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Sample records for reactive highly fluorescent

  1. Biological detection and tagging using tailorable, reactive, highly fluorescent chemosensors.

    SciTech Connect

    Shepodd, Timothy J.; Zifer, Thomas; McElhanon, James Ross; Rahn, Larry A.

    2006-11-01

    This program was focused on the development of a fluorogenic chemosensor family that could tuned for reaction with electrophilic (e.g. chemical species, toxins) and nucleophilic (e.g. proteins and other biological molecules) species. Our chemosensor approach utilized the fluorescent properties of well-known berberine-type alkaloids. In situ chemosensor reaction with a target species transformed two out-of-plane, weakly conjugated, short-wavelength chromophores into one rigid, planar, conjugated, chromophore with strong long wavelength fluorescence (530-560 nm,) and large Stokes shift (100-180 nm). The chemosensor was activated with an isourea group which allowed for reaction with carboxylic acid moieties found in amino acids.

  2. Highly sensitive C-reactive protein (CRP) assay using metal-enhanced fluorescence (MEF)

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Keegan, Gemma L.; Stranik, Ondrej; Brennan-Fournet, Margaret E.; McDonagh, Colette

    2015-07-01

    Fluorescence has been extensively employed in the area of diagnostic immunoassays. A significant enhancement of fluorescence can be achieved when noble metal nanoparticles are placed in close proximity to fluorophores. This effect, referred to as metal-enhanced fluorescence (MEF), has the potential to produce immunoassays with a high sensitivity and a low limit of detection (LOD). In this study, we investigate the fluorescence enhancement effect of two different nanoparticle systems, large spherical silver nanoparticles (AgNPs) and gold edge-coated triangular silver nanoplates, and both systems were evaluated for MEF. The extinction properties and electric field enhancement of both systems were modeled, and the optimum system, spherical AgNPs, was used in a sandwich immunoassay for human C-reactive protein with a red fluorescent dye label. A significant enhancement in the fluorescence was observed, which corresponded to an LOD improvement of 19-fold compared to a control assay without AgNPs.

  3. Molecular switching fluorescence based high sensitive detection of label-free C-reactive protein on biochip.

    PubMed

    Islam, Md Shahinul; Yu, Hyunung; Lee, Hee Gu; Kang, Seong Ho

    2010-11-15

    A novel detection technique on biochip for the quantification of label-free C-reactive protein (CRP) based on molecular switching of fluorescence (MSF) is demonstrated by total internal reflection fluorescence microscopy. It alters fluorescence intensity of fluoreseinamine isomer 1 (FAI) upon binding with its specific ligand, O-phosphorylethanolamine (PEA). In the MSF-based detection, FAI was used as an ink, printed on a 3-glycidoxypropyl-trimethoxysilane (GPTS)-coated glass coverslip. With the addition of GPTS conjugated PEA solution to the FAI-printed coverslip, the fluorescence intensity was remarkably decreased. Addition of CRP increased fluorescence intensity linearly in the range of 800 aM to 500 fM (R=0.997). The MSF-based biochip assay for the estimation of CRP in human sera showed ∼200 times increased detection sensitivity in less than a third of the time to obtain results using a conventional enzyme-linked immunosorbent assay. This biochip detection is a promising new technique for the quantification of CRP molecules from trace amounts of clinical samples.

  4. Reactive Fluorescent Dyes For Urethane Coatings

    NASA Technical Reports Server (NTRS)

    Willis, Paul B.; Cuddihy, Edward F.

    1991-01-01

    Molecules of fluorescent dyes chemically bound in urethane conformal-coating materials to enable nondestructive detection of flaws in coats through inspection under ultraviolet light, according to proposal. Dye-bonding technique prevents outgassing of dyes, making coating materials suitable for use where flaw-free coats must be assured in instrumentation or other applications in which contamination by outgassing must be minimized.

  5. Chemical reactivation of quenched fluorescent protein molecules enables resin-embedded fluorescence microimaging

    NASA Astrophysics Data System (ADS)

    Xiong, Hanqing; Zhou, Zhenqiao; Zhu, Mingqiang; Lv, Xiaohua; Li, Anan; Li, Shiwei; Li, Longhui; Yang, Tao; Wang, Siming; Yang, Zhongqin; Xu, Tonghui; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

    2014-06-01

    Resin embedding is a well-established technique to prepare biological specimens for microscopic imaging. However, it is not compatible with modern green-fluorescent protein (GFP) fluorescent-labelling technique because it significantly quenches the fluorescence of GFP and its variants. Previous empirical optimization efforts are good for thin tissue but not successful on macroscopic tissue blocks as the quenching mechanism remains uncertain. Here we show most of the quenched GFP molecules are structurally preserved and not denatured after routine embedding in resin, and can be chemically reactivated to a fluorescent state by alkaline buffer during imaging. We observe up to 98% preservation in yellow-fluorescent protein case, and improve the fluorescence intensity 11.8-fold compared with unprocessed samples. We demonstrate fluorescence microimaging of resin-embedded EGFP/EYFP-labelled tissue block without noticeable loss of labelled structures. This work provides a turning point for the imaging of fluorescent protein-labelled specimens after resin embedding.

  6. Chemical reactivation of quenched fluorescent protein molecules enables resin-embedded fluorescence microimaging

    PubMed Central

    Xiong, Hanqing; Zhou, Zhenqiao; Zhu, Mingqiang; Lv, Xiaohua; Li, Anan; Li, Shiwei; Li, Longhui; Yang, Tao; Wang, Siming; Yang, Zhongqin; Xu, Tonghui; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

    2014-01-01

    Resin embedding is a well-established technique to prepare biological specimens for microscopic imaging. However, it is not compatible with modern green-fluorescent protein (GFP) fluorescent-labelling technique because it significantly quenches the fluorescence of GFP and its variants. Previous empirical optimization efforts are good for thin tissue but not successful on macroscopic tissue blocks as the quenching mechanism remains uncertain. Here we show most of the quenched GFP molecules are structurally preserved and not denatured after routine embedding in resin, and can be chemically reactivated to a fluorescent state by alkaline buffer during imaging. We observe up to 98% preservation in yellow-fluorescent protein case, and improve the fluorescence intensity 11.8-fold compared with unprocessed samples. We demonstrate fluorescence microimaging of resin-embedded EGFP/EYFP-labelled tissue block without noticeable loss of labelled structures. This work provides a turning point for the imaging of fluorescent protein-labelled specimens after resin embedding. PMID:24886825

  7. Exclusive examples of high-performance thin-film optical filters for fluorescence spectroscopy made by plasma-assisted reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lappschies, M.; Schallenberg, U.; Jakobs, S.

    2011-09-01

    For more than four decades band-pass filters are important components of microscopes used for the fluorescence spectroscopy. During all the time this special field of application has been one of the main drivers for research and development in thin-film optics, particularly for the thin-film design software and the coating technology. With a shortwave pass filter, a multi-notch filter, and a classical band-pass filter as examples of such filters provided for the latest generation of fluorescence microscopes we present the state-of-the-art in coating design and technology. Manufacturing these filters is a great challenge because the required spectral characteristics need necessarily multilayers with up to 300 layers and overall thicknesses up to 30 μm. In addition, the designs require also 3 to 5 nm as thinnest layers and all the layers are completely of non-quarterwave type. The filters were manufactured in a rapid-prototyping regime by a Leybold Helios plant using plasma-assisted reactive magnetron sputtering of thin films of different metal oxides. Designed and real spectra are compared and differences are discussed. Measurement results of other optical and non-optical characteristics as film stress, total integrated scattering, and micro roughness are presented.

  8. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

    2012-05-01

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  9. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M.; Waldo, Geoffrey S.; Kiss, Csaba

    2011-03-22

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  10. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

    2011-11-29

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  11. Detection of reactive oxygen species in mainstream cigarette smoke by a fluorescent probe

    NASA Astrophysics Data System (ADS)

    Liu, Li; Xu, Shi-jie; Li, Song-zhan

    2009-07-01

    A mass of reactive oxygen species(ROS) are produced in the process of smoking. Superfluous ROS can induce the oxidative stress in organism, which will cause irreversible damage to cells. Fluorescent probe is taken as a marker of oxidative stress in biology and has been applied to ROS detection in the field of biology and chemistry for high sensitivity, high simplicity of data collection and high resolution. As one type of fluorescent probe, dihydrorhodamine 6G (dR6G) will be oxidized to the fluorescent rhodamine 6G, which could be used to detect ROS in mainstream cigarette smoke. We investigated the action mechanism of ROS on dR6G, built up the standard curve of R6G fluorescence intensity with its content, achieved the variation pattern of R6G fluorescence intensity with ROS content in mainstream cigarette smoke and detected the contents of ROS from the 4 types of cigarettes purchased in market. The result shows that the amount of ROS has close relationship with the types of tobacco and cigarette production technology. Compared with other detecting methods such as electronic spin resonance(ESR), chromatography and mass spectrometry, this detection method by the fluorescent probe has higher efficiency and sensitivity and will have wide applications in the ROS detection field.

  12. Fluorescent detection of C-reactive protein using polyamide beads

    NASA Astrophysics Data System (ADS)

    Jagadeesh, Shreesha; Chen, Lu; Aitchison, Stewart

    2016-03-01

    Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient's location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

  13. Embedding and Chemical Reactivation of Green Fluorescent Protein in the Whole Mouse Brain for Optical Micro-Imaging

    PubMed Central

    Gang, Yadong; Zhou, Hongfu; Jia, Yao; Liu, Ling; Liu, Xiuli; Rao, Gong; Li, Longhui; Wang, Xiaojun; Lv, Xiaohua; Xiong, Hanqing; Yang, Zhongqin; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

    2017-01-01

    Resin embedding has been widely applied to fixing biological tissues for sectioning and imaging, but has long been regarded as incompatible with green fluorescent protein (GFP) labeled sample because it reduces fluorescence. Recently, it has been reported that resin-embedded GFP-labeled brain tissue can be imaged with high resolution. In this protocol, we describe an optimized protocol for resin embedding and chemical reactivation of fluorescent protein labeled mouse brain, we have used mice as experiment model, but the protocol should be applied to other species. This method involves whole brain embedding and chemical reactivation of the fluorescent signal in resin-embedded tissue. The whole brain embedding process takes a total of 7 days. The duration of chemical reactivation is ~2 min for penetrating 4 μm below the surface in the resin-embedded brain. This protocol provides an efficient way to prepare fluorescent protein labeled sample for high-resolution optical imaging. This kind of sample was demonstrated to be imaged by various optical micro-imaging methods. Fine structures labeled with GFP across a whole brain can be detected. PMID:28352214

  14. Embedding and Chemical Reactivation of Green Fluorescent Protein in the Whole Mouse Brain for Optical Micro-Imaging.

    PubMed

    Gang, Yadong; Zhou, Hongfu; Jia, Yao; Liu, Ling; Liu, Xiuli; Rao, Gong; Li, Longhui; Wang, Xiaojun; Lv, Xiaohua; Xiong, Hanqing; Yang, Zhongqin; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

    2017-01-01

    Resin embedding has been widely applied to fixing biological tissues for sectioning and imaging, but has long been regarded as incompatible with green fluorescent protein (GFP) labeled sample because it reduces fluorescence. Recently, it has been reported that resin-embedded GFP-labeled brain tissue can be imaged with high resolution. In this protocol, we describe an optimized protocol for resin embedding and chemical reactivation of fluorescent protein labeled mouse brain, we have used mice as experiment model, but the protocol should be applied to other species. This method involves whole brain embedding and chemical reactivation of the fluorescent signal in resin-embedded tissue. The whole brain embedding process takes a total of 7 days. The duration of chemical reactivation is ~2 min for penetrating 4 μm below the surface in the resin-embedded brain. This protocol provides an efficient way to prepare fluorescent protein labeled sample for high-resolution optical imaging. This kind of sample was demonstrated to be imaged by various optical micro-imaging methods. Fine structures labeled with GFP across a whole brain can be detected.

  15. Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations

    PubMed Central

    Kalyanaraman, Balaraman; Darley-Usmar, Victor; Davies, Kelvin J.A.; Dennery, Phyllis A.; Forman, Henry Jay; Grisham, Matthew B.; Mann, Giovanni E.; Moore, Kevin; Roberts, L. Jackson; Ischiropoulos, Harry

    2013-01-01

    The purpose of this position paper is to present a critical analysis of the challenges and limitations of the most widely used fluorescent probes for detecting and measuring reactive oxygen and nitrogen species. Where feasible, we have made recommendations for the use of alternate probes and appropriate analytical techniques that measure the specific products formed from the reactions between fluorescent probes and reactive oxygen and nitrogen species. We have proposed guidelines that will help present and future researchers with regard to the optimal use of selected fluorescent probes and interpretation of results. PMID:22027063

  16. 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.

  17. High yield fabrication of fluorescent nanodiamonds

    PubMed Central

    Boudou, Jean-Paul; Curmi, Patrick; Jelezko, Fedor; Wrachtrup, Joerg; Aubert, Pascal; Sennour, Mohamed; Balasubramanian, Gopalakrischnan; Reuter, Rolf; Thorel, Alain; Gaffet, Eric

    2009-01-01

    A new fabrication method to produce homogeneously fluorescent nanodiamonds with high yields is described. The powder obtained by high energy ball milling of fluorescent high pressure, high temperature diamond microcrystals was converted in a pure concentrated aqueous colloidal dispersion of highly crystalline ultrasmall nanoparticles with a mean size less than or equal to 10 nm. The whole fabrication yield of colloidal quasi-spherical nanodiamonds was several orders of magnitude higher than those previously reported starting from microdiamonds. The results open up avenues for the industrial cost-effective production of fluorescent nanodiamonds with well-controlled properties. PMID:19451687

  18. High yield fabrication of fluorescent nanodiamonds.

    PubMed

    Boudou, Jean-Paul; Curmi, Patrick A; Jelezko, Fedor; Wrachtrup, Joerg; Aubert, Pascal; Sennour, Mohamed; Balasubramanian, Gopalakrischnan; Reuter, Rolf; Thorel, Alain; Gaffet, Eric

    2009-06-10

    A new fabrication method to produce homogeneously fluorescent nanodiamonds with high yields is described. The powder obtained by high energy ball milling of fluorescent high pressure, high temperature diamond microcrystals was converted in a pure concentrated aqueous colloidal dispersion of highly crystalline ultrasmall nanoparticles with a mean size less than or equal to 10 nm. The whole fabrication yield of colloidal quasi-spherical nanodiamonds was several orders of magnitude higher than those previously reported starting from microdiamonds. The results open up avenues for the industrial cost-effective production of fluorescent nanodiamonds with well-controlled properties.

  19. Sensitivity of activatable reactive oxygen species probes by fluorescence spectroelectrochemistry

    PubMed Central

    Wang, Steven T.; Zhegalova, Natalia G.; Gustafson, Tiffany P.; Zhou, Andy; Sher, Joel; Achilefu, Samuel; Berezinand, Oleg Y.

    2013-01-01

    We have developed a new analytical method of evaluating activatable fluorescent probes for ROS detection using integrated fluorescence spectroelectrochemistry. Tafel formalism was applied to describe the process of the probes’ oxidation under electrochemical conditions and identify a novel parameter defined as the threshold oxidation potential. This potential can serve as an approximation to the equilibrium potential and can be utilized for determining the sensitivity of a probe to oxidation. Based upon the measured values of threshold potentials, the order of sensitivity towards oxidation among several mostly used probes was determined to be following (from highest to lowest): 2,7-dichlorodihydrofluorescein > dihydroethidium > dihydrorhodamine 123 > dihydrorhodamine 6G. The presented approach opens up a new direction in synthesizing and screening novel ROS probes with a well-defined sensitivity for in vitro and in vivo applications. PMID:23736882

  20. A fluorescence high-temperature sensor based on fluorescence lifetime

    NASA Astrophysics Data System (ADS)

    Wu, Jinling; Wang, Yutian; Wang, Xinian

    2006-11-01

    A kind of fluorescence optic-fiber temperature sensor is devised based on the alexandrite crystal. In this system, a new optic- fiber probe fabrication techniques is proposed. This system is particularly adapted to the temperature measurement in the range of room temperature to 650°C. During the cause of experimentation, using the PLD-PMTR (termed the Pulse Modulated Phase-locked detection with Two References) signal processing scheme. This temperature measurement method is proved to be effective and useful for its highly resolution and precision. It ensured the detected fluorescence signal to noise ratio was high enough to be measurable when the temperature is raised to 650°C.

  1. Time-resolved fluorescence immunoassay for C-reactive protein using colloidal semiconducting nanoparticles.

    PubMed

    Härmä, Harri; Toivonen, Juha; Soini, Juhani T; Hänninen, Pekka; Parak, Wolfgang J

    2011-01-01

    Besides the typical short-lived fluorescence with decay times in the nanosecond range, colloidal II/VI semiconductor nanoparticles dispersed in buffer also possess a long-lived fluorescence component with decay times in the microsecond range. Here, the signal intensity of the long-lived luminescence at microsecond range is shown to increase 1,000-fold for CdTe nanoparticles in PBS buffer. This long-lived fluorescence can be conveniently employed for time-gated fluorescence detection, which allows for improved signal-to-noise ratio and thus the use of low concentrations of nanoparticles. The detection principle is demonstrated with a time-resolved fluorescence immunoassay for the detection of C-reactive protein (CRP) using CdSe-ZnS nanoparticles and green light excitation.

  2. Diagnostic Implications of the Reactivity of Fluorescence Tracers

    SciTech Connect

    Sick, V; Westbrook, C

    2008-07-14

    Measurements of fuel concentration distributions with planar laser induced fluorescence of tracer molecules that are added to a base fuel are commonly used in combustion research and development. It usually is assumed that the tracer concentration follows the parent fuel concentration if physical properties such as those determining evaporation are matched. As an example to address this general issue a computational study of combustion of biacetyl/iso-octane mixtures was performed to investigate how well the concentration of biacetyl represents the concentration of iso-octane. For premixed mixture conditions with flame propagation the spatial concentration profiles of the two species in the flame front are separated by 110 {micro}m at 1 bar and by 11 {micro}m at 10 bar. For practical applications this spatial separation is insignificantly small. However, for conditions that mimic ignition and combustion in diesel and HCCI-like operation the differences in tracer and fuel concentration can be significant, exceeding hundreds of percent. At low initial temperature biacetyl was found to be more stable whereas at higher temperature (>1000K) iso-octane is more stable. Similar findings were obtained for a multi-component fuel comprised of iso-octane, n-heptane, methylcyclohexane, and toluene. It may be assumed that similar differences can exist for other tracer/fuel combinations. Caution has therefore to be applied when interpreting PLIF measurements in homogeneous reaction conditions such as in HCCI engine studies.

  3. Safe Disposal of Highly Reactive Chemicals.

    ERIC Educational Resources Information Center

    Lunn, George; Sansone, Eric B.

    1994-01-01

    Provides specific procedures for the disposal of a variety of highly reactive chemicals and reports the results of a study of their safe disposal. Disposal of some problematic sulfur-containing compounds are included. Procedures are based on a combination of literature review and author development. (LZ)

  4. Fluorescent Sulfur-Tagged Europium(III) Coordination Polymers for Monitoring Reactive Oxygen Species.

    PubMed

    Wang, Huai-Song; Bao, Wen-Jing; Ren, Shi-Bin; Chen, Ming; Wang, Kang; Xia, Xing-Hua

    2015-07-07

    Oxidative stress caused by reactive oxygen species (ROS) is harmful to biological systems and implicated in various diseases. A variety of selective fluorescent probes have been developed for detecting ROS to uncover their biological functions. Generally, the preparation of the fluorescent probes usually undergoes multiple synthetic steps, and the successful fluorescent sensing usually relies on trial-and-error tests. Herein we present a simple way to prepare fluorescent ROS probes that can be used both in biological and environmental systems. The fluorescent europium(III) coordination polymers (CPs) are prepared by simply mixing the precursors [2,2'-thiodiacetic acid and Eu(NO3)3·6H2O] in ethanol. Interestingly, with the increase of reaction temperature, the product undergoes a morphological transformation from microcrystal to nanoparticle while the structure and fluorescent properties retain. The fluorescence of the sulfur-tagged europium(III) CPs can be selectively quenched by ROS, and thus, sensitive and selective monitoring of ROS in aerosols by the microcrystals and in live cells by the nanoparticles has been achieved. The results reveal that the sulfur-tagged europium(III) CPs provide a novel sensor for imaging ROS in biological and environmental systems.

  5. High speed multispectral fluorescence lifetime imaging.

    PubMed

    Fereidouni, Farzad; Reitsma, Keimpe; Gerritsen, Hans C

    2013-05-20

    We report a spectrally resolved fluorescence lifetime imaging system based on time gated single photon detection with a fixed gate width of 200 ps and 7 spectral channels. Time gated systems can operate at high count rates but usually have large gate widths and sample only part of the fluorescence decay curve. In the system presented in this work, the fluorescence signal is sampled using a high speed transceiver. An error analysis is carried out to characterize the performance of both lifetime and spectral detection. The effect of gate width and spectral channel width on the accuracy of estimated lifetimes and spectral widths is described. The performance of the whole instrument is evaluated at count rates of up to 12 MHz. Accurate fluorescence lifetimes (error < 2%) are recorded at count rates as high as 5 MHz. This is limited by the PMT performance, not by the electronics. Analysis of the large spectral lifetime image sets is challenging and time-consuming. Here, we demonstrate the use of lifetime and spectral phasors for analyzing images of fibroblast cells with 2 different labeled components. The phasor approach provides a fast and intuitive way of analyzing the results of spectrally resolved fluorescence lifetime imaging experiments.

  6. Solvent-Free Synthesis and Fluorescence of a Thiol-Reactive Sensor for Undergraduate Organic Laboratories.

    PubMed

    Patterson, Anastasia L; May, Mary D; Visser, Bryan J; Kislukhin, Alexander A; Vosburg, David A

    2013-12-10

    A green organic laboratory experiment was developed in which students synthesize a sensor for thiols using a microscale, solventless Diels-Alder reaction at room temperature or 37 °C. The molecular probe is easily purified by column chromatography in a Pasteur pipet and characterized by thin-layer chromatography and NMR spectroscopy. The thiol-reactive sensor becomes intensely fluorescent upon exposure to thiols from N-acetylcysteine, bovine serum albumin, or human hair (pretreated with a reducing agent to reveal cysteine thiols in α-keratin). This fluorescence is observable even with micrograms of probe.

  7. Solvent-Free Synthesis and Fluorescence of a Thiol-Reactive Sensor for Undergraduate Organic Laboratories

    PubMed Central

    Patterson, Anastasia L.; May, Mary D.; Visser, Bryan J.; Kislukhin, Alexander A.; Vosburg, David A.

    2013-01-01

    A green organic laboratory experiment was developed in which students synthesize a sensor for thiols using a microscale, solventless Diels–Alder reaction at room temperature or 37 °C. The molecular probe is easily purified by column chromatography in a Pasteur pipet and characterized by thin-layer chromatography and NMR spectroscopy. The thiol-reactive sensor becomes intensely fluorescent upon exposure to thiols from N-acetylcysteine, bovine serum albumin, or human hair (pretreated with a reducing agent to reveal cysteine thiols in α-keratin). This fluorescence is observable even with micrograms of probe. PMID:24415795

  8. Measurement of OH reactivity by laser flash photolysis coupled with laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Stone, Daniel; Whalley, Lisa K.; Ingham, Trevor; Edwards, Peter M.; Cryer, Danny R.; Brumby, Charlotte A.; Seakins, Paul W.; Heard, Dwayne E.

    2016-07-01

    OH reactivity (k'OH) is the total pseudo-first-order loss rate coefficient describing the removal of OH radicals to all sinks in the atmosphere, and is the inverse of the chemical lifetime of OH. Measurements of ambient OH reactivity can be used to discover the extent to which measured OH sinks contribute to the total OH loss rate. Thus, OH reactivity measurements enable determination of the comprehensiveness of measurements used in models to predict air quality and ozone production, and, in conjunction with measurements of OH radical concentrations, to assess our understanding of OH production rates. In this work, we describe the design and characterisation of an instrument to measure OH reactivity using laser flash photolysis coupled to laser-induced fluorescence (LFP-LIF) spectroscopy. The LFP-LIF technique produces OH radicals in isolation, and thus minimises potential interferences in OH reactivity measurements owing to the reaction of HO2 with NO which can occur if HO2 is co-produced with OH in the instrument. Capabilities of the instrument for ambient OH reactivity measurements are illustrated by data collected during field campaigns in London, UK, and York, UK. The instrumental limit of detection for k'OH was determined to be 1.0 s-1 for the campaign in London and 0.4 s-1 for the campaign in York. The precision, determined by laboratory experiment, is typically < 1 s-1 for most ambient measurements of OH reactivity. Total uncertainty in ambient measurements of OH reactivity is ˜ 6 %. We also present the coupling and characterisation of the LFP-LIF instrument to an atmospheric chamber for measurements of OH reactivity during simulated experiments, and provide suggestions for future improvements to OH reactivity LFP-LIF instruments.

  9. Probing oxidative stress: Small molecule fluorescent sensors of metal ions, reactive oxygen species, and thiols

    PubMed Central

    Hyman, Lynne M.; Franz, Katherine J.

    2013-01-01

    Oxidative stress is a common feature shared by many diseases, including neurodegenerative diseases. Factors that contribute to cellular oxidative stress include elevated levels of reactive oxygen species, diminished availability of detoxifying thiols, and the misregulation of metal ions (both redox-active iron and copper as well as non-redox active calcium and zinc). Deciphering how each of these components interacts to contribute to oxidative stress presents an interesting challenge. Fluorescent sensors can be powerful tools for detecting specific analytes within a complicated cellular environment. Reviewed here are several classes of small molecule fluorescent sensors designed to detect several molecular participants of oxidative stress. We focus our review on describing the design, function and application of probes to detect metal cations, reactive oxygen species, and intracellular thiol-containing compounds. In addition, we highlight the intricacies and complications that are often faced in sensor design and implementation. PMID:23440254

  10. Ultraviolet irradiation-dependent fluorescence enhancement of hemoglobin catalyzed by reactive oxygen species.

    PubMed

    Pan, Leiting; Wang, Xiaoxu; Yang, Shuying; Wu, Xian; Lee, Imshik; Zhang, Xinzheng; Rupp, Romano A; Xu, Jingjun

    2012-01-01

    Ultraviolet (UV) light has a potent effect on biological organisms. Hemoglobin, an oxygen-transport protein, plays an irreplaceable role in sustaining life of all vertebrates. In this study we scrutinize the effects of ultraviolet irradiation (UVI) as well as visible irradiation on the fluorescence characteristics of bovine hemoglobin (BHb) in vitro. Data show that UVI results in fluorescence enhancement of BHb in a dose-dependent manner. Furthermore, UVI-induced fluorescence enhancement is significantly increased when BHb is pretreated with hydrogen peroxide (H(2)O(2)), a type of reactive oxygen species (ROS). Meanwhile, The water-soluble antioxidant vitamin C suppresses this UVI-induced fluorescence enhancement. In contrast, green light irradiation does not lead to fluorescence enhancement of BHb no matter whether H(2)O(2) is acting on the BHb solution or not. Taken together, these results indicate that catalysis of ROS and UVI-dependent irradiation play two key roles in the process of UVI-induced fluorescence enhancement of BHb.

  11. Fluorescent silica nanoparticles with chemically reactive surface: Controlling spatial distribution in one-step synthesis.

    PubMed

    Vera, María L; Cánneva, Antonela; Huck-Iriart, Cristián; Requejo, Felix G; Gonzalez, Mónica C; Dell'Arciprete, María L; Calvo, Alejandra

    2017-06-15

    The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface enables a wide range of applications, as amino groups could be easily linked with different biomolecules for targeting purposes. This kind of nanoparticle is regularly synthesized by methods that employ templates, additional nanoparticle formation or multiple pathway process. However, a one-step synthesis will be an efficient approach in this sort of bifunctional hybrid nanoparticles. A co-condensation sol-gel synthesis of hybrid fluorescent silica nanoparticle where developed. The chemical and morphological characterization of the particles where investigated by DRIFTS, XPS, SEM and SAXS. The nanoparticle fluorescent properties were also assessed by excitation-emission matrices and time resolved experiments. We have developed a one-pot synthesis method that enables the simultaneous incorporation of functionalities, the fluorescent molecule and the amino group, by controlling co-condensation process. An exhaustive characterization allows the definition of the spatial distribution of the fluorescent probe, fluorescein isothiocyanate, inside the particle and reactive amino groups on the surface of the nanoparticle with diameter about 100nm.

  12. Highly Fluorescent Noble Metal Quantum Dots

    PubMed Central

    Zheng, Jie; Nicovich, Philip R.; Dickson, Robert M.

    2009-01-01

    Highly fluorescent, water-soluble, few-atom noble metal quantum dots have been created that behave as multi-electron artificial atoms with discrete, size-tunable electronic transitions throughout the visible and near IR. These “molecular metals” exhibit highly polarizable transitions and scale in size according to the simple relation, Efermi/N1/3, predicted by the free electron model of metallic behavior. This simple scaling indicates that fluorescence arises from intraband transitions of free electrons and that these conduction electron transitions are the low number limit of the plasmon – the collective dipole oscillations occurring when a continuous density of states is reached. Providing the “missing link” between atomic and nanoparticle behavior in noble metals, these emissive, water-soluble Au nanoclusters open new opportunities for biological labels, energy transfer pairs, and light emitting sources in nanoscale optoelectronics. PMID:17105412

  13. Fluorescence-based assay for reactive oxygen species: A protective role for creatinine

    SciTech Connect

    Glazer, A.N. )

    1988-06-01

    Attack by reactive oxygen species leads to a decay in phycoerythrin fluorescence emission. This phenomenon provides a versatile new assay for small molecules and macromolecules that can function as protective compounds. With 1-2 {times} 10{sup {minus}8} M phycoerythrin, under conditions where peroxyl radical generation is rate-limiting, the fluorescence decay follows apparent zero-order kinetics. On reaction with HO{center dot}, generated with the ascorbate-Cu{sup 2+} system, the fluorescence decays with apparent first-order kinetics. Examination of the major components of human urine in this assay confirms that at physiological concentrations, urate protects against both types of oxygen radicals. A novel finding is that creatinine protects efficiently by a chelation mechanism against radical damage in the ascorbate-Cu{sup 2+} system at creatinine, ascorbate, and Cu{sup 2+} concentrations comparable to those in normal urine. Urate and creatinine provide complementary modes of protection against reactive oxygen species in the urinary tract.

  14. Recognition- and reactivity-based fluorescent probes for studying transition metal signaling in living systems.

    PubMed

    Aron, Allegra T; Ramos-Torres, Karla M; Cotruvo, Joseph A; Chang, Christopher J

    2015-08-18

    Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed "recognition" and "reactivity". Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give three recent

  15. Recognition- and Reactivity-Based Fluorescent Probes for Studying Transition Metal Signaling in Living Systems

    PubMed Central

    2015-01-01

    Conspectus Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed “recognition” and “reactivity”. Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give

  16. Fluorescence quenching at high quencher concentrations

    NASA Astrophysics Data System (ADS)

    Peak, David; Werner, T. C.; Dennin, Richard M., Jr.; Baird, James K.

    1983-10-01

    Chemical reactions occurring in dense media at high reactant concentrations can be described by rate ``constants'' which are actually functions of concentration. We present a theoretical model in which this so-called rate constant ``renormalization'' occurs for the specific case of fluorescence quenching in solution. We show that both the quenching and the excitation rate constants can become concentration dependent. We fit our theory to several sets of experimental data—our own and some from the literature—and show that excellent agreement is obtained by varying a single free parameter, namely, the efficiency with which a fluorophore-quencher collision leads to a quench of the excited state.

  17. Novel Nanophosphors for High Efficiency Fluorescent Lamps

    SciTech Connect

    Alok Srivatava

    2007-03-31

    This is the Final Report of the Novel Nanophosphors for High Efficiency Fluorescent Lamps, Department of Energy (DOE). The overall goal of this three-year program is to develop novel hybrid phosphors by coating commercially available lamp phosphors with highly stable wide band-gap nanocrystalline phosphors (NCP). The prime technical approach is the development of NCP quantum-splitting phosphor (QSP) and ultra-violet (UV) emitting phosphors with quantum efficiencies exceeding that of the conventional phosphors at 185 nm. The novel hybrid phosphors will increase the efficiency of the fluorescent lamps by up to 32%, enabling total energy savings of 0.26 quads, the reduction in the U.S. energy bill by $6.5 billion and the reduction of the annual carbon emission by 4.1 billion kilogram. Our work started by investigating through modeling calculations the requirement for the particle size of the NCP. Our work to develop suitable nanocrystalline phosphors started with the known oxide quantum splitting and UV emitting phosphors. We demonstrated several synthesis techniques for the production of high quality nanocrystalline materials that crystallizes in the desired phase and with the desired particle size. In collaboration with our subcontractor we demonstrated the feasibility for the manufacture of NC phosphors. We also demonstrated novel techniques of coating the NCP on the surface of micron sized phosphors. Our chief achievement pertains to the successful testing of the coated hybrid phosphor systems in linear fluorescent lamps. In linear fluorescent lamp tests, we have demonstrated up to 7% increase in the efficacy of hybrid phosphors over the conventional (uncoated) phosphors. We have also demonstrated the improvement in the lumen maintenance of the coated phosphors. A hybrid phosphor system based on the commercial red emitting phosphor, Y{sub 2}O{sub 3}:Eu{sup 3+} did not show the anticipated improvement in lamp efficacy. We explored the reasons for this observation

  18. In Vivo Imaging of Retinal Oxidative Stress Using a Reactive Oxygen Species–Activated Fluorescent Probe

    PubMed Central

    Prunty, Megan C.; Aung, Moe H.; Hanif, Adam M.; Allen, Rachael S.; Chrenek, Micah A.; Boatright, Jeffrey H.; Thule, Peter M.; Kundu, Kousik; Murthy, Niren; Pardue, Machelle T.

    2015-01-01

    Purpose In vivo methods for detecting oxidative stress in the eye would improve screening and monitoring of the leading causes of blindness: diabetic retinopathy, glaucoma, and age-related macular degeneration. Methods To develop an in vivo biomarker for oxidative stress in the eye, we tested the efficacy of a reactive oxygen species (ROS)–activated, near-infrared hydrocyanine-800CW (H-800CW) fluorescent probe in light-induced retinal degeneration (LIRD) mouse models. After intravitreal delivery in LIRD rats, fluorescent microscopy was used to confirm that the oxidized H-800CW appeared in the same retinal layers as an established ROS marker (dichlorofluorescein). Results Dose–response curves of increasing concentrations of intravenously injected H-800CW demonstrated linear increases in both intensity and total area of fundus hyperfluorescence in LIRD mice, as detected by scanning laser ophthalmoscopy. Fundus hyperfluorescence also correlated with the duration of light damage and functional deficits in vision after LIRD. In LIRD rats with intravitreal injections of H-800CW, fluorescent labeling was localized to photoreceptor inner segments, similar to dichlorofluorescein. Conclusions Hydrocyanine-800CW detects retinal ROS in vivo and shows potential as a novel biomarker for ROS levels in ophthalmic diseases. PMID:26348635

  19. Reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

    2012-10-01

    Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

  20. Immune reactivity after high-dose irradiation

    SciTech Connect

    Gassmann, W.; Wottge, H.U.; von Kolzynski, M.; Mueller-Ruchholtz, W.

    1986-03-01

    Immune reactivity after total-body irradiation was investigated in rats using skin graft rejection as the indicator system. After sublethal irradiation with 10.5 Gy (approximately 50% lethality/6 weeks) the rejection of major histocompatibility complex allogeneic skin grafts was delayed significantly compared with nonirradiated control animals (28 versus 6.5 days). In contrast, skin grafts were rejected after 7.5 days in sublethally irradiated animals and 7 days in lethally irradiated animals if additional skin donor type alloantigens--namely, irradiated bone marrow cells--were given i.v. either simultaneously or with a delay of not more than 24 hr after the above conditioning regimen. These reactions were alloantigen-specific. They were observed in six different strain combinations with varying donors and recipients. Starting on day 2 after irradiation, i.v. injection of bone marrow gradually lost its effectivity and skin grafts were no longer rejected with uniform rapidity; skin donor marrow given on days 4 or 8 did not accelerate skin graft rejection at all. These data show that for approximately 1-2 days after high-dose total-body irradiation rats are still capable of starting a vigorous immune reaction against i.v.-injected alloantigens. The phenomenon of impaired rejection of skin grafted immediately after high-dose irradiation appears to result from the poor accessibility of skin graft alloantigens during the early postirradiation phase when vascularization of the grafted skin is insufficient.

  1. On the Inclusion of Inorganic Chemical Reactivity in High School Chemistry: The Reactivity Network.

    ERIC Educational Resources Information Center

    Mellon, E. K.

    1989-01-01

    Reports the function of the Reactivity Network which is to translate reactivity data from the primary literature into some 30 reviews for high school teachers and curriculum developers and to disseminate that information nationwide. Discusses a needs assessment done for the project. (MVL)

  2. A cross-reactive sensor array for the fluorescence qualitative analysis of heavy metal ions.

    PubMed

    Kang, Huaizhi; Lin, Liping; Rong, Mingcong; Chen, Xi

    2014-11-01

    A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent indicators has been designed for the detection of seven heavy metal ions (Ag(+), Hg(2+), Pb(2+), Cu(2+), Cr(3+), Mn(2+) and Cd(2+)). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. Results showed that the sensor array could be used to qualitatively analyze the selected heavy metal ions. The array performance was also evaluated in the identification of known and unknown samples and the preliminary results suggested the promising practicability of the designed sensor assay.

  3. High-throughput imaging of adult fluorescent zebrafish with an LED fluorescence macroscope

    PubMed Central

    Blackburn, Jessica S; Liu, Sali; Raimondi, Aubrey R; Ignatius, Myron S; Salthouse, Christopher D; Langenau, David M

    2011-01-01

    Zebrafish are a useful vertebrate model for the study of development, behavior, disease and cancer. A major advantage of zebrafish is that large numbers of animals can be economically used for experimentation; however, high-throughput methods for imaging live adult zebrafish had not been developed. Here, we describe protocols for building a light-emitting diode (LED) fluorescence macroscope and for using it to simultaneously image up to 30 adult animals that transgenically express a fluorescent protein, are transplanted with fluorescently labeled tumor cells or are tagged with fluorescent elastomers. These protocols show that the LED fluorescence macroscope is capable of distinguishing five fluorescent proteins and can image unanesthetized swimming adult zebrafish in multiple fluorescent channels simultaneously. The macroscope can be built and used for imaging within 1 day, whereas creating fluorescently labeled adult zebrafish requires 1 hour to several months, depending on the method chosen. The LED fluorescence macroscope provides a low-cost, high-throughput method to rapidly screen adult fluorescent zebrafish and it will be useful for imaging transgenic animals, screening for tumor engraftment, and tagging individual fish for long-term analysis. PMID:21293462

  4. Cross-reactivity of stimulants found in sports drug testing by two fluorescence polarization immunoassays.

    PubMed

    de la Torre, R; Badia, R; Gonzàlez, G; García, M; Pretel, M J; Farré, M; Segura, J

    1996-01-01

    We investigated the usefulness of immunological methods for presumptive detection of stimulants found in sports drug testing. The ingestion of substances that show no cross-reactivity in tests commercially available for the detection of amphetamines can produce positive results in the urine. Human metabolism contributes to the positive results of some urine samples when the parent compound does not cross-react with the antibodies of the assay. Urine samples from healthy volunteers given stimulants were tested by chromatographic methods and by two different fluorescence polarization immunoassays (FPIA) from Abbott Laboratories for the analysis of amphetamines. According to the results obtained, we classified stimulants into four groups: detectable stimulants that gave rise to amphetamine by human metabolism (group 1); detectable ephedrines and related compounds, appearing in the urine either as parent compounds or originated by metabolism (group 2); detectable stimulants that displayed actual cross-reactivity with amphetamine tests (group 3); and stimulants not detected by FPIA (group 4). Most of the true doping cases due to the ingestion of stimulants may be detected by FPIA. The specificity of the results may be increased by combining immunological assays with different antibodies.

  5. Facile synthesis of fluorescent polymer nanoparticles by covalent modification-nanoprecipitation of amine-reactive ester polymers.

    PubMed

    Lee, Yeonju; Hanif, Sadaf; Theato, Patrick; Zentel, Rudolf; Lim, Jeewoo; Char, Kookheon

    2015-06-01

    Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers, which are then easily modified with a commercially available dye and subsequently subjected to nanoprecipitation. The resulting NPs, with low size polydispersity, show an enhanced emission quantum yield when compared with the same dye molecules in solution.

  6. Taming the highly reactive oxonium ion.

    PubMed

    Haley, Michael M

    2009-01-01

    'Onium rings: Incorporation of the trivalent oxygen atom as a structural element within the tricyclic core of 1-3 imparts unprecedented stability to this "extraordinary" class of tertiary oxonium ions. Cation 1 is the least reactive and can be refluxed in water for 72 hours with no noticeable decomposition.

  7. Using fluorescence-activated flow cytometry to determine reactive oxygen species formation and membrane lipid peroxidation in viable boar spermatozoa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fluorescence-activated flow cytometry analyses were developed for determination of reactive oxygen species (ROS) formation and membrane lipid peroxidation in live spermatozoa loaded with, respectively, hydroethidine (HE) or the lipophilic probe 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-d...

  8. Fluorescent-conjugated polymer superquenching facilitates highly sensitive detection of proteases

    NASA Astrophysics Data System (ADS)

    Kumaraswamy, Sriram; Bergstedt, Troy; Shi, Xiaobo; Rininsland, Frauke; Kushon, Stuart; Xia, Wensheng; Ley, Kevin; Achyuthan, Komandoor; McBranch, Duncan; Whitten, David

    2004-05-01

    Sensor formats have been developed for detecting the activity of proteolytic enzymes based on fluorescent conjugated polymer superquenching. These sensors employ a reactive peptide sequence within a tether linking a quencher to a biotin. The peptide binds to sensors containing colocated biotin-binding protein and fluorescent polymer by means of biotin-biotin binding protein interactions, resulting in a strong quenching of polymer fluorescence. Enzyme-mediated cleavage of the peptide results in a reversal of the fluorescence quenching. These assays for protease activity are simple, sensitive, fast, and have the specificity required for screening chemical libraries for novel protease inhibitors in a high-throughput screening assay environment. These assays have been demonstrated for enterokinase, caspase-3/7, and -secretase.

  9. Development of Highly Fluorescent Materials Based on Thiophenylimidazole Dyes

    NASA Technical Reports Server (NTRS)

    Santos, Javier; Bu, Xiu R.; Mintz, Eric A.; Meador, Michael A. (Technical Monitor)

    2000-01-01

    Organic fluorescent materials are expected to find many potential applications in optical devices and photo-functionalized materials. Although many investigations have been focused on heterocyclic compounds such as coumarins, bipyridines, rhodamines, and pyrrole derivatives, little is known for fluorescent imidazole materials. We discovered that one particular class of imidazole derivatives is highly fluorescent. A series of monomeric and polymeric based fluorescent dyes were prepared containing a thiophene unit at the second position of the imidazole ring. Dependence of fluorescence efficiency on parameters such as solvent polarity and substituent groups has been investigated. It was found that a formyl group at the 2-position of the thiophene ring dramatically enhance fluorescence properties. Ion recognition probes indicated their potential as sensor materials. These fluorophores have flexibility for introduction of versatile substituent groups that could improve the fluorescence efficiency and sensor properties.

  10. Proximity of reactive cysteine residue and flavin in Escherichia coli pyruvate oxidase as estimated by fluorescence energy transfer.

    PubMed

    Koland, J G; Gennis, R B

    1982-08-31

    Pyruvate oxidase of Escherichia coli possesses a reactive cysteine residue believed to be associated with the thiamin pyrophosphate (TPP) binding site. This residue is not reactive in the presence of TPP. Exposure of the enzyme to cysteine-directed fluorescent reagents results in the formation of fluorescent protein conjugates. Although these reagents do not react solely with the TPP-protectable cysteine residue, the fluorescence emission spectrum of a probe attached to this residue can be obtained by a difference technique. It was determined that the fluorescence emission of probes at the TPP-protectable site is very low due to energy transfer to the FAD coenzyme and that this fluorescence is greatly enhanced upon reduction or extraction of the flavin. Application of fluorescence energy transfer theory enabled the determination of an upper limit for the distance between the probes at the TPP-protectable site and the flavin adenine dinucleotide (FAD) (roughly 20 A). Thus, the TPP binding site and the FAD coenzyme are likely in close proximity.

  11. High-Collection-Efficiency Fluorescence Detection Cell

    NASA Technical Reports Server (NTRS)

    Hanisco, Thomas; Cazorla, Maria; Swanson, Andrew

    2013-01-01

    A new fluorescence cell has been developed for the laser induced fluorescence (LIF) detection of formaldehyde. The cell is used to sample a flow of air that contains trace concentrations of formaldehyde. The cell provides a hermetically sealed volume in which a flow of air containing formaldehyde can be illuminated by a laser. The cell includes the optics for transmitting the laser beam that is used to excite the formaldehyde and for collecting the resulting fluorescence. The novelty of the cell is its small size and simple design that provides a more robust and cheaper alternative to the state of the art. Despite its simplicity, the cell provides the same sensitivity to detection as larger, more complicated cells.

  12. Highly Selective Fluorescent Sensing of Proteins Based on a Fluorescent Molecularly Imprinted Nanosensor

    PubMed Central

    Deng, Qiliang; Wu, Jianhua; Zhai, Xiaorui; Fang, Guozhen; Wang, Shuo

    2013-01-01

    A fluorescent molecularly imprinted nanosensor was obtained by grafting imprinted polymer onto the surface of multi-wall carbon nanotubes and post-imprinting treatment with fluorescein isothiocyanate (FITC). The fluorescence of lysozyme-imprinted polymer (Lys-MIP) was quenched more strongly by Lys than that of nonimprinted polymer (NIP), which indicated that the Lys-MIP could recognize Lys. The resulted imprinted material has the ability to selectively sense a target protein, and an imprinting factor of 3.34 was achieved. The Lys-MIP also showed selective detection for Lys among other proteins such as cytochrome C (Cyt C), hemoglobin (HB) and bovine serum albumin (BSA) due to the imprinted sites in the Lys-MIP. This approach combines the high selectivity of surface molecular imprinting technology and fluorescence, and converts binding events into detectable signals by monitoring fluorescence spectra. Therefore, it will have further applications for Lys sensing. PMID:24077318

  13. Carbon dots with high fluorescence quantum yield: the fluorescence originates from organic fluorophores

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Yang, Jian Hai; Zeng, Hai Bo; Chen, Yong Mei; Yang, Sheng Chun; Wu, Chao; Zeng, Hao; Yoshihito, Osada; Zhang, Qiqing

    2016-07-01

    In this contribution, we have shown that the organic fluorophores, 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-3,7-dicarboxylic acid (TPDCA) and 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-7-carboxylic acid (TPCA), are the main ingredients and fluorescence origins of N,S-CDs via systematic analyses. It inspires us to deeply analyze and understand the fluorescence origins of carbon dots with high fluorescence quantum yields, which will expand their applications.In this contribution, we have shown that the organic fluorophores, 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-3,7-dicarboxylic acid (TPDCA) and 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-7-carboxylic acid (TPCA), are the main ingredients and fluorescence origins of N,S-CDs via systematic analyses. It inspires us to deeply analyze and understand the fluorescence origins of carbon dots with high fluorescence quantum yields, which will expand their applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00451b

  14. Reactive Plasticizers for High Temperature Quinoxaline Thermoplastics

    DTIC Science & Technology

    1976-06-01

    involves essentially two steps, consolidation of boardy prepreg into sheet stock and thermoforming the sheet stock into structural components. A...problem associated with the fabrication process is the high temperatures required in both the consolidation and thermoforming operations. High processing

  15. X-ray Excited Optical Fluorescence and Diffraction Imaging of Reactivity and Crystallinity in a Zeolite Crystal: Crystallography and Molecular Spectroscopy in One.

    PubMed

    Ristanović, Zoran; Hofmann, Jan P; Richard, Marie-Ingrid; Jiang, Tao; Chahine, Gilbert A; Schülli, Tobias U; Meirer, Florian; Weckhuysen, Bert M

    2016-06-20

    Structure-activity relationships in heterogeneous catalysis are challenging to be measured on a single-particle level. For the first time, one X-ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm-resolved X-ray diffraction (μ-XRD) and X-ray excited optical fluorescence (μ-XEOF) maps of the crystallinity and Brønsted reactivity of a zeolite crystal previously reacted with a styrene probe molecule. The local gradients in chemical reactivity (derived from μ-XEOF) were correlated with local crystallinity and framework Al content, determined by μ-XRD. Two distinctly different types of fluorescent species formed selectively, depending on the local zeolite crystallinity. The results illustrate the potential of this approach to resolve the crystallographic structure of a porous material and its reactivity in one experiment via X-ray induced fluorescence of organic molecules formed at the reactive centers.

  16. A nano-selenium reactive barrier approach for managing mercury over the life-cycle of compact fluorescent lamps.

    PubMed

    Lee, Brian; Sarin, Love; Johnson, Natalie C; Hurt, Robert H

    2009-08-01

    Compact fluorescent lamps contain small quantities of mercury, release of which can lead to human exposures of potential concern in special cases involving multiple lamps, confined spaces, or young children. The exposure scenarios typically involve solid lamp debris that slowly releases elemental mercury vapor to indoor spaces. Here we propose and demonstrate a reactive barrier approach for the suppression of that mercury release, and demonstrate the concept using uncoated amorphous nanoselenium as the reactive component. Multilayer structures containing an impregnated reactive layer and a mercury vapor barrier are fabricated, characterized, and evaluated in three exposure prevention scenarios: carpeted break sites, disposal/recycling bags, and boxes as used for retail sales, shipping, and collection. The reactive barriers achieve significant suppression of mercury release to indoor spaces in each of thethree scenarios. The nanoselenium barriers also exhibit a unique indicator function that can reveal the location of Hg contamination by local reaction-induced change in optical properties. The article also presents results on equilibrium Hg vapor pressure above lamp debris, mathematical modeling of reaction and transport processes within reactive barriers, and landfill stability of nanoselenium and its reaction products.

  17. A Nano-Selenium Reactive Barrier Approach for Managing Mercury over the Life-Cycle of Compact Fluorescent Lamps

    PubMed Central

    Lee, Brian; Sarin, Love; Johnson, Natalie C.; Hurt, Robert H.

    2013-01-01

    Compact fluorescent lamps contain small quantities of mercury, whose release can lead to human exposures of potential concern in special cases involving multiple lamps, confined spaces, or young children. The exposure scenarios typically involve solid lamp debris that slowly releases elemental mercury vapor to indoor spaces. Here we propose and demonstrate a reactive barrier approach for the suppression of that mercury release, and demonstrate the concept using uncoated amorphous nano-selenium as the reactive component. Multi-layer structures containing an impregnated reactive layer and a mercury vapor barrier are fabricated, characterized, and evaluated in three exposure prevention scenarios: carpeted break sites, disposal/recycling bags, and boxes as used for retail sales, shipping and collection. The reactive barriers achieve significant suppression of mercury release to indoor spaces in each of the three scenarios. The nano-selenium barriers also exhibit a unique indicator function that can reveal the location of Hg-contamination by local reaction-induced change in optical properties. The article also presents results on equilibrium Hg vapor pressure above lamp debris, mathematical modeling of reaction and transport processes within reactive barriers, and landfill stability of nano-selenium and its reaction products. PMID:19731697

  18. Reactive high power impulse magnetron sputtering: combining simulation and experiment

    NASA Astrophysics Data System (ADS)

    Kozak, Tomas; Vlcek, Jaroslav

    2016-09-01

    Reactive high-power impulse magnetron sputtering (HiPIMS) has recently been used for preparation of various oxide films with high application potential, such as TiO2, ZrO2, Ta2O5, HfO2, VO2. Using our patented method of pulsed reactive gas flow control with an optimized reactive gas inlet, we achieved significantly higher deposition rates compared to typical continuous dc magnetron depositions. We have developed a time-dependent model of the reactive HiPIMS. The model includes a depth-resolved description of the sputtered target (featuring sputtering, implantation and knock-on implantation processes) and a parametric description of the discharge plasma (dissociation of reactive gas, ionization and return of sputtered atoms and gas rarefaction). The model uses a combination of experimental and simulation data as input. We have calculated the composition of the target and substrate for several deposition conditions. The simulations predict a reduced compound coverage of the target in HiPIMS compared to the continuous dc sputtering regime which explains the increased deposition rate. The simulations show that an increased dissociation of oxygen in a HiPIMS discharge is beneficial to achieve stoichiometric films on the substrate at high deposition rates.

  19. Highly sensitive turn-on fluorescence detection of thrombomodulin based on fluorescence resonance energy transfer

    NASA Astrophysics Data System (ADS)

    Kong, Liyan; Zhu, Jiaming; Wang, Wen; Jin, Lehe; Fu, Yanjiao; Duan, Bohui; Tan, Liang

    2017-02-01

    As an integral glycoprotein on the surface of endothelial cells, thrombomodulin (TM) has very high affinity for thrombin. TM has been regarded to be a marker of endothelial damage since it can be released during endothelial cell injury. In this work, a highly sensitive fluorescence method for the quantitative detection of TM was developed. TM antibody (Ab) and bovine serum albumin (BSA) were bound on gold nanoparticles (AuNPs) to construct BSA-AuNPs-Ab nanocomposites and they were characterized by transmission electron microscope and UV-vis spectrophotometry. The fluorescence of acridine orange (AO) was quenched by the prepared gold nanocomposites based on fluorescence resonance energy transfer (FRET). In the presence of TM, the fluorescence was turned on due to the effective separation of AO from the surface of gold nanocomposites. Under optimum conditions, the enhanced fluorescence intensity displayed a linear relationship with the logarithm of the TM concentration from 0.1 pg mL- 1 to 5 ng mL- 1 with a low detection limit of 12 fg mL- 1. The release of soluble thrombomodulin (sTM) by the injured HUVEC-C cells in the presence of H2O2 was investigated using the proposed method. The released sTM content in the growth medium was found to be increased with the enhancement of contact time of the cells with H2O2.

  20. Development of Thermally Stable and Highly Fluorescent IR Dyes

    NASA Technical Reports Server (NTRS)

    Bu, Xiu R.

    2004-01-01

    Fluorophores are the core component in various optical applications such as sensors and probes. Fluorphores with low-energy or long wavelength emission, in particular, in NIR region, possess advantages of low interference and high sensitivity. In this study, we has explored several classes of imidazole-based compounds for NIR fluorescent properties and concluded: (1) thiazole-based imidazole compounds are fluorescent; (2) emission energy is tunable by additional donor groups; (3) they also possess impressive two- photon absorption properties; and (4) fluorescence emission can be induced by two- photon input. This report summarizes (1) synthesis of new series of fluorophore; (2) impact of electron-withdrawing groups on fluorescent property; (3) unique property of two-photon absorption; and (4) on-going development.

  1. Optically Modulated Fluorescence Bioimaging: Visualizing Obscured Fluorophores in High Background

    PubMed Central

    2015-01-01

    Conspectus Fluorescence microscopy and detection have become indispensible for understanding organization and dynamics in biological systems. Novel fluorophores with improved brightness, photostability, and biocompatibility continue to fuel further advances but often rely on having minimal background. The visualization of interactions in very high biological background, especially for proteins or bound complexes at very low copy numbers, remains a primary challenge. Instead of focusing on molecular brightness of fluorophores, we have adapted the principles of high-sensitivity absorption spectroscopy to improve the sensitivity and signal discrimination in fluorescence bioimaging. Utilizing very long wavelength transient absorptions of kinetically trapped dark states, we employ molecular modulation schemes that do not simultaneously modulate the background fluorescence. This improves the sensitivity and ease of implementation over high-energy photoswitch-based recovery schemes, as no internal dye reference or nanoparticle-based fluorophores are needed to separate the desired signals from background. In this Account, we describe the selection process for and identification of fluorophores that enable optically modulated fluorescence to decrease obscuring background. Differing from thermally stable photoswitches using higher-energy secondary lasers, coillumination at very low energies depopulates transient dark states, dynamically altering the fluorescence and giving characteristic modulation time scales for each modulatable emitter. This process is termed synchronously amplified fluorescence image recovery (SAFIRe) microscopy. By understanding and optically controlling the dye photophysics, we selectively modulate desired fluorophore signals independent of all autofluorescent background. This shifts the fluorescence of interest to unique detection frequencies with nearly shot-noise-limited detection, as no background signals are collected. Although the fluorescence

  2. High resolution 3D fluorescence tomography using ballistic photons

    NASA Astrophysics Data System (ADS)

    Zheng, Jie; Nouizi, Farouk; Cho, Jaedu; Kwong, Jessica; Gulsen, Gultekin

    2015-03-01

    We are developing a ballistic-photon based approach for improving the spatial resolution of fluorescence tomography using time-domain measurements. This approach uses early photon information contained in measured time-of-fight distributions originating from fluorescence emission. The time point spread functions (TPSF) from both excitation light and emission light are acquired with gated single photon Avalanche detector (SPAD) and time-correlated single photon counting after a short laser pulse. To determine the ballistic photons for reconstruction, the lifetime of the fluorophore and the time gate from the excitation profiles will be used for calibration, and then the time gate of the fluorescence profile can be defined by a simple time convolution. By mimicking first generation CT data acquisition, the sourcedetector pair will translate across and also rotate around the subject. The measurement from each source-detector position will be reshaped into a histogram that can be used by a simple back-projection algorithm in order to reconstruct high resolution fluorescence images. Finally, from these 2D sectioning slides, a 3D inclusion can be reconstructed accurately. To validate the approach, simulation of light transport is performed for biological tissue-like media with embedded fluorescent inclusion by solving the diffusion equation with Finite Element Method using COMSOL Multiphysics simulation. The reconstruction results from simulation studies have confirmed that this approach drastically improves the spatial resolution of fluorescence tomography. Moreover, all the results have shown the feasibility of this technique for high resolution small animal imaging up to several centimeters.

  3. Marine fluorescence from high spectrally resolved satellite measurements

    NASA Astrophysics Data System (ADS)

    Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

    2014-05-01

    When chlorophyll molecules absorb light, most of this energy is transformed into chemical energy in a process of photosynthesis. However, a fraction of the energy absorbed is reemitted as fluorescence. As a result of its relationship to photosynthetic e?ciency, information about chlorophyll fluorescence can be used to assess the physiological state of phytoplankton (Falkowski and Kolber,1995). In-situ measurements of chlorophyll fluorescence are widespread in physiological and ecophysiological studies. When retrieved from space, chlorophyll fluorescence can improve our knowledge of global biogeochemical cycles and phytoplankton productivity (Behrenfeld et al., 2009; Huot et al., 2013) by providing high coverage and periodicity. So far, the only satellite retrieval of sun-induced marine fluorescence, Fluorescence Line Height (FLH), was designed for MODIS (Abbott and Letelier, 1999), and later also applied to the similar sensor MERIS (Gower et al., 2004). However, it could so far not be evaluated on global scale. Here, we present a different approach to observe marine chlorophyll fluorescence, based on the Differential Optical Absorption Spectroscopy (DOAS) technique (Perner and Platt, 1979) applied to the hyperspectral data from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Global Ozone Monitoring Experiment-2 (GOME-2). Since fluorescence, as a trans-spectral process, leads to the shift of the wavelength of the radiation, it can be observed in the filling-in of Fraunhofer lines. In our retrieval, we evaluate the filling-in of the Zeeman triplet Fraunhofer line FeI at 684.3 nm, which is located very close to the emission peak of marine fluorescence (~685 nm). In order to conduct the chlorophyll fluorescence retrieval with the DOAS method, we calculated the reference spectra for chlorophyll fluorescence, based on simulations performed with the coupled ocean-atmosphere radiative transfer model SCIATRAN (Rozanov et al., 2014

  4. Metal–Dielectric Waveguides for High Efficiency Fluorescence Imaging

    PubMed Central

    Zhu, Liangfu; Zhang, Douguo; Wang, Ruxue; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Du, Luping; Yuan, Xiaocong; Lakowicz, Joseph R.

    2015-01-01

    We demonstrate that Metal–Dielectric Waveguide structures (MDWs) with high efficiency of fluorescence coupling can be suitable as substrates for fluorescence imaging. This hybrid MDWs consists of a continuous metal film and a dielectric top layer. The optical modes sustaining inside this structure can be excited with a high numerical aperture (N.A) objective, and then focused into a virtual optical probe with high intensity, leading to efficient excitation of fluorophores deposited on top of the MDWs. The emitted fluorophores couple with the optical modes thus enabling the directional emission, which is verified by the back focal plane (BFP) imaging. These unique properties of MDWs have been adopted in a scanning laser confocal optical microscopy, and show the merit of high efficiency fluorescence imaging. MDWs can be easily fabricated by vapor deposition and/or spin coating, the silica surface of the MDWs is suitable for biomolecule tethering, and will offer new opportunities for cell biology and biophysics research. PMID:26525494

  5. Synthesis of water-soluble CdSe quantum dots with various fluorescent properties and their application in immunoassay for determination of C-reactive protein.

    PubMed

    Gasparyan, V K

    2014-09-01

    Effects of various factors on synthesis and fluorescent properties of CdSe quantum dots were studied. It was shown that variation of pH, stabilizer and concentration of precursors brings to obtaining of quantum dots with various fluorescent properties. The nanoparticles prepared were conjugated with rabbit antibodies to C-Reactive protein and C-Reactive protein for competitive immunoassay for determination of CRP. It was shown that interaction of these dots as a result of antigen-antibody reaction brings to resonance energy transfer and these changes in fluorescence spectra correlate with concentration of CRP. This approach permits to determine CRP in range between 4-100 ng.

  6. The Hazards of Reactive Chemicals in High School Laboratories.

    ERIC Educational Resources Information Center

    Forlin, Peter

    Chemical reactivity is a major area of risk in high school laboratories. This paper reports on a study that has provided a research-based framework for risk management in Australian chemical education. The chemical practice model of risk management is considered with respect to kinetic factors; catalysts; concentrations and proportions;…

  7. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    NASA Astrophysics Data System (ADS)

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-11-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  8. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    PubMed Central

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-01-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions. PMID:25394493

  9. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide.

    PubMed

    Nagarkar, Sanjog S; Saha, Tanmoy; Desai, Aamod V; Talukdar, Pinaki; Ghosh, Sujit K

    2014-11-14

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  10. Analyses of herpes simplex virus type 1 latency and reactivation at the single cell level using fluorescent reporter mice.

    PubMed

    Proença, J T; Nelson, D; Nicoll, M P; Connor, V; Efstathiou, S

    2016-03-01

    Herpes simplex virus type 1 (HSV-1) establishes a latent infection in sensory neurons from which the virus can periodically reactivate. Whilst latency establishment is thought to result from a failure to express immediate-early genes, we have previously shown that subpopulations of the latent neuronal reservoir have undergone lytic promoter activation prior to latency establishment. In the present study, we have investigated the biological properties of such latently infected neuronal subpopulations using Ai6 fluorescent reporter mice. Using this system we have determined that prior ICP0 or TK promoter activation does not correlate with increased latent virus DNA loads within individual cells and that neurons with evidence of historical lytic cycle promoter activity exhibit a comparable frequency of reactivation to that of the general latent cell population. Comparison of viral DNA content within cells harbouring latent HSV-1 genomes and those undergoing the earliest stages of reactivation has revealed that reactivation can initiate from cells harbouring a wide range of HSV-1 genome copies, but that exiting latency is biased towards cells bearing higher latent virus DNA loads.

  11. Synthesis of belite cement clinker of high hydraulic reactivity

    SciTech Connect

    Kacimi, Larbi Simon-Masseron, Angelique Salem, Souria Ghomari, Abdelhamid Derriche, Zoubir

    2009-07-15

    This study is concerned with the increase of the cooling rate of belite clinker, by using the water quenching for the chemical stabilization of reactive belite, which improves the hydraulic properties of this clinker. The addition of adequate mineralizers, as NaF and Fe{sub 2}O{sub 3}, contributes to the improvement of the clinker properties obtained at low burning temperature. X-ray fluorescence spectroscopy, X-ray diffraction analysis and optical microscopy were used to determine the chemical and mineralogical compositions of this clinker. The samples were analyzed by means of a scanning electronic microscope connected with an energy-dispersive X-ray spectrometer to detect the composition of the belite phase and its morphology. Physical and mechanical properties of this clinker cement were determined. The results show that the belite clinker obtained at 1150 {sup o}C, with lime saturation factor 0.67, is characterized by a great hydraulic reactivity, similar to that of the ordinary alite clinker. The addition of 2% of NaF and the water quenching improved the chemical, mineralogical and structural properties, while improving the cement hydraulic properties.

  12. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  13. High-level fluorescence labeling of gram-positive pathogens.

    PubMed

    Aymanns, Simone; Mauerer, Stefanie; van Zandbergen, Ger; Wolz, Christiane; Spellerberg, Barbara

    2011-01-01

    Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb) promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10-50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration.

  14. 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.

  15. High-contrast fluorescence imaging based on the polarization dependence of the fluorescence enhancement using an optical interference mirror slide.

    PubMed

    Yasuda, Mitsuru; Akimoto, Takuo

    2015-01-01

    High-contrast fluorescence imaging using an optical interference mirror (OIM) slide that enhances the fluorescence from a fluorophore located on top of the OIM surface is reported. To enhance the fluorescence and reduce the background light of the OIM, transverse-electric-polarized excitation light was used as incident light, and the transverse-magnetic-polarized fluorescence signal was detected. As a result, an approximate 100-fold improvement in the signal-to-noise ratio was achieved through a 13-fold enhancement of the fluorescence signal and an 8-fold reduction of the background light.

  16. HIgh Rate X-ray Fluorescence Detector

    SciTech Connect

    Grudberg, Peter Matthew

    2013-04-30

    The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with

  17. Fluorescent biosensors for high throughput screening of protein kinase inhibitors.

    PubMed

    Prével, Camille; Pellerano, Morgan; Van, Thi Nhu Ngoc; Morris, May C

    2014-02-01

    High throughput screening assays aim to identify small molecules that interfere with protein function, activity, or conformation, which can serve as effective tools for chemical biology studies of targets involved in physiological processes or pathways of interest or disease models, as well as templates for development of therapeutics in medicinal chemistry. Fluorescent biosensors constitute attractive and powerful tools for drug discovery programs, from high throughput screening assays, to postscreen characterization of hits, optimization of lead compounds, and preclinical evaluation of candidate drugs. They provide a means of screening for inhibitors that selectively target enzymatic activity, conformation, and/or function in vitro. Moreover, fluorescent biosensors constitute useful tools for cell- and image-based, multiplex and multiparametric, high-content screening. Application of fluorescence-based sensors to screen large and complex libraries of compounds in vitro, in cell-based formats or whole organisms requires several levels of optimization to establish robust and reproducible assays. In this review, we describe the different fluorescent biosensor technologies which have been applied to high throughput screens, and discuss the prerequisite criteria underlying their successful application. Special emphasis is placed on protein kinase biosensors, since these enzymes constitute one of the most important classes of therapeutic targets in drug discovery.

