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.

  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. Nitrogen fluorescence in air for observing extensive air showers

    NASA Astrophysics Data System (ADS)

    Keilhauer, B.; Bohacova, M.; Fraga, M.; Matthews, J.; Sakaki, N.; Tameda, Y.; Tsunesada, Y.; Ulrich, A.

    2013-06-01

    Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of Air Fluorescence Workshops commenced in 2002. At the 8th Air Fluorescence Workshop 2011, it was suggested to develop a common way of describing the nitrogen fluorescence for application to air shower observations. Here, first analyses for a common treatment of the major dependences of the emission procedure are presented. Aspects like the contributions at different wavelengths, the dependence on pressure as it is decreasing with increasing altitude in the atmosphere, the temperature dependence, in particular that of the collisional cross sections between molecules involved, and the collisional de-excitation by water vapor are discussed.

  4. Application of CORSIKA Simulation Code to Study Lateral and Longitudinal Distribution of Fluorescence Light in Cosmic Ray Extensive Air Showers

    NASA Astrophysics Data System (ADS)

    Bagheri, Zahra; Davoudifar, Pantea; Rastegarzadeh, Gohar; Shayan, Milad

    2017-03-01

    In this paper, we used CORSIKA code to understand the characteristics of cosmic ray induced showers at extremely high energy as a function of energy, detector distance to shower axis, number, and density of secondary charged particles and the nature particle producing the shower. Based on the standard properties of the atmosphere, lateral and longitudinal development of the shower for photons and electrons has been investigated. Fluorescent light has been collected by the detector for protons, helium, oxygen, silicon, calcium and iron primary cosmic rays in different energies. So we have obtained a number of electrons per unit area, distance to the shower axis, shape function of particles density, percentage of fluorescent light, lateral distribution of energy dissipated in the atmosphere and visual field angle of detector as well as size of the shower image. We have also shown that location of highest percentage of fluorescence light is directly proportional to atomic number of elements. Also we have shown when the distance from shower axis increases and the shape function of particles density decreases severely. At the first stages of development, shower axis distance from detector is high and visual field angle is small; then with shower moving toward the Earth, angle increases. Overall, in higher energies, the fluorescent light method has more efficiency. The paper provides standard calibration lines for high energy showers which can be used to determine the nature of the particles.

  5. 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)

  6. 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.

  7. 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

  8. D-light for laparoscopic fluorescence diagnosis

    NASA Astrophysics Data System (ADS)

    Gahlen, Johannes; Laubach, Hans-Heinrich; Stern, Josef; Pressmar, Jochen; Pietschmann, Mathias; Herfarth, Christian

    1999-07-01

    To evaluate the role of ALA induced fluorescence diagnosis in laparoscopic surgery, we induced peritoneal carcinosis in rats by multilocular intraabdominal tumorcell implantation (CC531). The animals were photosensitized by intraabdominal ALA lavage. Laparoscopy was performed with both, conventional white and then blue light (D-Light, KARL STORZ Germany) excitation. Laparoscopy with conventional white light showed peritoneal carcinoma foci from 0.1 to 2 cm in diameter. All macroscopically visible tumors (n equals 142) were fluorescence positive after laparoscopic blue light excitation. In addition, 30 laparoscopic not visible (white light) tumors showed fluorescence and were histologically confirmed as colon carcinoma metastases. We conclude that only ALA induced laparoscopic fluorescence detection after blue light excitation is the adequate method to detect the entire extent of the intraabdominal tumor spread. Fluorescence laparoscopy is essential for laparoscopic staging of colorectal cancer because of a higher rate of cancer foci detection.

  9. Compact Fluorescent Light Bulbs (CFLs)

    EPA Pesticide Factsheets

    CFLs can help you save money, use less energy, reduce light bulb changes, and lower greenhouse gas emissions, which lead to climate change. Learn about proper cleanup, recycling and disposal, labels, mercury, and UV radiation.

  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. Sustainable LED Fluorescent Light Replacement Technology

    SciTech Connect

    None, None

    2011-09-30

    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 comparable

  12. 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

  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. 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

  16. 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.

  17. Photocatalytic oxidation of volatile organic compounds using fluorescent visible light.

    PubMed

    Chapuis, Yannick; Klvana, Danilo; Guy, Christophe; Kirchnerova, Jitka

    2002-07-01

    Photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a highly attractive alternative technology for purification and deodorization of indoor air. The main objectives of this study were to demonstrate that a common fluorescent visible light (FVL) lamp can be used to effectively remove by PCO low concentrations of VOCs from slightly contaminated air and to provide some fundamental and technical details on the process. The target VOC was n-butanol, which is a standard reference odorant. Its PCO was studied under a long residence time in a 3.7-L cylindrical reactor with commercial titanium dioxide (TiO2) as the reference photocatalyst and using mostly FVL for illumination. For comparison only, a UV (black) light lamp was used. The gas-phase products were detected and quantified online by gas chromatography (GC). The effects of reactor residence time, of inlet concentration, and of the relative light intensity on the efficiency of the process were also evaluated. At a high n-butanol concentration (0.1 vol %), butanal and propanal were identified as the intermediate products of the process; ethanal appeared when the initial concentration was < or = 850 ppm(v). This indicates that PCO leading to CO2 and H2O is relatively slow and proceeds in a stepwise manner. Although the efficiency of the process with an FVL lamp was significantly lower than when using a UV black light, complete PCO of low concentrations was achieved for 100 ppm(v). In a search for a material with photoactivation extended to higher wavelengths or increased photoactivity, several samples of transition metal- or silver ion-doped (2 atomic %) TiO2 as well as SrTi(1-x-)Fe(x)O3 (x = 0.1 and 0.15) perovskites were included in the study. None of these materials was more active than pure TiO2. The results of this study open new horizons in the area of in door air quality (IAQ) control.

  18. 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.

  19. 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.

  20. RNA fluorescence with light-up aptamers

    NASA Astrophysics Data System (ADS)

    Ouellet, Jonathan

    2016-06-01

    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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Pulsed-light imaging for fluorescence guided surgery under normal room lighting.

    PubMed

    Sexton, Kristian; Davis, Scott C; McClatchy, David; Valdes, Pablo A; Kanick, Stephen C; Paulsen, Keith D; Roberts, David W; Pogue, Brian W

    2013-09-01

    Fluorescence guided surgery (FGS) is an emerging technology that has demonstrated improved surgical outcomes. However, dim lighting conditions required by current FGS systems are disruptive to standard surgical workflow. We present a novel FGS system capable of imaging fluorescence under normal room light by using pulsed excitation and gated acquisition. Images from tissue-simulating phantoms confirm visual detection down to 0.25 μM of protoporphyrin IX under 125 μW/cm2 of ambient light, more than an order of magnitude lower than that measured with the Zeiss Pentero in the dark. Resection of orthotopic brain tumors in mice also suggests that the pulsed-light system provides superior sensitivity in vivo.

  13. Detection of Ionizing Radiation using Solar Blind Air Fluorescence

    DTIC Science & Technology

    2013-06-01

    14 16 Figure 1.2: Geant4 simulation of the solar blind photon flux from 1010 decays of Am241 viewed by a 40 cm diameter detector at a distance of 10 m...discharges and other sources, sufficiently low that it will not interfere with the operation of a solar blind radiological detector ? UNCLASSIFIED iii DSTO...Figures 1.2 through 1.4 show simulated solar blind photon air fluorescence emission from common radiological sources (Am240,Cs137 and Sr90). In each

  14. Simulating the illuminance and the efficiency of the LED and fluorescent lights used in indoor lighting design.

    PubMed

    Tsuei, Chih-Hsuan; Pen, Jui-Wen; Sun, Wen-Shing

    2008-11-10

    In this study we simulate the illuminance and efficiency of four different types of reflector LED and fluorescent light sources for interior illumination. According to our calculation results of the examination of simulations and real situations, we find that the LEDs do perform better than fluorescent lights. We also consider the problems of glare with LED lights by utilizing a diffuser to protect the eyes. We are assured of the potential advantages of LED lighting in the future.

  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. The effect of modern compact fluorescent lights on voltage distortion

    SciTech Connect

    Pileggi, D.J.; Gulachenski, E.M.; Root, C.E. ); Gentile, T.J. ); Emanuel, A.E. )

    1993-07-01

    This paper presents the results of a computer simulation of three real life 13.8kV feeders supplying consumers with non-linear loads which include CFL (Compact Fluorescent Lights) with electronic ballasts. The computer simulations are supported by laboratory testing and in-the-home installation/monitoring of CFL. The results of the laboratory tests and in-the-home monitoring were combined with load research information regarding residential load profiles to produce load models for use in computer simulation of the behavior of the three distribution feeders. The input current to electronically ballasted CFL has unusually high distortion, THD (total harmonic distortion) > 100%. The man conclusion of this work is that for a 15kV class feeder with a maximum 10 MVA load, the total load of electronically ballasted CFL should not exceed 100kW is the voltage THD is to be kept [<=] 5%.

  17. 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

  18. 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.

  19. 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.

  20. Neutral red as a specific light-up fluorescent probe for i-motif DNA.

    PubMed

    Xu, Lijun; Wang, Jine; Sun, Na; Liu, Min; Cao, Yi; Wang, Zhili; Pei, Renjun

    2016-12-06

    We report a specific light-up fluorescent probe for i-motif DNA for the first time. Compared with the previously reported probes, neutral red could selectively interact with an i-motif and show a significant increase in its fluorescence. This feature makes it advantageous for designing label-free fluorescent sensing systems.

  1. 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.

  2. 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

  3. Characteristics of Fluorescence and Delayed Light Emission from Green Photosynthetic Bacteria and Algae

    PubMed Central

    Clayton, Roderick K.

    1965-01-01

    Green photosynthetic bacteria exhibit variations in the intensity of their fluorescence during illumination. The initial intensity of fluorescence, measured at the onset of illumination, has a spectrum in which the major pigment Chlorobium chlorophyll predominates. The minor pigment bacteriochlorophyll predominates in the spectrum of the time-varying part of the fluorescence. The spectrum of delayed light emission is identical to that of the time-varying fluorescence. The variations in fluorescence also resemble the delayed light in their kinetics and in their dependence on exciting light intensity. Similar results are obtained for the kinetics of prompt and delayed light emission in the algae Chlorella and Anacystis. These findings raise the possibility that the variations in fluorescence actually represent a fast component of delayed light emission, of intensity comparable to the intensity of fluorescence. In Anacystis there is an outburst of light emission that develops after the exciting light has been turned off, reaching a maximum intensity after 1 to 3 seconds. This emitted light has the spectrum of chlorophyll fluorescence. It appears to be a novel example of bioluminescence with singlet excited chlorophyll as the emitter. PMID:14324979

  4. 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.

  5. 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

  6. Fluorescent light induces neurodegeneration in the rodent nigrostriatal system but near infrared LED light does not.

    PubMed

    Romeo, Stefania; Vitale, Flora; Viaggi, Cristina; di Marco, Stefano; Aloisi, Gabriella; Fasciani, Irene; Pardini, Carla; Pietrantoni, Ilaria; Di Paolo, Mattia; Riccitelli, Serena; Maccarone, Rita; Mattei, Claudia; Capannolo, Marta; Rossi, Mario; Capozzo, Annamaria; Corsini, Giovanni U; Scarnati, Eugenio; Lozzi, Luca; Vaglini, Francesca; Maggio, Roberto

    2017-03-02

    We investigated the effects of continuous artificial light exposure on the mouse substantia nigra (SN). A three month exposure of C57Bl/6J mice to white fluorescent light induced a 30% reduction in dopamine (DA) neurons in SN compared to controls, accompanied by a decrease of DA and its metabolites in the striatum. After six months of exposure, neurodegeneration progressed slightly, but the level of DA returned to the basal level, while the metabolites increased with respect to the control. Three month exposure to near infrared LED light (∼710 nm) did not alter DA neurons in SN, nor did it decrease DA and its metabolites in the striatum. Furthermore mesencephalic cell viability, as tested by [(3)H]DA uptake, did not change. Finally, we observed that 710 nm LED light, locally conveyed in the rat SN, could modulate the firing activity of extracellular-recorded DA neurons. These data suggest that light can be detrimental or beneficial to DA neurons in SN, depending on the source and wavelength.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Total light approach of time-domain fluorescence diffuse optical tomography.

    PubMed

    Marjono, Andhi; Yano, Akira; Okawa, Shinpei; Gao, Feng; Yamada, Yukio

    2008-09-15

    In this study, time-domain fluorescence diffuse optical tomography in biological tissue is numerically investigated using a total light approach. Total light is a summation of excitation light and zero-lifetime emission light divided by quantum yield. The zero-lifetime emission light is an emitted fluorescence light calculated by assuming that the fluorescence lifetime is zero. The zero-lifetime emission light is calculated by deconvolving the actually measured emission light with a lifetime function, an exponential function for fluorescence decay. The object for numerical simulation is a 2-D 10 mm-radius circle with the optical properties simulating biological tissues for near infrared light, and contains regions with fluorophore. The inverse problem of fluorescence diffuse optical tomography is solved using time-resolved simulated measurement data of the excitation and total lights for reconstructing the bsorption coefficient and fluorophore concentration simultaneously. The mean time of flight is used as the featured data-type extracted from the time-resolved data. The reconstructed images of fluorophore concentration show good quantitativeness and spatial reproducibility. By use of the total light approach, computation is performed much faster than the conventional ones.

  12. Revisiting the mechanism of nitrogen fluorescence emission induced by femtosecond filament in air

    NASA Astrophysics Data System (ADS)

    Li, Suyu; Jiang, Yuanfei; Chen, Anmin; He, Lanhai; Liu, Dunli; Jin, Mingxing

    2017-03-01

    The backward propagating and side emitted fluorescence during the femtosecond filamentation in air is experimentally investigated in this paper. By comparing the fluorescence emission in the circular and linear polarization states, we find that in the shorter focal length case, the direct ionization of N 2 greatly affects the fluorescence emission behaviors: the fluorescence from N2 + and N 2 is always stronger in the linear and circular polarization cases, respectively. Based on the observation, the emission mechanism of nitrogen fluorescence emission induced by a femtosecond filament is discussed.

  13. 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,"…

  14. 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.

  15. 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 ~\

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

    PubMed Central

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

    2013-01-01

    Abstract. 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. PMID:23584445

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Modulation of fluorescence signals from biomolecules along nanowires due to interaction of light with oriented nanostructures.

    PubMed

    Frederiksen, Rune S; Alarcon-Llado, Esther; Madsen, Morten H; Rostgaard, Katrine R; Krogstrup, Peter; Vosch, Tom; Nygård, Jesper; Fontcuberta I Morral, Anna; Martinez, Karen L

    2015-01-14

    High aspect ratio nanostructures have gained increasing interest as highly sensitive platforms for biosensing. Here, well-defined biofunctionalized vertical indium arsenide nanowires are used to map the interaction of light with nanowires depending on their orientation and the excitation wavelength. We show how nanowires act as antennas modifying the light distribution and the emitted fluorescence. This work highlights an important optical phenomenon in quantitative fluorescence studies and constitutes an important step for future studies using such nanostructures.

  2. 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).

  3. White light-emitting diode with quasisolar spectrum based on organic fluorescent dyes

    NASA Astrophysics Data System (ADS)

    Chung, Shuang-Chao; Li, Ming-Chia; Sun, Ching-Cherng

    2015-07-01

    We present a study of light-emitting diodes (LEDs) using organic fluorescent dyes to replace the general phosphor. The blue die with a specific organic fluorescent dye gives the LED a single color appearance. Through a color-mixing cavity, multiple LEDs are used to produce a quasisolar spectrum at a certain band and white light with a color rendering index as high as 97 at around 2800 K.

  4. Vibrio azureus emits blue-shifted light via an accessory blue fluorescent protein.

    PubMed

    Yoshizawa, Susumu; Karatani, Hajime; Wada, Minoru; Kogure, Kazuhiro

    2012-04-01

    Luminous marine bacteria usually emit bluish-green light with a peak emission wavelength (λ(max) ) at about 490 nm. Some species belonging to the genus Photobacterium are exceptions, producing an accessory blue fluorescent protein (lumazine protein: LumP) that causes a blue shift, from λ(max)  ≈ 490 to λ(max)  ≈ 476 nm. However, the incidence of blue-shifted light emission or the presence of accessory fluorescent proteins in bacteria of the genus Vibrio has never been reported. From our spectral analysis of light emitted by 16 luminous strains of the genus Vibrio, it was revealed that most strains of Vibrio azureus emit a blue-shifted light with a peak at approximately 472 nm, whereas other Vibrio strains emit light with a peak at around 482 nm. Therefore, we investigated the mechanism underlying this blue shift in V. azureus NBRC 104587(T) . Here, we describe the blue-shifted light emission spectra and the isolation of a blue fluorescent protein. Intracellular protein analyses showed that this strain had a blue fluorescent protein (that we termed VA-BFP), the fluorescent spectrum of which was almost identical to that of the in vivo light emission spectrum of the strain. This result strongly suggested that VA-BFP was responsible for the blue-shifted light emission of V. azureus.

  5. Stopping light by an air waveguide with anisotropic metamaterial cladding.

    PubMed

    Jiang, Tian; Zhao, Junming; Feng, Yijun

    2009-01-05

    We present a detailed study of oscillating modes in a slab waveguide with air core and anisotropic metamaterial cladding. It is shown that, under specific dielectric configurations, slow and even stopped electromagnetic wave can be supported by such an air waveguide. We propose a linearly tapped waveguide structure that could lead the propagating light to a complete standstill. Both the theoretical analysis and the proposed waveguide have been validated by full-wave simulation based on finite-difference time-domain method.

  6. On the advantages of using green light to study fluorescence yield changes in leaves.

    PubMed

    Rappaport, Fabrice; Béal, Daniel; Joliot, Anne; Joliot, Pierre

    2007-01-01

    In photosynthetic chains, the kinetics of fluorescence yield depends on the photochemical rates at the level of both Photosystem I and II and thus on the absorption cross section of the photosynthetic units as well as on the coupling between light harvesting complexes and photosynthetic traps. A new set-up is described which, at variance with the commonly used set-ups, uses of a weakly absorbed light source (light-emitting diodes with maximum output at 520 nm) to excite the photosynthetic electron chain and probe the resulting fluorescence yield changes and their time course. This approach optimizes the homogeneity of the exciting light throughout the leaf and we show that this homogeneity narrows the distribution of the photochemical rates. Although the exciting light is weakly absorbed, the possibility to tune the intensity of the light emitting diodes allows one to reach photochemical rates ranging from 10(4) s(-1) to 0.25 s(-1) rendering experimentally accessible different functional regimes. The variations of the fluorescence yield induced by the photosynthetic activity are qualitatively and quantitatively discussed. When illuminating dark-adapted leaves by a weak light, the kinetics of fluorescence changes displays a pronounced plateau which precedes the fluorescence increase reflecting the full reduction of the plastoquinone pool. We ascribe this plateau to the time delay needed to reduce the photosystem I electron acceptors.

  7. 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

  8. UV/blue light-induced fluorescence for assessing apple maturity

    NASA Astrophysics Data System (ADS)

    Noh, Hyun Kwon; Lu, Renfu

    2005-11-01

    Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples by using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

  9. Red fluorescence of the triplefin Tripterygion delaisi is increasingly visible against background light with increasing depth

    PubMed Central

    Harant, Ulrike K.; Fritsch, Roland; Michiels, Nico K.

    2017-01-01

    The light environment in water bodies changes with depth due to the absorption of short and long wavelengths. Below 10 m depth, red wavelengths are almost completely absent rendering any red-reflecting animal dark and achromatic. However, fluorescence may produce red coloration even when red light is not available for reflection. A large number of marine taxa including over 270 fish species are known to produce red fluorescence, yet it is unclear under which natural light environment fluorescence contributes perceptively to their colours. To address this question we: (i) characterized the visual system of Tripterygion delaisi, which possesses fluorescent irides, (ii) separated the colour of the irides into its reflectance and fluorescence components and (iii) combined these data with field measurements of the ambient light environment to calculate depth-dependent perceptual chromatic and achromatic contrasts using visual modelling. We found that triplefins have cones with at least three different spectral sensitivities, including differences between the two members of the double cones, giving them the potential for trichromatic colour vision. We also show that fluorescence contributes increasingly to the radiance of the irides with increasing depth. Our results support the potential functionality of red fluorescence, including communicative roles such as species and sex identity, and non-communicative roles such as camouflage.

  10. 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.

  11. 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.

  12. 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.

  13. Fluorescence enhancement and reflection of the excitation light observed with a multilayered substrate.

    PubMed

    Akimoto, Takuo; Yasuda, Mitsuru

    2010-01-01

    Fluorescence enhancement from a multilayered substrate fabricated with Ag and Al(2)O(3) was investigated using fluorescein, rhodamine B, Cy3, and Cy5 as fluorophores. The change in the fluorescence enhancement with Al(2)O(3) had two peaks and one valley in the range from 0 to 300 nm of Al(2)O(3) thickness, and such peaks and valley were found to appear periodically. Moreover, the reflection of the excitation light from the multilayered substrate was investigated. The reflection of the excitation light periodically changed depending on the Al(2)O(3) thickness as well, and the maximum reflection was observed near the Al(2)O(3) thickness of the peak fluorescence enhancement. It was found that the periodic changes of the fluorescence enhancement and the reflection of the excitation light could be explained, for the most part, with the integral multiples of the lambda/4 derived by a simple interference theory.

  14. 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.

  15. Highly bright broadband red light produced by fluorescence polymer/InGaN hybrid light-emitting diodes.

    PubMed

    Lai, Chun-Feng; Chang, Chi-Jung; Hsieh, Cheng-Liang; Chen, Yung-Lin; Tuan, Chi-Shen

    2013-10-15

    The fabrication of fluorescence polymer/InGaN hybrid light-emitting diodes (LEDs) that emit highly bright broadband red light is presented in this Letter. The absorption peak of the fluorescence polymer was 455 nm, and the emission peak was 640 nm. The light output power and external quantum efficiency of hybrid LEDs at a driving current of 100 mA were 46.6 mW and 24.1%, respectively. The emission spectrum of hybrid LEDs was located at a wavelength of 641 nm, with a broadband FWHM of 106 nm. Thus this study offers potential methods for enhancing the output power of commercial white-light-emitting devices.

  16. [Effect of Methylmercury on the Light Dependence Fluorescence Parameters in a Green Alga Chlamydomonas moewusii].

    PubMed

    Protopopov, F F; Matorin, D N; Seifullina, N H; Bratkovskaya, L B; Zayadan, B K

    2015-01-01

    The effect of a dangerous toxic substance, methylmercury, on light dependence curves of chlorophyll fluorescence in Chlamydomonas moewusii was studied. We found low concentration of methylmercury (10(-7) M) to cause a decrease in the relative rate of the non-cyclic electron transport activity of PS 2, a decline in the maximum utilization of light energy (α), and a decline in the saturation light intensity (E(s)). Non-photochemical fluorescence quenching increased after short-term exposure and decreased in the course of prolonged incubation. These parameters were more sensitive to the action of the toxic substance than the widely used parameter F(V)/F(M), which reflects the maximum quantum yield of PS 2. We propose the use of the method of fast measurement of light dependence curves of fluorescence to detect the changes in algal cells at the early stages of exposure to mercury salts.

  17. Variability in chlorophyll fluorescence spectra of eggplant fruit grown under different light environments: a case study.

    PubMed

    Ospina Calvo, Brian; Parapugna, Tamara L; Lagorio, M Gabriela

    2017-03-13

    The main goal of the present work was to clarify physiological strategies in plants whose chloroplasts were developed under different light environments. The specific objective was to elucidate the influence of the spectral distribution of light on the chlorophyll fluorescence ratio and on photosynthetic parameters. To achieve this purpose, three species of eggplant fruit (black, purple and white striped and white) were used as a case study and their chlorophyll fluorescence was analyzed in detail. Spectra of the non-variable fluorescence in each part of the fruit were corrected for distortions by light reabsorption processes using a physical model. The main conclusion of this work was that the corrected fluorescence ratio was dependent on the contribution of each photosystem to the fluorescence and consequently on the environmental lighting conditions, becoming higher when illumination was rich in long wavelengths. Variable chlorophyll fluorescence, similar to that observed from plant leaves, was detected for the pulp of the black eggplant, for the pulp of the purple and white striped eggplant and for the intact fruit of the black eggplant. The maximum quantum efficiency of photosystem II in the light-adapted state (F'v/F'm), the quantum efficiency of photosystem II (ΦPSII), and the photochemical and non-photochemical quenching coefficients (qP and qNP/NPQ respectively) were determined in each case. The results could be explained very interestingly, in relation with the proportion of exciting light reaching each photosystem (I and II). The photochemical parameters obtained from variable chlorophyll fluorescence, allowed us to monitor non-destructively the physiological state of the black fruit during storage under both chilled or room-temperature conditions.

  18. 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.

  19. 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.

  20. Total-reflection X-ray fluorescence — a tool to obtain information about different air masses and air pollution

    NASA Astrophysics Data System (ADS)

    Schmeling, Martina

    2001-11-01

    Atmospheric aerosols are solid particles dissolved in air and change their chemical composition frequently depending on various parameters. In order to identify regional air circulation atmospheric aerosol filter samples were taken at Loyola University Chicago's Lake Shore Campus during the months of July and August 2000 with sampling times ranging between 1 and 2 h. The samples were digested in a microwave oven and analyzed by total-reflection X-ray fluorescence (TXRF) spectrometry. One diurnal variation comprising five consecutive sampling events was selected and discussed as well as 4 days experiencing different meteorology were compared to exemplify the variation in trace elemental concentration according to air mass movements and highlight the capability of total-reflection X-ray fluorescence analysis. It was found that due to changes in meteorological conditions particularly wind direction and wind speed, trace elemental compositions varied rapidly and could be used to distinguish between 'Lake Michigan air' and 'metropolitan Chicago air' on such short-term time scale like one hour. Back trajectory analysis was applied to support and corroborate the results. The outcome of this study clearly shows that total-reflection X-ray fluorescence is an optimal tool for analysis of atmospheric aerosols.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  2. 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

  3. Light propagation and fluorescence quantum yields in liquid scintillators

    NASA Astrophysics Data System (ADS)

    Buck, C.; Gramlich, B.; Wagner, S.

    2015-09-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  4. 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.

  5. A visible-light-excited fluorescence method for imaging protein crystals without added dyes.

    PubMed

    Lukk, Tiit; Gillilan, Richard E; Szebenyi, Doletha M E; Zipfel, Warren R

    2016-02-01

    Fluorescence microscopy methods have seen an increase in popularity in recent years for detecting protein crystals in screening trays. The fluorescence-based crystal detection methods have thus far relied on intrinsic UV-inducible tryptophan fluorescence, nonlinear optics or fluorescence in the visible light range dependent on crystals soaked with fluorescent dyes. In this paper data are presented on a novel visible-light-inducible autofluorescence arising from protein crystals as a result of general stabilization of conjugated double-bond systems and increased charge delocalization due to crystal packing. The visible-light-inducible autofluorescence serves as a complementary method to bright-field microscopy in beamline applications where accurate crystal centering about the rotation axis is essential. Owing to temperature-dependent chromophore stabilization, protein crystals exhibit tenfold higher fluorescence intensity at cryogenic temperatures, making the method ideal for experiments where crystals are cooled to 100 K with a cryostream. In addition to the non-damaging excitation wavelength and low laser power required for imaging, the method can also serve a useful role for differentiating protein crystals from salt crystals in screening trays.

  6. Metal-enhanced fluorescence of chlorophylls in light-harvesting complexes coupled to silver nanowires.

    PubMed

    Kowalska, Dorota; Krajnik, Bartosz; Olejnik, Maria; Twardowska, Magdalena; Czechowski, Nikodem; Hofmann, Eckhard; Mackowski, Sebastian

    2013-01-01

    We investigate metal-enhanced fluorescence of peridinin-chlorophyll protein coupled to silver nanowires using optical microscopy combined with spectrally and time-resolved fluorescence techniques. In particular we study two different sample geometries: first, in which the light-harvesting complexes are deposited onto silver nanowires, and second, where solution of both nanostructures are mixed prior deposition on a substrate. The results indicate that for the peridinin-chlorophyll complexes placed in the vicinity of the silver nanowires we observe higher intensities of fluorescence emission as compared to the reference sample, where no nanowires are present. Enhancement factors estimated for the sample where the light-harvesting complexes are mixed together with the silver nanowires prior deposition on a substrate are generally larger in comparison to the other geometry of a hybrid nanostructure. While fluorescence spectra are identical both in terms of overall shape and maximum wavelength for peridinin-chlorophyll-protein complexes both isolated and coupled to metallic nanostructures, we conclude that interaction with plasmon excitations in the latter remains neutral to the functionality of the biological system. Fluorescence transients measured for the PCP complexes coupled to the silver nanowires indicate shortening of the fluorescence lifetime pointing towards modifications of radiative rate due to plasmonic interactions. Our results can be applied for developing ways to plasmonically control the light-harvesting capability of photosynthetic complexes.

  7. A visible-light-excited fluorescence method for imaging protein crystals without added dyes

    PubMed Central

    Lukk, Tiit; Gillilan, Richard E.; Szebenyi, Doletha M. E.; Zipfel, Warren R.

    2016-01-01

    Fluorescence microscopy methods have seen an increase in popularity in recent years for detecting protein crystals in screening trays. The fluorescence-based crystal detection methods have thus far relied on intrinsic UV-inducible tryptophan fluorescence, nonlinear optics or fluorescence in the visible light range dependent on crystals soaked with fluorescent dyes. In this paper data are presented on a novel visible-light-inducible autofluorescence arising from protein crystals as a result of general stabilization of conjugated double-bond systems and increased charge delocalization due to crystal packing. The visible-light-inducible autofluorescence serves as a complementary method to bright-field microscopy in beamline applications where accurate crystal centering about the rotation axis is essential. Owing to temperature-dependent chromophore stabilization, protein crystals exhibit tenfold higher fluorescence intensity at cryogenic temperatures, making the method ideal for experiments where crystals are cooled to 100 K with a cryostream. In addition to the non-damaging excitation wavelength and low laser power required for imaging, the method can also serve a useful role for differentiating protein crystals from salt crystals in screening trays. PMID:26937240

  8. 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.

  9. Quantitative in vivo imaging of entire embryos with Digital Scanned Laser Light Sheet Fluorescence Microscopy.

    PubMed

    Keller, Philipp J; Stelzer, Ernst H K

    2008-12-01

    The observation of biological processes in their natural in vivo context is a key requirement for quantitative experimental studies in the life sciences. In many instances, it will be crucial to achieve high temporal and spatial resolution over long periods of time without compromising the physiological development of the specimen. Here, we discuss the principles underlying light sheet-based fluorescence microscopes. The most recent implementation DSLM is a tool optimized to deliver quantitative data for entire embryos at high spatio-temporal resolution. We compare DSLM to the two established light microscopy techniques: confocal and two-photon fluorescence microscopy. DSLM provides up to 50 times higher imaging speeds and a 10-100 times higher signal-to-noise ratio, while exposing the specimens to at least three orders of magnitude less light energy than confocal and two-photon fluorescence microscopes. We conclude with a perspective for future development.

  10. 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.

  11. 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.

  12. 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.

  13. Molecular basis of the light-driven switching of the photochromic fluorescent protein Padron.

    PubMed

    Brakemann, Tanja; Weber, Gert; Andresen, Martin; Groenhof, Gerrit; Stiel, Andre C; Trowitzsch, Simon; Eggeling, Christian; Grubmüller, Helmut; Hell, Stefan W; Wahl, Markus C; Jakobs, Stefan

    2010-05-07

    Reversibly switchable fluorescent proteins can be repeatedly photoswitched between a fluorescent and a nonfluorescent state by irradiation with the light of two different wavelengths. The molecular basis of the switching process remains a controversial topic. Padron0.9 is a reversibly switchable fluorescent protein with "positive" switching characteristics, exhibiting excellent spectroscopic properties. Its chromophore is formed by the amino acids Cys-Tyr-Gly. We obtained high resolution x-ray structures of Padron0.9 in both the fluorescent and the nonfluorescent states and used the structural information for molecular dynamics simulations. We found that in Padron0.9 the chromophore undergoes a cis-trans isomerization upon photoswitching. The molecular dynamics simulations clarified the protonation states of the amino acid residues within the chromophore pocket that influence the protonation state of the chromophore. We conclude that a light driven cis-trans isomerization of the chromophore appears to be the fundamental switching mechanism in all photochromic fluorescent proteins known to date. Distinct absorption cross-sections for the switching wavelengths in the fluorescent and the nonfluorescent state are not essential for efficient photochromism in fluorescent proteins, although they may facilitate the switching process.

  14. 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.

  15. Combination of normal light and fluorescence microscopy for authentication of five Lonicera species flower buds.

    PubMed

    Chu, Chu; Liu, Hui-Juan; Qi, Lian-Wen; Liu, E-Hu; Li, Ping

    2011-02-01

    The flower buds of five Lonicera species, Lonicera japonica Thunb., L. macranthoides Hand.-Mazz., L. hypoglauca Miq., L. confusa DC. and L. fulvotomentosa Hsu et S.C. Cheng are confusable and usually utilized under the same name "Jinyinhua" in different areas for morphological similarity. Studies found that these five species possess extreme differences in chemical compounds, correspondingly showing different pharmacological activities and clinical applications. To ensure efficacy and safety of these herbal medicines and prevent unknown adverse effect, in this work, a simple, rapid and effective method combining normal light and fluorescence microscopy was developed for authentication. Surface slides and transverse sections of these buds were investigated to reveal their differences. As a routine technique, normal light microscopy which gives detailed microscopic features such as glandular hairs and nonglandular hairs, can easily distinguish four species except L. confusa. Fluorescence technique, which could present different distribution of fluorescence materials, is further employed to identify three species including L. confusa successfully. It is the first report to identify these five Lonicera species by combining normal light and fluorescence microscopy. This work indicated combining normal light and fluorescence microscopy could be a powerful method in authentication of confused species.

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

    DOEpatents

    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.

  17. Enhancing Air Power’s Contribution Against Light Infantry Targets

    DTIC Science & Technology

    1996-01-01

    Imagery Interpretability Rating Scale OPCON Operational concept PSSM Precision Standoff Support Munition PtSi Platinum silicide RCS Radar cross...example, the coordinates could be passed to an air- craft armed with a RAND-proposed weapon, the Precision Standoff Support Munition ( PSSM ).15 Designed...to provide quick-response heavy-fire support to U.S. light infantry, the PSSM is an 8-in. artillery shell modified with fins and a GPS guidance

  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 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

  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

    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.

  20. Chemical nature of the light emitter of the Aequorea green fluorescent protein.

    PubMed

    Niwa, H; Inouye, S; Hirano, T; Matsuno, T; Kojima, S; Kubota, M; Ohashi, M; Tsuji, F I

    1996-11-26

    The jellyfish Aequorea victoria possesses in the margin of its umbrella a green fluorescent protein (GFP, 27 kDa) that serves as the ultimate light emitter in the bioluminescence reaction of the animal. The protein is made up of 238 amino acid residues in a single polypeptide chain and produces a greenish fluorescence (lambda max = 508 nm) when irradiated with long ultraviolet light. The fluorescence is due to the presence of a chromophore consisting of an imidazolone ring, formed by a post-translational modification of the tripeptide -Ser65-Tyr66-Gly67-. GFP has been used extensively as a reporter protein for monitoring gene expression in eukaryotic and prokaryotic cells, but relatively little is known about the chemical mechanism by which fluorescence is produced. To obtain a better understanding of this problem, we studied a peptide fragment of GFP bearing the chromophore and a synthetic model compound of the chromophore. The results indicate that the GFP chromophore consists of an imidazolone ring structure and that the light emitter is the singlet excited state of the phenolate anion of the chromophore. Further, the light emission is highly dependent on the microenvironment around the chromophore and that inhibition of isomerization of the exo-methylene double bond of the chromophore accounts for its efficient light emission.

  1. In situ response of phytoplankton fluorescence to rapid variations in light

    SciTech Connect

    Abbott, M.R.; Richerson, P.J.; Powell, T.M.

    1982-03-01

    Phytoplankton chlorophyll a fluorescence responded to rapid fluctuations in light intensity in Lake Tahoe at three depths: 10, 35, and 60 m. Fluroescence yield was negatively correlated with surface irradiance at all depths, but there was a strong depth dependence in the intensity of this response. Phytoplankton at 35 m reacted more strongly to fluctuations than those at 10 or 60 m and therefore could show a noticeable response to more rapid variations. This may have been due to near-optimal light levels at 35 m, light inhibition at 10, and light limitation at 60 m.

