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

    PubMed

    Avonto, Cristina; Chittiboyina, Amar G; Rua, Diego; Khan, Ikhlas A

    2015-12-01

    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 replace conventional animal tests. Chemical methods are intended to characterize the potential of a sensitizer to induce earlier molecular initiating events. The presence of an electrophilic mechanistic domain is considered one of the essential chemical features to covalently bind to the biological target and induce further haptenation processes. Current in chemico assays rely on the quantification of unreacted model nucleophiles after incubation with the candidate sensitizer. In the current study, a new fluorescence-based method, 'HTS-DCYA assay', is proposed. The assay aims at the identification of reactive electrophiles based on their chemical reactivity toward a model fluorescent thiol. The reaction workflow enabled the development of a High Throughput Screening (HTS) method to directly quantify the reaction adducts. The reaction conditions have been optimized to minimize solubility issues, oxidative side reactions and increase the throughput of the assay while minimizing the reaction time, which are common issues with existing methods. Thirty-six chemicals previously classified with LLNA, DPRA or KeratinoSens™ were tested as a proof of concept. Preliminary results gave an estimated 82% accuracy, 78% sensitivity, 90% specificity, comparable to other in chemico methods such as Cys-DPRA. In addition to validated chemicals, six natural products were analyzed and a prediction of their sensitization potential is presented for the first time. PMID:26455772

  3. Determination of intracellular reactive oxygen species and high mitochondrial membrane potential in Percoll-treated viable boar sperm using fluorescence-activated flow cytometry.

    PubMed

    Guthrie, H D; Welch, G R

    2006-08-01

    The use of frozen semen in the swine industry is limited by problems with viability and fertility compared with liquid semen. Part of the reduction in sperm motility and fertility associated with cryopreservation may be due to oxidative damage from excessive or inappropriate formation of reactive oxygen species (ROS). Chemiluminescence measurements of ROS are not possible in live cells and are problematic because of poor specificity. An alternative approach, flow cytometry, was developed to identify viable boar sperm containing ROS utilizing the dyes hydroethidine and 2', 7'-dichlorodihydrofluorescein diacetate as oxidizable substrates and impermeant DNA dyes to exclude dead sperm. The percentage of sperm with high mitochondrial transmembrane potential was determined by flow cytometry using the mitochondrial probe 5, 5', 6, 6'-tetrachloro-1, 1', 3, 3'-tetraethylbenzimidazolylcarbocyanine iodide with propidium iodide staining to exclude nonviable cells. Sperm were incubated with and without ROS generators and free radical scavengers. Basal ROS formation was low (less than 4%) and did not differ (P = 0.26) between viable fresh and frozen-thawed boar sperm. In addition, fresh and frozen-thawed viable sperm were equally susceptible (P = 0.20) to intracellular formation of ROS produced by xanthine/xanthine oxidase (94.4 and 87.9% of sperm, respectively). Menadione increased (P < 0.05) ROS formation, decreased (P < 0.05) JC-1-aggregate fluorescence intensity, and decreased (P < 0.05) motion variables by 25 to 60%. The mechanism of inhibition of motility by ROS formation may be related to a decrease in mitochondrial charge potential below a critical threshold. Catalase and superoxide dismutase treatment in the presence of xanthine/xanthine oxidase indicated that hydrogen peroxide was the primary intracellular ROS measured. Further, catalase, but not superoxide dismutase, was capable of attenuating ROS-induced inhibition of motility. Whereas basal intracellular hydrogen

  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. 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.

  7. Highly thermostable fluorescent proteins

    DOEpatents

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

    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.

  8. Highly thermostable fluorescent proteins

    DOEpatents

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

    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.

  9. High-Pressure Fluorescence Spectroscopy.

    PubMed

    Maeno, Akihiro; Akasaka, Kazuyuki

    2015-01-01

    The combination of fluorescence and pressure perturbation is a widely used technique to study the effect of pressure on a protein system to obtain thermodynamic, structural and kinetic information on proteins. However, we often encounter the situation where the available pressure range up to 400 MPa of most commercial high-pressure fluorescence spectrometers is insufficient for studying highly pressure-stable proteins like inhibitors and allergenic proteins. To overcome the difficulty, we have recently developed a new high-pressure fluorescence system that allows fluorescence measurements up to 700 MPa. Here we describe the basic design of the apparatus and its application to study structural and thermodynamic properties of a couple of highly stable allergenic proteins, hen lysozyme and ovomucoid, using Tryptophan and Tyrosine/Tyrosinate fluorescence, respectively. Finally, we discuss the utility and the limitation of Trp and Tyr fluorescence. We discuss pitfalls of fluorescence technique and importance of simultaneous use of other high-pressure spectroscopy, particularly high-pressure NMR spectroscopy. PMID:26174405

  10. 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.

  11. 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.

  12. 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.

  13. Enantioselective fluorescent recognition in the fluorous phase: enhanced reactivity and expanded chiral recognition.

    PubMed

    Wang, Chao; Wu, Elaine; Wu, Xuedan; Xu, Xiangchuan; Zhang, Guoqing; Pu, Lin

    2015-03-25

    A novel perfluoroalkyl-BINOL-based chiral diketone is found to be the first highly enantioselective fluorescent sensor in the fluorous phase. One enantiomer of a chiral amino alcohol or diamine at a concentration greater than 1 mM can cause an up to 1200-2000-fold fluorescent enhancement of the sensor (0.08 mM), while the other enantiomer gives only a 10-50-fold enhancement. The fluorous-phase-based sensor is found to enhance the reactivity of the previously reported fluorous insoluble sensor with amino alcohols and expand its chiral recognition ability. Dynamic light scattering studies show the formation of aggregates of very different particle sizes when two enantiomers of a substrate interact with the sensor in perfluorohexane (FC-12). This substantial difference enables easy discrimination of the enantiomers with UV-lamps or even the naked eye. NMR, IR, and mass spectroscopic studies indicate that the fluorescent enhancement and enantioselectivity should originate from the fluorous solvent-promoted nucleophilic addition of the amino alcohols to the carbonyl groups of the sensor. PMID:25761050

  14. 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

  15. 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.

  16. Fluorescent Approaches to High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Forsythe, Elizabeth; Achari, Aniruddha

    2006-01-01

    We have shown that by covalently modifying a subpopulation, less than or equal to 1%, of a macromolecule with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification, and the presence of the probe at low concentrations does not affect the X-ray data quality or the crystallization behavior. The presence of the trace fluorescent label gives a number of advantages when used with high throughput crystallizations. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination crystals show up as bright objects against a dark background. Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Brightly fluorescent crystals are readily found against less bright precipitated phases, which under white light illumination may obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries as the protein or protein structures is all that shows up. Fluorescence intensity is a faster search parameter, whether visually or by automated methods, than looking for crystalline features. We are now testing the use of high fluorescence intensity regions, in the absence of clear crystalline features or "hits", as a means for determining potential lead conditions. A working hypothesis is that kinetics leading to non-structured phases may overwhelm and trap more slowly formed ordered assemblies, which subsequently show up as regions of brighter fluorescence intensity. Preliminary experiments with test proteins have resulted in the extraction of a number of crystallization conditions from screening outcomes based solely on the presence of bright fluorescent regions. Subsequent experiments will test this approach using a wider

  17. On reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  18. Coupling Electrochemistry with Fluorescence Confocal Microscopy To Investigate Electrochemical Reactivity: A Case Study with the Resazurin-Resorufin Fluorogenic Couple.

    PubMed

    Doneux, Thomas; Bouffier, Laurent; Goudeau, Bertrand; Arbault, Stéphane

    2016-06-21

    The redox couple resazurin-resorufin exhibits electrofluorochromic properties which are investigated herein by absorption and fluorescence spectroelectrochemistry and by electrochemically coupled-fluorescence confocal laser scanning microscopy (EC-CLSM). At pH 10, the highly fluorescent resorufin dye is generated at the electrode surface by the electrochemical reduction of the poorly fluorescent resazurin. Performing EC-CLSM at electrode surfaces allows to monitor spatially resolved electrochemical processes in situ and in real time. Using a small (315 μm diameter) cylindrical electrode, a steady-state diffusion layer builds up under potentiostatic conditions at -0.45 V vs Ag|AgCl. Mapping the fluorescence intensity in 3D by CLSM enables us to reconstruct the relative concentration profile of resorufin around the electrode. The comparison of the experimental diffusion-profile with theoretical predictions demonstrates that spontaneous convection has a direct influence on the actual thickness of the diffusion layer, which is smaller than the value predicted for a purely diffusional transport. This study shows that combining fluorescence CLSM with electrochemistry is a powerful tool to study electrochemical reactivity at a spatially resolved level. PMID:27247989

  19. HIGH REACTIVITY SORBENTS FOR SO2 CONTROL

    EPA Science Inventory

    The paper discusses studies, relating to air pollution control from coal-fired utility boilers, that show that the primary variable affecting sorbent reactivity at high temperature or at low temperature with water droplets is surface area. For the development of high surface area...

  20. 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.

  1. Hg2+-reactive double hydrophilic block copolymer assemblies as novel multifunctional fluorescent probes with improved performance.

    PubMed

    Hu, Jinming; Li, Changhua; Liu, Shiyong

    2010-01-19

    We report on novel type of responsive double hydrophilic block copolymer (DHBC)-based multifunctional chemosensors to Hg(2+) ions, pH, and temperatures and investigate the effects of thermo-induced micellization on the detection sensitivity. Well-defined DHBCs bearing rhodamine B-based Hg(2+)-reactive moieties (RhBHA) in the thermo-responsive block, poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-RhBHA) (PEO-b-P(NIPAM-co-RhBHA)), were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Nonfluorescent RhBHA moieties are subjected to selective ring-opening reaction upon addition of Hg(2+) ions or lowering solution pH, producing highly fluorescent acyclic species. Thus, at room temperature PEO-b-P(NIPAM-co-RhBHA) DHBCs can serve as water-soluble multifunctional and efficient fluorescent chemosensors to Hg(2+) ions and pH. Upon heating above the lower critical solution temperature (approximately 36 degrees C) of the PNIPAM block, they self-assemble into micelles possessing P(NIPAM-co-RhBHA) cores and well-solvated PEO coronas, which were fully characterized by dynamic and static laser light scattering. It was found that the detection sensitivity to Hg(2+) ions and pH could be dramatically improved at elevated temperatures due to fluorescence enhancement of RhBHA residues in the acyclic form, which were embedded within hydrophobic cores of thermo-induced micellar aggregates. This work represents a proof-of-concept example of responsive DHBC-based multifunctional fluorescent chemosensors for the highly efficient detection of Hg(2+) ions, pH, and temperatures with tunable detection sensitivity. Compared to reaction-based small molecule Hg(2+) probes in previous literature reports, the integration of stimuli-responsive block copolymers with well-developed small molecule-based selective sensing moieties in the current study are expected to exhibit preferred advantages including enhanced detection sensitivity, water dispersibility

  2. 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)

  3. 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.

  4. 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

  5. A fluorescent immunoassay for the determination of procalcitonin and C-reactive protein

    NASA Astrophysics Data System (ADS)

    Baldini, F.; Bolzoni, L.; Giannetti, A.; Porro, G.; Senesi, F.; Trono, C.

    2009-05-01

    The discrimination of viral and bacterial sepsis is an important issue in intensive care patients. For this purpose, the simultaneous measurements of different analytes such as C-reactive protein (CRP), procalcitonin (PCT), myeloperoxidase, interleukines and neopterin, are necessary. A novel optical platform was designed and realised for the implementation of fluorescence-based immunoassays. The core of the optical platform is a plastic biochip, formed by a series of microchannels each of them devoted to the determination of a single analyte. Sandwich assays for CRP and PCT spiked in serum were performed in order to demonstrate the reliability of a multi-array device.

  6. 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

  7. High-order fluorescence fluctuation analysis of model protein clusters.

    PubMed Central

    Palmer, A G; Thompson, N L

    1989-01-01

    The technique of high-order fluorescence fluctuation autocorrelation for detecting and characterizing protein oligomers was applied to solutions containing two fluorescent proteins in which the more fluorescent proteins were analogues for clusters of the less fluorescent ones. The results show that the model protein clusters can be detected for average numbers of observed subunits (free monomers plus monomers in oligomers) equal to 10-100 and for relative fluorescent yields that correspond to oligomers as small as trimers. High-order fluorescent fluctuation analysis may therefore be applicable to cell surface receptor clusters in natural or model membranes. PMID:2548201

  8. Vertical nanopillars for highly localized fluorescence imaging

    PubMed Central

    Xie, Chong; Hanson, Lindsey; Cui, Yi; Cui, Bianxiao

    2011-01-01

    Observing individual molecules in a complex environment by fluorescence microscopy is becoming increasingly important in biological and medical research, for which critical reduction of observation volume is required. Here, we demonstrate the use of vertically aligned silicon dioxide nanopillars to achieve below-the-diffraction-limit observation volume in vitro and inside live cells. With a diameter much smaller than the wavelength of visible light, a transparent silicon dioxide nanopillar embedded in a nontransparent substrate restricts the propagation of light and affords evanescence wave excitation along its vertical surface. This effect creates highly confined illumination volume that selectively excites fluorescence molecules in the vicinity of the nanopillar. We show that this nanopillar illumination can be used for in vitro single-molecule detection at high fluorophore concentrations. In addition, we demonstrate that vertical nanopillars interface tightly with live cells and function as highly localized light sources inside the cell. Furthermore, specific chemical modification of the nanopillar surface makes it possible to locally recruit proteins of interest and simultaneously observe their behavior within the complex, crowded environment of the cell. PMID:21368157

  9. 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

  10. 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

  11. Novel Nanophosphors for High Efficiency Fluorescent Lamps

    SciTech Connect

    Alok M. Srivastava

    2005-09-30

    This is the Yearly 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 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. The prime technical approach is the development of NCP quantum-splitting phosphor (QSP) and ultra-violet emitting phosphors with quantum efficiencies exceeding that of the conventional phosphors at 185 nm. Our chief achievement, during the current contract period, pertains to the successful synthesis and characterization of coated phosphors. We demonstrated several synthesis techniques for the coating of micron sized commercial phosphors with quantum-splitting and UV emitting nanophosphors. We have also continued our fundamental investigations into the physical processes that determine the quantum efficiency of the nanophosphors and this has further helped codify a set of rules for the host lattice that support efficient quantum splitting and UV emission at room temperature. In this report we summarize the technical work completed under the Program, summarize our findings about the performance limits of the various technologies we investigated, and outline promising paths for future work.

  12. Novel high-sensitivity fluorescence polarization reader

    NASA Astrophysics Data System (ADS)

    Hoyt, Clifford C.; Levenson, Richard M.; Banks, Peter

    2001-05-01

    We have developed a new fluorescence polarization (FP) reader suitable for high-throughput screening (HST) and ultra-HTS whose assay-performance and sample-throughput are both considerably improved over present state-of-the-art instrumentation. The SymmetryTM reader possesses a number of features that differ from conventional HTS FP readers. These include: laser-based excitation, liquid crystal polarization optics that rapidly and accurately measure polarization states; and CCD detectors to capture emission from multiple wells. We show that the performance in assays relevant to the drug discovery process, such as G- protein coupled receptor-based assays, is significantly enhanced due to a dramatic improvement in precision. Furthermore, the CCD-detection system used can substantially improve sample throughput compared to sequential readers while maintaining high performance.

  13. 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. PMID:25127598

  14. 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)

  15. 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. PMID:25761204

  16. Monitoring Cr Intermediates and Reactive Oxygen Species with Fluorescent Probes during Chromate Reduction

    PubMed Central

    2015-01-01

    Cr(VI) genotoxicity is caused by products of its reductive metabolism inside the cells. Reactive oxygen species (ROS) and Cr(V,IV) intermediates are potential sources of oxidative damage by Cr(VI). Here, we investigated seven fluorescent probes for the detection of ROS and non-ROS oxidants in Cr(VI) reactions with its main reducers. We found that Cr(V)-skipping metabolism of Cr(VI) by ascorbate in vitro gave no responses with all tested dyes, indicating nonreactivity of Cr(IV) and absence of ROS. Cr(VI) reduction with glutathione (GSH) or Cys strongly enhanced the fluorescence of dichlorofluorescein (DCF) and dihydrorhodamine 123 (DHR123) but produced minimal fluorescence with dihydroethidium and no increases with aminophenylfluorescein and CellRox Green, Orange, and Red. Several tests showed that Cr(VI)-thiol reactions lacked ROS and that Cr(V) caused oxidation of DCF and DHR123. DCF reacted only with free Cr(V), whereas DHR123 detected both the free Cr(V) and Cr(V)-GSH complex. We estimated that Cr(VI)-GSH reactions generated approximately 75% Cr(V)-GSH and 25% free Cr(V), whereas Cys reactions appeared to produce only free Cr(V). DHR123 measurements in H460 cells showed that reduction of Cr(VI) was complete within 20 min postexposure, but it lasted at least 1 h without GSH. Cells with restored ascorbate levels exhibited no DCF or DHR123 oxidation by Cr(VI). Overall, our results demonstrated that Cr(VI) metabolism with its biological reducers lacked ROS and that DHR123 and DCF responses were indicators of total and free Cr(V), respectively. CellRox dyes, dihydroethidium and aminophenylfluorescein, are insensitive to Cr(V,IV) and can be used for monitoring ROS during coexposure to Cr(VI) and oxidants. PMID:24646070

  17. 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...