  18. Highly fluorescent and biocompatible iridium nanoclusters for cellular imaging.

    PubMed

    Vankayala, Raviraj; Gollavelli, Ganesh; Mandal, Badal Kumar

    2013-08-01

    Highly fluorescent iridium nanoclusters were synthesized and investigated its application as a potential intracellular marker. The iridium nanoclusters were prepared with an average size of ~2 nm. Further, these nanoclusters were refluxed with aromatic ligands, such as 2,2'-binaphthol (BINOL) in order to obtain fluorescence properties. The photophysical properties of these bluish-green emitting iridium nanoclusters were well characterized by using UV-Visible, fluorescence and lifetime decay measurements. The emission spectrum for these nanoclusters exhibit three characteristic peaks at 449, 480 and 515 nm. The fluorescence quantum yield of BINOL-Ir NCs were estimated to be 0.36 and the molar extinction co-efficients were in the order of 10(6) M(-1)cm(-1). In vitro cytotoxicity studies in HeLa cells reveal that iridium nanoclusters exhibited good biocompatibility with an IC50 value of ~100 μg/ml and also showed excellent co-localization and distribution throughout the cytoplasm region without entering into the nucleus. This research has opened a new window in developing the iridium nanoparticle based intracellular fluorescent markers and has wide scope to act as biomedical nanocarrier to carry many biological molecules and anticancer drugs.

  19. Reactive oxygen species in photochemistry of the red fluorescent protein "Killer Red".

    PubMed

    Vegh, Russell B; Solntsev, Kyril M; Kuimova, Marina K; Cho, Soohee; Liang, Yue; Loo, Bernard L W; Tolbert, Laren M; Bommarius, Andreas S

    2011-05-07

    The fluorescent protein aptly named "Killer Red" (KRed) is capable of killing transfected cells and inactivating fused proteins upon exposure to visible light in the presence of oxygen. We have investigated the source of the bioactive species through a variety of photophysical and photochemical techniques. Our results indicate a Type I (electron transfer mediated) photosensitizing mechanism.

  20. Structure-reactivity relationships between fluorescent chromophores and antioxidant activity of grain and sweet sorghum seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenolic structures, such as tannins, are the putative cause of a variety of seed functions including bird/insect resistance and antioxidant activity. Structure-reactivity relationships are necessary to understand the influence of polyphenolic chromophore structures on the tannin content and fr...

  1. A Simple Visualization of Double Bond Properties: Chemical Reactivity and UV Fluorescence

    ERIC Educational Resources Information Center

    Grayson, Scott M.

    2012-01-01

    A simple, easily visualized thin-layer chromatography (TLC) staining experiment is presented that highlights the difference in reactivity between aromatic double bonds and nonaromatic double bonds. Although the stability of aromatic systems is a major theme in organic chemistry, the concept is rarely reinforced "visually" in the undergraduate…

  2. Quantitative high dynamic range beam profiling for fluorescence microscopy

    SciTech Connect

    Mitchell, T. J. Saunter, C. D.; O’Nions, W.; Girkin, J. M.; Love, G. D.

    2014-10-15

    Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly within the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.

  3. Investigation of reactive transport with closed-flow column experiments and parallel factor analysis (PARAFAC) of fluorescence data

    NASA Astrophysics Data System (ADS)

    Ritschel, Thomas; Totsche, Kai Uwe

    2013-04-01

    The sorption of solutes and colloids to immobile sorbents results in the phenomenon of retardation. Besides the interactions at the sorbent-solution-interface, the sorption rate depends also on the spatial structure of the pore network (size distribution, connectivity, topology). Column experiments allow for the consideration of the structure and thus for a quantification of possible rate limitations. We focus on column experiments run in closed-flow mode. There, a typical oscillation in the "breakthrough" of solute concentration, which conveys additional information about the flow regime (dispersivity, water content, immobile water) as well as the effective interaction kinetics, can be observed. Another major feature of the closed flow design is the conservation of tracer mass inside the column setup. Therefore, the investigation of sorption characteristics can be simplified by using mass balances. Our objective is to study the interaction between different solutes (conservative tracers, e.g., NaCl or LiBr and reactive tracers, e.g., acetate, oxalate and phenanthrene) and artificial porous media (composed of quartz, illite, goethite and charcoal in a well defined grain size distribution). The concentration-time profile of solutes is measured with non-consuming techniques (fluorescence spectroscopy or electrical conductivity measurements). PARAFAC analysis of fluorescence data is used for the quantification of aromatic compounds in complex background solutions. Interaction parameters obtained from breakthrough data are then used to quantify the availability of reactive mineral surfaces and effective rates of physical and chemical non-equilibrium processes. After the column experiments, the effect on the microtopology and mineral surfaces is investigated by atomic force microscopy and scanning electron microscopy. Recent multi-step tracer experiments allowed for the reconstruction of adsorption isotherms of oxalate and acetate on goethite.

  4. Detection of c-reactive protein based on a magnetic immunoassay by using functional magnetic and fluorescent nanoparticles in microplates.

    PubMed

    Yang, S F; Gao, B Z; Tsai, H Y; Fuh, C Bor

    2014-11-07

    We report the preparation and application of biofunctional nanoparticles to detect C-reactive protein (CRP) in magnetic microplates. A CRP model biomarker was used to test the proposed detection method. Biofunctional magnetic nanoparticles, CRP, and biofunctional fluorescent nanoparticles were used in a sandwich nanoparticle immunoassay. The CRP concentrations in the samples were deduced from the reference plot, using the fluorescence intensity of the sandwich nanoparticle immunoassay. When biofunctional nanoparticles were used to detect CRP, the detection limit was 1.0 ng ml(-1) and the linear range was between 1.18 ng ml(-1) and 11.8 μg ml(-1). The results revealed that the method involving biofunctional nanoparticles exhibited a lower detection limit and a wider linear range than those of the enzyme-linked immunosorbent assay (ELISA) and most other methods. For CRP measurements of serum samples, the differences between this method and ELISA in CRP measurements of serum samples were less than 13%. The proposed method can reduce the analysis time to one-third that of ELISA. This method demonstrates the potential to replace ELISA for rapidly detecting biomarkers with a low detection limit and a wide dynamic range.

  5. Time resolved ion energy distribution functions of non-reactive and reactive high power impulse magnetron sputtering of titanium

    NASA Astrophysics Data System (ADS)

    Grosse, Katharina; Breilmann, Wolfgang; Maszl, Christian; Benedikt, Jan; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique for thin film deposition and can be operated in reactive and non-reactive mode. The growth rate of HiPIMS in non-reactive mode reduces to 30% compared to direct current magnetron sputtering (dcMS) at same average power. However, the quality of the coatings produced with HiPIMS is excellent which makes these plasmas highly appealing. In reactive mode target poisoning is occurring which changes the plasma dynamics. An advantage of reactive HiPIMS is that it can be operated hysteresis-free which can result in a higher growth rate compared to dcMS. In this work thin films are deposited by a HiPIMS plasma which is generated by short pulses of 100 μs with high power densities in the range of 1 kW/cm2. Ar and Ar/N2 admixtures are used as a working gas to sputter a 2'' titanium target. The particle transport is analysed with time resolved ion energy distribution functions which are measured by a mass spectrometer with a temporal resolution of 2 μs. Phase resolved optical emission spectroscopy is executed to investigate the particle dynamics of different species. The time and energy resolved particle fluxes in non-reactive and reactive mode are compared and implications on the sputter process are discussed.

  6. Highly fluorescent resorcinarene cavitand nanocapsules with efficient renal clearance

    NASA Astrophysics Data System (ADS)

    Mahadevan, Kalpana; Patthipati, Venkata Suresh; Han, Sangbum; Swanson, R. James; Whelan, Eoin C.; Osgood, Christopher; Balasubramanian, Ramjee

    2016-08-01

    Nanomaterial based imaging approaches hold substantial promise in addressing current diagnostic and therapeutic challenges. One of the key requirements for the successful clinical translation of nanomaterials is their complete clearance from the body within a reasonable time period preferably via the renal filtration route. This article describes the synthesis of highly fluorescent, water soluble, resorcinarene cavitand nanocapsules and demonstrates their effective renal clearance in mice. The synthesis and functionalization of nanocapsules was accomplished in a one-pot operation via thiol-ene reactions without involving self-assembly, sacrificial templates or emulsions. Water soluble resorcinarene cavitand nanocapsules obtained by this approach were covalently functionalized with Alexa Fluor 750. Highly fluorescent nanocapsules with hydrodynamic diameters of 122 nm and 68 nm and extinction coefficients of 1.3 × 109 M-1 cm-1 and 1.5 × 108 M-1 cm-1 respectively were prepared by varying the reaction conditions. The in vivo biodistribution and clearance of these nanocapsules in mice followed by whole-body fluorescence imaging showed that they were both cleared renally within a few hours. Given the inherent encapsulation capabilities of nanocapsules, the renal clearance demonstrated in this work opens up new opportunities for their theranostic applications especially for targeting and treating the urinary tract.

  7. Highly fluorescent resorcinarene cavitand nanocapsules with efficient renal clearance.

    PubMed

    Mahadevan, Kalpana; Patthipati, Venkata Suresh; Han, Sangbum; Swanson, R James; Whelan, Eoin C; Osgood, Christopher; Balasubramanian, Ramjee

    2016-08-19

    Nanomaterial based imaging approaches hold substantial promise in addressing current diagnostic and therapeutic challenges. One of the key requirements for the successful clinical translation of nanomaterials is their complete clearance from the body within a reasonable time period preferably via the renal filtration route. This article describes the synthesis of highly fluorescent, water soluble, resorcinarene cavitand nanocapsules and demonstrates their effective renal clearance in mice. The synthesis and functionalization of nanocapsules was accomplished in a one-pot operation via thiol-ene reactions without involving self-assembly, sacrificial templates or emulsions. Water soluble resorcinarene cavitand nanocapsules obtained by this approach were covalently functionalized with Alexa Fluor 750. Highly fluorescent nanocapsules with hydrodynamic diameters of 122 nm and 68 nm and extinction coefficients of 1.3 × 10(9) M(-1) cm(-1) and 1.5 × 10(8) M(-1) cm(-1) respectively were prepared by varying the reaction conditions. The in vivo biodistribution and clearance of these nanocapsules in mice followed by whole-body fluorescence imaging showed that they were both cleared renally within a few hours. Given the inherent encapsulation capabilities of nanocapsules, the renal clearance demonstrated in this work opens up new opportunities for their theranostic applications especially for targeting and treating the urinary tract.

  8. Containerless high temperature property measurements by atomic fluorescence

    NASA Technical Reports Server (NTRS)

    Nordine, P. C.; Schiffman, R. A.

    1982-01-01

    Laser induced fluorescence techniques were developed for the containerless study of high temperature processes, material properties, levitation, and heating techniques for containerless earth-based experimentation. Experiments were performed in which fluorescence of atomic aluminum, mercury, or tungsten were studied. These experiments include measurements of: (1) Al atom evaporation from CW CO2 laser heated and aerodynamically levitated sapphire and alumina spheres, and self-supported sapphire filaments, (2) Al atom reaction with ambient oxygen in the wake of a levitated specimen, (3) Hg atom concentrations in the wake of levitated alumina and sapphire spheres, relative to the ambient Hg atom concentration, (4) Hg atom concentrations in supersonic levitation jets, and (5) metastable, electronically excited W atom concentrations produced by evaporation of an electrically heated tungsten filament.

  9. Fluorescence encoded super resolution imaging based on a location estimation algorithm for high-density fluorescence probes

    NASA Astrophysics Data System (ADS)

    Nishimura, Takahiro; Kimura, Hitoshi; Ogura, Yusuke; Tanida, Jun

    2016-11-01

    In this paper, we propose a fluorescence encoded super resolution technique based on an estimation algorithm to determine locations of high-density fluorescence emitters. In our method, several types of fluorescence coded probes are employed to reduce densities of target molecules labeled with individual codes. By applying an estimation algorithm to each coded image, the locations of the high density probes can be determined. Due to multiplexed fluorescence imaging, this approach will provide fast super resolution microscopy. In experiments, we evaluated the performance of the method using probes with different fluorescence wavelengths. Numerical simulation results show that the locations of probes with the density of 200 μ m^{-2} , which is a typical membrane-receptor expression level, are determined with acquisition of 16 different coded images.

  10. X‐ray Excited Optical Fluorescence and Diffraction Imaging of Reactivity and Crystallinity in a Zeolite Crystal: Crystallography and Molecular Spectroscopy in One

    PubMed Central

    Ristanović, Zoran; Hofmann, Jan P.; Richard, Marie‐Ingrid; Jiang, Tao; Chahine, Gilbert A.; Schülli, Tobias U.; Meirer, Florian

    2016-01-01

    Abstract Structure–activity relationships in heterogeneous catalysis are challenging to be measured on a single‐particle level. For the first time, one X‐ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm‐resolved X‐ray diffraction (μ‐XRD) and X‐ray excited optical fluorescence (μ‐XEOF) maps of the crystallinity and Brønsted reactivity of a zeolite crystal previously reacted with a styrene probe molecule. The local gradients in chemical reactivity (derived from μ‐XEOF) were correlated with local crystallinity and framework Al content, determined by μ‐XRD. Two distinctly different types of fluorescent species formed selectively, depending on the local zeolite crystallinity. The results illustrate the potential of this approach to resolve the crystallographic structure of a porous material and its reactivity in one experiment via X‐ray induced fluorescence of organic molecules formed at the reactive centers. PMID:27145171

  11. X‐ray Excited Optical Fluorescence and Diffraction Imaging of Reactivity and Crystallinity in a Zeolite Crystal: Crystallography and Molecular Spectroscopy in One

    PubMed Central

    Ristanović, Zoran; Hofmann, Jan P.; Richard, Marie‐Ingrid; Jiang, Tao; Chahine, Gilbert A.; Schülli, Tobias U.; Meirer, Florian

    2016-01-01

    Abstract Structure–activity relationships in heterogeneous catalysis are challenging to be measured on a single‐particle level. For the first time, one X‐ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm‐resolved X‐ray diffraction (μ‐XRD) and X‐ray excited optical fluorescence (μ‐XEOF) maps of the crystallinity and Brønsted reactivity of a zeolite crystal previously reacted with a styrene probe molecule. The local gradients in chemical reactivity (derived from μ‐XEOF) were correlated with local crystallinity and framework Al content, determined by μ‐XRD. Two distinctly different types of fluorescent species formed selectively, depending on the local zeolite crystallinity. The results illustrate the potential of this approach to resolve the crystallographic structure of a porous material and its reactivity in one experiment via X‐ray induced fluorescence of organic molecules formed at the reactive centers. PMID:27478278

  12. Containerless high temperature property measurements by atomic fluorescence

    NASA Technical Reports Server (NTRS)

    Schiffman, R. A.; Walker, C. A.

    1984-01-01

    Laser induced fluorescence (LIF) techniques for containerless study of high temperature processes and material properties was studied. Gas jet and electromagnetic levitation and electromagnetic and laser heating techniques are used with LIF in earth-based containerless high temperature experiments. Included are the development of an apparatus and its use in the studies of (1) chemical reactions on Al2O3, molybdenum, tungsten and LaB6 specimens, (2) methods for noncontact specimen temperature measurement, (3) levitation jet properties and (4) radiative lifetime and collisional energy transfer rates for electronically excited atoms.

  13. Containerless high temperature property measurements by atomic fluorescence

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The use of laser induced fluorescence (LIF) techniques for containerless study of high temperature processes and material properties is studied. Gas jet and electromagnetic levitation and electromagnetic and laser heating techniques are used with LIF in Earth-based containerless high temperature experiments. The work to date includes development of an apparatus and its use in studies of chemical reactions on Al2O3, molybdenum, and tungsten specimens, novel methods for noncontact specimen temperature measurement, and levitation jet properties. Brief summaries of these studies are given. The apparatus is described and detailed results for the current reporting period are presented.

  14. High-pressure reactivity of L,L-lactide.

    PubMed

    Ceppatelli, Matteo; Frediani, Marco; Bini, Roberto

    2011-03-17

    L,L-Lactide, a dimer of L-lactic acid, is the typical monomer used for the catalytic synthesis of poly(L-lactic acid) (PLLA). We studied its phase diagram and reactivity at high pressure and high temperature by means of a diamond anvil cell. FTIR and Raman spectroscopy were employed to probe the changes occurring in the sample. An increase of temperature at pressure higher than 0.1 GPa revealed a solid-solid phase transition before the melting. A reaction was observed immediately after the melting with the almost complete transformation of the starting reactant to an amorphous poly(lactic acid) (PLA). The increase of pressure was found to accelerate the process, suggesting the reaction rate to be limited in the diffusion step. A steeper acceleration, likely due to multiphoton absorption processes of the 647.1 nm laser light by PLA, was observed in the Raman experiments.

  15. Simultaneous Correlative Scanning Electron and High-NA Fluorescence Microscopy

    PubMed Central

    Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Effting, Andries P. J.; Voorneveld, Philip W.; Lucas, Miriam S.; Hardwick, James C.; Wepf, Roger A.; Kruit, Pieter; Hoogenboom, Jacob P.

    2013-01-01

    Correlative light and electron microscopy (CLEM) is a unique method for investigating biological structure-function relations. With CLEM protein distributions visualized in fluorescence can be mapped onto the cellular ultrastructure measured with electron microscopy. Widespread application of correlative microscopy is hampered by elaborate experimental procedures related foremost to retrieving regions of interest in both modalities and/or compromises in integrated approaches. We present a novel approach to correlative microscopy, in which a high numerical aperture epi-fluorescence microscope and a scanning electron microscope illuminate the same area of a sample at the same time. This removes the need for retrieval of regions of interest leading to a drastic reduction of inspection times and the possibility for quantitative investigations of large areas and datasets with correlative microscopy. We demonstrate Simultaneous CLEM (SCLEM) analyzing cell-cell connections and membrane protrusions in whole uncoated colon adenocarcinoma cell line cells stained for actin and cortactin with AlexaFluor488. SCLEM imaging of coverglass-mounted tissue sections with both electron-dense and fluorescence staining is also shown. PMID:23409024

  16. High-pressure SANS and fluorescence unfolding study of calmodulin.

    PubMed

    Gibrat, Gabriel; Hoa, Gaston Hui Bon; Craescu, Constantin T; Assairi, Liliane; Blouquit, Yves; Annighöfer, Burkhard; May, Roland P; Bellissent-Funel, Marie-Claire

    2014-09-01

    Apo-calmodulin, a small soluble mainly α protein, is a calcium-dependent protein activator. Calcium binding affects the calmodulin conformation but also its stability. Calcium free form unfolds between 40 and 80°C, whereas the calcium-saturated form is stable up to temperatures as high as 100°C, forbidding comparison of the thermal unfolding pathways of the two forms. Thus, this paper focuses especially on the conformation of pressure-induced unfolding states of both forms of calmodulin, by combining small-angle neutron scattering (SANS) with biophysical techniques such as tyrosines and ANS fluorescence. In contrast to heat denaturation (Gibrat et al., BBA, 2012), the pressure denaturation of calmodulin is reversible up to pressures of 3000bar (300MPa). A pressure-induced compact intermediate state has been found for the two calmodulin forms, but their unfolding pathways are different. A domain compaction and an increase of the ANS fluorescence of holo form have been evidenced. On the contrary, a domain dilatation and an ANS fluorescence decrease have been found for the apo form. The pressure induced an increase of the interdomain distance for both calmodulin forms, suggesting that the central linker of calmodulin is flexible in solution.

  17. High-spatial-resolution nanoparticle x-ray fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Larsson, Jakob C.; Vâgberg, William; Vogt, Carmen; Lundström, Ulf; Larsson, Daniel H.; Hertz, Hans M.

    2016-03-01

    X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 μm), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.

  18. High-speed tomographic PIV and OH PLIF measurements in turbulent reactive flows

    NASA Astrophysics Data System (ADS)

    Coriton, Bruno; Steinberg, Adam M.; Frank, Jonathan H.

    2014-06-01

    High-speed tomographic particle image velocimetry (TPIV) is demonstrated in turbulent reactive flows at acquisition rates ranging from 10 to 16 kHz. The 10-kHz TPIV measurements are combined with planar laser-induced fluorescence (PLIF) imaging of OH to mark the high-temperature reaction zone of the flame. Simultaneous TPIV/OH PLIF measurements are applied to the stabilization region of a weakly turbulent lifted dimethyl ether (DME)/air jet flame ( Re D = 7,600) and the mixing layer of a turbulent partially premixed DME/air jet flame ( Re D = 29,300). In the lifted jet flame, vortical structures exhibit time-dependent morphological changes and eventually dissipate as they approach the flame. In the near field of the turbulent jet flame, dynamics of localized extinction are captured as coherent structures with high compressive strain rates interact with the reaction zone and subsequently break apart. The principal axis of compressive strain has a strong preferential orientation at 45° with respect to the jet axis. The three-dimensional velocity field measurements are used to evaluate biases in two-dimensional (2D) measurements of compressive strain rates in a turbulent jet flame. The biases in the 2D measurements primarily stem from out-of-plane orientation of the principal axis of compressive strain. Comparisons with a constant density turbulent non-reactive jet ( Re D = 22,600) show that the jet flame has larger coherent structures that are confined near the reaction zone. Data from the non-reactive jet are also used to evaluate effects of noise, bias, and spatial averaging on measurements of the velocity and velocity gradients.

  19. Kinetic characterization of factor Xa binding using a quenched fluorescent substrate based on the reactive site of factor Xa inhibitor from Bauhinia ungulata seeds.

    PubMed

    Oliva, M L V; Andrade, S A; Juliano, M A; Sallai, R C; Torquato, R J; Sampaio, M U; Pott, V J; Sampaio, C A M

    2003-07-01

    The specific Kunitz Bauhinia ungulata factor Xa inhibitor (BuXI) and the Bauhinia variegata trypsin inhibitor (BvTI) blocked the activity of trypsin, chymotrypsin, plasmin, plasma kallikrein and factor XIIa, and factor Xa inhibition was achieved only by BuXI (K(i) 14 nM). BuXI and BvTI are highly homologous (70%). The major differences are the methionine residues at BuXI reactive site, which are involved in the inhibition, since the oxidized protein no longer inhibits factor Xa but maintains the trypsin inhibition. Quenched fluorescent substrates based on the reactive site sequence of the inhibitors were synthesized and the kinetic parameters of the hydrolysis were determined using factor Xa and trypsin. The catalytic efficiency k(cat)/K(m) 4.3 x 10(7) M(-1)sec(>-1) for Abz-VMIAALPRTMFIQ-EDDnp (lead peptide) hydrolysis by factor Xa was 10(4)-fold higher than that of Boc-Ile-Glu-Gly-Arg-AMC, widely used as factor Xa substrate. Lengthening of the substrate changed its susceptibility to factor Xa hydrolysis. Both methionine residues in the substrate influence the binding to factor Xa. Serine replacement of threonine (P(1)') decreases the catalytic efficiency by four orders of magnitude. Factor Xa did not hydrolyze the substrate containing the reactive site sequence of BvTI, that inhibits trypsin inhibitor but not factor Xa. Abz-VMIAALPRTMFIQ-EDDnp prolonged both the prothrombin time and the activated partial thromboplastin time, and the other modified substrates used in this experiment altered blood-clotting assays.

  20. Measurements of OH and HO2 Radicals and OH Reactivity at Tropical Locations Using Laser-Induced Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Furneaux, K. L.; Whalley, L. K.; Edwards, P.; Goddard, A.; Ingham, T.; Evans, M. J.; Heard, D. E.

    2009-04-01

    The OH radical is the dominant daytime oxidant in the atmosphere. Together with the closely coupled HO2 radical, these two species (termed HOx) play an important role in determining the composition of the atmosphere. Tropical latitudes are active regions of atmospheric chemistry due to high solar radiation, humidity and temperature. For these reasons, field measurements of HOx in the tropics are crucial to improve understanding of atmospheric chemistry through model - measurement comparisons. Due to the low number of HOx measurements in the tropics, these comparisons are sparse. An aircraft campaign over the pristine Amazon rainforest found HOx concentrations to be high1,2. It has been proposed that this is due to a previously overlooked OH recycling mechanism via the oxidation of isoprene1,2. The need to determine if this is ubiquitous across tropical rainforest regions is necessary. The Leeds FAGE instrument was deployed at the Bukit Atur Global Atmospheric Watch Station, Borneo (5.0N, 117.8E) from April - July 2008 as part of the OP3 project (Oxidant and Particle Photochemical Processes above a South-East Asian tropical rainforest) to measure OH and HO2 concentrations and the OH chemical lifetime by Fluorescence Assay by Gas Expansion (FAGE). These measurements represent the first ground based [HOx] measurements in a tropical rainforest. Chemical activity differed significantly throughout the measurement period. HOx concentrations were elevated in July (average peak [OH] = 5.3 ×106 molecule cm-3) compared to April (average peak [OH] = 2.5 ×106 molecule cm-3), attributed to higher OH sinks in April. Measurements of the OH chemical lifetime can be used to quantify unknown OH sinks. The OH chemical lifetime displayed a diurnal cycle that correlated with isoprene concentrations. At this site isoprene represents the major OH loss route but there are significant unknown fractions. Model calculations result in an under prediction of HOx when measured sinks are

  1. Sulfur-doped graphene quantum dots as a novel fluorescent probe for highly selective and sensitive detection of Fe(3+).

    PubMed

    Li, Shuhua; Li, Yunchao; Cao, Jun; Zhu, Jia; Fan, Louzhen; Li, Xiaohong

    2014-10-21

    Sulfur-doped graphene quantum dots (S-GQDs) with stable blue-green fluorescence were synthesized by one-step electrolysis of graphite in sodium p-toluenesulfonate aqueous solution. Compared with GQDs, the S-GQDs drastically improved the electronic properties and surface chemical reactivities, which exhibited a sensitive response to Fe(3+). Therefore, the S-GQDs were used as an efficient fluorescent probe for highly selective detection of Fe(3+). Upon increasing of Fe(3+) concentration ranging from 0.01 to 0.70 μM, the fluorescence intensity of S-GQDs gradually decreased and reached a plateau at 0.90 μM. The difference in the fluorescence intensity of S-GQDs before and after adding Fe(3+) was proportional to the concentration of Fe(3+), and the calibration curve displayed linear regions over the range of 0-0.70 μM. The detection limit was 4.2 nM. Finally, this novel fluorescent probe was successfully applied to the direct analysis of Fe(3+) in human serum, which presents potential applications in clinical diagnosis and may open a new way to the design of effective fluorescence probes for other biologically related targets.

  2. Immunoanalytical characteristics of C-reactive protein and high sensitivity C-reactive protein.

    PubMed

    Moutachakkir, Mariame; Lamrani Hanchi, Asma; Baraou, Azzedine; Boukhira, Abderrahman; Chellak, Saliha

    2017-04-01

    C-reactive protein (CRP) is a polypeptide molecule belonging to the family of pentraxins. It has a molecular mass of 120,000 daltons and consists of five identical sub-units that contain each 206 amino acids. CRP is synthesized primarily by the liver in response to certain pro-inflammatory cytokines. It plays an important role in innate immunity, opsonization by its properties, complement activation and immunoglobulins receptor binding. CRP is a protein of the acute systemic inflammation and is, therefore, a prime marker of inflammation. As atherosclerosis has an inflammatory component, CRP can appreciate cardiovascular risk when analysed by more sensitive assays, that are able to measure extremely low concentrations of CRP, called high sensitivity CRP (hs-CRP). The CRP is quantified by immunonephelometry or immunoturbidimetry. There is no standard technique. The hs-CRP quantification is based on immunonephelemetry sensitized techniques called "immunolatex". We present in this paper the main biochemical and physiological data related to CRP, explaining the need for its quantification, the problems encountered in immunoassay and the interpretation of results.

  3. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  4. Highly reactive free radicals in electronic cigarette aerosols.

    PubMed

    Goel, Reema; Durand, Erwann; Trushin, Neil; Prokopczyk, Bogdan; Foulds, Jonathan; Elias, Ryan J; Richie, John P

    2015-09-21

    Electronic cigarette (EC) usage has increased exponentially, but limited data are available on its potential harmful effects. We tested for the presence of reactive, short-lived free radicals in EC aerosols by electron paramagnetic resonance spectroscopy (EPR) using the spin-trap phenyl-N-tert-butylnitrone (PBN). Radicals were detected in aerosols from all ECs and eliquids tested (2.5 × 10(13) to 10.3 × 10(13) radicals per puff at 3.3 V) and from eliquid solvents propylene glycol and glycerol and from "dry puffing". These results demonstrate, for the first time, the production of highly oxidizing free radicals from ECs which may present a potential toxicological risk to EC users.

  5. The Gray Institute 'open' high-content, fluorescence lifetime microscopes.

    PubMed

    Barber, P R; Tullis, I D C; Pierce, G P; Newman, R G; Prentice, J; Rowley, M I; Matthews, D R; Ameer-Beg, S M; Vojnovic, B

    2013-08-01

    We describe a microscopy design methodology and details of microscopes built to this 'open' design approach. These demonstrate the first implementation of time-domain fluorescence microscopy in a flexible automated platform with the ability to ease the transition of this and other advanced microscopy techniques from development to use in routine biology applications. This approach allows easy expansion and modification of the platform capabilities, as it moves away from the use of a commercial, monolithic, microscope body to small, commercial off-the-shelf and custom made modular components. Drawings and diagrams of our microscopes have been made available under an open license for noncommercial use at http://users.ox.ac.uk/~atdgroup. Several automated high-content fluorescence microscope implementations have been constructed with this design framework and optimized for specific applications with multiwell plates and tissue microarrays. In particular, three platforms incorporate time-domain FLIM via time-correlated single photon counting in an automated fashion. We also present data from experiments performed on these platforms highlighting their automated wide-field and laser scanning capabilities designed for high-content microscopy. Devices using these designs also form radiation-beam 'end-stations' at Oxford and Surrey Universities, showing the versatility and extendibility of this approach.

  6. Location change method for imaging chemical reactivity and catalysis with single-molecule and -particle fluorescence microscopy.

    PubMed

    Blum, S A

    2014-08-21

    In the last eight years, it has become possible to image chemical reactivity at the single-molecule and -particle level with fluorescence microscopy. This Perspective describes one of the imaging techniques that enabled this state-of-the-art application: imaging by the location change of molecules and particles. In this method, the microscope and experiment are configured to produce a signal when an individual molecule or particle changes location or changes mobility concurrently with a chemical change. This imaging technique has enabled observation of single chemical reactions and unraveled mechanisms of complex chemical and physical processes in transition metal and polymerization systems. This Perspective has three major goals: (1) to unify studies of different chemical processes or of different chemical questions, which, in spite of these differences, employ a similar microscopy detection method, (2) to explain the technique to nonexperts and those who might be interested in joining this nascent field, and (3) to highlight unique information available through this cross-disciplinary technique and the value this information has for chemical reaction development generally and catalysis specifically. To this end, application of the location change method to the investigation of polymerization reactions with radical initiators and separately with metal catalysts, and to ligand exchange reactions at platinum complexes are described.

  7. Rapidly responsive and highly selective fluorescent probe for sulfite detection in real samples and living cells.

    PubMed

    Li, Hongda

    2015-10-15

    Sulfites (HSO3(-) or SO3(-)) have very significant toxicity in the environment and in the system. However, developing specific identification of sulfite probes is still very important. In this paper, a highly selective colorimetric and fluorescent probe (HHC) was synthesized to detect HSO3(-) in real samples and living cells. Sensing performance and preponderance are listed as follows. First, probe HHC showed remarkable selectivity for HSO3(-) over varieties of other species, including cysteine, glutathione, S(2-), CN(-), and reactive oxygen species, mainly because of the introduction of the electron-poor C=C double bond for HSO3(-). Second, probe HHC has great molar absorptivity, allowing it to act as a visual detection of probe for HSO3(-). Third, the fluorescence intensities of HHC linearly correlate with the concentration of HSO3(-), with a detection limit of 6.8 nm. Finally, our proposed probe can be applied to the visually determination of trace HSO3(-) in real samples and living HeLa cells with high precision. We hope that our proposed probe will greatly benefit biological sciences when biological researchers survey the role of HSO3(-) in biological systems.

  8. Fluorescent nanodiamonds as highly stable biomarker for endotoxin verification

    NASA Astrophysics Data System (ADS)

    Bergmann, Thorsten; Burg, Jan Michael; Lilholt, Maria; Maeder, Ulf; Beer, Sebastian; Salzig, Denise; Ebrahimi, Mehrdad; Czermak, Peter; Fiebich, Martin

    2012-03-01

    Fluorescent nanodiamonds (ND) provide advantageous properties as a fluorescent biomarker for in vitro and in vivo studies. The maximum fluorescence occurs around 700 nm, they do not show photobleaching or blinking and seem to be nontoxic. After a pretreatment with strong acid fluorescent ND can be functionalized and coupled to endotoxin. Endotoxin is a decay product of bacteria and causes strong immune reactions. Therefore endotoxin has to be removed for most applications. An effective removal procedure is membrane filtration. The endotoxin, coupled to fluorescent ND can be visualized by using confocal microscopy which allows the investigation of the separation mechanisms of the filtration process within the membranes.

  9. Red phosphors for use in high CRI fluorescent lamps

    DOEpatents

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

    2005-11-15

    Novel red emitting phosphors for use in fluorescent lamps resulting in superior color rendering index values compared to conventional red phosphors. Also disclosed is a fluorescent lamp including a phosphor layer comprising blends of one or more of a blue phosphor, a blue-green phosphor, a green phosphor and a red a phosphor selected from the group consisting of SrY.sub.2 O.sub.4 :Eu.sup.3+, (Y,Gd)Al.sub.3 B.sub.4 O.sub.12 :Eu.sup.3+, and [(Y.sub.1-x-y-m La.sub.y)Gd.sub.x ]BO.sub.3 :Eu.sub.m wherein y<0.50 and m=0.001-0.3. 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 the disclosed red phosphors 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.

  10. Highly efficient fluorescence sensing with hollow core photonic crystal fibers.

    PubMed

    Smolka, Stephan; Barth, Michael; Benson, Oliver

    2007-10-01

    We investigate the potential of microstructured optical fibers (MOFs) for highly sensitive absorption and fluorescence measurements by infiltrating a dye solution in the holey structure. Generally in a MOF only the evanescent part of the electromagnetic field penetrates into the sample material, providing a weak light-matter interaction. We compare such a MOF with a selectively filled hollow core photonic crystal fiber (HCPCF), in which most of the field energy propagates in the sample material. We show that dye concentrations down to 1x10(-10) M can be detected in a HCPCF using only nanoliter sample volumes. Our experiments proof that HCPCFs are well suited for demanding sensing applications, outperforming existing fiber tools that rely on evanescent sensing.

  11. Modeling of the Reactive High Power Impulse Magnetron Sputtering (HiPIMS) process

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Raadu, Michael; Brenning, Nils; Minea, Tiberiu

    2015-09-01

    Reactive high power impulse magnetron sputtering (HiPIMS) provides both a high ionization fraction of the sputtered material and a high dissociation fraction of the molecular gas. We demonstrate this through an ionization region model (IRM) of the reactive Ar/O2 HiPIMS discharge with a titanium target. We explore the influence of oxygen dilution on the discharge properties such as electron density, the ionization fraction of the sputtered vapor and the oxygen dissociation fraction. We discuss the important processes and challenges for more detailed modeling of the reactive HiPIMS discharge. Furthermore, we discuss experimental observations during reactive high power impulse magnetron sputtering sputtering (HiPIMS) of Ti target in Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on the reactive gas flow rate, pulse repetition frequency and discharge voltage. The discharge current increases with decreasing repetition frequency and increasing flowrate of the reactive gas.

  12. Time-resolved fluorescence spectroscopy of high-lying electronic states of Zn-tetraphenylporphyrin

    NASA Astrophysics Data System (ADS)

    Gurzadyan, G. G.; Tran-Thi, T.-H.; Gustavsson, T.

    1998-01-01

    Depopulation of the S2 excited electronic state of the Zn-tetraphenylporphyrin (ZnTPP) was monitored by measuring the decay of S2→S0 and the rise of S1→S0 fluorescence using the up-conversion fluorescence technique with a time-resolution of 120 fs. The lifetime of the S2 electronic state, measured for ZnTPP in ethanol (τS2=2.35 ps) correlates with the risetime of S1→S0 fluorescence. This result demonstrates the depopulation of S2 to S1 via (vibrational) states with lifetimes much shorter than that of S2. The rise time of S2 fluorescence (τv=60-90 fs) was attributed to vibrational relaxation (in S2). Fluorescence anisotropy decay of the S2 state was also studied by measuring the parallel and perpendicular fluorescence components. The high initial anisotropy of r⩾0.7 is interpreted as due to the existence of a degenerate excited electronic state S2 and the corresponding fast decay time τ1=0.2 ps to the electronic dephasing of the degenerate level pair. The long component of the anisotropy decay (τ2≫10 ps) is due to rotational diffusion.

  13. High rate reactive sputtering of MoN(x) coatings

    NASA Technical Reports Server (NTRS)

    Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

    1991-01-01

    High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

  14. Assessment of reactivity transient experiments with high burnup fuel

    SciTech Connect

    Ozer, O.; Yang, R.L.; Rashid, Y.R.; Montgomery, R.O.

    1996-03-01

    A few recent experiments aimed at determining the response of high-burnup LWR fuel during a reactivity initiated accident (RIA) have raised concerns that existing failure criteria may be inappropriate for such fuel. In particular, three experiments (SPERT CDC-859, NSRR HBO-1 and CABRI REP Na-1) appear to have resulted in fuel failures at only a fraction of the anticipated enthalpy levels. In evaluating the results of such RIA simulation experiments, however, it is necessary that the following two key considerations be taken into account: (1) Are the experiments representative of conditions that LWR fuel would experience during an in-reactor RIA event? (2) Is the fuel that is being utilized in the tests representative of the present (or anticipated) population of LWR fuel? Conducting experiments under conditions that can not occur in-reactor can trigger response modes that could not take place during in-reactor operation. Similarly, using unrepresentative fuel samples for the tests will produce failure information that is of limited relevance to commercial LWR fuel. This is particularly important for high-burnup fuel since the manner under which the test samples are base-irradiated prior to the test will impact the mechanical properties of the cladding and will therefore affect the RIA response. A good example of this effect can be seen in the results of the SPERT CDC-859 test and in the NSRR JM-4 and JM-5 tests. The conditions under which the fuel used for these tests was fabricated and/or base-irradiated prior to the RIA pulse resulted in the formation of multiple cladding defects in the form of hydride blisters. When this fuel was subjected to the RIA power pulse, it failed by developing multiple cracks that were closely correlated with the locations of the pre-existing hydride blisters. In the case of the JM tests, many of the cracks formed within the blisters themselves and did not propagate beyond the heavily hydrided regions.

  15. High reactivity of ancient permafrost carbon upon hydrological release

    NASA Astrophysics Data System (ADS)

    Vonk, J. E.; Mann, P. J.; Davydov, S.; Davydova, A.; Sobczak, W. V.; Schade, J.; Bulygina, E.; Zimov, S.; Spencer, R. G. M.; Eglinton, T. I.; Holmes, R. M.

    2012-04-01

    Half of the global stock of soil organic carbon (OC) is stored in Arctic permafrost. About one third of this pool consists of so-called yedoma, organic-rich deposits that were formed during the Pleistocene. Previous studies show rapid respiration of yedoma upon thawing, with the potential release of large quantities of relict OC into the contemporary C cycle. The fluvial and coastal reactivity and fate of this OC, however, remain unclear. Duvannyi Yar is a well-studied yedoma exposure on the banks of Kolyma River in Northeastern Siberia. It can serve as a model for the >7000 km long East Siberian Arctic coastline that is dominated by similarly exposed yedoma cliffs, and is increasingly vulnerable to erosion with climate warming-induced decreases in sea-ice, and increases in storms and wave-fetch. Permafrost thaw on the Duvannyi Yar exposure produces thaw streams that are heavily loaded with freshly thawed yedoma sediments (suspended load ca. 650 g/L; particulate OC ca. 8-10 g/L; dissolved OC ca. 150-300 mg/L). We traced organic carbon loss and oxygen utilisation during incubations of Duvannyi Yar stream water, and a series of dilutions of Duvannyi Yar water and Kolyma River and East Siberian Sea water. Concurrent measurements of enzyme activities were taken to investigate the processes limitating degradation. The overall goal of the study was to investigate the relative bioavailability of contemporary versus ancient organic carbon pools over short time scales (days-weeks). Radiocarbon ages of the dissolved OC in the thaw streams were 19-29 ky BP, and particulate OC 19-38 ky BP. These ages are far older than any previously published values and clearly illustrate the mobilization of ancient permafrost organic matter into the contemporary carbon cycle. Incubation experiments showed that the ancient dissolved OC was highly susceptible to degradation, losing 34% of its carbon in 14 days (and 41% in 28 days). River and ocean water samples spiked with ancient carbon

  16. Soluble, highly fluorescent variants of green fluorescent protein (GFP) for use in higher plants.

    PubMed

    Davis, S J; Vierstra, R D

    1998-03-01

    Green fluorescent protein (GFP) from Aequorea victoria has rapidly become a standard reporter in many biological systems. However, the use of GFP in higher plants has been limited by aberrant splicing of the corresponding mRNA and by protein insolubility. It has been shown that GFP can be expressed in Arabidopsis thaliana after altering the codon usage in the region that is incorrectly spliced, but the fluorescence signal is weak, possibly due to aggregation of the encoded protein. Through site-directed mutagenesis, we have generated a more soluble version of the codon-modified GFP called soluble-modified GFP (smGFP). The excitation and emission spectra for this protein are nearly identical to wild-type GFP. When introduced into A. thaliana, greater fluorescence was observed compared to the codon-modified GFP, implying that smGFP is 'brighter' because more of it is present in a soluble and functional form. Using the smGFP template, two spectral variants were created, a soluble-modified red-shifted GFP (smRS-GFP) and a soluble-modified blue-fluorescent protein (smBFP). The increased fluorescence output of smGFP will further the use of this reporter in higher plants. In addition, the distinct spectral characters of smRS-GFP and smBFP should allow for dual monitoring of gene expression, protein localization, and detection of in vivo protein-protein interactions.

  17. Discovery of a novel family of polycyclic aromatic molecules with unique reactivity and members valuable for fluorescent sensing and medicinal chemistry.

    PubMed

    Xiao, Yi; Liu, Fengyu; Chen, Zhuo; Zhu, Weipin; Xu, Yufang; Qian, Xuhong

    2015-04-18

    A novel polycyclic aromatic molecule, i.e. 1-oxo-1H-phenalene-2,3-dicarbonitrile (compound 1, initially misidentified as 8-oxo-8H-acenaphtho[1,2-b]pyrrolecarbonitrile) was discovered by our group in 2005. This parent compound is highlighted for its unique oxidative S(N)Ar(H) (nucleophilic substitution of aromatic hydrogen) reactivity that provides easy approaches to diverse derivatives with different long-wavelength fluorescence and important biological activities. To date, a large number of derivatives have been synthesized and evaluated by several international research groups, indicating the formation of a new and valuable family of functional chemicals. Some members have been functionalized for molecular or nanoparticle-based probes applicable in chemical and environmental sensing, biomolecule imaging and tumor diagnosis. Others have qualified as high potency anticancer agents specifically targeting different functional proteins in tumor cells. With regard to the increasing attention paid to this new chemical family, it is a good time to review major achievements in order to promote further and deeper investigation.

  18. The influence of a reactive element on the growth of a thermally grown chromia scale : a grazing emission x-ray fluorescence study.

    SciTech Connect

    Koshelev, I. K.; Paulikas, A. P.; Uran, S.; Beno, M. B.; Jennings, G.; Linton, J.; Veal, B. W.; Materials Science Division

    2003-06-01

    The oxidation of 55Fe-25Cr-20Ni (wt.%) alloys, with and without added reactive element (RE) Y, were studied using grazing-emission X-ray fluorescence (GEXRF). Samples were studied after isothermal treatments at 750 C in O2 and after cyclic-oxidation treatments. In early-stage oxidation, a Ni-rich scale is formed. The distribution of this early-stage Ni deposit is studied as the scale evolves. The Ni deposit, serving as a marker, remains on the outer scale surface in Y-containing alloys, but is not detectable in scales on Y-free alloys. The results indicate that new chromia scale growth occurs at the outer surface in Y-free alloys but, for Y-containing alloys, new growth occurs away from the outer surface. Thus, a shift in the growth mode is apparently observed at 750 C, consistent with higher-temperature observations. However, unlike the high-temperature measurements, scale-growth rates are not significantly affected by the RE.

  19. Highly photostable, reversibly photoswitchable fluorescent protein with high contrast ratio for live-cell superresolution microscopy

    PubMed Central

    Zhang, Xi; Zhang, Mingshu; Li, Dong; He, Wenting; Peng, Jianxin; Betzig, Eric; Xu, Pingyong

    2016-01-01

    Two long-standing problems for superresolution (SR) fluorescence microscopy are high illumination intensity and long acquisition time, which significantly hamper its application for live-cell imaging. Reversibly photoswitchable fluorescent proteins (RSFPs) have made it possible to dramatically lower the illumination intensities in saturated depletion-based SR techniques, such as saturated depletion nonlinear structured illumination microscopy (NL-SIM) and reversible saturable optical fluorescence transition microscopy. The characteristics of RSFPs most critical for SR live-cell imaging include, first, the integrated fluorescence signal across each switching cycle, which depends upon the absorption cross-section, effective quantum yield, and characteristic switching time from the fluorescent “on” to “off” state; second, the fluorescence contrast ratio of on/off states; and third, the photostability under excitation and depletion. Up to now, the RSFPs of the Dronpa and rsEGFP (reversibly switchable EGFP) families have been exploited for SR imaging. However, their limited number of switching cycles, relatively low fluorescence signal, and poor contrast ratio under physiological conditions ultimately restrict their utility in time-lapse live-cell imaging and their ability to reach the desired resolution at a reasonable signal-to-noise ratio. Here, we present a truly monomeric RSFP, Skylan-NS, whose properties are optimized for the recently developed patterned activation NL-SIM, which enables low-intensity (∼100 W/cm2) live-cell SR imaging at ∼60-nm resolution at subsecond acquisition times for tens of time points over broad field of view. PMID:27562163

  20. High-Resolution Single-Molecule Fluorescence Imaging of Zeolite Aggregates within Real-Life Fluid Catalytic Cracking Particles**

    PubMed Central

    Ristanović, Zoran; Kerssens, Marleen M; Kubarev, Alexey V; Hendriks, Frank C; Dedecker, Peter; Hofkens, Johan; Roeffaers, Maarten B J; Weckhuysen, Bert M

    2015-01-01

    Fluid catalytic cracking (FCC) is a major process in oil refineries to produce gasoline and base chemicals from crude oil fractions. The spatial distribution and acidity of zeolite aggregates embedded within the 50–150 μm-sized FCC spheres heavily influence their catalytic performance. Single-molecule fluorescence-based imaging methods, namely nanometer accuracy by stochastic chemical reactions (NASCA) and super-resolution optical fluctuation imaging (SOFI) were used to study the catalytic activity of sub-micrometer zeolite ZSM-5 domains within real-life FCC catalyst particles. The formation of fluorescent product molecules taking place at Brønsted acid sites was monitored with single turnover sensitivity and high spatiotemporal resolution, providing detailed insight in dispersion and catalytic activity of zeolite ZSM-5 aggregates. The results point towards substantial differences in turnover frequencies between the zeolite aggregates, revealing significant intraparticle heterogeneities in Brønsted reactivity. PMID:25504139

  1. High-throughput screening with micro-x-ray fluorescence

    SciTech Connect

    Havrilla, George J.; Miller, Thomasin C.

    2005-06-15

    Micro-x-ray fluorescence (MXRF) is a useful characterization tool for high-throughput screening of combinatorial libraries. Due to the increasing threat of use of chemical warfare (CW) agents both in military actions and against civilians by terrorist extremists, there is a strong push to improve existing methods and develop means for the detection of a broad spectrum of CW agents in a minimal amount of time to increase national security. This paper describes a combinatorial high-throughput screening technique for CW receptor discovery to aid in sensor development. MXRF can screen materials for elemental composition at the mesoscale level (tens to hundreds of micrometers). The key aspect of this work is the use of commercial MXRF instrumentation coupled with the inherent heteroatom elements within the target molecules of the combinatorial reaction to provide rapid and specific identification of lead species. The method is demonstrated by screening an 11-mer oligopeptide library for selective binding of the degradation products of the nerve agent VX. The identified oligopeptides can be used as selective molecular receptors for sensor development. The MXRF screening method is nondestructive, requires minimal sample preparation or special tags for analysis, and the screening time depends on the desired sensitivity.

  2. High-throughput screening with micro-x-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Havrilla, George J.; Miller, Thomasin C.

    2005-06-01

    Micro-x-ray fluorescence (MXRF) is a useful characterization tool for high-throughput screening of combinatorial libraries. Due to the increasing threat of use of chemical warfare (CW) agents both in military actions and against civilians by terrorist extremists, there is a strong push to improve existing methods and develop means for the detection of a broad spectrum of CW agents in a minimal amount of time to increase national security. This paper describes a combinatorial high-throughput screening technique for CW receptor discovery to aid in sensor development. MXRF can screen materials for elemental composition at the mesoscale level (tens to hundreds of micrometers). The key aspect of this work is the use of commercial MXRF instrumentation coupled with the inherent heteroatom elements within the target molecules of the combinatorial reaction to provide rapid and specific identification of lead species. The method is demonstrated by screening an 11-mer oligopeptide library for selective binding of the degradation products of the nerve agent VX. The identified oligopeptides can be used as selective molecular receptors for sensor development. The MXRF screening method is nondestructive, requires minimal sample preparation or special tags for analysis, and the screening time depends on the desired sensitivity.

  3. Containerless high temperature property measurements by atomic fluorescence

    NASA Technical Reports Server (NTRS)

    Nordine, Paul C.; Shiffman, Robert A.

    1987-01-01

    Containerless high temperature processing and material property measurements are discussed. Researchers developed methods for non-contact suspension, heating, and property measurement for materials at temperatures up to 3,680K, the melting point of tungsten. New, scientifically interesting results were obtained in Earth-based research. These results and the demonstration of new methods and techniques form a basis for further advances under the low gravity environment of space where containerless conditions are more easily achieved. Containerless high temperature material property investigations that have been completed in this and our earlier projects include measurements of fluorine LaB sub 6 reaction kinetics at 1,000 to 1,500K; optical property measurements on sapphire (Al2O3) at temperatures up to the melting point (2,327K); and vapor pressure measurements for LaB sub 6 at 2,000 to 2,500K, for molybdenum up to 2,890K and for tungsten up to 3,680K. Gas jet levitation which is applicable to any solid material, and electromagnetic levitation of electrical conductors were used to suspend the materials of interest. Non-contact heating and property measurements were achieved by optical techniques, i.e., laser heating, laser induced fluorescence measurements of vapor concentrations, and optical pyrometry for specimen temperatures.

  4. High-resolution whole field fluorescence lifetime imaging of fluorophore distribution and environment

    NASA Astrophysics Data System (ADS)

    Dayel, Mark J.; Dowling, Keith; Hyde, Sam C. W.; Dainty, Christopher; French, Paul M. W.; Vourdas, P.; Lever, M. J.; Dymoke-Bradshaw, Anthony K. L.; Hares, Jonathan D.; Kellett, Paul A.

    1998-01-01

    We report the development of a high temporal resolution fluorescence lifetime imaging (FLIM) system suing a time- gated image intensifier to provide whole field FLIM images. The gate width has been optimized to 110 ps, and changes in the environment of a fluorescent phantom, causing lifetime differences of 20 ps, have been detected. Environmental changes of the fluorescent indicator, Lucifer Yellow, have been sensed by measuring changes in its fluorescence lifetime in the presence of the protein albumin. We also present provisional fluorescence lifetime images of tissue constituents.

  5. High-precision metrology of highly charged ions via relativistic resonance fluorescence.

    PubMed

    Postavaru, O; Harman, Z; Keitel, C H

    2011-01-21

    Resonance fluorescence of laser-driven highly charged ions is investigated with regard to precisely measuring atomic properties. For this purpose an ab initio approach based on the Dirac equation is employed that allows for studying relativistic ions. These systems provide a sensitive means to test correlated relativistic dynamics, quantum electrodynamic phenomena and nuclear effects by applying x-ray lasers. We show how the narrowing of sidebands in the x-ray fluorescence spectrum by interference due to an additional optical driving can be exploited to determine atomic dipole or multipole moments to unprecedented accuracy.

  6. Peer Relations and Peer Deviance as Predictors of Reactive and Proactive Aggression among High School Girls

    ERIC Educational Resources Information Center

    Uz Bas, Asli; Öz Soysal, Fatma Selda

    2016-01-01

    This study aimed to investigate associations between reactive and proactive aggression and peer relations and peer deviance among high school girls. A total of 442 high school students participated in this study. Reactive-Proactive Aggression Questionnaire, the Peer Relations Scale, and the Peer Deviance Scale were used to collect data. Results…

  7. Atomic fluorescence study of high temperature aerodynamic levitation

    NASA Technical Reports Server (NTRS)

    Nordine, P. C.; Schiffman, R. A.; Sethi, D. S.

    1982-01-01

    Ultraviolet laser induced atomic fluorescence has been used to characterize supersonic jet aerodynamic levitation experiments. The levitated specimen was a 0.4 cm sapphire sphere that was separately heated at temperatures up to 2327 K by an infrared laser. The supersonic jet expansion and thermal gradients in the specimen wake were studied by measuring spatial variations in the concentration of atomic Hg added to the levitating argon gas stream. Further applications of atomic fluorescence in containerless experiments, such as ideal gas fluorescence thermometry and containerless process control are discussed.

  8. Cerebrovascular reactivity alterations in asymptomatic high school football players.

    PubMed

    Svaldi, Diana O; Joshi, Chetas; Robinson, Meghan E; Shenk, Trey E; Abbas, Kausar; Nauman, Eric A; Leverenz, Larry J; Talavage, Thomas M

    2015-01-01

    Cerebrovascular reactivity (CVR) is impaired following brain injury, increasing susceptibility to subsequent injury. CVR was tracked in football and non-collision athletes throughout one season. CVR transiently decreased in football athletes during the first half of the season. Results indicate the brain adapts slowly to increases in loading, increasing risk for injury.

  9. [Determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography with fluorescence detector].

    PubMed

    Jiao, Yanna; Ding, Li; Zhu, Shaohua; Fu, Shanliang; Gong, Qiang; Li, Hui; Wang, Libing

    2013-01-01

    A method for the determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography (HPLC) with fluorescence detector was developed. The samples were extracted with trichloromethane by sonication for 30 min at 40 degrees C. The HPLC method was performed on a column of Eclipse XDB-C18 (250 mm x 4.6 mm, 5 microm) by gradient elution using 5 mmol/L ammonium acetate and acetonitrile as the mobile phases, and detected by the fluorescence detector at an excitation wavelength of 350 nm and an emission wavelength of 430 nm. The experimental results indicated that the four fluorescent whitening agents were separated well. The limits of detection (LOD) (S/N = 3) were 0.3, 0.1, 0.05, 0.14 mg/L, and the limits of quantification (LOQ) (S/N = 10) were 1.0, 0.4, 0.2, 0.5 mg/L for 1,4-bis (4-cyanostyryl) benzene (C. I. 199), 1,4-bis (2-benzoxazolyl) naphthalene (C. I. 367), 4,4'-bis(2-methoxystyryl) biphenyl (C. I. 378) and 2,5-thiophenediylbis (5-tert-butyl-1,3-benzoxazole) (C. I. 184), respectively. Good linearities with correlation coefficients (r2) not less than 0.991 were obtained. The proposed method is simple, accurate, sensitive and can meet the requirements of the routine determination of fluorescent whitening agents in entry-exit products.

  10. Using fluorescence-based microplate assay to assess DOM-metal binding in reactive materials for treatment of acid mine drainage.

    PubMed

    Neculita, Carmen Mihaela; Dudal, Yves; Zagury, Gerald J

    2011-01-01

    One potential drawback of compost-based passive bioreactors, which is a promising biotechnology for acid mine drainage (AMD) treatment, is the transport of dissolved organic matter (DOM)-metal complexes in surface waters. To address this problem, the objective of this study was to assess the maximum capacity of organic substrates to release soluble DOM-metal complexes in treated water. The reactivities of DOM in maple wood chips and sawdust, composted poultry manure, and leaf compost were quantified toward Cd2+, Ni2+, Fe2+, and Cu2+ using fluorescence quenching. The DOM showed the highest reactivity toward Fe, but a limited number of available sites for sorption, whereas DOM-Cd complexes exhibited the lowest fluorescence quenching. Overall, the DOM from a mixture of wastes formed higher concentrations of DOM-metal complexes relative to sole substrates. Among DOM-metal complexes, the concentrations of DOM-Ni complexes were the highest. After reaching steady-state, low concentrations of DOM-metal complexes were released in treated water, which is in agreement with theoretical predictions based on geochemical modeling. Therefore, in addition to physicochemical characterization, fluorescence quenching technique is recommended for the substrate selection of bioreactors.

  11. A CMOS In-Pixel CTIA High Sensitivity Fluorescence Imager

    PubMed Central

    Murari, Kartikeya; Etienne-Cummings, Ralph; Thakor, Nitish; Cauwenberghs, Gert

    2012-01-01

    Traditionally, charge coupled device (CCD) based image sensors have held sway over the field of biomedical imaging. Complementary metal oxide semiconductor (CMOS) based imagers so far lack sensitivity leading to poor low-light imaging. Certain applications including our work on animal-mountable systems for imaging in awake and unrestrained rodents require the high sensitivity and image quality of CCDs and the low power consumption, flexibility and compactness of CMOS imagers. We present a 132×124 high sensitivity imager array with a 20.1 μm pixel pitch fabricated in a standard 0.5 μ CMOS process. The chip incorporates n-well/p-sub photodiodes, capacitive transimpedance amplifier (CTIA) based in-pixel amplification, pixel scanners and delta differencing circuits. The 5-transistor all-nMOS pixel interfaces with peripheral pMOS transistors for column-parallel CTIA. At 70 fps, the array has a minimum detectable signal of 4 nW/cm2 at a wavelength of 450 nm while consuming 718 μA from a 3.3 V supply. Peak signal to noise ratio (SNR) was 44 dB at an incident intensity of 1 μW/cm2. Implementing 4×4 binning allowed the frame rate to be increased to 675 fps. Alternately, sensitivity could be increased to detect about 0.8 nW/cm2 while maintaining 70 fps. The chip was used to image single cell fluorescence at 28 fps with an average SNR of 32 dB. For comparison, a cooled CCD camera imaged the same cell at 20 fps with an average SNR of 33.2 dB under the same illumination while consuming over a watt. PMID:23136624

  12. High throughput assay for evaluation of reactive carbonyl scavenging capacity☆

    PubMed Central

    Vidal, N.; Cavaille, J.P.; Graziani, F.; Robin, M.; Ouari, O.; Pietri, S.; Stocker, P.

    2014-01-01

    Many carbonyl species from either lipid peroxidation or glycoxidation are extremely reactive and can disrupt the function of proteins and enzymes. 4-hydroxynonenal and methylglyoxal are the most abundant and toxic lipid-derived reactive carbonyl species. The presence of these toxics leads to carbonyl stress and cause a significant amount of macromolecular damages in several diseases. Much evidence indicates trapping of reactive carbonyl intermediates may be a useful strategy for inhibiting or decreasing carbonyl stress-associated pathologies. There is no rapid and convenient analytical method available for the assessment of direct carbonyl scavenging capacity, and a very limited number of carbonyl scavengers have been identified to date, their therapeutic potential being highlighted only recently. In this context, we have developed a new and rapid sensitive fluorimetric method for the assessment of reactive carbonyl scavengers without involvement glycoxidation systems. Efficacy of various thiol- and non-thiol-carbonyl scavenger pharmacophores was tested both using this screening assay adapted to 96-well microplates and in cultured cells. The scavenging effects on the formation of Advanced Glycation End-product of Bovine Serum Albumin formed with methylglyoxal, 4-hydroxynonenal and glucose-glycated as molecular models were also examined. Low molecular mass thiols with an α-amino-β-mercaptoethane structure showed the highest degree of inhibitory activity toward both α,β-unsaturated aldehydes and dicarbonyls. Cysteine and cysteamine have the best scavenging ability toward methylglyoxal. WR-1065 which is currently approved for clinical use as a protective agent against radiation and renal toxicity was identified as the best inhibitor of 4-hydroxynonenal. PMID:24688895

  13. Rational design, synthesis and characterization of highly fluorescent optical switches for high-contrast optical lock-in detection (OLID) imaging microscopy in living cells

    PubMed Central

    Petchprayoon, Chutima; Yan, Yuling; Mao, Shu; Marriott, Gerard

    2010-01-01

    A major challenge in cell biology is to elucidate molecular mechanisms that underlie the spatio-temporal control of cellular processes. These studies require microscope imaging techniques and associated optical probes that provide high-contrast and high-resolution images of specific proteins and their complexes. Auto-fluorescence however, can severely compromise image contrast and represents a fundamental limitation for imaging proteins within living cells. We have previously shown that optical switch probes and optical lock-in detection (OLID) image microscopy improve image contrast in high background environments. Here, we present the design, synthesis and characterization of amino- reactive and cell permeable optical switches that integrate the highly fluorescent fluorophore, tetramethylrhodamine (TMR) and spironaphthoxazine (NISO), a highly efficient optical switch. The NISO moiety in TMR-NISO undergoes rapid and reversible, excited-state driven transitions between a colorless spiro (SP)-state and a colored merocyanine (MC)-state in response to irradiation with 365 nm and >530 nm light. In the MC-state, the TMR (donor) emission is almost completely extinguished by Förster resonance energy transfer (FRET) to the MC probe (acceptor), whereas in the colorless SP-state, the quantum yield for TMR fluorescence is maximal. Irradiation of TMR-NISO with a defined sequence of 365 nm and 546 nm manipulates the levels of SP and MC with concomitant modulation of FRET efficiency and the TMR fluorescence signal. High fidelity optical switching of TMR fluorescence is shown for TMR-NISO probes in vitro and for membrane permeable TMR-NISO within living cells. PMID:20674372

  14. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    NASA Astrophysics Data System (ADS)

    Hoffman, A. S.; Debefve, L. M.; Bendjeriou-Sedjerari, A.; Ould-Chikh, S.; Bare, Simon R.; Basset, J.-M.; Gates, B. C.

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  15. Ionic Liquids and Ionizing Radiation: Reactivity of Highly Energetic Species

    SciTech Connect

    Wishart, J.F.

    2010-11-04

    Due to their unique properties, ionic liquids present many opportunities for basic research on the interactions of radiation with materials under conditions not previously available. At the same time, there are practical applied reasons for characterizing, understanding, and being able to predict how ionic-liquid-based devices and industrial-scale systems will perform under conditions of extreme reactivity, including radiation. This perspective discusses current issues in ionic liquid physical chemistry, provides a brief introduction to radiation chemistry, draws attention to some key findings in ionic liquid radiation chemistry, and identifies some current hot topics and new opportunities.

  16. Evaluation of highly reactive mono-(meth)acrylates as reactive diluents for BisGMA-based dental composites

    PubMed Central

    Kilambi, Harini; Cramer, Neil B.; Schneidewind, Lauren H.; Shah, Parag; Stansbury, Jeffrey W.; Bowman, Christopher N.

    2009-01-01

    Objective This study evaluates the performance of highly reactive novel monomethacrylates characterized by various secondary moieties as reactive diluent alternatives to TEGDMA in BisGMA filled dental resins. We hypothesize that these monomers improve material properties and kinetics over TEGDMA because of their unique polymerization behavior. Methods The cure rates and final double bond conversion of the resins were measured using real-time FTIR spectroscopy. The glass transition temperature and storage modulus of the formed polymers were measured using dynamic mechanical analysis. Flexural modulus and flexural strength values were obtained using a three-point bending flexural test carried out with a MTS® 858 Mini Bionix system. Results Polymerization kinetics and polymer mechanical properties were evaluated for the novel resin composites. It was observed that upon the use of novel monomethacrylates as reactive diluents, polymerization kinetics increased by up to 3-fold accompanied by increases in the extent of cure from 5% to 13% as compared to the BisGMA/TEGDMA control. Polymer composites formed from resins of BisGMA/novel monomethacrylates exhibited comparable Tg values to the control, along with 27–37% reductions in the glass transition half widths indicating the formation of more homogeneous polymeric networks. The BisGMA/monomethacrylate formulations exhibited equivalent flexural modulus and flexural strength values relative to BisGMA/TEGDMA. Significance Formulations containing novel monovinyl methacrylates exhibit dramatically increased curing rates while also exhibiting superior or at least comparable composite polymer mechanical properties. Thus, these types of materials are attractive for use as reactive diluent alternatives to TEGDMA in dental formulations. PMID:18584862

  17. Highly Fluorescent Green Fluorescent Protein Chromophore Analogues Made by Decorating the Imidazolone Ring.

    PubMed

    Gutiérrez, Sara; Martínez-López, David; Morón, María; Sucunza, David; Sampedro, Diego; Domingo, Alberto; Salgado, Antonio; Vaquero, Juan J

    2015-12-14

    The synthesis and photophysical behavior of an unexplored family of green fluorescent protein (GFP)-like chromophore analogues is reported. The compound (Z)-4-(4-hydroxybenzylidene)-1-propyl-2-(propylamino)-1H-imidazol-5(4 H)-one (p-HBDNI, 2 a) exhibits significantly enhanced fluorescence properties relative to the parent compound (Z)-5-(4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one (p-HBDI, 1). p-HBDNI was considered as a model system and the photophysical properties of other novel 2-amino-3,5-dihydro-4H-imidazol-4-one derivatives were evaluated. Time-dependent DFT calculations were carried out to rationalize the results. The analogue AIDNI (2 c), in which the 4-hydroxybenzyl group of p-HBDNI was replaced by an azaindole group, showed improved photophysical properties and potential for cell staining. The uptake and intracellular distribution of 2 c in living cells was investigated by confocal microscopy imaging.

  18. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  19. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    NASA Technical Reports Server (NTRS)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  20. Characteristics of high quality sorbent for fluidized bed combustion and problems of maintaining uniform reactivity

    SciTech Connect

    Bain, R.J. . Dept. of Geology)

    1993-03-01

    Fluidized bed combustion of coal is considered one of the more promising clean coal technologies for the future. While much research has gone into the design and operation of FBC units, there is little concern for what characterizes a high quality sorbent and the source of such a sorbent. Carbonate rocks, limestone and dolomite, have been tested extensively as sorbents and primarily two rock characteristics appear to significantly control reactivity: composition and texture. Calcium carbonate is more reactive than magnesium carbonate where all other rock characteristics are the same. In considering texture, highest reactivity is measured for carbonate rocks which consist of homogeneous, euhedral crystals ranging in size from .05 to .2 mm and which possess uniform intercrystalline porosity. The most reactive material possesses both high calcium content, uniform microcrystalline texture and intercrystalline porosity, however, such material is not very abundant in nature and is not locally available to midcontinent facilities. Sucrosic dolomite, which possesses uniform microcrystalline texture and intercrystalline porosity has high rank reactivity. While this rock is quite common, it occurs as beds, generally less than twenty feet thick, interlayered with less reactive dolomite types. Therefore, without selective quarrying methods, production of sorbent with uniformly high reactivity will be impossible.

