Science.gov

Sample records for air fluorescence light

  1. Fluorescence light microscopy of pulmonary surfactant at the air-water interface of an air bubble of adjustable size.

    PubMed

    Knebel, D; Sieber, M; Reichelt, R; Galla, H-J; Amrein, M

    2002-07-01

    The structural dynamics of pulmonary surfactant was studied by epifluorescence light microscopy at the air-water interface of a bubble as a model close to nature for an alveolus. Small unilamellar vesicles of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylglycerol, a small amount of a fluorescent dipalmitoylphosphatidylcholine-analog, and surfactant-associated protein C were injected into the buffer solution. They aggregated to large clusters in the presence of Ca(2+) and adsorbed from these units to the interface. This gave rise to an interfacial film that eventually became fully condensed with dark, polygonal domains in a fluorescent matrix. When now the bubble size was increased or decreased, respectively, the film expanded or contracted. Upon expansion of the bubble, the dark areas became larger to the debit of the bright matrix and reversed upon contraction. We were able to observe single domains during the whole process. The film remained condensed, even when the interface was increased to twice its original size. From comparison with scanning force microscopy directly at the air-water interface, the fluorescent areas proved to be lipid bilayers associated with the (dark) monolayer. In the lung, such multilayer phase acts as a reservoir that guarantees a full molecular coverage of the alveolar interface during the breathing cycle and provides mechanical stability to the film. PMID:12080141

  2. Fluorescence and Light Scattering

    ERIC Educational Resources Information Center

    Clarke, Ronald J.; Oprysa, Anna

    2004-01-01

    The aim of the mentioned experiment is to aid students in developing tactics for distinguishing between signals originating from fluorescence and light scattering. Also, the experiment provides students with a deeper understanding of the physicochemical bases of each phenomenon and shows that the techniques are actually related.

  3. Scattered Light And Fluorescent Photomechanics

    NASA Astrophysics Data System (ADS)

    Fourney, M. E.; Chang, Ban W.

    1987-02-01

    A new technique for determining the stress state in a three-dimensional transparent body is described. This method involves cast-ing dye molecules into a model material and using the fluorescent light to analysis the stress state. The techniques of scattered light photoelasticity and speckle interferometry are considered and the enhancement of these techniques by the use of fluorescent is reported. The amount of illumination is greatly increased and the wavelength red-shifted, which eliminates the undesirable boundary halo; however, at the expense of a loss of coherence and a degree of depolarization of the light. Rhodamine 6G dye molecules are cast into gelatin, epoxy resin (PLM-4) and urethane rubber (Solithane 113) model materials. The light scattering, fluorescent, and fringe formation processes of each material is investigated. It is observed that even for the standard scattered light photoelastic materials without dye molecules the scattering is not Rayleigh, but rather has a large amount of wavelength broadening, the center wavelength, is red-shifted, and a high degree of depolarization occurs. A theory of photoelastic fringe formation for fluorescent materials is proposed. Experimental results are presented and the use of digital image processor in filtering background illumination is shown to greatly enhance fringe visibility.

  4. Shedding Some Light on Fluorescent Bulbs.

    ERIC Educational Resources Information Center

    Guilbert, Nicholas R.

    1996-01-01

    Explores some of the principles behind the working of fluorescent bulbs using a specially prepared fluorescent bulb with the white inner fluorescent coating applied along only half its length. Discusses the spectrum, the bulb plasma, and light production. (JRH)

  5. High intensity portable fluorescent light

    NASA Technical Reports Server (NTRS)

    Kendall, F. B.

    1972-01-01

    Eight high intensity portable fluorescent lights were produced. Three prototype lights were also produced, two of which were subsequently updated to the physical and operational configuration of the qualification and flight units. Positioning of lamp apertures and reflectors in these lights is such that the light is concentrated and intensified in a specific pattern rather than widely diffused. Indium amalgam control of mercury vapor pressure in the lamp gives high output at lamp ambient temperatures up to 105 C. A small amount of amalgam applied to each electrode stem helps to obtain fast warm-up. Shrinking a Teflon sleeve on the tube and potting metal caps on each end of the lamp minimizes dispersion of mercury vapor and glass particles in the event of accidental lamp breakage. Operation at 20 kHz allows the lamps to consume more power than at low frequency, thus increasing their light output and raising their efficiency. When used to expose color photographic film, light from the lamps produces results approximately equal to sunlight.

  6. Light Sheet Fluorescence Microscopy (LSFM)

    PubMed Central

    Adams, Michael W.; Loftus, Andrew F.; Dunn, Sarah E.; Joens, Matthew S.; Fitzpatrick, James A.J.

    2015-01-01

    The development of confocal microscopy techniques introduced the ability to optically section fluorescent samples in the axial dimension, perpendicular to the image plane. These approaches, via the placement of a pinhole in the conjugate image plane, provided superior resolution in the axial (z) dimension resulting in nearly isotropic optical sections. However, increased axial resolution, via pinhole optics, comes at the cost of both speed and excitation efficiency. Light Sheet Fluorescent Microscopy (LSFM), a century old idea (Siedentopf and Zsigmondy, 1902) made possible with modern developments in both excitation and detection optics, provides sub-cellular resolution and optical sectioning capabilities without compromising speed or excitation efficiency. Over the past decade, several variations of LSFM have been implemented each with its own benefits and deficiencies. Here we discuss LSFM fundamentals and outline the basic principles of several major light sheet based imaging modalities (SPIM, inverted SPIM, multi-view SPIM, Bessel beam SPIM, and stimulated emission depletion SPIM while considering their biological relevance in terms of intrusiveness, temporal resolution, and sample requirements. PMID:25559221

  7. Modeling fluorescent light distributions in scattering media

    NASA Astrophysics Data System (ADS)

    Phillips, Kevin G.; Jacques, Steven L.

    2010-02-01

    It is hoped that the non-invasive optical characterization of physiological features of normal and diseased epithelia can be assessed through the fluorescent emission of such tissues. With a high percentage of cancers arising in the epithelium, the characterization of carcinogenesis in such tissues is imperative. Fluorescent emission from the epithelium, e.g. oral mucosa, has been shown to be sensitive to physiological features, such as cellular morphology, and the amount and types of biochemical agents present in the tissue. Efforts to distinguish the spectral signatures of diseased and healthy states of tissues from fluorescence have been confounded by the distortion of the intrinsic fluorescent signature as a result of wavelength dependent absorption and scattering within the tissue. Theoretical models of light propagation in biological media are required for understanding the distortion of the intrinsic fluorescence arising from compromised tissues. In this work we model the distortion of the intrinsic fluorescence emitted from a tissue with wavelength dependent optical properties, arising from varying blood and water content, using the radiative transport equation. As an example, we demonstrate the ability of blood and water content to distort the signal of a white light source as it is embedded deeper into a tissue.

  8. Fluorescence enhancement in visible light: dielectric or noble metal?

    PubMed

    Sun, S; Wu, L; Bai, P; Png, C E

    2016-07-28

    A high permittivity dielectric gives the impression of outperforming plasmonic noble metal in visible light fluorescence enhancement primarily because of its small loss. Nonetheless, the performances of these two platforms in various situations remain obscure due to the different optical confinement mechanisms as well as the complexity in the fluorescence enhancement process. This study presents a comprehensive comparison between these two platforms based on nanoparticles (NPs) to evaluate their capability and applicability in fluorescence enhancement by taking into account the fluorescence excitation rate, the quantum yield, the fluorophore wavelengths and Stokes shifts as well as the far field intensity. In a low permittivity sensing medium (e.g. air), the dielectric NP can achieve comparable or higher fluorescence enhancement than the metal NP due to its decent NP-enhanced excitation rate and larger quantum yield. In a relatively high permittivity sensing medium (e.g. water), however, there is a significant decrement of the excitation rate of the dielectric NP as the permittivity contrast decreases, leading to a smaller fluorescence enhancement compared to the metallic counterpart. Combining the fluorescence enhancement and the far field intensity studies, we further conclude that for both dielectric and plasmonic NPs, the optimal situation occurs when the fluorescence excitation wavelength, the fluorescence emission wavelength and the electric-dipole-mode of the dielectric NP (or the plasmonic resonance of the metal NP) are the same and all fall in the low conductivity region of the NP material. We also find that the electric-dipole-mode of the dielectric NP performs better than the magnetic-dipole-mode for fluorescence enhancement applications because only the electric-dipole-mode can be strongly excited by the routinely used fluorescent dyes and quantum dots, which behave as electric dipoles by nature. PMID:27374052

  9. An optical microsensor to measure fluorescent light intensity in biofilms.

    PubMed

    Beyenal, Haluk; Yakymyshyn, Chris; Hyungnak, Jeon; Davis, Catherine C; Lewandowski, Zbigniew

    2004-09-01

    We have developed an optical microsensor to quantify fluorescent light intensity distribution in biofilms. The optical system consisted of a beam splitter, light couplers, filters and a spectrophotometer able to accept the fiberoptic cable to measure fluorescent light intensity. The emitted light, fluorescence from the biofilm, was collected at the tip of the optical microsensor and was transferred to a spectrophotometer via a fiberoptic cable. The total fluorescent light intensity was evaluated from the emission spectrum by numerical integration. The newly developed fiberoptic microsensor was tested using a Staphylococcus aureus strain producing yellow fluorescent protein (YFP) grown as biofilm. We used a 405-nm violet laser diode for excitation, and measured the emission intensity between 480 nm and 540 nm. The optical microsensor that quantifies fluorescent light intensity is a promising tool in biofilm research which often requires detection and quantification of fluorescent light intensity distribution generated by various fluorescent proteins. PMID:15279941

  10. High Hats, Swiss Cheese, and Fluorescent Lighting?

    SciTech Connect

    McCullough, Jeffrey J.; Gordon, Kelly L.

    2002-08-30

    For DOE, PNNL is conducting a competitive procurement to promote market introduction of new residential recessed downlights (also known as ''recessed cans'' or ''high hats'') that are airtight, rated for insulated ceilings, and hard-wired for CFLs. This paper discusses the potential energy savings of new high-efficiency downlights, and the results of product testing to date. Recessed downlights are the most popular residential lighting fixtures in the United States, with 21.7 million fixtures sold in 2000. An estimated 350 million are currently installed in American homes. Recessed cans are relatively inexpensive, and provide an unobtrusive, directed source of light for kitchens, hallways, and living rooms. Recessed cans are energy-intensive in three ways. First, virtually all recessed cans currently installed in the residential sector use incandescent light sources, typically reflector-type lamps drawing 65-150 watts. Second, heat from incandescent lamps adds to air-conditioning loads. Third, most installed recessed cans are not airtight, so they allow conditioned air to escape from the living area into unconditioned spaces such as attics. Addressing both lighting energy use and air leakage in recessed cans has proven challenging. Lighting energy efficiency is greatly improved by using CFLs. Air leakage can be addressed by making fixtures airtight. But when CFLs are used in an airtight recessed can, heat generated by the lamp and ballast is trapped within the fixture. Excessive heat causes reduced light output and shorter lifespan of the CFL. The procurement was designed to overcome these technical challenges and make new products available in the marketplace.

  11. NEXT GENERATION ENERGY EFFICIENT FLUORESCENT LIGHTING PRODUCT

    SciTech Connect

    Alok Srivastava; Anant Setlur

    2003-04-01

    This is the Final Report of the Next-Generation Energy Efficient Fluorescent Lighting Products program, Department of Energy (DOE). The overall goal of this three-year program was to develop novel phosphors to improve the color rendition and efficiency of compact and linear fluorescent lamps. The prime technical approach was the development of quantum-splitting phosphor (QSP) to further increase the efficiency of conventional linear fluorescent lamps and the development of new high color rendering phosphor blends for compact fluorescent lamps (CFLs) as potential replacements for the energy-hungry and short-lived incandescent lamps in market segments that demand high color rendering light sources. We determined early in the project that the previously developed oxide QSP, SrAl{sub 12}O{sub 19}:Pr{sup 3+}, did not exhibit an quantum efficiency higher than unity under excitation by 185 nm radiation, and we therefore worked to determine the physical reasons for this observation. From our investigations we concluded that the achievement of quantum efficiency exceeding unity in SrAl{sub 12}O{sub 19}:Pr{sup 3+} was not possible due to interaction of the Pr{sup 3+} 5d level with the conduction band of the solid. The interaction which gives rise to an additional nonradiative decay path for the excitation energy is responsible for the low quantum efficiency of the phosphor. Our work has led to the development of a novel spectroscopic method for determining photoionzation threshold of luminescent centers in solids. This has resulted in further quantification of the requirements for host phosphor lattice materials to optimize quantum efficiency. Because of the low quantum efficiency of the QSP, we were unable to demonstrate a linear fluorescent lamp with overall performance exceeding that of existing mercury-based fluorescent lamps. Our work on the high color rendering CFLs has been very successful. We have demonstrated CFLs that satisfies the EnergyStar requirement with color

  12. Sustainable LED Fluorescent Light Replacement Technology

    SciTech Connect

    2011-06-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: • Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life. • Environmental Impact Review – Designs are

  13. Fluorescent lighting with aluminum nitride phosphors

    DOEpatents

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  14. Light-induced fluorescence for pulpal diagnosis

    NASA Astrophysics Data System (ADS)

    Ebihara, Arata; Liaw, Lih-Huei L.; Krasieva, Tatiana B.; Wilder-Smith, Petra B. B.

    2001-04-01

    A direct non-histological means of pulpal diagnosis remains elusive to clinical practice. Clinical vitality testing remains limited to electric, thermal criteria, or laser Doppler flowmetry. The goal of these investigations was to determine the feasibility of using light-induced fluorescence as a non-invasive modality for pulpal evaluation. Such a capability would, for example, permit expanded use of pulpotomy/pulpectomy techniques. Clinically healthy and diseased human extirpated pulpal tissues were used in this study. After excision, they were rapidly frozen and standard cryosections prepared. Measurement of tissue excitation/emission characteristics was performed using spectrographic analysis. A low-light level fluorescence microscopy system was then used to image autofluorescence localization and intensity at optimal excitation/detection parameters. Excitation/detection parameters used in this study included 405/605, 405/635, 405/670, 440/550, and 440/635. Autofluorescence intensities in healthy tissues were significantly stronger than those in diseased tissues at optimal parameters. It is postulated that autofluorescence characteristics are related to pathology- related structural changes in the pulp. This work provides the basis for further investigation into the relation between autofluorescence, histology and clinical symptoms.

  15. Fluorescent light bulbs - energy saver or environmental hazard?

    SciTech Connect

    Christenson, S.M.

    1995-03-01

    Businesses and homeowners have installed millions of fluorescent light bulbs in buildings around the country in the last few decades. Because fluorescent light bulbs are energy efficient and save electricity, environmentalists and governmental officials - including U.S. EPA - have promoted their use. Yet, fluorescent bulbs raise environmental concerns of their own. When these bulbs burn out, environmental and facility managers face complex issues about whether the old bulbs are regulated as hazardous waste.

  16. Fluorescent Photochromic Diarylethene That Turns on with Visible Light.

    PubMed

    Sumi, Takaki; Kaburagi, Tomohiro; Morimoto, Masakazu; Une, Kanako; Sotome, Hikaru; Ito, Syoji; Miyasaka, Hiroshi; Irie, Masahiro

    2015-10-01

    A new fluorescent photochromic diarylethene that can be activated by irradiation with 405 nm light was synthesized. The turn-on mode switching of fluorescence with visible light is favorable for application to biological systems. The fluorescence quantum yield of the photogenerated closed-ring isomer was as high as 0.8 in less or medium polar solvents, and even in polar acetonitrile the yield was higher than 0.6. PMID:26376422

  17. Multimodal light-sheet microscopy for fluorescence live imaging

    NASA Astrophysics Data System (ADS)

    Oshima, Y.; Kajiura-Kobayashi, H.; Nonaka, S.

    2012-03-01

    Light-sheet microscopy, it is known as single plane illumination microscope (SPIM), is a fluorescence imaging technique which can avoid phototoxic effects to living cells and gives high contrast and high spatial resolution by optical sectioning with light-sheet illumination in developmental biology. We have been developed a multifunctional light-sheet fluorescence microscopy system with a near infrared femto-second fiber laser, a high sensitive image sensor and a high throughput spectrometer. We performed that multiphoton fluorescence images of a transgenic fish and a mouse embryo were observed on the light-sheet microscope. As the results, two photon images with high contrast and high spatial resolution were successfully obtained in the microscopy system. The system has multimodality, not only mutiphoton fluorescence imaging, but also hyperspectral imaging, which can be applicable to fluorescence unmixing analysis and Raman imaging. It enables to obtain high specific and high throughput molecular imaging in vivo and in vitro.

  18. Calibration and monitoring of the air fluorescence detector for the Telescope Array experiment

    NASA Astrophysics Data System (ADS)

    Tokuno, H.; Azuma, R.; Fukushima, M.; Higashide, Y.; Inoue, N.; Kadota, K.; Kakimoto, F.; Kawana, S.; Murano, Y.; Ogio, S.; Sakurai, N.; Sagawa, H.; Shibata, T.; Takeda, M.; Taketa, A.; Tameda, Y.; Tsunesada, Y.; Udo, S.; Yoshida, S.; Telescope Array Collaboration

    The air fluorescence detectors (FDs) of the Telescope Array (TA) experiment have been constructed in a dessert of Utah, USA. We can measure the longitudinal developments of EASs directly with the FDs by detecting air fluorescence lights and determine the primary energies of ultra-high energy cosmic rays. In order for accurate observation and measurements of EASs, elaborate detector calibrations and monitoring systems are required. We will present the result of calibration and monitoring systems for the reflectance and curvature radius of segment mirrors, the characteristics of PMT (absolute gain, linearity, temperature dependence of gain), and the uniformity of the camera surface, etc.

  19. Enhanced light collection in fluorescence microscopy using self-assembled micro-reflectors

    NASA Astrophysics Data System (ADS)

    Göröcs, Zoltán; McLeod, Euan; Ozcan, Aydogan

    2015-06-01

    In fluorescence microscopy, the signal-to-noise ratio (SNR) of the optical system is directly linked to the numerical aperture (NA) of the microscope objective, which creates detection challenges for low-NA, wide-field and high-throughput imaging systems. Here we demonstrate a method to increase the light collection efficiency from micron-scale fluorescent objects using self-assembled vapor-condensed polyethylene glycol droplets, which act as micro-reflectors for fluorescent light. Around each fluorescent particle, a liquid meniscus is formed that increases the excitation efficiency and redirects part of the laterally-emitted fluorescent light towards the detector due to internal reflections at the liquid-air interface of the meniscus. The three-dimensional shape of this micro-reflector can be tuned as a function of time, vapor temperature, and substrate contact angle, providing us optimized SNR performance for fluorescent detection. Based on these self-assembled micro-reflectors, we experimentally demonstrate ~2.5-3 fold enhancement of the fluorescent signal from 2-10 μm sized particles. A theoretical explanation of the formation rate and shapes of these micro-reflectors is presented, along with a ray tracing model of their optical performance. This method can be used as a sample preparation technique for consumer electronics-based microscopy and sensing tools, thus increasing the sensitivity of low-NA systems that image fluorescent micro-objects.

  20. Enhanced light collection in fluorescence microscopy using self-assembled micro-reflectors

    PubMed Central

    Göröcs, Zoltán; McLeod, Euan; Ozcan, Aydogan

    2015-01-01

    In fluorescence microscopy, the signal-to-noise ratio (SNR) of the optical system is directly linked to the numerical aperture (NA) of the microscope objective, which creates detection challenges for low-NA, wide-field and high-throughput imaging systems. Here we demonstrate a method to increase the light collection efficiency from micron-scale fluorescent objects using self-assembled vapor-condensed polyethylene glycol droplets, which act as micro-reflectors for fluorescent light. Around each fluorescent particle, a liquid meniscus is formed that increases the excitation efficiency and redirects part of the laterally-emitted fluorescent light towards the detector due to internal reflections at the liquid-air interface of the meniscus. The three-dimensional shape of this micro-reflector can be tuned as a function of time, vapor temperature, and substrate contact angle, providing us optimized SNR performance for fluorescent detection. Based on these self-assembled micro-reflectors, we experimentally demonstrate ~2.5-3 fold enhancement of the fluorescent signal from 2-10 μm sized particles. A theoretical explanation of the formation rate and shapes of these micro-reflectors is presented, along with a ray tracing model of their optical performance. This method can be used as a sample preparation technique for consumer electronics-based microscopy and sensing tools, thus increasing the sensitivity of low-NA systems that image fluorescent micro-objects. PMID:26083081

  1. Detail of window treatment, suspended radiators, and fluorescent lights, prop ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of window treatment, suspended radiators, and fluorescent lights, prop shop. View to east. - San Bernardino Valley College, Auditorium, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA

  2. Light emission from compound eye with conformal fluorescent coating

    NASA Astrophysics Data System (ADS)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2015-03-01

    Compound eyes of insects are attractive biological systems for engineered biomimicry as artificial sources of light, given their characteristic wide angular field of view. A blowfly eye was coated with a thin conformal fluorescent film, with the aim of achieving wide field-of-view emission. Experimental results showed that the coated eye emitted visible light and that the intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  3. Organimetallic Fluorescent Complex Polymers For Light Emitting Applications

    DOEpatents

    Shi, Song Q.; So, Franky

    1997-10-28

    A fluorescent complex polymer with fluorescent organometallic complexes connected by organic chain spacers is utilized in the fabrication of light emitting devices on a substantially transparent planar substrate by depositing a first conductive layer having p-type conductivity on the planar surface of the substrate, depositing a layer of a hole transporting and electron blocking material on the first conductive layer, depositing a layer of the fluorescent complex polymer on the layer of hole transporting and electron blocking material as an electron transporting emissive layer and depositing a second conductive layer having n-type conductivity on the layer of fluorescent complex polymer.

  4. New method of acne disease fluorescent diagnostics in natural and fluorescent light and treatment control

    NASA Astrophysics Data System (ADS)

    Karimova, L. N.; Berezin, A. N.; Shevchik, S. A.; Kharnas, S. S.; Kusmin, S. G.; Loschenov, V. B.

    2005-08-01

    In the given research the new method of fluorescent diagnostics (FD) and photodynamic therapy (PDT) control of acne disease is submitted. Method is based on simultaneous diagnostics in natural and fluorescent light. PDT was based on using 5-ALA (5- aminolevulinic acid) preparation and 600-730 nanometers radiation. If the examined site of a skin possessed a high endogenous porphyrin fluorescence level, PDT was carried out without 5-ALA. For FD and treatment control a dot spectroscopy and the fluorescent imaging of the affected skin were used.

  5. RNA Fluorescence with Light-Up Aptamers

    PubMed Central

    Ouellet, Jonathan

    2016-01-01

    Seeing is not only believing; it also includes understanding. Cellular imaging with GFP in live cells has been transformative in many research fields. Modulation of cellular regulation is tightly regulated and innovative imaging technologies contribute to further understand cellular signaling and physiology. New types of genetically encoded biosensors have been developed over the last decade. They are RNA aptamers that bind with their cognate fluorogen ligands and activate their fluorescence. The emergence and the evolution of these RNA aptamers as well as their conversion into a wide spectrum of applications are examined in a global way. PMID:27446908

  6. RNA Fluorescence with Light-Up Aptamers.

    PubMed

    Ouellet, Jonathan

    2016-01-01

    Seeing is not only believing; it also includes understanding. Cellular imaging with GFP in live cells has been transformative in many research fields. Modulation of cellular regulation is tightly regulated and innovative imaging technologies contribute to further understand cellular signaling and physiology. New types of genetically encoded biosensors have been developed over the last decade. They are RNA aptamers that bind with their cognate fluorogen ligands and activate their fluorescence. The emergence and the evolution of these RNA aptamers as well as their conversion into a wide spectrum of applications are examined in a global way. PMID:27446908

  7. The photosensitizing potential of compact fluorescent vs incandescent light bulbs.

    PubMed

    Chignell, Colin F; Sik, Robert H; Bilski, Piotr J

    2008-01-01

    Recently an article about the new energy-saving compact fluorescent light (CFL) bulbs appeared in Parade magazine [Rosenfeld, I. (2008) Parade Feb 3, 22]. Under the heading "Bright Lights, Bad Headache?" the writer states that "new research suggests some dangers" involving these lights because they are fluorescent and "can aggravate skin rashes in people with lups, eczema, dermatitis or porphyria." We measured the emission spectrum of a 14 W compact fluorescent bulb (with the same luminous flux as a 60 W incandescent bulb) and compared it to 60 W soft white incandescent and cool white fluorescent (CWF) bulbs. Our results clearly show that the spectral irradiance of the compact fluorescent bulb is similar to that of the CWF bulb; both exhibit sharp Hg emission lines at 365 nm (very weak), 404 nm (weak), 435 nm (moderate) and 543 nm (strong). In contrast, the emission of the incandescent bulb begins at 375 nm and then increases monotonically to above 750 nm. From their respective absorption spectra we calculated the potential photosensitization indices of protoporphyrin IX (PPIX; a prototypic porphyria skin photosensitizer) and riboflavin (a putative lens photosensitizer) vs 14 W compact fluorescent, CWF and 60 W incandescent bulbs. A higher photosensitization index would indicate a greater chance that the light/photosensitizer combination would cause photosensitization of the skin or eyes. We found that for PPIX and riboflavin the photosensitization index of the compact fluorescent bulb is less than half that of the 60 W incandescent bulb. These results suggest that substitution of a compact fluorescent bulb for an incandescent bulb of the same luminous flux should not increase the phototoxicity of skin porphyrins or lens riboflavin. PMID:18494761

  8. Acrodynia: exposure to mercury from fluorescent light bulbs

    SciTech Connect

    Tunnessen, W.W. Jr.; McMahon, K.J.; Baser, M.

    1987-05-01

    Medical attention was sought for a 23-month-old toddler because of anorexia, weight loss, irritability, profuse sweating, peeling and redness of his fingers and toes, and a miliarial rash. The diagnosis was mercury poisoning, and an investigation of his environment disclosed that he had been exposed to mercury from broken fluorescent light bulbs. Acrodynia resulting from fluorescent bulbs has not been previously reported.

  9. Benefits and Costs of Ultraviolet Fluorescent Lighting

    PubMed Central

    Lestina, Diane C.; Miller, Ted R.; Knoblauch, Richard; Nitzburg, Marcia

    1999-01-01

    Objective To demonstrate the improvements in detection and recognition distances using fluorescent roadway delineation and auxiliary ultra-violet (UVA) headlights and determine the reduction in crashes needed to recover increased costs of the UVA/flourescent technology. Methods Field study comparisons with and without UVA headlights. Crash types potentially reduced by UVA/flourescent technology were estimated using annual crash and injury incidence data from the General Estimates System (1995–1996) and the 1996 Fatality Analysis Reporting System. Crash costs were computed based on body region and threat-to-life injury severity. Results Significant improvements in detection and recognition distances for pedestrian scenarios, ranging from 34% to 117%. A 19% reduction in nighttime motor vehicle crashes involving pedestrians or pedal-cycles will pay for the additional UVA headlight costs. Alternatively, a 5.5% reduction in all relevant nighttime crashes will pay for the additional costs of UVA headlights and fluorescent highway paint combined. Conclusions If the increased detection and recognition distances resulting from using UVA/flourescent technology as shown in this field study reduce relevant crashes by even small percentages, the benefit cost ratios will still be greater than 2; thus, the UVA/flourescent technology is very cost-effective and a definite priority for crash reductions.

  10. Integrated ultrasonic particle positioning and low excitation light fluorescence imaging

    SciTech Connect

    Bernassau, A. L.; Al-Rawhani, M.; Beeley, J.; Cumming, D. R. S.

    2013-12-09

    A compact hybrid system has been developed to position and detect fluorescent micro-particles by combining a Single Photon Avalanche Diode (SPAD) imager with an acoustic manipulator. The detector comprises a SPAD array, light-emitting diode (LED), lenses, and optical filters. The acoustic device is formed of multiple transducers surrounding an octagonal cavity. By stimulating pairs of transducers simultaneously, an acoustic landscape is created causing fluorescent micro-particles to agglomerate into lines. The fluorescent pattern is excited by a low power LED and detected by the SPAD imager. Our technique combines particle manipulation and visualization in a compact, low power, portable setup.

  11. Integrated ultrasonic particle positioning and low excitation light fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Bernassau, A. L.; Al-Rawhani, M.; Beeley, J.; Cumming, D. R. S.

    2013-12-01

    A compact hybrid system has been developed to position and detect fluorescent micro-particles by combining a Single Photon Avalanche Diode (SPAD) imager with an acoustic manipulator. The detector comprises a SPAD array, light-emitting diode (LED), lenses, and optical filters. The acoustic device is formed of multiple transducers surrounding an octagonal cavity. By stimulating pairs of transducers simultaneously, an acoustic landscape is created causing fluorescent micro-particles to agglomerate into lines. The fluorescent pattern is excited by a low power LED and detected by the SPAD imager. Our technique combines particle manipulation and visualization in a compact, low power, portable setup.

  12. NOTE: Fluorescent light effects on FWT-60 radiochromic film

    NASA Astrophysics Data System (ADS)

    Butson, Martin J.; Cheung, Tsang; Yu, Peter K. N.

    2005-08-01

    FWT-60 radiochromic film has been tested for colouration effects from fluorescent light sources and shown to produce a marked colouration when exposed to office fluorescent light sources showing an approximate 1 OD unit per 0.5 J m-2 exposure to a broad ultraviolet (UV) UVA + UVB spectrum at the peak absorption wavelength. This produces a measurable and quantifiable response to UV exposure. By choosing an appropriate wavelength of readout or band pass, the level of sensitivity can be changed to match the application or exposure level measurement required. These levels of UV response are significantly higher in sensitivity than other radiochromic films such as Gafchromic MD-55 by an order of magnitude. This feature may be of use for measurement of integrated UV exposure from fluorescent lights when required and produces a quantifiable history of total exposure.

  13. Evaluation of Flat Microchannel Plate Photomultipliers for Use in a Portable Air Fluorescence Detector

    NASA Astrophysics Data System (ADS)

    Benzvi, S.; Martin, J.

    2003-07-01

    Future applications of the air fluorescence technique will require robust, portable detectors, versatile enough to be deployed in remote areas with little infrastructure. One such experiment is the Gamma Ray and Neutron Decay Scan of the Galaxy (GRaNDScan), which proposes to survey the EeV sky by observation of γ and cosmic ray air showers in the southern hemisphere. To view a 30° field at or exceeding a resolution of 1° , GRaNDScan will employ a lensless Schmidt optical system, with the light-sensitive element in each detector consisting of a spherical surface of tiled photomultipliers. Currently, the BURLE 85001 micro channel plate photomultiplier (MCP PMT), a low profile device appropriate for tiling, is the primary candidate for these cameras. In this paper, we discuss the preliminary design of the GRaNDScan optics, the basic characteristics of the 85001 photomultiplier, and the suitability of this device for use in a portable air fluorescence detector.

  14. Evaluation of premalignant and malignant lesions by fluorescent light (VELscope)

    PubMed Central

    Sawan, Dania; Mashlah, Ammar

    2015-01-01

    Aim: The purpose of this study was the early detection of premalignant and malignant oral soft lesions by fluorescent light (VELscope). Materials and Methods: A total of 748 patients were evaluated through clinical and fluorescent light analysis of the entire oral cavity. Any lesion that was detected underwent a surgical excision biopsy as the golden standard for the detection of the lesion's histology; then a comparison was made between the results to assure the efficacy of the fluorescent light analysis outcome. Results: About 9.4% of the lesions detected were abnormal lesions and 83.09% had loss of fluorescent light effect. Based on the use of surgical biopsy, the machine had a sensitivity of 74.1% and a specificity of 96.3%. According to the statistical analysis, the P value was much lower than 0.05, so we can conclude that at 95% confidence level, there was significant agreement between VELscope results and biopsy results. Kappa coefficient value was approximately 0.5, which means that the strength of the agreement was medium. Conclusion: VELscope can be used as a clinical diagnostic aid in the detection of premalignant and malignant lesions of the oral cavity. In addition, it helps in the detection of the borders in both surgical biopsy and surgical excision. PMID:26236687

  15. Delayed light emission and fluorescence responses of plants to chilling

    SciTech Connect

    Abbott, J.A.; Campbell, T.A.; Massie, D.R. . Agricultural Research Service)

    1994-01-01

    Delayed light emission (DLE) of chlorophyll has the same excitation and emission spectra as chlorophyll fluorescence and was formerly called delayed fluorescence. DLE has a much longer time response than true chlorophyll fluorescence and is detectable for times ranging from milliseconds to many minutes. DLE is induced by back reactions of the photosynthetic pathway and therefore requires functional chloroplasts. It is detectable only in the dark following light excitation, yields very low energy, and decays very rapidly. DLE repetitively excited over time, which they term refreshed DLE (RDLE), shows a shoulder and broad peak in the measurements, indicating participation of at least two energy pools. DLE is altered by physiological stresses that affect chloroplasts or photosynthesis, and as illustration, plant species known to be very susceptible or very tolerant to chilling were exposed to chilling temperatures for varying times. RDLE at 0.3 s (the initial shoulder on the curves) rose in response to chilling damage in the susceptible species. The major RDLE peak was greatly inhibited in the susceptible species and showed only small changes in the tolerant species. Fluorescence measurements made on the chilling-tolerant species indicated similar responses and similar coefficients of determination were derived. These results indicate that measurement of precisely timed delayed light emission or of refreshed delayed light emission at a less precisely controlled time can be used to detect chilling stress.

  16. Fluorescent photography of spray droplets using a laser light source

    NASA Technical Reports Server (NTRS)

    Groeneweg, J.; Hiroyasu, H.; Sowls, R.

    1969-01-01

    Monochromatic laser emission transformed by a fluorescent process into droplet emission over a wavelength band provides high light intensities for obtaining adequate time resolution to stop droplet motion in photographic spray studies. Experiments showed that the Q-switched laser-optical harmonic generator combination produced sharp, well-exposed droplet images.

  17. Three Dimensional Fluorescence Imaging Using Multiple Light-Sheet Microscopy

    PubMed Central

    Mohan, Kavya; Purnapatra, Subhajit B.; Mondal, Partha Pratim

    2014-01-01

    We developed a multiple light-sheet microscopy (MLSM) system capable of 3D fluorescence imaging. Employing spatial filter in the excitation arm of a SPIM system, we successfully generated multiple light-sheets. This improves upon the existing SPIM system and is capable of 3D volume imaging by simultaneously illuminating multiple planes in the sample. Theta detection geometry is employed for data acquisition from multiple specimen layers. This detection scheme inherits many advantages including, background reduction, cross-talk free fluorescence detection and high-resolution at long working distance. Using this technique, we generated equi-intense light-sheets of thickness approximately with an inter-sheet separation of . Moreover, the light-sheets generated by MLSM is found to be 2 times thinner than the state-of-art SPIM system. Imaging of fluorescently coated yeast cells of size (encaged in Agarose gel-matrix) is achieved. Proposed imaging technique may accelerate the field of fluorescence microscopy, cell biology and biophotonics. PMID:24911061

  18. High-intensity xenon pulse light source for fluorescence excitation

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueno, Kazuo

    1997-05-01

    A newly developed 60W xenon flash lamp, L6604 and L6605, achieves the goals of longer operating life, higher output, and improved light stability. It operates at 2 Joules per flash input energy with approximately a 4 microsecond flash duration. The stability achieved is 2-3 percent peak-to-peak during a lifetime of 5 X 10e7 flashes, which is almost double that of conventional xenon flash lamps. This newly developed xenon flashlamp should serve as an excellent light source for analytical cytology and other fluorescence instruments. It can function as a high output, stable excitation light source for conventional fluorescence or delayed luminescence with a CCD. Besides providing powerful and stable illumination for absorption analysis of cells on slides, this lamp eliminates the optical artifacts associated with vibration of the stage which often limit throughput. This paper will describe in detail performance improvements obtained from this newly developed xenon flash lamp.

  19. Air fluorescence detection of large air showers below the horizon

    NASA Technical Reports Server (NTRS)

    Halverson, P.; Bowen, T.

    1985-01-01

    In the interest of exploring the cosmic ray spectrum at energies greater than 10 to the 18th power eV, where flux rates at the Earth's surface drop below 100 yr(-1) km(-2) sr(-1), cosmic ray physicists have been forced to construct ever larger detectors in order to collect useful amounts of data in reasonable lengths of time. At present, the ultimate example of this trend is the Fly's Eye system in Utah, which uses the atmosphere around an array of skyward-looking photomultiplier tubes. The air acts as a scintillator to give detecting areas as large as 5000 square kilometers sr (for highest energy events). This experiment has revealed structure (and a possible cutoff) in the ultra-high energy region above 10 o the 19th power eV. The success of the Fly's Eye experiment provides impetus for continuing the development of larger detectors to make accessible even higher energies. However, due to the rapidly falling flux, a tenfold increase in observable energy would call for a hundredfold increase in the detecting area. But, the cost of expanding the Fly's Eye detecting area will approximately scale linearly with area. It is for these reasons that the authors have proposed a new approach to using the atmosphere as a scintillator; one which will require fewer photomultipliers, less hardware (thus being less extensive), yet will provide position and shower size information.

  20. Host Engineering for High Quantum Efficiency Blue and White Fluorescent Organic Light-Emitting Diodes.

    PubMed

    Song, Wook; Lee, Inho; Lee, Jun Yeob

    2015-08-01

    High quantum efficiency in blue and white fluorescence organic light-emitting diodes is achieved by developing a novel device architecture with fluorescent emitters doped in a thermally activated delayed fluorescent emitter as a host material. PMID:26078193

  1. Make caffeine visible: a fluorescent caffeine "traffic light" detector.

    PubMed

    Xu, Wang; Kim, Tae-Hyeong; Zhai, Duanting; Er, Jun Cheng; Zhang, Liyun; Kale, Anup Atul; Agrawalla, Bikram Keshari; Cho, Yoon-Kyoung; Chang, Young-Tae

    2013-01-01

    Caffeine has attracted abundant attention due to its extensive existence in beverages and medicines. However, to detect it sensitively and conveniently remains a challenge, especially in resource-limited regions. Here we report a novel aqueous phase fluorescent caffeine sensor named Caffeine Orange which exhibits 250-fold fluorescence enhancement upon caffeine activation and high selectivity. Nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy indicate that π-stacking and hydrogen-bonding contribute to their interactions while dynamic light scattering and transmission electron microscopy experiments demonstrate the change of Caffeine Orange ambient environment induces its fluorescence emission. To utilize this probe in real life, we developed a non-toxic caffeine detection kit and tested it for caffeine quantification in various beverages. Naked-eye sensing of various caffeine concentrations was possible based on color changes upon irradiation with a laser pointer. Lastly, we performed the whole system on a microfluidic device to make caffeine detection quick, sensitive and automated. PMID:23877095

  2. Blue-green phosphor for fluorescent lighting applications

    DOEpatents

    Srivastava, Alok; Comanzo, Holly; Manivannan, Venkatesan; Setlur, Anant Achyut

    2005-03-15

    A fluorescent lamp including a phosphor layer including Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ (SAE) and at least one of each of a red, green and blue emitting phosphor. The phosphor layer can optionally include an additional, deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of SAE in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over, the course of the lamp life.

  3. Affective and cognitive reactions to subliminal flicker from fluorescent lighting.

    PubMed

    Knez, Igor

    2014-05-01

    This study renews the classical concept of subliminal perception (Peirce & Jastrow, 1884) by investigating the impact of subliminal flicker from fluorescent lighting on affect and cognitive performance. It was predicted that low compared to high frequency lighting (latter compared to former emits non-flickering light) would evoke larger changes in affective states and also impair cognitive performance. Subjects reported high rather than low frequency lighting to be more pleasant, which, in turn, enhanced their problem solving performance. This suggests that sensory processing can take place outside of conscious awareness resulting in conscious emotional consequences; indicating a role of affect in subliminal/implicit perception, and that positive affect may facilitate cognitive task performance. PMID:24685568

  4. Spectroscopic Analysis of Today's Compact Fluorescent Light Bulbs

    NASA Astrophysics Data System (ADS)

    Pluhar, Edward

    2012-03-01

    In today's consumer market, there are many different light bulbs that claim to produce `natural' light. In my research, I both quantitatively and qualitatively analyzed this claim. First, utilizing a spectroscope, I compared the spectra emitted by different brands and types of compact fluorescent light (CFL) bulbs to the spectra emitted by the Sun. Once the bulbs were quantitatively analyzed, I proceeded to qualitatively analyze them by exposing subjects to the different bulbs. The subjects were asked to rate the quality of color in different pictures illuminated by each type of CFL. From these tests, I was able to determine the ``best'' CFL bulbs, and conclude whether the health risks associated with CFL bulbs outweigh the cost savings, longevity of the bulbs, and/or quality of light benefits.

  5. The instantaneous light-intensity function of a fluorescent lamp

    NASA Astrophysics Data System (ADS)

    Gluskin, Emanuel; Topalis, Frangiskos V.; Kateri, Ifigenia; Bisketzis, Nikolas

    2006-05-01

    Using some simple physics and “system” considerations, the instantaneous light intensity function ψ(t) of a fluorescent lamp fed via a regular ballast from the 50 60 Hz line is argued to be ψ(t)=ψ+bp(t), where p(t) is the instantaneous power function of the lamp, and b is a constant, and experiment confirms this formula well. The main frequency of ψ(t), the very significant singularity of its waveform, and the relative intensity of the ripple, i.e., the depth of the modulation, are the focus. The results are important for research into the vision problem that some humans (autistic, but others, too) experience regarding fluorescent light. The inertia of the processes in the lamp which are responsible for the light emission, provides some nonzero emission at the instants when p(t) has zeros. The smaller the volume of the tube and the mass of the gas are, the more weakly the inertia of the processes is expressed, and the relatively smaller is ψ. However, it should be very difficult to theoretically obtain ψ(t), in particular ψ, from the very complicated physics of the low-pressure discharge in the tube. We conclude that ψ has to be connected with the (also easily measured) lamp's inductance. The work should attract more attention of the physicists to the properties of the common fluorescent lamps.

  6. Remediation plan for fluorescent light fixtures containing polychlorinated biphenyls (PCBs)

    SciTech Connect

    1992-04-30

    This report describes the remedial action to achieve compliance with 29 CFR 1910 Occupational Safety and Health Administration (OSHA) requirements of fluorescent light fixtures containing PCBs at K-25 site. This remedial action is called the Remediation Plan for Fluorescent Light Fixtures Containing PCBs at the K-25 Site (The Plan). The Plan specifically discusses (1) conditions of non-compliance, (2) alternative solutions, (3) recommended solution, (4) remediation plan costs, (5) corrective action, (6) disposal of PCB waste, (7) training, and (8) plan conclusions. The results from inspections by Energy Systems personnel in 2 buildings at K-25 site and statistical extension of this data to 91 selected buildings at the K-25 site indicates that there are approximately 28,000 fluorescent light fixtures containing 47,036 ballasts. Approximately 38,531 contain PCBs and 2,799 of the 38,531 ballasts are leaking PCBs. Review of reportable occurrences at K-25 for the 12 month period of September 1990 through August 1991 shows that Energy Systems personnel reported 69 ballasts leaking PCBs. Each leaking ballast is in non-compliance with 29 CFR 1910 - Table Z-1-A. The age of the K-25 facilities indicate a continued and potential increase in ballasts leaking PCBs. This report considers 4 alternative solutions for dealing with the ballasts leaking PCBs. The advantages and disadvantages of each alternative solution are discussed and ranked using cost of remediation, reduction of health risks, and compliance with OSHA as criteria.

  7. Effects of light intensity light quality and air velocity on temperature in plant reproductive organs

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.

    Excess temperature increase in plant reproductive organs such as anthers and stigmata could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions in closed plant growth facilities There is a possibility that the aberration was caused by an excess increase in temperatures of reproductive organs in Bioregenerative Life Support Systems under microgravity conditions in space The fundamental study was conducted to know the thermal situation of the plant reproductive organs as affected by light intensity light quality and air velocity on the earth and to estimate the excess temperature increase in the reproductive organs in closed plant growth facilities in space Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at an air temperature of 10 r C The temperatures in flowers at 300 mu mol m -2 s -1 PPFD under the lights from red LEDs white LEDs blue LEDs fluorescent lamps and incandescent lamps increased by 1 4 1 7 1 9 6 0 and 25 3 r C respectively for rice and by 2 8 3 4 4 1 7 8 and 43 4 r C respectively for strawberry The flower temperatures increased with increasing PPFD levels The temperatures in petals anthers and stigmas of strawberry at 300 mu mol m -2 s -1 PPFD under incandescent lamps increased by 32 7 29 0 and 26 6 r C respectively at 0 1 m s -1 air velocity and by 20 6 18 5 and 15 9 r C respectively at 0 8 m s -1 air velocity The temperatures of reproductive organs decreased with increasing

  8. Development of a High Output Fluorescent Light Module for the Commercial Plant Biotechnology Facility

    NASA Technical Reports Server (NTRS)

    Turner, Mark; Zhou, Wei-Jia; Doty, Laura (Technical Monitor)

    2000-01-01

    To maximize the use of available resources provided onboard the International Space Station, the development of an efficient lighting 1 system is critical to the overall performance of the CPBF. Not only is it important to efficiently generate photon energy, but thermal loads on the CPBF Temperature and Humidity Control System must be minimized. By utilizing optical coatings designed to produce highly diffuse reflectance in the visible wavelengths while minimizing reflectance in the infrared region, the design of the fluorescent light module for the CPBF is optimized for maximum photon flux, spatial uniformity and energy efficiency. Since the Fluorescent Light Module must be fully enclosed to meet (ISS) requirements for containment of particulates and toxic materials, heat removal from the lights presented some unique design challenges. By using the Express Rack moderate C, temperature-cooling loop, heat is rejected by means of a liquid/air coolant manifold. Heat transfer to the manifold is performed by conduction using copper fins, by forced air convection using miniature fans, and by radiation using optically selective coatings that absorb in the infrared wavelengths. Using this combination of heat transfer mechanisms builds in redundancy to prevent thermal build up and premature bulb failure.

  9. Infrared imaging of LED lighting tubes and fluorescent tubes

    NASA Astrophysics Data System (ADS)

    Siikanen, Sami; Kivi, Sini; Kauppinen, Timo; Juuti, Mikko

    2011-05-01

    The low energy efficiency of conventional light sources is mainly caused by generation of waste heat. We used infrared (IR) imaging in order to monitor the heating of both LED tube luminaires and ordinary T8 fluorescent tubes. The IR images showed clearly how the surface temperatures of the fluorescent tube ends quickly rose up to about +50...+70°C, whereas the highest surface temperatures seen on the LED tubes were only about +30...+40°C. The IR images demonstrated how the heat produced by the individual LED chips can be efficiently guided to the supporting structure in order to keep the LED emitters cool and hence maintain efficient operation. The consumed electrical power and produced illuminance were also recorded during 24 hour measurements. In order to assess the total luminous efficacy of the luminaires, separate luminous flux measurements were made in a large integrating sphere. The currently available LED tubes showed efficacies of up to 88 lm/W, whereas a standard "cool white" T8 fluorescent tube produced ca. 75 lm/W. Both lamp types gave ca. 110 - 130 lx right below the ceiling-mounted luminaire, but the LED tubes consume only 40 - 55% of the electric power compared to fluorescent tubes.

  10. Structured light illumination for extended resolution in fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Fedosseev, R.; Belyaev, Y.; Frohn, J.; Stemmer, A.

    2005-03-01

    During the last two decades fluorescence microscopy has become a powerful experimental tool in modern biology. Resolution of optical microscopes is limited by the diffraction nature of light and amounts to approximately 200 nm for point objects imaged with green light and high-NA objectives. Recently, several successful attempts have been made to break the resolution limit of microscopes. One of them is the so-called harmonic excitation light microscopy. 2D structured illumination produced by four interfering laser beams improves the lateral resolution by a factor of 2 to reach 100 nm. Structured illumination extends optical resolution since spatial frequencies beyond the classical cut-off frequency are brought into the passband of the optical microscope by frequency mixing. The extended passband is reconstructed computationally from several images acquired with shifted illumination patterns. Here we discuss an extension towards high resolution imaging of thick specimens by combining 2D structured illumination with deconvolution techniques.

  11. Spectral conversion with fluorescent microspheres for light emitting diodes.

    PubMed

    Hui, K N; Lai, P T; Choi, H W

    2008-01-01

    An innovative spectral conversion scheme for light emitting diodes using fluorescent microspheres has been demonstrated. An optimally mixed proportion of green and red fluorescent microspheres were coated onto a high-extraction-efficiency GaN micro-LED with emission centred at 470 nm. The microspheres self-assemble into ordered hexagonally arrays, forming regular and uniform coating layers. Devices with cool and warm white emission were achieved. The bluish-white LED has a luminous efficacy of 27.3 lm/W (at 20 mA) with CIE coordinates of (0.26, 0.28) and 8500K CCT, while the yellowish-white LED has a luminous efficacy of 26.67 lm/W (at 20 mA) with CIE coordinates of (0.36, 0.43) and 13000K CCT. PMID:18521128

  12. Blue fluorescent organic light emitting diodes with multilayered graphene anode

    SciTech Connect

    Hwang, Joohyun; Choi, Hong Kyw; Moon, Jaehyun; Shin, Jin-Wook; Joo, Chul Woong; Han, Jun-Han; Cho, Doo-Hee; Huh, Jin Woo; Choi, Sung-Yool; Lee, Jeong-Ik; Chu, Hye Yong

    2012-10-15

    As an innovative anode for organic light emitting devices (OLEDs), we have investigated graphene films. Graphene has importance due to its huge potential in flexible OLED applications. In this work, graphene films have been catalytically grown and transferred to the glass substrate for OLED fabrications. We have successfully fabricated 2 mm × 2 mm device area blue fluorescent OLEDs with graphene anodes which showed 2.1% of external quantum efficiency at 1000 cd/m{sup 2}. This is the highest value reported among fluorescent OLEDs using graphene anodes. Oxygen plasma treatment on graphene has been found to improve hole injections in low voltage regime, which has been interpreted as oxygen plasma induced work function modification. However, plasma treatment also increases the sheet resistance of graphene, limiting the maximum luminance. In summary, our works demonstrate the practical possibility of graphene as an anode material for OLEDs and suggest a processing route which can be applied to various graphene related devices.

  13. Light sheet fluorescence microscopy (LSFM): past, present and future.

    PubMed

    Lim, John; Lee, Hwee Kuan; Yu, Weimiao; Ahmed, Sohail

    2014-10-01

    Light sheet fluorescence microscopy (LSFM) has emerged as an important imaging modality to follow biology in live 3D samples over time with reduced phototoxicity and photobleaching. In particular, LSFM has been instrumental in revealing the detail of early embryonic development of Zebrafish, Drosophila, and C. elegans. Open access projects, DIY-SPIM, OpenSPIM, and OpenSPIN, now allow LSFM to be set-up easily and at low cost. The aim of this paper is to facilitate the set-up and use of LSFM by reviewing and comparing open access projects, image processing tools and future challenges. PMID:25118817

  14. Diagnosis of dental caries using quantitative light-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Amaechi, Bennett T.; Higham, Susan M.

    2001-10-01

    Current dental diagnostic methods can detect caries but cannot quantify the mineral status of the lesion. Quantitative Light-induced Fluorescence (QLF) measures the percentage fluorescence radiance change of demineralised enamel with respect to surround sound enamel, and related it directly to the amount of mineral lost during demineralisation. Demineralisation of teeth to produce caries-like lesions and the subsequent remineralisation of the lesions were monitored quantitatively and longitudinally with QLF. The influence of factors such as presence of plaque or saliva, lesion staining, lesion magnification, tooth thickness and developmental hypomineralisation, on the reproducibility of QLF imaging and analysis were investigated, Results showed that the integrated fluorescence change (hence the mineral loss) increased linearly with demineralisation time and decreased with increasing remineralisation time. Caries detection was limited by saliva or plaque, but enhanced by staining. QLF could not discriminate between developmental hypomineralisation and caries. Neither the variation in tooth thickness nor lesion magnification within the limit of a sharp image made a significant difference in QLF analysis. It was concluded that QLF could detect and quantitatively monitor the mineral changes in an incipient caries on a longitudinal basis, however detection may be limited by the presence of saliva or plaque or enhanced by staining.

  15. Light, Colour & Air Quality: Important Elements of the Learning Environment?

    ERIC Educational Resources Information Center

    Hathaway, Warren E.

    1987-01-01

    Reviews and evaluates studies of the effects of light, color, and air quality on the learning environment. Concludes that studies suggest a role for light in establishing and maintaining physiological functions and balances and a need for improved air quality in airtight, energy efficient buildings. (JHZ)

  16. Shedding light on azopolymer brush dynamics by fluorescence correlation spectroscopy.

    PubMed

    Kollarigowda, R H; De Santo, I; Rianna, C; Fedele, C; Manikas, A C; Cavalli, S; Netti, P A

    2016-09-14

    Understanding the response to illumination at a molecular level as well as characterising polymer brush dynamics are key features that guide the engineering of new light-stimuli responsive materials. Here, we report on the use of a confocal microscopy technique that was exploited to discern how a single molecular event such as the photoinduced isomerisation of azobenzene can affect an entire polymeric material at a macroscopic level leading to photodriven mass-migration. For this reason, a set of polymer brushes, containing azobenzene (Disperse Red 1, DR) on the side chains of poly(methacrylic acid), was synthesised and the influence of DR on the polymer brush dynamics was investigated for the first time by Fluorescence Correlation Spectroscopy (FCS). Briefly, two dynamics were observed, a short one coming from the isomerisation of DR and a long one related to the brush main chain. Interestingly, photoinduced polymer aggregation in the confocal volume was observed. PMID:27491890

  17. Engineering light-emitting diode surgical light for near-infrared fluorescence image-guided surgical systems

    PubMed Central

    Zhu, Nan; Mondal, Suman; Gao, Shengkui; Achilefu, Samuel; Gruev, Viktor; Liang, Rongguang

    2014-01-01

    Abstract. The near-infrared (NIR) fluorescence signal in the 700 to 900 nm from molecular probes used in fluorescence image-guided surgery (FIGS) is usually weak compared to the NIR component from white light-emitting diode surgical light, which is typically switched off during FIGS to enhance the molecular fluorescence contrast of the image. We propose a simple solution to this critical issue in FIGS by removing NIR light from surgical light with a low cost commercial 3M cool mirror film 330. PMID:25057962

  18. Using Light Sheet Fluorescence Microscopy to Image Zebrafish Eye Development.

    PubMed

    Icha, Jaroslav; Schmied, Christopher; Sidhaye, Jaydeep; Tomancak, Pavel; Preibisch, Stephan; Norden, Caren

    2016-01-01

    Light sheet fluorescence microscopy (LSFM) is gaining more and more popularity as a method to image embryonic development. The main advantages of LSFM compared to confocal systems are its low phototoxicity, gentle mounting strategies, fast acquisition with high signal to noise ratio and the possibility of imaging samples from various angles (views) for long periods of time. Imaging from multiple views unleashes the full potential of LSFM, but at the same time it can create terabyte-sized datasets. Processing such datasets is the biggest challenge of using LSFM. In this protocol we outline some solutions to this problem. Until recently, LSFM was mostly performed in laboratories that had the expertise to build and operate their own light sheet microscopes. However, in the last three years several commercial implementations of LSFM became available, which are multipurpose and easy to use for any developmental biologist. This article is primarily directed to those researchers, who are not LSFM technology developers, but want to employ LSFM as a tool to answer specific developmental biology questions. Here, we use imaging of zebrafish eye development as an example to introduce the reader to LSFM technology and we demonstrate applications of LSFM across multiple spatial and temporal scales. This article describes a complete experimental protocol starting with the mounting of zebrafish embryos for LSFM. We then outline the options for imaging using the commercially available light sheet microscope. Importantly, we also explain a pipeline for subsequent registration and fusion of multiview datasets using an open source solution implemented as a Fiji plugin. While this protocol focuses on imaging the developing zebrafish eye and processing data from a particular imaging setup, most of the insights and troubleshooting suggestions presented here are of general use and the protocol can be adapted to a variety of light sheet microscopy experiments. PMID:27167079

  19. Using Light Sheet Fluorescence Microscopy to Image Zebrafish Eye Development

    PubMed Central

    Sidhaye, Jaydeep; Tomancak, Pavel; Preibisch, Stephan; Norden, Caren

    2016-01-01

    Light sheet fluorescence microscopy (LSFM) is gaining more and more popularity as a method to image embryonic development. The main advantages of LSFM compared to confocal systems are its low phototoxicity, gentle mounting strategies, fast acquisition with high signal to noise ratio and the possibility of imaging samples from various angles (views) for long periods of time. Imaging from multiple views unleashes the full potential of LSFM, but at the same time it can create terabyte-sized datasets. Processing such datasets is the biggest challenge of using LSFM. In this protocol we outline some solutions to this problem. Until recently, LSFM was mostly performed in laboratories that had the expertise to build and operate their own light sheet microscopes. However, in the last three years several commercial implementations of LSFM became available, which are multipurpose and easy to use for any developmental biologist. This article is primarily directed to those researchers, who are not LSFM technology developers, but want to employ LSFM as a tool to answer specific developmental biology questions. Here, we use imaging of zebrafish eye development as an example to introduce the reader to LSFM technology and we demonstrate applications of LSFM across multiple spatial and temporal scales. This article describes a complete experimental protocol starting with the mounting of zebrafish embryos for LSFM. We then outline the options for imaging using the commercially available light sheet microscope. Importantly, we also explain a pipeline for subsequent registration and fusion of multiview datasets using an open source solution implemented as a Fiji plugin. While this protocol focuses on imaging the developing zebrafish eye and processing data from a particular imaging setup, most of the insights and troubleshooting suggestions presented here are of general use and the protocol can be adapted to a variety of light sheet microscopy experiments. PMID:27167079

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

    SciTech Connect

    Lin, Jiang

    2002-04-11

    Lighting has been one of the fastest growing electric end-uses in China over the last twenty years, with an average annual growth rate of 14%. Fluorescent lighting provides a significant portion of China's lighting need. In 1998, China produced 680 million fluorescent lamps, of which 420 million were linear fluorescent lamps of various diameters (T8 to 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 efficiency standards to promote the adoption of more efficient fluorescent lamps in China. This paper analyzes China's proposed minimum efficiency standard for fluorescent lamps and presents an assessment of its likely impacts on China's lighting energy consumption and GHG emissions.

  1. Compact fluorescent lighting in Wisconsin: elevated atmospheric emission and landfill deposition post-EISA implementation.

    PubMed

    Arendt, John D; Katers, John F

    2013-07-01

    The majority of states in the USA, including Wisconsin, have been affected by elevated air, soil and waterborne mercury levels. Health risks associated with mercury increase from the consumption of larger fish species, such as Walleye or Pike, which bio-accumulate mercury in muscle tissue. Federal legislation with the 2011 Mercury and Air Toxics Standards and the Wisconsin legislation on mercury, 2009 Wisconsin Act 44, continue to aim at lowering allowable levels of mercury emissions. Meanwhile, mercury-containing compact fluorescent lights (CFL) sales continue to grow as businesses and consumers move away from energy intensive incandescent light bulbs. An exchange in pollution media is occurring as airborne mercury emissions from coal-burning power plants, the largest anthropogenic source of mercury, are being reduced by lower energy demand and standards, while more universal solid waste containing mercury is generated each time a CFL is disposed. The treatment of CFLs as a 'universal waste' by the Environmental Protection Agency (EPA) led to the banning of non-household fluorescent bulbs from most municipal solid waste. Although the EPA encourages recycling of bulbs, industry currently recycles fluorescent lamps and CFLs at a rate of only 29%. Monitoring programs at the federal and state level have had only marginal success with industrial and business CFL recycling. The consumer recycling rate is even lower at only 2%. A projected increase in residential CFL use in Wisconsin owing to the ramifications of the Energy Independence and Security Act of 2007 will lead to elevated atmospheric mercury and landfill deposition in Wisconsin. PMID:23635464

  2. Understanding the Fluorescence of TADF Light-Emitting Dyes.

    PubMed

    Valchanov, Georgi; Ivanova, Anela; Tadjer, Alia; Chercka, Dennis; Baumgarten, Martin

    2016-09-01

    In order to afford in a controlled fashion fine-tuning of the color and the intensity of the emitted light of potential fluorophores for organic light-emitting diodes (OLED), directed molecular design based on a donor-spacer-acceptor model is undertaken. One way of increasing emission efficiency is triplet harvesting. This can be achieved by thermally activated delayed fluorescence (TADF) when triplet and singlet excited states are quasi degenerate. Molecular building units are selected and bound in a specific pattern to allow for increase in emission performance, also due to TADF. Using time-dependent density functional theory, the relevant singlet-singlet and triplet-singlet energy gaps corresponding to absorption or emission transitions of the compounds are computed to simulate the electroluminescent spectrum. The results are analyzed in depth and relations between some spectral and structural properties are proposed. The best suited molecules are delineated as potential OLED building blocks. Guidelines for systematic improvement of the molecular characteristics are outlined. PMID:27529727

  3. Light emitting diode-based nanosecond ultraviolet light source for fluorescence lifetime measurements

    NASA Astrophysics Data System (ADS)

    Araki, Tsutomu; Misawa, Hiroaki

    1995-12-01

    A compact pulsed-light source is devised from an InGaN/AlGaN double heterostructure light-emitting diode (LED). The LED emits a 450-nm (blue) light under conventional dc operation below 30 mA. When a current larger than 50 mA is applied, the intensity of the 450-nm light saturates, but that of the 380-nm light due to the InGaN component continues to increase. This phenomenon is utilized to realize a nanosecond ultraviolet (UV) light source. Under repetitive, large current pulsing (frequency=10 kHz, pulse width=4 ns, peak current=2 A), the peak LED emission shifts from 450 to 380 nm. Intense light pulses (peak value=40 mW) of 4-ns duration were generated. To evaluate the potential of the pulsed LED as an excitation source, the fluorescence lifetime of a quinine-sulfate solution was measured. The observed lifetime characteristics agreed well with the generally accepted behavior.

  4. Comparison of milk oxidation by exposure to LED and fluorescent light.

    PubMed

    Brothersen, C; McMahon, D J; Legako, J; Martini, S

    2016-04-01

    Light-induced oxidation of milk has been well studied. Exposure of milk to UV light facilitates the oxidation of fats to aldehydes, and the degradation of sulfur-containing amino acids, both of which contribute to off-flavors. In addition, vitamin A and riboflavin are easily degraded by UV light. These reactions occur rapidly and are exacerbated by bright fluorescent lights in retail dairy cases. The invention of white light-emitting diodes (LED) may provide a solution to this oxidation problem. In this study, fresh milk containing 1% fat and fortified with vitamin A and riboflavin was exposed to LED at 4,000 lx, or fluorescent light at 2,200 lx for 24 h. Milk samples exposed to LED or fluorescent light, as well as milk protected from light, were analyzed by a consumer acceptance panel, and a trained flavor panel. In addition, vitamin A, riboflavin, and the production of volatile compounds were quantified. Exposure to light resulted in a reduction of cooked/sweet, milkfat, and sweet flavors and increased the intensity of butterscotch, cardboard, and astringency. In general, exposure to fluorescent light resulted in greater changes in the milk than exposure to LED even though the LED was at higher intensity. Consumers were able detect off-flavors in milk exposed to fluorescent light after 12 h and LED after 24 h of exposure. The riboflavin and vitamin A content was reduced by exposure to fluorescent light, whereas there was no significant reduction caused by LED compared with the non-light-exposed control. Production of hexanal, heptanal, 2-heptanal, octanal, 2-octanal nonanal, dimethyl sulfide, and caproic acid vinyl ester from the light-induced degradation of fats was significantly higher with fluorescent than LED. Production of these compounds was significantly higher with both light treatments than in the control milk. This study indicates that LED is less destructive to milk than fluorescent light. PMID:26874418

  5. Fluorescence particle detector for real-time quantification of viable organisms in air

    NASA Astrophysics Data System (ADS)

    Luoma, Greg; Cherrier, Pierre P.; Piccioni, Marc; Tanton, Carol; Herz, Steve; DeFreez, Richard K.; Potter, Michael; Girvin, Kenneth L.; Whitney, Ronald

    2002-02-01

    The ability to detect viable organisms in air in real time is important in a number of applications. Detecting high levels of airborne organisms in hospitals can prevent post-operative infections and the spread of diseases. Monitoring levels of airborne viable organisms in pharmaceutical facilities can ensure safe production of drugs or vaccines. Monitoring airborne bacterial levels in meat processing plants can help to prevent contamination of food products. Monitoring the level of airborne organisms in bio-containment facilities can ensure that proper procedures are being followed. Finally, detecting viable organisms in real time is a key to defending against biological agent attacks. This presentation describes the development and performance of a detector, based on fluorescence particle counting technology, where an ultraviolet laser is used to count particles by light scattering and elicit fluorescence from specific biomolecules found only in living organisms. The resulting detector can specifically detect airborne particles containing living organisms from among the large majority of other particles normally present in air. Efforts to develop the core sensor technology, focusing on integrating an UV laser with a specially designed particle-counting cell will be highlighted. The hardware/software used to capture the information from the sensor, provide an alarm in the presence of an unusual biological aerosol content will also be described. Finally, results from experiments to test the performance of the detector will be presented.