  18. High frame rate fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Agronskaia, A. V.; Tertoolen, L.; Gerritsen, H. C.

    2003-07-01

    A fast time-domain based fluorescence lifetime imaging (FLIM) microscope is presented that can operate at frame rates of hundreds of frames per second. A beam splitter in the detection path of a wide-field fluorescence microscope divides the fluorescence in two parts. One part is optically delayed with respect to the other. Both parts are viewed with a single time-gated intensified CCD camera with a gate width of 5 ns. The fluorescence lifetime image is obtained from the ratio of these two images. The fluorescence lifetime resolution of the FLIM microscope is verified both with dye solutions and fluorescent latex beads. The fluorescence lifetimes obtained from the reference specimens are in good agreement with values obtained from time correlated single photon counting measurements on the same specimens. The acquisition speed of the FLIM system is evaluated with a measurement of the calcium fluxes in neonatal rat myocytes stained with the calcium probe Oregon Green 488-Bapta. Fluorescence lifetime images of the calcium fluxes related to the beating of the myocytes are acquired with frame rates of up to 100 Hz.

  19. Riboflavin enhanced fluorescence of highly reduced graphene oxide

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  20. 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.

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

    PubMed

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

    2004-05-18

    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 beta-secretase. PMID:15136731

  2. 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.

  3. Fluorescent Approaches to High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Forsythe, Elizabeth; Achari, Amiruddha

    2005-01-01

    X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1 %, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "hits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low

  4. Fluorescent Approaches to High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Forsythe, Elizabeth

    2005-01-01

    X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, 51%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear hits. Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low cost optics

  5. Fluorescent Approaches to High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Minamitani, Elizabeth Forsythe; Pusey, Marc L.

    2004-01-01

    X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically cannot reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of a macromolecules purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals will show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "bits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment

  6. Fluorescent Approaches to High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Forsythe, Elizabeth

    2004-01-01

    X-ray crystallography remains the primary method for determining the structure of macromolecules. The first requirement is to have crystals, and obtaining them is often the rate-limiting step. The numbers of crystallization trials that are set up for any one protein for structural genomics, and the rate at which they are being set up, now overwhelm the ability for strictly human analysis of the results. Automated analysis methods are now being implemented with varying degrees of success, but these typically can not reliably extract intermediate results. By covalently modifying a subpopulation, less than or = 1%, of a macromolecule solution with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination the crystals show up as bright objects against a dark background. As crystalline packing is more dense than amorphous precipitate, the fluorescence intensity can be used as a guide in distinguishing different types of precipitated phases, even in the absence of obvious crystalline features, widening the available potential lead conditions in the absence of clear "hits." Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Also, brightly fluorescent crystals are readily found against less fluorescent precipitated phases, which under white light illumination may serve to obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries and by having the protein or protein structures all that show up. The trace fluorescently labeled crystals will also emit with sufficient intensity to aid in the automation of crystal alignment using relatively low

  7. 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.

  8. Highly reactive light-dependent monoterpenes in the Amazon

    SciTech Connect

    Jardine, A. B.; Jardine, K. J.; Fuentes, J. D.; Martin, S. T.; Martins, G.; Durgante, F.; Carneiro, V.; Higuchi, N.; Manzi, A. O.; Chambers, J. Q.

    2015-03-06

    Despite orders of magnitude difference in atmospheric reactivity and great diversity in biological functioning, little is known about monoterpene speciation in tropical forests. Here we report vertically resolved ambient air mixing ratios for 12 monoterpenes in a central Amazon rainforest including observations of the highly reactive cis-β-ocimene (160 ppt), trans-β-ocimene (79 ppt), and terpinolene (32 ppt) which accounted for an estimated 21% of total monoterpene composition yet 55% of the upper canopy monoterpene ozonolysis rate. All 12 monoterpenes showed a mixing ratio peak in the upper canopy, with three demonstrating subcanopy peaks in 7 of 11 profiles. Leaf level emissions of highly reactive monoterpenes accounted for up to 1.9% of photosynthesis confirming light-dependent emissions across several Amazon tree genera. These results suggest that highly reactive monoterpenes play important antioxidant roles during photosynthesis in plants and serve as near-canopy sources of secondary organic aerosol precursors through atmospheric photooxidation via ozonolysis.

  9. Highly reactive light-dependent monoterpenes in the Amazon

    NASA Astrophysics Data System (ADS)

    Jardine, A. B.; Jardine, K. J.; Fuentes, J. D.; Martin, S. T.; Martins, G.; Durgante, F.; Carneiro, V.; Higuchi, N.; Manzi, A. O.; Chambers, J. Q.

    2015-03-01

    Despite orders of magnitude difference in atmospheric reactivity and great diversity in biological functioning, little is known about monoterpene speciation in tropical forests. Here we report vertically resolved ambient air mixing ratios for 12 monoterpenes in a central Amazon rainforest including observations of the highly reactive cis-β-ocimene (160 ppt), trans-β-ocimene (79 ppt), and terpinolene (32 ppt) which accounted for an estimated 21% of total monoterpene composition yet 55% of the upper canopy monoterpene ozonolysis rate. All 12 monoterpenes showed a mixing ratio peak in the upper canopy, with three demonstrating subcanopy peaks in 7 of 11 profiles. Leaf level emissions of highly reactive monoterpenes accounted for up to 1.9% of photosynthesis confirming light-dependent emissions across several Amazon tree genera. These results suggest that highly reactive monoterpenes play important antioxidant roles during photosynthesis in plants and serve as near-canopy sources of secondary organic aerosol precursors through atmospheric photooxidation via ozonolysis.

  10. Highly Fluorescent dye-nanoclay Hybrid Materials Made from Different Dye Classes.

    PubMed

    Grabolle, Markus; Starke, Marian; Resch-Genger, Ute

    2016-04-12

    Nanoclays like laponites, which are commercially avaible in large quantities for a very moderate price, provide a facile solubilization strategy for hydrophobic dyes without the need for chemical functionalization and can act as a carrier for a high number of dye molecules. This does not require reactive dyes, amplifies fluorescence signals from individual emitters due to the high number of dyes molecules per laponite disk, and renders hydrophobic emitters applicable in aqueous environments. Aiming at the rational design of bright dye-loaded nanoclays as a new class of fluorescent reporters for bioanalysis and material sciences and the identification of dye structure-property relationships, we screened a series of commercial fluorescent dyes, differing in dye class, charge, and character of the optical transitions involved, and studied the changes of their optical properties caused by clay adsorption at different dye loading concentrations. Upon the basis of our dye loading density-dependent absorption and fluorescence measurements with S2105 and Lumogen F Yellow 083, we could identify two promising dye-nanoclay hybrid materials that reveal high fluorescence quantum yields of the nanoclay-adsorbed dyes of at least 0.20 and low dye self-quenching even at high dye-loading densities of up to 50 dye molecules per laponite platelet. PMID:27007448

  11. High missing OH reactivity in summertime boreal forest environment

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Williams, J.; Sinha, V.; Song, W.; Johnson, A.; Yassaa, N.; Phillips, G.; Crowley, J.; Axinte, R.; Fischer, H.; Gonzales, D.; Valverde-Canossa, J.; Vogel, A.; Hoffmann, T.; Rantala, P.; Rinne, J.; Kulmala, M.; Ouwersloot, H.; Vila, J.; Lelieveld, J.

    2012-04-01

    Forest emissions represent a strong potential sink for the main tropospheric oxidant, the hydroxyl radical (OH). Resulting photochemical products can influence ambient ozone, contribute to particle formation and growth processes, and therefore impact climate and air quality. Direct measurements of total OH reactivity in ambient air can reveal gaps in the general understanding of reactive gaseous emissions from the biosphere to the atmosphere. By comparing the contribution from individually measured compounds to the overall OH sink and the directly measured total OH reactivity, the size of any unaccounted for, or "missing" sink can be deduced. In July and August 2010 an intensive field measurement campaign (HUMPPA-COPEC 2010) was performed at the Finnish boreal forest station SMEAR II in Hyytiälä (Latitude 61° 51' N; Longitude 24° 17' E) to investigate the summertime emissions and photochemistry of volatile organic compounds (VOCs) [1]. Speciated VOCs, the key oxidants OH, O3 and NO3, as well as aerosol, ions and other trace gases were quantified. Total OH reactivity was measured directly using the Comparative Reactivity Method (CRM) [2]. This total OH reactivity method is an in-situ determination of the total loss rate of OH radicals caused by all reactive species in ambient air. During HUMPPA-COPEC 2010, total OH reactivity was monitored both inside and directly above the canopy. The impact of various parameters such as temperature and light dependent biogenic emissions and reaction products in "normal" and "stressed" conditions, the long-range transport of pollution and the boundary layer height development were characterized. For "normal" boreal conditions a missing reactivity of 58% was determined, whereas for "stressed" boreal conditions this increased to 89 %. Possible explanations are proposed to explain the high missing OH reactivity in summertime boreal forest environment. [1] J. Williams et al, 2011, Atmos. Chem. Phys., 11, 10599-10618 [2] V. Sinha et

  12. 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

  13. 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

  14. Optical spectroscopy of a highly fluorescent aggregate of bacteriochlorophyll c

    NASA Technical Reports Server (NTRS)

    Causgrove, T. P.; Cheng, P.; Brune, D. C.; Blankenship, R. E.

    1993-01-01

    Bacteriochlorophyll (BChl) c and a similar model compound, Mg-methyl bacteriopheophorbide d, form several types of aggregates in nonpolar solvents. One of these aggregates is highly fluorescent, with a quantum yield higher than that of the monomer. This aggregate is also unusual in that it shows a rise time in its fluorescence emission decay at certain wavelengths, which is ascribed to a change in conformation of the aggregate. An analysis of fluorescence depolarization data is consistent with either a linear aggregate of four or five monomers or preferably a cyclic arrangement of three dimers.

  15. Highly fluorescent semiconducting pyrazoline materials for optoelectronics

    NASA Astrophysics Data System (ADS)

    Ramkumar, V.; Kannan, P.

    2015-08-01

    An investigation has been made to synthesize small organic materials possessing longer wavelength emission in a simple manner. Three novel pyrazoline compounds were synthesized and characterized by appropriate approaches. The effect of thiophene, furan and pyridine substitution on pyrazoline skeleton was studied and explained systematically. Green, blue and violet emission was obtained with respect to different substituent groups. The fluorescence decay time and quantum yield of the synthesized materials I, II and III are found to be 3.42, 2.65, 2.83 ns and 0.83, 0.76, 0.78 respectively. The theoretical quantum calculation was used to optimize the spatial distribution of ground state geometry (HOMO) and excited state geometry (LUMO) levels of the molecules. The materials performance and bandgap energies (Eg) of all the three compounds revealed that they belong to a semiconductor materials category.

  16. A BODIPY-based fluorescent probe for ratiometric detection of gold ions: utilization of Z-enynol as the reactive unit.

    PubMed

    Üçüncü, Muhammed; Karakuş, Erman; Emrullahoğlu, Mustafa

    2016-07-01

    Using an irreversible intramolecular cyclisation pathway triggered by gold ions, a boron-dipyrromethene (BODIPY) based fluorescent probe integrated with a reactive Z-enynol motif responds selectively to gold ions. With the addition of gold(iii), the probe displays ratiometric fluorescence behaviour clearly observable to the naked eye under both visible and UV light. PMID:27284598

  17. Frequency Division Multiplexed Multichannel High-Speed Fluorescence Confocal Microscope

    PubMed Central

    Wu, Fei; Zhang, Xueqian; Cheung, Joseph Y.; Shi, Kebin; Liu, Zhiwen; Luo, Claire; Yin, Stuart; Ruffin, Paul

    2006-01-01

    In this article, we report a new type of fluorescence confocal microscope: frequency division multiplexed multichannel fluorescence confocal microscope, in which we encode the spatial location information into the frequency domain. In this microscope, the exciting laser beam is first split into multiple beams and each beam is modulated at a different frequency. These multiple beams are focused at different locations of the target to form multiple focal points, which further generate multiple fluorescent emission spots. The fluorescent emissions from different focal points are also modulated at different frequencies, because the exciting beams are modulated at different frequencies (or difference carrier frequency). Then, all the fluorescent emissions (modulated at different frequencies) are collected together and detected by a highly sensitive, large-dynamic-range photomultiplier tube. By demodulating the detected signal (i.e., via the Fourier transform), we can distinguish the fluorescent light emitted from the different locations by the corresponding carrier frequencies. The major advantage of this unique fluorescence confocal microscope is that it not only has a high sensitivity because of the use of photomultiplier tube but also can get multiple-point data simultaneously, which is crucial to study the dynamic behavior of many biological process. As an initial step, to verify the feasibility of the proposed multichannel confocal microscope, we have developed a two-channel confocal fluorescence microscope and applied it to study the dynamic behavior of the changes of the calcium ion concentration during the single cardiac myocyte contraction. Our preliminary experimental results demonstrated that we could indeed realize multichannel confocal fluorescence microscopy by utilizing the frequency division multiplexed microscope, which could become an effective tool to study the dynamic behavior of many biological processes. PMID:16815894

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

    PubMed

    Guthrie, H David; Welch, Glenn R

    2010-01-01

    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-diaza-s-indacene-3-undecanoic acid, C(11)BODIPY(581/591) (BODIPY). ROS was detected by red fluorescence emission from oxidization of HE and membrane lipid peroxidation was detected by green fluorescence emission from oxidation of BODIPY in individual live sperm. Of the reactive oxygen species generators tested, BODIPY oxidation was specific for FeSo4/ascorbate (FeAc), because menadione and H(2)O(2) had little or no effect. The oxidization of hydroethidine to ethidium was specific for menadione and H(2)O(2); FeAc had no effect. The incidence of basal or spontaneous ROS formation and membrane lipid peroxidation were low in boar sperm (<1% of live sperm) in fresh semen or after low temperature storage; however the sperm were quite susceptible to treatment-induced ROS formation and membrane lipid peroxidation. PMID:20072917

  19. 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.

  20. Optically modulated fluorescence bioimaging: visualizing obscured fluorophores in high background.

    PubMed

    Hsiang, Jung-Cheng; Jablonski, Amy E; Dickson, Robert M

    2014-05-20

    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 brightness is

  1. Real-Time Discrimination and Versatile Profiling of Spontaneous Reactive Oxygen Species in Living Organisms with a Single Fluorescent Probe.

    PubMed

    Zhang, Ruilong; Zhao, Jun; Han, Guangmei; Liu, Zhengjie; Liu, Cui; Zhang, Cheng; Liu, Bianhua; Jiang, Changlong; Liu, Renyong; Zhao, Tingting; Han, Ming-Yong; Zhang, Zhongping

    2016-03-23

    Fluorescent probes are powerful tools for the investigations of reactive oxygen species (ROS) in living organisms by visualization and imaging. However, the multiparallel assays of several ROS with multiple probes are often limited by the available number of spectrally nonoverlapping chromophores together with large invasive effects and discrepant biological locations. Meanwhile, the spontaneous ROS profilings in various living organs/tissues are also limited by the penetration capability of probes across different biological barriers and the stability in reactive in vivo environments. Here, we report a single fluorescent probe to achieve the effective discrimination and profiling of hydroxyl radicals (•OH) and hypochlorous acid (HClO) in living organisms. The probe is constructed by chemically grafting an additional five-membered heterocyclic ring and a lateral triethylene glycol chain to a fluorescein mother, which does not only turn off the fluorescence of fluorescein, but also create the dual reactive sites to ROS and the penetration capability in passing through various biological barriers. The reactions of probe with •OH and HClO simultaneously result in cyan and green emissions, respectively, providing the real-time discrimination and quantitative analysis of the two ROS in cellular mitochondria. Surprisingly, the accumulation of probes in the intestine and liver of a normal-state zebrafish and the transfer pathway from intestine-to-blood-to-organ/tissue-to-kidney-to-excretion clearly present the profiling of spontaneous •OH and HClO in these metabolic organs. In particular, the stress generation of •OH at the fresh wound of zebrafish is successfully visualized for the first time, in spite of its extremely short lifetime. PMID:26938117

  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. Laser-induced fluorescence monitoring of the gas phase in a glow discharge during reactive sputtering of vanadium

    NASA Astrophysics Data System (ADS)

    Khvostikov, V. A.; Grazhulene, S. S.; Burmii, Zh. P.; Marchenko, V. A.

