment kit is time-saving and cost-effective.

  14. Standardization and optimization of fluorescence in situ hybridization (FISH for HER-2 assessment in breast cancer: A single center experience

    Directory of Open Access Journals (Sweden)

    Magdalena Bogdanovska-Todorovska

    2018-05-01

    Full Text Available Accurate assessment of human epidermal growth factor receptor 2 (HER-2 is crucial in selecting patients for targeted therapy. Commonly used methods for HER-2 testing are immunohistochemistry (IHC and fluorescence in situ hybridization (FISH. Here we presented the implementation, optimization and standardization of two FISH protocols using breast cancer samples and assessed the impact of pre-analytical and analytical factors on HER-2 testing. Formalin fixed paraffin embedded (FFPE tissue samples from 70 breast cancer patients were tested for HER-2 using PathVysion™ HER-2 DNA Probe Kit and two different paraffin pretreatment kits, Vysis/Abbott Paraffin Pretreatment Reagent Kit (40 samples and DAKO Histology FISH Accessory Kit (30 samples. The concordance between FISH and IHC results was determined. Pre-analytical and analytical factors (i.e., fixation, baking, digestion, and post-hybridization washing affected the efficiency and quality of hybridization. The overall hybridization success in our study was 98.6% (69/70; the failure rate was 1.4%. The DAKO pretreatment kit was more time-efficient and resulted in more uniform signals that were easier to interpret, compared to the Vysis/Abbott kit. The overall concordance between IHC and FISH was 84.06%, kappa coefficient 0.5976 (p < 0.0001. The greatest discordance (82% between IHC and FISH was observed in IHC 2+ group. A standardized FISH protocol for HER-2 assessment, with high hybridization efficiency, is necessary due to variability in tissue processing and individual tissue characteristics. Differences in the pre-analytical and analytical steps can affect the hybridization quality and efficiency. The use of DAKO pretreatment kit is time-saving and cost-effective.

  15. Application of time-correlated single photon counting and stroboscopic detection methods with an evanescent-wave fibre-optic sensor for fluorescence-lifetime-based pH measurements

    International Nuclear Information System (INIS)

    Henning, Paul E; Geissinger, Peter

    2012-01-01

    Quasi-distributed optical fibre sensor arrays containing luminescent sensor molecules can be read out spatially resolved utilizing optical time-of-flight detection (OTOFD) methods, which employ pulsed laser interrogation of the luminosensors and time-resolved detection of the sensor signals. In many cases, sensing is based on a change in sensor luminescence intensity; however, sensing based on luminescence lifetime changes is preferable because it reduces the need for field calibration. Because in OTOFD detection is time-resolved, luminescence-lifetime information is already available through the signal pulses, although in practise applications were restricted to sensors with long luminescence lifetimes (hundreds of ns). To implement lifetime-based sensing in crossed-optical-fibre-sensor arrays for sensor molecules with lifetimes less than 10 ns, two time-domain methods, time-correlated single photon counting and stroboscopic detection, were used to record the pH-dependent emission of a fluorescein derivative covalently attached to a highly-porous polymer. A two-term nonexponential decay function yielded both a good fit for experimental lifetime data during reconvolution and a pH response that matches Henderson–Hasselbalch behaviour, yielding a sensor accuracy of 0.02 pH units. Moreover, strong agreement was obtained for the two lifetime determination methods and with intensity-based measurements taken previously. (paper)

  16. State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards.

    Science.gov (United States)

    Resch-Genger, Ute; Bremser, Wolfram; Pfeifer, Dietmar; Spieles, Monika; Hoffmann, Angelika; DeRose, Paul C; Zwinkels, Joanne C; Gauthier, François; Ebert, Bernd; Taubert, R Dieter; Voigt, Jan; Hollandt, Jörg; Macdonald, Rainer

    2012-05-01

    In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)-based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.8% for the corrected emission spectra. This compares well with the relative standard uncertainties of 4.2% for physical standard-based spectral corrections demonstrated in the first part of this study (previous paper in this issue) involving an international group of four expert laboratories. The excellent comparability of the measurements of the field laboratories also demonstrates the effectiveness of RM-based correction procedures.

  17. Trace element analysis of water using radioisotope induced X-ray fluorescence (Cd-109) and a preconcentration-internal standard method

    International Nuclear Information System (INIS)

    Alvarez, M.; Cano, W.

    1986-10-01

    Radioisotope induced X-ray fluorescence using Cd-109 was used for the determination of iron, nickel, copper, zinc, lead and mercury in water. These metals were concentrated by precipitation with the chelating agent APDC. The precipitated formed was filtered using a membrane filter. Cobalt was added as an internal standard. Minimum detection limit, sensitivities and calibration curves linearities have been obtained to find the limits of the method. The usefulness of the method is illustrated analysing synthetic standard solutions. As an application analytical results are given for water of a highly polluted river area. (Author)

  18. Nuclear lifetime measurement

    International Nuclear Information System (INIS)

    Guillaume, Georges

    Three direct techniques of lifetime measurement are emphasized: electronic methods and two methods based on the Doppler effect (the recoil distance methods or RDM, the Doppler shift attenuation methods or DSAM). Said direct methods are concerned with the direct measurement of the radioactive decay constants of nuclear excited states. They allow lifetimes of nucleus bound states whose deexcitations occur by electromagnetic transitions, to be determined. Other methods for measuring lifetimes are also examined: microwave techniques and those involving the blocking effect in crystals (direct methods) and also various indirect methods of obtaining lifetimes (γ resonance scattering, capture reactions, inelastic electron and nucleus scattering, and Coulomb deexcitation) [fr

  19. Lifetime of organic photovoltaics

    DEFF Research Database (Denmark)

    Corazza, Michael; Krebs, Frederik C; Gevorgyan, Suren A.

    2015-01-01

    tests. Comparison of the indoor and outdoor lifetimes was performed by means of the o-diagram, which constitutes the initial steps towards establishing a method for predicting the lifetime of an organic photovoltaic device under real operational conditions based on a selection of accelerated indoor...

  20. Lifetime of Mechanical Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Leland, K.

    1999-07-01

    The gas plant at Kaarstoe was built as part of the Statpipe gas transport system and went on stream in 1985. In 1993 another line was routed from the Sleipner field to carry condensate, and the plant was extended accordingly. Today heavy additional supply- and export lines are under construction, and the plant is extended more than ever. The main role of the factory is to separate the raw gas into commercial products and to pump or ship it to the markets. The site covers a large number of well-known mechanical equipment. This presentation deals with piping, mechanical and structural disciplines. The lifetime of mechanical equipment is often difficult to predict as it depends on many factors, and the subject is complex. Mechanical equipment has been kept in-house, which provides detailed knowledge of the stages from a new to a 14 years old plant. The production regularity has always been very high, as required. The standard of the equipment is well kept, support systems are efficient, and human improvisation is extremely valuable.

  1. Hadronization, spin and lifetimes

    International Nuclear Information System (INIS)

    Grossman, Yuval; Nachshon, Itay

    2008-01-01

    Measurements of lifetimes can be done in two ways. For very short lived particles, the width can be measured. For long lived ones, the lifetime can be directly measured, for example, using a displaced vertex. Practically, the lifetime cannot be extracted for particles with intermediate lifetimes. We show that for such cases information about the lifetime can be extracted for heavy colored particles that can be produced with known polarization. For example, a t-like particle with intermediate lifetime hadronizes into a superposition of the lowest two hadronic states, T* and T (the equivalent of B* and B). Depolarization effects are governed by time scales that are much longer than the hadronization time scale, Λ QCD -1 . After a time of order 1/Δm, with Δm≡m(T*)-m(T), half of the initial polarization is lost. The polarization is totally lost after a time of order 1/Γ γ , with Γ γ = Γ(T* → Tγ). Thus, by comparing the initial and final polarization, we get information on the particle's lifetime.

  2. Gated Detection Measurements of Phosphorescence Lifetimes

    Directory of Open Access Journals (Sweden)

    Yordan Kostov

    2004-10-01

    Full Text Available A low-cost, gated system for measurements of phosphorescence lifetimes is presented. An extensive description of the system operating principles and metrological characteristics is given. Remarkably, the system operates without optical filtering of the LED excitation source. A description of a practical system is also given and its performance is discussed. Because the device effectively suppresses high-level background fluorescence and scattered light, it is expected to find wide-spread application in bioprocess, environmental and biomedical fields.

  3. Setting up processes and standardization of the equipment in order to optimize analyses of the wavelength dispersion X-ray fluorescence (WDXRF) system

    International Nuclear Information System (INIS)

    Phan Trong Phuc; Luu Anh Tuyen; La Ly Nguyen; Nguyen Thi Ngoc Hue; Pham Thi Hue; Do Duy Khiem

    2015-01-01

    For the purpose of operating and optimizing the analyses of the equipment: wavelength dispersion X-ray fluorescence (WDXRF)- model S8 TIGER from Enhancing Equipment Project (TCTTB) 2011-2012, we set up sampling and analytical process for different sample kinds; we constructed multi-elemental calibration curve for clay sample; we analysed elemental concentrations of 5 clay samples by XRF method and compared the results with the results given by NAA method. Equipment sensitivity was tested by analysing elemental concentrations of 2 Kaolin standard samples. The results show that S8-Tiger equipment is within good condition and is able to analyze powder clay sample exactly. (author)

  4. Charmed particle lifetimes

    International Nuclear Information System (INIS)

    Rosner, J.L.

    1979-01-01

    Conventional estimates are reviewed for charmed particle lifetimes. Free-quark models give values of (a few) x 10 -13 sec to (a few) x 10 -12 sec. The shorter of these values also follows from an extrapolation based on D → Ke/sup nu/. Possible differences among the lifetimes and production rates of D 0 , D + , F + , C 0 + , the heavy lepton tau, and the fifth quark b are discussed. Extreme values of mixing angles in a six-quark model could extend charmed particle lifetimes by a factor of at most three from the above estimates, while shorter lifetimes than those predicted could occur for some species like D 0 or F + if their nonleptonic decays were enhanced. The predictions are discussed in the light of some current experimental results, and it is estimated that sigma(pp → charm) approx. = 10 μb at 400 GeV/c. 95 references

  5. Mobility-lifetime product in epitaxial GaAs X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sun, G.C. [GESEC R and D, Universite Pierre et Marie Curie, Bat.11, 140 rue de Lourmel, 75015 Paris (France)]. E-mail: guocsun@ccr.jussieu.fr; Zazoui, M. [LPMC, Faculte des Sciences et Techniques-Mohammedia, B.P. 146 Bd Hassan II, Mohammedia, Maroc (Morocco); Talbi, N. [Faculte des Sciences, Universite de Gabes, Route de Medenine, 6029 Gabes (Tunisia); Khirouni, K. [Faculte des Sciences, Universite de Gabes, Route de Medenine, 6029 Gabes (Tunisia); Bourgoin, J.C. [GESEC R and D, Universite Pierre et Marie Curie, Bat.11, 140 rue de Lourmel, 75015 Paris (France)

    2007-04-01

    Self-supported thick (200-500 {mu}m), non-intentionally doped, epitaxial GaAs layers are good candidates for X-ray imaging for the following reasons. Their electronic properties are homogeneous over large areas, they can be grown at low cost, the technology to realize pixel detectors of various size is standard, the defect concentration is low and the fluorescence yield is small. Here, we characterize the defects present in the material and evaluate the mobility-lifetime product, using Deep Level Transient Spectroscopy combined with current-voltage and charge collection measurements.

  6. Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes

    Science.gov (United States)

    Zhou, Yunyou; Bian, Guirong; Wang, Leyu; Dong, Ling; Wang, Lun; Kan, Jian

    2005-06-01

    This paper describes the preparation of organic nanoparticles by reprecipitation method under sonication and vigorous stirring. Transmission electron microscopy (TEM) was used to characterize the size and size distribution of the luminescent nanoparticles. Their average diameter was about 25 nm with a size variation of ±18%. The fluorescence decay lifetime of the nanoparticles also was determined on a self-equipped fluorospectrometer with laser light source. The lifetime (˜0.09 μs) of nanoparticles is about three times long as that of the monomer. The nanoparticles were in abundant of hydrophilic groups, which increased their miscibility in aqueous solution. These organic nanoparticles have high photochemical stability, excellent resistance to chemical degradation and photodegradation, and a good fluorescence quantum yield (25%). The fluorescence can be efficiently quenched by nucleic acids. Based on the fluorescence quenching of nanoparticles, a fluorescence quenching method was developed for determination of microamounts of nucleic acids by using the nanoparticles as a new fluorescent probe. Under optimal conditions, maximum fluorescence quenching is produced, with maximum excitation and emission wavelengths of 345 and 402 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-19.0 μg ml -1 for calf thymus DNA (ct-DNA) and 0.3-19.0 μg ml -1 for fish sperm DNA (fs-DNA). The corresponding detection limits are 0.25 μg ml -1 for ct-DNA and 0.17 μg ml -1 for fs-DNA. The relative standard deviation of six replicate measurements is 1.3-2.1%. The method is simple, rapid and sensitive with wide linear range. The recovery and relative standard deviation are very satisfactory.

  7. Time-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gustavsson, Thomas; Mialocq, Jean-Claude

    2007-01-01

    This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

  8. Measurements of heavy quark and lepton lifetimes

    International Nuclear Information System (INIS)

    Jaros, J.A.

    1985-02-01

    The PEP/PETRA energy range has proved to be well-suited for the study of the lifetimes of hadrons containing the b and c quarks and the tau lepton for several reasons. First, these states comprise a large fraction of the total interaction rate in e + e - annihilation and can be cleanly identified. Second, the storage rings have operated at high luminosity and so produced these exotic states copiously. And finally, thanks to the interplay of the Fermi coupling strength, the quark and lepton masses, and the beam energy, the expected decay lengths are in the 1/2 mm range and so are comparatively easy to measure. This pleasant coincidence of cleanly identified and abundant signal with potentially large effects has made possible the first measurements of two fundamental weak couplings, tau → nu/sub tau/W and b → cW. These measurements have provided a sharp test of the standard model and allowed, for the first time, the full determination of the magnitudes of the quark mixing matrix. This paper reviews the lifetime studies made at PEP during the past year. It begins with a brief review of the three detectors, DELCO, MAC and MARK II, which have reported lifetime measurements. Next it discusses two new measurements of the tau lifetime, and briefly reviews a measurement of the D 0 lifetime. Finally, it turns to measurements of the B lifetime, which are discussed in some detail. 18 references, 14 figures, 1 table

  9. Filter replacement lifetime prediction

    Science.gov (United States)

    Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

    2017-10-25

    Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

  10. A Satellite Mortality Study to Support Space Systems Lifetime Prediction

    Science.gov (United States)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory

    2013-01-01

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  11. Prompt Neutron Lifetime for the NBSR Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, A.L.; Diamond, D.

    2012-06-24

    In preparation for the proposed conversion of the National Institute of Standards and Technology (NIST) research reactor (NBSR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, certain point kinetics parameters must be calculated. We report here values of the prompt neutron lifetime that have been calculated using three independent methods. All three sets of calculations demonstrate that the prompt neutron lifetime is shorter for the LEU fuel when compared to the HEU fuel and longer for the equilibrium end-of-cycle (EOC) condition when compared to the equilibrium startup (SU) condition for both the HEU and LEU fuels.

  12. The neutron lifetime experiment PENeLOPE

    Energy Technology Data Exchange (ETDEWEB)

    Schreyer, Wolfgang [Technische Universitaet Muenchen (Germany); Collaboration: PENeLOPE-Collaboration

    2015-07-01

    The neutron lifetime τ{sub n}=880.3±1.1 s is an important parameter in the Standard Model of particle physics and in Big Bang cosmology. Several systematic corrections of previously published results reduced the PDG world average by several σ in the last years and call for a new experiment with complementary systematics. The experiment PENeLOPE, currently under construction at the Physik-Department of Technische Universitaet Muenchen, aims to determine the neutron lifetime with a precision of 0.1 s. It will trap ultra-cold neutrons in a magneto-gravitational trap using a large superconducting magnet and will measure their lifetime by both neutron counting and online proton detection. This presentation gives an overview over the latest developments of the experiment.

  13. B Lifetimes and Mixing

    International Nuclear Information System (INIS)

    Evans, Harold G.

    2009-01-01

    The Tevatron experiments, CDF and D0, have produced a wealth of new B-physics results since the start of Run II in 2001. We've observed new B-hadrons, seen new effects, and increased many-fold the precision with which we know the properties of b-quark systems. In these proceedings, we will discuss two of the most fruitful areas in the Tevatron B-physics program: lifetimes and mixing. We'll examine the experimental issues driving these analyses, present a summary of the latest results, and discuss prospects for the future.

  14. Lifetimes of heavy flavour particles

    International Nuclear Information System (INIS)

    Forty, R.

    1994-01-01

    The lifetimes of heavy-flavour hadrons are reviewed. After a brief discussion of the theoretical predictions, the problem of averaging lifetime measurements is discussed. The various experimental measurements are then presented and suitable averages performed. Charmed meson lifetimes are now measured to the few percent level, better that theory can predict, whilst for charmed baryons the lifetime hierarchy has been established for the first time. For beauty hadrons the lifetimes are measured at the 6-10 % level, and are in reasonable agreement with theoretical expectations. Beauty baryon studies ar just beginning. (author)

  15. Absorbance and fluorescence studies on porphyrin Nanostructures ...

    African Journals Online (AJOL)

    The aim of this work was to study some photophysical properties of PNR for application as light harvester in dye sensitized solar cells. These properties included absorbance, fluorescence, and fluorescence quantum yield and lifetime. The results of Transmission Electron Microscope (TEM) images showed the formation of ...

  16. Metabolic Mapping of Breast Cancer with Multiphoton Spectral and Lifetime Imaging

    Science.gov (United States)

    2007-03-01

    2002. Spectrally resolved fluorescence lifetime imaging microscopy. Appl. Spec- trosc. 56 :155-166. 38. Becker, W., A. Bergmann, E. Haustein , Z...photon fluores- cence lifetime imaging microscopy of macrophage-mediated antigen processing. J. Microsc. 185 :339-353. 45. Lin, H.J., P. Herman , and

  17. Autofluorescence Lifetimes in Geographic Atrophy in Patients With Age-Related Macular Degeneration.

    Science.gov (United States)

    Dysli, Chantal; Wolf, Sebastian; Zinkernagel, Martin S

    2016-05-01

    To investigate fluorescence lifetime characteristics in patients with geographic atrophy (GA) in eyes with age-related macular degeneration and to correlate the measurements with clinical data and optical coherence tomography (OCT) findings. Patients with GA were imaged with a fluorescence lifetime imaging ophthalmoscope. Retinal autofluorescence lifetimes were measured in a short and a long spectral channel (498-560 nm and 560-720 nm). Mean retinal fluorescence lifetimes were analyzed within GA and the surrounding retina, and data were correlated with best corrected visual acuity and OCT measurements. Fluorescence lifetime maps of 41 eyes of 41 patients (80 ± 7 years) with GA were analyzed. Mean lifetimes within areas of atrophy were prolonged by 624 ± 276 ps (+152%) in the short spectral channel and 418 ± 186 ps (+83%) in the long spectral channel compared to the surrounding tissue. Autofluorescence lifetime abnormalities in GA occurred with particular patterns, similar to those seen in fundus autofluorescence intensity images. Within the fovea short mean autofluorescence lifetimes were observed, presumably representing macular pigment. Short lifetimes were preserved even in the absence of foveal sparing but were decreased in patients with advanced retinal atrophy in OCT. Short lifetimes in the fovea correlated with better best corrected visual acuity in both spectral channels. This study established that autofluorescence lifetime changes in GA present with explicit patterns. We hypothesize that the short lifetimes seen within the atrophy may be used to estimate damage induced by atrophy and to monitor disease progression in the context of natural history or interventional therapeutic studies.

  18. Interlaboratory comparison of positron and positronium lifetimes in polymers

    DEFF Research Database (Denmark)

    Wastlund, C.; Eldrup, Morten Mostgaard; Maurer, F.H.J.

    1998-01-01

    A comparison of the results of a series of positron annihilation lifetime measurements performed in 12 laboratories is presented. The measurements were conducted on three different polymer samples, all prepared in one laboratory under standard conditions. The objective of the work was to gain...... insight into the variation in derived positron and positronium lifetimes and intensities measured in the different laboratories on identical specimens. Lifetime data were collected at room temperature by each laboratory following their own standard measurement and data evaluation procedures. The polymers...

  19. Solvent isotope effect on the fluorescence of azoalkanes

    International Nuclear Information System (INIS)

    Mirbach, M.J.; Mirbach, M.F.; Cherry, W.R.; Turro, N.J.; Engel, P.

    1977-01-01

    A study of fluorescence quantum yields and fluorescence lifetimes of two cyclic azoalkanes reveal a striking dependence of phisub(F) and tausub(F) on solvent and on isotopic substitution (OH → OD). A mechanism involving specific deactivation of the fluorescent state from a hydrogen bonded complex is proposed to rationalize the data. (orig./HK) [de

  20. Effect of pharmacologically induced retinal degeneration on retinal autofluorescence lifetimes in mice.

    Science.gov (United States)

    Dysli, Chantal; Dysli, Muriel; Zinkernagel, Martin S; Enzmann, Volker

    2016-12-01

    Fluorescence lifetime imaging ophthalmoscopy (FLIO) was used to investigate retinal autofluorescence lifetimes in mouse models of pharmacologically induced retinal degeneration over time. Sodium iodate (NaIO 3 , 35 mg/kg intravenously) was used to induce retinal pigment epithelium (RPE) degeneration with subsequent loss of photoreceptors (PR) whereas N-methyl-N-nitrosourea (MNU, 45 mg/kg intraperitoneally) was employed for degeneration of the photoreceptor cell layer alone. All mice were measured at day 3, 7, 14, and 28 after the respective injection of NaIO 3 , MNU or NaCl (control). Fluorescence lifetime imaging was performed using a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Heidelberg, Germany). Fluorescence was excited at 473 nm and fluorescence lifetimes were measured in a short and a long spectral channel (498-560 nm and 560-720 nm). Corresponding optical coherence tomography (OCT) images were consecutively acquired and histology was performed at the end of the experiments. Segmentation of OCT images and histology verified the cell type-specific degeneration process over time. Retinal autofluorescence lifetimes increased from day 3 to day 28 in mice after NaIO 3 treatment. Finally, at day 28, fluorescence lifetimes were prolonged by 8% in the short and 61% in the long spectral channel compared to control animals (p = 0.21 and p = 0.004, respectively). In mice after MNU treatment, the mean retinal autofluorescence lifetimes were already decreased at day 3 and retinal lifetimes were finally shortened by 27% in the short and 51% in the long spectral channel at day 28 (p = 0.0028). In conclusion, degeneration of the RPE with subsequent photoreceptor degeneration by NaIO 3 lead to longer mean fluorescence lifetimes of the retina compared to control mice, whereas during specific degeneration of the photoreceptor layer induced by MNU shorter lifetimes were measured. Therefore, short retinal fluorescence lifetimes may originate

  1. QUANTIFYING THE SHORT LIFETIME WITH TCSPC-FLIM: FIRST MOMENT VERSUS FITTING METHODS

    Directory of Open Access Journals (Sweden)

    LINGLING XU

    2013-10-01

    Full Text Available Combing the time-correlated single photon counting (TCSPC with fluorescence lifetime imaging microscopy (FLIM provides promising opportunities in revealing important information on the microenvironment of cells and tissues, but the applications are thus far mainly limited by the accuracy and precision of the TCSPC-FLIM technique. Here we present a comprehensive investigation on the performance of two data analysis methods, the first moment (M1 method and the conventional least squares (Fitting method, in quantifying fluorescence lifetime. We found that the M1 method is more superior than the Fitting method when the lifetime is short (70 ~ 400 ps or the signal intensity is weak (<103 photons.

  2. Mining the bulk positron lifetime

    International Nuclear Information System (INIS)

    Aourag, H.; Guittom, A.

    2009-01-01

    We introduce a new approach to investigate the bulk positron lifetimes of new systems based on data-mining techniques. Through data mining of bulk positron lifetimes, we demonstrate the ability to predict the positron lifetimes of new semiconductors on the basis of available semiconductor data already studied. Informatics techniques have been applied to bulk positron lifetimes for different tetrahedrally bounded semiconductors in order to discover computational design rules. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Energy Savings Lifetimes and Persistence

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Ian M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schiller, Steven R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Billingsley, Megan A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Goldman, Charles A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schwartz, Lisa C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-02-01

    This technical brief explains the concepts of energy savings lifetimes and savings persistence and discusses how program administrators use these factors to calculate savings for efficiency measures, programs and portfolios. Savings lifetime is the length of time that one or more energy efficiency measures or activities save energy, and savings persistence is the change in savings throughout the functional life of a given efficiency measure or activity. Savings lifetimes are essential for assessing the lifecycle benefits and cost effectiveness of efficiency activities and for forecasting loads in resource planning. The brief also provides estimates of savings lifetimes derived from a national collection of costs and savings for electric efficiency programs and portfolios.

  4. Positron lifetimes in deformed copper

    International Nuclear Information System (INIS)

    Hinode, Kenji; Tanigawa, Shoichiro; Doyama, Masao

    1976-01-01

    Positron lifetime measurements were performed for Cu samples with different densities of lattice defects. The lifetime spectra were successfully resolved into two components with the help of the well established analysis program. Obtained results were quite consistent with those expected from the trapping model. The positron trapping mechanism from free to trapped states and the initial condition of the model were especially checked. Deduced values obtained for tau sub(c) (lifetime of free positrons) and tau sub(t) (lifetime of trapped positrons) were 122+-5 psec and 176+-5 psec, respectively. (auth.)

  5. Lifetime measurement of the 8s level in francium

    International Nuclear Information System (INIS)

    Gomez, E.; Sprouse, G.D.; Orozco, L.A.; Galvan, A. Perez

    2005-01-01

    We measure the lifetime of the 8s level of 210 Fr atoms on a magneto-optically trapped sample with time-correlated single-photon counting. The 7P 1/2 state serves as the resonant intermediate level for two-step excitation of the 8s level completed with a 1.3-μm laser. Analysis of the fluorescence decay through the 7P 3/2 level gives 53.30±0.44 ns for the 8s level lifetime

  6. Fluorescence optical imaging and 3T-MRI for detection of synovitis in patients with rheumatoid arthritis in comparison to a composite standard of reference.

    Science.gov (United States)

    Thuermel, Klaus; Neumann, Jan; Jungmann, Pia M; Schäffeler, Christoph; Waldt, Simone; Heinze, Alexander; Beckmann, Alexander; Hauser, Christine; Hasenau, Anna-Lena; Wildgruber, Moritz; Clotten, Sigrun; Sievert, Matti; Haller, Bernhard; Woertler, Klaus; Harasser, Norbert; Rummeny, Ernst J; Meier, Reinhard

    2017-05-01

    To address whether Indocyanine Green (ICG) enhanced fluorescence optical imaging (FOI) is more sensitive than magnetic resonance imaging (MRI) in the detection of synovitis of the wrist and finger joints in rheumatoid arthritis and to analyze the performance of FOI depending on the grade of synovitis. Twenty patients with highly active rheumatoid arthritis (mean DAS28-ESR 5.25±1.0) and thirteen healthy volunteers underwent clinical examination, FOI and contrast-enhanced 3T-MRI. Joints were rated by three independent readers semiquantitatively (grade 0-3: no, low, moderate and high grade synovitis) and compared to a semiquantitative composite standard of reference (cSOR, grade 0-3) that incorporated clinical parameters, FOI and MRI results. 2.868 evaluations in 956 joints were performed. FOI had an overall sensitivity of 57.3% and a specificity of 92.1%, whereas MRI had a sensitivity of 89.2% and a specificity of 92.6%. The sensitivity of FOI increased with the degree of synovitis to 65.0% for moderate and severe synovitis (specificity 88.1%) and 76,3% for severe synovitis (specificity 80.5%). The performance of FOI decreased with the degree of synovitis with false negative results predominantly for mild (156/343, 45.5%) and moderate (160/343, 46.6%) synovitis and false positive FOI evaluations predominantly based on weak (grade 1) signals (133/163, 81,6%). FOI has a lower sensitivity than 3T-MRI in the detection of synovitis of the hand and finger joints. The diagnostic performance of FOI decreases with the degree of synovitis and with the strength of FOI signals. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Cosmological constraints on the neutron lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Salvati, L.; Pagano, L.; Melchiorri, A. [Physics Department, Università di Roma ' ' La Sapienza' ' , Piazzale Aldo Moro 2, 00185, Rome (Italy); Consiglio, R., E-mail: laura.salvati@roma1.infn.it, E-mail: luca.pagano@roma1.infn.it, E-mail: rconsiglio@na.infn.it, E-mail: alessandro.melchiorri@roma1.infn.it [Physics Department, Università di Napoli ' ' Federico II' ' , Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)

    2016-03-01

    We derive new constraints on the neutron lifetime based on the recent Planck 2015 observations of temperature and polarization anisotropies of the CMB. Under the assumption of standard Big Bang Nucleosynthesis, we show that Planck data constrains the neutron lifetime to τ{sub n} = (907±69) [s] at 68% c.l.. Moreover, by including the direct measurements of primordial Helium abundance of Aver et al. (2015) and Izotov et al. (2014), we show that cosmological data provide the stringent constraints τ{sub n} = (875±19) [s] and τ{sub n} = (921±11) [s] respectively. The latter appears to be in tension with neutron lifetime value quoted by the Particle Data Group (τ{sub n} = (880.3±1.1) [s]). Future CMB surveys as COrE+, in combination with a weak lensing survey as EUCLID, could constrain the neutron lifetime up to a ∼ 6 [s] precision.

  8. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses the foundati......Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...

  9. Fluorescence lifetime imaging of induced pluripotent stem cells

    Science.gov (United States)

    Uchugonova, Aisada; Batista, Ana; König, Karsten

    2014-02-01

    The multiphoton FLIM tomograph MPTflex with its flexible scan head, articulated arm, and the tunable femtosecond laser source was employed to study cell monolayers and 3D cell clusters. FLIM was performed with 250 ps temporal resolution and submicron special resolution using time-correlated single photon counting. The autofluorescence based on NAD(P)H and flavins/flavoproteins has been measured in mouse embryonic fibroblasts, induced pluripotent stem cells (iPS cells) originated from mouse embryonic fibroblasts and non-proliferative mouse embryonic fibroblasts.

  10. Silica nanodisks as platforms for fluorescence lifetime-based ...

    Indian Academy of Sciences (India)

    Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India ... The nanoconjugates are found to sense the pH of the medium, through systematic ..... form pH sensing with a good level of sensitivity, with.

  11. A new front-face optical cell for measuring weak fluorescent emissions with time resolution in the picosecond time scale.

    Science.gov (United States)

    Gryczynski, Z; Bucci, E

    1993-11-01

    Recent developments of ultrafast fluorimeters allow measuring time-resolved fluorescence on the picosecond time scale. This implies one is able to monitor lifetimes and anisotropy decays of highly quenched systems and of systems that contain fluorophores having lifetimes in the subnanosecond range; both systems that emit weak signals. The combination of weak signals and very short lifetimes makes the measurements prone to distortions which are negligible in standard fluorescence experiments. To cope with these difficulties, we have designed a new optical cell for front-face optics which offers to the excitation beam a horizontal free liquid surface in the absence of interactions with optical windows. The new cell has been tested with probes of known lifetimes and anisotropies. It proved very useful in detecting tryptophan fluorescence in hemoglobin. If only diluted samples are available, which cannot be used in front-face optics, regular square geometry can still be utilized by inserting light absorbers into a cuvette of 1 cm path length.

  12. Lifetime Improvement by Battery Scheduling

    NARCIS (Netherlands)

    Jongerden, M.R.; Schmitt, Jens B.; Haverkort, Boudewijn R.H.M.

    The use of mobile devices is often limited by the lifetime of their batteries. For devices that have multiple batteries or that have the option to connect an extra battery, battery scheduling, thereby exploiting the recovery properties of the batteries, can help to extend the system lifetime. Due to

  13. Lifetime improvement by battery scheduling

    NARCIS (Netherlands)

    Jongerden, M.R.; Haverkort, Boudewijn R.H.M.