  6. Monitoring of Apoptosis in 3D Cell Cultures by FRET and Light Sheet Fluorescence Microscopy

    PubMed Central

    Weber, Petra; Schickinger, Sarah; Wagner, Michael; Angres, Brigitte; Bruns, Thomas; Schneckenburger, Herbert

    2015-01-01

    Non-radiative cell membrane associated Förster Resonance Energy Transfer (FRET) from an enhanced cyan fluorescent protein (ECFP) to an enhanced yellow fluorescent protein (EYFP) is used for detection of apoptosis in 3-dimensional cell cultures. FRET is visualized in multi-cellular tumor spheroids by light sheet based fluorescence microscopy in combination with microspectral analysis and fluorescence lifetime imaging (FLIM). Upon application of staurosporine and to some extent after treatment with phorbol-12-myristate-13-acetate (PMA), a specific activator of protein kinase c, the caspase-3 sensitive peptide linker DEVD is cleaved. This results in a reduction of acceptor (EYFP) fluorescence as well as a prolongation of the fluorescence lifetime of the donor (ECFP). Fluorescence spectra and lifetimes may, therefore, be used for monitoring of apoptosis in a realistic 3-dimensional system, while light sheet based microscopy appears appropriate for 3D imaging at low light exposure. PMID:25761242

  7. Physically-based in silico light sheet microscopy for visualizing fluorescent brain models

    PubMed Central

    2015-01-01

    Background We present a physically-based computational model of the light sheet fluorescence microscope (LSFM). Based on Monte Carlo ray tracing and geometric optics, our method simulates the operational aspects and image formation process of the LSFM. This simulated, in silico LSFM creates synthetic images of digital fluorescent specimens that can resemble those generated by a real LSFM, as opposed to established visualization methods producing visually-plausible images. We also propose an accurate fluorescence rendering model which takes into account the intrinsic characteristics of fluorescent dyes to simulate the light interaction with fluorescent biological specimen. Results We demonstrate first results of our visualization pipeline to a simplified brain tissue model reconstructed from the somatosensory cortex of a young rat. The modeling aspects of the LSFM units are qualitatively analysed, and the results of the fluorescence model were quantitatively validated against the fluorescence brightness equation and characteristic emission spectra of different fluorescent dyes. AMS subject classification Modelling and simulation PMID:26329404

  8. High-efficiency organic light-emitting diodes with fluorescent emitters

    NASA Astrophysics Data System (ADS)

    Nakanotani, Hajime; Higuchi, Takahiro; Furukawa, Taro; Masui, Kensuke; Morimoto, Kei; Numata, Masaki; Tanaka, Hiroyuki; Sagara, Yuta; Yasuda, Takuma; Adachi, Chihaya

    2014-05-01

    Fluorescence-based organic light-emitting diodes have continued to attract interest because of their long operational lifetimes, high colour purity of electroluminescence and potential to be manufactured at low cost in next-generation full-colour display and lighting applications. In fluorescent molecules, however, the exciton production efficiency is limited to 25% due to the deactivation of triplet excitons. Here we report fluorescence-based organic light-emitting diodes that realize external quantum efficiencies as high as 13.4-18% for blue, green, yellow and red emission, indicating that the exciton production efficiency reached nearly 100%. The high performance is enabled by utilization of thermally activated delayed fluorescence molecules as assistant dopants that permit efficient transfer of all electrically generated singlet and triplet excitons from the assistant dopants to the fluorescent emitters. Organic light-emitting diodes employing this exciton harvesting process provide freedom for the selection of emitters from a wide variety of conventional fluorescent molecules.

  9. Effect of Clouds on Apertures of Space-based Air Fluorescence Detectors

    NASA Technical Reports Server (NTRS)

    Sokolsky, P.; Krizmanic, J.

    2003-01-01

    Space-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibility of using IR remote sensing data from MODIS and GOES satellites to delimit clear areas of the atmosphere. The efficiency for detecting ultra-high-energy cosmic rays whose showers do not intersect clouds is determined for real, night-time cloud scenes. We use the MODIS SST cloud mask product to define clear pixels for cloud scenes along the equator and use the OWL Monte Carlo to generate showers in the cloud scenes. We find the efficiency for cloud-free showers with closest approach of three pixels to a cloudy pixel is 6.5% exclusive of other factors. We conclude that defining a totally cloud-free aperture reduces the sensitivity of space-based fluorescence detectors to unacceptably small levels.

  10. Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue.

    PubMed

    Lyndby, Niclas H; Kühl, Michael; Wangpraseurt, Daniel

    2016-01-01

    Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating. PMID:27225857

  11. Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue

    NASA Astrophysics Data System (ADS)

    Lyndby, Niclas H.; Kühl, Michael; Wangpraseurt, Daniel

    2016-05-01

    Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating.

  12. Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue

    PubMed Central

    Lyndby, Niclas H.; Kühl, Michael; Wangpraseurt, Daniel

    2016-01-01

    Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating. PMID:27225857

  13. Improved micro x-ray fluorescence spectrometer for light element analysis

    SciTech Connect

    Smolek, Stephan; Streli, Christina; Zoeger, Norbert; Wobrauschek, Peter

    2010-05-15

    Since most available micro x-ray fluorescence (micro-XRF) spectrometers operate in air, which does not allow the analysis of low-Z elements (Z{<=}14), a special micro-XRF spectrometer has been designed to extend the analytical range down to light elements (Z{>=}6). It offers improved excitation and detection conditions necessary for light element analysis. To eliminate absorption of the exciting and fluorescent radiation, the system operates under vacuum condition. Sample mapping is automated and controlled by specialized computer software developed for this spectrometer. Several different samples were measured to test and characterize the spectrometer. The spot size has been determined by scans across a 10 {mu}m Cu wire which resulted in a full width at half maximum of 31 {mu}m for Mo K{alpha} line (17.44 keV) and 44 {mu}m effective beam size for the Cu K edge and 71 {mu}m effective beam size for the Cu L edge. Lower limits of detection in the picogram range for each spot (or {mu}g/cm{sup 2}) were obtained by measuring various thin metal foils under different conditions. Furthermore, detection limits in the parts per million range were found measuring NIST621 standard reference material. Area scans of a microscopic laser print and NaF droplet were performed to show mapping capabilities.

  14. Fluorescent property of indocyanine green (ICG) rubber ring using LED and laser light sources.

    PubMed

    Hong, Nha Young; Kim, Hong Rae; Lee, Hyun Min; Sohn, Dae Kyung; Kim, Kwang Gi

    2016-05-01

    Fluorescent properties of ICG depends on solvent. Fluorescent characteristics of ICG rubber rings and optimized detection system condition were identified. The fluorescent rubber rings are produced by drying mixture of ICG solution and liquid rubber. LED and laser light sources were used to test differences between them. Other variables are ICG molar concentration (100, 80, 60, 40, 20, 10μM), excitation light spectrum (740, 760, 785nm) and angle of view (0~80°). We observed that ICG ring emitted fluorescence at longer wavelength than in blood and aqueous state. Observation angle between 0 and 50 provided similar brightness of images, while others are significantly less luminous. Excitation light between 740~760nm ensured non-overlapping spectrums of excitation light and fluorescence emission. PMID:27280060

  15. Fluorescent property of indocyanine green (ICG) rubber ring using LED and laser light sources

    PubMed Central

    Hong, Nha Young; Kim, Hong Rae; Lee, Hyun Min; Sohn, Dae Kyung; Kim, Kwang Gi

    2016-01-01

    Fluorescent properties of ICG depends on solvent. Fluorescent characteristics of ICG rubber rings and optimized detection system condition were identified. The fluorescent rubber rings are produced by drying mixture of ICG solution and liquid rubber. LED and laser light sources were used to test differences between them. Other variables are ICG molar concentration (100, 80, 60, 40, 20, 10μM), excitation light spectrum (740, 760, 785nm) and angle of view (0~80°). We observed that ICG ring emitted fluorescence at longer wavelength than in blood and aqueous state. Observation angle between 0 and 50 provided similar brightness of images, while others are significantly less luminous. Excitation light between 740~760nm ensured non-overlapping spectrums of excitation light and fluorescence emission. PMID:27280060

  16. AIRS-Light instrument concept and critical technology development

    NASA Astrophysics Data System (ADS)

    Maschhoff, Kevin R.

    2002-12-01

    Understanding Earth's climate, atmospheric transport mechanisms, and the hydrologic cycle requires a precise knowledge of global atmospheric circulation, temperature profiles, and water vapor distribution. The accuracy of advanced sounders such as AIRS/AMSU/HSB on NASA's Aqua spacecraft can match radiosonde accuracy. It is essential to fold those capabilities fully into the NPOESS, enabling soundings of radiosonde accuracy every 6 hours around the globe on an operational basis. However, the size, mass, power demands, and thermal characteristics of the Aqua sounding instrument suite cannot be accommodated on the NPOESS spacecraft. AIRS-Light is an instrument concept, developed under the Instrument Incubator Program, which provides IR sounding performance identical to the AIRS instrument but uses advances in HgCdTe FPA technology and pulse tube cooler technology, as well as design changes, to dramatically reduce the size, mass, and power demand, allowing AIRS-Light to meet all NPOESS spacecraft interface requirements. The AIRS-Light Instrument Incubator program fostered the development of photovoltaic-mode HgCdTe detector array technology for the 13.5-15.4 μm band covered by photoconductive-mode HgCdTe arrays in AIRS, achieved state of the art results in this band, and substantially reduced the development risk for this last new technology needed for AIRS-Light implementation.

  17. Ultraviolet light output of compact fluorescent lamps: comparison to conventional incandescent and halogen residential lighting sources.

    PubMed

    Nuzum-Keim, A D; Sontheimer, R D

    2009-05-01

    Patients with photosensitive dermatologic and systemic diseases often question the ultraviolet light (UVL) output of household lighting sources. Such individuals have increasing concern about potential UVL exposure from energy-efficient compact fluorescent lamps (CFL), as little data have been presented concerning their UVL output. The objective was to compare, via pilot study, the levels of ultraviolet A (UVA) and ultraviolet B (UVB) leak between residential lighting sources. Equivalent wattage CFL, incandescent and halogen bulbs were purchased from local retailers in Oklahoma City, Oklahoma, USA. The UVA and UVB outputs of these sources were measured under controlled conditions at 10, 25, 50, 100 and 150 cm away from the light source using an IL-1700 research radiometer equipped with UVA and UVB detectors. Negligible UVB and UVA was detected at 100 and 150 cm. Therefore, data were analysed from measurements at 10, 25 and 50 cm only. The results demonstrated UVA leak highest from incandescent and halogen bulbs, and UVB leak highest from CFL. The overall UVA/UVB leak was lowest from CFL shielded during the manufacturing process. In conclusion, patients with photosensitivity have choices depending on their relative risk from different UVL wavelength spectra. UVB exposure risk may be reduced the greatest by utilising CFL with manufacturer-provided shields. PMID:19395458

  18. Deeper Insight into Fluorescence-Excitation of Molecules by Light

    ERIC Educational Resources Information Center

    Wahab, M. Farooq; Gore, Gordon R.

    2013-01-01

    In a recent issue of "TPT," Gordon Gore made interesting observations about the red or yellow fluorescence when laser beams are passed through olive oil. With the excellent visuals contained in that article, we present a pictorial explanation of the questions that were raised in Ref 1 ("Fun with Fluorescence in Olive Oil,"…

  19. Light-induced fluorescence endoscopy (LIFE) imaging system for early cancer detection

    NASA Astrophysics Data System (ADS)

    Zeng, Haishan; MacAulay, Calum E.; Lam, Stephen; Palcic, Branko

    1999-09-01

    This paper summarizes our experiences on the development of a Light Induced Fluorescence Endoscopy (LIFE) imaging system for early cancer detection in the respiratory and gastrointestinal tract. The system utilizes tissue autofluorescence to provide real time video imaging of the examined organ. No exogenous fluorescent tumor markers are needed. It is used by a physician in adjunct to conventional white-light endoscopy. Suspicious areas are identified in pseudo color to guide biopsy. A multi- center clinical trial has demonstrated that in the lung, the relative sensitivity of white-light imaging + LIFE imaging vs. white-light imaging alone was 6.3 for intraepithelial neoplastic lesion detection and 2.71 when invasive carcinomas were also included. The following issues will be discussed: (1) spectroscopy study design for imaging system development; (2) architecture of the imaging systems; (3) different imaging modalities (white-light imaging, dual channel fluorescence imaging, and combined fluorescence/reflectance imaging); and (4) clinical applications.

  20. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching

    PubMed Central

    Wientjes, Emilie; Renger, Jan; Curto, Alberto G.; Cogdell, Richard; van Hulst, Niek F.

    2014-01-01

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~\

  1. White light-informed optical properties improve ultrasound-guided fluorescence tomography of photoactive protoporphyrin IX

    NASA Astrophysics Data System (ADS)

    Flynn, Brendan P.; DSouza, Alisha V.; Kanick, Stephen C.; Davis, Scott C.; Pogue, Brian W.

    2013-04-01

    Subsurface fluorescence imaging is desirable for medical applications, including protoporphyrin-IX (PpIX)-based skin tumor diagnosis, surgical guidance, and dosimetry in photodynamic therapy. While tissue optical properties and heterogeneities make true subsurface fluorescence mapping an ill-posed problem, ultrasound-guided fluorescence-tomography (USFT) provides regional fluorescence mapping. Here USFT is implemented with spectroscopic decoupling of fluorescence signals (auto-fluorescence, PpIX, photoproducts), and white light spectroscopy-determined bulk optical properties. Segmented US images provide a priori spatial information for fluorescence reconstruction using region-based, diffuse FT. The method was tested in simulations, tissue homogeneous and inclusion phantoms, and an injected-inclusion animal model. Reconstructed fluorescence yield was linear with PpIX concentration, including the lowest concentration used, 0.025 μg/ml. White light spectroscopy informed optical properties, which improved fluorescence reconstruction accuracy compared to the use of fixed, literature-based optical properties, reduced reconstruction error and reconstructed fluorescence standard deviation by factors of 8.9 and 2.0, respectively. Recovered contrast-to-background error was 25% and 74% for inclusion phantoms without and with a 2-mm skin-like layer, respectively. Preliminary mouse-model imaging demonstrated system feasibility for subsurface fluorescence measurement in vivo. These data suggest that this implementation of USFT is capable of regional PpIX mapping in human skin tumors during photodynamic therapy, to be used in dosimetric evaluations.

  2. AIRS-Light Instrument Concept and Critical Technology Development

    NASA Technical Reports Server (NTRS)

    Maschhoff, Kevin

    2001-01-01

    Understanding Earth's climate, atmospheric transport mechanisms, and the hydrologic cycle requires a precise knowledge of global atmospheric circulation, temperature profiles, and water vapor distribution. The accuracy of advanced sounders such as AIRS/AMSU/HSB on NASA's Aqua spacecraft can match radiosonde accuracy. It is essential to fold those capabilities fully into the NPOESS, enabling soundings of radiosonde accuracy, every 6 hours around the globe on an operational basis. However, the size, mass, power demands, and thermal characteristics of the Aqua sounding instrument suite cannot be accommodated on the NPOESS spacecraft. AIRS-Light is an instrument concept, developed under the Instrument Incubator Program, which provides IR sounding performance identical to the AIRS instrument, but uses advances in HgCdTe FPA technology and pulse tube cooler technology, as well as design changes to dramatically reduce the size, mass, and power demand, allowing AIRS-Light to meet all NPOESS spacecraft interface requirements. The instrument concept includes substantial re-use of AIRS component designs, including the complex AIRS FPA, to reduce development risk and cost. The AIRS-Light Instrument Incubator program fostered the development of photovoltaic-mode HgCdTe detector array technology for the 13.5-15.4 micron band covered by photoconductive-mode HgCdTe arrays in AIRS, achieved state of the art results in this band, and substantially reduced the development risk for this last new technology needed for AIRS-Light implementation, A demonstration of a prototype 14.5-15.4 micron band IRFPA in a reduced heat-load dewar together with the IMAS pulse tube cryocooler is in progress.

  3. Fluorescence properties of light-sensitive chromones used in archival polymer recording media

    NASA Astrophysics Data System (ADS)

    Martynov, I. Yu.; Barachevsky, V. A.; Ayt, A. O.; Kobeleva, O. I.; Valova, T. M.; Levchenko, K. S.; Yarovenko, V. N.; Krayushkin, M. M.

    2014-11-01

    The fluorescence properties of compounds formed upon irreversible photochemical transformation of some chromone derivatives in toluene were studied. At the first time, the quantum yields of the photoproducts were measured. The relationship between the fluorescence properties and the structure of these photoproducts was elucidated. It was shown that the properties of some chromones make them suitable for the design of light-sensitive recording media for optical discs with non-destructive fluorescence readout of optical information.

  4. Fixation-resistant photoactivatable fluorescent proteins for correlative light and electron microscopy

    PubMed Central

    Paez Segala, Maria G.; Sun, Mei G.; Shtengel, Gleb; Viswanathan, Sarada; Baird, Michelle A.; Macklin, John J.; Patel, Ronak; Allen, John R.; Howe, Elizabeth S.; Piszczek, Grzegorz; Hess, Harald F.; Davidson, Michael W.; Wang, Yalin; Looger, Loren L.

    2014-01-01

    Fluorescent proteins facilitate a variety of imaging paradigms in live and fixed samples. However, they cease to function following heavy fixation, hindering advanced applications such as correlative light and electron microscopy. Here we report engineered variants of the photoconvertible Eos fluorescent protein that function normally in heavily fixed (0.5–1% OsO4), plastic resin-embedded samples, enabling correlative super-resolution fluorescence imaging and high-quality electron microscopy. PMID:25581799

  5. Highly Efficient, Simplified, Solution-Processed Thermally Activated Delayed-Fluorescence Organic Light-Emitting Diodes.

    PubMed

    Kim, Young-Hoon; Wolf, Christoph; Cho, Himchan; Jeong, Su-Hun; Lee, Tae-Woo

    2016-01-27

    Highly efficient, simplified, solution-processed thermally activated delayed-fluorescence organic light-emitting diodes can be realized by using pure-organic thermally activated delayed fluorescence emitters and a multifunctional buffer hole-injection layer, in which high EQE (≈24%) and current efficiency (≈73 cd A(-1) ) are demonstrated. High-efficiency fluorescence red-emitting and blue-emitting devices can also be fabricated in this manner. PMID:26619309

  6. Organic Light Emitting Device as a fluorescence spectroscopy's light source : one step towards the lab-on-a-chip device

    NASA Astrophysics Data System (ADS)

    Camou, S.; Kitamura, M.; Gouy, Jean-Philippe; Fujita, Hiroyuki; Arakawa, Yasuhiko; Fujii, Teruo

    2003-02-01

    Many papers were recently dedicated to the lab-on-a-chip applications, where all the basic elements should be integrated directly onto the microchip. The fluorescence spectroscopy is mostly used as a detection method due to its high reliability and sensitivity, but requires light source and photo-detector. For the first time, we then propose to use Organic material Light Emitting Diode (OLED) to supply a light source for the optical detection based on fluorescence spectroscopy. By combining this OLED with micro-fluidic channels patterned in PDMS layer, the integration of light source on the chip is then achieved. First, the ability of Organic Material to excite fluorescent response from dye is demonstrated. Then, some configurations are described in order to decrease the major drawbacks that have to be solved before applying such kind of devices.

  7. Measurements of fluorescence yield of electrons in air under atmospheric conditions: A key parameter for energy of cosmic rays

    NASA Astrophysics Data System (ADS)

    Monnier Ragaigne, D.; Gorodetzky, P.; Blacksley, C.; Wicek, F.; Monard, H.; Dagoret-Campagne, S.

    2012-12-01

    The measurement of the fluorescence yield and its dependence on atmospheric properties such as pressure, temperature or pollutants, are essential to obtain a reliable measurement of the primary energy of cosmic rays. A new type of absolute measurement of the nitrogen fluorescence yield in the air will be performed at LAL using 3 items which will yield an unprecedented precision in all conditions of pressure, temperature, and pollutants. A 5 MeV electron beam will be provided by the new electron accelerator PHIL at LAL(Laboratoire de l'Accélérateur Linéaire, Univ Paris-Sud, CNRS/IN2P3, Orsay). This source will induce florescence yield inside an integrating sphere. The sphere will be surrounded by a spherical envelope to create a temperature controlled chamber (a Dewar). With this setup it will be possible to vary the temperature from -60 C to +40 C and the pressure from 1 to 0.01 atm. An output device on this sphere will be equipped with a set of optical fibers driving the fluorescence light to a Jobin-Yvon spectrometer equipped with an LN_{2} cooled CCD. The fluorescence spectrum in the 300-430 nm range will be accurately measured in steps of 0.1 nm resolution. A PMT equipped with a BG3 filter (the same as on JEM-EUSO) will be set on the sphere to measure the integrated yield. The expected precision of the yield should be better than 5%.

  8. Cancer detection using NIR elastic light scattering and tissue fluorescence imaging

    SciTech Connect

    Demos, S G; Staggs, M; Radousky, H B; Gandour-Edwards, R; deVere White, R

    2000-12-04

    Near infrared imaging using elastic light scattering and tissue fluorescence under long-wavelength laser excitation are explored for cancer detection. Various types of normal and malignant human tissue samples were utilized in this investigation.

  9. Energy Conservation Using Scotopically Enhanced Fluorescent Lighting In An Office Environment

    SciTech Connect

    2004-03-01

    This study was conducted in a recently built and occupied office building to determine whether the energy savings benefits of scotopically enhanced fluorescent lighting can be achieved while maintaining user acceptability.

  10. Evaluation of dental enamel caries assessment using Quantitative Light Induced Fluorescence and Optical Coherence Tomography.

    PubMed

    Maia, Ana Marly Araújo; de Freitas, Anderson Zanardi; de L Campello, Sergio; Gomes, Anderson Stevens Leônidas; Karlsson, Lena

    2016-06-01

    An in vitro study of morphological alterations between sound dental structure and artificially induced white spot lesions in human teeth, was performed through the loss of fluorescence by Quantitative Light-Induced Fluorescence (QLF) and the alterations of the light attenuation coefficient by Optical Coherence Tomography (OCT). To analyze the OCT images using a commercially available system, a special algorithm was applied, whereas the QLF images were analyzed using the software available in the commercial system employed. When analyzing the sound region against white spot lesions region by QLF, a reduction in the fluorescence intensity was observed, whilst an increase of light attenuation by the OCT system occurred. Comparison of the percentage of alteration between optical properties of sound and artificial enamel caries regions showed that OCT processed images through the attenuation of light enhanced the tooth optical alterations more than fluorescence detected by QLF System. QLF versus OCT imaging of enamel caries: a photonics assessment. PMID:26351155

  11. Measurement of Pressure Dependent Fluorescence Yield of Air: Calibration Factor for UHECR Detectors

    SciTech Connect

    Belz, J.W.; Burt, G.W.; Cao, Z.; Chang, F.Y.; Chen, C.C.; Chen, C.W.; Chen, P.; Field, C.; Findlay, J.; Huntemeyer, Petra; Huang, M.A.; Hwang, W.-Y.P.; Iverson, R.; Jones, B.F.; Jui, C.C.H.; Kirn, M.; Lin, G.-L.; Loh, E.C.; Maestas, M.M.; Manago, N.; Martens, K.; /Montana U. /Utah U. /Taiwan, Natl. Taiwan U. /SLAC /Rutgers U., Piscataway

    2005-07-06

    In a test experiment at the Final Focus Test Beam of the Stanford Linear Accelerator Center, the fluorescence yield of 28.5 GeV electrons in air and nitrogen was measured. The measured photon yields between 300 and 400 nm at 1 atm and 29 C are Y(760 Torr){sup air} = 4.42 {+-} 0.73 and Y(760 Torr){sup N{sub 2}} = 29.2 {+-} 4.8 photons per electron per meter. Assuming that the fluorescence yield is proportional to the energy deposition of a charged particle traveling through air, good agreement with measurements at lower particle energies is observed.

  12. Organic light-emitting device with a phosphor-sensitized fluorescent emission layer

    DOEpatents

    Forrest, Stephen; Kanno, Hiroshi

    2009-08-25

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters. The emissive region of the devices of the present invention comprise at least one phosphor-sensitized layer which has a combined emission from a phosphorescent emitter and a fluorescent emitter. In preferred embodiments, the invention relates to white-emitting OLEDS (WOLEDs).

  13. Regulation of red fluorescent light emission in a cryptic marine fish

    PubMed Central

    2014-01-01

    Introduction Animal colouration is a trade-off between being seen by intended, intra- or inter-specific receivers while not being seen by the unintended. Many fishes solve this problem by adaptive colouration. Here, we investigate whether this also holds for fluorescent pigments. In those aquatic environments in which the ambient light is dominated by bluish light, red fluorescence can generate high-contrast signals. The marine, cryptic fish Tripterygion delaisi inhabits such environments and has a bright red-fluorescent iris that can be rapidly up- and down-regulated. Here, we described the physiological and cellular mechanism of this phenomenon using a neurostimulation treatment with KCl and histology. Results KCl-treatment revealed that eye fluorescence regulation is achieved through dispersal and aggregation of black-pigmented melanosomes within melanophores. Histology showed that globular, fluorescent iridophores on the anterior side of the iris are grouped and each group is encased by finger-like extensions of a single posterior melanophore. Together they form a so-called chromatophore unit. By dispersal and aggregation of melanosomes into and out of the peripheral membranous extensions of the melanophore, the fluorescent iridophores are covered or revealed on the anterior (outside) of the iris. Conclusion T. delaisi possesses a well-developed mechanism to control the fluorescent emission from its eyes, which may be advantageous given its cryptic lifestyle. This is the first time chromatophore units are found to control fluorescent emission in marine teleost fishes. We expect other fluorescent fish species to use similar mechanisms in the iris or elsewhere in the body. In contrast to a previously described mechanism based on dendritic fluorescent chromatophores, chromatophore units control fluorescent emission through the cooperation between two chromatophore types: an emitting and an occluding type. The discovery of a second mechanism for fluorescence

  14. Far wing depolarization of light - Generalized absorption profiles. [in laser fluorescence spectroscopy of Sr vapor

    NASA Technical Reports Server (NTRS)

    Thomann, P.; Burnett, K.; Cooper, J.

    1981-01-01

    An absorption (and/or emission) event which takes place during a strong collision is called a 'correlated event'. It is discussed how correlated events affect the far red wing depolarization of fluorescence. Attention is given to an atomic vapor which is irradiated by linearly polarized light of a frequency on the red side of the resonance line. Two limiting cases are considered, corresponding to excitation in the impact region and in the quasi-static wing. In the quasi-static wing, absorption of a photon followed by fluorescence (rather than Rayleigh scattering), occurs mostly during a collision. Correlated events dominate the scattering process. Expressions derived for the polarization of the fluorescent light are applied to far red wing depolarization. It is found that the polarization of the fluorescent light does not go to zero in the far wing, but depends crucially on the detailed nature of the anisotropy in the long-range part of the interatomic potential.

  15. Implantable biosensors: analysis of fluorescent light propagation through skin

    NASA Astrophysics Data System (ADS)

    O'Neal, D. P.; McShane, Michael J.; Pishko, Michael V.; Cote, Gerard L.

    2001-06-01

    Progress towards a painless and hygienic glucose monitoring procedure for diabetics continues as the growth of diabetes mellitus reaches epidemic proportions in the American population. Utilizing an implantable fluorescence based glucose assay, the minimally invasive approach presented here has previously shown promise towards this goal in terms of glucose specificity and quantification for in vitro environments. However, in realistic physiological circumstances the depth of the implant can vary and optical properties of skin can change due to normal physiological conditions. Additionally, naturally occurring auto-fluorescence can obscure the sensor signal. An important concern under these conditions is that variations of fluorescent intensity due to these or other causes might be mistaken for glucose concentration fluctuations. New data shows that fluorescence-based glucose assays can be probed and interpreted in terms of glucose concentrations through pig skin at depths of up to 700 mm when immobilized in a bio-compatible polymer. When a combination of two fluorophores are employed as demonstrated here, reasonable changes in skin thickness and the confounding effects of the variations inherent in skin can be overcome for this glucose sensing application.

  16. Deeper Insight into Fluorescence--Excitation of Molecules by Light

    NASA Astrophysics Data System (ADS)

    Wahab, M. Farooq; Gore, Gordon R.

    2013-05-01

    In a recent issue of TPT, Gordon Gore made interesting observations about the red or yellow fluorescence when laser beams are passed through olive oil. With the excellent visuals contained in that article, we present a pictorial explanation of the questions that were raised in Ref 1.

  17. Numerical optix: A time-domain simulator of fluorescent light diffusion in turbid medium

    NASA Astrophysics Data System (ADS)

    Ma, Guobin; Delorme, Jean-François; Guilman, Olga; Leblond, Frédéric; Khayat, Mario

    2007-02-01

    The interest in fluorescence imaging has increased steadily in the last decade. Using fluorescence techniques, it is feasible to visualize and quantify the function of genes and the expression of enzymes and proteins deep inside tissues. When applied to small animal research, optical imaging based on fluorescent marker probes can provide valuable information on the specificity and efficacy of drugs at reduced cost and with greater efficiency. Meanwhile, fluorescence techniques represent an important class of optical methods being applied to in vitro and in vivo biomedical diagnostics, towards noninvasive clinical applications, such as detecting and monitoring specific pathological and physiological processes. ART has developed a time domain in vivo small animal fluorescence imaging system, eXplore Optix. Using the measured time-resolved fluorescence signal, fluorophore location and concentration can be quickly estimated. Furthermore, the 3D distribution of fluorophore can be obtained by fluorescent diffusion tomography. To accurately analyze and interpret the measured fluorescent signals from tissue, complex theoretical models and algorithms are employed. We present here a numerical simulator of eXplore Optix. It generates virtual data under well-controlled conditions that enable us to test, verify, and improve our models and algorithms piecewise separately. The theoretical frame of the simulator is an analytical solution of the fluorescence diffusion equation. Compared to existing models, the coupling of fluorophores with finite volume size is taken into consideration. Also, the influences of fluorescent inclusions to excitation and emission light are both accounted for. The output results are compared to Monte-Carlo simulations.

  18. Patterns and properties of polarized light in air and water

    PubMed Central

    Cronin, Thomas W.; Marshall, Justin

    2011-01-01

    Natural sources of light are at best weakly polarized, but polarization of light is common in natural scenes in the atmosphere, on the surface of the Earth, and underwater. We review the current state of knowledge concerning how polarization and polarization patterns are formed in nature, emphasizing linearly polarized light. Scattering of sunlight or moonlight in the sky often forms a strongly polarized, stable and predictable pattern used by many animals for orientation and navigation throughout the day, at twilight, and on moonlit nights. By contrast, polarization of light in water, while visible in most directions of view, is generally much weaker. In air, the surfaces of natural objects often reflect partially polarized light, but such reflections are rarer underwater, and multiple-path scattering degrades such polarization within metres. Because polarization in both air and water is produced by scattering, visibility through such media can be enhanced using straightforward polarization-based methods of image recovery, and some living visual systems may use similar methods to improve vision in haze or underwater. Although circularly polarized light is rare in nature, it is produced by the surfaces of some animals, where it may be used in specialized systems of communication. PMID:21282165

  19. Angular distribution of light emission from compound-eye cornea with conformal fluorescent coating

    NASA Astrophysics Data System (ADS)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2014-09-01

    The complex morphology of the apposition compound eyes of insects of many species provides them a wide angular field of view. This characteristic makes these eyes attractive for bioreplication as artificial sources of light. The cornea of a blowfly eye was conformally coated with a fluorescent thin film with the aim of achieving wide field-of-view emission. On illumination by shortwave-ultraviolet light, the conformally coated eye emitted visible light whose intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  20. Visible-Light Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian A.; Richards, Jeffrey T.

    2014-01-01

    Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure.

  1. Fluorescence in air excited by electrons from a 90Sr source

    NASA Astrophysics Data System (ADS)

    Sakaki, N.; Watanabe, Y.; Nagano, M.; Kobayakawa, K.

    2008-11-01

    The air fluorescence technique is used to observe ultra-high energy cosmic rays (UHECRs). In this technique, fluorescence from air excited by electrons within an extensive air shower (EAS) under various pressure and temperature conditions is detected by a telescope. The primary energy of the UHECR is estimated from the amount of fluorescence. Since ground-based experiments, such as Fly's Eye, HiRes, Auger, Telescope Array, are carried out at high altitudes, the effects of water vapor may be negligible and the photon yields in dry air, which we have measured and reported so far, will be applicable. However, in case of space-based experiments such as JEM-EUSO, most events will be observed above the sea. Photon yields in moist air are measured with a 90Sr β source and compared to those in dry air at wavelengths of 337, 358 and 391 nm. The presence of water vapor considerably reduces the photon yield. The decrease in the photon yield in moist air should be taken into account to interpret the longitudinal development of EASs near the sea surface, although the effects around the shower maximum for most showers might be small.

  2. A Combined Light Sheet Fluorescence and Differential Interference Contrast Microscope for Live Imaging of Multicellular Specimens

    NASA Astrophysics Data System (ADS)

    Baker, Ryan; Taormina, Michael; Jemielita, Matthew; Parthasarathy, Raghuveer

    2015-03-01

    We present a microscope capable of both light sheet fluorescence microscopy (LSFM) and differential interference contrast microscopy (DICM). The two imaging modes, which to the best of our knowledge have not previously been combined, are complementary: LSFM provides high speed three-dimensional imaging of fluorescently labeled components of multicellular systems, large fields of view, and low phototoxicity, while DICM reveals the unlabeled neighborhood of tissues, organs, and other structures with high contrast and inherent optical sectioning. Use of a shared detection path for both imaging modes enables simple integration of the two techniques in one microscope. To demonstrate the instrument's utility, we provide several examples which focus on the digestive tract of the larval zebrafish. We show that DICM can sometimes circumvent the need for fluorescent based techniques, augmenting the number of parameters obtainable per experiment when used alongside LSFM, and that DICM can be used to augment each experiment by imaging complementary features, such as non-fluorescent local environments near fluorescent samples (e.g. fluorescent enteric neurons imaged alongside the non-fluorescent gut wall), interactions between fluorescent and non-fluorescent samples (e.g. bacteria), and more. NSF Award 0922951, NIH Award 1P50 GM098911

  3. Amateur scientists - producing light from a bubble of air

    SciTech Connect

    Hiller, R.A.; Barber, B.P.

    1995-02-01

    A glowing bubble of air cannot be bought anywhere at any price. But with an oscilloscope, a moderately precise sound generator, a home stereo amplifier and about $100, readers can turn sound into light through a process called sonoluminescence. The apparatus is relatively simple. A glass spherical flask filled with water serves as the resonator - the cavity in which sound is created to trap and drive the bubble. Small speakers, called piezoelectric transducers, are cemented to the flask and powered by an audo generator and amplifier. Bubbles introduced into the water coalesce at the center of the flask and produce a dim light visible to the unaided eye in a darkened room.

  4. Detection of Biomass in New York City Aerosols: Light Scattering and Optical Fluorescence Techniques

    NASA Astrophysics Data System (ADS)

    Niebauer, M.; Alimova, A.; Katz, A.; Xu, M.; Rudolph, E.; Steiner, J.; Alfano, R. R.

    2005-12-01

    Optical spectroscopy is an ideal method for detecting bacteria and spores in real time. Optical fluorescence spectroscopy examination of New York City aerosols is used to quantify the mass of bacteria spores present in air masses collected at 14 liters/minute onto silica fiber filters, and on silica fiber ribbons using an Environmental Beta Attenuation Monitor manufactured by MetOne Instruments configured for the PM2.5 fraction. Dipicolinic acid (DPA), a molecule found primarily in bacterial spores, is the most characteristic component of spores in trial experiments on over 200 collected aerosol samples. DPA is extracted from the spores using a heat bath and chelated with Terbium. The DPA:Tb is detected by measuring its characteristic fluorescence with emission bands at 490, 545 and 585 nm for 270 nm excitation. Light scattering also measures the size distribution for a number of a variety of bacteria - Bacillus subtilis (rod shaped), Staphylococcus aureus (spherical) and Pseudomonas aeruginosa (short rods) establishing that optical techniques satisfactorily distinguish populations based on their variable morphology. Size and morphology are obtained by applying a variation of the Gaussian Ray Approximation theory of anomalous diffraction theory to an analysis of the transmission spectra in the range of 0.4 to 1.0 microns. In test experiments, the refractive index of the inner spore core of Bacillus subtilis decreases from 1.51 to 1.39 while the spore radius enlarges from 0.38 to 0.6 micrometers. Optical determinations are verified by oil-immersion techniques and by scanning electron microscope measurements. Characterization of spores, germinating spore materials, and bacteria is considered vital to tracing bacteria in the environment, for the development of life-detection systems for planetary exploration, monitoring pathogens in environmental systems, and for the preparation of anti-terrorism strategies.

  5. Manipulation of cellular light from green fluorescent protein by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    He, Hao; Li, Shiyang; Wang, Shaoyang; Hu, Minglie; Cao, Youjia; Wang, Chingyue

    2012-10-01

    Green fluorescent protein (GFP) is one of the most widely studied and exploited proteins in biochemistry and cell biology. It emits fluorescence following optical excitation, which is usually provided by a laser. Here, we report that fluorescence from enhanced GFP can be `turned off' by exposing cells to laser light. A short flash of femtosecond laser light is shown to deplete calcium in the endoplasmic reticulum of cells. Calcium-release-activated calcium channels are then activated by stromal interaction molecule 1 (STIM1). The rise in intracellular Ca2+ depolarizes mitochondria and increases the leakage of reactive oxygen species, which then permanently bleach the GFP. This controllable optical scheme for reactive oxygen species generation can also be used to modulate the photoconversion of GFP fluorescence from green to red emission and provide a mechanism for influencing cellular molecular dynamics.

  6. Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots.

    PubMed

    Meinert, Tobias; Tietz, Olaf; Palme, Klaus J; Rohrbach, Alexander

    2016-01-01

    Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

  7. Fluorescent Brighteners as Visible LED-Light Sensitive Photoinitiators for Free Radical Photopolymerizations.

    PubMed

    Zuo, Xiaoling; Morlet-Savary, Fabrice; Graff, Bernadette; Blanchard, Nicolas; Goddard, Jean-Philippe; Lalevée, Jacques

    2016-05-01

    The photochemical and electrochemical investigations of commercially available, safe, and cheap fluorescent brighteners, namely, triazinylstilbene (commercial name: fluorescent brightener 28) and 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, as well as their original use as photoinitiators of polymerization upon light emitting diode (LED) irradiation are reported. Remarkably, their excellent near-UV-visible absorption properties combined with outstanding fluorescent properties allow them to act as high-performance photoinitiators when used in combination with diaryliodonium salt. These two-component photoinitiating systems can be employed for free radical polymerizations of acrylate. In addition, this brightener-initiated photopolymerization is able to overcome oxygen inhibition even upon irradiation with low LED light intensity. The underlying photochemical mechanisms are investigated by electron-spin resonance-spin trapping, fluorescence, cyclic voltammetry, and steady-state photolysis techniques. PMID:27072016

  8. Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots

    PubMed Central

    Meinert, Tobias; Tietz, Olaf; Palme, Klaus J.; Rohrbach, Alexander

    2016-01-01

    Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

  9. Whole-body Fluorescent Optical Imaging Based on Power Light Emitting Diode.

    PubMed

    Chen, Yanping; Xiong, Tao; Yu, Li; Zeng, Shaoqun; Luo, Qingming

    2005-01-01

    With complex configuration, the general whole-body fluorescence optical imaging system is power-consuming for it is mainly composed of laser or mercury lamp, filter and fiber-optic cable. In this paper we aimed at setting up a compact imaging system based on power light emitting diode (LED). We first discussed fluorescence excitation efficiency of mercury lamp and LED. Then we developed a compact prototype whole-body fluorescence optical imaging system based on power LED. With the prototype, we monitored the dynamic course of green fluorescence protein (GFP) expressing tumors in the same intact nude mice. We also recorded the temporal behavior of the infectious process of GFP-expressing bacteria from outside intact infected animals. This study puts forward a platform for monitoring tumor growth. The experiment reveals that it is doable to substitute power LED for mercury lamp for whole-body fluorescence optical imaging. PMID:17282471

  10. Fluorescence enhancement of light-harvesting complex 2 from purple bacteria coupled to spherical gold nanoparticles

    SciTech Connect

    Bujak, Ł.; Czechowski, N.; Piatkowski, D.; Litvin, R.; Mackowski, S.; Brotosudarmo, T. H. P.; Pichler, S.; Cogdell, R. J.; Heiss, W.

    2011-10-24

    The influence of plasmon excitations in spherical gold nanoparticles on the optical properties of a light-harvesting complex 2 (LH2) from the purple bacteria Rhodopseudomonas palustris has been studied. Systematic analysis is facilitated by controlling the thickness of a silica layer between Au nanoparticles and LH2 complexes. Fluorescence of LH2 complexes features substantial increase when these complexes are separated by 12 nm from the gold nanoparticles. At shorter distances, non-radiative quenching leads to a decrease of fluorescence emission. The enhancement of fluorescence originates predominantly from an increase of absorption of pigments comprising the LH2 complex.

  11. Fluorescence enhancement of light-harvesting complex 2 from purple bacteria coupled to spherical gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Bujak, Ł.; Czechowski, N.; Piatkowski, D.; Litvin, R.; Mackowski, S.; Brotosudarmo, T. H. P.; Cogdell, R. J.; Pichler, S.; Heiss, W.

    2011-10-01

    The influence of plasmon excitations in spherical gold nanoparticles on the optical properties of a light-harvesting complex 2 (LH2) from the purple bacteria Rhodopseudomonas palustris has been studied. Systematic analysis is facilitated by controlling the thickness of a silica layer between Au nanoparticles and LH2 complexes. Fluorescence of LH2 complexes features substantial increase when these complexes are separated by 12 nm from the gold nanoparticles. At shorter distances, non-radiative quenching leads to a decrease of fluorescence emission. The enhancement of fluorescence originates predominantly from an increase of absorption of pigments comprising the LH2 complex.

  12. Up-converted fluorescence from photosynthetic light-harvesting complexes linearly dependent on excitation intensity.

    PubMed

    Leiger, Kristjan; Freiberg, Arvi

    2016-01-01

    Weak up-converted fluorescence related to bacteriochlorophyll a was recorded from various detergent-isolated and membrane-embedded light-harvesting pigment-protein complexes as well as from the functional membranes of photosynthetic purple bacteria under continuous-wave infrared laser excitation at 1064 nm, far outside the optically allowed singlet absorption bands of the chromophore. The fluorescence increases linearly with the excitation power, distinguishing it from the previously observed two-photon excited fluorescence upon femtosecond pulse excitation. Possible mechanisms of this excitation are discussed. PMID:25764015

  13. A compact multi-channel fluorescence sensor with ambient light suppression

    NASA Astrophysics Data System (ADS)

    Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

    2012-03-01

    A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

  14. Investigation of Relative Illuminance as a Function of Distance between Reflector and Fluorescent Light Source

    NASA Astrophysics Data System (ADS)

    Softic, Amela

    2007-04-01

    Although fluorescent lighting is considerably more efficient then incandescent, and is in wide use, manufacturers find new ways to improve its configuration and reduce energy use. Based on the fundamentals of ``Non-imaging Optics'', was experimentally investigated the dependence of illumination of a point in the space on the distance between the reflection and fluorescent light source. Monitoring of changes in illumination is performed by optical sensor and corresponding computer software. Investigation of the influence of the distance between the fluorescent light and the reflector on the relative illumination has shown, for the tested geometries, that by reducing the distance between them the illumination increased, even though the distance among the source and the measuring point got greater.

  15. Multicolor fluorescent light-emitting diodes based on cesium lead halide perovskite quantum dots

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Bai, Xue; Sun, Chun; Zhang, Xiaoyu; Zhang, Tieqiang; Zhang, Yu

    2016-08-01

    High quantum yield, narrow full width at half-maximum and tunable emission color of perovskite quantum dots (QDs) make this kind of material good prospects for light-emitting diodes (LEDs). However, the relatively poor stability under high temperature and air condition limits the device performance. To overcome this issue, the liquid-type packaging structure in combination with blue LED chip was employed to fabricate the fluorescent perovskite quantum dot-based LEDs. A variety of monochromatic LEDs with green, yellow, reddish-orange, and red emission were fabricated by utilizing the inorganic cesium lead halide perovskite quantum dots as the color-conversion layer, which exhibited the narrow full width at half-maximum (<35 nm), the relatively high luminous efficiency (reaching 75.5 lm/W), and the relatively high external quantum efficiency (14.6%), making it the best-performing perovskite LEDs so far. Compared to the solid state LED device, the liquid-type LED devices exhibited excellent color stability against the various working currents. Furthermore, we demonstrated the potential prospects of all-inorganic perovskite QDs for the liquid-type warm white LEDs.

  16. Light adaptation of the unicellular red alga, Cyanidioschyzon merolae, probed by time-resolved fluorescence spectroscopy.

    PubMed

    Ueno, Yoshifumi; Aikawa, Shimpei; Kondo, Akihiko; Akimoto, Seiji

    2015-08-01

    Photosynthetic organisms change the quantity and/or quality of their pigment-protein complexes and the interactions among these complexes in response to light conditions. In the present study, we analyzed light adaptation of the unicellular red alga Cyanidioschyzon merolae, whose pigment composition is similar to that of cyanobacteria because its phycobilisomes (PBS) lack phycoerythrin. C. merolae were grown under different light qualities, and their responses were measured by steady-state absorption, steady-state fluorescence, and picosecond time-resolved fluorescence spectroscopies. Cells were cultivated under four monochromatic light-emitting diodes (blue, green, yellow, and red), and changes in pigment composition and energy transfer were observed. Cells grown under blue and green light increased their relative phycocyanin levels compared with cells cultured under white light. Energy-transfer processes to photosystem I (PSI) were sensitive to yellow and red light. The contribution of direct energy transfer from PBS to PSI increased only under yellow light, while red light induced a reduction in energy transfer from photosystem II to PSI and an increase in energy transfer from light-harvesting chlorophyll protein complex I to PSI. Differences in pigment composition, growth, and energy transfer under different light qualities are discussed. PMID:25577254

  17. High efficiency and brightness fluorescent organic light emitting diode by triplet-triplet fusion

    SciTech Connect

    Forrest, Stephen; Zhang, Yifan

    2015-02-10

    A first device is provided. The first device further comprises an organic light emitting device. The organic light emitting device further comprises an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer may include an organic host compound and at least one organic emitting compound capable of fluorescent emission at room temperature. Various configurations are described for providing a range of current densities in which T-T fusion dominates over S-T annihilation, leading to very high efficiency fluorescent OLEDs.

  18. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn.

    PubMed

    Linkosalo, Tapio; Heikkinen, Juha; Pulkkinen, Pertti; Mäkipää, Raisa

    2014-01-01

    We studied the photosynthetic activity of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst) in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 1-3 times per week. We began by measuring shoots present in late winter (i.e., March 2013) before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only. We analyzed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence. The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 2013-2014 was unusually mild and similar to future conditions predicted by global climate models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration. PMID:24982664

  19. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn

    PubMed Central

    Linkosalo, Tapio; Heikkinen, Juha; Pulkkinen, Pertti; Mäkipää, Raisa

    2014-01-01

    We studied the photosynthetic activity of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst) in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 1–3 times per week. We began by measuring shoots present in late winter (i.e., March 2013) before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only. We analyzed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence. The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 2013–2014 was unusually mild and similar to future conditions predicted by global climate models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration. PMID:24982664

  20. Mechanistic Studies of the Genetically Encoded Fluorescent Protein Voltage Probe ArcLight

    PubMed Central

    Han, Zhou; Jin, Lei; Chen, Fuyi; Loturco, Joseph J.; Cohen, Lawrence B.; Bondar, Alexey; Lazar, Josef; Pieribone, Vincent A.

    2014-01-01

    ArcLight, a genetically encoded fluorescent protein voltage probe with a large ΔF/ΔV, is a fusion between the voltage sensing domain of the Ciona instestinalis voltage sensitive phosphatase and super ecliptic pHluorin carrying a single mutation (A227D in the fluorescent protein). Without this mutation the probe produces only a very small change in fluorescence in response to voltage deflections (∼1%). The large signal afforded by this mutation allows optical detection of action potentials and sub-threshold electrical events in single-trials in vitro and in vivo. However, it is unclear how this single mutation produces a probe with such a large modulation of its fluorescence output with changes in membrane potential. In this study, we identified which residues in super ecliptic pHluorin (vs eGFP) are critical for the ArcLight response, as a similarly constructed probe based on eGFP also exhibits large response amplitude if it carries these critical residues. We found that D147 is responsible for determining the pH sensitivity of the fluorescent protein used in these probes but by itself does not result in a voltage probe with a large signal. We also provide evidence that the voltage dependent signal of ArcLight is not simply sensing environmental pH changes. A two-photon polarization microscopy study showed that ArcLight's response to changes in membrane potential includes a reorientation of the super ecliptic pHluorin. We also explored different changes including modification of linker length, deletion of non-essential amino acids in the super ecliptic pHluorin, adding a farnesylation site, using tandem fluorescent proteins and other pH sensitive fluorescent proteins. PMID:25419571

  1. Biocidal activity of a light-absorbing fluorescent conjugated polyelectrolyte.

    PubMed

    Lu, Liangde; Rininsland, Frauke H; Wittenburg, Shannon K; Achyuthan, Komandoor E; McBranch, Duncan W; Whitten, David G

    2005-10-25

    Herein we describe studies that indicate a cationic conjugated polyelectrolyte shows biocidal activity against gram-negative bacteria (Escherichia coli, E. coli, BL21, with plasmids for Azurin and ampicillin resistance) and gram-positive bacterial spores (Bacillus anthracis, Sterne, B. anthracis, Sterne). These studies were carried out with aqueous suspensions of the conjugated polyelectrolyte, with the polyelectrolyte in supported formats and with samples in which the conjugated polyelectrolyte was coated on the bacteria. The results are interesting in that the biocidal activity is light-induced and appears effective due to the ability of the conjugated polyelectrolyte to form a surface coating on both types of bacteria. The effects observed here should be general and suggest that a range of conjugated polyelectrolytes in different formulations may provide a useful new class of biocides for both dark and light-activated applications. PMID:16229539

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Multicolor 4D Fluorescence Microscopy using Ultrathin Bessel Light Sheets

    PubMed Central

    Zhao, Teng; Lau, Sze Cheung; Wang, Ying; Su, Yumian; Wang, Hao; Cheng, Aifang; Herrup, Karl; Ip, Nancy Y.; Du, Shengwang; Loy, M. M. T.

    2016-01-01

    We demonstrate a simple and efficient method for producing ultrathin Bessel (‘non-diffracting’) light sheets of any color using a line-shaped beam and an annulus filter. With this robust and cost-effective technology, we obtained two-color, 3D images of biological samples with lateral/axial resolution of 250 nm/400 nm, and high-speed, 4D volume imaging of 20 μm sized live sample at 1 Hz temporal resolution. PMID:27189786

  4. Multicolor 4D Fluorescence Microscopy using Ultrathin Bessel Light Sheets.

    PubMed

    Zhao, Teng; Lau, Sze Cheung; Wang, Ying; Su, Yumian; Wang, Hao; Cheng, Aifang; Herrup, Karl; Ip, Nancy Y; Du, Shengwang; Loy, M M T

    2016-01-01

    We demonstrate a simple and efficient method for producing ultrathin Bessel ('non-diffracting') light sheets of any color using a line-shaped beam and an annulus filter. With this robust and cost-effective technology, we obtained two-color, 3D images of biological samples with lateral/axial resolution of 250 nm/400 nm, and high-speed, 4D volume imaging of 20 μm sized live sample at 1 Hz temporal resolution. PMID:27189786

  5. Development of a noninvasive diabetes screening device using the ratio of fluorescence to Rayleigh scattered light

    NASA Astrophysics Data System (ADS)

    Yu, Nai-Teng; Krantz, Brian S.; Eppstein, Jonathan A.; Ignotz, Keith D.; Samuels, Mark A.; Long, James R.; Price, John

    1996-07-01

    We have developed a new lens measurement system that simultaneously measures the intensities of fluorescence and Rayleigh components at various distances into the lens along the optical axis. The noninvasive measurement is performed through an undilated pupil, and with the assistance of a pupil tracking system that facilitates maintaining the x and y positions of the sample volume to within +/- 100 micrometers of any programmed 'lock' position. The intensity of the Rayleigh component that is used to normalize the measured fluorescent signal serves to correct the attenuation effects due to absorption and lens light scatter. This report, resulting from a SpectRx Site L clinical study using a refined instrumentation, presents analysis of fluorescence and Rayleigh data from the lenses of 923 controls and 239 diabetic subjects ranging from 23 to 75 years old. Fluorescence and Rayleigh data have been obtained via confocal mode from various locations nominally along the lens optical axis for controls and diabetics, at different ages, using three pairs of excitation and collection wavelengths: 364/495 nm, 434/495 nm, and 485/515 nm. For control subjects, there exists a strong, almost linear relationship between age and fluorescence, while diabetic subjects tend to deviate from this age-fluorescence relationship. Our data show that the lenses of diabetic patients are subject to an accelerated aging process, presumably due to an elevated level of brown and fluorescence protein adducts and crosslinks from nonenzymatic glycosylation. We have also shown that by using the measured Rayleigh profiles to normalize the measured fluorescence, most of the absorption effects are removed and therefore the separation between the fluorescence of diabetics and controls is greatly improved. Thus, the device for measuring fluorescence/Rayleigh ratios can be used to noninvasively screen populations for possible undiagnosed diabetes.

  6. A combined light sheet fluorescence and differential interference contrast microscope for live imaging of multicellular specimens.

    PubMed

    Baker, R P; Taormina, M J; Jemielita, M; Parthasarathy, R

    2015-05-01

    We describe a microscope capable of both light sheet fluorescence microscopy and differential interference contrast microscopy (DICM). The two imaging modes, which to the best of our knowledge have not previously been combined, are complementary: light sheet fluorescence microscopy provides three-dimensional imaging of fluorescently labelled components of multicellular systems with high speed, large fields of view, and low phototoxicity, whereas differential interference contrast microscopy reveals the unlabelled neighbourhood of tissues, organs, and other structures with high contrast and inherent optical sectioning. Use of a single Nomarski prism for differential interference contrast microscopy and a shared detection path for both imaging modes enables simple integration of the two techniques in one custom microscope. We provide several examples of the utility of the resulting instrument, focusing especially on the digestive tract of the larval zebrafish, revealing in this complex and heterogeneous environment anatomical features, the behaviour of commensal microbes, immune cell motions, and more. PMID:25611324

  7. The impact of algal fluorescence on the underwater polarized light field

    NASA Astrophysics Data System (ADS)

    Tonizzo, A.; Ibrahim, A.; Zhou, J.; Gilerson, A.; Gross, B.; Moshary, F.; Ahmed, S.

    2010-04-01

    Multiangular, hyperspectral measurements of the underwater polarization light field, as well as comprehensive measurements of IOPs were collected in several cruise campaigns in the Chesapeake/Virginia area and New York Harbor/Hudson River areas. The waters examined were mostly eutropic water with Chlorophyll a concentration up to approximately 57 μg/L. It is found that Chlorophyll a fluorescence markedly impacts (reduces) the underwater degree of polarization (DOP) in the 650 - 700 nm spectral region. By taking note of the unpolarized nature of algal fluorescence and the partially polarized properties of elastic scattering, particularly by non-algal particles, we were able to separate the Chlorophyll a fluorescence signal from the total radiance. The analysis is based on comparisons of the underwater multiangular, hyperspectral polarization measurements which include fluorescence, compared with adding - doubling polarized radiative transfer simulations of elastic scattering which use measured IOPs as input, and which do not include fluorescence. The difference between the two shows the impact of fluorescence. These relationships are examined in detail, and the efficacy of using DOP measurements for underwater fluorescence retrieval is evaluated for different scattering geometries and water conditions.

  8. Cutaneous melanin exhibiting fluorescence emission under near-infrared light excitation.

    PubMed

    Huang, Zhiwei; Zeng, Haishan; Hamzavi, Iltefat; Alajlan, Abdulmajeed; Tan, Eileen; McLean, David I; Lui, Harvey

    2006-01-01

    Under ultraviolet and visible light excitation, melanin is essentially a nonfluorescent substance. This work reports our study on near-infrared (NIR) fluorescence properties of melanins, and explores potential applications of NIR fluorescence techniques for evaluating skin disorders involving melanin. The NIR fluorescence spectrum is obtained using a fiber optic NIR spectrometer under 785-nm laser excitation. In vitro measurements are performed on synthetic dihydroxyphenylalanine (DOPA) melanin, melanin extracted from Sepia ink sacs, human hair, animal fur, and bird feathers. Paired spectral comparisons of white and black skin appendages show that melanization of hair, fur, or feathers more than doubles the NIR fluorescence. In vivo NIR autofluorescence of normal dorsal and volar forearm skin of 52 volunteers is measured. Dorsal forearm skin, which is darker than volar skin, exhibits significantly greater NIR fluorescence. Patients with vitiligo (n=4), compound nevus (n=3), nevus of Ota (n=1), superficial spreading melanoma (n=3), and postinflammatory hyperpigmentation (n=1) are also evaluated. NIR fluorescence is greater within the lesion than the surrounding normal skin for all these conditions except vitiligo, where the converse was true. The observed melanin NIR fluorescence provides a new approach to in vitro and in vivo melanin detection and quantification that may be particularly useful for evaluating pigmented skin lesions. PMID:16822060

  9. Fluorescent light irradiation and its mutagenic potential in cultured mammalian cells

    SciTech Connect

    Pant, K.; Thilager, A.

    1994-12-31

    The photobiological effect of light is characterized by its energy emission at different wave lengths. Therefore by studying the energy emission spectra at different light sources and their photobiological activities, one can relate wavelength range(s) of the spectrum to a particular photobiological effect. We studied the potential of light irradiation from standard fluorescent bulbs (Sylvania 34WT-12) used in offices and laboratories to induce unscheduled DNA Synthesis (UDS) and mutations in cultured mammalian cells. The energy emission spectrum of the bulbs was determined at every 10 nanometers from 300nM to 700nM. The Chinese hamster ovary (CHO) cells were used to study the induction of mutations at the Hypoxanthine Guanine Phosphoribosyl Transferase (HGPRT) locus. Primary rat hepatocyte cultures were used to study the effect of light irradiation on UDS. The CHO cells were cultured in tissue culture flasks in minimum light conditions (.02mw/cm{sup 2}) and exposed to light irradiations with durations from 0 to 40 minutes. The cultures were maintained in darkness during the expression period and evaluated for HGPRT mutant frequencies. Similarly, the primary rat hepatocyte cultures were cultured on cover slips under minimal light conditions except for light irradiation and evaluated for UDS using 3H-thymidine labelled auto-radiography. The results of the study indicate that irradiation from fluorescent lights caused a slight elevation in the HGPRT mutant frequency in CHO cells. However a significant increase in UDS was not observed even at the maximum light irradiation dose. These results were compared to data obtained from similar experiments conducted with fluorescent bulbs with different energy emission spectra.

  10. Light-Enhanced Fluorescence of Multi-Level Cavitands Possessing Pyridazine Upper rim.

    PubMed

    Janosi, Tibor Zoltan; Makkai, Geza; Kegl, Timea; Matyus, Peter; Kollar, Laszlo; Erostyak, Janos

    2016-03-01

    Completely different fluorescence behaviour of cavitands based on a same calix[4]resorcinarene compound was observed. While the fluorescence intensity of the parent compound, tetramethyl-cavitand (1) slowly faded as a result of UV-light exposure, the emission of the three-level cavitand with pyridazine moieties at the upper rim (5a) was enhanced by the excitation in the UV-region. The structure of fluorescence emission (characterized by excitation-emission matrices) and the absorption of 5a remained unaltered. The analysis of fluorescence decay curves reveals the presence of two separated components assigned to two individual emitting species. The measured significant increase of the average lifetime and quantum yield is the consequence of the UV-light induced transition between the different states of 5a. These observations can be explained by the structural difference between 5a and 1. As a counterpart of the naked cavitand (1) with methyl substituents at the upper rim only, 5a has three additional moieties benzene, triazole and pyridazine levels. Computational studies proved the existence of two conformational isomers of 5a. Upon ultraviolet light excitation a "dark" to "light" conformational transition occurs between the two isomers. This hypothesis was confirmed by anisotropy decay measurements. PMID:26715516

  11. [Derivative fluorescence probe recognition results of the light physical mechanism of metal ions].

    PubMed

    Dai, Yu-mei; Hu, Xiao-jun; Li, Fu-jun; Xie, Yu-meng; Zhao, Yang-yang; Zhou, Qiao

    2015-02-01

    As people deeply study the electronic spectra of fluorescent compounds and photophysical behavior, enormous progress has been made in the aspect of changes and states of different systems in the use of fluorescent molecules as probes. PTC-DA is a kind of typical fluorescent molecular probe that is highly sensitive and selective in water environment. This paper makes a research on the physical mechanism of light of PTCDA by TDF (Density Functional Theory), calculates the optimal configuration the charge population and excitation spectra of PTCDA molecules under ideal condition and acquires PTCDA fluorescence emission spectra then analyses that PTCDA is a kind of quenching and dual colorimetric signal probe response. Its optical signal response mechanism belongs to ICT (Intramolecular Charge Transfer) mechanism. According to the results, this perylene derivatives is fitted with Cu2+ excited state absorption spectra. Before and after the combination with Cu2+, the peak shape of absorption spectrum is similar. When copper is added, the overall absorption peak position occurred redshift, quenching discoloration happens. By comparing with experimental values, the calculated molecular configuration is reasonable and effective and the peak of excitation spectra is realistic. Analysis shows that: PTCDA molecules divalent copper ions have better fluorescence detection activity, the optical signal response mechanisms are intramolecular charge transfer (ICT) mechanisms. When a molecule receives divalent copper ions, the absorption spectrum peak position redshifts, intramolecular charge transfer direction and intensity changes. There occur both quenching signal and discoloration signal. It is a kind of fluorescent probe material with double quenching and discoloration fluorescent signal, which has great potential for development. This paper makes an early-stage exploration of the physical mechanism of light response mechanism analysis in molecular fluorescent probe field and

  12. White polymer light emitting diode using blend of fluorescent polymers

    NASA Astrophysics Data System (ADS)

    Prakash, Asit; Katiyar, Monica

    2012-10-01

    White polymer light emitting diodes (WPLEDs) are fabricated using poly(9,9-dioctylfluorene-2,7-diyl) (PFO) as host and poly [2-methoxy-5-(2'-ethyl-hexyloxy)]-1,4-phenylene vinylene (MEH-PPV) as guest material having structure ITO(150nm)/PEDOT:PSS(40nm)/PFO:MEH-PPV(75-90nm)/Ca(20nm)/Al(120nm). Photoluminescence spectra of blends with different MEH-PPV concentration reveal that at low doping level of MEH-PPV, blue emission from PFO and yellow emission from MEH-PPV co-exist due to incomplete energy transfer from PFO to MEH-PPV. Surface morphology of the spin coated blend films with different concentrations of MEH-PPV were studied using atomic force microscopy (AFM). It shows segregation/agglomeration of polymers at higher concentration of MEH-PPV (~2.0 wt %). Finally, WPLEDs, having MEH-PPV in the range of 0.8-2.0 wt%, were fabricated. We obtained best device at 0.8 wt% of MEH-PPV, it shows white light with Commission Internationale de l'Enclairage (CIE) coordinate of (0.30, 0.38). Electroluminescence turn-on voltage of the device was 4.0 V and maximum luminance reaches 1234 cd/m2 at 8.5 V. The luminous current and power efficiency at current density of 22 mA/cm2 were found to be 2.3 cd/A and 1.1 lm/W, respectively.

  13. Light transmission and air used for inspection of glovebox gloves.

    SciTech Connect

    Castro, J. M.; Steckle, W. P. , Jr.; Macdonald, J. M.

    2002-01-01

    Various materials used for manufacturing the glovebox gloves are translucent material such as hypalon, rubbers, and neoprene. This means that visible light can be transmitted through the inside of the material. Performing this test can help to increase visualization of the integrity of the glove. Certain flaws such as pockmarks, foreign material, pinholes, and scratches could be detected with increased accuracy. An analysis was conducted of the glovebox gloves obscure polymer material using a inspection light table. The fixture is equipped with a central light supply and small air pump to inflate the glove and test for leak and stability. A glove is affixed to the fixture for 360-degree inspection. Certain inspection processes can be performed: (1) Inspection for pockmarks and thin areas within the gloves; (2) Observation of foreign material within the polymer matrix; and (3) Measurements could be taken for gloves thickness using light measurements. This process could help reduce eyestrain when examining gloves and making a judgment call on the size of material thickness in some critical areas. Critical areas are fingertips and crotch of fingers.

  14. The Effects of Fluorescent and Incandescent Lighting on the Repetitive Behaviours of Autistic and Intellectually Handicapped Children.

    ERIC Educational Resources Information Center

    Fenton, D. M.; Penney, R.

    1985-01-01

    Repetitive behaviors of five autistic and five intellectually disabled children were observed under both fluorescent and incandescent lighting conditions. Findings supported the hypothesis that autistic children engage in a significantly greater frequency of stereotypes under fluorescent lighting, while there is no significant difference among…

  15. High-efficiency white organic light-emitting diodes based on a blue thermally activated delayed fluorescent emitter combined with green and red fluorescent emitters.