    2011-11-01

    Processes in the gas phase of a glow discharge during diode and magnetron reactive sputtering of vanadium in an Ar-O2 atmosphere have been investigated by laser-induced fluorescence (LIF) as a function of the parameters of the glow discharge and the composition of the atmosphere. The intensity of the fluorescence spectra increased by 1.5-2.0 orders of magnitude in the magnetron sputtering process compared with that of diode sputtering. Under continuous sputtering conditions, the dependences of the intensities and relative compositions of the fluorescence spectra on the discharge parameters (discharge voltage and current) have been investigated. In pulsed mode of the glow discharge, the dynamics of changes in the spectra have been studied versus variations in the discharge duration and the lag time for recording the fluorescence signal. The dependence of the spectral line intensities on the partial pressure of oxygen has been found for vanadium and its oxide. The cathode surface at pressures of 0.03-0.04 Pa was shown to convert to the oxidized state.

  5. 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

  6. 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

  7. Investigating the Reactivities of a Polyketide Synthase Module through Fluorescent Click Chemistry

    PubMed Central

    Hughes, Amanda Jane; Tibby, Matthew R.; Wagner, Drew T.; Brantley, Johnathan N.; Keatinge-Clay, Adrian T.

    2014-01-01

    A method for monitoring in vitro polyketide synthesis has been developed whereby nonchromophoric polyketide products are made brightly fluorescent in a simple, rapid, inexpensive, and bioorthogonal manner through CuAAC with sulforhodamine B azide. PMID:24196586

  8. 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;…

  9. High-resolution methods for fluorescence retrieval from space.

    PubMed

    Mazzoni, Marina; Falorni, Pierluigi; Verhoef, Wouter

    2010-07-19

    The retrieval from space of a very weak fluorescence signal was studied in the O(2)A and O(2)B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of the atmosphere was simulated by means of a commercial radiative-transfer program at a high resolution (0.1 cm(-1)). A test data set was generated in order to simulate sun-induced chlorophyll fluorescence at the top of the canopy. Reflectance terms were spectrally modeled using cubic splines and fluorescence by means of the sum of two Voigt functions. Sensor radiance residual minimization was performed in the presence of a multiplicative noise, thus ensuring that the sensor simulations were realistic. The study, which focused on the possibility of retrieving fluorescence with an accuracy better than 10%, was performed for instrument resolutions ranging from about 0.4 cm(-1) to 2 cm(-1) in order to test the algorithm for the characteristics of existing and planned hyper-spectral sensors. The algorithm was also used to retrieve fluorescence in the single O(2)A band at the OCO and TANSO-FTS instrument spectral resolutions. PMID:20720947

  10. High-Level Fluorescence Labeling of Gram-Positive Pathogens

    PubMed Central

    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. PMID:21731607

  11. Highly reactive light-dependent monoterpenes in the Amazon

    DOE PAGESBeta

    Jardine, A. B.; Jardine, K. J.; Fuentes, J. D.; Martin, S. T.; Martins, G.; Durgante, F.; Carneiro, V.; Higuchi, N.; Manzi, A. O.; Chambers, J. Q.

    2015-03-06

    Despite orders of magnitude difference in atmospheric reactivity and great diversity in biological functioning, little is known about monoterpene speciation in tropical forests. Here we report vertically resolved ambient air mixing ratios for 12 monoterpenes in a central Amazon rainforest including observations of the highly reactive cis-β-ocimene (160 ppt), trans-β-ocimene (79 ppt), and terpinolene (32 ppt) which accounted for an estimated 21% of total monoterpene composition yet 55% of the upper canopy monoterpene ozonolysis rate. All 12 monoterpenes showed a mixing ratio peak in the upper canopy, with three demonstrating subcanopy peaks in 7 of 11 profiles. Leaf level emissionsmore » of highly reactive monoterpenes accounted for up to 1.9% of photosynthesis confirming light-dependent emissions across several Amazon tree genera. These results suggest that highly reactive monoterpenes play important antioxidant roles during photosynthesis in plants and serve as near-canopy sources of secondary organic aerosol precursors through atmospheric photooxidation via ozonolysis.« less

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

    PubMed

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

    2015-08-01

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

  14. Fluorescent Mueller matrix analysis of a highly scattering turbid media

    SciTech Connect

    Satapathi, Soumitra; Soni, Jalpa; Ghosh, Nirmalya

    2014-03-31

    We report the fluorescent Mueller matrix analysis of a highly scattering, inhomogeneous, and low quantum yield polymeric nanoparticle system. Both the ground and the excited state anisotropy of this turbid system were measured. The excited state anisotropy was found to be higher than ground state anisotropy by inverse polar decomposition analysis. The depolarization coefficients of these polythiophene nanoparticles were experimentally determined by recording Mueller matrices from this complex random medium. This approach provides an alternative method of determining optical characteristics of low quantum efficiency turbid system like fluorescently leveled tissue phantom.

  15. Synthesis, functionalization and bioimaging applications of highly fluorescent carbonnanoparticles

    NASA Astrophysics Data System (ADS)

    Chandra, Sourov; Das, Pradip; Bag, Sourav; Laha, Dipranjan; Pramanik, Panchanan

    2011-04-01

    Highly fluorescent crystalline carbonnanoparticles (CNPs) have been synthesized by one step microwave irradiation of sucrose with phosphoric acid at 100 W for 3 min 40 s. This method is very simple, rapid and economical and hence can be used for large scale applications. The average particle sizes are 3 to 10 nm and they emit bright green fluorescence under the irradiation of UV-light. Therefore, the particles can be used as a unique material for bioimaging as well as drug delivery. To further increase the fluorescence property of the synthetic carbonnanoparticles we simply functionalized them by using different organic dyes, such as fluorescein, rhodamine B and α-naphthylamine the maximum fluorescence intensity was observed for the particles functionalized with fluorescein. It is very interesting to note that all of those compounds show maximum fluorescence intensity at 225 nm excitation wavelength and for any excitation wavelength the peak positions are exactly same the position as that of CNPs itself, which is completely different from the individual precursors (dyes). All of the above compounds, including CNPs, have also been successfully introduced into the erythrocyte enriched fraction of healthy human blood cells with minimum cytotoxicity.

  16. 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.

  17. Aqueous synthesis of near-infrared highly fluorescent platinum nanoclusters

    NASA Astrophysics Data System (ADS)

    García Fernández, Jenifer; Trapiella-Alfonso, Laura; Costa-Fernández, José M.; Pereiro, Rosario; Sanz-Medel, Alfredo

    2015-05-01

    A one-step synthesis of near infrared fluorescent platinum nanoclusters (PtNCs) in aqueous medium is described. The proposed optimized procedure for PtNC synthesis is rather simple, fast and it is based on the direct metal reduction with NaBH4. Bidentated thiol ligands (lipoic acid) were selected as nanoclusters stabilizers in water media. The structural characterization revealed attractive features of the PtNCs, including small size, high water solubility, near-infrared luminescence centered at 680 nm, long-term stability and the highest quantum yield in water reported so far (47%) for PtNCs. Moreover, their stability in different pH media and an ionic strength of 0.2 M NaCl was studied and no significant changes in fluorescence emission were detected. In brief, they offer a new type of fluorescent noble metal nanoprobe with a great potential to be applied in several fields, including biolabeling and imaging experiments.

  18. In situ measurement of reactive neutral constituents in the thermosphere by atomic and molecular resonance fluorescence

    NASA Technical Reports Server (NTRS)

    Anderson, J. G.

    1978-01-01

    The Tethered Satellite System in combination with in situ atomic and molecular resonance fluorescence techniques can treat the problem of simultaneously determining the absolute density of atomic and molecular species known to control the photochemical structure of the upper atmosphere. Two familities of reactants which can be treated by these techniques are the nitrogen oxygen family and the hydrogen oxygen family.

  19. 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

  20. Titanium dioxide nanoswords with highly reactive, photocatalytic facets

    NASA Astrophysics Data System (ADS)

    Sosnowchik, Brian D.; Chiamori, Heather C.; Ding, Yong; Ha, Jong-Yoon; Wang, Zhong Lin; Lin, Liwei

    2010-12-01

    Titanium dioxide (TiO2) is one of the most widely studied and important materials for catalysis, photovoltaics, and surface science applications, but the ability to consistently control the relative exposure of higher surface energy facets during synthesis remains challenging. Here, we present the repeatable synthesis of highly reactive, rutile {001} or {101} facets on broad, sword-shaped TiO2 nanostructures rapidly synthesized in minutes. Growth occurs along planes of lower surface energy, repeatedly yielding nanostructures with large, high energy facets. The quantitative photocatalytic reactivity of the nanoswords, demonstrated by the photoreduction of silver, is over an order of magnitude higher than reference low energy TiO2{110} substrates. Therefore, the higher surface energy dominated TiO2 nanoswords are ideal structures for characterizing the physicochemical properties of rutile TiO2, and may be used to enhance a variety of catalytic, optical, and clean-technology applications.

  1. 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...

  2. 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…

  3. 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.

  4. Quantitative high dynamic range beam profiling for fluorescence microscopy.

    PubMed

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

    2014-10-01

    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. PMID:25362409

  5. Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity

    PubMed Central

    Zhang, Yuwei; Lucas, J. Matthew; Song, Ping; Beberwyck, Brandon; Fu, Qiang; Xu, Weilin; Alivisatos, A. Paul

    2015-01-01

    For the practical application of nanocatalysts, it is desirable to understand the spatiotemporal fluctuations of nanocatalytic activity at the single-nanoparticle level. Here we use time-lapsed superresolution mapping of single-molecule catalysis events on individual nanoparticles to observe time-varying changes in the spatial distribution of catalysis events on Sb-doped TiO2 nanorods and Au triangle nanoplates. Compared with the active sites on well-defined surface facets, the defects of the nanoparticle catalysts possess higher intrinsic reactivity but lower stability. Corners and ends are more reactive but also less stable than flat surfaces. Averaged over time, the most stable sites dominate the total apparent activity of single nanocatalysts. However, the active sites with higher intrinsic activity but lower stability show activity at earlier time points before deactivating. Unexpectedly, some active sites are found to recover their activity (“self-healing”) after deactivation, which is probably due to desorption of the adsorbate. Our superresolution measurement of different types of active catalytic sites, over both space and time, leads to a more comprehensive understanding of reactivity patterns and may enable the design of new and more productive heterogeneous catalysts. PMID:26150516

  6. Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity.

    PubMed

    Zhang, Yuwei; Lucas, J Matthew; Song, Ping; Beberwyck, Brandon; Fu, Qiang; Xu, Weilin; Alivisatos, A Paul

    2015-07-21

    For the practical application of nanocatalysts, it is desirable to understand the spatiotemporal fluctuations of nanocatalytic activity at the single-nanoparticle level. Here we use time-lapsed superresolution mapping of single-molecule catalysis events on individual nanoparticles to observe time-varying changes in the spatial distribution of catalysis events on Sb-doped TiO2 nanorods and Au triangle nanoplates. Compared with the active sites on well-defined surface facets, the defects of the nanoparticle catalysts possess higher intrinsic reactivity but lower stability. Corners and ends are more reactive but also less stable than flat surfaces. Averaged over time, the most stable sites dominate the total apparent activity of single nanocatalysts. However, the active sites with higher intrinsic activity but lower stability show activity at earlier time points before deactivating. Unexpectedly, some active sites are found to recover their activity ("self-healing") after deactivation, which is probably due to desorption of the adsorbate. Our superresolution measurement of different types of active catalytic sites, over both space and time, leads to a more comprehensive understanding of reactivity patterns and may enable the design of new and more productive heterogeneous catalysts. PMID:26150516

  7. Recent progress in the development of fluorescent, luminescent and colorimetric probes for detection of reactive oxygen and nitrogen species.

    PubMed

    Chen, Xiaoqiang; Wang, Fang; Hyun, Ji Young; Wei, Tingwen; Qiang, Jian; Ren, Xintong; Shin, Injae; Yoon, Juyoung

    2016-05-21

    Reactive oxygen (ROS) and nitrogen (RNS) species cause oxidative and nitrosative stresses, respectively. These stresses are implicated not only in diverse physiological processes but also in various pathological processes, including cancer and neurodegenerative disorders. In addition, some ROS and RNS in the environment are pollutants that threaten human health. As a consequence of these effects, sensitive methods, which can be employed to selectively monitor ROS and RNS in live cells, tissues and organisms as well as in environmental samples, are needed so that their biological roles can be understood and their concentrations in environmental samples can be determined. In this review, fluorescent, luminescent and colorimetric ROS and RNS probes, which have been developed since 2011, are comprehensively discussed. PMID:27092436

  8. High-resolution fluorescence microscopy of myelin without exogenous probes.

    PubMed

    Christensen, Pia Crone; Brideau, Craig; Poon, Kelvin W C; Döring, Axinia; Yong, V Wee; Stys, Peter K

    2014-02-15

    Myelin is a critical element of the central and peripheral nervous systems of all higher vertebrates. Any disturbance in the integrity of the myelin sheath interferes with the axon's ability to conduct action potentials. Thus, the study of myelin structure and biochemistry is critically important. Accurate and even staining of myelin is often difficult because of its lipid-rich nature and multiple tight membrane wraps, hindering penetration of immunoprobes. Here we show a method of visualizing myelin that is fast, inexpensive and reliable using the cross-linking fixative glutaraldehyde that produces strong, broad-spectrum auto-fluorescence in fixed tissue. Traditionally, effort is generally aimed at eliminating this auto-fluorescence. However, we show that this intrinsic signal, which is very photostable and particularly strong in glutaraldehyde-fixed myelin, can be exploited to visualize this structure to produce very detailed images of myelin morphology. We imaged fixed rodent tissues from the central and peripheral nervous systems using spectral confocal microscopy to acquire high-resolution 3-dimensional images spanning the visual range of wavelengths (400-750 nm). Mathematical post-processing allows accurate and unequivocal separation of broadband auto-fluorescence from exogenous fluorescent probes such as DAPI and fluorescently-tagged secondary antibodies. We additionally show the feasibility of immunohistochemistry with antigen retrieval, which allows co-localization of proteins of interest together with detailed myelin morphology. The lysolecithin model of de- and remyelination is shown as an example of a practical application of this technique, which can be routinely applied when high-resolution microscopy of central or peripheral myelinated tracts is required. PMID:24188810

  9. A high resolution solar atlas for fluorescence calculations

    NASA Technical Reports Server (NTRS)

    Hearn, M. F.; Ohlmacher, J. T.; Schleicher, D. G.

    1983-01-01

    The characteristics required of a solar atlas to be used for studying the fluorescence process in comets are examined. Several sources of low resolution data were combined to provide an absolutely calibrated spectrum from 2250 A to 7000A. Three different sources of high resolution data were also used to cover this same spectral range. The low resolution data were then used to put each high resolution spectrum on an absolute scale. The three high resolution spectra were then combined in their overlap regions to produce a single, absolutely calibrated high resolution spectrum over the entire spectral range.

  10. High-resolution reactive transport: A coupled parallel hydrogeochemical model

    NASA Astrophysics Data System (ADS)

    Beisman, J. J.; Maxwell, R. M.; Steefel, C. I.; Sitchler, A.; Molins, S.

    2013-12-01

    Subsurface hydrogeochemical systems are an especially complex component of the terrestrial environment and play host to a multitude of interactions. Parameterizations of these interactions are perhaps the least understood component of terrestrial systems, presenting uncertainties in the predictive understanding of biogeochemical cycling and transport. Thorough knowledge of biogeochemical transport processes is critical to the quantification of carbon/nutrient fluxes in the subsurface, and to the development of effective contaminant remediation techniques. Here we present a coupled parallel hydrogeochemical model, ParCrunchFlow, as a tool to further our understanding of governing processes and interactions in natural hydrogeochemical systems. ParCrunchFlow is a coupling of the reactive transport simulator CrunchFlow with the hydrologic model ParFlow. CrunchFlow is a multicomponent reactive flow and transport code that can be used to simulate a range of important processes and environments, including reactive contaminant transport, chemical weathering, carbon sequestration, biogeochemical cycling, and water-rock interaction. ParFlow is a parallel, three-dimensional, variably-saturated, coupled surface-subsurface flow and transport code with the ability to simulate complex topography, geology, and heterogeneity. ParCrunchflow takes advantage of the efficient parallelism built into Parflow, allowing the numerical simulation of reactive transport processes in chemically and physically heterogeneous media at high spatial resolutions. This model provides an ability to further examine the interactions and feedbacks between biogeochemical systems and complex subsurface flow fields. In addition to the details of model construction, results will be presented that show floodplain nutrient cycling and the effects of heterogeneity on small-scale mixing reactions at the Department of Energy's Old Rifle Legacy site.