    The use of mobile devices is often limited by the lifetime of its battery. For devices that have multiple batteries or that have the option to connect an extra battery, battery scheduling, thereby exploiting the recovery properties of the batteries, can help to extend the system lifetime. Due to the

  14. Fluorescent nanoparticles for intracellular sensing: A review

    International Nuclear Information System (INIS)

    Ruedas-Rama, Maria J.; Walters, Jamie D.; Orte, Angel; Hall, Elizabeth A.H.

    2012-01-01

    Highlights: ► Analytical applications of fluorescent nanoparticles (NPs) in intracellular sensing. ► Critical review on performance of QDots, metal NPs, silica NPs, and polymer NPs. ► Highlighted potential of fluorescence lifetime imaging microscopy (FLIM). - Abstract: Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy.

  15. Fluorescent nanoparticles for intracellular sensing: A review

    Energy Technology Data Exchange (ETDEWEB)

    Ruedas-Rama, Maria J., E-mail: mjruedas@ugr.esmailto [Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Campus Cartuja, 18071, Granada (Spain); Walters, Jamie D. [Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, UK CB2 1QT (United Kingdom); Orte, Angel [Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Campus Cartuja, 18071, Granada (Spain); Hall, Elizabeth A.H., E-mail: lisa.hall@biotech.cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT (United Kingdom)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer Analytical applications of fluorescent nanoparticles (NPs) in intracellular sensing. Black-Right-Pointing-Pointer Critical review on performance of QDots, metal NPs, silica NPs, and polymer NPs. Black-Right-Pointing-Pointer Highlighted potential of fluorescence lifetime imaging microscopy (FLIM). - Abstract: Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy.

  16. Technical support document: Energy efficiency standards for consumer products: Room air conditioners, water heaters, direct heating equipment, mobile home furnaces, kitchen ranges and ovens, pool heaters, fluorescent lamp ballasts and television sets. Volume 1, Methodology

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-01

    The Energy Policy and Conservation Act (P.L. 94-163), as amended, establishes energy conservation standards for 12 of the 13 types of consumer products specifically covered by the Act. The legislation requires the Department of Energy (DOE) to consider new or amended standards for these and other types of products at specified times. DOE is currently considering amending standards for seven types of products: water heaters, direct heating equipment, mobile home furnaces, pool heaters, room air conditioners, kitchen ranges and ovens (including microwave ovens), and fluorescent light ballasts and is considering establishing standards for television sets. This Technical Support Document presents the methodology, data, and results from the analysis of the energy and economic impacts of the proposed standards. This volume presents a general description of the analytic approach, including the structure of the major models.

  17. High speed fluorescence imaging with compressed ultrafast photography

    Science.gov (United States)

    Thompson, J. V.; Mason, J. D.; Beier, H. T.; Bixler, J. N.

    2017-02-01

    Fluorescent lifetime imaging is an optical technique that facilitates imaging molecular interactions and cellular functions. Because the excited lifetime of a fluorophore is sensitive to its local microenvironment,1, 2 measurement of fluorescent lifetimes can be used to accurately detect regional changes in temperature, pH, and ion concentration. However, typical state of the art fluorescent lifetime methods are severely limited when it comes to acquisition time (on the order of seconds to minutes) and video rate imaging. Here we show that compressed ultrafast photography (CUP) can be used in conjunction with fluorescent lifetime imaging to overcome these acquisition rate limitations. Frame rates up to one hundred billion frames per second have been demonstrated with compressed ultrafast photography using a streak camera.3 These rates are achieved by encoding time in the spatial direction with a pseudo-random binary pattern. The time domain information is then reconstructed using a compressed sensing algorithm, resulting in a cube of data (x,y,t) for each readout image. Thus, application of compressed ultrafast photography will allow us to acquire an entire fluorescent lifetime image with a single laser pulse. Using a streak camera with a high-speed CMOS camera, acquisition rates of 100 frames per second can be achieved, which will significantly enhance our ability to quantitatively measure complex biological events with high spatial and temporal resolution. In particular, we will demonstrate the ability of this technique to do single-shot fluorescent lifetime imaging of cells and microspheres.

  18. Lifetime costs of cerebral palsy

    DEFF Research Database (Denmark)

    Kruse, Marie; Michelsen, Susan Ishøy; Flachs, Esben Meulengracht

    2009-01-01

    This study quantified the lifetime costs of cerebral palsy (CP) in a register-based setting. It was the first study outside the US to assess the lifetime costs of CP. The lifetime costs attributable to CP were divided into three categories: health care costs, productivity costs, and social costs....... social care costs and productivity costs associated with CP point to a potential gain from labour market interventions that benefit individuals with CP.......This study quantified the lifetime costs of cerebral palsy (CP) in a register-based setting. It was the first study outside the US to assess the lifetime costs of CP. The lifetime costs attributable to CP were divided into three categories: health care costs, productivity costs, and social costs...... in 2000. The prevalence of CP in eastern Denmark was approximately 1.7 per 1000. Information on productivity and the use of health care was retrieved from registers. The lifetime cost of CP was about euro860 000 for men and about euro800 000 for women. The largest component was social care costs...

  19. Lifetime measurement of trapped staus using ATLAS

    CERN Document Server

    Sibley, Logan

    I study the creation of long-lived staus at a 14 TeV centre of mass energy in proton-proton collisions at the LHC using both the ATLAS and ACME detectors. The ATLAS overburden or underburden, or even ATLAS itself, may trap the semi-stable staus at that place where they will remain until the time at which they decay, where the stau lifetime ranges between seven days and one year. Using a novel method, one may count the number of muons and pions originating from the stau decay using the standard ATLAS cosmic ray trigger. Using an idealized detector model, I find that this method can lead to measurements of the stau lifetime and SUSY cross-section to within statistical uncertainties of 6% and 1% of their actual values, respectively.

  20. New parameters influencing hydraulic runner lifetime

    International Nuclear Information System (INIS)

    Sabourin, M; Bouffard, D A; Thibault, D; Levesque, M

    2010-01-01

    Traditionally, hydraulic runner mechanical design is based on calculation of static stresses. Today, validation of hydraulic runner design in terms of reliability requires taking into account the fatigue effect of dynamics loads. A damage tolerant approach based on fracture mechanics is the method chosen by Alstom and Hydro-Quebec to study fatigue damage in runners. This requires a careful examination of all factors influencing material fatigue behavior. Such material behavior depends mainly on the chemical composition, microstructure and thermal history of the component, and on the resulting residual stresses. Measurement of fracture mechanics properties of various steels have demonstrated that runner lifetime can be significantly altered by differences in the manufacturing process, although remaining in accordance with agreed practices and standards such as ASTM. Carbon content and heat treatment are suspected to influence fatigue lifetime. This will have to be investigated by continuing the current research.

  1. New parameters influencing hydraulic runner lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Sabourin, M; Bouffard, D A [Alstom Hydro Canada Inc, Hydraulic Engineering, 1350 chemin St-Roch, Sorel-Tracy (Quebec), J3P 5P9 (Canada); Thibault, D [Hydro-Quebec, Institut de Recherche d' Hydro-Quebec 1800 boul. Lionel-Boulet, Varennes (Quebec), J3X 1S1 (Canada); Levesque, M, E-mail: michel.sabourin@power.alstom.co [Ecole Polytechnique de Montreal, Departement de genie mecanique C.P.6079, succ. Centre-ville, Montreal (Quebec), H3C 3A7 (Canada)

    2010-08-15

    Traditionally, hydraulic runner mechanical design is based on calculation of static stresses. Today, validation of hydraulic runner design in terms of reliability requires taking into account the fatigue effect of dynamics loads. A damage tolerant approach based on fracture mechanics is the method chosen by Alstom and Hydro-Quebec to study fatigue damage in runners. This requires a careful examination of all factors influencing material fatigue behavior. Such material behavior depends mainly on the chemical composition, microstructure and thermal history of the component, and on the resulting residual stresses. Measurement of fracture mechanics properties of various steels have demonstrated that runner lifetime can be significantly altered by differences in the manufacturing process, although remaining in accordance with agreed practices and standards such as ASTM. Carbon content and heat treatment are suspected to influence fatigue lifetime. This will have to be investigated by continuing the current research.

  2. Polar plot representation of time-resolved fluorescence.

    Science.gov (United States)

    Eichorst, John Paul; Wen Teng, Kai; Clegg, Robert M

    2014-01-01

    Measuring changes in a molecule's fluorescence emission is a common technique to study complex biological systems such as cells and tissues. Although the steady-state fluorescence intensity is frequently used, measuring the average amount of time that a molecule spends in the excited state (the fluorescence lifetime) reveals more detailed information about its local environment. The lifetime is measured in the time domain by detecting directly the decay of fluorescence following excitation by short pulse of light. The lifetime can also be measured in the frequency domain by recording the phase and amplitude of oscillation in the emitted fluorescence of the sample in response to repetitively modulated excitation light. In either the time or frequency domain, the analysis of data to extract lifetimes can be computationally intensive. For example, a variety of iterative fitting algorithms already exist to determine lifetimes from samples that contain multiple fluorescing species. However, recently a method of analysis referred to as the polar plot (or phasor plot) is a graphical tool that projects the time-dependent features of the sample's fluorescence in either the time or frequency domain into the Cartesian plane to characterize the sample's lifetime. The coordinate transformations of the polar plot require only the raw data, and hence, there are no uncertainties from extensive corrections or time-consuming fitting in this analysis. In this chapter, the history and mathematical background of the polar plot will be presented along with examples that highlight how it can be used in both cuvette-based and imaging applications.

  3. Multiphoton autofluorescence lifetime imaging of induced pluripotent stem cells

    Science.gov (United States)

    Uchugonova, Aisada

    2017-06-01

    The multiphoton fluorescence lifetime imaging tomograph MPTflex with its flexible 360-deg scan head, articulated arm, and tunable femtosecond laser source was employed to study induced pluripotent stem cell (iPS) cultures. Autofluorescence (AF) lifetime imaging was performed with 250-ps temporal resolution and submicron spatial resolution using time-correlated single-photon counting. The two-photon excited AF was based on the metabolic coenzymes NAD(P)H and flavin adenine dinucleotide/flavoproteins. iPS cells generated from mouse embryonic fibroblasts (MEFs) and cocultured with growth-arrested MEFs as feeder cells have been studied. Significant differences on AF lifetime signatures were identified between iPS and feeder cells as well as between their differentiating counterparts.

  4. A lifetime prediction method for LEDs considering mission profiles

    DEFF Research Database (Denmark)

    Qu, Xiaohui; Wang, Huai; Zhan, Xiaoqing

    2016-01-01

    and to benchmark the cost-competitiveness of different lighting technologies. The existing lifetime data released by LED manufacturers or standard organizations are usually applicable only for specific temperature and current levels. Significant lifetime discrepancies may be observed in field operations due...... to the varying operational and environmental conditions during the entire service time (i.e., mission profiles). To overcome the challenge, this paper proposes an advanced lifetime prediction method, which takes into account the field operation mission profiles and the statistical properties of the life data...

  5. Characterization of porcine eyes based on autofluorescence lifetime imaging

    Science.gov (United States)

    Batista, Ana; Breunig, Hans Georg; Uchugonova, Aisada; Morgado, António Miguel; König, Karsten

    2015-03-01

    Multiphoton microscopy is a non-invasive imaging technique with ideal characteristics for biological applications. In this study, we propose to characterize three major structures of the porcine eye, the cornea, crystalline lens, and retina using two-photon excitation fluorescence lifetime imaging microscopy (2PE-FLIM). Samples were imaged using a laser-scanning microscope, consisting of a broadband sub-15 femtosecond (fs) near-infrared laser. Signal detection was performed using a 16-channel photomultiplier tube (PMT) detector (PML-16PMT). Therefore, spectral analysis of the fluorescence lifetime data was possible. To ensure a correct spectral analysis of the autofluorescence lifetime data, the spectra of the individual endogenous fluorophores were acquired with the 16-channel PMT and with a spectrometer. All experiments were performed within 12h of the porcine eye enucleation. We were able to image the cornea, crystalline lens, and retina at multiple depths. Discrimination of each structure based on their autofluorescence intensity and lifetimes was possible. Furthermore, discrimination between different layers of the same structure was also possible. To the best of our knowledge, this was the first time that 2PE-FLIM was used for porcine lens imaging and layer discrimination. With this study we further demonstrated the feasibility of 2PE-FLIM to image and differentiate three of the main components of the eye and its potential as an ophthalmologic technique.

  6. Measurement of Charm Meson Lifetimes

    International Nuclear Information System (INIS)

    Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L.P.; Zhou, G.J.; Chan, S.; Eigen, G.; Lipeles, E.; Schmidtler, M.; Shapiro, A.; Sun, W.M.; Urheim, J.; Weinstein, A.J.; Wuerthwein, F.; Jaffe, D.E.; Masek, G.; Paar, H.P.; Potter, E.M.; Prell, S.; Sharma, V.; Asner, D.M.; Eppich, A.; Gronberg, J.; Hill, T.S.; Korte, C.M.; Lange, D.J.; Morrison, R.J.; Nelson, H.N.; Nelson, T.K.; Roberts, D.; Tajima, H.; Behrens, B.H.; Ford, W.T.; Gritsan, A.; Krieg, H.; Roy, J.; Smith, J.G.; Alexander, J.P.; Baker, R.; Bebek, C.; Berger, B.E.; Berkelman, K.; Boisvert, V.; Cassel, D.G.; Crowcroft, D.S.; Dickson, M.; Dombrowski, S. von; Drell, P.S.; Dumas, D.J.; Ecklund, K.M.; Ehrlich, R.; Foland, A.D.; Gaidarev, P.; Gibbons, L.; Gittelman, B.; Gray, S.W.; Hartill, D.L.; Heltsley, B.K.; Henderson, S.; Hopman, P.I.; Katayama, N.; Kreinick, D.L.; Lee, T.; Liu, Y.; Meyer, T.O.; Mistry, N.B.; Ng, C.R.; Nordberg, E.; Ogg, M.; Patterson, J.R.; Peterson, D.; Riley, D.; Soffer, A.; Thayer, J.G.; Thies, P.G.; Valant-Spaight, B.; Warburton, A.; Ward, C.; Athanas, M.; Avery, P.; Jones, C.D.; Lohner, M.; Prescott, C.; Rubiera, A.I.; Yelton, J.; Zheng, J.; Brandenburg, G.; Briere, R.A.; Ershov, A.; Gao, Y.S.; Kim, D.Y.; Wilson, R.; Browder, T.E.; Li, Y.; Rodriguez, J.L.; Yamamoto, H.; Bergfeld, T.; Eisenstein, B.I.; Ernst, J.; Gladding, G.E.; Gollin, G.D

    1999-01-01

    We report measurements of the D 0 , D + , and D + s meson lifetimes using 3.7 fb -1 of e + e - annihilation data collected near the Υ(4S) resonance with the CLEO detector. The measured lifetimes of the D 0 , D + , and D + s mesons are 408.5±4.1 +3.5 -3.4 fs , 1033.6±22.1 +9.9 -12.7 fs , and 486.3±15.0 +4.9 -5.1 fs . The precision of these lifetimes are comparable to those of the best previous measurements, and the systematic errors are very different. In a single experiment we find that the ratio of the D + s and D 0 lifetimes is 1.19±0.04 . copyright 1999 The American Physical Society

  7. Deconvolution of Positrons' Lifetime spectra

    International Nuclear Information System (INIS)

    Calderin Hidalgo, L.; Ortega Villafuerte, Y.

    1996-01-01

    In this paper, we explain the iterative method previously develop for the deconvolution of Doppler broadening spectra using the mathematical optimization theory. Also, we start the adaptation and application of this method to the deconvolution of positrons' lifetime annihilation spectra

  8. Anthracene Fluorescence Quenching by a Tetrakis (Ketocarboxamide Cavitand

    Directory of Open Access Journals (Sweden)

    Tibor Zoltan Janosi

    2014-01-01

    Full Text Available Quenching of both fluorescence lifetime and fluorescence intensity of anthracene was investigated in the presence of a newly derived tetrakis (ketocarboxamide cavitand at various concentrations. Time-correlated single photon counting method was applied for the lifetime measurements. A clear correlation between the fluorescence lifetime of anthracene as a function of cavitand concentration in dimethylformamide solution was observed. The bimolecular collisional quenching constant was derived from the decrease of lifetime. Fluorescence intensity was measured in the emission wavelength region around 400 nm as a result of excitation at 280 nm. Effective quenching was observed in the presence of the cavitand. The obtained Stern-Volmer plot displayed upward curvature. The results did not follow even extended Stern-Volmer behavior, often used to describe deviations from static bimolecular quenching. To explain our results we adopted the Smoluchowski model and obtained a reasonable estimate for the molecular radius of the cavitand in solution.

  9. The fluorescence behaviour of methyl and phenyl salicylate

    Science.gov (United States)

    Ford, D.; Thistlethwaite, P. J.; Woolfe, G. J.

    1980-01-01

    Fluorcsccnce lifetimes tor the 450 nm emission of methyl and phenyl salicylate in various solvents have been measured. Qucnching studics on the 340 nm fluorescence of these molecules point to the existence of three distinct ground state conformers.

  10. Introduction to fluorescence

    CERN Document Server

    Jameson, David M

    2014-01-01

    "An essential contribution to educating scientists in the principles of fluorescence. It will also be an important addition to the libraries of practitioners applying the principles of molecular fluorescence."-Ken Jacobson, Kenan Distinguished Professor of Cell Biology and Physiology, University of North Carolina at Chapel Hill"An exquisite compendium of fluorescence and its applications in biochemistry enriched by a very exciting historical perspective. This book will become a standard text for graduate students and other scientists."-Drs. Zygmunt (Karol) Gryczynski and Ignacy Gryczynski, University of North Texas Health Science Center"… truly a masterwork, combining clarity, precision, and good humor. The reader, novice or expert, will be pleased with the text and will not stop reading. It is a formidable account of the fluorescence field, which has impacted the life sciences so considerably in the last 60 years."-Jerson L. Silva, M.D., Ph.D., Professor and Director, National Institute of Science and Tech...

  11. Effects of short term changes in the blood glucose level on the autofluorescence lifetime of the human retina in healthy volunteers

    Science.gov (United States)

    Klemm, Matthias; Nagel, Edgar; Schweitzer, Dietrich; Schramm, Stefan; Haueisen, Jens

    2016-03-01

    Purpose: Fluorescence lifetime imaging ophthalmoscopy (FLIO) provides in vivo metabolic mapping of the ocular fundus. Changes in FLIO have been found in e.g. diabetes patients. The influence of short term metabolic changes caused by blood glucose level changes on is unknown. Aim of this work is the detection of short-term changes in fundus autofluorescence lifetime during an oral glucose tolerance test. Methods: FLIO was performed in 10 healthy volunteers (29+/-4 years, fasting for 12h) using a scanning laser ophthalmoscope (30° fundus, 34μm resolution, excitation with 473nm diode laser with 70 ps pulses at 80 MHz repetition rate, detection in two spectral channels 500-560nm (ch1) and 560-720nm (ch2) using the timecorrelated single photon counting method). The blood glucose level (BGL) was measured by an Accu-Chek® Aviva self-monitoring device. Before and after a glucose drink (300ml solution, containing 75g of glucose (Accu-Chek® Dextrose O.G.T.), BGL and FLIO were measured every 15min. The FLIMX software package was applied to compute the average fluorescence lifetime τ on the inner ring of the ETDRS grid using a modified 3-exponential approach. Results: The results are given as mean +/- standard deviation over all volunteers in ch1. Baseline measurement: BGL: 5.3+/-0.4 mmol/l, τ1: 49+/-6ps. A significant reduction (α=5% Wilcoxon rank-sum test) in τ1 is detected after 15min (BGL: 8.4+/-1.1 mmol/l, τ1: 44+/-5ps) and after 90min (BGL: 6.3+/-1.4 mmol/l, τ1: 41+/-5ps). Results of ch2 show smaller reductions in the fluorescence lifetimes over time.

  12. Fluorescence resonance energy transfer imaging of CFP/YFP labeled NDH in cyanobacterium cell

    International Nuclear Information System (INIS)

    Ji Dongmei; Lv Wei; Huang Zhengxi; Xia Andong; Xu Min; Ma Weimin; Mi Hualing; Ogawa Teruo

    2007-01-01

    The laser confocal scanning microscopy combined with time-correlated single photon counting imaging technique to obtain fluorescence intensity and fluorescence lifetime images for fluorescence resonance energy transfer measurement is reported. Both the fluorescence lifetime imaging microscopy (FLIM) and intensity images show inhomogeneous cyan fluorescent protein and yellow fluorescent protein (CFP /YFP) expression or inhomogeneous energy transfer between CFP and YFP over whole cell. The results presented in this work show that FLIM could be a potential method to reveal the structure-function behavior of NAD(P)H dehydrogenase complexes in living cell

  13. Final report on reliability and lifetime prediction.

    Energy Technology Data Exchange (ETDEWEB)

    Gillen, Kenneth T; Wise, Jonathan; Jones, Gary D.; Causa, Al G.; Terrill, Edward R.; Borowczak, Marc

    2012-12-01

    This document highlights the important results obtained from the subtask of the Goodyear CRADA devoted to better understanding reliability of tires and to developing better lifetime prediction methods. The overall objective was to establish the chemical and physical basis for the degradation of tires using standard as well as unique models and experimental techniques. Of particular interest was the potential application of our unique modulus profiling apparatus for assessing tire properties and for following tire degradation. During the course of this complex investigation, extensive relevant information was generated, including experimental results, data analyses and development of models and instruments. Detailed descriptions of the findings are included in this report.

  14. Occupational risk and lifetime exposure

    International Nuclear Information System (INIS)

    Lapp, R.E.

    1991-01-01

    Any lowering of annual radiation limits for occupational exposure should be based on industry experience with lifetime doses and not on a worst case career exposure of 47 years. Two decades of experience show a lifetime accumulation of less than 1.5 rem for workers with measurable exposure. This is 5% of the normal lifetime exposure of Americans to natural and medical radiation. Any epidemiology of the US nuclear power workforce's two decade long exposure would have to focus on excess leukemia. Application of the Hiroshima and Nagasaki cancer mortality shows that too few leukemias would be expressed to permit a feasible epidemiology. Ionizing radiation appears to be a mild carcinogen as compared to physical and chemical agents presented in the occupational environment. A realistic factor in determining any change in occupational exposure limits for ionizing radiation should take into account the past performance of the licensee and potential health effects applicable to the workplace. Specifically, the lifetime exposure data for workers at nuclear power plants and naval shipyards should be considered. The nuclear industry and the US Navy have detailed data on the annual exposure of workers with a combined collective exposure approaching 1 million worker-rem. The lifetime dose for naval personnel and shipyard workers averages 1.1 rem J 1990. Shipyard workers have an annual dose of 0.28 rem per work-year and a mean exposure time of 4.4 years. The data apply to workers with measurable dose

  15. Confocal fluorescence techniques in industrial application

    Science.gov (United States)

    Eggeling, Christian; Gall, Karsten; Palo, Kaupo; Kask, Peet; Brand, Leif

    2003-06-01

    The FCS+plus family of evaluation tools for confocal fluorescence spectroscopy, which was developed during recent years, offers a comprehensive view to a series of fluorescence properties. Originating in fluorescence correlation spectroscopy (FCS) and using similar experimental equipment, a system of signal processing methods such as fluorescence intensity distribution analysis (FIDA) was created to analyze in detail the fluctuation behavior of fluorescent particles within a small area of detection. Giving simultaneous access to molecular parameters like concentration, translational and rotational diffusion, molecular brightness, and multicolor coincidence, this portfolio was enhanced by more traditional techniques of fluorescence lifetime as well as time-resolved anisotropy determination. The cornerstones of the FCS+plus methodology will be shortly described. The inhibition of a phosphatase enzyme activity gives a comprehensive industrial application that demonstrates FCS+plus' versatility and its potential for pharmaceutical drug discovery.

  16. STANDARDIZATION OF A FLUORESCENT-BASED QUANTITATIVE ADHESION ASSAY TO STUDY ATTACHMENT OF Taenia solium ONCOSPHERE TO EPITHELIAL CELLS In Vitro

    Science.gov (United States)

    Chile, Nancy; Evangelista, Julio; Gilman, Robert H.; Arana, Yanina; Palma, Sandra; Sterling, Charles R; Garcia, Hector H.; Gonzalez, Armando; Verastegui, Manuela

    2012-01-01

    To fully understand the preliminary stages of Taenia solium oncosphere attachment in the gut, adequate tools and assays are necessary to observe and quantify this event that leads to infection. A fluorescent-based quantitative adhesion assay, using biotinylated activated-oncospheres and monolayers of Chinese hamster ovary cells (CHO-K1) or human intestinal monolayer cells (INT-407, HCT-8 or HT-29), was developed to study initial events during the infection of target cells and to rapidly quantify the in vitro adhesion of T. solium oncospheres. Fluorescein streptavidin was used to identify biotinylated activated-oncospheres adhered to cells. This adherence was quantified using an automated fluorescence plate reader, and the results were expressed as fluorescence intensity values. A series of three assays were performed. The first was to identify the optimum number of biotinylated activated-oncospheres to be used in the adhesion assay. The goal of the second assay was to validate this novel method with the established oncosphere-binding system using the immunofluorescent-antibody assay (IFA) method to quantify oncosphere adhesion. A total of 10,000 biotinylated activated-oncospheres were utilized to assess the role of sera and laminin (LM) in oncosphere adherence to a CHO-K1 cell monolayer. The findings that sera and LM increase the adhesion of oncospheres to monolayer cells were similar to results that were previously obtained using the IFA method. The third assay compared the adherence of biotinylated activated-oncospheres to different types of human intestinal monolayer cells. In this case, the fluorescence intensity was greatest when using the INT-407 cell monolayer. We believe this new method of quantification offers the potential for rapid, large-scale screening to study and elucidate specific molecules and mechanisms involved in oncosphere-host cell attachment. PMID:22178422

  17. Recoil distance lifetime measurements in 122,124Xe

    Science.gov (United States)

    Govil, I. M.; Kumar, A.; Iyer, H.; Li, H.; Garg, U.; Ghugre, S. S.; Johnson, T.; Kaczarowski, R.; Kharraja, B.; Naguleswaran, S.; Walpe, J. C.

    1998-02-01

    Lifetimes of the lower-excited states in 122,124Xe are measured using the recoil-distance Doppler-shift technique. The reactions 110Pd(16O,4n)122Xe and 110Pd(18O,4n)124Xe at a beam energy of 66 MeV were used for this experiment. The lifetimes of the 2+, 4+, 6+, and 8+ states of the ground state band were extracted using the computer code LIFETIME including the corrections due to the side feeding and the nuclear deorientation effects. The lifetime of the 2+ state in 122Xe agrees with the recoil distance method (RDM) measurements but for the 124Xe it does not agree with the RDM measurements but agrees with the Coulomb-excitation experiment. The measured B(E2) values for both the nuclei are compared with the standard algebraic and the multishell models.

  18. Plasmonic enhancement of ultraviolet fluorescence

    Science.gov (United States)

    Jiao, Xiaojin

    Plasmonics relates to the interaction between electromagnetic radiation and conduction electrons at metallic interfaces or in metallic nanostructures. Surface plasmons are collective electron oscillations at a metal surface, which can be manipulated by shape, texture and material composition. Plasmonic applications cover a broad spectrum from visible to near infrared, including biosensing, nanolithography, spectroscopy, optoelectronics, photovoltaics and so on. However, there remains a gap in this activity in the ultraviolet (UV, research. Motivating factors in the study of UV Plasmonics are the direct access to biomolecular resonances and native fluorescence, resonant Raman scattering interactions, and the potential for exerting control over photochemical reactions. This dissertation aims to fill in the gap of Plasmonics in the UV with efforts of design, fabrication and characterization of aluminium (Al) and magnesium (Mg) nanostructures for the application of label-free bimolecular detection via native UV fluorescence. The first contribution of this dissertation addresses the design of Al nanostructures in the context of UV fluorescence enhancement. A design method that combines analytical analysis with numerical simulation has been developed. Performance of three canonical plasmonic structures---the dipole antenna, bullseye nanoaperture and nanoaperture array---has been compared. The optimal geometrical parameters have been determined. A novel design of a compound bullseye structure has been proposed and numerically analyzed for the purpose of compensating for the large Stokes shift typical of UV fluorescence. Second, UV lifetime modification of diffusing molecules by Al nanoapertures has been experimentally demonstrated for the first time. Lifetime reductions of ~3.5x have been observed for the high quantum yield (QY) laser dye p-terphenyl in a 60 nm diameter aperture with 50 nm undercut. Furthermore, quantum-yield-dependence of lifetime reduction has been

  19. Lifetime results from heavy quark systems

    International Nuclear Information System (INIS)

    Papadimitriou, V.

    1997-11-01

    We present the latest measurements of weakly decaying b-hadrons from experiments at e + e - and p anti p colliders. These measurements include the average lifetime of b-hadrons, lifetimes of the B - , B 0 and B 0 s mesons, the average lifetime of b-baryons and lifetimes of the Λ b and Ξ b baryons

  20. Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media

    Science.gov (United States)

    Cerussi, Albert Edward

    1999-09-01

    In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of

  1. Fluorescent Nanodiamonds in Biomedical Applications.

    Science.gov (United States)

    Mitura, Katarzyna Anna; Włodarczyk, Elżbieta

    2018-04-18

    Nanoparticles have an extended surface and a large surface area, which is the ratio of the size of the surfacearea to the volume. A functionalized surface can give rise to more modifications and therefore allows this nanomaterial to have new properties. Fluorescent molecules contain fluorophore, which is capable of being excited via the absorption of light energy at a specific wavelength and subsequently emitting radiation energy of a longer wavelength. A chemically modified surface of nanodiamond (ND; by carboxylation) demonstrated biocompatibility with DNA, cytochrome C, and antigens. In turn, fluorescent nanodiamonds (FNDs) belong to a group of new nanomaterials. Their surface can be modified by joining functional groups such as carboxyl, hydroxyl, or amino, after which they can be employed as a fluorescence agent. Their fluorescent properties result from defects in the crystal lattice. FNDs reach dimensions of 4-100 nm, have attributes such as photostability, long fluorescence lifetimes (10 ns), and fluorescence emission between 600 and 700 nm. They are also nontoxic, chemically inert, biocompatible, and environmentally harmless. The main purpose of this article was to present the medical applications of various types of modified NDs.

  2. Reactor pressure vessel embrittlement of NPP borssele: Design lifetime and lifetime extension

    International Nuclear Information System (INIS)

    Blom, F.J.

    2007-01-01

    Embrittlement of the reactor pressure vessel of the Borssele nuclear power plant has been investigated taking account of the design lifetime of 40 years and considering 20 years subsequent lifetime extension. The paper presents the current licensing status based on considerations of material test data and of US nuclear regulatory standards. Embrittlement status is also evaluated against German and French nuclear safety standards. Results from previous fracture toughness and Charpy tests are investigated by means of the Master curve toughness transition approach. Finally, state of the art insights are investigated by means of literature research. Regarding the embrittlement status of the reactor pressure vessel of Borssele nuclear power plant it is concluded that there is a profound basis for the current license up to the original end of the design life in 2013. The embrittlement temperature changes only slightly with respect to the acceptance criterion adopted postulating further operation up to 2033. Continued safe operation and further lifetime extension are therefore not restricted by reactor pressure vessel embrittlement

  3. Lifetime value in business process

    Directory of Open Access Journals (Sweden)

    Martin Souček

    2011-01-01

    Full Text Available The paper focuses on lifetime value assessment and its implementation and application in business processes. The lifetime value is closely connected to customer relationship management. The paper presents results of three consecutive researches devoted to issues of customer relationship management. The first two from 2008 and 2010 were conducted as quantitative ones; the one from 2009 had qualitative nature. The respondents were representatives of particular companies. The means for data collection was provided by ReLa system. We will focus on individual attributes of lifetime value of a customer, and relate them to approaches of authors mentioned in introduction. Based on the qualitative research data, the paper focuses on individual customer lifetime value parameters. These parameters include: the cost to the customer relationship acquisition and maintenance, profit generated from a particular customer, customer awareness value, the level of preparedness to adopt new products, the value of references and customer loyalty level. For each of these parameters, the paper provides specific recommendations. Moreover, it is possible to learn about the nature of these parameter assessments in the Czech environment.