  2. Mechanistic studies of the genetically encoded fluorescent protein voltage probe ArcLight.

    PubMed

    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.

  3. 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.

  4. Light use efficiency of terrestrial vegetation from remote sensing of chlorophyll fluorescence

    NASA Astrophysics Data System (ADS)

    Badgley, G. M.; Guan, K.; Berry, J. A.; Lobell, D. B.; Ryu, Y.

    2014-12-01

    Light use efficiency, the rate with which plants use absorbed photons to fix carbon dioxide, is a crucial parameter for estimating terrestrial carbon fluxes. Estimates of light use efficiency lie at the heart of how we model and understand ecosystem productivity. Here, we make use of the recent availability of high-resolution, multi-year records of remotely sensed measurements of chlorophyll fluorescence to refine estimates of light use efficiency in terrestrial ecosystems at the global scale. Directly estimating light use efficiency from remote sensing can help guide the current approach of constraining a theoretical maximum light use efficiency using meteorological data. We explore the usefulness of a derived light use efficiency at the global scale from remotely sensed records of chlorophyll fluorescence, photosynthetically active radiation, and canopy leaf area. Our estimates of light use efficiency show good agreement with light use efficiency calculated using Fluxtower data spanning several continents and a wide variety of ecosystems. We further benchmark our approach against the light use efficiency estimated from a variety of ecosystem models, such as BESS. Further refinement of our proposed technique promises to advance our ability to detect ecosystem stresses and further constrain our estimates of carbon fluxes within terrestrial ecosystems.

  5. 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.

  6. Highly linearly polarized white light emission from InGaN light-emitting diode with nanograting-integrated fluorescent ceramics

    NASA Astrophysics Data System (ADS)

    Chen, Linghua; Wang, Miao; Cao, Bing; Zhou, Shengming; Lin, Yu; Hu, Jingpei; Wang, Chinhua; Wang, Jianfeng; Sun, Qian; Xu, Ke

    2017-01-01

    We proposed and demonstrated a linearly polarized white light emission from an InGaN light-emitting diode with nanograting-integrated fluorescent ceramics. By incorporating a dielectric layer with low refractive index between multilayer nanogratings and a fluorescent ceramic, both high TM transmission (TMT) and high extinction ratio (ER) were effectively achieved across the entire range of white light. An ER higher than 20 dB and a TMT of 60% were obtained experimentally for a GaN/fluorescent-ceramic-integrated white LED with a multilayer grating of 150 nm period. The fluorescent-ceramic-integrated structure showed possibilities of implementing a polarized white LED with high performance.

  7. A model considering light reabsorption processes to correct in vivo chlorophyll fluorescence spectra in apples.

    PubMed

    Ramos, María E; Lagorio, María G

    2006-05-01

    Chlorophyll-a contained in the peel of Granny Smith apples emits fluorescence upon excitation with blue light. The observed emission, collected by an external detector and corrected by its spectral response, is still distorted by light reabsorption processes taking place in the fruit skin and differs appreciably from the true spectral distribution of fluorescence emerging from chlorophyll molecules in the biological tissue. Reabsorption processes particularly affect the ratio of fluorescence intensities at 680 nm and at 730 nm. A model to obtain the correct spectral distribution of the emission, from the experimental fluorescence recorded at a fluorometer detector and corrected for the detector spectral sensitivity, is developed in the present work. Measurements of the whole fruit reflectance, the peel transmittance and the flesh reflectance allow the calculation of the reabsorption-corrected spectra. The model is validated by comparing the corrected emission spectra with that obtained for a thin layer of apple-peel-chloroplasts, where no reabsorption takes place. It is recommended to correct distortions in emission spectra of intact fruits due to light reabsorption effects whenever a correlation between the physiological state of the fruit and its fluorescence spectra is investigated.

  8. Kerosene lighting contributes to household air pollution in rural Uganda.

    PubMed

    Muyanja, D; Allen, J G; Vallarino, J; Valeri, L; Kakuhikire, B; Bangsberg, D R; Christiani, D C; Tsai, A C; Lai, P S

    2017-03-07

    The literature on the contribution of kerosene lighting to indoor air particulate concentrations is sparse. In rural Uganda, kitchens are almost universally located outside the main home, and kerosene is often used for lighting. In this study, we obtained longitudinal measures of particulate matter 2.5 microns or smaller in size (PM2.5 ) from living rooms and kitchens of 88 households in rural Uganda. Linear mixed effects models with a random intercept for household were used to test the hypotheses that primary reported lighting source and kitchen location (indoor vs. outdoor) is associated with PM2.5 levels. During initial testing, households reported using the following sources of lighting: open wick kerosene (19.3%), hurricane kerosene (45.5%), battery powered (33.0%), and solar (1.1%) lamps. During follow-up testing these proportions changed to 29.5%, 35.2%, 18.2%, and 9.1%, respectively. Average ambient, living room, and kitchen PM2.5 levels were 20.2, 35.2, and 270.0 μg/m(3) . Living rooms using open wick kerosene lamps had the highest PM2.5 levels (55.3 μg/m(3) ) compared to those using solar lighting (19.4 μg/m(3) ; open wick vs. solar, p = 0.01). 27.6% of homes using open wick kerosene lamps met World Health Organization indoor air quality standards compared to 75.0% in homes using solar lighting. This article is protected by copyright. All rights reserved.

  9. Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light

    PubMed Central

    Wang, Ying Min; Judkewitz, Benjamin; DiMarzio, Charles A.; Yang, Changhuei

    2012-01-01

    Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×105). We confirm the presence of a time-reversed optical focus along with a diffuse background—a corollary of partial phase conjugation—and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 μm×52 μm and an axial resolution of 657 μm. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics. PMID:22735456

  10. Live imaging of Tribolium castaneum embryonic development using light-sheet-based fluorescence microscopy.

    PubMed

    Strobl, Frederic; Schmitz, Alexander; Stelzer, Ernst H K

    2015-10-01

    Tribolium castaneum has become an important insect model organism for evolutionary developmental biology, genetics and biotechnology. However, few protocols for live fluorescence imaging of Tribolium have been reported, and little image data is available. Here we provide a protocol for recording the development of Tribolium embryos with light-sheet-based fluorescence microscopy. The protocol can be completed in 4-7 d and provides procedural details for: embryo collection, microscope configuration, embryo preparation and mounting, noninvasive live imaging for up to 120 h along multiple directions, retrieval of the live embryo once imaging is completed, and image data processing, for which exemplary data is provided. Stringent quality control criteria for developmental biology studies are also discussed. Light-sheet-based fluorescence microscopy complements existing toolkits used to study Tribolium development, can be adapted to other insect species, and requires no advanced imaging or sample preparation skills.

  11. 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.

  12. 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.

  13. Measuring Light Air Ions in a Speleotherapeutic Cave

    NASA Astrophysics Data System (ADS)

    Roubal, Z.; Bartušek, K.; Szabó, Z.; Drexler, P.; Überhuberová, J.

    2017-02-01

    The paper deals with a methodology proposed for measuring the concentration of air ions in the environment of speleotherapeutic caves, and with the implementation of the AK-UTEE-v2 ionmeter. Speleotherapy, in the context of its general definition, is the medical therapy that utilizes the climate of selected caves to treat patients with health problems such as asthma. These spaces are characterized by the presence of high air humidity and they make extreme demands on the execution of the measuring device, the Gerdien tube (GT in the following) in particular, and on the amplifier electronics. The result is an automated measuring system using a GT with low-volume air flow, enabling long-term measuring of air ion concentration and determination of spectral ion characteristics. Interesting from the instrumentation viewpoint are the GT design, active shielding, and execution of the electrometric amplifier. A specific method for the calculation of spectral ion characteristics and the mode of automatic calibration were proposed and a procedure of automatic measurement in the absence of attendants was set up. The measuring system is designed for studying and long-term monitoring of the concentration of light negative ions in dependence on climatic conditions and on the mobility of ions occurring in the cave.

  14. Self-assembled fluorescent hexaazatriphenylenes that act as a light-harvesting antenna.

    PubMed

    Ishi-i, Tsutomu; Murakami, Koh-ichi; Imai, Yusuke; Mataka, Shuntaro

    2006-07-21

    In this paper we report the self-assembling nature of fluorescent hexaazatriphenylenes (HATs) 6a-d with six alkyl/alkoxy-chain-containing biphenyl groups and their application to light-harvesting antennae. In a nonpolar solvent and the film state, the HAT derivatives form one-dimensional aggregates with an H-type parallel stacking mode, which were analyzed by 1H NMR, UV-vis, and steady-state and time-resolved fluorescence spectroscopy. When HAT derivative 7 with six perylenediimide moieties is incorporated into the one-dimensional aggregates, an efficient energy transfer takes place from the self-assembled HAT moiety as a light-harvesting antenna to the perylenediimide moiety as an energy acceptor. Further, when HAT derivative 8 with six triphenylamino moieties is newly added to the light-harvesting system, an intermolecular electron transfer occurs subsequently between the electron-accepting perylenediimide molecule and the electron-donating triphenylamino molecule.

  15. 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.

  16. 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.

  17. High-power, computer-controlled, light-emitting diode-based light sources for fluorescence imaging and image-guided surgery.

    PubMed

    Gioux, Sylvain; Kianzad, Vida; Ciocan, Razvan; Gupta, Sunil; Oketokoun, Rafiou; Frangioni, John V

    2009-01-01

    Optical imaging requires appropriate light sources. For image-guided surgery, in particular fluorescence-guided surgery, a high fluence rate, a long working distance, computer control, and precise control of wavelength are required. In this article, we describe the development of light-emitting diode (LED)-based light sources that meet these criteria. These light sources are enabled by a compact LED module that includes an integrated linear driver, heat dissipation technology, and real-time temperature monitoring. Measuring only 27 mm wide by 29 mm high and weighing only 14.7 g, each module provides up to 6,500 lx of white (400-650 nm) light and up to 157 mW of filtered fluorescence excitation light while maintaining an operating temperature < or = 50 degrees C. We also describe software that can be used to design multimodule light housings and an embedded processor that permits computer control and temperature monitoring. With these tools, we constructed a 76-module, sterilizable, three-wavelength surgical light source capable of providing up to 40,000 lx of white light, 4.0 mW/cm2 of 670 nm near-infrared (NIR) fluorescence excitation light, and 14.0 mW/cm2 of 760 nm NIR fluorescence excitation light over a 15 cm diameter field of view. Using this light source, we demonstrated NIR fluorescence-guided surgery in a large-animal model.

  18. 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.

  19. 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.

  20. Optical fiber light-emitting diode-induced fluorescence detection for capillary electrophoresis.

    PubMed

    Zhao, Shulin; Yuan, Hongyan; Xiao, Dan

    2006-02-01

    A highly sensitive optical fiber light-emitting diode (LED)-induced fluorescence detector for CE has been constructed and evaluated. In this detector, a violet or blue LED was used as the excitation source and an optical fiber with 40 microm OD was used to transmit the excitation light. The upper end of the fiber was inserted into the separation capillary and was situated right at the detection window. Fluorescence emission was collected by a 40 x microscope objective, focused on a spatial filter, and passed through a cutoff filter before reaching the photomultiplier tube. Output signals were recorded and processed with a computer using in-house written software. The present CE/fluorescence detector deploys a simple and inexpensive optical system that requires only an LED as the light source. Its utility was successfully demonstrated by the separation and determination of amino acids (AAs) labeled with naphthalene-2,3-dicarboxaldehyde (NDA) and FITC. Low detection limits were obtained ranging from 17 to 23 nM for NDA-tagged AAs and 8 to 12 nM for FITC-labeled AAs (S/N=3). By virtue of such valuable features as low cost, convenience, and miniaturization, the presented detection scheme was proven to be attractive for sensitive fluorescence detection in CE.

  1. 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

  2. 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.

  3. Fluorescence in scorpions under UV light; can chaerilids be a possible exception?

    PubMed

    Lourenço, Wilson R

    2012-12-01

    The fluorescence of scorpions in ultraviolet light, a well-known phenomenon, was discovered more than 60 years ago. Its possible function remains, however, a matter of discussion. Even during very recent studies, no conclusion has been reached. As suggested in these recent publications, the lack of or reduction of fluorescence could be a useful tool to explain the phenomenon. It is suggested here that, in at least some species of the family Chaerilidae Simon, this phenomenon is absent. This new discovery may initiate important comparative eco-physiological studies.

  4. 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.

  5. 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.

  6. High Power, Computer-Controlled, LED-Based Light Sources for Fluorescence Imaging and Image-Guided Surgery

    PubMed Central

    Gioux, Sylvain; Kianzad, Vida; Ciocan, Razvan; Gupta, Sunil; Oketokoun, Rafiou; Frangioni, John V.

    2009-01-01

    Optical imaging requires appropriate light sources. For image-guided surgery, and in particular fluorescence-guided surgery, high fluence rate, long working distance, computer control, and precise control of wavelength are required. In this study, we describe the development of light emitting diode (LED)-based light sources that meet these criteria. These light sources are enabled by a compact LED module that includes an integrated linear driver, heat-dissipation technology, and real-time temperature monitoring. Measuring only 27 mm W by 29 mm H, and weighing only 14.7 g, each module provides up to 6500 lx of white (400-650 nm) light and up to 157 mW of filtered fluorescence excitation light, while maintaining an operating temperature ≤ 50°C. We also describe software that can be used to design multi-module light housings, and an embedded processor that permits computer control and temperature monitoring. With these tools, we constructed a 76-module, sterilizable, 3-wavelength surgical light source capable of providing up to 40,000 lx of white light, 4.0 mW/cm2 of 670 nm near-infrared (NIR) fluorescence excitation light, and 14.0 mW/cm2 of 760 nm NIR fluorescence excitation light over a 15-cm diameter field-of-view. Using this light source, we demonstrate NIR fluorescence-guided surgery in a large animal model. PMID:19723473

  7. 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

  8. Direct Evidence of Lack of Colocalisation of Fluorescently Labelled Gold Labels Used in Correlative Light Electron Microscopy

    PubMed Central

    Miles, Benjamin T.; Greenwood, Alexander B.; Benito-Alifonso, David; Tanner, Hugh; Galan, M. Carmen; Verkade, Paul; Gersen, Henkjan

    2017-01-01

    Fluorescently labelled nanoparticles are routinely used in Correlative Light Electron Microscopy (CLEM) to combine the capabilities of two separate microscope platforms: fluorescent light microscopy (LM) and electron microscopy (EM). The inherent assumption is that the fluorescent label observed under LM colocalises well with the electron dense nanoparticle observed in EM. Herein we show, by combining single molecule fluorescent imaging with optical detection of the scattering from single gold nanoparticles, that for a commercially produced sample of 10 nm gold nanoparticles tagged to Alexa-633 there is in fact no colocalisation between the fluorescent signatures of Alexa-633 and the scattering associated with the gold nanoparticle. This shows that the attached gold nanoparticle quenches the fluorescent signal by ~95%, or less likely that the complex has dissociated. In either scenario, the observed fluorescent signal in fact arises from a large population of untagged fluorophores; rendering these labels potentially ineffective and misleading to the field. PMID:28317888

  9. Air fluorescence efficiency measurements for AIRWATCH based mission: Experimental set-up

    SciTech Connect

    Biondo, B.; Catalano, O.; Celi, F.; Fazio, G.; Giarrusso, S.; La Rosa, G.; Mangano, A.; Bonanno, G.; Cosentino, R.; Di Benedetto, R.; Scuderi, S.; Richiusa, G.; Gregorio, A.

    1998-06-15

    In the framework of the AIRWATCH project we present an experimental set-up to measure the efficiency of the UV fluorescence production of the air using hard X-ray stimulus. The measures will be carried out at different pressure and temperature to emulate the same condition of the upper layers of the atmosphere where X-ray and gamma ray photons of Gamma Ray Bursts are absorbed.

  10. 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.

  11. 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.

  12. Light-sheet fluorescence imaging to localize cardiac lineage and protein distribution

    PubMed Central

    Ding, Yichen; Lee, Juhyun; Ma, Jianguo; Sung, Kevin; Yokota, Tomohiro; Singh, Neha; Dooraghi, Mojdeh; Abiri, Parinaz; Wang, Yibin; Kulkarni, Rajan P.; Nakano, Atsushi; Nguyen, Thao P.; Fei, Peng; Hsiai, Tzung K.

    2017-01-01

    Light-sheet fluorescence microscopy (LSFM) serves to advance developmental research and regenerative medicine. Coupled with the paralleled advances in fluorescence-friendly tissue clearing technique, our cardiac LSFM enables dual-sided illumination to rapidly uncover the architecture of murine hearts over 10 by 10 by 10 mm3 in volume; thereby allowing for localizing progenitor differentiation to the cardiomyocyte lineage and AAV9-mediated expression of exogenous transmembrane potassium channels with high contrast and resolution. Without the steps of stitching image columns, pivoting the light-sheet and sectioning the heart mechanically, we establish a holistic strategy for 3-dimentional reconstruction of the “digital murine heart” to assess aberrant cardiac structures as well as the spatial distribution of the cardiac lineages in neonates and ion-channels in adults. PMID:28165052

  13. Light-sheet fluorescence imaging to localize cardiac lineage and protein distribution

    NASA Astrophysics Data System (ADS)

    Ding, Yichen; Lee, Juhyun; Ma, Jianguo; Sung, Kevin; Yokota, Tomohiro; Singh, Neha; Dooraghi, Mojdeh; Abiri, Parinaz; Wang, Yibin; Kulkarni, Rajan P.; Nakano, Atsushi; Nguyen, Thao P.; Fei, Peng; Hsiai, Tzung K.

    2017-02-01

    Light-sheet fluorescence microscopy (LSFM) serves to advance developmental research and regenerative medicine. Coupled with the paralleled advances in fluorescence-friendly tissue clearing technique, our cardiac LSFM enables dual-sided illumination to rapidly uncover the architecture of murine hearts over 10 by 10 by 10 mm3 in volume; thereby allowing for localizing progenitor differentiation to the cardiomyocyte lineage and AAV9-mediated expression of exogenous transmembrane potassium channels with high contrast and resolution. Without the steps of stitching image columns, pivoting the light-sheet and sectioning the heart mechanically, we establish a holistic strategy for 3-dimentional reconstruction of the “digital murine heart” to assess aberrant cardiac structures as well as the spatial distribution of the cardiac lineages in neonates and ion-channels in adults.

  14. 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.

  15. Bright Multicolor Bandgap Fluorescent Carbon Quantum Dots for Electroluminescent Light-Emitting Diodes.

    PubMed

    Yuan, Fanglong; Wang, Zhibin; Li, Xiaohong; Li, Yunchao; Tan, Zhan'ao; Fan, Louzhen; Yang, Shihe

    2017-01-01

    Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m(-2) , which is the best performance for CQD-based monochrome electroluminescent LEDs.

  16. 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.

  17. 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).

  18. 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.

  19. Photodynamic tumor therapy and on-line fluorescence spectroscopy after ALA administration using 633-nm light as therapeutic and fluorescence excitation radiation

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Kienle, Alwin; Boehncke, Wolf-Henning; Kaufmann, Roland; Rueck, Angelika C.; Meier, Thomas H.; Steiner, Rudolf W.

    1994-09-01

    Photodynamic therapy (PDT) and on-line fluorescence spectroscopy were carried out on human tumors after 5-aminolevulinic acid (ALA) administration using 633-nm light of a dye laser as therapeutic radiation and as fluorescence excitation radiation. This has the advantages of (1) enabling use of one laser for PDT and fluorescence diagnosis only, (2) enabling the possibility of on-line fluorescence measurements, and (3) exciting protoporphyrin molecules in deep tissue layers. Monte Carlo calculations were carried out to determine excitation and fluorescence phonon distribution in case of red and violet excitation radiation. The results show the possibility of depth-resolved measurements on the fluorophore distribution by variation of excitation wavelength. The high penetration depth of 633-nm radiation results in a higher ratio of the 700-nm protoporphyrin fluorescence of the xenotransplanted tumor It to Is compared with 407-nm excitation. No values greater than 1 for the ratio I/Is were found, however, in case of intravenous ALA injection even for red excitation. Therefore, a large amount of ALA will be metabolized in the skin and can cause photosensitivity of the patient when applied systematically. In contrast, protoporphyrin fluorescence limited to the pretreated skin area was detected in case of topically applied ALA to patients with mycosis funcoides and erythroplasy of Queyrat. The influence of remitted excitation light and of the spontaneous radiation from the laser as well as the possible excitation of foodbased degradation products of chlorophyll has to be considered in high-sensitivity fluorescence measurements.

  20. Discrimination of Dendrobium officinale and its common adulterants by combination of normal light and fluorescence microscopy.

    PubMed

    Chu, Chu; Yin, Huimin; Xia, Li; Cheng, Dongping; Yan, Jizhong; Zhu, Lin

    2014-03-24

    The stems of Dendrobium officinale Kimura et Migo, named Tie-pi-shi-hu, is one of the most endangered and precious species in China. Because of its various pharmacodynamic effects, D. officinale is widely recognized as a high-quality health food in China and other countries in south and south-east Asia. With the rising interest of D. officinale, its products have a high price due to a limited supply. This high price has led to the proliferation of adulterants in the market. To ensure the safe use of D. officinale, a fast and convenient method combining normal and fluorescence microscopy was applied in the present study to distinguish D. officinale from three commonly used adulterants including Zi-pi-shi-hu (D. devonianum), Shui-cao-shi-hu (D. aphyllum), Guang-jie-shi-hu (D. gratiosissimum). The result demonstrated that D. officinale could be identified by the characteristic "two hat-shaped" vascular bundle sheath observed under the fluorescence microscopy and the distribution of raphides under normal light microscopy. The other three adulterants could be discriminated by the vascular bundle differences and the distribution of raphides under normal light microscopy. This work indicated that combination of normal light and fluorescence microscopy is a fast and efficient technique to scientifically distinguish D. officinale from the commonly confused species.

  1. 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.

  2. 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.

  3. MRT letter: Auto-fluorescence by human alveolar macrophages after in vitro exposure to air pollution particles.

    PubMed

    Ghio, Andrew J; Sangani, Rahul G; Brighton, Luisa E; Carson, John L

    2010-06-01

    Macrophages from smokers demonstrate an increased auto-fluorescence. Similarly, auto-fluorescence follows in vitro exposure of macrophages to cigarette smoke condensate (i.e., the particulate fraction of cigarette smoke). The composition of particles in cigarette smoke can be comparable to air pollution particles. We tested the postulate that macrophages exposed to air pollution particles could demonstrate auto-fluorescence. Healthy nonsmoking and healthy smoking volunteers (both 18-40 years of age) underwent fiberoptic bronchoscopy with bronchoalveolar lavage and alveolar macrophages isolated. Macrophages were incubated at 37 degrees C in 5% CO(2) with either PBS or 100 microg/mL particle for both 1 and 24 h. Particles included a residual oil fly ash, Mt. St. Helens volcanic ash, and ambient air particles collected from St. Louis, Missouri and Salt Lake City, Utah. At the end of incubation, 50 microL of the cell suspension was cytocentrifuged and examined at modes for viewing fluorescein isothiocyanate (FITC) and rhodamine fluorescence. Both emission source air pollution particles demonstrated FITC and rhodamine auto-fluorescence at 1 and 24 h, but the signal following incubation of the macrophages with oil fly ash appeared greater. Similarly, the ambient particles were associated with auto-fluorescence by the alveolar macrophages and this appeared to be dose-dependent. We conclude that exposure of macrophages to air pollution particles can be associated with auto-fluorescence in the FITC and rhodamine modes.

  4. 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.

  5. High-efficiency fluorescent organic light-emitting devices using sensitizing hosts with a small singlet-triplet exchange energy.

    PubMed

    Zhang, Dongdong; Duan, Lian; Li, Chen; Li, Yilang; Li, Haoyuan; Zhang, Deqiang; Qiu, Yong

    2014-08-06

    Materials with small singlet-triplet splits (ΔEST s) are introduced as sensitizing hosts to excite fluorescent dopants, breaking the trade-off between small ΔEST and high radiative decay rates. A highly efficient orange-fluorescent organic light-emitting diode (OLED) is prepared, showing a maximum external quantum efficiency of 12.2%.

  6. Generation of extended light-sheets for single and multi-photon fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Purnapatra, Subhajit B.; Pratim Mondal, Partha

    2013-07-01

    We theoretically propose and computationally demonstrate the generation of extended light-sheet for fluorescence microscopy. This is made possible by the introduction of a specially designed double-window spatial filter that allows the light to pass through the periphery and center of a cylindrical lens. When illuminated with a plane wave, the proposed filter results in an extended depth-of-focus along with side-lobes which are due to other interferences in the transverse focal plane. Computational studies show a maximum extension of light-sheet by 3.38 times for single photon excitation and 3.68 times for multiphoton excitation as compared to state-of-art single plane illumination microscopy system. This technique may facilitate the study of large biological specimens (such as Zebrafish embryo and tissue) with high spatial resolution and reduced photobleaching.

  7. 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

  8. Light induced fluorescence evaluation: A novel concept for caries diagnosis and excavation.

    PubMed

    Gugnani, Neeraj; Pandit, Ik; Srivastava, Nikhil; Gupta, Monika; Gugnani, Shalini

    2011-10-01

    In the era of minimal invasive dentistry, every effort should be directed to preserve the maximum tooth structure during cavity preparation. However, while making cavities, clinicians usually get indecisive at what point caries excavation should be stopped, so as to involve only the infected dentin. Apparent lack of valid clinical markers, difficulties with the use of caries detector dyes and chemo mechanical caries removal systems carve out a need for an improved system, which would be helpful to differentiate between the healthy and infected dentin during caries excavation. Light induced fluorescence evaluation is a novel concept implicated for caries detection and for making decisions while cavity preparation. This paper describes a few cases that explain the clinical applicability of this concept, using the SoproLife camera that works on this principle. Autofluorescence masking effect was found to be helpful for caries detection and the red fluorescence in the treatment mode was found helpful in deciding 'when to stop the excavation process.' Light induced fluorescence evaluation - Diagnosis - Treatment concept concept can be used as a guide for caries detection and excavation. It also facilitates decision making for stopping the caries excavation so as to involve infected dentin only.

  9. Light sheet fluorescence microscopy for in situ cell interaction analysis in mouse lymph nodes.

    PubMed

    Abe, Jun; Ozga, Aleksandra J; Swoger, Jim; Sharpe, James; Ripoll, Jorge; Stein, Jens V

    2016-04-01

    Reactive lymph nodes (LNs) are sites where pMHC-loaded dendritic cells (DCs) interact with rare cognate T cells, leading to their clonal expansion. While DC interactions with T cell subsets critically shape the ensuing immune response, surprisingly little is known on their spatial orchestration at physiologically T cell low precursor frequencies. Light sheet fluorescence microscopy and one of its implementations, selective plane illumination microscopy (SPIM), is a powerful method to obtain precise spatial information of entire organs of 0.5-10mm diameter, the size range of murine LNs. Yet, its usefulness for immunological research has thus far not been comprehensively explored. Here, we have tested and defined protocols that preserve fluorescent protein function during lymphoid tissue clearing required for SPIM. Reconstructions of SPIM-generated 3D data sets revealed that calibrated numbers of adoptively transferred T cells and DCs are successfully detected at a single cell level within optically cleared murine LNs. Finally, we define parameters to quantify specific interactions between antigen-specific T cells and pMHC-bearing DCs in murine LNs. In sum, our studies describe the successful application of light sheet fluorescence microscopy to immunologically relevant tissues.

  10. Population inversion in fluorescing fragments of super-excited molecules inside an air filament

    NASA Astrophysics Data System (ADS)

    See-Leang, Chin; Huai-Liang, Xu

    2015-01-01

    An original idea is reviewed. When a molecule is pumped into a super-excited state, one of its decay channels is neutral dissociation. One or more of the neutral fragments will fluoresce. Hence, if a lower state of such fluorescing fragments was populated through other channels but with a lower probability, population inversion of the fluorescing fragments would be naturally realized. This idea seems to be validated, so far, by comparing published work on three hydrocarbon molecules, CH4, C2H2, C2H4, and water vapor, H2O. After super-excitation in a femtosecond laser filament in air mixed with these molecules, the fluorescence from the CH or OH fragments exhibits population inversion, i.e., amplified spontaneous emission was observed in the backscattering direction of the filament. Project supported by the Canada Research Chairs, the Natural Science and Engineering Research Council of Canada (NSERC), the FRQNT, the Canada Foundation for Innovation (CFI), the National Basic Research Program of China (Grant No. 2014CB921300), the National Natural Science Foundation of China (Grant No. 61235003), the Research Fund for the Doctoral Program of Higher Education of China, and the Scientific Research Foundation for Returned Scholars, Ministry of Education of China.

  11. 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

  12. NMDA potentiation by visible light in the presence of a fluorescent neurosteroid analogue.

    PubMed

    Eisenman, Lawrence N; Shu, Hong-Jin; Wang, Cunde; Aizenman, Elias; Covey, Douglas F; Zorumski, Charles F; Mennerick, Steven

    2009-06-15

    N-Methyl-D-aspartate (NMDA) receptors are widely studied because of their importance in synaptic plasticity and excitotoxic cell death. Here we report a novel method of potentiating NMDA receptors with fluorescence excited by blue (480 nm) light. In the presence of 300 nM of a (7-nitro-2,1,3-benzoxadiazol-4-yl) amino (NBD)-tagged neuroactive steroid carrier C2-NBD-(3alpha,5alpha)-3-hydroxypregnan-20-one (C2-NBD 3alpha5alphaP), responses of cultured hippocampal neurons to 10 microM NMDA were potentiated to 219.2 +/- 9.2% of the baseline response (100%) by a 30 s exposure to 480 nm light. The potentiation decayed back to baseline with a time constant of 80.6 s. Responses to 1 microM and 100 microM NMDA were potentiated to 147.9 +/- 9.6% and 174.1 +/- 15.6% of baseline, respectively, suggesting that visible-light potentiation is relatively insensitive to NMDA concentration. Peak autaptic NMDA responses were potentiated to 178.9 +/- 22.4% of baseline. Similar potentiation was seen with 10 microM NBD-lysine, suggesting that visible-light potentiation is not a steroid effect. Potentiation was also seen with a steroid analogue in which the NBD was replaced with fluorescein, suggesting that NBD is not the only fluorophore capable of supporting visible-light potentiation. UV light and redox potentiation of NMDA receptors largely occluded subsequent blue light potentiation (127.7 +/- 7.4% and 120.2 +/- 6.2% of baseline, respectively). The NR1a(C744A,C798A) mutant that is insensitive to redox and UV potentiation was also largely unaffected by visible-light potentiation (135.0 +/- 10.0% of baseline). Finally, we found that the singlet oxygen scavenger furfuryl alcohol decreased visible-light potentiation. Collectively, these data suggest that visible-light potentiation of NMDA receptors by fluorescence excitation shares mechanisms with UV and redox potentiation and may involve singlet oxygen production.

  13. Lifetime of fluorescence from light-harvesting chlorophyll a/b proteins: excitation intensity dependence

    SciTech Connect

    Nordlund, T.M.; Knox, W.H.

    1981-10-01

    The fluorescence from a purified, aggregate form of the light-harvesting chlorophyll a/b protein has a lifetime of 1.2 +/- 0.5 ns at low excitation intensity, but the lifetime decreases significantly when the intensity of the 20-ps, 5300nm excitation pulse is increased above about 10/sup 16/ photons/cm/sup 2/. A solubilized, monomeric form of the protein, on the other hand, has a fluorescence lifetime of 3.1 +/- 0.3 ns independent of excitation intensity from 10/sup 14/-10/sup 18/ photons/cm/sup 2//pulse. We interpret the lifetime shortening in the aggregates and the lack of shortening in monomers in terms of exciton annihilation, facilitated in the aggregate by the larger population of interacting chlorophylls.

  14. Resolving the depth of fluorescent light by structured illumination and shearing interferometry

    NASA Astrophysics Data System (ADS)

    Schindler, Johannes; Elmaklizi, Ahmed; Voit, Florian; Hohmann, Ansgar; Schau, Philipp; Brodhag, Nicole; Krauter, Philipp; Frenner, Karsten; Kienle, Alwin; Osten, Wolfgang

    2016-03-01

    A method for the depth-sensitive detection of fluorescent light is presented. It relies on a structured illumination restricting the excitation volume and on an interferometric detection of the wave front curvature. The illumination with two intersecting beams of a white-light laser separated in a Sagnac interferometer coupled to the microscope provides a coarse confinement in lateral and axial direction. The depth reconstruction is carried out by evaluating shearing interferograms produced with a Michelson interferometer. This setup can also be used with spatially and temporally incoherent light as emitted by fluorophores. A simulation workflow of the method was developed using a combination of a solution of Maxwell's equations with the Monte Carlo method. These simulations showed the principal feasibility of the method. The method is validated by measurements at reference samples with characterized material properties, locations and sizes of fluorescent regions. It is demonstrated that sufficient signal quality can be obtained for materials with scattering properties comparable to dental enamel while maintaining moderate illumination powers in the milliwatt range. The depth reconstruction is demonstrated for a range of distances and penetration depths of several hundred micrometers.

  15. 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.

  16. 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.

  17. Spatial distribution of single-photon and two-photon fluorescence light in scattering media: Monte Carlo simulation.

    PubMed

    Gan, X; Gu, M

    2000-04-01

    Three-dimensional fluorescence spatial distributions under single-photon and two-photon excitation within a turbid medium are studied with Monte Carlo simulation. It is demonstrated that two-photon excitation has an advantage of producing much less fluorescence light outside the focal region compared with single-photon excitation. With the increase of the concentration of scattering particles in a turbid medium, the position of the maximum fluorescence intensity point shifts from the geometric focal region toward the medium surface. Further studies show that the optical sectioning property of two-photon fluorescence microscopy is degraded in thick turbid media or when the numerical aperture of an objective becomes low.

  18. Exposure to Fluorescent Light Triggers Down Regulation of Genes Involved with Mitotic Progression in Xiphophorus Skin

    PubMed Central

    Walter, Ronald B.; Walter, Dylan J.; Boswell, William T.; Caballero, Kaela L.; Boswell, Mikki; Lu, Yuan; Chang, Jordan; Savage, Markita G.

    2015-01-01

    We report RNA-Seq results from skin of X. maculatus Jp 163 B after exposure to various doses of “cool white” fluorescent light (FL). We show that FL exposure incites a genetic transcriptional response in skin nearly as great as observed for UVB exposure; however, the gene sets modulated due to exposure to the two light sources are quite different. Known light responsive genes involved in maintaining circadian cycling (e.g., clock, cry2a, cry1b, per1b, per2, per3, arntl1a, etc.) exhibited expected shifts in transcriptional expression upon FL exposure. Exposure to FL also resulted in down-regulated transcription of many genes involved with cell cycle progression (e.g., cdc20, cdc45, cdca7b, plk1, cdk1, ccnb-3, cdca7a, etc.) and chromosome segregation (e.g., cenpe, cenpf, cenpi, cenpk, cenpo, cenpp, and cenpu; cep70; knstrm, kntc, mcm2, mcm5; smc2, etc.). In addition, several DNA replication and recombination repair genes (e.g., pola1, pole, rec52, rad54l, rpa1, parpbp, etc.) exhibit reduced expression in FL exposed X. maculatus skin. Some genes down modulated by FL are known to be associated with DNA repair and human diseases (e.g., atm2, brip1, fanc1, fancl, xrcc4, etc.). The overall suppression of genes involved with mitotic progression in the skin of adult fish is consistent with entry into the light phase of the circadian cycle. Current efforts are aimed at determining specific wavelengths that may lead to differential expression among the many genes affected by fluorescent light exposure. PMID:26334372

  19. 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.

  20. 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.

  1. Light propagation from fluorescent probes in biological tissues by coupled time-dependent parabolic simplified spherical harmonics equations

    PubMed Central

    Domínguez, Jorge Bouza; Bérubé-Lauzière, Yves

    2011-01-01

    We introduce a system of coupled time-dependent parabolic simplified spherical harmonic equations to model the propagation of both excitation and fluorescence light in biological tissues. We resort to a finite element approach to obtain the time-dependent profile of the excitation and the fluorescence light fields in the medium. We present results for cases involving two geometries in three-dimensions: a homogeneous cylinder with an embedded fluorescent inclusion and a realistically-shaped rodent with an embedded inclusion alike an organ filled with a fluorescent probe. For the cylindrical geometry, we show the differences in the time-dependent fluorescence response for a point-like, a spherical, and a spherically Gaussian distributed fluorescent inclusion. From our results, we conclude that the model is able to describe the time-dependent excitation and fluorescent light transfer in small geometries with high absorption coefficients and in nondiffusive domains, as may be found in small animal diffuse optical tomography (DOT) and fluorescence DOT imaging. PMID:21483606

  2. Effect of light-emitting diode vs. fluorescent lighting on laying hens in aviary hen houses: Part 1 - Operational characteristics of lights and production traits of hens.