  11. A scanning fluorescence spectroscopy of decorin under high pressure

    NASA Astrophysics Data System (ADS)

    Komoda, Takahito; Kim, Yun-Jung; Suzuki, Atsushi; Nishiumi, Tadayuki

    2013-06-01

    High pressure processing is able to tenderize not only meat but also intramuscular connective tissue, which is mainly composed of collagen. Decorin, one of the proteoglycans, binds to and stabilizes collagen fibrils. It has been suggested that structural weakening of intramuscular connective tissue may result from the disappearance of the decorin-collagen interaction. In this study, the fluorescence spectra and the surface hydrophobicity of decorin molecules were measured under high pressure in order to examine the resulting change in the tertiary structure. The fluorescence intensity and the surface hydrophobicity of decorin molecules both decreased with increasing applied pressure and with applied time at the constant applied pressure, respectively. The observations indicate that the native structure of decorin is maintained during 200 MPa pressurization for less than 30 min.

  12. Highly efficient blue electroluminescence based on thermally activated delayed fluorescence.

    PubMed

    Hirata, Shuzo; Sakai, Yumi; Masui, Kensuke; Tanaka, Hiroyuki; Lee, Sae Youn; Nomura, Hiroko; Nakamura, Nozomi; Yasumatsu, Mao; Nakanotani, Hajime; Zhang, Qisheng; Shizu, Katsuyuki; Miyazaki, Hiroshi; Adachi, Chihaya

    2015-03-01

    Organic compounds that exhibit highly efficient, stable blue emission are required to realize inexpensive organic light-emitting diodes for future displays and lighting applications. Here, we define the design rules for increasing the electroluminescence efficiency of blue-emitting organic molecules that exhibit thermally activated delayed fluorescence. We show that a large delocalization of the highest occupied molecular orbital and lowest unoccupied molecular orbital in these charge-transfer compounds enhances the rate of radiative decay considerably by inducing a large oscillator strength even when there is a small overlap between the two wavefunctions. A compound based on our design principles exhibited a high rate of fluorescence decay and efficient up-conversion of triplet excitons into singlet excited states, leading to both photoluminescence and internal electroluminescence quantum yields of nearly 100%. PMID:25485987

  13. Highly efficient blue electroluminescence based on thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Hirata, Shuzo; Sakai, Yumi; Masui, Kensuke; Tanaka, Hiroyuki; Lee, Sae Youn; Nomura, Hiroko; Nakamura, Nozomi; Yasumatsu, Mao; Nakanotani, Hajime; Zhang, Qisheng; Shizu, Katsuyuki; Miyazaki, Hiroshi; Adachi, Chihaya

    2015-03-01

    Organic compounds that exhibit highly efficient, stable blue emission are required to realize inexpensive organic light-emitting diodes for future displays and lighting applications. Here, we define the design rules for increasing the electroluminescence efficiency of blue-emitting organic molecules that exhibit thermally activated delayed fluorescence. We show that a large delocalization of the highest occupied molecular orbital and lowest unoccupied molecular orbital in these charge-transfer compounds enhances the rate of radiative decay considerably by inducing a large oscillator strength even when there is a small overlap between the two wavefunctions. A compound based on our design principles exhibited a high rate of fluorescence decay and efficient up-conversion of triplet excitons into singlet excited states, leading to both photoluminescence and internal electroluminescence quantum yields of nearly 100%.

  14. KIVA reactive hydrodynamics code applied to detonations in high vacuum

    NASA Astrophysics Data System (ADS)

    Greiner, N. Roy

    1989-08-01

    The KIVA reactive hydrodynamics code was adapted for modeling detonation hydrodynamics in a high vacuum. Adiabatic cooling rapidly freezes detonation reactions as a result of free expansion into the vacuum. After further expansion, a molecular beam of the products is admitted without disturbance into a drift tube, where the products are analyzed with a mass spectrometer. How the model is used for interpretation and design of experiments for detonation chemistry is explained. Modeling of experimental hydrodynamic characterization by laser-schlieren imaging and model-aided mapping that will link chemical composition data to particular volume elements in the explosive charge are also discussed.

  15. 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.

  16. 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. PMID:27378394

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

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueno, Kazuo

    1997-05-01

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

  18. 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.

  19. 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

  20. 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

  1. 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. PMID:27145171

  2. High throughput identification of promiscuous inhibitors from screening libraries with the use of a thiol-containing fluorescent probe

    PubMed Central

    McCallum, Megan M.; Nandhikonda, Premchendar; Temmer, Jonathan J.; Eyermann, Charles; Simeonov, Anton; Jadhav, Ajit; Yasgar, Adam; Maloney, David; Arnold, Leggy A.

    2013-01-01

    Testing small molecules for their ability to modify cysteine residues of proteins in the early stages of drug discovery is expected to accelerate our ability to develop more selective drugs with lesser side effects. In addition, this approach also enables the rapid evaluation of the mode of binding of new drug candidates in respect to thiol-reactivity and metabolism by glutathione. Herein, we describe the development of a fluorescence-based high throughput assay that allows the identification of thiol-reactive compounds. A thiol-containing fluorescent probe MSTI was synthesized and used to evaluate small molecules from the LOPAC collection of bioactive molecules. LOPAC compounds that are known to react with sulfur nucleophiles were identified with this assay, for example, irreversible protease inhibitors, nitric oxide releasing compounds, and proton-pump inhibitors. The results confirm that both electrophilic and redox reactive compounds can be quickly identified in a high throughput manner enabling the assessment of screening libraries in respect to thiol-reactive compounds. PMID:23446699

  3. Fluorescence spectroscopy: considerations for highly absorbing dissolved organic matter samples

    NASA Astrophysics Data System (ADS)

    Simone, B. E.; Miller, M.; McKnight, D. M.

    2009-12-01

    Fluorescence spectroscopy is a robust method for characterizing organic matter (OM). However, proper collection and correction of spectra are necessary to provide useful data. One important correction is the inner-filter correction, which primarily accounts for the inner-filter effect by adjusting for the wavelength dependent attenuation of emitted light by the solution prior to detection by the fluorometer. The most commonly used correction is based on an assumption that light is emitted at the center of the pathlength. Thus, the inner-filter effect is more pronounced in highly absorbing samples, and has the potential to skew the fluorescence spectra. For this study, the terrestrially derived Suwannee River fulvic acid (SRFA) and microbially derived Pony Lake fulvic acid (PLFA), from the International Humic Substances Society (IHSS), were diluted to incremental absorbances at a wavelength of 254 nm from 0.05 to 1.0 at pH 4 and 7. Three dimensional fluorescence spectra were measured and modeled with the Cory and McKnight (2005) parallel factor analysis (PARAFAC) model which resolves the fluorescence spectra into 13 components, including quinone-like and protein-like components. In the absence of inner-filter effects, plots of absorbance vs. loadings should be linear. Using the data from absorbance of 0.05 to 0.3, where the inner-filter affect is least pronounced, a linear regression was created and used as a baseline to predict component loadings at higher absorbance values in the absence of inner-filter effects. Results indicate that at absorbance values greater than 0.3, the commonly-used inner-filter correction is not able to remove the inner-filter effect. Therefore, in order to obtain reliable component loadings and correctly interpret the spectra, samples should be diluted to absorbance values less than 0.3 at 254 nm prior to collection of three dimensional fluorescence scans. The recommendation of a maximum absorbance of 0.3 agrees with the results of a

  4. 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.

  5. 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.

  6. 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

  7. Aqueous synthesis of near-infrared highly fluorescent platinum nanoclusters.

    PubMed

    García Fernández, Jenifer; Trapiella-Alfonso, Laura; Costa-Fernández, José M; Pereiro, Rosario; Sanz-Medel, Alfredo

    2015-05-29

    A one-step synthesis of near infrared fluorescent platinum nanoclusters (PtNCs) in aqueous medium is described. The proposed optimized procedure for PtNC synthesis is rather simple, fast and it is based on the direct metal reduction with NaBH4. Bidentated thiol ligands (lipoic acid) were selected as nanoclusters stabilizers in water media. The structural characterization revealed attractive features of the PtNCs, including small size, high water solubility, near-infrared luminescence centered at 680 nm, long-term stability and the highest quantum yield in water reported so far (47%) for PtNCs. Moreover, their stability in different pH media and an ionic strength of 0.2 M NaCl was studied and no significant changes in fluorescence emission were detected. In brief, they offer a new type of fluorescent noble metal nanoprobe with a great potential to be applied in several fields, including biolabeling and imaging experiments. PMID:25944823

  8. 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

  9. Scanning fluorescence detector for high-throughput DNA genotyping

    NASA Astrophysics Data System (ADS)

    Rusch, Terry L.; Petsinger, Jeremy; Christensen, Carl; Vaske, David A.; Brumley, Robert L., Jr.; Luckey, John A.; Weber, James L.

    1996-04-01

    A new scanning fluorescence detector (SCAFUD) was developed for high-throughput genotyping of short tandem repeat polymorphisms (STRPs). Fluorescent dyes are incorporated into relatively short DNA fragments via polymerase chain reaction (PCR) and are separated by electrophoresis in short, wide polyacrylamide gels (144 lanes with well to read distances of 14 cm). Excitation light from an argon laser with primary lines at 488 and 514 nm is introduced into the gel through a fiber optic cable, dichroic mirror, and 40X microscope objective. Emitted fluorescent light is collected confocally through a second fiber. The confocal head is translated across the bottom of the gel at 0.5 Hz. The detection unit utilizes dichroic mirrors and band pass filters to direct light with 10 - 20 nm bandwidths to four photomultiplier tubes (PMTs). PMT signals are independently amplified with variable gain and then sampled at a rate of 2500 points per scan using a computer based A/D board. LabView software (National Instruments) is used for instrument operation. Currently, three fluorescent dyes (Fam, Hex and Rox) are simultaneously detected with peak detection wavelengths of 543, 567, and 613 nm, respectively. The detection limit for fluorescein-labeled primers is about 100 attomoles. Planned SCAFUD upgrades include rearrangement of laser head geometry, use of additional excitation lasers for simultaneous detection of more dyes, and the use of detector arrays instead of individual PMTs. Extensive software has been written for automatic analysis of SCAFUD images. The software enables background subtraction, band identification, multiple- dye signal resolution, lane finding, band sizing and allele calling. Whole genome screens are currently underway to search for loci influencing such complex diseases as diabetes, asthma, and hypertension. Seven production SCAFUDs are currently in operation. Genotyping output for the coming year is projected to be about one million total genotypes (DNA

  10. 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.

  11. Highly conducting ZnSe films by reactive magnetron sputtering

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.

    1986-01-01

    This paper presents the results of an effort to deposit high-conductivity ZnSe on glass and conducting SnO2-coated glass substrates by reactive magnetron sputter deposition, using pure metal sputter targets of Zn and dopants such as In, Ga, and Al. Clear yellow ZnSe films were successfully obtained. By using substrate temperatures as low as 150 C, cosputtered dopants, and sputter parameters and H2Se injection rates which maximize the Zn-to-Se ratio in the films, ZnSe bulk resistivities have been lowered by up to seven orders of magnitude, reaching values as low as 20 ohm cm. The most effective dopant to data has been In, cosputtered with Zn in amounts leading to In atomic concentrations as high as 1.4 percent. Atomic-absorption measurements show an average 49.9/48.9 ratio of Zn to Se.

  12. Implementation of a new scanning method for high-resolution fluorescence tomography using thermo-sensitive fluorescent agents

    PubMed Central

    Nouizi, Farouk; Kwong, Tiffany C.; Cho, Jaedu; Lin, Yuting; Sampathkumaran, Uma; Gulsen, Gultekin

    2016-01-01

    Conventional fluorescence tomography provides images of the distribution of fluorescent agents within highly scattering media, but suffers from poor spatial resolution. Previously, we introduced a new method termed “temperature-modulated fluorescence tomography” (TM-FT) that generates fluorescence images with high spatial resolution. TM-FT first uses focused ultrasound to locate the distribution of temperature-sensitive fluorescence probes. Afterward, this a priori information is utilized to improve the performance of the inverse solver for conventional fluorescence tomography and reveal quantitatively accurate fluorophore concentration maps. However, the disadvantage of this novel method is the long data acquisition time as the ultrasound beam was scanned in a step-and-shoot mode. In this Letter, we present a new, fast scanning method that reduces the imaging time 40 fold. By continuously scanning the ultrasound beam over a 50 mm by 25 mm field-of-view, high-resolution fluorescence images are obtained in less than 29 min, which is critical for in vivo small animal imaging. PMID:26512501

  13. Implementation of a new scanning method for high-resolution fluorescence tomography using thermo-sensitive fluorescent agents.

    PubMed

    Nouizi, Farouk; Kwong, Tiffany C; Cho, Jaedu; Lin, Yuting; Sampathkumaran, Uma; Gulsen, Gultekin

    2015-11-01

    Conventional fluorescence tomography provides images of the distribution of fluorescent agents within highly scattering media, but suffers from poor spatial resolution. Previously, we introduced a new method termed "temperature-modulated fluorescence tomography" (TM-FT) that generates fluorescence images with high spatial resolution. TM-FT first uses focused ultrasound to locate the distribution of temperature-sensitive fluorescence probes. Afterward, this a priori information is utilized to improve the performance of the inverse solver for conventional fluorescence tomography and reveal quantitatively accurate fluorophore concentration maps. However, the disadvantage of this novel method is the long data acquisition time as the ultrasound beam was scanned in a step-and-shoot mode. In this Letter, we present a new, fast scanning method that reduces the imaging time 40 fold. By continuously scanning the ultrasound beam over a 50 mm by 25 mm field-of-view, high-resolution fluorescence images are obtained in less than 29 min, which is critical for in vivo small animal imaging. PMID:26512501

  14. 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.

  15. Highly photoluminescent polysilsesquioxane hybrids based on weakly fluorescent 1,8-naphthalic anhydride derivatives

    NASA Astrophysics Data System (ADS)

    Pan, Fei; Huang, Miao; Song, Jianhui; Wu, Meng; Xu, Min

    2016-07-01

    A series of highly fluorescent polysilsesquioxane materials based on 1,8-naphthalic anhydride derivatives(XNA) have been prepared. The XNAs were chemically bonded with the polysiloxane. Though the fluorescent intensities of the solution of XNAs with different substitutes make a great difference, some of them are even very weakly emissive, the fluorescent intensities of the corresponding solid polysilsesquioxane materials are strong. In this case, the electronic effect of the substitute became non-important. With restricted molecular motion and J-aggregation, some traditionally weakly fluorescent or non-fluorescent chromophoric organics due to the substituent effect may be used to prepare highly fluorescent materials.

  16. High refractive index substrates for fluorescence microscopy of biological interfaces with high z contrast

    PubMed Central

    Ajo-Franklin, Caroline M.; Kam, Lance; Boxer, Steven G.

    2001-01-01

    Total internal reflection fluorescence microscopy is widely used to confine the excitation of a complex fluorescent sample very close to the material on which it is supported. By working with high refractive index solid supports, it is possible to confine even further the evanescent field, and by varying the angle of incidence, to obtain quantitative information on the distance of the fluorescent object from the surface. We report the fabrication of hybrid surfaces consisting of nm layers of SiO2 on lithium niobate (LiNbO3, n = 2.3). Supported lipid bilayer membranes can be assembled and patterned on these hybrid surfaces as on conventional glass. By varying the angle of incidence of the excitation light, we are able to obtain fluorescent contrast between 40-nm fluorescent beads tethered to a supported bilayer and fluorescently labeled protein printed on the surface, which differ in vertical position by only tens of nm. Preliminary experiments that test theoretical models for the fluorescence-collection factor near a high refractive index surface are presented, and this factor is incorporated into a semiquantitative model used to predict the contrast of the 40-nm bead/protein system. These results demonstrate that it should be possible to profile the vertical location of fluorophores on the nm distance scale in real time, opening the possibility of many experiments at the interface between supported membranes and living cells. Improvements in materials and optical techniques are outlined. PMID:11717428

  17. Earle K. Plyler Prize Talk: Using High Resolution Electronic Spectroscopy to Probe Reactive Chemical Intermediates

    NASA Astrophysics Data System (ADS)

    Miller, Terry

    2009-03-01

    Gas phase chemical reactions, such as occur in atmospheric chemistry, combustion, plasma processing, etc. are of great importance to our economy and society. These reactions are typically very complex involving up to 1000's of elementary steps with a corresponding number of reactive chemical intermediates. Spectrospic diagnostics, based upon well analyzed and well understood spectra of the intermediates, are crucial for monitoring such reactions and unraveling their mechanisms. These spectral analyses often benefit from the guidance provided by quantum chemical calculations and conversely the molecular parameters, experimentally determined from the spectra, serve as ``gold standards'' for benchmarking such calculations. Such standards are especially valuable for reactive intermediates whose electronic or geometric structure is particularly complex because of electron-spin interactions, Jahn-Teller effects or other vibronic interactions, hindered internal motions, large molecular size and weight, etc. The organic alkoxy, RO., and peroxy, RO2., (R=alkyl group) free radicals are excellent examples of such species. The talk will focus on our recent characterization of these radicals via their ``high-resolution,'' mostly rotationally resolved, electronic spectra utilizing the techniques of laser induced fluorescence, stimulated emission pumping, and cavity ringdown spectroscopy. Selected spectra, their analysis, and the molecular information resulting therefrom will be discussed.