  1. High precision optical fiber fluorescent temperature measurement system and data processing

    NASA Astrophysics Data System (ADS)

    Wang, Yutian; Bo, Xiaoxu; Gui, Feifei

    2010-08-01

    Generally, the theoretical analysis of the fluorescent life time temperature measurement is based on the assumption of the exponential life time characteristic, but in practice, the actual curve of the fluorescence are different from exponential. This is the key-influence on the stability of the high precision fluorescent measurement system. The differences are analyzed base on the theoretical mechanism of fluorescent, and a cutting and normalized method is given to describe the degree of the non-exponent of the actual fluorescent curve defer from the exponential curve. Several kinds of typical fluorescence materials spectrum and its cutting and normalized experiment results verify this theoretical analysis. Some effective measures to improve the non-exponent of the system are taken and are applied to a temperature measurement system based on actual fluorescent curve analysis with resolution 0.1°C, precisions +/-0.2°C, and real-time calibration is carried on. Based the theory base and the actuality of fluorescence optical fiber temperature sensor, two methods about fluorescence decay time constant are proposed. In the mean time, the mathematic model has been formed and analysis, so that the different schemes are selected in different situation.

  2. Heterogeneous nano metal-organic framework fluorescence probe for highly selective and sensitive detection of hydrogen sulfide in living cells.

    PubMed

    Ma, Yu; Su, Hao; Kuang, Xuan; Li, Xiangyuan; Zhang, Tingting; Tang, Bo

    2014-11-18

    Hydrogen sulfide (H2S) has been regarded as the third important gaseous signaling molecule involved in human physiological and pathological processes. Due to the high reactive and diffusible properties of H2S, real-time detection of H2S fluctuations in living biological specimens is crucial. Here, we present a Cu(II)-metalated 3D porous nanoscale metal-organic framework (nano-MOF) {CuL[AlOH]2}n (PAC; H6L = meso-tetrakis(4-carboxylphenyl)porphyrin) and successfully employ this nano-MOF as a novel heterogeneous fluorescence probe for H2S detection. As far as we know, nano-MOFs have never been used as selective fluorescence probes for H2S detection. On the basis of the advantages of nano-MOF materials, this biocompatible nano-MOF probe exhibits rapid response, excellent selectivity, and hypotoxicity in in situ detection of H2S and represents the most sensitive fluorescence probe for selective H2S detection under physiological pH. In addition, confocal imaging was achieved successfully in living cells.

  3. A high-resolution mitochondria-targeting ratiometric fluorescent probe for detection of the endogenous hypochlorous acid

    NASA Astrophysics Data System (ADS)

    Zhou, Liyi; Lu, Dan-Qing; Wang, Qianqian; Hu, Shunqin; Wang, Haifei; Sun, Hongyan; Zhang, Xiaobing

    2016-09-01

    Hypochlorite anion, one of the biologically important reactive oxygen species, plays an essential role in diverse normal biochemical functions and abnormal pathological processes. Herein, an efficient high-resolution mitochondria-targeting ratiometric fluorescent probe for hypochlorous acid detection has been designed, synthesized and characterized. It is easily synthesized by the condensation reaction (Cdbnd C) of a 2-(2-hydroxyphenyl) quinazolin-4(3H)-one fluorophore and a cyanine group (mitochondria-targeting), which made the whole molecular a large Stokes shift (210 nm) and the two well-resolved emission peaks separated by 140 nm. As a result, it is considered as a good candidate for high resolution hypochlorous acid imaging in live cells. The ratiometric fluorescent probe exhibited outstanding features of high sensitivity, high selectivity, rapid response time (within 50 s), and excellent mitochondria-targeting ability. Moreover, the probe can also be successfully applied to imaging endogenously hypochlorous acid in the mitochondria of living cells with low cytotoxicity, and high resolution.

  4. Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus

    PubMed Central

    Priyamvada, Lalita; Quicke, Kendra M.; Hudson, William H.; Onlamoon, Nattawat; Sewatanon, Jaturong; Edupuganti, Srilatha; Pattanapanyasat, Kovit; Chokephaibulkit, Kulkanya; Mulligan, Mark J.; Wilson, Patrick C.; Ahmed, Rafi; Suthar, Mehul S.; Wrammert, Jens

    2016-01-01

    Zika virus (ZIKV) is an emerging mosquito-borne flavivirus of significant public health concern. ZIKV shares a high degree of sequence and structural homology compared with other flaviviruses, including dengue virus (DENV), resulting in immunological cross-reactivity. Improving our current understanding of the extent and characteristics of this immunological cross-reactivity is important, as ZIKV is presently circulating in areas that are highly endemic for dengue. To assess the magnitude and functional quality of cross-reactive immune responses between these closely related viruses, we tested acute and convalescent sera from nine Thai patients with PCR-confirmed DENV infection against ZIKV. All of the sera tested were cross-reactive with ZIKV, both in binding and in neutralization. To deconstruct the observed serum cross-reactivity in depth, we also characterized a panel of DENV-specific plasmablast-derived monoclonal antibodies (mAbs) for activity against ZIKV. Nearly half of the 47 DENV-reactive mAbs studied bound to both whole ZIKV virion and ZIKV lysate, of which a subset also neutralized ZIKV. In addition, both sera and mAbs from the dengue-infected patients enhanced ZIKV infection of Fc gamma receptor (FcγR)-bearing cells in vitro. Taken together, these findings suggest that preexisting immunity to DENV may impact protective immune responses against ZIKV. In addition, the extensive cross-reactivity may have implications for ZIKV virulence and disease severity in DENV-experienced populations. PMID:27354515

  5. p-Dimethylaminobenzaldehyde-reactive substances in tail tendon collagen of streptozotocin-diabetic rats: temporal relation to biomechanical properties and advanced glycation endproduct (AGE)-related fluorescence.

    PubMed

    Stefek, M; Gajdosik, A; Gajdosikova, A; Krizanova, L

    2000-11-15

    In the present work, pepsin digests of tail tendons from streptozotocin-diabetic rats were found to contain material that reacted rapidly at room temperature with p-dimethylaminobenzaldehyde (Ehrlich's reagent) to give an adduct with an absorbance spectrum characteristic of the Ehrlich chromogen of pyrrolic nature determined in ageing collagens. A significant correlation of the Ehrlich adduct with tendon mechanical strength and collagen fluorescence characteristic of advanced glycation endproducts was observed. Collagen content of the Ehrlich-positive material was found to be significantly elevated in tendons of diabetic rats compared with age-matched healthy controls. The results indicate that the p-dimethylaminobenzaldehyde-reactive pyrrole moieties may contribute to the increased cross-linking of diabetic matrix collagen. Profound inhibitory effect of aminoguanidine was observed, underlining the role of non-enzymatic mechanisms of advanced glycation in pyrrolisation and cross-linking of collagen exposed to hyperglycaemia. It is hypothesised that quantification of the p-dimethylaminobenzaldehyde-reactive material in matrix collagen may provide a tissue measure of integrated hyperglycaemia over prolonged periods of time. Further research is to assess the significance of p-dimethylaminobenzaldehyde-reactive substances in diabetic collagen tissues and to reveal their relationship to enzyme-mediated physiological pyrrolisation of ageing collagens.

  6. Impact of fluorine based reactive chemistry on structure and properties of high moment magnetic material

    SciTech Connect

    Yang, Xiaoyu Chen, Lifan; Han, Hongmei; Fu, Lianfeng; Sun, Ming; Liu, Feng; Zhang, Jinqiu

    2014-05-07

    The impact of the fluorine-based reactive ion etch (RIE) process on the structural, electrical, and magnetic properties of NiFe and CoNiFe-plated materials was investigated. Several techniques, including X-ray fluorescence, 4-point-probe, BH looper, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS), were utilized to characterize both bulk film properties such as thickness, average composition, Rs, ρ, Bs, Ms, and surface magnetic “dead” layers' properties such as thickness and element concentration. Experimental data showed that the majority of Rs and Bs changes of these bulk films were due to thickness reduction during exposure to the RIE process. ρ and Ms change after taking thickness reduction into account were negligible. The composition of the bulk films, which were not sensitive to surface magnetic dead layers with nano-meter scale, showed minimum change as well. It was found by TEM and EELS analysis that although both before and after RIE there were magnetic dead layers on the top surface of these materials, the thickness and element concentration of the layers were quite different. Prior to RIE, dead layer was actually native oxidation layers (about 2 nm thick), while after RIE dead layer consisted of two sub-layers that were about 6 nm thick in total. Sub-layer on the top was native oxidation layer, while the bottom layer was RIE “damaged” layer with very high fluorine concentration. Two in-situ RIE approaches were also proposed and tested to remove such damaged sub-layers.

  7. Static reactive power compensators for high-voltage power systems. Final report

    SciTech Connect

    Not Available

    1981-04-01

    A study conducted to summarize the role of static reactive power compensators for high voltage power system applications is described. This information should be useful to the utility system planning engineer in applying static var systems (SVS) to high voltage as (HVAC) systems. The static var system is defined as a form of reactive power compensator. The general need for reactive power compensation in HVAC systems is discussed, and the static var system is compared to other devices utilized to provide reactive power compensation. Examples are presented of applying SVS for specific functions, such as the prevention of voltage collapse. The operating principles of commercially available SVS's are discussed in detail. The perormance and active power loss characteristics of SVS types are compared.

  8. Highly integrated lab-on-a-chip for fluorescence detection

    NASA Astrophysics Data System (ADS)

    Guduru, Surya S. K.; Scotognella, Francesco; Chiasera, Alessandro; Sreeramulu, Valligatla; Criante, Luigino; Vishnubhatla, Krishna Chaitanya; Ferrari, Maurizio; Ramponi, Roberta; Lanzani, Guglielmo; Vázquez, Rebeca Martínez

    2016-09-01

    We report the fabrication and validation of a microfluidic chip for fluorescence detection, which incorporates in the same glass substrate the microfluidic network, the excitation, the filtering, and the collection elements. The device is fabricated in a hybrid approach combining different technologies, such as femtosecond laser micromachining and RF sputtering, to increase their individual capabilities. The validation of the chip demonstrates a good wavelength selective light filtering and a limit of detection of a 600-nM concentration of Oxazine 720 perchlorate dye.

  9. Fluorescent and high intensity discharge lamp use in chambers and greenhouses

    NASA Technical Reports Server (NTRS)

    Langhans, Robert W.

    1994-01-01

    Fluorescent and High Intensity Discharge lamps have opened up great opportunities for researchers to study plant growth under controlled environment conditions and for commercial growers to increase plant production during low/light periods. Specific technical qualities of fluorescent and HID lamps have been critically reviewed. I will direct my remarks to fluorescent and high intensity discharge (HID) lamps in growth chambers, growth rooms, and greenhouses. I will discuss the advantages and disadvantages of using each lamp in growth chambers, growth rooms and greenhouses.

  10. A high fatigue resistant, photoswitchable fluorescent spiropyran-polyoxometalate-BODIPY single-molecule.

    PubMed

    Saad, Ali; Oms, Olivier; Dolbecq, Anne; Menet, Clotilde; Dessapt, Rémi; Serier-Brault, Hélène; Allard, Emmanuel; Baczko, Krystyna; Mialane, Pierre

    2015-11-18

    The tuning of the fluorescence through the activation of the photochromic part in an unprecedented covalent spiropyran-polyoxometalate-BODIPY tricomponent points out the high photofatigue resistance of such molecular switches.

  11. Fluorescent QDs-polystyrene composite nanospheres for highly efficient and rapid protein antigen detection

    NASA Astrophysics Data System (ADS)

    Zhou, Changhua; Mao, Mao; Yuan, Hang; Shen, Huaibin; Wu, Feng; Ma, Lan; Li, Lin Song

    2013-09-01

    In this paper, high-quality carboxyl-functionalized fluorescent (red, green, and blue emitting) nanospheres (46-103 nm) consisting of hydrophobic quantum dots (QDs) and polystyrene were prepared by a miniemulsion polymerization approach. This miniemulsion polymerization approach induced a homogeneous distribution and high aqueous-phase transport efficiency of fluorescent QDs in composite nanospheres, which proved the success of our encoding QDs strategy. The obtained fluorescent nanospheres exhibited high stability in aqueous solution under a wide range of pH, different salt concentrations, PBS buffer, and thermal treatment at 80 °C. Based on the red emitting composite nanosphere, we performed fluorescent lateral flow immunoassay (LFIA) strips for high-sensitivity and rapid alpha-fetal protein detection. The detection limit reached 0.1 ng/mL, which was 200 times higher than commercial colloidal gold-labeled LFIA strips, and it reached similar detection level in enzyme-linked immunosorbent assay kit.

  12. Two-photon fluorescence correlation spectroscopy with high count rates and low background using dielectric microspheres

    PubMed Central

    Aouani, Heykel; Schön, Peter; Brasselet, Sophie; Rigneault, Hervé; Wenger, Jérôme

    2010-01-01

    Two-photon excitation fluorescence is a powerful technique commonly used for biological imaging. However, the low absorption cross section of this non-linear process is a critical issue for performing biomolecular spectroscopy at the single molecule level. Enhancing the two-photon fluorescence signal would greatly improve the effectiveness of this technique, yet current methods struggle with medium enhancement factors and/or high background noise. Here, we show that the two-photon fluorescence signal from single Alexa Fluor 488 molecules can be enhanced up to 10 times by using a 3 µm diameter latex sphere while adding almost no photoluminescence background. We report a full characterization of the two-photon fluorescence enhancement by a single microsphere using fluorescence correlation spectroscopy. This opens new routes to enhance non-linear optical signals and extend biophotonic applications. PMID:21258531

  13. Highly fluorescent BF2 complexes of hydrazine-Schiff base linked bispyrrole.

    PubMed

    Yu, Changjiang; Jiao, Lijuan; Zhang, Ping; Feng, Zeya; Cheng, Chi; Wei, Yun; Mu, Xiaolong; Hao, Erhong

    2014-06-06

    A series of BF2 complexes of hydrazine-Schiff base linked bispyrrole have been prepared from a simple two-step reaction from commercially available substances and are highly fluorescent in solution, film, and solid states with larger Stokes shift and excellent photostabilities comparable or even super to those of their BODIPY analogues. These resultant fluorescent dyes are highly susceptible to the postfunctionalization, as demonstrated in this work via the Knoevenagel condensation to introducing functionalities or tether groups to the chromophore.

  14. A High-Speed Detector System for X-ray Fluorescence Microprobes.

    SciTech Connect

    Siddons,P.D.; Dragone, A.; De Geronimo, g.; Kuczewski, A.; Kuczewski, J.; O

    2006-10-29

    We have developed a high-speed system for collecting x-ray fluorescence microprobe data, based on ASICs developed at BNL and high-speed processors developed by CSIRO. The system can collect fluorescence data in a continuous raster scan mode, and present elemental images in real time using Ryan's Dynamic Analysis algorithm. We will present results from a 32-element prototype array illustrating the concept. The final instrument will have 384 elements arranged in a square array around a central hole.

  15. Highly thymine-dependent formation of fluorescent copper nanoparticles templated by ss-DNA

    NASA Astrophysics Data System (ADS)

    Liu, Guiying; Shao, Yong; Peng, Jian; Dai, Wei; Liu, Lingling; Xu, Shujuan; Wu, Fei; Wu, Xiaohua

    2013-08-01

    Double-stranded DNAs (ds-DNAs) have been identified as efficient templates favoring the formation of fluorescent copper nanoparticles (Cu NPs). Herein, we have tried to synthesize fluorescent Cu NPs using single-stranded DNAs (ss-DNAs) as templates and to identify the critical DNA sequences. By comparing the results using homopolymer DNAs, hairpin DNAs, and pristine ss-DNAs as templates, we found that DNA thymine base plays a dominant role in producing red-emissive fluorescent Cu NPs on ss-DNA templates. The thymine-dependent growth of the fluorescent Cu NPs is confirmed by Hg2+ mediated T-T base pair in comparison with the other non-specific metal ions, which could be developed into a practical sensor for turn-on fluorescence detection of Hg2+ with a high selectivity. The mechanism is briefly discussed according the DNA sequence-dependent formation of fluorescent Cu NPs. This work demonstrates the sequence role in producing fluorescent Cu NPs that could serve as promising fluorescent nanoprobes in biosensing and DNA-hosted Cu nanomaterials.

  16. Quantitative 3D Fluorescence Imaging of Single Catalytic Turnovers Reveals Spatiotemporal Gradients in Reactivity of Zeolite H-ZSM-5 Crystals upon Steaming.

    PubMed

    Ristanović, Zoran; Hofmann, Jan P; De Cremer, Gert; Kubarev, Alexey V; Rohnke, Marcus; Meirer, Florian; Hofkens, Johan; Roeffaers, Maarten B J; Weckhuysen, Bert M

    2015-05-27

    Optimizing the number, distribution, and accessibility of Brønsted acid sites in zeolite-based catalysts is of a paramount importance to further improve their catalytic performance. However, it remains challenging to measure real-time changes in reactivity of single zeolite catalyst particles by ensemble-averaging characterization methods. In this work, a detailed 3D single molecule, single turnover sensitive fluorescence microscopy study is presented to quantify the reactivity of Brønsted acid sites in zeolite H-ZSM-5 crystals upon steaming. This approach, in combination with the oligomerization of furfuryl alcohol as a probe reaction, allowed the stochastic behavior of single catalytic turnovers and temporally resolved turnover frequencies of zeolite domains smaller than the diffraction limited resolution to be investigated with great precision. It was found that the single turnover kinetics of the parent zeolite crystal proceeds with significant spatial differences in turnover frequencies on the nanoscale and noncorrelated temporal fluctuations. Mild steaming of zeolite H-ZSM-5 crystals at 500 °C led to an enhanced surface reactivity, with up to 4 times higher local turnover rates than those of the parent H-ZSM-5 crystals, and revealed remarkable heterogeneities in surface reactivity. In strong contrast, severe steaming at 700 °C significantly dealuminated the zeolite H-ZSM-5 material, leading to a 460 times lower turnover rate. The differences in measured turnover activities are explained by changes in the 3D aluminum distribution due to migration of extraframework Al-species and their subsequent effect on pore accessibility, as corroborated by time-of-flight secondary ion mass spectrometry (TOF-SIMS) sputter depth profiling data.

  17. Quantitative 3D Fluorescence Imaging of Single Catalytic Turnovers Reveals Spatiotemporal Gradients in Reactivity of Zeolite H-ZSM-5 Crystals upon Steaming

    PubMed Central

    2015-01-01

    Optimizing the number, distribution, and accessibility of Brønsted acid sites in zeolite-based catalysts is of a paramount importance to further improve their catalytic performance. However, it remains challenging to measure real-time changes in reactivity of single zeolite catalyst particles by ensemble-averaging characterization methods. In this work, a detailed 3D single molecule, single turnover sensitive fluorescence microscopy study is presented to quantify the reactivity of Brønsted acid sites in zeolite H-ZSM-5 crystals upon steaming. This approach, in combination with the oligomerization of furfuryl alcohol as a probe reaction, allowed the stochastic behavior of single catalytic turnovers and temporally resolved turnover frequencies of zeolite domains smaller than the diffraction limited resolution to be investigated with great precision. It was found that the single turnover kinetics of the parent zeolite crystal proceeds with significant spatial differences in turnover frequencies on the nanoscale and noncorrelated temporal fluctuations. Mild steaming of zeolite H-ZSM-5 crystals at 500 °C led to an enhanced surface reactivity, with up to 4 times higher local turnover rates than those of the parent H-ZSM-5 crystals, and revealed remarkable heterogeneities in surface reactivity. In strong contrast, severe steaming at 700 °C significantly dealuminated the zeolite H-ZSM-5 material, leading to a 460 times lower turnover rate. The differences in measured turnover activities are explained by changes in the 3D aluminum distribution due to migration of extraframework Al-species and their subsequent effect on pore accessibility, as corroborated by time-of-flight secondary ion mass spectrometry (TOF-SIMS) sputter depth profiling data. PMID:25867455

  18. Development of chiral metal amides as highly reactive catalysts for asymmetric [3 + 2] cycloadditions

    PubMed Central

    Yamashita, Yasuhiro; Yoshimoto, Susumu; Dutton, Mark J

    2016-01-01

    Summary Highly efficient catalytic asymmetric [3 + 2] cycloadditions using a chiral copper amide are reported. Compared with the chiral CuOTf/Et3N system, the CuHMDS system showed higher reactivity, and the desired reactions proceeded in high yields and high selectivities with catalyst loadings as low as 0.01 mol %. PMID:27559396

  19. Size Distribution and Fluorescent Characteristics of Colloidal CDOM: Indicators of the Provenance and Reactivity of CDOM in Coastal Waters?

    DTIC Science & Technology

    2002-09-30

    was isolated from conventionally-filtered seawater (< 0.2 µm) using cross flow filtration (CFF) (or ultrafiltration). Seawater samples were... emmission matrices (EEMS) plotted as an intensity contour surface. 3D fluorescence spectroscopy has been shown to be an effective means for...year we have explored the use of Flow Field-Flow Fractionation (Flow FFF) for separting the colloidal CDOM fraction from seawater. Unlike CFF, which

  20. Comparison of C-reactive protein and high-sensitivity C-reactive protein levels in patients on hemodialysis.

    PubMed

    Helal, Imed; Zerelli, Lilia; Krid, Madiha; ElYounsi, Fethi; Ben Maiz, Hedi; Zouari, Bechir; Adelmoula, Jaouida; Kheder, Adel

    2012-05-01

    Chronic inflammation is highly prevalent in patients on hemodialysis (HD), as evidenced by increased levels of C-reactive protein (CRP). We compared CRP to high-sensitivity C-reactive protein (hs-CRP) to determine whether it has any clinical implications and prognostic significance in terms of mortality. CRP was measured using a standard immunoturbidometric assay on the COBAS® INTEGRA system and hs-CRP was measured using the Dade Behring on the Konelab Nephelometer in 50 patients on HD. CRP (≥6 mg/L) and hs-CRP (≥3 mg/L) levels were elevated in 30% and 54% of the patients, respectively. A significant correlation was noted between hs-CRP and CRP levels (r = 0.98, P <0.001). Deming regression analysis showed that the slope was near one (r = 0.90; 0.83-0.94) and that the intercept was small. Multivariate regression confirmed that age above 40 years (RR = 3.69, P = 0.027) and duration on HD greater than five years (RR = 3.71, P = 0.028) remained significant independent predictors of serum hs-CRP. Thirteen patients died during follow-up (26%). Multivariate Cox regression demonstrated that hs-CRP (RR = 1.062, P = 0.03) and CRP levels (RR = 1.057, P = 0.009) and age (RR = 1.078, P = 0.001) were the most powerful predictors of mortality. The CRP standard assay presents a reasonable alternative to the hs-CRP assay in patients on HD. The advantages of the CRP standard assay are its online and real-time availability as well as lower costs, particularly in developing countries.

  1. A highly selective fluorescent probe based on Michael addition for fast detection of hydrogen sulfide.

    PubMed

    Gao, Baozhen; Cui, Lixia; Pan, Yong; Xue, Minjie; Zhu, Boyu; Zhang, Guomei; Zhang, Caihong; Shuang, Shaomin; Dong, Chuan

    2017-02-15

    A new 4-hydroxy-1,8-naphthalimide-based compound (probe 1) has been designed and synthesized. The colorimetric and fluorescent properties of probe 1 towards hydrogen sulfide (H2S) were investigated in detail. The results show that the probe 1 could selectively and sensitively recognize H2S rather than other reactive sulfur species. The reaction mechanism of this probe is an intramolecular cyclization caused by the Michael addition of H2S to give 4-hydroxy-1,8-naphthalimide. The intramolecular charge transfer of 4-hydroxy-1,8-naphthalimide is significant. Probe 1 quickly responded to H2S and showed a 75-fold fluorescence enhancement in 5min. Moreover, probe 1 could detect H2S quantitatively with a detection limit as low as 0.23μM.

  2. A highly selective fluorescent probe based on Michael addition for fast detection of hydrogen sulfide

    NASA Astrophysics Data System (ADS)

    Gao, Baozhen; Cui, Lixia; Pan, Yong; Xue, Minjie; Zhu, Boyu; Zhang, Guomei; Zhang, Caihong; Shuang, Shaomin; Dong, Chuan

    2017-02-01

    A new 4-hydroxy-1,8-naphthalimide-based compound (probe 1) has been designed and synthesized. The colorimetric and fluorescent properties of probe 1 towards hydrogen sulfide (H2S) were investigated in detail. The results show that the probe 1 could selectively and sensitively recognize H2S rather than other reactive sulfur species. The reaction mechanism of this probe is an intramolecular cyclization caused by the Michael addition of H2S to give 4-hydroxy-1,8-naphthalimide. The intramolecular charge transfer of 4-hydroxy-1,8-naphthalimide is significant. Probe 1 quickly responded to H2S and showed a 75-fold fluorescence enhancement in 5 min. Moreover, probe 1 could detect H2S quantitatively with a detection limit as low as 0.23 μM.

  3. A Sensitive Ratiometric Fluorescent Sensor for Zinc(II) with High Selectivity

    PubMed Central

    Lv, Yuanyuan; Cao, Mingda; Li, Jiakai; Wang, Junbo

    2013-01-01

    A new fluorescent Zn2+ chemosensor (P1) based on a functionalized porphyrin was synthesized and characterized. P1 displayed dramatic ratiometric variations in absorption and fluorescent emission spectra upon exposure to Zn2+ due to the formation of a 1:1 Zn2+/P1 complex. The sensor also exhibited high selectivity and sensitivity toward Zn2+ over other common metal ions in the physiological pH range with a detection limit of 1.8 μM. The sensor showed fast response times and excellent reproducibility, thus confirming its potential applicability as a fluorescent sensor for Zn2+ sensing. PMID:23467028

  4. Activated Metal Oxide Surfaces as Highly Reactive Environments

    DTIC Science & Technology

    1990-08-03

    underway. " Synthesis of Ultra-High Surface Area Fe203 by Precipitation Methods Yong-Xi Li A series of precipitations of Fe(OH) 3 (from FeCl 3) at...Progress was also made on developing new aerogel procedures for synthesis of ultra-high surface area magnesium oxide. Finally,’ome metal oxide molecules...were studied in chemical reactions and by theoretical methods .-) Three students earned Ph.D. degrees and one an M.S. degree. A visiting professor and

  5. 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.

  6. Fluorescence imaging of reactive oxygen species by confocal laser scanning microscopy for track analysis of synchrotron X-ray photoelectric nanoradiator dose: X-ray pump-optical probe.

    PubMed

    Jeon, Jae Kun; Han, Sung Mi; Kim, Jong Ki

    2016-09-01

    Bursts of emissions of low-energy electrons, including interatomic Coulomb decay electrons and Auger electrons (0-1000 eV), as well as X-ray fluorescence produced by irradiation of large-Z element nanoparticles by either X-ray photons or high-energy ion beams, is referred to as the nanoradiator effect. In therapeutic applications, this effect can damage pathological tissues that selectively take up the nanoparticles. Herein, a new nanoradiator dosimetry method is presented that uses probes for reactive oxygen species (ROS) incorporated into three-dimensional gels, on which macrophages containing iron oxide nanoparticles (IONs) are attached. This method, together with site-specific irradiation of the intracellular nanoparticles from a microbeam of polychromatic synchrotron X-rays (5-14 keV), measures the range and distribution of OH radicals produced by X-ray emission or superoxide anions ({\\rm{O}}_2^-) produced by low-energy electrons. The measurements are based on confocal laser scanning of the fluorescence of the hydroxyl radical probe 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl] benzoic acid (APF) or the superoxide probe hydroethidine-dihydroethidium (DHE) that was oxidized by each ROS, enabling tracking of the radiation dose emitted by the nanoradiator. In the range 70 µm below the irradiated cell, ^\\bullet{\\rm{OH}} radicals derived mostly from either incident X-ray or X-ray fluorescence of ION nanoradiators are distributed along the line of depth direction in ROS gel. In contrast, {\\rm{O}}_2^- derived from secondary electron or low-energy electron emission by ION nanoradiators are scattered over the ROS gel. ROS fluorescence due to the ION nanoradiators was observed continuously to a depth of 1.5 mm for both oxidized APF and oxidized DHE with relatively large intensity compared with the fluorescence caused by the ROS produced solely by incident primary X-rays, which was limited to a depth of 600 µm, suggesting dose enhancement as well as more

  7. High-throughput screening assay of hepatitis C virus helicase inhibitors using fluorescence-quenching phenomenon

    SciTech Connect

    Tani, Hidenori; Akimitsu, Nobuyoshi; Fujita, Osamu; Matsuda, Yasuyoshi; Miyata, Ryo; Tsuneda, Satoshi; Igarashi, Masayuki; Sekiguchi, Yuji; Noda, Naohiro

    2009-02-20

    We have developed a novel high-throughput screening assay of hepatitis C virus (HCV) nonstructural protein 3 (NS3) helicase inhibitors using the fluorescence-quenching phenomenon via photoinduced electron transfer between fluorescent dyes and guanine bases. We prepared double-stranded DNA (dsDNA) with a 5'-fluorescent-dye (BODIPY FL)-labeled strand hybridized with a complementary strand, the 3'-end of which has guanine bases. When dsDNA is unwound by helicase, the dye emits fluorescence owing to its release from the guanine bases. Our results demonstrate that this assay is suitable for quantitative assay of HCV NS3 helicase activity and useful for high-throughput screening for inhibitors. Furthermore, we applied this assay to the screening for NS3 helicase inhibitors from cell extracts of microorganisms, and found several cell extracts containing potential inhibitors.

  8. Determination of ANA specificity using multiplexed fluorescent microsphere immunoassay in patients with ANA positivity at high titres after infliximab treatment: preliminary results.

    PubMed

    Caramaschi, Paola; Ruzzenente, Orazio; Pieropan, Sara; Volpe, Alessandro; Carletto, Antonio; Bambara, Lisa Maria; Biasi, Domenico

    2007-05-01

    To evaluate ANA specificity using the fully automated multiplexed fluorescent microsphere immunoassay in patients affected either by rheumatoid arthritis or ankylosing spondylitis who developed strong positivity for ANA as assessed by indirect immunofluorescent method on HEp-2 cells during infliximab treatment. Three men affected by ankylosing spondylitis and 12 women affected by rheumatoid arthritis who developed ANA positivity at high titres during infliximab treatment underwent the identification of ANA specificity by multiplexed fluorescent microsphere immunoassay; moreover anti-DNA and anti-ENA antibodies were tested by indirect immunofluorescence and ELISA method, respectively. In 4 out of 15 cases, the determination of ANA reactivity by multiplexed fluorescent microsphere immunoassay was also performed on the serum collected before infliximab administration. One patient affected by rheumatoid arthritis showed multiple ANA reactivities against SS-A, SS-B, RNP, Sm, Jo-1 and histones; one patient affected by ankylosing spondylitis resulted positive for the same autoantibodies, except for anti-Sm antibody. Moreover, two patients, one with rheumatoid arthritis and one with ankylosing spondylitis, showed single antibody specificity to SS-B and RNP, respectively. The remaining 11 cases did not show any positivity. Instead, all the patients resulted negative for anti-ENA antibodies by the ELISA method. In the four cases tested for ANA specificity by multiplexed fluorescent microsphere immunoassay before and after infliximab administration no difference was found. The search for anti-DNA antibody always resulted negative by both the traditional immunofluorescent assay and the novel technique. The use of multiplexed fluorescent microsphere immunoassay in patients treated with infliximab with ANA positivity at high titres allowed to find some ANA specificities which were not revealed by ELISA method. Nevertheless, the majority of patients resulted negative in spite of

  9. Molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin.

    PubMed

    Wang, Xiaoyan; Yu, Jialuo; Kang, Qi; Shen, Dazhong; Li, Jinhua; Chen, Lingxin

    2016-03-15

    A facile strategy was developed to prepare molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin (PC) based on fluorescence resonance energy transfer (FRET), via a sol-gel polymerization process using nitrobenzoxadiazole (NBD) as fluorescent signal source. The ratio of two fluorescence peak emission intensities of NBD and PC was utilized to determine the concentration of PC, which could effectively reduce the background interference and fluctuation of diverse conditions. As a result, this sensor obtained high sensitivity with a low detection limit of 0.14 nM within 6 min, and excellent recognition specificity for PC over its analogues with a high imprinting factor of 9.1. Furthermore, the sensor attained high recoveries in the range of 93.8-110.2% at three spiking levels of PC, with precisions below 4.7% in seawater and lake water samples. The developed sensor strategy demonstrated simplicity, reliability, rapidity, high selectivity and high sensitivity, proving to be a feasible way to develop high efficient fluorescence sensors and thus potentially applicable for ultratrace analysis of complicated matrices.

  10. The importance of narcissism in predicting proactive and reactive aggression in moderately to highly aggressive children.

    PubMed

    Barry, Tammy D; Thompson, Alice; Barry, Christopher T; Lochman, John E; Adler, Kristy; Hill, Kwoneathia

    2007-01-01

    The present study examined the importance of psychopathy-linked narcissism in predicting proactive and reactive aggression and conduct problems in a group of 160 moderately to highly aggressive children (mean age of 10 years, 9 months). Children's self-report of self-esteem and parent and teacher report of dimensions of psychopathy [narcissism, callous-unemotional (CU) traits, and impulsivity], proactive and reactive aggression, and conduct problems were collected. Composites of parent and teacher ratings of children's behavior were used. Consistent with the study's hypotheses, narcissism predicted unique variance in both proactive and reactive aggression, even when controlling for other dimensions of psychopathy, demographic variables associated with narcissism, and the alternative subtype of aggression. As hypothesized, impulsivity was significantly associated with only reactive aggression. CU traits were not related to proactive or reactive aggression once the control variables were entered. All dimensions of psychopathy predicted unique variance in conduct problems. Consistent with prediction, narcissism was not significantly related to general self-esteem, providing support that narcissism and self-esteem are different constructs. Furthermore, narcissism and self-esteem related differentially to proactive aggression, reactive aggression, and conduct problems. Furthermore, narcissism but not self-esteem accounted for unique variance in aggression and conduct problems. The importance of narcissism in the prediction of aggressive behaviors and clinical implications are discussed.

  11. Highly Selective Two-Photon Fluorescent Probe for Ratiometric Sensing and Imaging Cysteine in Mitochondria.

    PubMed

    Niu, Weifen; Guo, Lei; Li, Yinhui; Shuang, Shaomin; Dong, Chuan; Wong, Man Shing

    2016-02-02

    A novel ratiometric mitochondrial cysteine (Cys)-selective two-photon fluorescence probe has been developed on the basis of a merocyanine as the fluorophore and an acrylate moiety as the biothiol reaction site. The biocompatible and photostable acrylate-functionalized merocyanine probe shows not only a mitochondria-targeting property but also highly selective detection and monitoring of Cys over other biothiols such as homocysteine (Hcy) and glutathione (GSH) and hydrogen sulfide (H2S) in live cells. In addition, this probe exhibits ratiometric fluorescence emission characteristics (F518/F452), which are linearly proportional to Cys concentrations in the range of 0.5-40 μM. More importantly, the probe and its released fluorophore, merocyanine, exhibit strong two-photon excited fluorescence (TPEF) with two-photon action cross-section (Φσmax) of 65.2 GM at 740 nm and 72.6 GM at 760 nm in aqueous medium, respectively, which is highly desirable for high contrast and brightness ratiometric two-photon fluorescence imaging of the living samples. The probe has been successfully applied to ratiometrically image and detect mitochondrial Cys in live cells and intact tissues down to a depth of 150 μm by two-photon fluorescence microscopy. Thus, this ratiometric two-photon fluorescent probe is practically useful for an investigation of Cys in living biological systems.

  12. Fluorescence lifetime plate reader: resolution and precision meet high-throughput.

    PubMed

    Petersen, Karl J; Peterson, Kurt C; Muretta, Joseph M; Higgins, Sutton E; Gillispie, Gregory D; Thomas, David D

    2014-11-01

    We describe a nanosecond time-resolved fluorescence spectrometer that acquires fluorescence decay waveforms from each well of a 384-well microplate in 3 min with signal-to-noise exceeding 400 using direct waveform recording. The instrument combines high-energy pulsed laser sources (5-10 kHz repetition rate) with a photomultiplier and high-speed digitizer (1 GHz) to record a fluorescence decay waveform after each pulse. Waveforms acquired from rhodamine or 5-((2-aminoethyl)amino) naphthalene-1-sulfonic acid dyes in a 384-well plate gave lifetime measurements 5- to 25-fold more precise than the simultaneous intensity measurements. Lifetimes as short as 0.04 ns were acquired by interleaving with an effective sample rate of 5 GHz. Lifetime measurements resolved mixtures of single-exponential dyes with better than 1% accuracy. The fluorescence lifetime plate reader enables multiple-well fluorescence lifetime measurements with an acquisition time of 0.5 s per well, suitable for high-throughput fluorescence lifetime screening applications.

  13. Toward robust high resolution fluorescence tomography: a hybrid row-action edge preserving regularization

    NASA Astrophysics Data System (ADS)

    Behrooz, Ali; Zhou, Hao-Min; Eftekhar, Ali A.; Adibi, Ali

    2011-02-01

    Depth-resolved localization and quantification of fluorescence distribution in tissue, called Fluorescence Molecular Tomography (FMT), is highly ill-conditioned as depth information should be extracted from limited number of surface measurements. Inverse solvers resort to regularization algorithms that penalize Euclidean norm of the solution to overcome ill-posedness. While these regularization algorithms offer good accuracy, their smoothing effects result in continuous distributions which lack high-frequency edge-type features of the actual fluorescence distribution and hence limit the resolution offered by FMT. We propose an algorithm that penalizes the total variation (TV) norm of the solution to preserve sharp transitions and high-frequency components in the reconstructed fluorescence map while overcoming ill-posedness. The hybrid algorithm is composed of two levels: 1) An Algebraic Reconstruction Technique (ART), performed on FMT data for fast recovery of a smooth solution that serves as an initial guess for the iterative TV regularization, 2) A time marching TV regularization algorithm, inspired by the Rudin-Osher-Fatemi TV image restoration, performed on the initial guess to further enhance the resolution and accuracy of the reconstruction. The performance of the proposed method in resolving fluorescent tubes inserted in a liquid tissue phantom imaged by a non-contact CW trans-illumination FMT system is studied and compared to conventional regularization schemes. It is observed that the proposed method performs better in resolving fluorescence inclusions at higher depths.

  14. Highly confined, enhanced surface fluorescence imaging with two-dimensional silver nanoparticle sheets

    SciTech Connect

    Usukura, Eiji; Shinohara, Shuhei; Okamoto, Koichi; Tamada, Kaoru; Lim, Jaehoon; Char, Kookheon

    2014-03-24

    A method of obtaining highly confined, enhanced surface fluorescence imaging is proposed using two-dimensional (2D) silver nanoparticle (AgMy) sheets. This technique is based on the localized surface plasmon resonance excited homogeneously on a 2D silver nanoparticle sheet. The AgMy sheets are fabricated at the air–water interface by self-assembly and transferred onto hydrophobic glass substrates. These sheets can enhance the fluorescence only when the excitation wavelength overlaps with the plasmon resonance wavelength. To confirm the validity of this technique, two separate test experiments are performed. One is the epifluorescence microscope imaging of a quantum dot 2D sheet on the AgMy 2D sheet with a SiO{sub 2} spacer layer, where the fluorescence is maximized with the 20 nm SiO{sub 2} layer, determined by the Förster resonance energy transfer distances. The second experiment is the imaging of a single fluorescence bead with a total internal reflection fluorescent microscope. We confirmed that the AgMy sheet provides a 4-fold increase in fluorescence with a 160-nm spatial resolution at 30 ms/frame snapshot. The AgMy sheet will be a powerful tool for high sensitivity and high-resolution real time bioimaging at nanointerfaces.

  15. Premixed direct injection nozzle for highly reactive fuels

    DOEpatents

    Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin Paul; York, William David; Uhm, Jong Ho; Zuo, Baifang

    2013-09-24

    A fuel/air mixing tube for use in a fuel/air mixing tube bundle is provided. The fuel/air mixing tube includes an outer tube wall extending axially along a tube axis between an inlet end and an exit end, the outer tube wall having a thickness extending between an inner tube surface having a inner diameter and an outer tube surface having an outer tube diameter. The tube further includes at least one fuel injection hole having a fuel injection hole diameter extending through the outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

  16. Fluorescent boronate-based polymer nanoparticles with reactive oxygen species (ROS)-triggered cargo release for drug-delivery applications

    NASA Astrophysics Data System (ADS)

    Jäger, Eliézer; Höcherl, Anita; Janoušková, Olga; Jäger, Alessandro; Hrubý, Martin; Konefał, Rafał; Netopilik, Miloš; Pánek, Jiří; Šlouf, Miroslav; Ulbrich, Karel; Štěpánek, Petr

    2016-03-01

    A new drug-delivery system of polymer nanoparticles (NPs) bearing pinacol-type boronic ester and alkyne moieties displaying triggered self-immolative polymer degradation in the presence of reactive oxygen species (ROS) with the capability of cellular imaging is presented. The NPs specifically release their drug cargo under concentrations of ROS that are commonly found in the intracellular environment of certain tumors and of inflamed tissues and exhibit significant cytotoxicity to cancer cells compared to their non-ROS-responsive counterparts.A new drug-delivery system of polymer nanoparticles (NPs) bearing pinacol-type boronic ester and alkyne moieties displaying triggered self-immolative polymer degradation in the presence of reactive oxygen species (ROS) with the capability of cellular imaging is presented. The NPs specifically release their drug cargo under concentrations of ROS that are commonly found in the intracellular environment of certain tumors and of inflamed tissues and exhibit significant cytotoxicity to cancer cells compared to their non-ROS-responsive counterparts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00791k

  17. Impact reactivity of materials at very high oxygen pressure

    NASA Technical Reports Server (NTRS)

    Connor, H. W.; Minchey, J. G.; Crowder, R.; Davidson, R.

    1983-01-01

    The requirements for impact testing of materials in an oxygen atmosphere at pressures from 82.7 MPa (12,000 psi) to 172 MPa (25,000 psi) were evaluated. The impact tester system was evaluated for potential pressure increases from 69 MPa (10,000 psi) to 82.7 MPa (12,000 psi). The low pressure oxygen and nitrogen systems, the impact tower, the impact test cell, and the high pressure oxygen system were evaluated individually. Although the structural integrity of the impact test cell and the compressor were sufficient for operation at 82.7 MPa (12,000 psi), studies revealed possible material incompatibility at that pressure and above. It was recommended that if a component should be replaced for 82.7 MPa (12,000 psi) operation the replacement should meet the final objectives of 172 MPa (25,000 psi). Recommended changes in the system include; use of Monel 400 for pressures above 82.7 MPa (12,000 psi), use of bellows to replace the seal in the impact tester, use of a sapphire window attached to a fiber optic for event sensing, and use of a three diaphragm compressor.

  18. Protein-reactive, thermoresponsive copolymers with high flexibility and biodegradability.

    PubMed

    Guan, Jianjun; Hong, Yi; Ma, Zuwei; Wagner, William R

    2008-04-01

    A family of injectable, biodegradable, and thermosensitive copolymers based on N-isopropylacrylamide, acrylic acid, N-acryloxysuccinimide, and a macromer polylactide-hydroxyethyl methacrylate were synthesized by free radical polymerization. Copolymers were injectable at or below room temperature and formed robust hydrogels at 37 degrees C. The effects of monomer ratio, polylactide length, and AAc content on the chemical and physical properties of the hydrogel were investigated. Copolymers exhibited lower critical solution temperatures (LCSTs) from 18 to 26 degrees C. After complete hydrolysis, hydrogels were soluble in phosphate buffered saline at 37 degrees C with LCSTs above 40.8 degrees C. Incorporation of type I collagen at varying mass fractions by covalent reaction with the copolymer backbone slightly increased LCSTs. Water content was 32-80% without collagen and increased to 230% with collagen at 37 degrees C. Hydrogels were highly flexible and relatively strong at 37 degrees C, with tensile strengths from 0.3 to 1.1 MPa and elongations at break from 344 to 1841% depending on NIPAAm/HEMAPLA ratio, AAc content, and polylactide length. Increasing the collagen content decreased both elongation at break and tensile strength. Hydrogel weight loss at 37 degrees C was 85-96% over 21 days and varied with polylactide content. Hydrogel weight loss at 37 degrees C was 85-96% over 21 days and varied with polylactide content. Degradation products were shown to be noncytotoxic. Cell adhesion on the hydrogels was 30% of that for tissue culture polystyrene but increased to statistically approximate this control surface after collagen incorporation. These newly described thermoresponsive copolymers demonstrated attractive properties to serve as cell or pharmaceutical delivery vehicles for a variety of tissue engineering applications.

  19. Preparation and characterization of fluorescent microtubes with high length/diameter ratios

    NASA Astrophysics Data System (ADS)

    Chu, Maoquan; Huang, Jiasheng

    2009-02-01

    Fluorescent microtubes were prepared by self-assembly of CdTe quantum dots (QDs) following calcination at 500 °C using silkworm silks as templates. The obtained microtubes exhibited high length/diameter ratios. The cross-sectional dimension of the microtubes was no more than 10 µm, but the length could be up to several millimeters. The microtube wall was mainly composed of CdO, Cd3TeO6, and CdCO3 nanocrystals. Compared with the original red fluorescent CdTe QDs and the silk/QD core-shell structures, the microtubes exhibited a bright green-yellow fluorescence. The approach reported in this work opens the possibility of the large-scale preparation of fluorescent microtubes for both fundamental research and applications.

  20. Laser measurement of the spectral extinction coefficients of fluorescent, highly absorbing liquids. [crude petroleum oils

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.

    1982-01-01

    A conceptual method is developed to deduce rapidly the spectral extinction coefficient of fluorescent, highly absorbing liquids, such as crude or refined petroleum oils. The technique offers the advantage of only requiring one laser wavelength and a single experimental assembly and execution for any specific fluorescent liquid. The liquid is inserted into an extremely thin wedge-shaped cavity for stimulation by a laser from one side and flurescence measurement on the other side by a monochromator system. For each arbitrarily selected extinction wavelength, the wedge is driven slowly to increasing thicknesses until the fluorescence extinguishes. The fluorescence as a function of wedge thickness permits a determination of the extinction coefficient using an included theoretical model. When the monochromator is set to the laser emission wavelength, the extinction coefficient is determined using the usual on-wavelength signal extinction procedure.

  1. High-quality substrate for fluorescence enhancement using agarose-coated silica opal film.

    PubMed

    Xu, Ming; Li, Juan; Sun, Liguo; Zhao, Yuanjin; Xie, Zhuoying; Lv, Linli; Zhao, Xiangwei; Xiao, Pengfeng; Hu, Jing; Lv, Mei; Gu, Zhongze

    2010-08-01

    To improve the sensitivity of fluorescence detection in biochip, a new kind of substrates was developed by agarose coating on silica opal film. In this study, silica opal film was fabricated on glass substrate using the vertical deposition technique. It can provide stronger fluorescence signals and thus improve the detection sensitivity. After coating with agarose, the hybrid film could provide a 3D support for immobilizing sample. Comparing with agarose-coated glass substrate, the agarose-coated opal substrates could selectively enhance particular fluorescence signals with high sensitivity when the stop band of the silica opal film in the agarose-coated opal substrate overlapped the fluorescence emission wavelength. A DNA hybridization experiment demonstrated that fluorescence intensity of special type of agarose-coated opal substrates was about four times that of agarose-coated glass substrate. These results indicate that the optimized agarose-coated opal substrate can be used for improving the sensitivity of fluorescence detection with high quality and selectivity.

  2. Three dimensional microfluidics with embedded microball lenses for parallel and high throughput multicolor fluorescence detection

    PubMed Central

    Fan, Y. J.; Wu, Y. C.; Chen, Y.; Kung, Y. C.; Wu, T. H.; Huang, K. W.; Sheen, H. J.; Chiou, P. Y.

    2013-01-01

    We report a 3D microfluidic device with 32 detection channels and 64 sheath flow channels and embedded microball lens array for high throughput multicolor fluorescence detection. A throughput of 358 400 cells/s has been accomplished. This device is realized by utilizing solid immersion micro ball lens arrays for high sensitivity and parallel fluorescence detection. High refractive index micro ball lenses (n = 2.1) are embedded underneath PDMS channels close to cell detection zones in channels. This design permits patterning high N.A. micro ball lenses in a compact fashion for parallel fluorescence detection on a small footprint device. This device also utilizes 3D microfluidic fabrication to address fluid routing issues in two-dimensional parallel sheath focusing and allows simultaneous pumping of 32 sample channels and 64 sheath flow channels with only two inlets. PMID:24404054

  3. THE HIGH TEMPERATURE CHEMICAL REACTIVITY OF LI2O

    SciTech Connect

    Kessinger, G.; Missimer, D.

    2009-11-13

    ) It is likely that some or all of the past high temperature phase behavior and vaporization experiments involving Li{sub 2}O(s) at temperatures above 1250 C have actually involved Li{sub 2}O(l). If these past measurements were actually measurements performed on Li{sub 2}O(l) instead of the solid, the thermochemical data for phases and species in the Li-O system will require reevaluation.

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

    PubMed

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

    2016-11-01

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

  5. A fluorescence high throughput screening method for the detection of reactive electrophiles as potential skin sensitizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Skin sensitization is an important toxicological end-point in the risk assessment of chemical allergens. Because of the complexity of the biological mechanisms associated with skin sensitization integrated approaches combining different chemical, biological and in silico methods are recommended to r...

  6. EVALUATION OF FGD DRY INJECTION SORBENTS AND ADDITIVES - VOLUME 1 - DEVELOPMENT OF HIGH REACTIVITY SORBENTS

    EPA Science Inventory

    The report discusses recent work addressing lime enhancement by slurrying with siliceous materials and testing in a laboratory packed-bed reactor, as part of EPA's efforts to develop low cost, retrofit flue gas cleaning technology, including the development of highly reactive sor...

  7. Hybridization chain reaction amplification for highly sensitive fluorescence detection of DNA with dextran coated microarrays.

    PubMed

    Chao, Jie; Li, Zhenhua; Li, Jing; Peng, Hongzhen; Su, Shao; Li, Qian; Zhu, Changfeng; Zuo, Xiaolei; Song, Shiping; Wang, Lianhui; Wang, Lihua

    2016-07-15

    Microarrays of biomolecules hold great promise in the fields of genomics, proteomics, and clinical assays on account of their remarkably parallel and high-throughput assay capability. However, the fluorescence detection used in most conventional DNA microarrays is still limited by sensitivity. In this study, we have demonstrated a novel universal and highly sensitive platform for fluorescent detection of sequence specific DNA at the femtomolar level by combining dextran-coated microarrays with hybridization chain reaction (HCR) signal amplification. Three-dimensional dextran matrix was covalently coated on glass surface as the scaffold to immobilize DNA recognition probes to increase the surface binding capacity and accessibility. DNA nanowire tentacles were formed on the matrix surface for efficient signal amplification by capturing multiple fluorescent molecules in a highly ordered way. By quantifying microscopic fluorescent signals, the synergetic effects of dextran and HCR greatly improved sensitivity of DNA microarrays, with a detection limit of 10fM (1×10(5) molecules). This detection assay could recognize one-base mismatch with fluorescence signals dropped down to ~20%. This cost-effective microarray platform also worked well with samples in serum and thus shows great potential for clinical diagnosis.

  8. Preparation of highly fluorescent magnetic nanoparticles for analytes-enrichment and subsequent biodetection.

    PubMed

    Zhang, Bingbo; Chen, Bingdi; Wang, Yilong; Guo, Fangfang; Li, Zhuoquan; Shi, Donglu

    2011-01-15

    Bifunctional nanoparticles with highly fluorescence and decent magnetic properties have been widely used in biomedical application. In this study, highly fluorescent magnetic nanoparticles (FMNPs) with uniform size of ca. 40 nm are prepared by encapsulation of both magnetic nanoparticles (MNPs) and shell/core quantum dots (QDs) with well-designed shell structure/compositions into silica matrix via a one-pot reverse microemulsion approach. The spectral analysis shows that the FMNPs hold high fluorescent quantum yield (QY). The QYs and saturation magnetization of the FMNPs can be regulated by varying the ratio of the encapsulated QDs to MNPs. Moreover, the surface of the FMNPs can be modified to offer chemical groups for antibody conjugation for following use in target-enrichment and subsequent fluorescent detection. The in vitro immunofluorescence assay and flow cytometric analysis indicate that the bifunctional FMNPs-antibody bioconjugates are capable of target-enrichment, magnetic separation and can also be used as alternative fluorescent probes on flow cytometry for biodetection.

  9. Highly sensitive detection of superoxide dismutase based on an immunoassay with surface-enhanced fluorescence.

    PubMed

    Yang, Xiaoming; Dou, Yao; Zhu, Shanshan

    2013-06-07

    Herein, a novel highly sensitive enhanced-fluorescence immunoassay for detection of superoxide dismutase (SOD) is established by combining surface-enhanced fluorescence (SEF) with immuno-magnetic separation. Based on a sandwich-type immunoassay, analytes in samples are first captured by magnetic beads coated with a monoclonal antibody and then "sandwiched" by another monoclonal antibody on silver nanoparticles labeled with fluorescein-labeled oligonucleotides in the presence of a magnet. Subsequently, the immune complex is enriched by exposure to a magnetic field. Lastly, the fluorescence intensity is measured according to the number of dissociated fluoresceins. The increased fluorescence intensity permits highly sensitive detection of SOD in a linear range of 10-8 × 10(5) pg mL(-1), with a detection limit of 4 pg mL(-1) at a signal-to-noise ratio of 3. Significantly, this method was validated for detection of SOD in human serum, human urine, and cosmetic samples. Moreover, the reliability and accuracy of results obtained by the enhanced-fluorescence method was confirmed by the analysis of high performance liquid chromatography (HPLC).

  10. The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates

    NASA Astrophysics Data System (ADS)

    Shen, Yubin

    As one category of energetic materials, impact-initiated reactive materials are able to release a high amount of stored chemical energy under high strain rate impact loading, and are used extensively in civil and military applications. In general, polymers are introduced as binder materials to trap the reactive metal powders inside, and also act as an oxidizing agent for the metal ingredient. Since critical attention has been paid on the metal / metal reaction, only a few types of polymer / reactive metal interactions have been studied in the literature. With the higher requirement of materials resistant to different thermal and mechanical environments, the understanding and characterization of polymer / reactive metal interactions are in great demand. In this study, PTFE (Polytetrafluoroethylene) 7A / Ti (Titanium) composites were studied under high strain rates by utilizing the Taylor impact and SHPB tests. Taylor impact tests with different impact velocities, sample dimensions and sample configurations were conducted on the composite, equipped with a high-speed camera for tracking transient images during the sudden process. SHPB and Instron tests were carried out to obtain the stress vs. strain curves of the composite under a wide range of strain rates, the result of which were also utilized for fitting the constitutive relations of the composite based on the modified Johnson-Cook strength model. Thermal analyses by DTA tests under different flow rates accompanied with XRD identification were conducted to study the reaction mechanism between PTFE 7A and Ti when only heat was provided. Numerical simulations on Taylor impact tests and microstructural deformations were also performed to validate the constitutive model built for the composite system, and to investigate the possible reaction mechanism between two components. The results obtained from the high strain rate tests, thermal analyses and numerical simulations were combined to provide a systematic study on

  11. Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells

    NASA Astrophysics Data System (ADS)

    Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

    2016-06-01

    A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

  12. Life of fluorescent lamps operated at high frequencies with solid-state ballasts

    NASA Astrophysics Data System (ADS)

    Verderber, R. R.; Morse, O.; Rubinstein, F. M.

    1985-07-01

    Standard 40-watt, F-40, rapid-start, fluorescent lamps were operated with solid-state ballasts following the standard life-testing cycle of 3 hours on and 20 minutes off for more than 20,000 hours at high frequency. Lamp operating characteristics (starting voltage, filament voltage, arc current, and current-crest factor) were studied as factors affecting lamp life. Measurements show that fluorescent lamps can attain rated life at high frequency using solid-state ballasts. When lamps are operated in the dimmed mode, full filament power is required to sustain lamplife. The rate of lamp lumen depreciation is dependent on the lamp loading and not the operating frequency.

  13. Highly sensitive fluorescence detection of avidin/streptavidin with an optical interference mirror slide.

    PubMed

    Yasuda, Mitsuru; Akimoto, Takuo

    2012-01-01

    This paper presents highly sensitive fluorescence detections of avidin and streptavidin using an optical interference mirror (OIM) slide consisting of a plane mirror covered with an optical interference layer. Compared with a common glass slide, the OIM slide can enhance the fluorescence from a dye by more than 100-fold. We fabricated an OIM slide by depositing an optical interference layer of Al(2)O(3) on an Ag mirror. To enhance the fluorescence maximally, the optimal thickness of the Al(2)O(3) layer was estimated from optical interference theory. For detections of protein, avidin/streptavidin labeled with fluorescein, Cy3, and Cy5 were detected with biotin immobilized on an OIM slide with the optimal Al(2)O(3) thickness. We achieved a sensitivity improvement of more than 50-fold, comparing with a glass slide. Such a high degree of improvement would be a significant contribution to further progress in biomedical research and medical diagnostics.

  14. Translational diffusion of probe molecules under high pressure: A study by fluorescence recovery after photobleaching technique

    NASA Astrophysics Data System (ADS)

    Bonetti, Marco; Roger, Michel

    2013-02-01

    We present fluorescence recovery measurements after photobleaching performed under high pressure in liquids that fill square-section fused silica micro-capillaries. These micro-capillaries withstand pressure up to 2500 bar for a wall thickness of about 140 μm and fit easily on the microscope stage. This technique allows the translational diffusion coefficient of fluorescent molecules in liquids to be measured as a function of pressure. When the liquid sample is far from its glass transition the translational diffusive coefficient is in agreement with the Stokes-Einstein equation. As the glass transition is approached by further increasing the pressure, decoupling of the measured diffusion coefficient from the Stokes-Einstein relation is observed. These are the first measurements that combine the fluorescence recovery technique and high hydrostatic pressures. This experimental setup can also be used either with diamond or sapphire anvil cells in order to span a larger pressure range.

  15. High-resolution fluorescence microscopy to study transendothelial migration.

    PubMed

    Carman, Christopher V

    2012-01-01

    Immune system functions rely heavily on the ability of immune cells (i.e., blood leukocyte) to traffic throughout the body as they conduct immune surveillance and respond to pathogens. A monolayer of vascular endothelial cells (i.e., the "endothelium") provides a critical, selectively permeable barrier between two principal compartments of the body: the blood circulation and the tissue. Thus, knowledge of the basic mechanisms by which leukocytes migrate across the endothelium (i.e., undergo "transendothelial migration"; TEM) is critical for understanding immune system function. Cultured endothelial cell monolayers, used in combination with isolated blood leukocytes, provide a basis for highly useful in vitro models for study of TEM. When used in conjunction with high spatial and temporal resolution imaging approaches, such models have begun to reveal complex and dynamic cell behaviors in leukocytes and endothelial cells that ultimately determine TEM efficiency. In this chapter, we provide protocols for setting up a basic in vitro TEM system and for conducting high-resolution dynamic live-cell and three-dimensional fixed-cell imaging of TEM.

  16. Highly selective and sensitive fluorescent paper sensor for nitroaromatic explosive detection.

    PubMed

    Ma, Yingxin; Li, Hao; Peng, Shan; Wang, Leyu

    2012-10-02

    Rapid, sensitive, and selective detection of explosives such as 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP), especially using a facile paper sensor, is in high demand for homeland security and public safety. Although many strategies have been successfully developed for the detection of TNT, it is not easy to differentiate the influence from TNP. Also, few methods were demonstrated for the selective detection of TNP. In this work, via a facile and versatile method, 8-hydroxyquinoline aluminum (Alq(3))-based bluish green fluorescent composite nanospheres were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These polymer-coated nanocomposites are not only water-stable but also highly luminescent. Based on the dramatic and selective fluorescence quenching of the nanocomposites via adding TNP into the aqueous solution, a sensitive and robust platform was developed for visual detection of TNP in the mixture of nitroaromatics including TNT, 2,4-dinitrotoluene (DNT), and nitrobenzene (NB). Meanwhile, the fluorescence intensity is proportional to the concentration of TNP in the range of 0.05-7.0 μg/mL with the 3σ limit of detection of 32.3 ng/mL. By handwriting or finger printing with TNP solution as ink on the filter paper soaked with the fluorescent nanocomposites, the bluish green fluorescence was instantly and dramatically quenched and the dark patterns were left on the paper. Therefore, a convenient and rapid paper sensor for TNP-selective detection was fabricated.

  17. Phosphor blends for high-CRI fluorescent lamps

    DOEpatents

    Setlur, Anant Achyut; Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan; Beers, William Winder; Toth, Katalin; Balazs, Laszlo D.

    2008-06-24

    A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

  18. Antidepressant treatment differentially affects the phenotype of high and low stress reactive mice.

    PubMed

    Surget, Alexandre; Van Nieuwenhuijzen, Petra S; Heinzmann, Jan-Michael; Knapman, Alana; McIlwrick, Silja; Westphal, Willy-Paul; Touma, Chadi; Belzung, Catherine

    2016-11-01

    Modelling key endophenotypes can be a powerful approach to gain insight into mechanisms underlying the aetiology and pathophysiology of neuropsychiatric disorders. Based on evidence of stress hormone system dysregulations in depression, the Stress Reactivity (SR) mouse model has been generated by a selective breeding approach for extremes in HPA axis reactivity, resulting in high (HR), intermediate (IR) and low (LR) reactive mice. The characterisation of their phenotypic alterations has highlighted many similarities of HR and LR mice with the melancholic and atypical depression, respectively. We therefore aimed to examine whether the antidepressant fluoxetine (10 mg/kg/day i.p., 4-5 weeks) can ameliorate the phenotypic characteristics of HR and LR mice in neuroendocrine functions (HPA axis basal activity, stress reactivity, negative feedback), emotional reactivity/coping-strategy (open field, forced swim tests), spatial learning/memory (Morris water-maze) and hippocampal neurogenesis. Line differences in HPA axis reactivity were maintained under fluoxetine treatment. However, we observed fluoxetine effects on glucocorticoid-induced negative feedback, stress-coping behaviours, cognitive functions and neurogenesis. Specifically, our results revealed line-dependent consequences of fluoxetine treatment: (1) an amelioration of the 'melancholic-like' features of HR mice (reversing the negative feedback resistance, the hyperactive coping style and the memory deficits; increasing hippocampal neurogenesis); (2) an exacerbation of the phenotypic deviations of LR mice (increasing their pronounced negative feedback and passive coping style). Thus, these findings support the predictive validity of antidepressant treatment in the HR mouse line and emphasize the translational value of the SR mouse model for the development of therapeutic strategies based on endophenotype-driven classifications.

  19. High-yield reactivation of anionic tobacco peroxidase overexpressed in Escherichia coli.

    PubMed

    Zakharova, G S; Poloznikov, A A; Chubar, T A; Gazaryan, I G; Tishkov, V I

    2015-09-01

    Anionic tobacco peroxidase (TOP) is extremely active in chemiluminescence reaction of luminol oxidation without addition of enhancers and more stable than horseradish peroxidase under antibody conjugation conditions. In addition, recombinant TOP (rTOP) produced in Escherichia coli is known to be a perfect direct electron transfer catalyst on electrodes of various origin. These features make the task of development of a high-yield reactivation protocol for rTOP practically important. Previous attempts to reactivate the enzyme from E. coli inclusion bodies were successful, but the reported reactivation yield was only 14%. In this work, we thoroughly screened the refolding conditions for dilution protocol and compared it with gel-filtration chromatography. The impressive reactivation yield in the dilution protocol (85%) was achieved for 8 μg/mL solubilized rTOP protein and the refolding medium containing 0.3 mM oxidized glutathione, 0.05 mM dithiothreitol, 5 mM CaCl2, 5% glycerol in 50 mM Tris-HCl buffer, pH 9.6, with 1 μM hemin added at the 24th hour of incubation. A practically important discovery was a 30-40% increase in the reactivation yield upon delayed addition of hemin. The reactivation yield achieved is one of the highest reported in the literature on protein refolding by dilution. The final yield of purified active non-glycosylated rTOP was ca. 60 mg per L of E. coli culture, close to the yield reported before for tomato and tobacco plants overexpressing glycosylated TOP (60 mg/kg biomass) and much higher than for the previously reported refolding protocol (2.6 mg per L of E. coli culture).

  20. Formation and reactivity of surface-bound high oxidation state Ruthenium-oxo complexes.

    SciTech Connect

    Hornstein, B. J.; Dattelbaum, D. M.; Schoonover, J. R.; Meyer, T. J.

    2004-01-01

    Ruthenium polypyridyl oxalate complexes are precursors to high oxidation state species that can catalyze the oxidation of a variety of substrates. Covalent attachment of these reactive species to surfaces such at ZrO{sub 2} or TiO{sub 2} inhibit catalyst deactivation and provide supports from which to build electrocatalytic and photoelectrocatalytic devices. Unfortunately, few details of the effects of surface binding on reactivity are available in the literature. To this end, precursors such as, Ru(H{sub 2}O{sub 3}Ptpy)(C{sub 2}O{sub 4})(H{sub 2}O) and (C{sub 2}O{sub 4})(H{sub 2}O{sub 3}Ptpy)Ru-O-Ru(H{sub 2}O{sub 3}Ptpy)(C{sub 2}O{sub 4}) (tpy is terpyridine) have been synthesized and attached to TiO{sub 2}. Quantitative surface binding studies were carried out and acid catalyzed solvolysis was used to form the aqua species. The complexes were oxidized with Ce(IV) to their high-valent analogs and their reactivity toward selected substrates was tested. These studies not only provide information about the effects of surface binding on the reactivity of metal oxides but also have implications for the development of light-driven catalysts.

  1. Reactive power planning under high penetration of wind energy using Benders decomposition

    SciTech Connect

    Xu, Yan; Wei, Yanli; Fang, Xin; Li, Fangxing; Azim, Riyasat

    2015-11-05

    This study addresses the optimal allocation of reactive power volt-ampere reactive (VAR) sources under the paradigm of high penetration of wind energy. Reactive power planning (RPP) in this particular condition involves a high level of uncertainty because of wind power characteristic. To properly model wind generation uncertainty, a multi-scenario framework optimal power flow that considers the voltage stability constraint under the worst wind scenario and transmission N 1 contingency is developed. The objective of RPP in this study is to minimise the total cost including the VAR investment cost and the expected generation cost. Therefore RPP under this condition is modelled as a two-stage stochastic programming problem to optimise the VAR location and size in one stage, then to minimise the fuel cost in the other stage, and eventually, to find the global optimal RPP results iteratively. Benders decomposition is used to solve this model with an upper level problem (master problem) for VAR allocation optimisation and a lower problem (sub-problem) for generation cost minimisation. Impact of the potential reactive power support from doubly-fed induction generator (DFIG) is also analysed. Lastly, case studies on the IEEE 14-bus and 118-bus systems are provided to verify the proposed method.

  2. Reactive power planning under high penetration of wind energy using Benders decomposition

    DOE PAGES

    Xu, Yan; Wei, Yanli; Fang, Xin; ...

    2015-11-05

    This study addresses the optimal allocation of reactive power volt-ampere reactive (VAR) sources under the paradigm of high penetration of wind energy. Reactive power planning (RPP) in this particular condition involves a high level of uncertainty because of wind power characteristic. To properly model wind generation uncertainty, a multi-scenario framework optimal power flow that considers the voltage stability constraint under the worst wind scenario and transmission N 1 contingency is developed. The objective of RPP in this study is to minimise the total cost including the VAR investment cost and the expected generation cost. Therefore RPP under this condition ismore » modelled as a two-stage stochastic programming problem to optimise the VAR location and size in one stage, then to minimise the fuel cost in the other stage, and eventually, to find the global optimal RPP results iteratively. Benders decomposition is used to solve this model with an upper level problem (master problem) for VAR allocation optimisation and a lower problem (sub-problem) for generation cost minimisation. Impact of the potential reactive power support from doubly-fed induction generator (DFIG) is also analysed. Lastly, case studies on the IEEE 14-bus and 118-bus systems are provided to verify the proposed method.« less

  3. Linear ruby scale and one megabar. [high pressure fluorescence

    NASA Technical Reports Server (NTRS)

    Ruoff, A. L.