    PubMed

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

    2016-01-01

    Light-emitting diode (LED) lights are becoming more affordable for agricultural applications. Despite many lab-scale studies concerning impact of LED on poultry, little research has been documented under field production conditions, especially for laying hens. This 15-month field study was carried out to evaluate the effects of LED vs. fluorescent (FL) lights on laying hens (Dekalb white breed) using 4 (2 pairs) aviary hen houses each at a nominal capacity of 50,000 hens. The evaluation was done regarding operational characteristics of the lights and hen production traits. The results show that spatial distribution of the LED light was less uniform than that of the FL light. Light intensity of the LED light decreased by 27% after 3,360 h use but remained quite steady from 3,360 to 5,760 h use. Eleven out of 762 (1.44%) LED lamps (new at onset of the study) in the 2 houses failed during the 15-month experiment period. The neck area of the LED lamp was hottest, presumably the primary reason for the lamp failure as cracks were noticed in the neck region of all failed LED lamps. No differences were observed in egg weight, hen-day egg production, feed use, and mortality rate between LED and FL regimens. However, hens under the FL had higher eggs per hen housed and better feed conversion than those under the LED during 20 to 70 wk production (P < 0.05). Hens under the LED tended to have less feather uniformity and insulation than those under the FL (P < 0.05). Moreover, hens under the LED showed a larger median avoidance distance than those under the FL at 36 wk age (P < 0.05), indicating that hens under the LED were more alert; but no difference at 60 wk age. More comparative research to quantify behavioral and production responses of different breeds of hens to LED vs. FL lighting seems warranted.

  3. 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

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. 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.

  9. Development and application of fluorescent, green light-activatable caged compound

    NASA Astrophysics Data System (ADS)

    Umeda, Nobuhiro; Urano, Yasuteru; Nagano, Tetsuo

    2011-03-01

    Caged compound is one of the most powerful tools for spatiotemporal control of biomolecules in cells, which can be activated by irradiation of light. However, ultra violet light, which is required for activation of caged compounds, can damage cells and has poor permeability into tissues. In addition, invisibility of caged compounds makes it difficult to tell distribution of released small molecules. At the conference, we will describe the development of novel caging group and new caged compounds which are fluorescently visible and efficiently activatable with green light. We have found that boron dipyrromethene (BODIPY), known as a widely used fluorophore, is a potential caging group for phenol, carboxyl acid and amine, which can be photolized with irradiation of green light at around 500 nm wavelength. Based on the novel photo-reaction of 4-phenoxy BODIPY derivatives, we have developed caged histamine and applied it to HeLa cells. Photo-irradiation to cells in the presence of caged histamine induced transient increase of calcium ion in cytosol, which was specifically inhibited with pyrilamine, a H1 blocker. Also, we showed that BODIPY-caged compound can be utilized in vivo with tissue-permeable 500 nm green light.

  10. 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.

  11. Light stress effect and by nitrogen deficiency in plants of Petiveria alliacea measured with two-chlorophyll-fluorescence technique

    NASA Astrophysics Data System (ADS)

    Zuluaga, H.; Oviedo, A.; Solarte, Efrain; Pena, E. J.

    2004-10-01

    The chlorophyll fluorescence was studied in Petiveria alliacea plants exposed to different nitrogen concentrations and light radiation, the response was measured by two different forms; (1) measuring the photosynthetic efficiency with a pulse amplitude modulated fluorometro (PAM) emitted by a 650 nm diode and (2) measuring the fluorescence spectra caused by high power 452 nm diode with a SD2000 spectrometer. It was found out that the photosynthetic efficiency decreased in the plants exposed to high radiance and low nitrogen. Two chlorophyll fluorescence peaks were observed on 684 nm and 739 nm, the intensities in this wavelengths are inversely related with the light radiance. The correlation between the FIR and photosynthetic efficiency was very strong (r2 = -0.809, p <<0.01) this let us conclude that the fluorescence spectral analysis induced by the diode (excitation at 452 nm) is an efficient technique to detect stress by high light intensity and nitrogen in P. Alliacea plants.

  12. Fluorescent light activates the immunomodulator cis-urocanic acid in vitro: implications for patients with systemic lupus erythematosus.

    PubMed Central

    McGrath, H; Bell, J M; Haycock, J W

    1994-01-01

    OBJECTIVE--Erythemagenic (295-305 nm) ultraviolet-B (UVB) radiation is toxic to patients with systemic lupus erythematosus (SLE). Cool white fluorescent lamp emissions produce a similar toxicity even though the UVB radiation emitted is primarily at the relatively non-erythemagenic wavelength of 313 nm. The purpose of this study was to determine if fluorescent light, presumably acting predominantly along the 313 nm wavelength, exhibits photochemical activity sufficient to account for toxicity. METHODS--The photochemical activity of fluorescent light was assessed by testing its capacity to activate urocanic acid, a plentiful and potent epidermal immunological mediator normally activated by polychromatic UVB radiation but activated maximally at 313 nm. Irradiation-induced isomerisation of trans-urocanic to cis-urocanic acid was quantitated by UV spectroscopy after separation of the isomers by high performance liquid chromatography. RESULTS--Fluorescent light irradiation of solutions containing the photoreceptor trans-urocanic acid produced a cumulative conversion of trans-to-cis-urocanic acid. This photochemical activity was compared with that of erythemagenic sunlamps, high in polychromatic UVB emissions. When normalised for UVB irradiance, the accumulation of cis-urocanic acid produced by both light sources was essentially equivalent. Conventional acrylic diffusers that absorb UVB emissions eliminated the fluorescent light-induced reaction. CONCLUSION--The results indicate that radiation from fluorescent lamps possesses substantial photoimmunological capability, sufficient to activate a potent, potentially dangerous, disease-modifying, immunomodulatory pathway and that poorly erythemagenic, primarily monochromatic UVB photons are responsible. PMID:8037497

  13. Developing a genetically encoded green fluorescent protein mutant for sensitive light-up fluorescent sensing and cellular imaging of Hg(II).

    PubMed

    Jiang, Tao; Guo, Daiping; Wang, Qian; Wu, Xin; Li, Zhao; Zheng, Zhenhua; Yin, Boyuan; Xia, Lin; Tang, Jixian; Luo, Wenxin; Xia, Ningshao; Jiang, Yunbao

    2015-05-30

    Hg(II) is well-known for quenching fluorescence in a distance dependent manner. Nevertheless, when we exposed the fluorophore of a green fluorescent protein (GFP) toward Hg(II), through H148C mutation, the GFP fluorescence could be "lighted up" by Hg(II) down to sub-nM level. The detection linear range is 0.5-3.0 nM for protein solutions at 8.0 nM. The GFPH148C protein displayed a promising selectivity toward Hg(II) and also the cellular imaging capacity. Spectra measurements suggested that the ground-state redistribution of protein contributed to the fluorescence enhancement, which was found not limited to Hg(II), and thus presented an opening for building a pool of GFP-based chemosensors toward other heavy metal ions.

  14. Far-red light activatable, multifunctional prodrug for fluorescence optical imaging and combinational treatment.

    PubMed

    Bio, Moses; Rajaputra, Pallavi; Nkepang, Gregory; You, Youngjae

    2014-04-24

    We recently developed "photo-unclick chemistry", a novel chemical tool involving the cleavage of aminoacrylate by singlet oxygen, and demonstrated its application to visible light-activatable prodrugs. In this study, we prepared an advanced multifunctional prodrug, Pc-(L-CA4)2, composed of the fluorescent photosensitizer phthalocyanine (Pc), an SO-labile aminoacrylate linker (L), and a cytotoxic drug combretastatin A-4 (CA4). Pc-(L-CA4)2 had reduced dark toxicity compared with CA4. However, once illuminated, it showed improved toxicity similar to CA4 and displayed bystander effects in vitro. We monitored the time-dependent distribution of Pc-(L-CA4)2 using optical imaging with live mice. We also effectively ablated tumors by the illumination with far-red light to the mice, presumably through the combined effects of photodynamic therapy (PDT) and released chemotherapy drug, without any sign of acute systemic toxicity.

  15. 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.

  16. Impact of Fluorescent Lighting on Oxidation of Model Wine Solutions Containing Organic Acids and Iron.

    PubMed

    Grant-Preece, Paris; Barril, Celia; Schmidtke, Leigh M; Clark, Andrew C

    2017-03-22

    Previous studies have provided evidence that light exposure can increase oxygen consumption in wine and that the photodegradation of iron(III) tartrate could contribute to this process. In the present study, model wine solutions containing iron(III) and various organic acids, either alone or combined, were stored in sealed clear glass wine bottles and exposed to light from fluorescent lamps. Dissolved oxygen was monitored, and afterward the organic acid degradation products were determined and the capacity of the solutions to bind sulfur dioxide, the main wine preservative, was assessed. In the dark controls, little or no dissolved oxygen was consumed and the organic acids were stable. In the irradiated solutions, dissolved oxygen was consumed at a rate that was dependent on the specific organic acid present, and the latter were oxidized to various carbonyl compounds. For the solutions containing tartaric acid, malic acid, and/or citric acid, irradiation increased their sulfur dioxide-binding capacity.

  17. Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes.

    PubMed

    Wong, Michael Y; Zysman-Colman, Eli

    2017-03-03

    The design of thermally activated delayed fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting, as these new materials offer the possibility of developing low-cost lighting and displays. Here, a comprehensive review of TADF materials is presented, with a focus on linking their optoelectronic behavior with the performance of the organic light-emitting diode (OLED) and related EL devices. TADF emitters are cross-compared within specific color ranges, with a focus on blue, green-yellow, orange-red, and white OLEDs. Organic small-molecule, dendrimer, polymer, and exciplex emitters are all discussed within this review, as is their use as host materials. Correlations are provided between the structure of the TADF materials and their optoelectronic properties. The success of TADF materials has ushered in the next generation of OLEDs.

  18. Far-Red Light Activatable, Multifunctional Prodrug for Fluorescence Optical Imaging and Combinational Treatment

    PubMed Central

    2015-01-01

    We recently developed “photo-unclick chemistry”, a novel chemical tool involving the cleavage of aminoacrylate by singlet oxygen, and demonstrated its application to visible light-activatable prodrugs. In this study, we prepared an advanced multifunctional prodrug, Pc-(L-CA4)2, composed of the fluorescent photosensitizer phthalocyanine (Pc), an SO-labile aminoacrylate linker (L), and a cytotoxic drug combretastatin A-4 (CA4). Pc-(L-CA4)2 had reduced dark toxicity compared with CA4. However, once illuminated, it showed improved toxicity similar to CA4 and displayed bystander effects in vitro. We monitored the time-dependent distribution of Pc-(L-CA4)2 using optical imaging with live mice. We also effectively ablated tumors by the illumination with far-red light to the mice, presumably through the combined effects of photodynamic therapy (PDT) and released chemotherapy drug, without any sign of acute systemic toxicity. PMID:24694092

  19. Fluorescent chlorophyll catabolites in bananas light up blue halos of cell death.

    PubMed

    Moser, Simone; Müller, Thomas; Holzinger, Andreas; Lütz, Cornelius; Jockusch, Steffen; Turro, Nicholas J; Kräutler, Bernhard

    2009-09-15

    Breakdown of chlorophyll is a major contributor to the diagnostic color changes in fall leaves, and in ripening apples and pears, where it commonly provides colorless, nonfluorescent tetrapyrroles. In contrast, in ripening bananas (Musa acuminata) chlorophylls fade to give unique fluorescent catabolites (FCCs), causing yellow bananas to glow blue, when observed under UV light. Here, we demonstrate the capacity of the blue fluorescent chlorophyll catabolites to signal symptoms of programmed cell death in a plant. We report on studies of bright blue luminescent rings on the peel of very ripe bananas, which arise as halos around necrotic areas in 'senescence associated' dark spots. These dark spots appear naturally on the peel of ripe bananas and occur in the vicinity of stomata. Wavelength, space, and time resolved fluorescence measurements allowed the luminescent areas to be monitored on whole bananas. Our studies revealed an accumulation of FCCs in luminescent rings, within senescing cells undergoing the transition to dead tissue, as was observable by morphological textural cellular changes. FCCs typically are short lived intermediates of chlorophyll breakdown. In some plants, FCCs are uniquely persistent, as is seen in bananas, and can thus be used as luminescent in vivo markers in tissue undergoing senescence. While FCCs still remain to be tested for their own hypothetical physiological role in plants, they may help fill the demand for specific endogenous molecular reporters in noninvasive assays of plant senescence. Thus, they allow for in vivo studies, which provide insights into critical stages preceding cell death.

  20. Retrieving the axial position of fluorescent light emitting spots by shearing interferometry

    NASA Astrophysics Data System (ADS)

    Schindler, Johannes; Schau, Philipp; Brodhag, Nicole; Frenner, Karsten; Osten, Wolfgang

    2016-12-01

    A method for the depth-resolved detection of fluorescent radiation based on imaging of an interference pattern of two intersecting beams and shearing interferometry is presented. The illumination setup provides the local addressing of the excitation of fluorescence and a coarse confinement of the excitation volume in axial and lateral directions. The reconstruction of the depth relies on the measurement of the phase of the fluorescent wave fronts. Their curvature is directly related to the distance of a source to the focus of the imaging system. Access to the phase information is enabled by a lateral shearing interferometer based on a Michelson setup. This allows the evaluation of interference signals even for spatially and temporally incoherent light such as emitted by fluorophors. An analytical signal model is presented and the relations for obtaining the depth information are derived. Measurements of reference samples with different concentrations and spatial distributions of fluorophors and scatterers prove the experimental feasibility of the method. In a setup optimized for flexibility and operating in the visible range, sufficiently large interference signals are recorded for scatterers placed in depths in the range of hundred micrometers below the surface in a material with scattering properties comparable to dental enamel.

  1. 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

  2. Fluorescent chlorophyll catabolites in bananas light up blue halos of cell death

    PubMed Central

    Moser, Simone; Müller, Thomas; Holzinger, Andreas; Lütz, Cornelius; Jockusch, Steffen; Turro, Nicholas J.; Kräutler, Bernhard

    2009-01-01

    Breakdown of chlorophyll is a major contributor to the diagnostic color changes in fall leaves, and in ripening apples and pears, where it commonly provides colorless, nonfluorescent tetrapyrroles. In contrast, in ripening bananas (Musa acuminata) chlorophylls fade to give unique fluorescent catabolites (FCCs), causing yellow bananas to glow blue, when observed under UV light. Here, we demonstrate the capacity of the blue fluorescent chlorophyll catabolites to signal symptoms of programmed cell death in a plant. We report on studies of bright blue luminescent rings on the peel of very ripe bananas, which arise as halos around necrotic areas in ‘senescence associated’ dark spots. These dark spots appear naturally on the peel of ripe bananas and occur in the vicinity of stomata. Wavelength, space, and time resolved fluorescence measurements allowed the luminescent areas to be monitored on whole bananas. Our studies revealed an accumulation of FCCs in luminescent rings, within senescing cells undergoing the transition to dead tissue, as was observable by morphological textural cellular changes. FCCs typically are short lived intermediates of chlorophyll breakdown. In some plants, FCCs are uniquely persistent, as is seen in bananas, and can thus be used as luminescent in vivo markers in tissue undergoing senescence. While FCCs still remain to be tested for their own hypothetical physiological role in plants, they may help fill the demand for specific endogenous molecular reporters in noninvasive assays of plant senescence. Thus, they allow for in vivo studies, which provide insights into critical stages preceding cell death. PMID:19805212

  3. 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.

  4. Nuclear export of single native mRNA molecules observed by light sheet fluorescence microscopy.

    PubMed

    Siebrasse, Jan Peter; Kaminski, Tim; Kubitscheck, Ulrich

    2012-06-12

    Nuclear export of mRNA is a key transport process in eukaryotic cells. To investigate it, we labeled native mRNP particles in living Chironomus tentans salivary gland cells with fluorescent hrp36, the hnRNP A1 homolog, and the nuclear envelope by fluorescent NTF2. Using light sheet microscopy, we traced single native mRNA particles across the nuclear envelope. The particles were observed to often probe nuclear pore complexes (NPC) at their nuclear face, and in only 25% of the cases yielded actual export. The complete export process took between 65 ms up to several seconds. A rate-limiting step was observed, which could be assigned to the nuclear basket of the pore and might correspond to a repositioning and unfolding of mRNPs before the actual translocation. Analysis of single fluorescent Dbp5 molecules, the RNA helicase essential for mRNA export, revealed that Dbp5 most often approached the cytoplasmic face of the NPC, and exhibited a binding duration of approximately 55 ms. Our results have allowed a refinement of the current models for mRNA export.

  5. Effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy under an artificial lighting condition.

    PubMed

    Kitaya, Y; Shibuya, T; Kozai, T; Kubota, C

    1998-01-01

    In order to characterize environmental variables inside a plant canopy under artificial lighting in the CELSS, we investigated the effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy. Under a PPF of 500 micromoles m-2 s-1, air temperature was 2-3 degrees C higher, water vapor pressure was 0.6 kPa higher, and CO2 concentration was 25-35 micromoles mol-1 lower at heights ranging from 0 to 30 mm below the canopy than at a height 60 mm above the canopy. Increasing the PPF increased air temperature and water vapor pressure and decreased CO2 concentration inside the canopy. The air temperature was lower and the CO2 concentration was higher inside the canopy at an air velocity of 0.3 m s-1 than at an air velocity of 0.1 m s-1. The environmental variables inside the canopy under a high light intensity were characterized by higher air temperature, higher vapor pressure, and lower CO2 concentration than those outside the canopy.

  6. In vitro quantitative light-induced fluorescence to measure changes in enamel mineralization.

    PubMed

    Gmür, Rudolf; Giertsen, Elin; van der Veen, Monique H; de Josselin de Jong, Elbert; ten Cate, Jacob M; Guggenheim, Bernhard

    2006-09-01

    A sensitive, quantitative method for investigating changes in enamel mineralization of specimens subjected to in vitro or in situ experimentation is presented. The fluorescence-detecting instrument integrates a Xenon arc light source and an object positioning stage, which makes it particularly suitable for the nondestructive assessment of demineralized or remineralized enamel. We demonstrate the ability of in vitro quantitative light-induced fluorescence (QLF) to quantify changes in mineralization of bovine enamel discs that had been exposed in vitro to a demineralizing gel (n=36) or biofilm-mediated demineralization challenges (n=10), or were carried in situ by three volunteers during a 10-day experiment (n=12). Further experiments show the technique's value for monitoring the extent of remineralization in 36 specimens exposed in vitro to oral multispecies biofilms and document the repeatability of in vitro QLF measurements (n=10) under standardized assay conditions. The validity of the method is illustrated by comparison with transversal microradiography (TMR), the invasive current gold standard for assessing experimental changes in enamel mineralization. Ten discs with 22 measurement areas for comparison demonstrated a positive correlation between TMR and QLF (r=0.82). Filling a technological gap, this QLF system is a promising tool to assay in vitro nondestructively localized changes in mineralization of enamel specimens.

  7. In Vivo Lighted Fluorescence via Fenton Reaction: Approach for Imaging of Hydrogen Peroxide in Living Systems.

    PubMed

    Liu, Changhui; Chen, Weiju; Qing, Zhihe; Zheng, Jing; Xiao, Yue; Yang, Sheng; Wang, Lili; Li, Yinhui; Yang, Ronghua

    2016-04-05

    By virtue of its high sensitivity and rapidity, Fenton reaction has been demonstrated as a powerful tool for in vitro biochemical analysis; however, in vivo applications of Fenton reaction still remain to be exploited. Herein, we report, for the first time, the design, formation and testing of Fenton reaction for in vivo fluorescence imaging of hydrogen peroxide (H2O2). To realize in vivo fluorescence imaging of H2O2 via Fenton reaction, a functional nanosphere, Fc@MSN-FDNA/PTAD, is fabricated from mesoporous silica nanoparticle (MSN), a Fenton reagent of ferrocene (Fc), ROX-labeled DNA (FDNA), and a cationic perylene derivative (PTAD). The ferrocene molecules are locked in the pore entrances of MSN, and exterior of MSN is covalently immobilized with FDNA. As a key part, PTAD acts as not only the gatekeeper of MSN but also the efficient quencher of ROX. H2O2 can permeate into the nanosphere and react with ferrocene to product hydroxyl radical (·OH) via Fenton reaction, which cleaves FDNA to detach ROX from PTAD, thus in turn, lights the ROX fluorescence. Under physiological condition, H2O2 can be determined from 5.0 nM to 1.0 μM with a detection limit of 2.4 nM. Because of the rapid kinetics of Fenton reaction and high specificity for H2O2, the proposed method meets the requirement for real applications. The feasibility of Fc@MSN-FDNA/PTAD for in vivo applications is demonstrated for fluorescence imaging of exogenous and endogenous H2O2 in cells and mice. We expect that this work will not only contribute to the H2O2-releated studies but also open up a new way to exploit in vivo Fenton reaction for biochemical research.

  8. 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

  9. Light illumination and detection patterns for fluorescence diffuse optical tomography based on compressive sensing.

    PubMed

    Jin, An; Yazici, Birsen; Ntziachristos, Vasilis

    2014-06-01

    Fluorescence diffuse optical tomography (FDOT) is an emerging molecular imaging modality that uses near infrared light to excite the fluorophore injected into tissue; and to reconstruct the fluorophore concentration from boundary measurements. The FDOT image reconstruction is a highly ill-posed inverse problem due to a large number of unknowns and limited number of measurements. However, the fluorophore distribution is often very sparse in the imaging domain since fluorophores are typically designed to accumulate in relatively small regions. In this paper, we use compressive sensing (CS) framework to design light illumination and detection patterns to improve the reconstruction of sparse fluorophore concentration. Unlike the conventional FDOT imaging where spatially distributed light sources illuminate the imaging domain one at a time and the corresponding boundary measurements are used for image reconstruction, we assume that the light sources illuminate the imaging domain simultaneously several times and the corresponding boundary measurements are linearly filtered prior to image reconstruction. We design a set of optical intensities (illumination patterns) and a linear filter (detection pattern) applied to the boundary measurements to improve the reconstruction of sparse fluorophore concentration maps. We show that the FDOT sensing matrix can be expressed as a columnwise Kronecker product of two matrices determined by the excitation and emission light fields. We derive relationships between the incoherence of the FDOT forward matrix and these two matrices, and use these results to reduce the incoherence of the FDOT forward matrix. We present extensive numerical simulation and the results of a real phantom experiment to demonstrate the improvements in image reconstruction due to the CS-based light illumination and detection patterns in conjunction with relaxation and greedy-type reconstruction algorithms.

  10. 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.

  11. State transitions and fluorescence quenching in the cyanobacterium Synechocystis PCC 6803 in response to changes in light quality and intensity.

    PubMed

    Zhao, Wenfeng; Xie, Jie; Xu, Xiuling; Zhao, Jingquan

    2015-01-01

    State transition and non-photochemical fluorescence quenching in cyanobacteria are short-term adaptations of photosynthetic apparatus to changes in light quality and intensity, however, the kinetic details and relationship are still not clear. In this work, time-dependent 77K fluorescence spectra were monitored for cyanobacterium Synechocystis PCC 6803 cells under blue, orange and blue-green light in a series of intensities. The characteristic fluorescence signals indicated state transition taking place exclusively under 430-450 or 580-600nm light or 480-550nm light at the intensities ⩽150μEm(-2)s(-1) to achieve a conserved level with variable rate constant. Under 480-500nm or 530-550nm light at the intensities ⩾160μEm(-2)s(-1), state transition took place at first but stopped as soon as the fluorescence quenching appeared. The dependence of appearance, induction period, level and rate constant for the quenching on light intensity suggests that a critical concentration of photo-activated OCPs is necessary and may be achieved by a dynamic equilibrium between the activation and deactivation under light.

  12. The small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield of cosmic ray shower particles

    NASA Astrophysics Data System (ADS)

    Al Samarai, Imen; Deligny, Olivier; Rosado, Jaime

    2016-10-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C 3Πu electronic level of nitrogen molecules to the B 3Πg one amounting to Y[ 337 ] =(6.05 ± 1.50) MeV-1 at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be Y[330-400]MBR = 0.10 MeV-1 in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This means that out of ≃175 photons with wavelength between 330 and 400 nm detected by fluorescence detectors, one of them has been produced by molecular Bremsstrahlung radiation. Although small, this contribution is not negligible in regards to the total budget of systematic uncertainties when considering the absolute energy scale of fluorescence detectors.

  13. 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.

  14. 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

  15. Replacement of fluorescent lamps with high-brightness LEDs in a bridge lighting application

    NASA Astrophysics Data System (ADS)

    Curran, John W.; Keeney, Shawn P.

    2006-08-01

    There are many advantages that LEDs offer for use in general illumination. The use of LEDs in certain applications can provide improved energy efficiency. For example, in traffic lights in the United States, LED technology has taken over the market not only because of the energy savings as compared to standard incandescents, but also because of the reduced maintenance costs associated with bulb replacement and improved reliability. With useful lifetimes exceeding 40,000 hours or more, today's high flux LEDs can provide illumination solutions with replacement periods of 8 to 10 years or more. This paper will examine a bridge roadway lighting feasibility study which the authors' company recently undertook. The application required the LED units to reproduce the photometric performance of 64-inch (1.625m) fluorescent lamps. In addition, the LED units were required to survive a harsh, outdoor marine environment with an expected lifetime of 7 years or more. To achieve these results, a number of design elements were studied including: optimum heat dissipation in a sealed enclosure, ease of installation, and design of power supplies having expected lifetimes to match the LED light engines. Results of these studies will be discussed as well as illustrations of the designs chosen.

  16. 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.

  17. Visible-light optical coherence tomography-based multimodal retinal imaging for improvement of fluorescent intensity quantification

    PubMed Central

    Nafar, Zahra; Jiang, Minshan; Wen, Rong; Jiao, Shuliang

    2016-01-01

    We developed a spectral-domain visible-light optical coherence tomography (VIS-OCT) based multimodal imaging technique which can accomplish simultaneous OCT and fluorescence imaging with a single broadband light source. Phantom experiments showed that by using the simultaneously acquired OCT images as a reference, the effect of light attenuation on the intensity of the fluorescent images by materials in front of the fluorescent target can be compensated. This capability of the multimodal imaging technique is of high importance for achieving quantification of the true intensities of autofluorescence (AF) imaging of the retina. We applied the technique in retinal imaging including AF imaging of the retinal pigment epithelium and fluorescein angiography (FA). We successfully demonstrated the effect of compensation on AF and FA images with the simultaneously acquired VIS-OCT images. PMID:27699094

  18. Enhanced photocatalytic inactivation of bacteria on Fe-containing TiO2 nanoparticles under fluorescent light.

    PubMed

    Yadav, Hemraj M; Kolekar, Tanaji V; Pawar, Shivaji H; Kim, Jung-Sik

    2016-03-01

    In this paper, the photocatalytic activity of Fe-TiO2 nanoparticles (NPs) under fluorescent light was studied using Escherichia coli and Staphylococcus aureus. Fe-TiO2 NPs were synthesized using a sol-gel method and characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (UV-vis DRS) and transmission electron microscopy. The efficiency of photocatalytic inactivation towards E. coli was studied under different physicochemical parameters. The photocatalytic inactivation rate increased with increasing Fe content in TiO2 NPs and the highest inactivation was achieved for 3.0 mol% Fe-TiO2 NPs under fluorescent light. These results demonstrate that the presence of an optimum concentration of Fe in TiO2 matrix enhances the photocatalytic inactivation of TiO2 NPs under fluorescent light.

  19. [Use of laser flow-type fluorescence aerosol particle counter to evaluate the concentration of microbes in the surface air under high dust content].

    PubMed

    Kalinin, Iu T; Vorob'ev, S A; Khramov, E N; Vorob'eva, E A; Kuznetsov, A P; Kiselev, O S

    2000-01-01

    The paper deals with the use of a laser flow-type fluorescence aerosol particle counter to evaluate the concentrations of microbes in the surface air under high dust content. Various circuits of flow-type optic aerosol recorders are analyzed. Flow spectral luminescence analysis of some particles flow while exciting the fourth harmonics of a pulse laser on yttrium-aluminium garnet with neodymium by ultraviolet radiation is shown to be the most optimum method for indication of individual aerosol particles. Experiments were conducted on the authors' model of a pilot plant based on this method. The model of a laser flow-type optic analyzer was developed for experimental studies that give a clear display of biological aerosols in complex aerosols. The laser flow-type analyzer-based unit developed may provide a fluorescence signal of aerosol particles in the flow of a sample and that light diffusion signal from them at an exciting light wavelength of 266 nm. Experiments with BVC aerosols and soil dust particles were conducted in different regions of Russia. They showed it possible to detect and to rapidly calculate soil microorganisms by laser flow-type fluorescence assay of individual particles when excited by ultraviolet radiation.

  20. 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.

  1. Light Sheet Fluorescence Microscopy of Plant Roots Growing on the Surface of a Gel

    PubMed Central

    von Wangenheim, Daniel; Hauschild, Robert; Friml, Jiří

    2017-01-01

    One of the key questions in understanding plant development is how single cells behave in a larger context of the tissue. Therefore, it requires the observation of the whole organ with a high spatial- as well as temporal resolution over prolonged periods of time, which may cause photo-toxic effects. This protocol shows a plant sample preparation method for light-sheet microscopy, which is characterized by mounting the plant vertically on the surface of a gel. The plant is mounted in such a way that the roots are submerged in a liquid medium while the leaves remain in the air. In order to ensure photosynthetic activity of the plant, a custom-made lighting system illuminates the leaves. To keep the roots in darkness the water surface is covered with sheets of black plastic foil. This method allows long-term imaging of plant organ development in standardized conditions. PMID:28190052

  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. Assessing the Association between Oral Hygiene and Preterm Birth by Quantitative Light-Induced Fluorescence

    PubMed Central

    Hope, Christopher K.; Wang, Qian; Adeyemi, Adejumoke A.; Quenby, Siobhan; Smith, Philip W.; Higham, Susan M.; Whitworth, Melissa

    2014-01-01

    The aim of this study was to investigate the purported link between oral hygiene and preterm birth by using image analysis tools to quantify dental plaque biofilm. Volunteers (n = 91) attending an antenatal clinic were identified as those considered to be “at high risk” of preterm delivery (i.e., a previous history of idiopathic preterm delivery, case group) or those who were not considered to be at risk (control group). The women had images of their anterior teeth captured using quantitative light-induced fluorescence (QLF). These images were analysed to calculate the amount of red fluorescent plaque (ΔR%) and percentage of plaque coverage. QLF showed little difference in ΔR% between the two groups, 65.00% case versus 68.70% control, whereas there was 19.29% difference with regard to the mean plaque coverage, 25.50% case versus 20.58% control. A logistic regression model showed a significant association between plaque coverage and case/control status (P = 0.031), controlling for other potential predictor variables, namely, smoking status, maternal age, and body mass index (BMI). PMID:24511282

  4. Light induced fluorescence for predicting API content in tablets: sampling and error.

    PubMed

    Domike, Reuben; Ngai, Samuel; Cooney, Charles L

    2010-05-31

    The use of a light induced fluorescence (LIF) instrument to estimate the total content of fluorescent active pharmaceutical ingredient in a tablet from surface sampling was demonstrated. Different LIF sampling strategies were compared to a total tablet ultraviolet (UV) absorbance test for each tablet. Testing was completed on tablets with triamterene as the active ingredient and on tablets with caffeine as the active ingredient, each with a range of concentrations. The LIF instrument accurately estimated the active ingredient within 10% of total tablet test greater than 95% of the time. The largest error amongst all of the tablets tested was 13%. The RMSEP between the techniques was in the range of 4.4-7.9%. Theory of the error associated with the surface sampling was developed and found to accurately predict the experimental error. This theory uses one empirically determined parameter: the deviation of estimations at different locations on the tablet surface. As this empirical parameter can be found rapidly, correct use of this prediction of error may reduce the effort required for calibration and validation studies of non-destructive surface measurement techniques, and thereby rapidly determine appropriate analytical techniques for estimating content uniformity in tablets.

  5. 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.

  6. Robust measurement of membrane bending moduli using light sheet fluorescence imaging of vesicle fluctuations.

    PubMed

    Loftus, Andrew F; Noreng, Sigrid; Hsieh, Vivian L; Parthasarathy, Raghuveer

    2013-11-26

    The mechanical rigidity of lipid membranes is a key determinant of the energetics of cellular membrane deformation. Measurements of membrane bending moduli remain rare, however, and show a large variance, a situation that can be addressed by the development of improved techniques and by comparisons between disparate techniques applied to the same systems. We introduce here the use of selective plane illumination microscopy (SPIM, also known as light sheet fluorescence microscopy) to image thermal fluctuations of giant vesicles. The optical sectioning of SPIM enables high-speed fluorescence imaging of freely suspended vesicles and quantification of edge localization precision, yielding robust fluctuation spectra and rigidity estimates. For both lipid-only membranes and membranes bound by the intracellular trafficking protein Sar1p, which lowers membrane rigidity in a concentration-dependent manner, we show that the resulting bending modulus values are in close agreement with those derived from an independent assay based on membrane tether pulling. We also show that the fluctuation spectra of vesicles bound by the mammalian Sar1A protein, which stiffens membranes at high concentrations, are not well fit by a model of homogeneous quasi-spherical vesicles, suggesting that SPIM-based analysis can offer insights into spatially inhomogeneous properties induced by protein assemblies.

  7. Selective light-triggered chemiluminescence between fluorescent dyes and luminol, and its analytical application.

    PubMed

    Ma, Mingyang; Diao, Fangning; Zheng, Xingwang; Guo, Zhihui

    2012-08-01

    We report herein a novel chemiluminescence (CL) phenomenon triggered by light irradiation when a fluorescent dye, for example hematoporphyrin, fluorescein, eosin, or methylene blue is present in the luminol solution. A possible mechanism is proposed for the photoinduced chemiluminescence (PICL) reaction. Compared with reported methods for CL triggering, for example flow-injection, static reagent injection, and the electrochemical technique, the proposed in-situ PICL method presented has three advantages. First, the method is more selective, because the PICL signal of the target fluorescent dyes is initiated by excitation at a selective wavelength only. Second, the space and time resolution of the PICL method are better. Last, and most important, compared with injecting a reagent or inserting a electrode into the CL system to initiate the CL reaction, with the in-situ PICL method there is no physical interference with the target detecting system. All these advantages of the PICL method indicate it has many potential applications in the analytical sciences. The proposed method was applied to analysis of urine containing adrenaline. The linear range for adrenaline is 2.0 × 10(-10)-1.0 × 10(-7) g mL(-1) and the detection limit is 6.0 × 10(-11) g mL(-1).

  8. 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

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

    PubMed

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

    1994-08-01

    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.

  10. 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.

  11. 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.

  12. Light Sheet Fluorescence Microscopy Quantifies Calcium Oscillations in Root Hairs of Arabidopsis thaliana.

    PubMed

    Candeo, Alessia; Doccula, Fabrizio G; Valentini, Gianluca; Bassi, Andrea; Costa, Alex

    2017-03-31

    Calcium oscillations play a role in the regulation of the development of tip-growing plant cells. Using optical microscopy, calcium oscillations have been observed in a few systems (e.g. pollen tubes, fungal hyphae, algal rhizoids). High resolution, non-phototoxic and rapid imaging methods are required to study the calcium oscillation in root hairs. We show that Light Sheet Fluorescence Microscopy is optimal to image growing root hairs of Arabidopsis thaliana and to follow their oscillatory tip-focused calcium gradient. We describe a protocol for performing live imaging of root hairs in seedlings expressing the cytosolic localised ratiometric calcium indicator Yellow Cameleon 3.6. Using this protocol, we measured the calcium gradient in a large number of root hairs. We characterised their calcium oscillations and correlated them with the rate of hair growth. The method was then used to screen the effect of auxin on the properties of the growing root hairs.

  13. 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.