  18. Synthesis of highly fluorescent gold nanoclusters using egg white proteins.

    PubMed

    Joseph, Dickson; Geckeler, Kurt E

    2014-03-01

    Gold nanoclusters (AuNCs) have gained interest during the recent years because of their low toxicity and finer size for the bioimaging and biolabeling applications in comparison to the semiconductor quantum dot analogues. Diverse materials such as sulfur compounds, peptides, dendrimers, proteins, etc., are exploited for the preparation of AuNCs. Henceforth, highly fluorescent, water-soluble, and few atom-containing gold nanoclusters are created using a rapid, straightforward, and green method. In this regard for the first time chicken egg white (CEW), one of the most unique materials, is utilized in an aqueous solution under basic conditions at physiological temperature for the preparation of AuNCs. Tyrosine and tryptophan amino acid residues are responsible for the conversion of Au ions to Au(0) under alkaline condtions. CEW contains four major proteins of which the main constituent protein, ovalbumin also leads to the formation of the AuNCs with a higher fluorescence emission compared to the CEW. The ratios between the different reaction partners are very crucial, along with temperature and time for the preparation of AuNCs with high photoluminescence emission. The limited vibrational motion of the proteins under alkaline condition and the bulkiness of the proteins help in the formation of AuNCs. PMID:24321847

  19. 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. PMID:26515011

  20. 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.

  1. Molecular Dynamics Simulations of Highly Charged Green Fluorescent Proteins

    SciTech Connect

    Lau, E Y; Phillips, J L; Colvin, M E

    2009-03-26

    A recent experimental study showed that green fluorescent protein (GFP) that has been mutated to have ultra-high positive or negative net charges, retain their native structure and fluorescent properties while gaining resistance to aggregation under denaturing conditions. These proteins also provide an ideal test case for studying the effects of surface charge on protein structure and dynamics. They have performed classical molecular dynamics (MD) simulations on the near-neutral wildtype GFP and mutants with net charges of -29 and +35. They analyzed the resulting trajectories to quantify differences in structure and dynamics between the three GFPs. This analyses shows that all three proteins are stable over the MD trajectory, with the near-neutral wild type GFP exhibiting somewhat more flexibility than the positive or negative GFP mutants, as measured by the order parameter and changes in phi-psi angles. There are more dramatic differences in the properties of the water and counter ions surrounding the proteins. The water diffusion constant near the protein surface is closer to the value for bulk water in the positively charged GFP than in the other two proteins. Additionally, the positively charged GFP shows a much greater clustering of the counter ions (CL-) near its surface than corresponding counter ions (Na+) near the negatively charged mutant.

  2. Real-time Monitoring of Dissolved Organic Matter (DOM) Amount, Composition, Source and Reactivity Using Fluorescence Spectroscopy: Applications for Drinking Water Quality

    NASA Astrophysics Data System (ADS)

    Kraus, T. E.; Saraceno, J.; Downing, B. D.; Goldman, J. H.; Carpenter, K. D.; McGhee, G.; Bergamaschi, B. A.

    2010-12-01

    There is growing interest in the use of in situ, continuous fluorescence spectroscopy as a proxy for dissolved organic carbon (DOC) concentration. To date, in situ fluorometers designed to estimate DOC concentration are single wavelength sensors centered near the excitation/emission (ex/em) pair 370/460 nm. Additional information about dissolved organic matter (DOM) composition has only been obtainable from benchtop fluorometers that provide multi-spectral data. Changes in DOM composition are important as they provide insight into DOM source (e.g. terrestrial, algal, wastewater) and reactivity. Recent advances in sensor technology make it possible to build in situ instruments for measuring multiple fluorescence ex/em pairs, including pairs with excitations in the lower “deep UV” region (e.g. 270/340 nm) associated with fresher and more labile DOM pools. The deployment of multi-spectral sensors will provide real-time continuous data showing not only changes in DOM concentration, but also changes in composition. This information is particularly pertinent to drinking water utilities because a fraction of DOM reacts upon disinfection (e.g. chlorination and ozonation) to form toxic disinfection byproducts (DBPs) which are regulated by the EPA. To test this application, we designed a multi-wavelength sensor that will measure three ex/em pairs (370/470, 370/520 and 270/340 nm) for deployment near a drinking water intake on the Clackamas River in Oregon. Comparison of the continuous data with discrete sample data indicates these tools can track both quantitative and qualitative changes in the DOM pool. The availability of this type of continuous data in real time could enable utilities to minimize the formation of DBPs by continuously optimizing treatment plant operations in response to changes in source water. In addition, collection of high-frequency data will improve understanding of watershed DOM dynamics and help identify sources of DOM and DBP precursors, thereby

  3. Large enhancement of quantum dot fluorescence by highly scalable nanoporous gold.

    PubMed

    Zhang, Ling; Song, Yunke; Fujita, Takeshi; Zhang, Ye; Chen, Mingwei; Wang, Tza-Huei

    2014-02-26

    Dealloyed nanoporous gold (NPG) dramatically enhances quantum dot (QD) fluorescence by amplifying near-field excitation and increasing the radiative decay rate. Originating from plasmonic coupling, the fluorescence enhancement is highly dependent upon the nanopore size of the NPG. In contrast to other nanoengineered metallic structures, NPG exhibits fluorescence enhancement of QDs over a large substrate surface. PMID:24339211

  4. Substrate degradation in high-Rayleigh-number reactive convection

    NASA Astrophysics Data System (ADS)

    Ward, T. J.; Jensen, O. E.; Power, H.; Riley, D. S.

    2015-11-01

    We study buoyancy-induced convection of a solute in an ideal two-dimensional fluid-saturated porous medium, where the solute undergoes a second-order reaction with a chemical substrate that is fixed in the underlying matrix. Numerical simulations at high Rayleigh number show how a flow is established in which a thin dynamic boundary layer beneath the solute source feeds slender vertical plumes beneath. We examine how the substrate is reactively degraded, at a rate enhanced by convective mixing. For the case when the substrate is abundant, we derive a reduced-order model describing the slow degradation of the substrate, which is formulated as a novel one-dimensional free-boundary problem. Numerical simulations and the reduced model reveal how, when the reaction is rapid compared to the convective time scale, the plumes propagate deep into the flow domain with reaction confined to a narrow region at their base. In contrast, slow reaction allows plumes to fill the domain before degradation of the substrate proceeds homogeneously. An alternative model with a thin reaction front captures the rapid degradation of the substrate when the solute concentration is relatively high.

  5. Highly reactive electrophilic oxidants in cytochrome P450 catalysis

    SciTech Connect

    Newcomb, Martin . E-mail: men@uic.edu; Chandrasena, R. Esala P.

    2005-12-09

    The cytochrome P450 enzymes effect a wide range of oxidations in nature including difficult hydroxylation reactions of unactivated C-H. Most of the high energy reactions of these catalysts appear to involve highly electrophilic active species. Attempts to detect the reactive transients in the enzymes have met with limited success, but evidence has accumulated that two distinct electrophilic oxidants are produced in the P450 enzymes. The consensus electrophilic oxidant termed 'iron-oxo' is usually thought to be an analogue of Compound I, an iron(IV)-oxo porphyrin radical cation species, but it is possible that a higher energy electronic isomer of Compound I is required to account for the facility of the C-H oxidation reactions. The second electrophilic oxidant of P450 is speculative; circumstantial evidence suggests that this species is iron-complexed hydrogen peroxide, but this oxidant might be a second spin state of iron-oxo. This overview discusses recent studies directed at detection of the electrophilic oxidants in P450 enzymes and the accumulated evidence for two distinct species.

  6. 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.

  7. Strategies for the analysis of highly reactive pinacolboronate esters.

    PubMed

    Zhong, Qiqing; Ngim, Kenley K; Sun, Megan; Li, Jane; Deese, Alan; Chetwyn, Nik P

    2012-03-16

    Pinacolboronate esters (or boronic acid, pinacol esters) are widely used in the Suzuki coupling reaction to connect organic building blocks for the total synthesis of complex molecules. The 2-aminopyrimidine-5-pinacolboronate ester was used as a starting material in the synthesis of a development compound, necessitating a chromatographic purity method to assess its quality. This aryl pinacolboronate ester posed unique analytical challenges due to its facile hydrolysis to the corresponding boronic acid, which is nonvolatile and poorly soluble in organic solvents. This made GC and normal-phase HPLC analysis unsuitable. In reversed-phase mode, typical sample preparation and analysis conditions promoted rapid sample degradation to the boronic acid. To overcome these challenges, unconventional approaches were necessary in order to stabilize 2-aminopyrimidine-5-pinacolboronate ester, adequately solubilize its boronic acid, and produce acceptable separation and retention. The final method employed non-aqueous and aprotic diluent, and a reversed-phase separation using highly basic mobile phases (pH 12.4) with an ion pairing reagent. These strategies were successfully applied to several other reactive pinacolboronate esters for purity analysis, demonstrating broad applicability to this unique class of compounds. PMID:22321949

  8. Physical activity and high-sensitivity C-reactive protein.

    PubMed

    Plaisance, Eric P; Grandjean, Peter W

    2006-01-01

    Cardiovascular disease (CVD) remains one of the leading causes of death and disability in developed countries around the world despite the documented success of lifestyle and pharmacological interventions. This illustrates the multifactorial nature of atherosclerosis and the use of novel inflammatory markers as an adjunct to risk factor reduction strategies. As evidence continues to accumulate that inflammation is involved in all stages of the development and progression of atherosclerosis, markers of inflammation such as high-sensitivity C-reactive protein (CRP) may provide additional information regarding the biological status of the atherosclerotic lesion. Recent investigations suggest that physical activity reduces CRP levels. Higher levels of physical activity and cardiorespiratory fitness are consistently associated with 6-35% lower CRP levels. Longitudinal training studies that have demonstrated reductions in CRP concentrations range from 16% to 41%, an effect that may be independent of baseline levels of CRP, body composition or weight loss. The average change in CRP associated with physical activity appears to be at least as good, if not better, than currently prescribed pharmacological interventions in similar populations. The primary purpose of this review will be to present evidence from both cross-sectional and longitudinal investigations that physical activity lowers CRP levels in a dose-response manner. Finally, this review will examine factors such as body composition, sex, blood sample timing, diet and smoking, which may influence the CRP response to physical activity. PMID:16646631

  9. Temperature-modulated fluorescence tomography: modulating tissue temperature using HIFU for high-resolution in vivo fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Kwong, Tiffany C.; Nouizi, Farouk; Lin, Yuting; Sampathkumaran, Uma; Ahmed, Shaaz; Gulsen, Gultekin

    2013-03-01

    Low spatial resolution due to strong tissue scattering is one of the main barriers that prevent the wide-spread use of fluorescence tomography. To overcome this limitation, we previously demonstrated a new technique, temperature modulated fluorescence tomography (TM-FT), which relies on key elements: temperature sensitive ICG loaded pluronic nanocapsules and high intensity focused ultrasound (HIFU), to combine the sensitivity of fluorescence imaging with focused ultrasound resolution. While conventional fluorescence tomography measurements are acquired, the tissue is scanned by a HIFU beam and irradiated to produce a local hot spot, in which the temperature increases nearly 5K. The fluorescence emission signal measured by the optical detectors varies drastically when the hot spot overlays onto the location of the temperature dependent nanocapsules. The small size of the focal spot (~1.4 mm) up to a depth of 6 cm, allows imaging the distribution of these temperature sensitive agents with not only high spatial resolution but also high quantitative accuracy in deep tissue using a proper image reconstruction algorithm. Previously we have demonstrated this technique with a phantom study with nanocapsules sensitive to 20-25°C range. In this work, we will show the first nanocapsules optimized for in vivo animal imaging.

  10. Low Dissipative High Order Numerical Simulations of Supersonic Reactive Flows

    NASA Technical Reports Server (NTRS)

    Sjoegreen, B.; Yee, H. C.; Mansour, Nagi (Technical Monitor)

    2001-01-01

    The objective of this paper is to evaluate the performance of a newly developed low dissipative sixth-order spatial and fourth-order temporal scheme for viscous reactive flows interacting with shock waves that contain fine scale flow structures. The accuracy and efficiency of the scheme, and to what degree the scheme can capture the correct physical wave speeds of stiff reactive flows will be included.

  11. 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.

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

    PubMed

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

    2016-01-27

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

  13. 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

  14. High-resolution single-molecule fluorescence imaging of zeolite aggregates within real-life fluid catalytic cracking particles.

    PubMed

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

    2015-02-01

    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

  15. Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

    SciTech Connect

    Allison, S.W.

    2005-03-24

    Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded tests have involved surfaces such as blades, vanes, pistons, in-take valves, sheets of galvanneal steel, etc. The fluorescent coatings may be applied to small parts via sputtering methods or to large areas by mixture with inorganic binders. Presented here are results characterizing fluorescence rise times as a means of determining temperature from ambient to 700 C for Y{sub 2}O{sub 3}:Eu.

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

    PubMed

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

    2016-09-13

    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/cm(2)) live-cell SR imaging at ∼60-nm resolution at subsecond acquisition times for tens of time points over broad field of view. PMID:27562163

  17. Novel inhibitors for PRMT1 discovered by high-throughput screening using activity-based fluorescence polarization.

    PubMed

    Dillon, Myles B C; Bachovchin, Daniel A; Brown, Steven J; Finn, M G; Rosen, Hugh; Cravatt, Benjamin F; Mowen, Kerri A

    2012-07-20

    Protein arginine methyltransferases (PRMTs) catalyze the posttranslational methylation of arginine using S-adenosylmethionine (SAM) as a methyl-donor. The PRMT family is widely expressed and has been implicated in biological functions such as RNA splicing, transcriptional control, signal transduction, and DNA repair. Therefore, specific inhibitors of individual PRMTs have potentially significant research and therapeutic value. In particular, PRMT1 is responsible for >85% of arginine methyltransferase activity, but currently available inhibitors of PRMT1 lack specificity, efficacy, and bioavailability. To address this limitation, we developed a high-throughput screening assay for PRMT1 that utilizes a hyper-reactive cysteine within the active site, which is lacking in almost all other PRMTs. This assay, which monitors the kinetics of the fluorescence polarization signal increase upon PRMT1 labeling by a rhodamine-containing cysteine-reactive probe, successfully identified two novel inhibitors selective for PRMT1 over other SAM-dependent methyltransferases. PMID:22506763

  18. Genetic determinants of on-clopidogrel high platelet reactivity.

    PubMed

    Campo, Gianluca; Miccoli, Matteo; Tebaldi, Matteo; Marchesini, Jlenia; Fileti, Luca; Monti, Monia; Valgimigli, Marco; Ferrari, Roberto

    2011-01-01

    Clopidogrel has been used (alone or in association with aspirin) to prevent vascular complications in atherothrombotic patients, to prevent stent thrombosis (ST) in patients undergoing percutaneous coronary intervention (PCI) and as a long-term prevention of cardiovascular and cerebrovascular events. Unfortunately, it is important to note that there are a number of patients who, during clopidogrel therapy, show and maintain a high platelet reactivity (PR), similar to that observed before the start of antiplatelet therapy. Clopidogrel pro-drug is absorbed in the intestine and this process is influenced by P-glycoprotein-1 (P-GP). Its conversion into 2-oxo clopidogrel is regulated by cytochromes (CYP) called CYP2C19, CYP2B6 and CYP1A2. Whereas, the final transformation into the active metabolite is regulated by CYP called CYP2C19, CYP2C9, CYP2B6, CYP3A4, CYP3A5 and, as recently emerged, by the glycoprotein paraoxonase-1 (PON1). The genes encoding these enzymes are characterized by several polymorphisms. Some of these are able to modify the activity of proteins, reducing the concentration of active metabolite and the values of on-clopidogrel PR. Only one gene polymorphism (CYP2C19*17) increases the clopidogrel metabolization and so the clopidogrel-induced platelet inhibition. Several studies have clearly associated these gene polymorphisms to both ischemic and bleeding complications in patients receiving dual antiplatelet therapy. The aim of this review is to describe the principal gene polymorphisms influencing on-clopidogrel PR and their relationship with long-term clinical outcome. PMID:21627411

  19. Light up ClO(-) in live cells using an aza-coumarin based fluorescent probe with fast response and high sensitivity.

    PubMed

    Fan, Jiangli; Mu, Huiying; Zhu, Hao; Wang, Jingyun; Peng, Xiaojun

    2015-07-01

    Hypochlorous acid (HClO)/hypochlorite (ClO(-)), one of the reactive oxygen species (ROS), is a key microbicidal agent used for natural defense; however, HClO is also responsible for some human diseases. Although much effort has been made to develop HClO-selective fluorescent probes, many of them display a delayed response time and nanomole-sensitive probes are rare. In this study, we designed and synthesized an aza-coumarin based fluorescent probe AC-ClO for ClO(-) determination with fast response (completed within 2 min) and high sensitivity (detection limit is 25 nM). AC-ClO displayed a color change from pink to light yellow and a remarkable "turn-on" fluorescence response towards ClO(-). Confocal fluorescence microscopy experiments demonstrated that the probe could be applied for the live-cell imaging of exogenous and endogenous ClO(-). PMID:25997521

  20. 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.