    1979-01-01

    The accuracy and validity of certain techniques used in studying high-pressure transitions have been investigated. Experiments which place upper limits of about 20 GPa and about 50 GPa on pressures practically attainable using uniaxial supported opposed anvil devices with tungsten carbide pistons and uniaxial opposed flat anvil diamond devices, respectively, are reported. Direct static determinations of the transition pressures of GaP by two different methods are described. The values obtained indicate that the linear ruby scale increasingly overestimates the transition pressure as the pressure rises above 10 GPa. It is further shown that the use of shock-based marker materials, such as silver, as the basis of pressure measurement in X-ray diffraction studies leads to bulk moduli of cubic carbides which are in extreme disagreement with expected values.

  4. High microvascular endothelial water permeability in mouse lung measured by a pleural surface fluorescence method.

    PubMed Central

    Carter, E P; Olveczky, B P; Matthay, M A; Verkman, A S

    1998-01-01

    Transport of water between the capillary and airspace compartments in lung encounters serial barriers: the alveolar epithelium, interstitium, and capillary endothelium. We previously reported a pleural surface fluorescence method to measure net capillary-to-airspace water transport. To measure the osmotic water permeability across the microvascular endothelial barrier in intact lung, the airspace was filled with a water-immiscible fluorocarbon. The capillaries were perfused via the pulmonary artery with solutions of specified osmolalites containing a high-molecular-weight fluorescent dextran. An increase in perfusate osmolality produced a prompt decrease in surface fluorescence due to dye dilution in the capillaries, followed by a slower return to initial fluorescence as capillary and lung interstitial osmolality equilibrate. A mathematical model was developed to determine the osmotic water permeability coefficient (Pf) of lung microvessels from the time course of pleural surface fluorescence. As predicted, the magnitude of the prompt change in surface fluorescence increased with decreased pulmonary artery perfusion rate and increased osmotic gradient size. With raffinose used to induce the osmotic gradient, Pf was 0.03 cm/s at 23 degrees C and was reduced 54% by 0.5 mM HgCl2. Temperature dependence measurements gave an Arrhenius activation energy (Ea) of 5.4 kcal/mol (12-37 degrees C). The apparent Pf induced by the smaller osmolytes mannitol and glycine was 0.021 and 0.011 cm/s (23 degrees C). Immunoblot analysis showed approximately 1.4 x 10(12) aquaporin-1 water channels/cm2 of capillary surface, which accounted quantitatively for the high Pf. These results establish a novel method for measuring osmotically driven water permeability across microvessels in intact lung. The high Pf, low Ea, and mercurial inhibition indicate the involvement of molecular water channels in water transport across the lung endothelium. PMID:9545071

  5. Multiplex and high-throughput DNA detection using surface plasmon mediated fluorescence

    NASA Astrophysics Data System (ADS)

    Mei, Zhong

    The overall objective of this research project was to develop a user-friendly and sensitive biosensor for nucleic acid aptamers with multiplexing and high-throughput capability. The sensing was based on the fluorescence signals emitted by the fluorophores coupling with plamonic nanoparticle (gold nanorod) deposited on a patterned substrate. Gold nanorods (GNRs) were synthesized using a binary mixture of hexadecyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL) in seed mediated growth method. Polytetrafluoroethylene (PTFE) printed glass slides were selectively coated with a gold thin-film to define hydrophilic areas for GNR deposition. Due to the wettablity contrast, GNR solution dropped on the slide was induced to assemble exclusively in the hydrophilic spots. By controlling temperature and humidity of the evaporation process, vertically-standing GNR arrays were achieved on the pattered slide. Fluorescence was conjugated to GNR surface via DNA double strand with tunable length. Theoretical simulation predicted a flat layer ( 30 nm thick) of uniform "hot spots" presented on the GNR tips, which could modify the nearby fluorescence. Experimentally, the vertical GNR arrays yielded metallic enhanced fluorescence (MEF) effect, which was dependent on the spectrum overlap and GNR-fluorophore distance. Specifically, the maximum enhancement of Quasar 670 and Alexa 750 was observed when it was coupled with GNR664 (plasmonic wavelength 664 nm) and GNR778 respectively at a distance of 16 nm, while the carboxyfluorescein (FAM) was at maximal intensity when attached to gold nanosphere520. This offers an opportunity for multiplexed DNA sensing. Based on this, we developed a novel GNR mediated fluorescence biosensor for DNA detection. Fluorescence labeled haipin-DNA probes were introduced to designated spots of GNR array with the matching LSPR wavelengths on the substrate. The fluorescence was quenched originally because of Forster resonance energy transfer (FRET) effect

  6. Micromixing visualization and quantification in a microscale multi-inlet vortex nanoprecipitation reactor using confocal-based reactive micro laser-induced fluorescence

    PubMed Central

    Shi, Yanxiang; Fox, Rodney O.; Olsen, Michael G.

    2014-01-01

    A technique for visualizing and quantifying reactive mixing for laminar and turbulent flow in a microscale chemical reactor using confocal-based microscopic laser induced fluorescence (confocal μ-LIF) was demonstrated in a microscale multi-inlet vortex nanoprecipitation reactor. Unlike passive scalar μ-LIF, the reactive μ-LIF technique is able to visualize and quantify micromixing effects. The confocal imaging results indicated that the flow in the reactor was laminar and steady for inlet Reynolds numbers of 10, 53, and 93. Mixing and reaction were incomplete at each of these Reynolds numbers. The results also suggested that although mixing by diffusion was enhanced near the midplane of the reactor at Rej = 53 and 93 due to very thin bands of acidic and basic fluid forming as the fluid spiraled towards the center of the reactor, near the top, and bottom walls of the reactor, the lower velocities due to fluid friction with the walls hindered the formation of these thin bands, and, thus, resulted in large regions of unmixed and unreacted fluid. At Rej = 240, the flow was turbulent and unsteady. The mixing and reaction processes were still found to be incomplete even at this highest Reynolds number. At the reactor midplane, the flow images at Rej = 240 showed unmixed base fluid near the center of the reactor, suggesting that just as in the Rej = 53 and 93 cases, lower velocities near the top and bottom walls of the reactor hinder the mixing and rection of the acidic and basic streams. Ensemble averages of line-scan profiles for the Rej = 240 were then calculated to provide statistical quantification of the microscale mixing in the reactor. These results further demonstrate that even at this highest Reynolds number investigated, mixing and reaction are incomplete. Visualization and quantification of micromixing using this reactive μ-LIF technique can prove useful in the validation of computational fluid dynamics models of micromixing within

  7. Rigid and high NA multiphoton fluorescence GRIN-endoscopes

    NASA Astrophysics Data System (ADS)

    Schenkl, Selma; Ehlers, Alexander; Le Harzic, Ronan; Stark, Martin; Riemann, Iris; Messerschmidt, Bernhard; Kaatz, Martin; König, Karsten

    2007-07-01

    Multiphoton autofluorescence imaging offers minimal-invasive examination of cells without the need of staining and complicated confocal detection systems. Therefore, it is especially interesting for non-invasive clinical diagnostics. To extend this sophisticated technique from superficial regions to deep lying cell layers, internal body parts and specimens difficult of access, the bulky optics need to be reduced in diameter. This is done by tiny GRIN-optics, based on a radial gradient in the reflective index. Of especial interest for multi-photon applications is the newly developed GRIN-lens assembly with increased numerical aperture. High resolution images of plant tissue, hair and cells show the improved image quality,compared to classical GRIN-lenses. The rigid GRIN-endoscopes are already applied in wound healing studies. Here, the GRIN-lenses with diameters smaller than 3 mm enter small skin depressions. They reproduce the focus of a conventional laser scanning tomograph tens of mm apart in the specimen under study. We present first clinical measurements of elastin and SHG of collagen of in-vivo human skin of venous ulcers (ulcer curis).

  8. Highly fluorescent rigid supramolecular polymeric nanowires constructed through multiple hydrogen bonds.

    PubMed

    Luo, Jia; Lei, Ting; Wang, Lei; Ma, Yuguo; Cao, Yong; Wang, Jian; Pei, Jian

    2009-02-18

    Supramolecular polymeric nanowires 1(n) constructed by a 3D shape-persistent hexaacid 1 through multiple hydrogen bonding interactions was developed. Single molecular nanoires were also obtained from its highly dilute solution.Hexaacid 1 containing pi-conjugated chromophores successfully self-assembled to afford these nanofibers with high solid quantum efficiency (22%), which provides us a pathway to fabricate optoelectronic devices using these highly fluorescent nanofibers.

  9. Rewritable multicolor fluorescent patterns for multistate memory devices with high data storage capacity.

    PubMed

    Lu, Zhisong; Liu, Yingshuai; Hu, Weihua; Lou, Xiong Wen David; Li, Chang Ming

    2011-09-14

    We report a branched polyethyleneimine (BPEI)-quantum dot (QD) based rewritable fluorescent system with a multicolor recording mode, in which BPEI is both QD-multicolor patterning "writer" and data erasing "remover". This method could write distinct colors from size-tailored QDs to represent large numbers of logic states for high data storage capacity.

  10. Radiochemical Analysis by High Sensitivity Micro X-Ray Fluorescence Detection

    SciTech Connect

    Ning Gao

    2006-05-12

    The primary objective of the project was to develop a novel dual-optic x-ray fluorescence instrument capable of doing radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford Site.

  11. High-throughput fluorescence assay of cytochrome P450 3A4

    PubMed Central

    Cheng, Qian; Sohl, Christal D; Guengerich, F Peter

    2013-01-01

    Cytochrome P450 mono-oxygenases (P450s) are the principal enzymes involved in the oxidative metabolism of drugs and other xenobiotics. In this protocol, we describe a fluorescence-based, high-throughput assay for measuring the activity of P450 3A4, one of the key enzymes involved in drug metabolism. The assay involves the oxidative debenzylation of a substituted coumarin, yielding an increase in fluorescence on reaction. The entire procedure can be accomplished in 1 h or less. PMID:19661996

  12. Resonance fluorescence of a cold atom in a high-finesse resonator

    SciTech Connect

    Bienert, Marc; Torres, J. Mauricio; Zippilli, Stefano; Morigi, Giovanna

    2007-07-15

    We study the spectra of emission of a system composed by an atom, tightly confined inside a high-finesse resonator, when the atom is driven by a laser and is at steady state of the cooling dynamics induced by laser and cavity fields. In general, the spectrum of resonance fluorescence and the spectrum at the cavity output contain complementary information about the dynamics undergone by the system. In certain parameter regimes, quantum interference effects between the scattering processes induced by cavity and laser fields lead to the selective suppression of features of the resonance fluorescence spectrum, which are otherwise visible in the spectrum of laser-cooled atoms in free space.

  13. ZnO Nanorod Array Grown on Ag Layer: A Highly Efficient Fluorescence Enhancement Platform

    PubMed Central

    Yin, Yongqi; Sun, Ye; Yu, Miao; Liu, Xiao; Jiang, Tingting; Yang, Bin; Liu, Danqing; Liu, Shaoqin; Cao, Wenwu

    2015-01-01

    ZnO nanorods (NRs) are known for ultra-sensitive biomolecule detection through fluorescence enhancement. In this work, we demonstrate that ZnO NR arrays grown on Ag layers can significantly improve the enhancement up to 86 times compared to that grown on bare Si, and the enhancement can be modified in a controlled manner by varying Ag thickness. The much improved waveguide properties are attributed to the high reflectance of the Ag layers and their tuning effect on the diameters of ZnO NRs. Our results provide a deep insight into the mechanism of NRs-based fluorescence enhancement platform. PMID:25633246

  14. 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.

  15. A Novel Fluorescent Probe for the Highly Selective and Sensitive Detection of Palladium in Aqueous Medium.

    PubMed

    Ma, Zhiwei; Wang, Xiao; Sun, Yanling; Liu, Juntao; Tong, Yan; Liu, Zhijing

    2016-11-01

    Based on the Pd(0)-catalyzed Tsuji-Trost allylic oxidative insertion reaction, we developed a fluorescent probe PdL1 for sensing Pd(0). As expected, probe PdL1 exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Pd(0) in CH3CH2OH/PBS (10 mM, pH = 7.4, 6:4, v/v) solution. The detection limit was calculated to be as low as 15 nM, which can meet the selective requirements for practical application.

  16. A high performance fluorescence switching system triggered electrochemically by Prussian blue with upconversion nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhai, Yiwen; Zhang, Hui; Zhang, Lingling; Dong, Shaojun

    2016-05-01

    A high performance fluorescence switching system triggered electrochemically by Prussian blue with upconversion nanoparticles was proposed. We synthesized a kind of hexagonal monodisperse β-NaYF4:Yb3+,Er3+,Tm3+ upconversion nanoparticle and manipulated the intensity ratio of red emission (at 653 nm) and green emission at (523 and 541 nm) around 2 : 1, in order to match well with the absorption spectrum of Prussian blue. Based on the efficient fluorescence resonance energy transfer and inner-filter effect of the as-synthesized upconversion nanoparticles and Prussian blue, the present fluorescence switching system shows obvious behavior with high fluorescence contrast and good stability. To further extend the application of this system in analysis, sulfite, a kind of important anion in environmental and physiological systems, which could also reduce Prussian blue to Prussian white nanoparticles leading to a decrease of the absorption spectrum, was chosen as the target. And we were able to determine the concentration of sulfite in aqueous solution with a low detection limit and a broad linear relationship.A high performance fluorescence switching system triggered electrochemically by Prussian blue with upconversion nanoparticles was proposed. We synthesized a kind of hexagonal monodisperse β-NaYF4:Yb3+,Er3+,Tm3+ upconversion nanoparticle and manipulated the intensity ratio of red emission (at 653 nm) and green emission at (523 and 541 nm) around 2 : 1, in order to match well with the absorption spectrum of Prussian blue. Based on the efficient fluorescence resonance energy transfer and inner-filter effect of the as-synthesized upconversion nanoparticles and Prussian blue, the present fluorescence switching system shows obvious behavior with high fluorescence contrast and good stability. To further extend the application of this system in analysis, sulfite, a kind of important anion in environmental and physiological systems, which could also reduce Prussian blue to

  17. High-precision correlative fluorescence and electron cryo microscopy using two independent alignment markers☆

    PubMed Central

    Schellenberger, Pascale; Kaufmann, Rainer; Siebert, C. Alistair; Hagen, Christoph; Wodrich, Harald; Grünewald, Kay

    2014-01-01

    Correlative light and electron microscopy (CLEM) is an emerging technique which combines functional information provided by fluorescence microscopy (FM) with the high-resolution structural information of electron microscopy (EM). So far, correlative cryo microscopy of frozen-hydrated samples has not reached better than micrometre range accuracy. Here, a method is presented that enables the correlation between fluorescently tagged proteins and electron cryo tomography (cryoET) data with nanometre range precision. Specifically, thin areas of vitrified whole cells are examined by correlative fluorescence cryo microscopy (cryoFM) and cryoET. Novel aspects of the presented cryoCLEM workflow not only include the implementation of two independent electron dense fluorescent markers to improve the precision of the alignment, but also the ability of obtaining an estimate of the correlation accuracy for each individual object of interest. The correlative workflow from plunge-freezing to cryoET is detailed step-by-step for the example of locating fluorescence-labelled adenovirus particles trafficking inside a cell. PMID:24262358

  18. Highly fluorescent gold nanoclusters based sensor for the detection of quercetin

    NASA Astrophysics Data System (ADS)

    Chen, Zhanguang; Qian, Sihua; Chen, Junhui; Chen, Xi

    2012-12-01

    In this contribution, novel luminescent gold nanoclusters were synthesized by utilizing bovine serum albumin as templates with a simple, rapid, and one-pot procedure. The as-prepared gold nanoclusters were highly dispersed in aqueous solution and emitted an intense red fluorescence under UV light (365 nm). They exhibited strong fluorescence and the maximum excitation and emission wavelengths were 480 and 613.5 nm. In addition, the bovine serum albumin-stabilized gold nanoclusters were successfully utilized as novel fluorescent probes for the detection of quercetin for the first time. It was found that the addition of quercetin induced the strong fluorescence intensity of the gold nanoclusters to decrease. The decrease in fluorescence intensity of the gold nanoclusters caused by quercetin allowed the sensitive detection of quercetin in the range of 8.9 × 10-8-1.8 × 10-4 mol L-1. The detection limit for quercetin is 1.8 × 10-8 mol L-1 at a signal-to-noise ratio of 3. The present sensor for quercetin detection possessed a low detection limit and wide linear range. In addition, the real samples were analyzed with satisfactory results.

  19. Highly selective and sensitive nanoprobes for cyanide based on gold nanoclusters with red fluorescence emission

    NASA Astrophysics Data System (ADS)

    Zhang, Guomei; Qiao, Yunyun; Xu, Ting; Zhang, Caihong; Zhang, Yan; Shi, Lihong; Shuang, Shaomin; Dong, Chuan

    2015-07-01

    We report a novel and environmentally friendly fluorescent probe for detecting the cyanide ion (CN-) using l-amino acid oxidase (LAAOx)-protected Au nanoclusters (LAAOx@AuNCs) with red emission. The fluorescence-based sensing behaviour of LAAOx@AuNCs towards anions was investigated in buffered aqueous media. Among the anions studied, CN- was found to effectively quench the fluorescence emission of AuNCs based on CN- induced Au core decomposition. Excellent sensitivity and selectivity toward the detection of CN- in aqueous solution were observed. The CN- detection limit was determined to be approximately 180 nM, which is 15 times lower than the maximum level (2700 nM) of CN- in drinking water permitted by the World Health Organization (WHO). A linear relationship between the fluorescence intensity and CN- concentration was observed in two ranges of CN- concentration, including 3.2 × 10-6 to 3.4 × 10-5 mol L-1 and 3.81 × 10-5 to 1.04 × 10-4 mol L-1. The high sensitivity and selectivity to CN- among the 17 types of anions make the AuNCs good candidates for use in fluorescent nanoprobes of CN-.

  20. A highly Selective Fluorescent Sensor for Monitoring Cu(2+) Ion: Synthesis, Characterization and Photophysical Properties.

    PubMed

    Aderinto, Stephen Opeyemi; Xu, Yuling; Peng, Hongping; Wang, Fei; Wu, Huilu; Fan, Xuyang

    2017-01-01

    A new fluorescent sensor, 4-allylamine-N-(N-salicylidene)-1,8-naphthalimide (1), anchoring a naphthalimide moiety as fluorophore and a Schiff base group as receptor, was synthesized and characterized. The photophysical properties of sensor 1 were conducted in organic solvents of different polarities. Our study revealed that, depending on the solvent polarity, the fluorescence quantum yields varied from 0.59 to 0.89. The fluorescent activity of the sensor was monitored and the sensor was consequently applied for the detection of Cu(2+) with high selectivity over various metal ions by fluorescence quenching in Tris-HCl (pH = 7.2) buffer/DMF (1:1, v/v) solution. From the binding stoichiometry, it was indicated that a 1:1 complex was formed between Cu(2+) and the sensor 1. The fluorescence intensity was linear with Cu(2+) in the concentration range 0.5-5 μM. Moreso, the detection limit was calculated to be 0.32 μM, which is sufficiently low for good sensitivity of Cu(2+) ion. The binding mode was due to the intramolecular charge transfer (ICT) and the coordination of Cu(2+) with C = N and hydroxyl oxygen groups of the sensor 1. The sensor proved effective for Cu(2+) monitoring in real water samples with recovery rates of 95-112.6 % obtained.

  1. Highly Luminescent π-Conjugated Terpyridine Derivatives Exhibiting Thermally Activated Delayed Fluorescence.

    PubMed

    Sasabe, Hisahiro; Hayasaka, Yuya; Komatsu, Ryutaro; Nakao, Kohei; Kido, Junji

    2017-01-01

    Typically, luminescent π-conjugated 2,2':6',2''-terpyridine (tpy) derivatives are versatile components for tridentate metal ligands, supramolecular materials, two-photon absorption bioimaging probes, fluorescent ion sensors, and organic light-emitting devices. However, a limited number of luminescent tpy materials, other than metal complexes, have been reported. This study introduces a series of π-conjugated tpy derivatives that exhibit strong thermally activated delayed fluorescence (TADF). We have observed that a blue tpy emitter outperforms conventional fluorescent emitters. Additionally, a green tpy emitter has exhibited a performance that is almost comparable to that of its green phosphorescent counterparts, realizing an external quantum efficiency close to 25 % and a power efficiency exceeding 80 lm W(-1) with an exceptionally low efficiency roll-off. This study demonstrates the first example of highly luminescent tpy-based TADF emitters.

  2. Highly colloidally stable hyperbranched polyglycerol grafted red fluorescent silicon nanoparticle as bioimaging probe.

    PubMed

    Das, Pradip; Jana, Nikhil R

    2014-03-26

    Here we report a surface modification approach for fluorescent silicon nanoparticle that transforms hydrophobic nanoparticle into water-soluble nanoparticle of high colloidal stability. The approach involves ring-opening polymerization of glycidol at the hydroxyl-terminated nanoparticle surface that results in a hyperbranched polyglycerol grafted silicon nanoparticle (Si-HPG). The resultant Si-HPG has 25 nm hydrodynamic diameter, low surface charge, and broad emission in the range of 450-700 nm with a fluorescence quantum yield of 6-9%. The Si-HPG has been transformed into cyclic RGD peptide functionalized nanoprobe using the conventional bioconjugation chemistry and used for specific targeting to αvβ3 integrin overexpressed cervical cancer cells and glioblastoma cells. Result shows that a silicon nanoparticle-based red fluorescent nanoprobe can be developed for in vitro/in vivo bioimaging applications.

  3. A novel high-sensitive miniaturized optical system for fluorescence detection

    NASA Astrophysics Data System (ADS)

    Yao, Mingjin; Fang, Ji

    2011-03-01

    This paper presents a novel, high sensitive and miniaturized fluorescence detection system which integrated a LED light source, all necessary optical components and a photodiode with preamplifier into one package about 2 cm x 2 cm x 2 cm especially for the applications of lab-on-a-chip, portable bio-detection system and point-of-care diagnostic system. The prototype has been tested using the fluorescence dye 5-Carboxyfluorescein (5-FAM) dissolved into solvent DMSO (Dimethyl Sulfoxide) and diluted with DI water as the testing solution samples. Resolution approximation method is accepted to evaluate the sensitivity. The testing results prove a remarkable sensitivity at pico-scale molar, around 1.08 pM/L, which should meet the most of bio-detection requirements. This cost-effective detection system can be widely integrated to the portable device and system for fluorescent detection in biological, chemical, medical, point-of-care applications.

  4. Demonstration of x-ray fluorescence imaging of a high-energy-density plasma

    SciTech Connect

    MacDonald, M. J. Gamboa, E. J.; Keiter, P. A.; Fein, J. R.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J.-E.; Wan, W. C.; Drake, R. P.; Montgomery, D. S.; Biener, M. M.; Fournier, K. B.; Streit, J.

    2014-11-15

    Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.

  5. High expression of CD26 accurately identifies human bacteria-reactive MR1-restricted MAIT cells

    PubMed Central

    Sharma, Prabhat K; Wong, Emily B; Napier, Ruth J; Bishai, William R; Ndung'u, Thumbi; Kasprowicz, Victoria O; Lewinsohn, Deborah A; Lewinsohn, David M; Gold, Marielle C

    2015-01-01

    Mucosa-associated invariant T (MAIT) cells express the semi-invariant T-cell receptor TRAV1–2 and detect a range of bacteria and fungi through the MHC-like molecule MR1. However, knowledge of the function and phenotype of bacteria-reactive MR1-restricted TRAV1–2+ MAIT cells from human blood is limited. We broadly characterized the function of MR1-restricted MAIT cells in response to bacteria-infected targets and defined a phenotypic panel to identify these cells in the circulation. We demonstrated that bacteria-reactive MR1-restricted T cells shared effector functions of cytolytic effector CD8+ T cells. By analysing an extensive panel of phenotypic markers, we determined that CD26 and CD161 were most strongly associated with these T cells. Using FACS to sort phenotypically defined CD8+ subsets we demonstrated that high expression of CD26 on CD8+ TRAV1–2+ cells identified with high specificity and sensitivity, bacteria-reactive MR1-restricted T cells from human blood. CD161hi was also specific for but lacked sensitivity in identifying all bacteria-reactive MR1-restricted T cells, some of which were CD161dim. Using cell surface expression of CD8, TRAV1–2, and CD26hi in the absence of stimulation we confirm that bacteria-reactive T cells are lacking in the blood of individuals with active tuberculosis and are restored in the blood of individuals undergoing treatment for tuberculosis. PMID:25752900

  6. High expression of CD26 accurately identifies human bacteria-reactive MR1-restricted MAIT cells.

    PubMed

    Sharma, Prabhat K; Wong, Emily B; Napier, Ruth J; Bishai, William R; Ndung'u, Thumbi; Kasprowicz, Victoria O; Lewinsohn, Deborah A; Lewinsohn, David M; Gold, Marielle C

    2015-07-01

    Mucosa-associated invariant T (MAIT) cells express the semi-invariant T-cell receptor TRAV1-2 and detect a range of bacteria and fungi through the MHC-like molecule MR1. However, knowledge of the function and phenotype of bacteria-reactive MR1-restricted TRAV1-2(+) MAIT cells from human blood is limited. We broadly characterized the function of MR1-restricted MAIT cells in response to bacteria-infected targets and defined a phenotypic panel to identify these cells in the circulation. We demonstrated that bacteria-reactive MR1-restricted T cells shared effector functions of cytolytic effector CD8(+) T cells. By analysing an extensive panel of phenotypic markers, we determined that CD26 and CD161 were most strongly associated with these T cells. Using FACS to sort phenotypically defined CD8(+) subsets we demonstrated that high expression of CD26 on CD8(+)  TRAV1-2(+) cells identified with high specificity and sensitivity, bacteria-reactive MR1-restricted T cells from human blood. CD161(hi) was also specific for but lacked sensitivity in identifying all bacteria-reactive MR1-restricted T cells, some of which were CD161(dim) . Using cell surface expression of CD8, TRAV1-2, and CD26(hi) in the absence of stimulation we confirm that bacteria-reactive T cells are lacking in the blood of individuals with active tuberculosis and are restored in the blood of individuals undergoing treatment for tuberculosis.

  7. Moving Overlapping Grids with Adaptive Mesh Refinement for High-Speed Reactive and Non-reactive Flow

    SciTech Connect

    Henshaw, W D; Schwendeman, D W

    2005-08-30

    We consider the solution of the reactive and non-reactive Euler equations on two-dimensional domains that evolve in time. The domains are discretized using moving overlapping grids. In a typical grid construction, boundary-fitted grids are used to represent moving boundaries, and these grids overlap with stationary background Cartesian grids. Block-structured adaptive mesh refinement (AMR) is used to resolve fine-scale features in the flow such as shocks and detonations. Refinement grids are added to base-level grids according to an estimate of the error, and these refinement grids move with their corresponding base-level grids. The numerical approximation of the governing equations takes place in the parameter space of each component grid which is defined by a mapping from (fixed) parameter space to (moving) physical space. The mapped equations are solved numerically using a second-order extension of Godunov's method. The stiff source term in the reactive case is handled using a Runge-Kutta error-control scheme. We consider cases when the boundaries move according to a prescribed function of time and when the boundaries of embedded bodies move according to the surface stress exerted by the fluid. In the latter case, the Newton-Euler equations describe the motion of the center of mass of the each body and the rotation about it, and these equations are integrated numerically using a second-order predictor-corrector scheme. Numerical boundary conditions at slip walls are described, and numerical results are presented for both reactive and non-reactive flows in order to demonstrate the use and accuracy of the numerical approach.

  8. Seesawed fluorescence nano-aptasensor based on highly vertical ZnO nanorods and three-dimensional quantitative fluorescence imaging for enhanced detection accuracy of ATP.

    PubMed

    Shrivastava, Sajal; Triet, Nguyen Minh; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

    2017-04-15

    Probe-mediated fluorescence biosensing methods based on spectrophotometry still have limitations such as detection inaccuracy caused by the occurrence of false signals and lack of simultaneous qualitative and quantitative read-outs with an ultra-low detection limit. Herein, we describe a novel seesawed fluorescence detection strategy based on dual-colour imaging-based quantitation in which the green fluorescence of the capture aptamer decreases and the red fluorescence of the detection aptamer increases simultaneously upon their respective interactions with the target biomolecule. This approach enhances detection accuracy through facilitating identification of probable false-positives in biological samples. Furthermore, combining the seesawed detection scheme with three-dimensional imaging of fluorescence signal enhanced by highly vertical ZnO nanorods increases signal-to-noise ratio, which addresses the limited performance of digital cameras and, in turn, enhances sensitivity and dynamic range. This simple, robust, scalable, imaging-based and label-free fluorescence method allows highly specific and sensitive quantification of biomolecules with excellent reliability.

  9. Violent offenders respond to provocations with high amygdala and striatal reactivity.

    PubMed

    da Cunha-Bang, Sofi; MacDonald Fisher, Patrick; Vadskjær Hjordt, Liv; Perfalk, Erik; Persson Skibsted, Anine; Bock, Camilla; Ohlhues Baandrup, Anders; Deen Christensen, Marie; Thomsen, Carsten; Sestoft, Dorte; Knudsen, Gitte M

    2017-03-08

    The ability to successfully suppress impulses and angry affect is fundamental to control aggressive reactions following provocations. The aim of this study was to examine neural responses to provocations and aggression using a laboratory model of reactive aggression. We used a novel functional magnetic resonance imaging point-subtraction aggression paradigm in 44 men, of whom 18 were incarcerated violent offenders and 26 were control non-offenders. We measured brain activation following provocations (monetary subtractions), while the subjects had the possibility to behave aggressively or pursue monetary rewards. The violent offenders behaved more aggressively than controls (aggression frequency 150 vs. 84, p = 0.03) and showed significantly higher brain reactivity to provocations within the amygdala and striatum, as well as reduced amygdala-prefrontal and striato-prefrontal connectivity. Amygdala reactivity to provocations was positively correlated with task-related behavior in the violent offenders. Across groups, striatal and prefrontal reactivity to provocations were positively associated with trait anger and trait aggression. These results suggest that violent individuals display abnormally high neural sensitivity to social provocations, a sensitivity related to aggressive behavior. These findings provide novel insight into the neural pathways that are sensitive to provocations, which is critical to more effectively shape interventions that aim to reduce pathological aggressive behavior.

  10. Understanding the Reactivity of Lunar Dust for Future Lunar Missions

    NASA Technical Reports Server (NTRS)

    Wallace, W. T.; Jeevarajan, A. S.; Taylor, L. A.

    2010-01-01

    Fluorescence and EPR can be used to measure the reactivity of lunar soil. Lunar soil is highly activated by grinding. Reactivity is dependent upon soil maturity and locale. Maturity is based on the amount of nanophase iron (np-Fe) in a soil relative to the total iron (FeO). Lunar soil activity ia a direct function of the amount of np-Fe present. Reactive soil can be "deactivated" by humid atmosphere.

  11. Laser induced fluorescence measurements and modeling of nitric oxide in high-pressure premixed flames

    NASA Technical Reports Server (NTRS)

    Reisel, John R.; Laurendeau, Normand M.

    1994-01-01

    Laser-induced fluorescence (LIF) has been applied to the quantitative measurement of nitric oxide (NO) in premixed, laminar, high-pressure flames. Their chemistry was also studied using three current kinetics schemes to determine the predictive capabilities of each mechanism with respect to NO concentrations. The flames studied were low-temperature (1600 less than T less than 1850K) C2H6/O2/N2 and C2H6/O2/N2 flames, and high temperature (2100 less than T less than 2300K) C2H6/O2/N2 flames. Laser-saturated fluorescence (LSF) was initially used to measure the NO concentrations. However, while the excitation transition was well saturated at atmospheric pressure, the fluorescence behavior was basically linear with respect to laser power at pressures above 6 atm. Measurements and calculations demonstrated that the fluorescence quenching rate variation is negligible for LIF measurements of NO at a given pressure. Therefore, linear LIF was used to perform quantitative measurements of NO concentration in these high-pressure flames. The transportability of a calibration factor from one set of flame conditions to another also was investigated by considering changes in the absorption and quenching environment for different flame conditions. The feasibility of performing LIF measurements of (NO) in turbulent flames was studied; the single-shot detection limit was determined to be 2 ppm.

  12. Highly sensitive determination of nitric oxide in biologic samples by a near-infrared BODIPY-based fluorescent probe coupled with high-performance liquid chromatography.

    PubMed

    Zhang, Hui-Xian; Chen, Jian-Bo; Guo, Xiao-Feng; Wang, Hong; Zhang, Hua-Shan

    2013-11-15

    Nitric oxide (NO) acts as an important regulator and mediator in numerous processes of biological systems. In this work, the analytical potential of a novel near-infrared (NIR, >600 nm) BODIPY-based fluorescent probe for NO, 8-(3,4-diaminophenyl)-4,4-difluoro-4-bora-3a,4a-diaza-di(1,2-dihydro) naphtho[b, g]s-indacene (DANPBO-H) has been evaluated in high performance liquid chromatography (HPLC). In 25 mM pH 6.50 borate buffer, DANPBO-H reacted with NO to give the corresponding triazole, DANPBO-H-T, at 35 °C for 20 min. DANPBO-H-T was eluted using a mobile phase of methanol/tetrahydrofuran/50mM pH 7.00 H3Cit-NaOH buffer (81:7:12, v/v/v) in 4 min on a C8 column and detected with fluorescence detection at excitation and emission wavelengths of 621 and 631 nm, respectively. The limit of detection (LOD) (signal-to-noise=3) reached to 5.50×10(-10) M. Excellent selectivity was observed against other reactive oxygen/nitrogen species. Various representative biological matrixes including the whole blood and organs of mice, the pangen and radical of rice, human vascular endothelial (ECV-304) cells and mouse macrophage (RAW 264.7) cells were used to verify the feasibility and resistance to interfering effects from complex biological sample matrixes of the developed DANPBO-H-based HPLC method. Compared to the existing derivatization-based HPLC methods for NO, the proposed method eliminates interfering effects from complex biological sample matrixes efficiently owing to the fluorescence detection in the NIR region, and is more advantageous and robust for the sensitive and selective determination of NO in complex biological samples.

  13. Development of a Fluorescence-Based, Ultra High-Throughput Screening Platform for Nanoliter-Scale Cytochrome P450 Microarrays

    PubMed Central

    Sukumaran, Sumitra M.; Potsaid, Benjamin; Lee, Moo-yeal; Clark, Douglas S.; Dordick, Jonathan S.

    2017-01-01

    Cytochrome P450 enzyme (CYP450s) assays are critical enzymes in early-stage lead discovery and optimization in drug development. Currently available fluorescence-based reaction assays provide a rapid and reliable method for monitoring CYP450 enzyme activity but are confined to medium-throughput well-plate systems. The authors present a high-throughput, integrated screening platform for CYP450 assays combining enzyme encapsulation techniques, microarraying methods, and wide-field imaging. Alginate-containing microarrays consisting of up to 1134 CYP450 reaction elements were fabricated on functionalized glass slides (reaction volumes 20 to 80 nL, total enzyme content in pg) and imaged to yield endpoint activity, stability, and kinetic data. A charge-coupled device imager acquired quantitative, high-resolution images of a 20 × 20 mm area/snapshot using custom-built wide-field optics with telecentric lenses and easily interchangeable filter sets. The imaging system offered a broad dynamic intensity range (linear over 3 orders of magnitude) and sensitivity down to fluorochrome quantities of <5 fmols, with read accuracy similar to a laser scanner or a fluorescence plate reader but with higher throughput. Rapid image acquisition enabled analysis of CYP450 kinetics. Fluorogenic assays with CYP3A4, CYP2C9, and CYP2D6 on the alginate microarrays exhibited Z′ factors ranging from 0.75 to 0.85, sensitive detection of inhibitory compounds, and reactivity comparable to that in solution, thereby demonstrating the reliability and accuracy of the microarray platform. This system enables for the first time a significant miniaturization of CYP enzyme assays with significant conservation of assay reagents, greatly increased throughput, and no apparent loss of enzyme activity or assay sensitivity. PMID:19525490

  14. High throughput and high yield nanofabrication of precisely designed gold nanohole arrays for fluorescence enhanced detection of biomarkers.

    PubMed

    Wong, Ten It; Han, Shan; Wu, Lin; Wang, Yi; Deng, Jie; Tan, Christina Yuan Ling; Bai, Ping; Loke, Yee Chong; Yang, Xin Da; Tse, Man Siu; Ng, Sum Huan; Zhou, Xiaodong

    2013-06-21

    Fluorescence excitation enhancement by plasmonic nanostructures such as gold nanohole arrays has been a hot topic in biosensing and bioimaging in recent years. However, the high throughput and high yield fabrication of precisely designed metal nanostructures for optimized fluorescence excitation remains a challenge. Our work is the first report combining nanopattern nickel mould fabrication and UV imprinting for gold nanostructure mass fabrication in high yield. We report our successful gold nanohole array mass fabrication on a 4'' glass wafer, by first fabricating a high fidelity nickel mould, then using the mould for UV nanoimprinting on a polymer coated on the glass, evaporating the gold film on the glass wafer, and lifting off the polymer to obtain a gold nanohole array on the glass. Our optimized process for wafer fabrication can achieve almost 100% yield from nanoimprinting to gold lift-off, while the fabricated nickel mould has >70% defect-free area with the rest having a few scattered defects. In our work, the size and pitch of the gold nanohole array are designed to enhance the fluorescent dye Alexa 647. When the fabricated gold nanohole array is used for prostate specific antigen (PSA) detection by establishing a sandwiched fluorescence assay on the gold surface, a detection limit of 100 pg ml(-1) is achieved, while with a same thickness of gold film, only 1 ng ml(-1) is detected.

  15. Super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging

    NASA Astrophysics Data System (ADS)

    Wei, Lu; Zhu, Xinxin; Chen, Zhixing; Min, Wei

    2014-02-01

    Two-photon excited fluorescence microscopy (TPFM) offers the highest penetration depth with subcellular resolution in light microscopy, due to its unique advantage of nonlinear excitation. However, a fundamental imaging-depth limit, accompanied by a vanishing signal-to-background contrast, still exists for TPFM when imaging deep into scattering samples. Formally, the focusing depth, at which the in-focus signal and the out-of-focus background are equal to each other, is defined as the fundamental imaging-depth limit. To go beyond this imaging-depth limit of TPFM, we report a new class of super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging, including multiphoton activation and imaging (MPAI) harnessing novel photo-activatable fluorophores, stimulated emission reduced fluorescence (SERF) microscopy by adding a weak laser beam for stimulated emission, and two-photon induced focal saturation imaging with preferential depletion of ground-state fluorophores at focus. The resulting image contrasts all exhibit a higher-order (third- or fourth- order) nonlinear signal dependence on laser intensity than that in the standard TPFM. Both the physical principles and the imaging demonstrations will be provided for each super-nonlinear microscopy. In all these techniques, the created super-nonlinearity significantly enhances the imaging contrast and concurrently extends the imaging depth-limit of TPFM. Conceptually different from conventional multiphoton processes mediated by virtual states, our strategy constitutes a new class of fluorescence microscopy where high-order nonlinearity is mediated by real population transfer.

  16. 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%.

  17. Metal-Enhanced Fluorescence from Silver Nanowires with High Aspect Ratio on Glass Slides for Biosensing Applications

    PubMed Central

    2015-01-01

    High enhancement of fluorescence emission, improved fluorophore photostability, and significant reduction of fluorescence lifetimes have been obtained from high aspect ratio (>100) silver (Ag) nanowires. These quantities are found to depend on the surface loading of Ag nanowires on glass slides, where the enhancement of fluorescence emission increases with the density of nanowires. The surface loading dependence was attributed to the creation of intense electric fields around the network of Ag nanowires and to the coupling of fluorophore excited states that takes place efficiently at a distance of 10 nm from the surface of nanowires, which was confirmed by theoretical calculations. The enhancement of fluorescence emission of fluorescein isothiocyanate (FITC) was assessed by fluorescence spectroscopy and fluorescence-lifetime imaging microscopy (FLIM) to demonstrate the potential of high aspect ratio Ag nanowires. Fluorescence enhancement factors exceeding 14 were observed on Ag nanowires with high loading by FLIM. The photostability of FITC was the highest on nanowires with medium loading under continuous laser excitation for 10 min because of the significant reduction in the fluorescence lifetime of FITC on these surfaces. These results clearly demonstrate the potential of Ag nanowires in metal-enhanced fluorescence-based applications of biosensing on planar surfaces and cellular imaging. PMID:25598859

  18. Experimental Detection of Branching at a Conical Intersection in a Highly Fluorescent Molecule.

    PubMed

    Brazard, Johanna; Bizimana, Laurie A; Gellen, Tobias; Carbery, William P; Turner, Daniel B

    2016-01-07

    Conical intersections are molecular configurations at which adiabatic potential-energy surfaces touch. They are predicted to be ubiquitous, yet condensed-phase experiments have focused on the few systems with clear spectroscopic signatures of negligible fluorescence, high photoactivity, or femtosecond electronic kinetics. Although rare, these signatures have become diagnostic for conical intersections. Here we detect a coherent surface-crossing event nearly two picoseconds after optical excitation in a highly fluorescent molecule that has no photoactivity and nanosecond electronic kinetics. Time-frequency analysis of high-sensitivity measurements acquired using sub-8 fs pulses reveals phase shifts of the signal due to branching of the wavepacket through a conical intersection. The time-frequency analysis methodology demonstrated here on a model compound will enable studies of conical intersections in molecules that do not exhibit their diagnostic signatures. Improving the ability to detect conical intersections will enrich the understanding of their mechanistic role in molecular photochemistry.

  19. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  20. Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

    PubMed Central

    Maier, Maximilian; Schmidt, Magnus S; Ringwald, Markus

    2017-01-01

    Six polymerizable N,N’-diacylamides containing spatially arranged N-acryl, N-allyl and/or N-alkyl groups were prepared via two-step syntheses and characterized by 1H/13C NMR-spectra, refractive index (RI) and viscosity measurements. Photo DSC measurements on activated samples provided reactivity parameters ∆H p, R p,max and t max, while FTIR spectra before and after curing elucidated the underlying polymerization mechanism. Mechanical testing of the obtained polymers exhibited gradual differences in network densities, depending on the intramolecular arrangement and number of functional groups. Overall, a general building principle for highly reactive, liquid diacrylamides via synergistic combination of optimally arranged functional groups could be identified. The highest possible level of intramolecular synergism was found for low viscous N,N'-diacryloyl-N,N'-diallyl-1,4-but-2-enediamine. PMID:28382175

  1. Guidelines for application of fluorescent lamps in high-performance avionic backlight systems

    NASA Astrophysics Data System (ADS)

    Syroid, Daniel D.

    1997-07-01

    Fluorescent lamps have proven to be well suited for use in high performance avionic backlight systems as demonstrated by numerous production applications for both commercial and military cockpit displays. Cockpit display applications include: Boeing 777, new 737s, F-15, F-16, F-18, F-22, C- 130, Navy P3, NASA Space Shuttle and many others. Fluorescent lamp based backlights provide high luminance, high lumen efficiency, precision chromaticity and long life for avionic active matrix liquid crystal display applications. Lamps have been produced in many sizes and shapes. Lamp diameters range from 2.6 mm to over 20 mm and lengths for the larger diameter lamps range to over one meter. Highly convoluted serpentine lamp configurations are common as are both hot and cold cathode electrode designs. This paper will review fluorescent lamp operating principles, discuss typical requirements for avionic grade lamps, compare avionic and laptop backlight designs and provide guidelines for the proper application of lamps and performance choices that must be made to attain optimum system performance considering high luminance output, system efficiency, dimming range and cost.

  2. Effect of gamma irradiation on reactivity of rinderpest virus antigen with bovine immune serum in enzyme-linked immunosorbent assays and virus neutralization and indirect fluorescent-antibody tests.

    PubMed Central

    Saliki, J T; Berninger, M L; Torres, A; House, J A; Mebus, C A; Dubovi, E J

    1993-01-01

    Gamma irradiation effectively inactivated gradient-purified rinderpest virus. Irradiated antigen and sera remained functional in enzyme-linked immunosorbent assays, virus neutralization tests, and indirect fluorescent-antibody tests. Irradiation, however, led to a dose-dependent decrease in reactivity, particularly significant (P < 0.05) when both reagents were irradiated. To avoid false-positive reactions, only one reagent (serum or antigen) may be irradiated. PMID:8432831

  3. Green fluorescent protein retroviral vectors: low titer and high recombination frequency suggest a selective disadvantage.

    PubMed

    Hanazono, Y; Yu, J M; Dunbar, C E; Emmons, R V

    1997-07-20

    Green fluorescent protein (GFP) has been used as a reporter molecule for gene expression because it fluoresces green after blue-light excitation. Inclusion of this gene in a vector could allow rapid, nontoxic selection of successfully transduced cells. However, many attempts by our laboratory to isolate stable retroviral producer cell clones secreting biologically active vectors containing either the highly fluorescent S65T-GFP mutant or humanized GFP have failed. Vector plasmids containing various forms of GFP and the neomycin resistance gene were transfected into three different packaging cell lines and fluorescence was observed for several days, but stable clones selected with G418 no longer fluoresced. Using confocal microscopy, the brightest cells were observed to contract and die within a matter of days. RNA slot-blot analysis of retroviral producer supernatants showed no viral production from the GFP plasmid-transfected clones, although all clones derived after transfection with an identical retroviral construct not containing GFP produced virus. Genomic Southern analysis of the GFP-transduced clones showed a much higher probability of rearrangement of the priviral sequences than in the control non-GFP clones. Overall, 18/34 S65T-GFP clones and 17/33 humanized-GFP clones had rearrangements, whereas 2/15 control non-GFP clones had rearrangements. Hence, producer cells expressing high levels of these GFP genes seem to be selected against, with stable clones undergoing major rearrangements or other mutations that both abrogate GFP expression and prevent vector production. These observations indicate that GFP may not be an appropriate reporter gene for gene transfer applications in our vector/packaging system.

  4. In vivo and in situ tracking cancer chemotherapy by highly photostable NIR fluorescent theranostic prodrug.

    PubMed

    Wu, Xumeng; Sun, Xuanrong; Guo, Zhiqian; Tang, Jianbin; Shen, Youqing; James, Tony D; Tian, He; Zhu, Weihong

    2014-03-05

    In vivo monitoring of the biodistribution and activation of prodrugs is urgently required. Near infrared (NIR) fluorescence-active fluorophores with excellent photostability are preferable for tracking drug release in vivo. Herein, we describe a NIR prodrug DCM-S-CPT and its polyethylene glycol-polylactic acid (PEG-PLA) loaded nanoparticles as a potent cancer therapy. We have conjugated a dicyanomethylene-4H-pyran derivative as the NIR fluorophore with camptothecin (CPT) as the anticancer drug using a disulfide linker. In vitro experiments verify that the high intracellular glutathione (GSH) concentrations in tumor cells cause cleavage of the disulfide linker, resulting in concomitantly the active drug CPT release and significant NIR fluorescence turn-on with large Stokes shift (200 nm). The NIR fluorescence of DCM-S-CPT at 665 nm with fast response to GSH can act as a direct off-on signal reporter for the GSH-activatable prodrug. Particularly, DCM-S-CPT possesses much better photostability than ICG, which is highly desirable for in situ fluorescence-tracking of cancer chemotherapy. DCM-S-CPT has been successfully utilized for in vivo and in situ tracking of drug release and cancer therapeutic efficacy in living animals by NIR fluorescence. DCM-S-CPT exhibits excellent tumor-activatable performance when intravenously injected into tumor-bearing nude mice, as well as specific cancer therapy with few side effects. DCM-S-CPT loaded in PEG-PLA nanoparticles shows even higher antitumor activity than free CPT, and is also retained longer in the plasma. The tumor-targeting ability and the specific drug release in tumors make DCM-S-CPT as a promising prodrug, providing significant advances toward deeper understanding and exploration of theranostic drug-delivery systems.

  5. High Ki-67 Immunohistochemical Reactivity Correlates With Poor Prognosis in Bladder Carcinoma

    PubMed Central

    Luo, Yihuan; Zhang, Xin; Mo, Meile; Tan, Zhong; Huang, Lanshan; Zhou, Hong; Wang, Chunqin; Wei, Fanglin; Qiu, Xiaohui; He, Rongquan; Chen, Gang

    2016-01-01

    Abstract Ki-67 is considered as one of prime biomarkers to reflect cell proliferation and immunohistochemical Ki-67 staining has been widely applied in clinical pathology. To solve the widespread controversy whether Ki-67 reactivity significantly predicts clinical prognosis of bladder carcinoma (BC), we performed a comprehensive meta-analysis by combining results from different literature. A comprehensive search was conducted in the Chinese databases of WanFang, China National Knowledge Infrastructure and Chinese VIP as well as English databases of PubMed, ISI web of science, EMBASE, Science Direct, and Wiley online library. Independent studies linking Ki-67 to cancer-specific survival (CSS), disease-free survival (DFS), overall survival (OS), progression-free survival (PFS), and recurrence-free survival (RFS) were included in our meta-analysis. With the cut-off values literature provided, hazard ratio (HR) values between the survival distributions were extracted and later combined with STATA 12.0. In total, 76 studies (n = 13,053 patients) were eligible for the meta-analysis. It was indicated in either univariate or multivariate analysis for survival that high Ki-67 reactivity significantly predicted poor prognosis. In the univariate analysis, the combined HR for CSS, DFS, OS, PFS, and RFS were 2.588 (95% confidence interval [CI]: 1.623–4.127, P < 0.001), 2.697 (95%CI: 1.874–3.883, P < 0.001), 2.649 (95%CI: 1.632–4.300, P < 0.001), 3.506 (95%CI: 2.231–5.508, P < 0.001), and 1.792 (95%CI: 1.409–2.279, P < 0.001), respectively. The pooled HR of multivariate analysis for CSS, DFS, OS, PFS, and RFS were 1.868 (95%CI: 1.343–2.597, P < 0.001), 2.626 (95%CI: 2.089–3.301, P < 0.001), 1.104 (95%CI: 1.008–1.209, P = 0.032), 1.518 (95%CI: 1.299–1.773, P < 0.001), and 1.294 (95%CI: 1.203–1.392, P < 0.001), respectively. Subgroup analysis of univariate analysis by origin showed that Ki-67 reactivity significantly

  6. Effect of high temperature on photosynthesis in beans. I. Oxygen evolution and chlorophyll fluorescence

    SciTech Connect

    Pastenes, C.; Horton, P.

    1996-11-01

    We studied the effect of increasing temperature on photosynthesis in two bean (Phaseolus vulgaris L.) varieties known to differ in their resistance to extreme high temperatures, Blue Lake (BL), commercially available in the United Kingdom, and Barbucho (BA), noncommercially bred in Chile. We paid particular attention to the energy-transducing mechanisms and structural responses inferred from fluorescence kinetics. The study was conducted in non-photorespiratory conditions. Increases in temperature resulted in changes in the fluorescence parameters nonphotochemical quenching (qN) and photochemical quenching (qP) in both varieties, but to a different extent. In BL and BA the increase in qP and the decrease in qN were either completed at 30{degrees}C. No indication of photoinhibition was detected at any temperature, and the ratio of the quantum efficiencies of photosystem II (PSII) and O{sub 2} evolution remained constant from 20 to 35{degrees}C. Measurements of 77-K fluorescence showed an increase in the photosystem I (PSI)/PSII ratio with temperature, suggesting an increase in the state transitions. In addition, measurements of fast-induction fluorescence revealed that the proportion of PSII{sub {beta}} centers increased with increasing temperatures. The extent of both changes were maximum at 30 to 35{degrees}C, coinciding with the ratio of rates at temperatures differing by 10{degrees}C for oxygen evolution. 40 refs., 4 figs.

  7. Labeling and purification of cellulose-binding proteins for high resolution fluorescence applications.

    PubMed

    Moran-Mirabal, Jose M; Corgie, Stephane C; Bolewski, Jacob C; Smith, Hanna M; Cipriany, Benjamin R; Craighead, Harold G; Walker, Larry P

    2009-10-01

    The study of enzymatic reactions through fluorescence spectroscopy requires the use of bright, functional fluorescent molecules. In the case of proteins, labeling with fluorescent dyes has been carried out through covalent reactions with specific amino acids. However, these reactions are probabilistic and can yield mixtures of unlabeled and labeled enzymes with catalytic activities that can be modified by the addition of fluorophores. To have meaningful interpretations of results from the study of labeled enzymes, it is then necessary to reduce the variability in physical, chemical, and biological characteristics of the labeled products. In this paper, a solid phase labeling protocol is described as an advantageous alternative to free solution labeling of cellulose-binding proteins and is applied to tag cellulases with three different fluorophores. The products from the labeling reactions were purified to remove the unreacted dye and separate labeled and unlabeled enzymes. Characterization of the catalytic and spectroscopic properties of the isolated labeled species confirmed that highly homogeneous populations of labeled cellulases can be achieved. The protocol for the separation of labeled products is applicable to any mixture of labeled proteins, making this an attractive methodology for the production of labeled proteins suitable for single molecule fluorescence spectroscopy.

  8. Effect of High Temperature on Photosynthesis in Beans (I. Oxygen Evolution and Chlorophyll Fluorescence).

    PubMed Central

    Pastenes, C.; Horton, P.

    1996-01-01

    We studied the effect of increasing temperature on photosynthesis in two bean (Phaseolus vulgaris L.) varieties known to differ in their resistance to extreme high temperatures, Blue Lake (BL), commercially available in the United Kingdom, and Barbucho (BA), noncommercially bred in Chile. We paid particular attention to the energy-transducing mechanisms and structural responses inferred from fluorescence kinetics. The study was conducted in non-photorespiratory conditions. Increases in temperature resulted in changes in the fluorescence parameters nonphotochemical quenching (qN) and photochemical quenching (qP) in both varieties, but to a different extent. In BL and BA the increase in qP and the decrease in qN were either completed at 30[deg]C or slightly changed following increases from 30 to 35[deg]C. No indication of photoinhibition was detected at any temperature, and the ratio of the quantum efficiencies of photosystem II (PSII) and O2 evolution remained constant from 20 to 35[deg]C. Measurements of 77-K fluorescence showed an increase in the photosystem I (PSI)/PSII ratio with temperature, suggesting an increase in the state transitions. In addition, measurements of fast-induction fluorescence revealed that the proportion of PSII[beta] centers increased with increasing temperatures. The extent of both changes were maximum at 30 to 35[deg]C, coinciding with the ratio of rates at temperatures differing by 10[deg]C for oxygen evolution. PMID:12226442

  9. An adaptive sampling algorithm for Doppler-shift fluorescence velocimetry in high-speed flows

    NASA Astrophysics Data System (ADS)

    Le Page, Laurent M.; O'Byrne, Sean

    2017-03-01

    We present an approach to improving the efficiency of obtaining samples over a given domain for the peak location of Gaussian line-shapes. The method uses parameter estimates obtained from previous measurements to determine subsequent sampling locations. The method may be applied to determine the location of a spectral peak, where the monetary or time cost is too high to allow a less efficient search method, such as sampling at uniformly distributed domain locations, to be used. We demonstrate the algorithm using linear least-squares fitting of log-scaled planar laser-induced fluorescence data combined with Monte-Carlo simulation of measurements, to accurately determine the Doppler-shifted fluorescence peak frequency for each pixel of a fluorescence image. A simulated comparison between this approach and a uniformly spaced sampling approach is carried out using fits both for a single pixel and for a collection of pixels representing the fluorescence images that would be obtained in a hypersonic flow facility. In all cases, the peak location of Doppler-shifted line-shapes were determined to a similar precision with fewer samples than could be achieved using the more typical uniformly distributed sampling approach.

  10. Masked illumination scheme for a galvanometer scanning high-speed confocal fluorescence microscope.

    PubMed

    Kim, Dong Uk; Moon, Sucbei; Song, Hoseong; Kwon, Hyuk-Sang; Kim, Dug Young

    2011-01-01

    High-speed beam scanning and data acquisition in a laser scanning confocal microscope system are normally implemented with a resonant galvanometer scanner and a frame grabber. However, the nonlinear scanning speed of a resonant galvanometer can generate nonuniform photobleaching in a fluorescence sample as well as image distortion near the edges of a galvanometer scanned fluorescence image. Besides, incompatibility of signal format between a frame grabber and a point detector can lead to digitization error during data acquisition. In this article, we introduce a masked illumination scheme which can effectively decrease drawbacks in fluorescence images taken by a laser scanning confocal microscope with a resonant galvanometer and a frame grabber. We have demonstrated that the difference of photobleaching between the center and the edge of a fluorescence image can be reduced from 26 to 5% in our confocal laser scanning microscope with a square illumination mask. Another advantage of our masked illumination scheme is that the zero level or the lowest input level of an analog signal in a frame grabber can be accurately set by the dark area of a mask in our masked illumination scheme. We have experimentally demonstrated the advantages of our masked illumination method in detail.

  11. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    SciTech Connect

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  12. Role of high-sensitivity C-reactive protein measurements in HIV patients

    PubMed Central

    Vishwanath, Arun; Quaiser, Saif; Khan, Ruhi

    2016-01-01

    As we herald into the 21st century, the quality of life and the repertoire of highly active antiretroviral therapy (HAART) have considerably improved. However, considerable work is still needed to educate the population about primary and secondary prevention modalities. Moreover, regular monitoring of immune response with patients on HAART with conventional biomarkers is still a problem in low resource settings which needs to be addressed. We aim to review high-sensitivity C-reactive protein as a potential biomarker in this regard. PMID:27890944

  13. Observations of fluorescent and biological aerosol at a high-altitude site in Central France

    NASA Astrophysics Data System (ADS)

    Gabey, A. M.; Vaitilingom, M.; Freney, E.; Boulon, J.; Sellegri, K.; Gallagher, M. W.; Crawford, I. P.; Robinson, N. H.; Stanley, W. R.; Kaye, P. H.

    2013-01-01

    more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that pdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles. Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer.

  14. Observations of fluorescent and biological aerosol at a high-altitude site in central France

    NASA Astrophysics Data System (ADS)

    Gabey, A. M.; Vaitilingom, M.; Freney, E.; Boulon, J.; Sellegri, K.; Gallagher, M. W.; Crawford, I. P.; Robinson, N. H.; Stanley, W. R.; Kaye, P. H.

    2013-08-01

    an aerosol mass spectrometer (AMS; Aerodyne Inc.) suggests that aerosol reaching the site at night was more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that PdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles. Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer.

  15. Green synthesis of highly fluorescent carbon quantum dots from sugarcane bagasse pulp

    NASA Astrophysics Data System (ADS)

    Thambiraj, S.; Ravi Shankaran, D.

    2016-12-01

    Carbon quantum dots (CQDs) have great potential due to its advantageous characteristics of highly fluorescent nature and good stability. In this study, we aimed to develop a simple and efficient method for the green synthesis of fluorescent CQDs from sugarcane bagasse, a renewable and sustainable resource. The process involves the top down approach of chemical oxidation followed by exfoliation of sugarcane carbon. The synthesized CQDs was characterized by UV-vis absorption spectroscopy, Spectrofluorophotometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, X-ray photon spectroscopy (XPS), Atomic force microscopy (AFM) and High-resolution transmission electron microscopy (HR-TEM). The synthesized CQDs possess stable fluorescent properties, good bio-compatibility and high quantum yield. The CQDs are highly crystalline with longitudinal dimensions of 4.1 ± 0.17 nm with an average roughness of around 5 nm. The XRD and TEM analysis indicates that the synthesized CQDs possess face centred cubic crystal structure. The results suggest that the proposed CQDs could be utilized for bio-sensor, bio-imaging and drug delivery applications.

  16. HyperSpectral imaging microscopy for identification and quantitative analysis of fluorescently-labeled cells in highly autofluorescent tissue

    PubMed Central

    Leavesley, Silas J.; Annamdevula, Naga; Boni, John; Stocker, Samantha; Grant, Kristin; Troyanovsky, Boris; Rich, Thomas C.; Alvarez, Diego F.

    2012-01-01

    Standard fluorescence microscopy approaches rely on measurements at single excitation and emission bands to identify specific fluorophores and the setting of thresholds to quantify fluorophore intensity. This is often insufficient to reliably resolve and quantify fluorescent labels in tissues due to high autofluorescence. Here we describe the use of hyperspectral analysis techniques to resolve and quantify fluorescently labeled cells in highly autofluorescent lung tissue. This approach allowed accurate detection of green fluorescent protein (GFP) emission spectra, even when GFP intensity was as little as 15% of the autofluorescence intensity. GFP-expressing cells were readily quantified with zero false positives detected. In contrast, when the same images were analyzed using standard (single-band) thresholding approaches, either few GFP cells (high thresholds) or substantial false positives (intermediate and low thresholds) were detected. These results demonstrate that hyperspectral analysis approaches uniquely offer accurate and precise detection and quantification of fluorescence signals in highly autofluorescent tissues. PMID:21987373

  17. Designing the nanobiointerface of fluorescent nanodiamonds: highly selective targeting of glioma cancer cells

    NASA Astrophysics Data System (ADS)

    Slegerova, Jitka; Hajek, Miroslav; Rehor, Ivan; Sedlak, Frantisek; Stursa, Jan; Hruby, Martin; Cigler, Petr

    2014-12-01

    Core-shell nanoparticles based on fluorescent nanodiamonds coated with a biocompatible N-(2-hydroxypropyl)methacrylamide copolymer shell were developed for background-free near-infrared imaging of cancer cells. The particles showed excellent colloidal stability in buffers and culture media. After conjugation with a cyclic RGD peptide they selectively targeted integrin αvβ3 receptors on glioblastoma cells with high internalization efficacy.Core-shell nanoparticles based on fluorescent nanodiamonds coated with a biocompatible N-(2-hydroxypropyl)methacrylamide copolymer shell were developed for background-free near-infrared imaging of cancer cells. The particles showed excellent colloidal stability in buffers and culture media. After conjugation with a cyclic RGD peptide they selectively targeted integrin αvβ3 receptors on glioblastoma cells with high internalization efficacy. Electronic supplementary information (ESI) available: Materials and methods, colloidal stability studies and cell viability studies. See DOI: 10.1039/c4nr02776k

  18. Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT.

    PubMed

    Xu, Shoufang; Lu, Hongzhi

    2016-11-15

    A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as "functional monomer" for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as "functional monomer", exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6-95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors.

  19. THC-MP: High performance numerical simulation of reactive transport and multiphase flow in porous media

    NASA Astrophysics Data System (ADS)

    Wei, Xiaohui; Li, Weishan; Tian, Hailong; Li, Hongliang; Xu, Haixiao; Xu, Tianfu

    2015-07-01

    The numerical simulation of multiphase flow and reactive transport in the porous media on complex subsurface problem is a computationally intensive application. To meet the increasingly computational requirements, this paper presents a parallel computing method and architecture. Derived from TOUGHREACT that is a well-established code for simulating subsurface multi-phase flow and reactive transport problems, we developed a high performance computing THC-MP based on massive parallel computer, which extends greatly on the computational capability for the original code. The domain decomposition method was applied to the coupled numerical computing procedure in the THC-MP. We designed the distributed data structure, implemented the data initialization and exchange between the computing nodes and the core solving module using the hybrid parallel iterative and direct solver. Numerical accuracy of the THC-MP was verified through a CO2 injection-induced reactive transport problem by comparing the results obtained from the parallel computing and sequential computing (original code). Execution efficiency and code scalability were examined through field scale carbon sequestration applications on the multicore cluster. The results demonstrate successfully the enhanced performance using the THC-MP on parallel computing facilities.

  20. A High Contrast Tri-state Fluorescent Switch: Properties and Applications.

    PubMed

    Su, Xing; Wang, Yi; Fang, Xiaofeng; Zhang, Yu-Mo; Zhang, Ting; Li, Minjie; Liu, Yifei; Lin, Tingting; Zhang, Sean Xiao-An

    2016-11-22

    A high contrast tri-state fluorescent switch (FSPTPE) with both emission color change and on/off switching is achieved in a single molecular system by fusing the aggregation-induced emissive tetraphenylethene (TPE) with a molecular switch of spiropyran (SP). In contrast to most of the reported solid-state fluorescent switches, FSPTPE only exists in the amorphous phase in the ring-closed form owing to its highly asymmetric molecular geometry and weak intermolecular interactions, which leads to its grinding-inert stable cyan emission in the solid state. Such an amorphous phase facilitates the fast response of FSPTPE to acidic gases and induces the structural transition from the ring-closed form to ring-open form, accompanied with the "Off" state of the fluorescence. The structural transition leads to a planar molecular conformation and high dipole moment, which further results in strong intermolecular interactions and good crystallinity, so when the acid is added together with a solvent, both the ring-opening reaction and re-crystallization can be triggered to result in an orange emissive state. The reversible control between any two of the three states (cyan/orange/dark) can be achieved with acid/base or mechanical force/solvent treatment. Because of the stable initial state and high color contrast (Δλ=120 nm for cyan/orange switch, dark state ΦF <0.01 %), the fluorescent switch is very promising for applications such as displays, chemical or mechanical sensing, and anti-counterfeiting.

  1. Planar laser-induced fluorescence measurements of high-enthalpy free jet flow with nitric oxide

    NASA Technical Reports Server (NTRS)

    Palmer, Jennifer L.; Mcmillin, Brian K.; Hanson, Ronald K.

    1992-01-01

    Planar laser-induced fluorescence (PLIF) measurements of property fields in a high-enthalpy, supersonic, underexpanded free jet generated in a reflection-type shock tunnel are reported. PLIF images showing velocity and temperature sensitivity are presented. The inferred radial velocity and relative rotational temperature fields are found to be in agreement with those predicted by a numerical simulation of the flowfield using the method of characteristics.

  2. Highly Fluorescent and Photostable Polymeric Nanofibers as Scaffolds for Cell Interfacing and Long-Term Tracking.

    PubMed

    Diao, Hua Jia; Wang, Kai; Long, Hong Yan; Wang, Mingfeng; Chew, Sing Yan

    2016-03-09

    Highly fluorescent polymeric nanofibers fabricated via electrospinning of PCL-DPP-PCL (photostable polycaprolactones-di(thiophene-2-yl)-diketopyrrolopyrrole-photostable polycaprolactones) and commercial PCL mixture show superior photostability and cytocompatibility for long-term tracking of cell-substrate interaction. As a proof of concept, these PCL-DPP-PCL nanofibers enable clear visualization of intricate cell-substrate interactions such as oligodendrocyte myelination.

  3. Highly sensitive ratiometric fluorescent chemosensor for silver ion and silver nanoparticles in aqueous solution.

    PubMed

    Jang, Sujung; Thirupathi, Ponnaboina; Neupane, Lok Nath; Seong, Junho; Lee, Hyunsook; Lee, Wan In; Lee, Keun-Hyeung

    2012-09-21

    A pyrene derivative chemosensor (Pyr-WH) based on a dipeptide shows a highly sensitive ratiometric response to Ag(I) as well as silver nanoparticles in aqueous solution at physiological pH. Pyr-WH penetrated live HeLa cells and exhibits a ratiometric response to intracellular Ag(I). The binding mode of Pyr-WH with Ag(I) was characterized based on fluorescence changes in different pH, NMR, and ESI mass spectrometer experiments.