  14. Red-emitting fluorescent organic light emitting diodes with low sensitivity to self-quenching

    NASA Astrophysics Data System (ADS)

    Forget, S.; Chenais, S.; Tondelier, D.; Geffroy, B.; Gozhyk, I.; Lebental, M.; Ishow, E.

    2010-09-01

    Concentration quenching is a major impediment to efficient organic light-emitting devices (OLEDs). We herein report on OLEDs based on a fluorescent amorphous red-emitting starbust triarylamine molecule [4-di(4'-tert-butylbiphenyl-4-yl)amino-4'-dicyanovinylbenzene, named FVIN], exhibiting a very small sensitivity to concentration quenching. OLEDs are fabricated with various doping levels of FVIN into Alq3, and show a remarkably stable external quantum efficiency of 1.5% for doping rates ranging from 5% up to 40%, which strongly relaxes the technological constraints on the doping accuracy. An efficiency of 1% is obtained for a pure undoped active region, along with deep red emission (x=0.6; y=0.35 in the Commission Internationale de l'Energie (CIE) coordinates). A comparison of FVIN with the archetypal 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye is presented in an identical multilayer OLED structure.

  15. 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.

  16. Visualization of oxygen transfer across the air-water interface using a fluorescence oxygen visualization method.

    PubMed

    Lee, Minhee

    2002-04-01

    Oxygen concentration fields in a water body were visualized by the fluorescence oxygen visualization (FOV) method. Pyrenebutyric acid (PBA) was used as a fluorescent indicator of oxygen, and an intensive charge coupled-device (ICCD) camera as an image detector. Sequential images (over 2000 images) of the oxygen concentration field around the surface water of the tank (1 x 1 x 0.75 m3) were produced during the 3 h experiment. From image processing, the accurate pathway of oxygen-rich, cold water at the water surface was also visualized. The amount of oxygen transferred through the air-water interface during the experiment was measured and the oxygen transfer coefficient (K(L)) was determined as 0.22 m/d, which was much higher than that is expected in molecular diffusion. Results suggest that vertical penetration of cold water was the main pathway of oxygen in the water body in the tank. The average velocity of cold water penetrating downward in water body was also measured from consecutive images and the value was 0.3-0.6 mm/s. The FOV method used in this research should have wide application in experimental fluid mechanics and can also provide a phenomenological description of oxygen transfer under physically realizable natural conditions in lakes and reservoirs.

  17. 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%.

  18. Transitioning to Low-GWP Alternatives in Residential and Light Commercial Air Conditioning

    EPA Pesticide Factsheets

    This fact sheet provides current information on low global warming potential (GWP) alternatives for new equipment in residential and light commercial air conditioning (AC), in lieu of high-GWP hydrofluorocarbons (HFCs).

  19. 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

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

    PubMed

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

    2010-01-01

    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.

  1. 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).

  2. 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.

  3. 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.

  4. Analysis of Compact Fluorescent Lights for Use by Patients with Photosensitive Conditions

    PubMed Central

    Klein, Rachel S.; Werth, Victoria P.; Dowdy, John C.; Sayre, Robert M.

    2010-01-01

    Ultraviolet radiation (UVR) is hazardous to patients with photosensitive skin disorders, such as lupus erythematosus, xeroderma pigmentosum and skin cancer. As such, these patients are advised to minimize their exposure to UVR. Classically, this is accomplished through careful avoidance of sun exposure and artificial tanning booths. Indoor light bulbs, however, are generally not considered to pose significant UVR hazard. We sought to test this notion by measuring the UV emissions of 19 different compact fluorescent light bulbs. The ability to induce skin damage was assessed with the CIE erythema action spectrum, ANSI S(λ) generalized UV hazard spectrum and the CIE photocarcinogenesis action spectrum. The results indicate that there is a great deal of variation amongst different bulbs, even within the same class. Although the irradiance of any given bulb is low, the possible daily exposure time is rather lengthy. This results in potential daily UVR doses ranging from 0.1 to 625 mJ cm−2, including a daily UVB (290–320 nm) dose of 0.01 to 15 mJ cm−2. Because patients are exposed continually over long time frames, this could lead to significant cumulative damage. It would therefore be prudent for patients to use bulbs with the lowest UV irradiance. PMID:19320850

  5. Stripe artifact elimination based on nonsubsampled contourlet transform for light sheet fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Zang, Yali; Dong, Di; Zhang, Liwen; Fang, Mengjie; Yang, Xin; Arranz, Alicia; Ripoll, Jorge; Hui, Hui; Tian, Jie

    2016-10-01

    Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination light path, are a common drawback in both unidirectional and multidirectional light sheet fluorescence microscopy (LSFM), significantly deteriorating image quality. To circumvent this problem, we present an effective multidirectional stripe remover (MDSR) method based on nonsubsampled contourlet transform (NSCT), which can be used for both unidirectional and multidirectional LSFM. In MDSR, a fast Fourier transform (FFT) filter is designed in the NSCT domain to shrink the stripe components and eliminate the noise. Benefiting from the properties of being multiscale and multidirectional, MDSR succeeds in eliminating stripe artifacts in both unidirectional and multidirectional LSFM. To validate the method, MDSR has been tested on images from a custom-made unidirectional LSFM system and a commercial multidirectional LSFM system, clearly demonstrating that MDSR effectively removes most of the stripe artifacts. Moreover, we performed a comparative experiment with the variational stationary noise remover and the wavelet-FFT methods and quantitatively analyzed the results with a peak signal-to-noise ratio, showing an improved noise removal when using the MDSR method.

  6. Imaging of trabecular meshwork using Bessel–Gauss light sheet with fluorescence

    NASA Astrophysics Data System (ADS)

    Jie Jeesmond Hong, Xun; Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, Tin

    2017-03-01

    Ocular imaging technology that holds promise for both fundamental investigation and clinical detection of glaucoma is still a challenging research area. A direct view of the trabecular meshwork (TM) with high resolution is not generally possible because the iridocorneal angle region is obstructed by the sclera overlap. The best approach to observe the aqueous outflow system (AOS) is therefore to view from the opposite angle. In this research work, we developed two imaging systems for the high resolution ex vivo studies of the AOS inside porcine eye, based on a Gaussian illuminated and a digitally scanned Bessel–Gauss beam light sheet fluorescence configurations. The digitally scanned Bessel–Gauss beam is able to overcome the trade-off between the length and thickness of the Gaussian light sheet to give better imaging performance. It has adequate spatial resolution to resolve critical anatomical structures such as the TM, thereby enabling objective information about the AOS. This non-contact and non-invasive imaging methodology with excellent safety profile is expected to be well received by vision researchers and clinicians in the evaluation and management of glaucoma.

  7. Lighting up G protein-coupled purinergic receptors with engineered fluorescent ligands

    PubMed Central

    Ciruela, Francisco; Fernández-Dueñas, Víctor; Jacobson, Kenneth A.

    2015-01-01

    The use of G protein-coupled receptors fluorescent ligands is undergoing continuous expansion. In line with this, fluorescent agonists and antagonists of high affinity for G protein-coupled adenosine and P2Y receptors have been shown to be useful pharmacological probe compounds. Fluorescent ligands for A1R, A2AR, and A3R (adenosine receptors) and P2Y2R, P2Y4R, P2Y6R, and P2Y14R (nucleotide receptors) have been reported. Such ligands have been successfully applied to drug discovery and to GPCR characterization by flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer and scanning confocal microscopy. Here we summarize recently reported and readily available representative fluorescent ligands of purinergic receptors. In addition, we pay special attention on the use of this family of fluorescent ligands revealing two main aspects of purinergic receptor biology, namely ligand binding and receptor oligomerization. PMID:25890205

  8. 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.

  9. 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.

  10. 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...

  11. 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...

  12. 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

  13. 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

    2016-04-05

    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.

  14. AIRS First Light Data: Northern Europe, July 20, 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

    These images, taken over northern Europe on July 20, 2002, depict a few of the different views of Earth and its atmosphere that are produced by the Atmospheric Infrared Sounder experiment system operating on NASA's Aqua spacecraft.

    The image in Figure 1 is from an infrared channel from the AIRS instrument that measures the surface temperature in clear areas and cloud top temperatures in cloudy areas. The image reveals very warm conditions in France and a storm off the east coast of the United Kingdom.

    The image in Figure 2 represents a microwave channel from the Advanced Microwave Sounding Unit instrument that sees through most clouds and observes surface conditions everywhere.

    The image in Figure 3 is a microwave channel from the Humidity Sounder for Brazil instrument that is very sensitive to humidity and does not see the surface at all, but instead reveals the structure of moisture streams in the troposphere.

    The infrared and microwave data from the AIRS experiment are integrated to retrieve a single set of temperature, moisture, and cloud values. These three channels represent only a small portion of the 2,400-channel multispectral experiment, whose primary objectives are to improve the accuracy of weather forecasts and to study climate change.

    The AIRS experiment system also takes pictures of the Earth at four visible and near-infrared wavelengths that can be combined into a color picture. This image shows a swirling low-pressure system over England, clear skies over much of France, and frontal systems in the North Atlantic. Because AIRS is sensitive to different wavelengths than your eye, the colors shown are different from what you would see. For example, plants appear very red to AIRS. There are also subtle color differences in the clouds that relate to their altitude and thickness (compare the white

  15. 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.

  16. Field-induced control of universal fluorescence intermittency of a quantum dot light emitter

    NASA Astrophysics Data System (ADS)

    Lee, J. D.; Maenosono, S.

    2010-08-01

    With the nonstochastic quantum mechanical study of a quantum dot light emitter, we find that fluorescence intermittency statistics are universal and insensitive to the microscopic nature of the tunneling fluctuation between quantum dot and trapping state. We also investigate the power-law exponent θ and the crossover time τC of the on-time (τon) probability P(τon)∝τon-θ (for τon≲τC) and ∝e-Γτon (for τon≳τC) under an optical field of given energy and strength. For easy off-resonance excitation, it is found in both numerical and analytic ways that τC-1 is proportional to the intensity of the optical field (i.e., the square of the field strength) independent of the internal parameters of a quantum dot. Furthermore, it is also found that θ =2 in the limit of vanishing field strength is the upper bound of the exponent and θ becomes less than 2 as the field strength increases.

  17. Light induced fluorescence lidar developed and employed at the National Aviation Academy of Azerbaijan

    NASA Astrophysics Data System (ADS)

    Pashayev, Arif M.; Allahverdiyev, Kerim R.; Tagiyev, Bahadir G.; Sadikhov, Ilham A.

    2016-01-01

    A new laser induced fluorescence (LIF) KA-14 LIDAR (Light Identification Detection and Ranging) system for detecting of oil spills on the sea surface was developed and employed at the National Aviation Academy of Azerbaijan. Laser's parameters used in LIDAR are as follows: •laser CFR 200- type QUANTEL, λ = 355 nm, beam ∅ = 5.35 mm, f = 20 Hz, pulse duration and power τ = 7 ns and 60 mJ, respectively. The first results of measurements in the laboratory and the results of measurements at natural environment from distances up to 200 m revealed perspectives for using this LIDAR for detection of oil contaminations on sea as well as on earth surfaces (these measurements have been performed at Pirallahi Oil-Gas Production Company, Absheron peninsula, Baku, Azerbaijan). In the present work the results of emission spectra of crude oils taken from different regions of Absheron peninsula as well as the emission spectra of the oil spills on the surface of Caspian sea will be reported and discussed. These measurements open perspectives for using developed LIDAR for determination of place of oil-gas production company from which leakage takes place.

  18. Compact fluorescent lights and the impact of convenience and knowledge on household recycling rates.

    PubMed

    Wagner, Travis P

    2011-06-01

    Increased energy costs, social marketing campaigns, public subsidies, and reduced retail prices have dramatically increased the number of compact fluorescent lights (CFLs) installed worldwide. CFLs provide many benefits, but they contain a very small amount of mercury. Given the billions of CFLs in use worldwide, they represent a significant source of mercury unless CFLs are recycled and the mercury recovered in an environmentally sound manner. In the state of Maine (northeast United States), despite mandated recycling of CFLs and availability of free CFL recycling, the household CFL recycling rate is very low. A study was undertaken to identify the primary factors responsible for low recycling. The first step was to survey householders who use CFLs. The 520 survey responses indicated that insufficient knowledge regarding recycling and inconvenience of the collection system are the two primary factors for the low recycling rate. To validate these findings, the second step was an examination of the current collection system to assess (a) the knowledge requirements necessary for recycling and (b) the convenience of the collection system. The results of this examination validated that knowledge requirements were excessively difficult to fulfill and the collection system is not sufficiently convenient. Based on these results, waste managers should focus on increasing convenience and simplifying access to information when designing or improving household collection and recycling of CFLs.

  19. Photocatalytic bactericidal action of fluorescent light in a titanium dioxide particle mixture: an in vitro study.

    PubMed

    Koseki, Hironobu; Shiraishi, Koutaro; Asahara, Tomohiko; Tsurumoto, Toshiyuki; Shindo, Hiroyuki; Baba, Koumei; Taoda, Hiroshi; Terasaki, Nao

    2009-06-01

    Traditional titanium dioxide (TiO(2)) has photocatalytic bactericidal properties only under ultraviolet (UV) irradiation, which restricts its use in clinical treatment regimens. In this study, we evaluated the photocatalytic bactericidal effects of an aqueous system of TiO(2) particles irradiated by fluorescent light (FL) on Staphylococcus aureus. A TiO(2) particle mixture containing 19 ppm (0.019 mg/mL) of TiO(2) was prepared. A bacterial solution of 1 x 10(5) CFU/mL was added one drop at a time to the TiO(2) mixture. The resulting product was then irradiated with FL. The bacterial survival rate decreased steadily in the TiO(2) mixture group, reaching 76.7% after 30 min of FL irradiation and 10.9% after 60 min. After 60 to 180 min, the bacterial survival ratio of the TiO(2) mixture group was significantly lower than that of the control group (P < 0.05). The present study indicates that treating the surfaces of surgical devices and the surgical field with a TiO(2) particle mixture can create a nearly sterile environment that can be maintained throughout surgery, even at low luminous intensities.

  20. Effects of a Fluorescent Myosin Light Chain Phosphatase Inhibitor on Prostate Cancer Cells

    PubMed Central

    Grindrod, Scott; Suy, Simeng; Fallen, Shannon; Eto, Masumi; Toretsky, Jeffrey; Brown, Milton L.

    2011-01-01

    Myosin light chain phosphatase (MLCP) is an enzyme important to regulation of cell cycle and motility that is shown to be upregulated in aggressive prostate cancer cells and tissue. We developed a fluorescent small molecule inhibitor of MLCP using structure based design in recombinant protein phosphatase 1C. Several best fit compounds were synthesized and evaluated by their inhibition of MLCP/32P-MLC dephosphorylation, which resulted in the identification of novel MLCP inhibitors. Androgen dependent (AD) and castration resistant prostate cancer cell (CRPC) lines were treated with the lead inhibitor resulting in decreased growth rate, reduced DNA synthesis, and G2/M cell cycle arrest. Moreover, CRPC cell lines showed an increased sensitivity to drug treatment having GI50 values four times lower than the AD prostate cancer cell line. This was reinforced by reduced BrdU DNA incorporation into CRPC cells compared to AD cells. β-actin disruption was also seen at much lower drug concentrations in CR cells which caused a dose dependent reduction in cellular chemotaxis of PC-3 cells. Since there are currently few clinical therapeutics targeting CR prostate cancer, MLCP represents a new target for preclinical and clinical development of new potential therapeutics which inhibit this disease phenotype. PMID:22655237

  1. 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.

  2. [Theoretical study of fluorescence of photosynthetic pigments at complex dependence of intensity of exciting light on time].

    PubMed

    Alekseev, A A; Belov, A A; Kirzhanov, D V; Kukushkin, A K

    2012-01-01

    Now the methods using the radiance with complex dependence of light intensity on time are applied to research of photosynthesis by means of fluorescence, exciting photosynthetic pigments. One of these methods is applied in PAM-fluorometers--the commercial devices currently widely used to investigate a state of photosynthesizing systems. However, if excitation is performed in this way, the question, what components of fluorescence are registered at an output of such devices, remains to be open-ended. In this work an attempt to analyse this task has been made.

  3. 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.

  4. Acclimation of shade-tolerant and light-resistant Tradescantia species to growth light: chlorophyll a fluorescence, electron transport, and xanthophyll content.

    PubMed

    Mishanin, Vladimir I; Trubitsin, Boris V; Patsaeva, Svetlana V; Ptushenko, Vasily V; Solovchenko, Alexei E; Tikhonov, Alexander N

    2017-02-08

    In this study, we have compared the photosynthetic characteristics of two contrasting species of Tradescantia plants, T. fluminensis (shade-tolerant species), and T. sillamontana (light-resistant species), grown under the low light (LL, 50-125 µmol photons m(-2) s(-1)) or high light (HL, 875-1000 µmol photons m(-2) s(-1)) conditions during their entire growth period. For monitoring the functional state of photosynthetic apparatus (PSA), we measured chlorophyll (Chl) a emission fluorescence spectra and kinetics of light-induced changes in the heights of fluorescence peaks at 685 and 740 nm (F 685 and F 740). We also compared the light-induced oxidation of P700 and assayed the composition of carotenoids in Tradescantia leaves grown under the LL and HL conditions. The analyses of slow induction of Chl a fluorescence (SIF) uncovered different traits in the LL- and HL-grown plants of ecologically contrasting Tradescantia species, which may have potential ecophysiological significance with respect to their tolerance to HL stress. The fluorometry and EPR studies of induction events in chloroplasts in situ demonstrated that acclimation of both Tradescantia species to HL conditions promoted faster responses of their PSA as compared to LL-grown plants. Acclimation of both species to HL also caused marked changes in the leaf anatomy and carotenoid composition (an increase in Violaxanthin + Antheraxantin + Zeaxanthin and Lutein pools), suggesting enhanced photoprotective capacity of the carotenoids in the plants grown in nature under high irradiance. Collectively, the results of the present work suggest that the mechanisms of long-term PSA photoprotection in Tradescantia are based predominantly on the light-induced remodeling of pigment-protein complexes in chloroplasts.

  5. Detection of silver nanoparticles in cells by flow cytometry using light scatter and far-red fluorescence.

    PubMed

    Zucker, R M; Daniel, K M; Massaro, E J; Karafas, S J; Degn, L L; Boyes, W K

    2013-10-01

    The cellular uptake of different sized silver nanoparticles (AgNP) (10, 50, and 75 nm) coated with polyvinylpyrrolidone (PVP) or citrate on a human derived retinal pigment epithelial cell line (ARPE-19) was detected by flow cytometry following 24-h incubation of the cells with AgNP. A dose dependent increase of side scatter and far red fluorescence was observed with both PVP and citrate-coated 50 nm or 75 nm silver particles. Using five different flow cytometers, a far red fluorescence signal in the 700-800 nm range increased as much as 100 times background as a ratio comparing the intensity measurements of treated sample and controls. The citrate-coated silver nanoparticles (AgNP) revealed slightly more side scatter and far red fluorescence than did the PVP coated silver nanoparticles. This increased far red fluorescence signal was observed with 50 and 75 nm particles, but not with 10 nm particles. Morphological evaluation by dark field microscopy showed silver particles (50 and 75 nm) clumped and concentrated around the nucleus. One possible hypothesis to explain the emission of far red fluorescence from cells incubated with silver nanoparticles is that the silver nanoparticles inside cells agglomerate into small nano clusters that form surface plasmon resonance which interacts with laser light to emit a strong far red fluorescence signal. The results demonstrate that two different parameters (side scatter and far red fluorescence) on standard flow cytometers can be used to detect and observe metallic nanoparticles inside cells. The strength of the far red fluorescence suggests that it may be particularly useful for applications that require high sensitivity. © Published 2013 Wiley-Periodicals, Inc.

  6. 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

    2015-08-10

    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.

  7. A "turn-on" fluorescent sensor for ozone detection in ambient air using protein-directed gold nanoclusters.

    PubMed

    Wu, Di; Qi, Wenjing; Liu, Chun; Zhang, Qing

    2017-04-01

    A "turn-on" fluorescent sensor for ozone using bovine serum albumin-directed gold nanoclusters (BSA-Au NCs) via energy transfer was developed. The spectral overlap of fluorescent spectrum of BSA-Au NCs with absorption spectrum of indigo carmine (IDS) was utilized. Ozone cleaves C = C bond of IDS and suppresses energy transfer from BSA-Au NCs to IDS. Therefore, this proposed fluorescent sensor is a "turn-on" detection motif. It is the first application of fluorescent nanoclusters in sensitively detecting ozone from 0.2 to 12 μM with the limit of detection of 35 nM (the volume of 500 μL, 1.68 ppb). The proposed fluorescent sensor for ozone is more sensitive and faster (within 2 min) than most methods and is with good selectivity for ozone detection against other reactive oxygen species, reactive nitrogen, or metallic ions. Besides, the proposed method is also utlized in ozone detection in ambient air by monitoring 1 h (60 min) in Qijiang district in Chongqing city. The average of concentration of ozone in ambient air ranges from 44.97 to 52.85 μg/m(3). The results are compared with the automatic monitoring data provided by Qijiang Environmental Monitoring Station and the relative deviations range, respectively, from 2.1 to 5.6%, which suggests that it is a promising fluorescent sensor for ozone in ambient air. This study not only develops a new model of energy transfer motif using BSA-Au NCs as donor and IDS as acceptor but also expands the application of BSA-Au NCs in environmental science. Graphical abstract A "turn-on" fluorescent sensor for ozone detection using bovine serum albumin-directed gold nanoclusters (BSA-Au NCs) via energy transfer is developed. It is the first time to utilize spectral overlap of fluorescent spectrum of BSA-Au NCs with absorption spectrum of indigo carmine and to achieve fast, sensitive, and selective ozone detection with a limit of detection of down to 35 nM (the volume of 500 μL, 1.68 ppb).

  8. 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.

  9. Clinical comparison of the pharmacokinetics of m-THPC and Photofrin II as observed by light-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Braichotte, Daniel; Savary, Jean-Francois; Wagnieres, Georges A.; Mudry, A.; Fontolliet, Charlotte; Monnier, Philippe; van den Bergh, Hubert

    1994-01-01

    To optimize phototherapy and photodetection of cancer, one of the important variables is the localization of the dye after injection. To study this in a clinical context, we have constructed an apparatus based on a non-invasive optical fiber that detects the dye by light induced fluorescence. The time course of the fluorescence signal can be used directly for optimizing photodetection. However, complementary information on the detailed localization of the drug by fluorescence microscopy, and a correlation of this data with tumor necrosis efficacy, are necessary to optimize PDT timing. This will be demonstrated for the case of Photofrin II and tetra (meta- hydroxyphenyl) chlorin (mTHPC) and the two sets of data will be compared.

  10. 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.

  11. Observation of Brewster Angle Light Scattering from Air Bubbles Rising in Water

    DTIC Science & Technology

    1988-08-25

    At the bottom of this pipe a hollow needle is placed which is connected to an air supply. By regulating the air through the needle bubbles were...back scattering direction a beamsplitter was inserted in the light path. Then a retroreflector was placed behind the beamsplitter. The beam coming...out of the retroreflector is reflected at 45’ off the beamsplitter and then focused to a point. This point now defines the backwards direction. 03 0 t W

  12. 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

  13. Research of fluorescent spectra of oleic acid-stabilized ZnSe nanocrystals based on UV light modification

    NASA Astrophysics Data System (ADS)

    Hao, Licai; Bai, Zhongchen; Huang, Zhaoliang; Liao, Sha; Zhang, Zhengping

    2016-11-01

    The non-aqueous synthesized and post-preparative treatment of oleic acid (OA)-stabilized ZnSe nanocrystals were studied systematically. ZnSe nanocrystals were successfully synthesized via paraffin liquid and oleic acid system by using OA as stabilizer. Synthesized nanocrystals were characterized by means of absorption and fluorescent spectra, Fourier transform infrared spectrometer, transmission electron microscopy and selected area electron diffraction. Furthermore, solutions of ZnSe nanocrystals were illuminated with UV light. The experimental results showed that the fluorescent peak was red-shifted from 445 to 510 nm. The results suggested that, when the solution under illumination, OA was removed from the surface of ZnSe nanocrystals and the surface of ZnSe nanocrystals was oxidized to ZnO nanocrystals. ZnSe/ZnO core/shell nanocrystals were formed when the solution of ZnSe nanocrystals illuminated with UV light.

  14. Light-emitting diode fluorescence microscopy for tuberculosis diagnosis: a meta-analysis.

    PubMed

    Chang, Eva W; Page, Anne-Laure; Bonnet, Maryline

    2016-03-01

    Light-emitting diode fluorescence microscopy (LED-FM) is recommended by the World Health Organization to replace conventional Ziehl-Neelsen microscopy for pulmonary tuberculosis diagnosis. Uptake of LED-FM has been slow. One reason is its reported loss of specificity compared with Ziehl-Neelsen microscopy. We aimed to determine the diagnostic accuracy of LED-FM for tuberculosis detection and explore potential factors that might affect its performance.A comprehensive search strategy based on pre-specified criteria was employed to identify eligible studies between January 1, 2000 and April 1, 2014 in 11 databases. Standardised study selection, data extraction and quality assessment were conducted. Pooled sensitivity and specificity of LED-FM using culture as the reference standard were estimated through meta-analyses using a bivariate random-effects model. Investigation of heterogeneity was performed by subgroup analyses.We identified 12 unique studies, half of which were from peripheral healthcare facilities. LED-FM achieved a pooled sensitivity of 66.9% (95% CI 60.5-72.7%) and pooled specificity of 96.8% (95% CI 93.1-98.6%). A pooled sensitivity of 53.0% (95% CI 42.8-63.0%) and pooled specificity of 96.1% (95% CI 86.0-99.0%) were obtained by LED-FM among HIV-infected patients. Study methodology factors and differences in the LED-FM procedure or device could also affect the performance.LED-FM specificity is high and should not be a barrier to device introduction, particularly among peripheral healthcare settings where this technology is meant to be used. Sensitivity is reduced in HIV-infected patients.

  15. Relationships between human cataracts and environmental radiant energy. Cataract formation, light scattering and fluorescence.

    PubMed

    Zigman, S; Sutliff, G; Rounds, M

    1991-01-01

    This preliminary report has two parts. The first is based upon data obtained from a group of cataract patients in southern Florida (USA) with the object of relating the types of cataracts removed to their personal background and their protein biochemistry. Intra-capsular cataract surgery patients at the Venice Eye Clinic (Florida) were interviewed, and their extracted lenses were classified. The parameters were: age, place of residency, occupation, medical and family history and indoor/outdoor activity. Subcapsular cataracts were found mainly in the youngest patients and in those who were in Florida the least. Mixed cataracts predominated in the oldest patients, while non-nuclear cataracts were associated most with outdoor activity. Water-insoluble protein was elevated in nuclei of lenses with nuclear opacities. Soluble proteins in the nuclei of nuclear cataracts had increased levels of voided (heavy) protein, beta-crystallins, and less than 20 Kd peptides. The above changes were enhanced in brunescent cataracts. In lenses with cortical opacities, only increased size heterogeneity in the beta-crystallin region was observed. The second part of this report is based upon direct measurements of the optical properties of freshly extracted intra-capsular cataracts obtained in Rochester, New York (USA). The purpose was to attempt to learn the relative contributions that absorption, scattering, and fluorescence make toward obscuring vision. A general conclusion is that the shorter wavelengths of radiant energy in environmental lighting influence the above-stated optical properties the most, and thus appear to be the major contributors to obscured vision.

  16. Bimane: A Visible Light Induced Fluorescent Photoremovable Protecting Group for the Single and Dual Release of Carboxylic and Amino Acids.

    PubMed

    Chaudhuri, Amrita; Venkatesh, Yarra; Behara, Krishna Kalyani; Singh, N D Pradeep

    2017-03-10

    A series of ester conjugates of carboxylic and amino acids were synthesized based on bimane fluorescent photoremovable protecting group (FPRPG). The photorelease of single and dual (same as well as different) carboxylic and amino acids is demonstrated from a single bimane molecule on irradiation with visible light (λ ≥ 410 nm). The detailed mechanistic study of photorelease revealed that the release of two caged acids is simultaneous but in a stepwise pathway.

  17. Nanosecond ratio imaging of redox states in tumor cell spheroids using light sheet-based fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Schickinger, Sarah; Bruns, Thomas; Wittig, Rainer; Weber, Petra; Wagner, Michael; Schneckenburger, Herbert

    2013-12-01

    A new concept of three-dimensional imaging of tumor cell spheroids by light sheet-based fluorescence microscopy and nanosecond ratio imaging is described. Due to its low light dose and alternative excitation by two laser wavelengths (391 and 470 nm), this method maintains cell viability and permits recording of real-time kinetics. A genetically encoded sensor permits measurement of the redox state of glutathione and visualization of the impact of oxygen radicals. The pharmaceutically relevant system is tested upon addition of an oxidizing agent (H2O2), as well as upon addition of the apoptosis-inducing agent staurosporine.

  18. 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.

  19. Perturbation by UV Light for Rapid Classification of Biological Particles by Fluorescence

    DTIC Science & Technology

    2007-01-01

    27 5 FIGURES 1. Fluorescence of two isogenic Bacillus subtilis spore samples (DPA- and DPA+) before...Ex-Em graphs for E. coli grown overnight in rich medium ............................. 15 4. Bacillus thuringiensis spores ...from the chemical as a spore component. These were followed by studies of the Ex-Em graph of Bacillus subtilis spores of two types: The fluorescence Ex

  20. 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.

  1. LED-FISH: Fluorescence microscopy based on light emitting diodes for the molecular analysis of Her-2/neu oncogene amplification.

    PubMed

    Lang, Dagmar S; Zeiser, Tobias; Schultz, Holger; Stellmacher, Florian; Vollmer, Ekkehard; Zabel, Peter; Goldmann, Torsten

    2008-12-16

    Light emitting diodes (LED), which are available as small monochromatic light sources with characteristic features such as maximum illumination power combined with minimum energy consumption and extremely long lifespan have already proved as a highly potential low-cost alternative for specific diagnostic applications in clinical medicine such as tuberculosis fluorescence microscopy. Likewise, the most reliable evaluation of Her-2/neu (c-erbB2) gene amplification, which has been established in the last few years for routine diagnosis in clinical pathology as determinant towards Herceptin-based treatment of patients with breast cancer, is based on fluorescence in situ hybridization (FISH) and corresponding high priced fluorescence equipment. In order to test the possibility to utilize the advantages of low-cost LED technology on FISH analysis of c-erbB2 gene expression for routine diagnostic purposes, the applicability of a standard bright field Carl Zeiss Axiostar Plus microscope equipped with a Fraen AFTER (Amplified Fluorescence by Transmitted Excitation of Radiation) LED Fluorescence Microscope Kit for the detection of Her-2/neu gene signals was compared to an advanced Nikon Eclipse 80i fluorescence microscope in combination with a conventional 100W mercury vapor lamp. Both microscopes were fitted with the same Quicam FAST CCD digital camera to unequivocally compare the quality of the captured images. C-erbB2 gene expression was analyzed in 30 different human tissue samples of primary invasive breast cancer, following formalin fixation and subsequent paraffin-embedding. The Her2/neu gene signals (green) were identifiable in the tumor cells in all cases and images of equal quality were captured under almost identical conditions by 480 nm (blue) LED module equipped standard Axiostar microscope as compared to conventional fluorescence microscopy. In this first attempt, these monochromatic LED elements proved in principle to be suitable for the detection of Her-2/neu

  2. Nondestructive Evaluation (NDE) Exploratory Development for Air Force Systems. Delivery Order 0006: Paint Stripping Effects on Fluorescent Penetrant Inspection

    DTIC Science & Technology

    2009-12-01

    alloy were based upon the brightnesses of the pre-paint FPI indications; the objective was to have a similar distribution of brightness values in each...acetone. • Visually examine the specimens under both UV-A radiation and white light to verify that there is no residual fluorescent indication of any...6 4.5 Brightness Measurement of Penetrant Indications ...................................................................... 7 5. EDDY

  3. 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.

  4. Behavior of self-confined spherical layer of light radiation in the air atmosphere

    NASA Astrophysics Data System (ADS)

    Torchigin, V. P.; Torchigin, A. V.

    2004-07-01

    Behavior of thin spherical layer of intensive light in an inhomogeneous atmosphere is considered. It is shown that the behavior is similar to puzzling and mysterious behavior of ball lightnings. Under assumption that ball lightning moves along the gradient of atmosphere air density process of ball lightning penetration in a salon of a flying airplane is analyzed.

  5. 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.

  6. 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.

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

    PubMed

    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.

  8. 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

  9. Introduction of correlative light and airSEMTM microscopy imaging for tissue research under ambient conditions

    PubMed Central

    Solomonov, Inna; Talmi-Frank, Dalit; Milstein, Yonat; Addadi, Sefi; Aloshin, Anna; Sagi, Irit

    2014-01-01

    A complete fingerprint of a tissue sample requires a detailed description of its cellular and extracellular components while minimizing artifacts. We introduce the application of a novel scanning electron microscope (airSEMTM) in conjunction with light microscopy for functional analysis of tissue preparations at nanometric resolution (<10 nm) and under ambient conditions. Our metal-staining protocols enable easy and detailed visualization of tissues and their extracellular scaffolds. A multimodality imaging setup, featuring airSEMTM and a light microscope on the same platform, provides a convenient and easy-to-use system for obtaining structural and functional correlative data. The airSEMTM imaging station complements other existing imaging solutions and shows great potential for studies of complex biological systems. PMID:25100357

  10. Absorption and fluorescence spectroscopic characterisation of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry)

    NASA Astrophysics Data System (ADS)

    Shirdel, J.; Zirak, P.; Penzkofer, A.; Breitkreuz, H.; Wolf, E.

    2008-09-01

    The absorption and fluorescence behaviour of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry) in a pH 8 aqueous buffer solution is studied. The flavin adenine dinucleotide (FAD) cofactor of dCry is identified to be present in its oxidized form (FAD ox), and the 5,10-methenyltetrahydrofolate (MTHF) cofactor is found to be hydrolyzed and oxidized to 10-formyldihydrofolate (10-FDHF). The absorption and the fluorescence behaviour of dCry is investigated in the dark-adapted (receptor) state, the light-adapted (signalling) state, and under long-time violet light exposure. Photo-excitation of FAD ox in dCry causes a reductive electron transfer to the formation of anionic FAD semiquinone (FAD rad - ), and photo-excitation of the generated FAD rad - causes an oxidative electron transfer to the back formation of FAD ox. In light adapted dCry a photo-induced equilibrium between FAD ox and FAD rad - exists. The photo-cycle dynamics of signalling state formation and recovery is discussed. Quantum yields of photo-induced signalling state formation of about 0.2 and of photo-induced back-conversion of about 0.2 are determined. A recovery of FAD rad - to FAD ox in the dark with a time constant of 1.6 min at room temperature is found.

  11. Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission

    PubMed Central

    Escombe, A. Roderick; Moore, David A. J; Gilman, Robert H; Navincopa, Marcos; Ticona, Eduardo; Mitchell, Bailey; Noakes, Catherine; Martínez, Carlos; Sheen, Patricia; Ramirez, Rocio; Quino, Willi; Gonzalez, Armando; Friedland, Jon S; Evans, Carlton A

    2009-01-01

    Background Institutional tuberculosis (TB) transmission is an important public health problem highlighted by the HIV/AIDS pandemic and the emergence of multidrug- and extensively drug-resistant TB. Effective TB infection control measures are urgently needed. We evaluated the efficacy of upper-room ultraviolet (UV) lights and negative air ionization for preventing airborne TB transmission using a guinea pig air-sampling model to measure the TB infectiousness of ward air. Methods and Findings For 535 consecutive days, exhaust air from an HIV-TB ward in Lima, Perú, was passed through three guinea pig air-sampling enclosures each housing approximately 150 guinea pigs, using a 2-d cycle. On UV-off days, ward air passed in parallel through a control animal enclosure and a similar enclosure containing negative ionizers. On UV-on days, UV lights and mixing fans were turned on in the ward, and a third animal enclosure alone received ward air. TB infection in guinea pigs was defined by monthly tuberculin skin tests. All guinea pigs underwent autopsy to test for TB disease, defined by characteristic autopsy changes or by the culture of Mycobacterium tuberculosis from organs. 35% (106/304) of guinea pigs in the control group developed TB infection, and this was reduced to 14% (43/303) by ionizers, and to 9.5% (29/307) by UV lights (both p < 0.0001 compared with the control group). TB disease was confirmed in 8.6% (26/304) of control group animals, and this was reduced to 4.3% (13/303) by ionizers, and to 3.6% (11/307) by UV lights (both p < 0.03 compared with the control group). Time-to-event analysis demonstrated that TB infection was prevented by ionizers (log-rank 27; p < 0.0001) and by UV lights (log-rank 46; p < 0.0001). Time-to-event analysis also demonstrated that TB disease was prevented by ionizers (log-rank 3.7; p = 0.055) and by UV lights (log-rank 5.4; p = 0.02). An alternative analysis using an airborne infection model demonstrated that ionizers prevented 60% of

  12. 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

  13. 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 ...