    PubMed

    Higuchi, Takahiro; Nakanotani, Hajime; Adachi, Chihaya

    2015-03-25

    A new device architecture for highly efficient white organic light-emitting diodes is proposed, using a molecule exhibiting blue thermally activated delayed fluorescence as a common source of singlet excitons for molecules emitting red and green light based on conventional fluorescence. The device, with an optimum combination of materials, shows a maximum external quantum efficiency of over 12% without using phosphorescent emitters. PMID:25664428

  16. Flexible fluorescent white organic light emitting diodes with ALD encapsulation

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Sheng; Chittawanij, Apisit; Juang, Fuh-Shyang; Lin, Pen-Chu; Hong, Lin-Ann; Tsai, Feng-Yu; Tseng, Ming-Hong; Wang, Ching-Chiun; Chen, Chien-Chih; Lin, Kung-Liang; Chen, Szu-Hao

    2015-08-01

    In this paper, the flexible white organic light-emitting diodes (WOLED) was fabricated on polyethylene naphthalate (PEN) with structure of ITO/EHI608 (75 nm)/HTG-1 (10 nm)/3% EB502:0.8% EY53 (5 nm)/3% EB502 (35 nm)/Alq3 (10 nm)/LiF (0.8 nm)/Al (150 nm) and was compared with glass substrate the same structure. It was seen that the performances of flexible and glass substrate are almost the same. The luminance, current efficiency, and CIE coordinates of flexible device is 6351 cd/m2, 12.7 cd/A, and (0.31, 0.38) at 50 mA/cm2, respectively. Then, an Al2O3/HfO2 film on polyethylene terephthalate (PET) was deposited using atomic layer deposition (ALD) as a thin film encapsulation layer have been described and compared, such as the characteristics of water permeability and lifetime of flexible WOLED. The results show that the PET/ALD film low value of about 0.04 g/m2d, and the PET film shows WVTR of about 3.8 g/m2/d. The lifetimes of PET/ALD and PET encapsulations are 840 min and 140 min, respectively. Simultaneous deposition of ALD film on PET film gave the lifetime of flexible WOLED is six times longer than device without ALD encapsulation.

  17. Influence of laser polarization on plasma fluorescence emission during the femtosecond filamentation in air

    NASA Astrophysics Data System (ADS)

    Shi, Yan; Chen, Anmin; Jiang, Yuanfei; Li, Suyu; Jin, Mingxing

    2016-05-01

    The laser polarization state has a great influence on the plasma fluorescence emission during femtoseond filamentation in air. For the spectral lines from N2, in the case of focusing lens with longer focal length (f=100 cm), due to the impact excitation, circular polarization leads to stronger fluorescence emission when the laser energy is higher than the 'energy threshold' (2.0 mJ). As a lens with shorter focal length (f=40 cm) is used, a similar phenomenon can be observed, however, the 'energy threshold' is much lower, which is lower than 0.8 mJ. For the lines from N2+, especially for the 391 nm one, their emission is stronger in the linear polarization state. The mechanism of plasma fluorescence emission during femtosecond filamentation is discussed based on the analysis of these phenomena, which will be helpful to the remote sensing and spectrum analysis.

  18. Fluorescence lifetime measurement via a radionuclide-scintillation light source and analog cross correlation.

    PubMed

    Burden, D L; Hobbs, S E; Hieftje, G M

    1997-05-15

    beta-Emitting 90Sr is used with a plastic scintillator to produce excitation-light pulses for fluorescence lifetime analysis. This light source is less expensive, more compact, and much more reliable than traditionally employed excitation sources such as lasers or pulsed flash lamps. The pulse train from this light source varies randomly in amplitude and time. Cross-correlation signal analysis is ideal for such a source because, unlike other time domain techniques, cross correlation takes complete advantage of its random nature. Here we report on the construction of an instrument and the methods employed to make fluorescence lifetime measurements via the new source and an analog correlation processor. Although the light intensity of the scintillator-based excitation source is comparatively low, an adequate signal level can be generated. The fluorescence lifetimes of three fluorophores are measured with a 1-mCi radionuclide to demonstrate a lifetime range from less than 1.5 to 28 ns. Long-lifetime measurements require an extra calibration step in order to compensate for delay cable energy loss. The light collection efficiency of the current instrument was found to be undesirably low; improvements in the instrument optics are suggested that will increase the collection efficiency and enhance the detection capability. PMID:9164162

  19. A compact fluorescence and white light imaging system for intraoperative visualization of nerves

    NASA Astrophysics Data System (ADS)

    Gray, Dan; Kim, Evgenia; Cotero, Victoria; Staudinger, Paul; Yazdanfar, Siavash; Tan Hehir, Cristina

    2012-03-01

    Fluorescence image guided surgery (FIGS) allows intraoperative visualization of critical structures, with applications spanning neurology, cardiology and oncology. An unmet clinical need is prevention of iatrogenic nerve damage, a major cause of post-surgical morbidity. Here we describe the advancement of FIGS imaging hardware, coupled with a custom nerve-labeling fluorophore (GE3082), to bring FIGS nerve imaging closer to clinical translation. The instrument is comprised of a 405nm laser and a white light LED source for excitation and illumination. A single 90 gram color CCD camera is coupled to a 10mm surgical laparoscope for image acquisition. Synchronization of the light source and camera allows for simultaneous visualization of reflected white light and fluorescence using only a single camera. The imaging hardware and contrast agent were evaluated in rats during in situ surgical procedures.

  20. Compact fluorescence and white-light imaging system for intraoperative visualization of nerves

    NASA Astrophysics Data System (ADS)

    Gray, Dan; Kim, Evgenia; Cotero, Victoria; Staudinger, Paul; Yazdanfar, Siavash; tan Hehir, Cristina

    2012-02-01

    Fluorescence image guided surgery (FIGS) allows intraoperative visualization of critical structures, with applications spanning neurology, cardiology and oncology. An unmet clinical need is prevention of iatrogenic nerve damage, a major cause of post-surgical morbidity. Here we describe the advancement of FIGS imaging hardware, coupled with a custom nerve-labeling fluorophore (GE3082), to bring FIGS nerve imaging closer to clinical translation. The instrument is comprised of a 405nm laser and a white light LED source for excitation and illumination. A single 90 gram color CCD camera is coupled to a 10mm surgical laparoscope for image acquisition. Synchronization of the light source and camera allows for simultaneous visualization of reflected white light and fluorescence using only a single camera. The imaging hardware and contrast agent were evaluated in rats during in situ surgical procedures.

  1. Development of image reconstruction algorithms for fluorescence diffuse optical tomography using total light approach

    NASA Astrophysics Data System (ADS)

    Okawa, S.; Yamamoto, H.; Miwa, Y.; Yamada, Y.

    2011-07-01

    Fluorescence diffuse optical tomography (FDOT) based on the total light approach is developed. The continuous wave light is used for excitation in this system. The reconstruction algorithm is based on the total light approach that reconstructs the absorption coefficients increased by the fluorophore. Additionally we propose noise reduction using the algebraic reconstruction technique (ART) incorporating the truncated singular value decomposition (TSVD). Numerical and phantom experiments show that the developed system successfully reconstructs the fluorophore concentration in the biological media, and the ART with TSVD alleviates the influence of noises. In vivo experiment demonstrated that the developed FDOT system localized the fluorescent agent which was concentrated in the cancer transplanted into a kidney in a mouse.

  2. Standoff Detection of Volatile Organic Compounds In Air Using Laser Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Clark, Jerry; Alexander, Alonzo; Wiggins, Delonia; Williams, Sydney; Akpovo, Charlemagne; Mezonlin, Ephrem; Johnson, Joseph, III; CenterPlasma Science; Technology (CePaST) Team

    2011-10-01

    The use of laser-induced fluorescence has proven to be an excellent method of detecting important intermediates in turbulent systems. However, Acetylene detection in air at ambient temperatures has proven more challenging. Molecular spectra were collected in laser induced acetylene plasmas using a 250 mJ Nd:YAG laser and an optical parametric oscillator (OPO) to achieve the 260 nm wavelength and greater than 3 mJ energy necessary to excite acetylene molecules. The acetylene laser-induced fluorescence excitation was observed at the 228 nm wavelength. Using various concentration ratios, acetylene was mixed with air to specifically determine the capabilities of standoff acetylene detection at atmospheric pressure. These results will lead to further research and development of turbulence based battlefield ready detection devices. Research supported in part by NSF grants to FAMU.

  3. Spontaneous Rayleigh-Brillouin scattering of ultraviolet light in nitrogen, dry air, and moist air.

    PubMed

    Witschas, Benjamin; Vieitez, Maria O; van Duijn, Eric-Jan; Reitebuch, Oliver; van de Water, Willem; Ubachs, Wim

    2010-08-01

    Atmospheric lidar techniques for the measurement of wind, temperature, and optical properties of aerosols rely on the exact knowledge of the spectral line shape of the scattered laser light on molecules. We report on spontaneous Rayleigh-Brillouin scattering measurements in the ultraviolet at a scattering angle of 90 degrees on N(2) and on dry and moist air. The measured line shapes are compared to the Tenti S6 model, which is shown to describe the scattering line shapes in air at atmospheric pressures with small but significant deviations. We demonstrate that the line profiles of N(2) and air under equal pressure and temperature conditions differ significantly, and that this difference can be described by the S6 model. Moreover, we show that even a high water vapor content in air up to a volume fraction of 3.6vol.% has no influence on the line shape of the scattered light. The results are of relevance for the future spaceborne lidars on ADM-Aeolus (Atmospheric Dynamics Mission) and EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer). PMID:20676176

  4. Calibration of a wide-field frequency-domain fluorescence lifetime microscopy system using light emitting diodes as light sources.

    PubMed

    Elder, A D; Frank, J H; Swartling, J; Dai, X; Kaminski, C F

    2006-11-01

    High brightness light emitting diodes are an inexpensive and versatile light source for wide-field frequency-domain fluorescence lifetime imaging microscopy. In this paper a full calibration of an LED based fluorescence lifetime imaging microscopy system is presented for the first time. A radio-frequency generator was used for simultaneous modulation of light emitting diode (LED) intensity and the gain of an intensified charge coupled device (CCD) camera. A homodyne detection scheme was employed to measure the demodulation and phase shift of the emitted fluorescence, from which phase and modulation lifetimes were determined at each image pixel. The system was characterized both in terms of its sensitivity to measure short lifetimes (500 ps to 4 ns), and its capability to distinguish image features with small lifetime differences. Calibration measurements were performed in quenched solutions containing Rhodamine 6G dye and the results compared to several independent measurements performed with other measurement methodologies, including time correlated single photon counting, time gated detection, and acousto optical modulator (AOM) based modulation of excitation sources. Results are presented from measurements and simulations. The effects of limited signal-to-noise ratios, baseline drifts and calibration errors are discussed in detail. The implications of limited modulation bandwidth of high brightness, large area LED devices ( approximately 40 MHz for devices used here) are presented. The results show that phase lifetime measurements are robust down to sub ns levels, whereas modulation lifetimes are prone to errors even at large signal-to-noise ratios. Strategies for optimizing measurement fidelity are discussed. Application of the fluorescence lifetime imaging microscopy system is illustrated with examples from studies of molecular mixing in microfluidic devices and targeted drug delivery research. PMID:17204064

  5. Fluorescent Carbon Quantum Dots as Single Light Converter for White LEDs

    NASA Astrophysics Data System (ADS)

    Feng, Xiaoting; Zhang, Feng; Wang, Yaling; Zhang, Yi; Yang, Yongzhen; Liu, Xuguang

    2016-06-01

    Synthesis of fluorescent carbon quantum dots (CQDs) as single light converter and their application in white light-emitting diodes (LEDs) are reported. CQDs were prepared by a one-step hydrothermal method using glucose and polyethylene glycol 200 as precursors. The structural and optical properties of the CQDs were investigated. The CQDs with uniform size of 4 nm possessed typical excitation-dependent emission wavelength and quantum yield of 3.5%. Under ultraviolet illumination, the CQDs in deionized water emitted bright blue fluorescence and produced broad visible-light emission with high red, green, and blue spectral component ratio of 63.5% (red-to-blue intensity to total intensity), suggesting great potential as single light converter for white LEDs. To demonstrate their potential, a white LED using CQDs as a single light converter was built. The device exhibited cool white light with corresponding color temperature of 5584 K and color coordinates of (0.32, 0.37), belonging to the white gamut. This research suggests that CQDs could be a promising candidate single light converter for white LEDs.

  6. Far-red light photoactivatable near-infrared fluorescent proteins engineered from a bacterial phytochrome

    PubMed Central

    Piatkevich, Kiryl D.; Subach, Fedor V.; Verkhusha, Vladislav V.

    2013-01-01

    Ability to modulate fluorescence of optical probes can be used to enhance signal-to-noise ratio for imaging within highly autofluorescent environments, such as intact tissues and living organisms. Here we report two phytochrome-based photoactivatable near-infrared fluorescent proteins, named PAiRFP1 and PAiRFP2. PAiRFPs utilize heme-derived biliverdin, ubiquitous in mammalian tissues, as the chromophore. Initially weakly fluorescent PAiRFPs undergo photoconversion into a highly fluorescent state with excitation/emission at 690 nm/717 nm following a brief irradiation with far-red light. After photoactivation, PAiRFPs slowly revert back to initial state, enabling multiple photoactivation-relaxation cycles. Low-temperature optical spectroscopy reveals several intermediates involved in PAiRFP photocycles, which all differ from that of the bacteriophytochrome precursor. PAiRFPs can be photoactivated in a spatially selective manner in mouse tissues, and optical modulation of their fluorescence allows for substantial contrast enhancement, making PAiRFPs advantageous over permanently fluorescent probes for in vivo imaging conditions of high autofluorescence and low signal levels. PMID:23842578

  7. [Normal light and fluorescence microscopy for authentication of Delphinii Brunoniani Herba of Tibet].

    PubMed

    Wang, Ya-Qiong; Xu, Fu-Chun; Dongzhi, Zhuo-Ma; Liu, E-Hu; Xu, Luo-Shan; Liu, Hui-Juan; Li, Ping

    2012-11-01

    Dried herb of Delphinium brunonianum Royle (Ranunculaceae) has long been used under the herbal name "Xiaguobei" (Delphinii Brunoniani Herba) in traditional Tibetan medicine and prescribed for the treatment of influenza, itchy skin rash and snake bites. In order to find a useful and convenient method for the identification of microscopic features, the technique of fluorescence microscopy was applied to authenticate "Xiaguobei" of Tibet. The transverse sections of stem and leaf, as well as the powder of "Xiaguobei" were observed to seek for typical microscopic features by normal light and fluorescence microscopy. A style-like, single-cell glandular hair containing yellow secretions on the leaf, young stem and sepal of "Xiaguobei" was found. Under the fluorescence microscope, the xylem and pericycle fiber group emitted significant fluorescence. This work indicated that fluorescence microscopy could be an useful additional method for the authentication work. Without the traditional dyeing methods, the main microscopic features could be easily found by fluorescence microscopy. The results provided reliable references for the authentication of "Xiaguobei". PMID:23387092

  8. Image-guided surgery using near-infrared fluorescent light: from bench to bedside

    NASA Astrophysics Data System (ADS)

    Boogerd, Leonora S. F.; Handgraaf, Henricus J. M.; van de Velde, Cornelis J. H.; Vahrmeijer, Alexander L.

    2015-03-01

    Due to its relatively high tissue penetration, near-infrared (NIR; 700-900 nm) fluorescent light has the potential to visualize structures that need to be resected (e.g. tumors, lymph nodes) and structures that need to be spared (e.g. nerves, ureters, bile ducts). Until now, most clinical trials have focused on suboptimal, non-targeted dyes. Although successful, a new era in image-guided surgery has begun by the introduction of tumor-targeted agents. In this paper, we will describe how tumor-targeted NIR fluorescent imaging can be applied in a clinical setting.

  9. Laser-induced fluorescence from N2(+) ions generated by a corona discharge in ambient air.

    PubMed

    Konthasinghe, Kumarasiri; Fitzmorris, Kristin; Peiris, Manoj; Hopkins, Adam J; Petrak, Benjamin; Killinger, Dennis K; Muller, Andreas

    2015-09-01

    In this work, we present the measurement of laser-induced fluorescence from N2(+) ions via the B(2)Σu(+)-X(2)Σg(+) band system in the near-ultraviolet. The ions were generated continuously by a plasma glow discharge in low pressure N2 and by a corona discharge in ambient air. The fluorescence decay time was found to rapidly decrease with increasing pressure leading to an extrapolated decay rate of ≍10(10) s(-1) at atmospheric pressure. In spite of this quenching, we were able to observe laser induced fluorescence in ambient air by means of a time-gated spectral measurement. In the process of comparing the emission signal with that of N2 spontaneous Raman scattering, ion concentrations in ambient air of order 10(8-)10(10) cm(-3) were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 10(6) cm(-3) may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources. PMID:26414524

  10. AIRS First Light Data: Eastern Mediterranean, June 14, 2002

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2Figure 3

    Four images of the Mediterranean obtained concurrently on June 14, 2002 from the three instruments that make up the Atmospheric Infrared Sounder experiment system aboard NASA's Aqua spacecraft. The system features thousands of individual channels that observe Earth in the visible, infrared and microwave spectral regions. Each channel has a unique sensitivity to temperature, moisture, surface conditions and clouds.

    This visible light image from the AIRS instrument shows a band of white clouds extending from the Adriatic Sea over Greece to the Black Sea.

    The AIRS image (figure 1) at 900 cm-1 (11 micrometers) measures actual surface or cloud top temperatures. In it, land and ocean boundaries are well defined, with land appearing as warmer (darker red) than the ocean. The band of cold high cumulus clouds appears blue, with the darkest blue most likely a large thunderstorm.

    The 150 gigahertz channel from the Humidity Sounder for Brazil instrument (figure 2) is sensitive to moisture, ice particles and precipitation. The dry land temperature is comparable to the 11 micrometer temperatures, but over ocean this channel measures the temperature of moisture in the mid troposphere. The cold, blue areas off Sicily and in the Aegean Sea represent unusually dry areas over the ocean. There, clouds appear as green filaments--likely areas of precipitation.

    The 31.4 gigahertz channel from the Advanced Microwave Sounding Unit instrument (figure 3) is not affected by clouds.

    NASA's Atmospheric Infrared Sounder (AIRS) onboard NASA's Aqua spacecraft, began sending high quality data on June 12, 2002. This 'first light' data is exceeding the expectations of scientists, confirming that the AIRS experiment is well on its way to meeting its goals of improving weather forecasting, establishing the connection between severe weather and

  11. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  12. The Effects of Very Light Jet Air Taxi Operations on Commercial Air Traffic

    NASA Technical Reports Server (NTRS)

    Smith, Jeremy C.; Dollyhigh, Samuel M.

    2006-01-01

    This study investigates the potential effects of Very Light Jet (VLJ) air taxi operations adding to delays experienced by commercial passenger air transportation in the year 2025. The affordable cost relative to existing business jets and ability to use many of the existing small, minimally equipped, but conveniently located airports is projected to stimulate a large demand for the aircraft. The resulting increase in air traffic operations will mainly be at smaller airports, but this study indicates that VLJs have the potential to increase further the pressure of demand at some medium and large airports, some of which are already operating at or near capacity at peak times. The additional delays to commercial passenger air transportation due to VLJ air taxi operations are obtained from simulation results using the Airspace Concepts Evaluation System (ACES) simulator. The direct increase in operating cost due to additional delays is estimated. VLJs will also cause an increase in traffic density, and this study shows increased potential for conflicts due to VLJ operations.

  13. Comparison of Light Emitting Diodes (LED) and Fluorescent Light on Suppression of Pineal Melatonin in the Rat

    NASA Technical Reports Server (NTRS)

    Winget, Charles M.; Heeke, D. S.; Holley, D. C.; Mele, G.; Brainard, G. C.; Hanifin, J. P.; Rollag, M. D.; Savage, Paul D. (Technical Monitor)

    1997-01-01

    To validate a novel LED array for use in animal habitat lighting by comparing its effectiveness to cool-white fluorescent (CWF) lighting in suppressing pineal gland melatonin. Male Sprague-Dawley rats, 175-200 g, were maintained under control conditions for 2 weeks (food and water ad lib, 12L: 12D CWF, 18 uW/square cm). Dark adapted animals (animals before lights on) were exposed to 5 min of LED or CWF light of similar spectral power distribution. Two groups of rats (LED vs. CWF) were compared at 5 light intensities (100, 40, 1, 1.0, and 0. 1 lux). A control group was placed into the exposure apparatus but not exposed to light. After exposure, pineal glands were rapidly removed and assayed for melatonin by RIA. Results. The dark-exposed control groups matched with the 5 intensity groups (100, 40, 10, 1.0, and 0.1 lux) showed mean + SEM pineal melatonin values of 1167 +/- 136, 1569 +/- 126, 353 +/- 34, 650 +/- 124, and 464 +/- 85, pg/ml respectively. The corresponding CWF exposure data were 393 1 41, 365 +34, 257 +/- 13, 218 +/- 42, and 239 +/- 71 pg/ml, respectively. Corresponding LED exposure data were 439 +/- 25, 462 +/- 50, 231 +/- 6, 164 +/- 12, and 158 +/- 12 pg/ml, respectively. Rats exposed to both experimental light conditions at all illuminances studied showed significant melatonin suppression (p less than 0.01, ANOVA). In no case was the melatonin suppression induced by LED illuminance significantly different from the melatonin suppression elicited by the same intensity of CWF light. The results show that a novel LED light source can suppress pineal melatonin equal to that of a conventional CWF light source.

  14. Life History Changes in Coral Fluorescence and the Effects of Light Intensity on Larval Physiology and Settlement in Seriatopora hystrix

    PubMed Central

    Roth, Melissa S.; Fan, Tung-Yung; Deheyn, Dimitri D.

    2013-01-01

    Fluorescence is common in both coral adult and larval stages, and is produced by fluorescent proteins that absorb higher energy light and emit lower energy light. This study investigated the changes of coral fluorescence in different life history stages and the effects of parental light environment on larval fluorescence, larval endosymbiotic dinoflagellate abundance, larval size and settlement in the brooding coral Seriatopora hystrix. Data showed that coral fluorescence changed during development from green in larvae to cyan in adult colonies. In larvae, two green fluorescent proteins (GFPs) co-occur where the peak emission of one GFP overlaps with the peak excitation of the second GFP allowing the potential for energy transfer. Coral larvae showed great variation in GFP fluorescence, dinoflagellate abundance, and size. There was no obvious relationship between green fluorescence intensity and dinoflagellate abundance, green fluorescence intensity and larval size, or dinoflagellate abundance and larval size. Larvae of parents from high and low light treatments showed similar green fluorescence intensity, yet small but significant differences in size, dinoflagellate abundance, and settlement. The large variation in larval physiology combined with subtle effects of parental environment on larval characteristics seem to indicate that even though adult corals produce larvae with a wide range of physiological capacities, these larvae can still show small preferences for settling in similar habitats as their parents. These data highlight the importance of environmental conditions at the onset of life history and parent colony effects on coral larvae. PMID:23544072

  15. Malignant melanoma in relation to moles, pigmentation, and exposure to fluorescent and other lighting sources.

    PubMed Central

    Elwood, J. M.; Williamson, C.; Stapleton, P. J.

    1986-01-01

    Interviews were performed on 83 patients with malignant melanoma, being 74% of all new NHS patients over a 33 month period who were resident in a defined area of Nottingham, and on age and sex matched controls chosen from all outpatients and inpatients of the same hospitals with the same area of residence. Significantly increased risks of melanoma were found in subjects with 3 or more raised moles on the upper arms (relative risk = 17.0), in association with heavy freckling of the face and arms, and with a tendency to sunburn easily and tan poorly, these factors having independent effects. While no significant and consistent association with exposure to fluorescent light was seen, the observed risks were higher in subjects with greater exposure, and higher in association with exposure to undiffused than to diffused light. Cases had a significantly greater number of hours' exposure to undiffused light than did controls. The associations with fluorescent light exposure were stronger when based on interview data than on a subsequent postal questionnaire. Twenty-one cases and 11 controls reported exposure to unusual occupational lighting sources which may have had an ultraviolet component; these included various intense lighting sources and lamps used in printing and dyeline copying. PMID:3947517

  16. Quantified light-induced fluorescence, review of a diagnostic tool in prevention of oral disease

    NASA Astrophysics Data System (ADS)

    de Josselin de Jong, Elbert; Higham, Susan M.; Smith, Philip W.; van Daelen, Catherina J.; van der Veen, Monique H.

    2009-05-01

    Diagnostic methods for the use in preventive dentistry are being developed continuously. Few of these find their way into general practice. Although the general trend in medicine is to focus on disease prevention and early diagnostics, in dentistry this is still not the case. Nevertheless, in dental research some of these methods seem to be promising for near future use by the general dental professional. In this paper an overview is given of a method called quantitative light-induced fluorescence or (QLF) in which visible and harmless light excites the teeth in the patient's mouth to produce fluorescent images, which can be stored on disk and computer analyzed. White spots (early dental caries) are detected and quantified as well as bacterial metabolites on and in the teeth. An overview of research to validate the technique and modeling to further the understanding of the technique by Monte Carlo simulation is given and it is shown that the fluorescence phenomena can be described by the simulation model in a qualitative way. A model describing the visibility of red fluorescence from within the dental tissue is added, as this was still lacking in current literature. An overview is given of the clinical images made with the system and of the extensive research which has been done. The QLF™ technology has been shown to be of importance when used in clinical trials with respect to the testing of toothpastes and preventive treatments. It is expected that the QLF™ technology will soon find its way into the general dental practice.

  17. Light-sheet-based fluorescence microscopy for three-dimensional imaging of biological samples.

    PubMed

    Swoger, Jim; Pampaloni, Francesco; Stelzer, Ernst H K

    2014-01-01

    In modern biology, most optical imaging technologies are applied to two-dimensional cell culture systems; that is, they are used in a cellular context that is defined by hard and flat surfaces. However, a physiological context is not found in single cells cultivated on coverslips. It requires the complex three-dimensional (3D) relationship of cells cultivated in extracellular matrix (ECM) gels, tissue sections, or in naturally developing organisms. In fact, the number of applications of 3D cell cultures in basic research as well as in drug discovery and toxicity testing has been increasing over the past few years. Unfortunately, the imaging of highly scattering multicellular specimens is still challenging. The main issues are the limited optical penetration depth, the phototoxicity, and the fluorophore bleaching. Light-sheet-based fluorescence microscopy (LSFM) overcomes many drawbacks of conventional fluorescence microscopy by using an orthogonal/azimuthal fluorescence arrangement with independent sets of lenses for illumination and detection. The basic idea is to illuminate the specimen from the side with a thin light sheet that overlaps with the focal plane of a wide-field fluorescence microscope. Optical sectioning and minimal phototoxic damage or photobleaching outside a small volume close to the focal plane are intrinsic properties of LSFM. We discuss the basic principles of LSFM and methods for the preparation, embedding, and imaging of 3D specimens used in the life sciences in an implementation of LSFM known as the single (or selective) plane illumination microscope (SPIM). PMID:24371323

  18. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

    PubMed Central

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

    2016-01-01

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5–12-fold compared with their conventional diffraction-limited LS analogs. PMID:26984498

  19. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

    NASA Astrophysics Data System (ADS)

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

    2016-03-01

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs.

  20. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT.

    PubMed

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J; Hell, Stefan W; Hufnagel, Lars

    2016-03-29

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs. PMID:26984498

  1. Simultaneous light scattering and intrinsic fluorescence measurement for the classification of airborne particles.

    PubMed

    Kaye, P H; Barton, J E; Hirst, E; Clark, J M

    2000-07-20

    We describe a prototype laboratory light-scattering instrument that integrates two approaches to airborne particle characterization: spatial light-scattering analysis and intrinsic fluorescence measurement, with the aim of providing an effective means of classifying biological particles within an ambient aerosol. The system uses a single continuous-wave 266-nm ultraviolet laser to generate both the spatial elastic scatter data (from which an assessment of particle size and shape is made) and the particle intrinsic fluorescence data from particles in the approximate size range of 1-10-mum diameter carried in a sample airflow through the laser beam. Preliminary results suggest that this multiparameter measurement approach can provide an effective means of classifying different particle types and can reduce occurrences of false-positive detection of biological aerosols. PMID:18349949

  2. Simultaneous Measurement of Amyloid Fibril Formation by Dynamic Light Scattering and Fluorescence Reveals Complex Aggregation Kinetics

    PubMed Central

    Streets, Aaron M.; Sourigues, Yannick; Kopito, Ron R.; Melki, Ronald; Quake, Stephen R.

    2013-01-01

    An apparatus that combines dynamic light scattering and Thioflavin T fluorescence detection is used to simultaneously probe fibril formation in polyglutamine peptides, the aggregating subunit associated with Huntington's disease, in vitro. Huntington's disease is a neurodegenerative disorder in a class of human pathologies that includes Alzheimer's and Parkinson's disease. These pathologies are all related by the propensity of their associated protein or polypeptide to form insoluble, β-sheet rich, amyloid fibrils. Despite the wide range of amino acid sequence in the aggregation prone polypeptides associated with these diseases, the resulting amyloids display strikingly similar physical structure, an observation which suggests a physical basis for amyloid fibril formation. Thioflavin T fluorescence reports β-sheet fibril content while dynamic light scattering measures particle size distributions. The combined techniques allow elucidation of complex aggregation kinetics and are used to reveal multiple stages of amyloid fibril formation. PMID:23349924

  3. Instrument for fluorescence sensing of circulating cells with diffuse light in mice in vivo

    NASA Astrophysics Data System (ADS)

    Zettergren, Eric; Vickers, Dwayne; Runnels, Judith; Murthy, Shashi K.; Lin, Charles P.; Niedre, Mark

    2012-03-01

    Accurate quantification of circulating cell populations in mice is important in many areas of preclinical biomedical research. Normally, this is done either by extraction and analysis of small blood samples or, more recently, by using microscopy-based in vivo fluorescence flow cytometry. We describe a new technological approach to this problem using detection of diffuse fluorescent light from relatively large blood vessels in vivo. The diffuse fluorescence flow cytometer (DFFC) uses a laser to illuminate a mouse limb and an array of optical fibers coupled to a high-sensitivity photomultiplier tube array operating in photon counting mode to detect weak fluorescence signals from cells. We first demonstrate that the DFFC instrument is capable of detecting fluorescent microspheres and Vybrant-DiD-labeled cells in a custom-made optical flow phantom with similar size, optical properties, linear flow rates, and autofluorescence as a mouse limb. We also present preliminary data demonstrating that the DFFC is capable of detecting circulating cells in nude mice in vivo. In principle, this device would allow interrogation of the whole blood volume of a mouse in minutes, with sensitivity improvement by several orders of magnitude compared to current approaches.

  4. Outbreak of illness due to volatilized asphalt coming from a malfunctioning fluorescent lighting fixture.

    PubMed Central

    Tavris, D R; Field, L; Brumback, C L

    1984-01-01

    We investigated an outbreak of headache, eye irritation, sore throat, nasal congestion, and nausea in an office complex, ongoing for three months and regularly resolved upon leaving the building. Investigation suggested that the etiology of the illness was malfunctioning fluorescent light ballasts , which overheated and resulted in melting and volatilization of contained asphalt . Correction of the problem resulted in almost complete disappearance of symptoms within two weeks. PMID:6721022

  5. Outbreak of illness due to volatilized asphalt coming from a malfunction fluorescent lighting fixture

    SciTech Connect

    Tavris, D.R.; Field, L.; Brumback, C.L.

    1984-06-01

    An investigation was made of an outbreak of headache, eye irritation, sore throat, nasal congestion, and nausea in an office complex, ongoing for three months and regularly resolved upon leaving the building. Investigation suggested that the etiology of the illness was malfunctioning fluorescent light ballasts, which overheated and resulted in melting and volatilization of contained asphalt. Correction of the problem resulted in almost complete disappearance of symptoms within two weeks.

  6. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence

    SciTech Connect

    Nishide, Jun-ichi; Hiraga, Yasuhide; Nakanotani, Hajime; Adachi, Chihaya

    2014-06-09

    White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

  7. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Nishide, Jun-ichi; Nakanotani, Hajime; Hiraga, Yasuhide; Adachi, Chihaya

    2014-06-01

    White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

  8. Artifactual formation of 8-oxo-2'-deoxyguanosine: role of fluorescent light and inhibitors.

    PubMed

    Arif, Jamal M; Gupta, Ramesh C

    2003-01-01

    The pro-mutagenic oxidative DNA lesion, 8-oxo-2'-deoxyguanosine (8-oxodG) has been a subject of numerous studies. However, the absolute 8-oxodG levels in tissue DNA reported by various methods have been debated due to its artifactual production during DNA isolation and/or the DNA processing. We have investigated factors that may result in such artifacts during isolation and analysis of DNA as well as means for its prevention. 8-OxodG content was measured by a recently described TLC enrichment-mediated 32P-postlabeling. Liver DNA from 3 month-old, female Sprague-Dawley rats was isolated by a standard solvent-extraction procedure (phenol, phenol:Sevag, and Sevag; 23 degrees C), a modified solvent-extraction procedure (phenol:Sevag, and Sevag; 4 degrees C; KCl-SDS-protein precipitation) or sodium iodide extraction procedure. 8-OxodG was analyzed in the DNA by the 32P-postlabeling assay using a fluorescent light box during the workup, as well as in its absence. The 8-oxodG levels, when the fluorescent light box was used, were in similar range irrespective of the DNA isolation procedure (16.4+/-1.6 to 28.7+/-6 8-oxodG/10(6) nucleotides). However, the values were significantly lower (3.1+/-0.4 to 3.4+/-0.2 8-oxodG/10(6) nucleotides) in the absence of fluorescence light box, room fluorescent light (suspended through the ceiling) and natural room light did not alter the 8-oxodG levels. Further, the addition of 0.3 mM of PBN (N-t-butyl-alpha-phenyl nitrone) or TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), or 6.8 mM 8-hydroxy-quinoline during the DNA isolation resulted in still lower values (0.8+/-0.1 to 1.8+/-0.5 8-oxodG/10(6) nucleotides) although this reduction was not consistently observed in different experiments. These results suggest that fluorescent light is the major 'culprit' in artifactual production and variability reported in the 8-oxodG levels. PMID:14534745

  9. Phantom and mouse experiments of time-domain fluorescence tomography using total light approach

    PubMed Central

    Okawa, Shinpei; Yano, Akira; Uchida, Kazuki; Mitsui, Yohei; Yoshida, Masaki; Takekoshi, Masashi; Marjono, Andhi; Gao, Feng; Hoshi, Yoko; Kida, Ikuhiro; Masamoto, Kazuto; Yamada, Yukio

    2013-01-01

    Phantom and mouse experiments of time-domain fluorescence tomography were conducted to demonstrate the total light approach which was previously proposed by authors. The total light approach reduces the computation time to solve the forward model for light propagation. Time-resolved temporal profiles were acquired for cylindrical phantoms having single or double targets containing indocyanine green (ICG) solutions. The reconstructed images of ICG concentration reflected the true distributions of ICG concentration with a spatial resolution of about 10 mm. In vivo experiments were conducted using a mouse in which an ICG capsule was embedded beneath the skin in the abdomen. The reconstructed image of the ICG concentration again reflected the true distribution of ICG although artifacts due to autofluorescence appeared in the vicinity of the skin. The effectiveness of the total light approach was demonstrated by the phantom and mouse experiments. PMID:23577297

  10. Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light.

    PubMed

    Wu, Qianyuan; Li, Chao; Wang, Wenlong; He, Tao; Hu, Hongying; Du, Ye; Wang, Ting

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change. PMID:27155416

  11. Theory of light quenching: effects of fluorescence polarization, intensity, and anisotropy decays.

    PubMed Central

    Kuśba, J; Bogdanov, V; Gryczynski, I; Lakowicz, J R

    1994-01-01

    Experimental studies have recently demonstrated that fluorescence emission can be quenched by laser light pulses from modern high repetition rate lasers, a phenomenon we call "light quenching." We now describe the theory of light quenching and some of its effects on the steady-state and time-resolved intensity and anisotropy decays of fluorophores. Light quenching can decrease or increase the steady-state or time-zero anisotropy. Remarkably, the light quenching can break the usual z axis symmetry of the excited-state population, and the emission polarization can range from -1 to +1 under selected conditions. The measured anisotropy (or polarization) depends upon whether the observation axis is parallel or perpendicular to the propagation direction of the light quenching beam. The effects of light quenching are different for a single pulse, which results in both excitation and quenching, as compared with a time-delayed quenching pulse. Time-delayed light quenching pulses can result in step-like changes in the time-dependent intensity or anisotropy and are predicted to cause oscillations in the frequency-domain intensity and anisotropy decays. The increasing availability of pulsed laser sources offers the opportunity for a new class of two-pulse or multiple-pulse experiments where the sample is prepared by an excitation pulse, the excited state population is modified by the quenching pulse(s), followed by time- or frequency-domain measurements of the resulting emission. PMID:7858140

  12. Stable blue thermally activated delayed fluorescent organic light-emitting diodes with three times longer lifetime than phosphorescent organic light-emitting diodes.

    PubMed

    Kim, Mounggon; Jeon, Sang Kyu; Hwang, Seok-Ho; Lee, Jun Yeob

    2015-04-17

    High quantum efficiency above 18% and extended lifetime three times longer than that of phosphorescent organic light-emitting diodes (OLEDs) are demonstrated in blue thermally activated delayed fluorescent OLEDs. PMID:25757226

  13. Synthesis of polymeric fluorescent brightener based on coumarin and its performances on paper as light stabilizer, fluorescent brightener and surface sizing agent

    NASA Astrophysics Data System (ADS)

    Zhang, Guanghua; Zheng, Hua; Guo, Mingyuan; Du, Lun; Liu, Guojun; Wang, Peng

    2016-03-01

    In this work, a novel polymeric fluorescent brightener based on coumarin (PFBC) was synthesized, using three-step synthetic route, from 7-amino-4-methylcoumarin, coumarin monomer (FBC), Acrylamide (AM) and methacrylatoethyl trimethyl ammonium chloride (DMC). The structure of PFBC was characterized by FT-IR, 1HNMR and GPC. PFBC was applied to paper fiber as light stabilizer, fluorescent brightener and surface sizing agent and its performances were evaluated by measuring the UV-vis, fluorescence, thermal stability, the cationic degree, surface strength and smoothness of paper, the brightness degree of paper and the PC value of paper. Results showed that PFBC had better solubility in water than that of FBC, by measuring the optical properties. Through the surface sizing experiment and UV aging experiment, PFBC not only enhanced the surface strength and smoothness of paper as a surface sizing agent, but also had better effect on anti-UV aging than that of FBC as light stabilizer and fluorescent brightener.

  14. A method for tuning the excitation wavelength of an LED light source during fluorescence-based cystoscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lindvold, Lars R.; Hermannn, Gregers G.

    2016-02-01

    In clinical applications of fluorescence-guided endoscopy of the bladder (cystoscopy) it can be observed that the contrast in light from autofluorescence and from photodynamic diagnosis (PDD) varies from patient to patient. To compensate for this effect, a new method is presented for tuning the wavelength of a LED-based light source during fluorescence guided endoscopy of the bladder i.e. photodynamic diagnosis of bladder tumours. In the present embodiment, the wavelength of the LED source, developed in our laboratory, can be tuned to vary the excitation wavelength of both the sensitised fluorescence in the tumours (PDD) as well as the native fluorescence of the bladder mucosa and blood vessels. The contrast of the image observed through the CCD-camera attached to the cystoscope is thereby increased. In this way, patient to patient variations in autofluorescence and in sensitised fluorescence of tumours can be compensated for during fluorescence-guided cystoscopy in the clinic.

  15. Filter-less fluorescence sensor with high separation ability achieved by the suppression of forward-scattered light in silicon

    NASA Astrophysics Data System (ADS)

    Choi, Yong Joon; Takahashi, Kazuhiro; Matsuda, Motoharu; Hizawa, Takeshi; Moriwaki, Yu; Dasai, Fumihiro; Kimura, Yasuyuki; Akita, Ippei; Iwata, Tatsuya; Ishida, Makoto; Sawada, Kazuaki

    2016-04-01

    The improvement of a filter-less fluorescence sensor, by suppressing forward scattering in silicon by surface planarization is presented. A fluorescence microscope has been widely used in biochemical fields. However, it is difficult to miniaturize because optical filters and other parts are necessary. We previously developed a filter-less fluorescence sensor. The separation ability of excitation light and fluorescence in the previous device was 550:1. It is necessary to improve the separation ability. This study focuses on the suppression of forward-scattered incident light in silicon, through the enhanced surface planarization of polysilicon, which is the gate electrode material. The separation ability of the filter-less fluorescence sensor was increased from 550:1 to 1250:1 by the suppression of forward-scattered light.

  16. Temperature measurements in hypersonic air flows using laser-induced O2 fluorescence

    NASA Technical Reports Server (NTRS)

    Laufer, Gabriel; Mckenzie, Robert L.

    1988-01-01

    An investigation is reported of the use of laser-induced fluorescence on oxygen for the measurement of air temperature and its fluctuations owing to turbulence in hypersonic wind tunnel flows. The results show that for temperatures higher than 60 K and densities higher than 0.01 amagat, the uncertainty in the temperature measurement can be less than 2 percent if it is limited by photon-statistical noise. The measurement is unaffected by collisional quenching and, if the laser fluence is kept below 1.5 J/sq cm, it is also unaffected by nonlinear effects which are associated with depletion of the absorbing states.

  17. Feasibility of measuring temperature and density fluctuations in air using laser-induced O2 fluorescence

    NASA Technical Reports Server (NTRS)

    Massey, G. A.; Lemon, C. J.

    1984-01-01

    A tunable line-narrowed ArF laser can selectively excite several rotation al lines of the Schumann-Runge band system of O2 in air. The resulting ultraviolet fluorescence can be monitored at 90 deg to the laser beam axis, permitting space and time resolved observation of density and temperature fluctuations in turbulence. Experiments and calculations show that + or - 1 K, + or - 1 percent density, 1 cu mm spatial, and 1 microsecond temporal resolution can be achieved simultaneously under some conditions.

  18. Low Light CMOS Contact Imager with an Integrated Poly-Acrylic Emission Filter for Fluorescence Detection

    PubMed Central

    Dattner, Yonathan; Yadid-Pecht, Orly

    2010-01-01

    This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert’s law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented. PMID:22399920

  19. AIRS First Light Data: Typhoon Ramasun, July 3, 2002

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2Figure 3

    Four images of Tropical Cyclone Ramasun were obtained July 3, 2002 by the Atmospheric Infrared Sounder experiment system onboard NASA's Aqua spacecraft. The AIRS experiment, with its wide spectral coverage in four diverse bands, provides the ability to obtain complete 3-D observations of severe weather, from the surface, through clouds to the top of the atmosphere with unprecedented accuracy. This accuracy is the key to understanding weather patterns and improving weather predictions.

    Viewed separately, none of these images can provide accurate 3-D descriptions of the state of the atmosphere because of interference from clouds. However, the ability to make simultaneous observations at a wide range of wavelengths allows the AIRS experiment to 'see' through clouds.

    This visible light picture from the AIRS instrument provides important information about the location of the cyclone, cloud structure and distribution.

    The AIRS instrument image at 900 cm-1 (Figure 1) is from a 10 micron transparent 'window channel' that is little affected by water vapor but still cannot see through clouds. In clear areas (like the eye of the cyclone and over northwest Australia) it measures a surface temperature of about 300K (color encoded red). In cloudy areas it measures the cloud top temperature, about 200K for the cyclone, which translates to a cloud top height of about 50,000 feet.

    On the other hand, most clouds are relatively transparent in microwave, and the Advanced Microwave Sounding Instrument channel image (Figure 2) can see through all but the densest clouds. For example, Taiwan, which is covered by clouds, is clearly visible.

    The Humidity Sounder for Brazil instrument channel (Figure 3), also in the microwave, is more sensitive to both clouds and humidity. Only in clear, dry regions, such as the eye of the cyclone or the

  20. The role of plasmonic resonance in enhancement of interaction of light and silver nanostructures in fluorescence

    NASA Astrophysics Data System (ADS)

    Guo, Shy-Haugh

    -coated silicon substrates and oxide-coated noble-metallic films. In analyzing these results we applied both the discrete dipole approximation (DDA)and finite difference time domain (FDTD)methods, calculating the electromagnetic field response of our arrays to incident light. Comparison between these calculations and experiment provides physical insight as to the mechanisms of nano-metal particle-enhanced fluorescence: our results indicate local field enhancement from silver nanoparticles is crucial in nMEF.

  1. Study and parametrization of the night sky background radiation spectrum in the range 3000-6000 Å, for use with air fluorescence detectors of UHECR

    NASA Astrophysics Data System (ADS)

    Moyssides, P. G.; Maltezos, S.; Fokitis, E.

    2005-01-01

    The fluorescence light, induced by showers of the extremely high energy cosmic rays, is produced through the excitation of, mainly, nitrogen molecules, atoms, and ions, in the atmosphere. The fluorescence telescopes of the Auger Project record this nitrogen radiation under the variable night sky optical noise (background radiation) and, therefore, the study of the latter is crucial. In this paper we present a parametrization of an experimental night sky background radiation spectrum that, to our knowledge, is being carried out for the first time, recorded in the range 3000-6000 Å. Although the parametrization described here refers to a particular spectrum, our results are generally applicable, and could be adapted to those prevailing in particular locations, where EAS fluorescence telescopes are operating if, in addition, the gradual time variations of the spectrum are taken into account. They could be useful in data analysis for the event reconstruction, during the operation of the fluorescence detector of the Auger Observatory, since they could be used for the experimental emulation of the optical noise. In addition, they could be used in the designing of air fluorescence observatory components, such as photomultipliers and their spectral sensitivity, as well as in the corresponding optical filters.

  2. Quantitative Light Fluorescence (QLF) and Polarized White Light (PWL) assessments of dental fluorosis in an epidemiological setting

    PubMed Central

    2012-01-01

    Background To determine if a novel dual camera imaging system employing both polarized white light (PWL) and quantitative light induced fluorescence imaging (QLF) is appropriate for measuring enamel fluorosis in an epidemiological setting. The use of remote and objective scoring systems is of importance in fluorosis assessments due to the potential risk of examiner bias using clinical methods. Methods Subjects were recruited from a panel previously characterized for fluorosis and caries to ensure a range of fluorosis presentation. A total of 164 children, aged 11 years (±1.3) participated following consent. Each child was examined using the novel imaging system, a traditional digital SLR camera, and clinically using the Dean’s and Thylstrup and Fejerskov (TF) Indices on the upper central and lateral incisors. Polarized white light and SLR images were scored for both Dean’s and TF indices by raters and fluorescence images were automatically scored using software. Results Data from 164 children were available with a good distribution of fluorosis severity. The automated software analysis of QLF images demonstrated significant correlations with the clinical examinations for both Dean’s and TF index. Agreement (measured by weighted Kappa’s) between examiners scoring clinically, from polarized photographs and from SLR images ranged from 0.56 to 0.92. Conclusions The study suggests that the use of a digital imaging system to capture images for either automated software analysis, or remote assessment by raters is suitable for epidemiological work. The use of recorded images enables study archiving, assessment by multiple examiners, remote assessment and objectivity due to the blinding of subject status. PMID:22607363

  3. Light-scattering submicroscopic particles as highly fluorescent analogs and their use as tracer labels in clinical and biological applications.

    PubMed

    Yguerabide, J; Yguerabide, E E

    1998-09-10

    Submicroscopic gold particle suspensions scatter colored light when illuminated with white light, and we have observed that a light-scattering gold particle suspension has the same appearance as a fluorescing solution. Thus, when illuminated by a narrow beam of white light, a 40-nm gold sol displays a clear (not cloudy), green scattered light (Tyndall) beam and has the same appearance as a fluorescing fluorescein solution. These, as well as other, observations have suggested to us that, in general, light-scattering particles can be treated as fluorescent analogs and used as fluorescent analog tracers in immuno- and DNA probe assays as well as in cell and molecular biology studies. Light-scattering particles are advantageous in these applications because particles such as gold and silver have very high light-scattering powers, which allows these particles to be easily detected, by light-scattering, at particle concentrations as low as 10(-16) M. The scattered light can be detected by the unaided eye for qualitative measurements or with a simple light-sensitive detector for quantitative measurements. Moreover, individual particles can be easily detected by eye or a video camera using a simple light microscope with a proper illuminating system. In addition, submicroscopic particles which scatter blue, green, yellow, orange, or red light can be readily synthesized. Antibodies, DNA probes, and other tracer substances can be readily attached to gold and other particles without altering their light-scattering properties. In this article we present the theory which allows one to predict the light-scattering properties of particles of different sizes and compositions and identify those particle sizes and compositions which appear most adequate for particular applications. Furthermore, we calculate molar extinction coefficients and emission efficiencies for particles of different sizes and compositions which allows us to compare the light-producing powers of these particles

  4. Spectral signatures of fluorescence and light absorption to identify crude oils found in the marine environment

    NASA Astrophysics Data System (ADS)

    Baszanowska, E.; Otremba, Z.

    2014-08-01

    To protect the natural marine ecosystem, it is necessary to continuously enhance knowledge of environmental contamination, including oil pollution. Therefore, to properly track the qualitative and quantitative changes in the natural components of seawater, a description of the essential spectral features describing petroleum products is necessary. This study characterises two optically-different types of crude oils (Petrobaltic and Romashkino) - substances belonging to multi-fluorophoric systems. To obtain the spectral features of crude oils, the excitation-emission spectroscopy technique was applied. The fluorescence and light absorption properties for various concentrations of oils at a stabilised temperature are described. Both excitation-emission spectra (EEMs) and absorption spectra of crude oils are discussed. Based on the EEM spectra, both excitation end emission peaks for the wavelengthindependent fluorescence maximum (Exmax/ Emmax) - characteristic points for each type of oil - were identified and compared with the literature data concerning typical marine chemical structures.

  5. A Combined Light Sheet Fluorescence and Differential Interference Contrast Microscope for Live Imaging of Multicellular Specimens

    PubMed Central

    Baker, Ryan P.; Taormina, Michael J.; Jemielita, Matthew; Parthasarathy, Raghuveer

    2014-01-01

    We describe a microscope capable of both light sheet fluorescence microscopy (LSFM) and differential interference contrast microscopy (DICM). The two imaging modes, which to the best of our knowledge have not previously been combined, are complementary: LSFM provides three-dimensional imaging of fluorescently labeled components of multicellular systems with high speed, large fields of view, and low phototoxicity, while DICM reveals the unlabeled neighborhood of tissues, organs, and other structures with high contrast and inherent optical sectioning. Use of a single Nomarski prism for DICM and a shared detection path for both imaging modes enables simple integration of the two techniques in one custom microscope. We provide several examples of the utility of the resulting instrument, focusing especially on the digestive tract of the larval zebrafish, revealing in this complex and heterogeneous environment anatomical features, the behavior of commensal microbes, immune cell motions, and more. PMID:25611324

  6. Imaging green fluorescent protein-labeled neurons using light and electron microscopy.

    PubMed

    Knott, Graham W

    2013-06-01

    The ability to observe axons and dendrites with transmission electron microscopy (EM) after they have been previously imaged live with laser-scanning microscopy is a useful technique to study their synaptic connectivity. This protocol provides a detailed method by which neurons that were imaged in a live brain or slice culture can be reimaged using EM. First, brain tissue expressing green fluorescent protein (GFP) is chemically fixed. Then, an immunocytochemistry process is used to render the fluorescent protein electron dense so that it can first be located using light microscopy and then serial thin-sectioned for EM so that the ultrastructure of specific parts of neurites can be analyzed in three dimensions. Patterns of blood vessels observed in the live brain are used to locate the previously imaged neurons. The method described here allows for a complete three-dimensional (3D) reconstruction to be made of the imaged structures from serial electron micrographs. PMID:23734023

  7. Focused fluorescence excitation with time-reversed ultrasonically encoded light and imaging in thick scattering media

    NASA Astrophysics Data System (ADS)

    Lai, Puxiang; Suzuki, Yuta; Xu, Xiao; Wang, Lihong V.

    2013-07-01

    Scattering dominates light propagation in biological tissue, and therefore restricts both resolution and penetration depth in optical imaging within thick tissue. As photons travel into the diffusive regime, typically 1 mm beneath human skin, their trajectories transition from ballistic to diffusive due to the increased number of scattering events, which makes it impossible to focus, much less track, photon paths. Consequently, imaging methods that rely on controlled light illumination are ineffective in deep tissue. This problem has recently been addressed by a novel method capable of dynamically focusing light in thick scattering media via time reversal of ultrasonically encoded (TRUE) diffused light. Here, using photorefractive materials as phase conjugate mirrors, we show a direct visualization and dynamic control of optical focusing with this light delivery method, and demonstrate its application for focused fluorescence excitation and imaging in thick turbid media. These abilities are increasingly critical for understanding the dynamic interactions of light with biological matter and processes at different system levels, as well as their applications for biomedical diagnosis and therapy.

  8. Teaching about photosynthesis with simple equipment: analysis of light-induced changes in fluorescence and reflectance of plant leaves.

    PubMed

    Björn, Lars Olof; Li, Shaoshan

    2013-10-01

    Solar energy absorbed by plants results in either reflection or absorption. The latter results in photosynthesis, fluorescence, or heat. Measurements of fluorescence changes have been used for monitoring processes associated with photosynthesis. A simple method to follow changes in leaf fluorescence and leaf reflectance associated with nonphotochemical quenching and light acclimation of leaves is described. The main equipment needed consists of a green-light emitting laser pointer, a digital camera, and a personal computer equipped with the camera acquisition software and the programs ImageJ and Excel. Otherwise, only commonly available cheap materials are required. PMID:23728512

  9. Two-photon fluorescence and confocal reflected light imaging of thick tissue structures

    NASA Astrophysics Data System (ADS)

    Kim, Ki H.; So, Peter T. C.; Kochevar, Irene E.; Masters, Barry R.; Gratton, Enrico

    1998-04-01

    The technology of two-photon excitation has opened a window of opportunity for developing non-invasive medical diagnostic tools capable of monitoring thick tissue biochemical states. Using cellular endogenous chromophores, (beta) -nicotinamide- adenine dinucleotide phosphate [NAD(P)H], the cellular metabolic rates in living human skin were determined. Although important functional information can be obtained from the fluorescence spectroscopy of endogenous chromophores, these chromophores are rather poor contrast enhancing agent for mapping cellular morphology. First, most endogenous chromophores are confined to the cellular cytoplasm which prevents the visualization of other cellular organelles. Second, there is significant variability in the distribution and the quantum yield of endogenous chromophores which depends on tissue biochemistry but prevents consistent comparison of cellular morphology. On the other hand, the deep tissue cellular morphology has been imaged with excellent resolution using reflected light confocal microscopy. In reflected light microscopy, the image contrast originates from the index of refraction differences of the cellular structures. The organelle boundaries with significant index differences such as the plasma membrane and the nucleus envelope can be consistently visualized. A combination of morphological and functional information is required for a thorough tissue study. This presentation describes the development of a new microscope which is capable of simultaneously collecting both two-photon fluorescence and confocal reflected light signals. Promising biomedical applications include the non-invasive diagnosis of skin cancer and the study of wound healing.

  10. Localization of fluorescently labeled structures in frozen-hydrated samples using integrated light electron microscopy.

    PubMed

    Faas, F G A; Bárcena, M; Agronskaia, A V; Gerritsen, H C; Moscicka, K B; Diebolder, C A; van Driel, L F; Limpens, R W A L; Bos, E; Ravelli, R B G; Koning, R I; Koster, A J

    2013-03-01

    Correlative light and electron microscopy is an increasingly popular technique to study complex biological systems at various levels of resolution. Fluorescence microscopy can be employed to scan large areas to localize regions of interest which are then analyzed by electron microscopy to obtain morphological and structural information from a selected field of view at nm-scale resolution. Previously, an integrated approach to room temperature correlative microscopy was described. Combined use of light and electron microscopy within one instrument greatly simplifies sample handling, avoids cumbersome experimental overheads, simplifies navigation between the two modalities, and improves the success rate of image correlation. Here, an integrated approach for correlative microscopy under cryogenic conditions is presented. Its advantages over the room temperature approach include safeguarding the native hydrated state of the biological specimen, preservation of the fluorescence signal without risk of quenching due to heavy atom stains, and reduced photo bleaching. The potential of cryo integrated light and electron microscopy is demonstrated for the detection of viable bacteria, the study of in vitro polymerized microtubules, the localization of mitochondria in mouse embryonic fibroblasts, and for a search into virus-induced intracellular membrane modifications within mammalian cells. PMID:23261400

  11. Comparing phototoxicity during the development of a zebrafish craniofacial bone using confocal and light sheet fluorescence microscopy techniques.

    PubMed

    Jemielita, Matthew; Taormina, Michael J; Delaurier, April; Kimmel, Charles B; Parthasarathy, Raghuveer

    2013-12-01

    The combination of genetically encoded fluorescent proteins and three-dimensional imaging enables cell-type-specific studies of embryogenesis. Light sheet microscopy, in which fluorescence excitation is provided by a plane of laser light, is an appealing approach to live imaging due to its high speed and efficient use of photons. While the advantages of rapid imaging are apparent from recent work, the importance of low light levels to studies of development is not well established. We examine the zebrafish opercle, a craniofacial bone that exhibits pronounced shape changes at early developmental stages, using both spinning disk confocal and light sheet microscopies of fluorescent osteoblast cells. We find normal and aberrant opercle morphologies for specimens imaged with short time intervals using light sheet and spinning disk confocal microscopies, respectively, under equivalent exposure conditions over developmentally-relevant time scales. Quantification of shapes reveals that the differently imaged specimens travel along distinct trajectories in morphological space. PMID:23242824

  12. MUTATION SPECTRA IN SALMONELLA OF SUNLIGHT, WHITE FLUORESCENT LIGHT, AND LIGHT FROM TANNING SALON BEDS: INDUCTION OF TANDEM MUTATIONS AND ROLE OF DNA REPAIR

    EPA Science Inventory

    We evaluated the mutagenicity of sunlight (SUN), uncovered cool white fluorescent light (FLR), and light from a tanning salon bed (TAN) at the base-substitution allele hisG46 of Salmonella in four DNA repair backgrounds (wild type, uvrB, pKM101, and uvrB+pKM101). Approximately 80...

  13. Integrated OLED as excitation light source in fluorescent lateral flow immunoassays.

    PubMed

    Venkatraman, Vishak; Steckl, Andrew J

    2015-12-15

    The integration of organic light emitting diodes (OLEDs) as excitation light sources for quantum dot-based fluorescent lateral flow immunoassay systems (LFIA) was investigated. This approach has the potential to deliver a sensitive visible detection scheme for low-cost, disposable lab-on-chip point-of-care (POC) diagnosis system. Thin film phosphorescent green OLEDs fabricated on plastic substrates were integrated on-chip to excite the test line of a quantum dot-based LFIA (QD-LFIA). OLEDs were fabricated by sequential deposition of organic thin films (total of ~100 nm) onto ITO-coated PET substrates. CdSe/ZnS QDs emitting at 655 nm and Au nanoparticles (NP - 10 nm size) conjugated antibodies were used for the fluorescence QD-LFIA and conventional reflection-mode Au NP-LFIA, respectively. Thin plastic color light filters were integrated for filtering the excitation light source and, thereby, increasing the contrast of the emitted light for optimized visual detection. Integration of the OLED and color filters with the analytical membrane was achieved using adhesive techniques facilitated by the planar nature of the layers, which suggests possible large scale manufacturing using roll-to-roll processing. Gray scale analysis from digital images captured with a digital camera was used to quantify the visual sensitivity. The signal intensity, signal-to-noise ratio (SNR) and the limit of detection (LOD) of OLED integrated QD-LFIAs were compared to Au NP LFIAs. OLED QD-LFIA exhibited superior performance in all signal aspects: 7-8× higher signal intensity and SNR, and a 7× lower LOD of 3 nM (measured at S/N=3). These results demonstrate the potential of OLED-integrated in LFIA devices for obtaining sensitive, fast and low-cost POC diagnostics. PMID:26134292

  14. The Effect of Time on Bone Fluorescence: Implications for Using Alternate Light Sources to Search for Skeletal Remains.

    PubMed

    Swaraldahab, Mohamed A H; Christensen, Angi M

    2016-03-01

    Bones fluoresce when exposed to certain wavelengths of shortwave light, and this property can be useful in locating and sorting skeletal remains in forensic contexts. The proteins in bone collagen are largely responsible for its fluorescent properties, but these proteins degrade and denature over time. This study examined the fluorescence of bones from four temporal groups (recent, semi-recent, ancient, and historic) ranging from 0 to 1064 years before present. Specimens were photographed under 490 nm wavelength light, and fluorescence was quantified by converting intensity to a gray scale value based on the RGB color model using ImageJ(®) software. Significant (p < 0.05) differences were found in mean fluorescence between all four temporal groups, and a 0.324 coefficient of correlation indicates a significant (inverse) relationship between fluorescence and time. Bone fluorescence decreases with time, but some fluorescence is retained even in older samples. Fluorescence can therefore be reliably used in many modern skeletal remains searches. PMID:27404617

  15. Light-assisted non-Poissonian fluorescence blinking from bosonic composite reservoirs

    SciTech Connect

    Budini, Adrian A.

    2007-08-15

    Single fluorophore systems attached to complex hosting molecules may exhibit a light-assisted fluorescence blinking phenomenon between two or more different intensity states whose sojourn statistic depends on the pumping laser intensity and also may depart from an exponential law. In contrast with standard phenomenological models, here we demonstrate that such kind of radiation patterns can be microscopically derived and characterized by describing the fluorophore decay through a composite reservoir where quantum degrees of freedom associated to the host molecule mediate the interaction between the fluorophore and a bosonic bath associated to its natural decay.

  16. Obstacles and opportunities in the commercialization of the solid-state-electronic fluorescent-lighting ballast

    SciTech Connect

    Johnson, D.R.; Marcus, A.A.; Campbell, R.S.; Sommers, P.; Skumatz, L.; Berk, B.; Petty, P.; Eschbach, C.

    1981-10-01

    The Solid State Ballast (SSB) Program, aimed at improving the efficiency of fluorescent lights, is described. The first generation of solid state electronic ballasts has been developed and the technology has been transferred to the private sector. This report examines the opportunities for rapid dissemination of this technology into the marketplace. It includes a description of product characteristics and their influence on the commercialization of the SSB, a description of the technology delivery system presently used by the ballast industry, an analysis of the market for SSB, and identification of some high-leverage opportunities to accelerate the commercialization process. (MCW)

  17. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    NASA Astrophysics Data System (ADS)

    Groppo, D. P.; Caldas, L. V. E.

    2016-07-01

    The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source (90Sr+90Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed.

  18. Compact Fluorescent Lighting in America: Lessons Learned on the Way to Market

    SciTech Connect

    Sandahl, Linda J.; Gilbride, Theresa L.; Ledbetter, Marc R.; Steward, Heidi E.; Calwell, Chris

    2006-05-22

    This report describes the history of compact fluorescent lamps (CFLs) in America. CFLs were introduced in the 1970s; however, it has taken more than 20 years for them to gain widespread recognition in the U.S. residential lighting market. This report reviews the development of CFLs, efforts to increase market acceptance of them, and barriers to that acceptance. Lessons to be learned from this study of CFLs are identified in hopes of assisting future market introduction efforts for other promising energy-efficient technologies. This report was prepared by the Pacific Northwest National Laboratory for the U.S. Department of Energy’s Office of Building Technologies, Emerging Technologies Program.

  19. Fluorescence molecular tomography on animal model by means of multiple views structured light illumination

    NASA Astrophysics Data System (ADS)

    Ducros, N.; Bassi, A.; Valentini, G.; Canti, G.; Arridge, S.; D'Andrea, C.

    2013-03-01

    Fluorescence molecular tomography (FMT) is quite demanding in terms of acquisition/computational times due to the huge amount of data. Different research groups have proposed compression approaches regarding both illumination (wide field structured light instead of raster point scanning) and detection (compression of the acquired images). The authors have previously proposed a fast FMT reconstruction method based on the combination of a multiple-view approach with a full compression scheme. This method had been successfully tested on a cylindrical phantom and is being generalized in this paper to samples of arbitrary shape. The devised procedure and algorithms have been tested on an ex-vivo mouse.

  20. Obstacles and opportunities in the commercialization of the solid state electronic fluorescent lighting ballast

    NASA Astrophysics Data System (ADS)

    Johnson, D. R.; Marcus, A. A.; Campbell, R. S.; Sommers, P.; Skumatz, L.; Berk, B.; Petty, P.; Eschbach, C.

    1981-10-01

    A solid state ballast (SSB), which improves the efficiency of fluorescent lights, is described. The first generation of solid state electronic ballasts was developed and the technology was transferred to the private sector. The opportunities for rapid dissemination of this technology into the marketplace is examined. Product characteristics and their influence on the commercialization of the SSB, a description of the technology delivery system presently used by the ballast industry, an analysis of the market for SSB, and identification of some high leverage opportunities to accelerate the commercialization process are included.