  4. High affinity truncated DNA aptamers for the development of fluorescence based progesterone biosensors.

    PubMed

    Alhadrami, Hani A; Chinnappan, Raja; Eissa, Shimaa; Rahamn, Anas Abdel; Zourob, Mohammed

    2017-02-24

    Aptamers have shown a number of potential applications in sensing and therapeutic due to the high affinity and specificity towards their target molecules. Not all the nucleotides in the full length aptamers are involved in the binding with their targets. The non-binding domain of the aptamer may affect the binding affinity of the aptamer-target complex. Mapping the aptamer binding region could increase the affinity and the specificity. In this paper, we designed aptamer-based fluorescence sensors from a truncated progesterone (P4) aptamer. Then, fluorescein and quencher labelled aptamer complementary oligonucleotide sequences were hybridized to the truncated aptamer at different sites to form duplex structures. We used fluorescence-quencher pair displacement assay upon progesterone binding for the determination of P4. One of the truncated sequences has shown high binding affinity with 16 fold increase in the dissociation constant, Kd (2.1 nM) compared to the original aptamer. The aptasensor was highly selective for P4 against similar compounds such as 17-β estradiol, bisphenol-A and vitamin D. The sensor has been applied for the detection of P4 in spiked tap water and in urine samples showing good recovery. This new developed aptamer-based fluorescence biosensor can be applied in food, pharmaceutical, and clinical industries.

  5. Determination of Yttrium in High Density Silicon Nitride by Emission and X-Ray Fluorescence Spectroscopy.

    DTIC Science & Technology

    1981-08-01

    AD-AI07 596 ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA F/S 7/4 DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMI-ETCIU...AUG Al B H STRAUSS. UNCLASSIFIED AMMRC-TR-Al-39 N AMMRC TR 81-39 A ~LEVEL ’ t’- .- DETERMINATION OF YTTRIUM IN 1 HIGH DENSITY SILICON NITRIDE BY...DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMISSION AND X-RAY Final Report FLUORESCENCE SPECTROSCOPY 6 PERFORMING ORG. REPORT NUMBER 7. AUTHOR

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

    SciTech Connect

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

    2014-06-09

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

  7. A ratiometric fluorescent nanoprobe based on terbium functionalized carbon dots for highly sensitive detection of an anthrax biomarker.

    PubMed

    Chen, Hao; Xie, Yujie; Kirillov, Alexander M; Liu, Liangliang; Yu, Minghui; Liu, Weisheng; Tang, Yu

    2015-03-25

    A ratiometric fluorescent nanoprobe based on terbium functionalized carbon dots (CDs) was designed to detect dipicolinic acid (DPA) as an anthrax biomarker with high selectivity and sensitivity. CDs were generated by one-step synthesis using an ethylenediaminetetraacetic acid precursor, and served as a scaffold for coordination with Tb(3+) and a fluorescence reference.

  8. 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.

  9. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  10. Development of a standing-wave fluorescence microscope with high nodal plane flatness.

    PubMed

    Freimann, R; Pentz, S; Hörler, H

    1997-09-01

    This article reports about the development and application of a standing-wave fluorescence microscope (SWFM) with high nodal plane flatness. As opposed to the uniform excitation field in conventional fluorescence microscopes as SWFM uses a standing-wave pattern of laser light. This pattern consists of alternating planar nodes and antinodes. By shifting it along the axis of the microscope a set of different fluorescent structures can be distinguished. Their axial separation may just be a fraction of a wavelength so that an SWFM allows distinction of structures which would appear axially unresolved in a conventional or confocal fluorescence microscope. An SWFM is most powerful when the axial extension of the specimen is comparable to the wavelength of light. Otherwise several planes are illuminated simultaneously and their separation is hardly feasible. The objective of this work was to develop a new SWFM instrument which allows standing-wave fluorescence microscopy with controlled high nodal plane flatness. Earlier SWFMs did not allow such a controlled flatness, which impeded image interpretation and processing. Another design goal was to build a compact, easy-to-use instrument to foster a more widespread use of this new technique. The instrument developed uses a green-emitting helium-neon laser as the light source, a piezoelectric movable beamsplitter to generate two mutually coherent laser beams of variable relative phase and two single-mode fibres to transmit these beams to the microscope. Each beam is passed on to the specimen by a planoconvex lens and an objective lens. The only reflective surface whose residual curvature could cause wavefront deformations is a dichroic beamsplitter. Nodal plane flatness is controlled via interference fringes by a procedure which is similar to the interferometric test of optical surfaces. The performance of the instrument was tested using dried and fluorescently labelled cardiac muscle cells of rats. The SWFM enabled the

  11. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  12. Biofunctionalized magnetic nanoparticles for high-sensitivity immunomagnetic detection of human C-reactive protein

    NASA Astrophysics Data System (ADS)

    Horng, H. E.; Yang, S. Y.; Hong, Chin-Yih; Liu, C. M.; Tsai, P. S.; Yang, H. C.; Wu, C. C.

    2006-06-01

    In this work, we developed immunomagnetic detection techniques for detecting human C-reactive protein (CRP). To enhance the technique's sensitivity to human CRP, biofunctionalized magnetic nanoparticles were used as markers, and a superconductive quantum interference device gradiometer system was adapted to measure the saturated magnetization of magnetically labeled CRP-anti-CRP immune complexes. Sensitivity for human CRP was found to be as high as 1ng in 0.1ml, i.e., 10ng/ml in concentration. This sensitivity is much higher than that of conventional enzyme linked immunosorbent assay by one order of magnitude.

  13. Fluidizable zinc titanate materials with high chemical reactivity and attrition resistance

    DOEpatents

    Gupta, R.P.; Gangwal, S.K.; Jain, S.C.

    1993-10-19

    Highly durable and chemically reactive zinc titanate materials are prepared in a particle size range of 50 to 400 [mu]m suitable for a fluidized-bed reactor for removing reduced sulfur species in a gaseous form by granulating a mixture of fine zinc oxide and titanium oxide with inorganic and organic binders and by optional additions of small amounts of activators such as CoO and MoO[sub 3]; and then indurating it at 800 to 900 C for a time sufficient to produce attrition-resistant granules.

  14. Fluidizable zinc titanate materials with high chemical reactivity and attrition resistance

    DOEpatents

    Gupta, Raghubir P.; Gangwal, Santosh K.; Jain, Suresh C.

    1993-01-01

    Highly durable and chemically reactive zinc titanate materials are prepared in a particle size range of 50 to 400 .mu.m suitable for a fluidized-bed reactor for removing reduced sulfur species in a gaseous form by granulating a mixture of fine zinc oxide and titanium oxide with inorganic and organic binders and by optional additions of small amounts of activators such as CoO and MoO.sub.3 ; and then indurating it at 800.degree. to 900.degree. C. for a time sufficient to produce attrition-resistant granules.

  15. High-fidelity hydrophilic probe for two-photon fluorescence lysosomal imaging.

    PubMed

    Wang, Xuhua; Nguyen, Dao M; Yanez, Ciceron O; Rodriguez, Luis; Ahn, Hyo-Yang; Bondar, Mykhailo V; Belfield, Kevin D

    2010-09-08

    The synthesis and characterization of a novel two-photon-absorbing fluorene derivative, LT1, selective for the lysosomes of HCT 116 cancer cells, is reported. Linear and nonlinear photophysical and photochemical properties of the probe were investigated to evaluate the potential of the probe for two-photon fluorescence microscopy (2PFM) lysosomal imaging. The cytotoxicity of the probe was investigated to evaluate the potential of using this probe for live two-photon fluorescence biological imaging applications. Colocalization studies of the probe with commercial Lysotracker Red in HCT 116 cells demonstrated the specific localization of the probe in the lysosomes with an extremely high colocalization coefficient (0.96). A figure of merit was introduced to allow comparison between probes. LT1 has a number of properties that far exceed those of commercial lysotracker probes, including higher two-photon absorption cross sections, good fluorescence quantum yield, and, importantly, high photostability, all resulting in a superior figure of merit. 2PFM was used to demonstrate lysosomal tracking with LT1.

  16. High sensitivity automated multiplexed immunoassays using photonic crystal enhanced fluorescence microfluidic system.

    PubMed

    Tan, Yafang; Tang, Tiantian; Xu, Haisheng; Zhu, Chenqi; Cunningham, Brian T

    2015-11-15

    We demonstrate a platform that integrates photonic crystal enhanced fluorescence (PCEF) detection of a surface-based microspot fluorescent assay with a microfluidic cartridge to achieve simultaneous goals of high analytic sensitivity (single digit pg/mL), high selectivity, low sample volume, and assay automation. The PC surface, designed to provide optical resonances for the excitation wavelength and emission wavelength of Cyanines 5 (Cy5), was used to amplify the fluorescence signal intensity measured from a multiplexed biomarker microarray. The assay system is comprised of a plastic microfluidic cartridge for holding the PC and an assay automation system that provides a leak-free fluid interface during introduction of a sequence of fluids under computer control. Through the use of the assay automation system and the PC embedded within the microfluidic cartridge, we demonstrate pg/mL-level limits of detection by performing representative biomarker assays for interleukin 3 (IL3) and Tumor Necrosis Factor (TNF-α). The results are consistent with limits of detection achieved without the use of the microfluidic device with the exception that coefficients of variability from spot-to-spot are substantially lower than those obtained by performing assays with manual manipulation of assay liquids. The system's capabilities are compatible with the goal of diagnostic instruments for point-of-care settings.

  17. High Sensitivity Automated Multiplexed Immunoassays Using Photonic Crystal Enhanced Fluorescence Microfluidic System

    PubMed Central

    Tan, Yafang; Tang, Tiantian; Xu, Haisheng; Zhu, Chenqi; Cunningham, Brian T.

    2015-01-01

    We demonstrate a platform that integrates photonic crystal enhanced fluorescence (PCEF) detection of a surface-based microspot fluorescent assay with a microfluidic cartridge to achieve simultaneous goals of high analytic sensitivity (single digit pg/mL), high selectivity, low sample volume, and assay automation. The PC surface, designed to provide optical resonances for the excitation wavelength and emission wavelength of Cyanines 5 (Cy5), was used to amplify the fluorescence signal intensity measured from a multiplexed biomarker microarray. The assay system is comprised of a plastic microfluidic cartridge for holding the PC and an assay automation system that provides a leak-free fluid interface during introduction of a sequence of fluids under computer control. Through the use of the assay automation system and the PC embedded within the microfluidic cartridge, we demonstrate pg/mL-level limits of detection by performing representative biomarker assays for interleukin 3 (IL3) and Tumor Necrosis Factor (TNF-α). The results are consistent with limits of detection achieved without the use of the microfluidic device with the exception that coefficients of variability from spot-to-spot are substantially lower than those obtained by performing assays with manual manipulation of assay liquids. The system’s capabilities are compatible with the goal of diagnostic instruments for point-of-care settings. PMID:26043313

  18. A highly Selective Fluorescent Chemosensor for Zn(2+) Based on the Rhodamine Derivative Incorporating Coumarin Group.

    PubMed

    Wang, Kun-Peng; Jin, Zhi-Hui; Shang, Hui-Shi; Lv, Cheng-Dong; Zhang, Qi; Chen, Shaojin; Hu, Zhi-Qiang

    2017-03-01

    A coumarin-appended rhodamine derivative was prepared by reacting rhodamine hydrazide and coumarin-3-carboxylic acid, which fluorescence sensing behavior toward Zn(2+) against other metal ions was investigated in CH3CN. Significantly, the rodamine-coumarin derivative exhibited highly selective and sensitive recognition toward Zn(2+) with a limit of detection (LOD) down to 10(-9) M. Upon addition of Zn(2+), remarkable fluorescent intensities enhanced and also clear color changed from colorless to pink. The Job's plot indicated the formation of 1:1 complex between the rhodamine-coumarin derivative and Zn(2+). The presence of common coexisting alkali, alkaline earth, and transition metal ions showed small or no interference with the detection of Zn(2+). The conjugate dye could be used for "naked-eye" detection of Zn(2+).

  19. Highly selective fluorescent recognition of Zn2+ based on naphthalene macrocyclic derivative.

    PubMed

    Azadbakht, Reza; Parviz, Maisam; Tamari, Esmail; Keypour, Hassan; Golbedaghi, Reza

    2011-11-01

    A new macrocyclic chemosensor containing two naphthalene fluorophores has been synthesized. The fluorescent properties of this receptor has been studied in the presence of various metal ions such as Na(+), Ag(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+). When increasing concentrations of Zn(2+) ions were introduced, the emission of L was drastically increased (EFE = 4.34). This special change was not observed when other metal ions were used; such highly selective fluorescent response indicates that this receptor can easily discriminate Zn(2+) ions from other similar species. Model calculations at DFT level further suggest the possible interaction mode, and relatively steric position between the host and guest also influence the optical response.

  20. Highly selective, sensitive and fast-responsive fluorescent sensor for Hg2 +

    NASA Astrophysics Data System (ADS)

    Niu, Qingfen; Wu, Xingxing; Li, Tianduo; Cui, Yuezhi; Zhang, Shanshan; Li, Xiaoyan

    2016-06-01

    A phenylamine-oligothiophene-based fluorescent sensor 2TBEA was reported. This sensor exhibited highly selective, sensitive and rapid detection of Hg2 + ion in THF/H2O (7/3, v/v) solution through fluorescence quenching. The detection was unaffected by the coexistence of other competitive metal cations including Na+, K+, Ag+, Ca2 +, Fe3 +, Al3 +, Co2 +, Cu2 +, Ni2 +, Zn2 +, Pb2 +, Cd2 +, Fe2 + and Cr3 +. A1:1 binding ratio for 2TBEA - Hg2 + was demonstrated by Job's plot and mole-ratio curves. The coordination process was chemically reversible with EDTA. The detection limit was evaluated to be as low as 6.164 × 10- 8 M.

  1. Bodilisant-a novel fluorescent, highly affine histamine h3 receptor ligand.

    PubMed

    Tomasch, Miriam; Schwed, J Stephan; Paulke, Alexander; Stark, Holger

    2013-02-14

    A piperidine-based lead structure for the human histamine H3 receptor (hH3R) was coupled with the BODIPY fluorophore and resulted in a strong green fluorescent (quantum yield, 0.92) hH3R ligand with affinity in the nanomolar concentration range (K i hH3R = 6.51 ± 3.31 nM), named Bodilisant. Screening for affinities at histamine and dopamine receptor subtypes showed high hH3R preference. Bodilisant was used for visualization of hH3R in hH3R overexpressing HEK-293 cells with fluorescence confocal laser scanning microscopy. In addition, in native human brain tissues, Bodilisant showed clear and displaceable images of labeled hH3R.

  2. Fluorescent Branched RNAs for High-Throughput Analysis of Dbr1 Enzyme Kinetics and Inhibition.

    PubMed

    Katolik, Adam; Clark, Nathaniel E; Tago, Nobuhiro; Montemayor, Eric J; Hart, P John; Damha, Masad J

    2017-01-18

    We have developed fluorescent 2',5' branched RNAs (bRNA) that permit real time monitoring of RNA lariat (intron) debranching enzyme (Dbr1) kinetics. These compounds contain fluorescein (FAM) on the 5' arm of the bRNA that is quenched by a dabcyl moiety on the 2' arm. Dbr1-mediated hydrolysis of the 2',5' linkage induces a large increase in fluorescence, providing a convenient assay for Dbr1 hydrolysis. We show that unlabeled bRNAs with non-native 2',5'-phosphodiester linkages, such as phosphoramidate or phosphorothioate, can inhibit Dbr1-mediated debranching with IC50 values in the low nanomolar range. In addition to measuring kinetic parameters of the debranching enzyme, these probes can be used for high throughput screening (HTS) of chemical libraries with the aim of identifying Dbr1 inhibitors, compounds that may be useful in treating neurodegenerative diseases and retroviral infections.

  3. Highly mobile and reactive state of hydrogen in metal oxide semiconductors at room temperature

    PubMed Central

    Chen, Wan Ping; He, Ke Feng; Wang, Yu; Chan, Helen Lai Wah; Yan, Zijie

    2013-01-01

    Hydrogen in metal oxides usually strongly associates with a neighboring oxygen ion through an O-H bond and thus displays a high stability. Here we report a novel state of hydrogen with unusually high mobility and reactivity in metal oxides at room temperature. We show that freshly doped hydrogen in Nb2O5 and WO3 polycrystals via electrochemical hydrogenation can reduce Cu2+ ions into Cu0 if the polycrystals are immersed in a CuSO4 solution, while this would not happen if the hydrogenated polycrystals have been placed in air for several hours before the immersion. Time-dependent studies of electrochemically hydrogenated rutile single crystals reveal two distinct states of hydrogen: one as protons covalently bonded to oxygen ions, while the other one is highly unstable with a lifetime of just a few hours. Observation of this mobile and reactive state of hydrogen will provide new insight into numerous moderate and low temperature interactions between metal oxides and hydrogen. PMID:24193143

  4. High-pressure ruby and diamond fluorescence - Observations at 0.21 to 0.55 terapascal

    NASA Technical Reports Server (NTRS)

    Xu, J. A.; Mao, H. K.; Bell, P. M.

    1986-01-01

    A diamond-anvil, high-pressure apparatus was used to extend the upper pressure limit of static laboratory experiments. Shifts of the R1 strong fluorescent line of ruby were observed that correspond to static pressures of 0.21 to 0.55 terapascal (2.1 to 5.5 megabars) at 25 C. Sensitive spectroscopic techniques in the pressure range 0.15 to 0.28 terapascal were used to observe ruby and diamond fluorescence separately; these two fluorescent emissions overlap strongly at high pressures. At pressures greater than approximately 0.28 terapascal, the diamond fluorescence diminished and the ruby fluorescence reappeared strongly. Pressure was determined by extrapolation of the calibrated shift of the ruby R1 line.

  5. Observations of fluorescent aerosol-cloud interactions in the free troposphere at the High-Altitude Research Station Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Crawford, I.; Lloyd, G.; Herrmann, E.; Hoyle, C. R.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

    2016-02-01

    The fluorescent nature of aerosol at a high-altitude Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultraviolet - light-induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high-altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor increase in the fluorescent aerosol fraction during in-cloud cases compared to out-of-cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27 ± 0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosols were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1 ± 0.4 L-1. Given the low concentration of this cluster and the typically low ice-active fraction of studied PBAP (e.g. pseudomonas syringae), we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

  6. Fluorescent trimethyl-substituted naphthyridine as a label-free signal reporter for one-step and highly sensitive fluorescent detection of DNA in serum samples.

    PubMed

    Wang, Jiamian; Wang, Xiuyun; Wu, Shuo; Che, Ruping; Luo, Pinchen; Meng, Changgong

    2017-01-15

    A facile label-free sensing method is developed for the one-step and highly sensitive fluorescent detection of DNA, which couples the specific C-C mismatch bonding and fluorescent quenching property of a trimethyl-substituted naphthyridine dye (ATMND) with the exonuclease III (Exo III) assisted cascade target recycling amplification strategy. In the absence of target DNA, the DNA hairpin probe with a C-C mismatch in the stem and more than 4 bases overhung at the 3' terminus could entrap and quench the fluorescence of ATMND and resist the digestion of Exo III, thus showing a low fluorescence background. In the presence of the target, however, the hybridization event between the two protruding segments and the target triggers the digestion reaction of Exo III, recycles the initial target, and simultaneously releases both the secondary target analogue and the ATMND caged in the stem. The released initial and secondary targets take part in another cycle of digestion, thus leading to the release of a huge amount of free ATMND for signal transducing. Based on the fluorescence recovery, the as-proposed label-free fluorescent sensing strategy shows very good analytical performances towards DNA detection, such as a wide linear range from 10pM to 1μM, a low limit of detection of 6pM, good selectivity, and a facile one-step operation at room temperature. Practical sample analysis in serum samples indicates the method has good precision and accuracy, which may thus have application potentials for point-of-care screening of DNA in complex clinical and environmental samples.

  7. High on-treatment platelet reactivity in transcatheter aortic valve implantation patients.

    PubMed

    Polzin, Amin; Schleicher, Mathias; Seidel, Holger; Scharf, Rüdiger E; Merx, Marc W; Kelm, Malte; Zeus, Tobias

    2015-03-15

    Dual antiplatelet therapy (DAPT) is recommended early after transcatheter aortic valve implantation (TAVI) procedure at the moment despite the lack of evidence. Two small randomized trials failed to demonstrate DAPT to be superior to aspirin alone in TAVI patients. However, it is known that there are substantial response variabilities to antiplatelet medication. We aimed to investigate high on-treatment platelet reactivity (HTPR), low on-treatment platelet reactivity (LTPR) to clopidogrel as well as HTPR to aspirin in patients undergoing TAVI procedure. We analyzed data of 140 TAVI patients in a real world observational study. Platelet function assays (clopidogrel-vasodilator-stimulated protein phosphorylation assay; aspirin-light-transmission aggregometry) have been performed during hospital course. Clinical complications were investigated during 30 days follow-up and defined using the valve academic research consortium standardized criteria. HTPR to clopidogrel occurred in 87 (62%) patients and LTPR in 9 (6.4%) patients. Aspirin antiplatelet effects were insufficient in 25 (18%) patients. Clinical complications were observed in 35 (25%) patients. Ischemic events occurred in 6 (4%), bleeding complications in 28 (20%) patients. There were no differences regarding the incidence of HTPR/LTPR in patients with overall complications, ischemic events or bleeding events. HTPR to clopidogrel is very frequent in TAVI patients. However bleeding complications are frequent and ischemic events are rare. Therefore, future clinical trials investigating the optimal antithrombotic regiment in TAVI patients should consider this high incidence of HTPR to clopidogrel and monitor clopidogrel antiplatelet effects carefully.

  8. Brain reactivity differentiates subjects with high and low dream recall frequencies during both sleep and wakefulness.

    PubMed

    Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Ruby, Perrine

    2014-05-01

    The neurophysiological correlates of dreaming remain unclear. According to the "arousal-retrieval" model, dream encoding depends on intrasleep wakefulness. Consistent with this model, subjects with high and low dream recall frequency (DRF) report differences in intrasleep awakenings. This suggests a possible neurophysiological trait difference between the 2 groups. To test this hypothesis, we compared the brain reactivity (evoked potentials) of subjects with high (HR, N = 18) and low (LR, N = 18) DRF during wakefulness and sleep. During data acquisition, the subjects were presented with sounds to be ignored (first names randomly presented among pure tones) while they were watching a silent movie or sleeping. Brain responses to first names dramatically differed between the 2 groups during both sleep and wakefulness. During wakefulness, the attention-orienting brain response (P3a) and a late parietal response were larger in HR than in LR. During sleep, we also observed between-group differences at the latency of the P3a during N2 and at later latencies during all sleep stages. Our results demonstrate differences in the brain reactivity of HR and LR during both sleep and wakefulness. These results suggest that the ability to recall dreaming is associated with a particular cerebral functional organization, regardless of the state of vigilance.

  9. Dynamic Solvent Control of a Reaction in Ionic Deep Eutectic Solvents: Time-Resolved Fluorescence Measurements of Reactive and Nonreactive Dynamics in (Choline Chloride + Urea) Melts.

    PubMed

    Das, Anuradha; Biswas, Ranjit

    2015-08-06

    Dynamic fluorescence anisotropy and Stokes shift measurements of [f choline chloride + (1 - f) urea)] deep eutectic solvents at f = 0.33 and 0.40 have been carried out using a dipolar solute, coumarin 153 (C153), in the temperature range 298 ≤ T ≤ 333 K. Subsequently, measured time-dependent solvent response is utilized to investigate the dynamic solvent control on the measured rates of photoexcited intramolecular charge transfer (ICT) reactions of two molecules, 4-(1-azetidinyl)benzonitrile (P4C) and 4-(1-pyrrolidinyl)benzonitrile (P5C), occurring in these media. Measured average reaction time scales (⟨τ(rxn)⟩) exhibit the following dependence on average solvation times scales (⟨τ(s)⟩): ⟨τ(rxn)⟩ ∝ ⟨τ(s)⟩(α) with α = 0.5 and 0.35 for P4C and P5C, respectively. Such a strong dynamic solvent control of ⟨τ(rxn)⟩, particularly for P4C, is different from earlier observations with these ICT molecules in conventional molecular solvents. Excitation wavelength-dependent fluorescence emissions of C153 and trans-2-[4-(dimethylamino)styryl]-benzothiazole (DMASBT), which differ widely in average fluorescence lifetimes (⟨τ(life)⟩), suggest the presence of substantial spatial heterogeneity in these systems. Dynamic heterogeneity is reflected via the following fractional viscosity (η) dependences of ⟨τ(s)⟩ and ⟨τ(r)⟩ (⟨τ(r)⟩ being solute's average rotation time): ⟨τx⟩ ∝ (η/T)(p) with 0.7 ≤ p ≤ 0.9. Different correlations between ⟨τ(s)⟩ and ⟨τ(r)⟩ emerge at different temperature regimes, indicating variable frictional coupling at low and high temperatures. Estimated dynamic Stokes shifts in these media vary between ∼1200 and ∼1600 cm(-1), more than 50% of which possess a time scale much faster than the temporal resolution (∼75 ps) employed in these measurements. Estimated activation energy for η is closer to that for ⟨τ(r)⟩ than that for ⟨τ(s)⟩, suggesting ⟨τ(s)⟩ being more decoupled

  10. High-Resolution Solid Modeling of Biological Samples Imaged with 3D Fluorescence Microscopy

    PubMed Central

    Ferko, Michael C.; Patterson, Brian W.; Butler, Peter J.

    2011-01-01

    Optical-sectioning, digital fluorescence microscopy provides images representing temporally- and spatially-resolved molecular-scale details of the substructures of living cells. To render such images into solid models for further computational analyses, we have developed an integrated system of image acquisition, processing, and rendering, which includes a new empirical technique to correct for axial distortions inherent in fluorescence microscopy due to refractive index mismatches between microscope objective immersion medium, coverslip glass, and water. This system takes advantage of the capabilities of ultra-high numerical aperture objectives (e.g. total internal reflection fluorescence microscopy) and enables faithful three-dimensional rendering of living cells into solid models amenable to further computational analysis. An example of solid modeling of bovine aortic endothelial cells and their nuclei is presented. Since many cellular level events are temporally and spatially confined, such integrated image acquisition, processing, rendering, and computational analysis, will enable, in silico, the generation of new computational models for cell mechanics and signaling. PMID:16758474

  11. Fluorescent probe for high-throughput screening of membrane protein expression

    PubMed Central

    Backmark, A E; Olivier, N; Snijder, A; Gordon, E; Dekker, N; Ferguson, A D

    2013-01-01

    Screening of protein variants requires specific detection methods to assay protein levels and stability in crude mixtures. Many strategies apply fluorescence-detection size-exclusion chromatography (FSEC) using green fluorescent protein (GFP) fusion proteins to qualitatively monitor expression, stability, and monodispersity. However, GFP fusion proteins have several important disadvantages; including false-positives, protein aggregation after proteolytic removal of GFP, and reductions in protein yields without the GFP fusion. Here we describe a FSEC screening strategy based on a fluorescent multivalent NTA probe that interacts with polyhistidine-tags on target proteins. This method overcomes the limitations of GFP fusion proteins, and can be used to rank protein production based on qualitative and quantitative parameters. Domain boundaries of the human G-protein coupled adenosine A2a receptor were readily identified from crude detergent-extracts of a library of construct variants transiently produced in suspension-adapted HEK293-6E cells. Well expressing clones of MraY, an important bacterial infection target, could be identified from a library of 24 orthologs. This probe provides a highly sensitive tool to detect target proteins to expression levels down to 0.02 mg/L in crude lysate, and requires minimal amounts of cell culture. PMID:23776061

  12. Miniaturized selective plane illumination microscopy for high-contrast in vivo fluorescence imaging.

    PubMed

    Engelbrecht, Christoph J; Voigt, Fabian; Helmchen, Fritjof

    2010-05-01

    Light-sheet-based fluorescence imaging techniques rely on simultaneous excitation of a single optical plane and thus permit high-contrast optically sectioned imaging of extended tissue samples. Here, we introduce a miniaturized fiber-optic implementation of a selective plane-illumination microscope (miniSPIM). The excitation light was delivered through a single-mode optical fiber, and a light-sheet was created with a cylindrical gradient-index lens and a right-angle microprism. Fluorescence emission was collected orthogonally to the light-sheet through a gradient-index lens assembly and a coherent fiber bundle. The end face of the fiber bundle was imaged onto a charge-coupled device camera. The spatial resolutions of the miniSPIM were 3.2 microm laterally and 5.1 microm axially. Images of fluorescent beads and neurons in mouse neocortex exhibited superior axial resolution and contrast in the miniSPIM-mode compared to images recorded in epi-illumination mode. The miniSPIM may thus enable novel in vivo imaging approaches.

  13. Fluorescence polarization assays in high-throughput screening and drug discovery: a review

    NASA Astrophysics Data System (ADS)

    Hall, Matthew D.; Yasgar, Adam; Peryea, Tyler; Braisted, John C.; Jadhav, Ajit; Simeonov, Anton; Coussens, Nathan P.

    2016-06-01

    The sensitivity of fluorescence polarization (FP) and fluorescence anisotropy (FA) to molecular weight changes has enabled the interrogation of diverse biological mechanisms, ranging from molecular interactions to enzymatic activity. Assays based on FP/FA technology have been widely utilized in high-throughput screening (HTS) and drug discovery due to the homogenous format, robust performance and relative insensitivity to some types of interferences, such as inner filter effects. Advancements in assay design, fluorescent probes, and technology have enabled the application of FP assays to increasingly complex biological processes. Herein we discuss different types of FP/FA assays developed for HTS, with examples to emphasize the diversity of applicable targets. Furthermore, trends in target and fluorophore selection, as well as assay type and format, are examined using annotated HTS assays within the PubChem database. Finally, practical considerations for the successful development and implementation of FP/FA assays for HTS are provided based on experience at our center and examples from the literature, including strategies for flagging interference compounds among a list of hits.

  14. Two-photon fluorescence microscopy signal formation in highly scattering media: theoretical and numerical simulation

    SciTech Connect

    Sergeeva, Ekaterina A; Katichev, A R; Kirillin, M Yu

    2011-01-24

    Using the radiative transfer theory and Monte Carlo simulations, we analyse the effect of scattering in a medium and of the size of the detector pinhole on the formation of the fluorescent signal in standard two-photon fluorescence microscopy (TPFM) systems. The theoretical analysis is based on a small-angle diffusion approximation of the radiative transfer equation, adapted to calculate the propagation of focused infrared radiation in media similar to the biological tissues in their optical properties. The accuracy of the model is evaluated by comparing the calculated excitation intensity in a highly scattering medium with the results of Monte Carlo simulations. To simulate a tightly focused Gaussian beam by the Monte Carlo method, the so called 'ray-optics' approach that correctly takes into account the finite size and shape of the beam waist is applied. It is shown that in the combined confocal and two-photon scanning microscopy systems not equipped with an external 'nondescanned' detector, the scattering significantly affects both the nonlinear excitation efficiency in the medium and the fluorescence collection efficiency of the system. In such systems, the rate of the useful TPFM signal in-depth decay is 1.5 - 2 times higher than in systems equipped with a 'nondescanned' detector. (application of lasers and laser-optical methods in life sciences)

  15. Fluorescent water-soluble organic aerosols in the High Arctic atmosphere

    PubMed Central

    Fu, Pingqing; Kawamura, Kimitaka; Chen, Jing; Qin, Mingyue; Ren, Lujie; Sun, Yele; Wang, Zifa; Barrie, Leonard A.; Tachibana, Eri; Ding, Aijun; Yamashita, Youhei

    2015-01-01

    Organic aerosols are ubiquitous in the earth’s atmosphere. They have been extensively studied in urban, rural and marine environments. However, little is known about the fluorescence properties of water-soluble organic carbon (WSOC) or their transport to and distribution in the polar regions. Here, we present evidence that fluorescent WSOC is a substantial component of High Arctic aerosols. The ratios of fluorescence intensity of protein-like peak to humic-like peak generally increased from dark winter to early summer, indicating an enhanced contribution of protein-like organics from the ocean to Arctic aerosols after the polar sunrise. Such a seasonal pattern is in agreement with an increase of stable carbon isotope ratios of total carbon (δ13CTC) from −26.8‰ to −22.5‰. Our results suggest that Arctic aerosols are derived from a combination of the long-range transport of terrestrial organics and local sea-to-air emission of marine organics, with an estimated contribution from the latter of 8.7–77% (mean 45%). PMID:25920042

  16. Reactivity Accountability Attributed to Reflector Poisons in the High Flux Isotope Reactor

    SciTech Connect

    Chandler, David; Maldonado, G Ivan; Primm, Trent

    2009-12-01

    The objective of this study is to develop a methodology to predict the reactivity impact as a function of outage time between cycles of 3He, 6Li, and other poisons in the High Flux Isotope Reactor s (HFIR) beryllium reflector. The reactivity worth at startup of the HFIR has been incorrectly predicted in the past after the reactor has been shut-down for long periods of time. The incorrect prediction was postulated to be due to the erroneous calculation of 3He buildup in the beryllium reflector. It is necessary to develop a better estimate of the start-of-cycle symmetric critical control element positions since if the estimated and actual symmetrical critical control element positions differ by more than $1.55 in reactivity (approximately one-half inch in control element startup position), HFIR is to be shutdown and a technical evaluation is performed to resolve the discrepancy prior to restart. 3He is generated and depleted during operation, but during an outage, the depletion of 3He ceases because it is a stable isotope. 3He is born from the radioactive decay of tritium, and thus the concentration of 3He increases during shutdown. SCALE, specifically the TRITON and CSAS5 control modules including the KENO V.A, COUPLE, and ORIGEN functional modules were utilized in this study. An equation relating the down time (td) to the change in symmetric control element position was generated and validated against measurements for approximately 40 HFIR operating cycles. The newly-derived correlation was shown to improve accuracy of predictions for long periods of down time.

  17. Smartphone-Based Fluorescent Diagnostic System for Highly Pathogenic H5N1 Viruses.

    PubMed

    Yeo, Seon-Ju; Choi, Kyunghan; Cuc, Bui Thi; Hong, Nguyen Ngoc; Bao, Duong Tuan; Ngoc, Nguyen Minh; Le, Mai Quynh; Hang, Nguyen Le Khanh; Thach, Nguyen Co; Mallik, Shyam Kumar; Kim, Hak Sung; Chong, Chom-Kyu; Choi, Hak Soo; Sung, Haan Woo; Yu, Kyoungsik; Park, Hyun

    2016-01-01

    Field diagnostic tools for avian influenza (AI) are indispensable for the prevention and controlled management of highly pathogenic AI-related diseases. More accurate, faster and networked on-site monitoring is demanded to detect such AI viruses with high sensitivity as well as to maintain up-to-date information about their geographical transmission. In this work, we assessed the clinical and field-level performance of a smartphone-based fluorescent diagnostic device with an efficient reflective light collection module using a coumarin-derived dendrimer-based fluorescent lateral flow immunoassay. By application of an optimized bioconjugate, a smartphone-based diagnostic device had a two-fold higher detectability as compared to that of the table-top fluorescence strip reader for three different AI subtypes (H5N3, H7N1, and H9N2). Additionally, in a clinical study of H5N1-confirmed patients, the smartphone-based diagnostic device showed a sensitivity of 96.55% (28/29) [95% confidence interval (CI): 82.24 to 99.91] and a specificity of 98.55% (68/69) (95% CI: 92.19 to 99.96). The measurement results from the distributed individual smartphones were wirelessly transmitted via short messaging service and collected by a centralized database system for further information processing and data mining. Smartphone-based diagnosis provided highly sensitive measurement results for H5N1 detection within 15 minutes. Because of its high sensitivity, portability and automatic reporting feature, the proposed device will enable agile identification of patients and efficient control of AI dissemination.

  18. Smartphone-Based Fluorescent Diagnostic System for Highly Pathogenic H5N1 Viruses

    PubMed Central

    Yeo, Seon-Ju; Choi, Kyunghan; Cuc, Bui Thi; Hong, Nguyen Ngoc; Bao, Duong Tuan; Ngoc, Nguyen Minh; Le, Mai Quynh; Hang, Nguyen Le Khanh; Thach, Nguyen Co; Mallik, Shyam Kumar; Kim, Hak Sung; Chong, Chom-Kyu; Choi, Hak Soo; Sung, Haan Woo; Yu, Kyoungsik; Park, Hyun

    2016-01-01

    Field diagnostic tools for avian influenza (AI) are indispensable for the prevention and controlled management of highly pathogenic AI-related diseases. More accurate, faster and networked on-site monitoring is demanded to detect such AI viruses with high sensitivity as well as to maintain up-to-date information about their geographical transmission. In this work, we assessed the clinical and field-level performance of a smartphone-based fluorescent diagnostic device with an efficient reflective light collection module using a coumarin-derived dendrimer-based fluorescent lateral flow immunoassay. By application of an optimized bioconjugate, a smartphone-based diagnostic device had a two-fold higher detectability as compared to that of the table-top fluorescence strip reader for three different AI subtypes (H5N3, H7N1, and H9N2). Additionally, in a clinical study of H5N1-confirmed patients, the smartphone-based diagnostic device showed a sensitivity of 96.55% (28/29) [95% confidence interval (CI): 82.24 to 99.91] and a specificity of 98.55% (68/69) (95% CI: 92.19 to 99.96). The measurement results from the distributed individual smartphones were wirelessly transmitted via short messaging service and collected by a centralized database system for further information processing and data mining. Smartphone-based diagnosis provided highly sensitive measurement results for H5N1 detection within 15 minutes. Because of its high sensitivity, portability and automatic reporting feature, the proposed device will enable agile identification of patients and efficient control of AI dissemination. PMID:26877781

  19. Micromolding of a Highly Fluorescent Reticular Coordination Polymer: Solvent-Mediated Reconfigurable Polymerization in a Soft Lithographic Mold

    SciTech Connect

    Y You; H Yang; J Chung; J Kim; Y Jung; S Park

    2011-12-31

    Coordination polymerization of pyridine-based ligands and zinc or silver ions was controlled by soft lithographic micromolding in capillaries. The polymer patterns that are produced are highly fluorescent and supramolecularly structured.

  20. Highly sensitive detection of human papillomavirus type 16 DNA using time-resolved fluorescence microscopy and long lifetime probes

    NASA Astrophysics Data System (ADS)

    Wang, Xue F.; Periasamy, Ammasi; Wodnicki, Pawel; Siadat-Pajouh, M.; Herman, Brian

    1995-04-01

    We have been interested in the role of Human Papillomavirus (HPV) in cervical cancer and its diagnosis; to that end we have been developing microscopic imaging and fluorescent in situ hybridization (FISH) techniques to genotype and quantitate the amount of HPV present at a single cell level in cervical PAP smears. However, we have found that low levels of HPV DNA are difficult to detect accurately because theoretically obtainable sensitivity is never achieved due to nonspecific autofluorescence, fixative induced fluorescence of cells and tissues, and autofluorescence of the optical components in the microscopic system. In addition, the absorption stains used for PAP smears are intensely autofluorescent. Autofluorescence is a rapidly decaying process with lifetimes in the range of 1-100 nsec, whereas phosphorescence and delayed fluorescence have lifetimes in the range of 1 microsecond(s) ec-10 msec. The ability to discriminate between specific fluorescence and autofluorescence in the time-domain has improved the sensitivity of diagnostic test such that they perform comparably to, or even more sensitive than radioisotopic assays. We have developed a novel time-resolved fluorescence microscope to improve the sensitivity of detection of specific molecules of interest in slide based specimens. This time-resolved fluorescence microscope is based on our recently developed fluorescence lifetime imaging microscopy (FILM) in conjunction with the use of long lifetime fluorescent labels. By using fluorescence in situ hybridization and the long lifetime probe (europium), we have demonstrated the utility of this technique for detection of HPV DNA in cervicovaginal cells. Our results indicate that the use of time-resolved fluorescence microscopy and long lifetime probes increases the sensitivity of detection by removing autofluorescence and will thus lead to improved early diagnosis of cervical cancer. Since the highly sensitive detection of DNA in clinical samples using

  1. Cardiovascular Reactivity in Patients With Major Depressive Disorder With High- or Low-Level Depressive Symptoms: A Cross-Sectional Comparison of Cardiovascular Reactivity to Laboratory-Induced Mental Stress.

    PubMed

    Wang, Mei-Yeh; Chiu, Chen-Huan; Lee, Hsin-Chien; Su, Chien-Tien; Tsai, Pei-Shan

    2016-03-01

    Depression increases the risk of adverse cardiac events. Cardiovascular reactivity is defined as the pattern of cardiovascular responses to mental stress. An altered pattern of cardiovascular reactivity is an indicator of subsequent cardiovascular disease. Because depression and adverse cardiac events may have a dose-dependent association, this study examined the differences in cardiovascular reactivity to mental stress between patients with major depressive disorder (MDD) with high depression levels and those with low depression levels. Moreover, autonomic nervous system regulation is a highly plausible biological mechanism for the pattern of cardiovascular reactivity to mental stress. The association between cardiovascular reactivity and parameters of heart rate variability (HRV), an index for quantifying autonomic nervous system activity modulation, was thus examined. This study included 88 patients with MDD. HRV was measured before stress induction. The Stroop Color and Word Test and mirror star-tracing task were used to induce mental stress. We observed no significant association between depressive symptom level and any of the cardiovascular reactivity parameters. Cardiovascular reactivity to mental stress was comparable between patients with MDD with high-level depressive symptoms and those with low-level depressive symptoms. After adjusting for confounding variables, the high-frequency domain of HRV was found to be an independent predictor of the magnitude of heart rate reactivity (β = -.33, p = .002). In conclusion, the magnitude of cardiovascular reactivity may be independent of depression severity in patients with MDD. The autonomic regulation of cardiovascular responses to mental stress primarily influences heart rate reactivity in patients with MDD.

  2. [Development of novel fluorescence-derivatization-HPLC methods enabling highly sensitive and selective analysis of biological compounds].

    PubMed

    Todoroki, Kenichiro

    2011-01-01

    Fluorescence-derivatization-HPLC methods are powerful tools for performing the analysis of bioactive compounds with high sensitivity and selectivity. In this paper, the author reviews the development of the following four types of novel fluorescence-derivatization-HPLC analytical systems: (1) simultaneous HPLC analysis of melatonin and its related compounds through post-column electrochemical demethylation and fluorescence derivatization, (2) HPLC analysis of 5-hydroxyindoles based on fluorescence derivatization by online pre-column photocatalytic oxidation with benzylamine, (3) reagent peak-free HPLC analysis for aliphatic amines and amino acids using F-trap pyrene as a fluorous tag-bound fluorescence derivatization reagent, and (4) reagent peak-free HPLC analysis for carboxylic acids using a fluorous scavenging-derivatization method. The authors have also successfully applied these systems to biological and pharmaceutical analyses.

  3. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans.

    PubMed

    Hawkings, Jon R; Wadham, Jemma L; Tranter, Martyn; Raiswell, Rob; Benning, Liane G; Statham, Peter J; Tedstone, Andrew; Nienow, Peter; Lee, Katherine; Telling, Jon

    2014-05-21

    The Greenland and Antarctic Ice Sheets cover ~ 10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40-2.54 Tg per year in Greenland and 0.06-0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting.

  4. Highly adaptable and sensitive protease assay based on fluorescence resonance energy transfer.

    PubMed

    Zauner, Thomas; Berger-Hoffmann, Renate; Müller, Katrin; Hoffmann, Ralf; Zuchner, Thole

    2011-10-01

    Proteases are widely used in analytical sciences and play a central role in several widespread diseases. Thus, there is an immense need for highly adaptable and sensitive assays for the detection and monitoring of various proteolytic enzymes. We established a simple protease fluorescence resonance energy transfer (pro-FRET) assay for the determination of protease activities, which could in principle be adapted for the detection of all proteases. As proof of principle, we demonstrated the potential of our method using trypsin and enteropeptidase in complex biological mixtures. Briefly, the assay is based on the cleavage of a FRET peptide substrate, which results in a dramatic increase of the donor fluorescence. The assay was highly sensitive and fast for both proteases. The detection limits for trypsin and enteropeptidase in Escherichia coli lysate were 100 and 10 amol, respectively. The improved sensitivity for enteropeptidase was due to the application of an enzyme cascade, which leads to signal amplification. The pro-FRET assay is highly specific as even high concentrations of other proteases did not result in significant background signals. In conclusion, this sensitive and simple assay can be performed in complex biological mixtures and can be easily adapted to act as a versatile tool for the sensitive detection of proteases.

  5. A highly soluble, non-phototoxic, non-fluorescent blebbistatin derivative

    PubMed Central

    Várkuti, Boglárka H.; Képiró, Miklós; Horváth, István Ádám; Végner, László; Ráti, Szilvia; Zsigmond, Áron; Hegyi, György; Lenkei, Zsolt; Varga, Máté; Málnási-Csizmadia, András

    2016-01-01

    Blebbistatin is a commonly used molecular tool for the specific inhibition of various myosin II isoforms both in vitro and in vivo. Despite its popularity, the use of blebbistatin is hindered by its poor water-solubility (below 10 micromolar in aqueous buffer) and blue-light sensitivity, resulting in the photoconversion of the molecule, causing severe cellular phototoxicity in addition to its cytotoxicity. Furthermore, blebbistatin forms insoluble aggregates in water-based media above 10 micromolar with extremely high fluorescence and also high adherence to different types of surfaces, which biases its experimental usage. Here, we report a highly soluble (440 micromolar in aqueous buffer), non-fluorescent and photostable C15 amino-substituted derivative of blebbistatin, called para-aminoblebbistatin. Importantly, it is neither photo- nor cytotoxic, as demonstrated on HeLa cells and zebrafish embryos. Additionally, para-aminoblebbistatin bears similar myosin II inhibitory properties to blebbistatin or para-nitroblebbistatin (not to be confused with the C7 substituted nitroblebbistatin), tested on rabbit skeletal muscle myosin S1 and on M2 and HeLa cells. Due to its drastically improved solubility and photochemical feature, as well as lack of photo- or cytotoxicity, para-aminoblebbistatin may become a feasible replacement for blebbistatin, especially at applications when high concentrations of the inhibitor or blue light irradiation is required. PMID:27241904

  6. A Highly Photostable Hyperbranched Polyglycerol-Based NIR Fluorescence Nanoplatform for Mitochondria-Specific Cell Imaging.

    PubMed

    Dong, Chunhong; Liu, Zhongyun; Liu, Junqing; Wu, Changzhu; Neumann, Falko; Wang, Hanjie; Schäfer-Korting, Monika; Kleuser, Burkhard; Chang, Jin; Li, Wenzhong; Ma, Nan; Haag, Rainer

    2016-09-01

    Considering the critical role of mitochondria in the life and death of cells, non-invasive long-term tracking of mitochondria has attracted considerable interest. However, a high-performance mitochondria-specific labeling probe with high photostability is still lacking. Herein a highly photostable hyperbranched polyglycerol (hPG)-based near-infrared (NIR) quantum dots (QDs) nanoplatform is reported for mitochondria-specific cell imaging. Comprising NIR Zn-Cu-In-S/ZnS QDs as extremely photostable fluorescent labels and alkyl chain (C12 )/triphenylphosphonium (TPP)-functionalized hPG derivatives as protective shell, the tailored QDs@hPG-C12 /TPP nanoprobe with a hydrodynamic diameter of about 65 nm exhibits NIR fluorescence, excellent biocompatibility, good stability, and mitochondria-targeted ability. Cell uptake experiments demonstrate that QDs@hPG-C12 /TPP displays a significantly enhanced uptake in HeLa cells compared to nontargeted QDs@hPG-C12 . Further co-localization study indicates that the probe selectively targets mitochondria. Importantly, compared with commercial deep-red mitochondria dyes, QDs@hPG-C12 /TPP possesses superior photostability under continuous laser irradiation, indicating great potential for long-term mitochondria labeling and tracking. Moreover, drug-loaded QDs@hPG-C12 /TPP display an enhanced tumor cell killing efficacy compared to nontargeted drugs. This work could open the door to the construction of organelle-targeted multifunctional nanoplatforms for precise diagnosis and high-efficient tumor therapy.

  7. High pressure sample cell for total internal reflection fluorescence spectroscopy at pressures up to 2500 bar

    NASA Astrophysics Data System (ADS)

    Koo, Juny; Czeslik, Claus

    2012-08-01

    Total internal reflection fluorescence (TIRF) spectroscopy is a surface sensitive technique that is widely used to characterize the structure and dynamics of molecules at planar liquid-solid interfaces. In particular, biomolecular systems, such as protein adsorbates and lipid membranes can easily be studied by TIRF spectroscopy. Applying pressure to molecular systems offers access to all kinds of volume changes occurring during assembly of molecules, phase transitions, and chemical reactions. So far, most of these volume changes have been characterized in bulk solution, only. Here, we describe the design and performance of a high pressure sample cell that allows for TIRF spectroscopy under high pressures up to 2500 bar (2.5 × 108 Pa), in order to expand the understanding of volume effects from the bulk phase to liquid-solid interfaces. The new sample cell is based on a cylindrical body made of Nimonic 90 alloy and incorporates a pressure transmitting sample cuvette. This cuvette is composed of a fused silica prism and a flexible rubber gasket. It contains the sample solution and ensures a complete separation of the sample from the liquid pressure medium. The sample solution is in contact with the inner wall of the prism forming the interface under study, where fluorescent molecules are immobilized. In this way, the new high pressure TIRF sample cell is very useful for studying any biomolecular layer that can be deposited at a planar water-silica interface. As examples, high pressure TIRF data of adsorbed lysozyme and two phospholipid membranes are presented.

  8. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  9. Trapping a Highly Reactive Nonheme Iron Intermediate That Oxygenates Strong C-H Bonds with Stereoretention.

    PubMed

    Serrano-Plana, Joan; Oloo, Williamson N; Acosta-Rueda, Laura; Meier, Katlyn K; Verdejo, Begoña; García-España, Enrique; Basallote, Manuel G; Münck, Eckard; Que, Lawrence; Company, Anna; Costas, Miquel

    2015-12-23

    An unprecedentedly reactive iron species (2) has been generated by reaction of excess peracetic acid with a mononuclear iron complex [Fe(II)(CF3SO3)2(PyNMe3)] (1) at cryogenic temperatures, and characterized spectroscopically. Compound 2 is kinetically competent for breaking strong C-H bonds of alkanes (BDE ≈ 100 kcal·mol(-1)) through a hydrogen-atom transfer mechanism, and the transformations proceed with stereoretention and regioselectively, responding to bond strength, as well as to steric and polar effects. Bimolecular reaction rates are at least an order of magnitude faster than those of the most reactive synthetic high-valent nonheme oxoiron species described to date. EPR studies in tandem with kinetic analysis show that the 490 nm chromophore of 2 is associated with two S = 1/2 species in rapid equilibrium. The minor component 2a (∼5% iron) has g-values at 2.20, 2.19, and 1.99 characteristic of a low-spin iron(III) center, and it is assigned as [Fe(III)(OOAc)(PyNMe3)](2+), also by comparison with the EPR parameters of the structurally characterized hydroxamate analogue [Fe(III)(tBuCON(H)O)(PyNMe3)](2+) (4). The major component 2b (∼40% iron, g-values = 2.07, 2.01, 1.95) has unusual EPR parameters, and it is proposed to be [Fe(V)(O)(OAc)(PyNMe3)](2+), where the O-O bond in 2a has been broken. Consistent with this assignment, 2b undergoes exchange of its acetate ligand with CD3CO2D and very rapidly reacts with olefins to produce the corresponding cis-1,2-hydroxoacetate product. Therefore, this work constitutes the first example where a synthetic nonheme iron species responsible for stereospecific and site selective C-H hydroxylation is spectroscopically trapped, and its catalytic reactivity against C-H bonds can be directly interrogated by kinetic methods. The accumulated evidence indicates that 2 consists mainly of an extraordinarily reactive [Fe(V)(O)(OAc)(PyNMe3)](2+) (2b) species capable of hydroxylating unactivated alkyl C-H bonds with

  10. Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

    SciTech Connect

    Särhammar, Erik Berg, Sören; Nyberg, Tomas

    2014-07-01

    This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

  11. Highly sensitive SnO2 sensor via reactive laser-induced transfer.

    PubMed

    Palla Papavlu, Alexandra; Mattle, Thomas; Temmel, Sandra; Lehmann, Ulrike; Hintennach, Andreas; Grisel, Alain; Wokaun, Alexander; Lippert, Thomas

    2016-04-27

    Gas sensors based on tin oxide (SnO2) and palladium doped SnO2 (Pd:SnO2) active materials are fabricated by a laser printing method, i.e. reactive laser-induced forward transfer (rLIFT). Thin films from tin based metal-complex precursors are prepared by spin coating and then laser transferred with high resolution onto sensor structures. The devices fabricated by rLIFT exhibit low ppm sensitivity towards ethanol and methane as well as good stability with respect to air, moisture, and time. Promising results are obtained by applying rLIFT to transfer metal-complex precursors onto uncoated commercial gas sensors. We could show that rLIFT onto commercial sensors is possible if the sensor structures are reinforced prior to printing. The rLIFT fabricated sensors show up to 4 times higher sensitivities then the commercial sensors (with inkjet printed SnO2). In addition, the selectivity towards CH4 of the Pd:SnO2 sensors is significantly enhanced compared to the pure SnO2 sensors. Our results indicate that the reactive laser transfer technique applied here represents an important technical step for the realization of improved gas detection systems with wide-ranging applications in environmental and health monitoring control.

  12. Highly sensitive SnO2 sensor via reactive laser-induced transfer

    PubMed Central

    Palla Papavlu, Alexandra; Mattle, Thomas; Temmel, Sandra; Lehmann, Ulrike; Hintennach, Andreas; Grisel, Alain; Wokaun, Alexander; Lippert, Thomas

    2016-01-01

    Gas sensors based on tin oxide (SnO2) and palladium doped SnO2 (Pd:SnO2) active materials are fabricated by a laser printing method, i.e. reactive laser-induced forward transfer (rLIFT). Thin films from tin based metal-complex precursors are prepared by spin coating and then laser transferred with high resolution onto sensor structures. The devices fabricated by rLIFT exhibit low ppm sensitivity towards ethanol and methane as well as good stability with respect to air, moisture, and time. Promising results are obtained by applying rLIFT to transfer metal-complex precursors onto uncoated commercial gas sensors. We could show that rLIFT onto commercial sensors is possible if the sensor structures are reinforced prior to printing. The rLIFT fabricated sensors show up to 4 times higher sensitivities then the commercial sensors (with inkjet printed SnO2). In addition, the selectivity towards CH4 of the Pd:SnO2 sensors is significantly enhanced compared to the pure SnO2 sensors. Our results indicate that the reactive laser transfer technique applied here represents an important technical step for the realization of improved gas detection systems with wide-ranging applications in environmental and health monitoring control. PMID:27118531

  13. Highly sensitive SnO2 sensor via reactive laser-induced transfer

    NASA Astrophysics Data System (ADS)

    Palla Papavlu, Alexandra; Mattle, Thomas; Temmel, Sandra; Lehmann, Ulrike; Hintennach, Andreas; Grisel, Alain; Wokaun, Alexander; Lippert, Thomas

    2016-04-01

    Gas sensors based on tin oxide (SnO2) and palladium doped SnO2 (Pd:SnO2) active materials are fabricated by a laser printing method, i.e. reactive laser-induced forward transfer (rLIFT). Thin films from tin based metal-complex precursors are prepared by spin coating and then laser transferred with high resolution onto sensor structures. The devices fabricated by rLIFT exhibit low ppm sensitivity towards ethanol and methane as well as good stability with respect to air, moisture, and time. Promising results are obtained by applying rLIFT to transfer metal-complex precursors onto uncoated commercial gas sensors. We could show that rLIFT onto commercial sensors is possible if the sensor structures are reinforced prior to printing. The rLIFT fabricated sensors show up to 4 times higher sensitivities then the commercial sensors (with inkjet printed SnO2). In addition, the selectivity towards CH4 of the Pd:SnO2 sensors is significantly enhanced compared to the pure SnO2 sensors. Our results indicate that the reactive laser transfer technique applied here represents an important technical step for the realization of improved gas detection systems with wide-ranging applications in environmental and health monitoring control.

  14. Highly parameterized inversion of groundwater reactive transport for a complex field site

    NASA Astrophysics Data System (ADS)

    Carniato, Luca; Schoups, Gerrit; van de Giesen, Nick; Seuntjens, Piet; Bastiaens, Leen; Sapion, Hans

    2015-02-01

    In this study a numerical groundwater reactive transport model of a shallow groundwater aquifer contaminated with volatile organic compounds is developed. In addition to advective-dispersive transport, the model includes contaminant release from source areas, natural attenuation, abiotic degradation by a permeable reactive barrier at the site, and dilution by infiltrating rain. Aquifer heterogeneity is parameterized using pilot points for hydraulic conductivity, specific yield and groundwater recharge. A methodology is developed and applied to estimate the large number of parameters from the limited data at the field site (groundwater levels, groundwater concentrations of multiple chemical species, point-scale measurements of soil hydraulic conductivity, and lab-scale derived information on chemical and biochemical reactions). The proposed methodology relies on pilot point parameterization of hydraulic parameters and groundwater recharge, a regularization procedure to reconcile the large number of spatially distributed model parameters with the limited field data, a step-wise approach for integrating the different data sets into the model, and high performance computing. The methodology was proven to be effective in reproducing multiple contaminant plumes and in reducing the prior parameter uncertainty of hydraulic conductivity and groundwater recharge. Our results further indicate that contaminant transport predictions are strongly affected by the choice of the groundwater recharge model and flow parameters should be identified using both head and concentration measurements.

  15. Highly parameterized inversion of groundwater reactive transport for a complex field site.

    PubMed

    Carniato, Luca; Schoups, Gerrit; van de Giesen, Nick; Seuntjens, Piet; Bastiaens, Leen; Sapion, Hans

    2015-02-01

    In this study a numerical groundwater reactive transport model of a shallow groundwater aquifer contaminated with volatile organic compounds is developed. In addition to advective-dispersive transport, the model includes contaminant release from source areas, natural attenuation, abiotic degradation by a permeable reactive barrier at the site, and dilution by infiltrating rain. Aquifer heterogeneity is parameterized using pilot points for hydraulic conductivity, specific yield and groundwater recharge. A methodology is developed and applied to estimate the large number of parameters from the limited data at the field site (groundwater levels, groundwater concentrations of multiple chemical species, point-scale measurements of soil hydraulic conductivity, and lab-scale derived information on chemical and biochemical reactions). The proposed methodology relies on pilot point parameterization of hydraulic parameters and groundwater recharge, a regularization procedure to reconcile the large number of spatially distributed model parameters with the limited field data, a step-wise approach for integrating the different data sets into the model, and high performance computing. The methodology was proven to be effective in reproducing multiple contaminant plumes and in reducing the prior parameter uncertainty of hydraulic conductivity and groundwater recharge. Our results further indicate that contaminant transport predictions are strongly affected by the choice of the groundwater recharge model and flow parameters should be identified using both head and concentration measurements.

  16. Synthesis, solubilization, and surface functionalization of highly fluorescent quantum dots for cellular targeting through a small molecule

    NASA Astrophysics Data System (ADS)

    Galloway, Justin F.

    To achieve long-term fluorescence imaging with quantum dots (QDs), a CdSe core/shell must first be synthesized. The synthesis of bright CdSe QDs is not trivial and as a consequence, the role of surfactant in nucleation and growth was investigated. It was found that the type of surfactant used, either phosphonic or fatty acid, played a pivotal role in the size of the CdSe core. The study of surfactant on CdSe synthesis, ultimately led to an electrical passivation method that utilized a short-chained phosphonic acid and highly reactive organometallic precursors to achieve high quantum yield (QY) as has been previously described. The synthesis of QDs using organometallic precursors and a phosphonic acid for passivation resulted in 4 out of 9 batches of QDs achieving QYs greater than 50% and 8 out of 9 batches with QYs greater than 35%. The synthesis of CdSe QDs was done in organic solutions rendering the surface of the particle hydrophobic. To perform cell-targeting experiments, QDs must be transferred to water. The transfer of QDs to water was successfully accomplished by using single acyl chain lipids. A systematic study of different lipid combinations and coatings demonstrated that 20-40 mol% single acyl chained lipids were able to transfer QDs to water resulting in monodispersed, stable QDs without adversely affecting the QY. The advantage to water solubilization using single acyl chain lipids is that the QD have a hydrodynamic radius less than 15 nm, QYs that can exceed 50% and additional surface functionalization can be down using the reactive sites incorporated into the lipid bilayer. QDs that are bright and stable in water were studied for the purpose of targeting G protein-coupled Receptors (GPCR). GPCRs are transmembrane receptors that internalize extracellular cues, and thus mediate signal transduction. The cyclic Adenosine Monophosphate Receptor 1 of the model organism Dictyostelium disodium was the receptor of interest. The Halo protein, a genetically

  17. Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Oh, Gyungseok; Chung, Euiheon; Yun, Seok H.

    2013-12-01

    Optical fiber-based high-resolution fluorescence imaging techniques have promising applications in clinical practice and preclinical research using animals. Here we review the instrumentation and applications of microendoscopy based on various types of optical fibers. Single-mode fibers and double-clad fibers have been widely used for delivering light from light sources to tissues and collecting light from tissues to photodetectors. Coherent fiber bundles, cylindrical graded-index lenses, and multi-mode fibers have been employed in both beam-scanning and non-scanning microscopy. With continuing advances of optical fiber technologies, further innovations in optical microendoscopy are expected.

  18. Rapid determination of succinylcholine in human plasma by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Lagerwerf, A J; Vanlinthout, L E; Vree, T B

    1991-10-04

    A high-performance liquid chromatographic method with fluorometric detection has been developed for the determination of succinylcholine in human plasma. Succinylcholine shows fluorescence at 282 nm with an excitation at 257 nm. The assay is sensitive, reproducible and linear for concentrations ranging from 100 ng/ml to 100 micrograms/ml of succinylcholine. In a pilot study the plasma concentration-time curve showed a triphasic elimination, with half-lives of 0.4, 1.2 and 8 min, respectively. In a clinical setting, drugs commonly administered during anaesthesia did not interfere with the assay. This method provides a simple and time-saving alternative to existing methods.

  19. High efficiency fluorescent excimer lamps: An alternative to mercury based UVC lamps

    SciTech Connect

    Masoud, N. M.; Murnick, D. E.

    2013-12-15

    A high efficiency xenon excimer lamp radiating at 172 nm, with an internal phosphor coating shifting to UVC has been demonstrated, showing the feasibility of a cost effective alternative to UVC mercury lamps. Fluorescent lamps so designed can be fabricated in various geometries with high efficiency. Unlike other xenon excimer lamps based on dielectric barrier discharges this new system is highly compatible with existing and proposed phosphors as it operates in an inert gas environment at modest temperature and is subject only to 172 nm primary radiation. Using a lamp coated with a UVC phosphor we have demonstrated the feasibility of germicidal and curing lamps with 40% energy conversion efficiency and high power density. These lamps are rapidly switchable, have long projected lifetimes and are compatible with dimmers.

  20. Synthesis of highly fluorescent metal (Ag, Au, Pt, and Cu) nanoclusters by electrostatically induced reversible phase transfer.

    PubMed

    Yuan, Xun; Luo, Zhentao; Zhang, Qingbo; Zhang, Xinhai; Zheng, Yuangang; Lee, Jim Yang; Xie, Jianping

    2011-11-22

    This paper reports a simple and scalable method for the synthesis of highly fluorescent Ag, Au, Pt, and Cu nanoclusters (NCs) based on a mild etching environment made possible by phase transfer via electrostatic interactions. Using Ag as a model metal, a simple and fast (total synthesis time < 3 h) phase transfer cycle (aqueous → organic (2 h incubation) → aqueous) has been developed to process originally polydisperse, nonfluorescent, and unstable Ag NCs into monodisperse, highly fluorescent, and extremely stable Ag NCs in the same phase (aqueous) and protected by the same thiol ligand. The synthetic protocol was successfully extended to fabricate highly fluorescent Ag NCs protected by custom-designed peptides with desired functionalities (e.g., carboxyl, hydroxyl, and amine). The facile synthetic method developed in this study should largely contribute to the practical applications of this new class of fluorescence probes.

  1. Modulation of reactive oxygen species by salicylic acid in Arabidopsis seed germination under high salinity.

    PubMed

    Lee, Sangmin; Park, Chung-Mo

    2010-12-01

    Potential roles of salicylic acid (SA) on seed germination have been explored in many plant species. However, it is still controversial how SA regulates seed germination, mainly because the results have been somewhat variable, depending on plant genotypes used and experimental conditions employed. We found that SA promotes seed germination under high salinity in Arabidopsis. Seed germination of the sid2 mutant, which has a defect in SA biosynthesis, is hypersensitive to high salinity, but the inhibitory effects are reduced in the presence of physiological concentrations of SA. Abiotic stresses, including high salinity, impose oxidative stress on plants. Endogenous contents of H(2)O(2) are higher in the sid2 mutant seeds. However, exogenous application of SA reduces endogenous level of reactive oxygen species (ROS), indicating that SA is involved in plant responses to ROS-mediated damage under abiotic stress conditions. Gibberellic acid (GA), a plant hormone closely associated with seed germination, also reverses the inhibitory effects of high salinity on seed germination and seedling establishment. Under high salinity, GA stimulates SA biosynthesis by inducing the SID2 gene. Notably, SA also induces genes encoding GA biosynthetic enzymes. These observations indicate that SA promotes seed germination under high salinity by modulating antioxidant activity through signaling crosstalks with GA.

  2. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  3. High Platelet Reactivity in Patients with Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention: Randomised Controlled Trial Comparing Prasugrel and Clopidogrel

    PubMed Central

    Geisler, Tobias; Booth, Jean; Tavlaki, Elli; Karathanos, Athanasios; Müller, Karin; Droppa, Michal; Gawaz, Meinrad; Yanez-Lopez, Monica; Davidson, Simon J.; Stables, Rod H.; Banya, Winston; Zaman, Azfar; Flather, Marcus; Dalby, Miles

    2015-01-01

    Background Prasugrel is more effective than clopidogrel in reducing platelet aggregation in acute coronary syndromes. Data available on prasugrel reloading in clopidogrel treated patients with high residual platelet reactivity (HRPR) i.e. poor responders, is limited. Objectives To determine the effects of prasugrel loading on platelet function in patients on clopidogrel and high platelet reactivity undergoing percutaneous coronary intervention for acute coronary syndrome (ACS). Patients Patients with ACS on clopidogrel who were scheduled for PCI found to have a platelet reactivity ≥40 AUC with the Multiplate Analyzer, i.e. “poor responders” were randomised to prasugrel (60 mg loading and 10 mg maintenance dose) or clopidogrel (600 mg reloading and 150 mg maintenance dose). The primary outcome measure was proportion of patients with platelet reactivity <40 AUC 4 hours after loading with study medication, and also at one hour (secondary outcome). 44 patients were enrolled and the study was terminated early as clopidogrel use decreased sharply due to introduction of newer P2Y12 inhibitors. Results At 4 hours after study medication 100% of patients treated with prasugrel compared to 91% of those treated with clopidogrel had platelet reactivity <40 AUC (p = 0.49), while at 1 hour the proportions were 95% and 64% respectively (p = 0.02). Mean platelet reactivity at 4 and 1 hours after study medication in prasugrel and clopidogrel groups respectively were 12 versus 22 (p = 0.005) and 19 versus 34 (p = 0.01) respectively. Conclusions Routine platelet function testing identifies patients with high residual platelet reactivity (“poor responders”) on clopidogrel. A strategy of prasugrel rather than clopidogrel reloading results in earlier and more sustained suppression of platelet reactivity. Future trials need to identify if this translates into clinical benefit. Trial Registration ClinicalTrials.gov NCT01339026 PMID:26317618

  4. Fluorescence Quenching Nanoprobes Dedicated to In Vivo Photoacoustic Imaging and High-Efficient Tumor Therapy in Deep-Seated Tissue.