  4. Lifetime of heavy flavour particles

    International Nuclear Information System (INIS)

    Lueth, V.

    1985-10-01

    Recent measurements of the lifetime of the tau leptons and charm and beauty hadrons are reviewed and their significance for the couplings of the charged weak current, flavour mixing, and models relating quarks to hadron decay are discussed. 70 refs., 17 figs., 5 tabs

  5. Fluorescence Decay Dynamics of Ethidium Bromide in Polymers

    International Nuclear Information System (INIS)

    Jee, Ah Young; Min Yung

    2010-01-01

    The fluorescence lifetimes of EB in five polymers covering LDPE, HDPE, PC, PS, and PAA were measured by picosecond time-correlated single photon counting. The lifetime change of EB has been previously described by hydrogen bonding ability. In this work, we have observed that the lifetime of EB depends strongly on the Young's modulus of medium. Thus, it is possible that the fluorescence decay dynamics of EB could be influenced by medium rigidity rather than hydrogen bonding ability in polymer. The medium influence on the fluorescence decay dynamics of ethidium bromide (EB) has been investigated in various environments. For example, Ohmstead and Kearns related the fluorescence lifetime of EB to the excited-state proton transfer process. In addition, they reported that the solvent viscosity plays a minor role in the excited state decay process of EB. Chirico et al. measured the fluorescence decay of EB as 1.7 ns in water and 6.5 ns in ethanol and concluded that hydrogen bonding ability is a key factor for the nonradiative relaxation. Pal et al. measured the fluorescence decay time of EB in acetone, acetonitrile, and their mixtures. They observed that the fluorescence decay processes were independent on the solvent polarity. These results show that the EB lifetime does not depend much on polarity or viscosity, but is mainly influenced by hydrogen bonding. Overall, EB is one of most widely used dyes for probing DNA. When EB is intercalated into the helical structure of DNA, a large increase in the fluorescence lifetime has been observed in comparison with water environment, and the fluorescence enhancement was attributed to the blocking of the excited-state proton transfer

  6. Heritability of lifetime ecstasy use.

    Science.gov (United States)

    Verweij, Karin J H; Treur, Jorien L; Vreeker, Annabel; Brunt, Tibor M; Willemsen, Gonneke; Boomsma, Dorret I; Vink, Jacqueline M

    2017-09-01

    Ecstasy is a widely used psychoactive drug that users often take because they experience positive effects such as increased euphoria, sociability, elevated mood, and heightened sensations. Ecstasy use is not harmless and several immediate and long term side effects have been identified. Lifetime ecstasy use is likely to be partly influenced by genetic factors, but no twin study has determined the heritability. Here, we apply a classical twin design to a large sample of twins and siblings to estimate the heritability of lifetime ecstasy use. The sample comprised 8500 twins and siblings aged between 18 and 45 years from 5402 families registered at the Netherlands Twin Registry. In 2013-2014 participants filled out a questionnaire including a question whether they had ever used ecstasy. We used the classical twin design to partition the individual differences in liability to ecstasy use into that due to genetic, shared environmental, and residual components. Overall, 10.4% of the sample had used ecstasy during their lifetime, with a somewhat higher prevalence in males than females. Twin modelling indicated that individual differences in liability to lifetime ecstasy use are for 74% due to genetic differences between individuals, whereas shared environmental and residual factors explain a small proportion of its liability (5% and 21%, respectively). Although heritability estimates appeared to be higher for females than males, this difference was not significant. Lifetime ecstasy use is a highly heritable trait, which indicates that some people are genetically more vulnerable to start using ecstasy than others. Copyright © 2017. Published by Elsevier B.V.

  7. Exits in order: How crowding affects particle lifetimes

    Energy Technology Data Exchange (ETDEWEB)

    Penington, Catherine J.; Simpson, Matthew J. [School of Mathematical Sciences, Queensland University of Technology, Brisbane (Australia); Baker, Ruth E. [Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford (United Kingdom)

    2016-06-28

    Diffusive processes are often represented using stochastic random walk frameworks. The amount of time taken for an individual in a random walk to intersect with an absorbing boundary is a fundamental property that is often referred to as the particle lifetime, or the first passage time. The mean lifetime of particles in a random walk model of diffusion is related to the amount of time required for the diffusive process to reach a steady state. Mathematical analysis describing the mean lifetime of particles in a standard model of diffusion without crowding is well known. However, the lifetime of agents in a random walk with crowding has received much less attention. Since many applications of diffusion in biology and biophysics include crowding effects, here we study a discrete model of diffusion that incorporates crowding. Using simulations, we show that crowding has a dramatic effect on agent lifetimes, and we derive an approximate expression for the mean agent lifetime that includes crowding effects. Our expression matches simulation results very well, and highlights the importance of crowding effects that are sometimes overlooked.

  8. Study on the fluorescence characteristics of carbon dots

    Science.gov (United States)

    Mao, Xiao-Jiao; Zheng, Hu-Zhi; Long, Yi-Juan; Du, Juan; Hao, Jian-Yu; Wang, Ling-Ling; Zhou, Dong-Bo

    2010-02-01

    Herein, we prepared water-soluble fluorescent carbon dots with diameter about 1.5 nm from cheap commercial lampblack. These fluorescent carbon nanoparticles are stable toward photobleaching and stable in water for more than half a year without fluorescence decrease. In order to improve its fluorescence properties, we passivated these nanoparticles with bisamino-terminated polyethylene glycol (PEG 1500N). Therefore, both fluorescence quantum yield and lifetime increased after this progress. In addition, the passivated carbon dots were more inert to solvent than the bare one and showed different responses to pH change.

  9. Riboflavin enhanced fluorescence of highly reduced graphene oxide

    Science.gov (United States)

    Iliut, Maria; Gabudean, Ana-Maria; Leordean, Cosmin; Simon, Timea; Teodorescu, Cristian-Mihail; Astilean, Simion

    2013-10-01

    The improvement of graphene derivates' fluorescence properties is a challenging topic and very few ways were reported up to now. In this Letter we propose an easy method to enhance the fluorescence of highly reduced graphene oxide (rGO) through non-covalent binding to a molecular fluorophore, namely the riboflavin (Rb). While the fluorescence of Rb is quenched, the Rb - decorated rGO exhibits strong blue fluorescence and significantly increased fluorescence lifetime, as compared to its pristine form. The data reported here represent a promising start towards tailoring the optical properties of rGOs, having utmost importance in optical applications.

  10. Dual fluorescence of single LH2 antenna nanorings

    International Nuclear Information System (INIS)

    Freiberg, A.; Raetsep, M.; Timpmann, K.; Trinkunas, G.

    2004-01-01

    A dual nature of fluorescence from LH2 pigment-protein complexes, which is a part of the light harvesting system of purple bacteria, is confirmed by fluorescence-lifetime dependence on recording wavelength and spectrally selective spectroscopy. An analysis based on the Holstein molecular crystal model, modified by allowing diagonal disorder, suggests coexistence of large- and small-radius self-trapped excitons, which serve as the origin of the dual fluorescence

  11. Emerging biomedical applications of time-resolved fluorescence spectroscopy

    Science.gov (United States)

    Lakowicz, Joseph R.; Szmacinski, Henryk; Koen, Peter A.

    1994-07-01

    Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics, and chemical physics. Advances in laser technology, the development of long-wavelength probes, and the use of lifetime-based methods are resulting in the rapid migration of time-resolved fluorescence to the clinical chemistry lab, to the patient's bedside, to flow cytometers, to the doctor's office, and even to home health care. Additionally, time-resolved imaging is now a reality in fluorescence microscopy, and will provide chemical imaging of a variety of intracellular analytes and/or cellular phenomena. In this overview paper we attempt to describe some of the opportunities available using chemical sensing based on fluorescence lifetimes, and to predict those applications of lifetime-based sensing which are most likely in the near future.

  12. A measurement of the neutron lifetime by counting trapped protons

    CERN Document Server

    Snow, W M; Dewey, M S; Fei, X; Gilliam, D M; Greene, G L; Nico, J S; Wietfeldt, F E

    2000-01-01

    A measurement of the neutron lifetime tau sub n performed by trapping and counting decay protons from in-beam neutron decays in a Penning trap is in progress at the National Institute of Standards and Technology (NIST). A description of the measurement technique, the status of the data analysis, and prospects for improvements in the measurement are discussed.

  13. Projected Lifetime Healthcare Costs Associated with HIV Infection

    DEFF Research Database (Denmark)

    Nakagawa, Fumiyo; Miners, Alec; Smith, Colette J

    2015-01-01

    computer simulation model to project the distribution of lifetime outcomes and costs of men-who-have-sex-with-men (MSM) infected with HIV in 2013 aged 30, over 10,000 simulations. We assumed a resource-rich setting with no loss to follow-up, and that standards and costs of healthcare management remain...

  14. Lifetime of a black hole

    International Nuclear Information System (INIS)

    Carlitz, R.D.; Willey, R.S.

    1987-01-01

    We study the constraints placed by quantum mechanics upon the lifetime of a black hole. In the context of a moving-mirror analog model for the Hawking radiation process, we conclude that the period of Hawking radiation must be followed by a much longer period during which the remnant mass (of order m/sub P/) may be radiated away. We are able to place a lower bound on the time required for this radiation process, which translates into a lower bound for the lifetime of the black hole. Particles which are emitted during the decay of the remnant, like the particles which comprise the Hawking flux, may be uncorrelated with each other. But each particle emitted from the decaying remnant is correlated with one particle emitted as Hawking radiation. The state which results after the remnant has evaporated is one which locally appears to be thermal, but which on a much larger scale is marked by extensive correlations

  15. Luminosity lifetime in the Tevatron

    International Nuclear Information System (INIS)

    Jackson, G.; Finley, D.; Johnson, R.P.; Kerns, Q.; McCarthy, J.; Siemann, R.; Zhang, P.

    1988-01-01

    Since the inauguration of colliding proton-antiproton operations in 1987, the Tevatron has exhibited luminosity lifetimes shorter than expected. During a typical colliding beam storage period, called a store, luminosity is calculated periodically by measuring the charge and emittances of each bunch. The growth of the transverse bunch emittances is the dominant cause of luminosity deterioration. Throughout, this period, the position spectrum of the bunches exhibited betatron signals larger than expected from Schottky noise. A model assuming externally driven betatron oscillations explains both the betatron signals and the emittance growth. A program is underway to improve the Tevatron luminosity lifetime. The abort kickers have been identified as sources of emittance growth, and some quadrupole power supplies are further candidates. Because the horizontal dispersion through the RF cavities is nonzero, RF phase noise has been investigated. Noise in the main dipole regulation circuit has also been studied. 13 refs., 4 figs

  16. Angular distributions as lifetime probes

    Energy Technology Data Exchange (ETDEWEB)

    Dror, Jeff Asaf; Grossman, Yuval [Department of Physics, LEPP, Cornell University,Ithaca, NY 14853 (United States)

    2014-06-27

    If new TeV scale particles are discovered, it will be important to determine their width. There is, however, a problematic region, where the width is too small to be determined directly, and too large to generate a secondary vertex. For a collection of colored, spin polarized particles, hadronization depolarizes the particles prior to their decay. The amount of depolarization can be used to probe the lifetime in the problematic region. In this paper we apply this method to a realistic scenario of a top-like particle that can be produced at the LHC. We study how depolarization affects the angular distributions of the decay products and derive an equation for the distributions that is sensitive to the lifetime.

  17. Monosodium glutamate derived tricolor fluorescent carbon nanoparticles for cell-imaging application.

    Science.gov (United States)

    Zheng, Nannan; Ding, Sha; Zhou, Xingping

    2016-06-01

    Fluorescent carbon nanoparticle (FCN) is a new type of carbon-based materials. Because of its wide raw material sources, excellent optical properties and good biocompatibility, FCN is getting more and more attentions. However, its synthesis from resources at low cost under mild conditions is still a challenge. Here we report a novel and simple method derived from monosodium glutamate carbonization to make tricolor fluorescent carbon nanoparticles with an average size below 10nm, a high yield up to 35.2% based on the carbon content in the resource, a long life-time of 3.71ns, and a high fluorescence quantum yield up to 51.5% by using quinine sulfate as the standard substance. We discovered that the fluorescent stability of the FCNs was very excellent under UV irradiation for hours in aqueous solutions of pH ranged from 2.0 to 9.0. The cell viability tested under a pretty high concentration of FCNs indicated their safety for biological applications. Based on their high fluorescence quantum efficiency and the advantages mentioned above, these FCNs were then used for cell imaging and exhibited a perfect performance under 3 kinds of excitation bands (UV, blue, and green lights). Thus, they can be practically applied to immune labeling and imaging in vivo in the near future. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Fluorescence microscopy.

    Science.gov (United States)

    Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

    2014-10-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

  19. New detectors to explore the lifetime frontier

    Science.gov (United States)

    Chou, John Paul; Curtin, David; Lubatti, H. J.

    2017-04-01

    Long-lived particles (LLPs) are a common feature in many beyond the Standard Model theories, including supersymmetry, and are generically produced in exotic Higgs decays. Unfortunately, no existing or proposed search strategy will be able to observe the decay of non-hadronic electrically neutral LLPs with masses above ∼ GeV and lifetimes near the limit set by Big Bang Nucleosynthesis (BBN), cτ ≲107-108 m. We propose the MATHUSLA surface detector concept (MAssive Timing Hodoscope for Ultra Stable neutraL pArticles), which can be implemented with existing technology and in time for the high luminosity LHC upgrade to find such ultra-long-lived particles (ULLPs), whether produced in exotic Higgs decays or more general production modes. We also advocate a dedicated LLP detector at a future 100 TeV collider, where a modestly sized underground design can discover ULLPs with lifetimes at the BBN limit produced in sub-percent level exotic Higgs decays.

  20. Standard test method for determination of bromine and chlorine in UF6 and uranyl nitrate by X-Ray fluorescence (XRF) spectroscopy

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This method covers the determination of bromine (Br) and chlorine (Cl) in uranium hexafluoride (UF6) and uranyl nitrate solution. The method as written covers the determination of bromine in UF6 over the concentration range of 0.2 to 8 μg/g, uranium basis. The chlorine in UF6 can be determined over the range of 4 to 160 μg/g, uranium basis. Higher concentrations may be covered by appropriate dilutions. The detection limit for Br is 0.2 μg/g uranium basis and for Cl is 4 μg/g uranium basis. 1.2 This standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  1. Maintenance engineering of lifetime management programs

    International Nuclear Information System (INIS)

    Hervia Ruperez, F.

    1997-01-01

    The complexity of nuclear power plants obliges to stablish the adecuated management of its lifetime. This article describes the methodologies and the improvement the evaluation of lifetime programs and specially in Garona and Vandellos II Nuclear Power Plants. (Author)

  2. Review of charm and beauty lifetimes

    International Nuclear Information System (INIS)

    Cheung, Harry W. K.

    1999-01-01

    A review of the latest experimental results on charm and beauty particle lifetimes is presented together with a brief summary of measurement methods used for beauty particle lifetime measurements. There have been significant updates to the D s + /D 0 , B + /B d 0 and Λ b 0 /B d 0 lifetime ratios which have some theoretical implications. However more precise measurements are still needed before one can make conclusive statements about the theory used to calculate the particle lifetimes

  3. Towards lifetime electronic health record implementation.

    Science.gov (United States)

    Gand, Kai; Richter, Peggy; Esswein, Werner

    2015-01-01

    Integrated care concepts can help to diminish demographic challenges. Hereof, the use of eHealth, esp. overarching electronic health records, is recognized as an efficient approach. The article aims at rigorously defining the concept of lifetime electronic health records (LEHRs) and the identification of core factors that need to be fulfilled in order to implement such. A literature review was conducted. Existing definitions were identified and relevant factors were categorized. The derived assessment categories are demonstrated by a case study on Germany. Seven dimensions to differentiate types of electronic health records were found. The analysis revealed, that culture, regulation, informational self-determination, incentives, compliance, ICT infrastructure and standards are important preconditions to successfully implement LEHRs. The article paves the way for LEHR implementation and therewith for integrated care. Besides the expected benefits of LEHRs, there are a number of ethical, legal and social concerns, which need to be balanced.

  4. Fluorescence kinetics of Trp-Trp dipeptide and its derivatives in water via ultrafast fluorescence spectroscopy.

    Science.gov (United States)

    Jia, Menghui; Yi, Hua; Chang, Mengfang; Cao, Xiaodan; Li, Lei; Zhou, Zhongneng; Pan, Haifeng; Chen, Yan; Zhang, Sanjun; Xu, Jianhua

    2015-08-01

    Ultrafast fluorescence dynamics of Tryptophan-Tryptophan (Trp-Trp/Trp2) dipeptide and its derivatives in water have been investigated using a picosecond resolved time correlated single photon counting (TCSPC) apparatus together with a femtosecond resolved upconversion spectrophotofluorometer. The fluorescence decay profiles at multiple wavelengths were fitted by a global analysis technique. Nanosecond fluorescence kinetics of Trp2, N-tert-butyl carbonyl oxygen-N'-aldehyde group-l-tryptophan-l-tryptophan (NBTrp2), l-tryptophan-l-tryptophan methyl ester (Trp2Me), and N-acetyl-l-tryptophan-l-tryptophan methyl ester (NATrp2Me) exhibit multi-exponential decays with the average lifetimes of 1.99, 3.04, 0.72 and 1.22ns, respectively. Due to the intramolecular interaction between two Trp residues, the "water relaxation" lifetime was observed around 4ps, and it is noticed that Trp2 and its derivatives also exhibit a new decay with a lifetime of ∼100ps, while single-Trp fluorescence decay in dipeptides/proteins shows 20-30ps. The intramolecular interaction lifetime constants of Trp2, NBTrp2, Trp2Me and NATrp2Me were then calculated to be 3.64, 0.93, 11.52 and 2.40ns, respectively. Candidate mechanisms (including heterogeneity, solvent relaxation, quasi static self-quenching or ET/PT quenching) have been discussed. Copyright © 2015. Published by Elsevier B.V.

  5. On luminescence lifetimes in quartz

    International Nuclear Information System (INIS)

    Chithambo, M.L.; Galloway, R.B.

    2000-01-01

    In this paper we present results of investigations concerning the time dependence of luminescence emission relative to the time of stimulation in quartz. Measurements of time-resolved spectra were performed on a new versatile pulsed light emitting diode system using 525 nm stimulation, an 11 μs duration pulse, a repetition rate of 11 kHz and a 64 μs dynamic range. Effects on luminescence lifetime resulting from sample treatments such as optical stimulation, irradiation, and preheating, are reported

  6. Lifetime measurement in 144Gd

    International Nuclear Information System (INIS)

    Jensen, H.J.; Gast, W.; Georgiev, A.; Jaeger, H.M.; Lieder, R.M.; Utzelmann, S.; Gierlik, M.; Morek, T.; Przestrzelska, K.; Rzaca-Urban, T.; Dewald, A.; Kuehn, R.; Meier, C.; Ender, C.; Haertlein, T.

    1996-01-01

    The lifetime measurements of excited states in 144 Gd were carried out using the Koeln RDM-plunger together with the 2 x 3 CLUSTER detector setup in Heidelberg. The nucleus was populated in the 100 Mo( 48 Ti,4n) 144 Gd reaction at a beam energy of 205 MeV giving a recoil velocity of v/c = 2.6 %. Three and higher fold γ-ray coincidences were measured at 12 target-stopper distances ranged from 0 to 400 μm. Both the dipole and quadrupole bands in 144 Gd have been observed. The analysis is in progress

  7. Lifetime of superheated steam components

    International Nuclear Information System (INIS)

    Stoklossa, K.H.; Oude-Hengel, H.H.; Kraechter, H.J.

    1974-01-01

    The current evaluation schemes in use for judging the lifetime expectations of superheated steam components are compared with each other. The influence of pressure and temperature fluctuations, the differences in the strength of the wall, and the spread band of constant-strainrates are critically investigated. The distribution of these contributory effects are demonstrated in the hight of numerous measuring results. As an important supplement to these evaluation schemes a newly developed technique is introduced which is designed to calculate failure probabilities. (orig./RW) [de

  8. The mass-lifetime relation

    Science.gov (United States)

    LoPresto, Michael C.

    2018-05-01

    In a recent "AstroNote," I described a simple exercise on the mass-luminosity relation for main sequence stars as an example of exposing students in a general education science course of lower mathematical level to the use of quantitative skills such as collecting and analyzing data. Here I present another attempt at a meaningful experience for such students that again involves both the gathering and analysis of numerical data and comparison with accepted result, this time on the relationship of the mass and lifetimes of main sequence stars. This experiment can stand alone or be used as an extension of the previous mass-luminosity relationship experiment.

  9. The puzzle of neutron lifetime

    International Nuclear Information System (INIS)

    Paul, Stephan

    2009-01-01

    In this paper we review the role of the neutron lifetime and discuss the present status of measurements. In view of the large discrepancy observed by the two most precise individual measurements so far we describe the different techniques and point out the principle strengths and weaknesses. In particular we discuss the estimation of systematic uncertainties and its correlation to the statistical ones. In order to solve the present puzzle, many new experiments are either ongoing or being proposed. An overview on their possible contribution to this field will be given.

  10. Personality, IQ, and Lifetime Earnings

    DEFF Research Database (Denmark)

    Gensowski, Miriam

    2018-01-01

    This paper estimates the effects of personality traits and IQ on lifetime earnings of the men and women of the Terman study, a high-IQ U.S. sample. Age-by-age earnings profiles allow a study of when personality traits affect earnings most, and for whom the effects are strongest. I document...... a concave life-cycle pattern in the payoffs to personality traits, with the largest effects between the ages of 40 and 60. An interaction of traits with education reveals that personality matters most for highly educated men. The largest effects are found for Conscientiousness, Extraversion...

  11. Lifetime measurement in 136Pm

    International Nuclear Information System (INIS)

    Toney, D.; Zhong, Q.; De Angelis, G.

    2005-01-01

    The aim of the present work is to investigate the electromagnetic transition probabilities in the doublet bands of 136 Pm. These two bands have been observed up to Iπ = (21 + ). Contrary to the case of 134 Pr, the B(M1)/B(E2) ratios take similar values within the error bars in 136 Pm. This is a strong indication that there is considerable difference between the two nuclei. However, a lifetime measurement in 136 Pm is needed to shed light on the scale and the origin of the difference

  12. Nanodiamond arrays on glass for quantification and fluorescence characterisation.

    Science.gov (United States)

    Heffernan, Ashleigh H; Greentree, Andrew D; Gibson, Brant C

    2017-08-23

    Quantifying the variation in emission properties of fluorescent nanodiamonds is important for developing their wide-ranging applicability. Directed self-assembly techniques show promise for positioning nanodiamonds precisely enabling such quantification. Here we show an approach for depositing nanodiamonds in pre-determined arrays which are used to gather statistical information about fluorescent lifetimes. The arrays were created via a layer of photoresist patterned with grids of apertures using electron beam lithography and then drop-cast with nanodiamonds. Electron microscopy revealed a 90% average deposition yield across 3,376 populated array sites, with an average of 20 nanodiamonds per site. Confocal microscopy, optimised for nitrogen vacancy fluorescence collection, revealed a broad distribution of fluorescent lifetimes in agreement with literature. This method for statistically quantifying fluorescent nanoparticles provides a step towards fabrication of hybrid photonic devices for applications from quantum cryptography to sensing.

  13. Optimized inspection techniques and structural analysis in lifetime management

    International Nuclear Information System (INIS)

    Aguado, M.T.; Marcelles, I.

    1993-01-01

    Preservation of the option of extending the service lifetime of a nuclear power plant beyond its normal design lifetime requires correct remaining lifetime management from the very beginning of plant operation. The methodology used in plant remaining lifetime management is essentially based on the use of standard inspections, surveillance and monitoring programs and calculations, such as thermal-stress and fracture mechanics analysis. The inspection techniques should be continuously optimized, in order to be able to detect and dimension existing defects with the highest possible degree of accuracy. The information obtained during the inspection is combined with the historical data of the components: design, quality, operation, maintenance, and transients, and with the results of destructive testing, fracture mechanics and thermal fatigue analysis. These data are used to estimate the remaining lifetime of nuclear power plant components, systems and structures with the highest degree possible of accuracy. The use of this methodology allows component repairs and replacements to be reduced or avoided and increases the safety levels and availability of the nuclear power plant. Use of this strategy avoids the need for heavy investments at the end of the licensing period

  14. A new technique for the deposition of standard solutions in total reflection X-ray fluorescence spectrometry (TXRF) using pico-droplets generated by inkjet printers and its applicability for aerosol analysis with SR-TXRF

    International Nuclear Information System (INIS)

    Fittschen, U.E.A.; Hauschild, S.; Amberger, M.A.; Lammel, G.; Streli, C.; Foerster, S.; Wobrauschek, P.; Jokubonis, C.; Pepponi, G.; Falkenberg, G.; Broekaert, J.A.C.

    2006-01-01

    A new technique for the deposition of standard solutions on particulate aerosol samples using pico-droplets for elemental determinations with total reflection X-ray fluorescence spectrometry (TXRF) is described. It enables short analysis times without influencing the sample structure and avoids time consuming scanning of the sample with the exciting beam in SR-TXRF analysis. Droplets of picoliter volume (∼ 5-130 pL) were generated with commercially available and slightly modified inkjet printers operated with popular image processing software. The size of the dried droplets on surfaces of different polarity namely silicone coated and untreated quartz reflectors, was determined for five different printer types and ten different cartridge types. The results show that droplets generated by inkjet printers are between 50 and 200 μm in diameter (corresponding to volumes of 5 to 130 pL) depending on the cartridge type, which is smaller than the width of the synchrotron beam used in the experiments (< 1 mm at an energy of 17 keV at the beamline L at HASYLAB, Hamburg). The precision of the printing of a certain amount of a single element standard solution was found to be comparable to aliquoting with micropipettes in TXRF, where for 2.5 ng of cobalt relative standard deviations of 12% are found. However, it could be shown that the printing of simple patterns is possible, which is important when structured samples have to be analysed

  15. Enhancement of uranyl fluorescence using trimesic acid: Ligand sensitization and co-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Maji, S. [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Viswanathan, K.S., E-mail: vish@igcar.gov.in [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2011-09-15

    Trimesic acid (TMA) was shown to sensitize and enhance uranyl fluorescence in aqueous medium, with the enhancement being a maximum at pH 5.0. Fluorescence spectra and lifetime data together suggest that TMA complexes with uranyl (UO{sub 2}{sup 2+}). The fluorescence of UO{sub 2}{sup 2+} in its acid complex is further enhanced by more than two orders of magnitude following the addition of Y{sup 3+}; a process referred to as co-fluorescence, leading to the possibility of detecting uranium at sub ng/mL level. The present study demonstrates, for the first time, fluorescence enhancement of the uranyl species due to co-fluorescence. - Highlights: > Trimesic acid was shown to sensitize and enhance the fluorescence of uranium in aqueous medium. > This ligand also exhibited co-fluorescence of uranium with Y{sup 3+}. > To the best of our knowledge this is the first report of co-fluorescence in uranium. > The enhancement of uranium fluorescence, resulted in detection limits in the ng/mL regime.

  16. Fluorescence detection of esophageal neoplasia

    Science.gov (United States)

    Borisova, E.; Vladimirov, B.; Avramov, L.

    2008-06-01

    White-light endoscopy is well-established and wide used modality. However, despite the many technological advances that have been occurred, conventional endoscopy is suboptimal and usually detects advanced stage lesions. The limitations of standard endoscopy initiate development of spectroscopic techniques, additional to standard endoscopic equipment. One of the most sensitive approaches is fluorescence spectroscopy of gastrointestinal mucosa for neoplasia detection. In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. Excitation source has max of emission at 405 nm and light is delivered by the standard light guide of the endoscopic equipment. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to reabsorption of blood. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of 5-ALA/PpIX only in abnormal sites Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

  17. Uncertainties in the proton lifetime

    International Nuclear Information System (INIS)

    Ellis, J.; Nanopoulos, D.V.; Rudaz, S.; Gaillard, M.K.

    1980-04-01

    We discuss the masses of the leptoquark bosons m(x) and the proton lifetime in Grand Unified Theories based principally on SU(5). It is emphasized that estimates of m(x) based on the QCD coupling and the fine structure constant are probably more reliable than those using the experimental value of sin 2 theta(w). Uncertainties in the QCD Λ parameter and the correct value of α are discussed. We estimate higher order effects on the evolution of coupling constants in a momentum space renormalization scheme. It is shown that increasing the number of generations of fermions beyond the minimal three increases m(X) by almost a factor of 2 per generation. Additional uncertainties exist for each generation of technifermions that may exist. We discuss and discount the possibility that proton decay could be 'Cabibbo-rotated' away, and a speculation that Lorentz invariance may be violated in proton decay at a detectable level. We estimate that in the absence of any substantial new physics beyond that in the minimal SU(5) model the proton lifetimes is 8 x 10 30+-2 years

  18. Standardization of a sulfur quantitative analysis method by X ray fluorescence in a leaching solution for bio-available sulfates in soil

    International Nuclear Information System (INIS)

    Morales S, E.; Aguilar S, E.

    1989-11-01

    A method for bio-available sulfate analysis in soils is described. A Ca(H2PO4) leaching solution was used for soil samples treatment. A standard NaSO4 solution was used for preparing a calibration curve and also the fundamental parameters method approach was employed. An Am-241 (100 mCi) source and a Si-Li detector were employed. Analysis could be done in 5 minutes; good reproducibility, 5 and accuracy, 5 were obtained. The method is very competitive with conventional nephelometry where good and reproducible suspensions are difficult to obtain. (author)

  19. Fluorescent nanoparticles for intracellular sensing: a review.

    Science.gov (United States)

    Ruedas-Rama, Maria J; Walters, Jamie D; Orte, Angel; Hall, Elizabeth A H

    2012-11-02

    Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Steady state and time-resolved fluorescence spectroscopy of quinine sulfate dication bound to sodium dodecylsulfate micelles: Fluorescent complex formation

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Sunita; Pant, Debi D., E-mail: ddpant@pilani.bits-pilani.ac.in

    2014-01-15

    Interaction of quinine sulfate dication (QSD) with anionic, sodium dodecylsulphate (SDS) surfactant has been studied at different premicellar, micellar and postmicellar concentrations in aqueous phase using steady state, time-resolved fluorescence and fluorescence anisotropy techniques. At premicellar concentrations of SDS, the decrease in absorbance, appearance of an extra fluorescence band at lower wavelengths and tri-exponential decay behavior of fluorescence, are attributed to complex formation between QSD molecules and surfactant monomers. At postmicellar concentrations the red shift in fluorescence spectrum, increase in quantum yield and increase in fluorescence lifetimes are attributed to incorporation of solute molecules to micelles. At lower concentrations of SDS, a large shift in fluorescence is observed on excitation at the red edge of absorption spectrum and this is explained in terms of distribution of ion pairs of different energies in the ground state and the observed fluorescence lifetime behavior corroborates with this model. The temporal fluorescence anisotropy decay of QSD in SDS micelles allowed determination of restriction on the motion of the fluorophore. All the different techniques used in this study reveal that the photophysics of QSD is very sensitive to the microenvironments of SDS micelles and QSD molecules reside at the water-micelle interface. -- Highlights: • Probe molecule is very sensitive to microenvironment of micelles. • Highly fluorescent ion-pair formation has been observed. • Modulated photophysics of probe molecule in micellar solutions has been observed. • Probe molecules strongly bind with micelles and reside at probe–micelle interface.

  1. Combination of confocal principle and aperture stop separation improves suppression of crystalline lens fluorescence in an eye model

    OpenAIRE

    Klemm, Matthias; Blum, Johannes; Link, Dietmar; Hammer, Martin; Haueisen, Jens; Schweitzer, Dietrich

    2016-01-01

    Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique to detect changes in the human retina. The autofluorescence decay over time, generated by endogenous fluorophores, is measured in vivo. The strong autofluorescence of the crystalline lens, however, superimposes the intensity decay of the retina fluorescence, as the confocal principle is not able to suppress it sufficiently. Thus, the crystalline lens autofluorescence causes artifacts in the retinal fluorescence lifetimes d...