  1. Shelf life of fresh meat products under LED or fluorescent lighting.

    PubMed

    Steele, K S; Weber, M J; Boyle, E A E; Hunt, M C; Lobaton-Sulabo, A S; Cundith, C; Hiebert, Y H; Abrolat, K A; Attey, J M; Clark, S D; Johnson, D E; Roenbaugh, T L

    2016-07-01

    Enhanced pork loin chops, beef longissimus lumborum steaks, semimembranosus steaks (superficial and deep portions), ground beef, and ground turkey were displayed under light emitting diode (LED) and fluorescent (FLS) lighting in two multi-shelf, retail display cases with identical operating parameters. Visual and instrumental color, internal product temperature, case temperature, case cycling, thiobarbituric acid reactive substances (TBARS), and Enterobacteriaceae and aerobic plate counts were evaluated. Under LED, beef products (except the deep portion of beef semimembranosus steaks) showed less (P<0.05) visual discoloration. Pork loin chops had higher (P<0.05) L* values for LED lighting. Other than beef longissimus lumborum steaks, products displayed under LED lights had colder internal temperatures than products under FLS lights (P<0.05). Under LED, pork loin chops, ground turkey, and beef semimembranosus steaks had higher (P<0.05) values for TBARS. LED provides colder case and product temperatures, more case efficiency, and extended color life by at least 0.5d for longissimus and semimembranosus steaks; however, some LED cuts showed increased lipid oxidation. PMID:26950612

  2. Efficient White-Light Generation from Ionically Self-Assembled Triply-Fluorescent Organic Nanoparticles.

    PubMed

    Das, Susmita; Debnath, Tanay; Basu, Amrita; Ghosh, Deepanwita; Das, Abhijit Kumar; Baker, Gary A; Patra, Amitava

    2016-06-20

    Low cost, simple, and environmentally friendly strategies for white-light generation which do not require rare-earth phosphors or other toxic or elementally scare species remain an essentially unmet challenge. Progress in the area of all-organic approaches is highly sought, single molecular systems remaining a particular challenge. Taking inspiration from the designer nature of ionic-liquid chemistry, we now introduce a new strategy toward white-light emission based on the facile generation of nanoparticles comprising three different fluorophores assembled in a well-defined stoichiometry purely through electrostatic interactions. The building blocks consist of the fluorophores aminopyrene, fluorescein, and rhodamine 6G which represent blue, green, and red-emitting species, respectively. Spherical nanoparticles 16(±5) nm in size were prepared which display bright white-light emission with high fluorescence quantum efficiency (26 %) and color coordinate at (0.29, 0.38) which lie in close proximity to pure white light (0.33, 0.33). It is noteworthy that this same fluorophore mixture in free solution yields only blue emission. Density functional theory calculations reveal H-bond and ground-state proton transfer mediated absolute non-parallel orientation of the constituent units which result in frustrated energy transfer, giving rise to emission from the individual centers and concomitant white-light emission. PMID:27219524

  3. UV-A emission from fluorescent energy-saving light bulbs alters local retinoic acid homeostasis.

    PubMed

    Hellmann-Regen, Julian; Heuser, Isabella; Regen, Francesca

    2013-12-01

    Worldwide bans on incandescent light bulbs (ILBs) drive the use of compact fluorescent light (CFL) bulbs, which emit ultraviolet (UV) radiation. Potential health issues of these light sources have already been discussed, including speculation about the putative biological effects on light exposed tissues, yet the underlying mechanisms remain unclear. We hypothesized photoisomerization of all-trans retinoic acid (at-RA), a highly light sensitive morphogen, into biologically less active isomers, as a mechanism mediating biological effects of CFLs. Local at-RA is anti-carcinogenic, entrains molecular rhythms and is crucial for skin homeostasis. Therefore, we quantified the impact of CFL irradiation on extra- and intracellular levels of RA isomers using an epidermal cell culture model. Moreover, a biologically relevant impact of CFL irradiation was assessed using highly at-RA-sensitive human neuroblastoma cells. Dose-dependent conversion of extra- and intracellular at-RA into the biologically less active 13-cis-isomer was significantly higher in CFL vs. ILB exposure and completely preventable by employing a UV-filter. Moreover, pre-irradiation of culture media by CFL attenuated at-RA-specific effects on cell viability in human at-RA-sensitive cells in a dose-dependent manner. These findings point towards a biological relevance of CFL-induced at-RA decomposition, providing a mechanism for CFL-mediated effects on environmental health. PMID:24135972

  4. The health risks associated with energy efficient fluorescent, LEDs, and artificial lighting

    NASA Astrophysics Data System (ADS)

    Panahi, Allen

    2014-09-01

    With the phasing out of incandescent lamps in many countries, the introduction of new LED based light sources and luminaries sometimes raise the question of whether the spectral characteristics of the LED and other energy savings Fluorescent lights including the popular CFLs are suitable to replace the traditional incandescent lamps. These concerns are sometimes raised particularly for radiation emissions in the UV and Blue parts of the spectrum. This paper aims to address such concerns for the common `white light' sources typically used in household and other general lighting used in the work place. Recent studies have shown that women working the night shift have an increased probability of developing breast cancer. We like to report on the findings of many studies done by medical professionals, in particular the recent announcement of AMA in the US and many studies conducted in the UK, as well as the European community to increase public awareness on the long term health risks of the optical and opto-biological effects on the human health caused by artificial lighting.

  5. Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

    2012-01-01

    The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

  6. Light-dependent regulation of structural flexibility in a photochromic fluorescent protein

    PubMed Central

    Mizuno, Hideaki; Mal, Tapas Kumar; Wälchli, Markus; Kikuchi, Akihiro; Fukano, Takashi; Ando, Ryoko; Jeyakanthan, Jeyaraman; Taka, Junichiro; Shiro, Yoshitsugu; Ikura, Mitsuhiko; Miyawaki, Atsushi

    2008-01-01

    The structural basis for the photochromism in the fluorescent protein Dronpa is poorly understood, because the crystal structures of the bright state of the protein did not provide an answer to the mechanism of the photochromism, and structural determination of the dark state has been elusive. We performed NMR analyses of Dronpa in solution at ambient temperatures to find structural flexibility of the protein in the dark state. Light-induced changes in interactions between the chromophore and β-barrel are responsible for switching between the two states. In the bright state, the apex of the chromophore tethers to the barrel by a hydrogen bond, and an imidazole ring protruding from the barrel stabilizes the plane of the chromophore. These interactions are disrupted by strong illumination with blue light, and the chromophore, together with a part of the β-barrel, becomes flexible, leading to a nonradiative decay process. PMID:18574155

  7. Imaging of human differentiated 3D neural aggregates using light sheet fluorescence microscopy

    PubMed Central

    Gualda, Emilio J.; Simão, Daniel; Pinto, Catarina; Alves, Paula M.; Brito, Catarina

    2014-01-01

    The development of three dimensional (3D) cell cultures represents a big step for the better understanding of cell behavior and disease in a more natural like environment, providing not only single but multiple cell type interactions in a complex 3D matrix, highly resembling physiological conditions. Light sheet fluorescence microscopy (LSFM) is becoming an excellent tool for fast imaging of such 3D biological structures. We demonstrate the potential of this technique for the imaging of human differentiated 3D neural aggregates in fixed and live samples, namely calcium imaging and cell death processes, showing the power of imaging modality compared with traditional microscopy. The combination of light sheet microscopy and 3D neural cultures will open the door to more challenging experiments involving drug testing at large scale as well as a better understanding of relevant biological processes in a more realistic environment. PMID:25161607

  8. Effects of fluorescent lighting on in vitro micropropagation of Lemna minor

    NASA Astrophysics Data System (ADS)

    Somsri, Kollawat; Pinyopich, Pataradawn; Mohammed, Waleed S.

    2010-05-01

    The vegetative in vitro propagation of Lemna minor stain SING-4 exposed to two different types of fluorescent light sources, Philips TLD 36W/54 and Toshiba FL40T8BRF/36, was studied. The liquid culture medium contained 4.43gl-1 phytohormone-free full-strength Murashige & Skoog (MS) basal medium with vitamins, 30gl-1 sucrose, and 1gl-1 MES. The results showed that both plant cultures had undergone normal asexual reproduction with an exponential increase trend. Cultures exposed to Toshiba FL40T8BRF/36 reproduced at a slightly faster rate while expressing significantly greener foliage (leaf color chart shade No.8), which indicates the presence of more chlorophyll, than cultures exposed to Philips TLD 36W/54 (leaf color chart shade No.4). The data obtained from our experiment reveals that light emitted from Toshiba FL40T8BRF/36 produces healthier and higher quality cultures.

  9. Modeling of fluorescence quenching by lutein in the plant light-harvesting complex LHCII.

    PubMed

    Duffy, C D P; Chmeliov, J; Macernis, M; Sulskus, J; Valkunas, L; Ruban, A V

    2013-09-26

    Photoprotective non-photochemical quenching (NPQ) in higher plants is the result of the formation of energy quenching traps in the light-harvesting antenna of photosystem II (PSII). It has been proposed that this quenching trap is a lutein molecule closely associated with the chlorophyll terminal emitter of the major light-harvesting complex LHCII. We have used a combination of time-dependent density functional theory (TD-DFT) and the semiempirical MNDO-CAS-CI method to model the chlorophyll-lutein energy transfer dynamics of the highly quenched crystal structure of LHCII. Our calculations reveal that the incoherent "hopping" of energy from Chla612 to the short-lived, dipole forbidden 2(1)A(g)(-) state of lutein620 accounts for the strong fluorescence quenching observed in these crystals. This adds weight to the argument that the same dissipative pathway is responsible for in vivo NPQ. PMID:23234311

  10. Oligomeric state of lipocalin-1 (LCN1) by multiangle laser light scattering and fluorescence anisotropy decay.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Merschak, Petra; Redl, Bernhard; Glasgow, Ben J

    2007-10-01

    Multiangle laser light scattering and fluorescence anisotropy decay measurements clarified the oligomeric states of native and recombinant tear lipocalin (lipocalin-1, TL). Native TL is monomeric. Recombinant TL (5-68 microM) with or without the histidine tag shows less than 7% dimer formation that is not in equilibrium with the monomeric form. Fluorescence anisotropy decay showed a correlation time of 9-10 ns for TL (10 microM-1 mM). Hydrodynamic calculations based on the crystallographic structure of a monomeric TL mutant closely concur with the observed correlation time. The solution properties calculated with HYDROPRO and SOLPRO programs from the available crystallographic structure of a monomeric TL mutant concur closely with the observed fluorescence anisotropy decay. The resulting model shows that protein topology is the major determinant of rotational correlation time and accounts for deviation from the Stokes-Einstein relation. The data challenge previous gel filtration studies to show that native TL exists predominantly as a monomer in solution rather than as a dimer. Delipidation of TL results in a formation of a complex oligomeric state (up to 25%). These findings are important as the dynamic processes in the tear film are limited by diffusional, translational as well as rotational, properties of the protein. PMID:17869594

  11. Oligomeric State of Lipocalin-1 (LCN1) by Multiangle Laser Light Scattering and Fluorescence Anisotropy Decay

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Merschak, Petra; Redl, Bernhard; Glasgow, Ben J.

    2007-01-01

    Multiangle laser light scattering and fluorescence anisotropy decay measurements clarified the oligomeric states of native and recombinant tear lipocalin (lipocalin-1, TL). Native TL is monomeric. Recombinant TL (5-68 μM) with or without the histidine tag shows less than 7% dimer formation that is not in equilibrium with the monomeric form. Fluorescence anisotropy decay showed a correlation time of 9-10 ns for TL (10 μM- 1mM). Hydrodynamic calculations based on the crystallographic structure of a monomeric TL mutant closely concur with the observed correlation time. The solution properties calculated with HYDROPRO and SOLPRO programs from the available crystallographic structure of a monomeric TL mutant concur closely with the observed fluorescence anisotropy decay. The resulting model shows that protein topology is the major determinant of rotational correlation time and accounts for deviation from the Stokes-Einstein relation. The data challenge previous gel filtration studies to show that native TL exists predominantly as a monomer in solution rather than as a dimer. Delipidation of TL results in a formation of a complex oligomeric state (up to 25%). These findings are important as the dynamic processes in the tear film are limited by diffusional, translational as well as rotational, properties of the protein. PMID:17869594

  12. MACROscopic imaging of tumor xenografts using fluorescence, phase contrast, and transmitted light

    NASA Astrophysics Data System (ADS)

    Constantinou, Paul; Nicklee, Trudey; Hedley, David W.; Wilson, Brian C.; Damaskinos, Savvas

    2004-10-01

    Recent advances in imaging technology have contributed greatly to biological science. Confocal fluorescence microscopes (CFM) can acquire 2D and 3D images of biological samples such as live or fixed cells and tissues. Specimens that are large (e.g., a 10 mm x 10 mm tissue section) and overfill the field of view (FOV) of typical microscope objectives require use of image tiling to cover the entire specimen. This can be time consuming and cause artefacts in the composite image. The MACROscope system (Biomedical Photometrics Inc, Waterloo, Canada), is a confocal device with a 22 mm x 70 mm FOV; ideal for imaging large tissue sections in a single frame. The system used here is a prototype capable of simultaneous acquisition from up to three detection channels. Fluorescence images of SiHa mouse tumour xenografts stained with CD31-Cy3, showing blood vessel location, and EF5-Cy5, showing areas of tissue hypoxia, were collected. Differential phase contrast (DPC) images of the same section were also recorded to show tissue morphology. Finally, RGB transmitted light images of human tongue and pancreas tissues were obtained. This new device avoids the need for image tiling and provides simultaneous imaging of multiple fluorescently-labeled tissue specific markers in large biological samples. This enables time- and cost-efficient high-throughput screening of (immuno)histopathological samples. This device may also serve in the imaging of high-throughput DNA and tissue arrays.

  13. Use of quantitative light-induced fluorescence to monitor tooth whitening

    NASA Astrophysics Data System (ADS)

    Amaechi, Bennett T.; Higham, Susan M.

    2001-04-01

    The changing of tooth shade by whitening agents occurs gradually. Apart from being subjective and affected by the conditions of the surroundings, visual observation cannot detect a very slight change in tooth color. An electronic method, which can communicate the color change quantitatively, would be more reliable. Quantitative Light- induced Fluorescence (QLF) was developed to detect and assess dental caries based on the phenomenon of change of autofluorescence of a tooth by demineralization. However, stains on the tooth surface exhibit the same phenomenon, and therefore QLF can be used to measure the percentage fluorescence change of stained enamel with respect to surrounding unstained enamel. The present study described a technique of assessing the effect of a tooth-whitening agent using QLF. This was demonstrated in two experiments in which either wholly or partially stained teeth were whitened by intermittent immersion in sodium hypochlorite. Following each immersion, the integrated fluorescence change due to the stain was quantified using QLF. In either situation, the value of (Delta) Q decreased linearly as the tooth regained its natural shade. It was concluded that gradual changing of the shade of discolored teeth by a whitening agent could be quantified using QLF.

  14. Lighting Up Clostridium Difficile: Reporting Gene Expression Using Fluorescent Lov Domains

    PubMed Central

    Buckley, Anthony M.; Jukes, Caitlin; Candlish, Denise; Irvine, June J.; Spencer, Janice; Fagan, Robert P.; Roe, Andrew J.; Christie, John M.; Fairweather, Neil F.; Douce, Gillian R.

    2016-01-01

    The uses of fluorescent reporters derived from green fluorescent protein have proved invaluable for the visualisation of biological processes in bacteria grown under aerobic conditions. However, their requirement for oxygen has limited their application in obligate anaerobes such as Clostridium difficile. Fluorescent proteins derived from Light, Oxygen or Voltage sensing (LOV) domains have been shown to bridge this limitation, but their utility as translational fusions to monitor protein expression and localisation in a strict anaerobic bacterium has not been reported. Here we demonstrate the utility of phiLOV in three species of Clostridium and its application as a marker of real-time protein translation and dynamics through genetic fusion with the cell division protein, FtsZ. Time lapse microscopy of dividing cells suggests that Z ring assembly arises through the extension of the FtsZ arc starting from one point on the circumference. Furthermore, through incorporation of phiLOV into the flagella subunit, FliC, we show the potential of bacterial LOV-based fusion proteins to be successfully exported to the extracellular environment. PMID:26996606

  15. Probing the mechanisms of an air amplifier using a LTQ-FT-ICR-MS and fluorescence spectroscopy.

    PubMed

    Dixon, R Brent; Muddiman, David C; Hawkridge, Adam M; Fedorov, A G

    2007-11-01

    We report the first quantitative assessment of electrosprayed droplet/ion focusing enabled by the use of a voltage-assisted air amplifier between an electrospray ionization emitter and a hybrid linear ion trap Fourier transform ion cyclotron resonance mass spectrometer (ESI-LTQ-FT-ICR-MS). A solution of fluorescent dye was electrosprayed with a stainless steel mesh screen placed in front of the MS inlet capillary acting as a gas-permeable imaging plate for fluorescence spectroscopy. Without use of the air amplifier, no detectable FT-ICR signal was observed, as well as no detectable fluorescence on the screen upon imaging using a fluorescence scanner. When the air amplifier was turned ON while electrospraying the fluorescent dye, FT-ICR mass spectra with high signal to noise ratio were obtained with an average ion injection time of 21 ms for an AGC target value of 5 x 10(5). Imaging of the screen using a fluorescence scanner produced a distinct spot of cross-sectional area approximately 33.5 mm(2) in front of the MS inlet capillary. These experimental results provide direct evidence of aerodynamic focusing of electrosprayed droplets/ions enabled by an air amplifier, resulting in improved electrospray droplet/ion capture efficiency and reduced ion injection time. A second set of experiments was carried out to explore whether the air amplifier assists in desolvation. By electrospraying a mix of quaternary amines, ratios of increasingly hydrophobic molecules were obtained. Observation of the solvophobic effect associated with electrospray ionization resulted in a higher abundance of the hydrophobic molecule. This bias was eliminated when the air amplifier was turned ON and a response indicative of the respective component concentrations of the molecules in the bulk solution was observed. PMID:17855111

  16. Polychromatic light-emitting diodes with a fluorescent nanosphere opal coating

    NASA Astrophysics Data System (ADS)

    Hui, K. N.; Fu, W. Y.; Ng, W. N.; Leung, C. H.; Lai, P. T.; Wong, K. K. Y.; Choi, H. W.

    2008-09-01

    A hexagonally close-packed array consisting of fluorescent nanospheres was coated onto short-wavelength GaN light-emitting diodes to demonstrate polychromatic white light emission. The spherical particles self-assemble into ordered three-dimensional opal structures, performing the role of color conversion to generate a polychromatic spectrum with smooth and uniform emission patterns. Different ratios of green and orange-red fluorescent nanospheres were mixed and coated onto high-extraction-efficiency micro-LEDs. Four devices with different shades of white emission were demonstrated. Device A, with a high content of orange-red nanospheres, offers the highest CRI value of 80, whereas device C with a well-balanced ratio of green and orange-red nanospheres exhibits color characteristics closest to ideal white with CIE coordinate at (0.34, 0.34). At 20 mA driving current, the luminous efficacy of the devices A, B, C, and D are 40.5 lm W-1, 57.7 lm W-1, 63.1 lm W-1, and 67.2 lm W-1 respectively, while the correlated color temperatures (CCTs) of the corresponding devices are 3587, 4778, 5271, and 13 000 K.

  17. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    PubMed

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  18. Highly efficient white organic light-emitting diodes based on fluorescent blue emitters

    NASA Astrophysics Data System (ADS)

    Rosenow, Thomas C.; Furno, Mauro; Reineke, Sebastian; Olthof, Selina; Lüssem, Björn; Leo, Karl

    2010-12-01

    Beside inorganic LEDs and fluorescent lamps, organic light-emitting diodes (OLEDs) are evolving into a serious alternative to incandescent lamps. Up to now, it was assumed that all-phosphorescent OLEDs are required for reaching sufficiently high efficiencies. However, the stability of phosphorescent blue emitters is a major challenge. We present a novel approach to achieve highly efficient (up to 90 lm/W at 1000 cd/m2 using a macroextractor) white light emission from OLEDs. The here presented combination of a fluorescent blue and a phosphorescent red emitter simultaneously allows for a strong blue emission and efficient triplet transfer to the phosphor. The spectrum is extended in the green and yellow region by a full phosphorescent unit stacked on top of the triplet harvesting device. This superposition of four different emitters results in color coordinates close to illuminant A and a color rendering index of 80. Furthermore, color stability is given with respect to varying driving conditions and estimations of the electrical and optical efficiencies are provided.

  19. Intraoperative Localization of Insulinoma and Normal Pancreas using Invisible Near-Infrared Fluorescent Light

    PubMed Central

    Winer, Joshua; Choi, Hak Soo; Gibbs-Strauss, Summer L.; Ashitate, Yoshitomo; Colson, Yolonda L.; Frangioni, John V.

    2009-01-01

    Background: Neuroendocrine tumors of the pancreas, such as insulinoma, are difficult to localize and complete resection is essential for cure. Our hypothesis is that a near-infrared (NIR) fluorophore exhibiting uptake in insulinoma could provide high sensitivity detection intraoperatively. Methods: The optical properties of methylene blue (MB) were measured in vitro in 100% serum at 37°C, and in vivo after tissue uptake. MB was injected as a rapid intravenous bolus at doses ranging from 0.25 to 2 mg/kg into wildtype rats and pigs, and into insulinoma-bearing transgenic mice. The FLARE™ imaging system was used to acquire color video and NIR fluorescence images simultaneously, and in real-time. The signal-to-background ratios (SBR) of tissues and tumors were quantified using FLARE™ software. Results: When appropriately diluted, MB exhibits moderate NIR fluorescence emission peaking at 688 nm. At doses ≥ 1 mg/kg, certain normal tissues, such as pancreas, accumulate MB and remain NIR fluorescent for up to 1 hr with an SBR ≥ 1.6. MB spectral properties are maintained after uptake into tissue. Interestingly, insulinoma exhibits even higher uptake for MB than normal pancreas, resulting in insulinoma-to-pancreas ratios of 3.7 and insulinoma-to-muscle ratios of 16.2. MB permitted high-sensitivity, real-time localization of primary, multi-centric, and metastatic insulinoma, and permitted differentiation among tumor, normal pancreas, and other abdominal structures. Conclusion: A single intravenous injection of a clinically available, commonly used NIR fluorophore provides prolonged intraoperative localization of normal pancreas and insulinoma using invisible NIR fluorescent light. PMID:20033320

  20. Air fluorescence measurements in the spectral range 300 420 nm using a 28.5 GeV electron beam

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abu-Zayyad, T.; Belov, K.; Belz, J.; Cao, Z.; Dalton, M.; Fedorova, Y.; Hüntemeyer, P.; Jones, B. F.; Jui, C. C. H.; Loh, E. C.; Manago, N.; Martens, K.; Matthews, J. N.; Maestas, M.; Rodriguez, D.; Smith, J.; Sokolsky, P.; Springer, R. W.; Thomas, J.; Thomas, S.; Chen, P.; Field, C.; Hast, C.; Iverson, R.; Ng, J. S. T.; Odian, A.; Reil, K.; Walz, D.; Bergman, D. R.; Thomson, G.; Zech, A.; Chang, F.-Y.; Chen, C.-C.; Chen, C.-W.; Huang, M. A.; Hwang, W.-Y. P.; Lin, G.-L.

    2008-02-01

    Measurements are reported of the yield and spectrum of fluorescence, excited by a 28.5 GeV electron beam, in air at a range of pressures of interest to ultra-high energy cosmic ray detectors. The wavelength range was 300 420 nm. System calibration has been performed using Rayleigh scattering of a nitrogen laser beam. In atmospheric pressure dry air at 304 K the total yield is 20.8 ± 1.6 photons per MeV.

  1. Light-Induced Conformational Changes of Rhodopsin Probed by Fluorescent Alexa594 Immobilized on the Cytoplasmic Surface†

    PubMed Central

    Imamoto, Yasushi; Kataoka, Mikio; Tokunaga, Fumio; Palczewski, Krzysztof

    2006-01-01

    A novel fluorescence method has been developed for detecting the light-induced conformational changes of rhodopsin and for monitoring the interaction between photolyzed rhodopsin and G-protein or arrestin. Rhodopsin in native membranes was selectively modified with fluorescent Alexa594–maleimide at the Cys316 position, with a large excess of the reagent Cys140 that was also derivatized. Modification with Alexa594 allowed the monitoring of fluorescence changes at a red excitation light wavelength of 605 nm, thus avoiding significant rhodopsin bleaching. Upon absorption of a photon by rhodopsin, the fluorescence intensity increased as much as 20% at acidic pH with an apparent pKa of ∼6.8 at 4 °C, and was sensitive to the presence of hydroxylamine. These findings indicated that the increase in fluorescence is specific for metarhodopsin II. In the presence of transducin, a significant increase in fluorescence was observed. This increase of fluorescence emission intensity was reduced by addition of GTP, in agreement with the fact that transducin enhances the formation of metarhodopsin II. Under conditions that favored the formation of a metarhodopsin II–Alexa594 complex, transducin slightly decreased the fluorescence. In the presence of arrestin, under conditions that favored the formation of metarhodopsin I or II, a phosphorylated, photolyzed rhodopsin–Alexa594 complex only slightly decreased the fluorescence intensity, suggesting that the cytoplasmic surface structure of metarhodopsin II is different in the complex with arrestin and transducin. These results demonstrate the application of Alexa594-modified rhodopsin (Alexa594–rhodopsin) to continuously monitor the conformational changes in rhodopsin during light-induced transformations and its interactions with other proteins. PMID:11106502

  2. Acceptability testing of radioluminescent lights for VFR-night air taxi operations

    SciTech Connect

    Jensen, G.A.

    1985-01-01

    Tritium-powered radioluminescent (RL) lights have been under development for remote, austere, and tactical airfield lighting applications. The State of Alaska has requested FAA approval for use of the technology as a safe alternative lighting system to meet the airfield lighting needs of air taxi operations and general aviation in the state. The tests described in this report were performed by PNL for the DOE Defense Byproducts Production and Utilization Program. These tests are a step toward gaining the required approvals.

  3. Developing methods based on light sheet fluorescence microscopy for biophysical investigations of larval zebrafish

    NASA Astrophysics Data System (ADS)

    Taormina, Michael J.

    Adapting the tools of optical microscopy to the large-scale dynamic systems encountered in the development of multicellular organisms provides a path toward understanding the physical processes necessary for complex life to form and function. Obtaining quantitatively meaningful results from such systems has been challenging due to difficulty spanning the spatial and temporal scales representative of the whole, while also observing the many individual members from which complex and collective behavior emerges. A three-dimensional imaging technique known as light sheet fluorescence microscopy provides a number of significant benefits for surmounting these challenges and studying developmental systems. A thin plane of fluorescence excitation light is produced such that it coincides with the focal plane of an imaging system, providing rapid acquisition of optically sectioned images that can be used to construct a three-dimensional rendition of a sample. I discuss the implementation of this technique for use in larva of the model vertebrate Danio rerio (zebrafish). The nature of light sheet imaging makes it especially well suited to the study of large systems while maintaining good spatial resolution and minimizing damage to the specimen from excessive exposure to excitation light. I show the results from a comparative study that demonstrates the ability to image certain developmental processes non-destructively, while in contrast confocal microscopy results in abnormal growth due to phototoxicity. I develop the application of light sheet microscopy to the study of a previously inaccessible system: the bacterial colonization of a host organism. Using the technique, we are able to obtain a survey of the intestinal tract of a larval zebrafish and observe the location of microbes as they grow and establish a stable population in an initially germ free fish. Finally, I describe a new technique to measure the fluid viscosity of this intestinal environment in vivo using

  4. Analysis of air quality and nighttime light for Indian urban regions

    NASA Astrophysics Data System (ADS)

    Misra, Prakhar; Takeuchi, Wataru

    2016-06-01

    Indian urban regions suffer severe air pollution issues. A 2014 study by WHO highlighted that out of 20 cities globally with worst air quality, 13 lie in India. Although insufficient ground monitoring data and incomplete air pollution source characterization impedes putting policy measures to tackle this issue, remote sensing and GIS can overcome this hurdle to some extent. To find out how much of this hazard is due to economic growth, past researches have tried to make use of socio-economic growth indicators like GDP, population or urban area to establish its correlation with air quality in urban centres. Since nightlight has been found to correlate well with economic conditions at national and city level, an attempt has been made to analyse it with air quality levels to find regions with high contribution of anthropogenic emissions. Nighttime light activity was observed through DayNight Band (DNB) of VIIRS sensor while the air quality levels were obtained for ANG and AOD (using MODIS sensor) and SO2 and NO2 (using OMI sensor). We have classified Indian landmass into 4 air-quality and DNB classes: LowLight- HighPollution, HighLight-HighPollution, LowLight-LowPollution and HighLight- LowPollution for each air quality species using June 2014 data. It was found that around half of urban regions show high AOD and ANG values. On the other hand almost all urban regions exhibit high SO2 and NO2 values.

  5. Light pollution from the ground, the air and the space

    NASA Astrophysics Data System (ADS)

    Sánchez de Miguel, A.; Zamorano, J.; Gómez Castaño, J.; Aubé, M.; Bará, S.; Gallego, J.; Kyba, C. C. M.; Lombraña, D.; Nievas, M.; Pascual, S.; Tapia, C.

    2015-05-01

    The sky brightness is one of the things that most harms astronomical observation, near cities and on mountain observatories. Currently there are several initiatives to control light pollution, but the sky brightness measurements are usually local. To exercise adequate control of light pollution is necessary measurements of light pollution sources and their relation to the spatiotemporal variation of the sky brightness. We use various approaches: data taken ashore with photometers SQM and relate emissions and detected with VIIRS and DMSP satellites. We also use multispectral data taken from the International Space Station to distinguish different types of lamps that contribute to light pollution. Finally we used a spectrograph SAND for temporal analysis of the evolution of the contribution of the lights in the sky brightness of a big city like Madrid. Also we have performed a citizen science program to classify the night time images taken from the ISS (Sánchez de Miguel et al. 2014, A&G, 55, 4, 36).

  6. Energy transfer and light tolerance studies in a fluorescent tandem phycobiliprotein conjugate.

    PubMed

    Tian, Yu; Pappas, Dimitri

    2011-09-01

    Light harvesting and energy transfer between allophycocyanin (APC) and a tandem conjugate dye was investigated using single-molecule recrossings in the probe volume. By comparing saturation irradiance and recrossing events of APC and the tandem conjugate Streptavidin Allophycocyanin-AlexaFluor-680 (APC-680), it was demonstrated that the light tolerance and photostability of APC-680 were improved over APC. This improvement was due to conjugating a tandem dye to APC, which provided an alternative pathway for energy transfer. This additional pathway decreases photobleaching and triplet-state conversion. In this study, the average fluorescence intensity at different laser powers was calculated from extracted signal peaks. Saturation irradiance was determined by interpolating the average intensity as a function of excitation power. By comparing the saturation irradiance of APC and APC-680, it was demonstrated that light tolerance was not significantly increased by having a small fluorophore covalently linked to the protein. The molecular recrossing method was used to determine triplet-state conversion and photobleaching effects. The number of molecules that were detected within 2 ms of each other was defined as the number of recrossing events (N(r)). The total number of molecules detected was defined as N(t). The normalized number of recrossings events (N(r)/N(t)) showed that energy transfer between APC and AlexaFluor-680 could reduce triplet-state formation of phycobiliproteins. In this case, the saturation irradiance was not improved, but the resistance to photobleaching and triplet-state conversion was improved. PMID:21929852

  7. Highly Efficient Sky-Blue Fluorescent Organic Light Emitting Diode Based on Mixed Cohost System for Thermally Activated Delayed Fluorescence Emitter (2CzPN).

    PubMed

    Sun, Jin Won; Kim, Kwon-Hyeon; Moon, Chang-Ki; Lee, Jeong-Hwan; Kim, Jang-Joo

    2016-04-20

    The mixed cohosts of 1,3-bis(N-carbazolyl)benzene and 2,8-bis(diphenylphosphoryl)dibenzothiophene have been developed for a highly efficient blue fluorescent oragnic light emitting diode (OLED) doped with a thermally activated delayed fluorescence (TADF) emitter [4,5-di (9H-carbazol-9-yl) phthalonitrile (2CzPN)]. We have demonstrated one of the highest external quantum efficiency of 21.8% in blue fluorescent OLEDs, which is identical to the theoretically achievable maximum electroluminescence efficiency using the emitter. Interestingly, the efficiency roll-off is large even under the excellent charge balance in the device and almost the same as the single host based devices, indicating that the efficiency roll-off in 2CzPN based TADF host is related to the material characteristics, such as low reverse intesystem crossing rate rather than charge imbalance. PMID:27019330

  8. Light-Emitting Diodes and Cool White Fluorescent Light Similarly Suppress Pineal Gland Melatonin and Maintain Retinal Function and Morphology in the Rat. Part 1

    NASA Technical Reports Server (NTRS)

    Holley, Daniel C.; Heeke, D.; Mele, G.

    1999-01-01

    Currently, the light sources most commonly used in animal habitat lighting are cool white fluorescent or incandescent lamps. We evaluated a novel light-emitting diode (LED) light source for use in animal habitat lighting by comparing its effectiveness to cool white fluorescent light (CWF) in suppressing pineal gland melatonin and maintaining normal retinal physiology and morphology in the rat. Results of pineal melatonin suppression experiments showed equal suppression of pineal melatonin concentrations for LED light and CWF light at five different light illuminances (100, 40, 10, 1 and 0.1 lux). There were no significant differences in melatonin suppression between LED and CWF light when compared to unexposed controls. Retinal physiology was evaluated using electroretinography. Results show no differences in a-wave implicit times and amplitudes or b-wave implicit times and amplitudes between 100-lux LED-exposed rats and 100-lux CWF-exposed rats. Results of retinal histology assessment show no differences in retinal thickness rod outer segment length and number of rod nuclei between rats exposed to 100-lux LED and 100-lux CWF for days. Furthermore, the retinal pigmented epithelium and rod outer segments of all eyes observed were in good condition and of normal thickness. This study indicates that LED light does not cause retinal damage and can suppress pineal melatonin at similar intensities as a conventional CWF light source. These data suggest that LED light sources may be suitable replacements for conventional light sources used in the lighting of rodent vivariums while providing many mechanical and economical advantages.

  9. epi-Fluorescence imaging at the air-water interface of fibrillization of bovine serum albumin and human insulin.

    PubMed

    Sessions, Kristen; Sacks, Stuart; Li, Shanghao; Leblanc, Roger M

    2014-08-18

    Protein fibrillization is associated with many devastating neurodegenerative diseases. This process has been studied using spectroscopic and microscopic methods. In this study, epi-fluorescence at the air-water interface was developed as an innovative technique for observing fibrillization of bovine serum albumin and human insulin. PMID:24976597

  10. Efficient near-infrared organic light-emitting devices based on low-gap fluorescent oligomers

    NASA Astrophysics Data System (ADS)

    Yang, Yixing; Farley, Richard T.; Steckler, Timothy T.; Eom, Sang-Hyun; Reynolds, John R.; Schanze, Kirk S.; Xue, Jiangeng

    2009-08-01

    We report efficient near-infrared (NIR) organic light-emitting devices (OLEDs) based on fluorescent donor-acceptor-donor conjugated oligomers. The energies of the highest occupied and lowest unoccupied molecular orbitals of these oligomers are controlled by the donor and acceptor components, respectively; hence the energy gap and therefore the emission wavelength can be tuned by changing the strengths of the donor and acceptor components. External quantum efficiencies (EQEs) up to 1.6% and power efficiencies up to 7.0 mW/W are achieved in NIR OLEDs based on 4,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-6,7-dimethyl-[1,2,5]thiadiazolo[3,4-g]-quinoxaline (BEDOT-TQMe2), in which the electroluminescence peaks at a wavelength of 692 nm but extends to well above 800 nm. With a stronger acceptor in the oligomer, 4,8-bis(2,3-dihydrothieno-[3,4-b][1,4]dioxin-5-yl)benzo[1,2-c;4,5-c']bis [1,2,5]thiadiazole (BEDOT-BBT) based devices show longer wavelength emission peaked at 815 nm, although the maximum EQE is reduced to 0.51% due to the lower fluorescent quantum yield of the NIR emitter. The efficiencies of these NIR OLEDs are further increased by two to three times by using the sensitized fluorescent device structure, leading to a maximum EQE of 3.1% for BEDOT-TQMe2 and 1.6% for BEDOT-BBT based devices.

  11. UV-Light-Induced Improvement of Fluorescence Quantum Yield of DNA-Templated Gold Nanoclusters: Application to Ratiometric Fluorescent Sensing of Nucleic Acids.

    PubMed

    Li, Zong-Yu; Wu, Yun-Tse; Tseng, Wei-Lung

    2015-10-28

    The use of DNA as a template has been demonstrated as an effective method for synthesizing different-sized silver nanoclusters. Although DNA-templated silver nanoclusters show outstanding performance as fluorescent probes for chemical sensing and cellular imaging, the synthesis of DNA-stabilized gold nanoclusters (AuNCs) with high fluorescence intensity remains a challenge. Here a facile, reproducible, scalable, NaBH4-free, UV-light-assisted method was developed to prepare AuNCs using repeats of 30 adenosine nucleotides (A30). The maximal fluorescence of A30-stabilized AuNCs appeared at 475 nm with moderate quantum yield, two fluorescence lifetimes, and a small amount of Au(+) on the surface of the Au core. Results of size-exclusion chromatography revealed that A30-stabilized AuNCs were more compact than A30. A series of control experiments showed that UV light played a dual role in the reduction of gold-ion precursors and the decomposition of citrate ions. A30 also acted as a stabilizer to prevent the aggregation of AuNCs. In addition, single-stranded DNA (ssDNA) consisting of an AuNC-nucleation sequence and a hybridization sequence was utilized to develop a AuNC-based ratiometric fluorescent probe in the presence of the double-strand-chelating dye SYBR Green I (SG). Under conditions of single-wavelength excitation, the combination of AuNC/SG-bearing ssDNA and perfectly matched DNA emitted fluorescence at 475 and 525 nm, respectively. The formed AuNC/SG-bearing ssDNA enabled the sensitive, selective, and ratiometric detection of specific nucleic acid targets. Finally, the AuNC-based ratiometric probes were successfully applied to determine specific nucleic acid targets in human serum. PMID:26443919

  12. Polarized fluorescence and absorption of macroscopically aligned Light Harvesting Complex II.

    PubMed Central

    van Amerongen, H; Kwa, S L; van Bolhuis, B M; van Grondelle, R

    1994-01-01

    Polarized absorption and fluorescence measurements have been performed at 77 K on isotropic and anisotropic preparations of trimeric Light Harvesting Complex II (LHC-II) from spinach. The results enable a decomposition of the absorption spectrum into components parallel and perpendicular to the trimeric plane. For the first time, it is shown quantitatively that the strong absorption band around 676 nm is polarized essentially parallel to the plane of the trimer, i.e., the average angle between the corresponding transition dipole moments and this plane is at most 12 degrees. The different absorption bands for LHC-II should not be considered as corresponding to individual pigments but to collective excitations of different pigments. Nevertheless, the average angle between the Qy transition dipole moments of all chlorophyll a pigments in LHC-II and the trimeric plane could be determined and was found to be 17.5 degrees +/- 2.5 degrees. For the chlorophyll b pigments, this angle is significantly larger (close to 35 degrees). At 77 K, most of the fluorescence stems from a weak band above 676 nm and the corresponding transition dipole moments are oriented further out of plane than the dipole moments corresponding to the 676-nm band. The results are shown to be of crucial significance for understanding the relation between the LHC-II structure and its spectroscopy. PMID:7948696

  13. Eyecup scope—optical recordings of light stimulus-evoked fluorescence signals in the retina

    PubMed Central

    Hausselt, Susanne E.; Breuninger, Tobias; Castell, Xavier; Denk, Winfried; Margolis, David J.; Detwiler, Peter B.

    2009-01-01

    Dendritic signals play an essential role in processing visual information in the retina. To study them in neurites too small for electrical recording, we developed an instrument that combines a multi-photon (MP) microscope with a through-the-objective high-resolution visual stimulator. An upright microscope was designed that uses the objective lens for both MP imaging and delivery of visual stimuli to functionally intact retinal explants or eyecup preparations. The stimulator consists of a miniature liquid-crystal-on-silicon display coupled into the optical path of an infrared-excitation laser-scanning microscope. A pair of custom-made dichroic filters allows light from the excitation laser and three spectral bands (‘colors’) from the stimulator to reach the retina, leaving two intermediate bands for fluorescence imaging. Special optics allow displacement of the stimulator focus relative to the imaging focus. Spatially resolved changes in calcium-indicator fluorescence in response to visual stimuli were recorded in dendrites of different types of mammalian retinal neurons. PMID:19023590

  14. Iron oxide nanozyme catalyzed synthesis of fluorescent polydopamine for light-up Zn(2+) detection.

    PubMed

    Liu, Biwu; Han, Xiao; Liu, Juewen

    2016-07-14

    Fluorescent polydopamine (FPD) is an interesting material with excellent biocompatibility. However, its preparation is currently a lengthy and potentially dangerous process. We herein employ magnetic iron oxide (Fe3O4) nanoparticles as a peroxidase-mimicking nanozyme to produce FPD under mild conditions. Different from previous protocols using multiple steps with up to 6% (∼2 M) H2O2, this preparation takes place in a single step with just 5 mM H2O2 at room temperature. The oxidized product shows excitation-wavelength-dependent emission peaks, similar to previous reports. The reaction kinetics, pH, temperature, and ionic strength are individually optimized. Among a diverse range of other nanomaterials tested, including Fe2O3, CeO2, CoO, Co3O4, NiO, TiO2, gold nanoparticles, and graphene oxide, Fe2O3 and graphene oxide yielded relatively weak emission, while the rest of the materials failed to produce FPD. The Fe3O4 nanoparticles retained ∼90% catalytic activity even after ten cycles of synthesis. Finally, Zn(2+) can enhance the fluorescence of FPD under 360 nm excitation but not under 480 nm excitation, leading to a sensitive light-up sensor with a detection limit of 60 nM Zn(2+). Therefore, this work has demonstrated not only a novel use of nanozymes, but also an interesting application of FPD. PMID:27364882

  15. Robust incremental compensation of the light attenuation with depth in 3D fluorescence microscopy.

    PubMed

    Kervrann, C; Legland, D; Pardini, L

    2004-06-01

    Summary Fluorescent signal intensities from confocal laser scanning microscopes (CLSM) suffer from several distortions inherent to the method. Namely, layers which lie deeper within the specimen are relatively dark due to absorption and scattering of both excitation and fluorescent light, photobleaching and/or other factors. Because of these effects, a quantitative analysis of images is not always possible without correction. Under certain assumptions, the decay of intensities can be estimated and used for a partial depth intensity correction. In this paper we propose an original robust incremental method for compensating the attenuation of intensity signals. Most previous correction methods are more or less empirical and based on fitting a decreasing parametric function to the section mean intensity curve computed by summing all pixel values in each section. The fitted curve is then used for the calculation of correction factors for each section and a new compensated sections series is computed. However, these methods do not perfectly correct the images. Hence, the algorithm we propose for the automatic correction of intensities relies on robust estimation, which automatically ignores pixels where measurements deviate from the decay model. It is based on techniques adopted from the computer vision literature for image motion estimation. The resulting algorithm is used to correct volumes acquired in CLSM. An implementation of such a restoration filter is discussed and examples of successful restorations are given. PMID:15157197

  16. Light-emitting diode and laser fluorescence-based devices in detecting occlusal caries

    NASA Astrophysics Data System (ADS)

    Rodrigues, Jonas A.; Hug, Isabel; Neuhaus, Klaus W.; Lussi, Adrian

    2011-10-01

    The aim of this study was to assess the performance of two light-emitting diode (LED)- and two laser fluorescence-based devices in detecting occlusal caries in vitro. Ninety-seven permanent molars were assessed twice by two examiners using two LED- (Midwest Caries - MID and VistaProof - VP) and two laser fluorescence-based (DIAGNOdent 2095 - LF and DIAGNOdent pen 2190 - LFpen) devices. After measuring, the teeth were histologically prepared and classified according to lesion extension. At D1 the specificities were 0.76 (LF and LFpen), 0.94 (MID), and 0.70 (VP); the sensitivities were 0.70 (LF), 0.62 (LFpen), 0.31 (MID), and 0.75 (VP). At D3 threshold the specificities were 0.88 (LF), 0.87 (LFpen), 0.90 (MID), and 0.70 (VP); the sensitivities were 0.63 (LF and LFpen), 0.70 (MID), and 0.96 (VP). Spearman's rank correlations with histology were 0.56 (LF), 0.51 (LFpen), 0.55 (MID), and 0.58 (VP). Inter- and intraexaminer ICC values were high and varied from 0.83 to 0.90. Both LF devices seemed to be useful auxiliary tools to the conventional methods, presenting good reproducibility and better accuracy at D3 threshold. MID was not able to differentiate sound surfaces from enamel caries and VP still needs improvement on the cut-off limits for its use.

  17. Above 30% external quantum efficiency in green delayed fluorescent organic light-emitting diodes.

    PubMed

    Lee, Dong Ryun; Kim, Bo Seong; Lee, Chil Won; Im, Yirang; Yook, Kyoung Soo; Hwang, Seok-Ho; Lee, Jun Yeob

    2015-05-13

    Highly efficient green thermally activated delayed fluorescent organic light-emitting diodes with an external quantum efficiency of 31.2% were investigated by using 3-(3-(carbazole-9-yl)phenyl) pyrido[3',2':4,5]furo[2,3-b]pyridine (3CzPFP) derived from carbazole and pyrido[3',2':4,5]furo[2,3-b]pyridine. The host material showed well-matched photoluminescence emission with absorption of the green dopant material, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) and harvested all excitons of 4CzIPN. The 3CzPFP:4CzIPN film exhibited high photoluminescence quantum yield of 100%, and the green delayed fluorescence device employing the 3CzPFP host showed high maximum quantum efficiency of 31.2 ± 0.5% at 1% doping after optimization of the device structure. PMID:25924007

  18. Combined application of dynamic light scattering imaging and fluorescence intravital microscopy in vascular biology

    NASA Astrophysics Data System (ADS)

    Kalchenko, V.; Ziv, K.; Addadi, Y.; Madar-Balakirski, N.; Meglinski, I.; Neeman, M.; Harmelin, A.

    2010-08-01

    The dynamic light scattering imaging (DLSI) system combined with the conventional fluorescence intravital microscope (FIM) has been applied for the examination of blood and lymph vessels in the mouse ear in vivo. While the CCD camera can be shared by both techniques the combined application of DLSI and FIM allows rapid switching between the modalities. In current study temporal speckles fluctuations are used for rendering blood vessels structure and monitoring blood perfusion with the higher spatial resolution, whereas FIM provides the images of lymphatic vessels. The results clearly demonstrate that combined application of DLSI and FIM approaches provides synchronic in vivo images of blood and lymph vessels with higher contrast and specificity. The use of this new dual-modal diagnostic system is particularly important and has a great potential to significantly expand the capabilities of vascular diagnostics providing synchronic in vivo images of blood and lymph vessels.

  19. Triarylboron-Based Fluorescent Organic Light-Emitting Diodes with External Quantum Efficiencies Exceeding 20 .

    PubMed

    Suzuki, Katsuaki; Kubo, Shosei; Shizu, Katsuyuki; Fukushima, Tatsuya; Wakamiya, Atsushi; Murata, Yasujiro; Adachi, Chihaya; Kaji, Hironori

    2015-12-01

    Triarylboron compounds have attracted much attention, and found wide use as functional materials because of their electron-accepting properties arising from the vacant p orbitals on the boron atoms. In this study, we design and synthesize new donor-acceptor triarylboron emitters that show thermally activated delayed fluorescence. These emitters display sky-blue to green emission and high photoluminescence quantum yields of 87-100 % in host matrices. Organic light-emitting diodes using these emitting molecules as dopants exhibit high external quantum efficiencies of 14.0-22.8 %, which originate from efficient up-conversion from triplet to singlet states and subsequent efficient radiative decay from singlet to ground states. PMID:26563845

  20. A wide field fluorescence lifetime imaging system using a light sheet microscope

    NASA Astrophysics Data System (ADS)

    Birch, Phil M.; Moore, Lamar; Li, Xiaofei; Phillips, Roger; Young, Rupert; Chatwin, Chris

    2016-04-01

    Fluorescence lifetime imaging microscopy (FLIM) has allowed scientists to discern information about the chemical properties of biological processes and has become a vital tool in the life sciences and medical research communities. Measuring the spatial lifetime distribution of the fluorophores as well as the intensity distribution enables users to discern vital information about the chemical environment. It however, remains challenging and often involves slow scanning. We present a new microscope system based on light sheet illumination that uses a micro channel plate (MCP) device called a Capacitive Division Imaging Readout (CDIR) which has been developed by Photek Ltd. The device uses an array of capacitors to move the charge site from the MCP to four pre-amplifiers and time-over-threshold discriminators. This camera has the ability to image photons as well as measure the arrival time, enabling high speed FLIM imaging of biological samples.

  1. High-efficiency fluorescent organic light-emitting diodes enabled by triplet-triplet annihilation and horizontal emitter orientation

    SciTech Connect

    Mayr, Christian Schmidt, Tobias D.; Brütting, Wolfgang

    2014-11-03

    A green organic light-emitting diode with the fluorescent emitter Coumarin 545T shows an external quantum efficiency (η{sub EQE}) of 6.9%, clearly exceeding the classical limit of 5% for fluorescent emitters. The analysis of the angular dependent photoluminescence spectrum of the emission layer reveals that 86% of the transition dipole moments are horizontally oriented. Furthermore, transient electroluminescence measurements demonstrate the presence of a delayed emission originating from triplet-triplet annihilation. A simulation based efficiency analysis reveals quantitatively the origin for the high η{sub EQE}: a radiative exciton fraction higher than 25% and a light-outcoupling efficiency of nearly 30%.

  2. Visible Light Responsive Catalyst for Air Water Purification Project

    NASA Technical Reports Server (NTRS)

    Wheeler, Raymond M.

    2014-01-01

    Investigate and develop viable approaches to render the normally UV-activated TIO2 catalyst visible light responsive (VLR) and achieve high and sustaining catalytic activity under the visible region of the solar spectrum.

  3. Protein oxidative changes in whole and skim milk after ultraviolet or fluorescent light exposure.

    PubMed

    Scheidegger, D; Pecora, R P; Radici, P M; Kivatinitz, S C

    2010-11-01

    We investigated how protein changes occur, at the primary or higher structural levels, when proteins are exposed to UV or fluorescent (FL) light while in the complex matrix, milk. Whole milk (WM) or skim milk (SM) samples were exposed to FL or UV light from 0 to 24h at 4°C. Protein oxidation was evaluated by the formation of protein carbonyls (PC), dityrosine bond (DiTyr), and changes in molecular weight (protein fragmentation and polymerization). Oxidative changes in AA residues were measured by PC. Dityrosine and N'-formylkynurenine (NFK), a carbonylation derivative of Trp, were measured by fluorometry. Protein carbonyls increased as a function of irradiation time for both WM and SM. The initial rate for PC formation by exposure to FL light (0.25 or 0.27 nmol/h for WM and SM, respectively) was slower than that following exposure to UV light (1.95 or 1.20 nmol/h, respectively). The time course of NFK formation resembled that of PC. After 24h of UV exposure, SM had significantly higher levels of NFK than did WM. In contrast, WM samples irradiated with UV had higher levels of DiTyr than did SM samples, indicating different molecular pathways. The formation of intra- or intermolecular DiTyr bonds could be indicative of changes in the tertiary structure or oligomerization of proteins. The existence of NFK suggests the occurrence of protein fragmentation. Thus, proteolysis and oligomerization were analyzed by sodium dodecyl sulfate-PAGE. After 24h of exposing WM to UV or FL light, all the proteins were affected by both types of light, as evidenced by loss of material in most of the bands. Aggregates were produced only by UV irradiation. Hydrolysis by pepsin and enzyme-induced coagulation by rennet were performed to evaluate altered biological properties of the oxidized proteins. No effect on pepsin digestion or rennet coagulation was found in irradiated SM or WM. The oxidative status of proteins in milk and dairy products is of interest to the dairy industry and

  4. Lighting energy efficiency opportunities at Cheyenne Mountain Air Station

    SciTech Connect

    Molburg, J.C.; Rozo, A.J.; Sarles, J.K.; Haffenden, R.A.; Thimmapuram, P.R.; Cavallo, J.D.

    1996-06-01

    CMAS is an intensive user of electricity for lighting because of its size, lack of daylight, and 24-hour operating schedule. Argonne National Laboratory recently conducted a lighting energy conservation evaluation at CMAS. The evaluation included inspection and characterization of existing lighting systems, analysis of energy-efficient retrofit options, and investigation of the environmental effects that these lighting system retrofits could have when they are ready to be disposed of as waste. Argonne devised three retrofit options for the existing lighting systems at various buildings: (1) minimal retrofit--limited fixture replacement; (2) moderate retrofit--more extensive fixture replacement and limited application of motion detectors; and (3) advanced retrofit--fixture replacement, reduction in the number of lamps, expansion of task lighting, and more extensive application of motion detectors. Argonne used data on electricity consumption to analyze the economic and energy effects of these three retrofit options. It performed a cost analysis for each retrofit option in terms of payback. The analysis showed that lighting retrofits result in savings because they reduce electricity consumption, cooling load, and maintenance costs. The payback period for all retrofit options was found to be less than 2 years, with the payback period decreasing for more aggressive retrofits. These short payback periods derived largely from the intensive (24-hours-per-day) use of electric lighting at the facility. Maintenance savings accounted for more than half of the annual energy-related savings under the minimal and moderate retrofit options and slightly less than half of these savings under the advanced retrofit option. Even if maintenance savings were excluded, the payback periods would still be impressive: about 4.4 years for the minimal retrofit option and 2 years for the advanced option. The local and regional environmental impacts of the three retrofit options were minimal.

  5. Comparing phototoxicity during the development of a zebrafish craniofacial bone using confocal and light sheet fluorescence microscopy techniques

    PubMed Central

    Jemielita, Matthew; Taormina, Michael J.; DeLaurier, April; Kimmel, Charles B.; Parthasarathy, Raghuveer

    2013-01-01

    The combination of genetically encoded fluorescent proteins and three-dimensional imaging enables cell-type-specific studies of embryogenesis. Light sheet microscopy, in which fluorescence excitation is provided by a plane of laser light, is an appealing approach to live imaging due to its high speed and efficient use of photons. While the advantages of rapid imaging are apparent from recent work, the importance of low light levels to studies of development is not well established. We examine the zebrafish opercle, a craniofacial bone that exhibits pronounced shape changes at early developmental stages, using both spinning disk confocal and light sheet microscopies of fluorescent osteoblast cells. We find normal and aberrant opercle morphologies for specimens imaged with short time intervals using light sheet and spinning disk confocal microscopies, respectively, under equivalent exposure conditions over developmentally-relevant time scales. Quantification of shapes reveals that the differently imaged specimens travel along distinct trajectories in morphological space. (A) Schematic: Light sheet microscopy of zebrafish embryos. Opercle-forming osteoblasts following twenty-four hours of (B) light sheet imaging, showing normal growth, and (C) spinning disk confocal imaging, showing aberrant growth. PMID:23242824

  6. Iron oxide nanozyme catalyzed synthesis of fluorescent polydopamine for light-up Zn2+ detection

    NASA Astrophysics Data System (ADS)

    Liu, Biwu; Han, Xiao; Liu, Juewen

    2016-07-01

    Fluorescent polydopamine (FPD) is an interesting material with excellent biocompatibility. However, its preparation is currently a lengthy and potentially dangerous process. We herein employ magnetic iron oxide (Fe3O4) nanoparticles as a peroxidase-mimicking nanozyme to produce FPD under mild conditions. Different from previous protocols using multiple steps with up to 6% (~2 M) H2O2, this preparation takes place in a single step with just 5 mM H2O2 at room temperature. The oxidized product shows excitation-wavelength-dependent emission peaks, similar to previous reports. The reaction kinetics, pH, temperature, and ionic strength are individually optimized. Among a diverse range of other nanomaterials tested, including Fe2O3, CeO2, CoO, Co3O4, NiO, TiO2, gold nanoparticles, and graphene oxide, Fe2O3 and graphene oxide yielded relatively weak emission, while the rest of the materials failed to produce FPD. The Fe3O4 nanoparticles retained ~90% catalytic activity even after ten cycles of synthesis. Finally, Zn2+ can enhance the fluorescence of FPD under 360 nm excitation but not under 480 nm excitation, leading to a sensitive light-up sensor with a detection limit of 60 nM Zn2+. Therefore, this work has demonstrated not only a novel use of nanozymes, but also an interesting application of FPD.Fluorescent polydopamine (FPD) is an interesting material with excellent biocompatibility. However, its preparation is currently a lengthy and potentially dangerous process. We herein employ magnetic iron oxide (Fe3O4) nanoparticles as a peroxidase-mimicking nanozyme to produce FPD under mild conditions. Different from previous protocols using multiple steps with up to 6% (~2 M) H2O2, this preparation takes place in a single step with just 5 mM H2O2 at room temperature. The oxidized product shows excitation-wavelength-dependent emission peaks, similar to previous reports. The reaction kinetics, pH, temperature, and ionic strength are individually optimized. Among a diverse range

  7. Low-frequency wide-field fluorescence lifetime imaging using a high-power near-infrared light-emitting diode light source

    NASA Astrophysics Data System (ADS)

    Gioux, Sylvain; Lomnes, Stephen J.; Choi, Hak Soo; Frangioni, John V.

    2010-03-01

    Fluorescence lifetime imaging (FLi) could potentially improve exogenous near-infrared (NIR) fluorescence imaging, because it offers the capability of discriminating a signal of interest from background, provides real-time monitoring of a chemical environment, and permits the use of several different fluorescent dyes having the same emission wavelength. We present a high-power, LED-based, NIR light source for the clinical translation of wide-field (larger than 5 cm in diameter) FLi at frequencies up to 35 MHz. Lifetime imaging of indocyanine green (ICG), IRDye 800-CW, and 3,3'-diethylthiatricarbocyanine iodide (DTTCI) was performed over a large field of view (10 cm by 7.5 cm) using the LED light source. For comparison, a laser diode light source was employed as a gold standard. Experiments were performed both on the bench by diluting the fluorescent dyes in various chemical environments in Eppendorf tubes, and in vivo by injecting the fluorescent dyes mixed in Matrigel subcutaneously into CD-1 mice. Last, measured fluorescence lifetimes obtained using the LED and the laser diode sources were compared with those obtained using a state-of-the-art time-domain imaging system and with those previously described in the literature. On average, lifetime values obtained using the LED and the laser diode light sources were consistent, exhibiting a mean difference of 3% from the expected values and a coefficient of variation of 12%. Taken together, our study offers an alternative to laser diodes for clinical translation of FLi and explores the use of relatively low frequency modulation for in vivo imaging.

  8. Laser sheet light flow visualization for evaluating room air flowsfrom Registers

    SciTech Connect

    Walker, Iain S.; Claret, Valerie; Smith, Brian

    2006-04-01

    of a room in which whole-field supply air mixing maps of two vertical planes were measured using a Planar Laser-Induced Fluorescence (PLIF) measurement technique. Water marked with fluorescent dye was used to simulate the supply airflow; and the resulting concentrations within the water filled model show how the supply air mixes with the room air and are an analog for temperature (for thermal loads) or fresh air (for ventilation). In addition to performing experiments over a range of flow rates, we also changed register locations and examined the effects for both heating and cooling operation by changing the water density (simulating air density changes due to temperature changes) using dissolved salt.

  9. Efficient stray-light suppression for resonance fluorescence in quantum dot micropillars using self-aligned metal apertures

    NASA Astrophysics Data System (ADS)

    Hopfmann, Caspar; Musiał, Anna; Maier, Sebastian; Emmerling, Monika; Schneider, Christian; Höfling, Sven; Kamp, Martin; Reitzenstein, Stephan

    2016-09-01

    Within this work we propose and demonstrate a technological approach to efficiently suppress excitation laser stray-light in resonance fluorescence experiments on quantum dot micropillars. To ensure efficient stray-light suppression, their fabrication process includes a planarization step and subsequent covering with a titanium mask to fabricate self-aligned apertures at the micropillar positions. These apertures aim to limit laser stray-light in the side-excitation vertical-detection configuration, while enabling detection of the optical signal through the top facet of the micropillars. The beneficial effects of these apertures are proven and quantitatively evaluated within a statistical study in which we determine and compare the stray-light suppression of 48 micropillars with and without metal apertures. Actual resonance fluorescence experiments on single quantum dots coupled to the cavity mode prove the relevance of the proposed approach and demonstrate that it will foster further studies on cavity quantum electrodynamics phenomena under coherent optical excitation.

  10. Light Scattering by Ice Crystals Containing Air Bubbles

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.

    2014-12-01

    The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.

  11. Fluorescent all-fiber light source based on micro-capillaries and on microstructured optical fibers terminated with a microbulb

    NASA Astrophysics Data System (ADS)

    Vladev, Veselin; Eftimov, Tinko; Bock, Wojtek

    2015-12-01

    An integrated fiber-optic fluorescent light source compatible with photonic-crystal and hollow-core fibers is presented in this paper. We have studied the dependence of the fluorescence spectra on the length of a micro-capillary filled with Rhodamine 6G dissolved in glycerin. As the capillary, we used a standard fiber-optic glass ferrule with two parallel holes having an inner diameter of 125 μm. One of the holes was filled with fluorescing solution, while an SMF-28 fiber polished at 45° with aluminum coating was placed in the second hole to serve as a pumping fiber. As the solution was pumped by continuous-wave laser light at 532 nm, the fluorescence was captured by a microstructured optical fiber immersed in the filled hole. To prevent the solution from penetrating into this receiving fiber, its end was capped by molten borosilicate glass forming a ball lens. Combining the spectra of several fluorescent organic dyes can create a broadband light source compatible with optical fibers that could be used for the development of compact photonic-crystal and hollow-core fiber sensors.

  12. Virtual unfolding of light sheet fluorescence microscopy dataset for quantitative analysis of the mouse intestine

    NASA Astrophysics Data System (ADS)

    Candeo, Alessia; Sana, Ilenia; Ferrari, Eleonora; Maiuri, Luigi; D'Andrea, Cosimo; Valentini, Gianluca; Bassi, Andrea

    2016-05-01

    Light sheet fluorescence microscopy has proven to be a powerful tool to image fixed and chemically cleared samples, providing in depth and high resolution reconstructions of intact mouse organs. We applied light sheet microscopy to image the mouse intestine. We found that large portions of the sample can be readily visualized, assessing the organ status and highlighting the presence of regions with impaired morphology. Yet, three-dimensional (3-D) sectioning of the intestine leads to a large dataset that produces unnecessary storage and processing overload. We developed a routine that extracts the relevant information from a large image stack and provides quantitative analysis of the intestine morphology. This result was achieved by a three step procedure consisting of: (1) virtually unfold the 3-D reconstruction of the intestine; (2) observe it layer-by-layer; and (3) identify distinct villi and statistically analyze multiple samples belonging to different intestinal regions. Even if the procedure has been developed for the murine intestine, most of the underlying concepts have a general applicability.

  13. Correlative and integrated light and electron microscopy of in-resin GFP fluorescence, used to localise diacylglycerol in mammalian cells.

    PubMed

    Peddie, Christopher J; Blight, Ken; Wilson, Emma; Melia, Charlotte; Marrison, Jo; Carzaniga, Raffaella; Domart, Marie-Charlotte; O'Toole, Peter; Larijani, Banafshe; Collinson, Lucy M

    2014-08-01

    Fluorescence microscopy of GFP-tagged proteins is a fundamental tool in cell biology, but without seeing the structure of the surrounding cellular space, functional information can be lost. Here we present a protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin with electron contrast to reveal cellular ultrastructure. Ultrathin in-resin fluorescence (IRF) sections were imaged simultaneously for fluorescence and electron signals in an integrated light and scanning electron microscope. We show, for the first time, that GFP is stable and active in resin sections in vacuo. We applied our protocol to study the subcellular localisation of diacylglycerol (DAG), a modulator of membrane morphology and membrane dynamics in nuclear envelope assembly. We show that DAG is localised to the nuclear envelope, nucleoplasmic reticulum and curved tips of the Golgi apparatus. With these developments, we demonstrate that integrated imaging is maturing into a powerful tool for accurate molecular localisation to structure. PMID:24637200

  14. Correlative and integrated light and electron microscopy of in-resin GFP fluorescence, used to localise diacylglycerol in mammalian cells

    PubMed Central

    Peddie, Christopher J.; Blight, Ken; Wilson, Emma; Melia, Charlotte; Marrison, Jo; Carzaniga, Raffaella; Domart, Marie-Charlotte; O׳Toole, Peter; Larijani, Banafshe; Collinson, Lucy M.

    2014-01-01

    Fluorescence microscopy of GFP-tagged proteins is a fundamental tool in cell biology, but without seeing the structure of the surrounding cellular space, functional information can be lost. Here we present a protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin with electron contrast to reveal cellular ultrastructure. Ultrathin in-resin fluorescence (IRF) sections were imaged simultaneously for fluorescence and electron signals in an integrated light and scanning electron microscope. We show, for the first time, that GFP is stable and active in resin sections in vacuo. We applied our protocol to study the subcellular localisation of diacylglycerol (DAG), a modulator of membrane morphology and membrane dynamics in nuclear envelope assembly. We show that DAG is localised to the nuclear envelope, nucleoplasmic reticulum and curved tips of the Golgi apparatus. With these developments, we demonstrate that integrated imaging is maturing into a powerful tool for accurate molecular localisation to structure. PMID:24637200

  15. High-Efficiency Blue Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence from Phenoxaphosphine and Phenoxathiin Derivatives.

    PubMed

    Lee, Sae Youn; Adachi, Chihaya; Yasuda, Takuma

    2016-06-01

    High-efficiency blue thermally activated delayed fluorescence (TADF) molecules, consisting of phenoxaphosphine oxide and phenoxathiin dioxide as acceptor units and 9,9-dimethylacridan as a donor unit, are reported. Maximum external electroluminescence quantum efficiencies of up to 20.5% are achieved in blue organic light-emitting diodes (OLEDs) by employing these materials as TADF emitters. PMID:27059783

  16. Using peel fluorescence in black light rooms to identify navel oranges with shorter storage life and poor rind quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this project is to minimize postharvest decay losses of fresh citrus fruits. Among the approaches recently examined was peel fluorescence under ultraviolet light. In addition to its usual application to identify fruit with developing decay lesions (“blister” or “clear” rot) in black...

  17. Zinc complexes exhibiting highly efficient thermally activated delayed fluorescence and their application to organic light-emitting diodes.

    PubMed

    Sakai, Yumi; Sagara, Yuta; Nomura, Hiroko; Nakamura, Nozomi; Suzuki, Yoshitake; Miyazaki, Hiroshi; Adachi, Chihaya

    2015-02-21

    Metal complexes emitting thermally activated delayed fluorescence based on intra-ligand charge transfer and enhanced by metallization were synthesized. Organic light-emitting diodes using a thermally stable zinc complex processed by vacuum vapor deposition achieved an external quantum efficiency of nearly 20%. PMID:25605520

  18. Elemental mercury emission in the indoor environment due to broken compact fluorescent light (CFL) bulbs--paper

    EPA Science Inventory

    Compact fluorescent light (CFL) bulbs contain a few milligrams (mg) of elemental mercury. When a CFL breaks, some of the mercury is immediately released as elemental mercury vapor and the remainder is deposited on indoor surfaces with the bulb debris. In a controlled study design...