  1. 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.

  2. 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.

  3. Development of fluorescence-based high-throughput screening assays: choice of appropriate instrumentation

    NASA Astrophysics Data System (ADS)

    Burns, David J.; Alder, Elisabeth; Fan, Yi-Hong; McKeegan, Evelyn; Warrior, Usha; Beutel, Bruce

    1998-04-01

    Fluorescence-based assays have become increasingly popular in high throughput screening for a variety of reasons (e.g. sensitivity). However, new screening technologies are pushing the limits of conventional fluorescence plate readers. For example, instruments that have optical sensitivities beyond most of the commercially available plate readers are required to reproducibly measure the fluorescence generated by the green fluorescent protein (GFP)--a novel reporter gene. Also, miniaturization of screening formats (with densities higher than the conventional 96-well plate) requires high resolution instrumentation to measure fluorescence. Several assays based on optical fluorescence measurements have been developed and screened in our Biological Screening group. These assays include various fluorescence-based protease assays (standard end-point and kinetic modes) and a functional cell-based screen using the green fluorescent protein as a reporter gene. The choice of instrumentation was the critical factor in the performance and success of each of these arrays. Data will be presented for the cell- based reporter assay including the type of instrumentation (fluorescence plate readers; fluorescence imaging systems) used for detection of GFP fluorescence.

  4. [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. PMID:23667995

  5. Recent Progress in Fluorescent Imaging Probes

    PubMed Central

    Pak, Yen Leng; Swamy, K. M. K.; Yoon, Juyoung

    2015-01-01

    Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn2+, Hg2+, Cu2+ and Au3+, and anions including cyanide and adenosine triphosphate (ATP). PMID:26402684

  6. Recent Progress in Fluorescent Imaging Probes.

    PubMed

    Pak, Yen Leng; Swamy, K M K; Yoon, Juyoung

    2015-01-01

    Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn(2+), Hg(2+), Cu(2+) and Au(3+), and anions including cyanide and adenosine triphosphate (ATP). PMID:26402684

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  8. High resolution fluorescent bio-imaging with electron beam excitation.

    PubMed

    Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

    2014-11-01

    We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure 1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig. 1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure 1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig. 1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i

  9. 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

  10. 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

  11. 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.; Ouldchikh, 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.

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

    PubMed

    Hoffman, A S; Debefve, L M; Bendjeriou-Sedjerari, A; Ouldchikh, 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. PMID:27475549

  13. Concerns in the application of fluorescent probes DCDHF-DA, DHR 123 and DHE to measure reactive oxygen species in vitro.

    PubMed

    Yazdani, Mazyar

    2015-12-25

    Reactive oxygen species (ROS) are formed in biological systems by partial reduction of molecular oxygen. The essential role of ROS in maintaining physiological health may be corrupted into oxidative stress by their overproduction or the exhaustion of antioxidant mechanisms. Many studies covering a broad range of methodologies have investigated ROS production and their toxic mechanisms of action. Of these methodologies, fluorometry has been among the preferred techniques. Three frequently used fluorescent probes for in vitro studies are 2',7'-dichlorodihydrofluorescein diacetate (DCDHF-DA), Dihydrorhodamine 123 (DHR 123) and Dihydroethidium (DHE). Apart from the unavoidable limitations of auto-oxidation, photo-oxidation and photo-conversion, there are also concerns relating to protocol modification for the improved monitoring of ROS. This paper aims to highlight such contributing factors, including cell culture conditions and the characteristics of individual fluorescent probes in the utilization of these selected probes in in vitro systems. PMID:26318276

  14. 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

  15. A hemicyanine-conjugated copolymer as a highly sensitive fluorescent thermometer.

    PubMed

    Shiraishi, Yasuhiro; Miyamoto, Ryo; Hirai, Takayuki

    2008-04-15

    A simple-structured copolymer, poly(NIPAM-co-HC), consisting of N-isopropylacrylamide (NIPAM) and 4-(4-dimethylaminostyryl)pyridine (hemicyanine, HC) units as thermoresponsive and fluorescent signaling parts, respectively, has been synthesized. This copolymer dissolved in water shows very weak fluorescence at <25 degrees C, while showing fluorescence enhancement at >25 degrees C. The fluorescence intensity increases with a rise in temperature and saturates at >40 degrees C, enabling temperature detection at 25-40 degrees C. The fluorescence enhancement is driven by a heat-induced phase transition of the polymer from coil to globule state. The HC units within the coil state polymer exist as the nonfluorescent benzenoid form; however, the less polar domain formed inside the globule state polymer leads to transformation of the HC unit to the fluorescent quinoid form, resulting in heat-induced fluorescence enhancement. The fluorescence intensity measured at 40 degrees C is >20-fold higher than the intensity at <25 degrees C, which is the highest enhancement value among the fluorescent thermometers proposed so far. The polymer shows reversible fluorescence enhancement/quenching, regardless of the heating/cooling process. In addition, the polymer shows high reusability with a simple recovery process. PMID:18315023

  16. High levels of reactive oxygen species in gold nanoparticle-targeted cancer cells following femtosecond pulse irradiation

    NASA Astrophysics Data System (ADS)

    Minai, Limor; Yeheskely-Hayon, Daniella; Yelin, Dvir

    2013-07-01

    Cancer cells could be locally damaged using specifically targeted gold nanoparticles and laser pulse irradiation, while maintaining minimum damage to nearby, particle-free tissue. Here, we show that in addition to the immediate photothermal cell damage, high concentrations of reactive oxygen species (ROS) are formed within the irradiated cells. Burkitt lymphoma B cells and epithelial breast cancer cells were targeted by antibody-coated gold nanospheres and irradiated by a few resonant femtosecond pulses, resulting in significant elevation of intracellular ROS which was characterized and quantified using time-lapse microscopy of different fluorescent markers. The results suggest that techniques that involve targeting of various malignancies using gold nanoparticles and ultrashort pulses may be more effective and versatile than previously anticipated, allowing diverse, highly specific set of tools for local cancer therapy.

  17. High levels of reactive oxygen species in gold nanoparticle-targeted cancer cells following femtosecond pulse irradiation.

    PubMed

    Minai, Limor; Yeheskely-Hayon, Daniella; Yelin, Dvir

    2013-01-01

    Cancer cells could be locally damaged using specifically targeted gold nanoparticles and laser pulse irradiation, while maintaining minimum damage to nearby, particle-free tissue. Here, we show that in addition to the immediate photothermal cell damage, high concentrations of reactive oxygen species (ROS) are formed within the irradiated cells. Burkitt lymphoma B cells and epithelial breast cancer cells were targeted by antibody-coated gold nanospheres and irradiated by a few resonant femtosecond pulses, resulting in significant elevation of intracellular ROS which was characterized and quantified using time-lapse microscopy of different fluorescent markers. The results suggest that techniques that involve targeting of various malignancies using gold nanoparticles and ultrashort pulses may be more effective and versatile than previously anticipated, allowing diverse, highly specific set of tools for local cancer therapy. PMID:23828378

  18. 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. PMID:26525155

  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. A novel fluorescent reagent for recognition of triplex DNA with high specificity and selectivity.

    PubMed

    Chen, Zongbao; Zhang, Huimi; Ma, Xiaoming; Lin, Zhenyu; Zhang, Lan; Chen, Guonan

    2015-11-21

    A fluorescent agent (DMT) was screened for recognizing triplex DNA with a specific and selective characteristic, which was embedded into the triplex DNA structure. The triplex DNA was firstly formed by a complementary target sequence through two distinct and sequential events. The conditions including pH and hybridization time, fluorescent agent concentration and embedding time were optimized in the experiment. Under the optimum conditions, the fluorescence signal was enhanced up to 9-fold in comparison with the DMT embedding into the ssDNA, dsDNA and G-quadruplexes. Under the same fluorescence conditions, the changes of the fluorescence signal were also investigated by several kinds of base mismatched DNAs in the experiment. The results showed that our biosensor provided excellent discrimination efficiency toward the perfectly mismatched target DNA with no formation of triplex DNA. We preliminarily deduced the mechanism of the fluorescent reagent for recognizing triplex DNA with high specificity and selectivity. PMID:26456316

  1. 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.

  2. Fluorescence of Dyes in Solutions with High Absorbance. Inner Filter Effect Correction

    PubMed Central

    Fonin, Alexander V.; Sulatskaya, Anna I.; Kuznetsova, Irina M.; Turoverov, Konstantin K.

    2014-01-01

    Fluorescence is a proven tool in all fields of knowledge, including biology and medicine. A significant obstacle in its use is the nonlinearity of the dependence of the fluorescence intensity on fluorophore concentration that is caused by the so-called primary inner filter effect. The existing methods for correcting the fluorescence intensity are hard to implement in practice; thus, it is generally considered best to use dilute solutions. We showed that correction must be performed always. Furthermore, high-concentration solutions (high absorbance) are inherent condition in studying of the photophysical properties of fluorescent dyes and the functionally significant interactions of biological macromolecules. We proposed an easy to use method to correct the experimentally recorded total fluorescence intensity and showed that informative component of fluorescence intensity numerically equals to the product of the absorbance and the fluorescence quantum yield of the object. It is shown that if dye molecules do not interact with each other and there is no reabsorption (as for NATA) and spectrofluorimeter provides the proportionality of the detected fluorescence intensity to the part of the absorbed light (that is possible for spectrofluorimeter with horizontal slits) then the dependence of experimentally detected total fluorescence intensity of the dye on its absorbance coincides with the calculated dependence and the correction factor for eliminating the primary inner filter effect can be calculated on the basis of solution absorbance. It was experimentally shown for NATA fluorescence in the wide range of absorbance (at least up to 60). For ATTO-425, which fluorescence and absorption spectra overlap, the elimination of the primary and secondary filter effects and additional spectral analysis allow to conclude that the most probable reason of the deviation of experimentally detected fluorescence intensity dependence on solution absorbance from the calculated dependence

  3. 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.

  4. 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.

  5. Impaired systemic vascular reactivity & raised high-sensitivity C reactive protein levels in chronic obstructive pulmonary disease

    PubMed Central

    Khare, Parul; Talwar, Anjana; Chandran, Dinu; Guleria, Randeep; Jaryal, Ashok Kumar; Kumar, Guresh; Trivedi, Anjali; Deepak, K.K.

    2016-01-01

    Background & objectives: Chronic obstructive pulmonary disease (COPD) is characterized by slowly progressive airflow limitaion, chronic lung inflammation and associated systemic manifestations. The objective of this preliminary study was to investigate the levels of high sensitivity C reactive protein (hs CRP) and tumour necrosis factor-α (TNF-α) as markers of systemic inflammation and assessment of systemic vascular reactivity that may play an important role in development of cardiovascular disease in COPD patients. Methods: Systemic vascular reactivity was assessed non-invasively by measuring peripheral pulse waveform changes during reactive hyperemia (RH) in 16 COPD patients and 14 controls by photoplethysmography technique (PPG). Parameters measured were pulse wave amplitude (PWA), slope and pulse transit time (PTT). Tumour necrosis factor-α (TNF-α) and hs CRP were measured as markers of inflammation. Results: PWA during the 1st, 2nd and 3rd minutes post release of occlusion were significantly higher than the baseline means in controls, whereas in the patient group there was no significant change in the PWA during any of the observed time periods following release of occlusion, in comparison to the baseline means. Similar results were observed in slope values for patients and controls. Maximum percentage change in PWA during RH with reference to baseline was significantly lower in patients as compared to controls (26.78±20.19 vs 57.20±19.80%, P<0.001). Maximum percentage change in slope during RH with reference to baseline was significantly lower in patients as compared to controls (19.77±10.73 vs 39.25±13.49%, P<0.001). A vascular tone response as represented by PTT was also impaired in the 3rd minute of RH as compared to baseline mean values in COPD patients only. Interpretation & conclusions: Our findings showed raised hs CRP levels and impaired systemic vascular reactivity in COPD patients. Whether these may increase the risk of cardiovascular

  6. Birth Weight, Current Anthropometric Markers, and High Sensitivity C-Reactive Protein in Brazilian School Children

    PubMed Central

    Pellanda, Lucia Campos

    2015-01-01

    Studies have shown associations of birth weight with increased concentrations of high sensitivity C-reactive protein. This study assessed the relationship between birth weight, anthropometric and metabolic parameters during childhood, and high sensitivity C-reactive protein. A total of 612 Brazilian school children aged 5–13 years were included in the study. High sensitivity C-reactive protein was measured by particle-enhanced immunonephelometry. Nutritional status was assessed by body mass index, waist circumference, and skinfolds. Total cholesterol and fractions, triglycerides, and glucose were measured by enzymatic methods. Insulin sensitivity was determined by the homeostasis model assessment method. Statistical analysis included chi-square test, General Linear Model, and General Linear Model for Gamma Distribution. Body mass index, waist circumference, and skinfolds were directly associated with birth weight (P < 0.001, P = 0.001, and P = 0.015, resp.). Large for gestational age children showed higher high sensitivity C-reactive protein levels (P < 0.001) than small for gestational age. High birth weight is associated with higher levels of high sensitivity C-reactive protein, body mass index, waist circumference, and skinfolds. Large for gestational age altered high sensitivity C-reactive protein and promoted additional risk factor for atherosclerosis in these school children, independent of current nutritional status. PMID:25874126

  7. 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.

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

    PubMed

    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 (CC) 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 (210nm) and the two well-resolved emission peaks separated by 140nm. 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 50s), 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. PMID:27236136

  9. 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.

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

    PubMed

    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

    2016-07-12

    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

  11. 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

  12. 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.

  13. Sensitive and selective tumor imaging with novel and highly activatable fluorescence strategies

    NASA Astrophysics Data System (ADS)

    Urano, Yasuteru

    2008-02-01

    Nowadays, several tumor imaging modalities such as MRI, PET and fluorescence imaging techniques have been extensively investigated. One of the central problems associated with these conventional tumor-targeted imaging methods, however, is the fact that the signal contrast between tumor and surrounding tissues relies on the efficient targeting to the tumor and the rapid sequestration or excretion of unbound agent. Among these modalities, only fluorescence imaging technique has a significant feature, in that great signal activation could be achieved which potentially leads to the selective imaging of cancer with higher tumor-to-background ratio. In this symposium, I will present some examples of fluorescence cancer imaging based on highly activatable strategies with using precisely designed novel fluorescence probes. Recently, we developed highly sensitive fluorescence probes for β-galactosidase which is applicable for living cell system. By utilizing these probes, we could establish a novel and highly activatable strategy for sensitive and selective optical imaging of imbedded tumor in the peritoneum. We took a two step procedure in that a lectin is used to localize β-galactosidase to cancer cells as an activating enzyme, and subsequent administration of a highly-sensitive fluorescence probe for the enzyme have afforded remarkable fluorescence activation selectively in tumor mass. Since the tumor-targeted enzyme can catalyze numerous substrate turnovers, a great number of fluorescent molecules could be produced and hence the rapid and sensitive detection of tumor in vivo with high tumor-to-background ratio could be achieved. Moreover, the consequent close-up investigation using fluorescence microscopy revealed that cancer microfoci as small as 200 μm could be successfully visualized.

  14. 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

  15. Development and biological applications of high-resolution ion beam induced fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Zhaohong, Mi

    High-resolution fluorescence microscopy has become an essential tool in both biological and biomedical sciences, to directly visualize biological processes at the cellular and subcellular levels through specific fluorescence labeling. Among the fluorescence microscopy techniques, mega-electron-volt (MeV) ion-induced fluorescence microscopy has unique advantages because MeV ions can penetrate through biological cells with little deflection in their trajectories. The state-of-the-art bioimaging facility in the Centre for Ion Beam Applications, National University of Singapore can achieve sub-30 nm spatial resolutions for structural imaging of biological cells, which is well below the diffraction limits imposed by optical microscopy. Our aim is to achieve similar spatial resolutions for Ion Beam Induced Fluorescence Imaging. (Abstract shortened by UMI.).

  16. Highly H2O2-sensitive electrospun quantum dots nanocomposite films for fluorescent biosensor.

    PubMed

    Tan, Longfei; He, Xiaolong; Chen, Dong; Wu, Xiaoli; Li, Hongbo; Ren, Xiangling; Meng, Xianwei; Tang, Fangqiong

    2013-01-01

    Bright CdSe quantum dots (QDs)/polycaprolactone (PCL) nanocomposite fluorescent films were fabricated by electronspinning. By using chloroform and N,N-dimethylformamide as electronspinning solvent, the oil-soluble CdSe QDs were uniformly distributed in PCL fibers, and were directly employed as optical probe without any modification processing. The fluorescences of CdSe QDs/PCL nanocomposite films were quickly quenched when the films were contacted with H2O2, solution. In the presence of glucose oxidase (GOD), the fluorescence intensities of these fluorescent films exhibit a liner change with the concentrations of glucose. The H2O2-sensitive electrospun QDs nanocomposite films are highly uniform and repeatable, demonstrating the potential to fabricate stable, sensitive and recyclable fluorescent biosensor for the detection different H2O2-generating oxidases and their substrates. PMID:23627067

  17. 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.