  2. Spectrum Fatigue Lifetime and Residual Strength for Fiberglass Laminates; TOPICAL

    International Nuclear Information System (INIS)

    WAHL, NEIL K.; MANDELL, JOHN F.; SAMBORSKY, DANIEL D.

    2002-01-01

    This report addresses the effects of spectrum loading on lifetime and residual strength of a typical fiberglass laminate configuration used in wind turbine blade construction. Over 1100 tests have been run on laboratory specimens under a variety of load sequences. Repeated block loading at two or more load levels, either tensile-tensile, compressive-compressive, or reversing, as well as more random standard spectra have been studied. Data have been obtained for residual strength at various stages of the lifetime. Several lifetime prediction theories have been applied to the results. The repeated block loading data show lifetimes that are usually shorter than predicted by the most widely used linear damage accumulation theory, Miner's sum. Actual lifetimes are in the range of 10 to 20 percent of predicted lifetime in many cases. Linear and nonlinear residual strength models tend to fit the data better than Miner's sum, with the nonlinear providing a better fit of the two. Direct tests of residual strength at various fractions of the lifetime are consistent with the residual strength models. Load sequencing effects are found to be insignificant. The more a spectrum deviates from constant amplitude, the more sensitive predictions are to the damage law used. The nonlinear model provided improved correlation with test data for a modified standard wind turbine spectrum. When a single, relatively high load cycle was removed, all models provided similar, though somewhat non-conservative correlation with the experimental results. Predictions for the full spectrum, including tensile and compressive loads were slightly non-conservative relative to the experimental data, and accurately captured the trend with varying maximum load. The nonlinear residual strength based prediction with a power law S-N curve extrapolation provided the best fit to the data in most cases. The selection of the constant amplitude fatigue regression model becomes important at the lower stress, higher

  3. Nonmesonic decays and lifetimes of hypernuclei

    International Nuclear Information System (INIS)

    Itonaga, K.; Ueda, T.; Motoba, T.

    2002-01-01

    The nonmesonic decay rates and the lifetimes of hypernuclei of mass A=4-209 are extensively calculated based on the 1π, correlated-2π, and 1ω exchange potentials. Two types of new hyperon-nucleon potentials have been constructed in which the two pions are correlated and coupled to ρ and/or σ in the exchange process. The roles of these potentials and 1ω exchange potential are discussed. The theoretical decay rates are consistent with the existing data for s-shell and p-shell hypernuclei within the present model. The calculated decay rate increases gradually up to A≅60 and then tends to be almost constant for A(greater-or-similar sign)60. The A-dependent behavior of the hypernuclear lifetimes tends to be constant over the mass region A>30 of hypernuclei in our model. It is most remarkable that the cooperative effect of the correlated-2π and 1ω exchanges enhances the neutron-stimulated decay rate Γ n (proton-stimulated one Γ p ) by 400-450 % (20-30 %) with respect to the standard 1π-exchange estimate for A>5. As a result the Γ n /Γ p ratios for light-to-heavy hypernuclei are calculated to be 0.4-0.5, which values are several times larger than the 1π-exchange estimate. Although the experimental ratios seem still about two times larger than these theoretical values, it has revealed that the representative 2π-exchange and 1ω exchange mechanisms give rise to a clear improvement on the Γ n /Γ p ratios

  4. Personality, IQ, and Lifetime Earnings

    DEFF Research Database (Denmark)

    Gensowski, Miriam

    2014-01-01

    Talented individuals are seen as drivers of long-term growth, but how do they realize their full potential? In this paper, I show that lifetime earnings of high-IQ men and women are substantially influenced by their personality traits, in addition to intelligence and education. Personality traits......, as identified in a factor model, significantly affect earnings, but not for young workers. The effects are furthermore heterogeneous by educational attainment. For women, personality traits do not affect family earnings in the same way as own earnings. Personality and IQ also influence earnings indirectly...... through education, which has sizeable positive rates of return for men in this sample. Women’s returns to education past a bachelor’s degree are lowered through worse marriage prospects, which offset gains to education in terms of own earnings. The causal effect of education is identified through matching...

  5. Measurement of the BS lifetime

    International Nuclear Information System (INIS)

    Siccama, I.

    1996-01-01

    This thesis presents a measurement of the B s lifetime using 3 million hadronic Z decays collected by the DELPHI detector at LEP from 1991 to 1994. Decays of B s mesons are tagged by the reconstruction of a D s - →φπ - or D s - →K *0 K - decay (including the charge conjugated states of these decay modes). The decay time is obtained by reconstructing both the B s momentum and the B s flight distance. The combined result for the D s -lepton and D s -hadron samples is: τ(B s )=1.54±0.31±0.15 ps where the first error is statistical and the second is systematic. (orig./HSI)

  6. Lifetime of Organic Photovoltaics: Status and Predictions

    DEFF Research Database (Denmark)

    Gevorgyan, Suren; Madsen, Morten Vesterager; Roth, Bérenger

    2016-01-01

    The results of a meta-analysis conducted on organic photovoltaics (OPV) lifetime data reported in the literature is presented through the compilation of an extensive OPV lifetime database based on a large number of articles, followed by analysis of the large body of data. We fully reveal the prog......The results of a meta-analysis conducted on organic photovoltaics (OPV) lifetime data reported in the literature is presented through the compilation of an extensive OPV lifetime database based on a large number of articles, followed by analysis of the large body of data. We fully reveal...... the progress of reported OPV lifetimes. Furthermore, a generic lifetime marker has been defi ned, which helps with gauging and comparing the performance of different architectures and materials from the perspective of device stability. Based on the analysis, conclusions are drawn on the bottlenecks...

  7. The Susquehanna plant lifetime excellence program

    International Nuclear Information System (INIS)

    McNamara, R.W.

    1988-01-01

    This paper discusses how the Susquehanna plant lifetime excellence program (SPLEX) blends many of the objectives of a new managing for excellence program with plant life extension objectives to achieve excellence in the lifetime operation and availability of the two-unit Susquehanna steam electric station. Investments in lifetime excellence improvements will provide near-term, as well as plant life extension, benefits. A high-quality lifetime experience record, together with extensive, periodic technical assessments and cost-benefit analyses, will provide conclusive justification for future extensions of the unit operating licenses

  8. Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.

    Science.gov (United States)

    Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

    2014-07-09

    Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 μs in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (ΔEST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ΔE(ST) was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies.

  9. Fluorescence spectroscopy and confocal microscopy of the mycotoxin citrinin in condensed phase and hydrogel films.

    Science.gov (United States)

    Lauer, Milena H; Gehlen, Marcelo H; de Jesus, Karen; Berlinck, Roberto G S

    2014-05-01

    The emission spectra, quantum yields and fluorescence lifetimes of citrinin in organic solvents and hydrogel films have been determined. Citrinin shows complex fluorescence decays due to the presence of two tautomers in solution and interconversion from excited-state double proton transfer (ESDPT) process. The fluorescence decay times associated with the two tautomers have values near 1 and 5 ns depending on the medium. In hydrogel films of agarose and alginate, fluorescence imaging showed that citrinin is not homogeneously dispersed and highly emissive micrometer spots may be formed. Fluorescence spectrum and decay analysis are used to recognize the presence of citrinin in hydrogel films using confocal fluorescence microscopy and spectroscopy.

  10. Measurement of the neutron lifetime by counting trapped protons

    International Nuclear Information System (INIS)

    Byrne, J.; Dawber, P.G.; Spain, J.A.; Williams, A.P.; Dewey, M.S.; Gilliam, D.M.; Greene, G.L.; Lamaze, G.P.; Scott, R.D.; Pauwels, J.; Eykens, R.; Lamberty, A.

    1990-01-01

    The neutron lifetime τ n has been measured by counting decay protons stored in a Penning trap whose magnetic axis coincided with a neutron-beam axis. The result of the measurement is τ n =893.6±5.3 s, which agrees well with the value predicted by precise measurements of the β-decay asymmetry parameter A and the standard model

  11. Improving fluorescence diagnosis of cancer by SLIM

    Science.gov (United States)

    Rück, Angelika; Dolp, Frank; Kinzler, Ingrid; Hauser, Carmen; Scalfi-Happ, Claudia

    2006-02-01

    Although during the last years, significant progress was made in cancer diagnosis, using either intrinsic or specially designed fluorophores, still problems exist, due to difficulties in spectral separation of highly overlapping probes or in lack of specificity. Many of the problems could be circumvented by focusing on time-resolved methods. In combination with spectral resolved detection (spectral fluorescence lifetime imaging, SLIM) highly sophisticated fluorescence lifetime imaging can be performed which might improve specificity of cell diagnosis. To record lifetime images (τ-mapping) with spectral resolution a setup was realized consisting of a laser scanning microscope equipped with a 16 channel array for time-correlated single photon counting (TCSPC) and a spectrograph in front of the array. A Ti:Saphir laser can be used for excitation or alternatively ps diode lasers. With this system the time- and spectral-resolved fluorescence characteristics of different fluorophores were investigated in solution and in cell culture. As an example, not only the mitochondria staining dye rhodamine 123 could be easily distinguished from DAPI, which intercalates into nucleic acids, but also different binding sites of DAPI. This was proved by the appearance of different lifetime components within different spectral channels. Another example is Photofrin, a photosensitizer which is approved for bladder cancer and for palliative lung and esophageal cancer in 20 countries, including the United States, Canada and many European countries. Photofrin is a complex mixture of different monomeric and aggregated porphyrins. The phototoxic efficiency during photodynamic therapy (PDT) seems to be correlated with the relative amounts of monomers and aggregates. With SLIM different lifetimes could be attributed to various, spectrally highly overlapping compounds. In addition, a detailed analysis of the autofluorescence by SLIM could explain changes of mitochondrial metabolism during

  12. Lifetime Extension Report: Progress on the SAVY-4000 Lifetime Extension Program

    International Nuclear Information System (INIS)

    Welch, Cynthia F.; Smith, Paul Herrick; Weis, Eric M.; Blair, Michael W.; Stone, Timothy Amos; Veirs, Douglas Kirk; Reeves, Kirk Patrick; Karns, Tristan; Oka, Jude M.; Keller, Jennie; Meincke, Linda Jeanne; Torres, Joseph Angelo; Herman, Matthew Joseph; Weaver, Brian Phillip; Adams, Jillian Cathleen; Trautschold, Olivia Carol

    2016-01-01

    The 3-year accelerated aging study of the SAVY-4000 O-ring shows very little evidence of significant degradation to samples subjected to aggressive elevated temperature and radiation conditions. Whole container thermal aging studies followed by helium leakage testing and compression set measurements were used to establish an estimate for a failure criterion for O-ring compression set of ?65 %. The whole container aging studies further show that the air flow and efficiency functions of the filter do not degrade significantly after thermal aging. However, the degradation of the water-resistant function leads to water penetration failure after four months at 210°C, but does not cause failure after 10 months at 120°C (130°C is the maximum operating temperature for the PTFE membrane). The thermal aging data for O-ring compression set do not meet the assumptions of standard time-temperature superposition analysis for accelerated aging studies. Instead, the data suggest that multiple degradation mechanisms are operative, with a reversible mechanism operative at low aging temperatures and an irreversible mechanism dominating at high aging temperatures. To distinguish between these mechanisms, we have measured compression set after allowing the sample to physically relax, thereby minimizing the effect of the reversible mechanism. The resulting data were analyzed using two distinct mathematical methods to obtain a lifetime estimate based on chemical degradation alone. Both methods support a lifetime estimate of greater than 150 years at 80°C. Although the role of the reversible mechanism is not fully understood, it is clear that the contribution to the total compression set is small in comparison to that due to the chemical degradation mechanism. To better understand the chemical degradation mechanism, thermally aged O-ring samples have been characterized by Fourier Transform Infrared (FTIR), Electron Paramagnetic Resonance (EPR), Gel Permeation Chromatography (GPC), and

  13. Lifetime Extension Report: Progress on the SAVY-4000 Lifetime Extension Program

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Cynthia F. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Smith, Paul Herrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Process Infrastructure; Weis, Eric M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Blair, Michael W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Stone, Timothy Amos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Process Infrastructure; Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Manufacturing Engineering and Technology; Reeves, Kirk Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Process Infrastructure; Karns, Tristan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Process Infrastructure; Oka, Jude M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Process Infrastructure; Keller, Jennie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Meincke, Linda Jeanne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Torres, Joseph Angelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Herman, Matthew Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Weaver, Brian Phillip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences. Statistical Sciences; Adams, Jillian Cathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials; Trautschold, Olivia Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology. Engineered Materials

    2016-09-20

    The 3-year accelerated aging study of the SAVY-4000 O-ring shows very little evidence of significant degradation to samples subjected to aggressive elevated temperature and radiation conditions. Whole container thermal aging studies followed by helium leakage testing and compression set measurements were used to establish an estimate for a failure criterion for O-ring compression set of ≥65 %. The whole container aging studies further show that the air flow and efficiency functions of the filter do not degrade significantly after thermal aging. However, the degradation of the water-resistant function leads to water penetration failure after four months at 210°C, but does not cause failure after 10 months at 120°C (130°C is the maximum operating temperature for the PTFE membrane). The thermal aging data for O-ring compression set do not meet the assumptions of standard time-temperature superposition analysis for accelerated aging studies. Instead, the data suggest that multiple degradation mechanisms are operative, with a reversible mechanism operative at low aging temperatures and an irreversible mechanism dominating at high aging temperatures. To distinguish between these mechanisms, we have measured compression set after allowing the sample to physically relax, thereby minimizing the effect of the reversible mechanism. The resulting data were analyzed using two distinct mathematical methods to obtain a lifetime estimate based on chemical degradation alone. Both methods support a lifetime estimate of greater than 150 years at 80°C. Although the role of the reversible mechanism is not fully understood, it is clear that the contribution to the total compression set is small in comparison to that due to the chemical degradation mechanism. To better understand the chemical degradation mechanism, thermally aged O-ring samples have been characterized by Fourier Transform Infrared (FTIR), Electron Paramagnetic Resonance (EPR), Gel Permeation Chromatography (GPC

  14. Double-gated spectral snapshots for biomolecular fluorescence

    International Nuclear Information System (INIS)

    Nakamura, Ryosuke; Hamada, Norio; Ichida, Hideki; Tokunaga, Fumio; Kanematsu, Yasuo

    2007-01-01

    A versatile method to take femtosecond spectral snapshots of fluorescence has been developed based on a double gating technique in the combination of an optical Kerr gate and an image intensifier as an electrically driven gate set in front of a charge-coupled device detector. The application of a conventional optical-Kerr-gate method is limited to molecules with the short fluorescence lifetime up to a few hundred picoseconds, because long-lifetime fluorescence itself behaves as a source of the background signal due to insufficiency of the extinction ratio of polarizers employed for the Kerr gate. By using the image intensifier with the gate time of 200 ps, we have successfully suppressed the background signal and overcome the application limit of optical-Kerr-gate method. The system performance has been demonstrated by measuring time-resolved fluorescence spectra for laser dye solution and the riboflavin solution as a typical sample of biomolecule

  15. Fusion-component lifetime analysis

    International Nuclear Information System (INIS)

    Mattas, R.F.

    1982-09-01

    A one-dimensional computer code has been developed to examine the lifetime of first-wall and impurity-control components. The code incorporates the operating and design parameters, the material characteristics, and the appropriate failure criteria for the individual components. The major emphasis of the modeling effort has been to calculate the temperature-stress-strain-radiation effects history of a component so that the synergystic effects between sputtering erosion, swelling, creep, fatigue, and crack growth can be examined. The general forms of the property equations are the same for all materials in order to provide the greatest flexibility for materials selection in the code. The individual coefficients within the equations are different for each material. The code is capable of determining the behavior of a plate, composed of either a single or dual material structure, that is either totally constrained or constrained from bending but not from expansion. The code has been utilized to analyze the first walls for FED/INTOR and DEMO and to analyze the limiter for FED/INTOR

  16. Aspects of silicon bulk lifetimes

    Science.gov (United States)

    Landsberg, P. T.

    1985-01-01

    The best lifetimes attained for bulk crytalline silicon as a function of doping concentrations are analyzed. It is assumed that the dopants which set the Fermi level do not contribute to the recombination traffic which is due to the unknown defect. This defect is assumed to have two charge states: neutral and negative, the neutral defect concentration is frozen-in at some temperature T sub f. The higher doping concentrations should include the band-band Auger effect by using a generalization of the Shockley-Read-Hall (SRH) mechanism. The generalization of the SRH mechanism is discussed. This formulation gives a straightforward procedure for incorporating both band-band and band-trap Auger effects in the SRH procedure. Two related questions arise in this context: (1) it may sometimes be useful to write the steady-state occupation probability of the traps implied by SRH procedure in a form which approximates to the Fermi-Dirac distribution; and (2) the effect on the SRH mechanism of spreading N sub t levels at one energy uniformly over a range of energies is discussed.

  17. Baselines for Lifetime of Organic Solar Cells

    DEFF Research Database (Denmark)

    Gevorgyan, Suren; Espinosa Martinez, Nieves; Ciammaruchi, Laura

    2016-01-01

    The process of accurately gauging lifetime improvements in organic photovoltaics (OPVs) or other similar emerging technologies, such as perovskites solar cells is still a major challenge. The presented work is part of a larger effort of developing a worldwide database of lifetimes that can help...

  18. Maximizing System Lifetime by Battery Scheduling

    NARCIS (Netherlands)

    Jongerden, M.R.; Haverkort, Boudewijn R.H.M.; Bohnenkamp, H.C.; Katoen, Joost P.

    2009-01-01

    The use of mobile devices is limited by the battery lifetime. Some devices have the option to connect an extra battery, or to use smart battery-packs with multiple cells to extend the lifetime. In these cases, scheduling the batteries over the load to exploit recovery properties usually extends the

  19. Explore the Lifetime Frontiers with MATHUSLA Detector

    CERN Document Server

    Zhang, Ce; CERN. Geneva. EP Department

    2017-01-01

    Many extensions of the Standard Model (SM) include particles that are neutral, weakly coupled, and long-lived that can decay to final states containing several hadronic jets. Long-lived particles (LLPs) can be detected as displaced decays from the interaction point, or missing energy if they escape. ATLAS and CMS have performed searches at the LHC and significant exclusion limits have been set in recent years. However, the current searches performed at colliders have limitations. An LLP does not interact with the detector and it is only visible once it decays. Unfortunately, no existing or proposed search strategy will be able to observe the decay of non-hadronic electrically neutral LLPs with masses above ~ GeV and lifetimes near the limit set by Big Bang Nucleosynthesis ($c\\tau \\sim 10^7-10^8 m$). Therefore, ultra-long-lived particles (ULLPs) produced at the LHC will escape the main detector with extremely high probability. MATHUSLA (MAssive Timing Hodoscope for Ultra Stable neutraL pArticles) is a surface ...

  20. Lifetime of titanium filament at constant current

    International Nuclear Information System (INIS)

    Chou, T.S.; Lanni, C.

    1981-01-01

    Titanium Sublimation Pump (TSP) represents the most efficient and the least expensive method to produce Ultra High Vacuum (UHV) in storage rings. In ISABELLE, a proton storage accelerator under construction at Brookhaven National Laboratory, for example, TSP provides a pumping speed for hydrogen of > 2 x 10 6 l/s. Due to the finite life of titanium filaments, new filaments have to be switched in before the end of filament burn out, to ensure smooth operation of the accelerator. Therefore, several operational modes that can be used to activate the TSP were studied. The constant current mode is a convenient way of maintaining constant evaporating rate by increasing the power input while the filament diameter decreases as titanium evaporates. The filaments used in this experiment were standard Varian 916-0024 filaments made of Ti 85%, Mo 15% alloy. During their lifetime at a constant current of 48 amperes, the evaporation rate rose to a maximum at about 10% of their life and then flattened out to a constant value, 0.25 g/hr. The maximum evaporation rate occurs coincidently with the recrystallization of 74% Ti 26% Mo 2 from microstructure crystalline at higher titanium concentration to macrostructure crystalline at lower titanium concentration. As the macrocrystal grows, the slip plane develops at the grain boundary resulting in high resistance at the slip plane which will eventually cause the filament burn out due to local heating

  1. Monte Carlo modeling of time-resolved fluorescence for depth-selective interrogation of layered tissue.

    Science.gov (United States)

    Pfefer, T Joshua; Wang, Quanzeng; Drezek, Rebekah A

    2011-11-01

    Computational approaches for simulation of light-tissue interactions have provided extensive insight into biophotonic procedures for diagnosis and therapy. However, few studies have addressed simulation of time-resolved fluorescence (TRF) in tissue and none have combined Monte Carlo simulations with standard TRF processing algorithms to elucidate approaches for cancer detection in layered biological tissue. In this study, we investigate how illumination-collection parameters (e.g., collection angle and source-detector separation) influence the ability to measure fluorophore lifetime and tissue layer thickness. Decay curves are simulated with a Monte Carlo TRF light propagation model. Multi-exponential iterative deconvolution is used to determine lifetimes and fractional signal contributions. The ability to detect changes in mucosal thickness is optimized by probes that selectively interrogate regions superficial to the mucosal-submucosal boundary. Optimal accuracy in simultaneous determination of lifetimes in both layers is achieved when each layer contributes 40-60% of the signal. These results indicate that depth-selective approaches to TRF have the potential to enhance disease detection in layered biological tissue and that modeling can play an important role in probe design optimization. Published by Elsevier Ireland Ltd.

  2. Fully time-resolved near-field scanning optical microscopy fluorescence imaging

    International Nuclear Information System (INIS)

    Kwak, Eun-Soo; Vanden Bout, David A.

    2003-01-01

    Time-correlated single photon counting has been coupled with near-field scanning optical microscopy (NSOM) to record complete fluorescence lifetime decays at each pixel in an NSOM image. The resulting three-dimensional data sets can be binned in the time dimension to create images of photons at particular time delays or images of the fluorescence lifetime. Alternatively, regions of interest identified in the topography and fluorescence images can be used to bin the data in the spatial dimensions resulting in high signal to noise fluorescence decays of particular regions of the sample. The technique has been demonstrated on films of poly(vinylalcohol), doped with the fluorescent dye, cascade blue (CB). The CB segregates into small circular regions of high concentration within the films during the drying process. The lifetime imaging shows that the spots have slightly faster excited state decays due to quenching of the luminescence as a result of the higher concentration. The technique is also used to image the fluorescence lifetime of an annealed film of poly(dihexylfluorene). The samples show high contrast in the total intensity fluorescence image, but the lifetime image reveals the sample to be extremely uniform

  3. Autofluorescence lifetime imaging during transoral robotic surgery: a clinical validation study of tumor detection (Conference Presentation)

    Science.gov (United States)

    Lagarto, João. L.; Phipps, Jennifer E.; Unger, Jakob; Faller, Leta M.; Gorpas, Dimitris; Ma, Dinglong M.; Bec, Julien; Moore, Michael G.; Bewley, Arnaud F.; Yankelevich, Diego R.; Sorger, Jonathan M.; Farwell, Gregory D.; Marcu, Laura

    2017-02-01

    Autofluorescence lifetime spectroscopy is a promising non-invasive label-free tool for characterization of biological tissues and shows potential to report structural and biochemical alterations in tissue owing to pathological transformations. In particular, when combined with fiber-optic based instruments, autofluorescence lifetime measurements can enhance intraoperative diagnosis and provide guidance in surgical procedures. We investigate the potential of a fiber-optic based multi-spectral time-resolved fluorescence spectroscopy instrument to characterize the autofluorescence fingerprint associated with histologic, morphologic and metabolic changes in tissue that can provide real-time contrast between healthy and tumor regions in vivo and guide clinicians during resection of diseased areas during transoral robotic surgery. To provide immediate feedback to the surgeons, we employ tracking of an aiming beam that co-registers our point measurements with the robot camera images and allows visualization of the surgical area augmented with autofluorescence lifetime data in the surgeon's console in real-time. For each patient, autofluorescence lifetime measurements were acquired from normal, diseased and surgically altered tissue, both in vivo (pre- and post-resection) and ex vivo. Initial results indicate tumor and normal regions can be distinguished based on changes in lifetime parameters measured in vivo, when the tumor is located superficially. In particular, results show that autofluorescence lifetime of tumor is shorter than that of normal tissue (p robot assisted cancer removal interventions.

  4. Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

    International Nuclear Information System (INIS)

    Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

    1994-01-01

    Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe

  5. Nanostructure induced changes in lifetime and enhanced second-harmonic response of organic-plasmonic hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Leißner, Till [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark); Kostiučenko, Oksana; Rubahn, Horst-Günter; Fiutowski, Jacek, E-mail: fiutowski@mci.sdu.dk [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Brewer, Jonathan R. [Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark)

    2015-12-21

    In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32 ns for unstructured gold films to 0.22 ns for gold nanosquare arrays, demonstrating efficient organic–plasmonic interaction. To study the origin of these effects, we applied two-photon laser scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry.

  6. Fluorescein Derivatives in Intravital Fluorescence Imaging

    Directory of Open Access Journals (Sweden)

    Michael S. Roberts

    2013-08-01

    Full Text Available Intravital fluorescence microscopy enables the direct imaging of fluorophores in vivo and advanced techniques such as fluorescence lifetime imaging (FLIM enable the simultaneous detection of multiple fluorophores. Consequently, it is now possible to record distribution and metabolism of a chemical in vivo and to optimise the delivery of fluorophores in vivo. Recent clinical applications with fluorescein and other intravital fluorescent stains have occurred in neurosurgery, dermatology [including photodynamic therapy (PDT] and endomicroscopy. Potential uses have been identified in periodontal disease, skin graft and cancer surgery. Animal studies have demonstrated that diseased tissue can be specifically stained with fluorophore conjugates. This review focuses on the fluorescein derived fluorophores in common clinical use and provides examples of novel applications from studies in tissue samples.

  7. Nuclear Power Plant Lifetime Management Study (I)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Yull; Jeong, Ill Seok; Jang, Chang Heui; Song, Taek Ho; Song, Woo Young [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Jin, Tae Eun [Korea Power Engineering Company Consulting and Architecture Engineers, (Korea, Republic of); Kim, Woo Chul [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    As the operation-year of nuclear power plant increases and finding sites for new nuclear power plant becomes harder, a comprehensive and systematic nuclear plant lifetime management(PLIM) program including life extension has to be established for stable and safe supply of electricity. A feasibility study was conducted to systematically evaluate technical, economic and regulatory aspect of plant lifetime managements and plant life extension for Kori-1 nuclear power plant. For technical evaluation of nuclear power plant, 13 major components were selected for lifetime evaluation by screening system. structure, and components(SSCs) of the plant. It was found that except reactor pressure vessel, which needs detailed integrity analysis, and low pressure turbine, which is scheduled to be replaced, 11 out of 13 major components have sufficient service life, for more than 40 years. Because domestic rules and regulations related to license renewal has not yet been written, review on the regulatory aspect of life extensions was conducted using US NRC rules and regulations. A cooperative effort with nuclear regulatory body is needed for early completion of license renewal rules and regulations. For economic evaluation of plant lifetime extension, a computer program was developed and used. It was found that 10 to 20 year of extension operation of Kori-1 nuclear power plant was proved. Based on the results, next phase of plant lifetime management program for detailed lifetime evaluation and presenting detailed implementation schedule for plant refurbishment for lifetime extension should be followed. (author). 74 refs., figs.

  8. Nuclear Power Plant Lifetime Management Study (I)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Yull; Jeong, Ill Seok; Jang, Chang Heui; Song, Taek Ho; Song, Woo Young [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Jin, Tae Eun [Korea Power Engineering Company Consulting and Architecture Engineers, (Korea, Republic of); Kim, Woo Chul [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-12-31

    As the operation-year of nuclear power plant increases and finding sites for new nuclear power plant becomes harder, a comprehensive and systematic nuclear plant lifetime management(PLIM) program including life extension has to be established for stable and safe supply of electricity. A feasibility study was conducted to systematically evaluate technical, economic and regulatory aspect of plant lifetime managements and plant life extension for Kori-1 nuclear power plant. For technical evaluation of nuclear power plant, 13 major components were selected for lifetime evaluation by screening system. structure, and components(SSCs) of the plant. It was found that except reactor pressure vessel, which needs detailed integrity analysis, and low pressure turbine, which is scheduled to be replaced, 11 out of 13 major components have sufficient service life, for more than 40 years. Because domestic rules and regulations related to license renewal has not yet been written, review on the regulatory aspect of life extensions was conducted using US NRC rules and regulations. A cooperative effort with nuclear regulatory body is needed for early completion of license renewal rules and regulations. For economic evaluation of plant lifetime extension, a computer program was developed and used. It was found that 10 to 20 year of extension operation of Kori-1 nuclear power plant was proved. Based on the results, next phase of plant lifetime management program for detailed lifetime evaluation and presenting detailed implementation schedule for plant refurbishment for lifetime extension should be followed. (author). 74 refs., figs.

  9. Lifetime management of the nuclear units in France

    International Nuclear Information System (INIS)

    Combes, J-P.; Godin, R.

    1994-01-01

    A systematic design study entitled 'Lifetime Project' has been initiated at Electricite de France, to estimate, plan, and maximize the life span of the French PWR plants. It is estimated that the present units will have a lifetime of 30 to 50 years. The life of a unit will be determined by that of its components, by economic considerations (whether it is cheaper to repair or replace the unit), and by safety considerations, which may be affected by changing safety standards. A 'periodic safety reassessment' takes place about every ten years. A list of 18 critical components can be summarized by saying that the main concerns are: radiation embrittlement of and within the reactor vessel, the steam generators, the concrete containment (which can not be replaced), instrumentation and control. Examination of samples from decommissioned plants, such as Chooz A, will provide valuable evidence of mechanisms of degradation due to aging

  10. DEFORMATION INFLUENCE ON A LIFETIME OF WELDING ELECTRODE TIPS

    Directory of Open Access Journals (Sweden)

    Ján Viňáš

    2009-02-01

    Full Text Available The contribution deals with the influence of welding electrode tips deformation on their lifetime. The influence of material properties, production technology and the intensity of welding electrodes load on their lifetime are presented. The electrode tips of the most used type of CuCr1Zr alloy of three basic standard shapes before and after the process of welding are evaluated. The process of welding is realized with low, middle and maximum welding parameters on programmable pneumatic spot welding machine VTS BPK 20. The influence of welding parameters on chosen material characteristics of welding tips is observed. Through the use of upsetting test, dependency of forming strength and deformation of material on used technology of welding tip production is observed.

  11. Lifetime measurement of ATF damping ring

    International Nuclear Information System (INIS)

    Okugi, T.; Hayano, H.; Kubo, K.; Naito, T.; Terunuma, N.; Urakawa, J.; Zimmermann, F.

    1998-06-01

    The purpose of the ATF damping ring is the development of technologies for producing a low emittance beam required in future linear colliders such as JLC. The lifetime of the damping ring is very short (typically a few minutes). It is limited by elastic beam-gas scattering along with a small dynamic aperture, and by single intra-beam scattering (Touschek effect). The Touschek lifetime strongly depends upon the charge density of the beam, especially, the size of the vertical emittance. In this paper, the authors report the results of beam lifetime measurements in the ATF damping ring and the estimation of the vertical emittance from these measurements

  12. Lifetime of B hadrons from CDF

    International Nuclear Information System (INIS)

    Miao, Ting.

    1996-08-01

    A review of the lifetimes of B hadrons measured by the CDF collaboration at Fermilab is presented. The data corresponds to 110 pb -1 of p anti p collisions at √s = 1.8 TeV. The inclusive B hadron lifetime is measured using a high statistics sample of B → J/ΨΧ decays. Species specific lifetimes of the B + , B 0 , B 0 s , and Λ 0 b are determined using both fully reconstructed decays and partially reconstructed decays consisting of a lepton associated with a charm hadron

  13. Models for Battery Reliability and Lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.; Wood, E.; Santhanagopalan, S.; Kim, G. H.; Neubauer, J.; Pesaran, A.