  14. 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

  15. Quasi-continuous combined scattered light and fluorescence measurements: a novel measurement technique for shaken microtiter plates.

    PubMed

    Samorski, M; Müller-Newen, G; Büchs, J

    2005-10-05

    A novel quasi-continuous on-line measuring technique for shaken microtiter plates is presented. Light scattering as well as intracellular and/or protein fluorescence (e.g. NADH, YFP) is measured during the shaking procedure, thus allowing a process monitoring of 96 different simultaneous cultures in a microtiter plate. In contrast to existing measurement techniques, the shaking process does not have to be stopped to take the measurements, thus avoiding the corresponding interruption of the cultures' oxygen supply and any unpredictable effects on the cultures. Experiments were conducted with E. coli in LB, TB, and MOPS minimal medium and V. natriegens in modified LB and TB media. Intensity curves of scattered light and NADH fluorescence were used to distinguish different lag phases, growth velocities, or inoculation densities. Data from this new method corresponded well to the off-line measured optical densities and to the oxygen transfer rates of cultures run in simultaneously conducted shake flask experiments at equivalent oxygen transfer capacities. With the aid of yellow fluorescence protein fused to interleukin-6 the optimal induction time of an expressing E. coli strain could be determined by on-line monitoring of product formation. Thus, this measuring technique enables the researcher to evaluate and to discriminate different cultures on a screening level and to improve screening conditions, process development and scale-up.

  16. 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.

  17. Fluorescence imaging of microbe-containing particles shot from a two-stage Light-gas gun into an aerogel

    NASA Astrophysics Data System (ADS)

    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.

  18. Integrated fluorescence detection of labeled biomolecules using a prism-like PDMS microfluidic chip and lateral light excitation.

    PubMed

    Novo, Pedro; Chu, Virginia; Conde, João Pedro

    2014-06-21

    Microfabricated amorphous silicon photodiodes were integrated with prism-like PDMS microfluidics for the detection and quantification of fluorescence signals. The PDMS device was fabricated with optical quality surfaces and beveled sides. A 405 nm laser beam perpendicular to the lateral sides of the microfluidic device excites the fluorophores in the microchannel at an angle of 70° to the normal to the microchannel/photodiode surface. This configuration, which makes use of the total internal reflection of the excitation beam and the isotropy of the fluorescence emission, minimizes the intensity of excitation light that reaches the integrated photodetector. A difference of two orders of magnitude was achieved in the reduction of the detection noise level as compared with a normally incident excitation configuration. A limit-of-detection of 5.6 × 10(10) antibodies per square centimeter was achieved using antibodies labeled with a model organic fluorophore. Furthermore, the results using the lateral excitation scheme are in good proportionality agreement with those by fluorescence quantification using wide-field fluorescence microscopy.

  19. 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

  20. 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.

  1. Integrated Fluorescence

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret (Inventor); Gruhlke, Russell W. (Inventor)

    1998-01-01

    A detection method is integrated with a filtering method and an enhancement method to create a fluorescence sensor that can be miniaturized. The fluorescence sensor comprises a thin film geometry including a waveguide layer, a metal film layer and sensor layer. The thin film geometry of the fluorescence sensor allows the detection of fluorescent radiation over a narrow wavelength interval. This enables wavelength discrimination and eliminates the detection of unwanted light from unknown or spurious sources.

  2. 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.

  3. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  4. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  5. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  6. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  7. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  8. Development of an integrated direct-contacting optical-fiber microchip with light-emitting diode-induced fluorescence detection.

    PubMed

    Liu, Changchun; Cui, Dafu; Chen, Xing

    2007-11-02

    In this paper, one poly(dimethylsiloxane) (PDMS) sandwich microchip integrated with one direct-contacting optical fiber was fabricated by using a thin-casting method. This novel integrated PDMS sandwich microchip included top glass plate, PDMS membrane replica with microfluidic networks and optical fiber, flat PDMS membrane and bottom glass plate. As the tip of excitation optical fiber completely contacted with the separation microchannel in this integrated microchip, it not only increased the excitation light intensity to achieve the high sensitivity, but also reduced the diameter of excitation beam to obtain high resolution. In addition, we found that this rigid PDMS sandwich microchip structure effectively prevented PDMS microchannel distortion from rigid optical fiber, and provided a substantial convenience for microchips manipulating. A blue light-emitting diode (LED) was applied as excitation source by using optical fiber to couple excitation light into its direct-contacting microchannel for fluorescence detection. The performances of this integrated PDMS sandwich microchip was demonstrated by separating the mixture of sodium fluorescein (SF) and fluorescein isothiocyanate isomer I (FITC), and showed a higher sensitive and resolution than those obtained from the conventional integrated optical-fiber PDMS microchip with a 100-microm distance between fiber tip and separation microchannel. Additionally, the reproducibility of this integrated microchip with LED-induced fluorescence detection was also examined by separation of a mixture of FITC-labeled amino acids.

  9. The mechanism of light emission from a scanning tunnelling microscope operating in air

    NASA Astrophysics Data System (ADS)

    Rogez, B.; Cao, S.; Dujardin, G.; Comtet, G.; Le Moal, E.; Mayne, A.; Boer-Duchemin, E.

    2016-11-01

    The scanning tunnelling microscope (STM) may be used as a low-energy, electrical nanosource of surface plasmon polaritons and light. In this article, we demonstrate that the optimum mode of operation of the STM for maximum photon emission is completely different in air than in vacuum. To this end, we investigate the emission of photons, the variation in the relative tip-sample distance and the measured current as a function of time for an STM operating in air. Contrary to the case of an STM operating in vacuum, the measured current between the tip and sample for an STM in air is very unstable (rapidly fluctuating in time) when the applied voltage between the tip and sample is in the ˜1.5-3 V range (i.e., in the energy range of visible photons). The photon emission occurs in short (50 μs) bursts when the STM tip is closest to the sample. The current instabilities are shown to be a key ingredient for producing intense light emission from an STM operating in air (photon emission rate several orders of magnitude higher than for stable current). These results are explained in terms of the interplay between the tunnel current and the electrochemical current in the ubiquitous thin water layer that exists when working in air.

  10. "DNA Origami Traffic Lights" with a Split Aptamer Sensor for a Bicolor Fluorescence Readout.

    PubMed

    Walter, Heidi-Kristin; Bauer, Jens; Steinmeyer, Jeannine; Kuzuya, Akinori; Niemeyer, Christof M; Wagenknecht, Hans-Achim

    2017-04-12

    A split aptamer for adenosine triphosphate (ATP) was embedded as a recognition unit into two levers of a nanomechanical DNA origami construct by extension and modification of selected staple strands. An additional optical module in the stem of the split aptamer comprised two different cyanine-styryl dyes that underwent an energy transfer from green (donor) to red (acceptor) emission if two ATP molecules were bound as target molecule to the recognition module and thereby brought the dyes in close proximity. As a result, the ATP as a target triggered the DNA origami shape transition and yielded a fluorescence color change from green to red as readout. Conventional atomic force microscopy (AFM) images confirmed the topology change from the open form of the DNA origami in the absence of ATP into the closed form in the presence of the target molecule. The obtained closed/open ratios in the absence and presence of target molecules tracked well with the fluorescence color ratios and thereby validated the bicolor fluorescence readout. The correct positioning of the split aptamer as the functional unit farthest away from the fulcrum of the DNA origami was crucial for the aptasensing by fluorescence readout. The fluorescence color change allowed additionally to follow the topology change of the DNA origami aptasensor in real time in solution. The concepts of fluorescence energy transfer for bicolor readout in a split aptamer in solution, and AFM on surfaces, were successfully combined in a single DNA origami construct to obtain a bimodal readout. These results are important for future custom DNA devices for chemical-biological and bioanalytical purposes because they are not only working as simple aptamers but are also visible by AFM on the single-molecule level.

  11. 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.

  12. 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

  13. Effect of Different Light Qualities on Growth, Pigment Content, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in the Red Alga Pyropia haitanensis (Bangiales, Rhodophyta).

    PubMed

    Wu, Huanyang

    2016-01-01

    Spectral light changes evoke different morphogenetic and photosynthetic responses that can vary among different algae species. The aim of this study is to investigate the photosynthetic characteristics of the red macroalgae grown under different spectrum environments. In this study, Pyropia haitanensis were cultured under blue, red, and green LED and fluorescent tubes light. The growth rate, photopigment composition, chlorophyll fluorescence, and antioxidative enzymes activities in different light spectrums were investigated. The results revealed that growth rate was significantly higher in the thalli grown under blue, green, and fluorescent tubes light. Contents of Chl a and phycobiliprotein in red light were lower among all the growth conditions. Furthermore, a striking increase in SOD and CAT activity was observed in red light treatment along with the NPQ increase. The results revealed that the photosynthetic efficiency and increased growth rate of P. haitanensis benefitted from light spectrums such as blue, green, and fluorescent tubes light by pigment composition and photochemical efficiency manipulation, whereas red light has disadvantageous effects. Accordingly, the results for improving quality and the economic yield of algae species in some extent and the combination of different wavelengths could allow better economic resource exploitation.

  14. Effect of Different Light Qualities on Growth, Pigment Content, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in the Red Alga Pyropia haitanensis (Bangiales, Rhodophyta)

    PubMed Central

    2016-01-01

    Spectral light changes evoke different morphogenetic and photosynthetic responses that can vary among different algae species. The aim of this study is to investigate the photosynthetic characteristics of the red macroalgae grown under different spectrum environments. In this study, Pyropia haitanensis were cultured under blue, red, and green LED and fluorescent tubes light. The growth rate, photopigment composition, chlorophyll fluorescence, and antioxidative enzymes activities in different light spectrums were investigated. The results revealed that growth rate was significantly higher in the thalli grown under blue, green, and fluorescent tubes light. Contents of Chl a and phycobiliprotein in red light were lower among all the growth conditions. Furthermore, a striking increase in SOD and CAT activity was observed in red light treatment along with the NPQ increase. The results revealed that the photosynthetic efficiency and increased growth rate of P. haitanensis benefitted from light spectrums such as blue, green, and fluorescent tubes light by pigment composition and photochemical efficiency manipulation, whereas red light has disadvantageous effects. Accordingly, the results for improving quality and the economic yield of algae species in some extent and the combination of different wavelengths could allow better economic resource exploitation. PMID:27642603

  15. 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

  16. 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

  17. Fluorescent proteins as biomarkers and biosensors: throwing color lights on molecular and cellular processes.

    PubMed

    Stepanenko, Olesya V; Verkhusha, Vladislav V; Kuznetsova, Irina M; Uversky, Vladimir N; Turoverov, K K

    2008-08-01

    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.

  18. Recording of individual identification information on dental prostheses using fluorescent material and ultraviolet light.

    PubMed

    Naito, Yoshihito; Meinar, Ashrin N; Iwawaki, Yuki; Kashiwabara, Toshiya; Goto, Takaharu; Ito, Teruaki; Sakuma, Tetsuro; Ichikawa, Tetsuo

    2013-01-01

    The placement of individual identification on a prosthesis is very important for forensic dentistry and traceability. This article describes the unique naming/labeling of dentures with information for individual identification using a method in which information is invisible under natural light but visible under ultraviolet light-emitting diode/black light exposure. The use of laser beam machining with this method will enable the recording of a large amount of information.

  19. Promising operational stability of high-efficiency organic light-emitting diodes based on thermally activated delayed fluorescence

    PubMed Central

    Nakanotani, Hajime; Masui, Kensuke; Nishide, Junichi; Shibata, Takumi; Adachi, Chihaya

    2013-01-01

    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. PMID:23820465

  20. 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.

  1. 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.

  2. 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.

  3. A Fluorescence Light-Up Ag Nanocluster Probe that Discriminates Single-Nucleotide Variants by Emission Color

    PubMed Central

    Yeh, Hsin-Chih; Sharma, Jaswinder; Shih, Ie-Ming; Vu, Dung M.; Martinez, Jennifer S.; Werner, James H.

    2012-01-01

    Rapid and precise screening of small genetic variations, such as single-nucleotide polymorphisms (SNPs), among an individual’s genome is still an unmet challenge at point-of-care settings. One crucial step towards this goal is the development of discrimination probes that require no enzymatic reaction and are easy to use. Here we report a new type of fluorescent molecular probe, termed a chameleon NanoCluster Beacon (cNCB), that lights up into different colors upon binding SNP targets. NanoCluster Beacons (NCBs) are collections of a small number of Ag atoms templated on single-stranded DNA that fluoresce strongly when placed in proximity to particular DNA sequences, termed enhancers. Here we show the fluorescence emission color of a NCB can change substantially (a shift of 60–70 nm in the emission maximum) depending upon the alignment between the silver nanocluster and the DNA enhancer sequence. Chameleon NCBs exploit this color shift to directly detect SNPs, based on the fact that different SNPs produce a different alignment between the Ag nanocluster and the enhancer. This SNP detection method has been validated on all single-nucleotide substitution scenarios in three synthetic DNA targets, in six disease-related SNP targets, and in two clinical samples taken from patients with ovarian serous borderline tumors. Samples with single-nucleotide variations can be easily identified by the naked eye under UV excitation, making this method a reliable and low-cost assay with a simple readout format. PMID:22775452

  4. A fluorescence light-up Ag nanocluster probe that discriminates single-nucleotide variants by emission color.

    PubMed

    Yeh, Hsin-Chih; Sharma, Jaswinder; Shih, Ie-Ming; Vu, Dung M; Martinez, Jennifer S; Werner, James H

    2012-07-18

    Rapid and precise screening of small genetic variations, such as single-nucleotide polymorphisms (SNPs), among an individual's genome is still an unmet challenge at point-of-care settings. One crucial step toward this goal is the development of discrimination probes that require no enzymatic reaction and are easy to use. Here we report a new type of fluorescent molecular probe, termed a chameleon NanoCluster Beacon (cNCB), that lights up into different colors upon binding SNP targets. NanoCluster Beacons (NCBs) are collections of a small number of Ag atoms templated on single-stranded DNA that fluoresce strongly when placed in proximity to particular DNA sequences, termed enhancers. Here we show the fluorescence emission color of a NCB can change substantially (a shift of 60-70 nm in the emission maximum) depending upon the alignment between the silver nanocluster and the DNA enhancer sequence. Chameleon NCBs exploit this color shift to directly detect SNPs, based on the fact that different SNPs produce a different alignment between the Ag nanocluster and the enhancer. This SNP detection method has been validated on all single-nucleotide substitution scenarios in three synthetic DNA targets, in six disease-related SNP targets, and in two clinical samples taken from patients with ovarian serous borderline tumors. Samples with single-nucleotide variations can be easily identified by the naked eye under UV excitation, making this method a reliable and low-cost assay with a simple readout format.

  5. 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.

  6. 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

  7. Design of chlorophyll-a and turbidity sensor based on fluorescence induction and scattering-light detection

    NASA Astrophysics Data System (ADS)

    Zhang, Keke; Liu, Shixuan; Chen, Shizhe; Qi, Yong; Miao, Bin; Yan, Xingkui; Bai, Xuejiao

    2014-07-01

    The chlorophyll-a and turbidity sensor based on the principles of fluorescence induction and scattering-light detection is designed. Using fluorescence induction technology, scattering-light detection technology and weak signal detection technology, chlorophyll-a concentration measurement and turbidity measurement in seawater are integrated in a set of testing equipment to implement software and hardware reuse and improve the integration of the device, which has the features of small size and easy operation. The comparative experiments and repetitive experiments are completed with ALEC ACLW-CAR chlorophyll / turbidity sensor. Experiment results show that chlorophyll-a concentration, turbidity and the system output values have good linear relationships, and the fitting coefficients are 0.999. Repeatability standard deviations of chlorophyll-a detection and turbidity detection are better than 0.08 μg/L and 0.04 FTU, respectively, and the accuracy of the device within +/- 2%. Chlorophyll-a and turbidity in-situ monitoring in seawater can be achieved using this testing equipment.

  8. 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.

  9. Tea quality and classification evaluation using multi-wavelength light-emitting diodes induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Liu, Xuan; Yan, Chunsheng; He, Sailing; Mei, Liang

    2013-03-01

    In this paper, we demonstrated a detective system to evaluate the quality and classification of different tea samples based on multi-wavelength LED-induced fluorescence spectroscopy. By utilizing multiple excitation wavelengths, we obtained much more physical and chemical information from the detected samples than single excitation wavelength. By utilizing principal component analysis (PCA), we extracted the dominant features of the samples to classify and characterize the tea samples.

  10. 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.

  11. 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.

  12. Pulsed lasers versus continuous light sources in capillary electrophoresis and fluorescence detection studies: Photodegradation pathways and models.

    PubMed

    Boutonnet, Audrey; Morin, Arnaud; Petit, Pierre; Vicendo, Patricia; Poinsot, Véréna; Couderc, François

    2016-03-17

    Pulsed lasers are widely used in capillary electrophoresis (CE) studies to provide laser induced fluorescence (LIF) detection. Unfortunately pulsed lasers do not give linear calibration curves over a wide range of concentrations. While this does not prevent their use in CE/LIF studies, the non-linear behavior must be understood. Using 7-hydroxycoumarin (7-HC) (10-5000 nM), Tamra (10-5000 nM) and tryptophan (1-200 μM) as dyes, we observe that continuous lasers and LEDs result in linear calibration curves, while pulsed lasers give polynomial ones. The effect is seen with both visible light (530 nm) and with UV light (355 nm, 266 nm). In this work we point out the formation of byproducts induced by pulsed laser upon irradiation of 7-HC. Their separation by CE using two Zeta LIF detectors clearly shows that this process is related to the first laser detection. All of these photodegradation products can be identified by an ESI-/MS investigation and correspond to at least two 7HC dimers. By using the photodegradation model proposed by Heywood and Farnsworth (2010) and by taking into account the 7-HC results and the fact that in our system we do not have a constant concentration of fluorophore, it is possible to propose a new photochemical model of fluorescence in LIF detection. The model, like the experiment, shows that it is difficult to obtain linear quantitation curves with pulsed lasers while UV-LEDs used in continuous mode have this advantage. They are a good alternative to UV pulsed lasers. An application involving the separation and linear quantification of oligosaccharides labeled with 2-aminobezoic acid is presented using HILIC and LED (365 nm) induced fluorescence.

  13. 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.

  14. 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.

  15. Adaptation of photosystem II to high and low light in wild-type and triazine-resistant Canola plants: analysis by a fluorescence induction algorithm.

    PubMed

    van Rensen, Jack J S; Vredenberg, Wim J

    2011-09-01

    Plants of wild-type and triazine-resistant Canola (Brassica napus L.) were exposed to very high light intensities and after 1 day placed on a laboratory table at low light to recover, to study the kinetics of variable fluorescence after light, and after dark-adaptation. This cycle was repeated several times. The fast OJIP fluorescence rise curve was measured immediately after light exposure and after recovery during 1 day in laboratory room light. A fluorescence induction algorithm has been used for resolution and analysis of these curves. This algorithm includes photochemical and photo-electrochemical quenching release components and a photo-electrical dependent IP-component. The analysis revealed a substantial suppression of the photo-electrochemical component (even complete in the resistant biotype), a partial suppression of the photochemical component and a decrease in the fluorescence parameter F (o) after high light. These effects were recovered after 1 day in the indoor light.

  16. An analytical approach to the multiply scattered light in the optical images of the extensive air showers of ultra-high energies

    NASA Astrophysics Data System (ADS)

    Giller, Maria; Śmiałkowski, Andrzej

    2012-08-01

    One of the methods for studying the highest energy cosmic rays is to measure the fluorescence light emitted by the extensive air showers induced by them. To reconstruct a shower cascade curve from measurements of the number of photons arriving from the subsequent shower track elements it is necessary to take into account the multiple scatterings that photons undergo on their way from the shower to the detector. In contrast to the earlier Monte-Carlo work, we present here an analytical method to treat the Rayleigh and Mie scatterings in the atmosphere. The method consists in considering separately the consecutive 'generations' of the scattered light. Starting with a point light source in a uniform medium, we then examine a source in a real atmosphere and finally - a moving source (shower) in it. We calculate the angular distributions of the scattered light superimposed on the not scattered light registered from a shower at a given time. The analytical solutions (although approximate) show how the exact numerical results should be parametrised what we do for the first two generations (the contribution of the higher ones being small). Not allowing for the considered effect may lead to an overestimation of shower primary energy by ˜15% and to an underestimation of the primary particle mass (E0=1019eV with the core distance 25 km and θZ=40°).

  17. Interactions of hypericin with a model mutagen - Acridine orange analyzed by light absorption and fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Pietrzak, Monika; Szabelski, Mariusz; Kasparek, Adam; Wieczorek, Zbigniew

    2017-02-01

    The present study was designed to estimate the ability of hypericin to interact with a model mutagen - acridine orange. The hetero-association of hypericin and acridine orange was investigated with absorption and fluorescence spectroscopy methods in aqueous solution of DMSO. The data indicate that hypericin forms complexes with acridine orange and that the association constants are relatively high and depend on DMSO concentration. The absorption spectra of the hypericin - acridine orange complexes were examined as well. Owing to its ability to interact with flat aromatic compounds, hypericin may potentially be used as an interceptor molecule.

  18. Indication of transthylakoid proton-fluxes in Aegopodium podagraria L. by light-induced changes of plasmalemma potential, chlorophyll fluorescence and light-scattering.

    PubMed

    Vanselow, K H; Dau, H; Hansen, U P

    1988-12-01

    The time course of the responses of chlorophyll fluorescence in leaves of Aegopodium podagraria to changes in irradiance does not necessarily show the time constant of thylakoid energization at energy fluence rates below 10-25 W·m(-2). In addition, other measures of thylakoid energization, such as lightscattering at 532 nm and the responses to saturating flashes, show that the related component disappears from these signals at low fluence rates, but not necessarily all together at the same fluence rate. However, this time constant still appears in the light-induced responses of the plasmalemma potential. This implies that the effect on the electrogenic proton pump in the plasmalemma is the most sensitive indicator of proton fluxes into the inner thylakoid space. These results are a further indication that energy-quenching is coupled ther indication that energy-quenching is coupled to transthylakoid proton fluxes via an intermediate, which is not active in Aegopodium podagraria at low irradiances.

  19. 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

  20. New light on ion channel imaging by total internal reflection fluorescence (TIRF) microscopy.

    PubMed

    Yamamura, Hisao; Suzuki, Yoshiaki; Imaizumi, Yuji

    2015-05-01

    Ion channels play pivotal roles in a wide variety of cellular functions; therefore, their physiological characteristics, pharmacological responses, and molecular structures have been extensively investigated. However, the mobility of an ion channel itself in the cell membrane has not been examined in as much detail. A total internal reflection fluorescence (TIRF) microscope allows fluorophores to be imaged in a restricted region within an evanescent field of less than 200 nm from the interface of the coverslip and plasma membrane in living cells. Thus the TIRF microscope is useful for selectively visualizing the plasmalemmal surface and subplasmalemmal zone. In this review, we focused on a single-molecule analysis of the dynamic movement of ion channels in the plasma membrane using TIRF microscopy. We also described two single-molecule imaging techniques under TIRF microscopy: fluorescence resonance energy transfer (FRET) for the identification of molecules that interact with ion channels, and subunit counting for the determination of subunit stoichiometry in a functional channel. TIRF imaging can also be used to analyze spatiotemporal Ca(2+) events in the subplasmalemma. Single-molecule analyses of ion channels and localized Ca(2+) signals based on TIRF imaging provide beneficial pharmacological and physiological information concerning the functions of ion channels.

  1. Air-Stable flexible organic light-emitting diodes enabled by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Lin, Yuan-Yu; Chang, Yi-Neng; Tseng, Ming-Hung; Wang, Ching-Chiun; Tsai, Feng-Yu

    2015-01-01

    Organic light-emitting diodes (OLED) are an energy-efficient light source with many desirable attributes, besides being an important display of technology, but its practical application has been limited by its low air-stability. This study demonstrates air-stable flexible OLEDs by utilizing two atomic-layer-deposited (ALD) films: (1) a ZnO film as both a stable electron-injection layer (EIL) and as a gas barrier in plastics-based OLED devices, and (2) an Al2O3/ZnO (AZO) nano-laminated film for encapsulating the devices. Through analyses of the morphology and electrical/gas-permeation properties of the films, we determined that a low ALD temperature of 70 °C resulted in optimal EIL performance from the ZnO film and excellent gas-barrier properties [water vapor transmission rate (WVTR) <5 × 10-4 g m-2 day-1] from both the ZnO EIL and the AZO encapsulating film. The low-temperature ALD processes eliminated thermal damage to the OLED devices, which were severe when a 90 °C encapsulation process was used, while enabling them to achieve an air-storage lifetime of >10 000 h.

  2. Water permeability through biological membranes by isotopic effects of fluorescence and light scattering.

    PubMed Central

    Lawaczeck, R

    1984-01-01

    A light-scattering technique used to measure the water permeability across closed biomembranes is described, which is based on the different indices of refraction of D2O and H2O. This transient technique is compared with a similar method using D2O-sensitive fluorophores in the intravesicular space. The results of both techniques are equivalent although the signal-to-noise ratio favors the light-scattering or turbidity experiment. The light-scattering method is only applicable to larger particles (no point-scatterers) and is easily extended to biological objects. Data on the H2O/D2O exchange across membranes of ghosts from human erythrocytes suggest two mechanisms: the D2O and H2O permeation through the membrane and a slower D2O-induced conformational change of membraneous proteins. PMID:6546887

  3. 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.

  4. 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.

  5. 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 ...

  6. Quenching of chlorophyll fluorescence in the major light-harvesting complex of photosystem II: a systematic study of the effect of carotenoid structure.

    PubMed Central

    Phillip, D; Ruban, A V; Horton, P; Asato, A; Young, A J

    1996-01-01

    The role of carotenoids in quenching of chlorophyll fluorescence in the major light-harvesting complex of photosystem II has been studied with a view to understanding the molecular basis of the control of photoprotective nonradiative energy dissipation by the xanthophyll cycle in vivo. The control of chlorophyll fluorescence quenching in the isolated complex has been investigated in terms of the number of the conjugated double bonds for a series of carotenoids ranging from n = 5-19, giving an estimated first excited singlet state energy from 20,700 cm-1 to 10,120 cm-1. At pH 7.8 the addition of exogenous carotenoids with >=10 conjugated double bonds (including zeaxanthin) stimulated fluorescence quenching relative to the control with no added carotenoid, whereas those with n fluorescence. When quenching in the light-harvesting complex of photosystem II was induced by a lowering of pH to 5.5, carotenoids with n fluorescence quenching relative to the control. Of the 10 carotenoids tested, quenching induced by the addition of the tertiary amine compound, dibucaine, to isolated light-harvesting complex of photosystem II could only be reversed by violaxanthin. These results are discussed in terms of the two theories developed to explain the role of zeaxanthin and violaxanthin in nonphotochemical quenching of chlorophyll fluorescence. PMID:11607629

  7. Ultraviolet-visible light (UV-Vis)-reversible but fluorescence-irreversible chemosensor for copper in water and its application in living cells.

    PubMed

    Huo, Fang-Jun; Yin, Cai-Xia; Yang, Yu-Tao; Su, Jing; Chao, Jian-Bin; Liu, Dian-Sheng

    2012-03-06

    An ultraviolet-visible light (UV-Vis)-reversible but fluorescence-irreversible chemosensor was developed for the detection of copper. Coordination between the probe, 2-pyridylaldehyde fluorescein hydrazone (FHP), and Cu(2+) gave a reversible UV-Vis response, Storage of the probe-Cu complex resulted in hydrolytic cleavage of the N═C bond, which released the fluorophore (ring-opened fluorescein hydrazine) and gave irreversible fluorescence. Thus, FHP becomes a multifunctional chemosensor, and its reversibility can be controlled by the reaction time. Cu(2+) in living cells could be detected using FHP and general fluorescence methods.

  8. 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

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. Aggregation and fluorescence quenching of chlorophyll a of the light-harvesting complex II from spinach in vitro.

    PubMed

    Kirchhoff, Helmut; Hinz, Hans-Jürgen; Rösgen, Jörg

    2003-09-30

    The salt-induced aggregation of the light-harvesting complex (LHC) II isolated from spinach and its correlation with fluorescence quenching of chlorophyll a is reported. Two transitions with distinctly different properties were observed. One transition related to salt-induced fluorescence quenching takes place at low salt concentration and is dependent both on temperature and detergent concentration. This transition seems to be related to a change in the lateral microorganization of LHCII. The second transition occurs at higher salt concentration and involves aggregation. It is independent of temperature and of detergent at sub-cmc concentrations. During the latter transition the small LHCII sheets (approximately 100 nm in diameter) are stacked to form larger aggregates of approximately 3 microm diameter. Based on the comparison between the physical properties of the transition and theoretical models, direct and specific binding of cations can practically be ruled out as driving force for the aggregation. It seems that in vitro aggregation of LHCII is caused by a complex mixture of different effects such as dielectric and electrostatic properties of the solution and surface charges.

  14. Polarization-independent waveguides in air holes photonic crystals and its slow light

    NASA Astrophysics Data System (ADS)

    Fan, Qingbin; Li, Chuanqi; Liu, Wei; Lu, Ye; Zhang, Dongchuang

    2016-12-01

    A line-defect waveguide in a triangular lattice photonic crystal (PC) made of air holes in dielectric is demonstrated to support transverse magnetic (TM) as well as transverse electric (TE) guided modes simultaneously. A group of suitable geometric parameters were found to make the guided bands overlapped by means of Genetic Algorithm. The optimized waveguide realizes a polarization-independent single-mode transmission and wide operating bandwidth which reaches 0.012 Δ ω a / (2 π c) . Moreover, the guided modes are shown to exhibit a wide-bandwidth slow light and an extremely low group velocity dispersion in most frequency range.

  15. 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.

  16. 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.

  17. ultraLM and miniLM: Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy

    PubMed Central

    2016-01-01

    In-resin fluorescence (IRF) protocols preserve fluorescent proteins in resin-embedded cells and tissues for correlative light and electron microscopy, aiding interpretation of macromolecular function within the complex cellular landscape. Dual-contrast IRF samples can be imaged in separate fluorescence and electron microscopes, or in dual-modality integrated microscopes for high resolution correlation of fluorophore to organelle. IRF samples also offer a unique opportunity to automate correlative imaging workflows. Here we present two new locator tools for finding and following fluorescent cells in IRF blocks, enabling future automation of correlative imaging. The ultraLM is a fluorescence microscope that integrates with an ultramicrotome, which enables ‘smart collection’ of ultrathin sections containing fluorescent cells or tissues for subsequent transmission electron microscopy or array tomography. The miniLM is a fluorescence microscope that integrates with serial block face scanning electron microscopes, which enables ‘smart tracking’ of fluorescent structures during automated serial electron image acquisition from large cell and tissue volumes. PMID:28090593

  18. 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.

  19. 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.

  20. Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an air atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Conway, Jim; Gogna, Gurusharan; Daniels, Stephen

    2016-09-01

    Two-photon Absorption Laser Induced Fluorescence (TALIF) is used to measure atomic oxygen number density [O] in an air Atmospheric Pressure Plasma Jet (APPJ). A novel technique based on photolysis of O2 is used to calibrate the TALIF system ensuring the same species (O) is probed during calibration and measurement. As a result, laser intensity can be increased outside the TALIF quadratic laser power region without affecting calibration reliability as any high intensity saturation effects will be identical for calibration and experiment. Higher laser intensity gives stronger TALIF signals helping overcome weak TALIF signals often experienced at atmospheric pressure due to collisional quenching. O2 photo-dissociation and two-photon excitation of the resulting [O] are both achieved within the same laser pulse. The photolysis [O] is spatially non-uniform and time varying. To allow valid comparison with [O] in a plasma, spatial and temporal correction factors are required. Knowledge of the laser pulse intensity I0(t), and wavelength allows correction factors to be found using a rate equation model. The air flow into the jet was fixed and the RF power coupled into the system varied. The resulting [O] was found to increase with RF power.

  1. Elemental analysis of tree leaves by total reflection X-ray fluorescence: New approaches for air quality monitoring.

    PubMed

    Bilo, Fabjola; Borgese, Laura; Dalipi, Rogerta; Zacco, Annalisa; Federici, Stefania; Masperi, Matteo; Leonesio, Paolo; Bontempi, Elza; Depero, Laura E

    2017-03-22

    This work shows that total reflection X-ray fluorescence (TXRF) is a fast, easy and successful tool to determine the presence of potentially toxic elements in atmospheric aerosols precipitations on tree leaves. Leaves are collected in eleven parks of different geographical areas of the Brescia city, Northern Italy, for environmental monitoring purposes. Two sample preparation procedures are considered: microwave acid digestion and the novel SMART STORE method for direct analysis. The latter consists in sandwiching a portion of the leaf between two organic foils, metals free, to save it from contamination and material loss. Mass composition of macro, micro and trace elements is calculated for digested samples, while relative elemental amount are obtained from direct analysis. Washed and unwashed leaves have a different composition in terms of trace elements. Differentiation occurs according to Fe, Pb and Cu contributions, considered as most representative of air depositions, and probably related to anthropogenic sources. Direct analysis is more representative of the composition of air precipitations. Advantages and drawbacks of the presented methods of sample preparation and TXRF analysis are discussed. Results demonstrate that TXRF allows to perform accurate and precise quantitative analysis of digested samples. In addition, direct analysis of leaves may be used as a fast and simple method for screening in the nanograms range.

  2. Comparison of light and fluorescence microscopy for xylem analysis in tomato pedicels during fruit development.

    PubMed

    Rancić, D; Quarrie, S Pekić; Terzić, M; Savić, S; Stikić, R

    2008-12-01

    The xylem hydraulic connection between shoot and fruits has previously been investigated, but contradictory conclusions were drawn about the presence of a flow resistance barrier in the pedicel. In this paper we were studying effect of the drought on the functional xylem vessels in the pedicels of tomato fruit. Commercial tomato genotype was grown in cabinet conditions under two watering regimes (full and deficit irrigation). An aqueous solution of eosin Y were used to visualize the path of water movement through tomato fruit pedicel and fluorescence microscopy observations were done on transversal and longitudinal sections. Dye uptake studies suggested that in well watered plants and in plants exposed to drought, a large majority of xylem vessels are not functional in water transport. Reduced-irrigation treatment significantly altered number and width of functional xylem elements in the fruit pedicel, especially in the abscission zone. This indicates that drought modifies xylem architecture and, thus, environmentally produced change in the hydraulic property of pedicel may affect fruit development.

  3. 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

  4. Photosynthetic acclimation to light in woody and herbaceous species: a comparison of leaf structure, pigment content and chlorophyll fluorescence characteristics measured in the field.

    PubMed

    Hallik, L; Niinemets, U; Kull, O

    2012-01-01

    Acclimation of foliage photosynthetic properties occurs with varying time kinetics, but structural, chemical and physiological factors controlling the kinetics of acclimation are poorly understood, especially in field environments. We measured chlorophyll fluorescence characteristics, leaf total carotenoid (Car), chlorophyll (Chl) and nitrogen (N) content and leaf dry mass per area (LMA) along vertical light gradients in natural canopies of the herb species, Inula salicina and Centaurea jacea, and tree species, Populus tremula and Tilia cordata, in the middle of the growing season. Presence of stress was assessed on the basis of night measurements of chlorophyll fluorescence. Our aim was to compare the light acclimation of leaf traits, which respond to light availability at long (LMA and N), medium (Chl a/b ratio, Car/Chl ratio) and short time scales (fluorescence characteristics). We found that light acclimation of nitrogen content per unit leaf area (N(area)), chlorophyll content per unit dry mass (Chl(mass)) and Chl/N ratio were related to modifications in LMA. The maximum PSII quantum yield (F(v) /F(m)) increased with increasing growth irradiance in I. salicina and P. tremula but decreased in T. cordata. Leaf growth irradiance, N content and plant species explained the majority of variability in chlorophyll fluorescence characteristics, up to 90% for steady-state fluorescence yield, while the contribution of leaf total carotenoid content was generally not significant. Chlorophyll fluorescence characteristics did not differ strongly between growth forms, but differed among species within a given growth form. These data highlight that foliage acclimation to light is driven by interactions between traits with varying time kinetics.