  18. 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.

  19. 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. PMID:25867455

  20. 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

  1. 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.

  2. Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering

    SciTech Connect

    Moreira, Milena A.; Törndahl, Tobias; Katardjiev, Ilia; Kubart, Tomas

    2015-03-15

    Aluminum nitride thin films were deposited by reactive high power impulse magnetron sputtering (HiPIMS) and pulsed direct-current on Si (100) and textured Mo substrates, where the same deposition conditions were used for both techniques. The films were characterized by x-ray diffraction and atomic force microscopy. The results show a pronounced improvement in the AlN crystalline texture for all films deposited by HiPIMS on Si. Already at room temperature, the HiPIMS films exhibited a strong preferred (002) orientation and at 400 °C, no contributions from other orientations were detected. Despite the low film thickness of only 200 nm, an ω-scan full width at half maximum value of 5.1° was achieved on Si. The results are attributed to the high ionization of sputtered material achieved in HiPIMS. On textured Mo, there was no significant difference between the deposition techniques.

  3. Phthalocyanine dye as an extremely photostable and highly fluorescent near-infrared labeling reagent

    NASA Astrophysics Data System (ADS)

    Peng, Xinzhan; Draney, Daniel R.; Volcheck, William M.; Bashford, Gregory R.; Lamb, Donald T.; Grone, Daniel L.; Zhang, Yonghong; Johnson, Craig M.

    2006-02-01

    Current organic fluorophores used as labeling reagents for biomolecule conjugation have significant limitations in photostability. This compromises their performance in applications that require a photostable fluorescent reporting group. For example, in molecular imaging and single molecule microscopy, photostable fluorescent labels are important for observing and tracking individual molecular events over extended period of time. We report in this paper an extremely photostable and highly fluorescent phthalocyanine dye, IRDye TM 700DX, as a near-infrared fluorescence labeling reagent to conjugate with biomolecules. This novel water-soluble silicon phthalocyanine dye has an isomericly pure chemical structure. The dye is about 45 to 128 times more photostable than current near-IR fluorophores, e.g. Alexa Fluor"R"680, Cy TM 5.5, Cy TM 7 and IRDye TM 800CW dyes; and about 27 times more photostable than tetramethylrhodamine (TMR), one of the most photostable organic dyes. This dye also meets all the other stringent requirements as an ideal fluorophore for biomolecules labeling such as excellent water solubility, no aggregation in high ionic strength buffer, large extinction coefficient and high fluorescent quantum yield. Antibodies conjugated with IRDye TM 700DX at high D/P ratio exist as monomeric species in high ionic buffer and have bright fluorescence. The IRDye TM 700DX conjugated antibodies generate sensitive, highly specific detection with very low background in Western blot and cytoblot assays.

  4. Synthesis of a highly HOCl-selective fluorescent probe and its use for imaging HOCl in cells and organisms.

    PubMed

    Chen, Xiaoqiang; Lee, Kyung-Ah; Ren, Xintong; Ryu, Jae-Chan; Kim, Gyungmi; Ryu, Ji-Hwan; Lee, Won-Jae; Yoon, Juyoung

    2016-07-01

    During infection, nicotinamide adenine dinucleotide phosphate-oxidase of innate immune cells generates important microbicidal reactive oxygen species (ROS) such as hypochlorous acid (HOCl) to kill the invading pathogens. However, excess amounts of HOCl induce oxidative damage of functional biomolecules such as DNA and proteins, which may cause chronic inflammatory diseases. Herein, we outline protocols for the preparation of a rhodamine-based HOCl probe, as well as applications thereof, with which to detect HOCl in living cells and organisms. The probe (R19S) can be prepared from a commercially available rhodamine, rhodamine 6G, in two steps. When R19S is treated with HOCl, the sulfur atom is replaced by an oxygen atom, resulting in opening of the lactone ring; thus, nonfluorescent R19S is converted to highly fluorescent rhodamine 19 (R19). R19S exhibits high selectivity for HOCl over other ROS and high sensitivity in a weakly acidic environment. In addition, we describe fluorescence imaging assays of HOCl in mouse neutrophils and Drosophila targeted using this probe. The approximate amount of time required to synthesize the probe is 2-3 d, after which it can be used for up to 5 h in the bioimaging of living cells. PMID:27281649

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

    PubMed

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

    2016-01-01

    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

  6. 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

  7. 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

  8. 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

  9. Laser-induced fluorescence studies of polycyclic aromatic hydrocarbons (PAH) vapors at high temperatures.

    PubMed

    Chi, Z; Cullum, B M; Stokes, D L; Mobley, J; Miller, G H; Hajaligol, M R; Vo-Dinh, T

    2001-06-01

    In this work, we present the fluorescence spectra of anthracene and pyrene vapors at different elevated temperatures (from 150 to 650 degrees C) excited with the 337 nm line of a nitrogen laser. We describe the high temperature effects on the resulting spectral properties including spectral intensity, spectral bandwidth and spectral shift. We found that the PAH fluorescence spectral bandwidths become very broad as the temperature increases. The broadening is mainly due to thermal vibrational sequence congestion. We also have found that the fluorescence intensity of pyrene vapor increases with increasing temperature, which results from the increase of the pyrene vapor absorption cross section at 337 nm. PMID:11446693

  10. Highly efficient fluorescence detection in picoliter volume liquid-core waveguides

    SciTech Connect

    Yin Dongliang; Barber, John P.; Hawkins, Aaron R.; Schmidt, Holger

    2005-11-21

    We report loss improvement and fluorescence detection in integrated antiresonant reflecting optical waveguides with liquid cores. The minimum waveguide loss is reduced to 0.33/cm by compensating for thickness variations in the fabrication process. We demonstrate fluorescence detection from as few as 490 molecules in a 57 pl core using these optimized waveguides. We measure angular fluorescence collection factors as high as 15% per facet in good agreement with theory. This demonstrates the potential of integrated hollow-core waveguides as optical sensors for single-molecule spectroscopy.

  11. High photostability and enhanced fluorescence of gold nanoclusters by silver doping

    NASA Astrophysics Data System (ADS)

    Le Guével, Xavier; Trouillet, Vanessa; Spies, Christian; Li, Ke; Laaksonen, Timo; Auerbach, Dagmar; Jung, Gregor; Schneider, Marc

    2012-11-01

    Gold nanoclusters prepared with a controlled amount of Ag exhibit intense fluorescence with a quantum yield of ~16% and a ``quasi-monoexponential'' long lifetime of >200 ns. Characterization of the luminescent probes indicates high photostability and easy detection in cells. Additionally, fluorescence enhancement in the presence of proteins was found.Gold nanoclusters prepared with a controlled amount of Ag exhibit intense fluorescence with a quantum yield of ~16% and a ``quasi-monoexponential'' long lifetime of >200 ns. Characterization of the luminescent probes indicates high photostability and easy detection in cells. Additionally, fluorescence enhancement in the presence of proteins was found. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30653k

  12. 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.

  13. An aqueous fluorescent probe for Hg(2+) detection with high selectivity and sensitivity.

    PubMed

    Fang, Qian; Liu, Qian; Song, Xiangzhi; Kang, Jian

    2015-12-01

    An aqueous fluorescent probe, 1, was developed for the rapid detection of Hg(2+) with high sensitivity and excellent selectivity. Upon the addition of Hg(2+) in pure aqueous media, the Hg(2+)-mediated hydrolysis of vinyl ether and subsequent cyclization reactions converted probe 1 into the corresponding iminocoumarin dye, which is strongly fluorescent when excited. The application of this probe for the detection of intracellular Hg(2+) was successfully demonstrated in living cells. PMID:25761896

  14. 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. PMID:26485176

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

    PubMed

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

    2016-03-24

    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. PMID:26961769

  16. Fluorescence lifetime plate reader: Resolution and precision meet high-throughput

    NASA Astrophysics Data System (ADS)

    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.

  17. 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.

  18. Separating Reflective and Fluorescent Components Using High Frequency Illumination in the Spectral Domain.

    PubMed

    Fu, Ying; Lam, Antony; Sato, Imari; Okabe, Takahiro; Sato, Yoichi

    2016-05-01

    Hyperspectral imaging is beneficial to many applications but most traditional methods do not consider fluorescent effects which are present in everyday items ranging from paper to even our food. Furthermore, everyday fluorescent items exhibit a mix of reflection and fluorescence so proper separation of these components is necessary for analyzing them. In recent years, effective imaging methods have been proposed but most require capturing the scene under multiple illuminants. In this paper, we demonstrate efficient separation and recovery of reflectance and fluorescence emission spectra through the use of two high frequency illuminations in the spectral domain. With the obtained fluorescence emission spectra from our high frequency illuminants, we then describe how to estimate the fluorescence absorption spectrum of a material given its emission spectrum. In addition, we provide an in depth analysis of our method and also show that filters can be used in conjunction with standard light sources to generate the required high frequency illuminants. We also test our method under ambient light and demonstrate an application of our method to synthetic relighting of real scenes. PMID:26336113

  19. Fluorescence lifetime plate reader: Resolution and precision meet high-throughput

    PubMed Central

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

    2014-01-01

    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. PMID:25430092

  20. 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. PMID:17444525

  1. 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

  2. Li2 - Li reactive collisions at high initial j

    NASA Astrophysics Data System (ADS)

    Rosenberry, Mark; Marhatta, Ramesh; Stewart, Brian

    2014-05-01

    Inelastic molecular collisions are a fundamental process in astronomy and chemistry. We are studying collisions of 7Li2 with 7Li in a heat pipe oven, and looking for nuclear parity-changing events that signal a chemical reaction. Previous work in our group studied such reactions for low initial j; we are now working to collect data for the case of high initial j, where quasi-resonant phenomena occur. We have also incorporated new corrections for multiple collisions in our analysis. Quasi-classical trajectory calculations are used to model these reactions and extract physical insight.

  3. 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.

  4. 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.

  5. Highly fluorescent colloids based on rhodamine 6G, modified layered silicate, and organic solvent.

    PubMed

    Bujdák, Juraj; Iyi, Nobuo

    2012-12-15

    Synthetic layered silicate saponite was modified with dodecyltrimethylammonium (C12), octadecyltrimethylammonium (C18), and dioctadecyldimethylammonium (2C18) cations for use as sorbents of the laser dye, rhodamine 6G (R6G). Via solvent exchange, transparent colloids in xylene were prepared and investigated using absorption and fluorescence spectroscopies. Molecular aggregation and partial quenching of the fluorescence were observed for the colloids based on 2C18 cations. Maximal fluorescence yields were observed for the colloids with C12 and C18 cations. Transparent gels without an apparent loss of luminescent efficiency could be prepared by concentrating the colloids. These highly fluorescent colloids and gels represent new types of materials with interesting optical properties. PMID:22995248

  6. Fluorescent Protein Nanowire-Mediated Protein Microarrays for Multiplexed and Highly Sensitive Pathogen Detection.

    PubMed

    Men, Dong; Zhou, Juan; Li, Wei; Leng, Yan; Chen, Xinwen; Tao, Shengce; Zhang, Xian-En

    2016-07-13

    Protein microarrays are powerful tools for high-throughput and simultaneous detection of different target molecules in complex biological samples. However, the sensitivity of conventional fluorescence-labeling protein detection methods is limited by the availability of signal molecules for binding to the target molecule. Here, we built a multifunctional fluorescent protein nanowire (FNw) by harnessing self-assembly of yeast amyloid protein. The FNw integrated a large number of fluorescent molecules, thereby enhancing the fluorescent signal output in target detection. The FNw was then combined with protein microarray technology to detect proteins derived from two pathogens, including influenza virus (hemagglutinin 1, HA1) and human immunodeficiency virus (p24 and gp120). The resulting detection sensitivity achieved a 100-fold improvement over a commercially available detection reagent. PMID:27315221

  7. Premixed direct injection nozzle for highly reactive fuels

    SciTech Connect

    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.

  8. 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.

  9. 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. PMID:27591625

  10. 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.

  11. Future use of silicon photomultipliers for the fluorescence detection of ultra-high-energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Stephan, Maurice; Hebbeker, Thomas; Lauscher, Markus; Meurer, Christine; Niggemann, Tim; Schumacher, Johannes

    2011-10-01

    A sophisticated technique to measure extensive air showers initiated by ultra-high-energy cosmic rays is by means of fluorescence telescopes. Secondary particles of the air shower excite nitrogen molecules of the atmosphere, which emit fluorescence light when they de-excite. Due to their high photon detection efficiency (PDE) silicon photomultipliers (SiPMs) promise to increase the sensitivity of todays fluorescence telescopes which use photomultiplier tubes - for example the fluorescence detector of the Pierre Auger Observatory. On the other hand drawbacks like a small sensitive area, a strong temperature dependency and a high noise rate have to be managed. We present plans for a prototype fluorescence telescope using SiPMs and a special light collecting optical system of Winston cones to increase the sensitive area. In this context we made measurements of the relative PDE of SiPMs depending on the incident angle of light. The results agree with calculations based on the Fresnel equations. Furthermore, measurements of the brightness of the night sky are presented since this photon flux is the main background to the fluorescence signals of the extensive air showers. To compensate the temperature dependency of the SiPM, frontend electronics make use of temperature sensors and microcontrollers to directly adjust the bias-voltage according to the thermal conditions. To reduce the noise rate we study the coincidence of several SiPMs signals triggered by cosmic ray events. By summing up these signals the SiPMs will constitute a single pixel of the fluorescence telescope.

  12. 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...

  13. 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. PMID:26922047

  14. 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...

  15. 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...

  16. Highly selective ensembles for D-fructose based on fluorescent method in aqueous solution

    NASA Astrophysics Data System (ADS)

    Wang, Zhijun; Lei, Haiying; Zhou, Chengyong; Wang, Guofeng; Feng, Liheng

    2012-06-01

    Three highly sensitive and selective switches for monosaccharides were composed by anionic polyelectrolyte PPPSO3Na and cationic viologen quencheres BBVs. The sensing processes of three ensembles (PPPSO3Na/o-BBV, PPPSO3Na/m-BBV and PPPSO3Na/p-BBV) to common seven monosaccharides have been determined by fluorescence spectra at pH 7.4 buffer solution. The results show that the three sensing ensembles all embody higher selectivity and sensitivity for D-fructose with reversible "on-off-on" fluorescence response. The research results can provide a new mode for developing highly selective probes.

  17. High quality fluorescent cellulose nanofibers from endemic rice husk: isolation and characterization.

    PubMed

    Kalita, E; Nath, B K; Deb, P; Agan, F; Islam, Md R; Saikia, K

    2015-05-20

    Cellulose nanofibers (CNFs) with high crystallinity and purity were isolated from two endemic rice husk varieties using a hydrothermal approach followed by acid-alkali treatments and mechanical disruption. The CNFs isolated had a mean diameter of ∼ 35 nm. The TGA and DTG profiles showed good thermostability of the CNFs. The CNFs also showed a prominent photoluminescence peak at 404 nm with high quantum yield (∼ 58%). This is the first report on the native fluorescence property of nanocellulose in absence of any conjugated fluorescence molecule/dye. The CNFs further demonstrated appreciable hemocompatibility in the hemolysis test, exhibiting its potential for biomedical applications. PMID:25817673

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

    PubMed

    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

    2016-12-01

    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. PMID:27299653

  19. 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.

  20. 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.

  1. Unusual high fluorescence of two nitro-distyrylbenzene-like compounds induced by CT processes affecting the fluorescence/intersystem-crossing competition.

    PubMed

    Carlotti, B; Elisei, F; Mazzucato, U; Spalletti, A

    2015-06-14

    Two nitro-substituted 1,4-distyrylbenzene-like compounds have been investigated using stationary and time-resolved (ns/fs) spectrometric techniques as a function of solvent polarity. In the two compounds the central benzene ring is substituted with a p-nitrostyryl group at one side while, at the other side, compound 1 (asymmetric) bears a pyrid-4-ylethenyl group and compound 2 (symmetric) another p-nitrostyryl group. The solvent dependent intramolecular charge transfer (ICT) in the singlet manifold was found to strongly affect the competition among fluorescence, intersystem crossing and trans-cis photoisomerization. The presence of nitro-groups in the 1,4-distyrylbenzene skeleton causes the usual strong decrease of fluorescence in favour of intersystem crossing to a reactive triplet state. However, the favoured formation of the ICT state in polar solvents induces an unexpected important increase of the fluorescence quantum yield (three/two order of magnitude for the nitro and dinitro derivatives, respectively). The ultrafast spectral transients helped to understand the solvent effects measured by stationary techniques and gave information on the dynamics of the locally excited singlet state ((1)LE*) and the (1)ICT* state, fast produced in polar solvents. Evidence of dual fluorescence in a limited range of solvent polarity, particularly for compound 1, is also reported. The role of an upper triplet state in a non-polar solvent is discussed also based on quantum-mechanical calculations (TD-DFT method) and temperature effects on the photophysical parameters. PMID:25975235

  2. Facile synthesis of N, S-codoped fluorescent carbon nanodots for fluorescent resonance energy transfer recognition of methotrexate with high sensitivity and selectivity.