  19. Dynamic Response of Plant Chlorophyll Fluorescence to Light, Water and Nutrient Availability

    NASA Astrophysics Data System (ADS)

    Cendrero Mateo, M. D. P.; Moran, S. M.; Porcar-Castell, A.; Carmo-Silva, A. E.; Papuga, S. A.; Matveeva, M.; Wieneke, S.; Rascher, U.

    2014-12-01

    Photosynthesis is the most important exchange process of CO2 between the atmosphere and the land-surface. Spatial and temporal patterns of photosynthesis depend on dynamic plant-specific adaptation strategies to highly variable environmental conditions e.g. light, water, and nutrient availability. Chlorophyll fluorescence (ChF) has been proposed as a direct indicator of photosynthesis, and several studies have demonstrated its relationship with vegetation functioning at leaf and canopy level. In this study, two overarching questions about ChF were addressed: Q1) How water, nutrient and ambient light conditions determine the relationships between photosynthesis and ChF? Which is the optimum irradiance level for detecting water and nutrient deficit conditions with ChF?; Q2) What is the seasonal relationship between photosynthesis and ChF when nitrogen is the limiting factor? The results of this study indicated that when the differences between treatments (water or nitrogen) drive the relationship between photosynthesis and ChF, ChF has a direct relationship with photosynthesis. This study demonstrates that the light level at which plants were grown was optimum for detecting water and nutrient deficit with ChF. Further, the seasonal relation between photosynthesis and ChF with nitrogen stress was not a simple linear function due to the complex physiological relation between photosynthesis and ChF. Our study showed that at times in the season when nitrogen was sufficient and photosynthesis was highest, ChF decreased because these two processes compete for available energy. The results from this study demonstrated that ChF is a reliable indicator of plant stress and has great potential as a tool for better understand where, when, and how CO2 is exchanged between the land and atmosphere.

  20. Comparative Mutagenesis Studies of Retinal Release in Light-Activated Zebrafish Rhodopsin Using Fluorescence Spectroscopy.

    PubMed

    Morrow, J M; Chang, B S W

    2015-07-28

    Rhodopsin is the visual pigment responsible for initiating scotopic (dim-light) vision in vetebrates. Once activated by light, release of all-trans-retinal from rhodopsin involves hydrolysis of the Schiff base linkage, followed by dissociation of retinal from the protein moiety. This kinetic process has been well studied in model systems such as bovine rhodopsin, but not in rhodopsins from cold-blooded animals, where physiological temperatures can vary considerably. Here, we characterize the rate of retinal release from light-activated rhodopsin in an ectotherm, zebrafish (Danio rerio), demonstrating in a fluorescence assay that this process occurs more than twice as fast as bovine rhodopsin at similar temperatures in 0.1% dodecyl maltoside. Using site-directed mutagenesis, we found that differences in retinal release rates can be attributed to a series of variable residues lining the retinal channel in three key structural motifs: an opening in metarhodopsin II between transmembrane helix 5 (TM5) and TM6, in TM3 near E122, and in the "retinal plug" formed by extracellular loop 2 (EL2). The majority of these sites are more proximal to the β-ionone ring of retinal than the Schiff base, indicating their influence on retinal release is more likely due to steric effects during retinal dissociation, rather than alterations to Schiff base stability. An Arrhenius plot of zebrafish rhodopsin was consistent with this model, inferring that the activation energy for Schiff base hydrolysis is similar to that of bovine rhodopsin. Functional variation at key sites identified in this study is consistent with the idea that retinal release might be an adaptive property of rhodopsin in vertebrates. Our study is one of the few investigating a nonmammalian rhodopsin, which will help establish a better understanding of the molecular mechanisms contributing to vision in cold-blooded vertebrates. PMID:26098991

  1. Light sheet-based fluorescence microscopy (LSFM) reduces phototoxic effects and provides new means for the modern life sciences

    NASA Astrophysics Data System (ADS)

    Pampaloni, Francesco; Ansari, Nari; Girard, Philippe; Stelzer, Ernst H. K.

    2011-07-01

    Most optical technologies are applied to flat, basically two-dimensional cellular systems. However, physiological meaningful information relies on the morphology, the mechanical properties and the biochemistry of a cell's context. A cell requires the complex three-dimensional relationship to other cells. However, the observation of multi-cellular biological specimens remains a challenge. Specimens scatter and absorb light, thus, the delivery of the probing light and the collection of the signal light become inefficient; many endogenous biochemical compounds also absorb light and suffer degradation of some sort (photo-toxicity), which induces malfunction of a specimen. In conventional and confocal fluorescence microscopy, whenever a single plane, the entire specimen is illuminated. Recording stacks of images along the optical Z-axis thus illuminates the entire specimen once for each plane. Hence, cells are illuminated 10-20 and fish 100-300 times more often than they are observed. This can be avoided by changing the optical arrangement. The basic idea is to use light sheets, which are fed into the specimen from the side and overlap with the focal plane of a wide-field fluorescence microscope. In contrast to an epi-fluorescence arrangement, such an azimuthal fluorescence arrangement uses two independently operated lenses for illumination and detection. Optical sectioning and no photo-toxic damage or photo-bleaching outside a small volume close to the focal plane are intrinsic properties. Light sheet-based fluorescence microscopy (LSFM) takes advantage of modern camera technologies. LSFM can be operated with laser cutters and for fluorescence correlation spectroscopy. During the last few years, LSFM was used to record zebrafish development from the early 32-cell stage until late neurulation with sub-cellular resolution and short sampling periods (60-90 sec/stack). The recording speed was five 4-Megapixel large frames/sec with a dynamic range of 12-14 bit. We followed

  2. Environmental air degradation in Dar es Salaam by x-ray fluorescence.

    PubMed

    Koleleni, Y I A

    2002-03-01

    In Dar es Salaam a study of the aerosol contents was conducted and particulate matter on the filters were collected using an Andersen PM10 impactor to determine the environmental air pollution. The contents were determined by X-ray fluorescence analysis. In this study sources of environmental degradation and the concentrations were named as follows: Combustion processes with range of Br from 10 to 800 ng/m3, Pb from 30 to 790 ng/m3. Industrial processes with range of Fe from 37 to 883 ng/m3, Cu from 14 to 310 ng/m3, Zn from 6 to 820ng/m3. Top soil activities with range of K from 20 to 540 ng/m3, Ca from 24 to 3805 ng/m3, Ti from 2 to 59 ng/m3, Mn from 10 to 386 ng/m3. Marine processes with range of Cl from 20 to 310 ng/m3, S from 72 to 134 ng/m3. PMID:11930944

  3. Development and Testing of an Air Fluorescence Imaging System for the Detection of Radiological Contamination

    SciTech Connect

    Inrig, Elizabeth; Koslowsky, Vern; Andrews, Bob; Dick, Michael; Forget, Patrick; Ing, Harry; Hugron, Roger; Wong, Larry

    2011-12-13

    Detection of radionuclides emitting short-range radiation, such as {alpha} and low-energy {beta} particles, has always presented a challenge, particularly when such radionuclides are dispersed over a wide area. In this situation, conventional detection methods require the area of interest to be surveyed using a fragile probe at very close range--a slow, error-prone, and potentially dangerous process that may take many hours for a single room. The instrument under development uses a novel approach by imaging radiation-induced fluorescence in the air surrounding a contaminated area, rather than detecting the radiation directly. A robust and portable system has been designed and built that will allow contaminated areas to be rapidly detected and delineated. The detector incorporates position-sensitive photo-multiplier tubes, UV filters, a fast electronic shutter and an aspherical phase mask that significantly increases the depth-of-field. Preliminary tests have been conducted using sealed {sup 241}Am sources of varying activities and surface areas. The details of the instrument design will be described and the results of recent testing will be presented.

  4. Air leak seal for lung dissection plane with diode laser irradiation: monitoring heat-denature with auto-fluorescence

    NASA Astrophysics Data System (ADS)

    Gotoh, Maya; Arai, Tsunenori

    2008-02-01

    We studied the monitoring of heat-denature by autofluorescence spectrum from lung dissection plane during laser air leak sealing procedure. In order to seal the air leakage from lung in thoracotomy, we proposed novel laser sealing method with the combination of the diode laser (810nm wavelength) irradiation and indocyanine green staining (peak absorption wavelength: 805 nm). This sealing method is expected to preserve the postoperative ventilatory capacity and achieve minimally invasive surgery. We previously reported that this laser sealing only requires thin sealing margin (less than 300 μm in thickness) compared with that of the suturing or stapling. The most serious issue on the laser air leak sealing might be re-air-leakage due to rigid surface layer caused by excessive heat-denature, such as carbonization. We should achieve laser air leak sealing minimizing the degree of heat denature. Dissection planes of isolated porcine lung with /without the diode laser irradiation were prepared as samples. We measured the auto-fluorescence from these samples using a spectrometer. When the diode laser was irradiated with 400J/cm2, the surface of diode laser irradiated lung was fully carbonized. The ration of auto-fluorescence emission of 450nm / 500 nm, with 280 nm excitation wavelength was decreased less tha 50 % of initial value. That of 600 nm / 500 nm was increased over 700 % of initial value. The decreasing of the 450 nm auto-fluorescence intensity might be attributed to the heat-denaturing of the interstitial collagen in lung. However, increasing of the 600 nm didn't specify the origins, we suppose it might be originated from heat-denature substance, like carbonization. We could establish the useful monitoring for lung heat-denaturing with simple methodology. We think the auto-fluorescence measurement can be helpful not only for understanding the sealing mechanism, but also for controlling the degree of heat-denaturing during the procedure.

  5. Investigating the light absorption in a single pass through the photoreceptor layer by means of the lipofuscin fluorescence.

    PubMed

    Prieto, Pedro M; McLellan, James S; Burns, Stephen A

    2005-07-01

    Reflection densitometry has been widely used to measure the density difference of the bleachable cone photopigments in human eyes. Most such measurements make a series of assumptions concerning the amount of scattered light to derive an estimate of the true cone photopigment density from the density difference measurements. The current study made three types of measurements of the light returning from the eye before and after bleaching: the amount of light returning in the "directed" reflection, which is a double-pass estimate of the cone photopigment density; the amount of light in undirected or diffuse reflection; and the amount of fluorescence from lipofuscin in the RPE, which provides a single-pass measurement of optical density difference. For a 1 deg foveally fixated field, the density difference estimates for the three measurements were 0.68, 0.21, and 0.22 respectively. The lipofuscin fluorescence was found to be unguided. The background density difference was non-negligible and very close to the single pass estimate from fluorescence. These measurements each involve potentially different pathways of light through the retina, and therefore place different constraints on models of these pathways. A simple model comparing the directional and the fluorescence optical densities produced retinal coverage estimates around 70-75%. Estimates of the shape factor of the single pass optical Stiles-Crawford effect were evaluated from the dark-adapted and bleached fluorescence measurements. The values were closer to those obtained from psychophysical methods than to the double pass optical Stiles-Crawford shape factors obtained directly from retinal reflectometry. PMID:15820514

  6. Numerical evaluation of droplet sizing based on the ratio of fluorescent and scattered light intensities (LIF/Mie technique)

    SciTech Connect

    Charalampous, Georgios; Hardalupas, Yannis

    2011-03-20

    The dependence of fluorescent and scattered light intensities from spherical droplets on droplet diameter was evaluated using Mie theory. The emphasis is on the evaluation of droplet sizing, based on the ratio of laser-induced fluorescence and scattered light intensities (LIF/Mie technique). A parametric study is presented, which includes the effects of scattering angle, the real part of the refractive index and the dye concentration in the liquid (determining the imaginary part of the refractive index). The assumption that the fluorescent and scattered light intensities are proportional to the volume and surface area of the droplets for accurate sizing measurements is not generally valid. More accurate sizing measurements can be performed with minimal dye concentration in the liquid and by collecting light at a scattering angle of 60 deg. rather than the commonly used angle of 90 deg. Unfavorable to the sizing accuracy are oscillations of the scattered light intensity with droplet diameter that are profound at the sidescatter direction (90 deg.) and for droplets with refractive indices around 1.4.

  7. Daylighting with Mirror Light Pipes and with Fluorescent Planar Concentrators. First Results from the Demonstration Project Stuttgart-Hohenheim

    NASA Astrophysics Data System (ADS)

    Zastrow, Armin; Wittwer, Volker

    1987-02-01

    Efficient daylighting systems have recently attracted increasing interest due to their potential for saving a condiderable amount of electrical energy used for lighting purposes. In this paper we discuss the properties of daylighting systems based on either fluorescent planar concentrators (FPC's) and transparent light guiding plates or light pipes coated with a highly reflective silver coated plastic film (3M Silverlux film). First results on daylighting systems in the students' living quarters in Stuttgart-Hohenheim will be presented. This is a demonstration project which is supported by the Commission of the European Communities.

  8. A simple and sensitive fluorescence method for the determination of trace ozone in air using acridine red as a probe.

    PubMed

    Liu, Qingye; Lin, Chenyin; Zhang, Xinghui; Wen, Guiqing; Liang, Aihui

    2014-12-01

    The ozone in an air sample was trapped by H3 BO3 -LK solution to produce iodine (I2) that interacted with excess I(-) to form I3(-). In pH 4.0 acetate buffer solutions, the I3(-) reacted with acridine red to form acridine red-I3 ion association particles that resulted in the fluorescence peak decreased at 553 nm. The decreased value ΔF553 nm is linear to the O3 concentration in the range 0.08-53.3 × 10(-6) mol/L, with a detection limit of 4 × 10(-8) mol/L. This fluorescence method was used to determine ozone in air samples, and the results were in agreement with that of indigo carmine spectrophotometry. PMID:24733669

  9. High-light stress and photoprotection in Umbilicaria antarctica monitored by chlorophyll fluorescence imaging and changes in zeaxanthin and glutathione.

    PubMed

    Barták, M; Hájek, J; Vráblíková, H; Dubová, J

    2004-05-01

    The effect of high light on spatial distribution of chlorophyll (Chl) fluorescence parameters over a lichen thallus (Umbilicaria antarctica) was investigated by imaging of Chl fluorescence parameters before and after exposure to high light (1500 micro mol m (-2) s (-1), 30 min at 5 degrees C). False colour images of F (V)/F (M) and Phi (II) distribution, taken over thallus with 0.1 mm (2) resolution, showed that maximum F (V)/F (M) and Phi (II) values were located close to the thallus centre. Minimum values were typical for thallus margins. After exposure to high light, a differential response of F (V)/F (M) and Phi (II) was found. The marginal thallus part exhibited a loss of photosynthetic activity, manifested as a lack of Chl fluorescence signal, and close-to-centre parts showed a different extent of F (V)/F (M) and Phi (II) decrease. Subsequent recovery in the dark led to a gradual return of F (V)/F (M) and Phi (II) to their initial values. Fast (30 min) and slow (1 - 22 h) phase of recovery were distinguished, suggesting a sufficient capacity of photoprotective mechanisms in U. antarctica to cope with low-temperature photoinhibition. Glutathione and xanthophyll cycle pigments were analyzed by HPLC. High light led to an increase in oxidized glutathione (GSSG), and a conversion of violaxanthin to zeaxanthin, expressed as their de-epoxidation state (DEPS). The responses of GSSG and DEPS were reversible during subsequent recovery in the dark. GSSG and DEPS were highly correlated to non-photochemical quenching (NPQ), indicating involvement of these antioxidants in the resistance of U. antarctica to high-light stress. Heterogeneity of Chl fluorescence parameters over the thallus and differential response to high light are discussed in relation to thallus anatomy and intrathalline distribution of the symbiotic alga Trebouxia sp. PMID:15143442

  10. Light Transmission Fluctuations from Extended Air Showers Produced by Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, Stuart

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. N o rth Mirror Fields of View

  11. Peptide-Induced AIEgen Self-Assembly: A New Strategy to Realize Highly Sensitive Fluorescent Light-Up Probes.

    PubMed

    Han, Aitian; Wang, Huaimin; Kwok, Ryan T K; Ji, Shenglu; Li, Jun; Kong, Deling; Tang, Ben Zhong; Liu, Bin; Yang, Zhimou; Ding, Dan

    2016-04-01

    Fluorescent light-up probes with aggregation-induced emission (AIE) characteristics have recently attracted great research interest due to their intelligent fluorescence activation mechanism and excellent photobleaching resistance. In this work, we report a new, simple, and generic strategy to design and prepare highly sensitive AIE fluorescent light-up bioprobe through facile incorporation of a self-assembling peptide sequence GFFY between the recognition element and the AIE luminogen (AIEgen). After the bioprobes respond to the targets, the peptide GFFY is capable of inducing the ordered self-assembly of AIEgens, yielding close and tight intermolecular steric interactions to restrict the intramolecular motions of AIEgens for excellent signal output. Using two proof-of-concepts, we have demonstrated that self-assembling peptide-incorporating AIE light-up probes show much higher sensitivity in sensing the corresponding targets in both solutions and cancer cells as compared to those without GFFY induced self-assembly. Taking the probe TPE-GFFYK(DVEDEE-Ac), for example, a detection limit as low as 0.54 pM can be achieved for TPE-GFFYK(DVEDEE-Ac) in caspase-3 detection, which is much lower than that of TPE-K(DVED-Ac) (3.50 pM). This study may inspire new insights into the design of advanced fluorescent molecular probes. PMID:26948051

  12. Nonperturbative theory for the optical response to strong light of the light harvesting complex II of plants: Saturation of the fluorescence quantum yield

    NASA Astrophysics Data System (ADS)

    Richter, M.; Renger, Th.; Renger, G.; Knorr, A.

    2007-08-01

    Recent progress in resolution of the structure of the light harvesting complex II provides the basis for theoretical predictions on nonlinear optical properties from microscopic calculations. An approach to absorption and fluorescence is presented within the framework of Bloch equations using a correlation expansion of relevant many particle interactions. The equations derived within the framework of this theory are applied to describe fluorescence saturation phenomena. The experimentally observed decrease of the normalized fluorescence quantum yield from 1 to 0.0001 upon increasing the intensity of laser pulse excitation at 645nm by five orders of magnitude [R Schödel et al., Biophys. J. 71, 3370 (1996)] is explained by Pauli blocking effects of optical excitation and excitation energy transfer.

  13. Interaction of Light Filaments Generated by Femtosecond Laser Pulses in Air

    SciTech Connect

    Xi Tingting; Lu Xin; Zhang Jie

    2006-01-20

    The interaction of two light filaments propagating in air is simulated. Simulations show that the interaction of the two light filaments displays interesting features such as attraction, fusion, repulsion, and spiral propagation, depending on the relative phase shift and the crossing angle between them. A long and stable channel can be formed by fusing two in-phase light filaments. The channel becomes unstable with the increase of the crossing angle and phase shift. The interaction of two light filaments in different planes is studied and the spiral propagation is observed.

  14. Quantification of Canine Dental Plaque Using Quantitative Light-Induced Fluorescence.

    PubMed

    Wallis, Corrin; Gill, Yadvinder; Colyer, Alison; Davis, Ian; Allsopp, Judi; Komarov, Gleb; Higham, Susan; Harris, Stephen

    2016-03-01

    The aim of this work was to evaluate Quantitative Light-induced Fluorescence (QLF) as an alternative to the established Logan and Boyce method for determining plaque coverage of dogs' teeth. In a series of studies in conscious and anesthetized dogs, QLF showed good intra-photographer repeatability (coefficient of variation [CV] of 7.5% for undisclosed teeth) and inter-photographer reproducibility (CV of 3.2% for undisclosed teeth and 8.5% for disclosed teeth). The QLF software accurately identifies areas of plaque as demonstrated by comparison to the variability of 5 human scorers, manually marking plaque on QLF-acquired images (P = 0.1). There was good agreement with the modified Logan and Boyce method in the percentage reduction in plaque accumulation measured when dogs were fed an oral care chew versus no chew. To see a 15% difference in plaque accumulation, which is considered sufficient by the Veterinary Oral Health Council to differentiate between 2 treatments, a retrospective power analysis (90%) of the data established that only 7 dogs would be required, compared to 19 dogs for the modified Logan and Boyce method. QLF is a reliable method for measuring dental plaque in dogs with the added advantage that it is not subjective and requires fewer animals. PMID:27487653

  15. Photon and fluorescence correlation spectroscopy and light scattering of eye-lens proteins at moderate concentrations.

    PubMed Central

    Andries, C; Guedens, W; Clauwaert, J; Geerts, H

    1983-01-01

    The bovine eye-lens protein, alpha L-crystallin, has been studied with photon correlation spectroscopy to obtain the mutual diffusion coefficient, Dm, with fluorescence correlation spectroscopy to determine the tracer diffusion coefficient, DT, and with light scattering to get the isothermal osmotic compressibility (delta pi/delta c) P,T. The concentration dependence of Dm, DT, and (delta pi/delta c) P,T up to a volume fraction phi of the protein of 2.5 x 10(-2) has been interpreted on the basis of four different interaction potentials: (a) an extended hard-sphere potential; (b) a shielded Coulomb potential; (c) a shielded Coulomb interaction where the effect of counterions is included; (d) a simple mixed potential. The three parameters Dm, DT, and (delta pi/delta c) P,T have also been combined in the generalized Stokes-Einstein equation, Dm = [(delta pi/delta c)P,T . (1--phi) . (DT)]/(kappa B . T). Our results indicate that, in the case that photon correlation spectroscopy gives the mutual diffusion coefficient Dm, the applicability of the Stokes-Einstein equation can be questioned; or that, when one assumes the Stokes-Einstein equation to be valid, there is significant discrepancy between the result of photon correlation spectroscopy and Dm. PMID:6626672

  16. 3D Light-Sheet Fluorescence Microscopy of Cranial Neurons and Vasculature during Zebrafish Embryogenesis

    PubMed Central

    Park, Ok Kyu; Kwak, Jina; Jung, Yoo Jung; Kim, Young Ho; Hong, Hyun-Seok; Hwang, Byung Joon; Kwon, Seung-Hae; Kee, Yun

    2015-01-01

    Precise 3D spatial mapping of cells and their connections within living tissues is required to fully understand developmental processes and neural activities. Zebrafish embryos are relatively small and optically transparent, making them the vertebrate model of choice for live in vivo imaging. However, embryonic brains cannot be imaged in their entirety by confocal or two-photon microscopy due to limitations in optical range and scanning speed. Here, we use light-sheet fluorescence microscopy to overcome these limitations and image the entire head of live transgenic zebrafish embryos. We simultaneously imaged cranial neurons and blood vessels during embryogenesis, generating comprehensive 3D maps that provide insight into the coordinated morphogenesis of the nervous system and vasculature during early development. In addition, blood cells circulating through the entire head, vagal and cardiac vasculature were also visualized at high resolution in a 3D movie. These data provide the foundation for the construction of a complete 4D atlas of zebrafish embryogenesis and neural activity. PMID:26429501

  17. Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Zhang, Qisheng; Li, Bo; Huang, Shuping; Nomura, Hiroko; Tanaka, Hiroyuki; Adachi, Chihaya

    2014-04-01

    Organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) have emerged as cheaper alternatives to high-performance phosphorescent OLEDs with noble-metal-based dopants. However, the efficiencies of blue TADF OLEDs are still low at high luminance, limiting full-colour display. Here, we report a blue OLED containing a 9,10-dihydroacridine/diphenylsulphone derivative that has a comparable performance to today's best phosphorescent OLEDs. The device offers an external quantum efficiency of 19.5% and reduced efficiency roll-off characteristics at high luminance. Through computational simulation, we identified six pretwisted intramolecular charge-transfer (CT) molecules with small singlet-triplet CT state splitting but different energy relationships between 3CT and locally excited triplet (3LE) states. Systematic comparison of their excited-state dynamics revealed that CT molecules with a large twist angle can emit efficient and short-lifetime (a few microseconds) TADF when the emission peak energy is high enough and the 3LE state is higher than the 3CT state.

  18. Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model.

    PubMed

    Brown, Daniel J; Pastras, Christopher J; Curthoys, Ian S; Southwell, Cassandra S; Van Roon, Lieke

    2016-09-01

    There are a variety of techniques available to investigate endolymph dynamics, primarily seeking to understand the cause of endolymphatic hydrops. Here we have taken the novel approach of injecting, via a glass micropipette, fluorescein isothiocyanate-dextran (FITC-dex) and artificial endolymph into scala media of anaesthetized guinea pigs, with subsequent imaging of the inner ear using Light Sheet Fluorescence Microscopy (LSFM) as a means to obtain highly resolved 3D visualization of fluid movements. Our results demonstrate endolymph movement into the utricle, semicircular canals and endolymphatic duct and sac when more than 2.5 μl of fluid had been injected into scala media, with no apparent movement of fluid into the perilymphatic compartments. There was no movement of endolymph into these compartments when less than 2.5 μl was injected. The remarkable uptake of the FITC-dex into the endolymphatic duct, including an absorption into the periductal channels surrounding the endolymphatic duct, highlights the functional role this structure plays in endolymph volume regulation. PMID:27377233

  19. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    NASA Technical Reports Server (NTRS)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  20. Light extinction by aerosols during summer air pollution

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Fraser, R. S.

    1983-01-01

    In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.

  1. Levels of Visual Stress in Proficient Readers: Effects of Spectral Filtering of Fluorescent Lighting on Reading Discomfort.

    PubMed

    Loew, Stephen J; Rodríguez, Celestino; Marsh, Nigel V; Jones, Graham L; Núñez, Jose Carlos; Watson, Kenneth

    2015-01-01

    Visual stress (VS) affects reading in 5-12% of the general population and 31-36% of children with reading disorders. Symptoms include print distortions and visual discomfort when reading, and are exacerbated by fluorescent lighting. Prior research has indicated that VS can also affect proficient readers. We therefore examined levels of visual discomfort in a group of expert readers (n = 24) under both standard and spectrally-filtered fluorescent lighting. Participants rated their awareness of six symptoms of VS under each lighting condition. Under the standard condition, 4(16.7%) of the group recorded moderate to high levels of VS. Differences in symptom levels and reading speed between conditions were analysed using the Wilcoxon Signed Rank Test. Under the filter condition, the group reported less discomfort regarding all six symptoms of VS surveyed. The differences were significant with respect to three of the symptoms (p = .029 - p < .001), with a medium effect size in all of them (r = .31 - r = .46) and total score (p = .007; r = .39). Variations in reading proficiency included significantly fewer self-corrections (p = .019) and total errors (p = .004). Here we present evidence that VS-type symptoms of reading discomfort are not confined to populations with reading difficulties and may also occur in proficient readers, and that simple adaptations to fluorescent lighting may alleviate such symptoms. PMID:26255657

  2. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

    PubMed Central

    Uusitalo, E.; Varrela, J.; Lassila, L.; Vallittu, P. K.

    2016-01-01

    Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n = 5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p < 0.05). The increase of the specimen thickness decreased light transmission in all groups (p < 0.005), and moist specimens attenuated light less than air-dried specimens in all thicknesses (p < 0.05). EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness) (p < 0.05). Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm) and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm). Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert's law. PMID:27446954

  3. Time-Resolved Light Scattering and Fluorescence Spectroscopy in Biomedical and Model Random Media

    NASA Astrophysics Data System (ADS)

    Das, Bidyut Baran

    Optical spectroscopy, light scattering and ultrafast time-gated imaging have been shown to offer novel approaches to study the optical characteristics of various biomedical and other random media. Fluorescence spectra from human malignant and nonmalignant breast tissues were measured at 300 nm excitation and a significant spectral difference was found between the two tissue types by using the ratio of fluorescence intensities at 340 and 440 nm. Optical density measurements on thin breast tissues show that the scattering cross-sections of breast tissues are relatively constant over the visible and the uv region. Transport mean free paths and the absorption lengths for various tissues and model random media were measured using time-resolved transmission. The scattering coefficients for human breast and chicken tissues were found to remain relatively constant in 570-630 nm wavelength region while they change significantly at 1064 nm. Chicken breast and fat tissues were found to be good models for human breast tissues as the values of the optical parameters of the two tissue types are about the same. The less scattering observed at 1064 nm makes tissues more transparent in the NIR region making it easier to image in thick tissues. Time-resolved backscattering measurements show that the scattering and the absorption parameters of a random medium can be obtained accurately in a two-fiber configuration as long as the radial distance is more than about seven times the transport mean free path of the sample. The single point source-detection configuration provides a tool to diagnose breast malignancy though it fails to give accurate values of the optical parameters of tissues. This failure is attributed to the invalidity of the diffusion approximation in this experimental configuration. A 2.5 mm thin chicken fat strip was imaged inside a 40 mm thick chicken breast tissue using snake photons at 625 nm with ultrafast time-gated detection. A simple model to describe the effect

  4. Steady state emission of the fluorescent intermediate of Anabaena Sensory Rhodopsin as a function of light adaptation conditions

    NASA Astrophysics Data System (ADS)

    Cheminal, A.; Léonard, J.; Kim, S. Y.; Jung, K.-H.; Kandori, H.; Haacke, S.

    2013-11-01

    Steady-state fluorescence measurements of the first excited state of the anabaena sensory rhodopsin (ASR), and Bacteriorhodopsin are reported for different light stabilization conditions, including the dark-adapted state. We determine the fluorescence spectra of both all-trans (AT), and 13-cis (13C) protonated Schiff base of retinal, and compare the effect of the proteins. Referenced against the fluorescence quantum yield of AT-bR (2.5 × 10-4) we find for AT-ASR, 13C-ASR, and 13C-bR the values of 3.3 × 10-4, 0.8 × 10-4, and 1.7 × 10-4, respectively. Using reported excited state lifetimes, the radiative rates are deduced, and their differences discussed on the basis of a configuration-dependent oscillator strength.

  5. Validation of a Device for Fluorescence Sensing of Rare Circulating Cells with Diffusive Light in an Optical Flow Phantom Model

    PubMed Central

    Zettergren, Eric; Vickers, Dwayne; Runnels, Judith; Lin, Charles P.; Niedre, Mark J.

    2013-01-01

    Detection and quantification of rare circulating cells in biological tissues is an important problem and has many applications in biomedical research. Current methods normally involve extraction of blood samples and counting of cells ex vivo, or the use of microscopy-based fluorescence in vivo flow cytometry. The goal of this work is to develop an instrument for non-invasively enumerating very rare circulating cells in small animals with diffuse light with several orders of magnitude sensitivity improvement versus current approaches. In this work, we describe the design of our system and show that single, fluorescent microspheres can be detected in limb-mimicking optical flow phantoms with varying optical properties chosen to simulate in vivo conditions. Further, we demonstrate single cell counting capabilities using fluorescently (Vybrant-DiD) labeled Jurkat and Multiple Myeloma cells. Ongoing work includes in vivo testing and characterization of our system in mice. PMID:22254354

  6. Effect of Triplet Harvesting on the Lifetime Based on Fluorescence and Phosphorescence in Hybrid White Organic Light Emitting Diodes.

    PubMed

    Lee, Eun; Lee, Ho Won; Yang, Hyung Jin; Sun, Yong; Lee, Jae Woo; Hwang, Kyo Min; Kim, Woo Young; Kim, Young Kwan

    2016-03-01

    We investigated efficient hybrid white organic light emitting diodes (WOLEDs) apply to triplet harvesting (TH) concept based on three complementary colors by mixing containing blue fluorescent emitter with phosphorescent emitters. The TH is to transfer these triplet excitons from a fluorescence to a phosphorescence, where they can decay radiatively. We fabricated several hybrid WOLEDs, having various emitting layer structures with blue fluorescent emitter and red, green phosphorescent emitter. The WOLED exhibited maximum luminous efficiency of 9.02 cd/A, and a maximum external quantum efficiency of 4.17%. The WOLED showed a highly color-stable white emission with the Commission International de L'Éclairage chromaticity of (0.38, 0.36) at 1,000 cd/m2. PMID:27455693

  7. Cobalt phosphide nanowires: efficient nanostructures for fluorescence sensing of biomolecules and photocatalytic evolution of dihydrogen from water under visible light.

    PubMed

    Tian, Jingqi; Cheng, Ningyan; Liu, Qian; Xing, Wei; Sun, Xuping

    2015-04-27

    The detection of specific DNA sequences plays an important role in the identification of disease-causing pathogens and genetic diseases, and photochemical water splitting offers a promising avenue to sustainable, environmentally friendly hydrogen production. Cobalt-phosphorus nanowires (CoP NWs) show a high fluorescence quenching ability and different affinity toward single- versus double-stranded DNA. Based on this result, the utilization of CoP NWs as fluorescent DNA nanosensors with a detection limit of 100 pM and a selectivity down to single-base mismatch was demonstrated. The use of a thrombin-specific DNA aptamer also enabled the selective detection of thrombin. The photoinduced electron transfer from the excited dye that labels the oligonucleotide probe to the CoP semiconductor led to efficient fluorescence quenching, and largely enhanced the photocatalytic evolution of hydrogen from water under visible light. PMID:25721096

  8. Valinomycin sensitivity proves that light-induced thylakoid voltages result in millisecond phase of chlorophyll fluorescence transients.

    PubMed

    Pospísil, Pavel; Dau, Holger

    2002-04-22

    Upon sudden exposure of plants to an actinic light of saturating intensity, the yield of chlorophyll fluorescence increases typically by 200-400% of the initial O-level. At least three distinct phases of these O-J-I-P transients can be resolved: O-J (0.05-5 ms), J-I (5-50 ms), and I-P (50-1000 ms). In thylakoid membranes, the J-I increase accounts for approximately 30% of the total fluorescence increase; in Photosystem II membranes, the J-I phase is always lacking. In the presence of the ionophore valinomycin, which is known to inhibit specifically the formation of membrane voltages, the magnitude of the J-I phase is clearly diminished; in the presence of valinomycin supplemented by potassium, the J-I phase is fully suppressed. We conclude that the light-driven formation of the thylakoid-membrane voltage results in an increase of the chlorophyll excited-state lifetime, a phenomenon explainable by the electric-field-induced shift of the free-energy level of the primary radical pair [Dau and Sauer, Biochim. Biophys. Acta 1102 (1992) 91]. The assignment of the J-I increase in the fluorescence yield enhances the potential of using O-J-I-P fluorescence transients for investigations on photosynthesis in intact organisms. A putative role of thylakoid voltages in protection of PSII against photoinhibitory damage is discussed. PMID:12034474

  9. Color-stable and efficient stacked white organic light-emitting devices comprising blue fluorescent and orange phosphorescent emissive units

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Xue, Qin; Xie, Wenfa; Duan, Yu; Xie, Guohua; Zhao, Yi; Hou, Jingying; Liu, Shiyong; Zhang, Liying; Li, Bin

    2008-10-01

    We have demonstrated two kinds of stacked white organic light-emitting diodes (WOLEDs) employing tri(8-hydroxyquinoline) aluminum:20 wt %Mg/MoO3 as charge generation layer. White light emission can be obtained by mixing blue fluorescence and orange phosphorescence. Stacked WOLED with individual blue fluorescent and orange phosphorescent emissive units has better color stability and higher efficiency than that with double white emissive units, which is attributed to the avoidance of the movement of charges recombination zone and elimination of the Dexter energy transfer between blue and orange emission layers occurring in the latter. The efficiency of the stacked WOLED is 35.9 cd/A at 1000 cd/m2.

  10. High-efficiency yellow double-doped organic light-emitting devices based on phosphor-sensitized fluorescence

    SciTech Connect

    D'Andrade, Brian W.; Baldo, Marc A.; Adachi, Chihaya; Brooks, Jason; Thompson, Mark E.; Forrest, Stephen R.

    2001-08-13

    We demonstrate high-efficiency yellow organic light-emitting devices (OLEDs) employing [2-methyl-6-[2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl-ethenyl]-4H-pyran-4-ylidene] propane-dinitrile (Dcm{sup 2}) as a fluorescent lumophore, with a green electrophospho- rescent sensitizer, fac tris(2-phenylpyridine) iridium [Ir(ppy){sub 3}] co-doped into a 4,4{prime}-N,N{prime}dicarbazole-biphenyl host. The devices exhibit peak external fluorescent quantum and power efficiencies of 9%{+-}1% (25 cd/A) and 17{+-}2 lm/W at 0.01 mA/cm{sup 2}, respectively. At 10 mA/cm{sup 2}, the efficiencies are 4.1%{+-}0.5% (11 cd/A) and 3.1{+-}0.3 lm/W. We show that this exceptionally high performance for a fluorescent dye is due to the {approx}100% efficient transfer of both singlet and triplet excited states in the doubly doped host to the fluorescent material using Ir(ppy){sub 3} as a sensitizing agent. These results suggest that 100% internal quantum efficiency fluorescent OLEDs employing this sensitization process are within reach. {copyright} 2001 American Institute of Physics.

  11. Halide ion controlled shape dependent gold nanoparticle synthesis with tryptophan as reducing agent: Enhanced fluorescent properties and white light emission

    NASA Astrophysics Data System (ADS)

    Kasture, Manasi; Sastry, Murali; Prasad, B. L. V.

    2010-01-01

    We report the synthesis of Au nanoparticles in presence of two surfactants cetyltrimethyl ammonium chloride (CTAC) and cetyltrimethyl ammonium bromide (CTAB) by reducing Au 3+ ions with tryptophan. Interestingly, triangular shaped particles were seen to form in presence of CTAB, while spherical nanoparticles resulted with CTAC. The highlight of this result is the white light emission from the Au triangles obtained when CTAB is used. These results are supported by lifetime measurements and fluorescence.

  12. Elimination of light scatter interference in dual-laser flow cytometry by synchronous detection of emitted fluorescence: theory and demonstration using simulated signals

    NASA Astrophysics Data System (ADS)

    Steinkamp, John A.; Keij, Jan F.

    1999-06-01

    Light scatter is often a source of interference in dual-laser excitation experiments by flow cytometry. If the two laser beams are not adequately separated or optical masking is not used, and if gated sequential fluorescence signal detection is not employed, light scatter from particles/cells as they pass across one beam can interfere in the fluorescence measurement channel of the other laser excitation beam. In this study we discuss the problem and present the theory for improving fluorescence measurements in dual-laser flow cytometry by use of modulated laser excitation and synchronous (phase- sensitive) detection of the resulting fluorescence emission to eliminate light scatter interference from particles/cells. Fluorescence emission from particles/cells generated by the first laser beam (unmodulated cw) is measured using conventional means (detection channel no. 1). Light scatter interference from particles/cells as they pass across the first laser excitation beam, whose wavelength lies in the fluorescence measurement region of detection channel no. 2, is rejected by the synchronously tuned phase-sensitive channel no. 2 detector, whereas the fluorescence emission corresponding to laser no. 2 excitation is detected and measured. The efficacy of the technology in relation to analytical cytology measurements is demonstrated using simulated fluorescence and light scatter signals.

  13. Rate Constants of PSII Photoinhibition and its Repair, and PSII Fluorescence Parameters in Field Plants in Relation to their Growth Light Environments.

    PubMed

    Miyata, Kazunori; Ikeda, Hiroshi; Nakaji, Masayoshi; Kanel, Dhana Raj; Terashima, Ichiro

    2015-09-01

    The extent of photoinhibition of PSII is determined by a balance between the rate of photodamage to PSII and that of repair of the damaged PSII. It has already been indicated that the rate constants of photodamage (kpi) and repair (krec) of the leaves differ depending on their growth light environment. However, there are no studies using plants in the field. We examined these rate constants and fluorescence parameters of several field-grown plants to determine inter-relationships between these values and the growth environment. The kpi values were strongly related to the excess energy, EY, of the puddle model and non-regulated energy dissipation, Y(NO), of the lake model, both multiplied by the photosynthetically active photon flux density (PPFD) level during the photoinhibitory treatment. In contrast, the krec values corrected against in situ air temperature were very strongly related to the daily PPFD level. The plants from the fields showed higher NPQ than the chamber-grown plants, probably because these field plants acclimated to stronger lightflecks than the averaged growth PPFD. Comparing chamber-grown plants and the field plants, we showed that kpi is determined by the incident light level and the photosynthetic capacities such as in situ rate of PSII electron transport and non-photochemical quenching (NPQ) [e.g. Y(NO)×PPFD] and that krec is mostly determined by the growth light and temperature levels. PMID:26203120

  14. Mice lung disease follow-up with open-air fluorescence diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Koenig, Anne; Gonon, Georges; Hervé, Lionel; Berger, Michel; Dinten, Jean-Marc; Boutet, Jérôme; Josserand, Véronique; Coll, Jean-Luc; Peltié, Philippe; Rizo, Philippe

    2009-07-01

    A fluorescence diffuse optical tomography instrument including a dedicated reconstruction scheme which accounts for the medium optical heterogeneities is presented. It allows non-contact measurements and does not require animal immersion in an optical adaptation liquid.

  15. Review of organic light-emitting diodes with thermally activated delayed fluorescence emitters for energy-efficient sustainable light sources and displays

    NASA Astrophysics Data System (ADS)

    Volz, Daniel

    2016-04-01

    Thermally activated delayed fluorescence (TADF) is an emerging hot topic. Even though this photophysical mechanism itself has been described more than 50 years ago and optoelectronic devices with organic matter have been studied, improved, and even commercialized for decades now, the realization of the potential of TADF organic light-emitting diodes (OLEDs) happened only recently. TADF has been proven to be an attractive and very efficient alternative for phosphorescent materials, such as dopants in OLEDs, light-emitting electrochemical cells as well as potent emitters for chemiluminescence. In this review, the TADF concept is introduced in terms that are also understandable for nonchemists. The basic concepts behind this mechanism as well as state-of-the-art examples are discussed. In addition, the future economic impact, especially for the lighting and display market, is addressed here. We conclude that TADF materials are especially helpful to realize efficient, durable deep blue and white displays.

  16. Method for measuring temperatures and densities in hypersonic wind tunnel air flows using laser-induced O2 fluorescence

    NASA Technical Reports Server (NTRS)

    Laufer, Gabriel; Mckenzie, Robert L.; Fletcher, Douglas G.

    1990-01-01

    Laser-induced fluorescence in oxygen, in combination with Raman scattering, is shown to be an accurate means by which temperature, density, and their fluctuations owing to turbulence can be measured in air flows associated with high-speed wind tunnels. For temperatures above 60 K and densities above 0.01 amagat, the uncertainties in the temperature and density measurements can be less than 2 percent, if the signal uncertainties are dominated by photon statistical noise. The measurements are unaffected by collisional quenching and can be achieved with laser fluences for which nonlinear effects are insignificant. Temperature measurements using laser-induced fluorescence alone have been demonstrated at known densities in the range of low temperatures and densities which are expected in a hypersonic wind tunnel.

  17. A method for measuring temperatures and densities in hypersonic wind tunnel air flows using laser-induced O2 fluorescence

    NASA Technical Reports Server (NTRS)

    Laufer, Gabriel; Fletcher, Douglas G.; Mckenzie, Robert L.

    1990-01-01

    Laser-induced fluorescence in oxygen, in combination with Raman scattering, is shown to be an accurate means by which temperature, density, and their fluctuations due to turbulence can be measured in air flows associated with high-speed wind tunnels. For temperatures above 60 K and densities above 0.01 amagat, the uncertainty in the temperature and density measurements can be less than 2 and 3 percent, respectively, if the signal uncertainties are dominated by photon-statistical noise. The measurements are unaffected by collisional quenching and can be achieved with laser fluences for which nonlinear effects are insignificant. Temperature measurements using laser-induced fluorescence alone have been demonstrated at known densities in the range of low temperatures and densities which are expected in a hypersonic wind tunnel.

  18. Effects of water stress and light intensity on chlorophyll fluorescence parameters and pigments of Aloe vera L.

    PubMed

    Hazrati, Saeid; Tahmasebi-Sarvestani, Zeinolabedin; Modarres-Sanavy, Seyed Ali Mohammad; Mokhtassi-Bidgoli, Ali; Nicola, Silvana

    2016-09-01

    Aloe vera L. is one of the most important medicinal plants in the world. In order to determine the effects of light intensity and water deficit stress on chlorophyll (Chl) fluorescence and pigments of A. vera, a split-plot in time experiment was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of three light intensities (50, 75 and 100% of sunlight) and four irrigation regimes (irrigation after depleting 20, 40, 60 and 80% of soil water content) were considered as main factors. Sampling time was considered as sub factor. The first, second and third samplings were performed 90, 180 and 270 days after imposing the treatments, respectively. The results demonstrated that the highest light intensity and the severe water stress decreased maximum fluorescence (Fm), variable fluorescence (Fv)/Fm, quantum yield of PSII photochemistry (ФPSII), Chl and photochemical quenching (qP) but increased non-photochemical quenching (NPQ), minimum fluorescence (F0) and Anthocyanin (Anth). Additionally, the highest Fm, Fv/Fm, ФPSII and qP and the lowest NPQ and F0 were observed when 50% of sunlight was blocked and irrigation was done after 40% soil water depletion. Irradiance of full sunlight and water deficit stress let to the photoinhibition of photosynthesis, as indicated by a reduced quantum yield of PSII, ФPSII, and qP, as well as higher NPQ. Thus, chlorophyll florescence measurements provide valuable physiological data. Close to half of total solar radiation and irrigation after depleting 40% of soil water content were selected as the most efficient treatments. PMID:27161580

  19. PsbS is required for systemic acquired acclimation and post-excess-light-stress optimization of chlorophyll fluorescence decay times in Arabidopsis

    PubMed Central

    Ciszak, Kamil; Kulasek, Milena; Barczak, Anna; Grzelak, Justyna; Maćkowski, Sebastian; Karpiński, Stanisław

    2015-01-01

    Systemic acquired acclimation (SAA) is an important light acclimatory mechanism that depends on the global adjustments of non-photochemical quenching and chloroplast retrograde signaling. As the exact regulation of these processes is not known, we measured time-resolved fluorescence of chlorophyll a in Arabidopsis thaliana leaves exposed to excess light, in leaves undergoing SAA, and in leaves after excess light episode. We compare the behavior induced in wild-type plants with null mutant of non-photochemical quenching (npq4–1). The wild type rosettes exhibit a small reduction of fluorescence decay times in leaves directly exposed to excess light and in leaves undergoing SAA in ambient low light. However in npq4–1 exposition to excess light results in much faster fluorescence decay, which is insensitive to excitation power. At the same time npq4–1 leaves undergoing SAA displayed intermediate fluorescence decay. The npq4–1 plants also lost the ability to optimize florescence decay, and thus chlorophyll a dynamics up to 2 h after excess light episode. The fluorescence decay dynamics in both WT and npq4–1 can be described by a set of 3 maximum decay times. Based on the results, we concluded that functional PsbS is required for optimization of absorbed photon fate and optimal light acclimatory responses such as SAA or after excess light stress. PMID:25654166

  20. A ratiometric fluorescent probe for hyaluronidase detection via hyaluronan-induced formation of red-light emitting excimers.

    PubMed

    Hu, Qinghua; Zeng, Fang; Wu, Shuizhu

    2016-05-15

    Hyaluronidase (HAase), which is involved in various physiological and pathological processes, can selectively degrade hyaluronan (HA) into small fragments, and it has been reported as a diagnostic and prognostic biomarker for bladder cancer. Herein, a facile ratiometric fluorescent sensing system for HAase has been developed, which is based on hyaluronan-induced formation of red-light emitting excimers and can realize sensitive detection of HAase with a detection limit of 0.007 U/mL. A positively-charged pyrene analog (N-Py) has been synthesized and then mixed with the negatively-charged HA, due to electrostatic interaction between the two components, aggregation along with the N-Py excimers readily form which emits red light. While in the presence of HAase, the enzyme catalyzes the hydrolysis of HA into small fragments, which in turn triggers disassembly of excimers; consequently the N-Py excimer emission turns into monomer emission. The emission ratio resulted from the excimer-monomer transition can be used as the sensing signal for detecting HAase. The probe features visible-light excitation and red light emission (excimer), which is conducive to reducing possible interference from autofluorescence of biological samples. Furthermore, the assay system can be successfully used to determine HAase in human urine samples with satisfactory accuracy. This strategy may provide a suitable sensitive and accurate assay for HAase as well as an effective approach for developing fluorescent ratiometric assays for other enzymes. PMID:26774093

  1. Effect of light-emitting diode (LED) vs. fluorescent (FL) lighting on laying hens in aviary hen houses: Part 2 - Egg quality, shelf-life and lipid composition.

    PubMed

    Long, H; Zhao, Y; Xin, H; Hansen, H; Ning, Z; Wang, T

    2016-01-01

    In this 60-wk study, egg quality, egg shelf-life, egg cholesterol content, total yolk lipids, and yolk fatty acid composition of eggs produced by Dekalb white laying hens in commercial aviary houses with either light-emitting diode (LED) or fluorescent (FL) lighting were compared. All parameters were measured at 27, 40, and 60 wk of age, except for egg shelf-life, which was compared at 50 wk of age. The results showed that, compared to the FL regimen, the LED regimen resulted in higher egg weight, albumen height, and albumen weight at 27 wk of age, thicker shells at 40 wk of age, but lower egg weight at 60 wk of age. Egg quality change was similar between the lighting regimens during the 62-d egg storage study, indicating that LED lighting did not influence egg shelf-life. Eggs from both lighting regimens had similar cholesterol content. However, cholesterol concentration of the yolk (15.9 to 21.0 mg cholesterol/g wet weight yolk) observed in this study was higher than that of United States Department of Agriculture (USDA) database (10.85 mg/g). No significant differences in total lipids or fatty acid composition of the yolks were detected between the two lighting regimens. PMID:26574027

  2. Light induced fluorescence in differentiation of endometrial pathology: multivariate statistical treatment

    NASA Astrophysics Data System (ADS)

    Vaitkuviene, Aurelija; Auksorius, E.; Gavryushin, V.; Vaitkus, Juozas V.

    2001-10-01

    The detailed statistical analysis of the tissue fluorescence spectra was proposed for the investigation of tissue biochemical changes. The method is based on the decomposition of the autofluorescence spectrum into the spectra of natural components of cells. The human tissues with different physiological activity or affected by sickness were investigated. The tissue spectra changes are grouped by the histology data. The observed correlation of fluorescence spectra structure changes for cancer and other 'normal' phases of the tissue are observed from multivariate statistical analysis.

  3. High-efficiency fluorescent white organic light-emitting diodes using double hole-transporting-layers

    NASA Astrophysics Data System (ADS)

    Jou, Jwo-Huei; Shen, Shih-Ming; Chen, Cheng-Chung; Chung, Yu-Chiao; Wang, Chun-Jan; Hsu, Mao-Feng; Wang, Wei-Ben; Wu, Ming-Hsuan; Yang, Chih-Jie; Liu, Chi-Ping

    2008-04-01

    High-efficiency fluorescent white organic light-emitting diodes (OLED) were fabricated by using double holetransporting- layers (HTLs), poly(3,4-ethylene- dioxythiophene)-poly-(styrenesulfonate) (PEDOT) and N,N'-bis-(1- naphthyl)-N,N'-diphenyl-1,10-biphenyl-4-4'-diamine (NPB). The diodes were composed of a single emissive-layer (EML), with 0.5 wt% red 4-(dicyanomethylene)-2-tbutyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped in a mixed-host of 25% trans-1,2-bis(6-(N,N-di-p-tolylamino)-Naphthalene-2-yl)ethene and 75% 1-butyl-9,10-naphthaleneanthracene. The device structure comprised a 125 nm anode layer of indium tin oxide, a 25 nm first HTL of PEDOT, a 0 to 10 nm second HTL of NPB, a 30 nm EML, a 40 nm electron-transporting-layer of 2,2',2"-(1,3,5-benzenetriyl)-tris(1- phenyl-1-H-benzimidazole), a 1 nm electron-injection-layer of lithium fluoride and a 150 nm cathode layer of aluminum. With the addition of a 7.5 nm second HTL (NPB), the resultant power-efficiency at 100 cd/m2, for example, was increased from 11.9 to 18.9 lm/W, an improvement of 59%. The improvement was even more marked at 1,000 cd/m2, i.e. that the power-efficiency was increased from 9.1 to 16.5 lm/W, an improvement of 81%. The marked efficiency improvement may be attributed to a better balance of carrier-injection in the desired emissive zone since the addition of the NPB layer in between the first HTL and the EML may have effectively reduced the injection of excessive holes into the EML due to the relatively high energy-barrier to hole, which was 0.5 eV, at the interface of the two HTLs. The resultant hole-blocking function was plausibly more effective at higher voltage so that comparatively much less holes would be injected into the EML, leading to a much better balanced carrier-injection and consequently a higher efficiency-improvement at the higher brightness.

  4. A Review of the Reflector Compact Fluorescent Lights Technology Procurement Program: Conclusions and Results

    SciTech Connect

    Sandahl, Linda J.; Gilbride, Theresa L.; Ledbetter, Marc R.; McCullough, Jeffrey J.

    2008-05-19

    This report describes a project sponsored by the U.S. Department of Energy (DOE) and implemented by the Pacific Northwest National Laboratory (PNNL), from 2000 to 2007 to improve the performance of reflector type (R-lamp) compact fluorescent lamps (CFLs) and increase their availability throughout the United States by means of a technology development and procurement strategy. In 2000, at the request of the U.S. Department of Energy’s Emerging Technologies Program and its predecessors, the Pacific Northwest National Laboratory undertook a technology procurement seeking R-CFLs that were specifically designed for use in ICAT recessed can fixtures and that met other minimum performance criteria including minimum light output and size restrictions (to ensure they fit in standard residential recessed cans). The technology procurement included two phases. In Phase I, requests for proposals (RFPs) were issued in October 2002 and five manufacturers responded with 12 lamp models. Eight of these models met the minimum requirements and passed the 6-hour short-term test in a simulated ICAT environment. These eight models were subjected to long-term tests of 6,000 or more hours in a simulated ICAT environment. Three of these models passed the short- and long-term tests and were promoted through the program website (www.pnl.gov/rlamps), press releases, and fliers. To increase the number of qualifying models, a second RFP was issued in June 2005. In April 2007, DOE announced that 16 reflector CFL (R-CFL) models by four manufacturers had met all the minimum requirements of Phase 2 of the R-CFL Technology Innovation Competition. PNNL developed both the criteria and the test apparatus design for Elevated Temperature Life Testing (ETLT), which has been included by DOE in its draft ENERGY STAR specifications for the reflector category of CFLs. PNNL promoted the winning lamps through a program website, press releases, and fliers as well as through program partners. PNNL also helped

  5. Organic Fluorescent Dyes Supported on Activated Boron Nitride: A Promising Blue Light Excited Phosphors for High-Performance White Light-Emitting Diodes

    PubMed Central

    Li, Jie; Lin, Jing; Huang, Yang; Xu, Xuewen; Liu, Zhenya; Xue, Yanming; Ding, Xiaoxia; Luo, Han; Jin, Peng; Zhang, Jun; Zou, Jin; Tang, Chengchun

    2015-01-01

    We report an effective and rare-earth free light conversion material synthesized via a facile fabrication route, in which organic fluorescent dyes, i.e. Rhodamine B (RhB) and fluorescein isothiocyanate (FITC) are embedded into activated boron nitride (αBN) to form a composite phosphor. The composite phosphor shows highly efficient Förster resonance energy transfer and greatly improved thermal stability, and can emit at broad visible wavelengths of 500–650 nm under the 466 nm blue-light excitation. By packaging of the composite phosphors and a blue light-emitting diode (LED) chip with transparent epoxy resin, white LED with excellent thermal conductivity, current stability and optical performance can be realized, i.e. a thermal conductivity of 0.36 W/mk, a Commission Internationale de 1'Eclairage color coordinates of (0.32, 0.34), and a luminous efficiency of 21.6 lm·W−1. Our research opens the door toward to the practical long-life organic fluorescent dyes-based white LEDs. PMID:25682730

  6. Organic Fluorescent Dyes Supported on Activated Boron Nitride: A Promising Blue Light Excited Phosphors for High-Performance White Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Li, Jie; Lin, Jing; Huang, Yang; Xu, Xuewen; Liu, Zhenya; Xue, Yanming; Ding, Xiaoxia; Luo, Han; Jin, Peng; Zhang, Jun; Zou, Jin; Tang, Chengchun

    2015-02-01

    We report an effective and rare-earth free light conversion material synthesized via a facile fabrication route, in which organic fluorescent dyes, i.e. Rhodamine B (RhB) and fluorescein isothiocyanate (FITC) are embedded into activated boron nitride (αBN) to form a composite phosphor. The composite phosphor shows highly efficient Förster resonance energy transfer and greatly improved thermal stability, and can emit at broad visible wavelengths of 500-650 nm under the 466 nm blue-light excitation. By packaging of the composite phosphors and a blue light-emitting diode (LED) chip with transparent epoxy resin, white LED with excellent thermal conductivity, current stability and optical performance can be realized, i.e. a thermal conductivity of 0.36 W/mk, a Commission Internationale de 1'Eclairage color coordinates of (0.32, 0.34), and a luminous efficiency of 21.6 lm.W-1. Our research opens the door toward to the practical long-life organic fluorescent dyes-based white LEDs.

  7. Bili lights

    MedlinePlus

    Phototherapy for jaundice; Bilirubin - bili lights; Neonatal care - bili lights; Newborn care - bili lights ... Phototherapy involves shining fluorescent light from the bili lights on bare skin. A specific wavelength of light can break down bilirubin into a form that ...

  8. Fluorescence imaging of microbe-containing particles shot from a two-stage Light-gas gun into an aerogel.

    PubMed

    Kawaguchi, Yuko; Sugino, Tomohiro; Tabata, Makoto; Okudaira, Kyoko; Imai, Eichi; Yano, Hajime; Hasegawa, Sunao; Hashimoto, Hirofumi; Yabuta, Hikaru; Kobayashi, Kensei; Kawai, Hideyuki; Mita, Hajime; Yokobori, Shin-ichi; Yamagishi, Akihiko

    2014-02-01

    We have proposed an experiment (the Tanpopo mission) to capture microbes on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for more than 1 year. After retrieving the aerogel, particle tracks and particles found in it will be visualized by fluorescence microscopy after staining it with a DNA-specific fluorescence dye. In preparation for this study, we simulated particle trapping in an aerogel so that methods could be developed to visualize the particles and their tracks. During the Tanpopo mission, particles that have an orbital velocity of ~8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into the aerogel from a two-stage light-gas gun (acceleration 4.2 km/s). The shapes of the captured particles, and their tracks and entrance holes were recorded with a microscope/camera system for further analysis. The size distribution of the captured particles was smaller than the original distribution, suggesting that the particles had fragmented. We were able to distinguish between microbial DNA and inorganic compounds after staining the aerogel with the DNA-specific fluorescence dye SYBR green I as the fluorescence of the stained DNA and the autofluorescence of the inorganic particles decay at different rates. The developed methods are suitable to determine if microbes exist at the International Space Station altitude. PMID:25086872

  9. Level sequence and splitting identification of closely spaced energy levels by angle-resolved analysis of fluorescence light

    NASA Astrophysics Data System (ADS)

    Wu, Z. W.; Volotka, A. V.; Surzhykov, A.; Dong, C. Z.; Fritzsche, S.

    2016-06-01

    The angular distribution and linear polarization of the fluorescence light following the resonant photoexcitation is investigated within the framework of density matrix and second-order perturbation theory. Emphasis has been placed on "signatures" for determining the level sequence and splitting of intermediate (partially) overlapping resonances, if analyzed as a function of photon energy of incident light. Detailed computations within the multiconfiguration Dirac-Fock method have been performed, especially for the 1 s22 s22 p63 s ,Ji=1 /2 +γ1→(1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 →1 s22 s22 p63 s ,Jf=1 /2 +γ2 photoexcitation and subsequent fluorescence emission of atomic sodium. A remarkably strong dependence of the angular distribution and linear polarization of the γ2 fluorescence emission is found upon the level sequence and splitting of the intermediate (1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 overlapping resonances owing to their finite lifetime (linewidth). We therefore suggest that accurate measurements of the angular distribution and linear polarization might help identify the sequence and small splittings of closely spaced energy levels, even if they cannot be spectroscopically resolved.

  10. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy

    PubMed Central

    2015-01-01

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems. PMID:26061541

  11. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy.

    PubMed

    Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D

    2015-08-19

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems. PMID:26061541

  12. DNA and RNA "traffic lights": synthetic wavelength-shifting fluorescent probes based on nucleic acid base substitutes for molecular imaging.

    PubMed

    Holzhauser, Carolin; Wagenknecht, Hans-Achim

    2013-08-01

    The DNA base substitute approach by the (S)-3-amino-1,2-propanediol linker allows placing two fluorophores in a precise way inside a given DNA framework. The double helical architecture around the fluorophores, especially the DNA-induced twist, is crucial for the desired photophysical interactions. Excitonic, excimer, and energy transfer interactions yield fluorescent DNA and RNA probes with dual emission color readout. Especially, our DNA and RNA "traffic light" that combines the green emission of TO with the red emission of TR represents an important tool for molecular imaging and can be applied as aptasensors and as probes to monitor the siRNA delivery into cells. The concept can be extended to the synthetically easier to access postsynthetic 2'-modifications and the NIR range. Thereby, the pool of tailor-made fluorescent nucleic acid conjugates can be extended. PMID:23796243

  13. Fluorescent optical liquid level sensor

    DOEpatents

    Weiss, Jonathan D.

    2001-01-01

    A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.

  14. Time-resolved spectroscopic study of photofragment fluorescence in methane/air mixtures and its diagnostic implications

    NASA Astrophysics Data System (ADS)

    Jonsson, Malin; Borggren, Jesper; Aldén, Marcus; Bood, Joakim

    2015-09-01

    In this work 80-picosecond laser pulses of 266-nm wavelength with intensities up to (2.0 ± 0.5) × 1011 W/cm2 were used for fragmentation of methane/air gas mixtures at ambient pressure and temperature. Emission spectra are, for the first time, studied with ultrahigh temporal resolution using a streak camera. Fluorescence spectra from CH(A2Δ-X2Π, B2Σ--X2Π, C2Σ+-X2Π), CN(B2Σ+-X2Σ+, Δ v = 0 and Δ v = ±1), NH(A3Π--X3Σ-), OH(A2Σ+-X2Π) and N2 +(B2Σu + X2Σg + were recorded and analyzed. By fitting simulated spectra to high-resolution experimental spectra, rotational and vibrational temperatures are estimated, showing that CH(C), CN(B), NH(A), and OH(A) are formed in highly excited vibrational and rotational states. The fluorescence signal dependencies on laser intensity and CH4/air equivalence ratio were investigated as well as the fluorescence lifetimes. All fragments observed are formed within 200 ps after the arrival of the laser pulse and their fluorescence lifetimes are shorter than 1 ns, except for CN(B-X) Δ v = 0 whose lifetime is 2.0 ns. The CN(B-X) Δ v = 0 fluorescence was studied temporally under high spectral resolution, and it was found that the vibrational levels are not populated simultaneously, but with a rate that decreases with increasing vibrational quantum number. This observation indicates that the rate of the chemical reaction that forms the CN(B) fragments is decreasing with increasing vibrational state of the product. The results provide vital information for the application of laser diagnostic techniques based on strong UV excitation, as they show that such methods might not be entirely non-intrusive and suffering from spectral interferences, unless the laser intensity is kept sufficiently low. Finally, equivalence ratios were determined from "unknown" spectra using multivariate analysis, showing a good agreement with theoretical compositions with an error of 4 %. The method is expected to be a useful diagnostic tool for

  15. Planar Rayleigh scattering and laser-induced fluorescence for visualization of a hot, Mach 2 annular air jet

    NASA Astrophysics Data System (ADS)

    Balla, R. Jeffrey

    1994-10-01

    Planar Rayleigh scattering (PRS) and planar laser-induced fluorescence (PLIF) were used to investigate the vitiated air component of a coaxial hydrogen/vitiated air nonpremixed turbulent jet flame that is ejected at a Mach number of 2. All experiments were performed with a xenon chloride tunable excimer laser. Planar information for both techniques was obtained using laser sheets 6 cm high, 5 cm wide, and 300 micron thick. In this flow field, the effective Rayleigh cross section of the components in the vitiated air was assumed to be independent of composition. Therefore, the PRS technique produced signals which were proportional to total density. When the flow field was assumed to be at a known and uniform pressure, the PRS signal data for the vitiated air could be converted to temperature information. Also, PLIF images were generated by probing the OH molecule. These images contain striation patterns attributed to small localized instantaneous temperature nonuniformities. The results from the PLIF and PRS techniques were used to show that this flow field contains a nongaseous component, most likely liquid water that can be reduced by increasing the settling chamber wall temperature.

  16. Planar Rayleigh scattering and laser-induced fluorescence for visualization of a hot, Mach 2 annular air jet

    NASA Technical Reports Server (NTRS)

    Balla, R. Jeffrey

    1994-01-01

    Planar Rayleigh scattering (PRS) and planar laser-induced fluorescence (PLIF) were used to investigate the vitiated air component of a coaxial hydrogen/vitiated air nonpremixed turbulent jet flame that is ejected at a Mach number of 2. All experiments were performed with a xenon chloride tunable excimer laser. Planar information for both techniques was obtained using laser sheets 6 cm high, 5 cm wide, and 300 micron thick. In this flow field, the effective Rayleigh cross section of the components in the vitiated air was assumed to be independent of composition. Therefore, the PRS technique produced signals which were proportional to total density. When the flow field was assumed to be at a known and uniform pressure, the PRS signal data for the vitiated air could be converted to temperature information. Also, PLIF images were generated by probing the OH molecule. These images contain striation patterns attributed to small localized instantaneous temperature nonuniformities. The results from the PLIF and PRS techniques were used to show that this flow field contains a nongaseous component, most likely liquid water that can be reduced by increasing the settling chamber wall temperature.