    PubMed

    Qin, Huan; Zhou, Ting; Yang, Sihua; Xing, Da

    2015-06-10

    Photoacoustic imaging (PAI) and photoacoustic (PA) therapy have promising applications for treating tumors. It is known that the utilization of high-absorption-coefficient probes can selectively enhance the PAI target contrast and PA tumor therapy efficiency in deep-seated tissue. Here, the design of a probe with the highest availability of optical-thermo conversion by using graphene oxide (GO) and dyes via π-π stacking interactions is reported. The GO serves as a base material for loading dyes and quenching dye fluorescence via fluorescence resonance energy transfer (FRET), with the one purpose of maximum of PA efficiency. Experiments verify that the designed fluorescence quenching nanoprobes can produce stronger PA signals than the sum of the separate signals generated in the dye and the GO. Potential applications of the fluorescence quenching nanoprobes are demonstrated, dedicating to enhance PA contrast of targets in deep-seated tissues and tumors in living mice. PA therapy efficiency both in vitro and in vivo by using the fluorescence quenching nanoprobes is found to be higher than with the commonly used PA therapy agents. Taken together, quenching dye fluorescence via FRET will provide a valid means for developing high-efficiency PA probes. Fluorescence quenching nanoprobes are likely to become a promising candidate for deep-seated tumor imaging and therapy.

  5. A High-Performance Fluorescence Immunoassay Based on the Relaxation of Quenching, Exemplified by Detection of Cardiac Troponin I.

    PubMed

    Kim, Seung-Wan; Cho, Il-Hoon; Park, Ji-Na; Seo, Sung-Min; Paek, Se-Hwan

    2016-05-10

    The intramolecular fluorescence self-quenching phenomenon is a major drawback in developing high-performance fluorometric biosensors which use common fluorophores as signal generators. We propose two strategies involving liberation of the fluorescent molecules by means of enzymatic fragmentation of protein or dehybridization of double-stranded DNA. In the former, bovine serum albumin (BSA) was coupled with the fluorescent BODIPY dye (Red BSA), and then immobilized on a solid surface. When the insolubilized Red BSA was treated with proteinase K (10 units/mL) for 30 min, the fluorescent signal was significantly increased (3.5-fold) compared to the untreated control. In the second case, fluorophore-tagged DNA probes were linked to gold nanoparticles by hybridization with capture DNA strands densely immobilized on the surface. The quenched fluorescence signal was recovered (3.7-fold) by thermal dehybridization, which was induced with light of a specific wavelength (e.g., 530 nm) for less than 1 min. We next applied the Red BSA self-quenching relaxation technique employing enzymatic fragmentation to a high-performance immunoassay of cardiac troponin I (cTnI) in a microtiter plate format. The detection limit was 0.19 ng/mL cTnI, and the fluorescent signal was enhanced approximately 4.1-fold compared with the conventional method of direct measurement of the fluorescent signal from a non-fragmented fluorophore-labeled antibody.

  6. Application of a high-resolution x-ray fluorescence analyzer.

    SciTech Connect

    Adams, B. W.; Attenkofer, K.; Experimental Facilities Division

    2006-01-01

    We have developed a high resolution x-ray fluorescence analyzer based on the principle of active optics. It combines a resolution of ca. 5 eV with a tunability over several keV and a wide solid-angle coverage (ca. 2 by 5 degrees). To date, this analyzer has been used in near-edge spectroscopy of gallium in GaAs, and for the detection and chemical speciation of trace amounts platinum in soot from an diesel engine. The latter application illustrates the use of the analyzer to enhance the signal-to-background ratio in trace-element x-ray fluorescence analysis. The analyzer is shown schematically in Fig. 1. In it, a strip of silicon is bent by an axial force from two pushers at its ends, and eight correctors act from above to bring the shape of the bent crystal to approximate a logarithmic spiral. A more detailed description of the device, its underlying theory, and adjustment procedures may be found elsewhere. The sample consisted of soot collected from the exhaust of a diesel engine burning a fuel with a platinum-based additive that was tested for the purpose of facilitating clean combustion. The concentration of platinum in the soot was about 100 ppm, and the chemical speciation (oxidation state, dispersed or in the form of nanoparticles, etc.) was unknown. A small speck of this soot containing 10{sup 12} to 10{sup 13} atoms was placed into the x-ray beam of the 11-ID-D station of the APS. The incident photon energy was scanned over the Pt L{sub 3} edge, and the Pt L{sub {alpha}1} fluorescence was detected using two silicon drift detectors (Vortex), one directly and one with the analyzer. The purpose of the analyzer in this application was to enhance the energy resolution by a factor of about 50 (250 eV for the drift detector, 5 eV for the analyzer), and thus reduce the background of elastically or Compton-scattered photons, while keeping the fluorescent line. Whereas the detector with the analyzer recorded a clear signature of platinum in the form of an absorption

  7. Oxygen Pathway Modeling Estimates High Reactive Oxygen Species Production above the Highest Permanent Human Habitation

    PubMed Central

    Cano, Isaac; Selivanov, Vitaly; Gomez-Cabrero, David; Tegnér, Jesper; Roca, Josep; Wagner, Peter D.; Cascante, Marta

    2014-01-01

    The production of reactive oxygen species (ROS) from the inner mitochondrial membrane is one of many fundamental processes governing the balance between health and disease. It is well known that ROS are necessary signaling molecules in gene expression, yet when expressed at high levels, ROS may cause oxidative stress and cell damage. Both hypoxia and hyperoxia may alter ROS production by changing mitochondrial Po2 (). Because depends on the balance between O2 transport and utilization, we formulated an integrative mathematical model of O2 transport and utilization in skeletal muscle to predict conditions to cause abnormally high ROS generation. Simulations using data from healthy subjects during maximal exercise at sea level reveal little mitochondrial ROS production. However, altitude triggers high mitochondrial ROS production in muscle regions with high metabolic capacity but limited O2 delivery. This altitude roughly coincides with the highest location of permanent human habitation. Above 25,000 ft., more than 90% of exercising muscle is predicted to produce abnormally high levels of ROS, corresponding to the “death zone” in mountaineering. PMID:25375931

  8. Micro vapor bubble jet flow for safe and high-rate fluorescence-activated cell sorting.

    PubMed

    de Wijs, Koen; Liu, Chengxun; Dusa, Alexandra; Vercruysse, Dries; Majeed, Bivragh; Tezcan, Deniz Sabuncuoglu; Blaszkiewicz, Kamil; Loo, Josine; Lagae, Liesbet

    2017-03-29

    Safe, high-rate and cost-effective cell sorting is important for clinical cell isolation. However, commercial fluorescence-activated cell sorters (FACS) are expensive and prone to aerosol-induced sample contamination. Here we report a microfluidic cell sorter allowing high rate and fully enclosed cell sorting. The sorter chip consists of an array of micro heating hotspots. Pulsed resistive heating in the hotspots produces numerous micro vapor bubbles with short duration, which gives rise to a rapid jet flow for cell sorting. With this method, we demonstrated high sorting rate comparable to commercial FACS and the significant enrichment of rare cancer cells. This vapor bubble based cell sorting method can be a powerful tool for contamination-free and affordable clinical cell sorting such as circulating tumor cell isolation and cancer cell therapy.

  9. High performance low-cost polarizer using depolarization of a polarized light by reactive mesogen.

    PubMed

    Kim, Bong Choon; Lim, Young Jin; Ha, Kyung Su; Lee, Seung Hee; Kang, Wan-Seok; Lee, Gi-Dong

    2011-08-15

    Currently, the polyethlene terephthalate (PET) film challenges to substitute Tri-acetyl cellulouse (TAC) film which is a protection film in a polarizer layer, because of low cost of PET film. On the contrary, the PET film shows an optical problem such that color shift or interference optical pattern in oblique direction can occur because the film is made with the lamination process, which induces high phase retardation. In this paper, we propose a color shift free low cost polarizer by polymerization of random oriented reactive mesogen (RM) on the PET film. We calculate the viewing angle performance of the polarizer with the conventional PET film, with the TAC film and with the proposed PET film. As a result, we confirm that the proposed optical configuration can satisfy the optical performance equivalent to that of conventional TAC film uses in addition to the cost-down.

  10. High osmotic pressure increases reactive oxygen species generation in rabbit corneal epithelial cells by endoplasmic reticulum

    PubMed Central

    Wang, Peng; Sheng, Minjie; Li, Bing; Jiang, Yaping; Chen, Yihui

    2016-01-01

    Tear high osmotic pressure (HOP) has been recognized as the core mechanism underlying ocular surface inflammation, injury and symptoms and is closely associated with many ocular surface diseases, especially dry eye. The endoplasmic reticulum (ER) is a multi-functional organelle responsible for protein synthesis, folding and transport, biological synthesis of lipids, vesicle transport and intracellular calcium storage. Accumulation of unfolded proteins and imbalance of calcium ion in the ER would induce ER stress and protective unfolded protein response (UPR). Many studies have demonstrated that ER stress can induce cell apoptosis. However, the association between tear HOP and ER stress has not been studied systematically. In the present study, rabbit corneal epithelial cells were treated with HOP and results showed that the production of reactive oxygen species increased markedly, which further activated the ER signaling pathway and ultimately induced cell apoptosis. These findings shed new lights on the pathogenesis and clinical treatment of dry eye and other ocular surface diseases. PMID:27158374

  11. High-temperature thermal degradation of polyethylene from reactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Moore, Nathan W.

    Thermal degradation of polyethylene is studied under extremely high-rate temperature ramp rates from 1014 to 1010 K/s in isochoric, condensed phases. The molecular evolution and macroscopic state variables are extracted as a function of density from reactive molecular dynamics simulations using the ReaxFF potential. These results are used to parameterize a kinetic rate model for the dissociation and coalescence of hydrocarbons as a function of temperature, temperature ramp rate, and density. The results are contrasted to first-order random-scission macrokinetic models often assumed for pyrolysis of linear polyethylene under ambient conditions. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04- 94AL85000.

  12. A flavone-based turn-on fluorescent probe for intracellular cysteine/homocysteine sensing with high selectivity.

    PubMed

    Zhang, Jian; Lv, Yanlin; Zhang, Wei; Ding, Hui; Liu, Rongji; Zhao, Yongsheng; Zhang, Guangjin; Tian, Zhiyuan

    2016-01-01

    A new type of flavone-based fluorescent probe (DMAF) capable of cysteine (Cys)/homocysteine (Hcy) sensing with high selectivity over other amino acids was developed. Such type of probe undergoes Cys/Hcy-mediated cyclization reaction with the involvement of its aldehyde group, which suppresses of the photoinduced electron transfer (PET) process of the probe molecule and consequently leads to the enhancement of fluorescence emission upon excitation using visible light. The formation of product of the Cys/Hcy-mediated cyclization reaction was confirmed and the preliminary fluorescence imaging experiments revealed the biocompatibility of the as-prepared probe and validated its practicability for intracellular Cys/Hcy sensing.

  13. High-rate reactive magnetron sputtering of zirconia films for laser optics applications

    NASA Astrophysics Data System (ADS)

    Juškevičius, K.; Audronis, M.; Subačius, A.; Drazdys, R.; Juškėnas, R.; Matthews, A.; Leyland, A.

    2014-09-01

    ZrO2 exhibits low optical absorption in the near-UV range and is one of the highest laser-induced damage threshold (LIDT) materials; it is, therefore, very attractive for laser optics applications. This paper reports explorations of reactive sputtering technology for deposition of ZrO2 films with low extinction coefficient k values in the UV spectrum region at low substrate temperature. A high deposition rate (64 % of the pure metal rate) process is obtained by employing active feedback reactive gas control which creates a stable and repeatable deposition processes in the transition region. Substrate heating at 200 °C was found to have no significant effect on the optical ZrO2 film properties. The addition of nitrogen to a closed-loop controlled process was found to have mostly negative effects in terms of deposition rate and optical properties. Open-loop O2 gas-regulated ZrO2 film deposition is slow and requires elevated (200 °C) substrate temperature or post-deposition annealing to reduce absorption losses. Refractive indices of the films were distributed in the range n = 2.05-2.20 at 1,000 nm and extinction coefficients were in the range k = 0.6 × 10-4 and 4.8 × 10-3 at 350 nm. X-ray diffraction analysis showed crystalline ZrO2 films consisted of monoclinic + tetragonal phases when produced in Ar/O2 atmosphere and monoclinic + rhombohedral or a single rhombohedral phase when produced in Ar/O2 + N2. Optical and physical properties of the ZrO2 layers produced in this study are suitable for high-power laser applications in the near-UV range.

  14. A CT-analogous method for high-resolution fluorescence molecular tomography

    NASA Astrophysics Data System (ADS)

    Li, Jiao; Gao, Feng; Zhu, Qingzhen; Li, Fenghui; Wang, Xin; Zhang, Limin; Zhao, Huijuan

    2012-03-01

    In vivo biomedical imaging using near-infrared light must overcome the effects of highly light scattering, which limit the spatial resolution and affect image quality. The high-resolution, sensitive and quantitative fluorescence imaging tool is an urgent need for the applications in small-animal imaging and clinical cancer research. A CT-analogous method for fluorescence molecular tomography (FMT) on small-animal-sized models is presented to improve the spatial resolution of FMT to a limit of several millimeters, depending on the size of the tissue region to be imaged. The method combines FMT physics with the filtered back-projection scheme for image reconstruction of the fan-beam computed tomography, based on the early-photon detection of time-resolved optical signals, and is suitable for two-dimensional (2D) imaging of small size biological models. By use of a normalized Born formulation for the inversion, the algorithm is validated using full time-resolved simulated data for 2D phantom that are generated from a hybrid finite-element and finite-time-difference photon diffusion modeling, and its superiority in the improvement of the spatial resolution is demonstrated by imaging different target-to-background contrast ratios.

  15. Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging.

    PubMed

    Fan, Hai-Ming; Olivo, Malini; Shuter, Borys; Yi, Jia-Bao; Bhuvaneswari, Ramaswamy; Tan, Hui-Ru; Xing, Gui-Chuan; Ng, Cheng-Teng; Liu, Lei; Lucky, Sasidharan S; Bay, Boon-Huat; Ding, Jun

    2010-10-27

    In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.

  16. High speed velocimetry and concentration measurements in a microfluidic mixer using fluorescence confocal microscopy

    NASA Astrophysics Data System (ADS)

    Inguva, Venkatesh; Perot, Blair; Kathuria, Sagar; Rothstein, Jonathan; Bilsel, Osman

    2016-11-01

    This work experimentally examines the performance of a quasi-turbulent micro-mixer that was designed to produce rapid mixing for protein-folding experiments. The original design of the mixer was performed using Direct Numerical Simulation (DNS) of the flow field and LES of the high Sc number scalar field representing the protein. The experimental work is designed to validate the DNS results. Both the velocity field and the protein concentration require validation. Different experiments were carried out to measure these two quantities. Concentration measurements are performed using a 488nm continuous wave laser coupled with a confocal microscope to measure fluorescence intensity during mixing. This is calibrated using the case where no mixing occurs. The velocity measurements use a novel high speed velocimetry technique capable of measuring speeds on the order of 10 m/s in a micro channel. The technique involves creating a pulsed confocal volume from a Ti-Sapphire laser with a pulse width of 260ns and observing the decay of fluorescence due to the fluid motion. Results from both experiments will be presented along with a comparison to the DNS results. The work is supported by NSF IDBR Award No. 1353942.

  17. Novel fluorescently labeled peptide compounds for detection of oxidized low-density lipoprotein at high specificity.

    PubMed

    Sato, Akira; Yamanaka, Hikaru; Oe, Keitaro; Yamazaki, Yoji; Ebina, Keiichi

    2014-10-01

    The probes for specific detection of oxidized low-density lipoprotein (ox-LDL) in plasma and in atherosclerotic plaques are expected to be useful for the identification, diagnosis, prevention, and treatment for atherosclerosis. In this study, to develop a fluorescent peptide probe for specific detection of ox-LDL, we investigated the interaction of fluorescein isothiocyanate (FITC)-labeled peptides with ox-LDL using polyacrylamide gel electrophoresis. Two heptapeptides (KWYKDGD and KP6) coupled through the ε-amino group of K at the N-terminus to FITC in the presence/absence of 6-amino-n-caproic acid (AC) linker to FITC--(FITC-AC)KP6 and (FITC)KP6--both bound with high specificity to ox-LDL in a dose-dependent manner. In contrast, a tetrapeptide (YKDG) labeled with FITC at the N-terminus and a pentapeptide (YKDGK) coupled through the ε-amino group of K at the C-terminus to FITC did not bind selectively to ox-LDL. Furthermore, (FITC)KP6 and (FITC-AC)KP6 bound with high specificity to the protein in mouse plasma (probably ox-LDL fraction). These findings strongly suggest that (FITC)KP6 and (FITC-AC)KP6 may be effective novel fluorescent probes for specific detection of ox-LDL.

  18. High-throughput fluorescence-activated cell sorting for lipid hyperaccumulating Chlamydomonas reinhardtii mutants.

    PubMed

    Xie, Bo; Stessman, Dan; Hart, Jason H; Dong, Haili; Wang, Yingjun; Wright, David A; Nikolau, Basil J; Spalding, Martin H; Halverson, Larry J

    2014-09-01

    The genetically tractable microalga Chlamydomonas reinhardtii has many advantages as a model for renewable bioproducts and/or biofuels production. However, one limitation of C. reinhardtii is its relatively low-lipid content compared with some other algal species. To overcome this limitation, we combined ethane methyl sulfonate mutagenesis with fluorescence-activated cell sorting (FACS) of cells stained with the lipophilic stain Nile Red to isolate lipid hyperaccumulating mutants of C. reinhardtii. By manipulating the FACS gates, we sorted mutagenized cells with extremely high Nile Red fluorescence signals that were rarely detected in nonmutagenized populations. This strategy successfully isolated several putative lipid hyperaccumulating mutants exhibiting 23% to 58% (dry weight basis) higher fatty acid contents than their progenitor strains. Significantly, for most mutants, nitrogen starvation was not required to attain high-lipid content nor was there a requirement for a deficiency in starch accumulation. Microscopy of Nile Red stained cells revealed that some mutants exhibit an increase in the number of lipid bodies, which correlated with TLC analysis of triacyglycerol content. Increased lipid content could also arise through increased biomass production. Collectively, our findings highlight the ability to enhance intracellular lipid accumulation in algae using random mutagenesis in conjunction with a robust FACS and lipid yield verification regime. Our lipid hyperaccumulating mutants could serve as a genetic resource for stacking additional desirable traits to further increase lipid production and for identifying genes contributing to lipid hyperaccumulation, without lengthy lipid-induction periods.

  19. Highly selective and sensitive fluorescent sensor: Thiacalix[4]arene-1-naphthalene carboxylate for Zn2+ ions

    NASA Astrophysics Data System (ADS)

    Darjee, Savan M.; Modi, Krunal M.; Panchal, Urvi; Patel, Chirag; Jain, Vinod K.

    2017-04-01

    Thiacalix[4]arene based fluorescent sensor bearing two naphthoyl groups, thiacalix-1-naphthalene carboxylate (TCNC) has been synthesized and characterized by 1H NMR, 13C NMR, FTIR, ESI-MS spectroscopic techniques. The interaction behavior of TCNC with various metal ions like Fe3+, Hg2+, Co2+, Ni2+, Cu2+, Cd2+, Pb2+, Mg2+, K+, Na+, and Zn2+ was studied by UV-visible and emission spectrophotometry. It was observed that TCNC recognizes Zn2+ ions with high selectivity and sensitivity. The enhancement of fluorescence intensity due to presence of Zn2+ ions was not perturbed in the presence of high concentration of other associated metal ions. The 1:1 stoichiometry of TCNC:Zn2+ complex was confirmed by job's plot, ESI-MS study and 1H NMR titration. The binding constant and quantum yield were also calculated by using spectrofluorimetric titration data. Linear detection range of zinc ions was found to be 1 nM-740 nM. Furthermore, molecular docking study was performed to evaluate the binding affinity and possible interactions between TCNC and Zn2+ depicting that TCNC interact with Zn2+ via weak intramolecular forces. In addition to that molecular dynamics has also been performed to evaluate the conformational changes and it's structural stability in the particular environment.

  20. A highly sensitive ratiometric fluorescent probe for the detection of cytoplasmic and nuclear hydrogen peroxide.

    PubMed

    Wen, Ying; Liu, Keyin; Yang, Huiran; Li, Yi; Lan, Haichuang; Liu, Yi; Zhang, Xinyu; Yi, Tao

    2014-10-07

    As a marker for oxidative stress and a second messenger in signal transduction, hydrogen peroxide (H2O2) plays an important role in living systems. It is thus critical to monitor the changes in H2O2 in cells and tissues. Here, we developed a highly sensitive and versatile ratiometric H2O2 fluorescent probe (NP1) based on 1,8-naphthalimide and boric acid ester. In response to H2O2, the ratio of its fluorescent intensities at 555 and 403 nm changed 1020-fold within 200 min. The detecting limit of NP1 toward H2O2 is estimated as 0.17 μM. It was capable of imaging endogenous H2O2 generated in live RAW 264.7 macrophages as a cellular inflammation response, and especially, it was able to detect H2O2 produced as a signaling molecule in A431 human epidermoid carcinoma cells through stimulation by epidermal growth factor. This probe contains an azide group and thus has the potential to be linked to various molecules via the click reaction. After binding to a Nuclear Localization Signal peptide, the peptide-based combination probe (pep-NP1) was successfully targeted to nuclei and was capable of ratiometrically detecting nuclear H2O2 in living cells. These results indicated that NP1 was a highly sensitive ratiometric H2O2 dye with promising biological applications.

  1. Monochromatic multicomponent fluorescence sedimentation velocity for the study of high-affinity protein interactions

    PubMed Central

    Zhao, Huaying; Fu, Yan; Glasser, Carla; Andrade Alba, Eric J; Mayer, Mark L; Patterson, George; Schuck, Peter

    2016-01-01

    The dynamic assembly of multi-protein complexes underlies fundamental processes in cell biology. A mechanistic understanding of assemblies requires accurate measurement of their stoichiometry, affinity and cooperativity, and frequently consideration of multiple co-existing complexes. Sedimentation velocity analytical ultracentrifugation equipped with fluorescence detection (FDS-SV) allows the characterization of protein complexes free in solution with high size resolution, at concentrations in the nanomolar and picomolar range. Here, we extend the capabilities of FDS-SV with a single excitation wavelength from single-component to multi-component detection using photoswitchable fluorescent proteins (psFPs). We exploit their characteristic quantum yield of photo-switching to imprint spatio-temporal modulations onto the sedimentation signal that reveal different psFP-tagged protein components in the mixture. This novel approach facilitates studies of heterogeneous multi-protein complexes at orders of magnitude lower concentrations and for higher-affinity systems than previously possible. Using this technique we studied high-affinity interactions between the amino-terminal domains of GluA2 and GluA3 AMPA receptors. DOI: http://dx.doi.org/10.7554/eLife.17812.001 PMID:27436096

  2. The Gray Institute ‘open’ high-content, fluorescence lifetime microscopes

    PubMed Central

    BARBER, PR; TULLIS, IDC; PIERCE, GP; NEWMAN, RG; PRENTICE, J; ROWLEY, MI; MATTHEWS, DR; AMEER-BEG, SM; VOJNOVIC, B

    2013-01-01

    Summary We describe a microscopy design methodology and details of microscopes built to this ‘open’ design approach. These demonstrate the first implementation of time-domain fluorescence microscopy in a flexible automated platform with the ability to ease the transition of this and other advanced microscopy techniques from development to use in routine biology applications. This approach allows easy expansion and modification of the platform capabilities, as it moves away from the use of a commercial, monolithic, microscope body to small, commercial off-the-shelf and custom made modular components. Drawings and diagrams of our microscopes have been made available under an open license for noncommercial use at http://users.ox.ac.uk/~atdgroup. Several automated high-content fluorescence microscope implementations have been constructed with this design framework and optimized for specific applications with multiwell plates and tissue microarrays. In particular, three platforms incorporate time-domain FLIM via time-correlated single photon counting in an automated fashion. We also present data from experiments performed on these platforms highlighting their automated wide-field and laser scanning capabilities designed for high-content microscopy. Devices using these designs also form radiation-beam ‘end-stations’ at Oxford and Surrey Universities, showing the versatility and extendibility of this approach. PMID:23772985

  3. A new isoindoline-based highly selective "turn-on" fluorescent chemodosimeter for detection of mercury ion.

    PubMed

    Zali-Boeini, Hassan; Zareh Jonaghani, Mohammad; Fadaei, Negar; Rudbari, Hadi Amiri

    2017-05-05

    A new isoindoline-based highly efficient turn-on fluorescent chemodosimeter S with a thioamide functionality as a binding site for selective detection of Hg(2+) ion has been developed. The chemodosimeter S showed an extreme selectivity for detection of Hg(2+) ion among various two and three-valent metal ions in acetonitrile/water (70/30, v/v). It was found that, in the presence of Hg(2+) ion the non-fluorescent chemodosimeter S was efficiently and rapidly desulfurized to the corresponding highly fluorescent amide 1. A good linear relationship was shown between the fluorescence intensity and the concentration of Hg(2+) within the range of 0-1μM, with a detection limit of 2.03×10(-8)M.

  4. A rapid approach to high-resolution fluorescence imaging in semi-thick brain slices.

    PubMed

    Selever, Jennifer; Kong, Jian-Qiang; Arenkiel, Benjamin R

    2011-07-26

    A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are characteristic to neurons in both normal and diseased brain. Towards this, a great deal of effort has been placed on building high-resolution neuroanatomical maps(1-3). With the expansion of molecular genetics and advances in light microscopy has come the ability to query not only neuronal morphologies, but also the molecular and cellular makeup of individual neurons and their associated networks(4). Major advances in the ability to mark and manipulate neurons through transgenic and gene targeting technologies in the rodent now allow investigators to 'program' neuronal subsets at will(5-6). Arguably, one of the most influential contributions to contemporary neuroscience has been the discovery and cloning of genes encoding fluorescent proteins (FPs) in marine invertebrates(7-8), alongside their subsequent engineering to yield an ever-expanding toolbox of vital reporters(9). Exploiting cell type-specific promoter activity to drive targeted FP expression in discrete neuronal populations now affords neuroanatomical investigation with genetic precision. Engineering FP expression in neurons has vastly improved our understanding of brain structure and function. However, imaging individual neurons and their associated networks in deep brain tissues, or in three dimensions, has remained a challenge. Due to high lipid content, nervous tissue is rather opaque and exhibits auto fluorescence. These inherent biophysical properties make it difficult to visualize and image fluorescently labelled neurons at high resolution using standard epifluorescent or confocal microscopy beyond depths of tens of microns. To circumvent this challenge investigators often employ serial thin-section imaging and reconstruction methods(10), or 2-photon laser scanning microscopy(11). Current drawbacks to these approaches are the associated labor

  5. Highly sensitive fluorescence quantitative detection of specific DNA sequences with molecular beacons and nucleic acid dye SYBR Green I.

    PubMed

    Xiang, Dongshan; Zhai, Kun; Xiang, Wenjun; Wang, Lianzhi

    2014-11-01

    A highly sensitive fluorescence method of quantitative detection for specific DNA sequence is developed based on molecular beacon (MB) and nucleic acid dye SYBR Green I by synchronous fluorescence analysis. It is demonstrated by an oligonucleotide sequence of wild-type HBV (target DNA) as a model system. In this strategy, the fluorophore of MB is designed to be 6-carboxyfluorescein group (FAM), and the maximum excitation wavelength and maximum emission wavelength are both very close to that of SYBR Green I. In the presence of targets DNA, the MBs hybridize with the targets DNA and form double-strand DNA (dsDNA), the fluorophore FAM is separated from the quencher BHQ-1, thus the fluorophore emit fluorescence. At the same time, SYBR Green I binds to dsDNA, the fluorescence intensity of SYBR Green I is significantly enhanced. When targets DNA are detected by synchronous fluorescence analysis, the fluorescence peaks of FAM and SYBR Green I overlap completely, so the fluorescence signal of system will be significantly enhanced. Thus, highly sensitive fluorescence quantitative detection for DNA can be realized. Under the optimum conditions, the total fluorescence intensity of FAM and SYBR Green I exhibits good linear dependence on concentration of targets DNA in the range from 2×10(-11) to 2.5×10(-9)M. The detection limit of target DNA is estimated to be 9×10(-12)M (3σ). Compared with previously reported methods of detection DNA with MB, the proposed method can significantly enhance the detection sensitivity.

  6. Combined system for high-time-resolution dual-excitation fluorescence photometry and fluorescence imaging of calcium transients in single normal and diseased skeletal muscle fibers

    NASA Astrophysics Data System (ADS)

    Uttenweiler, Dietmar; Wojciechowski, Reinhold; Makabe, Makoto; Veigel, Claudia; Fink, Rainer H.

    1994-12-01

    Fast photometric measurements and video-imaging of fluorescent indicators both are powerful tools in measuring the intracellular free calcium concentration of muscle and many other cells. as photometric systems yield a high temporal resolution, calcium imaging systems have high spatial but significantly reduced temporal resolution. Therefore we have developed an integrated system combining both methods and based mostly on standard components. As a common, sensitive Ca2+- indicator we used the fluorescent probe Fura-2, which is alternatingly excited for ratio measurements at 340/380 nm. We used a commercially available dual excitation photometric system (OSP-3; Olympus) for attaching a CCD-camera and a frame grabber board. To achieve the synchronization we had to design circuitries for external triggering, synchronization and accurate control of the filter changer, which we added to the system. Additionally, the software for a triggered image acquisition was developed. With this integrated setup one can easily switch between the fast photometric mode (ratio frequency 100 Hz) and the imaging mode (ratio frequency 4.17 Hz). The calcium images are correlated with the 25 times faster spot measurements and are analyzed by means of image processing. With this combined system we study release and uptake of calcium ions of normal and diseased skeletal muscle from mdx mice. Such a system will also be important for other cellular studies in which fluorescence indicators are used to monitor similar time dependent alterations as well as changes in cellular distributions of calcium.

  7. Improved Diffuse Fluorescence Flow Cytometer Prototype for High Sensitivity Detection of Rare Circulating Cells In Vivo

    NASA Astrophysics Data System (ADS)

    Pestana, Noah Benjamin

    Accurate quantification of circulating cell populations is important in many areas of pre-clinical and clinical biomedical research, for example, in the study of cancer metastasis or the immune response following tissue and organ transplants. Normally this is done "ex-vivo" by drawing and purifying a small volume of blood and then analyzing it with flow cytometry, hemocytometry or microfludic devices, but the sensitivity of these techniques are poor and the process of handling samples has been shown to affect cell viability and behavior. More recently "in vivo flow cytometry" (IVFC) techniques have been developed where fluorescently-labeled cells flowing in a small blood vessel in the ear or retina are analyzed, but the sensitivity is generally poor due to the small sampling volume. To address this, our group recently developed a method known as "Diffuse Fluorescence Flow Cytometry" (DFFC) that allows detection and counting of rare circulating cells with diffuse photons, offering extremely high single cell counting sensitivity. In this thesis, an improved DFFC prototype was designed and validated. The chief improvements were three-fold, i) improved optical collection efficiency, ii) improved detection electronics, and iii) development of a method to mitigate motion artifacts during in vivo measurements. In combination, these improvements yielded an overall instrument detection sensitivity better than 1 cell/mL in vivo, which is the most sensitive IVFC system reported to date. Second, development and validation of a low-cost microfluidic device reader for analysis of ocular fluids is described. We demonstrate that this device has equivalent or better sensitivity and accuracy compared a fluorescence microscope, but at an order-of-magnitude reduced cost with simplified operation. Future improvements to both instruments are also discussed.

  8. Deriving chlorophyll fluorescence emissions of vegetation canopies from high resolution field reflectance spectra

    NASA Astrophysics Data System (ADS)

    Middleton, Elizabeth M.; Corp, Lawrence A.; Daughtry, Craig S.; Entcheva Campbell, Petya K.; Butcher, L. Maryn

    2005-11-01

    Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll fluorescence (ChlF) peaks centered at 685 nm and 735 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SIF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops and small tree plots of three deciduous species (red maple, tulip poplar, sweet gum). Leaf level measurements were also made of foliage which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and nitrogen (N) contents). As part of ongoing experiments, measurements were made on N application plots within corn (280, 140, 70, and 0 kg N/ha) and tree (0, 37.5, 75, 112.5, 150 kg N /ha) sites at the USDA/Agriculture Research Service in Beltsville, MD. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrow- band regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red SIF ratio (SIFratio) derived from these field reflectance spectra successfully discriminated foliar pigment ratios altered by N application rates in both corn crops. This ratio was also positively correlated to the C/N ratio at leaf and canopy levels, for the available corn data (e.g., 2004). No consistent N treatment or species differences in SIF were detected in the tree foliage, but additional 2005 data are forthcoming. This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

  9. A fluorescence reagent for the highly selective recognition and separation of lead ion (II) from aqueous solutions.

    PubMed

    Ma, Li-Jun; Yan, Yuhua; Chen, Liping; Cao, Weiguang; Li, Hongwei; Yang, Liting; Wu, Yuqing

    2012-11-02

    A new fluorescence reagent, N,N-bi[4(1-pyrene)-butyroyl]-lysine (1) was synthesized. The new fluorescence sensor showed high sensitivity (detection limit up to 20.7 μg L(-1)) and specific selectivity for Pb(2+) over other metal ions examined in aqueous solutions. It could also be used to remove Pb(2+) from aqueous solutions by filtering the insoluble 1-Pb(2+) complex with sufficient reversibility.

  10. Saturated fluorescence measurements of the hydroxyl radical in laminar high-pressure flames

    NASA Technical Reports Server (NTRS)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.

    1990-01-01

    The efficacy of laser saturated fluorescence (LSF) for OH concentration measurements in high pressure flames was studied theoretically and experimentally. Using a numerical model describing the interaction of hydroxyl with nonuniform laser excitation, the effect of pressure on the validity of the balanced cross-rate model was studied along with the sensitivity of the depopulation of the laser-coupled levels to the ratio of rate coefficients describing: (1) electronic quenching to (sup 2) Sigma (+) (v double prime greater than 0), and (2) vibrational relaxation from v double prime greater than 0 to v double prime = 0. At sufficiently high pressures and near-saturated conditions, the total population of the laser-coupled levels reaches an asymptotic value, which is insensitive to the degree of saturation. When the ratio of electronic quenching to vibrational relaxation is small and the rate of coefficients for rotational transfer in the ground and excited electronic states are nearly the same, the balanced cross-rate model remains a good approximation for all pressures. When the above ratio is large, depopulation of the laser-coupled levels becomes significant at high pressures, and thus the balanced cross-rate model no longer holds. Under these conditions, however, knowledge of the depletion of the laser-coupled levels can be used to correct the model. A combustion facility for operation up to 20 atm was developed to allow LSF measurements of OH in high pressure flames. Using this facility, partial saturation in laminar high pressure (less than or equal to 12.3 atm) C2H6/O2/N2 flames was achieved. To evaluate the limits of the balanced cross-rate model, absorption and calibrated LSF measurements at 3.1 and 6.1 atm were compared. The fluorescence voltages were calibrated with absorption measurements in an atmospheric flame and corrected for their finite sensitivity to quenching with: (1) estimated quenching rate coefficients, and (2) an in situ measurement from a

  11. Consensus and future directions on the definition of high on-treatment platelet reactivity to adenosine diphosphate.

    PubMed

    Bonello, Laurent; Tantry, Udaya S; Marcucci, Rossella; Blindt, Ruediger; Angiolillo, Dominick J; Becker, Richard; Bhatt, Deepak L; Cattaneo, Marco; Collet, Jean Philippe; Cuisset, Thomas; Gachet, Christian; Montalescot, Gilles; Jennings, Lisa K; Kereiakes, Dean; Sibbing, Dirk; Trenk, Dietmar; Van Werkum, Jochem W; Paganelli, Franck; Price, Matthew J; Waksman, Ron; Gurbel, Paul A

    2010-09-14

    The addition of clopidogrel to aspirin treatment reduces ischemic events in a wide range of patients with cardiovascular disease. However, recurrent ischemic event occurrence during dual antiplatelet therapy, including stent thrombosis, remains a major concern. Platelet function measurements during clopidogrel treatment demonstrated a variable and overall modest level of P2Y(12) inhibition. High on-treatment platelet reactivity to adenosine diphosphate (ADP) was observed in selected patients. Multiple studies have now demonstrated a clear association between high on-treatment platelet reactivity to ADP measured by multiple methods and adverse clinical event occurrence. However, the routine measurement of platelet reactivity has not been widely implemented and recommended in the guidelines. Reasons for the latter include: 1) a lack of consensus on the optimal method to quantify high on-treatment platelet reactivity and the cutoff value associated with clinical risk; and 2) limited data to support that alteration of therapy based on platelet function measurements actually improves outcomes. This review provides a consensus opinion on the definition of high on-treatment platelet reactivity to ADP based on various methods reported in the literature and proposes how this measurement may be used in the future care of patients.

  12. Coumarin-based 'turn-off' fluorescent chemosensor with high selectivity for Cu2+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Jun; Qi, De-Qiang; You, Jin-Zong; Hu, Fei-Fei; Bian, Jia-Ying; Yang, Chun-Xia; Huang, Juan

    2015-07-01

    Coumarin-based "turn-off" fluorescent chemosensor, 3-acetoacetyl-7-diethylaminocoumarin (1), has been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. The fluorescence behaviors in the presence of various metal ions were investigated in aqueous media. 1 Exhibits highly selective and sensitive absorbance and fluorescence sensing ability for Cu2+ over other metal ions. Addition of Cu2+ to the aqueous solution of 1 gave rise to obvious absorbance change and fluorescence quenching. Other competing ions, such as Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Pb2+, Cd2+, Hg2+, induced negligible absorbance and fluorescence changes under the same conditions. The job's plot showed that the stoichiometry between 1 and Cu2+ was estimated to be 1:1. The fluorescence intensity varied almost linearly vs. the concentration of Cu2+ (1.0-7.0 μM), and the detection limit of Cu2+ was estimated to be 1.81 nM, indicating that 1 can be used as "turn-off" fluorescent chemosensor to selectively detect Cu2+ in aqueous solution.

  13. Highly selective fluorescent chemosensor for detection of Fe3+ based on Fe3O4@ZnO

    PubMed Central

    Li, Jingshuai; Wang, Qi; Guo, Zhankui; Ma, Hongmin; Zhang, Yong; Wang, Bing; Bin, Du; Wei, Qin

    2016-01-01

    The combination of fluorescent nanoparticles and specific molecular probes appears to be a promising strategy for developing fluorescent nanoprobes. In this work, L-cysteine (L-Cys) capped Fe3O4@ZnO core-shell nanoparticles were synthesized for the highly selective detection of Fe3+. The proposed nanoprobe shows excellent fluorescent property and high selectivity for Fe3+ due to the binding affinity of L-Cys with Fe3+. The binding of Fe3+ to the nanoprobe induces an apparent decrease of the fluorescence. Thus a highly selective fluorescent chemosensor for Fe3+ was proposed based on Fe3O4@ZnO nanoprobe. The magnetism of the nanoprobe enables the facile separation of bound Fe3+ from the sample solution with an external magnetic field, which effectively reduces the interference of matrix. The detection limit was 3 nmol L−1 with a rapid response time of less than 1 min. The proposed method was applied to detect Fe3+ in both serum and wastewater samples with acceptable performance. All above features indicated that the proposed fluorescent probe as sensing platform held great potential in applications of biological and analytical field. PMID:27000972

  14. A carbon dot-based "off-on" fluorescent probe for highly selective and sensitive detection of phytic acid.

    PubMed

    Gao, Zhao; Wang, Libing; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2015-08-15

    We herein report a facile, one-step pyrolysis synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and lysine as the surface passivation reagent. The as-prepared CDs show narrow size distribution, excellent blue fluorescence and good photo-stability and water dispersivity. The fluorescence of the CDs was found to be effectively quenched by ferric (Fe(III)) ions with high selectivity via a photo-induced electron transfer (PET) process. Upon addition of phytic acid (PA) to the CDs/Fe(III) complex dispersion, the fluorescence of the CDs was significantly recovered, arising from the release of Fe(III) ions from the CDs/Fe(III) complex because PA has a higher affinity for Fe(III) ions compared to CDs. Furthermore, we developed an "off-on" fluorescence assay method for the detection of phytic acid using CDs/Fe(III) as a fluorescent probe. This probe enables the selective detection of PA with a linear range of 0.68-18.69 μM and a limit of detection (signal-to-noise ratio is 3) of 0.36 μM. The assay method demonstrates high selectivity, repeatability, stability and recovery ratio in the detection of the standard and real PA samples. We believe that the facile operation, low-cost, high sensitivity and selectivity render this CD-based "off-on" fluorescent probe an ideal sensing platform for the detection of PA.

  15. Detection of ultra-high energy cosmic ray showers with a single-pixel fluorescence telescope

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Malacari, M.; Bertaina, M.; Casolino, M.; Dawson, B.; Horvath, P.; Hrabovsky, M.; Jiang, J.; Mandat, D.; Matalon, A.; Matthews, J. N.; Motloch, P.; Palatka, M.; Pech, M.; Privitera, P.; Schovanek, P.; Takizawa, Y.; Thomas, S. B.; Travnicek, P.; Yamazaki, K.

    2016-02-01

    We present a concept for large-area, low-cost detection of ultra-high energy cosmic rays (UHECRs) with a Fluorescence detector Array of Single-pixel Telescopes (FAST), addressing the requirements for the next generation of UHECR experiments. In the FAST design, a large field of view is covered by a few pixels at the focal plane of a mirror or Fresnel lens. We report first results of a FAST prototype installed at the Telescope Array site, consisting of a single 200 mm photomultiplier tube at the focal plane of a 1 m2 Fresnel lens system taken from the prototype of the JEM-EUSO experiment. The FAST prototype took data for 19 nights, demonstrating remarkable operational stability. We detected laser shots at distances of several kilometers as well as 16 highly significant UHECR shower candidates.

  16. Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter

    SciTech Connect

    Wada, Yoshimasa; Kubo, Shosei; Suzuki, Katsuaki; Kaji, Hironori; Shizu, Katsuyuki; Tanaka, Hiroyuki; Adachi, Chihaya

    2015-11-02

    We developed a thermally activated delayed fluorescence (TADF) emitter, 2,4,6-tris(4-(9,9-dimethylacridan-10-yl)phenyl)-1,3,5-triazine (3ACR-TRZ), suitable for use in solution-processed organic light-emitting diodes (OLEDs). When doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host at 16 wt. %, 3ACR-TRZ showed a high photoluminescence quantum yield of 98%. Transient photoluminescence decay measurements of the 16 wt. % 3ACR-TRZ:CBP film confirmed that 3ACR-TRZ exhibits efficient TADF with a triplet-to-light conversion efficiency of 96%. This high conversion efficiency makes 3ACR-TRZ attractive as an emitting dopant in OLEDs. Using 3ACR-TRZ as an emitter, we fabricated a solution-processed OLED exhibiting a maximum external quantum efficiency of 18.6%.

  17. High resolution laser induced fluorescence Doppler velocimetry utilizing saturated absorption spectroscopy

    SciTech Connect

    Aramaki, Mitsutoshi; Ogiwara, Kohei; Etoh, Shuzo; Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2009-05-15

    A high resolution laser induced fluorescence (LIF) system has been developed to measure the flow velocity field of neutral particles in an electron-cyclotron-resonance argon plasma. The flow velocity has been determined by the Doppler shift of the LIF spectrum, which is proportional to the velocity distribution function. Very high accuracy in velocity determination has been achieved by installing a saturated absorption spectroscopy unit into the LIF system, where the absolute value and scale of laser wavelength are determined by using the Lamb dip and the fringes of a Fabry-Perot interferometer. The minimum detectable flow velocity of a newly developed LIF system is {+-}2 m/s, and this performance remains unchanged in a long-time experiment. From the radial measurements of LIF spectra of argon metastable atoms, it is found that there exists an inward flow of neutral particles associated with neutral depletion.

  18. Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance Spectra

    NASA Technical Reports Server (NTRS)

    Middleton, E. M.; Corp, L. A.; Daughtry, C. S. T.; Campbell, P. K. Entcheva

    2006-01-01

    A two-year experiment was performed on corn (Zea mays L.) crops under nitrogen (N) fertilization regimes to examine the use of hyperspectral canopy reflectance information for estimating chlorophyll fluorescence (ChlF) and vegetation production. Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll ChlF peaks centered at 685V10 nm and 735V5 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops, as part of an ongoing multi-year experiment at the USDA/Agriculture Research Service in Beltsville, MD. A spectroradiometer (ASD-FR Fieldspec Pro, Analytical Spectral Devices, Inc., Boulder, CO) was used to measure canopy radiances 1 m above plant canopies with a 22deg field of view and a 0deg nadir view zenith angle. Canopy and plant measurements were made at the R3 grain fill reproductive stage on 3-4 replicate N application plots provided seasonal inputs of 280, 140, 70, and 28 kg N/ha. Leaf level measurements were also made which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and N contents). Crop yields were determined at harvest. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrowband regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red S F ratio derived from these field reflectance spectra successfully discriminated foliar pigment levels (e.g., total chlorophyll, Chl) associated with N application rates in both corn crops. This canopy-level spectral ratio was also

  19. ET-1 increases reactive oxygen species following hypoxia and high salt diet in the mouse glomerulus

    PubMed Central

    Heimlich, J. Brett; Speed, Joshua S.; Bloom, Christopher J.; O'Connor, Paul M.; Pollock, Jennifer S.; Pollock, David M.

    2014-01-01

    Aim The current study was designed to determine whether ET-1 derived from endothelial cells contributes to oxidative stress in the glomerulus of mice subjected to a high salt diet and/or hypoxia. Methods C57BL6/J control mice or vascular endothelial cell ET-1 knockout (VEET KO) mice were subjected to three-hour exposure to hypoxia (8% O2) and or 2 weeks of high salt diet (4% NaCl) prior to metabolic cage assessment of renal function and isolation of glomeruli for determination of reactive oxygen species (ROS). Results In control mice, hypoxia significantly increased urinary protein excretion during the initial 24 hrs, but only in animals on a high salt diet. Hypoxia increased glomerular ET-1 mRNA expression in control, but not in vascular endothelial cell ET-1 knockout (VEET KO) mice. Under normoxic conditions, mice on a high salt diet had approximately 150% higher glomerular ET-1 mRNA expression compared to a normal salt diet (p<0.05). High salt diet administration significantly increased glomerular ROS production in flox control, but not in glomeruli isolated from VEET KO mice. In C57BL6/J mice, the ETA receptor selective antagonist, ABT-627, significantly attenuated the increase in glomerular ROS production produced by high salt diet. In addition, chronic infusion of C57BL6/J mice with a sub-pressor dose of ET-1 (osmotic pumps) significantly increased levels of glomerular ROS that were prevented by ETA antagonist treatment. Conclusion These data suggest that both hypoxia and a high salt diet increases glomerular ROS production via endothelial derived ET-1-ETA receptor activation and provide a potential mechanism for ET-1 induced nephropathy. PMID:25219340

  20. High resolution X-ray fluorescence imaging for a microbeam radiation therapy treatment planning system

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Inscoe, Christina; Burk, Laurel; Ger, Rachel; Yuan, Hong; Lu, Jianping; Chang, Sha; Zhou, Otto

    2014-03-01

    Microbeam radiation therapy (MRT) uses an array of high-dose, narrow (~100 μm) beams separated by a fraction of a millimeter to treat various radio-resistant, deep-seated tumors. MRT has been shown to spare normal tissue up to 1000 Gy of entrance dose while still being highly tumoricidal. Current methods of tumor localization for our MRT treatments require MRI and X-ray imaging with subject motion and image registration that contribute to the measurement error. The purpose of this study is to develop a novel form of imaging to quickly and accurately assist in high resolution target positioning for MRT treatments using X-ray fluorescence (XRF). The key to this method is using the microbeam to both treat and image. High Z contrast media is injected into the phantom or blood pool of the subject prior to imaging. Using a collimated spectrum analyzer, the region of interest is scanned through the MRT beam and the fluorescence signal is recorded for each slice. The signal can be processed to show vascular differences in the tissue and isolate tumor regions. Using the radiation therapy source as the imaging source, repositioning and registration errors are eliminated. A phantom study showed that a spatial resolution of a fraction of microbeam width can be achieved by precision translation of the mouse stage. Preliminary results from an animal study showed accurate iodine profusion, confirmed by CT. The proposed image guidance method, using XRF to locate and ablate tumors, can be used as a fast and accurate MRT treatment planning system.

  1. The exceptionally high reactivity of Cys 621 is critical for electrophilic activation of the sensory nerve ion channel TRPA1.

    PubMed

    Bahia, Parmvir K; Parks, Thomas A; Stanford, Katherine R; Mitchell, David A; Varma, Sameer; Stevens, Stanley M; Taylor-Clark, Thomas E

    2016-06-01

    Activation of the sensory nerve ion channel TRPA1 by electrophiles is the key mechanism that initiates nociceptive signaling, and leads to defensive reflexes and avoidance behaviors, during oxidative stress in mammals. TRPA1 is rapidly activated by subtoxic levels of electrophiles, but it is unclear how TRPA1 outcompetes cellular antioxidants that protect cytosolic proteins from electrophiles. Here, using physiologically relevant exposures, we demonstrate that electrophiles react with cysteine residues on mammalian TRPA1 at rates that exceed the reactivity of typical cysteines by 6,000-fold and that also exceed the reactivity of antioxidant enzymes. We show that TRPA1 possesses a complex reactive cysteine profile in which C621 is necessary for electrophile-induced binding and activation. Modeling of deprotonation energies suggests that K620 contributes to C621 reactivity and mutation of K620 alone greatly reduces the effect of electrophiles on TRPA1. Nevertheless, binding of electrophiles to C621 is not sufficient for activation, which also depends on the function of another reactive cysteine (C665). Together, our results demonstrate that TRPA1 acts as an effective electrophilic sensor because of the exceptionally high reactivity of C621.

  2. The exceptionally high reactivity of Cys 621 is critical for electrophilic activation of the sensory nerve ion channel TRPA1

    PubMed Central

    Bahia, Parmvir K.; Parks, Thomas A.; Stanford, Katherine R.; Mitchell, David A.; Varma, Sameer; Stevens, Stanley M.

    2016-01-01

    Activation of the sensory nerve ion channel TRPA1 by electrophiles is the key mechanism that initiates nociceptive signaling, and leads to defensive reflexes and avoidance behaviors, during oxidative stress in mammals. TRPA1 is rapidly activated by subtoxic levels of electrophiles, but it is unclear how TRPA1 outcompetes cellular antioxidants that protect cytosolic proteins from electrophiles. Here, using physiologically relevant exposures, we demonstrate that electrophiles react with cysteine residues on mammalian TRPA1 at rates that exceed the reactivity of typical cysteines by 6,000-fold and that also exceed the reactivity of antioxidant enzymes. We show that TRPA1 possesses a complex reactive cysteine profile in which C621 is necessary for electrophile-induced binding and activation. Modeling of deprotonation energies suggests that K620 contributes to C621 reactivity and mutation of K620 alone greatly reduces the effect of electrophiles on TRPA1. Nevertheless, binding of electrophiles to C621 is not sufficient for activation, which also depends on the function of another reactive cysteine (C665). Together, our results demonstrate that TRPA1 acts as an effective electrophilic sensor because of the exceptionally high reactivity of C621. PMID:27241698

  3. [Cardiovascular reactivity to emotional texts in subjects with low and high level of psychoticism].

    PubMed

    Lysenko, N E; Davydov, D M

    2011-01-01

    The article presents the results of comparative study of groups of subjects with low and high level of psychoticism. Heart rate, heart rate responses to inspiratory and expiratory Valsalva maneuvers, and blood pressure were measured before and after presentation of the texts with validated negative content in groups of subjects with low and high psychoticism scores. It was hypothesized that subjects with high level of psychoticism would be less engaged in the processing of negative contents of the texts and their physiological reactivity (physiological resources submitted for support of cognitive processing) would be less pronounced compared to subjects with low level of psychoticism. Significant main effect of psychoticism was obtained for changes in heart rate to expiratory Valsalva maneuver after presentations of the texts. Significant interaction effects of gender and psychoticism were obtained for systolic blood pressure. Other cardiovascular variables were not sensitive to the level of psychoticism. These effects of psychoticism were independent of other individual traits, such as neuroticism, extraversion, lie (social desirability), anger, trait anxiety and depression.

  4. 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.

  5. Highly efficient electrochemical generation of fluorescent intramolecular charge-transfer states

    NASA Astrophysics Data System (ADS)

    Kapturkiewicz, Andrzej; Herbich, Jerzy; Nowacki, Jacek

    1997-08-01

    The electrochemically generated chemiluminescence of 4-(3,6-di-tert-butylcarbazol-9-yl)-benzonitrile (CBP) and 3,6-di-tert-butylcarbazol-9-yl- terephthalonitrile (CTO) was studied using the triple-potential-step method. In the electrogenerated emission spectra the charge-transfer (CT) bands (the same as in photoluminescence) were observed. The Feldberg plot analysis indicates that the 1,3CT states are formed directly by the electron transfer between the radical anion and cation. High emission efficiencies (0.027 for CBP and 0.011 for CTO) were found with population yields of the fluorescent state markedly different for both compounds (0.066 for CBP and unusually large, 0.64 for CTO). Evidence is also presented that at low temperatures the efficiency of the fluorescent state formation (for CTO) is still higher, approaching unity. This finding is interpreted in terms of the different electronic structure of the lowest excited triplet states of the two compounds.

  6. High Resolution Fluorescence Imaging of Cancers Using Lanthanide Ion-Doped Upconverting Nanocrystals

    PubMed Central

    Naccache, Rafik; Rodríguez, Emma Martín; Bogdan, Nicoleta; Sanz-Rodríguez, Francisco; de la Cruz, Maria del Carmen Iglesias; de la Fuente, Ángeles Juarranz; Vetrone, Fiorenzo; Jaque, Daniel; Solé, José García; Capobianco, John A.

    2012-01-01

    During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR) excitation (in the biological window) have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs) and metal nanoparticles, mostly gold nanorods (GNRs), are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide) ions: The excited donor ions (usually Yb3+ ion) that absorb the NIR excitation and the acceptor ions (usually Er3+, Ho3+ or Tm3+), that are responsible for the emitted visible (or also near infrared) radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to “in vitro” and “in vivo” cancer imaging, selective targeting and treatment are examined in this review. PMID:24213500

  7. A fast, low cost, and highly efficient fluorescent DNA labeling method using methyl green.

    PubMed

    Prieto, Daniel; Aparicio, Gonzalo; Morande, Pablo E; Zolessi, Flavio R

    2014-09-01

    The increasing need for multiple-labeling of cells and whole organisms for fluorescence microscopy has led to the development of hundreds of fluorophores that either directly recognize target molecules or organelles, or are attached to antibodies or other molecular probes. DNA labeling is essential to study nuclear-chromosomal structure, as well as for gel staining, but also as a usual counterstain in immunofluorescence, FISH or cytometry. However, there are currently few reliable red to far-red-emitting DNA stains that can be used. We describe herein an extremely simple, inexpensive and robust method for DNA labeling of cells and electrophoretic gels using the very well-known histological stain methyl green (MG). MG used in very low concentrations at physiological pH proved to have relatively narrow excitation and emission spectra, with peaks at 633 and 677 nm, respectively, and a very high resistance to photobleaching. It can be used in combination with other common DNA stains or antibodies without any visible interference or bleed-through. In electrophoretic gels, MG also labeled DNA in a similar way to ethidium bromide, but, as expected, it did not label RNA. Moreover, we show here that MG fluorescence can be used as a stain for direct measuring of viability by both microscopy and flow cytometry, with full correlation to ethidium bromide staining. MG is thus a very convenient alternative to currently used red-emitting DNA stains.

  8. A high-throughput fluorescence-based assay for Plasmodium dihydroorotate dehydrogenase inhibitor screening.

    PubMed

    Caballero, Iván; Lafuente, María José; Gamo, Francisco-Javier; Cid, Concepción

    2016-08-01

    Plasmodium dihydroorotate dehydrogenase (DHODH) is a mitochondrial membrane-associated flavoenzyme that catalyzes the rate-limiting step of de novo pyrimidine biosynthesis. DHODH is a validated target for malaria, and DSM265, a potent inhibitor, is currently in clinical trials. The enzyme catalyzes the oxidation of dihydroorotate to orotate using flavin mononucleotide (FMN) as cofactor in the first half of the reaction. Reoxidation of FMN to regenerate the active enzyme is mediated by ubiquinone (CoQD), which is the physiological final electron acceptor and second substrate of the reaction. We have developed a fluorescence-based high-throughput enzymatic assay to find DHODH inhibitors. In this assay, the CoQD has been replaced by a redox-sensitive fluorogenic dye, resazurin, which changes to a fluorescent state on reduction to resorufin. Remarkably, the assay sensitivity to find competitive inhibitors of the second substrate is higher than that reported for the standard colorimetric assay. It is amenable to 1536-well plates with Z' values close to 0.8. The fact that the human enzyme can also be assayed in the same format opens additional applications of this assay to the discovery of inhibitors to treat cancer, transplant rejection, autoimmune diseases, and other diseases mediated by rapid cellular growth.

  9. Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

    NASA Astrophysics Data System (ADS)

    Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

    2011-03-01

    A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

  10. Strategy for high recovery of fluorescence from quencher assembled quantum-dot donor

    NASA Astrophysics Data System (ADS)

    Kim, Joong Hyun; Ozkan, Mihrimah

    2014-05-01

    We fabricated 1.4 nm nanogold and molecular dark quencher assembled quantum dot for estimating their performances in a target specific conformal changing molecular event. For the assembling, we immobilized each acceptor linked molecular beacons using interaction between biotin at molecular beacon and streptavidins on quantum dot. Through optical analysis of the purified hybrids of the acceptors and quantum dots, we could estimate numbers of the assembled acceptors per quantum dot and their efficiency of energy transfer depending on conformal changes of molecular beacons. We obtained maximum 95 % and 78% of energy transfer efficiency with 17 metallic nanocrystals and 41 black hole quencher 2, the molecular dark quencher per single quantum dote, respectively. Molecular beacons form linear helix from a hair-pin structure by hybridizing with complementary DNA. In the presence of target DNA, energy transfer efficiency of the organic quencher was 22 % while only 2 % decreased efficiency was obtained with the nanogold, indicating higher fluorescence recovery with the ordinary organic quencher. Considering the relatively low assembled number and the large size, a steric hindrance might be attributed to the low fluorescence recovery. Since the energy transfer efficiency obtained with the nanogold at a fixed distance is high enough, it would be still effective to apply nanogold a system, where nanogold is removed permanently from quantum dots.

  11. High performance magnesium anode in paper-based microfluidic battery, powering on-chip fluorescence assay

    PubMed Central

    Koo, Youngmi; Sankar, Jagannathan; Yun, Yeoheung

    2014-01-01

    A high power density and long-lasting stable/disposable magnesium battery anode was explored for a paper-based fluidic battery to power on-chip functions of various Point of Care (POC) devices. The single galvanic cell with magnesium foil anode and silver foil cathode in Origami cellulose chip provided open circuit potential, 2.2 V, and power density, 3.0 mW/cm2. A paper-based fluidic galvanic cell was operated with one drop of water (80 μl) and continued to run until it was dry. To prove the concept about powering on-chip POC devices, two-serial galvanic cells are developed and incorporated with a UV-light emitting diode (λ = 365 nm) and fluorescence assay for alkaline phosphatase reaction. Further, detection using smart phones was performed for quantitative measurement of fluorescent density. To conclude, a magnesium-based fluidic battery paper chip was extremely low-cost, required minute sample volumes, was easy to dispose of, light weight, easy to stack, store and transport, easy to fabricate, scalable, and has faster analysis times. PMID:25332741

  12. Open Source High Content Analysis Utilizing Automated Fluorescence Lifetime Imaging Microscopy

    PubMed Central

    Warren, Sean C.; Alibhai, Dominic; West, Lucien; Kumar, Sunil; Alexandrov, Yuriy; Munro, Ian; Garcia, Edwin; McGinty, James; Talbot, Clifford; Serwa, Remigiusz A.; Thinon, Emmanuelle; da Paola, Vincenzo; Murray, Edward J.; Stuhmeier, Frank; Neil, Mark A. A.; Tate, Edward W.; Dunsby, Christopher; French, Paul M. W.

    2017-01-01

    We present an open source high content analysis instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions using Förster resonance energy transfer (FRET) based readouts of fixed or live cells in multiwell plates. This provides a means to screen for cell signaling processes read out using intramolecular FRET biosensors or intermolecular FRET of protein interactions such as oligomerization or heterodimerization, which can be used to identify binding partners. We describe here the functionality of this automated multiwell plate FLIM instrumentation and present exemplar data from our studies of HIV Gag protein oligomerization and a time course of a FRET biosensor in live cells. A detailed description of the practical implementation is then provided with reference to a list of hardware components and a description of the open source data acquisition software written in µManager. The application of FLIMfit, an open source MATLAB-based client for the OMERO platform, to analyze arrays of multiwell plate FLIM data is also presented. The protocols for imaging fixed and live cells are outlined and a demonstration of an automated multiwell plate FLIM experiment using cells expressing fluorescent protein-based FRET constructs is presented. This is complemented by a walk-through of the data analysis for this specific FLIM FRET data set. PMID:28190060

  13. Highly stable antibacterial silver nanoparticles as selective fluorescent sensor for Fe³⁺ ions.

    PubMed

    Makwana, Bharat A; Vyas, Disha J; Bhatt, Keyur D; Jain, Vinod K; Agrawal, Yadvendra K

    2015-01-05

    Calix[4]resorcinarene polyhydrazide (CPH) protected water dispersible fluorescent silver nanaoparticles (AgNps) were prepared by one-pot method using water soluble CPH and AgNO₃. (CPH) bearing hydrazide group on its periphery acts as a reducing agent and its web type of structure as a stabilizing agent for the formation of calix protected silver nanoparticles (CPH-AgNps). CPH-AgNps were found to be highly stable over 120 days at room temperature and at varied pH. CPH-AgNps were characterized by UV/Vis-spectroscopy, particle size analyzer (PSA), transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). Duly characterized nanoparticles were explored for their application as sensitive and selective fluorescent chemosensors for various metal ions. It was found that nanoparticles were selective and sensitive only for Fe(3+) ions with the linear range of detection from 0.1 μM to 10 μM. CPH-AgNps were also found to exhibit good antimicrobial activity when compared with standard Chloramphenicol. The selectivity and antimicrobial activity of CPH-AgNps suggests its potential use as a sensor for Fe(III) ions in ecosystems prone to industrial pollution and as an antimicrobial agent in biological applications.

  14. [Determination of peroxides in environmental samples by high performance liquid chromatography with fluorescence detection].

    PubMed

    Xu, Jinrong; Chen, Zhongming

    2005-07-01

    A high performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the determination of hydrogen peroxide and organic peroxides in environmental samples, and the method has been applied to peroxides detection in urban air and rain samples. The analytical sensitivity was improved. Post-column derivatization involved the oxidation of peroxides to a fluorescent dimer using p-hydroxyphenylacetic acid, a reaction catalyzed by hemin. The optimal excitation wavelength was 315 nm, while the emission wavelength was 400 nm. The temperature of the reaction coil was controlled at about 30 degrees C. Based on the ratio of signal to noise of 3, the detection limits were 4.0 x 10(-9) mol/L for hydroperoxide (H2O2), 4.1 x 10(-8) mol/L for methylhydroperoxide (MHP) and 6.7 x 10(-8) mol/L for ethylhydroperoxide (EHP) for aqueous samples. While the corresponding detection limits were 2.4 ng/m3 for H2O2, 35.2 ng/m3 for MHP, and 74.4 ng/m3 for EHP for air samples. Air samples were collected by Horibe cold trap at the temperature of about -90 degrees C. The results show that H2O2, hydroxymethyl hydroperoxide (HMHP), MHP, and EHP were the major peroxides in air, and that peroxyacetic acid (PAA) was occasionally detected. In rain samples, the two major peroxides were H2O2 and HMHP.

  15. Fluorescent-Protein Stabilization and High-Resolution Imaging of Cleared, Intact Mouse Brains

    PubMed Central

    Schwarz, Martin K.; Scherbarth, Annemarie; Sprengel, Rolf; Engelhardt, Johann; Theer, Patrick; Giese, Guenter

    2015-01-01

    In order to observe and quantify long-range neuronal connections in intact mouse brain by light microscopy, it is first necessary to clear the brain, thus suppressing refractive-index variations. Here we describe a method that clears the brain and preserves the signal from proteinaceous fluorophores using a pH-adjusted non-aqueous index-matching medium. Successful clearing is enabled through the use of either 1-propanol or tert-butanol during dehydration whilst maintaining a basic pH. We show that high-resolution fluorescence imaging of entire, structurally intact juvenile and adult mouse brains is possible at subcellular resolution, even following many months in clearing solution. We also show that axonal long-range projections that are EGFP-labelled by modified Rabies virus can be imaged throughout the brain using a purpose-built light-sheet fluorescence microscope. To demonstrate the viability of the technique, we determined a detailed map of the monosynaptic projections onto a target cell population in the lateral entorhinal cortex. This example demonstrates that our method permits the quantification of whole-brain connectivity patterns at the subcellular level in the uncut brain. PMID:25993380

  16. A new hydroxynaphthyl benzothiazole derived fluorescent probe for highly selective and sensitive Cu2 + detection

    NASA Astrophysics Data System (ADS)

    Tang, Lijun; He, Ping; Zhong, Keli; Hou, Shuhua; Bian, Yanjiang

    2016-12-01

    A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu2 + in DMSO/H2O (7/3, v/v, Tris-HCl 10 mM, pH = 7.4) solution based on Cu2 + catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205 min- 1. Moreover, application of BTNP to Cu2 + detection in living cells and real water samples was also explored.

  17. Blueberry intervention improves vascular reactivity and lowers blood pressure in high-fat-, high-cholesterol-fed rats.

    PubMed

    Rodriguez-Mateos, Ana; Ishisaka, Akari; Mawatari, Kazuaki; Vidal-Diez, Alberto; Spencer, Jeremy P E; Terao, Junji

    2013-05-28

    Growing evidence suggests that intake of flavonoid-containing foods may exert cardiovascular benefits in human subjects. We have investigated the effects of a 10-week blueberry (BB) supplementation on blood pressure (BP) and vascular reactivity in rats fed a high-fat/high-cholesterol diet, known to induce endothelial dysfunction. Rats were randomly assigned to follow a control chow diet, a chow diet supplemented with 2 % (w/w) BB, a high-fat diet (10 % lard; 0·5 % cholesterol) or the high fat plus BB for 10 weeks. Rats supplemented with BB showed significant reductions in systolic BP (SBP) of 11 and 14 %, at weeks 8 and 10, respectively, relative to rats fed the control chow diet (week 8 SBP: 107·5 (SEM 4·7) v. 122·2 (SEM 2·1) mmHg, P= 0·018; week 10 SBP: 115·0 (SEM 3·1) v. 132·7 (SEM 1·5) mmHg, P< 0·0001). Furthermore, SBP was reduced by 14 % in rats fed with the high fat plus 2 % BB diet at week 10, compared to those on the high-fat diet only (SBP: 118·2 (SEM 3·6) v. 139·5 (SEM 4·5) mmHg, P< 0·0001). Aortas harvested from BB-fed animals exhibited significantly reduced contractile responses (to L-phenylephrine) compared to those fed the control chow or high-fat diets. Furthermore, in rats fed with high fat supplemented with BB, aorta relaxation was significantly greater in response to acetylcholine compared to animals fed with the fat diet. These data suggest that BB consumption can lower BP and improve endothelial dysfunction induced by a high fat, high cholesterol containing diet.