    PubMed

    Wang, Weiping; Lu, Ya-Chun; Huang, Hong; Wang, Ai-Jun; Chen, Jian-Rong; Feng, Jiu-Ju

    2015-02-15

    In this report, N, S-codoped fluorescent carbon nanodots (NSCDs) were prepared by a facile, simple, low-cost, and green thermal treatment of ammonium persulfate, glucose, and ethylenediamine. The as-prepared NSCDs displayed bright blue emission with a relatively high fluorescent quantum yield of 21.6%, good water solubility, uniform morphology, and excellent chemical stability, compared to pure CDs. The fluorescence of NSCDs can be significantly quenched by methotrexate (MTX) via fluorescence resonance energy transfer (FRET) between NSCDs and MTX, which was used for highly selective and sensitive detection of MTX with a wide linear range up to 50.0 μM and a low detection limit of 0.33 nM (S/N = 3). Moreover, this method was explored for practical detection of MTX in human serum with satisfied results. PMID:25310482

  3. 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

  4. Sonochemical synthesis of highly fluorescent glutathione-stabilized Ag nanoclusters and S2- sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Tingyao; Rong, Mingcong; Cai, Zhimin; Yang, Chaoyong James; Chen, Xi

    2012-06-01

    A facile one-pot sonochemical approach is presented to prepare highly blue-emitting Ag nanoclusters (AgNCs) using glutathione as a stabilizing agent in aqueous solution. The as-prepared AgNCs can be applied in the selective detection of S2- with a limit of detection of 2 nM based on fluorescence quenching.A facile one-pot sonochemical approach is presented to prepare highly blue-emitting Ag nanoclusters (AgNCs) using glutathione as a stabilizing agent in aqueous solution. The as-prepared AgNCs can be applied in the selective detection of S2- with a limit of detection of 2 nM based on fluorescence quenching. Electronic supplementary information (ESI) available: Experimental procedures of fluorescent AgNCs synthesis and Fig. S1-S6. See DOI: 10.1039/c2nr30718a

  5. High-speed confocal fluorescence lifetime imaging microscopy by analog mean-delay method

    NASA Astrophysics Data System (ADS)

    Won, Youngjae; Kim, Donguk; Yang, Wenzhong; Kim, Dug Y.

    2010-02-01

    We have demonstrated the high-speed confocal fluorescence lifetime imaging microscopy (FLIM) by analog mean-delay (AMD) method. The AMD method is a new signal processing technique for calculation of fluorescence lifetime and it is very suitable for the high-speed confocal FLIM with good accuracy and photon economy. We achieved the acquisition speed of 7.7 frames per second for confocal FLIM imaging. Here, the highest photon detection rate for one pixel was larger than 125 MHz and averaged photon detection rate was more than 62.5 MHz. Based on our system, we successfully obtained a sequence of confocal fluorescence lifetime images of RBL-2H3 cell labeled with Fluo-3/AM and excited by 4αPDD (TRPV channel agonist) within one second.

  6. Development of a High-performance Optical System and Fluorescent Converters for High-resolution Neutron Imaging

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Yasuda, R.; Iikura, H.; Nojima, T.; Matsubayashi, M.

    Two novel devices for use in neutron imaging technique are introduced. The first one is a high-performance optical lens for video camera systems. The lens system has a magnification of 1:1 and an F value of 3. The optical resolution is less than 5 μm. The second device is a high-resolution fluorescent plate that converts neutrons into visible light. The fluorescent converter material consists of a mixture of 6LiF and ZnS(Ag) fine powder, and the thickness of the converter is material is as little as 15 μm. The surface of the plate is coated with a 1 μm-thick gadolinium oxide layer. This layer is optically transparent and acts as an electron emitter for neutron detection. Our preliminary results show that the developed optical lens and fluorescent converter plates are very promising for high-resolution neutron imaging.

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

    PubMed

    Higuchi, Takahiro; Nakanotani, Hajime; Adachi, Chihaya

    2015-03-25

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

  8. High-performance time-resolved fluorescence by direct waveform recording

    NASA Astrophysics Data System (ADS)

    Muretta, Joseph M.; Kyrychenko, Alexander; Ladokhin, Alexey S.; Kast, David J.; Gillispie, Gregory D.; Thomas, David D.

    2010-10-01

    We describe a high-performance time-resolved fluorescence (HPTRF) spectrometer that dramatically increases the rate at which precise and accurate subnanosecond-resolved fluorescence emission waveforms can be acquired in response to pulsed excitation. The key features of this instrument are an intense (1 μJ/pulse), high-repetition rate (10 kHz), and short (1 ns full width at half maximum) laser excitation source and a transient digitizer (0.125 ns per time point) that records a complete and accurate fluorescence decay curve for every laser pulse. For a typical fluorescent sample containing a few nanomoles of dye, a waveform with a signal/noise of about 100 can be acquired in response to a single laser pulse every 0.1 ms, at least 105 times faster than the conventional method of time-correlated single photon counting, with equal accuracy and precision in lifetime determination for lifetimes as short as 100 ps. Using standard single-lifetime samples, the detected signals are extremely reproducible, with waveform precision and linearity to within 1% error for single-pulse experiments. Waveforms acquired in 0.1 s (1000 pulses) with the HPTRF instrument were of sufficient precision to analyze two samples having different lifetimes, resolving minor components with high accuracy with respect to both lifetime and mole fraction. The instrument makes possible a new class of high-throughput time-resolved fluorescence experiments that should be especially powerful for biological applications, including transient kinetics, multidimensional fluorescence, and microplate formats.

  9. High-temperature reactive flow of combustion gases in an expansion turbine

    SciTech Connect

    Godin, T.; Harvey, S.; Stouffs, P.

    1997-07-01

    The analysis of the chemical behavior of the working fluid in gas turbines is usually restricted to the combustion chamber sections. However, the current trend toward higher Turbine Inlet Temperatures (TIT), in order to achieve improved thermal efficiency, will invalidate the assumption of frozen composition of the gases in the first stages of the expansion process. It will become necessary to consider the recombination reactions of the dissociated species, resulting in heat release during expansion. In order to quantify the influence of this reactivity on the performance of high TIT gas turbines, a one-dimensional model of the reactive flow has been developed. Preliminary results were reported in a previous paper. The authors concluded that, in the case of expansion of combustion gases in a subsonic static uncurved distributor nozzle, the residual reactivity must be taken into account above a temperature threshold of around 2,000 K. The present study extend these results by investigating the reactive flow in a complete multistage turbine set, including a transonic first-stage nozzle. A key result of this study is that heat release during the expansion process itself will be considerable in future high-temperature gas turbines, and this will have significant implications for turbine design techniques. Furthermore, they show that, at the turbine exit, the fractions of NO and CO are very different from the values computed at the combustor outlet. In particular, NO production in the early part of the expansion process is very high. Finally, the effects of temperature fluctuations at the turbine inlet are considered. They show that residual chemical reactivity affects the expansion characteristics in gas turbines with TITs comparable to those attained by modern high-performance machines.

  10. A parametric model for reactive high-power impulse magnetron sputtering of films

    NASA Astrophysics Data System (ADS)

    Kozák, Tomáš; Vlček, Jaroslav

    2016-02-01

    We present a time-dependent parametric model for reactive HiPIMS deposition of films. Specific features of HiPIMS discharges and a possible increase in the density of the reactive gas in front of the reactive gas inlets placed between the target and the substrate are considered in the model. The model makes it possible to calculate the compound fractions in two target layers and in one substrate layer, and the deposition rate of films at fixed partial pressures of the reactive and inert gas. A simplified relation for the deposition rate of films prepared using a reactive HiPIMS is presented. We used the model to simulate controlled reactive HiPIMS depositions of stoichiometric \\text{Zr}{{\\text{O}}2} films, which were recently carried out in our laboratories with two different configurations of the {{\\text{O}}2} inlets in front of the sputtered target. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 5 Wcm-2and 50 Wcm-2 with a pulse-averaged target power density up to 2 kWcm-2. The pulse durations were 50 μs and 200 μs. Our model calculations show that the to-substrate {{\\text{O}}2} inlet provides systematically lower compound fractions in the target surface layer and higher compound fractions in the substrate surface layer, compared with the to-target {{\\text{O}}2} inlet. The low compound fractions in the target surface layer (being approximately 10% at the deposition-averaged target power density of 50 Wcm-2 and the pulse duration of 200 μs) result in high deposition rates of the films produced, which are in agreement with experimental values.

  11. 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

  12. A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp3)-H amination

    NASA Astrophysics Data System (ADS)

    Paradine, Shauna M.; Griffin, Jennifer R.; Zhao, Jinpeng; Petronico, Aaron L.; Miller, Shannon M.; Christina White, M.

    2015-12-01

    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 (that is, tolerance of more oxidizable functionality) remains an unsolved problem. Here, 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 bond 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 such as rhodium, and stepwise radical C-H abstraction/rebound, as observed with chemoselective base metals such as iron. Rather than achieving a blending of effects, [Mn(tBuPc)] aminates even 1° aliphatic and propargylic C-H bonds, demonstrating reactivity and selectivity unusual for previously known catalysts.

  13. Amino-terminated biphenylthiol self-assembled monolayers as highly reactive molecular templates

    SciTech Connect

    Meyerbroeker, N.; Waske, P.; Zharnikov, M.

    2015-03-14

    Self-assembled monolayers (SAMs) with amino tail groups are of interest due to their ability of coupling further compounds. Such groups can be, in particular, created by electron irradiation of nitro- or nitrile-substituted aromatic SAMs, which provide a basis for chemical nanolithography and the fabrication of functionalized nanomembranes. An estimate of reactivity of the created amino groups requires a reference system of homogeneous, amino-terminated aromatic SAMs, which can also be used as a highly reactive molecular template. Here, we describe the synthesis of 4′-aminobiphenyl-4-thiol (ABPT) and SAMs prepared from this precursor on Au(111). The monolayers were characterized by X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy, which revealed that they are well defined, chemically uniform, densely packed, and highly ordered. To examine the influence of electron irradiation on the reactivity of the terminal amino groups, ABPT SAMs were exposed to low energy (50 eV) electrons up to a dose of 40 mC/cm{sup 2} and, subsequently, immersed in either trifluoroacetic, pentafluoropropionic, or heptafluorobutyric anhydride. Analysing the amount of the attached anhydride species made it possible to determine the percentage of reactive amino groups as well as the effect of steric hindrance upon the coupling reaction. The above results are compared with those obtained for the well-established nitro-substituted biphenylthiol monolayers.

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

    DOE PAGESBeta

    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 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

  15. 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.

  16. Magnetic Separation-Assistant Fluorescence Resonance Energy Transfer Inhibition for Highly Sensitive Probing of Nucleolin.

    PubMed

    Li, Yan-Ran; Liu, Qian; Hong, Zhangyong; Wang, He-Fang

    2015-12-15

    For the widely used "off-on" fluorescence (or phosphorescence) resonance energy transfer (FRET or PRET) system, the separation of donors and acceptors species was vital for enhancing the sensitivity. To date, separation of free donors from FRET/PRET inhibition systems was somewhat not convenient, whereas separation of the target-induced far-between acceptors has hardly been reported yet. We presented here a novel magnetic separation-assistant fluorescence resonance energy transfer (MS-FRET) inhibition strategy for highly sensitive detection of nucleolin using Cy5.5-AS1411 as the donor and Fe3O4-polypyrrole core-shell (Fe3O4@PPY) nanoparticles as the NIR quenching acceptor. Due to hydrophobic interaction and π-π stacking of AS1411 and PPY, Cy5.5-AS1411 was bound onto the surface of Fe3O4@PPY, resulting in 90% of fluorescence quenching of Cy5.5-AS1411. Owing to the much stronger specific interaction of AS1411 and nucleolin, the presence of nucleolin could take Cy5.5-AS1411 apart from Fe3O4@PPY and restore the fluorescence of Cy5.5-AS1411. The superparamagnetism of Fe3O4@PPY enabled all separations and fluorescence measurements complete in the same quartz cell, and thus allowed the convenient but accurate comparison of the sensitivity and fluorescence recovery in the cases of separation or nonseparation. Compared to nonseparation FRET inhibition, the separation of free Cy5.5-AS1411 from Cy5.5-AS1411-Fe3O4@PPY solution (the first magnetic separation, MS-1) had as high as 25-fold enhancement of the sensitivity, whereas further separation of the nucleolin-inducing far-between Fe3O4@PPY from the FRET inhibition solution (the second magnetic separation, MS-2) could further enhance the sensitivity to 35-fold. Finally, the MS-FRET inhibition assay displayed the linear range of 0.625-27.5 μg L(-1) (8.1-359 pM) and detection limit of 0.04 μg L(-1) (0.05 pM) of nucleolin. The fluorescence intensity recovery (the percentage ratio of the final restoring fluorescence intensity

  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. 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.

  19. 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. PMID:21796321

  20. Solvatochromic pyrene analogues of Prodan exhibiting extremely high fluorescence quantum yields in apolar and polar solvents.

    PubMed

    Niko, Yosuke; Kawauchi, Susumu; Konishi, Gen-ichi

    2013-07-22

    True colors: Novel pyrene analogues of Prodan exhibit outstanding photophysical properties with remarkably high fluorescence quantum yield (QY) in solvents ranging from apolar hexane to polar methanol (see figure). This is accompanied by strong solvatochromism and large Stokes shifts. These properties have not been previously achieved in enormous solvatochromic dyes, but are quite useful for emitting materials and imaging tools. PMID:23744761

  1. Thermally Activated Delayed Fluorescence in Polymers: A New Route toward Highly Efficient Solution Processable OLEDs.

    PubMed

    Nikolaenko, Andrey E; Cass, Michael; Bourcet, Florence; Mohamad, David; Roberts, Matthew

    2015-11-25

    Efficient intermonomer thermally activated delayed fluorescence is demonstrated for the first time, opening a new route to achieving high-efficiency solution processable polymer light-emitting device materials. External quantum efficiency (EQE) of up to 10% is achieved in a simple fully solution-processed device structure, and routes for further EQE improvement identified. PMID:26457683

  2. RADIOCHEMICAL ANALYSIS BY HIGH SENSITIVITY DUAL-OPTIC MICRO X-RAY FLUORESCENCE

    EPA Science Inventory

    A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries and...

  3. Determination of MDMA, MDEA and MDA in urine by high performance liquid chromatography with fluorescence detection.

    PubMed

    da Costa, José Luiz; da Matta Chasin, Alice Aparecida

    2004-11-01

    This paper describes the development and validation of analytical methodology for the determination of the use of MDMA, MDEA and MDA in urine. After a simple liquid extraction, the analyses were carried out on a high performance liquid chromatography (HPLC) in an octadecyl column, with fluorescence detection. The mobile phase using a sodium dodecyl sulfate ion-pairing reagent allows good separation and efficiency. The method showed good linearity and precision. Recovery was between 85 and 102% and detection limits were 10, 15 and 20 ng/ml for MDA, MDMA and MDEA, respectively. No interfering substances were detected with fluorescence detection. PMID:15458720

  4. 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

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

    SciTech Connect

    Forrest, Stephen; Zhang, Yifan

    2015-02-10

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

  6. A Low-Cost, High-Performance System for Fluorescence Lateral Flow Assays

    PubMed Central

    Lee, Linda G.; Nordman, Eric S.; Johnson, Martin D.; Oldham, Mark F.

    2013-01-01

    We demonstrate a fluorescence lateral flow system that has excellent sensitivity and wide dynamic range. The illumination system utilizes an LED, plastic lenses and plastic and colored glass filters for the excitation and emission light. Images are collected on an iPhone 4. Several fluorescent dyes with long Stokes shifts were evaluated for their signal and nonspecific binding in lateral flow. A wide range of values for the ratio of signal to nonspecific binding was found, from 50 for R-phycoerythrin (R-PE) to 0.15 for Brilliant Violet 605. The long Stokes shift of R-PE allowed the use of inexpensive plastic filters rather than costly interference filters to block the LED light. Fluorescence detection with R-PE and absorbance detection with colloidal gold were directly compared in lateral flow using biotinylated bovine serum albumen (BSA) as the analyte. Fluorescence provided linear data over a range of 0.4–4,000 ng/mL with a 1,000-fold signal change while colloidal gold provided non-linear data over a range of 16–4,000 ng/mL with a 10-fold signal change. A comparison using human chorionic gonadotropin (hCG) as the analyte showed a similar advantage in the fluorescent system. We believe our inexpensive yet high-performance platform will be useful for providing quantitative and sensitive detection in a point-of-care setting. PMID:25586412

  7. 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-.

  8. 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

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

    PubMed

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

    2014-08-01

    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

  10. 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.