  17. Light Transmission From Extended Air Showers Produced By Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, S. F.; Abu-Zayyad, T.; Belov, K.; Cao, Z.; Chen, G.; Jui, C. C. H.; Kieda, D. B.; Matthews, J. N.; Salamon, M.; Sokolsky, P. V.; Smith, J. D.; Sommers, P.; Springer, R. W.; Stokes, B. T.; Thomas, S. B.; Wiencke, L. R.; Matthews, J. A. J.; Clay, R. W.; Dawson, B. R.; Simpson, K.; Bells, J.; Boyer, J.; Knapp, B.; Song, B. H.; Zhang, X. Z.; SDSS Collaboration; High Resolution Fly's Eye Collaboration; Telescope Array/U. Tokyo Collaboration

    1999-05-01

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors, with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. The High Resolution Fly's Eye Collaboration gratefully acknowledges the support of the US National Science Foundation, DOE, the US Army's Dugway Proving Grounds, and the support of our member universities.

  18. CfAIR2: Near-infrared Light Curves of 94 Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Michael F.; Kirshner, Robert P.

    2015-09-01

    CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes {{JHK}}s photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z ˜ 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ˜13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

  19. Multi-channel LED light source for fluorescent agent aided minimally invasive surgery.

    PubMed

    Ren, Jiacheng; Venugopalan, Janani; Xu, Jian; Kairdolf, Brad; Durfee, Robert; Wang, May D

    2014-01-01

    Cancer is one of the most common and deadly diseases around the world. Amongst all the different treatments of cancer such as surgery, chemotherapy and radiation therapy, surgical resection is the most effective. Successful surgeries greatly rely on the detection of the accurate tumor size and location, which can be enhanced by contrast agents. Commercial endoscope light sources, however, offer only white light illumination. In this paper, we present the development of a LED endoscope light source that provides 2 light channels plus white light to help surgeons to detect a clear tumor margin during minimally invasive surgeries. By exciting indocyanine green (ICG) and 5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX), the light source is intended to give the user a visible image of the tumor margin. This light source is also portable, easy to use and costs less than $300 to build. PMID:25571589

  20. Multi-Channel LED Light Source for Fluorescent Agent Aided Minimally Invasive Surgery

    PubMed Central

    Ren, Jiacheng; Venugopalan, Janani; Xu, Jian; Kairdolf, Brad; Durfee, Robert; Wang, May D.

    2016-01-01

    Cancer is one of the most common and deadly diseases around the world. Amongst all the different treatments of cancer such as surgery, chemotherapy and radiation therapy, surgical resection is the most effective. Successful surgeries greatly rely on the detection of the accurate tumor size and location, which can be enhanced by contrast agents. Commercial endoscope light sources, however, offer only white light illumination. In this paper, we present the development of a LED endoscope light source that provides 2 light channels plus white light to help surgeons to detect a clear tumor margin during minimally invasive surgeries. By exciting indocyanine green (ICG) and 5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX), the light source is intended to give the user a visible image of the tumor margin. This light source is also portable, easy to use and costs less than $300 to build. PMID:25571589

  1. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light

    PubMed Central

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m−2⋅s−1 irradiance for a 16 h⋅d−1 photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (Amax) and photosynthetic rate (Pn) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. Pn and Amax under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between Pn and shoot dry weight accumulation. PMID:27014285

  2. Fibre coupled micro-light emitting diode array light source with integrated band-pass filter for fluorescence detection in miniaturised analytical systems.

    PubMed

    Vaculovičová, Markéta; Akther, Mahbub; Maaskant, Pleun; Brabazon, Dermot; Macka, Mirek

    2015-04-29

    In this work, a new type of miniaturized fibre-coupled solid-state light source is demonstrated as an excitation source for fluorescence detection in capillary electrophoresis. It is based on a parabolically shaped micro-light emitting diode (μ-LED) array with a custom band-pass optical interference filter (IF) deposited at the back of the LED substrate. The GaN μ-LED array consisted of 270 individual μ-LED elements with a peak emission at 470 nm, each about 14 μm in diameter and operated as a single unit. Light was extracted through the transparent substrate material, and coupled to an optical fibre (OF, 400 μm in diameter, numerical aperture NA=0.37), to form an integrated μ-LED-IF-OF light source component. This packaged μ-LED-IF-OF light source emitted approximately 225 μW of optical power at a bias current of 20 mA. The bandpass IF filter was designed to reduce undesirable LED light emissions in the wavelength range above 490 nm. Devices with and without IF were compared in terms of the optical power output, spectral characteristics as well as LOD values. While the IF consisted of only 7.5 pairs (15 layers) of SiO2/HfO2 layers, it resulted in an improvement of the baseline noise as well as the detection limit measured using fluorescein as test analyte, both by approximately one order of magnitude, with a LOD of 1×10(-8) mol L(-1) obtained under optimised conditions. The μ-LED-IF-OF light source was then demonstrated for use in capillary electrophoresis with fluorimetric detection. The limits of detection obtained by this device were compared to those obtained with a commercial fibre coupled LED device. PMID:25847165

  3. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light.

    PubMed

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation. PMID:27014285

  4. Improving efficiency roll-off in organic light emitting devices with a fluorescence-interlayer-phosphorescence emission architecture

    NASA Astrophysics Data System (ADS)

    Zheng, Tianhang; Choy, Wallace C. H.; Ho, Cheuk-Lam; Wong, Wai-Yeung

    2009-09-01

    Organic light emitting devices (OLEDs) with a fluorescence-interlayer-phosphorescence emission layer structure (FIP EML) has been proposed to solve the efficiency roll-off issue effectively. Efficient green OLED based on FIP EML exhibiting only 26% roll-off in the luminance efficiency, which is lower than the typical roll-off of 51% for conventional phosphorescent OLEDs with single EML operated at 5-150 mA/cm2 range, has been demonstrated. Such enhancement should be attributed to the improved carrier balance, the exciton redistribution in recombination zone, the suppression of nonradiative exciton quenching processes, and the elimination of energy transfer loss offered by the FIP EML structure.

  5. Magnetic field effects in singlet-polaron quenching in molecularly doped fluorescence organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Xu, Kai; Ma, Dongge

    2014-08-01

    The magnetic field effects of electroluminescence (MEL) in 4-[dicyanomethylene]-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) doped tri-(8-hydroxyquinoline)-aluminum (Alq3) based organic light-emitting diodes were investigated. A linear decrease in MEL with the increase of magnetic field was observed at high magnetic field (>20 mT) in this doping devices, which has been attributed to the singlet-polaron quenching effect. It was found that the singlet-polaron quenching is magnetic field dependent. Our results showed that singlet-polaron quenching commonly exists in fluorescence OLEDs and induces the linear decrease in MEL.

  6. Mass-independent fractionation of mercury isotopes in compact fluorescent light bulbs

    NASA Astrophysics Data System (ADS)

    Mead, C.; Anbar, A. D.; Lyons, J. R.; Johnson, T. M.

    2010-12-01

    Compact fluorescent lightbulbs (CFLs) are a growing source of Hg pollution. The high-energy environment of the CFLs combined with the known partitioning of Hg into the bulb walls could provide an environment for unusual isotope fractionation that could be used to trace pollution from improper bulb disposal. To investigate this possibility, we analyzed the isotope composition of Hg in CFL glass, phosphor powder, and whole bulbs from CFLs of known ages. We observed large, mass-independent fractionation of Hg isotopes between Hg embedded in the bulb wall and Hg in the liquid and vapor phases, which are the initial reservoir of Hg in the bulb. This fractionation results in the bulb wall showing enrichment of 198Hg, 199Hg, 200Hg, 201Hg, and 204Hg relative to 202Hg, the most abundant isotope. Both the amount of Hg embedded in the glass and the magnitude of the isotope enrichment were found to increase with the number of hours of light bulb use. For a CFL used for 3600 hours (with a rated lifetime of 10,000 hours), the isotopic composition of the Hg in the glass was enriched by 34.5‰, 4.1‰, 6.3‰, 21.1‰, and 12.1‰ for 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg, and 204Hg/202Hg, respectively, compared to NIST SRM-3133. This pattern of isotope enrichments is not correlated with mass differences for any of the isotope ratios. In contrast, the other mass-independent effects that have recently been observed in Hg isotopes (i.e., the nuclear volume and magnetic isotope effects) resemble mass-dependent fractionation for the even mass isotopes and are anomalous only for the odd mass isotopes, 199Hg and 201Hg. First order theoretical calculations using Hg absorption and emission data for each of the hyperfine components of the 253.7 nm line have shown that similar fractionation can be produced through an optical self-shielding effect. This effect occurs because each Hg isotope has a different degree of optical saturation at their respective absorption wavelength

  7. Performance of Introducing Outdoor Cold Air for Cooling a Plant Production System with Artificial Light

    PubMed Central

    Wang, Jun; Tong, Yuxin; Yang, Qichang; Xin, Min

    2016-01-01

    The commercial use of a plant production system with artificial light (PPAL) is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15–35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W) was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m2 each) was maintained at 25 and 20°C during photoperiod and dark period, respectively, for lettuce production. A null CO2 balance enrichment method was used in both PPALs. In one PPAL (PPALe), an air exchanger (air flow rate: 250 m3·h−1) was used along with a heat pump (cooling capacity: 3.2 kW) to maintain the indoor air temperature at the set-point. The other PPAL (PPALc) with only a heat pump (cooling capacity: 3.2 kW) was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP), electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2 to 30.0°C: (1) the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; (2) hourly electric-energy consumption for cooling in the PPALe reduced by 15.8–73.7% compared with that in the PPALc; (3) daily supply of CO2 in the PPALe reduced from 0.15 to 0.04 kg compared with that in the PPALc with the outdoor air temperature ranging from −5.6 to 2.7°C; (4) no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL. PMID:27066012

  8. Performance of Introducing Outdoor Cold Air for Cooling a Plant Production System with Artificial Light.

    PubMed

    Wang, Jun; Tong, Yuxin; Yang, Qichang; Xin, Min

    2016-01-01

    The commercial use of a plant production system with artificial light (PPAL) is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15-35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W) was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m(2) each) was maintained at 25 and 20°C during photoperiod and dark period, respectively, for lettuce production. A null CO2 balance enrichment method was used in both PPALs. In one PPAL (PPALe), an air exchanger (air flow rate: 250 m(3)·h(-1)) was used along with a heat pump (cooling capacity: 3.2 kW) to maintain the indoor air temperature at the set-point. The other PPAL (PPALc) with only a heat pump (cooling capacity: 3.2 kW) was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP), electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2 to 30.0°C: (1) the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; (2) hourly electric-energy consumption for cooling in the PPALe reduced by 15.8-73.7% compared with that in the PPALc; (3) daily supply of CO2 in the PPALe reduced from 0.15 to 0.04 kg compared with that in the PPALc with the outdoor air temperature ranging from -5.6 to 2.7°C; (4) no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL. PMID:27066012

  9. Dynamic response of plant chlorophyll fluorescence to light, water and nutrient availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water deficit limits net photosynthesis (Anet) and decreases crop yields. An important challenge for basic and applied research is to establish a rigorous landscape-scale indicator of Anet. Chlorophyll fluorescence (ChF) can be used at the field scale as an indirect measure of Anet in both healthy a...

  10. Fluorescent Proteins as Biomarkers and Biosensors: Throwing Color Lights on Molecular and Cellular Processes

    PubMed Central

    Stepanenko, Olesya V.; Verkhusha, Vladislav V.; Kuznetsova, Irina M.; Uversky, Vladimir N.; Turoverov, K.K.

    2010-01-01

    Green fluorescent protein (GFP) from jellyfish Aequorea victoria is the most extensively studied and widely used in cell biology protein. GFP-like proteins constitute a fast growing family as several naturally occurring GFP-like proteins have been discovered and enhanced mutants of Aequorea GFP have been created. These mutants differ from wild-type GFP by conformational stability, quantum yield, spectroscopic properties (positions of absorption and fluorescence spectra) and by photochemical properties. GFP-like proteins are very diverse, as they can be not only green, but also blue, orange-red, far-red, cyan, and yellow. They also can have dual-color fluorescence (e.g., green and red) or be non-fluorescent. Some of them possess kindling property, some are photoactivatable, and some are photoswitchable. This review is an attempt to characterize the main color groups of GFP-like proteins, describe their structure and mechanisms of chromophore formation, systemize data on their conformational stability and summarize the main trends of their utilization as markers and biosensors in cell and molecular biology. PMID:18691124

  11. Real-time endoscopic guidance using near-infrared fluorescent light for thoracic surgery

    NASA Astrophysics Data System (ADS)

    Venugopal, Vivek; Stockdale, Alan; Neacsu, Florin; Kettenring, Frank; Frangioni, John V.; Gangadharan, Sidharta P.; Gioux, Sylvain

    2013-03-01

    Lung cancer is the leading cause of cancer death in the United States, accounting for 28% of all cancer deaths. Standard of care for potentially curable lung cancer involves preoperative radiographic or invasive staging, followed by surgical resection. With recent adjuvant chemotherapy and radiation studies showing a survival advantage in nodepositive patients, it is crucial to accurately stage these patients surgically in order to identify those who may benefit. However, lymphadenectomy in lung cancer is currently performed without guidance, mainly due to the lack of tools permitting real-time, intraoperative identification of lymph nodes. In this study we report the design and validation of a novel, clinically compatible near-infrared (NIR) fluorescence thoracoscope for real-time intraoperative guidance during lymphadenectomy. A novel, NIR-compatible, clinical rigid endoscope has been designed and fabricated, and coupled to a custom source and a dual channel camera to provide simultaneous color and NIR fluorescence information to the surgeon. The device has been successfully used in conjunction with a safe, FDA-approved fluorescent tracer to detect and resect mediastinal lymph nodes during thoracic surgery on Yorkshire pigs. Taken together, this study lays the foundation for the clinical translation of endoscopic NIR fluorescence intraoperative guidance and has the potential to profoundly impact the management of lung cancer patients.

  12. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  13. Subtle spectral effects accompanying the assembly of bacteriochlorophylls into cyclic light harvesting complexes revealed by high-resolution fluorescence spectroscopy

    SciTech Connect

    Rätsep, Margus Pajusalu, Mihkel Linnanto, Juha Matti; Freiberg, Arvi

    2014-10-21

    We have observed that an assembly of the bacteriochloropyll a molecules into B850 and B875 groups of cyclic bacterial light-harvesting complexes LH2 and LH1, respectively, results an almost total loss of the intra-molecular vibronic structure in the fluorescence spectrum, and simultaneously, an essential enhancement of its phonon sideband due to electron-phonon coupling. While the suppression of the vibronic coupling in delocalized (excitonic) molecular systems is predictable, as also confirmed by our model calculations, a boost of the electron-phonon coupling is rather unexpected. The latter phenomenon is explained by exciton self-trapping, promoted by mixing the molecular exciton states with charge transfer states between the adjacent chromophores in the tightly packed B850 and B875 arrangements. Similar, although less dramatic trends were noted for the light-harvesting complexes containing chlorophyll pigments.

  14. Identification of two quenching sites active in the regulation of photosynthetic light-harvesting studied by time-resolved fluorescence

    NASA Astrophysics Data System (ADS)

    Holzwarth, Alfred R.; Miloslavina, Yuliya; Nilkens, Manuela; Jahns, Peter

    2009-12-01

    The regulation of light-harvesting (called non-photochemical quenching, NPQ) is an essential photoprotective mechanism active in plants. Total NPQ is dependent on PsbS, a pH-sensing protein, and on the action of the xanthophyll carotenoid zeaxanthin (Zx). Using ultrafast fluorescence on intact leaves we demonstrate two independent NPQ quenching sites in vivo which depend differently on the actions of PsbS and Zx. The first site is formed in the functionally detached major light-harvesting complex of PS II and depends strictly on PsbS. The second site is in the minor antennae of photosystem (PS) II and quenching depends on the presence of Zx.

  15. Promising operational stability of high-efficiency organic light-emitting diodes based on thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Nakanotani, Hajime; Masui, Kensuke; Nishide, Junichi; Shibata, Takumi; Adachi, Chihaya

    2013-07-01

    Organic light-emitting diodes (OLEDs) are attractive for next-generation displays and lighting applications because of their potential for high electroluminescence (EL) efficiency, flexibility and low-cost manufacture. Although phosphorescent emitters containing rare metals such as iridium or platinum produce devices with high EL efficiency, these metals are expensive and their blue emission remains unreliable for practical applications. Recently, a new route to high EL efficiency using materials that emit through thermally activated delayed fluorescence (TADF) was demonstrated. However, it is unclear whether devices that emit through TADF, which originates from the contributions of triplet excitons, are reliable. Here we demonstrate highly efficient, stable OLEDs that emit via TADF by controlling the position of the carrier recombination zone, resulting in projected lifetimes comparable to those of tris(2-phenylpyridinato)iridium(III)-based reference OLEDs. Our results indicate that TADF is intrinsically stable under electrical excitation and optimization of the surrounding materials will enhance device reliability.

  16. Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy.

    PubMed

    Höhn, K; Fuchs, J; Fröber, A; Kirmse, R; Glass, B; Anders-Össwein, M; Walther, P; Kräusslich, H-G; Dietrich, C

    2015-08-01

    In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV-pulsed mature human dendritic cells. PMID:25786567

  17. Detection system of acid rain pollution using light-induced delayed fluorescence of plant leaf in vivo

    NASA Astrophysics Data System (ADS)

    Zeng, Lizhang; Xing, Da

    2006-09-01

    Photosynthetic apparatus is susceptible to environmental stress. Light-induced delayed fluorescence (DF) in plant is an intrinsic label of the efficiency of charge separation at P680 in photosystem II (PS II). In this investigation, we have developed a biosensor that can accurately inspect acid rain pollution by means of DF in vivo. Compared with traditional methods, the proposed technique can continuously monitor environmental changes, making fast, real-time and noninvasive inspection possible. The biosensor is an all-weather measuring instrument; it has its own illumination power and utilizes intrinsic DF as the measurement marker. With soybean (Glycine max (L.) Merr.) seedling as a testing model, which is sensitive to acid rain pollution, the relationship that delayed fluorescence properties and capability of photosynthetic apparatus after being affected by simulated acid rain with different pH value was studied. The current investigation has revealed that the changes of delayed fluorescence (equation available in paper) can probably characterize the pollution degree of simulated acid rain, Inspecting the changes in DF characteristics (φ i) of plant leaf in vivo may be a new approach for the detection of acid rain pollution and its impact on the ecosystem.

  18. Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy

    PubMed Central

    HÖHN, K.; FUCHS, J.; FRÖBER, A.; KIRMSE, R.; GLASS, B.; ANDERS‐ÖSSWEIN, M.; WALTHER, P.; KRÄUSSLICH, H.‐G.

    2015-01-01

    Summary In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV‐pulsed mature human dendritic cells. PMID:25786567

  19. Rewiring Multidomain Protein Switches: Transforming a Fluorescent Zn(2+) Sensor into a Light-Responsive Zn(2+) Binding Protein.

    PubMed

    Aper, Stijn J A; Merkx, Maarten

    2016-07-15

    Protein-based sensors and switches provide attractive tools for the real-time monitoring and control of molecular processes in complex biological environments. Fluorescent sensor proteins have been developed for a wide variety of small molecules, but the construction of genetically encoded light-responsive ligand binding proteins remains mostly unexplored. Here we present a generic approach to reengineer a previously developed FRET-based Zn(2+) sensor into a light-activatable Zn(2+) binding protein using a design strategy based on mutually exclusive domain interactions. These so-called VividZn proteins consist of two light-responsive Vivid domains that homodimerize upon illumination with blue light, thus preventing the binding of Zn(2+) between two Zn(2+) binding domains, Atox1 and WD4. Following optimization of the linker between WD4 and the N-terminus of one of the Vivid domains, VividZn variants were obtained that show a 9- to 55-fold decrease in Zn(2+) affinity upon illumination, which is fully reversible following dark adaptation. The Zn(2+) affinities of the switch could be rationally tuned between 1 pM and 2 nM by systematic variation of linker length and mutation of one of the Zn(2+) binding residues. Similarly, introduction of mutations in the Vivid domains allowed tuning of the switching kinetics between 10 min and 7 h. Low expression levels in mammalian cells precluded the demonstration of light-induced perturbation of cytosolic Zn(2+) levels. Nonetheless, our results firmly establish the use of intramolecular Vivid dimerization as an attractive light-sensitive input module to rationally engineer light-responsive protein switches based on mutually exclusive domain interactions. PMID:27031076

  20. The Effects on Visually Impaired Children of Viewing Fluorescent Stimuli under Black-Light Conditions.

    ERIC Educational Resources Information Center

    LaGrow, S. J.; Leung, J-P.; Leung, S.; Yeung, P.

    1998-01-01

    This study compared effects of four visual conditions of stimuli and light on the visual performance of 30 children with low vision (divided into high, and low, visual-acuity groups). Orange stimuli viewed under black light resulted in the best overall performance, benefitted the low-acuity group more than the high-acuity group, and was the…

  1. OWL-Orbital Wide-angle Light-collector for the air watch program, and multiple OWL

    NASA Astrophysics Data System (ADS)

    Ebisuzaki, Toshikazu; Takahashi, Yoshiyuki; Mohri, Mamoru; Dimmock, John O.; Hillman, Lloyd W.; Hadaway, James B.; Lamb, David J.; Handa, Toshihiro

    2000-01-01

    The International Space Station (ISS) will revolutionize scientific experimentation by providing a platform upon which some of the most ambitious projects yet conceived may be constructed, operated, and deployed. The Orbiting Wide-angle Light-collector (OWL-Airwatch) is a proposed space-based extensive air shower observatory which will detect a significant number of cosmic rays with energies above 1020 eV (Takahashi, 1996; Streitmatter, 1998; DeMarzo, 1998). A complete understanding of the origins and propagation of these particles may only be possible by introducing new and exotic physical mechanisms, and OWL-Airwatch may provide the first definitive evidence for the existence and decay of topological defects and other such exotic phenomena. There also exists the possibility of detecting high energy neutrinos as well as observing the effects of quantum gravity with the OWL-Airwatch instrument. Although the first OWL-Airwatch mission is planned as a free-flying observatory, its scientific abilities can be greatly enhanced by moving to a so-called multi-OWL configuration with the resources available on the ISS. The current OWL-Airwatch mission will observe nitrogen fluorescence resulting from cosmic ray induced extensive air showers in the earth's atmosphere. Observing from space enables a large enough portion of the earth to be viewed such that a statistically significant number of the rare highest energy events can be detected within the life span of the mission. A second phase multi-OWL system fabricated and assembled on the ISS would further increase the threshold and statistics of the OWL-Airwatch mission. In this scheme, as many as seven OWL-Airwatch instruments would be assembled and deployed from the ISS. These seven units would cover the entire horizon of the earth's atmosphere at an orbit of 1000 km and would accurately map the cosmic ray spectrum beyond 1021 eV. .

  2. Genetically Encoded Optochemical Probes for Simultaneous Fluorescence Reporting and Light Activation of Protein Function with Two-Photon Excitation

    PubMed Central

    2014-01-01

    The site-specific incorporation of three new coumarin lysine analogues into proteins was achieved in bacterial and mammalian cells using an engineered pyrrolysyl-tRNA synthetase system. The genetically encoded coumarin lysines were successfully applied as fluorescent cellular probes for protein localization and for the optical activation of protein function. As a proof-of-principle, photoregulation of firefly luciferase was achieved in live cells by caging a key lysine residue, and excellent OFF to ON light-switching ratios were observed. Furthermore, two-photon and single-photon optochemical control of EGFP maturation was demonstrated, enabling the use of different, potentially orthogonal excitation wavelengths (365, 405, and 760 nm) for the sequential activation of protein function in live cells. These results demonstrate that coumarin lysines are a new and valuable class of optical probes that can be used for the investigation and regulation of protein structure, dynamics, function, and localization in live cells. The small size of coumarin, the site-specific incorporation, the application as both a light-activated caging group and as a fluorescent probe, and the broad range of excitation wavelengths are advantageous over other genetically encoded photocontrol systems and provide a precise and multifunctional tool for cellular biology. PMID:25341086

  3. Postcolumn reactor using a laser-drilled capillary for light-emitting diode-induced fluorescence detection in CE.

    PubMed

    Yamamoto, Daisuke; Kaneta, Takashi; Imasaka, Totaro

    2007-11-01

    This study investigated a novel postcolumn reactor for fluorescence detection in CE. A laser-drilled capillary, with an aperture made by laser ablation, was used for mixing derivatization reagents with the analytes separated by CZE. The derivatization reagents, o-phthaldialdehyde (OPA), and 2-mercaptoethanol, were introduced into the capillary through the aperture and reacted with the analytes after CZE separation. High voltages were applied to both the inlet reservoir and the reservoir filled with the derivatization reagents. Thus, the flow rate of the derivatization reagents was controlled by the electric potential that was applied to the reservoir of the derivatization reagents. A UV light-emitting diode was used as an excitation light source for the fluorescence detection of OPA derivatives. A commercially available tee connector was compared with the laser-drilled capillary. The results implied that the dead volume of the laser-drilled capillary was less than that of the tee connector, since the laser-drilled capillary suppressed band broadening more efficiently. The LODs for amino acids were determined to be approximately 5 microM. The method was applied to the determination of amino acids in a Japanese beverage. PMID:17948271

  4. A facile light-emitting-diode induced fluorescence detector coupled to an integrated microfluidic device for microchip electrophoresis.

    PubMed

    Yang, Fan; Li, Xin-chun; Zhang, Wen; Pan, Jian-bin; Chen, Zuan-guang

    2011-05-30

    In this paper, a compact and inexpensive light emitting diode induced fluorescence (LED-IF) detector with simplified optical configuration was developed and assembled in an integrated microfluidic device for microscale electrophoresis. The facile detector mainly consisted of an LED, a focusing pinhole, an emission filter and a photodiode, and was encapsulated in the upper layer of an aluminum alloy device with two layers. At the bottom layer, integrated circuit (IC) was assembled to manipulate the voltage for sample injection and separation, LED emission and signal amplifying. A high-power LED with fan-shaped heat sink was used as excitation source. The excitation light was focused by a 1.1mm diameter pinhole fabricated in a thin piece of silver foil, and the obtained sensitivity was about 3 times as high as that using electrode plate. Other important parameters including LED driven current, fluorescence collection angle and detection distance have also been investigated. Under optimal conditions, considerable high-response of 0.09 fmol and 0.18 fmol mass detection limits at 0.37 nL injection volume for sodium fluorescein (SF) and FITC was achieved, respectively. This device has been successfully employed to separate penicillamine (PA) enantiomers. Due to such significant features as low-cost, integration, miniaturization, and ease of commercialization, the presented microfluidic device may hold great promise for clinical diagnostics and bioanalytical applications. PMID:21530784

  5. Thermally Activated Delayed Fluorescence Polymers for Efficient Solution-Processed Organic Light-Emitting Diodes.

    PubMed

    Lee, Sae Youn; Yasuda, Takuma; Komiyama, Hideaki; Lee, Jiyoung; Adachi, Chihaya

    2016-06-01

    Thermally activated delayed fluorescence (TADF) π-conjugated polymers are developed for solution-processed TADF-OLEDs. Benzophenone-based alternating donor-acceptor structures contribute to the small ∆EST , enabling efficient exciton-harvesting through TADF. Solution-processed OLEDs using the TADF polymers as emitters can achieve high maximum external electroluminescence efficiencies of up to 9.3%. PMID:27001891

  6. Green fluorescent protein: new light to visualize metastasis and angiogenesis in cancer

    NASA Astrophysics Data System (ADS)

    Yang, Meng; Chishima, Takashi; Baranov, Eugene; Shimada, Hiroshi; Moossa, A. R.; Hoffman, Robert M.

    1999-07-01

    Green fluorescent protein (GFP)-expressing cell-lines have been established by our laboratory that permit the visualization and imaging of primary tumors and micrometastases in live tissue and live animals. Hamster and human cancer cell-lines were transfected with vectors containing the humanized GFP cDNA. Stable high-level expression of GFP was maintained in subcutaneously and orthotopically growing tumors in nude or SCID mice. Subsequent micro-metastases were visualized by GFP fluorescence in live tissue of systematic organs down to the single-cell level. GFP-expressing lung and prostate cancer were visualized to metastasize widely throughout the skeleton when implanted orthotopically in nude mice. With these GFP-cell lines, we have developed models that closely mimic the clinic situation. We have now developed a mean to visualize the onset and progression of angiogenesis of growing and spreading tumors by injecting a fluorescent rhodamine dye to the GFP-tumor-bearing mice indicate that the onset and extent of tumor angiogenesis depends on the site and type of tumor growing in the animal. These models are ideal for studying the mechanisms of cancer metastasis and for discovery of angiogenesis and metastasis inhibitors.

  7. Light emitting diode, photodiode-based fluorescence detection system for DNA analysis with microchip electrophoresis.

    PubMed

    Hall, Gordon H; Glerum, D Moira; Backhouse, Christopher J

    2016-02-01

    Electrophoretic separation of fluorescently end-labeled DNA after a PCR serves as a gold standard in genetic diagnostics. Because of their size and cost, instruments for this type of analysis have had limited market uptake, particularly for point-of-care applications. This might be changed through a higher level of system integration and lower instrument costs that can be realized through the use of LEDs for excitation and photodiodes for detection--if they provide sufficient sensitivity. Here, we demonstrate an optimized microchip electrophoresis instrument using polymeric fluidic chips with fluorescence detection of end-labeled DNA with a LOD of 0.15 nM of Alexa Fluor 532. This represents orders of magnitude improvement over previously reported instruments of this type. We demonstrate the system with an electrophoretic separation of two PCR products and their respective primers. We believe that this is the first LED-induced fluorescence microchip electrophoresis system with photodiode-based detection that could be used for standard applications of PCR and electrophoresis. PMID:26412502

  8. Resonance fluorescence spectra from coherently driven quantum dots coupled to slow-light photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Roy-Choudhury, Kaushik; Mann, Nishan; Manson, Ross; Hughes, Stephen

    2016-06-01

    Using a polaron master equation approach, we investigate the resonance fluorescence spectra from coherently driven quantum dots (QDs) coupled to an acoustic phonon bath and photonic crystal waveguides with a rich local density of photon states (LDOS). Resonance fluorescence spectra from QDs in semiconductor crystals are known to show strong signatures of electron-phonon interactions, but when coupled to a structured photonic reservoir, the QD emission properties are also determined by the frequency dependence of the LDOS of the photon reservoir. Here, we investigate the simultaneous role of coupled photon and phonon baths on the characteristic Mollow triplet spectra from a strongly driven QD. As an example structured photonic reservoir, we first study a photonic crystal coupled cavity waveguide, and find that photons and phonons have counterinteracting effects near the upper mode edge of the coupled-cavity waveguide, thus establishing the importance of their separate roles in determining the emission spectra. The general theory is developed for arbitrary photonic reservoirs and is further applied to determine the resonance fluorescence spectra from a realistic, disordered W1 photonic crystal waveguide showing important photon-phonon interaction effects that are directly relevant to emerging experiments and theoretical proposals.

  9. Chlorophyll fluorescence and the polarized underwater light field: comparison of vector radiative transfer simulations and multi-angular hyperspectral polarization field measurements

    NASA Astrophysics Data System (ADS)

    El-habashi, Ahmed; Ahmed, Samir

    2016-05-01

    Previous partial simulations and field measurements by us, had demonstrated the impact of the un-polarized nature of algal chlorophyll fluorescence to reduce the observed degree of polarization of the underwater light field in the spectral vicinity of fluorescence. (Polarization otherwise existing as a result of non-algal particulate (NAP) and molecular elastic scattering). The magnitude of this fluorescence driven dip in the observed degree of polarization was also seen to be theoretically related to the fluorescence magnitude. The recent availability to us of the RayXP vector radiative transfer code (VRTE) for the coupled atmosphere ocean system now permits us to make complete simulations of the underwater polarized light field, using measured inherent optical properties (IOPs) as inputs. Based on these simulations, a much more comprehensive analysis of the fluorescence impact is now possible. Combining the results of these new simulations with underwater field measurements in eutrophic waters using our hyperspectral multi angle polarimeter, we verified the theoretical relationship. In addition, comparisons of VRTE simulations and hyperspectral polarized field measurements for various coastal water conditions permit retrieval of fluorescence magnitudes. Comparisons of these polarization based fluorescence retrievals with retrievals obtained using fluorescence height over baseline or Hydrolight scalar simulations, together with total unpolarized radiance measurements, show good agreement.

  10. Two-photon light-sheet nanoscopy by fluorescence fluctuation correlation analysis

    NASA Astrophysics Data System (ADS)

    Chen, Xuanze; Zong, Weijian; Li, Rongqin; Zeng, Zhiping; Zhao, Jia; Xi, Peng; Chen, Liangyi; Sun, Yujie

    2016-05-01

    Advances in light-sheet microscopy have enabled the fast three-dimensional (3D) imaging of live cells and bulk specimens with low photodamage and phototoxicity. Combining light-sheet illumination with super-resolution imaging is expected to resolve subcellular structures. Actually, such kind of super-resolution light-sheet microscopy was recently demonstrated using a single-molecule localization algorithm. However, the imaging depth and temporal resolution of this method are limited owing to the requirements of precise single molecule localization and reconstruction. In this work, we present two-photon super-resolution light-sheet imaging via stochastic optical fluctuation imaging (2PLS-SOFI), which acquires high spatiotemporal resolution and excellent optical sectioning ability. 2PLS-SOFI is based on non-linear excitation of fluctuation/blinking probes using our recently developed fast two-photon three-axis digital scanned light-sheet microscope (2P3A-DSLM), which enables both deep penetration and thin sheet of light. Overall, 2PLS-SOFI demonstrates up to 3-fold spatial resolution enhancement compared with conventional two-photon light-sheet (2PLS) microscopy and about 40-fold temporal resolution enhancement compared with individual molecule localization-selective plane illumination microscopy (IML-SPIM). Therefore, 2PLS-SOFI is promising for 3D long-term, deep-tissue imaging with high spatiotemporal resolution.

  11. Two-photon light-sheet nanoscopy by fluorescence fluctuation correlation analysis.

    PubMed

    Chen, Xuanze; Zong, Weijian; Li, Rongqin; Zeng, Zhiping; Zhao, Jia; Xi, Peng; Chen, Liangyi; Sun, Yujie

    2016-05-21

    Advances in light-sheet microscopy have enabled the fast three-dimensional (3D) imaging of live cells and bulk specimens with low photodamage and phototoxicity. Combining light-sheet illumination with super-resolution imaging is expected to resolve subcellular structures. Actually, such kind of super-resolution light-sheet microscopy was recently demonstrated using a single-molecule localization algorithm. However, the imaging depth and temporal resolution of this method are limited owing to the requirements of precise single molecule localization and reconstruction. In this work, we present two-photon super-resolution light-sheet imaging via stochastic optical fluctuation imaging (2PLS-SOFI), which acquires high spatiotemporal resolution and excellent optical sectioning ability. 2PLS-SOFI is based on non-linear excitation of fluctuation/blinking probes using our recently developed fast two-photon three-axis digital scanned light-sheet microscope (2P3A-DSLM), which enables both deep penetration and thin sheet of light. Overall, 2PLS-SOFI demonstrates up to 3-fold spatial resolution enhancement compared with conventional two-photon light-sheet (2PLS) microscopy and about 40-fold temporal resolution enhancement compared with individual molecule localization-selective plane illumination microscopy (IML-SPIM). Therefore, 2PLS-SOFI is promising for 3D long-term, deep-tissue imaging with high spatiotemporal resolution. PMID:27121341

  12. Prediction and design of efficient exciplex emitters for high-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes.

    PubMed

    Liu, Xiao-Ke; Chen, Zhan; Zheng, Cai-Jun; Liu, Chuan-Lin; Lee, Chun-Sing; Li, Fan; Ou, Xue-Mei; Zhang, Xiao-Hong

    2015-04-01

    High-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes based on exciplex emitters are demonstrated. The best device, based on a TAPC:DPTPCz emitter, shows a high external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex emitters are also provided. This approach allow prediction and design of efficient exciplex emitters for achieving high-efficiency organic light-emitting diodes, for future use in displays and lighting applications. PMID:25712786

  13. Daytime Cognitive Performance in Response to Sunlight or Fluorescent Light Controlling for Sleep Duration

    NASA Technical Reports Server (NTRS)

    Ramos, Jhanic; Zamos, Adela; Rao, Rohit; Flynn-Evans, Erin

    2015-01-01

    Light is the primary synchronizer of the human circadian rhythm and also has acute alerting effects. Our study involves and comparing the alertness, performance and sleep of participants in the NASA Ames Sustainability Base, which uses sunlight as its primary light source, to in a traditional office building which uses overhead florescent lighting and varying exposure to natural light. The purpose of this study is to determine whether the use of natural lighting as a primary light source improves daytime cognitive function and promotes nighttime sleep. Participants from the Sustainability Base will be matched by gender and age to individuals working in other NASA buildings. In a prior study we found no differences in performance between those working in the Sustainability Base and those working in other buildings. Unexpectedly, we found that the average sleep duration among participants in both buildings was short, which likely obscured our ability to detect a difference the effect of light exposure on alertness. Given that such sleep deprivation has negative effects on cognitive performance, in this iteration of the study we are asking the participants to maintain a regular schedule with eight hours in bed each night in order to control for the effect of self-selected sleep restriction. Over the course of one week, we will ask the participants to wear actiwatches continuously, complete a psychomotor vigilance task (PVT) and digit symbol substitution task (DSST) three times per day, and keep daily sleepwork diaries. We hope that this study will provide data to support the idea that natural lighting and green architectural design are optimal to enhance healthy nighttime sleep patterns and daytime cognitive performance.

  14. Technologies for Maintaining Animals in Space: Lighting, Air Quality, Noise, Food and Water

    NASA Technical Reports Server (NTRS)

    Winget, C. M.; Skidmore, M. G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1995-01-01

    In the terrestrial environment multiple time cues exist. Zeitgebers have been identified and studied for their ability to convey temporal information to various physiological systems, In the microgravity experiment it is necessary to define time cues within the flight hardware prior to flight. During flight if changes in the Circadian System (e.g., mean, phase angle, period) occur this would indicate that the gravity vector is important relative to biological timing. This presentation is concerned with the environmental parameters to support rodent experiments in microgravity. The Animal Enclosure Module (AEM) provides solid food bars and water via lixits ad libitum. Flight animals (Sprague-Dawley rats, 60 - 300g) when compared to ground controls show similar growth (mean growth per day, g +/- SD; flight 5.4 +/- 2.0, ground 5.9 +/- 2.1). Current AEMs use incandescent lighting (approx. 5 Lux). Light emitting diode (LED) arrays are being developed that provide a similar light environment as cool-white fluorescent sources (40 Lux). In ground based tests (12L:12D), these arrays show normal circadian entrainment (Tau = 24.0) with respect to the behavioral responses. measured (drinking, eating, gross locomotor activity). A newly developed ultra high efficiency filter system can entrap all feces, urine and odors from 6 rats for 24 days. Maximum sound level exposure limits (per octave band 22 Hz - 179 kHz) have been established. The AEM will effectively support animal experiments in microgravity.

  15. Technologies For Maintaining Animals In Space: Lighting, Air Quality, Noise, Food And Water

    NASA Technical Reports Server (NTRS)

    Winget, C. M.; Skidmore, M. G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1995-01-01

    In the terrestrial environment multiple time cues exist. Zeitgebers have been identified and studied for their ability to convey temporal information to various physiological systems. In the microgravity experiment it is necessary to define time cues within the flight hardware prior to flight. During flight if changes in the Circadian System (e.g., mean, phase angle, period) occur this would indicate that the gravity vector is important relative to biological timing. This presentation is concerned with the environmental parameter: to support rodent experiments in microgravity. The Animal Enclosure Module (AEM) provides solid food bars and water via lixits and ad libitum. Flight animals (Sprague-Dawley rats, 60 - 300g) when compared to ground controls show similar growth (mean growth per day g, plus or minus SD; flight 5.4 plus or minus 2.0, ground 5.9 plus or minus 2.1). Current AEMs use incandescent lighting (approx. 5 Lux). Light emitting diode (LED) arrays are being developed that provide a similar light environment as cool-white fluorescent sources (40 Lux). In ground based tests (12L:12D), these arrays show normal circadian entrainment (Tau = 24.0) with respect to the behavioral responses, measured (drinking, eating, gross locomotor activity). A newly developed ultra high efficiency filter system can entrap all feces, urine and odors from 6 rats for 24 days. Maximum sound level exposure limits (per octave band 22 Hz - 179 kHz) have been established. The AEM will effectively support animal experiments in microgravity.

  16. Visible-Light-Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian; Richards, Jeffrey Todd

    2014-01-01

    Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. The development of a visible-light responsive (VLR) TiO2-based catalyst would eliminate the concerns over mercury contamination. Further, VLR development would allow for the use of ambient visible solar radiation or highly efficient LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts. Those VLR catalysts that are commercially available do not have adequate catalytic activity, in the visible region, to make them competitive with those operating under UV irradiation. This study was initiated to develop more effective VLR catalysts through a novel method in which quantum dots (QD) consisting of narrow band gap semiconductors (e.g., CdS, CdSe, PbS, ZnSe, etc.) are coupled to TiO2 via two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems and served as model contaminants for this research. Synthesized catalysts were compared in terms of

  17. Influence of the light-curing unit, storage time and shade of a dental composite resin on the fluorescence

    NASA Astrophysics Data System (ADS)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Gaiao, U.; Cuin, A.; Porto-Neto, S. T.

    2010-07-01

    The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 ± 0.1 mm, thickness 1.0 ± 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A2E, A2D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37°C and 100% humidity. The analysis of variance (ANOVA) and Tukey’s posthoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) ( P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage ( P < 0.05). The colors had difference significant between them (shades: A2D < A2E < TC) ( P < 0.05). The Ultraled (LED) and Ultralux (QTH) when used the TC shade showed higher than Radii (LED), however to A2E shade and A2D shade any difference were found ( P > 0.05).

  18. In-vacuum scattered light reduction with black cupric oxide surfaces for sensitive fluorescence detection.

    PubMed

    Norrgard, E B; Sitaraman, N; Barry, J F; McCarron, D J; Steinecker, M H; DeMille, D

    2016-05-01

    We demonstrate a simple and easy method for producing low-reflectivity surfaces that are ultra-high vacuum compatible, may be baked to high temperatures, and are easily applied even on complex surface geometries. Black cupric oxide (CuO) surfaces are chemically grown in minutes on any copper surface, allowing for low-cost, rapid prototyping, and production. The reflective properties are measured to be comparable to commercially available products for creating optically black surfaces. We describe a vacuum apparatus which uses multiple blackened copper surfaces for sensitive, low-background detection of molecules using laser-induced fluorescence. PMID:27250404

  19. Broadband Antireflection and Light Extraction Enhancement in Fluorescent SiC with Nanodome Structures

    PubMed Central

    Ou, Yiyu; Zhu, Xiaolong; Jokubavicius, Valdas; Yakimova, Rositza; Mortensen, N. Asger; Syväjärvi, Mikael; Xiao, Sanshui; Ou, Haiyan

    2014-01-01

    We demonstrate a time-efficient and low-cost approach to fabricate Si3N4 coated nanodome structures in fluorescent SiC. Nanosphere lithography is used as the nanopatterning method and SiC nanodome structures with Si3N4 coating are formed via dry etching and thin film deposition process. By using this method, a significant broadband surface antireflection and a considerable omnidirectional luminescence enhancement are obtained. The experimental observations are then supported by numerical simulations. It is believed that our fabrication method will be well suitable for large-scale production in the future. PMID:24722521

  20. Generation of UV light by intense ultrashort laser pulses in air

    NASA Astrophysics Data System (ADS)

    Alexeev, Ilya; Ting, Antonio; Gordon, Daniel; Briscoe, Eldridge; Penano, Joe; Sprangle, Phillip

    2004-11-01

    The propagation of collimated high-peak-power ultrashort laser pulses in air has attracted considerable attention, which may have a variety of important applications including remote sensing and chemical-biological aerosols standoff detection. Sub-millimeter diameter laser filaments can develop without any focusing optics and instead solely from laser self-focusing and plasma formation in air. These filaments can produce ultraviolet radiations in the form of the 3rd harmonic of the fundamental frequency and also through spectral broadening due to self-phase modulation of the laser pulse. Using femtosecond laser pulses produced by a high power Ti:Sapphire laser (0.8 TW, 50 fs, 800 nm) we observed generation of the third harmonic radiation light in air (centered around 267 nm) by the laser filaments. Characterization of the 3rd harmonic generation with respect to the major gas components of the air will be reported. Supported by the ONR and RDECOM. I. Alexeev is NRC/NRL Post-Doc.

  1. The influence of visible light and inorganic pigments on fluorescence excitation emission spectra of egg-, casein- and collagen-based painting media

    NASA Astrophysics Data System (ADS)

    Nevin, A.; Anglos, D.; Cather, S.; Burnstock, A.

    2008-07-01

    Spectrofluorimetric analysis of proteinaceous binding media is particularly promising because proteins employed in paintings are often fluorescent and media from different sources have significantly different fluorescence spectral profiles. Protein-based binding media derived from eggs, milk and animal tissue have been used for painting and for conservation, but their analysis using non-destructive techniques is complicated by interferences with pigments, their degradation and their low concentration. Changes in the fluorescence excitation emission spectra of films of binding media following artificial ageing to an equivalent of 50 and 100 years of museum lighting include the reduction of bands ascribed to tyrosine, tryptophan and Maillard reaction products and an increase in fluorescent photodegradation. Fluorescence of naturally aged paint is dependent on the nature of the pigment present and, with egg-based media, in comparison with un-pigmented films, emissions ascribed to amino acids are more pronounced.

  2. Improved light output power of LEDs with embedded air voids structure and SiO2 current blocking layer

    NASA Astrophysics Data System (ADS)

    Zhou, Shengjun; Yuan, Shu; Liu, Sheng; Ding, Han

    2014-06-01

    GaN-based light-emitting diodes (LEDs) with an embedded air voids structure and a SiO2 current blocking layer (CBL) was fabricated and investigated. The air voids structure was formed between cone-shaped patterned sapphire substrate and GaN epitaxial layer by combining laser scribing with H3PO4-based hot chemical etching. The air voids embedded high power LED showed 8.9% higher light output power due to a strong light reflection and redirection at the interface between GaN and air voids, which could increase the top light extraction of the high power LED. Compared to the air voids embedded high power LED, the light output power of the high power LED by integrating air voids structure with SiO2 CBL was 9.1% higher than that of the air voids embedded LED without SiO2 CBL. It was also found that the simulation results agree well with the experimental results.

  3. Ultracompact alignment-free single molecule fluorescence device with a foldable light path

    NASA Astrophysics Data System (ADS)

    Kumar Singh, Niraj; Chacko, Jenu V.; Sreenivasan, Varun K. A.; Nag, Suman; Maiti, Sudipta

    2011-02-01

    Instruments with single-molecule level detection capabilities can potentially benefit a wide variety of fields, including medical diagnostics. However, the size, cost, and complexity of such devices have prevented their widespread use outside sophisticated research laboratories. Fiber-only devices have recently been suggested as smaller and simpler alternatives, but thus far, they have lacked the resolution and sensitivity of a full-fledged system, and accurate alignment remains a critical requirement. Here we show that through-space reciprocal optical coupling between a fiber and a microscope objective, combined with wavelength division multiplexing in optical fibers, allows a drastic reduction of the size and complexity of such an instrument while retaining its resolution. We demonstrate a 4×4×18 cm3 sized fluorescence correlation spectrometer, which requires no alignment, can analyze kinetics at the single-molecule level, and has an optical resolution similar to that of much larger microscope based devices. The sensitivity can also be similar in principle, though in practice it is limited by the large background fluorescence of the commonly available optical fibers. We propose this as a portable and field deployable single molecule device with practical diagnostic applications.

  4. Trimodal detection of early childhood caries using laser light scanning and fluorescence spectroscopy: clinical prototype

    PubMed Central

    Kim, Amy S.; Ridge, Jeremy S.; Nelson, Leonard Y.; Berg, Joel H.; Seibel, Eric J.

    2013-01-01

    Abstract. There is currently a need for a safe and effective way to detect and diagnose early stages of childhood caries. A multimodal optical clinical prototype for diagnosing caries demineralization in vivo has been developed. The device can be used to quickly image and screen for any signs of demineralized enamel by obtaining high-resolution and high-contrast surface images using a 405-nm laser as the illumination source, as well as obtaining autofluorescence and bacterial fluorescence images. When a suspicious region of demineralization is located, the device also performs dual laser fluorescence spectroscopy using 405- and 532-nm laser excitation. An autofluorescence ratio of the two excitation lasers is computed and used to quantitatively diagnose enamel health. The device was tested on five patients in vivo as well as on 28 extracted teeth with clinically diagnosed carious lesions. The device was able to provide detailed images that highlighted the lesions identified by the clinicians. The autofluorescence spectroscopic ratios obtained from the extracted teeth successfully quantitatively discriminated between sound and demineralized enamel. PMID:23986369

  5. Ultracompact alignment-free single molecule fluorescence device with a foldable light path.

    PubMed

    Singh, Niraj Kumar; Chacko, Jenu V; Sreenivasan, Varun K A; Nag, Suman; Maiti, Sudipta

    2011-02-01

    Instruments with single-molecule level detection capabilities can potentially benefit a wide variety of fields, including medical diagnostics. However, the size, cost, and complexity of such devices have prevented their widespread use outside sophisticated research laboratories. Fiber-only devices have recently been suggested as smaller and simpler alternatives, but thus far, they have lacked the resolution and sensitivity of a full-fledged system, and accurate alignment remains a critical requirement. Here we show that through-space reciprocal optical coupling between a fiber and a microscope objective, combined with wavelength division multiplexing in optical fibers, allows a drastic reduction of the size and complexity of such an instrument while retaining its resolution. We demonstrate a 4 × 4 × 18 cm(3) sized fluorescence correlation spectrometer, which requires no alignment, can analyze kinetics at the single-molecule level, and has an optical resolution similar to that of much larger microscope based devices. The sensitivity can also be similar in principle, though in practice it is limited by the large background fluorescence of the commonly available optical fibers. We propose this as a portable and field deployable single molecule device with practical diagnostic applications. PMID:21361684

  6. [Temporal behavior of light emission of dielectric barrier discharges in air at atmospheric pressure].

    PubMed

    Yin, Zeng-qian; Dong, Li-fang; Han, Li; Li, Xue-chen; Chai, Zhi-fang

    2002-12-01

    The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges. PMID:12914154

  7. Monitoring of Plant Light/Dark Cycles Using Air-coupled Ultrasonic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fariñas, M. D.; Sancho-Knapik, D.; Peguero-Pina, J.; Gil-Pelegrín, E.; Álvarez-Arenas, T. E. G.

    This work presents the application of a technique based on the excitation, sensing and spectral analysis of leaves thickness resonances using air-coupled and wide-band ultrasound to monitor variations in leaves properties due to the plant response along light/dark cycles. The main features of these resonances are determined by the tautness of the cells walls in such a way that small modifications produced by variations in the transpiration rate, stomata aperture or water potential have a direct effect on the thickness resonances that can be measured in a completely non-invasive and contactless way. Results show that it is possible to monitor leaves changes due to variations in light intensity along the diurnal cycle, moreover, the technique reveals differences in the leaf response for different species and also within the same species but for specimens grown under different conditions that present different cell structures at the tissue level.

  8. Modification of energy-transfer processes in the cyanobacterium, Arthrospira platensis, to adapt to light conditions, probed by time-resolved fluorescence spectroscopy.

    PubMed

    Akimoto, Seiji; Yokono, Makio; Aikawa, Shimpei; Kondo, Akihiko

    2013-11-01

    In cyanobacteria, the interactions among pigment-protein complexes are modified in response to changes in light conditions. In the present study, we analyzed excitation energy transfer from the phycobilisome and photosystem II to photosystem I in the cyanobacterium Arthrospira (Spirulina) platensis. The cells were grown under lights with different spectral profiles and under different light intensities, and the energy-transfer characteristics were evaluated using steady-state absorption, steady-state fluorescence, and picosecond time-resolved fluorescence spectroscopy techniques. The fluorescence rise and decay curves were analyzed by global analysis to obtain fluorescence decay-associated spectra. The direct energy transfer from the phycobilisome to photosystem I and energy transfer from photosystem II to photosystem I were modified depending on the light quality, light quantity, and cultivation period. However, the total amount of energy transferred to photosystem I remained constant under the different growth conditions. We discuss the differences in energy-transfer processes under different cultivation and light conditions. PMID:23605291

  9. Improved light extraction of nitride-based flip-chip light-emitting diodes by forming air voids on Ar-implanted sapphire substrate

    NASA Astrophysics Data System (ADS)

    Yeh, Yu-Hsiang; Sheu, Jinn-Kong; Lee, Ming-Lun; Chen, Po-Cheng; Yang, Yu-Chen; Yen, Cheng-Hsiung; Lai, Wei-Chih

    2014-09-01

    GaN-based flip-chip light emitting diodes (FC-LEDs) with embedded air voids grown on a selective-area Arimplanted AlN/sapphire (AIAS) substrate was demonstrated in this study. The proposed FC LED with an embedded light scattering layer can destroy the light interference and thereby increase the LEE of GaN-based flip-chip LEDs. The epitaxial layers grown on Ar-implanted regions exhibited lower growth rates compared with those grown on implantation-free regions. Accordingly, air voids formed over the implanted regions after merging laterally grown GaN facet fronts. The light-output power of LEDs grown on AIAS was greater than that of LEDs grown on implantation free sapphire substrates. At an injection current of 700 mA, the output power of LEDs grown on AIAS was enhanced by 20% compared with those of LEDs without embedded air voids. The increase in output power was mainly attributed to the scattering of light around the air voids, which increased the probability of photons escaping from the LEDs. This study on FC LEDs with embedded light-scattering layer highlights the potential application of these LEDs as an alternative to conventional patterned sapphire substrates for improving the LEE of GaN/sapphire-based LEDs. Based on ray tracing simulation, if the height and the width of bottom of gaps were increased to 3 μm, the Lop could be enhanced over 60%.

  10. Limited-view light sheet fluorescence microscopy for three dimensional volume imaging

    NASA Astrophysics Data System (ADS)

    Rasmi, C. K.; Mohan, Kavya; Madhangi, M.; Rajan, K.; Nongthomba, U.; Mondal, Partha P.

    2015-12-01

    We propose and demonstrate a limited-view light sheet microscopy (LV-LSM) for three dimensional (3D) volume imaging. Realizing that longer and frequent image acquisition results in significant photobleaching, we have taken limited angular views (18 views) of the macroscopic specimen and integrated with maximum likelihood (ML) technique for reconstructing high quality 3D volume images. Existing variants of light-sheet microscopy require both rotation and translation with a total of approximately 10-fold more views to render a 3D volume image. Comparatively, LV-LSM technique reduces data acquisition time and consequently minimizes light-exposure by many-folds. Since ML is a post-processing technique and highly parallelizable, this does not cost precious imaging time. Results show noise-free and high contrast volume images when compared to the state-of-the-art selective plane illumination microscopy.

  11. THE IMPACT OF NONPHOTOCHEMICAL QUENCHING OF FLUORESCENCE ON THE PHOTON BALANCE IN DIATOMS UNDER DYNAMIC LIGHT CONDITIONS(1).

    PubMed

    Su, Wanwen; Jakob, Torsten; Wilhelm, Christian

    2012-04-01

    The nonphotochemical quenching (NPQ) of fluorescence is an important photoprotective mechanism in particular under dynamic light conditions. Its photoprotective potential was suggested to be a functional trait of algal diversity. In the present study, the influence of the photoprotective capacity on the growth balance was investigated in two diatoms, which possess different NPQ characteristics. It was hypothesized that under fluctuating light conditions Cyclotella meneghiniana Kütz. would benefit from its large and flexible NPQ potential, whereas the comparably small NPQ capacity in Skeletonema costatum (Grev.) Cleve should exert an unfavorable impact on growth. The results of the study clearly falsify this hypothesis. Although C. meneghiniana possesses a fast NPQ component, this diatom was not able to recover its full NPQ capacity under fluctuating light. On the other hand, the induction of NPQ at relatively low irradiance in S. costatum resulted in rather small differences in the fraction of energy dissipation by the NPQ mechanism in the comparison of both diatoms. Larger differences were found in the metabolic characteristics. Both diatoms differed in their biomass composition, with a higher content of lipids in C. meneghiniana but higher amounts of carbohydrates in S. costatum. Finally, the lower degree of reduction in the biomass compensated for the higher respiration rates in S. costatum and resulted in a higher quantum efficiency of biomass production. An indirect correlation between the photoprotective and the metabolic capacity is discussed. PMID:27009723

  12. The effects of UV emission from compact fluorescent light exposure on human dermal fibroblasts and keratinocytes in vitro.

    PubMed

    Mironava, Tatsiana; Hadjiargyrou, Michael; Simon, Marcia; Rafailovich, Miriam H

    2012-01-01

    Compact fluorescent light (CFL) bulbs can provide the same amount of lumens as incandescent light bulbs, using one quarter of the energy. Recently, CFL exposure was found to exacerbate existing skin conditions; however, the effects of CFL exposure on healthy skin tissue have not been thoroughly investigated. In this study, we studied the effects of exposure to CFL illumination on healthy human skin tissue cells (fibroblasts and keratinocytes). Cells exposed to CFLs exhibited a decrease in the proliferation rate, a significant increase in the production of reactive oxygen species, and a decrease in their ability to contract collagen. Measurements of UV emissions from these bulbs found significant levels of UVC and UVA (mercury [Hg] emission lines), which appeared to originate from cracks in the phosphor coatings, present in all bulbs studied. The response of the cells to the CFLs was consistent with damage from UV radiation, which was further enhanced when low dosages of TiO(2) nanoparticles (NPs), normally used for UV absorption, were added prior to exposure. No effect on cells, with or without TiO(2) NPs, was observed when they were exposed to incandescent light of the same intensity. PMID:22724459

  13. Monitoring human neutrophil granule secretion by flow cytometry: secretion and membrane potential changes assessed by light scatter and a fluorescent probe of membrane potential

    SciTech Connect

    Fletcher, M.P.; Seligmann, B.E.

    1985-04-01

    Purified human peripheral blood polymorphonuclear neutrophils (PMN) were incubated at 37 degrees C with the fluorescent membrane potential sensitive cyanine dye di-O-C(5)(3) and exposed to a number of stimulatory agents (N-formylmethionylleucylphenylalanine (FMLP), cytochalasin B (cyto B) + FMLP, phorbol myristate acetate (PMA). Flow cytometry was utilized to measure changes in forward light scatter (FS), orthogonal light scatter (90 degrees-SC), and fluorescence intensity of individual cells over time. A saturating (10(-6) M) dose of FMLP lead to a significant increase in the cells' FS without a change in 90 degrees-SC as well as a heterogeneous loss of di-O-C(5)(3) fluorescence. PMA (100 ng/ml) also caused an increase in FS but a uniform loss of dye fluorescence by all cells (apparent depolarization). Cyto B + FMLP produced an increase in FS, a marked loss of 90 degrees-SC, and a uniform loss of fluorescence. Secretion experiments under identical incubation conditions indicated a significantly positive relationship between loss of enzyme markers or cell granularity and orthogonal light scatter (r . 0.959, 0.998, and 0.989 for loss of 90 degrees-SC vs lysozyme, beta-glucuronidase, and granularity index, respectively). Flow cytometric light scatter measurements may yield important information on the extent of prior cell degranulation or activation.

  14. Effect of imaging geometry on evaluating natural white-spot lesions using quantitative light-induced fluorescence.

    PubMed

    Ando, Masatoshi; Eckert, George J; Stookey, George K; Zero, Domenick T

    2004-01-01

    The objective of this study was to determine the effect of imaging geometry on evaluating natural white-spot lesions with quantitative light-induced fluorescence (QLF). A total of 34 specimens were prepared from extracted human premolars and permanent molars with white spots on the interproximal surface. The specimens were each adjusted to a final thickness of 3.0 mm. Images were acquired with the QLF system perpendicular to the white spots and at 5 degrees intervals up to 30 degrees above and below the perpendicular. The specimens were rotated around the buccolingual axis of the tooth (pitch angle) and around the long axis of the tooth (roll angle). The averages of fluorescence loss (DeltaF, %) and lesion size (mm2) were determined with QLF. Another variable, DeltaQ, which was defined as the fluorescence loss integrated over the lesion size (% x mm2), was also calculated. DeltaF was smaller when lesions were viewed from the cervical direction (angles less than 90 degrees ), and became bigger when viewed from the coronal direction. Roll angle did not significantly affect DeltaF. Apparent lesion size diminished with deviations from 90 degrees in both directions for pitch and roll angles. DeltaQ was affected by pitch and roll angles with the largest value at 90 degrees and values decreasing in both directions from 90 degrees. In general, there were significant differences for angles larger than 20 degrees from the perpendicular for all three QLF variables. This study suggests that angle is an important factor to control when performing QLF studies; however, small changes (deviations within 20 degrees ) have a minimal effect on QLF variables. PMID:14684976

  15. Analysis of complex samples using a portable multi-wavelength light emitting diode (LED) fluorescence spectrometer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectroscopic analysis of chemically complex samples often requires an increase n the dimensionality of the measured response surface. This often involves the measurement of emitted light intensities as functions of both wavelengths of excitation and emission resulting in the generation of an excita...

  16. Enhanced visualization of the bile duct via parallel white light and indocyanine green fluorescence laparoscopic imaging

    NASA Astrophysics Data System (ADS)

    Demos, Stavros G.; Urayama, Shiro

    2014-03-01

    Despite best efforts, bile duct injury during laparoscopic cholecystectomy is a major potential complication. Precise detection method of extrahepatic bile duct during laparoscopic procedures would minimize the risk of injury. Towards this goal, we have developed a compact imaging instrumentation designed to enable simultaneous acquisition of conventional white color and NIR fluorescence endoscopic/laparoscopic imaging using ICG as contrast agent. The capabilities of this system, which offers optimized sensitivity and functionality, are demonstrated for the detection of the bile duct in an animal model. This design could also provide a low-cost real-time surgical navigation capability to enhance the efficacy of a variety of other image-guided minimally invasive procedures.

  17. Fluorescent optical position sensor

    DOEpatents

    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.

  18. A system for endoscopic mechanically scanned localized proton MR and light-induced fluorescence emission spectroscopies

    NASA Astrophysics Data System (ADS)

    Sonmez, Ahmet E.; Webb, Andrew G.; Spees, William M.; Ozcan, Alpay; Tsekos, Nikolaos V.

    2012-09-01

    Molecular and near-cellular modalities offer new opportunities in assessing living tissue in situ, and multimodality approaches, which offer complementary information, may lead to improved characterization of tissue pathophysiology benefiting diagnosis and focal therapy. However, many such modalities are limited by their low penetration through tissue, which has led to minimally invasive trans-cannula approaches to place the corresponding sensors locally at the area of interest. This work presents a system for performing localized fluorescence emission and proton magnetic resonance (MR) spectroscopies via endoscopic access. The in-house developed side-firing 1.9-mm wide dual-sensor integrates a three-fiber optical sensor for fluorescence emission optical spectroscopy and a 1-mm circular radiofrequency (RF) coil for localized MR proton spectroscopy. An MR-compatible manipulator was developed for carrying and mechanically translating the dual-sensor along a linear access channel. The hardware and software control of the system allows reconfigurable synchronization of the manipulator-assisted translation of the sensor, and MR and optical data collection. The manipulator serves as the mechanical link for the three modalities and MR images, MR spectra and optical spectra are inherently co-registered to the MR scanner coordinate system. These spectra were then used to generate spatio-spectral maps of the fluorophores and proton MR-signal sources in three-compartment phantoms with optically- and MR-visible, and distinguishable, materials. These data demonstrate a good spatial match between MR images, MR spectra and optical spectra along the scanned path. In addition to basic research, such a system may have clinical applications for assessing and characterizing cancer in situ, as well as guiding focal therapies.

  19. Highly sensitive analysis of flavonoids by zwitterionic microemulsion electrokinetic chromatography coupled with light-emitting diode-induced fluorescence detection.

    PubMed

    Cao, Wan; Hu, Shuai-Shuai; Li, Xing-Ying; Pang, Xiao-Qing; Cao, Jun; Ye, Li-Hong; Dai, Han-Bin; Liu, Xiao-Juan; Da, Jian-Hua; Chu, Chu

    2014-09-01

    A rapid zwitterionic microemulsion electrokinetic chromatography (ZI-MEEKC) approach coupled with light-emitting-diode-induced fluorescence (LED-IF, 480nm) detection was proposed for the analysis of flavonoids. In the optimization process, we systematically investigated the separation conditions, including the surfactants, cosurfactants, pH, buffers and fluorescence parameters. It was found that the baseline separation of the seven flavonoids was obtained in less than 5min with a running buffer consisting of 92.9% (v/v) 5mM sodium borate, 0.6% (w/v) ZI surfactant, 0.5% (w/v) ethyl acetate and 6.0% (w/v) 1-butanol. High sensitivity was obtained by the application of LED-IF detection. The limits of detection for seven flavonoids were in the range of 3.30×10(-8) to 2.15×10(-6)molL(-1) without derivatization. Ultimately, the detection method was successfully applied to the analysis of flavonoids in hawthorn plant and food products with satisfactory results. PMID:25047822

  20. A New Molecular Design Based on Thermally Activated Delayed Fluorescence for Highly Efficient Organic Light Emitting Diodes.