  5. 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.

  6. 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.

  7. Breakthrough of ultraviolet light from various brands of fluorescent lamps: lethal effects on DNA repair-defective bacteria.

    PubMed

    Hartman, P E; Biggley, W H

    1996-01-01

    In a comparative study of 17 pairs of 15 W fluorescent lamps intended for use in homes and purchased in local stores, we detect over 10-fold differences in UVB + UVC emissions between various lamps. This breakthrough of ultraviolet (UV) light is in part correlated with ability of lamps to kill DNA repair-defective recA-uvrB- Salmonella. Relative proficiency of lamps in eliciting photoreactivation of UV-induced DNA lesions also plays a prominent role in the relative rates of bacterial inactivation by emissions from different lamps. Lamps made in Chile, such as Philips brand lamps and one type of General Electric lamp, produce far less UVB + UVC and fail to kill recA-uvrB- bacteria. In contrast, all tested lamps manufactured in the USA, Hungary, and Japan exhibit readily observed deleterious biological effects. When an E. coli recA-uvrB-phr- (photolyase-negative) triple mutant is used for assay, lethal radiations are detected from all lamps, and single-hit exponential inactivation rates rather closely correlate to amount of directly measured UVB + UVC output of each pair of lamps. Although all lamps tested may meet international and United States standards for radiation safety, optimal practices in lamp manufacture are clearly capable of decreasing human exposure to indoor UV light.

  8. Breakthrough of ultraviolet light from various brands of fluorescent lamps: Lethal effects on DNA repair-defective bacteria

    SciTech Connect

    Hartman, P.E.; Biggley, W.H.

    1996-12-31

    In a comparative study of 17 pairs of 15 W fluorescent lamps intended for use in homes and purchased in local stores, we detect over 10-fold differences in UVB + UVC emissions between various lamps. This breakthrough of ultraviolet (UV) light is in part correlated with ability of lamps to kill DNA repair-defective recA{sup {minus}}uvrB{sup {minus}} Salmonella. Relative proficiency of lamps in eliciting photoreactivation of UV-induced DNA lesions also plays a prominent role in the relative rates of bacterial inactivation by emissions from different lamps. Lamps made in Chile, such as Phillips brand lamps and one type of General Electric lamp, produce far less UVB + UVC and fail to kill recA{sup {minus}} uvrB{sup {minus}} bacteria. In contrast, all tested lamps manufactured in the USA, Hungary, and Japan exhibit readily observed deleterious biological effects. When an E. coli recA{sup {minus}} uvrB{sup {minus}} phr{sup {minus}} (photolyase-negative) triple mutant is used for assay, lethal radiations are detected from all lamps, and single-hit exponential inactivation rates rather closely correlate to amount of directly measured UVB + UVC output of each pair of lamps. Although all lamps tested may meet international and Unite States standards for radiation safely, optimal practices in lamp manufacture are clearly capable of decreasing human exposure to indoor UV light. 38 refs., 3 figs., 1 tab.

  9. Fluorescent light mediated a green synthesis of silver nanoparticles using the protein extract of weaver ant larvae.

    PubMed

    Khamhaengpol, Arunrat; Siri, Sineenat

    2016-10-01

    Alternative to crude plant extracts, a crude protein extract derived from animal cells is one of the potential sources of biomolecules for mediating a reduction of silver ions and a formation of silver nanoparticles (AgNPs) under a mild condition, which very few works have been reported. This work demonstrated a use of the protein extract of weaver ant larvae as a bio-facilitator for a simple, green synthesis of AgNPs under fluorescent light at room temperature. The protein extract of weaver ant larvae exhibited the reducing and antioxidant activities, which assisted a formation of AgNPs in the reaction containing only silver nitrate under light exposure. Transmission electron microscopy images revealed the dispersed, spherical AgNPs with an average size of 7.87±2.54nm. The maximum surface plasmon resonance (SPR) band of the synthesized AgNPs was at 435nm. The energy-dispersive X-ray analysis revealed that silver was a major element of the particles. The identity of AgNPs was confirmed by X-ray diffraction pattern, selected area electron diffraction and high resolution transmission electron microscopy analyses, which demonstrated the planes of face centered cubic silver. The synthesized AgNPs showed antibacterial activity against both Escherichia coli and Staphylococcus aureus with the minimum bactericidal concentration (MBC) values equally at 250μg/ml, suggesting their potential application as an effective antibacterial agent.

  10. Blue organic light-emitting diodes realizing external quantum efficiency over 25% using thermally activated delayed fluorescence emitters.

    PubMed

    Miwa, Takuya; Kubo, Shosei; Shizu, Katsuyuki; Komino, Takeshi; Adachi, Chihaya; Kaji, Hironori

    2017-03-21

    Improving the performance of blue organic light-emitting diodes (OLEDs) is needed for full-colour flat-panel displays and solid-state lighting sources. The use of thermally activated delayed fluorescence (TADF) is a promising approach to efficient blue electroluminescence. However, the difficulty of developing efficient blue TADF emitters lies in finding a molecular structure that simultaneously incorporates (i) a small energy difference between the lowest excited singlet state (S1) and the lowest triplet state (T1), ΔE ST, (ii) a large oscillator strength, f, between S1 and the ground state (S0), and (iii) S1 energy sufficiently high for blue emission. In this study, we develop TADF emitters named CCX-I and CCX-II satisfying the above requirements. They show blue photoluminescence and high triplet-to-singlet up-conversion yield. In addition, their transition dipole moments are horizontally oriented, resulting in further increase of their electroluminescence efficiency. Using CCX-II as an emitting dopant, we achieve a blue OLED showing a high external quantum efficiency of 25.9%, which is one of the highest EQEs in blue OLEDs reported previously.

  11. Quantification of Fungal DNA by Using Fluorescence Resonance Energy Transfer and the Light Cycler System

    PubMed Central

    Loeffler, Juergen; Henke, Norbert; Hebart, Holger; Schmidt, Diethard; Hagmeyer, Lars; Schumacher, Ulrike; Einsele, Hermann

    2000-01-01

    The Light Cycler technique combines rapid in vitro amplification of DNA in glass capillaries with real-time species determination and quantification of DNA load. We have established a quantitative PCR protocol for two clinically important pathogens, Candida albicans and Aspergillus fumigatus. The sensitivity of the assay was comparable to those of previously described PCR protocols (5 CFU/ml). Specific detection of C. albicans and A. fumigatus could be achieved. The assay showed a high reproducibility of 96 to 99%. The assay was linear in a range between 101 and 104 Aspergillus conidia. As capillaries do not have to be reopened for post-PCR analysis, the risk of carryover contaminations could be minimized. The Light Cycler allowed quantification of the fungal loads in a limited number of clinical specimens from patients with hematological malignancies and histologically proven invasive fungal infections. Five of nine positive samples had fungal loads between 5 and 10 CFU/ml of blood, two of nine positive samples had fungal loads between 10 and 100 CFU/ml of blood, and two of nine samples had fungal loads of more than 100 CFU/ml of blood. All samples were also found to be PCR positive by PCR–enzyme-linked immunosorbent assay analysis. PMID:10655350

  12. Self-assembly-induced far-red/near-infrared fluorescence light-up for detecting and visualizing specific protein-Peptide interactions.

    PubMed

    Wang, Huaimin; Liu, Jie; Han, Aitian; Xiao, Nannan; Xue, Zhaosheng; Wang, Gang; Long, Jiafu; Kong, Deling; Liu, Bin; Yang, Zhimou; Ding, Dan

    2014-02-25

    Understanding specific protein-peptide interactions could offer a deep insight into the development of therapeutics for many human diseases. In this work, we designed and synthesized a far-red/near-infrared (FR/NIR) fluorescence light-up probe (DBT-2EEGWRESAI) by simply integrating two tax-interacting protein-1 (TIP-1)-specific peptide ligands (EEGWRESAI) with one 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DBT) unit. We first demonstrated that DBT is an environment-sensitive fluorophore with FR/NIR fluorescence due to its strong charge transfer character in the excited state. Thanks to the environmental sensitivity of DBT, the probe DBT-2EEGWRESAI is very weakly fluorescent in aqueous solution but lights up its fluorescence when the probe specifically binds to TIP-1 protein or polyprotein (ULD-TIP-1 tetramer). It is found that the DBT-2EEGWRESAI/TIP-1 protein and the DBT-2EEGWRESAI/ULD-TIP-1 tetramer could self-assemble into spherical nanocomplexes and a nanofiber network, respectively, which lead to probe fluorescence turn-on through providing DBT with a hydrophobic microenvironment. By virtue of the self-assembly-induced FR/NIR fluorescence turn-on, DBT-2EEGWRESAI can detect and visualize specific protein/polyprotein-peptide interactions in both solution and live bacteria in a high contrast and selective manner.

  13. Identification of Daqingye and Banlangen including crude drugs and decoction dregs from three plant species by normal light and fluorescence microscopy.

    PubMed

    Xiaojing, Wan; Liang, Zhitao; Chen, Hu-Biao; Zhao, Zhongzhen; Li, Ping

    2013-08-01

    Daqingye and Banlangen are commonly used Chinese medicinal materials derived from the leaves and roots of Isatis indigotica Fort., respectively, which clinical effects have been confirmed by many studies in recent years. However, many problems have arisen concerning the quality and identity of materials sold in the market under these two names. Thus, the identification of Daqingye and Banlangen has drawn public attention. In this work, transverse sections of Daqingye and Banlangen from I. indigotica Fort. and two easily confused species, namely Baphicacanthus cusia (Nees) Bremek. and Clerodendrum cyrtophyllum Turcz., were investigated with normal light and fluorescence microscopy. The distinguishing features were 7-9 vascular bundles, cystoliths and nonglandular hairs in the leaves of I. indigotica, B. cusia, and C. cyrtophyllum, respectively. The Banlangen could be distinguished according to the characteristics of parenchymous cells, cystoliths, and stone cells. Moreover, the fluorescence features of Daqingye and Banlangen investigated in this study can provide direct points for differentiating those samples. Importantly, whether the crude drugs were decocted could be easily identified by their different fluorescence features, which can ensure their quality in clinical application. This is the first report to distinguish the three species that are commonly found in the market sold as Daqingye and Banlangen by normal light and fluorescence microscopy. This work indicates that the combination of normal light and fluorescence microscopy could be powerful, convenient, and economical for authenticating Daqingye and Banlangen from the three species, including crude drugs and decoction dregs.

  14. 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

  15. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    NASA Astrophysics Data System (ADS)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  16. 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.

  17. Single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for block copolymer nanostructures via blue-light-switchable FRAP.

    PubMed

    Gong, Wen-Liang; Yan, Jie; Zhao, Ling-Xi; Li, Chong; Huang, Zhen-Li; Tang, Ben Zhong; Zhu, Ming-Qiang

    2016-11-02

    Photoswitchable fluorophores are promising in single-molecule optical devices and super-resolution fluorescence imaging, especially in single-molecule photo-activated localization microscopy (PALM) or stochastic optical reconstruction microscopy (STORM). However, the scarcity of current photoswitchable fluorophores stimulates researchers to develop complicated optical systems and processing software, in accordance with the limited photoswitchable fluorescent proteins and organic fluorophores. Previous efforts to develop synthetic photoswitchable fluorophores have exhibited their promising potential in super-resolution fluorescence imaging. Here, we have designed and synthesized a fluorescence molecular switch with reversible green emission, a napthalimide-hexaarylbiimidazole conjugate (NI-N-HABI), which exhibits strong fluorescence in the emissive state, with fast thermal fading of the photochromism and spontaneous fluorescence recovery after photobleaching (FRAP) induced by blue-light. The photoswitchable fluorophore enables the red-edge wavelength of the optical response to red-shift from the initial near-UV region at less than 400 nm, to 500 nm. The relatively fast fading speed of NI-N-HABI and its sensitivity to longer blue-light irradiation (400-500 nm) have allowed simplification of the optical microscopic system from a two-wavelength laser source to a single-wavelength laser. We applied NI-N-HABI in single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for the self-assembly and solvent annealing of amphiphilic block polymers, with 50 nm of optical resolution. Single-wavelength-controlled dynamic super-resolution fluorescence imaging facilitates nanoscale optical visualization for the dynamic physical and chemical fluctuation processes of stimuli-responsive nanostructures.

  18. Design and evaluation of capillary coupled with optical fiber light-emitting diode induced fluorescence detection for capillary electrophoresis.

    PubMed

    Ji, Hongyun; Li, Meng; Guo, Lihong; Yuan, Hongyan; Wang, Chunling; Xiao, Dan

    2013-09-01

    A new detector, capillary coupled with optical fiber LED-induced fluorescence detector (CCOF-LED-IFD, using CCOF for short), is introduced for CE. The strategy of the present work was that the optical fiber and separation capillary were, in the parallel direction, fastened in a fixation capillary with larger inner diameter. By employing larger inner diameter, the fixation capillary allowed the large diameter of the optical fiber to be inserted into it. By transmitting an enhanced excitation light through the optical fiber, the detection sensitivity was improved. The advantages of the CCOF-CE system were validated by the detection of riboflavin, and the results were compared to those obtained by the in-capillary common optical fiber LED-induced fluorescence detector (IC-COF-LED-IFD, using COF for short). The LODs of CCOF-CE and COF-CE were 0.29 nM and 11.0 nM (S/N = 3), respectively. The intraday (n = 6) repeatability and interday (n = 6) reproducibility of migration time and corresponding peak area for both types of CE were all less than 1.10 and 3.30%, respectively. The accuracy of the proposed method was judged by employing standard addition method, and recoveries obtained were in the range of 98.0-102.4%. The results indicated that the sensitivity of the proposed system was largely improved, and that its reproducibility and accuracy were satisfactory. The proposed system was successfully applied to separate and determine riboflavin in real sample.

  19. Enamel demineralization and remineralization under plaque fluid-like conditions: a quantitative light-induced fluorescence study.

    PubMed

    Lippert, F; Butler, A; Lynch, R J M

    2011-01-01

    The present study investigated de- and remineralization in enamel lesions under plaque fluid (PF)-like conditions using quantitative light-induced fluorescence (QLF). Preformed lesions were exposed to partially saturated lactic acid solutions, varying in pH and fluoride concentration ([F]) based on a 5 × 3 factorial study design (0/0.1/0.5/1.5/4 ppm F; pH 4.9/5.2/5.5). Average fluorescence loss (ΔF) was monitored for 11 days. Subsequently, lesions were demineralized in a partially saturated acetic acid solution for two 24-hour periods. Data were analyzed using repeated measures analysis of covariance. Lesions exposed to PF at 4 ppm F and pH 5.5 showed not only the most remineralization (ΔΔF = 28.2 ± 14.0%) for all groups after 11 days, but also the most demineralization (ΔΔF = -19.3 ± 13.5%) after subsequent acetic acid exposure. Increased [F] resulted in more remineralization, regardless of pH. Higher pH values resulted in more remineralization. No remineralization was observed in lesions exposed to F-free solutions, regardless of pH. Remineralization was noticeable under the following conditions: pH 4.9 - [F] = 4 ppm, pH 5.2 - [F] ≥ 1.5 ppm, and pH 5.5 - [F] ≥ 0.5 ppm. Overall, [F] had a stronger effect on remineralization than pH. Subsequent demineralization showed that little protection was offered by PF-like solutions, and further demineralization compared with baseline was observed on lesions not remineralized initially. [F] had a stronger effect on net mineral change than pH. The present study has shown that QLF is a valuable tool in studying lesion de- and remineralization under PF-like conditions, where [F] was shown to be more important than pH.

  20. 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.

  1. 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.

  2. 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.

  3. Synthesis of fluorescent core-shell nanomaterials and strategies to generate white light

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Kaur, Ramanjot; Pandey, O. P.; Wei, Xueyong; Sharma, Manoj

    2015-07-01

    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.

  4. Improving the optical performance of InGaN light-emitting diodes by altering light reflection and refraction with triangular air prism arrays.

    PubMed

    Kang, Ji Hye; Kim, Hyung Gu; Chandramohan, S; Kim, Hyun Kyu; Kim, Hee Yun; Ryu, Jae Hyoung; Park, Young Jae; Beak, Yun Seon; Lee, Jeong-Sik; Park, Joong Seo; Lysak, Volodymyr V; Hong, Chang-Hee

    2012-01-01

    The effect of triangular air prism (TAP) arrays with different distance-to-width (d/w) ratios on the enhancement of light extraction efficiency (LEE) of InGaN light-emitting diodes (LEDs) is investigated. The TAP arrays embedded at the sapphire/GaN interface act as light reflectors and refractors, and thereby improve the light output power due to the redirection of light into escape cones on both the front and back sides of the LED. Enhancement in radiometric power as high as 117% and far-field angle as low as 129° are realized with a compact arrangement of TAP arrays compared with that of a conventional LED made without TAP arrays under an injection current of 20 mA.

  5. 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

  6. CH3 NH3 PbBr3 Perovskite Nanocrystals as Efficient Light-Harvesting Antenna for Fluorescence Resonance Energy Transfer.

    PubMed

    Muthu, Chinnadurai; Vijayan, Anuja; Nair, Vijayakumar C

    2017-03-16

    Hybrid perovskites have created enormous research interest as a low-cost material for high-performance photovoltaic devices, light-emitting diodes, photodetectors, memory devices and sensors. Perovskite materials in nanocrystal form that display intense luminescence due to the quantum confinement effect were found to be particularly suitable for most of these applications. However, the potential use of perovskite nanocrystals as a light-harvesting antenna for possible applications in artificial photosynthesis systems is not yet explored. In the present work, we study the light-harvesting antenna properties of luminescent methylammonium lead bromide (CH3 NH3 PbBr3 )-based perovskite nanocrystals using fluorescent dyes (rhodamine B, rhodamine 101, and nile red) as energy acceptors. Our studies revealed that CH3 NH3 PbBr3 nanocrystals are an excellent light-harvesting antenna, and efficient fluorescence resonance energy transfer occurs from the nanocrystals to fluorescent dyes. Further, the energy transfer efficiency is found to be highly dependent on the number of anchoring groups and binding ability of the dyes to the surface of the nanocrystals. These observations may have significant implications for perovskite-based light-harvesting devices and their possible use in artificial photosynthesis systems.

  7. 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

  8. 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.

  9. Different crystal morphologies lead to slightly different conformations of light-harvesting complex II as monitored by variations of the intrinsic fluorescence lifetime.

    PubMed

    van Oort, Bart; Maréchal, Amandine; Ruban, Alexander V; Robert, Bruno; Pascal, Andrew A; de Ruijter, Norbert C A; van Grondelle, Rienk; van Amerongen, Herbert

    2011-07-21

    In 2005, it was found that the fluorescence of crystals of the major light-harvesting complex LHCII of green plants is significantly quenched when compared to the fluorescence of isolated LHCII (A. A. Pascal et al., Nature, 2005, 436, 134-137). The Raman spectrum of crystallized LHCII was also found to be different from that of isolated LHCII but very similar to that of aggregated LHCII, which has often been considered a good model system for studying nonphotochemical quenching (NPQ), the major protection mechanism of plants against photodamage in high light. It was proposed that in the crystal LHCII adopts a similar (quenching) conformation as during NPQ and indeed similar changes in the Raman spectrum were observed during NPQ in vivo (A. V. Ruban et al., Nature, 2007, 450, 575-579). We now compared the fluorescence of various types of crystals, differing in morphology and age. Each type gave rise to its own characteristic mono-exponential fluorescence lifetime, which was 5 to 10 times shorter than that of isolated LHCII. This indicates that fluorescence is not quenched by random impurities and packing defects (as proposed recently by T. Barros et al., EMBO Journal, 2009, 28, 298-306), but that LHCII adopts a particular structure in each crystal type, that leads to fluorescence quenching. Most interestingly, the extent of quenching appears to depend on the crystal morphology, indicating that also the crystal structure depends on this crystal morphology but at the moment no data are available to correlate the crystals' structural changes to changes in fluorescence lifetime.

  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. Spectroscopy of Light Emission from a Scanning Tunneling Microscope in Air

    NASA Astrophysics Data System (ADS)

    Péchou, R.; Coratger, R.; Girardin, C.; Ajustron, F.; Beauvillain, J.

    1996-11-01

    Light emission has been detected at the tip-sample junction of a Scanning Tunneling Microscope (S.T.M.) in air on noble metallic surfaces. A spectroscopic study of emitted photons for Au-Au and PtIr-Au tunneling junctions is presented. The general aspect of the spectra depends on the materials used in the junctions; a study of the spectra as a function of tunneling current and surface bias voltage reveals similar and reproducible characteristics. Une émission de lumière a été détectée au niveau de la jonction pointe-surface d'un microscope à effet tunnel dans l'air sur des surfaces de métaux nobles. Une étude spectroscopique des photons émis par des jonctions tunnel Au-Au et PtIr-Au est présentée. L'aspect général des spectres dépend des matériaux utilisés ; une étude en fonction du courant tunnel et de la tension de polarisation de la jonction révéle des caractéristiques similaires et reproductibles.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Enantiomerically pure trans-beta-lactams from alpha-amino acids via compact fluorescent light (CFL) continuous-flow photolysis.

    PubMed

    Vaske, Yvette S Mimieux; Mahoney, Maximillian E; Konopelski, Joseph P; Rogow, David L; McDonald, William J

    2010-08-18

    Photolysis of alpha-diazo-N-methoxy-N-methyl (Weinreb) beta-ketoamides derived from enantiomerically pure (EP) alpha-amino acids affords the corresponding EP beta-lactams via an intramolecular Wolff rearrangement. The photochemistry is promoted with either standard UV irradiation or through the use of a 100 W compact fluorescent light; the latter affords a safe and environmentally friendly alternative to standard photolysis conditions. A continuous-flow photochemical reactor made from inexpensive laboratory equipment reduced reaction times and was amenable to scale-up. The diastereoselectivity (cis or trans) of the product beta-lactams has been shown to vary from modest to nearly complete. An extremely facile, atom-economical method for the epimerization of the product mixture to the trans isomer, which is generally highly crystalline, has been developed. Evidence for C3 epimerization of Weinreb amide structures via a nonbasic, purely thermal route is presented. Subsequent transformations of both the Weinreb amide at C3 (beta-lactam numbering) and the amino acid side chain at C4 are well-tolerated, allowing for a versatile approach to diverse beta-lactam structures. The technology is showcased in the synthesis of a common intermediate used toward several carbapenem-derived structures starting from unfunctionalized aspartic acid.

  18. Enantiomerically Pure trans-β-Lactams from α-Amino Acids via Compact Fluorescent Light (CFL) Continuous Flow Photolysis

    PubMed Central

    Mimieux Vaske, Yvette S.; Mahoney, Maximillian E.; Konopelski, Joseph P.; Rogow, David L.; McDonald, William J.

    2010-01-01

    Photolysis of α-diazo N-methoxy-N-methyl (Weinreb) β-ketoamides derived from enantiomerically pure (EP) α-amino acids affords the corresponding EP β-lactam via an intramolecular Wolff rearrangement. Photochemistry is promoted with either standard UV irradiation or through the use of a 100W compact fluorescent light (CFL); the latter affords a safe and environmentally friendly alternative to standard photolysis conditions. A continuous-flow photochemical reactor, made from inexpensive laboratory equipment, expedites reaction times and is amenable to scale-up. Diastereoselectivity (cis or trans) of the product β-lactams has been shown to vary from modest to nearly complete. An extremely facile, atom-economical method for the epimerization of the product mixture to the trans isomer, generally highly crystalline, has been developed. Evidence is presented for C-3 epimerization of Weinreb amide structures via a non-basic, purely thermal route. Subsequent transformations of both the Weinreb amide at C-3 (β-lactam numbering) and amino acid side chain at C-4 are well tolerated, allowing for a versatile approach to diverse β-lactam structures. The technology is showcased in the synthesis of a common intermediate used toward several carbapenem-derived structures starting from unfunctionalized aspartic acid. PMID:20698705

  19. 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.

  20. 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

    2016-03-03

    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.

  1. 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.

  2. 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.

  3. 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

  4. High Power Efficiency Blue-to-Green Organic Light-Emitting Diodes Using Isonicotinonitrile-Based Fluorescent Emitters.

    PubMed

    Sasabe, Hisahiro; Onuma, Natsuki; Nagai, Yuji; Ito, Takashi; Kido, Junji

    2017-03-16

    Herein, 9,10-dihydro-9,9-dimethylacridine (Ac) or phenoxazine (PXZ)-substituted isonicotinonitrile (INN) derivatives, denoted as 2AcINN, 26AcINN, and 26PXZINN, were developed as a series of thermally activated delayed fluorescence (TADF) emitters. These emitters showed reasonably high photoluminescence quantum yields of 71-79 % in the host films and high power efficiency organic light-emitting diodes (OLEDs). Sky-blue emitter 26AcINN exhibited a low turn-on voltage of 2.9 V, a high external quantum efficiency (ηext ) of 22 %, and a high power efficiency (ηp ) of 66 lm W(-1) with Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.22, 0.45), whereas green emitter 26PXZINN exhibited a low turn-on voltage of 2.2 V, a high ηext of 22 %, and a high ηp of 99 lm W(-1) with CIE chromaticity coordinates of (0.37, 0.58). These performances are among the best for TADF OLEDs to date.

  5. A fluorescent light-up aggregation-induced emission probe for screening gefitinib-sensitive non-small cell lung carcinoma.

    PubMed

    Hu, Yi; Shi, Leilei; Su, Yue; Zhang, Chuan; Jin, Xin; Zhu, Xinyuan

    2017-03-07

    Fluorescent light-up probes with aggregation-induced emission (AIE) characteristics have been focused on recently. In this report, a new fluorescent probe, namely, DEVD-TPE, which consisted of the substrate peptide Asp-Glu-Val-Asp (DEVD) and the AIE reporter group tetraphenylethene (TPE), was developed for detecting caspase-3 in living cells. In a slightly alkaline solution, the DEVD-TPE probe displayed almost no fluorescence owing to the dynamic rotation of the phenyl rings in solution. However, DEVD-TPE exhibited significant fluorescence when it was cleaved by caspase-3, as well as when the reporter group TPE underwent aggregation. The epidermal growth factor receptor (EGFR) inhibitor gefitinib was used for determining the screening efficacy of the probe for different non-small cell lung carcinoma (NSCLC) cell lines, namely, HCC827, A549 and H1650 cells. Cell proliferation and apoptosis assays indicated that the three cell lines had different sensitivities to gefitinib. The results of analysis by living-cell fluorescence imaging and flow cytometry were consistent with those of the cell proliferation and apoptosis assays. This demonstrated that our probe could detect caspase-3 in living cells, which confirmed the apoptosis of NSCLC cells. Furthermore, our probe indicated that gefitinib was more efficient against HCC827 cells than against the other two NSCLC cell lines. This report proves that the fluorescent probe DEVD-TPE is highly sensitive to caspase-3 and has potential prospects in the rapid screening of NSCLC.

  6. Evaluation of a portable X-ray fluorescence instrument for the determination of lead in workplace air samples.

    PubMed

    Morley, J C; Clark, C S; Deddens, J A; Ashley, K; Roda, S

    1999-05-01

    Occupational Safety and Health Administration (OSHA) regulations for worker exposure to lead specify worker protection levels based upon airborne concentrations of lead dust. The rapid, on-site determination of lead in air filter samples using a portable x-ray fluorescence (XRF) instrument with an attachment to hold the filter would expedite the exposure assessment process and facilitate compliance with the OSHA standards. A total of 65 lead in air filter samples were collected at bridge blasting lead-abatement projects using closed-faced, 37-mm cassettes with pre-loaded 0.8 micron pore size mixed cellulose ester membrane filters. The lead loading range of the data set was 0.1-1514.6 micrograms (micrograms) of lead/sample. Samples were initially analyzed with a field portable XRF (NITON 700) using an experimental non-destructive XRF method. Samples were subsequently analyzed using National Institute for Occupational Safety and Health (NIOSH) Method 7105 (Graphite Furnace AA) as a reference analytical method. The paired data were not normally distributed; therefore, the non-parametric Wilcoxon signed rank test was used for statistical analysis. There was no statistically significant difference between data from the field portable XRF method and the NIOSH method (p-value = 0.72). Linear regression of the data resulted in a slope of 0.959, a y-intercept of 5.20 micrograms, and an r2 of 0.985. The XRF limit of detection and limit of quantitation were determined to be 6.2 and 17 micrograms of lead/sample, respectively. The XRF method accuracy was +/- 16.4% (7.1%-27%, 90% confidence interval). The data presented in this study indicate that field-portable XRF can be used for the analysis of lead air filter samples over the range of 17 to 1500 micrograms of lead/sample. The practicing industrial hygienist can use field-portable XRF to produce a rapid, on-site determination of lead exposure that can immediately be communicated to workers and help identify appropriate levels

  7. 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.

  8. 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.

  9. 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.

  10. Field Commissioning of a Daylight-Dimming Lighting System.

    ERIC Educational Resources Information Center

    Floyd, David B.; Parker, Danny S.

    A Florida elementary school cafeteria, retrofitted with a fluorescent lighting system that dims in response to available daylight, was evaluated through real time measurement of lighting and air conditioning power, work plane illumination, and interior/exterior site conditions. The new system produced a 27 percent reduction in lighting power due…

  11. Analysis of Light Gathering Abilities of Dynamically Solidified Micro-lenses, and Their Implementation to Improve Sensitivity of Fluorescent PCR Micro-detectors.

    PubMed

    Wu, Jian; Guo, Wei; Wang, Chunyan; Yu, Kuanxin; Chen, Tao; Li, Yinghui

    2015-06-01

    Fluorescent polymerase chain reaction (PCR) is becoming the preferred method of quantitative analysis due to its high specificity and sensitivity. We propose to use a new kind of micro-lens, dynamically solidified with optic glue, to improve the sensitivity of fluorescent PCR micro-detector. We developed light ray track equations for these lenses and used them to calculate relative light intensity distribution curve for stimulation lenses and illumination point probability distribution curve for detection lenses. We manufactured dynamically solidified micro-lenses using optic glue NOA61, and measured their light gathering ability. Lenses with radius/thickness (R/H) ratio of 4 reached light focusing ratio of 3.85 (stimulation lens) and photon collection efficiency of 0.86 (detection lens). We then used dynamically solidified lenses in PCR fluorescence micro-detector and analyzed their effect on the detector sensitivity. We showed that the use of dynamically solidified micro-lenses with R/H = 4 resulted in over 4.4-fold increased sensitivity of the detector.

  12. Selective excitation of tryptophan fluorescence decay in proteins using a subnanosecond 295 nm light-emitting diode and time-correlated single-photon counting

    NASA Astrophysics Data System (ADS)

    McGuinness, Colin D.; Sagoo, Kulwinder; McLoskey, David; Birch, David J. S.

    2005-06-01

    We demonstrate an AlGaN light-emitting diode (LED) giving pulses of ˜600ps full width half maximum, 0.35μW average power, 0.6mW peak power, and ˜12nm bandwidth at 295nm. This source is ideal for protein intrinsic tryptophan fluorescence decay research without the unwanted excitation of tyrosine and paves the way to lab-on-a-chip protein assays using fluorescence decay times. Fluorescence decay and anisotropy decay measurements of human serum albumin are reported and the usefulness of the 295nm LED demonstrated in comparisons with a nanosecond flashlamp and LEDs with nominal wavelength emission of 280nm.

  13. Determination of aflatoxins in air samples of refuse-derived fuel by thin-layer chromatography with laser-induced fluorescence spectrometric detection

    SciTech Connect

    Bicking, M.K.L.; Kniseley, R.N.; Svec, H.J.

    1983-02-01

    An analytical method is described which allows determination of aflatoxins in a complex matrix. An apparatus has been developed that quantitates fluorescent compounds on thin-layer chromatography plates. A nitrogen laser excitation source produces a detection limit of 10 pg for four aflatoxins. Aflatoxin B1 has been found at levels up to 17 ppb in solid samples collected from the air at a plant which produces refuse-derived fuel. 7 figures, 1 table.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. New air Cherenkov light detectors to study mass composition of cosmic rays with energies above knee region

    NASA Astrophysics Data System (ADS)

    Tsunesada, Yoshiki; Katsuya, Ryoichi; Mitsumori, Yu; Nakayama, Keisuke; Kakimoto, Fumio; Tokuno, Hisao; Tajima, Norio; Miranda, Pedro; Salinas, Juan; Tavera, Wilfredo

    2014-11-01

    We have installed a hybrid detection system for air showers generated by cosmic rays with energies greater than 3 ×1015 eV at Mount Chacaltaya (5200 m above the sea level), in order to study the mass composition of cosmic rays above the knee region. This detection system comprises an air shower array with 49 scintillation counters in an area of 500 m×650 m, and seven new Cherenkov light detectors installed in a radial direction from the center of the air shower array with a separation of 50 m. It is known that the longitudinal development of a particle cascade in the atmosphere strongly depends on the type of the primary nucleus, and an air shower initiated by a heavier nucleus develops faster than that by a lighter primary of the same energy, because of the differences in the interaction cross-section and the energy per nucleon. This can be measured by detecting the Cherenkov radiation emitted from charged particles in air showers at higher altitudes. In this paper we describe the design and performance of our new non-imaging Cherenkov light detectors at Mount Chacaltaya that are operated in conjunction with the air shower array. The arrival directions and energies of air showers are determined by the shower array, and information about the primary masses is obtained from the Cherenkov light data including the time profiles and lateral distributions. The detector consists of photomultiplier tube (PMT), high-speed ADCs, other control modules, and data storage device. The Cherenkov light signals from an air shower are typically 10-100 ns long, and the waveforms are digitized with a sampling frequency of 1 GHz and recorded in situ without long-distance analog signal transfers. All the Cherenkov light detectors record their time-series data by receiving a triggering signal transmitted from the trigger module of the air shower array, which is fired by a coincidence of shower signals in four neighboring scintillation counters. The optical characteristics of the

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. The diatom Phaeodactylum tricornutum adjusts nonphotochemical fluorescence quenching capacity in response to dynamic light via fine-tuned Lhcx and xanthophyll cycle pigment synthesis.

    PubMed

    Lepetit, Bernard; Gélin, Gautier; Lepetit, Mariana; Sturm, Sabine; Vugrinec, Sascha; Rogato, Alessandra; Kroth, Peter G; Falciatore, Angela; Lavaud, Johann

    2017-04-01

    Diatoms contain a highly flexible capacity to dissipate excessively absorbed light by nonphotochemical fluorescence quenching (NPQ) based on the light-induced conversion of diadinoxanthin (Dd) into diatoxanthin (Dt) and the presence of Lhcx proteins. Their NPQ fine regulation on the molecular level upon a shift to dynamic light conditions is unknown. We investigated the regulation of Dd + Dt amount, Lhcx gene and protein synthesis and NPQ capacity in the diatom Phaeodactylum tricornutum after a change from continuous low light to 3 d of sine (SL) or fluctuating (FL) light conditions. Four P. tricornutum strains with different NPQ capacities due to different expression of Lhcx1 were included. All strains responded to dynamic light comparably, independently of initial NPQ capacity. During SL, NPQ capacity was strongly enhanced due to a gradual increase of Lhcx2 and Dd + Dt amount. During FL, cells enhanced their NPQ capacity on the first day due to increased Dd + Dt, Lhcx2 and Lhcx3; already by the second day light acclimation was accomplished. While quenching efficiency of Dt was strongly lowered during SL conditions, it remained high throughout the whole FL exposure. Our results highlight a more balanced and cost-effective photoacclimation strategy of P. tricornutum under FL than under SL conditions.

  6. 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

  7. Bypass Ratio: The US Air Force and Light-Attack Aviation

    DTIC Science & Technology

    2013-06-01

    and largely shaped how the Air Force viewed itself. In an attempt to define itself as a new service, the Air Force advertised quick wars. These...existing knowledge to the core.”5 If a new paradigm must be born from crisis, what kind of crisis could cause the Air Force to rethink its stance on the...and AirSea Battle. This theory correlates with the pivot in emphasis to the Asia -Pacific region and the relative decrease in spending cuts for the Air

  8. 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.

  9. Increasing light capture in silicon solar cells with encapsulants incorporating air prisms to reduce metallic contact losses.