  18. High precision during food recruitment of experienced (reactivated) foragers in the stingless bee Scaptotrigona mexicana (Apidae, Meliponini)

    NASA Astrophysics Data System (ADS)

    Sánchez, Daniel; Nieh, James C.; Hénaut, Yann; Cruz, Leopoldo; Vandame, Rémy

    Several studies have examined the existence of recruitment communication mechanisms in stingless bees. However, the spatial accuracy of location-specific recruitment has not been examined. Moreover, the location-specific recruitment of reactivated foragers, i.e., foragers that have previously experienced the same food source at a different location and time, has not been explicitly examined. However, such foragers may also play a significant role in colony foraging, particularly in small colonies. Here we report that reactivated Scaptotrigona mexicana foragers can recruit with high precision to a specific food location. The recruitment precision of reactivated foragers was evaluated by placing control feeders to the left and the right of the training feeder (direction-precision tests) and between the nest and the training feeder and beyond it (distance-precision tests). Reactivated foragers arrived at the correct location with high precision: 98.44% arrived at the training feeder in the direction trials (five-feeder fan-shaped array, accuracy of at least +/-6° of azimuth at 50 m from the nest), and 88.62% arrived at the training feeder in the distance trials (five-feeder linear array, accuracy of at least +/-5 m or +/-10% at 50 m from the nest). Thus, S. mexicana reactivated foragers can find the indicated food source at a specific distance and direction with high precision, higher than that shown by honeybees, Apis mellifera, which do not communicate food location at such close distances to the nest.

  19. High precision during food recruitment of experienced (reactivated) foragers in the stingless bee Scaptotrigona mexicana (Apidae, Meliponini).

    PubMed

    Sánchez, Daniel; Nieh, James C; Hénaut, Yann; Cruz, Leopoldo; Vandame, Rémy

    2004-07-01

    Several studies have examined the existence of recruitment communication mechanisms in stingless bees. However, the spatial accuracy of location-specific recruitment has not been examined. Moreover, the location-specific recruitment of reactivated foragers, i.e., foragers that have previously experienced the same food source at a different location and time, has not been explicitly examined. However, such foragers may also play a significant role in colony foraging, particularly in small colonies. Here we report that reactivated Scaptotrigona mexicana foragers can recruit with high precision to a specific food location. The recruitment precision of reactivated foragers was evaluated by placing control feeders to the left and the right of the training feeder (direction-precision tests) and between the nest and the training feeder and beyond it (distance-precision tests). Reactivated foragers arrived at the correct location with high precision: 98.44% arrived at the training feeder in the direction trials (five-feeder fan-shaped array, accuracy of at least +/-6 degrees of azimuth at 50 m from the nest), and 88.62% arrived at the training feeder in the distance trials (five-feeder linear array, accuracy of at least +/-5 m or +/-10% at 50 m from the nest). Thus, S. mexicana reactivated foragers can find the indicated food source at a specific distance and direction with high precision, higher than that shown by honeybees, Apis mellifera, which do not communicate food location at such close distances to the nest.

  20. Subunits of highly Fluorescent Protein R-Phycoerythrin as Probes for Cell Imaging and Single-Molecule Detection

    SciTech Connect

    Isailovic, Dragan

    2005-01-01

    The purposes of our research were: (1) To characterize subunits of highly fluorescent protein R-Phycoerythrin (R-PE) and check their suitability for single-molecule detection (SMD) and cell imaging, (2) To extend the use of R-PE subunits through design of similar proteins that will be used as probes for microscopy and spectral imaging in a single cell, and (3) To demonstrate a high-throughput spectral imaging method that will rival spectral flow cytometry in the analysis of individual cells. We first demonstrated that R-PE subunits have spectroscopic and structural characteristics that make them suitable for SMD. Subunits were isolated from R-PE by high-performance liquid chromatography (HPLC) and detected as single molecules by total internal reflection fluorescence microscopy (TIRFM). In addition, R-PE subunits and their enzymatic digests were characterized by several separation and detection methods including HPLC, capillary electrophoresis, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and HPLC-electrospray ionization mass spectrometry (ESI-MS). Favorable absorption and fluorescence of the R-PE subunits and digest peptides originate from phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores that are covalently attached to cysteine residues. High absorption coefficients and strong fluorescence (even under denaturing conditions), broad excitation and emission fluorescence spectra in the visible region of electromagnetic spectrum, and relatively low molecular weights make these molecules suitable for use as fluorescence labels of biomolecules and cells. We further designed fluorescent proteins both in vitro and in vivo (in Escherichia coli) based on the highly specific attachment of PEB chromophore to genetically expressed apo-subunits of R-PE. In one example, apo-alpha and apo-beta R-PE subunits were cloned from red algae Polisiphonia boldii (P. boldii), and expressed in E. coli. Although expressed apo-subunits formed inclusion

  1. Minority additive distributions in a ceramic metal-halide arc lamp using high-energy x-ray induced fluorescence

    NASA Astrophysics Data System (ADS)

    Curry, J. J.; Adler, H. G.; Shastri, S. D.; Lawler, J. E.

    2001-09-01

    X-ray induced fluorescence is used to measure the elemental densities of minority additives in a metal-halide arc contained inside a translucent ceramic envelope. A monochromatic x-ray beam from the Sector 1 Insertion Device beamline at the Advanced Photon Source is used to excite K-shell x-ray fluorescence in the constituents of a ceramic metal-halide arc lamp dosed with DyI3 and CsI. Fluorescence and scattered photons are collected by a cryogenic energy-resolving Ge detector. The high signal-to-noise spectra show strong fluorescence from Dy, Cs, and I, as well as elastic scattering from Hg. Radial distributions of the absolute elemental densities of Dy, Cs, and I are obtained.

  2. Minority additive distributions in a ceramic metal-halide arc lamp using high-energy x-ray induced fluorescence

    SciTech Connect

    Curry, J. J.; Adler, H. G.; Shastri, S. D.; Lawler, J. E.

    2001-09-24

    X-ray induced fluorescence is used to measure the elemental densities of minority additives in a metal-halide arc contained inside a translucent ceramic envelope. A monochromatic x-ray beam from the Sector 1 Insertion Device beamline at the Advanced Photon Source is used to excite K-shell x-ray fluorescence in the constituents of a ceramic metal-halide arc lamp dosed with DyI{sub 3} and CsI. Fluorescence and scattered photons are collected by a cryogenic energy-resolving Ge detector. The high signal-to-noise spectra show strong fluorescence from Dy, Cs, and I, as well as elastic scattering from Hg. Radial distributions of the absolute elemental densities of Dy, Cs, and I are obtained.

  3. Shock compression response of highly reactive Ni + Al multilayered thin foils

    NASA Astrophysics Data System (ADS)

    Kelly, Sean C.; Thadhani, Naresh N.

    2016-03-01

    The shock-compression response of Ni + Al multilayered thin foils is investigated using laser-accelerated thin-foil plate-impact experiments over the pressure range of 2 to 11 GPa. The foils contain alternating Ni and Al layers (parallel but not flat) of nominally 50 nm bilayer spacing. The goal is to determine the equation of state and shock-induced reactivity of these highly reactive fully dense thin-foil materials. The laser-accelerated thin-foil impact set-up involved combined use of photon-doppler-velocimetry to monitor the acceleration and impact velocity of an aluminum flyer, and VISAR interferometry was used to monitor the back free-surface velocity of the impacted Ni + Al multilayered target. The shock-compression response of the Ni + Al target foils was determined using experimentally measured parameters and impedance matching approach, with error bars identified considering systematic and experimental errors. Meso-scale CTH shock simulations were performed using real imported microstructures of the cross-sections of the multilayered Ni + Al foils to compute the Hugoniot response (assuming no reaction) for correlation with their experimentally determined equation of state. It was observed that at particle velocities below ˜150 m/s, the experimentally determined equation of state trend matches the CTH-predicted inert response and is consistent with the observed unreacted state of the recovered Ni + Al target foils from this velocity regime. At higher particle velocities, the experimentally determined equation of state deviates from the CTH-predicted inert response. A complete and self-sustained reaction is also seen in targets recovered from experiments performed at these higher particle velocities. The deviation in the measured equation of state, to higher shock speeds and expanded volumes, combined with the observation of complete reaction in the recovered multilayered foils, confirmed via microstructure characterization, is indicative of the occurrence

  4. Photo- and biophysical studies of lectin-conjugated fluorescent nanoparticles: reduced sensitivity in high density assays.

    PubMed

    Wang, Yaqi; Gildersleeve, Jeffrey C; Basu, Amit; Zimmt, Matthew B

    2010-11-18

    Lectin-conjugated, fluorescent silica nanoparticles (fNP) have been developed for carbohydrate-based histopathology evaluations of epithelial tissue biopsies. The fNP platform was selected for its enhanced emissive brightness compared to direct dye labeling. Carbohydrate microarray studies were performed to compare the carbohydrate selectivity of the mannose-recognizing lectin Concanavalin A (ConA) before and after conjugation to fluorescent silica nanoparticles (ConA-fNP). These studies revealed surprisingly low emission intensities upon staining with ConA-fNP compared to those with biotin-ConA/Cy3-streptavidin staining. A series of photophysical and biophysical characterizations of the fNP and ConA-fNP conjugates were performed to probe the low sensitivity from fNP in the microarray assays. Up to 1200 fluorescein (FL) and 80 tetramethylrhodamine (TR) dye molecules were incorporated into 46 nm diameter fNP, yielding emissive brightness values 400 and 35 times larger than the individual dye molecules, respectively. ConA lectin conjugated to carboxylic acid surface-modified nanoparticles covers 15-30% of the fNP surface. The CD spectra and mannose substrate selectivity of ConA conjugated to the fNP differed slightly compared to that of soluble ConA. Although, the high emissive brightness of fNP enhances detection sensitivity for samples with low analyte densities, large fNP diameters limit fNP recruitment and binding to samples with high analyte densities. The high analyte density and nearly two-dimensional target format of carbohydrate microarrays make probe size a critical parameter. In this application, fNP labels afford minimal sensitivity advantage compared to direct dye labeling.

  5. Biogeochemical processing of nutrients in groundwater-fed stream during baseflow conditions - the value of fluorescence spectroscopy and automated high-frequency nutrient monitoring

    NASA Astrophysics Data System (ADS)

    Bieroza, Magdalena; Heathwaite, Louise

    2014-05-01

    Recent research in groundwater-dominated streams indicates that organic matter plays an important role in nutrient transformations at the surface-groundwater interface known as the hyporheic zone. Mixing of water and nutrient fluxes in the hyporheic zone controls in-stream nutrients availability, dynamics and export to downstream reaches. In particular, benthic sediments can form adsorptive sinks for organic matter and reactive nutrients (nitrogen and phosphorus) that sustain a variety of hyporheic processes e.g. denitrification, microbial uptake. Thus, hyporheic metabolism can have an important effect on both quantity (concentration) and quality (labile vs. refractory character) of organic matter. Here high-frequency nutrient monitoring combined with spectroscopic analysis was used to provide insights into biogeochemical processing of a small, agricultural stream in the NE England subject to diffuse nutrient pollution. Biogeochemical data were collected hourly for a week at baseflow conditions when in-stream-hyporheic nutrient dynamics have the greatest impact on stream health. In-stream nutrients (total phosphorus, reactive phosphorus, nitrate nitrogen) and water quality parameters (turbidity, specific conductivity, pH, temperature, dissolved oxygen, redox potential) were measured in situ hourly by an automated bank-side laboratory. Concurrent hourly autosamples were retrieved daily and analysed for nutrients and fine sediments including spectroscopic analyses of dissolved organic matter - excitation-emission matrix (EEM) fluorescence spectroscopy and ultraviolet-visible (UV-Vis) absorbance spectroscopy. Our results show that organic matter can potentially be utilised as a natural, environmental tracer of the biogeochemical processes occurring at the surface-groundwater interface in streams. High-frequency spectroscopic characterisation of in-stream organic matter can provide useful quantitative and qualitative information on fluxes of reactive nutrients in

  6. High-Resolution Ultrasound-Switchable Fluorescence Imaging in Centimeter-Deep Tissue Phantoms with High Signal-To-Noise Ratio and High Sensitivity via Novel Contrast Agents

    PubMed Central

    Cheng, Bingbing; Bandi, Venugopal; Wei, Ming-Yuan; Pei, Yanbo; D’Souza, Francis; Nguyen, Kytai T.; Hong, Yi; Yuan, Baohong

    2016-01-01

    For many years, investigators have sought after high-resolution fluorescence imaging in centimeter-deep tissue because many interesting in vivo phenomena—such as the presence of immune system cells, tumor angiogenesis, and metastasis—may be located deep in tissue. Previously, we developed a new imaging technique to achieve high spatial resolution in sub-centimeter deep tissue phantoms named continuous-wave ultrasound-switchable fluorescence (CW-USF). The principle is to use a focused ultrasound wave to externally and locally switch on and off the fluorophore emission from a small volume (close to ultrasound focal volume). By making improvements in three aspects of this technique: excellent near-infrared USF contrast agents, a sensitive frequency-domain USF imaging system, and an effective signal processing algorithm, for the first time this study has achieved high spatial resolution (~ 900 μm) in 3-centimeter-deep tissue phantoms with high signal-to-noise ratio (SNR) and high sensitivity (3.4 picomoles of fluorophore in a volume of 68 nanoliters can be detected). We have achieved these results in both tissue-mimic phantoms and porcine muscle tissues. We have also demonstrated multi-color USF to image and distinguish two fluorophores with different wavelengths, which might be very useful for simultaneously imaging of multiple targets and observing their interactions in the future. This work has opened the door for future studies of high-resolution centimeter-deep tissue fluorescence imaging. PMID:27829050

  7. [Plasma concentration of C-reactive protein in patients with high estrogen levels].

    PubMed

    Ricoux, R; Pontet, M; Tresca, J P; Engler, R

    1994-01-01

    The monitoring of inflammatory activity in patients with a high level of estrogen is controversial because the significance of a raised estradiol level on C-reactive protein (CRP) concentrations is a debated question. This prompted us to assay CRP by a sensitive Elisa in a sample of 30 patients with ovarian stimulation for in vitro fertilization, thus with high levels of estradiol. For 15 of these women, six to nine plasma samples were analyzed allowing a kinetic study of plasma levels of CRP, estradiol and sex steroid-binding plasma protein (SBP). No significant correlation was found between the concentrations of estradiol and CRP for the 30 patients. In the kinetic study, as mean estradiol levels rose exponentially from 50 to 1400 ng/l between day 5 and 14, the CRP level tended to vary markedly from one patient to another and sometimes from day to day, but there was never any relation with estradiol level. Furthermore, CRP did not significantly modify the slope of the regression line between estradiol concentration and the day of the menstrual cycle. In contrast, the effect of estradiol on SBP was clear, which supports the absence of estradiol effect on CRP level.

  8. Reactively-sputtered zinc semiconductor films of high conductivity for heterojunction devices

    NASA Technical Reports Server (NTRS)

    Stirn, Richard J. (Inventor)

    1986-01-01

    A high conductivity, n-doped semiconductor film is produced from zinc, or Zn and Cd, and group VI elements selected from Se, S and Te in a reactive magnetron sputtering system having a chamber with one or two targets, a substrate holder, means for heating the substrate holder, and an electric field for ionizing gases in the chamber. Zinc or a compound of Zn and Cd is placed in the position of one of the two targets and doping material in the position of the other of the two targets. Zn and Cd may be placed in separate targets while a dopant is placed in the third target. Another possibility is to place an alloy of Zn and dopant, or Zn, Cd and dopant in one target, thus using only one target. A flow of the inert gas is ionized and directed toward said targets, while a flow of a reactant gas consisting of hydrides of the group VI elements is directed toward a substrate on the holder. The targets are biased to attract negatively ionized inert gas. The desired stochiometry for high conductivity is achieved by controlling the temperature of the substrate, and partial pressures of the gases, and the target power and total pressure of the gases in the chamber.

  9. Combined AFM nano-machining and reactive ion etching to fabricate high aspect ratio structures.

    PubMed

    Peng, Ping; Shi, Tielin; Liao, Guanglan; Tang, Zirong

    2010-11-01

    In this paper, a new combined method of sub-micron high aspect ratio structure fabrication is developed which can be used for production of nano imprint template. The process includes atomic force microscope (AFM) scratch nano-machining and reactive ion etching (RIE) fabrication. First, 40 nm aluminum film was deposited on the silicon substrate by magnetron sputtering, and then sub-micron grooves were fabricated on the aluminum film by nano scratch using AFM diamond tip. As aluminum film is a good mask for etching silicon, high aspect ratio structures were finally fabricated by RIE process. The fabricated structures were studied by SEM, which shows that the grooves are about 400 nm in width and 5 microm in depth. To obtain sub-micron scale groove structures on the aluminum film, experiments of nanomachining on aluminum films under various machining conditions were conducted. The depths of the grooves fabricated using different scratch loads were also studied by the AFM. The result shows that the material properties of the film/substrate are elastic-plastic following nearly a bilinear law with isotropic strain hardening. Combined AFM nanomachining and RIE process provides a relative lower cost nano fabrication technique than traditional e-beam lithography, and it has a good prospect in nano imprint template fabrication.

  10. Pebble Fuel Handling and Reactivity Control for Salt-Cooled High Temperature Reactors

    SciTech Connect

    Peterson, Per; Greenspan, Ehud

    2015-02-09

    This report documents the work completed on the X-PREX facility under NEUP Project 11- 3172. This project seeks to demonstrate the viability of pebble fuel handling and reactivity control for fluoride salt-cooled high-temperature reactors (FHRs). The research results also improve the understanding of pebble motion in helium-cooled reactors, as well as the general, fundamental understanding of low-velocity granular flows. Successful use of pebble fuels in with salt coolants would bring major benefits for high-temperature reactor technology. Pebble fuels enable on-line refueling and operation with low excess reactivity, and thus simpler reactivity control and improved fuel utilization. If fixed fuel designs are used, the power density of salt- cooled reactors is limited to 10 MW/m3 to obtain adequate duration between refueling, but pebble fuels allow power densities in the range of 20 to 30 MW/m3. This can be compared to the typical modular helium reactor power density of 5 MW/m3. Pebble fuels also permit radial zoning in annular cores and use of thorium or graphite pebble blankets to reduce neutron fluences to outer radial reflectors and increase total power production. Combined with high power conversion efficiency, compact low-pressure primary and containment systems, and unique safety characteristics including very large thermal margins (>500°C) to fuel damage during transients and accidents, salt-cooled pebble fuel cores offer the potential to meet the major goals of the Advanced Reactor Concepts Development program to provide electricity at lower cost than light water reactors with improved safety and system performance.This report presents the facility description, experimental results, and supporting simulation methods of the new X-Ray Pebble Recirculation Experiment (X-PREX), which is now operational and being used to collect data on the behavior of slow dense granular flows relevant to pebble bed reactor core designs. The X

  11. Application of LC-high-resolution MS with 'intelligent' data mining tools for screening reactive drug metabolites.

    PubMed

    Ma, Shuguang; Chowdhury, Swapan K

    2012-03-01

    Biotransformation of chemically stable compounds to reactive metabolites that can bind covalently to macromolecules (such as proteins and DNA) is considered an undesirable property of drug candidates. Due to the possible link, which has not yet been conclusively demonstrated, between reactive metabolites and adverse drug reactions, screening for metabolic activation of lead compounds through in vitro chemical trapping experiments has become an integral part of the drug discovery process in many laboratories. In this review, we provide an overview of the recent advances in the application of high-resolution MS. These advances facilitated the development of accurate-mass-based data mining tools for high-throughput screening of reactive drug metabolites in drug discovery.

  12. Preparation of Reactive Oligo(p-Phenylene Vinylene) Materials for Spatial Profiling of the Chemical Reactivity of Intracellular Compartments.

    PubMed

    Nie, Chenyao; Li, Shengliang; Wang, Bing; Liu, Libing; Hu, Rong; Chen, Hui; Lv, Fengting; Dai, Zhihui; Wang, Shu

    2016-05-01

    An oligo(p-phenylene vinylene) derivative (OPV-pfp) functionalized with pentafluorophenol active ester is designed and synthesized. The high reactivity of OPV-pfp with biological small molecules or macromolecules containing amino groups under physiological conditions leads to spectral changes of OPV-pfp; thus, spatial reactivity discrimination for different subcellular structures inside cells is realized by triggering and imaging the fluorescence signal change of the OPV-pfp.

  13. Identification of the High-Lying Pi Component of NiF by Laser-Induced Fluorescence.

    PubMed

    Jin, Jin; Chen, Yang; Yang, Xueliang; Ran, Qin; Chen, Congxiang

    2001-07-01

    The laser-induced fluorescence excitation spectrum of jet-cooled NiF has been studied in the range 435-570 nm. Eight electronic transitions, involving four high-lying Pi components and two lower states, the ground state X(2)Pi(3/2), and the low-lying state [0.25](2)Sigma, respectively, have been recorded. Two new Pi components are identified for the first time and their rotational constants are determined. The [20.4]Pi(3/2) component is assigned as the v'=1 level of the previously known [19.7](2)Pi(3/2) state. The [20.3]Pi(3/2) component may be linked to the component of an unreported quartet state. The previously reported [20.0](2)Pi(1/2) component is reassigned as a subcomponent of (2)Delta. Copyright 2001 Academic Press.

  14. High-speed atomic force microscope combined with single-molecule fluorescence microscope

    NASA Astrophysics Data System (ADS)

    Fukuda, Shingo; Uchihashi, Takayuki; Iino, Ryota; Okazaki, Yasutaka; Yoshida, Masato; Igarashi, Kiyohiko; Ando, Toshio

    2013-07-01

    High-speed atomic force microscopy (HS-AFM) and total internal reflection fluorescence microscopy (TIRFM) have mutually complementary capabilities. Here, we report techniques to combine these microscopy systems so that both microscopy capabilities can be simultaneously used in the full extent. To combine the two systems, we have developed a tip-scan type HS-AFM instrument equipped with a device by which the laser beam from the optical lever detector can track the cantilever motion in the X- and Y-directions. This stand-alone HS-AFM system is mounted on an inverted optical microscope stage with a wide-area scanner. The capability of this combined system is demonstrated by simultaneous HS-AFM/TIRFM imaging of chitinase A moving on a chitin crystalline fiber and myosin V walking on an actin filament.

  15. Novel Phenotypic Fluorescent Three-Dimensional Platforms for High-throughput Drug Screening and Personalized Chemotherapy.

    PubMed

    Fang, Changge; Avis, Ingalill; Salomon, David; Cuttitta, Frank

    2013-01-01

    We have developed novel phenotypic fluorescent three-dimensional co-culture platforms that efficiently and economically screen anti-angiogenic/anti-metastatic drugs on a high-throughput scale. Individual cell populations can be identified and isolated for protein/gene expression profiling studies and cellular movement/interactions can be tracked by time-lapse cinematography. More importantly, these platforms closely parallel the in vivo angiogenic and metastatic outcomes of a given tumor xenograft in the nude mouse model but, unlike in vivo models, our co-culture platforms produce comparable results in five to nine days. Potentially, by incorporating cancer patient biopsies, the co-culture platforms should greatly improve the effectiveness and efficiency of personalized chemotherapy.

  16. [Analysis of amines in water samples by high performance liquid chromatography-laser induced fluorescence detection].

    PubMed

    Liu, Fan; Gao, Fangyuan; Tang, Tao; Sun, Yuanshe; Li, Tong; Zhang, Weibing

    2013-11-01

    A sensitive high performance liquid chromatography (HPLC)-laser induced fluorescence detection (LIFD) method was developed for the determination of amines. The derivatization and separation conditions were investigated. Under the optimized conditions, spermidine, putrescine and histamine were analyzed. The limits of detection (LODs) of the three biogenic amines (S/N = 3) were as low as 10(-10) mol/L. This method showed excellent stability. The RSDs of retention times and peak areas of the three biogenic amines were lower than 0.3% and 3%, respectively. This method was applied in biogenic amine analysis in water samples, and the average recoveries were in the range of 94.99%-104.7%. Furthermore, the amines in seven tea samples were analyzed by this method, and satisfactory results were achieved. The developed assay is of excellent sensitivity and good reproducibility, which can be used in the analysis of the amines in water samples.

  17. High-resolution fluorescence excitation spectra of jet-cooled benzyl and p-methylbenzyl radicals

    NASA Astrophysics Data System (ADS)

    Lin, Tai-Yuan David; Tan, Xue-Qing; Cerny, Timothy M.; Williamson, James M.; Cullin, David W.; Miller, Terry A.

    1992-11-01

    High-resolution, rotationally resolved, laser-induced, fluorescence excitation spectra of the A 1 and 6a 10 bands of benzyl and the 0 00 band of p-methylbenzyl radicals were obtained in supersonic expansions. All three spectra were assigned and fit, using the rigid rotor Hamiltonian as well as methyl group internal rotation theory. The results of the rotational analysis provide good rotation constants for benzyl and p-methylbenzyl and establish unambiguously that the symmetry of the excited electronic state in this transition of p-methylbenzyl is 2A 2 (in C 2v). The heights of torsional barriers that hinder the internal rotation of the methyl group in p-methylbenzyl also are determined. The torsional results are compared to those obtained previously for this radical in a vibrational analysis and to other open shell radicals.

  18. High spectral resolution observations of fluorescent molecular hydrogen in molecular clouds

    NASA Technical Reports Server (NTRS)

    Burton, Michael G.; Geballe, T. R.; Brand, P. W. J. L.; Moorhouse, A.

    1990-01-01

    The 1-0 S(1) line of molecular hydrogen has been observed at high spectral resolution in several sources where the emission was suspected of being fluorescent. In NGC 2023, the Orion Bar, and Parsamyan 18, the S(1) line is unresolved, and the line center close to the rest velocity of the ambient molecular cloud. Such behavior is expected for UV-excited line emission. The H2 line widths in molecular clouds thus can serve as diagnostic for shocked and UV-excitation mechanisms. If the lines are broader than several km/s or velocity shifts are observed across a source it is likely that shocks are responsible for the excitation of the gas.

  19. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    SciTech Connect

    Zhang, Lei Chen, Haibin E-mail: mejswu@ust.hk; Wu, Jingshen E-mail: mejswu@ust.hk; Bi, Xianghong

    2014-05-15

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence.

  20. High Repetition Rate, LINAC-Based Nuclear Resonance Fluorescence FY 2008 Final Report

    SciTech Connect

    Scott M Watson; Mathew T Kinlaw; James L Jones; Alan W. Hunt; Glen A. Warren

    2008-12-01

    This summarizes the first year of a multi-laboratory/university, multi-year effort focusing on high repetition rate, pulsed LINAC-based nuclear resonance fluorescence (NRF) measurements. Specifically, this FY2008 effort centered on experimentally assessing NRF measurements using pulsed linear electron accelerators, operated at various repetition rates, and identifying specific detection requirements to optimize such measurements. Traditionally, interest in NRF as a detection technology, which continues to receive funding from DHS and DOE/NA-22, has been driven by continuous-wave (CW), Van de Graff-based bremsstrahlung sources. However, in addition to the relatively sparse present-day use of Van de Graff sources, only limited NRF data from special nuclear materials has been presented; there is even less data available regarding shielding effects and photon source optimization for NRF measurements on selected nuclear materials.

  1. High-Throughput Fluorescence-Based Isolation of Live C. elegans Larvae

    PubMed Central

    Fernandez, Anita G.; Bargmann, Bastiaan O. R.; Mis, Emily K.; Edgley, Mark. L.; Birnbaum, Kenneth D.; Piano, Fabio

    2017-01-01

    For the nematode Caenorhabditis elegans, automated selection of animals of specific genotypes from a mixed pool has become essential for genetic interaction or chemical screens. To date, such selection has been accomplished using specialized instruments. However, access to such dedicated equipment is not common. Here we describe live animal fluorescence-activated cell sorting (laFACS), a protocol for automatic selection of live L1 animals using a standard FACS. We show that a FACS can be used for the precise identification of GFP-expressing and non-GFP-expressing sub-populations and can accomplish high-speed sorting of live animals. We have routinely collected 100,000 or more homozygotes from a mixed starting population within two hours and with greater than ninety-nine percent purity. The sorted animals continue to develop normally, making this protocol ideally suited for the isolation of terminal mutants for use in genetic interaction or chemical genetic screens. PMID:22814389

  2. Comparison of fluorescent and high-pressure sodium lamps on growth of leaf lettuce

    NASA Technical Reports Server (NTRS)

    Koontz, H. V.; Prince, R. P.; Koontz, R. F.; Knott, W. M. (Principal Investigator)

    1987-01-01

    Radiation from high-pressure sodium (HPS) lamps provided more than a 50% increased yield (fresh and dry weight of tops) of loose-leaf lettuce cultivars Grand Rapids Forcing and RubyConn, compared to that obtained by radiation from cool-white fluorescent (CWF) lamps at equal photosynthetic photon flux; yet, input wattage was approximately 36% less. It was postulated that the considerable output of 700 to 850 nm radiation from the HPS lamp was a significant factor of the increased yield. Under HPS lamps, the leaves of both cultivars were slightly less green with very little red pigmentation ('RubyConn') and slightly elongated, compared to CWF, but plant productivity per unit electrical energy input was vastly superior with HPS.

  3. Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames

    NASA Technical Reports Server (NTRS)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.; Salmon, J. Thaddeus

    1987-01-01

    The effect of pressure on the laser-saturated fluorescence method for measuring OH concentration in high-pressure flames is studied using calculations for the burned-gas region of a stoichiometric H2-O2 flame at 2000 K. A numerical model of the excitation dynamics of OH is developed to explore the validity of the balanced cross-rate model at higher pressures. It is shown that depopulation of the laser-coupled levels is sensitive to collisions which depopulate v-double-prime (VDP) = 0 and to rate coefficients for rotational transfer in the ground state which are smaller than those in the excited state. In particular, it is shown that the depopulation of VDP = 0, and hence the laser-coupled levels, depends on the probability of electronic quenching to vibrational levels for which VDP is greater than 0 and vibrational relaxation to VDP = 0.

  4. High-Resolution Mesoscopic Fluorescence Molecular Tomography Based on Compressive Sensing

    PubMed Central

    Yang, Fugang; Ozturk, Mehmet S.; Zhao, Lingling; Cong, Wenxiang; Wang, Ge

    2017-01-01

    Mesoscopic fluorescence molecular tomography (MFMT) is new imaging modality aiming at 3-D imaging of molecular probes in a few millimeter thick biological samples with high-spatial resolution. In this paper, we develop a compressive sensing-based reconstruction method with l1-norm regularization for MFMT with the goal of improving spatial resolution and stability of the optical inverse problem. Three-dimensional numerical simulations of anatomically accurate microvasculature and real data obtained from phantom experiments are employed to evaluate the merits of the proposed method. Experimental results show that the proposed method can achieve 80 μm spatial resolution for a biological sample of 3 mm thickness and more accurate quantifications of concentrations and locations for the fluorophore distribution than those of the conventional methods. PMID:25137718

  5. New highly selective turn-on fluorescence receptor for the detection of copper (II)

    NASA Astrophysics Data System (ADS)

    Nan, Qian; Rong, Pu; Jiang, Yunbao; Yang, Rui

    2017-03-01

    Three new receptors (1a-c) bearing a p-dimethylaminobenzamide fluorophore have been synthesized and evaluated in terms of their fluoroionophoric properties towards various metal ions. Notably, receptors 1a and 1c exhibited dramatic fluorescent enhancement towards Cu2 + in acetonitrile. Subsequent investigations revealed that the highly selective behavior of these receptors towards Cu2 + could be attributed to the Cu2 +-mediated oxidative cyclization of these compounds to the corresponding 1,3,4-oxadiazoles. Solvent effects and quantum calculations indicated that 1a and 1c both possessed an intramolecular charge transfer channel, which could be obstructed by the oxidative cyclization of these receptors. Receptor 1a was successfully applied to the determination of the Cu2 + in drug sample with a low detection limit of 2.2 × 10- 8 mol L- 1.

  6. High-speed atomic force microscope combined with single-molecule fluorescence microscope.

    PubMed

    Fukuda, Shingo; Uchihashi, Takayuki; Iino, Ryota; Okazaki, Yasutaka; Yoshida, Masato; Igarashi, Kiyohiko; Ando, Toshio

    2013-07-01

    High-speed atomic force microscopy (HS-AFM) and total internal reflection fluorescence microscopy (TIRFM) have mutually complementary capabilities. Here, we report techniques to combine these microscopy systems so that both microscopy capabilities can be simultaneously used in the full extent. To combine the two systems, we have developed a tip-scan type HS-AFM instrument equipped with a device by which the laser beam from the optical lever detector can track the cantilever motion in the X- and Y-directions. This stand-alone HS-AFM system is mounted on an inverted optical microscope stage with a wide-area scanner. The capability of this combined system is demonstrated by simultaneous HS-AFM∕TIRFM imaging of chitinase A moving on a chitin crystalline fiber and myosin V walking on an actin filament.

  7. Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows

    NASA Technical Reports Server (NTRS)

    Bathel, Brett F.; Johansen, Criag; Inman, Jennifer A.; Jones, Stephen B.; Danehy, Paul M.

    2013-01-01

    This paper reviews five laser-induced fluorescence-based velocimetry techniques that have been used to study high-speed compressible flows at NASA Langley Research Center. The techniques discussed in this paper include nitric oxide (NO) molecular tagging velocimetry (MTV), nitrogen dioxide photodissociation (NO2-to-NO) MTV, and NO and atomic oxygen (O-atom) Doppler-shift-based velocimetry. Measurements of both single-component and two-component velocity have been performed using these techniques. This paper details the specific application and experiment for which each technique has been used, the facility in which the experiment was performed, the experimental setup, sample results, and a discussion of the lessons learned from each experiment.

  8. Incorporation of magnetite nanoparticle clusters in fluorescent silica nanoparticles for high-performance brain tumor delineation

    NASA Astrophysics Data System (ADS)

    Wan, Jiaqi; Meng, Xiangxi; Liu, Enzhong; Chen, Kezheng

    2010-06-01

    Bifunctional nanoprobes with both magnetic and optical contrast have been developed for ultra-sensitive brain tumor imaging at the cellular level. The nanoprobes were synthesized by simultaneously incorporating a magnetite nanoparticle cluster and fluorescence dyes into silica encapsulation by a sol-gel approach under ultrasonic treatment. The nanoprobes maintain superparamagnetic behavior at room temperature and possess enhanced transverse relaxivity and good photostability. As a glioma targeting ligand, chlorotoxin was covalently bonded to the surface of the nanoprobes. In vitro cellular uptake assays demonstrated that the nanoprobes were highly specific, taken up by human U251-MG glioma cells via receptor-mediated endocytosis. The labeled glioma cells were readily detectable by both MR imager and confocal laser scanning microscopy.

  9. Investigation of red blood cell antigens with highly fluorescent and stable semiconductor quantum dots.

    PubMed

    de Farias, Patrícia Maria Albuquerque; Santos, Beate Saegesser; de Menezes, Frederico Duarte; de Carvalho Ferreira, Ricardo; Barjas-Castro, Maria Lourdes; Castro, Vagner; Lima, Paulo Roberto Moura; Fontes, Adriana; Cesar, Carlos Lenz

    2005-01-01

    We report a new methodology for red blood cell antigen expression determination by a simple labeling procedure employing luminescent semiconductor quantum dots. Highly luminescent and stable core shell cadmium sulfide/cadmium hydroxide colloidal particles are obtained, with a predominant size of 9 nm. The core-shell quantum dots are functionalized with glutaraldehyde and conjugated to a monoclonal anti-A antibody to target antigen-A in red blood cell membranes. Erythrocyte samples of blood groups A+, A2+, and O+ are used for this purpose. Confocal microscopy images show that after 30 min of conjugation time, type A+ and A2+ erythrocytes present bright emission, whereas the O+ group cells show no emission. Fluorescence intensity maps show different antigen expressions for the distinct erythrocyte types. The results obtained strongly suggest that this simple labeling procedure may be employed as an efficient tool to investigate quantitatively the distribution and expression of antigens in red blood cell membranes.

  10. Comparison of fluorescent and high-pressure sodium lamps on growth of leaf lettuce.

    PubMed

    Koontz, H V; Prince, R P; Koontz, R F

    1987-06-01

    Radiation from high-pressure sodium (HPS) lamps provided more than a 50% increased yield (fresh and dry weight of tops) of loose-leaf lettuce cultivars Grand Rapids Forcing and RubyConn, compared to that obtained by radiation from cool-white fluorescent (CWF) lamps at equal photosynthetic photon flux; yet, input wattage was approximately 36% less. It was postulated that the considerable output of 700 to 850 nm radiation from the HPS lamp was a significant factor of the increased yield. Under HPS lamps, the leaves of both cultivars were slightly less green with very little red pigmentation ('RubyConn') and slightly elongated, compared to CWF, but plant productivity per unit electrical energy input was vastly superior with HPS.

  11. Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization.

    PubMed

    Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman

    2014-02-21

    Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are

  12. A highly reactive chalcogenide precursor for the synthesis of metal chalcogenide quantum dots

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Zhu, Dong-Liang; Zhu, Chun-Nan; Zhang, Zhi-Ling; Zhang, Guo-Jun; Pang, Dai-Wen

    2015-11-01

    Metal chalcogenide semiconductor nanocrystals (NCs) are ideal inorganic materials for solar cells and biomedical labeling. In consideration of the hazard and instability of alkylphosphines, the phosphine-free synthetic route has become one of the most important trends in synthesizing selenide QDs. Here we report a novel phase transfer strategy to prepare phosphine-free chalcogenide precursors. The anions in aqueous solution were transferred to toluene via electrostatic interactions between the anions and didodecyldimethylammonium bromide (DDAB). The obtained chalcogenide precursors show high reactivity with metal ions in the organic phase and could be applied to the low-temperature synthesis of various metal chalcogenide NCs based on a simple reaction between metal ions (e.g. Ag+, Pb2+, Cd2+) and chalcogenide anions (e.g. S2-) in toluene. In addition to chalcogenide anions, other anions such as BH4- ions and AuCl4- ions can also be transferred to the organic phase for synthesizing noble metal NCs (such as Ag and Au NCs).Metal chalcogenide semiconductor nanocrystals (NCs) are ideal inorganic materials for solar cells and biomedical labeling. In consideration of the hazard and instability of alkylphosphines, the phosphine-free synthetic route has become one of the most important trends in synthesizing selenide QDs. Here we report a novel phase transfer strategy to prepare phosphine-free chalcogenide precursors. The anions in aqueous solution were transferred to toluene via electrostatic interactions between the anions and didodecyldimethylammonium bromide (DDAB). The obtained chalcogenide precursors show high reactivity with metal ions in the organic phase and could be applied to the low-temperature synthesis of various metal chalcogenide NCs based on a simple reaction between metal ions (e.g. Ag+, Pb2+, Cd2+) and chalcogenide anions (e.g. S2-) in toluene. In addition to chalcogenide anions, other anions such as BH4- ions and AuCl4- ions can also be transferred to

  13. Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

    PubMed

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000-1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and

  14. Alpha reactivity to first names differs in subjects with high and low dream recall frequency

    PubMed Central

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000–1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high

  15. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    PubMed

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells.

  16. Single-cell analysis of dihydroartemisinin-induced apoptosis through reactive oxygen species-mediated caspase-8 activation and mitochondrial pathway in ASTC-a-1 cells using fluorescence imaging techniques

    NASA Astrophysics Data System (ADS)

    Lu, Ying-Ying; Chen, Tong-Sheng; Wang, Xiao-Ping; Li, Li

    2010-07-01

    Dihydroartemisinin (DHA), a front-line antimalarial herbal compound, has been shown to possess promising anticancer activity with low toxicity. We have previously reported that DHA induced caspase-3-dependent apoptosis in human lung adenocarcinoma cells. However, the cellular target and molecular mechanism of DHA-induced apoptosis is still poorly defined. We use confocal fluorescence microscopy imaging, fluorescence resonance energy transfer, and fluorescence recovery after photobleaching techniques to explore the roles of DHA-elicited reactive oxygen species (ROS) in the DHA-induced Bcl-2 family proteins activation, mitochondrial dysfunction, caspase cascade, and cell death. Cell Counting Kit-8 assay and flow cytometry analysis showed that DHA induced ROS-mediated apoptosis. Confocal imaging analysis in a single living cell and Western blot assay showed that DHA triggered ROS-dependent Bax translocation, mitochondrial membrane depolarization, alteration of mitochondrial morphology, cytochrome c release, caspase-9, caspase-8, and caspase-3 activation, indicating the coexistence of ROS-mediated mitochondrial and death receptor pathway. Collectively, our findings demonstrate for the first time that DHA induces cell apoptosis by triggering ROS-mediated caspase-8/Bid activation and the mitochondrial pathway, which provides some novel insights into the application of DHA as a potential anticancer drug and a new therapeutic strategy by targeting ROS signaling in lung adenocarcinoma therapy in the future.

  17. Alexandrite as a high-temperature pressure calibrant, and implications for the ruby-fluorescence scale

    NASA Technical Reports Server (NTRS)

    Jahren, A. H.; Kruger, M. B.; Jeanloz, Raymond

    1992-01-01

    The wavelength shifts of the R1 and R2 fluorescence lines of alexandrite (BeAl2O4:Cr(+3)) have been experimentally calibrated against the ruby-fluorescence scale as a function of both hydrostatic and nonhydrostatic pressures between 0 and 50 GPa, and simultaneously as a function of temperatures between 290 and 550 K. It is found that the pressure-temperature cross derivative of the fluorescence wavelength shifts are negligible for both ruby and alexandrite.

  18. A Dual Functional Electroactive and Fluorescent Probe for Coupled Measurements of Vesicular Exocytosis with High Spatial and Temporal Resolution.

    PubMed

    Liu, Xiaoqing; Savy, Alexandra; Maurin, Sylvie; Grimaud, Laurence; Darchen, François; Quinton, Damien; Labbé, Eric; Buriez, Olivier; Delacotte, Jérôme; Lemaître, Frédéric; Guille-Collignon, Manon

    2017-02-20

    In this work, Fluorescent False Neurotransmitter 102 (FFN102), a synthesized analogue of biogenic neurotransmitters, was demonstrated to show both pH-dependent fluorescence and electroactivity. To study secretory behaviors at the single-vesicle level, FFN102 was employed as a new fluorescent/electroactive dual probe in a coupled technique (amperometry and total internal reflection fluorescence microscopy (TIRFM)). We used N13 cells, a stable clone of BON cells, to specifically accumulate FFN102 into their secretory vesicles, and then optical and electrochemical measurements of vesicular exocytosis were experimentally achieved by using indium tin oxide (ITO) transparent electrodes. Upon stimulation, FFN102 started to diffuse out from the acidic intravesicular microenvironment to the neutral extracellular space, leading to fluorescent emissions and to the electrochemical oxidation signals that were simultaneously collected from the ITO electrode surface. The correlation of fluorescence and amperometric signals resulting from the FFN102 probe allows real-time monitoring of single exocytotic events with both high spatial and temporal resolution. This work opens new possibilities in the investigation of exocytotic mechanisms.

  19. Graphitic Carbon Nitride Nanosheets-Based Ratiometric Fluorescent Probe for Highly Sensitive Detection of H2O2 and Glucose.

    PubMed

    Liu, Jin-Wen; Luo, Ying; Wang, Yu-Min; Duan, Lu-Ying; Jiang, Jian-Hui; Yu, Ru-Qin

    2016-12-14

    Graphitic carbon nitride (g-C3N4) nanosheets, an emerging graphene-like carbon-based nanomaterial with high fluorescence and large specific surface areas, hold great potential for biosensor applications. Current g-C3N4 nanosheets based fluorescent biosensors majorly rely on single fluorescent intensity reading through fluorescence quenching interactions between the nanosheets and metal ions. Here we report for the first time the development of a novel g-C3N4 nanosheets-based ratiometric fluorescence sensing strategy for highly sensitive detection of H2O2 and glucose. With o-phenylenediamine (OPD) oxidized by H2O2 in the presence of horseradish peroxidase (HRP), the oxidization product can assemble on the g-C3N4 nanosheets through hydrogen bonding and π-π stacking, which effectively quenches the fluorescence of g-C3N4 while delivering a new emission peak. The ratiometric signal variations enable robust and sensitive detection of H2O2. On the basis of the glucose converting into H2O2 through the catalysis of glucose oxidase, the g-C3N4-based ratiometric fluorescence sensing platform is also exploited for glucose assay. The developed strategy is demonstrated to give a detection limit of 50 nM for H2O2 and 0.4 μM for glucose, at the same time, it has been successfully used for glucose levels detection in human serum. This strategy may provide a cost-efficient, robust, and high-throughput platform for detecting various species involving H2O2-generation reactions for biomedical applications.

  20. High-pressure reactively sputtered HfO2: Composition, morphology, and optical properties

    NASA Astrophysics Data System (ADS)

    Toledano-Luque, M.; San Andrés, E.; del Prado, A.; Mártil, I.; Lucía, M. L.; González-Díaz, G.; Martínez, F. L.; Bohne, W.; Röhrich, J.; Strub, E.

    2007-08-01

    Hafnium oxide films were deposited by high pressure reactive sputtering using different deposition pressures and times. The composition, morphology, and optical properties of the films, together with the sputtering process growth kinetics were investigated using heavy ion elastic recoil detection analysis, Fourier transform infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy, x-ray diffraction, and transmission electron microscopy. The films showed a monoclinic polycrystalline structure, with a grain size depending on the deposition pressure. All films were slightly oxygen rich with respect to stoichiometric HfO2 and presented a significant amount of hydrogen (up to 6at.%), which is attributed to the high affinity for moisture of the HfO2 films. The absorption coefficient was fitted to the Tauc law, obtaining a band gap value of 5.54eV. It was found that the growth rate of the HfO2 films depends on the deposition pressure (P ) as P-1.75. This dependence is explained by a diffusion model of the thermalized atoms in high-pressure sputtering. Additionally, the formation of an interfacial silicon oxide layer when the films were grown on silicon was observed, with a minimum thickness for deposition pressures around 1.2mbars. This interfacial layer was formed mainly during the initial stages of the deposition process, with only a slight increase in thickness afterwards. These results are explained by the oxidizing action of the oxygen plasma and the diffusion of oxygen radicals and hydroxyl groups through the polycrystalline HfO2 film. Finally, the dielectric properties of the HfO2/SiO2 stacks were studied by means of conductance and capacitance measurements on Al /HfO2/SiO2/Si devices as a function of gate voltage and ac frequency signal.

  1. High metal reactivity and environmental risks at a site contaminated by glass waste.

    PubMed

    Augustsson, A; Åström, M; Bergbäck, B; Elert, M; Höglund, L O; Kleja, D B

    2016-07-01

    This study addresses the reactivity and risks of metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, As and Sb) at a Swedish site with large glass waste deposits. Old glassworks sites typically have high total metal concentrations, but as the metals are mainly bound within the glass waste and considered relatively inert, environmental investigations at these kinds of sites are limited. In this study, soil and landfill samples were subjected to a sequential chemical extraction procedure. Data from batch leaching tests and groundwater upstream and downstream of the waste deposits were also interpreted. The sequential extraction revealed that metals in <2 mm soil/waste samples were largely associated with geochemically active fractions, indicating that metals are released from pristine glass and subsequently largely retained in the surrounding soil and/or on secondary mineral coatings on fine glass particles. From the approximately 12,000 m(3) of coarse glass waste at the site, almost 4000 kg of Pb is estimated to have been lost through corrosion, which, however, corresponds to only a small portion of the total amount of Pb in the waste. Metal sorption within the waste deposits or in underlying soil layers is supported by fairly low metal concentrations in groundwater. However, elevated concentrations in downstream groundwater and in leachates of batch leaching tests were observed for several metals, indicating on-going leaching. Taken together, the high metal concentrations in geochemically active forms and the high amounts of as yet uncorroded metal-rich glass, indicate considerable risks to human health and the environment.

  2. Three step deep reactive ion etch for high density trench etching

    NASA Astrophysics Data System (ADS)

    Lips, B.; Puers, R.

    2016-10-01

    A three step Deep Reactive Ion Etch (DRIE) process is developed to etch trenches of 10μm wide to a depth of 130μm into silicon with an etch rate of 2.5μm min-1. The aim of this process is to obtain sidewalls with an angle close to 90°. The process allows the etching of multiple trenches with high aspect ratios that are closely placed together. A three step approach is used as opposed to the more conventional two step approach in an attempt to improve the etching selectivity with respect to the masking material. By doing so, a simple AZ6632 positive photoresist could be used instead of the more commonly used metal masks which are harder to remove afterwards. In order to develop this process, four parameters, which are the bias power, processing pressure, step times and number of cycles, are evaluated an optimized on a PlasmaPro 300 Cobra DRIE tool from Oxford Plasma Technology.

  3. Anthropogenic emissions of highly reactive volatile organic compounds inferred from oversampling of OMI HCHO columns

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Jacob, D. J.; Mickley, L. J.; Marais, E. A.; Cohan, D. S.; Yoshida, Y.; Duncan, B. N.; Gonzalez Abad, G.; Chance, K.

    2014-12-01

    Satellite observations of formaldehyde (HCHO) columns provide top-down constraints on emissions of highly reactive volatile organic compounds (HRVOCs). This approach has been used previously to constrain emissions of isoprene from vegetation, but application to US anthropogenic emissions has been stymied by lack of a discernable HCHO signal. Here we show that oversampling of HCHO data from the Ozone Monitoring Instrument (OMI) for 2005-2008 enables quantitative detection of urban and industrial plumes in eastern Texas including Houston, Port Arthur, and Dallas/Fort Worth. By spatially integrating the individual urban/industrial HCHO plumes observed by OMI we can constrain the corresponding HCHO-weighted HRVOC emissions. Application to the Houston plume indicates a HCHO source of 260±110 kmol h-1 and implies a factor of 5.5±2.4 underestimate of anthropogenic HRVOC emissions in the US Environmental Protection Agency inventory. This approach allows us to monitor trends in HRVOC emissions over the US, in particular from the urban areas and oil/gas industry.

  4. Anthropogenic Emissions of Highly Reactive Volatile Organic Compounds (HRVOCs) Inferred from Oversampling of OMI HCHO Columns

    NASA Technical Reports Server (NTRS)

    Zhu, Lei; Jacob, Daniel; Mickley, Loretta; Marais, Eloise; Zhang, Aoxing; Cohan, Daniel; Yoshida, Yasuko; Duncan, Bryan; Abad, Gonzalo Gonzalez; Chance, Kelly; DeSmedt, Isabelle

    2014-01-01

    Satellite observations of formaldehyde (HCHO) columns provide top-down constraints on emissions of highly reactive volatile organic compounds (HRVOCs). This approach has been used previously to constrain emissions of isoprene from vegetation, but application to US anthropogenic emissions has been stymied by lack of a discernable HCHO signal. Here we show that oversampling of HCHO data from the Ozone Monitoring Instrument (OMI) for 2005 - 2008 enables quantitative detection of urban and industrial plumes in eastern Texas including Houston, Port Arthur, and Dallas-Fort Worth. By spatially integrating the individual urban-industrial HCHO plumes observed by OMI we can constrain the corresponding HCHO-weighted HRVOC emissions. Application to the Houston plume indicates a HCHO source of 260 plus or minus 110 kmol h-1 and implies a factor of 5.5 plus or minus 2.4 underestimate of anthropogenic HRVOC emissions in the US Environmental Protection Agency inventory. With this approach we are able to monitor the trend in HRVOC emissions over the US, in particular from the oil-gas industry, over the past decade.

  5. A Highly Reactive Imidazolium-Bridged Dinucleotide Intermediate in Nonenzymatic RNA Primer Extension.

    PubMed

    Walton, Travis; Szostak, Jack W

    2016-09-14

    Because of its importance for the origin of life, the nonenzymatic copying of RNA templates has been the subject of intense study for several decades. Previous characterizations of template-directed primer extension using 5'-phosphoryl-2-methylimidazole-activated nucleotides (2-MeImpNs) as substrates have assumed a classical in-line nucleophilic substitution mechanism, in which the 3'-hydroxyl of the primer attacks the phosphate of the incoming monomer, displacing the 2-methylimidazole leaving group. However, we have found that the initial rate of primer extension depends on the pH and concentration at which the activated monomer is maintained prior to the primer extension reaction. These and other results suggest an alternative mechanism, in which two monomers react with each other to form an imidazolium-bridged dinucleotide intermediate, which then binds to the template. Subsequent attack of the 3'-hydroxyl of the primer displaces an activated nucleotide as the leaving group and results in extension of the primer by one nucleotide. Analysis of monomer solutions by NMR indicates formation of the proposed imidazolium-bridged dinucleotide in the expected pH-dependent manner. We have used synthetic methods to prepare material that is enriched in this proposed intermediate and show that it is a highly reactive substrate for primer extension. The formation of an imidazolium-bridged dinucleotide intermediate provides a mechanistic interpretation of previously observed catalysis by an activated nucleotide located downstream from the site of primer extension.

  6. Oxidative Reactivities of 2-Furylquinolines: Ubiquitous Scaffolds in Common High-Throughput Screening Libraries

    PubMed Central

    Olson, Margaret E.; Abate-Pella, Daniel; Perkins, Angela L.; Li, Ming; Carpenter, Michael A.; Rathore, Anurag; Harris, Reuben S.; Harki, Daniel A.

    2015-01-01

    High-throughput screening (HTS) was employed to discover APOBEC3G inhibitors and multiple 2-furylquinolines (e.g., 1) were found. Dose-response assays with 1 from the HTS sample, as well as commercial material, yielded similar confirmatory results. Interestingly, freshly synthesized and DMSO-solubilized 1 was inactive. Repeated screening of the DMSO aliquot of synthesized 1 revealed increasing APOBEC3G inhibitory activity with age, suggesting 1 decomposes into an active inhibitor. Laboratory aging of 1 followed by analysis revealed that 1 undergoes oxidative decomposition in air, resulting from a [4+2] cycloaddition between the furan of 1 and 1O2. The resulting endoperoxide then undergoes additional transformations, highlighted by Baeyer-Villager rearrangements, to deliver lactam, carboxylic acid, and aldehyde products. The endoperoxide also undergoes hydrolytic opening followed by further transformations to a bis-enone. Eight structurally related analogues from HTS libraries were similarly reactive. This study constitutes a cautionary to validate 2-furylquinolines for structure and stability prior to chemical optimization campaigns. PMID:26358009

  7. Perspective: Is there a hysteresis during reactive High Power Impulse Magnetron Sputtering (R-HiPIMS)?

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Moens, F.; Depla, D.

    2017-02-01

    This paper discusses a few mechanisms that can assist to answer the title question. The initial approach is to use an established model for DC magnetron sputter deposition, i.e., RSD2013. Based on this model, the impact on the hysteresis behaviour of some typical HiPIMS conditions is investigated. From this first study, it becomes clear that the probability to observe hysteresis is much lower as compared to DC magnetron sputtering. The high current pulses cannot explain the hysteresis reduction. Total pressure and material choice make the abrupt changes less pronounced, but the implantation of ionized metal atoms that return to the target seems to be the major cause. To further substantiate these results, the analytical reactive sputtering model is coupled with a published global plasma model. The effect of metal ion implantation is confirmed. Another suggested mechanism, i.e., gas rarefaction, can be ruled out to explain the hysteresis reduction. But perhaps the major conclusion is that at present, there are too little experimental data available to make fully sound conclusions.

  8. Associations of High Sensitivity C-Reactive Protein Levels in Schizophrenia and Comparison Groups

    PubMed Central

    Joseph, Jamie; Depp, Colin; Martin, Averria Sirkin; Daly, Rebecca; Glorioso, Danielle K; Palmer, Barton W; Jeste, Dilip V

    2015-01-01

    Schizophrenia is characterized by physical (mainly metabolic and cardiovascular) comorbidity and shortened lifespan. High sensitivity C- reactive protein (hs-CRP), an inflammatory marker of hepatic origin linked to metabolic and cardiovascular diseases and mortality in the general population, has been reported to be elevated in people with schizophrenia. However, the relationship of hs-CRP to psychiatric and medical risk factors, after controlling for potentially confounding variables such as smoking, is not well established in schizophrenia. We assessed hs-CRP levels along with various demographic, psychiatric, and metabolic measures in 88 clinically stable outpatients with schizophrenia or schizoaffective disorder and 71 age epoch-matched comparison subjects with no history of a major psychiatric illness. hs-CRP levels were significantly higher in individuals with schizophrenia than in comparison subjects. Higher hs-CRP levels in schizophrenia group were associated with female gender, more severe negative symptoms, greater medical comorbidity, and worse metabolic risk factors including BMI, fasting glucose, and hemoglobin A1c levels. hs-CRP was not related to age, race, education, smoking status, antipsychotic dosage, or cognitive impairment. Longitudinal studies are needed to investigate the relationship between hs-CRP and long-term health outcomes including metabolic syndrome, cardiovascular disease, and mortality in schizophrenia. PMID:26341579

  9. Evidence for Different Reactive Hg Sources and Chemical Compounds at Adjacent Valley and High Elevation Locations.

    PubMed

    Sexauer Gustin, Mae; Pierce, Ashley M; Huang, Jiaoyan; Miller, Matthieu B; Holmes, Heather A; Loria-Salazar, S Marcela

    2016-11-15

    The spatial distribution of chemical compounds and concentration of reactive mercury (RM), defined as the sum of gaseous oxidized mercury (GOM) and <3 μm particulate bound mercury (PBM), are poorly characterized. The objective of this study was to understand the chemistry, concentration, and spatial and temporal distribution of GOM at adjacent locations (12 km apart) with a difference in elevation of ∼1000 m. Atmospheric GOM measurements were made with passive and active samplers using membranes, and at one location, a Tekran mercury measurement system was used. The chemistry of GOM varied across time and location. On the basis of data collected, chemistry at the low elevation site adjacent to a highway was primarily influenced by pollutants generated by mobile sources (GOM = nitrogen and sulfur-based compounds), and the high elevation site (GOM = halogen-based compounds) was affected by long-range transport in the free troposphere over the marine boundary layer into Nevada. Data collected at these two locations demonstrate that different GOM compounds exist depending on the oxidants present in the air. Measurements of GOM made by the KCl denuder in the Tekran instrument located at the low elevation site were lower than that measured using membranes by 1.7-13 times. Accurate measurements of atmospheric concentrations and chemistry of RM are necessary for proper assessment of environmental impacts, and field measurements are essential for atmospheric models, which in turn influence policy decisions.

  10. The Complementary Role of High Sensitivity C-Reactive Protein in the Diagnosis and Severity Assessment of Autism

    ERIC Educational Resources Information Center

    Khakzad, Mohammad Reza; Javanbakht, Maryam; Shayegan, Mohammad Reza; Kianoush, Sina; Omid, Fatemeh; Hojati, Maryam; Meshkat, Mojtaba

    2012-01-01

    C-reactive protein (CRP) is a beneficial diagnostic test for the evaluation of inflammatory response. Extremely low levels of CRP can be detected using high-sensitivity CRP (hs-CRP) test. A considerable body of evidence has demonstrated that inflammatory response has an important role in the pathophysiology of autism. In this study, we evaluated…

  11. Regulatory Behaviors and Stress Reactivity among Infants at High Risk for Fetal Alcohol Spectrum Disorders: An Exploratory Study

    ERIC Educational Resources Information Center

    Jirikowic, Tracy; Chen, Maida; Nash, Jennifer; Gendler, Beth; Olson, Heather Carmichael

    2016-01-01

    Introduction: This article examines regulatory behaviors and physiological stress reactivity among 6-15 month-old infants with moderate to heavy prenatal alcohol exposure (PAE), a group at very high risk for fetal alcohol spectrum disorders and self-regulation impairments, compared to low risk infants with no/low exposure. Participants: Eighteen…

  12. Soot Structure and Reactivity Analysis by Raman Microspectroscopy, Temperature-Programmed Oxidation, and High-Resolution Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Knauer, Markus; Schuster, Manfred E.; Su, Dangsheng; Schlögl, Robert; Niessner, Reinhard; Ivleva, Natalia P.

    2009-11-01

    Raman microspectroscopy (RM), temperature-programmed oxidation (TPO), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS) were combined to get comprehensive information on the relationship between structure and reactivity of soot in samples of spark discharge (GfG), heavy duty engine diesel (EURO VI and IV) soot, and graphite powder upon oxidation by oxygen at increasing temperatures. GfG soot and graphite powder represent the higher and lower reactivity limits. Raman microspectroscopic analysis was conducted by determination of spectral parameters using a five band fitting procedure (G, D1-D4) as well as by evaluation of the dispersive character of the D mode. The analysis of spectral parameters shows a higher degree of disorder and a higher amount of molecular carbon for untreated GfG soot samples than for samples of untreated EURO VI and EURO IV soot. The structural analysis based on the dispersive character of the D mode revealed substantial differences in ordering descending from graphite powder, EURO IV, VI to GfG soot. HRTEM images and EELS analysis of EURO IV and VI samples indicated a different morphology and a higher structural order as compared to GfG soot in full agreement with the Raman analysis. These findings are also confirmed by the reactivity of soot during oxidation (TPO), where GfG soot was found to be the most reactive and EURO IV and VI soot samples exhibited a moderate reactivity.

  13. Peptide reactivity assay using spectrophotometric method for high-throughput screening of skin sensitization potential of chemical haptens.

    PubMed

    Jeong, Yun Hyeok; An, Susun; Shin, Kyeho; Lee, Tae Ryong

    2013-02-01

    Haptens must react with cellular proteins to be recognized by antigen presenting cells. Therefore, monitoring reactivity of chemicals with peptide/protein has been considered an in vitro skin sensitization testing method. The reactivity of peptides with chemicals (peptide reactivity) has usually been monitored by chromatographic methods like HPLC or LC/MS, which are robust tools for monitoring common chemical reactions but are rather expensive and time consuming. Here, we examined the possibility of using spectrophotometric methods to monitor peptide reactivity. Two synthetic peptides, Ac-RWAACAA and Ac-RWAAKAA, were reacted with 48 chemicals (34 sensitizers and 14 non-sensitizers). Peptide reactivity was measured by monitoring unreacted peptides with UV-Vis spectrophotometer using 5,5'-dithiobis-2-nitrobenzoic acid as a detection reagent for the free thiol group of cysteine-containing peptide or fluorometer using fluorescamine™ as a detection reagent for the free amine group of lysine-containing peptide. Chemicals were categorized as sensitizers when they induced more than 10% depletion of cysteine-containing peptide or 20% depletion of lysine-containing peptide. The sensitivity, specificity, and accuracy of this method were 82.4%, 85.7%, and 83.3%, respectively. These results demonstrate that spectrophotometric methods can be easy, fast, and high-throughput screening tools for the prediction of the skin sensitization potential of chemical haptens.

  14. Highly Sensitive Detection of S-Nitrosylated Proteins by Capillary Gel Electrophoresis with Laser Induced Fluorescence

    PubMed Central

    Wang, Siyang; Circu, Magdalena L.; Zhou, Hu; Figeys, Daniel; Aw, Tak Y.; Feng, June

    2011-01-01

    S-nitrosylated proteins are biomarkers of oxidative damage in aging and Alzheimer’s disease (AD). Here, we report a new method for detecting and quantifying nitrosylated proteins by capillary gel electrophoresis with laser induced fluorescence detection (CGE-LIF). Dylight 488 maleimide was used to specifically label thiol group (SH) after switching the S-nitrosothiol(S-NO) to SH in cysteine using the “fluorescence switch” assay. In vitro nitrosylation model-BSA subjected to S-nitrosoglutathione(GSNO) optimized the labeling reactions and characterized the response of the LIF detector. The method proves to be highly sensitive, detecting 1.3 picomolar (pM)concentration of nitrosothiols in nanograms of proteins, which is the lowest limit of detection of nitrosothiols reported to date. We further demonstrated the direct application of this method in monitoring protein nitrosylation damage in MQ mediated human colon adenocarcinoma cells. The nitrosothiol amounts in MQ treated and untreated cells are 14.8±0.2 and 10.4±0.5 pmol/mg of proteins, respectively. We also depicted nitrosylated protein electrophoretic profiles of brain cerebrum of 5-month-old AD transgenic (Tg) mice model. In Tg mice brain, 15.5±0.4 pmol of nitrosothiols/mg of proteins was quantified while wild type contained 11.7±0.3 pmol/mg proteins. The methodology is validated to quantify low levels of S-nitrosylated protein in complex protein mixtures from both physiological and pathological conditions. PMID:21820121

  15. High fluorescent and stable semiconductor quantum dots for red blood cells labeling

    NASA Astrophysics Data System (ADS)

    de Farias, Patricia M. A.; Santos, Beate S.; de Menezes, Frederico D.; Ferreira, Ricardo; Fontes, Adriana; Cesar, Carlos L.; Barjas Castro, Maria L.; Castro, Vagner; Lima, Paulo R. M.

    2005-04-01

    We present a simple and efficient method for marking living human red blood cells using CdS (Cadmium Sulfide) quantum dots (QDs). The nanocrystals were obtained via colloidal synthesis in aqueous medium with final pH=7 using sodium polyphosphate as the stabilizing agent. The methodology implementation is simple, do not requires additional capping layers nor narrow size QDs distribution. The synthesized nanoparticles were conjugated to monoclonal A anti-body. The resulting conjugates QDs/anti-A were incubated with human erythrocytes of blood groups A and O for 30 min at 37°C. The living cells in contact with the quantum dots maintained their properties for several days showing the low level of citotoxicity of the quantum dots. The conjugation of CdS QDs/anti-A show simultaneous red and green fluorescence when excited with 543 and 488 nm respectively. The efficiency of the conjugation QDs/anti-body to the erythrocytes, for each system, was monitored by confocal microscopy. The comparative analysis of the micrographs was done with the luminescence intensity maps of the samples obtained under constant capture conditions, such as, pinhole, filters, beam splitters and photomultiplier gain. The conjugates QDs/anti-A intensely marked group A erythrocytes and did not show any luminescence for group O erythrocytes, showing the sensitivity of the labeling procedure. In conclusion, we show the viability of the use of high luminescent and stable quantum dots as fluorescent labels for human erythrocytes with a methodology of simple implementation and the possibility to use them to distinguish different blood groups.

  16. High frequency application of nanosecond pulsed electric fields alters cellular membrane disruption and fluorescent dye uptake

    NASA Astrophysics Data System (ADS)

    Steelman, Zachary A.; Tolstykh, Gleb P.; Beier, Hope T.; Ibey, Bennett L.