    PubMed

    Rajamalli, Pachaiyappan; Senthilkumar, Natarajan; Gandeepan, Parthasarathy; Huang, Pei-Yun; Huang, Min-Jie; Ren-Wu, Chen-Zheng; Yang, Chi-Yu; Chiu, Ming-Jui; Chu, Li-Kang; Lin, Hao-Wu; Cheng, Chien-Hong

    2016-01-20

    Two benzoylpyridine-carbazole based fluorescence materials DCBPy and DTCBPy, bearing two carbazolyl and 4-(t-butyl)carbazolyl groups, respectively, at the meta and ortho carbons of the benzoyl ring, were synthesized. These molecules show very small ΔEST of 0.03 and 0.04 eV and transient PL characteristics indicating that they are thermally activated delayed fluorescence (TADF) materials. In addition, they show extremely different photoluminescent quantum yields in solution and in the solid state: in cyclohexane the value are 14 and 36%, but in the thin films, the value increase to 88.0 and 91.4%, respectively. The OLEDs using DCBPy and DTCBPy as dopants emit blue and green light with EQEs of 24.0 and 27.2%, respectively, and with low efficiency roll-off at practical brightness level. The crystal structure of DTCBPy reveals a substantial interaction between the ortho donor (carbazolyl) and acceptor (4-pyridylcarbonyl) unit. This interaction between donor and acceptor substituents likely play a key role to achieve very small ΔEST with high photoluminescence quantum yield. PMID:26709617

  1. Highly Efficient Nondoped Organic Light Emitting Diodes Based on Thermally Activated Delayed Fluorescence Emitter with Quantum-Well Structure.

    PubMed

    Meng, Lingqiang; Wang, Hui; Wei, Xiaofang; Liu, Jianjun; Chen, Yongzhen; Kong, Xiangbin; Lv, Xiaopeng; Wang, Pengfei; Wang, Ying

    2016-08-17

    Highly efficiency nondoped thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs) with multiquantum wells structure were demonstrated. By using an emitting layer with seven quantum wells, the nondoped TADF OLEDs exhibit high efficiency with EQE of 22.6%, a current efficiency of 69 cd/A, and a power efficiency of 50 lm/W, which are higher than those of the conventional doped OLED and among the best of the TADF OLEDs. The high performance of the devices can be ascribed to effective confinement of the charges and excitons in the emission layer by the quantum well structure. The emission layer with multiquantum well structure is demonstrated to be cost effective for highly efficient nondoped TADF OLEDs and holds great potential for organic electronics. PMID:27452075

  2. Triplet exciton confinement for enhanced fluorescent organic light-emitting diodes using a co-host system

    NASA Astrophysics Data System (ADS)

    Yoo, Han Kyu; Lee, Ho Won; Lee, Song Eun; Kim, Young Kwan; Kim, Se Hyun; Yoon, Seung Soo; Park, Jaehoon

    2016-05-01

    In this work, the co-host system within an emitting layer (EML) consists of the host and triplet managing (TM) host materials. A set of EML structures was fabricated with various concentrations of the TM host (0, 10, 30, 50, and 70%). The TM host triplet energy level is lower than the energy levels of the host and the guest, which leads to a reduction in the triplet exciton density and the singlet-triplet annihilation of the guest. Blue fluorescent organic light-emitting diodes exhibit a maximum luminous efficiency (LE) and an external quantum efficiency (EQE) of 9.74 cd/A and 4.92%, respectively. In addition, the efficiency roll-off ratios of the LE and the EQE are 14.25 and 13.16%, respectively.

  3. Pyridyl Pyrrolide Boron Complexes: The Facile Generation of Thermally Activated Delayed Fluorescence and Preparation of Organic Light-Emitting Diodes.

    PubMed

    Shiu, Yi-Jiun; Cheng, Yung-Chen; Tsai, Wei-Lung; Wu, Chung-Chih; Chao, Chun-Tien; Lu, Chin-Wei; Chi, Yun; Chen, Yi-Ting; Liu, Shih-Hung; Chou, Pi-Tai

    2016-02-01

    The electron positive boron atom usually does not contribute to the frontier orbitals for several lower-lying electronic transitions, and thus is ideal to serve as a hub for the spiro linker of light-emitting molecules, such that the electron donor (HOMO) and acceptor (LUMO) moieties can be spatially separated with orthogonal orientation. On this basis, we prepared a series of novel boron complexes bearing electron deficient pyridyl pyrrolide and electron donating phenylcarbazolyl fragments or triphenylamine. The new boron complexes show strong solvent-polarity dependent charge-transfer emission accompanied by a small, non-negligible normal emission. The slim orbital overlap between HOMO and LUMO and hence the lack of electron correlation lead to a significant reduction of the energy gap between the lowest lying singlet and triplet excited states (ΔET-S ) and thereby the generation of thermally activated delay fluorescence (TADF). PMID:26822378

  4. Fluorometric flow-immunoassay for alkylphenol polyethoxylates on a microchip containing a fluorescence detector comprised of an organic light emitting diode and an organic photodiode.

    PubMed

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-03-01

    A compact fluorescence detector was constructed on a microchip from an organic light emitting diode (OLED) as the light source and an organic photodiode (OPD) as the photo-detector and was used in an immunoassay for alkylphenol polyethoxylates (APE). The OLED based on a terbium complex emitted a sharp light at the main wavelength of 546 nm with a full width at half maximum of 9 nm. The incident photo-to-current conversion efficiency (IPCE) of the OPD fabricated with Fullerene 70 (C70) and tris[4-(5-phenylthiopen-2-yl)phenyl]-amine (TPTPA) was approximately 44% for light at a wavelength of 586 nm. The performance of the fluorescence detector was evaluated for the determination of resorufin (λ(em)=586 nm) and the photocurrent of the OPD due to the fluorescence of resorufin was proportional to the concentration of resorufin in the range from 0 to 18 µM with a detection limit (S/N=3) of 0.6 µM. The fluorescence detector was successfully utilized in a competitive enzyme-linked immunosorbent assay for APE, where an anti-APE antibody was immobilized on the surface of the channel of the Polydimethylsiloxane (PDMS) microchip or on the surface of magnetic microbeads. After an immunoreaction with a sample solution of APE containing a horse radish peroxidase (HRP)-labeled APE, the fluorescence of resorufin generated just after introduction of a mixed solution of Amplex Red and H2O2 was measured using the fluorescence detector. The calibration curve for the photocurrent signals of the OPD due to the fluorescence of resorufin against the logarithmic concentration of APE was sigmoidal in shape. The detection limits defined as IC80 were ca. 1 ppb and ca. 2 ppb, respectively, for the methods using the anti-APE antibody immobilized on the surface of the microchannel and in the case where the antibody was immobilized on the surface of magnetic microbeads. PMID:25618638

  5. Light-induced dynamic changes of NADPH fluorescence in Synechocystis PCC 6803 and its ndhB-defective mutant M55.

    PubMed

    Mi, H; Klughammer, C; Schreiber, U

    2000-10-01

    Blue-green fluorescence emission of intact cells of Synechocystis PCC6803 and of its ndhB-defective mutant M55 was measured with a standard pulse-amplitude-modulation chlorophyll fluorometer equipped with a new type of emitter-detector unit featuring pulse-modulated UV-A measuring light and a photomultiplier detector. A special illumination program of repetitive saturating light pulses with intermittent dark periods (10 s light, 40 s dark) was applied to elicit dynamic fluorescence changes under conditions of quasi-stationary illumination. The observed effects of artificial electron acceptors and inhibitors on the responses of wild-type and mutant M55 cells lead to the conclusion that changes of NAD(P)H fluorescence are measured. In control samples, a rapid phase of light-driven NADP reduction is overlapped by a somewhat slower phase of NADPH oxidation which is suppressed by iodoacetic acid and, hence, appears to reflect NADPH oxidation by the Calvin cycle. Mercury chloride transforms the light-driven positive response into a negative one, suggesting that inhibition of NADP reduction at the acceptor side of PSI leads to reduction of molecular oxygen, with the hydrogen peroxide formed (via superoxide) causing rapid oxidation of NADPH. The new fluorescence approach opens the way for new insights into the complex interactions between photosynthetic and respiratory pathways in cyanobacteria. PMID:11148271

  6. Extensive Air Shower Characteristics as Functions of Shower Age

    NASA Astrophysics Data System (ADS)

    Giller, Maria; Stojek, Hubert; Wieczorek, Grzegorz

    We show that extensive air showers (EAS) are all very similar when described by shower age and Molière length unit. This allows to analyze fluorescence and Cherenkov light emitted by showers in a unified and simple way.

  7. Magnetic and fluorescent graphene for dual modal imaging and single light induced photothermal and photodynamic therapy of cancer cells.

    PubMed

    Gollavelli, Ganesh; Ling, Yong-Chien

    2014-05-01

    Developing a simple and cost-effective strategy to diagnose and treat cancer with single and minimal dosage through noninvasive strategies are highly challenging. To make the theranostic strategy effective, single light induced photothermal and photodynamic reagent with dual modal imaging capability is highly desired. Herein, a simple non-covalent approach was adopted to immobilize hydrophobic silicon napthalocyanine bis (trihexylsilyloxide) (SiNc4) photosensitizer onto water dispersible magnetic and fluorescent graphene (MFG) via π-π stacking to yield MFG-SiNc4 functioned as a theranostic nanocarrier. Taking the advantage of broad near infra-red absorption (600-1200 nm) by graphene, photosensitizer of any wavelength within this range will facilitate the single light induced phototherapy. Phosphorescence spectra, singlet oxygen sensor green (SOSG) experiments, and 1,3-diphenyl isobenzofuran quenching studies confirm the generation of singlet (1)O2 upon photoirradiation. Confocal microscopic images reveal successful internalization of MFG-SiNc4 in HeLa cells; whereas T2-weighted magnetic resonance images of MFG reveal a significant concentration dependent darkening effect. In vitro photodynamic/photothermal therapeutic studies on HeLa cells have demonstrated that the killing efficacy of MFG-SiNc4 using a single light source is ∼97.9%, presumably owing to the combined effects of generating reactive oxygen species, local heating, and induction of apoptosis. The developed MFG-SiNc4 may thus be utilized as a potential theranostic nanocarrier for dual modal imaging and phototherapy of cancer cells with single light source for time and cost effective treatments with a minimal therapy dose. PMID:24602568

  8. Aerosol Light Absorption and Scattering Assessments and the Impact of City Size on Air Pollution

    NASA Astrophysics Data System (ADS)

    Paredes-Miranda, Guadalupe

    The general problem of urban pollution and its relation to the city population is examined in this dissertation. A simple model suggests that pollutant concentrations should scale approximately with the square root of city population. This model and its experimental evaluation presented here serve as important guidelines for urban planning and attainment of air quality standards including the limits that air pollution places on city population. The model was evaluated using measurements of air pollution. Optical properties of aerosol pollutants such as light absorption and scattering plus chemical species mass concentrations were measured with a photoacoustic spectrometer, a reciprocal nephelometer, and an aerosol mass spectrometer in Mexico City in the context of the multinational project "Megacity Initiative: Local And Global Research Observations (MILAGRO)" in March 2006. Aerosol light absorption and scattering measurements were also obtained for Reno and Las Vegas, NV USA in December 2008-March 2009 and January-February 2003, respectively. In all three cities, the morning scattering peak occurs a few hours later than the absorption peak due to the formation of secondary photochemically produced aerosols. In particular, for Mexico City we determined the fraction of photochemically generated secondary aerosols to be about 75% of total aerosol mass concentration at its peak near midday. The simple 2-d box model suggests that commonly emitted primary air pollutant (e.g., black carbon) mass concentrations scale approximately as the square root of the urban population. This argument extends to the absorption coefficient, as it is approximately proportional to the black carbon mass concentration. Since urban secondary pollutants form through photochemical reactions involving primary precursors, in linear approximation their mass concentration also should scale with the square root of population. Therefore, the scattering coefficient, a proxy for particulate matter

  9. Numerical modelling and in vivo analysis of fluorescent and laser light backscattered from glial brain tumors

    NASA Astrophysics Data System (ADS)

    Savelieva, Tatiana A.; Kalyagina, Nina A.; Kholodtsova, Maria N.; Loschenov, Victor B.; Goryainov, Sergey A.; Potapov, Aleksander A.

    2012-03-01

    Brain glial tumors have peculiar features of the perifocal region extension, characterized by its indistinct area, which complicates determination of the borders for tissue resection. In the present study filter-reduced back-scattered laser light signals, compared to the data from mathematical modeling, were used for description of the brain white matter. The simulations of the scattered light distributions were performed in a Monte Carlo program using scattering and absorption parameters of the different grades of the brain glial tumors. The parameters were obtained by the Mie calculations for three main types of scatterers: myelinated axon fibers, cell nuclei and mitochondria. It was revealed that diffuse-reflected light, measured at the perifocal areas of the glial brain tumors, shows a significant difference relative to the signal, measured at the normal tissue, which signifies the possibility to provide diagnostically useful information on the tissue state, and to determine the borders of the tumor, thus to reduce the recurrence appearance. Differences in the values of ratios of diffuse reflectance from active growth parts of tumors and normal white matter can be useful for determination of the degree of tumor progress during the spectroscopic analysis.

  10. High performance of InGaN light-emitting diodes by air-gap/GaN distributed Bragg reflectors.

    PubMed

    Ryu, Jae Hyoung; Kim, Hee Yun; Kim, Hyun Kyu; Katharria, Yashpal Singh; Han, Nam; Kang, Ji Hye; Park, Young Jae; Han, Min; Ryu, Beo Deul; Ko, Kang Bok; Suh, Eun-Kyoung; Hong, Chang-Hee

    2012-04-23

    The effect of air-gap/GaN DBR structure, fabricated by selective lateral wet-etching, on InGaN light-emitting diodes (LEDs) is investigated. The air-gap/GaN DBR structures in LED acts as a light reflector, and thereby improve the light output power due to the redirection of light into escape cones on both front and back sides of the LED. At an injection current of 20 mA, the enhancement in the radiometric power as high as 1.91 times as compared to a conventional LED having no DBR structure and a far-field angle as low as 128.2° are realized with air-gap/GaN DBR structures. PMID:22535092

  11. Lighting Up the Force: Investigating Mechanisms of Mechanotransduction Using Fluorescent Tension Probes

    PubMed Central

    Jurchenko, Carol

    2015-01-01

    The ability of cells to sense the physical nature of their surroundings is critical to the survival of multicellular organisms. Cellular response to physical cues from adjacent cells and the extracellular matrix leads to a dynamic cycle in which cells respond by remodeling their local microenvironment, fine-tuning cell stiffness, polarity, and shape. Mechanical regulation is important in cellular development, normal morphogenesis, and wound healing. The mechanisms by which these finely balanced mechanotransduction events occur, however, are not well understood. In large part, this is due to the limited availability of tools to study molecular mechanotransduction events in live cells. Several classes of molecular tension probes have been recently developed which are rapidly transforming the study of mechanotransduction. Molecular tension probes are primarily based on fluorescence resonance energy transfer (FRET) and report on piconewton scale tension events in live cells. In this minireview, we describe the two main classes of tension probes, genetically encoded tension sensors and immobilized tension sensors, and discuss the advantages and limitations of each type. We discuss future opportunities to address major biological questions and outline the challenges facing the next generation of molecular tension probes. PMID:26031334

  12. Simultaneous Filtered and Unfiltered Light Scattering Measurements in Laser Generated Air Sparks

    NASA Astrophysics Data System (ADS)

    Limbach, Christopher; Miles, Richard

    2013-09-01

    Elastic laser light scattering may be used to measure the thermofluidic properties of gases and plasmas, including but not limited to density, temperature and velocity. Most of this information is contained within the spectra of the scattered radiation. This may be measured directly through dispersion or indirectly, by passing the light through an atomic or molecular vapor filter with known absorption features. In this work, filtered and unfiltered laser light scattering is used to diagnose air sparks generated by a 1064 nm Q-switched laser. The probe laser consists of a second Q-switched Nd:YAG laser frequency doubled to 532 nm. Simultaneous unfiltered and filtered images of the scattering are captured by a Princeton Instruments ICCD camera by using a 50 mm diameter concave re-imaging mirror. The filter consists of a well-characterized molecular Iodine cell. In the shock wave formed by the laser spark, spatially resolved measurements of density, temperature and radial velocity are extracted and compared with theory and models. Measurements in the spark core probe the ion feature of the electron Thomson scattering, from which ne and T can be extracted with the assumption Te =Ti . Partial funding was provided by General Electric Global Research Center: Niskayuna, New York. The first author is also supported by a National Defense Science and Engineering Graduate Fellowship.

  13. Fluorescent minerals - A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments

    NASA Astrophysics Data System (ADS)

    Omairi, Tareq; Wainwright, Milton

    2015-07-01

    We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark.

  14. Fluorescent minerals--A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments.

    PubMed

    Omairi, Tareq; Wainwright, Milton

    2015-07-01

    We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark. PMID:26256632

  15. Autoregressive-model-based fluorescence-lifetime measurements by phase-modulation fluorometry using a pulsed-excitation light source and a high-gain photomultiplier tube.

    PubMed

    Iwata, Tetsuo; Ito, Ritsuki; Mizutani, Yasuhiro; Araki, Tsutomu

    2009-11-01

    We propose a novel method for measuring fluorescence lifetimes by use of a pulsed-excitation light source and an ordinary or a high-gain photomultiplier tube (PMT) with a high-load resistor. In order to obtain the values of fluorescence lifetimes, we adopt a normal data-processing procedure used in phase-modulation fluorometry. We apply an autoregressive (AR)-model-based data-analysis technique to fluorescence- and reference-response time-series data obtained from the PMT in order to derive plural values of phase differences at a repetition frequency of the pulsed-excitation light source and its harmonic ones. The connection of the high-load resistor enhances sensitivity in signal detection in a certain condition. Introduction of the AR-model-based data-analysis technique improves precision in estimating the values of fluorescence lifetimes. Depending on the value of the load resistor and that of the repetition frequency, plural values of fluorescence lifetimes are obtained at one time by utilizing the phase information of harmonic frequencies. Because the proposed measurement system is simple to construct, it might be effective when we need to know approximate values of fluorescence lifetimes readily, such as in the field of biochemistry for a screening purpose. PMID:19891834

  16. Linearly polarized photons from Compton backscattering of laser light for nuclear resonance fluorescence experiments

    NASA Astrophysics Data System (ADS)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S.; Yamazaki, T.; Mikado, T.; Chiwaki, M.; Yamada, K.; Suzuki, R.; Sei, N.

    1994-12-01

    Elastically scattered photons from 208Pb(γ pol, γ) have been measured with completely polarized photons. The polarized photons (laser Compton photons) can be generated by Compton backscattering of laser light. The energy of the polarized LCPs ranges from 1 to 10 MeV by using a Q-switched Nd:YAG laser and the storage ring TERAS at Electrotechnical Laboratory. We can rotate the polarization axis of the LCPs by using the laser polarization controller to diminish the systematic error in the measurement system. Parities of J = 1 levels in 208Pb, Ex = 5.514 and 4.841 MeV, were clearly determined to be negative.

  17. Highly efficient exciplex organic light-emitting diodes using thermally activated delayed fluorescent emitters as donor and acceptor materials

    NASA Astrophysics Data System (ADS)

    Jeon, Sang Kyu; Yook, Kyoung Soo; Lee, Jun Yeob

    2016-06-01

    Highly efficient exciplex type organic light-emitting diodes were developed using thermally activated delayed fluorescent emitters as donors and acceptors of an exciplex. Blue emitting bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) was a donor and 9,9‧-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole) (DDCzTrz) and 9,9‧,9″-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(9H-carbazole) (TCzTrz) were acceptor materials. The exciplexes of DMAC-DPS:TCzTrz and DMAC-DPS:DDCzTrz resulted in high photoluminescence quantum yield and high quantum efficiency in the green exciplex organic light-emitting diodes. High quantum efficiencies of 13.4% and 15.3% were obtained in the DMAC-DPS:DDCzTrz and DMAC-DPS:TCzTrz exciplex devices.

  18. Highly efficient exciplex organic light-emitting diodes using thermally activated delayed fluorescent emitters as donor and acceptor materials.

    PubMed

    Jeon, Sang Kyu; Yook, Kyoung Soo; Lee, Jun Yeob

    2016-06-01

    Highly efficient exciplex type organic light-emitting diodes were developed using thermally activated delayed fluorescent emitters as donors and acceptors of an exciplex. Blue emitting bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) was a donor and 9,9'-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole) (DDCzTrz) and 9,9',9″-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(9H-carbazole) (TCzTrz) were acceptor materials. The exciplexes of DMAC-DPS:TCzTrz and DMAC-DPS:DDCzTrz resulted in high photoluminescence quantum yield and high quantum efficiency in the green exciplex organic light-emitting diodes. High quantum efficiencies of 13.4% and 15.3% were obtained in the DMAC-DPS:DDCzTrz and DMAC-DPS:TCzTrz exciplex devices. PMID:27098231

  19. Light up ClO(-) in live cells using an aza-coumarin based fluorescent probe with fast response and high sensitivity.

    PubMed

    Fan, Jiangli; Mu, Huiying; Zhu, Hao; Wang, Jingyun; Peng, Xiaojun

    2015-07-01

    Hypochlorous acid (HClO)/hypochlorite (ClO(-)), one of the reactive oxygen species (ROS), is a key microbicidal agent used for natural defense; however, HClO is also responsible for some human diseases. Although much effort has been made to develop HClO-selective fluorescent probes, many of them display a delayed response time and nanomole-sensitive probes are rare. In this study, we designed and synthesized an aza-coumarin based fluorescent probe AC-ClO for ClO(-) determination with fast response (completed within 2 min) and high sensitivity (detection limit is 25 nM). AC-ClO displayed a color change from pink to light yellow and a remarkable "turn-on" fluorescence response towards ClO(-). Confocal fluorescence microscopy experiments demonstrated that the probe could be applied for the live-cell imaging of exogenous and endogenous ClO(-). PMID:25997521

  20. Photosynthetic Light Utilization Efficiency, Photosystem II Heterogeneity, and Fluorescence Quenching in Chlamydomonas reinhardtii during the Induction of the CO2-Concentrating Mechanism 1

    PubMed Central

    Falk, Stefan; Palmqvist, Kristin

    1992-01-01

    The photosynthetic light-response curve, the relative amounts of the different photosystem II (PSII) units, and fluorescence quenching were altered in an adaptive manner when CO2-enriched wild-type Chlamydomonas reinhardtii cells were transferred to low levels of CO2. This treatment is known to result in the induction of an energy-dependent CO2-concentrating mechanism (CCM) that increases the internal inorganic carbon concentration and thus the photosynthetic CO2 utilization efficiency. After 3 to 6 h of low inorganic carbon treatment, several changes in the photosynthetic energy-transducing reactions appeared and proceeded for about 12 h. After this time, the fluorescence parameter variable/maximal fluorescence yield and the amounts of both PSIIα and PSIIβ (secondary quinone electron acceptor of PSII-reducing) centers had decreased, whereas the amount of PSIIβ (secondary quinone electron acceptor of PSII-nonreducing) centers had increased. The yield of noncyclic electron transport also decreased during the induction of the CCM, whereas both photochemical and nonphotochemical quenching of PSII fluorescence increased. Concurrent with these changes, the photosynthetic light-utilization efficiency also decreased significantly, largely attributed to a decline in the curvature parameter θ, the convexity of the photosynthetic light-response curve. Thus, it is concluded that the increased CO2 utilization efficiency in algal cells possessing the CCM is maintained at the cost of a reduced light utilization efficiency, most probably due to the reduced energy flow through PSII. PMID:16653047

  1. Localization of the human kinesin light chain gene (KNS2) to chromosome 14q32.3 by fluorescence in situ hybridization

    SciTech Connect

    Goedert, M.; Marsh, S.; Carter, N.

    1996-02-15

    This article reports on the localization of human kinesin light chain gene (KNS2) to human chromosome 14q32.3 using fluorescence in situ hybridization. Further studies will need to be conducted to see whether mutations in the KNS2 gene are associated with hereditary diseases. 10 refs., 1 fig.

  2. Dark-to-light transition in Synechococcus sp. PCC 7942 cells studied by fluorescence kinetics assesses plastoquinone redox poise in the dark and photosystem II fluorescence component and dynamics during state 2 to state 1 transition.

    PubMed

    Tsimilli-Michael, Merope; Stamatakis, Kostas; Papageorgiou, George C

    2009-03-01

    We investigated the dark-to-light transition in Synechococcus sp. PCC 7942 cells by a detailed analysis of fluorescence transients induced by strong red light. The transients, recorded with high data-acquisition, revealed all the steps of the fast (OJIP; 10(-5)-1 s) and slow phase (PSM(T); 1-10(3) s), kinetically distinguished with precision. Focusing on the OJIP-rise, we show, for the first time, how the variable to initial fluorescence ratio and the relative height of J-level can serve as indexes of the plastoquinone redox poise and the established state in the dark; hence, differences among cyanobacteria can be recognised in a simple way. Applying intermittent illumination (20-s light pulses separated by 10-s dark intervals) to induce dark-to-light transition and analysing the individual transients, we establish a method by which we determine the fluorescence component not originating from photosystem (PS) II and we assess PSII dynamics during state 2 to state 1 transition. The development of photochemical and non-photochemical quenching is also discussed, as well as evidences favouring the mobile antenna model. PMID:19205920

  3. Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

    NASA Astrophysics Data System (ADS)

    Conway, J.; Gogna, G. S.; Gaman, C.; Turner, M. M.; Daniels, S.

    2016-08-01

    Atomic oxygen number density [O] is measured in an air atmospheric pressure plasma jet (APPJ) using two-photon absorption laser induced fluorescence (TALIF). Gas flow is fixed at 8 slpm, the RF power coupled into the plasma jet varied between 5 W and 20 W, and the resulting changes in atomic oxygen density measured. Photolysis of molecular oxygen is employed to allow in situ calibration of the TALIF system. During calibration, O2 photo-dissociation and two-photon excitation of the resulting oxygen atoms are achieved within the same laser pulse. The atomic oxygen density produced by photolysis is time varying and spatially non-uniform which needs to be corrected for to calibrate the TALIF system for measurement of atomic oxygen density in plasma. Knowledge of the laser pulse intensity I 0(t), wavelength, and focal spot size allows correction factors to be determined using a rate equation model. Atomic oxygen is used for calibration and measurement, so the laser intensity can be increased outside the TALIF quadratic laser power dependence region without affecting the calibration reliability as the laser power dependence will still be the same for both. The atomic O density results obtained are not directly benchmarked against other known density measurement techniques. The results show that the plasma jet atomic oxygen content increases as the RF power coupled into the plasma increases.

  4. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Astrophysics Data System (ADS)

    Sundberg, Gale R.

    1990-05-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in gross take-off-weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  5. Civil air transport - A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1990-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology, with potential savings of over 10 percent in gross take off weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators, and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high-energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to future aircraft, both civil and military.

  6. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1990-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in gross take-off-weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  7. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1991-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in operating empty weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BIT) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  8. Bi-Directional Fluorescence Distribution and its Correction for Estimates of Gross Ecosystem Productivity and Photosynthetic Light-Use Efficiency

    NASA Astrophysics Data System (ADS)

    Liu, Liangyun; Liu, Xinjie

    2015-04-01

    Passive measurement of solar-induced chlorophyll fluorescence (SIF) presents a new way for directly estimating the photosynthetic activities. In this study, one diurnal multi-angular spectral experiment and three independent diurnal flux experiments were carried out on winter wheat and maize to assess directional emission of SIF for estimating photosynthesis activities. Firstly, the Bi-Directional Fluorescence Distribution Function (BFDF) of SIF was investigated. A BFDF shape similar to the red Bi-Directional Reflectance Distribution Function (BRDF) was observed for the directional SIF emissions at 688 nm. Secondly, the relationship between the directional emission of canopy SIF and BRDF reflectance was examined, finding a strict linear correlation between SIF and reflectance at 688 nm, with an R2> 0.80 for all seven BRDF observations on winter wheat. Then, a BFDF correction model for the canopy SIF at 688 nm was presented by dividing by the canopy reflectance, and about 65.3% of the directional variation was successfully removed. Finally, the BFDF-corrected SIF signals were linked to photosynthetic activities, including gross ecosystem productivity (GEP) and photosynthetic light-use efficiency (LUE), and the determination coefficients between photosynthetic activities and the BFDF-corrected SIF increased for most cases. For GEP, the determination coefficients were slightly improved from 0.563, 0.382, and 0.613 (for raw SIF signals) to 0.592, 0.473, and 0.640 for all three diurnal experiments. For LUE, the determination coefficients increased from 0.393, and 0.358 to 0.517, and 0.528 for two experiments, while deceased slightly from 0.695 to 0.607 for one experiment. Therefore, according to the above preliminary results, the canopy SIF cannot be regarded as isotropic, and the directional emission SIF may be an important uncertainty in estimates of GEP and LUE.

  9. Green light-emitting polyepinephrine-based fluorescent organic dots and its application in intracellular metal ions sensing.

    PubMed

    Gao, Zhong Feng; Li, Ting Ting; Xu, Xiao Lei; Liu, Yi Yao; Luo, Hong Qun; Li, Nian Bing

    2016-09-15

    In this paper, we present a class of bio-dots, polyepinephrine (PEP)-based fluorescent organic dots (PEP-FODs) for selective and sensitive detection of Fe(2+), Fe(3+), and Cu(2+). The PEP-FODs were derived from epinephrine via self-polymerization at relatively low temperature down to 60°C with low cytotoxicity and relative long lifetime (7.24ns). The surface morphology and optical properties of the synthesized PEP-FODs were characterized. We found that the diameters of PEP-FODs were mainly distributed in the narrow range of 2-4nm with an average diameter of 2.9nm. An optimal emission peak located at 490nm was observed when the green light-emitting PEP-FODs were excited at 400nm. It is discovered that Fe(2+), Fe(3+), and Cu(2+)can strongly quench the fluorescence of PEP-FODs through the nonradiative electron-transfer. The detection limit of 0.16, 0.67, and 0.15μM was obtained for Fe(2+), Fe(3+), and Cu(2+), respectively. The independent sensing platform of Fe(2+), Fe(3+), and Cu(2+)could be established by using NaF as a complexing agent and by regulating the reaction time between NaF and metal ions. Cell viability studies reveal that the as-prepared PEP-FODs possess good solubility and biocompatibility, making it as excellent imaging nanoprobes for intracellular Fe(2+), Fe(3+), and Cu(2+)sensing. The developed PEP-FODs might hold great promise to broaden applications in nanotechnology and bioanalysis. PMID:27108256

  10. Storage of LWR (light-water-reactor) spent fuel in air

    SciTech Connect

    Thomas, L.E.; Charlot, L.A.; Coleman, J.E. ); Knoll, R.W. )

    1989-12-01

    An experimental program is being conducted at Pacific Northwest Laboratory (PNL) to determine the oxidation response of light-water-reactor (LWR) spent fuels under conditions appropriate to fuel storage in air. The program is designed to investigate several independent variables that might affect the oxidation behavior of spent fuel. Included are temperature (135 to 230{degree}C), fuel burnup (to about 34 MWd/kgM), reactor type (pressurized and boiling water reactors), moisture level in the air, and the presence of a high gamma field. In continuing tests with declad spent fuel and nonirradiated UO{sub 2} specimens, oxidation rates were monitored by weight-gain measurements and the microstructures of subsamples taken during the weighing intervals were characterized by several analytical methods. The oxidation behavior indicated by weight gain and time to form powder will be reported in Volume III of this series. The characterization results obtained from x-ray diffractometry, transmission electron microscopy, scanning electron microscopy, and Auger electron spectrometry of oxidized fuel samples are presented in this report. 28 refs., 21 figs., 3 tabs.

  11. SuperNova, a monomeric photosensitizing fluorescent protein for chromophore-assisted light inactivation.

    PubMed

    Takemoto, Kiwamu; Matsuda, Tomoki; Sakai, Naoki; Fu, Donald; Noda, Masanori; Uchiyama, Susumu; Kotera, Ippei; Arai, Yoshiyuki; Horiuchi, Masataka; Fukui, Kiichi; Ayabe, Tokiyoshi; Inagaki, Fuyuhiko; Suzuki, Hiroshi; Nagai, Takeharu

    2013-01-01

    Chromophore-assisted light inactivation (CALI) is a powerful technique for acute perturbation of biomolecules in a spatio-temporally defined manner in living specimen with reactive oxygen species (ROS). Whereas a chemical photosensitizer including fluorescein must be added to specimens exogenously and cannot be restricted to particular cells or sub-cellular compartments, a genetically-encoded photosensitizer, KillerRed, can be controlled in its expression by tissue specific promoters or subcellular localization tags. Despite of this superiority, KillerRed hasn't yet become a versatile tool because its dimerization tendency prevents fusion with proteins of interest. Here, we report the development of monomeric variant of KillerRed (SuperNova) by direct evolution using random mutagenesis. In contrast to KillerRed, SuperNova in fusion with target proteins shows proper localization. Furthermore, unlike KillerRed, SuperNova expression alone doesn't perturb mitotic cell division. Supernova retains the ability to generate ROS, and hence promote CALI-based functional analysis of target proteins overcoming the major drawbacks of KillerRed. PMID:24043132

  12. Synthesis of fluorescent core-shell nanomaterials and strategies to generate white light

    SciTech Connect

    Singh, Amandeep; Kaur, Ramanjot; Pandey, O. P.; Wei, Xueyong; Sharma, Manoj E-mail: manojsharma@bilkent.edu.tr

    2015-07-28

    In this work, cadmium free core-shell ZnS:X/ZnS (X = Mn, Cu) nanoparticles have been synthesized and used for white light generation. First, the doping concentration of Manganese (Mn) was varied from 1% to 4% to optimize the dopant related emission and its optimal value was found to be 1%. Then, ZnS shell was grown over ZnS:Mn(1%) core to passivate the surface defects. Similarly, the optimal concentration of Copper (Cu) was found to be 0.8% in the range varied from 0.6% to 1.2%. In order to obtain an emission in the whole visible spectrum, dual doping of Mn and Cu was done in the core and the shell, respectively. A solid-solid mixing in different ratios of separately doped quantum dots (QDs) emitting in the blue green and the orange region was performed. Results show that the optimum mixture of QDs excited at 300 nm gives Commission Internationale del'Éclairage color coordinates of (0.35, 0.36), high color rendering index of 88, and correlated color temperature of 4704 K with minimum self-absorption.

  13. Inactivation of Escherichia coli on anatase and rutile nanoparticles using UV and fluorescent light

    SciTech Connect

    Caratto, V.; Aliakbarian, B.; Casazza, A.A.; Setti, L.; Bernini, C.; Perego, P.; Ferretti, M.

    2013-06-01

    Highlights: ► Photocatalytic deactivation of Escherichia coli in presence of TiO{sub 2} nanoparticles ► The presence of catalyst is less important when the radiation is in the UV range ► Rutile has an higher efficiency respect to anatase under visible light. - Abstract: The photocatalytic deactivation of Escherichia coli HB101 by two different structures of TiO{sub 2}, rutile and anatase (used separately and in a 1:1 mixture), was examined. The microorganism was deposited on a filter membrane containing 520 mg/m{sup 2} of TiO{sub 2} and then irradiated by a neon lamp. In order to study the rate of deactivation of the microorganism we studied four different exposure times: 20, 40, 60 and 90 min. The results showed that rutile has an antimicrobial activity higher than anatase, while the mixture had values near to the average between them in every condition. The highest difference in the inactivation capacity of the two structures is observable at shorter times. The effect of the different crystal phases was evaluated by Scanning Electron Microscopy.

  14. Does free-air carbon dioxide enrichment affect photochemical energy use by evergreen trees in different seasons? A chlorophyll fluorescence study of mature loblolly pine

    SciTech Connect

    Hymus, G.J.; Ellsworth, D.S.; Baker, N.R.; Long, S.P.

    1999-08-01

    Previous studies of the effects of growth at elevated CO{sup 2} on energy partitioning in the photosynthetic apparatus have produced conflicting results. The hypothesis was developed and tested that elevated CO{sub 2} increases photochemical energy use when there is a high demand for assimilates and decreases usage when demand is low. Modulated chlorophyll a fluorescence and leaf gas exchange were measured on needles at the tope of a mature, 12-m loblolly pine (Pinus taeda L.l) forest. Trees were exposed to ambient CO{sub 2} or ambient plus 20 Pa CO{sub 2} using free-air CO{sub 2} enrichment. During April and August, periods of shoot growth, light-saturated photo-synthesis and linear electron transport were increased by elevated CO{sub 2}. In November, when growth had ceased but temperatures were still moderate, CO{sub 2} treatment had no significant effect on linear electron transport. In February, when low temperatures were likely to inhibit translocation, CO{sub 2} treatment caused a significant decrease in linear electron transport. This coincided with a slower recovery of the maximum photosystem II efficiency on transfer of needles to the shade, indicating that growth in elevated CO{sub 2} induced a more persistent photoinhibition. Both the summer increase and the winter decrease in linear electron transport in elevated CO{sub 2} resulted from a change in photochemical quenching, not in the efficiency of energy transfer within the photosystem II antenna. There was no evidence of any effect of CO{sub 2} on photochemical energy sinks other than carbon metabolism. Their results suggest that elevated CO{sub 2} may increase the effects of winter stress on evergreen foliage.

  15. A method of observing cherenkov light from extensive air shower at Yakutsk EAS array

    NASA Astrophysics Data System (ADS)

    Timofeev, Lev; Anatoly, Ivanov

    2016-07-01

    Proposed a new method for measuring the cherenkov light from the extensive air shower (EAS) of cosmic rays (CR), which allows to determine not only the primary particle energy and angle of arrival, but also the parameters of the shower in the atmosphere - the maximum depth and "age". For measurements Cherenkov light produced by EAS is proposed to use a ground network of wide-angle telescopes which are separated from each other by a distance 100-300 m depending on the total number of telescopes operating in the coincidence signals, acting autonomously, or includes a detector of the charged components, radio waves, etc. as part of EAS. In a results such array could developed, energy measurement and CR angle of arrival data on the depth of the maximum and the associated mass of the primary particle generating by EAS. This is particularly important in the study of galactic cosmic ray in E> 10^14 eV, where currently there are no direct measurements of the maximum depth of the EAS.

  16. Electrophoretic deposition of fluorescent Cu and Au sheets for light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Liu, Jiale; Wu, Zhennan; Li, Tingting; Zhou, Ding; Zhang, Kai; Sheng, Yu; Cui, Jianli; Zhang, Hao; Yang, Bai

    2015-12-01

    Electrophoretic deposition (EPD) is a conventional method for fabricating film materials from nanometer-sized building blocks, and exhibits the advantages of low-cost, high-efficiency, wide-range thickness adjustment, and uniform deposition. Inspired by the interest in the application of two-dimensional (2D) nanomaterials, the EPD technique has been recently extended to building blocks with 2D features. However, the studies are mainly focused on simplex building blocks. The utilization of multiplex building blocks is rarely reported. In this work, we demonstrate a controlled EPD of Cu and Au sheets, which are 2D assemblies of luminescent Cu and Au nanoclusters. Systematic investigations reveal that both the deposition efficiency and the thickness are determined by the lateral size of the sheets. For Cu sheets with a large lateral size, a high ζ-potential and strong face-to-face van der Waals interactions facilitate the deposition with high efficiency. However, for Au sheets, the small lateral size and ζ-potential limit the formation of a thick film. To solve this problem, the deposition dynamics are controlled by increasing the concentration of the Au sheets and adding acetone. This understanding permits the fabrication of a binary EPD film by the stepwise deposition of Cu and Au sheets, thus producing a luminescent film with both Cu green emission and Au red emission. A white light-emitting diode prototype with color coordinates (x, y) = (0.31, 0.36) is fabricated by employing the EPD film as a color conversion layer on a 365 nm GaN clip and further tuning the amount of deposited Cu and Au sheets.Electrophoretic deposition (EPD) is a conventional method for fabricating film materials from nanometer-sized building blocks, and exhibits the advantages of low-cost, high-efficiency, wide-range thickness adjustment, and uniform deposition. Inspired by the interest in the application of two-dimensional (2D) nanomaterials, the EPD technique has been recently extended to

  17. Potential environmental impacts from the metals in incandescent, compact fluorescent lamp (CFL), and light-emitting diode (LED) bulbs.

    PubMed

    Lim, Seong-Rin; Kang, Daniel; Ogunseitan, Oladele A; Schoenung, Julie M

    2013-01-15

    Artificial lighting systems are transitioning from incandescent to compact fluorescent lamp (CFL) and light-emitting diode (LED) bulbs in response to the U.S. Energy Independence and Security Act and the EU Ecodesign Directive, which leads to energy savings and reduced greenhouse gas emissions. Although CFLs and LEDs are more energy-efficient than incandescent bulbs, they require more metal-containing components. There is uncertainty about the potential environmental impacts of these components and whether special provisions must be made for their disposal at the end of useful life. Therefore, the objective of this study is to analyze the resource depletion and toxicity potentials from the metals in incandescent, CFL, and LED bulbs to complement the development of sustainable energy policy. We assessed the potentials by examining whether the lighting products are to be categorized as hazardous waste under existing U.S. federal and California state regulations and by applying life cycle impact-based and hazard-based assessment methods (note that "life cycle impact-based method" does not mean a general life cycle assessment (LCA) but rather the elements in LCA used to quantify toxicity potentials). We discovered that both CFL and LED bulbs are categorized as hazardous, due to excessive levels of lead (Pb) leachability (132 and 44 mg/L, respectively; regulatory limit: 5) and the high contents of copper (111,000 and 31,600 mg/kg, respectively; limit: 2500), lead (3860 mg/kg for the CFL bulb; limit: 1000), and zinc (34,500 mg/kg for the CFL bulb; limit: 5000), while the incandescent bulb is not hazardous (note that the results for CFL bulbs excluded mercury vapor not captured during sample preparation). The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of

  18. Atmospheric Nitrogen Fluorescence Yield

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K. U.; Sokolsky, Pierre; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric nitrogen fluorescence. The nitrogen fluorescence yield from air shower electrons depends on the atmospheric composition. We will discuss the uncertainties in the fluorescence yield form electrons in the real atmosphere and describe a concept for a small balloon payload to measure the atmospheric fluorescence yield as a function of attitude.

  19. Prostate cancer detection using combined auto-fluorescence and light reflectance spectroscopy: ex vivo study of human prostates

    PubMed Central

    Sharma, Vikrant; Olweny, Ephrem O.; Kapur, Payal; Cadeddu, Jeffrey A.; Roehrborn, Claus G.; Liu, Hanli

    2014-01-01

    This study was conducted to evaluate the capability of detecting prostate cancer (PCa) using auto-fluorescence lifetime spectroscopy (AFLS) and light reflectance spectroscopy (LRS). AFLS used excitation at 447 nm with four emission wavelengths (532, 562, 632, and 684 nm), where their lifetimes and weights were analyzed using a double exponent model. LRS was measured between 500 and 840 nm and analyzed by a quantitative model to determine hemoglobin concentrations and light scattering. Both AFLS and LRS were taken on n = 724 distinct locations from both prostate capsular (nc = 185) and parenchymal (np = 539) tissues, including PCa tissue, benign peripheral zone tissue and benign prostatic hyperplasia (BPH), of fresh ex vivo radical prostatectomy specimens from 37 patients with high volume, intermediate-to-high-grade PCa (Gleason score, GS ≥7). AFLS and LRS parameters from parenchymal tissues were analyzed for statistical testing and classification. A feature selection algorithm based on multinomial logistic regression was implemented to identify critical parameters in order to classify high-grade PCa tissue. The regression model was in turn used to classify PCa tissue at the individual aggressive level of GS = 7,8,9. Receiver operating characteristic curves were generated and used to determine classification accuracy for each tissue type. We show that our dual-modal technique resulted in accuracies of 87.9%, 90.1%, and 85.1% for PCa classification at GS = 7, 8, 9 within parenchymal tissues, and up to 91.1%, 91.9%, and 94.3% if capsular tissues were included for detection. Possible biochemical and physiological mechanisms causing signal differences in AFLS and LRS between PCa and benign tissues were also discussed. PMID:24877012

  20. Heat transfer assembly for a fluorescent lamp and fixture

    DOEpatents

    Siminovitch, Michael J.; Rubenstein, Francis M.; Whitman, Richard E.

    1992-01-01

    In a lighting fixture including a lamp and a housing, a heat transfer structure is disclosed for reducing the minimum lamp wall temperature of a fluorescent light bulb. The heat transfer structure, constructed of thermally conductive material, extends from inside the housing to outside the housing, transferring heat energy generated from a fluorescent light bulb to outside the housing where the heat energy is dissipated to the ambient air outside the housing. Also disclosed is a method for reducing minimum lamp wall temperatures. Further disclosed is an improved lighting fixture including a lamp, a housing and the aforementioned heat transfer structure.

  1. Heat transfer assembly for a fluorescent lamp and fixture

    DOEpatents

    Siminovitch, M.J.; Rubenstein, F.M.; Whitman, R.E.

    1992-12-29

    In a lighting fixture including a lamp and a housing, a heat transfer structure is disclosed for reducing the minimum lamp wall temperature of a fluorescent light bulb. The heat transfer structure, constructed of thermally conductive material, extends from inside the housing to outside the housing, transferring heat energy generated from a fluorescent light bulb to outside the housing where the heat energy is dissipated to the ambient air outside the housing. Also disclosed is a method for reducing minimum lamp wall temperatures. Further disclosed is an improved lighting fixture including a lamp, a housing and the aforementioned heat transfer structure. 11 figs.

  2. Tracer-based laser-induced fluorescence measurement technique for quantitative fuel/air-ratio measurements in a hydrogen internal combustion engine.

    PubMed

    Blotevogel, Thomas; Hartmann, Matthias; Rottengruber, Hermann; Leipertz, Alfred

    2008-12-10

    A measurement technique for the quantitative investigation of mixture formation processes in hydrogen internal combustion engines (ICEs) has been developed using tracer-based laser-induced fluorescence (TLIF). This technique can be employed to fired and motored engine operation. The quantitative TLIF fuel/air-ratio results have been verified by means of linear Raman scattering measurements. Exemplary results of the simultaneous investigation of mixture formation and combustion obtained at an optical accessible hydrogen ICE are shown. PMID:19079454

  3. Cardiac Light-Sheet Fluorescent Microscopy for Multi-Scale and Rapid Imaging of Architecture and Function.

    PubMed

    Fei, Peng; Lee, Juhyun; Packard, René R Sevag; Sereti, Konstantina-Ioanna; Xu, Hao; Ma, Jianguo; Ding, Yichen; Kang, Hanul; Chen, Harrison; Sung, Kevin; Kulkarni, Rajan; Ardehali, Reza; Kuo, C-C Jay; Xu, Xiaolei; Ho, Chih-Ming; Hsiai, Tzung K

    2016-01-01

    Light Sheet Fluorescence Microscopy (LSFM) enables multi-dimensional and multi-scale imaging via illuminating specimens with a separate thin sheet of laser. It allows rapid plane illumination for reduced photo-damage and superior axial resolution and contrast. We hereby demonstrate cardiac LSFM (c-LSFM) imaging to assess the functional architecture of zebrafish embryos with a retrospective cardiac synchronization algorithm for four-dimensional reconstruction (3-D space + time). By combining our approach with tissue clearing techniques, we reveal the entire cardiac structures and hypertrabeculation of adult zebrafish hearts in response to doxorubicin treatment. By integrating the resolution enhancement technique with c-LSFM to increase the resolving power under a large field-of-view, we demonstrate the use of low power objective to resolve the entire architecture of large-scale neonatal mouse hearts, revealing the helical orientation of individual myocardial fibers. Therefore, our c-LSFM imaging approach provides multi-scale visualization of architecture and function to drive cardiovascular research with translational implication in congenital heart diseases. PMID:26935567

  4. Cardiac Light-Sheet Fluorescent Microscopy for Multi-Scale and Rapid Imaging of Architecture and Function

    NASA Astrophysics Data System (ADS)

    Fei, Peng; Lee, Juhyun; Packard, René R. Sevag; Sereti, Konstantina-Ioanna; Xu, Hao; Ma, Jianguo; Ding, Yichen; Kang, Hanul; Chen, Harrison; Sung, Kevin; Kulkarni, Rajan; Ardehali, Reza; Kuo, C.-C. Jay; Xu, Xiaolei; Ho, Chih-Ming; Hsiai, Tzung K.

    2016-03-01

    Light Sheet Fluorescence Microscopy (LSFM) enables multi-dimensional and multi-scale imaging via illuminating specimens with a separate thin sheet of laser. It allows rapid plane illumination for reduced photo-damage and superior axial resolution and contrast. We hereby demonstrate cardiac LSFM (c-LSFM) imaging to assess the functional architecture of zebrafish embryos with a retrospective cardiac synchronization algorithm for four-dimensional reconstruction (3-D space + time). By combining our approach with tissue clearing techniques, we reveal the entire cardiac structures and hypertrabeculation of adult zebrafish hearts in response to doxorubicin treatment. By integrating the resolution enhancement technique with c-LSFM to increase the resolving power under a large field-of-view, we demonstrate the use of low power objective to resolve the entire architecture of large-scale neonatal mouse hearts, revealing the helical orientation of individual myocardial fibers. Therefore, our c-LSFM imaging approach provides multi-scale visualization of architecture and function to drive cardiovascular research with translational implication in congenital heart diseases.

  5. Correlated light and electron microscopy observations of the uterine epithelial cell actin cytoskeleton using fluorescently labeled resin-embedded sections.

    PubMed

    Moore, Chad L; Cheng, Delfine; Shami, Gerald J; Murphy, Christopher R

    2016-05-01

    In order to perform correlative light and electron microscopy (CLEM) more precisely, we have modified existing specimen preparation protocols allowing fluorescence retention within embedded and sectioned tissue, facilitating direct observation across length scales. We detail a protocol which provides a precise correlation accuracy using accessible techniques in biological specimen preparation. By combining a pre-embedding uranyl acetate staining step with the progressive lowering of temperature (PLT) technique, a methacrylate embedded tissue specimen is ultrathin sectioned and mounted onto a TEM finder grid for immediate viewing in the confocal and electron microscope. In this study, the protocol is applied to rat uterine epithelial cells in vivo during early pregnancy. Correlative overlay data was used to track changes in filamentous actin that occurs in these cells from fertilization (Day 1) to implantation on Day 6 as part of the plasma membrane transformation, a process essential in the development of uterine receptivity in the rat. CLEM confirmed that the actin cytoskeleton is disrupted as apical microvilli are progressively lost toward implantation, and revealed the thick and continuous terminal web is replaced by a thinner and irregular actin band, with individually distinguishable filaments connecting actin meshworks which correspond with remaining plasma membrane protrusions. PMID:26930006

  6. Cardiac Light-Sheet Fluorescent Microscopy for Multi-Scale and Rapid Imaging of Architecture and Function

    PubMed Central

    Fei, Peng; Lee, Juhyun; Packard, René R. Sevag; Sereti, Konstantina-Ioanna; Xu, Hao; Ma, Jianguo; Ding, Yichen; Kang, Hanul; Chen, Harrison; Sung, Kevin; Kulkarni, Rajan; Ardehali, Reza; Kuo, C.-C. Jay; Xu, Xiaolei; Ho, Chih-Ming; Hsiai, Tzung K.

    2016-01-01

    Light Sheet Fluorescence Microscopy (LSFM) enables multi-dimensional and multi-scale imaging via illuminating specimens with a separate thin sheet of laser. It allows rapid plane illumination for reduced photo-damage and superior axial resolution and contrast. We hereby demonstrate cardiac LSFM (c-LSFM) imaging to assess the functional architecture of zebrafish embryos with a retrospective cardiac synchronization algorithm for four-dimensional reconstruction (3-D space + time). By combining our approach with tissue clearing techniques, we reveal the entire cardiac structures and hypertrabeculation of adult zebrafish hearts in response to doxorubicin treatment. By integrating the resolution enhancement technique with c-LSFM to increase the resolving power under a large field-of-view, we demonstrate the use of low power objective to resolve the entire architecture of large-scale neonatal mouse hearts, revealing the helical orientation of individual myocardial fibers. Therefore, our c-LSFM imaging approach provides multi-scale visualization of architecture and function to drive cardiovascular research with translational implication in congenital heart diseases. PMID:26935567

  7. Acoustic waves from mechanical impulses due to fluorescence resonant energy (Förster) transfer: Blowing a whistle with light

    NASA Astrophysics Data System (ADS)

    Zurita-Sánchez, J. R.; Henkel, C.

    2012-02-01

    We present a momentum transfer mechanism mediated by electromagnetic fields that originates in a system of two nearby molecules: one excited (donor D*) and the other in ground state (acceptor A). An intermolecular force related to fluorescence resonant energy or Förster transfer (FRET) arises in the unstable D*A molecular system, which differs from the equilibrium van der Waals interaction. Due to the its finite lifetime, a mechanical impulse is imparted to the relative motion in the system. We analyze the FRET impulse when the molecules are embedded in free space and find that its magnitude can be much greater than the single recoil photon momentum, getting comparable with the thermal momentum (Maxwell-Boltzmann distribution) at room temperature. In addition, we propose that this FRET impulse can be exploited in the generation of acoustic waves inside a film containing layers of donor and acceptor molecules, when a picosecond laser pulse excites the donors. This acoustic transient is distinguishable from that produced by thermal stress due to laser absorption, and may therefore play a role in photoacoustic spectroscopy. The effect can be seen as exciting a vibrating system like a string or organ pipe with light; it may be used as an opto-mechanical transducer.

  8. Use of invisible near infrared light fluorescence with indocyanine green and methylene blue in urology. Part 2

    PubMed Central

    Markuszewski, Marcin; Rho, Young Soo; Matuszewski, Marcin

    2014-01-01

    Introduction In the second part of this paper, concerning the use of invisible near infrared light (NIR) fluorescence with indocyanine green (ICG) and methylene blue (MB) in urology, other possible uses of this new technique will be presented. In kidney transplantation, this concerns allograft perfusion and real time NIR–guided angiography; moreover, perfusion angiography of tissue flaps, NIRF visualization of ureters, NIR–guided visualization of urinary calcifications, NIRF in male infertility and semen quality assessment. In this part, we have also analysed cancer targeting and imaging fluorophores as well as cost benefits associated with the use of these new techniques. Material and methods PubMed and Medline databases were searched for ICG and MB use in urological settings, along with data published in abstracts of urological conferences. Results Although NIR–guided ICG and MB are still in their initial phases, there have been significant developments in a few more major domains of urology, including 1) kidney transplantation: kidney allograft perfusion and vessel reconstruction; 2) angiography perfusion of tissue flaps; 3) visualization of ureters; 4) visualization of urinary calcifications; and 5) NIRF in male infertility and semen quality assessment. Conclusions Near infrared technology in urology is at its early stages. More studies are needed to assess the true potential and limitations of the technology. Initial studies show that this pioneering tool may influence various aspects of urology. PMID:25247093

  9. Highly Efficient Near-Infrared Delayed Fluorescence Organic Light Emitting Diodes Using a Phenanthrene-Based Charge-Transfer Compound.

    PubMed

    Wang, Shipan; Yan, Xianju; Cheng, Zong; Zhang, Hongyu; Liu, Yu; Wang, Yue

    2015-10-26

    Significant efforts have been made to develop high-efficiency organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) emitters with blue, green, yellow, and orange-red colors. However, efficient TADF materials with colors ranging from red, to deep-red, to near-infrared (NIR) have been rarely reported owing to the difficulty in molecular design. Herein, we report the first NIR TADF molecule TPA-DCPP (TPA=triphenylamine; DCPP=2,3-dicyanopyrazino phenanthrene) which has a small singlet-triplet splitting (ΔEST ) of 0.13 eV. Its nondoped OLED device exhibits a maximum external quantum efficiency (EQE) of 2.1 % with a Commission International de L'Éclairage (CIE) coordinate of (0.70, 0.29). Moreover, an extremely high EQE of nearly 10 % with an emission band at λ=668 nm has been achieved in the doped device, which is comparable to the most-efficient deep-red/NIR phosphorescent OLEDs with similar electroluminescent spectra. PMID:26480338

  10. Non-rigid contour-to-pixel registration of photographic and quantitative light-induced fluorescence imaging of decalcified teeth

    NASA Astrophysics Data System (ADS)

    Berkels, Benjamin; Deserno, Thomas; Ehrlich, Eva E.; Fritz, Ulrike B.; Sirazitdinova, Ekaterina; Tatano, Rosalia

    2016-03-01

    Quantitative light-induced fluorescence (QLF) is widely used to assess the damage of a tooth due to decalcification. In digital photographs, decalcification appears as white spot lesions, i.e. white spots on the tooth surface. We propose a novel multimodal registration approach for the matching of digital photographs and QLF images of decalcified teeth. The registration is based on the idea of contour-to-pixel matching. Here, the curve, which represents the shape of the tooth, is extracted from the QLF image using a contour segmentation by binarization and morphological processing. This curve is aligned to the photo with a non-rigid variational registration approach. Thus, the registration problem is formulated as minimization problem with an objective function that consists of a data term and a regularizer for the deformation. To construct the data term, the photo is pointwise classified into tooth and non-tooth regions. Then, the signed distance function of the tooth region allows to measure the mismatch between curve and photo. As regularizer a higher order, linear elastic prior is used. The resulting minimization problem is solved numerically using bilinear Finite Elements for the spatial discretization and the Gauss-Newton algorithm. The evaluation is based on 150 image pairs, where an average of 5 teeth have been captured from 32 subjects. All registrations have been confirmed correctly by a dental expert. The contour-to-pixel methods can directly be used in 3D for surface-to-voxel tasks.

  11. The role of cerebral spinal fluid in light propagation through the mouse head: improving fluorescence tomography with Monte Carlo modeling

    NASA Astrophysics Data System (ADS)

    Ancora, Daniele; Zacharopoulos, Athanasios; Ripoll, Jorge; Zacharakis, Giannis

    2016-03-01

    Optical Neuroimaging is a highly dynamical field of research owing to the combination of many advanced imaging techniques and computational tools that uncovered unexplored paths through the functioning of the brain. Light propagation modelling through such complicated structures has always played a crucial role as the basis for a high resolution and quantitative imaging where even the slightest improvement could lead to significant results. Fluorescence Diffuse Optical Tomography (fDOT), a widely used technique for three dimensional imaging of small animals and tissues, has been proved to be inaccurate for neuroimaging the mouse head without the knowledge of a-priori anatomical information of the subject. Commonly a normalized Born approximation model is used in fDOT reconstruction based on forward photon propagation using Diffusive Equation (DE) which has strong limitations in the optically clear regime. The presence of the Cerebral Spinal Fluid (CSF) instead, a thin optically clear layer surrounding the brain, can be more accurately taken into account using Monte Carlo approaches which nowadays is becoming more usable thanks to parallelized GPU algorithms. In this work we discuss the results of a synthetic experimental comparison, resulting to the increase of the accuracy for the Born approximation by introducing the CSF layer in a realistic mouse head structure with respect to the current model. We point out the importance of such clear layer for complex geometrical models, while for simple slab phantoms neglecting it does not introduce a significant error.

  12. 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

    SciTech Connect

    Not Available

    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.

  13. Analysis of the effects of blue light on morphofunctional status of in vitro cultured blastocysts from mice carrying gene of enhanced green fluorescent protein (EGFP).

    PubMed

    Sakharova, N Yu; Mezhevikina, L M; Smirnov, A A; Vikhlyantseva, E F

    2014-05-01

    We studied the effect of blue light (440-490 nm) on the development of late blastocysts of mice carrying the gene of enhanced green fluorescent protein (EGFP). Exposure to blue light for 20 min reduced adhesive properties of blastocysts and their capacity to form primary colonies consisting of the cells of inner cell mass, trophoblast, and extraembryonic endoderm. The negative effects of blue light manifested in morphological changes in the primary colonies and impairment of differentiation and migration of cells of the trophoblast and extraembryonic endoderm. The problems of cell-cell interaction and inductive influences of the inner cell mass on other cell subpopulations are discussed. EGFP blastocysts were proposed as the model for evaluation of the mechanisms underlying the effects of blue light as the major negative factor of visible light used in in vitro experiments on mammalian embryos. PMID:24913583

  14. The fluorescence detection of glutathione by ∙OH radicals' elimination with catalyst of MoS2/rGO under full spectrum visible light irradiation.

    PubMed

    Zhang, Nan; Ma, Weiguang; Han, Dongxue; Wang, Lingnan; Wu, Tongshun; Niu, Li

    2015-11-01

    In this study, a new method for the detection of glutathione (GSH) was designed based on the ∙OH radicals' elimination system due to the reducing ability of GSH for the first time. Fluorescence method with terephthalic acid (TA) as the probe was employed for the quantification of ∙OH radicals' production and elimination. Experimental conditions of ∙OH radicals' production were optimized in detail, and ∙OH radicals were found to be efficiently produced by the excellent catalysis performance of MoS2/rGO under full spectrum visible light irradiation. The introduction of GSH make fluorescent intensity decrease due to the elimination of ∙OH radicals. For the present fluorescence based GSH sensor, a wide detection range of 60.0-700.0 µM and excellent selectivity have been achieved. Furthermore, it has been successfully employed for the determination of GSH in commercial drug tablets and human serum. PMID:26452861

  15. Metal-free porphyrin-sensitized mesoporous titania films for visible-light indoor air oxidation.

    PubMed

    Ismail, Adel A; Bahnemann, Detlef W

    2010-09-24

    Transparent cubic mesoporous TiO2 films coated on soda-lime glass have been developed. A metal free meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) has been adsorbed on these TiO2 films from aqueous solutions. The results indicated that the obtained mesoporous TiO2 and 3D TPPS/TiO2 films are optically transparent and crack free (thickness ca. 200±20 nm). The introduction of the TPPS molecules has only a very small influence on the pore system and some limited pore blocking seems to occur. Transmission electron microscopy (TEM) images revealed that the adsorption of TPPS does not disrupt the meso order of TPPS/TiO2. The particle size of these TiO2 nanocrystals has been measured to be approximately 5-8 nm. TPPS/TiO2 photocatalysts, exhibiting regularly ordered mesopores, large surface area (ca. 102.5 cm(2) cm(-2)), and specific pore volume of about 0.1 mm(3) cm(-2), show improved light-harvesting efficiency as compared with other transparent TiO2 films. Employing the 3D TPPS/TiO2 photocatalyst, a quantum efficiency of 0.059 % has been obtained for the photodegradation of CH3CHO in the gas phase under visible-light illumination. Recycling tests demonstrated that the newly synthesized photocatalyst was quite stable during this gas-solid heterogeneous photocatalytic process because no significant decrease in photocatalytic activity was observed even after being used repetitively up to five times. Therefore, the newly synthesized transparent 3D TPPS/TiO2 photocatalysts can potentially be applied for low-cost air purification and self-cleaning applications. PMID:20806316

  16. Hazard analysis of long term viewing of visible laser light off of fluorescent diffuse reflective surfaces (post-it).

    SciTech Connect

    Augustoni, Arnold L.

    2006-10-01

    A laser hazard analysis is performed to evaluate if the use of fluorescent diffuse reflectors to view incident laser beams (Coherent Verdi 10W) present a hazard based on the ANSI Standard Z136.1-2000, American National Standard for the Safe Use of Lasers. The use of fluorescent diffuse reflectors in the alignment process does not pose an increased hazard because of the fluorescence at a different wavelength than that of the incident laser.

  17. Air-Hybrid Distributed Bragg Reflector Structure for Improving the Light Output Power in AlGalnP-Based LEDs.

    PubMed

    Oh, Hwa Sub; Ryu, Ho-Soung; Park, Sueng Ho; Jeong, Tak; Kim, Young Jin; Lee, Hyung Joo; Cho, Young Dae; Kwak, Joon-Seop; Baek, Jong Hyeob

    2015-07-01

    We investigated air gap-induced hybrid distributed Bragg reflectors (AH-DBRs) for use in high brightness and reliable AlGalnP-based light emitting diodes (LEDs). An air gap was inserted into the side of DBRs by selectively etching the Al(x),Ga1-xAs DBR structures. With the AH-DBR structures, the optical output power of LEDs was enhanced by 15% compared to LEDs having conventional DBRs, due to the effective reflection of obliquely incident light by the air gap structures. In addition, the electrical characteristics showed that the AH-DBR LED is a desirable structure for reducing the leakage current, as it suppresses unwanted surface recombinations. PMID:26373075

  18. The influence of negative ionization of the air on motor activity in Syrian hamsters ( Masocricetus auratus Waterhouse) in light conditions

    NASA Astrophysics Data System (ADS)

    Lenkiewicz, Zofia; Dabrowska, Barbara; Schiffer, Zofia

    1989-12-01

    The motor activity of Syrian hamsters ( Mesocricetus auratus Waterhouse) under the influence of negative ionization of the atmosphere applied for 10, 20 or 30 min per day was investigated. An ionizer with output of 14000 light negative ions per 1 cm3 of air was used. Studies carried out in the light phase of a 12∶12 h light/dark regime revealed a relation between the reaction of the animal and the time of day at which ionization was applied. Ionization for 20 or 30 min in the light phase decreased motor activity, while 10 min of ionization increased it compared to control animals. Ionization in the dark phase gave a more distinct rise in activity than that applied in the light phase for all three durations of ionization.

  19. Lighting.

    SciTech Connect

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  20. Transfer of ultraviolet photon energy into fluorescent light in the visible path represents a new and efficient protection mechanism of sunscreens.