    PubMed

    Chen, Fu-Hao; Pathreeker, Shreyas; Kaur, Jaspreet; Hosein, Ian D

    2016-10-31

    Silicon solar cells are the most widely deployed modules owing to their low-cost manufacture, large market, and suitable efficiencies for residential and commercial use. Methods to increase their solar energy collection must be easily integrated into module fabrication. We perform a theoretical and experimental study on the light collection properties of an encapsulant that incorporates a periodic array of air prisms, which overlay the metallic front contacts of silicon solar cells. We show that the light collection efficiency induced by the encapsulant depends on both the shape of the prisms and angle of incidence of incoming light. We elucidate the changes in collection efficiency in terms of the ray paths and reflection mechanisms in the encapsulant. We fabricated the encapsulant from a commercial silicone and studied the change in the external quantum efficiency (EQE) on an encapsulated, standard silicon solar cell. We observe efficiency enhancements, as compared to a uniform encapsulant, over the visible to near infrared region for a range of incident angles. This work demonstrates exactly how a periodic air prism architecture increases light collection, and how it may be designed to maximize light collection over the widest range of incident angles.

  10. Far-red/near-infrared fluorescence light-up probes for specific in vitro and in vivo imaging of a tumour-related protein.

    PubMed

    Chen, Chao; Hua, Yongquan; Hu, Yawen; Fang, Yuan; Ji, Shenglu; Yang, Zhimou; Ou, Caiwen; Kong, Deling; Ding, Dan

    2016-03-17

    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.

  11. 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.

  12. 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

  13. QM/MM study on the light emitters of aequorin chemiluminescence, bioluminescence, and fluorescence: a general understanding of the bioluminescence of several marine organisms.

    PubMed

    Chen, Shu-Feng; Ferré, Nicolas; Liu, Ya-Jun

    2013-06-24

    Aequorea victoria is a type of jellyfish that is known by its famous protein, green fluorescent protein (GFP), which has been widely used as a probe in many fields. Aequorea has another important protein, aequorin, which is one of the members of the EF-hand calcium-binding protein family. Aequorin has been used for intracellular calcium measurements for three decades, but its bioluminescence mechanism remains largely unknown. One of the important reasons is the lack of clear and reliable knowledge about the light emitters, which are complex. Several neutral and anionic forms exist in chemiexcited, bioluminescent, and fluorescent states and are connected with the H-bond network of the binding cavity in the protein. We first theoretically investigated aequorin chemiluminescence, bioluminescence, and fluorescence in real proteins by performing hybrid quantum mechanics and molecular mechanics methods combined with a molecular dynamics method. For the first time, this study reported the origin and clear differences in the chemiluminescence, bioluminescence and fluorescence of aequorin, which is important for understanding the bioluminescence not only of jellyfish, but also of many other marine organisms (that have the same coelenterazine caved in different coelenterazine-type luciferases).

  14. 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

  15. Conducting thermomechanical fatigue test in air at light water reactor relevant temperature intervals

    NASA Astrophysics Data System (ADS)

    Ramesh, Mageshwaran; Leber, Hans J.; Diener, Markus; Spolenak, Ralph

    2011-08-01

    In Light Water Reactors (LWR), many structural components are made of austenitic stainless steels (SS). These components are subject to extreme conditions, such as large temperature gradients and pressure loads during service. Hence, the fatigue and fracture behavior of austenitic SS under these conditions has evoked consistent interest over the years. Most studies dealing with this problem in the past, investigated the isothermal fatigue (IF) condition, which is not the case in the service, and less attention has been paid to thermomechanical fatigue (TMF). Moreover, the existing codes of practice and standards for TMF testing are mainly derived from the high temperature TMF tests ( T mean > 400 °C). This work presents the development of a facility to perform TMF tests under LWR relevant temperature interval in air. The realized testing parameters and tolerances are compared with the recommendations of existing codes of practice and standards from high temperature tests. The effectiveness of the testing facility was verified with series of TMF and IF tests performed on specimens made out of a commercial austenitic SS TP347 pipe material. The results revealed that the existing tolerances in standards are quite strict for the application of lower temperature ranges TMF tests. It was found that the synchronous, in-phase (IP) TMF tested specimens possess a higher lifetime than those subjected to the asynchronous, out-of-phase (OP) TMF and IF at T max in the investigated strain range for austenitic SS. Nevertheless, the fatigue lifetime of all the test conditions was similar in the engineering scale.

  16. 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.

  17. Numerical investigation of the propagation of light-induced detonation waves during the absorption of high-power laser radiation in air at elevated density

    NASA Astrophysics Data System (ADS)

    Pirogov, S. Yu.; Belyanin, D. G.; Yur'ev, A. S.; Tipaev, V. V.; Filatov, A. V.

    2010-12-01

    Spatiotemporal gasdynamic plasma structures formed in quiescent air of elevated density by high-power unfocused laser radiation absorbed in the light-induced detonation (LID) wave regime have been numerically studied using a model of inviscid, equilibrium emitting air. Laser radiation intensity and air density serve as parameters of the model. Dependences of the velocity of LID wave on the laser radiation intensity at elevated air densities are presented.

  18. 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...

  19. Probing the micellization kinetics of pyrene end-labeled diblock copolymer via a combination of stopped-flow light-scattering and fluorescence techniques.

    PubMed

    Zhang, Jingyan; Li, Yuting; Armes, Steven P; Liu, Shiyong

    2007-10-25

    A pyrene end-labeled double hydrophilic diblock copolymer, poly(2-(diethylamino)ethyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate) (Py-PDEA-b-PDMA), was synthesized by sequential monomer addition via oxyanionic polymerization using a 1-pyrenemethanol-based initiator. This diblock copolymer exhibits reversible pH-responsive micellization behavior in aqueous solution, forming PDEA-core micelles stabilized by the soluble PDMA block at neutral or alkaline pH. Taking advantage of the pyrene probe covalently attached to the end of the PDEA block, the pH-induced micellization kinetics of Py-PDEA-b-PDMA was monitored by stopped-flow light scattering using a fluorescence detector. Upon a pH jump from 4.0 to 9.0, both the scattered light intensity and excimer/monomer fluorescence intensity ratios (IE/IM) increase abruptly initially, followed by a more gradual increase to reach plateau values. Interestingly, the IE/IM ratio increases abruptly within the first 10 ms: a triple exponential function is needed to fit the corresponding dynamic trace, leading to three characteristic relaxation time constants (tau(1,fluo) < tau(2,fluo) < tau(3,fluo)). On the other hand, dynamic traces for the scattered light intensity can be well-fitted by double exponential functions: the resulting time constants tau(1,scat) and tau(2,scat) can be ascribed to formation of the quasi-equilibrium micelles and relaxation into their final equilibrium state, respectively. Most importantly, tau(1,scat) obtained from stopped-flow light scattering is in general agreement with tau(2,fluo) obtained from stopped-flow fluorescence. The fastest process (tau(1,fluo) approximately 4 ms) detected by stopped-flow fluorescence is ascribed to the burst formation of small transient micelles comprising only a few chains, which are too small to be detected by conventional light scattering. These nascent micelles undergo rapid fusion and grow into quasi-equilibrium micelles and then slowly approach their final

  20. 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.

  1. 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.

  2. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source.

    PubMed

    Pompidor, Guillaume; Dworkowski, Florian S N; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R

    2013-09-01

    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.

  3. 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

  4. Rational design, synthesis, and spectroscopic and photophysical properties of a visible-light-excitable, ratiometric, fluorescent near-neutral pH indicator based on BODIPY.

    PubMed

    Boens, Noël; Qin, Wenwu; Baruah, Mukulesh; De Borggraeve, Wim M; Filarowski, Aleksander; Smisdom, Nick; Ameloot, Marcel; Crovetto, Luis; Talavera, Eva M; Alvarez-Pez, Jose M

    2011-09-19

    A visible-light-excitable, ratiometric, brightly fluorescent pH indicator for measurements in the pH range 5-7 has been designed and synthesized by conjugatively linking the BODIPY fluorophore at the 3-position to the pH-sensitive ligand imidazole through an ethenyl bridge. The probe is available as cell membrane permeable methyl ester 8-(4-carbomethoxyphenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (I) and corresponding water-soluble sodium carboxylate, sodium 8-(4-carboxylatophenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (II). The fluorescence quantum yield Φ(f) of ester I is very high (0.8-1.0) in the organic solvents tested. The fluorescence lifetime (ca. 4 ns) of I in organic solvents with varying polarity/polarizability (from cyclohexane to acetonitrile) is independent of the solvent with a fluorescence rate constant k(f) of 2.4×10(8) s(-1). Probe I is readily loaded in the cytosol of live cells, where its high fluorescence intensity remains nearly constant over an extended time period. Water-soluble indicator II exhibits two acid-base equilibria in aqueous solution, characterized by pK(a) values of 6.0 and 12.6. The Φ(f) value of II in aqueous solution is high: 0.6 for the cationic and anionic forms of the imidazole ligand, and 0.8 for neutral imidazole. On protonation-deprotonation in the near-neutral pH range, UV/Vis absorption and fluorescence spectral shifts along with isosbestic and pseudo-isoemissive points are observed. This dual-excitation and dual-emission pH indicator emits intense green-yellow fluorescence at lower pH and intense orange fluorescence at higher pH. The influence of ionic strength and buffer concentration on the absorbance and steady-state fluorescence of II has also been investigated. The apparent pK(a) of the near-neutral acid-base equilibrium determined by spectrophotometric and fluorometric titration is nearly independent of

  5. 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.

  6. 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.

  7. Light

    NASA Astrophysics Data System (ADS)

    Vernon, C. G.

    2016-09-01

    Preface; 1. Historical; 2. Waves and wave-motion; 3. The behaviour of ripples; 4. The behaviour of light; 5. Refraction through glass blocks and prisms; 6. The imprinting of curvatures; 7. Simple mathematical treatment; 8. More advanced mathematical treatment; 9. The velocity of light; 10. The spectrum and colour; 11. Geometrical optics; 12. The eye and optical instruments; 13. Sources of light; 14. Interference, diffraction and polarisation; 15. Suggestions for class experiments; Index.

  8. 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.

  9. Above 20% external quantum efficiency in novel hybrid white organic light-emitting diodes having green thermally activated delayed fluorescent emitter

    PubMed Central

    Kim, Bo Seong; Yook, Kyoung Soo; Lee, Jun Yeob

    2014-01-01

    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. PMID:25317855

  10. Influence of dehydrated nanotubed titanic acid on charge transport and luminescent properties of polymer light-emitting diodes with fluorescent dye

    NASA Astrophysics Data System (ADS)

    Qian, Lei; Bera, Debasis; Jin, Zhen-Sheng; Du, Zu-Liang; Xu, Zheng; Teng, Feng; Liu, Wei

    2007-09-01

    In this paper, we discuss the influence of dehydrated nanotubed titanic acid (DNTA) on charge transport and luminescent properties of polymer light-emitting diodes (PLEDs) doped with fluorescent dye. Photoluminescence results confirm the efficient energy transfer from PVK to 4-(dicyanom-ethylene)-2- t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) and tris-(8-hydroxtquinoline) aluminum (Alq 3) in a DNTA-doped device. The device showed lower turn-on voltages and higher charge current by doping with DNTA, which also caused a shift in the exciton's recombination region.

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Barber, K. B.; Barbosa, A. F.; Barroso, S. L. C.; Baughman, B.; Bauleo, P.; Beatty, J. J.; Beau, T.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Chye, J.; Clay, R. W.; Colombo, E.; Conceição, R.; Contreras, F.; Cook, H.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; Di Giulio, C.; Diaz, J. C.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; DuVernois, M. A.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrer, F.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Goggin, L. M.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonzalez, D.; Gonzalez, J. G.; Góra, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Halenka, V.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Healy, M. D.; Hebbeker, T.; Hebrero, G.; Heck, D.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Hrabovský, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kasper, P.; Kégl, B.; Keilhauer, B.; Kelley, J.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Krieger, A.; Krömer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, K.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Lee, J.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; McNeil, R. R.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Morris, C.; Mostafá, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Newman-Holmes, C.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parlati, S.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Peķala, J.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Redondo, A.; Revenu, B.; Rezende, F. A. S.; Ridky, J.; Riggi, S.; Risse, M.; Rivière, C.; Rizi, V.; Robledo, C.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schroeder, F.; Schulte, S.; Schüssler, F.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Semikoz, D.; Settimo, M.; Shellard, R. C.; Sidelnik, I.; Siffert, B. B.; Sigl, G.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Tamashiro, A.; Tamburro, A.; Tarutina, T.; Taşcău, O.; Tcaciuc, R.; Tcherniakhovski, D.; Tegolo, D.; Thao, N. T.; Thomas, D.; Ticona, R.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Torres, I.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Velarde, A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Warner, D.; Watson, A. A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Winchen, T.; Winnick, M. G.; Wu, H.; Wundheiler, B.; Yamamoto, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Ziolkowski, M.; Pierre Auger Collaboration

    2010-03-01

    The air fluorescence detector of the Pierre Auger Observatory is designed to perform calorimetric measurements of extensive air showers created by cosmic rays of above 1018eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group of monitoring instruments to record atmospheric conditions across the detector site, an area exceeding 3000 km 2. The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierre Auger Observatory since the start of regular operations in 2004, and includes a discussion of the impact of these measurements on air shower reconstructions. Between 1018 and 1020eV, the systematic uncertainties due to all atmospheric effects increase from 4% to 8% in measurements of shower energy, and 4gcm to 8gcm in measurements of the shower maximum.

  18. An RNA-Seq Analysis of Grape Plantlets Grown in vitro Reveals Different Responses to Blue, Green, Red LED Light, and White Fluorescent Light

    PubMed Central

    Li, Chun-Xia; Xu, Zhi-Gang; Dong, Rui-Qi; Chang, Sheng-Xin; Wang, Lian-Zhen; Khalil-Ur-Rehman, Muhammad; Tao, Jian-Min

    2017-01-01

    Using an RNA sequencing (RNA-seq) approach, we analyzed the differentially expressed genes (DEGs) and physiological behaviors of “Manicure Finger” grape plantlets grown in vitro under white, blue, green, and red light. A total of 670, 1601, and 746 DEGs were identified in plants exposed to blue, green, and red light, respectively, compared to the control (white light). By comparing the gene expression patterns with the growth and physiological responses of the grape plantlets, we were able to link the responses of the plants to light of different spectral wavelengths and the expression of particular sets of genes. Exposure to red and green light primarily triggered responses associated with the shade-avoidance syndrome (SAS), such as enhanced elongation of stems, reduced investment in leaf growth, and decreased chlorophyll levels accompanied by the expression of genes encoding histone H3, auxin repressed protein, xyloglucan endotransglycosylase/hydrolase, the ELIP protein, and microtubule proteins. Furthermore, specific light treatments were associated with the expression of a large number of genes, including those involved in the glucan metabolic pathway and the starch and sucrose metabolic pathways; these genes were up/down-regulated in ways that may explain the increase in the starch, sucrose, and total sugar contents in the plants. Moreover, the enhanced root growth and up-regulation of the expression of defense genes accompanied with SAS after exposure to red and green light may be related to the addition of 30 g/L sucrose to the culture medium of plantlets grown in vitro. In contrast, blue light induced the up-regulation of genes related to microtubules, serine carboxypeptidase, chlorophyll synthesis, and sugar degradation and the down-regulation of auxin-repressed protein as well as a large number of resistance-related genes that may promote leaf growth, improve chlorophyll synthesis and chloroplast development, increase the ratio of chlorophyll a (chla

  19. An RNA-Seq Analysis of Grape Plantlets Grown in vitro Reveals Different Responses to Blue, Green, Red LED Light, and White Fluorescent Light.

    PubMed

    Li, Chun-Xia; Xu, Zhi-Gang; Dong, Rui-Qi; Chang, Sheng-Xin; Wang, Lian-Zhen; Khalil-Ur-Rehman, Muhammad; Tao, Jian-Min

    2017-01-01

    Using an RNA sequencing (RNA-seq) approach, we analyzed the differentially expressed genes (DEGs) and physiological behaviors of "Manicure Finger" grape plantlets grown in vitro under white, blue, green, and red light. A total of 670, 1601, and 746 DEGs were identified in plants exposed to blue, green, and red light, respectively, compared to the control (white light). By comparing the gene expression patterns with the growth and physiological responses of the grape plantlets, we were able to link the responses of the plants to light of different spectral wavelengths and the expression of particular sets of genes. Exposure to red and green light primarily triggered responses associated with the shade-avoidance syndrome (SAS), such as enhanced elongation of stems, reduced investment in leaf growth, and decreased chlorophyll levels accompanied by the expression of genes encoding histone H3, auxin repressed protein, xyloglucan endotransglycosylase/hydrolase, the ELIP protein, and microtubule proteins. Furthermore, specific light treatments were associated with the expression of a large number of genes, including those involved in the glucan metabolic pathway and the starch and sucrose metabolic pathways; these genes were up/down-regulated in ways that may explain the increase in the starch, sucrose, and total sugar contents in the plants. Moreover, the enhanced root growth and up-regulation of the expression of defense genes accompanied with SAS after exposure to red and green light may be related to the addition of 30 g/L sucrose to the culture medium of plantlets grown in vitro. In contrast, blue light induced the up-regulation of genes related to microtubules, serine carboxypeptidase, chlorophyll synthesis, and sugar degradation and the down-regulation of auxin-repressed protein as well as a large number of resistance-related genes that may promote leaf growth, improve chlorophyll synthesis and chloroplast development, increase the ratio of chlorophyll a (chla

  20. Directed Evolution of Key Residues in Fluorescent Protein Inverses the Polarity of Voltage Sensitivity in the Genetically Encoded Indicator ArcLight

    PubMed Central

    2017-01-01

    Genetically encoded calcium indicators (GECIs) produce unprecedentedly large signals that have enabled routine optical recording of single neuron activity in vivo in rodent brain. Genetically encoded voltage indicators (GEVIs) offer a more direct measure of neuronal electrical status, however the signal-to-noise characteristics and signal polarity of the probes developed to date have precluded routine use in vivo. We applied directed evolution to target modulable areas of the fluorescent protein in GEVI ArcLight to create the first GFP-based GEVI (Marina) that exhibits a ΔF/ΔV with a positive slope relationship. We found that only three rounds of site-directed mutagenesis produced a family of “brightening” GEVIs with voltage sensitivities comparable to that seen in the parent probe ArcLight. This shift in signal polarity is an essential first step to producing voltage indicators with signal-to-noise characteristics comparable to GECIs to support widespread use in vivo. PMID:28045247

  1. In vivo white light and contrast-enhanced vital-dye fluorescence imaging of Barrett's-related neoplasia in a single-endoscopic insertion

    NASA Astrophysics Data System (ADS)

    Tang, Yubo; Carns, Jennifer; Polydorides, Alexandros D.; Anandasabapathy, Sharmila; Richards-Kortum, Rebecca R.

    2016-08-01

    A modular video endoscope is developed to enable both white light imaging (WLI) and vital-dye fluorescence imaging (VFI) in a single-endoscopic insertion for the early detection of cancer in Barrett's esophagus (BE). We demonstrate that VFI can be achieved in conjunction with white light endoscopy, where appropriate white balance is used to correct for the presence of the emission filter. In VFI mode, a contrast enhancement feature is implemented in real time to further highlight glandular patterns in BE and related malignancies without introducing artifacts. In a pilot study, we demonstrate accurate correlation of images in two widefield modalities, with representative images showing the disruption and effacement of glandular architecture associated with cancer development in BE. VFI images of these alterations exhibit enhanced contrast when compared to WLI. Results suggest that the usefulness of VFI in the detection of BE-related neoplasia should be further evaluated in future in vivo studies.

  2. Determination of Ammonium in Aqueous Samples by Gas Phase Light Scattering Using Hydrogen Chloride Gas as a Derivatizing Reagent Followed by Nondispersive Atomic Fluorescence Spectrometry.

    PubMed

    Duan, Xuchuan; Fang, Jinliang; Sun, Rui

    2017-01-01

    A sensitive method was developed for the determination of ammonium in an aqueous solution based on gas phase light scattering. In a stream of carrier gas, the gaseous ammonia from the alkalized solution formed a volatile ammonium chloride derivative by reacting with gaseous hydrogen chloride; the gaseous ammonium chloride was analyzed by nondispersive atomic fluorescence spectrometry. The mechanisms of the method are elucidated based on evaporative light scattering detection. Parameters such as temperature, amount of sodium hydroxide, and carrier gas flow rate were studied. Under optimal conditions, the detection limit of ammonium-nitrogen was 0.045 μg. The method was successfully applied to the determination of ammonium in certified reference materials, and tap and seawater samples.

  3. Directed Evolution of Key Residues in Fluorescent Protein Inverses the Polarity of Voltage Sensitivity in the Genetically Encoded Indicator ArcLight.

    PubMed

    Platisa, Jelena; Vasan, Ganesh; Yang, Amy; Pieribone, Vincent A

    2017-02-02

    Genetically encoded calcium indicators (GECIs) produce unprecedentedly large signals that have enabled routine optical recording of single neuron activity in vivo in rodent brain. Genetically encoded voltage indicators (GEVIs) offer a more direct measure of neuronal electrical status, however the signal-to-noise characteristics and signal polarity of the probes developed to date have precluded routine use in vivo. We applied directed evolution to target modulable areas of the fluorescent protein in GEVI ArcLight to create the first GFP-based GEVI (Marina) that exhibits a ΔF/ΔV with a positive slope relationship. We found that only three rounds of site-directed mutagenesis produced a family of "brightening" GEVIs with voltage sensitivities comparable to that seen in the parent probe ArcLight. This shift in signal polarity is an essential first step to producing voltage indicators with signal-to-noise characteristics comparable to GECIs to support widespread use in vivo.

  4. Molecular architecture in cyanine dye aggregates at the air-water interface. Effect of monolayer composition and organization on fluorescent behavior

    SciTech Connect

    Vaidyanathan, S.; Patterson, L.K.; Moebius, D.; Gruniger, H.R.

    1985-01-31

    The fluorescence behavior of an amphiphatic oxacyanine dye and its thiacyanine analogue has been investigated in spread monolayers at the air-water interface. J-aggregate formation as a function of area/(dye molecule) was monitored by spectral changes in pure dye monolayers and in 1:1 mixtures of dye with various fatty acid coaggregates. Simultaneously, the thermodynamic behavior of these systems was characterized by the associated surface pressure-area isotherms. In all cases, J-aggregate formation may be related to a phase transition in the isotherm. The intensity of aggregate fluorescence is found to be inversely related to the work, ..delta..W, of compression of the monolayer through the transition. Inclusion of the fatty acid coaggregate was shown to facilitate J-aggregate formation in the order stearic > elaidic > oleic. Both fluorescence and thermodynamic data indicate more extensive aggregate formation in the thiacyanine systems. Aside from the paramount role played by the chromophore-chromophore interactions in determining J-aggregate phenomena, this study suggests important contributions from dispersion forces involving the long hydrocarbon moieties. 13 refs., 10 figs.

  5. FLUORESCENCE EMISSION SPECTRA OF MARINE AND BRACKISH-WATER ECOTYPES OF FUCUS VESICULOSUS AND FUCUS RADICANS (PHAEOPHYCEAE) REVEAL DIFFERENCES IN LIGHT-HARVESTING APPARATUS(1).

    PubMed

    Maria Gylle, Anna; Rantamäki, Susanne; Ekelund, Nils G A; Tyystjärvi, Esa

    2011-02-01

    The Bothnian Sea in the northerly part of the Baltic Sea is a geologically recent brackish-water environment, and rapid speciation is occurring in the algal community of the Bothnian Sea. We measured low-temperature fluorescence emission spectra from the Bothnian Sea and the Norwegian Sea ecotypes of Fucus vesiculosus L., a marine macroalga widespread in the Bothnian Sea. Powdered, frozen thallus was used to obtain undistorted emission spectra. The spectra were compared with spectra measured from the newly identified species Fucus radicans Bergström et L. Kautsky, which is a close relative of F. vesiculosus and endemic to the Bothnian Sea. The spectrum of variable fluorescence was used to identify fluorescence peaks originating in PSI and PSII in this chl c-containing alga. The spectra revealed much higher PSII emission, compared to PSI emission, in the Bothnian Sea ecotype of F. vesiculosus than in F. radicans or in the Norwegian Sea ecotype of F. vesiculosus. The results suggest that more light-harvesting chl a/c proteins serve PSII in the Bothnian Sea ecotype of F. vesiculosus than in the two other algal strains. Treatment of the Bothnian Sea ecotype of F. vesiculosus in high salinity (10, 20, and 35 practical salinity units) for 1 week did not lead to spectral changes, indicating that the measured features of the Bothnian Sea F. vesiculosus are stable and not simply a direct result of exposure to low salinity.

  6. Binding investigation on the interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin by resonance light-scattering (RLS) technique and fluorescence spectroscopy.

    PubMed

    Li, Yuesheng; Zhang, Yue; Sun, Shaofa; Zhang, Aiqing; Liu, Yi

    2013-11-05

    The interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin (BSA) was investigated by resonance light scattering (RLS), fluorescence, three-dimension spectra and UV-vis absorbance spectroscopy. Several factors which may influence the RLS intensity were also investigated before characterizing MB/TiO2-BSA complex. It was proved that the mechanism of MB/TiO2 nanocomposites binding to BSA was mainly a result of the formation of MB/TiO2-BSA complex. The binding constant of MB/TiO2-BSA is 0.762 × 10(-5) L mol(-1) at 298K. By calculating the binding constant at different temperature, the thermodynamic parameters ΔH, ΔG, and ΔS can be observed and deduced that the hydrophobic interactions played an important role to stabilize the complex. The distance r (3.73 nm) between donor (BSA) and acceptor (MB/TiO2) was obtained according to fluorescence resonance energy transfer (FRET). The binding site for MB/TiO2 on BSA was mainly located in sub-domain IIA. The UV-vis absorbance, circular dichroism and three dimension fluorescence have also been used to investigate the effect of MB/TiO2 on the conformation of BSA.

  7. 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

    2016-08-07

    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.

  8. STAR Measurements and Modeling for Quantifying Air Quality and Climatic Impacts of Residential Biomass or Coal Combustion for Cooking, Heating and Lighting Kick-off Meeting

    EPA Pesticide Factsheets

    STAR grantees and EPA scientists will discuss progress on their projects which aim to quantify the extent to which interventions for cleaner cooking, heating, or lighting can impact air quality and climate, which in turn affect human health and welfare

  9. 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.

  10. Bioluminescent liquid light guide pad biosensor for indoor air toxicity monitoring.

    PubMed

    Eltzov, Evgeni; Cohen, Avital; Marks, Robert S

    2015-04-07

    Indoor air pollution became a recent concern found to be oftentimes worse than outdoor air quality. We developed a tool that is cheap and simple and enables continuous monitoring of air toxicity. It is a biosensor with both a nondisposable (monitor) and disposable (calcium alginate pads with immobilized bacteria) elements. Various parameters to enhance its signal have been tested (including the effect of the pad's orientation, it's exposure to either temperature or time with the air toxicant analyte, and various concentrations thereof). Lastly, the sensor has demonstrated its ability to sense the presence of chemicals in a real, indoor environment. This is the first step in the creation of a sensitive and simple operative tool that may be used in different indoor environments.

  11. Size-fractionated sampling and chemical analysis by total-reflection X-ray fluorescence spectrometry of PMx in ambient air and emissions

    NASA Astrophysics Data System (ADS)

    John, A. C.; Kuhlbusch, T. A. J.; Fissan, H.; Schmidt, K.-G.

    2001-11-01

    PM 10 and PM 2.5 (PMx) have been recently introduced as new air quality standards in the EU (Council Directive 1999/30/EC) for particulate matter. Different estimates and measurements showed that the limit values for PM 10 will be exceeded at different locations in Europe, and thus measures will have to be taken to reduce PMx mass concentrations. Source apportionment has to be carried out, demanding comparable methods for ambient air and emission sampling and chemical analysis. Therefore, a special ambient-air sampler and a specially designed emission sampler have been developed. Total-reflection X-ray fluorescence analysis (TXRF) was used for multi-element analyses as a fast method with low detection limits. For ambient air measurements, a sampling unit was built, impacting particle size classes 10-2.5 μm and 2.5-1.0 μm directly onto TXRF sample carriers. An electrostatic precipitator (ESP) was used as back-up filter to also collect particles <1 μm directly onto the TXRF sample carriers. Air quality is affected by natural and anthropogenic sources, and the emissions of particles <10 μm and <2.5 μm, respectively, have to be determined to quantify their contributions to the so-called coarse (10-2.5 μm) and fine (<2.5 μm) particle modes in ambient air. For this, an in-stack particle sampling system was developed, according to the new ambient air quality standards and in view of subsequent analysis by TXRF. These newly developed samplers, in combination with TXRF analyses, were employed in field campaigns to prove the feasibility and capabilities of the approach. Ambient air data show the quantification of a wide spectrum of elements. From those concentrations, PMx ratios were calculated as an indicator for different sources of elements. Results useful for source apportionment are also the elemental day/night ratios calculated to determine local contributions to PMx mass concentrations. With regard to the emission measurements, results of mass and elemental

  12. Chemical bonding of chlorophylls and plant aminic axial ligands impact harvesting of visible light and quenching of fluorescence.

    PubMed

    Ioannidis, Nikolaos E; Tsiavos, Theodoros; Kotzabasis, Kiriakos

    2012-01-01

    In the present work, we tested the mode of interaction of all three polyamines (putrescine, spermidine and spermine) with chlorophyll a and b, as well as pheophytin a and b. The results showed that all three polyamines bind to the Mg ion of chlorophyll ring as probed by Raman spectroscopy. The coordination of spermine with Chl b has the most interesting features from all pigments tested. Spermine induces reversible increases and decreases of the fluorescence yield of Chl b at about 661 nm. Interestingly, equilibrium between a high-fluorescence yield conformation and a low yield is feasible by the interaction of chlorophyll b and aminic ligands. Furthermore, absorption data for the diagnostic regions of 518 and 535 nm are provided for all combinations of pigments and ligands. The significance and consistence of these results with respect to photochemical and bioenergetic principles are discussed.

  13. Whole column fluorescence imaging on a microchip by using a programmed organic light emitting diode array as a spatial-scanning light source and a single photomultiplier tube as detector.

    PubMed

    Ren, Kangning; Liang, Qionglin; Yao, Bo; Luo, Guoan; Wang, Liduo; Gao, Yudi; Wang, Yiming; Qiu, Yong

    2007-11-01

    A novel miniaturized, integrated whole-column imaging detection (WCID) system on a microchip is presented. In this system, a program controlled organic light emitting diode (OLED) array was used as a spatial-scanning light source, to achieve imaging by the time sequence of the excited fluorescence. By this mechanism, a photomultiplier tube (PMT) instead of a charge coupled detector (CCD) can be applied to the imaging. Unlike conventional systems, no lenses, fibers or any mechanical components are required either. The novel flat light source provides uniform excitation light without size limitations and outputs a stronger power by pulse driving. The scanning mode greatly reduced the power consumption of the light source, which is valuable for a portable system. Meanwhile, this novel simplified system has a broader linear range, higher sensitivity and higher efficiency in data collection. Isoelectric focusing of R-phycoerythrin (PE) and monitoring of the overall process with WCID were performed on this system. The limit of detection (LOD) was 38 ng mL(-1) or 3.2 pg at 85 nL per column injection of PE. The system provides a technique for WCID capillary isoelectric focusing (cIEF) on chip and can be used for throughput analysis.

  14. 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.

  15. 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.

  16. Analysis of waveguide-coupled directional emission for efficient collection of Fluorescence/Raman light from surface

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Lu, Dan-Feng; Gao, Ran; Qi, Zhi-Mei

    2016-05-01

    A theoretical method based on the optical reciprocity theorem combined with the Fresnel theory has been developed for the analysis of waveguide-coupled directional emission technique, which is useful for the surface Fluorescence/Raman spectroscopy. The Kretschmann-type waveguide with a molecular dipole located above or inside the core layer serves as the simulation model. The two-dimensional (2D) pattern of power density for the waveguide-coupled emission from the molecular dipole was calculated using the theoretical method. According to the results, with a given waveguide the 2D pattern of power density is highly dependent on both the orientation and position of the dipole. The maximum fraction of power occupied by the waveguide-coupled emission is 87% with the plasmon waveguide and 95% with the resonant mirror. Compared with the dipole emission in free space, the waveguide-coupled directional emission possesses easy collection, which is benefit for the detection of weak Fluorescence and Raman signals. From this point, the theoretical method used here is helpful for design and optimization of Kretschmann-type waveguide structures for high-sensitivity surface monitoring by Fluorescence/Raman spectroscopy.

  17. Fluorescence-guided surgery of retroperitoneal-implanted human fibrosarcoma in nude mice delays or eliminates tumor recurrence and increases survival compared to bright-light surgery.

    PubMed

    Uehara, Fuminari; Hiroshima, Yukihiko; Miwa, Shinji; Tome, Yasunori; Yano, Shuya; Yamamoto, Mako; Matsumoto, Yasunori; Maehara, Hiroki; Tanaka, Kazuhiro; Bouvet, Michael; Kanaya, Fuminori; Hoffman, Robert M

    2015-01-01

    The aim of this study is to determine if fluorescence-guided surgery (FGS) can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP) (HT-1080-GFP), in nude mice, bright-light surgery (BLS) was performed on all tumor-bearing mice (n = 22). After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11) or the combination of BLS + FGS (n = 11). The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm(2) and 10.5 ± 2.4 mm(2), respectively; p = 0.006). Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm(2) and 11.7 ± 6.9 mm(2), respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001). Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.

  18. Photocatalytic performance of electrospun CNT/TiO2 nanofibers in a simulated air purifier under visible light irradiation.

    PubMed

    Wongaree, Mathana; Chiarakorn, Siriluk; Chuangchote, Surawut; Sagawa, Takashi

    2016-11-01

    The photocatalytic treatment of gaseous benzene under visible light irradiation was developed using electrospun carbon nanotube/titanium dioxide (CNT/TiO2) nanofibers as visible light active photocatalysts. The CNT/TiO2 nanofibers were fabricated by electrospinning CNT/poly(vinyl pyrrolidone) (PVP) solution followed by the removal of PVP by calcination at 450 °C. The molar ratio of CNT/TiO2 was fixed at 0.05:1 by weight, and the quantity of CNT/TiO2 loaded in PVP solution varied between 30 and 60 % wt. CNT/TiO2 nanofibers have high specific surface area (116 m(2)/g), significantly higher than that of TiO2 nanofibers (44 m(2)/g). The photocatalytic performance of the CNT/TiO2 nanofibers was investigated by decolorization of 1 × 10(-5) M methylene blue (MB) dye (in water solution) and degradation of 100 ppm gaseous benzene under visible light irradiation. The 50-CNT/TiO2 nanofibers (calcined CNT/TiO2 nanofibers fabricated from a spinning solution of 50 % wt CNT/TiO2 based on PVP) had higher MB degradation efficiency (58 %) than did other CNT/TiO2 nanofibers and pristine TiO2 nanofibers (15 %) under visible light irradiation. The photocatalytic degradation of gaseous benzene under visible light irradiation on filters made of 50-CNT/TiO2 nanofibers was carried out in a simulated air purifier system. Similar to MB results, the degradation efficiency of gaseous benzene by 50-CNT/TiO2 nanofibers (52 %) was higher than by other CNT/TiO2 nanofibers and pristine TiO2 nanofibers (18 %). The synergistic effects of the larger surface area and lower band gap energy of CNT/TiO2 nanofibers were presented as strong adsorption ability and greater visible light adsorption. The CNT/TiO2 nanofiber prepared in this study has potential for use in air purifiers to improve air treatment efficiency with less energy.

  19. 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.

  20. Fluorescent fiber diagnostics

    DOEpatents

    Toeppen, John S.

    1994-10-04

    A fluorescent fiber (13) having a doped core (16) is pumped (11) by light (18) of a relatively short wavelength to produce fluorescence at a longer wavelength that is detected by detector (24). The level of fluorescence is monitored (26) and evaluated to provide information as to the excitation of the fiber (13) or the environment thereof. In particular, the level of intensity of the detected fluorescence may be used to measure the intensity of a light beam (18) passing axially through an optical fiber system (12) (FIG. 1 ), or the intensity of a light beam (46) passing radially through a fluorescent fiber (13) (FIG. 2 ), or the level of a fluid (32) in a tank (31) (FIG. 3 ), or a scintillation event (37) in a fluorescent fiber (13) pumped to produce amplification of the scintillation event (FIG. 4 ).