    2016-03-01

    Cells exposed to nanosecond-pulsed electric fields (nsPEF) exhibit a wide variety of nonspecific effects, including blebbing, swelling, intracellular calcium bursts, apoptotic and necrotic cell death, formation of nanopores, and depletion of phosphatidylinositol 4,5-biphosphate (PIP2) to induce activation of the inositol trisphosphate/diacylglycerol pathway. While several studies have taken place in which multiple pulses were delivered to cells, the effect of pulse repetition rate (PRR) is not well understood. To better understand the effects of PRR, a laser scanning confocal microscope was used to observe CHO-K1 cells exposed to ten 600ns, 200V pulses at varying repetition rates (5Hz up to 500KHz) in the presence of either FM 1-43, YO-PRO-1, or Propidium Iodide (PI) fluorescent dyes, probes frequently used to indicate nanoporation or permeabilization of the plasma membrane. Dye uptake was monitored for 30 seconds after pulse application at a rate of 1 image/second. In addition, a single long pulse of equivalent energy (200V, 6 μs duration) was applied to test the hypothesis that very fast PRR will approximate the biological effects of a single long pulse of equal energy. Upon examination of the data, we found strong variation in the relationship between PRR and uptake in each of the three dyes. In particular, PI uptake showed little frequency dependence, FM 1-43 showed a strong inverse relationship between frequency and internal cell fluorescence, and YO-PRO-1 exhibited a "threshold" point of around 50 KHz, after which the inverse trend observed in FM 1-43 was seen to reverse itself. Further, a very high PRR of 500 KHz only approximated the biological effects of a single 6 μs pulse in cells stained with YO-PRO-1, suggesting that uptake of different dyes may proceed by different physical mechanisms.

  17. A highly selective fluorescent sensor for Fe3+ based on covalently immobilized derivative of naphthalimide

    NASA Astrophysics Data System (ADS)

    Xu, Jun-Hong; Hou, Yi-Min; Ma, Qiu-Juan; Wu, Xue-Fen; Wei, Xiao-Jie

    2013-08-01

    In this paper, the fabrication and analytical characteristics of fluorescence-based ferric ion-sensing glass slides were described. To fabricate the sensor, a naphthalimide derivative (compound 1) with a terminal double bond was synthesized and copolymerized with 2-hydroxyethyl methacrylate (HEMA) on the activated surface of glass slides by UV irradiation. Upon the addition of Fe3+ in 0.05 mol/L Tris/HCl (pH 6.02) at 25 °C, the fluorescence intensity of the resulting optical sensor decrease, which has been utilized as the basis for the selective detection of Fe3+. The sensor can be applied to the quantification of Fe3+ with a linear range covering form 1.0 × 10-5 to 1.0 × 10-3 M and a detection limit of 4.5 × 10-6 M. The experiment results show that the response behavior of the sensor to Fe3+ is pH-independent in medium condition (pH 5.00-8.00) and exhibits high selectivity for Fe3+ over a large number of cations such as alkali, alkaline earth and transitional metal ions. Moreover, satisfactory reproducibility, reversibility and a rapid response were realized. The sensing membrane was found to have a lifetime at least 2 months. The accuracy and the precision of the method were evaluated by the analysis of the standard reference material, iron in water (1.0 mol/L HNO3). The developed sensor is applied for the determination of iron in pharmaceutical preparation samples with satisfactory results.

  18. A New Domain of Reactivity for High-Valent Dinuclear [M(μ-O)2 M'] Complexes in Oxidation Reactions.

    PubMed

    Engelmann, Xenia; Yao, Shenglai; Farquhar, Erik R; Szilvási, Tibor; Kuhlmann, Uwe; Hildebrandt, Peter; Driess, Matthias; Ray, Kallol

    2017-01-02

    The strikingly different reactivity of a series of homo- and heterodinuclear [(M(III) )(μ-O)2 (M(III) )'](2+) (M=Ni; M'=Fe, Co, Ni and M=M'=Co) complexes with β-diketiminate ligands in electrophilic and nucleophilic oxidation reactions is reported, and can be correlated to the spectroscopic features of the [(M(III) )(μ-O)2 (M(III) )'](2+) core. In particular, the unprecedented nucleophilic reactivity of the symmetric [Ni(III) (μ-O)2 Ni(III) ](2+) complex and the decay of the asymmetric [Ni(III) (μ-O)2 Co(III) ](2+) core through aromatic hydroxylation reactions represent a new domain for high-valent bis(μ-oxido)dimetal reactivity.

  19. Reactive trace element enrichment in a highly modified, tidally inundated acid sulfate soil wetland: East Trinity, Australia.

    PubMed

    Keene, Annabelle F; Johnston, Scott G; Bush, Richard T; Burton, Edward D; Sullivan, Leigh A

    2010-04-01

    This study examines the abundance of trace elements in surface sediments of a former acid sulfate soil (ASS) wetland subjected to marine tidal inundation. Sediment properties of this highly modified study site are compared with those of an adjacent unmodified, intertidal mangrove forest. Whilst some trace elements (Al, Cd, Mn, Ni and Zn) were clearly depleted due to mobilisation and leaching in the previous oxic-acidic phase, other trace elements (As and Cr) displayed significant enrichment in the tidally inundated ASS. Many trace elements were strongly associated with the reactive Fe and acid volatile sulfide (AVS) fractions, suggesting that trace elements may be adsorbed to abundant reactive Fe phases or sequestered as sulfide minerals. These findings provide an important understanding of the fate and mobility of reactive iron, AVS and trace elements during tidal remediation of a formerly acidified Great Barrier Reef (GBR) catchment.

  20. Reactive sintering and reactive hot

    NASA Astrophysics Data System (ADS)

    Murray, J. C.; German, R. M.

    1992-09-01

    NbAl3 has been synthesized from elemental powders by reactive sintering (RS) and reactive hot isostatic pressing (RHIP). Both processes involve a self-propagating exothermic reaction between the constituent powders to form an intermetallic compound. The RHIP approach uses simultaneous external pressurization to make a higher density product. This study focused on developing a method to use reactive synthesis to form high-density NbAl3 compacts. High RS and RHIP densities were possible with the appropriate raw materials and processing parameters. These include powder purity, particle sizes, degassing, heating rate, furnace temperature, and compaction pressures. Near full density was attained with RHIP, and up to 95 pct density was attained with RS.

  1. Visual and fluorescent detection of tyrosinase activity by using a dual-emission ratiometric fluorescence probe.

    PubMed

    Yan, Xu; Li, Hongxia; Zheng, Weishi; Su, Xingguang

    2015-09-01

    In this work, we designed a dual-emission ratiometric fluorescence probe by hybridizing two differently colored quantum dots (QDs), which possess a built-in correction that eliminates the environmental effects and increases sensor accuracy. Red emissive QDs were embedded in the silica nanoparticle as reference while the green emissive QDs were covalently linked to the silica nanoparticle surface to form ratiometric fluorescence probes (RF-QDs). Dopamine (DA) was then conjugated to the surface of RF-QDs via covalent bonding. The ratiometric fluorescence probe functionalized with dopamine (DA) was highly reactive toward tyrosinase (TYR), which can catalyze the oxidization of DA to dopamine quinine and therefore quenched the fluorescence of the green QDs on the surface of ratiometric fluorescence probe. With the addition of different amounts of TYR, the ratiometric fluorescence intensity of the probe continually varied, leading to color changes from yellow-green to red. So the ratiometric fluorescence probe could be utilized for sensitive and selective detection of TYR activity. There was a good linear relationship between the ratiometric fluorescence intensity and TYR concentration in the range of 0.05-5.0 μg mL(-1), with the detection limit of 0.02 μg mL(-1). Significantly, the ratiometric fluorescence probe has been used to fabricate paper-based test strips for visual detection of TYR activity, which validates the potential on-site application.

  2. High extensibility of stress fibers revealed by in vitro micromanipulation with fluorescence imaging

    SciTech Connect

    Matsui, Tsubasa S.; Sato, Masaaki; Deguchi, Shinji

    2013-05-10

    Highlights: •We isolate contractile stress fibers from vascular smooth muscle cells. •We measure the extensibility of individual stress fibers. •We present the first direct evidence that individual stress fibers are highly extensible. •We quantitatively determine the local strain along the length of stress fibers. •The high extensibility we found is beyond that explained by a conventional model. -- Abstract: Stress fibers (SFs), subcellular bundles of actin and myosin filaments, are physically connected at their ends to cell adhesions. The intracellular force transmitted via SFs plays an essential role in cell adhesion regulation and downstream signaling. However, biophysical properties intrinsic to individual SFs remain poorly understood partly because SFs are surrounded by other cytoplasmic components that restrict the deformation of the embedded materials. To characterize their inherent properties independent of other structural components, we isolated SFs from vascular smooth muscle cells and mechanically stretched them by in vitro manipulation while visualizing strain with fluorescent quantum dots attached along their length. SFs were elongated along their entire length, with the length being approximately 4-fold of the stress-free length. This surprisingly high extensibility was beyond that explained by the tandem connection of actin filaments and myosin II bipolar filaments present in SFs, thus suggesting the involvement of other structural components in their passive biophysical properties.

  3. High-efficiency and long-lifetime fluorescent blue organic-emitting device

    NASA Astrophysics Data System (ADS)

    Ho, Yu-Hsuan; Lin, Tien-Chun; Wu, Chia-Fang; Lee, Jiun-Haw

    2006-08-01

    In this paper, We have demonstrated a blue fluorescent organic light-emitting device (OLED) with a current efficiency of 19.2 cd/A at 100 cd/m2, an estimated half-lifetime of 15611 hours at an initial luminance of 1000 cd/m2, and a voltage of 4.9 V at 20 mA/cm2 with a high electron mobility electron transport layer (ETL) material and high efficiency dopant material. The external quantum efficiency (EQE) in this optimized OLED is 8.32%, which is very close to the theoretical limit. Carrier balance condition is achieved due to the incorporation of the high mobility ETL, bis(10- hydroxyben-zo[h]quinolinato)beryllium (Bebq2), which can not only effectively increase the current efficiency and elongate the operation lifetime, but also reduce the driving voltage and increase the power efficiency. The EML consisted of 4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl (DPAVBi) as the blue dopant and 9,10-bis(2'- naphthyl) anthracene (ADN) as the matrix. We found that the dopant concentration of DPAVBi did not affect the mobility value of the EML which is consistent with the J-V characteristics. Besides, although it is believed the bulk ADN is a kind of HTL materials, we found the electron mobility of ADN is one order of magnitude higher than its hole mobility in our blue OLEDs.

  4. Highly sensitive ratiometric detection of heparin and its oversulfated chondroitin sulfate contaminant by fluorescent peptidyl probe.

    PubMed

    Mehta, Pramod Kumar; Lee, Hyeri; Lee, Keun-Hyeung

    2017-05-15

    The selective and sensitive detection of heparin, an anticoagulant in clinics as well as its contaminant oversulfated chondroitin sulfate (OSCS) is of great importance. We first reported a ratiometric sensing method for heparin as well as OSCS contaminants in heparin using a fluorescent peptidyl probe (Pep1, pyrene-GSRKR) and heparin-digestive enzyme. Pep1 exhibited a highly sensitive ratiometric response to nanomolar concentration of heparin in aqueous solution over a wide pH range (2~11) and showed highly selective ratiometric response to heparin among biological competitors such as hyaluronic acid and chondroitin sulfate. Pep1 showed a linear ratiometric response to nanomolar concentrations of heparin in aqueous solutions and in human serum samples. The detection limit for heparin was calculated to be 2.46nM (R(2)=0.99) in aqueous solutions, 2.98nM (R(2)=0.98) in 1% serum samples, and 3.43nM (R(2)=0.99) in 5% serum samples. Pep1 was applied to detect the contaminated OSCS in heparin with heparinase I, II, and III, respectively. The ratiometric sensing method using Pep1 and heparinase II was highly sensitive, fast, and efficient for the detection of OSCS contaminant in heparin. Pep1 with heparinase II could detect as low as 0.0001% (w/w) of OSCS in heparin by a ratiometric response.

  5. Simultaneous determination of 11 fluorescent whitening agents in food-contact paper and board by ion-pairing high-performance liquid chromatography with fluorescence detection.

    PubMed

    Jiang, Dingguo; Chen, Lisong; Fu, Wusheng; Qiu, Hanquan

    2015-02-01

    4,4'-Diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents (DSD-FWAs) are prohibited in food-contact paper and board in many countries. In this work, a reliable high-performance liquid chromatography method was developed for the simultaneous determination of 11 common DSD-FWAs in paper material. Sample preparation and extraction as well as chromatographic separation of multicomponent DSD-FWAs were successfully optimized. DSD-FWAs in prepared samples were ultrasonically extracted with acetonitrile/water/triethylamine (40:60:1, v/v/v), separated on the C(18) column with the mobile phase containing tetrabutylammonium bromide, and then detected by a fluorescence detector. The limits of detection were 0.12-0.24 mg/kg, and the calibration curves showed the linear correlation (R(2) ≥ 0.9994) within the range of 8.0-100 ng/mL, which was equivalent to the range of 0.80-10 mg/kg in the sample. The average recoveries and the RSDs were 81-106% and 2-9% at two fortification levels (1.0 and 5.0 mg/kg) in paper bowls, respectively. The successful determination of 11 DSD-FWAs in food-contact paper and board obtained from local markets indicated that the newly developed method was rapid, accurate, and highly selective.

  6. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    NASA Astrophysics Data System (ADS)

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-05-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min‑1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability.

  7. Influence of age on reactivity to diverse emotional challenges in low- and high-anxiety rats.

    PubMed

    de Oliveira, Luciana C; Gomes, Margareth Z; Brandão, Marcus L

    2011-02-01

    Studies have revealed that the extent of reactivity of high-anxiety rats to diverse challenges is different than low-anxiety rats and have provided important insights into the psychopathology of anxiety. Various factors intervene to allow defensive mechanisms to react to diverse threatening challenges, including ontogeny and the nature of the emotional challenge (e.g., conditioned vs. unconditioned). The present study investigated the extent to which a particular type of fear extrapolates to other emotional responses to diverse threatening challenges. Groups of 30- and 60-day-old rats were assigned to low freezing behavior (LFB) and high freezing behavior (HFB) groups using the contextual fear conditioning paradigm and subjected to either the fear-potentiated startle (FPS) test, novelty-induced ultrasound vocalizations (USVs) or elevated plus-maze (EPM) tests. At 30 days of age, HFB rats exhibited greater FPS than LFB rats. In contrast, prior selection of HFB and LFB did not affect the performance of 30-day-old animals in the EPM and novelty-induced USVs. Sixty-day-old animals exhibited a performance deficit in all three tests. These data suggest that the performance of young rats in animal models of anxiety parallels their selection as LFB and HFB in the contextual fear conditioning paradigm. However, the increased fear-like behavior exhibited by the 60-day-old HFB rats may elicit performance deficits in conditioned and unconditioned fear tests. These results suggest that the interaction between hyperanxiety and age may cause a performance deficit despite the animals' increased fear-like behavior when facing emotional challenges, thus resembling psychiatric patients in many respects.

  8. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    PubMed Central

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-01-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min−1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability. PMID:27147586

  9. Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling using High-Performance Computing

    SciTech Connect

    Hammond, Glenn E.; Lichtner, Peter C.; Lu, Chuan

    2007-08-01

    Numerical modeling has become a critical tool to the Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most “state of the art” groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers and has exhibited impressive strong scalability on up to 4000 processors on the ORNL Cray XT3. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies where overly-simplistic historical modeling erroneously predicted decade removal times for uranium by ambient groundwater flow. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.

  10. Key Structural Elements of Unsymmetrical Cyanine Dyes for Highly Sensitive Fluorescence Turn-On DNA Probes.

    PubMed

    Uno, Kakishi; Sasaki, Taeko; Sugimoto, Nagisa; Ito, Hideto; Nishihara, Taishi; Hagihara, Shinya; Higashiyama, Tetsuya; Sasaki, Narie; Sato, Yoshikatsu; Itami, Kenichiro

    2017-01-17

    Unsymmetrical cyanine dyes, such as thiazole orange, are useful for the detection of nucleic acids with fluorescence because they dramatically enhance the fluorescence upon binding to nucleic acids. Herein, we synthesized a series of unsymmetrical cyanine dyes and evaluated their fluorescence properties. A systematic structure-property relationship study has revealed that the dialkylamino group at the 2-position of quinoline in a series of unsymmetrical cyanine dyes plays a critical role in the fluorescence enhancement. Four newly designed unsymmetrical cyanine dyes showed negligible intrinsic fluorescence in the free state and strong fluorescence upon binding to double-stranded DNA (dsDNA) with a quantum yield of 0.53 to 0.90, which is 2 to 3 times higher than previous unsymmetrical cyanine dyes. A detailed analysis of the fluorescence lifetime revealed that the dialkylamino group at the 2-position of quinoline suppressed nonradiative decay in favor of increased fluorescence quantum yield. Moreover, these newly developed dyes were able to stain the nucleus specifically in fixed HeLa cells examined by using a confocal laser-scanning microscope.

  11. Influence of nitrogen admixture to argon on the ion energy distribution in reactive high power pulsed magnetron sputtering of chromium

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; Hecimovic, A.; von Keudell, A.

    2017-04-01

    Reactive high power impulse magnetron sputtering (HiPIMS) of metals is of paramount importance for the deposition of various oxides, nitrides and carbides. The addition of a reactive gas such as nitrogen to an argon HiPIMS plasma with a metal target allows the formation of the corresponding metal nitride on the substrate. The addition of a reactive gas introduces new dynamics into the plasma process, such as hysteresis, target poisoning and the rarefaction of two different plasma gases. We investigate the dynamics for the deposition of chromium nitride by a reactive HiPIMS plasma using energy- and time-resolved ion mass spectrometry, fast camera measurements and temporal and spatially resolved optical emission spectroscopy. It is shown that the addition of nitrogen to the argon plasma gas significantly changes the appearance of the localized ionization zones, the so-called spokes, in HiPIMS plasmas. In addition, a very strong modulation of the metal ion flux within each HiPIMS pulse is observed, with the metal ion flux being strongly suppressed and the nitrogen molecular ion flux being strongly enhanced in the high current phase of the pulse. This behavior is explained by a stronger return effect of the sputtered metal ions in the dense plasma above the racetrack. This is best observed in a pure nitrogen plasma, because the ionization zones are mostly confined, implying a very high local plasma density and consequently also an efficient scattering process.

  12. Low-cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence Detection

    DTIC Science & Technology

    2012-04-01

    Johnson , M.A.L.; Yu, Shonghai; Kolbas, R. M.; Cook , Jr. J. W.; Schetzina, J. F. Absorption Coefficient and...absorption region to achieve high QE 0 200 400 600 800 1000 GaN E F ie ld (M V /c m ) E n e rg y Distance (nm) E c E v SiC 0.0 1.0 2.0 3.0 1 2 575 580...585 E n e rg y E le c tr ic F ie ld ( M V /c m ) Distance (nm) 0 200 400 600 800 1000 Mg Doped ICCL GaN E F ie ld (M V /c m ) E n e rg y

  13. Highly luminescent N-doped carbon quantum dots as an effective multifunctional fluorescence sensing platform.

    PubMed

    Qian, Zhaosheng; Ma, Juanjuan; Shan, Xiaoyue; Feng, Hui; Shao, Linxiang; Chen, Jianrong

    2014-02-17

    The doping of carbon quantum dots with nitrogen provides a promising direction to improve fluorescence performance and broaden their applications in sensing systems. Herein we report a one-pot solvothermal synthesis of N-doped carbon quantum dots (NCQDs) and the synthesis of a series of NCQDs with different nitrogen contents. The as-prepared NCQDs were compared with carbon quantum dots (CQDs); the introduction of nitrogen atoms largely increased the quantum yield of NCQDs and highest emission efficiency is up to 36.3 %. The fluorescence enhancement may originate from more polyaromatic structures induced by incorporated nitrogen atoms and protonation of nitrogen atoms on dots. It was found that NCQDs can act as a multifunctional fluorescence sensing platform because they can be used to detect pH values, Ag(I), and Fe(III) in aqueous solution. The fluorescence intensity of NCQDs is inversely proportional to pH values across a broad range from 5.0 to 13.5, which indicates that NCQDs can be devised as an effective pH indicator. Selective detection of Ag(I) and Fe(III) was achieved based on their distinctive fluorescence influence because Ag(I) can significantly enhance the fluorescence whereas Fe(III) can greatly quench the fluorescence. The quantitative determination of Ag(I) can be accomplished with NCQDs by using the linear relationship between fluorescence intensity of NCQDs and concentration of Ag(I). The sensitive detection of H2O2 was developed by taking advantage of the distinct quenching ability of Fe(III) and Fe(II) toward the fluorescence of NCQDs. Cellular toxicity test showed NCQDs still retain low toxicity to cells despite the introduction of a great deal of nitrogen atoms. Moreover, bioimaging experiments demonstrated that NCQDs have stronger resistance to photobleaching than CQDs and more excellent fluorescence labeling performance.

  14. High impact strength polymers having novel nano-structures produced via reactive extrusion

    NASA Astrophysics Data System (ADS)

    Tortorella, Nathan Fraser

    A major focus of scientists and engineers over the last century has been to increase the impact strength and therefore reduce the brittleness of materials. By altering and adding energy absorption mechanisms, brittle failure can be averted. Isotactic polypropylene (PP) is the focus of this dissertation because it is an extremely low cost, high volume, versatile plastic but behaves in a brittle manner at or below room temperature or in a notched state. Early work on impact modification of polypropylene focused on blending energy-absorbing low density elastomers and rubbers. These binary blends all had a common problem---an increase in impact strength was paralleled by a significant decrease in both elastic modulus and yield stress. Reactive extrusion processing has allowed the in-situ compatibilization of isotactic polypropylene and metallocene-catalyzed ethylene-octene copolymers (EOCs). This process involves combining both the comonomer and vector fluid approaches to grafting polyolefins. Styrene monomer and a multifunctional acrylate monomer undergo peroxide-induced copolymerization and grafting in the presence of both PP and EOC. This results in a phase separated alloy with an impact strength over 13 times that of pure polypropylene and double that of the physical blend. There is also a significant improvement in stress-strain performance when comparing the alloys to physical blend counterparts. Many researchers have categorized the necessary components to toughening polypropylene as pertaining to the amorphous phase. The alloys described in this dissertation meet the criteria put forth by these researchers, namely low density, crystallinity, and modulus of the elastomer phase, sub-micron particle diameter, close inter-particle distance, and a high degree of entanglements of both the PP matrix phase and EOC minor phase. But many people neglect to study the crystalline state of impact modified PP in conjunction with the amorphous phase. This work shows that the

  15. A high-throughput fluorescence resonance energy transfer-based assay for DNA ligase.

    PubMed

    Shapiro, Adam B; Eakin, Ann E; Walkup, Grant K; Rivin, Olga

    2011-06-01

    DNA ligase is the enzyme that catalyzes the formation of the backbone phosphodiester bond between the 5'-PO(4) and 3'-OH of adjacent DNA nucleotides at single-stranded nicks. These nicks occur between Okazaki fragments during replication of the lagging strand of the DNA as well as during DNA repair and recombination. As essential enzymes for DNA replication, the NAD(+)-dependent DNA ligases of pathogenic bacteria are potential targets for the development of antibacterial drugs. For the purposes of drug discovery, a high-throughput assay for DNA ligase activity is invaluable. This article describes a straightforward, fluorescence resonance energy transfer-based DNA ligase assay that is well suited for high-throughput screening for DNA ligase inhibitors as well as for use in enzyme kinetics studies. Its use is demonstrated for measurement of the steady-state kinetic constants of Haemophilus influenzae NAD(+)-dependent DNA ligase and for measurement of the potency of an inhibitor of this enzyme.

  16. Analysis of serotonin concentrations in human milk by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Chiba, Takeshi; Maeda, Tomoji; Tairabune, Tomohiko; Tomita, Takashi; Sanbe, Atsushi; Takeda, Rika; Kikuchi, Akihiko; Kudo, Kenzo

    2017-03-25

    Serotonin (5-hydroxytryptamine, 5-HT) plays an important role in milk volume homeostasis in the mammary gland during lactation; 5-HT in milk may also affect infant development. However, there are few reports on 5-HT concentrations in human breast milk. To address this issue, we developed a simple method based on high-performance liquid chromatography with fluorescence detection (HPLC-FD) for measuring 5-HT concentrations in human breast milk. Breast milk samples were provided by four healthy Japanese women. Calibration curves for 5-HT in each sample were prepared with the standard addition method between 5 and 1000 ng/ml, and all had correlation coefficients >0.999. The recovery of 5-HT was 96.1%-101.0%, with a coefficient of variation of 3.39%-8.62%. The range of 5-HT concentrations estimated from the calibration curves was 11.1-51.1 ng/ml. Thus, the HPLC-FD method described here can effectively extract 5-HT from human breast milk with high reproducibility.

  17. A High Affinity Red Fluorescence and Colorimetric Probe for Amyloid β Aggregates

    NASA Astrophysics Data System (ADS)

    Rajasekhar, K.; Narayanaswamy, Nagarjun; Murugan, N. Arul; Kuang, Guanglin; Ågren, Hans; Govindaraju, T.

    2016-04-01

    A major challenge in the Alzheimer’s disease (AD) is its timely diagnosis. Amyloid β (Aβ) aggregates have been proposed as the most viable biomarker for the diagnosis of AD. Here, we demonstrate hemicyanine-based benzothiazole-coumarin (TC) as a potential probe for the detection of highly toxic Aβ42 aggregates through switch-on, enhanced (~30 fold) red fluorescence (Emax = 654 nm) and characteristic colorimetric (light red to purple) optical outputs. Interestingly, TC exhibits selectivity towards Aβ42 fibrils compared to other abnormal protein aggregates. TC probe show nanomolar binding affinity (Ka = 1.72 × 107 M‑1) towards Aβ42 aggregates and also displace ThT bound to Aβ42 fibrils due to its high binding affinity. The Aβ42 fibril-specific red-shift in the absorption spectra of TC responsible for the observed colorimetric optical output has been attributed to micro-environment change around the probe from hydrophilic-like to hydrophobic-like nature. The binding site, binding energy and changes in optical properties observed for TC upon interaction with Aβ42 fibrils have been further validated by molecular docking and time dependent density functional theory studies.

  18. Ultra-small, highly stable, and membrane-impermeable fluorescent nanosensors for oxygen

    NASA Astrophysics Data System (ADS)

    Wang, Xu-dong; Stolwijk, Judith A.; Sperber, Michaela; Meier, Robert J.; Wegener, Joachim; Wolfbeis, Otto S.

    2013-09-01

    We report on the preparation of ultra-small fluorescent nanosensors for oxygen via a one-pot approach. The nanoparticles have a hydrophobic core capable of firmly hosting hydrophobic luminescent oxygen probes. Their surface is composed of a dense and long-chain poly(ethylene glycol) shell, which renders them cell-membrane impermeable but yet highly sensitive to oxygen, and also highly stable in aqueous solutions and cell culture media. These features make them potentially suitable for sensing oxygen in extracellular fluids such as blood, interstitial and brain fluid, in (micro) bioreactors and micro- or nanoscale fluidic devices. Four kinds of nanosensors are presented, whose excitation spectra cover a wide spectral range (395-630 nm), thus matching many common laser lines, and with emission maxima ranging from 565 to 800 nm, thereby minimizing interference from background luminescence of biomatter. The unquenched lifetimes are on the order of 5.8-234 μs, which—in turn—enables lifetime imaging and additional background separation via time-gated methods.

  19. Phase transformation and fluorescent enhancement of ErF3 at high pressure

    NASA Astrophysics Data System (ADS)

    Li, Wentao; Ren, Xiangting; Huang, Yanwei; Yu, Zhenhai; Mi, Zhongying; Tamura, Nobumichi; Li, Xiaodong; Peng, Fang; Wang, Lin

    2016-09-01

    Pressure-induced phase transformation and fluorescent properties of ErF3 were investigated here using in-situ synchrotron X-ray diffraction and photoluminescence up to 32.1 GPa at room temperature. Results showed that ErF3 underwent a reversible pressure-induced phase transition from the β-YF3-type to the fluocerite LaF3-type at 9.8 GPa. The bulk moduli B0 for low- and high-pressure phases were determined to be 130 and 208 GPa, respectively. Photoluminescencent studies showed that new emission lines belonging to the transition of 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 appeared during phase transition, suggesting pressure-induced electronic band splitting. Remarkably, significant pressure-induced enhancement of photoluminescence was observed, which was attributed to lattice distortion of the material under high pressure.

  20. A high throughput fluorescent assay for measuring the activity of fatty acid amide hydrolase.

    PubMed

    Kage, Karen L; Richardson, Paul L; Traphagen, Linda; Severin, Jean; Pereda-Lopez, Ana; Lubben, Thomas; Davis-Taber, Rachel; Vos, Melissa H; Bartley, Diane; Walter, Karl; Harlan, John; Solomon, Larry; Warrior, Usha; Holzman, Thomas F; Faltynek, Connie; Surowy, Carol S; Scott, Victoria E

    2007-03-30

    Fatty acid amide hydrolase (FAAH) is the enzyme responsible for the rapid degradation of fatty acid amides such as the endocannabinoid anandamide. Inhibition of FAAH activity has been suggested as a therapeutic approach for the treatment of chronic pain, depression and anxiety, through local activation of the cannabinoid receptor CB1. We have developed a high throughput screening assay for identification of FAAH inhibitors using a novel substrate, decanoyl 7-amino-4-methyl coumarin (D-AMC) that is cleaved by FAAH to release decanoic acid and the highly fluorescent molecule 7-amino-4-methyl coumarin (AMC). This assay gives an excellent signal window for measuring FAAH activity and, as a continuous assay, inherently offers improved sensitivity and accuracy over previously reported endpoint assays. The assay was validated using a panel of known FAAH inhibitors and purified recombinant human FAAH, then converted to a 384 well format and used to screen a large library of compounds (>600,000 compounds) to identify FAAH inhibitors. This screen identified numerous novel FAAH inhibitors of diverse chemotypes. These hits confirmed using a native FAAH substrate, anandamide, and had very similar rank order potency to that obtained using the D-AMC substrate. Collectively these data demonstrate that D-AMC can be successfully used to rapidly and effectively identify novel FAAH inhibitors for potential therapeutic use.

  1. HIGH RESOLUTION X-RAY FLUORESCENCE MICRO-TOMOGRAPHY ON SINGLE SEDIMENT PARTICLES.

    SciTech Connect

    VINCZE,L.; VEKEMANS,B.; SZALOKI,I.; JANSSENS,K.; VAN GRIEKEN,R.; FENG,H.; JONES,K.W.; ADAMS,F.

    2002-07-29

    This work focuses on the investigation of the distribution of contaminants in individual sediment particles from the New York/New Jersey Harbor. Knowledge of the spatial distribution of the contaminants within the particles is needed to enable (1) more sophisticated approaches to the understanding of the fate and transport of the contaminants in the environment and (2) more refined methods for cleaning the sediments. The size of the investigated particles ranges from 30-80 microns. Due to the low concentration of the elements of interest and the microscopic size of the environmental particles in these measurements, the small size and high intensity of the analyzing X-ray beam was critical. The high photon flux at the ESRF Microfocus beam line (ID13) was used as the basis for fluorescence tomography to investigate whether the inorganic compounds are taken upon the surface organic coating or whether they are distributed through the volume of the grains being analyzed. The experiments were done using a 13 keV monochromatic beam of approximately 2 {micro}m in size having an intensity of 10{sup 10} ph/s, allowing absolute detection limits on the 0.04-1 fg level for Ti, Cr, Mn, Fe, Ni, and Zn.

  2. A Manganese Catalyst for Highly Reactive Yet Chemoselective Intramolecular C(sp3)—H Amination

    PubMed Central

    Paradine, Shauna M.; Griffin, Jennifer R.; Zhao, Jinpeng; Petronico, Aaron L.; Miller, Shannon M.; White, M. Christina

    2016-01-01

    C—H bond oxidation reactions underscore the existing paradigm wherein high reactivity and high selectivity are inversely correlated. The development of catalysts capable of oxidizing strong aliphatic C(sp3)—H bonds while displaying chemoselectivity (i.e. tolerance of more oxidizable functionality) remains an unsolved problem. Herein, we describe a catalyst, manganese tert-butylphthalocyanine [Mn(tBuPc)], that is an outlier to the reactivity-selectivity paradigm. It is unique in its capacity to functionalize all types of C(sp3)—H bonds intramolecularly, while displaying excellent chemoselectivity in the presence of π-functionality. Mechanistic studies indicate that [Mn(tBuPc)] transfers bound nitrenes to C(sp3)—H bonds via a pathway that lies between concerted C—H insertion, observed with reactive noble metals (e.g. rhodium), and stepwise radical C—H abstraction/rebound, observed with chemoselective base metals (e.g. iron). Rather than achieving a blending of effects, [Mn(tBuPc)] aminates even 1° aliphatic and propargylic C—H bonds, reactivity and selectivity unusual for previously known catalysts. PMID:26587714

  3. A convenient and label-free fluorescence "turn off-on" nanosensor with high sensitivity and selectivity for acid phosphatase.

    PubMed

    Liu, Ziping; Lin, Zihan; Liu, Linlin; Su, Xingguang

    2015-05-30

    In this study, we reported a convenient label-free fluorescence nanosensor for rapid detection of acid phosphatase on the basis of aggregation-caused quenching (ACQ) and enzymolysis approach. The selectivity nanosensor was based on the fluorescence "turn off-on" mode, which possessed high sensitivity features. The original strong fluorescence intensity of CuInS2 QDs was quenched by sodium hexametaphosphate (NaPO3)6. The high efficiency of the quenching was caused by the non-covalent binding of positively charged CuInS2 QDs to the negatively charged (NaPO3)6 through electrostatic interactions, aggregating to form a CuInS2 QDs/(NaPO3)6 complex. Adding acid phosphatase caused intense fluorescence of CuInS2 QDs/(NaPO3)6 to be recovered, and this was because of enzymolysis. (NaPO3)6 was hydrolyzed into small fragments and the high negative charge density decreased, which would weaken the strong electrostatic interactions. As a result, the quenched fluorescence "turned on". Under the optimum conditions, there was a good linear relationship between I/I0 (I and I0 were the fluorescence intensity of CuInS2 QDs/(NaPO3)6 system in the presence and absence of acid phosphatase, respectively) and acid phosphatase concentration in the range of 75-1500 nU mL(-1) with the detection limit of 9.02 nU mL(-1). The proposed nanosensor had been utilized to detect and accurately quantify acid phosphatase in human serum samples with satisfactory results.

  4. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    SciTech Connect

    Su, Hui

    2001-01-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, the author introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, they demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection. In the second part of this dissertation, the author used laser-induced native fluorescence coupled with capillary electrophoresis (LINF-CE) and microscope imaging to study the single cell degranulation. On the basis of good temporal correlation with events observed through an optical microscope, they have identified individual peaks in the fluorescence electropherograms as serotonin released from the granular core on contact with the surrounding fluid.

  5. Remarkably high activities of testicular cytochrome c in destroying reactive oxygen species and in triggering apoptosis

    PubMed Central

    Liu, Zhe; Lin, Hao; Ye, Sheng; Liu, Qin-ying; Meng, Zhaohui; Zhang, Chuan-mao; Xia, Yongjing; Margoliash, Emanuel; Rao, Zihe; Liu, Xiang-jun

    2006-01-01

    Hydrogen peroxide (H2O2) is the major reactive oxygen species (ROS) produced in sperm. High concentrations of H2O2 in sperm induce nuclear DNA fragmentation and lipid peroxidation and result in cell death. The respiratory chain of the mitochondrion is one of the most productive ROS generating systems in sperm, and thus the destruction of ROS in mitochondria is critical for the cell. It was recently reported that H2O2 generated by the respiratory chain of the mitochondrion can be efficiently destroyed by the cytochrome c-mediated electron-leak pathway where the electron of ferrocytochrome c migrates directly to H2O2 instead of to cytochrome c oxidase. In our studies, we found that mouse testis-specific cytochrome c (T-Cc) can catalyze the reduction of H2O2 three times faster than its counterpart in somatic cells (S-Cc) and that the T-Cc heme has the greater resistance to being degraded by H2O2. Together, these findings strongly imply that T-Cc can protect sperm from the damages caused by H2O2. Moreover, the apoptotic activity of T-Cc is three to five times greater than that of S-Cc in a well established apoptosis measurement system using Xenopus egg extract. The dramatically stronger apoptotic activity of T-Cc might be important for the suicide of male germ cells, considered a physiological mechanism that regulates the number of sperm produced and eliminates those with damaged DNA. Thus, it is very likely that T-Cc has evolved to guarantee the biological integrity of sperm produced in mammalian testis. PMID:16757556

  6. High-sensitivity C-reactive protein in paediatric inflammatory bowel disease

    PubMed Central

    Sidoroff, Marianne; Karikoski, Riitta; Raivio, Taneli; Savilahti, Erkki; Kolho, Kaija-Leena

    2010-01-01

    AIM: To study whether high-sensitivity C-reactive protein (hs-CRP) measurement can aid the assessment of disease activity and glucocorticoid treatment in paediatric inflammatory bowel disease (IBD). METHODS: CRP levels were measured in 39 children with IBD undergoing colonoscopy [median age 12.8 years, Crohn’s disease (CD) n = 20], in 22 other children with IBD followed for acute response to glucocorticoids, and in 33 paediatric non-IBD patients. When standard CRP level was below detection limit (< 5 mg/L), hs-CRP was analyzed. RESULTS: Sixty-four percent (25/39) of the children with IBD undergoing colonoscopy displayed undetectable (< 5 mg/L) standard CRP levels. Of these, the hs-CRP measurement could not differentiate between active (median, 0.2 mg/L, range, 0.007-1.37, n = 17) or quiescent (0.1 mg/L, 0.01-1.89, n = 8, P = NS) disease. Patients with ileocolonic CD had higher CRP levels (14 mg/L, 0.06-45, n = 13) than patients with no ileal involvement (0.18 mg/L, 0.01-9, n = 7, P < 0.01) or ulcerative colitis (UC) (0.13 mg/L, 0.007-23, P < 0.05). In children with active IBD treated with systemic glucocorticoids, the standard CRP was undetectable in 59% of the patients. The hs-CRP levels did not differ between patients that responded to steroid therapy and in non-responders. CONCLUSION: The measurement of hs-CRP did not prove useful in the assessment of disease activity or glucocorticoid treatment in paediatric IBD patients that had undetectable standard CRP. PMID:20556836

  7. Fluorescence determination of N-acetylaspartic acid in the rat cerebrum homogenate using high-performance liquid chromatography with pre-column fluorescence derivatization.

    PubMed

    Fukushima, Takeshi; Arai, Kotaro; Tomiya, Masayuki; Mitsuhashi, Shogo; Sasaki, Tsukasa; Santa, Tomofumi; Imai, Kazuhiro; Toyo'oka, Toshimasa

    2008-01-01

    N-acetyl-L-aspartic acid (NAA) is an endogenous compound, and its brain concentration is suggested to be altered in neurological disorders. In the present study, a fluorescence determination method for NAA was developed by employing reversed-phase high-performance liquid chromatography (HPLC) with pre-column fluorescence derivatization using 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Using methylsuccinic acid as the internal standard, a linear calibration curve for NAA was constructed in the range 125-1000 microM (n=3). The detection limit on the column was approximately 5.0 fmol (signal-to-noise ratio 3). The proposed HPLC method was applied to determine NAA in the rat cerebrum homogenate. Cerebrum NAA was successfully determined using 10 microL of the homogenate, and the validation data for the proposed HPLC method demonstrated satisfactory results. Intra- and inter-day precision and accuracy were within 1.1-7.0 and -8.1-6.3%, respectively. The concentration of NAA in the male rat cerebrum (13 weeks old) was 84 +/-4.6 nmol/mg protein (n = 3) [corrected].

  8. Chemical reactivity of CVC and CVD SiC with UO2 at high temperatures

    NASA Astrophysics Data System (ADS)

    Silva, Chinthaka M.; Katoh, Yutai; Voit, Stewart L.; Snead, Lance L.

    2015-05-01

    Two types of silicon carbide (SiC) synthesized using two different vapor deposition processes were embedded in UO2 pellets and evaluated for their potential chemical reaction with UO2. While minor reactivity between chemical-vapor-composited (CVC) SiC and UO2 was observed at comparatively low temperatures of 1100 and 1300 °C, chemical-vapor-deposited (CVD) SiC did not show any such reactivity. However, both CVD and CVC SiCs showed some reaction with UO2 at a higher temperature (1500 °C). Elemental maps supported by phase maps obtained using electron backscatter diffraction indicated that CVC SiC was more reactive than CVD SiC at 1500 °C. Furthermore, this investigation indicated the formation of uranium carbides and uranium silicide chemical phases such as UC, USi2, and U3Si2 as a result of SiC reaction with UO2.

  9. 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.

  10. 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%.

  11. A highly selective fluorescent probe based on coumarin for the imaging of N2H4 in living cells

    NASA Astrophysics Data System (ADS)

    Chen, Song; Hou, Peng; Wang, Jing; Liu, Lei; Zhang, Qi

    2017-02-01

    A turn-on fluorescence probe for highly sensitive and selective detection of N2H4 was developed based on hydrazine-triggered a substitution- cyclization-elimination cascade. Upon the treatment with N2H4, probe 1, 4-methyl-coumarin-7-yl bromobutanoate, displayed a remarkable fluorescence enhancement (25-fold) with a maximum at 450 nm. This probe can quantitatively detect N2H4 with a extremely low detection limit as 7 × 10- 8 M. Moreover, cell imaging experiments have indicated that probe 1 has potential ability to detect and image N2H4 in biological systems.

  12. A new half-condensed Schiff base compound: highly selective and sensitive pH-responsive fluorescent sensor.

    PubMed

    Saha, Uday Chand; Dhara, Koushik; Chattopadhyay, Basab; Mandal, Sushil Kumar; Mondal, Swastik; Sen, Supriti; Mukherjee, Monika; van Smaalen, Sander; Chattopadhyay, Pabitra

    2011-09-02

    A new probe, 3-[(3-benzyloxypyridin-2-ylimino)methyl]-2-hydroxy-5-methylbenzaldehyde (1-H) behaves as a highly selective fluorescent pH sensor in a Britton-Robinson buffer at 25 °C. The pH titrations show a 250-fold increase in fluorescence intensity within the pH range of 4.2 to 8.3 with a pK(a) value of 6.63 which is valuable for studying many of the biological organelles.

  13. Highly selective and sensitive fluorescence chemosensor for the detection of palladium species based on Tsuji-Trost reaction.

    PubMed

    Xu, Zhong-Yong; Li, Jing; Guan, Su; Zhang, Lei; Dong, Chang-Zhi

    2015-09-05

    A new chemosensor 7-nitro-2,1,3-benzoxadiazole-4-allyl-N-(thiophen-2-ylmethyl)carbamate (NBDTC) was synthesized and utilized for palladium detection based on the Tsuji-Trost reaction. NBDTC displayed specific and ratiometric fluorescent responses toward palladium species. The chemosensor showed more than 50-fold enhancement in fluorescence intensity with the presence of PEG400 and palladium because NBDTC can be transformed to NBDT under palladium-catalyzing Tsuji-Trost reaction. NBDTC displayed high selectivity and sensitivity for palladium species with the detection limit of 1.13×10(-9) M.

  14. Rhodamine 6G hydrazone bearing thiophene unit: A highly sensitive and selective off-on fluorescent chemosensor for Al3+

    NASA Astrophysics Data System (ADS)

    Wu, Wei-Na; Mao, Pan-Dong; Wang, Yuan; Zhao, Xiao-Lei; Jia, Lei; Xu, Zhou-Qing

    2016-10-01

    A rhodamine derivative (R1) has been synthesized by a hydrazone formation of rhodamine 6G hydrazide with 3-methylthiophene-2-carbaldehyde, which exhibits high selectivity and sensitivity as an "off-on" fluorescent sensor toward Al3+ in water containing media. The binding process was confirmed by UV-vis absorption, fluorescence measurements, mass spectroscopy and DFT calculation. The probe functions by Al3+ induced hydrolytic cleavage of the imine-bond to produce an intense rhodamine-based emission. To test the practical use of the probe, the determination of Al3+ in real water samples was also evaluated.

  15. High sensitivity fluorescent single particle and single molecule detection apparatus and method

    DOEpatents

    Mathies, Richard A.; Peck, Konan; Stryer, Lubert

    1990-01-01

    Apparatus is described for ultrasensitive detection of single fluorescent particles down to the single fluorescent molecule limit in a fluid or on a substrate comprising means for illuminating a predetermined volume of the fluid or area of the substrate whereby to emit light including background light from the fluid and burst of photons from particles residing in the area. The photon burst is detected in real time to generate output representative signal. The signal is received and the burst of energy from the fluorescent particles is distinguished from the background energy to provide an indication of the number, location or concentration of the particles or molecules.

  16. High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy.

    PubMed

    Guo, Baoshan; Lei, Cheng; Ito, Takuro; Jiang, Yiyue; Ozeki, Yasuyuki; Goda, Keisuke

    2016-01-01

    The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel) within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy-a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary) and nitrogen-deficient (lipid-accumulated) E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production.

  17. High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy

    PubMed Central

    Guo, Baoshan; Lei, Cheng; Ito, Takuro; Jiang, Yiyue; Ozeki, Yasuyuki; Goda, Keisuke

    2016-01-01

    The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel) within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy–a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary) and nitrogen-deficient (lipid-accumulated) E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production. PMID:27846239

  18. Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

    DOEpatents

    Kao, Hung Pin; Schoeniger, Joseph; Yang, Nancy

    2001-01-01

    A technique for increasing the excitation and collection of evanescent fluorescence radiation emanating from a fiber optic sensor having a high refractive index (n.sub.r), dielectric thin film coating has been disclosed and described. The invention comprises a clad optical fiber core whose cladding is removed on a distal end, the distal end coated with a thin, non-porous, titanium dioxide sol-gel coating. It has been shown that such a fiber will exhibit increased fluorescence coupling due in part by 1) increasing the intensity of the evanescent field at the fiber core surface by a constructive interference effect on the propagating light, and 2) increasing the depth of penetration of the field in the sample. The interference effect created by the thin film imposes a wavelength dependence on the collection of the fluorescence and also suggests a novel application of thin films for color filtering as well as increasing collected fluorescence in fiber sensors. Collected fluorescence radiation increased by up to 6-fold over that of a bare fused silica fiber having a numerical aperture (N.A.) of O.6.

  19. 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

  20. A Validated High-Throughput Fluorometric Method for Determination of Omeprazole in Quality Control Laboratory via Charge Transfer Sensitized Fluorescence.

    PubMed

    Mahmoud, Ashraf M; Ahmed, Sameh A

    2016-03-01

    A high-throughput 96-microwell plate fluorometric method was developed and validated to determine omeprazole (OMZ) in its dosage forms. The method was based on the charge-transfer (CT) sensitized fluorescence reaction of OMZ with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ). This fluorescence reaction provided a new approach for simple, sensitive and selective determinations of OMZ in pharmaceutical preparations. In the present method, the fluorescence reaction was carried out in 96-microwell plates as reaction vessels in order to increase the automation of the methodology and the efficiency of its use in quality control laboratories. All factors affecting the fluorescence reaction were carefully studied and the conditions were optimized. The stoichiometry of the fluorescence reaction between OMZ and DDQ was determined and the reaction mechanism was suggested. Under the optimum conditions, the linear range was 100-6000 ng/ml with the lowest LOD of 33 ng/ml. Analytical performance of the proposed assay, in terms of accuracy and precision, was statistically validated and the results were satisfactory; RSD was <2.6 % and the accuracy was 98.6-101.6 %. The method was successfully applied to the analysis of OMZ in its dosage forms; the recovery values were 98.26-99.60 ± 0.95-2.22 %. The developed methodology may provide a safer, automated and economic tool for the analysis of OMZ in quality control laboratories.

  1. Nanopore reactive adsorbents for the high-efficiency removal of waste species

    DOEpatents

    Yang, Arthur Jing-Min; Zhang, Yuehua

    2005-01-04

    A nanoporous reactive adsorbent incorporates a relatively small number of relatively larger reactant, e.g., metal, enzyme, etc., particles (10) forming a discontinuous or continuous phase interspersed among and surrounded by a continuous phase of smaller adsorbent particles (12) and connected interstitial pores (14) therebetween. The reactive adsorbent can effectively remove inorganic or organic impurities in a liquid by causing the liquid to flow through the adsorbent. For example, silver ions may be adsorbed by the adsorbent particles (12) and reduced to metallic silver by reducing metal, such as ions, as the reactant particles (10). The column can be regenerated by backwashing with the liquid effluent containing, for example, acetic acid.

  2. Substituent and Solvent Effects on Excited State Charge Transfer Behavior of Highly Fluorescent Dyes Containing Thiophenylimidazole-Based Aldehydes

    NASA Technical Reports Server (NTRS)

    Santos, Javier; Bu, Xiu R.; Mintz, Eric A.

    2001-01-01

    The excited state charge transfer for a series of highly fluorescent dyes containing thiophenylimidazole moiety was investigated. These systems follow the Twisted Intramolecular Charge Transfer (TICT) model. Dual fluorescence was observed for each substituted dye. X-ray structures analysis reveals a twisted ground state geometry for the donor substituted aryl on the 4 and 5 position at the imidazole ring. The excited state charge transfer was modeled by a linear solvation energy relationship using Taft's pi and Dimroth's E(sub T)(30) as solvent parameters. There is linear relation between the energy of the fluorescence transition and solvent polarity. The degree of stabilization of the excited state charge transfer was found to be consistent with the intramolecular molecular charge transfer. Excited dipole moment was studied by utilizing the solvatochromic shift method.

  3. A Highly Sensitive Fluorescent Sensor for Palladium and Direct Imaging of Its Ecotoxicity in Living Model Organisms.

    PubMed

    Liu, Fei; Du, Juan; Xu, Meiying; Sun, Guoping

    2016-01-01

    Rhodamine is an ideal platform for fluorescence probes owing to its spiro-lactam framework and excellent photochemical properties. Herein, a novel rhodamine-based palladium fluorescent chemosensor, Rd-Eb, showing a fast response time (3 min), high sensitivity for palladium species over other ions, and a low detection limit (1.91×10(-7)  m), was synthesized. It can act as an obvious colorimetric as well as a fluorescent "off/on" sensor for Pd(2+) . In addition, it is also an excellent sensor for in vivo imaging of Pd(2+) in zebra fish and Daphnia magna, illuminating the impact of palladium on organisms at different growth stages with respect to biological toxicology.

  4. 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.

  5. High resolution coral records of reactive and micronutrient trace metals: Monitoring biological responses to flood plumes.

    NASA Astrophysics Data System (ADS)

    Wyndham, T. D.; McCulloch, M. T.; Decarlo, E. H.

    2004-12-01

    The influences of flood plumes on the coastal ocean are difficult to investigate because they are intermittent, transient and highly variable in nature. The application of trace metals in coral carbonates as proxy recorders of marine environmental conditions has been demonstrated as an excellent method for overcoming these difficulties. Coral records of trace metals have been widely used to provide historical records of physical impacts of flood plumes such changing salinity (δ O18), sediment load (Ba) and anthropogenic inputs such as heavy metal pollution (eg. Pb, Cd). Despite successful applications to physical properties, the use of coral records to monitoring the biologic responses to these changing environmental conditions has proved more difficult. With improvements in analytical techniques however, it is now possible to investigate coral records of reactive (rare earth elements) and micronutrient (eg Mn, Zn and Cu) trace metals, which can be used to more widely explore the biogeochemical implications of flood plumes to the coastal ocean. We have obtained high resolution temporal records of rare earth elements, Cu, Zn, Mn and Sn, from corals from two locations, (1) near Townsville on the Great Barrier Reef (GBR) and (2) Kaneohe Bay on Oahu, Hawaii. Both of these locations often display large phytoplankton blooms following flood events, providing a good opportunity to test the idea that coral records can be used to monitor the biological response to flood plumes. These coral records show significant responses to flood plumes that can only be attributed to biogeochemical cycling that occurs as a result of the flood plume influence, rather than the flood plume itself. Thus a mechanism for exploring the biological response to flood plumes is provided. It has generally proven difficult however, to interpret these coral records without a good understanding of the coastal processes. Therefore we also include evidence from direct trace metal measurements of a

  6. Microelectrophoresis devices with integrated fluorescence detectors and reactors for high-throughput DNA sequencing

    NASA Astrophysics Data System (ADS)

    Soper, Steven A.; Ford, Sean M.; Davies, Jack; Williams, Daryl C.; Cheng, Benxu; Klopf, J. Michael; Calderon, Gina M.; Saile, Volker

    1997-05-01

    This work describes the development of micro-devices for high-throughput DNA sequencing applications. Basically, two research efforts will be discussed; (1) fabrication and characterization of micro-reactors to prepare Sanger chain terminated DNA sequencing fragments on a nanoliter scale and; (2) x-ray photolithography of PMMA substrates for the high aspect ratio preparation of electrophoresis devices. The micro-reactor consisted of a 5'-biotinylated catfish olfactory gene, which was amplified by PCR, and attached to the interior wall of an aminoalkylisilane derivatized fused- silica capillary tube via a streptavidin/biotin linkage. Coverage of the interior capillary wall with biotinylated DNA averaged 77 percent. Stability of the anchored template under pressure and electroosmotic rinsing was favorable, requiring approximately 150 h of continuous rinsing to reduce the coverage by only 50 percent. The capillary micro- reactor was placed inside an air thermocycler to control temperature during Sanger ddNTP chain extension and directly coupled to a capillary separation column filled with a LPA solution via low dead volume capillary interlocks. The complimentary DNA fragments generated in the reactor were heat denatured from the immobilized template and directly injected onto a gel-filled capillary using electropumping for size fractionation and detection using NIR-LIF analysis. The total amount of termination fragments in the 31 nL reactor volume was estimated to be 5.2 X 1013 moles and sequencing was shown to produce read lengths on the order to 400 bases. Work will also be described concerning the development of micro-electrophoresis devices in x-ray sensitive photoresists using LIGA techniques. An electrophoresis device with an integrated fluorescence detector was constructed for the high resolution separation of DNA oligonucleotides. The choice of substrate for the electrophoresis was PMMA, due to its intrinsic low electroosmotic flow. Using x-ray lithography in

  7. New fluorescence imaging probe with high spatial resolution for in vivo applications.

    PubMed

    Bonnans, V; Gharbi, T; Pieralli, C; Wacogne, B; Humbert, Ph

    2004-01-01

    A new fiberized fluorescence imaging probe is presented. This device can potentially be used for a wide range of biological or medical applications. By exploiting the chromatic aberrations of gradient index lenses, the excitation blue or near-UV excitation light is focused on the sample surface, while the red fluorescence signal is efficiently launched back to collecting fibers. The excitation fiber is single mode at the working wavelength so that a resolution of 5 microm is obtained over a scanning area of several square millimeters. Experimental fluorescence images are presented. They concern either self-fabricated fluorescent microsamples or views of leaves that constitute an example of biological tissues analysis. The probe can also be adapted for spectroscopic investigations.

  8. Highly selective "Off-On" fluorescent probe for histidine and its imaging in living cells.

    PubMed

    Chen, Tiantian; Yin, Liyan; Huang, Chusen; Qin, Yiqiao; Zhu, Weiping; Xu, Yufang; Qian, Xuhong

    2015-04-15

    A naphthalimide-based fluorescent probe CP has been synthesized with simple steps. It can selectively and sensitively recognize copper ions (Cu(2+)) in HEPES buffer (50mM, pH 7.2). The fluorescence intensity of CP is linearly proportional to the concentration of Cu(2+) ranging from 0-8.3μM (correlation coefficient R(2)=0.9808). The resulted complex CP@Cu can serve as a turn-on fluorescent probe for the detection of histidine and histidine rich proteins in broad pH application range. Upon the addition of histidine, the fluorescence intensity of CP@Cu exhibits a linear correlation with the concentration of histidine ranging from 0-200μM (correlation coefficient R(2)=0.9912). Moreover, CP@Cu has potential for imaging histidine in vitro experiments and has promise in real sample applications with great validity.

  9. High performance magneto-fluorescent nanoparticles assembled from terbium and gadolinium 1,3-diketones

    PubMed Central

    Zairov, Rustem; Mustafina, Asiya; Shamsutdinova, Nataliya; Nizameev, Irek; Moreira, Beatriz; Sudakova, Svetlana; Podyachev, Sergey; Fattakhova, Alfia; Safina, Gulnara; Lundstrom, Ingemar; Gubaidullin, Aidar; Vomiero, Alberto

    2017-01-01

    Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted. The core composition was optimized for the longitudinal relaxivity to be greater than that of the commercial magnetic resonance imaging (MRI) contrast agents together with high level of Tb(III)-centered luminescence. The tuning of both magnetic and luminescent output of nanoparticles is obtained via the simple variation of lanthanide chelates concentrations in the initial synthetic solution. The exposure of the pheochromocytoma 12 (PC 12) tumor cells and periphery human blood lymphocytes to nanoparticles results in negligible effect on cell viability, decreased platelet aggregation and bright coloring, indicating the nanoparticles as promising candidates for dual magneto-fluorescent bioimaging. PMID:28091590

  10. High performance magneto-fluorescent nanoparticles assembled from terbium and gadolinium 1,3-diketones

    NASA Astrophysics Data System (ADS)

    Zairov, Rustem; Mustafina, Asiya; Shamsutdinova, Nataliya; Nizameev, Irek; Moreira, Beatriz; Sudakova, Svetlana; Podyachev, Sergey; Fattakhova, Alfia; Safina, Gulnara; Lundstrom, Ingemar; Gubaidullin, Aidar; Vomiero, Alberto

    2017-01-01

    Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted. The core composition was optimized for the longitudinal relaxivity to be greater than that of the commercial magnetic resonance imaging (MRI) contrast agents together with high level of Tb(III)-centered luminescence. The tuning of both magnetic and luminescent output of nanoparticles is obtained via the simple variation of lanthanide chelates concentrations in the initial synthetic solution. The exposure of the pheochromocytoma 12 (PC 12) tumor cells and periphery human blood lymphocytes to nanoparticles results in negligible effect on cell viability, decreased platelet aggregation and bright coloring, indicating the nanoparticles as promising candidates for dual magneto-fluorescent bioimaging.

  11. Optimizing the Intralayer and Interlayer Compatibility for High-Efficiency Blue Thermally Activated Delayed Fluorescence Diodes.

    PubMed

    Duan, Chunbo; Fan, Chaochao; Wei, Ying; Han, Fuquan; Huang, Wei; Xu, Hui

    2016-01-29

    A series of phosphine oxide hosts, 4,6-bis(diphenylphosphoryl) dibenzothiophene (DBTDPO) and 4- diphenylphosphoryldibenzothiophene (DBTSPO), and electron transporting materials (ETM), 2-(diphenylphosphoryl)dibenzothiophene sulfone (2DBSOSPO), 3-(diphenylphosphoryl)dibenzothiophene sulfone (3DBSOSPO) and 4-(diphenylphosphoryl)dibenzothiophene sulfone (4DBSOSPO) were developed to support blue thermally activated delayed fluorescence (TADF) devices with high performance through optimizing intralayer and interlayer compatibility of emissive layers. On the basis of the triplet energy of ~3.0 eV for the hosts and ETMs, excitons can be effectively confined on DMAC-DPS. Compared to DBTSPO, DBTDPO can support the excellent distribution uniformity to blue TADF dye bis[4-(9,9-dimethyl-9,10-dihydroacridine) phenyl] sulfone (DMAC-DPS), owing to their configuration similarity; while 3DBSOSPO and 4DBSOSPO are superior in compatibility with the hosts due to the similar molecular polarity or configuration. Through adjusting the molecular configuration, the electrical performance of ETMs can be feasibly tuned, including the excellent electron mobility (μe) by the order of 10(-3) cm(2) V(-1) s(-1). As the result, DBTDPO and 4DBSOSPO endowed their four-layer blue TADF devices with the maximum current efficiency of 33.5 cd A(-1) and the maximum external quantum efficiency more than 17%, which are impressive among the best blue TADF devices. It is showed that intralayer compatibility determines the maximum efficiencies, while interlayer compatibility influences efficiency stability.

  12. A new highly selective fluorescent turn-on chemosensor for cyanide anion.

    PubMed

    Chen, Yabin; Shi, Wei; Hui, Yonghai; Sun, Xinhua; Xu, Linxian; Feng, Lei; Xie, Zhengfeng

    2015-05-01

    A new simple molecule, 2-((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)malononitrile (M1), was synthesized successfully by the Knoevenagel condensation reaction between 2-phenyl-1,2,3-triazole-4-carboxaldehyde and malononitrile. The receptor M1 is highly sensitive and selective to cyanide anion due to the nucleophilic addition of cyanide anion with M1. Distinct changes on UV-vis and fluorescence spectra can be detected with the addition of cyanide anion to the DMSO solution of M1. Optical properties of M1 were scarcely affected by the addition of other common background anions (F(-), Cl(-), Br(-), I(-), SCN(-), OH(-), CO4(2-), H2PO4(-), SO4(2-), HSO4(-), AcO(-), and NO3(-)) under the same condition. The detection limit of CN(-) reaches ~1.43 μM by M1 and the presence of background anions brought very slight interference for the detection of CN(-).

  13. 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.

  14. Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume

    NASA Astrophysics Data System (ADS)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Sethuraman, Mathur Gopalakrishnan; Lee, Yong Rok

    2016-10-01

    Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume (P. mume) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV-vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging.

  15. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    SciTech Connect

    Su, Hui

    2001-01-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection.

  16. Carbon Dots as Nontoxic and High-Performance Fluorescence Imaging Agents

    PubMed Central

    Yang, Sheng-Tao; Wang, Xin; Wang, Haifang; Lu, Fushen; Luo, Pengju G.; Cao, Li; Meziani, Mohammed J.; Liu, Jia-Hui; Liu, Yuanfang; Chen, Min; Huang, Yipu; Sun, Ya-Ping

    2009-01-01

    Fluorescent carbon dots (small carbon nanoparticles with the surface passivated by oligomeric PEG molecules) were evaluated for their cytotoxicity and in vivo toxicity and also for their optical imaging performance in reference to that of the commercially supplied CdSe/ZnS quantum dots. The results suggested that the carbon dots were biocompatible, and their performance as fluorescence imaging agents was competitive. The implication to the use of carbon dots for in vitro and in vivo applications is discussed. PMID:20357893

  17. A prospective Phase II clinical trial of 5-aminolevulinic acid to assess the correlation of intraoperative fluorescence intensity and degree of histologic cellularity during resection of high-grade gliomas.

    PubMed

    Lau, Darryl; Hervey-Jumper, Shawn L; Chang, Susan; Molinaro, Annette M; McDermott, Michael W; Phillips, Joanna J; Berger, Mitchel S

    2016-05-01

    with cellularity Grade 3 ranged from 95% to 100% and 86% to 100%, respectively. In biopsies without tumor (cellularity Grade 0), 35.4% still demonstrated ALA fluorescence. Of those biopsies, 90.9% contained abnormal brain tissue, characterized by reactive astrocytes, scattered atypical cells, or inflammation, and 8.1% had normal brain. In nonfluorescent (ALA intensity 0) biopsies, 62.3% had tumor cells present. The ALA-associated complication rate among the study cohort was 3.4%. CONCLUSIONS The PPV of utilizing the most robust ALA fluorescence intensity (lava-like orange) as a predictor of tumor presence is high. However, the NPV of utilizing the absence of fluorescence as an indicator of no tumor is poor. ALA intensity is a strong predictor for degree of tumor cellularity for the most fluorescent areas but less so for lower ALA intensities. Even in the absence of tumor cells, reactive changes may lead to ALA fluorescence.

  18. High emotional reactivity toward an experimenter affects participation, but not performance, in cognitive tests with common marmosets (Callithrix jacchus).

    PubMed

    Schubiger, Michèle N; Wüstholz, Florian L; Wunder, André; Burkart, Judith M

    2015-05-01

    When testing primates with cognitive tasks, it is usually not considered that subjects differ markedly in terms of emotional reactivity toward the experimenter, which potentially affects a subject's cognitive performance. We addressed this issue in common marmosets (Callithrix jacchus), a monkey species in which males tend to show stronger emotional reactivity in testing situations, whereas females have been reported to outperform males in cognitive tasks. In a two-phase experiment, we first quantified the emotional reactivity of 14 subjects toward four different experimenters performing a standardized behavioral action sequence and then assessed whether and how it affected the subjects' participation and performance in a subsequent object permanence task. A test session was terminated if a subject refused to make a choice in four consecutive trials. Highly emotionally aroused individuals, particularly males, were less likely to participate in the cognitive task and completed fewer trials. However, whenever they did participate and were attentive to the task, their performance was not affected. Our results suggest that differences in emotional reactivity toward an experimenter have no major impact on cognitive performance if strict criteria are applied on when to abandon a test session and if performance is corrected for attention to the test procedure. Furthermore, they suggest that the reported sex differences in cognitive performance in marmosets may be owing to motivational and attentional factors, rather than a difference in cognitive ability per se.

  19. High-resolution fluorescence mapping of impurities in historical zinc oxide pigments: hard X-ray nanoprobe applications to the paints of Pablo Picasso

    NASA Astrophysics Data System (ADS)

    Casadio, Francesca; Rose, Volker

    2013-04-01

    Here for the first time we describe the use of high resolution nanoprobe X-ray fluorescence (XRF) mapping for the analysis of artists' paints, hierarchically complex materials typically composed of binder, pigments, fillers, and other additives. The work undertaken at the nanoprobe sought to obtain highly spatially resolved, highly sensitive mapping of metal impurities (Pb, Cd, Fe, and other metals) in submicron particles of zinc oxide pigments used in early 20th century artists' tube paints and enamel paints, with particular emphasis on Ripolin, a popular brand of French house paint used extensively by Pablo Picasso and some of his contemporaries. Analysis revealed that the Zn oxide particles only contain a little Fe, proving that the highest quality Zn oxide pigment, free of Pb and Cd, was used for Ripolin house paints as well as artists' paints. Nanoprobe XRF mapping also demonstrated that artists' tube paints generally have more abundant fillers and additional whites (based on Pb, Ti, Ca) than Ripolin paints, which contain mostly pure zinc oxide. The chemical characterization of paints at the nanoscale opens the path to a better understanding of their fabrication and chemical reactivity.

  20. Fluorescent Probe Encapsulated in SNAP-Tag Protein Cavity To Eliminate Nonspecific Fluorescence and Increase Detection Sensitivity.

    PubMed

    Zeng, Yan-Syun; Gao, Ruo-Cing; Wu, Ting-Wei; Cho, Chien; Tan, Kui-Thong

    2016-08-17

    Despite the promising improvements made recently on fluorescence probes for the detection of enzymes and reactive small molecules, two fundamental problems remain: weaker fluorescence of many dyes in aqueous buffers and strong nonspecific signals in samples containing high protein levels. In this paper, we introduce a novel fluorescent probe encapsulated in protein cavity (FPEPC) concept as demonstrated by SNAP-tag protein and three environment-sensitive fluorescence probes to overcome these two problems. The probes were constructed by following the current probe design for enzymes and reactive small molecules but with an additional benzylguanine moiety for selective SNAP-tag conjugation. The SNAP-tag conjugated probes achieved quantitative nitroreductase and hydrogen sulfide detection in blood plasma, whereas analyte concentrations were overestimated up to 700-fold when bare fluorescent probes were employed for detection. Furthermore, detection sensitivity was increased dramatically, as our probes displayed 390-fold fluorescence enhancement upon SNAP-tag conjugation, in stark contrast to the weak fluorescence of the free probes in aqueous solutions. Compared with the conventional approaches where fluorescent probes are encapsulated into polymers and nanoparticles, our simple and general approach successfully overcame many key issues such as dye leakage, long preparation steps, inconsistent dye-host ratios, difficulty in constructing in situ in a complex medium, and limited application to detect only small metabolites.