    2014-03-01

    Models describing battery degradation physics are needed to more accurately understand how battery usage and next-generation battery designs can be optimized for performance and lifetime. Such lifetime models may also reduce the cost of battery aging experiments and shorten the time required to validate battery lifetime. Models for chemical degradation and mechanical stress are reviewed. Experimental analysis of aging data from a commercial iron-phosphate lithium-ion (Li-ion) cell elucidates the relative importance of several mechanical stress-induced degradation mechanisms.

  14. Statistical Models and Methods for Lifetime Data

    CERN Document Server

    Lawless, Jerald F

    2011-01-01

    Praise for the First Edition"An indispensable addition to any serious collection on lifetime data analysis and . . . a valuable contribution to the statistical literature. Highly recommended . . ."-Choice"This is an important book, which will appeal to statisticians working on survival analysis problems."-Biometrics"A thorough, unified treatment of statistical models and methods used in the analysis of lifetime data . . . this is a highly competent and agreeable statistical textbook."-Statistics in MedicineThe statistical analysis of lifetime or response time data is a key tool in engineering,

  15. Study on lifetime of C stripping foils

    International Nuclear Information System (INIS)

    Zhang Hongbin; Lu Ziwei; Zhao Yongtao; Li Zhankui; Xu Hushan; Xiao Guoqing; Wang Yuyu; Zhang Ling; Li Longcai; Fang Yan

    2007-01-01

    The carbon stripping foils can be prepared with the AC and DC arc discharge methods, or even sandwiched with AC-DC alternative layers. The lifetime of the carbon stripping foils of 19 μg/cm 2 prepared with different methods and/or structures was measured. The factors affecting the bombarding lifetime of the carbon stripping foils, especially the method of the foil preparation and the structure of the carbon stripping foils, were discussed. It is observed that the foils prepared with the DC arc discharge method have a longer bombarding lifetime than those prepared with the AC arc discharge method. (authors)

  16. Photoluminescence decay lifetime measurements of hemicyanine derivatives of different alkyl chain lengths

    International Nuclear Information System (INIS)

    Shim, Taekyu; Lee, Myounghee; Kim, Sungho; Sung, Jaeho; Rhee, Bum Ku; Kim, Doseok; Kim, Hyunsung; Yoon, Kyung Byung

    2004-01-01

    The fluorescence upconversion setup for the detection of photoluminescence (PL) decay lifetime with subpicosecond time resolution was constructed, and the photoluminescence phenomena of several hemicyanine dyes with alkyl chains of different chain lengths tethered to the N atom of the pyridine moiety (HC-n, n=6, 15, 22) in methanol were investigated. The average decay lifetimes of the solutions determined from the measured data by multi-order exponential decay curve fitting were ∼27 ps at the PL peak wavelength. It was found that the PL decay properties did not depend on the alkyl chain length in the molecule, implying that the twist of the alkylpyridinium ring of the molecule is not possible as a nonfluorescing relaxation pathway. The time-dependent PL spectra constructed from the PL lifetime data showed the dynamic Stokes shift of ∼1000 cm -1

  17. Lifetimes of partial charge transfer exciplexes of 9-cyanophenanthrene and 9-cyanoanthracene

    OpenAIRE

    Dolotova, Elena; Dogadkin, Denis; Soboleva, Irina; Kuzmin, Michael; Nicolet, Olivier; Vauthey, Eric

    2003-01-01

    The fluorescence decays of several exciplexes with partial charge transfer have been investigated in solvents of various polarity. The measured lifetimes are found to be in reasonable agreement with the activation enthalpy and entropy of exciplex decay obtained earlier from the temperature dependence of the exciplex emission quantum yields. For exciplexes with 9-cyanophenanthrene substantial contribution of the higher local excited state into the exciplex electronic structure is found and bor...

  18. Origins of fluorescence in evolved bacteriophytochromes.

    Science.gov (United States)

    Bhattacharya, Shyamosree; Auldridge, Michele E; Lehtivuori, Heli; Ihalainen, Janne A; Forest, Katrina T

    2014-11-14

    Use of fluorescent proteins to study in vivo processes in mammals requires near-infrared (NIR) biomarkers that exploit the ability of light in this range to penetrate tissue. Bacteriophytochromes (BphPs) are photoreceptors that couple absorbance of NIR light to photoisomerization, protein conformational changes, and signal transduction. BphPs have been engineered to form NIR fluorophores, including IFP1.4, Wi-Phy, and the iRFP series, initially by replacement of Asp-207 by His. This position was suggestive because its main chain carbonyl is within hydrogen-bonding distance to pyrrole ring nitrogens of the biliverdin chromophore, thus potentially functioning as a crucial transient proton sink during photoconversion. To explain the origin of fluorescence in these phytofluors, we solved the crystal structures of IFP1.4 and a comparison non-fluorescent monomeric phytochrome DrCBDmon. Met-186 and Val-288 in IFP1.4 are responsible for the formation of a tightly packed hydrophobic hub around the biliverdin D ring. Met-186 is also largely responsible for the blue-shifted IFP1.4 excitation maximum relative to the parent BphP. The structure of IFP1.4 revealed decreased structural heterogeneity and a contraction of two surface regions as direct consequences of side chain substitutions. Unexpectedly, IFP1.4 with Asp-207 reinstalled (IFPrev) has a higher fluorescence quantum yield (∼9%) than most NIR phytofluors published to date. In agreement, fluorescence lifetime measurements confirm the exceptionally long excited state lifetimes, up to 815 ps, in IFP1.4 and IFPrev. Our research helps delineate the origin of fluorescence in engineered BphPs and will facilitate the wide-spread adoption of phytofluors as biomarkers. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Long term optical stability of fluorescent solar concentrator plates

    NARCIS (Netherlands)

    Slooff, L.H.; Bakker, N.J.; Sommeling, P.M.; Büchtemann, A.; Wedel, A.; Sark, W.G.J.H.M. van

    2014-01-01

    Fluorescent solar concentrators offer an alternative approach for low-cost photovoltaic energy conversion. For successful application, not only the power conversion efficiency and cost are important, but also lifetime or stability of the devices. As today’s concentrator is made of polymer sheets

  20. Long-term optical stability of fluorescent solar concentrator plates

    NARCIS (Netherlands)

    Slooff, Lenneke H.; Bakker, Nicolaas J.; Sommeling, Paul M.; Büchtemann, Andreas; Wedel, Armin; Van Sark, Wilfried G J H M

    2014-01-01

    Fluorescent solar concentrators offer an alternative approach for low-cost photovoltaic energy conversion. For successful application, not only the power conversion efficiency and cost are important, but also lifetime or stability of the devices. As today's concentrator is made of polymer sheets

  1. RDM lifetime measurements in 187Tl

    International Nuclear Information System (INIS)

    Chamoli, S.K.; Joshi, P.; Kumar, A.; Govil, I.M.; Mukherjee, G.; Singh, R.P.; Muralithar, S.; Bhowmik, R.K.

    2003-01-01

    The present work is an attempt to study the shape changes in 187 Tl through a measurement of electromagnetic transition probabilities of the high spin states. The Doppler shifted recoil distance technique was used to measure the lifetimes

  2. Improved b lifetime measurement from MAC

    International Nuclear Information System (INIS)

    Ford, W.T.

    1984-03-01

    Two recent publications, from the MAC and Mark II collaborations, have reported the somewhat surprising result that the lifetime of particles made up of b quarks is in the 1 to 2 picosecond range, or somewhat longer than the lifetimes of charm particles. Although the charm decays are favored transitions while those of b particles depend upon off-diagonal elements of the weak flavor mixing matrix, the smallness of the b decay rates in face of the large available phase space indicates that the off-diagonal elements are indeed very small. The possibility for complete determination of the mixing matrix was brought significantly nearer by the availability of the lifetime information; what is needed now is to reduce the uncertainty of the measurements, which was about 33% for both experiments. We describe here an extension of the b lifetime study with the MAC detector, incorporating some new data and improvements in the analysis. 12 references

  3. Lifetime measurements of excited Co I levels

    CERN Document Server

    Klotz, W D; Gobel, L H

    1977-01-01

    In the region of 3500 AA the lifetimes of eight excited Cobalt I levels have been measured by means of the zero field level crossing method. The measured lifetimes belong to the odd configurations 3d/sup 7/4s4p and 3d/sup 8/4p and are of the accuracy of about 5%. The hyperfine structure of levels with I not=J has to be taken into account in evaluating lifetimes from level crossing data, because the nuclear spin of the natural isotope /sup 59/Co is I=7/2. Therefore the influence of the line profile of the exciting resonance lines on the lifetimes has been investigated. The results are compared with those of other authors. Furthermore absolute oscillator strengths were calculated with known branching ratios and a new absolute scale has been established. (23 refs).

  4. Quantum lifetime in electron storage rings

    International Nuclear Information System (INIS)

    Chao, A.W.

    1977-02-01

    One of the mechanisms which contribute to beam lifetime in electron storage rings is the quantum emission of energetic photons causing particles to be lost from the rf bucket. This quantum lifetime is among other things important in defining the required aperture in a storage ring. An approximate expression of quantum lifetime, predicted by a one-dimensional model which takes into account only the betatron motion, has been used in most storage ring designs. If the beam is aperture-limited at a position with nonzero dispersion, both the betatron and synchrotron motions have to be included and a two-dimensional model must be used. An exact expression of quantum lifetime for the one-dimensional case and an approximate expression for the two-dimensional case are given

  5. Quantum lifetime in electron storage rings

    International Nuclear Information System (INIS)

    Chao, A.W.

    1977-01-01

    One of the mechanisms which contributes to beam lifetime in electron storage rings is the quantum emission of energetic photons causing particles to be lost from the rf bucket. This quantum lifetime is among other things important in defining the required aperture in a storage ring. An approximate expression of quantum lifetime, predicted by a one-dimensional model which takes into account only the betatron motion, has been used in most storage ring designs. If the beam is aperture-limited at a position with nonzero dispersion, both the betatron and synchrotron motions have to be included, and a two-dimensional model must be used. An exact expression of quantum lifetime for the one-dimensional case and an approximate expression for the two-dimensional case are given

  6. Lifetime measurements of hadrons containing heavy quarks

    International Nuclear Information System (INIS)

    Forden, G.E.

    1985-01-01

    Recent lifetime measurements of heavy particles at PETRA and PEP are reviewed. A comparison of the methods used is given. The world averages for the lifetimes of the D 0 and D +- mesons are found to be (tau/dub D/ 0 ) - 3.97 +/- 0.3 x 10 -13 sec and (tau/dub D +-/) = 8.6 +/- 0.7 x 10 -13 sec. This difference in lifetimes is discussed in light of recent information about exclusive decays. The world average for the lifetime of bottom hadrons is determined to be (tau/sub b/) = 11.0 +/- 1.5 x 10 -13 sec and new estimates for the b quark mixing elements, absolute value V/sub bu/ and absolute value V/sub bc/, are given

  7. The Impact of a 15-Week Lifetime Wellness Course on Behavior Change and Self-Efficacy in College Students

    Science.gov (United States)

    Lockwood, Park; Wohl, Roy

    2012-01-01

    Purpose: The purpose of this study was to assess the effectiveness of a lifetime wellness course on changing students' global self-efficacy, physical self-efficacy, and wellness behavior. Methods: Seventy-one college students from a lifetime wellness course completed the TestWell Wellness Inventory--Standard Edition (National Wellness Institute,…

  8. Lifetime measurement in {sup 195}Po

    Energy Technology Data Exchange (ETDEWEB)

    Grahn, T.; Page, R.D. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Dewald, A.; Jolie, J.; Melon, B.; Pissulla, T. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Greenlees, P.T.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Peura, P.; Rahkila, P.; Saren, J.; Scholey, C.; Sorri, J.; Uusitalo, J. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, Jyvaeskylae (Finland); Kroell, T.; Kruecken, R.; Maierbeck, P. [TU Muenchen, Physik-Department E12, Garching (Germany)

    2009-03-15

    The lifetime of the 17/2{sup +} yrast state in {sup 195}Po has been measured using the recoil distance Doppler-shift technique to be {tau}=43(11) ps. The lifetime was extracted from the singles {gamma}-ray spectra obtained by using the recoil-decay tagging method. The present work provides more information of the coupling schemes, shapes and configuration mixing in neutron-deficient odd-mass Po nuclei. (orig.)

  9. The measurement of subnanosecond nuclear lifetimes

    International Nuclear Information System (INIS)

    White, D.C.S.

    1974-01-01

    This research dealt with the measurement of subnanosecond nuclear lifetimes using the pulsed beam delayed-coincidence technique. Measurements were performed on isotopes in the f7/2 shell and specifically the isotopes of titanium and vanadium. Experimental investigations were also pursued in 59 Ni and 65 Zn. Several new lifetimes were determined and confirmation was obtained for some previous values which were measured with different techniques. More information was also obtained on certain levels where previous results are in disagreement. (author)

  10. Masses and lifetimes of B hadrons

    International Nuclear Information System (INIS)

    Kkkroll, I.J.

    1996-02-01

    The latest measurements of the masses and lifetimes of weakly decaying B hadrons from experiments at e + e - and p bar p colliders are presented. These measurements include the lifetimes of the bar B o , bar B o s , B - and b baryons, as well as searches for the B c meson. The observation of B*, p-wave B mesons (B**), and excited b baryons using inclusive and exclusive B hadron reconstruction are discussed. Results on b quark flavour tagging are given

  11. Λc photoproduction and lifetime measurement

    International Nuclear Information System (INIS)

    Amendolia, S.R.; Bagliesi, G.; Batignani, G.; Bertolucci, E.; Bettoni, D.; Bizetti, A.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giannetti, P.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Raso, G.; Ristori, L.; Scribano, A.; Stefanini, A.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Beck, G.A.; Bologna, G.; D'Ettorre Piazzoli, B.; Picchi, P.; Budinich, M.; Liello, F.; Milotti, E.; Rolandi, L.; Carter, J.; Green, M.G.; Landon, M.P.J.; March, P.V.; Sacks, L.; Sanjari, A.H.; Strong, J.A.; Ciocci, M.A.; Enorini, M.; Fabbri, F.L.; Laurelli, P.; Mannocchi, G.; Simonelli, L.; Spillantini, P.; Zallo, A.

    1987-01-01

    A measurement of the lifetime of the Λ c baryon photoproduced coherently of a germanium-silicon target is presented. A signal of Λ c → ΔΚ * → pKππ 0 has been observed and the two different decay diagrams for this process are compared. A sample of 9 Λ c decays give a lifetime of 1.1(+0.8-0.4)10 13 s. (orig.)

  12. Measurement of the Omega0(c) lifetime

    International Nuclear Information System (INIS)

    Iori, M.

    2007-01-01

    The authors report a precise measurement of the (Omega) c 0 lifetime. The data were taken by the SELEX (E781) experiment using 600 GeV/c Σ - , π - and p beams. The measurement has been made using 83 ± 19 reconstructed (Omega) c 0 in the (Omega) - π - π + π + and (Omega) - π + decay modes. The lifetime of the (Omega) c 0 is measured to be 65 ± 13(stat) ± 9(sys) fs

  13. The total lifetime costs of smoking

    DEFF Research Database (Denmark)

    Rasmussen, S.R.; Prescott, E.; Sørensen, T.I.A.

    2004-01-01

    Net costs of smoking in a lifetime perspective and, hence, the economic interests in antismoking policies have been questioned. It has been proposed that the health-related costs of smoking are balanced by smaller expenditure due to shorter life expectancy.......Net costs of smoking in a lifetime perspective and, hence, the economic interests in antismoking policies have been questioned. It has been proposed that the health-related costs of smoking are balanced by smaller expenditure due to shorter life expectancy....

  14. Positron lifetime studies on thorium oxide powders

    International Nuclear Information System (INIS)

    Upadhyaya, D.D.; Muraleedharan, R.V.; Sharma, B.D.

    1982-01-01

    Positron lifetime spectra have been studied for ThO 2 powders, calcined at different temperatures and having different particle sizes. Three lifetime components could be resolved, the longest component being of low intensity. An observed strong dependence on the particle size of the annihilation process and the variation of positronium diffusion constant is explained on the basis of defect density variations in these powders. (author)

  15. Lifetimes of charm and beauty hadrons

    International Nuclear Information System (INIS)

    Bellini, G.; Dornan, P.J.

    1997-01-01

    Major breakthroughs have been achieved in the determination of the lifetimes of charm and beauty hadrons. Much larger data samples than previously have become available and new experimental devices and techniques have been developed and employed. The lifetimes of all weakly decaying singly charmed hadrons have been measured, some with an accuracy of a few percent. The difference in the shortest lifetime - τ(Ω c ) - and the longest one - τ(D + ) - is given by a factor of close to ten. The experimental status of beauty lifetimes, while less complete, has still reached a new level of quality and is now better than 5% for the commoner states. New theoretical tools, based mainly on heavy quark expansions, have been developed; they incorporate as well as transcend earlier phenomenological descriptions. The observed pattern in the charm lifetime ratios is reproduced in a semi-quantitative manner as well as could be expected; as far as the beauty lifetime ratios are concerned some problems may well be emerging. The maturity level achieved in the measurements bodes quite well for future challenges where reliable and efficient tracking of the decay vertices will be crucial. (orig.)

  16. Methods for the analysis of complex fluorescence decays: sum of Becquerel functions versus sum of exponentials

    International Nuclear Information System (INIS)

    Menezes, Filipe; Fedorov, Alexander; Baleizão, Carlos; Berberan-Santos, Mário N; Valeur, Bernard

    2013-01-01

    Ensemble fluorescence decays are usually analyzed with a sum of exponentials. However, broad continuous distributions of lifetimes, either unimodal or multimodal, occur in many situations. A simple and flexible fitting function for these cases that encompasses the exponential is the Becquerel function. In this work, the applicability of the Becquerel function for the analysis of complex decays of several kinds is tested. For this purpose, decays of mixtures of four different fluorescence standards (binary, ternary and quaternary mixtures) are measured and analyzed. For binary and ternary mixtures, the expected sum of narrow distributions is well recovered from the Becquerel functions analysis, if the correct number of components is used. For ternary mixtures, however, satisfactory fits are also obtained with a number of Becquerel functions smaller than the true number of fluorophores in the mixture, at the expense of broadening the lifetime distributions of the fictitious components. The quaternary mixture studied is well fitted with both a sum of three exponentials and a sum of two Becquerel functions, showing the inevitable loss of information when the number of components is large. Decays of a fluorophore in a heterogeneous environment, known to be represented by unimodal and broad continuous distributions (as previously obtained by the maximum entropy method), are also measured and analyzed. It is concluded that these distributions can be recovered by the Becquerel function method with an accuracy similar to that of the much more complex maximum entropy method. It is also shown that the polar (or phasor) plot is not always helpful for ascertaining the degree (and kind) of complexity of a fluorescence decay. (paper)

  17. Delayed fluorescence of meso-tetraphenylporphyrin in acetone and in dimethylsulphoxide

    International Nuclear Information System (INIS)

    Korinek, M.; Klinger, P.; Dedic, R.; Psencik, J.; Svoboda, A.; Hala, J.

    2007-01-01

    Photodynamic therapy is based on photosensitisation of singlet oxygen by porphyrin-like molecules. We have performed a systematic study of delayed fluorescence of tetraphenylporphyrin in acetone (used as a spectroscopic standard) and in dimethylsulphoxide (clinically used solvent) to obtain spectra, kinetics, and quantum yields, including their dependencies on tetraphenylporphyrin concentration. In dimethylsulphoxide the repopulation of excited singlets and subsequent delayed fluorescence is caused by triplet-triplet quenching with rate constant of (2.2±1.0)x10 9 l mol -1 s -1 . However, repopulation of excited singlets in acetone is also caused by singlet oxygen reaction with triplet tetraphenylporphyrin causing monoexponential delayed fluorescence decay with the lifetime 0.3 μs. Due to much lower viscosity of acetone compared to dimethylsulphoxide, triplet-triplet quenching constant in acetone is much higher (1.7±0.7)x10 10 l mol -1 s -1 . The rate constant for the reaction of singlet oxygen with triplet of tetraphenylporphyrin is (2.0±0.8)x10 10 l mol -1 s -1 in acetone

  18. Plasmonics Enhanced Smartphone Fluorescence Microscopy

    KAUST Repository

    Wei, Qingshan; Acuna, Guillermo; Kim, Seungkyeum; Vietz, Carolin; Tseng, Derek; Chae, Jongjae; Shir, Daniel; Luo, Wei; Tinnefeld, Philip; Ozcan, Aydogan

    2017-01-01

    Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

  19. Plasmonics Enhanced Smartphone Fluorescence Microscopy

    KAUST Repository

    Wei, Qingshan

    2017-05-12

    Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

  20. Picosecond wide-field time-correlated single photon counting fluorescence microscopy with a delay line anode detector

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Le Marois, Alix; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Becker, Wolfgang; Smietana, Stefan [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Milnes, James; Conneely, Thomas [Photek Ltd., 26 Castleham Rd, Saint Leonards-on-Sea TN38 9NS (United Kingdom); Jagutzki, Ottmar [Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt (Germany)

    2016-08-15

    We perform wide-field time-correlated single photon counting-based fluorescence lifetime imaging (FLIM) with a crossed delay line anode image intensifier, where the pulse propagation time yields the photon position. This microchannel plate-based detector was read out with conventional fast timing electronics and mounted on a fluorescence microscope with total internal reflection (TIR) illumination. The picosecond time resolution of this detection system combines low illumination intensity of microwatts with wide-field data collection. This is ideal for fluorescence lifetime imaging of cell membranes using TIR. We show that fluorescence lifetime images of living HeLa cells stained with membrane dye di-4-ANEPPDHQ exhibit a reduced lifetime near the coverslip in TIR compared to epifluorescence FLIM.

  1. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  2. Multiwavelength FLIM: new concept for fluorescence diagnosis

    Science.gov (United States)

    Rück, Angelika; Lorenz, S.; Hauser, Carmen; Mosch, S.; Kalinina, S.

    2012-03-01

    Fluorescence guided tumor resection is very well accepted in the case of bladder cancer and brain tumor, respectively. However, false positive results are one of the major problems, which will make the discrimination between tumor tissue and inflammation difficult. In contrast fluorescence lifetime imaging (FLIM) and especially spectral resolved FLIM (SLIM) can significantly improve the analysis. The fluorescence decay of a fluorophore in many cases does not show a simple monoexponential profile. A very complex situation arises, when more than one compound has to be analyzed. This could be the case when endogenous fluorophores of living cells and tissues have to be discriminated to identify oxidative metabolic changes. Other examples are PDT, when different photosensitizer metabolites are observed simultaneously. In those cases a considerable improvement could be achieved when time-resolved and spectral-resolved techniques are simultaneously incorporated. Within this presentation the principles of spectral and time-resolved fluorescence imaging will be discussed. Successful applications as autofluorescence and 5-ALA induced porphyrin fluorescence will be described in more detail.

  3. ConA-based glucose sensing using the long-lifetime azadioxatriangulenium fluorophore

    Science.gov (United States)

    Cummins, Brian; Simpson, Jonathan; Gryczynski, Zygmunt; Sørensen, Thomas Just; Laursen, Bo W.; Graham, Duncan; Birch, David; Coté, Gerard

    2014-02-01

    Fluorescent glucose sensing technologies have been identified as possible alternatives to current continuous glucose monitoring approaches. We have recently introduced a new, smart fluorescent ligand to overcome the traditional problems of ConA-based glucose sensors. For this assay to be translated into a continuous glucose monitoring device where both components are free in solution, the molecular weight of the smart fluorescent ligand must be increased. We have identified ovalbumin as a naturally-occurring glycoprotein that could serve as the core-component of a 2nd generation smart fluorescent ligand. It has a single asparagine residue that is capable of displaying an N-linked glycan and a similar isoelectric point to ConA. Thus, binding between ConA and ovalbumin can potentially be monovalent and sugar specific. This work is the preliminary implementation of fluorescently-labeled ovalbumin in the ConA-based assay. We conjugate the red-emitting, long-lifetime azadioxatriangulenium (ADOTA+) dye to ovalbumin, as ADOTA have many advantageous properties to track the equilibrium binding of the assay. The ADOTA-labeled ovalbumin is paired with Alexa Fluor 647-labeled ConA to create a Förster Resonance Energy Transfer (FRET) assay that is glucose dependent. The assay responds across the physiologically relevant glucose range (0-500 mg/dL) with increasing intensity from the ADOTA-ovalbumin, showing that the strategy may allow for the translation of the smart fluorescent ligand concept into a continuous glucose monitoring device.

  4. Plant lifetime management at Jose Cabrera NPP

    International Nuclear Information System (INIS)

    Martin, Jorge; Garcia, Piedad

    1998-01-01

    This paper presents the results obtained during the development and implementation of the Jose Cabrera NPP Lifetime Management Program according to the methodology applied in the Plant. The implementation of the Lifetime Management Program began in 1995 with the elaboration of the annual revision document 'Lifetime Management Plan', which describes the level of development of the Lifetime Management activities, the results that have been obtained during the implementation of the Program, and the schedule of the upcoming activities. The drawing up of a weighted list of 135 important components and the elaboration of 17 dossiers integrating the ageing mechanisms analysis and its corresponding evaluation, control and mitigation methods, were the result of the activities completed during 1996. A group of 62 component/degradation phenomena pairs with a high degradation risk classification has been considered within the scope of the activity 'Assessment of Maintenance Practices. Improvement Proposal', performed by the plant during 1997 and the first term of 1998 in parallel with other Lifetime Management related activities. The results obtained within this activity have revealed for the components included in the scope of the assessment that the associated degradation phenomena are practically covered by the current maintenance, inspection and testing practices. Recommendations and improvements of the maintenance practices have been particularly proposed from a technical, supporting, proceeding and documentary point of view, and currently an analysis is being made in relation to the feasibility of implementing them at the Jose Cabrera NPP. (author)

  5. Positron lifetime studies of electron irradiated copper

    International Nuclear Information System (INIS)

    Hadnagy, T.D.

    1976-01-01

    Single-crystal copper was irradiated with 4.5-MeV electrons producing simple Frenkel defects as well as a significant concentration of divacancies. Mean positron lifetime characteristics, which are sensitive to the presence of vacancies and multivacancies in copper, was monitored after isochronal anneals between 80 and 800 0 K to determine the relative change of characteristic mean lifetimes and their associated intensities. Also a study of the dependence of the mean positron lifetime on the total electron fluence was made and compared with existing theories relating these lifetimes to vacancy or multivacancy concentrations. Numerical data from curve fitting procedures using a conventional trapping model for defect-induced changes in positron lifetimes indicate that upon irradiation with 4.5-MeV electrons at 80 0 K, about 8 percent of the defects produced are divacancy units. Divacancy units appear to be several times more effective in trapping positrons than are monovacancies. Further, the experimental data suggest that the stage III annealing processes in electron-irradiated copper most probably involve the motion and removal of both monovacancies and divacancies. A conglomerate (multivacancy) unit appears to exist as a stable entity even after annealing procedures are carried out at temperatures slightly above the stage III region. Such a stable unit could serve as a nucleation center for the appearance of voids

  6. Prenatal alcohol use: the role of lifetime problems with alcohol, drugs, depression, and violence.

    Science.gov (United States)

    Flynn, Heather A; Chermack, Stephen T

    2008-07-01

    The purpose of this study was to examine a broader array of lifetime factors that theoretically may be associated with prenatal alcohol use than have previously been studied together, including family history of alcohol-use problems, history of physical or sexual abuse, lifetime major depressive disorder, alcohol-use disorder, illicit-drug-use problems, and partner violence. A total of 186 pregnant women, all of whom used alcohol in the year before pregnancy, were initially recruited in prenatal care settings. Women who reported no prenatal alcohol use (n = 96) were compared with women who drank 1-10 standard drinks during pregnancy (n = 75) and with women who drank more than 10 standard drinks during pregnancy (n = 13), considered to be a higher risk group, on the lifetime risk variables. Because of the public health implications, secondary analyses compared women who abstained during pregnancy with those who used any alcohol. Significant intercorrelations were found among most of the lifetime risk factors studied. Multivariate analyses showed that drug-use problems and partner violence were most strongly associated with prenatal alcohol use than any other variable studied. Consistent with a life span risk framework for alcohol-use problems, results of this study show that childhood abuse, familial alcoholism, lifetime major depressive disorder, and alcohol- and drug-use problems are interrelated. However, when considered together, only lifetime partner violence and drug use are significantly related to various levels of prenatal alcohol use. Identification, assessment, and intervention efforts should integrate these important factors.

  7. FastFLIM, the all-in-one engine for measuring photoluminescence lifetime of 100 picoseconds to 100 milliseconds

    Science.gov (United States)

    Sun, Yuansheng; Coskun, Ulas; Liao, Shih-Chu Jeff; Barbieri, Beniamino

    2018-02-01

    Photoluminescence (PL) refers to light emission initiated by any form of photon excitation. PL spectroscopy and microscopy imaging has been widely applied in material, chemical and life sciences. Measuring its lifetime yields a new dimension of the PL imaging and opens new opportunities for many PL applications. In solar cell research, quantification of the PL lifetime has become an important evaluation for the characteristics of the Perovskite thin film. Depending upon the PL process (fluorescence, phosphorescence, photon upconversion, etc.), the PL lifetimes to be measured can vary in a wide timescale range (e.g. from sub-nanoseconds to microseconds or even milliseconds) - it is challenging to cover this wide range of lifetime measurements by a single technique efficiently. Here, we present a novel digital frequency domain (DFD) technique named FastFLIM, capable of measuring the PL lifetime from 100 ps to 100 ms at the high data collection efficiency (up to 140-million counts per second). Other than the traditional nonlinear leastsquare fitting analysis, the raw data acquired by FastFLIM can be directly processed by the model-free phasor plots approach for instant and unbiased lifetime results, providing the ideal routine for the PL lifetime microscopy imaging.

  8. Analyzing the factors affecting network lifetime cluster-based wireless sensor network

    International Nuclear Information System (INIS)

    Malik, A.S.; Qureshi, A.

    2010-01-01

    Cluster-based wireless sensor networks enable the efficient utilization of the limited energy resources of the deployed sensor nodes and hence prolong the node as well as network lifetime. Low Energy Adaptive Clustering Hierarchy (Leach) is one of the most promising clustering protocol proposed for wireless sensor networks. This paper provides the energy utilization and lifetime analysis for cluster-based wireless sensor networks based upon LEACH protocol. Simulation results identify some important factors that induce unbalanced energy utilization between the sensor nodes and hence affect the network lifetime in these types of networks. These results highlight the need for a standardized, adaptive and distributed clustering technique that can increase the network lifetime by further balancing the energy utilization among sensor nodes. (author)

  9. Lifetime of heavy hypernuclei and its implications on the weak LAMBDA N interaction

    CERN Document Server

    Cassing, W; Kamys, B; Kulessa, P; Niewodniczanski, H; Ohm, H; Pysz, K; Rudy, Z; Schult, O W B; Ströher, H

    2003-01-01

    The lifetime of the LAMBDA-hyperon in heavy hypernuclei measured in proton-Au, -Bi and -U collisions by the COSY-13 Collaboration at COSY-Juelich has been analyzed to yield tau subLAMBDA=(145+-11) ps. This value for tau subLAMBDA is compatible with the lifetime extracted from antiproton annihilation on Bi and U targets, albeit much more accurate. Theoretical models based on the meson exchange picture and assuming the validity of the phenomenological DELTA I=1/2 rule predict the lifetime of heavy hypernuclei to be significantly larger (2-3 standard deviations). Such large differences indicate that at least one of the assumptions in these models is not fulfilled. A much better reproduction of the lifetimes of heavy hypernuclei is achieved in the phase space model, if the DELTA I=1/2 rule is discarded in the nonmesonic LAMBDA decay. (orig.)

  10. Lifetime of heavy hypernuclei and its implications on the weak ΛN interaction

    International Nuclear Information System (INIS)

    Cassing, W.; Jarczyk, L.; Kamys, B.; Kulessa, P.; Pysz, K.; Ohm, H.; Schult, O.W.B.; Stroeher, H.; Rudy, Z.