  1. Fluorescent fiber diagnostics

    DOEpatents

    Toeppen, John S.

    1994-01-01

    A fluorescent fiber (13) having a doped core (16) is pumped (11) by light (18) of a relatively short wavelength to produce fluorescence at a longer wavelength that is detected by detector (24). The level of fluorescence is monitored (26) and evaluated to provide information as to the excitation of the fiber (13) or the environment thereof. In particular, the level of intensity of the detected fluorescence may be used to measure the intensity of a light beam (18) passing axially through an optical fiber system (12) (FIG. 1 ), or the intensity of a light beam (46) passing radially through a fluorescent fiber (13) (FIG. 2 ), or the level of a fluid (32) in a tank (31) (FIG. 3 ), or a scintillation event (37) in a fluorescent fiber (13) pumped to produce amplification of the scintillation event (FIG. 4 ).

  2. Responsive polymer-fluorescent carbon nanoparticle hybrid nanogels for optical temperature sensing, near-infrared light-responsive drug release, and tumor cell imaging

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Ke, Fuyou; Mararenko, Anton; Wei, Zengyan; Banerjee, Probal; Zhou, Shuiqin

    2014-06-01

    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.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

  3. Graphene based silicon-air grating structure to realize electromagnetically-induced-transparency and slow light effect

    NASA Astrophysics Data System (ADS)

    Wei, Buzheng; Liu, Huaiqing; Ren, Guobin; Yang, Yuguang; Ye, Shen; Pei, Li; Jian, Shuisheng

    2017-01-01

    A broad band tunable graphene based silicon-air grating structure is proposed. Electromagnetically-induced-transparency (EIT) window can be successfully tuned by virtually setting the desired Fermi energy levels on graphene sheets. Carrier mobility plays an important role in modulating the resonant depth. Furthermore, by changing the grating periods, light can be trapped at corresponding resonant positions where slow down factor is relatively larger than in the previous works. This structure can be used as a highly tunable optoelectronic device such as optical filter, broad-band modulator, plasmonic switches and buffers.

  4. Angularly symmetric splitting of a light beam upon reflection and refraction at an air-dielectric plane boundary: comment.

    PubMed

    Andersen, Torben B

    2016-05-01

    In a recent paper, conditions for achieving equal and opposite angular deflections of a light beam by reflection and refraction at an interface between air and a dielectric were determined [J. Opt. Soc. Am. A32, 2436 (2015)JOAOD60740-323210.1364/JOSAA.32.002436]. The paper gives plots of angles of incidence and refraction as a function of the prism refractive index as well as plots of reflectances and incident linear-polarization azimuth angles as functions of the refractive index. We show here that it is possible to express these quantities as simple algebraic functions of the refractive index.

  5. Wideband and low dispersion slow-light waveguide based on a photonic crystal with crescent-shaped air holes.

    PubMed

    Meng, Bo; Wang, Ling-ling; Huang, Wei-qing; Li, Xiao-fei; Zhai, Xiang; Zhang, Hong

    2012-08-10

    We present a procedure to generate slow light with a large group index, wideband, and low dispersion in our suggested photonic crystal waveguide. By modulation of the declinations in the first two rows of air holes, the group index, the bandwidth, and the dispersion can be tuned effectively. Utilizing the two-dimensional plane wave expansion method (PWE) and the finite-difference time-domain method (FDTD), we demonstrate slow light with the group indices of 23, 35, and 45, respectively, while restricting the group-index variation within a 10% range. We accordingly attain an available bandwidth of 40.7, 23.7, and 5.1 nm, respectively. Meanwhile, the normalized delay-bandwidth product stays around 0.45, with minimal dispersion less than 0.2 (ps2/m) for all the cases.

  6. Angularly symmetric splitting of a light beam upon reflection and refraction at an air-dielectric plane boundary.

    PubMed

    Azzam, R M A

    2015-12-01

    Conditions for achieving equal and opposite angular deflections of a light beam by reflection and refraction at an air-dielectric boundary are determined. Such angularly symmetric beam splitting (ASBS) is possible only if the angle of incidence is >60° by exactly one third of the angle of refraction. This simple law, plus Snell's law, leads to several analytical results that clarify all aspects of this phenomenon. In particular, it is shown that the intensities of the two symmetrically deflected beams can be equalized by proper choice of the prism refractive index and the azimuth of incident linearly polarized light. ASBS enables a geometrically attractive layout of optical systems that employ multiple prism beam splitters.

  7. Near-Infrared Light Triggered ROS-activated Theranostic Platform based on Ce6-CPT-UCNPs for Simultaneous Fluorescence Imaging and Chemo-Photodynamic Combined Therapy

    PubMed Central

    Yue, Caixia; Zhang, Chunlei; Alfranca, Gabriel; Yang, Yao; Jiang, Xinquan; Yang, Yuming; Pan, Fei; de la Fuente, Jesús M.; Cui, Daxiang

    2016-01-01

    Many drug controlled release methods have been integrated in multifunctional nanoparticles, such as pH-, redox-, temperature-, enzyme-, and light-responsive release. However, few report is associated with the ROS responsive drug controlled release. Herein, a thioketal linker-based ROS responsive drug (camptothecin conjugated with thioketal linker, abbreviated as TL-CPT) was prepared and the thioketal linker could be cleaved by ROS(reactive oxygen species). To achieve cancer simultaneous optical imaging, photodynamic therapy and chemotherapy, the photosensitizer Chlorin e6(Ce6), TL-CPT and carboxyl-mPEG were loaded on the upconversion nanoparticles (UCNPs), which were named as Ce6-CPT-UCNPs. Under 980 nm laser irradiation, Ce6-CPT-UCNPs emitted a narrow emission band at 645-675 nm which was overlapped with Ce6 absorption peak. Ce6 absorbed the light to produce ROS, which was used for photodynamic therapy and to cleave the thioketal linker in Ce6-CPT-UCNPs to release camptothecin for chemotherapy. Meanwhile, Ce6 absorbed the light, was used for near-infrared fluorescence imaging. The in vivo biodistribution studies showed that the prepared nanoparticles had high orthotopic lung cancer targeting efficiency. The in vivo therapeutic results demonstrated that NCI-H460 lung cancers could be completely eliminated by combining chemo- and photodynamic therapy under 980 nm laser irradiation. The prepared multifunctional Ce6-CPT-UCNPs have great potential in applications such as cancer targeted fluorescent imaging, simultaneous ROS activated chemo- and photodynamic therapy in near future. PMID:26941840

  8. Near-Infrared Light Triggered ROS-activated Theranostic Platform based on Ce6-CPT-UCNPs for Simultaneous Fluorescence Imaging and Chemo-Photodynamic Combined Therapy.

    PubMed

    Yue, Caixia; Zhang, Chunlei; Alfranca, Gabriel; Yang, Yao; Jiang, Xinquan; Yang, Yuming; Pan, Fei; de la Fuente, Jesús M; Cui, Daxiang

    2016-01-01

    Many drug controlled release methods have been integrated in multifunctional nanoparticles, such as pH-, redox-, temperature-, enzyme-, and light-responsive release. However, few report is associated with the ROS responsive drug controlled release. Herein, a thioketal linker-based ROS responsive drug (camptothecin conjugated with thioketal linker, abbreviated as TL-CPT) was prepared and the thioketal linker could be cleaved by ROS(reactive oxygen species). To achieve cancer simultaneous optical imaging, photodynamic therapy and chemotherapy, the photosensitizer Chlorin e6(Ce6), TL-CPT and carboxyl-mPEG were loaded on the upconversion nanoparticles (UCNPs), which were named as Ce6-CPT-UCNPs. Under 980 nm laser irradiation, Ce6-CPT-UCNPs emitted a narrow emission band at 645-675 nm which was overlapped with Ce6 absorption peak. Ce6 absorbed the light to produce ROS, which was used for photodynamic therapy and to cleave the thioketal linker in Ce6-CPT-UCNPs to release camptothecin for chemotherapy. Meanwhile, Ce6 absorbed the light, was used for near-infrared fluorescence imaging. The in vivo biodistribution studies showed that the prepared nanoparticles had high orthotopic lung cancer targeting efficiency. The in vivo therapeutic results demonstrated that NCI-H460 lung cancers could be completely eliminated by combining chemo- and photodynamic therapy under 980 nm laser irradiation. The prepared multifunctional Ce6-CPT-UCNPs have great potential in applications such as cancer targeted fluorescent imaging, simultaneous ROS activated chemo- and photodynamic therapy in near future.

  9. New light on a dark subject: On the use of fluorescence data to deduce redox states of natural organic matter (NOM)

    USGS Publications Warehouse

    Macalady, Donald L.; Walton-Day, Katherine

    2009-01-01

    This paper reports the use of excitation-emission matrix fluorescence spectroscopy (EEMS), parallel factor statistical analysis (PARAFAC), and oxidation-reduction experiments to examine the effect of redox conditions on PARAFAC model results for aqueous samples rich in natural organic matter. Fifty-four aqueous samples from 11 different geographic locations and two plant extracts were analyzed untreated and after chemical treatments or irradiation were used in attempts to change the redox status of the natural organic matter. The EEMS spectra were generated and modeled using a PARAFAC package developed by Cory and McKnight (2005). The PARAFAC model output was examined for consistency with previously reported relations and with changes expected to occur upon experimental oxidation and reduction of aqueous samples. Results indicate the implied fraction of total sample fluorescence attributed to quinone-like moieties was consistent (0.64 to 0.78) and greater than that observed by Cory and McKnight (2005). The fraction of the quinone-like moieties that was reduced (the reducing index, RI) showed relatively little variation (0.46 to 0.71) despite attempts to alter the redox status of the natural organic matter. The RI changed little after reducing samples using zinc metal, oxidizing at high pH with air, or irradiating with a Xenon lamp. Our results, however, are consistent with the correlations between the fluorescence indices (FI) of samples and the ratio of PARAFAC fitting parameters suggested by Cory and McKnight (2005), though we used samples with a much narrower range of FI values.

  10. [Two-photon excitation fluorescence spectrum of the light-harvesting complex LH2 from Chromatium minutissimum within 650-745 nm range is determined by two-photon absorption of bacteriochlorophyll rather than of carotenoids].

    PubMed

    Krikunova, M A; Leupold, D; Rini, M; Voigt, B; Moskalenko, A A; Toropygina, O A; Razzhivin, A P

    2002-01-01

    Two-photon fluorescence excitation spectra of the peripheral light-harvesting complex LH2 from the purple photosynthetic bacterium Chromatium minutissimum were examined within the expected spectral range of the optically forbidden S1 singlet state of carotenoids. LH2 preparations isolated from wild-type and carotenoid-depleted cells were used. 100-fs laser pulses in the range of 1300-1490 nm with an energy of 7-9 mW (corresponding to one-photon absorption between 650 and 745 nm) were used for two-photon fluorescence excitation. It was shown that two-photon fluorescence excitation spectra of LH2 complex from wild and carotenoid-depleted cells are very similar to each other and to the two-photon fluorescence excitation spectrum of bacteriochlorophyll a in acetone. It was concluded that direct two-photon excitation of bacteriochlorophyll a determines the fluorescence of both samples within the 650-745 nm spectral range.

  11. High Brightness Fluorescent White Polymer Light-Emitting Diodes by Promoted Hole Injection via Reduced Barrier by Interfacial Dipole Imparted from Chlorinated Indium Tin Oxide to the Hole Injection Layer PEDOT:PSS.

    PubMed

    Syue, Hong-Ren; Hung, Miao-Ken; Chang, Yao-Tang; Lin, Ge-Wei; Lee, Yu-Hsuan; Chen, Show-An

    2017-02-01

    We demonstrated that introducing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as a hole transport layer (HTL) on top of chlorinated indium tin oxide (Cl-ITO) anode can lead to a deeper highest occupied molecular orbital level of the HTL (promoting from 5.22 to 5.42 eV) due to the interfacial dipole imparted by the Cl-ITO, which allows barrier-free hole injection to the emitting layer with polyspirobifluorene doped with the yellow emitter rubrene and significantly prevents excitons quenching by residual chlorine radicals on the surface of Cl-ITO. By use of poly[9,9-bis(6'-(18-crown-6)methoxy)hexyl)fluorene] chelating to potassium ion (PFCn6:K(+)) as electron injection layer and air-stable high work function (EΦ) metal aluminum as the cathode, the performance of fluorescent white polymer light-emitting diode (WPLED) achieves the high maximum brightness (Bmax) of 61 523 cd/m(2) and maximum luminance efficiency (ηL, max) of 10.3 cd/A. Replacing PFCn6:K(+)/Al cathode by CsF/Al, the Bmax and ηL, max are promoted to 87 615 cd/m(2) (the record value in WPLED) and 11.1 cd/A, respectively.

  12. Seeing the light: the effects of particles, dissolved materials, and temperature on in situ measurements of DOM fluorescence in rivers and streams

    USGS Publications Warehouse

    Downing, Bryan D.; Pellerin, Brian A.; Bergamaschi, Brian A.; Saraceno, John Franco; Kraus, Tamara E.C.

    2012-01-01

    Field-deployable sensors designed to continuously measure the fluorescence of colored dissolved organic matter (FDOM) in situ are of growing interest. However, the ability to make FDOM measurements that are comparable across sites and over time requires a clear understanding of how instrument characteristics and environmental conditions affect the measurements. In particular, the effects of water temperature and light attenuation by both colored dissolved material and suspended particles may be significant in settings such as rivers and streams. Using natural standard reference materials, we characterized the performance of four commercially-available FDOM sensors under controlled laboratory conditions over ranges of temperature, dissolved organic matter (DOM) concentrations, and turbidity that spanned typical environmental ranges. We also examined field data from several major rivers to assess how often attenuation artifacts or temperature effects might be important. We found that raw (uncorrected) FDOM values were strongly affected by the light attenuation that results from dissolved substances and suspended particles as well as by water temperature. Observed effects of light attenuation and temperature agreed well with theory. Our results show that correction of measured FDOM values to account for these effects is necessary and feasible over much of the range of temperature, DOM concentration, and turbidity commonly encountered in surface waters. In most cases, collecting high-quality FDOM measurements that are comparable through time and between sites will require concurrent measurements of temperature and turbidity, and periodic discrete sample collection for laboratory measurement of DOM.

  13. Note: A laser-flash photolysis and laser-induced fluorescence detection technique for measuring total HO2 reactivity in ambient air

    NASA Astrophysics Data System (ADS)

    Miyazaki, K.; Nakashima, Y.; Schoemaecker, C.; Fittschen, C.; Kajii, Y.

    2013-07-01

    A novel instrument for measuring total HO2 reactivity in the troposphere was successfully developed using a laser-flash photolysis and laser-induced fluorescence detection technique. Validation and testing were conducted through kinetic measurements of the reaction of HO2 radicals with NO2, and the results were found to be in good agreement with recent recommended values. The limit of detection (LOD) for HO2 loss rate measurement is achieved to be 0.024 s-1 (3σ) with 60 times decay integrations. An observation of ambient air was carried out in a suburb of Tokyo to test the practical use of the developed instrument and un-expected rapid HO2 loss rate has been observed.

  14. Efficient fluorescence/phosphorescence white organic light-emitting diodes with ultra high color stability and mild efficiency roll-off

    NASA Astrophysics Data System (ADS)

    Du, Xiaoyang; Tao, Silu; Huang, Yun; Yang, Xiaoxia; Ding, Xulin; Zhang, Xiaohong

    2015-11-01

    Efficient fluorescence/phosphorescence hybrid white organic light-emitting diodes (OLEDs) with single doped co-host structure have been fabricated. Device using 9-Naphthyl-10 -(4-triphenylamine)anthrancene as the fluorescent dopant and Ir(ppy)3 and Ir(2-phq)3 as the green and orange phosphorescent dopants show the luminous efficiency of 12.4% (17.6 lm/W, 27.5 cd/A) at 1000 cd/m2. Most important to note that the efficiency-brightness roll-off of the device was very mild. With the brightness rising up to 5000 and 10 000 cd/m2, the efficiency could be kept at 11.8% (14.0 lm/W, 26.5 cd/A) and 11.0% (11.8 lm/W, 25.0 cd/A). The Commission Internationale de L'Eclairage (CIE) coordinates and color rending index (CRI) were measured to be (0.45, 0.48) and 65, respectively, and remained the same in a large range of brightness (1000-10 000 cd/m2), which is scarce in the reported white OLEDs. The performance of the device at high luminance (5000 and 10 000 cd/m2) was among the best reported results including fluorescence/phosphorescence hybrid and all-phosphorescent white OLEDs. Moreover, the CRI of the white OLED can be improved to 83 by using a yellow-green emitter (Ir(ppy)2bop) in the device.

  15. Lighting the Way to Protein-Protein Interactions: Recommendations on Best Practices for Bimolecular Fluorescence Complementation Analyses[OPEN

    PubMed Central

    Kudla, Jörg

    2016-01-01

    Techniques to detect and verify interactions between proteins in vivo have become invaluable tools in functional genomic research. While many of the initially developed interaction assays (e.g., yeast two-hybrid system and split-ubiquitin assay) usually are conducted in heterologous systems, assays relying on bimolecular fluorescence complementation (BiFC; also referred to as split-YFP assays) are applicable to the analysis of protein-protein interactions in most native systems, including plant cells. Like all protein-protein interaction assays, BiFC can produce false positive and false negative results. The purpose of this commentary is to (1) highlight shortcomings of and potential pitfalls in BiFC assays, (2) provide guidelines for avoiding artifactual interactions, and (3) suggest suitable approaches to scrutinize potential interactions and validate them by independent methods. PMID:27099259

  16. Non-dispersive atomic-fluorescence spectrometry of trace amounts of bismuth by introduction of its gaseous hydride into a premixed argon (entrained air)-hydrogen flame.

    PubMed

    Kobayashi, S; Nakahara, T; Musha, S

    1979-10-01

    A method has been developed for the determination of bismuth by generation of its gaseous hydride and introduction of the hydride into a premixed argon (entrained air)-hydrogen flame, the atomic-fluorescence lines from which are all detected by use of a non-dispersive system. The detection limit is 5 pg/ml, or 0.1 ng of bismuth, but the reagent blank found in a 20-ml sample volume was approximately 2 ng of bismuth. Analytical working curves obtained by measuring peak-heights and integrated peak-areas of the signals are linear over a range of about four orders of magnitude from the detection limit. Perchloric, phosphoric and sulphuric acids up to 2.0M concentration give no interference, but nitric acid gives slight depression of the signal. The presence of silver, gold, nickel, palladium, platinum, selenium and tellurium in 1000-fold ratio to bismuth causes pronounced depression of the signal, whereas mercury and tin slightly enhance the atomic-fluorescence signal. The method has been applied to the determination of bismuth in aluminium-base alloys and sulphide ores with use of the standard additions method. The results are in good agreement with those obtained by flame atomic-absorption spectrometry and optical emission spectrometry with an inductively coupled plasma.

  17. Feasibility report: Operation of light air cushion vehicle at McMurdo Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Dibbern, J. S.

    1987-02-01

    This report explores the viability of the use of an air cushion vehicle (ACV) or hovercraft to perform logistic and scientific support in the area of McMurdo Station, Antarctica. After a review of personnel assets and facilities at McMurdo Station to support the ACV plus a reconnaissance of the five major routes selected, it appears that an air cushion vehicle in the 1 to 1 1/2 ton payload class would be of significant value to support operations. It would reduce transit times for surface vehicle traverses on the routes selected and reduce requirements for expenditure of helicopter flight time in others. Of major significance is the ability to handle passenger/shuttle requirements between the Scott Base transition and Williams Field Skiway. Use of the ACV for high frequency passenger operations would help preserve the snow road for cargo operations during periods of road deterioration.

  18. Environmental Assessment: Construct Airfield Lighting Vault and Demolish Building 531 at Grand Forks Air Force Base

    DTIC Science & Technology

    2007-08-01

    frequent thunderstorms. Winters are long and severe with almost continuous snow cover. The spring and fall seasons are generally short transition periods...from the northwest during the late fall, winter, and spring , and from the southeast during the summer. Grand Forks County is included in the ND Air...Manvel, ND, approximately 10 miles northeast of Grand Forks AFB, the mean discharge of the Turtle River is 50.3 feet cubed per second (ft3/s). Peak

  19. Environmental Assessment for A-29 Light Air Support (LAS) Training Beddown

    DTIC Science & Technology

    2014-08-21

    solar systems , geothermal power plants, and wind generators. The Air Force continues to promote and install new renewable energy projects. The...Program NO2 Nitrogen Dioxide NOA Notice of Availability NOx Nitrogen Oxides NPDES National Pollutant Discharge Elimination System O3 Ozone...hostile forces at low altitudes. The A-29 incorporates fourth-generation avionics and weapons systems , and is capable of delivering precision guided

  20. Time-lapse 3-D measurements of a glucose biosensor in multicellular spheroids by light sheet fluorescence microscopy in commercial 96-well plates

    PubMed Central

    Maioli, Vincent; Chennell, George; Sparks, Hugh; Lana, Tobia; Kumar, Sunil; Carling, David; Sardini, Alessandro; Dunsby, Chris

    2016-01-01

    Light sheet fluorescence microscopy has previously been demonstrated on a commercially available inverted fluorescence microscope frame using the method of oblique plane microscopy (OPM). In this paper, OPM is adapted to allow time-lapse 3-D imaging of 3-D biological cultures in commercially available glass-bottomed 96-well plates using a stage-scanning OPM approach (ssOPM). Time-lapse 3-D imaging of multicellular spheroids expressing a glucose Förster resonance energy transfer (FRET) biosensor is demonstrated in 16 fields of view with image acquisition at 10 minute intervals. As a proof-of-principle, the ssOPM system is also used to acquire a dose response curve with the concentration of glucose in the culture medium being varied across 42 wells of a 96-well plate with the whole acquisition taking 9 min. The 3-D image data enable the FRET ratio to be measured as a function of distance from the surface of the spheroid. Overall, the results demonstrate the capability of the OPM system to measure spatio-temporal changes in FRET ratio in 3-D in multicellular spheroids over time in a multi-well plate format. PMID:27886235

  1. Time-lapse 3-D measurements of a glucose biosensor in multicellular spheroids by light sheet fluorescence microscopy in commercial 96-well plates

    NASA Astrophysics Data System (ADS)

    Maioli, Vincent; Chennell, George; Sparks, Hugh; Lana, Tobia; Kumar, Sunil; Carling, David; Sardini, Alessandro; Dunsby, Chris

    2016-11-01

    Light sheet fluorescence microscopy has previously been demonstrated on a commercially available inverted fluorescence microscope frame using the method of oblique plane microscopy (OPM). In this paper, OPM is adapted to allow time-lapse 3-D imaging of 3-D biological cultures in commercially available glass-bottomed 96-well plates using a stage-scanning OPM approach (ssOPM). Time-lapse 3-D imaging of multicellular spheroids expressing a glucose Förster resonance energy transfer (FRET) biosensor is demonstrated in 16 fields of view with image acquisition at 10 minute intervals. As a proof-of-principle, the ssOPM system is also used to acquire a dose response curve with the concentration of glucose in the culture medium being varied across 42 wells of a 96-well plate with the whole acquisition taking 9 min. The 3-D image data enable the FRET ratio to be measured as a function of distance from the surface of the spheroid. Overall, the results demonstrate the capability of the OPM system to measure spatio-temporal changes in FRET ratio in 3-D in multicellular spheroids over time in a multi-well plate format.

  2. Compact plane illumination plugin device to enable light sheet fluorescence imaging of multi-cellular organisms on an inverted wide-field microscope

    PubMed Central

    Guan, Zeyi; Lee, Juhyun; Jiang, Hao; Dong, Siyan; Jen, Nelson; Hsiai, Tzung; Ho, Chih-Ming; Fei, Peng

    2015-01-01

    We developed a compact plane illumination plugin (PIP) device which enabled plane illumination and light sheet fluorescence imaging on a conventional inverted microscope. The PIP device allowed the integration of microscope with tunable laser sheet profile, fast image acquisition, and 3-D scanning. The device is both compact, measuring approximately 15 by 5 by 5 cm, and cost-effective, since we employed consumer electronics and an inexpensive device molding method. We demonstrated that PIP provided significant contrast and resolution enhancement to conventional microscopy through imaging different multi-cellular fluorescent structures, including 3-D branched cells in vitro and live zebrafish embryos. Imaging with the integration of PIP greatly reduced out-of-focus contamination and generated sharper contrast in acquired 2-D plane images when compared with the stand-alone inverted microscope. As a result, the dynamic fluid domain of the beating zebrafish heart was clearly segmented and the functional monitoring of the heart was achieved. Furthermore, the enhanced axial resolution established by thin plane illumination of PIP enabled the 3-D reconstruction of the branched cellular structures, which leads to the improvement on the functionality of the wide field microscopy. PMID:26819828

  3. Effect of Percent Relative Humidity, Moisture Content, and Compression Force on Light-Induced Fluorescence (LIF) Response as a Process Analytical Tool.

    PubMed

    Shah, Ishan G; Stagner, William C

    2016-08-01

    The effect of percent relative humidity (16-84% RH), moisture content (4.2-6.5% w/w MC), and compression force (4.9-44.1 kN CF) on the light-induced fluorescence (LIF) response of 10% w/w active pharmaceutical ingredient (API) compacts is reported. The fluorescent response was evaluated using two separate central composite designs of experiments. The effect of % RH and CF on the LIF signal was highly significant with an adjusted R (2)  = 0.9436 and p < 0.0001. Percent relative humidity (p = 0.0022), CF (p < 0.0001), and % RH(2) (p = 0.0237) were statistically significant factors affecting the LIF response. The effects of MC and CF on LIF response were also statistically significant with a p value <0.0001 and adjusted R (2) value of 0.9874. The LIF response was highly impacted by MC (p < 0.0001), CF (p < 0.0001), and MC(2) (p = 0022). At 10% w/w API, increased % RH, MC, and CF led to a nonlinear decrease in LIF response. The derived quadratic model equations explained more than 94% of the data. Awareness of these effects on LIF response is critical when implementing LIF as a process analytical tool.

  4. Time-lapse 3-D measurements of a glucose biosensor in multicellular spheroids by light sheet fluorescence microscopy in commercial 96-well plates.

    PubMed

    Maioli, Vincent; Chennell, George; Sparks, Hugh; Lana, Tobia; Kumar, Sunil; Carling, David; Sardini, Alessandro; Dunsby, Chris

    2016-11-25

    Light sheet fluorescence microscopy has previously been demonstrated on a commercially available inverted fluorescence microscope frame using the method of oblique plane microscopy (OPM). In this paper, OPM is adapted to allow time-lapse 3-D imaging of 3-D biological cultures in commercially available glass-bottomed 96-well plates using a stage-scanning OPM approach (ssOPM). Time-lapse 3-D imaging of multicellular spheroids expressing a glucose Förster resonance energy transfer (FRET) biosensor is demonstrated in 16 fields of view with image acquisition at 10 minute intervals. As a proof-of-principle, the ssOPM system is also used to acquire a dose response curve with the concentration of glucose in the culture medium being varied across 42 wells of a 96-well plate with the whole acquisition taking 9 min. The 3-D image data enable the FRET ratio to be measured as a function of distance from the surface of the spheroid. Overall, the results demonstrate the capability of the OPM system to measure spatio-temporal changes in FRET ratio in 3-D in multicellular spheroids over time in a multi-well plate format.

  5. Understanding the light-emitting mechanism of an X-shape organic thermally activated delayed fluorescence molecule: First-principles study

    NASA Astrophysics Data System (ADS)

    Fan, Jianzhong; Cai, Lei; Lin, Lili; Wang, Chuankui

    2016-11-01

    The light-emitting mechanism of an X-shape organic thermally activated delayed fluorescent molecule is investigated based on first-principles calculations. It is found that there are two stable configurations for the ACRSA molecule, and that the molecule with conformer A is nonluminous. Further, the excited states dynamics of conformer B is studied. The normal modes analysis of the reorganization energy indicates that the non-radiation process of the first singlet excited state (S1) mainly comes from the out-of-plane vibration with low frequencies. Besides, calculations of energy levels of excited states demonstrate that the up-conversion happens between the S1 and T1 states.

  6. Effect of reverse intersystem crossing rate to suppress efficiency roll-off in organic light-emitting diodes with thermally activated delayed fluorescence emitters

    NASA Astrophysics Data System (ADS)

    Inoue, Munetomo; SereviĿius, Tomas; Nakanotani, Hajime; Yoshida, Kou; Matsushima, Toshinori; JuršĿnas, Saulius; Adachi, Chihaya

    2016-01-01

    Electroluminescence efficiency roll-off in organic light-emitting diodes with thermally activated delayed fluorescence emitters 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene (2CzPN) and 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN) is investigated by considering intramolecular exciton relaxation processes. Electroluminescence efficiency roll-off at high current density is dramatically suppressed using ACRXTN as an emitter instead of 2CzPN because of suppressed bimolecular exciton annihilation processes such as singlet⿿triplet and triplet⿿triplet annihilation. The rate constant of reverse intersystem crossing from triplet to singlet excited states of ACRXTN is about 300 times higher than that of 2CzPN, decreasing triplet exciton density and suppressing exciton annihilation processes under optical and electrical excitation.

  7. Application of quantitative light-induced fluorescence to determine the depth of demineralization of dental fluorosis in enamel microabrasion: a case report.

    PubMed

    Park, Tae-Young; Choi, Han-Sol; Ku, Hee-Won; Kim, Hyun-Su; Lee, Yoo-Jin; Min, Jeong-Bum

    2016-08-01

    Enamel microabrasion has become accepted as a conservative, nonrestorative method of removing intrinsic and superficial dysmineralization defects from dental fluorosis, restoring esthetics with minimal loss of enamel. However, it can be difficult to determine if restoration is necessary in dental fluorosis, because the lesion depth is often not easily recognized. This case report presents a method for analysis of enamel hypoplasia that uses quantitative light-induced fluorescence (QLF) followed by a combination of enamel microabrasion with carbamide peroxide home bleaching. We describe the utility of QLF when selecting a conservative treatment plan and confirming treatment efficacy. In this case, the treatment plan was based on QLF analysis, and the selected combination treatment of microabrasion and bleaching had good results.

  8. Application of quantitative light-induced fluorescence to determine the depth of demineralization of dental fluorosis in enamel microabrasion: a case report

    PubMed Central

    Park, Tae-Young; Choi, Han-Sol; Ku, Hee-Won; Kim, Hyun-Su; Lee, Yoo-Jin

    2016-01-01

    Enamel microabrasion has become accepted as a conservative, nonrestorative method of removing intrinsic and superficial dysmineralization defects from dental fluorosis, restoring esthetics with minimal loss of enamel. However, it can be difficult to determine if restoration is necessary in dental fluorosis, because the lesion depth is often not easily recognized. This case report presents a method for analysis of enamel hypoplasia that uses quantitative light-induced fluorescence (QLF) followed by a combination of enamel microabrasion with carbamide peroxide home bleaching. We describe the utility of QLF when selecting a conservative treatment plan and confirming treatment efficacy. In this case, the treatment plan was based on QLF analysis, and the selected combination treatment of microabrasion and bleaching had good results. PMID:27508165

  9. Development of an x-ray fluorescence microprobe at the National Synchrotron Light Source, Brookhaven National Laboratory: Early results: Comparison with data from other techniques

    SciTech Connect

    Smith, J.V.; Rivers, M.L.; Sutton, S.R.; Jones, K.W.; Hanson, A.L.; Gordon, B.M.

    1986-01-01

    Theoretical predictions for the detection levels in x-ray fluorescence analysis with a synchrotron storage ring are being achieved experimentally at several laboratories. This paper is deliberately restricted to the state of development of the Brookhaven National Laboratory/University of Chicago instruments. Analyses at the parts per million (ppM) level are being made using white light apertured to 20 ..mu..m and an energy dispersive system. This system is particularly useful for elements with Z > 20 in materials dominated by elements with Z < 20. Diffraction causes an interference for crystalline materials. Development of a focusing microprobe for tunable monochromatic x-rays and a wavelength dispersive spectrometer (WDS) is delayed by problems in shaping an 8:1 focusing mirror to the required accuracy. Reconnaissance analyses with a wiggler source on the CHESS synchrotron have been made in the K spectrum up to Z = 80.

  10. Sub-nanosecond time resolved light emission study for diffuse discharges in air under steep high voltage pulses

    NASA Astrophysics Data System (ADS)

    Tardiveau, P.; Magne, L.; Marode, E.; Ouaras, K.; Jeanney, P.; Bournonville, B.

    2016-10-01

    Pin-to-plane discharges in centimetre air gaps and standard conditions of pressure and temperature are generated under very high positive nanosecond scale voltage pulses. The experimental study is based on recordings of sub-nanosecond time resolved and Abel-processed light emission profiles and their complete correlation to electrical current waveforms. The effects of the voltage pulse features (amplitude between 20 and 90 kV, rise time between 2 and 5.2 ns, and time rate between 4 and 40 kV · ns-1) and the electrode configuration (gap distance between 10 and 30 mm, pin radius between 10 and 200 µm, copper, molybdenum or tungsten pin material) are described. A three time period development can be found: a glow-like structure with monotonic light profiles during the first 1.5 ns whose size depends on time voltage rate, a shell-like structure with bimodal profiles whose duration and extension in space depends on rise time, and either diffuse or multi-channel regime for the connection to the cathode plane according to gap distance. The transition of the light from monotonic to bimodal patterns reveals the relative effects and dynamics of streamer space charge and external laplacian field. A classical 2D-fluid model for streamer propagation has been used and adapted for very high and steep voltage pulses. It shows the formation of a strong space charge (streamer) very close to the pin, but also a continuity of emission between the pin and the streamer, and electric fields higher than the critical ionization field (28 kV · cm-1 in air) almost in the whole gap and very early in the discharge propagation.

  11. Fluorescent Optical Liquid-Level Sensor

    SciTech Connect

    Weiss, Jonathan D.

    1999-07-26

    An optical method of detecting liquid level is presented that uses fluorescence radiation generated in an impurity-doped glass or plastic slab. In operation, the slab is inserted into the liquid and pump light is coupled into it so that the light is guided by the slab-air interface above the liquid and escapes into the liquid just below its surface. Since the fluorescence is generated only in that section of the slab above the liquid, the fluorescence power will monotonically decrease with increasing liquid level. Thus, a relationship can be established between any signal proportional to it and the liquid level. Because optical fibers link the pump source and the detector of fluorescence radiation to the sensor, no electrical connections are needed in or near the liquid. Their absence vastly decreases the hazard associated with placing a liquid-level sensor in a potentially explosive environment. A laboratory prototype, consisting of a methyl styrene slab doped with an organic dye, has been built and successfully tested in water. Its response to liquid level when pumped by a tunable argon-ion laser at 476, 488, and 496 nm, and by a blue LED, is presented and shown to be consistent with theory. The fluorescence spectra are also presented and discussed.

  12. The Effects of Projected Future Demand Including Very Light Jet Air-Taxi Operations on U.S. National Airspace System Delays as a Function of Next Generation Air Transportation System Airspace Capacity

    NASA Technical Reports Server (NTRS)

    Smith, Jerry; Viken, Jeff; Dollyhigh, Samuel; Trani, Antonio; Baik, Hojong; Hinze, Nicholas; Ashiabor, Senanu

    2007-01-01

    This paper presents the results from a study which investigates the potential effects of the growth in air traffic demand including projected Very Light Jet (VLJ) air-taxi operations adding to delays experienced by commercial passenger air transportation in the year 2025. The geographic region studied is the contiguous United States (U.S.) of America, although international air traffic to and from the U.S. is included. The main focus of this paper is to determine how much air traffic growth, including VLJ air-taxi operations will add to enroute airspace congestion and determine what additional airspace capacity will be needed to accommodate the expected demand. Terminal airspace is not modeled and increased airport capacity is assumed.

  13. A Convenient Lecture Demonstration of Fluorescence.

    ERIC Educational Resources Information Center

    Burrows, Hugh D.; Axtell, Darrell D.

    1983-01-01

    Describes fluorescence experiments demonstrating that emitted light is at longer wavelengths than absorbed light and that fluorescence decays rapidly when the source of excitation is removed. Systems whose acidic and basic forms have different fluorescent characteristics are used to demonstrate fluorescence visible and invisible to the naked eye.…

  14. High-Throughput Growth Prediction for Lactuca sativa L. Seedlings Using Chlorophyll Fluorescence in a Plant Factory with Artificial Lighting

    PubMed Central