    PubMed

    Vergou, Theognosia; Patzelt, Alexa; Richter, Heike; Schanzer, Sabine; Zastrow, Leonhard; Golz, Karin; Doucet, Olivier; Antoniou, Christina; Sterry, Wolfram; Lademann, Juergen

    2011-10-01

    The development of sunscreens with high sun protection factor (SPF) values but low filter concentrations is the ultimate goal. The purpose of the present study was to investigate why a sunscreen spray and cream with different concentrations of the same UV-filters provided the same SPF. Therefore, the homogeneity of the distribution of both sunscreens was investigated by laser scanning microscopy (LSM) and tape stripping (TS). Additionally, the energy transfer mechanisms of the sunscreens on the skin were analyzed. The TS and LSM showed a better homogeneity of the distribution of the spray. With Wood's light, a total absorption of the irradiation was detected in the spray area. In contrast, after cream treatment, an intensive fluorescent signal was observed. It was demonstrated that this fluorescent signal was caused by nonthermal energy transferred from the UV-filters to one compound of the cream releasing its excitation energy by fluorescence. This nonthermal energy transfer seemed to be the reason for the high efficiency of the cream, which is subjected to thermal relaxation. The transfer of UV photon energy into fluorescent light represents a new approach to increase the efficiency of sunscreens and could form the basis for a new generation of sunscreens. PMID:22029345

  1. Transfer of ultraviolet photon energy into fluorescent light in the visible path represents a new and efficient protection mechanism of sunscreens

    NASA Astrophysics Data System (ADS)

    Vergou, Theognosia; Patzelt, Alexa; Richter, Heike; Schanzer, Sabine; Zastrow, Leonhard; Golz, Karin; Doucet, Olivier; Antoniou, Christina; Sterry, Wolfram; Lademann, Juergen

    2011-10-01

    The development of sunscreens with high sun protection factor (SPF) values but low filter concentrations is the ultimate goal. The purpose of the present study was to investigate why a sunscreen spray and cream with different concentrations of the same UV-filters provided the same SPF. Therefore, the homogeneity of the distribution of both sunscreens was investigated by laser scanning microscopy (LSM) and tape stripping (TS). Additionally, the energy transfer mechanisms of the sunscreens on the skin were analyzed. The TS and LSM showed a better homogeneity of the distribution of the spray. With Wood's light, a total absorption of the irradiation was detected in the spray area. In contrast, after cream treatment, an intensive fluorescent signal was observed. It was demonstrated that this fluorescent signal was caused by nonthermal energy transferred from the UV-filters to one compound of the cream releasing its excitation energy by fluorescence. This nonthermal energy transfer seemed to be the reason for the high efficiency of the cream, which is subjected to thermal relaxation. The transfer of UV photon energy into fluorescent light represents a new approach to increase the efficiency of sunscreens and could form the basis for a new generation of sunscreens.

  2. Efficient polymer light-emitting diode with air-stable aluminum cathode

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Doumon, N. Y.; Blom, P. W. M.

    2016-03-01

    The fast degradation of polymer light-emitting diodes (PLEDs) in ambient conditions is primarily due to the oxidation of highly reactive metals, such as barium or calcium, which are used as cathode materials. Here, we report the fabrication of PLEDs using an air-stable partially oxidized aluminum (AlOx) cathode. Usually, the high work function of aluminum (4.2 eV) imposes a high barrier for injecting electrons into the lowest unoccupied molecular orbital (LUMO) of the emissive polymer (2.9 eV below the vacuum level). By partially oxidizing aluminum, its work function is decreased, but not sufficiently low for efficient electron injection. Efficient injection is obtained by inserting an electron transport layer of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT), which has its LUMO at 3.3 eV below vacuum, between the AlOx cathode and the emissive polymer. The intermediate F8BT layer not only serves as a hole-blocking layer but also provides an energetic staircase for electron injection from AlOx into the emissive layer. PLEDs with an AlOx cathode and F8BT interlayer exhibit a doubling of the efficiency as compared to conventional Ba/Al PLEDs, and still operate even after being kept in ambient atmosphere for one month without encapsulation.

  3. A dual-mode colorimetric and fluorometric "light on" sensor for thiocyanate based on fluorescent carbon dots and unmodified gold nanoparticles.

    PubMed

    Zhao, Dan; Chen, Chuanxia; Lu, Lixia; Yang, Fan; Yang, Xiurong

    2015-12-21

    A novel, highly sensitive and selective dual-readout (colorimetric and fluorometric) sensor based on fluorescent carbon dots (CDs) and unmodified gold nanoparticles (AuNPs) for the detection of thiocyanate (SCN(-)) was proposed. Amino-functionalized CDs could be readily adsorbed onto the surface of citrate-stabilized AuNPs through Au-N interactions, leading to the aggregation of AuNPs and the nonfluorescent off-state of CDs arising from potential fluorescence resonance energy transfer (FRET). However, SCN(-) had a stronger affinity toward AuNPs and could compete with CDs to bind onto the surface of AuNPs in priority, which prevented the aggregation of AuNPs and fluorescence quenching of CDs. Correspondingly, both the colorimetric and fluorometric signals remained "light-on". The color of the sensing solution remained red and the fluorescence remained unquenched. A distinguishable change in the color was observed at a SCN(-) concentration of 1 μM by the naked eye and a detection limit as low as 0.036 μM was obtained by virtue of fluorescence spectroscopy. Both colorimetric and fluorometric sensors exhibited excellent selectivity toward SCN(-) over other common metallic ions and anions. In addition, such a sensing assay featured simplicity, rapidity, cost-effectiveness and ease of operation without further modification. The accuracy and precision were evaluated based on the quantitative detection of SCN(-) in tap water and saliva samples with satisfactory results. PMID:26567774

  4. Cold-induced sudden reversible lowering of in vivo chlorophyll fluorescence after saturating light pulses : a sensitive marker for chilling susceptibility.

    PubMed

    Larcher, W; Neuner, G

    1989-03-01

    In chilling-sensitive plants (Glycine max, Saintpaulia ionantha, Saccharum officinarum) a sudden reversible drop in chlorophyll fluorescence occurs during photosynthetic induction immediately following saturating light pulses at low temperatures in the range 4 to 8 degrees C. A comparison of two soybean cultivars of different chilling sensitivities revealed that this phenomenon, termed lowwave, indicates specific thresholds of low temperature stress. Its occurrence under controlled chilling can be regarded as a quantitative marker for screening chilling susceptibility in angiosperms. PMID:16666615

  5. Remanagement of Singlet and Triplet Excitons in Single-Emissive-Layer Hybrid White Organic Light-Emitting Devices Using Thermally Activated Delayed Fluorescent Blue Exciplex.

    PubMed

    Liu, Xiao-Ke; Chen, Zhan; Qing, Jian; Zhang, Wen-Jun; Wu, Bo; Tam, Hoi Lam; Zhu, Furong; Zhang, Xiao-Hong; Lee, Chun-Sing

    2015-11-25

    A high-performance hybrid white organic light-emitting device (WOLED) is demonstrated based on an efficient novel thermally activated delayed fluorescence (TADF) blue exciplex system. This device shows a low turn-on voltage of 2.5 V and maximum forward-viewing external quantum efficiency of 25.5%, which opens a new avenue for achieving high-performance hybrid WOLEDs with simple structures. PMID:26436730

  6. Highly Efficient Orange and Red Phosphorescent Organic Light-Emitting Diodes with Low Roll-Off of Efficiency using a Novel Thermally Activated Delayed Fluorescence Material as Host.

    PubMed

    Wang, Hui; Meng, Lingqiang; Shen, Xingxing; Wei, Xiaofang; Zheng, Xiuli; Lv, Xiaopeng; Yi, Yuanping; Wang, Ying; Wang, Pengfei

    2015-07-15

    MTXSFCz with thermally activated delayed fluorescence is synthesized. Orange and red phosphorescent organic light-emitting diodes (PHOLEDs) with low efficiency roll-off exhibit external quantum efficiencies (EQE) up to 11.8% and 15.6%. The efficient upconversion from triplet to singlet of the host reduces the triplet density and thus affords a low efficiency roll-off of PHOLEDs. PMID:26033526

  7. Predicting caries by measuring its activity using quantitative light-induced fluorescence in vivo: a 2-year caries increment analysis.

    PubMed

    Meller, C; Santamaria, R M; Connert, T; Splieth, C

    2012-01-01

    The aim of this study was to analyse the predictive power of several clinical baseline parameters and the de-/remineralisation properties of in vivo etched sites measured with quantitative light-induced fluorescence (QLF) for subsequent 2-year caries increment. At baseline, in 44 children (8.23 ± 1.5 years) two areas (diameter 2 mm) of the buccal surface of a primary posterior tooth were etched with 36% phosphoric acid gel for 1 and 4 min, respectively. The etched sites were analysed immediately after etching (ΔQ1) and 24 h (ΔQ2) later by QLF. Additionally, caries status (deft/DMFT and initial caries), approximal plaque, bleeding on probing, and the patient's current use of fluorides were recorded. In the 2-year follow-up, 29 children were re-assessed. After clinical examination, the caries increment was calculated (ΔDMFT) and correlated with the baseline clinical variables and the QLF readings. Results showed a significant positive correlation between ΔQ(1 min) and the ΔDMFT (r = 0.44, p = 0.02). The ΔDMFT was significantly correlated with the baseline deft (r = 0.56, p = 0.002), cavitated active caries lesions (r = 0.52, p = 0.003), and filled teeth (r = 0.53, p = 0.003). In a regression analysis the use of fluoridated salt (SC = -0.10) and fluoride gel (SC = -0.14) were negatively associated with ΔDMFT. In conclusion, these findings suggest that the demineralisation properties of the etched sites and the outcome of the 24-hour measurements with QLF are significantly associated with caries increment. Previous caries experience strongly correlated with caries increment in this group of children. PMID:22614242

  8. Understanding growth kinetics of nanorods in microemulsion: a combined fluorescence correlation spectroscopy, dynamic light scattering, and electron microscopy study.

    PubMed

    Sharma, Soma; Pal, Nibedita; Chowdhury, Pramit K; Sen, Sobhan; Ganguli, Ashok K

    2012-12-01

    Even though nanostructures of various shapes and sizes can be controlled by microemulsions, there is substantial difficulty in understanding their growth mechanism. The evolution of nanostructures from the time of mixing of reactants to their final stage is a heterogeneous process involving a variety of intermediates. To obtain a deeper insight into these kinetic steps, we studied the slow growth kinetics (extending over eight days) of iron oxalate nanorods inside the polar core of water-in-oil microemulsion droplets made of cetyltrimethylammonium bromide/1-butanol/isooctane. Fluorescence correlation spectroscopy (FCS), dynamic light scattering (DLS), and transmission electron microscopy (TEM) have been employed to monitor the nanostructure growth at (near) the single-droplet level and in an ensemble. Analyzing FCS data with suitable kinetic model we obtain transient dimer lifetime (28 μs) and the droplet fusion rates (and fusion tendency) on each day as the reaction proceeds. The droplet fusion rate is found to directly control the nanorod growth in microemulsion solution and attains its maximum value (3.55 × 10(4) s(-1)) on day 6, when long nanorods are found in TEM data, implying that more and more reactants are fed into the growing system at this stage. Combining FCS, DLS, and TEM results, we find three distinct periods in the entire growth process: a long nucleation-dominant nanoparticle growth period which forms nanoparticles of critical (average) size of ∼53 nm, followed by a short period where isotropic nanoparticles switch to anisotropic growth to form nanorods, and finally elongation of nanorods and growth (and shrinking) of nanoparticles. PMID:23140268

  9. Radiative Processes In Air Excited By An ArF Laser

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.; Huo, Winifred; Laufer, Gabriel

    1990-01-01

    Report describes experimental and theoretical studies of emission spectrum of air excited by light from ArF laser. Purpose of studies to determine conditions under which fluorescence from O2 used to measure temperatures in aerodynamic flows.

  10. Effects of lighting and air movement on temperatures in reproductive organs of plants in a closed plant growth facility

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.

    Temperature increases in plant reproductive organs such as anthers and stigmas could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. There is a possibility such a situation could occur in Bioregenerative Life Support Systems under microgravity conditions in space because there will be little natural convective or thermal mixing. This study was conducted to determine the temperature of the plant reproductive organs as affected by illumination and air movement under normal gravitational forces on the earth and to make an estimation of the temperature increase in reproductive organs in closed plant growth facilities under microgravity in space. Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at air temperatures of 10 11 °C. Compared to the air temperature, temperatures of petals, stigmas and anthers of strawberry increased by 24, 22 and 14 °C, respectively, after 5 min of lighting at an irradiance of 160 W m-2 from incandescent lamps. Temperatures of reproductive organs and leaves of strawberry were significantly higher than those of rice. The temperatures of petals, stigmas, anthers and leaves of strawberry decreased by 13, 12, 13 and 14 °C, respectively, when the air velocity was increased from 0.1 to 1.0 ms-1. These results show that air movement is necessary to reduce the temperatures of plant reproductive organs in plant growth facilities.

  11. Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Wang, Shuai; Feng, Lungang; Xiong, Han; Su, Xilin; Yun, Feng

    2016-07-01

    Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ˜20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

  12. Summary report on effects at temperature, humidity, and fuel-air ratio on two air-cooled light aircraft engines

    NASA Technical Reports Server (NTRS)

    Kempke, E. E., Jr.

    1976-01-01

    Five different engine models were tested to experimentally characterize emissions and to determine the effects of variation in fuel-air ratio and spark timing on emissions levels and other operating characteristics such as cooling, misfiring, roughness, power acceleration, etc. The results are given of two NASA reports covering the Avco Lycoming 0-320-D engine testing and the recently obtained results on the Teledyne Continental TSIO-360-C engine.

  13. Ultrasensitive and universal fluorescent aptasensor for the detection of biomolecules (ATP, adenosine and thrombin) based on DNA/Ag nanoclusters fluorescence light-up system.

    PubMed

    Zhu, Ying; Hu, Xiao-Chun; Shi, Shuo; Gao, Ru-Ru; Huang, Hai-Liang; Zhu, Yan-Yan; Lv, Xiao-Yan; Yao, Tian-Ming

    2016-05-15

    We report here an ultrasensitive strategy based on the recognition-induced conformational alteration of aptamer and fluorescence turn-on abilities of guanine-rich (G-rich) DNA sequence in proximity to silver nanoclusters for adenosine triphosphate (ATP), adenosine (A) and thrombin (TB) detection. Herein, we designed two tailored DNA sequences noted as complementary DNA (abbreviated as c-DNA) and signal probe DNA (abbreviated as s-DNA), respectively. c-DNA is designed as a special structure consisting of a sequence complementary to aptamer at the 3'-end and a guanine-rich DNA sequence at the 5'-end; s-DNA contains a cytosine-rich sequence responsible for Ag NCs templated synthesis at the 3'-end and a link sequence (part of aptamer) complementary to partial of the c-DNA at the 5'-end. In the presence of target, the aptamer associated with the target, resulting in the formation of duplex DNA (dsDNA), the DNA-Ag NCs thereafter could close to the guanine-rich sequence, leading to enhanced fluorescence signal readout. The widespread application of the sensing system is achieved success in the detection of three biomolecules. ATP, adenosine and thrombin in the range of 0.5-8.0 μM, 0.5-7.0 μM and 50-900 nM could be linearly detected with the detection limits of 91.6 nM, 103.4 nM and 8.4 nM, respectively. This label-free and turn-on fluorescent sensing system employing the mechanism proposed here turns out to be sensitive, selective, and convenient for the detection of biomolecules without washing and separation steps. PMID:26706942

  14. Investigating the Cherenkov light lateral distribution function for primary proton and iron nuclei in extensive air showers

    NASA Astrophysics Data System (ADS)

    Al-Rubaiee, A. A.; Hashim, U.; Al-Douri, Y.

    2015-11-01

    The lateral distribution function (LDF) of Cherenkov radiation in extensive air showers (EAS) was simulated by CORSIKA program for the conditions of Yakutsk Cherenkov array at the high energy range (1013-1016) eV for two primary particles (p and Fe) for different zenith angles. By depending on Breit-Wigner function for analyzing of Cherenkov light LDF, a parameterization of Cherenkov light LDF was reconstructed by depending on CORSIKA simulation as a function of primary energy. The comparison between the estimated Cherenkov light LDF with the LDF that measured on the Yakutsk EAS array gives the ability of particle identification that initiated the shower and determination of particle's energy around the knee region. The extrapolation of approximated Cherenkov light LDF for energies 20 and 30 PeV was obtained for primary particles (p and Fe).

  15. EFFECT OF LASER LIGHT ON LASER PLASMAS: Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskiĭ, Yu M.; Moiseev, V. N.; Rovinskiĭ, R. E.; Tsenina, I. S.

    1993-01-01

    The dynamic and optical characteristics of the laser plasma produced during the application of a CO2 laser pulse to a target have been studied as a function of the ambient air pressure. The changes in the surface roughness of the sample after bombardment were studied as a function of the air pressure. It is concluded from the results that a transition from an air plasma to an erosion plasma occurs at a residual air pressure on the order of 1 torr. The experiment data support the existing picture of the process by which a plasma is produced near the surface of a target in air by laser pulses.

  16. Visualization of an adsorption model for surfactant transport from micelle solutions to a clean air/water interface using fluorescence microscopy.

    PubMed

    Song, Qing; Yuan, Mingjun

    2011-05-01

    This work pertains to visualizing a transport model for adsorption of surfactants from micelle solutions onto a clean air/water interface. Under the condition of surfactant adsorption from very dilute solutions, the time scale for diffusion of a surfactant monomer is much slower than the time scale for kinetic breakdown of the aggregates. A theoretical model predicts two regimes for the adsorption dynamics. We visualize these two regimes under the mechanism of solubilization using fluorescence microscopy, in which an insoluble fluorescent probe, NBD-HAD (4-(hexadecylamino)-7-nitrobenz-2-oxa-1,3-diazole), is used to illuminate the micelles. The dye fluoresces in the microenvironment of micelles but is quenched in the aqueous solution on laser excitation. The region containing micelles is illuminated, but the region which does not contain micelles appears dark. For surfactant solution of C(14)E(6) at concentration just above the critical micelle concentration (C(CMC)), C(CMC)=4.4 mg/L, a dark region between the bright image of the air/water interface and the micelle-containing zone is observed. This dark region becomes smaller with time and finally disappears once equilibrium is reached. For a surfactant solution of C(14)E(6) at the concentration of 4.74C(CMC), which is higher than a critical total surfactant concentration (C(T)(c)) of 4.25C(CMC), we observe bright images through surfactant solutions during the adsorption process. Fluorescence images validate the theoretical model. PMID:21349535

  17. Fluorescent protein-mediated colour polymorphism in reef corals: multicopy genes extend the adaptation/acclimatization potential to variable light environments.

    PubMed

    Gittins, John R; D'Angelo, Cecilia; Oswald, Franz; Edwards, Richard J; Wiedenmann, Jörg

    2015-01-01

    The genomic framework that enables corals to adjust to unfavourable conditions is crucial for coral reef survival in a rapidly changing climate. We have explored the striking intraspecific variability in the expression of coral pigments from the green fluorescent protein (GFP) family to elucidate the genomic basis for the plasticity of stress responses among reef corals. We show that multicopy genes can greatly increase the dynamic range over which corals can modulate transcript levels in response to the light environment. Using the red fluorescent protein amilFP597 in the coral Acropora millepora as a model, we demonstrate that its expression increases with light intensity, but both the minimal and maximal gene transcript levels vary markedly among colour morphs. The pigment concentration in the tissue of different morphs is strongly correlated with the number of gene copies with a particular promoter type. These findings indicate that colour polymorphism in reef corals can be caused by the environmentally regulated expression of multicopy genes. High-level expression of amilFP597 is correlated with reduced photodamage of zooxanthellae under acute light stress, supporting a photoprotective function of this pigment. The cluster of light-regulated pigment genes can enable corals to invest either in expensive high-level pigmentation, offering benefits under light stress, or to rely on low tissue pigment concentrations and use the conserved resources for other purposes, which is preferable in less light-exposed environments. The genomic framework described here allows corals to pursue different strategies to succeed in habitats with highly variable light stress levels. In summary, our results suggest that the intraspecific plasticity of reef corals' stress responses is larger than previously thought. PMID:25496144

  18. Fluorescent blue lights, injecting drug use and related health risk in public conveniences: findings from a qualitative study of micro-injecting environments.

    PubMed

    Parkin, Stephen; Coomber, Ross

    2010-07-01

    This paper presents findings relating to injecting drug users' experiences and opinions of public toilets illuminated with fluorescent blue lights and presents an empirical assessment of the intended deterrent effect of such installations. Data analysis identified that blue lights deterred less than half the sample interviewed. Furthermore over half (18/31) of the sample were prepared to inject in conditions specifically designed to deter injecting practice. Of these, 11 respondents were completely undeterred and 7 individuals were only partially deterred by blue light environments. These findings are discussed within the interpretative frameworks of Pierre Bourdieu's theory of habitus and symbolic violence. The authors conclude that fluorescent blue lights contribute towards the development of situated resistance by injecting drug users within a public injecting habitus; a resistance that produces and reproduces drug-related harm and is a behaviour that opposes the symbolic violence of harm reduction intervention. The paper concludes with suggestions for theory-driven practical intervention that may seek to disrupt the harmful elements of the public injecting habitus. PMID:20167527

  19. Abundance and Night Hourly Dispersal of the Vesicating Beetles of the Genus Paederus (Coleoptera: Staphylinidae) Attracted to Fluorescent, Incandescent, and Black Light Sources in the Brazilian Savanna.

    PubMed

    Lima, D C B; Costa, A A V; Silva, F S

    2015-01-01

    Paederus beetles are cosmopolitan medically important insects that cause dermatitis linearis to humans. In Brazil, despite the medical importance of these beetles, no studies focusing directly on the abundance and ecological features of harmful species exist. Therefore, this study aims at determining the abundance and the nocturnal hourly dispersal of Paederus species attracted to fluorescent, incandescent, and black light sources in the Brazilian savanna. Paederus species were captured from May to September for three consecutive years, between 2011 and 2013. The specimens were caught hourly, from 1800 to 0600 hours. Paederus beetles were attracted to incandescent, fluorescent, and black light lamps as light sources. A total of 959 individuals of five species were collected. The collected species were Paederus protensus Sharp (59.85%), Paederus columbinus Laporte de Castelnau (29.20%), Paederus mutans Sharp (7.09%), Paederus brasiliensis Erichson (3.34%), and Paederus ferus Erichson (0.52%). The black light was the most attractive source, and the darkest collecting point was the most representative for the number of individuals. The lowest catches were captured at full moon, and the highest catches were between 2200 and 0100 hours. Future investigations are needed to better understand the role of night temperature and soil humidity affecting the seasonal growth of Paederus beetle populations of northeastern Brazil. PMID:26336279

  20. ICPBC and C12-ICPBC: two new red emitting, fluorescent Ca2+ indicators excited with visible light.

    PubMed

    Roussakis, Emmanuel; Liepouri, Fotini; Nifli, Artemissia-Phoebe; Castanas, Elias; Deligeorgiev, Todor G; Katerinopoulos, Haralambos E

    2006-01-01

    Two new, visible-excited and red-emitting fluorescent Ca(2+) indicators were synthesized and the spectral profiles of their free and Ca(2+) bound forms were studied. The fluorescent properties of these probes are due to the extended conjugation of the chromeno[3',2':3,4]pyrido[1,2a][1,3]benzimidazole chromophore incorporated in their BAPTA-type, Ca(2+) chelating structure. The compounds, namely ICPBC and its N-dodecyl analog C12-ICPBC exhibit Ca(2+) dissociation constants of 7.7 and 18.0 microM, respectively. The fluorescence spectra of the probes showed a clear shift in excitation wavelength maxima upon Ca(2+) binding along with a large Stokes shift and changes in fluorescence intensity, indicating their potential use as Ca(2+) indicators. The ability of ICPBC to trace high calcium spikes was tested in the human HepG2 cell line with positive results. PMID:16236357

  1. Stomatal Opening in Isolated Epidermal Strips of Vicia faba. I. Response to Light and to CO2-free Air 1

    PubMed Central

    Fischer, R. A.

    1968-01-01

    This paper reports a consistent and large opening response to light + CO2-free air in living stomata of isolated epidermal strips of Vicia faba. The response was compared to that of non-isolated stomata in leaf discs floating on water; stomatal apertures, guard cell solute potentials and starch contents were similar in the 2 situations. To obtain such stomatal behavior, it was necessary to float epidermal strips on dilute KCl solutions. This suggests that solute uptake is necessary for stomatal opening. The demonstration of normal stomatal behavior in isolated epidermal strips provides a very useful system in which to investigate the mechanism of stomatal opening. It was possible to show independent responses in stomatal aperture to light and to CO2-free air. PMID:16656995

  2. Comparison of solar-induced chlorophyll fluorescence, light-use efficiency, and process-based GPP models in maize.

    PubMed

    Wagle, Pradeep; Zhang, Yongguang; Jin, Cui; Xiao, Xiangming

    2016-06-01

    Accurately quantifying cropland gross primary production (GPP) is of great importance to monitor cropland status and carbon budgets. Satellite-based light-use efficiency (LUE) models and process-based terrestrial biosphere models (TBMs) have been widely used to quantify cropland GPP at different scales in past decades. However, model estimates of GPP are still subject to large uncertainties, especially for croplands. More recently, space-borne solar-induced chlorophyll fluorescence (SIF) has shown the ability to monitor photosynthesis from space, providing new insights into actual photosynthesis monitoring. In this study, we examined the potential of SIF data to describe maize phenology and evaluated three GPP modeling approaches (space-borne SIF retrievals, a LUE-based vegetation photosynthesis model [VPM], and a process-based soil canopy observation of photochemistry and energy flux [SCOPE] model constrained by SIF) at a maize (Zea mays L.) site in Mead, Nebraska, USA. The result shows that SIF captured the seasonal variations (particularly during the early and late growing season) of tower-derived GPP (GPP_EC) much better than did satellite-based vegetation indices (enhanced vegetation index [EVI] and land surface water index [LSWI]). Consequently, SIF was strongly correlated with GPP_EC than were EVI and LSWI. Evaluation of GPP estimates against GPP_EC during the growing season demonstrated that all three modeling approaches provided reasonable estimates of maize GPP, with Pearson's correlation coefficients (r) of 0.97, 0.94, and 0.93 for the SCOPE, VPM, and SIF models, respectively. The SCOPE model provided the best simulation of maize GPP when SIF observations were incorporated through optimizing the key parameter of maximum carboxylation capacity (Vcmax). Our results illustrate the potential of SIF data to offer an additional way to investigate the seasonality of photosynthetic activity, to constrain process-based models for improving GPP estimates, and to

  3. Shedding new light on historical metal samples using micro-focused synchrotron X-ray fluorescence and spectroscopy

    NASA Astrophysics Data System (ADS)

    Grolimund, D.; Senn, M.; Trottmann, M.; Janousch, M.; Bonhoure, I.; Scheidegger, A. M.; Marcus, M.

    2004-10-01

    Synchrotron-based micro-X-ray fluorescence (micro-XRF) and micro-X-ray absorption spectroscopy (micro-XAS) were used in the present study to obtain spatially resolved micro-scale information on elemental composition, trace element distribution, chemical speciation and oxidation state and/or mineral phase distribution within historical iron artefacts dating from the Iron Age to early Medieval Times. Large area two-dimensional trace element distribution maps and oxidation state maps with micrometer spatial resolution were required to answer open archaeological questions in the context of ancient metal processing. The first set of examples was focusing on historical weapons and included two ancient iron sword blades. The micro-XRF maps revealed a distinct, highly correlated distribution pattern of trace elements such as As, Ni, Cu and Zn. Accordingly, the number of used raw materials could be determined unambiguously and key information concerning the used ancient smithing technique were gained. Further, the ability to record—in a fast manner—large area maps with high spatial resolution ('elemental screening') led to the discovery of a hitherto unknown enhanced occurrence of selected trace elements (Cu, Zn, and Au) at the blade surface. Complementary investigations by high resolution scanning electron microscopy were able to localize these trace metals within a carbon-rich matrix may be pointing towards an artifact induced during preservation. A second set of investigated artefacts is dealing with smithing waste products and related historical processing techniques and conditions. Synchrotron-based micro-XRF and micro-XAS were used to determine the structural composition as well as the spatial variation of the predominant Fe oxidation state and corresponding crystallographic phases. The study revealed the presence of distinct domains of Fe 0, Fe IIO (wustite), and α-Fe IIIOOH (goethite), separated by sharp domain boundaries. These findings help to gain new

  4. Food-Growing, Air- And Water-Cleaning Module

    NASA Technical Reports Server (NTRS)

    Sauer, R. L.; Scheld, H. W.; Mafnuson, J. W.

    1988-01-01

    Apparatus produces fresh vegetables and removes pollutants from air. Hydroponic apparatus performs dual function of growing fresh vegetables and purifying air and water. Leafy vegetables rooted in granular growth medium grow in light of fluorescent lamps. Air flowing over leaves supplies carbon dioxide and receives fresh oxygen from them. Adaptable to production of food and cleaning of air and water in closed environments as in underwater research stations and submarines.

  5. Image-Guided Sentinel Lymph Node Mapping and Nanotechnology-Based Nodal Treatment in Lung Cancer using Invisible Near-Infrared Fluorescent Light

    PubMed Central

    Khullar, Onkar; Frangioni, John V.; Colson, Yolonda L.

    2011-01-01

    Current methods for sentinel lymph node (SLN) mapping and nodal treatment in lung cancer remain inadequate for routine clinical use. Here we discuss the potential for using the combination of invisible near-infrared (NIR) fluorescent light and nanotechnology for these applications. NIR fluorescence imaging has recently received significant attention for in vivo imaging applications because of its low tissue autofluorescence, high photon penetration into living tissue, and high signal-to-background ratio. Our large animal in vivo studies have been able to successfully identify sentinel lymph nodes in lung tissue and several clinical studies have examined the use of NIR fluorescence imaging systems for SLN mapping in breast and gastric cancer. Promising new nanoparticle technologies, when combined with NIR fluorescence imaging, offer the potential for image-guided treatment of lymph nodes at high risk for tumor recurrence. This review provides a theoretical and empirical framework for developing the next-generation of diagnostic and therapeutic agents for lung cancer. PMID:20226343

  6. Postcolumn fluorescence as an alternative to evaporative light scattering detection for ceramide analysis with gradient elution in non-aqueous reversed-phase liquid chromatography.

    PubMed

    Zhou, J Y; Chaminade, P; Gaudin, K; Prognon, P; Baillet, A; Ferrier, D

    1999-10-22

    Ceramide analysis was developed with gradient elution in non-aqueous reversed-phase liquid chromatography with evaporative light scattering detection (ELSD) or postcolumn fluorescence detection. Fluorescence detection (excitation, 360 nm; emission, 425 nm) after postcolumn formation of mixed assemblies between eluted ceramides and 1,6-diphenyl-1,3,5-hexatriene was developed. In comparison with ELSD, fluorescence detection allows a better detection of the minor species ceramide from ceramide type III (commercial mixture of non-hydroxy fatty acid-sphingosine) and appears to be more sensitive for quantitation of ceramides at low concentrations. The fluorescence response is linear over a wide range of injected amount of ceramide III (expressed as stearoyl-phytosphingosine): 10 ng to 1000 ng. The response of ELSD is non linear but can be linearized in double logarithmic coordinates for calculations over a narrow range, e.g. between 10 to 350 ng ceramide III injected. The lower quantitation limits of these two detectors are similar: 5 ng ceramide III was injected. PMID:10563420

  7. Near-Infrared Light and pH-Responsive Polypyrrole@Polyacrylic acid/Fluorescent Mesoporous Silica Nanoparticles for Imaging and Chemo-Photothermal Cancer Therapy.

    PubMed

    Zhang, Manjie; Wang, Tingting; Zhang, Lingyu; Li, Lu; Wang, Chungang

    2015-11-01

    We have rationally designed a new theranostic agent by coating near-infrared (NIR) light-absorbing polypyrrole (PPY) with poly(acrylic acid) (PAA), in which PAA acts as a nanoreactor and template, followed by growing small fluorescent silica nanoparticles (fSiO2 NPs) inside the PAA networks, resulting in the formation of polypyrrole@polyacrylic acid/fluorescent mesoporous silica (PPY@PAA/fmSiO2 ) core-shell NPs. Meanwhile, DOX-loaded PPY@PAA/fmSiO2 NPs as pH and NIR dual-sensitive drug delivery vehicles were employed for fluorescence imaging and chemo-photothermal synergetic therapy in vitro and in vivo. The results demonstrate that the PPY@PAA/fmSiO2 NPs show high in vivo tumor uptake by the enhanced permeability and retention (EPR) effect after intravenous injection as revealed by in vivo fluorescence imaging, which is very helpful for visualizing the location of the tumor. Moreover, the obtained NPs inhibit tumor growth (95.6 % of tumors were eliminated) because of the combination of chemo-photothermal therapy, which offers a synergistically improved therapeutic outcome compared with the use of either therapy alone. Therefore, the present study provides new insights into developing NIR and pH-stimuli responsive PPY-based multifunctional platform for cancer theranostics. PMID:26494031

  8. Far-red/near-infrared fluorescence light-up probes for specific in vitro and in vivo imaging of a tumour-related protein

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Hua, Yongquan; Hu, Yawen; Fang, Yuan; Ji, Shenglu; Yang, Zhimou; Ou, Caiwen; Kong, Deling; Ding, Dan

    2016-03-01

    As lysosomal protein transmembrane 4 beta (LAPTM4B) is an important biomarker for many solid tumours, development of small-molecule fluorescence light-up probes for detection and imaging of LAPTM4B proteins is particularly valuable. In this work, we reported the design and synthesis of a far-red/near-infrared (FR/NIR) fluorescence light-up probe DBT-2EEGIHGHHIISVG, which could specifically visualize LAPTM4B proteins in cancer cells and tumour-bearing live mice. DBT-2EEGIHGHHIISVG was synthesized by the conjugation of two LAPTM4B-binding peptide ligands (EEGIHGHHIISVG) with one environment-sensitive fluorogen, 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DBT). Owing to the intramolecular charge transfer character of DBT, DBT-2EEGIHGHHIISVG is weakly emissive in aqueous solution, but switches to fluoresce upon LAPTM4B proteins specifically bind to the peptide ligand of the probe, which provide the DBT with hydrophobic microenvironment, greatly reducing its charge transfer effect with water. It is found that DBT-2EEGIHGHHIISVG can achieve targeted imaging of LAPTM4B proteins in HepG2 cancer cells and visualize LAPTM4B protein-expressed tumour tissues of live mice in a selective and high-contrast manner.

  9. Far-red/near-infrared fluorescence light-up probes for specific in vitro and in vivo imaging of a tumour-related protein

    PubMed Central

    Chen, Chao; Hua, Yongquan; Hu, Yawen; Fang, Yuan; Ji, Shenglu; Yang, Zhimou; Ou, Caiwen; Kong, Deling; Ding, Dan

    2016-01-01

    As lysosomal protein transmembrane 4 beta (LAPTM4B) is an important biomarker for many solid tumours, development of small-molecule fluorescence light-up probes for detection and imaging of LAPTM4B proteins is particularly valuable. In this work, we reported the design and synthesis of a far-red/near-infrared (FR/NIR) fluorescence light-up probe DBT-2EEGIHGHHIISVG, which could specifically visualize LAPTM4B proteins in cancer cells and tumour-bearing live mice. DBT-2EEGIHGHHIISVG was synthesized by the conjugation of two LAPTM4B-binding peptide ligands (EEGIHGHHIISVG) with one environment-sensitive fluorogen, 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DBT). Owing to the intramolecular charge transfer character of DBT, DBT-2EEGIHGHHIISVG is weakly emissive in aqueous solution, but switches to fluoresce upon LAPTM4B proteins specifically bind to the peptide ligand of the probe, which provide the DBT with hydrophobic microenvironment, greatly reducing its charge transfer effect with water. It is found that DBT-2EEGIHGHHIISVG can achieve targeted imaging of LAPTM4B proteins in HepG2 cancer cells and visualize LAPTM4B protein-expressed tumour tissues of live mice in a selective and high-contrast manner. PMID:26984064

  10. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs. PMID:26536570

  11. Fluorescent filtered electrophosphorescence

    DOEpatents

    Forrest, Stephen; Sun, Yiru; Giebink, Noel; Thompson, Mark E.

    2010-08-03

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

  12. Fluorescent filtered electrophosphorescence

    DOEpatents

    Forrest, Stephen R.; Sun, Yiru; Giebink, Noel; Thompson, Mark E.

    2009-01-06

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

  13. Fluorescent eye test (image)

    MedlinePlus

    The fluorescent eye test is useful in determining if there is a scratch or other problem with the surface ... has thoroughly covered the eye a cobalt blue light is then directed on the eye. The light ...

  14. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

    PubMed Central

    Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

    2013-01-01

    The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years. PMID:23955041

  15. Development of a multivariate light-induced fluorescence (LIF) PAT tool for in-line quantitative analysis of pharmaceutical granules in a V-blender.

    PubMed

    Guay, Jean-Maxime; Lapointe-Garant, Pierre-Philippe; Gosselin, Ryan; Simard, Jean-Sébastien; Abatzoglou, Nicolas

    2014-04-01

    Process analytical technologies (PAT) enable process insight, process control and real-time testing. Light-induced fluorescence (LIF) spectroscopy is especially well suited for low-concentration ingredients as, in many cases, it is the most sensitive probe of the in-line PAT toolbox. This study is aimed at verifying the applicability of a multivariate LIF analyzer to monitor granulated powder blends in industrial settings. Its targets are to: (1) evaluate the critical parameters of powders to obtain robust, precise and accurate concentration predictions and (2) assess technology performance for in-line monitoring of blending operations. Varying dye properties, moisture levels and particle sizes have been shown to have the most significant impact on fluorescence emission. Reliable quantitative models can be obtained by controlling and/or mitigating these factors. PMID:24373731

  16. Daily light use efficiency in a cornfield can be related to the canopy red/far-red fluorescence ratio and leaf light use efficiency across a growing season

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In multiple years (2008-2013), we collected canopy and leaf fluorescence, photosynthesis, hyperspectral reflectance spectra, and biophysical measurements along transects within a USDA/Beltsville experimental cornfield treated with optimal nitrogen application (100%N) and which has an eddy covariance...

  17. Direct observation of a resolvable spin separation in the spin Hall effect of light at an air-glass interface

    SciTech Connect

    Ren, Jin-Li; Wang, Bo; Xiao, Yun-Feng; Gong, Qihuang; Li, Yan

    2015-09-14

    We theoretically and experimentally demonstrate that it is possible to directly observe the resolvable spin separation in the spin Hall effect of light at an air-glass interface by choosing optimal parameters. When a P-polarized light with a beam waist of 10 μm is incident around Brewster's angle, the two spin components of the reflected beam can be completely separated by eliminating the influence of the in-plane wavevector spread. This not only obviously reveals the strong impacts of the polarization state, the incident angle, the beam waist, and the in-plane wavevector spread, but also intuitively visualizes the observation of the spin Hall effect of light.

  18. Responsive polymer-fluorescent carbon nanoparticle hybrid nanogels for optical temperature sensing, near-infrared light-responsive drug release, and tumor cell imaging.

    PubMed

    Wang, Hui; Ke, Fuyou; Mararenko, Anton; Wei, Zengyan; Banerjee, Probal; Zhou, Shuiqin

    2014-07-01

    Fluorescent carbon nanoparticles (FCNPs) have been successfully immobilized into poly(N-isopropylacrylamide-co-acrylamide) [poly(NIPAM-AAm)] nanogels based on one-pot precipitation copolymerization of NIPAM monomers with hydrogen bonded FCNP-AAm complex monomers in water. The resultant poly(NIPAM-AAm)-FCNP hybrid nanogels can combine functions from each building block for fluorescent temperature sensing, cell imaging, and near-infrared (NIR) light responsive drug delivery. The FCNPs in the hybrid nanogels not only emit bright and stable photoluminescence (PL) and exhibit up-conversion PL properties, but also increase the loading capacity of the nanogels for curcumin drug molecules. The reversible thermo-responsive swelling/shrinking transition of the poly(NIPAM-AAm) nanogel can not only modify the physicochemical environment of the FCNPs to manipulate the PL intensity for sensing the environmental temperature change, but also regulate the releasing rate of the loaded anticancer drug. In addition, the FCNPs embedded in the nanogels can convert the NIR light to heat, thus an exogenous NIR irradiation can further accelerate the drug release and enhance the therapeutic efficacy. The hybrid nanogels can overcome cellular barriers to enter the intracellular region and light up the mouse melanoma B16F10 cells upon laser excitation. The demonstrated hybrid nanogels with nontoxic and optically active FCNPs immobilized in responsive polymer nanogels are promising for the development of a new generation of multifunctional materials for biomedical applications. PMID:24881520

  19. Determination of free amino acids in African gourd seed milks by capillary electrophoresis with light-emitting diode induced fluorescence and laser-induced fluorescence detection.

    PubMed

    Enzonga, Josiane; Ong-Meang, Varravaddheay; Couderc, François; Boutonnet, Audrey; Poinsot, Véréna; Tsieri, Michel Mvoula; Silou, Thomas; Bouajila, Jalloul

    2013-09-01

    A CE technique coupled to LIF detection (488 nm) or LED-induced fluorescence detection (470 nm) has been evaluated to acquire a cheap way to analyze amino acids (AAs) whilst maintaining the best sensitivity. To quantitate AAs in milk of Cucurbitaceae of Sub-Saharan Africa, they were labeled with FITC. We used an optimized separation buffer composed of 30 mM boric acid buffer adjusted to pH 9.3 with NaOH (1 M) containing 12 mM SDS and 5% ethylene glycol v/v; prior to the injections, the derivatized samples are diluted 100 times. The LOQs in the sample are Arg: 1.1 μM, Ala: 3.5 μM, and Glu 8.9 μM. Cucumeropsis mannii (CM) Naudin and Citrullus lanatus (CL) are vegetable sources rich in proteins and AAs of high quality. Our analyses have led to the identification of 11 AAs in CL and CM milks. Phe, Trp, and Ala are predominant in the two types of lyophilized milks, while Asp and Val demonstrate very low contents. Six essential AAs (Phe, Thr, Val, Trp, Ile, and Leu) are present in both types of extracts, but lysine was not detected, indicating that this AA is missing in gourd milk. These results should be useful in efforts to complement or replace very expensive cow milk or the less-appreciated soya milk with milk from available local agroressources. PMID:23857426

  20. Microstructured Air Cavities as High-Index Contrast Substrates with Strong Diffraction for Light-Emitting Diodes.

    PubMed

    Moon, Yoon-Jong; Moon, Daeyoung; Jang, Jeonghwan; Na, Jin-Young; Song, Jung-Hwan; Seo, Min-Kyo; Kim, Sunghee; Bae, Dukkyu; Park, Eun Hyun; Park, Yongjo; Kim, Sun-Kyung; Yoon, Euijoon

    2016-05-11

    Two-dimensional high-index-contrast dielectric gratings exhibit unconventional transmission and reflection due to their morphologies. For light-emitting devices, these characteristics help guided modes defeat total internal reflections, thereby enhancing the outcoupling efficiency into an ambient medium. However, the outcoupling ability is typically impeded by the limited index contrast given by pattern media. Here, we report strong-diffraction, high-index-contrast cavity engineered substrates (CESs) in which hexagonally arranged hemispherical air cavities are covered with a 80 nm thick crystallized alumina shell. Wavelength-resolved diffraction measurements and Fourier analysis on GaN-grown CESs reveal that the high-index-contrast air/alumina core/shell patterns lead to dramatic excitation of the low-order diffraction modes. Large-area (1075 × 750 μm(2)) blue-emitting InGaN/GaN light-emitting diodes (LEDs) fabricated on a 3 μm pitch CES exhibit ∼39% enhancement in the optical power compared to state-of-the-art, patterned-sapphire-substrate LEDs, while preserving all of the electrical metrics that are relevant to LED devices. Full-vectorial simulations quantitatively demonstrate the enhanced optical power of CES LEDs and show a progressive increase in the extraction efficiency as the air cavity volume is expanded. This trend in light extraction is observed for both lateral- and flip-chip-geometry LEDs. Measurements of far-field profiles indicate a substantial beaming effect for CES LEDs, despite their few-micron-pitch pattern. Near-to-far-field transformation simulations and polarization analysis demonstrate that the improved extraction efficiency of CES LEDs is ascribed to the increase in emissions via the top escape route and to the extraction of transverse-magnetic polarized light. PMID:27045458

  1. High-power-efficiency hybrid white organic light-emitting diodes with a single emitting layer doped with blue delayed fluorescent and yellow phosphorescent emitters

    NASA Astrophysics Data System (ADS)

    Song, Wook; Lee, Jun Yeob

    2015-09-01

    High-efficiency hybrid white organic light-emitting diodes (HWOLEDs) with a blue thermally activated delayed fluorescent (TADF) emitter and a yellow phosphorescent emitter doped in a single emitting layer were developed. Exciton harvesting by the blue TADF and yellow phosphorescent emitters rendered both singlet and triplet excitons to contribute to the white emission, which leads to a high quantum efficiency of 22.4% and a power efficiency of 60.3 lm W-1 in the HWOLEDs. In addition, the electroluminescence spectra of the HWOLEDs were kept stable from 100 cd m-2 to 5, 000 cd m-2.

  2. Above 20% external quantum efficiency in novel hybrid white organic light-emitting diodes having green thermally activated delayed fluorescent emitter

    NASA Astrophysics Data System (ADS)

    Kim, Bo Seong; Yook, Kyoung Soo; Lee, Jun Yeob

    2014-08-01

    High efficiency hybrid type white organic light-emitting diodes (WOLEDs) combining a green thermally activated delayed fluorescent (TADF) emitting material with red/blue phosphorescent emitting materials were developed by manipulating the device architecture of WOLEDs. Energy transfer between a blue phosphorescent emitting material and a green TADF emitter was efficient and could be managed by controlling the doping concentration of emitters. A high quantum efficiency above 20% was achieved in the hybrid WOLEDs by optimizing the device structure of the hybrid type WOLEDs for the first time and the device performances of the hybrid WOLEDs were comparable to those of all phosphorescent WOLEDs.

  3. Emissions of an AVCO Lycoming 0-320-DIAD air cooled light aircraft engine as a function of fuel-air ratio, timing, and air temperature and humidity

    NASA Technical Reports Server (NTRS)

    Meng, P. R.; Skorobatckyi, M.; Cosgrove, D. V.; Kempke, E. E., Jr.

    1976-01-01

    A carbureted aircraft engine was operated over a range of test conditions to establish the exhaust levels over the EPA seven-mode emissions cycle. Baseline (full rich production limit) exhaust emissions at an induction air temperature of 59 F and near zero relative humidity were 90 percent of the EPA standard for HC, 35 percent for NOx, and 161 percent for CO. Changes in ignition timing around the standard 25 deg BTDC from 30 deg BTDC to 20 deg BTDC had little effect on the exhaust emissions. Retarding the timing to 15 deg BTDC increased both the HC and CO emissions and decreased NOx emissions. HC and CO emissions decreased as the carburetor was leaned out, while NOx emissions increased. The EPA emission standards were marginally achieved at two leanout conditions. Variations in the quantity of cooling air flow over the engine had no effect on exhaust emissions. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased.

  4. Do-It-Yourself Air Sensors – Exploring the Atmosphere and Turning on Light Bulbs!?

    EPA Science Inventory

    These are educational slides that will be presented in a webinar to the National Science Teachers Association. Topics covered include general air quality, current EPA research, and EPA's particle sensor kit that is a classroom activity.

  5. Detection of Silver Nanoparticles in Cells by Flow Cytometry Using Light Scattering and Far-red Fluorescence

    EPA Science Inventory

    The cellular uptake of different sized silver nanoparticles (l0 nm, 50 nm, and 75nm) coated with polyvinylpyrrolidone (PVP) or citrate in ARPE-19 cells following 24 hour incubation was detected by side scatter through the use of a flow cytometer. A large far red fluorescence sign...

  6. Bladder cancer detection by fluorescence imaging with Hexvix: optimization of the excitation light during high magnification cystoscopy

    NASA Astrophysics Data System (ADS)

    Lovisa, Blaise; Jichlinski, Patrice; Aymon, Daniela; Weber, Bernd-Claus; van den Bergh, Hubert; Wagnières, Georges

    2009-07-01

    Fluorescence cystoscopy has been recently acknowledged as a useful method to detect early superficial bladder cancer, even flat lesions. After the instillation of hexaminolevulinic acid (Hexvix®) in the bladder for about an hour, photoactivable porphyrins (PaP), mainly protoporphyrin IX (PpIX) accumulate in the cancerous cells. Although we observe a selective production of PpIX and an outstanding sensitivity of this method, false positive (FP) lesions negatively impact its specificity. Carcinogenesis often combines with angiogenesis, and thus changes in vascular architecture. Therefore, the visualization of the vascular modifications on the fluorescence positive sites is likely to differentiate false and true positive (TP). New methods including high magnification (HM) cystoscopy are being investigated by our group, and will yield a reduced number of biopsies and a better characterization of the fluorescence positive sites. In this study, we are using a dedicated rigid cystoscope, allowing conventional magnification during "macroscopic" observation, as well as image acquisition with HM when the endoscope is in contact with the tissue. Each observed site is biopsied and described by histopathological analysis. The vascular organization (tortuosity, vascular loops, vascular area and diameter) of the fluorescence positive sites was characterized in situ. Intrinsic contrast between the vessels and the tissue was enhanced with an optimization of the spectral design. Preliminary results are presented here.

  7. A versatile thermally activated delayed fluorescence emitter for both highly efficient doped and non-doped organic light emitting devices.

    PubMed

    Tsai, Wei-Lung; Huang, Ming-Hao; Lee, Wei-Kai; Hsu, Yi-Jiun; Pan, Kuan-Chung; Huang, Yi-Hsiang; Ting, Hao-Chun; Sarma, Monima; Ho, Yu-Yi; Hu, Hung-Chieh; Chen, Chung-Chia; Lee, Meng-Ting; Wong, Ken-Tsung; Wu, Chung-Chih

    2015-09-14

    A thermally activated delayed fluorescent (TADF) emitter (DMAC-TRZ) was reported either as the emitting dopant in a host or as the non-doped (neat) emitting layer to achieve high EL EQEs of up to 26.5% and 20% in OLEDs, respectively. PMID:26226072

  8. Effect of Intake Air Filter Condition on Light-Duty Gasoline Vehicles

    SciTech Connect

    Thomas, John F; Huff, Shean P; West, Brian H; Norman, Kevin M

    2012-01-01

    Proper maintenance can help vehicles perform as designed, positively affecting fuel economy, emissions, and the overall drivability. This effort investigates the effect of one maintenance factor, intake air filter replacement, with primary focus on vehicle fuel economy, but also examining emissions and performance. Older studies, dealing with carbureted gasoline vehicles, have indicated that replacing a clogged or dirty air filter can improve vehicle fuel economy and conversely that a dirty air filter can be significantly detrimental to fuel economy. The effect of clogged air filters on the fuel economy, acceleration and emissions of five gasoline fueled vehicles is examined. Four of these were modern vehicles, featuring closed-loop control and ranging in model year from 2003 to 2007. Three vehicles were powered by naturally aspirated, port fuel injection (PFI) engines of differing size and cylinder configuration: an inline 4, a V6 and a V8. A turbocharged inline 4-cylinder gasoline direct injection (GDI) engine powered vehicle was the fourth modern gasoline vehicle tested. A vintage 1972 vehicle equipped with a carburetor (open-loop control) was also examined. Results reveal insignificant fuel economy and emissions sensitivity of modern vehicles to air filter condition, but measureable effects on the 1972 vehicle. All vehicles experienced a measured acceleration performance penalty with clogged intake air filters.

  9. Application of laser light scattering for determination of the border aerosol-air in a specialized physical laboratory setup

    NASA Astrophysics Data System (ADS)

    Damov, K. S.; Iliev, M. T.

    2016-02-01

    The current article examines the application of laser light scattering in a specialized laboratory setup. It is used for determination of the kinematic viscosity and mass density of Aerodispersed Systems formed in Limited Volume (High Concentration Aerosols) by the method of free flow out. The measurement chamber is first filled with the investigated aerosol. After a predetermined delay time the aerosol is allowed to flow out through a calibrated pipe with fixed size located few centimetres above the chamber's bottom. The lowering of the upper border aerosol-air is continuously scanned using a laser beam directed along the axis of the cylindrical chamber. The kinematic viscosity and mass density of the investigated aerosol phase are calculated by formulas obtained by the authors. The suggested application of laser light scattering led to higher accuracy of the determination the position of aerosol-air border, thence the certainty of this method. This improvement allowed the use of computer controlled optoelectronic setting. The use of laser light scattering significantly improves the method for determination of the kinematic viscosity and mass density of Aerodispersed Systems formed in Limited Volume.

  10. A high performance fluorescent white organic light-emitting device and its optimization for full-colour display

    NASA Astrophysics Data System (ADS)

    Li, Jiang; Duan, Yu; Zhao, Yi; Li, Xinhong; Li, Chuannan; Hou, Jingying; Liu, Shiyong

    2006-02-01

    A white organic light emitting diode (OLED) was fabricated in which blue emission host 9,10-di(2-naphthyl)anthracene (ADN) doped with an orange emission dye (rubrene) was used to generate bright, high efficiency white light. A large amount of work was done to study the emission mechanism of a rubrene-doped device. Finally, to get optimized EL spectra, we introduced a green light which is emitted from tris(8-hydroxy-quinoline) aluminium (Alq3), the electron transport material, into the emission of white light.

  11. Light Reflector

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Ultra Sales, Inc.'s fluorescent lighting fixture gets a boost in reflectivity through installation of Lightdriver, a thin tough thermoplastic film plated with aluminum, capable of reflecting 95 percent of visible light striking it. Lightdriver increases brightness without adding bulbs, and allows energy savings by removing some bulbs because the mirrorlike surface cuts light loss generally occasioned by conventional low reflectivity white painted surface above the bulbs in many fluorescent fixtures. Forty-five percent reduction in lighting electricity is attainable.

  12. Effect of different solvents on the performance of organic light-emitting device based on red-fluorescent ACY dye by spin coating method

    NASA Astrophysics Data System (ADS)

    Yu, Shuangjiang; Yu, Junsheng; Wang, Hong; Jiang, Yadong

    2010-10-01

    A small-molecular red-fluorescent dye of [7-diethylamino-3-(2-thienyl)chronmen-2-ylidene]-2,2-dicyanoviny-lamine (ACY) has been blended into blue-emitting poly(N-vinylcarbazole) (PVK) by using different solvents of chloroform and 1,2-dichloroethane. Photoluminescence characteristic of solvent effects were investigated mainly from the aspect of solvent polarity. To demonstrate the solvent effects in organic light emitting devices (OLEDs), devices with a structure of indium-tin-oxide (ITO)/PVK: ACY (x wt %)/tris(8-quinolinolato) aluminum (Alq3)/Mg: Ag were fabricated, in which the weight doping ratios are x = 0.3, 0.5 and 0.7. Using spin coating method, a blending system of PVK: ACY is dissolved in both chloroform and 1,2-dichloroethane with various doping concentrations. As a result, by choosing chloroform as solvent, a high electroluminescent (EL) performance device with a maximum luminance of 7698 cd/m2 at a driving voltage of 15.5 V was obtained, with a concentration proportion of PVK: ACY at 1000: 7. In the EL spectra of the OLEDs, red and green fluorescence of ACY and Alq3 were detected. It was found that by using 1,2-dichloroethane as a solvent, fluorescent quenching emerged with the enhancement of doping concentration. Energy transfer and Alq3 cations quencher theories were used to discuss different solvent effects on OLEDs.

  13. Use of fluorescence signals generated by elastic scattering under monochromatic incident light for determining the scattering efficiencies of various plasmonic nanoparticles.

    PubMed

    Song, Ji Eun; Park, Ji Hoon; La, Ju A; Park, Seyeon; Jeong, Min Kuk; Cho, Eun Chul

    2016-08-01

    We present a route that estimates the scattering/absorption characteristics of plasmonic nanoparticles by using fluorescence and UV-visible spectroscopy. Because elastic scattering of nanoparticles caused by a monochromatic incident light is reflected in fluorescence emission spectra when recording at the excitation wavelength, the scattering intensities at the excitation wavelength during fluorescence emission scans are used to compare the scattering characteristics of various plasmonic nanoparticles under conditions where the extinction values of all of the nanoparticles are kept constant at this wavelength. For the two excitation wavelengths (519 and 560 nm) we investigated, the scattering intensities of spherical gold nanoparticles increase with increasing size (15, 33, 51, 73, and 103 nm in diameter). These results are correlated with the nanoparticles' scattering efficiencies (the ratios of scattering to the extinction cross-sections), which are theoretically calculated in the literature using Mie theory. Then, linear calibration equations at each wavelength are derived to estimate the scattering efficiencies of two Au nanorods, Au nanocages, and spherical Ag nanoparticles (15, 25, 37, and 62 nm). The values are very comparable with literature values. For various purposes such as biomedicine and optoelectronics, the present method could be beneficial to those who wish to easily compare and determine the scattering characteristics of various plasmonic nanoparticles at a certain wavelength by using commercially-available spectroscopic techniques. PMID:27215291

  14. Effects of sodium and magnesium cations on the "dark-" and light-induced chlorophyll a fluorescence yields in sucrose-washed spinach chloroplasts.

    PubMed

    Wydrzynski, T; Gross, E L; Govindjee

    1975-01-31

    The effects of Na plus and Mg-2 plus on the "dark" level (O level) and light-induced (P level) fluorescence in sucrose-washed spinach clhoroplasts were studied. Low concentrations of NaCl (2-10 mM) cause a significant decrease in both the O and P levels in the chlorophyll fluorescence transient. The effect on the O level may reflect changes in the bulk chlorophyll a. At 77 degrees K NaCl increases the F735/F685 emission peak ratio in dark-adapted and preilluminated chloroplasts, but has no significant effect on this ratio in sucrose-washed Photosystem II particles. This evidence is consistent with a sodium-induced excitation-energy distribution in favor of Photosystem I. In the presence of MgCl2, with or without NaCl, there is a slight decrease in the O and P level fluorescence as compared with the salt-free control, but an increase as compared with the NaCl-treated sample. Magnesium appears to override the sodium-induced changes. At low temperatures in chloroplasts and Photosystem II particles, MgCl2 has different effects on the F735/F685 ratio apparently depending on the state of the membrane. Magnesium, however, always induces an increase in the F695/F685 ratio. These results suggest that magnesium may influence Photosystem II reaction centers as well as energy distribution between the two photosystems. PMID:1125217

  15. Global spectral-kinetic analysis of room temperature chlorophyll a fluorescence from light-harvesting antenna mutants of barley.

    PubMed Central

    Gilmor, A M; Itoh, S; Govindjee

    2000-01-01

    This study presents a novel measurement, and simulation, of the time-resolved room temperature chlorophyll a fluorescence emission spectra from leaves of the barley wild-type and chlorophyll-b-deficient chlorina (clo) f2 and f104 mutants. The primary data were collected with a streak-camera-based picosecond-pulsed fluorometer that simultaneously records the spectral distribution and time dependence of the fluorescence decay. A new global spectral-kinetic analysis programme method, termed the double convolution integral (DCI) method, was developed to convolve the exciting laser pulse shape with a multimodal-distributed decay profile function that is again convolved with the spectral emission band amplitude functions. We report several key results obtained by the simultaneous spectral-kinetic acquisition and DCI methods. First, under conditions of dark-level fluorescence, when photosystem II (PS II) photochemistry is at a maximum at room temperature, both the clo f2 and clo f104 mutants exhibit very similar PS II spectral-decay contours as the wild-type (wt), with the main band centred around 685 nm. Second, dark-level fluorescence is strongly influenced beyond 700 nm by broad emission bands from PS I, and its associated antennae proteins, which exhibit much more rapid decay kinetics and strong integrated amplitudes. In particular a 705-720 nm band is present in all three samples, with a 710 nm band predominating in the clo f2 leaves. When the PS II photochemistry becomes inhibited, maximizing the fluorescence yield, both the clo f104 mutant and the wt exhibit lifetime increases for their major distribution modes from the minimal 205-500 ps range to the maximal 1500-2500 ps range for both the 685 nm and 740 nm bands. The clo f2 mutant, however, exhibits several unique spectral-kinetic properties, attributed to its unique PS I antennae and thylakoid structure, indicating changes in both PS II fluorescence reabsorption and PS II to PS I energy transfer pathways

  16. Measurement of Fluorescence Spectra from Ambient Aerosol Particles Using Laser-induced Fluorescence Technique

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.; Nakamura, T.; Moteki, N.; Takegawa, N.

    2011-12-01

    To obtain the information of composition of organic aerosol particles in atmosphere, we developed an instrument using laser-induced fluorescence (LIF) technique. To measure the fluorescence from a particle, we employed two lasers. Scattering light signal derived from a single particle upon crossing the 635nm-CW laser triggers the 266nm-pulsed laser to excite the particle. Fluorescence from the particle in the wavelength range 300-600nm is spectrally dispersed by a grating spectrometer and then detected by a 32-Ch photo-multiplier tube(PMT). The aerosol stream is surrounded by a coaxial sheath air flow and delivered to the optical chamber at atmospheric pressure. Using PSL particles with known sizes, we made a calibration curve to estimate particle size from scattering light intensity. With the current setup of the instrument we are able to detect both scattering and fluorescence from particles whose diameters are larger than 0.5um. Our system was able to differentiate particles composed of mono-aromatic species (e.g. Tryptophan) from those of Riboflavin, by their different fluorescence wavelengths. Also, measurements of fluorescence spectra of ambient particles were demonstrated in our campus in Yokosuka city, facing Tokyo bay in Japan. We obtained several types of florescence spectra in the 8 hours. Classification of the measured fluorescence spectra will be discussed in the presentation.

  17. High-throughput profiling of tissue and tissue model microarrays: Combined transmitted light and 3-color fluorescence digital pathology

    PubMed Central

    Nederlof, Michel; Watanabe, Shigeo; Burnip, Bill; Taylor, D. Lansing; Critchley-Thorne, Rebecca

    2011-01-01

    For many years pathologists have used Hematoxylin and Eosin (H&E), single marker immunohistochemistry (IHC) and in situ hybridization with manual analysis by microscopy or at best simple digital imaging. There is a growing trend to update pathology to a digital workflow to improve objectivity and productivity, as has been done in radiology. There is also a need for tissue-based multivariate biomarker assays to improve the accuracy of diagnostic, prognostic, and predictive testing. Multivariate tests are not compatible with the traditional single marker, manual analysis pathology methods but instead require a digital platform with brightfield and fluorescence imaging, quantitative image analysis, and informatics. Here we describe the use of the Hamamatsu NanoZoomer Digital Pathology slide scanner with HCImage software for combined brightfield and multiplexed fluorescence biomarker analysis and highlight its applications in biomarker research and pathology testing. This combined approach will be an important aid to pathologists in making critical diagnoses. PMID:22200032

  18. A rapidly photo-activatable light-up fluorescent nucleoside and its application in DNA base variation sensing.

    PubMed

    He, Zhiyong; Chen, Yuqi; Wang, Yafen; Wang, Jiaqi; Mo, Jing; Fu, Boshi; Wang, Zijing; Du, Yuhao; Zhou, Xiang

    2016-06-30

    A new DNA building block (d(Tet)U) bearing a tetrazole and allyloxy group at N-phenyl ring linked through an aminopropynyl linker to the 5-position of 2'-deoxyuridine was synthesized. The modified DNA can be lit up via a photoinduced intramolecular tetrazole-alkene cycloaddition reaction, but quenched when the fully-matched double strand is formed. This conspicuous difference in fluorescence could open a door for DNA single nucleotide polymorphism (SNP) typing. PMID:27315545

  19. Reaction dynamics during pulsed light activation of ATX-S10 Na(II)-sensitized cell cultures: analysis based on fluorescence-oxygen diagram

    NASA Astrophysics Data System (ADS)

    Kawauchi, Satoko; Sato, Shunichi; Morimoto, Yuji; Kikuchi, Makoto

    2005-04-01

    To elucidate the mechanism of photosensitization with pulsed light excitation, we previously introduced fluorescence-oxygen diagram that shows the correlation between photochemical oxygen consumption and photobleaching during a treatment (Kawauchi et al., Photochem. Photobiol., 80, 216-223, 2004). In pulsed photodynamic treatment of A549 cells with ATX-S10"Na(II), the diagrams for treatments at relatively high repetition rates of 10 and 30 Hz showed the complex behaviors of photochemical reaction; photobleaching initially occurred with oxygen consumption but it was switched to oxygen-independent photobleaching, which was followed by a secondary oxygen-consuming regime. In this study, fluorescence microscopy revealed that for treatments at 10 and 30 Hz, subcellular fluorescence distribution of ATX-S10×Na(II) changed drastically from the high-intensity spotty patterns showing lysosomal accumulation to the diffusive patterns within the cytosol during certain ranges of total light dose. These ranges were found to coincide with those in which oxygen-independent reaction appeared. These findings suggest that the sensitizer started to be redistributed from lysosomes to the cytosol during the oxygen-independent reaction regime. On the other hand, at 5 Hz, such reaction switching was not clearly seen during whole irradiation period in the diagram; this was consistent with the observation that sensitizer redistribution efficiently occurred even in the early phase of irradiation. The appearance of oxygen-independent reaction at the higher repetition rates may be caused by high local concentration of the sensitizer and the resultant low concentration of oxygen in the reaction sites due to the shorter pulse-to-pulse time intervals. In pulsed photodynamic treatment, pulse frequency is an important parameter that affects the intracellular kinetics of the sensitizer and hence the photochemical reaction dynamics.

  20. Stability and transient effects in nanosecond ultraviolet light filaments in air.

    PubMed

    Niday, Thomas A; Wright, Ewan M; Kolesik, Miroslav; Moloney, Jerry V

    2005-07-01

    We investigate the transient behavior and stability of nanosecond duration ultraviolet pulses propagating in air. Both the transient behavior arising from the finite pulse duration and the modulational instability, are found to cause pulses to fragment over lengths on the scale of meters. We discuss the theoretical and experimental implications of the instability and transient effects for long duration pulse propagating in air and generating filaments. In particular, our results imply that continuous-wave models are very limited when used to predict dynamical properties of pulse propagation. PMID:16090118