    2003-01-01

    The lifetime of the Λ-hyperon in heavy hypernuclei measured in proton-Au, -Bi and -U collisions by the COSY-13 Collaboration at COSY-Juelich has been analyzed to yield τ Λ =(145±11) ps. This value for τ Λ is compatible with the lifetime extracted from antiproton annihilation on Bi and U targets, albeit much more accurate. Theoretical models based on the meson exchange picture and assuming the validity of the phenomenological ΔI=1/2 rule predict the lifetime of heavy hypernuclei to be significantly larger (2-3 standard deviations). Such large differences indicate that at least one of the assumptions in these models is not fulfilled. A much better reproduction of the lifetimes of heavy hypernuclei is achieved in the phase space model, if the ΔI=1/2 rule is discarded in the nonmesonic Λ decay. (orig.)

  11. Improved lifetime of microchannel-plate PMTs

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, A., E-mail: lehmann@physik.uni-erlangen.de [Physikalisches Institut IV, Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); Britting, A.; Eyrich, W.; Uhlig, F. [Physikalisches Institut IV, Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Höhler, R.; Kalicy, G.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); and others

    2014-12-01

    The charged particle identification at the PANDA experiment will be mainly performed with DIRC detectors. Because of their advantageous properties the preferred photon sensors are MCP-PMTs. However, until recently these devices showed serious aging problems which resulted in a diminishing quantum efficiency (QE) of the photo cathode. By applying innovative countermeasures against the aging causes, the manufacturers recently succeeded in drastically improving the lifetime of MCP-PMTs. Especially the application of an ALD coating technique to seal the material of the micro-channels proves very powerful and results in a lifetime of ≈6C/cm{sup 2} integrated anode charge without a substantial QE degradation for the latest PHOTONIS XP85112. This paper will present a comparative measurement of the lifetime of several older and recent MCP-PMTs demonstrating this progress.

  12. Measurement of the $\\tau$ lepton lifetime

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Garrido, L; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Fidecaro, F; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    The mean lifetime of the \\tau lepton is measured in a sample of 25700 \\tau pairs collected in 1992 with the ALEPH detector at LEP. A new analysis of the 1-1 topology events is introduced. In this analysis, the dependence of the impact parameter sum distribution on the daughter track momenta is taken into account, yielding improved precision compared to other impact parameter sum methods. Three other analyses of the one- and three-prong \\tau decays are updated with increased statistics. The measured lifetime is 293.5 \\pm 3.1 \\pm 1.7 \\fs. Including previous (1989--1991) ALEPH measurements, the combined \\tau lifetime is 293.7 \\pm 2.7 \\pm 1.6 \\fs.

  13. Lifetime for the Ti X spectrum

    International Nuclear Information System (INIS)

    Singh, Jagjit; Jha, A K S; Mohan, M

    2010-01-01

    We present configuration interaction calculations for the lifetime of 294 fine-structure levels of the Ti X spectrum in the LSJ coupling scheme. The calculations include all the major correlation effects. The relativistic effects are included by adding the mass correction term, Darwin term and spin-orbit interaction term to the non-relativistic Hamiltonian in the Breit-Pauli approximation. The calculated lifetime values are in very close agreement with other available experimental and theoretical results. We have predicted new lifetime results for levels belonging to 3p 2 3d, 3s 2 4p, 3s3p4s, 3s3p4p and various other configurations of Ti X, where no other theoretical and experimental results are available.

  14. Reviews in fluorescence 2008

    CERN Document Server

    Geddes, Chris D

    2010-01-01

    This volume serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence spectroscopy. It summarizes the year's progress in fluorescence and its applications as well as includes authoritative analytical reviews.

  15. Fluorescent optical position sensor

    Science.gov (United States)

    Weiss, Jonathan D.

    2005-11-15

    A fluorescent optical position sensor and method of operation. A small excitation source side-pumps a localized region of fluorescence at an unknown position along a fluorescent waveguide. As the fluorescent light travels down the waveguide, the intensity of fluorescent light decreases due to absorption. By measuring with one (or two) photodetectors the attenuated intensity of fluorescent light emitted from one (or both) ends of the waveguide, the position of the excitation source relative to the waveguide can be determined by comparing the measured light intensity to a calibrated response curve or mathematical model. Alternatively, excitation light can be pumped into an end of the waveguide, which generates an exponentially-decaying continuous source of fluorescent light along the length of the waveguide. The position of a photodetector oriented to view the side of the waveguide can be uniquely determined by measuring the intensity of the fluorescent light emitted radially at that location.

  16. Vibrational lifetimes of protein amide modes

    International Nuclear Information System (INIS)

    Peterson, K.A.; Rella, C.A.

    1995-01-01

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid

  17. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I [Berkeley, CA; Fergenson, David P [Alamo, CA; Srivastava, Abneesh [Santa Clara, CA; Bogan, Michael J [Dublin, CA; Riot, Vincent J [Oakland, CA; Frank, Matthias [Oakland, CA

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  18. Permeability log using new lifetime measurements

    International Nuclear Information System (INIS)

    Dowling, D.J.; Boyd, J.F.; Fuchs, J.A.

    1975-01-01

    Comparative measurements of thermal neutron decay time are obtained for a formation after irradiation with a pulsed neutron source. Chloride ions in formation fluids are concentrated by the electrosmosis effect using charged poles on a well logging sonde. The formation is irradiated with fast neutrons and a first comparative measure of the thermal neutron decay time or neutron lifetime is taken. The chloride ions are then dispersed by acoustic pumping with a magnetostrictive transducer. The formation is then again irradiated with fast neutrons and a comparative measure of neutron lifetime is taken. The comparison is a function of the variation in chloride concentration between the two measurements which is related to formation permeability

  19. An approach for longer lifetime MCFCs

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Masaru; Tatsumi, Masahiko; Hayano, Takuro [MCFC Research Association, Tokyo (Japan)] [and others

    1996-12-31

    For entering into commercialization of MCFC power plants in the beginning of the 21st century, we will devote to research for increasing lifetime as long as 40,000 hours with cell performance decay rate of 0.25 %/1000hrs as the target in FY 1999. This paper will discuss on our approach for longer lifetime MCFCs through electrolyte-loss management and NiO precipitation management as well as micro-structural control of electrodes and matrix plates. Cell voltage decay rate will be estimated by simulation through series of experiments on accelerated conditions.

  20. Lifetimes of some b-flavored hadrons

    International Nuclear Information System (INIS)

    Stone, S.

    2014-06-01

    Recent measurements of lifetimes of some b-flavored hadrons are presented and interpreted in the context of theoretical models, especially the Heavy Quark Expansion. Decay widths and decay width differences in the B s 0 - B-bar s 0 system are discussed from the studies of decays into the final states J/ψK + K - , J/ψπ + π - , D s + D s - , K + K - and D s ± π ± . Lifetime measurements of the baryons Λ b 0 , Ξ b - , Ξ b 0 , and Ω b - are also shown. (author)

  1. Positron lifetime in vanadium oxide bronzes

    International Nuclear Information System (INIS)

    Dryzek, J.; Dryzek, E.

    2003-01-01

    The positron lifetime (PL) and Doppler broadening (DB) of annihilation line measurements have been performed in vanadium oxide bronzes M x V 2 O 5 . The dependence of these annihilation characteristics on the kind and concentration of the metal M donor has been observed. In the PL spectrum only one lifetime component has been detected in all studied bronzes. The results indicate the positron localization in the structural tunnels present in the crystalline lattice of the vanadium oxide bronzes. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Quantum system lifetimes and measurement perturbations

    International Nuclear Information System (INIS)

    Najakov, E.

    1977-05-01

    The recently proposed description of quantum system decay in terms of repeated measurement perturbations is modified. The possibility of retarded reductions to a unique quantum state, due to ineffective localization of the decay products at initial time measurements, is simply taken into account. The exponential decay law is verified again. A modified equation giving the observed lifetime in terms of unperturbed quantum decay law, measurement frequency and reduction law is derived. It predicts deviations of the observed lifetime from the umperturbed one, together with a dependence on experimental procedures. The influence of different model unperturbed decay laws and reduction laws on this effect is studied

  3. Extension of the nuclear power plant lifetime

    International Nuclear Information System (INIS)

    Keramsi, Alain

    2011-01-01

    After a presentation of the French nuclear context (history of the reactor fleet, choice of reactor type, PWR operation principle, competitiveness, environmental performance), this Power Point presentation addresses the context and challenges of the operation lifetime (average fleet age in different countries, examples of extensions, case of the United States, what is at stake with lifetime extension, decennial visits, EDF strategy), discusses the EDF's safety objectives (definition of the three main safety functions, impact of the operation duration and of the coexistence of two generations for the safety functions), discusses how to manage the ageing phenomenon for replaceable and non-replaceable components

  4. Lifetime, money and cost-benefit analysis

    International Nuclear Information System (INIS)

    Bengtsson, G.

    1984-01-01

    The paper describes briefly many methods for explicit or implicit valuation of the loss of lifetime expectancy due to radiation exposures or other hazards. The health gain from investment in protection is compared with the health gain from a general increase in wealth. It is concluded that in many instances lifetime is valued at 1 to 10 times the gross national product produced in this time. This seems to be reasonable for rich countries whereas it may be questionable for poorer countries. Here, any investment that raises the level of living of the poorer segment of the population may have a greater effect on life expectancy. (author)

  5. Lifetimes for some excited states of sodium

    International Nuclear Information System (INIS)

    Thomas, P.; Campos, J.

    1979-01-01

    The lifetimes of some s,p and d levels of sodium have been measured by the delayed coincidence method, using a single-photon counting technique. The results are compared with the calculated values of the present work, and with other results. The lifetimes of the ns, np, and levels up to n10; of the nf levels up to n-9;and of the ng, nh,n1 and nk levels up to n-8, have been calculated and the transition probabilities of lines with origin in these levels are given. (Author) 38 refs

  6. Magnon lifetimes in terbium at low temperatures

    International Nuclear Information System (INIS)

    Bjerrum Moeller, H.; Mackintosh, A.R.

    1979-01-01

    The lifetimes of magnons propagating in the c-direction of Tb at 4.2 K have been measured by inelastic neutron scattering. In contrast to the behaviour at higher temperatures, where magnon-magnon scattering predominates, the broadening of the magnons increases towards the boundary of the single Brillouin zone, both in the acoustic and optical branches. This suggests that the scattering of the magnons by conduction electrons is important, and the observed lifetimes are consistent with a recent estimate of the magnitude of this effect. The acoustic magnons of very long wavelength behave anomalously, presumably due to dipolar interactions

  7. Measurement of the Bs0 lifetime

    Science.gov (United States)

    Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Martinez, M.; Mattison, T.; Orteu, S.; Pacheco, A.; Padilla, C.; Pascual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Girone, M.; Hagelberg, R.; Harvey, J.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Maggi, M.; Markou, C.; Mato, P.; Meinhard, H.; Minten, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Pater, J. R.; Perlas, J. A.; Perrodo, P.; Pusztaszeri, J.-F.; Ranjard, F.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Wachsmuth, H.; Wasserbaech, S.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Barres, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Johnson, S. D.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Fouque, G.; Passalacqua, L.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Moneta, L.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Levinthal, D.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Pepe-Altarelli, M.; Salomone, S.; Colrain, P.; Ten Have, I.; Knowles, I. G.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Thorn, S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Karger, C.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Hassard, J. F.; Lieske, N. M.; Moutoussi, A.; Nash, J.; Patton, S.; Payne, D. G.; Phillips, M. J.; San Martin, G.; Sedgbeer, J. K.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Vogl, R.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Walther, S. M.; Wanke, R.; Wolf, B.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Calvet, D.; Carr, J.; Coyle, P.; Diaconu, C.; Drinkard, J.; Etienne, F.; Nicod, D.; Payre, P.; Ross, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jakobs, K.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; Denis, R. St.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Janot, P.; Kimfn 19, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Musolino, G.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Valassi, A.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Gao, Y.; Green, M. G.; Johnson, D. L.; March, P. V.; Medcalf, T.; Mir, Ll. M.; Quazi, I. S.; Strong, J. A.; Bertin, V.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Babbage, W.; Booth, C. N.; Buttar, C.; Cartwright, S.; Combley, F.; Dawson, I.; Thompson, L. F.; Barberio, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Pitis, L.; Ragusa, F.; Bellantoni, L.; Chen, W.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Nachtman, J. M.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Shi, Z. H.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; Lan Wu, Sau; Wu, X.; Zheng, M.; Zobernig, G.; Aleph Collaboration

    1994-02-01

    The lifetime of the Bs0 has been measured in a data sample of 8890000 hadronic events recorded with the ALEPH detector at LEP. After background subtraction 30.8 ± 6.9 events are attributed to the semileptonic decay of the Bs0 to a Ds- and an opposite-sign lepton. A maximum-likelihood fit to the distribution of the proper times of these events yields a Bs0 lifetime of τBs = 1.92 -0.35+0.45 ± 0.04 ps.

  8. Optimization of fluorescent proteins

    NARCIS (Netherlands)

    Bindels, D.S.; Goedhart, J.; Hink, M.A.; van Weeren, L.; Joosen, L.; Gadella (jr.), T.W.J.; Engelborghs, Y.; Visser, A.J.W.G.

    2014-01-01

    Nowadays, fluorescent protein (FP) variants have been engineered to fluoresce in all different colors; to display photoswitchable, or photochromic, behavior; or to show yet other beneficial properties that enable or enhance a still growing set of new fluorescence spectroscopy and microcopy

  9. Smart optical probes for near-infrared fluorescence imaging of Alzheimer's disease pathology

    International Nuclear Information System (INIS)

    Raymond, Scott B.; Bacskai, Brian J.; Skoch, Jesse; Hills, Ivory D.; Swager, Timothy M.; Nesterov, Evgueni E.

    2008-01-01

    Near-infrared fluorescent probes for amyloid-beta (Aβ) are an exciting option for molecular imaging in Alzheimer's disease research and may translate to clinical diagnostics. However, Aβ-targeted optical probes often suffer from poor specificity and slow clearance from the brain. We are designing smart optical probes that emit characteristic fluorescence signal only when bound to Aβ. We synthesized a family of dyes and tested Aβ-binding sensitivity with fluorescence spectroscopy and tissue-staining. Select compounds exhibited Aβ-dependent changes in fluorescence quantum yield, lifetime, and emission spectra that may be imaged microscopically or in vivo using new lifetime and spectral fluorescence imaging techniques. Smart optical probes that turn on when bound to Aβ will improve amyloid detection and may enable quantitative molecular imaging in vivo. (orig.)

  10. Two-photon excited fluorescence microscopy application for ex vivo investigation of ocular fundus samples

    Science.gov (United States)

    Peters, Sven; Hammer, Martin; Schweitzer, Dietrich

    2011-07-01

    Two-photon excited fluorescence (TPEF) imaging of ocular tissue has recently become a promising tool in ophthalmology for diagnostic and research purposes. The feasibility and the advantages of TPEF imaging, namely deeper tissue penetration and improved high-resolution imaging of microstructures, have been demonstrated lately using human ocular samples. The autofluorescence properties of endogenous fluorophores in ocular fundus tissue are well known from spectrophotometric analysis. But fluorophores, especially when it comes to fluorescence lifetime, typically display a dependence of their fluorescence properties on local environmental parameters. Hence, a more detailed investigation of ocular fundus autofluorescence ideally in vivo is of utmost interest. The aim of this study is to determine space-resolved the stationary and time-resolved fluorescence properties of endogenous fluorophores in ex vivo porcine ocular fundus samples by means of two-photon excited fluorescence spectrum and lifetime imaging microscopy (FSIM/FLIM). By our first results, we characterized the autofluorescence of individual anatomical structures of porcine retina samples excited at 760 nm. The fluorescence properties of almost all investigated retinal layers are relatively homogenous. But as previously unknown, ganglion cell bodies show a significantly shorter fluorescence lifetime compared to the adjacent mueller cells. Since all retinal layers exhibit bi-exponential autofluorescence decays, we were able to achieve a more precise characterization of fluorescence properties of endogenous fluorophores compared to a present in vivo FLIM approach by confocal scanning laser ophthalmoscope (cSLO).

  11. Geant4 simulations of NIST beam neutron lifetime experiment

    Science.gov (United States)

    Valete, Daniel; Crawford, Bret; BL2 Collaboration Collaboration

    2017-09-01

    A free neutron is unstable and its decay is described by the Standard Model as the transformation of a down quark into an up quark through the weak interaction. Precise measurements of the neutron lifetime test the validity of the theory of the weak interaction and provide useful information for the predictions of the theory of Big Bang nucleosynthesis of the primordial helium abundance in the universe and the number of different types of light neutrinos Nν. The predominant experimental methods for determination of the neutron lifetime are commonly called `beam' and `bottle' methods, and the most recent uses of each method do not agree with each other within their stated uncertainties. An improved experiment of the beam technique, which uses magnetic and electric fields to trap and guide the decay protons of a beam of cold neutrons to a detector, is in progress at the National Institute of Standards and Technology, Gaithersburg, MD with a precision goal of 0.1. I acknowledge the support of the Cross-Diciplinary Institute at Gettysburg College.

  12. Fluorescence quantum yield measurements of fluorescent proteins: a laboratory experiment for a biochemistry or molecular biophysics laboratory course.

    Science.gov (United States)

    Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K

    2015-01-01

    Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum. © 2014 The International Union of Biochemistry and Molecular Biology.

  13. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed....... Finally the produce is illustrated on 6 existing UK bridges....

  14. SIRTF thermal design modifications to increase lifetime

    Science.gov (United States)

    Petrick, S. W.

    1993-01-01

    An effort was made to increase the predicted lifetime of the SIRTF dewar by lowering the exterior shell temperature, increasing the radiated energy from the vapor cooled shields and reconfiguring the vapor cooled shields. The lifetime increases can be used to increase the scientific return from the mission and as a trade-off against mass and cost. This paper describes the configurations studied, the steady state thermal model used, the analytical methods and the results of the analysis. Much of the heat input to the outside dewar shell is radiative heat transfer from the solar panel. To lower the shell temperature, radiative cooled shields were placed between the solar panel and the dewar shell and between the bus and the dewar shell. Analysis showed that placing a radiator on the outer vapor cooled shield had a significant effect on lifetime. Lengthening the distance between the outer shell and the point where the vapor cooled shields are attached to the support straps also improved lifetime.

  15. Updated measurement of the $\\tau$ lepton lifetime

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rizzo, G; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Buchmüller, O L; Dhamotharan, S; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Stacey, A M; Williams, M D; Ghete, V M; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Antonelli, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Simion, S; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Lutters, G; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Pütz, J; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G

    1997-01-01

    A new measurement of the mean lifetime of the tau lepton is presented. Three different analysis methods are applied to a sample of 90000 tau pairs, collected in 1993 and 1994 with the ALEPH detector at LEP. The average of this measurement and those previously published by ALEPH is tau_tau = 290.1 +- 1.5 +- 1.1 fs.

  16. Lifetime measurements of the rare earths

    International Nuclear Information System (INIS)

    Stahnke, H.J.

    1981-01-01

    The lifetime of excited energy levels of Praseodymium, Neodymium, Gadolinium, Holmium and Erbium are measured. The measurements were done on atomic beams excited by laser radiation. The experimental results allow an interpretation of the electronic structure of the rare earths. (BEF)

  17. Materials Education: Opportunities over a Lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Schwartz, Lyle H.; Faber, Katherine T.; Cargill III, G. Slade; Houston, Betsy

    2003-10-28

    A report, in the form of abbreviated notes, of the 17th Biennial Conference on National Materials Policy ''Materials Education: Opportunities over a Lifetime'' held May 20-21, 2002 in College Park, MD, sponsored by the Federation of Materials Societies and the University Materials Council.

  18. Smoking expands expected lifetime with musculoskeletal disease

    DEFF Research Database (Denmark)

    Brønnum-Hansen, Henrik; Juel, Knud

    2003-01-01

    By indirect estimation of mortality from smoking and life table methods we estimated expected lifetime without musculoskeletal diseases among never smokers, ex-smokers, and smokers. We found that although life expectancy of a heavy smoker is 7 years shorter than that of a never smoker, heavy...

  19. Disc Golf: Teaching a Lifetime Activity

    Science.gov (United States)

    Eastham, Susan L.

    2015-01-01

    Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…

  20. Lifetime and spin measurements in 40Ar

    International Nuclear Information System (INIS)

    Southon, J.

    1976-01-01

    Lifetimes of levels in 40 Ar populated by the 40 Ar(p,p') reaction have been measured using the Doppler shift attenuation method with a p-γ coincidence technique. A solid argon target was used. The lifetimes determined were (in psec.): 1461 keV level, 1.95 +- 0.15; 2121 keV, >25; 2524 keV, 0.53 +- 0.06; 2893 keV, 4.4 [+2.6,-1.3]; 3208 keV, 0.27. A comprehensive set of branching ratios was also derived and the spins and parities of the 3208 and 4481 keV states were determined to be 2 + and 1 +- respectively. Some of these results suggest that 2 particle -2 hole and 4 particle - 4 hole components are strongly mixed in the low-lying positive parity states in a manner similar to the 2 particle and 4 particle - 2 hole mixing that occurs in 42 Ca. An additional lifetime measurement for the recently discovered high spin state at 3464 keV was carried out using direct electronic timing. The level was excited by the 37 Cl(α,p) reaction and was found to have a lifetime of 1.00 +- 0.03 nsec, which taken together with other evidence indicates that its spin and parity are 6 + . The E2 transition strengths of the 40 Ar 6 + - 4 + - 2 + - 0 + cascade can be simply interpreted in terms of a weak coupling model. (author)

  1. A measurement of the Ds lifetime

    International Nuclear Information System (INIS)

    Braunschweig, W.; Gerhards, R.; Kirschfink, F.J.; Martyn, H.U.; Rosskamp, P.; Kolanoski, A.; Balkwill, C.; Bowler, M.G.; Burrows, P.N.; Cashmore, R.J.; Dauncey, P.; Heath, G.P.; Mellor, D.J.; Ratoff, P.; Tomalin, I.; Yelton, J.M.; Baranko, G.; Caldwell, A.; Cherney, M.; Izen, J.M.; Muller, D.; Ritz, S.; Storm, D.; Takashima, M.; Wicklung, E.; Wu Saulan; Zobernig, G.

    1987-01-01

    The lifetime of the D S meson has been measured using the TASSO detector at PETRA and found to be (5.7 (+3.6-2.6)±0.9) x 10 -13 s. The method used was to reconstruct fully the decay vertex of the channel D s → φπ ± , φ → K + K - . (orig.)

  2. Updated measurement of the τ lepton lifetime

    Science.gov (United States)

    ALEPH Collaboration; Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Becker, U.; Bazarko, A. O.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rizzo, G.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Buchmüller, O.; Dhamotharan, S.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Stacey, A. M.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Sloan, T.; Williams, M. I.; Galla, A.; Giehl, I.; Greene, A. M.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Carr, J.; Coyle, P.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Choi, Y.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Schune, M.-H.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A., III; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-11-01

    A new measurement of the mean lifetime of the τ lepton is presented. Three different analysis methods are applied to a sample of 90 000 τ pairs, collected in 1993 and 1994 with the ALEPH detector at LEP. The average of this measurement and those previously published by ALEPH is ττ=290.1+/-1.5+/-1.1 fs.

  3. Increasing the lifetime of fuel cell catalysts

    NARCIS (Netherlands)

    Latsuzbaia, R.

    2015-01-01

    In this thesis, I discuss a novel idea of fuel cell catalyst regeneration to increase lifetime of the PEM fuel cell electrode/catalyst operation and, therefore, reduce the catalyst costs. As many of the catalyst degradation mechanisms are difficult to avoid, the regeneration is alternative option to

  4. Lifetime oriented maintenance planning in the Netherlands

    NARCIS (Netherlands)

    Straub, A.

    2003-01-01

    In this paper we set up a framework for lifetime oriented maintenance planning as an outcome and input for strategic housing stock management. The maintenance planning holds maintenance activities and costs in the longer term. We consider the maintenance planning as a tool to calculate and implement

  5. Lifetime tests for MAC vertex chamber

    International Nuclear Information System (INIS)

    Nelson, H.N.

    1986-07-01

    A vertex chamber for MAC was proposed to increase precision in the measurement of the B hadron and tau lepton lifetimes. Thin-walled aluminized mylar drift tubes were used for detector elements. A study of radiation hardness was conducted under the conditions of the proposed design using different gases and different operating conditions

  6. Determination of the D mesons lifetimes

    International Nuclear Information System (INIS)

    Josa Mutuberria, M.I.

    1990-01-01

    The results from the experiment NA27, performed in the North Area of the Super Proton Synchrotron at CERN are presented. The experimental set up was the small, high resolution, rapid cyling bubble chamber LEBC coupled with the European Hybrid Spectrometer (EHS). More than 2 millions pictures were taken, with 1015000 in teractions in hydrogen. The stastistical sensitivity of the experiment was 38.5 events/μb. A clean sample of 700 charm particle decays was obtained. Estimators with minimal systematic and statistical errors are developed for the determination of the lifetimes of short-lived particles whose individual momenta are unknown. These estimators make use of the measured decay lengths and the a priori known production characteristics. In this way, it is possible to include identified but not fully reconstructed charm decays in the sample to determine their lifetime. The properties of these estimators were extensively studied by means of Montecarlo simulation. The detection of the short-lived particles through the impact parameter of their charged decay products leads to additional complications which are taken into account. The biases and statistical errors inherent in using simpler approximate lifetime estimators are also discussed. These estimators are applied to determine the lifetime of the D o and D +- mesons using the charm data sample from NA27. (Author)

  7. The Lifetime of a beautiful and charming meson: Bc lifetime measured using the D0 detector

    International Nuclear Information System (INIS)

    Welty-Rieger, Leah Christine

    2008-01-01

    Using approximately 1.3 fb -1 of data collected by the D0 detector between 2002 and 2006, the lifetime of the B c ± meson is studied in the B c ± → J/ψμ ± + X final state. Using an unbinned likelihood simultaneous fit to J/ψ + μ invariant mass and lifetime distributions, a signal of 810 ± 80(stat.) candidates is estimated and a lifetime measurement made of: τ(B c ± ) = 0.448 -0.036 +0.038 (stat) ± 0.032(sys) ps

  8. 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

  9. Steady state and time resolved fluorescence studies of azadioxatriangulenium (ADOTA) fluorophore in silica and PVA thin films

    DEFF Research Database (Denmark)

    Chib, Rahul; Raut, Sangram; Shah, Sunil

    2015-01-01

    A cationic azadioxatriangulenium dye was entrapped in silica thin films obtained by the sol-gel process and in poly (vinyl) alcohol (PVA) thin films. Azadioxatriangulenium is a red emitting fluorophore with a long fluorescence lifetime of ∼20 ns. The fluorescent properties of azadioxatriangulenium...

  10. Scanning fluorescent microscopy is an alternative for quantitative fluorescent cell analysis.

    Science.gov (United States)

    Varga, Viktor Sebestyén; Bocsi, József; Sipos, Ferenc; Csendes, Gábor; Tulassay, Zsolt; Molnár, Béla

    2004-07-01

    Fluorescent measurements on cells are performed today with FCM and laser scanning cytometry. The scientific community dealing with quantitative cell analysis would benefit from the development of a new digital multichannel and virtual microscopy based scanning fluorescent microscopy technology and from its evaluation on routine standardized fluorescent beads and clinical specimens. We applied a commercial motorized fluorescent microscope system. The scanning was done at 20 x (0.5 NA) magnification, on three channels (Rhodamine, FITC, Hoechst). The SFM (scanning fluorescent microscopy) software included the following features: scanning area, exposure time, and channel definition, autofocused scanning, densitometric and morphometric cellular feature determination, gating on scatterplots and frequency histograms, and preparation of galleries of the gated cells. For the calibration and standardization Immuno-Brite beads were used. With application of shading compensation, the CV of fluorescence of the beads decreased from 24.3% to 3.9%. Standard JPEG image compression until 1:150 resulted in no significant change. The change of focus influenced the CV significantly only after +/-5 microm error. SFM is a valuable method for the evaluation of fluorescently labeled cells. Copyright 2004 Wiley-Liss, Inc.

  11. Protein-bound NAD(P)H Lifetime is Sensitive to Multiple Fates of Glucose Carbon.

    Science.gov (United States)

    Sharick, Joe T; Favreau, Peter F; Gillette, Amani A; Sdao, Sophia M; Merrins, Matthew J; Skala, Melissa C

    2018-04-03

    While NAD(P)H fluorescence lifetime imaging (FLIM) can detect changes in flux through the TCA cycle and electron transport chain (ETC), it remains unclear whether NAD(P)H FLIM is sensitive to other potential fates of glucose. Glucose carbon can be diverted from mitochondria by the pentose phosphate pathway (via glucose 6-phosphate dehydrogenase, G6PDH), lactate production (via lactate dehydrogenase, LDH), and rejection of carbon from the TCA cycle (via pyruvate dehydrogenase kinase, PDK), all of which can be upregulated in cancer cells. Here, we demonstrate that multiphoton NAD(P)H FLIM can be used to quantify the relative concentrations of recombinant LDH and malate dehydrogenase (MDH) in solution. In multiple epithelial cell lines, NAD(P)H FLIM was also sensitive to inhibition of LDH and PDK, as well as the directionality of LDH in cells forced to use pyruvate versus lactate as fuel sources. Among the parameters measurable by FLIM, only the lifetime of protein-bound NAD(P)H (τ 2 ) was sensitive to these changes, in contrast to the optical redox ratio, mean NAD(P)H lifetime, free NAD(P)H lifetime, or the relative amount of free and protein-bound NAD(P)H. NAD(P)H τ 2 offers the ability to non-invasively quantify diversions of carbon away from the TCA cycle/ETC, which may support mechanisms of drug resistance.

  12. Theoretical and experimental investigation of atomic radiative lifetimes and hyperfine structures

    International Nuclear Information System (INIS)

    Joensson, Per.

    1992-01-01

    Atomic radiative lifetimes and hyperfine structures as well as other properties, such as total energy and specific mass shift, have been studied theoretically and experimentally. Computer programs to calculate hyperfine structure constants from non-relativistic multiconfiguration Hartree-Fock (MCHF) and relativistic multi-configuration Dirac-Fock (MCDF) wavefunctions have been written. Using these programs large-scale calculations of hyperfine structures in lithium and sodium have been performed. It is shown, that the MCHF method is able to predict hyperfine structures to an accuracy of a few per mille in lithium, whereas for the more complex hyperfine structures to an accuracy of a few per mille in lithium, whereas for the more complex sodium atom an accuracy of a few per cent is obtainable. For lithium convergence of the total energy, ionization energy, specific mass shift and hyperfine parameters has been studied with the MCHF method. Radiative lifetimes and hyperfine structures of excited states in sodium and silver have been experimentally determined using time-resolved laser spectroscopy. By recording the fluorescence light decay curves following VUV excitation, the radiative lifetimes and hyperfine structures of the 7p 2 P states in silver were measured. The delayed-coincidence technique has been used to make very accurate measurements of the radiative lifetimes and hyperfine structures of the lowest P states in sodium and silver

  13. The association of lifetime insight and cognition in psychosis.

    Science.gov (United States)

    Sánchez-Torres, Ana M; Zarzuela, Amalia; Peralta, Victor; Cuesta, Manuel J

    2015-03-01

    Poor insight has been related to poor course in psychosis. However, the role of cognition in insight remains unclear. The aim of this study was to examine the influence of cognition and lifetime psychopathological dimensions on insight in psychosis. We followed up 42 patients with psychotic disorders over 10years. Lifetime psychopathological dimensions and cognitive performance were assessed. Patients were divided into two groups by lifetime patterns of insight and compared with 42 healthy volunteers. Lower IQ and poorer social cognition were associated with higher risks of poorer lifetime insight of feeling ill and global insight respectively. Lifetime negative symptoms were associated with a higher risk of poorer lifetime insight into symptoms. Lifetime lack of insight is independent of cognitive impairment in specific domains, except for social cognition. Higher IQ may contribute to better lifetime awareness of illness, while better ability to manage emotions is involved in lifetime global insight. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Fluorescence decay data analysis correcting for detector pulse pile-up at very high count rates

    Science.gov (United States)

    Patting, Matthias; Reisch, Paja; Sackrow, Marcus; Dowler, Rhys; Koenig, Marcelle; Wahl, Michael

    2018-03-01

    Using time-correlated single photon counting for the purpose of fluorescence lifetime measurements is usually limited in speed due to pile-up. With modern instrumentation, this limitation can be lifted significantly, but some artifacts due to frequent merging of closely spaced detector pulses (detector pulse pile-up) remain an issue to be addressed. We propose a data analysis method correcting for this type of artifact and the resulting systematic errors. It physically models the photon losses due to detector pulse pile-up and incorporates the loss in the decay fit model employed to obtain fluorescence lifetimes and relative amplitudes of the decay components. Comparison of results with and without this correction shows a significant reduction of systematic errors at count rates approaching the excitation rate. This allows quantitatively accurate fluorescence lifetime imaging at very high frame rates.

  15. Interrogation of metabolic and oxygen states of tumors with fiber-based luminescence lifetime spectroscopy.

    Science.gov (United States)

    Lukina, Maria; Orlova, Anna; Shirmanova, Marina; Shirokov, Daniil; Pavlikov, Anton; Neubauer, Antje; Studier, Hauke; Becker, Wolfgang; Zagaynova, Elena; Yoshihara, Toshitada; Tobita, Seiji; Shcheslavskiy, Vladislav

    2017-02-15

    The study of metabolic and oxygen states of cells in a tumor in vivo is crucial for understanding of the mechanisms responsible for tumor development and provides background for the relevant tumor's treatment. Here, we show that a specially designed implantable fiber-optic probe provides a promising tool for optical interrogation of metabolic and oxygen states of a tumor in vivo. In our experiments, the excitation light from a ps diode laser source is delivered to the sample through an exchangeable tip via a multimode fiber, and the emission light is transferred to the detector by another multimode fiber. Fluorescence lifetime of a nicotinamid adenine dinucleotide (NAD(P)H) and phosphorescence lifetime of an oxygen sensor based on an iridium (III) complex of enzothienylpyridine (BTPDM1) are explored both in model experiment in solutions and in living mice.

  16. Lifetime measurements in Crsub(I) by laser excitation from the metastable states

    International Nuclear Information System (INIS)

    Kwiatkowski, M.; Micali, G.; Werner, K.; Zimmermann, P.

    1981-01-01

    A combination of collisional and laser excitation was used to measure radiative lifetimes in Cr I. By a discharge an atomic beam of metastable atoms in the 3d 5 4sa 5 S, a 5 G, b 5 D, a 3 I, b 1 I and 3d 4 4s 2 a 5 D terms was produced. Spatially separated from the place of collisional excitation laser radiation selectively populated levels belonging to the 3d 5 4p z 5 P, y 5 P, u 5 F, u 5 D, x 3 I, y 1 I, 3d 5 5pz 5 G and 3d 4 4s4px 5 G terms. Time-resolved observation of the reemitted resonance fluorescence yielded the lifetimes of 28 levels. The values are compared with other experimental and theoretical results. (orig.)

  17. Results and Systematic Studies of the UCN Lifetime Experiment at NIST

    Science.gov (United States)

    Huffer, Craig Reeves

    The neutron beta-decay lifetime is important in understanding weak interactions in the framework of the Standard Model, and it is an input to nuclear astrophysics and Big Bang Nucleosynthesis. Current measurements of the neutron beta-decay lifetime disagree, which has motivated additional experiments that are sensitive to different sets of systematic effects. An effort continues at the NIST Center for Neutron Research (NCNR) to improve the statistical and systematic limitations of an experiment to measure the neutron beta-decay lifetime using magnetically trapped UCN. In the experiment, a monoenergetic 0:89 nm cold neutron is incident on a superfluid 4He target within the minimum field region of an Ioffe type magnetic trap. Some of the neutrons are subsequently downscattered by single phonons in the helium to low energies (≈ 200 neV), and those in the appropriate spin state become trapped. The inverse process, upscattering of UCN, is suppressed by the low phonon density in the analysis, data, and systematics will be discussed. After accounting for the systematic effects the measured lifetime disagrees with the current PDG mean neutron beta-decay lifetime by about 9 of our standard deviations, which is a strong indication of unaccounted for systematic effects. Additional 3He contamination will be shown to be the most likely candidate for the additional systematic shift, which motivated the commissioning and initial operation of a heat flush purifier for purifying additional 4He. This work ends with a description of the 4He purifier and its performance.

  18. RDM lifetime measurements in 107Cd

    International Nuclear Information System (INIS)

    Andgren, K; Ashley, S F; Regan, P H

    2005-01-01

    Lifetimes for decays linking near-yrast states in 107 Cd have been measured using the recoil distance method (RDM). The nucleus of interest was populated via the 98 Mo( 12 C,3n) 107 Cd fusion-evaporation reaction at an incident beam energy of 60 MeV. From the measured lifetimes, transition probabilities have been deduced and compared with the theoretical B(E2) values for limiting cases of harmonic vibrational and axially deformed rotational systems. Our initial results suggest a rotor-like behaviour for the structure based on the unnatural-parity, h 11/2 orbital in 107 Cd, providing further evidence for the role of this 'shape-polarizing' orbital in stabilizing the nuclear deformation in the A ∼ 100 transitional region

  19. RDM lifetime measurements in 107Cd

    Science.gov (United States)

    Andgren, K.; Ashley, S. F.; Regan, P. H.; McCutchan, E. A.; Zamfir, N. V.; Amon, L.; Cakirli, R. B.; Casten, R. F.; Clark, R. M.; Gürdal, G.; Keyes, K. L.; Meyer, D. A.; Erduran, M. N.; Papenberg, A.; Pietralla, N.; Plettner, C.; Rainovski, G.; Ribas, R. V.; Thomas, N. J.; Vinson, J.; Warner, D. D.; Werner, V.; Williams, E.

    2005-10-01

    Lifetimes for decays linking near-yrast states in 107Cd have been measured using the recoil distance method (RDM). The nucleus of interest was populated via the 98Mo(12C,3n)107Cd fusion-evaporation reaction at an incident beam energy of 60 MeV. From the measured lifetimes, transition probabilities have been deduced and compared with the theoretical B(E2) values for limiting cases of harmonic vibrational and axially deformed rotational systems. Our initial results suggest a rotor-like behaviour for the structure based on the unnatural-parity, h11/2 orbital in 107Cd, providing further evidence for the role of this 'shape-polarizing' orbital in stabilizing the nuclear deformation in the A ~ 100 transitional region.

  20. Experimental lifetimes for Mg-like chlorine

    International Nuclear Information System (INIS)

    Engstroem, L.; Bengtsson, P.; Jupen, C.; Livingston, A.E.; Martinson, I.

    1995-01-01

    The results of beam-foil measurements of lifetimes for low-lying singlet levels in Mg-like chlorine, Cl VI, are presented. The decay curves were analyzed by means of the arbitrarily normalized decay curve method, combined with the recently developed CANYL code, which facilitates studies of decay chains. Cascade corrected data are presented for the levels 3s3p 1 P, 3p 2 1 S, 3p 2 1 D, and 3s3d 1 D, whereas less rigorous lifetime values, based on curve fits, were obtained for the 3p3d 1 D, 3p3d 1 F, and 3s4f 1 F levels. The data are in excellent agreement with recent theoretical values, and previous discrepancies between experiment and theory for short-lived states have been removed

  1. Positron lifetime experiments in indium selenide

    International Nuclear Information System (INIS)

    Cruz, R.M. de la; Pareja, R.

    1988-01-01

    Positron lifetime experiments have been performed on as-grown samples which had been isochronally annealed up to 820 K and plastically deformed and these experiments yield a constant lifetime of 282 ± 2 ps which is attributed to bulk positron states in InSe. Electron-irradiated samples exhibit a two-component spectrum, revealing the presence of positron traps which anneal out at about 330 K. The nature of the native shallow donors in InSe is discussed in the light of the results, which support the idea that native donor centres are probably interstitial In atoms rather than Se vacancies. Positron trapping observed in the electron-irradiated samples is attributed to defects related to In vacancies. (author)

  2. Lifetime modelling of lead acid batteries

    DEFF Research Database (Denmark)

    Bindner, H.; Cronin, T.; Lundsager, P.

    2005-01-01

    The performance and lifetime of energy storage in batteries are an important part of many renewable based energy systems. Not only do batteries impact on the system performance but they are also a significant expenditure when considering the whole lifecycle costs. Poor prediction of lifetime can......, therefore, lead to uncertainty in the viability of the system in the long term. This report details the work undertaken to investigate and develop two different battery life prediction methodologies withspecific reference to their use in hybrid renewable energy systems. Alongside this, results from battery...... tests designed to exercise batteries in similar modes to those that they experience in hybrid systems have also been analysed. These have yieldedbattery specific parameters for use in the prediction software and the first results in the validation process of the software are also given. This work has...

  3. Design, maintenance and lifetime of nuclear components

    International Nuclear Information System (INIS)

    Noel, R.L.; Eisenhut, D.G.; Carey, J.J.; Reynes, L.J.

    1989-01-01

    Division D of SMiRT deals with experience feedback relating to the in-service behavior of nuclear components, the design and construction of this equipment, its maintenance and the evaluation and management of its lifetime. The nuclear industry now having reached maturity, with more than 300 units in service worldwide, these problems are now of predominant importance to the activity of the industry and in its development programs. This applies particularly to the problems relating to the lifetime of nuclear plants, problems which are rightly of such concern both to the utilities, in view of the enormous investments involved, and also to the safety authorities. These contributions have been reviewed for the purpose of analyzing the essential points. This analysis highlights the considerable advances achieved during the recent decades in design and maintenance methods and practices. It also identifies the areas in which progress still remains to be made

  4. A Precise Measurement of the Tau Lifetime

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alderweireld, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, Ugo; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbier, R; Bardin, Dimitri Yuri; Barker, G J; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Berntzon, L; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Bugge, L; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F R; Chapkin, M M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Dalmau, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L S; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Dris, M; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J A; Gandelman, M; García, C; Gavillet, P; Gazis, E N; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Hultqvist, K; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Johansson, P D; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E C; Kernel, G; Kersevan, B P; Kerzel, U; Kiiskinen, A P; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kuznetsov, O; Krumshtein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, R; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V F; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdnyakov, V; Pukhaeva, N; Pullia, A; Rames, J; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Segar, A; Sekulin, R L; Siebel, M; Sissakian, A N; Smadja, G; Smirnova, O G; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Taffard, A C; Tegenfeldt, F; Timmermans, J; Tkatchev, L G; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W A; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O P; Zalewska-Bak, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M

    2004-01-01

    The tau lepton lifetime has been measured with the e+e- -> tau+tau- events collected by the DELPHI detector at LEP in the years 1991-1995. Three different methods have been exploited, using both one-prong and three-prong tau decay channels. Two measurements have been made using events in which both taus decay to a single charged particle. Combining these measurements gave tau_tau (1 prong) = 291.8 +/- 2.3 (stat) +/- 1.5 (sys) fs. A third measurement using taus which decayed to three charged particles yielded tau_tau (3 prong) = 288.6 +/- 2.4 (stat) +/- 1.3 (sys) fs. These were combined with previous DELPHI results to measure the tau lifetime, using the full LEP1 data sample, to be tau_tau = 290.9 +/- 1.4 (stat) +/- 1.0 (sys) fs.

  5. A precise measurement of the tau lifetime

    International Nuclear Information System (INIS)

    Abdallah, J.; Abreu, P.; Adam, W.

    2004-01-01

    The tau lepton lifetime has been measured with the e + e - →τ + τ - events collected by the DELPHI detector at LEP in the years 1991-1995. Three different methods have been exploited, using both one-prong and three-prong τ decay channels. Two measurements have been made using events in which both taus decay to a single charged particle. Combining these measurements gave τ τ (1 prong) = 291.8±2.3 stat ±1.5 sys fs. A third measurement using taus which decayed to three charged particles yielded τ τ (3 prong) = 288.6±.4 stat ±1.3 sys fs. These were combined with previous DELPHI results to measure the tau lifetime, using the full LEP1 data sample, to be τ τ = 290.9±1.4 stat ±1.0 sys fs. (orig.)

  6. Time resolved fluorescence of cow and goat milk powder

    Science.gov (United States)

    Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

    2017-01-01

    Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

  7. A luminescence lifetime assisted ratiometric fluorimeter for biological applications

    Science.gov (United States)

    Lam, Hung; Kostov, Yordan; Rao, Govind; Tolosa, Leah

    2009-12-01

    In general, the most difficult task in developing devices for fluorescence ratiometric sensing is the isolation of signals from overlapping emission wavelengths. Wavelength discrimination can be achieved by using monochromators or bandpass filters, which often lead to decreased signal intensities. The result is a device that is both complex and expensive. Here we present an alternative system—a low-cost standalone optical fluorimeter based on luminescence lifetime assisted ratiometric sensing (LARS). This paper describes the principle of this technique and the overall design of the sensor device. The most significant innovation of LARS is the ability to discriminate between two overlapping luminescence signals based on differences in their luminescence decay rates. Thus, minimal filtering is required and the two signals can be isolated despite significant overlap of luminescence spectra. The result is a device that is both simple and inexpensive. The electronic circuit employs the lock-in amplification technique for the signal processing and the system is controlled by an onboard microcontroller. In addition, the system is designed to communicate with external devices via Bluetooth.

  8. Lifetime monogamy and the evolution of eusociality

    DEFF Research Database (Denmark)

    Boomsma, Jacobus J

    2009-01-01

    and termites is thus analogous to the evolution of multicellularity. Focusing on lifetime monogamy as a universal precondition for the evolution of obligate eusociality simplifies the theory and may help to resolve controversies about levels of selection and targets of adaptation. The monogamy window...... underlines that cooperative breeding and eusociality are different domains of social evolution, characterized by different sectors of parameter space for Hamilton's rule....

  9. A measurement of the Omega /sup -/ lifetime

    CERN Document Server

    Bourquin, M; Chatelus, Y; Chollet, J C; Degré, A; Froidevaux, D; Fyfe, A R; Gaillard, J M; Gee, C N P; Gibson, W M; Igo-Kemenes, P; Jeffreys, P W; Merkel, B; Morand, R; Plothow, H; Repellin, J P; Saunders, B J; Sauvage, G; Schiby, B; Siebert, H W; Smith, V J; Streit, K P; Strub, R; Tovey, Stuart N; Tresher, J J

    1979-01-01

    In an experiment at the CERN-SPS charged-hyperon beam, a sample of 2500 Omega /sup -/ to Lambda K/sup -/ decays has been collected at Omega /sup -/ momenta at 98.5 and 115 GeV/c. The Omega /sup -/ lifetime is found to be tau /sub Omega /=(0.822+or-0.028)*10/sup -10/ s. (15 refs).

  10. A bimodal flexible distribution for lifetime data

    OpenAIRE

    Ramires, Thiago G.; Ortega, Edwin M. M.; Cordeiro, Gauss M.; Hens, Niel

    2016-01-01

    A four-parameter extended bimodal lifetime model called the exponentiated log-sinh Cauchy distribution is proposed. It extends the log-sinh Cauchy and folded Cauchy distributions. We derive some of its mathematical properties including explicit expressions for the ordinary moments and generating and quantile functions. The method of maximum likelihood is used to estimate the model parameters. We implement the fit of the model in the GAMLSS package and provide the codes. The flexibility of the...

  11. Fatigue lifetime estimation of railway axles

    Czech Academy of Sciences Publication Activity Database

    Náhlík, Luboš; Pokorný, Pavel; Ševčík, Martin; Fajkoš, R.; Matušek, P.; Hutař, Pavel

    2017-01-01

    Roč. 73, MAR (2017), s. 139-157 ISSN 1350-6307 R&D Projects: GA MŠk LM2015069; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Residual fatigue lifetime * Railway axle * Variable amplitude loading * Fatigue crack propagation * Damage tolerance methodology Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis Impact factor: 1.676, year: 2016

  12. Life-Times of Simulated Traffic Jams

    OpenAIRE

    Nagel, K.

    1993-01-01

    We study a model for freeway traffic which includes strong noise taking into account the fluctuations of individual driving behavior. The model shows emergent traffic jams with a self-similar appearance near the throughput maximum of the traffic. The lifetime distribution of these jams shows a short scaling regime, which gets considerably longer if one reduces the fluctuations for driving at maximum speed but leaves the fluctuations for slowing down or accelerating unchanged. The outflow from...

  13. Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

    Energy Technology Data Exchange (ETDEWEB)

    Skytt, P.; Glans, P.; Gunnelin, K. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons could not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.

  14. Lifetime and performance of NSLS storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Halama, H.J.

    1988-01-01

    The performance of synchrotron light sources is measured primarily in terms of beam lifetime, beam size, and the recovery of normal operation after a section of the machine has been brought to atmospheric pressure. The beam lifetime and the beam size depend on the following phenomena: Beam gas interaction which can be either elastic or inelastic scattering on residual gas nuclei or electrons. With the exception of low energy machines, this phenomenon represents the main limiting factor on lifetime; Beam interaction with trapped ions causing both beam loss and defocussing. Residual gas molecules are ionized both by circulating beam and synchrotron radiation. The cross sections for both processes are comparable. The effects of this phenomenon are most troublesome at low energies. The problem can be eliminated by switching to positron beams. Installing clearing electrodes has also been successful; Intrabeam scattering (Touschek effect) is caused by Coulomb scattering among electrons of the same bunch as they execute betatron oscillations. The Touschek effect is strongly dependent on energy and in general is a problem only in low energy machines; and Various instabilities causing both slow and fast beam decay which have been observed in both NSLS rings. A special case due to dust particles that fall into the electron beam is commonly observed in early stages of conditioning. Coherent collective instabilities will not be discussed in this paper. 19 refs., 4 figs., 1 tab.

  15. Lifetime and performance of NSLS storage rings

    International Nuclear Information System (INIS)

    Halama, H.J.

    1988-01-01

    The performance of synchrotron light sources is measured primarily in terms of beam lifetime, beam size, and the recovery of normal operation after a section of the machine has been brought to atmospheric pressure. The beam lifetime and the beam size depend on the following phenomena: Beam gas interaction which can be either elastic or inelastic scattering on residual gas nuclei or electrons. With the exception of low energy machines, this phenomenon represents the main limiting factor on lifetime; Beam interaction with trapped ions causing both beam loss and defocussing. Residual gas molecules are ionized both by circulating beam and synchrotron radiation. The cross sections for both processes are comparable. The effects of this phenomenon are most troublesome at low energies. The problem can be eliminated by switching to positron beams. Installing clearing electrodes has also been successful; Intrabeam scattering (Touschek effect) is caused by Coulomb scattering among electrons of the same bunch as they execute betatron oscillations. The Touschek effect is strongly dependent on energy and in general is a problem only in low energy machines; and Various instabilities causing both slow and fast beam decay which have been observed in both NSLS rings. A special case due to dust particles that fall into the electron beam is commonly observed in early stages of conditioning. Coherent collective instabilities will not be discussed in this paper. 19 refs., 4 figs., 1 tab

  16. The programs for lifetime extension by AREVA

    International Nuclear Information System (INIS)

    Knoche, P.

    2014-01-01

    In 2011 AREVA launched 2 worldwide programs to meet the demands of its customers: 'AREVA Safety Alliance' that proposes a set of measures for post-Fukushima safety upgrading and 'AREVA Forward Alliance' that is dedicated to lifetime extension projects. Concerning 'AREVA Safety Alliance' about 150 projects have been carried out for 53 customers in 19 countries, as for 'AREVA Forward Alliance' 60% of the lifetime extension projects in the US have been performed by AREVA. In the framework of lifetime extension projects, upgrading measures and services are proposed such as the installation of hydrogen recombiner units, of filtered ventilation systems for severe accidents, or the upgrading of the reactor control system through the implementation of the digital Teleperm XS technology, or recommendations about the methodology to follow for the repair or replacement of important components. The replacement of steam generators and of the pressurizer and with other upgrading works led to a gain of 18.5% on the output power of the Ringhals-4 unit. (A.C.)

  17. Strength and lifetime of polymer glasses

    Energy Technology Data Exchange (ETDEWEB)

    Bartenev, G.M.; Kartasov, E.M.

    1981-03-01

    A kinetic equation of the time-dependence of strength (complete isotherm of lifetime) of polymer glasses at stress values ranging from the limiting stress of the occurence of separation breaks to the critical stress is derived. The curvature of lifetime plots occuring at low and high periods of time in the experiments are considered. The ranges of noncritical state, breaks caused by a thermofluctuation mechanism, a transition range and athermal breaks are discerned. The limitations of applicability of the basic empirical equation of the kinetic theory of the time-dependence of strength are explained. Theoretical equations are suggested for calculating various characteristics of the brittle break, as limiting stress and critical stress, relative critical craze length and coefficient of stress concentration at the craze tip with respect to various geometrical configurations of the craze and its position in the sample. With polymethylmethacrylate as an example in the brittle and quasi-brittle state, as characterized by the transition from the rupture of sets of chemical bonds to individual chemical bonds, the thermofluctuation processes of break in polymer glasses are discussed. The application of the thermofluctuation theory of solids to the quasi-brittle fracture is considered. The growth kinetics of crazes and the corresponding equation of lifetime were found to be described by identical (corresponding) analytical expressions by which the changes of the coefficients of stress concentration in the range of microplastic deformation in front of the growing is covered within a wide region of temperature including the brittle temperature.

  18. MODIS on-orbit thermal emissive bands lifetime performance

    Science.gov (United States)

    Madhavan, Sriharsha; Wu, Aisheng; Chen, Na; Xiong, Xiaoxiong

    2016-05-01

    MODerate resolution Imaging Spectroradiometer (MODIS), a leading heritage sensor in the fleet of Earth Observing System for the National Aeronautics and Space Administration (NASA) is in space orbit on two spacecrafts. They are the Terra (T) and Aqua (A) platforms. Both instruments have successfully continued to operate beyond the 6 year design life time, with the T-MODIS currently functional beyond 15 years and the A-MODIS operating beyond 13 years respectively. The MODIS sensor characteristics include a spectral coverage from 0.41 μm - 14.4 μm, of which wavelengths ranging from 3.7 μm - 14. 4 μm cover the thermal infrared region also referred to as the Thermal Emissive Bands (TEBs). The TEBs is calibrated using a v-grooved BlackBody (BB) whose temperature measurements are traceable to the National Institute of Standards and Technology temperature scales. The TEBs calibration based on the onboard BB is extremely important for its high radiometric fidelity. In this paper, we provide a complete characterization of the lifetime instrument performance of both MODIS instruments in terms of the sensor gain, the Noise Equivalent difference Temperature, key instrument telemetry such as the BB lifetime trends, the instrument temperature trends, the Cold Focal Plane telemetry and finally, the total assessed calibration uncertainty of the TEBs.

  19. GaN-based superluminescent diodes with long lifetime

    Science.gov (United States)

    Castiglia, A.; Rossetti, M.; Matuschek, N.; Rezzonico, R.; Duelk, M.; Vélez, C.; Carlin, J.-F.; Grandjean, N.

    2016-02-01

    We report on the reliability of GaN-based super-luminescent light emitting diodes (SLEDs) emitting at a wavelength of 405 nm. We show that the Mg doping level in the p-type layers has an impact on both the device electro-optical characteristics and their reliability. Optimized doping levels allow decreasing the operating voltage on single-mode devices from more than 6 V to less than 5 V for an injection current of 100 mA. Furthermore, maximum output powers as high as 350 mW (for an injection current of 500 mA) have been achieved in continuous-wave operation (CW) at room temperature. Modules with standard and optimized p-type layers were finally tested in terms of lifetime, at a constant output power of 10 mW, in CW operation and at a case temperature of 25 °C. The modules with non-optimized p-type doping showed a fast and remarkable increase in the drive current during the first hundreds of hours together with an increase of the device series resistance. No degradation of the electrical characteristics was observed over 2000 h on devices with optimized p-type layers. The estimated lifetime for those devices was longer than 5000 h.

  20. Proton detection in the neutron lifetime experiment PENeLOPE

    Energy Technology Data Exchange (ETDEWEB)

    Tietze, Christian [Technische Universitaet Muenchen, Physik Department E18 (Germany); Collaboration: PENeLOPE-Collaboration

    2015-07-01

    Although neutron lifetime plays an important role in the Standard Model of particle physics, τ{sub n} is not very precisely know and often discussed. The official PDG mean value has been lowered during the last years by more than 6σ to the new value of 880.3 ± 1.1 s. The new precision experiment PENeLOPE, which is currently developed at Technische Universitaet Muenchen, will help to clear this up. Ultra-cold neutrons are lossless stored in a magneto-gravitational trap, formed by superconducting coils. The combined determination of τ{sub n} by counting the surviving neutrons after each storage cycle on one side and in-situ detection of the decay protons on the other side together with a very good handle on systematic errors leads to an unprecedented precision of the neutron lifetime value of 0.1s. This contribution will give an overview of the challenges concerning proton detection under the exceptional requirements of this experiment. The developed concept of using avalanche photodiodes for direct proton detection will be presented as well as results from first measurements with a prototype detector read out by particular developed electronics.

  1. A search for GMSB sleptons with lifetime at ALEPH

    International Nuclear Information System (INIS)

    Jones, Luke Timothy

    2002-01-01

    A search for slepton production via the decay of pair-produced neutralinos has been performed under the assumption that the sleptons have observable lifetime in the detector before each decaying to a lepton and a gravitino. Sleptons, neutralinos and gravitinos are particles predicted by the theory of supersymmetry, and are the supersymmetric partners of the Standard Model leptons, neutral bosons and of the graviton respectively. The search was performed in 628 pb -1 of data taken by the ALEPH detector at LEP centre-of-mass energies from 189 to 208 GeV. It was motivated by general predictions of Gauge-Mediated Supersymmetry Breaking (GMSB) models in which the lightest supersymmetric particle is always the gravitino. No evidence of the process was found. Model-independent cross-section limits are quoted as a function of neutralino mass, slepton mass and slepton lifetime in the case that the neutralino branching ratios to each slepton are equal at 1/3 (the so-called slepton co-NLSP scenario) and in the case that the neutralino decays exclusively to the stau (the stau-NLSP scenario). Excluded regions in the neutralino-stau mass plane are shown for four gravitino masses under model-specific assumptions. (author)

  2. A search for GMSB sleptons with lifetime at ALEPH

    CERN Document Server

    Jones, Luke Timothy

    2001-01-01

    A search for slepton production via the decay of pair-produced neutralinos has been performed under the assumption that the sleptons have observable lifetime in the detector before each decaying to a lepton and a gravitino. Sleptons, neutralinos and gravitinos are particles predicted by the theory of supersymmetry, and are the supersymmetric partners of the Standard Model leptons, neutral bosons and of the graviton respectively. The search was performed in 628 inverse picobarns of data taken by the ALEPH detector at LEP centre-of-mass energies from 189 to 208 GeV. It was motivated by general predictions of Gauge-Mediated Supersymmetry Breaking (GMSB) models in which the lightest supersymmetric particle is always the gravitino. No evidence of the process was found. Model-independent cross-section limits are quoted as a function of neutralino mass, slepton mass and slepton lifetime in the case that the neutralino branching ratios to each slepton are equal at one third (the so-called slepton co-NLSP scenario) an...

  3. Atomic-fluorescence spectrophotometry

    International Nuclear Information System (INIS)

    Bakhturova, N.F.; Yudelevich, I.G.

    1975-01-01

    Atomic-fluorescence spectrophotometry, a comparatively new method for the analysis of trace quantities, has developed rapidly in the past ten years. Theoretical and experimental studies by many workers have shown that atomic-fluorescence spectrophotometry (AFS) is capable of achieving a better limit than atomic absorption for a large number of elements. The present review examines briefly the principles of atomic-fluorescence spectrophotometry and the types of fluorescent transition. The excitation sources, flame and nonflame atomizers, used in AFS are described. The limits of detection achieved up to the present, using flame and nonflame methods of atomization are given

  4. Fluorescence of irradiated hydrocarbons

    International Nuclear Information System (INIS)

    Gulis, I.G.; Evdokimenko, V.M.; Lapkovskij, M.P.; Petrov, P.T.; Gulis, I.M.; Markevich, S.V.

    1977-01-01

    A visible fluorescence has been found out in γ-irradiated aqueous of carbohydrates. Two bands have been distinguished in fluorescence spectra of the irradiated solution of dextran: a short-wave band lambdasub(max)=140 nm (where lambda is a wave length) at lambdasub(β)=380 nm and a long-wave band with lambdasub(max)=540 nm at lambdasub(β)=430 nm. A similar form of the spectrum has been obtained for irradiated solutions of starch, amylopectin, lowmolecular glucose. It has been concluded that a macromolecule of polysaccharides includes fluorescent centres. A relation between fluorescence and α-oxiketon groups formed under irradiation has been pointed out

  5. Experimental assessment of fluorescence microscopy signal enhancement by stimulated emission

    Science.gov (United States)

    Dake, Fumihiro; Yazawa, Hiroki

    2017-10-01

    The quantity of photons generated during fluorescence microscopy is principally determined by the quantum yield of the fluorescence dyes and the optical power of the excitation beam. However, even though low quantum yields can produce poor images, it is challenging to tune this parameter, while increasing the power of the excitation beam often results in photodamage. Here, we propose the use of stimulated emission (SE) as a means of enhancing both the signal intensity and signal-to-noise ratio during confocal fluorescence microscopy. This work experimentally confirmed that both these factors can be enhanced by SE radiation, through generating a greater number of photons than are associated with the standard fluorescence signal. We also propose the concept of stimulated emission enhancing fluorescence (SEEF) microscopy, which employs both the SE and fluorescence signals, and demonstrate that the intensity of an SEEF signal is greater than those of the individual SE and fluorescence signals.

  6. Collisional and radiative processes in fluorescent lamps

    International Nuclear Information System (INIS)

    Lister, Graeme G.

    2003-01-01

    Since electrode life is the major limiting factor in operating fluorescent lamps, many lighting companies have introduced 'electrodeless' fluorescent lamps, using inductively coupled discharges. These lamps often operate at much higher power loadings than standard lamps and numerical models have not been successful in reproducing experimental measurements in the parameter ranges of interest. A comprehensive research program was undertaken to study the fundamental physical processes of these discharges, co-funded by the Electric Power Research Institute (EPRI) and OSRAM SYLVANIA under the name of ALITE. The program included experiments and modeling of radiation transport, computations of electron-atom and atom-atom cross sections and the first comprehensive power balance studies of a highly loaded fluorescent lamp. Results from the program and their importance to the understanding of the physics of fluorescent lamps are discussed, with particular emphasis on the important collisional and radiative processes. Comparisons between results of experimental measurements and numerical models are presented

  7. Using the fluorescence of DBO to study the aggregation of asphaltenes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zixin; Bohne, Cornelia [Department of Chemistry, University of Victoria (Canada)], email: xyang@uvic.ca

    2010-07-01

    Asphaltene, operationally defined as the fraction of bitumen that is insoluble in heptane but soluble in toluene, is the least characterized component of crude oil. It can aggregate at low concentrations, causing problems in the reservoir and during transport and processing. Fluorescence techniques have been employed to characterize asphaltenes, e.g. by adding external probes. DBO (2,3-diazabicyclo [2.2.2]oct-2-ene), a fluorescence probe molecule with a long fluorescence lifetime, was made sensitive to the presence of aliphatic C-H bonds. DBO was used as an external fluorescent probe to characterize the aggregation of Athabasca asphaltene. The lifetime of DBO was measured using single photon counting. Preliminary lifetime measurements show that AA-5 quenches the emission of DBO, leading to a shortening of the DBO lifetime. The abrupt decrease in lifetime may be related to the interaction of DBO with the AA-5 aggregate; further studies are being performed to test this hypothesis. In conclusion, DBO interacts with asphaltene components and has the potential for being used as a probe to study the asphaltene aggregation.

  8. Octanol reduces end-plate channel lifetime

    Science.gov (United States)

    Gage, Peter W.; McBurney, Robert N.; Van Helden, Dirk

    1978-01-01

    1. Post-synaptic effects of n-octanol at concentrations of 0·1-1 mM were examined in toad sartorius muscles by use of extracellular and voltage-clamp techniques. 2. Octanol depressed the amplitude and duration of miniature end-plate currents and hence depressed neuromuscular transmission. 3. The decay of miniature end-plate currents remained exponential in octanol solutions even when the time constant of decay (τD) was decreased by 80-90%. 4. The lifetime of end-plate channels, obtained by analysis of acetylcholine noise, was also decreased by octanol. The average lifetime measured from noise spectra agreed reasonably well with the time constant of decay of miniature end-plate currents, both in control solution and in octanol solutions. 5. Octanol caused a reduction in the conductance of end-plate channels. Single channel conductance was on average about 25 pS in control solution and 20 pS in octanol. 6. In most cells the normal voltage sensitivity of the decay of miniature end-plate currents was retained in octanol solutions. The lifetime of end-plate channels measured from acetylcholine noise also remained voltage-sensitive in octanol solutions. In some experiments in which channel lifetime was exceptionally reduced the voltage sensitivity was less than normal. 7. In octanol solutions, τD was still very sensitive to temperature changes in most cells although in some the temperature sensitivity of τD was clearly reduced. Changes in τD with temperature could generally be fitted by the Arrhenius equation suggesting that a single step reaction controlled the decay of currents both in control and in octanol solutions. In some cells in which τD became less than 0·3 ms, the relationship between τD and temperature became inconsistent with the Arrhenius equation. 8. As the decay of end-plate currents in octanol solutions remains exponential, and the voltage and temperature sensitivity can be unchanged even when τD is significantly reduced, it seems likely that

  9. Use of astronomy filters in fluorescence microscopy.

    Science.gov (United States)

    Piper, Jörg

    2012-02-01

    Monochrome astronomy filters are well suited for use as excitation or suppression filters in fluorescence microscopy. Because of their particular optical design, such filters can be combined with standard halogen light sources for excitation in many fluorescent probes. In this "low energy excitation," photobleaching (fading) or other irritations of native specimens are avoided. Photomicrographs can be taken from living motile fluorescent specimens also with a flash so that fluorescence images can be created free from indistinctness caused by movement. Special filter cubes or dichroic mirrors are not needed for our method. By use of suitable astronomy filters, fluorescence microscopy can be carried out with standard laboratory microscopes equipped with condensers for bright-field (BF) and dark-field (DF) illumination in transmitted light. In BF excitation, the background brightness can be modulated in tiny steps up to dark or black. Moreover, standard industry microscopes fitted with a vertical illuminator for examinations of opaque probes in DF or BF illumination based on incident light (wafer inspections, for instance) can also be used for excitation in epi-illumination when adequate astronomy filters are inserted as excitatory and suppression filters in the illuminating and imaging light path. In all variants, transmission bands can be modulated by transmission shift.

  10. TR-LIF LIFETIME MEASUREMENTS AND HFR+CPOL CALCULATIONS OF RADIATIVE PARAMETERS IN VANADIUM ATOM (V I)

    International Nuclear Information System (INIS)

    Wang, Q.; Jiang, L. Y.; Shang, X.; Tian, Y. S.; Dai, Z. W.; Quinet, P.; Palmeri, P.; Zhang, W.

    2014-01-01

    Radiative lifetimes of 79 levels belonging to the 3d 3 4s4p, 3d 4 4p, 3d 3 4s5p, 3d 4 5p, and 3d 3 4s4d configurations of V I with energy from 26,604.807 to 46,862.786 cm –1 have been measured using time-resolved laser-induced fluorescence (TR-LIF) spectroscopy in laser-produced plasma. The lifetime values reported in this paper are in the range of 3.3-494 ns, and the uncertainties of these measurements are within ±10%. A good agreement was obtained with previous data. HFR+CPOL calculations have been performed and used to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical transition probabilities for 784 V I transitions

  11. Excited-state lifetime measurement of silicon vacancy centers in diamond by single-photon frequency upconversion

    Science.gov (United States)

    Rong, Youying; Ma, Jianhui; Chen, Lingxiao; Liu, Yan; Siyushev, Petr; Wu, Botao; Pan, Haifeng; Jelezko, Fedor; Wu, E.; Zeng, Heping

    2018-05-01

    We report a method with high time resolution to measure the excited-state lifetime of silicon vacancy centers in bulk diamond avoiding timing jitter from the single-photon detectors. Frequency upconversion of the fluorescence emitted from silicon vacancy centers was achieved from 738 nm to 436 nm via sum frequency generation with a short pump pulse. The excited-state lifetime can be obtained by measuring the intensity of upconverted light while the pump delay changes. As a probe, a pump laser with pulse duration of 11 ps provided a high temporal resolution of the measurement. The lifetime extracted from the pump–probe curve was 0.755 ns, which was comparable to the timing jitter of the single-photon detectors.

  12. Theoretical calculations of positron lifetimes for metal oxides

    International Nuclear Information System (INIS)

    Mizuno, Masataka; Araki, Hideki; Shirai, Yasuharu

    2004-01-01

    Our recent positron lifetime measurements for metal oxides suggest that positron lifetimes of bulk state in metal oxides are shorter than previously reported values. We have performed theoretical calculations of positron lifetimes for bulk and vacancy states in MgO and ZnO using first-principles electronic structure calculations and discuss the validity of positron lifetime calculations for insulators. By comparing the calculated positron lifetimes to the experimental values, it wa found that the semiconductor model well reproduces the experimental positron lifetime. The longer positron lifetime previously reported can be considered to arise from not only the bulk but also from the vacancy induced by impurities. In the case of cation vacancy, the calculated positron lifetime based on semiconductor model is shorter than the experimental value, which suggests that the inward relaxation occurs around the cation vacancy trapping the positron. (author)

  13. Determination of absolute Ba densities during dimming operation of fluorescent lamps by laser-induced fluorescence measurements

    International Nuclear Information System (INIS)

    Hadrath, S; Beck, M; Garner, R C; Lieder, G; Ehlbeck, J

    2007-01-01

    Investigations of fluorescent lamps (FL) are often focused on the electrodes, since the lifetime of the lamps is typically limited by the electrode lifetime and durability. During steady state operation, the work function lowering emitter material, in particular, barium, is lost. Greater barium losses occur under dimming conditions, in which reduced discharge currents lead to increased cathode falls, the result of the otherwise diminished heating of the electrode by the bombarding plasma ions. In this work the barium density near the electrodes of (FL), operating in high frequency dimming mode is investigated using the high-sensitivity method of laser-induced fluorescence. From these measurements we infer barium loss for a range of discharge currents and auxiliary coil heating currents. We show that the Ba loss can very easily be reduced by moderate auxiliary coil heating

  14. LED-induced fluorescence diagnostics for turbine and combustion engine thermometry

    International Nuclear Information System (INIS)

    Allison, S.W.

    2001-01-01

    Fluorescence from phosphor coatings is the basis of an established technique for measuring temperature in a wide variety of turbine and combustion engine applications. Example surfaces include blades, vanes, combustors, intake valves, pistons, and rotors. Many situations that are remote and noncontact require the high intensity of a laser to illuminate the phosphor, especially if the surface is moving. Thermometric resolutions of 0.1 C are obtainable, and some laboratory versions of these systems have been calibrated against NIST standards to even higher precision. To improve the measurement signal-to-noise ratio, synchronous detection timing has been used to repeatedly interrogate the same blade in a high speed rotating turbine. High spatial resolution can be obtained by tightly focusing the interrogation beam in measurements of static surfaces, and by precise differential timing of the laser pulses on rotating surfaces. We report here the use of blue light emitting diodes (LEDs) as a n illumination source for producing useable fluorescence from phosphors for temperature measurements. An LED can excite most of the same phosphors used to cover the temperature range from 8 to 1400 C. The advantages of using LEDs are obvious in terms of size, power requirements, space requirements and cost. There can also be advantages associated with very long operating lifetimes, wide range of available colors, and their broader emission bandwidths as compared to laser diodes. Temperature may be inferred either from phase or time-decay determinations

  15. A sensitive fluorescence quenching method for the detection of tartrazine with acriflavine in soft drinks.

    Science.gov (United States)

    Yang, Huan; Ran, Guihua; Yan, Jingjing; Zhang, Hui; Hu, Xiaoli

    2018-03-01

    In this work, a simple, rapid, sensitive, selective spectrofluorimetric method was applied to detect tartrazine. The fluorescence of acriflavine could be efficiently quenched by tartrazine. The method manifested real time response as well as presented satisfied linear relationship to tartrazine. The linear response range of tartrazine (R 2 = 0.9995) was from 0.056 to 5 μmol L -1 . The detection limit (3σ/k) was 0.017 μmol L -1 , indicating that this method could be applied to detect traces of tartrazine. The accuracy and precision of the method was further assured by recovery studies via a standard addition method, with percentage recoveries in the range of 96.0% to 103.0%. Moreover, a quenching mechanism was investigated systematically by the linear plots at varying temperatures based on the Stern-Volmer equation, fluorescence lifetime and UV-visible absorption spectra, all of which proved to be static quenching. This sensitive, selective assay possessed a great application prospect for the food industry owing to its simplicity and rapidity for the detection of tartrazine. Copyright © 2017 John Wiley & Sons, Ltd.

  16. Optimizing design of converters using power cycling lifetime models

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Ørndrup; Munk-Nielsen, Stig

    2015-01-01

    Converter power cycling lifetime depends heavily on converter operation point. A lifetime model of a single power module switched mode power supply with wide input voltage range is shown. A lifetime model is created using a power loss model, a thermal model and a model for power cycling capability...... with a given mission profile. A method to improve the expected lifetime of the converter is presented, taking into account switching frequency, input voltage and transformer turns ratio....

  17. Lifetime measurements in N=Z 72Kr

    Science.gov (United States)

    Andreoiu, C.; Svensson, C. E.; Austin, R. A. E.; Carpenter, M. P.; Dashdorj, D.; Finlay, P.; Freeman, S. J.; Garrett, P. E.; Görgen, A.; Greene, J.; Grinyer, G. F.; Hyland, B.; Jenkins, D.; Johnston-Theasby, F.; Joshi, P.; Machiavelli, A. O.; Moore, F.; Mukherjee, G.; Phillips, A. A.; Reviol, W.; Sarantites, D. G.; Schumaker, M. A.; Seweryniak, D.; Smith, M. B.; Valiente-Dobón, J. J.; Wadsworth, R.

    2006-07-01

    High-spin states in the N=Z nucleus 72Kr have been populated in the 40Ca(40Ca, 2α)72Kr fusion-evaporation reaction at a beam energy of 165 MeV and using a thin isotopically enriched 40Ca target. The experiment, performed at Argonne National Laboratory close to Chicago, USA, employed the Gammasphere array for γ-ray detection coupled to the Microball array for charged particle detection. The previously observed bands in 72Kr were extended to a higher excitation energy of ~24 MeV and higher angular momentum of 30planck. Using the Doppler-shift attenuation method, the lifetimes of high-spin states were measured for the first time in order to investigate deformation changes associated with the g9/2 proton and neutron alignments in this N=Z nucleus. An excellent agreement with theoretical calculations including only standard t=1 np pairing was observed.

  18. Field-induced negative differential spin lifetime in silicon.

    Science.gov (United States)

    Li, Jing; Qing, Lan; Dery, Hanan; Appelbaum, Ian

    2012-04-13

    We show that the electric-field-induced thermal asymmetry between the electron and lattice systems in pure silicon substantially impacts the identity of the dominant spin relaxation mechanism. Comparison of empirical results from long-distance spin transport devices with detailed Monte Carlo simulations confirms a strong spin depolarization beyond what is expected from the standard Elliott-Yafet theory even at low temperatures. The enhanced spin-flip mechanism is attributed to phonon emission processes during which electrons are scattered between conduction band valleys that reside on different crystal axes. This leads to anomalous behavior, where (beyond a critical field) reduction of the transit time between spin-injector and spin-detector is accompanied by a counterintuitive reduction in spin polarization and an apparent negative spin lifetime.

  19. A New Theoretical Approach to Single-Molecule Fluorescence Optical Studies of RNA Dynamics

    International Nuclear Information System (INIS)

    Zhao Xinghai; Shan Guangcun; Bao Shuying

    2011-01-01

    Single-molecule fluorescence spectroscopy in condensed phases has many important chemical and biological applications. The single-molecule fluorescence measurements contain information about conformational dynamics on a vast range of time scales. Based on the data analysis protocols methodology proposed by X. Sunney Xie, the theoretical study here mainly focuses on the single-molecule studies of single RNA with interconversions among different conformational states, to with a single FRET pair attached. We obtain analytical expressions for fluorescence lifetime correlation functions that relate changes in fluorescence lifetime to the distance-dependent FRET mechanism within the context of the Smoluchowski diffusion model. The present work establishes useful guideline for the single-molecule studies of biomolecules to reveal the complicated folding dynamics of single RNA molecules at nanometer scale.

  20. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    Fluorescence spectroscopy-based techniques using conventional fluorimeters have been extensively applied since the late 1960s to study different aspects of membrane-related phenomena, i.e., mainly relating to lipid-lipid and lipid-protein (peptide) interactions. Even though fluorescence...

  1. Radiation lifetimes and failure mechanisms of carbon stripper foils

    International Nuclear Information System (INIS)

    Auble, R.L.

    1981-01-01

    Measurements of lifetimes of thin carbon foils under heavy-ion irradiation are compiled and recent advances in stripper foil technology are reviewed. The impact of recent foil lifetime improvements, many by more than an order of magnitude, on heavy-ion electrostatic accelerators is discussed. Foil inhomogeneities, particularly those caused by sputtering are suggested to be a prime factor in usable foil lifetimes

  2. Measurement of the effective $B_s^0 \\to K^+ K^-$ lifetime

    CERN Document Server

    Aaij, R; Adametz, A; Adeva, B; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves Jr, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Beddow, J; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M -O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Cauet, Ch; Charles, M; Charpentier, Ph; Chen, P; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Corti, G; Couturier, B; Cowan, G A; Craik, D; Currie, R; D'Ambrosio, C; David, P; David, P N Y; De Bonis, I; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Del Buono, L; Deplano, C; Derkach, D; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Domingo Bonal, F; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Elsby, D; Esperante Pereira, D; Falabella, A; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gascon, D; Gaspar, C; Gauld, R; Gauvin, N; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Harrison, P F; Hartmann, T; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hoballah, M; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kaballo, M; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kenyon, I R; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Kochebina, O; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kudryavtsev, V; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J -P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li, Y; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; von Loeben, J; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Lu, H; Luisier, J; Mac Raighne, A; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Massafferri, A; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McCarthy, J; McGregor, G; McNulty, R; Meissner, M; Merk, M; Merkel, J; Milanes, D A; Minard, M -N; Molina Rodriguez, J; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Muster, B; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neufeld, N; Nguyen, A D; Nguyen-Mau, C; Nicol, M; Niess, V; Nikitin, N; Nikodem, T; Nomerotski, A; Novoselov, A; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B K; Palacios, J; Palano, A; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C; Pazos Alvarez, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perego, D L; Perez Trigo, E; Pérez-Calero Yzquierdo, A; Perret, P; Perrin-Terrin, M; Pessina, G; Petrolini, A; Phan, A; Picatoste Olloqui, E; Pie Valls, B; Pietrzyk, B; Pilař, T; Pinci, D; Plackett, R; Playfer, S; Plo Casasus, M; Polci, F; Polok, G; Poluektov, A; Polycarpo, E; Popov, D; Popovici, B; Potterat, C; Powell, A; Prisciandaro, J; Pugatch, V; Puig Navarro, A; Qian, W; Rademacker, J H; Rakotomiaramanana, B; Rangel, M S; Raniuk, I; Raven, G; Redford, S; Reid, M M; dos Reis, A C; Ricciardi, S; Richards, A; Rinnert, K; Roa Romero, D A; Robbe, P; Rodrigues, E; Rodrigues, F; Rodriguez Perez, P; Rogers, G J; Roiser, S; Romanovsky, V; Rosello, M; Rouvinet, J; Ruf, T; Ruiz, H; Sabatino, G; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salzmann, C; Sanmartin Sedes, B; Sannino, M; Santacesaria, R; Santamarina Rios, C; Santinelli, R; Santovetti, E; Sapunov, M; Sarti, A; Satriano, C; Satta, A; Savrie, M; Savrina, D; Schaack, P; Schiller, M; Schindler, H; Schleich, S; Schlupp, M; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M -H; Schwemmer, R; Sciascia, B; Sciubba, A; Seco, M; Semennikov, A; Senderowska, K; Sepp, I; Serra, N; Serrano, J; Seyfert, P; Shapkin, M; Shapoval, I; Shatalov, P; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, O; Shevchenko, V; Shires, A; Silva Coutinho, R; Skwarnicki, T; Smith, N A; Smith, E; Smith, M; Sobczak, K; Soler, F J P; Solomin, A; Soomro, F; Souza, D; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Stagni, F; Stahl, S; Steinkamp, O; Stoica, S; Stone, S; Storaci, B; Straticiuc, M; Straumann, U; Subbiah, V K; Swientek, S; Szczekowski, M; Szczypka, P; Szumlak, T; T'Jampens, S; Teklishyn, M; Teodorescu, E; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Tolk, S; Topp-Joergensen, S; Torr, N; Tournefier, E; Tourneur, S; Tran, M T; Tsaregorodtsev, A; Tuning, N; Ubeda Garcia, M; Ukleja, A; Uwer, U; Vagnoni, V; Valenti, G; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; Velthuis, J J; Veltri, M; Vesterinen, M; Viaud, B; Videau, I; Vieira, D; Vilasis-Cardona, X; Visniakov, J; Vollhardt, A; Volyanskyy, D; Voong, D; Vorobyev, A; Vorobyev, V; Voß, C; Voss, H; Waldi, R; Wallace, R; Wandernoth, S; Wang, J; Ward, D R; Watson, N K; Webber, A D; Websdale, D; Whitehead, M; Wicht, J; Wiedner, D; Wiggers, L; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wishahi, J; Witek, M; Witzeling, W; Wotton, S A; Wright, S; Wu, S; Wyllie, K; Xie, Y; Xing, F; Xing, Z; Yang, Z; Young, R; Yuan, X; Yushchenko, O; Zangoli, M; Zavertyaev, M; Zhang, F; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhong, L; Zvyagin, A

    2012-01-01

    A precise determination of the effective $B_s^0 \\rightarrow K^+ K^-$ lifetime can be used to constrain contributions from physics beyond the Standard Model in the $B_s^0$ meson system. Conventional approaches select $B$ meson decay products that are significantly displaced from the $B$ meson production vertex. As a consequence, $B$ mesons with low decay times are suppressed, introducing a bias to the decay time spectrum which must be corrected. This analysis uses a technique that explicitly avoids a lifetime bias by using a neural network based trigger and event selection. Using 1.0~fb$^{-1}$ of data recorded by the LHCb experiment, the effective $B_s^0 \\rightarrow K^+ K^-$ lifetime is measured as $1.455 \\pm 0.046 \\; \\mathrm{(stat.)} \\pm 0.006 \\; \\mathrm{(syst.)} \\, \\mathrm{ps}.$

  3. Lifetime Fluorescence and Raman Imaging for Detection of Wound Failure and Heterotopic Ossification

    Science.gov (United States)

    2015-12-01

    December 2015 TYPE OF REPORT: Final PREPARED FOR: U.S. Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012...valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE December 2015 2. REPORT TYPE Final 3. DATES COVERED...failure facilitates increased risk of infection and can lead to permanent disabilities or death. Current treatment methods include regular debridement

  4. Alfa hemolisina induce un aumento de calcio eritrocitario: estudio por FLIM (Fluorescence Lifetime Imaging Microscopy)

    OpenAIRE

    Sánchez, Susana; Bakás, Laura; Gratton, Enrico; Herlax, Vanesa Silvana

    2010-01-01

    Alfa hemolisina (HlyA), miembro representativo de la familia de toxinas RTX (Repeat in toxin), es una toxina proteica que ciertas cepas patógenas de E.coli secretan específicamente al medio. Está demostrado que la toxina es un factor importante de virulencia en enfermedades extraintestinales. Además, se ha determinado que el desarrollo de falla renal aguda aumenta significativamente la mortalidad en pacientes con shock séptico producido por bacterias Gram negativas, en los que distintos facto...

  5. In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique

    NARCIS (Netherlands)

    Mik, Egbert G.; Johannes, Tanja; Zuurbier, Coert J.; Heinen, Andre; Houben-Weerts, Judith H. P. M.; Balestra, Gianmarco M.; Stap, Jan; Beek, Johan F.; Ince, Can

    2008-01-01

    Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we

  6. Molecular rheometry: direct determination of viscosity in Lo and Ld lipid phases via fluorescence lifetime imaging

    Czech Academy of Sciences Publication Activity Database

    Wu, Y.; Štefl, Martin; Olžyńska, Agnieszka; Hof, Martin; Yahioglu, G.; Yip, P.; Casey, D. R.; Ces, O.; Humpolíčková, Jana; Kuimova, M. K.

    2013-01-01

    Roč. 15, č. 36 (2013), s. 14986-14993 ISSN 1463-9076 R&D Projects: GA ČR GBP208/12/G016; GA MŠk LH13259 Institutional support: RVO:61388955 Keywords : CORRELATION SPECTROSCOPY * MODEL MEMBRANES * LIVE CELLS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.198, year: 2013

  7. Ato protein interactions in yeast plasma membrane revealed by fluorescence lifetime imaging (FLIM)

    Czech Academy of Sciences Publication Activity Database

    Strachotová, Dita; Holoubek, A.; Kučerová, Helena; Benda, Aleš; Humpolíčková, Jana; Váchová, Libuše; Palková, Z.

    2012-01-01

    Roč. 1818, č. 9 (2012), s. 2126-2134 ISSN 0005-2736 R&D Projects: GA ČR GA204/08/0718; GA MŠk(CZ) LC06063; GA MŠk(CZ) LC531 Institutional research plan: CEZ:AV0Z40400503 Institutional support: RVO:61388971 Keywords : Ammonium exporters Ato1p * Ato2p and Ato3p * FLIM-photobleaching technique Subject RIV: CE - Biochemistry Impact factor: 3.389, year: 2012

  8. Real-time histology in liver disease using multiphoton microscopy with fluorescence lifetime imaging

    OpenAIRE

    Wang, Haolu; Liang, Xiaowen; Mohammed, Yousuf H.; Thomas, James A.; Bridle, Kim R.; Thorling, Camilla A.; Grice, Jeffrey E.; Xu, Zhi Ping; Liu, Xin; Crawford, Darrell H. G.; Roberts, Michael S.

    2015-01-01

    Conventional histology with light microscopy is essential in the diagnosis of most liver diseases. Recently, a concept of real-time histology with optical biopsy has been advocated. In this study, live mice livers (normal, with fibrosis, steatosis, hepatocellular carcinoma and ischemia-reperfusion injury) were imaged by MPM-FLIM for stain-free real-time histology. The acquired MPM-FLIM images were compared with conventional histological images. MPM-FLIM imaged subsurface cellular and subcellu...

  9. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

    Czech Academy of Sciences Publication Activity Database

    Burdikova, Z.; Svindrych, Z.; Pala, J.; Hickey, C. D.; Wilkinson, M. G.; Pánek, Jiří; Auty, M. A. E.; Periasamy, A.; Sheehan, J. J.

    2015-01-01

    Roč. 6, March (2015), 183_1-183_10 ISSN 1664-302X Institutional support: RVO:61389013 Keywords : cheese matrix * C-SNARF-4 * Oregon Green Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.165, year: 2015

  10. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

    OpenAIRE

    Zuzana eBurdikova; Zdenek eSvindrych; Jan ePala; Cian eHickey; Martin G. Wilkinson; Jiri ePanek; Mark A. E. Auty; Ammasi ePeriasamy; Jeremiah J. Sheehan

    2015-01-01

    Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a signi...

  11. Plant lifetime management and research program

    International Nuclear Information System (INIS)

    Sakai, K.; Nagayama, M.

    1993-01-01

    The importance of nuclear power generation has been increasing in Japan. Because the lower generation cost and more stable fuel supply, in comparison with the case of fossil plants, are beneficial to Japan which has scarce natural resources. In addition, nuclear power generation is expected to help reduce carbon dioxide emission which causes global warming. In these circumstances, the safe and stable operations of nuclear power plants are of prime importance, and the frequency of unscheduled shutdown has been kept low in Japan as a result of thorough periodic inspections supported by aging management. This paper covers the development process of the aging management program and related research programs in The Kansai Electric Power Co., Inc. (KEPCO). KEPCO runs 11 nuclear power units (PWR). A Table shows the commencement date of commercial operation and operating hours for each unit. The early plants, such as Mihama-2 Unit, have been operated for more than 100,000 hours and are in the phase of aging management. Accordingly, we have been conducting aging management programs since 1987. in order to identify age-related degradation and work out countermeasures.The aging management programs have ensured safe and stable operation of nuclear power plants. Each result of the lifetime assessment has provided the information which helps establishing maintenance programs. For example, the result of the lifetime assessment has been reflected to the intervals of overhaulings and inspections, and the replacement timing of some components. In the future activities of aging management should be revised and should focus lifetime assessment on components which provoke difficulties in inspections because of high radiation exposure or high inspection cost

  12. Lifetime earnings for physicians across specialties.

    Science.gov (United States)

    Leigh, J Paul; Tancredi, Daniel; Jerant, Anthony; Romano, Patrick S; Kravitz, Richard L

    2012-12-01

    Earlier studies estimated annual income differences across specialties, but lifetime income may be more relevant given physicians' long-term commitments to specialties. Annual income and work hours data were collected from 6381 physicians in the nationally representative 2004-2005 Community Tracking Study. Data regarding years of residency were collected from AMA FREIDA. Present value models were constructed assuming 3% discount rates. Estimates were adjusted for demographic and market covariates. Sensitivity analyses included 4 alternative models involving work hours, retirement, exogenous variables, and 1% discount rate. Estimates were generated for 4 broad specialty categories (Primary Care, Surgery, Internal Medicine and Pediatric Subspecialties, and Other), and for 41 specific specialties. The estimates of lifetime earnings for the broad categories of Surgery, Internal Medicine and Pediatric Subspecialties, and Other specialties were $1,587,722, $1,099,655, and $761,402 more than for Primary Care. For the 41 specific specialties, the top 3 (with family medicine as reference) were neurological surgery ($2,880,601), medical oncology ($2,772,665), and radiation oncology ($2,659,657). The estimates from models with varying rates of retirement and including only exogenous variables were similar to those in the preferred model. The 1% discount model generated estimates that were roughly 150% larger than the 3% model. There was considerable variation in the lifetime earnings across physician specialties. After accounting for varying residency years and discounting future earnings, primary care specialties earned roughly $1-3 million less than other specialties. Earnings' differences across specialties may undermine health reform efforts to control costs and ensure adequate numbers of primary care physicians.

  13. [The intraoperative determination of intestinal vitality with a fluorescent indicator].

    Science.gov (United States)

    Ivanov, A; Terziev, I

    1997-01-01

    Intestinal obstruction due to strangulation is induced in dogs under experimental conditions, with intestinal wall vitality assessment done on the ground of standard clinical criteria, using fluorescence dye and UV rays, as well as histological study. Sensitivity, specificity and prognostic value of each of the methods employed are determined. The fluorescence method advantages are recorded, and the prospects of its clinical implementation are estimated.

  14. An image fiber based fluorescent probe with associated signal processing scheme for biomedical diagnostics

    International Nuclear Information System (INIS)

    Vaishakh, M; Murukeshan, V M; Seah, L K

    2008-01-01

    A dual-modality image fiber based fluorescent probe that can be used for depth sensitive imaging and suppression of fluorescent emissions with nanosecond lifetime difference is proposed and illustrated in this paper. The system can give high optical sectioning and employs an algorithm for obtaining phase sensitive images. The system can find main application in in vivo biomedical diagnostics for detecting biochemical changes for distinguishing malignant tissue from healthy tissue

  15. RDM lifetime measurement in 167Lu

    International Nuclear Information System (INIS)

    Rohilla, Aman; Gupta, C.K.; Chamoli, S.K.; Singh, R.P.; Muralithar, S.; Ashok Kumar; Govil, I.M.

    2014-01-01

    In this paper we are presenting the experiment performed for measuring lifetime in 167 Lu, which provides the measurement of the structural behavior of the nuclei due to single particle excitation. The enhanced γ-ray detection GDA setup present at IUAC was used and the data was acquired in the singles mode with the condition when any two of the BGO's element fire in coincidence with a Ge detector. The online data acquisition program CANDLE was used for data acquire in conjunction with CAMAC based data acquisition hardware

  16. RDM lifetimes measurements in 179Re

    International Nuclear Information System (INIS)

    Chamoli, S.; Joshi, P.; Kumar, A.; Govil, I.M.; Singh, R.P.; Chatturvedi, L.

    2001-01-01

    The study of Re nuclei in the mass region from 170-190 is of particular interest as they lie in a region where the Nilsson orbitals exhibit large driving effects on the nuclear shape, presenting the strong possibility of shape coexistence. To see the variation of the deformation driving property of different bands and the other related phenomena like delay in band crossing frequency for intruder configuration h 92 in these nuclei with increasing in neutron number the lifetime measurement in 179 Re nucleus is done

  17. Comparison of methods for calculating decay lifetimes

    International Nuclear Information System (INIS)

    Tobocman, W.

    1978-01-01

    A simple scattering model is used to test alternative methods for calculating decay lifetimes, or equivalently, resonance widths. We consider the scattering of s-wave particles by a square well with a square barrier. Exact values for resonance energies and resonance widths are compared with values calculated from Wigner-Weisskopf perturbation theory and from the Garside-MacDonald projection operator formalism. The Garside-MacDonald formalism gives essentially exact results while the predictions of the Wigner-Weisskopf formalism are fairly poor

  18. Lifetime evaluation of Bohunice NPP components

    International Nuclear Information System (INIS)

    Kupca, L.

    2001-01-01

    The paper discuss some aspects of the main primary components lifetime evaluation program in Bohunice NPP which is performed by Nuclear Power Plant Research Institute (NPPRI) Trnava in cooperation with Bohunice and other organizations involved. Facts presented here are based on the NPPRI research report which is regularly issued after each reactor fuel campaign under conditions of project resulted from the contract between NPPRI and Bohunice NPP. For the calculations, there has been used some computer codes adapted (or made) by NPPRI and the results are just the conclusive and very brief, presented here in Tables (Figures). (authors)

  19. The fluorescence intensities ratio is not a reliable parameter for evaluation of protein unfolding transitions.

    Science.gov (United States)

    Žoldák, Gabriel; Jancura, Daniel; Sedlák, Erik

    2017-06-01

    Monitoring the fluorescence of proteins, particularly the fluorescence of intrinsic tryptophan residues, is a popular method often used in the analysis of unfolding transitions (induced by temperature, chemical denaturant, and pH) in proteins. The tryptophan fluorescence provides several suitable parameters, such as steady-state fluorescence intensity, apparent quantum yield, mean fluorescence lifetime, position of emission maximum that are often utilized for the observation of the conformational/unfolding transitions of proteins. In addition, the fluorescence intensities ratio at different wavelengths (usually at 330 nm and 350 nm) is becoming an increasingly popular parameter for the evaluation of thermal transitions. We show that, under certain conditions, the use of this parameter for the analysis of unfolding transitions leads to the incorrect determination of thermodynamic parameters characterizing unfolding transitions in proteins (e.g., melting temperature) and, hence, can compromise the hit identification during high-throughput drug screening campaigns. © 2017 The Protein Society.

  20. Fluorescence correction in electron probe microanalysis

    International Nuclear Information System (INIS)

    Castellano, Gustavo; Riveros, J.A.

    1987-01-01

    In this work, several expressions for characteristic fluorescence corrections are computed, for a compilation of experimental determinations on standard samples. Since this correction does not take significant values, the performance of the different models is nearly the same; this fact suggests the use of the simplest available expression. (Author) [es